A Simple Input Filter Capacitance (IFC) Current Compensation Scheme for CRM Totem-Pole PFC With Si MOSFETs at 800 Hz Line Frequency

In critical conduction mode (CRM) totem-pole power factor correction (PFC), the leading phase of the input current caused by input filter capacitance (IFC) current deteriorates the power factor (PF) value for high line frequency (360–800 Hz) grid. In order to improve the PF, either a high-performance microprogrammed control unit (MCU) or the look-up table (LUT) method avoiding the complex cosine calculation is required for direct compensation of IFC current. However, for the purpose of matching the high frequency (360–800 Hz) input voltage and input rms voltage fluctuation ranges, the MCU with large storage capacity is needed to store the LUT data, which increases the cost. In this article, a simple IFC current compensation algorithm by low-cost commercial MCU is proposed without additional external storage components. Furthermore, in order to reduce the current distortion caused by the switching cycle negative current of the inductance, which is generated by the reverse recovery of body diode of
mosfet
and the resonance between the boost inductance and output junction capacitances of switches, a variable on-time control compensating the negative current of the inductance is proposed. With the proposed control schemes, the input current total harmonics distortion (THD) and PF can meet the RTCADO-160G Std in the high line frequency range in a 300 W CRM totem-pole PFC prototype.