Research And Implementation Of High Performance Servo Control Strategy Based On FPGA

Permanent magnet synchronous motor(PMSM)has become the preferred servo motor in the field of industrial control due to its good power density and speed regulation performance.In high performance applications,AC permanent magnet servo system usually requires fast electromagnetic torque response and strong anti-disturbance speed response without overturning,so it is difficult to achieve the control requirements by using traditional control strategy.Therefore,this paper focuses on the research of high performance servo control strategy.In this paper,the mathematical model of permanent magnet synchronous motor(PMSM)under d-q shaft-system is deduced and the space vector control technology is simply described.In order to improve the precision of electromagnetic torque control,a sigma-delta modulator and a Sinc3 filter were designed to obtain high-precision current sampling values.A high-precision vector control system model of PMSM was established based on i_d~*=0 vector control strategy.In order to reduce the system delay and increase the current loop bandwidth,a dead-beat current prediction controller is constructed based on the vector control model.Through analysis,the parameter deviation of motor model has a great influence on the stability and steady-state accuracy of the predictive control system.A Luenberger observer is proposed to observe the system disturbance and make real-time compensation,and its stability domain is defined.The PWM updating strategy is analyzed and studied.The Instant sampling instant update strategy is proposed to minimize the loop delay time of the system.Finally,the phase current distortion caused by the dead zone effect is analyzed and the adaptive dead zone compensation algorithm is used to suppress the phase current distortion.To solve the problem that PMSM is more sensitive to load torque change,PDF control is generally adopted for speed loop to improve the system’s disturbance resistance and inhibit speed overturning.However,under the traditional PDF tuning strategy,the system response time is too long.Based on the original PDF algorithm,this paper analyzes in detail the closed-loop pole position effect the dynamic performance of the system,considering the servo driver factors limit the current limiting and the hardware conditions,puts forward an improved speed loop PDF parameters setting strategy,in the guarantee system has strong resistance to interference and improve the response to the greatest extent performance.In order to solve the problem that the incremental encoder cannot obtain the initial position of the rotor,this paper adopts the pulse vibration high-frequency voltage injection method and uses the saturated salient pole effect to estimate the initial electrical Angle of the rotor.By establishing the PLL position lock-in loop mathematical model,a parameter setting method of PI phase-lock regulator is proposed,which is more intuitive and reliable than traditional empirical regulation method.Finally,based on FPGA,module design and timely sequential planning are carried out for the hardware implementation mode of control strategy,and the implementation principle of CORDIC algorithm and current vector control module is introduced in detail.Then,algorithm verification is carried out based on MATLAB/Simulink platform and the actual servo drive platform.The simulation and experimental results show that the current loop bandwidth of the permanent magnet AC servo system can reach more than 3.4KHz,the speed response can realize without overshoot tracking within 7ms and has a strong resistance to load disturbance,the rotor initial electrical Angle estimation accuracy is within±7°,and the control performance of the system is significantly improved.