Fault-tolerant control method, electronic equipment and computer readable storage medium

Abstract

The invention relates to the field of motor control, in particular to a fault-tolerant control method, electronic equipment for implementing the method and a computer readable storage medium. The method comprises the following steps of determining a voltage vector controllable range which can be used for controlling the stator voltage of the motor according to the type of a short-circuit bridge arm in response to a detected single-bridge-arm short-circuit fault of an inverter used for driving the alternating current motor; converting the voltage vector controllable range into a corresponding rotor angle controllable range; when the motor rotor angle is out of the rotor angle controllable range, controlling the AC motor to enter an active short-circuit state; and when the rotor angle of the motor is in the rotor angle controllable range, controlling the alternating current motor to output target torque by using current closed-loop control and discontinuous pulse width modulation, so that the average torque output by the alternating current motor in one electric period reaches an expected value.

Description

Technical Field

[0001] The present application relates to the field of motor control, and more particularly to a fault-tolerant control method, an electronic device for implementing the method, and a computer-readable storage medium. Background Art

[0002] Single-drive new energy vehicles have extremely high requirements for the safety and reliability of the electric drive system. In order to ensure that the vehicle can still drive or park safely when the electric drive system fails, the system must have strong fault tolerance. At present, new energy vehicles widely use three-phase AC motors (such as permanent magnet synchronous motors, asynchronous motors, synchronous reluctance motors, etc.) and are driven by three-phase full-bridge inverters. According to existing data, the inverter failure rate in the electric drive system is significantly higher than the motor winding failure rate, among which the inverter switch tube short circuit failure is the most common.

[0003] In the existing solutions, the common method to deal with inverter short-circuit faults is active short circuit (ASC), that is, if the upper bridge arm is short-circuited, the upper bridge arm three-phase ASC is executed, and if the lower bridge arm is short-circuited, the lower bridge arm three-phase ASC is executed. This solution can prevent the fault from further expanding and ensure that the system is in a relatively safe state. However, the system cannot perform torque control in the ASC state. For single-drive vehicles, this means power loss and inability to achieve safe parking or short-distance driving. Some solutions attempt to achieve fault-tolerant control by modifying the inverter topology (for example, adding a fuse to isolate the faulty bridge arm, and then using the remaining phase bridge arm to control the motor), but this will increase costs and introduce new device failure risks.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present application, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] In order to solve or at least alleviate one or more of the above problems, the present application provides a fault-tolerant control method, an electronic device implementing the method, and a computer-readable storage medium, which can fully utilize the remaining healthy power devices to achieve capacitor fault control and improve the availability of the electric drive system without changing the hardware structure of the motor and inverter and without adding additional devices.

[0006] According to a first aspect of the present application, a fault-tolerant control method is provided, the method comprising the following steps: in response to detecting a single-arm short-circuit fault in an inverter for driving an AC motor, determining a voltage vector controllable range that can be used to control the motor stator voltage according to the type of the short-circuited bridge arm; converting the voltage vector controllable range into a corresponding rotor angle controllable range; when the motor rotor angle is outside the rotor angle controllable range, controlling the AC motor to enter an active short-circuit state; and when the motor rotor angle is within the rotor angle controllable range, controlling the AC motor to output a target torque using current closed-loop control and discontinuous pulse width modulation, so that the average torque output by the AC motor within one electrical cycle reaches a desired value.

[0007] As an alternative or supplement to the above scheme, in a fault-tolerant control method according to an embodiment of the present application, the controllable range of the voltage vector that can be used to control the stator voltage of the motor is determined according to the type of short-circuited bridge arm, including: if the upper bridge arm of phase A is short-circuited, the controllable range of the voltage vector is determined to be [-π / 3, π / 3]; if the lower bridge arm of phase A is short-circuited, the controllable range of the voltage vector is determined to be [2π / 3, 4π / 3]; if the upper bridge arm of phase B is short-circuited, the controllable range of the voltage vector is determined to be [π / 3, π]; if the lower bridge arm of phase B is short-circuited, the controllable range of the voltage vector is determined to be [4π / 3, 2π]; if the upper bridge arm of phase C is short-circuited, the controllable range of the voltage vector is determined to be [π, 5π / 3]; if the lower bridge arm of phase C is short-circuited, the controllable range of the voltage vector is determined to be [0, 2π / 3].

[0008] As an alternative or supplement to the above solution, the fault-tolerant control method according to an embodiment of the present application further includes: determining the steady-state quadrature-axis current i of the AC motor in the active short-circuit state based on the motor parameters and the motor operating state. q_ASC and the steady-state direct-axis current i d_ASC ; and according to the torque formula, determine the braking torque T output by the AC motor in the active short-circuit state em_ASC .

