Resonant Clamped Power Conversion Circuit for Wide-Input Soft Switching
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Solution Overview
Problem
Conventional power conversion circuits with wide input voltage ranges face inefficiencies due to high on-resistance and conduction losses, particularly in flyback and active clamp forward topologies, which hinder soft switching and result in low energy efficiency and increased heat dissipation.
Innovation Solution
A power conversion circuit design that incorporates a clamping branch circuit, resonant inductor, and resonant capacitor, allowing for soft switching of all switches and reducing on-resistance by using lower withstand voltage switches, thereby maintaining high energy efficiency across a wide input voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If high withstand voltage switches are used in conventional flyback topology, then the voltage requirement is met, but the on-resistance becomes too high causing large conduction loss
Solution Approach 1:
The patent changes the voltage stress parameters of switches through the introduction of resonant elements and clamping circuits. By creating resonant valleys and clamping voltage peaks, the effective voltage across switches is reduced, allowing use of lower voltage-rated switches with lower on-resistance, thus reducing conduction losses while still meeting the system voltage requirements.
Solution Approach 2:
The patent introduces resonant capacitors and clamping capacitors as intermediary elements between the main voltage sources and switches. These intermediary capacitors absorb voltage peaks and create resonant conditions that protect switches from full voltage stress, enabling the use of switches with lower withstand voltage ratings and consequently lower on-resistance.
2Power
If conventional flyback topology operates in continuous conduction mode, then output power increases, but secondary switch experiences reverse recovery loss
Solution Approach 1:
The patent introduces periodic resonant action through resonant inductors and capacitors. The resonant oscillations create periodic current valleys that allow the secondary switch to turn off at zero current or near-zero current, eliminating reverse recovery losses. This periodic resonant behavior is superimposed on the continuous conduction mode operation to achieve soft switching.
Solution Approach 2:
The patent utilizes electrical resonance (analogous to mechanical vibration) through properly tuned LC circuits. The resonant oscillations create vibrating current waveforms that naturally pass through zero-crossing points, enabling the secondary switch to turn off at zero current and avoiding the reverse recovery effect that plagues conventional CCM operation.
3Loss of energy
If resonant elements are added to primary circuit, then soft switching is improved, but complete soft switching cannot be realized
Solution Approach 1:
The patent segments the soft switching solution into two independent parts: primary side resonant circuit for primary switch soft switching, and secondary side resonant-clamping circuit for secondary switch soft switching. Each side has its own resonant elements and control mechanism, allowing both switches to achieve complete soft switching independently and reliably.
Solution Approach 2:
The patent prepares the voltage and current conditions in advance through resonant charging and discharging of capacitors before the switching events. The clamping capacitor is pre-charged to the required voltage, and resonant inductors are pre-positioned to provide the necessary current waveforms, ensuring that when switches turn on or off, the conditions for complete soft switching are already in place.
4Adaptability or versatility
If conventional active clamp forward topology is used, then wide input voltage range is supported, but primary switch cannot realize complete soft switching
Solution Approach 1:
The patent introduces dynamic resonant elements that adapt to different input voltage conditions. The resonant frequency and impedance are designed to vary with input voltage, maintaining optimal soft switching conditions across the entire wide input voltage range. This dynamic adaptation allows the primary switch to achieve complete soft switching regardless of the input voltage level.
Solution Approach 2:
The patent designs the resonant-clamping circuit to perform multiple functions simultaneously: it provides soft switching for the primary switch, clamps voltage to protect the switch, and adapts to wide input voltage variations. This multi-functional design enables complete soft switching across the entire operating range, making the circuit universally applicable to different voltage conditions.
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 circuit achieves reduced losses and high energy efficiency by enabling soft switching and using lower withstand voltage switches, while maintaining efficiency under varying input conditions.
Implementation Method 1
The resonant inductor and the resonant capacitor are configured to resonate in the power conversion circuit
Data Source
AI summary
The present disclosure provides a power conversion circuit including positive and negative input terminals, a clamping branch circuit, a first primary switch, a transformer, a rectifier circuit, a resonant inductor, a resonant capacitor, and positive and negative output terminals. The clamping branch circuit includes a clamping capacitor and a second primary switch serially connected between the first and second terminals thereof. The first terminal is coupled to the positive input terminal. The first primary switch is connected between the second terminal and the negative input terminal. The primary winding of the transformer is connected to the clamping branch circuit in parallel. The rectifier circuit includes first and second bridge arms connected in parallel. Connection terminals in the first and second bridge arms are coupled to two terminals of the secondary winding of the transformer correspondingly. The first and second bridge arms are coupled between the positive and negative output terminals.