JP2013099187A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion device capable of identifying a fault location of a circuit included in the power conversion device.SOLUTION: A power conversion device includes: switching elements Q1 to Q6 that are connected between power-supply lines P and N connected to both positive and negative terminals of a power supply; diodes D1 to D6 that are connected in parallel to the switching elements Q1 to Q6 in a reverse direction of a current flowing during forward conduction of the switching elements Q1 to Q6; a plurality of current detection means that are connected closer to the switching elements side than to connection points between low-potential side terminals of the switching elements Q1 to Q6 and anode terminals of the diodes D1 to D6 and detect currents; and fault detection means that detects faults of the switching elements Q1 to Q6 on the basis of the detection currents detected by the current detection means.

Description

  The present invention relates to a power conversion device.

  Using the switching elements provided in each phase, a voltage is applied to each phase of the motor so that current flows in each phase of the motor to drive the motor, and each switching element in each phase of the inverter is connected in series. A test pattern indicating a predetermined combination of turning on the switching element of the inverter and the arranged current detector is stored, and the current detection value of each phase detected by the current detector as a response to the test pattern and the test pattern And a short-circuit location identifying means for identifying a short-circuit fault location based on the above-mentioned one, turning on one of the switching elements on the upper side or the lower side of each phase of the inverter and turning off the other switching elements When the current detection value connected in series to the ground side of the lower switching element is larger than the value indicating overcurrent, It said other switching element fails, that determines that there has been known (Patent Document 1).

International Publication No. 2008/129658

  However, even when a diode connected to the switching element is short-circuited, there is a problem that it is determined that the switching element is defective.

  The present invention provides a power conversion device that can identify a failure location of a circuit included in the power conversion device.

  The present invention solves the above problems by providing a current detection means for detecting a current connected to the switching element side of the connection point between the low potential side terminal of the switching element and the anode terminal of the diode.

  According to the present invention, since the detection current of the current detection unit changes depending on whether or not the switching element has failed, there is an effect that it is possible to specify a failure location of a circuit included in the power conversion device.

1 is a block diagram of a motor control system including a power conversion device according to an embodiment of the present invention. It is a circuit diagram which shows the circuit of the U phase of the inverter of FIG. It is a circuit diagram of the motor control system of FIG. It is a flowchart which shows the control procedure of the power converter device of FIG. It is a flowchart which shows the control procedure of the failure detection in an upper arm circuit among the control procedures of the power converter device of FIG. It is a flowchart which shows the control procedure of the failure detection in a lower arm circuit among the control procedures of the power converter device of FIG. It is a block diagram of the motor control system containing the power converter device which concerns on the modification of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<< First Embodiment >>
FIG. 1 is a block diagram showing a motor control system including a power converter according to an embodiment of the present invention. Although not shown in detail, the electric vehicle of this example is a vehicle that travels using a three-phase AC power permanent magnet motor 102 as a travel drive source, and the motor 102 is coupled to the axle of the electric vehicle. Hereinafter, although an electric vehicle will be described as an example, the present invention can be applied to a hybrid vehicle (HEV), and can also be applied to a power conversion device of a device other than a vehicle.

  The motor drive system of this example includes the above-described three-phase AC motor 102, a battery 101 that is a power source of the motor 102, and an inverter 100 that converts DC power of the battery 101 into AC power. The circuit of the inverter 100 is connected by a bus bar, and the connection between the battery 101 and the inverter 100 and the connection between the inverter 100 and the motor 102 are connected by, for example, a high-voltage harness.

  The battery 101 is a direct current power source and is connected to the inverter 100. The battery 101 is mounted with a secondary battery such as a lithium ion battery. A relay (not shown) is connected between the battery 101 and the inverter 100, and the relay is driven in conjunction with an ON / OFF operation of a key switch (not shown) of the vehicle. Note that the motor 102 also functions as a generator, and AC power generated by the motor 102 is converted to DC by the inverter 100 and input to the battery 101, and the battery 101 is charged.

  The inverter 100 includes upper arm circuits 10, 30, 50, lower arm circuits 20, 40, 60, a smoothing capacitor 71, a discharge resistor 72, a drive circuit 80, and a control unit 90. 101 direct current power is converted into alternating current power and supplied to the motor 102. The upper arm circuits 10, 30, and 50 are circuits in which switching elements Q1, Q3, and Q5 and diodes D1, D3, and D5 are respectively connected in parallel, and the lower arm circuits 20, 40, and 60 are switching elements Q2, Q4, respectively. , Q6 and diodes D2, D4, D6 correspondingly connected in parallel. In this example, three pairs of circuits in which two switching elements Q1 to Q6 are connected in series are connected between the power supply line P and the power supply line N, so that they are connected in parallel to the battery 101. Each connection point for connecting the switching elements and the three-phase input portion of the motor 102 are electrically connected to each other. For example, an insulated gate bipolar transistor (IGBT) or a MOSFET is used for each of the switching elements Q1 to Q6. For each of the diodes D1 to D6, for example, FRD (Fast Recovery Diode) is used, and in the following, IGBTs are used as the switching elements Q1 to Q6 in this example.

  In the example shown in FIG. 1, switching elements Q1 and Q2, switching elements Q3 and Q4, switching elements Q5 and Q6 are connected in series, and are connected between the switching elements Q1 and Q2 and the U phase of the motor 4. The V phase of the motor 4 is connected between the switching elements Q3 and Q4, and the W phase of the motor 4 is connected between the switching elements Q5 and Q6. Each switching element Q1-Q6 is controlled by the control part 90, and is switched by a high frequency.

  The collector terminal of the switching element Q1 is connected to the cathode terminal of the diode D1, and the emitter terminal of the switching element Q1 is connected to the anode terminal of the diode D1. The gate terminal of the switching element Q1 is connected to the drive circuit 80. Similarly, the terminals of the other switching elements Q2 to Q6 are connected to the terminals of the diodes D2 to D6 and the controller 108. Each diode D1-D6 is connected in the reverse direction with respect to the forward direction of each switching element Q1-Q6.

