Research On Efficiency Characteristics Of IPM Drive System Using Quasi Z Source Inverter

The application range of permanent magnet synchronous motor(PMSM)is gradually expanded.In many cases,it is necessary for the motor to work in a wide range of speed.At this time,it is necessary to expand the speed range of PMSM.The common methods include Boost control and Flux Weakening control.The Z source converter proposed by Professor Peng Fangzheng of the Michigan State University in 2003 can realize the function of the traditional DC/DC converter.The Z source converter does not need dead band and allows shoot through state.The reliability of Z source converter is higher,and the effect of deadband is avoided.The quasi Z source converter can boost the DC bus voltage by adding the shoot through vector to realize the speed expansion.However,the loss of the inverter will increase.The traditional flux weakening control expand the speed range by increasing the direct degaussing current,and the loss of the motor will increase as the current of the motor increases.Combined the two expansion methods,the speed expansion capability and its impact on system efficiency are worth studying.The most important part of the quasi Z source IPM drive system is the quasi Z source network.On the basis of the traditional SVPWM,the DC bus voltage is adjusted by increasing the shoot through vector.In this paper,the basic principle and modulation mode of the quasi Z source converter are analyzed.Three methods are analyzed,the flux weakening control,the quasi Z source converter,the quasi Z source converter combined with flux weakening.The power loss model of the drive system is built.The speed expansion ability of the three schemes is analyzed by simulation.The speed range of the motor can be extended to a certain extent by the flux weakening control.The quasi Z source converter boost the DC bus voltage,and the speed range of motor can be expanded.The speed range of the motor can be extended further by combining the quasi Z source converter and flux weakening control.The experimental platform of the quasi Z source IPM drive system is built.According to simulation and experiment,the power loss and efficiency of the three speed expansion schemes under different working conditions are tested.The system efficiency of quasi Z source converter is highest as the speed of motor is high.The system efficiency of the quasi Z source converter combined with flux weakening control ia highest under the heavy load condition.