[0009] As an alternative or supplement to the above scheme, the fault-tolerant control method according to an embodiment of the present application further includes: setting a transition angle range at the end of the controllable range of the rotor angle; and when the motor rotor angle is within the transition angle range, controlling the current to the steady-state quadrature-axis current i by using current closed-loop control. q_ASC and the steady-state direct-axis current i d_ASC .

[0010] As an alternative or supplement to the above solution, the fault-tolerant control method according to an embodiment of the present application also includes: determining the target torque according to the proportion of the rotor angle range of the AC motor outputting the target torque to the entire electrical cycle.

[0011] As an alternative or supplement to the above solution, in a fault-tolerant control method according to an embodiment of the present application, the target torque is determined as follows:

[0012]

[0013] Among them, θ * is the length of the rotor angle range within which the AC motor outputs the target torque, T em_ASC is the braking torque output by the AC motor in the active short-circuit state, T em_avg is the expected value of the average torque.

[0014] As an alternative or supplement to the above solution, in a fault-tolerant control method according to an embodiment of the present application, the θ * is 2π / 3.

[0015] As an alternative or supplement to the above solution, in a fault-tolerant control method according to an embodiment of the present application, the θ * is the difference between 2π / 3 and the length of the transition angle range.

[0016] As an alternative or supplement to the above solution, the fault-tolerant control method according to an embodiment of the present application further includes: determining the quadrature-axis current command value according to the target torque, the motor speed and the bus voltage. and direct axis current command value Using current closed loop control and Convert to quadrature axis voltage command value and direct-axis voltage command value

[0017] As an alternative or supplement to the above scheme, in a fault-tolerant control method according to an embodiment of the present application, using current closed-loop control and discontinuous pulse width modulation to control the AC motor to output a target torque includes: using the discontinuous pulse width modulation to convert the quadrature axis voltage command value and the direct-axis voltage command value converting the AC motor into a pulse width modulation signal; and sending the pulse width modulation signal to the inverter to drive the AC motor to output the target torque.

[0018] As an alternative or supplement to the above solution, in a fault-tolerant control method according to an embodiment of the present application, converting the voltage vector controllable range into a corresponding rotor angle controllable range includes: determining an angle θ between the stator voltage vector and the direct axis v ,in The rotor angle controllable range is determined as the voltage vector controllable range and the included angle θ v The difference between .

[0019] As an alternative or supplement to the above scheme, in a fault-tolerant control method according to an embodiment of the present application, the quadrature-axis current command value is determined according to the target torque, the motor speed and the bus voltage. and direct axis current command value The invention comprises: judging whether the AC motor will enter a weak magnetic field region according to the target torque, the motor speed and the bus voltage; in response to judging whether the AC motor will enter the weak magnetic field region, determining according to the maximum torque voltage ratio control strategy and In response to determining that the current will not enter the field weakening region, the maximum torque current ratio control strategy is used to determine and

[0020] According to the second aspect of the present application, an electronic device is provided, comprising: a memory; a processor; and a computer program stored on the memory and executable on the processor, wherein the execution of the computer program enables any one of the fault-tolerant control methods described in the first aspect of the present application to be executed.

[0021] As an alternative or supplement to the above solution, the electronic device according to an embodiment of the present application is a vehicle.

[0022] According to a third aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium comprises instructions, and wherein the instructions, when run, execute any one of the fault-tolerant control methods described in the first aspect of the present invention.

[0023] According to the fault-tolerant control scheme of one or more embodiments of the present application, the desired average torque can be output under the premise of not changing the hardware structure of the motor and the inverter and not increasing the additional cost, thereby solving the problem that the vehicle cannot continue to output power and cannot achieve safe side parking when a single bridge arm short circuit fault occurs. Specifically, the scheme proposes to switch two control strategies within one electrical cycle: when the rotor angle is outside the controllable range, it switches to the ASC state to ensure system safety and prevent the fault from further expanding; when the rotor angle is within the controllable range, current closed-loop control and discontinuous pulse width modulation are used to control the motor to output the target torque so that the average torque reaches the expected value. This dual-mode control strategy, on the one hand, uses the remaining healthy power devices to output effective torque in part of the electrical cycle, and on the other hand, maintains the ASC state in the remaining time to ensure safety, which not only improves the reliability and safety of the electric drive system under fault conditions, but also ensures the stability of the motor performance, thereby improving the fault tolerance and operation safety of new energy vehicles in the face of inverter failures. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or other aspects and advantages of the present application will become clearer and easier to understand through the following description of various aspects in conjunction with the accompanying drawings, in which the same or similar units are represented by the same reference numerals. In the accompanying drawings:

