power supply

Abstract

To reduce power consumption at detecting an AC voltage, and to reduce power consumption and circuit scale of a discharge circuit.SOLUTION: A power supply device includes a smoothing capacitor connected between a first DC voltage terminal and a second DC voltage terminal, a bridge circuit including a plurality of switch elements and outputting an output voltage from a first output voltage terminal and a second output voltage terminal, an AC voltage detection part for detecting an AC voltage applied from an external device to the first output voltage terminal and the second output voltage terminal, and a control part for controlling the bridge circuit. The control part outputs the output voltage from the first output voltage terminal and the second output voltage terminal in normal operation. The control part discharges the smoothing capacitor if the operation is in halt and the AC voltage detection part does not detect an AC voltage from the external device. The control part halts the operation of the switch elements of the bridge circuit if the operation is in halt and the AC voltage detection part detects an AC voltage from the external device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power supply device. [Background technology]

[0002] There are known techniques for discharging electric charges accumulated inside electronic devices. For example, Patent Document 1 describes a technique for discharging electric charges accumulated in an internal capacitor by a discharge circuit when the operation of a DC / AC inverter is stopped. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-2943 Summary of the Invention [Problem to be solved by the invention]

[0004] Multiple DC / AC inverters may be connected in parallel for use. In this case, the output voltage of another DC / AC inverter may flow into the output terminal of the DC / AC inverter itself. If the discharge circuit discharges its internal charge while the output voltage of the other DC / AC inverter is flowing in, the discharge circuit will also discharge the output voltage from the other DC / AC inverter, which may increase the load on the discharge circuit.

[0005] An object of the present disclosure is to provide a power supply device that can reduce power consumption when detecting AC voltage and reduce the circuit scale and power consumption of the discharge circuit. [Means for solving the problem]

[0006] A power supply device according to the present disclosure includes: a smoothing capacitor connected between a first DC voltage terminal to which a DC voltage is supplied and a second DC voltage terminal; a bridge circuit including a plurality of switch elements, which converts the DC voltage input from the smoothing capacitor into an AC voltage by switching operations of the switch elements and outputs the AC voltage from a first output voltage terminal and a second output voltage terminal; an AC voltage detection unit electrically connected to the first output voltage terminal and the second output voltage terminal and which detects an AC voltage flowing into the first output voltage terminal and the second output voltage terminal from an external device; and a control unit which controls the bridge circuit. During normal operation, the control unit controls the switch elements of the bridge circuit at a drive frequency within a predetermined range to output the output voltage from the first output voltage terminal and the second output voltage terminal, and when operation is stopped and the AC voltage detection unit does not detect the AC voltage from the external device, controls the switch elements of the bridge circuit at an output stop frequency that is higher than the drive frequency to discharge the smoothing capacitor, and when operation is stopped and the AC voltage detection unit detects the AC voltage from the external device, stops the operation of the switch elements of the bridge circuit.

[0007] The power supply device of the present disclosure includes a discharge circuit including a discharge resistance element and a discharge switch element connected in parallel to the smoothing capacitor, wherein the discharge resistance element has one end electrically connected to the high potential side terminal of the smoothing capacitor and the other end electrically connected to the drain terminal of the discharge switch element, and the discharge switch element has a source terminal electrically connected to the low potential side terminal of the smoothing capacitor, and the control unit, when not operating and when the AC voltage detection unit is not detecting the AC voltage from the external device, controls the discharge switch element to discharge the smoothing capacitor through the discharge resistance element, and when not operating and when the AC voltage detection unit is detecting the AC voltage from the external device, stops the operation of the discharge switch element of the bridge circuit.

[0008] In the power supply device of the present disclosure, when the control unit is stopped, if control power is being supplied from the control power supply, the control unit controls the switch element at an output stop frequency higher than the drive frequency to discharge the smoothing capacitor or controls the discharge switch element to discharge the smoothing capacitor; when the supply of control power from the control power supply is stopped, the control unit uses the control power that has been charged in a storage element such as a capacitor for the discharge operation; if the supply of control power from the control power supply is stopped and the AC voltage detection unit does not detect the AC voltage from the external device, the control unit controls the switch elements of the bridge circuit at an output stop frequency higher than the drive frequency to discharge the smoothing capacitor and controls the discharge switch element to discharge the smoothing capacitor; and if the supply of control power from the control power supply is stopped and the AC voltage detection unit detects the AC voltage from the external device, the control unit stops the operation of the discharge switch element and stops the discharge of the smoothing capacitor.

