Bridgeless PFC Circuit TCM Control Eliminates Reverse Recovery Losses
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Solution Overview
Problem
Existing bridgeless PFC circuits experience uncontrollable reverse recovery currents, which affect the soft switching state of switching components and hinder efficient operation, especially at high input voltages.
Innovation Solution
A bridgeless PFC circuit employing a Triangular Current Mode (TCM) control method, where the control module detects and turns off a switching component only when a negative current flows, eliminating reverse recovery current losses and enabling zero voltage switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional bridge PFC circuit is used, then the circuit structure is complete with multiple conduction devices, but the on-state loss is large and efficiency is reduced
Solution Approach 1:
The patent removes the bridge structure (rectifier bridge and filter capacitor) from the conventional PFC circuit, extracting only the essential inductor and switching components. This extraction eliminates unnecessary conduction devices and reduces on-state loss while maintaining the core power factor correction function through a simplified topology.
2Loss of energy
If a bridgeless PFC circuit with CRM control is used, then the on-state loss is reduced, but uncontrollable reverse recovery current affects soft switching state
Solution Approach 1:
The patent implements a feedback control mechanism that monitors the current flowing through the switching component and uses this information to control the turn-off timing. The control module detects the current direction and adjusts the switching timing accordingly, creating a closed-loop system that ensures reliable soft switching while eliminating reverse recovery current issues.
Solution Approach 2:
The patent transitions from a static CRM control mode to a dynamic TCM control mode where the switching timing is continuously adjusted based on real-time current detection. This dynamic adaptation allows the circuit to maintain optimal soft switching performance across varying operating conditions while eliminating the reverse recovery current problem.
3Loss of energy
If CRM control is used where switching component turns off when inductive current approaches zero, then zero voltage switching is implemented, but reverse recovery current of body diode becomes uncontrollable
Solution Approach 1:
The patent replaces the passive CRM control mechanism (relying on natural current zero-crossing and body diode reverse recovery) with an active control system using a control module that electronically detects current direction and precisely controls switching timing. This substitution eliminates the uncontrollable reverse recovery current while maintaining ease of operation through automated electronic control.
Data Source
AI summary
A bridgeless power factor correction (PFC) circuit, which includes an alternating current power supply module, a power module, and a control module; the power module includes one or more interleaved PFC circuits, each interleaved PFC circuit includes one inductor, one pair of first switching components, and at least one capacitor, a first end of the inductor is connected to the alternating current power supply module, and a second end of the inductor is connected to one end of each capacitor through one of the first switching components and is also connected to the other end of each capacitor through the other one of the first switching components; and the control module samples a current of each first switching component in the power module, and turns off a first switching component through which a negative current flows.