Motor control method and device, vehicle and storage medium

Abstract

The invention provides a motor control method and device, a vehicle and a storage medium, and the method is applied to the field of vehicles, and comprises the steps: obtaining first to third phase current values of a motor when the motor is in a locked-rotor state, and determining a zero vector adjustment value of the motor according to the first to third phase current values based on a pre-constructed zero vector adjustment distribution table, and adding the zero vector adjustment value to the current three-phase duty ratio to obtain a final three-phase duty ratio of the motor, and then determining a control signal of each phase of bridge arm of the motor based on the final three-phase duty ratio so as to control the motor according to the control signal of each phase of bridge arm. The method can dynamically change the current distribution of each phase of bridge arm of the motor, optimize the loss distribution of a power device, improve the torque output of the system and further improve the locked-rotor capability of the motor by dynamically adjusting the zero vector distribution strategy.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vehicles, and more particularly, to a control method and device of an electric machine, a vehicle and a storage medium. BACKGROUND

[0002] In the working process of a new energy vehicle electric machine, if the vehicle is continuously climbing at low speed or is in a situation of getting unstuck, it is easy to cause the electric machine to be blocked. After the electric machine is blocked, the magnetic field position of the electric machine does not change, the three-phase current changes from alternating current to direct current, and the power device (IGBT (Insulated Gate Bipolar Transistor) and diode) continuously runs at a large current on a specific bridge arm, which affects the overall performance and reliability of the system.

[0003] In related technologies, when the electric machine is blocked, the loss balance of the IGBT and the diode cannot be achieved in the electric machine blocking condition, which may cause local overheating of the specific bridge arm, and the system is forced to run at a reduced capacity, which not only affects the system torque output, but also shortens the service life of the device, and needs to be solved urgently. SUMMARY

[0004] The present application provides a control method and device of an electric machine, a vehicle and a storage medium. The method can dynamically adjust the zero vector distribution strategy, dynamically change the current distribution of each phase bridge arm of the electric machine, optimize the power device loss distribution, improve the system torque output, and further improve the blocking capability of the electric machine.

[0005] In a first aspect, a control method of an electric machine is provided. The method includes: determining whether the electric machine is in a blocked state; if the electric machine is in the blocked state, obtaining first to third phase current values of the electric machine, and determining a zero vector adjustment value of the electric machine according to the first to third phase current values based on a pre-constructed zero vector adjustment distribution table; obtaining current three-phase duty cycles of the electric machine, adding the zero vector adjustment value to the current three-phase duty cycles respectively to obtain final three-phase duty cycles of the electric machine, and determining control signals of each phase bridge arm of the electric machine based on the final three-phase duty cycles, so as to control the electric machine according to the control signals of each phase bridge arm. Through the above technical solution, the zero vector distribution strategy can be dynamically adjusted, the current distribution of each phase bridge arm of the electric machine can be dynamically changed, the power device loss distribution can be optimized, the system torque output can be improved, and the blocking capability of the electric machine can be further improved.

[0006] In some possible implementation manners, in combination with the first aspect, the determining whether the motor is in the locked-rotor state comprises: obtaining a current torque value of the motor and a current rotating speed value of the motor; determining whether the current torque value of the motor is greater than a preset torque threshold and whether the current rotating speed value of the motor is less than a preset rotating speed threshold; and if the current torque value is greater than the preset torque threshold and the current rotating speed value is less than the preset rotating speed threshold, determining that the motor is in the locked-rotor state.

[0007] By the foregoing technical solution, compensation is ensured to be performed only when the motor is in the locked-rotor state, so that the application boundary can be accurately delimited, strategy abuse can be prevented, and overall control efficiency can be improved.

[0008] In some possible implementation manners, in combination with the first aspect and the foregoing implementation manners, the determining, based on the pre-constructed zero-vector adjustment distribution table, of the zero-vector adjustment value of the motor according to the first to third phase current values comprises: determining a current direction corresponding to a current value with the largest absolute value among the first to third phase current values; calculating a first difference value of two current values with larger absolute values among the first to third phase current values; and matching the zero-vector adjustment value from the pre-constructed zero-vector adjustment distribution table according to the current direction and the first difference value.

[0009] By the foregoing technical solution, the degree of current asymmetry is directly quantified based on the calculation of the first difference value of the maximum current value and the intermediate current value, thereby providing a main basis for the demand of the compensation amount.

[0010] In some possible implementation manners, in combination with the first aspect and the foregoing implementation manners, the determining of the current direction corresponding to the current value with the largest absolute value among the first to third phase current values comprises: identifying the current value with the largest absolute value among the first to third phase current values; and obtaining an original current sign of the current value, and determining the current direction according to the original current sign.

[0011] By the foregoing technical solution, the distribution mode of thermal stress under the current working condition is accurately identified based on the determination of the current direction, which is a key criterion for determining the compensation direction (whether to increase the upper-bridge zero vector or the lower-bridge zero vector) and the specific value.

