TW201910155A - Motor drive system of electric vehicle - Google Patents

Abstract

A motor drive system of an electric vehicle, used for driving an alternating current motor and comprising: a first inverter power module and a second inverter power module disposed in a manner of parallel connection; a direct current input end of the first inverter power module and a direct current input end of the second inverter power module are both electrically connected to an output end of a power battery of the electric vehicle; a first three-phase alternating current output end of the first inverter power module outputs a first three-phase alternating current to a first three-phase winding of the alternating current motor; and a second three-phase alternating current output end of the second inverter power module outputs a second three-phase alternating current to a second three-phase winding of the same alternating current motor. The motor drive system is low in cost, reliable and safe.

Description

Motor drive system for electric vehicles

The invention belongs to the technical field of AC motor drive control, and relates to a motor drive system and a fault detection method of an electric vehicle using a first inverter power module and a second inverter power module connected in parallel.

High-power AC motors (such as induction motors or permanent magnet synchronous motors) are widely used in electric vehicles and as drive motors. With the increasing popularity of electric vehicles, the market is power density, cost, reliability and safety of motor drive systems. Sexuality and other aspects put forward higher requirements. At present, a three-phase full-bridge inverter topology is generally used to drive the motor. For an electric vehicle with a large power demand, the power density of the motor drive system is high, and the power device used in the motor drive system is susceptible to the power device ( For example, the maximum allowable current limit of power switches such as IGBTs, the selection of power devices and the cost are not easy to control. From the perspective of product reliability design, the power device of the motor drive system is prone to heat generation due to switch switching, so its "working environment" is relatively poor. Power devices of three-phase full-bridge inverters in motor drive systems are prone to common failure modes such as overcurrent and overheating. Therefore, the reliability of the inverter module in the motor drive system is difficult to ensure. From the perspective of vehicle safety and application, if a traditional three-phase full-bridge inverter fails to switch normally if one bridge arm fails, the entire motor drive system will not work, resulting in the electric vehicle losing power, easily posing safety hazards and using by users. cause inconvenience. In view of this, it is necessary to propose a new type of motor drive system for electric vehicles.

