JP2006158043A - Power controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power controller for achieving an output voltage quickly rising at a start of charging, eliminating a drastic fluctuation in the output voltage and enabling a high-capacity charge. <P>SOLUTION: A power controller is provided with an initial storage apparatus 21 connected to an input/output node 16b and storing a current inputted to the input/output node 16b, a backup storage apparatus 22 connected to the input/output node 16b through a variable conductance element 23 and storing the current inputted to the input/output node 16b, and a storage controlling circuit 13 for controlling a conductance of the variable conductance element 23 in accordance with a conductance change characteristic for monotonically increasing relative to a voltage difference between the output voltage and a threshold voltage if the output voltage from the input/output node 16b exceeds the fixed threshold voltage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power control device that stores power generated by a power generation element and outputs a voltage, and in particular, power control that has excellent rising characteristics and stability of an output voltage at the start of power storage and enables large-capacity charging. Relates to the device.

  In many technical fields such as logistics management, facility management, or acquisition of ever-changing environmental information, such as vibration detection due to wear on automobile and railway vehicle bearings, heat detection in fire alarm systems, etc., the physical quantity of the measurement target is measured with sensors. A wireless sensor that transmits the measurement result to the outside by radio is used. Such a wireless sensor requires a power supply means for driving without receiving power from the power line from the outside. Many wireless sensors are installed in the environment or installed in places where people are difficult to enter. Therefore, it is desirable that the power supply of the wireless sensor is as self-contained as possible. Therefore, as a power supply method, a self-power generation method in which a power generation element is provided in the sensor node and electric power generated in the power generation element is used as a power source is excellent (see Patent Documents 1 to 5).

  In recent years, a self-power generation type electronic timepiece has been developed in which a power generation element is provided in a timepiece and an electronic circuit in the timepiece is driven by electric power generated by the power generation element (see Patent Documents 6 and 7).

  These self-powered electronic devices require a power control device that stores the power generated by the power generation element and generates a constant power supply voltage for driving the electronic circuit from the stored power.

  FIG. 13 is a diagram illustrating a configuration of the power control device described in Patent Document 6. In FIG. 13, the electronic device 100 includes a solar cell 101, a power control device 102, and a load device 103. The solar cell 101 is a power generation element that converts light energy into current. The power control device 102 is a device that stores the current output from the solar battery 101 and outputs the stored power as a voltage. The load device 103 is a device driven by a voltage output from the power control device 102.

  The power control device 102 includes a power storage device 104, a supply unit 105, a control circuit 106, an auxiliary power storage device 107, a limit switch 108, a discharge switch 109, and backflow prevention diodes 110 and 111.

  The power storage device 104 stores the current output from the solar battery 101. Supply unit 105 disconnects current flowing from the power generation element into power storage device 104. The supply unit 105 includes a constant voltage unit 112 including two diodes 112a and 112b connected in series, a bypass switch 113a connected in parallel to the diode 112a, and a bypass switch 113b connected in parallel to the diode 112b. A bypass unit 113 is provided.

  The auxiliary power storage device 107 is connected to both electrodes of the solar cell 101 and stores the current output from the solar cell 101. The limit switch 108 discharges between the output terminals 102a and 102b so that the voltage between the output terminals 102a and 102b of the power control apparatus 102 does not exceed a certain value. The discharge switch 109 is a switch that disconnects discharge from the power storage device 104 to the output terminal of the power control device 102. The backflow prevention diodes 110 and 111 are diodes for preventing a reverse current from flowing through the solar cell 101.

  The control circuit 106 controls disconnection of the bypass switches 113a and 113b, the limit switch 108, and the discharge switch 109 based on the voltage between the output terminals 102a and 102b of the power control device 102 and the voltage between both electrodes of the power storage device 104. Do.

  In FIG. 13, the bypass switches 113a and 113b and the limit switch 108 are constituted by p-channel MOS transistors, and the discharge switch 109 is constituted by an n-channel MOS transistor.

  Next, the operation of the conventional power control apparatus 102 configured as described above will be described. FIG. 14 is a timing chart of the power control apparatus 102 shown in FIG.

At time _{t 0,} almost charges are not stored in the power storage device 104, the state of the charging voltage _{V SC} approximately 0V. At this time, the control signals φ ₁ , φ ₂ , and φ ₄ output from the control circuit 106 to the bypass switches 113 a and 113 b and the limit switch 108 are at the L level, and the control signal φ ₃ output to the discharge switch 109 is at the H level. is there. Therefore, each switch is in an off state. In this state, when the solar cell 101 is irradiated with light, the power supplied from the solar cell 101 is supplied to the constant voltage unit 112 and the power storage device 104 by the supply unit 105. In the supply unit 105 includes a diode 112a, a voltage drop occurs by the forward bias voltage _{V F} of 112b, the supply voltage _{V SCP} of the power storage device 104 is increased.

At time t _1, when the supply voltage V _SCP passes the reference voltage V0 in the increasing direction, V0 + detection signal in the control circuit 106 becomes H level, the state for detecting the reference voltage V1 to be described later. In addition, the V0− detection signal in the control circuit 106 becomes H level, and V0− described later can be detected. Further, when the supply voltage V _SCP passes the reference voltage V0, the reset detection signal becomes L level.

  At this time, the same voltage as that of the supply unit 105 is applied to the auxiliary power storage device 107 connected in parallel with the supply unit 105, and electric power is stored in the auxiliary power storage device 107. With this electric power, the load device 103 can be activated.

  Even when the illuminance is low and only a small current is supplied from the solar battery 101, a predetermined voltage is established in the supply unit 105 by the forward bias voltage of the constant voltage unit 112, and the voltage also appears in the auxiliary power storage device 107. Therefore, even in such a case, a voltage necessary for starting the load device 103 can be secured immediately, and the load device 103 can be started quickly.

When power supply from the solar battery 101 is continuously performed, the power storage device 104 is charged, and the charging voltage _VSC increases. The charge voltage _{V SC} at time _{t 2} reaches the reference voltage V1 (0.6V), the control circuit 106 a control signal phi ₁ and H level, the bypass switch 113a is turned on. As a result, the diode 112a is bypassed by the bypass switch 113a, and the voltage drop in the constant voltage unit 112 is halved. Along with this, although the output voltage V _SS current flows in the power storage device 104 from the auxiliary power storage device 107 decreases rapidly, since sufficient charging voltage V _SC is established in the power storage device 104, an output voltage V _SS does not drop below the minimum voltage required for operation of the load device 103. Subsequently, a current is supplied from the solar cell 101 to the power storage device 104, and the supply voltage _VSCP increases.

