Magnet Motor Induced Voltage Estimation Without Rotary Auto-Tuning

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Solution Overview

Problem

Existing power conversion devices for controlling magnet motors require rotary auto-tuning to adjust the induced voltage coefficient, which increases working time and reduces estimation accuracy, especially when installed in mechanical devices.

Innovation Solution

Estimate the induced voltage coefficient using active or reactive power during the actual operation of the magnet motor, calculating first and second powers based on output voltage, current, and electric circuit coefficients to achieve accurate control without rotary auto-tuning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If rotary auto-tuning is performed to adjust the induced voltage coefficient, then estimation accuracy is improved, but working time increases

Engineering Contradiction:
Improveestimation accuracy of induced voltage coefficientVSAvoidworking time for adjustment
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system performs self-adjustment by automatically estimating and correcting the induced voltage coefficient during normal operation without requiring external intervention or separate tuning procedures. The correction value is calculated based on detected voltage and current values, enabling the system to self-optimize its control parameters.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The induced voltage coefficient is estimated and corrected in advance during initial operation or idle periods before actual load operation begins. This preliminary adjustment ensures accurate control parameters are ready when the motor starts operating under load, eliminating the need for time-consuming on-site tuning.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If rotary auto-tuning is performed to adjust the induced voltage coefficient, then control precision is improved, but the adjustment process becomes complex

Engineering Contradiction:
Improvecontrol precision of magnet motorVSAvoidcomplexity of adjustment process
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The control system automatically performs the adjustment without requiring external tuning equipment or complex manual procedures. The microprocessor unit calculates the correction value using detected voltage and current values, eliminating the need for complex external adjustment mechanisms.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces complex mechanical or manual adjustment procedures with an electronic calculation and control system. The correction value is computed using electrical measurements and control algorithms, substituting what would otherwise require complex physical tuning mechanisms.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If inductance values are used for estimation, then estimation can be performed during operation, but estimation accuracy is degraded by setting errors

Engineering Contradiction:
Improveability to estimate during operationVSAvoidestimation accuracy of induced voltage coefficient
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The system uses feedback from detected voltage and current values during actual operation to calculate and refine the induced voltage coefficient. The correction value is continuously updated based on real-time measurements, allowing the system to adapt to actual operating conditions and compensate for initial parameter inaccuracies.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent dynamically adjusts the induced voltage coefficient parameter based on actual operating conditions rather than relying on fixed manufacturer specifications. The correction value modifies the original coefficient to reflect real-time electrical characteristics, compensating for parameter drift due to temperature or other environmental factors.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4213370B1Power conversion device estimating an induced voltage coefficient
Publication Date: 2026.03.18 HITACHI IND EQUIP SYST CO LTD
  • EP4213370B1 patent drawingFigure 1
  • EP4213370B1 patent drawingFigure 2
  • EP4213370B1 patent drawingFigure 3~4

AI summary

The present invention achieves highly accurate control characteristics by estimating an induced voltage coefficient of a magnet motor without rotary auto-tuning. A first power Pc is calculated on the basis of the output voltage and output current of the magnet motor, and a second power Pc^ is calculated on the basis of the electric circuit constant, current command, output frequency, and induced voltage coefficient of the magnet motor. The induced voltage coefficient is estimated so that the calculated first power follows the second power, and the driving of the magnet motor is controlled in accordance with the induced voltage coefficient.