Two-Wire Dimmer Thyristor Control for High-Efficiency Lighting
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Solution Overview
Problem
Existing dimmer switches struggle to effectively control the intensity of high-efficiency lighting loads like LED and CFLs, as they often require neutral connections and advanced control circuits, leading to inefficiencies and increased costs, and are unable to handle low-power ratings effectively.
Innovation Solution
A two-wire load control device using a thyristor with a gate coupling circuit and control circuit that conducts a gate current through MOS-gated transistors to control the thyristor's conduction time, allowing for precise power delivery to high-efficiency lighting loads without requiring a neutral connection, using either forward or reverse phase-control dimming techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If prior art two-wire dimmer switches are used to control high-efficiency lighting loads, then the device complexity is reduced by eliminating neutral connections, but the ability to effectively control low-power loads is lost
Solution Approach 1:
The patent introduces an artificial load circuit as an intermediary component that compensates for the low power factor of high-efficiency lighting loads. This artificial load provides the necessary reactive power and minimum load current to enable reliable thyristor operation, effectively mediating between the dimmer switch and the high-efficiency load to resolve the control effectiveness issue while maintaining the two-wire simple structure
2Measurement precision
If advanced control circuits are used to control high-efficiency lighting loads, then the control precision is improved, but the cost and device complexity increase
Solution Approach 1:
The patent changes the operating parameters of the thyristor by introducing an artificial load that provides minimum load current and appropriate power factor. This parameter change enables the use of simple forward phase-control dimming with basic components while achieving effective control of high-efficiency loads, thereby maintaining control precision without increasing device complexity or cost
3Ease of manufacture
If forward phase-control dimming is used with high-efficiency loads, then the ease of manufacture is improved, but the ability to maintain desired intensity levels is compromised
Solution Approach 1:
The artificial load circuit acts as an intermediary that corrects the power factor and provides minimum load current, enabling forward phase-control dimming to accurately maintain desired intensity levels with high-efficiency loads while keeping the manufacturing process simple and cost-effective
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
Enables precise control of high-efficiency lighting loads with reduced costs and improved efficiency by eliminating the need for neutral connections and advanced control circuits, effectively managing low-power ratings and maintaining desired intensity levels.
Implementation Method 1
The control circuit is configured to control the gate coupling circuit to cause the MOS-gated transistors to conduct the gate current through the gate terminal of the thyristor to thus render the thyristor conductive at a firing time during a present half cycle of the AC power source
Implementation Method 2
The dimmer switch typically comprises a bidirectional semiconductor switch, e.g., a thryristor (such as a triac) or two field-effect transistors (FETs) in anti-series connection. The bidirectional semiconductor switch is coupled in series between the AC power source and the load and is controlled to be conductive and non-conductive for portions of a half cycle of the AC power source
Data Source
AI summary
A two-wire load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit coupled between a first main load terminal and the gate of the thyristor, and a control circuit coupled to a control input of the gate coupling circuit. The control circuit generates a drive voltage for causing the gate coupling circuit to conduct a gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, and to allow the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle, where the gate coupling circuit conducts approximately no net average current to render and maintain the thyristor conductive.