JP2020115700A - Inverter device - Google Patents

Abstract

To enable a three-phase motor to be driven with a certain level of accuracy even when any one of each element of each phase of an inverter is short-circuited.SOLUTION: An inverter device comprises a neutral point clamp type three-level inverter which has a plurality of switching elements and a plurality of diodes as each element of each phase and drives a three-phase motor, and a controller for controlling the three-level inverter so that a three-level voltage is applied to each phase of the three-phase motor. When any one of each element of each phase is short-circuited, the controller controls the three-level inverter using an element which is not short-circuited among each element of each phase so that a two-level voltage is applied to each phase of the three-phase motor.SELECTED DRAWING: Figure 2

Description

The present invention relates to an inverter device, and more particularly to an inverter device including a neutral point clamp type three-level inverter.

Conventionally, as this type of inverter device, a device provided with a neutral point clamp type three-level inverter for driving a three-phase motor has been proposed (for example, refer to Patent Document 1). Here, the three-level inverter includes U-phase, V-phase, and W-phase first to fourth switches and first to fourth diodes, first to sixth clamp diodes, and first and second capacitors. Have. The U-phase, V-phase, and W-phase first to fourth switches are connected in series in this order to the positive electrode line and the negative electrode line on the DC side, respectively. U-phase, V-phase, and W-phase first to fourth diodes are connected in parallel to the U-phase, V-phase, and W-phase first to fourth switches, respectively. The U-phase, V-phase, and W-phase of the motor are connected to the connection points of the U-phase, V-phase, and W-phase second and third switches, respectively. The cathodes of the first, third, and fifth clamp diodes are connected to the connection points of the U-phase, V-phase, and W-phase first and second switches, respectively. The cathodes of the second, fourth and sixth clamp diodes are connected to the anodes of the first, third and fifth clamp diodes, respectively. The connection points of the U-phase, V-phase, and W-phase third and fourth switches are connected to the anodes of the second, fourth, and sixth clamp diodes, respectively. The first and second capacitors are connected in series in this order to the positive electrode line and the negative electrode line. At the connection point (neutral point) of the first and second capacitors, the connection point of the first and second clamp diodes, the connection point of the third and fourth clamp diodes, and the connection of the fifth and sixth clamp diodes. The points and are connected.

JP, 2016-220325, A

In such an inverter device, even when one of the U-phase, V-phase, W-phase first to fourth switches and the first to fourth diodes and any of the first to sixth clamp diodes is short-circuited, the three-phase It is required to drive a motor with a certain degree of accuracy.

The main purpose of the inverter device of the present invention is to enable the three-phase motor to be driven with a certain degree of accuracy even when any one of the elements of each phase of the inverter has a short circuit failure.

The inverter device of the present invention employs the following means in order to achieve the main object described above.

The inverter device of the present invention is
A neutral point clamp type three-level inverter that has a plurality of switching elements and a plurality of diodes as each element of each phase and drives a three-phase motor,
A controller for controlling the three-level inverter so that three-level voltage is applied to each phase of the three-phase motor;
An inverter device comprising:
When any one of the elements of each of the phases has a short circuit failure, the controller uses two elements of each of the phases of the three-phase motor by using two elements of each phase of the three-phase motor. Controlling the three-level inverter so that the voltage of
That is the summary.

In this inverter device of the present invention, when any one of the elements of each phase (a plurality of switching elements and a plurality of diodes) has a short-circuit failure, the elements not having a short-circuit failure among the elements of each phase are used. The 3-level inverter is controlled so that 2-level voltage is applied to each phase of the 3-phase motor. Accordingly, even when any one of the plurality of switching elements and the plurality of diodes has a short circuit failure, the three-phase motor can be driven with a certain degree of accuracy.

Here, the three-level inverter includes U-phase, V-phase, and W-phase first to fourth switching elements as the plurality of switching elements, and the U-phase, V-phase, and W-phase as the plurality of diodes. It has 1st-4th diodes and 1st-6th clamp diodes, and 1st, 2nd capacitors. The U-phase, V-phase, and W-phase first to fourth switching elements are connected in series in this order to the positive electrode line and the negative electrode line on the DC side. The first to fourth diodes of the U phase, V phase, and W phase are connected in parallel to the first to fourth switching elements of the U phase, V phase, and W phase, respectively. The U-phase, V-phase, and W-phase of the motor are connected to the connection points of the U-phase, V-phase, and W-phase second and third switching elements, respectively. The cathodes of the first, third, and fifth clamp diodes are connected to connection points of the U-phase, V-phase, and W-phase first and second switching elements, respectively. The cathodes of the second, fourth, and sixth clamp diodes are connected to the anodes of the first, third, and fifth clamp diodes, respectively. The connection points of the U-phase, V-phase, and W-phase third and fourth switching elements are connected to the anodes of the second, fourth, and sixth clamp diodes, respectively. The first and second capacitors are connected in series with the positive electrode line and the negative electrode line in this order. At the connection point (neutral point) of the first and second capacitors, the connection point of the first and second clamp diodes, the connection point of the third and fourth clamp diodes, and the fifth and sixth The connection point of the clamp diode is connected.

