Abstract: In the emergency situation of electric vehicles, the bus capacitor voltage needs to be reduced to a safe voltage as soon as possible. The traditional discharge method of bleeder resistance is large in size, high in cost, and low in reliability. To solve this problem, this paper proposed a method for discharging electric vehicle bus capacitors based on permanent magnet synchronous motor windings with the largest copper power consumption. The DC-bus capacitor discharge energy flow model based on permanent magnet synchronous motor windings as energy discharge resistance was established, and the steady-state and transient energy flow processes in the discharge process were analyzed. Through drawing the current limit circle, voltage limit ellipse and power limit circle trajectory in the dq coordinate system during the discharge process, the d-axis and q-axis currents trajectories at the maximum winding copper power consumption were obtained under the constraint condition that the electromagnetic power was less than the windings copper consumption power. Simulation and experimental results verify that this method can achieve rapid discharge of bus capacitors, eliminate the complex bleeder circuits, and improve the power density of the drive system. Compared with the traditional discharge method based on the principle of magnetic field weakening, the discharge time is shorter without DC-bus voltage surge.