The charge voltage _{V SC} at time _{t 3} reaches the reference voltage V2 (1.2V), the control circuit 106 a control signal phi ₂ to the H level, the bypass switch 113b is turned on. As a result, the diodes 112a and 112b are bypassed by the bypass switch 113b, and the output of the solar cell 101 is directly supplied to the power storage device 104. Also, along with this, although the output voltage V _SS current flows in the power storage device 104 from the auxiliary power storage device 107 decreases rapidly, since sufficient charging voltage V _SC is established in the power storage device 104, the output voltage V _SS is the lowest voltage does not decrease until the following required for the operation of the load device 103.

Further, the control signal phi ₃ and L level at the same time, the discharge switch 109 in the ON state. Accordingly, when there is no output from the solar battery, power is supplied from the power storage device 104 to the auxiliary power storage device 107.
JP 2003-262645 A JP 2003-168182 A JP 2003-22492 A JP 2003-307228 A JP 2000-222668 A JP-A-9-264971 Japanese Patent Laid-Open No. 11-14766

Above in the conventional power control device 102, upon exceeding the threshold voltage V1, V2 with the charging voltage _{V SC,} respectively bypass switches 113a, 113b stepwise the ON state. At this time, the voltage drop of the supply unit 105 changes rapidly, the charge transfer to the power storage device 104 from the auxiliary power storage device 107 occurs, a sudden drop in the output voltage V _SS is generated. Sharp drop in such an output voltage V _SS becomes a power supply noise to the load device 103, which may adversely affect the operation of the load device 103.

In power control device 102, although the voltage applied to power storage device 104 is set low by diodes 112a and 112b, charging current always flows into both auxiliary power storage device 107 and power storage device 104 during charging. Therefore, the time from when charging is started until auxiliary power storage device 107 is fully charged is delayed. That is, the output voltage V _SS rise time is long (t ₀ ~t ₄ or the like in FIG. 14), the load device 103 recovery time interval (power supply voltage until the next re-power from the power consumption ) Is required to be relatively long. Therefore, the power control apparatus 102 is not suitable for application to a load apparatus that frequently consumes power at short intervals.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a power control apparatus in which the output voltage rises quickly at the start of power storage, there is no sudden fluctuation in the output voltage, and large capacity charging is possible.

A first configuration of a power control device according to the present invention is a power control device that stores a direct current or a pulsating current input to an input / output node and outputs a voltage to the input / output node,
An initial power storage device that is connected to the input / output node and stores a current input to the input / output node;
Variable conductance element with variable conductance;
One or more backup power storage devices that are connected to the input / output node via the variable conductance element and store a current input to the input / output node;
In addition, when the voltage of the input / output node (hereinafter referred to as “output voltage”) exceeds a certain threshold voltage, the variable conductance according to a conductance change characteristic that monotonously increases with respect to a difference voltage between the output voltage and the threshold voltage. A storage control circuit for controlling the conductance of the element;
It is characterized by having.

  According to this configuration, at the start of power storage, the current input to the input / output node is stored in the initial power storage device, and the voltage of the input / output node (output voltage) increases accordingly. When the output voltage exceeds the threshold voltage, the power storage control circuit controls the conductance of the variable conductance element according to the conductance change characteristic that monotonously increases with respect to the difference voltage between the output voltage and the threshold voltage. That is, the conductance of the variable conductance element is controlled such that when the difference voltage is negative, the conductance of the variable conductance element is 0, and when the difference voltage exceeds 0 and becomes positive, the conductance of the variable conductance element suddenly increases monotonously. . For this reason, even immediately after the output voltage exceeds the threshold voltage, the output voltage is held at the threshold value or more, and the occurrence of noise that causes the output voltage to drop rapidly is suppressed.

  Here, a capacitor or a secondary battery can be used as the initial power storage device and the backup power storage device.

  In the present invention, the electrostatic capacity of the initial power storage device can be reduced, and the electrostatic capacity of the backup power storage device can be made larger than that of the initial power storage device. As a result, at the start of power storage, power is stored in the small-capacity initial power storage device, so that the rise of the input / output node is accelerated. Further, after the voltage of the input / output node reaches a predetermined threshold voltage, the current input to the input / output node is stored in the backup power storage device having a large capacitance. Therefore, even when power is extracted from the input / output node and consumed, the voltage drop at the input / output node can be delayed by the charge stored in the backup power storage device.

  According to a second configuration of the power control device of the present invention, in the first configuration, the initial power storage device is connected to the input / output node in parallel with the backup power storage device and the variable conductance element. It is characterized by that.

  According to this configuration, at the start of power storage, the current input to the input / output node is stored in the initial power storage device, and the voltage of the input / output node (output voltage) increases accordingly. When the output voltage exceeds the threshold voltage, the power storage control circuit controls the conductance of the variable conductance element according to the conductance change characteristic that monotonously increases with respect to the difference voltage between the output voltage and the threshold voltage. As a result, while the power stored in the initial power storage device is not consumed, the current input to the input / output node flows into the backup power storage device connected in parallel to the initial power storage device and is stored. The bipolar voltage of the power storage device for use increases. Therefore, the current input to the input / output node can be stored in the backup power storage device without waste.

Note that when a plurality of backup power storage devices are used, a configuration in which the initial power storage devices are simply connected in parallel may be used, or a connection as illustrated in FIG. That is, the initial power storage device C ₁ , N (N ≧ 2) variable conductance elements VG _i (i = 1,..., N), N backup power storage devices C _{2, i} (i = 1,..., N) ) And N power storage control circuits CNT _i (i = 1,..., N). Then, to connect in parallel the i-th variable conductance element VG _i and i th of N circuit and a power storage device C _{2, i} are connected in series for backup to the initial power storage device C _1. The power storage control circuit CNT _i controls the conductance of the variable conductance element VG _i . Further, the power storage control circuit CNT ₁ is, when the output voltage _{V out} exceeds a certain threshold voltage _{V full,} variable conductance element according conductance change characteristics that increase monotonically with respect to the difference voltage between the output voltage _{V out} and the threshold voltage _{V full} The conductance of VG ₁ is controlled, and the power storage control circuit CNT _i (i ≧ 2) is configured such that when the voltages V _{2 and i−1} of the backup power storage devices C _{2 and i−1} exceed the threshold voltage V _full , The conductance of the variable conductance element VG _i is controlled according to the conductance change characteristic that monotonously increases with respect to the difference voltage between the voltages V _{2 and i−1} and the threshold voltage V _full . As described above, by increasing the number of backup power storage devices, it is possible to charge a larger capacity while maintaining a short rise time of the output voltage at the start of power storage.

