Method and system for implementing an electrically driven retarder

Abstract

The application relates to an implementation method and system of an electric brake, wherein the method comprises the following steps: when a brake pedal is triggered, requesting a brake power generation torque to be transmitted to a motor controller through a vehicle domain controller; based on the power generation torque, traversing a target query table to obtain a target direct-axis current and a target cross-axis current of a permanent magnet synchronous motor; based on the motor controller, converting the target direct-axis current and the target cross-axis current into energy, and distributing the converted energy to the motor and a battery system; when the voltage in the battery exceeds a preset value, based on the target query table, obtaining new target direct-axis current and new target cross-axis current of the permanent magnet synchronous motor, and distributing the new target direct-axis current and the new target cross-axis current to reduce the voltage in the battery system. The application timely converts brake force into heat to be consumed, reduces energy recovery, and reduces the wear of a mechanical brake.

Description

Technical Field

[0001] This application relates to the field of electric vehicle control technology, and in particular to a method and system for implementing an electric retarder. Background Technology

[0002] Currently, electric motors in new energy electric vehicles complete the conversion between electrical energy and mechanical energy. An electric retarder is a slowing device that uses an electric motor connected to the drive wheels to slow down the vehicle. This effect is achieved by converting the electric motor into a generator.

[0003] The driver uses the accelerator and brake pedals to generate corresponding electric torque or generator torque, which is then output to the motor controller. The motor controller converts the required torque into a corresponding current, thereby generating driving force or braking force. However, existing point-to-point retarders, when encountering special road conditions such as long downhill slopes, and when the battery voltage is high, cannot convert the braking force into heat in time for dissipation, leading to increased energy recovery and increased wear on the mechanical brakes. Summary of the Invention

[0004] The purpose of this application is to provide a method and system for implementing an electric retarder, so as to convert braking force into heat and dissipate it in a timely manner, thereby reducing energy recovery and reducing wear on mechanical brakes.

[0005] To address the aforementioned technical problems, embodiments of this application provide a method for implementing an electric retarder, comprising:

[0006] When the brake pedal is triggered, the vehicle domain controller requests the transmission of braking torque to the motor controller.

[0007] The target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor are obtained by traversing the target lookup table based on the generated torque.

[0008] The motor controller converts the target direct-axis current and the target quadrature-axis current into energy, and distributes the converted energy to the motor and battery system.

[0009] When the voltage in the battery exceeds a preset value, the new target direct-axis current and the new target quadrature-axis current of the permanent magnet synchronous motor are obtained based on the target lookup table, and the new target direct-axis current and the new target quadrature-axis current are allocated to reduce the charging energy in the battery system.

[0010] Furthermore, the step of converting the target direct-axis current and the target quadrature-axis current into energy based on the motor controller, and distributing the converted energy to the motor and battery system, includes:

[0011] In the motor controller, the target direct-axis current and the target quadrature-axis current are transmitted to the current loop to calculate the direct-axis voltage and quadrature-axis voltage of the permanent magnet synchronous motor.

[0012] The direct-axis voltage and the quadrature-axis voltage are transmitted to space vector pulse width modulation for energy conversion. The converted energy is distributed to the motor, and the converted energy is fed back to the battery system through the current loop after coordinate transformation.

[0013] Furthermore, the direct-axis voltage and quadrature-axis voltage of the permanent magnet synchronous motor are calculated using the voltage equation of the embedded permanent magnet synchronous motor.

[0014] The voltage equation of the embedded permanent magnet synchronous motor is as follows:

[0015]

[0016]

[0017] Where Rs is the stator resistance of the permanent magnet synchronous motor, Ld is the direct-axis inductance of the permanent magnet synchronous motor, Lq is the quadrature-axis inductance of the permanent magnet synchronous motor, Id is the target direct-axis current of the permanent magnet synchronous motor, Iq is the target quadrature-axis current of the permanent magnet synchronous motor, Ψf is the permanent magnet flux linkage of the permanent magnet synchronous motor, We is the electric angular velocity of the permanent magnet synchronous motor, Ud is the direct-axis voltage of the permanent magnet synchronous motor, and Uq is the quadrature-axis voltage of the permanent magnet synchronous motor.

[0018] Further, before obtaining the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor by traversing the target lookup table based on the generated torque, the following steps are included:

[0019] The maximum torque curve and the isotor curve are constructed based on the torque equation of the embedded permanent magnet synchronous motor.

[0020] Constructing an equal current circle based on the voltage equation of a permanent magnet synchronous motor in steady state;

[0021] The target lookup table constructs the relationship between torque and current based on the maximum torque curve, the constant torque curve, and the constant current circle.

