Demand torque estimation method based on power consumption and torque compensation

Abstract

The invention relates to a demand torque estimation method based on power consumption and torque compensation, and the method comprises the steps: carrying out the filtering processing of the opening degree of an accelerator pedal during the driving of a whole vehicle, carrying out the expected torque output of a driver intention and the recognition of a whole vehicle driving mode according to the current rotating speed of a motor, the filtered opening degree of the accelerator pedal, and the change rate parameter of the opening degree of the accelerator pedal; obtaining an initial torque; calculating battery consumption and battery over-current power following limitation according to the actual environment temperature and the battery residue, and estimating a limiting torque by a high-voltage accessory; the accelerator pedal opening degree, the accelerator pedal opening degree change rate and the vehicle speed serve as input, fuzzy processing is conducted, and then compensation torque is determined according to the formulated control rule; the minimum value of the limited torque, the compensation torque and the motor torque limit is taken as the required torque; and the required torque is accurately estimated, so that the power stability, the economical efficiency and the driving performance of the new energy automobile are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a method for estimating required torque based on power consumption and torque compensation. Background Art

[0002] With the continuous development of new energy vehicle technology, the requirements for vehicle power control systems are also increasing. Traditional demand torque estimation methods often cannot accurately reflect the actual state of the vehicle, resulting in reduced driving performance and energy waste. In the development process of pure electric vehicles, vehicle torque control is the core technology of the drive system. Accurately estimating the vehicle demand torque is the key to achieving efficient vehicle operation and a good driving experience. The power system of pure electric vehicles is different from that of traditional fuel vehicles. They are often driven by batteries and electric motors, and the performance and status of these components will be affected by various factors, such as battery temperature, remaining SOC, and the real-time working status of the motor. When the battery power is insufficient or the temperature is abnormal, the performance of the motor may be affected, resulting in insufficient or fluctuating torque output, affecting the vehicle's energy consumption, driving range, and the safety performance of the vehicle. In addition, during the start-up and acceleration of pure electric vehicles, the torque response of the motor is very fast. Since the output torque of the motor cannot be accurately controlled, the acceleration linearity of the vehicle may not be enough, resulting in sudden acceleration or a sense of frustration. This unstable power output not only reduces driving comfort, but also may cause wear and tear on vehicle components. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and to propose a method for estimating a required torque based on power consumption and torque compensation, and to dynamically adjust the required torque through torque compensation based on fuzzy control.

[0004] In order to solve the problems in the above background technology, the present invention is implemented by the following technical solutions: A method for estimating required torque based on power consumption and torque compensation, comprising: When the vehicle is driven, the sensors of each component monitor the vehicle's accelerator pedal opening Ped and vehicle speed in real time. ν The accelerator pedal opening rate Dped parameter is used to filter the accelerator pedal opening Ped. The expected torque output of the driver's intention and the vehicle driving mode are identified according to the current motor speed, the accelerator pedal opening rate Dped parameter and the filtered accelerator pedal opening Ped. The initial torque is calculated Tq ; Calculate battery consumption and battery overcurrent power following limit based on actual ambient temperature and battery remaining SOC, and estimate limit torque for high-voltage accessories Tlim ; The accelerator pedal opening Ped and the accelerator pedal opening change rate Dped, vehicle speed ν As input, after fuzzy processing, the compensation torque is determined according to the established control rules. Tini ; Take the limiting torque Tlim , Compensation torque Tini and motor torque limit Tmotmax The minimum value is taken as the required torque Tqdem .

[0005] Furthermore, the desired torque output intended by the driver is calibrated according to the current motor speed and the accelerator pedal opening Ped in different modes, and the driver's desired torque demand in the D gear is calculated by looking up a table; The vehicle mode recognition is to meet the driving conditions, specifically, the vehicle is driven in gear drive mode without brake pedal intervention; When the driving conditions are met, the initial torque is calculated Tq : Tq = Accped × Tmax ; in Accped is the accelerator pedal opening value in D gear driving mode, Tmax It is the maximum driving torque corresponding to the current speed of the motor.

