A ramp assist method and system based on motor control position loop control

Abstract

The present invention provides a slope assist method and system based on motor control position loop control, comprising the following steps: step S1, when a preset anti-slope start condition is met, the vehicle enters an anti-slope mode; step S2, performing motor control position loop control, inputting a target position and an actual position, and outputting a target speed through position loop proportional control; step S3, performing motor control speed loop control, inputting a target speed and an actual speed, and outputting a q-axis target current and a d-axis target current through proportional differential control, with the d-axis target current set to 0; the actual speed is the actual speed of the permanent magnet synchronous motor; in step S4, performing motor control current loop control, outputting a three-phase voltage; and in step S5, performing motor control, inputting the three-phase voltage output in step S4, and driving the permanent magnet synchronous motor. The present invention can improve control accuracy and anti-interference capability, and can reduce or even eliminate hysteresis distance.

Description

Technical Field

[0001] The present invention relates to the automotive field, and in particular to a slope assist method and system based on motor control position loop control. Background Art

[0002] With the rapid development of the new energy vehicle industry, electric drive technology has been widely used in the automotive field due to its high efficiency and environmental protection advantages. However, when a vehicle stops or starts climbing a slope, it is prone to rolling due to gravity. This is especially true on slippery roads, steep slopes, or when there are vehicles behind. This can pose a serious traffic safety hazard.

[0003] Existing anti-slope technology is mainly based on the fast torque response characteristics of the drive motor. By adopting the proportional integral (PI) control strategy of the speed loop and current loop in the motor control software, the vehicle status is monitored in real time and the braking torque is applied in the opposite direction when a slope trend is detected to balance the vehicle's lag torque. However, the calibration of the PI parameters of the speed loop and current loop is relatively complex and lengthy. Improper parameter setting can easily lead to control lag or overshoot, resulting in excessive lag distance or even the risk of loss of control. When the vehicle is fully loaded, the lag distance will be even longer. Summary of the Invention

[0004] In view of the defects in the prior art, the purpose of the present invention is to provide a slope assistance method and system based on motor control position loop control, aiming to improve control accuracy and anti-interference ability, and reduce or even eliminate lag distance.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solution:

[0006] According to a first aspect of the present invention, a hill assist method based on motor control position loop control is provided, comprising the following steps:

[0007] Step S1: When the preset anti-slope mode starting condition is met, the vehicle enters the anti-slope mode;

[0008] Step S2, performing motor control position loop control, inputting the target position and actual position, outputting the target speed through position loop proportional control; the actual position is the actual rotor position of the permanent magnet synchronous motor read by the encoder;

[0009] Step S3, performing motor control speed loop control, inputting a target speed and an actual speed, and outputting a q-axis target current and a d-axis target current through active disturbance rejection control, with the d-axis target current set to 0; the actual speed is the actual speed of the permanent magnet synchronous motor; the active disturbance rejection control estimates the disturbance in real time through an extended state observer, and calculates the compensation control amount in combination with a preset compensation control strategy to perform disturbance compensation;

[0010] In step S4, the motor control current loop is controlled. The actual q-axis current and the actual d-axis current are obtained and input according to the three-phase current of the permanent magnet synchronous motor. The q-axis target current and the d-axis target current are input. The complex vector PI control is used to achieve dynamic decoupling through zero-pole cancellation. The q-axis voltage and the d-axis voltage are output. Then, the inverse Park operation is performed to output the α-axis voltage and the β-axis voltage in the two-phase stationary coordinate system. The voltage signal is then converted into a three-phase voltage.

[0011] In S5 , the motor is controlled, the three-phase voltage output in step S4 is input, and the permanent magnet synchronous motor is driven.

[0012] Preferably, the preset anti-slope start condition is to simultaneously meet the following conditions:

[0013] The vehicle is in drive gear; the vehicle speed is less than a certain value; the battery charge and discharge capacity is normal and there are no faults; the motor system is normal and there is no overheating; the vehicle's requested torque is less than the motor's actual torque; the road slope is greater than a certain value; the vehicle's creep function is off; the sensors involved in the above judgment conditions are normal and the vehicle communication is normal.

[0014] According to a second aspect of the present invention, there is provided a hill assist system based on motor control position loop control, comprising: an anti-slip judgment module, a position loop control module, a speed loop control module, a current loop control module, and a motor control module;

[0015] The anti-slope sliding judgment module is used to judge whether the vehicle meets the preset anti-slope sliding activation conditions, and when the preset anti-slope sliding activation conditions are met, the vehicle enters the anti-slope sliding mode;

[0016] The position loop control module is used to perform motor control position loop control;

[0017] The speed loop control module is used to perform motor control speed loop control;

[0018] The current loop control module is used to perform motor control current loop control;

[0019] The motor module is used to drive the permanent magnet synchronous motor and obtain the actual position, actual speed and three-phase current of the permanent magnet synchronous motor.

