New energy automobile synchronous motor air-gap field oriented dead-beat current control method

Abstract

The invention discloses a new energy automobile synchronous motor air-gap field oriented dead-beat current control method. According to the method, a discrete prediction model is constructed according to a rotor flux linkage equation under a complete m-t coordinate system mathematical model of the synchronous motor, and the model describes change rules of stator voltage, stator current and excitation current in discrete time; the method further comprises a comprehensive flux linkage observer suitable for the full speed domain, delay compensation is carried out on the air gap flux linkage angle through the delay compensation technology, and the digital control delay influence is reduced. In the overall control method, the stator side of the motor adopts a dead-beat predictive current control algorithm, and the rotor side adopts dead-beat predictive duty ratio control, so that the dynamic response performance of the control system is effectively improved, and the method can realize accurate excitation current tracking and rapid dynamic response under different rotating speeds and load conditions. The overall performance of the motor control system is remarkably improved, and the motor control system is particularly suitable for new energy automobiles and other application occasions with high dynamic performance requirements.

Description

Technical Field

[0001] The invention relates to a deadbeat current control method for a motor, relates to the field of motor control, and specifically to an air gap magnetic field oriented deadbeat current control method for a synchronous motor of a new energy vehicle. Background Art

[0002] With the continuous popularization and promotion of electric vehicles in recent years, the consumption of permanent magnetic materials is huge. The electrically excited synchronous motor has been paid special attention by domestic and foreign research institutes and enterprises due to its adjustable power factor, high efficiency and strong load capacity. Therefore, the research on the control method of synchronous motor for new energy vehicles has become a key direction. The control methods of electrically excited synchronous motors are mainly divided into two categories: rotor magnetic field oriented vector control and air gap magnetic field oriented vector control. The difference lies in the choice of oriented flux. Both control methods can achieve decoupling control of torque and flux in steady state. In rotor magnetic field oriented vector control, the stator current is the torque component, and the rotor flux is controlled by the excitation current. The control is simple, but under heavy load operation conditions, the armature reaction will cause the magnetic circuit to be severely saturated, causing the motor stator voltage to increase significantly, the power factor to decrease, and the capacity of the converter to increase. Therefore, it is widely used in low-power occasions. In air gap magnetic field oriented vector control, the stator current is still the torque component, but in addition to controlling the air gap flux, the excitation current must also balance the magnetomotive force with the stator magnetomotive force. Due to this stator and rotor air gap magnetomotive force balance mechanism, the load capacity is stronger. The air-gap field-oriented vector control system of the electrically excited synchronous motor is a double 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 current loop is of great significance to the air-gap field-oriented vector control speed control system.

[0003] In traditional electrically excited synchronous motor vector control systems, PI controllers are usually used to adjust speed and current. Due to the large time constant of the rotor loop of the electrically excited synchronous motor, the flux linkage is prone to change, and the system has problems such as model errors and external load disturbances, the traditional PI control method can no longer meet the system's requirements for high dynamic performance and high robustness. In order to improve the motor control performance, it is necessary to design a current loop controller with better dynamic performance to meet the needs of actual engineering. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the present invention provides a method for controlling the air gap magnetic field of a synchronous motor of a new energy vehicle without deadbeat current. Predictive control is mainly divided into finite control set model predictive control and continuous control set model predictive control in motor control. Deadbeat Predictive Control DBPC (Deadbeat Predictive Control), as a kind of continuous control set model predictive control, originates from discrete linear state feedback control. Compared with other model predictive control methods, DBPC has the advantages of easy implementation, good dynamic performance, and small amount of calculation. The present invention is a high-performance speed regulation method for an electrically excited synchronous motor with strong robustness and high dynamic performance. The method improves the dynamic response of the system current loop, reduces the speed fluctuation of the motor during load disturbance, and improves the stability of the system.

[0005] The technical solution adopted by the present invention is:

[0006] The air gap magnetic field oriented deadbeat current control method of a synchronous motor for a new energy vehicle of the present invention comprises:

[0007] 1) 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 are obtained, and then input into the hybrid air gap flux observer based on the model reference adaptive control MRAS (Model Reference Adaptive Control) for processing and outputting the observed value of the air gap flux angle, and at the same time, the observed value of the air gap flux amplitude is obtained based on the switching control.

