JP2015070644A - Ac-dc converter and compressor drive device, and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an AC-DC converter and a compressor drive device capable of preventing application of a reverse voltage to a capacitor, which is caused by failure of a switching element, and of facilitating to find out cause of the failure, and further to provide an air conditioner.SOLUTION: An AC-DC converter comprises: first and second rectifiers 3 and 4 connected in parallel to an AC power supply 1 via a reactor 2; two capacitors 7 and 8 connected in series between output terminals to a DC load 22 of the first rectifier 3; two switching elements 5 and 6 connected in series between output terminals of the second rectifier 4, and whose connection point is connected to a connection point of the two capacitors 7 and 8; and a controller 15 performing failure determination of the two switching elements 5 and 6 on the basis of each voltage across each of the two capacitors 7 and 8 when boosting control is performed, and it is determined that one of the two switching elements 5 and 6 is failed, controlling the two switching elements 5 and 6 to be OFF to stop the boosting control, and stopping the DC load 22.

Description

  The present invention relates to an AC / DC converter, a compressor driving device, and an air conditioner.

  Conventionally, first and second rectifiers connected in parallel to an AC power source via a reactor, a plurality of capacitors connected in series between output terminals of the first rectifier, and a positive side of the second rectifier Switching element inserted between the connection point of the plurality of capacitors and the second switching element inserted between the negative electrode side of the second rectifier and the connection points of the plurality of capacitors A first voltage detector for detecting voltages across the plurality of capacitors, a second voltage detecting means for detecting a voltage of a capacitor located on a low potential side of the plurality of capacitors, and the plurality of the plurality of capacitors. The third voltage detecting means for detecting the voltage of the capacitor located on the high potential side of the capacitors and the first and second switching elements are operated during a half cycle of the AC power supply to obtain a desired output voltage. And a control unit that controls the first and second switching elements so that a difference between the detection voltages of the second and third voltage detection means is reduced. An apparatus has been proposed (for example, Patent Document 1).

JP 2009-261077 A

  As a capacitor on the high potential side and the low potential side constituting the AC / DC converter, generally a large-capacity polar electrolytic capacitor is used. According to the above prior art, when the first and second switching elements are operating normally, the capacitor voltage is unbalanced due to switching variations, capacitor capacitance variations, etc., that is, the second and second switching elements. It is possible to perform control so that the difference between the detection voltages of the voltage detection means 3 is reduced (hereinafter referred to as “voltage balance correction control”), but the first or second switching element is short-circuited or opened. In the case of failure, the voltage balance correction control described above does not work normally. For this reason, when the subsequent DC load is continuously operated, a voltage opposite to the normal voltage is applied to the high-potential side or low-potential side capacitor, which may cause secondary destruction of the capacitor. When a secondary failure occurs, it becomes difficult to investigate the cause of the failure. In addition, it is conceivable to use a nonpolar bipolar capacitor in order to prevent the destruction of the capacitor due to the application of the reverse voltage. However, since a large-capacity electrolytic capacitor is generally expensive, it causes a high cost of the apparatus. There was a problem of becoming.

  The present invention has been made in view of the above, and it is possible to prevent application of a reverse voltage to a capacitor due to a failure of a switching element, and to easily investigate the cause of the failure. The purpose is to provide a harmony machine.

  In order to solve the above-described problems and achieve the object, an AC / DC converter according to the present invention is an AC / DC converter that converts AC power supplied from an AC power source into DC power and supplies it to a DC load. The first and second rectifiers connected in parallel to the AC power source via a reactor, the two capacitors connected in series between the output terminals of the first rectifier to the DC load, and the second Two switching elements connected in series between the output terminals of the rectifier, the connection point of which is connected to the connection point of the two capacitors, and the output voltage value to the DC load by controlling the two switching elements A control unit that controls the DC load, and the control unit is configured to control the two loads based on voltages across the two capacitors during the boost control. When a failure determination of the switching element is performed and it is determined that one of the two switching elements has failed, the step-up control is stopped by turning off the two switching elements, and the DC load is It is characterized by being stopped.

  According to the present invention, it is possible to prevent reverse voltage application to the capacitor due to the failure of the switching element, so it can be configured at low cost without using an expensive bipolar electrolytic capacitor, and the cause of the failure can be easily investigated. There is an effect.

FIG. 1 is a diagram of a configuration example of the AC / DC converter according to the first embodiment. FIG. 2 is a diagram of a configuration example of an overcurrent protection circuit in the AC / DC converter according to the first embodiment. FIG. 3 is a diagram illustrating an operation example when both the first and second switching elements are on. FIG. 4 is a diagram illustrating an operation example when the first switching element is on and the second switching element is off. FIG. 5 is a diagram illustrating an operation example when the first switching element is off and the second switching element is on. FIG. 6 is a diagram illustrating an operation example when both the first and second switching elements are off. FIG. 7 is a diagram illustrating an operation example of the power supply zero-cross detection circuit. FIG. 8 is a diagram showing the relationship between the power supply voltage Vs and the converter voltage Vc when the power supply power factor of the AC power supply 1 is 100%. FIG. 9 is a diagram illustrating an example of the drive signals Sa and Sb near the converter voltage peak when the target DC voltage Vdc * is low. FIG. 10 is a diagram illustrating an example of the drive signals Sa and Sb in the vicinity of the converter voltage peak when the target DC voltage Vdc * is high. FIG. 11 is a diagram illustrating a voltage unbalanced state of the first and second capacitors. FIG. 12 is an operation flowchart based on the determination result of the failure determination unit in the AC / DC converter according to the first embodiment. FIG. 13 is a diagram of a configuration example of the AC / DC converter according to the second embodiment. FIG. 14 is a diagram illustrating a configuration example of an inverter main circuit. FIG. 15 is an operation flowchart based on the determination result of the failure determination unit in the AC / DC converter according to the second embodiment. FIG. 16 is a diagram of a configuration example of the AC / DC control device according to the third embodiment. FIG. 17 is a diagram of a configuration example of an overcurrent protection circuit in the AC / DC converter according to the third embodiment. FIG. 18 is an operation flowchart of the failure determination unit in the AC / DC converter according to the third embodiment. FIG. 19 is an operation flowchart based on the determination result of the failure determination unit in the AC / DC converter according to the third embodiment. FIG. 20 is an operation flowchart different from FIG. 19 based on the determination result of the failure determination unit in the AC / DC converter according to the third embodiment. FIG. 21 is a diagram of a configuration example of the AC / DC converter according to the fourth embodiment. FIG. 22 is an operation flowchart of the failure determination unit in the AC / DC converter according to the fourth embodiment. FIG. 23 is an operation flowchart different from FIG. 22 of the failure determination means in the AC / DC converter according to the fourth embodiment.

  Hereinafter, an AC / DC converter, a compressor driving device, and an air conditioner according to an embodiment of the present invention will be described with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

Embodiment 1 FIG.
FIG. 1 is a diagram of a configuration example of the AC / DC converter according to the first embodiment. In the example illustrated in FIG. 1, the AC / DC converter 100 according to the first embodiment has a configuration in which AC power supplied from the AC power supply 1 is converted into DC power and supplied to the DC load 22. As the DC load 22, for example, an inverter that converts a DC power supplied from the AC / DC converter 100 into an AC power and drives a motor (not shown) is assumed.

  As shown in FIG. 1, the AC / DC converter according to the first embodiment includes a first rectifier 3 and a second rectifier 4 connected in parallel to an AC power supply 1 via a reactor 2, and a DC load of the rectifier 3. The first capacitor 7 (high potential side) and the second capacitor 8 (low potential side) connected in series between the output terminals to 22 and the output terminal of the rectifier 4 are connected in series. A first switching element 5 and a second switching element 6 connected to a connection point of one capacitor 7 and a second capacitor 8, a reverse voltage prevention diode 9 connected in reverse parallel to the first capacitor 7, A reverse voltage prevention diode 10 connected in reverse parallel to the second capacitor 8, a first voltage detection circuit 11 that detects a voltage Vc 2 across the second capacitor 8, and a voltage between the output terminals of the rectifier 3 (hereinafter, simply" A second voltage detection circuit 12 that detects Vdc, a power supply zero-cross detection circuit 13 that detects a voltage zero cross of the AC power supply 1, and a current (hereinafter simply referred to as “power supply current”) Is of the AC power supply 1. And a control for controlling the first and second switching elements 5 and 6 so that the DC voltage Vdc has a desired output voltage value (synonymous with “target DC voltage Vdc *” described later). 15, a drive circuit 16 that converts the drive signal Sa of the first switching element 5 output from the control unit 15 into a voltage that can drive the first switching element 5, and a second output from the control unit 15. A driving circuit 17 that converts the driving signal Sb of the switching element 6 into a voltage that can drive the second switching element 6, and an electric current that detects the current flowing through the first switching element 5. Based on the output value from the detection part 18, the current detection part 19 which detects the electric current which flows into the 2nd switching element 6, and the current detection parts 18 and 19, the overcurrent of the 1st and 2nd switching elements 5 and 6 An overcurrent protection circuit 20 that performs a protection operation and a failure notification unit 21 that notifies of a failure of the first and second switching elements 5 and 6 are provided. In the following description, it is assumed that the effective voltage of the AC power supply 1 is 200V.

  The rectifier 3 is configured by full-bridge connection of diodes 3a to 3d. More specifically, the anode of the diode 3a and the cathode of the diode 3b are connected, the anode of the diode 3c and the cathode of the diode 3d are connected, the cathodes of the diode 3a and the diode 3c are connected together, and the diode 3b and the diode 3d anodes are connected to each other. The connection point between the anode of the diode 3a and the cathode of the diode 3b is connected to one end of the AC power supply 1 through the reactor 2, and the connection point between the anode of the diode 3c and the cathode of the diode 3d is connected to the current detection unit 14. To the other end of the AC power source 1.

  The rectifier 4 is configured by full-bridge connection of diodes 4a to 4d. More specifically, the anode of the diode 4a and the cathode of the diode 4b are connected, the anode of the diode 4c and the cathode of the diode 4d are connected, the cathodes of the diode 4a and the diode 4c are connected, and the diode 4b and the diode 4d anodes are connected to each other. The connection point between the anode of the diode 4a and the cathode of the diode 4b is connected to one end of the AC power source 1 through the reactor 2, and the connection point between the anode of the diode 4c and the cathode of the diode 4d is connected to the current detection unit 14. To the other end of the AC power source 1.

  The first voltage detection circuit 11 includes a resistor 11a, a resistor 11b, and a resistor 11c connected in series from the high potential side between the output terminals of the rectifier 3. The connection point between the resistor 11 a and the resistor 11 b is connected to the connection point between the first switching element 5 and the second switching element 6 and the connection point between the first capacitor 7 and the second capacitor 8. . The resistance value of the resistor 11a and the combined resistance value of the resistor 11b and the resistor 11c are substantially matched, and the voltage Vc1 across the first capacitor 7 and the voltage Vc2 across the second capacitor 8 are in an equilibrium state. The balance resistance is also used to maintain the balance. A connection point between the resistor 11b and the resistor 11c is connected to an A / D converter 15a included in the control unit 15, and the control unit 15 determines a second capacitor based on a voltage value at a connection point between the resistor 11b and the resistor 11c. 8 to obtain a voltage Vc2 between both ends. In the example shown in FIG. 1, the example in which the first voltage detection circuit 11 is configured by three resistors 11a, 11b, and 11c is shown. For example, two resistors having the same resistance value as the resistors 11b and 11c are shown. May be connected in series to form the resistor 11a, may be configured differently from the above-described balance resistor, and is a known one that can detect the voltage Vc2 across the second capacitor 8. The configuration of the first voltage detection circuit 11 is not limited by the configuration of the first voltage detection circuit 11.

  The second voltage detection circuit 12 includes a resistor 12a and a resistor 12b connected in series from the high potential side between the output terminals of the rectifier 3. A connection point between the resistor 12a and the resistor 12b is connected to an A / D converter 15b included in the control unit 15, and the control unit 15 obtains a DC voltage Vdc from a voltage value at a connection point between the resistor 12a and the resistor 12b. The structure is to get. The example shown in FIG. 1 shows an example in which the second voltage detection circuit 12 is configured by two resistors 12a and 12b, but any known configuration capable of detecting the DC voltage Vdc may be used. The present invention is not limited by the configuration of the second voltage detection circuit 12.

  The control unit 15 includes an A / D converter 15a that performs A / D conversion on the output voltage value of the first voltage detection circuit 11, and an A / D conversion that performs A / D conversion on the output voltage value of the second voltage detection circuit 12. 15b, an A / D converter 15c for A / D converting the output value of the current detector 14, and a failure determination means 15d. The control unit 15 can be realized by a microcomputer, for example.

