Energy feedback control method for electric vehicle controller
By adopting the dual closed-loop control of bus current and voltage in the electric vehicle controller and the energy feedback curve selection, the shortcomings of traditional electric vehicle controllers in the range and torque control are solved, and longer range and better Cycling experience.
Patent Information
- Application Number
- CN202310116434.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-02-15
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2043-02-15
AI Technical Summary
Traditional electric vehicle controllers lack effective energy feedback strategies, resulting in limited range in uphill and downhill areas and poor torque control effect, affecting the user's riding experience.
Using double closed-loop control based on bus current and voltage, the first and second torque current components are generated, and the corresponding energy feedback curve is selected according to the vehicle speed, and the torque current reference value is obtained in a closed-loop control to ensure that the motor is in energy. The feedback state is formed and a smooth energy feedback curve is constructed during the sliding stage.
It realizes effective limits on the return charge current and return charge voltage, increases the range, and improves the user's riding experience, ensuring a smooth transition of the energy feedback process.
Smart Images
Figure CN115871469B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of electric vehicle control, and in particular to an energy feedback control method for an electric vehicle controller. Background Art
[0002] For electric vehicles, cruising range is a very critical performance indicator. From the perspective of the controller, developing an energy feedback strategy can increase the cruising range to a certain extent, especially in places with many ups and downs. Energy feedback has a greater impact on cruising range. Traditional electric vehicle controllers generally do not have energy feedback strategies. A small number of them have energy feedback strategies, but the torque control effect is poor and torque mutations are prone to occur, affecting the user's riding experience. Summary of the invention
[0003] In view of the above problems and technical requirements, the inventors have proposed an energy feedback control method for an electric vehicle controller. The technical solution of the present invention is as follows:
[0004] An electric vehicle controller energy feedback control method, characterized in that the method comprises:
[0005] Generate a first torque current component and a second torque current component respectively based on the sampled actual value of the bus current and the actual value of the bus voltage;
[0006] When the electric vehicle is in the gliding stage, a corresponding energy feedback curve is selected based on the instantaneous vehicle speed when the handlebar is released, and a third torque current component is generated based on the energy feedback curve; wherein the energy feedback curve is a smooth curve in which the feedback torque changes with the vehicle speed;
[0007] The first, second and third torque current components are combined to obtain a torque current given value, and the torque current given value is used as an input of a torque current closed-loop control, thereby controlling the motor to be in an energy feedback state.
[0008] A further technical solution is that a method for respectively generating a first torque current component and a second torque current component based on the sampled actual value of the bus current and the actual value of the bus voltage comprises:
[0009] The bus current given value and the sampled bus current actual value are used to generate a corresponding first torque current component through a PI regulator;
[0010] The bus voltage given value and the sampled bus voltage actual value are used to generate a corresponding second torque current component through a PI regulator.
[0011] A further technical solution is that the method for selecting a corresponding energy feedback curve based on the instantaneous vehicle speed when the handlebar is released includes:
[0012] Define N0, N1, N2, and N3 as the speed parameters of the electric vehicle, where N0 > N1 and N2 > N3; among them, N0 is the instantaneous vehicle speed when the throttle is released, and N3 is used as the threshold for determining whether to enter the free coasting stage;
[0013] Set the feedback torque to increase linearly when changing from N0 to N1, and define the line segment corresponding to the change of the feedback torque from N0 to N1 as the first change stage of the energy feedback curve; set the feedback torque to decrease linearly when changing from N2 to N3, and define the line segment corresponding to the change of the feedback torque from N2 to N3 as the second change stage of the energy feedback curve;
[0014] If N1 >= N2, the constructed energy feedback curve is: as the vehicle speed gradually decreases, the feedback torque first enters the first change stage, stabilizes at the maximum feedback torque T1 for a certain period of time and then enters the second change stage, or the feedback torque first enters the first change stage and then enters the second change stage;
[0015] If N3 < N1 < N2, define the feedback torque at the intersection of the line segments corresponding to the first change stage and the second change stage as T2, select the corresponding energy feedback curve according to the relationship between T2 and T1, or turn off the energy feedback and directly enter the free coasting stage, and the third torque current component is zero;
[0016] If N1 <= N3, or N0 <= N3, turn off the energy feedback and directly enter the free coasting stage, and the third torque current component is zero.
