WO2013094330A1 - Power conversion device - Google Patents

Power conversion device Download PDF

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Publication number
WO2013094330A1
WO2013094330A1 PCT/JP2012/079056 JP2012079056W WO2013094330A1 WO 2013094330 A1 WO2013094330 A1 WO 2013094330A1 JP 2012079056 W JP2012079056 W JP 2012079056W WO 2013094330 A1 WO2013094330 A1 WO 2013094330A1
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WO
WIPO (PCT)
Prior art keywords
phase
ground fault
output
voltage
buffer
Prior art date
Application number
PCT/JP2012/079056
Other languages
French (fr)
Japanese (ja)
Inventor
敬史 小倉
哲 重田
浩明 五十嵐
Original Assignee
日立オートモティブシステムズ株式会社
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Publication of WO2013094330A1 publication Critical patent/WO2013094330A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
    • H02P29/02—Providing protection against overload without automatic interruption of supply
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H02M7/53875—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H02M1/123—Suppression of common mode voltage or current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters

Definitions

  • the present invention relates to a power converter using a semiconductor switching element, and more particularly to a power converter provided with a novel AC current ground fault detector for detecting a ground fault phenomenon.
  • a power conversion device that performs power conversion by an inverter circuit including a semiconductor switching element and supplies the power to a load such as a three-phase induction motor
  • various abnormality detection devices are provided.
  • an overcurrent detection device, an overvoltage detection device, a ground fault detection device, and the like are typical ones.
  • the present invention is directed to a ground fault detection device for detecting an AC current ground fault phenomenon (hereinafter simply referred to as a ground fault phenomenon), and generally between an inverter circuit unit and a three-phase induction motor.
  • the signal of the current sensor for detecting the flowing alternating current is sampled by a microcomputer at a predetermined cycle, and the change degree is monitored to detect the ground fault phenomenon.
  • each phase on the secondary side of the three-phase induction motor is disclosed. It is known to detect the ground fault phenomenon by connecting a resistor to the star and detecting the current or voltage at this neutral point.
  • the detection of the ground fault phenomenon of the conventional alternating current was performed by the software processing of the microcomputer based on the information of the current sensor.
  • a situation in which the ground fault phenomenon cannot be detected occurs depending on the abnormality of the microcomputer and the sampling timing for reading the information of the current sensor.
  • the operation time from the occurrence of the ground fault phenomenon to the protection operation by the protection circuit depends on the processing speed of the microcomputer and the start cycle of the processing task, there are situations where the protection operation against the ground fault phenomenon is not in time. There are concerns about the occurrence.
  • An object of the present invention is to provide a power conversion device including a ground fault detection device that can reliably detect the occurrence of a ground fault phenomenon of an alternating current and does not require a high breakdown voltage.
  • the feature of the present invention is that the output part of the current sensor that detects the current value of the alternating current flowing through the U-phase, V-phase, and W-phase output lines connecting the inverter circuit and the load is connected to a star-connected resistive load.
  • the ground fault is detected by inputting the neutral point output of the resistive load connected in a star to the decision unit, and the operation of the gate drive circuit that drives the inverter circuit is limited by the protection circuit by detecting this ground fault. It is a thing.
  • the output portion of each of the U-phase, V-phase, and W-phase current sensors is connected to a star-connected resistance load, and the neutral point output of the star-connected resistance load is input to the determination device. Therefore, it is possible to reliably cause a ground fault phenomenon, and since a current is supplied from a current sensor to a resistive load, it can be configured as a weak electric circuit, so that it is not necessary to consider the countermeasure for high breakdown voltage in the ground fault detection device. is there.
  • FIG. 1 shows a circuit diagram of a three-phase induction motor drive device for a hybrid vehicle as an example of a power conversion device.
  • the three-phase induction motor drive device for a hybrid vehicle includes a DC power supply 101, a smoothing capacitor 102, an inverter circuit.
  • a smoothing capacitor 102 is connected in parallel with the DC power source 101, and the gate drive unit 106 switches the inverter circuit unit 103 according to a control signal of the motor drive control unit 105 to convert the DC voltage into an AC voltage. Drive control of the three-phase induction motor 104 is performed.
  • the motor drive control unit 105 is interposed between at least the motor control microcomputer 110 and the motor control microcomputer 110 and the gate drive unit 106 that drives the inverter circuit unit 103, and restricts the operation of the gate drive unit 106.
  • the protection logic circuit 108 and the ground fault detection unit 109 are provided.
  • the ground fault detection unit 109 receives an output from a current sensor 107 provided on an output line 111 that supplies an AC output from the inverter circuit unit 103 to the three-phase induction motor 104.
  • the output of the current sensor 107 is also input to the motor control microcomputer 110 and used for phase angle control of the inverter circuit unit 103 and the like.
  • the current sensor 107 does not directly measure the current flowing through the output line 111, but converts the magnetic field generated in proportion to the current into a weak electric system voltage by the Hall element to indirectly detect the current.
  • the current sensor 107 is a voltage output and is used by the motor control microcomputer 110.
  • the output of the current sensor 107 can be directly input to the motor control microcomputer 110.
  • the output of the current sensor 107 is taken in at a predetermined sample timing by the motor control microcomputer 110 and is used after being A / D converted.
  • Current sensors 107 are provided in accordance with the number of output lines 111. Actually, since the output line 111 has U-phase, V-phase, and W-phase, the current sensor 107 also supplies U-phase, V-phase, and W-phase current. Three are provided to detect.
  • the U-phase, V-phase, and W-phase currents are supplied to the star-connected resistance loads 112, 113, 114 of the ground fault detection unit 109. That is, the U-phase current is supplied to the resistance load 112, the V-phase current is supplied to the resistance load 113, and the W-phase current is supplied to the resistance load 114.
  • each resistance load 112, 113, 114 is set to the same resistance value.
  • the output of the neutral point 115 of the resistance load that is star-connected is input to the determiner 116, and the ground fault phenomenon is determined.
  • a voltage is used for the output of the neutral point 115, but it may be converted into a current and used. In the following description, the voltage at the neutral point 115 is used.
  • the inverter circuit unit 103 receives a DC voltage from the DC power source 101, performs PWM (pulse modulation: Pulse Width Modulation) control according to a signal from the motor drive control unit 105, and converts the DC voltage into an arbitrary three-phase AC. Have.
  • PWM pulse modulation: Pulse Width Modulation
  • This inverter circuit unit 103 is configured by switching elements 3a to 3f made of semiconductors by a three-phase full bridge connection.
  • switching element of this embodiment an element on which an IGBT and a reflux diode are mounted is used.
  • the current of each phase of the U phase, V phase and W phase flowing between the inverter circuit unit 103 and the three-phase induction motor 104 is converted into a voltage used in the weak electric system by the current sensor 107, and the motor drive control unit 105 It is input to the motor control microcomputer 110 and also input to the ground fault detection unit 109.
  • the ground fault detection unit 109 is driven by a 5 V power source.
  • the neutral point 115 of the star connection is obtained.
  • the neutral point potential is normally stabilized at a predetermined constant value.
  • the current sensor 107 is a current-voltage conversion ratio of 500 A / V
  • the current measurement range is -1000 A to +1000 A
  • the output voltage is ⁇ 2 V centered on 2.5 V
  • the neutral point potential is about 2.5 V It stabilizes at.
  • the resistance values of the resistance loads 112, 113, and 114 are set to 10 k ⁇ in consideration of the power supply short circuit failure of the output of the current sensor 107. Then, this neutral point 115 is connected to an upper threshold value determiner 201 and a lower threshold value determiner 202 that constitute the determiner 16 as shown in FIG.
  • the + side input terminal voltage of the comparator 203 constituting the upper threshold value judgment unit 201 is determined by the voltage dividing resistance of the resistor 203 and the resistor 204. For example, if the resistor 203 is 2 k ⁇ and the resistor 204 is 3 k ⁇ , the + side input terminal voltage of the comparator 205 is 3V. This + side input terminal voltage is a comparison reference voltage and also serves as an upper threshold.
  • the potential of the neutral point 115 is stable at about 2.5V. For this reason, since the neutral point potential is lower than 3V which is the + side input terminal voltage, the output of the comparator 205 becomes high impedance, 5V is input to the transistor 206 at the final stage, and the ground fault detection signal becomes OFF. Not output.
  • the output is inverted to the low level because it is higher than 3V which is the + side input terminal voltage of the comparator 205. . Therefore, the transistor 206 at the final stage is turned on and a 5V ground fault detection signal is output.
  • the + side input terminal voltage of the comparator 205 changes depending on the resistance values of the resistors 204 and 207, the forward voltage drop of the diode 208, and the low level output voltage of the comparator 205. To do. For example, if the resistance 207 is 13 k ⁇ , the forward voltage drop of the diode 208 is 0.5 V, and the low level output voltage of the comparator 205 is 0.2 V, the + side input terminal voltage is about 2.8 V. As a result, hysteresis can be given to the + side input terminal voltage, and chattering can be prevented even if the potential of the neutral point 115 fluctuates.
  • the negative side input terminal voltage of the comparator 209 constituting the lower threshold value judgment unit 202 is determined by the voltage dividing resistance of the resistor 210 and the resistor 211. For example, if the resistor 2106 is 3 k ⁇ and the resistor 211 is 2 k ⁇ , the negative input terminal voltage of the comparator 209 is 2V.
  • the negative side input terminal voltage is a comparison reference voltage and is a lower threshold value.
  • the potential at the neutral point 115 is stable at about 2.5 V, and thus becomes higher than the negative input terminal voltage of 2 V, and the output of the comparator 209 is high. Impedance.
  • the output of the comparator 209 is high impedance, the transistor 206 at the final stage is turned off and no ground fault detection signal is output.
  • the negative side input terminal voltage of the comparator 209 of the lower threshold determination unit 202 is determined by the resistance values of the resistors 211 and 212 and the collector-emitter voltage Vce of the transistor 213. .
  • the resistor 212 is 13 k ⁇ and Vce is 0.3 V
  • the negative input terminal voltage is about 2.2 V.
  • the resistors connected to the transistors 206 and 213 are adjustment resistors.
  • the resistance of the star-connected resistance load can be reduced.
  • Each threshold can be provided with hysteresis without changing the potential of the neutral point 115.
  • the current of each phase of the U phase, V phase and W phase is detected by a current sensor, and the voltage at the neutral point is detected by applying a voltage proportional to the current of each phase to the star-connected resistance load.
  • a determination device preferably a comparator having an upper threshold value and a lower threshold value, it becomes possible to always detect a ground fault state, and to connect the inverter circuit unit and the three-phase induction motor.
  • the current flowing in the output line to be connected is converted to a voltage that can be used in a weak electric system and applied to a star-connected resistive load, and the neutral point potential obtained by this is determined by a determiner.
  • FIG. 3 shows an embodiment of the protection logic circuit 108 provided in the motor drive control unit 105 when the protection operation of the three-phase open control is performed when the ground fault phenomenon is detected.
  • FIG. 4 shows an embodiment of the protection logic circuit 108 provided in the motor drive control unit 105 when the protection operation of the three-phase short control is performed when a ground fault is detected.
  • the inverter circuit unit 103 is normally controlled by a motor control microcomputer 110 provided in the motor drive control unit 105.
  • the motor control microcomputer 110 functions to perform PWM control by calculating an appropriate switching time of the semiconductor switching element of the inverter circuit unit 103 in order to give an arbitrary torque and rotation speed to the three-phase induction motor.
  • the first buffer 301 and the second buffer 303 constituting the protection logic circuit 108, and the first buffer 301 arranged between them.
  • Three buffers 302a and a fourth buffer 302b are provided.
  • buffers 301, 302 a, 302 b, and 303 function as a blocking function unit that transmits a control signal from the motor control microcomputer 110 to the gate drive unit 106 and blocks transmission of the control signal in the event of an abnormality.
  • Buffers 301 and 303 are provided on all the switching control signal lines of the semiconductor switching elements 3a to 3f constituting the upper and lower arms.