[0020] Preferably, the preset anti-slope start condition is to simultaneously meet the following conditions:

[0021] The vehicle is in drive gear; the vehicle speed is less than a certain value; the battery charge and discharge capacity is normal and there are no faults; the motor system is normal and there is no overheating; the vehicle's requested torque is less than the motor's actual torque; the road slope is greater than a certain value; the vehicle's creep function is off; the sensors involved in the above judgment conditions are normal and the vehicle communication is normal.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The core of the present invention is to introduce the position loop control in the motor control, and cooperate with the speed loop and current loop control to realize three-loop closed-loop control, which can greatly improve the control accuracy of the motor, so that the motor can stop at the specified position, thereby improving the motor control accuracy, thereby reducing or even eliminating the lag distance generated when entering the anti-slip slope, and has strong anti-interference ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0025] Figure 1 Schematic diagram of the process described in Example 1;

[0026] Figure 2 Schematic diagram of the principle of the method described in Example 1;

[0027] Figure 3 Schematic diagram of the structure of the system described in Example 2. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without making any creative efforts shall fall within the scope of protection of the present application.

[0030] It should be noted that similar reference numerals and letters denote similar items in the following figures. Therefore, once an item is defined in one figure, it does not require further definition or explanation in subsequent figures. Furthermore, all directional designations (such as up, down, left, right, front, back, bottom, etc.) in this application are intended only to explain the relative positional relationships and movement of components in a specific posture (as shown in the figures). If the specific posture changes, the directional designations will also change accordingly.

[0031] Example 1

[0032] This embodiment provides a ramp assist method based on a motor-controlled position loop. The motor-controlled position loop can be used to input desired rotor position information to achieve accurate control of the motor's motion trajectory. The position loop receives control signals output by a controller and transmits them to the speed loop, thereby achieving precise control of the motor's speed and torque, ultimately ensuring that the motor can accurately move to the specified position.

[0033] The motor control position loop can accurately track and dynamically adjust the rotor position, providing the core link of the method of this embodiment. First, its working principle is briefly explained: a target rotor position signal is generated according to the vehicle movement requirements; the actual rotor position is collected in real time by an encoder, and the difference between it and the desired position is calculated to form a position error signal; after the position error signal is processed by the position loop controller, a speed control command is output to the speed loop; the speed loop converts the speed command into a motor drive current, drives the motor to generate the corresponding torque, and continuously monitors the actual speed and compares it with the target value, and realizes precise torque output through current loop control; finally, through closed-loop linkage, the motor rotor movement strictly follows the desired trajectory, eliminating the displacement deviation caused by slope slip.

[0034] In addition, a brief description of the PID control principle is given. PID control, which is the abbreviation of proportional, integral and derivative control, is a control strategy widely used in process control. It calculates the deviation between the actual output and the expected output of the system, and adjusts the control quantity according to the proportion, integral and derivative of this deviation to achieve fast, accurate and stable system output.

[0035] Specifically, if Figure 1 、 Figure 2 As shown, the slope assist method based on motor control position loop control provided in this embodiment includes the following steps.

[0036] In step S1, the vehicle enters hill-roll prevention mode when the preset hill-roll prevention activation conditions are met. Furthermore, the preset hill-roll prevention activation conditions can be the simultaneous fulfillment of the following conditions: the vehicle is in drive gear; the vehicle speed is less than a certain value; the battery charge and discharge capacity is normal and fault-free; the motor system is normal and not overheating; the vehicle's requested torque is less than the motor's actual torque; the road slope is greater than a certain value; the vehicle's creep function is disabled; and the sensors involved in the above judgment conditions are normal and vehicle communications are normal. When the preset hill-roll prevention activation conditions are met, the vehicle enters hill-roll prevention mode, and the drive motor switches from torque control mode to zero speed mode. When the preset hill-roll prevention activation conditions are not met, the vehicle exits hill-roll prevention mode, and the motor returns to torque control mode normally.

[0037] Furthermore, the preset hill-roll prevention activation condition also includes: when the actual motor speed is opposite to the current gear position, for example, when the vehicle is in D gear but the motor speed is negative, the vehicle's backward roll distance is estimated by integrating the negative change in motor speed. If the backward roll distance exceeds a threshold, for example, greater than or equal to 5 cm, the hill-roll prevention function is activated. Compared to conventional hill-roll prevention judgments that rely on sensors, this judgment condition does not require additional sensors, reducing vehicle costs. Furthermore, the algorithm directly utilizes motor signals, avoiding misjudgments caused by sensor failures.

