LED Driving Apparatus with Dynamic Bypass for AC Rectified Voltage
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Solution Overview
Problem
Existing LED driving circuits face challenges in achieving high operation efficiency and power factor while maintaining high power supply efficiency, due to the variability in forward directional voltages and temperature characteristics of LEDs, especially when using AC power, which leads to inefficient light emission and increased heat generation.
Innovation Solution
A light-emitting diode driving apparatus that includes a rectifying circuit and multiple LED blocks connected in series, with switching portions that control the bypassing of LED blocks based on current levels, allowing for efficient power usage and optimized light emission independent of pulsating current voltage variations, and incorporating current controlling and detecting portions to manage current flow and restrict excessive current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If AC power is used to drive LEDs without smoothing the rectified voltage waveform, then the circuit can be simplified and size reduced, but the LED operation efficiency decreases due to limited emission time
Solution Approach 1:
The patent divides the LED array into multiple series-parallel connected groups, allowing selective activation of different LED segments based on the instantaneous rectified voltage level. This segmentation enables the system to operate efficiently across the varying voltage waveform without requiring complex smoothing circuits, thus resolving the contradiction between circuit simplicity and operational efficiency.
Solution Approach 2:
The patent employs dynamic switching mechanisms that adjust the configuration of LED connections (series/parallel arrangements) in real-time according to the rectified voltage waveform. This dynamic reconfiguration allows the system to maintain optimal operation efficiency throughout the AC cycle while keeping the overall circuit structure simple and component-count low.
2Loss of energy
If multiple LED blocks are connected in series to match the peak rectified voltage, then power supply efficiency improves, but LED operation efficiency decreases due to limited conduction angle
Solution Approach 1:
The patent segments the LED load into multiple blocks that can be independently switched. By activating different numbers of LED blocks in series based on the instantaneous voltage level, the system maintains high power supply efficiency (by matching voltage levels) while ensuring adequate operation efficiency (by keeping the conduction angle substantial through selective block activation).
Solution Approach 2:
The patent dynamically changes the effective series voltage threshold by altering the configuration of LED blocks (activating different numbers of blocks in series). This parameter change allows the system to adapt to the varying rectified voltage waveform, maintaining both high power supply efficiency and adequate LED operation efficiency across different points in the AC cycle.
3Device complexity
If forward directional voltage variations of LEDs are not compensated, then the circuit remains simple, but current distribution becomes unstable and exceeds LED ratings
Solution Approach 1:
The patent incorporates current detection circuits that monitor the actual current flowing through LED blocks and provide feedback to the switching control mechanism. This feedback enables the system to adjust the switching timing and duration to compensate for forward voltage variations among LEDs, ensuring stable current distribution and preventing excessive current that could damage LEDs, while maintaining relatively simple circuit architecture.
Solution Approach 2:
The patent uses preliminary detection of the rectified voltage waveform characteristics to pre-determine the optimal switching timing for LED blocks. By anticipating the voltage level and predicting the appropriate switching point before the actual current surge occurs, the system can proactively compensate for LED forward voltage variations, ensuring stable current distribution without requiring complex real-time adjustment circuits.
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 improves LED operation efficiency and power factor, reduces heat generation, and provides stable operation by effectively managing current flow and bypassing LED blocks, thus enhancing the reliability and cost-effectiveness of the LED driving apparatus.
Implementation Method 1
a rectifying circuit (2), connected to AC power supply, and rectifies an AC voltage of the AC power supply to provide a pulsating voltage
Data Source
AI summary
A LED driving apparatus includes a rectifying circuit, first, second and third blocks, and first and second switching portions. The rectifying circuit is connected to AC power supply, and rectifies AC voltage of the AC power supply to provide pulsating current voltage. Each block includes a plurality of LEDs. The first, second and third blocks are serially connected to the output side of the rectifying circuit. The first switching portion switches ON/OFF of a first bypass path based on flowing current amount in the first block. The first bypass path bypasses the second block. The second switching portion switches ON/OFF of a second bypass path based on flowing current amount in the first and second blocks. The second bypass path bypasses the third block.