WO2022075202A1

WO2022075202A1 - Power conversion device and drive device

Info

Publication number: WO2022075202A1
Application number: PCT/JP2021/036345
Authority: WO
Inventors: 遼一稲田; 信康金川; 洋中野; 哲重田
Original assignee: 日立Astemo株式会社
Priority date: 2020-10-09
Filing date: 2021-09-30
Publication date: 2022-04-14
Also published as: JP2022062768A

Abstract

This power conversion device comprises fuses that fuse at a prescribed rated current or higher on respective three-phase output lines, the power conversion device comprising: a short-circuit failure sensing unit that senses short-circuit failures of switching elements that form a three-phase power conversion circuit; and a fuse fusing current control unit that, so that output current in a phase for which the short-circuit failure sensing unit sensed a short-circuit failure is at or higher than the rated current of the fuse, and output currents of the remaining two phases other than the phase for which the short-circuit failure was sensed are respectively below the rated currents of the fuses, controls the switching elements of the remaining two phases.

Description

Power converter and drive

The present invention relates to a power conversion device and a drive device.

If the switching element that constitutes the inverter fails due to a short circuit, the current of the failed phase cannot be controlled, and the motor output torque may become excessive or the winding of the motor may burn out. Therefore, a technique is known in which a fuse or the like is used to cut off the current of the phase that has failed in the event of a short-circuit failure.

Patent Document 1 discloses an electric motor drive device including a fuse for overcurrent protection and controlling a predetermined switching element to be turned on so as to blow the fuse when a part of the switching element of the inverter fails due to a short circuit. Have been described.

Japanese Patent Application Laid-Open No. 2011-223788

The motor drive device described in Patent Document 1 turns on a switching element in a normal phase for the purpose of surely blowing a fuse in a phase in which a short-circuit failure of the switching element occurs. In this case, since a larger current is passed through the faulty phase, a larger current is also passed through the normal phase, and not only the fuse in the faulty phase but also the fuse in the normal phase may be erroneously blown.

The power conversion device as one means for solving the above-mentioned problems is provided with a fuse that blows at a predetermined rated current or more on each of the three-phase output lines, and causes a short-circuit failure of the switching element constituting the three-phase power conversion circuit. The output currents of the short-circuit failure detection unit to be detected and the phase in which the short-circuit failure detection unit detects the short-circuit failure are equal to or higher than the rated current of the fuse, and the output currents of the remaining two phases different from the phase in which the short-circuit failure is detected are different. A fuse blown current control unit for controlling the remaining two-phase switching elements is provided so that each of the currents is less than the rated current of the fuse.

When a short-circuit failure of the switching element occurs, it is possible to prevent the fuse of the normal phase from being blown by mistake while blowing the fuse of the failed phase.

(Example 1) Configuration example of power conversion device 100 and drive device 200 (Example 1) Configuration example of power conversion circuit 30 and motor 190 (Embodiment 1) A table showing the internal state 19a determination of the state determination unit 19. (Example 1) Setting example of target current value 14a for each phase when the fuse is blown (Example 1) Example of current waveform during fuse blowout control (Example 2) Configuration example of power conversion device 100 and drive device 200 (Example 2) Configuration example of power conversion circuit 30 and motor 190 (Example 3) Configuration example of power conversion device 100 and drive device 200 (Example 3) Configuration example of power conversion circuit 30 and motor 190 (Example 3) Target current setting example of the target current calculation unit 14 when the fuse is blown (Example 3) Example of current waveform during fuse blowout control (Example 3) Current phase of the remaining two phases after the fuse is blown (Example 3) Example of current waveform and motor output torque waveform after fuse blown

FIG. 1 is a diagram showing a configuration example of the power conversion device 100 and the drive device 200 in this embodiment. In this embodiment, an example of a power conversion device and a drive device that blows only the fuse of the failed phase without blowing the fuse of the normal phase when a short-circuit failure of the power semiconductor occurs is shown.

The drive device 200 has a power conversion device 100 and a motor 190. The motor 190 is a three-phase motor having three windings inside, and corresponds to, for example, a synchronous motor using a permanent magnet or an induction motor not using a permanent magnet. Further, the motor 190 is equipped with an angle sensor (not shown) for measuring the electric angle of the motor, and this angle sensor outputs the measured electric angle as an angle sensor value θ to the power conversion device 100. do.

Around the drive device, there are an electronic control device (not shown), a DC power supply 210, and an abnormality notification device 220. The electronic control device notifies the drive device 200 of information such as a target torque. The DC power supply 210 is a power supply for driving the motor 190, and corresponds to, for example, a battery. The abnormality notification device 220 receives the failure notification signal from the drive device 200 and notifies the passenger of the occurrence of the failure. Examples of the failure notification method include a method of turning on a lamp, generating a warning sound, and notifying by voice.

The power conversion device 100 converts the DC power obtained from the DC power supply 210 into AC power to drive the motor 190. Further, the power conversion device 100 also has a function of converting the power of the motor 190 into DC power to charge the DC power supply 210. The power conversion device 100 has a control circuit 10, a driver circuit 20, a power conversion circuit 30, a voltage sensor 40, an alternating current sensor 50, and a fuse 60 inside. The power conversion circuit 30 receives a drive signal 21 from the driver circuit 20 to drive an internal power semiconductor and controls the current flowing through the motor 190. The internal configuration of the power conversion circuit 30 will be described first with reference to FIG. 2, and the internal configuration and other configurations of the control circuit 10 will be described later.

