Accurate Operation Analysis Based Variable On-time Control for 360–800 Hz CRM Boost PFC Converters

The critical conduction mode (CRM) boost power factor correction (PFC) converter is widely used in low-to-medium power applications due to its low switching loss and simple control. In order to compensate the negative inductor current, variable on-time control provides a longer on-time near the zero-crossing input voltage, where the input voltage vin varies sharply especially in 360-800 Hz applications. Therefore, it is imprecise to assume that vin is constant during the switching period. Considering that vin is variable during the switching period, an accurate operation analysis is studied in this article. Moreover, a comparative analysis between the proposed accurate operation analysis and imprecise assumption-based operation analysis is conducted. Based on the operation analysis, an input filter capacitor (IFC) current compensation method is proposed to minimize the phase-leading caused by IFC current in the input current. The effectiveness of the proposed methods is verified with a 160 W gallium nitride-based CRM boost PFC converter. With the proposed methods, the input current total harmonic distortion is only 1.7% at 360 Hz input with full load and 2.42% at 800 Hz input with full load.