JP2012039718A - Motor controller and motor control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller and a motor control method that prevent a current from flowing into a failed switching element concentrically.SOLUTION: The motor controller includes a plurality of pairs of switching elements Q1-Q6 connected to both ends of a DC power source through a power supply line, a rectifier element connected parallel to each of the plurality of pairs of switching elements Q1-Q6, a polyphase motor connected to a connection point of the plurality of pairs of switching elements, short-circuit failure detecting means which detects a short-circuit failure of the switching element, phase voltage detecting means which detects a phase voltage of each phase of the polyphase motor, and control means which controls on/off of the switching elements Q1-Q6 for converting a DC power of the DC power source to an AC power. When the short-circuit failure detecting means detects a short-circuit failure of the switching elements Q1-Q6, the control means controls the switching elements Q1-Q6 of a second phase according to a first phase voltage of a first phase including the switching elements Q1-Q6 of short-circuit failure and a second phase voltage of the second phase which is different from the first phase.

Description

  The present invention relates to a motor control device and a motor control method.

  In the power conversion device that converts the DC voltage supplied from the power source between the first and second power supply lines and the multiphase motor, the DC voltage is connected in series via the connection point with each phase coil of each phase motor. In response to the detection of the short-circuited arm circuit from among the plurality of arm circuits having the first and second switching elements, the first and second switching elements of the short-circuited arm circuit are in a conductive state. There is known a power conversion device that is fixed to the above.

JP 2008-54420 A

  However, in the conventional power conversion device, the resistance value may be different between the failed switching element and the non-failed switching element among the first and second switching elements. There was a possibility that current would concentrate on the side.

  The problem to be solved by the present invention is to provide a motor control device and a motor control method for preventing current from concentrating to flow in a failed switching element.

  According to the present invention, the switching element of the second phase is controlled by controlling the switching element of the second phase according to the phase voltage of the first phase and the phase voltage of the second phase including the switching element detected by the short-circuit fault detecting means. Solve the problem.

  According to the present invention, since the current flowing through the switching element in which the short-circuit fault is detected is shunted to the second-phase switching element, the current flows in a concentrated manner in the switching element in which the short-circuit fault is detected. The effect that can be prevented.

1 is a block diagram of a motor control device according to an embodiment of the present invention. FIG. 2 is a circuit diagram of the inverter and motor of FIG. 1 when a switching element has a short circuit failure. FIG. 2 is a circuit diagram of the inverter and motor of FIG. 1 when a switching element has a short circuit failure. FIG. 2 is a circuit diagram of the inverter and motor of FIG. 1 when a switching element has a short circuit failure. FIG. 2 is a circuit diagram of the inverter and motor of FIG. 1 when a switching element has a short circuit failure. It is a flowchart which shows the control processing of the motor control apparatus of FIG. It is a flowchart which shows the control processing of the motor control apparatus of FIG. 2 is a circuit of the equivalent circuit of FIG. 1 when a switching element is short-circuited. 8 is a graph showing voltage characteristics with respect to time in the upper arm circuit and the lower arm circuit of FIG. 7. It is a graph which shows the electric current characteristic of the phase voltage with respect to time in the circuit of FIG. It is a graph which shows the voltage characteristic of the capacitor | condenser with respect to time in the circuit of FIG.

  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 device according to an embodiment of the present invention. Although detailed illustration is omitted, the electric vehicle of this example is a vehicle that travels using a three-phase AC power permanent magnet motor 103 as a travel drive source, and the motor 103 is coupled to the axle of the electric vehicle. Hereinafter, an electric vehicle will be described as an example, but the present invention can also be applied to a hybrid vehicle (HEV).

  The motor control device of this example includes the above-described three-phase AC motor 103, the battery 101 that is a power source of the motor 103, the inverter 111 that converts the DC power of the battery 101 into AC power, the voltage sensor 105, the voltage Sensor 106.

  The battery 101 is a DC power source and is connected to the inverter 111. 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 111, 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 103 also functions as a generator, and AC power generated by the motor 103 is converted into DC by the inverter 111 and input to the battery 101, and the battery 101 is charged.

  The inverter 111 includes upper arm circuits 1041, 1043, and 1045, lower arm circuits 1042, 1044, and 1046, a smoothing capacitor 102, and a controller 108. The inverter 111 converts the DC power of the battery 101 into AC power. , Supplied to the motor 103. Upper arm circuits 1041, 1043, and 1045 are circuits in which switching elements Q1, Q3, and Q5 and diodes D1, D3, and D5 are connected in parallel, and lower arm circuits 1042, 1044, and 1046 are switching elements Q2, Q4. , Q6 and diodes D2, D4, and D6 are 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 4 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 example, FRD (Fast Recovery Diode) is used for each of the diodes D1 to D6.