It is an object of the present invention to disclose a solution that eliminates or at least mitigates the deficiencies described above that occur in prior art solutions. The object of the invention is also to achieve one or more of the following advantages: - reducing the power requirements of the power devices used in the inverter power module; - reducing the cost of the motor drive system; - improving the safety of use of the motor drive system; - Improve the reliability of the motor drive system; - Avoid the loss of power of the electric car due to the failure of the inverter power module. According to an aspect of the present invention, a motor drive system for an electric vehicle for driving an AC motor includes: a first inverter power module and a second inverter power module disposed in parallel; wherein The DC input end of the inverter power module and the DC input end of the second inverter power module are electrically connected to the output end of the power battery of the electric vehicle, and the first three-phase AC output end of the first inverter power module outputs a three-phase alternating current to the first three-phase winding of the alternating current motor, and a second three-phase alternating current output of the second inverter power module outputs the second three-phase alternating current to the second three-phase winding of the same alternating current motor. According to an embodiment of the present invention, in a motor drive system, the first inverter power module and the second inverter power module are the same inverter power modules. In an embodiment, the AC motor is a three-phase AC motor, and the first three-phase winding and the second three-phase winding are in-phase windings. In still another embodiment, the alternating current machine is a six-phase alternating current machine, and the first three-phase winding and the second three-phase winding are out-of-phase windings. According to still another embodiment of the present invention, in a motor drive system, a first sensor and a second sense are respectively disposed at corresponding positions in the first inverter power module and the second inverter power module. The motor drive system further includes a mutual calibration unit configured to compare the first signal obtained by the first sensor with the second signal obtained by the second sensor to determine A fault condition of the first inverter power module and the second inverter power module is described. In one example, the first sensor includes a first current sensor disposed on each phase of a first three-phase AC output of the first inverter power module, the second sensor including a setting a second current sensor on each phase of the second three-phase AC output terminal of the second inverter power module; corresponding to the same phase of the first three-phase AC output terminal and the second three-phase AC output terminal The first current sensor and the second current sensor are connected to the mutual calibration unit, the mutual calibration unit is further configured to correspond to the first current sensor and the second current on the same phase The first current signal and the second current signal respectively obtained by the sensors are compared with each other to determine a fault condition of the power switch on the bridge arm of the phase corresponding to the first current sensor and the second current sensor. In still another example, the first sensor includes a first voltage sensor disposed in the first inverter power module for measuring a DC bus voltage thereof, and the second sensor includes a second voltage sensor for measuring a DC bus voltage thereof in the second inverter power module; the first voltage sensor and the second voltage sensor being connected to the mutual school unit, the mutual The calibration unit is further configured to compare the first voltage signal and the second voltage signal respectively obtained by the first voltage sensor and the second voltage sensor with each other to determine the first inverter power module and the first The fault condition of the two inverter power modules. In still another example, the first sensor includes a first temperature sensor disposed in the first inverter power module for measuring a temperature of the first inverter power module, the second sense The detector includes a second temperature sensor disposed in the second inverter power module for measuring the temperature of the second inverter power module; the first temperature sensor and the second temperature sensor are connected To the mutual school unit, the mutual school unit is further configured to compare the first temperature signal and the second temperature signal respectively obtained by the first temperature sensor and the second temperature sensor with each other to determine The fault condition of the first inverter power module and the second inverter power module is described. In still another example, the first temperature sensor is separately set for each power switch in the first inverter power module, and is each of the second inverter power module of the second inverter power module. The power switch sets the second temperature sensor separately. In the motor drive system of any of the above embodiments, optionally, further comprising a motor controller and a gate drive unit; wherein the inter-calibration unit is coupled to the motor controller and in the mutual school The unit determines to return a fault signal to the motor controller when any one of the first inverter power module and the second inverter power module fails. A motor drive system according to still another embodiment of the present invention, wherein the first three-phase AC output is cut off when the first inverter power module fails, and the second inverter power module is The two-phase AC output terminal keeps outputting the second three-phase AC power; when the second inverter power module fails, the second three-phase AC output terminal is cut off, and the first inverter power module is A three-phase AC output maintains the output of the first three-phase AC. Specifically, the first inverter power module and the second inverter power module are modularly constructed. According to still another aspect of the present invention, a fault detection method for a motor drive system is provided, wherein the motor drive system is configured to drive an AC motor, comprising: a first inverter power module and a second inverter power mode disposed in parallel The DC input end of the first inverter power module and the DC input end of the second inverter power module are electrically connected to the output end of the power battery of the electric vehicle, and the first three of the first inverter power module The phase AC output terminal outputs the first three-phase AC power to the first three-phase winding of the AC motor, and the second three-phase AC output terminal of the second inverter power module outputs the second three-phase AC power to the same AC motor a second three-phase winding; wherein the first inverter power module and the second inverter power module are the same inverter power module; the fault detection method includes the steps of: acquiring the first a first signal in the inverter power module and a second signal in the second inverter power module, wherein the first signal and the second signal are the same type of signal; a signal Comparing the second signal with each other to determine if the fault condition of the power module of the first inverter and the second inverter power module. According to an embodiment of the present invention, the first signal is a first current signal collected from each phase of the first three-phase AC output of the first inverter power module, The second signal is a second current signal collected from each phase of the second three-phase AC output terminal of the second inverter power module; wherein, in the mutual comparison step, the corresponding phase on the same phase The first current signal ( i _fa , i _fb or i _fc ) and the second current signal ( i _{fa '} , i _{fb '} or i _{fc '} ) are compared with each other to determine a fault condition of the power switch on the bridge arm of the corresponding phase . When the first three-phase winding and the second three-phase winding are in-phase windings, in the mutual comparison step, the first current signal and the second current signal corresponding to the same phase are compared in size. When the first three-phase winding and the second three-phase winding are out-of-phase windings, in the mutual comparison step, the first current signal and the second current signal corresponding to the same phase are compared in size and sum vector Amplitude or angle comparison. According to still another aspect of the present invention, the first signal is a first voltage signal collected from a DC bus of the first inverter power module, and the second signal is from the a second voltage signal obtained by the DC bus of the second inverter power module; wherein, in the mutually comparing step, comparing the first voltage signal and the second voltage signal to each other to determine the first inverse Fault conditions of the variable power module and the second inverter power module. According to still another aspect of the present invention, the first signal is a first temperature signal collected from the first inverter power module, and the second signal is from the second inverse a second temperature signal obtained by the variable power module; wherein, in the mutually comparing step, comparing the first temperature signal and the second temperature signal to each other to determine the first inverter power module and the first The fault condition of the two inverter power modules. In the motor drive system of the present invention, the first inverter power module and the second inverter power module arranged in parallel are used, the power requirement for each inverter power module is reduced, and the inverter power mode is also reduced. The power requirements of the power devices used in the group, such as the maximum allowable current of the selected power switch can be reduced, the power switch is easy to select, and therefore the cost of the motor drive system is reduced; and the use of the motor drive system is safe and reliable. Sexuality is improved.