  The upper arm circuits 10, 30, 50 have current sensors 11, 31, 51 for detecting the emitter currents of the switching elements Q1, Q3, Q5, and a collector current of the switching elements Q1, Q3, Q5. Current sensors 12, 32, 52 are provided. The lower arm circuits 20, 40, 60 are provided with current sensors 21, 41, 61 for connecting the emitter currents of the switching elements Q2, Q4, Q6. A voltage sensor 73 for measuring an intermediate potential between the power supply line P and the power supply line N is connected between the upper arm circuit 10 and the lower arm circuit 20.

  The current sensors 11, 12, 21, 31, 32, 41, 51, 52, 61 detect current using, for example, a shunt resistor, a Hall effect element, an on-chip sensor, or the like. The voltage sensor 73 detects a voltage by connecting a wire having a high resistance value, for example, a thin diameter, to the bus bar, or detects a voltage using a four-terminal method, a four-terminal pair method, or the like.

  Here, the connection of the current sensors 11, 12, 21 and the voltage sensor 73 will be described with reference to FIGS. FIG. 2 is a circuit diagram showing a circuit of a U-phase portion in the circuit of inverter 100 shown in FIG. The connection of the current sensors 31, 32, 41 in the upper arm circuit 30 and the lower arm circuit 40 and the connection of the current sensors 51, 52, 61 in the upper arm circuit 50 and the lower arm circuit 60 are the upper arm circuit. 10. Since this is the same as the connection of the current sensors 11, 12, 21 in the lower arm circuit 20, the description thereof is omitted.

  As shown in FIG. 2, the current sensor 11 is connected to the switching element Q1 side from the connection point between the emitter terminal of the switching element Q1 and the anode terminal of the diode D1, and detects the current flowing through the emitter terminal of the switching element Q1. . In other words, the connection point between the current sensor 11 and the switching element Q1 is closer to the switching element Q1 than the connection point between the emitter terminal of the switching element Q1 and the anode terminal of the diode D1. When the emitter terminal of the switching element Q1 and the connection terminal of the current sensor 11 are connected, the connection point between the emitter terminal of the switching element Q1 and the connection terminal of the current sensor 11 is the switching element Q1 and the switching element Q2. It suffices to be on the switching element Q1 side from the connection point between the connection line between the two and the anode terminal of the diode D1.

  The current sensor 12 is connected between the power supply line P and a connection point between the collector terminal of the switching element Q1 and the cathode terminal of the diode D1, and between the power supply line P and the collector terminal of the switching element Q1 and the cathode terminal of the diode D1. The current flowing between them is detected.

  The current sensor 21 is connected to the switching element Q2 side from the connection point between the emitter terminal of the switching element Q2 and the anode terminal of the diode D2, and detects a current flowing through the emitter terminal of the switching element Q2. In other words, the connection point between the current sensor 21 and the switching element Q2 is closer to the switching element Q2 than the connection point between the emitter terminal of the switching element Q2 and the anode terminal of the diode D2. When the emitter terminal of the switching element Q2 and the connection terminal of the current sensor 21 are connected, the connection point between the emitter terminal of the switching element Q2 and the connection terminal of the current sensor 21 is the switching element Q2 and the power supply line N. It suffices to be on the switching element Q2 side from the connection point between the connection line between the two and the anode terminal of the diode D2.

  The voltage sensor 73 is connected between a connection point between the series circuit of the upper arm circuit 10 and the lower arm circuit 20 and the U-phase input portion of the motor 102, and a connection point between the collector terminal of the switching element Q2 and the node terminal of the diode D2. It is connected and detects the potential at the connection point between the upper arm circuit 10 and the lower arm circuit 20 and the three-phase input portion of the motor 102.

  Thus, in this example, the current sensors 11, 12 are connected to the switching element Q1 and the diode D1, and the current sensor 21, the switching element Q2, and the diode D2 are connected to each other, and the current sensors 31, 32 and the switching element are connected. Q3 is associated with the diode D3, the current sensor 41 is associated with the switching element Q4 and the diode D4, the current sensors 51 and 52 are associated with the switching element Q5 and the diode D5, and the current sensor 61 is associated with the switching element Q6 and the diode D6. Connect with the corresponding.

  Returning to FIG. 1, the drive circuit 80 transmits the drive signal to the gate terminals of the switching elements Q1 to Q6 based on the switching signal generated by the control unit 90, thereby turning on and off the switching elements Q1 to Q6. It is a drive circuit for switching off.

  The control unit 90 detects an externally input torque command, a detected value of a rotor position sensor (not shown) provided in the motor 102, and a phase current of each phase of the motor 102 based on an accelerator operation by the user. The detection current of a current sensor (not shown) to be detected and the detection voltage of a voltage sensor (not shown) to detect the voltage of the battery 101 are read, and the switching signal (PWM) is set so that the output torque from the motor 102 matches the torque command. Signal) is generated and transmitted to the drive circuit 80.

  In addition, the control unit 90 specifies a failure location in the circuit of the inverter 100 based on the detection values of the current sensors 11, 12, 21, 31, 32, 41, 51, 52, 61 and the detection value of the voltage sensor 73.

  Next, control for detecting a faulty part of the circuit among the control contents of the control unit 90 will be described with reference to FIGS. 1 and 3. Here, as shown in FIG. 3, since the current sensor 11 is a sensor that detects the emitter current of the switching element Q1 on the P side (positive side) in the U phase, the detected current of the current sensor 11 is Ispe (u ), The detection current of the current sensor 12 is referred to as Ispc (u), and the detection current of the current sensor 21 is Isne (u) 21. For the V phase and the W phase, the detected current of the current sensor 31 is Ispe (v) 31, the detected current of the current sensor 32 is Ispc (v), the detected current of the current sensor 41 is Isne (v), and the current sensor The detected current 51 is referred to as Ispe (w), the detected current of the current sensor 52 is Ispc (w), and the detected current of the current sensor 61 is Isne (w). Further, the detection voltage of the voltage sensor 73 is set to Vsnc. FIG. 3 is a circuit diagram of the motor control system of this example, and is attached to each detection current of the current sensors 11, 12, 21, 31, 32, 41, 51, 52, 61 and a detection voltage of the voltage sensor 72. It is a figure for demonstrating the symbol.