[0017] Its further technical solution is that the method of selecting the corresponding energy feedback curve according to the relationship between T2 and T1, or turning off the energy feedback and directly entering the free coasting stage includes:
[0018] When T2 > 0.5T1, intercept the line segment corresponding to the feedback torque from N1 to N3 when T2 = 0.5T1 from the line segment corresponding to the second change stage and define it as the third change stage of the energy feedback curve. Then the constructed energy feedback curve is: as the vehicle speed gradually decreases, the feedback torque first enters the first change stage and then enters the third change stage;
[0019] When T2 <= 0.5T1, turn off the energy feedback and directly enter the free coasting stage.
[0020] Its further technical solution is that the method also includes:
[0021] Determine the working stage of the electric vehicle. When the electric vehicle is in the braking stage, the third torque current component can also be generated;
[0022] Integrate the first, second, and third torque current components to obtain the torque current given value, and use the torque current given value as the input of the torque current closed-loop control to control the motor to be in the energy feedback state.
[0023] A further technical solution is that the method for determining the working stage of the electric vehicle includes:
[0024] When the brake signal is at an invalid level, the electric vehicle is in the coasting stage; when the brake signal is at a valid level, the electric vehicle is in the braking stage.
[0025] A further technical solution is that when the electric vehicle is in the braking stage, an upper limit and a lower limit of the feedback torque need to be set so that the braking speed can quickly reach the target value.
[0026] A further technical solution is that the upper limit of the bus current given value is the maximum recharge current allowed by the battery, and the upper limit of the bus voltage given value is the maximum recharge voltage allowed by the battery.
[0027] Its further technical solution is that the method further comprises:
[0028] When the electric vehicle is in the coasting stage, the feedback torque strength corresponding to the energy feedback curve can be adjusted.
[0029] A further technical solution is that the method for adjusting the feedback torque strength corresponding to the energy feedback curve includes:
[0030] The value of the maximum feedback torque T1 corresponding to the energy feedback curve is changed by combining the throttle and P gear, so as to realize multi-gear adjustment from no energy feedback to maximum energy feedback.
[0031] The beneficial technical effects of the present invention are:
[0032] This method uses dual closed-loop control of bus voltage and bus current to limit the recharge current and recharge voltage, and generates the first and second torque current components. The stage of motor energy feedback is determined according to the braking state. When in the coasting stage, the corresponding energy feedback curve is adaptively selected in combination with different instantaneous vehicle speeds when the handlebar is released to generate a third torque current component. Alternatively, when in the braking stage, the third torque current component can also be generated. Finally, the three torque current components are combined to obtain a torque current given value, which acts on the torque current closed-loop control to form a whole control closed loop to achieve energy recovery. In the coasting stage, the feedback torque corresponding to the energy feedback curve constructed based on the speed is smoothly transitioned, which improves the user's riding experience while ensuring an increase in cruising range. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 It is a working schematic diagram of the energy feedback control method of the electric vehicle controller provided in this application.
[0034] Figure 2 This is the first energy feedback curve diagram provided by this application.
[0035] Figure 3 This is the second energy feedback curve diagram provided by this application.
[0036] Figure 4 This is the third energy feedback curve diagram provided by this application.
[0037] Figure 5 It is a logic diagram for selecting an energy feedback curve provided in this application. DETAILED DESCRIPTION
[0038] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.
[0039] like Figure 1 As shown, this embodiment provides an electric vehicle controller energy feedback control method, comprising the following steps:
[0040] Step 1: Based on the actual value of the bus current obtained by sampling I and the actual value of bus voltage V Generating a first torque current component and a second torque current component respectively includes:
[0041] Set the bus current to a given value I ref And the actual value of the bus current sampled I The corresponding first torque current component is generated by the PI regulator. V ref And the actual value of the bus voltage sampled V The corresponding second torque current component is generated by a PI regulator.
