LED Driver Power Factor Correction Using Merged Control Circuitry
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Solution Overview
Problem
Existing LED driver systems with power factor correction (PFC) require multiple components, are costly, and inefficient due to the need for DC conversion and current measurement, and face compatibility issues with pre-existing electronic transformers designed for halogen lamps, as LEDs draw less power and have different current requirements.
Innovation Solution
A control circuit block with a switching device and waveform shaper, such as an inductor, measures and controls the input current to be in phase with the main power source, eliminating the need for current measurement in the LED array and improving peak current, thus achieving PFC and enhancing compatibility with electronic transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If existing LED driver systems with power factor correction are used, then power factor correction is achieved, but the system requires multiple components, is costly, and has high device complexity
Solution Approach 1:
The patent combines the power factor correction functionality with the existing LED driver circuit by utilizing the same switching device and control circuitry. The switching device that already exists for LED control is also employed for PFC, eliminating the need for separate PFC components and reducing overall system complexity while achieving both LED driving and power factor correction functions
Solution Approach 2:
The control circuit and switching device are designed to perform multiple functions: they simultaneously control the LED current and provide power factor correction. The same control circuitry that regulates LED operation also manages the switching waveform to achieve PFC, making the system multi-functional and reducing component requirements
2Ease of manufacture
If existing LED driver systems with power factor correction are used, then power factor correction is achieved, but the system is costly
Solution Approach 1:
The patent merges the PFC function with the LED driver circuit, eliminating the need for separate PFC components. By using the existing switching device and control circuitry for both LED control and PFC, the system reduces component count and associated costs while maintaining effective power factor correction
Solution Approach 2:
The existing LED driver circuit components serve dual purposes: they perform their primary LED control function while simultaneously providing power factor correction. The switching device and control circuitry self-service the PFC requirement without needing additional dedicated components, reducing overall system cost
3Productivity
If existing LED driver systems are used, then LED operation is achieved, but the system is inefficient due to DC conversion requirements
Solution Approach 1:
The patent employs periodic switching action at the line frequency to achieve power factor correction. The switching device operates in sync with the AC input waveform, periodically adjusting the current draw to match the voltage waveform and maintain a resistive load appearance, thereby improving efficiency without requiring full DC conversion
4Adaptability or versatility
If existing LED driver systems are used, then LED operation is achieved, but the system faces compatibility issues with pre-existing electronic transformers designed for halogen lamps
Solution Approach 1:
The patent modifies the current waveform parameters to be compatible with pre-existing electronic transformers. By shaping the current waveform to appear resistive and in-phase with the voltage, the system mimics the load characteristics that electronic transformers expect from halogen lamps, thereby ensuring compatibility while driving LEDs
Solution Approach 2:
The switching device and waveform shaping circuitry act as an intermediary between the LED driver and the electronic transformer. This intermediary component modifies the electrical characteristics of the load to be compatible with the transformer's expectations, enabling seamless integration without requiring transformer replacement
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 reduces component count and operational inefficiencies, maintains efficiency by minimizing DC conversion, and ensures compatibility with electronic transformers by maintaining a resistive load and improving peak current, enabling effective power factor correction and efficient LED operation.
Implementation Method 1
A waveform shaper, such as an inductor, is positioned to modify an AC signal prior to being converted into a rectified DC signal. This waveform shaper improves the peak current on the AC power signal while maintaining its average current.
Implementation Method 2
A waveform shaper, such as an inductor, is positioned to modify an AC signal prior to being converted into a rectified DC signal
Implementation Method 3
an LED array, which comprises a plurality of light emitting diodes (LEDs), each LED in the array being powered by the driver circuit
Data Source
AI summary
Various embodiments of the invention provide power factor correction in solid state lighting applications. In certain embodiments, an LED driver for an LED array is controlled for power factor correction by a control circuit block. The control circuit block comprises electronic circuitry that enables the input current to the LED driver to be measured and controlled. This control circuit block comprises at least one switching device that enables an alternating form of current at a particular frequency to be applied to the LED array regardless of whether the main power source is a DC or AC power source.