UCC2818A-Q1: Voltage feedforward in PFC

Mukul Thakur

Part Number: UCC2818A-Q1
Other Parts Discussed in Thread: UCC2818

This is a block diagram of a CCM PFC. I want to understand the role of the feedforward constant block here.

This is the functional block diagram of UCC2818A-Q1. Can anyone explain how the above feedforward block is being implemented here?

over 1 year ago

0 Harish Ramakrishnan5 over 1 year ago

TI__Mastermind 21825 points

Hi Mukul,

Thank you for the query.

Consider the power delivered from rectifier, Pavg = (Vm^2/2)**k*vcontrol/Rs) where Vm is the rms value of universal input (85V to 265V) and Power can also vary from a nominal to peak values. To help the controller deal with input voltage variations we use the feedforward technique where Vcontrol is made inversely proportional to Vm^2 to remove dependency on the variation of line voltage. This is clearly explained in this video below and that is what is implemented in UCC2818.

https://www.coursera.org/learn/modeling-and-control-of-single-phase-rectifiers-and-inverters/lecture/Bj1FZ/input-voltage-feedforward-compensation

Thank you

Regards,

Harish

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UCC2818A-Q1: Voltage feedforward in PFC