Howard C. Lovatt

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The introduction of rare-earth permanent magnets based on samarium-cobalt in about 1970, and neodymium-iron-boron magnets in the mid-nineteen eighties, has ushered in a new era in hard magnetic materials. This has resulted in a dramatic improvement in permanent magnet performance, with neodymium-iron-boron (Nd2Fe14B) magnets having a magnetic energy product(More)
The rugged low-cost construction and constant power profile of a switched reluctance motor (SRM) make it suitable for hybrid electric vehicles (HEVs). This paper describes the development of a voltage-based control strategy for a SRM. The controller design is influenced by project constraints and goals as well as the use of a new power topology. A prototype(More)
Hybrid electric vehicles (HEVs) powered by electric machines and an internal combustion engine (ICE) are a promising means of reducing emissions and fuel consumption without compromising vehicle functionality and driving performance. Reducing emissions is important because pollution in cities is almost entirely due to transport and is linked to the illness(More)
The advent of modern rare-earth permanent magnets, which have a magnetic energy product up to an order of magnitude greater than those of Alnico and ferrite magnets, with high remanence and coercive force, has resulted in improved performance of many devices and products. Modern rare-earth magnets, especially neodymium-iron-boron, when combined with(More)
I would like to comment on the paper by Xiang-Dang Xue et al., [1] The bicubic spline technique presented in this paper was first published in a reluctance motor context by Manzer et al., [2]. Subsequently, the technique was improved upon by Stephenson and myself in [3]. Both of these older papers discuss the more difficult task of fitting to measured data(More)
Wide-bandwidth measurements are necessary when testing electronically switched drfves. 7 b o dfficult pmblems are addressed the measurement of motor phase input power at low speed. with a high PWM modulation frequency and the measurement of small torque ripple (superlmposed on a large mean toque). In an electrlcdlY noisy envlronment. Extensive use Is made(More)
This paper describes a coniputer program which models in detail singly-salient and doubly-salient. open-loop and closed-loop. reluctance motor drives. The program is integrated into a larger suite of general modelling and design programs. Saturation. load-dynamics and the limitations of transducers are all included In the program. Validity of the program is(More)