FIG. 2 is a diagram showing a configuration example of the power conversion circuit 30 and the motor 190 in this embodiment. The power conversion circuit 30 has a smoothing capacitor 31 and six power semiconductor elements 32 inside.

The smoothing capacitor 31 is a capacitor for smoothing the current generated by turning on / off the power semiconductor element 32 and suppressing the ripple of the DC current supplied from the DC power supply 210 to the power conversion circuit 30. For the smoothing capacitor 31, for example, an electrolytic capacitor or a film capacitor is used.

The power semiconductor element 32 switches on / off according to the drive signal 21 input from the driver circuit 20, and converts DC power and AC power. The power semiconductor element 32 corresponds to, for example, a power MOSFET (Metal Oxide Semiconductor Field Transistor), an IGBT (Insulated Gate Bipolar Transistor), or the like. Further, the power semiconductor element 32 of this embodiment has a sense terminal 33. From the sense terminal 33, a certain percentage of the current flowing between the collector and the emitter (between the drain and the source) of the power semiconductor element 32, for example, a current of 1/1000 or 1/1000 is output as a sense current. The sense current is output from the power conversion circuit 30 to the driver circuit 20. In the following examples, an example in which an IGBT is used as the power semiconductor element 32 will be described.

The six power semiconductor elements 32 are divided into upper and lower two for each phase, and the output is connected to the winding of each phase of the motor 190. Further, in this embodiment, the upper three power semiconductor elements 32 are collectively referred to as an upper arm, and the lower three power semiconductor elements 32 are collectively referred to as a lower arm.

Although the motor neutral point 191 is in a floating state in this embodiment, it may be connected to the ground (not shown). Methods for connecting the motor neutral point 191 to the ground include a direct grounding method, a resistance grounding method, a compensating reactor grounding method, an arc extinguishing reactor grounding method, and the like.

Returning to FIG. 1, the configuration of this embodiment will be described. The fuse 60 is installed on the output line of each phase between the power conversion circuit 30 and the motor 190, respectively. The fuse 60 blows when a current equal to or higher than the fuse rated current flows for a certain period of time or longer, and cuts off the current between the power conversion circuit 30 and the motor 190.

In this embodiment, the fuse 60 is installed in the power conversion device 100, but it may be installed in the motor 190 as in the case of the second embodiment described later, or the power conversion device 100 and the motor 190. It may be provided independently of. When the fuse 60 is installed in the power conversion device 100, there is an advantage that the replacement work of the fuse 60 becomes easy.

The voltage sensor 40 is a sensor that measures the output voltage of the DC power supply 210, and outputs the measured voltage value to the control circuit 10 as the voltage sensor value 40a.

The AC current sensor 50 is a sensor that measures the AC current flowing in each phase (U phase, V phase, W phase) of the motor 190, and the measured AC current of each phase is set as the AC current sensor value 50a in the control circuit 10. Output. In this embodiment, three AC current sensors 50 are provided, one for each phase, but AC current sensors may be provided only for two phases. In this case, since the relationship of U-phase current + V-phase current + W-phase current = 0 is established, the control circuit 10 calculates the AC current sensor value for the remaining one phase by calculation. In this embodiment, the current flowing from the power conversion circuit 30 to the motor 190 is treated as a positive current, and the current flowing from the motor 190 to the power conversion circuit 30 is treated as a negative current.

The driver circuit 20 receives the PWM (Pulse Width Modulation) signal 16a output by the PWM signal generation unit 16 described later, and outputs a drive signal 20a for switching on / off of the power semiconductor element 32. Further, the driver circuit 20 detects the occurrence of a short-circuit failure of the power semiconductor element 32 by using the sense current 33a output from the power semiconductor element 32, and outputs the short-circuit failure detection signal 20b to the control circuit 10.

Normally, the PWM signal 16a is generated so that the upper and lower power semiconductor elements 32 are not turned on at the same time, but if the power semiconductor element 32 fails in a short circuit, the upper and lower power semiconductor elements 32 can be turned on at the same time. When the upper and lower power semiconductor elements 32 are turned on at the same time, a large through current flows through the power semiconductor element 32. The driver circuit 20 monitors whether the sense current 33a of each power semiconductor element 32 is equal to or higher than a certain threshold value, and if the sense current 33a is equal to or higher than a certain value, the power semiconductor element 32 fails in a short circuit in the corresponding phase. It is determined that there is. Then, the driver circuit 20 outputs a short-circuit failure detection signal 20b separated for each phase.

In this embodiment, the short-circuit failure of the power semiconductor element 32 is determined by using the sense current 33a of the power semiconductor element 32, but the short-circuit failure of the power semiconductor element 32 may be detected by another method. For example, there is a method in which a shunt resistor for current measurement is arranged on the collector side or the emitter side of the power semiconductor element 32, and the current value flowing through the shunt resistor is measured to detect a short-circuit failure of the power semiconductor element 32. Further, since the collector-emitter voltage of the power semiconductor element 32 increases according to the flowing current, there is also a method of measuring the collector-emitter voltage to detect a short-circuit failure of the power semiconductor element 32.

The control circuit 10 communicates with an external electronic control device (not shown) and receives the target torque T * of the motor 190 from the electronic control device. When the power conversion device 100 is normal, the control circuit 10 outputs a PWM signal 16a so as to control the current of each phase output from the power conversion device 100 to a predetermined value based on this target torque T *. Then, the power conversion circuit 30 is driven via the driver circuit 20. Further, when the control circuit 10 determines that a failure has occurred inside the power conversion device 100, the control circuit 10 outputs an abnormality notification signal to the external abnormality notification device 220.

