Transformer Bleed Coil for TRIAC Dimming Stability
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Solution Overview
Problem
Traditional TRIAC dimmers struggle to maintain a sustainable hold-up current for solid-state lamps during deep dimming conditions, leading to limited load applications and dimming performance due to the low power operation of these lamps.
Innovation Solution
A system incorporating a transformer and a switch that bleeds a portion of the current to a ground reference based on the dimming level, ensuring a consistent current supply to solid-state light emitting diodes, which includes a transformer with coils and a switch connected in series with resistance and capacitance to manage current levels effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a traditional TRIAC dimmer is used for solid-state lamps, then the lamp can operate at low power levels, but the TRIAC cannot maintain the hold-up current and shuts OFF during deep dimming conditions
Solution Approach 1:
A bleed coil is introduced as an intermediary component connected to the secondary winding of the transformer. This bleed coil provides an alternative current path that reflects current back to the primary side, effectively mediating between the low current demand of the LED and the minimum hold-up current requirement of the TRIAC, thereby maintaining TRIAC conduction stability during deep dimming conditions
2Illumination intensity
If the dimming level is reduced to achieve deep dimming, then the luminous intensity decreases, but the current through the TRIAC drops below the hold-up current level
Solution Approach 1:
The bleed coil operates in conjunction with the AC cycle to provide periodic current reflection. During each half-cycle, the bleed coil draws current from the secondary winding, which reflects back to the primary side as a hold-up current component, ensuring the TRIAC receives sufficient current periodically to maintain conduction even when the LED load current is minimal
3Reliability
If a bleed coil is added to maintain hold-up current, then the TRIAC remains stable during deep dimming, but the device complexity increases
Solution Approach 1:
The bleed coil is designed to serve multiple functions: it provides the hold-up current reflection to maintain TRIAC conduction, and it can also function as part of the dimming control circuitry. By integrating these functions into a single component, the patent reduces the overall device complexity despite adding functionality to maintain reliability during deep dimming
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 system effectively maintains the TRIAC in an ON state during deep dimming conditions, preventing it from shutting off and ensuring stable illumination, thereby enhancing the operating efficiency and dimming performance for solid-state lamps.
Implementation Method 1
The transformer includes a coil. The transformer is configured to receive a first current. The coil is configured to, based on the first current, output a second current to power the solid-state light emitting diode.
Implementation Method 2
The switch is configured to, based on the dimming level that corresponds to the amount of light provided from the solid-state light emitting diode, bleed a portion of the second current out of the coil to a ground reference in order to divert the portion of the second current from being supplied to the solid-state light emitting diode.
Data Source
AI summary
A system configured to provide current to power a solid-state light emitting diode in accordance with a dimming level, wherein the dimming level corresponds to an amount of light provided from the solid-state light emitting diode. The system includes a transformer and a switch. The transformer includes a coil. The transformer is configured to receive a first current. The coil is configured to, based on the first current, output a second current to power the solid-state light emitting diode. The switch is configured to, based on a dimming level that corresponds to the amount of light provided from the solid-state light emitting diode of the system, bleed a portion of the second current out of the coil to a ground reference in order to divert the portion of the second current from being supplied to the solid-state light emitting diode.