Multi-channel LED Driver with PWM Voltage Regulation
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Solution Overview
Problem
Existing power supplies for large LED arrays require multiple constant current sources, leading to complexity, cost, and reduced efficiency due to the need for variable voltage and current control, especially when emulating incandescent lamp capabilities for varying light flux.
Innovation Solution
A multi-channel constant current source with a power source stage using pulse width modulation and a switching circuit, coupled with transformers and constant current drivers, allows for efficient variable voltage and current control across multiple LED strings, reducing the need for multiple power supplies and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple separate constant current power supplies are used for each LED string, then current regulation precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple constant current power supply channels into a single integrated power supply device. The controller coordinates multiple LED string currents through a unified control architecture, eliminating the need for separate independent power supplies for each string while maintaining precise current regulation through centralized monitoring and adjustment.
Solution Approach 2:
The single power supply device is designed to universally drive multiple LED strings simultaneously. The controller can independently regulate current for each LED string connected to the device, making it a multi-functional unit that replaces multiple specialized power supplies while maintaining the precision required for each individual string.
2Adaptability or versatility
If variable voltage and current control is implemented for wide-range light flux adjustment, then adaptability is improved, but efficiency deteriorates due to additional conversion stages
Solution Approach 1:
The patent implements dynamic control of LED string currents through a controller that can adjust current levels in real-time based on desired light flux requirements. The system dynamically switches between different LED strings and adjusts their individual currents to achieve wide-range illumination control while minimizing energy conversion stages.
Solution Approach 2:
The system changes operational parameters by selectively activating different LED strings and adjusting their current levels rather than using multiple conversion stages. The controller modifies current parameters directly for each string, enabling wide-range light flux adjustment while maintaining high efficiency by avoiding unnecessary voltage-to-current conversion stages.
3Device complexity
If LED strings are connected in series to reduce power supply count, then device complexity is reduced, but voltage requirements increase significantly
Solution Approach 1:
The patent segments the LED array into multiple parallel strings that can be independently controlled. Instead of connecting all LEDs in a single long series string, the system divides them into manageable segments (strings) connected in parallel, each driven by the same power supply but independently controllable, thereby reducing the voltage requirement compared to a single long series string.
Solution Approach 2:
The controller acts as an intermediary that coordinates current distribution among multiple LED strings. It manages the parallel configuration by independently regulating each string's current, enabling the system to handle high total current requirements through distributed control rather than requiring excessively high voltages that would be needed for a single series string.
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 solution enables high-efficiency, variable-voltage power supply for LED arrays of varying sizes, reducing complexity and cost while maintaining efficient LED string current regulation, even with mismatched LED strings, and allowing for wide-range current and voltage control.
Implementation Method 1
A multi-channel constant current source with a power source stage using pulse width modulation and a switching circuit
Implementation Method 2
coupled with transformers and constant current drivers
Implementation Method 3
driving strings of light-emitting diodes (LEDs)
Data Source
AI summary
A multi-channel constant current source particularly suitable for driving an array of light-emitting diodes as an illumination apparatus provides a power source stage voltage regulator for providing a variable voltage using pulse width modulation as an input to a plurality of constant current driver channels to regulate the constant current provided. Pulse width modulation thus allows both the power source stage and the constant current driver operating frequencies to be decoupled and individually optimized to maintain efficiency while emulating dimming effects of, for example, incandescent bulbs, over a full range of light output flux. Pulse width modulation can also be employed in the constant current channel drivers to avoid chromaticity shift during dimming.