[0022] Further, the step of obtaining the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor by traversing the target lookup table based on the generated torque includes:

[0023] Obtain the target torque curve of the generated torque in the target lookup table;

[0024] Obtain the target torque curve, the location point where the maximum torque curve intersects the constant current circle from the lookup table, and obtain the target direct-axis current and the target quadrature-axis current of the permanent magnet synchronous motor corresponding to the location point.

[0025] Furthermore, when the battery voltage exceeds a preset value, obtaining a new target direct-axis current and a new target quadrature-axis current of the permanent magnet synchronous motor based on the target lookup table, and allocating the new target direct-axis current and the new target quadrature-axis current to reduce the charging energy in the battery system, includes:

[0026] When the voltage in the battery exceeds a preset value, the vehicle domain controller requests the transmission of the generated torque to the motor controller.

[0027] The motor controller traverses the target lookup table to obtain the target position point where the isotor curve corresponding to the power generation torque intersects only with the isocurrent circle, and obtains the new target direct-axis current and the new target quadrature-axis current corresponding to the target position point.

[0028] The motor controller performs energy conversion between the new target direct-axis current and the new target quadrature-axis current, and distributes the converted energy to the motor and the battery system to reduce the charging energy in the battery system.

[0029] Furthermore, the voltage equation of the permanent magnet synchronous motor in steady state is as follows:

[0030] Ud = Rs * Id - Lq * Iq * We;

[0031]

[0032] Where Rs is the stator resistance of the permanent magnet synchronous motor, Ld is the direct-axis inductance of the permanent magnet synchronous motor, Lq is the quadrature-axis inductance of the permanent magnet synchronous motor, Id is the target direct-axis current of the permanent magnet synchronous motor, Iq is the target quadrature-axis current of the permanent magnet synchronous motor, Ψf is the permanent magnet flux linkage of the permanent magnet synchronous motor, We is the electric angular velocity of the permanent magnet synchronous motor, Ud is the direct-axis voltage of the permanent magnet synchronous motor, and Uq is the quadrature-axis voltage of the permanent magnet synchronous motor.

[0033] To address the aforementioned technical problems, embodiments of this application provide a system for implementing an electric retarder, comprising:

[0034] The generator torque transmission unit is used to request the transmission of braking generator torque to the motor controller through the vehicle domain controller when the brake pedal is triggered;

[0035] The target current acquisition unit is used to obtain the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor by traversing the target lookup table based on the generated torque.

[0036] An energy conversion unit is used to convert the target direct-axis current and the target quadrature-axis current into energy based on the motor controller, and to distribute the converted energy to the motor and battery system.

[0037] The current redistribution unit is used to obtain a new target direct-axis current and a new target quadrature-axis current of the permanent magnet synchronous motor based on the target lookup table when the voltage in the battery exceeds a preset value, and to distribute the new target direct-axis current and the new target quadrature-axis current to reduce the charging energy in the battery system.

[0038] Furthermore, the energy conversion unit includes:

[0039] A voltage calculation unit is used in the motor controller to transmit the target direct-axis current and the target quadrature-axis current to the current loop to calculate the direct-axis voltage and quadrature-axis voltage of the permanent magnet synchronous motor.

[0040] An energy distribution unit is used to transmit the direct-axis voltage and the quadrature-axis voltage to space vector pulse width modulation for energy conversion, distribute the converted energy to the motor, and feed the converted energy back to the battery system through the current loop after coordinate transformation.

[0041] This invention provides a method and system for implementing an electric retarder. The method includes: when the brake pedal is triggered, requesting the transmission of braking torque to the motor controller via the vehicle domain controller; obtaining the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor by traversing a target lookup table based on the generated torque; converting the target direct-axis current and target quadrature-axis current into energy based on the motor controller, and distributing the converted energy to the motor and battery system; when the battery voltage exceeds a preset value, obtaining a new target direct-axis current and a new target quadrature-axis current of the permanent magnet synchronous motor based on the target lookup table, and distributing the new target direct-axis current and the new target quadrature-axis current to reduce the charging energy in the battery system. This invention addresses situations where an electric vehicle encounters special road conditions such as long downhill slopes, and when the battery voltage is high, preventing the generation of large amounts of regenerative energy, by reducing the motor current distribution and lowering the power generation efficiency, thereby converting the braking force into heat for consumption, thus reducing energy recovery and wear on the mechanical brakes. Attached Figure Description

[0042] To more clearly illustrate the solutions in this application, the accompanying drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a flowchart illustrating the implementation method of the electric retarder provided in this application embodiment;

[0044] Figure 2 This is an overall control block diagram provided in one embodiment of this application;

[0045] Figure 3 This is a flowchart illustrating the implementation method of an electric retarder according to another embodiment of this application;

