Motor torque control method and system for limiting energy recovery power

Abstract

The invention provides a motor torque control method and system for limiting energy recovery power. Firstly, a battery management module monitors and sends the voltage, current and maximum charging power of a battery pack to a VCU; if the VCU detects that the maximum charging power is lower than a preset value, the VCU sends a permission limit feedback power flag 1 instruction, a torque request and a maximum feedback power parameter to the MCU; otherwise, sending a mark 0 instruction. The MCU looks up a table MAP1 under the state of marking 0 to generate a conventional current instruction to drive a motor; and an active limited feedback mode is started in the state of the mark 1, an MAP2 is called to generate a current control instruction to reduce the energy recovery efficiency, and feedback torque output is synchronously maintained. On the premise that product cost is not increased and existing hardware resources are borrowed, the energy recovery power is limited under the condition that a software algorithm is upgraded and the motor is controlled to output negative torque, and the braking performance of the vehicle when the vehicle is close to SOC saturation and the maximum vehicle speed control capacity of the vehicle in a long downhill scene are effectively guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of automobile intelligent control, and in particular to a motor torque control method and system for limiting energy recovery power. Background Art

[0002] At present, new energy vehicles require the drive motor system to output negative torque during the braking process and the maximum speed adjustment limit. However, the feedback electric power generated by the negative torque will cause the battery pack to overcharge, which will have a certain impact on the health and life of the battery. Therefore, the power battery will not allow the drive motor system to generate negative torque when it is close to SOC saturation (SOC greater than 90%), that is, coasting feedback and braking energy recovery cannot be performed.

[0003] There are technical solutions in the prior art that generate heat (for low-temperature heating) by actively reducing the efficiency of the motor, but its application scenario is limited to thermal management, and the contradiction between energy recovery and battery protection under high SOC is not resolved. There is an urgent need for a motor torque control method that limits the energy recovery power, which controls the motor to limit the energy recovery power when outputting negative torque, thereby ensuring the braking performance of the vehicle when it is close to SOC saturation and the maximum speed control capability of the vehicle in long downhill scenarios. Summary of the invention

[0004] In view of the defects in the prior art, the purpose of the present invention is to provide a motor torque control method and system for limiting energy recovery power. Without increasing product costs and under the premise of borrowing existing hardware resources, only by upgrading the software algorithm, the motor is controlled to limit the energy recovery power when outputting negative torque, thereby effectively ensuring the braking performance of the vehicle when it is close to SOC saturation (SOC greater than 90%) and the vehicle's maximum speed control capability in long downhill scenarios.

[0005] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0006] According to a first aspect of the present invention, there is provided a motor torque control method for limiting energy recovery power, comprising the following steps:

[0007] Step S1: The battery management module BMS obtains the total voltage, total current and maximum charging power of the battery pack in real time, and transmits the above parameters to the vehicle controller VCU;

[0008] Step S2: The vehicle controller VCU performs the following logical judgment based on the received parameters:

[0009] If the maximum charging power is lower than 5kw, an instruction to allow the limited feedback power flag to be 1 and the maximum feedback power to be allowed is sent to the motor controller MCU; at the same time, the slope of the original torque request is adjusted to generate a smooth torque request and send it to the MCU;

[0010] If the maximum charging power is not less than 5kw, an instruction to allow the limited feedback power flag to be 0 is sent to the motor controller MCU, and the original torque request and the maximum allowed feedback power are sent simultaneously;

[0011] Step S3: The motor controller MCU adopts the following corresponding current control strategy according to the allowed limited feedback power flag:

[0012] When the flag for limiting the feedback power is 0, the motor controller determines that it is not necessary to actively limit the feedback power, and uses the preset table MAP1 to generate I d / I q Current command drives the motor to run and feeds back the motor speed, allowing the limited feedback power mark 0 and the maximum feedback torque to the vehicle controller VCU;

[0013] When the flag for limiting the feedback power is 1, the motor controller determines that active feedback power limitation is required and generates I d / I q The current instruction drives the motor to run, which is used to reduce the energy recovery efficiency of the motor, and feeds back the motor speed, the allowed limited feedback power mark 1 and the maximum feedback torque to the vehicle controller VCU, thereby reducing the energy recovery efficiency of the motor while maintaining the motor feedback torque. At the same time, the motor controller MCU is linked with the on-board thermal management system to use the heat generated by the motor's operation with reduced energy recovery efficiency for battery pack or cabin heating.

