New energy automobile synchronous motor air gap magnetic field orientation deadbeat current control method

Abstract

This invention discloses a deadbeat-free current control method for air-gap magnetic field orientation of synchronous motors in new energy vehicles. The method constructs a discrete prediction model based on the rotor flux linkage equation under a complete m-t coordinate coefficient mathematical model of the synchronous motor. This model describes the variation of stator voltage, stator current, and excitation current over discrete time. The method also includes a comprehensive flux linkage observer applicable to the entire speed range, employing delay compensation technology to compensate for the air-gap flux linkage angle, reducing the impact of digital control delays. In the overall control method, a deadbeat-free predictive current control algorithm is used on the stator side, and a deadbeat-free predictive duty cycle control is used on the rotor side, effectively improving the dynamic response performance of the control system. This method can achieve accurate excitation current tracking and rapid dynamic response under different speeds and load conditions, significantly improving the overall performance of the motor control system, and is particularly suitable for applications such as new energy vehicles with high dynamic performance requirements.

Description

Technical Field

[0001] This invention relates to a method for controlling the deadbeat current of a motor, which relates to the field of motor control, and specifically to a method for controlling the deadbeat current of a synchronous motor for a new energy vehicle with air gap magnetic field orientation. Background Technology

[0002] With the increasing popularity and promotion of electric vehicles in recent years, the consumption of permanent magnet materials has become enormous. Electrically excited synchronous motors (EMMs) have attracted significant attention from domestic and international research institutions and enterprises due to their adjustable power factor, high efficiency, and strong load-carrying capacity. Therefore, research on control methods for synchronous motors in new energy vehicles has become a key focus. The control methods for EMMs are mainly divided into two categories: rotor field-oriented vector control and air-gap field-oriented vector control. The difference lies in the selection of the directional flux linkage. Both control methods can achieve decoupling control of torque and flux linkage under steady-state conditions. In rotor field-oriented vector control, the stator current is the torque component, and the rotor flux linkage is controlled by the excitation current. This control is simple, but under heavy-load operating conditions, armature reaction can cause severe magnetic circuit saturation, leading to a significant increase in stator voltage, a decrease in power factor, and an increase in converter capacity. Therefore, it is generally used in low-power applications. In air-gap field-oriented vector control, the stator current is still the torque component, but in addition to controlling the air-gap flux linkage, the magnetomotive force of the excitation current must also be balanced with the stator magnetomotive force. Due to this stator-rotor air-gap magnetomotive force balancing mechanism, the load-carrying capacity is stronger. The air-gap magnetic field-oriented vector control system for electrically excited synchronous motors is a dual-closed-loop structure consisting of a speed-flux outer loop and a stator-rotor current inner loop. The current inner loop becomes a key factor affecting the dynamic quality of the speed control system. Therefore, improving the dynamic response of the system's current loop is of great significance for the air-gap magnetic field-oriented vector control speed control system.

[0003] In traditional vector control systems for electrically excited synchronous motors, PI controllers are typically used to regulate speed and current. However, due to the large time constant of the rotor loop in electrically excited synchronous motors, the susceptibility of flux linkage to change, and issues such as model errors and external load disturbances, traditional PI control methods can no longer meet the system's requirements for high dynamic performance and robustness. To improve motor control performance, it is necessary to design a current loop controller with better dynamic performance to meet practical engineering needs. Summary of the Invention

[0004] To address the problems existing in the background technology, this invention provides a deadbeat-predictive current control method for air-gap magnetic field orientation of synchronous motors in new energy vehicles. Predictive control in motor control is mainly divided into finite-set model predictive control and continuous-set model predictive control. Deadbeat-predictive control (DBPC), as a type of continuous-set model predictive control, originated from discrete linear state feedback control. Compared with other model predictive control methods, DBPC has advantages such as ease of implementation, good dynamic performance, and low computational complexity. This invention is a robust and high-performance speed control method for electrically excited synchronous motors. The method improves the dynamic response of the system current loop, reduces motor speed fluctuations under load disturbances, and improves system stability.

