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In this paper performance characteristic of two levels and five levels inverter fed induction motor drive are compared. Open loop control of Induction motor (IM) is used in both inverter schemes. Comparison of both schemes has been done in terms of THD in their line current. Steady state response of speed, current and torque in induction motor is also compared for both control schemes. Models are developed for SPWM and Multilevel inverter fed induction motor using Xilinx.

Distributed control system (DCS) is available in most of the compressor stations of cross-country pipeline systems. Programmable logic controller (PLC) is used in all the intermediate pigging (IP) stations/sectional valve (SV) stations to collect the field data and to control the remote actuated valves. This paper presents how DCS or PLC can be used for cathodic protection of gas pipelines. Virtual instrumentation (VI) software is used here for simulation and real-time implementation purpose. Analog input channels available in DCS/PLC can be used to measure pipe to soil potential (PSP) with the help of half-cell and voltage transducer. Logic blocks available in DCS can be used as low selector switch to select the lowest PSP. Proportional-integral (PI) controller available in DCS/PLC can be used for taking the controlling action. PI controller output varies the firing angle of AC phase controller. Phase controller output is rectified, filtered, and fed to the pipeline as cathodic protection current. Proposed scheme utilizes existing infrastructure to control pipeline corrosion.

Power management and charging of batteries for wireless sensors becomes a problem when using them in field applications. We propose a Wireless Energy Harvesting System which can be used to charge the batteries of the sensors whenever required. We are able to harvest energy from a RF source, which is mostly a Master Transceiver Unit, with input power as low as -9dBm. Also the Energy Harvester can be used to charge batteries when the input power is as low as -27dBm. Also the power management part of the system includes a Charge Pump which can handle large variation in load conditions. This charge pump can be used not only to boost the battery voltage but also to provide a regulated output independent of load conditions. Link variations can be an issue in a Wireless Sensors Network but our system introduces a low power data acquisition system that helps us monitor the link. Adjustments can be made accordingly for maximum energy transfer to take place between the TX and RX coils.