REAL-TIME EMULATION FOR POWER EQUIPMENT DEVELOPMENT - PART 2 - THE VIRTUAL MACHINE

Power electronic control of electromechanical systems has become commo n. These systems employ electronic components which switch at high fre quency and have very complex interactions. The load which they supply is often intricate in itself and difficult (or often impossible) to cr eate in an experimental environment. It would be advantageous to repla ce the electromechanics with a solid-state equivalent which can be fle xibly programmed to emulate the real system. The paper is concerned wi th describing this idea, illustrating the concept by emulating an elec tric motor and its associated mechanical load. The phrase 'virtual mac hine' has been coined to describe the system. It gives/takes power fro m the electronic converter to match as closely as possible the real el ectrical machine and load. The virtual machine is effectively a dynami cally controllable source/sink which is capable of providing a bidirec tional power level interface to a power electronic converter. Using th e virtual machine, a power electronic converter can be tested in diver se applications and under a wide variety of loading conditions without the need for any electromechanics. Test results show that close agree ment between the virtual and real systems is possible. The limits impo sed by practical implementation of the concept are also examined.