Motor torque control method and system for limiting energy recovery power

Abstract

The present invention provides a motor torque control method and system for limiting energy recovery power. First, the battery management module monitors and sends the battery pack voltage, current and maximum charging power to the VCU. If the VCU detects that the maximum charging power is lower than the preset value, it sends a flag 1 instruction to allow limited feedback power, a torque request and maximum feedback power parameters to the MCU; otherwise, it sends a flag 0 instruction. In the flag 0 state, the MCU looks up the table MAP1 to generate a conventional current instruction to drive the motor; in the flag 1 state, the active limited feedback mode is enabled, and MAP2 is called to generate a current control instruction to reduce the energy recovery efficiency and simultaneously maintain the feedback torque output. Without increasing the product cost and on the premise of borrowing existing hardware resources, the present invention controls the motor to limit the energy recovery power when outputting negative torque through the upgrade of the software algorithm, effectively 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.

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] Currently, new energy vehicles require the drive motor system to output negative torque during braking and maximum speed regulation. However, the feedback power generated by negative torque can overcharge the battery pack, which has a certain impact on the health and life of the battery. Therefore, when the power battery is close to SOC saturation (SOC greater than 90%), the drive motor system will not be allowed to generate negative torque, which means that coasting feedback and braking energy recovery are not possible.

[0003] Existing technologies use motors to actively reduce efficiency to generate heat (for low-temperature heating), but their application is limited to thermal management and does not address the conflict between energy recovery and battery protection at high SOCs. A motor torque control method that limits regenerative power is urgently needed. This method, when controlling the motor to output negative torque, limits regenerative power, thereby ensuring braking performance near SOC saturation and the ability to control the vehicle's maximum speed on long downhill slopes. Summary of the Invention

[0004] In response to 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 leveraging existing hardware resources, the method and system control the motor to limit the energy recovery power when outputting negative torque only through software algorithm upgrades, effectively ensuring the vehicle's braking performance in a state 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, a motor torque control method for limiting energy recovery power is provided, 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 5 kW, a command is sent to the motor controller MCU, indicating that the limit feedback power flag is set to 1 and the maximum feedback power allowed. 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 5 kW, a command is sent to the motor controller MCU, which sets the flag for limiting the regenerative power to 0, and simultaneously sends the original torque request and the maximum regenerative power allowed;

[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 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 feedback power is 1, the motor controller determines that it is necessary to actively limit the feedback power and uses the preset table MAP2 to generate I d / I q The current command drives the motor to reduce the energy recovery efficiency of the motor, and feeds back the motor speed, the allowed limited feedback power flag 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 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 while maintaining the feedback torque consistent with the feedback torque under MAP1 control compared to MAP1.

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

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

[0017]

[0018] Among them, Tmax_regen is the maximum feedback torque (unit: N·m), P limit is the maximum allowable feedback 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) is configured to generate a flag for allowing a limited regenerative power, a torque request, and an allowable maximum regenerative power based on 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 based on the allowed limited feedback power flag 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 interfaces 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] Energy distribution module, used to distribute feedback power to the battery pack or 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, it controls the motor to limit the energy recovery power when outputting negative torque only by upgrading the software algorithm, 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 upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

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

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

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein 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 sought, 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 this field without making any creative efforts are within the scope of protection of the present application. Furthermore, descriptions of "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 including a battery management module (BMS), a motor, a motor control unit (MCU) and a vehicle controller unit (VCU), wherein the vehicle controller (VCU) is used to control the maximum charging power of the battery pack when the maximum charging power P max_chargeWhen the charge power falls below a preset calibration value, the motor is controlled to reduce the efficiency of converting kinetic energy into electrical energy without reducing the motor's regenerative torque, thereby converting part of the kinetic energy into heat energy, thereby reducing the charging power and maintaining a certain allowable charging power for the battery pack. This further reduces the impact of the charging power on the motor's regenerative torque capability, ensuring the vehicle's braking performance when approaching SOC saturation (SOC greater than 90%) and the vehicle's maximum speed control capability in long downhill scenarios. 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 voltage V (unit: V) of the battery pack, the total current I (unit: A) of the battery pack, and the 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] ①Send the flag 1 of allowing limited feedback power to the motor controller MCU;

[0042] ②Calculate 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 shock to the motor or mechanical system caused by sudden torque changes. Send the 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 and the normal mode is maintained. 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 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 using the following formula:

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

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

[0051] Step S3: The motor controller MCU receives the allowed limited feedback power flag (1 / 0) and torque request T from the vehicle controller VCU. request Or Torque_R and maximum allowed 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 based on 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 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 feedback 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 feedback power is 1, the motor controller MCU determines that it is necessary to actively limit the feedback power. The motor controller uses the preset table MAP2 to generate I d / I q Current command, reduces the energy recovery efficiency of the motor, but keeps the motor feedback torque consistent with MAP1, and feeds back the motor speed n (unit: rpm), allowing the feedback power flag bit 1 and the 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 allocate the heat generated by the motor's reduced efficiency to battery pack heating or cabin heating. Specifically, according to the selected MAP table, Trq Stew converts to I d_ref with I q_ref , where: MAP2 I q The command is the same as MAP1 to ensure the same torque, but I d The command is remapped to inject demagnetizing current or adjust the flux linkage, increasing the internal loss of the motor. Output I 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 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 compared to MAP1 and 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 feedback 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 found 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 brake 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 based on the allowed limited feedback power flag 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 interfaces and control logic of the BMS, VCU, and MCU to achieve multi-module collaborative decision-making. The power domain controller further includes:

[0065] Energy distribution module, used to distribute feedback power to the battery pack or 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 5 kW, a command is sent to the motor controller MCU, indicating that the limit feedback power flag is set to 1 and the maximum feedback power allowed. 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 5 kW, a command is sent to the motor controller MCU, which sets the flag for limiting the regenerative power to 0, and simultaneously sends the original torque request and the maximum regenerative power allowed; 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; 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 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 feedback power is 1, the motor controller determines that it is necessary to actively limit the feedback power and uses the preset table MAP2 to generate I d / I q The current command drives the motor to reduce the energy recovery efficiency of the motor, and feeds back the motor speed, the allowed limited regenerative power flag 1, and the maximum regenerative torque to the vehicle controller VCU, thereby reducing the energy recovery efficiency of the motor while maintaining the motor regenerative torque. At the same time, the motor controller MCU is linked with the vehicle thermal management system to use the heat generated by the motor's reduced energy recovery efficiency for battery pack or cabin heating; The maximum regenerative torque is calculated by the following formula: in, 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; The preset lookup tables MAP1 and MAP2 are two-dimensional mapping tables based on motor speed and torque request, and the corresponding values ​​under the same motor speed and torque request in the preset lookup table MAP2 are I 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.

2. 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.

3. 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.

4. A motor torque control system for limiting energy recovery power, characterized in that: A motor torque control method for implementing the energy recovery power limitation method according to any one of claims 1 to 3, comprising: 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) is configured to generate a flag for allowing a limited regenerative power, a torque request, and an allowable maximum regenerative power based on 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 based on the allowed limited feedback power flag 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 interfaces and control logic of the BMS, VCU, and MCU to achieve multi-module collaborative decision-making.

5. The motor torque control system for limiting energy recovery power according to claim 4, characterized in that: The power domain controller further comprises: Energy distribution module, used to distribute feedback power to the battery pack or 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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