High-voltage and low-voltage power-on/off time sequence control method of pure electric vehicle

The invention discloses a high-voltage and low-voltage power-on/off time sequence control method of a pure electric vehicle and belongs to the technical field of electronic control of new energy source vehicles. The high-voltage and low-voltage power-on/off time sequence control method comprises the following steps: activating KL15, enabling a VCU (Vehicle Control Unit) to be in a waiting mode from a sleeping mode and keeping for time T1; judging whether a KL15 activating state is changed or not; if the KL15 state is not changed, enabling the VCU to be in an operating mode, controlling a low-voltage controller to finish low-voltage power-on self inspection, and receiving an operating mode signal fed back by the low-voltage controller; enabling the VCU to receive the operating mode signal fed back by the low-voltage controller, and sending a high-voltage power-on request instruction to each high-voltage load controller, and sending a relay closing instruction to a BMS (Battery Management System); if the high-voltage power-on process is finished, disconnecting the KL15; enabling the VCU to be in the waiting mode from the operating mode and keeping for time T2; judging whether a KL15 disconnected state is changed or not; and if the KL15 state is not changed, enabling the VCU to control a whole vehicle power system to finish a high-voltage power-off process. By adding the waiting mode, a phenomenon that a user turns a key switch repeatedly so that a relay has a sticking fault is avoided, and thus the service life of the relay is prolonged.