High Power Factor CRM Boost PFC Converter With Optimum Switching Frequency Variation Range Control Based on Variable Inductor

Critical conduction-mode boost power factor correction converter with constant on -time control is widely used in low-to-medium power applications. However, the range of the switching frequency varies with different input voltages and load conditions. In this letter, a theoretical all-fixed switching frequency method based on the continuous variable inductance control is proposed first. Considering that the existing variable inductor technology is difficult to achieve a wide variation range, a switching frequency optimization compromise based on the segment variable inductance (SVI) control is put forward. Ensuring unit power factor, the proposed method significantly reduces the switching frequency variation range, which facilitates the electromagnetic interference filter design. A prototype with SVI control has been built and tested in the lab to demonstrate the validity of the proposed method.