[0009] In the power supply device of the present disclosure, when the supply of control power from the control power supply is stopped and the AC voltage detection unit detects the AC voltage from the external device, the control unit stops the operation of the discharge switch element or the switch element and stops the discharge of the smoothing capacitor until a higher-level device stops the output of other power supply devices connected in parallel.

[0010] In the power supply device of the present disclosure, the AC voltage detection unit includes a photocoupler, and is configured so that the signal generated based on the output of the photocoupler when detecting AC voltage is a continuous signal.

[0011] In the power supply device of the present disclosure, when normal operation is stopped, the control unit stops operation of the switch elements of the bridge circuit in advance when the AC voltage detection unit detects AC voltage from the external device. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to reduce the power consumption when detecting AC voltage, and also reduce the circuit size and power consumption of the discharge circuit. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a power supply device according to the first embodiment. [Figure 2] FIG. 2 is a flowchart showing the flow of a discharge process according to a first example of the first embodiment. [Figure 3] FIG. 3 is a flowchart showing the flow of a discharge process according to a second example of the first embodiment. [Figure 4] FIG. 4 is a diagram showing an example of the configuration of a power supply system according to the second embodiment. [Figure 5] FIG. 5 is a flowchart showing the flow of a discharge process according to a first example of the second embodiment. [Figure 6] FIG. 6 is a sequence diagram showing the flow of a first example of a discharge process in the power supply system according to the second embodiment. [Figure 7] FIG. 7 is a sequence diagram showing the flow of a second example of a discharge process in the power supply system according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Note that the present disclosure is not limited to these embodiments, and in the following embodiments, the same components are designated by the same reference numerals, and redundant description will be omitted.

[0015] [First embodiment] An example of the configuration of the power supply device according to the first embodiment will be described using Fig. 1. Fig. 1 is a diagram showing an example of the configuration of the power supply device according to the first embodiment.

[0016] As shown in FIG. 1, the power supply device 1 includes a first DC voltage terminal 11, a second DC voltage terminal 12, a smoothing capacitor 20, a discharge circuit 30, a bridge circuit 40, a filter circuit 50, a first output voltage terminal 61, a second output voltage terminal 62, an AC voltage detection unit 70, an AND gate 80, and a control unit 90.

[0017] The first DC voltage terminal 11 is electrically connected to a high-potential terminal of a DC / DC converter (not shown), and the second DC voltage terminal 12 is electrically connected to a low-potential terminal of the DC / DC converter (not shown).

[0018] One end of smoothing capacitor 20 is electrically connected to first DC voltage terminal 11. The other end of smoothing capacitor 20 is electrically connected to second DC voltage terminal 12. Smoothing capacitor 20 smoothes the voltage input to first DC voltage terminal 11 and second DC voltage terminal 12.

[0019] One end of the discharge circuit 30 is electrically connected to the first DC voltage terminal 11. The other end of the discharge circuit 30 is electrically connected to the second DC voltage terminal 12. The discharge circuit 30 includes a resistance element 31 and a switch element 32.

[0020] One end of the resistance element 31 is electrically connected to the first DC voltage terminal 11. The other end of the resistance element 31 is electrically connected to the drain terminal of the switch element 32. The resistance element 31 is also called a discharge resistance element.

[0021] The drain terminal of the switch element 32 is electrically connected to the other end of the resistor element 31. The source terminal of the switch element 32 is electrically connected to the second DC voltage terminal 12. That is, the resistor element 31 and the switch element 32 are connected in parallel to the smoothing capacitor 20. The on and off states of the switch element 32 are controlled by the control unit 90. The switch element 32 is sometimes called a discharge switch element. The switch element 32 is, for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), but is not limited to this. The switch element 32 may also be a silicon power device, a GaN power device, a SiC power device, an IGBT (Insulated Gate Bipolar Transistor), or the like.