  First, the motor control system of this example is started by electrically connecting a weak electric system control circuit, and a relay switch (not shown) between the inverter 100 and the battery 101 is turned on, whereby the inverter 100 and the battery are turned on. Before conducting the motor 101 and controlling the motor 102 (that is, in a state where all of the switching elements Q1 to Q6 are turned off), the following failure point detection control is started.

  The control unit 90 uses the detected voltage (Vsnc) of the voltage sensor 73 to identify the failure points of the switching elements Q1 to Q6 and the diodes D1 to D6, and the upper arm circuits 10, 30, 50 and the lower arm circuit 20 , 40 and 60, it is determined whether or not a short-circuit fault has occurred.

  The control unit 90 includes a threshold voltage (Vpn) indicating that a failure has occurred in the upper arm circuits 10, 30 and 50 and a threshold voltage (0) indicating that a failure has occurred in the lower arm circuits 20, 40 and 60. (V)) is preset. For example, when a short circuit failure has occurred in the switching element Q1 or the diode D1, there is a gap between the connection point between the upper arm circuit 10 and the power supply line P and the connection point between the upper arm circuit 10 and the lower arm circuit 20. In order to short-circuit, Vsnc detects a high voltage (Vpn) that is the voltage of the battery 101. Similarly, when the switching element Q3 or the diode D3 included in the upper arm circuit 30 is short-circuited or when the switching element Q5 or the diode D5 included in the upper arm circuit 50 is short-circuited, Alternatively, it is short-circuited in the upper arm circuit 50 and is conducted to the connection point of the voltage sensor 73 via the U-phase connection line of the motor 102. Therefore, Vsnc detects a high voltage (Vpn) that is the voltage of the battery 101. That is, the control unit 90 determines that a failure has occurred in the upper arm circuits 10, 30, and 50 when Vsnc is Vpn.

  Further, for example, when a short circuit failure has occurred in the switching element Q2 or the diode D2, Vsnc is a battery because a short circuit is caused from the positive side of the lower arm circuit 20 to the connection point between the lower arm circuit 20 and the power supply line N. 0 (V) which is the potential on the negative electrode side of 101 is detected. Similarly, when the switching element Q4 or the diode D4 included in the lower arm circuit 40 is short-circuited or when the switching element Q6 or the diode D6 included in the lower arm circuit 60 is short-circuited, Alternatively, it is short-circuited in the lower arm circuit 60 and is conducted from the power supply line N to the connection point of the voltage sensor 73 via the U-phase connection line of the motor 102. Therefore, Vsnc detects 0 (V). That is, the control unit 90 determines that a failure has occurred in the lower arm circuits 20, 40, 60 when Vsnc is 0 (V).

  When the control unit 90 specifies that a short circuit failure has occurred in any of the upper arm circuits 10, 30, 50 and the lower arm circuits 20, 40, 60, the upper arm circuits 10, 30, 50 have failed. In this case, based on Ispc (u), Ispc (v), Ispc (w), Ispe (u), Ispe (v) and Ispe (w), switching elements Q1, Q3, Q5 and diodes D1, D3, It is determined which element of D5 has a short-circuit fault, and when the lower arm circuits 10, 30, 50 are faulty, Ispc (u), Ispc (v), Ispc (w), Isne (u ), Isne (v) and Isne (w), it is specified which element of the switching elements Q2, Q4, Q6 and the diodes D2, D4, D6 has a short-circuit fault.

  The failure point detection control in the upper arm circuits 10, 30, and 50 will be described. When the control unit 90 detects that the upper arm circuit 10, 30, or 50 has failed, it applies a detection pulse to the gate terminal of any one of the switching element Q2, the switching element Q4, or the switching element Q6. Thus, any of switching element Q2, switching element Q4, or switching element Q6 is turned on, and the conduction state of the elements included in the circuits of upper arm circuits 10, 30, 50 is detected. The detection pulses are input to the switching elements Q2, Q4, and Q6 from the U phase, and sequentially input to the V phase and the W phase. When the detection pulse is applied to the U-phase switching element Q2, the control unit 90 detects a short-circuit failure in the switching element Q1 and the diode D1, and inputs the detection pulse to the V-phase switching element Q4. If a detection pulse is input to the W-phase switching element Q6, a short-circuit fault in the switching element Q5 and the diode D5 is detected.

  The detection pulse is a signal for switching on and off the switching elements Q1 to Q6 in order to specify a failure location (a signal that is turned on by supplying the detection pulse to the gate terminal of the switching element and turned off by not supplying it) This is a failure detection signal for causing a current that does not destroy the switching elements Q1 to Q6 to flow through the switching elements Q1 to Q6. The ON time (supply time) of the detection pulse is set to a time that does not cause the switching elements Q1 to Q6 to generate heat by inputting a pulse to the gate terminals of the switching elements Q1 to Q6 and causing a current to flow.

  If a detection pulse is applied to the switching element Q2 when a short circuit failure has occurred in the switching element Q1, a minute current from the battery 101 passes from the power supply line P through the collector terminal and emitter terminal of the switching element Q1, and the switching element Q2 And the current sensors 11 and 12 detect the current. Therefore, the control unit 90 determines that a short-circuit failure has occurred in the switching element Q1 when Ispc (u) and Ispe (u) are not zero.

  Further, when a short circuit failure occurs in the diode D1, when a detection pulse is applied to the switching element Q2, a minute current from the battery 101 passes from the power line P through the diode D1 and enters the collector terminal of the switching element Q2. It flows through the switching element Q2 to the power line N. At this time, the current sensor 12 detects the current. However, since the current sensor 11 is connected to the emitter terminal side of the switching element Q1 from the connection point of the diode D1, the current sensor 11 does not detect the current. Therefore, the control unit 90 determines that a short-circuit fault has occurred in the diode D1 when Ispc (u) is not zero and Ispe (u) is zero.

