Permanent magnet synchronous motor control method and device, controller and storage medium

Abstract

The application relates to a permanent magnet synchronous motor control method and device, a controller and a storage medium. The method comprises the following steps: obtaining the motor speed of a to-be-controlled permanent magnet synchronous motor, the target torque of the permanent magnet synchronous motor and the speed threshold of the permanent magnet synchronous motor; the rotor of the permanent magnet synchronous motor comprises permanent magnets and an electric excitation winding; in the case that the motor speed is less than the speed threshold, the excitation current input to the electric excitation winding is obtained according to the target torque; in the case that the motor speed is greater than or equal to the speed threshold, the maximum allowable counter electromotive force of the permanent magnet synchronous motor is obtained, and the excitation current input to the electric excitation winding is obtained according to the maximum allowable counter electromotive force; and the input current of the permanent magnet synchronous motor is controlled based on the excitation current. According to the method, the input current of the electric excitation winding added in the rotor can be controlled according to the motor speed, the magnetic field of the permanent magnet synchronous motor is adjusted, the effects of low-speed magnetic field enhancement and high-speed magnetic field weakening are realized, and the motor control efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of automotive technology, and in particular to a method, apparatus, controller, and storage medium for controlling a permanent magnet synchronous motor. Background Technology

[0002] With the development of automotive technology, a technology has emerged that integrates permanent magnet synchronous motors into automobiles. These permanent magnet synchronous motors are currently the mainstream drive motor type for new energy vehicles, and are widely used in the drive systems of electric vehicles due to their high efficiency, high power density, and excellent control performance.

[0003] In traditional technology, permanent magnet synchronous motors typically use rare-earth permanent magnets to provide a constant magnetic field. However, this approach has several drawbacks. At high speeds, the back electromotive force (EMF) of the motor increases with speed. To maintain voltage balance, a weak magnetic component must be injected into the stator current to counteract the rotor magnetic field. This leads to a significant increase in copper and iron losses and a substantial decrease in motor efficiency. Furthermore, the constant permanent magnet magnetic field limits the upper limit of the back EMF, restricting the maximum motor speed to the battery voltage and making it difficult to further expand the speed range. Additionally, the rotor magnetic field is not adjustable under all operating conditions. At low speeds and high loads, the magnetic field is insufficient, while at high speeds and with weak magnetic field, it is excessive, making it impossible to achieve optimal energy consumption matching across the entire speed range.

[0004] Therefore, there is an urgent need for a control method for permanent magnet synchronous motors with adjustable magnetic fields to solve the above-mentioned defects caused by constant magnetic fields. Summary of the Invention

[0005] Based on this, this application addresses the aforementioned technical problems by providing a method, apparatus, controller, computer-readable storage medium, and computer program product for controlling a permanent magnet synchronous motor capable of adjusting the magnetic field of the permanent magnet synchronous motor.

[0006] In a first aspect, this application provides a method for controlling a permanent magnet synchronous motor, including:

[0007] The motor speed of the permanent magnet synchronous motor to be controlled, the target torque of the permanent magnet synchronous motor, and the speed threshold of the permanent magnet synchronous motor are obtained; the rotor of the permanent magnet synchronous motor includes a permanent magnet and an electrically excited winding; the motor speed is compared with the speed threshold.

[0008] When the motor speed is less than the speed threshold, the excitation current input to the electric excitation winding is obtained according to the target torque;

[0009] When the motor speed is greater than or equal to the speed threshold, the maximum allowable back electromotive force of the permanent magnet synchronous motor is obtained, and the excitation current input to the electric excitation winding is obtained based on the maximum allowable back electromotive force.

[0010] The input current of the permanent magnet synchronous motor is controlled based on the excitation current.

[0011] In one embodiment, when the motor speed is less than the speed threshold, the excitation current is calculated through the following steps: obtaining the basic magnetic field strength provided by the permanent magnet; obtaining the target rotor magnetic field strength according to the target torque; and obtaining the excitation current according to the difference between the target rotor magnetic field strength and the basic magnetic field strength, and the excitation coefficient of the electrically excited winding.

[0012] In one embodiment, when the motor speed is greater than or equal to the speed threshold, the excitation current is calculated through the following steps: obtaining a pre-set back electromotive force constant and the basic magnetic field strength provided by the permanent magnet; obtaining the target rotor magnetic field strength based on the maximum allowable back electromotive force, the back electromotive force constant, and the motor speed; and obtaining the excitation current based on the difference between the target rotor magnetic field strength and the basic magnetic field strength, and the excitation coefficient of the electrically excited winding.

[0013] In one embodiment, obtaining the maximum permissible back electromotive force of the permanent magnet synchronous motor includes: obtaining the DC bus voltage of the permanent magnet synchronous motor; and obtaining the maximum permissible back electromotive force based on the DC bus voltage and a preset back electromotive force safety factor.

