Commutation circuit for load-commutated inverter induction motor drives
AssigneeWestinghouse Electric Corp.
InventorAlberto Abbondanti
Life of this patent
Estimating the term…
Abstract
In a load commutated inverter induction motor drive a parallel capacitor bank is used in part to force-commutate the thyristors of the inverter as triggered by auxiliary thyristors and turned off by the other part of the capacitor bank.
Claims8
In a load commutated inverter induction motor (LCI/IM) drive including an AC power supply, a converter for rectifying said power supply and outputting between two DC terminals, a thyristor bridge inverter for applying an AC voltage on input lines to the motor, a DC-link between said converter and said inverter, with the inverter bridge being mounted across said DC terminals, and a capacitor bank in parallel with the induction motor for providing a leading power factor;
- the combination of:
- forced-commutation means interposed between said DC terminals and the input lines of the motor;
- said forced-commutation means being actuated at low speed in relation to the oncoming and the offgoing thyristor of said bridge related to one DC terminal polarity;
- said forced-commutation means being turned off by said parallel capacitor bank;
- and
- said forced-commutation means including auxiliary capacitor means operative for forced-commutation at low speed and operative with said parallel capacitor bank above low speed in providing said leading power factor.
Dependencies are inferred from the claim text.