  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 of the switching elements Q1 to Q6 is controlled by the controller 108 and switched at 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 controller 108. 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 current sensor 105 is a sensor that detects phase currents (Iu, Iv, Iw) flowing in the U phase, the V phase, and the W phase, and is connected to a conductive line that connects between the inverter 111 and the motor 103. The voltage sensor 106 is a sensor that detects phase voltages (Vu, Vv, Vw) of the U phase, the V phase, and the W phase, and is connected to a conductive line that connects between the inverter 111 and the motor 103. The phase voltage of each phase corresponds to the voltage at the connection point of switching elements Q1 and Q2, the connection point of switching elements Q3 and Q4, and the connection point of switching elements Q5 and Q6. Data detected by the current sensor 105 and the voltage sensor 106 is transmitted to the controller 108.

  The controller 108 is provided with a short-circuit fault detection unit 107. The short circuit failure detection unit 107 detects a short circuit failure of each of the switching elements Q1 to Q6 based on the phase currents (Iu, Iv, Iw) detected by the current sensor 105. For example, when a short-circuit failure occurs in the switching element Q1, even if all the switching elements Q1 to Q6 are controlled to be turned off, a closed circuit including the switching element Q1 that is a short-circuit portion is included in the circuit of the inverter 111. Will be formed. Then, for example, due to the electromotive force generated by the rotation of the motor 103, the U-phase current passes from the power supply line P line through the short-circuit portion (switching element Q1) and passes through the connection point between the switching elements Q1 and Q2. To the U-phase coil and to the V-phase coil and the W-phase coil. Then, the divided V-phase current and W-phase current flow through the diode D3 and the diode D5 and flow to the power supply line P. Similarly, with respect to the short-circuit faults of the other switching elements Q2 to Q6, when a short-circuit fault occurs, a closed circuit is formed in the circuit of the inverter 111 and an overcurrent flows. Therefore, the switching element Q1-Q6 in which the short circuit failure has occurred is identified by detecting the overcurrent that flows when the current sensor 105 is short-circuited and comparing the phase current of each phase detected by the short-circuit failure detection unit 107. Can do.

  The controller 108 sends a control signal to the gate terminals of the switching elements Q1 to Q6, and controls the switching elements Q1 to Q6 by, for example, PWM (Pulse Width Modulation) modulation. Further, the controller 108 turns on the switching elements Q1 to Q6 of phases other than the phase including the switching elements Q1 to Q6 including the short circuit fault when the short circuit fault detecting unit 107 causes the short circuit fault of the switching elements Q1 to Q6. As will be described later, the short-circuit current flowing through the switching elements Q1 to Q6 having the short-circuit failure is shunted.

  Next, the control content of the motor control device of this example will be described with reference to FIG. 2, taking as an example the case where the switching element Q4 has a short circuit failure. FIG. 2 is a schematic circuit for explaining the control processing of this example when the switching element Q4 has a short circuit failure, and is a circuit diagram in which the battery 101 and the like are omitted from FIG. Note that dotted arrows in FIG. 2 indicate the flow of current.

  When the short circuit failure detection unit 107 detects a short circuit failure of the switching element Q4 of the lower arm circuit 1044, the motor 103 rotates and a current flows in the inverter 111. In discharging the capacitor 102, the controller 108 performs the following control.

  First, the controller 108 detects the phase voltage (Vu, Vv, Vw) of each phase based on the voltage sensor 106, and compares the phase voltage (Vu, Vv, Vw) of each phase. When the phase voltage Vv is higher than the phase voltage Vw, the controller 108 turns on the switching element Q5 of the upper arm circuit 1045. When switching element Q5 is turned on, connection point between switching element Q5 to switching element Q5 and switching element Q6 to W phase coil and V phase coil to connection point between switching element Q3 and switching element Q4 to diode D3 to power supply line P A closed circuit is formed by the switching element Q5. When the closed circuit is formed by the control of the controller 108, the phase voltage Vv is higher than the phase voltage Vw as shown in FIG. 2, and therefore flows from the motor 103 toward the connection point between the switching element Q3 and the switching element Q4. The current flows toward the connection point of the diode D <b> 3 to the switching element 5 to the switching element 5 and the switching element 6. That is, the current that flows through the switching element Q4 that has failed is shunted in the forward direction of the diode D3, the current that flows through the switching element Q4 is limited, and the charge accumulated in the capacitor 102 is discharged. Thereby, the controller 108 includes the short-circuit fault switching element Q4 in the closed circuit for turning on the switching element Q5 and shunting the short-circuit current according to the comparison result of the phase voltages (Vu, Vv, Vw). Control to not.