[0014] Optionally, the preset lookup tables MAP1 and MAP2 are two-dimensional mapping tables based on motor speed and torque request, and the I corresponding to the same motor speed and torque request in the preset lookup table MAP2 is d / I q The current value is configured to reduce the motor energy recovery efficiency while maintaining the feedback torque consistent with the feedback torque under MAP1 control compared to MAP1.

[0015] Optionally, in step S2, the maximum allowable recharge power is calculated according to the following formula: maximum allowable recharge power = maximum charging power of the battery pack + real-time power of the high-voltage accessories.

[0016] Optionally, the maximum feedback torque is calculated by the following formula:

[0017]

[0018] Among them, Tmax_regen is the maximum feedback torque (unit: N·m), P limit is the maximum allowable regenerative power (unit: kW); η motor is the motor system efficiency, n is the motor speed (unit: rpm); η motor The motor system efficiency can be obtained by looking up the table in the motor controller MCU based on the motor speed, required torque and voltage.

[0019] Optionally, before the motor controller MCU adopts the following corresponding current control strategy according to the allowed limited feedback power flag in step S3, it is necessary to perform secondary filtering and validity verification on the received original torque request or the torque request after slope adjustment.

[0020] Optionally, the method further includes step S4: after the vehicle controller VCU receives the maximum allowable feedback power and maximum feedback torque, it dynamically adjusts the compensation torque of the vehicle mechanical braking system to match the total braking force with the driver's demand.

[0021] According to a second aspect of the present invention, a motor torque control system for limiting energy recovery power is provided, which is used to implement the above-mentioned motor torque control method for limiting energy recovery power, comprising:

[0022] Battery management module BMS, used to monitor and transmit the total voltage, total current and maximum charging power of the battery pack in real time;

[0023] A vehicle controller VCU, configured to generate a flag for allowing limited regenerative power, a torque request and an allowable maximum regenerative power according to a comparison result between the maximum charging power and a preset calibration value;

[0024] The motor controller MCU is used to switch the preset lookup table MAP1 or MAP2 to execute the corresponding I d / I q Current control, and when the limited feedback power flag is set to 1, the power conversion efficiency is reduced while maintaining the motor feedback torque;

[0025] The power domain controller is used to integrate the communication interface and control logic of the BMS, VCU, and MCU to achieve multi-module collaborative decision-making.

[0026] Optionally, the power domain controller further includes:

[0027] An energy distribution module is used to distribute the feedback electric energy to the battery pack or the thermal energy conversion path according to the battery status;

[0028] The torque compensation module is used to generate a mechanical brake compensation instruction when the allowed limited feedback power flag is 1.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The advantage of the present invention is that it does not increase product costs and, under the premise of borrowing existing hardware resources, only by upgrading the software algorithm, it controls the motor to limit the energy recovery power when outputting negative torque, thereby effectively ensuring the braking performance of the vehicle when it is close to SOC saturation and the vehicle's maximum speed control capability in long downhill scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0032] Figure 1 is a flowchart of the steps of the motor torque control method for limiting energy recovery power described in the first embodiment;

[0033] Figure 2 It is a flow chart of the motor torque control method for limiting energy recovery power described in the first embodiment; DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is claimed, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative efforts are within the scope of protection of the present application. Furthermore, the descriptions involving "first", "second", etc. in the application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0036] First Embodiment

