Phase Chopping Control for LED Lamps with Low-Magnetostriction Inductor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing phase control dimmers for low-energy loads like LED lamps suffer from flickering, ghosting, and noise issues due to their design, which is inadequate for the lower power requirements of these loads, leading to suboptimal performance and increased hum.
Innovation Solution
A phase control system using a coil with a high-quality, low-magnetostriction core and a reduced capacitance interference suppression capacitor, optimized for thyristor control, which minimizes noise and ensures stable operation even at low loads by using a high-inductance coil and low-capacitance capacitor, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coil with low Q factor and high loss factor is used as inductor, then the latching and holding current of the triac remains constant despite low applied load, but this causes noticeable hum or buzzing noise
Solution Approach 1:
The patent changes the Q factor parameter of the inductor from low to high, and adjusts the capacitance of the suppression capacitor from typical values to specifically less than 35 nF. This parameter change resolves the contradiction by allowing constant latching and holding current while eliminating the hum associated with low Q factor coils.
Solution Approach 2:
The patent applies different quality characteristics to different components: the inductor is designed with high Q factor (low loss) while the suppression capacitor is designed with specifically low capacitance (<35 nF). This local differentiation of component qualities allows the system to achieve both stable triac operation and low noise performance.
2Illumination intensity
If phase-angle control is used to dim low-energy loads, then brightness adjustment is achieved, but flickering occurs because the latching current is insufficient at low loads
Solution Approach 1:
The patent changes the inductance parameter by using a coil with high Q factor and high inductance, which provides sufficient latching current even at low load conditions. This parameter change enables reliable phase-angle control without flickering while maintaining brightness adjustment capability.
3Object-affected harmful factors
If a suppression capacitor with capacitance of 100 nF is used, then radio interference suppression is achieved, but this contributes to hum generation at medium dimming settings
Solution Approach 1:
The patent changes the capacitance parameter of the suppression capacitor from typical values (e.g., 100 nF) to specifically less than 35 nF. This parameter change reduces the capacitor's contribution to hum generation while maintaining adequate radio interference suppression through the combined effect of the high Q factor inductor and low capacitance capacitor.
Data Source
Figure 1
AI summary
A two-wire phase-angle control for a low-energy consumer, such as an LED lamp 2, comprises an electronic power control with an inductance provided by a core-enclosed coil 14 and with a suppression capacitor 15. The electronic power control is implemented as a thyristor control with two antiparallel thyristor circuits, each with at least one thyristor 4, 4.1. The coil core of the inductor 14 is made of a low-magnetostriction or magnetostriction-free material.