  • the buffer 302a is provided on the switching control signal line of the semiconductor switching elements 3a, 3b, and 3c constituting the upper arm
  • the buffer 302b is on the switching control signal line of the semiconductor switching elements 3d, 3e, and 3f constituting the lower arm. Is provided.
  • Switching control signals for controlling the semiconductor switching elements 3a to 3f output from the motor control microcomputer 110 are input to the gate driving unit 106 through these buffers 301, 302a, 302b, and 303.
  • Buffers 301, 302a, 302b, and 303 are three-state buffers, and a three-phase open signal, a three-phase short signal, or the like is input as a control signal (hereinafter referred to as a trigger signal) that changes the state of each buffer.
  • the trigger signal is not input, and the buffers 301, 302a, 302b, and 303 are in a conductive state, and each semiconductor switching output from the motor control microcomputer 110 is performed.
  • a switching control signal for controlling the elements 3a to 3f passes through the buffers 301, 302a, 302b, and 303 and is output as it is and is transmitted to the gate drive circuit 106.
  • each of the buffers 301, 302a, 302b, and 303 is inverted to a cutoff state (high impedance state).
  • the buffer 301 is cut off, the output side of the buffer 301 (that is, the input side of the buffers 302a and 302b) is pulled up to the high state.
  • the output side of the buffers 302a and 302b (that is, the input side of the buffer 303) is pulled down to the low state.
  • the output side of the buffer 303 that is, the input side of the gate driving unit 109
  • the photocoupler in the gate driving unit 106 becomes non-conductive, so that the switching elements 3a to 3f It becomes OFF.
  • the gate driving unit 106 When the Low signal is input, the gate driving unit 106 turns on the semiconductor switching element (conducting state), and conversely, when the High signal is input, the gate driving unit 106 turns off the semiconductor switching element.
  • Gate operation by performing an open operation or a 3-phase short (upper arm 3-phase short, lower arm 3-phase short) operation in which only the upper arms 3a to 3c or the lower arms (3d to 3f) are turned on and the others are turned off The operation of the drive unit 106 is limited.
  • the three-phase open operation is executed by a three-phase open signal such as the ground fault detection signal 306, the overcurrent detection signal 307, or the overvoltage detection signal 308 detected in the embodiment shown in FIG.
  • the trigger signal for the open operation is input to the buffer 301 via the timer circuit 305.
  • the buffer 301 When the trigger signal is input to the buffer 301 via the timer circuit 305, the buffer 301 is cut off as described above, and the output side of the buffer 301 is in a high state.
  • the buffer 301 is cut off and the buffers 302a, 302b, and 303 are in a conductive state, so that a high signal is input to the gate driving unit 106 for all the semiconductor switching elements 3a to 3f of the upper and lower arms.
  • the semiconductor switching element when a high signal is input to the gate driving unit 106, the semiconductor switching element is turned off (shut off), and when a low signal is input, the semiconductor switching element is turned on (conductive state).
  • a trigger signal 309 for performing either or both of the upper arm three-phase short operation and the lower arm three-phase short operation can be output from a host microcomputer such as a unit, and the overvoltage detection signal 308 and the ground fault detection signal in FIG.
  • Reference numeral 306 denotes a trigger signal for performing a lower arm three-phase short operation.
  • the buffer 301 receives a trigger signal 309 from the host microcomputer, and the buffers 302a and 302b have a trigger signal 309, an overvoltage signal 308, A ground fault signal 306 is input.
  • the timing chart in the case of the upper arm three-phase short circuit is the same as that in the case of the lower arm three-phase short circuit shown in FIG.
  • a three-phase short signal (lower arm three-phase short) from a host microcomputer or the like is input to a buffer 301 and a three-phase short drive signal control logic 304.
  • the output of the buffer 301 is cut off, and as a result, the input side of the buffer 302a and the buffer 302b provided in the subsequent stage of the buffer 301 is pulled up to a high state.
  • the semiconductor switching element when the low signal is input to the gate driving unit 106, the semiconductor switching element is turned on, and when the high signal is input, the semiconductor switching element is turned off.
  • the input side of the buffers 302a and 302b (the output side of the buffer 301) is in a high state. Since the High signal passes through the buffer 303 and is directly input to the gate driving unit 109, the semiconductor switching elements 3a to 3f are turned off. This produces an output as shown in “Output Buffer 301” in FIG.
  • the three-phase short drive signal control logic 304 when a three-phase short signal is input to the three-phase short drive signal control logic 304, the three-phase short drive signal control logic 304 performs a delay operation and is delayed by a predetermined delay time ⁇ t1 from the output cutoff of the buffer 301.
  • the upper arm 3-phase short signal in the case of an upper arm 3-phase short operation
  • the lower arm 3-phase short signal in the case of a lower arm 3-phase short operation
  • FIG. 5 shows the case of a three-phase short in the lower arm, so the output of the buffer 302b is delayed by a predetermined delay time ⁇ t1 from the output cut off of the buffer 301. Blocked.
  • the semiconductor switching elements 3d to 3f when entering the three-phase short operation, first, the three-phase open operation for turning off all the semiconductor switching elements 3a to 3f is performed, and then the semiconductor switching elements 3a to 3c are performed. Alternatively, the semiconductor switching elements 3d to 3f are turned on. (In FIG. 5, the semiconductor switching elements 3d to 3f operate so as to be turned on.) When the three-phase short signal disappears, as shown in “buffer 302b output” in FIG. 5, the buffer 302b (buffer 302a in the case of the upper-arm three-phase short operation) immediately returns to the active state. At this time, since the output side of the buffer 301 is High, the semiconductor switching elements 3d to 3f are turned OFF and switched to the three-phase open state.
  • the three-phase open state is set and then the operation returns to the normal PWM control.
  • the upper and lower arm semiconductor switching elements can be prevented from being short-circuited during the three-phase short-circuit control, and the structure is highly safe. .
  • the dead time value guaranteed by the inverter circuit unit 103 is 5 ⁇ s
  • the three-phase open periods ( ⁇ t1, ⁇ t2) before and after the three-phase short period are at least 5 ⁇ s, so Occurrence can be reliably prevented.
  • the cost can be reduced compared to a configuration using a microcomputer and software.
  • the protection operation can be performed while ensuring a sufficient dead time, leading to an improvement in safety.
  • FIG. 6 is a diagram showing a detailed circuit of the three-phase short drive signal control logic 304.
  • the above-described dead time ⁇ t1 is generated by the circuit 602 and the circuit 603 in FIG.
  • the design constants of the resistors and capacitors provided in the circuits 602 and 603 can be adjusted.
  • control signals from the host microcomputer include the upper arm three-phase short signal for blocking the output of the buffer 302a and the lower arm three-phase short signal for blocking the output of the buffer 302b.
  • the motor drive control unit 105 sets a priority between the upper arm three-phase short signal and the lower arm three-phase short signal by using a three-phase short drive signal control logic 304 as shown in FIG. The upper and lower short circuit is not caused.
  • FIG. 6 a case is considered in which an upper arm three-phase short signal and a lower arm three-phase short signal are simultaneously input from the host microcomputer.
  • the output of the buffer 301 is shut off. For this reason, the upper arm three-phase short signal is not output, and upper and lower short circuits are prevented.
  • the priority of the upper and lower arms can be selected by switching the signal input. Further, an overvoltage detection signal and a ground fault detection signal are also input to the three-phase short drive signal control logic 304, so that a three-phase short signal, an overvoltage detection signal and a ground fault detection signal are simultaneously generated by the host microcomputer. Prevention becomes possible.
  • an alternating current is output from the inverter circuit unit 103 to the three-phase induction motor 104.
  • the output voltage of the current sensor 107 is a sine wave centered at 2.5V. Since the output current from the inverter to the three-phase induction motor is shifted by 120 degrees in the U phase, V phase, and W phase, the output voltage of the current sensor 107 in the U phase, V phase, and W phase is also shifted by 120 degrees. Yes.
  • the neutral point potential of the star connection is stabilized at about 2.5V.
  • the threshold value of the determiner 201 is 3V and the threshold value of the determiner 202 is 2V, the ground fault detection signal is not output, and the buffers 301, 302a, 302b, and 303 of the protection logic circuit 108 are in a conductive state.
  • the PWM signal from the motor control microcomputer 110 is sent to the gate drive unit 106 as it is to drive the three-phase induction motor 104 normally.
  • the output current from the inverter circuit unit 103 leaks from the ground fault point and is disturbed.
  • the output voltage of the current sensor 107 is also disturbed from the sine wave, and the potential of the neutral point 115 of the resistance load star-connected to the current sensor 107 varies from 2.5V.
  • the potential of the fluctuating neutral point 115 exceeds 3V, which is the upper threshold value of the determiner 201, or falls below 2V, which is the lower threshold value of the determiner 202, a ground fault detection signal is output.
  • the protection logic circuit 108 When a ground fault phenomenon is detected by such a ground fault detection device 109, the protection logic circuit 108 performs the following operation.
  • the ground fault detection signal 306 is input to the buffer 301 via the timer circuit 305 of the protection logic circuit 108 as shown in FIG.
  • the operation when the three phases are open is as described above, and all the switching elements 3a to 3f are turned off. In the three-phase open state, all of the switching elements 3a to 3f are turned off, so that no current is supplied to the three-phase induction motor 104 and no ground fault current flows.
  • the ground fault detection signal 306 is input to both the buffer 301 and the three-phase short drive signal control logic 304 via the timer circuit 305 of the protection logic circuit 108. Is done.
  • the operation at the time of three-phase short is as described above.
  • the upper arm three-phase short state in which switching elements 3a to 3c are turned on and the rest is turned off, or the lower arm three phases in which switching elements 3d to 3f are turned on and the rest are turned off. Short circuit.
  • the switching elements 3a to 3c or the switching elements 3d to 3f are turned on and the other switching elements are turned off, so that a current flows between the three-phase induction motor 104 and the switching element in the ON state. It is possible to recirculate, and it is possible to prevent inflow of current via the freewheeling diode.
  • the current sensor 107 of this embodiment uses a current sensor that is insulated by a Hall element, and is thereby insulated from the voltage of the DC power supply 101. Therefore, a ground fault detection unit is used with a weak power system (5V, etc.) power supply. 109 can be configured, and the size and cost can be reduced.
  • the resistors 112, 113, and 114 of the ground fault detection unit 109 are configured by network resistors, the relative error of the resistance values of the resistors 112, 113, and 114 can be reduced to reduce the resistance of the star-connected resistance load. Variation in the potential of the neutral point 115 can be suppressed, and the ground fault phenomenon can be detected with higher accuracy.
  • the ground drive detection unit 109 and the protection logic circuit 108 that performs the protection operation may be built in the gate drive unit 106.
  • the gate since the output of the current sensor 107 is input to the conductive motive drive control unit 105, the gate There is a need to increase the number of signal lines for sending signals from the current sensor 107 to the drive unit 106.
  • the gate drive unit 106 since the gate drive unit 106 is not a weak power source, it is necessary to increase the withstand voltage, and the circuit configuration is expensive. Therefore, it is not preferable.
  • the protection logic circuit 108 can be prevented from malfunctioning.
  • ground fault phenomenon of alternating current has been performed by microcomputer software processing based on the current sensor information, so depending on the abnormality of the microcomputer and the sampling timing for reading the current sensor information, the ground fault phenomenon may be detected.
  • the grounding phenomenon occurs because the operation time from the occurrence of an undetectable situation or the occurrence of an alternating current ground fault to the protection operation by the protection circuit depends on the processing speed of the microcomputer and the start cycle of the processing task. There is a problem that a situation occurs in which the protection operation against the time is not in time.
  • the output part of the current sensor that detects the current value of the alternating current flowing through the U-phase, V-phase, and W-phase output lines connecting between the inverter circuit part and the load such as the electric motor is provided.
  • Connect to a star-connected resistive load and input the neutral point output of the star-connected resistive load to the determiner to detect the ground fault phenomenon.