[0005] The technical solution adopted in this invention is:

[0006] The present invention provides a method for air gap magnetic field oriented deadbeat current control of a synchronous motor for new energy vehicles, comprising:

[0007] 1) Obtain the actual values ​​of the stator three-phase voltage and current and the rotor excitation current of the electrically excited synchronous motor of the new energy vehicle, and then input them into the hybrid air gap flux observer based on Model Reference Adaptive Control (MRAS) for processing and output the observed value of the air gap flux angle. At the same time, obtain the observed value of the air gap flux amplitude based on switching control.

[0008] 2) After performing speed-flux flux outer loop control on the reference and actual values ​​of the speed of the electrically excited synchronous motor and the observed and reference values ​​of the air gap flux amplitude, the reference values ​​of the stator current torque component and the rotor excitation current in the mt coordinate system are obtained.

[0009] 3) Input the reference values ​​of the t-axis stator current torque component, the m-axis stator current excitation component, and the rotor excitation current of the electrically excited synchronous motor, as well as the actual value of the rotor excitation current, into the deadbeat predictive current controller for stator-rotor current inner loop control. After processing, output the predicted values ​​of the m-axis stator voltage component, the t-axis stator voltage component, and the rotor excitation voltage.

[0010] 4) The duty cycle is obtained based on the predicted value of the rotor excitation voltage of the electrically excited synchronous motor. After pulse width modulation (PWM) is performed, the chopper is controlled, thereby controlling the rotor side of the electrically excited synchronous motor.

[0011] 5) The observed values ​​of the air gap flux linkage angle of the electrically excited synchronous motor are delayed and compensated, and then combined with the predicted values ​​of the stator voltage components of the m-axis and t-axis to control the stator side of the electrically excited synchronous motor, so as to finally realize the air gap magnetic field directional deadbeat current control of the electrically excited synchronous motor.

[0012] In step 1), the hybrid air-gap flux observer based on Model Reference Adaptive Control (MRAS) constructs a synchronous motor current model and a voltage model during switching control. When the speed of the electrically excited synchronous motor is low, it outputs the observed value of the air-gap flux amplitude from the synchronous motor current model. When the speed of the electrically excited synchronous motor is high, it outputs the observed value of the air-gap flux amplitude from the synchronous motor voltage model. When the speed of the electrically excited synchronous motor is medium, the hybrid air-gap flux observer outputs the weighted observed value ψ of the air-gap flux amplitude from the synchronous motor current model and voltage model. δ The details are as follows:

[0013]

[0014] in, and These are the observed values ​​of the air gap flux linkage amplitude output from the synchronous motor current model and voltage model, respectively; λ i and λ u These are the first and second proportional coefficients, respectively; n is the actual speed of the electrically excited synchronous motor. h and n l These represent the upper and lower limits of the medium-speed range for electrically excited synchronous motors.

[0015] The specific current and voltage models of the synchronous motor are as follows:

[0016] a) Synchronous motor current model:

[0017]

[0018] T d =L ad / R Dd

[0019] T q =L aq / R Dq

[0020] Where, ψ ad and ψ aq These represent the d-axis and q-axis components of the air gap flux linkage amplitude, respectively; δ is the load angle; L ad and L aq These are the armature reaction inductances along the d-axis and q-axis, respectively; T d and T q These are the time constants of the d-axis and q-axis damping windings, respectively; p is the differential operator; if i is the actual value of the rotor excitation current; sd and i sq These are the d-axis and q-axis stator current components, respectively; R Dd and R Dq These are the resistances of the damping windings for the d-axis and q-axis, respectively.

[0021] b) Synchronous motor voltage model:

[0022]

[0023] ψ δα =∫(u sα -R s i sα )dt-L sl i sα

[0024] ψ δβ =∫(u sβ -R s i sβ )dt-L sl i sβ

[0025] Where, ψ δα and ψ δβ These represent the α-axis and β-axis components of the air gap flux linkage amplitude, respectively; θ is the angle between the m-axis and the α-axis; u sα and u sβ These are the α-axis and β-axis stator voltage components, respectively; R s For stator resistance; i sα and i sβ These are the stator current components along the α and β axes, respectively; L sl This is due to stator leakage.

[0026] α-axis stator current component i sα and β-axis stator current component i sβ The stator phase a current i of the electrically excited synchronous motor sa b-phase current i sb and c-phase current i sc The d-axis stator current component i is obtained by transforming to the α-β two-phase stationary coordinate system. sd and q-axis stator current component i sq Through the α-axis stator current component i sα and β-axis stator current component i sβ Obtained by transforming to the dq synchronous rotating coordinate system; α-axis stator voltage component u sα and β-axis stator voltage component u sβ The stator a-phase voltage u of the electrically excited synchronous motor is... sa Phase b voltage usb and c-phase voltage u sc Obtained by transforming to the α-β two-phase stationary coordinate system.