  According to a third configuration of the power control device of the present invention, in the first configuration, the backup power storage device has a larger capacitance than the initial power storage device, and the initial power storage device is the variable It is characterized by being connected in parallel with a conductance element and in series with the backup power storage device.

  According to this configuration, at the start of power storage, the current input to the input / output node is stored in the initial power storage device, and the voltage of the input / output node (output voltage) increases accordingly. When the output voltage exceeds the threshold voltage, the power storage control circuit controls the conductance of the variable conductance element according to the conductance change characteristic that monotonously increases with respect to the difference voltage between the output voltage and the threshold voltage. Thereby, the current flowing into the input / output node is stored in the backup power storage device, and the charge stored in the initial power storage device is gradually discharged. Therefore, while the output voltage is maintained at a constant threshold voltage, the voltage between both electrodes of the initial power storage device decreases and the voltage across the backup power storage device increases.

Thereby, immediately after the start of power storage, power is stored in the initial power storage device and the backup power storage device. Assume that the capacitance of the initial power storage device is C ₁ , the capacitance of the backup power storage device is C _{2, i} (i = 1,..., N: N is the number of backup power storage devices), and the output voltage is V _out. The electric charge Q stored in the initial power storage device and the backup power storage device connected in series is expressed by the equation (1), and the voltages V ₁ and V ₂ between the electrodes of the initial power storage device and the backup power storage device are expressed by the formula (1) 2) where V ₁ > V ₂ . Here, it is assumed that the plurality of backup power storage devices are simply connected in parallel.

In this case, since the capacitance of the series-connected initial power storage device and the backup power storage device is smaller than the capacitance C ₂ of the backup power storage device alone, the output voltage rises to the threshold voltage in an early stage. Therefore, the speed at which the output voltage decreases is fast.

On the other hand, after the output voltage rises to the threshold voltage, the initial power storage device with a small capacitance is gradually discharged and the backup power storage device with a large capacitance is gradually charged. As a result, the ratio of the voltage between both electrodes of the backup power storage device with respect to the output voltage V _out gradually increases and the ratio of the voltage between both electrodes of the initial power storage device gradually decreases, and finally V ₁ = 0, V ₂ = The battery is charged until it reaches V _out . Therefore, the amount of charge finally stored is Q = C ₂ V. As a result, the time for the output voltage to rise to the threshold voltage in the initial stage of power storage can be shortened. Can be suppressed.

Although a case where a plurality of backup power storage devices are simply connected in parallel has been described here, a plurality of backup power storage devices are connected in series as shown in FIG. You can also. That is, the initial power storage device C ₁ , N (N ≧ 2) variable conductance elements VG _i (i = 1,..., N), N backup power storage devices C _{2, i} (i = 1,..., N) ) And N power storage control circuits CNT _i (i = 1,..., N). Then, the initial power storage device C ₁ and each backup power storage device C _2,1 ,..., C _{2, N} are connected in series. The power storage control circuit CNT _i controls the conductance of the variable conductance element VG _i . Power storage control circuit CNT ₁ is, when the output voltage _{V out} exceeds a certain threshold voltage _{V full,} variable conductance element according conductance change characteristics that increase monotonically with respect to the difference voltage between the output voltage _{V out} and the threshold voltage _{V full} The conductance of VG ₁ is controlled, and the power storage control circuit CNT _i (i ≧ 2) is configured such that when the voltages V _{2 and i−1} of the backup power storage devices C _{2 and i−1} exceed the threshold voltage V _full , The conductance of the variable conductance element VG _i is controlled according to the conductance change characteristic that monotonously increases with respect to the difference voltage between the voltages V _{2 and i−1} and the threshold voltage V _full . As described above, by increasing the number of backup power storage devices, it is possible to charge a larger capacity while maintaining a short rise time of the output voltage at the start of power storage.

  According to a fourth configuration of the power control apparatus of the present invention, in any one of the first to third configurations, the power control device includes a reference generation circuit that generates a constant reference voltage, and the power storage control circuit outputs the output voltage. When a voltage obtained by voltage division at a certain voltage division ratio (hereinafter referred to as “comparison voltage”) exceeds the reference voltage, a voltage proportional to a difference voltage between the comparison voltage and the reference voltage (hereinafter referred to as “storage control voltage”). The variable conductance element is composed of a field effect transistor whose conductance increases with an increase in the storage control voltage input to the gate terminal.

  According to this configuration, the operational amplifier circuit compares the comparison voltage and the reference voltage, and when the comparison voltage exceeds the reference voltage, outputs an accumulation control voltage proportional to the difference voltage between the two. Here, the voltage dividing ratio is set so that the comparison voltage and the reference voltage match when the output voltage is the threshold voltage. In the field effect transistor that is a variable conductance element, the conductance of the channel increases as the storage control voltage input to the gate increases. As a result, when the output voltage exceeds the threshold voltage, it is possible to control the conductance of the variable conductance element according to a conductance change characteristic that monotonously increases with respect to a difference voltage between the output voltage and the threshold voltage.

  Here, as the reference generation circuit, a band gap circuit that operates according to the voltage of the input / output node can be used. By using the band gap circuit, a stable reference voltage can be obtained regardless of the temperature.

A fifth configuration of the power control apparatus according to the present invention is the charge input switch circuit for intermittently supplying the current input to the input / output node in any one of the first to fourth configurations;
And an overcurrent prevention circuit that disconnects the charge input switch circuit when a voltage between both terminals of the backup power storage device reaches the threshold voltage;
It is characterized by having.

  With this configuration, the overcurrent prevention circuit disconnects the charging input switch circuit when the voltage between both terminals of the backup power storage device reaches the threshold voltage, so that the output voltage exceeds the threshold voltage and excessively rises. Can be prevented.

  As described above, according to the present invention, the power storage device is divided into the initial power storage device and the backup power storage device, and the initial power storage device is preferentially stored immediately after the start of power storage. The voltage rises faster. In addition, even when the initial power storage device is charged and the output voltage rises, and immediately after the output voltage exceeds the threshold voltage, the output voltage is held above the threshold, and noise is generated that causes the output voltage to drop rapidly. It can be suppressed. Therefore, the output voltage is stabilized, and it is possible to supply power with high quality. After the output voltage reaches the threshold voltage, power is stored in the backup power storage device. Therefore, even when power is consumed in a period when the storage capacity is large and there is no input current, the output voltage is set to the predetermined threshold value for a long time. A value close to the voltage can be maintained.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Here, a case where the power control apparatus according to the present invention is applied to a wireless sensor (for example, see Patent Documents 1 to 5) will be described.