  As described above, the controller 108 detects the phase voltage (Vu, Vv, Vw) by the voltage sensor 106 while the switching element Q5 is turned on and the current is flowing. Then, when the phase voltage Vv becomes equal to or lower than the phase voltage Vw, the controller 108 turns off the switching element Q5 that has been turned on.

  When the switching element Q4 is short-circuited and the phase voltage Vv is higher than the phase voltage Vu, the controller 108 limits the current flowing through the switching element Q4 by turning on the switching element Q1. be able to.

  Next, the control content of the motor control device of this example will be described with reference to FIG. 3, taking as an example the case where the switching element Q3 has a short circuit failure. FIG. 3 is a circuit diagram schematically illustrating the control process of this example when the switching element Q3 has a short circuit failure, and is a circuit diagram in which the battery 101 and the like are omitted from FIG. Note that the dotted arrows in FIG. 3 indicate the flow of current.

  When the short circuit failure detection unit 107 detects a short circuit failure of the switching element Q3 of the upper arm circuit 1043, the controller 108 performs the following control in discharging the capacitor 102.

  First, the controller 108 detects the phase voltage (Vu, Vv, Vw) of each phase based on the voltage sensor 106, and compares the phase voltage (Vu, Vv, Vw) of each phase. When the phase voltage Vv is lower than the phase voltage Vw, the controller 108 turns on the switching element Q6 of the lower arm circuit 1046. When switching element Q6 is turned on, switching element Q6, power line N, diode D4, connection point between switching element Q3 and switching element Q4, V phase coil, and W phase coil, connection point between switching element Q5 and switching element Q6 A closed circuit is formed by the switching element Q6. When the closed circuit is formed by the control of the controller 108, the phase voltage Vv is lower than the phase voltage Vw as shown in FIG. 3, and therefore flows from the motor 103 toward the connection point between the switching element Q5 and the switching element Q6. The current flows toward switching element Q6 to power supply line N. That is, a short circuit failure has occurred by flowing the current flowing from the motor 103 toward the connection point between the switching element Q5 and the switching element Q6 to the switching element Q6, not to the diode D5 to the power supply line P to the switching element Q3. The current flowing through the switching element Q3 is limited. Thereby, the controller 108 turns on the switching element Q6 according to the comparison result of the phase voltages (Vu, Vv, Vw), and the short-circuit fault switching element Q4 is not included in the closed circuit for shunting the current. Thus, the current flowing through the switching element Q3 is shunted.

  As described above, the controller 108 detects the phase voltage (Vu, Vv, Vw) by the voltage sensor 106 while the switching element Q6 is turned on and the current is flowing. Then, when the phase voltage Vv becomes equal to or higher than the phase voltage Vw, the controller 108 turns off the switching element Q6 that has been turned on.

  When the switching element Q3 is short-circuited and the phase voltage Vv is smaller than the phase voltage Vu, the controller 108 turns on the switching element Q2 to limit the current flowing through the switching element Q3 as described above. be able to.

  Next, taking the case where the switching element Q4 is short-circuited as an example, the control contents of the motor control device of this example will be described with reference to FIG. FIG. 4 is a circuit diagram schematically illustrating the control process of this example when the switching element Q4 has a short circuit failure, and is a circuit diagram in which the battery 101 and the like are omitted from FIG. Note that dotted arrows in FIG. 4 indicate the flow of current.

  When the short circuit failure detection unit 107 detects a short circuit failure of the switching element Q4 of the lower arm circuit 1044, the controller 108 performs the following control in discharging the capacitor 102.

  First, the controller 108 detects the phase voltage (Vu, Vv, Vw) of each phase based on the voltage sensor 106, and compares the phase voltage (Vu, Vv, Vw) of each phase. When the phase voltage Vv is lower than the phase voltage Vu, the controller 108 turns on the switching element Q2 of the lower arm circuit 1042. When the switching element Q2 is turned on, the switching element Q2, the power supply line N, the diode D6, the connection point between the switching element Q5 and the switching element Q6, the W phase coil, and the U phase coil, the connection point between the switching element Q1 and the switching element Q2. A closed circuit is formed by the switching element Q2. When the closed circuit is formed by the control of the controller 108, the phase voltage Vv is lower than the phase voltage Vu as shown in FIG. 4, and therefore flows from the motor 103 toward the connection point between the switching element Q1 and the switching element Q2. Current flows from switching element Q2 to power line N to diode D6 to connection point between switching element Q5 and switching element Q6 to the W-phase coil and U-phase coil. That is, the current flowing from the motor 103 to the inverter 111 does not flow toward the connection point between the motor 103 and the switching element Q3 and the switching element Q4, but at the connection point between the motor 103 and the switching element Q1 and the switching element Q2. It flows toward. For this reason, the current flowing through the switching element Q4 that is short-circuited is limited. Accordingly, the controller 108 turns on the switching element Q2 in accordance with the comparison result of the phase voltages (Vu, Vv, Vw), and the short-circuit fault switching element Q4 is not included in the closed circuit for shunting the current. Thus, the current flowing through the switching element Q4 is shunted.

