Research On Mechanism And Influence Of The Rippled DC Voltage In High-speed Train Traction Drive System

In the "AC-DC-AC" traction drive system, the DC circuit is the key link between input four-quadrant convertor and output inverter. It plays a very important role in the normal operation of the traction system. In this article, two methods, steady-state theory and power balance, are used and the analysis result that the second order rippled input power is the main reason to the rippled DC voltage of the four-quadrant convertor is get. The influence of the input power and the main circuit parameters to the rippled DC voltage is been discussed. Based on the analysis result, two methods are proposed which can be used to reduce the rippled DC voltage. One is based on the theory of reducing the input rippled power, and the other is paralleling a secondary LC filter in the DC voltage of the four-quadrant convertor.The traction inverter provides VVVF three-phase AC voltage for traction motors. This paper analyses the influence of the rippled DC voltage to the output voltage of the inverter and the motors. According to analytical result, a method of the frequency compensation is been adopted to reduce the influence of the rippled DC voltage to the motor in the one-pulse control mode when the stator frequency is 100Hz. Simultaneously, the second order notch filter and low-pass filter are designed to filter the second order rippled DC voltage signal.The four-quadrant converter and traction motor control methods for high speed train are introduced in this paper. The simulation model with the control methods above and main circuit parameters of CRH2A EMUs is set up. The simulation result verifies the accuracy of the analysis. The open loop simulation model used the frequency compensation in the isochronous modulation is also set up, and the result shows the feasibility of the method.Based on the theoretical study and simulation, experimentation system has been designed. The four-quadrant convertor experiment which is under the transient direct current control has been finished. The experimental result proves the correctness of the analysis conclusion.