Optimal control of electric drives for industrial compressors

By Giampaolo Torrisi

Power systems supplied by electrical energy are extensively used in industry, hence the problem of optimizing the energy transfer to mechanical loads is particularly of interest nowadays. In Energy SmartOps project, ETH is in charge of the "Energy Optimization" package, with a particular focus in energy transformation in mechanical and electrical/power electronics systems.

A completely general scheme of the plant in our scope is depicted in the figure: electric energy from the grid is converted in thermodynamic energy in the fluid supplied by the compressor. For the transformation, an electric drive is needed, composed of a rectifier, an inverter and an electrical motor. This structure, in fact, allows for a variable speed control of the compressor. The controllable inputs for the system are the switches in the inverters, while the outputs are the mass flow rate and the pressure supply provided by the compressor.

The goal of the project is to identify and model the losses that can occur while operating such a system and to design a software control that makes use of optimization procedures, in order to minimize the power losses in the whole chain.