[0008] 2) The reference value and actual value of the speed of the electrically excited synchronous motor and the observed value and reference value of the air gap flux amplitude are subjected to speed-flux outer loop control to obtain the reference value of the T-axis stator current torque component and the reference value of the rotor excitation current in the MT coordinate system.

[0009] 3) The t-axis stator current torque component, the m-axis stator current excitation component, the reference value of the rotor excitation current, and the actual value of the rotor excitation current of the electrically excited synchronous motor are input into the zero-beat predictive current controller for stator-rotor current inner loop control. 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.

[0010] 4) The duty cycle is obtained according to the predicted value of the rotor excitation voltage of the electrically excited synchronous motor and the chopper is controlled after pulse width modulation PWM (Pulse Width Modulation), thereby controlling the rotor side of the electrically excited synchronous motor.

[0011] 5) After delay compensation, the observed value of the air gap flux linkage angle of the electrically excited synchronous motor is used together with the predicted values ​​of the m-axis and t-axis stator voltage components to control the stator side of the electrically excited synchronous motor, ultimately realizing air gap magnetic field oriented zero-beat current control of the electrically excited synchronous motor.

[0012] In the step 1), the hybrid air gap flux observer based on the model reference adaptive control MRAS constructs a synchronous motor current model and a voltage model during switching control, outputs an air gap flux amplitude observation value of the synchronous motor current model when the speed of the electrically excited synchronous motor is low, outputs an air gap flux amplitude observation value of the synchronous motor voltage model when the speed of the electrically excited synchronous motor is high, and outputs a weighted air gap flux amplitude observation value ψ of the synchronous motor current model and the voltage model when the speed of the electrically excited synchronous motor is medium. δ , as follows:

[0013]

[0014] in, and are the observed values ​​of the air gap flux amplitude output by the synchronous motor current model and voltage model respectively; i and λ u are the first and second proportional coefficients respectively; n is the actual value of the speed of the electrically excited synchronous motor, n h and n l They are respectively the upper and lower limits of the medium speed zone of the electrically excited synchronous motor.

[0015] The synchronous motor current model and voltage model are specifically as follows:

[0016] a) Synchronous motor current model:

[0017]

[0018] T d =L ad / R Dd

[0019] T q =L aq / R Dq

[0020] Among them, ψ ad and ψ aq are the d-axis and q-axis components of the air gap flux amplitude respectively; δ is the load angle; L ad and L aq are the armature reaction inductances of the d-axis and q-axis respectively; T d and T q are the time constants of the d-axis and q-axis damping windings respectively; p is the differential operator; if is the actual value of the rotor excitation current; i sd and i sq are the d-axis and q-axis stator current components respectively; R Dd and R Dq are the d-axis and q-axis damping winding resistances 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] Among them, ψ δα and ψ δβ are the α-axis and β-axis components of the air gap flux amplitude respectively; θ is the angle between the m-axis and the α-axis; u sα and u sβ are the α-axis and β-axis stator voltage components respectively; R s is the stator resistance; i sα and i sβ are the α-axis and β-axis stator current components respectively; L sl is the stator leakage inductance.

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

[0027] In the step 2), the reference value n of the speed of the electrically excited synchronous motor is * The actual value n is passed through a sliding mode controller to control the speed and obtain the reference value i of the stator current torque component of the t-axis. st * , the observed value of the air gap flux amplitude of the electrically excited synchronous motor ψ δ and the reference value ψ δ * After another sliding mode controller is used to control the air gap flux, the rotor excitation current reference value i is obtained. f * .

[0028] In the step 3), in the deadbeat predictive current controller, the reference value i of the m-axis stator excitation component of the electrically excited synchronous motor is * sm is 0, and the reference value i of the m-axis stator excitation component of the electrically excited synchronous motor at the kth moment is * sm (k), t-axis stator current torque component reference value i st * (k) and the rotor excitation current reference value i f * (k) are respectively used as the reference value i of the stator excitation component of the m-axis at the k+1th moment * sm (k+1), t-axis stator current torque component reference value i st * (k+1) and the rotor excitation current reference value i f * The predicted value of (k+1); the deadbeat prediction current controller is as follows:

[0029]

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

[0031] In the step 4), the predicted value of the duty cycle of the excitation chopper is obtained according to the predicted value of the rotor excitation voltage of the electrically excited synchronous motor, as follows:

[0032]

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

[0034] Then, pulse width modulation (PWM) is performed to obtain a pulse signal for driving the chopper switch device, thereby controlling the chopper to achieve control of the rotor side of the electrically excited synchronous motor.

