WO2017158916A1

WO2017158916A1 - Power supply device

Info

Publication number: WO2017158916A1
Application number: PCT/JP2016/083128
Authority: WO
Inventors: 洋平久保田; 圭一石田; 章弘石ヶ谷; 吉村　公志
Original assignee: 東芝キヤリア株式会社
Priority date: 2016-03-16
Filing date: 2016-11-08
Publication date: 2017-09-21
Also published as: JP6528002B2; JPWO2017158916A1

Abstract

The present invention detects an abnormality involving flowing of a short-circuiting current from a capacitor of a booster circuit through a first switch and a second switch of the booster circuit, in accordance with an output current of the booster circuit.

Description

Power supply

Embodiments of the present invention relate to a power supply device mounted on, for example, an air conditioner having a refrigeration cycle, a heat source machine, or the like.

A power supply device mounted on an air conditioner or a heat source apparatus having a refrigeration cycle includes a rectifier circuit that rectifies the voltage of an AC power supply, and a booster circuit that boosts the output voltage of the rectifier circuit, and the output voltage of the booster circuit Is supplied to a load such as an inverter. The inverter converts the output voltage of the booster circuit into an AC voltage having a predetermined frequency. The compressor motor in the refrigeration cycle is operated by the output of the inverter. The booster circuit includes a series circuit of a reactor and a switch (referred to as a first switch) connected to the output terminal of the rectifier circuit, a backflow prevention diode provided in a current path between the first switch and the load, It includes a capacitor connected in parallel to the first switch via a backflow prevention diode, and boosts the output voltage of the rectifier circuit by turning on and off the first switch. The load is connected in parallel to the capacitor.

When the first switch is switched from OFF to ON, a current flows through the capacitor through a path passing from the reactor through the backflow prevention diode in the forward direction. At this time, a forward voltage is generated in the backflow prevention diode. The generation of the forward voltage causes power loss of the booster circuit and cannot be ignored in terms of energy saving.

As a countermeasure, a switch having a small resistance value (referred to as a second switch) is connected in parallel to a backflow prevention diode, and this second switch is turned off when the first switch is turned on and turned on when the first switch is turned off, that is, By operating both switches in a complementary manner, forward current does not flow through the backflow prevention diode. As a result, a forward voltage is not generated in the backflow prevention diode, and thus the power loss of the booster circuit can be reduced. In this case, if both switches are turned on simultaneously, a short-circuit current flows from the capacitor through both switches. Therefore, when the first switch is switched from off to on, the second switch is turned off and the second switch is turned off. A so-called dead time is ensured when the first switch is turned off when switching on.

JP 2009-38875 A

In the above power supply apparatus, for example, when a so-called short-circuit failure occurs in the first switch while the first switch is on (closed), a short-circuit current continues to flow from the rectifier circuit through the reactor and the first switch. (Power supply short circuit error). When the power supply sag is restored, an excessive inrush current may flow through the capacitor from the rectifier circuit through the reactor and further through one of the backflow prevention diode and the second switch (abnormal current). When these abnormalities occur, the input current from the AC power supply to the power supply device becomes excessive. By capturing this overcurrent, the abnormality can be detected.

On the other hand, when an error occurs in the switching control for both switches, or when a short circuit failure occurs in the second switch that does not turn off (open) while the second switch is on (closed), both switches are turned on simultaneously. The occurrence of a situation is considered. When both switches are turned on simultaneously, a large short-circuit current flows from the capacitor through both switches. This abnormality cannot be detected from the input current from the AC power supply to the power supply device.

An object of an embodiment of the present invention is to provide a power supply device that can reliably detect an abnormality in which a short-circuit current flows from a capacitor through both switches.

The power supply device of claim 1 includes a rectifier circuit, a booster circuit, and a controller. The rectifier circuit rectifies an AC voltage. The step-up circuit includes a series circuit of a reactor and a first switch connected to the output terminal of the rectifier circuit, a backflow prevention diode provided in a current path between the first switch and a load, and the backflow prevention diode A capacitor connected in parallel to the first switch via a first switch, and a second switch connected in parallel to the backflow prevention diode. The first switch is turned on / off and the first switch is turned on / off. The output voltage of the rectifier circuit is boosted by turning on / off the second switch in phase. The controller detects an abnormality in which a short-circuit current flows from the capacitor through the first and second switches from the output current of the booster circuit.