In the inverter device of the present invention, the control device includes the U-phase, V-phase, W-phase first to fourth switching elements and the U-phase, V-phase, W-phase first to fourth diodes and the When none of the first to sixth clamp diodes has a short circuit fault, the three-level voltage of three levels of high level, middle level, and low level is applied to each phase of the three-phase motor. The inverter may be controlled.

In this case, when any one of the first switching element of the U phase, the V phase, and the W phase and the first diode fails due to a short circuit, each phase of the three-phase motor has two levels of high level and low level. The three-level inverter may be controlled so that the voltage of 3 is applied. When any one of the U-phase, V-phase, and W-phase second switching elements and the second diode is short-circuited, a high-level voltage and a middle-level voltage of two levels are applied to each phase of the three-phase motor. The three-level inverter may be controlled to be applied.

When any one of the U-phase, V-phase, W-phase third switching element and the third diode has a short-circuit fault, each phase of the three-phase motor has a middle-level and low-level two-level voltage. The three-level inverter may be controlled so that When any one of the U-phase, V-phase, and W-phase fourth switching elements and the fourth diode is short-circuited, a high-level and low-level two-level voltage is applied to each phase of the three-phase motor. The three-level inverter may be controlled to be applied.

When any one of the first, third, and fifth clamp diodes has a short-circuit fault, the three-level inverter is configured to apply a two-level voltage of a middle level and a low level to each phase of the three-phase motor. May be controlled. When any one of the second, fourth, and sixth clamp diodes has a short-circuit fault, the three-level inverter is configured to apply a two-level voltage of high level or middle level to each phase of the three-phase motor. May be controlled.

It is a block diagram which shows the outline of a structure of the drive device 20 provided with the inverter apparatus as one Example of this invention. 5 is an explanatory diagram showing an example of a control mode setting routine executed by the ECU 30. FIG. It is explanatory drawing which shows an example of voltage Vu, Vv, Vw of each phase and current Iu, Iv, Iw when a normal mode is set to a control mode. Short circuit failure occurs in any of the switching elements Su1, Sv1, Sw1 and the diodes Du1, Dv1, Dw1, and the voltages Vu, Vv, Vw and the currents Iu, Iv, Iw of the respective phases when the HL mode is set as the control mode. It is explanatory drawing which shows an example. Short circuit failure occurs in any of the switching elements Su2, Sv2, Sw2 and the diodes Du2, Dv2, Dw2, and the voltages Vu, Vv, Vw and the currents Iu, Iv, Iw of the respective phases when the HM mode is set as the control mode. It is explanatory drawing which shows an example. FIG. 3 is an explanatory diagram showing an example of the voltages Vu, Vv, Vw and currents Iu, Iv, Iw of each phase when any of the clamp diodes Dc1, Dc3, Dc5 has a short circuit fault and the control mode is set to the ML mode. is there. It is a block diagram which shows the outline of a structure of the drive device 120 of a modification.

Next, modes for carrying out the present invention will be described using examples.

FIG. 1 is a configuration diagram showing an outline of a configuration of a drive device 20 including an inverter device as an embodiment of the present invention. The drive device of the embodiment is mounted on an electric vehicle or a hybrid vehicle, and as shown in the drawing, a traveling motor 22, an inverter 24 for driving the motor 22, and a battery connected to the inverter 24 via a power line 28. 26 and an electronic control unit (hereinafter, referred to as “ECU”) 30 that controls the inverter 24. Here, the "inverter device" mainly corresponds to the inverter 24 and the ECU 30.

The motor 22 is configured as a three-phase synchronous generator motor, and has a rotor in which a permanent magnet is embedded in a rotor core, and a stator in which a three-phase coil is wound around the stator core. The battery 26 is configured as, for example, a lithium ion secondary battery or a nickel hydrogen secondary battery.

The inverter 24 is configured as a neutral-point clamp type three-level inverter, and includes U-phase, V-phase, and W-phase switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4, and diodes Du1 to Du4, Dv1 to Dv4. , Dw1 to Dw4, clamp diodes Dc1 to Dc6, and capacitors C1 and C2. As the switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4, for example, IGBTs are used.