[0025] Figure 1 is a schematic flow chart of a fault-tolerant control method 10 according to one or more embodiments of the present application;

[0026] Figures 2A-2F The equivalent circuit diagram of each bridge arm of the three-phase full-bridge inverter when short-circuited and the corresponding voltage vector controllable range are shown respectively;

[0027] Figure 3 shows a schematic waveform diagram of the motor output torque under the fault-tolerant control method according to an embodiment of the present application;

[0028] Figure 4 is a schematic flow chart of a fault-tolerant control method 40 according to one or more embodiments of the present application;

[0029] Figure 5 A schematic diagram showing the relationship between time and rotor angle according to an embodiment of the present application is shown;

[0030] Figure 6 is a schematic block diagram of an electronic device 60 according to one or more embodiments of the present application. DETAILED DESCRIPTION

[0031] The description of the following specific embodiments is merely exemplary in nature and is not intended to limit the disclosed technology or the application and use of the disclosed technology. In addition, it is not intended to be bound by any express or implied theory presented in the aforementioned technical field, background technology or the following specific embodiments.

[0032] In the following detailed description of the embodiments, many specific details are set forth in order to provide a more thorough understanding of the disclosed technology. However, it is apparent to one of ordinary skill in the art that the disclosed technology can be practiced without these specific details. In other instances, well-known features are not described in detail to avoid unnecessarily complicating the description.

[0033] Terms such as "comprising" and "including" indicate that in addition to the units and steps directly and clearly stated in the specification, the technical solution of the present application does not exclude the situation of having other units and steps that are not directly or clearly stated. Terms such as "first" and "second" do not indicate the order of units in terms of time, space, size, etc., but are only used to distinguish between units.

[0034] Hereinafter, various exemplary embodiments according to the present application will be described in detail with reference to the accompanying drawings.

[0035] Referring to the accompanying drawings, Figure 1 is a schematic flow chart of a fault-tolerant control method 10 according to one or more embodiments of the present application.

[0036] like Figure 1 As shown, in step 110, in response to detecting a single-bridge arm short-circuit fault in an inverter for driving an AC motor, a controllable range of a voltage vector that can be used to control the stator voltage of the motor is determined according to the type of the short-circuited bridge arm.

[0037] It should be noted that the AC motor in the present solution can be a synchronous motor such as a permanent magnet synchronous motor, a synchronous reluctance motor, etc. In order to briefly explain the principle of the present solution, the implementation of the fault-tolerant control scheme 10 will be introduced below by taking a three-phase AC motor and a three-phase full-bridge inverter as examples. It should be noted that the fault-tolerant control scheme according to the present application can be applied to other types of AC motors (for example, five-phase AC motors) and other types of inverters with the same or similar principles, and the examples and implementation methods shown should be regarded as illustrative rather than restrictive.

[0038] The three-phase full-bridge inverter is composed of six bridge arms, namely, the upper bridge arm of phase A, the lower bridge arm of phase A, the upper bridge arm of phase B, the lower bridge arm of phase B, the upper bridge arm of phase C, and the lower bridge arm of phase C. Each bridge arm includes a switch device (for example, IGBT or MOSFET) and a diode device, and the short-circuit faults of these devices may cause the bridge arm to short-circuit. For example, the MOSFET device may have a drain-source (DS) short-circuit, and the IGBT device may have a collector-emitter (CE) short-circuit.

[0039] As shown in step 110, the triggering condition of the fault-tolerant control method 10 is "detecting a single-arm short-circuit fault in the inverter used to drive the AC motor", that is, a short-circuit fault occurs in one of the upper bridge arm of phase A, the lower bridge arm of phase A, the upper bridge arm of phase B, the lower bridge arm of phase B, the upper bridge arm of phase C, and the lower bridge arm of phase C. In other words, the fault-tolerant control method 10 is executed when it has been determined through a certain fault detection mechanism that a single-arm short-circuit fault occurs in the inverter. The fault detection mechanism for the inverter can be based on a detection mechanism known in the art, and the present application does not specifically limit this.