  FIG. 2 is a block diagram illustrating the configuration of the wireless sensor and the power control apparatus according to the first embodiment of the present invention. The wireless sensor 1 includes a power generation sensor element 2, a power control device 3, a load circuit 4, and an antenna 5.

  The power generation sensor element 2 is a sensor that detects physical energy as an electrical signal, and can also be used as a power generation element. As the power generation sensor element 2, various sensors such as a piezoelectric sensor, a temperature sensor, and a photoelectric conversion element can be used depending on the purpose. Here, as an example, it is assumed that the power generation sensor element 2 uses a piezoelectric sensor that detects mechanical vibration for machine failure diagnosis and the like.

  The power control device 3 is a device for accumulating the power generated by the power generation sensor element 2 and supplying it to each circuit as drive power for the wireless sensor 1. The load circuit 4 is a circuit that consumes the power supplied by the power control device 3. In this embodiment, the load circuit 4 includes a sensor circuit 4a and a transmission / reception circuit 4b. The sensor circuit 4a is a circuit that inputs an electrical signal output from the power generation sensor element 2 and outputs it as a detection signal. The transmission / reception circuit 4b is a circuit that transmits a detection signal output from the sensor circuit 4a from the antenna 5 according to a predetermined communication protocol and receives various operation commands transmitted from the outside via the antenna 5.

  The power control device 3 includes a rectifier circuit 10, a power storage circuit 11, a reference generation circuit 12, a power storage control circuit 13, an overcharge prevention circuit 14, a charge input switch circuit 14a, a power supply control circuit 15, and a power supply switch circuit 15a. Yes.

  The rectifier circuit 10 is a circuit that rectifies an alternating current output from the power generation sensor element 2. The power storage circuit 11 is a circuit for storing a direct current or pulsating current output from the rectifier circuit 10 and outputting it as a voltage. The reference generation circuit 12 is a circuit that generates and outputs a constant reference voltage, and a bandgap reference circuit is usually used. The power storage control circuit 13 is a circuit for controlling the power storage operation of the power storage circuit 11.

  The overcharge prevention circuit 14 is a circuit that controls connection / disconnection of the charge input switch circuit 14a so that the electric power stored in the power storage circuit 11 does not exceed the allowable capacity. The charging input switch circuit 14 a is provided on a power supply line that connects the rectifier circuit 10 and the storage circuit 11. The power supply control circuit 15 is a circuit that controls power supply from the power storage circuit 11 to the load circuit 4 by performing disconnection control of the power supply switch circuit 15a. The power feeding switch circuit 15 a is provided on a power supply line that connects the output of the power storage circuit 11 and the power input of the load circuit 4.

  FIG. 3 is a diagram illustrating a detailed circuit configuration of the power control device 3 according to the present embodiment. In FIG. 3, the rectifier circuit 10, the storage circuit 11, the storage control circuit 13, the overcharge prevention circuit 14, the charge input switch circuit 14a, the power supply control circuit 15, and the power supply switch circuit 15a are the same as those in FIG. The same reference numerals are given and description thereof is omitted. The reference generation circuit 12 is not shown in FIG.

  The rectifier circuit 10 is configured by a normal diode bridge circuit 20 including four diodes. As a result, the rectifier circuit 10 performs full-wave rectification on the alternating current output by the power generation sensor element 2. Two output lines of the rectifier circuit 10 are connected to the input / output node 16 a and the ground node 17. The input / output node 16a is connected to the input / output node 16b via the charging input switch circuit 14a, and the input / output node 16b is connected to the input / output node 16c via the power supply switch circuit 15a.

  The power storage circuit 11 includes an initial power storage device 21, a backup power storage device 22, and a variable conductance element 23. Initial power storage device 21 is a capacitor connected between input / output node 16 b and ground node 17. Initial power storage device 21 stores a current input from power generation sensor element 2 to input / output node 16b via charge input switch circuit 14a.

  The variable conductance element 23 is composed of a p-channel MOS transistor. The backup power storage device 22 is configured by a capacitor having a larger capacitance than the initial power storage device 21. Variable conductance element 23 and backup power storage device 22 are connected in series between input / output node 16 b and ground node 17. That is, the initial power storage device 21 is connected between the input / output node 16 b and the ground node 17 in parallel with the backup power storage device 22 and the variable conductance element 23.

  The variable conductance element 23 can change the conductance by a voltage input to its gate. The backup power storage device 22 stores the current input from the power generation sensor element 2 to the input / output node 16b via the charge input switch circuit 14a.

  In FIG. 3, the backup power storage device 22 is represented by a single capacitor, but a plurality of capacitors may be connected in parallel. Alternatively, a plurality of backup power storage devices 22 and variable conductance elements 23 may be connected between the input / output node 16 b and the ground node 17.

When the voltage at the input / output node 16b (hereinafter referred to as “output voltage”) V _c1 exceeds a certain threshold voltage V _full , the power storage control circuit 13 determines the difference voltage ΔV = between the output voltage V _c1 and the threshold voltage V _full. This is a circuit that controls the gate voltage of the variable conductance element 23 in accordance with the conductance change characteristic that monotonously increases with respect to V _c1 −V _full .

  The power storage control circuit 13 includes voltage dividing resistors 24, 25, 27, 28, operational amplifiers 26, 29, and a wired NOR circuit 30.

The voltage dividing resistors 24 and 25 are connected in series between the input / output node 16b and the ground node. The voltage dividing resistors 24 and 25 _{divide the} output voltage V _c1 generated at the input / output node 16b at a constant voltage dividing ratio (R _c1h1 : R _c1h2 ), and the comparison voltage V _c1 is connected to the connection node of both the voltage dividing resistors 24 and 25. 'Raise. The voltage dividing resistors 27 and 28 are connected in series between a connection node (hereinafter referred to as “backup output node”) 31 between the backup power storage device 22 and the variable conductance element 23 and a ground node. The voltage dividing resistors 27 and 28 _divide a voltage generated at the backup output node 31 (hereinafter referred to as “backup voltage”) V _c2 at a constant voltage dividing ratio (R _c2h1 : R _c2h2 ), and both the voltage dividing resistors 27 and 28. The comparison voltage V _c2 ′ is generated at the connection node. It is assumed that the voltage dividing ratio of the voltage dividing resistors 24 and 25 and the voltage dividing ratio of the voltage dividing resistors 27 and 28 are equal.

The operational amplifier 26 has two inputs, one of which receives the comparison voltage V _c1 ′ and the other of which receives the reference voltage V _ref output from the reference generation circuit 12. When the comparison voltage V _c1 ′ is higher than the reference voltage V _ref , the operational amplifier 26 outputs a voltage (hereinafter referred to as “storage control voltage”) V _g1 proportional to the difference voltage between the comparison voltage V _c1 ′ and the reference voltage V _ref . To do.