The U-phase switching elements Su1 to Su4 are connected in series to the positive electrode line 28p and the negative electrode line 28n of the power line 28 in this order. The U-phase switching elements Su1 to Su4 are respectively connected in parallel with U-phase diodes Du1 to Du4 (so that the negative line 28n side of the power line 28 to the positive line 28p side is in the forward direction). The U phase of the motor 22 is connected to the connection point of the U phase switching elements Su2, Su3. The cathode of the clamp diode Dc1 is connected to the connection point of the U-phase switching elements Su1 and Su2. The cathode of the clamp diode Dc2 is connected to the anode of the clamp diode Dc1. The connection point of the U-phase switching elements Su3 and Su4 is connected to the anode of the clamp diode Dc2.

The V-phase switching elements Sv1 to Sv4 are connected in series in this order to the positive electrode line 28p and the negative electrode line 28n of the power line 28. The V-phase switching elements Sv1 to Sv4 are respectively connected with V-phase diodes Dv1 to Dv4 in parallel (so that the negative line 28n side of the power line 28 to the positive line 28p side is in the forward direction). The V-phase of the motor 22 is connected to the connection point of the V-phase switching elements Sv2 and Sv3. The cathode of the clamp diode Dc3 is connected to the connection point of the V-phase switching elements Sv1 and Sv2. The cathode of the clamp diode Dc4 is connected to the anode of the clamp diode Dc3. The connection point of the V-phase switching elements Sv3 and Sv4 is connected to the anode of the clamp diode Dc4.

The W-phase switching elements Sw1 to Sw4 are connected in series to the positive electrode line 28p and the negative electrode line 28n of the power line 28 in this order. The W-phase switching elements Sw1 to Sw4 are respectively connected with W-phase diodes Dw1 to Dw4 in parallel (so that the negative line 28n side of the power line 28 to the positive line 28p side is in the forward direction). The W-phase of the motor 22 is connected to the connection point of the W-phase switching elements Sw2 and Sw3. The cathode of the clamp diode Dc5 is connected to the connection point of the W-phase switching elements Sw1 and Sw2. The cathode of the clamp diode Dc6 is connected to the anode of the clamp diode Dc5. The connection point of the W-phase switching elements Sw3 and Sw4 is connected to the anode of the clamp diode Dc6.

The capacitors C1 and C2 have the same rated capacity, and are connected in series in this order to the positive electrode line 28p and the negative electrode line 28n of the power line 28. The connection points of the capacitors C1 and C2 (neutral point NP) are connected to the connection points of the clamp diodes Dc1 and Dc2, the connection points of the clamp diodes Dc3 and Dc4, and the connection points of the clamp diodes Dc5 and Dc6. ..

Although not shown, the ECU 30 is configured as a microprocessor centered on a CPU, and includes, in addition to the CPU, a ROM for storing a processing program, a RAM for temporarily storing data, and an input/output port. Signals from various sensors are input to the ECU 30 via input ports. The signals input to the ECU 30 include, for example, the rotational position θm from the rotational position sensor 22a that detects the rotational position of the rotor of the motor 22 and the current sensors 22u and 22v that detect the current of each phase of the motor 22. The current Iu and Iv of each phase can be mentioned. Switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 and diodes Du1 to Du4, Dv1 to Dv4, Dw1 to Dw4 and clamp diodes Dc1 to Dc6 of the respective phases of the inverter 24 are supplied from temperature sensors (not shown). Each temperature can also be mentioned. Furthermore, the voltage Vb from the voltage sensor 26a that detects the voltage of the battery 26 and the current Ib from the current sensor 26b that detects the current of the battery 26 can also be mentioned.

Various control signals are output from the ECU 30 via the output port. As a signal output from the ECU 30, for example, a control signal to the switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 of each phase of the inverter 24 is output via the output port. The ECU 30 calculates the electrical angle θe and the rotational speed Nm of the motor 22 based on the rotational position θm of the rotor of the motor 22 from the rotational position sensor 22a, and the battery based on the current Ib of the battery 26 from the current sensor 26b. The storage ratio SOC of 26 is calculated.

In the drive device 20 of the embodiment configured in this way, the ECU 30 causes the switching elements Su1 to Su4, Sv1 to Sv4 of the inverter 24 by pulse width modulation control (PWM control) so that the motor 22 is driven by the torque command Tm*. Switching control of Sw1 to Sw4 is performed.