[0037] like Figure 1 , Figure 2 As shown, this embodiment provides a motor torque control method for limiting energy recovery power, which is applied to a motor active energy recovery control device, the device comprising a battery management module (BMS), a motor, a motor control unit (MCU) and a vehicle controller (VCU), wherein the vehicle controller (VCU) is used to control the maximum charging power P of the battery pack. max_chargeWhen the speed is lower than a preset calibration value, the motor is controlled to convert part of the kinetic energy into heat energy by reducing the efficiency of converting the kinetic energy into electrical energy without reducing the motor feedback torque, thereby reducing the charging power, so that the battery pack maintains a certain allowable charging power, and then reducing the impact of the charging power on the motor feedback torque capacity, thereby ensuring the braking performance of the vehicle when it is close to SOC saturation (SOC greater than 90%) and the maximum speed control ability of the vehicle in a long downhill scene. The method includes:

[0038] Step S1: The battery management module BMS transmits the total voltage V (unit: V), the total current I (unit: A) and the current maximum charging power P of the battery pack through the CAN bus. max_charge (Unit: kw) is sent to the vehicle controller VCU.

[0039] Step S2: The vehicle controller VCU receives the total battery pack voltage V (unit: V), the total battery pack current I (unit: A) and the current maximum charging power P of the battery pack. max_charge Make the following logical judgment:

[0040] (1) When the battery pack has the maximum charging power P max_charge When the power is less than the preset calibration value (5kw in this embodiment), the active limited feedback mode is triggered, and the vehicle controller VCU performs the following operations:

[0041] ① Send the flag bit 1 for allowing limited feedback power to the motor controller MCU;

[0042] ② Calculate the maximum allowable feedback power P limit (Unit: kw);

[0043] ③ Original torque request T request Perform slope adjustment (torque command change rate adjustment) to generate a smooth torque command Torque_R. By dynamically adjusting the torque slope, the smoothness of the torque output is ensured to avoid shocks to the motor or mechanical system caused by sudden torque changes. Send flag bit = 1, Torque_R and P to the MCU limit . .

[0044] (2) If the maximum charging power of the battery pack is P max_charge When the power is greater than or equal to the preset calibration value (5kw in this embodiment), the active limited feedback mode is not triggered, the normal mode is maintained, and the vehicle controller VCU performs the following operations:

[0045] ① Send the flag bit 0 for allowing limited feedback power to the motor control MCU;

[0046] ②Send the original torque request T request (Unit: N·m) (without slope adjustment);

[0047] ③Calculate the maximum allowable feedback power P limit (Unit: kw).

[0048] Among them, the maximum feedback power allowed is P limit Calculated according to the following formula:

[0049] P limit =P max_charge +P accessory ;

[0050] Among them, P accessory It is the real-time power of high-voltage accessories (unit: kw). High-voltage accessories include compressor, car heater PTC, DCDC converter. The real-time power of high-voltage accessories can be obtained by receiving the input voltage and current of high-voltage accessories through CAN signals.

[0051] Step S3: The motor controller MCU receives the flag bit (1 / 0) and torque request T sent by the vehicle controller VCU. request or Torque_R and maximum allowable regenerative power P limit , first of all, T request Or Torque_R performs secondary filtering and validity verification, and calculates the real-time torque demand Trq in combination with the motor speed n Stew. At the same time, different current control strategies are adopted according to different allowed limited feedback power flags:

[0052] (1) If the flag bit for limiting the feedback power is 0, the motor controller MCU determines that it is not necessary to actively limit the feedback power and maintains the normal mode. The motor controller MCU uses the preset table MAP1 to generate I d / I q Current command, drives the motor to run and feeds back the motor speed n (unit: rpm), allows limited feedback power flag 0 and maximum feedback torque T max_regen (Unit: N·m) to the vehicle controller VCU;

