Sensorless Motor Control for Inductance Estimation
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Solution Overview
Problem
Conventional motor control methods without a position sensor struggle to accurately calculate the inductance of a permanent magnet assisted synchronous reluctance motor due to the rotor position alignment issues, leading to inefficiencies in motor control.
Innovation Solution
A motor control method that adjusts voltage components, performs coordinate axis conversions, and generates three-phase excitation currents to drive the motor to a rotating position, allowing for the estimation of rotor position and subsequent calculation of effective inductance by maintaining current components at steady-state values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If conventional self-learning method is used to calculate inductance parameter, then the control device can operate without a position sensor, but the rotor position cannot be accurately aligned with the set angle leading to inaccurate inductance calculation
Solution Approach 1:
The patent implements an iterative feedback mechanism where the control device calculates rotor position based on voltage and current signals, compares it with the set angle, and adjusts the voltage command accordingly. This closed-loop feedback enables accurate inductance calculation without position sensors by continuously correcting the rotor position alignment through feedback from the motor's electrical signals.
2Device complexity
If the control device estimates rotor position based on drive voltage and current, then the system can function without additional sensors, but the rotor position alignment with set angle becomes difficult to achieve accurately
Solution Approach 1:
The patent replaces the mechanical position sensor system with an electrical field-based estimation approach. By using voltage and current signals from the motor's electrical system to calculate rotor position through coordinate transformations and mathematical models, the invention substitutes mechanical sensing with electrical measurement, achieving sensorless operation while maintaining position alignment accuracy through iterative correction.
Data Source
AI summary
A motor control method includes the following steps: adjusting a voltage component of an estimated voltage command to a steady-state voltage value; performing a coordinate axis conversion on another voltage component of the estimated voltage command and the steady-state voltage value, and generating a three-phase excitation current to make a synchronous motor rotate to a rotating position and stop; calculating an estimated current signal; calculating an estimated value of the rotating position and adjusting the another voltage component of the estimated voltage command when determining that the current component is not maintained at a steady-state current value; calculating an effective inductance of the synchronous motor based on the steady-state voltage value, the another voltage component of the estimated voltage command, the steady-state current value, and another current component of the estimated current signal when determining that the current component is maintained at the steady-state current value.