LED Driver Module Capacitor Segmentation for AC Flicker
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Solution Overview
Problem
Existing driver modules for LEDs that operate directly from AC mains voltage experience flickering due to the alternating voltage not consistently reaching the forward voltage required for LED emission, leading to inefficient light output.
Innovation Solution
A driver module utilizing at least two capacitors that switch between parallel and series configurations in response to the AC mains voltage phases, ensuring a constant current supply to the LED string by charging and discharging the capacitors in synchronization with the AC waveform, thereby eliminating flickering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If LEDs are driven directly from AC mains voltage, then the device complexity is reduced, but flickering occurs due to insufficient voltage during parts of the AC cycle
Solution Approach 1:
The AC cycle is divided into multiple phases (charging phase, direct drive phase, discharging phase), and the capacitors are segmented into at least two separate components that can be independently controlled. This segmentation allows each capacitor to serve specific functions at specific times, resolving the contradiction by maintaining simple direct AC driving while eliminating flickering through phased capacitor operation.
Solution Approach 2:
The capacitor configuration dynamically switches between parallel connection during charging phase, series connection during discharging phase, and bypassed state during direct drive phase. This dynamic reconfiguration allows the circuit to adapt to different voltage conditions throughout the AC cycle, maintaining stable LED operation without complex switching circuitry.
2Reliability
If capacitors are used to maintain voltage during AC cycle, then light output stability is improved, but device complexity increases
Solution Approach 1:
The patent combines the voltage maintenance function with the existing AC driving circuit by using capacitors that are already present in the circuit. Instead of adding separate voltage regulation circuits, the capacitors are strategically positioned and configured to naturally maintain voltage during different phases, merging the stability function into the basic driving circuitry.
Solution Approach 2:
The capacitors automatically charge and discharge based on the AC voltage conditions without requiring external control. During the charging phase, capacitors naturally charge when voltage is sufficient; during the discharging phase, they automatically discharge to maintain voltage when AC voltage drops, providing self-regulating voltage maintenance without complex control circuits.
3Loss of energy
If capacitors charge and discharge in sync with AC waveform, then energy efficiency is improved, but control complexity increases
Solution Approach 1:
The capacitor charging and discharging operations are synchronized with the periodic AC waveform, with charging occurring during voltage peaks and discharging occurring during voltage troughs. This periodic action naturally follows the AC cycle rhythm, maximizing energy recovery and minimizing losses without requiring complex timing control, as the AC waveform itself provides the timing reference.
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 stable and efficient LED lighting by ensuring the LED string receives a constant current throughout the AC cycle, reducing flickering and improving light output consistency.
Implementation Method 1
a rectifier for generating a supply voltage by rectifying an input voltage
Implementation Method 2
a capacitive unit comprising at least two capacitors for storing electrical energy from the rectifier during a charging phase and for providing electrical energy to the load path during a discharging phase
Implementation Method 3
For an LED string to emit light and for a current to flow through the LED string, it is indeed necessary that the voltage across the LEDs is high enough. The voltage should be higher than the forward voltage of the LED string.
Data Source
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AI summary
The invention proposes a driver module for driving LEDs, wherein the driver module comprises: - a rectifier (D1) for generating a supply voltage by rectifying an input AC voltage (Vin), - a load path with nodes (B, C) for connecting an LED string (10) comprising one or a plurality of LEDs (D), - a current source (IS1) coupled with the load path for generating a preferably constant current for the load path, and - a capacitive unit comprising at least two capacitors (C1, C2) for storing electrical energy from the rectifier (D1) during a charging phase and for providing electrical energy to the load path during a discharging phase, wherein the capacitive arrangement (11, 11', 11'') is configured such that the two capacitors (C1, C2 ) are in a parallel arrangement (11) in the charging phase and in a serial arrangement (11'') in the discharging phase.