The invention will now be described more fully hereinafter with reference to the accompanying drawings in which FIG. However, the invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. In the following description, for the sake of clarity and conciseness of the description, all the various components shown in the drawings are not described in detail. The various components of the present invention are fully apparent to those skilled in the art, and the operation of many components is familiar and obvious to those skilled in the art. 1 is a schematic structural view of a motor drive system of an electric vehicle according to an embodiment of the present invention; and FIG. 2 is a schematic view showing the mutual operation principle of the motor drive system according to an embodiment of the present invention. The motor drive system 10 of an electric vehicle according to an embodiment of the present invention and the principle of its fault detection method will be described in detail below with reference to FIGS. 1 and 2. The motor drive system 10 is used to drive an AC motor 90 of an electric vehicle (including a pure electric vehicle and a hybrid vehicle), which mainly includes a first inverter power module 120 and a second inverter power module 120' disposed in parallel. The first inverter power module 120 and the second inverter power module 120' can respectively invert the DC input to generate a three-phase AC output, thereby driving the AC motor 90 to work, and the AC motor 90 can be three-phase AC. The motor can also be a six-phase AC motor. The stator windings inside the three-phase AC motor and the six-phase AC motor can have different arrangement modes. The specific arrangement of the stator windings inside the three-phase AC motor or the six-phase AC motor is not Restrictive. Specifically, the DC input end of the first inverter power module 120 is connected to the output end of the power battery 30 on the electric vehicle, and the DC input end of the second inverter power module 120' is also connected to the power battery 30 on the electric vehicle. An output terminal; wherein the DC bus L12a in the first inverter power module 120 is electrically connected to the positive pole of the power battery 30, and the DC bus L12b in the first inverter power module 120 is electrically connected to the negative pole of the power battery 30; The DC bus L12a' of the second inverter power module 120' is electrically connected to the positive pole of the power battery 30, and the DC bus L12b' of the second inverter power module 120' is electrically connected to the negative pole of the power battery 30. The DC input terminals of the first inverter power module 120 and the second inverter power module 120 ′ may be provided with a DC-Link capacitor (ie, DC coupling capacitor) Cd or the first inverter power module 120 . And the second inverter power module 120' is respectively provided with a DC-Link capacitor. The DC-Link capacitor Cd can be connected across the DC input ends of the first inverter power module 120 or the second inverter power module 120'. The first inverter power module 120 and the second inverter power module 120' respectively have an inverter unit formed mainly by six power switches. As shown in FIG. 1 , three parallel bridge arms are connected between the DC bus bars L12a and L12b of the first inverter power module 120 , and two power switches connected in series are arranged on each bridge arm, so that the power switch Q11, Q12, Q21, Q22, Q31, Q32 are arranged as shown in FIG. 1; three parallel bridge arms are connected between the DC bus bars L12a' and L12b' of the second inverter power module 120', each Two power switches connected in series are arranged on the bridge arms, so that the power switches Q11', Q12', Q21', Q22', Q31', Q32' are arranged as shown in FIG. The power switches Q11, Q12, Q21, Q22, Q31, Q32, Q11', Q12', Q21', Q22', Q31', Q32' may specifically but not limited to power switching devices such as IGBTs, and the specific selection is subject to the first The maximum allowable output current limit of the inverter power module 120 or the second inverter power module 120'. As shown in FIG. 1 , the motor drive system 10 further includes a motor controller 190 and a gate drive unit 170. The motor controller 190 can obtain a corresponding control signal from the vehicle controller of the electric vehicle, for example, the motor controller 190 can The control gate driving unit 170 outputs the gate driving signals Qg1, Qg2, Qg3, Qg4, Qg5, and Qg6 as shown in FIG. 2 to the first inverter power module 120 and the second inverter power module 120', thereby The drive power switch operates at a predetermined timing. Corresponding to the output ends of the first inverter power module 120 and the second inverter power module 120', each of which outputs three-phase alternating current (U1, V1, W1) and (U1', V1', W1'), The three-phase AC output end of the first inverter power module 120 outputs three-phase alternating current (U1, V1, W1) to one of the three-phase windings 910 of the AC motor 90, and the three phases of the second inverter power module 120' The AC output outputs three-phase alternating current (U1', V1', W1') to a further three-phase winding 920 of the AC motor 90. In one embodiment, the AC motor 90 is a three-phase AC motor, the three-phase winding 910 and the three-phase winding 920 are in-phase windings, three-phase alternating current (U1, V1, W1) and (U1', V1', W1') Electrically in phase, they can simultaneously provide superimposed three-phase AC inputs for the three-phase AC motor. For example, U1 and U2, V1 and V2, W1 and W2 correspond to the three-phase windings applied to the AC motor 90, respectively. The phase windings, that is, the phase U1 and the phase U1' are respectively connected to the first in-phase winding of the three-phase winding 910 and the three-phase winding 920, and the phase V1 and the phase V1' are respectively connected to the three-phase winding 910 and the three-phase winding 920 The two in-phase windings, phase W1 and phase W1', respectively connect the three-phase winding 910 and the third in-phase winding of the three-phase winding 920. Therefore, the power output of the first inverter power module 120 and the second inverter power module 120' can be outputted on the AC motor 90 in a superimposed manner, and the high power requirement of the AC motor 90 of the electric vehicle can be easily satisfied. At the same time, the power output requirement of each inverter power module can also be reduced. For example, the first inverter power module 120 and the second inverter power module are compared when only one inverter power module is provided. The power output of the 120' can be halved. Thus, for power devices such as power switches in the first inverter power module 120 and the second inverter power module 120' connected in parallel, the maximum allowable current can be reduced, the power switch can be easily selected, and the cost is relatively low. That is to say, the cost per inverter power module is greatly reduced, and the cost of the