  Here, in the present embodiment, as shown in FIG. 1, the reference ground of the control unit 15 is shared (non-insulated) with the negative potential of the DC voltage Vdc. The voltage Vc2 between both ends of the second capacitor 8 and the DC voltage are obtained by inputting the output voltage values of the two voltage detection circuits 12 to the A / D converter 15a and the A / D converter 15b, respectively, and performing A / D conversion. Vdc can be obtained. In the example shown in FIG. 1, the connection point between the resistor 11b and the resistor 11c and the A / D converter 15a are directly connected, and the connection point between the resistor 12a and the resistor 12b and the A / D converter 15b are directly connected. Although it is set as the structure connected, between the connection point of the resistor 11b and the resistor 11c and the A / D converter 15a, and between the connection point of the resistor 12a and the resistor 12b and the A / D converter 15b, Needless to say, the effect of erroneous voltage detection due to noise can be reduced by inserting a low-pass filter composed of a resistor and a capacitor. However, in the example shown in FIG. 1, the low-pass filter is not shown.

  The control unit 15 also has a function of controlling the DC load 22 in addition to the function of controlling the first and second switching elements 5 and 6.

  Each current detection part 14, 18, and 19 is realizable using a current transformer, for example. The output of the current detection unit 14 is connected to an A / D converter 15c provided in the control unit 15, and the control unit 15 is configured to obtain the power supply current Is from the output value of the current detection unit 14. The output value Isw1_level of the current detection unit 18 and the output value Isw2_level of the current detection unit 19 are input to the overcurrent protection circuit 20, and at least one of these two output values Isw1_level and Isw2_level is equal to or higher than an overcurrent protection level OC_LEVEL described later. At this time, the drive signals Sa and Sb of the first and second switching elements 5 and 6 output from the control unit 15 to the drive circuits 16 and 17 are forcibly turned off.

  In the present embodiment, as shown in the drawing, polar electrolytic capacitors are used as the first and second capacitors 7 and 8. In general, a polar electrolytic capacitor has a resistance to a reverse voltage as small as about 1V. Therefore, in the present embodiment, reverse voltage prevention diodes 9 and 10 are connected in reverse parallel to the first and second capacitors 7 and 8, respectively, and the reverse voltage is applied to the first and second capacitors 7 and 8. Is preventing. In the present embodiment, the purpose is to prevent reverse voltage from being applied to the first and second capacitors 7 and 8 when the DC load 22 is stopped. As the diodes 9 and 10, diodes having a small current capacity (for example, about 1 A) may be selected.

  In the example shown in FIG. 1, an example in which an IGBT (Insulated Gate Bipolar Transistor) is used as the first and second switching elements 5 and 6 is shown, but other switching elements (for example, MOSFETs) are used. The present invention is not limited by the configuration of the first and second switching elements 5 and 6.

  The failure notification means 21 is constituted by, for example, an LED. When the failure determination unit 15d provided in the control unit 15 determines that the first switching element 5 or the second switching element 6 has a short circuit failure or an open failure, the control unit 15 may include, for example, a failure notification unit. The failure is notified by blinking the LED which is 21. In the normal time when the first and second switching elements 5 and 6 are normal, the control unit 15 makes the switching elements 5 and 6 normal by, for example, lighting an LED that is the failure notification means 21. Is notified.

  Next, the configuration of the overcurrent protection circuit 20 will be described with reference to FIG. FIG. 2 is a diagram of a configuration example of an overcurrent protection circuit in the AC / DC converter according to the first embodiment.

  In the example shown in FIG. 2, the overcurrent protection circuit 20 includes a comparator 20a, a comparator 20b, an AND circuit 20c, a latch circuit 20d, an AND circuit 20e, and an AND circuit 20f.

  The comparator 20a compares the output value Isw1_level of the current detection unit 18 with a predefined overcurrent protection level OC_LEVEL, and outputs a Lo level when Isw1_level ≧ OC_LEVEL, and a Hi level when Isw1_level <OC_LEVEL. Is output. Similarly, the comparator 20b compares the output value Isw2_level of the current detection unit 19 with the overcurrent protection level OC_LEVEL, outputs the Lo level when Isw2_level ≧ OC_LEVEL, and the Hi level when Isw2_level <OC_LEVEL. Is output.

  The AND circuit 20c outputs a logical product of the output of the comparator 20a and the output of the comparator 20b. That is, when either one of the output of the comparator 20a and the output of the comparator 20b is at the Lo level, the Lo level is output, and when both are at the Hi level, the Hi level is output.

  The latch circuit 20d normally outputs the Hi level, and latches (holds) its own output at the Lo level when the output of the AND circuit 20c becomes Lo. The output of the latch circuit 20d is output to the control unit 15 as an overcurrent detection signal OC. Further, when the clear signal CLR is input from the control unit 15, the latch circuit 20d clears its output to the Hi level.

  The AND circuit 20e outputs a logical product of the output of the latch circuit 20d and the drive signal Sa of the first switching element 5 output from the control unit 15. That is, when the output of the latch circuit 20d is at the Lo level, the signal output to the drive circuit 16 is forcibly set to the Lo level. Similarly, the AND circuit 20f outputs a logical product of the output of the latch circuit 20d and the drive signal Sb of the second switching element 6 output from the control unit 15. That is, when the output of the latch circuit 20d is at the Lo level, the signal output to the drive circuit 17 is forcibly set to the Lo level. Each of the drive signals Sa and Sb is Hi active (the first and second switching elements 5 and 6 are turned on at the Hi level, and the first and second switching elements are turned off at the Lo level). By forcing the signal output to 17 to the Lo level, the first and second switching elements 5 and 6 are forcibly turned off.

  Here, the operation of the control unit 15 when overcurrent is detected by the overcurrent protection circuit 20 will be described. When the control unit 15 detects that the overcurrent detection signal OC is at the Lo level, the control unit 15 turns off the drive signal Sa of the first switching element 5 and the drive signal Sb of the second switching element 6, and the DC load 22. Limit the driving range. Then, the controller 15 outputs a clear signal CLR to the latch circuit 20 after a predetermined time (for example, 10 seconds) if necessary, and cancels the forced-off control of the first and second switching elements 5 and 6. Then, according to the state of the DC voltage Vdc, the drive signal Sa of the first switching element 5 and the drive signal Sb of the second switching element 6 are output, and the operating range restriction of the DC load 22 is released.

  Next, the operation of each state of the first and second switching elements 5 and 6 will be described with reference to FIGS.

  FIG. 3 is a diagram illustrating an operation example when both the first and second switching elements are on. FIG. 4 is a diagram illustrating an operation example when the first switching element is on and the second switching element is off. FIG. 5 is a diagram illustrating an operation example when the first switching element is off and the second switching element is on. FIG. 6 is a diagram illustrating an operation example when both the first and second switching elements are off. 3A, FIG. 4A, FIG. 5A, and FIG. 6A show examples of operation when the power supply current Is ≧ 0, and FIG. 3B, FIG. FIGS. 5B and 6B show an operation example when the power supply current Is <0. In the following description, the voltage Vs of the AC power supply 1 is simply referred to as “power supply voltage”, and the voltage Vc on the input side of the rectifier 3 is referred to as “converter voltage”. In the examples shown in FIGS. 3 to 6, the power source current Is flows in the positive direction from the AC power source 1 to the reactor 2, and the power source voltage Vs, the converter voltage Vc, the voltage Vc 1 across the capacitor 7, the capacitor 8 is positive when the voltage is applied in the direction of the arrows shown in FIGS. 3 to 6.

  When both the first and second switching elements 5 and 6 shown in FIG. 3A are on and Is ≧ 0, AC power source 1 → reactor 2 → diode 4a → first switching element 5 → first The power source current Is flows through the path of the second switching element 6 → the diode 4 d → the AC power source 1. When both the first and second switching elements 5 and 6 shown in FIG. 3B are on and Is <0, the AC power source 1 → the diode 4c → the first switching element 5 → the second. The power source current Is flows through the path of the switching element 6 → the diode 4b → the reactor 2 → the AC power source 1. At this time, since the input terminals of the rectifier 3 are short-circuited (power supply short-circuit mode) regardless of the polarity of the power supply current Is, the order of the diodes 4a to 4d and the first and second switching elements 5 and 6 is increased. If the directional voltage is ignored, the converter voltage Vc = 0.

  When the first switching element 5 shown in FIG. 4A is on, the second switching element 6 is off, and Is ≧ 0, the AC power source 1 → the reactor 2 → the diode 4a → the first switching element 5 The power source current Is flows through the path of the second capacitor 8 → the diode 3 d → the AC power source 1. Further, when the first switching element 5 shown in FIG. 4B is on, the second switching element 6 is off, and Is <0, the AC power source 1 → the diode 4c → the first switching element 5 → The power source current Is flows through the path of the second capacitor 8 → the diode 3 b → the reactor 2 → the AC power source 1. At this time, regardless of the polarity of the power supply current Is, the input terminal of the rectifier 3 is connected to the second capacitor 8 (first voltage doubler rectification mode). Here, when the forward voltages of the diodes 3a to 3d, 4a to 4d and the first switching element 5 are ignored, the converter voltage Vc = Vc2 when Is ≧ 0, and the converter voltage Vc = −when Is <0. Vc2.

  When the first switching element 5 shown in FIG. 5A is off, the second switching element 6 is on, and Is ≧ 0, the AC power source 1 → the reactor 2 → the diode 3a → the first capacitor 7 → The power source current Is flows through the path of the second switching element 6 → the diode 4 d → the AC power source 1. 5B, when the first switching element 5 is off, the second switching element 6 is on, and Is <0, the AC power source 1 → the diode 3c → the first capacitor 7 → the first capacitor The power source current Is flows through the path of the second switching element 6 → the diode 4 b → the reactor 2 → the AC power source 1. At this time, regardless of the polarity of the power supply current Is, the input terminals of the rectifier 3 are connected to the first capacitor 7 (second voltage doubler rectification mode). Here, if the forward voltages of the diodes 3a to 3d, 4a to 4d and the second switching element 6 are ignored, the converter voltage Vc = Vc1 when Is ≧ 0, and the converter voltage Vc = −when Is <0. Vc1.

  When both the first and second switching elements 5 and 6 shown in FIG. 6A are off and Is ≧ 0, AC power source 1 → reactor 2 → diode 3a → first capacitor 7 → second The power source current Is flows through the path of the capacitor 8 → the diode 3 d → the AC power source 1. When both the first and second switching elements 5 and 6 shown in FIG. 6B are off and Is <0, the AC power source 1 → the diode 3c → the first capacitor 7 → the second capacitor The power source current Is flows through the path of the capacitor 8 → the diode 3 b → the reactor 2 → the AC power source 1. At this time, regardless of the polarity of the power supply current Is, the first and second capacitors 7 and 8 are connected in series between the input terminals of the rectifier 3 (full-wave rectification mode). If the forward voltages of the diodes 3a to 3d are ignored, the converter voltage Vc = Vdc = Vc1 + Vc2 when Is ≧ 0, and the converter voltage Vc = −Vdc = − (Vc1 + Vc2) when Is <0.

  Next, the operation of the power supply zero-cross detection circuit 13 will be described with reference to FIG. FIG. 7 is a diagram illustrating an operation example of the power supply zero-cross detection circuit. 7A shows the power supply voltage Vs, and FIG. 7B shows the power supply zero-cross signal ZC that is the output of the power supply zero-cross detection circuit 13.

  As shown in FIG. 7, in the present embodiment, the power supply zero-cross detection circuit 13 outputs a power supply zero-cross signal ZC that becomes a Hi level when the power supply voltage Vs ≧ 0 and becomes a Lo level when the power supply voltage Vs <0. . The control unit 15 detects the timing at which the power supply zero cross signal ZC transitions from the Lo level to the Hi level as the zero cross timing of the power supply voltage Vs.

  Next, the relationship between the power supply voltage Vs and the converter voltage Vc when the power source power factor of the AC power supply 1 is 100% will be described with reference to FIG. FIG. 8 is a diagram showing the relationship between the power supply voltage Vs and the converter voltage Vc when the power supply power factor of the AC power supply 1 is 100%. In FIG. 8, Is is a current vector of the AC power supply 1, Vs is a voltage vector of the AC power supply 1, Vc is a voltage vector between input terminals of the rectifier 3, and “ωs” of ωsLIs is an angular velocity frequency (AC power supply of the AC power supply 1). When the frequency of 1 is fs [Hz], ωs = 2π × fs [rad / s]), “L” is the capacity of the reactor 2.