[0040] In AC motor control, voltage vector control is a commonly used method that adjusts the torque and speed of the motor by controlling the voltage vector output by the inverter to the stator winding of the motor. In voltage vector control, the output voltage of the inverter can be expressed as a series of voltage vectors (for example, voltage vector V 0 -V 7). When the inverter is operating normally, all voltage vectors can be used. However, once a single bridge arm short circuit fault occurs, some voltage vectors will not be generated due to the failure of the corresponding switching device. Step 110 is intended to determine the range of voltage vectors that the inverter can still generate under the single bridge arm short circuit fault state, that is, the controllable range of the voltage vector. This voltage vector controllable range is not fixed, but depends on the specific fault bridge arm type. For example, for a three-phase full-bridge inverter, a short circuit of the upper bridge arm of phase A, a short circuit of the lower bridge arm of phase A, a short circuit of the upper bridge arm of phase B, a short circuit of the lower bridge arm of phase B, a short circuit of the upper bridge arm of phase C, or a short circuit of the lower bridge arm of phase C will cause different voltage vectors to be unavailable, thereby generating different voltage vector controllable ranges. Therefore, it is necessary to determine the corresponding voltage vector controllable range according to the type of fault bridge arm (that is, which bridge arm is short-circuited) to provide a basis for subsequent control strategies.

[0041] Figures 2A-2F The equivalent circuit diagrams of the three-phase full-bridge inverter when each bridge arm is short-circuited and the corresponding voltage vector controllable range are shown respectively.

[0042] For a three-phase full-bridge inverter, eight voltage vectors V are usually used. 0 -V 7 To represent the output voltage state of the inverter, where V 0 and V 7 is the zero vector, V 1 -V 6 There are six non-zero vectors. By combining and modulating these eight vectors, the required output voltage can be synthesized to control the motor stator voltage. Under normal circumstances, all eight vectors can be used. However, when a single bridge arm short circuit fault occurs, some voltage vectors will be unavailable. For example, when the upper bridge arm is short-circuited, the voltage vector that relies on the conduction of the upper bridge arm will not be realized; when the lower bridge arm is short-circuited, the vector that relies on the conduction of the lower bridge arm will also fail. In addition, the use of zero vectors is also limited: when the upper bridge arm is short-circuited, only the zero vector V 7 ; When the lower bridge arm is short-circuited, only the zero vector V can be used 0 .

[0043] like Figure 2A As shown in Figure 1, when the upper bridge arm of phase A is short-circuited, the voltage vector containing the conduction state of the upper bridge arm of phase A cannot be used. Therefore, the available voltage vector is limited to V 4 、V 5 、V 6 and V 7 , the corresponding voltage vector controllable range is [-π / 3,π / 3], which means that the inverter can only control the motor stator voltage within this range. Figure 2B-2F, if the lower bridge arm of phase A is short-circuited, the corresponding voltage vector controllable range is [2π / 3,4π / 3]; if the upper bridge arm of phase B is short-circuited, the corresponding voltage vector controllable range is [π / 3,π]; if the lower bridge arm of phase B is short-circuited, the corresponding voltage vector controllable range is [4π / 3,2π]; if the upper bridge arm of phase C is short-circuited, the corresponding voltage vector controllable range is [π,5π / 3]; if the lower bridge arm of phase C is short-circuited, the corresponding voltage vector controllable range is [0,2π / 3]. It can be seen that for a single bridge arm short-circuit fault of a three-phase full-bridge inverter, there is still a voltage vector controllable range of 2π / 3 in a 2π electrical cycle.

[0044] In step 120, the voltage vector controllable range is converted into a corresponding rotor angle controllable range.

[0045] As mentioned above, the voltage vector control strategy adjusts the torque and speed of the motor by controlling the voltage vector output by the inverter to the stator winding of the motor. Therefore, after determining the controllable range of the voltage vector, it can be converted into the corresponding controllable range of the rotor angle. The purpose of this conversion is to convert the constraints of the voltage space into the constraints of the motor's rotational motion angle, so that the subsequent control strategy can decide which control mode to adopt based on the actual rotor angle of the motor.

[0046] The conversion process is based on the principle of motor vector control and needs to consider the relationship between the stator voltage vector angle and the rotor position angle. In one possible implementation, the A axis in the three-phase coordinate system is used as the reference axis. The angle θ between the stator voltage vector and the A axis is us That is, the angle between the stator voltage vector and the rotor magnetic field direct axis (d axis) and the A axis. e That is the rotor position angle. In order to obtain the rotor position angle θ e , it is necessary to introduce the angle θ between the stator voltage vector angle and the d-axis v , and its calculation formula is:

[0047]

[0048] in, and They are the quadrature axis (q-axis) voltage command value and the direct axis (d-axis) voltage command value in the dq coordinate system respectively. and The steps of determining will be described in detail below.