[0046] Figure 4 This is a schematic diagram of the motor voltage limit circle and current limit circle provided in the embodiments of this application;

[0047] Figure 5 This is a schematic diagram of motor current and torque distribution provided in an embodiment of this application;

[0048] Figure 6 This is a flowchart illustrating the implementation of a sub-process in the method for implementing an electric retarder provided in this application embodiment;

[0049] Figure 7 This is a flowchart illustrating the implementation of a sub-process in the method for implementing an electric retarder provided in this application embodiment;

[0050] Figure 8 This is a control block diagram of the motor controller provided in the embodiments of this application;

[0051] Figure 9 This is a flowchart illustrating the implementation of a sub-process in the method for implementing an electric retarder provided in this application embodiment;

[0052] Figure 10 This is a schematic diagram of the implementation system of the electric retarder provided in the embodiments of this application. Detailed Implementation

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0054] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0055] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0056] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0057] It should be noted that the implementation method of the electric retarder provided in this application embodiment is generally executed by a car, and correspondingly, the implementation system of the electric retarder is generally configured in a car.

[0058] Please see Figure 1 and Figure 2 , Figure 1 One specific implementation method of the electric retarder is shown. Figure 2 This is an overall control block diagram provided in one embodiment of this application.

[0059] It should be noted that if substantially the same result is obtained, the method of this invention is not based on... Figure 1 Limited to the order of the processes shown, this method includes the following steps:

[0060] S1: When the brake pedal is triggered, the vehicle domain controller requests the transmission of braking torque to the motor controller.

[0061] In this embodiment, when the driver presses the brake pedal, the brake pedal is triggered, and the vehicle domain controller (VCU) requests the transmission of the braking torque Te to the motor controller. When the battery's SOC is low, the battery allows a large charging current; when the battery's SOC is high, the battery does not allow a large charging current. SOC (state of charge) refers to the ratio of the battery's remaining capacity after a period of use or long-term disuse to its fully charged capacity, usually expressed as a percentage. Its value ranges from 0 to 1; when SOC = 0, the battery is fully discharged; when SOC = 1, the battery is fully charged.

[0062] S2: Based on the generated torque, traverse the target lookup table to obtain the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor.

[0063] In this embodiment, the motor controller iterates through a pre-built target lookup table to obtain the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor. The current distribution at this time makes the electronic control system most efficient, which allows the generated energy from braking to be recovered into the battery system.

[0064] Please see Figures 3 to 5 , Figure 3 A specific implementation prior to step S2 is shown. Figure 4 This is a schematic diagram of the motor voltage limit circle and current limit circle provided in the embodiments of this application; Figure 5 This is a schematic diagram of motor current and torque distribution provided in an embodiment of this application, detailed below:

[0065] S2A: Constructing the maximum torque curve and the isotor curve based on the torque equation of the embedded permanent magnet synchronous motor.

[0066] Furthermore, the torque equation of the embedded permanent magnet synchronous motor is as follows:

[0067] Te=1.5*Np*(Ψf*Iq+(Ld-Lq)*Id*Iq) (1);

[0068]

[0069] Where Te is the electromagnetic torque, Np is the number of pole pairs of the motor, Ψf is the permanent magnet flux linkage of the permanent magnet synchronous motor, Iq is the quadrature axis current of the permanent magnet synchronous motor, Id is the direct axis current of the permanent magnet synchronous motor, Ld is the direct axis inductance of the permanent magnet synchronous motor, and Lq is the quadrature axis inductance of the permanent magnet synchronous motor.

[0070] Specifically, based on the torque equation of the embedded permanent magnet synchronous motor, it can be seen that the electromagnetic torque Te, the direct-axis current Id, and the direct-axis current Iq have maximum extreme values, and the minimum Id and Iq output the maximum electromagnetic torque Te, thus constructing the maximum torque (MTPA) curve. Using the above formula (1), different direct-axis currents Id and Iq under the same electromagnetic torque can be obtained, thus constructing the constant torque curves T1, T2, T3, and T4 as shown in Figure 5.

[0071] S2B: Constructing an equal current circle based on the voltage equation of a permanent magnet synchronous motor in steady state.

[0072] Furthermore, the voltage equation of the permanent magnet synchronous motor in steady state is as follows:

[0073] Ud=Rs*Id-Lq*Iq*We (4);

[0074] Uq=Rs*Iq-Ld*Id*We+Ψf*We (5);

[0075] Where Rs is the stator resistance of the permanent magnet synchronous motor, Ld is the direct-axis inductance of the permanent magnet synchronous motor, Lq is the quadrature-axis inductance of the permanent magnet synchronous motor, Id is the target direct-axis current of the permanent magnet synchronous motor, Iq is the target quadrature-axis current of the permanent magnet synchronous motor, Ψf is the permanent magnet flux linkage of the permanent magnet synchronous motor, We is the electric angular velocity of the permanent magnet synchronous motor, Ud is the direct-axis voltage of the permanent magnet synchronous motor, and Uq is the quadrature-axis voltage of the permanent magnet synchronous motor.