  • the gate drive circuit that drives the inverter circuit Since the protection logic circuit that restricts the operation is operated, it is possible to reliably cause a ground fault phenomenon and to supply a current from the current sensor to the resistive load. This makes it unnecessary to consider the countermeasures for increasing the breakdown voltage.

Abstract

Alternating-current grounding detection has been carried out by means of microcomputer software processing from the output of current sensors, but there have been situations in which it has not been possible to detect grounding due to an abnormality of a microcomputer or due to the sampling timing of a current sensor. By connecting output units of U-phase, V-phase, and W-phase current sensors to a star-connected resistance load, and inputting a neutral-point output of the star-connected resistance load to a determination unit, grounding can be reliably carried out, and furthermore, because current is supplied to the resistance load from the current sensors, a weak electrical circuit configuration can be implemented and handling increases in withstand voltage does not have to be taken into account.

Description

電力変換装置Power converter
　本発明は半導体スイッチング素子を用いた電力変換装置に係り、特に地絡現象を検出する新規な交流電流の地絡検出装置を備えた電力変換装置に関するものである。 The present invention relates to a power converter using a semiconductor switching element, and more particularly to a power converter provided with a novel AC current ground fault detector for detecting a ground fault phenomenon.
　半導体スイッチング素子を備えたインバータ回路により電力変換を行い、その電力を三相誘導電動機のような負荷に供給する電力変換装置においては、種々の異常検出装置が備えられている。例えば、過電流検出装置や過電圧検出装置、及び地絡検出装置等がその代表的なものである。 In a power conversion device that performs power conversion by an inverter circuit including a semiconductor switching element and supplies the power to a load such as a three-phase induction motor, various abnormality detection devices are provided. For example, an overcurrent detection device, an overvoltage detection device, a ground fault detection device, and the like are typical ones.
　ここで、本発明が対象とするのは交流電流の地絡現象(以下では単に地絡現象という)を検出する地絡検出装置であって、一般にはインバータ回路部と三相誘導電動機の間を流れる交流電流を検出する電流センサの信号をマイクロコンピュータによって所定の周期でサンプリングしてその変化度合を監視して地絡現象を検出していた。 Here, the present invention is directed to a ground fault detection device for detecting an AC current ground fault phenomenon (hereinafter simply referred to as a ground fault phenomenon), and generally between an inverter circuit unit and a three-phase induction motor. The signal of the current sensor for detecting the flowing alternating current is sampled by a microcomputer at a predetermined cycle, and the change degree is monitored to detect the ground fault phenomenon.
　また、この他に三相誘導電動機の二次側の異常を検出するものとして、特開２００６－１４１１０８号公報（特許文献１）にあるように、三相誘導電動機の二次側のそれぞれの相に対して抵抗をスター接続し、この中性点の電流或いは電圧を検出して地絡現象を検出するものが知られている。 In addition to this, as a detection of an abnormality on the secondary side of the three-phase induction motor, as disclosed in Japanese Patent Laid-Open No. 2006-141108 (Patent Document 1), each phase on the secondary side of the three-phase induction motor is disclosed. It is known to detect the ground fault phenomenon by connecting a resistor to the star and detecting the current or voltage at this neutral point.
特開２００６－１４１１０８号公報JP 2006-141108 A
　上述したように、従来の交流電流の地絡現象の検出は電流センサの情報を元にマイクロコンピュータのソフトウエア処理により行っていた。しかしながら、マイクロコンピュータの異常や電流センサの情報を読み取るサンプリングのタイミングによっては地絡現象を検出できない状況が発生する。 As described above, the detection of the ground fault phenomenon of the conventional alternating current was performed by the software processing of the microcomputer based on the information of the current sensor. However, a situation in which the ground fault phenomenon cannot be detected occurs depending on the abnormality of the microcomputer and the sampling timing for reading the information of the current sensor.
　更に、地絡現象が発生してから保護回路による保護動作へ移るまでの動作時間がマイクロコンピュータの処理速度や処理タスクの起動周期に依存しているので地絡現象に対する保護動作が間に合わない状況も発生することが懸念される。 Furthermore, since the operation time from the occurrence of the ground fault phenomenon to the protection operation by the protection circuit depends on the processing speed of the microcomputer and the start cycle of the processing task, there are situations where the protection operation against the ground fault phenomenon is not in time. There are concerns about the occurrence.
　また、特許文献１に記載の技術では三相誘導電動機の負荷側に地絡検出回路を設けているが、各相の抵抗を負荷側と直接的に接続するので検出回路の高耐圧化が要求され、このため地絡検出回路が大型、高コスト化するという課題があった。 Further, in the technique described in Patent Document 1, a ground fault detection circuit is provided on the load side of the three-phase induction motor. However, since the resistance of each phase is directly connected to the load side, a high breakdown voltage of the detection circuit is required. Therefore, there has been a problem that the ground fault detection circuit is large and expensive.
　本発明の目的は、確実に交流電流の地絡現象の発生を検出できると共に、高耐圧化を必要としない地絡検出装置を備えた電力変換装置を提供することにある。 An object of the present invention is to provide a power conversion device including a ground fault detection device that can reliably detect the occurrence of a ground fault phenomenon of an alternating current and does not require a high breakdown voltage.
　本発明の特徴は、インバータ回路と負荷の間を結ぶＵ相、Ｖ相及びＷ相の各出力線を流れる交流電流の電流値を検出する電流センサの出力部をスター結線した抵抗負荷に接続し、スター結線した抵抗負荷の中性点の出力を判定器に入力して地絡現象を検出し、この地絡現象の検出によってインバータ回路を駆動するゲート駆動回路の動作を保護回路によって制限するようにしたものである。 The feature of the present invention is that the output part of the current sensor that detects the current value of the alternating current flowing through the U-phase, V-phase, and W-phase output lines connecting the inverter circuit and the load is connected to a star-connected resistive load. The ground fault is detected by inputting the neutral point output of the resistive load connected in a star to the decision unit, and the operation of the gate drive circuit that drives the inverter circuit is limited by the protection circuit by detecting this ground fault. It is a thing.
　本発明によれば、Ｕ相、Ｖ相及びＷ相の各電流センサの出力部をスター結線した抵抗負荷に接続し、スター結線した抵抗負荷の中性点出力を判定器に入力する構成としたので確実に地絡現象をすることができ、しかも電流センサから抵抗負荷に電流を供給するので弱電系の回路として構成できるので地絡検出装置に高耐圧化の対応を考慮しなくてよくなるものである。 According to the present invention, the output portion of each of the U-phase, V-phase, and W-phase current sensors is connected to a star-connected resistance load, and the neutral point output of the star-connected resistance load is input to the determination device. Therefore, it is possible to reliably cause a ground fault phenomenon, and since a current is supplied from a current sensor to a resistive load, it can be configured as a weak electric circuit, so that it is not necessary to consider the countermeasure for high breakdown voltage in the ground fault detection device. is there.
本発明の一実施例になる地絡検出装置を備えた電力変換装置の構成を示す構成図である。It is a block diagram which shows the structure of the power converter device provided with the ground fault detection apparatus which becomes one Example of this invention. 本発明の一実施例になる地絡検出装置の回路図である。It is a circuit diagram of the ground fault detection apparatus which becomes one Example of this invention. 電力変換装置の保護回路を説明するための回路図である。It is a circuit diagram for demonstrating the protection circuit of a power converter device. 電力変換装置の保護回路を説明するための回路図である。It is a circuit diagram for demonstrating the protection circuit of a power converter device. 保護回路の出力とゲート信号の関係を示すチャート図である。It is a chart figure showing the relation between the output of a protection circuit, and a gate signal. ３相ショート駆動信号制御ロジックの回路図である。It is a circuit diagram of a three-phase short drive signal control logic.
　図1は電力変換装置の一例としてのハイブリッド自動車用の三相誘導電動機駆動装置の回路図を示しており、このハイブリッド自動車用の三相誘導電動機駆動装置は直流電源１０１、平滑コンデンサ１０２、インバータ回路部１０３、三相誘導電動機１０４、電動機駆動制御部１０５、ゲート駆動部１０６等より構成されている。 FIG. 1 shows a circuit diagram of a three-phase induction motor drive device for a hybrid vehicle as an example of a power conversion device. The three-phase induction motor drive device for a hybrid vehicle includes a DC power supply 101, a smoothing capacitor 102, an inverter circuit. The unit 103, the three-phase induction motor 104, the motor drive control unit 105, the gate drive unit 106, and the like.
　そして、直流電源１０１と並列に平滑コンデンサ１０２が接続されており、直流電圧を電動機駆動制御部１０５の制御信号に応じてゲート駆動部１０６がインバータ回路部１０３をスイッチングして交流電圧に変換し、三相誘導電動機１０４を駆動制御するものである。 A smoothing capacitor 102 is connected in parallel with the DC power source 101, and the gate drive unit 106 switches the inverter circuit unit 103 according to a control signal of the motor drive control unit 105 to convert the DC voltage into an AC voltage. Drive control of the three-phase induction motor 104 is performed.
　電動機駆動制御部１０５は少なくとも電動機制御用マイクロコンピュータ１１０と、この電動機制御用マイクロコンピュータ１１０とインバータ回路部１０３を駆動するゲート駆動部１０６との間に介装され、ゲート駆動部１０６の動作を制限する保護ロジック回路１０８及び地絡検出部１０９を備えている。 The motor drive control unit 105 is interposed between at least the motor control microcomputer 110 and the motor control microcomputer 110 and the gate drive unit 106 that drives the inverter circuit unit 103, and restricts the operation of the gate drive unit 106. The protection logic circuit 108 and the ground fault detection unit 109 are provided.
　地絡検出部１０９はインバータ回路部１０３から三相誘導電動機１０４に交流出力を供給する出力線１１１に設けられた電流センサ１０７からの出力が入力されている。 The ground fault detection unit 109 receives an output from a current sensor 107 provided on an output line 111 that supplies an AC output from the inverter circuit unit 103 to the three-phase induction motor 104.
　この電流センサ１０７の出力は電動機制御用マイクロコンピュータ１１０にも入力されており、インバータ回路部１０３の位相角制御等に利用されている。 The output of the current sensor 107 is also input to the motor control microcomputer 110 and used for phase angle control of the inverter circuit unit 103 and the like.
　電流センサ１０７は出力線１１１に流れる電流を直接測定するのではなく、電流に比例して発生する磁界をホール素子によって弱電系の電圧に変換し、間接的に電流検出をしている。尚、電流センサ１０７は電圧出力であり、電動機制御用マイクロコンピュータ１１０で利用される。 The current sensor 107 does not directly measure the current flowing through the output line 111, but converts the magnetic field generated in proportion to the current into a weak electric system voltage by the Hall element to indirectly detect the current. The current sensor 107 is a voltage output and is used by the motor control microcomputer 110.
　したがって、電流センサ１０７の出力は電動機制御用マイクロコンピュータ１１０にも直接的に入力が可能である。この場合には、電動機制御用マイクロコンピュータ１１０によって所定のサンプルタイミングで電流センサ１０７の出力が取り込まれ、Ａ／Ｄ変換されて使用されるものである。 Therefore, the output of the current sensor 107 can be directly input to the motor control microcomputer 110. In this case, the output of the current sensor 107 is taken in at a predetermined sample timing by the motor control microcomputer 110 and is used after being A / D converted.
　電流センサ１０７は出力線１１１の数に応じて設けられており、実際には出力線１１１はＵ相、Ｖ相及びＷ相があるので電流センサ１０７もＵ相、Ｖ相及びＷ相の電流を検出するように３個設けられている。 Current sensors 107 are provided in accordance with the number of output lines 111. Actually, since the output line 111 has U-phase, V-phase, and W-phase, the current sensor 107 also supplies U-phase, V-phase, and W-phase current. Three are provided to detect.
