High Component Count Research Articles

Single-chip inverter for active filters

Generally inverter-based active filters, which employ pulse-width-modulated (PWM) techniques, use microprocessors for overall control and discrete logic for the generation of switching patterns. Because of the complexity of control required, discrete logic circuits tend to have a very high component count, making system design inflexible, expensive and less reliable than integrated circuit implementation. The work reported here presents a novel design of a single-chip controlled PWM inverter-based active filter, which addresses these issues.

Voltage source inverters for high-power, variable-voltage DC power sources

The paper discusses the applications of voltage source inverter (VSI) based power electronic systems for interfacing variable-voltage DC sources to the grid. A variable-speed wind power conversion system is used for illustration, where the VSI-based interface needs to convert a variable DC voltage to a nearly constant AC voltage with high-quality power. The power control principles of VSI are described. Various system configurations and switching strategies are examined by analysis, simulation and experimental methods. It is shown that better utilisation of semiconductors and more flexible control may be achieved by using a separately controlled DC link, rather than a directly connected VSI that has to operate at a lower modulation ratio at higher power. In some cases, multipulse inverter structures may be preferred, despite higher component count, because of reduced switching losses, fault tolerance and the absence of filters. The solutions developed in the study could be applied at a different scale to other renewable energy sources, such as wave or solar photovoltaic devices.

Digital signal processor controlled auxiliary commutated pole converter for high performance motor drives applications

Resonant and soft-switched inverter drives offer the potential for increased switching frequencies, reduced weight and lower levels of electromagnetic interference when compared to conventional hard-switched drives. Regrettably, low-cost, soft-switching topologies such as resonant link designs suffer from poor control performance while others, such as the ACPI, have a high component count and relatively complex control structures. A low-cost commutation control scheme is proposed for the ACPI, which uses a digital signal processor to determine the optimum switching instants for both auxiliary and main devices. Results are presented comparing the performance of the DSP controlled ACPI with an equivalent hard-switched converter.

A multiphase series-resonant converter with a new topology and a reduced number of thyristors

Multiphase series resonant (SR) power converters provide a flexible way to transform power between a utility grid and a multiphase load or source. The current implementations all suffer from a high component count, which makes the use of these power converters unattractive from an economical point of view. A new topology for multiphase SR power converters has been proposed in the literature in a simulation context. This topology uses half the number of power semiconductors compared to the existing multiphase SR power converters. The present paper addresses the implementation of the new topology in a prototype power converter. The old and new topologies are presented. The operation of the new topology is explained. In the new topology the resonant circuit is grounded at one side, which compared to the old topology imposes a restriction on the operation. The paper shows both simulation data and measured waveforms. It is explained that the economical gain due to the reduction in component count is offset by a lower power rating. The paper finishes with conclusions and acknowledgments.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Optical design of a digital switch

An optical design of a time multiplexed nonblocking space switch is described for optically nonlinear arrays of logic devices interconnected in free space. Regular interconnects in the form of crossovers are used for interconnecting optical logic devices, and some efficiency is lost due to the strict use of regular interconnects. It is shown that for this application, the higher component count is comparable with the component count for the electronic implementation of the switch. We maintain that for a high bandwidth application such as packet switching, simple bulk optics provides a suitable medium for interconnecting optical logic devices even at high speeds, and that a more elaborate approach is not warranted.

A New VLSI Graphics Coprocessor-The Intel 82786

Most graphics systems available today suffer from low performance, minimal flecibility, or high cost and high component count. Intel carefully looked at these problems and designed the 82786 chip to address them. The 82786 combines into a single of supporting today's graphics standards and a powerful display processor that supports windowing in hardware.

Microprocessors Provide Speech to Instruments

Speech processing has started to find increasing application in many fields including instrumentation and process control. Microprocessors can provide a handy, compact and low-cost solution to speech synthesis problems provided they are fast and have an instruction set designed for signal processing applications. Bit-slice architecture can be an alternative to such dedicated processors, however because of the difficulties of having to write the complicated micro-code and of having higher component count, it has not found the favour of speech researchers. Recently, Texas Instruments have come up with an extremely fast microcomputer (TMS 320) which can be utilized effectively in many speech processing and other real-time applications. Some features of TMS 320 are also highlighted in this paper with reference to the bandwidth reduction that it may offer for digital transmission and storage of speech signal.