A high‐voltage direct current (HVDC) electric power system (EPS) has become an attractive power distribution architecture for the more electric aircraft. The structure of a typical HVDC parallel EPS ...based on the permanent magnet synchronous machine (PMSM) starter/generators (S/Gs) is proposed in this study. On the basis of this structure, the control strategy for a single PMSM S/G system is presented, which is suitable for wide‐speed operation and high‐power application. It can not only achieve both starter and generator functions but also achieve the stability of DC bus voltage. A master–slave current sharing method is derived and can be applied in the HVDC parallel system, compared with the droop‐control strategy. The validity of the proposed strategies is verified by simulation studies in a Matlab/Simulation environment.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
With less fragile power electronics integrated, the overall shipboard power system (SPS) safety level is prone to increase. In this article, the motion equation concept of a less power ...electronics-based more-electric ship is proposed to study the SPS dynamics. A wound rotor induction machine (WRIM) acts as the propulsion load, whose stator and power converter are regarded as a synthetic internal voltage vector (SIVV). The small-signal model of a WRIM-based electric drivetrain (WRIM-ED) is established in the electromechanical control timescale. Besides, the external dynamic behaviors of the propulsion load are investigated in detail according to the phase and amplitude of SIVV. The control effects of phase-locked loop (PLL), rotor speed control (RSC), and reactive power control (RPC) are taken into account. In addition, the control schemes by applying the traditional PLL-based vector control (PLL-VC) and an emulated stator voltage-oriented VC (ESVO-VC) for WRIM-ED are described. Moreover, with ESVO-VC, the expression of equivalent inertia for WRIM-ED is much simplified, and there is no need to tune the PLL controller gains. MATLAB/Simulink is applied to carry out simulations to investigate the control effects of both PLL-VC and ESVO-VC on the system dynamic performance.
This paper presents several novel concepts for compact, high-voltage, pulsed power supplies for near-term and future military systems, as well as for commercial applications. The choice for ...electrical rotating converters arises from the gap of several orders in magnitude between the levels of energy density stored kinetically and the energy density stored in magnetic, or at even lower levels, in the electric field. Such compact power supplies represent, by their designs, hybrid systems comprising two or three stages in which the voltage is amplified. In general, the first stage is a modified compulsator providing the given energy per pulse at high current and a medium voltage. The second stage represents a very high voltage capacitor as a component of a resonant system, delivering an output at a 200 kV to over 800 kV level. Cascaded transformers with different insulation connections and resonance transformers provide the means of achievement for the second stage. Even inside the compulsator, there are two stages cascade-connected, leading to high voltages. The first one is magnetically independent (decoupled) from the second one and, being short-circuited, produces an extremely high magneto-motive force which can often induce a rotation by 180/spl deg/, a very large voltage in the second winding. Practical data and comparative results are given and a comparison with the state-of-the-art machine shows that the presented designs are very advantageous and will represent a fundamental advancement in the power supplies technology.
Summary form only given, as follows. This paper presents several novel technological concepts for compact, high-voltage, pulsed power supplies for near-term and future military systems, as well as ...for commercial applications developed at the Center for Electromechanics at The University of Texas at Austin. The choice for electrical rotating converters arises from the gap of several orders in magnitude between the levels of energy density stored kinetically and the energy density stored in magnetic, or at even lower levels, in the electric field. Such compact power supplies represent, by their designs, hybrid systems comprising two or three stages in which the voltage is amplified. In general, the first stage is a modified compulsator providing the given energy per pulse at high current and a medium voltage. The second stage represents a very high voltage capacitor as a component of a resonant system, delivering an output at a 200 kV to over 800 kV level. Cascaded transformers with different insulation connections and resonance transformers provide the means of achievements for the second stage. Even inside the compulsator, there are two stages cascade-connected, leading to high voltages. The first one is magnetically independent (decoupled) from the second one and, being short-circuited, produces an extremely high magneto-motive force which can induce often a rotation by 180:, a very large voltage in the second winding. A ferro-electrical capacitor in a resonant mode completes the third stage, leading to voltages up to one million volts. Practical data and comparative results are given and a comparison with the state-of-the-art machine shows that the presented designs are very advantageous and will represent a fundamental advancement in the power supplies technology.
In this paper, we discuss applications of expert systems to electrical insulation technology. After comparison of each insulation problem in the knowledge structure, we present an example of a ...prototyped expert system: an off-line diagnosis system of high voltage motor insulation. The system was created on a Prolog machine, MELCOM PSI-2. This system is easily manipulated in the computer environment "knowledge media station" which enables insulation experts to elaborate their own systems without detailed knowledge of the expert systems.
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