　そして、Ｕ相、Ｖ相及びＷ相の電流は地絡検出部１０９のスター結線された抵抗負荷１１２、１１３、１１４に供給されるように構成されている。つまり、Ｕ相の電流は抵抗負荷１１２に与えられ、Ｖ相の電流は抵抗負荷１１３に与えられ、Ｗ相の電流は抵抗負荷１１４に与えられるものである。ここで、各抵抗負荷１１２、１１３、１１４は同じ抵抗値に設定されている。そして、スター結線された抵抗負荷の中性点１１５の出力は判定器１１６に入力されて地絡現象が判定されるものである。ここで、中性点１１５の出力は電圧を使用しているが、この他に電流に変換して使用するようにしても良い。以下の説明においては中性点１１５の電圧を利用するようにしている。 The U-phase, V-phase, and W-phase currents are supplied to the star-connected resistance loads 112, 113, 114 of the ground fault detection unit 109. That is, the U-phase current is supplied to the resistance load 112, the V-phase current is supplied to the resistance load 113, and the W-phase current is supplied to the resistance load 114. Here, each resistance load 112, 113, 114 is set to the same resistance value. Then, the output of the neutral point 115 of the resistance load that is star-connected is input to the determiner 116, and the ground fault phenomenon is determined. Here, a voltage is used for the output of the neutral point 115, but it may be converted into a current and used. In the following description, the voltage at the neutral point 115 is used.
　インバータ回路部１０３は直流電源１０１からの直流電圧が入力され、電動機駆動制御部１０５の信号に従いＰＷＭ（パルス変調：Pulse Width Modulation）制御を行い、直流電圧を任意の３相交流に変換する機能を有している。 The inverter circuit unit 103 receives a DC voltage from the DC power source 101, performs PWM (pulse modulation: Pulse Width Modulation) control according to a signal from the motor drive control unit 105, and converts the DC voltage into an arbitrary three-phase AC. Have.
　このインバータ回路部１０３は半導体によるスイッチング素子３ａ～３ｆを３相フルブリッジ接続で構成している。本実施形態のスイッチング素子にはＩＧＢＴと還流用ダイオードが搭載されたものを用いている。 This inverter circuit unit 103 is configured by switching elements 3a to 3f made of semiconductors by a three-phase full bridge connection. As the switching element of this embodiment, an element on which an IGBT and a reflux diode are mounted is used.
　インバータ回路部１０３と三相誘導電動機１０４の間に流れるＵ相、Ｖ相及びＷ相の各相の電流は、電流センサ１０７によって弱電系で使用される電圧に変換されて電動機駆動制御部１０５の電動機制御マイクロコンピュータ１１０に入力され、また、地絡検出部１０９へ入力される。 The current of each phase of the U phase, V phase and W phase flowing between the inverter circuit unit 103 and the three-phase induction motor 104 is converted into a voltage used in the weak electric system by the current sensor 107, and the motor drive control unit 105 It is input to the motor control microcomputer 110 and also input to the ground fault detection unit 109.
　次に地絡検出部１０９の具体的な回路構成について図２を用いて説明する。この地絡検出部１０９は５Ｖ電源で駆動されるものであり、Ｕ相、Ｖ相及びＷ相の各電流センサ１０７の出力をスター結線した同一抵抗負荷につなぐと、スター結線の中性点１１５の中性点電位は通常では所定の一定値で安定する。 Next, a specific circuit configuration of the ground fault detection unit 109 will be described with reference to FIG. The ground fault detection unit 109 is driven by a 5 V power source. When the outputs of the U-phase, V-phase, and W-phase current sensors 107 are connected to the same resistance load that is star-connected, the neutral point 115 of the star connection is obtained. The neutral point potential is normally stabilized at a predetermined constant value.
　例えば、電流センサ１０７の仕様が５００Ａ/Ｖの電流電圧変換比で、電流測定範囲が－１０００Ａ～＋１０００Ａ、出力電圧が２．５Ｖを中心に±２Ｖとすると、中性点電位は約２．５Ｖで安定する。 For example, if the specification of the current sensor 107 is a current-voltage conversion ratio of 500 A / V, the current measurement range is -1000 A to +1000 A, and the output voltage is ± 2 V centered on 2.5 V, the neutral point potential is about 2.5 V It stabilizes at.
　本実施例では抵抗負荷１１２、１１３、１１４の抵抗値は電流センサ１０７の出力の電源ショート故障も考慮して１０kΩとする。そして、この中性点１１５を図２のように判定器１６を構成する上側閾値判定器２０１と下側閾値判定器２０２に接続する。 In this embodiment, the resistance values of the resistance loads 112, 113, and 114 are set to 10 kΩ in consideration of the power supply short circuit failure of the output of the current sensor 107. Then, this neutral point 115 is connected to an upper threshold value determiner 201 and a lower threshold value determiner 202 that constitute the determiner 16 as shown in FIG.
　上側閾値判定器２０１を構成する比較器２０３の＋側入力端子電圧は抵抗２０３と抵抗２０４の分圧抵抗によって決まる。例えば抵抗２０３を２ｋΩ、抵抗２０４を３kΩとすると比較器２０５の＋側入力端子電圧は３Ｖとなる。この＋側入力端子電圧は比較基準電圧であり、また上側閾値となるものである。 The + side input terminal voltage of the comparator 203 constituting the upper threshold value judgment unit 201 is determined by the voltage dividing resistance of the resistor 203 and the resistor 204. For example, if the resistor 203 is 2 kΩ and the resistor 204 is 3 kΩ, the + side input terminal voltage of the comparator 205 is 3V. This + side input terminal voltage is a comparison reference voltage and also serves as an upper threshold.
　よって、三相誘導電動機を通常駆動している場合では中性点１１５の電位は約２．５Ｖで安定している。このため、中性点電位が＋側入力端子電圧である３Ｖより低いので比較器２０５の出力はハイインピーダンスとなり、最終段のトランジスタ２０６には５Ｖが入力され、ＯＦＦとなって地絡検出信号は出力されない。 Therefore, when the three-phase induction motor is normally driven, the potential of the neutral point 115 is stable at about 2.5V. For this reason, since the neutral point potential is lower than 3V which is the + side input terminal voltage, the output of the comparator 205 becomes high impedance, 5V is input to the transistor 206 at the final stage, and the ground fault detection signal becomes OFF. Not output.
　一方、地絡事故の影響等によりスター結線された抵抗負荷の中性点１１５の電位が３Ｖを越えると、比較器２０５の＋側入力端子電圧である３Ｖより高いので出力はＬｏｗレベルに反転する。したがって、最終段のトランジスタ２０６はＯＮとなって５Ｖの地絡検出信号が出力されることになる。 On the other hand, if the potential of the neutral point 115 of the resistance load star-connected due to the influence of the ground fault exceeds 3V, the output is inverted to the low level because it is higher than 3V which is the + side input terminal voltage of the comparator 205. . Therefore, the transistor 206 at the final stage is turned on and a 5V ground fault detection signal is output.
　ここで、比較器２０５の出力がＬｏｗレベルとなると比較器２０５の＋側入力端子電圧は抵抗２０４と抵抗２０７の抵抗値とダイオード２０８の順方向電圧降下、比較器２０５のＬｏｗレベル出力電圧によって変化する。例えば、抵抗２０７を１３kΩ、ダイオード２０８の順方向電圧降下を０．５Ｖ、比較器２０５のＬｏｗレベル出力電圧が０．２Ｖだとすると、＋側入力端子電圧は約２．８Ｖとなる。これにより＋側入力端子電圧にヒステリシスを持たせることができ、中性点１１５の電位が変動してもチャタリングを防止できる。 Here, when the output of the comparator 205 becomes low level, the + side input terminal voltage of the comparator 205 changes depending on the resistance values of the resistors 204 and 207, the forward voltage drop of the diode 208, and the low level output voltage of the comparator 205. To do. For example, if the resistance 207 is 13 kΩ, the forward voltage drop of the diode 208 is 0.5 V, and the low level output voltage of the comparator 205 is 0.2 V, the + side input terminal voltage is about 2.8 V. As a result, hysteresis can be given to the + side input terminal voltage, and chattering can be prevented even if the potential of the neutral point 115 fluctuates.
　次に、下側閾値判定器２０２を構成する比較器２０９の－側入力端子電圧は抵抗２１０と抵抗２１１の分圧抵抗によって決まる。例えば、抵抗２１０６を３kΩ、抵抗２１１を２kΩとすると比較器２０９の－側入力端子電圧は２Ｖとなる。この－側入力端子電圧は比較基準電圧であり、また下側閾値となるものである。 Next, the negative side input terminal voltage of the comparator 209 constituting the lower threshold value judgment unit 202 is determined by the voltage dividing resistance of the resistor 210 and the resistor 211. For example, if the resistor 2106 is 3 kΩ and the resistor 211 is 2 kΩ, the negative input terminal voltage of the comparator 209 is 2V. The negative side input terminal voltage is a comparison reference voltage and is a lower threshold value.
　よって、三相誘導電動機を通常駆動している場合では中性点１１５の電位は約２．５Ｖで安定しているので－側入力端子電圧である２Ｖより高くなって比較器２０９の出力はハイインピーダンスとなる。比較器２０９の出力がハイインピーダンスであると最終段のトランジスタ２０６はＯＦＦとなって地絡検出信号は出力されない。 Therefore, when the three-phase induction motor is normally driven, the potential at the neutral point 115 is stable at about 2.5 V, and thus becomes higher than the negative input terminal voltage of 2 V, and the output of the comparator 209 is high. Impedance. When the output of the comparator 209 is high impedance, the transistor 206 at the final stage is turned off and no ground fault detection signal is output.
　一方、地絡事故の影響等によりスター結線された抵抗負荷の中性点１１５の電位が２Ｖを下回ると比較器２０９の出力はＬｏｗレベルに反転する。したがって、最終段のトランジスタ２０６はＯＮとなって５Ｖの地絡検出信号が出力されることになる。 On the other hand, when the potential of the neutral point 115 of the resistance load that is star-connected due to the influence of the ground fault or the like falls below 2V, the output of the comparator 209 is inverted to the low level. Therefore, the transistor 206 at the final stage is turned on and a 5V ground fault detection signal is output.
　比較器２０９の出力がＬｏｗレベルとなると下側閾値判定器２０２の比較器２０９の－側入力端子電圧は、抵抗２１１と抵抗２１２の抵抗値とトランジスタ２１３のコレクタ－エミッタ電圧Ｖｃｅによって決まるようになる。 When the output of the comparator 209 becomes low level, the negative side input terminal voltage of the comparator 209 of the lower threshold determination unit 202 is determined by the resistance values of the resistors 211 and 212 and the collector-emitter voltage Vce of the transistor 213. .
　例えば、抵抗２１２が１３kΩ、Ｖｃｅが０．３Ｖだとすると－側入力端子電圧は約２．２Ｖとなる。これにより－側入力端子電圧にヒステリシスを持たせることができ、チャタリングを防止できる。尚、トランジスタ２０６とトランジスタ２１３に接続された抵抗は調整抵抗である。 For example, if the resistor 212 is 13 kΩ and Vce is 0.3 V, the negative input terminal voltage is about 2.2 V. Thereby, hysteresis can be given to the negative side input terminal voltage and chattering can be prevented. Note that the resistors connected to the transistors 206 and 213 are adjustment resistors.
　図２に示すように、上側閾値判定器２０１と下側閾値判定器２０２のフィードドバック系をスター結線された抵抗負荷の中性点１１５と無関係に構成することで、スター結線された抵抗負荷の中性点１１５の電位を変動させることなく各閾値にヒステリシスを持たせることができる。 As shown in FIG. 2, by configuring the feedback system of the upper threshold determination unit 201 and the lower threshold determination unit 202 independently of the neutral point 115 of the star-connected resistance load, the resistance of the star-connected resistance load can be reduced. Each threshold can be provided with hysteresis without changing the potential of the neutral point 115.
