Study Of Low Floor Light Rail Vehicle Parallel Auxiliary Inverter

With the development of urban rail transit, the low floor light rail vehicle becomes more and more important in urban public transport system. As an important part of low floor light rail vehicle, the liability of the auxiliary converter is essential to the operation of the whole vehicle. In order to increase the liability of vehicle auxiliary power system, an auxiliary converter parallel scheme is proposed in the paper to increase the whole capacity and stability of low floor vehicle power system.Firstly, according to the characters of vehicle auxiliary power system, several popular converter parallel control strategies are analyzed, and advantages and disadvantages of every strategy for vehicle are get in the paper. Then an advanced strategy from master-slave strategy is proposed in the paper. The strategy carries out every converter model output phase synchronous with one synchronous pulse and achieves output voltage stable, output current equal of every converter model by voltage and circulating current feedback.Secondly, based on the proposed strategy, one converter is designed, including main circuit, control circuit and control software in the paper. Then the parallel control circuit and software is designed and the whole parallel system is built.With the main circuit, IPM is used as power device instead of IGBT, which is smaller and easier to drive. The input capacitor is selected to maintain the input DC voltage stable. And the filter capacitor and inductor is used to eliminate the harmonic and obtain good wave.The system is controlled digitally. And the main controller is TMS320F2812 DSP with CPLD. DSP generate PWM pulse and the pulse is transmitted to the power device by CPLD and other circuit to covert the DC voltage to AC by make the power device turn on and off. By detecting output voltage and current, the control system adjusts the aptitude of the AC output voltage, getting the load voltage stable and making some solution to the abnormal states such as output is overcurrent. CAN bus is applied to transmit useful information such as output current and operation state between converters to control the circulating current and operation sequence when the converters are in parallel. All in all, he controller can manage the whole system rapidly and precisely, which increases the stability and output precision of the auxiliary power system. At last, the simulation and experiment results are put forward and the feasibility of the scheme is proved, which is a reference to the low floor light rail vehicle auxiliary converter power.