JP2017216799A - Power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device while attaining downsizing and reduction in the number of components, the power supply device being capable of satisfactorily operating a voltage conversion part including a switching element and having a step-up function even in a case where a power supply voltage supplied from a power source part is low.SOLUTION: A power supply device 30 comprises: a voltage conversion part 40 capable of performing a step-up operation; a control part 60 which outputs a control signal for controlling operation of a switching element of the voltage conversion part 40; a drive part 54 to which an operation voltage is supplied on the basis of an output voltage that is outputted by the step-up operation in the voltage conversion part 40, and which outputs a drive signal corresponding to the control signal outputted from the control part 60 to the switching element in a case where the output voltage is equal to or higher than a predetermined threshold value; and an amplification part 56 which amplifies the control signal outputted from the control part 60 and outputs the amplified control signal to the switching element in a case where the output voltage is lower than the predetermined threshold value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power supply device.

  Japanese Patent Application Laid-Open No. 2004-133867 discloses a technique for boosting a voltage output from an auxiliary power supply by a booster circuit and supplying the voltage to a motor as a load when a battery failure occurs. The device disclosed in Patent Document 1 performs a boosting operation for generating a charging voltage for charging an auxiliary power supply using a battery voltage as an input by switching of a MOSFET, and the MOSFET is driven by a gate drive circuit.

Japanese Patent No. 5272406

  By the way, when the switching element provided in the power supply device is driven by the driving circuit, it is necessary to supply a certain level of operating voltage to the driving circuit. However, when a battery failure or the like occurs and the auxiliary power supply is used as a power supply source, a situation is assumed in which the output voltage from the auxiliary power supply does not reach a level at which the drive circuit can be operated. As a countermeasure against this problem, the device of Patent Document 1 includes a second booster circuit that generates a control power supply voltage, apart from a booster circuit that generates a charge voltage for charging an auxiliary power supply. When a battery failure occurs, the control power supply voltage boosted by the second booster circuit is supplied to each gate drive circuit.

  However, the device of Patent Document 1 is different from the first booster circuit that performs the boosting operation when the battery is in a normal state, and the second booster that boosts the applied voltage of the auxiliary power supply to generate the control power supply voltage. Since a circuit is provided, it is disadvantageous in terms of miniaturization. In particular, the booster circuit used in the device of Patent Document 1 requires an electronic component such as a coil having a certain amount of inductance, and this device requires a plurality of such booster circuits. There is a problem that the size and the number of parts are likely to increase.

  The present invention has been made based on the above circumstances, and even when the power supply voltage supplied from the power supply section is low, the voltage conversion section having a switching element and having a boosting function can be operated satisfactorily. An object of the present invention is to realize a power supply device that can be reduced in size and reduced in the number of components.

The power supply device of the present invention is
A voltage converter that boosts and outputs an input voltage by turning on and off the switching element; and
A control unit that outputs a control signal for controlling the operation of the switching element;
When an operating voltage is supplied based on the output voltage output by the voltage boosting operation in the voltage conversion unit and the output voltage is equal to or higher than a predetermined threshold, a drive signal corresponding to the control signal output from the control unit A drive unit that outputs to the switching element;
An amplifier for amplifying the control signal output from the control unit and outputting the amplified control signal to the switching element when the output voltage is less than a predetermined threshold;
Is provided.

  Since the power supply device of the present invention can supply the operating voltage to the drive unit using the voltage boosted by the voltage conversion unit, even when the power supply voltage supplied from the power supply unit is low, A high operating voltage can be supplied to the drive unit by using the boosting operation of the voltage conversion unit. In addition, since the operating voltage of the driving unit that drives the voltage converter can be generated using the boosting operation of the driven voltage converting unit, a dedicated booster circuit for generating the operating voltage of the driving unit is provided. It is not necessary to provide a separate device, which makes it easier to reduce the size and the number of parts.

  However, in the configuration in which the operation voltage of the drive unit that drives the voltage conversion unit is generated based on the output of the driven voltage conversion unit, the drive unit is not operating the voltage conversion unit (that is, for controlling the drive unit). The problem is that the operating voltage cannot be supplied to the drive section when the corresponding boosting operation is not performed. In other words, if the voltage conversion unit cannot be operated in a situation where the drive unit is not operating, “the operation voltage of the drive unit is generated using the boost operation of the voltage conversion unit driven by the drive unit”. It is not possible to shift to the operation. The present invention also solves this problem, and the control signal output from the control unit can be amplified by the amplifying unit and output to the switching element. That is, since the switching element can be operated by the amplifying unit even when the driving unit is not operating, the above problem is solved.

  Therefore, even when the power supply voltage supplied from the power supply unit is low, a power supply device that can operate a voltage conversion unit having a switching element and a boosting function can be reduced in size and the number of components can be reduced. It can be realized while planning.

