JP2020202640A - Cut-off circuit - Google Patents

Abstract

To provide a mechanism that enables stable operation of a load connected to a power storage circuit.SOLUTION: A cut-off circuit 70 includes: an input terminal 72; an output terminal 78; and a power supply detection terminal 74. The output terminal 78 of the cut-off circuit 70 is connected to a load 62 which operates with electric power supplied from a power storage circuit 30. The cut-off circuit 70 blocks the output terminal 78 from the input terminal 72 if a voltage applied to the power supply detection terminal 74 is equal to a prescribed voltage or less, whereas the output terminal 78 is conducted to the input terminal 72 when the voltage applied to the power supply detection terminal 74 is larger than the prescribed voltage.SELECTED DRAWING: Figure 5

Description

The present invention relates to a breaking circuit.

Non-Patent Document 1 discloses a power storage circuit that supplies electric power to a load.

Referring to FIG. 13, in the power storage circuit 90 disclosed in Non-Patent Document 1, the power supply 92 stores a minute amount of electric power generated by energy harvesting and supplies it to the load 98. The power storage circuit 90 includes a power supply line 93, a capacitor (not shown), a voltage detection circuit 94, a comparison circuit 95, a pull-up resistor 96 including a resistor R1, and a switch circuit 97. The capacitor is connected to the power supply line 93 (not shown). The voltage detection circuit 94, the comparison circuit 95, the pull-up resistor 96, and the switch circuit 97 have the circuit structure shown in FIG. For example, the voltage detection circuit 94 includes a Zener diode Z1 having a Zener voltage VZ, and the comparison circuit 95 includes an open-drain comparator 952. Further, the switch circuit 97 includes a switching element S1 and a switching element S2.

The capacitor (not shown) stores the power generated by the power supply 92, which produces a voltage Vin in the power supply line 93. The voltage detection circuit 94 generates a voltage Vr based on the voltage Vin and the Zener voltage VZ, and also generates a voltage Vd obtained by dividing the voltage Vin. A voltage Vp corresponding to the voltage Vd is applied to the positive input end of the comparator 952, and a voltage Vr is applied to the negative input end of the comparator 952. The comparison circuit 95 applies a voltage generated based on the comparison result between the voltage Vp and the voltage Vr to the gate of the switching element S1. The switching element S2 is between a cutoff state (a state in which the load 98 is cut off from the power supply 92) and a conduction state (a state in which the load 98 is connected to the power supply 92) according to the voltage applied to the gate of the switching element S1. To transition. That is, the power storage circuit 90 can transition between the cutoff state and the conduction state.

According to Non-Patent Document 1, when the power supply 92 generates electric power when the capacitor (not shown) is empty, the electric power is gradually accumulated in the capacitor, and the voltage Vin and the voltage Vp gradually increase. The power storage circuit 90 maintains the cutoff state until the voltage Vp reaches the voltage Vr, and the power generated by the power supply 92 is stored in the capacitor without being consumed by the load 98. After the capacitor is sufficiently charged, the voltage Vp becomes equal to or higher than the voltage Vr, and the power storage circuit 90 becomes conductive. At this time, a sufficiently large amount of electric power is supplied to the load 98.

Hitoshi Ono, 3 outsiders, "Development of energy saving and energy harvesting technology applying switching circuit", 2015 Miyagi Prefectural Industrial Technology Center Research Report, Miyagi Prefecture (Industrial Technology Center), September 2016, No. 13 (2015), p. 1-7

The power storage circuit 90 disclosed in Non-Patent Document 1 theoretically operates as described above. However, when the circuit is actually configured and tested, the load 98 may not operate stably.

Therefore, an object of the present invention is to provide a mechanism that enables stable operation of a load connected to a power storage circuit.

As a result of research by the inventor of the present application, it has been found that the switch circuit may become conductive before the capacitor is sufficiently charged due to the circuit structure of the power storage circuit. Therefore, the inventor of the present application has invented a new power storage circuit capable of appropriately transitioning the switch circuit between the cutoff state and the conduction state. The new power storage circuit has been filed in Japan as Japanese Patent Application No. 2017-248693.

However, as a result of further research by the inventor of the present application, it has been found that the load may not operate stably even if the above-mentioned new power storage circuit is used. In particular, it was found that when a load (for example, a sensor that measures the voltage of an external circuit) to which a voltage is applied from an external circuit other than the power storage circuit is connected to the power storage circuit, the load may not operate stably. It was. It is considered that this is because the load performs an unexpected operation when a voltage is applied to the load from the external circuit when the power storage circuit is in the cutoff state (that is, when the load is not operating). Therefore, the present invention provides a breaking circuit capable of breaking a non-operating load from an external circuit. Specifically, the present invention provides the following break circuit.

The present invention provides the first break circuit.
A breaking circuit having an input end, an output end, and a power supply detection end.
The output end of the break circuit is connected to a load operated by electric power supplied from the power storage circuit.
When the voltage applied to the power supply detection end is equal to or less than a predetermined voltage, the output end is cut off from the input end, while when the voltage applied to the power supply detection end is larger than the predetermined voltage, the output end is cut off. Is provided with a cutoff circuit for conducting with the input terminal.

Further, the present invention is a first breaking circuit as a second breaking circuit.
The power storage circuit is a circuit that stores electric power supplied from a power source and supplies it to the load.
The power storage circuit includes a power supply line, a power storage unit, and a control unit.
The power supply line connects the power supply and the load to each other.
The power storage unit is connected to the power supply line, accumulates the power supplied from the power supply, and applies a supply voltage larger than zero to the power supply line.
The control unit cuts off the load from the power storage unit until the supply voltage starts from zero and reaches the start voltage.
After the supply voltage reaches the start voltage, the control unit conducts the load with the power storage unit until the supply voltage drops to the stop voltage, and when the supply voltage drops to the stop voltage, the control unit causes the load. The load is cut off from the power storage unit until the supply voltage reaches the start voltage again.
The power detection end of the break circuit provides a break circuit that is directly or indirectly connected to a detection point on the power line.

Further, the present invention is a second breaking circuit as a third breaking circuit.
Provided is a cutoff circuit in which the voltage at the detection point is the ground voltage when the load is cut off from the power storage unit, and is higher than the ground voltage when the load is conducting with the power storage unit. To do.

Further, the present invention is a second or third breaking circuit as the fourth breaking circuit.
The power storage circuit includes a switch unit.
The switch unit is connected between the power storage unit and the load in the power supply line.
The switch portion has a switch end and has a switch end.
When the voltage applied to the switch end is lower than the predetermined threshold value, the switch unit takes a cutoff state in which the load is cut off from the power storage unit, and the voltage applied to the switch end is higher than the predetermined threshold value. In the case, a conductive state is taken in which the load is made conductive with the power storage unit.
The control unit is connected between the power storage unit and the switch unit in the power supply line.
The control unit applies a voltage lower than the predetermined threshold value to the switch end until the supply voltage starts from zero and reaches the start voltage.
After the supply voltage reaches the start voltage, the control unit applies a voltage higher than the predetermined threshold voltage to the switch end until the supply voltage drops to the stop voltage, and the supply voltage becomes the supply voltage. When the voltage drops to the stop voltage, a cutoff circuit is provided at the switch end for applying a voltage lower than the predetermined threshold until the supply voltage reaches the start voltage again.