[0012] In some possible implementation manners, in combination with the first aspect and the foregoing implementation manners, before the zero vector adjustment value of the motor is determined according to the first to third phase current values based on the pre-constructed zero vector adjustment distribution table, the method further includes: controlling the motor to stall to a plurality of groups of target stall angles respectively, and applying a target torque when the motor is at each group of target stall angles; obtaining three-phase currents and three-phase duty cycles under any group of target stall angles and target torque, and monitoring a temperature difference value of target power devices between upper and lower bridge arms corresponding to a current with the largest absolute value in the three-phase currents under the any group of target stall angles and target torque; dynamically adjusting the three-phase duty cycles under the corresponding group of target stall angles and target torque based on the temperature difference value under the any group of target stall angles and target torque, until a new temperature difference value meets a preset standard, and obtaining the zero vector adjustment value under the corresponding group of target stall angles and target torque according to an adjustment result; and establishing a mapping relationship between the three-phase currents and the three-phase duty cycles under each group of target stall angles and target torque and the zero vector adjustment value under the corresponding group of target stall angles and target torque, and constructing the zero vector adjustment distribution table according to the mapping relationship.

[0013] By the foregoing technical solution, by testing a plurality of stall angles and torques of the motor, all key stall working conditions can be covered, and a control blind area can be eliminated, so that the controller can always find compensation parameters closest to a current working condition in the zero vector adjustment distribution table when the vehicle stalls in any road condition.

[0014] In some possible implementation manners, in combination with the first aspect and the foregoing implementation manners, after it is determined whether the motor is in a stall state, the method further includes: if the motor is not in the stall state, directly determining a control signal of each phase bridge arm of the motor according to a current three-phase duty cycle of the motor, and controlling the motor according to the control signal of each phase bridge arm of the motor.

[0015] By the foregoing technical solution, when the motor is not in the stall working condition, a control signal of each phase bridge arm of the motor is directly determined according to a current three-phase duty cycle, so that heat generated by upper and lower bridge arms is evenly distributed, overheating of a certain phase bridge arm in the stall process is avoided, and the stall capability of the controller is improved.

[0016] In some possible implementation manners, in combination with the first aspect and the foregoing implementation manners, the method for controlling the motor further includes: determining whether a current driving working condition of the vehicle meets a self-learning condition; if the current driving working condition meets the self-learning condition, applying a target disturbance amount on the basis of the zero vector adjustment value; monitoring a temperature difference value change direction of the target power devices after the target disturbance amount is applied, to determine an update strategy of the zero vector adjustment value based on the temperature difference value change direction; and updating the zero vector adjustment distribution table based on the updated zero vector adjustment value.

[0017] By the technical solution, a self-learning strategy is introduced into the zero vector adjustment allocation table, so that the zero vector adjustment allocation table can be updated based on self-learning to ensure the accuracy of motor control.

[0018] In a second aspect, a control device of a motor is provided, which comprises: A judgment module is configured to judge whether the motor is in a locked-rotor state. A determination module is configured to, if the motor is in the locked-rotor state, acquire first to third phase current values of the motor, and determine a zero vector adjustment value of the motor according to the first to third phase current values based on a pre-constructed zero vector adjustment allocation table. A control module is configured to acquire current three-phase duty cycles of the motor, add the zero vector adjustment value to the current three-phase duty cycles respectively to obtain final three-phase duty cycles of the motor, and determine a control signal of each phase bridge arm of the motor based on the final three-phase duty cycles, so as to control the motor according to the control signal of each phase bridge arm.

[0019] In combination with the second aspect, in some possible implementation manners, the judgment module comprises: A first acquisition unit is configured to acquire a current torque value of the motor and a current rotating speed value of the motor. A first judgment unit is configured to judge whether the current torque value of the motor is greater than a preset torque threshold and whether the current rotating speed value of the motor is less than a preset rotating speed threshold. A determination unit is configured to, if the current torque value is greater than the preset torque threshold and the current rotating speed value is less than the preset rotating speed threshold, determine that the motor is in the locked-rotor state.

[0020] In combination with the second aspect and the above implementation manners, in some possible implementation manners, the determination module comprises: A determination unit is configured to determine a current direction corresponding to a current value with the largest absolute value among the first to third phase current values. A calculation unit is configured to calculate a first difference value of two current values with larger absolute values among the first to third phase current values. A matching unit is configured to match the zero vector adjustment value from the pre-constructed zero vector adjustment allocation table according to the current direction and the first difference value.

[0021] In combination with the second aspect and the above implementation manners, in some possible implementation manners, the determination unit comprises: An identification sub-unit is configured to identify the current value with the largest absolute value among the first to third phase current values. The acquisition subunit is configured to acquire an original current sign of the current value and determine the current direction according to the original current sign.

[0022] With reference to the second aspect and the foregoing implementations, in some possible implementations, the determination module comprises: The first control unit is configured to control the motor to stall to a plurality of groups of target stall angles respectively, and apply target torques when the motor is at each group of target stall angles respectively. The second acquisition unit is configured to acquire three-phase currents and three-phase duty cycles under any group of target stall angles and target torques, and monitor a temperature difference value of target power devices between upper and lower bridges of a target bridge arm corresponding to a current with the largest absolute value in the three-phase currents under the any group of target stall angles and target torques. The first adjustment unit is configured to dynamically adjust the three-phase duty cycles under the corresponding group of target stall angles and target torques based on the temperature difference value under the any group of target stall angles and target torques, until a new temperature difference value meets a preset standard, and obtain a zero-vector adjustment value under the corresponding group of target stall angles and target torques according to an adjustment result. The construction unit is configured to establish a mapping relationship between the three-phase currents and the three-phase duty cycles under each group of target stall angles and target torques and the zero-vector adjustment value under the corresponding group of target stall angles and target torques, and construct the zero-vector adjustment distribution table according to the mapping relationship.

