Single-Stage LED Driver Circuit with Linear Regulator
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Solution Overview
Problem
Existing circuit topologies for operating semiconductor light sources, such as LEDs, are complex and expensive due to the combination of two switching regulators, and simplification proposals, like replacing the step-down converter with a linear regulator, are limited by high output voltages from step-up converters, making it difficult to achieve efficient and cost-effective power delivery.
Innovation Solution
A circuit arrangement featuring a single-stage converter with a SEPIC or boost converter for power factor correction, combined with a linear regulator, where the linear regulator no longer compensates for the ripple voltage at the minimum output voltage, allowing current modulation in the load current, and utilizing a storage capacitor with a voltage divider for optimal control and temperature regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-stage converter topology (step-up converter + step-down converter) is used, then power factor correction and current regulation are achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the step-up converter and step-down converter into a single integrated converter stage, eliminating the need for separate power factor correction and current regulation stages. This single-stage converter performs both functions simultaneously, reducing device complexity and manufacturing cost while maintaining reliable power factor correction.
Solution Approach 2:
The single-stage converter is designed to perform multiple functions: it provides power factor correction, voltage conversion, and current regulation all in one circuit stage. This multi-functional design replaces the traditional two-stage topology, simplifying the overall device structure without compromising performance.
2Device complexity
If the step-down converter is replaced with a linear regulator, then device complexity is reduced, but the high output voltage from the step-up converter makes it difficult to operate semiconductor light sources
Solution Approach 1:
The patent combines the voltage conversion and current regulation functions into a single converter stage that directly outputs a current suitable for semiconductor light sources. This integrated approach avoids the high voltage output problem of traditional step-up converters followed by linear regulators, as the single stage is designed to deliver the appropriate voltage and current levels directly.
3Stability of the object's composition
If the linear regulator compensates for ripple voltage at minimum output voltage, then current uniformity is improved, but component utilization is suboptimal and installation space increases
Solution Approach 1:
The patent introduces dynamic headroom control that allows the linear regulator to adapt its operation based on the instantaneous output voltage conditions. During voltage minima, the headroom is increased to maintain current uniformity, while during normal operation, the headroom is reduced to minimize power loss and optimize component utilization. This dynamic adjustment maintains current stability without requiring excessive installation space.
Solution Approach 2:
The system dynamically changes the headroom parameter of the linear regulator based on the output voltage ripple conditions. By adjusting the headroom voltage in response to voltage minima, the system maintains uniform current through the semiconductor light sources while optimizing the utilization of available components and reducing the required installation space.
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 design optimizes component utilization, reduces installation space and costs, enables efficient power delivery to LEDs with minimal loading of the linear regulator, and provides effective temperature protection, achieving higher power delivery with reduced component dimensions.
Implementation Method 1
a converter circuit, a clocked converter circuit (71) which converts the mains input AC voltage rectified by the converter circuit into an output voltage
Implementation Method 2
a linear regulator circuit which sets a predetermined load current across the load, the load current being a direct current having a uniform current magnitude
Data Source
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AI summary
The invention relates to a circuit arrangement for operating a load, comprising an input for supplying an alternating system input voltage, a rectifier circuit, a converter circuit which converts the alternating system input voltage rectified by the rectifier circuit into an output voltage, a control circuit for controlling the converter circuit, and a linear regulating circuit which sets a predefined load current on the load, said load current being a direct current. The control circuit controls the converter circuit in such a way that the intensity of the load current is reduced when the output voltage is at a minimum.