[0014] In one embodiment, the method further includes:

[0015] Based on the excitation current, the first flux linkage corresponding to the electrically excited winding is obtained, and based on the first flux linkage and the second flux linkage corresponding to the permanent magnet, the rotor flux linkage corresponding to the rotor is obtained; based on the rotor flux linkage and the target torque, the quadrature-axis component of the stator current input to the permanent magnet synchronous motor is obtained, and the direct-axis component of the stator current is set to zero; the control of the input current of the permanent magnet synchronous motor based on the excitation current includes: controlling the input current of the permanent magnet synchronous motor based on the excitation current, the quadrature-axis component and the direct-axis component of the stator current.

[0016] In one embodiment, controlling the input current of the permanent magnet synchronous motor based on the excitation current includes: obtaining a preset maximum value of the excitation current; controlling the input current of the permanent magnet synchronous motor based on the excitation current when the current value of the excitation current is less than or equal to the maximum value of the excitation current; and adjusting the current value of the excitation current to the maximum value of the excitation current when the current value of the excitation current is greater than the maximum value of the excitation current, and controlling the input current of the permanent magnet synchronous motor based on the adjusted excitation current.

[0017] In one embodiment, the speed threshold of the permanent magnet synchronous motor is obtained through the following steps: obtaining the DC bus voltage of the permanent magnet synchronous motor, the pre-set back electromotive force constant, and the basic magnetic field strength provided by the permanent magnet; and obtaining the speed threshold based on the DC bus voltage, the back electromotive force constant, and the basic magnetic field strength.

[0018] Secondly, this application also provides a permanent magnet synchronous motor control device, comprising:

[0019] The motor data acquisition module is used to acquire the motor speed of the permanent magnet synchronous motor to be controlled, the target torque of the permanent magnet synchronous motor, and the speed threshold of the permanent magnet synchronous motor; the rotor of the permanent magnet synchronous motor includes a permanent magnet and an electrically excited winding; the motor speed is compared with the speed threshold.

[0020] The first excitation current acquisition module is used to acquire the excitation current input to the electric excitation winding based on the target torque when the motor speed is less than the speed threshold.

[0021] The second excitation current acquisition module is used to acquire the maximum allowable back electromotive force of the permanent magnet synchronous motor when the motor speed is greater than or equal to the speed threshold, and to acquire the excitation current input to the electric excitation winding based on the maximum allowable back electromotive force.

[0022] The permanent magnet motor control module is used to control the input current of the permanent magnet synchronous motor based on the excitation current.

[0023] Thirdly, this application also provides a controller, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the methods described above.

[0024] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described above.

[0025] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the method described in any of the above aspects.

[0026] The aforementioned permanent magnet synchronous motor control method, device, controller, and storage medium acquire the motor speed, target torque, and speed threshold of the permanent magnet synchronous motor to be controlled; the rotor of the permanent magnet synchronous motor includes a permanent magnet and an electrically excited winding; when the motor speed is less than the speed threshold, the excitation current of the input electrically excited winding is acquired based on the target torque; when the motor speed is greater than or equal to the speed threshold, the maximum permissible back electromotive force of the permanent magnet synchronous motor is acquired, and the excitation current of the input electrically excited winding is acquired based on the maximum permissible back electromotive force; the input current of the permanent magnet synchronous motor is controlled based on the excitation current. The rotor of the permanent magnet synchronous motor of this application may include a permanent magnet and an electrically excited winding. By collecting the motor speed, target torque, and speed threshold of the permanent magnet synchronous motor, if the motor speed is less than the speed threshold, the excitation current of the input electrically excited winding is obtained based on the target torque to achieve low-speed magnetization. If the motor speed is greater than or equal to the speed threshold, the excitation current of the input electrically excited winding is obtained based on the maximum allowable back electromotive force to achieve high-speed field weakening. Thus, the input current of the electrically excited winding of the permanent magnet synchronous motor is controlled based on the excitation current. In this way, the input current of the electrically excited winding added to the rotor can be controlled according to the motor speed to adjust the magnetic field of the permanent magnet synchronous motor and achieve the effects of low-speed magnetization and high-speed field weakening. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic flowchart of an optional permanent magnet synchronous motor control method in one embodiment;

[0029] Figure 2 This is a schematic diagram of an optional process for obtaining the excitation current in one embodiment;

[0030] Figure 3 This is a schematic diagram of an optional process for obtaining the excitation current in another embodiment;

[0031] Figure 4 This is a schematic diagram of an optional flow of a permanent magnet synchronous motor control method in another embodiment;

[0032] Figure 5 This is a schematic diagram of an optional structure of a permanent magnet synchronous motor control device in one embodiment;

[0033] Figure 6This is a schematic diagram of an optional internal structure of the controller in one embodiment. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0035] The terms "first," "second," etc., used in this application may be used to describe various elements, but these elements are not limited by these terms. These terms are used only to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the embodiments, or any combination of multiple embodiments.

