PFC with buck-boost converter

Buck-Boost converter used for Power Factor Correction (PFC) allows the output voltage to be either higher or lower than the input AC peak

Control Strategy – Two Loops

1. Outer Voltage Loop (PI Controller)

• Regulates output DC voltage
• Generates the amplitude of the current reference

2. Inner Current Loop

• Shapes input current to follow AC voltage waveform
• Can be implemented via:
• Hysteresis current control (fast, simple)
• Average current mode control (more stable)
• Peak current mode control