[0022] The switch element 32 has a parasitic diode (body diode). A parasitic diode is a pn junction between the back gate and the source and drain of a MOSFET. The parasitic diode can be used as a freewheeling diode to release transient back electromotive force when the transistor is turned off. In addition to the parasitic diode, a diode element may be added between the drain and source of each transistor.

[0023] The bridge circuit 40 includes a switch element 41, a switch element 42, a switch element 43, and a switch element 44. The bridge circuit 40 is a full-bridge circuit. The on and off states of the switch elements 41 to 44 are controlled by the control unit 90.

[0024] The drain terminal of the switch element 41 is electrically connected to the high potential side of the smoothing capacitor 20. The source terminal of the switch element 41 is electrically connected to the drain terminal of the switch element .

[0025] The drain terminal of the switch element 42 is electrically connected to the source terminal of the switch element 41. The source terminal of the switch element 42 is electrically connected to the low potential side of the smoothing capacitor 20.

[0026] The connection between the source terminal of the switch element 41 and the drain terminal of the switch element 42 forms a first output part of the bridge circuit 40.

[0027] The drain terminal of the switch element 43 is electrically connected to the high potential side of the smoothing capacitor 20. The source terminal of the switch element 43 is electrically connected to the drain terminal of the switch element .

[0028] The drain terminal of the switch element 44 is electrically connected to the source terminal of the switch element 43. The source terminal of the switch element 44 is electrically connected to the low potential side of the smoothing capacitor 20.

[0029] The connection between the source terminal of the switch element 43 and the drain terminal of the switch element 44 forms a second output part of the bridge circuit 40.

[0030] The switch elements 41 to 44 are, for example, but not limited to, MOSFETs. The switch elements 41 to 44 may also be silicon power devices, GaN power devices, SiC power devices, IGBTs, etc. The switch elements 41 to 44 have parasitic diodes (body diodes).

[0031] The filter circuit 50 includes a choke coil 51, a choke coil 52, and a capacitor 53. The filter circuit 50 is a low-pass filter.

[0032] One end of the choke coil 51 is electrically connected to the first output part of the bridge circuit 40. The other end of the choke coil 51 is electrically connected to the first output voltage terminal 61.

[0033] One end of the choke coil 52 is electrically connected to the second output part of the bridge circuit 40. The other end of the choke coil 52 is electrically connected to the second output voltage terminal 62.

[0034] One end of the capacitor 53 is electrically connected between the other end of the choke coil 51 and the first output voltage terminal 61. The other end of the capacitor 53 is electrically connected between the other end of the choke coil 52 and the second output voltage terminal 62.

[0035] The first output voltage terminal 61 and the second output voltage terminal 62 are electrically connected to an arbitrary load.

[0036] The AC voltage detection unit 70 includes a photocoupler 71, a resistive element 72, and a capacitor 73. The AC voltage detection unit 70 is configured to detect the AC voltages flowing in from the first output voltage terminal 61 and the second output voltage terminal 62.

[0037] The photocoupler 71 includes a light-emitting element 71a and a phototransistor 71b. The light-emitting element 71a emits light when AC current flows from the first output voltage terminal 61 and the second output voltage terminal 62 via a resistive element 72 and a capacitor 73. When the light-emitting element 71a emits light, the phototransistor 71b switches from an OFF state to an ON state. This causes the AC voltage detection unit 70 to detect AC voltage. When the photocoupler 71 detects AC voltage, it outputs a detection signal S1 to the AND gate 80 and a detection signal S2 to the control unit 90. The photocoupler 71 outputs a continuous signal while detecting AC voltage.

[0038] The detection signal S1 and the detection signal S2 are the same signal. The detection signal S1 and the detection signal S2 are at a low level when an AC voltage is detected. The detection signal S1 and the detection signal S2 are at a high level when no AC voltage is detected.

[0039] One input terminal of the photocoupler 71 is electrically connected to the first output voltage terminal 61. A capacitor 73 is connected in series between the one input terminal of the photocoupler 71 and the first output voltage terminal 61.