  When the reactor 2 is considered to have only a pure L component, when the voltage Vs of the AC power supply 1 and the current Is are in phase, the phase difference between the vector Vs and ωsLIs is 90 degrees. By controlling the converter voltage Vc in a substantially sine wave shape so as to maintain this relationship, it is possible to obtain an AC / DC converter having a high power factor while satisfying the harmonic regulation value. Here, the phase difference θc [rad] between the vectors Vs and Vc is realized by controlling the substantially sinusoidal waveform of the converter voltage Vc to be delayed by θc / ωs [s] with reference to the zero cross timing of the power supply zero cross signal ZC. doing.

  Boost control to the target DC voltage Vdc * input to the control unit 15 will be described with reference to FIGS. FIG. 9 is a diagram illustrating an example of the drive signals Sa and Sb near the converter voltage peak when the target DC voltage Vdc * is low. FIG. 10 is a diagram illustrating an example of the drive signals Sa and Sb near the converter voltage peak when the target DC voltage Vdc * is high. 9 and 10, Tc is a unit time, tz_1 and tz_2 are full-wave rectification mode times per unit time Tc, tb1_1 and tb1_2 are first double voltage rectification mode times per unit time Tc, and tb2_1 and tb2_2 are unit times. A second voltage doubler rectification mode time per Tc.

  When the target DC voltage Vdc * is low, as shown in FIG. 9, the first and second switching elements 5 and 6 are controlled so that the ratio of the full-wave rectification mode near the converter voltage peak is increased, and the target DC voltage When Vdc * is high, the first and second switching elements 5 and 6 are controlled so that the ratio between the first and second voltage doubler rectification modes near the converter voltage peak is increased as shown in FIG. . Here, when the control for correcting the voltage between both ends of the first and second capacitors 7 and 8 to be described later to be balanced (hereinafter referred to as “voltage balance correction control”) is not performed, The output time in the voltage doubler rectification mode of 2 is controlled to be the same (tb1_x = tb2_x × 2, x = 1, 2) per unit time Tc (for example, 100 μs).

  Next, voltage balance correction control will be described with reference to FIG. FIG. 11 is a diagram illustrating a voltage unbalanced state of the first and second capacitors.

  As described above, when the first switching element 5 shown in FIG. 4 is on and the second switching element 6 is off, the second terminal between the input terminals of the rectifier 3 is connected regardless of the polarity of the power supply current Is. When the first switching element 5 shown in FIG. 5 is off and the second switching element 6 is on, the power source current Is is connected to the capacitor 8 (first voltage rectification mode). Regardless of the polarity, the input terminals of the rectifier 3 are connected to the first capacitor 7 (second voltage doubler rectification mode). For this reason, for example, when the first and second switching elements 5 and 6 have switching variations and the on-time of the first switching element 5 per unit time is larger than the on-time of the second switching element 6. As shown in FIG. 11, after the start of the step-up operation to the target DC voltage Vdc *, the voltage Vc2 across the second capacitor 8 approaches the DC voltage Vdc, and the voltage Vc1 across the first capacitor 7 is Approaching zero. On the other hand, when the ON time of the first switching element 5 per unit time is smaller than the ON time of the second switching element 6, the second capacitor is started after the start of the step-up operation to the target DC voltage Vdc *. The voltage Vc2 between both ends of 8 approaches 0, and the voltage Vc1 between both ends of the first capacitor 7 approaches the DC voltage Vdc.

  Therefore, in the present embodiment, as the voltage balance correction control, when Vc1 <Vc2, the control for correcting the drive signal Sa so as to shorten the ON time of the first switching element 5, and the second switching Either or both of the controls for correcting the drive signal Sb so as to increase the ON time of the element 6 are performed, and when Vc1> Vc2, the ON time of the first switching element 5 is increased. By performing one or both of the control for correcting the drive signal Sa and the control for correcting the drive signal Sb so as to shorten the on-time of the second switching element 6, Vc1 = Vc2 is established. I try to control it.

  Here, when the first switching element 5 or the second switching element 6 is short-circuited or open, even if the voltage balance correction control described above is performed, the actually failed switching element is in the open state. Alternatively, since control becomes impossible in a short state, the voltage Vc1 across the first capacitor 7 and the voltage Vc2 across the second capacitor 8 cannot be balanced.

  For example, when the AC power supply 1 is applied while the first switching element 5 is short-circuited, only the second capacitor 8 is charged, as shown in FIGS. 4 (a) and 4 (b). The voltage across the first capacitor 7 is Vc1 = 0, and the voltage across the second capacitor 8 is Vc2 = Vdc. When the DC load 22 is continuously operated in this state, a current exceeding the current capacity flows through the reverse voltage prevention diode 9 of the first capacitor 7, and the reverse voltage prevention diode 9 is also damaged. A reverse voltage is applied to the first capacitor 7 and the first capacitor 7 may be damaged. Similarly, when the AC power supply 1 is applied in a state where the second switching element 6 is short-circuited, only the first capacitor 7 is charged as shown in FIGS. 5 (a) and 5 (b). The voltage across the first capacitor 7 is Vc1 = Vdc, and the voltage across the second capacitor 8 is Vc2 = 0. When the DC load 22 is continuously operated in this state, a current exceeding the current capacity flows through the reverse voltage prevention diode 10 of the second capacitor 8 and the reverse voltage prevention diode 10 is also damaged, and the second capacitor 8 A reverse voltage is applied to the second capacitor 8 and the second capacitor 8 may be damaged.

  Further, for example, when control is performed such that the DC voltage Vdc is boosted to the target DC voltage Vdc * in a state where the second switching element 6 is in an open failure, FIGS. 4 (a) and 4 (b). As shown in FIG. 5, only the second capacitor 8 is charged, and the voltage across the first capacitor 7 is Vc1 = 0, and the voltage across the second capacitor 8 is Vc2 = Vdc. In this state, when the AC / DC converter 100 is boosted and the DC load 22 is continuously operated, a current exceeding the current capacity flows through the reverse voltage prevention diode 9 of the first capacitor 7 to prevent the reverse voltage. The diode 9 is also damaged, and a reverse voltage is applied to the first capacitor 7, and the first capacitor 7 may be damaged. Similarly, when control is performed to boost the DC voltage Vdc to the target DC voltage Vdc * in a state where the first switching element 5 is in an open failure, FIGS. 5A and 5B also show. As shown, only the first capacitor 7 is charged, and the voltage across the first capacitor 7 is Vc1 = Vdc and the voltage across the second capacitor 8 is Vc2 = 0. In this state, when the AC / DC converter 100 is boosted and the DC load 22 is continuously operated, a current exceeding the current capacity flows through the reverse voltage prevention diode 10 of the second capacitor 8 to prevent the reverse voltage. The diode 10 is also damaged, and a reverse voltage is applied to the second capacitor 8, and the second capacitor 8 may be damaged.

  Therefore, in the present embodiment, the control unit 15 includes the failure determination unit 15d, and the failure determination unit 15d is used to determine the short failure and the open failure of the first and second switching elements 5 and 6, When it is determined that the first or second switching element 5 or 6 is short-circuited or open-failed, the boost operation of the AC / DC converter 100 is stopped and the operation of the DC load 22 is stopped. A failure is reported.

  Here, a failure determination method for the first and second switching elements 5 and 6 by the failure determination means 15d will be described. In this embodiment, when the first switching element 5 or the second switching element 6 is short-circuited or opened, even if the voltage balance correction control described above is performed, the actually failed switching element is in the open state. Alternatively, since the control is impossible in a short state, the first and second voltages Vc1 of the first capacitor 7 and the voltage Vc2 of the second capacitor 8 cannot be balanced. The failure determination of the switching elements 5 and 6 of 2 is performed.

  In other words, in the present embodiment, the failure determination means 15d determines that the voltage Vc1 between both ends of the first capacitor 7 or the voltage Vc2 between both ends of the second capacitor 8 is equal to or less than a predetermined voltage value Vx (for example, Vx = 50V). When the failure determination condition is satisfied (Vc1 ≦ Vx or Vc2 ≦ Vx), the first switching element 5 or the second switching element 6 has a short circuit failure or an open failure. Is determined. Note that the voltage Vc1 across the first capacitor 7 is equal to the DC voltage Vdc obtained from the output value of the second voltage detection circuit 12 and the second capacitor 8 obtained from the output value of the first voltage detection circuit 11. It can be obtained from the difference between the both-end voltage Vc2.

  Hereinafter, the operation based on the determination result of the failure determination means 15d will be described with reference to the flowchart shown in FIG. FIG. 12 is an operation flowchart based on the determination result of the failure determination unit in the AC / DC converter according to the first embodiment.

  The flow process illustrated in FIG. 12 is performed at predetermined intervals (for example, every 50 ms) while the DC load 22 is operated. Although not shown, the control unit 15 operates the DC load 22 in response to the input of the operation command, and when the DC load 22 is in a state of a predetermined load (for example, 500 W) or more, the AC / DC conversion device. 100 is started, that is, the step-up control to the target DC voltage Vdc * is performed. Further, when performing this boost control, the above-described voltage balance correction control is used in combination. It is assumed that the drive signals Sa and Sb are output at the Lo level before the boost operation of the AC / DC converter is started. However, if either one of the first or second switching elements 5 and 6 is short-circuited before the DC load 22 is operated, the voltage Vc1 across the first capacitor 7 or the second capacitor 8 The voltage Vc <b> 2 between both ends becomes close to 0. Therefore, when the condition of step ST101 in FIG. 12 described later is satisfied, the operation of DC load 22 and the boosting operation are not started.

  The failure determination unit 15d determines whether or not the failure determination condition is satisfied, that is, the voltage Vc1 between both ends of the first capacitor 7 or the voltage Vc2 between both ends of the second capacitor 8 is a predetermined voltage value Vx (for example, Vx = 50V) or less (Vc1 ≦ Vx or Vc2 ≦ Vx) is determined (step ST101).

  When the failure determination condition in the failure determination unit 15d is satisfied, that is, when Vc1 ≦ Vx or Vc2 ≦ Vx is satisfied (step ST101; Yes), the control unit 15 sets the drive signals Sa and Sb as Lo level outputs. Then, the boost operation of AC / DC converter 100 is stopped (step ST102), and the operation of DC load 22 is stopped (step ST103). Then, the LED which is the failure notification means 21 is blinked (failure display) to notify that the first switching element 5 or the second switching element 6 has failed (step ST104).

  Subsequently, the failure determination unit 15d counts the number of times the failure determination of the first switching element 5 or the second switching element 6 is performed (hereinafter referred to as “failure determination number”) (step ST105), and the failure determination It is determined whether or not the number of times is a specified value Nx (for example, Nx = 3 times) or more (step ST106). When the number of failure determinations is Nx or more (step ST106; Yes), the control unit 15 performs a process for prohibiting the operation of the DC load 22 and the start of the boost operation of the AC / DC converter 100 (step ST107). The flow process ends. On the other hand, when the number of times of failure determination is less than Nx (step ST106; No), the control unit 15 operates the DC load 22 and the AC / DC converter 100 after a predetermined time Tx (for example, Tx = 3 minutes). Processing for starting the step-up operation is performed (step ST108), and this flow processing is terminated.

  When failure determination conditions in failure determination means 15d are not satisfied, that is, when neither Vc1 ≦ Vx nor Vc2 ≦ Vx is satisfied (step ST101; No), failure determination means 15d further determines that DC voltage Vdc is the target DC voltage. It is determined whether or not Vdc * or more (Vdc ≧ Vdc *) (step ST109). If the DC voltage Vdc is less than the target DC voltage Vdc * (Vdc <Vdc *) (step ST109; No), this flow. End the process.

  When the DC voltage Vdc is equal to or higher than the target DC voltage Vdc * (Vdc ≧ Vdc *) (step ST109; Yes), the failure determination unit 15d clears the number of times of failure determination (step ST110) and is the failure notification unit 21. The LED is turned on (normal display), the fact that the first switching element 5 and the second switching element 6 are normal is notified (step ST111), and this flow process ends.

  When the fluctuations of the DC voltage Vdc and the voltage Vc2 across the second capacitor 8 are large, these Vdc and Vc2 are filtered (for example, the filter time constant) to the extent that does not hinder the failure determination in the failure determination means 15d. Needless to say, failure determination may be performed using a stable value of 10 ms). In addition, the count of the failure determination times (step ST105), the determination of the failure determination count (step ST106), and the boost operation start processing (step ST108) in the flow process shown in FIG. 12 described above are erroneous determinations in the failure determination means 15d. This is assumed and can be omitted when it is not necessary to consider the erroneous determination in the failure determination means 15d. That is, after the step-up operation of the AC / DC converter 100 and the operation of the DC load 22 are stopped (step ST102, step ST103), the failure of the first switching element 5 or the second switching element 6 is notified (step ST104). Then, a process for prohibiting the operation of the DC load 22 and the start of the step-up operation of the AC / DC converter 100 may be performed (step ST107).