The block diagram which shows the structure of 1st Embodiment. The figure which shows clearly the relationship between the detected electric current of each current sensor and abnormality content in 1st Embodiment, and the safety measure with respect to the abnormality. The block diagram which shows the structure of 2nd Embodiment. The figure which shows clearly the relationship between the detected electric current of each current sensor and abnormality content in 2nd Embodiment, and the safety measure with respect to the abnormality.

[1] First embodiment
Hereinafter, as a first embodiment, a power supply device mounted on an air conditioner having a refrigeration cycle will be described as an example.
As shown in FIG. 1, a full-wave rectifier circuit 2 such as a diode bridge is connected to a three-phase AC power source 1, and a booster circuit 10 is connected to the output terminal of the full-wave rectifier circuit 2. An inverter 20 that is a load of the power supply device is connected to the output terminal of the booster circuit 10. The booster circuit 10 supplies DC power to the inverter 20.

The step-up circuit 10 includes a series circuit of a reactor 11 and a switch element (first switch) SW1 connected to the output terminal of the full-wave rectifier circuit 2, and a connection point between the reactor 11 and the switch element SW1 and the inverter 20. A backflow prevention diode D2 provided in the positive current path, a capacitor (electrolytic capacitor) 12 connected in parallel to the switch element SW1 via the backflow prevention diode D2, and a switch element connected in parallel to the backflow prevention diode D2 A full-wave rectifier circuit including a second switch SW2 by turning on / off (intermittent on) of the switch element SW1 and on / off (intermittent on) of the switch element SW2 having a phase opposite to that of the switch element SW1. Function of boosting mode for boosting the output voltage (DC voltage) of 2 and switching element SW1 off (off Having the function of the non-boost operation mode to output without boosting the output voltage of the full-wave rectifying circuit 2 by connection) and on the switching element SW2 (continuation of ON). The switch element SW1 is also referred to as a lower phase side switch element, and the switch element SW2 is also referred to as an upper phase side switch element.

The switch element SW1 is a semiconductor switch element including a parasitic diode D1, for example, a MOSFET, and is turned on and off by a drive signal S1 supplied from the controller 30. The switch element SW2 includes a parasitic diode D2, has a bidirectional property in which current flows in both directions between the source and the drain when turned on, and power loss (also referred to as conduction loss) when turned on is forward of the parasitic diode D2. A semiconductor switching element such as a MOSFET, which is smaller than the power loss due to voltage, is driven on and off by a drive signal S2 supplied from the controller 30 in a phase opposite to that of the switching element SW1. The parasitic diode D2 of the switch element SW2 is used as the backflow prevention diode D2 as it is.

The inverter 20 converts the output voltage of the booster circuit 10 into an AC voltage by switching, and outputs the AC voltage as drive power to the motor 21. The motor 21 is a motor for driving the compressor 22 (for example, a brushless DC motor).

Compressor 22 sucks in refrigerant, compresses it, and discharges it. One end of the outdoor heat exchanger 24 is connected to the refrigerant discharge port of the compressor 22 via a four-way valve 23, and the other end of the outdoor heat exchanger 24 is connected to one end of the indoor heat exchanger 26 via an expansion valve 25. It is connected. The other end of the indoor heat exchanger 26 is connected to a refrigerant suction port of the compressor 22 via a four-way valve 23. The compressor 22, the four-way valve 23, the outdoor heat exchanger 24, the expansion valve 25, and the indoor heat exchanger 26 constitute a heat pump refrigeration cycle of an air conditioner. The arrows in FIG. 1 indicate the flow of the refrigerant during cooling. The high-temperature refrigerant discharged from the compressor absorbs heat by the indoor heat exchanger 26 to cool the room and radiates heat by the outdoor heat exchanger 24. That is, the indoor heat exchanger 26 becomes a heat absorber, and the outdoor heat exchanger 24 becomes a radiator. If the four-way valve 23 is reversed, the refrigerant flow is reversed and heating operation can be performed. In this case, the indoor heat exchanger 26 radiates heat to warm the room, and the outdoor heat exchanger 24 absorbs heat.