　以上の構成によって、高耐圧化を考慮せずに地絡現象の検出を精度良くおこなうことができる。すなわち、Ｕ相、Ｖ相及びＷ相の各相の電流を電流センサで検出し、この各相の電流に比例した電圧をスター結線された抵抗負荷に与えるようにして中性点の電位を検出し、この中性点電位を判定器、好ましくは上側閾値と下側閾値を有する比較器によって比較することで地絡状態を常に検出することが可能となり、またインバータ回路部と三相誘導電動機を結ぶ出力線に流れる電流を弱電系で使用できる電圧に変換してスター結線された抵抗負荷に与え、これによって得られた中性点の電位を判定器で判定するので上記した高耐圧化を考慮せずに地絡現象の検出を精度良くおこなうことができるという効果を奏することができるものである。これによって、マイクロコンピュータのソフトウエア処理により行っていた地絡検出方法で生じていた、マイクロコンピュータの異常や電流センサの情報を読み取るサンプリングのタイミングによっては地絡を検出できない状況が発生したり、地絡現象が発生してから保護回路による保護動作へ移るまでの動作時間がマイクロコンピュータの処理速度や処理タスクの起動周期に依存しているので地絡現象に対する保護動作が間に合わない状況が発生したりするといった課題を解決できるものである。 With the above configuration, it is possible to accurately detect the ground fault phenomenon without considering high breakdown voltage. That is, the current of each phase of the U phase, V phase and W phase is detected by a current sensor, and the voltage at the neutral point is detected by applying a voltage proportional to the current of each phase to the star-connected resistance load. By comparing this neutral point potential with a determination device, preferably a comparator having an upper threshold value and a lower threshold value, it becomes possible to always detect a ground fault state, and to connect the inverter circuit unit and the three-phase induction motor. The current flowing in the output line to be connected is converted to a voltage that can be used in a weak electric system and applied to a star-connected resistive load, and the neutral point potential obtained by this is determined by a determiner. Thus, it is possible to achieve the effect that the detection of the ground fault phenomenon can be performed with high accuracy. As a result, a ground fault cannot be detected depending on the timing of the sampling that reads the information of the microcomputer abnormality or current sensor, which has occurred in the ground fault detection method performed by the microcomputer software processing. Since the operation time from the occurrence of the fault phenomenon to the protection operation by the protection circuit depends on the processing speed of the microcomputer and the start cycle of the processing task, there may be situations where the protective action against the ground fault phenomenon is not in time. It can solve the problem of doing.
　また、三相誘導電動機の負荷側に地絡検出回路を設けているものでは、各相の抵抗を負荷側と直接接続するので検出回路の高耐圧化が要求され、このため地絡検出回路が大型、高コスト化する、という課題についても解決できるものである。 In addition, in the case where a ground fault detection circuit is provided on the load side of the three-phase induction motor, the resistance of each phase is directly connected to the load side, so a high breakdown voltage of the detection circuit is required. The problem of large size and high cost can also be solved.
　次に、上記した地絡検出装置１０９を用いて電力変換装置の保護を行うためにゲート駆動部１０６の動作を制限する保護ロジック回路１０８の構成について説明する。 Next, the configuration of the protection logic circuit 108 that restricts the operation of the gate driving unit 106 in order to protect the power conversion device using the above-described ground fault detection device 109 will be described.
　図３は地絡現象を検出した際に、３相オープン制御の保護動作を行う場合の電動機駆動制御部１０５に設けた保護ロジック回路１０８の実施形態を示している。 FIG. 3 shows an embodiment of the protection logic circuit 108 provided in the motor drive control unit 105 when the protection operation of the three-phase open control is performed when the ground fault phenomenon is detected.
　図４は地絡を検出した際に、３相ショート制御の保護動作を行う場合の電動機駆動制御部１０５に設けた保護ロジック回路１０８の実施形態を示している。 FIG. 4 shows an embodiment of the protection logic circuit 108 provided in the motor drive control unit 105 when the protection operation of the three-phase short control is performed when a ground fault is detected.
　インバータ回路部１０３は通常では電動機駆動制御部１０５に設けた電動機制御マイクロコンピュータ１１０によって制御されている。電動機制御マイクロコンピュータ１１０は、三相誘導電動機に任意のトルクや回転数を与えるために、インバータ回路部１０３の半導体スイッチング素子の適切なスイッチング時間を演算し、ＰＷＭ制御を行うように機能する。 The inverter circuit unit 103 is normally controlled by a motor control microcomputer 110 provided in the motor drive control unit 105. The motor control microcomputer 110 functions to perform PWM control by calculating an appropriate switching time of the semiconductor switching element of the inverter circuit unit 103 in order to give an arbitrary torque and rotation speed to the three-phase induction motor.
　その結果、三相誘導電動機１０４の各相には交流電圧及び電流が印加され、その速度等が駆動制御される。 As a result, an AC voltage and a current are applied to each phase of the three-phase induction motor 104, and its speed and the like are driven and controlled.
　電動機制御マイクロコンピュータ１１０とゲート駆動部１０６との間のスイッチング制御信号のライン上には、保護ロジック回路１０８を構成する第１のバッファ３０１、第２のバッファ３０３、これらの間に配置された第３のバッファ３０２ａ及び第４のバッファ３０２ｂが設けられている。 On the line of the switching control signal between the motor control microcomputer 110 and the gate driving unit 106, the first buffer 301 and the second buffer 303 constituting the protection logic circuit 108, and the first buffer 301 arranged between them. Three buffers 302a and a fourth buffer 302b are provided.
　これらのバッファ３０１、３０２ａ、３０２ｂ、３０３は電動機制御マイクロコンピュータ１１０からの制御信号をゲート駆動部１０６に伝達したり、異常時に制御信号の伝達を遮断する遮断機能部として作用する。 These buffers 301, 302 a, 302 b, and 303 function as a blocking function unit that transmits a control signal from the motor control microcomputer 110 to the gate drive unit 106 and blocks transmission of the control signal in the event of an abnormality.
　バッファ３０１、３０３は上下アームを構成する半導体スイッチング素子３ａ～３ｆのスイッチング制御信号ライン上の全てに設けられている。 Buffers 301 and 303 are provided on all the switching control signal lines of the semiconductor switching elements 3a to 3f constituting the upper and lower arms.
　一方、バッファ３０２ａは上アームを構成する半導体スイッチング素子３ａ、３ｂ、３ｃのスイッチング制御信号ライン上に設けられ、バッファ３０２ｂは下アームを構成する半導体スイッチング素子３ｄ、３ｅ、３ｆのスイッチング制御信号ライン上に設けられている。 On the other hand, the buffer 302a is provided on the switching control signal line of the semiconductor switching elements 3a, 3b, and 3c constituting the upper arm, and the buffer 302b is on the switching control signal line of the semiconductor switching elements 3d, 3e, and 3f constituting the lower arm. Is provided.
　電動機制御マイクロコンピュータ１１０から出力された各半導体スイッチング素子３ａ～３ｆを制御するスイッチング制御信号は、これらのバッファ３０１、３０２ａ、３０２ｂ、３０３を介してゲート駆動部１０６に入力される。バッファ３０１、３０２ａ、３０２ｂ、３０３は３ステートバッファであって、３相オープン信号や３相ショート信号等が各バッファの状態を変更する制御信号（以下では、トリガ信号と称する）として入力される。 Switching control signals for controlling the semiconductor switching elements 3a to 3f output from the motor control microcomputer 110 are input to the gate driving unit 106 through these buffers 301, 302a, 302b, and 303. Buffers 301, 302a, 302b, and 303 are three-state buffers, and a three-phase open signal, a three-phase short signal, or the like is input as a control signal (hereinafter referred to as a trigger signal) that changes the state of each buffer.
　電力変換装置が正常に動作している場合はトリガ信号が入力されない状態となっており、バッファ３０１、３０２ａ、３０２ｂ、３０３は導通状態であって、電動機制御マイクロコンピュータ１１０から出力された各半導体スイッチング素子３ａ～３ｆを制御するスイッチング制御信号は各バッファ３０１、３０２ａ、３０２ｂ、３０３を通過してそのまま出力されゲート駆動回路１０６に伝達される。 When the power converter is operating normally, the trigger signal is not input, and the buffers 301, 302a, 302b, and 303 are in a conductive state, and each semiconductor switching output from the motor control microcomputer 110 is performed. A switching control signal for controlling the elements 3a to 3f passes through the buffers 301, 302a, 302b, and 303 and is output as it is and is transmitted to the gate drive circuit 106.
　一方、電力変換装置に異常が生じてトリガ信号が入力されると、各バッファ３０１、３０２ａ、３０２ｂ、３０３は遮断状態（ハイインピーダンス状態）に反転される。バッファ３０１が遮断状態となると、バッファ３０１の出力側（すなわち、バッファ３０２ａ、３０２ｂの入力側）はＨｉｇｈ状態にプルアップされる。 On the other hand, when an abnormality occurs in the power conversion apparatus and a trigger signal is input, each of the buffers 301, 302a, 302b, and 303 is inverted to a cutoff state (high impedance state). When the buffer 301 is cut off, the output side of the buffer 301 (that is, the input side of the buffers 302a and 302b) is pulled up to the high state.
　バッファ３０２ａ、３０２ｂが遮断状態となると、バッファ３０２ａ、３０２ｂの出力側（すなわち、バッファ３０３の入力側）はＬｏｗ状態にプルダウンされる。バッファ３０３が遮断状態となると、バッファ３０３の出力側（すなわち、ゲート駆動部１０９の入力側)はハイインピーダンス状態となり、ゲート駆動部１０６内のフォトカプラは非導通となるためスイッチング素子３ａ～３ｆはＯＦＦとなる。 When the buffers 302a and 302b are cut off, the output side of the buffers 302a and 302b (that is, the input side of the buffer 303) is pulled down to the low state. When the buffer 303 is cut off, the output side of the buffer 303 (that is, the input side of the gate driving unit 109) is in a high impedance state, and the photocoupler in the gate driving unit 106 becomes non-conductive, so that the switching elements 3a to 3f It becomes OFF.
　ゲート駆動部１０６はＬｏｗ信号が入力されると半導体スイッチング素子をＯＮ（導通状態）にし、逆に、Ｈｉｇｈ信号が入力されると半導体スイッチング素子をＯＦＦ（遮断状態）にする。 When the Low signal is input, the gate driving unit 106 turns on the semiconductor switching element (conducting state), and conversely, when the High signal is input, the gate driving unit 106 turns off the semiconductor switching element.
　本実施形態では、電力変換装置の異常時の保護動作として、バッファ３０１、３０２ａ、３０２ｂ、３０３の内の特定のバッファ出力を遮断することによって、半導体スイッチング素子３ａ～３ｆを全てＯＦＦにする３相オープン動作や、上アーム３ａ～３ｃ、または下アーム（３ｄ～３ｆ）のみをＯＮにして他をＯＦＦする３相ショート（上アーム３相ショート、下アーム３相ショート）動作を行うようにしてゲート駆動部１０６の動作を制限するものである。 In the present embodiment, as a protection operation in the event of an abnormality of the power conversion device, a three-phase that turns off all of the semiconductor switching elements 3a to 3f by shutting off specific buffer outputs of the buffers 301, 302a, 302b, and 303. Gate operation by performing an open operation or a 3-phase short (upper arm 3-phase short, lower arm 3-phase short) operation in which only the upper arms 3a to 3c or the lower arms (3d to 3f) are turned on and the others are turned off The operation of the drive unit 106 is limited.
　次に、上述した保護ロジック回路１０８を用いた具体的な保護動作として、３相オープン動作、３相ショート動作について説明するが、これらの保護動作は異常状態の種類によって選択されるものである。
『３相オープン動作』
　３相オープン動作は図２に示した実施例で検出される地絡検出信号３０６や、過電流検出信号３０７や、過電圧検出信号３０８等の３相オープン信号によって実行されるものであり、３相オープン動作のトリガ信号はタイマ回路３０５を介してバッファ３０１に入力する。 Next, a three-phase open operation and a three-phase short operation will be described as specific protection operations using the above-described protection logic circuit 108. These protection operations are selected according to the type of abnormal state.
