Pulse Modulation for Isolated LED Dimming and Voltage Control
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Solution Overview
Problem
Existing LED drivers lack effective isolation and control mechanisms to safely and efficiently manage power and dimming signals across transformer windings, leading to potential safety risks and inefficiencies in LED lighting systems.
Innovation Solution
A driver system utilizing a transformer with an auxiliary winding for parallel voltage supply, coupled with a galvanic isolation barrier and opto-isolator, to transmit pulse modulation signals containing brightness and voltage information across the isolation barrier, enabling safe and efficient control of LED power and dimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a transformer with auxiliary winding is used for parallel voltage supply, then power efficiency and electrical isolation are improved, but device complexity increases
Solution Approach 1:
The transformer is designed with multiple windings (primary winding, secondary winding, and auxiliary winding) that serve different functions: the primary winding handles main power transfer, the secondary winding provides isolated power output, and the auxiliary winding supplies power to the dimming circuit. This multi-functionality allows a single transformer component to perform multiple roles, improving overall system power efficiency while managing complexity through integrated design
Solution Approach 2:
The transformer is segmented into multiple independent windings (primary, secondary, auxiliary) that can be independently controlled and regulated. This segmentation allows the auxiliary winding to independently power the dimming circuit while the main transformer handles LED power, enabling efficient power distribution and electrical isolation without requiring separate power supply circuits
2Reliability
If galvanic isolation barrier and opto-isolator are used for signal transmission, then safety and electrical isolation are improved, but device complexity increases
Solution Approach 1:
An opto-isolator is introduced as an intermediary component between the primary-side control circuit and the secondary-side LED load. This intermediary transmits control signals across the galvanic isolation barrier using optical coupling, enabling communication while maintaining electrical isolation and safety. The opto-isolator acts as a mediator that prevents direct electrical connection while allowing signal transmission
Solution Approach 2:
The patent replaces direct electrical signal transmission with optical signal transmission through the opto-isolator. Instead of using electrical wires to transmit control signals across the isolation barrier, the system uses light (optical energy) to carry information, thereby eliminating conductive paths and enhancing safety while maintaining signal transmission capability
3Measurement precision
If auxiliary winding is used for isolated auxiliary voltage, then control precision for dimming is improved, but device complexity increases
Solution Approach 1:
The auxiliary winding provides an isolated power supply to the dimming circuit, enabling precise control of LED brightness through feedback mechanisms. The controller can regulate the auxiliary winding output voltage to maintain stable operation of the dimming circuitry, allowing accurate dimming control without direct electrical connection to the LED load. This feedback capability ensures precise dimming while maintaining electrical isolation
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 electrical isolation, enhances safety by preventing ground loops, and optimizes power efficiency by maintaining a steady output voltage, ensuring reliable and efficient LED lighting operations.
Implementation Method 1
The transformer may provide electrical isolation between the primary and secondary-sides of the transformer
Implementation Method 2
a signal is transmitted to a controller over a galvanic isolation barrier
Data Source
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AI summary
In an example, a controller that controls one or more light-emitting diodes (LEDs), wherein the controller is configured to receive an output voltage from a secondary transformer winding of a transformer, and receive first information across a galvanic isolation barrier, wherein the first information includes a desired LED brightness. The controller is further configured to receive second information across the galvanic isolation barrier, and the second information includes an output voltage of an auxiliary transformer winding; The controller may control the one or more LEDs based on the first information, and also control the output voltage of a secondary transformer winding and the output voltage of the auxiliary transformer winding based on the first information and the second information.