Real-time emulation for power equipment development. Part 2: The virtual machine

Abstract

Power electronic control of electromechanical systems has become common. These systems employ electronic components which switch at high frequency and have very complex interactions. The load which they supply is often intricate in itself and difficult (or often impossible) to create in an experimental environment. It would be advantageous to replace the electromechanics with a solid-state equivalent which can be flexibly programmed to emulate the real system. The paper is concerned with describing this idea, illustrating the concept by emulating an electric motor and its associated mechanical load. The phrase ‘virtual machine’ has been coined to describe the system. It gives/takes power from the electronic converter to match as closely as possible the real electrical machine and load. The virtual machine is effectively a dynamically controllable source/sink which is capable of providing a bidirectional power level interface to a power electronic converter. Using the virtual machine, a power electronic converter can be tested in diverse applications and under a wide variety of loading conditions without the need for any electromechanics. Test results show that close agreement between the virtual and real systems is possible. The limits imposed by practical implementation of the concept are also examined.