[0006] Furthermore, the limiting torque Tlim for: ; ; Among them, the battery overcurrent coefficient is ß , n is the motor speed, Tmot is the real-time torque fed back by the motor, and the maximum allowable discharge power of the battery is Pbmax , the actual discharge power of the battery is Pbart , the actual battery voltage is Ubart, the maximum allowable pulse discharge current of the battery is Ibmax, and the real-time discharge current of the battery is Ibart, Pbmax - Pbart Battery overcurrent limit power, including power consumption of high-voltage accessories Paux , the power consumption of the vehicle high-voltage wiring harness Plin; The high-voltage accessories include a DCDC converter, an AC air-conditioning compressor, and a PCT heater; The torque limit imposed by the external ambient temperature and the battery SOC is realized by the maximum allowable pulse discharge current Ibmax of the battery. The torque is adjusted according to the difference between the real-time discharge current Ibart and the current maximum allowable pulse discharge current Ibmax of the battery, that is, according to the actual ambient temperature and the remaining SOC of the battery, the internal consumption of the battery, and the power consumption of the high-voltage accessories. Paux , the vehicle high voltage harness power consumption Plin, the limiting torque Tlim Make an estimate.

[0007] Furthermore, according to the actual vehicle speed at the initial torque Tq Based on the partial compensation torque Tcomp , used to increase power output to achieve the driver's driving intention under rapid acceleration and compensate for torque Tini for: Tini = Tq + Tcomp .

[0008] Furthermore, due to the excessive partial compensation torque Tcomp Will cause the vehicle to have impact and vibration. In order to ensure the comfort of the whole vehicle, it is necessary to Impact degree K Partial compensation torque Tcomp Limit the impact K The formula is: ; in, a is the acceleration, ν is vehicle speed, impact K Expressed as the rate of change of acceleration, da / dt , impact K If the vehicle speed is expressed as d 2 ν / dt 2 .

[0009] Furthermore, the compensation torque Tini Using fuzzy control algorithm, the accelerator pedal opening Ped, vehicle speed ν and the accelerator pedal opening rate Dped as input to compensate the torque Tini As output, a torque compensation fuzzy rule table is established; the accelerator pedal opening change rate Dped contains five fuzzy subsets: VS1, S1, M1, B1, VB1, and the domain is 0-100%; vehicle speed ν The variables include three fuzzy subsets: S2, M2, B2, and the domain is 0-120km / h; the accelerator pedal opening Ped includes three fuzzy subsets: S3, M3, B3, and the domain is 0-100%; the compensation torque TiniIt includes seven fuzzy subsets: ES, VS2, S4, M4, B4, VB2, EB, and the domain is 0-30Nm; Among them, ES is extremely small, VS1 and VS2 are relatively small, S1, S2, S3, and S4 are small, M1, M2, M3, and M4 are medium, B1, B2, B3, and B4 are large, VB1 and VB2 are relatively large, and EB is extremely large.

[0010] Furthermore, when the vehicle is starting or climbing a slope, the vehicle speed is in the smaller VS speed range. At this time, in order to obtain more power, it is necessary to increase the torque change under the same accelerator pedal opening Ped. By giving a larger VB or a maximum EB compensation torque Tini To meet the acceleration needs; When the vehicle is traveling in the suburbs or on national highways, the vehicle speed is in the medium M speed range, the vehicle acceleration demand is mostly for overtaking acceleration, and the torque change of the accelerator pedal opening Ped is moderate, then the compensation torque of S, M or B is increased. Tini ; When the vehicle is running at high speed, in order to maintain a large VB speed and keep it in the constant power range, the accelerator pedal opening change rate Dped and the torque change of the accelerator pedal opening Ped are small. At this time, the compensation torque of the small VS or extremely small ES is used to compensate. Tini .

[0011] Furthermore, the required torque Tqdem for: Tqdem = MIN ( Tmax , Tlim , Tini ); Required torque Tqdem After output ， When it is detected that the torque fluctuation of the drive motor exceeds the threshold, PID active damping control is performed to smooth the expected output torque of the drive motor to prevent shaking and thus improve the vehicle's driving stability.

[0012] Compared with the prior art, the present invention has the following beneficial technical effects: Taking into account the effects of different ambient temperatures and different SOC states of charge on the battery discharge current under actual working conditions, combined with the power consumption of the vehicle's high-voltage accessories, the required torque of the vehicle's motor is estimated; at the same time, in order to ensure the stability of the vehicle's power output, economic performance and driving experience, the accelerator pedal opening, the accelerator pedal opening change rate and the current vehicle speed are used as the input of fuzzy control, and the compensation torque is used as the output. A fuzzy control table is constructed to compensate the vehicle's power system with the actual required torque, and the required torque is accurately estimated to improve the power stability, economy and driving performance of new energy vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a framework diagram of the present invention; Figure 2 This is a diagram of the algorithm for compensating torque according to the present invention. DETAILED DESCRIPTION