entire motor drive system 10 is also reduced. In still another embodiment, the AC motor 90 is a six-phase AC motor, the three-phase winding 910 and the three-phase winding 920 are out-of-phase windings, three-phase alternating current (U1, V1, W1) and (U1', V1', W1' Electrically, there is, for example, a phase difference of 30°, which can simultaneously provide a six-phase AC output for the six-phase AC motor. For example, U1, U2, V1, V2, W1, W2 are respectively applied to the AC motor 90. On each phase winding of the six-phase winding, the six-phase winding is formed by a three-phase winding 910 and a three-phase winding 920, so that U1, V1, and W1 respectively correspond to phases of the three-phase winding 910 of the six-phase winding connected to the AC motor 90. Upper, U2, V2, and W2 correspond to respective phases of the three-phase winding 920 connected to the six-phase winding of the AC motor 90. By providing the three-phase windings 910 and 920, the three-phase alternating current (U1, V1, W1) and (U1', V1', W1') can electrically electrically have a phase difference of, for example, 30°. Similarly, the first inverter power module 120 and the second inverter power module 120' can provide a superimposed power output for the six-phase AC motor, such that the first inverter power module 120 and the second are connected in parallel. The power device such as the power switch in the inverter power module 120' can reduce the maximum allowable current, and the power switch can be easily selected and the cost is relatively low. In an embodiment, the first inverter power module 120 and the second inverter power module 120 ′ have the same structure and device configuration, for example, the first inverter power module 120 and the second inverter power module. The internal circuit structure of 120' is the same, and the device configuration of the corresponding power device is also the same, for example, power switches Q11, Q12, Q21, Q22, Q31, Q32 and power switches Q11', Q12', Q21', Q22', Q31 ', Q32' have the same configuration. Since the first inverter power module 120 and the second inverter power module 120' are electrically connected to the same power battery 30 in parallel (that is, have the same DC input), the first inverter having the same structure and device configuration is obtained. The three-phase alternating current (U1, V1, W1) and (U1', V1', W1') respectively outputted by the power module 120 and the second inverter power module 120' have the same output power and the same voltage. During the actual operation, the first inverter power module 120 and the second inverter power module 120' will generate the same heat quantity (if there is no fault), the voltage between the DC bus lines L12a and L12b and the DC bus L12a. The voltage between 'and L12b' is also the same (if there is no fault). Even if the three-phase alternating current (U1, V1, W1) and (U1', V1', W1') have a phase difference of, for example, 30°, three-phase alternating current (U1, V1, W1) and three-phase alternating current (U1', V1) The current of each phase between ', W1') is in the case of considering the phase difference and the vector, there is a fixed correspondence between the currents of the corresponding phases between them (if there is no fault). Specifically, the three-phase alternating current (U1, V1, W1) and (U1', V1', W1') respectively outputted by the first inverter power module 120 and the second inverter power module 120' are electrically in phase. And when used to drive a three-phase AC motor 90, under normal conditions, the current magnitude and voltage of each phase between three-phase alternating current (U1, V1, W1) and three-phase alternating current (U1', V1', W1') The size, the phase angle, and the like are the same; for example, as shown in FIG. 2, in the case where the power switch does not malfunction, the transient current i _inv1 at a certain time is substantially equal to i _inv2 , and i _{fa is} substantially equal to i _{fa '} i _{fb is} substantially equal to i _fb′ , i _{fc is} substantially equal to i _fc′ , the transient voltage u _{A is} substantially equal to u _A′ , u _{B is} substantially equal to u _B′ , and u _{C is} substantially equal to u _C′ . The first inverter power module 120 and the second inverter power module 120' according to an embodiment of the invention are the same inverter power modules. That is, if the first inverter power module 120 is replaced with the first inverter power module 120, or the first inverter power module 120' is replaced with the second inverter power module 120' (if their software is used) The configuration does not change), the replaced motor drive system 10 has substantially the same output as the motor drive system 10 prior to replacement. Specifically, the first inverter power module 120 and the second inverter power module 120 ′ have, for example, the same circuit structure, device configuration (eg, corresponding power switch parameters are identical), and/or circuit parameters, and even the first The inverter power module 120 and the second inverter power module 120' have the same sensor or peripheral circuit configuration and the like. In the case that the hardware between the first inverter power module 120 and the second inverter power module 120 ′ is the same, the first inverter power module 120 and the second inverter power module 120 ′ can be implemented. Modular construction, easy mass production, economies of scale, and reduced production costs; and when repairs are required, the modular inverter power module can be used to replace the failed first inverter power module 120 or the second The inverter power module 120' reduces maintenance costs. It should be understood that even if the hardware between the first inverter power module 120 and the second inverter power module 120' is the same, the first inverter power module 120 and the second inverter power may be correspondingly required according to requirements. The module 120 ′ performs different software configurations in the motor controller 190 to provide gate driving signals with different timings for the first inverter power module 120 and the second inverter power module 120 ′, respectively, to achieve the first The three-phase alternating current output by the inverter power module 120 and the second inverter power module 120' respectively has a predetermined phase difference. In the motor drive system 10 according to the embodiment of the present invention, the first inverter power module 120 and the second inverter power module 120' are arranged in parallel to output three-phase alternating current to drive the same AC motor 90. As the backup power module of the first inverter power module 120, the first inverter power module 120 can be used as the standby power module of the second inverter power module 120'. That is, the first inverter power module 120 and the second inverter power module 120' serve as backup power modules with each other, but both simultaneously output corresponding power. In this way, when one of the first inverter power module 120 and the second inverter power