[0040] The other input terminal of the photocoupler 71 is electrically connected to the second output voltage terminal 62. A resistive element 72 is connected in series between the other input terminal of the photocoupler 71 and the second output voltage terminal 62.

[0041] A capacitor 73 and a resistive element 72 may be connected in series between one input terminal of the photocoupler 71 and the first output voltage terminal 61, or a capacitor 73 and a resistive element 72 may be connected in series between the other input terminal of the photocoupler 71 and the second output voltage terminal 62.

[0042] One output terminal of the photocoupler 71 is processed into a continuous signal and electrically connected to one input terminal of an AND gate 80 and the control unit 90. The other output terminal of the photocoupler 71 is electrically connected to the GND of the control unit 90.

[0043] One input terminal of the AND gate 80 is electrically connected to one input terminal of the photocoupler 71. A detection signal S1 from the photocoupler 71 is input to one input terminal of the AND gate 80. A control unit 90 is electrically connected to the other input terminal of the AND gate 80. A drive signal S4 from the control unit is input to the other input terminal of the AND gate 80. An output terminal of the AND gate 80 is electrically connected to the gate terminal of the switch element 32 of the discharge circuit 30.

[0044] The control unit 90 controls the discharge circuit 30 and the bridge circuit 40. The control unit 90 includes, for example, an information processing device such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and a storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory). The control unit 90 may be realized by, for example, an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The control unit 90 may also be realized by a combination of hardware and software.

[0045] The control unit 90 includes an AC voltage detection unit 91 , a bridge circuit control unit 92 , and a discharge circuit control unit 93 .

[0046] The AC voltage detection unit 91 detects an AC voltage having a value equal to or greater than a predetermined value based on the detection result of the AC voltage detection unit 70. When the AC voltage detection unit 91 detects an AC voltage having a value equal to or greater than a predetermined value, it outputs a detection signal indicating this to the bridge circuit control unit 92 and the discharge circuit control unit 93.

[0047] The bridge circuit control unit 92 controls the bridge circuit 40. The bridge circuit control unit 92 controls the bridge circuit 40 by outputting a drive signal S3 to the bridge circuit 40. The bridge circuit control unit 92 switches the on and off states of switch elements 41 to 44 included in the bridge circuit 40. During normal operation, the bridge circuit control unit 92 controls switch elements 41 to 44 at a drive frequency within a predetermined range to output output voltages from the first output voltage terminal 61 and the second output voltage terminal 62. During normal operation, when the AC voltage detection unit 70 does not detect AC voltage from an external device, the bridge circuit control unit 92 controls switch elements 41 to 44 to discharge the charge accumulated in the smoothing capacitor 20. During normal operation, when the AC voltage detection unit 70 detects AC voltage from an external device, the bridge circuit control unit 92 preferably stops the operation of switch elements 41 to 44. The process in which the bridge circuit control unit 92 controls the switch elements 41 to 44 to discharge the smoothing capacitor 20 will be described in detail later.

[0048] The discharge circuit control unit 93 controls the discharge circuit 30. The discharge circuit control unit 93 controls the discharge circuit 30 by outputting a drive signal S4 to the discharge circuit 30. The discharge circuit control unit 93 controls the switch element 32 of the discharge circuit 30 to discharge the charge accumulated in the smoothing capacitor 20. The process in which the discharge circuit control unit 93 controls the switch element 32 to discharge the charge accumulated in the smoothing capacitor 20 will be described in detail later.

[0049] [Discharge treatment] Next, the discharge process according to the first embodiment will be described. In FIG. 1, an AC voltage may flow into the first output voltage terminal 61 and the second output voltage terminal 62 from an external device. While AC voltage is flowing in, the smoothing capacitor 20 continues to be charged, making it impossible to discharge the smoothing capacitor 20. If the smoothing capacitor 20 were to be discharged in this state, the discharge power would be large. Therefore, the discharge operation of the smoothing capacitor 20 while AC voltage is flowing in cannot limit the discharge power, and the discharge capacity setting of the discharge circuit cannot be determined. Therefore, in the first embodiment, a process is performed to stop the discharge process while AC voltage is flowing in the first output voltage terminal 61 and the second output voltage terminal 62.