[0076] Specifically, a practical motor controller is a power electronic product with a rated capacity. This rated capacity limits the input voltage and current to the motor's terminals. The constraints on the motor are expressed as voltage and current constraints. Without modulation, the maximum output voltage of the motor controller is:

[0077]

[0078] Where Udc is the controller bus voltage and Umax is the maximum phase voltage that the controller can output.

[0079] The voltage constraint condition is:

[0080] Ud 2 +Uq 2 ≤Umax 2 (7);

[0081] After simplifying the above formulas (4), (5), (6), and (7), we obtain the voltage limit circle equation for the built-in permanent magnet synchronous motor:

[0082]

[0083] According to the above formula (8), the following can be constructed: Figure 4 The motor voltage limit circle in the diagram.

[0084] Furthermore, the current constraint condition is as follows:

[0085] Id 2 +Iq 2 ≤Ismax 2 (9);

[0086] Based on the above formula (9), the following can be constructed: Figure 4 and Figure 5 Similarly, the current limiting circle in [the diagram] can be constructed for different values ​​of Id and Iq, as shown below. Figure 5 Different isocurrent circles in the diagram.

[0087] S2C: Construct the target lookup table of the correspondence between torque and current based on the maximum torque curve, the constant torque curve, and the constant current circle.

[0088] Specifically, the above steps have already constructed the maximum torque curve, the constant torque curve, and the constant current circle. Therefore, these curves can be projected onto the same coordinate system to obtain the correspondence between current and torque, thereby constructing the target lookup table.

[0089] Please see Figure 6 , Figure 6 A specific implementation of step S2 is shown below:

[0090] S21: Obtain the target torque curve of the generated torque in the target lookup table.

[0091] S22: Obtain the target torque curve, the position point where the maximum torque curve intersects with the isocurrent circle from the lookup table, and obtain the target direct-axis current and the target quadrature-axis current of the permanent magnet synchronous motor corresponding to the position point.

[0092] In this embodiment, the generator torque is obtained from the target torque curve in the target lookup table through the motor controller. The location points where the target torque curve, the maximum torque curve, and the constant current circle intersect are obtained from the lookup table. The target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor corresponding to these location points are also obtained. In a specific embodiment, such as... Figure 5 As shown, if the generated torque is T2, then the equal torque curve can be obtained, and the point where it intersects with the maximum torque curve and the equal current circle can be found, that is... Figure 6 At point B, obtain the direct-axis current and quadrature-axis current of the permanent magnet synchronous motor at point B, and use them as the target direct-axis current and target quadrature-axis current.

[0093] S3: Based on the motor controller, the target direct-axis current and the target quadrature-axis current are converted into energy, and the converted energy is distributed to the motor and battery system.

[0094] Please see Figure 7 and Figure 8 , Figure 7 One specific implementation of step S3 is shown. Figure 8 The control block diagram of the motor controller provided in this application embodiment is described in detail below:

[0095] S31: In the motor controller, the target direct-axis current and the target quadrature-axis current are transmitted to the current loop to calculate the direct-axis voltage and quadrature-axis voltage of the permanent magnet synchronous motor.

[0096] Furthermore, the direct-axis voltage and quadrature-axis voltage of the permanent magnet synchronous motor are calculated using the voltage equation of the embedded permanent magnet synchronous motor.

[0097] The voltage equation of the embedded permanent magnet synchronous motor is as follows:

[0098]

[0099]

[0100] Where Rs is the stator resistance of the permanent magnet synchronous motor, Ld is the direct-axis inductance of the permanent magnet synchronous motor, Lq is the quadrature-axis inductance of the permanent magnet synchronous motor, Id is the target direct-axis current of the permanent magnet synchronous motor, Iq is the target quadrature-axis current of the permanent magnet synchronous motor, Ψf is the permanent magnet flux linkage of the permanent magnet synchronous motor, We is the electric angular velocity of the permanent magnet synchronous motor, Ud is the direct-axis voltage of the permanent magnet synchronous motor, and Uq is the quadrature-axis voltage of the permanent magnet synchronous motor.

[0101] In this embodiment, the target direct-axis current and the target quadrature-axis current are transmitted to the current loop to calculate the direct-axis voltage and quadrature-axis voltage of the permanent magnet synchronous motor. The direct-axis voltage and quadrature-axis voltage of the permanent magnet synchronous motor are calculated by substituting the target direct-axis current and the target quadrature-axis current into the above formulas (10) and (11), respectively.