1 is a circuit diagram schematically illustrating an in-vehicle system including a power supply device according to a first embodiment. FIG. 3 is a circuit diagram illustrating details of an amplifying unit in the power supply device according to the first embodiment.

Here, a desirable example of the present invention will be shown.
In the power supply device of the present invention, the first power supply unit and the load are electrically connected and the first conductive path to which the output voltage from the voltage conversion unit is applied, and the second power supply unit is electrically connected and the voltage conversion is performed. A second conductive path to which an input voltage to the unit is applied.

  The power supply device configured as described above, for example, from the second power supply unit to the load electrically connected to the first power supply unit when power cannot be normally supplied from the first power supply unit to the load. Can be supplied after voltage conversion. That is, the second power supply unit can be used as a backup power supply. In addition, when the second power supply unit is used as a backup power supply, it is possible to boost the input voltage from the second power supply unit side and generate an operating voltage to be given to the drive unit, so that the first power supply unit fails, The drive unit can be operated even when the output voltage of the second power supply unit is low.

  The amplifying unit may be configured to amplify the control signal using the power supply voltage output from the second power supply unit as the operating voltage.

  The power supply device configured as described above can supply the power supply voltage of the second power supply unit even at the time before the control of the voltage conversion unit by the drive unit is started (that is, the time when the drive unit is not operating). The control signal output from the control unit can be amplified by using it, and appropriate on-voltage and off-voltage can be applied to the switching element of the voltage conversion unit.

  The voltage conversion unit is configured as a switching element and is electrically connected to the first conductive path, and the second MOSFET is configured as a switching element and is electrically connected to the first MOSFET. And a coil portion having one end electrically connected between the first MOSFET and the second MOSFET and the other end electrically connected to the second conductive path. The coil portion side of the first MOSFET It is possible to adopt a configuration in which a diode that allows energization to the first conductive path side is disposed. The drive unit outputs a first signal to the first MOSFET and outputs a second signal to the second MOSFET based on a control signal from the control unit, and a first control to turn off the first MOSFET. The second control for outputting a signal and outputting an ON signal to the second MOSFET can be performed by switching. The amplifying unit can output an amplified signal obtained by amplifying the control signal to the second MOSFET.

  According to this configuration, when the driving unit cannot be driven, the switching operation of the second MOSFET can be performed by the amplifying unit and the diode-type boosting operation can be performed using the diode of the first MOSFET that has been turned off. In addition, when the boost operation of the voltage conversion unit progresses and the drive unit can be driven, both the first MOSFET and the second MOSFET can be turned on / off by the drive unit, so that the loss is reduced by the synchronous rectification method. The boosting operation can be performed in a form that suppresses this.

  The power supply device of the present invention inputs a control signal from the control unit to the drive unit when the output voltage from the voltage conversion unit is greater than or equal to a predetermined threshold value, and outputs a control signal when the output voltage is less than the predetermined threshold value. A switching unit for inputting to the amplifying unit may be provided.

  In the power supply device configured in this way, when the output from the voltage conversion unit is relatively low and the driving unit is unlikely to operate normally, the control signal from the control unit is input to the amplification unit, The voltage converter can be operated by the amplified signal from the amplifier. In addition, when the output from the voltage conversion unit becomes relatively high and the possibility that the drive unit operates normally increases, a control signal from the control unit is input to the drive unit, and the voltage conversion unit is driven by the drive unit. Can be driven.

<Example 1>
Embodiment 1 of the present invention will be described below.
(Configuration of power supply)
First, the power supply device 30 and related configurations will be described.
The in-vehicle system 10 shown in FIG. 1 is configured as an in-vehicle power supply system, and includes a first power supply unit 91, a second power supply unit 92, a fuse unit 93, a load 94, a power supply device 30, and the like. The in-vehicle system 10 has a configuration capable of supplying power from the first power supply unit 91 to the load 94, and further has a configuration capable of supplying power also from the first power supply unit 91 to the second power supply unit 92. . That is, the first power supply unit 91 is configured to be able to supply both the load current and the charging current. Further, the in-vehicle system 10 is configured to be able to supply electric power from the second power supply unit 92 to the load 94 at a predetermined time (for example, when the first power supply unit 91 fails).

  The first power supply unit 91 is a DC power source that generates a DC voltage, and a known power storage means such as a lead battery is used. The first power supply unit 91 is provided with a high potential side terminal and a low potential side terminal. The high potential side terminal is electrically connected to the first conductive path 31, and the low potential side terminal is electrically connected to, for example, ground. Connected. The 1st power supply part 91 comprises the structure which applies a predetermined | prescribed output voltage with respect to the 1st conductive path 31, for example, the output voltage at the time of a full charge is about 12V-14V. Note that a generator (not shown) is electrically connected to the first conductive path 31, and the first power supply unit 91 can be charged by the generated power from the generator.

