Dynamic Current Source for LED Power Factor Correction
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Solution Overview
Problem
Existing LED-based lighting units driven directly from the mains power supply face issues with low power factor and excessive in-rush currents, leading to reduced efficiency and potential circuit breaker triggering, especially when initially turned on.
Innovation Solution
A dynamically modulated current source is used in series with a capacitor to shape the capacitor current, improving the power factor and reducing peak power dissipation, while limiting input current to prevent circuit breaker activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rectifier circuit and capacitor are connected to drive LED load directly from mains power supply, then the LED load can operate with AC and DC input, but the current waveform has high peak values compared to average value resulting in low power factor and reduced efficiency
Solution Approach 1:
The patent applies dynamics by making the capacitor value variable rather than fixed. The system dynamically adjusts the capacitor value based on operating conditions (AC or DC input, startup state, load conditions) to optimize power factor and limit in-rush current. This resolves the contradiction by adapting the circuit parameters in real-time rather than being fixed for all conditions.
Solution Approach 2:
The patent changes the parameter of capacitor value dynamically. By switching between different capacitor values or using variable capacitance, the system optimizes the charging current waveform to improve power factor while maintaining AC/DC versatility. This parameter change allows the system to achieve both adaptability and energy efficiency.
2Stability of the object's composition
If a capacitor is connected in parallel with LED load for power factor control, then smoothing is improved, but high current peaks occur during capacitor recharging resulting in low power factor
Solution Approach 1:
The patent makes the capacitor value dynamic rather than static. By adjusting capacitance based on the charging state and load conditions, the system provides sufficient smoothing while controlling the charging current peaks. This dynamic adjustment resolves the contradiction between maintaining voltage stability and avoiding high current peaks that reduce power factor.
Solution Approach 2:
The patent implements periodic control of the capacitor charging process. By controlling when and how the capacitor charges (using periodic switching or controlled charging cycles), the system smooths voltage while distributing current draw over time rather than allowing large instantaneous peaks, thereby improving power factor.
3Object-affected harmful factors
If resistor limits capacitor charging current, then in-rush current is controlled, but excessive voltage drop occurs and nominal LED operation current is reduced
Solution Approach 1:
The patent replaces the static resistor with a dynamic capacitor-based current limiting approach. The capacitor value is adjusted based on operating conditions to provide appropriate current limiting during startup without causing excessive voltage drop during normal operation. This dynamic adjustment allows the system to protect against in-rush current while maintaining adequate LED operating current.
Solution Approach 2:
The patent uses a controlled capacitor as an intermediary between the power supply and LED load. This intermediary element provides current limiting functionality during startup without the continuous voltage drop associated with a series resistor. The capacitor charges in a controlled manner, limiting in-rush current while allowing full power delivery to LEDs during normal operation.
4Productivity
If multiple LED lighting units are connected to one circuit, then total current draw increases, but excessive current triggers magnetic release of circuit breaker
Solution Approach 1:
The patent implements dynamic current limiting through variable capacitor control. By adjusting capacitance based on startup conditions and load state, the system limits in-rush current peaks that would otherwise trigger circuit breakers. This allows multiple lighting units to be connected without excessive total current draw, improving productivity while maintaining circuit breaker reliability.
Solution Approach 2:
The patent applies preliminary action by controlling the capacitor charging process before full power is delivered to the LEDs. This preliminary controlled charging phase limits in-rush current and prevents circuit breaker triggering, allowing the system to safely connect multiple units. Once charging is complete, full power is delivered for normal operation.
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 enhances the power factor and efficiency of LED lighting units, preventing excessive in-rush currents and ensuring compliance with high power factor regulations, thereby reducing the risk of circuit breaker triggering and improving overall performance.
Implementation Method 1
a capacitor may be connected in parallel with the LED load within the lighting unit... acts as a power factor control (PFC) and smoothing circuit
Implementation Method 2
The current source is configured to modulate dynamically an amplitude of an input current provided to the parallel arrangement of the capacitor and the solid state lighting load based on an input voltage
Data Source
AI summary
A device for controlling current to a solid state lighting load includes a capacitor (241, 341) and a current source (245, 345). The capacitor is connected in a parallel arrangement with the solid state lighting load (260, 360). The current source is connected in series with the parallel arrangement of the capacitor and the solid state lighting load. The current source is configured to modulate dynamically an amplitude of an input current provided to the parallel arrangement of the capacitor and the solid state lighting load based on an input voltage.