[0102] S32: The direct-axis voltage and the quadrature-axis voltage are transmitted to space vector pulse width modulation for energy conversion, the converted energy is distributed to the motor, and the converted energy is fed back to the battery system through the current loop after coordinate transformation.

[0103] In this embodiment, the direct-axis voltage and quadrature-axis voltage are transmitted to Space Vector Pulse Width Modulation (SVPWM) for energy conversion. The converted energy is then distributed to the motor, and after coordinate transformation, it is fed back to the battery system via a current loop. The main idea of ​​SVPWM is to use the ideal flux linkage circle of the three-phase symmetrical motor stator when powered by a three-phase symmetrical sinusoidal voltage as a reference standard. Different switching modes of the three-phase inverter are used to appropriately switch and generate a PWM wave, and the resulting actual flux linkage vector is used to track its accurate flux linkage circle.

[0104] S4: When the voltage in the battery exceeds the preset value, obtain the new target direct-axis current and the new target quadrature-axis current of the permanent magnet synchronous motor based on the target lookup table, and allocate the new target direct-axis current and the new target quadrature-axis current to reduce the charging energy in the battery system.

[0105] In this embodiment, if the battery voltage exceeds a preset value, that is, when the battery SOC is too high, the battery does not allow for a large amount of energy recovery. In this case, it is necessary to obtain a new target direct-axis current and a new target quadrature-axis current, and distribute the new target direct-axis current and the new target quadrature-axis current to reduce the system's power generation efficiency and reduce the power generation current, thereby reducing the charging energy in the battery system, so that the braking energy is converted into the motor's heat energy for consumption, reducing the charging of the high SOC battery, and reducing the wear of the mechanical brake.

[0106] Please see Figure 9 , Figure 9 A specific implementation of step S4 is shown below:

[0107] S41: When the voltage in the battery exceeds a preset value, the vehicle domain controller requests the transmission of the generated torque to the motor controller.

[0108] S42: The motor controller traverses the target lookup table to obtain the target position point where the isotor curve corresponding to the power generation torque intersects only with the isocurrent circle, and obtains the new target direct-axis current and the new target quadrature-axis current corresponding to the target position point.

[0109] S43: Based on the motor controller, the new target direct-axis current and the new target quadrature-axis current are converted into energy, and the converted energy is distributed to the motor and the battery system to reduce the charging energy in the battery system.

[0110] Specifically, formulas (6) and (7) above can calculate the maximum output voltage and voltage constraint conditions, so it can be used to determine whether the voltage in the battery exceeds the preset value. When it exceeds the preset value, the vehicle domain controller requests the transmission of braking and generating torque to the motor controller. The motor controller then traverses the target lookup table to obtain the target position point where the isotor curve corresponding to the generating torque intersects only with the isocurrent circle, and obtains the new target direct-axis current and the new target quadrature-axis current corresponding to the target position point. Figure 5 As shown, the target location is point C. The power generation efficiency at point C is lower than that at point B. Therefore, the new target direct-axis current and the new target quadrature-axis current corresponding to point C are redistributed to reduce the system's power generation efficiency, causing braking energy to be converted into motor heat energy for consumption, reducing the charging of the high-SOC battery, and reducing wear on the mechanical brakes. It should be noted that the allocation process of the new target direct-axis current and the new target quadrature-axis current is the same as steps S31 and S32 above; to avoid repetition, it will not be described again here.

[0111] In this embodiment, when the brake pedal is triggered, the vehicle domain controller requests the transmission of braking torque to the motor controller. Based on the generated torque, a target lookup table is traversed to obtain the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor. The motor controller performs energy conversion on the target direct-axis current and the target quadrature-axis current, and distributes the converted energy to the motor and battery system. When the battery voltage exceeds a preset value, a new target direct-axis current and a new target quadrature-axis current of the permanent magnet synchronous motor are obtained based on the target lookup table, and the new target direct-axis current and the new target quadrature-axis current are distributed to reduce the charging energy in the battery system. In this embodiment, when an electric vehicle encounters special road conditions such as a long downhill slope, and when the battery voltage is high, it is not permissible to generate large amounts of regenerative energy. This can be achieved by reducing the power generation efficiency through motor current distribution, thereby converting the braking force into heat for consumption, thus reducing energy recovery and wear on the mechanical brakes.

[0112] Please refer to Figure 10 As a response to the above Figure 1 The present application provides an embodiment of an electric retarder implementation system, which is similar to the method shown. Figure 1 Corresponding to the method embodiments shown, the system can be specifically applied to various automobiles.