  The fuse portion 93 is configured as a well-known in-vehicle fuse component, and is provided in a wiring 81 that is a conductive path electrically connected to the first power supply portion 91. One end of the fuse portion 93 is electrically connected to the first power source portion 91 via the wiring 81, and the other end is electrically connected to the first switch portion 34 via the first conductive path 31. The fuse part 93 forms a part of a path (energization path) between the first power supply part 91 and the first switch part 34 when not blown, and a current exceeding a predetermined current value (a fusing current value of the fuse part 93) is itself. When the current flows, the fuse between the first power supply 91 and the first switch 34 is made non-energized.

  The load 94 is a known in-vehicle electric component, and for example, various electric components such as a navigation system, an audio, an air conditioner, a meter, and a transmission are applicable. The load 94 is electrically connected to the wiring 83 and is electrically connected to the first conductive path 31 via the wiring 83.

  The second power supply unit 92 is a DC power supply that outputs a DC voltage, and includes, for example, an electric double layer capacitor. One terminal (high potential side terminal) of the second power supply unit 92 is electrically connected to the second conductive path 32 via the wiring 82, and a predetermined output voltage is applied to the other terminal (low potential side). Terminal) is electrically connected to ground. The second power supply unit 92 is charged by, for example, supplying a charging current by a step-down operation by the voltage conversion unit 40.

  The second power supply unit 92 can function as a backup power supply for the first power supply unit 91. For example, even when the first switch unit 34 is in an off state and no power is supplied from the first power supply unit 91 to the load 94, the voltage conversion unit 40 performs the boosting operation to perform the second power supply unit 92. Can be supplied to the load 94, and a desired voltage can be applied to the load 94. Note that the second power supply unit 92 has a smaller output voltage when fully charged than an output voltage when the first power supply unit 91 is fully charged.

  The power supply device 30 includes a first conductive path 31, a second conductive path 32, a first switch unit 34, a current detection unit 36, a voltage detection unit 37, a drive circuit unit 38, a control unit 39, a voltage conversion unit 40, and the like. ing.

  The first switch unit 34 is provided between the connection unit 33 and the first power supply unit 91 in the first conductive path 31 (specifically, between the connection unit 33 and the fuse unit 93). And the connection portion 33 have a function of switching between a non-energized state in which bidirectional energization is interrupted and an energized state in which a current can flow.

  The first conductive path 31 is a conductive path serving as a power path between the first power supply unit 91 and the load 94, and is electrically connected to each of the first power supply unit 91 and the load 94. The connection portion 33 is a portion in the first conductive path 31 where the first path 31A and the second path 31B are connected. The first path 31 </ b> A is a conductive path serving as a current path when a current flows from the first power supply unit 91 to the load 94. The second path 31 </ b> B is a conductive path branched from the first path 31 </ b> A and connected to the voltage conversion unit 40. The first conductive path 31 is configured to apply an input voltage to the voltage conversion unit 40 in a step-down mode described later.

  The second conductive path 32 is electrically connected to the second power supply unit 92 via the semiconductor switch element 48. The second conductive path 32 is configured such that an input voltage to the voltage conversion unit 40 is applied in a boost mode described later.

  The first switch unit 34 includes two semiconductor switch elements, and specifically includes a first switch element 34A and a second switch element 34B. The first switch element 34A and the second switch element 34B are both configured as MOSFETs and are disposed in opposite directions. Specifically, the source of the first switch element 34A is electrically connected to the first power supply part 91 via the fuse part 93 and the first conductive path 31, and the drain is connected to the drain of the second switch element 34B. Yes. The source of the second switch element 34B is electrically connected to the load 94 via the second conductive path 32, and the drain is connected to the drain of the first switch element 34A. In the first switch section 34, the parasitic diode 34C of the first switch element 34A and the parasitic diode 34D of the second switch element 34B are opposite to each other, and the parasitic diode 34C is connected to the first power supply section 91 side from the connection section 33 side. The parasitic diode 34D is arranged in a configuration that does not flow current from the first power supply unit 91 side to the connection unit 33 side. Therefore, when the first switch element 34A and the second switch element 34B are in the OFF state, no current flows through the parasitic diodes 34C and 34D, and bidirectional energization can be cut off.

  The voltage conversion unit 40 is configured as a known DCDC converter, and can perform a step-down operation and a step-up operation when the switching element is turned on and off. The voltage conversion unit 40 steps down the voltage input from the first conductive path 31 and outputs the voltage to the second conductive path 32, and boosts the voltage input from the second conductive path 32 to increase the first conductive path 32. 31.

  The voltage conversion unit 40 is configured as a switching element and electrically connected to the first conductive path 31, and is configured as a switching element and electrically connected to the semiconductor switch element 42. The semiconductor switch element 44 (second MOSFET) connected to each other and one end between the semiconductor switch element 42 and the semiconductor switch element 44 are electrically connected and the other end is electrically connected to the second conductive path 32. Coil portion 46. The semiconductor switch element 42 is configured as an N-channel type MOSFET, the drain is electrically connected to the first conductive path 31, and the source is connected to one end of the coil part 46 and the drain of the semiconductor switch element 44. In the semiconductor switch element 42, a parasitic diode 42A that allows energization from the coil portion 46 side to the first conductive path 31 side is disposed. The semiconductor switch element 44 is configured as an N-channel MOSFET, the drain is electrically connected to the source of the semiconductor switch element 42 and one end of the coil section 46, and the source is connected to the ground.