An input current detector, such as a current sensor, for detecting a current (input current to the booster circuit) Ia flowing in the reactor 11 in a current path between the positive output terminal of the full-wave rectifier circuit 2 and the reactor 11 of the booster circuit 10 13 is arranged. An output current detector, for example, a current sensor 14, that detects a current Idc flowing through the capacitor 12 and the inverter 20 is disposed in the energization path between the switch element SW 2 and the capacitor 12. A current sensor 27 that detects a current (phase winding current) that flows through the motor 22 is disposed in the energization path between the inverter 20 and the motor 21. The detection results of these

current sensors

13, 14, and 27 are supplied to the controller 30. An output voltage (voltage across the capacitor 12) Vdc of the booster circuit 10 is detected by the controller 30.

The controller 30 includes a boost control unit 40, an inverter control unit 50, a target value setting unit 51, and an abnormality detection unit 60.

The step-up control unit 40 performs pulse width modulation (PWM) switching of the step-up circuit 10 so that the output voltage Vdc of the step-up circuit 10 becomes the target value Vdcref and the input current Ia to the step-up circuit 10 is constant. The control unit includes a subtractor 41, a PI controller 42, a subtractor 43, a PI controller 44, a PWM signal generator 45, a carrier generator 46, and switch drive controllers 47 and 48.

The subtraction unit 41 obtains a deviation ΔVdc between the output voltage Vdc of the booster circuit 10 and the target value Vdcref. The PI controller 42 obtains a current command value Iref for the input current Ia to the booster circuit 10 by proportional / integral calculation using the deviation ΔVdc obtained by the subtracting unit 41 as an input. The subtracting unit 43 obtains a deviation ΔIa between the current command value Iref obtained by the PI controller 42 and the input current (detected current of the current sensor 13) Ia to the booster circuit 10. The PI controller 44 obtains a voltage command value Vref for pulse width modulation by proportional / integral calculation using the deviation ΔIa obtained by the subtractor 43 as an input. The carrier generating unit 46 generates a triangular wave carrier signal voltage Vc having a predetermined frequency. The PWM signal generation unit 45 performs pulse width modulation (voltage comparison) on the carrier command voltage Vc generated by the carrier generation unit 46 with the voltage command value Vref obtained by the PI controller 44, thereby switching the switching elements SW1, W2 of the booster circuit 10. A pulse-shaped PWM signal S0 for switching is generated.

The switch drive control unit 47 has the same phase as the PWM signal S0 generated by the PWM signal generation unit 45 when the target value Vdcref set by the target value setting unit 51 is equal to or greater than a predetermined value (during high / medium load). A drive signal S1 is generated and output for driving the switch element SW1. When the target value Vdcref set by the target value setting unit 51 is equal to or higher than a predetermined value (at the time of high / medium load), the switch drive control unit 48 has a phase opposite to that of the PWM signal S0 generated by the PWM signal generation unit 45. A drive signal S2 is generated and output for driving the switch element SW2. The booster circuit 10 operates in the boost operation mode by the outputs of the drive signals S1 and SW2.

Further, when the target value Vdcref set by the target value setting unit 51 is less than a predetermined value (when the load is low), the switch drive control unit 47 generates a drive signal S1 for continuously turning off the switch element SW1. Output. When the target value Vdcref set by the target value setting unit 51 is less than a predetermined value (when the load is low), the switch drive control unit 48 generates and outputs a drive signal S2 for continuously turning on the switch element SW2. . Since the switch element SW1 is continuously turned off by the outputs of the drive signals S1 and SW2, the booster circuit 10 enters the non-boosting operation mode.

The target value Vdcref is set according to the load of the heat pump refrigeration cycle (so-called refrigeration load), and is set to a low value during a low refrigeration load when the compressor 22 (motor 21) is in a low rotation state. The compressor 22 is set to a high value during a high refrigeration load when the engine 22 is in a high rotation state. When the target value Vdcref is low and the refrigeration load is low, the booster circuit 10 operates in the non-boosting operation mode.

