A power supply system for vehicle control unit and method thereof

A power supply system with automatic switchover voltage for vehicle control unit is proposed. The system comprises a supply communication module configured to communicate with a vehicle control unit, the supply communication module comprising a power supply module to provide power for a vehicle control unit; and a communication device coupled to the supply communication module for showing power supply status; wherein the supply communication module provides a first direct voltage and communicates with the vehicle control unit before supplying power, and if the supply communication module does not receive any message from the vehicle control unit within a first time interval, the supply communication module automatically switches to a second direct voltage from the first direct voltage or automatically increases the first direct voltage within a second time interval, and supplies power to the vehicle control unit; and wherein the second direct voltage is greater than the first direct voltage.