A vehicle control method and device based on a permanent magnet motor

Abstract

The application discloses a vehicle control method and device based on a permanent magnet motor. The method comprises the following steps: in a current speed control period, when target speed and target torque instructions are not zero, determining a current torque limit value according to an actual speed of the motor, an actual working condition of the vehicle and a current torque instruction; when the target speed and the target torque instructions are not zero, determining a torque output value according to a preset maximum speed and the actual speed of the motor based on a speed control strategy and taking the current torque limit value as a limit; determining a first target current and a second target current according to the torque output value, the actual speed and a first preset corresponding relationship; wherein the first target current is a target current of a d-axis, and the second target current is a target current of a q-axis; controlling a voltage output to the motor according to the first target current and the second target current, and returning to execute a next speed control period until the motor reaches a target state. The technical scheme of the application can better control vehicle operation.

Description

Technical Field

[0001] This invention relates to the field of vehicle control technology, and in particular to a vehicle control method and device based on a permanent magnet motor. Background Technology

[0002] With the rapid development of battery technology, electric vehicles are being used more and more. The power source for electric vehicles is the electric motor, which includes permanent magnet motors. Permanent magnet motors are characterized by their small size, high power density, and high efficiency, and are increasingly favored by vehicle manufacturers.

[0003] The vehicle controller controls the operation of the permanent magnet motor, thereby controlling the vehicle's movement. When the accelerator is depressed, the vehicle controller determines the target torque based on the accelerator pedal travel, and then determines the target values ​​for the d-axis and q-axis currents based on the target torque. Based on these target values, the controller controls the conduction timing of the transistors in the circuit connected to the permanent magnet motor, thereby controlling the voltage input to the permanent magnet motor and ultimately controlling its speed, thus achieving vehicle control.

[0004] However, determining the target torque solely based on throttle travel and controlling the motor accordingly can lead to problems. For example, on relatively smooth surfaces with low friction, or when the vehicle is going downhill, the motor speed increases rapidly. In such situations, a large throttle travel and a large target torque can cause the vehicle to lose control. Alternatively, after determining the target torque, the torque command gradually adjusts to match it, and the motor is controlled according to this command each time. This can be problematic under harsh conditions, such as when the motor temperature is too high. If the torque command is too large and the motor is still controlled according to it, it could damage the motor, thus failing to provide adequate motor control. Therefore, existing vehicle controllers suffer from limitations in effectively controlling vehicle operation. Summary of the Invention

[0005] This invention provides a vehicle control method and device based on a permanent magnet motor to solve the problem that existing vehicle controllers cannot effectively control vehicle operation.

[0006] According to one aspect of the present invention, a vehicle control method based on a permanent magnet motor is provided, the vehicle control method based on a permanent magnet motor comprising:

[0007] In the current speed control cycle, when the target speed and target torque command are not zero, the current torque limit is determined based on the actual speed of the motor, the actual operating conditions of the vehicle, and the current torque command.

[0008] When the target speed and target torque commands are not zero, based on the speed control strategy, the torque output value is determined according to the preset maximum speed and the actual speed of the motor, with the current torque limit as the limit;

[0009] The first target current and the second target current are determined based on the torque output value, the actual speed, and the first preset correspondence; wherein, the first target current is the target current of the d-axis, and the second target current is the target current of the q-axis;

[0010] The voltage output to the motor is controlled according to the first target current and the second target current, and the process returns to execute the next speed control cycle until the motor reaches the target state.

[0011] Optionally, the current torque limit is determined based on the actual speed of the motor, the actual operating conditions of the vehicle, and the current torque command, including:

[0012] When the vehicle is not braking, the current torque limit is determined based on the first electric torque limit, the second electric torque limit, and the current torque command; wherein, the first electric torque limit is the electric torque limit corresponding to the actual speed of the motor, and the second electric torque limit is the electric torque limit corresponding to the actual operating condition of the vehicle;

[0013] When the vehicle brakes, a current torque limit is determined based on a first braking torque limit, a second braking torque limit, and a current torque command; wherein the first braking torque limit is the braking torque limit corresponding to the actual speed, and the second braking torque limit is the braking torque limit corresponding to the actual operating condition.

[0014] Optionally, before determining the current torque limit based on the actual speed of the motor, the actual operating conditions of the vehicle, and the current torque command, the method further includes:

[0015] The preset maximum speed is determined based on the target torque command and the direction of motor speed;

[0016] The current torque command for the current speed control cycle is determined based on the previous torque command and torque change slope of the previous speed control cycle.

[0017] Optionally, the speed control strategy, which determines the torque output value based on the current torque limit and a preset maximum speed and the actual speed of the motor, includes:

[0018] Based on the speed control strategy, the output value of the speed control strategy is determined according to the preset maximum speed and the actual speed of the motor;

[0019] When the absolute value of the output value of the speed control strategy is greater than the absolute value of the current torque limit, the current torque limit is set as the torque output value.

[0020] When the absolute value of the output value of the speed control strategy is less than or equal to the absolute value of the current torque limit, the output value of the speed control strategy is the torque output value.

[0021] Optionally, the current torque limit is determined based on the first electric torque limit, the second electric torque limit, and the current torque command, including:

[0022] The minimum value among the first electric torque limit, the second electric torque limit, and the current torque command is taken as the current torque limit;

[0023] The current torque limit is determined based on the first braking torque limit, the second braking torque limit, and the current torque command, including:

[0024] The torque value corresponding to the minimum value among the absolute values ​​of the first braking torque limit, the second braking torque limit, and the current torque command is taken as the current torque limit.

[0025] Optionally, before determining the current torque limit based on the first electric torque limit, the second electric torque limit, and the current torque command, the method further includes:

[0026] The first electric torque limit is determined based on the actual rotational speed and the second preset correspondence; wherein, the second preset correspondence is the correspondence between the actual rotational speed and the first electric torque limit.

[0027] The second electric torque limit is determined based on the actual operating conditions and the third preset correspondence; wherein, the third preset correspondence is the correspondence between the actual operating conditions and the second electric torque limit.

[0028] Before determining the current torque limit based on the first braking torque limit, the second braking torque limit, and the current torque command, the method further includes:

[0029] The first braking torque limit is determined based on the actual rotational speed and the fourth preset correspondence; wherein, the fourth preset correspondence is the correspondence between the actual rotational speed and the first braking torque limit.

[0030] The second braking torque limit is determined based on the actual operating conditions and the fifth preset correspondence; wherein, the fifth preset correspondence is the correspondence between the actual operating conditions and the second braking torque limit.

[0031] Optionally, based on the speed control strategy, the output value of the speed control strategy is determined according to the preset maximum speed and the actual speed of the motor, including:

[0032] If the current speed control cycle is the first speed control cycle after the target speed and the target torque command change from zero to non-zero, then the actual speed of the motor is taken as the current speed command of the current speed control cycle;

[0033] If the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and the target torque command change from zero to non-zero, then when the difference between the absolute value of the current speed command and the absolute value of the preset maximum speed is less than the difference threshold, the sum of the previous speed command of the previous speed control cycle and the preset acceleration is taken as the current speed command of the current speed control cycle.

[0034] The difference between the current speed command and the actual speed in the current speed control cycle is multiplied by the speed proportional coefficient to obtain the speed proportional term for the current speed control cycle.

[0035] If the current speed control cycle is the first speed control cycle after the target speed and the target torque command change from zero to non-zero, then the output value of the speed control strategy of the previous speed control cycle is used as the speed integral term of the current speed control cycle.

[0036] If the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and the target torque command change from zero to non-zero, then the product of the speed proportional term of the current speed control cycle and the speed integral coefficient, and the sum of the speed integral term of the previous speed control cycle, are used as the speed integral term of the current speed control cycle.

[0037] The sum of the proportional term of the current speed control cycle and the integral term of the current speed control cycle is used as the output value of the speed control strategy.

