Research On Three-level Active Neutral Point Clamped Converter With SiC MOSFE

Compared with two-level converters,three-level converters have attracted extensive attention due to their advantages of low device voltage stress,small dv/dt,and high output waveform quality.Active neutral point clamped(ANPC)converters not only have the advantages of general three-level converters,but also have more flexible switching modes.This paper studies the three-level ANPC converter in order to achieve the goal of high efficiency and low cost.The main contents are as follows.Firstly,the soft switching method of three-level ANPC converter was studied.Aiming at the problem of low efficiency when the switching frequency of ANPC hardswitching inverter is high,an ANPC soft-switching inverter is proposed,which enables high-frequency switching devices to realize zero voltage switching on by adding auxiliary circuits.The working principle of ANPC soft-switching inverter and the design process of each parameter are analyzed in detail;the correctness of the principle is verified by building a simulation model in MATLAB/Simulink;the experimental platform of ANPC soft-switching inverter and ANPC hard-switching inverter is built Efficiency tests are carried out and compared,and finally it is verified that the efficiency of the ANPC soft-switching inverter is higher than that of the ANPC hard-switching inverter when the switching frequency is high.Then,the dual active bridge(DAB)DC converter(referred to as TLANPC-DAB converter)constructed by ANPC three-level circuit is studied.Aiming at the problem of high cost of TLANPC-DAB converter composed of all-Si C MOSFET and low efficiency of TLANPC-DAB converter composed of all-Si IGBT,Si C MOSFET/Si IGBT hybrid TLANPC-DAB converter is proposed by making full use of the advantages of small switching loss of Si C MOSFET and low conduction loss of Si IGBT at high current and combined with a suitable control scheme.The working principle of the converter is analyzed in detail;the TLANPC-DAB converter simulation model is built in LTspice software,and the correctness of the principle is verified;the TLANPC-DAB converter experimental platform is built and the efficiency test is carried out.It is finally verified that when the converter transmits high power,the efficiency of the hybrid TLANPC-DAB converter is equivalent to that of the full Si C MOSFET TLANPC-DAB converter,but the cost of the switching devices of the converter is reduced.Finally,the switching method of the three-level ANPC converter is studied.Considering the flexibility of ANPC three-level circuit control and making full use of the respective advantages of long and short commutation loops,a low-loss switching method is proposed.A three-level ANPC converter simulation model was built in LTspice software to verify the correctness of the principle of the low-loss switching method;a double-pulse test platform was built to test the switching loss in the threelevel ANPC converter,and finally verified the proposed The low-loss switching method can effectively reduce the turn-off loss of the converter.