  In the present embodiment, the failure determination means 15d is configured such that the voltage Vc1 between both ends of the first capacitor 7 or the voltage Vc2 between both ends of the second capacitor 8 is equal to or less than a predetermined voltage value Vx (for example, Vx = 50V). When the failure determination condition is satisfied (Vc1 ≦ Vx or Vc2 ≦ Vx), the first switching element 5 or the second switching element 6 has a short circuit failure or an open failure. For example, the voltage Vc1 between both ends of the first capacitor 7 or the voltage Vc2 between both ends of the second capacitor 8 rises to the vicinity of the maximum rated voltage of the first and second capacitors 7 and 8. In this case, it is determined that the first switching element 5 or the second switching element 6 has a short circuit fault or an open fault. It is also conceivable. However, in the state in which the first or second switching element 5 or 6 is in an open failure, even if the boost control is performed so that the target DC voltage Vdc * is obtained, proper boost control cannot be performed. In addition, since the voltage Vc1 across the first capacitor 7 or the voltage Vc2 across the second capacitor 8 is close to the maximum rated voltage of the first and second capacitors 7 and 8, the first switching element 5 or It is difficult to determine that the second switching element 6 has an open failure. In the state where the first switching element 5 or the second switching element 6 is short-circuited, when the boost control is performed so that the target DC voltage Vdc * is obtained, the power supply voltage Vs is high. Since the short-circuit mode occurs, the overcurrent is detected by the overcurrent protection circuit 20, the drive signals Sa and Sb are not output and the Lo level signal is forced, and the first and second switching elements 5 and 6 are forcibly turned off. Thus, the voltage cannot be boosted. Therefore, even when the first switching element 5 or the second switching element 6 is short-circuited, the voltage Vc1 between both ends of the first capacitor 7 or the voltage Vc2 between both ends of the second capacitor 8 is the first voltage. It is difficult to determine that the first switching element 5 or the second switching element 6 is short-circuited because the second capacitors 7 and 8 are close to the maximum rated voltage.

  As described above, according to the AC / DC converter of Embodiment 1, the first and second rectifiers connected in parallel to the AC power supply via the reactor and the output terminals of the first rectifier are connected in series. The first capacitor located on the high potential side and the second capacitor located on the low potential side are connected in series between the output terminal of the second rectifier and the first capacitor and the second capacitor located on the low potential side. The first switching element and the second switching element connected to the connection point of the two capacitors, the first and second switching elements are controlled to perform step-up control of the output voltage value to the DC load, and A control unit that performs voltage balance correction control that maintains the voltage across each of the first and second capacitors in an equilibrium state, and performs a failure determination process for the first and second switching elements during boost control; A failure determination means for performing a short-circuit failure or an open failure when the voltage across either one of the first and second capacitors falls below a specified value. Since the boost control is stopped when it is determined that the operation of the DC load is stopped, the operation of the DC load is also stopped. Therefore, the reverse to the first and second capacitors due to the failure of the first and second switching elements. Since the voltage application can be prevented and the occurrence of secondary breakdown can be suppressed, an inexpensive bipolar electrolytic capacitor can be used, and an inexpensive polar electrolytic capacitor can be used. Since the failure of the switching element 2 can be detected at an early stage, the cause of the failure can be easily determined.

  Further, when it is assumed that the failure determination means erroneously determines the failure of the first or second switching element, the failure determination means has a short failure or an open failure of the first or second switching element. Is less than a specified value (for example, 3 times), the voltage between both ends of the first and second capacitors is set to a specified value (for example, 50 [V]) after the specified time has elapsed since the failure determination. When the voltage exceeds), the operation of the DC load can be started and the boosting operation of the AC / DC converter can be started.

  In addition, since the reference ground of the control unit is connected to the negative output terminal of the first rectifier in a non-insulated manner and is shared with the negative potential of the DC voltage Vdc, for example, an A / D converter is provided as the control unit. When a microcomputer is used, the output voltage values (resistance voltage division values) of the first and second voltage detection circuits can be directly detected by an A / D converter provided in the microcomputer, and the configuration is inexpensive. Can be realized.

  Furthermore, when the failure determination means determines that the first or second switching element has a short-circuit failure or an open failure, the failure determination means is provided to notify the failure, whereby the first or second switching element is provided. It is possible to easily recognize that a failure has occurred.

  In the first embodiment described above, the voltage Vc1 between both ends of the first capacitor 7 or the voltage Vc2 between both ends of the second capacitor 8 is equal to or lower than a predetermined voltage value Vx (for example, Vx = 50V). It is determined that the first switching element 5 or the second switching element 6 has a short-circuit failure or an open-failure by detecting the above. However, the present invention is not limited to this. For example, the DC voltage Vdc The first switching element is detected by detecting that the absolute value of the difference between the value of 1/2 and the value of the voltage Vc2 across the second capacitor 8 is equal to or greater than a predetermined value (for example, 50V). 5 or the failure determination of the second switching element 6 may be performed.

  Moreover, in Embodiment 1 mentioned above, although the structure which equipped with LED as a failure leaving means was shown, it is not limited to this, For example, you may make it alert | report a failure with a buzzer etc.

Embodiment 2. FIG.
FIG. 13 is a diagram of a configuration example of the AC / DC control device according to the second embodiment. In addition, the same code | symbol is attached | subjected to the component which is the same as that of Embodiment 1 demonstrated in FIG. 1, or equivalent, and the detailed description is abbreviate | omitted.

  In the example shown in FIG. 13, instead of the DC load 22, an inverter main circuit 23, a three-phase permanent magnet motor 24, and a compressor 25 are connected to the configuration shown in FIG. 1 described in the first embodiment. The compressor main unit 23 is configured to supply DC power to the inverter main circuit 23, and includes the AC / DC control device 100 a and the inverter main circuit 23.

  FIG. 14 is a diagram illustrating a configuration example of an inverter main circuit. As shown in FIG. 14, the DC voltage Vdc is applied from the AC / DC converter 100 a between the input terminals PN of the inverter main circuit 23, and the permanent magnet motor 24 connected to the output terminals U to W of the inverter main circuit 23. Each phase winding (not shown) is configured to supply three-phase AC power.

  The inverter main circuit 23 includes power switching elements SWa to SWf having insulated gate inputs, diodes Da to Df connected in reverse parallel to the power switching elements SWa to SWf, and a drive circuit GDa for driving the power switching elements SWa to SWf. To GDf. The inverter main circuit 23 can be constituted by, for example, an IPM (Intelligent Power Module).

  The compressor 25 is mechanically connected to a rotor (not shown) of a three-phase permanent magnet motor 24, the permanent magnet motor 24 is driven by the inverter main circuit 23, and the rotor of the permanent magnet motor 24 is The compression operation is performed by rotating.

  As shown in FIG. 13, in the AC / DC converter 100a according to the present embodiment, the reverse voltage prevention diode 9-1 connected in reverse parallel in order to prevent the reverse voltage from being applied to the first capacitor 7. As the reverse voltage prevention diode 10-1 connected in reverse parallel to prevent the reverse voltage from being applied to the second capacitor 8, the current capacity is larger than the current value that can be passed through the inverter main circuit 23. For example, it is assumed that the current capacity of the diodes 3a to 3d constituting the rectifier 3 is equal to or greater than that of the diodes 3a to 3d and cooling (not shown) equal to or greater is performed. However, this is not the case when the current capacity of the diodes 3a to 3d has a sufficient margin for the current value that can flow through the inverter main circuit 23.

  Moreover, in the AC / DC converter 100a according to the present embodiment, the control unit 15-1 has a function of controlling the inverter main circuit 23, and drives the power switching elements SWa to SWf of the inverter main circuit 23. Six drive signals are output to the drive circuits GDa to GDf, respectively. In the first embodiment, the operation of the DC load 22 is stopped when the failure determination means 15d determines that the first or second switching element 5 or 6 has a short failure or an open failure. In this embodiment, the operating range of the compressor 25 is limited. The operation range limitation of the compressor 25 will be described later.

  Next, an operation based on the failure determination result of the failure determination means 15d in the second exemplary embodiment will be described with reference to FIG. FIG. 15 is an operation flowchart based on the determination result of the failure determination unit in the AC / DC converter according to the second embodiment. In addition, the same code | symbol is attached | subjected to the process same or equivalent to the operation | movement based on the determination result of the failure determination means 15d in Embodiment 1 demonstrated in FIG.

  The flow process illustrated in FIG. 15 is performed at predetermined intervals (for example, every 50 ms) while the compressor 25 is operating. Although not shown, the control unit 15-1 operates the compressor 25 in response to the input of the operation command, and when the compressor 25 is in a state of a predetermined load (for example, 500 W) or more, it is AC / DC. The converter 100a starts operating, that is, performs step-up control to the target DC voltage Vdc * described above. Further, when performing this boost control, the voltage balance correction control described in the first embodiment is used together. It is assumed that the drive signals Sa and Sb are output at the Lo level before the operation of the AC / DC converter 100a is started.

  The failure determination unit 15d determines whether or not the failure determination condition is satisfied, that is, the voltage Vc1 between both ends of the first capacitor 7 or the voltage Vc2 between both ends of the second capacitor 8 is a predetermined voltage value Vx (for example, Vx = 50V) or less (Vc1 ≦ Vx or Vc2 ≦ Vx) is determined (step ST101).

  When the failure determination condition in the failure determination means 15d is satisfied, that is, when Vc1 ≦ Vx or Vc2 ≦ Vx is satisfied (step ST101; Yes), the control unit 15-1 sets the drive signals Sa and Sb to the Lo level. The boosting operation of the AC / DC converter 100a is stopped (step ST102), and the operating range of the compressor 25 is limited (step ST103a). Then, the LED which is the failure notification means 21 is blinked (failure display) to notify that the first switching element 5 or the second switching element 6 has failed (step ST104).

  Subsequently, the failure determination unit 15d counts the number of times the failure determination of the first switching element 5 or the second switching element 6 is performed (hereinafter referred to as “failure determination number”) (step ST105), and the failure determination It is determined whether or not the number of times is a specified value Nx (for example, Nx = 3 times) or more (step ST106). When the number of times of failure determination is Nx or more (step ST106; Yes), the control unit 15-1 performs a process for prohibiting the start of the boost operation of the AC / DC converter 100a (step ST107a), and ends this flow process. To do. On the other hand, when the number of times of failure determination is less than Nx (step ST106; No), the control unit 15-1 performs the boosting operation of the AC / DC converter 100a after a predetermined time Tx (for example, Tx = 3 minutes). The process for starting is performed (step ST108a), and this flow process is complete | finished.

  When failure determination conditions in failure determination means 15d are not satisfied, that is, when neither Vc1 ≦ Vx nor Vc2 ≦ Vx is satisfied (step ST101; No), failure determination means 15d further determines that DC voltage Vdc is the target DC voltage. It is determined whether or not Vdc * or more (Vdc ≧ Vdc *) (step ST109). If the DC voltage Vdc is less than the target DC voltage Vdc * (Vdc <Vdc *) (step ST109; No), this flow. The process ends.

  When the DC voltage Vdc is equal to or higher than the target DC voltage Vdc * (Vdc ≧ Vdc *) (step ST109; Yes), the failure determination unit 15d cancels the operation range restriction of the compressor 25 (step ST112), and the number of failure determinations Is cleared (step ST110), the LED which is the failure notification means 21 is turned on (normal display), and the fact that the first switching element 5 and the second switching element 6 are normal is notified (step ST111). This flow process ends.

  In the example shown in FIG. 15, the operation range of the compressor 25 is limited (step ST103a), for example, the AC / DC converter 100a does not perform the boosting operation, that is, the DC voltage Vdc output in the full-wave rectification mode. This indicates that the vehicle can be driven. Here, for example, when both the first and second switching elements 5 and 6 are short-circuited, the power supply short-circuit mode shown in FIG. 3 described in the embodiment is set, and the converter voltage Vc = 0. It is extremely rare for both the first and second switching elements 5 and 6 to short-circuit, and at least one of the first and second switching elements 5 and 6 is normal or has an open failure. If it is in a state, it is possible to supply power in the full-wave rectification mode. When one of the first and second switching elements 5 and 6 is short-circuited, the current capacity of each of the reverse voltage prevention diodes 9-1 and 10-1 is obtained. Since the power can be continuously supplied by increasing the value, the operation range of the compressor 25 is limited as described above, and the compressor 25 can be continuously operated.