  In addition, when a failure occurs in the switching element Q1 and the diode D1, when a detection pulse is applied to the switching element Q2, the minute current from the battery 101 is reversed with respect to the switching element Q1 in the off state and the minute current. The current sensor 11, 12 does not detect the current without flowing through the diode D1. Therefore, the control unit 90 determines that the switching element Q1 and the diode D1 are normal when Ispc (u) and Ispe (u) are zero. When a short circuit failure is not detected in the U phase, the control unit 90 shifts to another phase that is not detected and performs failure detection of the upper arm circuits 30 and 50.

  The short-circuit failure detection in the upper arm circuits 30 and 50 is the same as the detection method in the upper arm circuit 10 that is the U phase, and the control unit 90 applies a detection pulse to the switching element Q4, and Ispc (v) and Ispe If (v) is not zero, it is determined that a short circuit failure has occurred in the switching element Q3. If Ispc (v) is not zero and Ispe (v) is zero, a short circuit occurs in the diode D3. When it is determined that a failure has occurred and Ispc (v) and Ispe (v) are zero, it is determined that the switching element Q3 and the diode D3 are normal.

  Further, the control unit 90 applies a detection pulse to the switching element Q6, and determines that a short-circuit failure has occurred in the switching element Q5 when Ispc (w) and Ispe (w) are not zero, and Ispc (w) Is not zero and Ispe (w) is zero, it is determined that a short-circuit fault has occurred in the diode D5. If Ispc (w) and Ispe (w) are zero, switching is performed. It is determined that the element Q5 and the diode D5 are normal. Thereby, the control part 90 specifies the failure location of switching element Q1, Q3, Q5 and diode D1, D3, D5 based on the detected current of the current sensors 11, 12, 31, 32, 51, 52.

  Next, failure point detection control in the lower arm circuits 20, 40, 60 will be described. When it is detected that the lower arm circuit 20, 40, 60 is malfunctioning, a detection pulse is applied to the gate terminal of any one of the switching element Q1, the switching element Q3, or the switching element Q5, and the lower arm circuit The conduction state of the switching elements Q2, Q4, Q6 included in the circuit of 20, 40, 60 is detected, and a detection pulse is applied to the gate terminal of any one of the switching element Q2, the switching element Q4, or the switching element Q6. Thus, the conduction states of the diodes D2, D4, D6 included in the circuits of the lower arm circuits 20, 40, 60 are detected. The detection pulse input to the switching elements Q1, Q3, and Q5 and the detection pulse input to the switching elements Q2, Q4, and Q6 start in the U phase, and are sequentially input to the V phase and the W phase.

  When the detection pulse is applied to the switching element Q1, the control unit 90 detects a short-circuit failure of the switching element Q2, and when the detection pulse is applied to the switching element Q2, the control unit 90 detects a short-circuit failure of the diode D2. Is detected. Further, the control unit 90 detects the short-circuit failure of the switching element Q4 and the switching element Q6 when the detection pulse is applied to the switching element Q3 and the switching element Q5, respectively, and detects each of the switching element Q4 and the switching element Q6. When a pulse is applied, a short circuit failure of the diode D4 and the diode D6 is detected.

  If a detection pulse is applied to the switching element Q1 when a short circuit failure has occurred in the switching element Q2, a minute current from the battery 101 flows from the power line P to the power line N through the switching element Q1 and the switching element Q2. The current sensor 21 detects the current. Therefore, the control unit 90 determines that a short circuit failure has occurred in the switching element Q2 when Isne (u) is not zero. On the other hand, when Isne (u) is zero, the control unit 90 determines that the switching element Q2 is normal, and detects the failure of the lower arm circuits 40 and 60 in other phases that are not detected, or The process proceeds to failure detection of the diode D2.

  When a short circuit failure occurs in the diode D2, when the switching element Q2 is turned on from the state in which the return current flows from the motor 102 to the diode D1 by applying a detection pulse to the switching element Q2, the diode D2 is a freewheeling diode. The current flowing in the forward direction of the diode D1 flows out in the reverse direction as the recovery current, flows to the connection point between the power supply line N and the lower arm circuit 20 through the shorted diode D2, and the current sensor 12 The recovery current is detected. Therefore, the control unit 90 determines that a short-circuit failure has occurred in the diode D2 when Ispc (u) is not zero. On the other hand, if Ispc (u) is zero, the control unit 90 determines that the diode D2 is normal, and proceeds to failure detection of the lower arm circuits 40 and 60 of other phases that are not detected. Alternatively, when failure detection of the switching element Q2 is not performed, the process proceeds to failure detection of the switching element Q2.

  The short-circuit failure detection in the lower arm circuits 40 and 60 is the same as the detection method in the lower arm circuit 20 that is the U phase, and the control unit 90 applies a detection pulse to the switching element Q3 and Isne (v) is zero. If not, it is determined that a short-circuit fault has occurred in the switching element Q4, a detection pulse is applied to the switching element Q4, and if Ispc (v) is not zero, it is determined that a short-circuit fault has occurred in the diode D4. . Further, the control unit 90 applies a detection pulse to the switching element Q5, determines that a short-circuit failure has occurred in the switching element Q6 when Isne (w) is not zero, and applies the detection pulse to the switching element Q6. , Ispc (w) is not zero, it is determined that a short-circuit fault has occurred in the diode D6. Thereby, the control part 90 specifies the failure location of switching element Q2, Q4, Q6 and diode D2, D4, D6 based on the detection voltage of the current sensors 11, 31, 51, 22, 42, 62.

  Next, a control procedure for detecting a fault location in the control unit 90 of this example will be described with reference to FIGS. 4 is a flowchart showing a control procedure for detecting a fault location in the control unit 90, FIG. 5 is a flowchart showing a control procedure for detecting a fault location in the upper arm circuits 10, 30, and 50 in the control unit 90, and FIG. 5 is a flowchart showing a control procedure for detecting a fault location of the lower arm circuits 20, 40, 60 in the control unit 90. 5 and 6, the switching element Q1 is an IGBT on the power supply line P side in the U phase, and is therefore referred to as IGBT (UP). Similarly, the other switching elements Q2 to Q6 are also referred to as IGBT ( UN), IGBT (VP), IGBT (VN), IGBT (WP), IGBT (WN). The same applies to the diodes D1 to D6.

