Rotor position accurate servo control method for alternating current isolation charging in electric drive system

Abstract

The invention discloses a rotor position accurate servo control method for alternating current isolation charging in an electric drive system. The method comprises the following steps of: 1, accurately sampling a direct current component in alternating current in real time; 2, designing a position proportion P controller according to the difference value between the actual position and the target position of the rotor to obtain a target value of the rotating speed of the rotor; 3, according to the difference value between the actual value and the target value of the rotor rotating speed, designing a rotating speed proportional integral (PI) controller, and obtaining a reference electromagnetic torque required by the system for realizing servo control; 4, a reference direct current component in servo control is positioned according to the real-time electrical angle of the motor and the current distribution condition under DAB working; 5, designing a proportional-integral feedback controller by taking a current direct current quantity sampling real-time value as a feedback quantity and a reference direct current component as a target value, and calculating a duty ratio offset control quantity; and 6, compensating the duty ratio offset control quantity to the corresponding bridge arm so as to realize rotor position servo control.

Description

Technical Field

[0001] This invention belongs to the field of motor servo control, specifically a method for achieving precise servo control of rotor position during AC isolated charging by reusing an electric drive system. Background Technology

[0002] AC charging and discharging is a crucial function of electric vehicles. Compared to DC charging, AC charging eliminates the need for power electronic exchange equipment in charging station construction, resulting in lower costs for both the stations and users. However, current AC charging power is lower than DC charging and charging times are longer. These drawbacks directly impact the user experience. Furthermore, AC charging requires a high-power onboard charger (OBC), which significantly increases vehicle space and weight, and substantially raises vehicle costs.

[0003] To overcome these problems, our team proposed an AC charging and discharging system and control method for vehicles (CN119261598A). This system achieves AC charging and discharging by reusing the inverter and windings of the vehicle's electric drive system, solving problems such as increased cost, increased vehicle weight, and space occupation caused by configuring an on-board computer (OBC). However, this system requires high precision in rotor position; otherwise, significant iron losses, magnet losses, and copper losses will occur, reducing charging efficiency. This invention, based on the previous patent, improves upon its shortcomings by adding precise servo control of the rotor position, achieving precise control of the rotor position during charging and improving charging efficiency. The topology of this invention is as follows: Figure 1 As shown. Summary of the Invention

[0004] The present invention addresses the shortcomings of the prior art by proposing a precise servo control method for rotor position in an AC isolated charging system for an electric drive system. This method aims to achieve precise control of the rotor position during the charging process, thereby effectively ensuring charging efficiency.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: The present invention provides a method for precise servo control of rotor position in an AC isolated charging electric drive system. The method is characterized by actively adjusting the reference duty cycle offset of the bridge arm during the dual active bridge DAB control process, thereby generating a DC component in the AC current of the primary and secondary sides, and using the electromagnetic torque generated in the motor by the DC component to achieve precise control of the rotor position.

[0006] The method for precise servo control of rotor position in an AC isolated charging electric drive system described in this invention is characterized by including the following steps: S1. Based on the switching time of the primary or secondary bridge arm of the dual active bridge DAB in the electric drive system within one cycle, the minimum value of the primary or secondary AC current is collected in real time. With the maximum value This allows for the calculation of the DC component in the alternating current. ; S2. Obtain the actual position of the rotor in the electric drive system, and design a position proportional P controller based on the set target position of the rotor to control the difference in rotor position, thereby obtaining the target speed required for the rotor to move from the actual position to the target position. S3. Obtain the actual rotor speed and, based on the target rotor speed, design a proportional-integral (PI) controller to control the difference in rotor speed, thereby obtaining the reference electromagnetic torque required for the rotor to move from the actual speed to the target speed. ; S4. Based on the real-time electrical angle of the motor in the electric drive system, the current distribution under DAB operation, and the electromagnetic torque equation, obtain the reference electromagnetic torque. With the set reference DC current The relationship is used to calculate the reference DC current. ; S5. Design a feedback proportional controller P, and use... and The difference is the input to the feedback proportional P controller, which is used to calculate the duty cycle offset control quantity. This is used to compensate the original side bridge arm for servo control of the rotor position.