The operational amplifier 29 has two inputs, one of which receives the comparison voltage V _c2 ′ and the other of which receives the comparison voltage V _c1 ′. When the comparison voltage V _c2 ′ is higher than the comparison voltage V _c1 ′, the operational amplifier 29 _generates a voltage (hereinafter referred to as “power supply control voltage”) V _g2 proportional to the difference voltage between the comparison voltage V _c1 ′ and the reference voltage V _ref . Output.

The storage control voltage V _g1 and the power supply control voltage V _g2 are input to the wired NOR circuit 30. The wired NOR circuit 30 outputs a voltage (hereinafter referred to as “conductance control voltage”) V _g obtained by taking the wired NOR between the power storage control voltage V _g1 and the power supply control voltage V _g2 to the gate of the variable conductance element 23.

When the output voltage V _c1 is higher than a predetermined threshold voltage V _full = ((R _c1h1 + R _c1h2 ) V _c1 ′ / R _c1h2 ), the storage control voltage V _g1 is proportional to the difference voltage ΔV = V _c1 −V _full It becomes the size. Further, when the backup voltage V _c2 is higher than the output voltage V _c1 , the power supply control voltage V _g2 has a magnitude proportional to the difference voltage ΔV _c = V _c2 −V _{c1 therebetween} .

Therefore, in the case of V _c2 <V _c1 , when V _c1 > V _full , the conductance control voltage V _g becomes a voltage proportional to the difference voltage ΔV, and the difference voltage ΔV is transferred from the input / output node 16 b to the backup power storage device 22. A corresponding amount of current flows. On the other _hand, V _c2> in the case of _{V c1} is the conductance control voltage _{V g} becomes a voltage proportional to the difference voltage [Delta] V _c, the magnitude of the current corresponding from the backup power storage device 22 to a differential voltage [Delta] V _c to the output nodes 16b Leaks.

The overcharge prevention circuit 14 is a circuit that disconnects the charge input switch circuit 14a when the voltage (backup voltage V _c2 ) between both terminals of the backup power storage device 22 reaches the threshold voltage V _full . The overcharge prevention circuit 14 includes an operational amplifier 32. The operational amplifier 32 has two inputs, one of which receives the comparison voltage V _c2 ′ and the other of which receives the reference voltage V _ref output from the reference generation circuit 12. When the comparison voltage V _c2 ′ is higher than the reference voltage V _ref (that is, when V _c2 <V _full ), the operational amplifier 32 _generates a voltage V _g3 proportional to the difference voltage between the reference voltage V _ref and the comparison voltage V _c2 ′. Output.

The charge input switch circuit 14 a includes an n-channel MOS transistor 33, an n-channel MOS transistor 34, and a resistance element 35. The MOS transistor 34 is connected between the input / output nodes 16a and 16b. MOS transistor 33 is connected between the gate of MOS transistor 34 and ground node 17. The resistance element 35 is connected between the input / output node 16 a and the source of the MOS transistor 33. The voltage V _g3 output from the operational amplifier 32 is input to the gate of the MOS transistor 33.

When V _c2 <V _full , the backup power storage device 22 still has room for charging. In this case, V _g3 is 0. As a result, the MOS transistor 33 is turned off, and the gate of the MOS transistor 34 has the same potential as the output voltage of the rectifier circuit 10. Accordingly, the MOS transistor 34 is turned on, the input / output nodes 16a and 16b are connected, and a current can be input to the input / output node 16b.

On the other hand, when V _c2 ≧ V _full , the backup power storage device 22 is fully charged, and when a charging current is further input, the output voltage exceeds the threshold voltage V _full . In this case, since V _g3 increases according to the value of V _c2 −V _full , the MOS transistor 33 is turned on, and the gate voltage of the MOS transistor 34 becomes the ground potential. Therefore, MOS transistor 34 is turned off, and input / output nodes 16a and 16b are disconnected. Thereby, the current input to the input / output node 16b is cut off, and overcharge is prevented.

The power supply control circuit 15 includes voltage dividing resistors 36 and 37 and a comparator 38 with hysteresis. The power supply switch circuit 15a is composed of a p-channel MOS transistor. Voltage dividing resistors 36 and 37 are connected in series between input / output node 16 b and ground node 17. Voltage dividing resistors 36 and 37, output node constant dividing ratio output voltage _{V c1} occurring 16b _{(R l1:} R _l2) in divide, cut in two comparative voltage _{V l} to the connection node of resistors 36 and 37 Is generated.

The comparator with hysteresis 38 has two inputs, one of which receives the comparison voltage V ₁ and the other of which outputs the reference voltage V _ref output from the reference generation circuit 12. The input / output characteristics of the comparator with hysteresis 38 are shown. 4A shows the peripheral circuit portion of the comparator with hysteresis 38 in FIG. 3, and FIG. 4B shows the input / output characteristics of the comparator 38 with hysteresis. Since the voltage V _l is proportional to the voltage V _c1 , the horizontal axis of FIG. 4B is indicated by the voltage V _c1 .

Hysteresis comparator with 38, in the case of the output voltage _{V g4} is _V H (H level), exceeds the voltage _{V full} voltage _{V c1} rises, the output voltage _{V g4} becomes 0 (L level). _Here, a _{V full = (V ref + Δ} ) (R l1 + R l2) / R l2.

This voltage V _g4 is input to the gate of the feed switch circuit 15a. By this state transition, the power supply switch circuit 15a is switched from the off state to the on state. Thus, immediately after the start of power storage, the power supply switch circuit 15a holds the power supply switch circuit 15a in an off state during a period in which the power is not sufficiently stored and the output voltage _Vc1 does not reach the voltage _Vfull. sufficiently, the output voltage _{V c1} is the power storage switches the power supply switch circuit 15a from reaching the voltage _{V full} oN state.

Conversely, when the output voltage V _g4 is 0 (L level) and the voltage V _c1 drops and falls below V _th2 , the output voltage V _g4 becomes V _H (H level). _Here, a _{V th2 = (V ref -Δ)} (R l1 + R l2) / R l2. With this state transition, the power supply switch circuit 15a is switched from the on state to the off state.

Here, the threshold voltage V _th2 is set to a value larger than the minimum value of the power supply voltage necessary for driving the load circuit 4. As a result, when the output voltage V _c1 drops to the power supply voltage necessary for driving the load circuit 4 and the stored power becomes insufficient, the power supply switch circuit 15a is turned off, and power is supplied to the load circuit 4. Is cut off.

