Research On Control Strategy Of Z-source Inverter For High Speed Permanent Magnet Motor

With its characteristics of small volume,high power density,quiet and large system transmission efficiency,the high-speed motor has broad application in the fields of high-speed grinder,air cycle refrigeration system,high-speed power generation,fuel cell,and etcetera.And due to its excellent fault tolerance,Z-source inverter is widely used in various motor drive systems.In contrast the application of this new inverter in electrical drive systems has gradually become a research focus of improving the performance of high-speed permanent magnet motors.In traditional control methods,the DC-link voltage and output voltage control systems are designed independently,so the stability of the whole system cannot be guaranteed.However,when the high-speed permanent magnet motor operates in a wide speed range,the voltage range is extensive.The typical PI controller based control system can not meet the system requirements,so it is necessary to consider the non-linear control systems of Z-source inverter under the large-span output voltage,such as fuzzy PI controller based system,sliding mode controller based system and other control systems.At present,the research on the voltage control strategy of Z-source inverter applied to high-speed permanent magnet motor is still in its infancy,and there is no systematic research domestic and abroad.Therefore,this paper makes an in-depth study on the control strategy of Z-source inverter applied to high-speed permanent magnet motors.Firstly,the paper summarizes the working principle of high-speed permanent magnet motor and Z-source inverter,introduces several current mainstream Z-source inverter control technologies and their research status.Aiming at the full speed and full voltage range operation characteristics of high-speed permanent magnet motors,the background,and significance of the control strategy research of Z-source inverter in this paper are introduced.According to the basic principle of coordinate transformation,the mathematical model of the Z-source inverter high-speed permanent magnet motor system is obtained and analyzed.It is concluded that the control system of Z-source inverter DC-link voltage has a right half plane zero,which makes it a nonminimum phase system.It is also found that the nonlinear characteristics of the system should be considered in the selection and design of control strategies and controllers,and disturbances in the dynamic process should be compensated.Secondly,the working plane of Z-source inverter is analyzed in detail,and a control strategy of Z-source inverter for high-speed permanent magnet motor is proposed in this paper.By analyzing the target operating state of the motor and the current operation state of the Z-source inverter given by the controller,aiming at the stability and efficiency of the system,the control parameters of the Z-source inverter are obtained by functional analysis.Then the closed-loop controller is designed to make the Z-source inverter operate in the expected operation state.At the same time,because the DC-link voltage control of Z-source inverter is a non-minimum phase system,a fuzzy PI controller system and a sliding mode controller system are designed,and their stability is analyzed.Finally,an experiment platform of Z-source inverter and high-speed permanent magnet motor is set up in the laboratory,and the control system is debugged,analyzed,and verified.The experimental results show that the control strategy of Z-source inverter for high-speed permanent magnet motor described in this paper can effectively improve the stability and efficiency of motor operation.