The control circuit 10 has a CPU, RAM, ROM, and a communication circuit inside (none of them are shown). This ROM may be an electrically rewritable EEPROM (Electrically Erasable Project ROM) or a flash ROM.

Further, the control circuit 10 includes a motor speed calculation unit 11, a torque control target current calculation unit 12, a torque control current control unit 13, a fuse blow target current calculation unit 14, a fuse blow current control unit 15, and a PWM signal generation. It has a unit 16, a short-circuit failure location determination unit 17, a fuse blowout determination unit 18, and a state determination unit 19.

The motor speed calculation unit 11 calculates the motor rotation speed from the change in the angle sensor value θ of the motor, and outputs the calculated motor speed value 11a to the torque control target current calculation unit 12.

The torque control target current calculation unit 12 outputs the target current value 12a to the torque control current control unit 13 using the target torque T *, the voltage sensor value 40a, and the motor speed value 11a output by the motor speed calculation unit 11. do. The target current value 12a is calculated as a current value to be passed through the motor 190 in order for the motor 190 to output the same torque as the target torque T *. The target current value 12a is represented, for example, in the form of a d-axis target current value and a q-axis target current value.

The torque control current control unit 13 uses the target current value 12a output by the torque control target current calculation unit 12, the motor angle sensor value θ, the AC current sensor value 50a of each phase, and the voltage sensor value 40a for each phase. The duty value 13a is calculated, and the duty value 13a is output to the PWM signal generation unit 16.

The fuse blown target current calculation unit 14 determines the target current of each phase during fuse blown control based on the short-circuit failure location information 17a of the power semiconductor element 32 output by the short-circuit failure location determination unit 17, and this target. The current value 14a is output to the current control unit 15 when the fuse is blown. Details of the method for determining the target current value 14a will be described later.

The fuse blown current control unit 15 has a target current value 14a output by the fuse blown target current calculation unit 14, a motor angle sensor value θ, an AC current sensor value 50a for each phase, a voltage sensor value 40a, and a power semiconductor element 32. Using the short-circuit failure location information 17a, the duty value 15a for each phase is calculated and output to the PWM signal generation unit 16.

The PWM signal generation unit 16 switches the signal to be output to the driver circuit 20 according to the internal state 19a output from the state determination unit 19. The PWM signal generation unit 16 has a timer inside, and when the internal state 19a is the "normal state", the timer value and the duty 13a of each phase output by the torque control current control unit 13 are set. The PWM signal 16a is output to the driver circuit 20 by the use. When the internal state 19a is "during a short-circuit failure of the power semiconductor element", the PWM signal generation unit 16 drives the PWM signal 16a using the timer value and the duty 15a of each phase output by the current control unit 15 when the fuse is blown. Output to circuit 20. When the internal state 19a is the "state after the fuse is blown", the PWM signal generation unit 16 outputs the PWM signal 16a so that the motor 190 is not driven to the driver circuit 20. The state in which the motor 190 is not driven includes, for example, a state in which all six power semiconductor elements 32 in the power conversion circuit 30 are turned off (referred to as a freewheel state in this embodiment).

The short-circuit failure location determination unit 17 determines the short-circuit failure location of the power semiconductor element 32 based on the PWM signal 16a and the short-circuit failure detection signal 20b output by the driver circuit 20. Since the short-circuit failure detection signal 20b output by the driver circuit 20 is separated for each phase, it is possible to specify in which phase the failure occurred, but it is not possible to specify which of the upper and lower arms is failed. Therefore, by comparing the timing at which the short-circuit failure detection signal 20b is output with the state of the PWM signal 16a, the short-circuit failure detection signal 20b of the PWM signals 16a of the upper and lower arms of the phase in which the failure has occurred is in the off state. It is determined that a short circuit failure has occurred in the arm. This is because the upper and lower power semiconductor elements 32 are not normally turned on at the same time, so that a short-circuit failure of the power semiconductor element 32 is detected is a short circuit in the power semiconductor element 32 that should be in the off state. This is because it is considered that a failure has occurred and the upper and lower power semiconductor elements 32 are turned on at the same time. The short-circuit failure location determination unit 17 uses the short-circuit failure location information 17a of the power semiconductor element 32 as a fuse blown target current calculation unit 14, a fuse blown current control unit 15, a fuse blowout determination unit 18, a state determination unit 19, and an external abnormality. Output to the notification device 220.

The fuse blown determination unit 18 determines whether the fuse 60 of the failed phase has blown based on the short-circuit failure location information 17a output from the short-circuit failure location determination unit 17 and the AC current sensor value 50a of each phase. The fuse blowout determination signal 18a is output to the state determination unit 19. When the short-circuit failure of the power semiconductor element 32 is detected, the control circuit 10 controls the current of each phase so as to blow the fuse 60 of the failed phase. Therefore, a current exceeding the rated current of the fuse 60 flows in the failed phase, but when the fuse 60 is blown, no current flows in the failed phase. The fuse blown determination unit 18 monitors the AC current sensor value 50a of the phase in which the short-circuit failure has occurred, and when the state in which the AC current sensor value 50a is below the threshold value continues for a certain period of time or longer, the fuse 60 of the failed phase is released. It is determined that the fuse has been blown.

The state determination unit 19 of the power conversion device 100 is based on the short-circuit failure location information 17a of the power semiconductor element 32 output by the short-circuit failure location determination unit 17 and the fuse blowout determination signal 18a output by the fuse blowout determination unit 18. It is determined whether the state is any of "normal state", "power semiconductor element short circuit failure state", and "fuse blown state". Then, the current state (19a) is output to the PWM signal generation unit 16.