[0050] (First example) The discharge process according to the first example of the first embodiment will be described with reference to Fig. 2. Fig. 2 is a flowchart showing the flow of the discharge process according to the first example of the first embodiment.

[0051] The discharge process according to the first example of the first embodiment is a process in which the control unit 90 controls the bridge circuit 40 to discharge the charge accumulated in the smoothing capacitor 20.

[0052] The control unit 90 determines whether the power supply unit in which the power supply unit 1 is installed is operating (step S10). If it is determined that the power supply unit in which the power supply unit 1 is installed is operating (step S10; Yes), the process proceeds to step S12. If it is determined that the power supply unit in which the power supply unit 1 is installed is stopped (step S10; No), the process proceeds to step S14.

[0053] If the determination in step S10 is Yes, the bridge circuit control unit 92 controls the switch elements 41 to 44 of the bridge circuit 40 at a drive frequency within a predetermined range to output an output voltage from the first output voltage terminal 61 and the second output voltage terminal 62 (step S12). Then, the process proceeds to step S10. That is, the bridge circuit control unit 92 continues the operation of causing the bridge circuit 40 to output an output voltage during operation.

[0054] If the determination in step S10 is No, the AC voltage detection unit 91 determines whether or not an AC voltage has been detected (step S14). Specifically, the AC voltage detection unit 91 detects the AC voltage based on a detection signal from the AC voltage detection unit 70. When discharging the smoothing capacitor 20, the AC voltage detection unit 91 constantly determines whether or not an AC voltage has been detected. If an AC voltage has been detected (step S14; Yes), the process proceeds to step S16. If an AC voltage has not been detected (step S14; No), the process proceeds to step S18.

[0055] If the determination in step S14 is Yes, the bridge circuit control unit 92 stops the operation of the switch elements 41 to 44 of the bridge circuit 40 (step S16). In other words, the bridge circuit control unit 92 turns off all of the switch elements 41 to 44. Then, the process proceeds to step S14.

[0056] If the determination in step S14 is No, the bridge circuit control unit 92 controls the bridge circuit 40 to discharge the smoothing capacitor 20 (step S18). Specifically, the bridge circuit control unit 92 drives the switch elements 41 to 44 at an output stop frequency that is higher than the drive frequency during operation, thereby discharging the smoothing capacitor 20. Then, the processing in FIG. 2 ends.

[0057] (Second example) A discharge process according to the second example of the first embodiment will be described with reference to Fig. 3. Fig. 3 is a flowchart showing the flow of the discharge process according to the second example of the first embodiment.

[0058] The discharge process according to the second example of the first embodiment is a process in which the control unit 90 controls the discharge circuit 30 to discharge the charge accumulated in the smoothing capacitor 20.

[0059] The processing from step S30 to step S34 is the same as the processing from step S10 to step S14 shown in FIG. 2, and therefore a description thereof will be omitted.

[0060] If the determination in step S34 is Yes, the discharge circuit control unit 93 stops the operation of the switch element 32 of the discharge circuit 30 (step S36). In other words, the discharge circuit control unit 93 turns off the switch element 32. Then, the process proceeds to step S34.

[0061] If the determination in step S34 is No, the discharge circuit control unit 93 controls the discharge circuit 30 to discharge the smoothing capacitor 20 (step S38). Specifically, the discharge circuit control unit 93 switches the switch element 32 of the discharge circuit 30 to the ON state, causing the charge accumulated in the smoothing capacitor 20 to be discharged through the discharge resistor 21. More specifically, the discharge circuit control unit 93 outputs a low-level drive signal S4 to the AND gate 80 when an AC voltage is detected except when an output stop operation is performed during operation. The discharge circuit control unit 93 outputs a high-level drive signal S4 to the AND gate 80 when an AC voltage is not detected when an output stop operation is performed during operation. That is, when an AC current is not detected, a high-level detection signal S1 is input from the AC voltage detection unit 70 to one input terminal of the AND gate 80, and a high-level drive signal S4 is input from the discharge circuit control unit 93 to the other input terminal for a certain period of time after an output stop operation is performed during operation. As a result, the AND gate 80 outputs a high-level drive signal S5 to the switch element 32. The switch element 32 is switched to the ON state by the high-level drive signal S5 from the AND gate 80. This allows the discharge circuit 30 to discharge the charge accumulated in the smoothing capacitor 20 via the resistance element 31. Then, the processing in FIG. 3 ends.