[0014] like Figure 1 - Figure 2 As shown, a method for estimating required torque based on power consumption and torque compensation includes: When the vehicle is driven, the sensors of each component monitor the vehicle's accelerator pedal opening Ped and vehicle speed in real time. ν The accelerator pedal opening rate Dped parameter is used to filter the accelerator pedal opening Ped. The expected torque output of the driver's intention and the vehicle driving mode are identified according to the current motor speed, the accelerator pedal opening rate Dped parameter and the filtered accelerator pedal opening Ped. The initial torque is calculated Tq ; Calculate battery consumption and battery overcurrent power following limit based on actual ambient temperature and battery remaining SOC, and estimate limit torque for high-voltage accessories Tlim ; The accelerator pedal opening Ped and the accelerator pedal opening change rate Dped, vehicle speed ν As input, after fuzzy processing, the compensation torque is determined according to the established control rules. Tini ; Take the limiting torque Tlim , Compensation torque Tini and motor torque limit Tmotmax The minimum value is the required torque. Tqdem .

[0015] The expected torque output of the driver's intention is calibrated according to the current motor speed and the accelerator pedal opening Ped in different modes, and the driver's expected torque demand in the D gear is calculated by looking up the table; The vehicle mode recognition is to meet the driving conditions, specifically, the vehicle is driven, the gear drive mode is in progress and there is no brake pedal intervention; When the driving conditions are met, the initial torque is calculated Tq : Tq = Accped × Tmax ; in Accped is the accelerator pedal opening value in D gear driving mode, Tmax It is the maximum driving torque corresponding to the current speed of the motor.

[0016] Limiting torque Tlim for: ; ; Among them, the battery overcurrent coefficient is ß , n is the motor speed, Tmot is the real-time torque fed back by the motor, and the maximum allowable discharge power of the battery is Pbmax , the actual discharge power of the battery is Pbart , the actual battery voltage is Ubart, the maximum allowable pulse discharge current of the battery is Ibmax, and the real-time discharge current of the battery is Ibart, Pbmax - Pbart Battery overcurrent limit power, including power consumption of high-voltage accessories Paux , the power consumption of the vehicle high-voltage wiring harness Plin; High-voltage accessories include DCDC converters, AC air conditioning compressors, and PCT heaters; The torque limit imposed by the external ambient temperature and the battery SOC is realized by the maximum allowable pulse discharge current Ibmax of the battery. The torque is adjusted according to the difference between the real-time discharge current Ibart and the current maximum allowable pulse discharge current Ibmax of the battery, that is, according to the actual ambient temperature and the remaining SOC of the battery, the internal consumption of the battery, and the power consumption of the high-voltage accessories. Paux , the vehicle high voltage harness power consumption Plin, the limiting torque Tlim Make an estimate.

[0017] The maximum allowable pulse discharge current Ibmax of the battery will change in real time with the ambient temperature and SOC of the battery. In particular, low temperature environments and low SOC (below 15%) of the battery will greatly limit the maximum allowable pulse discharge current Ibmax of the battery, and may even cause overcurrent failure of the power battery.

[0018] Due to the characteristics of lithium iron phosphate batteries, the effects of low temperature are as follows: at 0℃ to -10℃, the maximum allowable pulse discharge current Ibmax of the battery will decay by about 50%, at -10℃ to -25℃, the maximum allowable pulse discharge current Ibmax of the battery will also decay by about half, and at an ambient temperature of -35℃, the battery almost loses its discharge ability.

[0019] The effects of battery SOC attenuation are as follows: a 30% to 20% SOC change will cause the battery's maximum allowable pulse discharge current Ibmax to attenuate by about 50%, and a 20% to 10% SOC change will also cause the battery's maximum allowable pulse discharge current Ibmax to attenuate by about half; but a 30%-100% battery SOC change and a 0℃-50℃ temperature change will not have a significant effect on the battery's maximum allowable pulse discharge current Ibmax.

[0020] According to the actual vehicle speed, the initial torque Tq Based on the partial compensation torque Tcomp, used to increase power output to achieve the driver's driving intention under rapid acceleration and compensate for torque Tini for: Tini = Tq + Tcomp .

[0021] Due to the excessive partial compensation torque Tcomp It will cause the vehicle to have impact and vibration. In order to ensure the comfort of the whole vehicle, it is necessary to adjust the impact intensity according to the K Partial compensation torque Tcomp Limit the impact K The formula is: ; in, a is the acceleration, ν is vehicle speed, impact K Expressed as the rate of change of acceleration, da / dt , impact K If the vehicle speed is expressed as d 2 ν / dt 2 .

