Vector-controlled induction motor drive with a self-commissioningscheme

Different vector-controlled structures are discussed, and their suitability for an economical and reliable industrial drive system is explored. From this, the design of a compact control hardware is derived, composed of an 80196 microcontroller and an ASIC (application-specific integrated circuit) for the generation of the pulsewidth modulation (PWM) signals. The drive system can be configured from a host computer or a hand-held servicing unit through a serial data link. Monitoring and diagnostic functions are included. A self-commissioning scheme permits the setting of the parameters for optimum dynamic performance of the induction motor. Various oscillograms demonstrate the behavior of the vector controller operating a 25-kVA PWM inverter     

Controlled AC drives with ride-through capability at powerinterruption

General purpose PWM inverter drives are equipped with an undervoltage protection mechanism, causing the system to shut down within a few milliseconds after a power interruption in the mains. This may entail loss or damage of material in such critical applications as the production of textile fibers, paper, or with extruder drives. The proposed solution to this problem is to recover some of the mechanical energy stored in the rotating masses. When a power interruption occurs, a sequence of fast feedforward commands is applied to force an immediate transition into the regeneration mode. During the interrupt interval, the drive system continues to operate at almost zero torque, just regenerating a minor amount of power to cover the electrical losses in the inverter. The method is implemented in an additional software package to be used with general-purpose inverter drives of limited dynamic performance. Experimental results are presented     

UV resonance Raman-selective amide vibrational enhancement: quantitative methodology for determining protein secondary structure

We have directly determined the amide band resonance Raman spectra of the "average" pure alpha-helix, beta-sheet, and unordered secondary structures by exciting within the amide pi-->pi* transitions at 206.5 nm. The Raman spectra are dominated by the amide bands of the peptide backbone. We have empirically determined the average pure alpha-helix, beta-sheet, and unordered resonance Raman spectra from the amide resonance Raman spectra of 13 proteins with well-known X-ray crystal structures. We demonstrate that we can simultaneously utilize the amide I, II, and III bands and the Calpha-H amide bending vibrations of these average secondary structure spectra to directly determine protein secondary structure. The UV Raman method appears to be complementary, and in some cases superior, to the existing methods, such as CD, VCD, and absorption spectroscopy. In addition, the spectra are immune to the light-scattering artifacts that plague CD, VCD, and IR absorption measurements. Thus, it will be possible to examine proteins in micelles and other scattering media.