module 120', for example, the power switch fails, the other inverter power module can continue to work, but only provides the AC motor 90. The output power is reduced, for example, to half of the original; however, in this case, the AC motor 90 can continue to operate under low power conditions, the electric vehicle does not lose power, and can support the "carrying mode" of the electric vehicle (for example, Continue driving under low-speed conditions), ensuring the basic functions of electric vehicles, and avoiding the inconvenience caused by anchoring to the user. In an embodiment, as shown in FIG. 1, the motor drive system 10 further includes a mutual calibration unit 150, and is also respectively at a corresponding position in the first inverter power module 120 and the second inverter power module 120'. a first sensor and a second sensor (not shown) are provided. In the case that the first inverter power module 120 and the second inverter power module 120' are working normally, the first sensing is performed. The second sensor and the second sensor can collect and feed back substantially the same signals (eg, current signals, voltage signals, and/or temperature signals) to the mutual calibration unit 150. The mutual school unit 150 is configured to compare the signal obtained by the first sensor with the signal obtained by the second sensor to determine the failure of the first inverter power module 120 and the second inverter power module 120 ′. Happening. The reciprocal unit 150 can be implemented by, for example, a comparator, and the specific implementation is not limited. The operation of the reciprocal unit 150 is illustrated by taking the first inverter power module 120 and the second inverter power module 120 ′ for simultaneously driving the three-phase AC motor as an example. In an embodiment, as shown in FIG. 2, the AC motor 90 is a three-phase AC motor, and the first sensor in the first inverter power module 120 includes three phases disposed in the first inverter power module 120. a current sensor on each phase of the AC output terminal (not shown), that is, a current sensor corresponding to each of the U1, V1, and W1 phases; similarly, the second inverter power module 120' The second sensor includes a current sensor (not shown) disposed on each phase of the three-phase AC output terminal of the second inverter power module 120', that is, corresponding to U1', V1', and W1. 'Three phases each set a current sensor. A current sensor corresponding to each of the three phases corresponding to U1, V1, and W1 and a current sensor corresponding to each of the U1', V1', and W1' phases are connected to the mutual school unit 150, thereby acquiring them instantaneously. The current data is fed back to the mutual calibration unit 150; for example, the current signals i _fa , i _{fb ,} and i _fc as shown in FIG. 2 are respectively collected by current sensors corresponding to the respective phases of U1, V1, and W1, and they are collected. Basically, the instantaneous currents of the three phases of U1, V1, and W1 are reflected; the current signals i _fa' , i _fb', and i _fc' are respectively collected by current sensors corresponding to the respective U1', V1', and W1' phases. And they basically reflect the instantaneous current magnitude of the three phases of U1', V1', and W1'. The mutual school unit 150 compares the current signals collected corresponding to the same phase with each other, for example, compares the current signals i _fa , i _fb and i _fc with the current signals i _{fa '} , i _{fb '} and i _{fc '} respectively, if i _Fa , i _fb, and i _fc are equal to the current signals i _fa' , i _{fb '} and i _{fc '} , respectively, or the difference between i _fa and i _fa' , i _fb and i _{fb '} , i _fc and i _{fc '} is less than or equal to The allowable difference magnitude determines that the power switches on the bridge arms of each phase of the first inverter power module 120 and the second inverter power module 120' are working normally, that is, the power switches Q11, Q12, Q21, and Q22. Q31, Q32 and power switches Q11', Q12', Q21', Q22', Q31', Q32' all work normally, and the first inverter power module 120 and the second inverter power module 120' work normally; Conversely, it is determined that the power switch on the arm corresponding to a phase fails or fails. For example, when i _{fa is} not equal to i _fa' , the power on the corresponding arm of the larger one of i _fa and i _fa' There is an overcurrent fault in the switch. In an example, other powers fed back by one of the first inverter power module 120 and the second inverter power module 120' may also be The stream signal is compared with the expected target value. For example, i _fa2 and i _{fa3 are} further _compared with the control expected target value. If the reflection is not normal, it indicates that the power switch Q11 and Q12 are faulty. Otherwise, the power can be determined. There is a fault in switches Q11' and Q12'. Therefore, through the mutual comparison unit 150, not only the faults of the first inverter power module 120 and the second inverter power module 120' can be found, but also the failed power switch in each inverter power module can be located, in particular The overcurrent fault of the power switch can be found in time. In still another embodiment, the first sensor of the first inverter power module 120 may include a voltage sense disposed in the first inverter power module 120 for measuring a voltage between the DC bus bars L12a and L12b. a detector (not shown) for instantaneously acquiring instantaneous voltages applied to the DC bus voltages L12a and L12b; similarly, the second sensor of the second inverter power module 120' may include settings a voltage sensor (not shown) for measuring a voltage between the DC busses L12a' and L12b' in the second inverter power module 120' for instantaneously acquiring the applied DC bus voltage Instantaneous voltage on L12a' and L12b'. The voltage sensors provided corresponding to the DC bus bars L12a and L12b and the voltage sensors provided corresponding to the DC bus bars L12a' and L12b' are connected to the mutual calibration unit 150, thereby feeding back their instantaneously acquired voltage data to the mutual calibration unit 150. The mutual calibration unit 150 can be configured to compare the voltage signals respectively obtained by the two voltage sensors with each other to determine a fault condition of the first inverter power module 120 and the second inverter power module 120 ′; for example, When the voltages obtained by the two different voltage sensors are not equal, or the difference exceeds the allowable predetermined value, one of the first inverter power module 120 and the second inverter power module 120' may be determined. A fault has occurred, for example, one of the larger voltages has failed. In a further embodiment, the first sensor includes a first temperature sensor disposed in the first inverter power module 120 for measuring the temperature of the first inverter power module 120, similarly, The second sensor includes a second temperature