[0027] In step 2), the reference value n of the rotational speed of the electrically excited synchronous motor is... * Together with the actual value n, the t-axis stator current torque component reference value i is obtained after speed control by a sliding mode controller. st * The observed value ψ of the air gap flux linkage amplitude of the electrically excited synchronous motor δ and reference value ψ δ * The rotor excitation current reference value i is obtained after passing through another sliding mode controller for air gap flux control. f * .

[0028] In step 3), the reference value i of the m-axis stator excitation component of the electrically excited synchronous motor in the deadbeat predictive current controller is... * sm The value is set to 0, and the reference value i of the m-axis stator excitation component of the electrically excited synchronous motor at time k is set to 0. * sm (k), Reference value of stator current torque component on the t-axis st * (k) and rotor excitation current reference value i f * (k) are used as reference values ​​i for the m-axis stator excitation components at time k+1. * sm (k+1), Reference value of stator current torque component i on the t-axis st * (k+1) and the rotor excitation current reference value i f * The predicted value of (k+1); the deadbeat predictive current controller is as follows:

[0029]

[0030] Among them, u sm * (k) and u st * (k) represents the predicted values ​​of the stator voltage components along the m-axis and t-axis at time k, respectively. f * (k) is the predicted value of the rotor excitation voltage at time k; R s For stator resistance; i sm (k) and i st (k) represent the stator current components along the m-axis and t-axis at time k; L sl For stator leakage inductance; Ts ω is the sampling period; s (k) represents the synchronous angular velocity at time k; ψ δ (k) represents the observed value of the air gap flux linkage amplitude at time k; R f i is the resistance of the excitation winding; f (k) represents the rotor excitation current at time k; L f For the excitation winding inductance; L ad δ(k) is the armature reaction inductance along the d-axis; δ(k) is the load angle at time k.

[0031] In step 4), the predicted value of the duty cycle of the excitation chopper is obtained based on the predicted value of the rotor excitation voltage of the electrically excited synchronous motor, as detailed below:

[0032]

[0033] Among them, T d * (k) is the predicted value of the duty cycle of the excitation chopper at time k; u f (k) represents the rotor excitation voltage at time k; U f_dc This represents the DC bus voltage value of the chopper.

[0034] Then, pulse width modulation (PWM) is performed to obtain the pulse signal that drives the switching devices of the chopper, thereby controlling the chopper and realizing the control of the rotor side of the electrically excited synchronous motor.

[0035] In step 5), the observed value of the air gap flux linkage angle of the electrically excited synchronous motor is compensated for a delay, thereby compensating for the deviation of the actual air gap flux linkage angle caused by the digital control delay for one control cycle, as follows:

[0036]

[0037] Where, θ δ and θ δ * These are the observed values ​​of the air gap flux linkage angle before and after time delay compensation; T s ω is the sampling period; s This refers to the synchronous angular velocity.

[0038] In step 5), the observed value θ of the air gap flux linkage angle after delay compensation is... δ * With m-axis stator voltage component u sm * and t-axis stator voltage component u st * Together, they control the stator side of the electrically excited synchronous motor. Specifically, they first control the predicted value u of the m-axis stator voltage component. sm* The predicted value of the t-axis stator voltage component u st * And the observed value θ of the air gap flux linkage angle after time delay compensation. δ * After a Parker transform, the predicted value u of the α-axis stator voltage component is obtained. sα * The predicted value of the β-axis stator voltage component u sβ * Then, Space Vector Pulse Width Modulation (SVPWM) is performed to obtain 6 PWM pulse signals, which are then used to control the power switching devices of the converter, thereby controlling the stator side of the electrically excited synchronous motor.

[0039] The beneficial effects of this invention are:

[0040] 1. Compared with other model predictive control methods, the deadbeat predictive control method has a smaller computational load, is easier to implement, and can bring the error to zero in a short time. It is suitable for practical engineering applications, has high robustness to the influence of stator current when the load changes, and effectively reduces the problem of excitation current regulation time lag.

