Thermostat Cycle Rate Control for Stable Room Temperature
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Solution Overview
Problem
Conventional room temperature control methods are inflexible and inefficient, failing to adapt to room characteristics and environmental changes, leading to large temperature swings and reduced energy efficiency due to limitations in span temperature resolution and thermal delays.
Innovation Solution
The system adjusts the total span around a setpoint temperature using a multiplicative factor and controls the duty cycle based on error and attenuation rates, allowing for dynamic cycle adjustments and mode selection based on environmental and room characteristics to maintain a constant temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed temperature span method is used for room temperature control, then the control logic is simple and easy to implement, but the temperature control accuracy deteriorates and large temperature swings occur
Solution Approach 1:
The patent applies dynamics by making the temperature span variable rather than fixed. The controller dynamically adjusts the temperature span based on the actual room temperature, thermal time delay characteristics, and heating/cooling unit status. This allows the control system to adapt to changing conditions and maintain accurate temperature control without excessive swings, resolving the contradiction between simple control logic and temperature control accuracy.
Solution Approach 2:
The patent changes the parameter of temperature span from a fixed value to a variable parameter that is continuously adjusted based on system state. By modifying the temperature span parameter dynamically according to thermal time delay and unit status, the system achieves both operational simplicity and improved temperature control accuracy, eliminating large temperature fluctuations.
2Ease of manufacture
If a fixed temperature span is used in electronic digital thermostat, then the hardware implementation is straightforward, but the temperature control precision deteriorates due to A/D converter resolution limits
Solution Approach 1:
The patent overcomes the fixed resolution limitation of A/D converters by dynamically changing the temperature span parameter. Instead of relying on fixed hardware resolution, the system adjusts the effective temperature measurement range based on actual conditions, thereby achieving higher precision temperature control without requiring more complex hardware.
Solution Approach 2:
The system introduces dynamic adjustment of the temperature span to compensate for the static resolution limits of the A/D converter. By making the temperature span adaptive rather than fixed, the system achieves precision beyond what the fixed hardware resolution would normally allow, while keeping the hardware implementation straightforward.
3Stability of the object's composition
If the heating or cooling unit operates with thermal time delays, then the system response is smooth, but the temperature control accuracy deteriorates and the setpoint temperature is not achievable
Solution Approach 1:
The patent applies preliminary action by anticipating the thermal time delay effect and adjusting the temperature span in advance. The controller predicts the temperature change based on the thermal time delay characteristic and proactively modifies the temperature span before the actual temperature deviation occurs. This allows the system to maintain accurate temperature control despite the inherent thermal delays, achieving both smooth response and setpoint accuracy.
Solution Approach 2:
The system uses feedback from the actual temperature measurement and thermal time delay characteristics to continuously adjust the temperature span. By monitoring the system state and adapting the temperature span accordingly, the controller compensates for thermal delays and maintains accurate temperature control, resolving the contradiction between smooth response and setpoint accuracy.
4Measurement precision
If the temperature span is reduced to improve temperature control accuracy, then the temperature control precision improves, but the cycle time increases and energy efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the temperature span adaptive rather than fixed. The controller dynamically adjusts the temperature span based on thermal time delay characteristics and heating/cooling unit status. This allows the system to maintain small temperature spans for high precision control when needed, while avoiding excessive cycling by considering the thermal response time, thereby achieving both temperature precision and energy efficiency simultaneously.
Solution Approach 2:
The patent changes the temperature span parameter dynamically based on system conditions. By adjusting the temperature span according to thermal time delay and unit status, the system achieves high temperature control precision without incurring the energy efficiency penalties that would result from constantly small temperature spans. The parameter adaptation allows the system to optimize both precision and efficiency.
Data Source
AI summary
The present invention controls a room temperature by controlling an environmental control unit. A total span about a setpoint temperature is adjusted in accordance with a previous total span and a multiplicative factor. The multiplicative factor is periodically updated from a desired cycle time and a previous cycle time. The room temperature may also be controlled by adjusting a duty cycle for controlling an environmental control unit. The duty cycle is adjusted based on an error associated with a previous control cycle and an attenuation factor. A new control cycle may be started by cutting the previous control cycle or a current control cycle may be extended if a predetermined condition is detected. The control mode is selected based on environmental characteristics and room characteristics. The control mode may include a span control mode and a duty cycle control mode that is selected from the cycle rate.