Thermostat Power Buffering Without a Common Wire
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing thermostats face challenges in providing reliable power without a 'common' wire, requiring either a battery that needs frequent replacement or complex hardwiring, and struggle to integrate advanced functionalities like Wi-Fi connectivity and powerful processors while maintaining ease of DIY installation and aesthetic appeal.
Innovation Solution
A thermostat design that includes a power extraction circuit to harness electrical power from HVAC control wires, a rechargeable battery, and a power control circuit to manage power supply, allowing for efficient operation and charging during varying power demands, along with a compact and visually appealing interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If power stealing is used to power the thermostat without a common wire, then wiring complexity is reduced, but the thermostat cannot support advanced functionalities requiring higher power consumption
Solution Approach 1:
A rechargeable battery is introduced as an intermediary energy storage device between the power stealing circuit and the thermostat load. The battery accumulates energy during low-demand periods and supplies power during high-demand periods, enabling advanced functionalities while maintaining compatibility with two-wire installations without a common wire.
Solution Approach 2:
The system dynamically changes power delivery parameters by switching between power stealing mode and battery discharge mode based on real-time power availability and demand. The power control circuit adjusts current and voltage parameters to optimize energy utilization from the HVAC control wires while preventing overload.
2Adaptability or versatility
If a battery is used to provide operating power, then independence from common wire is achieved, but maintenance requirements increase due to frequent battery replacement
Solution Approach 1:
The rechargeable battery is automatically recharged through power stealing from the HVAC control wires during system OFF periods, eliminating the need for manual battery replacement. The system self-manages energy accumulation and discharge, providing continuous operation without user intervention for battery maintenance.
Solution Approach 2:
Energy is pre-stored in the rechargeable battery during periods when power demand is low (HVAC OFF periods), preparing the system in advance for high-power operations. This preliminary energy accumulation ensures that advanced functionalities can be activated without immediate power constraints.
3Ease of manufacture
If power is stolen during OFF periods, then the thermostat can operate without common wire, but the available power is limited and insufficient for advanced features
Solution Approach 1:
The rechargeable battery performs preliminary energy accumulation during HVAC OFF periods by storing electrical energy from power stealing. This pre-stored energy enables the thermostat to support power-intensive advanced functionalities such as Wi-Fi connectivity, high-resolution displays, and powerful processors that would be impossible with instantaneous power stealing alone.
4Adaptability or versatility
If voltage drop is used during ON periods, then power can be drawn without common wire, but the voltage drop may cause load coil dropout below response threshold
Solution Approach 1:
The rechargeable battery acts as an intermediary power source during HVAC ON periods, supplementing the voltage drop from power extraction. This ensures that the voltage remaining across the load coil stays above the dropout threshold, maintaining reliable HVAC control while enabling the thermostat to draw sufficient power for its operations.
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 reliable and efficient operation of advanced thermostats without a 'common' wire, supporting DIY installation, and providing robust, energy-efficient, and aesthetically pleasing solutions for HVAC system control.
Implementation Method 1
The power management circuit includes a power extraction circuit configured to extract electrical power from one or more of the plurality of received HVAC control wires
Implementation Method 2
A thermostat design that includes a power extraction circuit to harness electrical power from HVAC control wires, a rechargeable battery
Implementation Method 3
a power control circuit coupled to the power extraction circuit, the rechargeable battery, and the thermostat processing and control circuit
Data Source
AI summary
A thermostat includes a plurality of HVAC (heating, ventilation, and air conditioning) wire connectors for receiving a plurality of HVAC control wires corresponding to an HVAC system. The thermostat also includes a thermostat processing and control circuit configured to at least partially control the operation of the HVAC system and a powering circuit coupled to the HVAC wire connectors and configured to provide an electrical load power to the thermostat processing and control circuit. The powering circuit has a power extraction circuit configured to extract electrical power from one or more of the plurality of received HVAC control wires up to a first level of electrical power, a rechargeable battery, and a power control circuit. The power control circuit is configured to provide the electrical load power using power from the power extraction circuit and the rechargeable battery.