Motor Saturation Parameter Identification via Voltage Injection

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Solution Overview

Problem

Current control methods for synchronous electric motors with permanent magnets do not effectively account for magnetic saturation, leading to suboptimal torque optimization due to the lack of reliable parameter identification for magnetic saturation phenomena.

Innovation Solution

A control method that identifies magnetic saturation parameters by injecting static and high-frequency voltage signals, allowing for the determination of correction factors for angle errors and optimizing torque control without requiring position sensors or complex calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If magnetic saturation is not taken into account in motor models, then control simplicity is maintained, but torque optimization is suboptimal

Engineering Contradiction:
Improvecontrol simplicityVSAvoidtorque optimization
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by identifying and storing magnetic saturation parameters before normal motor operation begins. The method performs voltage signal injections and parameter identification during a preliminary characterization phase, so that when the motor operates under saturation conditions, the pre-identified parameters enable immediate torque optimization without complex real-time calculations.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If neural networks are used to measure and adaptively decouple cross saturation effects, then measurement precision is improved, but device complexity and calculation requirements increase significantly

Engineering Contradiction:
Improvesaturation effect measurementVSAvoidcalculation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs a simplified parameter identification approach that uses elementary calculations instead of complex neural networks. The method identifies saturation parameters through simple voltage signal injections and basic signal processing, effectively replacing the computationally expensive neural network approach with a much simpler, more implementable solution that achieves sufficient measurement precision for torque optimization.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If signal injection methods are used to determine saturation influence, then measurement capability is improved, but the method is not adaptable to synchronous motors with permanent magnets

Engineering Contradiction:
Improvesaturation parameter identificationVSAvoidmotor type adaptability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent adapts the signal injection method for synchronous motors with permanent magnets by modifying the identification approach to account for the specific magnetic characteristics of PMSMs. The method changes parameters such as the voltage signal injection strategy and the parameter estimation algorithm to suit the permanent magnet motor topology, enabling accurate saturation parameter identification specifically for this motor type while maintaining the simplicity of the approach.

Inventive Principle:
Principle #35Parameter changes

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

Enables efficient torque optimization by accurately accounting for magnetic saturation, improving motor performance and reliability in variable speed drive applications.

Implementation Method 1

control method implemented in a power converter connected to an electric motor of the synchronous type with permanent magnets and making it possible to identify parameters linked to the magnetic saturation of the electric motor

Methodology Applied
Scientific EffectMagnetic saturation: Magnetic Saturation

Data Source

PatentEP2684289B1Control method implemented in a power converter and intended for identifying parameters linked to the magnetic saturation of an electric motor
Publication Date: 2018.12.12 SCHNEIDER TOSHIBA INVERTER EUROPE SAS
  • EP2684289B1 patent drawingFigure 1A~1C
  • EP2684289B1 patent drawingFigure 2A~2C
  • EP2684289B1 patent drawingFigure 3A~3C

AI summary

The invention relates to a control method implemented in a power converter comprising an inverter (INV) connected to a synchronous electric motor (M) having permanent magnets, said electric motor (M) being modeled in the power converter by a mathematical model of the currents in the electric motor expressing a flux current (ISd) and a torque current (Isq) on the basis of of magnetic-saturation parameters (ax,y). The control method consists of identifying the magnetic-saturation parameters during a learning procedure particularly consisting of applying a static voltage signal and a high-frequency voltage signal along the axis of the flux and/or the axis of the torque of the motor with a view to causing an oscillation of the current on the axis of the flux and/or on the axis of the torque.