[0062] As described above, in the first embodiment, the smoothing capacitor 20 does not discharge until the AC voltage from the other power supply device is stopped. This allows the first embodiment to limit the discharge power during the discharge operation to the charge stored in the internal capacitor.

[0063] Specifically, in the first embodiment, the discharge power during the discharge operation is limited to the power stored in the internal capacitor, thereby making it possible to reduce the size of the discharge circuit 30.

[0064] Furthermore, in the first embodiment, power consumption can be reduced by detecting the output voltage from the other power supply device connected in parallel with the AC voltage detection unit 70. As a result, in the first embodiment, the discharge circuit 30 can be placed in a standby state until the output voltage from the other power supply device stops, so that the standby state can be achieved while suppressing power consumption.

[0065] [Second embodiment] Next, a second embodiment of the present disclosure will be described.

[0066] In the first embodiment, the description has been given assuming that there is only one power supply device 1. In the present disclosure, for example, a plurality of power supply devices 1 may be connected in parallel. Fig. 4 is a diagram showing an example of the configuration of a power supply system according to a second embodiment.

[0067] As shown in Fig. 4, the power supply system 100 includes a power supply device 1a, a power supply device 1b, and a higher-level device 110. The power supply devices 1a and 1b are connected in parallel. In the example shown in Fig. 4, the power supply system 100 shows an example in which two power supply devices are connected in parallel, but the present disclosure is not limited to this. The power supply system 100 may also have three or more power supply devices connected in parallel.

[0068] In the example shown in Fig. 4, AC current from power supply device 1b may flow into the first output voltage terminal 61 and the second output voltage terminal 62 of power supply device 1a. In other words, power supply device 1b is an external device from the perspective of power supply device 1a. AC current from power supply device 1b may flow into the first output voltage terminal 61 and the second output voltage terminal 62 of power supply device 1b. In other words, power supply device 1a is an external device from the perspective of power supply device 1b.

[0069] The upper level device 110 is a control device that controls the power supply system 100. The upper level device 110 is, for example, an ECU (Engine Control Unit), but is not limited to this. The upper level device 110 monitors the power supply device 1a and the power supply device 1b. The upper level device 110 controls the power supply device 1a and the power supply device 1b. The upper level device 110 controls the power supply device 1a and the power supply device 1b by outputting control power to the power supply device 1a and the power supply device 1b.

[0070] The discharge process according to the second embodiment will be described with reference to Fig. 5. Fig. 5 is a flowchart showing the flow of the discharge process according to the second embodiment.

[0071] The discharge process according to the second embodiment changes the discharge operation depending on the presence or absence of control power from the higher-level device 110. In the example shown in Fig. 5, the process when the higher-level device 110 monitors the power supply device 1a will be described.

[0072] The processes in steps S50 and S52 are the same as the processes in steps S10 and S12 shown in FIG. 2, respectively, and therefore will not be described here.

[0073] If the determination in step S50 is No, the control unit 90 determines whether or not control power is being supplied from the higher-level device 110 (step S54). If it is determined that control power is being supplied (step S54; Yes), the process proceeds to step S56. If it is not determined that control power is not being supplied (step S54; No), the process proceeds to step S58.

[0074] If the determination in step S54 is Yes, the control unit 90 determines that the control power from the higher-level device 110 is to be used for the discharging operation (step S56), and then the process proceeds to step S60.

[0075] If step S54 returns No, the control unit 90 determines that the power stored in a storage element such as a capacitor will be used for the discharge operation (step S58). The storage element is provided, for example, in the control unit 90. The control unit 90 may store power in the storage element, for example, when control power is being supplied from the higher-level device 110. In this case, discharge by the discharge circuit 30 can be performed with less power than discharge by the bridge circuit 40. The discharge circuit 30 is a circuit that can be realized with a small power storage element and serves as a discharge means for when the control power supply is lost. Then, the process proceeds to step S60.

