LED Driver Phase Control for HID Retrofit Power Factor
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Solution Overview
Problem
Existing LED lamps for retrofitting high-intensity discharge (HID) lamps suffer from poor power factor and harmonic distortion when using a diode bridge to rectify alternating current, leading to overheating and thermal issues due to inefficient power management.
Innovation Solution
An LED driver with a switching arrangement and controller that controls the voltage and phase of alternating input current, allowing bi-directional energy transfer between the input and output nodes, thereby improving power factor and reducing harmonic distortion by adjusting the duty-cycle and phase of the voltage between terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a diode bridge is used to rectify alternating current in existing LED lamps, then the LED load can be powered, but the power factor becomes poor and harmonic distortion is introduced in the mains current
Solution Approach 1:
The patent changes the fundamental operating parameters of the power conversion system by switching from fixed diode bridge rectification to a controllable switching arrangement that can adjust voltage magnitude and phase. This allows the system to operate with improved power factor (near unity) while maintaining low harmonic distortion, directly resolving the contradiction between power factor and harmonic distortion.
Solution Approach 2:
The invention introduces dynamic control capability through the switching arrangement, allowing real-time adjustment of voltage magnitude and phase angle. This dynamic operation enables the system to optimize power factor while minimizing harmonic distortion, unlike the static diode bridge configuration that inherently causes both poor power factor and harmonic distortion.
2Ease of operation
If alternating current is shunted to ground for dimming control, then power consumption can be controlled, but voltage drop across power source elements increases causing overheating
Solution Approach 1:
The patent replaces the passive shunting method with an active switching arrangement that controls power delivery through voltage magnitude and phase angle adjustment. This substitution eliminates the need to shunt current through power source elements, thereby preventing the voltage drop and overheating that occur with shunting-based dimming control.
Solution Approach 2:
Instead of changing current path through shunting, the invention changes voltage parameters (magnitude and phase) to control power delivery to the LED load. This parameter-based control achieves dimming functionality without forcing current through power source elements, thus avoiding thermal issues.
3Reliability
If a diode bridge and buffer capacitor are used for power rectification and storage, then DC output is provided for LED load, but overall system power characteristics deteriorate
Solution Approach 1:
The patent changes the fundamental power conversion approach by replacing diode bridge rectification with a switching arrangement that operates with controlled voltage magnitude and phase. This enables the system to maintain stable DC output for the LED load while achieving superior power characteristics including improved power factor and reduced harmonic distortion.
Solution Approach 2:
The invention introduces dynamic voltage control capability that allows the system to optimize both DC output stability and overall power characteristics simultaneously. The switching arrangement can adaptively adjust voltage parameters to maintain reliable operation while improving power factor and reducing harmonic distortion, unlike the static diode bridge configuration.
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
The solution enables efficient power management, reducing harmonic distortion and overheating, while maintaining optimal power factor and brightness control, meeting international standards like IEC 61000-3-2.
Implementation Method 1
a capacitor connected between the output node and a ground/reference voltage, wherein the capacitor is configured so that, when the LED driver is powered, a voltage across the capacitor is substantially constant
Implementation Method 2
a switching arrangement adapted to controllably connect the first terminal to either the output node or the ground/reference voltage and the second terminal to either the output node or the ground/reference voltage to thereby enable control of a magnitude and phase, relative to a phase of the alternating input current, of the voltage between the first and second terminals
Data Source
AI summary
An LED driver for an LED lamp, which also comprises an LED load. The LED driver is adapted to connect to an input source at a first and second terminal. The LED driver comprises a switching arrangement configured to enable a controller to control at least a magnitude and phase of the voltage between the first and second terminals. The phase of the voltage between the first and second terminals may be defined to control an amount of power that flows from the input source to power the LED lamp.