Pulsed Current Averaging Controller for LED Arrays
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Solution Overview
Problem
Existing off-line LED drivers are inefficient, unstable, and electromagnetically incompatible, often requiring complex feedback loops and multiple components, which complicates their design and increases size and cost, while failing to provide reliable protection for LEDs and driver components, especially for high brightness applications.
Innovation Solution
A high-efficiency, stable, and electromagnetically compatible LED driver controller using pulsed current averaging methodology with a minimal component count, implemented in off-line non-isolated and isolated drivers, which regulates current through a switch and inductor, adjusting the on-time and off-time of the switching power converter to maintain a constant average current level and provide reliable protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex feedback loops and multiple components are used in off-line LED drivers, then current regulation capability is improved, but device complexity and size increase
Solution Approach 1:
The patent extracts and eliminates the complex secondary-side feedback loop across the transformer, replacing it with a primary-side current sensing mechanism. This extraction removes the problematic feedback path that required multiple components while maintaining current regulation capability through direct primary current measurement and control.
Solution Approach 2:
The controller integrates multiple functions into a single device: current sensing, pulse width modulation, frequency regulation, and protection mechanisms all occur within the primary-side controller. This multi-functionality eliminates the need for separate feedback circuits, transformers with secondary sensing, and additional regulation components.
2Measurement precision
If current mode regulator with ramp compensation is used, then current control precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the current sensing function and control function into a single primary-side controller. The current sensor directly feeds into the controller which integrates the regulation logic, eliminating the need for separate ramp compensation circuits and multiple functional blocks required by traditional current mode regulators.
3Stability of the object's composition
If constant off time boost converter or hysteric pulse train booster is used, then stability is improved, but electromagnetic interference increases
Solution Approach 1:
The patent implements dynamic frequency regulation where the switching frequency is not fixed but adapts based on the instantaneous voltage and current conditions. This dynamic operation allows the converter to maintain stability while avoiding the fixed-frequency EMI issues of hysteric boosters and constant off-time converters, as the frequency modulation spreads and reduces peak EMI emissions.
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 achieves high efficiency, stability, and electromagnetic compatibility, reducing the size and cost of LED drivers while ensuring reliable protection for LEDs and driver components, enabling efficient power delivery to high brightness LED arrays.
Implementation Method 1
providing current to the inductor for a first predetermined period of time; following the first predetermined period of time, providing current to the electrical load
Data Source
AI summary
Exemplary embodiments provide a system, method and apparatus for regulating current in loads, such as in an array of independent pluralities of light emitting diodes (“LEDs”). An exemplary system comprises a multiplexer adapted to switch current to each independent string of LEDs; a first controller to maintain a substantially constant average current level to the plurality of LEDs; and a second controller to modulate a current amplitude and duration of time division multiplexing for each independent string of LEDs. Another aspect of the system provides for modulating the on time for switching current to maintain a substantially constant average current level and to respond and converge quickly to changing current reference levels.