A digital PFC control system design based on UCD3138

In this paper, a novel digital PFC (power factor correction) control system is introduced. For reducing the time delay during the process of current loop, the PID based filter in UCD3138 is used as the current loop PI controller. As the filter can operate independently, after configuration, it automatically exports the duty cycle. After eliminating the delay time in current loop in conventional PFC control system, higher switching frequency can be implemented. Compared to digital system based on DSP or FPGA, the cost can be then reduced, too. A hardware of digital PFC based on UCD3138 is introduced, and some experiments are carried out. The test results show that a 100kHz switching frequency can be achieved and high power factor, low THD (total harmonic distortion) and high efficiency can be obtained, which verifies the effectiveness of the digital PFC control system.