Stator Permanent Magnet Motor Research Articles

Analysis and Experimental Verification of a Conventional Inverter With Output LC Filter to Drive Ironless Stator Axial-Flux PM Motor

Ironless stator axial-flux permanent magnet (PM) machines are becoming a promising choice in aerospace and automotive applications. However, they come with the characteristic of extremely small armature inductance, which will result in a challenging difficulty to drive with the conventional inverter. Considering the limitation on increasing the switching frequency of high-power devices, a practical and cost-effective power circuit for driving an axial-flux ironless stator PM motor is developed for the application with high dc-link voltage, high-power level, and high fundamental frequency. A new and simple control strategy of the inverter with output inductor–capacitor ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> ) filter is studied to achieve a well steady and dynamic performance for driving ironless stator PM motors. The dual closed loop of the phase current of the motor and the branch current of capacitors ensures the stability and torque control of the system. Due to the dual-loop current regulator, the maximum torque per ampere control is achieved. Meanwhile, the sinusoidal current with low harmonic content injected into the armature winding is of great significance for improving the performance of ironless stator AFPM motor. It proves that the development of the power circuit topology and effective control method provides an available solution for ironless stator motors or high-speed motors with small inductance.

Impacts of Number of Poles and Slots on Armature Reaction and Performance of Ironless Permanent Magnet Motors

Armature reaction is considered as one of the challenging problems in on-load permanent magnet (PM) motors. Reducing the undesirable impacts of the armature reaction is necessary to improve the PM motors performance. The ironless stator PM motor is known as an appropriate choice for low armature reaction. Although in these motors, disturbing high-order harmonics of armature reaction are removed, improper winding distribution still causes asynchronous field harmonics. Choosing the number of poles and slots leads to various structures with different armature windings for ironless stator PM motors. Impacts of armature reaction upon the performance of the motors with different structures are addressed in this article. This is done using precisely and quickly by a combined analytical model. This model can model the PMs magnetic fields, the air gap magnets field, and the armature reaction field. The finite element modeling (FEM) results confirm the accuracy of the proposed analytical model. Then, the analytical method and FEM are used to predict the performance of the ironless stator PM motors with the different numbers of poles and slots. This makes it possible to suggest an appropriate number of poles and slots for lower armature reaction, lower disturbed voltage harmonics, lower torque ripple, higher output power, and higher winding distribution factor.

Cogging torque optimization and analysis of hybrid stator permanent magnet motor

In order to optimize and analyze the cogging torque of hybrid stator motor, a hybrid stator motor is taken as the research project. The axial distribution of air gap magnetic flux density was analyzed, and the analytical formula of the cogging torque of the hybrid stator motor was derived. Combined with the cogging torque analytical formula, the superposition calculation method of cogging torque of hybrid stator motor was proposed, and the correctness of the superposition calculation method was verified by simulation analysis. The silicon steel segment and the amorphous alloy segment of hybrid stator core were optimized by using the uneven air gap structure, and the optimized results of the silicon steel segment and the amorphous alloy segment were obtained by two-dimensional simulation. Based on the results of two-dimensional simulation analysis, a three-dimensional model was built for simulation analysis. After optimization, the cogging torque of the motor was weakened by 48.1% and the torque ripple was reduced by 1.32%, while the loss and output torque remained basically unchanged.

Fundamental design and analysis of a novel bipolar transverse-flux motor with stator permanent-magnet excitation

In this paper, a novel bipolar transverse flux motor with stator permanent magnet excitation is proposed based on the summary and analysis of the transverse flux motor and stator permanent magnet motor research achievements in recent years. It has been shown that the motor realizes the bipolar winding flux through the detailed analysis. The motor can be used as an inwheel motor in electric vehicles because of its external rotor and permanent magnets mounted on the stator radial surface. Secondly the basic structure and working principle of the motor are introduced. Then the relationship between the motor power and its dimensions is deduced. Thirdly the 3 dimensional finite element method(3D FEM) is used to analyze the static and transient characteristics, including the no-load magnetic field distribution and winding back EMF. Finally a three-phase 600W prototype has been made and the experimental analysis is carried out.