Implementation method and system of electric retarder

Abstract

The invention relates to an electric retarder implementation method and system.The method comprises the steps that when a brake pedal is triggered, braking power generation torque is requested to be transmitted to a motor controller through a whole vehicle domain controller; traversing the target look-up table based on the power generation torque to obtain a target direct-axis current and a target quadrature-axis current of the permanent magnet synchronous motor; performing energy conversion on the target direct-axis current and the target quadrature-axis current based on a motor controller, and distributing the converted energy to a motor and a battery system; and when the voltage in the battery 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 query table, and distributing the new target direct-axis current and the new target quadrature-axis current to reduce the voltage in the battery system. The braking force is timely converted into heat to be consumed, energy recovery is reduced, and abrasion of mechanical braking is reduced.

Description

Technical Field

[0001] The present application relates to the field of electric vehicle control technology, and in particular to an implementation method and system of an electric retarder. Background Art

[0002] At present, the motors on new energy electric vehicles complete the mutual conversion between electrical energy and mechanical energy. The electric retarder is a retarding device that uses the electric motor connected to the drive wheel to slow down the moving vehicle. This effect is achieved by turning the electric motor into a generator.

[0003] The driver generates corresponding electric torque or power generation torque through the accelerator pedal and the brake pedal, and outputs it to the motor controller. The motor controller converts the required torque into corresponding current to generate driving force or braking force. However, when the existing point-to-point retarder encounters special road conditions such as long downhill slopes and when the battery voltage is very high, it cannot convert the braking force into heat in time, resulting in increased energy recovery and increased wear of the mechanical brakes. Summary of the invention

[0004] The purpose of the embodiments of the present application is to propose a method and system for implementing an electric retarder, so as to timely convert the braking force into heat for consumption, reduce energy recovery and reduce the wear of mechanical brakes.

[0005] In order to solve the above technical problems, the embodiment of the present application provides a method for implementing an electric retarder, comprising:

[0006] When the brake pedal is triggered, the vehicle domain controller requests the brake power generation torque to be transmitted to the motor controller;

[0007] Traversing the target lookup table based on the power generation torque to obtain a target direct-axis current and a target quadrature-axis current of the permanent magnet synchronous motor;

[0008] 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 the battery system;

[0009] When the voltage in the battery 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 query 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.

[0010] Further, the method 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 the battery system includes:

[0011] In the motor controller, the target direct-axis current and the target quadrature-axis current are transmitted to a current loop to calculate the direct-axis voltage and the 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 conversion.

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

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

[0015]

[0016]

[0017] Among them, 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 electrical 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 traversing the target lookup table based on the power generation torque to obtain the target direct-axis current and the target quadrature-axis current of the permanent magnet synchronous motor, the method includes:

[0019] Construct the maximum torque curve and equal torque curve based on the torque equation of the embedded permanent magnet synchronous motor;

[0020] Construct equal current circles based on the voltage equation of the permanent magnet synchronous motor in steady state;

[0021] The target query table of the correspondence between torque and current is constructed based on the maximum torque curve, the equal torque curve and the equal current circle.

[0022] Further, the traversing the target lookup table based on the power generation torque to obtain the target direct-axis current and the target quadrature-axis current of the permanent magnet synchronous motor includes:

[0023] Acquire a target torque curve of the power generation torque in the target query table;

[0024] The target torque curve, the position point where the maximum torque curve intersects with the equal current circle are obtained in the query table, and the target direct-axis current and the target quadrature-axis current of the permanent magnet synchronous motor corresponding to the position point are obtained.

[0025] Further, when the voltage in the battery 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 query 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, including:

[0026] When the voltage in the battery exceeds a preset value, the vehicle domain controller is used to request braking to transmit the power generation torque to the motor controller;

[0027] Traversing the target query table through the motor controller to obtain a target position point where the equal torque curve corresponding to the power generation torque intersects only with the equal current circle, and obtaining the new target direct-axis current and the new target quadrature-axis current corresponding to the target position point;

[0028] 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.

