US 4,475,150 A · Coordinated load commutated inverter protection system

Abstract

A fault protective system for a load commutated inverter motor drive including an AC to DC source side converter coupled from an AC source to a DC to AC load side converter via a DC link circuit and wherein the load side converter supplies AC power of varying magnitude and frequency to the synchronous motor load. A pair of microcomputers interlinked by a common digital memory respectively control the inverters and interface with hardware type sensor means for detecting the occurrence of a plurality of different types of faults. Additionally, a number of stored instructional sets or programs are respectively included in both microcomputers to detect by software means another plurality of faults. The detection of a fault on either side of the link circuit is communicated to the respective computer which subsequently communicates with the other microcomputer to effect a coordinated protective action in response to thyristor cell failures, circuit failures, and abnormal operating conditions. Cell failure faluts include those instances where a thyristor cell actually fails due to an open or short circuit as well as those cases where a cell fails to commutate properly due to firing strategy problems. Cirucit failures include open and short circuits both in the supply line and the motor leads, while abnormal operating conditions involve such things as low line voltage or excessive motor voltage.

Claims38

Dependent claims

A method of protecting a power conversion system coupled to an AC load and including an AC to DC source side converter coupled from an AC source to a DC to AC load side converter via a DC link circuit and comprising the steps of:

(a) detecting a plurality of system faults by selectively located voltage and current sensor apparatus coupled to said system;
(b) detecting a plurality of system faults by self-contained instructional codes contained in respective first and second computer apparatus coupled to and adapted to control the source side converter and said load side converter;
(c) effecting a direct type of protective action in response to certain ones of said faults detected by said sensor apparatus;
(d) effecting first and second types of computer apparatus assisted protective action in response to certain others of said faults detected by said sensor apparatus;
and
(e) effecting said first and second types of computer apparatus assisted protective action in response to said faults detected by said computer apparatus.

3 more elements

A protective system for a power conversion system adapted to drive an AC synchronous motor and including an AC to DC source side thyristor converter coupled from an AC source to a DC to AC load side thyristor converter via a DC link circuit, comprising:

(a) voltage and current sensor means for detecting a plurality of system faults;
(b) source side computer means and load side computer means for detecting a plurality of system faults and for respectively controlling the source side converter and the load side converter;
(c) a memory and intercommunication means coupled between said computer means whereby faults detected by either computer means is communicated with the other computer means to effect a coordinated protective action;
(d) means for providing a direct type of protective action in response to at least one of said faults detected by said sensor means;
(e) stored instructional code means in both said computer means for providing first and second types of protective action in response to other faults of said plurality of faults detected by said sensor means;
and
(f) stored instructional code means in both said computer means for providing said first and second types of protective action in response to said plurality of faults detected by said computer means.

4 more elements

A system for protecting a power conversion system coupled to an AC load and including an AC to DC source side converter coupled from an AC source to a DC to AC load side converter via a DC link circuit and comprising:

(a) means for detecting a plurality of system faults and including selectively located voltage and current sensor means coupled to said system;
(b) means for detecting a plurality of system faults and including a plurality of self-contained instructional codes contained in respective first and second computer means coupled to and adapted to control the source side converter and said load side converter;
(c) means for effecting a direct type of protective action in response to certain ones of said faults detected by said sensor means;
(d) said instructional codes being operable to provide first and second types of computer means assisted protective action in response to certain others of said faults detected by said sensor means;
and
(e) said instructional codes being further operable to provide said first and second types of computer means assisted protective action in response to said faults detected by said computer means.

3 more elements

Dependencies are inferred from the claim text.

Coordinated load commutated inverter protection system

Life of this patent

Coordinated load commutated inverter protection system

Life of this patent

Abstract

Claims38