Research On Model Predictive Torque Control Of Permanent Magnet Synchronous Motor System Driven By Matrix Converter

Permanent magnet synchronous motor(PMSM)has the advantages of small size,high torque inertia ratio,low loss and fast dynamic response,so it has been widely used in military and civilian fields,especially in new energy vehicles and wind power generation.Matrix converter(MC)is an AC-AC conversion topology developed in recent years.Because of the characteristics of simple structure,adjustable input power factor(PF),input current and output voltage with the shape of sine wave,and low harmonic pollution,MC is widely used in motor drives,mobile power supplies and power generation systems,which has attracted the attention of many scholars all over the world.Because PMSM is a more complex nonlinear system,this thesis uses the indirect method to analyze model predictive torque control(MPTC)of PMSM system driven by MC.Different from the existing direct MPTC methods,this thesis proposes that MC is equated into two parts as the virtual DC-AC converter and AC-DC converter.Then MPTC is proposed to select the voltage vector of the virtual DC-AC converter to reduce the torque ripple and flux pulsation,and phase hysteresis comparator is applied to select the current vector of the virtual AC-DC converter to make the PF of system input side to be 1.Different combinations of voltage vectors and current vectors make the MC in different switching states,so as to realize the control of the PMSM system.The main research content is divided into the following aspects:(1)The basic structure and switch state selection principle of MC are analyzed,and the modulation strategy of MC as a virtual AC-DC-AC converter are proposed.At the same time,the three coordinate transformations of PMSM are studied and the appropriate mathematical model is selected.(2)In order to reduce the impact of torque and flux pulsation on the PMSM system,this thesis proposes the MPTC strategy.MPTC is used to select the voltage space vector of the virtual DC-AC converter and flux pulsation,and phase hysteresis comparator is applied to select the current space vector of the virtual AC-DC converter.Based on this,MC switching state tables under different control effects are designed.(3)Aiming at the problem that the PI speed adjuster has poor control effect when the system load torque and the given speed change,an active disturbance rejection control(ADRC)speed regulator is designed by using the extended state observer and nonlinear state error feedback.Its tracking effect is studied under the condition that the load torque and the given speed change.The PMSM control system designed in this paper can effectively reduce the flux and torque ripple,improve the input side PF,and make it have better dynamic responseperformance.Applying the anti-disturbance rejection speed regulator to the system can guarantee that MC-fed PMSM possesses better command-following characteristics in the presence of variation of load torque and tracking reference speed.Finally,simulation results verify the effectiveness of the proposed strategy.