[0038] Optionally, controlling the voltage output to the motor based on the first target current and the second target current includes:

[0039] The difference between the first target current and the first actual current is multiplied by the first current proportional coefficient to obtain the first current proportional term of the current speed control cycle.

[0040] Multiply the first current proportional term of the current speed control cycle by the first current integral coefficient, and add the first current integral term of the previous speed control cycle to obtain the first current integral term of the current speed control cycle.

[0041] The sum of the first current proportional term and the first current integral term of the current speed control cycle is used as the first control quantity;

[0042] The difference between the second target current and the second actual current is multiplied by the second current proportional coefficient to obtain the second current proportional term for the current speed control cycle.

[0043] Multiply the second current proportional term of the current speed control cycle by the second current integral coefficient, and add the second current integral term of the previous speed control cycle to obtain the second current integral term of the current speed control cycle.

[0044] The sum of the second current proportional term and the second current integral term of the current speed control cycle is used as the second control quantity;

[0045] The voltage output to the motor is controlled according to the first control quantity and the second control quantity.

[0046] Optionally, before determining the first target current and the second target current based on the torque output value, the actual rotational speed, and the first preset correspondence, the method further includes:

[0047] In the current speed control cycle, when the target speed and target torque command are both zero, the torque output value is determined based on the speed control strategy, according to the target speed and the actual speed.

[0048] When the target speed and target torque commands are not zero, the motor reaches the target state, including:

[0049] The difference between the actual torque of the motor and the target torque command is less than a first threshold.

[0050] When the target speed and target torque commands are zero, the motor reaches the target state, including:

[0051] The absolute value of the actual rotational speed of the motor is less than the second threshold for a preset duration.

[0052] Optionally, in the current speed control cycle, when the target speed and target torque commands are zero, the torque output value is determined based on the speed control strategy, according to the target speed and the actual speed, including:

[0053] If the current speed control cycle is the first speed control cycle after the target speed and the target torque command change from non-zero to zero, then the actual speed of the motor is taken as the current speed command of the current speed control cycle;

[0054] If the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and the target torque command change from non-zero to zero, then when the absolute value of the current speed command is less than the difference threshold, the difference between the previous speed command of the previous speed control cycle and the preset deceleration is taken as the current speed command of the current speed control cycle.

[0055] The difference between the current speed command and the actual speed in the current speed control cycle is multiplied by the speed proportional coefficient to obtain the speed proportional term for the current speed control cycle.

[0056] If the current speed control cycle is the first speed control cycle after the target speed and the target torque command change from non-zero to zero, then the output value of the speed control strategy of the previous speed control cycle is used as the speed integral term of the current speed control cycle.

[0057] If the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and the target torque command change from non-zero to zero, then the product of the speed proportional term of the current speed control cycle and the speed integral coefficient, and the sum of the speed integral term of the previous speed control cycle, are used as the speed integral term of the current speed control cycle.

[0058] The sum of the proportional term of the current speed control cycle and the integral term of the current speed control cycle is used as the torque output value.

[0059] According to another aspect of the present invention, a vehicle control device based on a permanent magnet motor is provided, the vehicle control device based on a permanent magnet motor comprising:

[0060] The limit determination module is used to determine the current torque limit based on the actual motor speed, the actual operating conditions of the vehicle, and the current torque command during the current speed control cycle, when the target speed and target torque command are not zero.

[0061] The torque output value determination module is used to determine the torque output value based on the speed control strategy, with the current torque limit value as a limit, and according to the preset maximum speed and the actual speed of the motor when the target speed and the target torque command are not zero.

[0062] The target current determination module is used to determine a first target current and a second target current based on the torque output value, the actual speed, and a first preset correspondence; wherein, the first target current is the target current of the d-axis, and the second target current is the target current of the q-axis;

[0063] The control module is used to control the voltage output to the motor according to the first target current and the second target current, and return to execute the next speed control cycle until the motor reaches the target state.

[0064] The technical solution of this invention, in the current speed control cycle, when the target speed and target torque command are not zero, determines the current torque limit based on the actual motor speed, the actual vehicle operating conditions, and the current torque command. This ensures that the determination of the current torque limit combines the actual motor speed and the actual vehicle operating conditions, avoiding situations where the current torque limit is determined directly based on the current torque command, leading to a discrepancy between the determined current torque limit and the actual motor speed or vehicle operating conditions (e.g., setting a large current torque limit even when the motor temperature is high). This improves the accuracy of the current torque limit determination, facilitating improved motor control accuracy and better vehicle operation control. When the target speed and target torque command are not zero, based on the speed control strategy, with the current torque limit as the limit, the torque output value is determined according to the preset maximum speed and the actual motor speed. A first target current and a second target current are determined based on the torque output value, the actual speed, and a first preset correspondence. The voltage output to the motor is controlled based on the first target current and the second target current. This allows the motor speed to be increased when the actual motor speed is low (i.e., the actual speed is less than the preset maximum speed), making the motor speed close to or equal to the preset maximum speed, thus ensuring motor operating efficiency. When the actual motor speed is high, i.e., greater than the preset maximum speed, the actual motor speed can be reduced. This ensures that the actual motor speed is close to or equal to the preset maximum speed. When ground friction is low, or when the vehicle is going downhill, this avoids the problem of the motor speed increasing too much if the motor voltage is controlled only according to the current torque command, which could lead to loss of vehicle control. This allows for better control of vehicle operation.

[0065] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0066] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0067] Figure 1 This is a flowchart of a vehicle control method based on a permanent magnet motor provided in an embodiment of the present invention;

[0068] Figure 2 This is a flowchart of another vehicle control method based on a permanent magnet motor provided in an embodiment of the present invention;

[0069] Figure 3This is a flowchart of another vehicle control method based on a permanent magnet motor provided in an embodiment of the present invention;

[0070] Figure 4 This is a schematic diagram of a vehicle control device based on a permanent magnet motor provided in an embodiment of the present invention. Detailed Implementation

[0071] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0072] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0073] This invention provides a vehicle control method based on a permanent magnet motor, which can be executed by a vehicle control device based on a permanent magnet motor. For example, the vehicle is an electric vehicle, which may include electric industrial vehicles such as electric sightseeing vehicles, electric forklifts, and electric aerial work platforms. The vehicle includes a permanent magnet motor, and the vehicle controller may include a vehicle control device based on a permanent magnet motor.

[0074] Figure 1 This is a flowchart of a vehicle control method based on a permanent magnet motor provided in an embodiment of the present invention, with reference to... Figure 1 Vehicle control methods based on permanent magnet motors include:

[0075] S110. In the current speed control cycle, when the target speed and target torque commands are not zero, determine the current torque limit based on the actual speed of the motor, the actual operating conditions of the vehicle, and the current torque command.

[0076] After the vehicle starts, a speed control cycle is executed cyclically. In each speed control cycle, a control signal is output. This control signal can be used to control the gate of the transistor in the voltage circuit connected to the motor (e.g., the inverter circuit), thereby controlling the voltage applied to the motor. Each output of a control signal constitutes one speed control cycle. The target speed is the target speed of the motor. When the accelerator (throttle) is released, both the target speed and target torque commands are zero; when the accelerator is not released, both the target speed and target torque commands are not zero.

[0077] The motor is a permanent magnet motor. The actual operating conditions of the vehicle include whether the motor temperature exceeds a first temperature threshold, whether the vehicle controller temperature exceeds a second temperature threshold, whether the vehicle battery voltage is lower than a first voltage threshold, whether the bus voltage connected to the vehicle battery exceeds the second voltage threshold, and whether the remaining battery charge is lower than a charge threshold. For example, when the actual operating conditions include the motor temperature exceeding the first temperature threshold, the current torque limit can be controlled to be lower to prevent the motor torque from being too high and causing the motor temperature to rise further.

