Permanent Magnet Motor Pole Layout for Higher Torque Density
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Solution Overview
Problem
Conventional permanent magnet type motors face challenges in achieving higher efficiency, smaller size, lighter weight, lower noise, and lower cost, particularly due to insufficient winding space and reduced torque when magnetic flux density of rotor poles increases, and inefficiencies in drive circuits.
Innovation Solution
The motor configuration includes specific numbers of rotor and stator poles with a circumferential pitch greater than 185°, bypass magnetic paths, and multiphase voltage/current systems, along with optimized magnetic flux distribution and trapezoidal-shaped voltage/current waveforms to increase torque and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the magnetic flux density of rotor poles is increased to improve torque, then torque is improved, but winding space becomes insufficient
Solution Approach 1:
The patent divides the stator poles into multiple segments (first stator poles and second stator poles) with different functions. The first stator poles have a circumferential pitch of 180° or more to provide sufficient winding space, while the second stator poles are positioned to generate torque. This segmentation allows the motor to maintain both adequate winding space and high torque output simultaneously.
Solution Approach 2:
The patent introduces a new dimensional parameter - the circumferential pitch of stator poles - to resolve the contradiction. By setting the circumferential pitch to 180° or more, the patent creates additional spatial arrangement options that decouple the relationship between magnetic flux density and winding space, allowing high flux density to be maintained without compromising winding capacity.
2Force
If the number of stator poles is increased to improve torque, then torque is improved, but device complexity increases
Solution Approach 1:
The patent makes the first stator poles multi-functional by having them serve both as winding carriers (providing winding space) and as torque-generating elements. This universality reduces the need for additional dedicated torque-generating poles, thereby limiting the increase in device complexity while still achieving improved torque through the optimized pole arrangement.
3Use of energy by moving object
If conventional drive circuits are used to control motor, then device complexity is low, but energy efficiency is insufficient
Solution Approach 1:
The patent employs dynamic control of the multiphase voltage and current systems, where the drive circuit dynamically adjusts the electrical parameters based on the motor's operating conditions. This dynamic control optimizes energy efficiency across different load and speed conditions, while the modular multiphase architecture keeps the complexity manageable through systematic control strategies.
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 achieves significantly higher torque, efficiency, and reduced size and noise, while minimizing torque ripples and iron loss, even at high speeds, using advanced drive circuits and materials like amorphous steel sheets.
Implementation Method 1
concentrated windings WS wound around teeth of the respective stator poles, and a drive circuit DTR that supplies voltage and current to the concentrated windings
Implementation Method 2
the rotor poles PR includes a part provided at a circumferential pole boundary thereof, the part being a low flux region ROU whose flux density is low
Data Source
AI summary
The torque of a permanent magnet motor is increased. There is provided a permanent magnet type motor with concentrated windings, in which each stator pole has a circumferential pitch of 185° or more in an electric angle. In this motor, the circumferential distribution of the magnetic flux density in an air gap surface of the rotor poles PR of the permanent magnet type has an approximately trapezoidal shape. Moreover, the induced voltages of the concentrated windings of the stator have an approximately trapezoidal waveform. An approximately trapezoidal-shaped waveform current is energized in the concentrated winding of each phase. Even if the magnetic flux density is close to the maximum flux density of the soft magnetic member of the stator, large slot cross-sectional areas of the stator can be secured, thus outputting a large torque.