Electric compressor control device, electric compressor, and electric compressor control method
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Solution Overview
Problem
Existing refrigerant system monitoring technologies, such as those described in PTL 1, are complex due to reliance on temperature detection, which complicates the estimation process.
Innovation Solution
An electric compressor control device that utilizes a control unit, physical quantity calculation, rotation speed acquisition, and refrigerant abnormality determination to simplify the configuration by comparing calculated physical quantities with threshold values based on motor rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature detection values from the refrigerant system are used to estimate system state, then estimation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts the temperature detection requirement from the system by determining that temperature sensors in the refrigerant system are not necessary. Instead, the control device uses only electrical parameters (current, voltage, frequency) already available from the inverter to calculate physical quantities and determine refrigerant abnormalities, thereby simplifying the device configuration while maintaining estimation capability
Solution Approach 2:
The patent enables the inverter's existing electrical parameter detection system to serve dual purposes: both motor control and refrigerant system monitoring. By calculating physical quantities from electrical parameters alone, the system makes the existing detection infrastructure work for multiple functions, eliminating the need for additional temperature sensors
2Measurement precision
If multiple detection values from the refrigerant system are used, then determination accuracy is improved, but ease of operation deteriorates
Solution Approach 1:
The patent makes the electrical parameter detection system universal by having it perform both motor control functions and refrigerant abnormality detection. The same current and voltage detection values used for inverter control are also utilized to calculate physical quantities and determine refrigerant system state, eliminating the need for separate detection systems
Solution Approach 2:
The patent changes the parameters used for abnormality determination from temperature-based parameters to electrical parameter-based parameters. By calculating physical quantities (such as power consumption, current density, or torque) from electrical parameters and comparing them against threshold values, the system achieves accurate determination while simplifying operation
Data Source
AI summary
This electric compressor control device comprises: a control unit of an inverter which controls a motor that drives a compressor; a physical quantity calculation unit which calculates, on the basis of one or a plurality of predetermined detection values acquired from the inverter, a physical quantity that varies depending on a workload of the compressor; a number-of-revolutions acquisition unit which acquires the number of revolutions of the motor; a storage unit which stores information representing a first threshold that varies depending on the number of revolutions of the motor, and defines whether or not the physical quantity is a normal value; and a refrigerant abnormality determination unit which determines whether or not there is an abnormality in a refrigerant system by comparing the calculated physical quantity with the first threshold, depending on the acquired number of revolutions.