Universal Dimmer With Periodic Power Interruption
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Solution Overview
Problem
Phase-cut dimmers face limitations in achieving a wide dimming range due to high power consumption and incompatibility with varying load impedances, restricting their ability to operate efficiently across different power line systems and load conditions.
Innovation Solution
The design incorporates a low-power consumption DC power supply circuit and control circuit, along with a zero-crossing detector and timer synchronized with the AC supply, enabling adaptive dimming mode selection based on load impedance and using a Voltage-Fraction to Duty-Cycle Converter to generate a duty-cycle independent of timing factors, ensuring steady power supply and automatic mode switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the dimming range is extended to 0%-100%, then the adaptability is improved, but the power consumption increases because the AC switch must remain on continuously at 100% dimming, preventing power supply to the DC power supply circuit
Solution Approach 1:
The patent implements periodic action by forcing the AC switch to turn off during each AC cycle regardless of the dimming control signal, creating regular intervals where power can be supplied to the DC power supply circuit. This periodic switching ensures the controller maintains operational power while still providing dimming control across the full 0%-100% range.
Solution Approach 2:
The patent introduces an intermediary mechanism (the forced off-period during each AC cycle) that mediates between the conflicting requirements of continuous power supply to the load and periodic power supply to the controller. This intermediary time window allows both the load to receive power and the controller to be recharged without conflict.
2Loss of energy
If the power consumption of the DC power supply circuit is reduced, then the energy efficiency is improved, but the timing accuracy deteriorates due to insufficient power for stable operation of timing components
Solution Approach 1:
The timing circuit receives power periodically during the forced off-period of the AC switch, synchronizing its operation with the AC cycle. This periodic power supply ensures sufficient power is available during critical timing operations while minimizing overall power consumption during the dimmed periods when the switch is on.
Solution Approach 2:
The patent employs feedback mechanisms where the controller monitors the AC cycle timing and adjusts the forced off-period timing accordingly, ensuring the timing circuit receives power at the optimal moments within each cycle. This feedback loop maintains timing accuracy despite the reduced average power consumption.
3Use of energy by moving object
If the dimming control range is limited to 23%-88% duty-cycle, then the power consumption is reduced, but the adaptability deteriorates as the dimmer cannot achieve true 0%-100% dimming control
Solution Approach 1:
By implementing periodic forced off-periods synchronized with AC cycles, the system enables full 0%-100% dimming control capability. The periodic power interruption allows the controller to maintain operation while permitting the full range of dimming values, including the previously unavailable 0%-23% and 88%-100% ranges.
Data Source
AI summary
Disclosed is a phase-cut dimmer, comprising an AC switch coupled in series between an AC supply and a load; a DC power supply powered from a voltage across the switch; a zero-crossing detector of a phase-cut AC voltage across the switch; a timer generating a timing signal of a duty-cycle proportional to a variable fraction of a peak voltage of a sawtooth signal, wherein the sawtooth signal is synchronized to the zero-crossing detector; a blanking signal generator triggered by a duty-cycle detector to reduce the duty-cycle when the duty-cycle of the timing signal exceeds a predetermined maximum limit; and an operation mode selector activated by an output of an inductive load detector.