JP7720240B2 - power supply - Google Patents

Description

This disclosure relates to a power supply device.

Technologies for discharging electric charges accumulated inside electronic devices are known. For example, Patent Document 1 describes a technology in which electric charges accumulated in an internal capacitor are discharged using a discharge circuit when the operation of a DC/AC inverter is stopped.

Japanese Patent Application Laid-Open No. 2021-2943

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.

The objective of this disclosure is to provide a power supply device that reduces power consumption when detecting AC voltage and reduces the circuit size and power consumption of the discharge circuit.

The power supply device disclosed herein comprises: 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 that converts the DC voltage input from the smoothing capacitor into an AC voltage through the switching operation 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 that detects the AC voltage flowing into the first output voltage terminal and the second output voltage terminal from an external device; and a control unit that 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; when operation is stopped and the AC voltage detection unit is not detecting 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 when operation is stopped and the AC voltage detection unit is detecting the AC voltage from the external device, the control unit stops operation of the switch elements of the bridge circuit.

The power supply device of the present disclosure includes a discharge circuit connected in parallel to the smoothing capacitor, the discharge resistance element having one end electrically connected to the high-potential terminal of the smoothing capacitor and the other end electrically connected to the drain terminal of the discharge switch element, and the source terminal of the discharge switch element being electrically connected to the low-potential terminal of the smoothing capacitor. 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 operation of the discharge switch element of the bridge circuit.

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 charged in a storage element such as a capacitor for the discharge operation. When the supply of control power from the control power supply is stopped and the AC voltage detection unit is not detecting the AC voltage from the external device, the control unit controls the switch element 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. When the supply of control power from the control power supply is stopped and the AC voltage detection unit is detecting the AC voltage from the external device, the control unit stops operation of the discharge switch element and stops discharging the smoothing capacitor.

In the power supply device disclosed herein, 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 the output of other power supply devices connected in parallel.

In the power supply device disclosed herein, the AC voltage detection unit includes a photocoupler and is configured so that the signal generated based on the photocoupler output when AC voltage is detected is a continuous signal.

In the power supply device disclosed herein, 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.

This disclosure makes it possible to reduce power consumption when detecting AC voltage, and also to reduce the circuit size and power consumption of the discharge circuit.

FIG. 1 is a diagram illustrating an example of the configuration of a power supply device according to the first embodiment. FIG. 2 is a flowchart showing the flow of the discharge process according to the first example of the first embodiment. FIG. 3 is a flowchart showing the flow of a discharge process according to a second example of the first embodiment. FIG. 4 is a diagram showing an example of the configuration of a power supply system according to the second embodiment. FIG. 5 is a flowchart showing the flow of a discharge process according to a first example of the second embodiment. 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. 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.

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that the present disclosure is not limited to these embodiments, and in the following embodiments, identical components will be designated by the same reference numerals, and redundant explanations will be omitted.

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

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.

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

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

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 resistive element 31 and a switch element 32.

One end of the resistor element 31 is electrically connected to the first DC voltage terminal 11. The other end of the resistor element 31 is electrically connected to the drain terminal of the switch element 32. The resistor element 31 is sometimes called a discharge resistor element.

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), etc.

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.

Bridge circuit 40 includes switch element 41, switch element 42, switch element 43, and switch element 44. Bridge circuit 40 is a full bridge circuit. Switch elements 41 to 44 are each controlled to be in an on or off state by control unit 90.

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

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

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

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

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

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

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

Filter circuit 50 includes choke coil 51, choke coil 52, and capacitor 53. Filter circuit 50 is a low-pass filter.

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

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

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

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

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 voltage flowing in from the first output voltage terminal 61 and the second output voltage terminal 62.

The photocoupler 71 includes a light-emitting element 71a and a phototransistor 71b. The light-emitting element 71a emits light when AC current flows in from the first output voltage terminal 61 and the second output voltage terminal 62 via the resistor element 72 and 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.

Detection signal S1 and detection signal S2 are the same signal. Detection signal S1 and detection signal S2 are low level when AC voltage is detected. Detection signal S1 and detection signal S2 are high level when AC voltage is not detected.

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.

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.

A capacitor 73 and a resistor 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 resistor element 72 may be connected in series between the other input terminal of the photocoupler 71 and the second output voltage terminal 62.

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

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.

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 implemented using 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 implemented using a combination of hardware and software.

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

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

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 predetermined drive frequency range to output an output voltage 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 switch elements 41 to 44 to discharge the smoothing capacitor 20 will be described in detail below.

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. Details of the process by 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 later.

[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.

(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.

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.

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

If step S10 returns Yes, the bridge circuit control unit 92 controls 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 to cause the bridge circuit 40 to output an output voltage while in operation.

If step S10 returns No, the AC voltage detection unit 91 determines whether AC voltage has been detected (step S14). Specifically, the AC voltage detection unit 91 detects AC voltage based on the detection signal from the AC voltage detection unit 70. When discharging the smoothing capacitor 20, the AC voltage detection unit 91 constantly determines whether AC voltage has been detected. If AC voltage is detected (step S14; Yes), proceed to step S16. If AC voltage is not detected (step S14; No), proceed to step S18.

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

If step S14 returns 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 switch elements 41 to 44 at an output stop frequency that is higher than the operating drive frequency, thereby discharging the smoothing capacitor 20. The process of FIG. 2 then ends.

(Second Example)
The 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.

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.

The processing from steps S30 to S34 is the same as the processing from steps S10 to S14 shown in Figure 2, so a description thereof will be omitted.