In the control of the inverter 24, first, assuming that the sum of the currents flowing in the respective phases of the motor 22 is 0, the electric angles θe of the motor 22 are used to calculate the currents Iu and Iv of the U phase and the V phase in the d-axis and q-axis. Coordinate conversion (three-phase to two-phase conversion) is performed on the axis currents Id and Iq. Then, the d-axis and q-axis current commands Id* and Iq* are set based on the torque command Tm* of the motor 22, and the d-axis and q-axis currents Id and Iq and the current commands Id* and Iq* are set. The d-axis and q-axis voltage commands Vd* and Vq* are set so that the difference is canceled. Then, using the electrical angle θe of the motor 22, the d-axis and q-axis voltage commands Vd*, Vq* are coordinate-converted into U-phase, V-phase, W-phase voltage commands Vu*, Vv*, Vw* (two-phase). -3 phase conversion). Then, based on the U-phase, V-phase, and W-phase voltage commands Vu*, Vv*, and Vw*, the PWM signals of the U-phase, V-phase, and W-phase switching elements Su1 to Su4, Sv1 to Sv4, and Sw1 to Sw4 are generated. Switching control of the switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 is performed using the generated PMW signals of the switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4.

Next, the operation of the driving device 20 of the embodiment thus configured, in particular, the switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 of each phase based on the voltage commands Vu*, Vv*, Vw* of each phase. A control mode setting process for generating the PWM signal and performing the switching control will be described. FIG. 2 is an explanatory diagram showing an example of a control mode setting routine executed by the ECU 30. This routine is repeatedly executed.

When the control mode setting routine of FIG. 2 is executed, each phase element of the inverter 24 (switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 and diodes Du1 to Du4, Dv1 to Dv4, Dw1 to Dw4 and clamps). It is determined whether any of the diodes Dc1 to Dc6) has a short circuit failure (step S100). This process can be performed, for example, by comparing the temperature from a temperature sensor (not shown) attached to each element of each phase of the inverter 24 with a threshold value. This is because thermal destruction due to overheating can be considered as a factor of a short circuit failure of each element of each phase of the inverter 24.

When it is determined in step S100 that none of the elements of each phase of the inverter 24 are short-circuited, the control mode is set to the normal mode (step S110), and this routine is ended. When the control mode is set to the normal mode, three phases of high level (H level), middle level (M level) and low level (L level) voltages of each phase are applied to each phase of the motor 22. Based on the voltage commands Vu*, Vv*, Vw*, PWM signals of the switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 of each phase are generated to perform switching control thereof.

Here, the relationship between ON/OFF of the U-phase switching elements Su1 to Su4 and the U-phase voltage Vu of the motor 22 will be described. When the switching elements Su1 and Su2 are turned on and the switching elements Su3 and Su4 are turned off, a current flows from the positive line 28p of the power line 28 to the U phase of the motor 22 via the switching elements Su1 and Su2. At this time, the potential of the U-phase input terminal of the motor 22 becomes substantially equal to the potential of the positive electrode line 28p of the power line 28, and the U-phase voltage Vu of the motor 22 becomes high level.

When the switching elements Su3, Su4 are turned on and the switching elements Su1, Su2 are turned off, a current flows from the U-phase input terminal of the motor 22 to the negative line 28n of the power line 28 via the switching elements Su3, Su4. At this time, the potential of the U-phase input terminal of the motor 22 becomes substantially equal to the potential of the negative line 28n of the power line 28, and the U-phase voltage Vu of the motor 22 becomes low level.

When the switching elements Su2, Su3 are turned on and the switching elements Su1, Su4 are turned off, from the connection point (neutral point NP) of the capacitors C1, C2 to the input terminal of the motor 22 via the clamp diode Dc1 and the switching element Su2. A current may flow, or a current may flow from the input terminal of the motor 22 to the connection point between the capacitors C1 and C2 via the switching element Su3 and the clamp diode Dc2. At this time, the potential of the U-phase input terminal of the motor 22 becomes substantially equal to the potential of the connection point of the capacitors C1 and C2, and the U-phase voltage Vu of the motor 22 becomes the middle level.

The same applies to the relationship between ON/OFF of the V-phase switching elements Sv1 to Sv4 and the V-phase voltage Vv of the motor 22, and the relationship between the ON/OFF of the W-phase switching elements Sw1 to Sw4 and the W-phase voltage Vw of the motor 22. ..

When it is determined in step S100 that one of the elements of each phase of the inverter 24 has a short circuit failure, it is determined which of each element of each phase of the inverter 24 has a failure (step S120). This process can be performed in the same manner (or collectively) as the process of step S100.

