Single Switch LED Driver With LC Filter For High Power Factor
Solution Overview
Problem
Existing LED driver solutions compromise on efficiency, power density, lifetime, and cost, often requiring bulky capacitors and complex architectures to achieve high power factor and low flicker, while single-stage solutions struggle with reliability and size constraints.
Innovation Solution
A single-stage power converter with an integrated preconditioner that uses a low-pass filter and a few components, including a single switching element and energy storage, to achieve high power factor and constant output power, minimizing the need for large capacitors and simplifying the component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-stage power converter architecture is used to achieve high power factor and constant output power, then power factor and output stability are improved, but device complexity and component count increase
Solution Approach 1:
The patent merges the preconditioner stage and power conversion stage into a single integrated stage, eliminating the need for separate two-stage architecture. The single switching element performs both power factor correction and voltage conversion functions simultaneously, reducing component count while maintaining high power factor and stable output power delivery to the LED load
2Device complexity
If a single-stage power converter is used to reduce complexity and component count, then device complexity is reduced, but output power stability and reliability deteriorate
Solution Approach 1:
The patent employs dynamic control of the single switching element to maintain constant output power despite variations in input voltage and load conditions. The switching duty cycle is dynamically adjusted based on feedback to ensure stable LED operation, achieving reliability comparable to two-stage solutions while maintaining single-stage simplicity
3Reliability
If a bulky low frequency storage capacitor is used to guarantee constant output power delivery, then output power stability is improved, but device size and weight increase
Solution Approach 1:
The patent changes the operating parameters by using high frequency switching instead of low frequency operation. This allows the use of smaller ceramic or film capacitors with equivalent energy storage capability at higher frequencies, dramatically reducing the size and weight of the storage capacitor while maintaining constant output power delivery to the LED load
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 high power factor, small size, long lifetime, and low cost, while reducing perceptible flicker and component count, enabling efficient operation across varying load and voltage ranges with reduced complexity and size.
Implementation Method 1
a filter capacitor (Cs) coupled between a low voltage terminal of the filter unit and a second power output terminal
Implementation Method 2
a filter inductor (Lc) coupled between a high voltage terminal of the filter unit and a first power output terminal
Implementation Method 3
an energy storage element (Ch) coupled between the switch node and an intermediate node
Data Source
Figure 1~2a
Figure 2b
Figure 3a~3b
AI summary
The present invention relates to a driver device (50a-50f) and a corresponding method for driving a load (22), in particular an LED unit comprising one or more LEDs (23). The proposed driver device comprises power input terminals (51, 52) for receiving a rectified supply voltage from an external power supply, power output terminals (53, 54) for providing a drive voltage and/or current for driving a load (22), a single stage power conversion unit (66a, 66b, 66c) coupled to the power input terminals (52) comprising a single switching element (60) and an energy storage element (Ch), both coupled to a switch node (55), wherein the power output terminals (53, 54) are represented by the output of said stage power conversion unit, a filter unit (68) coupled to said switch node (55), said filter unit comprising a filter inductor (Lc) and a filter capacitor (Cs), and a control unit (58) for controlling said switching element (60).