Variable Magnetization Motor Flux Linkage Control

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Solution Overview

Problem

Conventional electric motors with boosting circuits suffer from efficiency losses, which cancel out the benefits of magnetization state control, leading to inadequate motor efficiency from electrical input to mechanical output power without additional boosting circuits.

Innovation Solution

A magnetization state control method that generates a flux linkage vector with a curved clockwise trajectory on the dq-axis plane, allowing the magnitude to change temporally, enabling efficient motor operation without an additional boosting circuit by optimizing voltage use and preventing demagnetization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a boosting circuit is added to the inverter to fill the voltage gap at high motor speeds, then the motor can operate at desired high speeds, but the boosting circuit causes continuous loss even when not operated, canceling out the efficiency benefits of magnetization state control

Engineering Contradiction:
Improvemotor speedVSAvoidboosting circuit loss
Core Design Contradiction:
SpeedVSLoss of energy

Solution Approach 1:

The patent extracts and eliminates the boosting circuit from the system by developing an alternative control method that achieves high-speed operation without requiring additional voltage boosting hardware, thereby removing the source of continuous energy loss

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the magnetization state parameter of the motor to enable efficient operation at high speeds without requiring voltage boosting, using controlled demagnetization and remagnetization strategies to maintain performance while avoiding the boosting circuit loss

Inventive Principle:
Principle #35Parameter changes

2Force

If pulse current is applied to increase magnetization level for higher torque output, then the motor can accelerate the vehicle, but the induced voltage increases to high voltage levels where the inverter can no longer provide enough voltage to drive the motor at desired speed

Engineering Contradiction:
Improvetorque outputVSAvoidmotor speed
Core Design Contradiction:
ForceVSSpeed

Solution Approach 1:

The patent dynamically adjusts the magnetization state of the motor during operation, allowing the system to transition between different magnetization levels to optimize both torque output and speed capability, avoiding the static high-voltage limitation

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent employs periodic magnetization and demagnetization cycles to maintain optimal performance, using controlled pulse currents followed by demagnetization phases to prevent voltage buildup while maintaining torque capability

Inventive Principle:
Principle #19Periodic action

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

This approach enhances motor efficiency by reducing required voltage, increasing speed range, and selecting optimal magnetization levels even at high speeds, thereby improving overall motor performance without additional hardware costs.

Implementation Method 1

a variable magnetization machine including a stator and a rotor rotating with respect to the stator

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

changing a magnetization state of the variable magnetization machine such that a trajectory of the flux linkage vector has a curved clockwise trajectory on a dq-axis plane

Methodology Applied
Scientific EffectMagnetization state control: Magnetic Hysteresis

Data Source

PatentEP3329586B1Magnetization state control method and magnetization state control device
Publication Date: 2020.11.11 NISSAN MOTOR CO LTD
  • EP3329586B1 patent drawingFigure 1
  • EP3329586B1 patent drawingFigure 2
  • EP3329586B1 patent drawingFigure 3A~3B

AI summary

A magnetization state control method for a variable magnetization machine, the method includes generating a flux linkage vector while changing a magnetization state of the variable magnetization machine such that a trajectory of the flux linkage vector has a curved clockwise trajectory on a dq-axis plane and a magnitude of the flux linkage vector temporally changes, with the dq-axis plane being a synchronous reference frame with a d-axis pointing in a direction of a permanent magnet flux and a q-axis being 90 degrees ahead of the d-axis in a rotational direction of a rotor.