[0007] Furthermore, the DC component in S1 It is calculated using equation (1): (1).

[0008] Furthermore, the reference electromagnetic torque in S4 With reference DC current The relationship is shown in equation (2): (2) In equation (2), This represents the number of pole pairs of the motor. The permanent magnet flux linkage is θ, and the rotor electrical angle is θ. For d-axis inductance, It is the q-axis inductance.

[0009] Furthermore, the method for acquiring the primary or secondary AC current in S1 is as follows: When the dual active bridge (DAB) is controlled by a single phase shift, the current value of the primary side upper arm at the turn-off moment is collected and used as the minimum value. The current value of the bridge arm on the original side at the moment of opening is collected and used as the maximum value. ; When the dual active bridge (DAB) is under dual phase-shift control or extended phase-shift control, the current value of the upper bridge arm on the primary side that has not undergone internal phase shifting at the turn-off time is collected and used as the minimum value. The current value of the lower bridge arm after internal and external phase shifts on the secondary side at the turn-off moment is collected and used as the maximum value. ; When the dual active bridge (DAB) is under triple phase-shift control, the current value of the upper bridge arm on the primary side that has not undergone the inner phase shift at the turn-off moment is collected and used as the minimum value. The current value of the upper bridge arm that has not undergone internal phase shifting at the moment of opening is collected and used as the maximum value. .

[0010] Furthermore, in S4 The current square term in equation (2) is ignored. The reference electromagnetic torque is obtained. With reference DC component The linear relationship is obtained through linear solution. Or through external offline calculation and After establishing the mapping relationship between them, the result is obtained by looking up the table. .

[0011] Furthermore, the position proportional controller P adjusts the proportional coefficient. Make near This outputs the duty cycle offset control value. .

[0012] Furthermore, the AC isolated charging method based on DAB control will be replaced with an uncontrolled rectification method based on diodes, or a synchronous rectification method based on MOSFETs.

[0013] The present invention provides an electronic device, including a memory and a processor, wherein the memory is used to store a program that supports the processor in executing the rotor position precision servo control method, and the processor is configured to execute the program stored in the memory.

[0014] The present invention discloses a computer-readable storage medium on which a computer program is stored, wherein the computer program, when executed by a processor, performs the steps of the rotor position precise servo control method.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses the average of the maximum and minimum values ​​of the AC current within one cycle as the DC component, solving the problem that the DC component of the AC current cannot be directly sampled; and proposes different sampling points for the maximum and minimum values ​​of the AC current for different phase-shift control methods, ensuring that the most accurate DC component can be obtained under each phase-shift control method, thus realizing precise servo control of the rotor position.

[0016] 2. In calculating the mapping relationship between electromagnetic torque and reference DC current, this invention greatly reduces the operational difficulty by ignoring the square term. At the same time, since the weight of the square term is very small, it will not affect the control effect. By obtaining the reference current from the electromagnetic torque table after external calculation, the problem of the nonlinearity between electromagnetic torque and reference DC current is solved.

[0017] 3. The rotor position precision servo control method proposed in this invention keeps the rotor at the position with the highest charging efficiency at all times. By adjusting in real time, it overcomes the rotor offset problem caused by internal and external influences, thereby greatly reducing the loss during charging and improving the charging efficiency of electric vehicles. Attached Figure Description

[0018] Figure 1 This is a topological diagram of the present invention; Figure 2 This is a flowchart of the method of the present invention; Figure 3 This is a DC current sampling diagram of the present invention; Figure 4 This is a speed tracking diagram for the present invention; Figure 5 This is a diagram illustrating the DC current tracking effect of the present invention. Figure 6 This is a duty cycle offset diagram for the present invention; Figure 7 This is a rotor position diagram of the present invention. Detailed Implementation

