Research On High Frequency Bi-directional Inverter Based On SiC Device

In the present serious shortage of energy,renewable energy represented by distribuit energy has been greatly developed,many scholars proposed the use of DC hybrid micro-grid to receive a variety of distributed powers,and bidirectional converter as a key in power conversion,its transform efficiency and reliability of the new microgrid have a significant impact.With the development of new wide band-gap silicon carbide power devices,new solutions for power electronics toward higher efficiency and power density are provided,which can simplify the topology and increase the switching frequency so as to effectively reduce the size of energy storage components,which help to reduce the size and weight of the entire system,moreover,effectively increasing system power density.The classic full-bridge topology of the bi-directional DC-AC converter has a bridge arm straight dangers,it is necessary to set a switching dead zone,moreover,body diode freewheeling losses and other issues go against for high frequency and efficiency.This paper,study a dual Buck bi-directional DC-AC converter without switching dead zone and high reliability,which can fully take advantages of the wide band-gap SiC power devices.Through the mechanism analysis method,the mathematical models in grid-connected inverter mode and rectifier PFC working mode are respectively established,and the control strategies of current loop and voltage loop are also designed.Aiming at the problems of traditional PI control algorithm such as slow response speed,incompetent to rapid track inverter current command and nonlinearity of converter.The paper designed a inner current loop controller based on model reference adaptive algorithm,then feasibility and validity of which are verified adopt simulation.Aiming at the large third harmonic of input current under rectified PFC mode,the mechanism analysis and research are carried out,and the voltage outer loop PI controller based on DC secondary voltage ripple is designed.The simulation results verify that the proposed method is effective for restraining the input current third harmonic at the same time have a faster dynamic response.Then,the parameters of the main power loop circuit of the experimental prototype with the switching frequency of 100kHz are designed.The dual-core DSP control algorithm based on TMS320F28377D is designed and the optimization of the key devices is implemented through loss calculation and analysis.For the false triggering phenomenon of SiC MOSFET in high frequency operation,the driver circuit is redesigned.Meanwhile,the influence of the circuit distribution parameters on the performance of the converter under high frequency operation has been simulated.Through the modeling and simulation analysis,the PCB circuit layout is optimized.Finally,a 1kVA experimental platform is fabricated to verify the prototype of dual Buck bi-directional inverter based on SiC power device.The results show that the designed circuit parameters are reasonable and the proposed control algorithm is feasible and effective are the same as compared with the traditional Si power device the perposed converter has greater advantages for efficiency and power density.