[0053] (2) If the flag bit for limiting the feedback power is 1, the motor controller MCU determines that active feedback power limitation is required, and the motor controller uses the preset table MAP2 to generate I d / I q Current command, reduce the energy recovery efficiency of the motor, but keep the motor feedback torque consistent with MAP1, and feedback the motor speed n (unit: rpm), allow limited feedback power flag 1 and maximum feedback torque T max_regen(Unit: N·m) to the vehicle controller VCU, maintaining the motor feedback torque by reducing the power conversion efficiency. At the same time, the motor controller MCU works in conjunction with the vehicle thermal management system to distribute the heat generated by the motor's reduced efficiency to the battery pack heating or cabin heating. Specifically, according to the selected MAP table, Trq Stew to I d_ref with I q_ref , where: MAP2 I q The command is the same as MAP1 to ensure consistent torque, but I d The command is remapped to inject demagnetization current or adjust the flux linkage, increasing the internal losses of the motor. d_ref ,I q_ref The current loop is executed and the thermal management system is linked to distribute the lost heat to battery heating or cabin heating.

[0054] The preset lookup tables MAP1 and MAP2 are two-dimensional mapping tables based on motor speed and torque request, and the corresponding I values ​​under the same motor speed and torque request in the preset lookup table MAP2 are d / I q The current value is configured to reduce the motor energy recovery efficiency compared to MAP1, and to maintain the motor feedback torque consistent with the feedback torque under MAP1 control.

[0055] Among them, the maximum feedback torque T max_regen Calculated by the following formula:

[0056]

[0057] Among them, P limit is the maximum allowable regenerative power (unit: kW); η motor is the motor system efficiency, n is the motor speed (unit: rpm), η motor The efficiency of the motor system can be obtained by looking up the table in the motor controller based on the speed, torque and voltage.

[0058] Step S4: The vehicle controller (VCU) dynamically adjusts the compensation torque of the mechanical braking system according to the received allowed limited feedback power flag and the maximum feedback torque, so that the total braking force matches the driver's demand.

[0059] Second Embodiment

[0060] This embodiment provides a motor torque control system for limiting energy recovery power, which is used to implement the motor torque control method for limiting energy recovery power described in the first embodiment, and includes the following parts:

[0061] Battery management module (BMS), used to monitor and transmit the total voltage, total current and maximum charging power of the battery pack in real time;

[0062] The vehicle controller (VCU) is used to generate the allowed limited feedback power flag and torque request T according to the comparison result of the maximum charging power of the battery pack and the preset calibration value. request and the maximum allowable feedback power P limit ;

[0063] The motor controller MCU is used to switch the preset lookup table MAP1 or MAP2 to execute the corresponding I d / I q Current control, and when the limited feedback power flag is set to 1, the power conversion efficiency is reduced while maintaining the motor feedback torque;

[0064] The power domain controller integrates the communication interface and control logic of the BMS, VCU, and MCU to achieve multi-module collaborative decision-making. The power domain controller further includes:

[0065] An energy distribution module is used to distribute the feedback electric energy to the battery pack or the thermal energy conversion path according to the battery status;

[0066] The torque compensation module is used to generate mechanical brake compensation instructions in the active limited feedback mode.