[0076] The process of step S60 is the same as the process of step S14 shown in FIG. 2, and therefore a description thereof will be omitted.

[0077] If the determination in step S60 is Yes, the control unit 90 stops the operation of switch element 41 to switch element 44 of the bridge circuit 40 or switch element 32 of the discharge circuit 30 (step S62). In other words, the bridge circuit control unit 92 turns off all of switch element 41 to switch element 44. Alternatively, the discharge circuit control unit 93 turns off switch element 32. Then, the process proceeds to step S60.

[0078] If the determination in step S60 is No, the control unit 90 controls the bridge circuit 40 or the discharge circuit 30 to discharge the smoothing capacitor 20 (step S64). Specifically, the bridge circuit control unit 92 drives the switch elements 41 to 44 at an output stop frequency that is higher than the drive frequency during operation, thereby discharging the smoothing capacitor 20. The discharge circuit control unit 93 switches the switch element 32 of the discharge circuit 30 to the ON state, and discharges the charge accumulated in the smoothing capacitor 20 through the discharge resistor 21. Then, the processing of FIG. 5 ends.

[0079] (First example) The flow of a first example of a discharge process in the power supply system according to the second embodiment will be described with reference to Fig. 6. Fig. 6 is a sequence diagram showing the flow of a first example of a discharge process in the power supply system according to the second embodiment.

[0080] The first example of discharge processing in the power supply system according to the second embodiment is processing that is executed when an abnormality occurs in the power supply device 1a and the operation stops.

[0081] Power supply device 1a detects an abnormal temperature above a specified level, and stops output (step S70). Since power supply device 1a detects the AC voltage output from power supply device 1b, power supply device 1a enters a standby state for discharge (step S72). Power supply device 1a sends an abnormality signal indicating that an abnormality has occurred to host device 110 (step S74).

[0082] The host device 110 receives the abnormality signal sent by the power supply device 1a (step S76). Upon receiving the abnormality signal, the host device 110 sends an instruction to stop operation to the power supply device 1b (step S78).

[0083] The power supply device 1b receives the operation stop instruction sent by the higher-level device 110 (step S80). Upon receiving the operation stop instruction, the power supply device 1b stops output (step S82).

[0084] Since power supply device 1a is stopped and no AC voltage is detected, power supply device 1b starts a discharging operation (step S84). Since power supply device 1b is stopped and no AC voltage is detected, power supply device 1a starts a discharging operation (step S86).

[0085] As described above, if the operation of power supply device 1a stops, the operation of power supply device 1b can be stopped by instruction from higher-level device 110, thereby improving safety when performing a discharging operation.

[0086] (Second example) The flow of a second example of a discharge process in the power supply system according to the second embodiment will be described with reference to Fig. 7. Fig. 7 is a sequence diagram showing the flow of a second example of a discharge process in the power supply system according to the second embodiment.

[0087] The second example of discharge processing in the power supply system according to the second embodiment is processing that is executed when the control power of the power supply device 1a is lost.

[0088] The power supply device 1a stops outputting due to loss of control power (step S90). For example, the power supply device 1a loses control power due to a disconnection of the harness connecting the power supply device 1a and the control power supply.

[0089] The processes from step S92 to step S102 are the same as the processes from step S72 to step S82 shown in FIG. 6, respectively, and therefore will not be described here.

[0090] Since power supply device 1a is stopped, AC voltage is not detected and control power is not lost, so power supply device 1b starts a discharge operation using the control power (step S104). Since power supply device 1b is stopped, AC voltage is not detected and control power is lost, so power supply device 1a starts a discharge operation using the power stored in the storage element (step S106).

[0091] As described above, in the second embodiment, the smoothing capacitor 20 is not discharged until the AC voltage from the other power supply device is stopped. This reduces the power consumption for controlling each switch element, so that even if the supply of control power to the higher-level device 110 is stopped, each switch element can secure power for discharging the smoothing capacitor 20 after the AC voltage from the other power supply device is stopped.