[0019] In this embodiment, a precise servo control method for rotor position in AC isolated charging of an electric drive system is applied to the precise control of rotor position during the charging process of an electric vehicle. During dual active bridge (DAB) control, the reference duty cycle offset of the bridge arm is actively adjusted to generate a DC component in the primary and secondary AC currents. The electromagnetic torque generated in the motor by this DC component is then used to achieve precise rotor position control, thereby realizing high-efficiency charging. Specifically, as... Figure 2 As shown, the servo control method is performed according to the following steps: S1. Based on the switching time of the primary or secondary bridge arm of the dual active bridge DAB in the electric drive system within one cycle, the minimum value of the primary or secondary AC current is collected in real time. With the maximum value Therefore, the DC component in the alternating current can be calculated using equation (1). ; (1) .

[0020] In this embodiment, the method for acquiring the primary or secondary AC current is as follows: (1) When the dual active bridge DAB is controlled by a single phase shift, the current value of the primary side upper bridge arm at the turn-off moment is collected and used as the minimum value. The current value of the bridge arm on the original side at the moment of opening is collected and used as the maximum value. ; (2) When the dual active bridge DAB is controlled by dual phase shift or extended phase shift, the current value of the upper bridge arm that has not undergone internal phase shift at the turn-off time is collected and used as the minimum value. The current value of the lower bridge arm after internal and external phase shifts on the secondary side at the turn-off moment is collected and used as the maximum value. ; (3) When the dual active bridge DAB is under triple phase-shift control, the current value of the upper bridge arm that has not undergone the inner phase shift at the turn-off time is collected and used as the minimum value. The current value of the upper bridge arm that has not undergone internal phase shifting at the moment of opening is collected and used as the maximum value. .

[0021] Specific data collection methods are as follows Figure 3 As shown in the figure, point A is the sampling point for the minimum value of the primary side AC current, and point B is the sampling point for the maximum value of the primary side AC current. and These represent the minimum and maximum values ​​of the primary side alternating current, respectively. The average of these two values ​​is the DC component of the current over one cycle. .

[0022] S2. Obtain the actual position of the rotor in the electric drive system, and design a position proportional P controller based on the set target position of the rotor to control the difference in rotor position, thereby obtaining the target speed required for the rotor to move from the actual position to the target position. The target position of the rotor is determined by the highest charging efficiency: (1) If two phases of the three-phase bridge arm are working, when the motor electrical angle is 330-360, 0-30, or 150-210, the BC bridge arm is working, and the target angle is 0 or 180; when the motor electrical angle is 30-90 or 210-270, the AB bridge arm is working, and the target angle is 60 or 240; when the motor electrical angle is 90-150 or 270-330, the AC bridge arm is working, and the target angle is 120 or 300.

[0023] (2) If all three phase bridge arms are working, when the motor electrical angle is 0-60 or 180-240, the AC bridge arm is connected in series and then connected in parallel with the B bridge arm to work. At this time, the target angle is 30 or 210. When the motor electrical angle is 60-120 or 240-300, the BC bridge arm is connected in series and then connected in parallel with the A bridge arm to work. At this time, the target angle is 90 or 270. When the motor electrical angle is 120-180 or 300-360, the AB bridge arm is connected in series and then connected in parallel with the C bridge arm to work. At this time, the target angle is 150 or 330.

[0024] S3. Obtain the actual rotor speed and, based on the target rotor speed, design a proportional-integral (PI) controller to control the difference in rotor speed, thereby obtaining the reference electromagnetic torque required for the rotor to move from the actual speed to the target speed. ; The speed tracking effect is as follows Figure 4 As shown in the figure, the blue solid line represents the target speed, which is derived from the difference between the target position and the actual position, while the red solid line represents the actual speed, which is directly derived from the motor. It can be seen from the figure that after 0.05s, when the position servo control starts to take effect, the actual speed is basically consistent with the target speed, indicating that the motor rotor is rotating towards the target position.