[0023] With reference to the second aspect and the foregoing implementations, in some possible implementations, after determining whether the motor is in the stall state, the determination module further comprises: The second control unit is configured to, if the motor is not in the stall state, directly determine control signals of each phase bridge arm of the motor according to current three-phase duty cycles of the motor, and control the motor according to the control signals of each phase bridge arm of the motor.

[0024] With reference to the second aspect and the foregoing implementations, in some possible implementations, the control apparatus of the motor further comprises: The second determination unit is configured to determine whether a current driving condition of the vehicle meets a self-learning condition. The second adjustment unit is configured to, if the current driving condition meets the self-learning condition, apply a target disturbance quantity on the basis of the zero-vector adjustment value. The monitoring unit is configured to monitor a temperature difference value change direction of the target power devices after the target disturbance quantity is applied, to determine an update strategy of the zero-vector adjustment value based on the temperature difference value change direction. The update unit is configured to update the zero-vector adjustment distribution table based on the updated zero-vector adjustment value.

[0025] In a third aspect, a vehicle is provided, comprising the motor control method described in the above embodiments.

[0026] In a fourth aspect, a computer program product is provided, which comprises computer program code, which, when executed on a computer, causes the computer to perform the method in the first aspect or any possible implementation manner of the first aspect.

[0027] In a fifth aspect, a computer-readable storage medium is provided, which stores computer program code, which, when executed on a computer, causes the computer to perform the method in the first aspect or any possible implementation manner of the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A hardware topology diagram of a motor controller of the related art; Figure 2 A flowchart of the motor control method provided by an embodiment of the present application; Figure 3 A system architecture diagram of an embodiment of the present application; Figure 4 A zero vector dynamic allocation logic flowchart of an embodiment of the present application; Figure 5 A power device temperature change diagram before improvement of an embodiment of the present application; Figure 6 A power device temperature change diagram after improvement of an embodiment of the present application; Figure 7 A block diagram of the motor control device provided by an embodiment of the present application; Figure 8 A structure diagram of the vehicle of an embodiment of the present application. DETAILED DESCRIPTION

[0029] The technical solutions in the present application will be described in detail below with reference to the drawings. In the description of the embodiments of the present application, unless otherwise specified, " / " represents the meaning of or, for example, A / B can represent A or B: "and / or" in the text is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist together, and B exists alone, and in addition, in the description of the embodiments of the present application, "multiple" means two or more than two.

[0030] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0031] In the application scenarios of new energy vehicles, such as Figure 1 As shown, motors often face operating conditions such as low-speed climbing or getting out of trouble. Under these conditions, the motor is prone to stalling. After the motor stalls, the position of the motor magnetic field remains unchanged, and the three-phase current changes from AC to DC. This causes the power devices (such as IGBTs and diodes) on certain bridge arms to operate at high current continuously, resulting in local overheating, affecting the system torque output, and shortening the device life. Therefore, based on the above-mentioned problems, a method is needed to improve the motor stall capability, optimize the loss distribution of power devices on specific bridge arms, improve the system torque output, and extend the device life.

[0032] Figure 2 This is a schematic flowchart of a vehicle control method provided in an embodiment of this application.

[0033] For example, such as Figure 2 As shown, the method includes: In step S201, it is determined whether the motor is in a stalled state.

[0034] Optionally, in one embodiment of this application, determining whether the motor is in a stalled state includes: obtaining the current torque value and the current speed value of the motor; determining whether the current torque value of the motor is greater than a preset torque threshold and whether the current speed value of the motor is less than a preset speed threshold; if the current torque value is greater than the preset torque threshold and the current speed value is less than the preset speed threshold, then the motor is determined to be in a stalled state.

[0035] The preset torque threshold and preset speed threshold can be set by those skilled in the art according to actual testing needs, or they can be obtained through a limited number of computer simulations, or they can be values ​​calibrated by the motor parameters. No specific limitations are made here.

[0036] Specifically, to address the issue of localized overheating of power devices on specific bridge arms caused by motor stalling during low-speed climbing or getting out of trouble, which affects the power device losses on those bridge arms and the overall system performance, this application embodiment dynamically adjusts the zero-vector allocation strategy to dynamically change the current distribution of each phase bridge arm of the motor, optimize the power device loss distribution, improve the system torque output, and thus enhance the motor stall capability.

