Dimmer Conduction Angle Detection Circuit Voltage Limiting
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Solution Overview
Problem
Existing dimmer conduction angle detection circuits, such as RC filters and microcontroller-based systems, are sensitive to fluctuations in line voltage amplitude, leading to undesired changes in light output at constant dimmer settings and lack sufficient linearity in lamp light output regulation.
Innovation Solution
A conduction angle detection circuit that includes a comparator, a limiting circuit, a threshold supply circuit, and a filter, which provides a voltage-limited dimmer reference level output proportional to the dimmer setting, unaffected by source voltage fluctuations, and is integrated into a ballast circuit to drive light sources with adjustable illumination levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an RC filter is used for conduction angle detection, then the circuit complexity is reduced, but the output becomes sensitive to line voltage fluctuations and lacks sufficient linearity
Solution Approach 1:
A voltage-limiting circuit is introduced as an intermediary component between the rectifier output and the RC filter. This mediator clamps the voltage to a maximum level, preventing line voltage fluctuations from propagating to the detection circuit, while allowing the RC filter to maintain its simplicity for conduction angle detection.
Solution Approach 2:
The circuit uses the rectified voltage signal itself as feedback to the voltage-limiting circuit. The limiting circuit continuously monitors the rectified voltage and adjusts its output to maintain a stable reference level regardless of input voltage variations, ensuring reliable detection without increasing overall system complexity.
2Measurement precision
If a microcontroller is used for conduction angle detection, then the linearity and precision are improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces the expensive and complex microcontroller with a simple, inexpensive analog circuit consisting of a voltage-limiting circuit and an RC filter. This disposable-like approach uses basic electronic components that are cheap and reliable, achieving sufficient precision without the overhead of a microcontroller system.
Solution Approach 2:
The patent substitutes the digital processing system (microcontroller) with an analog electronic system. The voltage-limiting circuit and RC filter continuously process the voltage signal in the analog domain, providing real-time conduction angle detection without the need for digital sampling, processing, and control algorithms.
3Device complexity
If the dimmer reference level output is directly taken from the rectifier, then the circuit simplicity is maintained, but the output is significantly affected by source voltage fluctuations
Solution Approach 1:
A voltage-limiting circuit is inserted as an intermediary between the rectifier and the output. This circuit clamps the voltage to a maximum reference level, creating a stable output that is independent of source voltage fluctuations while maintaining circuit simplicity.
Solution Approach 2:
The voltage-limiting circuit changes the voltage parameter of the signal by clamping it to a maximum level. This parameter transformation ensures that the output reference level remains stable regardless of variations in the input rectified voltage, achieving stability without complex circuitry.
Data Source
AI summary
A conduction angle detection circuit, and systems and methods incorporating the same, is disclosed. The circuit includes a comparator having a first input and a second input, and configured to provide a pulse-width modulated output in response to comparison of signals at the first input with signals at the second input. The output has a pulse width representative of a dimmer setting of a dimmer circuit. The circuit also includes a limiting circuit coupled to the comparator and configured to receive a rectified voltage and to provide a voltage-limited output in response to the rectified voltage to the first input of the comparator. The circuit also includes a threshold supply circuit configured to provide a threshold voltage to the second input of the comparator, and a filter coupled to the comparator. The filter is configured to convert the pulse-width modulated output of the comparator to the dimmer reference level signal.