Load-commutated inverter and synchronous motor drive embodying the same

DETAILED DESCRIPTION In a load-commutated inverter system, the outgoing switch recovery time is extended by applying an auxiliary commutation voltage in series with the associated phase line in response to the gating of the incoming switch during a period initiated just before the expiration of the overlap time interval and for a duration extending by a predetermined amount beyond the normal recovery time of the outgoing switch.
The auxiliary commutation voltage has the proper magnitude, polarity and duration.
It is generated, preferably, with a saturable transformer which, also preferably, is excited by the motor terminal voltage, the excitation being triggered by a zero crossing.