[0038] In step S2, the motor is controlled by a position loop. If position loop control is not introduced and the vehicle relies on speed and current loop control, when the vehicle enters anti-slope mode and a 0 speed request is input, the motor outputs a force opposite to the hysteresis force after speed and current loop control, thereby achieving a hill-holding effect. However, this 0 speed control method often introduces overshoot and oscillation in the motor speed, which results in hysteresis and jitter (similar to a spring contraction) for the entire vehicle. In contrast, when position loop control is introduced, when the vehicle enters anti-slope mode and a specific position for the rotor to rotate is input, the motor can rotate to the requested position with accuracy and strong anti-interference capabilities. That is, after reaching the desired angle, it is difficult for external forces to rotate the motor, thus achieving a hill-holding effect.

[0039] Specifically, the position loop control adopts proportional control (P), such as Figure 2 As shown, the target position Position_Ref and the actual position Position(θ) are input, and through position loop proportional control, the target speed Speed_Ref is output. The target position Position_Ref is the desired motor rotor position (which can be obtained and preset based on vehicle motion requirements), and the actual position Position(θ) is the actual rotor position of the permanent magnet synchronous motor read by the encoder. Using proportional control (P) in the position loop ensures that the position loop does not overshoot and achieves a fast response without overshoot. In other embodiments, the position loop can also adopt proportional differential control (PD) or proportional integral control (PI).

[0040] In step S3, the motor control speed loop is controlled. Figure 2 As shown in the figure, the target speed Speed_Ref and the actual speed ω are input, and the q-axis target current Iq_Ref and the d-axis target current Id_Ref are output through proportional differential control. The d-axis target current Id_Ref is set to 0. The actual speed ω is the actual speed of the permanent magnet synchronous motor.

[0041] Furthermore, to overcome disturbances in the anti-slope speed loop control, such as speed stability issues caused by changes in load addition and subtraction and slope resistance, the motor control speed loop preferably uses active disturbance rejection control (ADRC) control. This uses an extended state observer to estimate disturbances in real time and, combined with a preset compensation control strategy, calculates the compensation control variable to perform disturbance compensation, achieving precise speed tracking.

[0042] In step S4, the motor control current loop is controlled. Figure 2 As shown, the q-axis target current Iq_Ref and the d-axis target current Id_Ref, the q-axis actual current Iq and the d-axis actual current Id are input, and the q-axis voltage Vq and the d-axis voltage Vd are output through proportional differential control.

[0043] Furthermore, the current loop adopts complex vector PI control, which achieves dynamic decoupling through zero-pole cancellation. Compared with conventional PI controllers, it has better dynamic response. The complex vector PI can still maintain independent control of the dq axis current under high-speed conditions, reduce current fluctuations, achieve parameter self-tuning, optimize parameters through frequency domain characteristics, reduce sensitivity to motor parameters, and improve system adaptability.

[0044] The q-axis actual current Iq and the d-axis actual current Id are obtained based on the three-phase currents of the permanent magnet synchronous motor. The acquisition method is as follows: obtain the three-phase currents Ia, Ib, and Ic of the permanent magnet synchronous motor, generate the α-axis current Iα and the β-axis current Iβ through Clark transformation, and then generate the q-axis actual current Iq and the d-axis actual current Id through Park transformation.

[0045] Then, through the inverse Park operation (RevPark transformation), the α-axis voltage Vα and β-axis voltage Vβ in the two-phase stationary coordinate system (α-β coordinate system) are output according to the q-axis voltage Vq and the d-axis voltage Vd. The voltage signal is then converted into three-phase voltages Va, Vb, and Vc through SVPMW (space vector pulse width modulation).

[0046] In S5, the motor control is performed. Figure 2 As shown, the three-phase voltages Va, Vb, and Vc output in step S4 are input to drive the permanent magnet synchronous motor (PMSM). Simultaneously, the position and speed information (Speed ​​& Position, including actual position θ and actual speed ω) and three-phase currents Ia, Ib, and Ic of the PMSM are obtained to implement closed-loop control of the position loop, speed loop, and current loop.

[0047] Compared with the traditional anti-slope mode motor control entering the zero speed control mode, the method provided in this embodiment introduces position loop control and coordinates with speed loop and current loop control to achieve three-loop closed-loop control, which can greatly improve the control accuracy of the motor, thereby reducing or even eliminating the lag distance generated when entering the anti-slope mode.

[0048] Example 2

[0049] This embodiment provides a hill assist system based on motor control position loop control, which can realize the method described in Example 1 through the cooperation between various modules. Figure 3 As shown, this embodiment provides a hill assist system based on motor control position loop control, including: an anti-slip judgment module, a position loop control module, a speed loop control module, a current loop control module, and a motor control module.

