Two-Wire Thyristor Dimmer for High-Efficiency Lamp Control
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Solution Overview
Problem
Existing two-wire dimmer switches struggle to effectively control the intensity of high-efficiency lighting loads like LED and CFL lamps due to impedance characteristics of load regulation devices, which affect conduction time and cause unwanted illumination when off, and require costly microprocessors or neutral connections.
Innovation Solution
A two-wire dimmer switch with a thyristor, gate coupling circuit, and control circuit that conducts gate current independent of load current, using forward phase-control dimming to ensure proper conduction and intensity control, and includes an artificial load circuit to meet thyristor latching and holding current requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing two-wire dimmer switches are used with high-efficiency lighting loads, then the dimmer switch can control the intensity of LED and CFL lamps, but the impedance characteristics of load regulation devices cause unwanted illumination when off and affect conduction time
Solution Approach 1:
An artificial load circuit is introduced as an intermediary component between the thyristor and the high-efficiency lighting load. This artificial load provides a dedicated current path that ensures the thyristor receives sufficient latching and holding currents independent of the actual lighting load characteristics, thereby preventing unwanted illumination and ensuring reliable conduction control.
Solution Approach 2:
The circuit modifies the current parameters by providing an alternative current path through the artificial load. This changes the electrical parameters (current magnitude and timing) delivered to the thyristor gate, ensuring that latching and holding current requirements are met regardless of the lighting load's impedance characteristics, thus eliminating phantom illumination issues.
2Measurement precision
If microprocessors or neutral connections are used to achieve proper control, then intensity control accuracy improves, but device complexity and cost increase
Solution Approach 1:
The invention extracts and removes the complex microprocessor-based control circuits and neutral connection requirements from the dimmer switch design. By using a simplified thyristor-based phase-control approach with an artificial load circuit, the patent achieves effective intensity control without the need for expensive and complex electronic control systems.
Solution Approach 2:
The patent replaces expensive microprocessors and complex control circuits with inexpensive thyristor-based control components. The artificial load circuit uses simple, cost-effective components that provide reliable control functionality without requiring expensive electronics or additional wiring infrastructure.
3Duration of action of moving object
If forward phase-control dimming is used with high-efficiency loads, then conduction time control improves, but the thyristor latching and holding current requirements are not met due to high impedance
Solution Approach 1:
The artificial load circuit serves as an intermediary that decouples the thyristor's current requirements from the high-impedance lighting load. It provides a dedicated low-impedance current path that ensures sufficient latching and holding currents flow through the thyristor during the conduction period, maintaining reliable operation throughout the intended conduction time.
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 dimmer switch provides reliable intensity control for a wide range of lamps with improved noise immunity and reduced susceptibility to cross talk, operating efficiently with high-efficiency loads without neutral connections and advanced control circuits.
Implementation Method 1
a thyristor having first and second main load terminals adapted to be coupled in series electrical connection between an alternating-current (AC) power source and an electrical load for conducting a load current from the AC power source to the electrical load, and a gate that conducts a gate current to render the thyristor conductive
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.