[0113] like Figure 10 As shown, the implementation system of the electric retarder in this embodiment includes: a power generation torque transmission unit 51, a target current acquisition unit 52, an energy conversion unit 53, and a current redistribution unit 54, wherein:

[0114] The power generation torque transmission unit 51 is used to request the transmission of braking power generation torque to the motor controller through the vehicle domain controller when the brake pedal is triggered.

[0115] The target current acquisition unit 52 is used to obtain the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor by traversing the target lookup table based on the generated torque.

[0116] The energy conversion unit 53 is used to convert the target direct-axis current and the target quadrature-axis current into energy based on the motor controller, and distribute the converted energy to the motor and battery system.

[0117] The current redistribution unit 54 is used to obtain a new target direct-axis current and a new target quadrature-axis current of the permanent magnet synchronous motor based on the target lookup table when the voltage in the battery exceeds a preset value, and to distribute the new target direct-axis current and the new target quadrature-axis current to reduce the charging energy in the battery system.

[0118] Furthermore, the energy conversion unit 53 includes:

[0119] A voltage calculation unit is used in the motor controller to transmit the target direct-axis current and the target quadrature-axis current to the current loop to calculate the direct-axis voltage and quadrature-axis voltage of the permanent magnet synchronous motor.

[0120] An energy distribution unit is used to transmit the direct-axis voltage and the quadrature-axis voltage to space vector pulse width modulation for energy conversion, distribute the converted energy to the motor, and feed the converted energy back to the battery system through the current loop after coordinate transformation.

[0121] Furthermore, the system also includes a voltage calculation unit, used to calculate the direct-axis voltage and quadrature-axis voltage of the permanent magnet synchronous motor using the voltage equation of the embedded permanent magnet synchronous motor.

[0122] Furthermore, the voltage equation of the embedded permanent magnet synchronous motor is as follows:

[0123]

[0124]

[0125] Where Rs is the stator resistance of the permanent magnet synchronous motor, Ld is the direct-axis inductance of the permanent magnet synchronous motor, Lq is the quadrature-axis inductance of the permanent magnet synchronous motor, Id is the target direct-axis current of the permanent magnet synchronous motor, Iq is the target quadrature-axis current of the permanent magnet synchronous motor, Ψf is the permanent magnet flux linkage of the permanent magnet synchronous motor, We is the electric angular velocity of the permanent magnet synchronous motor, Ud is the direct-axis voltage of the permanent magnet synchronous motor, and Uq is the quadrature-axis voltage of the permanent magnet synchronous motor.

[0126] Furthermore, the target current acquisition unit 52 also includes:

[0127] The curve construction unit is used to construct the maximum torque curve and the isotor curve based on the torque equation of the embedded permanent magnet synchronous motor.

[0128] An isocurrent circle construction unit is used to construct an isocurrent circle based on the voltage equation of a permanent magnet synchronous motor in steady state.

[0129] The target lookup table construction unit is used to construct the target lookup table of the correspondence between torque and current based on the maximum torque curve, the constant torque curve, and the constant current circle.

[0130] Furthermore, the target current acquisition unit 52 includes:

[0131] A target torque curve acquisition unit is used to acquire the target torque curve of the generated torque in the target lookup table;

[0132] The current acquisition unit is used to obtain the target torque curve, the position point where the maximum torque curve intersects with the isocurrent circle in the lookup table, and to obtain the target direct-axis current and the target quadrature-axis current of the permanent magnet synchronous motor corresponding to the position point.

[0133] Furthermore, the current redistribution unit 54 includes:

[0134] A braking request unit is used to request the transmission of the generated torque to the motor controller via the vehicle domain controller when the voltage in the battery exceeds a preset value.

[0135] The target location point acquisition unit is used to traverse the target lookup table through the motor controller to obtain the target location point where the isotor curve corresponding to the power generation torque intersects only the isocurrent circle, and to obtain the new target direct-axis current and the new target quadrature-axis current corresponding to the target location point;

[0136] The voltage reduction unit is used to convert the new target direct-axis current and the new target quadrature-axis current into energy based on the motor controller, and distribute the converted energy to the motor and the battery system to reduce the charging energy in the battery system.

[0137] Furthermore, the voltage equation of the permanent magnet synchronous motor in steady state is as follows:

[0138] Ud = Rs * Id - Lq * Iq * We;

[0139] Uq = Rs*Iq - Ld*Id*We + Ψf*We;

[0140] Where Rs is the stator resistance of the permanent magnet synchronous motor, Ld is the direct-axis inductance of the permanent magnet synchronous motor, Lq is the quadrature-axis inductance of the permanent magnet synchronous motor, Id is the target direct-axis current of the permanent magnet synchronous motor, Iq is the target quadrature-axis current of the permanent magnet synchronous motor, Ψf is the permanent magnet flux linkage of the permanent magnet synchronous motor, We is the electric angular velocity of the permanent magnet synchronous motor, Ud is the direct-axis voltage of the permanent magnet synchronous motor, and Uq is the quadrature-axis voltage of the permanent magnet synchronous motor.

