Search

The majority of existing models for estimation and control of switched reluctance machines (SRMs) ignore the dynamic effects of mutual coupling between different phases. Although this may be acceptable for some common industrial applications, such a simplification may degrade significantly the performance of the drive and the precision of the estimated quantities. In this work an enhanced representation of the SRM is introduced, by defining an appropriate finite element model of the machine. This model enables accurate estimation of rotor position and electromagnetic torque, for any current configuration. The necessity as well as the feasibility of this approach is illustrated in the ease of a three-phase, 6/4 SRM. Torque and position estimation accuracy provided by the proposed methodology is validated by measurements on a prototype three-phase 6/4 SRM. Index Terms--Angular position estimation, electromagnetic torque estimation, finite-element-based estimator, switched reluctance machine (SRM) drives.

In this paper, a novel four-level inverter will be presented and analyzed. The proposed inverter topology, which is composed of a conventional two-level and a three-level neutral-point clamped (NPC) inverter, is suitable for high-voltage and high-power applications. The proposed inverter, when it is compared with the conventional four-level NPC pulsewidth modulation inverter, exhibits the following advantages: a) ability of changing the power losses distribution profile among the devices by selecting a suitable switching strategy; b) reduction of total inverter power semiconductor device losses; c) ability of bidirectional operation for all power semiconductor switches; and d) easy implementation using existing power semiconductor modules. The effect of conduction and switching losses profiles of the proposed inverter for different switching strategies is examined under different loads, power factors, and modulation indices. The dc-link capacitors voltages are effectively balanced via a proposed self-voltage balancing topology, without the need of isolated dc voltage sources or additional voltage stabilizing circuits. Finally, the theoretical results are confirmed by simulation and experimental results. Index Terms--DC-Link capacitor voltage balance, multilevel voltage source inverter (VSI), semiconductor device power losses, sinusoidal pulsewidth modulation (SPWM).

This paper presents a methodology for a convenient modification of induction motor equivalent circuit parameters, taking into consideration switching frequency iron losses in case of inverter supply. The method is based on the determination of harmonic iron losses in laminated iron cores under nonsinusoidal excitation by using a particular three-dimensional (3-D) finite-element model adopting a reduced scalar potential formulation. Eddy currents in iron laminations are considered by means of convenient surface current densities. Experimental verification is performed in case of a 20-kW experimental setup. Index Terms--Eddy currents, finite-element methods, harmonic analysis, iron losses.

Battery management systems (BMSs) are used in many battery-operated industrial and commercial systems to make the battery operation more efficient and the estimation of battery state nondestructive. The existing BMS techniques are examined in this paper and a new design methodology for a generalized reliable BMS is proposed. The main advantage of the proposed BMS compared to the existing systems is that it provides a fault-tolerant capability and battery protection. The proposed BMS consists of a number of smart battery modules (SBMs) each of which provides battery equalization, monitoring, and battery protection to a string of battery cells. An evaluation SBM was developed and tested in the laboratory and experimental results verify the theoretical expectations. Index Terms--Batteries, error analysis, fault diagnosis, fault tolerance, protection, reliability.

In this paper an analytical method is presented which allows the exact calculation of the rms value of the state space variables of a switching power converter, whose starting point is the unified state-space representation of the switched networks and end result is a complete form of equations that include both the DC and RMS values. The method proposed in this paper, bridges the gap, which exists between the state-space technique and the small signal approximation that departures from the steady state ripple values are negligible, compared to the steady state values themselves. A new extended circuit model is proposed whose fixed topology contains all the elements of any DC-to-DC converter, regardless of its detailed configuration, and by which different converters can be characterized in the form of a table conveniently stored in a computer data bank to provide a useful tool for computer aided design and optimization. Finally, examples are given for Buck, Boost, and Buck-Boost regulator topologies. Index Terms--Buck-boost regulator, capacitor, DC-to-DC converter, inductor, semiconductor.

The majority of existing models for estimation and control of switched reluctance machines (SRMs) ignore the dynamic effects of mutual coupling between different phases. Although this may be acceptable for some common industrial applications, such a simplification may degrade significantly the performance of the drive and the precision of the estimated quantities. In this work an enhanced representation of the SRM is introduced, by defining an appropriate finite element model of the machine. This model enables accurate estimation of rotor position and electromagnetic torque, for any current configuration. The necessity as well as the feasibility of this approach is illustrated in the case of a three-phase, 6/4 SRM. Torque and position estimation accuracy provided by the proposed methodology is validated by measurements on a prototype three-phase 6/4 SRM. [ABSTRACT FROM AUTHOR]