This paper investigates the optimized combination of rotor and stator teeth in a three-phase switched reluctance motor featuring a connected C-core topology to attain a larger winding area and, thus, a higher electrical loading capability, leading to a higher torque density. The general formulation is discussed. Additionally, the shorter flux path within the design leads to a reduced core loss. The finite element method is employed in the design and field analysis. A comparison with a conventional motor shows the superiority of the proposed configuration. The optimized design is prototyped and tested. Both static and dynamic torques are extracted. A good correlation between simulation and experimental results is observed.

Droop-controlled inverters are thought to be an excellent interface for distributed generation of future power grids. Ease of installation, fully decentralized power sharing and simple procedures for expansion/reconfiguration make this type of control attractive for practical applications, in particular for microgrids. However, such microgrids appear to exhibit instabilities severely limiting the allowed ranges of control settings. Moreover, modelling approaches based on time-scale separation, that were successfully used for decades for stability assessment of conventional power systems, appeared to be inappropriate for microgrids, calling for new methods, specific to microgrids, to be developed. In this paper, we present a method for tuning inverter control parameters (namely droop coefficients and virtual impedance) that guarantees stable operation under arbitrary interconnection of inverters to the grid. The proposed method lays the foundation for plug-and-play architectures for inverter-based microgrids.

Electric propulsion of ships has experienced steady expansion for several decades. Since the early 20th century, icebreakers have employed the flexibility and easy control of direct current (dc) motors to provide for ship operations that split ice with back and forth motion of the ship. More recently, cruise ships have employed diesel-electric propulsion systems to take advantage of the flexibility of diesel, as opposed to steam engines, and because the electric plant can also be used for hotel loads. Research vessels, ferries, tankers, and special purpose vessels have also taken advantage of increased flexibility and fuel efficiency with electric propulsion. Today, the U.S. Navy is building an “all electric” destroyer to be named “Zumwalt,” which employs two induction motors for propulsion. There are several different classes of motors that might be considered for use in ship propulsion, ranging from dc (commutator) motors through conventional induction and synchronous motors to permanent magnet synchronous machines, doubly fed machines and superconducting alternating current (ac) and acyclic homopolar machines. This review paper describes features of some of the major classes of motor that might be used in ship propulsion.

This paper proposes a stationary-frame control method for voltage unbalance compensation using Interline Photovoltaic (I-PV) power system. I-PV power systems are controlled to compensate voltage unbalance autonomously. The control system of I-PV plants mainly consists of active and reactive power droop controllers, voltage and current controllers and unbalance compensator. This approach is based on injecting negative sequence current from I-PV power plants to compensate for the unbalanced loads. Consequently, the Point of Common Coupling (PCC) voltage remains balanced and regulated. The results obtained from Matlab/Simulink based simulation demonstrate the effectiveness of the proposed method in compensation of voltage unbalance at PCC.

Differences between superconducting generators and conventional machines are identified, and ways in which superconducting machines will offer both advantages and problems are shown. Superconducting generators will have system interaction characteristics, somewhat different from those of their conventional counterparts. In general, superconducting machines will improve characteristics of the power system; their low reactances and long time constants will improve transient stability and voltage regulation. However, these also produce large fault currents and torques. If care is not taken, these machines may product interesting and perhaps destructive resonant effects on shaft lines. The author builds simple models that allow several important system integration characteristics of synchronous machines, including the differences between conventional and superconducting machines, to be discussed and understood. These include reactive power capability, transient stability, damping, voltage control, fault currents, and torques.>

Two specific applications of superconductors are considered: electric machinery (motors and generators) and transmission lines. Development work carried out with respect to both types of equipment indicates that the use of superconductors is feasible, even if only liquid-helium-cooled superconductors are considered. The high-T/sub c/ superconductors will have a beneficial impact on motors, generators, and transmission lines only if conductors with sufficient mechanical properties and current-carrying capabilities can be developed.>