[0141] Furthermore, the torque equation of the embedded permanent magnet synchronous motor is as follows:

[0142] Te=1.5*Np*(Ψf*Iq+(Ld-Lq)*Id*Iq);

[0143]

[0144] Where Te is the electromagnetic torque, Np is the number of pole pairs of the motor, Ψf is the permanent magnet flux linkage of the permanent magnet synchronous motor, Iq is the quadrature axis current of the permanent magnet synchronous motor, and Id is the direct axis current of the permanent magnet synchronous motor.

[0145] In this embodiment, when the brake pedal is triggered, the vehicle domain controller requests the transmission of braking torque to the motor controller. Based on the generated torque, a target lookup table is traversed to obtain the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor. The motor controller performs energy conversion on the target direct-axis current and the target quadrature-axis current, and distributes the converted energy to the motor and battery system. When the battery voltage exceeds a preset value, a new target direct-axis current and a new target quadrature-axis current of the permanent magnet synchronous motor are obtained based on the target lookup table, and the new target direct-axis current and the new target quadrature-axis current are distributed to reduce the charging energy in the battery system. In this embodiment, when an electric vehicle encounters special road conditions such as a long downhill slope, and when the battery voltage is high, it is not permissible to generate large amounts of regenerative energy. This can be achieved by reducing the power generation efficiency through motor current distribution, thereby converting the braking force into heat for consumption, thus reducing energy recovery and wear on the mechanical brakes.

[0146] Obviously, the embodiments described above are only some embodiments of this application, not all embodiments. The accompanying drawings show preferred embodiments of this application, but do not limit the patent scope of this application. This application can be implemented in many different forms; rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this application's specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this application.

Claims

1. A method for implementing an electric retarder, characterized in that, include: When the brake pedal is triggered, the vehicle domain controller requests the transmission of braking torque to the motor controller. The maximum torque curve and the isotor curve are constructed based on the torque equation of the embedded permanent magnet synchronous motor. Constructing an equal current circle based on the voltage equation of a permanent magnet synchronous motor in steady state; A target lookup table for the correspondence between torque and current is constructed based on the maximum torque curve, the constant torque curve, and the constant current circle. Based on the generated torque, the target lookup table is traversed to obtain the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor; The motor controller converts the target direct-axis current and the target quadrature-axis current into energy, and distributes the converted energy to the motor and battery system. When the voltage in the battery exceeds a preset value, the new target direct-axis current and the new target quadrature-axis current of the permanent magnet synchronous motor are obtained based on the target lookup table, and the new target direct-axis current and the new target quadrature-axis current are allocated to reduce the charging energy in the battery system. When the battery voltage exceeds a preset value, a new target direct-axis current and a new target quadrature-axis current of the permanent magnet synchronous motor are obtained based on the target lookup table, and the new target direct-axis current and the new target quadrature-axis current are allocated to reduce the charging energy of the battery system, including: When the voltage in the battery exceeds a preset value, the vehicle domain controller requests the transmission of the generated torque to the motor controller. The motor controller traverses the target lookup table to obtain the target position point where the isotor curve corresponding to the power generation torque intersects only with the isocurrent circle, and obtains the new target direct-axis current and the new target quadrature-axis current corresponding to the target position point. The motor controller performs energy conversion between the new target direct-axis current and the new target quadrature-axis current, and distributes the converted energy to the motor and the battery system to reduce the charging energy in the battery system.

2. The method for implementing the electric retarder according to claim 1, characterized in that, The process of converting the target direct-axis current and the target quadrature-axis current into energy based on the motor controller, and distributing the converted energy to the motor and battery system, includes: In the motor controller, the target direct-axis current and the target quadrature-axis current are transmitted to the current loop to calculate the direct-axis voltage and quadrature-axis voltage of the permanent magnet synchronous motor. The direct-axis voltage and the quadrature-axis voltage are transmitted to space vector pulse width modulation for energy conversion. The converted energy is distributed to the motor, and the converted energy is fed back to the battery system through the current loop after coordinate transformation.

