Hybrid Modulation Controlled Quasi-Z Source Inverer And Application In Permanent Magnet Synchronous Motor Drive System

Permanent magnet synchronous motor has the characteristics of high efficiency,small volume and high power factor.With the development of rare earth permanent magnet materials,power electronics technology,permanent magnet motor design and manufacturing as well as microprocessing technology,the application of permanent magnet synchronous motor speed control system is becoming more and more widely.Nowadays,traditional SPWM modulation method is widely applied in Quasi-Z source inverter control system.However,the required capacitance and inductance of Quasi-Z source in traditional SPWM are large.The bulky capacitors and inductors will decrease the efficiency of the system.Therefore,in order to improve the efficiency and reduce the inductance and capacitance,hybrid modulation method based on Quasi-Z source inverter of permanent magnet synchronous motor drive system is proposed.Hybrid modulation method controlled Quasi-Z source inverter has many advantages than traditional SPWM.Hybrid modulation method reduces the switching time and switching loss of the system,thus improving the efficiency.When traditional SPWM applied,there are at least three switch devices have through vector in the zero vector,which will lead to the increase of switching frequency and loss.When hybrid modulation method is applied,in each control sector,only one bridge arm of the switches are doing switching action and other four switches are in specific states.Hybrid modulation method reduces the Quasi-Z source capacitance and inductance parameters,thus to make the system lighter and more economical.Huge capacitance and inductance of Z network are usually used when traditional SPWM applied to ensure the output quality.However,hybrid modulation method allows 6? ripple of dc bus side,thus reducing the value of passive components in Z source network.As a result,hybrid modulation method in permanent magnet synchronous motor drive system not only solves the problems above,but also has many advantages.Firstly,this thesis introduces traditional SPWM modulation method as well as its existing problems.Hybrid modulation method of Quasi-Z source in motor drive is introduced in detail.The control strategy of Quasi-Z source inverter has been analyzed and simulation results improve its validity.Secondly,compared with the traditional SPWM,Z network in hybrid modulation has lower parameters.Simulation results of two modulation methods verify that permanent magnet synchronous motor drive systemin hybrid modulation method has the same performance with the traditional SPWM.However,hybrid modulation has lower parameters.Thirdly,the detail analysis of loss calculation method in two modulation methods is given.From the loss calculation,Quasi-Z source inverter in hybrid modulation method has higher efficiency than traditional SPWM.Finally,the main power circuit and software program are designed to verify hybrid modulation method.