Further, the present invention is a second or third breaking circuit as the fifth breaking circuit.
The power storage circuit includes a capacitor that functions as the power storage unit and a switch circuit.
The control unit of the power storage circuit includes a voltage detection circuit, a comparison circuit, and an additional circuit.
The voltage detection circuit has a detection input end connected to the power supply line, a reference output end that outputs a reference voltage, and a detection output end that outputs a detection voltage.
The reference voltage is the supply voltage when the supply voltage is lower than the reference voltage, and is the reference voltage when the supply voltage is equal to or higher than the reference voltage.
The detection voltage changes according to the supply voltage and is lower than the supply voltage.
The comparison circuit has a positive input end connected to the power supply line and connected to the reference output end, a negative input end connected to the detection output end, and an output that outputs an additional control voltage. Has an edge and
The additional control voltage is a high voltage corresponding to the supply voltage when the voltage applied to the positive input end is higher than the voltage applied to the negative input end, and is applied to the positive input end. When the voltage is lower than the voltage applied to the negative input end, it is a low voltage corresponding to the ground voltage.
The additional circuit has a power supply end connected to the power supply line and a grounded ground end, and has a non-ground state that cuts off between the power supply end and the ground end, and the power supply end. Can be transitioned between the ground end and the ground state that conducts
The switch circuit is connected between the capacitor and the load in the power supply line, and transitions between a cutoff state in which the load is cut off from the capacitor and a conduction state in which the load is conducted with the capacitor. It is possible and
The additional circuit has an additional input end connected to the output end of the comparison circuit and a switch control end that outputs a control voltage.
The control voltage is a high voltage corresponding to the supply voltage when the additional circuit is in the non-ground state, and is a low voltage corresponding to the ground voltage when the additional circuit is in the ground state. Yes,
The additional circuit is in the non-ground state until the supply voltage rises from zero and the additional applied voltage applied to the additional input end in response to the additional control voltage reaches an additional threshold. After the additional applied voltage reaches the additional threshold value, if the additional applied voltage is higher than the additional threshold value, the ground state is taken and the additional applied voltage is the additional threshold value. If it is lower than, take the non-ground state and
The switch circuit has a switch end connected to the switch control end.
The switch circuit takes the cutoff state until the supply voltage rises from zero and the applied voltage applied to the switch end reaches a predetermined threshold value according to the control voltage, and the applied voltage is the predetermined voltage. After reaching the threshold value, when the applied voltage is higher than the predetermined threshold value, the conduction state is taken, and when the applied voltage is lower than the predetermined threshold value, the cutoff state is taken.
The applied voltage provides a power storage circuit that is lower than the predetermined threshold until the supply voltage rises from zero and the additional applied voltage reaches the additional threshold.

Further, the present invention is a fifth breaking circuit as a sixth breaking circuit.
The power supply end of the additional circuit is connected to the power supply line and is also connected to the detection output end of the voltage detection circuit.
The control voltage provides a power storage circuit that is a high voltage corresponding to the detection voltage when the additional circuit is in the non-ground state.

Further, the present invention is a sixth breaking circuit as a seventh breaking circuit.
The additional circuit includes an additional switching element composed of an N-type MOSFET (metal-oxide-semiconductor field-effect transistor).
In the additional switching element, the gate functions as the additional input end, the source functions as the ground end, the drain functions as the power supply end, and the detection output end of the voltage detection circuit. Is connected to the switch end of the switch circuit.
The additional threshold is a threshold of the potential difference between the gate and the source for conducting the conduction between the source and the drain in the additional switching element.
The switch circuit includes a main switching element made of a P-type MOSFET and a sub-switching element made of an N-type MOSFET.
In the main switching element, the source is connected to the power supply side of the power supply line, and the drain is connected to the load side of the power supply line.
In the sub-switching element, the gate functions as the switch end, the source is grounded, and the drain is connected to the source of the main switching element via two resistors.
The gate of the main switching element is connected between the two resistors.
The predetermined threshold value provides a storage circuit which is a threshold value of a potential difference between the gate and the source for conducting between the source and the drain in the sub-switching element.

Further, the present invention is any of the fifth to seventh breaking circuits as the eighth breaking circuit.
The predetermined threshold value provides a power storage circuit that is equal to or higher than the additional threshold value.

According to the cutoff circuit of the present invention, when the voltage applied to the power supply detection end is equal to or less than a predetermined voltage, the cutoff is performed between the input end and the output end. Further, the output end of the cutoff circuit of the present invention is connected to a load operated by the electric power supplied from the power storage circuit. For example, the load is a sensor that measures the voltage applied to the measurement end of the load by an external circuit. In this case, the input end of the cutoff circuit may be connected to the external circuit, and the output end of the cutoff circuit may be connected to the measurement end of the sensor. According to this configuration, by applying the voltage received by the sensor from the power storage circuit to the power supply detection end of the cutoff circuit, when the power storage circuit is in the cutoff state (that is, when the sensor is not operating), the sensor is external. It is cut off from the circuit. That is, according to the present invention, it is possible to provide a cutoff circuit capable of cutting off a load that is not operating from an external circuit, thereby providing a mechanism that enables stable operation of the load connected to the power storage circuit.

It is a block diagram which shows the electricity storage type system by embodiment of this invention. It is a figure which shows typically the operation of the power storage circuit of the power storage type system of FIG. It is a figure which shows typically the circuit structure of the load (sensor) when the switch part of the power storage circuit of FIG. 1 is in a conductive state. It is a figure which shows typically the circuit structure of the load (sensor) when the switch part of the power storage circuit of FIG. 1 is in a cutoff state. It is a block diagram which shows the electricity storage type system of FIG. 1 in the state which provided the cutoff circuit. It is a circuit diagram which shows the cutoff circuit of FIG. It is a block diagram which shows the modification of the storage type system of FIG. It is a circuit diagram which shows the modification of the cutoff circuit of FIG. It is a block diagram which shows an example of the power storage circuit of FIG. It is a circuit diagram which shows an example of the power storage circuit of FIG. 9 is a diagram schematically showing the operation of the power storage circuit of FIGS. 9 and 10. It is a figure which shows the operation of the power storage circuit of the Example of this invention. It is a circuit diagram which shows the power storage circuit of Non-Patent Document 1.

Referring to FIG. 1, the power storage type system 10 according to the embodiment of the present invention includes a power supply 20, a power storage circuit 30, and a load 60.

The power source 20 of the present embodiment generates a minute electric power of about 10 μW to 1 mW by harvesting a minute energy from the surrounding environment (that is, by energy harvesting), and also generates a minute voltage. The power source 20 is, for example, a power generator such as a photovoltaic cell, a thermoelectric element, or a vibration power generator after rectification. The power source 20 may be one of the above-mentioned generators, or may include two or more of the above-mentioned generators.

The load 60 of the present embodiment is, for example, a step-up DC-DC converter, a step-down DC-DC converter, a buck-boost DC-DC converter (hereinafter collectively referred to as “DC-DC converter”), a sensor, and a microcomputer. , Electronic devices including semiconductor elements such as wireless devices, and electronic devices such as small motors that require a certain voltage or higher at the start of operation. The load 60 may be one of the above-mentioned electronic devices, or may include two or more of the above-mentioned electronic devices.

The power storage circuit 30 of the present embodiment is a circuit incorporated in a power storage device (not shown). The power storage device of the present embodiment is an electronic device separate from the power supply 20 and the load 60. However, the present invention is not limited to this. For example, the power storage device may be one electronic device including a power supply 20, a power storage circuit 30, and a load 60. Further, the power storage circuit 30 may be a circuit incorporated in the load 60.

