Stator Core Recesses for Sensorless Control
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Solution Overview
Problem
Existing rotating electric machines require positional and speed sensors for accurate torque, speed, and position control, which increases complexity and cost, whereas sensorless control methods struggle to maintain high accuracy, especially under varying load conditions.
Innovation Solution
The design incorporates a stator core with recesses or through holes in the teeth to enhance magnetic saturation, allowing for sensorless control by varying the inductance between the d-axis and q-axis, thereby improving the magnetic pole saliency ratio and enabling precise magnetic pole position detection and control without mechanical sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If positional sensor and speed sensor are used for control, then control accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical sensors (positional sensor and speed sensor) with an electrical measurement system that uses inductance detection. The magnetic pole position detection is achieved by measuring inductance variations in the stator windings, which are caused by the rotor's magnetic pole position, thereby eliminating the need for mechanical sensors.
Solution Approach 2:
The system uses the motor's own electrical characteristics (inductance variations) to detect its own state (magnetic pole position). The inductance measurement system leverages the inherent magnetic coupling between stator and rotor to provide position information without external sensors, making the system self-diagnostic.
2Measurement precision
If through holes or recesses are added to stator teeth, then magnetic saturation is enhanced and sensorless control accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The patent introduces through holes or recesses at specific locations on the stator teeth where magnetic flux concentration occurs. This local modification creates regions of controlled magnetic saturation that enhance the inductance variation signals, improving position detection accuracy only where needed rather than requiring global structural changes.
Solution Approach 2:
The patent modifies the magnetic circuit parameters by introducing air gaps (through holes or recesses) in the stator teeth. This changes the magnetic saturation characteristics and inductance values, creating more pronounced inductance variations with rotor position, thereby improving sensorless control accuracy.
3Measurement precision
If inductance variation is enhanced for better position detection, then measurement precision is improved, but magnetic saturation may cause energy losses
Solution Approach 1:
The patent introduces through holes or recesses that create localized magnetic saturation regions, but not throughout the entire stator core. This partial saturation approach provides sufficient inductance variation for accurate position detection while limiting the overall energy losses to acceptable levels.
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 configuration ensures high accuracy in magnetic pole position estimation and control even under high load conditions, reducing the need for mechanical sensors and maintaining a compact machine size, while also allowing for cost-effective production and reduced cogging.
Implementation Method 1
The design incorporates a stator core with recesses or through holes in the teeth to enhance magnetic saturation, allowing for sensorless control by varying the inductance between the d-axis and q-axis
Data Source
AI summary
A rotating electric machine includes a stator, a rotor, and a stator core. The stator core includes a plurality of teeth. Each of the teeth includes at least one of a through hole axially piercing the tooth and a recess extending from one end of the tooth to another end of the tooth in an axial direction.