FIG. 3 is a table showing the internal state determination of the state determination unit 19. The state determination unit 19 determines the next state from the current state and the occurrence item at regular time intervals, and updates the next state to the current state. The initial state is the "normal state". First, when the state determination unit 19 receives the short-circuit failure location information 17a of the power semiconductor element 32 from the short-circuit failure location determination unit 17 when the current state is the "normal state", the state determination unit 19 sets the next state to "power semiconductor element short circuit". Change to "failure state". Otherwise, the next state remains "normal". Further, when the current state is the "power semiconductor element short circuit failure state" and the fuse blown determination signal 18a is received from the fuse blown determination unit 18, the state determination unit 19 changes the next state to the "fuse blown state". .. In other cases, the next state remains the "power semiconductor device short circuit failure state". When the current state is the "state after the fuse is blown", the state determination unit 19 keeps the next state as the "state after the fuse is blown".

In the current control during torque control, the torque control target current calculation unit 12 shown in FIG. 1 first determines the d-axis target current value and the q-axis target current value according to the target torque T *. Next, the torque control current control unit 13 calculates the duty value 13a of each phase that achieves the d-axis target current value and the q-axis target current value determined by the torque control target current calculation unit 12. Then, the PWM signal generation unit 16 generates the PWM signal 16a of each phase according to the duty value 13a of each phase calculated by the torque control current control unit 13.

The torque control current control unit 13 converts the three-phase AC current sensor value 50a output from the AC current sensor 50 into the d-axis and q-axis current values using the motor angle sensor value θ. Next, the torque control current control unit 13 takes the difference between the d-axis current and the d-axis target current value, and the difference between the q-axis current and the q-axis target current value. Then, the torque control current control unit 13 performs feedback control on the d-axis current difference and the q-axis current difference, and determines the d-axis target voltage value and the q-axis target voltage value. The torque control current control unit 13 converts the d-axis target voltage value and the q-axis target voltage value into the form of the α-axis target voltage value and the β-axis target voltage value so as to be the values of the α-axis and the β-axis. Then, the torque control current control unit 13 converts the α-axis target voltage value and the β-axis target voltage value into the target voltage values of each of the U phase / V phase / W phase. Finally, the torque control current control unit 13 calculates the duty value 13a of each phase from the target voltage value and the voltage sensor value 40a of each phase.

The conversion from the α-axis target voltage value (Vα) and β-axis target voltage value (Vβ) to the U-phase target voltage value (Vu), V-phase target voltage value (Vv), and W-phase target voltage value (Vw) is When using the absolute conversion coefficient, the conversion is performed using [Equation 1]. [Equation 2] is used when converting from the target voltage value of each phase to the α-axis / β-axis target voltage value using the coefficient of absolute conversion.

To control the current when the fuse is blown, first, the target current calculation unit 14 when the fuse is blown determines the target current value 14a of each phase when the fuse is blown. Then, using [Equation 3], the U-phase target current value (Iu), the V-phase target current value (Iv), and the W-phase target current value (Iw) are set to the d-axis target current value (Id) and the q-axis target current. Convert to value (Iq). Note that θ in [Equation 3] is an angle sensor value.

Next, in the fuse blown current control unit 15, the duty value 15a of each phase that achieves the d-axis target current value and the q-axis target current value determined by the fuse blown target current calculation unit 14 is calculated. Then, the PWM signal generation unit 16 generates the PWM signal 16a for each phase according to the duty value 15a for each phase calculated by the current control unit 15 when the fuse is blown.

FIG. 4 is an example of setting the target current value 14a of each phase when the fuse is blown. In the fuse blowout control, when the power semiconductor element 32 of a certain phase is short-circuited, a current equal to or higher than the fuse rated current is passed through the failed phase, and a current less than the fuse rated current is passed through the remaining two phases. .. Therefore, the target current value 14a of the failed phase is set so that the absolute value of the target current value is equal to or larger than the fuse rated current. The target current value 14a of the remaining two phases is set so that the absolute value of the target current value is less than the fuse rated current. Further, the target current value 14a of each phase is set so as to satisfy the U phase target current value + V phase target current value + W phase target current value = 0.

When the power semiconductor element of the upper arm is short-circuited, the current of the faulty phase tends to flow from the power conversion circuit 30 toward the motor 190. Therefore, the target current calculation unit 14 at the time of fuse blowing is the target of the faulty phase. Set the current value to a positive value. When the power semiconductor of the lower arm is short-circuited, the current of the faulty phase tends to flow from the motor 190 toward the power conversion circuit 30, so that the target current calculation unit 14 at the time of fuse blown sets the target current value of the faulty phase. Set to a negative value.

Based on these, in the example of FIG. 4, when the U-phase upper arm short-circuit failure occurs, the U-phase target current value 14a is set to 1.8 times the fuse rated current, and the V-phase and W-phase target current values 14a are set to the fuse rated current. It is set to -0.9 times.

The reason why the target current value 14a of V phase and W phase is set to -0.9 times instead of -1.0 times the fuse rated current is that the current actually flowing in the control process exceeds the target current value. This is because the target current value is set a little lower in anticipation of this. It should be noted that this control error does not necessarily have to be 0.1 times the fuse rated current.

Similarly, when the U-phase lower arm short-circuit failure occurs, the U-phase target current value 14a is set to -1.8 times the fuse rated current, and the V-phase and W-phase target current values 14a are set to 0.9 times the fuse rated current. are doing.