[0049] Rotor position angle θ e It can be calculated by the following formula:

[0050] θ e =θ us -θ v

[0051] It should be noted that the angle θ of each stator voltage vector in the controllable range of the voltage vector in step 110 is us The corresponding rotor position angle θ e The set of constitutes the controllable range of the rotor angle in step 120. For example, as described above, when the upper bridge arm of phase A is short-circuited, the controllable range of the voltage vector is [-π / 3, π / 3], so the corresponding controllable range of the rotor angle can be expressed as [-π / 3-θ v ,π / 3-θ v ], where θ v Depends on voltage command value and

[0052] After obtaining the controllable range of the rotor angle, different control modes can be switched according to whether the current motor rotor angle is within the controllable range of the rotor angle. Specifically, in step S130, when the motor rotor angle is outside the controllable range of the rotor angle, the AC motor is controlled to enter the ASC state; when the motor rotor angle is within the controllable range of the rotor angle, the AC motor is controlled to output the target torque using current closed-loop control and discontinuous pulse width modulation, so that the average torque output by the AC motor in one electrical cycle reaches the expected value. In the following, the above two control modes are referred to as "ASC control" and "torque output current loop control" respectively.

[0053] In the ASC control, when it is detected that the motor rotor angle exceeds the controllable range of the rotor angle obtained in step 120, the corresponding ASC operation is performed according to the type of short-circuited bridge arm previously diagnosed. That is, if the bridge arm with the short-circuit fault is the upper bridge arm (for example, the upper bridge arm of phase A), active short-circuit control is performed for the upper bridge arm, that is, the three-phase upper bridge arm is turned on and the three-phase lower bridge arm is turned off; if the bridge arm with the short-circuit fault is the lower bridge arm (for example, the lower bridge arm of phase B), active short-circuit control is performed for the lower bridge arm, that is, the three-phase lower bridge arm is turned on and the upper bridge arm is turned off.

[0054] When the AC motor enters the ASC state, the current path of the motor changes because a specific bridge arm of the inverter is short-circuited. This change causes the motor to generate braking torque and eventually reach the ASC steady-state current. The braking torque value and the ASC steady-state current value are mainly determined by the motor parameters (for example, the number of pole pairs, permanent magnet flux, inductance, angular velocity, and stator resistance) and the motor operating state (for example, the angular velocity of the motor), rather than being actively set by the controller. Taking a three-phase permanent magnet synchronous motor and a three-phase full-bridge inverter as an example, the steady-state quadrature-axis current i in the ASC state is q_ASC , steady-state direct-axis current i d_ASC , and the generated braking torque T em_ASC It can be calculated by the following formula:

[0055]

[0056] Among them, p n is the number of motor pole pairs, ψ m is the permanent magnet flux of the motor, L d is the direct-axis inductance, L q is the quadrature axis inductance, ω is the angular velocity of the motor, R s is the stator resistance of the motor.

[0057] Since it is impossible to control the torque generated by the motor under ASC control (i.e., the braking torque T em_ASC ) to intervene, therefore, the average torque output within one electrical cycle can be achieved to reach the desired value (for example, the driver's required torque) by intervening in the target torque under the torque output current loop control. Specifically, the target torque is determined by the proportion of the rotor angle range of the AC motor outputting the target torque to the entire electrical cycle. Target torque It can be calculated as follows:

[0058]

[0059] Among them, θ * T is the length of the rotor angle range of the AC motor output target torque; em_ASC is the braking torque output by the AC motor in the active short-circuit state; T em_avg is the expected value of the average torque, which depends on factors such as the vehicle's driving needs (e.g., accelerator pedal position, target vehicle speed and acceleration provided by the autonomous driving system), powertrain performance parameters (e.g., motor efficiency) and driving conditions (e.g., uphill environment).

[0060] When the motor rotor angle is within the rotor angle range determined in step 120, torque output current loop control is performed. The core of this control method is to use current closed-loop control and discontinuous pulse width modulation (DPWM) to control the AC motor to output the target torque. In motor vector control, in order to obtain the target torque It is necessary to control the quadrature axis component and direct axis component of the motor stator current. Usually, the quadrature axis current command value and direct axis current command value It is obtained by looking up a table, in which the optimal current command values ​​under different operating conditions are pre-stored.

