Dimmable Driver TRIAC Simulation Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mains dimmers with TRIACs struggle to properly operate energy-saving lamps, leading to issues like non-starting, flickering, and humming due to low power consumption and erratic behavior when dimming, as they require a minimum output current that energy-saving lamps often fail to meet.
Innovation Solution
An electronic driver that generates duty cycle controlled current and couples an auxiliary impedance to the mains during periods when the lamp current is off to maintain the TRIAC's requirements, ensuring a minimum current is drawn from the dimmer, and generates high-frequency current when the mains voltage is zero to satisfy the TRIAC's needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an energy-saving lamp with electronic driver is connected to a mains dimmer with TRIAC, then the lamp can be dimmed, but the TRIAC cannot maintain proper operation due to insufficient current, causing non-starting, flickering, and humming
Solution Approach 1:
The patent introduces a TRIAC simulation circuit as an intermediary component that actively generates a current waveform mimicking the characteristics of an incandescent lamp load. This simulated current satisfies the TRIAC's minimum hold current and latching current requirements, enabling stable operation when driving energy-saving lamps through dimmers. The circuit includes a current source, shaping network, and control logic that work together to create the necessary current profile during critical TRIAC switching moments.
Solution Approach 2:
The patent dynamically adjusts current parameters (magnitude, waveform shape, timing) based on the operating conditions. The TRIAC simulation circuit monitors the actual lamp current and modifies its output current characteristics to maintain TRIAC operation within safe parameters. This includes adjusting the current amplitude to exceed minimum thresholds and shaping the waveform to provide adequate current during the critical conduction angle periods.
2Illumination intensity
If the lamp current is reduced for dimming, then the light intensity decreases, but the TRIAC requires a minimum current to remain latched, creating a conflict
Solution Approach 1:
The patent separates the lamp driving function from the TRIAC current support function. The driver circuit independently controls the actual lamp current for dimming while simultaneously operating a separate TRIAC simulation current source. This segmentation allows the lamp current to be reduced for dimming purposes while the simulation current maintains the TRIAC latching requirement, resolving the conflict between light intensity control and power maintenance.
Solution Approach 2:
The TRIAC simulation circuit generates periodic current pulses synchronized with the mains frequency and TRIAC conduction periods. These periodic current injections occur at critical moments in the AC cycle to ensure the TRIAC remains latched, while allowing the actual lamp current to vary for dimming control. The periodic nature ensures reliable TRIAC operation throughout the dimming range.
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
A driver (100; 200) for driving a dimmable load (L) is powered from phase- cut mains (U1) and determines the dimming state of the load on the basis of the phase of the cutting of the mains. The driver comprises: a load current generating device (130; 230) generating load current; a controllable auxiliary load (170; 270) connected to an input (131; 231) of the load current generating device; a control device (140; 240) controlling the auxiliary load. The control device has an input (141; 241) receiving a signal indicating the momentary voltage at the driver input. The load current generating device generates interrupted current pulses, so that the average output current corresponds to the dim command reflected by the phase cutting angle of the input mains. The control device switches the auxiliary load on during those time periods when the output current generated by the load current generating device is zero.