Resonant Converter With Switchable Primary Winding Taps
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Solution Overview
Problem
Resonant converters face efficiency degradation over a large input voltage range and struggle with overpower situations, particularly in low power applications below 75 watts, where they operate away from the optimal load-independent point, leading to increased switching frequencies and RMS losses.
Innovation Solution
The implementation of an LLC resonant converter with an asymmetrical operation mode and adaptable turns ratio, utilizing primary winding taps and clamping diodes to maintain efficiency across varying input and output voltages, and employing asymmetrical control to manage switching frequencies and RMS currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If resonant converter operates over large input voltage range, then adaptability is improved, but efficiency deteriorates
Solution Approach 1:
The patent implements dynamic adaptation by providing multiple primary winding taps on the transformer that can be selectively connected based on the input voltage level. This allows the converter to dynamically adjust its turns ratio to maintain optimal operating conditions across a wide input voltage range (90-264 VAC), preventing efficiency degradation that would occur with a fixed turns ratio design.
Solution Approach 2:
The patent changes the electrical parameter (turns ratio) by selecting different primary winding taps corresponding to different input voltage ranges. This parameter adjustment allows the converter to maintain the reflected output voltage within the optimal range for resonant operation, thereby preserving efficiency across universal mains voltages.
2Power
If resonant converter handles overpower situations, then power capacity is improved, but operation point stability deteriorates
Solution Approach 1:
The patent enables the converter to handle overpower situations (up to 200% of nominal power) by dynamically selecting appropriate primary winding taps based on the power demand and input voltage conditions. This dynamic adjustment maintains the operating point stability even under varying load conditions by adapting the turns ratio to keep the reflected output voltage within the optimal range for resonant operation.
3Device complexity
If converter uses fixed turns ratio, then device complexity is reduced, but efficiency over voltage range deteriorates
Solution Approach 1:
Instead of using a single fixed turns ratio, the patent employs multiple primary winding taps that can be selectively activated. This dynamic configuration allows the transformer to adapt its effective turns ratio based on input voltage conditions, maintaining high efficiency across universal mains operation without requiring complex additional circuitry.
Solution Approach 2:
The primary winding is segmented into multiple taps, each optimized for specific input voltage ranges. This segmentation allows selective use of appropriate winding sections to maintain optimal reflected output voltage levels, thereby preserving efficiency without requiring multiple separate transformers or complex switching arrangements.
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 maintains high efficiency by optimizing the resonant converter's operation close to the resonance frequency, reducing switching frequency increases and RMS losses, and effectively handling overpower situations without significant transformer size increases, thus achieving high power density and efficiency across universal mains operation.
Implementation Method 1
resonant converter utilizing an LLC resonant circuit
Implementation Method 2
transformer having a primary side connected in series with said series inductor and, the primary side being configurable to use at least one primary winding tap and a secondary side for connecting to a rectifying circuit
Implementation Method 3
secondary side for connecting to a rectifying circuit for providing a rectified DC voltage
Data Source
AI summary
Disclosed is a power converter including a generator configured to generate a sequence of output voltage waveforms, a resonant tank connected to the generator comprising at least one capacitor and at least one inductor, a transformer including a primary side connected in series with said series inductor and, the primary side being configurable to use at least one primary winding tap and a secondary side for connecting to a rectifying circuit for providing a rectified DC voltage to an output load circuit, a first switch and a second switch on the primary side connected to the primary winding, wherein the at least one primary winding is selected by the first switch or the second switch to select a different reflected output voltage by closing the first switch or the second switch.