Safe and time-optimized power transfer between two induction loads supplied by a single generator

The paper deals with the problem of transferring power between different induction loads supplied by the same current generator, in as a short time as possible. In the reference solution, the system is completely stopped: it needs a long time for the current to reach zero, and then its new value, because the DC link inductance must be demagnetized and remagnetized; moreover an auxiliary starter is needed. In the proposed solution, the input of the current inverter is short-circuited whenever a transfer must be performed; the inductance remains magnetized and the current at the output of the inverter varies very quickly: the transfer time is minimal and no starter is needed; the specific inverter control laws used to insure natural commutation are described. The paper also presents average models of the system, obtained by combining average and dynamic or static first harmonic modelling methods