摘要:

The fundamental equations characterising the full-bridge zero-voltage-switched DC-DC convertor are utilised in a nonlinear design-optimisation routine. The design is subject to realistic constraints along with an objective function of minimal total and/or maximum efficiency. The routine is used to study the effects of switching frequency, leakage inductance and load range for zero-voltage switching on the efficiency and size. Maximum efficiency is shown to occur when zero-voltage switching is maintained in the immediate vicinity of full-load operation. Experimental measurements confirm computed predictions.

DOI:10.1049/ip-b.1993.0036

出版商:IEE    

年代:1993

数据来源: IET

摘要:

A phase-modulated series-parallel resonant convertor is introduced and analysed in the frequency domain using Fourier-series techniques. The convertor consists of a class-D phase-modulated series-parallel resonant inverter and a class-D rectifier. Analytical expressions are derived for various parameters of the inverter to study its behaviour. Three types of voltage-driven rectifier are considered and a simple procedure is developed for designing the convertor. The theoretical calculations are verified experimentally on a 30 W convertor.

DOI:10.1049/ip-b.1993.0037

出版商:IEE    

年代:1993

数据来源: IET

摘要:

The paper proposes a fast, versatile and easy-to-use technique for control of train despatch schedules in an electrified railway system for improving its performance following outage of a station transformer. Using the technique of event driven approach and fuzzy logic, it is shown how a set of performance indices which represent the requirements on passengers, headway, regularity, and electrical loading, are optimised during rescheduling following such outage. Without the proposed emergency control technique, the railway system under consideration exhibits unstable buildups of unserved passengers/transformer overloads. Such buildups severely restrict the system's capabilities to return to normal operation.

DOI:10.1049/ip-b.1993.0038

出版商:IEE    

年代:1993

数据来源: IET

摘要:

A novel and simple DC link voltage boosting circuit is proposed to enhance the performance of inverters for single-phase switched-reluctance motors. It consists of only two additional components to the single-phase switched-reluctance motor inverter, namely a capacitor and a diode. Except for some increase in the voltage rating of the inverter components, no change to the inverter hardware is needed. The boost circuit provides many operational advantages. It generates a high boost voltage during the current pull-up and pull-down periods and hence decreases the current rise and fall times. The boost feature thus reduces the magnitude of the negative torque pulses, increases the mean motor output power and improves the efficiency of energy recovery. The paper presents the basic operating principle of the boost circuit, a method for the sizing of the boost capacitor and the results of time stepping simulations of a boosted single-phase switched-reluctance drive. The simulated and measured results presented correlate well

DOI:10.1049/ip-b.1993.0039

出版商:IEE    

年代:1993

数据来源: IET

摘要:

The saturated permeance of teeth-airgap region in doubly-slotted magnetic structures is expressed as a product of the unsaturated one and its associated permeance saturation factor, each of which depends on only three independent variables. The normalised overlapping width of opposite teeth is introduced as a new independent variable, which makes the reduction of the number of governing parameters describing the saturation permeance variations possible and greatly relieves the permeance data storage requirement. It was found that the permeance saturation factor is strongly dependent on the normalised MMF and overlapping width of opposite teeth, but weakly depends on the ratio of tooth width and pitch. The new saturated permeance database presented is used to predict the torque/displacement curve of a variable reluctance stepping motor, and the predicted one is found to be in good agreement with measured values.

DOI:10.1049/ip-b.1993.0040

出版商:IEE    

年代:1993

数据来源: IET

摘要:

The paper presents theoretical and experimental investigations for steady-state performance of a three-phase wound-rotor series-connected self-excited induction generator (SCSEIG). This type of generator can be realised by series connection of stator and rotor windings of a slip-ring type induction machine. Self excitation may occur when a suitable capacitor bank is connected across the machine terminals. The generator produces an output voltage with a frequency of half the rotor electrical angular frequency and independent of the load conditions provided that the prime mover speed is kept constant. The well known generalised machine theory has been employed with a proper transformation, resulting in a hypothetical equivalent saliency, which produces periodically time-varying inductances needed for such generators (via the mutual coupling between rotor and stator windings). Analysis is achieved by considering saturation effects on both axes (dandq) and theoretical results were found to agree well with corresponding experimental values

DOI:10.1049/ip-b.1993.0041

出版商:IEE    

年代:1993

数据来源: IET