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This paper proposes a zero-voltage-transition (ZVT) pulsewidth-modulated (PWM) synchronous buck converter, which is designed to operate at low voltage and high efficiency typically required for portable systems. A new passive auxiliary circuit that allows the main switch to operate with zero-voltage switching has been incorporated in the conventional PWM synchronous buck converter. The operation principles and detailed steady-state analysis of the ZVT PWM synchronous converter with a passive auxiliary circuit are presented. All of the semiconductor devices aside from the main switch operate under soft-switching conditions. Thus, the auxiliary circuit provides a larger overall efficiency. The feasibility of the auxiliary circuit is confirmed by the simulation and experimental results. [ABSTRACT FROM PUBLISHER]

Industrial plants are faced with stringent requirements enforced by the utility to meet power factor and power quality requirements. These plants, in order to avoid very costly penalties, have traditionally utilized switchable shunt capacitor banks with detuning reactors for power factor correction, along with a separate active harmonic filter in cases where harmonic currents are an issue as well. Alternate solutions such as SVCs and STATCOMs have been considered to be too expensive for use in industrial power conditioning applications. This paper proposes a dynamic capacitor (D-CAP) based on the family of inverter-less active filters that is able to provide a dynamically controllable capacitance with active harmonic filtering integrated into the same unit. This new device is seen to be compact, and is likely to be cost competitive against simple switched shunt capacitors. It can maintain power factor close to unity, offering dynamic capabilities better than switched capacitors or SVCs, possibly lending itself for arc-furnace type of loads. [ABSTRACT FROM PUBLISHER]

The most advanced vacuum cleaners are now using brushless drives, with operating speeds in excess of 100 000 r/min. The drives are very sophisticated, but must also be low in cost. Sensorless control is desirable, but most sensorless methods involve extensive computation, which is prohibitively expensive at such high speeds. This paper looks at a 100 000-r/min, 1600-W switched reluctance machine (SRM) and drive system using the current gradient sensorless (CGS) scheme and analyzes parameters that affect the stability of the system. Commercial products require very robust control schemes: effects such as motor magnetic saturation, speed variations, changes in advance angle, and changes in dc-link voltage are examined to determine the boundaries within which the CGS scheme is stable. Both simulation and measurements are used, demonstrating measures which ensure stable operation over the entire operating range. [ABSTRACT FROM PUBLISHER]

A near-miss shock incident occurred on a heated air blower control panel during construction activities. This paper describes the investigation and findings of the team, with follow-up items to ensure that future equipment brought to the site will be properly inspected for safe design. [ABSTRACT FROM AUTHOR]