Two-Wire Electronic Switch Asynchronous Power Supply
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Solution Overview
Problem
Existing two-wire electronic switches face challenges in properly controlling AC power delivery to electrical loads due to voltage limitations and inappropriate operation caused by power supply charging mechanisms, particularly affecting lighting loads and compact fluorescent lamps.
Innovation Solution
A two-wire electronic switch design incorporating a controllably conductive device, a controller, an output capacitor, and an in-line power supply that charges asynchronously with respect to the AC power source frequency, allowing the switch to operate with minimal voltage drop and manage load current effectively, ensuring proper load operation without flickering or voltage issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a power supply is added to the electronic switch, then the controller can be powered, but the voltage available to the load is reduced
Solution Approach 1:
The power supply charges the output capacitor during specific intervals (when the controllable conductor is non-conductive or during portions of AC cycles) before the load requires full power. This preliminary charging action stores energy in advance, allowing the load to receive full voltage when needed without continuous power supply intervention.
Solution Approach 2:
The power supply operates periodically rather than continuously, charging the output capacitor during specific time intervals (such as when the controllable conductor is non-conductive or during selected AC cycles). This periodic operation reduces the average voltage drop across the power supply while ensuring the load receives adequate power during active periods.
2Use of energy by stationary object
If the power supply draws current through the load to charge, then the power supply can be powered, but the load may illuminate or flicker inappropriately
Solution Approach 1:
The power supply charges the output capacitor during preliminary intervals when the controllable conductor is non-conductive, before the load is activated. This ensures the capacitor is pre-charged with sufficient energy to power the controller and other components without requiring current draw during load operation, thereby preventing inappropriate load illumination or flickering.
Solution Approach 2:
The output capacitor serves as an intermediary energy storage element between the power supply and the load. It decouples the charging operation from the load operation, allowing the power supply to charge during intervals when the load is not active, thus preventing direct current draw through the load during its operational periods.
3Ease of manufacture
If the electronic switch is designed as a two-wire device, then installation is simplified, but the power supply charging creates voltage drops
Solution Approach 1:
The power supply performs preliminary charging of the output capacitor during intervals when the controllable conductor is non-conductive, storing energy in advance. This allows the two-wire configuration to maintain full voltage delivery to the load during active operation, as the capacitor provides the necessary energy without requiring continuous power supply voltage drops.
Solution Approach 2:
The power supply operates periodically during specific AC cycles or intervals when the load is not active, charging the output capacitor in advance. This periodic charging strategy allows the two-wire electronic switch to maintain simple installation while ensuring full voltage is available to the load during operational periods.
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 control of AC power delivery to electrical loads, ensuring maximum intensity for lighting loads and preventing inappropriate operation, while minimizing voltage drop and flickering, thus addressing the limitations of traditional two-wire switches.
Implementation Method 1
an output capacitor operable to develop to the DC supply voltage for powering the controller
Implementation Method 2
an in-line power supply that controls when the output capacitor charges asynchronously with respect to the frequency of the AC power source
Data Source
AI summary
A two-wire smart load control device, such as an electronic switch, for controlling the power delivered from a power source to an electrical load comprises a relay for conducting a load current through the load and an in-line power supply coupled in series with the relay for generating a supply voltage across a capacitor when the relay is conductive. The power supply controls when the capacitor charges asynchronously with respect to the frequency of the source. The capacitor conducts the load current for at least a portion of a line cycle of the source when the relay is conductive. The load control device also comprises a bidirectional semiconductor switch, which is controlled to minimize the inrush current conducted through the relay. The bidirectional semiconductor switch is rendered conductive in response to an over-current condition in the capacitor of the power supply, and the relay is rendered non-conductive in response to an over-temperature condition in the power supply.