[0022] Compensation torque Tini Using fuzzy control algorithm, the accelerator pedal opening Ped, vehicle speed ν and the accelerator pedal opening rate Dped as input to compensate the torque Tini As output, a torque compensation fuzzy rule table is established; the accelerator pedal opening change rate Dped contains five fuzzy subsets: VS1, S1, M1, B1, VB1, and the domain is 0-100%; vehicle speed ν The variables include three fuzzy subsets: S2, M2, B2, and the domain is 0-120km / h; the accelerator pedal opening Ped includes three fuzzy subsets: S3, M3, B3, and the domain is 0-100%; the compensation torque Tini It includes seven fuzzy subsets: ES, VS2, S4, M4, B4, VB2, EB, and the domain is 0-30Nm; Among them, ES is extremely small, VS1 and VS2 are relatively small, S1, S2, S3, and S4 are small, M1, M2, M3, and M4 are medium, B1, B2, B3, and B4 are large, VB1 and VB2 are relatively large, and EB is extremely large.

[0023] When the vehicle is starting or climbing a slope, the speed is in the smaller VS1 speed range. At this time, in order to obtain more power, it is necessary to increase the torque change under the same accelerator pedal opening Ped. In this way, a larger VB2 or a maximum EB compensation torque is given. TiniTo meet the acceleration needs, to meet the acceleration needs, and fully guarantee the vehicle's power output.

[0024] When the vehicle is traveling in the suburbs or on national highways, the vehicle speed is in the medium M1 speed range, the vehicle acceleration demand is mostly overtaking acceleration conditions, and the torque change of the accelerator pedal opening Ped is moderate, then the compensation torque of S4, M4 or B4 is increased. Tini ; When the vehicle is running at high speed, in order to maintain a large VB1 speed and keep it in a constant power range, the accelerator pedal opening change rate Dped and the torque change of the accelerator pedal opening Ped are small. At this time, the compensation torque of the small VS2 or the extremely small ES is used. Tini .

[0025] Torque compensation fuzzy rule table: ; The magnitude of the compensation torque is positively correlated with the accelerator pedal opening rate Dped, and the accelerator pedal opening Ped, the accelerator pedal opening rate Dped, and the vehicle speed ν As the fuzzy control input, the compensation torque Tini is used as the fuzzy control output, with a total of 45 fuzzy rules.

[0026] Required torque Tqdem for: Tqdem = MIN ( Tlim , Tini, Tmotmax ); in, Tmotmax is the motor torque limit, which is the peak torque of the reference motor external characteristics; the required torque Tqdem After the output, when it is detected that the motor torque fluctuation exceeds the threshold, PID active damping control is performed to smooth the expected output torque of the drive motor to prevent shaking and improve the driving stability of the vehicle. Among them, the drive motor torque fluctuation is detected by the motor controller MCU, and the torque fluctuation threshold needs to be calibrated according to the motor performance, which is a calibration value.

Claims

1. A method for estimating required torque based on power consumption and torque compensation, characterized in that: include: When the vehicle is driven, the sensors of each component monitor the vehicle's accelerator pedal opening Ped and vehicle speed in real time. ν The accelerator pedal opening rate Dped parameter is used to filter the accelerator pedal opening Ped. The expected torque output of the driver's intention and the vehicle driving mode are identified according to the current motor speed, the accelerator pedal opening rate Dped parameter and the filtered accelerator pedal opening Ped. The initial torque is calculated Tq ; Calculate battery consumption and battery overcurrent power following limit based on actual ambient temperature and battery remaining SOC, and estimate limit torque for high-voltage accessories Tlim ; The accelerator pedal opening Ped and the accelerator pedal opening change rate Dped, vehicle speed ν As input, after fuzzy processing, the compensation torque is determined according to the established control rules. Tini ; Take the limiting torque Tlim , Compensation torque Tini and motor torque limit Tmotmax The minimum value is taken as the required torque Tq .

2. The method for estimating required torque based on power consumption and torque compensation according to claim 1, characterized in that: The desired torque output intended by the driver is calibrated according to the current motor speed and the accelerator pedal opening Ped in different modes, and the driver's desired torque demand in the D gear is calculated by looking up a table; The vehicle mode recognition is to meet the driving conditions, specifically, the vehicle is driven in gear drive mode without brake pedal intervention; When the driving conditions are met, the initial torque is calculated Tq : Tq = Accped × Tmax ； in Accped is the accelerator pedal opening value in D gear driving mode, Tmax It is the maximum driving torque corresponding to the current speed of the motor.