[0037] Specifically, such as Figure 3As shown, the system architecture related to the embodiments of the present application mainly includes four parts, which are a signal acquisition module, a signal processing module, a zero vector dynamic allocation module, and a PWM (Pulse Width Modulation) generation module. The signal acquisition module is used to acquire the current value of the motor, the first to third phase current values Iu, Iv, Iw of the motor, the current torque value of the motor, and the current speed value of the motor. The signal processing module is used to process and calculate the first to third phase current values acquired above, calculate the maximum current after taking the absolute value and the current difference DeltCurrent and its direction after taking the absolute value, and determine whether the motor is in a locked-rotor state. The zero vector dynamic allocation module is used to query the pre-constructed zero vector adjustment allocation table according to the current difference DeltCurrent and the maximum current direction, and output the corresponding zero vector adjustment value DeltDuty to dynamically adjust the three-phase duty ratio of the motor, i.e., the three-phase PWM signals DutyU, DutyV, and DutyW. The PWM generation module is used to send the adjusted three-phase PWM signals to the motor controller to control the switching of the power unit to drive the motor to output the corresponding torque.

[0038] As shown, in the process of determining whether the motor is in a locked-rotor state, first, it is necessary to determine whether the current torque value of the motor is greater than a preset torque threshold T (for example, greater than 80% of the rated torque) and whether the current speed value of the motor is less than a preset speed threshold n (for example, less than 50 rpm). If the current torque value is greater than the preset torque threshold T and the current speed value is less than the preset speed threshold n, it is determined that the motor is in a locked-rotor state. Figure 4 In step S202, if the motor is in a locked-rotor state, the first to third phase current values of the motor are acquired, and the zero vector adjustment value of the motor is determined according to the first to third phase current values based on the pre-constructed zero vector adjustment allocation table.

[0039] Optionally, in an embodiment of the present application, determining the zero vector adjustment value of the motor according to the first to third phase current values based on the pre-constructed zero vector adjustment allocation table includes: determining the current direction corresponding to the current value with the largest absolute value among the first to third phase current values; calculating a first difference value of the two current values with larger absolute values among the first to third phase current values; and matching the zero vector adjustment value from the pre-constructed zero vector adjustment allocation table according to the current direction and the first difference value.

[0040] Optionally, in an embodiment of the present application, determining the current direction corresponding to the current value with the largest absolute value among the first to third phase current values includes: identifying the current value with the largest absolute value among the first to third phase current values; and acquiring the original current sign of the current value and determining the current direction according to the original current sign.

[0041] ​

[0042] Specifically, if the motor is in the locked-rotor state, first, based on the collected first to third phase current values, the absolute values of the first to third phase current values are taken respectively, and the current direction (positive or negative) corresponding to the current value with the largest absolute value in the first to third phase current values is determined, and the first difference value of the two current values with larger absolute values in the first to third phase current values is calculated, that is, in the calculation of the first to third phase current values, the first difference value DeltCurrent of the maximum current value after taking the absolute value and the intermediate current value is calculated, for example, ABS(Ia)>ABS(Ib)>ABS(Ib), then DeltCurrent=ABS(Ia)-ABS(Ib); then, according to the current direction corresponding to the maximum current value and the first difference value DeltCurrent of the maximum current value and the intermediate current value, the corresponding zero vector adjustment value DeltDuty is matched from the pre-constructed zero vector adjustment distribution table, so as to adjust the three-phase duty ratio of the motor through the zero vector adjustment value DeltDuty.

[0043] Among them, the embodiment of the application can identify the current value with the largest absolute value in the first to third phase current values, and obtain the original current symbol of the current value with the largest absolute value, so as to determine the current direction according to the original current symbol.

[0044] Therefore, based on the calculation of the first difference value of the maximum current value and the intermediate current value, the degree of current asymmetry is directly quantified, thereby providing the main basis for the demand of compensation amount, and based on the determination of the current direction, the distribution mode of the thermal stress under the current working condition is also accurately identified, which is the key criterion for determining the compensation direction (whether to increase the upper bridge zero vector or the lower bridge zero vector) and the specific value.

[0045] Optionally, in an embodiment of the application, before determining the zero vector adjustment value of the motor according to the first to third phase current values based on the pre-constructed zero vector adjustment distribution table, it further comprises: controlling the motor to be locked to a plurality of groups of target locked-rotor angles respectively, and applying a target torque when the motor is at each group of target locked-rotor angles; obtaining the three-phase current and three-phase duty ratio under any group of target locked-rotor angles and target torque, and monitoring the temperature difference value of the target power device between the upper and lower bridges corresponding to the current with the largest absolute value in the three-phase current under any group of target locked-rotor angles and target torque; based on the temperature difference value under any group of target locked-rotor angles and target torque, dynamically adjusting the three-phase duty ratio under the corresponding group of target locked-rotor angles and target torque until the new temperature difference value meets the preset standard, and obtaining the zero vector adjustment value under the corresponding group of target locked-rotor angles and target torque according to the adjustment result; establishing a mapping relationship between the three-phase current and three-phase duty ratio under each group of target locked-rotor angles and target torque and the zero vector adjustment value under the corresponding group of target locked-rotor angles and target torque, and constructing the zero vector adjustment distribution table according to the mapping relationship.

[0046] Specifically, before determining the zero vector adjustment value of the motor according to the first to third phase current values based on the pre-constructed zero vector adjustment distribution table, the application embodiment needs to further explain the construction of the zero vector adjustment distribution table.

