Lighting Ballast as Constant-Current Driver for LED Arrays
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Solution Overview
Problem
Existing lighting systems face challenges in efficiently powering constant voltage DC loads, particularly with high-intensity discharge lamps, as they require complex driver circuits to manage varying power inputs and thermal protection, which increases complexity and cost.
Innovation Solution
A lighting ballast is configured to operate as a constant-current source, utilizing existing power processing functions to simplify the driver circuit, and incorporates a rectifier element and a thermostat for thermal protection, allowing it to power LED strings by matching the rectified voltage output range and providing thermal safety features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a complex driver circuit is used to power constant voltage DC loads, then power management capability is improved, but device complexity increases
Solution Approach 1:
The patent merges the driver circuit functionality with the existing ballast by incorporating the driver electronics inside the ballast housing. The ballast's existing power processing functions are utilized to reduce overall system complexity while maintaining constant voltage DC power management capability for LED loads.
Solution Approach 2:
The ballast is designed to perform multiple functions: it serves as both the traditional power regulation device for HID lamps and as a driver for constant voltage DC LED loads. The circuit can operate in different modes depending on the connected load, providing universal compatibility across different lighting technologies.
2Reliability
If thermal protection features are added to the lighting system, then reliability is improved, but device complexity increases
Solution Approach 1:
The system incorporates a thermostat that automatically monitors temperature and opens the circuit when overheating is detected, providing self-protecting functionality without requiring complex external control systems. This simple yet effective thermal protection mechanism enhances reliability while minimizing added complexity.
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 reduces the complexity of driver electronics, ensures efficient power management, and provides thermal protection, enabling cost-effective and reliable operation of LED lamps in existing lighting fixtures, including HID lamps, and supports various power sources including batteries and AC inputs.
Implementation Method 1
coupled to an input 105 of a rectifier element 102
Data Source
AI summary
Apparatus and associated methods relate to powering a constant voltage DC load using a rectified output of a lighting ballast. In an illustrative example, the ballast may be configured to operate as a constant-current source. The DC load may, for example, comprise an array of LED strings connected in parallel. The number of LED strings may, for example, be selected to match a power output of the ballast. The number of LEDs in each string may, for example, be selected to match a rectified voltage output range of the ballast. A normally-open thermostat may, for example, be connected in parallel between the ballast and a rectifier and be configured to short-circuit the ballast if the circuit overheats. Various embodiments may advantageously utilize existing power processing functions of an electronic ballast to reduce complexity of a driver circuit for a constant voltage DC source.