Soft-started Induction Motor Modeling and Heating Issues for Different Starting Profiles Using a Flux Linkage ABC Frame of Reference

In order to mitigate the adverse effects of starting torque transients and high inrush currents in induction motors, a popular method is to use electronically controlled soft-starting voltages utilizing series-connected silicon-controlled rectifiers (SCRs). Investigation of semioptimum soft-starting voltage profiles was implemented using a flux linkage ABC frame of reference model of a soft-started three-phase induction motor. A state-space model of the soft-starter thyristor switching sequence for the motor and load was developed and implemented in a time-domain simulation to examine winding heating and shaft stress issues for different starting profiles. Simulation results of line starts and soft starts were compared with measured data through which validation of the model was established. In this paper, different induction machine soft-start profiles are shown, and comparisons of starting times, torque profiles, and heating losses are made. Discussion of these results and conclusions as to the near-optimum types of profiles are delineated based on peak torque, starting times, and winding heating criteri

Guest Editorial: Resilient and Compact Powertrains for On-the-Move Electrical Energy Technologies

The articles in this special section focus on resilient and compact power trains for on-the-move electrical energy techniques. On-the-move electrical energy technologies typically operate off the grid with no or minimal interaction with the utility network. These systems should therefore be light and compact to minimize power consumption and increase the operational time in transportation applications. They often have resilient structures because of rapidly changing environmental conditions, and the fact total failure in some systems might be catastrophic. To reduce the cost and enhance the performance of electrical energy technologies for transportation electrification, such as more electric aircraft, electric vehicles, drones, and robots, the industry is moving toward applications with more power electronics. High power density and resilient converters are critical enablers for the transportation industry to unlock significant improvements in system weight, energy consumption, total life-cycle costs, maintainability, and overall system reliability

Soft Started Induction Motor Modeling and Heating Issues for Different Starting Profiles Using a Flux Linkage ABC-Frame of Reference

In order to mitigate adverse effects of starting torque transients and high inrush currents in induction motors, a popular method is to use electronically controlled soft starting voltages utilizing series connected silicon controlled rectifiers (SCRs). Investigation of semi-optimum soft starting voltage profiles was implemented using a flux linkage ABC-frame of reference model of a soft started three-phase induction motor. A state-space model of the soft starter thyristor switching sequence for the motor and load was developed and implemented in a time-domain simulation to examine winding heating and shaft stress issues for different starting profiles. Simulation results of line starts and soft starts were compared with measured data through which validation of the model was established. In this paper, different induction machine soft start profiles are shown and comparisons of starting times, torque profiles, and heating losses are made. Discussion of these results and conclusions as to the near-optimum types of profiles are delineated based on peak torque, starting times, and winding heating criteria

Voltage boost by neutral point supply of AC machine

International audienceA new concept of AC motor drive is proposed in this paper. It allows to boost voltage of an AC machine without supplementary components. The main idea is to wisely connect the neutral point of the AC machine to the DC power supply. With some modifications on the control algorithm, the proposed solution allows to supply the AC machine with a higher voltage than with classical inverters. The concept is general for different AC machines and different topologies of inverters. The case study of an induction motor driven by a three-phase two-level inverter is illustrated. In steady state, a factor gain up of 1.7 of maximum RMS voltage can be obtained with the proposed solution compared to a classical scheme. Experimental validation on an induction motor test bench shows the effectiveness of the proposed concept

Generation of phosphoranes derived from phosphites. A new class of phosphorus ylides leading to high E selectivity with semi-stabilizing groups in Wittig olefinations

Tosylhydrazones derived from aryl aldehydes react with t-BuOK, ClFeTPP, (MeO)3P, and aldehydes to furnish olefins with high E selectivity. These reactions occur through a Wittig-type pathway via the corresponding diazo compounds, metal carbenes and phosphorous ylides, with the water-soluble trimethyl phosphate as the byproduct. Similar reactions can also be performed using ethyl diazoacetate; however, high E selectivity was only observed in the presence of LiBr. In this case, the reaction is believed to occur via the phosphonate anion, formed through an Arbuzov reaction. Thus this olefination reaction occurs through a Horner−Wadsworth−Emmons (HWE) reaction but the phosphonate anion is generated under completely base-free conditions