In particular, the switch drive control units 47 and 48 are arranged so that the switch element SW2 is switched from on to off before the switch element SW1 is switched from off to on, that is, the timing and switch when the switch element SW1 is switched from off to on. The switch after the switch element SW1 is switched from on to off so as to ensure a dead time during which both the switch elements SW1 and SW2 are turned off between the timing when the element SW2 is switched from on to off. Both the switch elements SW1 and SW2 are in an off state so that the element SW2 is switched from off to on, that is, between the timing when the switch element SW1 is switched from on to off and the timing when the switch element SW2 is switched from on to off. Drive signals S1 and S2 are generated so as to ensure a dead time of .

The subtraction unit 41 and the PI controller 42 function as a voltage control system. The subtractor 43 and the PI controller 44 function as a current control system. With this voltage control system and current control system, switching of the booster circuit 10 is PWM controlled so that the output voltage Vdc of the booster circuit 4 becomes the target value Vdcref and the input current I to the booster circuit 4 is constant. Is done.

The inverter control unit 50 estimates the speed (rotational speed) of the brushless DC motor 21 from the detected current (motor current) of the current sensor 27, and inverts the estimated speed to a target speed corresponding to the size of the refrigeration load. 20 switching is PWM controlled. The target value setting unit 51 sets the minimum output voltage Vdc of the booster circuit 10 necessary for the output voltage of the inverter 20 to obtain the target speed as the target value Vdcref.

The abnormality detection unit 60 detects an abnormality in which the short-circuit current A continues to flow from the full-wave rectifier circuit 2 through the switch element SW1 based on the detection current Ia of the current sensor 13 as well as the full-wave. An abnormality (referred to as an overcurrent abnormality) in which an excessive current such as an inrush current flows through the capacitor 12 in a path from the rectifier circuit 2 through the reactor 11 and further through one of the backflow prevention diode D2 and the switch element SW2. Detection is based on 13 detection currents Ia. Specifically, the abnormality detection unit 60 determines that either “power supply short circuit abnormality” or “overcurrent abnormality” has occurred when the detection current Ia of the current sensor 13 has risen above the threshold value Ias.

In addition, the abnormality detection unit 60 detects an abnormality in which a large short-circuit current B (= −Idc) flows in a path from the capacitor 12 through the switch elements SW1 and SW2 (referred to as an upper / lower short-circuit abnormality) based on the detection current Idc of the current sensor 14. To detect. Specifically, the abnormality detection unit 60 determines that an “upper and lower short circuit abnormality” has occurred when the detected current Idc of the current sensor 14 increases in the negative direction and reaches a threshold value −Idcs or more.

The detection result (determination result) of the abnormality detection unit 60 is supplied to the switch drive control units 47 and 48 and the inverter control unit 50.

The switch drive control units 47 and 48 forcibly switch the switch elements SW1 and SW2 for safety protection when either the “power supply short circuit abnormality” or the “overcurrent abnormality” is detected by the abnormality detection unit 60. Turn off. Further, the switch drive control units 47 and 48 forcibly turn off the switch elements SW1 and SW2 for safety protection when the “abnormality of vertical short circuit” is detected by the abnormality detection unit 60.

Inverter control unit 50 detects that either “power supply short-circuit abnormality” or “overcurrent abnormality” is detected by abnormality detection unit 60 and the detection of the abnormality is not temporary but continues for a predetermined time. 20 switching is stopped (that is, the refrigeration load is stopped). Further, when “abnormality of upper and lower short circuit” is detected by the abnormality detection unit 60, the inverter control unit 50 immediately stops switching of the inverter 20 (that is, stops the refrigeration load).

At least the full-wave rectifier circuit 2, the booster circuit 10, the

current sensors

13 and 14, and the controller 30 constitute a power supply device according to this embodiment.

Next, the control executed by the controller 30 will be described. The relationship between the detected currents Ia and Idc of the

current sensors

13 and 14 and the content of the abnormality and the safety measures for the abnormality are shown in FIG.

