When a diesel locomotive or electric locomotive is braking or decelerating, the traction motor works in a power generation state, the DC bus voltage connected to the inverter rises, the brake chopper opens, and the excess energy is consumed on the brake resistor. The regenerative electric energy is directly converted into heat energy, and the regenerative electric energy will not be fed back to the power supply network, and will not cause voltage fluctuations in the power grid, thus ensuring the smooth operation of the power supply network.