Research On Control Strategy Of TCM Inverter

As the inverter becomes lighter and smaller,the switching frequency of the device becomes higher,the inceaseing switching loss leads to the decrease of the power density and output efficiency of the inverter,which brings great challenges to the design of the inverter.In this context,this paper proposes two inverter control methods based on the triangular current mode(TCM)with the goal of optimizing efficiency.Firstly,the optimal control of non-fixed switching frequency TCM mode inverter based on hysteresis control is firstly studied.Based on the traditional BCM envelope hysteresis,the hysteresis control method of CHCM envelope and VHCM envelope is studied.The hysteresis control method of different TCM envelopes to is searched,and the switching frequency fluctuation condition and output waveform control state of the TCM mode inverter under different envelopes are compared and analyzed.The research results show that the optimal control of non-fixed switching frequency TCM mode can effectively reduce the switching frequency fluctuation and have a good control effect on the output waveform of the inverter.Secondly,this paper proposes a control study of a fixed switching frequency TCM inverter to solve the problem that the switching frequency of TCM mode is not fixed in non-fixed switching frequency TCM.The state average model is used to establish a perfect mathematical model for the inverter.The PID control method is used to realize the inverter waveform control,and the circuit analysis and LC filter parameter design are carried out.The research results show that the fixed switching frequency TCM inverter has good waveform control effect.Finally,this paper establishes a perfect mathematical model of inverter losses.Based on the mathematical model of inverter losses,the losses of the inverter in CCM and the non-fixed switching frequency TCM inverter on three different envelopes and fixed switching frequency TCM mode are calculated in order to verify the advantages of the TCM inverter in efficiency optimization.The simulation results based on Matlab/Simulink and the experimental results of the 500 W power prototype verify the significant advantages of the TCM inverter control strategy and efficiency optimization.