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

[0036]

[0037] Among them, θ δ and θ δ * are the observed values ​​of the air gap flux angle before and after delay compensation; T s is the sampling period; ω s is the synchronous angular velocity.

[0038] In step 5), the observed value θ of the air gap flux angle after delay compensation is δ * and the m-axis stator voltage component u sm * and the t-axis stator voltage component u st * The stator side of the electrically excited synchronous motor is controlled together. Specifically, the predicted value u of the m-axis stator voltage component is firstly sm* and the predicted value u of the t-axis stator voltage component st * And the observed value of the air gap flux angle after delay compensation θ δ * After a Park transformation, the predicted value u of the α-axis stator voltage component is obtained sα * and the predicted value u of the β-axis stator voltage component sβ * , and then perform space vector pulse width modulation SVPWM (Space Vector Pulse Width Modulation) to obtain 6 PWM pulse signals, and control the converter power switching devices through the 6 PWM pulse signals, and then control the stator side of the electrically excited synchronous motor.

[0039] The beneficial effects of the present invention are:

[0040] 1. Compared with other model predictive control methods, the deadbeat predictive control method has a small amount of calculation, is easy to implement, and can converge 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 time lag in excitation current regulation.

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

[0042] 3. The present invention adopts a flux observer that combines the current model and the voltage model to achieve accurate observation of the air gap flux vector in the full speed range.

[0043] 4. The present invention adopts delay compensation technology to reduce the delay effect of the digital control system, improve the real-time control performance of the system, and enable the control system to show higher accuracy in the dynamic process.

[0044] 5. The stator current of the method of the present invention adopts beat-free predictive current control, and the excitation current adopts beat-free predictive duty cycle control, taking into account the influence of the stator current on the excitation current and the change of the load angle, and can achieve accurate excitation current tracking and fast dynamic response under different speeds and load conditions, and can accurately reflect the dynamic behavior of the electromagnetic process inside the motor. It more accurately considers the interaction between the stator current and the excitation current, as well as the change of the motor load angle, thereby greatly improving the accuracy of predictive control and the dynamic response performance, and significantly improving the overall performance of the motor control system. It is particularly suitable for applications such as new energy vehicles that have high requirements for dynamic performance. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0047] Figure 3 It is the principle diagram of the hybrid air gap flux observer of the present invention;

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

[0049] The present invention is 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 oriented deadbeat current control method for a synchronous motor of a new energy vehicle of the present invention is specifically as follows:

[0051] 1) 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 are obtained, and then input into the hybrid air gap flux observer based on the model reference adaptive control MRAS for processing and outputting 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 based on the switching control at the same time.

[0052] The hybrid air-gap flux observer based on model reference adaptive control MRAS constructs the synchronous motor current model and voltage model during switching control. When the speed of the electrically excited synchronous motor is low, it outputs the air-gap flux amplitude observation value of the synchronous motor current model. When the speed of the electrically excited synchronous motor is high, it outputs the air-gap flux amplitude observation value of 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 air-gap flux amplitude observation value ψ of the synchronous motor current model and voltage model. δ , as follows:

[0053]

[0054] in, and are the observed values ​​of the air gap flux amplitude output by the synchronous motor current model and voltage model respectively; i and λ u are the first and second proportional coefficients respectively; n is the actual value of the speed of the electrically excited synchronous motor, n h and n l They are respectively the upper and lower limits of the medium speed zone of the electrically excited synchronous motor.

[0055] Since the motor speed has a great influence on the air gap flux observation results, switching control is adopted. In order to ensure the smoothness of the air gap flux observation value, a dynamic weight adjusted according to the speed is also designed. According to the different speeds, the system dynamically adjusts the weights of the two, and accurate observation of the air gap flux can be achieved in the full speed range.

