This thesis designs a DSP-based controller which is composed of two parts,voltage controller and current controller.A proportional controller,treated as the current controller,is designed in the inner loop to control the capacitor charging current fast and effectively,especially when the sudden load is occurred.An PI controller,treated as the voltage controller,is designed in the outer loop to improve the system response irrespectively of system¡¦s parameter variation and load disturbance.The experimental result shows the output voltage can follow a sin wave which can match command exactly under the control scheme.