Dimming Circuit Signal Conversion for Stable Harmonic-Free Lighting
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Solution Overview
Problem
Thyristor phase control dimming methods generate harmonic pollution, harming lighting devices due to the output voltage's instability and high harmonic content.
Innovation Solution
A dimming circuit with a signal processing unit and controller that converts high-voltage dimming signals into stable low-voltage signals, using controllable switches and preprocessing circuits to ensure reliable dimming control without harming the lighting device, and includes multiple switching circuits for multiplex control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thyristor phase control dimming method is used, then dimming function is achieved, but harmonic pollution is generated harming the lighting device
Solution Approach 1:
The patent introduces an intermediary signal processing unit between the dimming signal source and the lighting device. This unit converts the harmful thyristor phase control signal into a harmless PWM signal, eliminating harmonic pollution while preserving dimming functionality. The intermediary acts as a buffer that transforms the signal form without losing the essential dimming control capability.
Solution Approach 2:
The patent changes the parameter form of the dimming signal from analog voltage control (0-10V) or phase-cut waveform to digital PWM pulse width modulation. This parameter transformation allows the same dimming effect to be achieved through a different signal mechanism that does not generate harmonic pollution, thus protecting the lighting device while maintaining dimming performance.
2Ease of operation
If thyristor phase control dimming is used, then dimming control is achieved, but output voltage stability deteriorates
Solution Approach 1:
The patent replaces the mechanical thyristor phase control system with an electronic PWM control system. Instead of using thyristors to chop the waveform and create unstable voltage, the system uses microcontroller-based PWM generation that provides precise, stable voltage control. This substitution eliminates the inherent instability of phase-cut dimming while maintaining ease of operation through digital control interfaces.
3Ease of operation
If high voltage dimming signal is processed directly, then dimming control is implemented, but circuit reliability decreases due to strong electricity
Solution Approach 1:
The patent introduces an intermediary signal processing unit that acts as an electrical buffer between the high-voltage dimming signal source and the low-voltage controller circuitry. This intermediary converts high-voltage signals to low-voltage PWM signals, protecting the controller from voltage spikes and electrical noise while maintaining full control capability. The intermediary isolates the sensitive electronics from harmful electrical conditions.
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 stabilizes the output voltage, preventing harmonic pollution and ensuring the reliability of the dimming circuit, thereby extending the service life of lighting devices and improving dimming control precision.
Implementation Method 1
a first controllable switch Q1... the to-be-processed dimming signal MltCon and the first voltage signal controlling turning-on and turning-off of the first controllable switch, the to-be-processed dimming signal MltCon being converted into a second voltage signal MltConIn
Implementation Method 2
a preprocessing circuit, connected to the second terminal of the first controllable switch, and configured to perform at least one of voltage regulation or filtering of the second voltage signal MltConIn
Implementation Method 3
perform at least one of voltage regulation or filtering of the second voltage signal MltConIn
Implementation Method 4
a first diode, configured to rectify the to-be-processed dimming signal MltCon
Data Source
AI summary
A dimming circuit and a lighting device includes a signal processing unit having a first controllable switch connected to a to-be-processed dimming signal, a first port of a controller, and a first voltage signal; the to-be-processed dimming signal and the first voltage signal controlling turning-on/off the first controllable switch, the to-be-processed dimming signal being converted into a second voltage signal, and outputted from the second terminal to the controller; and the controller, extracting a corresponding dimming control signal based on change of the second voltage signal, and outputting the dimming control signal to a to-be-dimmed terminal. This circuit converts a electrical signal implements dimming control in conjunction with the controller, and the controller only processes weak electrical signals, thereby guaranteeing the reliability of the output voltage of the dimming circuit, and preventing the output voltage of the dimming circuit from harming the to-be-dimmed terminal.