Auxiliary Switch Circuit for Full-Wave Thermostat Signal Multiplexing
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Solution Overview
Problem
Older thermostats using half-wave rectification limit power consumption and efficiency when trying to connect three-wire systems over two wires, as they require a ground wire adapter that restricts full-wave rectification for HVAC control signal multiplexing.
Innovation Solution
An auxiliary switch with an adapter network and controller that allows full-wave rectification in thermostats by de-multiplexing control information from a common ground line using voltage differences across the adapter network, ensuring a stable ground reference and efficient communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a thermostat uses full-wave rectification for power, then power consumption efficiency is improved, but the ability to multiplex control signals on the ground line is lost
Solution Approach 1:
The patent segments the AC signal cycle into distinct phases (positive half-cycle and negative half-cycle) and assigns different functions to each phase. During the positive half-cycle, the thermostat performs full-wave rectification for efficient power consumption. During the negative half-cycle, the thermostat multiplexes control signals onto the ground line. This temporal segmentation allows both full-wave rectification and signal multiplexing to coexist without interference.
2Adaptability or versatility
If a ground wire adapter is used to enable two-wire connection, then installation flexibility is improved, but the thermostat is restricted to half-wave rectification
Solution Approach 1:
The patent implements dynamic switching of the thermostat's operational mode based on the AC signal phase. The thermostat dynamically transitions between power consumption mode (full-wave rectification during positive half-cycle) and signal transmission mode (multiplexing during negative half-cycle). This dynamic operation eliminates the need for ground wire adapters while maintaining both installation flexibility and power efficiency.
3Adaptability or versatility
If control signals are multiplexed on the ground line during full-wave rectification, then signal communication capability is improved, but ground reference stability deteriorates
Solution Approach 1:
The patent employs periodic action by confining signal multiplexing to specific time intervals (negative half-cycles) rather than continuous operation. This periodic signal injection occurs only when it does not interfere with the ground reference stability during the positive half-cycle when full-wave rectification is performing. The rhythmic, periodic nature of this approach ensures both communication capability and ground reference stability are maintained.
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 communication of control signals on a ground line during full-wave rectification, allowing for stable operation and increased power consumption without compromising the ground reference, thus overcoming the limitations of half-wave rectification.
Implementation Method 1
The adapter network providing a maximum and minimum voltage drop between the auxiliary switch ground reference and the thermostat ground reference to provide a stable reference at an expected maximum current flow
Implementation Method 2
Thermostats requiring power are increasingly used to control heating, ventilation and air conditioning (HVAC) equipment. These thermostats may be powered by a battery or from an externally supplied alternating current (AC) source.
Data Source
AI summary
An auxiliary switch is provided that allows a thermostat to use full wave rectification for power while still communicating control information to the auxiliary switch over a multiplexed ground-control line to control associated equipment.