FIG. 5 is a diagram illustrating an example of a circuit configuration of the reference generation circuit 12. Thus, a bandgap reference circuit can be used for the reference generation circuit 12. Note that the voltage V _c1 of the input / output node 16b is used as the power source of the reference generation circuit 12 in order to supply the power source in the wireless sensor.

  FIG. 6 is a diagram illustrating the circuit configuration (a) of each operational amplifier and the circuit configuration (b) of the wired NOR circuit 30 in FIGS. 3 and 5. These are the same as the normally used operational amplifier and wired NOR circuit, and detailed description thereof is omitted.

  In FIG. 6A, an n-channel MOS transistor is used for the differential input pair. However, the polarity of all the MOS transistors in FIG. An operational amplifier using a channel MOS transistor can also be used. Furthermore, if the output of the operational amplifier in FIG. 6A is positively fed back to the input side, the comparator 38 with hysteresis can be configured.

  The operation of the power control apparatus 3 according to this embodiment configured as described above will be described below. FIG. 7 is a diagram illustrating the voltage-current characteristics in the saturation region of the variable conductance element 23. 8 and 9 are diagrams showing the time change of the output voltage of the power control device 3. In FIGS. 8 and 9, the power generation sensor element 2 always outputs a constant current for the sake of simplicity.

  FIG. 8A shows the charging operation of the power control apparatus 3 when there is no power consumption by the load circuit 4.

It is assumed that no electric power is stored in the initial power storage device 21 and the backup power storage device 22 at time 0. When V _c1 = 0, the MOS transistor 34 is in a diode-connected state, and the conductance of the variable conductance element 23 is 0. Further, the power supply switch circuit 15a is also in an off state. In this state, the current supplied from rectifier circuit 10 flows into input / output node 16 b and is stored in initial power storage device 21. Along with this, the output voltage V _c1 starts to rise. Assuming that the current flowing into the initial power storage device 21 is I, V _c1 = I · t / C ₁ . Since the capacitance _{C 1} of the initial power storage device 21 is _{small, V c1} rises rapidly.

At time _{t 1,} the output voltage _{V c1} reaches the threshold voltage _{V full.} Then, the output voltage V _{g4 of the} comparator with hysteresis 38 becomes zero. Accordingly, the power supply switch circuit 15a is turned on, and V _out = V _c1 . Thereby, the load circuit 4 can use the power supply voltage.

Further, when the output voltage V _c1 reaches the threshold voltage V _full at time t ₁ , V _c1 ′ = V _ref is _satisfied . When the current is further supplied from the rectifier circuit 10 to the input / output node 16b, the current flows into the initial power storage device 21, and the output voltage _Vc1 further increases. Accordingly, the difference voltage ΔV = V _c1 ′ −V _ref becomes larger than 0. When the difference voltage ΔV becomes greater than 0, the storage control voltage V _g1 = A _op ΔV = A (V _c1 −V _full ) (A _op is the gain of the operational amplifier 26) is output in proportion thereto, which is the conductance control voltage V _g. Is input to the gate of the variable conductance element 23. At this time, the variable conductance element 23 is in the saturation region, and its voltage-current characteristics are as shown in FIG. Therefore, the conductance of the variable conductance element 23 suddenly increases from 0, and current starts to flow from the input / output node 16b to the backup power storage device 22. At this time, if the conductance becomes excessively large and the output voltage V _c1 of the input / output node 16b is to be lowered to the threshold voltage V _full or less, the conductance of the variable conductance element 23 returns to 0. _c1 does not fall below the threshold voltage _Vfull . In this way, the output voltage V _c1 is always kept in balance with the value of the threshold voltage V _full , and the current supplied to the input / output node 16 b flows into the backup power storage device 22 and is stored. Then, the voltage (backup voltage V _c2 ) of the backup power storage device 22 starts to rise.

Assuming that the current flowing into the backup power storage device 22 is I, V _c2 = I · t / C ₂ . Since the capacitance _{C 2} of the backup power storage device 22 is _{large, V c2} is gradually increased.

In time _{t 2, the} backup voltage _{V c2} reaches the threshold voltage _{V full.} Accordingly, the comparison voltage V _c2 ′ reaches the reference voltage V _ref . Then, the voltage V _g3 output from the operational amplifier 32 becomes 0, and the MOS transistors 33 and 34 are turned off. Accordingly, the input / output nodes 16a and 16b are disconnected, overcharge is prevented, and both the output voltage V _c1 and the backup voltage V _c2 are maintained at the threshold voltage V _full .

As described above, in the power control device 3 of this embodiment, after the output voltage V _c1 reaches the threshold voltage V _full , the current flowing through the backup power storage device 22 is continuously controlled by the variable conductance element 23, and V _The backup power storage device 22 is charged while maintaining an equilibrium state of _c1 = _Vfull . As a result, it is possible to obtain a stable power supply voltage without a sudden change in the output voltage V _c1 . Further, until the charging of the initial power storage device 21 is completed (V _c1 = V _full ), the backup power storage device 22 is not charged at all, and only the initial power storage device 21 is charged. Can be shortened (period [0, t ₁ ]) until the use of the power source is completed.

Next, a case where there is power consumption by the load circuit 4 will be described. FIG. 8B shows a change in output voltage when power is consumed in the load circuit 4 in a state where the backup voltage V _c2 of the backup power storage device 22 does not reach the threshold voltage V _full .

At time _{t 1,} the output voltage _{V c1} is after reaching the threshold voltage _{V full,} and at time _t 2 ~t ₃ power consumption by the load circuit 4 has been. At this time, when the power stored in the initial power storage device 21 is consumed, the output voltage V _c1 drops to a value lower than the threshold voltage V _full . However, in this case, V _g2 = 0 because V _c1 > V _c2 . Therefore, V _g = 0, and the conductance of the variable conductance element 23 is 0. For this reason, the power stored in the backup power storage device 22 is not consumed, and only the power stored in the initial power storage device 21 is consumed. Since the electrostatic capacity C ₁ of the initial power storage device 21 is small, the output voltage V _c1 drops relatively quickly with the power consumption of the load circuit 4.

However, after the power consumption of the load circuit 4 is completed at time t _3, real initial power storage device 21 is charged, the output voltage V _c1 at time t _4, together with the return again to the threshold voltage V _full, energy storage backup Charging to the device 22 is resumed.

FIG. 9 shows a change in the output voltage when power is consumed in the load circuit 4 in a state where the backup voltage V _c2 of the backup power storage device 22 reaches the threshold voltage V _full .

