Design of a three-phase multistage axial flux permanent magnet generator for wind turbine applications

Abstract

Presently, axial flux permanent magnet machines are becoming popular and are being deployed actively for low speed applications. This paper presents an improved model of a multistage axial flux permanent magnet generator (AFPMG). The multistage AFPMG consists of multiple stator and rotor discs. There are three identical 1-phase stator discs and four in-phase rotor discs in the proposed multistage AFPMG. In this research, 4 case studies were analyzed on the design of the multistage AFPMG. First, a phase shift model (PSM) positions the three 1-phase stator discs to behave as a 3-phase generator. Actually, the PSM computes phases for three stator discs in order to establish phase shift of 120• between each two phases. The implementation of the presented model in the multistage AFPMG reduces the diameter of the stator disc three times as compared to the conventional 3-phase AFPMG with identical rated specifications. Second, the voltage waveform of the AFPMG was analyzed for harmonic contents and the percentages of 3rd and 5th harmonics were computed. The test results show that 3rd and 5th harmonics were reduced to 10.7% and 0.54%, respectively, in voltage waveform. Third, the proposed multistage AFPMG was designed considering begin-to-end winding connections of the stator disc. While adopting begin-to-end connection, the number of poles of the AFPMG are doubled, which ultimately increases air-gap flux density and thus the terminal voltage of the stator disc and operating shaft speed is halved. The test results show that the torque-to-weight ratio parameter of the designed AFPMG was improved by using a begin-to-end connection for the stator disc. Fourth, the increased air-gap flux density also improves the power density parameter of the AFPMG with a begin-to-end winding connection.Moreover, a prototype model of a 1200-W multistage AFPMG was designed and fabricated while following PSM and begin-to-end winding connection and tested. Thus the test results verify the proposed model of the multistage AFPMG for wind turbine applications.

Evaluation of the technical parameters of the generator for efficient electricity generation in low-speed wind and water flows

“…The generator used in these hydropower facilities is a multi-pole, low speed generator. Radial generator with a power of 10 kW and a rotation speed of 214.3 rpm, it was observed that the voltage difference between each phase is 0.3%-1.3%, and the difference between practical and theoretical experiments is 5% [14]. In other studies, it has been noted that the use of a radial generator for wind currents with low potential energy efficiency gives good results.…”

Hybrid Weighted Least Square Multi-Verse Optimizer (WLS–MVO) Framework for Real-Time Estimation of Harmonics in Non-Linear Loads

“…Solar and wind are the most common RESs being used today for electrical energy production [38][39][40]. Modern wind turbines technologies include the usage of axial flux permanent magnet generators (AFPMSGs) instead of radial flux permanent magnet generators (RFPMGs) due to their optimum flux density, higher torque-weight ratio, higher efficiency, lightweight, and more importantly it has zero cogging torque losses [41]. In this study [42], a three-phase and multi-stage AFPMSG design is developed.…”

A Hybrid Quantum Inspired Particle Swarm Optimization and Least Square Framework for Real-time Harmonic Estimation

“…AFPMGs are replacing radial flux permanent magnet generators (RFPMGs) in modern wind turbine technologies because of the unique features unveiled by AFPMG such as higher torque-to-weight ratio, maximum power density, high efficiency, absence of cogging torque losses, compact structure, lightweight and low operation shaft speed [27]- [29]. A 3-phase, multi-stage AFPMSG [30] is designed, whose per unit voltage waveform is taken as a power signal for harmonic estimation. An oscilloscope is used to record the voltage waveform of AFPMSG at a sampling frequency of 10 kHz.…”