[0041] 2. This invention improves the prediction accuracy, reduces control error, and enhances system stability by improving the discrete model to consider the influence of stator current on excitation current and the change of load angle.

[0042] 3. This invention employs a flux linkage observer that combines current and voltage models, enabling accurate observation of the air gap flux linkage vector across the entire velocity domain.

[0043] 4. This invention employs delay compensation technology, which reduces the impact of delay in the digital control system, improves the real-time control performance of the system, and enables the control system to exhibit higher precision in dynamic processes.

[0044] 5. The stator current of the method of the present invention adopts deadbeat predictive current control, and the excitation current adopts deadbeat predictive duty cycle control. It takes into account the influence of stator current on excitation current and the change of load angle, and can achieve accurate excitation current tracking and fast dynamic response under different speed and load conditions. It can accurately reflect the dynamic behavior of the electromagnetic process inside the motor, and more accurately consider the interaction between stator current and excitation current, as well as the change of motor load angle, thereby greatly improving the accuracy of predictive control and dynamic response performance, and significantly improving the overall performance of motor control system. It is particularly suitable for applications such as new energy vehicles with high dynamic performance requirements. Attached Figure Description

[0045] Figure 1 This is a control block diagram of the method of the present invention;

[0046] Figure 2 This is a vector diagram of the air gap magnetic field orientation of the present invention;

[0047] Figure 3 This is a schematic diagram of the hybrid air gap flux detector of the present invention;

[0048] Figure 4 This is a block diagram of the current inner loop control method of the present invention. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] like Figure 1 As shown, the air gap magnetic field directional deadbeat current control method for synchronous motors in new energy vehicles of the present invention is as follows:

[0051] 1) Obtain the actual values ​​of the stator three-phase voltage and current, and the rotor excitation current of the electrically excited synchronous motor of the new energy vehicle. Then, input these values ​​into a hybrid air gap flux observer based on Model Reference Adaptive Control (MRAS) for processing and output the observed value of the air gap flux angle, such as... Figure 3 As shown, the observed value of the air gap flux amplitude is obtained simultaneously based on the switching control.

[0052] The hybrid air-gap flux observer based on Model Reference Adaptive Control (MRAS) constructs synchronous motor current and voltage models during switching control. When the electrically excited synchronous motor operates at low speed, it outputs the observed air-gap flux amplitude from the synchronous motor current model. When the electrically excited synchronous motor operates at high speed, it outputs the observed air-gap flux amplitude from the synchronous motor voltage model. When the electrically excited synchronous motor operates at medium speed, the hybrid air-gap flux observer outputs the weighted observed air-gap flux amplitude ψ from the synchronous motor current and voltage models. δ The details are as follows:

[0053]

[0054] in, and These are the observed values ​​of the air gap flux linkage amplitude output from the synchronous motor current model and voltage model, respectively; λ i and λ u These are the first and second proportional coefficients, respectively; n is the actual speed of the electrically excited synchronous motor. h and n l These represent the upper and lower limits of the medium-speed range for electrically excited synchronous motors.

[0055] Since the air gap flux measurement results have a significant impact on the motor speed, switching control is adopted. To ensure the smoothness of the air gap flux measurement values, a dynamic weighting based on the speed adjustment is also designed. The system dynamically adjusts the weights of the two according to different speeds, which can achieve accurate observation of the air gap flux across the entire speed range.

[0056] The current and voltage models for synchronous motors are as follows:

[0057] a) Synchronous motor current model:

[0058]

[0059] T d =L ad / R Dd

[0060] T q =L aq / R Dq

[0061] Where, ψ ad and ψ aq These represent the d-axis and q-axis components of the air gap flux linkage amplitude, respectively; δ is the load angle; L ad and L aq These are the armature reaction inductances along the d-axis and q-axis, respectively; T d and T q These are the time constants of the d-axis and q-axis damping windings, respectively; p is the differential operator; i f i is the actual value of the rotor excitation current; sd and i sq These are the d-axis and q-axis stator current components, respectively; R Dd and R Dq These are the resistances of the damping windings for the d-axis and q-axis, respectively.