[0042] Optionally, you also need to set the bus current setpoint in this step I ref and bus voltage setpoint V ref The upper limit of bus current is: I ref The upper limit is the maximum recharge current allowed by the battery, and the bus voltage is set to V ref The upper limit is the maximum recharge voltage allowed by the battery. When the actual value exceeds the set upper limit, the first and second torque current components are outputted to zero. By setting the corresponding upper limit, the motor controller is prevented from being damaged when the recharge voltage is too high, and the battery is prevented from being damaged when the recharge current is too large.
[0043] Step 2: Determine the working stage of the electric vehicle.
[0044] When the brake signal is at an invalid level, the electric vehicle is in the coasting stage; when the brake signal is at a valid level, the electric vehicle is in the braking stage. Optionally, in this embodiment, the valid level is set to a high level, and the brake signal is used as the switch for switching the working stage.
[0045] Step 3: When the electric vehicle is in the coasting stage, select a corresponding energy recovery curve based on the instantaneous vehicle speed when the throttle is released, and generate a third torque current component based on the energy recovery curve.
[0046] Among them, the implementation method of selecting a corresponding energy recovery curve based on the instantaneous vehicle speed when the throttle is released includes:
[0047] The energy recovery curve is a smooth curve of the feedback torque varying with the vehicle speed. The vertical axis of the curve is the feedback torque T, and the horizontal axis of the curve is the electric vehicle speed N. Take N0, N1, N2, N3 among them, and assume N0 > N1, N2 > N3. Among them, N0 is the instantaneous vehicle speed when the throttle is released, and N3 is used as the threshold for judging whether to enter the free coasting stage, generally about 15 yards. It is set that the feedback torque increases linearly when changing from N0 to N1, and the line segment corresponding to the change of the feedback torque from N0 to N1 is defined as the first change stage of the energy recovery curve; it is set that the feedback torque decreases linearly when changing from N2 to N3, and the line segment corresponding to the change of the feedback torque from N2 to N3 is defined as the second change stage of the energy recovery curve. Considering that the user may cut into the coasting stage at any speed, different N0 correspond to different energy recovery curves. The following is analyzed in three cases:
[0048] <1> If N1 >= N2 (i.e., N3 < N2 <= N1 < N0), the constructed energy recovery curve is: as the vehicle speed gradually decreases, the feedback torque first enters the first change stage, stabilizes at the maximum feedback torque T1 for a certain period of time, and then enters the second change stage, as Figure 2 shown. In the figure, the difference in speed change corresponding to the feedback torque current from 0 to the maximum from N0 to N1, the speed change range corresponding to the maximum torque current from N1 to N2, and the speed change from the maximum torque current to 0 from N2 to N3. Among them, the feedback torque current and the feedback torque generally exist in proportion. The feedback torque corresponding to the energy recovery curve shown in the figure increases linearly from zero to the maximum as the speed decreases from N0 to N1, the feedback torque stabilizes at the maximum during the period when the speed decreases from N2 to N3, and finally decreases linearly from the maximum to zero as the speed decreases from N2 to N3. The reason for designing it as a trapezoidal curve is that if the feedback torque changes suddenly at the moment of releasing the throttle, it will affect the user's riding experience. Therefore, when the speed slowly decreases to zero, the torque also slowly decreases to 0, avoiding the sudden change of torque from affecting the user.
[0049] Alternatively, the constructed energy feedback curve is as follows: as the vehicle speed gradually decreases, the feedback torque first enters the first change stage and then enters the second change stage. Although this curve lacks the stable stage of the feedback torque, the feedback torque also slowly decreases to 0 as the speed decreases, which also belongs to a smooth transition.
