Ramp assist method and system based on motor control position loop control

Abstract

The invention provides a ramp assisting method and system based on motor control position loop control, and the method comprises the following steps: S1, enabling a vehicle to enter an anti-slip mode when a preset anti-slip starting condition is met; 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; s3, motor control speed loop control is carried out, the target speed and the actual speed are input, q-axis target current and d-axis target current are output through proportional differential control, and the d-axis target current is set to be 0; the actual speed is the actual rotating speed of the permanent magnet synchronous motor; in the step S4, motor control current loop control is carried out, and three-phase voltage is output; and S5, performing motor control, inputting the three-phase voltage output in the step S4, and driving the permanent magnet synchronous motor. The control precision and the anti-interference capability can be improved, and the lag distance can be reduced or even eliminated.

Description

Technical Field

[0001] The present invention relates to the field of automobiles, and in particular to a ramp 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 advantages such as high efficiency and environmental protection. However, when a vehicle stops or starts climbing a slope, it is easy to slide down the slope due to gravity, especially on slippery roads, steep slopes or when there are vehicles behind, which may cause serious traffic safety hazards.

[0003] Existing anti-slope technology is mainly based on the fast torque response characteristics of the drive motor. By adopting the speed loop and current loop proportional integral (PI) control strategy 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 decline trend is detected to balance the vehicle's lag torque. However, the PI parameter calibration of the speed loop and the current loop is relatively complex and lengthy. Improper parameter setting can easily lead to control lag or over-control, 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 ramp 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, there is provided a hill assist method based on motor control position loop control, comprising the following steps:

[0007] Step S1, when the preset anti-slope start condition is met, the vehicle enters the anti-slope mode;

[0008] Step S2, performing motor control position loop control, inputting the target position and the 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;

[0009] Step S3, performing motor control speed loop control, inputting target speed and actual speed, and outputting q-axis target current and d-axis target current through self-disturbance rejection control, and setting the d-axis target current to 0; the actual speed is the actual speed of the permanent magnet synchronous motor; the self-disturbance rejection control estimates the disturbance situation 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 control is performed, and the actual current of the q-axis and the actual current of the d-axis are obtained and input according to the three-phase current of the permanent magnet synchronous motor, and the target current of the q-axis and the target current of the d-axis are input. Through the complex vector PI control, dynamic decoupling is achieved through zero-pole cancellation, and the q-axis voltage and the d-axis voltage are output. Then, through the inverse Park operation, the α-axis voltage and the β-axis voltage in the two-phase stationary coordinate system are output, and then the voltage signal is converted into a three-phase voltage;

[0011] In S5, the motor control is performed, 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 charging and discharging 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 slope 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 rolling judgment module is used to judge whether the vehicle meets the preset anti-slope rolling starting conditions, and when the preset anti-slope rolling starting conditions are met, the vehicle enters the anti-slope rolling 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 charging and discharging 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, make the motor stop at the specified position, and improve 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 from the detailed description of non-limiting embodiments made 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] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here 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 which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0030] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, all directional indications in this application (such as up, down, left, right, front, back, bottom...) are only used to explain the relative position relationship, movement, etc. between the components in a certain specific posture (as shown in the drawings). If the specific posture changes, the directional indication will also change accordingly.

[0031] Example 1

[0032] This embodiment provides a ramp assist method based on motor control position loop control, which can utilize the motor control position loop to input the desired rotor position information to achieve accurate control of the motor motion trajectory. The position loop receives the control signal output by the controller and transmits it to the speed loop, thereby achieving precise control of the motor 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, and is the core link of the method provided in this embodiment. First, its working principle is briefly described: a target rotor position signal is generated according to the vehicle movement requirements; the actual rotor position is collected in real time by the encoder, and the difference with the expected position is calculated to form a position error signal; the position error signal is processed by the position loop controller, and the speed control command is output to the speed loop; the speed loop converts the speed command into the 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 accurate torque output through current loop control; finally, through closed-loop linkage, the motor rotor movement is strictly followed by the expected trajectory to eliminate 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 of the system and the expected output, and adjusts the control quantity according to the proportion, integral and derivative of the deviation to achieve fast, accurate and stable system output.

[0035] Specifically, 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, when the preset anti-slope start condition is met, the vehicle enters the anti-slope mode. Furthermore, the preset anti-slope start condition can be the following conditions that are met at the same time: the vehicle is in the driving gear; the vehicle speed is less than a certain value; the battery charging and discharging capacity is normal and without faults; the motor system is normal and without overheating; the vehicle request torque is less than the actual motor torque; the road slope is greater than a certain value; the vehicle creep function is in the off state; the sensors involved in the above judgment conditions are normal and the vehicle communication is normal. When the preset anti-slope start condition is met, the anti-slope mode is entered, and the drive motor enters the zero speed mode from the torque control mode; when the preset anti-slope start condition is not met, the anti-slope mode is exited, and the motor returns to the torque control mode normally.

[0037] Furthermore, the preset anti-slope rolling start condition also includes: the actual motor speed is opposite to the current gear position, for example, the vehicle is in D gear but the motor speed is negative, and the vehicle backward rolling distance is estimated by integrating the negative change in the motor speed. If the vehicle backward rolling distance exceeds a threshold, for example, greater than or equal to 5 cm, the anti-slope rolling function is activated. Compared with conventional anti-slope rolling judgments that rely on sensors, this judgment condition does not require additional sensors, reducing the cost of the vehicle. At the same time, the algorithm directly uses motor signals to avoid misjudgments caused by sensor failures.

