Diesel multiple unit and power supply system and traction control method thereof

The invention discloses a power supply system of a diesel multiple unit. The power supply system comprises an internal combustion power pack, a traction inverter, an auxiliary inverter and a supercapacitor, wherein the traction inverter and the auxiliary inverter are connected with the internal combustion power pack, the traction inverter is connected with a traction motor, the auxiliary inverter is connected with a unit load, the supercapacitor is connected with the internal combustion power pack in parallel by virtue of a direct-current chopper, and the direct-current chopper and the diesel power pack are connected with the traction inverter and the auxiliary inverter by virtue of the middle direct-current link of the traction inverter. By applying the power supply system provided by the invention, middle voltage control is simplified, and the system stability and control simplicity are enhanced. During traction, high power can be supplied by the supercapacitor within short time, so that a train is started to accelerate, and therefore, a small internal combustion power pack can be adopted, so that the size and weight of the internal combustion power pack are reduced, and the installation is facilitated. The braking renewable energy of the train can be recycled, so that the effects of energy conservation and emission reduction are achieved. Additionally, the invention further discloses the diesel multiple unit which comprises the power supply system and a traction control method of the diesel multiple unit.