Compressor Inverter Control from Thermostat ON/OFF Signal Timing
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Solution Overview
Problem
Air conditioners in North America with thermostats cannot precisely control indoor temperature using an inverter due to ON/OFF signal limitations, resulting in inferior energy conservation and comfort compared to Japanese models.
Innovation Solution
An operation controller for the compressor that uses an inverter to control the compressor based on the duration of the ON signal or the duration of the OFF state, estimating the load required for air-conditioning and adjusting the compressor's operation capacity accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a thermostat with ON/OFF control signal is used, then the device complexity is reduced and cost is lowered, but the temperature control precision deteriorates
Solution Approach 1:
The patent introduces an operation controller as an intermediary device that receives the simple ON/OFF signal from the thermostat and translates it into sophisticated inverter control signals. This intermediary converts the binary control signal into variable frequency commands, enabling precise temperature control while maintaining the simplicity of the original thermostat interface.
Solution Approach 2:
The control system is segmented into two functional parts: the simple thermostat that provides ON/OFF signaling, and the sophisticated operation controller that handles inverter control. This segmentation allows each component to specialize in its strength while the system as a whole achieves both simplicity and precision.
2Use of energy by moving object
If inverter control is implemented, then the energy conservation improves and comfort increases, but the device complexity increases
Solution Approach 1:
The operation controller autonomously analyzes the ON signal duration patterns and self-determines the appropriate inverter control parameters without requiring additional temperature sensors or complex user input. The system serves itself by converting simple presence/absence signals into sophisticated energy-saving control decisions.
Solution Approach 2:
The system changes the control parameter from simple ON/OFF binary states to variable frequency and duration parameters. By analyzing how long the ON signal persists, the system adjusts the inverter output frequency and compressor runtime, achieving energy optimization through parameter transformation rather than additional hardware.
3Ease of operation
If only ON signal is available without temperature data, then the ease of operation is maintained, but the control precision deteriorates
Solution Approach 1:
The system performs preliminary analysis of the ON signal characteristics before executing control decisions. By measuring the duration and pattern of ON signals in advance, the operation controller pre-determines the appropriate compressor capacity and runtime, enabling accurate load estimation without real-time temperature data.
Solution Approach 2:
The system uses the duration of ON signals as a feedback mechanism to infer load conditions. Longer ON signal durations indicate higher cooling/heating demands, while shorter durations suggest lower demands. This feedback loop allows the controller to continuously adjust compressor operation based on inferred load conditions.
Data Source
AI summary
The present invention provides a configuration in which a compressor can be controlled using an inverter in an air conditioner where only a signal related to ON/OFF of the compressor is output from a control terminal. An operation controller for a compressor is configured so that the compressor can be controlled using an inverter based on an ON signal output from a control interface of an air conditioner. Specifically, a target value of at least one of an outlet air temperature, an evaporation temperature and a condensation temperature, and a suction pressure and a discharge pressure of the compressor is corrected according to a duration of the ON signal or a duration of the OFF state thereof, thereby controlling the frequency of the compressor.