Permanent Magnet Temperature Prediction for Motor Iron Loss Reduction
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Solution Overview
Problem
Existing motor systems face challenges in preventing irreversible demagnetization of permanent magnets due to temperature increases, as direct temperature monitoring of the permanent magnet is difficult, and the temperature trends of stator coils and permanent magnets differ, making it hard to accurately prevent demagnetization.
Innovation Solution
An iron loss reduction control apparatus and method that predicts the temperature of the permanent magnet based on the motor's driving state, adjusting the switching frequency of the inverter and current command to prevent overheating, using a permanent magnet temperature prediction unit, a first iron loss reduction unit, and a second iron loss reduction unit to manage heat transfer and reduce iron losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is attached to the permanent magnet to monitor its temperature in real time, then the temperature monitoring accuracy is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent uses the stator coil temperature as an intermediary parameter to indirectly monitor the permanent magnet temperature. Since direct measurement is complex, the system measures the stator coil temperature (which is easier to access) and uses it as a proxy to infer the permanent magnet temperature state, thereby avoiding the need for direct temperature sensors on the permanent magnet while still achieving effective temperature monitoring and protection
2Device complexity
If the stator coil temperature is used to represent the permanent magnet temperature, then the device complexity is reduced, but the temperature measurement accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the stator coil temperature measurement is continuously fed back to the control system. The control system uses this feedback information to adjust motor operating parameters (such as reducing power output or adjusting current) when the stator coil temperature exceeds predetermined thresholds, thereby indirectly controlling the permanent magnet temperature and preventing demagnetization despite the indirect measurement approach
3Productivity
If the motor operates at high power output, then the productivity is improved, but the permanent magnet temperature increases causing demagnetization risk
Solution Approach 1:
The patent establishes predetermined temperature thresholds and protection strategies in advance. Before the permanent magnet temperature reaches dangerous levels, the system proactively monitors stator coil temperature and preemptively adjusts motor operating parameters when thresholds are approached, preventing demagnetization before it occurs rather than reacting after damage has happened
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
Effectively prevents irreversible demagnetization of the permanent magnet by accurately predicting its temperature and adjusting the motor's operation parameters, ensuring optimal performance without the need for expensive cooling systems or direct temperature sensors.
Implementation Method 1
predicting a temperature of a permanent magnet in a motor based on a driving state of the motor
Implementation Method 2
a temperature of a coolant cooling a core of the motor, and a temperature of a coolant cooling a coil of the motor
Implementation Method 3
adjusting a switching frequency of a switching element in an inverter providing a driving power to the motor
Implementation Method 4
switching frequency of a switching element in an inverter providing a driving power to the motor
Implementation Method 5
adjusting a current command of the motor based on the temperature of the permanent magnet
Data Source
AI summary
An iron loss reduction control apparatus for motor permanent magnet overtemperature protection is provided. The apparatus includes: a permanent magnet temperature prediction unit configured to predict a temperature of a permanent magnet in a motor based on a driving state of the motor; a first iron loss reduction unit configured to adjust a switching frequency of a switching element in an inverter providing a driving power to the motor based on the temperature of the permanent magnet; and a second iron loss reduction unit configured to adjust a current command of the motor based on the temperature of the permanent magnet.