[0025] S4. Based on the real-time electrical angle of the motor in the electric drive system, the current distribution under DAB operation, and the electromagnetic torque equation, obtain the reference electromagnetic torque. With the set reference DC current The relationship is shown in equation (2), thus the reference DC current can be calculated. ; (2) In equation (2), This represents the number of pole pairs of the motor. The permanent magnet flux linkage is θ, and the rotor electrical angle is θ. Indicates the d-axis inductance. This represents the q-axis inductance.

[0026] In specific implementation, S4 The current square term in equation (2) is ignored. The reference electromagnetic torque is obtained. With reference DC component The linear relationship is obtained through linear solution. Or through external offline calculation and After establishing the mapping relationship between them, the result is obtained by looking up the table. .

[0027] S5. Design a position proportional controller P, and use... and The difference is the input to the position proportional controller P, which adjusts the proportional coefficient. Make near This outputs the duty cycle offset control value. This is used to compensate the original side bridge arm, thereby achieving servo control of the rotor position.

[0028] The AC isolated charging in this invention is achieved using DAB control. Without DAB control, a diode-based AC-to-DC conversion rectification method (uncontrolled rectification) can be used. Its advantages include low cost, simple principle, and low operational requirements. However, its output voltage is solely determined by the input AC voltage and circuit parameters, and cannot be actively adjusted by external signals. Furthermore, the diode's forward voltage drop causes losses, thus reducing charging efficiency. In contrast to uncontrolled rectification, synchronous rectification uses MOSFETs instead of diodes. By actively detecting the primary voltage signal, it precisely controls the MOSFET's on / off state, significantly reducing rectification losses and improving charging efficiency. However, it is more expensive and has stricter requirements for MOSFET switching timing; otherwise, shoot-through between the upper and lower MOSFETs may occur, leading to a short circuit.

[0029] In this embodiment, an electronic device includes a memory and a processor. The memory stores a program that supports the processor in executing the above-described method, and the processor is configured to execute the program stored in the memory.

[0030] In this embodiment, a computer-readable storage medium stores a computer program, which is executed by a processor to perform the steps of the above method.

[0031] The DC current tracking effect diagram is shown below. Figure 5 As shown in the figure, the blue solid line represents the reference DC current, and the red solid line represents the actual DC current value. Although the actual DC current value does not completely coincide with the reference value, the outline is close, indicating that current tracking has been effective. This demonstrates that the duty cycle offset obtained from the feedback P controller... That is correct, such as Figure 6 As shown, its value fluctuates around 0 after 0.05s. Since the angle that needs to be controlled is not large, the offset of the duty cycle is also small.

[0032] Figure 7The diagram shows the rotor position. Initially, the rotor is at -pi / 12. Before 0.05s, the rotor position continues to shift away from the target position. This is because the position servo control has not yet activated, and the difference in the phase average current persists, generating electromagnetic torque that causes the rotor to continue rotating in the wrong direction. After 0.05s, the rotor begins to rotate towards the target position, reaching almost the target 0 position in 0.4s, and maintaining this position after reaching it.

[0033] It can be seen that the position servo control method proposed in this invention can realize the rotor position closed loop during the DAB charging process. It can generate electromagnetic torque of different magnitudes according to different rotor positions to pull the rotor position back to the target position, solve the problem of rotor position change during charging, and effectively ensure charging efficiency.

Claims

1. A method for precise servo control of rotor position in an AC isolated charging system of an electric drive system, characterized in that: During the dual active bridge DAB control process, the reference duty cycle offset of the bridge arm is actively adjusted to generate a DC component in the AC current of the primary and secondary sides, and the electromagnetic torque generated in the motor by the DC component is used to complete the precise control of the rotor position.

