Research on Three-level Rectifier Neutral-Point Voltage Balance Control in Traction Power Supply System of High Speed Train

摘要

For the neutral-point (NP) voltage balance problem of three-level PWM rectifier in high speed train traction power supply system, in this paper, a method for controlling the neutral point voltage of three level rectifier is proposed, which is based on the method of carrier amplitude conversion. By analyzing the effect of the change of the carrier amplitude on the neutral point potential, the sinusoidal pulse width modulation (SPWM) mode of the carrier amplitude transform is introduced into the control of the single phase three level pulse rectifier. The control of the neutral point voltage is achieved by the modulation of triangle carrier amplitude. Pulse conversion and carrier frequency shift are used in the control of high speed train traction and regenerative braking. At last, the Algorithm was applied to the traction condition and regenerative braking condition control of CRH2 (CHINA RAILWAY HIGH-SPEED). Compared to the transient direct current method that used in high speed train now, adding the pulse conversion and carrier amplitude shift control to the NP voltage control system have better ability to balance the NP voltage under the traction condition and regenerative braking condition. But in the condition of transform traction condition to regenerative braking condition, control method with amplitude shift is proved to be better, which illustrated the validity and superiority of carrier amplitude shift control.