Electrical systems

Abstract

Electrical systems for connecting rotary electric machines with gas turbine spools are provided. One such electrical system comprises: a first dual-wound rotary electric machine mechanically coupled with a first gas turbine spool and comprising a first three-phase sub-machine and a second three-phase submachine; a second dual-wound rotary electric machine mechanically coupled with a second gas turbine spool and comprising a third three-phase sub-machine and a fourth three-phase submachine; and a set of N=4 bidirectional converter circuits for conversion of alternating current (ac) to and from direct current (dc), each of which has an associated index n=(1, . . . , N), and for all n, the ac side of the nth bidirectional converter circuit is connected with the nth three-phase sub-machine. The dc side of the first converter circuit is connected with the dc side of the third converter circuit, and the dc side of the second converter circuit is connected with the dc side of the fourth converter circuit.

1 . An electrical system for connecting rotary electric machines with gas turbine spools, further comprising:
 a first dual-wound rotary electric machine mechanically coupled with a first gas turbine spool and comprising a first three-phase sub-machine and a second three-phase submachine;   a second dual-wound rotary electric machine mechanically coupled with a second gas turbine spool and comprising a third three-phase sub-machine and a fourth three-phase submachine;   a set of N=4 bidirectional converter circuits for conversion of alternating current (ac) to and from direct current (dc), each of which has an associated index n=(1, . . . , N), and for all n, the ac side of the nth bidirectional converter circuit is connected with the nth three-phase sub-machine; and   the dc side of the first converter circuit is connected with the dc side of the third converter circuit, and the dc side of the second converter circuit is connected with the dc side of the fourth converter circuit.   
     
     
         2 . The electrical system of  claim 1 , in which:
 the dc side of the first converter circuit and the dc side of the third bidirectional converter circuit are connected to a first dc output bus; and   the dc side of the second converter circuit and the dc side of the fourth bidirectional converter circuit are connected to a second dc output bus.   
     
     
         3 . The electrical system of  claim 2 , in which the connection to the first dc output bus is via a first switch array, and the connection to the second dc output bus is via a second switch array. 
     
     
         4 . The electrical system of  claim 3 , in which the first switch array and the second switch array each comprise:
 a first input connected with one of the converter circuits;   a second input connected with another one of the converter circuits;   an output connected with one of the dc output busses;   a first switch between the first input and the output;   a second switch between the second input and the output;   a bus tie across the first input and the second input, the bus tie comprising a third switch.   
     
     
         5 . The electrical system of  claim 4 , in which the first switch array and the second switch array are configured to operate in a no-fault condition in which the first switch and the second switch are closed, and the third switch is opened. 
     
     
         6 . The electrical system of  claim 4 , in which the first switch array and the second switch array are configured to operate in a first fault condition in which the second switch is closed, and the first switch and the third switch are opened. 
     
     
         7 . The electrical system of  claim 6 , further comprising a control circuit configured to:
 operate the first switch array in the first fault condition in response to identification of a fault between the first three-phase submachine and the first converter circuit; and   operate the second switch array in the first fault condition in response to identification of a fault between the second three-phase submachine and the second converter circuit.   
     
     
         8 . The electrical system of  claim 4 , in which the first switch array and the second switch array are configured to operate in a second fault condition in which the first switch is closed, and the second switch and the third switch are opened. 
     
     
         9 . The electrical system of  claim 8 , further comprising a control circuit configured to:
 operate the first switch array in the second fault condition in response to identification of a fault between the third three-phase submachine and the third converter circuit; and   operate the second switch array in the second fault condition in response to identification of a fault between the fourth three-phase submachine and the fourth converter circuit.   
     
     
         10 . The electrical system of  claim 4 , in which the first switch array and the second switch array are configured to operate in a third fault condition in which the third switch is closed, and the first switch and the second switch are opened. 
     
     
         11 . The electrical system of  claim 10 , further comprising a control circuit configured to:
 operate the first switch array in the third fault condition in response to identification of a fault between the output of the first switch array and the first dc output bus; and   operate the second switch array in the third fault condition in response to identification of a fault between the output of the second switch array and the second dc output bus.   
     
     
         12 . The electrical system of  claim 4 , in which the switches are dc contactors. 
     
     
         13 . A gas turbine engine having a low-pressure spool and a high-pressure spool, and further comprising the electrical system of  claim 1 , in which the first gas turbine spool is the low-pressure spool and the second gas turbine spool is the high-pressure spool. 
     
     
         14 . An arrangement comprising:
 a first gas turbine engine having a first spool;   a second gas turbine engine different from the first gas turbine engine, and having a second spool; and   the electrical system of  claim 1 , in which the first gas turbine spool is the first spool of the first gas turbine engine, and the second gas turbine spool is the second spool of the second gas turbine engine.   
     
     
         15 . An aircraft comprising the gas turbine of  claim 13 . 
     
     
         16 . An aircraft comprising the arrangement of  claim 14 .