[0061] It should be noted that whether the motor enters the weak magnetic field area will significantly affect the choice of control strategy. Weak magnetic field means that when the motor is running at high speed, in order to limit the inverter output voltage to not exceed its rated value, it is necessary to reduce the magnetic field (magnetic flux) of the permanent magnet to weaken the magnetic field, thereby reducing the back EMF. If weak magnetic field control is not performed, the back EMF will increase linearly with the increase in motor speed. When the back EMF exceeds the bus voltage, the motor will not be able to continue to accelerate. Therefore, it is crucial to determine whether the motor has entered the weak magnetic field area. This judgment is usually based on the target torque. If it is determined that the motor will enter the weak magnetic field area, the maximum torque voltage ratio (MTPV) control strategy is adopted. For example, the MTPV table can be searched and the corresponding relationship between the target torque and the current command value in the MTPV table can be used to determine the maximum torque voltage ratio (MTPV) control strategy. and Otherwise, the maximum torque to current ratio (MTPA) control strategy is adopted. For example, the MTPA table can be searched and the corresponding relationship between the target torque and the current command value in the MTPA table can be used to determine and The goal of both strategies is to maximize torque output, but they differ in the operating areas and constraints.

[0062] Next, based on the current closed-loop control, and Convert to quadrature axis voltage command value and direct-axis voltage command value Current closed-loop control is the core link of motor vector control. The specific process is as follows: Get the actual motor current value i q and i d , which is usually achieved by installing a current sensor on the motor stator; calculate the actual current value i q 、i d With instruction value The deviation is input into the PI controller to obtain and Due to the calculated and is the voltage command value in the dq coordinate system. In order to drive the motor, these values ​​need to be converted into pulse width modulation (PWM) signals in the three-phase abc coordinate system. This is usually achieved through space vector modulation (SVM) or discontinuous pulse width modulation (DPWM) technology. SVM and DPWM will be based on and The magnitude and direction of the voltage vector are selected, and the application time of each vector is calculated to finally generate the PWM signal for controlling the inverter. In the case of a single bridge arm short circuit fault, DPWM is usually more suitable. In addition, when the upper bridge arm is short-circuited, the zero vector can only use V 7, so the modulation uses the DPWMMAX method; when the lower bridge arm is short-circuited, the zero vector can only use V 0 , so the modulation uses the DPWMMIN method. Finally, the generated PWM signal is sent to the inverter to control the on and off of the inverter's switching devices, thereby generating the required voltage to drive the motor stator winding and ultimately achieve the output target torque.

[0063] It should be noted that in the embodiment where only the above two control modes (i.e., ASC control and torque output current loop control) exist, θ * Directly depends on the controllable range of the rotor angle determined in step 120. For example, if the controllable range of the rotor angle is [-π / 3-θ v ,π / 3-θ v ], then θ * (The length of the rotor angle range within which the AC motor outputs the target torque) is 2π / 3. This means that the motor will output the target torque within a rotor angle range of 2π / 3. The braking torque T is output within the remaining 4π / 3 rotor angle range. em_ASC . Figure 3 FIG. 4 shows a schematic waveform diagram of the motor output torque under the fault-tolerant control method according to an embodiment of the present application. Figure 3 As shown, the motor output torque is in the form of pulses. In a complete electrical cycle, the motor outputs the target torque for about 1 / 3 of the time. The remaining 2 / 3 of the time is output as braking torque T em_ASC .

[0064] In other embodiments according to the present application, a steady-state ASC current loop control is inserted between the above-mentioned two control modes to achieve the connection between the torque output current loop control and the ASC control, so as to avoid excessive current shock when switching into the ASC control. Specifically, a transition angle range can be set at the end of the controllable range of the rotor angle, and the upper boundary of the transition angle range coincides with the upper boundary of the controllable range. When the real-time motor rotor angle enters the transition angle range, the system will enter the steady-state ASC current loop control stage. Specifically, when the motor rotor angle is within the transition angle range, the current closed-loop control can be used to smoothly control the motor current to the steady-state quadrature-axis current i q_ASC and the steady-state direct-axis current i d_ASC After that, when the motor rotor angle rotates outside the transition angle range and switches to ASC control, due to the pre-performed steady-state ASC current loop control, large current shocks can be avoided, thereby ensuring the smooth operation of the motor and the stability of the system. For example, if the length of the transition angle range is Δθ ASC_Buffer , then θ * = 2π / 3 and ΔθASC_Buffer Correspondingly, the target torque The calculation formula can be further refined as:

[0065]

[0066] Reference below Figure 4 , Figure 4 is a schematic flow chart of a fault-tolerant control method 40 according to one or more embodiments of the present application.

[0067] In step 401, in response to detecting a single-arm short-circuit fault in an inverter for driving an AC motor, the fault-tolerant control method is enabled.

[0068] In step 403, the expected value of the average torque is obtained.