The load 60 of the present embodiment repeatedly transitions between the operating state and the standby state at the time of use. The power consumption of the load 60 in the standby state is significantly lower than the power consumption in the operating state. On the other hand, the power consumption (operating power) in the operating state of the load 60 is about several mW to several W, which is larger than the power that can be directly supplied by the power source 20. Therefore, when the load 60 is directly connected to the power supply 20, the power supply 20 causes a voltage drop, and the voltage of the power supply 20 does not reach the voltage for properly operating the load 60 (operation start voltage VS).

On the other hand, as described below, the power storage circuit 30 of the present embodiment stores a minute amount of electric power (electrostatic energy) generated by the power source 20, and when the electric power is sufficiently accumulated, a required high voltage is obtained. Powers the load 60. However, the present invention is not limited to this. For example, the power storage circuit 30 may be connected to a power source 20 that produces high power and voltage that can be directly supplied to the load 60.

As described above, the power storage circuit 30 of the present embodiment is a circuit that stores the power supplied from the power supply 20 and supplies it to the load 60, and is a power supply line 12, a power storage unit (capacitor) 32, and a control unit. It includes 40 and a switch unit (switch circuit) 50. Hereinafter, the structure and function of each part of the power storage circuit 30 will be described.

The power supply line 12 of the power storage circuit 30 connects the power supply 20 and the load 60 to each other. Specifically, the power supply line 12 includes an input side power supply line (power supply line) 122 and an output side power supply line (power supply line) 126. The power supply line 122 connects the power supply 20 and one end of the switch unit 50 to each other, and the power supply line 126 connects the other end of the switch unit 50 and the load 60 to each other. In other words, the switch unit 50 is provided between the power supply line 122 and the power supply line 126. That is, the power supply 20 and the load 60 are connected to each other by the power supply line 12 via the switch unit 50.

As described above, the switch unit 50 of the power storage circuit 30 is connected between the power storage unit 32 and the load 60 in the power supply line 12. Further, the switch unit 50 has a switch end 56. When the applied voltage Vx applied to the switch end 56 is lower than a predetermined voltage value (predetermined threshold value TP), the switch unit 50 takes a cutoff state in which the load 60 is cut off from the power supply 20 and is applied to the switch end 56. When the applied voltage Vx is higher than the predetermined threshold value TP, a conductive state is taken in which the load 60 is conducted to the power supply 20. That is, the switch unit 50 can transition between the cutoff state and the conductive state according to the applied voltage Vx. The switch unit 50 is in a cutoff state when the power supply 20 starts supplying electric power to the power storage circuit 30.

As described above, the switch unit 50 that transitions between the cutoff state and the conduction state can be configured by using electronic components such as a P-type MOSFET (metal-oxide-semiconductor field-effect transistor) and an N-type MOSFET. The predetermined threshold value TP is, for example, a threshold value of the potential difference between the gate and the source for conducting or blocking the conduction or cutoff between the source and the drain in the MOSFET (hereinafter, simply referred to as “gate threshold value”).

The power storage unit 32 of the power storage circuit 30 is connected to the power supply line 122 (power supply line 12). Therefore, when the switch unit 50 is in the cutoff state, the power storage unit 32 is cut off from the load 60. On the other hand, when the switch unit 50 is in the conductive state, the power storage unit 32 is conductive with the load 60.

The power storage unit 32 stores a minute amount of electric power supplied from the power source 20 and applies a supply voltage Vin larger than zero to the power supply line 122 (power supply line 12). When the switch unit 50 is in the cutoff state, the supply voltage Vin rises above the operation start voltage VS of the load 60 as the electric power is stored in the power storage unit 32. The power storage circuit 30 can store sufficient electrostatic energy in the power storage unit 32 for operating the load 60 by shutting off the switch unit 50 for a predetermined time. In addition, the power storage circuit 30 puts the switch unit 50 into a conductive state when sufficient electrostatic energy is stored in the power storage unit 32. When the switch unit 50 becomes conductive, power is supplied to the load 60 by an output voltage Vout higher than the operation start voltage VS of the load 60. The supply voltage Vin gradually drops as power is supplied to the load 60.

As described above, the power storage unit 32 that stores electric power can be composed of, for example, one capacitor. However, the present invention is not limited to this. For example, the power storage unit 32 may be composed of two or more capacitors, or may include electronic components other than the capacitors. When the power storage unit 32 includes two or more capacitors, the connection method between the capacitors is not particularly limited. Further, the power storage unit 32 can be composed of various capacitors such as an electrolytic capacitor, a ceramic capacitor, and an electric double layer capacitor.

The control unit 40 of the power storage circuit 30 is connected to the power supply line 122 (power supply line 12). Specifically, the control unit 40 is connected between the power storage unit 32 and the switch unit 50 in the power supply line 122, whereby the supply voltage Vin can be detected. In addition, the control unit 40 is connected to the switch end 56 of the switch unit 50, and applies the applied voltage Vx to the switch end 56.

Referring to FIG. 2 together with FIG. 1, the control unit 40 controls the switch unit 50 by the applied voltage Vx to make a transition between the cutoff state and the conduction state.

In the present embodiment, the control unit 40 applies a voltage lower than the predetermined threshold value TP to the switch end 56 until the supply voltage Vin starts from zero and reaches a start voltage VH sufficiently larger than the operation start voltage VS. It is applied as a voltage Vx. That is, the control unit 40 keeps the switch unit 50 in the cutoff state until the supply voltage Vin starts from zero and reaches the start voltage VH, thereby shutting off the load 60 from the power storage unit 32.

After the supply voltage Vin reaches the start voltage VH, the control unit 40 sets a predetermined threshold value at the switch end 56 until the supply voltage Vin drops to a stop voltage VL that is smaller than the start voltage VH and larger than the operation start voltage VS. A voltage higher than TP is applied as the applied voltage Vx. That is, when the supply voltage Vin reaches the start voltage VH, the control unit 40 shifts the switch unit 50 from the cutoff state to the conduction state. After the supply voltage Vin reaches the start voltage VH, the control unit 40 keeps the switch unit 50 in a conductive state until the supply voltage Vin drops to the stop voltage VL, whereby the load 60 is made conductive with the power storage unit 32. ..

When the supply voltage Vin drops to the stop voltage VL, the control unit 40 applies a voltage lower than the predetermined threshold voltage TP to the switch end 56 as the applied voltage Vx until the supply voltage Vin reaches the start voltage VH again. That is, when the supply voltage Vin drops to the stop voltage VL, the control unit 40 shifts the switch unit 50 from the conduction state to the cutoff state. When the supply voltage Vin drops to the stop voltage VL, the control unit 40 keeps the switch unit 50 in the cutoff state until the supply voltage Vin reaches the start voltage VH again, thereby shutting off the load 60 from the power storage unit 32.

The control unit 40 that operates as described above can be configured by using electronic components such as an open drain comparator, a P-type MOSFET, and an N-type MOSFET.

The power storage circuit 30 configured as described above is in the initial state from the supply voltage Vin starting from zero until the starting voltage VH is first reached. When the power storage circuit 30 is in the initial state, the control unit 40 maintains the switch unit 50 in the cutoff state. The power storage circuit 30 enters a steady state when the switch unit 50 first transitions to the conductive state, and thereafter maintains the steady state as long as power is continuously supplied from the power source 20. When the power storage circuit 30 is in the steady state, the control unit 40 repeatedly transitions the switch unit 50 between the conduction state and the cutoff state.

