Permanent Magnet Compressor Startup Control for Demagnetization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Compressors experience performance degradation due to demagnetization of the rotor's permanent magnet, which is not detected and addressed in current control methods, leading to reduced control accuracy and inability to output maximum power.
Innovation Solution
A method for detecting demagnetization by applying a detection current with a q-axis component during startup, calculating flux linkage, and resetting operating parameters such as maximum output current and overcurrent protection points to adapt to the demagnetization level, ensuring optimal performance and preventing further demagnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the compressor operates with a permanent magnet rotor, then high power output and efficiency are achieved, but demagnetization occurs due to overcurrent or long-term storage, causing performance degradation
Solution Approach 1:
The patent applies preliminary action by performing demagnetization detection during the startup phase before the compressor enters normal operation. A detection current is applied to the motor windings, and the resulting current response is analyzed to determine the magnetic flux linkage of the permanent magnet. This early detection allows the system to identify demagnetization conditions before they cause significant performance degradation or damage, enabling preventive maintenance or parameter adjustment.
Solution Approach 2:
The patent implements feedback by continuously monitoring the motor's current response during startup and using this information to adjust operating parameters. The control system compares the measured current response against expected values to detect demagnetization, then provides feedback to reset operating parameters such as maximum output current limits and overcurrent protection points, ensuring the compressor operates safely within its actual capabilities.
2Productivity
If demagnetization is not detected and operating parameters are not reset, then the compressor continues operating under original control model, but control accuracy decreases and performance deteriorates
Solution Approach 1:
The system uses feedback from the detection current response to continuously assess the magnetic flux linkage and compare it against theoretical values. This feedback mechanism enables real-time detection of demagnetization and triggers automatic resetting of operating parameters, maintaining control accuracy despite the permanent magnet's degraded state.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting operating parameters based on the detected demagnetization level. When demagnetization is detected, the system resets parameters including maximum output current, overcurrent protection points, and control model constants. This ensures the control system adapts to the actual magnetic field strength, restoring and maintaining control accuracy.
3Loss of information
If detection current is applied with both d-axis and q-axis components, then comprehensive motor response is obtained, but parameter determination becomes more complex
Solution Approach 1:
The patent extracts only the necessary information for demagnetization detection by applying detection current with a simplified structure - using only a q-axis component with zero d-axis component. This extraction approach focuses the detection on the specific parameter needed (magnetic flux linkage) without the complexity of full two-axis excitation, reducing computational burden while maintaining detection effectiveness.
Solution Approach 2:
The system changes the detection approach by using a simplified current vector (q-axis only) instead of full d-q axis excitation. This parameter change in the detection strategy reduces the complexity of the detection algorithm and parameter determination while still providing sufficient information to calculate magnetic flux linkage and detect demagnetization accurately.
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
This approach effectively suppresses performance degradation by detecting and adapting to demagnetization, allowing the compressor to maintain maximum power output and prevent further damage.
Implementation Method 1
detecting whether there is demagnetization of the permanent magnet of the rotor or not according to a response of the motor to the applied detection current
Data Source
AI summary
A compressor and a control method thereof are provided. The compressor includes a motor with a rotor of a permanent magnet. According to embodiments, the method of controlling the compressor includes: applying a detection current to the motor in response to a command of starting the compressor; detecting whether there is demagnetization of the permanent magnet of the rotor according to a response of the motor to the applied detection current; resetting an operating parameter of the compressor if there is the demagnetization; and starting the compressor according to the reset operating parameters. According to embodiments of the present disclosure, when the compressor is to be started, demagnetization is detected first, and the operating parameter are set accordingly, so as to suppress or avoid performance degeneration due to the demagnetization.