Devloping On AC Power Electronic Load With DC Feedback For Locomotive Power Supply Testing

Before power supply can be used in practice, they must be test for reliability and stability. Based on the locomotive DC600 V power supply testing system,electronic load made with electronic devices with energy feedback meets the testing need of AC power supply at the background of traditional electronic load’s low effects and no flexible. This paper put forward DC feedback method against the AC feedback type electronic load which is hard to control and filter. Research content is as follows:(1) The DC feedback type electronic consist of load simulation unit and DC feedback unit. This paper establish math models of two units and analizes main circuit,functions of lower machine and PC control system.(2) According to the mathematical model of load simulation units this paper establishes current single-loop discrete PI control system and calculate PI parameter by typical typeⅠsystem and typical typeⅡsystem.Because of the no static error tracking is hard for PI controller, this paper chooses proportional-resonant(PR)controller to instead PI controller and makes research on it.(3) According to the cause of the second harmonic component of the DC voltage bus, this paper makes study on it and analizes the design of the digital filter on low-pass filter, notch filter and mean filter. On the basis of current feedback unit small signal model to establish a double-loop control system voltage outer inner current loop, in accordance with best third-order system to calculate the parameters of controllers.Makes full research on the key technology of zero voltage soft switching.(4) According to the functional requirements of the system design corresponding to the main circuit of the power device parameter calculation and selection of primary circuit main components were analyzed,designed DSP and CPLD control system and sampling analog, digital input and output on zero crossing ditection circuit a critical analysis of the complete software design of part of the CPLD and DSP.(5) In MATLAB/simulink in building s-function simulation model based on the simulation results obtained to verify the feasibility of the program; to build a DC-AC electronic load feedback prototype platform, the prototype did experiments to verify the program feasibility and correctness of the theory.