  When the fluctuations of the DC voltage Vdc and the voltage Vc2 across the second capacitor 8 are large, these Vdc and Vc2 are filtered (for example, the filter time constant) to the extent that does not hinder the failure determination in the failure determination means 15d. Needless to say, failure determination may be performed using a stable value of 10 ms). In addition, the count of failure determination times (step ST105), the determination of failure determination count (step ST106), and the boost operation start processing (step ST108a) in the flow process shown in FIG. 15 described above are erroneous determinations in the failure determination means 15d. This is assumed and can be omitted when it is not necessary to consider the erroneous determination in the failure determination means 15d. That is, the boosting operation of the AC / DC converter 100a is stopped (step ST102), the operating range of the compressor 25 is limited (step ST103a), and the failure of the first switching element 5 or the second switching element 6 is detected. After the notification (step ST104), a process for prohibiting the start of the boost operation of the AC / DC converter 100a may be performed (step ST107a).

  As described above, according to the AC / DC converter according to the second embodiment, if at least one of the first and second switching elements is normal or is in an open failure state, full-wave rectification is performed. Inverter mains connected as a DC load are provided as reverse voltage prevention diodes connected in reverse parallel to prevent reverse voltage from being applied to the first and second capacitors. Since a current capacity larger than the current value that can be passed through the circuit is used, the operation range of the compressor is limited from that in the normal state, that is, it can be operated with the DC voltage Vdc output in the full-wave rectification mode. By limiting to the above, it is possible to continue the operation of the compressor while suppressing the occurrence of secondary breakdown of the first and second capacitors. Therefore, when applied to an air conditioner in which the refrigerant is circulated by the compressor, it is possible to avoid a situation in which the operation of the air conditioner is impossible until a failure is repaired.

  In the normal state where the first and second switching elements are normal, the voltage balance correction control is operating normally, and the voltage across the first and second capacitors is in an equilibrium state, each reverse voltage Since no current flows through the prevention diode, there is an effect that it can be operated with the same loss as in the first embodiment.

Embodiment 3 FIG.
FIG. 16 is a diagram of a configuration example of the AC / DC control device according to the third embodiment. In addition, the same code | symbol is attached | subjected to the component which is the same as that of Embodiment 1 demonstrated in FIG. 1, and Embodiment 2 demonstrated in FIG. 13, and equivalent, and the detailed description is abbreviate | omitted.

  In the example shown in FIG. 16, the connection point of the first switching element 5 and the second switching element 6, the first capacitor 7, and the second capacitor are compared with the configuration shown in FIG. 1 described in the first embodiment. And a drive circuit 27 that converts the drive signal Sc of the protection switch 26 output from the control unit 15-2 into a voltage that can drive the protection switch 26. In place of the overcurrent protection circuit 20, an overcurrent protection circuit 20-1 is provided, and similarly to the configuration shown in FIG. 13 described in the second embodiment, the inverter main circuit 23, the three-phase permanent magnet motor 24, The compressor 25 is connected to the compressor main circuit 23 and supplied to the inverter main circuit 23. The compressor driving apparatus 2 includes the AC / DC control device 100b and the inverter main circuit 23. 0a is configured. Note that the configuration of the inverter main circuit 23 is the same as that of the second embodiment, and thus the description thereof is omitted here.

  FIG. 17 is a diagram of a configuration example of an overcurrent protection circuit in the AC / DC converter according to the third embodiment. In addition, the same code | symbol is attached | subjected to the component same or equivalent to the overcurrent protection circuit 20 in Embodiment 1 demonstrated in FIG. 2, and the detailed description is abbreviate | omitted.

  In the example shown in FIG. 17, the overcurrent protection circuit 20-1 further includes an AND circuit 20g with respect to the configuration shown in FIG. 2 described in the first embodiment. The AND circuit 20g outputs a logical product of the output of the latch circuit 20d and the drive signal Sc of the protection switch 26 output from the control unit 15-2. That is, when the output of the latch circuit 20d is at the Lo level, the signal output to the drive circuit 27 is forcibly set to the Lo level.

  The control unit 15-2 includes a failure determination unit 15d-1 instead of the failure determination unit 15d described in the first embodiment. In addition to the function described in the first embodiment, the failure determination unit 15d-1 monitors the overcurrent detection signal OC output from the overcurrent protection circuit 20-1 in a failure determination process to be described later. According to the Lo / Hi level of the detection signal OC, the first and second switching elements 5 and 6 have a function of determining an open failure and a short failure.

  The protection switch 26 is configured to be off-controlled when the drive signal Sc output from the control unit 15-2 is at the Lo level, and to be on-controlled at the Hi level. The protection switch 26 may be formed of a semiconductor switching element or a normally open contact that is mechanically controlled to open and close.

  Next, failure determination processing of failure determination means 15d-1 in Embodiment 3 will be described with reference to FIG. FIG. 18 is an operation flowchart of the failure determination unit in the AC / DC converter according to the third embodiment.

  The flow process shown in FIG. 18 is performed when the compressor 25 is in a state of a predetermined load (for example, 500 W) or more while the boost operation of the AC / DC converter 100b is stopped. Before starting the boosting operation of the AC / DC converter 100b, the control unit 15-2 outputs all the drive signals Sa, Sb, and Sc at the Lo level, and the AC / DC converter 100b is in the full-wave rectification mode. And

  When the boost operation of the AC / DC converter 100b is stopped, when the compressor 25 reaches a predetermined load (for example, 500 W) or more, the control unit 15-2 controls the latch circuit 20d of the overcurrent protection circuit 20-1. A clear signal CLR is output (step ST201), and the latch state of the output of the latch circuit 20d is cleared (Hi level).

  Subsequently, the control unit 15-2 sets the drive signal Sa of the first switching element 5 to the Hi level (step ST202) and controls the first switching element 5 to be on.

  Here, when the second switching element 6 is short-circuited, the power supply short-circuit mode shown in FIGS. 3A and 3B is entered, and the first and second power supply voltages Vs are high. Overcurrent flows through the switching elements 5 and 6, and the overcurrent detection signal OC output from the overcurrent protection circuit 20-1 becomes the Lo level. On the other hand, when the second switching element 6 is normal, or when the first switching element 5 or the second switching element 6 has an open failure, the overcurrent detection signal OC becomes Hi level.

  Therefore, failure determination means 15d-1 determines whether or not overcurrent detection signal OC is at the Hi level (step ST203), and when overcurrent detection signal OC is at the Lo level (step ST203; No). Then, it is determined that the second switching element 6 has a short circuit failure (step ST204). Then, the control unit 15-2 sets the drive signals Sa and Sb to the Lo level (step ST205), turns off the first and second switching elements 5 and 6, and ends this flow process. At this time, the AC / DC converter 100b is in the full-wave rectification mode.

  On the other hand, when the overcurrent detection signal OC is at the Hi level (step ST203; Yes), the failure determination unit 15d-1 determines that the second switching element 6 is not short-circuited (step ST206). . Then, the control unit 15-2 sets the drive signal Sa of the first switching element 5 to Lo level (step ST207), turns off the first switching element 5, and sets the drive signal Sb of the second switching element 6 to Hi. As a level (step ST208), the second switching element 6 is turned on.

  Here, when the first switching element 5 is short-circuited, the power supply short-circuit mode shown in FIGS. 3A and 3B is set, and the first and second power supply voltages Vs are high. Overcurrent flows through the switching elements 5 and 6, and the overcurrent detection signal OC output from the overcurrent protection circuit 20-1 becomes the Lo level. On the other hand, when the first switching element 5 is normal or the first switching element 5 or the second switching element 6 has an open failure, the overcurrent detection signal OC becomes Hi level.

  Therefore, failure determination means 15d-1 determines whether or not overcurrent detection signal OC is at the Hi level (step ST209), and when overcurrent detection signal OC is at the Lo level (step ST209; No). Then, it is determined that the first switching element 5 is short-circuited (step ST210). Then, the control unit 15-2 sets the drive signals Sa and Sb to the Lo level (step ST205), turns off the first and second switching elements 5 and 6, and ends this flow process. At this time, the AC / DC converter 100b is in the full-wave rectification mode.

  On the other hand, when the overcurrent detection signal OC is at the Hi level (step ST209; Yes), the failure determination unit 15d-1 determines that the first switching element 5 is not short-circuited (step ST211). . Then, the control unit 15-2 sets the drive signal Sa of the first switching element 5 to the Hi level (step ST212), and turns on both the first and second switching elements 5 and 6.

  Here, when both the first switching element 5 and the second switching element 6 are normal, the power supply short-circuit mode shown in FIGS. 3A and 3B is entered, and the power supply voltage Vs is high. Overcurrent flows through the first and second switching elements 5 and 6 and the overcurrent detection signal OC output from the overcurrent protection circuit 20-1 becomes Lo level. On the other hand, when one or both of the first switching element 5 and the second switching element 6 have an open failure, the overcurrent detection signal OC is at the Lo level.

  Therefore, failure determination means 15d-1 determines whether or not overcurrent detection signal OC is at the Lo level (step ST213), and when overcurrent detection signal OC is at the Hi level (step ST213; No). Then, it is determined that one or both of the first switching element 5 and the second switching element 6 have an open failure (step ST214), and the drive signals Sa and Sb are set to Lo level (step ST205). The flow process ends. At this time, the AC / DC converter 100b is in the full-wave rectification mode.

  On the other hand, when the overcurrent detection signal OC is at the Lo level (step ST213; Yes), the failure determination unit 15d-1 determines that the first and second switching elements 5 and 6 are normal ( Step ST215). Then, the control unit 15-2 temporarily sets the drive signals Sa and Sb to the Lo level (step ST216), and controls the first and second switching elements 5 and 6 to be off, thereby latching the overcurrent protection circuit 20-1 in the latch circuit 20d. Is output (step ST217), the latch state of the output of the latch circuit 20d is cleared (Hi level), the drive signal Sc of the protection switch 26 is set to Hi level (step ST218), and the AC / DC converter 100b The step-up operation is started (step ST219), and this flow process ends.

  Next, an operation based on the failure determination result of the failure determination unit 15d-1 in the third embodiment will be described with reference to FIG. FIG. 19 is an operation flowchart based on the determination result of the failure determination unit in the AC / DC converter according to the third embodiment. In addition, the same code | symbol is attached | subjected to the process same or equivalent to the operation | movement based on the determination result of the failure determination means 15d in Embodiment 2 demonstrated in FIG.

  The flow process shown in FIG. 19 is performed every predetermined period (for example, every 50 ms) while the AC / DC converter 100b is performing a boosting operation.

  The failure determination means 15d determines whether or not the first and second switching elements 5 and 6 have failed using the failure determination result shown in FIG. 18 (step ST101a).

  When the first and second switching elements 5 and 6 are out of order (step ST101a; Yes), the control unit 15-2 limits the operating range of the compressor 25 (step ST103a). Then, the LED which is the failure notification means 21 is blinked (failure display) to notify that the first switching element 5 or the second switching element 6 has failed (step ST104).

  Subsequently, the failure determination means 15d-1 counts the number of times of failure determination of the first switching element 5 or the second switching element 6 (hereinafter referred to as “failure determination number”) (step ST105). It is determined whether or not the number of times of failure determination is a specified value Nx (for example, Nx = 3 times) or more (step ST106). When the number of times of failure determination is Nx or more (step ST106; Yes), the control unit 15-2 performs a process for prohibiting the start of the boost operation of the AC / DC converter 100b (step ST107a), and ends this flow process. To do. On the other hand, when the number of times of failure determination is less than Nx (step ST106; No), the control unit 15-2 performs the boosting operation of the AC / DC converter 100b after a predetermined time Tx (for example, Tx = 3 minutes). The process for starting is performed (step ST108a), and this flow process is complete | finished.

  When the first and second switching elements 5 and 6 are not in failure (step ST101a; No), failure determination means 15d-1 further determines that DC voltage Vdc is equal to or higher than target DC voltage Vdc * (Vdc ≧ Vdc *). It is determined whether or not there is (step ST109), and if the DC voltage Vdc is less than the target DC voltage Vdc * (Vdc <Vdc *) (step ST109; No), this flow processing ends.