[0036] In one embodiment, such as Figure 1 As shown, a control method for a permanent magnet synchronous motor is provided. Taking the application of this method to a controller of a permanent magnet synchronous motor as an example, the method includes the following steps:

[0037] Step S101: Obtain the motor speed, target torque, and speed threshold of the permanent magnet synchronous motor to be controlled; the rotor of the permanent magnet synchronous motor includes permanent magnets and electrically excited windings; compare the motor speed with the speed threshold.

[0038] The permanent magnet synchronous motor to be controlled refers to a permanent magnet synchronous motor that requires magnetic field control. This motor may include a stator and a rotor, with the rotor consisting of permanent magnets and electrically excited windings. The permanent magnets provide the basic excitation magnetic field, while the electrically excited windings generate an auxiliary magnetic field in the same or opposite direction as the permanent magnets by being energized, thereby achieving magnetic field regulation. The target torque of the permanent magnet synchronous motor refers to its torque output target, while the speed threshold is used to determine whether the motor speed is too high or too low; this threshold can be preset.

[0039] Specifically, when controlling a permanent magnet synchronous motor, the real-time speed (motor speed), torque output target (target torque), and speed threshold of the permanent magnet synchronous motor to be controlled can be collected first. Then, the motor speed can be compared with the speed threshold of the permanent magnet synchronous motor.

[0040] Step S102: When the motor speed is less than the speed threshold, obtain the excitation current of the input electric excitation winding according to the target torque.

[0041] Excitation current refers to the input current to the electric excitation winding. In this embodiment, if the motor speed is less than the speed threshold, that is, when the motor is in low-speed mode, the excitation current input to the electric excitation winding can be calculated based on the target torque. This excitation current can be a positive value to provide a positive magnetizing magnetic field, thereby achieving low-speed magnetization.

[0042] Step S103: When the motor speed is greater than or equal to the speed threshold, obtain the maximum allowable back EMF of the permanent magnet synchronous motor, and obtain the excitation current of the input excitation winding based on the maximum allowable back EMF.

[0043] The maximum permissible back EMF refers to the maximum back EMF value that the stator winding of the motor can withstand and that the inverter can safely match under rated operating conditions and within the design allowable range. If the motor speed is greater than or equal to the speed threshold, the controller can calculate the excitation current of the input excitation winding based on the maximum permissible back EMF. Compared to the current excitation current of the input excitation winding, this excitation current can be a relatively small positive value or a negative value, used to reduce the currently provided positive magnetic field or even provide a reverse magnetic field to weaken the rotor magnetic field.

[0044] Step S104: Control the input current of the permanent magnet synchronous motor based on the excitation current.

[0045] After obtaining the excitation current through step S102 or step S103, the controller can control the input current of the permanent magnet synchronous motor based on the excitation current. For example, the excitation current can be used as the control target, and the input current of the electric excitation winding of the permanent magnet synchronous motor can be controlled by PI control (proportional integral control).

[0046] In the aforementioned permanent magnet synchronous motor control method, the motor speed, target torque, and speed threshold of the permanent magnet synchronous motor to be controlled are obtained. The rotor of the permanent magnet synchronous motor includes a permanent magnet and an electrically excited winding. When the motor speed is less than the speed threshold, the excitation current of the input electrically excited winding is obtained based on the target torque. When the motor speed is greater than or equal to the speed threshold, the maximum allowable back electromotive force of the permanent magnet synchronous motor is obtained, and the excitation current of the input electrically excited winding is obtained based on the maximum allowable back electromotive force. The input current of the permanent magnet synchronous motor is controlled based on the excitation current. The rotor of the permanent magnet synchronous motor of this application may include a permanent magnet and an electrically excited winding. By collecting the motor speed, target torque, and speed threshold of the permanent magnet synchronous motor, if the motor speed is less than the speed threshold, the excitation current of the input electrically excited winding is obtained based on the target torque to achieve low-speed magnetization. If the motor speed is greater than or equal to the speed threshold, the excitation current of the input electrically excited winding is obtained based on the maximum allowable back electromotive force to achieve high-speed field weakening. Thus, the input current of the electrically excited winding of the permanent magnet synchronous motor is controlled based on the excitation current. In this way, the input current of the electrically excited winding added to the rotor can be controlled according to the motor speed to adjust the magnetic field of the permanent magnet synchronous motor and achieve the effects of low-speed magnetization and high-speed field weakening.

[0047] In one embodiment, such as Figure 2 As shown, step S102 may further include:

[0048] Step S201: Obtain the basic magnetic field strength provided by the permanent magnet;

[0049] Step S202: Obtain the target rotor magnetic field strength based on the target torque.

