| Nowadays rail transport system in China plays a key important role, and Harmony CRH Electricity Multiply Units (EMU) emergence of a key role in promoting China’s railway development. With the successive operation service of Beijing-Tianjin, Wuhan-Guangzhou, and Beijing-Shanghai High Speed Railway (HSR) special for passenger transport, Chinese HSR has been developing fast. As the key technology of HSR EMU, research focused on control scheme of AC electrical traction system is significant for theory and engineering design.This paper is considering the traction converter of high-speed EMU as the research objective. Focused on the control and modulation algorithms of three-level traction converter, the theoretical research lay a solid foundation for the key technology of high speed EMU traction drive control, and provides theoretical support for the engineering design. The working principle and control method of three-level traction converter from two aspects of net side rectifier and inverter motor side link analysis.In the field of control algorithms for three-level pulse rectifier:the operation principle and mathematical modeling of single-phase three-level rectifier is discussed. On the basis of this, firstly, three-level commonly used pulse rectifier control strategy are analyzed in detail, introduces two mainstream methods to control the neutral point potential, pointed out their respective advantages and disadvantages in practice. Aiming at the voltage imbalance of three-level pulse rectifier in DC side, and discusses a suitable voltage feed-forward space vector pulse width modulation method for single-phase three-level pulse rectifier.In the field of control algorithms for three-level converter:analysis the essence of the neutral point potential fluctuation. According to the limitation in the balance control of neutral point potential in the traditional voltage space vector control, discuss a virtual space voltage vector control algorithm. By comparison, in the case of large modulation, proves that the virtual voltage vectors control the neutral point potential is fully controllable.Finally, the three-level traction converter simulation model is build up on the Matlab/Simulink, carries on the simulation research, the simulation results validate the control of neutral point potential converter. Using different control algorithms, so that the deviation of neutral point voltage is improved in different degree, the simulation results obtained, verified the correctness and effectiveness of the system control method. |
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