As can be understood from the above description, when the switch unit 50 is in the conductive state, power is supplied to the load 60 by an output voltage Vout higher than the operation start voltage VS. As a result, the load 60 takes an operating state or a standby state and operates appropriately. On the other hand, when the switch unit 50 is in the cutoff state, power is not supplied to the load 60. As a result, the load 60 takes a stopped state and does not operate. The load 60 should theoretically operate stably as described above.

However, referring to FIG. 13, when the storage type system is actually configured and tested, the load 98 may not operate stably. As a result of research on this phenomenon, due to the circuit structure of the conventional power storage circuit 90, the switch circuit 97 (switch part) is in a conductive state before the power storage unit (capacitor not shown in FIG. 13) is sufficiently charged. It turns out that it may become. With reference to FIGS. 1, 9 and 10, the power storage circuit 30 of the present embodiment was invented based on the above considerations, and appropriately switches the switch unit 50 between the cutoff state and the conduction state. It can be transitioned. The invention relating to the circuit structure of the power storage circuit 30 has been filed in Japan as Japanese Patent Application No. 2017-248693.

However, when an experiment was carried out by actually configuring the power storage circuit 30, it was found that the load 60 may not operate stably even if the power storage circuit 30 is used. Referring to FIG. 3, in particular, a load 62 (for example, a sensor 62 for measuring the voltage of the external circuit) to which a voltage is applied from an external circuit (not shown) other than the power storage circuit 30 is connected to the power storage circuit 30. In that case, it was found that the load 62 may not operate stably. The reason for this is that when a voltage is applied to the load 62 from the external circuit when the switch unit 50 is in the cutoff state (that is, when the load 62 is not operating), the load 62 performs an unexpected operation. it is conceivable that.

Hereinafter, the cause of the load 62 not operating stably will be described with reference to FIGS. 3 and 4 when the load 62 and the load 64 are connected to the power storage circuit 30. The load 62 of the present embodiment is a sensor 62 that measures the voltage of an external circuit (not shown), and has a resistor R61 formed according to the design and a measurement end 622 connected to the external circuit. ing. The measurement end 622 is in a high impedance state or in a state close to a high impedance state when the load 62 is in the operating state or the standby state. In other words, the load 62 of the present embodiment is a sensor having a measurement end 622 that is in a high impedance state or a state close to a high impedance state in the operating state and the standby state. On the other hand, the load 64 of the present embodiment is a DC-DC converter 64, and has a resistor R64 formed according to the design. However, the load 64 may be an electronic device other than a DC-DC converter such as a microcomputer.

Referring to FIG. 3, the measurement voltage Vxin of the external circuit is applied to the measurement end 622 of the load 62. When the switch unit 50 of the power storage circuit 30 is in the conductive state, the load 62 and the load 64 are in the operating state or the standby state, respectively. At this time, since the measurement end 622 is in a high impedance state or a state close to a high impedance state, it is substantially cut off from the power supply line 126 (power supply line 12). Specifically, the current flowing from the external circuit to the measurement end 622 is used, for example, only for A / D conversion of the load 62. Therefore, the current flowing from the external circuit to the measurement end 622 does not interfere with the operation of the load 62 and the load 64, respectively.

On the other hand, referring to FIG. 4, when the switch unit 50 of the power storage circuit 30 is in the cutoff state, the load 62 and the load 64 are in the stopped state, respectively. At this time, the measurement end 622 of the load 62 may not be in the high impedance state. More specifically, due to the circuit structure of the load 62, an unexpected resistor R62 may be formed between the measurement end 622 and the power supply line 126 (power supply line 12). That is, the measurement end 622 may conduct with the power supply line 126 via the resistor R62. In this case, the current flowing from the external circuit (not shown) to the measurement end 622 flows through the circuit of the load 62, which may hinder the operation of the load 62. Further, the current flowing from the external circuit to the measurement end 622 may flow into the load 64 via the power supply line 126.

Generally, when the load 60 including the load 62 and the load 64 (see FIG. 1) is in the stopped state, if a current that does not pass through the power supply line 126 flows into the load 60, the load 60 malfunctions or fails. There is a risk. In addition, the current of the external circuit (external device: not shown) connected to the measurement end 622 of the load 62 is deprived. As a result, the current consumption of the external device may increase or the external device may break down.

On the other hand, referring to FIG. 5, the power storage type system 10 of the present embodiment includes a cutoff circuit 70 in addition to the power supply 20, the power storage circuit 30, and the load 60. The load 60 includes one or more loads (sensors) 62. That is, the power storage type system 10 shown in FIG. 5 is a sensor system including a sensor 62 as one of the loads 60. Each of the loads 62 is connected to an external circuit (not shown) via a break circuit 70. The ground voltage of the external circuit coincides with the ground voltage of the storage type system 10. As will be described below, in such a power storage type system 10 (sensor system), by providing the cutoff circuit 70, each of the loads 60 including the load 62 can be stably operated.

Referring to FIG. 6, the cutoff circuit 70 has an input end 72, an output end 78, and a power supply detection end 74. The input terminal 72 of the cutoff circuit 70 is connected to an external circuit (not shown). The measurement voltage Vxin of the external circuit is applied to the input terminal 72 connected in this way. The output terminal 78 of the cutoff circuit 70 is connected to a load 62 operated by the electric power supplied from the power storage circuit 30. Specifically, the output end 78 is connected to the measurement end 622 of the load 62. The output terminal 78 connected in this way applies a measurement voltage Vxout having substantially the same voltage as the measurement voltage Vxin to the measurement end 622.

Referring to FIG. 5, the power supply detection end 74 of the cutoff circuit 70 is connected to the detection point 162 of the power supply line 126 (power supply line 12). A detection voltage Vxd corresponding to the output voltage Vout is applied to the power supply detection terminal 74 connected in this way. According to this embodiment, when the switch unit 50 of the power storage circuit 30 is in a conductive state, an output voltage Vout higher than the operation start voltage VS of the load 62 is applied to the power supply detection terminal 74. On the other hand, as can be understood from FIGS. 3 and 4, when the switch unit 50 is in the cutoff state, the power supply line 126 is quickly grounded, whereby the output voltage Vout, which is the ground voltage, is applied to the power supply detection terminal 74. Will be done.

Referring to FIG. 6, the cutoff circuit 70 of the present embodiment includes a first element 702 made of a P-type MOSFET, a second element 704 made of an N-type MOSFET, and three resistors R71, R72, R73. There is. The first element 702, the second element 704, and the resistors R71, R72, and R73 are connected as shown in FIG.

According to this embodiment, the detection voltage Vxd is applied to the gate of the second element 704. When the detection voltage Vxd is lower than the gate threshold value of the second element 704, the source and the drain of the second element 704 are cut off, and the gate of the first element 702 has a voltage having the same potential as the source of the first element 702. Is applied. As a result, the source and drain of the first element 702 are cut off. That is, the connection between the input end 72 and the output end 78 of the cutoff circuit 70 is cut off.

On the other hand, when the detection voltage Vxd is higher than the gate threshold value of the second element 704, the source and drain of the second element 704 conduct with each other, and the gate of the first element 702 is grounded via the resistor R72. As a result, the voltage applied to the gate of the first element 702 becomes lower than the voltage applied to the source of the first element 702. Therefore, by appropriately setting the resistance values of the resistor R71 and the resistor R72 in consideration of the gate threshold value of the first element 702, the source and the drain of the first element 702 become conductive. That is, there is conduction between the input end 72 and the output end 78 of the cutoff circuit 70.