[0062] b) Synchronous motor voltage model:

[0063]

[0064] ψ δα =∫(u sα -R s i sα )dt-L sl i sα

[0065] ψ δβ =∫(u sβ -R s i sβ )dt-L sl i sβ

[0066] Where, ψδα and ψ δβ These represent the α-axis and β-axis components of the air gap flux linkage amplitude, respectively; θ is the angle between the m-axis and the α-axis; u sα and u sβ These are the α-axis and β-axis stator voltage components, respectively; R s For stator resistance; i sα and i sβ These are the stator current components along the α and β axes, respectively; L sl This is due to stator leakage.

[0067] α-axis stator current component i sα and β-axis stator current component i sβ The stator phase a current i of the electrically excited synchronous motor sa b-phase current i sb and c-phase current i sc The d-axis stator current component i is obtained by transforming to the α-β two-phase stationary coordinate system. sd and q-axis stator current component i sq Through the α-axis stator current component i sα and β-axis stator current component i sβ Obtained by transforming to the dq synchronous rotating coordinate system; α-axis stator voltage component u sα and β-axis stator voltage component u sβ The stator a-phase voltage u of the electrically excited synchronous motor is... sa Phase b voltage u sb and c-phase voltage u sc Obtained by transforming to the α-β two-phase stationary coordinate system.

[0068] 2) After performing speed-flux flux outer loop control on the reference and actual values ​​of the speed of the electrically excited synchronous motor and the observed and reference values ​​of the air gap flux amplitude, the reference values ​​of the stator current torque component and the rotor excitation current in the mt coordinate system are obtained.

[0069] The reference value n of the speed of the electrically excited synchronous motor * Together with the actual value n, the t-axis stator current torque component reference value i is obtained after speed control by a sliding mode controller. st * The observed value ψ of the air gap flux linkage amplitude of the electrically excited synchronous motor δ and reference value ψ δ * The rotor excitation current reference value i is obtained after passing through another sliding mode controller for air gap flux control. f * .

[0070] The air gap flux control error is achieved by adjusting the rotor excitation current, given the reference speed n of the electrically excited synchronous motor.* With air gap flux amplitude ψ δ * This forms the reference value for the speed-flux outer loop input in the cooperative control method. The actual motor speed n is obtained from the speed and position sensor, and the air gap flux observer outputs the observed value ψ of the motor air gap flux. δ As the feedback value of the speed-flux outer loop input, closed-loop control is performed on the speed and air gap flux to obtain the reference value i of the stator current torque component. st * With rotor excitation current reference value i f * The rotational speed and flux linkage outer loop both employ standard sliding mode control algorithms, as detailed below:

[0071]

[0072] Where e is the input error value; x * x and x' are the input reference value and feedback value, respectively; x1 and x2 are the input error value and its derivative, respectively; s and ε and q are the sliding surface function and its derivative, respectively; c is the design parameter of the sliding surface; ε and q are the first and second positive control parameters, respectively; t1 is the time of the integral controller; sign() is the sign function.

[0073] 3) The reference values ​​of the t-axis stator current torque component, the m-axis stator current excitation component, and the rotor excitation current of the electrically excited synchronous motor, along with the actual value of the rotor excitation current, are input into the deadbeat predictive current controller for stator-rotor current inner-loop control. Figure 4 As shown, after processing, the predicted values ​​of the m-axis stator voltage component, the t-axis stator voltage component, and the rotor excitation voltage are output.

[0074] In a deadbeat predictive current controller, the reference value i of the m-axis stator excitation component of an electrically excited synchronous motor is... * sm The value is set to 0, and the reference value i of the m-axis stator excitation component of the electrically excited synchronous motor at time k is set to 0. * sm (k), Reference value of stator current torque component on the t-axis st * (k) and rotor excitation current reference value i f * (k) are used as reference values ​​i for the m-axis stator excitation components at time k+1. * sm (k+1), Reference value of stator current torque component i on the t-axis st * (k+1) and the rotor excitation current reference value i f *The predicted value of (k+1); the deadbeat predictive current controller is as follows:

[0075]

[0076] Among them, u sm * (k) and u st * (k) represents the predicted values ​​of the stator voltage components along the m-axis and t-axis at time k, respectively. f * (k) is the predicted value of the rotor excitation voltage at time k; R s For stator resistance; i sm (k) and i st (k) represent the stator current components along the m-axis and t-axis at time k; L sl For stator leakage inductance; T s ω is the sampling period; s (k) represents the synchronous angular velocity at time k; ψ δ (k) represents the observed value of the air gap flux linkage amplitude at time k; R f i is the resistance of the excitation winding; f (k) represents the rotor excitation current at time k; L f For the excitation winding inductance; L ad δ(k) is the armature reaction inductance along the d-axis; δ(k) is the load angle at time k.

