Linear LED Driver Circuit Active Valley-Fill Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing linear constant current LED driver circuits suffer from low efficiency due to a large voltage difference between the input voltage and the voltage at the LED string, leading to increased power consumption in the N-mosfet, which decreases the overall efficiency of the circuit.
Innovation Solution
The proposed linear constant current LED driver circuit operates in active valley-fill circuit mode, utilizing a diode and capacitor configuration to store energy and dynamically adjust the voltage across N-mosfets, allowing for efficient current delivery through the LED string with reduced ripple and increased efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the voltage difference between input voltage and LED string voltage is large, then the circuit can drive LED strings with different voltage requirements, but the power consumption of the N-mosfet increases and efficiency decreases
Solution Approach 1:
The circuit segments the single N-mosfet constant current load into two parallel paths: one with N-mosfet N1 for direct current regulation, and another with capacitor C1 and diodes D1-D4 for energy storage and ripple compensation. This segmentation allows each component to operate more efficiently, reducing overall power loss while maintaining adaptability to different voltage differences.
Solution Approach 2:
The invention changes the operating parameters of the circuit by introducing a capacitor-based valley-fill mechanism that dynamically adjusts the voltage waveform. The capacitor charges during high-voltage periods and discharges during low-voltage periods, effectively reducing the average voltage difference across the LED string and thereby reducing power consumption in the N-mosfet while maintaining current constant operation.
2Loss of energy
If the number of LED lamps in the LED string is increased, then the voltage difference decreases and efficiency improves, but the cost increases
Solution Approach 1:
The capacitor C1 acts as an intermediary energy storage element that mediates between the input voltage and the LED string. It stores excess energy when input voltage is high and releases it when input voltage is low, effectively reducing the voltage difference across the LED string without requiring additional LEDs. This intermediary mechanism achieves efficiency improvement without increasing the quantity of LED components.
3Loss of energy
If the voltage difference is reduced to improve efficiency, then power consumption decreases, but the ability to drive different LED configurations is reduced
Solution Approach 1:
The circuit dynamically adapts to different operating conditions through the capacitor-based valley-fill mechanism. The capacitor automatically charges and discharges based on the input voltage waveform, dynamically reducing the voltage difference during periods of high voltage while maintaining full adaptability to drive different LED string configurations. This dynamic operation reduces power consumption without sacrificing versatility.
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 configuration improves the overall efficiency of the driver circuit to above 50% without reducing the voltage difference between the input voltage and the LED string voltage, achieving near 100% efficiency during certain stages and maintaining efficiency with smaller ripple throughout the frequency cycle.
Implementation Method 1
a capacitor C1, wherein one end of the capacitor C1 is connected to the anode of the diode D1 and the cathode of the diode D2, and another end of the capacitor C1 is connected to the anode of the diode D3 and the cathode of the diode D4 respectively
Data Source
AI summary
The present invention discloses a linear constant current LED driver circuit in active valley-fill circuit mode comprising a rectifier bridge, a capacitor C1, a diode D1, a diode D2, a diode D3, a diode D4, a LED string and a constant current module. The constant current module comprises a N-mosfet N1, a first operational amplifier, a N-mosfet N2 and a second operational amplifier. During a frequency circle, the LED string can be discharged by firstly charging the capacitor C1 for energy saving through the LED string in constant current and then by the energy stored in the capacitor C1 in constant current, which further ensures that the efficiency of the whole linear constant current driver circuit is improved and the current passing through the LED string has a smaller frequency ripple with a large difference between the DC input voltage and the voltage at two ends of the LED string.