Control method and system of train power supply system

The invention discloses a control method and system of a train power supply system. The control method comprises the steps that a train power supply management cabinet sends a starting signal to N train power supply units; each train power supply unit executes the following steps: an FPGA module in the train power supply unit starts timing when receiving the starting signal; a control module of each train power supply unit controls a charging contactor and a short-circuit contactor to be switched on when receiving the starting signal, and controls the charging contactor to be switched off after a first preset time TC; the FPGA module sends a switch closing command after a second preset time TS; after receiving the switch closing command, a DSP module of each train power supply unit controls the switch of the train power supply unit where the DSP module is located to be closed; and the control module controls a four-quadrant rectification module to start after the closing time of the switch reaches a third pre