Slot-Less Motor Torque Control Under Magnet Temperature Drift
Solution Overview
Problem
Rotating electrical machines with slot-based armatures experience significant distortion in magnetic flux waveform, leading to a small influence of temperature changes in the magnet unit on torque, whereas slot-less armatures have a larger influence, necessitating a design that minimizes this impact.
Innovation Solution
A rotating electrical machine system with a slot-less armature configuration and a controller that adjusts the q-axis current to mitigate the effects of temperature changes in the magnet unit, using conductor-to-conductor members made of magnetic or non-magnetic materials and a power converter to maintain torque stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a slot-less armature configuration is used, then the waveform of magnetic flux interlinking to armature windings becomes closer to the waveform generated from the magnet unit, but change in magnetic flux due to temperature change has large influence on torque
Solution Approach 1:
The control device measures the actual torque output and compares it with the target torque, then adjusts the q-axis command current based on the torque error feedback. This closed-loop control compensates for torque variations caused by temperature-induced magnetic flux changes, maintaining stable torque output despite the slot-less armature's sensitivity to temperature variations.
Solution Approach 2:
The control device dynamically adjusts the q-axis command current parameter based on temperature information or induced voltage and electrical angular velocity measurements. By changing this electrical parameter in response to temperature variations, the system compensates for magnetic flux changes and maintains consistent torque performance.
2Reliability
If a typical armature with slots is used, then change in magnetic flux due to temperature change has small influence on torque, but the waveform of magnetic flux is greatly distorted
Solution Approach 1:
The control device uses torque feedback to detect deviations caused by slot-induced waveform distortion and adjusts the q-axis command current accordingly. This enables the system to maintain accurate torque control despite the magnetic flux waveform distortion inherent in slotted armature designs.
3Reliability
If q-axis command current is adjusted based on temperature information or induced voltage and electrical angular velocity, then torque stability is enhanced, but device complexity increases
Solution Approach 1:
The control device implements a feedback mechanism that uses readily available measurements (induced voltage and electrical angular velocity) or temperature information to adjust the q-axis command current. This feedback approach enhances torque stability without requiring complex additional hardware, as it utilizes existing sensors and processing capabilities.
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 effectively reduces the influence of temperature-induced magnetic flux changes on torque, enhancing the stability and efficiency of the rotating electrical machine by correcting the q-axis command current based on temperature information or induced voltage and electrical angular velocity.
Implementation Method 1
The magnet unit has a plurality of magnetic poles whose polarities are alternately arranged in a circumferential direction. The armature has a multi-phase armature winding member. A major part of the magnetic flux flows into the yoke through the teeth.
Implementation Method 2
A rotating electrical machine system with a slot-less armature configuration and a controller that adjusts the q-axis current to mitigate the effects of temperature changes in the magnet unit, using conductor-to-conductor members made of magnetic or non-magnetic materials and a power converter to maintain torque stability.
Data Source
AI summary
A stator of a rotating electrical machine has a slot-less structure. The rotating electrical machine includes a controller. The controller determines a value of a q-axis command current in accordance with requirement information and an input command value for a controlled variable of the rotating electrical machine. The requirement information includes a relationship between values of the q-axis command current and corresponding command values for the controlled variable. The controller performs a task of correcting the value of the q-axis command current to thereby restrict temperature change in a magnet unit from having an influence on the relationship between the command values for the controlled variable and the corresponding values of the q-axis command current. The controller controls an inverter to thereby adjust a value of the q-axis current flowing through an armature winding member to the corrected value of the q-axis command current.