| As the convertor of the electric locomotive in ac side, rectifier is one of the most important components for the whole traction and drive system. It brings harmonics pollution to the power system when adopting the traditional rectifiers which used diodes or thyristors. But it could gain higher power factor, lower harmonic distortion of the line current and bi-direction transmission of energy when we use PWM rectifier, so it has a bright future in the area of electric locomotive.The operation principle and work patterns of two level rectifier is analyzed in this paper. The equivalent circuit and mathematic model are set up by defining the ideal switch function. As it has better control performance of the transient current control strategy and predicted current control strategy, the two strategies is stated in detail in this paper. The duplicate rectifier can reduce the harmonic distortion and expand capacity, so its control strategy is researched .Compared to the two-level PWM rectifier, three-level PWM rectifier can reduce the voltage stress of the main switches and decrease harmonic distortion of the line current. In this paper, the operation principle and its equivalent circuit are illustrated of the single-phase PWM rectifier with diode-clamped topology. Several novel rectifiers are introduced, then the general mathematical model is built by defining each switch function.Transient control strategy based on SPWM and SVPWM are studied. In order to solve the inherited problem of unbalance for neutral-point voltage, a new method is proposed.Based on the analyse of theory, simulation models are built and results are given. Due to the close relation between the response characteristics and parameters of system, the way of devising single-phase voltage source PWM rectifier's main circuit parameters and the referrence expressions of parameters. The hardware platform of rectifier is built, and experimental results verify the correntness of the simulation results.
|
PDF Full Text Request