Magnetic Amplifier LED Driver Circuit for Current Stability
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Solution Overview
Problem
Conventional lighting systems, particularly those using solid-state light sources like LEDs, face inefficiencies in power management, leading to variations in light output and potential damage due to constant voltage converters, which do not account for temperature-induced changes in forward voltage drops.
Innovation Solution
The implementation of a magnetic amplifier-based drive circuit with control windings, power windings, and a rectifier to convert alternating current to direct current, coupled with a feedback circuit and power factor correction mechanisms, ensures stable current flow and reduces electromagnetic interference, enhancing energy efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant voltage converter is used to power solid-state light sources, then the light source can operate with simplified power supply, but small variations in forward voltage due to temperature changes result in large variations in current through the light source
Solution Approach 1:
The patent implements a feedback circuit that senses the current through the solid-state light source and adjusts the power converter output to maintain constant current. The feedback mechanism includes a sense resistor that measures current and a control circuit that regulates the power converter based on the sensed value, ensuring stable operation despite temperature variations in forward voltage.
Solution Approach 2:
The patent replaces the conventional constant voltage power supply approach with a constant current power supply system using a power converter (switching regulator). This substitution fundamentally changes the control mechanism from voltage-based to current-based, eliminating the problem of current variations caused by forward voltage changes.
2Use of energy by moving object
If higher efficiency light sources like solid-state LEDs are used, then energy efficiency is improved, but they require complex power converters to operate off AC lines and need constant current control
Solution Approach 1:
The patent combines multiple functions into a single integrated power converter unit. The converter simultaneously performs AC rectification, voltage regulation, and constant current control for the LED array. This merging eliminates the need for separate power supply components and simplifies the overall system architecture while maintaining high efficiency.
Solution Approach 2:
The power converter is designed as a universal solution that can drive multiple solid-state light sources in series or parallel configurations. The single converter unit adapts to different LED array configurations and AC voltage inputs, providing multi-functional capability that reduces system complexity.
3Area of stationary object
If multiple luminaires are spaced at intervals to provide minimum overall illumination, then coverage area is improved, but total energy consumption increases
Solution Approach 1:
The patent enables independent control of current through each luminaire or group of luminaires by providing separate power converter units. This allows adjustment of operating parameters (current levels) to optimize illumination efficiency, maintaining minimum required coverage while reducing total energy consumption through parameter optimization.
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 solution provides stable and efficient power delivery to solid-state light sources, minimizing light output variations and extending their operational life while reducing electromagnetic interference and energy consumption.
Implementation Method 1
the control circuit controls a flow of direct current through the one or more control windings which causes a biasing magnetic flux in the one or more magnetic cores
Implementation Method 2
the one or more power windings which in operation receive alternating current from an alternating current supply
Implementation Method 3
a rectifier electrically coupled to the one or more power windings and to the plurality of solid-state light sources, wherein in operation the rectifier provides a direct current to drive the plurality of solid-state light sources
Implementation Method 4
a plurality of solid-state light sources electrically coupled to the one or more power windings
Data Source
AI summary
Systems, methods and articles for providing lighting or illumination systems having drive circuits that employ a magnetic amplifier (“mag-amp”) and one or more feedback circuits to form a power converter that powers solid-state light sources (e.g., LEDs). The magnetic amplifier includes one or more magnetic cores which provides a controllable reluctance for magnetic flux. The magnetic amplifier includes one or more power windings which receive energy from an alternating current (AC) supply (e.g., AC mains) and delivers rectified AC current as direct current (DC) to one or more solid-state light sources. The magnetic amplifier includes one or more control windings coupled to a DC control source. The drive circuit may have two or more rectifiers (e.g., solid-state rectifiers) to provide a direct current to drive the solid-state light sources and also to isolate the one or more control windings from interference from the magnetic flux of the one or more power windings.