Compressor Motor Current Correction for Load Torque Synchronization
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Solution Overview
Problem
Conventional air-conditioning apparatuses experience out-of-synchronization issues with the motor when the load torque changes rapidly, leading to abnormal stops.
Innovation Solution
A motor control device with a load-torque detecting unit and a current correcting unit that increases the motor current in response to increased load torque, preventing out-of-synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If position-sensorless control is used to avoid installing a magnetic-flux sensor in high-temperature and high-pressure conditions, then the motor can operate without a sensor, but the motor is likely to go out of synchronization when load torque changes rapidly
Solution Approach 1:
The control device increases the current flowing through the motor in advance when an increase in load torque is detected, before the out-of-synchronization condition occurs. This preliminary action prevents the motor from going out of synchronization by proactively adjusting the current to match the increased load torque demand.
Solution Approach 2:
The control device continuously monitors the load torque of the motor and uses this feedback information to adjust the current flowing through the motor. When an increase in load torque is detected, the control device increases the current accordingly, creating a closed-loop control system that maintains synchronization stability.
2Device complexity
If the motor operates without direct magnetic-pole position detection, then the system is simpler, but the motor cannot respond quickly to rapid load torque changes
Solution Approach 1:
The invention replaces direct magnetic-pole position detection with load torque detection to determine motor state. By monitoring load torque changes rather than directly detecting magnetic-pole position, the system achieves responsive control with simpler sensing requirements, substituting one measurement approach for another that is more suitable for the application.
3Reliability
If the motor current is increased to handle higher load torque, then the motor can maintain synchronization, but the current may exceed safe operating limits
Solution Approach 1:
The control device dynamically adjusts the current flowing through the motor based on the detected load torque conditions. Rather than maintaining a fixed high current level, the system increases current only when and to the extent that load torque increases are detected, allowing the motor to handle variable load conditions while avoiding unnecessary overcurrent operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables continuous operation of the motor by adjusting the current flow in response to changing load torque, thereby preventing out-of-synchronization and abnormal stops.
Implementation Method 1
a load-torque detecting unit that detects load torque of the motor
Implementation Method 2
a current correcting unit that controls a current flowing through the motor in accordance with information detected by the load-torque detecting unit
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A motor control device 200 controlling a motor 30 includes a load-torque detecting unit 26 configured to detect load torque of the motor 30 and a current correcting unit 27 configured to control a current flowing through the motor 30 in accordance with information detected by the load-torque detecting unit 26. The current correcting unit 27 increases the current flowing through the motor 30 in accordance with an increase in the load torque detected by the load-torque detecting unit 26.