[0050] The target rotor magnetic field strength refers to the required magnetic field strength of the rotor to output the target torque, while the base magnetic field strength refers to the magnetic field strength provided by the permanent magnets in the rotor. Specifically, the controller can first determine the target torque... The magnetic field strength of the target rotor was calculated. At the same time, it can also obtain the basic magnetic field strength provided by the permanent magnet. .

[0051] Step S203: Obtain the excitation current based on the difference between the target rotor magnetic field strength and the foundation magnetic field strength, and the excitation coefficient of the electrically excited winding.

[0052] The difference between the target rotor magnetic field strength and the base magnetic field strength can be used to characterize the magnetic field strength provided by the electric excitation winding. After obtaining the target rotor magnetic field strength and the base magnetic field strength, the difference between the target rotor magnetic field strength and the base magnetic field strength can also be calculated. Then, by combining this difference with the excitation coefficient of the electric excitation winding, the excitation current can be calculated.

[0053] For example, the target rotor magnetic field strength It can be represented by the following formula:

[0054]

[0055] Therefore, in obtaining the target rotor magnetic field strength Basic magnetic field strength and excitation coefficient Then, the forward excitation current can be calculated using the following formula:

[0056]

[0057] in, Indicates the magnetic field strength of the target rotor. Indicates the basic magnetic field strength. This represents the excitation coefficient, which is the conversion coefficient between the positive excitation magnetic field strength and the positive excitation current. This indicates the positive excitation current.

[0058] In this embodiment, when the motor speed is less than the speed threshold, the excitation current can be obtained by combining the magnetic field strength required by the target rotor calculated from the target torque and the basic magnetic field strength provided by the permanent magnet. This method can improve the accuracy of the forward excitation current calculation.

[0059] In one embodiment, such as Figure 3 As shown, step S103 may further include:

[0060] Step S301: Obtain the pre-set back electromotive force constant and the basic magnetic field strength provided by the permanent magnet.

[0061] back electromotive force constant This can be understood as the magnitude of the back electromotive force generated by the motor at a unit speed, describing the ability of the rotor magnetic field to cut the stator windings and generate back electromotive force. In this embodiment, when the motor speed is greater than or equal to the speed threshold, a pre-set back electromotive force constant and the basic magnetic field strength provided by the permanent magnet can be obtained first. .

[0062] Step S302: Obtain the target rotor magnetic field strength based on the maximum allowable back EMF, the back EMF constant, and the motor speed.

[0063] Then, by combining the maximum permissible back EMF, the back EMF constant, and the motor speed, the required output magnetic field strength of the rotor, i.e., the target rotor magnetic field strength, can be calculated. This target rotor magnetic field strength can be calculated using the following formula:

[0064]

[0065] in, Indicates the magnetic field strength of the target rotor. Indicates the maximum permissible back electromotive force. Represents the back electromotive force constant. This indicates the current real-time motor speed.

[0066] Step S303: Obtain the excitation current based on the difference between the target rotor magnetic field strength and the base magnetic field strength, and the excitation coefficient of the electric excitation winding.

[0067] Finally, the excitation current can be calculated by combining the difference between the target rotor magnetic field strength and the base magnetic field strength, as well as the excitation coefficient of the electrically excited winding. This excitation current can be negative, representing negative regulation. For example, it can be calculated using the following formula:

[0068]

[0069] in, Indicates the magnetic field strength of the target rotor. Indicates the basic magnetic field strength. This represents the excitation coefficient, while This indicates the excitation current.

[0070] In this embodiment, when the motor speed is greater than or equal to the speed threshold, the excitation current can be obtained by combining the magnetic field strength required by the target rotor calculated by the maximum allowable back electromotive force and the basic magnetic field strength provided by the magnet. This method can improve the accuracy of the excitation current calculation.

[0071] In one embodiment, step S301 may further include: obtaining the DC bus voltage of the permanent magnet synchronous motor; and obtaining the maximum permissible back electromotive force based on the DC bus voltage and a preset back electromotive force safety factor.

[0072] The DC bus voltage refers to the DC bus voltage of the permanent magnet synchronous motor driver, while the back EMF safety factor is a pre-set safety factor to ensure the normal operation of the permanent magnet synchronous motor. This factor can be set to 0.95. In this embodiment, the maximum permissible back EMF can be calculated based on the DC bus voltage of the permanent magnet synchronous motor and the pre-set back EMF safety factor. For example, when the back EMF safety factor is 0.95, the maximum permissible back EMF can be calculated using the following formula:

[0073]

[0074] in, Indicates the maximum permissible back electromotive force. This indicates the DC bus voltage.

[0075] In this embodiment, the maximum allowable back EMF can also be calculated by combining a preset back EMF safety factor and the DC bus voltage of the permanent magnet synchronous motor. This method can improve the accuracy of the maximum allowable back EMF calculation.

