HVAC Compressor Speed Control Using Discrete Thermostat Run Times
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Solution Overview
Problem
Existing HVAC systems face challenges in efficiently adapting to varying climate demands for cooling and heating, often requiring costly replacements and inefficient operation due to fixed speed compressors and thermostats, leading to increased energy consumption and noise.
Innovation Solution
The development of methods and apparatuses that allow for the use of discrete-speed thermostats to control variable-speed HVAC units, enabling the selection of multiple compressor speeds based on operational time and temperature thresholds, without the need for replacing existing thermostats or wiring, and adapting heat pumps for improved efficiency in climates with unequal cooling and heating demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-speed compressors are used to simplify the system, then device complexity is reduced, but energy consumption increases and operational efficiency decreases
Solution Approach 1:
The patent implements a multi-speed compressor control system that dynamically adjusts compressor speed based on cooling/heating demands. The controller selects from multiple discrete speeds (e.g., low, medium, high) rather than operating at a fixed single speed, allowing the system to optimize energy consumption while maintaining temperature setpoints across varying climate conditions.
2Use of energy by moving object
If variable-speed compressors are used to reduce energy consumption, then energy efficiency improves, but device complexity and installation cost increase
Solution Approach 1:
The patent designs a multi-speed compressor system that can operate across multiple discrete speeds using a standardized control architecture. This universal design allows the same hardware platform to serve both single-speed and multi-speed applications, reducing the complexity increment when upgrading to variable-speed operation while maintaining energy efficiency benefits.
Solution Approach 2:
The system changes the operational parameters of the compressor by implementing multiple discrete speed levels instead of a single fixed speed. The controller adjusts the compressor speed parameter based on temperature differentials, load conditions, and climate demands, thereby reducing energy consumption without requiring a complete system redesign.
3Ease of operation
If discrete-speed thermostats are used to control variable-speed units, then ease of operation and compatibility are improved, but temperature control precision may be reduced
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors temperature sensor readings and adjusts compressor speed accordingly. Even with discrete thermostat signals, the system uses feedback from temperature sensors to select appropriate compressor speeds, maintaining temperature control precision while preserving compatibility with simple discrete-speed thermostats.
Solution Approach 2:
The system uses temperature sensors positioned at multiple locations within the conditioned space to gather more temperature data than a single thermostat reading would provide. This partial redundancy allows the controller to make more precise speed selections, compensating for the limited resolution of discrete-speed thermostat signals.
Data Source
AI summary
Methods of controlling air conditioning and HVAC units using a thermostat for a discrete-speed unit that include changing speed based on how long the unit operates at a particular speed. Speed may be increased if a unit operates for longer than a predetermined time at a particular speed, and speed may be reduced if the unit operated for less than a specific amount of time during the prior run. In different embodiments, single-stage thermostats may control units that operate at three speeds, and two-stage thermostats may control units that operate at three to five or more speeds. In addition, in some embodiments, outdoor coil temperature may be measured and considered in determining speed. Further, in some embodiments, maintaining continuous or repeated operation at a boost speed may be avoided. Energy savings and noise reduction may result.