  As described above, the controller 108 detects the phase voltage (Vu, Vv, Vw) by the voltage sensor 106 while the switching element Q2 is turned on and current is flowing. Then, when the phase voltage Vv becomes equal to or higher than the phase voltage Vu, the controller 108 turns off the switching element Q2 that has been turned on.

  When the switching element Q4 is short-circuited and the phase voltage Vv is lower than the phase voltage Vw, the controller 108 limits the current flowing through the switching element Q4 by turning on the switching element Q6. be able to.

  Next, the control content of the motor control device of this example will be described with reference to FIG. 5, taking as an example the case where the switching element Q3 has a short circuit failure. FIG. 5 is a circuit diagram schematically illustrating the control process of this example when the switching element Q3 has a short circuit failure, and is a circuit diagram in which the battery 101 and the like are omitted from FIG. Note that the dotted arrows in FIG. 5 indicate the flow of current.

  When the short circuit failure detection unit 107 detects a short circuit failure of the switching element Q3 of the upper arm circuit 1043, the controller 108 performs the following control in discharging the capacitor 102.

  First, the controller 108 detects the phase voltage (Vu, Vv, Vw) of each phase based on the voltage sensor 106, and compares the phase voltage (Vu, Vv, Vw) of each phase. When the phase voltage Vv is higher than the phase voltage Vu, the controller 108 turns on the switching element Q1 of the upper arm circuit 1041. When the switching element Q1 is turned on, the connection point between the switching element Q1 to the switching element Q1 and the switching element Q2 to the U phase coil and the W phase coil to the connection point between the switching element Q5 and the switching element Q6 to the diode D5 to the power line P A closed circuit is formed by the switching element Q1. When the closed circuit is formed by the control of the controller 108, the phase voltage Vv is higher than the phase voltage Vu as shown in FIG. 5, and therefore flows from the motor 103 toward the connection point between the switching element Q5 and the switching element Q6. The current flows from the diode D5 to the power supply line P to the switching element Q1. That is, the current flowing from the motor 103 to the power supply line P through the connection point between the switching element Q5 and the switching element Q6 and the diode D5 is caused to flow to the switching element Q1, thereby limiting the current flowing to the switching element Q3 having a short circuit failure. . As a result, the controller 108 turns on the switching element Q1 in accordance with the comparison result of the phase voltages (Vu, Vv, Vw), and the short circuit fault switching element Q3 is not included in the closed circuit for shunting the current. Thus, the current flowing through the switching element Q3 is shunted.

  As described above, the controller 108 detects the phase voltage (Vu, Vv, Vw) by the voltage sensor 106 while the switching element Q1 is turned on and the current is flowing. Then, when the phase voltage Vv becomes equal to or higher than the phase voltage Vw, the controller 108 turns off the switching element Q6 that has been turned on.

  When the switching element Q3 is short-circuited and the phase voltage Vv is higher than the phase voltage Vw, the controller 108 limits the current flowing through the switching element Q3 by turning on the switching element Q5. be able to.

  As described above, in this example, the switching elements Q1 to Q6 having phases that do not include the switching elements Q1 to Q6 having the short-circuit failure are determined depending on the magnitude relationship between the connection position in the inverter of the switching elements Q1 to Q6 having the short-circuit failure and the phase voltage at the connection point. Turn on Q6. That is, when the switching elements Q1 to Q6 of one phase in the multiphase cause a short circuit failure, the phase voltage of the one phase including the switching elements Q1 to Q6 of the short circuit failure and the phase voltage of the other phase In comparison, according to the magnitude relation of the phase voltage, the switching element of either the upper arm circuit or the lower arm circuit of the other phase is turned on, and the capacitor 102 is discharged. In other words, when one of the multi-phase switching elements Q1 to Q6 has a short circuit failure, the phase voltage of the one phase including the switching elements Q1 to Q6 of the short circuit failure and the phase of the other phase The switching elements Q1 to Q6 connected to the same power supply lines P and N as the short circuit failure switching elements Q1 to Q6 or the short circuit failure switching elements Q1 to Q6 are compared with each other in accordance with the magnitude relationship of the phase voltages. One of the switching elements Q1 to Q6 connected to the power supply lines P and N different from Q6 is turned on to discharge the capacitor 102. As a result, the controller 108 controls to discharge the capacitor 102 while limiting the current flowing through the switching elements Q1 to Q6 that are short-circuited.

  Next, the control procedure of this example will be described with reference to FIGS. 6a and 6b. 6a and 6b are flowcharts showing the control procedure of this example.