sensor disposed in the second inverter power module 120 ′ for measuring the temperature of the second inverter power module 120 ′; the first temperature sensor and the second temperature The sensor is connected to the mutual calibration unit 150, and the mutual calibration unit 150 is further configured to compare the first temperature signal and the second temperature signal respectively obtained by the first temperature sensor and the second temperature sensor with each other to determine the first A fault condition of the inverter power module 120 and the second inverter power module 120'. If the first temperature signal and the second temperature signal are not equal or the difference exceeds the allowable predetermined value, the one of the first inverter power module 120 and the second inverter power module 120' may be determined to be too high. For example, an overheating fault has occurred. In the first inverter power module 120, each of the power switches may be provided with a first temperature sensor; likewise, in the second inverter power module 120', one for each power switch is provided. Second temperature sensor. The first temperature signal and the second temperature sensor and the second temperature sensor respectively corresponding to the same power switch in the first inverter power module 120 and the second inverter power module 120' respectively collect the first temperature signal and the second temperature signal respectively The temperature signals are compared to determine which power switch in the inverter power module has an overheat fault and to achieve accurate positioning of the overheat fault. When the first inverter power module 120 and the second inverter power module 120' are used to drive the six-phase AC motor, the first inverter power module 120 and the second inverter power module are in normal operation. 120' will generate the same calorific value, the voltage between the DC bus lines L12a and L12b and the voltage between the DC bus lines L12a' and L12b' are also the same, therefore, it is also possible to pass the mutual calibration unit in the manner disclosed in the above embodiments. And a temperature sensor and/or a voltage sensor disposed in the first inverter power module 120 and the second inverter power module 120 ′ to determine the first inverter power module 120 and the second inverter power The fault condition of the module 120'. For the current mutual comparison mode, a current sensor can be disposed on the first inverter power module 120 and the second inverter power module 120' in the manner of the embodiment shown in FIG. 2, and the current signal i is synchronously collected. _Fa , i _fb and i _fc and current signals i _fa' , i _{fb '} and i _{fc '} , the mutual school unit 150 can compare i _fa and i _fa' , i _fb and i _{fb '} , i _fc and i _{fc '} transients Poor, the current vector of the two first inverter power module 120 and the second inverter power module 120' can also be compared, and the difference between the vector amplitude or the angle can also reflect the first inverter power module 120 or The fault condition of the power switch on the second inverter power module 120'. The current, voltage, and/or temperature, etc. of the parallel first inverter power module 120 and the second inverter power module 120' of the above embodiment can be measured to be compared with each other, thereby achieving mutual monitoring between the two. It is easy to find faults of the first inverter power module 120 and the second inverter power module 120' in time. It will be understood that at least one of the current sensor, the voltage sensor and the temperature sensor in the embodiment described above may be simultaneously disposed in the first inverter power module 120 and the second inverter power module 120'. Two, the comparison unit 150 combines their comparison results to determine the fault condition of the first inverter power module 120 and the second inverter power module 120'. The mutual school unit 150 may send a fault signal to the motor controller when determining that one of the first inverter power module 120 and the second inverter power module 120' has a fault (eg, an overcurrent fault or an overheat fault) 190. The motor controller 190 can enable the motor drive system 10 to perform power derating operation or shutdown based on the feedback of the fault signal, thereby achieving the purpose of system protection and safe operation. In the power derating operation, one of the first inverter power module 120 and the second inverter power module 120' fails even if one of the first inverter power module 120 and the second inverter power module 120' fails, and the other one can serve as a backup of the failure, providing the original half of the power output, ensuring Electric vehicles can continue to operate safely. For example, when the first inverter power module 120 fails, the first three-phase AC output terminal is cut off, and the second three-phase AC output terminal of the second inverter power module 120' maintains the output second. Three-phase alternating current (U1', V1', W1'), therefore, the driven AC motor power is halved; when the second inverter power module 120' fails, its second three-phase AC output is cut off, And the first three-phase AC output terminal of the first inverter power module 120 keeps outputting the first three-phase AC power (U1, V1, W1), and similarly, the driven AC motor power is halved. It will be understood that when any three-phase AC output of the first inverter power module 120 and the second inverter power module 120' is cut off, the six-phase AC motor they drive will become a three-phase drive. . It should be noted that, in the foregoing embodiment, only two of the inverter power modules, that is, the first inverter power module 120 and the second inverter power module 120 ′ are illustrated. In other embodiments, according to the communication. For the power demand of the motor, three or more inverter power modules can be arranged side by side in the motor drive system, for example, two first inverter power modules 120 and two second inverter power modules are configured. 120'. It will be understood that when a component is "connected" to another component, it can be directly connected to the other component or the intermediate component can be present. The above examples mainly illustrate the motor drive system of the electric vehicle of the present invention and its failure detecting method. Although only some of the embodiments of the present invention have been described, it will be understood by those skilled in the art that the present invention can be implemented in many other forms without departing from the spirit and scope thereof, for example, each of the inverter power modules. A voltage sensor that measures the phase voltage is set. The present examples and embodiments are to be considered as illustrative and not restrictive, and the invention may cover various modifications without departing from the spirit and scope of the invention as defined by the appended claims. With replacement.