[0056] The current model and voltage model of the synchronous motor 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] Among them, ψ ad and ψ aq are the d-axis and q-axis components of the air gap flux amplitude respectively; δ is the load angle; L ad and L aq are the armature reaction inductances of the d-axis and q-axis respectively; T d and T q are the time constants of the d-axis and q-axis damping windings respectively; p is the differential operator; i f is the actual value of the rotor excitation current; i sd and i sq are the d-axis and q-axis stator current components respectively; R Dd and R Dq are the d-axis and q-axis damping winding resistances 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] Among them, ψδα and ψ δβ are the α-axis and β-axis components of the air gap flux amplitude respectively; θ is the angle between the m-axis and the α-axis; u sα and u sβ are the α-axis and β-axis stator voltage components respectively; R s is the stator resistance; i sα and i sβ are the α-axis and β-axis stator current components respectively; L sl is the stator leakage inductance.

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

[0068] 2) The reference value and actual value of the speed of the electrically excited synchronous motor and the observed value and reference value of the air gap flux amplitude are subjected to speed-flux outer loop control to obtain the reference value of the T-axis stator current torque component and the reference value of the rotor excitation current in the MT coordinate system.

[0069] The reference value n of the speed of the electrically excited synchronous motor * The actual value n is passed through a sliding mode controller to control the speed and obtain the reference value i of the stator current torque component of the t-axis. st * , the observed value of the air gap flux amplitude of the electrically excited synchronous motor ψ δ and the reference value ψ δ * After another sliding mode controller is used to control the air gap flux, the rotor excitation current reference value i is obtained. 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* and the air gap flux amplitude ψ δ * , which constitutes the reference value of the speed-flux outer loop input in the coordinated control method, the actual motor speed n is obtained by the speed position sensor, and the air gap flux observer outputs the motor air gap flux observation value ψ δ , as the feedback value of the speed-flux outer loop input, the speed and air gap flux are closed-loop controlled to obtain the stator current torque component reference value i st * and the rotor excitation current reference value i f * ; The speed-flux outer loop adopts the standard sliding mode control algorithm, as follows:

[0071]

[0072] Among them, e is the input error value; x * and x are the input reference value and feedback value respectively, x 1 and x 2 are the input error value and its differential respectively; s and are the sliding surface function and its derivative respectively; c is the design parameter of the sliding surface; ε and q are the positive first and second control parameters respectively; t 1 is the time of the integral controller; sign() is the sign function.

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

[0074] The reference value i of the m-axis stator excitation component of the electrically excited synchronous motor in the deadbeat predictive current controller * sm is 0, and the reference value i of the m-axis stator excitation component of the electrically excited synchronous motor at the kth moment is * sm (k), t-axis stator current torque component reference value i st * (k) and the rotor excitation current reference value i f * (k) are respectively used as the reference value i of the stator excitation component of the m-axis at the k+1th moment * sm (k+1), t-axis stator current torque component reference value i st *(k+1) and the rotor excitation current reference value i f * The predicted value of (k+1); the deadbeat prediction current controller is as follows:

[0075]

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

[0077] According to the d-axis stator current component i sd and the q-axis stator current component i sq And the dq axis stator voltage equation of the electrically excited synchronous motor is used to obtain the d axis stator voltage component u sd And the q-axis stator voltage component, as follows:

[0078]

[0079] Among them, ω s is the synchronous angular velocity.

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

[0081]

[0082] The deadbeat predictive current controller adopts an improved discrete prediction model constructed based on the rotor flux equation in the complete MT coordinate system, and discretizes the improved discrete model using the forward Euler method, as follows:

[0083]

[0084] Among them, u sm (k) and u st (k) are the stator voltage components of the m-axis and t-axis at the kth moment, u f (k) is the rotor excitation voltage at the kth moment; i sm (k) and i st (k) are the m-axis and t-axis components of the stator current at the kth moment, i f (k) is the excitation current at the kth moment.

[0085] The stator current of the method of the present invention adopts beat-free predictive current control, and the excitation current adopts beat-free predictive duty cycle control, taking into account the influence of the stator current on the excitation current and the change of the load angle, thereby improving the prediction accuracy and the dynamic response performance of the system; the beat-free predictive current controller describes the changes of the stator voltage, stator current and excitation current at the discrete time moment k through the MT coordinate system, can accurately reflect the dynamic behavior of the electromagnetic process inside the motor, and more accurately considers the interaction between the stator current and the excitation current, as well as the change of the motor load angle, thereby greatly improving the accuracy and dynamic performance of the predictive control.