[0078] The current torque command is the torque command corresponding to the current speed control cycle. The current torque command can be determined based on the previous torque command and the torque change slope of the previous speed control cycle. The torque change slope can be the rate of change of torque over time. That is, the torque command changes periodically until the current torque command equals the target torque command. When the accelerator is not released, and the target speed and target torque command are not zero, the target speed is related to the accelerator's stroke, and the target torque command is also related to the accelerator's stroke. For example, the greater the accelerator stroke, the greater the corresponding target speed of the motor. For example, when the accelerator stroke is 100%, it means the accelerator is fully depressed.

[0079] Specifically, in the current speed control cycle, when the target speed and target torque command are not zero, the current torque limit is determined based on the actual motor speed, the actual vehicle operating conditions, and the current torque command. This ensures that the current torque limit is related to the actual motor speed, actual operating conditions, and current torque command. For example, if the torque limit corresponding to the actual motor speed, or the torque limit corresponding to the actual operating conditions, or the torque limit corresponding to the current torque command is small, the current torque limit can be smaller. In this way, the determination of the current torque limit incorporates both the actual motor speed and the actual vehicle operating conditions, avoiding situations where the current torque limit is determined directly based on the current torque command, leading to a discrepancy between the determined current torque limit and the actual motor speed or the actual vehicle operating conditions. This improves the accuracy of the current torque limit determination, facilitating improved motor control accuracy and ultimately enabling better vehicle operation control.

[0080] S120. When the target speed and target torque commands are not zero, based on the speed control strategy, the torque output value is determined according to the preset maximum speed and the actual speed of the motor, with the current torque limit as the limit.

[0081] The speed control strategy can be a proportional-integral (PI) control strategy.

[0082] Specifically, when the target speed and target torque commands are not zero, the current speed command changes periodically until it equals or approaches the preset maximum speed. During the current speed control cycle, the current speed command and the actual motor speed are input to the speed control strategy to obtain its output value. Based on the output value of the speed control strategy and the current torque limit, the torque output value is determined. This ensures the torque output value will not exceed the current torque limit, preventing it from becoming excessively large. This avoids situations where the current torque command is too small, or the torque limit corresponding to the actual motor speed is too small, or the torque limit corresponding to the actual vehicle operating conditions is too small, resulting in an excessively large torque output value. This improves the accuracy of motor control and allows for better vehicle operation control.

[0083] By inputting the current speed command and the actual motor speed into the speed control strategy, the current speed command changes periodically until it equals or approaches the preset maximum speed. The speed control strategy outputs a value targeting the preset maximum speed, causing the actual motor speed to change towards it. When the actual motor speed is low (less than the preset maximum speed), the motor speed can be increased to bring it close to or equal to the preset maximum speed, ensuring motor efficiency. Conversely, when the actual motor speed is high (greater than the preset maximum speed), the actual motor speed can be decreased. This ensures the actual motor speed remains close to or equal to the preset maximum speed, preventing excessive speeds. In situations with low ground friction or when the vehicle is going downhill, this avoids the problem of excessively high motor speeds, which could lead to loss of vehicle control if the motor voltage is controlled solely based on the current torque command. This allows for better vehicle control.

[0084] S130. Determine the first target current and the second target current based on the torque output value, the actual speed and the first preset correspondence; wherein, the first target current is the target current of the d-axis and the second target current is the target current of the q-axis.

[0085] The current required torque can be determined based on the torque output value. The current required torque is the ratio of the torque output value to the maximum output value, multiplied by the maximum required torque. The maximum output value is the current torque limit, and the maximum required torque is the maximum torque that the motor can achieve, which is the maximum torque that the manufacturer specified when the motor left the factory.

[0086] The first preset correspondence is the correspondence between the current required torque, the actual speed, the first target current, and the second target current.

[0087] Specifically, in the current speed control cycle, by substituting the current required torque corresponding to the torque output value and the actual speed of the motor into the first preset correspondence, the corresponding first target current and second target current can be determined. For example, a set of parameters (a torque output value and an actual speed) corresponds to a first target current and a second target current, and in different sets of parameters, at least one of the current required torque and the actual speed is different.

[0088] For example, before vehicle application, multiple preset torques and multiple preset speeds can be set. Under the preset torque, when the motor is at each preset speed, the target current of the d-axis is controlled as the first preset current, and the target current of the q-axis is controlled as the second preset current. The voltage output to the motor is controlled according to the first preset current and the second preset current to obtain the motor torque value. If the motor torque value differs significantly from the preset torque, the first preset current and the second preset current are adjusted until the motor torque value differs significantly from the preset torque. The first preset current at this time is taken as the first target current, and the second preset current is taken as the second target current, thereby determining the first preset correspondence. The first preset correspondence is stored in the vehicle's memory, so that when the vehicle is applied, the first target current and the second target current can be determined according to the current required torque, the actual speed, and the first preset correspondence corresponding to the torque output value.

[0089] S140. Control the voltage output to the motor according to the first target current and the second target current, and return to execute the next speed control cycle until the motor reaches the target state.

[0090] Specifically, the control quantity of the d-axis is output based on the first target current and the actual current of the d-axis, and the control quantity of the q-axis is output based on the second target current and the actual current of the q-axis. After coordinate transformation of the control quantities of the d-axis and q-axis, pulse width modulation is performed to obtain a control signal. The control signal is output to the gate of the transistor in the voltage circuit (e.g., inverter circuit) connected to the motor to control the voltage applied to the motor. Each output of the control signal completes one speed control cycle. After the current speed control cycle is completed, the process returns to step S110 to execute the next speed control cycle until the motor reaches the target state. The motor reaching the target state is, for example, when the actual speed of the motor is close to or equal to the target speed, or when the actual torque of the motor is close to or equal to the target torque command; however, this is not limited here.

[0091] The technical solution of this embodiment, in the current speed control cycle, when the target speed and target torque command are not zero, determines the current torque limit based on the actual motor speed, the actual vehicle operating conditions, and the current torque command. This ensures that the determination of the current torque limit combines the actual motor speed and the actual vehicle operating conditions, avoiding situations where the current torque limit is determined directly based on the current torque command, resulting in a discrepancy between the determined current torque limit and the actual motor speed or vehicle operating conditions (e.g., setting a large current torque limit even when the motor temperature is high). This improves the accuracy of the current torque limit determination, facilitating improved motor control accuracy and better vehicle operation control. When the target speed and target torque command are not zero, based on the speed control strategy, with the current torque limit as the limit, the torque output value is determined according to the preset maximum speed and the actual motor speed. The first target current and the second target current are determined based on the torque output value, the actual speed, and a first preset correspondence. The voltage output to the motor is controlled based on the first target current and the second target current. This allows the motor speed to be increased when the actual motor speed is low (i.e., the actual speed is less than the preset maximum speed), making the motor speed close to or equal to the preset maximum speed, thus ensuring motor operating efficiency. When the actual motor speed is high, i.e., greater than the preset maximum speed, the actual motor speed can be reduced. This ensures that the actual motor speed is close to or equal to the preset maximum speed. When ground friction is low, or when the vehicle is going downhill, this avoids the problem of the motor speed increasing too much if the motor voltage is controlled only according to the current torque command, which could lead to loss of vehicle control. This allows for better control of vehicle operation.

[0092] Based on the above technical solution, optionally, the current torque limit is determined according to the actual speed of the motor, the actual operating conditions of the vehicle, and the current torque command, including:

[0093] Step a01: When the vehicle is not braking, determine the current torque limit based on the first electric torque limit, the second electric torque limit, and the current torque command; wherein, the first electric torque limit is the electric torque limit corresponding to the actual speed of the motor, and the second electric torque limit is the electric torque limit corresponding to the actual operating conditions of the vehicle.

[0094] In this context, "not braking" refers to the vehicle accelerating or moving at a constant speed, meaning the accelerator's travel increases or remains constant. "Braking" refers to the vehicle decelerating, meaning the accelerator's travel decreases or it is released. For example, a greater accelerator travel corresponds to a higher target motor speed. When the target speed and target torque commands are not zero, vehicle braking indicates that the accelerator is still depressed, but its travel decreases, meaning the accelerator is not released and the vehicle is decelerating. Therefore, whether the vehicle is braking can be determined based on changes in the accelerator's travel.

