A motor torque zero-crossing response control strategy for an electric vehicle

Abstract

The application discloses a motor torque zero-crossing response control strategy for an electric vehicle, wherein a preset torque zero-crossing interval [-T max , T max ] is used to approximate a change curve of torque in the zero-crossing interval by a curve image of an exponential function y=a x , and only one parameter a needs to be adjusted to control the change of torque in the zero-crossing interval; the strategy not only reduces the torque debugging time in the zero-crossing stage, but also makes the motor torque in the zero-crossing stage in a gentle change state, can weaken the instantaneous speed fluctuation when the positive and negative torques of the motor are switched, improves the smoothness of vehicle operation, and is beneficial to reducing the wear of the motor.

Description

Technical Field

[0001] This invention relates to the field of motor control for new energy vehicles, and in particular to a motor torque zero-crossing response control strategy for electric vehicles. Background Technology

[0002] Traditional automobiles typically use internal combustion engines for power, which accelerate the consumption of limited human energy resources and cause serious environmental problems. Therefore, new energy vehicles, characterized by zero emissions, low heat radiation, low noise, and environmental optimization, have gained significant attention and popularity. However, due to the backlash in the gears and splines of electric vehicle power transmission components, a grinding or jerking phenomenon occurs when accelerating and decelerating during start-up and driving, severely reducing vehicle comfort.

[0003] Currently, the common method to avoid gear grinding is to slow down the response speed of the zero-crossing torque to reduce the impact and collision between gears, thereby reducing gear grinding. However, the commonly used method generally uses a quadratic function y = a·x to change the torque. 2 +b·x requires adjusting two parameters, a and b, and the torque slope change curve is singular, making it difficult to adapt to different vehicles. Furthermore, the large number of parameters to be adjusted during actual debugging results in a long debugging time. Therefore, there is an urgent need for a motor torque zero-crossing response control strategy for electric vehicles that avoids gear grinding and can reduce debugging time to solve the above problems. Summary of the Invention

[0004] To address the issue of gear backlash in electric vehicles caused by the inter-tooth clearance of gear transmission components, resulting in gear grinding during acceleration and deceleration, which significantly reduces vehicle comfort, this invention proposes a motor torque zero-crossing response control strategy for electric vehicles. This strategy utilizes an exponential function y = a x The curve image is used to approximate the change of torque in the zero-crossing range. Only one parameter 'a' needs to be adjusted to achieve the effect of quadratic function regulation, thereby controlling the torque change in the zero-crossing range of the motor torque.

[0005] The technical solution adopted by this application to solve its technical problem is: to provide a motor torque zero-crossing response control strategy for electric vehicles, including the following steps,

[0006] Step 1, preset the range of slowly changing required torque as [-T] max T max ], and T max >0, when the torque is within this range, the torque slope changes slowly according to the magnitude of the torque; the range of slow torque change is [-T max T max The curve fitting for y = a is given by y = a. x, where a is a variable, and a > 0 and a ≠ 1. The value of a is adjusted according to the rate of torque change. The preset delay time for slow torque change is x = t1, and t1 is set according to the torque response delay required by the actual vehicle.

[0007] Step 2: Determine whether the torque demand of the drive motor changes from zero to positive or from zero to negative; if so, and the torque demand is greater than or equal to T. max Or less than or equal to -T max When the torque is less than T, the motor controller's torque execution value is the torque requirement value; if the torque requirement is less than T, the torque is less than T. max Or greater than -T max At this time, the function y = a x If a > 1, proceed to step 4; otherwise, proceed to step 3.

[0008] Step 3: Determine whether the torque demand of the drive motor changes from positive to zero or from negative to zero; if so, and the torque demand is greater than or equal to T. max Or less than or equal to -T max When the torque is less than T, the motor controller's torque execution value is the torque requirement value; if the torque requirement is less than T, the torque is less than T. max Or greater than -T max At this time, the function y = a x If 0 < a < 1, proceed to step 4;

[0009] Step 4: Determine if the torque requirement of the drive motor is greater than zero. If so, the torque execution value of the motor controller is T. n If not, the motor controller torque execution value is -T. n Proceed to step 5;

[0010] Step 5, calculate the exponential function y = a x The slope k; when x = t1, calculate the exponential function y = a x The value y1 changes slowly;

[0011] Step 6: Calculate the actual output torque slope k1 based on y1 and k;

[0012] Step 7: Calculate the actual required output torque T based on the actual output torque slope k1. n .

[0013] Furthermore, in step 5, y = a x Fitting the function, we get y = 1 + x[(a-1) - 0.5 × (a-1)] 2 Substituting x = t1, we get y1 = 1 + t1[(a-1) - 0.5 × (a-1)] 2 ];k=y'=lna×a x , k = lna × a xBy fitting the data, we get k = [(a-1) - 0.5 × (a-1)] 2 ]+x[(a-1)-0.5×(a-1) 2 ] 2 .

