LED Constant Current Drive System Power Factor Balance
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Solution Overview
Problem
Existing LED constant current drive systems face challenges in balancing efficiency and power factor, often requiring a trade-off between high efficiency and high power factor, leading to suboptimal performance.
Innovation Solution
The proposed LED constant current drive system includes a storage capacitor that discharges to the LED load when the bus voltage is low, and charges when high, with a charge current control module adjusting the charge voltage based on detection signals from discharge and bus voltage modules, ensuring constant current control and optimizing power factor and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a storage capacitor is connected in parallel to the rectification module to eliminate LED strobing, then the LED output stability is improved, but the power factor of the system decreases
Solution Approach 1:
The patent applies dynamics by making the charge current to the storage capacitor variable rather than constant. The charge current control module dynamically adjusts the charge current based on the difference between the bus voltage and the storage capacitor voltage, enabling the system to adaptively balance between eliminating LED strobing and maintaining power factor.
Solution Approach 2:
The patent changes the parameter of charge current from a fixed value to a dynamically controlled variable. By controlling the charge current based on voltage differences, the system optimizes the charging process to minimize negative impacts on power factor while ensuring the storage capacitor adequately eliminates LED strobing.
2Use of energy by moving object
If a switch transistor is added to control the charge voltage of the storage capacitor and expand the turn-on angle of input current, then the power factor is improved, but the system efficiency decreases
Solution Approach 1:
The patent merges the functions of the switch transistor into the constant current control chip, eliminating the need for an external switch transistor. This integration reduces component count and system complexity while maintaining the ability to control charge voltage and improve power factor.
Solution Approach 2:
The patent dynamically controls the charge voltage parameter of the storage capacitor through the charge current control module. By adjusting the charge voltage based on the difference between bus voltage and storage capacitor voltage, the system expands the turn-on angle of input current to improve power factor while minimizing energy losses.
3Power
If the input voltage is high to ensure adequate voltage headroom for LED operation, then the LED forward voltage requirement is met, but the system efficiency decreases due to excessive voltage drop across the constant current control transistor
Solution Approach 1:
The patent applies preliminary action by pre-charging the storage capacitor during the voltage difference period. The storage capacitor is charged in advance when the bus voltage is significantly higher than the LED forward voltage, storing energy that can be used later when the bus voltage drops, thereby reducing the voltage burden on the constant current control transistor and improving efficiency.
Solution Approach 2:
The storage capacitor acts as an intermediary energy storage element between the rectification module and the LED load. It mediates the voltage difference by storing excess energy when bus voltage is high and releasing it when bus voltage is low, reducing the voltage drop across the constant current control transistor and improving overall system efficiency.
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 eliminates LED strobing, reduces charge current during high bus voltage, and balances power factor and system efficiency, resulting in improved performance and reduced system losses.
Implementation Method 1
a storage capacitor, an upper plate of the storage capacitor is connected with the positive electrode of the LED load; the storage capacitor discharges to the LED load when the bus voltage is less than a voltage on the storage capacitor
Data Source
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AI summary
The present disclosure provides an LED constant current drive system and method, including: a constant current control module, connected with a negative electrode of the LED load; a storage capacitor, which discharges to the LED load when the bus voltage is less than a voltage of the storage capacitor; a discharge voltage detection module, which obtains a control signal by determining a discharge voltage of the storage capacitor based on the negative electrode voltage of the LED load; a bus voltage detection module, which obtains a first detection voltage by detecting the bus voltage; a charge current control module, which adjusts charge voltage of the storage capacitor based on the control signal and the first detection voltage. when the bus voltage is less than the turn-on voltage of the LED, the storage capacitor discharges; when the bus voltage is greater than the turn-on voltage of the LED, the bus voltage supplies power to the LED load, and charges the storage capacitor; when the bus voltage is less than the voltage of the storage capacitor, the storage capacitor discharges. The present disclosure balances the power factor and system efficiency while ensuring that the output LED has no strobing.