[0095] Specifically, the actual motor speed corresponds to the first electric torque limit. The actual speed can be substituted into this correspondence to determine the first electric torque limit. Similarly, the actual vehicle operating conditions correspond to the second electric torque limit. The actual operating conditions can be substituted into this correspondence to determine the second electric torque limit. By determining the current torque limit based on the first electric torque limit, the second electric torque limit, and the current torque command when the target speed and target torque command are not zero and the vehicle is not braking, the current torque limit can be determined by combining the actual motor speed, the actual vehicle operating conditions, and the current torque command. This avoids directly determining the current torque limit based on the current torque command, which could lead to discrepancies between the determined current torque limit and the actual motor speed or the actual vehicle operating conditions. This improves the accuracy of the current torque limit determination, facilitating better motor control and ultimately enabling better vehicle operation control.

[0096] Step a02: When the vehicle is braking, determine the current torque limit based on the first braking torque limit, the second braking torque limit, and the current torque command; wherein, the first braking torque limit is the braking torque limit corresponding to the actual speed, and the second braking torque limit is the braking torque limit corresponding to the actual operating condition.

[0097] Specifically, the first braking torque limit corresponds to the actual speed of the motor. The actual speed of the motor can be substituted into the correspondence between the first braking torque limit and the actual speed to determine the first braking torque limit. The actual operating conditions of the vehicle correspond to the second braking torque limit. The actual operating conditions can be substituted into the correspondence between the actual operating conditions and the second braking torque limit to determine the second braking torque limit. By determining the current torque limit based on the first braking torque limit, the second braking torque limit, and the current torque command when the target speed and target torque command are not zero, during vehicle braking, the determination of the current torque limit incorporates both the actual speed of the motor and the actual operating conditions of the vehicle. This avoids situations where the current torque limit is determined directly based on the current torque command, leading to discrepancies between the determined current torque limit and the actual speed of the motor or the actual operating conditions of the vehicle (e.g., setting a large current torque limit even when the motor temperature is high). This improves the accuracy of the current torque limit determination, facilitating improved motor control accuracy and ultimately better vehicle operation control.

[0098] Optionally, the current torque limit is determined based on the first electric torque limit, the second electric torque limit, and the current torque command, including:

[0099] The minimum value among the first electric torque limit, the second electric torque limit, and the current torque command is used as the current torque limit.

[0100] Specifically, by using the minimum value among the first electric torque limit, the second electric torque limit, and the current torque command as the current torque limit, the current torque limit is prevented from becoming excessively large. This ensures that the current torque limit can be smaller when the torque limit corresponding to the actual motor speed, the actual operating condition, or the current torque command is relatively small. This avoids situations where the actual vehicle speed does not match the current torque limit, and also prevents situations where the current speed limit is too large when the actual vehicle operating condition is poor (e.g., the motor temperature exceeds the first temperature threshold). Furthermore, it also prevents situations where the current speed limit is too large when the accelerator stroke is short.

[0101] Optionally, the current torque limit is determined based on the first braking torque limit, the second braking torque limit, and the current torque command, including:

[0102] The torque value corresponding to the minimum value among the absolute values ​​of the first braking torque limit, the second braking torque limit, and the current torque command is taken as the current torque limit.

[0103] Specifically, by using the torque value corresponding to the minimum of the absolute values ​​of the first braking torque limit, the second braking torque limit, and the current torque command as the current torque limit, the absolute value of the current torque limit is not too large, thus avoiding a mismatch between the actual speed of the vehicle and the current torque limit. It also avoids the situation where the absolute value of the current speed limit is too large when the actual operating conditions of the vehicle are poor (e.g., the motor temperature is greater than the first temperature threshold).

[0104] Optionally, before determining the current torque limit based on the first electric torque limit, the second electric torque limit, and the current torque command, the vehicle control method based on the permanent magnet motor further includes:

[0105] Step a1: Determine the first electric torque limit based on the actual rotational speed and the second preset correspondence; wherein, the second preset correspondence is the correspondence between the actual rotational speed and the first electric torque limit.

[0106] For example, Table 1 is a schematic table of the second preset correspondence. As shown in Table 1, the actual speed corresponds one-to-one with the first electric torque limit. After determining the actual speed of the motor, the actual speed of the motor can be substituted into the second preset correspondence to determine the corresponding first electric torque limit. When the actual speed of the motor is not stored in the table, the first electric torque limit corresponding to the actual speed of the motor can be determined by interpolation based on the first electric torque limit corresponding to two adjacent actual speeds in the table. For example, when the actual speed of the motor is determined to be 1200 rpm, the first electric torque limit corresponding to the actual speed of the motor at 1200 rpm can be determined by interpolation based on the first electric torque limit of 180 N·m corresponding to 1000 rpm and the first electric torque limit of 160 N·m corresponding to 1400 rpm.

[0107] Table 1. Schematic diagram of the second preset correspondence.

[0108]

[0109] Step a2: Determine the second electric torque limit based on the actual operating conditions and the third preset correspondence; wherein, the third preset correspondence is the correspondence between the actual operating conditions and the second electric torque limit.

[0110] For example, the actual operating conditions of the vehicle include whether the motor temperature is greater than a first temperature threshold, whether the vehicle controller temperature is greater than a second temperature threshold, whether the vehicle battery voltage is less than a first voltage threshold, whether the bus voltage connected to the vehicle battery is greater than the second voltage threshold, and whether the remaining charge of the vehicle battery is less than a charge threshold. For instance, when the motor temperature is less than or equal to the first temperature threshold, the vehicle controller temperature is less than or equal to the second temperature threshold, the vehicle battery voltage is greater than or equal to the first voltage threshold, and the remaining charge of the vehicle battery is greater than or equal to the charge threshold, the corresponding second electric torque limit is the maximum. When at least one of the following conditions is met, the actual operating conditions of the vehicle are poor, and the corresponding second electric torque limit is small (less than the maximum second electric torque limit): the motor temperature is greater than the first temperature threshold, the vehicle controller temperature is greater than the second temperature threshold, the vehicle battery voltage is less than the first voltage threshold, and the remaining charge of the vehicle battery is less than the charge threshold.

[0111] For example, the second electric torque limit is minimized when the motor temperature is greater than a first temperature threshold, the vehicle controller temperature is greater than a second temperature threshold, the vehicle battery voltage is less than a first voltage threshold, and the remaining charge of the vehicle battery is less than a charge threshold.

[0112] In this way, a corresponding second electric torque limit can be determined based on the actual operating conditions of the vehicle. This avoids the current torque limit being too high when the actual operating conditions of the vehicle are poor.

[0113] Optionally, before determining the current torque limit based on the first braking torque limit, the second braking torque limit, and the current torque command, the vehicle control method based on the permanent magnet motor further includes:

[0114] Step b1: Determine the first braking torque limit based on the actual rotational speed and the fourth preset correspondence; wherein, the fourth preset correspondence is the correspondence between the actual rotational speed and the first braking torque limit.

[0115] For example, Table 2 is a schematic table of the fourth preset correspondence. As shown in Table 2, the actual speed corresponds one-to-one with the first braking torque limit. After determining the actual speed of the motor, the actual speed of the motor can be substituted into the fourth preset correspondence to determine the corresponding first braking torque limit. When the actual speed of the motor is not stored in the table, the first braking torque limit corresponding to the actual speed of the motor can be determined by interpolation based on the first braking torque limit corresponding to two adjacent actual speeds in the table. The values ​​of the first braking torque limit shown in Table 2 are unsigned numerical values, that is, the absolute values ​​of the first braking torque limit. The first braking torque limit has the opposite sign to the first electric torque limit, that is, the first electric torque limit is positive and the first braking torque limit is negative, or the first electric torque limit is negative and the first braking torque limit is positive.

