Twin Induction Machines Artificial Loading Without Mechanical Coupling

This article presents an artificial loading method for induction machines using industrial static frequency converters (VFCs), low cost programmable logic controllers (PLCs) for command and control and standardized communication protocols. Possible methods of artificial loading are presented in this paper. Induction machine full load testing is very difficult, especially at high power and almost impossible for vertical axis machines. Sometimes in case of high-speed machines, also the interconnection between them can be a difficult task. Bidirectional VFC utilization can’t always be a solution for artificial loading because of high variations of grid power (voltage). Two identical IMs without mechanical interconnection driven by two identical DC bus interconnected VFCs artificial loading method is presented in this paper. The power circulation between the machines is performed via the common DC link. This opens the possibility to test machines with rated power notably larger than the lab power source rating. The rated artificial loading conditions are achieved without mechanical coupling, without VFC oversizing and using standard equipment.