Totem-Pole PFC Switching Control for Accurate ZVS Timing
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Solution Overview
Problem
Current totem-pole power factor correction (PFC) circuits face challenges in implementing zero voltage switching (ZVS) control for switches S1 and S2, limiting efficiency improvements.
Innovation Solution
A power conversion circuit with a PFC circuit module and controller that performs PWM control based on load voltage, inductor current, and alternating current input voltage, using a voltage sampling unit, current sampling unit, alternating current signal processing unit, turn-off control unit, turn-on control unit, and PWM control unit to manage switching transistors S1 and S2, ensuring ZVS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional totem-pole PFC circuit is used, then the circuit structure is simple with few components, but ZVS control cannot be effectively implemented limiting efficiency
Solution Approach 1:
The patent implements ZVS control through feedback mechanisms that monitor the voltage at the midpoint between S1-S2 and use this information to timing the switching events. The controller adjusts switching moments based on real-time voltage conditions to ensure zero-voltage switching occurs, thereby minimizing energy loss while managing control complexity through intelligent feedback-based timing.
Solution Approach 2:
The patent applies preliminary action by proactively controlling the switching timing of S1 and S2 to occur at predetermined voltage conditions (when midpoint voltage reaches specific levels). The controller prepares and executes switching events at optimal moments based on predicted voltage waveforms, ensuring ZVS is achieved before energy losses can occur, thus improving efficiency without requiring overly complex real-time control.
2Loss of energy
If ZVS control is implemented on switches S1 and S2, then power conversion efficiency is improved, but control difficulty increases due to lack of effective ZVS solutions
Solution Approach 1:
The patent uses the midpoint voltage between switches S1 and S2 as an intermediary signal to determine optimal switching moments. By monitoring this intermediate voltage point rather than directly measuring complex switching conditions, the system can accurately detect when to execute ZVS for both S1 and S2. This intermediary measurement approach simplifies the detection process while ensuring precise switching timing for minimum energy loss.
3Measurement precision
If PWM control is performed based on multiple parameters (load voltage, inductor current, AC input voltage), then ZVS accuracy is enhanced, but control system complexity increases
Solution Approach 1:
The patent implements a multi-functional controller that simultaneously performs PWM control, ZVS timing, and multiple parameter monitoring (load voltage, inductor current, AC input voltage) through a single integrated control unit. This universal controller handles all switching decisions for S1 and S2 while coordinating multiple sensing functions, thereby achieving high switching moment precision without proportionally increasing overall system complexity through modular multi-function integration.
Data Source
AI summary
A power conversion circuit and a power conversion circuit control method. The power conversion circuit determines polarity of an alternating current voltage by using a PFC circuit controller, determines, based on a current of an inductor, a signal for controlling a secondary switch to be turned off, determines, based on a voltage at a midpoint of a series connection between a switching transistor S1 and a switching transistor S2, a signal for controlling the secondary switch to be turned on again and a signal for controlling a primary switch to be turned off, and performs PWM control on the switching transistor S1 and the switching transistor S2.