  In step S <b> 1, the motor control system of this example drives a low-power control circuit including the control unit 90. In step S <b> 2, control unit 90 turns on a relay switch (not shown) between battery 101 and inverter 100, thereby establishing conduction between inverter 100 and battery 101. In step S <b> 3, the control unit 90 detects the detection voltage (Vsnc) of the voltage sensor 73. In step S4, control unit 90 determines whether or not Vsnc is equal to the threshold voltage (Vpn). When Vsnc is equal to Vpn, the control proceeds to detection control of a fault location of the upper arm circuit 10, 30, 50 shown in FIG.

  On the other hand, when Vsnc is not equal to Vpn, the controller 90 determines whether or not Vsnc is equal to the threshold voltage (0 (V)) (step S5). When Vsnc is equal to 0 (V), the process proceeds to failure point detection control of the lower arm circuits 20, 40, 60 shown in FIG. On the other hand, when Vsnc is not equal to 0 (V), the control unit 90 determines that a short circuit failure has not occurred in the circuit included in the inverter 100, and ends the failure point detection control.

  Next, the control procedure of the detection control of the fault location of the upper arm circuits 10, 30, and 50 will be described with reference to FIG. In step S401, the controller 90 applies a detection pulse to the switching element Q2 via the drive circuit 80. In step S402, control unit 90 detects the detection current (Ispc (u)) of current sensor 12. In step S403, control unit 90 determines whether Ispc (u) is equal to zero. If Ispc (u) is equal to zero, the process proceeds to step S409.

  On the other hand, if Ispc (u) is not equal to zero, in step S404, the control unit 90 detects the detected current (Ispe (u)) of the current sensor 11. In step S405, control unit 90 determines whether or not Ispe (u) is equal to zero. If Ispe (u) is equal to zero, the process proceeds to step S408.

  On the other hand, if Ispe (u) is not equal to zero, the control unit 90 determines that the switching element Q1 has a short circuit failure (step S406). In step S407, the control unit 90 turns off a relay switch (not shown) between the inverter 100 and the battery 101 as fail-safe control processing, and informs the user that a short-circuit failure has occurred. Notification is performed, and the control of this example ends. In addition, when notifying the short-circuit failure, the control unit 90 may notify the identified failure location so that it can be identified.

  Returning to step S405, if Ispc (u) is equal to zero, the control unit 90 determines that the diode D1 is short-circuited (step S408), and proceeds to step S407.

  Returning to step S403, if Ispc (u) is equal to zero, in step S409, the control unit 90 applies a detection pulse to the switching element Q4 via the drive circuit 80. In step S410, control unit 90 detects the detection current (Ispc (v)) of current sensor 32. In step S411, control unit 90 determines whether Ispc (v) is equal to zero. If Ispc (v) is equal to zero, the process proceeds to step S416.

  On the other hand, if Ispc (v) is not equal to zero, the control unit 90 detects the detected current (Ispe (v)) of the current sensor 31 in step S412. In step S413, control unit 90 determines whether or not Ispe (v) is equal to zero. If Ispe (v) is equal to zero, the process proceeds to step S415.

  On the other hand, if Ispe (v) is not equal to zero, the control unit 90 determines that the switching element Q3 is short-circuited (step S414), and proceeds to step S407.

  Returning to step S413, if Ispe (v) is equal to zero, the control unit 90 determines that the diode D3 is short-circuited (step S415), and proceeds to step S407.

  Returning to step S411, if Ispc (v) is equal to zero, in step S416, the control unit 90 applies a detection pulse to the switching element Q6 via the drive circuit 80. In step S417, control unit 90 detects the detection current (Ispe (w)) of current sensor 51. In step S418, control unit 90 determines whether or not Ispe (w) is equal to zero. If Ispe (w) is equal to zero, the process proceeds to step S420.

  On the other hand, if Ispe (w) is not equal to zero, the control unit 90 determines that the switching element Q5 is short-circuited (step S419), and proceeds to step S407.

  Returning to step S418, if Ispe (w) is equal to zero, the control unit 90 determines that the diode D5 is short-circuited (step S420), and proceeds to step S407.

  Next, the control procedure of the detection control of the failure location of the lower arm circuits 20, 40, 60 will be described using FIG. In step S501, the control unit 90 applies a detection pulse to the switching element Q1 via the drive circuit 80. In step S502, the control unit 90 detects the detection current (Isne (u)) of the current sensor 21. In step S503, control unit 90 determines whether or not Isne (u) is equal to zero. If Isne (u) is equal to zero, the process proceeds to step S506.

  On the other hand, if Isne (u) is not equal to zero, the control unit 90 determines that the switching element Q2 has a short circuit failure (step S504). In step S507, the control unit 90 performs fail-safe control processing and ends the control of this example.

  Returning to step S503, if Isne (u) is equal to zero, the control unit 90 applies a detection pulse to the switching element Q3 via the drive circuit 80 in step S506. In step S507, the control unit 90 detects the detected current (Isne (v)) of the current sensor 41. In step S508, control unit 90 determines whether or not Isne (v) is equal to zero. If Isne (v) is equal to zero, the process proceeds to step S510.

  On the other hand, if Isne (v) is not equal to zero, the control unit 90 determines that the switching element Q4 is short-circuited (step S509), and proceeds to step S505.

  Returning to step S508, if Isne (v) is equal to zero, in step S510, the control unit 90 applies a detection pulse to the switching element Q5 via the drive circuit 80. In step S511, the control unit 90 detects the detection current (Isne (w)) of the current sensor 61. In step S512, control unit 90 determines whether or not Isne (w) is equal to zero. If Isne (w) is equal to zero, the process proceeds to step S514.

  On the other hand, if Isne (w) is not equal to zero, the control unit 90 determines that the switching element Q6 has a short circuit failure (step S513), and proceeds to step S505.