  The semiconductor switch element 48 is provided in the second conductive path 32, and the semiconductor switch element 48 can cut off the current from the second power supply unit 92 side to the first conductive path 31 side during the off operation. . In this configuration, the semiconductor switch element 48 and the semiconductor switch element 42 function as the second switch unit 35, and bidirectional energization can be interrupted when the second switch unit 35 is turned off.

  The drive circuit unit 38 includes a stabilization circuit 52, a drive unit 54, an amplification unit 56, and a changeover switch 58.

  The stabilization circuit 52 is configured as a known stabilization circuit. The stabilization circuit 52 has a configuration in which a voltage applied to the first conductive path 31 is used as an input voltage, and a stabilized output voltage is generated and applied to the drive unit 54.

  The drive unit 54 is configured as a known gate drive IC, and can drive the semiconductor switch elements 42 and 44 in accordance with a control signal from the control unit 39. The drive unit 54 uses the voltage generated by the stabilization circuit 52 as an operating voltage, operates when the voltage applied from the stabilization circuit 52 is equal to or higher than a predetermined value, and the voltage applied from the stabilization circuit 52 is When it is less than the predetermined value, the operation is stopped. The drive unit 54 supplies a drive signal corresponding to a control signal supplied from the control unit 39 via the signal line 51A to the gate of the semiconductor switch element 42 via the signal line 59A and an input line 57A. A drive operation can be performed in which a drive signal corresponding to the control signal is supplied to the gate of the semiconductor switch element 44 via the signal line 59B.

  The changeover switch 58 is a switch controlled by the control unit 39, and a path for conducting the signal line 51 </ b> B connected to the control unit 39 is connected to the input line 57 </ b> A connected to the drive unit 54 or the amplification unit 56. It operates to switch to one of the input lines 57B. In this configuration, the control unit 39 and the changeover switch 58 correspond to an example of a switching unit, and when the output voltage from the voltage conversion unit 40 is equal to or higher than a predetermined threshold, a control signal from the control unit 39 (specifically, A control signal for controlling the low-side semiconductor switch element 44) is input to the drive unit 54, and when the output voltage from the voltage conversion unit 40 is less than a predetermined threshold, the control signal is input to the amplification unit 56. To work.

  The amplification unit 56 has a function of amplifying the control signal output from the control unit 39 and outputting the amplified control signal to the semiconductor switch element 44 (switching element). The amplifying unit 56 operates using the power supply voltage output from the second power supply unit 92 as an operating voltage, and an amplified signal obtained by amplifying the control signal supplied from the control unit 39 is supplied to the semiconductor switch element 44 (second MOSFET). Can be output.

  Specifically, the amplifying unit 56 can be configured as shown in FIG. The amplifying unit 56 shown in FIG. 2 is an amplifying circuit composed of two transistors 56A and 56B. Specifically, the output voltage from the second power supply unit 92 is applied to the collector of the NPN transistor 56A, and the collector of the PNP transistor 56B is connected to the ground. The bases of the transistors 56B are both electrically connected to the input line 57B, and the emitters of the transistors 56A and 56B are both electrically connected to the signal line 59B.

  The amplifier 56 operates to amplify the voltage input to the input line 57B and output the amplified voltage to the signal line 59B. The signal line 59 </ b> B is an electric circuit connected to the gate of the semiconductor switch element 44, and when the amplifying unit 56 operates, the amplified signal from the amplifying unit 56 is input to the gate of the semiconductor switch element 44. Specifically, when the changeover switch 58 is switched so that the signal line 51B from the control unit 39 and the input line 57B are conductive, the control signal from the control unit 39 (for controlling the semiconductor switch element 44). Control signal) is input to the amplifying unit 56, and the amplifying unit 56 operates to amplify the control signal and output it to the signal line 59B. When the changeover switch 58 is switched so that the signal line 51B and the input line 57A are conductive, a control signal (control signal for controlling the semiconductor switch element 44) from the control unit 39 is sent to the drive unit 54. The drive signal that is input and generated by the drive unit 54 is output to the signal line 59B.

  The amplifying unit 56 is configured to operate even at a voltage lower than the voltage (the above-described predetermined value) that allows the driving unit 54 to be driven. Further, the voltage applied to the collector of the transistor 56A when the second power supply unit 92 is fully charged is higher than the voltage (for example, 5V) at which the control unit 39 can operate, and is applied to the signal line 51B. The voltage is higher than the high level signal of the control signal. The control unit 39 is supplied with an operating voltage based on the power from the first power supply unit 91 or the second power supply unit 92. When the first power supply unit 91 has failed, the control unit 39 receives power from the second power supply unit 92. The operating voltage is supplied based on the above.

