Resonant Converter Phase-Shift Control for Light-Load Gain Stability
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Solution Overview
Problem
Existing power converters face challenges in maintaining gain control under light load conditions due to parasitic capacitances of secondary side switches participating in resonance, leading to nonlinearity and reduced efficiency.
Innovation Solution
Implementing a phase shift mode in the power converter operation to reduce gain by offsetting the on-times and off-times of primary switches, thereby minimizing the involvement of parasitic capacitances in resonance, without altering the duty cycle or switching frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power converter operation is used under light load conditions, then the converter operates at fixed duty cycle and switching frequency, but parasitic capacitances of secondary side switches participate in resonance causing gain control loss and nonlinearity
Solution Approach 1:
The patent applies dynamics by transitioning from fixed duty cycle operation to variable duty cycle operation on the secondary side. The controller dynamically adjusts the duty cycle of secondary switches based on load conditions, enabling the converter to maintain gain control under light load by preventing parasitic capacitance resonance through active duty cycle modulation rather than fixed operation
Solution Approach 2:
The patent changes the operating parameters by introducing variable duty cycle control for secondary switches. By modifying the duty cycle parameter dynamically based on detected load conditions, the system alters the resonance characteristics and prevents parasitic capacitance from dominating the gain control, thereby maintaining stable operation across different load conditions
2Loss of energy
If phase shift mode is implemented to reduce gain variations, then efficiency is enhanced under light load, but the control complexity increases due to overlapping and non-overlapping phase management
Solution Approach 1:
The patent segments the switching cycle into distinct overlapping and non-overlapping phases. By dividing the control waveform into these segments with specific duty cycles, the system achieves gain control and efficiency improvement while managing complexity through structured temporal segmentation rather than continuous complex modulation
Solution Approach 2:
The patent implements periodic action through repetitive overlapping and non-overlapping phase patterns. The controller applies periodic duty cycle variations to secondary switches, creating a rhythmic control scheme that maintains gain control over multiple switching cycles while reducing efficiency losses associated with parasitic resonance
3Object-generated harmful factors
If secondary switches are closed during non-overlapping phase, then parasitic capacitance involvement in resonance is minimized, but switch timing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring the secondary switch duty cycles before the actual switching occurs. The controller预先 sets the duty cycle parameters for overlapping and non-overlapping phases, ensuring that switches are closed at precise moments during the non-overlapping phase to prevent parasitic resonance, thereby reducing the burden on real-time timing precision
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 phase shift mode effectively reduces gain variations and enhances efficiency by stabilizing the converter's operation under light load conditions, improving control predictability and reducing nonlinearity caused by secondary side parasitic capacitances.
Implementation Method 1
a primary side including a primary full bridge coupled to a primary winding... a secondary side including a secondary full bridge coupled to a secondary winding
Implementation Method 2
resonant converter includes a primary side including a primary full bridge coupled to a primary winding... Examples of power converters include inductor-inductor-capacitor (LLC) converters and capacitor-inductor-inductor-inductor-capacitor (CLLLC) converters
Data Source
AI summary
In described examples, a resonant converter includes a primary side, a secondary side, and a controller. The primary side includes a primary full bridge coupled to a primary winding. The primary full bridge includes first and second high-side primary switches and first and second low-side primary switches. The secondary side includes a secondary full bridge coupled to a secondary winding. The secondary full bridge includes two high-side secondary switches and two low-side secondary switches. The controller operates the resonant converter in a phase shift mode with an overlapping phase and a non-overlapping phase. In the overlapping phase the first high-side primary switch and the first low-side primary switch are closed. In the non-overlapping phase either the first high-side primary switch or the first low-side primary switch is closed and the other is open. The controller closes either the two high-side or the two low-side secondary switches during the non-overlapping phase.