[0092] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the contents of these embodiments. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments. [Explanation of symbols]

[0093] 1 Power supply 11 First DC voltage terminal 12 Second DC voltage terminal 20 smoothing capacitor 30 Discharge circuit 31,72 Resistive element 32, 41, 42, 43, 44 Switch elements 40 Bridge Circuit 50 Filter circuit 51,52 Choke coil 53,73 Capacitor 61 First output voltage terminal 62 Second output voltage terminal 70 AC voltage detection section 71 Photocoupler 71a Light-emitting part 71b Phototransistor 80 AND Gate 90 Control Unit 91 AC voltage detection unit 92 Bridge circuit control section 93 Discharge circuit control section

Claims

1. a smoothing capacitor connected between a first DC voltage terminal to which a DC voltage is supplied and a second DC voltage terminal; a bridge circuit including a plurality of switch elements, which converts the DC voltage input from the smoothing capacitor into an AC voltage by switching operations of the switch elements, and outputs the AC voltage as an output voltage from a first output voltage terminal and a second output voltage terminal; an AC voltage detection unit electrically connected to the first output voltage terminal and the second output voltage terminal, and detecting an AC voltage flowing into the first output voltage terminal and the second output voltage terminal from an external device; a control unit that controls the bridge circuit, The control unit During normal operation, the switch elements of the bridge circuit are controlled at a drive frequency within a predetermined range to output the output voltage from the first output voltage terminal and the second output voltage terminal; When the inverter is stopped and the AC voltage detection unit does not detect the AC voltage from the external device, the inverter controls the switch elements of the bridge circuit at an output stop frequency that is higher than the drive frequency to discharge the smoothing capacitor; When the operation is stopped and the AC voltage detection unit detects the AC voltage from the external device, the operation of the switch elements of the bridge circuit is stopped. power supply.

2. a discharge circuit including a discharge resistance element and a discharge switch element connected in parallel to the smoothing capacitor; one end of the discharge resistance element is electrically connected to the high potential side terminal of the smoothing capacitor, and the other end is electrically connected to the drain terminal of the discharge switch element; the discharge switch element has a source terminal electrically connected to a low potential side terminal of the smoothing capacitor, The control unit When the operation is stopped and the AC voltage detection unit does not detect the AC voltage from the external device, the discharge switch element is controlled to discharge the smoothing capacitor through the discharge resistor element; When the operation is stopped and the AC voltage detection unit detects the AC voltage from the external device, the operation of the discharge switch element of the bridge circuit is stopped. The power supply device of claim 1 .

3. When the control unit stops operating, When control power is supplied from a control power supply, the switch element is controlled at an output stop frequency higher than the drive frequency to discharge the smoothing capacitor, or the discharge switch element is controlled to discharge the smoothing capacitor; When the supply of control power from the control power supply is stopped, the control power charged in the storage element is used for discharging operation; when the supply of control power from the control power supply is stopped and the AC voltage detection unit does not detect the AC voltage from the external device, the switch elements of the bridge circuit are controlled at an output stop frequency that is higher than the drive frequency to discharge the smoothing capacitor, or the discharge switch elements are controlled to discharge the smoothing capacitor; When the supply of control power from the control power supply is stopped and the AC voltage detection unit detects the AC voltage from the external device, the operation of the discharge switch element is stopped and the discharge of the smoothing capacitor is stopped. The power supply device according to claim 2 .

4. When the supply of control power from the control power supply is stopped and the AC voltage detection unit detects the AC voltage from the external device, the control unit stops operation of the discharge switch element or the switch element and stops discharging of the smoothing capacitor until a higher-level device stops output of another power supply device connected in parallel. The power supply device according to claim 3.

5. The AC voltage detection unit includes a photocoupler, and is configured so that a signal generated based on an output of the photocoupler when detecting an AC voltage becomes a continuous signal. The power supply device according to any one of claims 1 to 4.

6. the control unit stops operation of the switch elements of the bridge circuit in advance when the AC voltage detection unit detects the AC voltage from the external device during normal operation stop. The power supply device according to claim 1 or 5.

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