2. The method for precise servo control of rotor position in an AC isolated charging electric drive system according to claim 1, characterized in that, Includes the following steps: S1. Based on the switching time of the primary or secondary bridge arm of the dual active bridge DAB in the electric drive system within one cycle, the minimum value of the primary or secondary AC current is collected in real time. With the maximum value This allows for the calculation of the DC component in the alternating current. ; S2. Obtain the actual position of the rotor in the electric drive system, and design a position proportional P controller based on the set target position of the rotor to control the difference in rotor position, thereby obtaining the target speed required for the rotor to move from the actual position to the target position. S3. Obtain the actual rotor speed and, based on the target rotor speed, design a proportional-integral (PI) controller to control the difference in rotor speed, thereby obtaining the reference electromagnetic torque required for the rotor to move from the actual speed to the target speed. ; S4. Based on the real-time electrical angle of the motor in the electric drive system, the current distribution under DAB operation, and the electromagnetic torque equation, obtain the reference electromagnetic torque. With the set reference DC current The relationship is used to calculate the reference DC current. ; S5. Design a feedback proportional controller P, and use... and The difference is the input to the feedback proportional P controller, which is used to calculate the duty cycle offset control quantity. This is used to compensate the original side bridge arm for servo control of the rotor position.

3. The rotor position precision servo control method according to claim 2, characterized in that, DC component in S1 It is calculated using equation (1): (1)。 4. The rotor position precision servo control method according to claim 2, characterized in that, Reference electromagnetic torque in S4 With reference DC current The relationship is shown in equation (2): (2) In equation (2), This represents the number of pole pairs of the motor. The permanent magnet flux linkage is θ, and the rotor electrical angle is θ. For d-axis inductance, It is the q-axis inductance.

5. The rotor position precision servo control method according to claim 2, characterized in that, The method for collecting the primary or secondary AC current in S1 is as follows: When the dual active bridge (DAB) is controlled by a single phase shift, the current value of the primary side upper arm at the turn-off moment is collected and used as the minimum value. The current value of the bridge arm on the original side at the moment of opening is collected and used as the maximum value. ; When the dual active bridge (DAB) is under dual phase-shift control or extended phase-shift control, the current value of the upper bridge arm on the primary side that has not undergone internal phase shifting at the turn-off time is collected and used as the minimum value. The current value of the lower bridge arm after internal and external phase shifts on the secondary side at the turn-off moment is collected and used as the maximum value. ; When the dual active bridge (DAB) is under triple phase-shift control, the current value of the upper bridge arm on the primary side that has not undergone the inner phase shift at the turn-off moment is collected and used as the minimum value. The current value of the upper bridge arm that has not undergone internal phase shifting at the moment of opening is collected and used as the maximum value. .

6. The rotor position precision servo control method according to claim 4, characterized in that, S4 The current square term in equation (2) is ignored. The reference electromagnetic torque is obtained. With reference DC component The linear relationship is obtained through linear solution. Or through external offline calculation and After establishing the mapping relationship between them, the result is obtained by looking up the table. .

7. The rotor position precision servo control method according to claim 2, characterized in that, The position ratio P controller adjusts the ratio coefficient. Make near This outputs the duty cycle offset control value. .

8. The rotor position precision servo control method according to claim 1, characterized in that, The AC isolated charging method based on DAB control will be replaced with an uncontrolled rectification method based on diodes, or a synchronous rectification method based on MOSFETs.

9. An electronic device, comprising a memory and a processor, characterized in that, The memory is used to store a program that supports the processor in executing the rotor position precision servo control method according to any one of claims 1-8, and the processor is configured to execute the program stored in the memory.

10. A computer-readable storage medium storing a computer program thereon, characterized in that, The computer program, when executed by the processor, performs the steps of the rotor position precise servo control method according to any one of claims 1-8.

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