  The current detection unit 36 is provided at a predetermined position of the first conductive path 31 (specifically, a position between the connection unit 33 and the load 94). The current detection unit 36 is configured as a known current detection circuit, and is a value that can specify the current value Iout of the current flowing through the first conductive path 31 (specifically, corresponds to the magnitude of the current flowing through the first conductive path 31). Output voltage value). For example, the current detection unit 36 includes a resistor and a differential amplifier that are interposed in the first conductive path 31. A voltage across the resistor is input to the differential amplifier, and a resistance is generated by a current flowing through the first conductive path 31. The voltage drop generated in the amplifier is amplified by a differential amplifier and output as a detection value. The detection value (current value Iout) output from the current detection unit 36 is input to the control unit 39.

  The voltage detector 37 is a predetermined position in the first conductive path 31 (specifically, a value that can specify the voltage value Vout of the second path 31B (specifically, a voltage corresponding to the magnitude of the voltage at this position). For example, the voltage detection unit 37 specifies the voltage value Vout at the position A itself, or a value obtained by dividing the voltage value Vout by a voltage dividing circuit. Output).

  The control unit 39 is configured as a control circuit including a microcomputer, for example, and includes a CPU, a storage unit, and the like. The control unit 39 functions to output a control signal that controls the operation of the switching element.

Next, the operation of the power supply device 30 will be described.
(Normal operation)
First, the operation in the normal state will be described. The power supply device 30 uses the first power supply unit 91 as a main power supply during normal operation. When the ignition switch is in the on state, in a normal state in which a predetermined abnormality described later does not occur, the first switch unit 34 is turned on, the voltage conversion unit 40 is turned off, and the semiconductor switch element 48 is operated. To turn off. With such an operation, power can be supplied from the first power supply unit 91 to the load 94.

  However, even in the normal state, when a predetermined charging condition is satisfied (for example, when the output voltage of the second power supply unit 92 is equal to or lower than a predetermined charging determination threshold value, this corresponds to a predetermined charging time) In this case, the voltage conversion unit 40 can be operated in the step-down mode, and the second power supply unit 92 can be charged by the power of the first power supply unit 91. When the voltage conversion unit 40 is operated in the step-down mode, the control unit 39 operates the changeover switch 58 so that the signal line 51B and the input line 57A are electrically connected. In this state, the gates of the semiconductor switch elements 42 and 44 are operated. A control signal (PWM signal) is output complementarily in a form in which a dead time is set. The drive unit 54 operates in response to such a control signal (PWM signal), and outputs an off signal to the semiconductor switch element 44 during output of the on signal to the semiconductor switch element 42, and outputs to the semiconductor switch element 42. During the output of the off signal, the semiconductor switch elements 42 and 44 are driven so as to output the on signal to the semiconductor switch element 44. The first state where the semiconductor switch element 42 is turned on and the semiconductor switch element 44 is turned off and the second state where the semiconductor switch element 42 is turned off and the semiconductor switch element 44 is turned on are alternately switched. Then, the DC voltage applied to the first conductive path 31 is stepped down and output to the second conductive path 32. The output voltage of the second conductive path 32 is determined according to the duty of the PWM signal applied to the gates of the semiconductor switch elements 42 and 44. In the step-down mode, the first conductive path 31 is an input-side conductive path, and the second conductive path 32 is an output-side conductive path.

  In the step-down mode, feedback control in a known manner is performed by the control unit 39, and based on a preset target voltage value and a detection value (voltage value at position B shown in FIG. 1) obtained by a voltage detection unit (not shown), The duty of the PWM signal given to the voltage conversion unit 40 is set so that the output voltage value of the voltage conversion unit 40 approaches the target voltage value. The control unit 39 continuously performs such feedback control while operating the voltage conversion unit 40 in the step-down mode. Although not shown, the power supply device 30 includes, for example, a voltage detection circuit that detects the voltage at the position B in the second conductive path 32, and the control unit 39 specifies the voltage value at the position B. It is a possible configuration. When the voltage conversion unit 40 is operated to charge the second power supply unit 92 in this way, for example, when the output voltage value of the voltage conversion unit 40 (voltage value at position B) reaches a certain value, the voltage conversion is performed. The operation of the unit 40 may be stopped and the semiconductor switch element 48 may be turned off. At this time, the current supply from the first conductive path 31 side to the second power supply unit 92 side and the current supply from the second power supply unit 92 side to the first conductive path 31 side are cut off.