[0077] Based on the d-axis stator current component i sd and q-axis stator current component i sq And the d-axis stator voltage component u is obtained from the stator voltage equation of the dq-axis system of the electrically excited synchronous motor. sd The q-axis stator voltage components are as follows:

[0078]

[0079] Where, ω s This refers to the synchronous angular velocity.

[0080] like Figure 2 As shown, the air gap flux vector is further oriented along the m-axis, and the air gap flux angle observation value θ output by the air gap flux observer is used. δ The stator three-phase current i sa i sb i sc Transform to the mt synchronous rotating coordinate system to obtain the actual value i of the stator current torque component. st and the actual value of the excitation component i sm The details are as follows:

[0081]

[0082] The deadbeat predictive current controller employs an improved discrete predictive model constructed based on the rotor flux linkage equation in a complete mt coordinate system. The improved discrete model is discretized using the forward Euler method, as detailed below:

[0083]

[0084] Among them, u sm (k) and u st (k) represent the stator voltage components along the m-axis and t-axis at time k, respectively. f (k) represents the rotor excitation voltage at time k; i sm (k) and i st (k) represent the m-axis and t-axis components of the stator current at time k, respectively. f (k) represents the excitation current at time k.

[0085] The method of this invention employs deadbeat predictive current control for the stator current and deadbeat predictive duty cycle control for the excitation current. It considers the influence of stator current on excitation current and the change in load angle, thereby improving prediction accuracy and the dynamic response performance of the system. The deadbeat predictive current controller describes the changes of stator voltage, stator current, and excitation current at discrete time k using the mt coordinate system. It can accurately reflect the dynamic behavior of the electromagnetic process inside the motor and more precisely consider the interaction between stator current and excitation current, as well as the change in motor load angle, thus significantly improving the accuracy and dynamic performance of predictive control.

[0086] 4) The duty cycle is obtained based on the predicted value of the rotor excitation voltage of the electrically excited synchronous motor. After pulse width modulation (PWM) is performed, the chopper is controlled, thereby controlling the rotor side of the electrically excited synchronous motor.

[0087] The predicted duty cycle of the excitation chopper is obtained based on the predicted value of the rotor excitation voltage of the electrically excited synchronous motor, as follows:

[0088]

[0089] Among them, T d * (k) is the predicted value of the duty cycle of the excitation chopper at time k; u f (k) represents the rotor excitation voltage at time k; U f_dc This represents the DC bus voltage value of the chopper.

[0090] Then, pulse width modulation (PWM) is performed to obtain the pulse signal that drives the switching devices of the chopper, thereby controlling the chopper and realizing the control of the rotor side of the electrically excited synchronous motor.

[0091] 5) The observed values ​​of the air gap flux linkage angle of the electrically excited synchronous motor are delayed and compensated, and then combined with the predicted values ​​of the stator voltage components of the m-axis and t-axis to control the stator side of the electrically excited synchronous motor, so as to finally realize the air gap magnetic field directional deadbeat current control of the electrically excited synchronous motor.

[0092] The observed air gap flux linkage angle of the electrically excited synchronous motor is delayed and compensated for, thereby compensating for the deviation of the actual air gap flux linkage angle caused by the digital control delay for one control cycle, as follows:

[0093]

[0094] Where, θ δ and θ δ * These are the observed values ​​of the air gap flux linkage angle before and after time delay compensation; T s ω is the sampling period; s This refers to the synchronous angular velocity.

[0095] The observed value θ of the air gap flux linkage angle after time delay compensation δ * With m-axis stator voltage component u sm * and t-axis stator voltage component u st * Together, they control the stator side of the electrically excited synchronous motor. Specifically, they first control the predicted value u of the m-axis stator voltage component. sm * The predicted value of the t-axis stator voltage component u st * And the observed value θ of the air gap flux linkage angle after time delay compensation. δ * After a Parker transform, the predicted value u of the α-axis stator voltage component is obtained. sα * The predicted value of the β-axis stator voltage component u sβ * Then, space vector pulse width modulation (SVPWM) is performed to obtain 6 PWM pulse signals, which are then used to control the power switching devices of the converter, thereby controlling the stator side of the electrically excited synchronous motor.