[0076] In one embodiment, the permanent magnet synchronous motor control method may further include: obtaining a first magnetic flux corresponding to the electrically excited winding based on the excitation current, and obtaining a rotor magnetic flux corresponding to the rotor based on the first magnetic flux and a second magnetic flux corresponding to the permanent magnet; obtaining the quadrature-axis component of the stator current input to the permanent magnet synchronous motor based on the rotor magnetic flux and the target torque, and setting the direct-axis component of the stator current to zero; step S104 may further include: controlling the input current of the permanent magnet synchronous motor based on the excitation current, the quadrature-axis component and the direct-axis component of the stator current.

[0077] In this embodiment, in addition to controlling the excitation current of the input electric excitation winding in the rotor of the permanent magnet synchronous motor, the stator current in the input permanent magnet synchronous motor stator can also be controlled. This stator current may contain two components, namely a quadrature axis component. With direct axis component The cross-axis component Primarily used to generate torque, while the direct-axis component... It is mainly used to regulate magnetic fields.

[0078] Specifically, after obtaining the excitation current through step S102 or step S103, the magnetic flux corresponding to the electrically excited winding, i.e., the first magnetic flux, can be calculated based on the excitation current. At the same time, it can also obtain the second magnetic flux generated by the permanent magnet. This allows us to combine the first and second magnetic flux linkages to obtain the rotor flux linkage corresponding to the rotor. For example, the first magnetic flux linkage can be... With the second magnetic flux The sum of these two values ​​serves as the rotor flux linkage.

[0079] Then, the quadrature-axis component of the stator current can be calculated based on the rotor flux linkage and the target torque. At the same time, the direct-axis component of the stator current can be... Setting it to zero allows all stator current to be used for torque output.

[0080] For example, cross-axis components It can be calculated using the following formula:

[0081]

[0082] in, Indicates the target torque. This indicates the number of pole pairs in a permanent magnet synchronous motor. This indicates the first magnetic linkage, while This indicates the second magnetic link.

[0083] After obtaining the quadrature-axis and direct-axis components of the stator current, the input current of the permanent magnet synchronous motor can be controlled using the excitation current and the quadrature-axis and direct-axis components of the stator current. That is, the input current of the electric excitation winding can be controlled using the excitation current, and the stator current input to the stator can be distributed using the quadrature-axis and direct-axis components.

[0084] In this embodiment, the rotor flux linkage can be calculated based on the excitation current. By combining the rotor flux linkage and the target torque, the quadrature-axis component of the stator current can be obtained, while the direct-axis component is set to zero. This method allows all the stator current to be used for torque output, thus eliminating the need for a field-weakening current to be supplied to the stator, thereby reducing copper loss and energy consumption. Furthermore, the input current control of the permanent magnet synchronous motor can be completed using the excitation current and the quadrature-axis and direct-axis components of the stator current. This method can further improve the control accuracy of the permanent magnet synchronous motor.

[0085] In one embodiment, step S104 may further include: obtaining a preset maximum excitation current value; controlling the input current of the permanent magnet synchronous motor based on the excitation current when the current value of the excitation current is less than or equal to the maximum excitation current value; and adjusting the current value of the excitation current to the maximum excitation current value when the current value of the excitation current is greater than the maximum excitation current value, and controlling the input current of the permanent magnet synchronous motor based on the adjusted excitation current.

[0086] The maximum excitation current refers to the maximum current that can be input to the electric excitation winding. Since the current input to the electric excitation winding will cause the temperature of the electric excitation winding to change, if the input current value is too large, it may cause the temperature of the electric excitation winding to be too high, thereby damaging the electric excitation winding. Therefore, in this embodiment, the maximum excitation current can also be preset to ensure the safety of the permanent magnet synchronous motor.

[0087] Specifically, if the excitation current is less than or equal to the maximum excitation current (i.e., the excitation current does not exceed the maximum excitation current), the controller can directly control the input current of the permanent magnet synchronous motor based on the excitation current. However, if the excitation current is greater than the maximum excitation current (i.e., the excitation current exceeds the maximum excitation current), the controller can adjust the excitation current to the maximum excitation current without changing its direction, and then control the input current of the permanent magnet synchronous motor based on the adjusted excitation current.

[0088] In this embodiment, the maximum excitation current can also be preset. When the output excitation current exceeds the maximum excitation current, the current value of the excitation current can be adjusted to the maximum excitation current. This method can avoid the electric excitation winding temperature from getting too high, thereby damaging the electric excitation winding and improving the safety of the permanent magnet synchronous motor.

[0089] In one embodiment, step S101 may further include: obtaining the DC bus voltage of the permanent magnet synchronous motor, the pre-set back electromotive force constant, and the basic magnetic field strength provided by the permanent magnet; and obtaining the speed threshold based on the DC bus voltage, the back electromotive force constant, and the basic magnetic field strength.