[0047] Specifically, the motor of the application embodiment is tested in a bench environment. First, the locked-rotor angle and torque of the motor are tested in multiple groups to determine the compensation value under each group of locked-rotor angle and torque, that is, the motor is controlled to lock-rotate to multiple target locked-rotor angles, respectively, and a target torque is applied when the motor is at each target locked-rotor angle, so that the three-phase current and three-phase duty cycle under any target locked-rotor angle and target torque can be obtained. The three-phase duty cycle is the original three-phase duty cycle DutyU, DutyV, DutyW of the motor. At this time, the temperature difference between the upper and lower bridge power devices of the bridge arm corresponding to the maximum current of the motor controller will occur, so it is necessary to monitor the temperature difference of the target power device between the upper and lower bridges of the target bridge arm corresponding to the current with the largest absolute value in the three-phase current under any target locked-rotor angle and target torque.

[0048] Secondly, a certain compensation value is added or reduced to the original three-phase duty cycle DutyU, DutyV, DutyW to dynamically adjust the three-phase duty cycle under the corresponding target locked-rotor angle and target torque until the new temperature difference meets the preset standard. The preset standard can be understood as ensuring that the temperature of the bridge power device of the bridge arm corresponding to the maximum current is balanced. Thus, the zero vector adjustment value under the corresponding target locked-rotor angle and target torque can be obtained according to the adjustment result, that is, the compensation value is the zero vector adjustment value Deltduty under the temperature difference and the direction of the maximum current. As shown in Table 1: Table 1

[0049] Finally, a mapping relationship between the three-phase current and three-phase duty cycle under each target locked-rotor angle and target torque and the zero vector adjustment value under the corresponding target locked-rotor angle and target torque is established, and a zero vector adjustment distribution table is constructed according to the mapping relationship.

[0050] Thus, by testing multiple locked-rotor angles and torques of the motor, all key locked-rotor working conditions can be covered, and the control blind area can be eliminated, so that the controller can always find the closest compensation parameter in the zero vector adjustment distribution table under the current working condition when the vehicle is locked-rotated under any road condition (such as the tire being stuck in a specific position).

[0051] In step S203, the current three-phase duty cycles of the motor are obtained, the zero vector adjustment values are added to the current three-phase duty cycles respectively, the final three-phase duty cycles of the motor are obtained, and the control signals of each phase bridge arm of the motor are determined based on the final three-phase duty cycles to control the motor according to the control signals of each phase bridge arm.

[0052] Specifically, after the current direction corresponding to the current value with the largest absolute value among the first to third phase current values of the motor and the first difference of the two current values with larger absolute values among the first to third phase current values are obtained, the zero vector adjustment distribution table is further searched, and the corresponding zero vector adjustment value DeltDuty is output, and the zero vector adjustment value DeltDuty is added to the current three-phase duty cycles DutyU, DutyV and DutyW respectively, i.e. DutyU+DeltDuty, DutyV+DeltDuty and DutyW+DeltDuty, and then the adjusted final three-phase duty cycles FinalOutputDutyU, FinalOutputDutyV and FinalOutputDutyW are obtained, that is, FinalOutputDutyU=DutyU+DeltDuty, FinalOutputDutyV=DutyV+DeltDuty and FinalOutputDutyW=DutyW+DeltDuty. Finally, the adjusted final three-phase duty cycles are sent to the PWM generator of the motor controller, and the actual switching signals are generated by the PWM generator of the motor controller to determine the control signals of each phase bridge arm of the motor to control the motor according to the control signals of each phase bridge arm, and output the motor torque, as shown in Figure 5 and Figure 6 As shown, the temperatures of the IGBT and the diode are obviously balanced after adjustment, and the temperature of the diode is also obviously reduced, and the output torque is significantly improved under the same maximum temperature of the power device.

[0053] Optionally, in an embodiment of the present application, after it is judged whether the motor is in the stall state, the method further comprises: if the motor is not in the stall state, directly determining the control signals of each phase bridge arm of the motor according to the current three-phase duty cycles of the motor, and controlling the motor according to the control signals of each phase bridge arm of the motor.

[0054] Specifically, as shown in Figure 4As shown, if the motor is not in the locked-rotor state, the current three-phase duty cycle of the motor does not need to be adjusted at this time, and thus the control signal of each phase bridge arm of the motor can be directly determined according to the current three-phase duty cycle of the motor. At this time, FinalOutputDutyU=DutyU, FinalOutputDutyV=DutyV, and FinalOutputDutyW=DutyW, and the current three-phase duty cycle is sent to the PWM generator of the motor controller. At this time, the PWM generator of the motor controller generates the actual switching signal, determines the control signal of each phase bridge arm of the motor, controls the motor according to the control signal of each phase bridge arm, and then outputs the motor torque.

[0055] Therefore, when the motor is not in the locked-rotor state, the control signal of each phase bridge arm of the motor can be directly determined according to the current three-phase duty cycle, so that unnecessary energy loss can be avoided, the heat generated by the upper and lower bridge arms is evenly distributed, overheating of a phase bridge arm during the locked-rotor process is avoided, and the locked-rotor capability of the controller is improved.

