Peak and Valley Current Control for Cuk PFC Converter to Reduce Capacitance

Traditional power factor correction (PFC) converters usually employ a large electrolytic capacitor to ensure a stiff output voltage. However, the electrolytic capacitor is not expected in terms of the reliability and the size of the system. This article proposes a peak and valley current control for Cuk PFC converter to remove the bulky electrolytic capacitor. The proposed control is realized by a combination of analog and digital circuits. The analog circuits are used to accomplish the real-time comparison between the actual currents and their reference values. And the digital circuits are employed to deal with simple logical judgement. Different from the existing full digital control technique, which needs a high-quality digital signal processor (DSP) to process complex arithmetic operation, the proposed control concept even can only require a low performance microcontroller unit. Besides, the control delay is avoided. This article first analyzes the operation stages of the Cuk PFC converter. Then, design considerations of main circuit and control circuit are introduced. Finally, the experimental results from 200W Cuk PFC converter are presented to verify the effectiveness of the proposed control.