Permanent magnet generators for renewable energy devices with wide speed range and pulsating power delivery

This paper describes the design of a direct-drive permanent-magnet generator for use in a novel sea-wave electrical generator. The basic system is briefly described and the target specification derived from the device and the wave tank performance. The design for the brushless permanent-magnet generators is then developed using SPEED PC-BDC and verified using Finite Element Analysis (PC-FEA). A diode bridge model is also tested using Portunus system simulation. Copyright © 2009 Inderscience Enterprises Ltd

Matrix analysis techniques in cage induction machines

Modern analysis techniques for electrical machines are either analytical or use finite element analysis. Both methods are implemented using computational techniques to solve the magnetic circuit and produce performance predictions. This paper puts forward a steady-state impedance matrix method for analysing a split-phase induction machine that is at the leading edge of analytical modelling of induction motors. The method is implemented and verified against an example to illustrate the asynchronous torques in a non-sinusoidal winding. In the second half of the paper it is shown how the technique can be applied to a three-phase machine and the classical per-phase model is obtained from the derivation. The steady-state model derives a mathematical rigorous equivalent circuit that includes the skew reactance term in the rotor circuit. Copyright © 2009 Inderscience Enterprises Ltd

Brushless permanent magnet DC and AC motor and synchonous reluctance motor design for racing motorcycles

There is an increasing interest in electric transportation. Most large manufacturers now produce hybrid versions of their popular models and in some countries electric cycles and scooter are now popular. Motor sport is often used to develop technology and in this paper designs for electric racing motorcycles are addressed. These are in-frame motors (rather than hub motors which can affect handling and are not as powerful). Typically 10 to 12 kW-hours of batteries can be carried on the cycle and the batteries are almost exhausted at the end of a race. Therefore very high efficiency over a range of operation is needed, but also the motors need to be compact and have high torque density. This paper examines the use of permanent magnet motors and possible designs. © 2013 IEEE

Improved Direct Torque Control method of brushless doubly-fed reluctance machines for wind turbine

Direct Torque Control (DTC) method is an excellent technique for torque and flux control for a brushless doubly-fed reluctance machine (BDFRM). The advantages of the DTC method are simple implementation, fast response and little dependence on the machine parameters. However, the conventional DTC method has high torque and flux ripple and variable switching frequency problems. This paper proposes an improved DTC method for the BDFRM when used in wind power generation systems. The Space Vector Modulation (SVM) method is used for reducing the torque and flux ripple, and also for holding constant the switching frequency of the inverter. The control method is implemented in SIMULINK®/MATLAB® and the results show that the proposed DTC method can overcome the issues and problems associated with the conventional DTC method and improve the system operation performance. © 2013 IEEE

Fault ride-through of doubly-fed induction generator with converter protection schemes

This paper from the point view of wind farm fault ride-through (FRT) capability, discusses the performance of converter protection schemes to it. Different resistor protection methods are summarized and then a new combined protection with crowbar (CB) and series dynamic resistor (SDR) is proposed. With the analysis of rotor current during fault, resistance values are calculated for practical application. The rotor high current reduction performance is simulated with MATLAB/Simulink. Fault ride-through performance including the reactive power supply, torque fluctuation and rotor speed with crowbar and series dynamic resistor are compared. The proposed method is an alternative for further protection and requirements of wind farm riding-through grid disturbances. Index Terms-Fault ride-through (FRT), Doubly-fed induction generator (DFIG), converter protection, wind generation. © 2008 IEEE

A small segmented oscillating water column using a savonius rotor turbine

This paper outlines a project which addresses the use of a small segmented oscillating water column with three sections. The turbine utilises cascaded Savonius rotors (one for each section) and this system is developed and tested for validation of the performance algorithms. It is shown that the systems can be easily described and a system developed that can generate. It would be suitable for a shoreline location such as a harbour wall, where waves are random and not orthogonal to the column. Conversion rates in the region of 20 % are tabulated for the system with an output of 25 W peak. The paper will give a full algorithm for the system while the digest outlines some crucial points with regards to the sizing and operation of the column with respect to the wave frequency and wavelength. The turbine is fully characterized - the generator is a brushless permanent magnet machine connected to a diode bridge rectifier and variable load. © 2008 IEEE

Rotor fault analysis in a doubly-fed induction generator using impedance matrix technique

© 2017 IEEE. Condition monitoring is a standard method for scheduling maintenance and ensuring that catastrophic failures do not occur in industrial motors

The Detection and Suppression of Unbalanced Magnetic Pull in Wound Rotor Induction Motors Using Pole-Specific Search Coils and Auxiliary Windings

© 2017 IEEE. This paper puts forward a concept for measuring rotor eccentricity in a wound rotor induction machine. The analysis is fully developed in the theory section, then an experimental rig is described and measurements are taken. These are compared with the calculated values. Pole-specific search windings are necessary in a wound rotor machine, because standard sideband current measurement techniques are only valid for cage induction machines. The search coils can also be used to suppress unbalanced magnetic pull

Design of large power surface-mounted permanent-magnet motors using post-assembly magnetization

This paper reports the design process for the manufacture of higher power rare-earth permanent-magnet motors using post-assembly magnetization. With these machines, difficulties can be encountered in production using normal manufacturing processes due to the high intensity of rare-earth magnets that are pre-magnetized. Post-assembly magnetization utilizes the stator windings of a permanent-magnet motor to magnetize the magnets after complete assembly (so that the problem can be solved). However, with post-assembly magnetization, some parameters such as slot-fill factor, number of turns, wire diameter, etc., must be considered for the magnetization, as well as the motor operation. The machine design should be able to meet the required specification as a motor and ensure correct magnetization is possible. In this paper, a design process is described that incorporates the design considerations for post-assembly magnetization (for the requirements for complete magnetization) together with the design requirements for successful motor operation. A 6kW surface-mounted permanent-magnet motor is designed using the proposed process, and finite element analysis verifies the feasibility of the presented method. ©2007 IEEE