When the V-phase upper arm short-circuit failure occurs, the V-phase target current value 14a is set to 1.8 times the fuse rated current, and the U-phase and W-phase target current values 14a are set to -0.9 times the fuse rated current. ing. When the V-phase lower arm short-circuit failure occurs, the V-phase target current value 14a is set to -1.8 times the fuse rated current, and the U-phase and W-phase target current values 14a are set to 0.9 times the fuse rated current. ..

When the W-phase upper arm short-circuit failure occurs, the W-phase target current value 14a is set to 1.8 times the fuse rated current, and the U-phase and V-phase target current values 14a are set to -0.9 times the fuse rated current. ing. When the W-phase lower arm short-circuit failure occurs, the W-phase target current value 14a is set to -1.8 times the fuse rated current, and the U-phase and V-phase target current values 14a are set to 0.9 times the fuse rated current. ..

In FIG. 4, the normal two-phase target current value 14a is set to the same value and the same direction, but it is not always necessary to set the same value and the target current value 14a in the same direction. However, if the normal two-phase target current value 14a is set in the same direction and the absolute value of the normal two-phase target current value 14a is made as large as possible within the range that does not exceed the fuse rated current, the target of the failed phase The absolute value of the current value 14a can be made larger. As a result, a large current can be passed through the faulty phase, and the fuse 60 in the faulty phase can be blown in a shorter time.

The duty value calculation by the fuse blown current control unit 15 is basically performed by the same procedure as the torque control current control unit 13. The difference is from the α-axis target voltage value (Vα) and β-axis target voltage value (Vβ) to the U-phase target voltage value (Vu), V-phase target voltage value (Vv), and W-phase target voltage value (Vw). Is the conversion part of. For example, in the case of a short-circuit failure of the U-phase upper arm power semiconductor element, when the voltage of the DC power supply is Vdc, the voltage output from the power semiconductor elements above and below the U-phase is fixed at 1/2 Vdc. Further, for example, when a short-circuit failure occurs in the U-phase lower arm power semiconductor element, the voltage output from the U-phase upper and lower power semiconductor elements is fixed at −1 / 2 · Vdc. Therefore, even if the normal U-phase, V-phase, and W-phase target voltages are converted, the power conversion circuit 30 cannot output the voltage as the target voltage. Therefore, it is necessary to calculate the target voltage of the remaining two phases in consideration of the deviation of the output voltage of the faulty phase.

When the U-phase power semiconductor element has a short-circuit failure, the target voltage values for the V-phase and W-phase are calculated by [Equation 4]. Here, when the voltage of the DC power supply 210 is Vdc, the value of the U-phase target voltage value (Vu) is 1/2 · Vdc, U-phase lower when the U-phase upper arm power semiconductor element is short-circuited. If the arm power semiconductor element has a short-circuit failure, it will be -1 / 2 · Vdc.

When the V-phase power semiconductor element has a short-circuit failure, the target voltage values for the U-phase and W-phase are calculated by [Equation 5]. Here, the value of the V-phase target voltage value (Vv) is 1/2 · Vdc when the V-phase upper arm power semiconductor element has a short-circuit failure, and when the V-phase lower arm power semiconductor element has a short-circuit failure. Is -1 / 2 · Vdc.

When the W-phase power semiconductor element fails due to a short circuit, the target voltage values for the U-phase and V-phase are calculated by [Equation 6]. Here, the value of the W phase target voltage value (Vw) is 1/2 · Vdc when the W phase upper arm power semiconductor element has a short circuit failure, and when the W phase lower arm power semiconductor element has a short circuit failure. Is -1 / 2 · Vdc.

FIG. 5 is a diagram showing an example of a current waveform at the time of fuse blowout control in this embodiment. In the example of FIG. 5, when the U-phase upper arm power semiconductor element is short-circuited, the U-phase target current value is 1.4 times the fuse rated current and the V-phase target current value is −0.9 times the fuse rated current. , The W phase target current value is set to -0.5 times the fuse rated current. In the example of FIG. 5, the current flowing through each phase is almost the same as the target current value, the current value of the failed U phase is equal to or higher than the fuse rated current, and the normal V phase and W phase currents are lower than the fuse rated current. It can be controlled so as to be.

In the example shown in FIG. 5, in order to explain the fuse blown control after the short-circuit failure of the power semiconductor element occurs, the current continues to flow even after the short-circuit failure occurs. However, in reality, the fuse of the U phase blows after a predetermined time elapses after the current of the fuse rated current or more starts to flow in the U phase, and the fuse shifts to the free wheel state. Further, although different target current values are set so that the current waveforms of the V-phase current and the W-phase current do not overlap in the drawings, naturally, the target current values may be set as in the example shown in FIG. It may be set to the value of.

As described above, in this embodiment, when a short-circuit failure of the power semiconductor element occurs, the current flowing through the failed phase is equal to or greater than the rated current of the fuse, and the current flowing through the remaining two phases is equal to or less than the rated current of the fuse. By controlling, only the fuse of the failed phase can be blown without blowing the normal two-phase fuse. Further, after the fuse in the faulty phase is blown, the power semiconductor element in the power conversion circuit is put into a freewheel state, so that the state in which the motor is not driven can be maintained.

In this embodiment, not only in the case of a short-circuit failure of the power semiconductor element 32, but also in the case of a ceiling fault or a ground fault of the motor winding, only the fuse 60 of the phase that has failed without blowing the fuse 60 of the normal phase is used. An example of the power conversion device 100 and the drive device 200 to be blown is shown.