(Operation in abnormal state)
In the power supply device 30 shown in FIG. 1, the control unit 39 monitors whether or not a predetermined abnormal state that should stop the power supply from the first power supply unit 91 has occurred. Specifically, by a voltage detection circuit (not shown), a predetermined position closer to the first power supply unit 91 than the first switch unit 34 (specifically, between the fuse unit 93 and the first switch unit 34 in the first conductive path 31). The control unit 39 continuously determines whether or not the voltage value at the position A is equal to or lower than a predetermined abnormality threshold due to occurrence of a short circuit or the like. When the voltage value at the position C becomes equal to or less than the predetermined abnormality threshold, the control unit 39 turns off the first switch unit 34 and puts the first switch unit 34 in a non-energized state. At this time, power supply from the first power supply unit 91 to the load 94 is cut off.

  When the power supply from the first power supply unit 91 side is interrupted in this way, the control unit 39 operates the voltage conversion unit 40 in the boost mode. When operating the voltage conversion unit 40 in the boost mode, the control unit 39 continuously monitors the detection value by the voltage detection unit 37, and whether the voltage value at the A position of the first conductive path 31 is equal to or greater than a predetermined threshold value. Continue to determine whether or not. The predetermined threshold is a value larger than the lower limit voltage value (the predetermined value described above) at which the drive unit 54 can operate.

  When the voltage value at the position A of the first conductive path 31 is less than a predetermined threshold value, a voltage necessary for driving cannot be applied to the drive unit 54. In this case, the control unit 39 operates the changeover switch 58 so as to connect the signal line 51B and the input line 57B, and outputs a control signal (PWM signal) for the gate of the semiconductor switch element 44 in this state. The amplifying unit 56 operates in response to such a control signal (PWM signal for the gate of the semiconductor switch element 44), amplifies the control signal from the control unit 39, and outputs the amplified signal to the gate of the semiconductor switch element 44. At this time, the semiconductor switch element 48 is maintained in the ON state by the control unit 39, and in the voltage conversion unit 40, the parasitic diode 42A, the semiconductor switch element 44, and the coil unit 46 operate as a diode type boost converter. In this case, when the semiconductor switch element 44 is alternately switched between the on state and the off state, the second conductive path 32 is used as the input side conductive path, and the first conductive path 31 is used as the output side conductive path. The DC voltage applied to the path 32 is boosted and output to the first conductive path 31. The output voltage of the first conductive path 31 is determined according to the duty of the PWM signal applied to the gate of the semiconductor switch element 44.

  Even in such a step-up mode, the control unit 39 performs feedback control in a known manner, and based on the preset target voltage value and the detection value obtained by the voltage detection unit 37, the output voltage value of the voltage conversion unit 40 ( The duty of the PWM signal applied to the voltage converter 40 is set so that the voltage value applied to the first conductive path 31 is close to the target voltage value. The control unit 39 continuously performs such feedback control while operating the voltage conversion unit 40 in the boost mode. Note that the target voltage value in the boost mode is a value larger than the lower limit voltage value (the above-mentioned predetermined value) at which the drive unit 54 can operate, and is a value larger than the above-described predetermined threshold value.

  When the operation in such a boosting mode proceeds, a boosted voltage is applied to the first conductive path 31, so that the voltage value at the A position of the first conductive path 31 becomes equal to or greater than a predetermined threshold value. As described above, when the voltage value at the position A of the first conductive path 31 is equal to or greater than a predetermined threshold, the voltage input to the drive unit 54 via the stabilization circuit 52 enables the drive unit 54 to operate. Since it becomes larger than the lower limit voltage value (the above-mentioned predetermined value), the drive unit 54 becomes operable. When the voltage value at the position A of the first conductive path 31 is equal to or greater than a predetermined threshold, the control unit 39 causes the voltage conversion unit 40 to operate as a synchronous rectification type DCDC converter. Specifically, the changeover switch 58 is operated so as to make the signal line 51B and the input line 57A conductive, and in this state, the dead time is set for the control signal (PWM signal) for each gate of the semiconductor switch elements 42 and 44. Output complementarily. The drive unit 54 operates in response to such a control signal (PWM signal), and outputs an off signal to the semiconductor switch element 44 during output of the on signal to the semiconductor switch element 42, and outputs to the semiconductor switch element 42. During the output of the off signal, the semiconductor switch elements 42 and 44 are driven so as to output the on signal to the semiconductor switch element 44. The first state where the semiconductor switch element 42 is turned on and the semiconductor switch element 44 is turned off and the second state where the semiconductor switch element 42 is turned off and the semiconductor switch element 44 is turned on are alternately switched. Then, the DC voltage applied to the second conductive path 32 is boosted and output to the first conductive path 31. The output voltage of the first conductive path 31 is determined according to the duty of the PWM signal applied to the gates of the semiconductor switch elements 42 and 44. Thus, after the drive unit 54 becomes operable and the voltage conversion unit 40 performs the boosting operation according to the drive signal from the drive unit 54, the drive unit 54 is based on the output voltage of the voltage conversion unit 40. A sufficient operating voltage can be applied, and such an operating voltage can be continued.

