Different solutions of predictive control for two synchronous machines in parallel

The parallel operation of two synchronous machines connected to the same inverter requires taking into account information from both electrical machines to, on the one hand, ensure the stability of the whole system, and secondly to control energy efficiency. The classical approach is based on a master-slave procedure, where the master machine will be piloted while the second is simply connected in parallel. For the master machine it is then possible to determine the best control configuration of the inverter in order to minimize a criterion related to the current error. In this paper we propose three alternatives of predictive control, based on an evaluation of a global criterion taking into account sequentially or simultaneously the operating point of each machine. The control laws are then compared in terms of performances and losses. A fourth control law is proposed considering a single criterion applied to both machines at the same time. This last control law considers a large number of virtual control vectors whose enforcement is carried out through a modulation technique, such as SV-PWM. Digital simulation results obtained via Matlab-Simulink are showed for a low power application (800 W).