LED Driver Circuit Dynamic String Control
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Solution Overview
Problem
Conventional AC direct drive LED circuits waste significant power in the driver circuitry, leading to inefficient light output and excessive heat generation, as they operate with a fixed length LED string and constant current regulator, which limits the utilization of input energy.
Innovation Solution
A circuit that dynamically controls multiple strings of LEDs by switching them on and off based on the input voltage, using a controller to vary the number of conducting strings, thereby optimizing power dissipation and increasing light output duty cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed length LED string is driven by a constant current regulator, then the LED string operates at full load within a very short time, but significant power is wasted in the driver circuitry
Solution Approach 1:
The LED string is divided into multiple segments with different forward voltage thresholds. The controller selectively activates different segments based on the instantaneous input voltage level, allowing the system to operate efficiently across varying voltage conditions rather than wasting power in a fixed configuration
Solution Approach 2:
The system dynamically adjusts which LED segments are active based on real-time voltage conditions. The controller continuously monitors input voltage and switches between different LED string configurations to optimize power utilization and minimize driver circuitry power waste throughout the AC cycle
2Duration of action of moving object
If LEDs with higher or lower turn-on voltages are selected, then different on times for the LED can be obtained, but the amount of power wasted in the driver circuit is also affected
Solution Approach 1:
The system changes the electrical parameters of the LED circuit by switching between segments with different forward voltage characteristics. This allows optimization of both LED on-time duration and driver power efficiency by matching segment selection to instantaneous voltage conditions
3Use of energy by moving object
If the LED board produces more light for a given number of LEDs, then energy efficiency improves, but heat generation must be managed
Solution Approach 1:
The system converts what would be wasted driver circuitry power into useful light output by utilizing multiple LED segments with different voltage thresholds. This improves overall energy efficiency while the distributed segment operation helps distribute heat generation more evenly across the board
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 approach reduces power wastage in the driver circuit, increases light output, and minimizes heat generation, allowing for more efficient energy use and potentially smaller or no heat sinks, while maintaining compatibility with standard dimmer switches.
Implementation Method 1
The CCR is an electronic circuit that regulates the current running through it independent of the voltage applied This arrangement operates by rectifying an AC input. After the AC input is rectified, the resulting DC output is a half pulse sinusoidal voltage curve at 120 Hz.
Implementation Method 2
Light emitting diodes (LEDs) are solid state devices that convert electric energy to light, and generally include one or more active layers of semiconductor material sandwiched between oppositely doped layers. When bias is applied across doped layers, holes and electrons are injected into one or more active layers where they recombine to generate light that is emitted from the device.
Data Source
AI summary
A method and circuit for driving an LED lighting device from an AC power source includes a rectifier and a plurality of strings of LEDs. Each string of LEDs includes a plurality of LEDs. A plurality of switches is controlled by a controller for opening and closing the switches. The controller is adapted to vary the number of strings conducting electricity by applying voltage from the rectifier to arrangements of the plurality of strings of LEDs selected based upon the present voltage of the output of the rectifier and the forward bias voltage of each of the strings of LEDs.