  As described above, since the power supply device 30 can supply the operating voltage to the drive unit 54 using the voltage boosted by the voltage conversion unit 40, it is supplied from the second power supply unit 92 (power supply unit). Even when the power supply voltage is low, a high operating voltage can be supplied to the driving unit 54 by using the boosting operation of the voltage converting unit 40. In addition, since the operating voltage of the driving unit 54 that drives the voltage converting unit 40 can be generated by using the boosting operation of the driven voltage converting unit 40, a dedicated voltage for generating the operating voltage of the driving unit 54 is used. This eliminates the need for a separate booster circuit, which facilitates downsizing and reduction in the number of components.

  However, in the configuration in which the operating voltage of the drive unit 54 that drives the voltage conversion unit 40 is generated based on the output of the driven voltage conversion unit 40, when the drive unit 54 does not operate the voltage conversion unit 40 (that is, There is a problem that the operating voltage cannot be supplied to the driving unit 54 when the boosting operation according to the control of the driving unit 54 is not performed. That is, if the voltage conversion unit 40 cannot be operated in a situation where the drive unit 54 is not operating, “the operation of the drive unit 54 using the boosting operation of the voltage conversion unit 40 driven by the drive unit 54” will be described. It is not possible to shift to the operation of “generating a voltage”. This configuration also eliminates this problem, and the control signal output from the control unit 39 can be amplified by the amplification unit 56 and output to the switching element (specifically, the low-side semiconductor switch element 44). It is like that. That is, since the switching element can be operated by the amplifying unit 56 even when the driving unit 54 is not operating, the above problem is solved.

  In the power supply device 30, the first power supply section 91 and the load 94 are electrically connected, and the first conductive path 31 to which the output voltage from the voltage conversion section 40 is applied in the boost mode and the second power supply section 92 are electrically connected. And a second conductive path 32 to which an input voltage to the voltage conversion unit 40 is applied in the step-up mode. For example, the power supply device 30 configured as described above is configured to the load 94 that is electrically connected to the first power supply unit 91 when power cannot be normally supplied from the first power supply unit 91 to the load 94. The power from the second power supply unit 92 can be supplied after voltage conversion. That is, the second power supply unit 92 can be used as a backup power supply. In addition, when the second power supply unit 92 is used as a backup power supply, it is possible to boost the input voltage from the second power supply unit 92 side and generate an operating voltage to be applied to the drive unit 54. Even when the output voltage of the second power supply unit 92 is low, the driving unit 54 can be operated.

  The amplifying unit 56 is configured to amplify the control signal using the power supply voltage output from the second power supply unit 92 as an operating voltage. The power supply device 30 configured as described above is the second power supply unit even at the time before the control of the voltage conversion unit 40 by the drive unit 54 is started (that is, the time when the drive unit 54 is not operating). The control signal output from the control unit 39 can be amplified using the power supply voltage 92, and appropriate on and off voltages can be applied to the switching elements of the voltage conversion unit 40.

  The voltage conversion unit 40 is configured as a switching element and electrically connected to the first conductive path 31, and is configured as a switching element and electrically connected to the semiconductor switch element 42. The semiconductor switch element 44 (second MOSFET) connected to each other and one end between the semiconductor switch element 42 and the semiconductor switch element 44 are electrically connected and the other end is electrically connected to the second conductive path 32. The coil part 46 is provided. In the semiconductor switch element 42, a diode (parasitic diode 42 </ b> A) that allows energization from the coil portion 46 side to the first conductive path 31 side is arranged. Based on a control signal from the control unit 39, the drive unit 54 outputs first signal to the semiconductor switch element 42 and outputs off signal to the semiconductor switch element 44, and to the semiconductor switch element 42. The second control for outputting the off signal and outputting the on signal to the semiconductor switch element 44 can be switched. The amplifying unit 56 can output an amplified signal obtained by amplifying the control signal to the semiconductor switch element 44. According to this configuration, when the drive unit 54 cannot be driven, the amplifying unit 56 performs the switching operation of the semiconductor switch element 44 and uses the diode of the semiconductor switch element 42 that has been turned off (parasitic diode 42A). Step-up operation can be performed. In addition, when the boost operation of the voltage conversion unit 40 progresses and the drive unit 54 can be driven, the semiconductor switch element 42 and the semiconductor switch element 44 can both be turned on and off by the drive unit 54. The voltage boosting operation can be performed with the loss suppressed by the method.

  The power supply device 30 inputs a control signal from the control unit 39 to the drive unit 54 when the output voltage from the voltage conversion unit 40 is equal to or greater than a predetermined threshold value, and controls the control signal when the output voltage is less than the predetermined threshold value. Is provided to the amplifier 56. The power supply device 30 configured as described above amplifies the control signal from the control unit 39 when the output from the voltage conversion unit 40 is relatively low and the drive unit 54 is unlikely to operate normally. The voltage converter 40 can be operated by the amplified signal from the amplifier 56. When the output from the voltage conversion unit 40 becomes relatively high and the possibility that the drive unit 54 operates normally increases, a control signal from the control unit 39 is input to the drive unit 54 and the drive unit 54 The voltage converter 40 can be driven by 54.

