Development Of A New Power Electronics Experimental System With Digital-analog Hybrid Type

At present,the power electronic technology experimental equipment of domestic universities basically adopts a single analog control method,and lacks corresponding protective measures.In this thesis,the first set of new modular power electronics experimental system from open-loop control to closed-loop control,from analog control to digital control was independently developed in China,and the experimental content was progressive,the protection circuit was perfect,and the fault tolerance rate was high.Firstly,in order to improve the modeling accuracy and consider the influence of the parasitic parameters of the converter,the switching network averaging method was used to establish a non-ideal AC small signal mathematical model of the open-loop DC/DC circuit and the isolated half-bridge DC/DC circuit,and the amplitude-frequency and phase-frequency characteristics of the mathematical model were analyzed,which shows that the stability of the open-loop system is poor.In order to further improve the stability and anti-interference ability of the circuit,the corresponding closed-loop compensation parameters were designed according to the non-ideal model of the isolated half-bridge DC/DC circuit established.The rationality of the compensation parameters was verified by Saber simulation and experimental results,and the anti-interference ability and dynamic performance of the closed-loop compensation system were significantly improved.Secondly,the use of analog chips in the analog control circuit to design the corresponding circuit,although the reliability was strong,but the structure was complex and the flexibility was not good,so the DSP digital control circuit based on TMS320F28335 was added to the analog control circuit,and the advantages of simple digital control structure and strong programmability were integrated into the analog control mode.The MATLAB/PSIM model was used to automatically generate DSP code instead of manual code programming,which greatly simplified the tedious process of code programming and verified the effectiveness of automatic code generation through experiments.Finally,in order to solve the electromagnetic interference problem of the circuit system and improve the working stability of the entire circuit system,the electromagnetic interference problem of the PWM rectifier was studied and analyzed,and the electromagnetic interference suppression method of suppressing differential mode and common mode interference,cutting off the coupling path,and weakening the differential mode radiation field was proposed,and the PCB layout of the rectifier was optimized,and the interference problem was significantly improved after optimization,and can pass the EMI standard test under different switching frequencies and loads.