Effect of different core materials in very low voltage induction motors for electric vehicle

The use of squirrel cage induction motor for electric vehicle (EV) has been increasingly popular than permanent magnet and brushless motors due to their independence on rare materials. However, its performance is significantly affected by the core materials. In this research, induction motors performance with various core materials (M19_24G, Arnon7, and nickel steel carpenter) are studied in very low voltage. Three phases, 50 Hz, 5 HP, 48 V induction motor were used as the propulsion force testbed applied for a golf cart EV. The aims are to identify loss distribution according to core materials and compare power density and cost. The design process firstly determines the motor specifications, then calculates the dimensions, windings, stator, and rotor slots using MATLAB. The parameters obtained are used as inputs to ANSYS Maxwell to calculate induction motor performance. Finally, the design simulations are carried out on RMxprt and 2D transient software to determine the loss characteristics of core materials. It is found that the stator winding dominates the loss distribution. Winding losses have accounted for 52-55 % of the total loss, followed by rotor winding losses around 25-27 % and losses in the core around 1-7 %. Based on the three materials tested, nickel steel carpenter and M19_24G attain the highest efficiency with 83.27 % and 83.10 %, respectively, while M19_24G and Arnon7 possess the highest power density with 0.37 kW/kg and 0.38 kW/kg whereas, in term of production cost, the Arnon7 is the lowest.

1. Introduction

This introductory chapter begins by providing examples of torts. It then discusses the aims of the law of torts, the most significant being compensation and deterrence. Part of the justification for a tort is that it identifies what actions should be avoided and deters people from engaging in them. It is essential to know that action is wrongful, but a tort action may over-deter or under-deter. It may over-deter where the perception of the chance of liability is exaggerated. It may under-deter where either the chances of somebody suing to enforce their rights are small, or where the consequences to the individual tortfeasor may be slight. Originally tort was about ‘shifting’ or ‘transferring’ the loss from the victim to the defendant (corrective justice). The defendant themselves paid compensation to the victim. However, those days are gone and we are now in an era of ‘loss distribution’. In other words, it is not the defendant himself who pays, but it will be their, or their employer’s, insurer. The chapter then considers the study of torts. Tort law is almost wholly a case-driven subject and therefore a good knowledge of the cases and what they stand for is essential. The chapter presents three steps to studying cases.

18. Vicarious liability

Vicarious liability is a system whereby an employer is liable for the torts of his employees committed in the course of employment. The principle of placing liability on the employer as well as upon the individual tortfeasor is mainly justified by the concept of loss distribution; that is, that the employer will usually be better able to distribute the loss, either through insurance or through his customers. This chapter begins with a definition of an employee. It then discusses the liability of the employee; how an employer is liable for the torts of his employee only if the act is committed ‘in the course of his employment‘; and liability for independent contractors.

PWM Strategy to Alleviate Common-Mode Voltage with Minimized Output Harmonic Distortion for Five-Level Cascaded H-Bridge Converters

High-frequency components of common-mode voltage (CMV) induce the shaft voltage and bearing current, which lead to premature failures in motors. In addition, due to non-zero average CMV, the low-frequency components of CMV, particularly the third-order harmonic component, have been reported to cause difficulties in common-mode filter design. Furthermore, the utilization of distant voltage vectors in the pulse-width modulation (PWM) with reduced CMV magnitudes gives rise to high output harmonic distortion compared to PWM ones without CMV reduction. In an attempt to solve the aforementioned issues, this article presents a PWM strategy that features reduced CMV magnitudes, zero average CMV, and improved output harmonic distortion for a five-level cascaded H-bridge (CHB) converter. In addition, the carrier rotation technique based on the phase-leg redundancy of the CHB topology is also combined with the proposed scheme to achieve equal power loss distribution among power switching devices. Both simulation and experimental results confirm that the proposed strategy produces better output harmonic distortion than that of POD-SPWM and APOD-SPWM under the condition of reduced CMV magnitudes, zero average CMV, and equal power loss distribution.

On the design of sovereign bond-backed securities

In this paper, we analyze Sovereign Bond-Backed Securities in the Euro area, concentrating our attention on the return of the different tranches and on their riskiness. We show that as the correlation level among States increases, the yield rate of senior tranches increases while the yield rate of junior tranches decreases. A similar effect is observed when introducing a block dependence structure with high correlation among States belonging to the same block. Introducing a nonzero recovery rate, as opposed to a null recovery rate, decreases the yield rate of senior tranches and increases the yield rate of junior tranches. We compute the loss distribution and the Value at Risk (VaR) associated with the market risk of retaining the different tranches of the bond. We also analyze the possibility of reaching a safe asset through pooling tranches of government bonds of different States. In summary, we show that the issue in reaching a comprehensive and safe offering through the securitization of government bonds is not the safety of senior tranches but the risk of the junior ones.