[0069] In step 405 , the target torque is determined according to the expected value of the average torque.

[0070] In step 407 , a current command value is determined according to the target torque, the motor speed and the bus voltage.

[0071] In step 409, the current command value is converted into a voltage command value by using current closed-loop control, and the angle θ between the stator voltage vector and the direct axis is determined. v .

[0072] In step 411, according to the short-circuit bridge arm type, angle θ v and the length of the transition angle range Δθ ASC_Buffer , determine the rotor position switching angle θ e1 ,θ e2 ,θ e3 Among them, θ e1 is the rotor angle controlled by the torque output current loop; θ e2 is the rotor angle for switching into steady-state ASC current loop control; θ e3 is the rotor angle at which ASC control is initiated. Schematically, θ e1 ,θ e2 ,θ e3 The calculation method is as follows:

[0073] θ e1 =(θ usDownlmt -θ v )

[0074] θ e2 =(θ usUplmt -θ v -Δθ ASC_Buffer )

[0075] θ e3 =(θusUplmt -θ v )

[0076] Among them, θ usDownlmt is the lower boundary of the voltage vector controllable range, θ usUplmt is the upper boundary of the voltage vector controllable range. For example, when the upper bridge arm of phase A is short-circuited, the voltage vector controllable range is [-π / 3,π / 3], and the corresponding θ usDownlmt = -π / 3, θ usUplmt is π / 3.

[0077] In step 413, according to the current motor rotor angle θ e Determine what type of control to implement.

[0078] In step 415, if θ e1 <θ e ≤θ e2 , the torque output current loop control is executed.

[0079] In step 417, if θ e2 <θ e ≤θ e3 , steady-state ASC current loop control is performed.

[0080] In step 419, if 0<θ e ≤θ e1 or θ e3 <θ e ≤2π, ASC control is performed.

[0081] Figure 5 A schematic diagram showing the relationship between time and rotor angle according to an embodiment of the present application is shown. The rotor position switching angles in the figure correspond to Figure 4 θ e1 ,θ e2 ,θ e3 .

[0082] The above-mentioned fault-tolerant control methods 10 and 40 can achieve the effect of outputting the desired average torque under the premise of not changing the hardware structure of the motor and inverter and not increasing additional costs under the premise of not changing the hardware structure of the motor and inverter and not increasing additional costs, thereby solving the problem that the vehicle cannot continue to output power and cannot achieve safe pull-over parking when a single bridge arm short circuit fault occurs. In addition, the fault-tolerant control methods 10 and 40 according to one or more embodiments of the present application add a steady-state ASC current loop control mode on the basis of the torque output current loop control and ASC control, thereby avoiding excessive current shock when switching into ASC control and ensuring the smooth operation of the motor.

[0083] Figure 66 is a schematic block diagram of an electronic device 60 according to one or more embodiments of the present application. The electronic device 60 includes a memory 610, a processor 620, and a computer program 630 stored in the memory 610 and executable on the processor 620. The execution of the computer program 630 enables the above-mentioned fault-tolerant control method 10 or 60 to be executed. Exemplarily, the electronic device 60 may be a motor control system or a controller in a motor control system, or a vehicle.

[0084] In addition, the present application can also be implemented as a computer-readable storage medium, in which a program for causing a computer to execute the above-mentioned fault-tolerant control method 10 or 40 is stored. Here, as a computer-readable storage medium, various computer-readable storage media such as disks (e.g., magnetic disks, optical disks, etc.), cards (e.g., memory cards, optical cards, etc.), semiconductor memories (e.g., ROMs, non-volatile memories, etc.), and tapes (e.g., magnetic tapes, cassette tapes, etc.) can be used.

[0085] In the applicable situation, hardware, software or a combination of hardware and software can be used to realize the various embodiments provided by the application. Moreover, in the applicable situation, without departing from the scope of the application, the various hardware components and / or software components set forth herein can be combined into a composite component comprising software, hardware and / or both. In the applicable situation, without departing from the scope of the application, the various hardware components and / or software components set forth herein can be divided into subcomponents comprising software, hardware or both. In addition, in the applicable situation, it is contemplated that the software component can be implemented as a hardware component, and vice versa.

[0086] Software according to the present application (such as program code and / or data) can be stored on one or more computer-readable storage media. It is also contemplated that the software identified herein can be implemented using one or more general or special-purpose computers and / or computer systems, networked and / or otherwise. Where applicable, the order of the various steps described herein can be changed, combined into composite steps, and / or divided into sub-steps to provide the features described herein.

