Bifurcation analysis in power factor correction converters

Abstract

Power Factor Correction (PFC) converters are widely used in industrial, commercial, aerospace and renewable energy applications. The active PFC converters are implemented to get Unity Power Factor (UPF) with low Total Harmonic Distortion (THD). These converters make the input current to have the same shape as the voltage to attain the unity power factor with tight voltage regulation. The different active PFC controllers are Peak Current Mode (PCM), Average Current Mode (ACM), Non-Linear Carrier (NLC) and General Pulse Width Modulated (GPWM) controllers. In ACM controller, the UPF operation is obtained by deriving the reference current from the sinusoidal input voltage and outer voltage loop. In NLC controller, the duty cycle is derived by comparing the non-linear carrier waveform with the switch current of the converter that forces the input current to follow the input voltage. General Pulse Width Modulation (GPWM) controller act as the resistor emulator to control the average value of the input current by modulating the duty ratio to get the UPF operation with low THD. This controller improves the stability region and it consists of the simple control circuit components like an integrator with reset switch and current sensor. newlineThe performance of the power electronic converters is affected due to non-linear behaviour and this qualitative change in converter performance due to quantitative change in system parameters is known as bifurcation. In the non-linear system, the output is extremely sensitive to initial conditions and successive occurrence of the bifurcation is known as chaos. To design the converter within the safe operating region, the study of bifurcation behaviour is essential for any application requirement. The bifurcation is also known as instability in switching converters which is classified into slow scale and fast scale instability. The fast scale instability is the period-doubling operation, which is caused by the inner current loop operation. newline