  When the DC voltage Vdc is equal to or higher than the target DC voltage Vdc * (Vdc ≧ Vdc *) (step ST109; Yes), the failure determination unit 15d-1 releases the operation range restriction of the compressor 25 (step ST112), and the failure The number of determinations is cleared (step ST110), and the LED serving as the failure notification means 21 is turned on (normal display) to notify that the first switching element 5 and the second switching element 6 are normal (step ST111). ), This flow processing is terminated.

  In the example shown in FIG. 19, limiting the operating range of the compressor 25 (step ST103a) means, for example, that the AC / DC converter 100b does not perform a boosting operation, that is, the DC voltage Vdc output in the full-wave rectification mode. This indicates that the vehicle can be driven. Here, for example, when both the first and second switching elements 5 and 6 are short-circuited, the power supply short-circuit mode shown in FIG. 3 described in the embodiment is set, and the converter voltage Vc = 0. It is extremely rare for both the first and second switching elements 5 and 6 to short-circuit, and at least one of the first and second switching elements 5 and 6 is normal or has an open failure. If it is in a state, it is possible to supply power in the full-wave rectification mode, so by limiting the operating range of the compressor 25 so that it can be operated with the DC voltage Vdc output in the full-wave rectification mode, The compressor 25 can be continuously operated.

  When the fluctuations in the DC voltage Vdc and the voltage Vc2 across the second capacitor 8 are large, the Vdc and Vc2 are filtered so as not to hinder the failure determination in the failure determination means 15d-1 (eg, filter Needless to say, the failure determination may be performed using a stable value having a time constant of 10 ms. Further, the above-described count of failure determination (step ST105), determination of the number of failure determination (step ST106), and boosting operation start processing (step ST108a) in the flow process shown in FIG. This is assumed to be a determination, and can be omitted if it is not necessary to consider an erroneous determination in the failure determination means 15d-1. That is, the boost operation of the AC / DC converter 100b is stopped (step ST102), the operation range of the compressor 25 is limited (step ST103a), and the failure of the first switching element 5 or the second switching element 6 is detected. After the notification (step ST104), a process for prohibiting the start of the boost operation of the AC / DC converter 100a may be performed (step ST107a).

  FIG. 20 is an operation flowchart different from FIG. 19 based on the determination result of the failure determination unit in the AC / DC converter according to the third embodiment. In addition, the same code | symbol is attached | subjected to the process same or equivalent to the operation | movement based on the determination result of the failure determination means 15d-1 demonstrated in FIG.

  In the example shown in FIG. 19 described above, an example in which power is supplied in the full-wave rectification mode when the first and second switching elements 5 and 6 have failed has been shown. However, the example shown in FIG. Now, an example will be described in which the boosting operation is performed using both the full-wave rectification mode and the power supply short-circuit mode in accordance with the failure state of the first and second switching elements 5 and 6 to supply power.

  The flow process shown in FIG. 20 is performed at predetermined intervals (for example, every 50 ms) while the AC / DC converter 100b is performing the boosting operation.

  Failure determination means 15d-1 determines whether or not first switching element 5 or second switching element 6 has an open failure using the failure determination result shown in FIG. 18 (step ST113).

  When the first switching element 5 or the second switching element 6 has an open failure (step ST113; Yes), the control unit 15-2 can be operated with the DC voltage Vdc output in the full-wave rectification mode. As described above, the operation range of the compressor 25 is limited (step ST103b). Then, the LED which is the failure notification means 21 is blinked (failure display) to notify that the first switching element 5 or the second switching element 6 has failed (step ST104).

  Subsequently, the failure determination means 15d-1 counts the number of times of failure determination of the first switching element 5 or the second switching element 6 (hereinafter referred to as “failure determination number”) (step ST105). It is determined whether or not the number of times of failure determination is a specified value Nx (for example, Nx = 3 times) or more (step ST106). When the number of times of failure determination is Nx or more (step ST106; Yes), the control unit 15-2 performs a process for prohibiting the start of the step-up operation of the AC / DC converter 100a (step ST107a), and ends this flow process. To do. On the other hand, when the number of failure determinations is less than Nx (step ST106; No), the control unit 15-2 performs normal boosting of the AC / DC converter 100b after a predetermined time Tx (for example, Tx = 3 minutes). Processing for starting the operation is performed (step ST108a), and this flow processing is terminated.

  When the first switching element 5 or the second switching element 6 does not have an open failure (step ST113; No), the failure determination unit 15d-1 uses the failure determination result shown in FIG. It is determined whether or not the element 5 has a short circuit failure (step ST114).

  When the first switching element 5 has a short circuit failure (step ST114; Yes), the control unit 15-2 performs Lo / Hi control on the drive signal Sb of the second switching element 6 to set the full-wave rectification mode. The step-up operation using the power supply short-circuit mode is started (step ST115), and the target DC voltage value Vdc * is output within a range in which the harmonic regulation value can be cleared by the step-up operation using both the full-wave rectification mode and the power-supply short-circuit mode. The voltage range is limited (step ST116), and the operation range of the compressor 25 is limited so that the DC voltage Vdc obtained by the boost operation can be operated (step ST117). Then, the LED serving as the failure notification means 21 is blinked (failure display) to notify that the first switching element 5 has a short circuit failure (step ST118).

  If the first switching element 5 is not short-circuited (step ST114; No), the failure determination means 15d-1 uses the failure determination result shown in FIG. It is determined whether or not (step ST119).

  When the second switching element 6 has a short-circuit failure (step ST119; Yes), the control unit 15-2 performs Lo / Hi control on the drive signal Sa of the first switching element 5 to set the full-wave rectification mode. The boost operation using the power supply short-circuit mode is started (step ST120), and the target DC voltage value Vdc * is output within a range in which the harmonic regulation value can be cleared by the boost operation using the full-wave rectification mode and the power supply short-circuit mode together. The voltage range is limited (step ST116), and the operation range of the compressor 25 is limited so that the DC voltage Vdc obtained by the boost operation can be operated (step ST117). Then, the LED serving as the failure notification means 21 is blinked (failure display) to notify that the first switching element 5 has a short circuit failure (step ST118).

  When the second switching element 6 is not short-circuited (step ST119; No), the failure determination unit 15d-1 further determines whether the DC voltage Vdc is equal to or higher than the target DC voltage Vdc * (Vdc ≧ Vdc *). If the DC voltage Vdc is less than the target DC voltage Vdc * (Vdc <Vdc *) (step ST109; No), this flow processing is terminated.

  When the DC voltage Vdc is equal to or higher than the target DC voltage Vdc * (Vdc ≧ Vdc *) (step ST109; Yes), the failure determination unit 15d-1 releases the operation range restriction of the compressor 25 (step ST112), and the failure The number of determinations is cleared (step ST110), and the LED serving as the failure notification means 21 is turned on (normal display) to notify that the first switching element 5 and the second switching element 6 are normal (step ST111). ), This flow processing is terminated.

  When the fluctuations in the DC voltage Vdc and the voltage Vc2 across the second capacitor 8 are large, the Vdc and Vc2 are filtered so as not to hinder the failure determination in the failure determination means 15d-1 (eg, filter Needless to say, the failure determination may be performed using a stable value having a time constant of 10 ms. In addition, the above-described count of failure determination (step ST105), determination of failure determination (step ST106), and boost operation start processing (step ST108) in the flow process shown in FIG. This is assumed to be a determination, and can be omitted if it is not necessary to consider an erroneous determination in the failure determination means 15d-1. That is, the boosting operation of AC / DC converter 100b is stopped (step ST102), and the operating range of compressor 25 is limited so that it can be operated with DC voltage Vdc output in the full-wave rectification mode (step ST103b). In addition, after notifying the failure of the first switching element 5 or the second switching element 6 (step ST104), a process for prohibiting the start of the boost operation of the AC / DC converter 100b is performed (step ST107a). Good.

  Further, the boosting operation using both the full-wave rectification mode and the power supply short-circuit mode in FIG. 20 can be realized using a known technique. The present invention is not limited by the step-up operation method using both the full-wave rectification mode and the power supply short-circuit mode.

  As described above, according to the AC / DC converter of Embodiment 3, a protective switch is inserted between the connection point of the first and second capacitors and the connection point of the first and second switching elements. When it is determined that the first or second switching element has failed, the operation can be continued in the full-wave rectification mode with the first and second switching elements and the protection switch being turned off. As in the second embodiment, without causing the secondary breakdown of the first and second capacitors, the operating range of the compressor is limited more than usual, that is, the direct current output in the full-wave rectification mode. By limiting to a state where operation is possible with the voltage Vdc, the compressor can be continuously operated. Therefore, when applied to an air conditioner in which the refrigerant is circulated by the compressor, it is possible to avoid a situation in which the operation of the air conditioner is impossible until a failure is repaired.

  Further, when it is determined that the first or second switching element is short-circuited, the one in which the first and second switching elements are not failed is controlled with the protection switch being turned off. In addition, the boost operation using both the full-wave rectification mode and the power supply short-circuit mode is started, and the target DC voltage value Vdc * can be cleared by the boost operation using the power-supply short-circuit mode and the full-wave rectification mode together. When the operation is continued in the full-wave rectification mode described above by limiting the operation range of the compressor so that the operation can be performed with the DC voltage Vdc obtained by the boost operation. The operation range of the compressor can be expanded more than that.

Embodiment 4 FIG.
FIG. 21 is a diagram of a configuration example of the AC / DC control device according to the fourth embodiment. In addition, the same code | symbol is attached | subjected to the component which is the same as that of Embodiment 3 demonstrated in FIG. 16, or equivalent, and the detailed description is abbreviate | omitted.

  In the example illustrated in FIG. 21, the first voltage detection circuit 11-1 is connected to the AC power supply 1 side with respect to the protection switch 26 with respect to FIG. In place of the resistors 11a, 11b, and 11c constituting the first voltage detection circuit 11 described in the first embodiment, the balance resistors 28a and 28b having the same resistance value are used as the balance resistors of the second capacitor 8, respectively. The inverter main circuit 23, the three-phase permanent magnet motor 24, and the compressor are connected in parallel to the first capacitor 7 and the second capacitor 8 in the same manner as the configuration shown in FIG. 16 described in the third embodiment. 25, the inverter main circuit 23 is supplied with DC power, and includes an AC / DC control device 100c and the inverter main circuit 23. 00b is configured. Note that the configuration of the inverter main circuit 23 is the same as that of the second embodiment, and thus the description thereof is omitted here.

  The first voltage detection circuit 11-1 is configured such that a resistor 11 a-1, a resistor 11 b-1, and a resistor 11 c-1 are connected in series from the high potential side between the output terminals of the rectifier 3. A connection point between the resistor 11 a-1 and the resistor 11 b-1 is connected to a connection point between the first switching element 5, the second switching element 6, and one end of the protection switch 26. As described above, the balance resistors 28a and 28b are provided as the balance resistors of the first capacitor 7 and the second capacitor 8, but during normal operation, the protection switch 26 is on-controlled. The resistance value of the resistor 11a-1 and the combined resistance value of the resistor 11b-1 and the resistor 11c-1 so that the voltage Vc1 between both ends of the first capacitor 7 and the voltage Vc2 between both ends of the second capacitor 8 can be kept in equilibrium. Are substantially matched with each other. A connection point between the resistor 11b-1 and the resistor 11c-1 is connected to an A / D converter 15a included in the control unit 15-3, and the control unit 15-3 includes the resistor 11b-1 and the resistor 11c-1. The voltage Vc2 ′ at the connection point between the first switching element 5 and the second switching element 6 is obtained from the voltage value at the connection point between the first switching element 5 and the second switching element 6. In the example shown in FIG. 21, the first voltage detection circuit 11 is configured by three resistors 11a-1, 11b-1, and 11c-1, but, for example, the resistor 11b-1 and the resistor 11c are illustrated. -1 may be connected in series to form the resistor 11a-1, and the voltage at the connection point between the first switching element 5 and the second switching element 6 may be used. Any known configuration capable of detecting Vc2 ′ may be used, and the present invention is not limited by the configuration of the first voltage detection circuit 11-1.

  The control unit 15-3 includes a failure determination unit 15d-2 instead of the failure determination unit 15d-1 described in the third embodiment.

  In failure determination means 15d-1 in the third embodiment, overcurrent detection signal OC output from overcurrent protection circuit 20-1 is monitored, and the first is determined according to the Lo / Hi level of this overcurrent detection signal OC. Although the open failure and the short failure of the second switching elements 5 and 6 are determined, the failure determination means 15d-2 in the present embodiment protects the AC / DC converter 100c while the boosting operation is stopped. With the switch 26 controlled to be off, the DC voltage Vdc obtained from the output value of the second voltage detection circuit 12, the first switching element 5 obtained from the output value of the first voltage detection circuit 11-1, Based on the relationship with the voltage Vc2 ′ at the connection point with the second switching element 6, the open failure and the short-circuit failure of the first and second switching elements 5 and 6 are determined. It is way.

