PMSM Inductance Estimation With Controlled Phase Current Injection
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Solution Overview
Problem
Conventional PMSM parameter estimation techniques suffer from poor accuracy due to lack of control over current magnitude, leading to overloading or low signal-to-noise ratio, and fail to independently extract stator q-axis and d-axis inductances accurately.
Innovation Solution
An iterative PMSM parameter estimation methodology that revises inductance estimates until convergence is achieved, controlling phase current magnitude to maintain accuracy and precision, using a least-squares method to update estimates at each iteration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PMSM parameter estimation techniques inject excitation voltages with different frequencies and measure current responses, then parameter estimation can be performed, but current magnitude cannot be controlled leading to overloading or low signal-to-noise ratio
Solution Approach 1:
The patent implements an iterative estimation process where the controller measures current responses, compares them against expected values, and adjusts excitation voltages accordingly. This feedback mechanism enables precise control of current magnitude during parameter estimation, preventing both overloading and low signal-to-noise ratio conditions while improving measurement accuracy
Solution Approach 2:
The patent dynamically adjusts the excitation voltage magnitude and frequency during the parameter estimation process. By varying these parameters iteratively based on measured current responses, the system maintains optimal current levels that prevent saturation while ensuring sufficient signal strength for accurate measurement
2Productivity
If conventional techniques simply average calculated inductances from multiple frequency measurements, then parameter estimation can be completed, but accuracy deteriorates due to saturation effects and lack of current control
Solution Approach 1:
The patent performs preliminary assessments of motor operating conditions and saturation characteristics before conducting parameter estimation. This preliminary action allows the system to select appropriate excitation levels and frequencies that avoid saturation effects, ensuring accurate inductance measurements while maintaining efficient estimation speed
Solution Approach 2:
The patent systematically varies excitation voltage magnitude and frequency parameters during the estimation process. By changing these parameters iteratively and selecting optimal values based on measured responses, the system achieves both high measurement precision and acceptable estimation speed, avoiding the pitfalls of simple averaging methods
3Measurement precision
If iterative revision of inductance estimates is performed, then estimation accuracy improves, but computational complexity and time increase
Solution Approach 1:
The iterative estimation algorithm is self-adjusting, automatically modifying excitation parameters based on measured current responses without requiring external intervention. The system self-optimizes the estimation process by learning from each measurement cycle, achieving high accuracy while minimizing unnecessary iterations and computational overhead
Data Source
AI summary
A method of parameter estimation for a PMSM (permanent magnet synchronous motor) includes: iteratively revising an estimate of an inductance parameter of the PMSM, until the estimate either converges to a predetermined accuracy level or diverges; and controlling a magnitude of phase currents injected into the PMSM during each iteration of revising the estimate of the inductance parameter. Additional methods of PMSM parameter estimation are described, including rotor flux linkage estimation.