When it is determined in step S120 that one of the switching elements Su1, Sv1, Sw1 and the diodes Du1, Dv1, Dw1 has a short-circuit fault, the control mode is set to the HL mode (step S130), and this routine ends. To do. When the HL mode is set as the control mode, each phase of the motor 22 is applied based on the voltage command Vu*, Vv*, Vw* of each phase so that two levels of voltage of high level and low level are applied to each phase. PWM signals of the switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 are generated to perform switching control of these.

A case where the switching element Su1 has a short circuit fault will be described. At this time, when the switching element Su2 is turned on, current flows from the positive line 28p of the power line 28 to the U phase of the motor 22 via the switching elements Su1 and Su2, and the voltage Vu of the U phase of the motor 22 becomes high level. Become. When the switching elements Su3, Su4 are turned on, a current flows from the U-phase input terminal of the motor 22 to the negative line 28n of the power line 28 via the switching elements Su3, Su4, and the voltage Vu of the U-phase of the motor 22 becomes Become low level.

However, when the switching elements Su2, Su3 are turned on, the positive line 28p of the power line 28 and the connection point (the neutral point NP) of the capacitors C1, C2 are short-circuited via the switching elements Su1, Su2, Su3 and the clamp diode Dc2. Resulting in. Therefore, the U-phase voltage Vu of the motor 22 cannot be set to the middle level. The same can be considered when any one of the switching elements Sv1 and Sw1 and the diodes Du1, Dv1 and Dw1 has a short circuit failure. For this reason, when any one of the switching elements Su1, Sv1, Sw1 and the diodes Du1, Dv1, Dw1 has a short-circuit fault, the control mode is set to the HL mode. Accordingly, even when any one of the switching elements Su1, Sv1, Sw1 and the diodes Du1, Dv1, Dw1 has a short circuit failure, the motor 22 can be driven with a certain degree of accuracy.

When it is determined in step S120 that one of the switching elements Su2, Sv2, Sw2 and the diodes Du2, Dv2, Dw2 has a short-circuit fault, the control mode is set to the HM mode (step S140), and this routine ends. To do. When the HM mode is set as the control mode, the PWM signals of the switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 of the respective phases are applied so that the two-level voltages of the high level and the middle level are applied to the respective phases of the motor 22. Are generated to perform switching control of these.

A case where the switching element Su2 has a short circuit fault will be described. At this time, when the switching element Su1 is turned on, a current flows from the positive line 28p of the power line 28 to the U phase of the motor 22 via the switching elements Su1 and Su2, and the voltage Vu of the U phase of the motor 22 becomes high level. Become. When the switching element Su3 is turned on, current flows from the connection point (neutral point NP) of the capacitors C1 and C2 to the input terminal of the motor 22 via the clamp diode Dc1 and the switching element Su2, or the input terminal of the motor 22. Current flows through the switching element Su3 and the clamp diode Dc2 to the connection point of the capacitors C1 and C2, and the U-phase voltage Vu of the motor 22 becomes a middle level.

However, when the switching elements Su3, Su4 are turned on, the connection point (neutral point NP) of the capacitors C1, C2 and the negative line 28n of the power line 28 are short-circuited via the clamp diode Dc1 and the switching elements Su2, Su3, Su4. Resulting in. Therefore, the U-phase voltage Vu of the motor 22 cannot be set to the low level. The same can be considered when any one of the switching elements Sv2, Sw2 and the diodes Du2, Dv2, Dw2 has a short circuit failure. For this reason, when any one of the switching elements Su2, Sv2, Sw2 and the diodes Du2, Dv2, Dw2 has a short circuit fault, the control mode is set to the HM mode. Accordingly, even when any one of the switching elements Su2, Sv2, Sw2 and the diodes Du2, Dv2, Dw2 has a short circuit failure, the motor 22 can be driven with a certain degree of accuracy.

When it is determined in step S120 that one of the switching elements Su3, Sv3, Sw3 and the diodes Du3, Dv3, Dw3 has a short-circuit fault, the control mode is set to the ML mode (step S150), and this routine ends. To do. When the ML mode is set as the control mode, each phase of the motor 22 is applied based on the voltage commands Vu*, Vv*, Vw* of each phase so that a voltage of two levels of a middle level and a low level is applied to each phase. PWM signals of the switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 are generated to perform switching control of these.