  First, in step S1, the short circuit detector 107 detects a short circuit failure of the switching elements Q1 to Q6. When a short circuit failure of the switching elements Q1 to Q6 is detected, the controller 108 detects the rotation of the motor 103 in step S2. The rotation of the motor 103 may be detected by, for example, the angular velocity sensor of the coil of the motor 103 or the current or voltage generated by the rotation of the motor 103 by the current sensor 105 or the voltage sensor 106.

  In step S <b> 3, the controller 108 detects phase voltages (Vu, Vv, Vw) based on the voltage sensor 106. In step S4, the controller 108 specifies whether or not the short-circuit faulty switching elements Q1 to Q6 detected in step S1 are the switching elements Q2, Q4, and Q6 of the lower arm circuits 1042, 1044, and 1046. The controller 108 grasps which switching element Q1 to Q6 has a short-circuit fault from the detection current of the current sensor 105 provided in each phase. If a short-circuit fault has occurred in the switching elements Q2, Q4, and Q6 of the lower arm circuit, the process proceeds to step S5. If a short-circuit fault has occurred in the switching elements Q1, Q3, and Q5 of the upper arm circuit, The process proceeds to step S41.

  In step S5, the controller 108 compares the phase voltage (Va) of the phase including the short-circuit faulty switching elements Q1 to Q6 with the phase voltage (Vb) of the phase not including the short-circuit faulty switching elements Q1 to Q6. . For example, when it occurs in the switching element Q2, the phase voltage of the U phase corresponds to Va, and the phase voltages of the V phase and the W phase correspond to Vb. When the phase voltage (Va) is higher than the phase voltage (Vb), the process proceeds to step S6, and when the phase voltage (Va) is equal to or lower than the phase voltage (Vb), the process proceeds to step S51. .

In step S6, the controller 108 turns on the switching elements Q1, Q3, Q5 of the upper arm circuits 1041, 1043, 1045 in the phase of the phase voltage (Vb) in step S5. For example, when a short circuit failure occurs in the switching Q1, and the phase voltage (Vu) is higher than the phase voltage (Vv), the switching element Q3 is turned on. In step S7, the accumulated charge in the capacitor 102 is discharged. In step S <b> 8, the controller 108 detects the phase voltage of each phase using the voltage sensor 106. In step S8, the controller 108 does not necessarily need to detect the phase voltages of all the phases. The phase voltage of the phase including at least the short-circuit faulty switching elements Q1 to Q6 and the switching element Q1 turned on in step S6. , Q3, and Q5 may be detected. In step S9, the controller 108 compares the phase voltages detected in step S8. If the phase voltage (Va) is higher than the phase voltage (Vb), in other words, if the magnitude relationship between the phase voltage (Va) and the phase voltage (Vb) in step S5 has not changed, the process returns to step S8. On the other hand, when the phase voltage (Va) is equal to or lower than the voltage of the phase voltage (Vb), in other words, when the magnitude relationship between the phase voltage (Va) and the phase voltage (Vb) in step S5 changes, the process proceeds to step S10. In step S10, the controller 108 turns off the switching elements Q1, Q3, and Q5 that were turned on in step S6, and ends the control process. Note that the control processing in steps S6 to S10 corresponds to the control content described above with reference to FIG.

If it is determined in step S5 that the phase voltage (Va) is equal to or lower than the phase voltage (Vb), in step S51, the controller 108 determines that the lower arm circuit 1042 of the phases of the phase voltage (Vb) in step S5. The switching elements Q2, Q4, Q6 of 1044, 1046 are turned on. For example, when a short circuit failure occurs in the switching Q1, and the phase voltage (Vu) is a voltage equal to or lower than the phase voltage (Vv), the switching element Q4 is turned on. In step S52, the accumulated charge in the capacitor 102 is discharged. In step S <b> 53, the controller 108 detects the phase voltage of each phase using the voltage sensor 106. In step S53, the controller 108 does not necessarily need to detect the phase voltages of all the phases, but the phase voltage of the phase including at least the short-circuit faulty switching elements Q1 to Q6 and the switching element Q2 turned on in step S51. , Q4, and Q6 may be detected.
In step S54, the controller 108 compares the phase voltages detected in step S8. If the phase voltage (Va) is equal to or lower than the phase voltage (Vb), in other words, if the magnitude relationship between the phase voltage (Va) and the phase voltage (Vb) in step S5 has not changed, the process returns to step S53. . On the other hand, when the phase voltage (Va) is higher than the phase voltage (Vb), in other words, when the magnitude relationship between the phase voltage (Va) and the phase voltage (Vb) in step S5 changes, the process proceeds to step S55. In step S55, the controller 108 turns off the switching elements Q2, Q4, and Q6 that were turned on in step S51, and ends the control process. Note that the control processing in steps S51 to S55 corresponds to the control content described above with reference to FIG.