When the motor 21 rotates at high and medium speeds, the switch element SW1 is turned on and off, and the switch element SW2 is turned on and off in a phase opposite to that of the switch element SW1. As a result, the output voltage of the full-wave rectifier circuit 2 is boosted by the booster circuit 10 and supplied to the inverter 20. When the motor 21 rotates at a low speed and the load is low, the switch element SW1 is continuously turned off and the switch element SW2 is continuously turned on. As a result, the output voltage of the full-wave rectifier circuit 2 passes through the reactor 11 and the switch element SW2, and is supplied to the inverter 20 via the capacitor 12 without being boosted.

By the way, when a short-circuit failure that does not turn off (open) while the switch element SW1 is on (closed) occurs, a “short circuit of power supply” occurs in which the short-circuit current A continues to flow from the full-wave rectifier circuit 2 through the switch element SW1. It can happen. Further, there is a possibility that an “overcurrent abnormality” in which an overcurrent such as an inrush current flows through the capacitor 12 through a path from the full-wave rectifier circuit 2 to the switch element SW2. When either of such “abnormality of power supply short-circuit” and “abnormality of overcurrent” occurs, the detection current Ia of the current sensor 13 rises to the threshold value Ias or more. When the detection current Ia of the current sensor 13 rises above the threshold value Ias, the abnormality detection unit 60 determines that “power supply short circuit abnormality” or “overcurrent abnormality” has occurred. In this determination, the switch drive control unit 47 forcibly turns off the switch element SW1, and the switch drive control unit 48 forcibly turns off the switch element SW2. Thereby, destruction of the electrical components of the booster circuit 10 and the full-wave rectifier circuit 2 due to the short circuit current A and the overcurrent can be prevented.

When an “overcurrent abnormality” occurs, if the switch element SW2 is in an off state, the overcurrent flows through the backflow prevention diode D2, but the backflow prevention diode D2 is sufficient for the overcurrent. Therefore, the backflow prevention diode D2 will not be destroyed.

In addition, a large short-circuit current B flows from one end of the capacitor 12 to the other end due to a switching control error with respect to the switch elements SW1 and SW2 or a short-circuit failure of the switch element SW2. An “abnormality” may occur. When this “upper and lower short circuit abnormality” occurs, the detection current Idc of the current sensor 14 increases in the negative direction and becomes equal to or greater than the threshold −Idcs. When the detection current Idc of the current sensor 14 increases in the negative direction and reaches the threshold value −Idcs or more, the abnormality detection unit 60 determines that “upper and lower short circuit abnormality” has occurred. In this determination, the switch drive control units 47 and 48 forcibly turn off the switch elements SW1 and SW2. Thereby, destruction of the electrical components of the booster circuit 10 and the full-wave rectifier circuit 2 due to the short-circuit current B can be prevented.

As described above, the “current supply short-circuit abnormality”, “overcurrent abnormality”, and “upper and lower short-circuit abnormality” in the booster circuit 10 can be reliably detected by the two

current sensors

13 and 14. When the abnormality is detected, the switch elements SW1 and SW2 are forcibly turned off, so that the booster circuit 10 and the full-wave rectifier circuit 2 can be protected. Since the current sensor 13 is originally prepared for current control of the boost control unit 40, it is not necessary to prepare a new current sensor for detecting an abnormality. Therefore, an increase in cost can be suppressed.

[2] Second embodiment
A second embodiment will be described.
As shown in FIG. 3, the booster circuit 10 includes a series circuit of a reactor 11 and a switch element (first switch) SW1 connected to the output terminal of the full-wave rectifier circuit 2, and an interconnection point between the reactor 11 and the switch element SW1. Is connected in parallel to the backflow prevention diode 15, the capacitor 12 connected in parallel to the switch element SW 1 via the backflow prevention diode 15, and the backflow prevention diode 15. The switch elements SW2 and SW3 are connected in series (second switch). The switch elements SW1 and SW3 are turned on and off (intermittently on) and the switch elements SW1 and SW3 are turned on and off. Function of boosting operation mode for boosting the output voltage of full-wave rectifier circuit 2 by turning off (intermittently on), and switching element SW Having off (continuation of OFF) and the switch elements SW2, SW3 turned on by (continuation of ON) of the non-boost operation mode to output without boosting the output voltage of the full-wave rectifier circuit 2 function. That is, instead of the switch element SW2 of the first embodiment, a series circuit of a switch element (front stage switch) SW2 and a switch element (back stage switch) SW3 is employed.