10‧‧‧Motor drive system

90‧‧‧AC motor

120‧‧‧First Inverter Power Module

120'‧‧‧Second inverter power module

30‧‧‧Power battery

L12a, L12b, L12a’, L12b’‧‧‧ DC bus

Cd‧‧‧DC-Link capacitor

Q11, Q12, Q21, Q22, Q31, Q32‧‧‧ power switch

Q11', Q12', Q21', Q22', Q31', Q32'‧‧‧ power switch

190‧‧‧Motor Controller

170‧‧‧ gate drive unit

Qg1, Qg2, Qg3, Qg4, Qg5, Qg6‧‧‧ gate drive signals

910, 920‧‧‧ three-phase winding

U1, V1, W1, U1', V1', W1'‧‧‧ three-phase AC

i _inv1 , i _inv2 , i _fa , i _fa' , i _fb , i _{fb '} , i _fc , i _{fc '} ‧ ‧ transient current

u _A , u _A' , u _B , u _B' , u _C , u _C' ‧‧‧ Transient voltage

150‧‧‧ mutual school unit

The above and other objects and advantages of the present invention will be more fully understood from the aspects of the appended claims. 1 is a schematic structural view of a motor drive system of an electric vehicle according to an embodiment of the present invention. 2 is a schematic diagram showing the principle of mutual operation of a motor drive system according to an embodiment of the present invention.

Claims (18)

