Resonant Capacitor Switching Control for Wide-Range LLC Conversion
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Solution Overview
Problem
Resonant power conversion circuits face inefficiencies at low output voltages and light loads due to high switching frequencies, necessitating optimization for wider output voltage ranges and improved efficiency.
Innovation Solution
A power conversion circuit and control method that adjusts the threshold voltage and detects current and voltage across a resonant capacitor to optimize switching, achieving zero-voltage switching and reducing ripple, thereby enhancing efficiency and allowing smaller output capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a resonant power conversion circuit operates at high switching frequency to meet low output voltage or light load conditions, then the output voltage range can be extended, but the conversion efficiency deteriorates
Solution Approach 1:
The patent implements dynamic control of the resonant power conversion circuit by detecting the voltage at the switch node and dynamically adjusting the switching timing of transistors. The control circuit monitors the switch node voltage and triggers transistor switching at optimal moments, enabling the circuit to adapt its operating characteristics in real-time based on load and voltage conditions, thereby maintaining efficiency across a wide output voltage range
Solution Approach 2:
The patent employs feedback control mechanisms where the control circuit continuously monitors the switch node voltage and uses this information to regulate transistor switching. The feedback signal from the switch node voltage detection is used to adjust the switching timing, ensuring the circuit operates at optimal efficiency points while maintaining the desired output voltage across varying load conditions
2Adaptability or versatility
If the switching frequency is increased to achieve low output voltage, then the output voltage range is extended, but the switching power loss increases
Solution Approach 1:
The patent applies preliminary action by detecting the switch node voltage in advance and using this information to predict the optimal switching moment. The control circuit prepares the switching action by monitoring voltage trends and triggers transistor switching at the precise moment when switching losses are minimized, rather than using fixed-frequency switching
Solution Approach 2:
The patent changes the switching parameter from fixed frequency to variable timing based on switch node voltage detection. By adjusting the switching timing parameter dynamically according to the detected voltage conditions, the circuit optimizes the switching instant to minimize power loss while maintaining the ability to deliver low output voltages
3Stability of the object's composition
If the output voltage ripple is reduced, then the output voltage stability is improved, but the output capacitor size must be increased
Solution Approach 1:
The patent implements self-service by using the resonant capacitor's inherent voltage characteristics to naturally balance the currents in rectification units. The resonant capacitor's voltage waveform, detected and controlled by the control circuit, automatically regulates the current distribution, reducing output voltage ripple without requiring additional large output capacitors for ripple filtering
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 solution provides a wider output voltage range with reduced switching power loss, lower ripple, and the ability to use smaller output capacitors, improving efficiency and cost-effectiveness.
Implementation Method 1
LLC resonant power conversion circuit
Implementation Method 2
resonant capacitor is coupled between the resonant node and a ground
Implementation Method 3
The transformer comprises a primary coil and a secondary coil
Data Source
AI summary
A power converter includes a transformer, a resonant capacitor, a high-side transistor, a low-side transistor, a rectification circuit, a feedback circuit, a detection circuit, and a control circuit. The transformer includes a primary coil coupled to a switch node and a secondary coil. The resonant capacitor is coupled to the primary coil. The high-side transistor provides an input voltage to the switch node, and the low-side transistor couples the switch node to the ground. The rectification circuit converts the energy of the secondary coil into an output voltage. The feedback circuit compares the output voltage with a reference voltage to generate a compensation signal. The detection circuit generates a current detection signal and a voltage detection signal. The control circuit drives the high-side transistor and the low-side transistor based on the current detection signal, the voltage detection signal, the compensation signal, and the input signal.