The switch elements SW2 and SW3 operate in synchronization with each other by receiving the same drive signal S2. While the booster circuit 10 is operating normally, almost no current flows through the backflow prevention diode 15, so that a low-cost, small capacity (rated) component can be used as the backflow prevention diode 15. In other words, the backflow prevention diode 15 has a capacity capable of continuously flowing a current having the same magnitude as the current (boosted current) flowing in the series circuit of the switch elements SW2 and SW3 when the load is large. do not do.

The switch element SW1 is the same as that of the first embodiment, and is turned on and off by the drive signal S1 supplied from the controller 30. The switch element SW2 includes a parasitic diode D2 and is a low breakdown voltage MOSFET having a bidirectional property in which a current flows in both directions between the source and the drain when the switch element SW2 is turned on. It is turned on and off in the opposite phase to on and off. A low withstand voltage MOSFET inherently has a low on-resistance and thus has a low loss, thus preventing a reduction in efficiency. The switch element SW3 is a semiconductor switch element, for example, a super junction MOSFET, and is turned on / off by a drive signal S2 supplied from the controller 30 in a phase opposite to the on / off state of the switch element SW1. That is, the switch elements SW2 and SW3 are driven in synchronization with each other.

The series circuit of the switch elements SW2 and SW3 is formed by connecting the switch elements SW2 and SW3 in series in opposite directions (series connected in opposite polarities), and suppresses the reverse recovery current of the parasitic diode D3 of the switch element SW3. A high-efficiency switching circuit is formed together with the backflow prevention diode 15. Thereby, higher efficiency than the first embodiment can be obtained. The power loss (also referred to as conduction loss) due to the resistance value of the series circuit (the total resistance value of the switch elements SW2 and SW3) when the switch elements SW2 and SW3 are turned on is the power due to the forward voltage of the backflow prevention diode 15 Less than loss. The high-efficiency switching circuit corresponds to, for example, a semiconductor switch circuit described in Japanese Patent Application Laid-Open No. 2015-156795, and effectively uses a reverse recovery current of a parasitic diode (also referred to as a free wheel diode) D3 of the switch element SW3. By suppressing, the loss is reduced and the switching speed is increased. A detailed description of the semiconductor switch circuit is omitted.

The current sensor 14 is disposed at a position upstream of the connection point of the backflow prevention diode 15 in the current path between the series circuit of the switch elements SW2 and SW3 and the capacitor 12, and the current sensor 14 is connected to the switch elements SW2 and SW3. A current Idc flowing through the capacitor 12 and the inverter (load) 20 through the series circuit is detected.

The anomaly detection unit 60 is configured so that the short-circuit current A continues to flow in the path passing through the switch element SW1 from the positive side terminal to the negative side terminal of the full-wave rectifier circuit 2, and from the full-wave rectifier circuit 2 to the reactor 11 In the same way as in the first embodiment, an “overcurrent abnormality” is caused by excessive current such as an inrush current flowing through the capacitor 12 in the path passing through the backflow prevention diode 15 or the on-state switch elements SW2 and SW3. Detection is performed according to the detection current Ia of the sensor 13. Further, the abnormality detection unit 60 performs the “upper and lower short circuit abnormality” in which a large short-circuit current B (= −Idc) flows through the switch elements SW3, SW2, and SW1 from one end to the other end of the capacitor 12 in the first implementation. The detection is performed according to the detection current Idc of the current sensor 14 as in the embodiment.

Furthermore, the abnormality detection unit 60 detects an abnormality that does not turn on (close) while one of the switch elements SW2 and SW3 is off (open), that is, an “open failure abnormality”. The “open failure abnormality” of the switch element SW2 includes an abnormality in which the parasitic diode D2 does not conduct. The “open failure abnormality” of the switch element SW3 includes an abnormality in which the parasitic diode D3 does not conduct. These “open failure abnormalities” can be detected by the difference ΔI (= Ia−Idc) between the detection current Ia of the current sensor 13 and the detection current Idc of the current sensor 14. Specifically, when an “open fault abnormality” occurs in either of the switch elements SW2 and SW3, the detection current Idc of the current sensor 14 becomes zero, so the difference ΔI (= Ia−Idc) is larger than the threshold value α. Become. When the difference ΔI becomes larger than the threshold value α, the abnormality detection unit 60 determines that an “open failure abnormality” has occurred in one of the switch elements SW2 and SW3. In this case, the current Ia detected by the current sensor 13 flows through the backflow prevention diode 15 in the forward direction to the capacitor 12 side.