[0090] In this embodiment, the speed threshold can also be calculated based on the DC bus voltage of the permanent magnet synchronous motor, the preset back electromotive force constant, and the basic magnetic field strength provided by the permanent magnet. This speed threshold characterizes the speed when the motor's back electromotive force equals the DC bus voltage. For example, the speed threshold can be calculated using the following formula. :

[0091]

[0092] in, Indicates the speed threshold. Indicates DC bus voltage, Represents the back electromotive force constant. This indicates the strength of the basic magnetic field.

[0093] In this embodiment, the speed threshold can be calculated based on the DC bus voltage of the permanent magnet synchronous motor, the pre-set back electromotive force constant, and the basic magnetic field strength provided by the permanent magnet. This speed threshold can characterize the speed when the motor back electromotive force is equal to the DC bus voltage. This method can improve the accuracy of obtaining the speed threshold.

[0094] In one embodiment, a composite excitation permanent magnet synchronous motor for vehicles and its control method are also provided. By integrating permanent magnets and electric excitation windings in the rotor, the rotor magnetic field can be dynamically adjusted, strengthening the magnetic field at low speeds and weakening the magnetic field at high speeds, thereby avoiding strong and weak magnetic currents under high-speed conditions, achieving the effect of reducing motor energy consumption and expanding the speed regulation range.

[0095] This composite-excitation permanent magnet synchronous motor for automobiles mainly consists of a stator and a rotor, where the rotor can adopt a composite excitation structure of permanent magnets and electrically excited windings. The main working principle is as follows:

[0096] Under low-speed, high-load conditions, a positive current is passed through the electrically excited winding, generating an auxiliary magnetic field in the same direction as the permanent magnet. This magnetic field, when superimposed, enhances the total magnetic field of the rotor, increasing the low-speed output torque and meeting the power requirements of vehicle starting, climbing, and other operating conditions.

[0097] Under high-speed, weak magnetic field conditions, reducing the current in the electric excitation winding (or even introducing a reverse weak current) directly weakens the total magnetic field of the rotor, causing the back electromotive force of the motor to be actively suppressed as the speed increases. This eliminates the need to inject strong and weak magnetic components through the stator current to overcome the back electromotive force, thereby significantly reducing copper and iron losses.

[0098] The core of the control logic is to adjust the magnitude and direction of the electric excitation current in real time based on signals such as motor speed, load torque, and DC bus voltage, so as to achieve the optimal matching between the rotor magnetic field and the operating conditions.

[0099] Specific control methods are as follows: Figure 4 As shown, the control logic consists of the following core steps:

[0100] Operating condition data acquisition: Real-time acquisition of motor speed DC bus voltage Target torque Wait for the signal.

[0101] Magnetic field requirement calculation:

[0102] low speed range ( ): Based on the target torque Calculate the required rotor magnetic field strength Determine the positive excitation current. .

[0103] High-speed section ( Based on bus voltage limits and target speed Calculate the maximum allowable back electromotive force. The required rotor magnetic field strength is calculated in reverse. Determine the electromagnetic current (Can be reduced to 0 or a negative value).

[0104] Current distribution:

[0105] Stator current: Only the torque component needs to be provided. No or only a very small weak magnetic component is required. .

[0106] Rotor electromagnetic current: according to Output control signals to adjust the magnitude and direction of the current in the electric excitation winding.

[0107] Closed-loop regulation: The rotor magnetic field strength is fed back in real time through the back EMF observer or flux observer, and the electric excitation current is corrected to achieve stable control.

[0108] The specific process is as follows:

[0109] 1. Operating condition data acquisition and threshold judgment: Real-time acquisition of motor speed. Target torque DC bus voltage And calculate the base velocity threshold. ;like Enter low-speed magnetization mode; if It enters high-speed weak magnetic field mode.

[0110] 2. Low-speed magnetization mode control:

[0111] (1) Based on the target torque Calculate the required rotor magnetic field and according to A positive magnetizing current is obtained. .

[0112] (2) Distribute the stator current so that , All stator current is used for torque output.

[0113] 3. High-speed field weakening mode control:

[0114] (1) Calculate the maximum allowable back electromotive force Derive the target rotor magnetic field The electromagnetic current is obtained. (Can be adjusted negatively);

[0115] (2) Minimize stator field weakening current Only the torque component is retained. This reduces copper and iron consumption.

[0116] 4. Closed-loop protection: The rotor flux is fed back in real time through the flux monitoring device, and the PI regulator adjusts the electric excitation current; when the temperature of the electric excitation winding exceeds the threshold, the maximum excitation current is linearly limited to prevent overheating damage.