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

[0087] The predicted value of the duty cycle of the excitation chopper is obtained according to 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 the kth moment; u f (k) is the rotor excitation voltage at the kth moment; U f_dc is the chopper DC bus voltage value.

[0090] Then, pulse width modulation (PWM) is performed to obtain a pulse signal for driving the chopper switch device, thereby controlling the chopper to achieve control of the rotor side of the electrically excited synchronous motor.

[0091] 5) After delay compensation, the observed value of the air gap flux linkage angle of the electrically excited synchronous motor is used together with the predicted values ​​of the m-axis and t-axis stator voltage components to control the stator side of the electrically excited synchronous motor, ultimately realizing air gap magnetic field oriented zero-beat current control of the electrically excited synchronous motor.

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

[0093]

[0094] Among them, θ δ and θ δ * are the observed values ​​of the air gap flux angle before and after delay compensation; T s is the sampling period; ω s is the synchronous angular velocity.

[0095] The observed value of the air gap flux angle after delay compensation is θ δ * and the m-axis stator voltage component u sm * and the t-axis stator voltage component u st * The stator side of the electrically excited synchronous motor is controlled together. Specifically, the predicted value u of the m-axis stator voltage component is firstly sm * and the predicted value u of the t-axis stator voltage component st * And the observed value of the air gap flux angle after delay compensation θ δ * After a Park transformation, the predicted value u of the α-axis stator voltage component is obtained sα * and the predicted value u of the β-axis stator voltage component sβ * , and then perform space vector pulse width modulation SVPWM to obtain 6-way PWM pulse signals, and control the converter power switching devices through the 6-way PWM pulse signals, and then control the stator side of the electrically excited synchronous motor.

[0096] The present invention adopts an improved discrete prediction model and a deadbeat prediction control strategy, taking into account the influence of stator current on excitation current and the change of load angle, thereby improving prediction accuracy, reducing control error, enhancing system stability, and improving the dynamic response performance of the electrically excited synchronous motor. Compared with the traditional PI control method, it can respond to load changes more quickly, ensure the constant operation of the air gap flux, and meet the needs of engineering applications with high requirements for dynamic performance.

[0097] Although the implementation method and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, changes 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 controlling deadbeat current of a synchronous motor of a new energy vehicle with air gap magnetic field orientation, characterized in that: include: 1) 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 are obtained, and the actual values ​​are input into the hybrid air gap flux observer based on the model reference adaptive control MRAS, and the observed value of the air gap flux angle is output after processing, and the observed value of the air gap flux amplitude is obtained based on the switching control at the same time; 2) The reference value and actual value of the speed of the electrically excited synchronous motor and the observed value and reference value of the air gap flux amplitude are subjected to speed-flux outer loop control to obtain the reference value of the t-axis stator current torque component and the reference value of the rotor excitation current in the mt coordinate system; 3) The reference value and actual value 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 are input into a deadbeat predictive current controller to perform stator-rotor current inner loop control, and the predicted values ​​of the m-axis t-axis and stator voltage components and the rotor excitation voltage are obtained; 4) Obtaining the duty cycle according to the predicted value of the rotor excitation voltage of the electrically excited synchronous motor and controlling the chopper after performing pulse width modulation (PWM), thereby controlling the rotor side of the electrically excited synchronous motor; 5) After delay compensation, the observed value of the air gap flux linkage angle of the electrically excited synchronous motor is used together with the predicted values ​​of the m-axis and t-axis stator voltage components to control the stator side of the electrically excited synchronous motor, ultimately realizing air gap magnetic field oriented zero-beat current control of the electrically excited synchronous motor.

2. The air gap magnetic field oriented deadbeat current control method for a synchronous motor of a new energy vehicle according to claim 1, characterized in that: In the step 1), the hybrid air gap flux observer based on the model reference adaptive control MRAS constructs a synchronous motor current model and a voltage model during switching control, outputs an air gap flux amplitude observation value of the synchronous motor current model when the speed of the electrically excited synchronous motor is low, outputs an air gap flux amplitude observation value of the synchronous motor voltage model when the speed of the electrically excited synchronous motor is high, and outputs a weighted air gap flux amplitude observation value ψ of the synchronous motor current model and the voltage model when the speed of the electrically excited synchronous motor is medium. δ , as follows: in, and are the observed values ​​of the air gap flux amplitude output by the synchronous motor current model and voltage model respectively; i and λ u are the first and second proportional coefficients respectively; n is the actual value of the speed of the electrically excited synchronous motor, n h and n l They are respectively the upper and lower limits of the medium speed zone of the electrically excited synchronous motor.

