Juliette Soulard

Determination of d and q reactances of permanent-magnet synchronous motors without measurements of the rotor position

The interest in permanent-magnet synchronous motors (PMSMs) is increasing in a wide area of applications. Since most PMSMs will operate without a shaft sensor in the future, valuable information for experimental determination of machine parameters will be lost. In this paper, therefore, a method is presented where the induced EMF and the d-axis reactance are determined in a no-load test and the q-axis reactance is determined in a load test. The load angle /spl delta/ is determined from the load test by means of a new analytical method. In this way, no separate measurement of the load angle is required. The method is especially suitable for line-start PMSMs which normally operate with negative d-axis current and, therefore, are not saturated in the d-axis flux paths. Moreover, the method is very simple to carry out for any laboratory technician, since the only tests that have to be made are standard tests which are made on standard induction motors on a regular basis.

Study of the synchronization of line-start permanent magnet synchronous motors

The synchronization process of three-phase line start permanent magnet synchronous motors (LSPM) with buried magnets and a squirrel-cage is studied in this paper. The goal is to define a pull-in criterion by using a Lyapunov function. A model is first derived and a Lyapunov function is defined using the Lagrange-Charpit method. Experiments and simulations are then compared to check the validity of the model. A criterion to define the capability of synchronization of LSPM motors is then presented. This criterion is used to study the influence of the electrical parameters on the synchronization capability of two four pole LSPM motors. The first experiments proved that the prototypes have greater synchronization capability than the criterion predicts.

A permanent magnet synchronous motor for traction applications of electric vehicles

This paper presents the design of a permanent magnet synchronous motor (PMSM) for traction applications of electric vehicles (EVs). The design is based on the stator geometry of an existing commercial available induction traction motor. The rotor configurations considered in this study are the surface mounted magnet (SPM) and the inset permanent magnet (IPM) types. Both designs are investigated for the identical specification and their overall performances are compared with the existing asynchronous motors. A schematic block diagram of the design flow chart applied is illustrated. An analytical approach for calculating stator iron loss is applied in the design procedure to ensure the required performance is reached. A thermal analysis of the prototype motor based on the lumped-circuit model and finite element analysis is also presented. Lastly, conclusions on the overall performance of PMSMs for electric vehicle applications are made and discussed.

Temperature Influence of NiFe Steel Laminations on the Characteristics of Small Slotless Permanent Magnet Machines

High performance electrical machines can operate at temperatures of 100°C and beyond in rotor and stator cores. However, magnetic properties are generally measured at room temperatures around 23°C to 25°C according to the standards, even if it is known that the magnetization of some materials is substantially influenced by increasing temperatures. This paper investigates the thermal influence on the magnetic properties and iron losses in the stator cores of small slotless permanent magnet synchronous machines (PMSMs). The stator stack is made of thin nickel iron (NiFe) lamination sheets. Magnetic measurements of the stator core are conducted for different frequencies and flux densities at several temperatures between 25°C and 105°C. The obtained measurement data is afterwards used in finite element method (FEM) simulations to investigate the influence of the magnetic property change on the machine performance. For the PMSM in consideration, the FEM simulations show that an increased stator core temperature reduces the electromagnetic torque considerably; approximately 1/3 of the torque reduction due to increased rotor magnet and stator core temperatures (from 25°C to 100°C) can be attributed to the increased stator core temperature.

Parametric study of a transverse flux wind generator at no-load using three-dimensional finite element analysis

This paper deals with the three-dimensional static and dynamic finite element analysis of a transverse flux generator at no-load conditions used in offshore wind turbines. Two transverse flux topologies, namely the basic topology and that utilizing iron bridges are analyzed. The parametric study with respect to the flux linkage and pole-to-pole flux leakage is conducted for various combinations of dimensions in static finite element analysis. The magnitudes and waveforms of the flux linkage and the induced emf obtained in the dynamic finite element simulations are compared with the analytical and static simulation results.

Comparison between different ways to calculate the induced no-load voltage of PM synchronous motors using finite element methods

In this paper two different ways of calculating the induced no-load voltage of permanent magnet synchronous motors (PMSM), by the use of a finite element method (FEM) program, have been compared. Neither of the two calculation methods require a FEM software package that can perform time-stepping. The number of required static FEM-calculations is limited to just a few, or even to one. The calculations are performed on five motor geometries. The results are compared to values obtained from time-stepping FEM-calculations, and to the measured induced no-load voltages of the five manufactured prototype motors. It can be seen that the least time-consuming method is accurate enough in most of these cases. The exceptions, in this study, are when there are relatively large airgaps and/or when the stator teeth are saturated.

Influence of the Welding Process on the Performance of Slotless PM Motors With SiFe and NiFe Stator Laminations

The influence of the welding process during the manufacturing of small slotless permanent-magnet synchronous machines (PMSMs) is studied in this paper. The focus lies on the change of the magnetic properties in high-quality silicon-iron (SiFe) and nickel-iron (NiFe) electrical steel sheets with thicknesses of 0.1 and 0.2 mm. It is shown that the welding process changes the magnetic material properties significantly and increases the specific iron losses. Experimental results are provided for magnetic flux densities up to 1.5 T and frequencies from quasi-static to 200 Hz. The obtained measurement data is afterward used in finite-element method (FEM) simulations to investigate the influence of the magnetic property changes on the motor performance, particularly with regard to stator core losses.

Analysis of Flux Measurements on a PMSM With Non-Overlapping Concentrated Windings

In this paper, measurements of the magnetic flux in a permanent magnet synchronous machine (PMSM) with non- overlapping concentrated windings are analyzed. Flux leakage, inductances and stator iron losses are investigated from measurements performed at open-circuit, blocked-rotor, and load conditions, respectively. Comparisons of the measurements with the corresponding 3D finite-element (FE) simulations allow validating thoroughly the FE model. The zigzag leakage flux flowing from one magnet to another through a tooth tip, which is characteristic for PMSMs with concentrated windings, is highlighted and its effect on the stator iron losses is investigated.

Transverse Flux Machines for Sustainable Development - Road Transportation and Power Generation

The higher specific torque and power density of a transverse flux machine (TFM) in comparison to a conventional machine makes it a promising energy converter in various applications. In this paper, a free piston energy converter and a direct-driven wind turbine are considered. The analytical investigation of the novel TFM topology applied in these two cases is presented. The cogging torque is evaluated by use of a three-dimensional finite element method. The results of simulating generators rated in the range of 3-12 MW are discussed. Manufacturing of a linear prototype is presented.

PWM Influence on the Iron Losses and Characteristics of a Slotless Permanent-Magnet Motor With SiFe and NiFe Stator Cores

This paper investigates the influence of switching frequency and modulation index combined with welding on the iron losses in thin silicon-iron and nickel-iron lamination sheets of a small slotless permanent-magnet synchronous machine (PMSM). First, measurements are conducted on welded and nonwelded stator ring cores for switching frequencies between 1 and 20 kHz and modulation indexes of 0.4, 0.7, and 0.9, keeping constant fundamental flux density peak values. This is possible by changing the dc-link voltage of the inverter. The obtained measurement data are afterward used in finite-element method simulations to investigate the inverter influence on the performance of the PMSM.