Auto-Tuning Electric Motor Current Regulator Using Dynamic Inductance Detection
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Solution Overview
Problem
Current current regulators for electric machines require manual tuning, which is cumbersome and prone to inaccuracies due to the need for estimating stator resistance and inductance parameters, and lack automatic tuning of switching frequencies.
Innovation Solution
A motor control unit with a processor that auto-tunes current regulator gains by determining stator resistance, d-axis, and q-axis inductance values, and adjusts gains based on performance criteria, including switching frequencies, to generate optimal current commands for the electric motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual tuning of current regulator parameters is performed, then the tuning process can be completed, but it is cumbersome and prone to inaccuracies
Solution Approach 1:
The system performs self-tuning by automatically determining stator resistance, d-axis inductance, and q-axis inductance parameters without requiring manual intervention. The processor executes test routines and calculations autonomously to configure the current regulator parameters, eliminating the need for manual tuning operations.
Solution Approach 2:
The system performs preliminary parameter determination by executing test routines before normal operation. The processor determines stator resistance and inductance parameters in advance through automated testing and calculation, so that the current regulator is pre-configured with accurate parameters before the electric machine operates.
2Ease of manufacture
If fixed pulses are applied as voltage waveforms for inductance determination, then the process is simplified, but measurement accuracy deteriorates
Solution Approach 1:
The system uses dynamic voltage waveforms instead of fixed pulses. The processor generates variable voltage waveforms that adapt during the testing process, allowing for more accurate inductance measurements while maintaining automated operation. The voltage waveform characteristics can be adjusted based on the specific electric machine being tested.
3Productivity
If switching frequencies are not automatically tuned, then the control system is simpler, but motor performance is suboptimal
Solution Approach 1:
The system implements feedback-based switching frequency tuning. The processor monitors motor operation and automatically adjusts switching frequencies based on performance criteria and measured parameters. This closed-loop approach optimizes motor performance while the processor handles the complexity of frequency adjustment automatically.
Data Source
AI summary
In one example embodiment, a motor control unit includes a processor configured to tune a current regulator regulating a supply of electrical current to an electric motor by determining a plurality of variables, the plurality of variables including a stator resistance value, a first inductance value and a second inductance value, the stator resistance value being a resistance value of a stator of the electric motor, the first inductance value being a d-axis inductance of the electric motor and the second inductance value being a q-axis inductance of the electric motor. The processor is further configured to tune the current regulator by determining a plurality of gains based on the determined plurality of variables and generating current commands for operating the electric motor based on the determined plurality of gains.