[0050] <2>If N3 < N1 < N2, there are two cases at this time. One is N3 < N1 < N2 < N0, and the other is N3 < N1 < N0 < N2. The methods for constructing the curve in both cases are the same. Taking the first case as an example: Define the feedback torque at the intersection of the line segments corresponding to the first change stage and the second change stage as T2. Select the corresponding energy feedback curve according to the relationship between T2 and T1, or turn off the energy feedback and directly enter the free coasting stage. For the convenience of implementing the algorithm, when (N2 - N1) = (N1 - N3), the corresponding torque T2 = 0.5T1. Then the specific implementation methods include:
[0051] ① When T2 > 0.5T1, that is, (N2 - N1) < (N1 - N3), to facilitate curve construction without affecting the driving / riding experience, intercept the line segment corresponding to the feedback torque changing from N1 to N3 when T2 = 0.5T1 from the line segment corresponding to the second change stage and define it as the third change stage of the energy feedback curve. Then the constructed energy feedback curve is: as the vehicle speed gradually decreases, the feedback torque first enters the first change stage and then enters the third change stage. This curve also realizes a smooth transition, as Figure 3 shown in the shadow.
[0052] ② When T2 <= 0.5T1, that is, (N2 - N1) >= (N1 - N3), at this time, both the feedback torque current and the speed are relatively low, so turn off the energy feedback and directly enter the free coasting stage, and the third torque current component is zero.
[0053] <3>If N1 <= N3, or N0 <= N3, similarly, at this time, both the feedback torque current and the speed are relatively low. The corresponding constructed curve is as Figure 4 shown. At this time, T3 is very small and the speed is also relatively low, which is no longer suitable for curve construction. So turn off the energy feedback and directly enter the free coasting stage, and the third torque current component is zero. The overall logic of the above process of constructing the energy feedback curve is as Figure 5 shown.
[0054] Step 4: Synthesize the first, second, and third torque current components to obtain the torque current given value. Take the torque current given value as the input of the torque current closed-loop control, generate the corresponding q-axis voltage through the PI regulator, and then form the entire control closed-loop through SVPWM (Space Vector Pulse Width Modulation) to control the motor to be in the energy feedback state.
[0055] Among them, for the method of integrating the three torque current components, the torque current given value can be obtained by summing them up, or the first and second torque components can be defined as coefficients, and then multiplied with the third torque current component respectively and then summed to obtain the torque current given value, or other existing methods can be used, and this application does not impose any restrictions on this.
[0056] Step 5: When the electric vehicle is in the gliding stage, the feedback torque strength corresponding to the energy feedback curve can be adjusted, including:
[0057] The value of the maximum feedback torque T1 corresponding to the energy feedback curve is changed by using the operation mode of the combination of the throttle and the P gear, so as to realize the multi-gear adjustment between no energy feedback and maximum energy feedback. Optionally, the adjustment range set in this embodiment is divided into 4 gears, and the default is no energy feedback. The change mode is: turn the throttle before releasing the P gear, and then press the P gear. The feedback strength increases with each operation. , after the fourth operation, it returns to the state of no energy feedback, completing an operation cycle, and the feedback force setting can be displayed on the instrument.
[0058] Step 6: When the electric vehicle is in the braking stage, the third torque current component can also be generated. Then the first, second and third torque current components are combined to obtain a torque current given value, which is used as the input of the torque current closed-loop control to control the motor in the energy feedback state.
[0059] Optionally, in this step, the upper and lower limits of the feedback torque need to be set so that the braking speed can quickly reach the target value. Frequent wear and heating of ordinary brake pads will reduce the braking effect. Therefore, in this embodiment, electronic brakes are used to replace ordinary brake pads, which increases the reliability of braking, ensures rapid braking, and improves driving safety. For the generation of the third torque current component in the braking stage, this embodiment adopts the existing method, and its specific implementation steps will not be repeated in detail here.
[0060] The above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.
