摘要:

The delta inverter is a novel circuit which uses only three power transistors to produce a three-phase supply. Requiring approximately half the components of a conventional bridge inverter it therefore has potential cost and reliability advantages. The basic operating principles of the delta inverter are explained, using passive resistive and inductive loads. Some aspects of its performance are compared with a bridge inverter, and preliminary results with an induction motor are presented.

DOI:10.1049/ip-b.1980.0047

出版商:IEE    

年代:1980

数据来源: IET

摘要:

A method is presented for predicting, from physical design data, the performance of saturistor induction motors having idle bars of permanent magnet material in the rotor slots. It is shown how the analysis may be used to synthesise the physical design of a motor in order to achieve a specified starting performance. The procedure is applied to the design of a 400 Hz aircraft motor to obtain reduced starting current compared with an original cage motor, without significant detriment to its normal running performance. MeasuredB-Hloop data is presented for Alcomax III, Hycomax III and Hycomax IV materials. Test results demonstrate the validity of the treatment and the success of an experimental design incorporating bars of Hycomax III.

DOI:10.1049/ip-b.1980.0048

出版商:IEE    

年代:1980

数据来源: IET

摘要:

This paper is based on recent electrical system studies carried out on an Imperial Chemical Industries (ICI) plant located in Scotland, which derives its power supplies from both in-house generators and grid interconnection. The objective was to examine methods of improving the transient response of the industrial system under various external and internal fault conditions, with a view to improving the security of supplies to important drives and auxiliaries. High levels of plant security and enhanced synchronous-generator stabffity are normally associated with multiple-grid and in-house distribution feeders, with corresponding low values of impedance between the supply sources and motor drives. However, this paper examines all aspects of system behaviour during fault conditions and concludes that, in this instance, an improvement to overall transient performance is achieved by increasing grid feeder reactance immediately after fault inception. In the case of external faults developing on the interconnected grid, computer-aided studies show the advantage of rapidly switching out one of the grid transformer feeders. Similarly, in the event of selected internal faults occurring, study results show the improvement achieved by rapidly opening normally closed ring mains, thereby doubling the effective ring feeder reactance.

DOI:10.1049/ip-b.1980.0049

出版商:IEE    

年代:1980

数据来源: IET

摘要:

A method for the computation of the voltage distortion factor by digital computer simulation of a network and a thyristor-regulated d.c.-motor drive has been developed. The influence of higher harmonics and network and motor-armature time constants on the network voltage distortion factor has been investigated. The results obtained from the voltage distortion factor computation are represented by curve families with normalised values of network and drive parameters. A good correlation has been found between computation results and experimentally obtained values.

DOI:10.1049/ip-b.1980.0050

出版商:IEE    

年代:1980

数据来源: IET

摘要:

The paper describes a signal-processing system developed for the analysis of power-semiconductor waveforms. The system combines the acqusition versatility of a digital tiansient recorder with the computational capabilities of the microcomputer. Waveforms may be displayed, stored or processed, and various processing options are described in the paper. Problems arising from point-by-point calculations are discussed and examples of waveform analysis using thyristor and transistor chopper circuits are presented.

DOI:10.1049/ip-b.1980.0051

出版商:IEE    

年代:1980

数据来源: IET

摘要:

A formulation based on scalar potentials for the numerical solution of three-dimensional nonlinear static electromagnetic field problems is presented. The resulting equations are solved using imite elements, based on a Galerkin procedure. A general-purpose package called TOSCA has been developed, implemented and tested. Results are presented for three cases and compared with measured values.

DOI:10.1049/ip-b.1980.0052

出版商:IEE    

年代:1980

数据来源: IET

摘要:

The naturally commutated, inverter-fed synchronous machine cannot use rotational voltages for natural commutation at very low speeds, and the usual technique to overcome this is to pulse the d.c. input to the inverter. A new technique is described which makes use of transformer action between rotor and stator, the rotor being supplied from halfwave rectified a.c. Commutation is automatic and requires simpler control circuits.

DOI:10.1049/ip-b.1980.0053

出版商:IEE    

年代:1980

数据来源: IET

摘要:

Previous studies of speed changing in induction motor drives have been concerned either with varying the frequency of a sine-wave supply, or have considered steady-state or quasi-steady-state operation with inverters. The present contribution discusses various techniques for controlling the start-up performance of an induction motor system with sine-wave, 180° inverter and 120° inverter waveforms. Computed results are presented using a well tried and tested digital computer program.

DOI:10.1049/ip-b.1980.0054

出版商:IEE    

年代:1980

数据来源: IET