PCH And Backstepping Adaptive Control Of Permanent Magnet Synchronous Motor Based On Back-to-back Converter

The permanent magnet synchronous motor(PMSM)drive system based on back to back converter has many advantages,such as the controllable DC bus voltage,the power factor can be arbitrarily configured,four quadrant operation of motor and bidirectional energy flow.Therefore,it is widely used in industrial drive fields.As we known,PMSM is a kind of nonlinear system with high accuracy,strong coupling and variable parameters.The four quadrant PMSM drive system composed of back to back converter and permanent magnet synchronous motor,and the traditional control strategy can only basically meet the control objectives of the four quadrant PMSM drive system.In order to improve the performance of the system,this thesis based on the signal control and energy control,designed the signal controller based on backstepping and adaptive control and the energy controller based on PCH respectively,the performance of the design scheme is verifies through the simulation results.The further analyzes whether the design scheme has better performance by comparing the Voltage Oriented Control on the grid side and the Field Oriented Control on the motor side.Firstly,the development history of four quadrant permanent magnet synchronous motor drive system at home and abroad is introduced.The control strategy of independent control on grid side,independent control on motor side and the coordinated control on grid side and motor side are mainly introduced.Secondly,the basic structure and working principle of four quadrant permanent magnet synchronous motor drive system are introduced.The relationship between the energy flow direction and the working state of the converter is analyzed.Finally,the mathematical models of the grid side subsystem and the motor side subsystem in different coordinate systems are derived and established.Thirdly,based on the classical vector control,the control strategies of Voltage Oriented Control on the grid side and Field Oriented Control on the motor side are designed.The performance of the design scheme is verified based on MATLAB.The results show that the design scheme can basically meet the control objectives of the four quadrant permanent magnet synchronous motor drive system,but there are some problems,such as the bus voltage is easy to fluctuate and the motor speed tracking is not accurate.Fourthly,from the point of view of signal control,on the basis of backstepping control,adaptive control is introduced to further weaken the influence of uncertain factors on the performance of the design scheme.A load torque observer is designed to solve the problem of unknown load torque.The load current flowing to the motor side is fed back to the grid side,strengthening the coordination control between the grid side and the motor side.The simulation results show that the load torque observer can estimate the real-time load torque very well.Compared with the design scheme in Chapter three,the dynamic performance of backstepping adaptive control designed in this chapter is better.Fifthly,from the point of view of energy control,the PCH controllers on the grid side and motor side are designed respectively,and the load torque observer designed in Chapter four is cited.The simulation results show that,compared with the control strategies of Voltage Oriented Control on grid side and Field Oriented Control on motor side,under the PCH control designed in this chapter,the DC bus voltage stability is better and the motor speed tracking effect is better.To sum up,the permanent magnet synchronous motor four quadrant drive system based on Back-to-Back converter is taken as the control object,the backstepping adaptive controller designed in this study accelerates the response speed of the DC bus voltage and motor speed,and improves the dynamic performance of the permanent magnet synchronous motor four quadrant drive system;the PCH controller designed enhances the stability of the DC bus voltage and improves the static performance of the system.