Bidirectional Phase Cut Modulation for AC Lighting Control
Solution Overview
Problem
Conventional dimmer switches for AC lighting systems are limited in their ability to efficiently control and communicate with multiple lighting units using existing installed wiring infrastructure, particularly in terms of bidirectional communication and addressing individual or groups of units.
Innovation Solution
A system utilizing a controller and line units that employ phase cut modulation for communication, allowing bidirectional communication over AC power conductors, where the controller sends commands with addresses to specific line units, enabling individual or group control, and uses load modulation for reporting back information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If conventional dimmer switches use bidirectional AC switches (TRIAC) to control lighting, then lighting control functionality is achieved, but bidirectional communication capability is lost
Solution Approach 1:
The patent segments the control signal into distinct phases within each AC cycle: phase-cut portions carry control commands from controller to line units, while non-phase-cut portions allow line units to report status back to the controller. This temporal segmentation enables bidirectional communication over the same conductor without interference.
Solution Approach 2:
The system uses periodic AC power cycles as the communication medium, with each half-cycle containing encoded information. The controller modulates the phase angle at which it reconnects the TRIAC during each cycle to encode control commands, while line units use the same periodic structure to report back their status during designated time windows.
2Loss of information
If phase cut modulation is used for communication over AC power conductors, then bidirectional communication is enabled, but power delivery to lighting units is interrupted
Solution Approach 1:
The system employs periodic phase-cut modulation synchronized with the AC power frequency (50/60 Hz). Control commands are transmitted during brief phase-cut intervals that constitute a small fraction of each complete AC cycle, allowing uninterrupted power delivery during the remaining non-phase-cut portions of the cycle.
Solution Approach 2:
The system dynamically adjusts the phase angle at which the TRIAC is reconnected during each AC cycle based on the communication needs. The phase-cut duration and timing are variable, allowing the system to optimize between communication bandwidth and power delivery requirements in real-time.
3Ease of manufacture
If multiple line units are controlled through a single controller using existing wiring, then wiring infrastructure is preserved, but addressing and individual control of units becomes complex
Solution Approach 1:
The system implements feedback mechanisms where line units report their addresses, status, and operational parameters back to the controller during designated time windows in the AC cycle. This feedback enables the controller to maintain an updated registry of all connected units and their capabilities, simplifying subsequent individual or group addressing.
Solution Approach 2:
The patent creates a universal addressing scheme where all line units respond to standardized command formats with address fields. The controller can address individual units, groups of units, or all units using the same communication protocol, providing multi-functionality without requiring different wiring or control mechanisms for different addressing scenarios.
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
Enables efficient control and communication with multiple lighting units over existing AC power conductors, allowing for separate control of different groups of units and reporting back information, enhancing the functionality of the lighting system without the need for extensive wiring modifications.
Implementation Method 1
The controller uses phase cut modulation to communicate information (for example, lighting control commands) to the line units
Implementation Method 2
the line units receive the AC power signal, demodulate and recover the phase cut modulated information, and optionally communicate information back to the controller using load modulation
Data Source
AI summary
A system includes a controller and line units. The controller receives AC power from a power source and supplies an AC power signal via two conductors to the units. In one example, the controller is a dimmer switch and the units are intelligent LED lamps. The controller uses phase cut modulation to communicate information (for example, lighting control commands) to the units. The units receive the AC power signal, demodulate and recover the phase cut modulated information, and optionally communicate information back to the controller using load modulation. An addressed unit changes loading on the two conductors from phase cut time to phase cut time, thereby modulating information onto the AC power signal. The controller monitors the AC power signal, and demodulates and recovers the information. The overall bidirectional communication is referred to as bidirectional phase cut modulation over AC power conductors. Units can be controlled individually or in groups.