FIG. 6 is a diagram showing a configuration example of the power conversion device 100 and the drive device 200 in this embodiment. The power conversion device 100 and the drive device 200 in this embodiment have different installation positions of fuses 60 from those in the first embodiment. Other elements are the same as in the first embodiment.

FIG. 7 is a diagram showing a configuration example of the power conversion circuit 30 and the motor 190 in this embodiment. In the first embodiment, the fuse 60 is installed between the power conversion circuit and the motor winding, but in the configuration of the second embodiment, the fuse 60 is installed on the motor neutral point side from the motor winding. In the case of the first embodiment, when the motor winding side of the fuse is connected to the positive side of the DC power supply 210 due to a failure (heavenly fault), or when the motor winding side is connected to the negative side of the DC power supply 210 due to a failure (ground fault). , The fuse 60 cannot cut off the current flowing through the motor winding of the faulty phase. When the fuse 60 is installed on the neutral point side of the motor with respect to the motor winding as in this embodiment, even if the motor winding has a ceiling fault or a ground fault, the fuse 60 is blown to create a motor with a failed phase. The current flowing through the winding can be cut off.

In this embodiment, when the power semiconductor element 32 is short-circuited, the fuse 60 of the normal phase is not blown, only the fuse of the failed phase is blown in a shorter time, and the rotary electric machine is continued to be driven even after the fuse is blown. An example of the power conversion device 100 and the drive device 200 that can be used is shown.

FIG. 8 is a diagram showing a configuration example of the power conversion device 100 and the drive device 200 in this embodiment. The power conversion device 100 and the drive device 200 in this embodiment have a driver circuit 20, a power conversion circuit 30, and a motor 190 having different configurations from those in the first embodiment. Further, the control circuit 10 in the power conversion circuit in the present embodiment has a current control unit 313 after the fuse is blown in addition to the control circuit of the first embodiment, and is different from the first embodiment in the target current when the fuse is blown. It has a calculation unit 14, a fuse blown current control unit 15, and a PWM signal generation unit 16. The description of the components common to the first embodiment will be omitted.

FIG. 9 is a diagram showing a configuration example of the power conversion circuit 30 and the motor 190 in this embodiment. In addition to the power conversion circuit of the first embodiment, the power conversion circuit 30 of the present embodiment has upper and lower power semiconductor elements for driving the motor neutral point voltage. The output of the power semiconductor element for driving the motor neutral point voltage is connected to the neutral point 191 of the motor 190. Further, the driver circuit 20 of the present embodiment has, in addition to the circuit of the first embodiment, a circuit for driving a power semiconductor element for driving the upper and lower motor neutral points connected to the motor neutral point 191. ..

In this embodiment, the fuse 60 is installed between the power conversion circuit and the motor winding, but even if the fuse 60 is installed on the motor neutral point side of the motor winding as in the second embodiment. good. Further, the fuse 60 may be installed between the output of the power semiconductor element for driving the motor neutral point voltage and the neutral point 191 of the motor 190.

The current control unit 313 after the fuse is blown in FIG. 8 uses the target current value 12a, the motor angle sensor value θ, the AC current sensor value 50a of each phase, and the voltage sensor value 40a output by the target current calculation unit 12 during torque control. , The duty value 313a of each phase and the neutral point of the motor is calculated and output to the PWM signal generation unit 16. Specific control of the current control unit 313 after the fuse is blown will be described later.

The PWM signal generation unit 16 of this embodiment switches the signal to be output to the driver circuit 20 according to the internal state 19a output from the state determination unit 19. When the internal state 19a is the "normal state", the PWM signal generation unit 16 generates the PWM signal 16a using the timer value and the duty value 13a of each phase output by the torque control current control unit 13. Output to the driver circuit 20. When the internal state 19a is a "power semiconductor element short-circuit failure state", the PWM signal generation unit 16 uses the timer value and the duty value 15a of each phase and the motor neutral point output by the current control unit 15 when the fuse is blown. Generates a PWM signal 16a and outputs it to the driver circuit 20. When the internal state 19a is the "state after the fuse is blown", the PWM signal generation unit 16 uses the timer value and the duty value 313a of each phase and the neutral point of the motor output by the current control unit 313 after the fuse is blown. Generates a PWM signal 16a and outputs it to the driver circuit 20.

Next, the current control at the time of fuse blown control in this embodiment will be described. At the time of fuse blown control in this embodiment, in addition to the current of each phase, the current flowing between the power semiconductor element for driving the motor neutral point voltage and the motor neutral point (hereinafter referred to as the motor neutral point current) is also controlled. do. Therefore, the fuse blown target current calculation unit 14 of the present embodiment sets a target current for the motor neutral point current (hereinafter referred to as a neutral point target current) in addition to the target current of each phase.

FIG. 10 is a diagram showing a target current setting example of the target current calculation unit 14 when the fuse is blown in this embodiment. Also in this embodiment, the absolute value of the target current of the short-circuited phase should be greater than or equal to the fuse rated current, and the absolute value of the target current of the remaining two phases should be less than the fuse rated current, as in Example 1. Set to. Further, when setting the target current value 14a for each phase and the neutral point, it is set so as to satisfy the U phase target current value + V phase target current value + W phase target current value + neutral point target current = 0.