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

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

[0031]

[0032] Among them, 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 electrical 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] In order to solve the above technical problems, the embodiment of the present application provides an implementation system of an electric retarder, comprising:

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

[0035] A target current acquisition unit, configured to traverse a target query table based on the power generation torque to acquire a target direct-axis current and a target quadrature-axis current of the permanent magnet synchronous motor;

[0036] an energy conversion unit, configured to perform energy conversion on the target direct-axis current and the target quadrature-axis current based on the motor controller, and distribute the converted energy to the motor and a battery system;

[0037] 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 query 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 comprises:

[0039] A voltage calculation unit, used for transmitting the target direct-axis current and the target quadrature-axis current to a current loop in the motor controller to calculate the direct-axis voltage and the quadrature-axis voltage of the permanent magnet synchronous motor;

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

[0041] The embodiment of the present invention provides a method and system for implementing an electric retarder. The method includes: when the brake pedal is triggered, requesting the braking power generation torque to be transmitted to the motor controller through the vehicle domain controller; traversing the target query table based on the power generation torque to obtain the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor; 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; when the voltage in the battery exceeds the preset value, obtaining the new target direct-axis current and the new target quadrature-axis current of the permanent magnet synchronous motor based on the target query 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. In the embodiment of the present invention, when the electric vehicle encounters special road conditions such as a long downhill, and when the battery voltage is very high, it is not allowed to generate a large amount of feedback energy. The motor current can be distributed to reduce the power generation efficiency, thereby converting the braking force into heat for consumption, thereby reducing energy recovery and mechanical brake wear. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the scheme in the present application, a brief introduction is given below to the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 is a flow chart of the implementation method of the electric retarder provided in the embodiment of the present application;

[0044] Figure 2 It is an overall control block diagram provided by an embodiment of the present application;

[0045] Figure 3 is a flow chart of an implementation method of an electric retarder provided in another embodiment of the present application;

[0046] Figure 4 is a schematic diagram of a motor voltage limit circle and a current limit circle provided in an embodiment of the present application;

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

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

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

[0050] Figure 8 is a control block diagram of a motor controller provided in an embodiment of the present application;

[0051] Fig. 9 is a flowchart of a sub-process in a method for implementing an electric retarder provided in an embodiment of the present application;

[0052] Fig.10 It is a schematic diagram of the implementation system of the electric retarder provided in the embodiment of the present application. DETAILED DESCRIPTION

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of the present application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0054] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

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

[0056] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0057] It should be noted that the implementation method of the electric retarder provided in the embodiment of the present application is generally executed by an automobile, and accordingly, the implementation system of the electric retarder is generally configured in an automobile.

[0058] See also Figure 1 and Figure 2 , Figure 1 A specific implementation method of the electric retarder is shown. Figure 2 It is an overall control block diagram provided by an embodiment of the present application.

[0059] It should be noted that if there are substantially the same results, the method of the present invention is not limited to Figure 1 The process sequence shown is limited to the following steps:

[0060] S1: When the brake pedal is triggered, the vehicle domain controller requests the braking power generation torque to be transmitted to the motor controller.

[0061] In the embodiment of the present application, when the driver steps on the brake pedal, the brake pedal is triggered, and the vehicle domain controller VCU requests the brake power generation torque Te to be transmitted to the motor controller; when the battery SOC is relatively low, the battery allows a large charging current; if the battery SOC is relatively high, the battery does not allow a large charging current. Among them, SOC (state of charge) refers to the state of charge, which is the ratio of the remaining capacity of the battery after a period of use or long-term unused to its fully charged capacity, usually expressed as a percentage. Its value range is 0 to 1. When SOC = 0, it means that the battery is fully discharged, and when SOC = 1, it means that the battery is fully charged.

[0062] S2: traversing the target lookup table based on the power generation torque to obtain the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor.

[0063] In an embodiment of the present application, a motor controller is used to traverse and query a pre-constructed target query 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, and the power generation energy generated by braking can be recovered to the battery system.

[0064] See also Figures 3 to 5 , Figure 3 A specific implementation method before step S2 is shown. Figure 4 is a schematic diagram of a motor voltage limit circle and a current limit circle provided in an embodiment of the present application; Figure 5 This is a schematic diagram of motor current and torque distribution provided in an embodiment of the present application, which is described in detail as follows:

[0065] S2A: Constructing the maximum torque curve and equal torque 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:

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

[0068]

[0069] Among them, Te is the electromagnetic torque, Np is the number of motor pole pairs, Ψf is the permanent magnet flux 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 known that the electromagnetic torque Te and the direct axis current Id and Iq have maximum extreme values, and the minimum Id and Iq output the maximum electromagnetic torque Te, thereby constructing the maximum torque (MTPA) curve. The above formula (1) can be used to obtain different direct axis currents Id and Iq under the same electromagnetic torque, thereby constructing equal torque curves T1, T2, T3, and T4 as shown in Figure 5.

