LED Illumination Device with Feedback-Controlled AC to DC Power Converter
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Solution Overview
Problem
Existing LED conversion systems for AC to DC power are impractical due to their size and cost, especially when operating at higher voltages, making them unsuitable for all LED applications.
Innovation Solution
A power converter with a switching element and feedback circuit that adjusts the duty cycle to control the output current through LEDs, allowing operation at a low-voltage, high-current point, minimizing component count and power dissipation, and enabling advanced controls like dimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If known converters are used for AC to DC power conversion, then power supply function is achieved, but device size and cost increase due to larger passive components at higher voltages
Solution Approach 1:
The patent changes the operating voltage parameter by operating the converter at a low-voltage, high-current point rather than traditional high-voltage, low-current operation. This parameter change allows the use of smaller passive components (capacitors and inductors) since their size is directly related to the operating voltage level, thereby reducing overall device size while maintaining power supply function
Solution Approach 2:
The patent employs dynamic control through a feedback circuit that continuously adjusts the duty cycle of the switching element based on output current feedback. This dynamic adjustment enables the converter to maintain stable operation at the optimized low-voltage, high-current operating point, adapting to load changes while keeping component sizes minimal
2Power
If known converters are used for AC to DC power conversion, then power supply function is achieved, but device cost increases due to larger passive components
Solution Approach 1:
By changing the operating voltage parameter to a low-voltage, high-current mode, the patent reduces the size and cost of passive components. Capacitors and inductors are significantly smaller and less expensive at lower voltage ratings, directly reducing manufacturing costs while maintaining the required power supply function
Solution Approach 2:
The feedback circuit monitors output current and dynamically adjusts the switching duty cycle to maintain optimal operation. This feedback control enables the system to operate efficiently at the cost-optimized low-voltage point, ensuring stable performance without requiring expensive oversized components that would be needed in open-loop or traditional high-voltage designs
3Power
If conventional ballast and rectifier circuit are used, then AC to DC conversion is achieved, but component count and complexity increase
Solution Approach 1:
The patent merges the functions of the conventional ballast and rectifier circuit into a single integrated switching converter. The switching element and feedback circuit replace the separate ballast and rectifier components, consolidating multiple functions (power factor correction, rectification, and regulation) into one unified circuit, thereby reducing component count and overall system complexity
Solution Approach 2:
The switching converter is designed to perform multiple functions simultaneously: it acts as a rectifier, a ballast, and a power regulator all in one circuit. This multi-functional design eliminates the need for separate dedicated components for each function, reducing complexity while achieving the same AC to DC conversion and LED control objectives
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 enables efficient and cost-effective conversion of AC to DC power for LEDs, allowing for smaller and less expensive components, and provides advanced control features such as dimming, which is not possible with existing systems.
Implementation Method 1
the PWM switching circuit receives the DC power and pulse-width modulates the DC power to supply an LED array
Implementation Method 2
The feedback circuit is configured to increase the value of the duty cycle to decrease an output current signal through the at least one LED and to decrease the value of the duty cycle to increase the output current signal through the at least one LED
Data Source
AI summary
Disclosed herein is an illumination device having at least one LED and a power converter with a switching element for connection to an existing fluorescent lamp fixture including a conventional ballast. The illumination device includes a feedback circuit operable to provide a switching signal to the switching element according to a duty cycle, the feedback circuit configured to: increase the value of the duty cycle to decrease an output current signal through the at least one LED; and decrease the value of the duty cycle to increase the output current signal through the at least one LED.