When installing the fuse 60 between the output of the power semiconductor element for driving the neutral point voltage of the motor and the neutral point 191 of the motor 190, the absolute target current of the neutral point should not be blown by mistake. It is desirable that the value is less than the rated current of the fuse 60. If the fuse 60 is not installed between the output of the power semiconductor element for driving the motor neutral point voltage and the neutral point 191 of the motor 190, the absolute value of the neutral point target current is set to be less than the rated current of the fuse 60. However, the current may be set to be equal to or higher than the rated current of the fuse 60. Further, the neutral point target current is set so as to be in the direction opposite to the target current of the fault phase. By making the neutral point target current in the opposite direction to the target current of the faulty phase, the absolute value of the target current of the faulty phase can be increased, and a large current can be passed through the fuse of the faulty phase.

The fuse blown target current calculation unit 14 in the present embodiment sets the target currents of the set phases and the neutral points to the d-axis target current value (Id) and the q-axis target current value (Iq) using [Equation 7]. , Zero-phase target current value (Iz) is converted, and these values are output to the fuse blown current control unit 15. In this embodiment, since the neutral point target current is set, U-phase target current + V-phase target current + W-phase target current = 0 does not hold. Therefore, unlike the first embodiment, the zero-phase target current value is also calculated.

The fuse blown current control unit 15 of this embodiment calculates the duty of each phase in the same manner as the fuse blown current control unit of the first embodiment. Further, in this embodiment, since it is necessary to control the on / off of the power semiconductor element for driving the motor neutral point, the duty value for the motor neutral point is also calculated. The duty value for the neutral point of the motor is calculated as follows. First, the fuse blown current control unit 15 converts the AC current sensor value 50a for three phases output from the AC current sensor 50 into a zero-phase current value by using the motor angle sensor value θ. Next, the fuse blown current control unit 15 takes the difference between the zero-phase current and the zero-phase target current value. Then, the fuse blown current control unit 15 performs feedback control on the zero-phase current difference to determine the zero-phase target voltage value. The fuse blowing current control unit 15 uses the equation of [Equation 8] to obtain a neutral point target voltage value (Vn) from the zero-phase target voltage (Vz) and the target voltage value (Vu, Vv, Vw) of each phase. To calculate. At this time, the target voltage value of the phase in which the short-circuit failure of the power semiconductor element occurs is 1/2 · Vdc if the upper arm has a short-circuit failure when the voltage of the DC power supply 210 is Vdc, and the lower arm. If is short-circuited, calculate as -1 / 2 · Vdc. Finally, the fuse blown current control unit 15 calculates the duty value of the motor neutral point from the neutral point target voltage value and the voltage sensor value.

FIG. 11 is a diagram showing an example of a current waveform at the time of fuse blowout control in this embodiment. In the example of FIG. 11, when the U-phase upper arm power semiconductor element is short-circuited, the U-phase target current value is 2.1 times the fuse rated current, and the V-phase target current value is −0.9 times the fuse rated current. , The W phase target current value is set to -0.5 times the fuse rated current, and the neutral point target current value is set to -0.7 times the fuse rated current.

In the example of FIG. 11, the current of each phase and the neutral point current are almost the same as the target current values, the current value of the failed U phase is equal to or higher than the fuse rated current, and the normal V phase and W phase currents are. It can be controlled so that it is less than the fuse rated current. Further, by controlling the neutral point current so as to be opposite to the failed U-phase current, the absolute value of the U-phase current can be increased as compared with the current waveform of the first embodiment.

Next, the current control after the fuse is blown in this embodiment will be described. When the fuse 60 of the phase in which the short-circuit failure has occurred is blown, no current flows in that phase, and the state becomes the same as that of the open phase. At this time, torque ripple was suppressed by controlling the on / off of the power semiconductor element of the remaining two phases and the power semiconductor element for driving the neutral point voltage of the motor so that the current phase difference of the remaining two phases becomes 60 degrees. Torque control can be performed.

FIG. 12 is a diagram showing the current phases of the remaining two phases after the fuse is blown. Note that FIG. 12 is controlled in a state where the current phase of the V phase is delayed by 120 degrees from the current phase of the U phase and the current phase of the W phase is advanced by 120 degrees from the current phase of the U phase in the normal state. This is an example of the case. After the U-phase fuse is blown, the current is controlled so that the current phase of the W phase is advanced by 30 degrees from the normal phase and the current phase of the V phase is delayed by 30 degrees from the normal phase. After the V-phase fuse is blown, the current is controlled so that the U-phase current phase is advanced by 30 degrees and the W-phase current phase is delayed by 30 degrees. After the fuse of the W phase is blown, the current phase of the V phase is advanced by 30 degrees from the normal, and the current is controlled so as to delay the current phase of the W phase by 30 degrees from the normal. After the fuse is blown, the current control unit 313 calculates the duty of each phase and the neutral point of the motor so that the current phases of the remaining two phases are the values shown in FIG.

FIG. 13 is a diagram showing an example of a current waveform and a motor output torque waveform after the fuse is blown. (A) is the current and torque waveform in the normal state, and (b) is the current and torque waveform when the V-phase and W-phase currents are controlled with the same current phase as in the normal state after the U-phase fuse is blown. c) is a waveform of current and torque when the current phases of V phase and W phase are controlled as shown in FIG. 12 after the fuse of U phase is blown. In both (a), (b) and (c), the uppermost graph shows the current waveform of U phase / V phase / W phase. The middle graph shows the waveforms of the d-axis current and the q-axis current. The graph at the bottom shows the waveform of the output torque of the motor.

As shown in FIG. 13 (a), in the normal state, the current of each phase is controlled while maintaining a current phase difference of 120 degrees, and the d-axis current and the q-axis current at this time are both constant values. Therefore, the output torque also keeps a constant value.

