Multi-Phase Isolated Resonant Converter for Wide Voltage Range
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Solution Overview
Problem
Resonant converters face limitations in achieving a wide input/output voltage range due to the need for a wide switching frequency range, which increases driving and switching losses, and results in reduced power delivery capability and increased temperature issues due to high RMS current stress.
Innovation Solution
A multi-phase isolated resonant converter is controlled using a combination of switching frequency, duty ratio, and delay-time control to reduce the switching frequency range, allowing for wider voltage conversion ratios and active current-sharing across phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wide switching frequency range is used to achieve wide input/output voltage range, then voltage conversion capability is improved, but driving and switching losses increase
Solution Approach 1:
The patent divides the voltage conversion task across multiple phases (e.g., three-phase converter), where each phase operates at a reduced switching frequency. This segmentation allows the system to achieve wide voltage conversion range through phase interleaving and duty ratio control while each individual phase operates efficiently at lower frequencies, reducing overall driving and switching losses.
Solution Approach 2:
The patent employs dynamic duty ratio control for secondary side switches to achieve wide voltage conversion range without requiring wide switching frequency range. By dynamically adjusting the duty ratio of secondary side switches based on input/output voltage conditions, the system maintains efficient operation across varying voltage conditions while operating at a fixed or narrowly ranged switching frequency.
2Power
If high RMS current stress is present to deliver power, then power delivery capability is improved, but temperature issues increase
Solution Approach 1:
The patent segments the power delivery across multiple phases, distributing the total power handling task among several parallel converter phases. This segmentation reduces the RMS current stress on individual components and switches in each phase, thereby reducing conduction losses and thermal stress while maintaining high overall power delivery capability through the combined output of all phases.
Solution Approach 2:
The patent implements phase interleaving where multiple phases operate with phase-shifted switching patterns, ensuring continuous power delivery to the output. This continuous action smooths the output current and reduces peak current stresses, allowing sustained high power delivery with reduced thermal stress on individual components due to the distributed and continuous nature of power transfer.
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
This approach enables efficient operation with a reduced switching frequency range, enhancing power delivery capability and reducing thermal stress by balancing currents and optimizing voltage conversion across a wide input/output voltage range.
Implementation Method 1
a resonant converter uses a resonant-tank circuit to shape voltage or current waveforms, or both, to minimize switching losses and to allow high frequency operations without compromising conversion efficiency
Implementation Method 2
the resonant-tank circuit includes resonant inductor LP and capacitors CP and CS... connected in series through a transformer TR
Data Source
AI summary
The present disclosure provides a single- and multi-phase DC/DC converter and a control method thereof that can offer a wide range of voltage conversion ratio by substantially reducing the switching frequency range, thereby resulting in performance improvement. Reduction in the switching frequency range is achieved by controlling the output voltage or current with a combination of variable duty ratio, variable frequency, and delay-time control.