Abstract: The stepper motor control system is designed with DSP 2808 of TI company as its core for fulfilling the electric control of engine fuel pump rack in electric-drive mobile platform. The system achieves the engine fuel rack control by controlling the driving-pulse number of stepper motor, and a fuzzy PI control for engine speed is proposed to tackle the problem of engine speed instability caused by stepper motor fluctuation and engine nonlinearity during engine speed closed-loop control. Experimental results show that the pulses of stepper motor respond swiftly, engine speed has a good dynamic response and the output voltage of generator is stable. These provide reliable electric energy for mobile platform, meeting its requirements on engine control

Key words: engine, stepper motor, fuzzy PI control, pulse