If step S34 returns 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 the switch element 32 off. Then, the process proceeds to step S34.

If step S34 returns 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 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 AC voltage is not detected when an output stop operation is performed during operation. In other words, when 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, AND gate 80 outputs a high-level drive signal S5 to switch element 32. Switch element 32 is switched to the ON state by the high-level drive signal S5 from AND gate 80. This allows discharge circuit 30 to discharge the charge accumulated in smoothing capacitor 20 via resistor element 31. The processing in Figure 3 then ends.

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.

Specifically, the first embodiment limits the discharge power during discharge operation to the power stored in the internal capacitor, thereby reducing the size of the discharge circuit 30.

In addition, in the first embodiment, the output voltage from another power supply device connected in parallel is detected by the AC voltage detection unit 70, thereby reducing power consumption. 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, allowing standby while reducing power consumption.

Second Embodiment
Next, a second embodiment of the present disclosure will be described.

In the first embodiment, only one power supply device 1 is described. In the present disclosure, for example, multiple power supply devices 1 may be connected in parallel. Figure 4 is a diagram showing an example configuration of a power supply system according to a second embodiment.

As shown in FIG. 4, power supply system 100 includes power supply unit 1a, power supply unit 1b, and upper unit 110. Power supply unit 1a and power supply unit 1b are connected in parallel. In the example shown in FIG. 4, power supply system 100 shows an example in which two power supply units are connected in parallel, but the present disclosure is not limited to this. Power supply system 100 may also have three or more power supply units connected in parallel.

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

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

The discharge process according to the second embodiment will be described using Figure 5. Figure 5 is a flowchart showing the flow of the discharge process according to the second embodiment.

The discharge process in the second embodiment changes the discharge operation depending on whether or not control power is received from the host device 110. In the example shown in Figure 5, the process when the host device 110 monitors the power supply device 1a is described.

The processing in steps S50 and S52 is the same as the processing in steps S10 and S12 shown in Figure 2, respectively, and therefore will not be described here.

If step S50 returns No, the control unit 90 determines whether 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 being supplied (step S54; No), the process proceeds to step S58.

If step S54 returns Yes, the control unit 90 determines that the control power from the higher-level device 110 will be used for the discharge operation (step S56). Then, the process proceeds to step S60.

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, discharging by the discharge circuit 30 can be performed with less power than discharging by the bridge circuit 40. The discharge circuit 30 is a circuit that can be implemented with a small power storage element and serves as a discharge means in case the control power supply is lost. Then, proceed to step S60.

The processing in step S60 is the same as the processing in step S14 shown in Figure 2, so its explanation will be omitted.

If step S60 returns Yes, the control unit 90 stops the operation of switch elements 41 to 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 switch elements 41 to 44. Alternatively, the discharge circuit control unit 93 turns off switch element 32. Then, the process proceeds to step S60.

If step S60 returns 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 switch elements 41 to 44 at an output stop frequency that is higher than the operating drive frequency, thereby discharging the smoothing capacitor 20. The discharge circuit control unit 93 switches switch element 32 of the discharge circuit 30 to the ON state, thereby discharging the charge accumulated in the smoothing capacitor 20 through the discharge resistor 21. The processing of FIG. 5 then ends.

(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.

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 operation stops.

Power supply unit 1a stops output when an abnormal temperature above a specified level is detected (step S70). Because power supply unit 1a detects the AC voltage output from power supply unit 1b, it enters a standby state for discharge (step S72). Power supply unit 1a sends an abnormality signal indicating that an abnormality has occurred to host device 110 (step S74).

The higher-level device 110 receives the abnormality signal sent by power supply unit 1a (step S76). Upon receiving the abnormality signal, the higher-level device 110 sends an instruction to stop operation to power supply unit 1b (step S78).

Power supply unit 1b receives the instruction to stop operation sent by higher-level device 110 (step S80). Upon receiving the instruction to stop operation, power supply unit 1b stops output (step S82).

Since power supply unit 1a is stopped and no AC voltage is detected, power supply unit 1b begins discharging (step S84). Since power supply unit 1b is stopped and no AC voltage is detected, power supply unit 1a begins discharging (step S86).

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

(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.

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.

Power supply unit 1a stops outputting power due to a loss of control power (step S90). For example, power supply unit 1a loses control power due to a break in the harness connecting power supply unit 1a to the control power supply.

The processing from step S92 to step S102 is the same as the processing from step S72 to step S82 shown in Figure 6, respectively, so explanation will be omitted.

Since power supply unit 1a is stopped, no AC voltage is detected and control power has not been lost, so power supply unit 1b begins discharging using control power (step S104). Since power supply unit 1b is stopped, no AC voltage is detected and control power has been lost, so power supply unit 1a begins discharging using the power stored in the storage element (step S106).

As described above, in the second embodiment, the smoothing capacitor 20 does not discharge until the AC voltage from the other power supply device is stopped. This reduces the power consumption required to control each switch element, so even if the supply of control power from the higher-level device 110 is stopped, each switch element can ensure power to discharge the smoothing capacitor 20 after the AC voltage from the other power supply device is stopped.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the content of these embodiments. Furthermore, the components described above include those that would be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the scope of what is known as equivalents. Furthermore, the components described above can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the embodiments described above.

REFERENCE SIGNS LIST 1 power supply device 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 element 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 unit 71 photocoupler 71a light emitting unit 71b phototransistor 80 AND gate 90 control unit 91 AC voltage detection unit 92 bridge circuit control unit 93 discharge circuit control unit

Claims (6)

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. 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 . 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 . 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. 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. 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.