[0116] Table 2. Schematic diagram of the fourth preset correspondence.

[0117]

[0118] Step b2: Determine the second braking torque limit based on the actual working conditions and the fifth preset correspondence; wherein, the fifth preset correspondence is the correspondence between the actual working conditions and the second braking torque limit.

[0119] For example, the actual operating conditions of the vehicle include whether the motor temperature exceeds a first temperature threshold, whether the vehicle controller temperature exceeds a second temperature threshold, whether the vehicle battery voltage is less than a first voltage threshold, whether the bus voltage connected to the vehicle battery exceeds a second voltage threshold, and whether the remaining battery charge is less than a charge threshold. For instance, the bus voltage connected to the vehicle battery has a significant impact on braking torque. When the actual operating condition is that the bus voltage connected to the battery is less than or equal to the second voltage threshold, the absolute value of the second braking torque limit is larger; conversely, when the actual operating condition is that the bus voltage connected to the battery is greater than the second voltage threshold, the absolute value of the second braking torque limit is smaller. This ensures that when the bus voltage is too high, the absolute value of the current torque limit is smaller, avoiding risks such as motor overheating.

[0120] Based on the above technical solutions, Figure 2 This is a flowchart of another vehicle control method based on a permanent magnet motor provided in an embodiment of the present invention. Optionally, refer to... Figure 2 Vehicle control methods based on permanent magnet motors include:

[0121] S210. In the current speed control cycle, when the target speed and target torque commands are not zero, determine the preset maximum speed based on the target torque command and the motor speed direction.

[0122] Specifically, when the motor's rotation direction is positive (e.g., the direction the motor rotates when the vehicle is moving forward), the preset maximum speed is a positive value; when the motor's rotation direction is negative (reverse), the preset maximum speed is a negative value. There is a correspondence between the target torque command and the absolute value of the preset maximum speed. By substituting the target torque command into this correspondence, the absolute value of the preset maximum speed can be determined. Therefore, the preset maximum speed can be determined based on the target torque command and the motor's rotation direction. It is not limited here that the absolute value of the preset maximum speed can be the same or different when the target torque command is the same but the motor's rotation direction is different.

[0123] S220. Determine the current torque command for the current speed control cycle based on the previous torque command and torque change slope of the previous speed control cycle.

[0124] Specifically, the specific value of each torque change (positive or negative) can be determined based on the torque change slope and the interval between two speed control cycles. Adding the previous torque command from the previous speed control cycle to this specific value yields the current torque command for the current speed control cycle. For example, when the torque change slope is positive, the specific value of each torque change is positive; when the torque change slope is negative, the specific value of each torque change is negative. This causes the current torque command to change periodically, resulting in a periodic change in the torque output value until the motor reaches the target state. Specifically, the torque change slope is positive when the vehicle is moving forward or accelerating, and negative when the vehicle is decelerating.

[0125] Alternatively, if the torque change slope is unsigned (i.e., positive), the specific value of each torque change can be determined based on the torque change slope and the interval between two speed control cycles. This specific value is also positive. When the vehicle is accelerating, the torque command of the previous speed control cycle is added to the specific value of each torque change to obtain the current torque command for the current speed control cycle. When the vehicle is decelerating, the torque command of the previous speed control cycle is subtracted from the specific value of each torque change to obtain the current torque command for the current speed control cycle.

[0126] S230. Determine whether the vehicle is braking. If not, proceed to step S240; if yes, proceed to step S250.

[0127] S240. Determine the current torque limit based on the first electric torque limit, the second electric torque limit, and the current torque command.

[0128] S250. Determine the current torque limit based on the first braking torque limit, the second braking torque limit, and the current torque command.

[0129] S260. When the target speed and target torque commands are not zero, based on the speed control strategy, the torque output value is determined according to the preset maximum speed and the actual speed of the motor, with the current torque limit as the limit.

[0130] S270. Determine the first target current and the second target current based on the torque output value, the actual speed and the first preset correspondence; wherein, the first target current is the target current of the d-axis and the second target current is the target current of the q-axis.

[0131] S280: Control the voltage output to the motor according to the first target current and the second target current, and return to execute the next speed control cycle until the motor reaches the target state.

[0132] Based on the above technical solutions, optionally, based on a speed control strategy, and with the current torque limit as a constraint, the torque output value is determined according to the preset maximum speed and the actual speed of the motor, including:

[0133] Step c1: Based on the speed control strategy, determine the output value of the speed control strategy according to the preset maximum speed and the actual speed of the motor.

[0134] Specifically, the speed control strategy is a proportional-integral control strategy. The preset maximum speed is the target value, and the actual speed of the motor is the feedback value. The input to the speed control strategy yields the output value of the speed control strategy. This allows the motor speed to be close to or equal to the preset maximum speed when the voltage input to the motor is controlled according to the output value of the speed control strategy. This ensures the motor's operating efficiency while preventing the motor speed from being too high.

[0135] Step c2: When the absolute value of the output value of the speed control strategy is greater than the absolute value of the current torque limit, set the current torque limit as the torque output value.

[0136] Specifically, by setting the current torque limit as the torque output value when the absolute value of the speed control strategy output value is greater than the absolute value of the current torque limit, the torque output value can be limited within the current torque limit. This ensures that the torque output value is less than or equal to the current torque limit, preventing the torque output value from becoming too large. This avoids situations where the current torque command is small, or the torque limit corresponding to the actual motor speed is small, or the torque limit corresponding to the actual vehicle operating conditions is small, resulting in an excessively large torque output value, thereby improving the accuracy of motor control.

[0137] Step c3: When the absolute value of the output value of the speed control strategy is less than or equal to the absolute value of the current torque limit, set the output value of the speed control strategy to the torque output value.

[0138] Specifically, when the absolute value of the output value of the speed control strategy is less than or equal to the absolute value of the current torque limit, the output value of the speed control strategy can be used as the torque output value normally. This makes it possible to control the voltage output to the motor according to the torque output value, and the motor speed can be based on the preset maximum speed to ensure the motor's operating efficiency.

[0139] Optionally, based on the speed control strategy, the output value of the speed control strategy is determined according to the preset maximum speed and the actual speed of the motor, including:

[0140] Step c11: If the current speed control cycle is the first speed control cycle after the target speed and target torque commands change from zero to non-zero, then the actual speed of the motor is taken as the current speed command of the current speed control cycle.

[0141] Specifically, in the first speed control cycle after the target speed and target torque commands change from zero to non-zero, the actual speed of the motor is used as the current speed command for the current speed control cycle, so that the deviation between the actual speed of the motor and the current speed command is zero. This avoids the situation where the current speed command changes too much when the target speed and target torque commands change too much, which would lead to an excessive change in the actual speed of the motor and cause vehicle instability.

[0142] Step c12: If the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and target torque commands change from zero to non-zero, then when the difference between the absolute value of the current speed command and the absolute value of the preset maximum speed is less than the difference threshold, the sum of the previous speed command of the previous speed control cycle and the preset acceleration is taken as the current speed command of the current speed control cycle.

[0143] The preset acceleration can be positive or negative. When the accelerator's stroke increases, the vehicle accelerates and the preset acceleration is positive. When the accelerator's stroke decreases, the vehicle decelerates and the preset acceleration is negative.

[0144] Specifically, when the current speed control cycle is outside the first speed control cycle after the target speed and target torque commands change from zero to non-zero, in the current speed control cycle, the sum of the previous speed command from the previous speed control cycle and the preset acceleration is used as the current speed command for the current speed control cycle. This causes the current speed command to change periodically until it approaches or equals the preset maximum speed, i.e., the difference between the absolute value of the current speed command and the absolute value of the preset maximum speed is less than a difference threshold. After the difference between the absolute value of the current speed command and the absolute value of the preset maximum speed is less than the difference threshold, the current speed command can remain unchanged, allowing the vehicle to run at a constant speed.