[0071] S2B: Construction of equal current circles 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 the steady state is:

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

[0074] Uq=Rs*Iq-Ld*Id*We+Ψf*We (5);

[0075] Among them, 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 electrical 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, the actual motor controller is a power electronic product with a rated capacity. This rated capacity limits the terminal voltage and current input of the motor. The constraints on the motor are written as constraints on voltage and current. The maximum output voltage of the motor controller without overmodulation is:

[0077]

[0078] Among them, Udc is the bus voltage of the controller, and Umax is the maximum phase voltage that the controller can output.

[0079] The voltage constraints are:

[0080] Ud 2 +Uq 2 ≤Umax 2 (7);

[0081] After simplifying the above formulas (4)(5)(6)(7), the voltage limit circle equation of the interior permanent magnet synchronous motor is obtained:

[0082]

[0083] According to the above formula (8), we can construct Figure 4 The motor voltage limit circle in .

[0084] Furthermore, the current constraint is:

[0085] Id 2 +Iq 2 ≤Ismax 2 (9);

[0086] According to the above formula (9), we can construct Figure 4 and Figure 5 Similarly, according to different Id and Iq values, the current limit circle can be constructed as follows: Figure 5 Different equal current circles in the.

[0087] S2C: constructing the target query table of the correspondence between torque and current based on the maximum torque curve, the equal torque curve and the equal current circle.

[0088] Specifically, the above steps have constructed and processed the maximum torque curve, the equal torque curve and the equal current circle, so the above curves can be projected into the same coordinate system, and the corresponding relationship between current and torque can be obtained, thereby constructing a target query table.

[0089] See also Figure 6 , Figure 6 A specific implementation of step S2 is shown, which is described in detail as follows:

[0090] S21: Obtaining a target torque curve of the power generation torque in the target lookup table.

[0091] S22: Obtain the target torque curve, the position point where the maximum torque curve intersects with the equal current circle in the query 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 the embodiment of the present application, the motor controller obtains the target torque curve of the generating torque in the target query table, obtains the position point where the target torque curve, the maximum torque curve and the equal current circle intersect in the query table, and obtains the target direct-axis current and the target quadrature-axis current of the permanent magnet synchronous motor corresponding to the position point. In a specific embodiment, Figure 5 As shown, if the generating torque is T2, the equal torque curve can be obtained, and the position point where it intersects with the maximum torque curve and the equal current circle can be obtained, that is, Figure 6 At point B in the figure, the direct-axis current and the quadrature-axis current of the permanent magnet synchronous motor at point B are obtained and used as the target direct-axis current and the 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 the battery system.

[0094] See also Figure 7 and Figure 8 , Figure 7 A specific implementation of step S3 is shown. Figure 8 The control block diagram of the motor controller provided in the embodiment of the present application is described in detail as follows:

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

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

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

[0098]

[0099]

[0100] Among them, 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 electrical 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 the embodiment of the present application, the target direct-axis current and the target quadrature-axis current are transmitted to the current loop to calculate the direct-axis voltage and the quadrature-axis voltage of the permanent magnet synchronous motor. The direct-axis voltage and the 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: transmitting the direct-axis voltage and the quadrature-axis voltage to space vector pulse width modulation for energy conversion, distributing the converted energy to the motor, and feeding back the converted energy to the battery system through the current loop after coordinate conversion.

[0103] In the embodiment of the present application, the direct-axis voltage and the quadrature-axis voltage are transmitted to the space vector pulse width modulation SVPWM 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 conversion. Among them, the main idea of ​​SVPWM is to use the ideal flux linkage circle of the stator of the three-phase symmetrical motor when the three-phase symmetrical sine wave voltage is powered as a reference standard, and to make appropriate switching with different switching modes of the three-phase inverter to form a PWM wave, and to track its accurate flux linkage circle with the actual flux linkage vector formed.

[0104] S4: When the voltage in the battery 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 query 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.

[0105] In an embodiment of the present application, if the voltage in the battery exceeds a preset value, that is, when the battery SOC is too high, the battery does not allow a large amount of recovered energy. At this time, it is necessary to re-acquire 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 power generation efficiency and the power generation current, so as to reduce the charging energy in the battery system, convert the braking energy into motor heat energy for consumption, reduce the charging of high SOC batteries, and reduce the wear of mechanical brakes.

[0106] See also Fig. 9 , Fig. 9 A specific implementation of step S4 is shown, which is described in detail as follows:

[0107] S41: When the voltage in the battery exceeds a preset value, the vehicle domain controller is used to request braking to transmit the power generation torque to the motor controller.