A case where the switching element Su3 has a short circuit fault will be described. At this time, when the switching element Su2 is turned on, current flows from the connection point (neutral point NP) of the capacitors C1 and C2 to the input terminal of the motor 22 via the clamp diode Dc1 and the switching element Su2, or the motor 22 A current flows from the input terminal to the connection point of the capacitors C1 and C2 via the switching element Su3 and the clamp diode Dc2, and the U-phase voltage Vu of the motor 22 becomes a middle level. When the switching element Su4 is turned on, a current flows from the U-phase input terminal of the motor 22 to the negative line 28n of the power line 28 via the switching elements Su3, Su4, and the U-phase voltage Vu of the motor 22 is at a low level. become.

However, when the switching elements Su1, Su2 are turned on, the positive line 28p of the power line 28 and the connection point (neutral point NP) of the capacitors C1, C2 are short-circuited via the switching elements Su1, Su2, Su3 and the clamp diode Dc2. Resulting in. Therefore, the U-phase voltage Vu of the motor 22 cannot be set to the high level. The same can be considered when any of the switching elements Sv3, Sw3 and the diodes Du3, Dv3, Dw3 has a short circuit failure. For these reasons, when any one of the switching elements Su3, Sv3, Sw3 and the diodes Du3, Dv3, Dw3 has a short circuit failure, the control mode is set to the ML mode. As a result, even if any of the switching elements Su3, Sv3, Sw3 and the diodes Du3, Dv3, Dw3 has a short circuit failure, the motor 22 can be driven with a certain degree of accuracy.

When it is determined in step S120 that any of the switching elements Su4, Sv4, Sw4 and the diodes Du4, Dv4, Dw4 has a short-circuit fault, the control mode is set to the HL mode (step S160), and this routine is ended. To do. When the HL mode is set as the control mode, each phase of the motor 22 is applied based on the voltage command Vu*, Vv*, Vw* of each phase so that two levels of voltage of high level and low level are applied to each phase. PWM signals of the switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 are generated to perform switching control of these.

A case where the switching element Su4 has a short circuit fault will be described. At this time, when the switching elements Su1 and Su2 are turned on, current flows from the positive line 28p of the power line 28 to the U phase of the motor 22 via the switching elements Su1 and Su2, and the voltage Vu of the U phase of the motor 22 becomes high. Become a level. When the switching element Su3 is turned on, a current flows from the U-phase input terminal of the motor 22 to the negative line 28n of the power line 28 via the switching elements Su3 and Su4, and the voltage Vu of the U-phase of the motor 22 is at a low level. become.

However, when the switching elements Su2, Su3 are turned on, the connection point (neutral point NP) of the capacitors C1, C2 and the negative line 28n of the power line 28 are short-circuited via the clamp diode Dc1 and the switching elements Su2, Su3, Su4. Resulting in. Therefore, the U-phase voltage Vu of the motor 22 cannot be set to the middle level. The same can be considered when any of the switching elements Sv4, Sw4 and the diodes Du4, Dv4, Dw4 has a short circuit failure. For this reason, when any one of the switching elements Su4, Sv4, Sw4 and the diodes Du4, Dv4, Dw4 has a short-circuit fault, the control mode is set to the HL mode. As a result, even when any one of the switching elements Su4, Sv4, Sw4 and the diodes Du4, Dv4, Dw4 has a short circuit failure, the motor 22 can be driven with a certain degree of accuracy.

When it is determined in step S120 that any one of the clamp diodes Dc1, Dc3, Dc5 has a short-circuit fault, the control mode is set to the ML mode (step S170), and this routine ends. When the ML mode is set as the control mode, each phase of the motor 22 is applied based on the voltage commands Vu*, Vv*, Vw* of each phase so that a voltage of two levels of a middle level and a low level is applied to each phase. PWM signals of the switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 are generated to perform switching control of these.

A case where the clamp diode Dc1 has a short circuit fault will be described. At this time, if the switching elements Su2, Su3 are turned on, current may flow from the connection point (neutral point NP) of the capacitors C1, C2 to the input terminal of the motor 22 via the clamp diode Dc1 and the switching element Su2, or A current flows from the input terminal of 22 through the switching element Su3 and the clamp diode Dc2 to the connection point of the capacitors C1 and C2, and the U-phase voltage Vu of the motor 22 becomes the middle level. When the switching elements Su3, Su4 are turned on, a current flows from the U-phase input terminal of the motor 22 to the negative line 28n of the power line 28 via the switching elements Su3, Su4, and the U-phase voltage Vu of the motor 22 becomes Become low level.

However, when the switching elements Su1 and Su2 are turned on, the positive line 28p of the power line 28 and the connection point (neutral point NP) of the capacitors C1 and C2 are short-circuited via the switching element Su1 and the clamp diode Dc1. Therefore, the U-phase voltage Vu of the motor 22 cannot be set to the high level. The same can be considered when any one of the clamp diodes Dc3 and Dc5 has a short circuit failure. For this reason, when any of the clamp diodes Dc1, Dc3, Dc5 has a short circuit fault, the control mode is set to the ML mode. Accordingly, even when any of the clamp diodes Dc1, Dc3, Dc5 has a short circuit failure, the motor 22 can be driven with a certain degree of accuracy.

