Design And Implementation Of Digital Single Phase Inverter Constant Current Source Based On FPGA

With the development of the power electronic technology,the application of the digital inverter becomes more and more popular,and the requirement of the industry is more and more strict.The output voltage of inverter power can achieve a variety of frequency,which is also very mature in the corresponding industry.However,in the part of the performance testing the voltage has no specific requirements and the current has s0.trict requirements on the testing sample,such as circuit breakers,etc.Therefore,the study of the static and dynamic characteristics of single-phase inverter constant current source becomes significant and practical value.A vector control method based on the three-phase extended equivalent circuit and the virtual circuit is proposed for the single-phase inverter constant current source.The output current of the inverter is extended to generate the other two-phase currents.Based on this extension,the current vector is synthesized.The proposed current double closed-loop control only needs to detect and control the output current without voltage.It not only can achieve good control effect,but also reduce the complexity of hardware system.The current outer-loop is to control the current vector in the dq coordinate system,and the output current can track the target value without deviation in steady state.The current inner-loop is the virtual circuit to achieve approximately decoupling and improve the dynamic response of the system by changing the inductance value.By building the simulation model in PLECS,the control system designed in this paper can meet the requirements of the output of system,and the output of the inverter can be realized without deviation in the case of switching of load.The traditional analog power has complicated hardware circuit,difficulty of debugging,and high cost of maintenance.In order to overcome the shortcomings of analog power and conform to digital control,this paper uses FPGA as the main digital chip to realize the arithmetic of SPWM.According to the technical requirements of the constant current source,this paper design the control circuit based on FPGA.Based on the experimental platform,the testing of open-loop,double-loop and double-loop switching load experiment of single-phase inverter constant current source are implemented.The results of experiment show that the control system proposed by this paper has good static and dynamic characteristics;in addition,the waveform of output current can meet the technical requirements.