[0108] S42: traverse the target query table through the motor controller to obtain the target position point where the equal torque curve corresponding to the power generation torque intersects only with the equal current circle, and obtain 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, the above formulas (6) and (7) can calculate the maximum output voltage and voltage constraints, so it can be judged whether the voltage in the battery exceeds the preset value based on this. When it exceeds the preset value, the vehicle domain controller requests the braking power generation torque to be transmitted to the motor controller, and the motor controller traverses the target query table to obtain the target position point where the equal torque curve corresponding to the power generation torque only intersects with the equal current circle, and obtains the new target direct axis current and new target quadrature axis current corresponding to the target position point. Figure 5 As shown, the target position point is point C, and the power generation efficiency of this point is lower than that of point B, so the new target direct-axis current and the new target quadrature-axis current corresponding to point C are redistributed, thereby reducing the power generation efficiency of the system, converting the braking energy into motor heating energy for consumption, reducing the charging of high SOC batteries, and reducing the wear of mechanical brakes. It should be noted that the distribution process of the new target direct-axis current and the new target quadrature-axis current is the same as the above-mentioned steps S31 and S32, and will not be repeated here to avoid repetition.

[0111] In the embodiment of the present application, when the brake pedal is triggered, the braking power generation torque is requested to be transmitted to the motor controller through the vehicle domain controller; based on the power generation torque, the target query table is traversed to obtain the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor; 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; when the voltage in the battery exceeds the 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 query 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 the embodiment of the present invention, when the electric vehicle encounters special road conditions such as a long downhill slope, and when the battery voltage is very high, it is not allowed to generate a lot of feedback energy. The motor current distribution can be used to reduce the power generation efficiency, thereby converting the braking force into heat for consumption, thereby reducing energy recovery and mechanical brake wear.

[0112] Please refer to Fig.10 , as a response to the above Figure 1 The present application provides an embodiment of a system for implementing an electric retarder. Figure 1 Corresponding to the method embodiment shown, the system can be specifically applied to various automobiles.

[0113] like Fig.10 As shown, the implementation system of the electric retarder of 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 braking power generation torque to be transmitted to the motor controller through the vehicle domain controller when the brake pedal is triggered;

[0115] A target current acquisition unit 52, configured to traverse a target lookup table based on the power generation torque to acquire a target direct-axis current and a target quadrature-axis current of the permanent magnet synchronous motor;

[0116] an energy conversion unit 53, configured to perform energy conversion between the target direct-axis current and the target quadrature-axis current based on the motor controller, and distribute the converted energy to the motor and the 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 query table when the voltage in the battery exceeds a preset value, and 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, used for transmitting the target direct-axis current and the target quadrature-axis current to a current loop in the motor controller to calculate the direct-axis voltage and the quadrature-axis voltage of the permanent magnet synchronous motor;

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

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

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

[0123]

[0124]

[0125] Among them, 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 electrical 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 further includes:

[0127] A curve construction unit, used for constructing a maximum torque curve and an equal torque curve based on a torque equation of an embedded permanent magnet synchronous motor;

[0128] An equal current circle construction unit, used for constructing an equal current circle based on a voltage equation of a permanent magnet synchronous motor in a steady state;

[0129] A target query table construction unit is used to construct the target query table of the corresponding relationship between torque and current based on the maximum torque curve, the equal torque curve and the equal current circle.

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

[0131] A target torque curve acquisition unit, used to acquire a target torque curve of the power generation torque in the target query table;

[0132] A current acquisition unit is used to obtain the target torque curve, the position point where the maximum torque curve intersects the equal current circle in the query 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] Further, the current redistribution unit 54 includes:

[0134] A braking request unit, used for requesting braking to transmit the power generation torque to the motor controller through the vehicle domain controller when the voltage in the battery exceeds a preset value;

[0135] a target position point acquisition unit, configured to traverse the target query table through the motor controller to acquire a target position point where the equal torque curve corresponding to the power generation torque intersects only with the equal current circle, and to acquire the new target direct-axis current and the new target quadrature-axis current corresponding to the target position point;

[0136] A 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 the steady state is:

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

[0139] Uq=Rs*Iq-Ld*Id*We+Ψf*We;

[0140] Among them, 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 electrical 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:

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

[0143]

[0144] Among them, Te is the electromagnetic torque, Np is the number of motor pole pairs, Ψf is the permanent magnet flux 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 the embodiment of the present application, when the brake pedal is triggered, the braking power generation torque is requested to be transmitted to the motor controller through the vehicle domain controller; based on the power generation torque, the target query table is traversed to obtain the target direct-axis current and target quadrature-axis current of the permanent magnet synchronous motor; 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; when the voltage in the battery exceeds the 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 query 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 the embodiment of the present invention, when the electric vehicle encounters special road conditions such as a long downhill slope, and when the battery voltage is very high, it is not allowed to generate a lot of feedback energy. The motor current distribution can be used to reduce the power generation efficiency, thereby converting the braking force into heat for consumption, thereby reducing energy recovery and mechanical brake wear.