When it is determined in step S120 that any one of the clamp diodes Dc2, Dc4, Dc6 has a short circuit failure, the control mode is set to the HM mode (step S140), and this routine is ended. When the HM mode is set as the control mode, the PWM signals of the switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 of the respective phases are applied so that the two-level voltages of the high level and the middle level are applied to the respective phases of the motor 22. Are generated to perform switching control of these.

A case where the clamp diode Dc2 has a short circuit fault will be described. At this time, when the switching elements Su1 and Su2 are turned on, current flows from the positive line 28p of the power line 28 to the U phase of the motor 22 via the switching elements Su1 and Su2, and the voltage Vu of the U phase of the motor 22 becomes high. Become a level. When the switching elements Su2, Su3 are turned on, current flows from the connection point (neutral point NP) of the capacitors C1, C2 to the input terminal of the motor 22 via the clamp diode Dc1 and the switching element Su2, or the input terminal of the motor 22. Current flows to the connection point between the capacitors C1 and C2 via the switching element Su3 and the clamp diode Dc2, and the U-phase voltage Vu of the motor 22 becomes a middle level.

However, when the switching elements Su3, Su4 are turned on, the connection point (neutral point NP) of the capacitors C1, C2 and the negative line 28n of the power line 28 are short-circuited via the clamp diode Dc2 and the switching element Su4. Therefore, the U-phase voltage Vu of the motor 22 cannot be set to the low level. The same can be considered when any one of the clamp diodes Dc4 and Dc6 has a short circuit failure. For this reason, when any of the clamp diodes Dc2, Dc4, Dc6 has a short circuit failure, the HM mode is set as the control mode. Accordingly, even when any one of the clamp diodes Dc2, Dc4, Dc6 has a short circuit failure, the motor 22 can be driven with a certain degree of accuracy.

FIG. 3 is an explanatory diagram showing an example of the voltages Vu, Vv, Vw and the currents Iu, Iv, Iw of the respective phases when the normal mode is set as the control mode. As shown in the figure, the voltages Vu, Vv, Vw of each phase change at three levels of high level, middle level, and low level, and the currents Iu, Iv, Iw of each phase are sine shifted by 120 degrees. You can see that it is a wave.

FIG. 4 shows the voltage Vu, Vv, Vw and the current Iu of each phase when one of the switching elements Su1, Sv1, Sw1 and the diodes Du1, Dv1, Dw1 has a short-circuit fault and the control mode is set to the HL mode. It is explanatory drawing which shows an example of Iv, Iw. As shown in the figure, the voltages Vu, Vv, Vw of each phase change at two levels of high level and low level, and the currents Iu, Iv, Iw of each phase have more ripples than in the normal mode. However, it can be seen that the sine wave is shifted by 120 degrees. Therefore, even if any of the switching elements Su1, Sv1, Sw1 and the diodes Du1, Dv1, Dw1 has a short circuit failure, the motor 22 can be driven with a certain degree of accuracy. Further, even when any one of the switching elements Su4, Sv4, Sw4 and the diodes Du4, Dv4, Dw4 has a short-circuit fault, the control mode is set to the HL mode, and thus the motor 22 is similarly driven with a certain degree of accuracy. can do.

FIG. 5 shows that any one of the switching elements Su2, Sv2, Sw2 and the diodes Du2, Dv2, Dw2 has a short circuit fault and the voltages Vu, Vv, Vw and the current Iu of each phase when the HM mode is set as the control mode. It is explanatory drawing which shows an example of Iv, Iw. As shown in the figure, the voltages Vu, Vv, Vw of each phase are changed at two levels of high level and middle level, and the currents Iu, Iv, Iw of each phase are disturbed (distorted), It can be seen that the sine wave is shifted by 120 degrees without the occurrence of overcurrent in the short-circuit phase that causes dragging torque. Therefore, even when any one of the switching elements Su2, Sv2, Sw2 and the diodes Du2, Dv2, Dw2 has a short circuit failure, the motor 22 can be driven with a certain degree of accuracy. Further, even when any one of the clamp diodes Dc2, Dc4, Dc6 has a short circuit failure, the control mode is set to the HM mode, and thus the motor 22 can be driven with a certain degree of accuracy in the same manner.