The detection result of the abnormality detection unit 60 is supplied to the switch drive control units 47 and 48 and the inverter control unit 50.

The switch drive control unit 47 forcibly switches the switch element SW1 in the same manner as in the first embodiment when either the “power supply short circuit abnormality” or the “overcurrent abnormality” is detected by the abnormality detection unit 60. Turn off. The switch drive control unit 48 forcibly turns on the switch elements SW2 and SW3 when either the “power supply short circuit abnormality” or the “overcurrent abnormality” is detected by the abnormality detection unit 60.

The switch drive control unit 47 forcibly turns off the switch element SW1 for safety protection, as in the first embodiment, when “abnormality of vertical short circuit” is detected by the abnormality detection unit 60. The switch drive control unit 48 forcibly turns off the switch elements SW2 and SW3 for safety protection when the “abnormality of vertical short circuit” is detected by the abnormality detection unit 60.

Further, the switch drive control unit 47 forcibly turns off the switch element SW1 when any one of the switch elements SW2 and SW3 detects “open failure” in the abnormality detection unit 60. The switch drive control unit 48 forcibly turns off the switch elements SW2 and SW3 when any one of the switch elements SW2 and SW3 detects “abnormal open fault” by the abnormality detection unit 60. However, in the case of “abnormality of open failure”, even if an OFF signal is input to the switch elements SW2 and SW3, the operation state does not change, so that a large current flows through the backflow prevention diode 15 having a small capacity. Can not. Therefore, the inverter control unit 50 immediately stops the switching of the inverter 20 and detects the backflow prevention diode 15 when the “abnormality of open failure” of either of the switch elements SW2 and SW3 is detected by the abnormality detection unit 60. Prevent destruction.

The inverter control unit 50 performs the same control as that in the first embodiment when any one of “abnormality of power supply short-circuit”, “abnormality of overcurrent”, and “abnormality of vertical short-circuit” is detected by the abnormality detection unit 60. Do.

Other configurations are the same as those in the first embodiment. The description of the same part is omitted.

Next, of the control executed by the controller 30, the control when either “power supply short circuit abnormality” or “overcurrent abnormality” occurs and the control when “open failure abnormality” occurs will be described. To do. The relationship between the detected currents Ia and Idc of the

current sensors

When either the “power supply short circuit abnormality” or the “overcurrent abnormality” is detected by the abnormality detection unit 60, the switch drive control unit 47 forcibly turns off the switch element SW1, and the switch drive control unit 48 The elements SW2 and SW3 are forcibly turned on. When the “overcurrent abnormality” occurs, if the switch elements SW2 and SW3 remain off, all of the overcurrent flows through the backflow prevention diode 15 having a small capacity, and the backflow prevention diode 15 is destroyed. There is a possibility. In order to prevent this destruction, the switch elements SW2 and SW3 are forcibly turned on.

When an “open fault abnormality” occurs in which one of the switch elements SW2 and SW3, for example, the switch element SW3 is turned off and does not turn on, the current Idc flowing from the series circuit of the switch elements SW2 and SW3 to the capacitor 12 becomes zero or zero. Decrease to a close value. At this time, since the difference ΔI (= Ia−Idc) between the detection current Ia of the current sensor 13 and the detection current Idc of the current sensor 14 becomes larger than the threshold value α, the abnormality detection unit 60 can detect either of the switch elements SW2 and SW3. It is determined that an “open failure abnormality” has occurred. In this determination, the switch drive control unit 47 forcibly turns off the switch element SW1, the switch drive control unit 48 forcibly turns off the switch elements SW2 and SW3, and the inverter control unit 50 switches the inverter 20 that is a load. Stop immediately.