[0146] Obviously, the embodiments described above are only some embodiments of the present application, rather than all embodiments. The preferred embodiments of the present application are given in the accompanying drawings, but they do not limit the patent scope of the present application. The present application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. Although the present application is described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific implementation methods, or to perform equivalent replacement of some of the technical features therein. Any equivalent structure made using the contents of the specification and drawings of this application, directly or indirectly used in other related technical fields, is 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 brake power generation torque to be transmitted to the motor controller; Traversing the target lookup table based on the power generation torque to obtain a target direct-axis current and a target quadrature-axis current of the permanent magnet synchronous motor; 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 the battery system; When the voltage in the battery 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 query 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.

2. The method for implementing the electric retarder according to claim 1, characterized in that: The method 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 the battery system includes: In the motor controller, the target direct-axis current and the target quadrature-axis current are transmitted to a current loop to calculate the direct-axis voltage and the 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 conversion.

3. The method for implementing the electric retarder according to claim 2, characterized in that: Calculating the direct-axis voltage and quadrature-axis voltage of the permanent-magnet synchronous motor by using the voltage equation of the embedded permanent-magnet synchronous motor; The voltage equation of the embedded permanent magnet synchronous motor is: Among them, 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 electrical 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 an electric retarder according to any one of claims 1 to 3, characterized in that: Before traversing the target lookup table based on the generated torque to acquire the target direct-axis current and the target quadrature-axis current of the permanent magnet synchronous motor, the method includes: Construct the maximum torque curve and equal torque curve based on the torque equation of the embedded permanent magnet synchronous motor; Construct equal current circles based on the voltage equation of the permanent magnet synchronous motor in steady state; The target query table of the correspondence between torque and current is constructed based on the maximum torque curve, the equal torque curve and the equal current circle.

5. The method for implementing the electric retarder according to claim 4, characterized in that: The step of traversing 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 includes: Acquire a target torque curve of the power generation torque in the target query table; The target torque curve, the position point where the maximum torque curve intersects with the equal current circle are obtained in the query table, and the target direct-axis current and the target quadrature-axis current of the permanent magnet synchronous motor corresponding to the position point are obtained.

6. The method for implementing the electric retarder according to claim 4, characterized in that: When the voltage in the battery 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 query 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, including: When the voltage in the battery exceeds a preset value, the vehicle domain controller is used to request braking to transmit the power generation torque to the motor controller; Traversing the target query table through the motor controller to obtain a target position point where the equal torque curve corresponding to the power generation torque intersects only with the equal current circle, and obtaining the new target direct-axis current and the new target quadrature-axis current corresponding to the target position point; 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.

7. The method for implementing the electric retarder according to claim 4, characterized in that: The voltage equation of the permanent magnet synchronous motor in the steady state is: Ud=Rs*Id-Lq*Iq*We; Uq=Rs*Iq-Ld*Id*We+Ψf*We; Among them, 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 electrical 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.

8. The method for implementing the electric retarder according to claim 4, characterized in that: The torque equation of the embedded permanent magnet synchronous motor is: Te=1.5*Np*(Ψf*Iq+(Ld-Lq)*Id*Iq); Among them, Te is the electromagnetic torque, Np is the number of motor pole pairs, Ψf is the permanent magnet flux 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.

9. A system for implementing an electric retarder, characterized in that: include: The power generation torque transmission unit is used to request the braking power generation torque to be transmitted to the motor controller through the vehicle domain controller when the brake pedal is triggered; A target current acquisition unit, configured to traverse a target query table based on the power generation torque to acquire a target direct-axis current and a target quadrature-axis current of the permanent magnet synchronous motor; an energy conversion unit, configured to perform energy conversion on the target direct-axis current and the target quadrature-axis current based on the motor controller, and distribute the converted energy to the motor and a 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 query 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.

10. The implementation system of the electric retarder according to claim 9, characterized in that: The energy conversion unit comprises: A voltage calculation unit, used for transmitting the target direct-axis current and the target quadrature-axis current to a current loop in the motor controller to calculate the direct-axis voltage and the quadrature-axis voltage of the permanent magnet synchronous motor; The energy distribution unit is used to transmit the direct-axis voltage and the quadrature-axis voltage to the space vector pulse width modulation for energy conversion, distribute the converted energy to the motor, and feed back the converted energy to the battery system through the current loop after coordinate conversion.

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