[0050] The hill-slide prevention judgment module is used to determine whether the vehicle meets the preset hill-slide prevention activation conditions. If the preset hill-slide prevention activation conditions are met, the vehicle enters the hill-slide prevention mode. The preset hill-slide prevention activation conditions can be the following: the vehicle is in drive gear; the vehicle speed is less than a certain value; the battery charge and discharge capacity is normal and there are no faults; the motor system is normal and there is no overtemperature; the vehicle's requested torque is less than the actual motor torque; the road slope is greater than a certain value; the vehicle's creep function is disabled; and the sensors involved in the above judgment conditions are normal and the vehicle communication is normal.

[0051] The position loop control module is used to perform motor control position loop control; the speed loop control module is used to perform motor control speed loop control; the current loop control module is used to perform motor control current loop control; the motor module is used to drive the permanent magnet synchronous motor and obtain the position and speed information (Speed ​​& Position, including actual position θ, actual speed ω) of the permanent magnet synchronous motor, and the three-phase currents Ia, Ib, and Ic to achieve three-loop closed-loop control of the position loop, speed loop, and current loop.

[0052] It should be noted that the explanation of the implementation method and beneficial effects of a hill assist method based on motor-controlled position loop control in Example 1 are also applicable to the system provided in this embodiment and will not be repeated here.

[0053] The above describes the specific embodiments of the present invention. Based on the above description, relevant personnel can make various changes and modifications without departing from the scope of the technical concept of this invention.

Claims

1. A slope assist method based on motor control position loop control, characterized in that: The steps include: Step S1: When the preset anti-slope mode starting condition is met, the vehicle enters the anti-slope mode; Step S2, performing motor control position loop control, inputting the target position and actual position, and outputting the target speed through position loop proportional control; The actual position is the actual rotor position of the permanent magnet synchronous motor read by the encoder; Step S3, performing motor control speed loop control, inputting a target speed and an actual speed, and outputting a q-axis target current and a d-axis target current through active disturbance rejection control, with the d-axis target current set to 0; the actual speed is the actual speed of the permanent magnet synchronous motor; the active disturbance rejection control estimates the disturbance in real time through an extended state observer, and calculates the compensation control amount in combination with a preset compensation control strategy to perform disturbance compensation; In step S4, the motor control current loop is controlled. The actual q-axis current and the actual d-axis current are obtained and input according to the three-phase current of the permanent magnet synchronous motor. The q-axis target current and the d-axis target current are input. The complex vector PI control is used to achieve dynamic decoupling through zero-pole cancellation. The q-axis voltage and the d-axis voltage are output. Then, the inverse Park operation is performed to output the α-axis voltage and the β-axis voltage in the two-phase stationary coordinate system. The voltage signal is then converted into a three-phase voltage. In S5 , the motor is controlled, the three-phase voltage output in step S4 is input, and the permanent magnet synchronous motor is driven.

2. The method for hill assist based on motor control position loop control according to claim 1, characterized in that: The preset anti-slope start-up conditions are to meet the following conditions at the same time: The vehicle is in drive gear; the vehicle speed is less than a certain value; the battery charge and discharge capacity is normal and there are no faults; the motor system is normal and there is no overheating; the vehicle's requested torque is less than the motor's actual torque; the road slope is greater than a certain value; the vehicle's creep function is off; the sensors involved in the above judgment conditions are normal and the vehicle communication is normal.

3. A hill assist system based on motor control position loop control, characterized in that: include: Anti-slope judgment module, position loop control module, speed loop control module, current loop control module, motor control module; The anti-slope sliding judgment module is used to judge whether the vehicle meets the preset anti-slope sliding activation conditions, and when the preset anti-slope sliding activation conditions are met, the vehicle enters the anti-slope sliding mode; The position loop control module is used to perform motor control position loop control; The speed loop control module is used to perform motor control speed loop control; The current loop control module is used to perform motor control current loop control; The motor control module is used to drive the permanent magnet synchronous motor and obtain the actual position, actual speed and three-phase current of the permanent magnet synchronous motor.

4. The hill assist system based on motor control position loop control according to claim 3, characterized in that: The preset anti-slope start-up conditions are to meet the following conditions at the same time: The vehicle is in drive gear; the vehicle speed is less than a certain value; the battery charge and discharge capacity is normal and there are no faults; the motor system is normal and there is no overtemperature; the vehicle's requested torque is less than the motor's actual torque; the road slope is greater than a certain value; the vehicle's creep function is off; The sensors involved in the above judgment conditions are normal and the vehicle communication is normal.

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