  Returning to step S512, if Isne (w) is equal to zero, in step S514, the control unit 90 applies a detection pulse to the switching element Q2 via the drive circuit 80. In step S515, control unit 90 detects the detection current (Ispc (u)) of current sensor 12. In step S516, control unit 90 determines whether Ispc (u) is equal to zero. If Ispc (u) is equal to zero, the process proceeds to step S518.

  On the other hand, if Ispc (u) is not equal to zero, the control unit 90 determines that the diode D2 is short-circuited (step S517), and proceeds to step S505.

  Returning to step S516, if Ispc (u) is equal to zero, in step S518, control unit 90 applies a detection pulse to switching element Q4 via drive circuit 80. In step S519, control unit 90 detects the detected current (Ispc (v)) of current sensor 32. In step S520, control unit 90 determines whether Ispc (v) is equal to zero. If Ispc (v) is equal to zero, the process proceeds to step S522.

  On the other hand, if Ispc (v) is not equal to zero, the controller 90 determines that the diode D4 is short-circuited (step S517), and proceeds to step S505. Returning to step S520, if Ispc (v) is equal to zero, the controller 90 determines that the remaining diode D6 is short-circuited (step S522), and proceeds to step S505.

  As described above, in this example, the switching elements Q1, Q3, and Q5 are located on the switching element Q1, Q3, and Q5 side of the connection point between the low potential side terminals of the positive side switching elements Q1, Q3, and Q5 and the anode terminals of the positive side diodes D1, D3, and D5. Are connected to the current sensors 11, 31, 51, and the switching elements Q 2, Q 4 are connected to a connection point between the low potential side terminals of the negative side switching elements Q 2, Q 4, Q 6 and the anode terminals of the negative side diodes D 2, D 4, D 6. The current sensors 21, 41, 61 are connected to the Q6 side. As a result, the detection values of the current sensors 11, 21, 31, 41, 51, 61 differ depending on the path of the current flowing through the failure points of the switching elements Q1 to Q6 and the diodes D1 to D6. The location of the short circuit failure in the circuit of the inverter 100 can be specified.

  In this example, a voltage sensor 73 for detecting an intermediate potential between the power supply lines PN is connected between the upper arm circuits 10, 30, 50 and the lower arm circuits 20, 40, 60. Thereby, it can be determined from the detection voltage of the voltage sensor 73 which of the upper arm circuits 10, 30, 50 and the lower arm circuits 20, 40, 60 has a short circuit failure. Further, before applying the detection pulse to the switching elements Q1 to Q6, it is possible to determine which one of the upper arm circuits 10, 30, 50 and the lower arm circuits 20, 40, 60 has a short-circuit failure. In particular, it is possible to reduce the control step when specifying which element of the switching elements Q1 to Q6 and the diodes D1 to D6 has a short-circuit fault, and as a result, shorten the time for specifying the fault location. It can be made. Further, if it is possible to specify which one of the upper arm circuits 10, 30, 50 and the lower arm circuits 20, 40, 60 has a short-circuit fault, the current flows through the failure path of the switching elements Q1 to Q6. Since the detection values of the sensors 11, 21, 31, 41, 51, and 61 are different, it is possible to specify at least which of the switching elements Q1 to Q6 has a short-circuit fault depending on the detection value pattern.

  Further, in this example, the current sensors 12, 32 are provided between the power line P and the collector terminal which is the high potential side terminal of the positive side switching elements Q1, Q3, Q5 and the cathode terminal of the positive side diodes D1, D3, D5. , 52 are connected. As a result, the detection values of the current sensors 11, 12, 21, 31, 32, 41, 51, 52, 61 differ depending on the path of the current flowing through the failure points of the switching elements Q1 to Q6 and the diodes D1 to D6. Depending on the value pattern, it is possible to specify which element of the switching elements Q1 to Q6 and the diodes D1 to D6 has a short-circuit fault.

  Further, in this example, when the control unit 90 determines from the detection voltage of the voltage sensor 73 that the upper arm circuits 10, 30, 50 are out of order, it applies a detection pulse to the switching elements Q2, Q4, Q6, Based on the detected currents of the current sensors 11, 31, 51, the failure location of the upper arm circuits 10, 30, 50 is specified. Thereby, it is possible to specify which element of the switching elements Q1, Q3, Q5 and the diodes D1, D3, D5 has a short-circuit fault.

  Moreover, in this example, the control part 90 is based on the detection current of the current sensors 11, 21, 31, 41, 51, 61 and the detection voltage of the voltage sensor 73, and the switching elements Q1 to Q6 that have failed from the inverter 100. Identify. Thereby, it is possible to specify which element among the switching elements Q1 to Q6 has a short circuit fault.

  Further, in this example, the control unit 90 has failed from the inverter 100 based on the detection current of the current sensors 11, 12, 21, 31, 32, 41, 51, 52, 61 and the detection voltage of the voltage sensor 73. The switching elements Q1 to Q6 and the diodes D1 to D6 are specified. Thereby, it is possible to specify which element of the switching elements Q1 to Q6 and the diodes D1 to D6 has the short circuit fault.

  Moreover, in this example, the control part 90 applies a detection pulse to the switching elements Q1-Q6 before controlling the motor 102, and pinpoints a failure location. Thus, by performing failure detection before the motor control of the motor 102 and the control for performing power conversion for the motor control, it is possible to safely inspect a short-circuit failure and then perform a fail operation. Can be transferred to.

  In this example, control part 90 applies a detection pulse to the gate terminal which is a control terminal of switching elements Q1-Q6 for a time shorter than the time when switching elements Q1-Q6 generate heat. Thereby, protection of switching elements Q1-Q6 can be aimed at.

  The voltage sensor 73 may be connected between the upper arm circuit 30 and the lower arm circuit 40 or between the upper arm circuit 50 and the lower arm circuit 60. Further, the reference potential of the voltage sensor 73 is not necessarily set to the potential on the negative electrode side, and a low-power ground may be used as the reference potential. In this example, the threshold voltage is Vpn, but a voltage lower than Vpn may be used as the threshold. In this example, the threshold voltage is set to 0 (V), but a voltage higher than 0 (V) may be used as the threshold.