3. The air gap magnetic field oriented deadbeat current control method for a new energy vehicle synchronous motor according to claim 2, characterized in that: The synchronous motor current model and voltage model are specifically as follows: a) Synchronous motor current model: Among them, ψ ad and ψ aq are the d-axis and q-axis components of the air gap flux amplitude respectively; δ is the load angle; L ad and L aq are the armature reaction inductances of the d-axis and q-axis respectively; T d and T q are the time constants of the d-axis and q-axis damping windings respectively; p is the differential operator; i f is the actual value of the rotor excitation current; i sd and i sq are the d-axis and q-axis stator current components respectively; R Dd and R Dq are the d-axis and q-axis damping winding resistances respectively; b) Synchronous motor voltage model: ψ δα =∫(u sα -R s i sα )dt-L sl i sα ψ δβ =∫(u sβ -R s i sβ )dt-L sl i sβ Among them, ψ δα and ψ δβ are the α-axis and β-axis components of the air gap flux amplitude respectively; θ is the angle between the m-axis and the α-axis; u sα and u sβ are the α-axis and β-axis stator voltage components respectively; R s is the stator resistance; i sα and i sβ are the α-axis and β-axis stator current components respectively; L sl is the stator leakage inductance; α-axis stator current component i sα and the β-axis stator current component i sβ The stator a-phase current i through the electrically excited synchronous motor sa , b-phase current i sb and c-phase current i sc Transformed to the α-β two-phase stationary coordinate system, the d-axis stator current component i sd and the q-axis stator current component i sq Through the α-axis stator current component i sα and the β-axis stator current component i sβ Transform to the dq synchronous rotating coordinate system to obtain; α-axis stator voltage component u sα and the β-axis stator voltage component u sβ The stator a phase voltage u of the electrically excited synchronous motor through the electrically excited synchronous motor sa 、b phase voltage u sb and c phase voltage u sc It is obtained by transforming to the α-β two-phase stationary coordinate system.

4. The air gap magnetic field oriented deadbeat current control method for a new energy vehicle synchronous motor according to claim 1, characterized in that: In the step 2), the reference value n of the speed of the electrically excited synchronous motor is * The actual value n is passed through a sliding mode controller to control the speed and obtain the reference value i of the stator current torque component of the t-axis. st * , the observed value of the air gap flux amplitude of the electrically excited synchronous motor ψ δ and the reference value ψ δ * After another sliding mode controller is used to control the air gap flux, the rotor excitation current reference value i is obtained. f * .

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

6. The air gap magnetic field oriented deadbeat current control method for a new energy vehicle synchronous motor according to claim 1, characterized in that: In the step 4), the predicted value of the duty cycle of the excitation chopper is obtained according to the predicted value of the rotor excitation voltage of the electrically excited synchronous motor, as follows: Among them, T d * (k) is the predicted value of the duty cycle of the excitation chopper at the kth moment; u f (k) is the rotor excitation voltage at the kth moment; U f_dc is the chopper DC bus voltage value; Then, pulse width modulation (PWM) is performed to obtain a pulse signal for driving the chopper switch device, thereby controlling the chopper to achieve control of the rotor side of the electrically excited synchronous motor.

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

8. The air gap magnetic field oriented deadbeat current control method for a new energy vehicle synchronous motor according to claim 1, characterized in that: In step 5), the observed value θ of the air gap flux angle after delay compensation is δ * and the m-axis stator voltage component u sm * and the t-axis stator voltage component u st * The stator side of the electrically excited synchronous motor is controlled together. Specifically, the predicted value u of the m-axis stator voltage component is firstly sm * and the predicted value u of the t-axis stator voltage component st * And the observed value of the air gap flux angle after delay compensation θ δ * After the inverse Park transformation, the predicted value u of the α-axis stator voltage component is obtained sα * and the predicted value u of the β-axis stator voltage component sβ * , and then perform space vector pulse width modulation SVPWM to obtain 6-way PWM pulse signals, and control the converter power switching devices through the 6-way PWM pulse signals, and then control the stator side of the electrically excited synchronous motor.

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