Antonio Gonzalez

Design of a supercapacitor based storage system for improved elevator applications

This paper presents the design and development process of a supercapacitor storage based elevator. The main design aspects of the storage system are described: the storage system rating and the DC/DC converter design. Based on this design procedure, a supercapacitor based Energy Storage System has been developed based on a multichannel buck-boost converter. Comparing with a conventional elevation system, the designed device is able to achieve an improved efficiency, reducing grid-absorbed power and guaranteeing automatic rescue. A 5kW prototype has been developed and tested first in simulation and then experimentally, both in laboratory and in a real elevator, validating the energy storage system design and its different operation modes.

Modeling of cross-magnetization effect in interior permanent magnet machines

Electric parameters of interior permanent magnet (PM) synchronous machines have a non linear characteristic due to saturation effects. Thus, d-q axes inductances are not constant, but they vary depending on the load conditions and the current phase angle. Generally, this kind of machine is characterized by a cross-magnetization effect between axes so that an ideal uncoupled d-q model is not suitable to represent the performance of the motor. In this work a steady state coupled d-q model which takes into account these non linearities is presented. An interior PM synchronous machine is analyzed in finite elements (FE) and the flux linkages as function of current amplitude and load angle are obtained. Then, analyzing these results a non-linear d-q model is proposed.

Analysis of rotor eddy current loss in fractional slot permanent magnet machine with solid rotor back-iron

This paper analyses the eddy current losses induced in the permanent magnets and rotor back-iron which is made of a solid piece of mild steel. Time-stepping finite element method (FEM) is employed for simulation of fractional slot surface-mounted permanent magnet brushless machine having 12 slots / 10 poles and concentrated windings when the magnets are isolated / non-isolated and magnetized / unmagnetized. For the prototype machine the eddy current density analysis shows that eddy currents in the magnets are resistance limited and in the rotor back-iron they are non resistance limited. One of the major new findings is that eddy currents in the rotor back-iron are very sensitive to the changes in operation point of the BH curve of mild steel, and hence the machines with solid rotor of mild steel have to be analyzed with magnetized permanent magnets.

Analytic model of a PMSM considering spatial harmonics

This work deals with the development of a complete analytic model for a surface mounted permanent magnet synchronous machine. Magnetic field in the air-gap, electromagnetic torque and induced electromotive force EMF are represented as sum of spatial-temporal components. Furthermore, parameters of the single phase equivalent circuit are obtained also in the same way. The proposed analytical model takes into consideration the effect of the stator slots on the performance of the machine. Finally, the accuracy of the model is evaluated comparing the results with that obtained in a numerical analysis.

Co-Simulation Tools for the Permanent Magnet Machine Design Oriented to the Application

The aim of this work is to analyze the viability of using co-simulation tools in the electrical machine design process. Coupling among different simulation domains such as thermal, electromagnetic, electric or mechanical permits to optimize the machine design before a prototype is built. A conventional electric machine design consists in two steps: an initial analytic design is complemented by a more accurate FEM analysis. This work deals with the addition of a third design step in order to achieve an optimal design. Thanks to co-simulation tools, critical aspects related to the operation could be identified by the designer, so the design could be modified in order to solve any performance problem. As an example, a surface mounted permanent magnet synchronous machine design is presented for a gearless elevator application. A coupling between control, electromagnetic and mechanical domains is presented in order to evaluate the influence of the machine design parameters on the ride quality of an elevator system.

Axial flux machines modelling with the combination of 2D FEM and analytic tools

This paper deals with the development of performance analysis tools for axial flux permanent magnet machines. Modeling with 3D Finite Element Method (FEM3D) software could take too much time, and both the definition and the problem solving may be very arduous. In this work an analysis method for axial flux machines is proposed. This method consists in the combination of FEM2D simulations in the average radius plane with analytical models. The obtained results prove that the proposed method could be a very interesting option in terms of time and accuracy.

Analytic model of axial flux permanent magnet machines considering spatial harmonics

This work deals with the development of a complete analytic model for axial flux surface mounted permanent magnet synchronous machines. The magnetic field in the air-gap, the induced electromotive force EMF, the linked flux ψ and the electromagnetic torque are represented as sum of spatial-temporal components. Then, the accuracy of the model is evaluated comparing the results with those obtained in numerical analysis by 3D simulations.

Investigation of rotor eddy current losses in fractional slot PM machines with solid rotor back-iron

This work deals with the computation and analysis of the eddy current losses in fractional slot permanent magnet machines with solid back iron. Losses in the magnets and back iron are calculated for different combinations of slots and pole pairs by finite element simulations. From the comparison of the losses, how the losses change with respect to the combination is studied.

Equivalent Circuit of a Linear Induction Motor with Variable Parameters

Nowadays linear induction motors (LIM) are used in many industrial applications. The simulation of electrical machine is essential to optimise the design processes and control systems. There is a need of mathematical models of LIMs capable of predicting their performance. In this paper, the experimental characterization of a LIM prototype is presented, which is based on an equivalent circuit with variable parameters

Flux weakening of surface permanent-magnet machines in over-torque operation mode

This work deals with flux weakening operation mode of surface permanent-magnet machines. Traditionally, the flux-weakening operation mode has been used to achieve speeds beyond the rated speed with the rated voltage. The same principle can be applied to reach torques higher than the rated one. In this work flux weakening in over-torque operation mode is explained. The stator resistance influence is studied and the theory is applied in a numerical example.