Correction of Rotor Rotation Irregularity of Permanent Magnet Synchronous Motor in a Controlled Synchronous Mode

AbstractWhile the permanent magnet synchronous motor (PMSM) operation in the synchronous mode rotor speed average value coincides with current frequency in the windings by definition. However instantaneous value of rotation speed can differ from the average one significantly in the process of oscillations occurring in the PMSM rotor and stator electromechanical system. This article describes a refined mathematical model of permanent magnet synchronous motor (PMSM) operating in the synchronous rotation mode allowing to explore rotor speed oscillations arising in the synchronous mode. On the basis of the mathematical model the article provides a theoretical foundation and the example of specific implementation of one of the oscillation damping ways of the PMSM rotor with permanent-magnet excitation in the synchronous mode by introducing a current feedback to the impact on the stator phase voltage. The transfer function of the compensating device, affecting the voltage phase on the motor windings and providing a significant reduction of PMSM rotor rotation irregularity is synthesized on the basis of matrix transfer function of interrelationship between output variables and input signals

Effect of Different Winding Switching Methods on Regulating and Energetic Characteristics of Synchronous Motor with Permanent Magnet Excitation

AbstractThe article contains evaluation of effect of different winding switching methods for synchronous motor with permanent magnet excitation (SMPM) on energetic efficiency, possibility of enlarging the ranges of working speeds and torques, adaptation of regulating characteristics with the aim of using it in particular electric drive. The evaluation is performed at similar values of relative speed and relative inductance. The conditions, which make sensible the usage of 120-degree or 180-degree switching, meanwhile all considered SMPM characteristics are not worse than those under vector control, are defined. It is proved, that there is a possibility to minimize engine's energy consumption by regulating switching angle, as well as change it's mechanical characteristics. In particular, it is possible to get mechanical SMPM characteristic, typical for direct-current motor with series excitation, suitable for usage in electric traction drive

Photoluminescence intensity enhancement in SWNT aqueous suspensions due to reducing agent doping: Influence of adsorbed biopolymer

The influence of biopolymer wrapped around nanotube on the enhancement of the semiconducting single-walled carbon nanotube (SWNT) photoluminescence (PL) in aqueous suspension which increases due to the reducing agent dithiothreitol (DTT) doping effect was revealed. The greatest enhancement of PL was observed for SWNTs covered with double- or single stranded DNA (above 170%) and DTT weak influence was revealed for SWNTs:polyC suspension ( 45%). The magnitude of the PL enhancement depends also on nanotube chirality and sample aging. The behavior of PL from SWNTs covered with various polymers is explained by the different biopolymers ordering on the nanotube surface. The ordered polymer conformation on the nanotube weakens the reducing agent doping effect. The method of reducing agent doping of nanotube:biopolymer aqueous suspension can serve as a sensitive lumines- cent probe of the biopolymer ordering on the carbon nanotube and can be used to increase the sensitivity of luminescent biosensors

Aggressive impacts affecting the biodegradable ultrathin fibers based on poly(3-hydroxybutyrate), polylactide and their blends: Water sorption, hydrolysis and ozonolysis

Ultrathin electrospun fibers of pristine biopolyesters, poly(3-hydroxybutyrate) (PHB) and polylactic acid (PLA), as well as their blends, have been obtained and then explored after exposure to hydrolytic (phosphate buffer) and oxidative (ozone) media. All the fibers were obtained from a co-solvent, chloroform, by solution-mode electrospinning. The structure, morphology, and segmental dynamic behavior of the fibers have been determined by optical microscopy, SEM, ESR, and others. The isotherms of water absorption have been obtained and the deviation from linearity (the Henry low) was analyzed by the simplified model. For PHB-PLA fibers, the loss weight increments as the reaction on hydrolysis are symbate to water absorption capacity. It was shown that the ozonolysis of blend fibrils has a two-stage character which is typical for O3 consumption, namely, the pendant group’s oxidation and the autodegradation of polymer molecules with chain rupturing. The first stage of ozonolysis has a quasi-zero-order reaction. A subsequent second reaction stage comprising the back-bone destruction has a reaction order that differs from the zero order. The fibrous blend PLA/PHB ratio affects the rate of hydrolysis and ozonolysis so that the fibers with prevalent content of PLA display poor resistance to degradation in aqueous and gaseous media. © 2021 by the authors. Licensee MDPI, Basel, Switzerland