[0056] Optionally, in an embodiment of the present application, the method further includes: determining whether the current driving condition of the vehicle meets a self-learning condition; if the current driving condition meets the self-learning condition, applying a target disturbance amount on the basis of the zero-vector adjustment value; monitoring the temperature difference change direction of the target power device after the target disturbance amount is applied, to determine an update strategy of the zero-vector adjustment value on the basis of the temperature difference change direction; and updating the zero-vector adjustment distribution table on the basis of the updated zero-vector adjustment value.

[0057] Specifically, to avoid deviations caused by device aging, temperature drift, and batch differences, the embodiment of the present application can introduce a self-learning strategy to the zero-vector adjustment distribution table, so that the zero-vector adjustment distribution table can be updated on the basis of self-learning, to ensure the accuracy of motor control.

[0058] Specifically, when the vehicle is in a low-risk, torque disturbance-insensitive (for example, the vehicle is stationary, low-speed creeping, coasting, etc.) condition, it can be determined that the current driving condition meets the self-learning condition, and a target disturbance amount, which is a small known disturbance, is applied as an excitation signal on the basis of the zero-vector adjustment value. Then, the temperature difference change direction of the upper and lower bridge target power devices of the bridge arm before the target disturbance amount is increased is further observed, to determine the adjustment direction of the zero-vector adjustment value DeltDuty on the basis of the temperature difference change direction. At this time, a new zero-vector adjustment value DeltDuty is obtained, and the zero-vector adjustment distribution table is updated according to the new zero-vector adjustment value DeltDuty, to achieve adaptive loss balancing control and ensure long-term reliability.

[0059] Therefore, based on the specific discussion of the above embodiment, the following beneficial effects can be achieved: (1) By dynamically adjusting the distribution ratio of zero vector adjustment value in upper and lower bridge arms, the loss distribution of inverter power devices (IGBT and diode) is actively balanced, which can improve the sustained output capability of the motor in the locked-rotor condition; (2) By accurate zero vector adjustment value compensation, the local overheating problem of power devices can be effectively solved, and the system reliability and service life are improved; (3) The complex online optimization problem is converted into a "pre-calibration, real-time table lookup" mode. According to the current direction of the maximum phase and the intermediate phase current difference and absolute value, the optimal zero vector adjustment value can be directly obtained from the pre-stored zero vector adjustment distribution table, and the real-time performance of motor control is improved.

[0060] In summary, according to the motor control method of the embodiment of the application, when the motor is in the locked-rotor state, the first to third phase current values of the motor are obtained, and based on the pre-constructed zero vector adjustment distribution table, the zero vector adjustment value of the motor is determined according to the first to third phase current values, and the zero vector adjustment value is added to the current three-phase duty cycle to obtain the final three-phase duty cycle of the motor. Then, based on the final three-phase duty cycle, the control signal of each phase bridge arm of the motor is determined to control the motor according to the control signal of each phase bridge arm. This method can dynamically adjust the zero vector distribution strategy, thereby dynamically changing the current distribution of each phase bridge arm of the motor, optimizing the power device loss distribution, improving the system torque output, and further improving the locked-rotor capability of the motor.

[0061] Figure 7 is a structural schematic diagram of a motor control device provided by the embodiment of the application.

[0062] For example, as shown in Figure 7 The device can include a judgment module 100, a determination module 200, and a control module 300.

[0063] The judgment module 100 is configured to determine whether the motor is in a locked-rotor state. The determination module 200 is configured to, if the motor is in the locked-rotor state, obtain first to third phase current values of the motor, and determine a zero vector adjustment value of the motor based on a pre-constructed zero vector adjustment distribution table according to the first to third phase current values. The control module 300 is configured to obtain current three-phase duty cycles of the motor, add the zero vector adjustment value to the current three-phase duty cycles to obtain final three-phase duty cycles of the motor, and determine control signals of each phase bridge arm of the motor based on the final three-phase duty cycles, so as to control the motor according to the control signals of each phase bridge arm.

[0064] Optionally, in an embodiment of the application, the judgment module 100 includes: The first acquisition unit is configured to acquire a current torque value of the motor and a current rotating speed value of the motor. The first judgment unit is configured to judge whether the current torque value of the motor is greater than a preset torque threshold and whether the current rotating speed value of the motor is less than a preset rotating speed threshold. The determination unit is configured to determine that the motor is in a locked-rotor state if the current torque value is greater than the preset torque threshold and the current rotating speed value is less than the preset rotating speed threshold.

[0065] Optionally, in an embodiment of the present application, the determination module 200 comprises: The determination unit is configured to determine a current direction corresponding to a current value with the largest absolute value among the first to third phase current values. The calculation unit is configured to calculate a first difference value of two current values with larger absolute values among the first to third phase current values. The matching unit is configured to match a zero vector adjustment value from a pre-constructed zero vector adjustment distribution table according to the current direction and the first difference value.

[0066] Optionally, in an embodiment of the present application, the determination unit comprises: The identification subunit is configured to identify a current value with the largest absolute value among the first to third phase current values. The acquisition subunit is configured to acquire an original current sign of the current value and determine the current direction according to the original current sign.

