Soft-Switching PFC Circuit for Lower Turn-On and Switching Loss
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Solution Overview
Problem
Current power factor correction (PFC) circuits in electronic systems suffer from high turn-on and switching losses due to hard switching methods, leading to poor performance.
Innovation Solution
A PFC circuit employing soft switching on switching transistors, utilizing a control module to manage a single-phase correction circuit with inductors and bridge arms, reducing turn-on and switching losses by controlling switching transistors based on current and voltage conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If hard switching method is used for switching transistor, then circuit structure is simple, but turn-on loss and switching loss are large
Solution Approach 1:
The patent introduces a resonant circuit comprising an inductor and a capacitor as an intermediary between the power circuit and switching transistor. This resonant circuit generates resonance current that enables soft switching of the transistor, reducing turn-on and switching losses without significantly complicating the overall circuit structure.
Solution Approach 2:
The patent changes the switching parameters by implementing soft switching through resonance. The switching transistor operates in a soft switching mode where the voltage and current waveforms are shaped by the resonant circuit, changing the physical state parameters during switching transitions to minimize energy losses.
2Loss of energy
If soft switching method is used for switching transistor, then turn-on loss and switching loss are reduced, but circuit structure becomes complex
Solution Approach 1:
The resonant circuit acts as an intermediary that adds minimal complexity while enabling soft switching. The inductor and capacitor are strategically placed to create resonance without requiring complete redesign of the power factor correction circuit architecture.
Solution Approach 2:
The resonant circuit serves multiple functions: it generates resonance current for soft switching, shapes voltage and current waveforms, and maintains power factor correction capability. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in circuit complexity.
3Ease of manufacture
If diode rectification is used in PFC circuit, then rectification is simple, but power factor correction performance is poor
Solution Approach 1:
The patent replaces the passive diode rectification mechanism with an active switching circuit controlled by PWM signals. This substitution enables dynamic control of the rectification process, allowing the circuit to actively shape the input current waveform to match the voltage waveform, thereby achieving superior power factor correction performance.
Solution Approach 2:
The patent introduces dynamic control through PWM-switched transistors that actively regulate the rectification process. The switching timing and duration are dynamically adjusted based on the input voltage and current conditions, enabling the circuit to maintain optimal power factor correction across varying operating conditions.
Data Source
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AI summary
Embodiments of this application provide a power factor correction PFC circuit, a control method, an electric vehicle, and a charging pile. The PFC circuit includes a control module and at least one single-phase correction circuit, and the single-phase correction circuit includes a first inductor, a second inductor, a first bridge arm, a second bridge arm, and a third bridge arm. The control module is configured to control each switching transistor in the first bridge arm, the second bridge arm, and the third bridge arm in the single-phase correction circuit to be turned on or off. The single-phase correction circuit is configured to perform power factor correction on a single-phase alternating current provided by an alternating current circuit and convert the single-phase alternating current into a direct current output to a direct current circuit, or perform power factor correction on a direct current provided by a direct current circuit and convert the direct current into a single-phase alternating current output to an alternating current circuit. According to embodiments of this application, soft switching of the switching transistor is implemented, a turn-on loss and a switching loss of the PFC circuit can be reduced, and performance of the PFC circuit can be improved.