Research On Improved Quasi Z-Source Inverter

The inverter plays an essential role in the energy conversion and energy transfer process.The traditional voltage type inverter is buck boost inverter.In the case where the input voltage fluctuation range is large,the DC / DC converter must be increased at the front stage,which leads to the decrease of the transmission efficiency of the system.In addition,the traditional voltage type inverter does not allow the upper and lower arm to be connected at the same time otherwise it will short-circuit,damage of inverter.So the dead time must be added to the switching signal,which will cause the distortion of the output waveform.In order to overcome the shortcomings of traditional voltage source inverter,the Z source inverter is proposed.Z source inverter is a buck boost inverter with single stage structure to realize the lifting pressure.It allows both upper and lower arm to be connected simultaneously,without the dead time,significantly improving the reliability,gradually replaced the traditional voltage type inverter,and is widely used in distributed generation,motor drive system,uninterruptible power supply systems,hybrid electric vehicles.But there are many disadvantages in the Z source inverter,such as the boost ability limited,the discontinuous current,and the large capacitance voltage stress,which seriously restrict the application and development of Z source inverter.Aiming at the shortage of Z source inverter,this paper presents an improved quasi-Z-source inverter-SB/SL-q ZSI topology,analyzes its working principle,and discusses advantage of the performance of SB/SL-q ZSI compared with other Z source inverter.Through the simulation and experiment of SB/SL-q ZSI,the correctness and superiority of the novel SB/SL-q ZSI are verified.In order to overcome the disadvantage of Z source inverter modulation strategy,this paper presents a novel shoot-through segment SVPWM to minimize the inductor current ripple and compares the advantages and disadvantages of several commonly used control strategy with Z source inverter.The principle of the improved shoot-through segment SVPWM to reduce the inductance current ripple is analyzed.This paper designs the DC bus voltage closed-loop control strategy,built a small signal model of SB/SL-q ZSI and analyzes the influence of parameter values variation of capacitance and inductance of impedance network on the dynamic performance of the system.This paper analysis that SB/SL-q ZSI topology,the improved shoot-through segment SVPWM,the DC bus voltage closed-loop control strategy is applied to motor vector control.Analysis influence of the input voltage drop on the mechanical characteristics of the motor,build simulation model of the motor vector control based on SB/SL-q ZSI and to verify its effect on improving the dynamic performance of motor.