The output voltage V _c1 has already reached the threshold voltage V _full . At time _{t 1,} the backup after voltage _{V c2} has reached the threshold voltage _{V full,} and at time _t 2 ~t ₃ power consumption by the load circuit 4 has been. At this time, when the power stored in the initial power storage device 21 is consumed, the output voltage V _c1 drops to a value lower than the threshold voltage V _full . Then, since V _c1 ′ <V _c2 ′, the power supply control voltage V _g2 increases according to ΔV _c = V _c2 ′ −V _c1 ′. As a result, the conductance of the variable conductance element 23 also increases, and eventually the electric power stored in both the initial power storage device 21 and the backup power storage device 22 is consumed while maintaining an equilibrium state of V _c1 = V _c2 . At this time, since the electrostatic capacity of the backup power storage device 22 is large, the rate of decrease of the output voltage V _c1 due to the power consumption of the load circuit 4 becomes very slow.

When the power consumption of the load circuit 4 ends at time t _3, firstly, to recover the output voltage V _c1 initial power storage device 21 is charged immediately until the threshold voltage V _full, then the backup power storage device 22 is charged, The backup voltage V _c2 is restored to the threshold voltage V _full .

FIG. 10 is a diagram illustrating a detailed circuit configuration of the power control device 3 according to the second embodiment of the present invention. The power control device 3 according to the present embodiment is different from the first embodiment in that the initial power storage device 21 and the backup power storage device 22 are connected in series between the input / output node 16b and the ground node 17, In other respects, the configuration is substantially the same. Corresponding circuit components in FIGS. 3 and 10 are denoted by the same reference numerals. In FIG. 10, the output voltage of the input / output node 16 b is denoted as V _c12 , and the voltage across the initial power storage device 21 is denoted as V _c1 . Further, the _divided voltage of the output voltage V _c12 generated at the connection node of the voltage _dividing resistors 24 and 25 is denoted as V _c12 ′.

  In this embodiment, the variable conductance element 23 is connected between the input / output node 16 b and the backup power storage device 22 in parallel with the initial power storage device 21. The other points are the same as in FIG.

  FIGS. 11 and 12 are diagrams illustrating a time change of the output voltage of the power control device 3 according to the second embodiment.

  FIG. 11A shows the charging operation of the power control device 3 when there is no power consumption by the load circuit 4.

It is assumed that no electric power is stored in the initial power storage device 21 and the backup power storage device 22 at time 0. When V _c12 = 0, the MOS transistor 34 is in a diode-connected state, and the conductance of the variable conductance element 23 is 0. The power supply switch circuit 15a is in an off state. In this state, the current supplied from the rectifier circuit 10 flows into the input / output node 16b and is stored in the initial power storage device 21 and the backup power storage device 22 connected in series. _Along with this, the output voltage V _c12 starts to rise. Assuming that the current flowing into the initial power storage device 21 is I, V _c1 = I (C ₁ + C ₂ ) t / (C ₁ · C ₂ ). Since the electrostatic capacity C ₁ of the initial power storage device 21 is sufficiently smaller than C ₂ (for example, C ₁ ≧ 0.1 · C ₂ is set), V _c12 rises rapidly.

The voltages applied to the initial power storage device 21 and the backup power storage device 22 are V _c1 = I · t / C ₁ and V _c2 = I · t / C ₂ , respectively. Since the electrostatic capacity C ₁ of the initial power storage device 21 is set sufficiently smaller than the electrostatic capacity C ₂ of the backup power storage device 22, V ₁ > V ₂ is satisfied.

At time _{t 1,} the output voltage _{V c12} exceeds the threshold voltage _{V full.} Then, the output voltage V _{g4 of the} comparator with hysteresis 38 becomes zero. Therefore, the power supply switch circuit 15a is turned on, and V _out = V _c12 is obtained. Thereby, the load circuit 4 can use the power supply voltage.

Further, when the output voltage V _c12 reaches the threshold voltage V _full at time t ₁ , V _c12 ′ = V _ref is _satisfied . When the current is further supplied from the rectifier circuit 10 to the input / output node 16b, the output voltage _Vc12 further increases. Accordingly, the difference voltage ΔV = V _c12 ′ −V _ref becomes larger than 0. When the difference voltage ΔV becomes greater than 0, the storage control voltage V _g1 is output in proportion thereto, and this is input to the gate of the variable conductance element 23 as the conductance control voltage V _g . Then, the conductance of variable conductance element 23 becomes greater than 0, and current starts to flow from backup input / output node 16b to backup power storage device 22. At the same time, the electric charge of the initial power storage device 21 is discharged. In this way, the output voltage V _c12 is always in a balanced state with the value of the threshold voltage V _full , and the current supplied to the input / output node 16 b flows into the backup power storage device 22 and is stored, The electric charge of the electrical storage device 21 is discharged. Then, the voltage of the backup power storage device 22 (backup voltage V _c2 ) starts to increase, and the initial boosted voltage V _c1 starts to decrease. That is, the initial boosted voltage V _c1 of the initial power storage device 21 in the threshold voltage V _full is replaced with the backup voltage V _c2 .

Here, when the current flowing into the backup power storage device 22 is I, V _c2 = I · t / C ₂ . Since the capacitance _{C 2} of the backup power storage device 22 is _{large, V c2} is gradually increased.

In time _{t 2, the} backup voltage _{V c2} is the threshold voltage _{V full,} the initial boost voltage _{V c1} reaches zero. Accordingly, the comparison voltage V _c2 ′ reaches the reference voltage V _ref . As a result, the voltage V _g3 output from the operational amplifier 32 is increased, the MOS transistor 33 is turned on, and the MOS transistor 34 is turned off. Accordingly, the input / output nodes 16a and 16b are disconnected, overcharge is prevented, and both the output voltage _Vc12 and the backup voltage _Vc2 are maintained at the threshold voltage _Vfull .

As described above, in the power control device 3 of the present embodiment, after the output voltage V _c12 reaches the threshold voltage V _full , the current flowing through the backup power storage device 22 is continuously controlled by the variable conductance element 23, and V while maintaining the equilibrium of _c12 = _{V full} performing power storage to the backup electric storage device 22. Thereby, it is possible to obtain a stable power supply voltage without any sudden change of the output voltage _Vc12 . Until the output voltage V _c12 reaches the threshold voltage V _full , the initial power storage device 21 and the backup power storage device 22 are completely connected in series, and the capacitance is C = C ₁ C ₂ / (C ₁ + _{C 2)} in _and, the C ≒ _{C 1} if _C 1 << C _2. Therefore, since the output voltage increases according to I · t / C≈I · t / C ₁ , it is possible to shorten the time (period [0, t ₁ ]) until charging is completed and the power supply can be used. it can.