3. The method for estimating required torque based on power consumption and torque compensation according to claim 2, characterized in that: The limiting torque Tlim for: ； ； Among them, the battery overcurrent coefficient is ß , n is the motor speed, Tmot is the real-time torque fed back by the motor, and the maximum allowable discharge power of the battery is Pbmax , the actual discharge power of the battery is Pbart , the actual battery voltage is Ubart, the maximum allowable pulse discharge current of the battery is Ibmax, and the real-time discharge current of the battery is Ibart, Pbmax-Pbart Battery overcurrent limit power, including power consumption of high-voltage accessories Paux , the power consumption of the vehicle high-voltage wiring harness Plin; The high-voltage accessories include a DCDC converter, an AC air-conditioning compressor, and a PCT heater; The torque limit imposed by the external ambient temperature and the battery SOC is realized by the maximum allowable pulse discharge current Ibmax of the battery. The torque is adjusted according to the difference between the real-time discharge current Ibart and the current maximum allowable pulse discharge current Ibmax of the battery, that is, according to the actual ambient temperature and the remaining SOC of the battery, the internal consumption of the battery, and the power consumption of the high-voltage accessories. Paux , the vehicle high voltage harness power consumption Plin, the limiting torque Tlim Make an estimate.

4. The method for estimating required torque based on power consumption and torque compensation according to claim 1, characterized in that: According to the actual vehicle speed, the initial torque Tq Based on the partial compensation torque Tcomp , used to increase power output to achieve the driver's driving intention under rapid acceleration and compensate for torque Tini for: Tini = Tq + Tcomp 。 5. The method for estimating required torque based on power consumption and torque compensation according to claim 4, characterized in that: Due to the excessive partial compensation torque Tcomp Will cause the vehicle to have impact and vibration. In order to ensure the comfort of the whole vehicle, it is necessary to Impact strength K Partial compensation torque Tcomp Limit the impact K The formula is: ； in, a is the acceleration, ν is vehicle speed, impact K Expressed as the rate of change of acceleration, da / dt , impact K If the vehicle speed is expressed as d 2 ν / dt 2 .

6. The method for estimating required torque based on power consumption and torque compensation according to claim 1, characterized in that: The compensation torque Tini Using fuzzy control algorithm, the accelerator pedal opening Ped, vehicle speed ν and the accelerator pedal opening rate Dped as input to compensate the torque Tini As output, a fuzzy rule table for torque compensation is established; The accelerator pedal opening change rate Dped contains five fuzzy subsets: VS1, S1, M1, B1, VB1, with a domain of 0-100%; vehicle speed ν The variables include three fuzzy subsets: S2, M2, B2, and the domain is 0-120km / h; the accelerator pedal opening Ped includes three fuzzy subsets: S3, M3, B3, and the domain is 0-100%; Compensation torque Tini It includes seven fuzzy subsets: ES, VS2, S4, M4, B4, VB2, EB, and the domain is 0-30Nm; Among them, ES is extremely small, VS1 and VS2 are relatively small, S1, S2, S3, and S4 are small, M1, M2, M3, and M4 are medium, B1, B2, B3, and B4 are large, VB1 and VB2 are relatively large, and EB is extremely large.

7. The method for estimating required torque based on power consumption and torque compensation according to claim 6, characterized in that: When the vehicle is starting or climbing a slope, the speed is in the smaller VS speed range. At this time, in order to obtain more power, it is necessary to increase the torque change under the same accelerator pedal opening Ped. In this way, a larger VB or a maximum EB compensation torque is given. Tini To meet the acceleration needs; When the vehicle is traveling in the suburbs or on national highways, the vehicle speed is in the medium M speed range, the vehicle acceleration demand is mostly for overtaking acceleration, and the torque change of the accelerator pedal opening Ped is moderate, then the compensation torque of S, M or B is increased. Tini ; When the vehicle is running at high speed, in order to maintain a large VB speed and keep it in the constant power range, the accelerator pedal opening change rate Dped and the torque change of the accelerator pedal opening Ped are small. At this time, the compensation torque of the small VS or extremely small ES is used to compensate. Tini .

8. The method for estimating required torque based on power consumption and torque compensation according to claim 1, characterized in that: The required torque Tq for: Tqdem=MIN ( Tlim ， Tini, Tmotmax )； in, Tmotmax is the motor torque limit, which is the peak torque of the reference motor external characteristics; the required torque Tq After the output, when it is detected that the motor torque fluctuation exceeds the threshold, PID active damping control is performed to prevent shaking, and the expected output torque of the drive motor is processed to smoothen the vehicle's driving stability by preventing shaking.

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