  Next, the failure determination process of failure determination means 15d-2 in the fourth embodiment will be described with reference to FIGS. FIG. 22 is an operation flowchart of the failure determination unit in the AC / DC converter according to the fourth embodiment. FIG. 23 is an operation flowchart different from FIG. 22 of the failure determination means in the AC / DC converter according to the fourth embodiment. In the failure determination process shown in FIG. 22, a short-circuit failure of the first switching element 5 or the second switching element 6 is determined. In the failure determination process shown in FIG. 23, the first switching element 5 is short-circuited. The failure and the short failure of the second switching element 6 are individually determined.

  The flow processing shown in FIG. 22 and FIG. 23 is performed when the compressor 25 is in a state of a predetermined load (for example, 500 W) or more while the boosting operation of the AC / DC converter 100c is stopped. Before starting the boosting operation of the AC / DC converter 100c, the control unit 15-3 outputs all the drive signals Sa, Sb, and Sc at the Lo level, and the AC / DC converter 100b is in the full-wave rectification mode. And

  Here, in the initial state of the flow processing shown in FIGS. 22 and 23, that is, while the boosting operation of the AC / DC converter 100c is stopped, the first switching element 5, the second switching element 6 and the protection switch 26 are turned on. When the first switching element 5 is short-circuited in the off-controlled state, a resistor 11a-1 is connected in place of the first capacitor 7 in FIGS. 4 (a) and 4 (b). Instead of the second capacitor 8, a series circuit composed of a resistor 11b-1 and a resistor 11c-1 is connected. Therefore, when the power supply voltage Vs is near the peak, the voltage Vc2 ′ obtained from the output value of the first voltage detection circuit 11-1 is a value close to the absolute value of the power supply voltage Vs, and the second voltage detection circuit 12 It becomes a value equal to or higher than the DC voltage Vdc obtained from the output value. On the other hand, when the second switching element 6 has a short circuit failure, a resistor 11a-1 is connected in place of the first capacitor 7 in FIGS. Instead of this, a series circuit composed of the resistor 11b-1 and the resistor 11c-1 is connected. Therefore, when the power supply voltage Vs is near the peak, the voltage Vc2 ′ obtained from the output value of the first voltage detection circuit 11-1 is a value close to the value obtained by subtracting the absolute value of the power supply voltage Vs from the DC voltage Vdc. The value is 0 or less.

  On the other hand, when the first switching element 5 and the second switching element 6 are both normal, or when one or both of the first switching element 5 and the second switching element 6 have an open failure. The voltage Vc2 ′ obtained from the output value of the first voltage detection circuit 11-1 is equal to the half value of the DC voltage Vdc obtained from the output value of the second voltage detection circuit 12.

  That is, the voltage Vc2 ′ obtained from the output value of the first voltage detection circuit 11-1 is a voltage value Vy (for example, Vy) defined in advance as a half value of the DC voltage Vdc obtained from the output value of the second voltage detection circuit 12. = 50 V) (Vc2 ′ ≧ Vdc / 2 + Vy), the first switching element 5 can be regarded as having a short circuit failure, and the first voltage detection circuit 11-1 Is equal to or less than a value obtained by subtracting a predetermined voltage value Vy (for example, Vy = 50 V) from a half value of the DC voltage Vdc obtained from the output value of the second voltage detection circuit 12. (Vc2 ′ ≦ Vdc / 2−Vy), it can be considered that the second switching element 6 is short-circuited.

  Therefore, in the example shown in FIG. 22, if the above two conditional expressions (Vc2 ′ ≧ Vdc / 2 + Vy, Vc2 ′ ≦ Vdc / 2−Vy) are modified to satisfy | Vdc / 2−Vc2 ′ | ≧ Vy, It can be assumed that the first switching element 5 or the second switching element 6 has a short circuit failure, and | Vdc / 2−Vc2 ′ | ≧ Vy is not satisfied, that is, | Vdc / 2−Vc2 ′ | <Vy If this condition is satisfied, it is used that both the first switching element 5 and the second switching element 6 can be regarded as not having a short circuit failure.

  First, the failure determination means 15d-2 determines whether or not | Vdc / 2−Vc2 ′ | <Vy is satisfied when the compressor 25 is in a state of a predetermined load (for example, 500 W) or more (step ST301). , | Vdc / 2−Vc2 ′ | <Vy, ie, | Vdc / 2−Vc2 ′ | ≧ Vy (step ST301; No), the first switching element 5 or the second switching It is determined that the element 6 is short-circuited (step ST302), and this flow process is terminated. At this time, the AC / DC converter 100c is in the full-wave rectification mode.

  On the other hand, when | Vdc / 2−Vc2 ′ | <Vy is satisfied (step ST301; Yes), the failure determination unit 15d-2 detects that both the first switching element 5 and the second switching element 6 are short-circuited. It determines with having not carried out (step ST303). Then, the control unit 15-3 sets the drive signal Sa of the first switching element 5 to the Hi level (step ST304) and controls the first switching element 5 to be on.

  Here, when the first switching element 5 is normal (no open failure), neither the first switching element 5 nor the second switching element 6 has a short circuit failure (step ST303). As described above, when the power supply voltage Vs is near the peak, the voltage Vc2 ′ obtained from the output value of the first voltage detection circuit 11-1 becomes a value close to the absolute value of the power supply voltage Vs, and the second The value is equal to or higher than the DC voltage Vdc obtained from the output value of the voltage detection circuit 12.

  That is, if Vc2 ′ ≧ Vdc / 2 + Vy and | Vdc / 2−Vc2 ′ | ≧ Vy obtained by modifying this are satisfied, it is considered that the first switching element 5 is normal (no open failure). If | Vdc / 2−Vc2 ′ | ≧ Vy is not satisfied, that is, if | Vdc / 2−Vc2 ′ | <Vy is satisfied, it is considered that the first switching element 5 has an open failure. Can do.

  Therefore, failure determination means 15d-2 determines whether or not | Vdc / 2−Vc2 ′ | ≧ Vy is satisfied (step ST305), and | Vdc / 2−Vc2 ′ | ≧ Vy is not satisfied. When Vdc / 2−Vc2 ′ | <Vy (step ST305; No), it is determined that the first switching element 5 has an open failure (step ST306). Then, the control unit 15-3 sets the drive signals Sa and Sb to the Lo level (step ST307), turns off the first and second switching elements 5 and 6, and ends this flow process. At this time, the AC / DC converter 100c is in the full-wave rectification mode.

  On the other hand, when | Vdc / 2−Vc2 ′ | ≧ Vy is satisfied (step ST305; Yes), failure determination means 15d-2 determines that the first switching element 5 is normal (step ST308). . Then, the control unit 15-3 sets the drive signal Sa of the first switching element 5 to Lo level (step ST309), turns off the first switching element 5, and sets the drive signal Sb of the second switching element 6 to Hi. As a level (step ST310), the second switching element 6 is turned on.

  Here, when the second switching element 6 is normal (no open failure), neither the first switching element 5 nor the second switching element 6 has a short-circuit failure (step ST303). As described above, when the power supply voltage Vs is near the peak, the voltage Vc2 ′ obtained from the output value of the first voltage detection circuit 11-1 is a value obtained by subtracting the absolute value of the power supply voltage Vs from the DC voltage Vdc. It becomes a close value and a value of 0 or less.

  That is, if Vc2 ′ ≦ Vdc / 2−Vy or | Vdc / 2−Vc2 ′ | ≧ Vy, which is a modification of Vc2 ′ ≦ Vy, the second switching element 6 is regarded as normal (no open failure). If it does not satisfy | Vdc / 2−Vc2 ′ | ≧ Vy, that is, if | Vdc / 2−Vc2 ′ | <Vy is satisfied, it is considered that the second switching element 6 has an open failure. be able to.

  Therefore, failure determination means 15d-2 determines whether or not | Vdc / 2−Vc2 ′ | ≧ Vy is satisfied (step ST311), and | Vdc / 2−Vc2 ′ | ≧ Vy is not satisfied. If Vdc / 2−Vc2 ′ | <Vy (step ST311; No), it is determined that the second switching element 6 has an open failure (step ST312). Then, the control unit 15-3 sets the drive signals Sa and Sb to the Lo level (step ST307), turns off the first and second switching elements 5 and 6, and ends this flow process. At this time, the AC / DC converter 100c is in the full-wave rectification mode.

  On the other hand, when | Vdc / 2−Vc2 ′ | ≧ Vy is satisfied (step ST311; Yes), the failure determination unit 15d-2 determines that the second switching element 6 is normal (step ST313). . Then, the control unit 15-3 sets the drive signal Sb to Lo level (step ST314), turns off the second switching element 6, and outputs a clear signal CLR to the latch circuit 20d of the overcurrent protection circuit 20-1. (Step ST315) The latch state of the output of the latch circuit 20d is cleared (Hi level), the drive signal Sc of the protection switch 26 is set to Hi level (Step ST316), and the boost operation of the AC / DC converter 100c is started (Step ST317). ), This flow processing is terminated.

  Next, the failure determination process shown in FIG. 23 will be described. In the example shown in FIG. 22, it is impossible to determine which of the first switching element 5 and the second switching element 6 has a short circuit fault. However, in the example shown in FIG. 23, the first switching element 5 has a short circuit fault. From the conditional expression (Vc2 ′ ≧ Vdc / 2 + Vy) that can be regarded as being short and the conditional expression (Vc2 ′ ≦ Vdc / 2−Vy) that can be regarded as short-circuit failure of the second switching element 6 A conditional expression (Vdc / 2−Vc2 ′> − Vy) that can be considered that the first switching element 5 is not short-circuited, and a conditional expression that can be regarded that the second switching element 6 is not short-circuited ( Vdc / 2−Vc2 ′ <Vy) is derived, and the short-circuit failure of the first switching element 5 and the short-circuit failure of the second switching element 6 are determined using these conditional expressions. It shows an example of.

  The failure determination means 15d-2 determines whether or not Vdc / 2−Vc2 ′> − Vy is satisfied when the compressor 25 reaches a predetermined load (for example, 500 W) or more (step ST301a), and Vdc / When 2-Vc2 ′> − Vy is not satisfied, that is, when Vdc / 2−Vc2 ′ ≦ −Vy (step ST301a; No), it is determined that the first switching element 5 has a short circuit failure. (Step ST302a), this flow processing is terminated. At this time, the AC / DC converter 100c is in the full-wave rectification mode.

  When Vdc / 2−Vc2 ′> − Vy is satisfied (step ST301a; Yes), it is determined that the first switching element 5 is not short-circuited (step ST303a).

  Further, failure determination means 15d-2 determines whether or not Vdc / 2−Vc2 ′ <Vy is satisfied (step ST301b), and does not satisfy Vdc / 2−Vc2 ′ <Vy, that is, Vdc / 2−Vc2. If '≧ Vy (step ST301b; No), it is determined that the second switching element 6 has a short-circuit failure (step ST302b), and this flow process ends. At this time, the AC / DC converter 100c is in the full-wave rectification mode.

  When Vdc / 2−Vc2 ′ <Vy is satisfied (step ST301b; Yes), it is determined that the second switching element 6 is not short-circuited (step ST303b).

  The following processing is the same as the failure determination processing shown in FIG.

  Note that the above-described failure determination processing shown in FIGS. 22 and 23 is performed while the step-up operation of the AC / DC converter 100c is stopped, so that the DC voltage obtained from the output value of the second voltage detection circuit 12 is used. Vdc can be regarded as constant under the condition that the power supply voltage Vs is constant. Accordingly, if Vdc / 2−Vy is defined as the first threshold value and Vdc / 2 + Vy is defined as the second threshold value, when both the first switching element 5 and the second switching element 6 are controlled to be off, If Vc2 ′ is equal to or lower than the first threshold value (Vc2 ′ ≦ Vdc / 2−Vy), it can be determined that the second switching element 6 has a short circuit failure, and Vc2 ′ is equal to or higher than the second threshold value. If (Vc2 ′ ≧ Vdc / 2 + Vy), it can be determined that the first switching element 5 has a short circuit failure.