[0067] Optionally, in an embodiment of the present application, the determination module 200 comprises: The first control unit is configured to control the motor to be locked to a plurality of groups of target locked-rotor angles respectively, and to apply a target torque when the motor is at each group of target locked-rotor angles. The second acquisition unit is configured to acquire three-phase currents and three-phase duty cycles under any group of target locked-rotor angles and target torques, and to monitor a temperature difference value of target power devices between upper and lower bridges of a target bridge arm corresponding to a current with the largest absolute value among the three-phase currents under any group of target locked-rotor angles and target torques. The first adjustment unit is configured to dynamically adjust the three-phase duty cycles under the corresponding group of target locked-rotor angles and target torques based on the temperature difference value under any group of target locked-rotor angles and target torques until a new temperature difference value meets a preset standard, and to obtain a zero vector adjustment value under the corresponding group of target locked-rotor angles and target torques according to the adjustment result. The construction unit is configured to establish a mapping relationship between the three-phase currents and the three-phase duty cycles under each group of target locked-rotor angles and target torques and the zero vector adjustment value under the corresponding group of target locked-rotor angles and target torques, and to construct a zero vector adjustment distribution table according to the mapping relationship.

[0068] Optionally, in an embodiment of the present application, after judging whether the motor is in the locked-rotor state, the judging module 100 further comprises: The second control unit is configured to, if the motor is not in the locked-rotor state, directly determine the control signal of each phase bridge arm of the motor according to the current three-phase duty cycle of the motor, and control the motor according to the control signal of each phase bridge arm of the motor.

[0069] Optionally, in an embodiment of the present application, the motor control device 10 described above further comprises: The second judging unit is configured to judge whether the current driving condition of the vehicle meets the self-learning condition. The second adjusting unit is configured to, if the current driving condition meets the self-learning condition, apply a target disturbance amount on the basis of the zero-vector adjustment value. The monitoring unit is configured to monitor the temperature difference value change direction of the target power device after the target disturbance amount is applied, so as to determine the update strategy of the zero-vector adjustment value on the basis of the temperature difference value change direction. The updating unit is configured to update the zero-vector adjustment distribution table on the basis of the updated zero-vector adjustment value.

[0070] In summary, according to the motor control device of the embodiment of the present application, when the motor is in the locked-rotor state, the first to third phase current values of the motor are obtained, and the zero-vector adjustment value of the motor is determined on the basis of the first to third phase current values and the zero-vector adjustment distribution table constructed in advance, and the zero-vector adjustment value is added to the current three-phase duty cycle respectively to obtain the final three-phase duty cycle of the motor, and then the control signal of each phase bridge arm of the motor is determined on the basis of the final three-phase duty cycle, so as to control the motor according to the control signal of each phase bridge arm. This method can dynamically adjust the zero-vector distribution strategy, thereby dynamically changing the current distribution of each phase bridge arm of the motor, optimizing the power device loss distribution, improving the system torque output, and further improving the locked-rotor capability of the motor.

[0071] Figure 8 The embodiment of the present application provides a structural schematic diagram of a vehicle.

[0072] It should be understood that the method described above can be applied to Figure 8 the vehicle shown in the structure.

[0073] In addition, the embodiment of the present application also protects a device, which can include a memory and a processor, wherein the memory stores executable program codes, and the processor is configured to call and execute the executable program codes to execute the motor control method provided by the embodiment of the present application.

[0074] Further, the device further comprises a communication interface 803 for communication between the memory 801 and the processor 802.

[0075] The embodiment can divide the functions of the device according to the method examples described above, for example, each function module can be obtained, or two or more functions can be integrated into a processing module. The integrated module can be realized in the form of hardware. It should be noted that the division of the modules in the embodiment is illustrative, and is only a logical function division. In actual implementation, another division mode can be used.

[0076] It should be noted that all related contents of each step involved in the above method embodiment can be cited to the function description of the corresponding function module, which will not be described here.

[0077] It should be understood that the device provided by the embodiment is used to execute the above-mentioned motor control method, and therefore the same effect as the above-mentioned implementation method can be achieved.

[0078] In the case of using an integrated unit, the device can include a processing module and a storage module. When the device is applied to a vehicle, the processing module can be used to control and manage the actions of the vehicle. The storage module can be used to support the vehicle to execute the program code and the like.

[0079] The processing module can be a processor 802 or a controller, which can realize or execute various exemplary logical blocks, modules and circuits described in combination with the disclosure of the present application. The processor 802 can also be a combination of computing functions, such as one or more microprocessor combinations, a combination of digital signal processing (digital signal processing, DSP) and microprocessor, and the like. The storage module can be a memory 801.

[0080] In addition, the device provided by the embodiment of the present application can be a chip, a component or a module. The chip can include a connected processor 802 and a memory 801. The memory 801 is used to store instructions, and when the processor calls and executes the instructions, the chip can execute the motor control method provided by the above-mentioned embodiment.

[0081] The embodiment also provides a computer readable storage medium, which stores computer program code. When the computer program code runs on the computer, it makes the computer execute the above-mentioned related method steps to realize the motor control method provided by the above-mentioned embodiment.

[0082] The embodiment also provides a computer program product, which makes the computer execute the above-mentioned related steps to realize the motor control method provided by the above-mentioned embodiment when the computer program product runs on the computer.