FIG. 6 shows an example of the voltages Vu, Vv, Vw and the currents Iu, Iv, Iw of the respective phases when one of the clamp diodes Dc1, Dc3, Dc5 has a short-circuit fault and the control mode is set to the ML mode. It is an explanatory view shown. As shown in the figure, the voltages Vu, Vv, Vw of each phase change at two levels of the middle level and the low level, and the currents Iu, Iv, Iw of each phase are disturbed (distorted), It can be seen that the sine wave is shifted by 120 degrees without the occurrence of overcurrent in the short-circuit phase that causes dragging torque. Therefore, even when any one of the clamp diodes Dc1, Dc3, Dc5 has a short circuit failure, the motor 22 can be driven with a certain degree of accuracy. Further, even when any one of the switching elements Su3, Sv3, Sw3 and the diodes Du3, Dv3, Dw3 has a short circuit failure, the control mode is set to the ML mode, and thus the motor 22 is similarly driven with a certain degree of accuracy. can do.

In the drive device 20 of the embodiment described above, each phase element of the inverter 24 (switching elements Su1 to Su4, Sv1 to Sv4, Sw1 to Sw4 and diodes Du1 to Du4, Dv1 to Dv4, Dw1 to Dw4 and clamp diode Dc1). ~Dc6) when a short circuit failure occurs, the remaining elements other than the short circuit failure element are used, and any two levels of high level, middle level and low level are applied to each phase of the motor 22. The inverter 24 is controlled so that the voltage is applied. This allows the motor 22 to be driven with a certain degree of accuracy even when any one of the elements of each phase has a short circuit failure.

In the drive device 20 of the embodiment, as shown in FIG. 1, the inverter 24 has six clamp diodes Dc1 to Dc6. However, the six clamp diodes Dc1 to Dc6 of the inverter 24 may be replaced with six clamp switching elements. In this case, the six clamp switching elements may be switching-controlled according to the voltage (high level, middle level, low level) to be applied to the motor 22.

In the drive device 20 of the embodiment, as shown in FIG. 1, the inverter 24 has the capacitors C1 and C2 and further has the battery 26. However, the configuration may be as shown in the drive device 120 of the modified example of FIG. 7. The drive device 120 is the same as the drive device 20 of FIG. 1 except that the capacitors C1 and C2 of the inverter 24 are replaced with batteries 125 and 126 and the battery 26 is not provided. The batteries 125 and 126 have a rated capacity sufficiently larger than those of the capacitors C1 and C2 and are configured to be the same as each other. With such a configuration, it is possible to suppress fluctuations in the potential of the neutral point NP and suppress fluctuations in the middle-level voltage applied to the motor 22, as compared with those using the capacitors C1 and C2. You can

Correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem will be described. In the embodiment, the inverter 24 corresponds to a “three-level inverter” and the ECU 30 corresponds to a “control device”.

The correspondence between the main elements of the embodiment and the main elements of the invention described in the section of means for solving the problem is the same as the embodiment described in the section of the means for solving the problem. This is an example for specifically explaining the mode for carrying out the invention, and does not limit the elements of the invention described in the column of means for solving the problem. That is, the interpretation of the invention described in the column of means for solving the problem should be made based on the description in that column, and the embodiment is the invention of the invention described in the column of means for solving the problem. This is just a specific example.

The embodiments for carrying out the present invention have been described above with reference to the embodiments. However, the present invention is not limited to these embodiments, and various embodiments are possible within the scope not departing from the gist of the present invention. Of course, it can be implemented.

INDUSTRIAL APPLICABILITY The present invention can be used in the manufacturing industry of inverter devices.

20, 120 drive device, 22 motor, 22a rotational position sensor, 22u, 22v current sensor, 24 inverter, 26, 125, 126 battery, 26a voltage sensor, 26b current sensor, 28 power line, 28n negative line, 28p positive line, 30 electronic control unit (ECU), C1 and C2 capacitors, Dc1 to Dc6 clamp diodes, Du1 to Du6, Dv1 to Dv6, Dw1 to Dw6 diodes, Su1 to Su6, Sv1 to Sv6, Sw1 to Sw6 switching elements.

Claims (1)

A neutral point clamp type three-level inverter that has a plurality of switching elements and a plurality of diodes as each element of each phase and drives a three-phase motor,
A controller for controlling the three-level inverter so that three-level voltage is applied to each phase of the three-phase motor;
An inverter device comprising:
When any one of the elements of each of the phases has a short circuit failure, the controller uses two elements of each of the phases of the three-phase motor by using two elements of each phase of the three-phase motor. Controlling the three-level inverter so that the voltage of
Inverter device.