摘要:

The paper discusses the simulation, performance and optimum design of single-phase-to-2-phase cycloconvertors driving an induction motor. Bridge and centre-tapped circuits using triacs with double-integral control are considered. Results are presented for 2-pole induction-motor drives which may operate at speeds from 0 to 1500 rev/min. The simulation is shown to model the performance of the drives successfully, and is used to predict an optimum design. An improvement to the control algorithm at bank crossover is presented. The bridge circuit is more efficient than the centre-tapped circuit, but uses more triacs.

DOI:10.1049/ip-b.1993.0044

出版商:IEE    

年代:1993

数据来源: IET

摘要:

A generalised state-space averaging technique particularly suited to resonant convertor analysis is applied to a parallel resonant convertor topology which produces high frequency power from a DC source. The convertor uses two power transistors configured in a low-cost push-pull arrangement that features low RFI emission and high efficiency owing to the zero voltage switching and absence of circulating current in the devices. Linear state-space models for the convertor describing its harmonic and transient characteristics are derived and compared with those obtained analytically and by experiment. Good agreement is observed in both cases thus validating the models.

DOI:10.1049/ip-b.1993.0045

出版商:IEE    

年代:1993

数据来源: IET

摘要:

Multielement transformers offer the prospect of low-profile designs with low leakage inductance and good thermal properties. The performances of both high- and low-voltage transformer designs, employing toroidal cores, are evaluated in ZVS-QR (zero-voltage switching-quasiresonant) convertors. It is shown that high transformer power density and good efficiency can be achieved.

DOI:10.1049/ip-b.1993.0046

出版商:IEE    

年代:1993

数据来源: IET

摘要:

Voltage-source inverters are normally equipped with an electrolyte capacitor in their DC link. A voltage-source inverter without DC link components is proposed to eliminate the electrolytic capacitor which has a short life compared with an AC capacitor (metalised polyester film, etc.). This inverter system requires an AC filter composed ofLandCin the AC source side. In this case, the most important problem is the reduction of AC filter capacity. To achieve this reduction, the rectifier section is operated by PWM control. The waveform of the AC source current is also improved. Steady-state analysis, the calculated characteristics of the AC filter capacity and the waveforms of voltage and current are described for a 0.75 kW induction motor driven by the system. The AC filter capacity is reduced to about 38% of the rectifier without PWM. Measured waveforms are presented for a motor slip of 4%. The stability with, and without, DC link components, is also discussed.

DOI:10.1049/ip-b.1993.0047

出版商:IEE    

年代:1993

数据来源: IET

摘要:

The paper investigates the design ofH2andH∞controllers for a permanent-magnet synchronous motor drive system without using shaft-position sensor, and presents the field-weakening control algorithm of the drive system. Robust PI,H2andH∞control techniques are applied to design servo controllers. A fully digital control system under the vector control framework is constructed for experimentally verifying controller performance. The theoretical development is validated by experimental work. The paper provides a new approach for designing sensorless AC drives using currently available high performance microprocessors.

DOI:10.1049/ip-b.1993.0048

出版商:IEE    

年代:1993

数据来源: IET

摘要:

Steady-state operation of a load commutated inverter (LCI) fed synchronous motor drive is analysed by means of a digital computer based solution of the synchronous machine equations. The solution permits calculation of current, voltage, and torque waveforms and includes the effects of finite DC link inductance, saliency of the rotor and all machine resistances. The continuity constraints for steady-state operation are exploited to enable the proper initial conditions to be calculated directly, without the need for iteration. Operating points are described by the firing angleyo, and the overlap angle μ, and are computed for an assumed DC supply voltage of 1.0 per unit. The linearity of the state equations allows the normalised solutions to be scaled to obtain any desired value of torque, DC link current etc. Sample calculations are provided, showing the influence of the DC link inductance on the torque, DC link current and voltage waveforms. These are then compared with experimentally measured data taken from a 3 kVA LCI fed synchronous motor drive, and a good level of agreement is achieved.

DOI:10.1049/ip-b.1993.0049

出版商:IEE    

年代:1993

数据来源: IET

摘要:

The paper first describes a model for computing the dynamic behaviour, in particular the running torque waveform (transient or quasisteadystate), of a switched-reluctance (SR) motor under a variety of excitation conditions. An experimental method for determining the torque ripple is presented and its use for verifying the model is discussed. The computation is based on a published method for integrating the nonlinear differential equations of the SR motor. The experimental method determines the running torque waveform from current waveform measurements under running conditions and static torque measurements. Allowance is made in the measurements for mutual phase interaction in shared parts of the magnetic circuit. The new method is applicable to other types of machine in which electromagnetic torque is not produced by induction.

DOI:10.1049/ip-b.1993.0050

出版商:IEE    

年代:1993

数据来源: IET

摘要:

Pulse-width-modulated (PWM) power electronics systems often produce objectionable acoustic noise at the PWM switching frequency and multiples of it. Subjectively this noise may be reduced by randomising the switching frequency, thereby spreading the acoustic energy over a wider bandwidth. The paper presents a theoretical basis for predicting the output spectra of PWM converters under these random switching conditions. The technique is developed for a DC chopper system where theoretical spectral bands can be compared with exact spectra obtained by direct Fourier transform methods, but is then extended to three-phase applications. The paper also discusses strategies for selecting random switching sequences to improve the noise dispersion while reducing the converter's complexity.

DOI:10.1049/ip-b.1993.0051

出版商:IEE    

年代:1993

数据来源: IET

摘要:

The paper presents a prediction method for the naturally commutated induction machine drive. Analytical models of the major components of the drive scheme suitable for time-stepping simulation are developed. The adoption of a reference frame for the motor that rotates with the net flux vector enables a full account to be made for the magnetic nonlinearity in the motor's main flux path. Field-orientedd, q(FODQ) equivalent circuits for the induction machine are deduced. Both the capacitor bank and inverter models are expressed in this FODQ frame to produce compatible two-axis equivalent circuits, switching functions being evolved to represent the inverter tristate switch variables. Models for the DC link inductor and the rectifier, the latter also using switching function concepts, complete the drive system model. The system model is validated through comparison between calculated and test results obtained from an experimental rig.

DOI:10.1049/ip-b.1993.0052

出版商:IEE    

年代:1993

数据来源: IET