Resonant Converter Integrating Power Factor Correction
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Solution Overview
Problem
Resonant converters with power factor correction typically require a dedicated PFC circuit, which increases cost and reduces power density and efficiency.
Innovation Solution
A resonant converter design that integrates a rectifier bridge, capacitors, diodes, transistors, and a resonant tank with an intrinsic power factor correction function, eliminating the need for a dedicated PFC circuit by using a controller with an error amplifier and voltage controlled oscillator to generate control signals for the transistors, thereby achieving high power factor and low Total Harmonic Distortion (THD).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a dedicated PFC circuit is used as the first stage, then high power factor is achieved, but cost increases and power density and efficiency are reduced
Solution Approach 1:
The patent combines the PFC function with the resonant converter circuit by integrating a first transistor and first capacitor that operate during specific phases of the resonant cycle to provide power factor correction. This merging eliminates the need for a separate dedicated PFC circuit, reducing component count and overall system complexity while maintaining high power factor performance.
Solution Approach 2:
The resonant converter circuit is designed to perform multiple functions simultaneously: power conversion, power factor correction, and resonance-based efficient switching. The first transistor and first capacitor serve dual purposes by enabling both PFC during their conduction phase and participating in the overall power conversion process, making the circuit multi-functional and eliminating redundant components.
2Ease of manufacture
If a dedicated PFC circuit is used as the first stage, then high power factor is achieved, but power density is reduced
Solution Approach 1:
The PFC function is merged into the resonant converter circuit structure, sharing physical space and magnetic components with the power conversion function. The first transistor and first capacitor are integrated into the existing circuit topology, eliminating the need for separate PFC circuitry and associated magnetic components, thereby increasing power density while maintaining high power factor.
3Ease of manufacture
If a dedicated PFC circuit is used as the first stage, then high power factor is achieved, but efficiency is reduced
Solution Approach 1:
The PFC operation is merged with the resonant converter's natural switching cycles, utilizing the resonant tank's energy oscillation to minimize additional switching losses. The first transistor and first capacitor operate in coordination with the resonant frequency, reducing hard switching losses and improving overall efficiency while achieving high power factor correction.
Solution Approach 2:
The power factor correction is achieved through periodic action during specific phases of the resonant cycle. The first transistor conducts during intervals when the resonant tank voltage is at specific levels, utilizing the natural periodic oscillation of the resonant circuit to provide PFC without continuous energy loss, thereby improving efficiency while maintaining high power factor.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves high power factor and low THD without a dedicated PFC circuit, enhancing efficiency and reducing costs by utilizing the intrinsic power factor correction capabilities of the resonant converter circuit structure.
Implementation Method 1
When resonance occurs, current or voltage of the resonant tank periodically crosses zero. This allows transistors in the resonant converter to turn on or turn off at zero voltage or zero current condition
Implementation Method 2
an error amplifier having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is configured to receive a reference signal, the second input terminal is configured to receive a feedback signal indicating the output signal of the resonant converter, and wherein based on the reference signal and the feedback signal, the error amplifier generates a compensation signal at the output terminal
Implementation Method 3
a voltage controlled oscillator having an input terminal and an output terminal, wherein the input terminal is coupled to the output terminal of the error amplifier, and wherein based on the compensation signal, the voltage controlled oscillator generates a control signal at its output terminal to control the first and second transistors
Data Source
AI summary
A resonant converter includes: a rectifier bridge; a first capacitor coupled across output terminals of the rectifier bridge; a diode with its anode coupled to a first terminal of the first capacitor; a second capacitor with a first terminal coupled to the cathode of the diode, and a second terminal coupled to a second terminal of the first capacitor; a first transistor having a first terminal coupled to the first terminal of the second capacitor; a second transistor having a first terminal coupled to a second terminal of the first transistor, and a second terminal coupled to the second terminal of the first capacitor; a resonant tank having a first input terminal coupled to the first terminal of the first capacitor, and a second input terminal coupled to the second terminal of the first transistor and the first terminal of the second transistor; and a rectifying and filtering circuit coupled across output terminals of the resonant tank, and configured to provide an output signal to a load.