HVAC system, a method for operating the HVAC system and a HVAC controller configured for the same
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Solution Overview
Problem
Conventional HVAC systems require users to manually switch between heating and cooling modes, leading to frustration and inefficiency, especially in climates with rapid outdoor temperature changes, and often result in oscillations between modes during light load conditions.
Innovation Solution
An HVAC system that allows users to select a single comfort temperature, using a dynamic operating band and modified Proportional Integral (PI) error calculation to determine when to initiate heating or cooling, reducing unnecessary mode transitions and energy waste by considering occupancy and outdoor weather.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional HVAC systems use separate heating and cooling set points with manual mode switching, then users can control temperature, but user convenience deteriorates and mode oscillations occur during rapid temperature changes
Solution Approach 1:
The patent combines separate heating and cooling set points into a single comfort temperature set point. The controller maintains this single set point for both heating and cooling modes, eliminating the need for users to manually switch between modes or remember different set points. The system automatically determines whether heating or cooling is needed based on the relationship between indoor temperature and the single comfort set point.
Solution Approach 2:
The patent implements a dynamic operating band around the comfort temperature set point that adjusts based on outdoor temperature conditions. When outdoor temperature is significantly different from indoor comfort temperature, the operating band widens to prevent unnecessary mode switching. This dynamic adjustment reduces mode oscillations during rapid temperature changes while maintaining comfort within the adjustable band.
2Device complexity
If HVAC systems use fixed set points for heating and cooling modes, then temperature control is simple, but energy efficiency deteriorates due to unnecessary mode transitions
Solution Approach 1:
The operating band dynamically adjusts its width based on outdoor temperature conditions. When outdoor temperature is extreme (very hot or very cold), the band widens to prevent the system from switching to the opposite mode unnecessarily. For example, when outdoor temperature is below a lower threshold, the cooling mode operating band extends to lower temperatures, preventing premature cooling activation. This reduces energy waste from unnecessary mode transitions while maintaining comfort.
Solution Approach 2:
The system changes the operating parameters (operating band width) based on outdoor temperature conditions. The controller adjusts the effective set point range dynamically rather than using fixed set points, allowing the system to adapt to external conditions and avoid energy-wasting mode oscillations.
3Measurement precision
If HVAC systems rapidly switch between heating and cooling modes to maintain comfort temperature, then temperature control precision improves, but system reliability deteriorates due to excessive mode oscillations
Solution Approach 1:
The operating band dynamically adjusts based on outdoor temperature conditions to balance precision and stability. When outdoor conditions are extreme, the band widens to prevent oscillations. When outdoor conditions are moderate, the band narrows to maintain tighter temperature control precision. This dynamic adjustment resolves the contradiction between precision and stability.
Solution Approach 2:
The dynamic operating band acts as an intermediary buffer between the comfort temperature set point and the actual mode switching decisions. Rather than switching modes exactly at the set point, the band provides a transition zone that smooths out rapid switching while still maintaining temperature control within an acceptable range.
4Ease of operation
If HVAC systems use a single comfort temperature set point for both heating and cooling, then user convenience improves, but determining when to initiate opposite modes becomes more complex
Solution Approach 1:
The controller dynamically adjusts the operating band width based on outdoor temperature conditions. This dynamic parameter allows the system to maintain a single comfort set point for user convenience while the controller logic remains manageable through standardized algorithms that adjust the effective control range based on external conditions.
Solution Approach 2:
The system pre-determines threshold temperatures for mode transitions based on the comfort set point and outdoor conditions. Rather than complex real-time calculations, the controller uses pre-established threshold logic to determine when to switch modes, simplifying the control implementation while maintaining the benefits of a single set point.
Data Source
AI summary
In some embodiments, a controller for a heating, ventilating and air conditioning (HVAC) system comprises an interface and a processor. The interface receives a comfort temperature set point and a sensed temperature for the enclosed space. The comfort temperature set point comprises a single set point used for both heating and cooling mode operation of the HVAC system. The processor determines a total error value based on comparing the sensed temperature and comfort temperature set point, selects a mode of operation based on the total error value, and operates the HVAC system in the selected mode of operation.