As can be understood from the above description, when the voltage applied to the power supply detection end 74 is equal to or lower than the predetermined voltage VP, the cutoff circuit 70 cuts off the output end 78 from the input end 72 while cutting off the power supply detection end 74 to the power supply detection end 74. When the applied voltage is larger than the predetermined voltage VP, the output end 78 is made conductive with the input end 72. In the present embodiment, the predetermined voltage VP is the gate threshold value of the second element 704. However, the present invention is not limited to this, and the predetermined voltage VP is determined according to the circuit structure of the breaking circuit 70.

Referring to FIG. 5, according to the cutoff circuit 70, when the detection voltage Vxd applied to the power supply detection end 74 is equal to or lower than the predetermined voltage VP, the cutoff is performed between the input end 72 and the output end 78. Further, as described above, the output terminal 78 of the cutoff circuit 70 is connected to the load 62. The load 62 is a sensor 62 that measures the voltage applied to the measurement end 622 of the load 62 by an external circuit (not shown).

According to the present embodiment, when the switch portion 50 of the power storage circuit 30 is in the cutoff state by applying the voltage received by the load 62 from the power storage circuit 30 to the power supply detection terminal 74 of the cutoff circuit 70 (that is, the load 62). Is in a stopped state and is not operating), the load 62 is cut off from an external circuit (not shown). That is, according to the present invention, it is possible to provide a cutoff circuit 70 capable of cutting off a non-operating load 62 from an external circuit, whereby a mechanism that enables stable operation of the load 62 connected to the power storage circuit 30. Can be provided.

Specifically, when the load 62 is in the stopped state, the current flowing from the external circuit (not shown) to the cutoff circuit 70 does not flow to the load 62, so that the load 60 such as the load 62 and the load 64 (see FIG. 4) Does not interfere with movement. In addition, malfunctions and failures of the load 60 due to the current from the external circuit are prevented. In addition, the increase in current consumption of the external circuit (external device) and the failure of the external device are prevented.

Since the power supply 20 of the present embodiment generates electric power depending on the surrounding environment, the electric power storage unit 32 may not be supplied with electric power for a long time. In this case, the supply voltage Vin generated by the power storage unit 32 tends to be relatively 0V. In such a power storage type system 10, the cutoff circuit 70 is particularly necessary. However, the present invention is not limited to this, and the cutoff circuit 70 can be applied to various power storage type systems. For example, the cutoff circuit 70 may be applied to a conventional power storage type system.

According to this embodiment, the power supply detection end 74 of the cutoff circuit 70 is directly connected to the detection point 162 on the power supply line 126. The voltage at the detection point 162 is a ground voltage when the load 60 is cut off from the power storage unit 32, and is an output voltage Vout higher than the ground voltage when the load 60 is conducting with the power storage unit 32. According to this structure, the circuit structure of the cutoff circuit 70 can be simplified. However, the present invention is not limited to this, and the connection method of the power supply detection terminal 74 can be variously modified.

For example, the detection point 162 to which the power supply detection end 74 is connected may be located on the power supply line 122. However, according to this connection method, the cutoff circuit 70 needs to have a circuit structure such that the input end 72 and the output end 78 are electrically connected only when the voltage at the detection point 162 is falling. .. As a result, the circuit structure of the break circuit 70 becomes complicated. Therefore, unless there is a particular need, the connection method of the present embodiment is preferable to this connection method.

Referring to FIG. 7, the illustrated load 60 includes a load (microcomputer) 66 in addition to the load (sensor) 62. The load 66 has a control end 668. When the voltage at the detection point 162A on the power supply line 126 is higher than the ground voltage, the control terminal 668 of the load 66 outputs a voltage (High) higher than the predetermined voltage VP of the cutoff circuit 70, and the voltage at the detection point 162A becomes When it is the ground voltage, it outputs a voltage (Low) lower than the predetermined voltage VP of the cutoff circuit 70. That is, the load 66 outputs either High or Low to the control terminal 668 according to the voltage at the detection point 162A. The power supply detection end 74 of the cutoff circuit 70 is connected to the control end 668 of the load 66. The input end 72 of the cutoff circuit 70 is connected to an external circuit (not shown), and the output end 78 of the cutoff circuit 70 is connected to the measurement end 622 of the load 62.

The power supply detection end 74 of the cutoff circuit 70 of FIG. 7 is connected to the control end 668 of the load 66. Therefore, the power supply detection end 74 is indirectly connected to the detection point 162A on the power supply line 126 via the load 66. Even with this connection structure, when the load 62 is cut off from the power storage unit 32, the measurement end 622 of the load 62 can be reliably cut off from an external circuit (not shown). Further, according to this connection structure, the load 66 can be set so that High is output to the control end 668 only when the measurement by the load 62 is actually performed. Referring to FIG. 6, according to this setting, the power consumption due to the resistor R73 of the break circuit 70 can be reduced.

The circuit structure of the break circuit 70 is variously deformable. For example, referring to FIG. 8, the breaking circuit 70A according to the modified example includes two resistors R74 and R75 in addition to the parts of the breaking circuit 70 (see FIG. 6). Similar to the cutoff circuit 70, the cutoff circuit 70A cuts off the output end 78 from the input end 72 when the voltage applied to the power supply detection end 74 is equal to or lower than the predetermined voltage VP, while the cutoff circuit 70A is applied to the power supply detection end 74. When the voltage is larger than the predetermined voltage VP, the output end 78 is made conductive with the input end 72.

However, unlike the cutoff circuit 70, the cutoff circuit 70A divides the measurement voltage Vxin applied to the input end 72 by the external circuit (not shown) by the resistors R74 and R75 and applies it to the measurement end 622 of the load 62. According to this voltage dividing mechanism, when the measured voltage Vxin is higher than the voltage that the load 62 can measure, the measured voltage Vxout can be lowered to the voltage that the load 62 can measure.

According to the cutoff circuit 70A, when the output end 78 is conducting with the input end 72, the current flowing into the input end 72 continues to flow through the resistor R74 and the resistor R75 and is consumed. From the viewpoint of suppressing such current consumption, the power supply detection end 74 of the cutoff circuit 70A is connected to the control end 668 of the load 66 (see FIG. 7), thereby causing the current flowing through the resistors R74 and R75 to flow. It is preferably controlled by the load 66.

Referring to FIGS. 5 to 8, each of the illustrated breaking circuit 70 and breaking circuit 70A is connected to a load 62 which is a sensor 62. However, the present invention is not limited to this. For example, the load 62 may be an electronic device that operates in response to a control signal received from an external circuit (not shown). In this case as well, the cutoff circuit 70 or the cutoff circuit 70A may be connected between the external circuit and the load 62.

Hereinafter, the structure and function of the power storage circuit 30 according to the present embodiment will be described in more detail.

Referring to FIG. 9 together with FIG. 1, the power storage circuit 30 includes a capacitor 32 that functions as a power storage unit 32 and a switch circuit 50 that functions as a switch unit 50. The control unit 40 of the power storage circuit 30 includes a voltage detection circuit 44, a comparison circuit 46, and an additional circuit 48.

Referring to FIG. 9 together with FIG. 10, the power supply line 122 (power supply line 12) has a first connection point (connection point) 142, a second connection point (connection point) 144, and a third connection point (connection point) 146. , And a fourth connection point (connection point) 148. The four connection points 142, 144, 146, and 148 are arranged in this order from the connection point 142 closest to the power supply 20 to the connection point 148 closest to the switch circuit 50.

