HVAC Compressor Speed Control for Non-Communicating Thermostats
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing HVAC systems face limitations in operation and performance when using non-communicating thermostats due to the lack of necessary signals for variable operation, restricting the control system's ability to adjust operating modes effectively.
Innovation Solution
Incorporation of additional control circuitry that enables the HVAC system to operate in various modes using signals from conventional, non-communicating thermostats by providing predetermined values as substitutes for missing data, allowing for enhanced control and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a non-communicating thermostat is used to control the HVAC system, then the thermostat cost and complexity are reduced, but the system operation flexibility and performance are limited
Solution Approach 1:
The control circuitry acts as an intermediary between the simple non-communicating thermostat and the complex vapor compression system. It receives basic thermostat signals and translates them into detailed control commands for the compressor, enabling variable speed operation without requiring a complex communicating thermostat. This mediator approach allows the system to achieve advanced functionality while maintaining compatibility with simple thermostats.
Solution Approach 2:
The control circuitry autonomously determines target evaporator temperatures and adjusts compressor speeds based on received thermostat signals without requiring additional input from the thermostat. The system self-generates the necessary control parameters and operates in different modes (first mode for communicating thermostats, second mode for non-communicating thermostats) based on the thermostat capabilities, enabling the simple thermostat to effectively control a sophisticated system.
2Productivity
If a communicating thermostat is used to provide detailed control signals, then the system performance and efficiency are improved, but the thermostat cost and complexity increase
Solution Approach 1:
The control circuitry serves as an intermediary that bridges the gap between simple thermostat signals and complex system requirements. It enhances basic thermostat commands by automatically determining target evaporator temperatures and generating appropriate compressor speed adjustments, thereby achieving high system efficiency without requiring a expensive communicating thermostat.
Solution Approach 2:
The control circuitry dynamically changes system parameters (compressor speed, target evaporator temperature) based on the type of thermostat connected and the received signals. It adapts its operation between first mode (for communicating thermostats) and second mode (for non-communicating thermostats), optimizing system performance for each scenario without requiring the thermostat itself to be complex.
3Use of energy by moving object
If the compressor speed is adjusted based on target evaporator temperature, then the system energy efficiency is improved, but the control system complexity increases
Solution Approach 1:
The control system implements feedback control by continuously monitoring the evaporator temperature and adjusting the compressor speed to maintain the target evaporator temperature. The control circuitry receives thermostat signals, determines target temperatures, compares them with actual conditions, and dynamically adjusts compressor operation accordingly. This feedback mechanism optimizes energy efficiency while keeping the control logic integrated within the existing control circuitry.
Solution Approach 2:
The system transitions from static compressor operation to dynamic variable speed control based on real-time temperature conditions. The control circuitry enables the compressor to operate at different speeds according to the target evaporator temperature and actual system state, optimizing energy consumption while adapting to changing load conditions without requiring a completely new control architecture.
Data Source
AI summary
A heating, ventilation, and/or air conditioning (HVAC) system includes a controller configured to receive data communications from a communicating thermostat and also configured to receive a demand signal from a non-communicating thermostat. When the controller is receiving the data communications from the communicating thermostat, the controller is configured to generate a compressor speed control signal based on the data communications from the communicating thermostat. The data communications are based on a difference between a thermostat temperature set point and a temperature measurement for a conditioned space. When the controller is receiving the demand signal from the non-communicating thermostat, the controller is configured to generate the compressor speed control signal based on a predefined coil temperature set point and a measured coil temperature. The demand signal is based on a non-communicating thermostat temperature set point not corresponding to the temperature measurement.