<Other embodiments>
The present invention is not limited to the first embodiment described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  In the embodiment described above, a lead battery is used for the first power supply unit 91. However, the present invention is not limited to this configuration, and in any example of the present specification, the first power supply unit 91 is used in place of the lead battery or in combination with the lead battery. Other power supply means (other known power storage means, power generation means, etc.) may be used for the power supply unit 91. The number of power supply means configuring the first power supply unit 91 is not limited to one, and may be configured by a plurality of power supply means.

  In the above-described embodiment, the electric double layer capacitor is used for the second power supply unit 92. However, the present invention is not limited to this configuration. In any example of the present specification, the second power supply unit 92 includes a lithium ion battery, a lithium Other power storage means such as an ion capacitor or a nickel metal hydride battery may be used. Further, the number of power storage means configuring the second power supply unit 92 is not limited to one, and may be configured by a plurality of power storage means.

  In the above-described embodiment, the configuration of FIG. 2 is illustrated as an example of the amplifying unit 56, but another known amplifying circuit may be used.

  In the above-described embodiment, the output voltage when the second power supply unit 92 is fully charged is smaller than the output voltage when the first power supply unit 91 is fully charged. However, in any example of the present specification, The output voltage when the second power supply unit 92 is fully charged may be approximately the same as the output voltage when the first power supply unit 91 is fully charged.

  In the above-described embodiment, the first power supply unit 91 and the load 94 are connected to the first conductive path 31. However, the present invention is not limited to this, and other electrical components such as a generator and another load are electrically connected. It may be. Moreover, if the place which connects these electric components is a position electrically connected to the 1st conductive path 31, various positions will be object.

  In the above-described embodiment, an example of detecting an abnormal state has been described. However, for example, in any example, a protection operation can be added. Specifically, the control unit 39 monitors the detection value from the current detection unit 36, and when the current value of the first conductive path 31 becomes equal to or higher than the upper limit current value (current threshold value), the first switch unit 34 and the first The two switch portions 35 may be turned off, and the semiconductor switch element 44 may be turned off. As a result, no current flows from the first power supply unit 91 to the load 94, and no current flows from the second power supply unit 92 to the load 94.

DESCRIPTION OF SYMBOLS 30 ... Power supply device 31 ... 1st conductive path 32 ... 2nd conductive path 39 ... Control part (switching part)
40 ... Voltage converter 42 ... Semiconductor switch element (switching element, first MOSFET)
42A ... Parasitic diode (diode)
44 ... Semiconductor switch element (switching element, second MOSFET)
46 ... Coil part 54 ... Drive part 56 ... Amplification part 58 ... Changeover switch (switching part)
60 ... Control unit 91 ... First power supply unit 92 ... Second power supply unit (power supply unit)
94 ... Load

Claims (5)

A voltage conversion unit that boosts and outputs a voltage input based on the power from the power supply unit by turning on and off the switching element; and
A control unit that outputs a control signal for controlling the operation of the switching element;
When an operating voltage is supplied based on the output voltage output by the voltage boosting operation in the voltage conversion unit and the output voltage is equal to or higher than a predetermined threshold, a drive signal corresponding to the control signal output from the control unit A drive unit that outputs to the switching element;
An amplifier for amplifying the control signal output from the control unit and outputting the amplified control signal to the switching element when the output voltage is less than a predetermined threshold;
A power supply device comprising: A first conductive path to which a first power supply unit and a load are electrically connected and to which the output voltage from the voltage conversion unit is applied;
A second conductive path to which a second power supply unit as the power supply unit is electrically connected and an input voltage to the voltage conversion unit is applied;
The power supply device according to claim 1.   The power supply device according to claim 2, wherein the amplifying unit amplifies the control signal using a power supply voltage output from the second power supply unit as an operating voltage. The voltage conversion unit is configured as the switching element and electrically connected to the first conductive path, and is configured as the switching element and electrically connected to the first MOSFET. The second MOSFET, and a coil portion having one end electrically connected between the first MOSFET and the second MOSFET and the other end electrically connected to the second conductive path, The first MOSFET is provided with a diode that allows energization from the coil part side to the first conductive path side,
The driving unit outputs a first signal to the first MOSFET and outputs a second signal to the second MOSFET based on a control signal from the control unit; Switching between second control for outputting an off signal to the MOSFET and outputting an on signal to the second MOSFET;
The power supply device according to claim 2, wherein the amplifying unit outputs an amplified signal obtained by amplifying the control signal to the second MOSFET.   When the output voltage from the voltage converter is equal to or higher than the predetermined threshold, the control signal from the controller is input to the drive unit, and the output voltage from the voltage converter is less than the predetermined threshold. 5. The power supply device according to claim 1, further comprising a switching unit that inputs the control signal to the amplifying unit.

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