Totem-Pole Single-Phase PFC Zero-Crossing Leakage Current Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In totem-pole single-phase PFC converters, excessive surge currents and leakage currents cause noise and inefficiency, and existing techniques fail to sufficiently reduce leakage currents, which is a concern for preventing electric shock.
Innovation Solution
The solution involves controlling the low frequency-side node voltage into a linear shape by adjusting the duty of switching elements FETs Q1 and Q2, ensuring a constant rate of change in voltage during the Vn CTRL period, thereby reducing the peak value of leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a totem-pole single-phase PFC converter is used to improve power factor and reduce losses, then efficiency is improved, but excessive surge current flows through the inductor at zero crossing points causing noise and EMI
Solution Approach 1:
The controller performs preliminary detection of the input voltage polarity and proactively adjusts the duty ratio of switching elements before the zero crossing point is reached. This preliminary action prevents the surge current from occurring in the first place by preparing the circuit in advance for the upcoming polarity change.
Solution Approach 2:
The duty ratio of the switching elements is dynamically adjusted based on the input voltage waveform and polarity detection. The controller continuously modifies the duty ratio to maintain optimal performance while preventing surge current, making the system adaptive rather than static.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A totem-pole single-phase PFC converter which controls low frequency-side node voltage to which an inductor is not connected into a linear shape within two poles of an AC power supply at a timing where a polarity of an input to the AC power supply is reversed.