[0117] The aforementioned composite excitation permanent magnet synchronous motor for vehicles and its control method can actively weaken the rotor magnetic field under high-speed conditions, avoid large-current field weakening, thereby reducing copper and iron losses and significantly improving efficiency under high-speed conditions. At the same time, the rotor magnetic field is adjustable, breaking through the limitation of back EMF on the maximum speed, thereby improving the speed regulation ratio. Furthermore, the electric excitation current can be dynamically adjusted, so low-speed magnetization can increase torque and high-speed field weakening can reduce losses, achieving optimal energy consumption matching across the entire speed range.

[0118] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0119] Based on the same inventive concept, this application also provides a permanent magnet synchronous motor control device for implementing the aforementioned permanent magnet synchronous motor control method. The solution provided by this device is similar to the implementation described in the above method; therefore, the specific limitations in one or more embodiments of the permanent magnet synchronous motor control device provided below can be found in the limitations of the permanent magnet synchronous motor control method described above, and will not be repeated here.

[0120] In one embodiment, such as Figure 5 As shown, a permanent magnet synchronous motor control device is provided, including: a motor data acquisition module 501, a first excitation current acquisition module 502, a second excitation current acquisition module 503, and a permanent magnet motor control module 504, wherein:

[0121] The motor data acquisition module 501 is used to acquire the motor speed, the target torque of the permanent magnet synchronous motor, and the speed threshold of the permanent magnet synchronous motor to be controlled; the rotor of the permanent magnet synchronous motor includes a permanent magnet and an electrically excited winding; and compares the motor speed with the speed threshold.

[0122] The first excitation current acquisition module 502 is used to acquire the excitation current of the input electric excitation winding based on the target torque when the motor speed is less than the speed threshold.

[0123] The second excitation current acquisition module 503 is used to acquire the maximum allowable back electromotive force of the permanent magnet synchronous motor when the motor speed is greater than or equal to the speed threshold, and to acquire the excitation current of the input electric excitation winding based on the maximum allowable back electromotive force.

[0124] The permanent magnet motor control module 504 is used to control the input current of the permanent magnet synchronous motor based on the excitation current.

[0125] In one embodiment, the first excitation current acquisition module 502 is further used to acquire the basic magnetic field strength provided by the permanent magnet; acquire the target rotor magnetic field strength according to the target torque; and obtain the excitation current according to the difference between the target rotor magnetic field strength and the basic magnetic field strength, and the excitation coefficient of the electric excitation winding.

[0126] In one embodiment, the second excitation current acquisition module 503 is further used to acquire a pre-set back electromotive force constant and the basic magnetic field strength provided by the permanent magnet; acquire the target rotor magnetic field strength according to the maximum allowable back electromotive force, the back electromotive force constant and the motor speed; and obtain the excitation current according to the difference between the target rotor magnetic field strength and the basic magnetic field strength and the excitation coefficient of the electric excitation winding.

[0127] In one embodiment, the second excitation current acquisition module 503 is further used to acquire the DC bus voltage of the permanent magnet synchronous motor; and to obtain the maximum allowable back electromotive force based on the DC bus voltage and the preset back electromotive force safety factor.

[0128] In one embodiment, the permanent magnet motor control module 504 is further configured to: obtain the first flux linkage corresponding to the electrically excited winding based on the excitation current; obtain the rotor flux linkage corresponding to the rotor based on the first flux linkage and the second flux linkage corresponding to the permanent magnet; obtain the quadrature-axis component of the stator current input to the permanent magnet synchronous motor based on the rotor flux linkage and the target torque; and set the direct-axis component of the stator current to zero; and control the input current of the permanent magnet synchronous motor based on the excitation current, the quadrature-axis component and the direct-axis component of the stator current.

[0129] In one embodiment, the permanent magnet motor control module 504 is further configured to obtain a preset maximum excitation current value; when the excitation current value is less than or equal to the maximum excitation current value, control the input current of the permanent magnet synchronous motor based on the excitation current; when the excitation current value is greater than the maximum excitation current value, adjust the excitation current value to the maximum excitation current value, and control the input current of the permanent magnet synchronous motor based on the adjusted excitation current.

[0130] In one embodiment, the motor data acquisition module 501 is further used to acquire the DC bus voltage of the permanent magnet synchronous motor, the pre-set back electromotive force constant, and the basic magnetic field strength provided by the permanent magnet; and to obtain the speed threshold based on the DC bus voltage, the back electromotive force constant, and the basic magnetic field strength.

[0131] Each module in the aforementioned permanent magnet synchronous motor control device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of the controller in hardware form or independent of it, or stored in the memory of the controller in software form, so that the processor can call and execute the corresponding operations of each module.

[0132] In one exemplary embodiment, a controller is provided, the internal structure of which can be as follows: Figure 6 As shown, the controller includes a processor and a memory. The processor provides computational and control capabilities. The memory includes a non-volatile storage medium storing a computer program. When executed by the processor, the computer program implements a permanent magnet synchronous motor control method.