  If a short circuit fault has occurred in switching elements Q1, Q3, and Q5 of upper arm circuits 1041, 1043, and 1045 by step S4, controller 108 includes switching elements Q1 to Q6 having a short circuit fault in step S41. The phase voltage (Va) of the phase is compared with the phase voltage (Vb) of the phase not including the short-circuit faulty switching elements Q1 to Q6. Then, according to the magnitude relationship between the phase voltage (Va) and the phase voltage (Vb), the controller 108 performs the control process of step S41 to step S47 or step S411 to S415. The control process of steps S41 to S47 is the same as the control process of steps S6 to S10, and the control process of steps S411 to S415 is the same as the control process of steps S51 to S55, and thus description thereof is omitted. Note that the control processing in steps S42 to S47 corresponds to the control content described above with reference to FIG. 5, and the control processing in steps S411 to S415 corresponds to the control content described with reference to FIG.

  As described above, in this example, when the short-circuit fault detection unit 107 detects a short-circuit fault of the switching elements Q1 to Q6, the controller 108 includes a phase including the short-circuit faulty switching elements Q1 to Q6 (“No. 1 phase) (corresponding to the “first phase voltage” of the present invention) and a phase different from the phase including the switching elements Q1 to Q6 that are short-circuited (the “second phase” of the present invention). ) In accordance with the phase voltage (corresponding to the “second phase voltage” of the present invention), the switching elements Q1 to Q6 of a phase different from the phase including the switching elements Q1 to Q6 that are short-circuited are controlled. To do. For example, in this example, when the short-circuit fault detection unit 107 detects a short-circuit fault of the switching element Q1, the controller 108 controls the phase voltage Vu (corresponding to the “first phase” of the present invention) of U phase (corresponding to the present invention). Corresponding to the "first phase voltage" of V) or the phase voltage Vv or Vw of the V phase or W phase (corresponding to the "second phase" of the present invention) (corresponding to the "second phase voltage" of the present invention). ), The V-phase or W-phase switching elements Q3 to Q6 are controlled.

  Here, unlike the present example, a case will be described in which switching elements Q1 to Q6 having the same phase as switching elements Q1 to Q6 having a short circuit failure are turned on to short-circuit between power supply line P and power supply line N. The resistance values of the switching elements Q1 to Q6 that are short-circuited vary depending on the material characteristics and the element structure. Therefore, since the resistance values of the switching elements Q1 to Q6 that are short-circuited are different from the resistance values of the switching elements Q1 to Q6 that are not short-circuited, the current is distributed among the short-circuited switching elements Q1 to Q6. There is a possibility that the (resistance ratio) is biased, the short-circuit current concentrates on the switching elements Q1 to Q6 with the short-circuit failure, and the amount of heat generated in the switching elements Q1 to Q6 with the short-circuit failure may increase.

  On the other hand, in this example, a switching element having a phase different from that of the switching elements Q1 to Q6 having a short circuit failure is turned on to limit a current flowing through the switching elements Q1 to Q6 having a short circuit failure, and The voltage applied to Q6 is lowered to suppress the power load applied to switching elements Q1 to Q6 having a short circuit failure. Therefore, it is possible to prevent the current from concentrating on the short-circuit faulty switching elements Q1 to Q6, and to suppress the amount of heat generated in the short-circuit faulty switching elements Q1 to Q6.

  Further, in this example, the controller 108 responds to the magnitude relationship between the phase voltage of the phase including the short-circuit faulty switching elements Q1 to Q6 and the phase voltage of a phase different from the phase including the short-circuit faulty switching elements Q1 to Q6. Thus, the switching elements Q1, Q3, Q5 of the upper arm circuits 1041, 1043, 1045 or the switching elements Q2, Q4 of the lower arm circuits 1042, 1044, 1046 in a phase different from the phase including the switching elements Q1-Q6 that are short-circuited. , Q6 is turned on. Thereby, it can prevent that an electric current concentrates on the switching elements Q1-Q6 of a short circuit failure, and can suppress the emitted-heat amount in the switching elements Q1-Q6 of a short circuit failure.

  In this example, the phase voltage (Vu, Vv, Vw) is detected by the voltage sensor 106, but the phase voltage (Vu, Vv, Vw) is detected by the voltage sensor that detects the intermediate potential (Vt) of the motor 103. You may measure. For example, for the U phase, if the internal resistance of the motor 103 is Ru, the phase voltage Vu is calculated by Equation 1.

[Formula 1]
Vu = Ru × Iu + Vu (Formula 1)
The phase current (Iu) is detected by the current sensor 105, and the internal resistance (Ru) is a resistance value set in advance at the design stage of the motor 103. Therefore, if a voltage sensor that detects the intermediate potential (Vt) is used instead of the voltage sensor 106, the phase voltage (Vu) can be detected. Similarly, voltage sensors that detect the intermediate potential (Vt) may be used for the other phases (V phase and W phase).