  In this example, the inverter 100 is a three-phase conversion circuit. However, the inverter 100 is not necessarily required to have three phases, and may be multiphase. This example can also be applied to a series circuit including only the upper arm circuit 10 and the lower arm circuit 20. That is, for example, based on the detection voltage of the voltage sensor 73, it is determined whether the upper arm circuit 10 or the lower arm circuit 20 has a short circuit fault. For example, when it is specified that a short circuit failure has occurred in the upper arm circuit 10, the control unit 90 detects the current of the current sensor 11 by applying a detection pulse to the switching element Q2. If Ispe (u) is not zero, the switching element Q1 that should be off is conducting, so it is determined that a short-circuit fault has occurred in the switching element Q1. On the other hand, if Ispe (u) is zero, it is determined that a short-circuit fault has occurred in the diode D1, which is the remaining element among the circuit elements of the upper arm circuit 10 that have identified the short-circuit fault. The method for identifying the short-circuit fault of the lower arm circuit 20 is basically the same as the method of the upper arm circuit 10. A detection pulse is applied to the switching element Q 1, and the short-circuit location is determined based on the detection current of the current sensor 21. What is necessary is just to specify.

  Further, in this example, it is possible to specify at least which switching element among the switching elements Q1 to Q6 has a failure without connecting the current sensors 12, 32, and 52. That is, for example, based on the detection voltage of the voltage sensor 73, it is determined whether the upper arm circuit 10, 30, 50 or the lower arm circuit 20, 40, 60 has a short circuit fault. For example, when it is specified that a short circuit failure has occurred in the upper arm circuits 10, 30, 50, the control unit 90 applies a detection pulse to the switching element Q <b> 2 to detect the current of the current sensor 11. . If Ispe (u) is not zero, it is determined that a short circuit failure has occurred in switching element Q1. On the other hand, when Ispe (u) is zero, it is detected that the switching element Q1 is normal. Therefore, the control unit 9 determines the switching elements Q3 and Q5 for the other phases, V-phase and W-phase. Similar detection control of the short-circuited portion may be performed. The method for identifying the short-circuit fault in the lower arm circuits 20, 40, 60 is basically the same as the method for the upper arm circuits 10, 30, 50, and a detection pulse is applied to the switching elements Q1, Q3, Q5 to Based on the detected currents of the sensors 21, 41, 61, the short-circuit point may be specified.

  In this example, as shown in FIG. 7, instead of the voltage sensor 73, a current sensor 74, a connection point between the series circuit of the upper arm circuit 10 and the lower arm circuit 20 and the U-phase input unit of the motor 102, The current sensor 74 may be connected between the collector end of the switching element Q2 and the connection point of the casode terminal of the diode D2, and the current sensor 74 is a sensor that detects a current flowing from the U-phase input portion of the motor 102 to the lower arm circuit 20. FIG. 7 is a block diagram of a motor control system including a power converter according to a modification of the present invention.

  For example, when a short circuit failure occurs in the switching element Q1 or the diode D1, the control unit 90 applies a detection pulse to the switching Q2, so that a minute current flows through the upper arm circuit 10 and the switching element Q2 in the short circuit failure. Therefore, the current sensor 74 and the current sensor 21 detect the current. In addition, when the short-circuit failure occurs in the switching element Q3 or the diode D3, or the switching element Q5 or the diode D5, the control unit 90 applies a detection pulse to the switching Q2, so that a minute current is reduced due to the short-circuit failure. Since the current passes through the arm circuit 30 or the upper arm circuit 50 and flows through the switching element Q2 via the motor 102, the current sensor 74 and the current sensor 21 detect the current.

  When detecting whether or not a short circuit failure has occurred in the lower arm circuits 20, 40, 60, a detection pulse is applied to the switching element Q1, and a determination is made based on the detected currents of the current sensor 11 and the current sensor 12. Good. That is, for example, when a short circuit fault has occurred in the lower arm circuit 20, the control unit 90 applies a detection pulse to the switching Q1, and thus flows through the switching element Q1 and the lower arm circuit 20 of the short circuit fault. 11 and the current sensor 12 detect the current. In addition, when a short circuit failure occurs in the switching element Q2 or the diode D2, or the switching element Q4 or the diode D6, the control unit 90 applies a detection pulse to the switching Q1, so that a minute current causes the switching element Q1 to As described above, since the current flows through the lower arm circuit 40 or the upper arm circuit 60 via the motor, the current sensor 11 and the current sensor 12 detect the current.

  As a result, in this example, a short-circuit failure occurs in either the upper arm circuit 10, 30, 50 or the lower arm circuit 20, 40, 60 based on the detected current of the current sensor 74 and the detected current of the current sensors 11, 12. It can be identified whether it has occurred. Then, after specifying which of the upper arm circuits 10, 30, 50 and the lower arm circuits 20, 40, 60 has failed, the detection control process shown in FIG. 5 and the detection control process shown in FIG. 6 are performed. Thus, it is possible to specify which element of the switching elements Q1 to Q6 and the diodes D1 to D6 has a short-circuit fault. In the circuit shown in FIG. 7, when the failure of the lower arm circuits 20, 40, 60 is specified, the failure may be specified based on the current detected by the current sensors 31, 32 or the current sensors 51, 52.

  The current sensors 11, 31, 51 of this example correspond to the “first current detection means” of the present invention, and the current sensors 12, 32, 52 correspond to the “second current detection means”, the current sensors 21, 41 and 61 are “third current detection means”, the voltage sensor 73 is “voltage detection means”, the current sensor 74 is “fourth current detection means”, and the control unit 90 is “failure detection means” and “ The circuit of the inverter 100 corresponds to the “conversion circuit” as the “fault identification means”.