As described above, the “current supply short-circuit abnormality”, “overcurrent abnormality”, “upper and lower short-circuit abnormality”, and “open failure abnormality” in the booster circuit 10 can be reliably detected by the

current sensors

13 and 14. In addition, since the operations of the switch elements SW1, SW2, SW3 and the inverter 20 are appropriately controlled to the safe side according to the detected abnormality, the booster circuit 10 and the full-wave rectifier circuit 2 can be protected.

The above embodiments are presented as examples, and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, rewrites, and changes can be made without departing from the scope of the invention. In these embodiments, the scope of the invention is included in the gist, and is included in the invention described in the claims and an equivalent scope thereof.

The power supply apparatus according to the embodiment of the present invention can be mounted on an air conditioner or a heat source apparatus having a refrigeration cycle.

Claims

A rectifier circuit for rectifying an alternating voltage;
A series circuit of a reactor and a first switch connected to the output terminal of the rectifier circuit, a backflow prevention diode provided in a current path between the first switch and a load, and the backflow prevention diode via the backflow prevention diode A capacitor connected in parallel to one switch and a second switch connected in parallel to the backflow prevention diode, wherein the first switch is turned on and off and the first switch is turned on and off in phase opposite to the second A booster circuit that boosts the output voltage of the rectifier circuit by turning on and off the switch;
A controller for detecting an abnormality in which a short-circuit current flows from the capacitor through the first switch and the second switch based on an output current of the booster circuit;
A power supply apparatus comprising:
The controller turns off the first switch and the second switch when the abnormality is detected;
The power supply device according to claim 1.
The controller immediately stops the load when detecting the abnormality.
The power supply device according to claim 1, wherein the power supply device is provided.
The second switch includes a parasitic diode, has a bidirectional property in which a current flows in both directions when turned on, and is a semiconductor switch element in which the power loss when turned on is smaller than the power loss due to the forward current of the parasitic diode. is there,
The backflow prevention diode is the parasitic diode of the second switch.
The power supply device according to any one of claims 1 to 3, wherein the power supply device is provided.
The controller is
Detecting an abnormality in which a short-circuit current continues to flow from the rectifier circuit through the reactor and the first switch based on an input current to the rectifier circuit;
Detecting an abnormality in which an overcurrent flows from the rectifier circuit to the capacitor through the second switch based on an input current to the rectifier circuit;
The power supply device according to claim 1.
The second switch is a series circuit of a front switch and a rear switch,
An input current detector for detecting an input current to the booster circuit;
An output current detector for detecting a current flowing through the capacitor and the load through a series circuit of the front-stage switch and the rear-stage switch;
Further comprising
The controller detects an abnormality in which a short-circuit current flows from the capacitor through the first switch and the second switch from a detection result of an output current detector, and turns on while either the front switch or the rear switch is off. Detecting a failure that does not occur according to the detection result of the input current detector and the detection result of the output current detector,
The power supply device according to claim 1.
The pre-stage switch is a semiconductor switch element including a parasitic diode and having bidirectionality in which current flows bidirectionally when turned on.
The post-stage switch is a semiconductor switch element including a parasitic diode and having bidirectionality in which current flows bidirectionally when turned on.
The series circuit of the front-stage switch and the rear-stage switch includes a high-efficiency switching circuit for preventing the reverse current by connecting the front-stage switch and the rear-stage switch in series in opposite directions and suppressing a reverse recovery current of a parasitic diode of the rear-stage switch. It is formed together with a diode, and the power loss when the front-stage switch and the rear-stage switch are turned on is smaller than the power loss due to the forward current of the backflow prevention diode,
The power supply device according to claim 6.
The backflow prevention diode does not have a capacity capable of continuously flowing a current having the same magnitude as the current flowing in the series circuit of the front-stage switch and the rear-stage switch when the load is large.
The power supply device according to claim 7.
The controller is
When a failure is detected that does not turn on while either the front switch or the rear switch is off, the first switch is turned off and the front switch and the rear switch are turned off.
The power supply device according to any one of claims 6 to 8, wherein
The controller is
When a failure is detected that does not turn on while either the front switch or the rear switch is off, the load is immediately stopped.
The power supply device according to any one of claims 6 to 9, wherein