Materials Science Forum Vol. 856

Abstract: Three dimensional (3–D), finite–element (FE) models and original lumped–parameter networks are developed for the transient thermal analysis of a permanent magnet motor (PMM) and an induction motor (IM) specifically designed and optimized for a demanding aerospace actuation application. A systematic comparison between the two different thermal modeling approaches is carried out using different loading conditions.

Abstract: Reported here the application and design of a hydrogen fuel cell hybridized with a kinetic energy recover system for powering a city bus based on in-wheel electric traction motors and on “zero emission” energy cycle. A bus, with 25 passengers of carrying capacity, run over the European urban standard drive cycle with different road slopes is considered and simulated. Powertrain components are measured for reducing the fuel consumption and for overcoming the use of chemical batteries for traction. The energy balance between the traction consumption per a bus yearly travel and the electrical energy produced by photovoltaic devices used for hydrogen production by electrolysis is performed. The results are discussed also in terms of CO₂ emissions.

Abstract: The paper presents an investigation of the saturation and cross-saturation effects on the d-axis and q-axis reactance of the permanent magnet synchronous motors. Three configurations of the rotor are analyzed. It is shown that the magnetic flux distribution in the q-axis is greatly influenced by the saturation with the increase of the load and this changes the value of the torque load angle at a given output power.

Abstract: In this paper, a detailed analysis over a reference electric vehicle’s drive cycle of an interior Permanent Magnet Synchronous Motor (IPMSM) is implemented, in terms of motor performance, efficiency and field weakening capability. Initially, the electromagnetic field characteristics of a geometrically optimized IPMSM are investigated for various modes of operation by using a 2-D Finite Element (FE) model. In a next step, a robust hybrid torque control model, combining direct Maximum Torque per Ampere (MTPA) control, for constant torque operation and Voltage Constraint Tracking (VCT), for Field Weakening (FW) operation is developed. For proper IPMSM control, the proposed model considers motor magnetic saturation and cross coupling effects between direct (d) and quadrature (q) axes, including the inductance variation with both d and q axes current. Finally, the effectiveness of the control model has been validated through New European Drive Cycle (NEDC) operation for the investigated vehicle.

Abstract: This paper presents the design of geometrically similar switched reluctance machines based on similarity theory and scale factors techniques. The fundamental theory for the development of the proposed methodology is described. The proposed methodology is used for the design of a particular 21.6 W three phase 6/4 pole switched reluctance motor, which can be used as a special electrical machine (pump’s driving motor) in an artificial heart. In addition, a sensitivity analysis using FEM was performed in order to confirm the accuracy of the proposed method.

Abstract: The purpose of the work is to study and compare the performance of photovoltaic (PV) generators built with different types of panels and operating in real weather conditions. The paper reports the results from an experimental and theoretical study of systems with PV modules manufactured according to different technologies and using different materials. The experiment was carried out at a research platform for PV systems developed by the authors, built and located at an experimental site near the Technical University of Sofia. Based on the obtained results, comparisons are made between the different PV generators for the same operating conditions. The comparison between the theoretical and the experimental results demonstrates a good level of overlap.

Abstract: This paper will provide the design experience of a linear magnetic gear/generator set that can be incorporated with those slow-motion reciprocating renewable energy sources directly. The tubular system is equipped with one linear magnetic gears set and one linear permanent magnet generator integrated coaxially, and the external mechanical forces can be incorporated to the outer low-speed mover of the system. Through proper magnetic coupling designs, the conveyed electromagnetic energy can be coupled to the internal stator winding coils to produce the desired electric power output. By introducing the detailed three-dimensional finite element analyses and the Taguchi’s method for assisting the system design assessments, a laboratory prototype with 15 cm in diameter and 30 cm in length has been developed, and preliminary results showed that a power rating of 220 W can be achieved at a reciprocating frequency of 5 Hz along with an operational stroke of ±2.0 cm.

Abstract: In this paper, the performance of three different phase locked loop (PLL) algorithms is experimentally evaluated in a grid connected photovoltaic inverter. Robust PLL is a key requirement for ensuring system compatibility with existing grid codes. The double second order generalized integrator (DSOGI) and the decoupled double synchronous reference frame (DDSRF) PLL are compared against the conventional synchronous reference frame (SRF) PLL under grid disturbances. All synchronization algorithms are initially simulated in Matlab and subsequently transformed in discrete time for implementation in the digital controller. Grid distortions, such as phase voltage sags, frequency fluctuations and voltage harmonic distortion are emulated via a controllable three phase generator.

Abstract: Systems of heat consumption of the building with heat pump that uses low-grade heat source are investigated. Effectiveness of heat consumption systems with heat pump is concluded effective for severe climatic conditions prevailing in Russia. Characteristics of heat consumption system with heat pump and the traditional heating system are compared. In this case the heat pump is used the warmth of the environment, that is why considered operating conditions for the autumn and spring. Low inertia of heat systems with heat pump compared to traditional ones during autumn and spring proved.

Abstract: Multiple local maxima (MPPs) are presented on the P-V curve of a PV system under partial shading conditions. In general, standard maximum power point tracking (MPPT) algorithms have trouble locating the global maximum, leading often to suboptimal operation at a local MPP, and thus to decreased efficiency. In commercial inverters, this situation is mitigated by performing periodically scans of the characteristic curve to relocate the global MPP. However, this procedure entails fluctuation of the power output, as well as, short-term power losses. To limit these implications, a simple algorithm is introduced in this paper, which mathematically determines whether a PV system is partially shaded or not, thus avoiding unnecessary curve scans at uniform illumination. The proposed method needs only datasheet information and a temperature sensor, while it is applicable to any PV topology, multiple irradiance levels and is readily implemented as an enhancement to any existing MPPT algorithm.