Research On Control Strategy Of HXD3C Electric Locomotive Auxiliary Converter System

The electric locomotive auxiliary inverter is responsible for all the auxiliary load power supply and guarantee the normal work of the auxiliary load. Its performance is very important and affects the safe and reliable operation of the electric locomotive directly. This paper analyses the control of the electric locomotive auxiliary converter based on the control system design of the HXD3C electric locomotive auxiliary converter.The HXD3C electric locomotive auxiliary converter uses ac drive system, namely AC-DC-AC structure. It is made up of two parts:the four-quadrant pulse rectifier and the inverter. The four-quadrant pulse rectifier and inverter are modeled and analyzed in this paper, and the research is mainly focused on:the mathematical model of the main circuit, working principle and control strategy of the four quadrant pulse rectifier. The four-quadrant pulse rectifier uses PI regulator to control the voltage and uses the proportional-resonant regulator to control the ac current. The inverter uses the double closed loop control strategy based on the coordinate transformation. In order to understand the proportional-resonant controller deeply, the theoretical derivation about the transfer function of the proportional-resonant controller is also presented.In view of the importance of the grid voltage synchronization signal for the control of the four quadrant pulse rectifier, various grid voltage synchronization methods are presented and compared. The PLL based on the second-order generalized integrator and its discretization methods are introduced. According to the actual situation, a PLL that can inhibit harmonics, dc component is presented and the simulation analysis is carried out. The simulation results show that the phase-locked loop is very effective.