  In step S5 of this example, when the phase voltage (Va) and the phase voltage (Vb) are equal, the process proceeds to step S51. However, the process may proceed to step S6, and the process returns to step S3. Steps S3 to S5 may be repeated until a magnitude relationship is generated between the voltage (Va) and the phase voltage (Vb).

  In this example, when the magnitude relationship between the phase voltage (Va) and the phase voltage (Vb) is compared, the difference between the phase voltage (Va) and the phase voltage (Vb) may be compared. For example, when the difference between the phase voltage (Va) and the phase voltage (Vb) is higher than a predetermined voltage difference set in advance, it is determined that the phase voltage (Va) is higher than the phase voltage (Vb). That's fine.

  In this example, the short-circuit fault detection means 107 is a part of the controller 108, but may be another control unit different from the controller 108.

  The diodes D1 to D6 of this example correspond to the “rectifier element” of the present invention, the motor 103 is a “multiphase motor”, the current sensor 105 and the short-circuit fault detection means 107 are “short-circuit fault detection means”, and the voltage The sensor 106 corresponds to “phase voltage detection means”, and the controller 108 corresponds to “control means”.

  Examples that further embody the present invention will be described below.

"Evaluation methods"
Assuming the case where the switching element Q4 is short-circuited, the evaluation was performed using the equivalent circuit of FIG. FIG. 7 is an equivalent circuit for evaluating the present invention.

  As shown in FIG. 7, a resistor R (resistance value: 1 mΩ) that assumes a short circuit is connected to the switching element Q4 that has a short circuit failure. In order to detect the current flowing through the upper arm circuit and the lower arm circuit, ammeters 71 to 73, 75 and 76 are connected to the collector terminals of the switching elements Q1 to Q3, Q5 and Q6, and the ammeter 74 is connected to the resistor R. Connected. The power supply line N is grounded, and voltmeters 77 to 79 for detecting the phase voltage are connected between the conductive wires of each phase of the motor 103 and the power supply line N. The smoothing capacitor C1 has a capacity of 600 μF and can charge and discharge to an initial voltage of 0 to 400V. The rotation condition of the motor 103 was 500 rpm. The drive circuits 81 to 83, 85 and 86 are connected to the switching elements Q1 to Q3, Q5 and Q6, and switch the switching elements Q1 to Q3, Q5 and Q6 based on a control signal from the controller 108 (not shown). The detection currents of the ammeters 71 to 76 are AM1 to AM6, and the detection voltages of the voltmeters 77 to 79 are VM1 to VM3. The detection voltage VM1 corresponds to the phase voltage Vu, VM2 corresponds to Vv, and VM3 corresponds to Vw.

  The controller 108 detects a short circuit failure of the switching element Q4, and controls switching of the switching elements Q1, Q2, Q5, and Q5 according to the detection voltages VM1 to VM3 as in the above embodiment. Under the control of the controller 108, changes in the current flowing through the upper arm circuits 1041, 1043, and 1045 and the lower arm circuits 1042, 1044, and 1046, changes in the phase voltage of each phase, and changes in the voltage of the capacitor C1 were measured. The measurement results are shown in FIGS. 8 shows current characteristics with respect to time in the respective ammeters 71 to 76, FIG. 9 shows voltage characteristics with respect to time in the respective voltmeters 77 to 79, and FIG. 10 shows voltage characteristics with respect to time in the capacitor C1.

  Table 1 shows the results of measuring the peak current value of the current (corresponding to AM4) flowing through the resistor R assuming the short circuit failure, the peak voltage value of the phase voltage Vv (corresponding to VM2), and the load power. Note that the load power is the power that is converted in one cycle of the electrical angular velocity determined by the number of motor pole pairs and the number of rotations.

《考察》
図８に示すように、例えば１１５〜１３５（ｍｓｅｃ）の間、ＶＭ２はＶＭ３より高くなっている。本例の制御では、下アーム回路１０４２、１０４４、１０４６のスイッチング素子Ｑ４が故障し、相電圧Ｖｖが相電圧Ｖｗより高い場合に相当するため、スイッチング素子Ｑ５をオンにする制御が行われ、ダイオードＤ３の順方向に電流が流れる、ことになる（図２を参照）。図９に示すように、１１５〜１３５（ｍｓｅｃ）の間、ＡＭ３は、負方向に電流が流れることを示している。これにより、本例の制御を行うことで、モータ１０３から上アーム回路１０４３と下アーム回路１０４４との中間点に向けて流れる電流が、ダイオードＤ３の順方向を通るため、抵抗Ｒに流れる電流が分流されていることが分かる。

<Discussion>
As shown in FIG. 8, VM2 is higher than VM3 during, for example, 115 to 135 (msec). In the control of this example, this corresponds to the case where the switching element Q4 of the lower arm circuits 1042, 1044, and 1046 has failed and the phase voltage Vv is higher than the phase voltage Vw. A current flows in the forward direction of D3 (see FIG. 2). As shown in FIG. 9, AM3 indicates that a current flows in the negative direction during 115 to 135 (msec). Thus, by performing the control of this example, the current flowing from the motor 103 toward the intermediate point between the upper arm circuit 1043 and the lower arm circuit 1044 passes through the forward direction of the diode D3. You can see that it is diverted.