  Further, under the condition that neither the first switching element 5 nor the second switching element 6 is short-circuited (step ST303, step ST303a, step ST303b), the drive signal Sa of the first switching element 5 is set to the Hi level. (Step ST304) When the first switching element 5 is on-controlled, if Vc2 ′ is equal to or higher than the second threshold (Vc2 ′ ≧ Vdc / 2 + Vy), the first switching element 5 is normally operated. It can be determined that the device is operating and no open failure has occurred. Further, under the condition that neither the first switching element 5 nor the second switching element 6 is short-circuited (step ST303, step ST303a, step ST303b), the drive signal Sb of the second switching element 6 is set to the Hi level. (Step ST310) When the second switching element 6 is on-controlled, if Vc2 ′ is equal to or lower than the first threshold (Vc2 ′ ≦ Vdc / 2−Vy), the second switching element 6 is It can be determined that the device operates normally and does not have an open failure. That is, when Vc2 ′ is larger than the first threshold and smaller than the second threshold (Vdc / 2−Vy <Vc2 ′ <Vdc / 2 + Vy), the first switching element 5 and the second switching element 5 It can be determined that all of the switching elements 6 have an open failure.

  Next, an operation based on the failure determination result of the failure determination unit 15d-2 in the fourth embodiment will be described.

  If the short failure of the first switching element 5 or the second switching element 6 is determined by the failure determination operation shown in FIG. 22, the same processing as the flow processing of FIG. 19 described in the third embodiment is performed. Good. Further, when the failure determination operation shown in FIG. 23 individually determines the short failure of the first switching element 5 and the short failure of the second switching element 6, the same process as the flow process of FIG. It is also possible to perform the same processing as the flow processing of FIG. 20 described in the third embodiment.

  When the fluctuations in the DC voltage Vdc and the voltage Vc2 ′ at the connection point between the first switching element 5 and the second switching element 6 are large, the failure determination means 15d-2 uses these Vdc and Vc2 ′ as failure determination. Needless to say, the failure determination may be performed using a stable value obtained by filtering (for example, a filter time constant of 10 ms) to the extent that there is no problem.

  As described above, according to the AC / DC converter of the fourth embodiment, the connection point of the first and second capacitors and the connection point of the first and second switching elements are the same as in the third embodiment. When a protection switch is inserted between the first switching element and the first or second switching element, it is determined that the first or second switching element and the protection switch are open. Therefore, the operation range of the compressor is limited as compared with that in the normal state without causing the occurrence of secondary breakdown of the first and second capacitors. By restricting the DC voltage Vdc output in the wave rectification mode to an operable state, the compressor can be continuously operated. Therefore, when applied to an air conditioner in which the refrigerant is circulated by the compressor, it is possible to avoid a situation in which the operation of the air conditioner is impossible until a failure is repaired.

  Further, when it is determined that the first or second switching element is short-circuited, the one in which the first and second switching elements are not failed is controlled with the protection switch being turned off. In addition, the boost operation using both the full-wave rectification mode and the power supply short-circuit mode is started, and the target DC voltage value Vdc * can be cleared by the boost operation using the power-supply short-circuit mode and the full-wave rectification mode together. When the operation is continued in the full-wave rectification mode described above by limiting the operation range of the compressor so that the operation can be performed with the DC voltage Vdc obtained by the boost operation. The operation range of the compressor can be expanded more than that.

  Further, since it is not necessary to flow an overcurrent through the first and second switching elements when determining the short-circuit failure and the open failure of the first and second switching elements as in the third embodiment, the first and second switching elements There is also an effect that the burden on switching of 2 can be reduced.

  In the above-described embodiment, the effective voltage of the AC power supply is described as being 200V. However, the present invention is not limited to this, and can be applied even when the effective voltage of the AC power supply is 100V, for example. Needless to say.

  Moreover, the inverter main circuit which converts the DC power supplied from the above-described embodiment and the DC power supplied from the AC / DC converter into AC power and drives the permanent magnet motor of the compressor is provided as a DC load. The compressor driving device is suitable for application to an air conditioner having a configuration in which refrigerant is circulated by the compressor, and can achieve each effect described in the above-described embodiment.

  The configurations described in the above embodiments are examples of the configurations of the present invention, and can be combined with other known techniques, and a part of the configurations is omitted without departing from the gist of the present invention. Needless to say, it is possible to change the configuration.

  As described above, the present invention is useful as a technique for preventing reverse voltage application to a capacitor due to a failure of a switching element of an AC / DC converter and suppressing occurrence of secondary breakdown. AC / DC converter configured to convert AC power to be converted into DC power and supply the DC load, a compressor drive apparatus including an inverter main circuit as a DC load of the AC / DC converter, and the compressor drive It is suitable for an air conditioner in which refrigerant is circulated by a compressor driven by the apparatus.

  DESCRIPTION OF SYMBOLS 1 AC power supply, 2 Reactor, 3 1st rectifier, 3a-3d diode, 9,9-1, 10, 10-1 Reverse voltage prevention diode, 4 2nd rectifier, 4a-4d diode, 5 1st switching Element, 6 second switching element, 7 first capacitor, 8 second capacitor, 11, 11-1 first voltage detection circuit, 12 second voltage detection circuit, 13 power supply zero-cross detection circuit, 14, 18 , 19 Current detection unit, 15, 15-1, 15-2, 15-3 control unit, 15a, 15b, 15c A / D converter, 15d, 15d-1, 15d-2 failure determination means, 16, 17, 27 drive circuit, 20, 20-1 overcurrent protection circuit, 20a, 20b comparator, 20c, 20e, 20f, 20g AND circuit, 20d latch circuit, 21 failure indicator (LED), 22 a DC load, 23 inverter main circuit, 24 a three-phase permanent magnet motor, 25 compressor, 26 protection switch, 28a, 28b balancing resistor.

Claims (15)

An AC / DC converter that converts AC power supplied from an AC power source into DC power and supplies it to a DC load,
First and second rectifiers connected in parallel to the AC power supply via a reactor;
Two capacitors connected in series between output terminals of the first rectifier to the DC load;
Two switching elements connected in series between the output terminals of the second rectifier, the connection point being connected to the connection point of the two capacitors;
A control unit for controlling the DC load by controlling the two switching elements to perform step-up control of the output voltage value to the DC load;
With
The controller is
Based on the voltage between both ends of the two capacitors during the boost control, the failure determination of the two switching elements is performed, and it is determined that one of the two switching elements is defective. In this case, the two switching elements are turned off to stop the step-up control and stop the DC load. An AC / DC converter that converts AC power supplied from an AC power source into DC power and supplies it to a DC load,
First and second rectifiers connected in parallel to the AC power supply via a reactor;
Two capacitors connected in series between output terminals of the first rectifier to the DC load;
Two switching elements connected in series between the output terminals of the second rectifier, the connection point being connected to the connection point of the two capacitors;
A control unit for controlling the DC load by controlling the two switching elements to perform step-up control of the output voltage value to the DC load;
With
The controller is
The AC / DC converter is characterized in that the control of the DC load and the step-up operation are not started when the voltage between both ends of at least one of the two capacitors is not more than a specified value. An AC / DC converter that converts AC power supplied from an AC power source into DC power and supplies it to a DC load,
First and second rectifiers connected in parallel to the AC power supply via a reactor;
Two capacitors connected in series between output terminals of the first rectifier to the DC load;
Two switching elements connected in series between the output terminals of the second rectifier, the connection point being connected to the connection point of the two capacitors;
Two reverse voltage prevention diodes connected in reverse parallel to the two capacitors, each having a larger current capacity than a current value that can be passed through the DC load;
A control unit for controlling the DC load by controlling the two switching elements to perform step-up control of the output voltage value to the DC load;
With
The controller is
Based on the voltage between both ends of the two capacitors during the boost control, the failure determination of the two switching elements is performed, and it is determined that one of the two switching elements is defective. In this case, the two switching elements are controlled to be turned off to stop the step-up control, and the operation range of the DC load is restricted from that during normal operation.   When the controller determines that the failure has occurred, if one of the two capacitors has a voltage across a predetermined value or less, one of the two switching elements has failed. The AC / DC converter according to claim 1, wherein the AC / DC converter is determined. An AC / DC converter that converts AC power supplied from an AC power source into DC power and supplies it to a DC load,
First and second rectifiers connected in parallel to the AC power supply via a reactor;
Two capacitors connected in series between output terminals of the first rectifier to the DC load;
Two switching elements connected in series between the output terminals of the second rectifier;
A protective switch inserted between the connection point of the two capacitors and the connection point of the two switching elements;
A control unit for controlling the DC load by controlling the two switching elements to perform step-up control of the output voltage value to the DC load;
With
The controller is
During the period in which the DC load is operating and the boost control is stopped, failure determination of the two switching elements is performed based on the current flowing between the output terminals of the second rectifier, and the two In the case of a switching element failure other than both of the switching elements being short-circuited, the protection switch is turned off, the two switching elements are turned off, and a full-wave rectification state is established. An AC / DC converter characterized in that it is operated with a more restrictive than normal operation.   When the controller determines the failure, the current flowing between the output terminals of the second rectifier is less than a specified value in a state where the two switching elements are on-controlled and the protection switch is off-controlled. 6. The AC / DC converter according to claim 5, wherein one or both of the first and second switching elements are determined to have an open failure.   The controller, when performing the failure determination, turns on one of the two switching elements, turns off the other, and turns off the protection switch, and outputs the second rectifier. When the current flowing between the terminals is equal to or greater than a specified value, it is determined that the other of the two switching elements is short-circuited, the protection switch is turned off, and one of the two switching elements is used to The boost control using both the wave rectification mode and the power supply short-circuit mode is performed, and the target DC voltage of the boost control is limited to an output voltage range in which the harmonic regulation value can be cleared, and the operating range of the DC load is 6. The AC / DC converter according to claim 5, wherein the AC / DC converter is operated in a larger scale than the full-wave rectification state. An AC / DC converter that converts AC power supplied from an AC power source into DC power and supplies it to a DC load,
First and second rectifiers connected in parallel to the AC power supply via a reactor;
Two capacitors connected in series between output terminals of the first rectifier to the DC load;
Two switching elements connected in series between the output terminals of the second rectifier;
A protective switch inserted between the connection point of the two capacitors and the connection point of the two switching elements;
A plurality of resistors connected in series between output terminals of the first rectifier to the DC load, the connection point being connected to a connection point of the two switching elements;
A control unit for controlling the DC load by controlling the two switching elements to perform step-up control of the output voltage value to the DC load;
With
The controller is
The first load voltage between the output terminals of the first rectifier and the negative output terminal of the first rectifier as a reference in a period in which the DC load is operating and the boost control is stopped. Based on the second voltage at the connection point of the two switching elements, the failure determination of the two switching elements is performed, and in the case of a switching element failure other than both of the two switching elements being short-circuited, An AC / DC converter characterized in that a protection switch is controlled to be turned off, a full-wave rectification state in which the two switching elements are controlled to be turned off, and an operating range of the DC load is limited compared to normal operation.   The controller, when performing the failure determination, turns on one of the two switching elements, turns off the other, and turns off the protection switch, and the half value of the first voltage 9. The AC according to claim 8, wherein one of the two switching elements is determined to have an open failure when an absolute value of a value obtained by subtracting the second voltage from the threshold is less than a specified value. DC converter.   The controller, when performing the failure determination, has an absolute value of a value obtained by subtracting the second voltage from a half value of the first voltage in a state where the two switching elements and the protection switch are turned off. When it is equal to or greater than a specified value, it is determined that one of the two switching elements is short-circuited, the protection switch is turned off, and the full-wave rectification mode and the power supply are short-circuited using one of the two switching elements. In addition to performing step-up control in combination with the mode, the target DC voltage of the step-up control is limited to an output voltage range in which the harmonic regulation value can be cleared, and the operating range of the DC load is more than the full-wave rectification state. The AC / DC converter according to claim 8, wherein the AC / DC converter is expanded and operated.   In the failure determination, the controller determines that the failure is not a failure in the failure determination after a lapse of a specified time after the failure determination when the number of times that the failure is determined to be consecutive is less than a specified value. The AC / DC converter according to any one of claims 1 to 10, wherein the step-up control is started when the control is started.   12. The AC / DC converter according to claim 1, wherein a reference ground of the control unit is connected to a negative output terminal of the first rectifier in a non-insulated manner. 13.   13. The AC according to claim 1, further comprising a failure notification unit that notifies the failure when the control unit determines that the switching element has a short failure or an open failure. DC converter. The AC / DC converter according to any one of claims 1 to 13,
As the DC load, an inverter main circuit for driving a permanent magnet motor of a compressor by converting DC power supplied from the AC / DC converter into AC power;
A compressor driving device comprising:   An air conditioner comprising the compressor driving device according to claim 14, wherein refrigerant is circulated by a compressor driven by the compressor driving device.

Images