[0096] This invention employs an improved discrete prediction model and a deadbeat-free predictive control strategy, considering the influence of stator current on excitation current and changes in load angle. This improves prediction accuracy, reduces control error, enhances system stability, and improves the dynamic response performance of the electrically excited synchronous motor. Compared to traditional PI control methods, it can respond to load changes more quickly, ensure constant air gap flux linkage, and meet the needs of engineering applications with high dynamic performance requirements.

[0097] Although the embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A method for air-gap magnetic field-oriented deadbeat current control of a synchronous motor in a new energy vehicle, characterized in that, include: 1) Obtain the actual values ​​of the stator three-phase voltage and current and the rotor excitation current of the electrically excited synchronous motor of the new energy vehicle, input them into the hybrid air gap flux observer based on model reference adaptive control (MRAS) for processing, and output the observed value of the air gap flux angle. At the same time, obtain the observed value of the air gap flux amplitude based on switching control. 2) After performing speed-flux flux outer loop control on the reference and actual values ​​of the speed of the electrically excited synchronous motor and the observed and reference values ​​of the air gap flux amplitude, the reference values ​​of the stator current torque component and the rotor excitation current in the mt coordinate system are obtained. 3) Input the reference and actual values ​​of the t-axis stator current torque component, m-axis stator current excitation component, and rotor excitation current of the electrically excited synchronous motor into the deadbeat predictive current controller for stator-rotor current inner loop control to obtain the predicted values ​​of the m-axis, t-axis, stator voltage components, and rotor excitation voltage. 4) The duty cycle is obtained based on the predicted value of the rotor excitation voltage of the electrically excited synchronous motor. After pulse width modulation (PWM) is performed, the chopper is controlled, thereby controlling the rotor side of the electrically excited synchronous motor. 5) The observed values ​​of the air gap flux linkage angle of the electrically excited synchronous motor are delayed and compensated, and then combined with the predicted values ​​of the stator voltage components of the m-axis and t-axis to control the stator side of the electrically excited synchronous motor, so as to finally realize the air gap magnetic field directional deadbeat current control of the electrically excited synchronous motor. In step 1), the hybrid air-gap flux observer based on Model Reference Adaptive Control (MRAS) constructs a synchronous motor current model and a voltage model during switching control. When the speed of the electrically excited synchronous motor is low, it outputs the observed air-gap flux amplitude of the synchronous motor current model; when the speed of the electrically excited synchronous motor is high, it outputs the observed air-gap flux amplitude of the synchronous motor voltage model; and when the speed of the electrically excited synchronous motor is medium, the hybrid air-gap flux observer outputs the weighted observed air-gap flux amplitude of the synchronous motor current model and voltage model. The details are as follows: in, and These are the observed values ​​of air gap flux linkage amplitude output from the synchronous motor current model and voltage model, respectively. and These are the first and second proportional coefficients, respectively; n is the actual speed of the electrically excited synchronous motor. and These represent the upper and lower limits of the medium-speed range for electrically excited synchronous motors. The specific current and voltage models of the synchronous motor are as follows: a) Synchronous motor current model: in, and These are the d-axis and q-axis components of the air gap flux linkage amplitude, respectively. The load angle; and These are the armature reaction inductances along the d-axis and q-axis, respectively; and These are the time constants of the d-axis and q-axis damping windings, respectively; p is the differential operator; i f This is the actual value of the rotor excitation current; and These are the stator current components along the d-axis and q-axis, respectively. and These are the resistances of the damping windings for the d-axis and q-axis, respectively. b) Synchronous motor voltage model: in, and These are the α-axis and β-axis components of the air gap flux linkage amplitude, respectively. The angle between the m-axis and the α-axis; and These are the α-axis and β-axis stator voltage components, respectively; R s Stator resistance; and These are the stator current components along the α-axis and β-axis, respectively; For stator leakage inductance; α-axis stator current components and β-axis stator current components The stator phase a current i of the electrically excited synchronous motor sa b-phase current i sb and c-phase current i sc The d-axis stator current components are obtained by transforming to the α-β two-phase stationary coordinate system. and q-axis stator current components Through the α-axis stator current component and β-axis stator current components Obtained by transforming to the dq synchronous rotating coordinate system; α-axis stator voltage component and β-axis stator voltage components The stator a-phase voltage u of the electrically excited synchronous motor is... sa Phase b voltage u sb and c-phase voltage u sc Obtained by transforming to the α-β two-phase stationary coordinate system.