As shown in FIG. 13 (b), when the current phases of the V phase and the W phase are set to the same values as usual after the fuse of the U phase is blown, the d-axis current and the q-axis current are oscillating according to the change in the electric angle. Increase or decrease to. Therefore, the output torque also vibrates and increases or decreases according to the change in the electric angle, and torque ripple occurs.

As shown in FIG. 13 (c), when the current phase difference between the V phase and the W phase is controlled to be 60 degrees after the fuse of the U phase is blown, the values of the d-axis current and the q-axis current are 1 in the normal state. Although it becomes / √3, it can maintain a constant value regardless of the change in the electric angle. Therefore, the output torque at this time is about 1 / √3 in the normal state, but a constant value can be maintained regardless of the change in the electric angle, and the occurrence of torque ripple as shown in FIG. 13B can be suppressed.

In the example of FIG. 13C, if the current amplitudes of the V phase and the W phase are √3 times the normal value, the values of the d-axis current and the q-axis current at that time can be the same as those in the normal state. The output torque can also be set to the same value as in the normal state.

As described above, in this embodiment, the absolute value of the faulty phase current can be increased by controlling the neutral point current so as to be in the opposite direction to the faulty phase current. Since the blown time of the fuse 60 becomes shorter as the current value flowing through the fuse 60 becomes larger, the fuse 60 in the failed phase can be blown faster by controlling the neutral point current as described above. Further, as in the present embodiment, by controlling the current phase difference of the remaining two phases to be 60 degrees after the fuse is blown, the torque control in which the torque ripple is suppressed can be continued even after the fuse is blown.

10: Control circuit 11: Motor speed calculation unit 11a: Motor speed value 12: Torque control target current calculation unit 12a: Target current value 13: Torque control current control unit 13a: Duty value 14: Fuse blow target current calculation unit 14a: Target current value 15: Current control unit at the time of fuse blown 15a: Duty value 16: PWM signal generation unit 16a: PWM signal 17: Short circuit failure location determination unit 17a: Short circuit failure location information 18: Fuse blowout determination unit 18a: Fuse blown Judgment signal 19: State determination unit 19a: Internal state 20: Driver circuit 20a: Drive signal 20b: Short circuit failure detection signal 30: Power conversion circuit 31: Smoothing capacitor 32: Power semiconductor element 33: Sense terminal 33a: Sense current 40: Voltage Sensor 40a: Voltage sensor value 50: AC current sensor 50a: AC current sensor value 60: Fuse 100: Power conversion device 190: Motor 191: Motor neutral point 200: Drive device 210: DC power supply 220: Abnormality notification device 313: Fuse Post-fusing current control unit

Claims

It is a power conversion device equipped with a fuse that blows at a predetermined rated current or more on each of the three-phase output lines.
A short-circuit failure detector that detects short-circuit failures of switching elements that make up a three-phase power conversion circuit, and a short-circuit failure detector.
The output current of the phase in which the short-circuit failure detection unit detects the short-circuit failure is equal to or higher than the rated current of the fuse, and the output currents of the remaining two phases different from the phase in which the short-circuit failure is detected are less than the rated current of the fuse. A power conversion device including a fuse blown current control unit that controls the remaining two-phase switching elements.
The power conversion device according to claim 1.
It has a neutral drive switching circuit whose output is connected to the neutral point of the motor.
The fuse blown current control unit is a power conversion device that controls the neutral point drive switching circuit so as to output a current in the direction opposite to the output current of the phase in which the short circuit failure is detected.
The power conversion device according to claim 2.
A fuse blown determination unit that determines the blown fuse in any phase,
After the fuse is determined to be blown by the fuse blown determination unit, the current control after the fuse is blown to control the remaining two-phase switching element different from the phase in which the fuse is blown and the neutral point drive switching circuit. A power converter equipped with a unit.
The power conversion device according to claim 3.
The fuse-blown current control unit is a power conversion device that controls the current phase difference between the remaining two phases of the switching element, which is different from the phase in which the fuse is blown, to be 60 degrees.
A drive device including a power conversion device that outputs a three-phase alternating current, a rotary electric machine that is driven by the three-phase alternating current, and a fuse that blows at a predetermined rated current or higher.
The fuse is provided in each phase between the neutral point of the rotary electric machine and the power conversion device.
The power converter is
A short-circuit failure detector that detects short-circuit failures of switching elements that make up a three-phase power conversion circuit, and a short-circuit failure detector.
The output current of the phase in which the short-circuit failure detection unit detects the short-circuit failure is equal to or higher than the rated current of the fuse, and the output currents of the remaining two phases different from the phase in which the short-circuit failure is detected are less than the rated current of the fuse. A drive device including a fuse blown current control unit that controls the remaining two-phase switching elements.
The drive device according to claim 5.
The fuse is a drive device provided between the winding of the rotary electric machine and the neutral point.
The driving device according to claim 5 or 6.
A neutral point drive switching circuit whose output is connected to the neutral point is provided.
The fuse blown current control unit is a drive device that controls the neutral point drive switching circuit so as to output a current in the direction opposite to the output current of the phase in which the short circuit failure is detected.
The drive device according to claim 7.
A fuse blown determination unit that determines the blown fuse in any phase,
After the fuse is determined to be blown by the fuse blown determination unit, the current control after the fuse is blown to control the remaining two-phase switching element different from the phase in which the fuse is blown and the neutral point drive switching circuit. A drive unit equipped with a unit.
The drive device according to claim 8.
The current control unit after the fuse is blown is a drive device that controls the current phase difference between the remaining two phases of the switching element, which is different from the phase in which the fuse is blown, to be 60 degrees.