[0038] In step S2, the motor control position loop control is performed. If the position loop control is not introduced, and the speed loop and current loop control are relied on, when the vehicle enters the anti-slope mode, a 0 speed request is input, and after the speed loop and current loop control, the motor outputs a force opposite to the hysteresis force, so that the vehicle can achieve the hill-holding effect. However, this 0 speed control method usually introduces overshoot and oscillation of the motor speed. For the whole vehicle, the phenomenon is that the vehicle will lag and shake (similar to spring contraction). In contrast, when the position loop control is introduced, when the vehicle enters the anti-slope mode, the specific position where the rotor needs to rotate is input, and the motor can rotate to the requested position, with accurate position and strong anti-interference ability, that is, after reaching the angle, it is difficult for external force to rotate the motor, thereby achieving the 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 the target speed Speed_Ref is output through the position loop proportional control. The target position Position_Ref is the desired motor rotor position (which can be obtained and preset according to the vehicle motion requirements), and the actual position Position(θ) is the actual rotor position of the permanent magnet synchronous motor read by the encoder. The position loop control adopts proportional control (P) to ensure that the position loop control does not produce overshoot, and can achieve the effect of fast response and no overshoot. In other embodiments, the position loop control 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, 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, and the d-axis target current Id_Ref is set to 0. Among them, the actual speed ω is the actual speed of the permanent magnet synchronous motor.

[0041] Furthermore, in order to overcome the disturbance factors in the anti-slope speed loop control, such as the speed stability problem caused by the load addition and subtraction changes and the slope resistance changes, the motor control speed loop control preferably adopts the active disturbance rejection control (ADRC) control, and estimates the disturbance in real time through the extended state observer, and calculates the compensation control amount in combination with the preset compensation control strategy to perform disturbance compensation, so as to achieve accurate speed tracking.

[0042] In step S4, the motor control current loop control is performed. 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 and realizes dynamic decoupling through zero-pole cancellation. Compared with the conventional PI controller, the dynamic response is better. The complex vector PI can still maintain independent control of the dq axis current under high-speed conditions, reduce current fluctuations, realize parameter self-tuning, optimize parameters through frequency domain characteristics, reduce sensitivity to motor parameters, and improve system adaptability.

[0044] Among them, the q-axis actual current Iq and the d-axis actual current Id are obtained according to the three-phase current of the permanent magnet synchronous motor, and the acquisition method is: 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, and then the voltage signal is 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). At the same time, the position and speed information (Speed ​​& Position, including actual position θ, actual speed ω) and three-phase currents Ia, Ib, and Ic of the permanent magnet synchronous motor are obtained to realize the three-loop closed-loop control of the position loop, speed loop, and current loop.

[0047] Compared with the traditional anti-slope mode motor control entering the 0 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, and the method described in Embodiment 1 can be implemented through the cooperation between various modules. Figure 3 As shown, the present embodiment provides a slope 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 anti-slope roll judgment module is used to judge whether the vehicle meets the preset anti-slope roll start conditions. When the preset anti-slope roll start conditions are met, the vehicle enters the anti-slope roll mode. The preset anti-slope roll start conditions can be the following conditions that are met at the same time: the vehicle is in the drive gear; the vehicle speed is less than a certain value; the battery charging and discharging capacity is normal and there is no fault; the motor system is normal and there is no overheating; the vehicle request torque is less than the actual torque of the motor; the road slope is greater than a certain value; the vehicle creep function is in the off state; 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) and three-phase currents Ia, Ib, and Ic of the permanent magnet synchronous motor to achieve three-loop closed-loop control of the position loop, speed loop, and current loop.

[0052] It should be pointed out that the explanation of the implementation method and beneficial effects of a hill assist method based on motor control position loop control in Example 1 is 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 technical concept of the present invention.

Claims

1. A ramp assist method based on motor control position loop control, characterized in that: The steps include: Step S1, when the preset anti-slope start condition is met, the vehicle enters the anti-slope mode; Step S2, perform motor control position loop control, input the target position and actual position, output 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 target speed and actual speed, and outputting q-axis target current and d-axis target current through self-disturbance rejection control, and setting the d-axis target current to 0; the actual speed is the actual speed of the permanent magnet synchronous motor; the self-disturbance rejection control estimates the disturbance situation 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 control is performed, and the actual current of the q-axis and the actual current of the d-axis are obtained and input according to the three-phase current of the permanent magnet synchronous motor, and the target current of the q-axis and the target current of the d-axis are input. Through the complex vector PI control, dynamic decoupling is achieved through zero-pole cancellation, and the q-axis voltage and the d-axis voltage are output. Then, through the inverse Park operation, the α-axis voltage and the β-axis voltage in the two-phase stationary coordinate system are output, and then the voltage signal is converted into a three-phase voltage; In S5, the motor control is performed, the three-phase voltage output in step S4 is input, and the permanent magnet synchronous motor is driven.

2. A ramp assist method based on motor control position loop control as claimed in claim 1, characterized in that: The preset anti-slope start condition is 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 charging and discharging 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-slip judgment module, position loop control module, speed loop control module, current loop control module, motor control module; The anti-slope rolling judgment module is used to judge whether the vehicle meets the preset anti-slope rolling starting conditions, and when the preset anti-slope rolling starting conditions are met, the vehicle enters the anti-slope rolling 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 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. A hill assist system based on motor control position loop control as claimed in claim 3, characterized in that: The preset anti-slope start condition is to meet the following conditions at the same time: The vehicle is in the driving gear; the vehicle speed is less than a certain value; the battery charging and discharging capacity is normal and there is no fault; 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 turned off; The sensors involved in the above judgment conditions are normal and the vehicle communication is normal.

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