"Three-phase open operation"
The three-phase open operation is executed by a three-phase open signal such as the ground fault detection signal 306, the overcurrent detection signal 307, or the overvoltage detection signal 308 detected in the embodiment shown in FIG. The trigger signal for the open operation is input to the buffer 301 via the timer circuit 305.
　トリガ信号がタイマ回路３０５を介してバッファ３０１に入力されると、上述したようにバッファ３０１は遮断状態とされ、バッファ３０１の出力側はＨｉｇｈ状態となる。 When the trigger signal is input to the buffer 301 via the timer circuit 305, the buffer 301 is cut off as described above, and the output side of the buffer 301 is in a high state.
　一方、バッファ３０２ａ、３０２ｂ、３０３にはトリガ信号が入力されないのでいずれも導通状態となっており、入力された信号はＨｉｇｈ状態及びＬｏｗ状態を変えることなくそのまま出力される。 On the other hand, since no trigger signal is input to the buffers 302a, 302b, and 303, all are in a conductive state, and the input signal is output as it is without changing the High state and the Low state.
　すなわち、３相オープン動作時にはバッファ３０１は遮断状態となり、バッファ３０２ａ、３０２ｂ、３０３は導通状態となっているので上下アームの全ての半導体スイッチング素子３ａ～３ｆに関してＨｉｇｈ信号がゲート駆動部１０６に入力される。その結果、半導体スイッチング素子３ａ～３ｆの全てが遮断状態とされる。 That is, during the three-phase open operation, the buffer 301 is cut off and the buffers 302a, 302b, and 303 are in a conductive state, so that a high signal is input to the gate driving unit 106 for all the semiconductor switching elements 3a to 3f of the upper and lower arms. The As a result, all of the semiconductor switching elements 3a to 3f are cut off.
　尚、上述したようにゲート駆動部１０６にＨｉｇｈ信号が入力されると半導体スイッチング素子はＯＦＦ（遮断状態）とされ、Ｌｏｗ信号が入力されると半導体スイッチング素子はＯＮ（導通状態）とされる。 Note that, as described above, when a high signal is input to the gate driving unit 106, the semiconductor switching element is turned off (shut off), and when a low signal is input, the semiconductor switching element is turned on (conductive state).
　次に、電力変換装置の異常が解消されて正常に復帰すると、トリガ信号の入力がなくなるので、タイマ回路３０５により設定された所定の時間だけバッファ３０１への３相オープン信号の入力が保持された後に、バッファ３０１への３相オープン信号の入力がなくなる。この結果、バッファ３０１への３相オープン信号の入力がなくなるとバッファ３０１は導通状態となって通常のＰＷＭ制御に復帰するようになる。
『３相ショート動作』
　上述したように、３相ショート動作には上アームの３相をショートする場合と、下アームの３相をショートする場合とがあり、本実施例では電動機駆動制御部１０５とは別のエンジンコントロールユニット等の上位マイクロコンピュータから上アーム３相ショート動作と下アーム３相ショート動作の両方あるいはどちらか一方の動作を行うトリガ信号３０９を出せるものとし、過電圧検出信号３０８と図２における地絡検出信号３０６は下アーム３相ショート動作を行うトリガ信号とするものである。 Next, when the abnormality of the power converter is resolved and normal operation is resumed, the trigger signal is no longer input, so the input of the three-phase open signal to the buffer 301 is held for a predetermined time set by the timer circuit 305. Later, there is no input of the three-phase open signal to the buffer 301. As a result, when the three-phase open signal is no longer input to the buffer 301, the buffer 301 becomes conductive and returns to normal PWM control.
"3-phase short operation"
As described above, in the three-phase short operation, there are a case where the three phases of the upper arm are shorted and a case where the three phases of the lower arm are short-circuited. In this embodiment, the engine control different from the motor drive control unit 105 is performed. A trigger signal 309 for performing either or both of the upper arm three-phase short operation and the lower arm three-phase short operation can be output from a host microcomputer such as a unit, and the overvoltage detection signal 308 and the ground fault detection signal in FIG. Reference numeral 306 denotes a trigger signal for performing a lower arm three-phase short operation.
　図４にあるようにバッファ３０１には図３に示す例に加えてに上位マイクロコンピュータからのトリガ信号３０９が入力され、バッファ３０２ａ、３０２ｂには上位マイクロコンピュータからのトリガ信号３０９、過電圧信号３０８、地絡信号３０６が入力されるようになっている。 As shown in FIG. 4, in addition to the example shown in FIG. 3, the buffer 301 receives a trigger signal 309 from the host microcomputer, and the buffers 302a and 302b have a trigger signal 309, an overvoltage signal 308, A ground fault signal 306 is input.
　上述したように、３相ショート動作には上アームの３相をショートする場合と、下アームの３相をショートする場合とがあるが、図５には下アーム３相ショートの場合のタイミングチャートを示している。尚、上アーム３相ショートの場合のタイミングチャートも、図５に示す下アーム３相ショートの場合と同様である。 As described above, there are a case where the three phases of the upper arm are short-circuited and a case where the three phases of the lower arm are short-circuited in the three-phase short operation. FIG. Is shown. The timing chart in the case of the upper arm three-phase short circuit is the same as that in the case of the lower arm three-phase short circuit shown in FIG.
　上位マイクロコンピュータ等からの３相ショート信号（下アーム３相ショート）は、バッファ３０１と３相ショート駆動信号制御ロジック３０４に入力される。３相ショート信号がバッファ３０１に入力されると、バッファ３０１の出力は遮断され、その結果バッファ３０１の後段に設けられているバッファ３０２ａ、バッファ３０２ｂの入力側はＨｉｇｈ状態にプルアップされる。 A three-phase short signal (lower arm three-phase short) from a host microcomputer or the like is input to a buffer 301 and a three-phase short drive signal control logic 304. When the three-phase short signal is input to the buffer 301, the output of the buffer 301 is cut off, and as a result, the input side of the buffer 302a and the buffer 302b provided in the subsequent stage of the buffer 301 is pulled up to a high state.
　上述したように、ゲート駆動部１０６に対してＬｏｗ信号が入力されると半導体スイッチング素子がＯＮされ、Ｈｉｇｈ信号が入力されると半導体スイッチング素子がＯＦＦされるので、３相ショート信号がバッファ３０１に入力されると、上述したようにバッファ３０２ａ、バッファ３０２ｂの入力側（バッファ３０１の出力側）はＨｉｇｈ状態となる。そして、Ｈｉｇｈ信号はバッファ３０３を通過してそのままゲート駆動部１０９に入力されるため、半導体スイッチング素子３ａ～３ｆがＯＦＦされる動作を行なう。図５の「バッファ３０１出力」に示されたような出力を生じる。 As described above, when the low signal is input to the gate driving unit 106, the semiconductor switching element is turned on, and when the high signal is input, the semiconductor switching element is turned off. When input, as described above, the input side of the buffers 302a and 302b (the output side of the buffer 301) is in a high state. Since the High signal passes through the buffer 303 and is directly input to the gate driving unit 109, the semiconductor switching elements 3a to 3f are turned off. This produces an output as shown in “Output Buffer 301” in FIG.
　また、これとは別に３相ショート信号が３相ショート駆動信号制御ロジック３０４に入力されると、３相ショート駆動信号制御ロジック３０４は遅延動作を行ないバッファ３０１の出力遮断より所定遅延時間Δｔ１だけ遅れて上アーム３相ショート信号（上アーム３相ショート動作の場合）もしくは下アーム３相ショート信号（下アーム３相ショート動作の場合）を出力する。 Alternatively, when a three-phase short signal is input to the three-phase short drive signal control logic 304, the three-phase short drive signal control logic 304 performs a delay operation and is delayed by a predetermined delay time Δt1 from the output cutoff of the buffer 301. The upper arm 3-phase short signal (in the case of an upper arm 3-phase short operation) or the lower arm 3-phase short signal (in the case of a lower arm 3-phase short operation) is output.
　その結果、バッファ３０２ａもしくはバッファ３０２ｂの出力が遮断されるが、図５は下アーム３相ショートの場合を示しているので、バッファ３０１の出力遮断より所定遅延時間Δｔ１だけ遅れてバッファ３０２ｂの出力が遮断される。 As a result, the output of the buffer 302a or the buffer 302b is cut off, but FIG. 5 shows the case of a three-phase short in the lower arm, so the output of the buffer 302b is delayed by a predetermined delay time Δt1 from the output cut off of the buffer 301. Blocked.
　バッファ３０２ｂの出力が遮断されると、バッファ３０２ｂの出力側はＬｏｗ状態にプルダウンされる。その結果、図５の「半導体スイッチング素子３ｄ～３ｆ」の状態にあるように、下アームの半導体スイッチング素子３ｄ～３ｆに関してはＬｏｗ信号がゲート駆動部１０６に入力され、半導体スイッチング素子３ｄ～３ｆがＯＮされることになる。 When the output of the buffer 302b is cut off, the output side of the buffer 302b is pulled down to a low state. As a result, as in the state of “semiconductor switching elements 3d to 3f” in FIG. 5, a low signal is input to the gate driving unit 106 for the semiconductor switching elements 3d to 3f in the lower arm, and the semiconductor switching elements 3d to 3f are It will be turned on.
　このように、本実施の形態では、３相ショート動作への突入時においては、最初に全ての半導体スイッチング素子３ａ～３ｆをＯＦＦにする３相オープン動作を行い、その後に半導体スイッチング素子３ａ～３ｃもしくは半導体スイッチング素子３ｄ～３ｆをＯＮするようにしている。（図５では半導体スイッチング素子３ｄ～３ｆをＯＮするように動作する。）
　３相ショート信号がなくなると図５の「バッファ３０２ｂ出力」にあるように、バッファ３０２ｂ（上アーム３相ショート動作の場合にはバッファ３０２ａ）は即座に動通状態に戻る。このとき、バッファ３０１の出力側はＨｉｇｈになっているので半導体スイッチング素子３ｄ～３ｆがＯＦＦされ、３相オープン状態に切り替わる。 As described above, in this embodiment, when entering the three-phase short operation, first, the three-phase open operation for turning off all the semiconductor switching elements 3a to 3f is performed, and then the semiconductor switching elements 3a to 3c are performed. Alternatively, the semiconductor switching elements 3d to 3f are turned on. (In FIG. 5, the semiconductor switching elements 3d to 3f operate so as to be turned on.)
When the three-phase short signal disappears, as shown in “buffer 302b output” in FIG. 5, the buffer 302b (buffer 302a in the case of the upper-arm three-phase short operation) immediately returns to the active state. At this time, since the output side of the buffer 301 is High, the semiconductor switching elements 3d to 3f are turned OFF and switched to the three-phase open state.
　そして、図５の「半導体スイッチング素子３ｄ～３ｆ」の状態にあるように、タイマ回路３０５により設定される時間Δｔ２だけバッファ３０１の出力遮断が保持された後に、バッファ３０１は導通状態に戻り、通常のＰＷＭ制御に復帰する。 Then, as in the state of “semiconductor switching elements 3d to 3f” in FIG. 5, after the output cutoff of the buffer 301 is held for the time Δt2 set by the timer circuit 305, the buffer 301 returns to the conductive state, and the normal state Return to PWM control.
　すなわち、３相ショート動作からの復帰時においては、３相ショート信号がなくなった後は、３相オープンの状態にしてから通常のＰＷＭ制御に復帰するように動作するものである。 That is, at the time of return from the three-phase short operation, after the three-phase short signal disappears, the three-phase open state is set and then the operation returns to the normal PWM control.
　上述のように、本実施の形態では、３相ショート動作の制御を行う際には、実際に半導体スイッチング素子が３相ショートとされる期間の前後に、３相オープンとする期間を設けている。 As described above, in the present embodiment, when the three-phase short operation is controlled, a period in which the three-phase open is provided before and after the period in which the semiconductor switching element is actually short-circuited. .
　すなわち、前後にデッドタイムを生成していることになるため、３相ショート制御の際に、上下アーム半導体スイッチング素子の上下短絡の発生を防止することができ、安全性の高い構成となっている。 That is, since dead times are generated before and after, the upper and lower arm semiconductor switching elements can be prevented from being short-circuited during the three-phase short-circuit control, and the structure is highly safe. .