[0145] Step c13: Multiply the difference between the current speed command and the actual speed in the current speed control cycle by the speed proportional coefficient to obtain the speed proportional term for the current speed control cycle.

[0146] Specifically, the difference between the current speed command and the actual speed determines the deviation between the actual motor speed and the current speed command. Multiplying this deviation by the speed proportionality coefficient yields the speed proportional term for the current speed control cycle. For example, if the current speed command is Vref, the actual speed is Vspd, and the speed proportionality coefficient is K... P1 For example, if the current speed control cycle is the j-th speed control cycle (the j-th speed control cycle counted from when the vehicle starts), then the speed proportional term U of the current speed control cycle... P1（j） For U P1（j） =(Vref-Vspd)×K P1 Where j is an integer greater than 1. If the current speed control cycle is the first speed control cycle after the target speed and target torque commands change from zero to non-zero, and the current speed command is the same as the actual speed, then the speed proportional term is zero.

[0147] Step c14: If the current speed control cycle is the first speed control cycle after the target speed and target torque commands change from zero to non-zero, then the output value of the speed control strategy of the previous speed control cycle is used as the speed integral term of the current speed control cycle.

[0148] Specifically, in the first speed control cycle after the target speed and target torque commands change from zero to non-zero, the output value of the speed control strategy of the previous speed control cycle is used as the speed integral term of the current speed control cycle. Since the speed proportional term of the current speed control cycle is zero, the output value of the speed control strategy of the current speed control cycle is the same as the output value of the speed control strategy of the previous speed control cycle, which can avoid sudden changes in the motor voltage.

[0149] Step c15: If the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and target torque commands change from zero to non-zero, then multiply the speed proportional term of the current speed control cycle by the speed integral coefficient, and add the speed integral term of the previous speed control cycle to obtain the speed integral term of the current speed control cycle.

[0150] Specifically, by multiplying the proportional term of the current speed control cycle by the integral term of the speed, and adding the integral term of the speed control cycle from the previous speed control cycle, the cumulative deviation can be determined, which is the integral term of the current speed control cycle. For example, the integral term of the previous speed control cycle might be U. i1（j-1） The integral coefficient of rotational speed is K. i1 The speed integral term U in the current speed control cycle i1（j） For U i1（j） =U i1（j-1） +U P1（j） ×K i1 .

[0151] Step c16: The sum of the proportional term of the current speed control cycle and the integral term of the current speed control cycle is used as the output value of the speed control strategy.

[0152] Specifically, the sum of the proportional term and the integral term of the current speed control cycle is used as the output value of the speed control strategy for the current speed control cycle. For example, the output value V of the speed control strategy for the current speed control cycle is... out（j） For V out（j） =U i1（j） +U P1（j） .

[0153] Based on the above technical solutions, optionally, the voltage output to the motor is controlled according to the first target current and the second target current, including:

[0154] Step d1: Multiply the difference between the first target current and the first actual current by the first current proportional coefficient to obtain the first current proportional term of the current speed control cycle.

[0155] For example, the first target current is I d_refThe first actual current is I d_fab The first current proportionality coefficient is K. P2 For example, if the current speed control cycle is the j-th speed control cycle, then the first current proportional term U of the current speed control cycle... P2（j） For U P2（j） =(I d_ref -I d_fab )×K P2 .

[0156] Step d2: Multiply the first current proportional term of the current speed control cycle by the first current integral coefficient, and add the first current integral term of the previous speed control cycle to obtain the first current integral term of the current speed control cycle.

[0157] For example, the first current integral coefficient is K. i2 The first current integral term of the previous speed control cycle is U. i2（j-1） The first current integral term U in the current speed control cycle i2（j） For U i2（j） =U i2（j-1） +K i2 ×U P2（j） .

[0158] Step d3: Take the sum of the first current proportional term and the first current integral term of the current speed control cycle as the first control quantity.

[0159] Specifically, the sum of the first proportional term and the first integral term of the current speed control cycle is used as the first control quantity of the current speed control cycle. For example, if the current speed control cycle is the j-th speed control cycle, then the first control quantity U of the current speed control cycle is... d（j） For U d（j） =U P2（j） +U i2（j） .

[0160] Step d4: Multiply the difference between the second target current and the second actual current by the second current proportional coefficient to obtain the second current proportional term for the current speed control cycle.

[0161] For example, the second target current is I. q_ref The second actual current is I q_fab The second current proportionality coefficient is K. P3 For example, if the current speed control cycle is the j-th speed control cycle, then the second current proportional term U of the current speed control cycle... P3（j） For U P3（j） =(I q_ref -I q_fab )×K P3 .

[0162] Step d5: Multiply the second current proportional term of the current speed control cycle by the second current integral coefficient, and add the second current integral term of the previous speed control cycle to obtain the second current integral term of the current speed control cycle.

[0163] For example, the second current integral coefficient is K. i3 The second current integral term of the previous speed control cycle is U. i3（j-1） The second current integral term U in the current speed control cycle i3（j） For U i3（j） =U i3（j-1） +K i3 ×U P3（j） .

[0164] Step d6: Take the sum of the second current proportional term and the second current integral term of the current speed control cycle as the second control quantity.

[0165] Specifically, the second current proportional term and the second current integral term of the current speed control cycle are added together to obtain the second control quantity of the current speed control cycle. For example, if the current speed control cycle is the j-th speed control cycle, then the second control quantity U of the current speed control cycle is... q（j） For U q（j） =U P3（j） +U i3（j） .

[0166] Step d7: Control the voltage output to the motor according to the first control quantity and the second control quantity.

[0167] Specifically, the first and second control quantities are transformed by coordinate transformation and then subjected to Sine Pulse Width Modulation (SPWM) to obtain a control signal. The control signal is then output to the gate of the transistor in the voltage circuit (e.g., inverter circuit) connected to the motor to control the voltage output of the voltage circuit, i.e., to control the voltage connected to the motor, thereby controlling the operation of the motor and thus controlling the operation of the vehicle.

[0168] Based on the above technical solutions, Figure 3 This is a flowchart of another vehicle control method based on a permanent magnet motor provided in an embodiment of the present invention. Optionally, refer to... Figure 3 Vehicle control methods based on permanent magnet motors include:

[0169] S310. In the current speed control cycle, determine whether the target speed and target torque commands are zero. If yes, proceed to step S320; otherwise, proceed to step S330.

[0170] Specifically, in the current speed control cycle, if the accelerator is released, the target speed and target torque commands of the motor are zero, regardless of whether the vehicle is braking. If the accelerator is not released, the target speed and target torque commands are not zero, and the vehicle accelerates, maintains a constant speed, or decelerates.

[0171] S320: Based on the speed control strategy, the torque output value is determined according to the target speed and the actual speed.

[0172] Specifically, if the target speed and target torque commands are zero, then in the current speed control cycle, the speed command corresponding to the previous speed control cycle is subtracted from the preset deceleration to obtain the speed command for the current speed control cycle. The speed command for the current speed control cycle and the actual speed are input to the speed control strategy. The output value of the speed control strategy is the torque output value. Then, the first target current and the second target current are output according to the torque output value. When the motor voltage is controlled according to the first target current and the second target current, the motor speed can be changed to the speed command of the current speed control cycle. The speed command of the current speed control cycle gradually decreases to the target speed, so that the motor speed is close to or equal to the target speed, that is, the motor speed is close to or equal to zero, so that the vehicle stops, thus realizing the control of the vehicle.

[0173] S330. Determine if the vehicle is braking. If not, proceed to step S340; if yes, proceed to step S350.

[0174] S340. Determine the current torque limit based on the first electric torque limit, the second electric torque limit, and the current torque command.

[0175] S350. Determine the current torque limit based on the first braking torque limit, the second braking torque limit, and the current torque command.

