Design of a Digitally Controlled Critically Continuous-Conduction Mode Boost Converter PFC (225W) – with PLD Immunity

This study aims to design a boost converter operating in the critically continuous conduction mode and has a range of 90 to 264 VAC input and regulates it to a 390V DC output. The Boost converter as an active PFC uses constant on-time for the drive pulse with a Proportional Integral compensation. Simulations show that the output voltage has an output of 384.5V with an efficiency of 97.2% and yielded a gain and phase margin of -6dB and 45°, respectively. The actual output voltage of the device is within 4% regulation and meets 96% efficiency at 220Vac input and 94% efficiency at 110Vac input. The power factor meets the requirement of at least 0.9 at minimum load of 75W. The device also complies with class A limits of Conducted Emissions EN55032, and class A limits of Harmonic Current emissions EN61000-3-2. The device is compliant with the requirements for Power Line Disturbance immunity according to EN55035. An auxiliary circuit is integrated into the circuit to allow the device to draw power from its output to power the DSP.