[0014] Furthermore, in step 6, a slope k2 is set when the torque is 0, and this slope k2 is not 0 when the torque is 0, in order to respond to changes in torque; then the actual output torque slope k1 = T max / {1+t1[(a-1)-0.5×(a-1) 2 ]}×{[(a-1)-0.5×(a-1) 2 ]+x[(a-1)-0.5×(a-1) 2 ] 2}+k2.

[0015] Furthermore, in step 7, at a certain time t n The torque is T n =T (n-1) +k1×(t (n) -t (n-1) ).

[0016] Furthermore, T in step 1 max To calibrate the adjustable value, a preset T is used. max The value is 5% to 15% of the rated torque of the motor, and in step 1, 0ms < t1 ≤ 100ms.

[0017] Furthermore, the slope 0 < k2 ≤ 0.001.

[0018] Furthermore, the change in torque demand from zero to positive in step 2 corresponds to the process where the torque demand value changes from zero to positive after the motor controller switches from standby mode to torque mode each time the operating mode changes.

[0019] Furthermore, the torque demand value is provided by the vehicle controller to the motor controller, and the motor output torque is equal to the torque execution value of the motor controller.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] The zero-crossing response control strategy adopted in this invention only requires adjusting one parameter to control the torque change of the electric vehicle motor in the zero-crossing range, which greatly reduces the debugging time; and makes the motor torque in the zero-crossing range change slowly, which can reduce the instantaneous speed fluctuation when the motor switches between positive and negative torque, avoid gear grinding, improve the smoothness of the whole vehicle, and help reduce motor wear. Attached Figure Description

[0022] Figure 1 A graph showing the relationship between the zero-crossing range of electric vehicle motor torque and time.

[0023] Figure 2 The curve showing the change in torque of an electric vehicle motor from negative to positive within the zero-crossing range;

[0024] Figure 3 The curve showing the change in the zero-crossing range of electric vehicle motor torque from positive to negative values;

[0025] Figure 4 When a > 1, the exponential function y = a x Images;

[0026] Figure 5 When 0 < a < 1, the exponential function y = a x The image. Detailed Implementation

[0027] The electric vehicle motor torque zero-crossing control method of the present invention will be further described below with reference to specific embodiments, so as to provide a more complete and clear explanation of the technical solution of the present invention.

[0028] like Figure 1 , Figure 2 and Figure 3 The illustrated motor torque zero-crossing response control strategy for electric vehicles includes the following steps:

[0029] Step 1, preset the range of slowly changing required torque as [-T] max T max ], and T max >0, when the torque is within this range, the torque slope changes slowly according to the magnitude of the torque, T max To calibrate the adjustable value, a preset T is used. max The torque is 5% to 15% of the motor's rated torque; the torque varies slowly within the range [-T]. max T max The curve fitting for y = a is given by y = a. x , where a is a variable, and a > 0 and a ≠ 1, the magnitude of a is adjusted according to the speed of torque change; the preset delay time for slow torque change is x = t1, and in step 1 0ms < t1 ≤ 100ms, t1 is set according to the torque response delay required by the actual vehicle.

[0030] Step 2: Determine whether the torque demand of the drive motor changes from zero to positive or from zero to negative; if so, and the torque demand is greater than or equal to T. max (as shown at point A) or less than or equal to -T max (As shown at point F in the figure), the torque execution value of the motor controller is the torque demand value; if the torque demand is less than T... maxOr greater than -T max At this time, the function y = a x If a > 1, proceed to step 4; otherwise, proceed to step 3.

[0031] Step 3: Determine whether the torque demand of the drive motor changes from positive to zero or from negative to zero; if so, and the torque demand is greater than or equal to T. max (as shown at point D) or less than or equal to -T max (As shown at point C in the figure), the torque execution value of the motor controller is the torque demand value; if the torque demand is less than T... max Or greater than -T max At this time, the function y = a x If 0 < a < 1, proceed to step 4;

[0032] Step 4: Determine if the torque requirement of the drive motor is greater than zero. If so, the torque execution value of the motor controller is T. n If not, the motor controller torque execution value is -T. n Proceed to step 5;

[0033] Step 5, calculate the exponential function y = a x The slope k; when x = t1, calculate the exponential function y = a x After a slowly changing value y1; y = a x Fitting the function, we get y = 1 + x[(a-1) - 0.5 × (a-1)] 2 Substituting x = t1, we get y1 = 1 + t1[(a-1) - 0.5 × (a-1)] 2 ];k=y'=lna×a x , k = lna × a x By fitting the data, we get k = [(a-1) - 0.5 × (a-1)] 2 ]+x[(a-1)-0.5×(a-1) 2 ] 2 .