Claims
1. An electric vehicle controller energy feedback control method, characterized in that: The method includes: generating a first torque current component and a second torque current component respectively based on the actual value of the bus current and the actual value of the bus voltage obtained by sampling; when the electric vehicle is in the coasting stage, selecting a corresponding energy feedback curve based on the instantaneous vehicle speed when the throttle is released, and generating a third torque current component based on the energy feedback curve; wherein the energy feedback curve is a smooth curve of the feedback torque varying with the vehicle speed; combining the first, second, and third torque current components to obtain a torque current set value, and using the torque current set value as the input of the torque current closed-loop control, so as to control the motor to be in the energy feedback state; wherein, the method of selecting a corresponding energy feedback curve based on the instantaneous vehicle speed when the throttle is released includes: defining N0, N1, N2, N3 as electric vehicle speed parameters, and N0 > N1, N2 > N3; where N0 is the instantaneous vehicle speed when the throttle is released, and N3 is used as the threshold for judging whether to enter the free coasting stage; setting the feedback torque to increase linearly when changing from N0 to N1, and defining the line segment corresponding to the change of the feedback torque from N0 to N1 as the first change stage of the energy feedback curve; setting the feedback torque to decrease linearly when changing from N2 to N3, and defining the line segment corresponding to the change of the feedback torque from N2 to N3 as the second change stage of the energy feedback curve; if N1 >= N2, the constructed energy feedback curve is: as the vehicle speed gradually decreases, the feedback torque first enters the first change stage, stabilizes at the maximum feedback torque T1 for a certain period of time and then enters the second change stage, or the feedback torque first enters the first change stage and then enters the second change stage; if N3 < N1 < N2, defining the feedback torque at the intersection of the line segments corresponding to the first change stage and the second change stage as T2, and selecting a corresponding energy feedback curve according to the relationship between T2 and T1, or closing the energy feedback and directly entering the free coasting stage, and the third torque current component is zero; if N1 <= N3, or N0 <= N3, closing the energy feedback and directly entering the free coasting stage, and the third torque current component is zero.
2. The electric vehicle controller energy feedback control method according to claim 1, characterized in that: The method of generating a first torque current component and a second torque current component respectively based on the actual value of the bus current and the actual value of the bus voltage obtained by sampling includes: generating a corresponding first torque current component by passing the bus current set value and the sampled actual value of the bus current through a PI regulator; generating a corresponding second torque current component by passing the bus voltage set value and the sampled actual value of the bus voltage through a PI regulator.
3. The electric vehicle controller energy feedback control method according to claim 1, characterized in that: The method of selecting a corresponding energy feedback curve according to the relationship between T2 and T1, or closing the energy feedback and directly entering the free coasting stage includes: when T2 > 0.5T1, intercepting the line segment corresponding to the feedback torque from N1 to N3 when T2 = 0.5T1 from the line segment corresponding to the second change stage and defining it as the third change stage of the energy feedback curve, then the constructed energy feedback curve is: as the vehicle speed gradually decreases, the feedback torque first enters the first change stage and then enters the third change stage; when T2 <= 0.5T1, closing the energy feedback and directly entering the free coasting stage.
4. The electric vehicle controller energy feedback control method according to claim 1, characterized in that: The method further includes: Determine the working stage of the electric vehicle. When the electric vehicle is in a braking stage, a third torque current component can also be generated; The first, second and third torque current components are combined to obtain a torque current given value, which is used as an input for torque current closed-loop control, thereby controlling the motor to be in an energy feedback state.
5. The electric vehicle controller energy feedback control method according to claim 4, characterized in that: The method for determining the working stage of the electric vehicle comprises: When the brake signal is at an invalid level, the electric vehicle is in the coasting stage; when the brake signal is at a valid level, the electric vehicle is in the braking stage.
6. The electric vehicle controller energy feedback control method according to claim 4, characterized in that: When the electric vehicle is in the braking stage, the upper and lower limits of the feedback torque need to be set so that the braking speed can quickly reach the target value.
7. The electric vehicle controller energy feedback control method according to claim 2, characterized in that: The upper limit of the bus current set value is the maximum recharge current allowed by the battery, and the upper limit of the bus voltage set value is the maximum recharge voltage allowed by the battery.
8. The electric vehicle controller energy feedback control method according to any one of claims 1 to 7, characterized in that: The method further comprises: When the electric vehicle is in the coasting stage, the feedback torque strength corresponding to the energy feedback curve can be adjusted.
9. The electric vehicle controller energy feedback control method according to claim 8, characterized in that: The method for adjusting the feedback torque strength corresponding to the energy feedback curve includes: The value of the maximum feedback torque T1 corresponding to the energy feedback curve is changed by combining the throttle and P gear, so as to realize multi-gear adjustment from no energy feedback to maximum energy feedback.