　例えば、インバータ回路部１０３が保証するデッドタイム値が５μsであるならば、この３相ショート期間の前後の３相オープン期間（Δｔ１、Δｔ２）は最低でも5μs以上を確保することで、上下短絡の発生を確実に防止することができる。 For example, if the dead time value guaranteed by the inverter circuit unit 103 is 5 μs, the three-phase open periods (Δt1, Δt2) before and after the three-phase short period are at least 5 μs, so Occurrence can be reliably prevented.
　また、これら一連の保護ロジック回路１０８やタイマ回路３０５、３相ショート駆動信号制御ロジック３０４をハード系で構成することにより、マイクロコンピュータとソフトを用いた構成に比べてコスト低減を図れる。 Further, by configuring the series of the protection logic circuit 108, the timer circuit 305, and the three-phase short drive signal control logic 304 in a hardware system, the cost can be reduced compared to a configuration using a microcomputer and software.
　更に、マイクロコンピュータの異常時やソフトバグが起きたときでも十分なデッドタイムを確保しながら保護動作を行うことができ、安全性の向上に繋がる。 Furthermore, even when a microcomputer malfunctions or a software bug occurs, the protection operation can be performed while ensuring a sufficient dead time, leading to an improvement in safety.
　図６は、３相ショート駆動信号制御ロジック３０４の詳細回路を示す図である。上述したデッドタイムΔｔ１は、図６の回路６０２および回路６０３により生成される。回路６０２、６０３に設けられた抵抗やキャパシタの設計定数を調整することにより、デッドタイムΔｔ１の長さを調整することができる。 FIG. 6 is a diagram showing a detailed circuit of the three-phase short drive signal control logic 304. The above-described dead time Δt1 is generated by the circuit 602 and the circuit 603 in FIG. By adjusting the design constants of the resistors and capacitors provided in the circuits 602 and 603, the length of the dead time Δt1 can be adjusted.
　上述したように、上位マイクロコンピュータによる制御信号には、バッファ３０２ａの出力を遮断する上アーム３相ショート信号と、バッファ３０２ｂの出力を遮断する下アーム３相ショート信号がある。 As described above, the control signals from the host microcomputer include the upper arm three-phase short signal for blocking the output of the buffer 302a and the lower arm three-phase short signal for blocking the output of the buffer 302b.
　しかし、この二つの信号が同時に出力された場合、上下短絡を引き起こすことが考えられる。そこで、電動機駆動制御部１０５では、図６に示すような３相ショート駆動信号制御ロジック３０４を用いることにより、上アーム３相ショート信号と下アーム３相ショート信号との間に優先度を設定し、上下短絡に至らないようにしている。 However, if these two signals are output at the same time, it is possible to cause a vertical short circuit. Therefore, the motor drive control unit 105 sets a priority between the upper arm three-phase short signal and the lower arm three-phase short signal by using a three-phase short drive signal control logic 304 as shown in FIG. The upper and lower short circuit is not caused.
　図６において、上位マイクロコンピュータから上アーム３相ショート信号と下アーム３相ショート信号とが同時に入力された場合を考える。メインマイクロコンピュータから下アーム３相ショート信号が出力されると、バッファ３０１の出力が遮断される。そのため、上アーム３相ショート信号は出力されず、上下短絡が防止される。 In FIG. 6, a case is considered in which an upper arm three-phase short signal and a lower arm three-phase short signal are simultaneously input from the host microcomputer. When the lower arm three-phase short signal is output from the main microcomputer, the output of the buffer 301 is shut off. For this reason, the upper arm three-phase short signal is not output, and upper and lower short circuits are prevented.
　尚、この上下アームの優先度は信号入力を入れ替えることで選択可能である。更に、過電圧検出信号や地絡検出信号も３相ショート駆動信号制御ロジック３０４に入力することで、上位マイクロコンピュータによる３相ショート信号と過電圧検出信号、地絡検出信号が同時に発生したときの上下短絡防止が可能となる。 The priority of the upper and lower arms can be selected by switching the signal input. Further, an overvoltage detection signal and a ground fault detection signal are also input to the three-phase short drive signal control logic 304, so that a three-phase short signal, an overvoltage detection signal and a ground fault detection signal are simultaneously generated by the host microcomputer. Prevention becomes possible.
　以上に説明した地絡検出装置１０９及び保護ロジック回路１０８を用いた電力変換装置の「通常時の動作」と「地絡発生時の動作」の概略について以下に説明する。 An outline of the “normal operation” and “operation when a ground fault occurs” of the power converter using the ground fault detection device 109 and the protection logic circuit 108 described above will be described below.
　通常動作時はインバータ回路部１０３から三相誘導電動機１０４へ交流電流が出力されるが、このときの電流センサ１０７の出力電圧は２．５Ｖを中心とした正弦波となっている。インバータから三相誘導電動機への出力電流はＵ相、Ｖ相及びＷ相で１２０度ずれているため、Ｕ相、Ｖ相及びＷ相の電流センサ１０７の出力電圧も位相が１２０度ずつずれている。 During normal operation, an alternating current is output from the inverter circuit unit 103 to the three-phase induction motor 104. At this time, the output voltage of the current sensor 107 is a sine wave centered at 2.5V. Since the output current from the inverter to the three-phase induction motor is shifted by 120 degrees in the U phase, V phase, and W phase, the output voltage of the current sensor 107 in the U phase, V phase, and W phase is also shifted by 120 degrees. Yes.
　よって、Ｕ相、Ｖ相及びＷ相の電流センサの出力をスター結線した抵抗負荷１１２、１１３、１１４に繋ぐとスター結線の中性点電位は略２．５Ｖで安定する。本実施例では判定器２０１の閾値を３Ｖ、判定器２０２の閾値を２Ｖとしているので地絡検出信号は出力されず、保護ロジック回路１０８の各バッファ３０１、３０２a、３０２b及び３０３は導通状態となり、電動機制御マイクロコンピュータ１１０からのＰＷＭ信号はそのままゲート駆動部１０６へ送られ三相誘導電動機１０４を正常に駆動する。 Therefore, when the outputs of the U-phase, V-phase, and W-phase current sensors are connected to the resistance loads 112, 113, and 114 connected in a star connection, the neutral point potential of the star connection is stabilized at about 2.5V. In this embodiment, since the threshold value of the determiner 201 is 3V and the threshold value of the determiner 202 is 2V, the ground fault detection signal is not output, and the buffers 301, 302a, 302b, and 303 of the protection logic circuit 108 are in a conductive state. The PWM signal from the motor control microcomputer 110 is sent to the gate drive unit 106 as it is to drive the three-phase induction motor 104 normally.
　一方、地絡現象が発生すると、インバータ回路部１０３からの出力電流は地絡地点から漏れて乱れることになる。インバータ回路部１０３の出力電流が乱れたことにより、電流センサ１０７の出力電圧も正弦波から乱れて電流センサ１０７とスター結線された抵抗負荷の中性点１１５の電位は２．５Ｖから変動する。この変動した中性点１１５の電位が判定器２０１の上側閾値である３Ｖを越える、または判定器２０２の下側閾値である２Ｖを下回ると地絡検出信号が出力される。 On the other hand, when a ground fault occurs, the output current from the inverter circuit unit 103 leaks from the ground fault point and is disturbed. When the output current of the inverter circuit unit 103 is disturbed, the output voltage of the current sensor 107 is also disturbed from the sine wave, and the potential of the neutral point 115 of the resistance load star-connected to the current sensor 107 varies from 2.5V. When the potential of the fluctuating neutral point 115 exceeds 3V, which is the upper threshold value of the determiner 201, or falls below 2V, which is the lower threshold value of the determiner 202, a ground fault detection signal is output.
　このような地絡検出装置１０９によって地絡現象が検出されると、保護ロジック回路１０８は次のような動作を行なうことになる。 When a ground fault phenomenon is detected by such a ground fault detection device 109, the protection logic circuit 108 performs the following operation.
　３相オープン動作の場合、図３に示したように、地絡検出信号３０６は保護ロジック回路１０８のタイマ回路３０５を経由しバッファ３０１に入力される。３相オープン時の動作は上述した通りで、スイッチング素子３ａ～３ｆの全てをＯＦＦ状態とする。３相オープン状態ではスイッチング素子３ａ～３ｆの全てをＯＦＦにしているため、三相誘導電動機１０４へ電流が供給されずに地絡電流が流れることがないようになる。 In the case of the three-phase open operation, the ground fault detection signal 306 is input to the buffer 301 via the timer circuit 305 of the protection logic circuit 108 as shown in FIG. The operation when the three phases are open is as described above, and all the switching elements 3a to 3f are turned off. In the three-phase open state, all of the switching elements 3a to 3f are turned off, so that no current is supplied to the three-phase induction motor 104 and no ground fault current flows.
　一方、３相ショート動作の場合、図４に示したように、地絡検出信号３０６は保護ロジック回路１０８のタイマ回路３０５を経由しバッファ３０１と、３相ショート駆動信号制御ロジック３０４の両方に入力される。 On the other hand, in the case of a three-phase short operation, as shown in FIG. 4, the ground fault detection signal 306 is input to both the buffer 301 and the three-phase short drive signal control logic 304 via the timer circuit 305 of the protection logic circuit 108. Is done.
　３相ショート時の動作は上述した通りで、スイッチング素子３ａ～３ｃをＯＮして残りをＯＦＦする上アーム３相ショート状態か、スイッチング素子３ｄ～３ｆをＯＮして残りをＯＦＦする下アーム３相ショート状態にする。 The operation at the time of three-phase short is as described above. The upper arm three-phase short state in which switching elements 3a to 3c are turned on and the rest is turned off, or the lower arm three phases in which switching elements 3d to 3f are turned on and the rest are turned off. Short circuit.
　このようにすることで、３相ショート状態では三相誘導電動機の誘起電圧によるスイッチング素子の耐圧破壊を防ぐことができる。 By doing so, it is possible to prevent breakdown of the switching element due to the induced voltage of the three-phase induction motor in the three-phase short circuit state.
　また、地絡現象が発生している状態では誘起電圧が地絡地点の電位を中心に正側と負側の上下方向で発生することになる。このとき発生した誘起電圧が直流電源の電位を上回るとスイッチング素子の還流ダイオードを経由して予期せぬ電流がインバータ回路部１０３や平滑コンデンサ１０２、直流電源１０１へ流れ込んでしまい、これらを破壊する可能性がある。 In addition, in the state where the ground fault occurs, an induced voltage is generated in the vertical direction on the positive side and the negative side around the potential at the ground fault point. If the induced voltage generated at this time exceeds the potential of the DC power supply, an unexpected current flows into the inverter circuit unit 103, the smoothing capacitor 102, and the DC power supply 101 via the freewheeling diode of the switching element, and these can be destroyed. There is sex.
　これに対して、３相ショート動作ではスイッチング素子３ａ～３ｃ、またはスイッチング素子３ｄ～３ｆをＯＮにし、他のスイッチング素子をＯＦＦするため、三相誘導電動機１０４とＯＮ状態のスイッチング素子間で電流が還流させることができ、還流ダイオードを経由した電流の流入を防ぐことができる。 On the other hand, in the three-phase short operation, the switching elements 3a to 3c or the switching elements 3d to 3f are turned on and the other switching elements are turned off, so that a current flows between the three-phase induction motor 104 and the switching element in the ON state. It is possible to recirculate, and it is possible to prevent inflow of current via the freewheeling diode.
　本実施例の電流センサ１０７はホール素子による絶縁された電流センサを用いており、これにより直流電源１０１の電圧から絶縁されるようになるので、弱電系（５Ｖ等）の電源で地絡検出部１０９を構成することができ、小型、低コスト化が可能となる。 The current sensor 107 of this embodiment uses a current sensor that is insulated by a Hall element, and is thereby insulated from the voltage of the DC power supply 101. Therefore, a ground fault detection unit is used with a weak power system (5V, etc.) power supply. 109 can be configured, and the size and cost can be reduced.