[0133] Those skilled in the art will understand that Figure 6 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device (controller) to which the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0134] In one exemplary embodiment, a controller is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0135] In one exemplary embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above-described method embodiments.

[0136] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0137] The user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0138] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program mentioned can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0139] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0140] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A control method for a permanent magnet synchronous motor, characterized in that, The method includes: The motor speed of the permanent magnet synchronous motor to be controlled, the target torque of the permanent magnet synchronous motor, and the speed threshold of the permanent magnet synchronous motor are obtained; the rotor of the permanent magnet synchronous motor includes a permanent magnet and an electrically excited winding; the motor speed is compared with the speed threshold. When the motor speed is less than the speed threshold, the excitation current input to the electric excitation winding is obtained according to the target torque; When the motor speed is greater than or equal to the speed threshold, the maximum allowable back electromotive force of the permanent magnet synchronous motor is obtained, and the excitation current input to the electric excitation winding is obtained based on the maximum allowable back electromotive force. The input current of the permanent magnet synchronous motor is controlled based on the excitation current.

2. The method according to claim 1, characterized in that, When the motor speed is less than the speed threshold, the excitation current is calculated through the following steps: Obtain the basic magnetic field strength provided by the permanent magnet; The target rotor magnetic field strength is obtained based on the target torque; The excitation current is obtained based on the difference between the target rotor magnetic field strength and the base magnetic field strength, and the excitation coefficient of the electrically excited winding.

3. The method according to claim 1, characterized in that, When the motor speed is greater than or equal to the speed threshold, the excitation current is calculated through the following steps: Obtain the pre-set back electromotive force constant and the basic magnetic field strength provided by the permanent magnet; The target rotor magnetic field strength is obtained based on the maximum permissible back electromotive force, the back electromotive force constant, and the motor speed. The excitation current is obtained based on the difference between the target rotor magnetic field strength and the base magnetic field strength, and the excitation coefficient of the electrically excited winding.

4. The method according to claim 3, characterized in that, The step of obtaining the maximum permissible back electromotive force of the permanent magnet synchronous motor includes: Obtain the DC bus voltage of the permanent magnet synchronous motor; The maximum permissible back electromotive force is obtained based on the DC bus voltage and the preset back electromotive force safety factor.

5. The method according to claim 1, characterized in that, The method further includes: Based on the excitation current, the first magnetic flux corresponding to the electrically excited winding is obtained, and based on the first magnetic flux and the second magnetic flux corresponding to the permanent magnet, the rotor magnetic flux corresponding to the rotor is obtained. Based on the rotor flux linkage and the target torque, the quadrature-axis component of the stator current input to the stator of the permanent magnet synchronous motor is obtained, and the direct-axis component of the stator current is set to zero. The control of the input current of the permanent magnet synchronous motor based on the excitation current includes: The input current of the permanent magnet synchronous motor is controlled based on the quadrature-axis and direct-axis components of the excitation current and the stator current.

6. The method according to any one of claims 1 to 5, characterized in that, The control of the input current of the permanent magnet synchronous motor based on the excitation current includes: Obtain the preset maximum excitation current; When the value of the excitation current is less than or equal to the maximum value of the excitation current, the input current of the permanent magnet synchronous motor is controlled based on the excitation current; If the current value of the excitation current is greater than the maximum value of the excitation current, the current value of the excitation current is adjusted to the maximum value of the excitation current, and the input current of the permanent magnet synchronous motor is controlled based on the adjusted excitation current.

7. The method according to any one of claims 1 to 5, characterized in that, The speed threshold of the permanent magnet synchronous motor is obtained through the following steps: The DC bus voltage of the permanent magnet synchronous motor, the pre-set back electromotive force constant, and the basic magnetic field strength provided by the permanent magnet are obtained. The rotational speed threshold is obtained based on the DC bus voltage, the back electromotive force constant, and the basic magnetic field strength.

8. A control device for a permanent magnet synchronous motor, characterized in that, The device includes: The motor data acquisition module is used to acquire the motor speed of the permanent magnet synchronous motor to be controlled, the target torque of the permanent magnet synchronous motor, and the speed threshold of the permanent magnet synchronous motor; the rotor of the permanent magnet synchronous motor includes a permanent magnet and an electrically excited winding; the motor speed is compared with the speed threshold. The first excitation current acquisition module is used to acquire the excitation current input to the electric excitation winding based on the target torque when the motor speed is less than the speed threshold. The second excitation current acquisition module is used to acquire the maximum allowable back electromotive force of the permanent magnet synchronous motor when the motor speed is greater than or equal to the speed threshold, and to acquire the excitation current input to the electric excitation winding based on the maximum allowable back electromotive force. The permanent magnet motor control module is used to control the input current of the permanent magnet synchronous motor based on the excitation current.

9. A controller comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

11. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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