DESCRIPTION OF SYMBOLS 100 ... Inverter 10, 30, 50 ... Upper arm circuit 20, 40, 60 ... Lower arm circuit Q1-Q6 ... Switching element D1-D6 ... Diode 11, 12, 21, 31, 32, 41, 51, 52, 61, 74 ... Current sensor 71 ... Smoothing capacitor 72 ... Discharge resistor 73 ... Voltage sensor 80 ... Drive circuit 90 ... Control unit 101 ... Battery 102 ... Motor P, N ... Power line

Claims (12)

A switching element connected between power supply lines connected to the positive and negative ends of the power supply;
A diode connected in parallel with the switching element in a direction opposite to the direction of the current flowing when the switching element is forward conducting;
Current detection means for detecting a current connected to the switching element side from a connection point between the low potential side terminal of the switching element and the anode terminal of the diode;
And a failure detection means for detecting a failure of the switching element based on the detected current detected by the current detection means. The switching element is
A plurality of switching elements connected in series between the power lines;
The diodes are a plurality of diodes connected corresponding to the plurality of switching elements, respectively.
The current detection means includes
Of the plurality of switching elements, connected to the switching element side on the positive electrode side than the connection point between the low potential side terminal of the switching element on the positive electrode side and the anode terminal of the diode on the positive electrode side among the plurality of diodes, First current detection means for detecting
Of the plurality of switching elements, a low potential side terminal of the negative side switching element and a connection point between the anode terminal of the negative side diode of the plurality of diodes are connected to the negative side switching element side, and the current Second current detecting means for detecting
The failure detection means includes
The failure of the switching element is detected based on a detection current detected by the first current detection means and a detection current detected by the second current detection means. Power conversion device. A voltage connected between the upper arm circuit including the positive-side switching element and the positive-side diode and the lower arm circuit including the negative-side switching element and the negative-side diode and detects an intermediate potential between the both ends. A detection means;
The failure detection means includes the switching element and the diode based on a detection current detected by the first current detection means, a detection current detected by the second current detection means, and a detection voltage detected by the voltage detection means. The power conversion device according to claim 2, wherein a failure of the power is detected. A third current detection unit configured to detect a current connected between the power supply line on the positive electrode side and the high potential side terminal of the switching element on the positive electrode side and the cathode terminal of the diode on the positive electrode side;
The failure detection means includes a detection current detected by the first current detection means, a detection current detected by the second current detection means, a detection current detected by the third current detection means, and a voltage detection means. The power conversion device according to claim 3, wherein a failure of the switching element and the diode is detected based on a detection voltage detected by the step. A fourth current detecting means connected between the anode terminal of the positive-side diode and the high-potential-side terminal of the negative-side switching element and the cathode terminal of the negative-side diode;
The failure detection means includes a detection current detected by the first current detection means, a detection current detected by the second current detection means, a detection current detected by the fourth current detection means, and a voltage detection means. The power conversion device according to claim 3, wherein a failure of the switching element and the diode is detected based on a detection voltage detected by the step. A third current detection means for detecting a current connected between the power line on the positive electrode side and a high potential side terminal of the switching element on the positive electrode side and a cathode terminal of the diode on the positive electrode side;
A fourth current detection means for detecting a current, connected between the anode terminal of the positive side diode and the high potential side terminal of the negative side switching element and the cathode terminal of the negative side diode;
The failure detection means includes a detection current detected by the first current detection means, a detection current detected by the second current detection means, a detection current detected by the third current detection means, and the fourth current detection means. The power conversion device according to claim 2, wherein a failure of the switching element and the diode is detected based on a detected current detected by the current detecting means. The failure detection means further comprises failure identification means for identifying a failure location of a circuit included in the power conversion device,
The failure identification means is
When it is determined from the detection voltage of the voltage detection means that the upper arm circuit has failed, a signal for switching on and off the negative side switching element is output to the negative side switching element, and the first current detection means 6. The power conversion device according to claim 3, wherein a failure portion of the upper arm circuit is specified based on a detection current detected by the power conversion device. A plurality of the plurality of switching elements are connected in parallel between the power lines, and the plurality of diodes, the first current detection means, and the second current detection means are connected to the plurality of switching elements. And a multi-phase conversion circuit connected in correspondence with
The failure detection means further comprises failure identification means for identifying a failure location of the conversion circuit,
The failure identification means is
Based on the detection current of the first current detection means, the detection current of the second current detection means, and the detection voltage of the voltage detection means, a failure has occurred among the plurality of switching elements included in the conversion circuit. The power conversion device according to claim 3, wherein a switching element is specified. A plurality of the switching elements are connected in parallel between the power lines, and the plurality of diodes, the first current detection means, the second current detection means, and the third current detection means are provided. A multi-phase conversion circuit connected corresponding to each of the plurality of connected switching elements,
The failure detection means further comprises failure identification means for identifying a failure location of the conversion circuit,
The failure identification means is
Based on the detection current of the first current detection means, the detection current of the second current detection means, the detection current of the third current detection means, and the detection voltage of the voltage detection means, the conversion circuit 5. The power conversion device according to claim 4, wherein a faulty switching element and diode are identified from among the plurality of switching elements and the plurality of diodes included. A plurality of the switching elements are connected in parallel between the power lines, and the plurality of diodes, the first current detection means, the second current detection means, and the third current detection means are provided. A multi-phase conversion circuit connected corresponding to each of the plurality of connected switching elements,
The failure detection means further comprises failure identification means for identifying a failure location of the conversion circuit,
The failure identification means is
Based on the detection current of the first current detection means, the detection current of the second current detection means, the detection current of the third current detection means, and the detection current of the fourth current detection means, 7. The power conversion device according to claim 6, wherein a failed switching element and a diode are identified from the plurality of switching elements and the plurality of diodes included in the conversion circuit. With a motor connected to a connection point between the plurality of switching elements,
The failure detection means further comprises failure identification means for identifying a failure location of a circuit included in the power conversion device,
The failure identification means is
7. The failure point is specified by applying a signal for switching on and off of the switching element to the switching element before the motor is controlled. The power converter described. The failure detection means further comprises failure identification means for identifying a failure location of a circuit included in the power converter,
The failure identification means is
7. A signal for switching on and off of the switching element in order to specify the fault location is applied to a control terminal of the switching element for a time shorter than a time during which the switching element generates heat. The power converter device as described in any one of.

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