  As shown in Table 1, the current peak value and voltage peak value of the resistor R when the control of this example is performed are the current peak value and voltage peak value of the resistor R when the control of this example is not performed. It is lower than Thereby, it can be seen that the current flowing through the resistor R, which is the part of the short-circuit failure, is shunted, and the current flowing into the short-circuit fault part is limited.

  Further, the load power when the control of this example is performed is lower than the load power when the control of this example is not performed. Thereby, it turns out that the load electric power concerning a short circuit failure site | part is reduced to about half by performing control of this example.

  From the above results, it was confirmed that the current flowing through the switching elements Q1 to Q6 with the short circuit failure was limited by controlling the present example, and the load on the switching elements Q1 to Q6 with the short circuit failure was reduced.

DESCRIPTION OF SYMBOLS 101 ... Battery 102 ... Capacitor 103 ... Motor 1041, 1043, 1045 ... Upper arm circuit 1042, 1044, 1046 ... Lower arm circuit 105 ... Current sensor 106 ... Voltage sensor 107 ... Short-circuit fault detection part 108 ... Controller 111 ... Inverters Q1-Q6 ... switching elements D1 to D6 ... diodes 71 to 76 ... ammeters 77 to 79 ... voltmeters 81 to 83, 85, 86 ... drive circuit C1 ... capacitor R ... resistors P, Q ... power line

Claims (7)

A plurality of pairs of switching elements connected via power lines to both ends of the DC power supply;
A rectifying element connected in parallel to each of the plurality of pairs of switching elements;
A multiphase motor connected to a connection point of the plurality of pairs of switching elements;
A short-circuit fault detecting means for detecting a short-circuit fault of the switching element;
Phase voltage detection means for detecting a phase voltage of each phase of the multiphase motor;
Control means for controlling on and off of the switching element to convert DC power of the DC power source into AC power;
The control means includes
When a short circuit failure of the switching element is detected by the short circuit failure detection means,
In response to a first phase voltage of the first phase including the short-circuit faulty switching element and a second phase voltage of a second phase different from the first phase, the second phase A motor control device for controlling a switching element. The control means includes
According to the magnitude relationship between the first phase voltage and the second phase voltage, at least one of the switching element of the upper arm circuit of the second phase and the switching element of the second phase. The motor control device according to claim 1, wherein the switching element is turned on. The control means includes
When the short-circuit fault detecting means detects a short-circuit fault of the switching element of the lower arm circuit, and the first phase voltage is higher than the second phase voltage,
3. The motor control device according to claim 1, wherein the switching element of the upper arm circuit of the second phase is turned on. The control means includes
When the short-circuit fault detecting means detects a short-circuit fault of the switching element of the upper arm circuit, and the first phase voltage is lower than the second phase voltage,
The motor control device according to claim 1, wherein the switching element of the lower arm circuit of the second phase is turned on. The control means includes
When the short-circuit fault detection means detects a short-circuit fault of the switching element of the lower arm circuit, and the first phase voltage is lower than the second phase voltage,
The motor control device according to claim 1, wherein the switching element of the lower arm circuit of the second phase is turned on. The control means includes
When the short-circuit fault detection means detects a short-circuit fault of the switching element of the upper arm circuit, and the first phase voltage is higher than the second phase voltage,
3. The motor control device according to claim 1, wherein the switching element of the upper arm circuit of the second phase is turned on. Connected to both ends of the DC power supply via a power line, and controls on and off of a plurality of pairs of switching elements connected in parallel to the plurality of diodes, and converts the DC power of the DC power supply into AC power, Outputting the AC power to a multiphase motor connected to a connection point of the plurality of pairs of switching elements;
A short-circuit fault detection step of detecting a short-circuit fault of the switching element;
A phase voltage detection step of detecting a phase voltage of each phase of the multiphase motor;
When a short-circuit fault of the switching element is detected by the short-circuit fault detection step, the first phase voltage of the first phase including the short-circuit faulty switching element is different from the phase voltage of the first phase. And a step of controlling the switching element included in the second phase according to a second phase voltage of two phases.

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