US 12,326,109 B2
Electrical power system converter control
Francisco Javier Chivite Zabalza, Stafford (GB); David R Trainer, Derby (GB); Mark Sweet, Chesterfield (GB); Matthew C Morris, Glasgow (GB); Zafer Jarrah, Bristol (GB); and James A Campbell, Nottingham (GB)
Assigned to ROLLS-ROYCE plc, London (GB)
Filed by ROLLS-ROYCE plc, London (GB)
Filed on Sep. 22, 2022, as Appl. No. 17/950,423.
Claims priority of application No. 2115016 (GB), filed on Oct. 20, 2021.
Prior Publication US 2023/0124932 A1, Apr. 20, 2023
Int. Cl. F02C 6/00 (2006.01); B64D 27/10 (2006.01); B64D 27/24 (2006.01); H02J 3/02 (2006.01); H02M 1/00 (2006.01); H02M 1/12 (2006.01); H02M 5/458 (2006.01); H02M 7/219 (2006.01); B64D 27/02 (2006.01)
CPC F02C 6/00 (2013.01) [B64D 27/10 (2013.01); B64D 27/24 (2013.01); H02J 3/02 (2013.01); H02M 1/0058 (2021.05); H02M 1/12 (2013.01); H02M 5/4585 (2013.01); H02M 7/219 (2013.01); B64D 27/026 (2024.01); B64D 2221/00 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An electrical power system comprising:
an electrical machine operable to output AC;
a DC electrical network;
a power electronics converter connected between the AC output of the electrical machine and the DC electrical network and comprising, for each phase of the AC output, a phase leg comprising a first branch having a first bi-directional MOSFET and a second branch having a second bi-directional MOSFET; and
a controller configured to control switching of the first and second bi-directional MOSFETs of each phase leg of the converter so that, during normal operation of the electrical power system, current is commutated between the first and second branches of the phase leg to rectify the AC input to DC to supply the DC electrical network with DC electrical power, wherein
the controller is further configured, responsive to a determination to the effect that there is a fault in the DC electrical network, to control the switching of the first and second bi-directional MOSFETs of each phase leg to switch the converter into a crow-bar configuration in which current from the electrical machine does not flow to the DC network,
the first branch further includes a first diode in parallel with the first bi-directional MOSFET and the second branch further includes a second diode in parallel with the second bi-directional MOSFET, and
the electrical machine and converter satisfy the inequality VF/RDS-ON>IFAULT, MAX, where
VF is a forward voltage drop of the first diode,
RDS-ON is an on-state resistance of the second MOSFET, and
IFAULT, MAX is a maximum rated current outputtable by the electrical machine when there is zero voltage across its terminals.
 
14. A method of operating an electrical power system comprising an electrical machine operable to output AC, a DC electrical network and a power electronics converter connected between the AC output of the electrical machine and the DC electrical network,
the power electronics converter comprising, for each phase of the output AC, a phase leg comprising a first branch including a first bi-directional MOSFET and a second branch including a second bi-directional MOSFET;
the method comprising:
in a first mode of operation corresponding to normal operation of the electrical power system, controlling switching of the first and second bi-directional MOSFETs of each phase leg so that current is commutated between the first and second branches of the phase leg to rectify the AC input to DC to supply the DC electrical network with DC electrical power; and
in a second mode of operation corresponding to operation with a fault in the DC electrical network, controlling switching of the of the first and second MOSFETs of each phase leg to switch the converter into a crow-bar configuration in which current from the electrical machine does not flow to the DC network, wherein
in the second mode of operation, the switching of the first and second bi-directional MOSFETs of each phase leg is controlled so that current flowing through the first branch of the phase leg is conducted through the first bi-directional MOSFET in a first direction and current flowing through the second branch of the phase leg is conducted through the second bi-directional MOSFET in a second direction opposite to the first direction.