Switched Reluctance Motor Rotor Positioning for Vehicle Start

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Solution Overview

Problem

Switched reluctance motors in vehicles often fail to start efficiently due to variations in rotor position, leading to insufficient torque output, especially in uphill directions, resulting in degraded start performance and increased fuel consumption.

Innovation Solution

A vehicular control apparatus that employs first and second current controls to reverse rotate the rotor, adjusting its position to optimize torque output, prioritizing the second current control for enhanced start responsiveness and reducing electric power consumption by utilizing gravitational force to facilitate reverse rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If normal current control is used to start the vehicle, then the switched reluctance motor outputs maximum torque, but the start performance is degraded when the rotor position does not align with the optimal angle

Engineering Contradiction:
Improvestart performanceVSAvoidtorque output sufficiency
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The control apparatus performs preliminary action by executing reverse rotation control before the normal start sequence. When the rotor position is detected to be outside the specified range from the target rotation angle, the system first rotates the rotor in reverse direction to bring it within the specified range, ensuring that subsequent torque generation occurs at the optimal angle for maximum efficiency

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system applies inversion by causing the rotor to rotate in the reverse direction from the normal rotation direction. This reverse rotation is executed when the rotor position is outside the optimal range, allowing the rotor to reposition itself to an angle where torque can be effectively generated, thereby converting a potentially failed start attempt into a successful one

Inventive Principle:
Principle #13The other way round (Inversion)

2Use of energy by moving object

If the rotor rotates in reverse direction by stopping excitation and using gravitational force, then electric power consumption is reduced, but the reverse rotation may not occur if the vehicle is on level ground

Engineering Contradiction:
Improveelectric power consumptionVSAvoidreverse rotation occurrence
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The system applies self-service by utilizing the vehicle's own gravitational force to drive the reverse rotation of the rotor. When the vehicle is on an incline, gravity naturally causes the rotor to rotate in the reverse direction without requiring additional energy input, thereby achieving repositioning while minimizing electric power consumption

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The control apparatus monitors rotor position as a critical parameter and changes the operational state based on this parameter. When the rotor position is detected to be outside the specified range from the target rotation angle, the system transitions from normal operation mode to reverse rotation control mode, adjusting the excitation state and rotation direction accordingly to optimize both energy consumption and rotation reliability

Inventive Principle:
Principle #35Parameter changes

3Speed

If second current control is prioritized over first current control, then start responsiveness is improved, but the control complexity increases

Engineering Contradiction:
Improvestart responsivenessVSAvoidcontrol logic complexity
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The control apparatus applies dynamics by making the control strategy adaptive based on real-time rotor position feedback. The system dynamically switches between prioritizing second current control (when rotor position is outside the specified range) and normal control sequences (when rotor position is within the specified range), allowing optimal responsiveness while managing control complexity through condition-based decision making

Inventive Principle:
Principle #15Dynamics

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

Improves vehicle start performance by increasing torque output and reducing fuel consumption through strategic rotor positioning and control methods, ensuring efficient starting even in uphill conditions.

Implementation Method 1

cause the rotor to rotate in the reverse direction by a gravitational force that acts on the vehicle

Methodology Applied
Scientific EffectGravitational force: Gravitation

Data Source

PatentEP3045345B1Vehicular control apparatus
Publication Date: 2020.02.19 TOYOTA JIDOSHA KK
  • EP3045345B1 patent drawingFigure 1
  • EP3045345B1 patent drawingFigure 2
  • EP3045345B1 patent drawingFigure 3~4

AI summary

A vehicular control apparatus that includes a switched reluctance motor (2) and an electronic control unit (4) is provided. The switched reluctance motor (2) has a rotor (22) and a stator (21) and is mounted as a travel drive source in a vehicle (101). The electronic control unit (4) executes current control of the switched reluctance motor (2). The electronic control unit (4) executes first current control for causing the rotor (22) to rotate in a reverse direction from a rotational direction in which the vehicle (101) is started in the case where the vehicle (101) is not started even when the switched reluctance motor (2) outputs maximum torque within an allowable range, and executes control for causing the rotor (22) to rotate in the rotational direction in which the vehicle (101) is started after the rotor (22) rotates in the reverse direction by the first current control to a rotation position at which torque for enabling a start of the vehicle (101) can be output.