LED Control System Unity Power Factor via Fixed Frequency PWM
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Solution Overview
Problem
Existing LED control systems for automotive and AC lighting applications are costly and lack efficient power factor control, making them undesirable for low-cost, high-efficiency solutions.
Innovation Solution
A PWM-based LED control system that operates LEDs with a substantially unity power factor by using a switching power supply controller with a fixed frequency and duty cycle, eliminating the need for complex multiplier circuits and voltage sensing, and incorporating a bridge rectifier, error amplifier, and power converter to maintain a constant DC voltage across LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional LED control systems are used, then power factor control is achieved, but system cost increases
Solution Approach 1:
The patent extracts and eliminates complex multiplier circuits and voltage sensing components from the LED control system. By using a simplified approach with a bridge rectifier, error amplifier, and power converter operating at fixed frequency and duty cycle, the system achieves unity power factor without requiring expensive complex sensing or multiplier circuits, thus reducing system cost while maintaining power factor control
Solution Approach 2:
The patent employs cost-effective standard electronic components (bridge rectifier, error amplifier, power converter) instead of expensive specialized circuits. These readily available components enable the system to achieve power factor control at minimal cost, making the solution economically viable for widespread adoption
2Loss of energy
If complex multiplier circuits and voltage sensing are used, then power factor control is improved, but device complexity increases
Solution Approach 1:
The patent removes complex multiplier circuits and voltage sensing components from the system architecture. The solution uses a bridge rectifier, error amplifier, and power converter configured with fixed frequency and duty cycle, eliminating the need for complex sensing or multiplier circuits while maintaining unity power factor control
Solution Approach 2:
Instead of using complex circuits to control power factor, the patent inverts the approach by using a simple fixed-frequency and fixed-duty-cycle configuration that naturally achieves unity power factor. This reverse thinking simplifies the circuit architecture while maintaining the desired power factor control performance
3Device complexity
If simple LED control systems are used, then cost is reduced, but power factor control capability is lost
Solution Approach 1:
The patent designs a simple system using universal standard components (bridge rectifier, error amplifier, power converter) that simultaneously achieves multiple functions: power factor control, constant DC voltage generation, and cost reduction. The fixed frequency and duty cycle configuration enables unity power factor while maintaining simplicity, making the system both economical and functionally complete
Solution Approach 2:
The simple system configuration using bridge rectifier, error amplifier, and power converter is self-sufficient in achieving power factor control without requiring external complex sensing or multiplier circuits. The fixed frequency and duty cycle operation inherently provides unity power factor, making the system self-regulating and cost-effective
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 system achieves a unity power factor, reducing operating costs and maintaining a constant current to LEDs, thereby providing efficient and cost-effective lighting solutions for large-scale applications without the need for complex sensing or multiplier circuits.
Implementation Method 1
incorporating a bridge rectifier, error amplifier, and power converter to maintain a constant DC voltage across LEDs
Implementation Method 2
light emitting diodes (LEDs) for a variety of applications
Data Source
AI summary
In one embodiment, an LED system is controlled to have a substantially unity power factor.