Salient Motor Flux Map Refinement for Accurate Torque Control

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Solution Overview

Problem

Existing flux mapping methods for salient motors are inadequate for high-performance control and accurate torque calculation.

Innovation Solution

An iterative method and apparatus for flux map identification that applies an initial voltage to a salient motor, followed by iteratively applying a variable voltage with a constant current change to refine the flux map, enhancing accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an initial voltage is applied to generate a flux map, then flux mapping is achieved, but the accuracy is insufficient for high-performance control

Engineering Contradiction:
Improveflux estimation accuracyVSAvoidcontrol performance
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent implements an iterative feedback process where the flux map is continuously refined. The controller applies variable voltage based on the current flux map, measures the resulting current change, and uses this feedback to update and improve the flux map in subsequent iterations, progressively enhancing flux estimation accuracy

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the voltage application strategy from a static initial voltage to a dynamic variable voltage that varies across iterations. The voltage magnitude and duration are adjusted based on the flux map refinement stage, allowing optimal excitation for different levels of precision requirements

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If existing flux mapping methods are used, then the process is simple, but the flux quantification is imprecise

Engineering Contradiction:
Improveflux quantification precisionVSAvoidmapping process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The flux mapping process is segmented into multiple discrete iterations, each focusing on refining specific aspects of the flux map. The process divides the complex task of accurate flux quantification into manageable steps: initial mapping, iterative refinement with variable voltage, and convergence validation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs a preliminary initial flux mapping before the iterative refinement process. This preliminary action establishes a baseline flux map that guides the subsequent variable voltage application, making the overall process more systematic and manageable

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If variable voltage is iteratively applied to refine the flux map, then flux mapping accuracy improves, but the process time increases

Engineering Contradiction:
Improveflux map accuracyVSAvoididentification process time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies partial action by performing a limited number of iterative refinements rather than continuing indefinitely. The process stops when convergence criteria are met or a predetermined maximum number of iterations is reached, balancing accuracy improvement against time consumption

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The flux map refinement employs periodic action through discrete iterative cycles. Each iteration consists of a complete cycle: apply variable voltage, measure current change, update flux map. This periodic structure allows systematic progression toward accuracy while maintaining controllable timing

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP3975417B1Iterative flux identification
Publication Date: 2026.04.29 ROCKWELL AUTOMATION TECH INC
  • EP3975417B1 patent drawingFigure 1A
  • EP3975417B1 patent drawingFigure 1B
  • EP3975417B1 patent drawingFigure 1C

AI summary

For flux map identification, a method applies an initial voltage to a motor. The motor is a salient motor. The method generates a flux map for the motor. The method iteratively applies a variable voltage to the motor. The variable voltage includes a constant current change calculated from the flux map. The method iteratively modifies the flux map.