The capacitor 32 is connected to the power supply line 12 at the connection point 142. Specifically, one end of the capacitor 32 is connected to the connection point 142, and the other end of the capacitor 32 is grounded.

The voltage detection circuit 44 is connected to the power supply line 12 at the connection point 144. Specifically, the voltage detection circuit 44 has a detection input end 442, a reference output end 446, and a detection output end 448. The detection input end 442 is connected to the power supply line 12 at the connection point 144, whereby the supply voltage Vin is applied to the detection input end 442. The reference output end 446 outputs the reference voltage Vr according to the applied supply voltage Vin. The detection output terminal 448 outputs the detection voltage Vd according to the applied supply voltage Vin.

The reference output terminal 446 outputs the supply voltage Vin when the supply voltage Vin applied to the detection input terminal 442 is lower than the reference voltage VZ, and outputs the reference voltage VZ when the supply voltage Vin is equal to or higher than the reference voltage VZ. .. Further, the detection output terminal 448 outputs a voltage obtained by dividing the supply voltage Vin as the detection voltage Vd. That is, the detection voltage Vd changes according to the supply voltage Vin and is lower than the supply voltage Vin.

The comparison circuit 46 includes a comparator 46C and a hysteresis circuit 46H including resistors R5 and R6. The comparison circuit 46 (comparator 46C) is connected to the power supply line 12 at the connection point 146, whereby the supply voltage Vin is applied to the comparison circuit 46 (comparator 46C). The comparison circuit 46 (comparator 46C) has a positive input end 462, a negative input end 464, and an output end 468. The positive input end 462 is connected to the reference output end 446 of the voltage detection circuit 44, and a non-inverting voltage Vp corresponding to the reference voltage Vr is applied. The negative input end 464 is connected to the detection output end 448 of the voltage detection circuit 44, and an inverting voltage Vn corresponding to the detection voltage Vd is applied.

The comparison circuit 46 (comparator 46C) compares the non-inverting voltage Vp with the inverting voltage Vn, and outputs an additional control voltage Vca based on the comparison result from the output terminal 468. The additional control voltage Vca is a high voltage corresponding to the supply voltage Vin when the non-inverting voltage Vp is higher than the inverting voltage Vn, and is a low voltage corresponding to the ground voltage when the non-inverting voltage Vp is lower than the inverting voltage Vn. It is a voltage.

The additional circuit 48 has a power supply end 482, a ground end 484, an additional input end 486, a switch control end 488, and a resistor R4. The power supply end 482 is connected to the power supply line 12 at the connection point 148, whereby a voltage corresponding to the supply voltage Vin is applied to the power supply end 482. Specifically, a voltage obtained by dividing the supply voltage Vin by the resistors R4 and (R5 + R6 + R9) is applied to the power supply end 482. The ground end 484 is grounded. The additional input terminal 486 is connected to the output terminal 468 of the comparison circuit 46, and an additional applied voltage Vxa corresponding to the additional control voltage Vca is applied. The switch control end 488 is connected between the power supply end 482 and the connection point 148. The additional circuit 48 operates by the additional applied voltage Vxa and outputs the control voltage Vc from the switch control terminal 488.

The additional circuit 48 is in a non-ground state in which the power supply end 482 and the ground end 484 are cut off by the additional applied voltage Vxa applied to the additional input end 486 according to the additional control voltage Vca, and the power supply end. It is possible to make a transition between the ground state in which the 482 is conducted to conduct the ground end 484 and is grounded. When the additional circuit 48 is in the non-ground state, the switch control end 488 outputs a high voltage corresponding to the supply voltage Vin. On the other hand, when the additional circuit 48 is in the ground state, the switch control end 488 is grounded and outputs a ground voltage (low voltage). That is, the control voltage Vc is a high voltage corresponding to the supply voltage Vin when the additional circuit 48 is in the non-ground state, and is a low voltage corresponding to the ground voltage when the additional circuit 48 is in the ground state. ..

The additional circuit 48 configured as described above can be set so as to make a state transition depending on the magnitude relationship between the additional applied voltage Vxa and a predetermined voltage value (additional threshold value TA). In the present embodiment, the additional threshold TA is set to be lower than the reference voltage VZ. The additional circuit 48 takes a non-ground state until the supply voltage Vin rises from zero and the additional applied voltage Vxa reaches the additional threshold TA. The additional circuit 48 has a magnitude relationship between the additional applied voltage Vxa and the additional threshold TA after the supply voltage Vin rises from zero and the additional applied voltage Vxa first reaches the additional threshold TA. The state is changed accordingly. More specifically, the additional circuit 48 takes a ground state when the additional applied voltage Vxa is higher than the additional threshold TA, and a non-ground state when the additional applied voltage Vxa is lower than the additional threshold TA. I take the.

In the present embodiment, the power supply end 482 is connected between the detection output end 448 of the voltage detection circuit 44 and the switch end 56 of the switch circuit 50. That is, the power supply end 482 is connected to the power supply line 12 and the detection output terminal 448, and according to this configuration, a voltage corresponding to the detection voltage Vd is applied to the power supply end 482. According to the present embodiment, when the additional circuit 48 is in the non-ground state, the switch control terminal 488 has a high voltage corresponding to the detection voltage Vd (a voltage lower than the supply voltage Vin and higher than the detection voltage Vd). Is output. The control voltage Vc in the present embodiment is a high voltage corresponding to the detection voltage Vd when the additional circuit 48 is in the non-ground state, and is a low voltage corresponding to the ground voltage when the additional circuit 48 is in the ground state. It is a voltage. However, the present invention is not limited to this, and the power supply end 482 may be connected to the detection output end 448 if necessary.

The switch end 56 of the switch circuit 50 is connected to the switch control end 488 of the additional circuit 48, and an applied voltage Vx corresponding to the control voltage Vc is applied. The switch circuit 50 can transition between the cutoff state and the conduction state by the applied voltage Vx applied to the switch end 56 according to the control voltage Vc. Specifically, the switch circuit 50 takes a cutoff state until the supply voltage Vin rises from zero and the applied voltage Vx reaches a predetermined threshold value TP. After the supply voltage Vin rises from zero and the applied voltage Vx first reaches the predetermined threshold value TP, the switch circuit 50 changes the state according to the magnitude relationship between the applied voltage Vx and the predetermined threshold value TP. More specifically, the switch circuit 50 takes a conductive state when the applied voltage Vx is higher than the predetermined threshold TP, and takes a cutoff state when the applied voltage Vx is lower than the predetermined threshold TP.

As can be understood from FIGS. 9 and 10, the predetermined threshold value TP, the additional threshold value TA, the additional applied voltage Vxa, and the applied voltage Vx can be adjusted according to the circuit structure of the power storage circuit 30. According to the present embodiment, the applied voltage Vx is lower than the predetermined threshold TP until the supply voltage Vin rises from zero and the additional applied voltage Vxa reaches the additional threshold TA. That is, the additional circuit 48 transitions from the non-ground state to the ground state before the applied voltage Vx reaches the predetermined threshold value TP, whereby a low voltage corresponding to the ground voltage is applied to the switch circuit 50. As a result, the switch circuit 50 maintains the cutoff state even after the additional circuit 48 transitions to the ground state. In particular, according to the present embodiment, the predetermined threshold value TP is equal to or higher than the additional threshold value TA, and it is easy to maintain the cutoff state of the switch circuit 50. However, the present invention is not limited to this, and the predetermined threshold value TP may be smaller than the additional threshold value TA.

