Bidirectional Isolation AC-DC Matrix Converter Research On Fault Protection Strategy

To improve the reliability of bidirectional isolation ac-dc matrix converter in operation,this paper analyzes the fault situation of bidirectional isolation ac-dc matrix converter and studies its corresponding protection strategy.Based on the analysis of the fault type of bidirectional isolated ac-dc matrix converter,the causes and effects of the circuit overvoltage fault and overcurrent fault are analyzed in depth,and the traditional protection method is evaluated and analyzed.On this basis,a complete set of fault protection strategies,including device level,circuit level and system level,are proposed in this paper.The device level protection requires the fastest response speed,the hardware circuit is used to protect the device directly,the buffer absorption circuit limits the voltage peak when the two ends of the device appear overvoltage,and the drive protection circuit turns off the device when the device overcurrent;The circuit level protection is realized by CPLD,the CPLD response speed is fast,the overcurrent in the circuit is protected;the system level protection timeliness requirement is the lowest,the whole operation state of the system is monitored by the DSP,The driver level protection and circuit level protection are supplemented and processed.In view of the common overcurrent faults,this paper puts forward the protection method of constructing the circuit.This method uses the non-fault device to reorganize,construct the inductance energy discharge path,release the energy on the inductor and then stop,so as to achieve the purpose of safe shutdown.The simulation model of bidirectional isolated ac-dc matrix converter overcurrent protection is built based on matlab/simulink.The simulation results are consistent with the theoretical analysis,and it is proved that the proposed method is superior to the traditional overcurrent protection method.Based on the prototype of bidirectional isolation ac-dc matrix converter,a fault protection test platform is developed,and the corresponding hardware and software design and implementation are completed.On this platform,the traditional protection method and the construction loop protection method are tested,and the results verify the feasibility and effectiveness of the proposed fault protection strategy.