Dimmer Conduction Angle Detection Circuit Linearity
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Solution Overview
Problem
Existing conduction angle detection circuits for dimmer settings in ballast circuits are sensitive to fluctuations in line voltage amplitude, leading to undesired changes in light output and lack sufficient linearity, with simple RC filters being inadequate and microcontroller-based solutions being complex and costly.
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, minimizing the impact of line voltage fluctuations and ensuring linearity, without the need for a microcontroller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple 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:
The patent introduces a comparator as an intermediary component between the RC filter and the power conversion circuit. The comparator compares the filtered voltage against a reference voltage and generates a pulse-width modulated signal that accurately represents the dimmer setting. This intermediary element isolates the detection circuit from line voltage fluctuations while maintaining simplicity.
Solution Approach 2:
The patent transforms the analog filtered voltage signal into a pulse-width modulated digital signal through the comparator. This parameter change from continuous analog to discrete pulse-width representation improves linearity and immunity to voltage fluctuations while keeping the overall circuit simple.
2Measurement precision
If a microcontroller is used for conduction angle detection, then the linearity and stability of light output regulation is improved, but the device complexity and cost increase
Solution Approach 1:
The patent extracts only the essential function needed for dimmer detection from a full microcontroller system. By using a simple comparator circuit to generate a pulse-width modulated signal, the patent achieves accurate dimmer setting detection without the unnecessary complexity of a complete microcontroller, thereby reducing cost and complexity while maintaining precision.
Solution Approach 2:
The patent replaces the expensive and complex microcontroller with a simple, inexpensive comparator circuit. This substitution achieves the required measurement precision through a much simpler and more cost-effective means, suitable for mass production in lighting applications.
3Ease of manufacture
If the ballast circuit uses a conventional detection method, then the implementation is straightforward, but the light output changes with line voltage fluctuations at constant dimmer setting
Solution Approach 1:
The patent implements a feedback mechanism where the comparator continuously compares the filtered rectified voltage against a stable reference voltage. This feedback loop ensures that the pulse-width modulated output accurately reflects only the dimmer setting changes, not line voltage fluctuations, thereby maintaining light output stability while keeping the implementation straightforward.
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 provides a stable and linear dimmer reference level output that is not significantly affected by source voltage variations, achieving consistent lamp light output regulation across varying dimmer settings, and is cost-effective by eliminating the need for complex microcontroller-based systems.
Implementation Method 1
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
Implementation Method 2
a limiting circuit coupled to the comparator and configured to receive the rectified voltage and provide a voltage-limited output in response to the rectified voltage to the first input of the comparator
Implementation Method 3
a filter coupled to the comparator, the filter being configured to convert the pulse-width modulated output of the comparator to the dimmer reference level signal
Data Source
Figure 1~2
Figure 3~4
Figure 5A~6B
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.