Phase-Controlled Dimmer for Stable Low-Loss Load Compatibility
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Solution Overview
Problem
Existing dimmers are limited in their compatibility with various types of loads and often fail to maintain a stable power supply to the control circuit, leading to inefficiencies and errors in light output control.
Innovation Solution
A dimmer design featuring a bidirectional switch, phase detector, power supply, and controller that modulates the bidirectional switch based on detected AC voltage phases and dimming levels, ensuring the bidirectional switch is in specific states during different periods of the AC voltage cycle to control light output effectively, while also maintaining a stable power supply through capacitive storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional dimmer design is used, then the control circuit can be simplified, but the compatibility with various types of loads is limited
Solution Approach 1:
The patent employs a bidirectional switch that dynamically changes its conduction state based on the detected phase of AC voltage. The switch transitions between conducting and non-conducting states at specific phase points, enabling the dimmer to adapt to different load types (incandescent, fluorescent, LED) by adjusting the timing and duration of power delivery to match the electrical characteristics of each load type.
Solution Approach 2:
The control circuit modifies multiple parameters including the conduction angle, switching frequency, and power delivery timing based on the detected AC voltage phase. By changing these parameters dynamically, the dimmer achieves broad load compatibility without requiring complex dedicated circuits for each load type, as the same circuit adapts its behavior to match the electrical requirements of different load categories.
2Illumination intensity
If phase control is implemented to adjust light output, then light dimming is achieved, but the power supply to the control circuit becomes unstable
Solution Approach 1:
The control circuit is designed to receive and store power from the AC source before the phase-controlled power delivery to the load begins. By preliminarily charging energy storage elements during the non-dimming portion of the AC cycle, the control circuit maintains stable operation even when the load receives reduced power during dimming, ensuring reliable control functionality throughout the dimming range.
Solution Approach 2:
The dimmer operates by periodically switching the bidirectional switch on and off during each AC voltage cycle. This periodic action creates distinct time windows where power is delivered to the control circuit versus the load, allowing the control circuit to receive regular power updates that maintain stability while still enabling continuous light output adjustment through varying the duty cycle of these periodic cycles.
3Power
If the bidirectional switch conducts throughout the entire AC cycle, then maximum power is delivered to the load, but conduction losses increase
Solution Approach 1:
The bidirectional switch operates in periodic cycles, conducting only during specific portions of each AC voltage cycle rather than continuously. By switching the bidirectional switch on during periods when AC voltage is high and off during low-voltage periods, the system delivers near-maximum power during conduction intervals while minimizing total conduction time, thereby reducing cumulative conduction losses while maintaining high average power delivery to the load.
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
This design enhances compatibility with a broader range of loads, reduces conduction losses, and minimizes errors in light output control, ensuring stable operation and reduced distortion of the current waveform.
Implementation Method 1
The power supply has a capacitive device configured to store the control power
Implementation Method 2
The controller is configured to, during the first and fourth time periods, modulate the bidirectional switch out of conduction to interrupt supply of electric power to the load
Data Source
AI summary
A bidirectional switch switched to conduct and interrupt a bidirectional current between a pair of input terminals. An input device receives a dimming level representing a value of light output of the load. A controller controls the bidirectional switch according to the dimming level. The controller controls the bidirectional switch to keep the bidirectional switch in an off-state from a start point of a half cycle of the AC voltage of the AC power supply to a first time point when a first time period therefrom elapses, and to turn the bidirectional switch to an on-state at the first time point. The controller turns the bidirectional switch to the off-state at a second time point when a second time period elapses from the first time point. The controller keeps the bidirectional switch in the off-state from the second time point to an end point of the half cycle.