The operation of ac drives in applications requiring high overload capability imposes hard working conditions on the electronic switching devices. The use of induction motors with two stator windings, fed by two inverter modules, allows large power rating in variable speed drives for high performance applications. This paper shows the structure and the main features of a fieldoriented control for a double winding motor, fed by two GTO inverters.The operational results of a 850 kW drive, working as a melt pump in a polyethylene plant, are reported in order to describe the obtained performances.

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The ever-increasing demand for electrical power and the tremendous growth of renewable energy sources in the past decade has led designers to design wind turbine system components for optimal performance. Cost optimization, weight reduction, higher performances, and lower non-conformance cost are a few expectations that components are expected to meet in the present market condition. Wind turbine system unavailability impacts the annual energy production of the wind turbine. Overheating of the wind turbine system components is one of the main challenges to overcome. For the heating analysis, we discuss the wind turbine generator as a specific example in this article. This approach is equally valid for other components of wind turbine systems, with heat exchanger. Windings and bearings are the two main components susceptible to failure in the generator for wind turbine applications. The root cause may vary from case to case, but overheating accelerates the generator’s windings and bearing failure and in many cases is the prime reason behind. Running the components at higher load points is one of the reasons for components to overheat. The article presents a solution to improve the performance of the wind turbine system and at the same time making it a commercially attractive choice. This can be achieved by reducing generator windings and bearings operating temperature, and also reducing its cost and weight at the same time. The proposed solution to reduce overheating is achieved and verified through results. The achieved results also explain how one solution is advantageous over the other.

As the state-of-the-art technology for energy saving, variable-frequency drives (VFDs) can be applied in nuclear power plant to drive recirculation pumps for coolant flow control. Due to requirement of high reliability, such as in nuclear industry, air natural convection cooling plays an important role in and while brings out a great challenge to thermal management for electronic unit. With an application of single board computer module in control system, another cooling challenge comes from heat flux increase caused from smaller footprint, since all of components, such as processor, chipset, memory and power supply etc., are built into one board. In the paper, cooling technologies for the single board computer module are investigated and developed, focusing on natural air heat convection from heat sink to ambient and heat conduction from board to heat sink. Based on thermal analysis associated with mechanical consideration, one heat sink is used to cool multiple components on the board. Two TIMs (thermal interface materials) and one heat spreader are employed for heat conduction from CPU and chipset to heat sink, respectively. Extrusion heat sink is selected with a comprehensive consideration of cost and thermal performance. A numerical simulation model is developed and validated against testing results. With the verified model, effects of fin arrangement on heat sink performance are analyzed. A study is conducted for optimization of base plate and fin thickness, and accordingly a heat sink is developed for the present application. Environmental conditions, such as temperature, altitude, and humidity etc., are analyzed to investigate their influence on cooling performance of natural air convection.