[0176] S360: When the target speed and target torque commands are not zero, based on the speed control strategy, the torque output value is determined according to the preset maximum speed and the actual speed of the motor, with the current torque limit as the limit.

[0177] S370. Determine the first target current and the second target current based on the torque output value, the actual speed and the first preset correspondence; wherein, the first target current is the target current of the d-axis and the second target current is the target current of the q-axis.

[0178] S380: Control the voltage output to the motor according to the first target current and the second target current, and return to execute the next speed control cycle until the motor reaches the target state.

[0179] Based on the above technical solution, optionally, when the target speed and target torque commands are not zero, the motor reaches the target state, including:

[0180] The difference between the actual torque of the motor and the target torque command is less than the first threshold.

[0181] The first threshold is a value close to zero.

[0182] Specifically, when the target speed and target torque commands are not zero, in the current speed control cycle, the torque output value is related to the current torque command, ensuring that after each speed control cycle, the actual torque of the motor is close to or equal to the current torque command. The current torque command periodically changes to the target torque command, so that the actual torque of the motor eventually approaches or equals the target torque command. Therefore, when the target speed and target torque commands are not zero, if the difference between the actual torque of the motor and the target torque command is less than a first threshold, it indicates that the motor has reached the target state.

[0183] Optionally, when the target speed and target torque commands are zero, the motor reaches the target state, including:

[0184] The time during which the absolute value of the motor's actual rotational speed is less than the second threshold reaches the preset time.

[0185] The second threshold is a value close to zero, and the second threshold is greater than zero.

[0186] Specifically, when both the target speed and target torque commands are zero, in each speed control cycle, the speed control strategy targets the speed command of the current speed control cycle and outputs a torque value. The speed command of the current speed control cycle gradually changes towards the target speed of zero, causing the actual speed of the motor to gradually approach or equal the target speed. Therefore, if the target speed is zero, when the absolute value of the motor's actual speed is less than the second threshold for a preset duration, it indicates that the absolute value of the motor's actual speed is stably less than the second threshold, indicating that the actual speed of the motor is close to zero, that is, the motor has reached the target state, and the vehicle stops.

[0187] Based on the above technical solution, optionally, in the current speed control cycle, when the target speed and target torque command are zero, the torque output value is determined according to the target speed and actual speed based on the speed control strategy, including:

[0188] Step e1: If the current speed control cycle is the first speed control cycle after the target speed and target torque commands change from non-zero to zero, then the actual speed of the motor is taken as the current speed command of the current speed control cycle.

[0189] Specifically, in the first speed control cycle after the target speed and target torque commands change from non-zero to zero, the actual speed of the motor is used as the current speed command for the current speed control cycle, so that the deviation between the actual speed of the motor and the current speed command is zero. This avoids the situation where the current speed command changes too much when the target speed and target torque commands change too much, which would lead to an excessive change in the actual speed of the motor and cause vehicle instability.

[0190] Step e2: If the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and target torque commands change from non-zero to zero, then when the absolute value of the current speed command is less than the difference threshold, the difference between the previous speed command of the previous speed control cycle and the preset deceleration is taken as the current speed command of the current speed control cycle.

[0191] The preset deceleration is a positive value.

[0192] Specifically, when the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and target torque commands change from non-zero to zero, in the current speed control cycle, the difference between the previous speed command of the previous speed control cycle and the preset deceleration is used as the current speed command of the current speed control cycle, so that the current speed command changes periodically until the current speed command is close to or equal to zero, that is, the absolute value of the current speed command is less than the difference threshold, so that the actual speed of the motor is close to or equal to zero.

[0193] Step e3: Multiply the difference between the current speed command and the actual speed in the current speed control cycle by the speed proportional coefficient to obtain the speed proportional term for the current speed control cycle.

[0194] Specifically, the difference between the current speed command and the actual speed determines the deviation between the motor's actual speed and the current speed command. Multiplying this deviation by the speed proportionality coefficient yields the speed proportional term for the current speed control cycle. When the current speed control cycle is the first speed control cycle after the target speed and target torque commands have changed from non-zero to zero, the motor's actual speed is the same as the current speed command for the current speed control cycle, and the speed proportional term is zero.

[0195] Step e4: If the current speed control cycle is the first speed control cycle after the target speed and target torque commands change from non-zero to zero, then the output value of the speed control strategy of the previous speed control cycle is used as the speed integral term of the current speed control cycle.

[0196] Specifically, when the current speed control cycle is the first speed control cycle after the target speed and target torque commands change from non-zero to zero, the output value of the speed control strategy of the previous speed control cycle is used as the speed integral term of the current speed control cycle, and the speed proportional term is zero. This ensures that the output value of the speed proportional term corresponding to the current speed control cycle is the same as the output value of the speed control strategy of the previous speed control cycle, thus avoiding sudden changes in the motor voltage.

[0197] Step e5: If the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and target torque commands change from non-zero to zero, then the sum of the product of the speed proportional term of the current speed control cycle and the speed integral coefficient and the speed integral term of the previous speed control cycle is taken as the speed integral term of the current speed control cycle.

[0198] Specifically, by multiplying the speed proportional term of the current speed control cycle by the speed integral coefficient and adding the speed integral term of the previous speed control cycle, the cumulative amount of deviation can be determined, which is the speed integral term of the current speed control cycle.

[0199] Step e6: The sum of the proportional term of the current speed control cycle and the integral term of the current speed control cycle is used as the torque output value.

[0200] Specifically, the sum of the proportional term and integral term of the current speed control cycle is used as the output value of the speed control strategy for the current speed control cycle.

[0201] This invention also provides a vehicle control device based on a permanent magnet motor, which is used to execute the vehicle control method based on a permanent magnet motor provided in any embodiment of this invention. Figure 4 This is a schematic diagram of a vehicle control device based on a permanent magnet motor provided in an embodiment of the present invention. (Refer to...) Figure 4 The vehicle control device based on the permanent magnet motor includes:

[0202] The limit determination module 101 is used to determine the current torque limit based on the actual speed of the motor, the actual operating conditions of the vehicle, and the current torque command during the current speed control cycle when the target speed and target torque command are not zero.

[0203] The torque output value determination module 102 is used to determine the torque output value based on the speed control strategy, with the current torque limit value as a limit, and according to the preset maximum speed and the actual speed of the motor when the target speed and the target torque command are not zero.

[0204] The target current determination module 103 is used to determine a first target current and a second target current based on the torque output value, the actual speed and a first preset correspondence; wherein, the first target current is the target current of the d-axis and the second target current is the target current of the q-axis.

[0205] The control module 104 is used to control the voltage output to the motor according to the first target current and the second target current, and return to execute the next speed control cycle until the motor reaches the target state.

[0206] The vehicle control device based on a permanent magnet motor provided in the embodiments of the present invention can execute the vehicle control method based on a permanent magnet motor provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the method.

[0207] This invention also provides a vehicle that includes a vehicle control device based on a permanent magnet motor provided in any embodiment of this invention. Therefore, the vehicle in this embodiment has the same beneficial effects as the vehicle control device based on a permanent magnet motor provided in any embodiment of this invention, and will not be described again here.

