| With the shortage of traditional energy and the rise of the new energy,the country is vigorously developing new energy technologies to alleviate energy problems and deterioration of environmental pollution.The renewable energy converts energy into electricity through a power plan,and the three-phase inverter is the function to connect the DC energy which is generated by renewable resources such as solar energy to the grid.Therefore,the optimal design of the three-phase inverter is of great significance to the project.The physical model is constructed by theoretical analysis of the internal distribution parameters of SiC MOSFET.Then,the small-signal model at each stage of the conduction process is deduced to obtain the relationship between the corresponding drain-source current and duration.Simulated the dynamic and static characteristics of the driving voltage and operating current with the help of LTSPICE software,in order to further analyze the optimization effect of wide-band-gap semiconductor power devices to three-phase inverter.Then,the DC resonant ring is used to realize the condition that the bus voltage and current return to zero.Since the bus voltage resonance will exceed the input voltage,the active clamp DC resonance mode is needed.Combined with this soft-switching technology,the simultaneous rear-stage inverter topology and filtering structure,the small-signal model of the soft-switching inverter system in each working cycle is derived,which provides a theory for the next step of SiC MOSFET three-phase inverter simulation.By deriving the transfer function of the LCL filter and performing its bode diagram analysis,considering the amplitude spikes at the resonant frequency,the critical stability problem of the system is caused.The active damping double closed-loop control strategy is used to enhance the stability and fastness of the system.At the same time,reasonable filtering parameters are designed and the range of closed-loop PI is analyzed by the frequency domain Bode diagram and Nyquist theory criterion system,which enhances the operability of the system model.Secondly,through the PCB impedance characteristic software Si9000 simulation analysis of the drive wiring requirements and impedance matching problems at high frequencies,the parasitic effects caused by PCB layout are taken into account in the actual circuit.At the same time,based on the PLECS software platform,the loss and temperature rise of the three-phase inverter switching device under hard-switching and soft-switching are compared and analyzed,which proves the scientificity and advantages of the inverter soft-switching design.Last,2kW/220 V SiC MOSFET hard-switching and soft-switching three-phase inverters were built.In detail,the opto-coupler isolation and CMOS isolation drivers are compared,and a new high-speed drive circuit is designed to enhance the safety of the drive.Compared with the traditional hard-switching three-phase inverter,the turn-off and turn-off losses of the active clamp DC resonant three-phase inverter are reduced by 96% and 91.67%,respectively,when THD ≤ 5% is satisfied.what is more,the (94)?(9 is reduced by 5% and (9?(9 is basically unchanged,because the square of the voltage change multiplied by the junction capacitance is the amount of current change,thereby increasing the power density and reducing the system noise.Finally,by comparing the temperature rise diagrams of the SiC MOSFET and the LCL filter of the hard-switching and soft-switching three-phase inverters,it is concluded that the junction temperature of the transistor and the LCL filter under soft switching is reduced by 15 ℃ and 3℃,respectively,and the soft-switching is verified.The positive effects of technology on SiC MOSFET three-phase inverters. |
PDF Full Text Request