[0083] The apparatus, the computer readable storage medium, the computer program product or the chip provided in the embodiment are used for executing the corresponding method provided in the above, and thus the beneficial effects achieved by the apparatus, the computer readable storage medium, the computer program product or the chip can refer to the beneficial effects of the corresponding method provided in the above, which will not be described here.

[0084] Through the description of the above embodiments, those skilled in the art can understand that, for the convenience and brevity of description, only the division of the above functional modules is taken as an example, and in actual application, the above functions can be completed by different functional modules according to needs, that is, the internal structure of the apparatus is divided into different functional modules to complete all or part of the functions described above.

[0085] In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other manners. For example, the apparatus embodiments described above are only schematic; the division of the modules or units is only a logical function division, and there can be another division manner in actual implementation; for example, a plurality of units or components can be combined or integrated into another apparatus, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between different units, can be indirect couplings or communication connections through some interfaces, apparatuses or units, and can be electrical, mechanical or in other forms.

[0086] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for controlling an electric motor, characterized in that, The method includes: Determine if the motor is stalled; If the motor is in the stalled state, the first to third phase current values ​​of the motor are obtained, and the zero vector adjustment value of the motor is determined based on the first to third phase current values ​​according to the pre-built zero vector adjustment allocation table. The current three-phase duty cycle of the motor is obtained, and the zero vector adjustment value is summed with the current three-phase duty cycle to obtain the final three-phase duty cycle of the motor. Based on the final three-phase duty cycle, the control signal of each phase arm of the motor is determined, so as to control the motor according to the control signal of each phase arm.

2. The method according to claim 1, characterized in that, The determination of whether the motor is in a stalled state includes: Obtain the current torque value and the current speed value of the motor; Determine whether the current torque value of the motor is greater than a preset torque threshold and whether the current speed value of the motor is less than a preset speed threshold; If the current torque value is greater than the preset torque threshold and the current speed value is less than the preset speed threshold, then the motor is determined to be in the stall state.

3. The method according to claim 1, characterized in that, The determination of the zero-vector adjustment value of the motor based on the pre-built zero-vector adjustment allocation table and the first to third phase current values ​​includes: Determine the current direction corresponding to the current value with the largest absolute value among the first to third phase current values; Calculate the first difference between the two current values ​​with the larger absolute value among the first to third phase current values; The zero vector adjustment value is matched from the pre-built zero vector adjustment allocation table based on the current direction and the first difference.

4. The method according to claim 2, characterized in that, Determining the current direction corresponding to the current value with the largest absolute value among the first to third phase current values ​​includes: Identify the current value with the largest absolute value among the first to third phase current values; Obtain the original current sign of the current value, and determine the current direction based on the original current sign.

5. The method according to claim 1, characterized in that, Before determining the zero-vector adjustment value of the motor based on the first to third phase current values ​​according to the pre-built zero-vector adjustment allocation table, the method further includes: The motor is controlled to stall to multiple target stall angles, and a target torque is applied to the motor at each target stall angle. Obtain the three-phase current and three-phase duty cycle under any set of target stall angle and target torque, and monitor the temperature difference between the target power devices between the upper and lower bridges of the target bridge arm corresponding to the current with the largest absolute value among the three-phase currents under any set of target stall angle and target torque. Based on the temperature difference value under any set of target stall angles and target torques, the three-phase duty cycle under the corresponding set of target stall angles and target torques is dynamically adjusted until the new temperature difference value meets the preset standard, and the zero vector adjustment value under the corresponding set of target stall angles and target torques is obtained according to the adjustment result. Establish a mapping relationship between the three-phase current and three-phase duty cycle under each group of target stall angle and target torque and the zero vector adjustment value under the corresponding group of target stall angle and target torque, and construct the zero vector adjustment allocation table based on the mapping relationship.

6. The method according to claim 1, characterized in that, After determining whether the motor is stalled, the process also includes: If the motor is not in the stalled state, the control signal of each phase arm of the motor is determined directly based on the current three-phase duty cycle of the motor, and the motor is controlled according to the control signal of each phase arm of the motor.

7. The method according to claim 1, characterized in that, The above-mentioned motor control method also includes: Determine whether the vehicle's current driving conditions meet the self-learning requirements; If the current driving condition meets the self-learning condition, then the target disturbance amount is applied based on the zero vector adjustment value; Monitor the direction of temperature difference change of the target power device after the target disturbance is applied, and determine the update strategy of the zero vector adjustment value based on the direction of temperature difference change; The zero vector adjustment allocation table is updated based on the updated zero vector adjustment value.

8. A control device for an electric motor, characterized in that, The device includes: The judgment module is used to determine whether the motor is in a stalled state; The determination module is used to obtain the first to third phase current values ​​of the motor if the motor is in the stall state, and determine the zero vector adjustment value of the motor based on the first to third phase current values ​​according to a pre-built zero vector adjustment allocation table. The control module is used to obtain the current three-phase duty cycle of the motor, sum the zero vector adjustment value with the current three-phase duty cycle to obtain the final three-phase duty cycle of the motor, and determine the control signal of each phase arm of the motor based on the final three-phase duty cycle, so as to control the motor according to the control signal of each phase arm.

9. A vehicle, characterized in that, The vehicle includes: the motor control method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed, implements the method as described in any one of claims 1 to 7.

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