摘要:

The paper concerns a battery charger that has been developed for use in a battery powered electric road vehicle. The object is to charge the 144 V traction battery directly from the 220 V supply by drawing sinusoidal current at the input, to obtain, a high efficiency and to have transformer isolation from the supply. To achieve this, the rectified 220 V supply is chopped up to 500 V by a DC to DC convertor and transformed to the necessary voltage for battery charging by using a high-frequency self-oscillating inverter with magnetic feedback. The rectified output of the inverter charges the battery. The step-up chopper controls the transmitted power to the battery and ensures a sinusoidal line current. A detailed description of the power circuit is given and the capabilities of the complete system are proved by extensive measurements.

DOI:10.1049/ip-b.1986.0027

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The suitability of multistacked imbricated permanent-magnet rotors for use with a range of magnet materials is discussed and the optimal balance between parameters is assessed using a discrete-reluctance method and a 3-dimensional finite-element field analysis program. The effects of different permanent-magnet materials including the recently developed neodymium-iron compounds on the design of the imbricated rotor are described. It is shown that this configuration of rotor is suitable for high-torque applications making use of recently developed materials for excitation and a design is presented.

DOI:10.1049/ip-b.1986.0028

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The calculation of electromagnetic force in electromechanical devices usually requires accurate values of field quantities. This can be expensive in terms of computational effort and manpower. By using a complementary finite-element approach it is possible to significantly reduce the effort needed, and provide an error estimation on the solutions obtained. The technique is applied to practical problems to demonstrate its efficiency.

DOI:10.1049/ip-b.1986.0029

出版商:IEE    

年代:1986

数据来源: IET

摘要:

A general method is described for calculating the current drawn by an inverter from its DC source. It has special relevance to pulse-width modulated inverters and allows the ripple current rating of the filter capacitor to be specified with some precision. The method is for an inverter of any number of phases and uses switching functions derived from the harmonic coefficients of the inverter waveform. Experimental results from single- and 3-phase inverters demonstrate the validity of the method. Some generalised results are presented for a 3-phase inverter for the special case where the output current can be assumed to be the fundamental component only. Variation of the DC link current harmonics with power factor of the load and depth of modulation under these conditions is presented and discussed.

DOI:10.1049/ip-b.1986.0030

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The paper deals with the applications of a chopper to the thyristor Scherbius which recovers slip power of a wound rotor induction machine. An analysis of the steady-state performance of this system is presented. The chopper improves in several characteristics of a conventional system. In particular, the low power factor, which is a disadvantage of the thyristor Scherbius, is significantly improved. A reasonable operation of the chopper can realise a shorter overlapping interval at the commutation of a thyristor inverter. The recovery current controlled by the chopper has the pulse-width modulated (PWM) waveform. Such a PWM wave-form can reduce the size of line filter for the waveform shaping. Theoretical and experimental results concerning the chopper controlled thyristor Scherbius system are presented.

DOI:10.1049/ip-b.1986.0031

出版商:IEE    

年代:1986

数据来源: IET

摘要:

In the paper, the numerically computed variation of normalised permeance and force with apparent tooth flux density (tooth pitch flux/tooth area) is given for identically slotted doubly-salient structures. In the computations, a commercial steelB-Hcharacteristics is used. The data cover the range of structural variables encountered in most commercial stepping motors. Flux densities reaching heavy saturation (up to 2 T) are considered. The variables in presenting the data are chosen to be dimensionless or size independent to facilitate application to a wide range of practical motor structures. The effect of structural variables on torque under different levels of saturation is investigated from the curves and the conclusions are presented. An analytical method of static torque and inductance curve prediction for identically slotted doubly salient devices based on numerically calculated force and permeance data is also developed and applied to heavily saturated stepping motors. The results are found to be in very good agreement with the measurements. The method thus provides designers with an accurate and versatile tool.

DOI:10.1049/ip-b.1986.0032

出版商:IEE    

年代:1986

数据来源: IET

摘要:

A new high-voltage suboptimal (HVSO) pulse-width modulation (PWM) switching strategy is presented which can be used at high fundamental PWM voltages to achieve a smooth, transient-free, low harmonic distortion, transition from the PWM to quasisquare-wave mode. The design philosophy underlying the development of the new HVSO strategy is aimed at reproducing the special features and desirable characteristics of the optimised PWM strategy, using a simple and efficient microprocessor implementation. The full theoretical development of the new HVSO strategy is presented; and experimental results, from a microprocessor controlled PWM inverter drive, are provided which confirm this theoretical development. It is shown that the new HVSO strategy is superior to all existing PWM strategies, and can be implemented simply and efficiently on a microprocessor controller with only minor modifications to the existing PWM microprocessor implementations. In addition, a new hybrid PWM strategy is proposed and demonstrated, which combines the HVSO strategy with a previously developed suboptimal strategy. It is shown that this new hybrid PWM strategy can be used to cover the complete voltage/frequency range of the drive system up to and including the quasisquare wave mode, with minimised total harmonic distortion.

DOI:10.1049/ip-b.1986.0033

出版商:IEE    

年代:1986

数据来源: IET

摘要:

A partially decomposed variable-order model of the double-cage induction machine is presented and validated. The model exhibits improved computational efficiency in simulating full machine behaviour including stator transients. A state variable transformation is used to separate the electrical steady-state from the transient part of flux linkage response. The transient flux-linkage response is next decomposed into fast and slow sub-systems which constitute the boundary layers of the overall model. The fast subsystem is then reduced by neglecting the heavily damped fast transients caused by the starting cage. Each of the two decoupled boundary layer equations may be computed using different time steps and even ignored during periods when the corresponding mode is not excited, thereby effectively reducing model order and greatly decreasing computational requirements while retaining simulation accuracy.

DOI:10.1049/ip-b.1986.0034

出版商:IEE    

年代:1986

数据来源: IET

摘要:

Thyristor controlled reactors (TCRs) are a relatively new source of harmonic distortion in power systems. The steady-state balanced (or characteristic) harmonics are easily calculated and are well known. Other noncharacteristic harmonics can, however, be generated by TCRs. A detailed representation is therefore necessary which will consider all types of imbalance, be it in the TCR or in other parts of the total system to which they are connected. It is also important to consider the effect of connecting TCRs to systems which do not have a high fault level (weak AC systems) and to consider the effect of control feedback on harmonic generation. The methods by which these factors can be included in calculations of nonideal systems are the subject of this paper. The methods are illustrated by example.

DOI:10.1049/ip-b.1986.0035

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The paper presents an investigation of an unusual form of solid-pole brushless alternator as a single-phase machine. Its behaviour with pulsating single-phase fields is of particular interest. The design of the prototype alternator is discussed, with special attention being given to the design considerations of this class of machines. An analysis is presented of the nonsynchronous fields in the airgap of a salient-pole single-phase alternator. From this the fields contributing to energy conversion are identified and expressions are developed for the machine reactances. A method of calculating the leakage inductances follows from this and the additional component of leakage inductance in a single-phase machine is identified. Experimental results are presented for the machine, which include reactance measurements, a load test, heat run and voltage waveforms.

DOI:10.1049/ip-b.1986.0036

出版商:IEE    

年代:1986

数据来源: IET