Machine Learning Motor Current Correction
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Solution Overview
Problem
In motor driving apparatuses for three-phase AC motors, existing correction values for current control are fixed and do not account for interdependencies, leading to suboptimal performance and increased errors between rotor position commands and actual positions due to variations in temperature and voltage.
Innovation Solution
A machine learning apparatus that observes state variables including errors, temperature, and voltage to learn dynamic correction values for current feedback offset, inter-phase unbalance, and switching dead zone, using reinforcement learning to optimize these values in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed correction values are used for current control, then the control system is simple and stable, but the accuracy of rotor position control deteriorates under varying temperature and voltage conditions
Solution Approach 1:
The patent transforms the static correction value system into a dynamic one by introducing a machine learning apparatus that continuously learns and updates correction values based on real-time operational data. The system dynamically adjusts current feedback offset correction, inter-phase unbalance correction, and dead zone correction values according to varying temperature and voltage conditions, thereby maintaining high rotor position control accuracy without compromising system stability through progressive adaptation.
Solution Approach 2:
The machine learning apparatus enables the control system to self-optimize by automatically learning optimal correction values from operational data without requiring external manual calibration. The system performs self-diagnosis and self-adjustment of correction parameters based on observed errors between commanded and actual rotor positions, eliminating the need for periodic manual recalibration while maintaining both stability and accuracy.
2Measurement precision
If machine learning is used to dynamically adjust correction values, then rotor position control accuracy is improved, but the computational complexity and processing time increase
Solution Approach 1:
The machine learning apparatus performs preliminary learning during idle or low-load periods when computational resources are available, building up correction value models in advance. This pre-learning approach allows the system to have correction strategies ready before critical control decisions are needed, reducing real-time computational burden while maintaining high accuracy through previously learned patterns.
Solution Approach 2:
The system implements continuous feedback loops where the actual rotor position (from observers) is compared with commanded positions, and the error signals are fed back to the machine learning apparatus for ongoing refinement of correction values. This feedback mechanism enables incremental learning that progressively improves accuracy without requiring complex recomputation, as the system builds upon previously learned patterns with each new data point.
Data Source
AI summary
A machine learning apparatus includes: a state observation unit that observes a state variable including an error between a position command and an actual position of a rotor, temperature of a motor driving apparatus and the motor, and voltage of each part of the motor driving apparatus; and a learning unit that learns a current feedback offset correction value for correcting an offset in the current feedback value, an inter-current-feedback-phase unbalance correction value for correcting an unbalance between phases in the current feedback value, and a current command correction value for a dead zone for correcting a current command in order to compensate a decreased amount of current due to a dead zone by which switching elements of upper and lower arms in the same phase of an inverter for motor power supply are not simultaneously turned on, in accordance with a training data set defined by the state variable.


