LED Driver Resonant Converter Frequency Control
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Solution Overview
Problem
Resonant converters used in LED lighting systems face inefficiencies when the load changes, as the frequency operating point shifts, leading to reduced efficiency and increased reactive current, and existing solutions like optocouplers for galvanic isolation are costly and have limited lifespan.
Innovation Solution
An LED converter with a control unit that adjusts the frequency and duty cycle of the half-bridge in a resonant converter to maintain the operating point within a predetermined frequency corridor, eliminating the need for galvanic isolation in feedback signals, and using a PFC circuit to regulate the DC voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If resonant converter frequency operating point is adjusted to match load changes, then efficiency is improved, but frequency stability deteriorates
Solution Approach 1:
The patent implements dynamic frequency adjustment by continuously monitoring the resonant converter's operating conditions and adapting the switching frequency to maintain optimal efficiency. The control system dynamically modifies the frequency operating point based on real-time load conditions, transforming a static frequency system into a dynamic one that adapts to changing requirements while maintaining stability through controlled adjustment.
Solution Approach 2:
The patent changes the frequency parameter of the resonant converter to optimize efficiency under varying load conditions. By adjusting the switching frequency within a controlled range, the system maintains the operating point within an optimal frequency corridor, thereby improving energy efficiency without causing uncontrolled frequency drift.
2Reliability
If optocoupler is used for galvanic isolation in feedback, then isolation reliability is improved, but cost and device complexity increase
Solution Approach 1:
The patent extracts and removes the optocoupler component from the feedback circuitry. By eliminating this isolation component, the system reduces complexity and cost while maintaining functional requirements through alternative approaches that do not require galvanic isolation in the feedback path.
Solution Approach 2:
The patent introduces an intermediary approach by using a measuring resistor and control unit that can operate without requiring galvanic isolation. The system uses an intermediate measurement method that allows feedback control to function effectively without the traditional optocoupler-mediated isolation barrier.
3Adaptability or versatility
If flyback converter is used for flexible LED supply, then adaptability to load changes is improved, but energy transmission capacity is limited
Solution Approach 1:
The patent creates a universal LED converter system that can handle various LED configurations and power requirements. By combining resonant converter topology with flexible control mechanisms, the system achieves multi-functionality that allows it to adapt to different load conditions while providing higher energy transmission capacity compared to traditional flyback converters.
Solution Approach 2:
The patent implements dynamic control mechanisms that allow the converter to adapt its operating parameters in real-time based on load conditions. This dynamic approach enables the system to maintain optimal performance across a wide range of power levels and LED configurations, achieving both flexibility and high power capability.
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 allows for flexible and efficient operation with varying loads while reducing costs and improving stability by maintaining high efficiency within a defined frequency range, eliminating the need for costly isolation methods.
Implementation Method 1
The resonant converter (LLC resonant converter) is, in particular, a form of DC-DC converter that uses an oscillating circuit to transmit energy. The resonant converter converts a DC voltage into a single-phase or multi-phase AC voltage
Data Source
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AI summary
The invention relates to an LED converter for operating a load comprising at least one LED series that includes at least one LED, preferably multiple LEDs. On the primary side, the LED converter comprises a resonant converter supplied with a direct current voltage. The resonant converter has a half-bridge that is constructed of two reciprocally clocked switches and that provides a supply voltage for the LED series through a serial/parallel resonance circuit connected to the midpoint of said half-bridge. To regulate the power transferred by the LED converter to the LED series as a feedback factor in each switch-on cycle, a control unit is designed to directly or indirectly determine a peak value of the feedback factor through the lower-potential switch of the half-bridge and to adjust the clocking of the half-bridge, i.e. the frequency and/or the duty factor, as a control factor.