[0208] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0209] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A vehicle control method based on a permanent magnet motor, characterized in that, include: In the current speed control cycle, when the target speed and target torque command are not zero, the current torque limit is determined based on the actual speed of the motor, the actual operating conditions of the vehicle, and the current torque command. When the target speed and target torque commands are not zero, based on the speed control strategy, the torque output value is determined according to the preset maximum speed and the actual speed of the motor, with the current torque limit as the limit; The first target current and the second target current are determined based on the torque output value, the actual speed, and the first preset correspondence; wherein, the first target current is the target current of the d-axis, and the second target current is the target current of the q-axis; The voltage output to the motor is controlled according to the first target current and the second target current, and the process returns to execute the next speed control cycle until the motor reaches the target state. The determination of the current torque limit based on the actual motor speed, the actual operating condition of the vehicle, and the current torque command includes: when the vehicle is not braking, determining the current torque limit based on a first electric torque limit, a second electric torque limit, and the current torque command; wherein the first electric torque limit is the electric torque limit corresponding to the actual motor speed, and the second electric torque limit is the electric torque limit corresponding to the actual operating condition of the vehicle; and when the vehicle is braking, determining the current torque limit based on a first braking torque limit, a second braking torque limit, and the current torque command; wherein the first braking torque limit is the braking torque limit corresponding to the actual speed, and the second braking torque limit is the braking torque limit corresponding to the actual operating condition. The method of determining the torque output value based on the speed control strategy, with the current torque limit as a constraint, according to the preset maximum speed and the actual speed of the motor, includes: determining the output value of the speed control strategy based on the preset maximum speed and the actual speed of the motor; when the absolute value of the output value of the speed control strategy is greater than the absolute value of the current torque limit, setting the current torque limit as the torque output value; and when the absolute value of the output value of the speed control strategy is less than or equal to the absolute value of the current torque limit, setting the output value of the speed control strategy as the torque output value.

2. The method according to claim 1, characterized in that, Before determining the current torque limit based on the actual motor speed, the actual operating conditions of the vehicle, and the current torque command, the method further includes: The preset maximum speed is determined based on the target torque command and the direction of motor speed; The current torque command for the current speed control cycle is determined based on the previous torque command and torque change slope of the previous speed control cycle.

3. The method according to claim 1, characterized in that, The current torque limit is determined based on the first electric torque limit, the second electric torque limit, and the current torque command, including: The minimum value among the first electric torque limit, the second electric torque limit, and the current torque command is taken as the current torque limit; The current torque limit is determined based on the first braking torque limit, the second braking torque limit, and the current torque command, including: The torque value corresponding to the minimum value among the absolute values ​​of the first braking torque limit, the second braking torque limit, and the current torque command is taken as the current torque limit.

4. The method according to claim 1, characterized in that, Before determining the current torque limit based on the first electric torque limit, the second electric torque limit, and the current torque command, the method further includes: The first electric torque limit is determined based on the actual rotational speed and the second preset correspondence; wherein, the second preset correspondence is the correspondence between the actual rotational speed and the first electric torque limit. The second electric torque limit is determined based on the actual operating conditions and the third preset correspondence; wherein, the third preset correspondence is the correspondence between the actual operating conditions and the second electric torque limit. Before determining the current torque limit based on the first braking torque limit, the second braking torque limit, and the current torque command, the method further includes: The first braking torque limit is determined based on the actual rotational speed and the fourth preset correspondence; wherein, the fourth preset correspondence is the correspondence between the actual rotational speed and the first braking torque limit. The second braking torque limit is determined based on the actual operating conditions and the fifth preset correspondence; wherein, the fifth preset correspondence is the correspondence between the actual operating conditions and the second braking torque limit.

5. The method according to claim 1, characterized in that, Based on the speed control strategy, the output value of the speed control strategy is determined according to the preset maximum speed and the actual speed of the motor, including: If the current speed control cycle is the first speed control cycle after the target speed and the target torque command change from zero to non-zero, then the actual speed of the motor is taken as the current speed command of the current speed control cycle; If the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and the target torque command change from zero to non-zero, then when the difference between the absolute value of the current speed command and the absolute value of the preset maximum speed is less than the difference threshold, the sum of the previous speed command of the previous speed control cycle and the preset acceleration is taken as the current speed command of the current speed control cycle. The difference between the current speed command and the actual speed in the current speed control cycle is multiplied by the speed proportional coefficient to obtain the speed proportional term for the current speed control cycle. If the current speed control cycle is the first speed control cycle after the target speed and the target torque command change from zero to non-zero, then the output value of the speed control strategy of the previous speed control cycle is used as the speed integral term of the current speed control cycle. If the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and the target torque command change from zero to non-zero, then the product of the speed proportional term of the current speed control cycle and the speed integral coefficient, and the sum of the speed integral term of the previous speed control cycle, are used as the speed integral term of the current speed control cycle. The sum of the proportional term of the current speed control cycle and the integral term of the current speed control cycle is used as the output value of the speed control strategy.

6. The method according to any one of claims 1-5, characterized in that, Controlling the voltage output to the motor based on the first target current and the second target current includes: The difference between the first target current and the first actual current is multiplied by the first current proportional coefficient to obtain the first current proportional term of the current speed control cycle. Multiply the first current proportional term of the current speed control cycle by the first current integral coefficient, and add the first current integral term of the previous speed control cycle to obtain the first current integral term of the current speed control cycle. The sum of the first current proportional term and the first current integral term of the current speed control cycle is used as the first control quantity; The difference between the second target current and the second actual current is multiplied by the second current proportional coefficient to obtain the second current proportional term for the current speed control cycle. Multiply the second current proportional term of the current speed control cycle by the second current integral coefficient, and add the second current integral term of the previous speed control cycle to obtain the second current integral term of the current speed control cycle. The sum of the second current proportional term and the second current integral term of the current speed control cycle is used as the second control quantity; The voltage output to the motor is controlled according to the first control quantity and the second control quantity.

7. The method according to any one of claims 1-5, characterized in that, Before determining the first target current and the second target current based on the torque output value, the actual rotational speed, and the first preset correspondence, the method further includes: In the current speed control cycle, when the target speed and target torque command are both zero, the torque output value is determined based on the speed control strategy, according to the target speed and the actual speed. When the target speed and target torque commands are not zero, the motor reaches the target state, including: The difference between the actual torque of the motor and the target torque command is less than a first threshold. When the target speed and target torque commands are zero, the motor reaches the target state, including: The absolute value of the actual rotational speed of the motor is less than the second threshold for a preset duration.

8. The method according to claim 7, characterized in that, In the current speed control cycle, when both the target speed and target torque command are zero, based on the speed control strategy, the torque output value is determined according to the target speed and the actual speed, including: If the current speed control cycle is the first speed control cycle after the target speed and the target torque command change from non-zero to zero, then the actual speed of the motor is taken as the current speed command of the current speed control cycle; If the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and the target torque command change from non-zero to zero, then when the absolute value of the current speed command is less than the difference threshold, the difference between the previous speed command of the previous speed control cycle and the preset deceleration is taken as the current speed command of the current speed control cycle. The difference between the current speed command and the actual speed in the current speed control cycle is multiplied by the speed proportional coefficient to obtain the speed proportional term for the current speed control cycle. If the current speed control cycle is the first speed control cycle after the target speed and the target torque command change from non-zero to zero, then the output value of the speed control strategy of the previous speed control cycle is used as the speed integral term of the current speed control cycle. If the current speed control cycle is a speed control cycle other than the first speed control cycle after the target speed and the target torque command change from non-zero to zero, then the product of the speed proportional term of the current speed control cycle and the speed integral coefficient, and the sum of the speed integral term of the previous speed control cycle, are used as the speed integral term of the current speed control cycle. The sum of the proportional term of the current speed control cycle and the integral term of the current speed control cycle is used as the torque output value.

9. A vehicle control device based on a permanent magnet motor, used to execute the vehicle control method based on a permanent magnet motor as described in any one of claims 1-8, characterized in that, include: The limit determination module is used to determine the current torque limit based on the actual motor speed, the actual operating conditions of the vehicle, and the current torque command during the current speed control cycle, when the target speed and target torque commands are not zero. The torque output value determination module is used to determine the torque output value based on the speed control strategy, with the current torque limit value as a limit, and according to the preset maximum speed and the actual speed of the motor when the target speed and the target torque command are not zero. The target current determination module is used to determine a first target current and a second target current based on the torque output value, the actual speed, and a first preset correspondence; wherein, the first target current is the target current of the d-axis, and the second target current is the target current of the q-axis; The control module is used to control the voltage output to the motor according to the first target current and the second target current, and return to execute the next speed control cycle until the motor reaches the target state.

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