Next, a case where there is power consumption by the load circuit 4 will be described. FIG. 11B shows a change in the output voltage when power is consumed in the load circuit 4 in a state where the backup voltage V _c2 of the backup power storage device 22 does not reach the threshold voltage V _full .

At time _{t 1,} the output voltage _{V c12} is after reaching the threshold voltage _{V full,} and at time _t 2 ~t ₃ power consumption by the load circuit 4 has been. At this time, when the electric power stored in the initial power storage device 21 and the backup power storage device 22 is consumed, the output voltage V _c12 drops to a value lower than the threshold voltage V _full . At this _time, since the partial pressure ratio of _{V c1} occupying the _{V full} large, the influence of the discharge of the capacitance small initial power storage device 21 appears larger at the output voltage _{V c12,} with the power consumption of the load circuit 4 output voltage _{V c12} Decreases relatively quickly.

However, after the power consumption of the load circuit 4 is completed at time t _3, real initial power storage device 21 is charged, the output voltage V _c1 at time t _4, together with the return again to the threshold voltage V _full, variable conductance element The charging of the backup power storage device 22 through 23 and the discharging of the initial power storage device 21 are resumed.

FIG. 12 shows changes in the output voltage when power is consumed in the load circuit 4 in a state where the backup voltage V _c2 of the backup power storage device 22 has reached the threshold voltage V _full .

The output voltage V _c12 has already reached the threshold voltage V _full . At time _{t 1,} the backup voltage _{V c2} reaches the threshold voltage _{V full,} the initial boost voltage _{V c1} is after reaching zero, and at time _t 2 ~t ₃ power consumption by the load circuit 4 has been. At this time, when the power stored in the backup power storage device 22 is consumed, the output voltage V _c12 drops to a value lower than the threshold voltage V _full . Then, since V _c12 ′ <V _c2 ′, the power supply control voltage V _g2 increases according to ΔV _c = V _c2 ′ −V _c12 ′. As a result, the conductance of the variable conductance element 23 also increases, and eventually the power stored in the backup power storage device 22 is consumed while maintaining the equilibrium state of V _c12 = V _c2 . At this time, since the electrostatic capacity of the backup power storage device 22 is large, the drop speed of the output voltage _Vc12 due to the power consumption of the load circuit 4 becomes very gradual.

When the power consumption of the load circuit 4 ends at time t ₃ , the initial power storage device 21 is immediately charged and the output voltage V _c12 is restored to the threshold voltage V _full , and then the backup power storage device 22 is charged. At the same time, the initial power storage device 21 is discharged, and the backup voltage V _c2 is restored to the threshold voltage V _full .

It is a figure explaining the structural example which connects the some backup electrical storage apparatus in this invention. It is a block diagram showing the structure of the wireless sensor and power control apparatus which concern on Example 1 of this invention. It is a figure which shows the detailed circuit structure of the power control apparatus 3 which concerns on Example 1. FIG. It is a figure showing the input-output characteristic of comparator 38 with hysteresis. 2 is a diagram illustrating an example of a circuit configuration of a reference generation circuit 12. FIG. 6 is a diagram illustrating a circuit configuration (a) of each operational amplifier in FIG. 3 and FIG. 5 and a circuit configuration (b) of a wired NOR circuit 30. FIG. 4 is a diagram illustrating voltage-current characteristics in a saturation region of a variable conductance element 23. FIG. It is a figure showing the time change of the output voltage of the electric power control apparatus 3 which concerns on Example 1. FIG. It is a figure showing the time change of the output voltage of the electric power control apparatus 3 which concerns on Example 1. FIG. It is a figure which shows the detailed circuit structure of the power control apparatus 3 which concerns on Example 2 of this invention. It is a figure showing the time change of the output voltage of the electric power control apparatus 3 which concerns on Example 2. FIG. It is a figure showing the time change of the output voltage of the electric power control apparatus 3 which concerns on Example 2. FIG. It is a figure showing the structure of the electric power control apparatus of patent document 6. FIG. 14 is a timing chart of the power control apparatus 102 illustrated in FIG. 13.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless sensor 2 Electric power generation type sensor element 3 Power control apparatus 4 Load circuit 4a Sensor circuit 4b Transmission / reception circuit 5 Antenna 10 Rectification circuit 11 Power storage circuit 12 Reference generation circuit 13 Power storage control circuit 14 Overcharge prevention circuit 14a Charge input switch circuit 15 Power feeding Control circuit 15a Feed switch circuit 16a, 16b, 16c Input / output node 17 Ground node 20 Diode bridge circuit 21 Initial power storage device 22 Backup power storage device 23 Variable conductance element 24, 25, 27, 28, 36, 37 Voltage dividing resistor 26 , 29, 32 Operational amplifier 30 Wired NOR circuit 31 Backup output node 33, 34 MOS transistor 35 Resistance element 38 Comparator with hysteresis

Claims (5)

A power control device that stores direct current or pulsating current input to an input / output node and outputs a voltage to the input / output node,
An initial power storage device that is connected to the input / output node and stores a current input to the input / output node;
Variable conductance element with variable conductance;
One or more backup power storage devices that are connected to the input / output node via the variable conductance element and store a current input to the input / output node;
In addition, when the voltage of the input / output node (hereinafter referred to as “output voltage”) exceeds a certain threshold voltage, the variable conductance according to a conductance change characteristic that monotonously increases with respect to a difference voltage between the output voltage and the threshold voltage. A storage control circuit for controlling the conductance of the element;
A power control apparatus comprising: The power control apparatus according to claim 1, wherein the initial power storage device is connected to the input / output node in parallel with the backup power storage device and the variable conductance element. The backup power storage device has a larger capacitance than the initial power storage device,
The power control apparatus according to claim 1, wherein the initial power storage device is connected in parallel with the variable conductance element and in series with the backup power storage device. A reference generation circuit that generates a constant reference voltage
When the voltage obtained by dividing the output voltage at a certain voltage division ratio (hereinafter referred to as “comparison voltage”) exceeds the reference voltage, the power storage control circuit has a difference voltage between the comparison voltage and the reference voltage. Is composed of an operational amplifier circuit that outputs a voltage proportional to (hereinafter referred to as “storage control voltage”),
4. The power control device according to claim 1, wherein the variable conductance element includes a field effect transistor whose conductance increases with an increase in the storage control voltage input to a gate terminal. 5. . A charge input switch circuit for intermittently supplying a current input to the input / output node;
And an overcurrent prevention circuit that disconnects the charge input switch circuit when a voltage between both terminals of the backup power storage device reaches the threshold voltage;
The power control apparatus according to any one of claims 1 to 4, further comprising:

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