Hereinafter, the operation of the power storage circuit 30 configured as described above will be described in detail.

With reference to FIGS. 9 and 11, the capacitor 32 is empty at the time when the power storage circuit 30 starts operating (zero time when the value on the time axis of FIG. 11 is 0). Therefore, each of the supply voltage Vin, the additional control voltage Vca (= additional applied voltage Vxa), and the control voltage Vc (= applied voltage Vx) is 0V. As a result, the additional circuit 48 is in a non-grounded state, blocking between the power supply end 482 and the ground end 484. Similarly, the switch circuit 50 is in a cutoff state, cutting off between the capacitor 32 and the load 60. Further, the power storage circuit 30 is in the initial state.

When the power storage circuit 30 starts operating, the capacitor 32 is gradually charged, whereby the supply voltage Vin is gradually increased. The additional circuit 48 maintains the non-ground state and the switch circuit 50 maintains the cutoff state until the power storage circuit 30 starts operation and reaches a predetermined T0 time. On the other hand, the additional control voltage Vca reaches the additional threshold TA of the additional circuit 48 at T0 time before the control voltage Vc reaches the predetermined threshold TP of the switch circuit 50.

After the additional control voltage Vca reaches the additional threshold TA at T0 time, the supply voltage Vin continues to rise. As a result, the additional control voltage Vca continues to rise beyond the additional threshold TA of the additional circuit 48, and the additional circuit 48 goes into the ground state immediately after T0 hours. When the additional circuit 48 is in the ground state, the control voltage Vc becomes the ground voltage (0V). As a result, the switch circuit 50 maintains the cutoff state, and the capacitor 32 continues to be charged.

The supply voltage Vin continues to rise even after T0 hours. As mentioned above, the reference voltage VZ is higher than the additional threshold TA. With this setting, the supply voltage Vin reaches the reference voltage VZ in T1 time after T0 time, and at this time, the reference voltage Vr (non-inverting voltage Vp) becomes the reference voltage VZ.

The supply voltage Vin continues to rise even after T1 hour, whereby the detection voltage Vd and the inverting voltage Vn continue to rise. On the other hand, the non-inverting voltage Vp is maintained at the reference voltage VZ. As a result, the inverting voltage Vn becomes equal to the non-inverting voltage Vp in a predetermined T2 time, and then exceeds the non-inverting voltage Vp. At T2 hours, the supply voltage Vin reaches the starting voltage VH. Power continues to be stored in the capacitor 32 from T0 hours to T2 hours.

After T2 hours, the non-inverting voltage Vp becomes lower than the inverting voltage Vn, whereby the additional control voltage Vca of the comparison circuit 46 becomes the ground voltage (0V). As a result, the additional circuit 48 is in the non-ground state, and the switch circuit 50 is in the conductive state. In the conductive state, the electric power generated by the power source 20 is supplied to the load 60 together with the electric power stored in the capacitor 32.

As described above, the power storage circuit 30 of the present embodiment continues to accumulate power until the supply voltage Vin reaches a start voltage VH higher than the operation start voltage VS of the load 60, and the supply voltage Vin becomes the start voltage VH. When it reaches, power is supplied to the load 60. That is, the power storage circuit 30 of the present embodiment can stably supply electric power to the load 60.

The power storage circuit 30 of the present embodiment can be configured as shown in FIG. 10, for example.

Referring to FIG. 10, the voltage detection circuit 44 includes three resistors R7, R8, R9 and one constant voltage element (Zener diode) Z1. According to the voltage detection circuit 44, the reference voltage VZ is the Zener voltage of the Zener diode Z1.

The comparator 46C of the comparison circuit 46 includes three switching elements (first switching element 46F, second switching element 46S, and third switching element 46T) and three resistors R1, R2, and R3. Each of the first switching element 46F and the second switching element 46S is composed of a P-type MOSFET, and the third switching element 46T is composed of an N-type MOSFET. Each switching element is capable of transitioning between an ON state in which the source and the drain are conductive and an OFF state in which the source and the drain are cut off, depending on the voltage applied to the gate.

When the power storage circuit 30 is in the steady state, if the inverting voltage Vn is lower than the non-inverting voltage Vp, the first switching element 46F is turned on and the second switching element 46S is turned off. As a result, a ground voltage is applied to the gate of the third switching element 46T, and the third switching element 46T is turned off. That is, the drain (output end 468) of the third switching element 46T is cut off from the ground, and the output end 468 outputs a high voltage (supply voltage Vin).

On the other hand, when the power storage circuit 30 is in the steady state and the inverting voltage Vn exceeds the non-inverting voltage Vp, the first switching element 46F is turned off and the second switching element 46S is turned on. As a result, a voltage obtained by dividing the supply voltage Vin by the resistor R2 and the resistor R1 is applied to the gate of the third switching element 46T, and the third switching element 46T is turned on. That is, the drain (output end 468) of the third switching element 46T conducts with the ground, and the output end 468 outputs a low voltage (ground voltage).

The additional circuit 48 includes an additional switching element 48A made of an N-type MOSFET in addition to the resistor R4. In the additional switching element 48A, the gate functions as an additional input end 486, the source functions as a ground end 484, and the drain functions as a power supply end 482. The additional switching element 48A is composed of an N-type MOSFET, and has an ON state in which the source and the drain are conductive and an OFF state in which the source and the drain are cut off, depending on the voltage applied to the gate. It is possible to transition between. The additional circuit 48 configured as described above takes a non-ground state until the supply voltage Vin rises from zero and the additional applied voltage Vxa reaches the additional threshold TA. In the present embodiment, the additional threshold TA is the gate threshold of the additional switching element 48A. The reference voltage VZ of the constant voltage element Z1 in the present embodiment is sufficiently higher than the additional threshold value TA.

The switch circuit 50 includes two switching elements (main switching element 50M and sub-switching element 50S) and three resistors R11, R12, and R13. The main switching element 50M is composed of a P-type MOSFET, and the sub-switching element 50S is composed of an N-type MOSFET. Each switching element is capable of transitioning between an ON state in which the source and the drain are conductive and an OFF state in which the source and the drain are cut off, depending on the voltage applied to the gate.

In the main switching element 50M, the source is connected to the power supply 20 side (power supply line 122) of the power supply line 12, and the drain is connected to the load 60 side (power supply line 126) of the power supply line 12. The gate of the sub-switching element 50S is connected to the switch control end 488 of the additional circuit 48 via the resistor R11 and functions as the switch end 56. In the sub-switching element 50S, the source is grounded and the drain is connected to the source of the main switching element 50M via two resistors R12 and R13. The gate of the main switching element 50M is connected between the two resistors R12 and R13.

The switch circuit 50 configured as described above takes a cutoff state until the supply voltage Vin rises from zero and the applied voltage Vx reaches a predetermined threshold value TP. In the present embodiment, the predetermined threshold value TP is the gate threshold value of the sub-switching element 50S. The reference voltage VZ of the constant voltage element Z1 in the present embodiment is sufficiently higher than the predetermined threshold value TP.

In the simulator, the power storage circuit 30 shown in FIG. 10 was constructed as the circuit of the embodiment, and the operation was verified. Table 1 shows the capacitance value, resistance value, etc. of each element in the circuit of the embodiment.