2. The method for air gap magnetic field directional deadbeat current control of synchronous motors for new energy vehicles according to claim 1, characterized in that: In step 2), the reference value n of the rotational speed of the electrically excited synchronous motor is... * Together with the actual value n, the t-axis stator current torque component reference value i is obtained after speed control by a sliding mode controller. st * The observed value ψ of the air gap flux linkage amplitude of the electrically excited synchronous motor δ and reference value ψ δ * The rotor excitation current reference value i is obtained after passing through another sliding mode controller for air gap flux control. f * .

3. The air gap magnetic field directional deadbeat current control method for synchronous motors in new energy vehicles according to claim 1, characterized in that: In step 3), the reference value i of the m-axis stator excitation component of the electrically excited synchronous motor in the deadbeat predictive current controller is... * sm The value is set to 0, and the reference value i of the m-axis stator excitation component of the electrically excited synchronous motor at time k is set to 0. * sm (k), Reference value of stator current torque component on the t-axis st * (k) and rotor excitation current reference value i f * (k) are used as reference values ​​i for the m-axis stator excitation components at time k+1. * sm (k+1), Reference value of stator current torque component i on the t-axis st * (k+1) and the rotor excitation current reference value i f * The predicted value of (k+1); the deadbeat predictive current controller is as follows: Among them, u sm * (k) and u st * (k) represents the predicted values ​​of the stator voltage components along the m-axis and t-axis at time k, respectively. f * (k) is the predicted value of the rotor excitation voltage at time k; R s For stator resistance; i sm (k) and i st (k) represents the stator current components along the m-axis and t-axis at time k; For stator leakage inductance; T s ω is the sampling period; s (k) represents the synchronous angular velocity at time k; ψ δ (k) represents the observed value of the air gap flux linkage amplitude at time k; R f i is the resistance of the excitation winding; f (k) represents the rotor excitation current at time k; L f For the excitation winding inductance; The armature reactive inductance is the d-axis inductance. (k) represents the load angle at time k.

4. The method for air gap magnetic field directional deadbeat current control of synchronous motors for new energy vehicles according to claim 1, characterized in that: In step 4), the predicted value of the duty cycle of the excitation chopper is obtained based on the predicted value of the rotor excitation voltage of the electrically excited synchronous motor, as detailed below: Among them, T d * (k) is the predicted value of the duty cycle of the excitation chopper at time k; u f (k) represents the rotor excitation voltage at time k; U f_dc This is the DC bus voltage value of the chopper; Then, pulse width modulation (PWM) is performed to obtain the pulse signal that drives the switching devices of the chopper, thereby controlling the chopper and realizing the control of the rotor side of the electrically excited synchronous motor.

5. The air gap magnetic field directional deadbeat current control method for synchronous motors in new energy vehicles according to claim 1, characterized in that: In step 5), the observed value of the air gap flux linkage angle of the electrically excited synchronous motor is compensated for a time delay, as follows: Where, θ δ and θ δ * These are the observed values ​​of the air gap flux linkage angle before and after time delay compensation; T s ω is the sampling period; s This refers to the synchronous angular velocity.

6. The method for air gap magnetic field directional deadbeat current control of synchronous motors for new energy vehicles according to claim 1, characterized in that: In step 5), the observed value θ of the air gap flux linkage angle after delay compensation is... δ * With m-axis stator voltage component u sm * and t-axis stator voltage component u st * Together, they control the stator side of the electrically excited synchronous motor. Specifically, they first control the predicted value u of the m-axis stator voltage component. sm * The predicted value of the t-axis stator voltage component u st * And the observed value θ of the air gap flux linkage angle after time delay compensation. δ * The predicted values ​​of the α-axis stator voltage components are obtained after inverse Parker transformation. * Predicted values ​​of β-axis stator voltage components * Then, Space Vector Pulse Width Modulation (SVPWM) is performed to obtain 6 PWM pulse signals, which are then used to control the power switching devices of the converter, thereby controlling the stator side of the electrically excited synchronous motor.

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