[0087] The embodiments and examples set forth herein are provided to best illustrate embodiments according to the present application and its specific applications, and thereby enable those skilled in the art to implement and use the present application. However, those skilled in the art will appreciate that the above description and examples are provided only for ease of illustration and example. The description set forth is not intended to cover all aspects of the present application or to limit the present application to the precise form disclosed.

Claims

1. A fault-tolerant control method, characterized in that: The method comprises the following steps: In response to detecting a single bridge arm short circuit fault of an inverter for driving an AC motor, determining a controllable range of a voltage vector that can be used to control a stator voltage of the motor according to the type of the short-circuited bridge arm; Converting the voltage vector controllable range into a corresponding rotor angle controllable range; When the motor rotor angle is outside the controllable rotor angle range, controlling the AC motor to enter an active short-circuit state; and When the motor rotor angle is within the controllable range of the rotor angle, current closed-loop control and discontinuous pulse width modulation are used to control the AC motor to output a target torque, so that the average torque output by the AC motor in one electrical cycle reaches a desired value.

2. The fault-tolerant control method according to claim 1, characterized in that: The controllable range of the voltage vector that can be used to control the motor stator voltage is determined by the type of short-circuit bridge arm: If the upper bridge arm of phase A is short-circuited, the controllable range of the voltage vector is determined to be [-π / 3,π / 3]; If the lower bridge arm of phase A is short-circuited, the controllable range of the voltage vector is determined to be [2π / 3, 4π / 3]; If the upper bridge arm of phase B is short-circuited, the controllable range of the voltage vector is determined to be [π / 3,π]; If the lower bridge arm of phase B is short-circuited, the controllable range of the voltage vector is determined to be [4π / 3, 2π]; If the upper bridge arm of phase C is short-circuited, the controllable range of the voltage vector is determined to be [π, 5π / 3]; If the lower bridge arm of phase C is short-circuited, the controllable range of the voltage vector is determined to be [0, 2π / 3].

3. The fault-tolerant control method according to claim 1, characterized in that: The method further comprises: Based on the motor parameters and the motor operating state, the steady-state quadrature-axis current i of the AC motor in the active short-circuit state is determined. q_ASC and the steady-state direct-axis current i d_ASC ;as well as According to the torque formula, the braking torque T output by the AC motor in the active short-circuit state is determined. em_ASC .

4. The fault-tolerant control method according to claim 3, characterized in that: The method further comprises: Setting a transition angle range at the end of the controllable range of the rotor angle; and When the motor rotor angle is within the transition angle range, the motor current is controlled to the steady-state quadrature-axis current i by current closed-loop control. q_ASC and the steady-state direct-axis current i d_ASC .

5. The fault-tolerant control method according to claim 3 or 4, characterized in that: The method further comprises: The target torque is determined according to the ratio of the rotor angle range within which the AC motor outputs the target torque to the entire electrical cycle.

6. The fault-tolerant control method according to claim 5, characterized in that: The target torque is determined as follows Among them, θ * is the length of the rotor angle range within which the AC motor outputs the target torque, T em_ASC is the braking torque output by the AC motor in the active short-circuit state, T em_avg is the expected value of the average torque.

7. The fault-tolerant control method according to claim 1, characterized in that: The method further comprises: Determine the quadrature axis current command value according to the target torque, motor speed and bus voltage and direct axis current command value Using current closed loop control and Convert to quadrature axis voltage command value and direct-axis voltage command value 8. The fault-tolerant control method according to claim 7, characterized in that: Using current closed-loop control and discontinuous pulse width modulation to control the AC motor to output a target torque includes: By using discontinuous pulse width modulation, the quadrature axis voltage command value and the direct-axis voltage command value converting to a pulse width modulated signal; and The pulse width modulation signal is sent to the inverter to drive the AC motor to output the target torque.

9. The fault-tolerant control method according to claim 7, characterized in that: Converting the voltage vector controllable range into a corresponding rotor angle controllable range includes: Determine the angle θ between the stator voltage vector and the direct axis v ,in as well as The rotor angle controllable range is determined as the voltage vector controllable range and the included angle θ v The difference between .

10. The fault-tolerant control method according to claim 7, characterized in that: Determine the quadrature axis current command value according to the target torque, motor speed and bus voltage and direct axis current command value include: Determining whether the AC motor will enter a weak magnetic field region according to the target torque, motor speed and bus voltage; In response to determining that the weak magnetic field region will be entered, the maximum torque voltage ratio control strategy is used to determine and In response to determining that the current will not enter the field weakening region, the maximum torque current ratio control strategy is used to determine and

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