Based on the resistance values shown in Table 1, the start voltage VH, the stop voltage VL, and the combined resistance R of the power storage circuit 30 were calculated. In this calculation, the influence of switching elements was not considered. As a result of the calculation, the starting voltage VH was 4.5V and the stopping voltage VL was 1.3V. The gate threshold VGS (th) of each switching element was lower than the calculated stop voltage VL. The combined resistance R is 33 kΩ until the supply voltage Vi drops from the start voltage VH to the stop voltage VL, and 33 kΩ until the supply voltage Vi rises from the stop voltage VL to the start voltage VH. was.

The circuit of the example was connected between the power source 20 and the load 60, and the operation of the circuit of the example was verified. In the operation verification, eight photovoltaic cells connected in series were used as the power source 20, and a 10Ω resistor was used as the load 60. In each of the photovoltaic cells, the light receiving area was 57.8 cm ² , the open circuit voltage Voc due to direct sunlight was 1 V, and the short-circuit current Isc due to direct sunlight was 500 mA. Light having a spectrum equivalent to sunlight was applied at an intensity of 10 mW / cm ² from vertically above the photovoltaic cell, whereby a current of about 50 mA was supplied from the power source 20 to the circuit of the example. The Zener voltage VZ (nominal value: 1.8V) of the Zener diode Z1 depends on the current value supplied from the power supply 20, and was 0.9V under the above conditions. Under the above conditions, the supply voltage Vin, the reference voltage Vr (non-inverting voltage Vp), and the detection voltage Vd are set to the starting point (at 0 seconds) when the capacitor 32 is empty (that is, the voltage of the capacitor 32 is 0 V). , The inverting voltage Vn, the control voltage Vc, and the output voltage Vout were measured by a simulator.

FIG. 12 shows the measurement results. As can be seen from FIG. 12, the circuit of the embodiment can stably supply power to the load 60.

In a power storage system equipped with a power supply, a power storage circuit, and various loads, by applying energy harvesting as a power source for operating the load, a battery becomes unnecessary, which makes the power storage system lighter and more expensive. Various effects such as environment resistance and maintenance-free can be expected. As an application example of the power storage type system, a sensor system equipped with a sensor as a load can be considered. Various sensor systems, particularly wireless sensor systems, are indispensable for grasping the state of industrial equipment (electronic equipment) in the IoT field and the M2M field, which have been rapidly developing in recent years.

When grasping the state of industrial equipment by a sensor system applying energy harvesting, it is necessary to connect some signal line output from the industrial equipment to the sensor system. On the other hand, the power storage circuit in such a sensor system intermittently operates the sensor system with a minute amount of electric power obtained by energy harvesting. Various problems can occur if a current flows through the signal line to the sensor when the power storage circuit is not supplying power to the sensor. For example, expensive industrial equipment may break down. Such a problem has been one of the reasons why energy harvesting has not been put into practical use.

On the other hand, according to the present invention, no current flows through the signal line of the sensor. Therefore, a sensor system to which energy harvesting is applied can exert its original effect. In addition, the sensor can be safely connected to expensive industrial equipment. According to the present invention, it is considered that the application of energy harvesting in the IoT field and the M2M field is promoted.

10 Power storage system 12 Power supply line 122 Input side power supply line (power supply line)
126 Output side power supply line (power supply line)
142 First connection point (connection point)
144 Second connection point (connection point)
146 Third connection point (connection point)
148 4th connection point (connection point)
162, 162A Detection point 20 Power supply 30 Power storage circuit 32 Capacitor (power storage unit)
40 Control unit 44 Voltage detection circuit 442 Detection input end 446 Reference output end 448 Detection output end 46 Comparison circuit 46C Comparator 46H Hysteresis circuit 46F 1st switching element 46S 2nd switching element 46T 3rd switching element 462 Positive input end 464 Negative input end 468 Output end 48 Additional circuit 48A Additional switching element 482 Power supply end 484 Ground end 486 Additional input end 488 Switch control end 50 Switch circuit (switch section)
50M Main switching element 50S Sub switching element 56 Switch end 60 Load 62 Load (sensor)
622 Measuring end 64 Load (DC-DC converter)
66 Load (microcomputer)
668 Control end 70, 70A Breaking circuit 702 1st element 704 2nd element 72 Input end 74 Power supply detection end 78 Output end R7, R8, R9 Resistance (voltage detection circuit resistance)
R1, R2, R3 resistors (comparator resistors)
R5, R6 resistance (hysteresis circuit resistance)
R4 resistor (resistor of additional circuit)
R11, R12, R13 resistors (switch circuit resistors)
R61, R62 resistance (sensor resistance)
R64 resistor (DC / DC converter resistor)
R71, R72, R73 resistance (resistor of break circuit)
R74, R75 resistors (resistors of the break circuit in the modified example)
Z1 constant voltage element (Zener diode)
Vin supply voltage Vout output voltage VZ reference voltage Vr reference voltage Vd detection voltage Vp non-inverting voltage Vn inverting voltage Vca additional control voltage Vxa additional applied voltage Vc control voltage Vx applied voltage VS operation start voltage VH start voltage VL stop voltage Vxin measurement Voltage Vxout Measured voltage Vxd Detected voltage VP Predetermined voltage

Claims (4)

A breaking circuit having an input end, an output end, and a power supply detection end.
The output end of the break circuit is connected to a load operated by electric power supplied from the power storage circuit.
When the voltage applied to the power supply detection end is equal to or less than a predetermined voltage, the output end is cut off from the input end, while when the voltage applied to the power supply detection end is larger than the predetermined voltage, the output end is cut off. A cutoff circuit that conducts the input end. The break circuit according to claim 1.
The power storage circuit is a circuit that stores electric power supplied from a power source and supplies it to the load.
The power storage circuit includes a power supply line, a power storage unit, and a control unit.
The power supply line connects the power supply and the load to each other.
The power storage unit is connected to the power supply line, accumulates the power supplied from the power supply, and applies a supply voltage larger than zero to the power supply line.
The control unit cuts off the load from the power storage unit until the supply voltage starts from zero and reaches the start voltage.
After the supply voltage reaches the start voltage, the control unit conducts the load with the power storage unit until the supply voltage drops to the stop voltage, and when the supply voltage drops to the stop voltage, the control unit causes the load. The load is cut off from the power storage unit until the supply voltage reaches the start voltage again.
The power supply detection end of the cutoff circuit is a cutoff circuit that is directly or indirectly connected to a detection point on the power supply line. The break circuit according to claim 2.
The voltage at the detection point is a ground voltage when the load is cut off from the power storage unit, and is a voltage higher than the ground voltage when the load is conducting with the power storage unit. The break circuit according to claim 2 or 3.
The power storage circuit includes a switch unit.
The switch unit is connected between the power storage unit and the load in the power supply line.
The switch portion has a switch end and has a switch end.
When the voltage applied to the switch end is lower than the predetermined threshold value, the switch unit takes a cutoff state in which the load is cut off from the power storage unit, and the voltage applied to the switch end is higher than the predetermined threshold value. In the case, a conductive state is taken in which the load is made conductive with the power storage unit.
The control unit is connected between the power storage unit and the switch unit in the power supply line.
The control unit applies a voltage lower than the predetermined threshold value to the switch end until the supply voltage starts from zero and reaches the start voltage.
After the supply voltage reaches the start voltage, the control unit applies a voltage higher than the predetermined threshold voltage to the switch end until the supply voltage drops to the stop voltage, and the supply voltage becomes the supply voltage. A cutoff circuit that applies a voltage lower than the predetermined threshold voltage to the switch end until the supply voltage reaches the start voltage again when the voltage drops to the stop voltage.

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