Synchronous Reluctance Motor Torque Control With Adaptive Phase Tables

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Solution Overview

Problem

Synchronous reluctance motors face challenges in efficient torque control due to changes in the difference between d-axis and q-axis inductance, leading to fluctuations in motor torque, making it difficult to maintain high-efficiency operation.

Innovation Solution

A motor control device that utilizes tables to optimize armature current and current phase angle command values based on rotor rotation angle, allowing for precise setting of motor torque command values and distribution between stator coils to minimize torque fluctuations and maximize motor efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If vector control is used to control synchronous reluctance motor, then motor torque can be controlled, but torque fluctuates when d-axis and q-axis inductance difference changes

Engineering Contradiction:
Improvemotor torqueVSAvoidtorque stability
Core Design Contradiction:
PowerVSStability of the object's composition

Solution Approach 1:

The patent changes the control parameters from fixed armature current command value and current phase angle command value to variable values that are selected based on the detected motor torque. By using multiple sets of command values stored in tables and selecting the appropriate set based on actual torque feedback, the system adapts to changes in d-axis and q-axis inductance difference, thereby stabilizing motor torque output.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If armature current command value and current phase angle command value are held at predetermined values, then control is simple, but motor torque changes when inductance difference changes

Engineering Contradiction:
Improvecontrol complexityVSAvoidmotor torque
Core Design Contradiction:
Device complexityVSPower

Solution Approach 1:

The patent introduces feedback control where the actual motor torque is detected and used to select the appropriate armature current command value and current phase angle command value from stored tables. This feedback mechanism allows the system to maintain simple predetermined control values while adapting their selection based on actual torque conditions, resolving the contradiction between control simplicity and torque stability.

Inventive Principle:
Principle #23Feedback

3Adaptability or versatility

If d-axis and q-axis inductance difference changes with armature current and rotor angle, then motor adapts to operating conditions, but efficient torque control becomes difficult

Engineering Contradiction:
Improvemotor adaptabilityVSAvoidtorque control efficiency
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent performs preliminary action by pre-calculating and storing multiple sets of armature current command values and current phase angle command values in tables for different operating conditions. Instead of calculating optimal values in real-time, the system prepares these values in advance and simply selects the appropriate pre-calculated set based on detected motor torque, thereby maintaining both adaptability and control efficiency.

Inventive Principle:
Principle #10Preliminary 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

The solution enhances motor efficiency by stabilizing torque output and reducing fluctuations, enabling high-output performance across varying rotation speeds and directions, thus improving the overall control of reluctance torque utilizing motors.

Implementation Method 1

the reluctance torque is generated due to a difference (L d -L q ) between an inductance in the d axis direction and an inductance in the q axis direction

Methodology Applied
Scientific EffectMagnetic reluctance: Magnetic Reluctance

Data Source

PatentEP3657667B1Motor control device
Publication Date: 2024.03.27 JTEKT CORP
  • EP3657667B1 patent drawingFigure 1
  • EP3657667B1 patent drawingFigure 2
  • EP3657667B1 patent drawingFigure 3

AI summary

A motor control device includes a table in which a motor torque generated from a reluctance torque utilizing motor is stored with respect to a combination of an armature current command value and a current phase angle command value at which the motor torque is maximized for the armature current command value, a first setting portion that sets a motor torque command value that is a command value of a motor torque to be generated by the reluctance torque utilizing motor, and a second setting portion that sets, based on the table, an armature current command value and a current phase angle command value for making a motor torque that is in accordance with the motor torque command value set by the first setting portion be generated from the reluctance torque utilizing motor.