Tapani Jokinen

Induction and permanent-magnet synchronous machines for high-speed applications

Solid-rotor induction motors are mechanically very robust and therefore potential candidates for highspeed electric drives. Permanent magnet machines offer better electromagnetic characteristics. These two types of machine are compared for high-speed applications. Electromagnetic, thermal and mechanical aspects are discussed. The permanent magnet machines are considered to be the best solution for applications in which the surface speed of the rotor remains below 250 m/s. For very large speeds and powers, a solid-rotor induction motor is preferred

Magnetic Shape Memory materials-new possibilities to create force and movement by magnetic fields

In the paper, a new class of actuator materials, their working principles and some applications are presented. The materials are active and they are called magnetic shape memory (MSM) materials. They can, theoretically, develop, in a magnetic field, large and precise controlled strains up to 20%. Actuators made from MSM can replace conventional electromagnetic devices in many applications.

A hybrid PBIL-based harmony search method

The harmony search (HS) method is a popular meta-heuristic optimization algorithm, which has been extensively employed to handle various engineering problems. However, it sometimes fails to offer a satisfactory convergence performance under certain circumstances. In this paper, we propose and study a hybrid HS approach, HS–PBIL, by merging the HS together with the population-based incremental learning (PBIL). Numerical simulations demonstrate that our HS–PBIL is well capable of outperforming the regular HS method in dealing with nonlinear function optimization and a practical wind generator optimization problem.

Analysis of a voltage regulator for a two-phase induction motor drive

This paper presents the modelling and experimental studies, underlying the analysis of a novel voltage regulator which is used as a supply for a variable speed two-phase induction motor drive. A median point inverter with full logic control is used as a voltage regulator. The machine stator windings have a special distribution. This voltage regulator drive achieves a wide speed range in both directions. As supply a lead-acid battery or a bridge rectifier connected to the AC supply voltage can be used.

Modeling and simulation of electric drive systems using Matlab/Simulink environments

This paper describes a complete modeling and simulation realization on a closed loop induction servomotor drive based on the Matlab/Simulink environment. A simple modeling approach for different types of inverters, based on the dynamic node technique is proposed and a servomotor drive library is described. Based on this library, a speed sensor and/or speed sensorless vector control strategy can be implemented and tested.

Demagnetisation state of permanent magnets in large output power permanent magnet synchronous motor

This paper describes the design of a large output power permanent magnet synchronous motor with radial flux distribution. In this paper, two different permanent magnet motor configurations were analysed. Numerical calculations of motor characteristics were performed with a two-dimensional finite element, time-stepping simulation program. The results are presented and the advantages and disadvantages of each rotor construction are discussed.

A New Harmony Search method in optimal wind generator design

The Harmony Search (HS) method is an emerging meta-heuristic optimization algorithm. However, like most of the evolutionary computation techniques, it does not store or utilize the useful knowledge gained during its search procedure in an efficient way. In this paper, we propose and study a new optimization approach, in which the HS method is merged together with the Cultural Algorithm (CA). Our modified HS method, namely HS-CA, has the feature of embedded problem-solving knowledge. The HS-CA is further employed in an optimal wind generator design problem, and it can yield a superior optimization performance over the original HS method.

Modeling and analysis of a two-phase induction machine with nonorthogonal stator windings

This paper extends the stationary reference frame of P.C. Krausse et al. (1995), to the modeling and analysis of the torque behavior of a two-phase unsymmetrical induction machine with a shifted auxiliary winding. By computer simulation, compared with experimental results, the influence of the electrical auxiliary phase stator shift over the machines torque and currents is verified. The analysis is made for steady-state and transient state operation. The two-phase induction machine (TPIM) is widely used in many light-duty applications where three-phase supply is not readily available. During the development of such a machine, there are several options, including the spatial placement of the auxiliary winding. The torque-slip characteristics can be manipulated by shifting the auxiliary winding from the quadrature position. The analysis of the single-phase or two-phase induction machine with a shifted auxiliary winding was made by including time domain equivalent circuit, symmetrical components, or multiple reference frames. The first two methods are acceptable for analyzing the steady-state performance of the machine, while the third method involves too many equations and variables in order to describe the dynamic performance of the TPIM.

Coupled analytical and 3D numerical thermal analysis of a TEFC induction motor

This paper presents a coupled analytical and numerical thermal analysis of a 37 kW induction motor. The approach employed combines thermal network modelling with 3D numerical thermal analysis to predict the accurate temperature distribution in the motor. This is achieved by modelling convective heat transfer numerically, aided by analytically calculated heat transfer coefficients that have been calibrated against temperature measurement data. The created lumped thermal network models the machine well with temperature results that closely match the measurements. 3D FEM steady-state thermal solution of the motors surface temperatures further corroborates these results. This approach allows the modeling of heat transfer mechanisms in the common industrial TEFC motor with relative computational ease, and can further become the basis for transient thermal analysis of the machine.

Combined Simulink-finite elements approach to inverter driven induction motor

This paper presents the modeling of a PWM induction motor drive by means of Matlab/Simulink package. The input parameters are calculated accurately by a harmonic finite element analysis. The coupled Simulink-finite elements approach is validated by simulating the unloaded starting.