A motor drive system (10) for an electric vehicle for driving an AC motor (90), comprising: a first inverter power module (120) and a second inverter power module (120' arranged in parallel Wherein, the DC input end of the first inverter power module (120) and the DC input end of the second inverter power module (120') are electrically connected to the output end of the power battery (30) of the electric vehicle, The first three-phase AC output of the inverter power module (120) outputs the first three-phase alternating current (U1, V1, W1) to the first three-phase winding (910) of the alternating current motor, and the second inverter power The second three-phase AC output of the module (120') outputs a second three-phase alternating current (U1', V1', W1') to a second three-phase winding (920) of the same AC motor (90). The motor drive system (10) of claim 1, wherein the first inverter power module (120) and the second inverter power module (120') are the same as the hardware. Inverter power module. The motor drive system (10) of claim 1, wherein the AC motor (90) is a three-phase AC motor, the first three-phase winding (910) and the second three-phase winding (920) ) is the same phase winding. The motor drive system (10) of claim 1, wherein the AC motor (90) is a six-phase AC motor, the first three-phase winding (910) and the second three-phase winding (920) ) is an out-of-phase winding. The motor drive system (10) of claim 2, wherein the first inverter power module (120) and the second inverter power module (120') are respectively provided with a first a sensor and a second sensor; the motor drive system (10) further comprising a mutual calibration unit (150) configured to receive the first signal and the second obtained by the first sensor The second signals obtained by the sensors are compared with each other to determine fault conditions of the first inverter power module (120) and the second inverter power module (120'). The motor drive system (10) of claim 5, wherein the first sensor comprises each phase disposed on a first three-phase AC output end of the first inverter power module (120) a first current sensor, the second sensor comprising a second current sensor disposed on each phase of the second three-phase AC output of the second inverter power module (120'); corresponding to The first current sensor and the second current sensor on the same phase of the first three-phase alternating current output end and the second three-phase alternating current output end are connected to the mutual school unit (150), the mutual The school unit (150) is further configured to respectively correspond to the first current signal ( i _fa , i _fb or i _fc ) and the second obtained by the first current sensor and the second current sensor on the same phase The current signals ( i _fa' , i _{fb '} or i _{fc '} ) are compared with each other to determine a fault condition of the power switch on the bridge arm of the phase corresponding to the first current sensor and the second current sensor. The motor drive system (10) of claim 5, wherein the first sensor comprises a first transformer power module (120) for measuring a DC bus voltage thereof. a voltage sensor, the second sensor includes a second voltage sensor disposed in the second inverter power module (120') for measuring a DC bus voltage thereof; the first voltage sense a detector and a second voltage sensor are coupled to the inter-calibration unit (150), the inter-calibration unit (150) being further configured to obtain the first voltage sensor and the second voltage sensor, respectively The first voltage signal and the second voltage signal are compared with each other to determine a fault condition of the first inverter power module (120) and the second inverter power module (120'). The motor drive system (10) of claim 5, wherein the first sensor comprises a first inverter power module (120) for measuring a first inverter power mode. a first temperature sensor of the temperature of the group (120), the second sensor comprising a second inverter power module (120') for measuring the second inverter power module (120') a second temperature sensor of the temperature; the first temperature sensor and the second temperature sensor are coupled to the mutual school unit, the inter-calibration unit (150) is further configured to The first temperature signal and the second temperature signal respectively obtained by the temperature sensor and the second temperature sensor are compared with each other to determine the first inverter power module (120) and the second inverter power module ( 120') fault condition. The motor drive system (10) of claim 8, wherein the first temperature sensor is separately provided for each of the first inverter power modules (120), which is a second Each of the power switches of the inverter power module second inverter power module (120') is respectively provided with the second temperature sensor. The motor drive system (10) of any one of claims 5 to 9, further comprising a motor controller (190) and a gate drive unit (170); wherein the mutual school unit ( 150) coupled to the motor controller (190) and determining, in the mutual rectification unit (150), the first inverter power module (120) and the second inverter power module (120') Any one of the faults is fed back to the motor controller (190). The motor drive system (10) of claim 1 or 2, wherein the first three-phase AC output terminal is disconnected when the first inverter power module (120) fails, And the second three-phase AC output end of the second inverter power module (120') keeps outputting the second three-phase alternating current (U1', V1', W1'); the second inverter power module ( 120') when the fault occurs, the second three-phase AC output is cut off, and the first three-phase AC output of the first inverter power module (120) keeps outputting the first three-phase alternating current (U1, V1) , W1). The motor drive system (10) of claim 2, wherein the first inverter power module (120) and the second inverter power module (120') are modularly constructed . A fault detecting method for detecting a motor driving system according to claim 2, comprising the steps of: simultaneously acquiring a first signal and a second inverter in the first inverter power module (120) a second signal in the power module (120'), wherein the first signal and the second signal are signals of the same type; and comparing the first signal and the second signal to determine The fault condition of the first inverter power module (120) and the second inverter power module (120'). The fault detection method of claim 13, wherein the first signal is obtained from each phase of the first three-phase AC output end of the first inverter power module (120). a current signal, the second signal being a second current signal collected from each phase of the second three-phase AC output of the second inverter power module (120'); wherein, in the comparison with each other In the step, the first current signal ( i _fa , i _fb or i _fc ) corresponding to the same phase and the second current signal ( i _fa′ , i _fb′ or i _fc′ ) are compared with each other to determine a corresponding phase. The fault condition of the power switch on the bridge arm. The fault detecting method according to claim 14, wherein when the first three-phase winding (910) and the second three-phase winding (920) are in-phase windings, in the mutual comparison step, The first current signal ( i _fa , i _fb or i _fc ) corresponding to the same phase and the second current signal ( i _{fa '} , i _{fb '} or i _{fc '} ) are compared for size. The fault detecting method according to claim 14, wherein when the first three-phase winding (910) and the second three-phase winding (920) are out-of-phase windings, in the mutual comparison step, Comparing the first current signal ( i _fa , i _fb or i _fc ) and the second current signal ( i _fa' , i _{fb '} or i _{fc '} ) on the same phase for size comparison, vector magnitude or angle comparison . The fault detection method of claim 13, wherein the first signal is a first voltage signal collected from a DC bus of the first inverter power module (120), and the second The signal is a second voltage signal collected from the DC bus of the second inverter power module (120'); wherein, in the mutually comparing step, the first voltage signal and the second voltage signal are performed Comparing with each other to determine a fault condition of the first inverter power module (120) and the second inverter power module (120'). The fault detection method of claim 13, wherein the first signal is a first temperature signal collected from the first inverter power module (120), and the second signal is a slave signal. The second inverter power module (120') collects the obtained second temperature signal; wherein, in the mutually comparing step, comparing the first temperature signal and the second temperature signal with each other to determine the The fault condition of the first inverter power module (120) and the second inverter power module (120').