L Umanand

L Umanand

by abhishek

L Umanand

Faculty Advisor

Umanand is a Professor at the Department of Electronic Systems Engineering of the Indian Institute of Science, Bangalore, India. His research activities are based on the broad scope of “reduction in rate of entropy rise”. Towards this direction, the focus is on reduction in end use energy, increase in energy efficiencies of systems and shifting applications from concentrated high density fossil fuel based paradigm to diffuse low density renewable energy based paradigm. In keeping with the above framework, his research work revolves around power and energy systems with an emphasis on societal benefits. Most of the activities revolve around food, water and power. Some of his significant research work are summarized below:

Solar cooking : A significant challenge in energy transport is to bring heat energy obtained from the sun to the kitchen for cooking purposes. Energy transferred from solar insolation to the cooking load has to be optimized in order to maximize the overall efficiency. This is addressed by a dual optimization approach, viz. (i) optimizing efficiency of energy transferred from the collector to an energy buffer tank, (ii) optimizing efficiency of energy transferred from the buffer tank to the load. The optimization is performed by means of a maximum power point tracking (MPPT) algorithm for a specific performance index. Modeling the system using bond graph, development of a design toolbox and a novel low flow measurement technique are the significant outcomes of this research effort.

Modelling nonlinear electromagnetic devices : Bond graph model of a generalised multiphase electromagnetic device with magnetic non-idealities addresses the need for a model that includes magnetic non-idealities in electromagnetic devices. The work starts from the basic theory of energy port to conceptualise the generalised model of an electromagnetic device from physical correspondence. A new field element has been proposed which is called the Axis rotator. It helps distinguish between the various classes of electromagnetic devices. The constitution of the Axis rotator helps in deriving the various special electromagnetic devices (such as the dc machine, induction machine, synchronous machine and the transformer) from a generalised model.

Photovoltaics integrated microgrid : An area which we have been working on for some time now is in integrating distributed renewable energy generating devices like photovoltaics, wind turbines, pico and micro hydel systems to DC or AC microgrids. Towards this end, significant work in the areas of modelling inverter topologies, design and development of grid connected inverters and transformers has been carried out. A 25kW grid connected system has been developed entirely in-house with the help of students, wherein roof top PV pumps energy into the departmental microgrid through a novel maximum power point tracker algorithm.

Integrated magnetics : Grid interactive quality power supply (QPS) with switching arm based integrated magnetics for dynamically controlled interconnection among multiple sources and loads addresses the issues of multiple interfaces. This work proposes an integrated magnetics based compact solution that provides regulated, balanced load voltage, drawing sinusoidal and balanced currents from the grid as shown in figure (2). Series compensation is employed to ensure the quality of output voltage and shunt compensation is used to take care of the quality of the current drawn from the grid. The integrated magnetic circuit acts as a common domain for interaction between the energy ports in addition to providing galvanic isolation.

Ballast-free microhydel : Ballast-free variable-speed generation for standalone and grid-connected micro-hydel power plants is another important topic related to generation with renewable sources. Micro-hydel plants are an important source of renewable energy that can be exploited to supply requirements of local loads in remote locations while operating as a standalone source or in grid connected mode. While existing plants are based on a ballast-controlled, fixed-speed, operator-supervised model, the research work here introduces a ballast-free, variable-speed generator capable of unsupervised operation. The proposed topology takes the characteristics of the turbine into account, and by running at variable speed, ensures that only as much power is generated as required by the consumer load. This eliminates the ballast load and associated problems present in conventional plants. The generator can be connected to the grid, if present, enabling the available power to be fully utilised.

Rimless wheel walker : Another related area is in multi-terrain electric locomotion. Investigations on dynamics and control of a rimless wheel based 2D dynamic walker using pulsed torque actuation was taken up. It addressed issues related to locomotion using rimless wheels. Wheeled systems are energy efficient on prepared surfaces like roads and tracks. Legged systems are capable of traversing different terrains but can be lossy. At low speeds and on off-road surfaces, legged systems using dynamic walking can be efficient. Towards this objective, the dynamics of the walker needs to be modelled and controlled. This work analyses and experiments with the dynamics and control of a rimless wheel based mobile robot.
Umanand obtained B.E. degree in Electronics and Communication from Bangalore University in 1987 and M.Tech and Ph.D degrees from the Indian Institute of Science, Bangalore in 1989 and 1996 respectively. He received Gold Medals for his work both at the BE and MTech levels.

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