Optimal control for sub-unity power factor correction

This paper introduces an optimal control method for input current of a boost converter to reduce the double frequency voltage ripple at the load terminals. Using a calculus of variations method, the ideal current waveform is calculated and it is given as a reference current to a boost converter under a hysteretic control scheme. Both simulation and experimental results show a nearly 50 % reduction in capacitor size while the converter still meets IEC-61000-3-2 (class A) harmonics requirements with a power factor of 0.8 or higher. Therefore, using smaller size capacitors essentially resulted in lower cost, smaller size and higher reliability.