[0034] Step 6: Calculate the actual output torque slope k1 based on y1 and k; set the slope k2 when the torque is 0, ensuring that the slope k2 is not 0 when the torque is 0, to respond to torque changes, 0 < k2 ≤ 0.001; then the actual output torque slope k1 = T max / {1+t1[(a-1)-0.5×(a-1) 2 ]}×{[(a-1)-0.5×(a-1) 2 ]+x[(a-1)-0.5×(a-1) 2 ] 2}+k2.

[0035] Step 7: Calculate the actual required output torque T based on the actual output torque slope k1. n At a certain moment t n The torque is T n =T (n-1) +k1×(t (n) -t (n-1) ).

[0036] By implementing this motor torque zero-crossing response control strategy for electric vehicles, tooth knocking caused by backlash in components such as gears and splines in the electric vehicle's power transmission is avoided, thus improving the smoothness and comfort of the vehicle's ride.

[0037] For those skilled in the art, the specific embodiments are merely illustrative descriptions of the present invention. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A motor torque zero-crossing response control strategy for electric vehicles, characterized in that: Includes the following steps, Step 1, preset the range of slowly changing required torque as [-T] max T max ], and T max >0, when the torque is within this range, the torque slope changes slowly according to the magnitude of the torque; the range of slow torque change is [-T max T max The curve fitting for y=a is... x , where a is a variable, and a>0 and a≠1; the preset delay time for slow torque change is x=t1, and t1 is set according to the torque response delay required by the actual vehicle. Step 2: Determine whether the torque demand of the drive motor changes from zero to positive or from zero to negative; if so, and the torque demand is greater than or equal to T. max Or less than or equal to -T max When the torque is less than T, the motor controller's torque execution value is the torque requirement value; if the torque requirement is less than T, the torque is less than T. max Or greater than -T max At this time, the function y=a x If a > 1, proceed to step 4; If not, proceed to step 3; Step 3: Determine whether the torque demand of the drive motor changes from positive to zero or from negative to zero; if so, and the torque demand is greater than or equal to T. max Or less than or equal to -T max When the torque is less than T, the motor controller's torque execution value is the torque requirement value; if the torque requirement is less than T, the torque is less than T. max Or greater than -T max At this time, the function y=a x If 0 < a < 1, proceed to step 4; Step 4: Determine if the torque requirement of the drive motor is greater than zero. If so, the torque execution value of the motor controller is T. n If not, the motor controller torque execution value is -T. n Proceed to step 5; Step 5, calculate the exponential function y=a x The slope k; when x=t1, calculate the exponential function y=a x The value y1 changes slowly; Step 6: Calculate the actual output torque slope k1 based on y1 and k; Step 7: Calculate the actual required output torque T based on the actual output torque slope k1. n .

2. The motor torque zero-crossing response control strategy for electric vehicles according to claim 1, characterized in that: In step 5, y=a x Fitting the function, we get y = 1 + x[(a-1) - 0.5 × (a-1)] 2 When x = t1, y1 = 1 + t1[(a-1) - 0.5 × (a-1)] 2 ];k=y'=lna×a x , k = lna × a x By fitting the data, we get k = [(a-1) - 0.5 × (a-1)]. 2 ]+x[(a-1)-0.5×(a-1) 2 ] 2 .

3. The motor torque zero-crossing response control strategy for electric vehicles according to claim 1, characterized in that: In step 6, the slope k2 is set when the torque is 0, and the slope k2 is not 0 when the torque is 0, in order to respond to changes in torque; then the actual output torque slope k1 = T max / {1+t1[(a-1)-0.5×(a-1) 2 ]}×{[(a-1)-0.5×(a-1) 2 ]+x[(a-1)-0.5×(a-1) 2 ] 2 }+k2.

4. The motor torque zero-crossing response control strategy for electric vehicles according to claim 1, characterized in that: In step 7, at a certain time t n The torque is T n =T (n-1) +k1×(t (n) -t (n-1) ).

5. The motor torque zero-crossing response control strategy for electric vehicles according to claim 1, characterized in that: T in step 1 max To calibrate the adjustable value, a preset T is used. max The value is 5% to 15% of the rated torque of the motor, and in step 1, 0ms < t1 ≤ 100ms.

6. The motor torque zero-crossing response control strategy for electric vehicles according to claim 3, characterized in that: The slope when the torque is 0 is 0 < k2 ≤ 0.

001.

7. The motor torque zero-crossing response control strategy for electric vehicles according to claim 1, characterized in that: In step 2, the required torque changes from zero to positive. This corresponds to the process where the torque demand value changes from zero to positive after the motor controller switches from standby mode to torque mode each time the working mode changes.

8. The motor torque zero-crossing response control strategy for electric vehicles according to any one of claims 1 to 7, characterized in that, The torque requirement value is given by the vehicle controller to the motor controller, and the motor output torque is equal to the torque execution value of the motor controller.

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