　また、地絡検出部１０９の抵抗１１２、抵抗１１３、抵抗１１４をネットワーク抵抗で構成すれば、抵抗１１２、抵抗１１３、抵抗１１４の抵抗値の相対誤差を小さくすることでスター結線された抵抗負荷の中性点１１５の電位のばらつきを抑えることができ、より高精度に地絡現象を検出することができる。 In addition, if the resistors 112, 113, and 114 of the ground fault detection unit 109 are configured by network resistors, the relative error of the resistance values of the resistors 112, 113, and 114 can be reduced to reduce the resistance of the star-connected resistance load. Variation in the potential of the neutral point 115 can be suppressed, and the ground fault phenomenon can be detected with higher accuracy.
　尚、ゲート駆動部１０６に地絡検出部１０９と保護動作を行う保護ロジック回路１０８を作りこむように構成しても良いが、電流センサ１０７の出力は導電動機駆動制御部１０５に入力されるためゲート駆動部１０６へ電流センサ１０７の信号を送る信号線を増やす必要があり、また、ゲート駆動部１０６は弱電系の電源でないため高耐圧化させる必要があり回路構成が高コストとなる課題を有しているので好ましいものではない。 Note that the ground drive detection unit 109 and the protection logic circuit 108 that performs the protection operation may be built in the gate drive unit 106. However, since the output of the current sensor 107 is input to the conductive motive drive control unit 105, the gate There is a need to increase the number of signal lines for sending signals from the current sensor 107 to the drive unit 106. Also, since the gate drive unit 106 is not a weak power source, it is necessary to increase the withstand voltage, and the circuit configuration is expensive. Therefore, it is not preferable.
　これに対して、本発明では、電流センサ１０７の出力は電動機駆動制御部１０５に入力されるため信号線を増やす必要がなく、また、電動機駆動制御部１０５は弱電系の電源であるので高耐圧化させる必要がないものである。 On the other hand, in the present invention, since the output of the current sensor 107 is input to the motor drive control unit 105, there is no need to increase the number of signal lines, and since the motor drive control unit 105 is a low power system power source, It is not necessary to make it.
　更に、地絡検出部１０９と保護ロジック回路１０８の電源を別系統で構成し、地絡検出信号をＨｉｇｈレベルの電圧信号とすることで地絡検出部１０９の電源が故障等により落ちたときでも、保護ロジック回路１０８が誤動作しないようにできる、という効果も期待できる。 Further, even when the power supply of the ground fault detection unit 109 and the protection logic circuit 108 are configured in different systems and the ground fault detection signal is a high level voltage signal, the power supply of the ground fault detection unit 109 is dropped due to a failure or the like. The effect that the protection logic circuit 108 can be prevented from malfunctioning can also be expected.
　従来の交流電流の地絡現象の検出は電流センサの情報を元にマイクロコンピュータのソフトウエア処理により行っていたので、マイクロコンピュータの異常や電流センサの情報を読み取るサンプリングのタイミングによっては地絡現象を検出できない状況が発生したり、交流電流の地絡が発生してから保護回路による保護動作へ移るまでの動作時間がマイクロコンピュータの処理速度や処理タスクの起動周期に依存しているので地絡現象に対する保護動作が間に合わない状況も発生するといった課題があった。 Conventional detection of the ground fault phenomenon of alternating current has been performed by microcomputer software processing based on the current sensor information, so depending on the abnormality of the microcomputer and the sampling timing for reading the current sensor information, the ground fault phenomenon may be detected. The grounding phenomenon occurs because the operation time from the occurrence of an undetectable situation or the occurrence of an alternating current ground fault to the protection operation by the protection circuit depends on the processing speed of the microcomputer and the start cycle of the processing task. There is a problem that a situation occurs in which the protection operation against the time is not in time.
　また、三相誘導電動機の負荷側に地絡検出回路を設けると、各相の抵抗を負荷側と直接接続するので検出回路の高耐圧化が要求され、このため地絡検出回路が大型、高コスト化するという課題があった。 In addition, if a ground fault detection circuit is provided on the load side of the three-phase induction motor, the resistance of each phase is directly connected to the load side, so a high withstand voltage of the detection circuit is required. There was a problem of cost.
　これに対して、本発明では、インバータ回路部と電動機のような負荷の間を結ぶＵ相、Ｖ相及びＷ相の各出力線を流れる交流電流の電流値を検出する電流センサの出力部をスター結線した抵抗負荷に接続し、スター結線した抵抗負荷の中性点の出力を判定器に入力して地絡現象を検出し、この地絡現象の検出によってインバータ回路を駆動するゲート駆動回路の動作を制限する保護ロジック回路を動作させるようにしたので、確実に地絡現象をすることができ、しかも電流センサから抵抗負荷に電流を供給するので弱電系の回路構成とでき地絡検出装置に高耐圧化の対応を考慮しなくてよくなるものである。 On the other hand, in the present invention, the output part of the current sensor that detects the current value of the alternating current flowing through the U-phase, V-phase, and W-phase output lines connecting between the inverter circuit part and the load such as the electric motor is provided. Connect to a star-connected resistive load, and input the neutral point output of the star-connected resistive load to the determiner to detect the ground fault phenomenon. By detecting this ground fault phenomenon, the gate drive circuit that drives the inverter circuit Since the protection logic circuit that restricts the operation is operated, it is possible to reliably cause a ground fault phenomenon and to supply a current from the current sensor to the resistive load. This makes it unnecessary to consider the countermeasures for increasing the breakdown voltage.
　１０１…直流電源、１０２…平滑コンデンサ、１０３…インバータ回路部、１０４…三相誘導電動機、１０５…電動機駆動制御部、１０６…ゲート駆動部、１０７…電流センサ、１０８…保護ロジック回路、１０９…地絡検出部、１１０…電動機制御マイクロコンピュータ、１１１…出力線、１１２，１１３，１１４…抵抗負荷、１１５…中性点、１１６…判定器、２０１…上側閾値判定器、２０２…下側閾値判定器、２０３，２０４，２０７、２１０、２１１、２１２…抵抗、２０５、２０９…比較器、３０１、３０２a、３０２ｂ、３０３…バッファ。 DESCRIPTION OF SYMBOLS 101 ... DC power supply, 102 ... Smoothing capacitor, 103 ... Inverter circuit part, 104 ... Three-phase induction motor, 105 ... Electric motor drive control part, 106 ... Gate drive part, 107 ... Current sensor, 108 ... Protection logic circuit, 109 ... Ground Fault detection unit, 110 ... electric motor control microcomputer, 111 ... output line, 112, 113, 114 ... resistance load, 115 ... neutral point, 116 ... judgment device, 201 ... upper threshold judgment device, 202 ... lower threshold judgment device , 203, 204, 207, 210, 211, 212 ... resistors, 205, 209 ... comparators, 301, 302a, 302b, 303 ... buffers.

Claims (6)

  1. 電動機を駆動するための交流電流を生成するインバータ回路部と、このインバータ回路部を構成する半導体スイッチング素子を制御するゲート駆動部を少なくとも備えた電力変換装置において、
    前記電動機と前記インバータ回路部との間を結ぶＵ相、Ｖ相及びＷ相の各出力線を流れる電流を検出する電流センサの出力部をスター結線した抵抗負荷に接続し、前記スター結線した抵抗負荷の中性点の出力を判定器に入力して前記出力の変化から地絡現象を検出し、この地絡現象を検出すると前記ゲート駆動部の動作を制限する保護ロジック回路を動作させることを特徴とする電力変換装置。     In a power conversion device including at least an inverter circuit unit that generates an alternating current for driving an electric motor and a gate driving unit that controls a semiconductor switching element that constitutes the inverter circuit unit.
    An output part of a current sensor that detects currents flowing through U-phase, V-phase, and W-phase output lines connecting the electric motor and the inverter circuit section is connected to a star-connected resistance load, and the star-connected resistance The output of the neutral point of the load is input to the determination device, a ground fault phenomenon is detected from the change in the output, and when this ground fault phenomenon is detected, a protection logic circuit that restricts the operation of the gate drive unit is operated. A power conversion device.
  2. 請求項１に記載の電力変換装置において、
    前記電流センサは前記出力線を流れる電流を弱電系で使用される電圧に変換し、この弱電系に変換された電圧は前記ゲート駆動回路を制御する電動機制御マイクロコンピュータと前記スター結線した抵抗負荷に入力されることを特徴とする電力変換装置。     The power conversion device according to claim 1,
    The current sensor converts the current flowing through the output line into a voltage used in a weak electrical system, and the voltage converted into the weak electrical system is applied to the motor control microcomputer that controls the gate drive circuit and the resistance load that is star-connected. A power converter characterized by being input.
  3. 請求項１に記載の電力変換装置において、
    前記スター結線した抵抗負荷の中性点の出力は電圧として検出され、この中性点の電圧は電圧比較器に入力されて所定の比較電圧と比較されて地絡現象が検出されることを特徴とする電力変換装置。     The power conversion device according to claim 1,
    The neutral point output of the star-connected resistance load is detected as a voltage, and the neutral point voltage is input to a voltage comparator and compared with a predetermined comparison voltage to detect a ground fault phenomenon. A power converter.
  4. 請求項３に記載の電力変換装置において、
    前記電圧比較器は第１の電圧比較器及び第２の電圧比較器から構成されており、前記第１の電圧比較器で所定の第１の比較電圧と前記中性点の電位が比較されてこれを超えると地絡現象が検出され、前記第２の電圧比較器で所定の第２の比較電圧と前記中性点の電位が比較されてこれを下回ると地絡現象が検出されることを特徴とする電力変換装置。     The power conversion device according to claim 3,
    The voltage comparator includes a first voltage comparator and a second voltage comparator, and the first voltage comparator compares a predetermined first comparison voltage with the neutral point potential. When this value is exceeded, a ground fault phenomenon is detected, and when the second voltage comparator compares the predetermined second comparison voltage with the potential at the neutral point, the ground fault phenomenon is detected. A power conversion device.
  5. 請求項１に記載の電力変換装置において、
    前記保護ロジック回路は前記ゲート駆動部と前記電動機制御マイクロコンピュータとの間に設けられ、更に前記保護ロジック回路は前記判定器によって地絡現象が検出されると前記電動機制御マイクロコンピュータからの制御信号を前記ゲート駆動部に伝えるのを遮断する遮断機能部を備えていることを特徴とする電力変換装置。     The power conversion device according to claim 1,
    The protection logic circuit is provided between the gate drive unit and the motor control microcomputer, and the protection logic circuit receives a control signal from the motor control microcomputer when a ground fault is detected by the determiner. A power conversion device comprising a shut-off function unit that shuts off transmission to the gate drive unit.
  6. 請求項５に記載の電力変換装置において、
    前記保護ロジック回路の遮断機能部は前記インバータ回路部にあるスイッチング素子の全てに繋がる制御信号ライン上に設けられた第１及び第２のバッファと、前記第１及び前記第２のバッファの間で前記制御信号ラインの半分の制御信号ライン上に設けられた第３のバッファと、前記第１及び前記第２のバッファの間で前記制御信号ラインの残りの半分の制御信号ライン上に設けられた第４のバッファとから構成され、前記第１のバッファ、前記第３のバッファ及び前記第４のバッファに前記判定器の地絡検出信号が入力されることを特徴とする電力変換装置。     The power conversion device according to claim 5,
    The cutoff function part of the protection logic circuit is between the first and second buffers provided on the control signal line connected to all the switching elements in the inverter circuit part, and the first and second buffers. A third buffer provided on a control signal line half of the control signal line, and a control signal line on the other half of the control signal line between the first and second buffers; A power converter comprising: a fourth buffer, wherein a ground fault detection signal of the determiner is input to the first buffer, the third buffer, and the fourth buffer.
PCT/JP2012/079056 2011-12-20 2012-11-09 Power conversion device WO2013094330A1 (en)

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