3. The method for implementing the electric retarder according to claim 2, characterized in that, The direct-axis voltage and quadrature-axis voltage of the permanent magnet synchronous motor are calculated using the voltage equation of the embedded permanent magnet synchronous motor. The voltage equation of the embedded permanent magnet synchronous motor is as follows: ； ； Where Rs is the stator resistance of the permanent magnet synchronous motor, Ld is the direct-axis inductance of the permanent magnet synchronous motor, Lq is the quadrature-axis inductance of the permanent magnet synchronous motor, Id is the target direct-axis current of the permanent magnet synchronous motor, Iq is the target quadrature-axis current of the permanent magnet synchronous motor, Ψf is the permanent magnet flux linkage of the permanent magnet synchronous motor, We is the electric angular velocity of the permanent magnet synchronous motor, Ud is the direct-axis voltage of the permanent magnet synchronous motor, and Uq is the quadrature-axis voltage of the permanent magnet synchronous motor.

4. The method for implementing the electric retarder according to claim 1, characterized in that, The step of obtaining the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor by traversing the target lookup table based on the generated torque includes: Obtain the target torque curve of the generated torque in the target lookup table; Obtain the target torque curve, the location point where the maximum torque curve intersects the constant current circle from the lookup table, and obtain the target direct-axis current and the target quadrature-axis current of the permanent magnet synchronous motor corresponding to the location point.

5. The method for implementing the electric retarder according to claim 1, characterized in that, The voltage equation of the permanent magnet synchronous motor in steady state is as follows: ； ； Where Rs is the stator resistance of the permanent magnet synchronous motor, Ld is the direct-axis inductance of the permanent magnet synchronous motor, Lq is the quadrature-axis inductance of the permanent magnet synchronous motor, Id is the target direct-axis current of the permanent magnet synchronous motor, Iq is the target quadrature-axis current of the permanent magnet synchronous motor, Ψf is the permanent magnet flux linkage of the permanent magnet synchronous motor, We is the electric angular velocity of the permanent magnet synchronous motor, Ud is the direct-axis voltage of the permanent magnet synchronous motor, and Uq is the quadrature-axis voltage of the permanent magnet synchronous motor.

6. The method for implementing the electric retarder according to claim 1, characterized in that, The torque equation of the embedded permanent magnet synchronous motor is as follows: ； ； Where Te is the electromagnetic torque, Np is the number of pole pairs of the motor, Ψf is the permanent magnet flux linkage of the permanent magnet synchronous motor, Iq is the quadrature axis current of the permanent magnet synchronous motor, Id is the direct axis current of the permanent magnet synchronous motor, Ld is the direct axis inductance of the permanent magnet synchronous motor, and Lq is the quadrature axis inductance of the permanent magnet synchronous motor.

7. A system for implementing an electric retarder, characterized in that, include: The generator torque transmission unit is used to request the transmission of braking generator torque to the motor controller through the vehicle domain controller when the brake pedal is triggered; The curve construction unit is used to construct the maximum torque curve and the isotor curve based on the torque equation of the embedded permanent magnet synchronous motor. An isocurrent circle construction unit is used to construct an isocurrent circle based on the voltage equation of a permanent magnet synchronous motor in steady state. The target lookup table construction unit is used to construct a target lookup table of the correspondence between torque and current based on the maximum torque curve, the constant torque curve, and the constant current circle. The target current acquisition unit is used to traverse the target lookup table based on the generated torque to obtain the target direct-axis current and the target quadrature-axis current of the permanent magnet synchronous motor. An energy conversion unit is used to convert the target direct-axis current and the target quadrature-axis current into energy based on the motor controller, and to distribute the converted energy to the motor and battery system. A current redistribution unit is used to obtain a new target direct-axis current and a new target quadrature-axis current of the permanent magnet synchronous motor based on the target lookup table when the voltage in the battery exceeds a preset value, and to distribute the new target direct-axis current and the new target quadrature-axis current to reduce the charging energy in the battery system. The current redistribution unit includes: A braking request unit is used to request the transmission of the generated torque to the motor controller via the vehicle domain controller when the voltage in the battery exceeds a preset value. The target location point acquisition unit is used to traverse the target lookup table through the motor controller to obtain the target location point where the isotor curve corresponding to the power generation torque intersects only the isocurrent circle, and to obtain the new target direct-axis current and the new target quadrature-axis current corresponding to the target location point; The voltage reduction unit is used to convert the new target direct-axis current and the new target quadrature-axis current into energy based on the motor controller, and distribute the converted energy to the motor and the battery system to reduce the charging energy in the battery system.

8. The system for implementing the electric retarder according to claim 7, characterized in that, The energy conversion unit includes: A voltage calculation unit is used in the motor controller to transmit the target direct-axis current and the target quadrature-axis current to the current loop to calculate the direct-axis voltage and quadrature-axis voltage of the permanent magnet synchronous motor. An energy distribution unit is used to transmit the direct-axis voltage and the quadrature-axis voltage to space vector pulse width modulation for energy conversion, distribute the converted energy to the motor, and feed the converted energy back to the battery system through the current loop after coordinate transformation.

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