A direct duty cycle calculation algorithm for digital power factor correction (PFC) implementation

A new PFC control method based on direct duty cycle calculation is proposed. The duty cycle required to achieve unity power factor is calculated directly based on the reference current and sensed inductor current, input voltage and output voltage. For both digital and analog implementation, the proposed PFC control method is simpler than commonly used average current mode control. Test results for a digital implementation show that the proposed method can achieve unity power factor under both steady and transient state. Sinusoidal input current can be achieved under nonsinusoidal input voltage condition. The proposed digital PFC control method can achieve good dynamic performance for load and input voltage change.