Claims

1. A motor torque control method for limiting energy recovery power, characterized in that: The following steps are involved: Step S1: The battery management module BMS obtains the total voltage, total current and maximum charging power of the battery pack in real time, and transmits the above parameters to the vehicle controller VCU; Step S2: The vehicle controller VCU performs the following logical judgment based on the received parameters: If the maximum charging power is lower than 5kw, an instruction to allow the limited feedback power flag to be 1 and the maximum feedback power to be allowed is sent to the motor controller MCU; at the same time, the slope of the original torque request is adjusted to generate a smooth torque request and send it to the MCU; If the maximum charging power is not less than 5kw, an instruction to allow the limited feedback power flag to be 0 is sent to the motor controller MCU, and the original torque request and the maximum allowed feedback power are sent simultaneously; Step S3: The motor controller MCU adopts the following corresponding current control strategy according to the allowed limited feedback power flag: When the flag for limiting the feedback power is 0, the motor controller determines that it is not necessary to actively limit the feedback power, and uses the preset table MAP1 to generate I d / I q Current command drives the motor to run and feeds back the motor speed, allowing the limited feedback power mark 0 and the maximum feedback torque to the vehicle controller VCU; When the flag for limiting the feedback power is 1, the motor controller determines that active feedback power limitation is required and generates I d / I q The current instruction drives the motor to run, which is used to reduce the energy recovery efficiency of the motor, and feeds back the motor speed, the allowed limited feedback power mark 1 and the maximum feedback torque to the vehicle controller VCU, thereby reducing the energy recovery efficiency of the motor while maintaining the motor feedback torque. At the same time, the motor controller MCU is linked with the on-board thermal management system to use the heat generated by the motor's operation with reduced energy recovery efficiency for battery pack or cabin heating.

2. The motor torque control method for limiting energy recovery power according to claim 1, characterized in that: The preset lookup tables MAP1 and MAP2 are two-dimensional mapping tables based on motor speed and torque request, and the I corresponding to the same motor speed and torque request in the preset lookup table MAP2 is d / I q The current value is configured to reduce the motor energy recovery efficiency while maintaining the feedback torque consistent with the feedback torque under MAP1 control compared to MAP1.

3. The motor torque control method for limiting energy recovery power according to claim 1, characterized in that: In step S2, the maximum allowable regenerative power is calculated according to the following formula: maximum allowable regenerative power = maximum charging power of battery pack + real-time power of high-voltage accessories.

4. The motor torque control method for limiting energy recovery power according to claim 1, characterized in that: The maximum regenerative torque is calculated by the following formula: Among them, T max_regen is the maximum feedback torque (unit: N·m), P limit is the maximum allowable regenerative power (unit: kW); η motor is the motor system efficiency, n is the motor speed (unit: rpm); η motor The motor system efficiency can be obtained by looking up the table in the motor controller MCU based on the motor speed, required torque and voltage.

5. The motor torque control method for limiting energy recovery power according to claim 1, characterized in that: Before the motor controller MCU adopts the following corresponding current control strategy according to the flag bit of the allowed limited feedback power in step S3, it is necessary to perform secondary filtering and validity verification on the received original torque request or the torque request after slope adjustment.

6. The motor torque control method for limiting energy recovery power according to claim 1, characterized in that: The method further includes step S4: after receiving the maximum allowable feedback power and the maximum feedback torque, the vehicle controller VCU dynamically adjusts the compensation torque of the vehicle mechanical braking system to match the total braking force with the driver's demand.

7. A motor torque control system for limiting energy recovery power, characterized in that: The motor torque control method for implementing the energy recovery power limitation method according to any one of claims 1 to 6 comprises: Battery management module BMS, used to monitor and transmit the total voltage, total current and maximum charging power of the battery pack in real time; A vehicle controller VCU, configured to generate a flag for allowing limited regenerative power, a torque request and an allowable maximum regenerative power according to a comparison result between the maximum charging power and a preset calibration value; The motor controller MCU is used to switch the preset lookup table MAP1 or MAP2 to execute the corresponding I d / I q Current control, and when the limited feedback power flag is set to 1, the power conversion efficiency is reduced while maintaining the motor feedback torque; The power domain controller is used to integrate the communication interface and control logic of the BMS, VCU, and MCU to achieve multi-module collaborative decision-making.

8. The motor torque control system for limiting energy recovery power according to claim 7, characterized in that: The power domain controller further comprises: An energy distribution module is used to distribute the feedback electric energy to the battery pack or the thermal energy conversion path according to the battery status; The torque compensation module is used to generate a mechanical brake compensation instruction when the allowed limited feedback power flag is 1.

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