This paper describes a single current sensing technique that uses only one DC link current sensing resistor to measure the three phase motor currents, therefore, reducing the cost of whole system. However, in certain conditions, current pulse width in the shunt resistor is very narrow and the measurement becomes difficult. This paper proposed a new strategy to solve this problem by changing PWM switching frequency and using double reference voltage vector PWM technique. The realization of the proposed single current sensing method based on the ADMCF341 DSP, which is specifically designed for easy implementation of single current sensing technique, is described. Simulation and experimental results are prese nted.

A simple stator fault detector for ac motors, based on the TMC320C243 DSP controller is presented. The detector provides compensation of the constructional and supply voltage imbalances, and, senses the ripple of the compensated instantaneous, power. The power ripple is indicative of such stator faults as open and short circuits in the stator winding. The low-cost detector is expected to give an early warning of an impending stator failure in inexpensive industrial and domestic ac motor drives. Details of implementation and results of experimental investigation are described.

Stator faults, such as the inter-turn, inter-phase, and phase-to-ground short circuits, or a broken connection in one or more phases, constitute the most common cause of failure of three-phase ac motors. In many instances, especially these involving critical drives, an early warning of the impending drive stoppage is crucial, allowing task re-scheduling to avoid costly process interruptions. Although serious faults usually result in immediate tripping of the motor, some of them may spread slowly, so that the motor can still run for certain amount of time. The challenge is to catch a fault as early as possible, utilizing only the stator current and voltage signals [1],[2].

A novel random pulse width modulator with varying switching frequency but constant sampling frequency is proposed for application in voltage source inverters for adjustable-speed ac drives. Harmonic Spread Factor is introduced for quality evaluation of voltage spectra of inverters with the random PWM. Realization of the modulator using the Texas Instruments' TMS320F240 DSP controller is described and the results of simulations and experiments are presented.

A novel random pulse width modulator with variable switching frequency but constant sampling frequency is proposed for application in voltage source inverters for adjustable-speed AC drives. The decoupling of these two frequencies allows the optimal sampling ratio for closed-loop control purposes to be maintained, while the randomly varying switching ratio results in the transfer of harmonic power of the inverter output voltage into the continuous power density. This mitigates the undesirable acoustic, vibration, and EMI phenomena associated with fixed-frequency switching. A novel, so-called harmonic spread factor is introduced for quality evaluation of voltage spectra of inverters with random PWM. Practical realization of the modulator using the TMS320F240 DSP controller is described, and the results of simulations and experiments are presented.

Herpes simplex virus 1 (HSV-1) glycoprotein B (gB) is a multifunctional glycoprotein required for infectivity; it is thought to promote fusion of the viral envelope with the cell membrane and entry of virions into cells. To map the antigenic and functional domains on gB, we constructed amino terminal derivatives lacking the entire carboxyl terminus and internal deletion mutants lacking defined regions of the extracellular and transmembrane domains. Transient expression of the mutants in COS-1 cells revealed that the amino terminal derivatives were released into the medium whereas those with deletions in the extracellular domain were mostly retained within the transfected cells. Analysis of intact gB and the amino terminal derivatives showed that the intact molecule formed dimers whereas the mutant derivatives did not. Reactions of the derivatives with a panel of well-characterized monoclonal antibodies to gB showed that the neutralizing epitopes cluster in two domains. The first maps in the amino terminal 190 residues and contains seven continuous epitopes, five of which are HSV-1-specific. Reactions of antibodies with a set of oligopeptides fine-mapped the epitopes between residues 1 and 47. The second domain is composed of discontinuous epitopes and was expressed by amino terminal derivatives that were at least 457 residues in length or longer. Eleven epitopes map in this region, including those of four potent neutralizing antibodies whose cognitive sites mapped between residues 273 and 298 in mapping studies using antibody-resistant mutants. Results of the present study indicate that the cognitive sites of these antibodies are assembled into the discontinuous domain by juxtaposing residues from the amino-terminal half of gB monomers.

Cytomegalovirus (CMV) encodes several glycoproteins reported to be structural homologues of glycoproteins encoded by herpes simplex virus type 1 (HSV-1). To map the antigenic and functional domains on the 907 amino acid CMV glycoprotein B (gB), we cloned and expressed a subfragment of BamHI fragment R of the CMV (Towne) genome into an expression vector and reacted the resulting gene product with a panel of monoclonal antibodies. Our results showed that the DNA fragment encodes related glycoproteins which we previously designated gA and which others have reported to be homologous to HSV-1 gB in CMV (AD169). Analyses of the processing of CMV gB transiently expressed in eukaryotic cells showed that glycosylation occurred independently of viral infection. Ten antibodies with complement-dependent and independent neutralizing activity reacted with a truncated derivative of gB that contained 619 amino-terminal residues but lacked the transmembrane and intracellular regions of the molecule. Twelve additional antibodies reacted with a CHO cell line expressing a 680 amino-terminal derivative of gB. All of the reactive antibodies precipitated the 447 residue carboxy-terminal cleavage product of gB from extracts of CMV-infected cells. These results showed that the neutralizing epitopes map in at least two domains of gB which are located in a discontinuous segment of 219 amino acids between residues 461 and 680 from the amino terminus of the molecule.

To characterize the domains of HSV-1 glycoprotein B (gB), we isolated mutants resistant to monoclonal antibodies with potent neutralizing activity. Partial nucleotide sequencing of the mutations revealed that gB contains two domains comprising discontinuous and continuous amino acids that bind cross-reactive and type-specific neutralizing antibodies. Four mutations in a discontinuous domain, R1435, R233, R1375, and R126, contained substitutions of Tyr278 for His278, His298 for Arg298, Gln274 for Arg274, and Asn273 for Tyr273, respectively. Two mutations in a continuous domain, R1392 and R1397, contained substitutions of Thr32 for Ala32 and Thr47 for Asn47, respectively, and overlapped two other type-specific epitopes. Analysis of the nucleotide sequence of strain KOS showed differences from strain F at four residues proximal to the R1392 mutation and one residue proximal to the R1397 mutation, which explains the failure of HSV-1 (F)-specific antibodies to these epitopes to react with KOS. One target site for proteolytic cleavage of gB by cellular enzymes maps at the amino terminus, partially overlapping four HSV-1-specific epitopes.