Electrical power systems
Electrical power systems for distributing electrical power in aircraft are described. One such electrical power system comprises: an electrical power source configured to output a number R≥2 of dc power channels, each dc power channel having a respective index r=(1, . . . , R); and a group of N dc load channels connected to the R dc power channels by a switching arrangement, wherein each dc load channel has a respective index n=(1, . . . , N) and R<N≤2R. The switching arrangement is operable to connect the r-th power channel to the n-th load channel according to a relationship r(n).
1. An electrical power system for distributing electrical power in an aircraft, the electrical power system comprising:
an electrical power source configured to output a number R≥2 of dc power channels, each dc power channel having a respective index r=(1, . . . , R); and
a group of N dc load channels connected to the R dc power channels by a switching arrangement, wherein
each dc load channel has a respective index n=(1, . . . , N) and R<N≤2R, and
the switching arrangement is operable to connect an r-th dc power channel to an n-th dc load channel according to the relationship:
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2. The electrical power system of claim 1 , wherein the electrical power source comprises one or more batteries.
3. The electrical power system of claim 1 , wherein N=2R.
4. The electrical power system of claim 1 , wherein R=2, 3 or 4.
5. The electrical power system of claim 1 , wherein N≥4.
6. The electrical power system of claim 1 , further comprising:
a controller configured to control operation of the switching arrangement.
7. The electrical power system of claim 6 , wherein the controller is configured to control the operation of the switching arrangement so that, at all times, each one of N-2 load channels for which 1<n<N receives power from only one of two power channels to which it can be connected by the switching arrangement.
8. The electrical power system of claim 1 , wherein, in a no fault condition, each one of N-2 load channels for which 1<n<N receives power from both of two power channels to which it is connected by the switching arrangement.
9. The electrical power system of claim 1 , comprising:
a controller configured to control operation of the switching arrangement so that, in a fault condition in which one of the R power channels has a fault, each one of the respective N-2 load channels for which 1<n<N receives power from a non-faulted power channel of two power channels to which the respective load channel can be connected by the switching arrangement.
10. The electrical power system of claim 1 , comprising:
a controller configured to control operation of the switching arrangement so that, at all times, each one of the R power channels delivers electrical power to a number of load channels not exceeding ┌N/R┐1+1.
11. The electrical power system of claim 1 , comprising:
a controller configured to control operation of the switching arrangement so that, in a no fault condition, each one of the R power channels delivers electrical power to a number of load channels not exceeding ┌N/R┐.
12. The electrical power system of claim 1 , comprising:
a controller configured to control operation of the switching arrangement so that, in a fault condition in which one of the R power channels has a fault, each one of the R power channels delivers electrical power to a number of load channels not exceeding ┌N/R┐+1.
13. The electrical power system of claim 1 , comprising:
a controller, wherein
the N dc load channels are connected to and power a poly-phase electrical load, and
the controller is configured to control the switching arrangement so that, in a no fault condition, pairs of phases of the poly-phase electrical load are powered by the same power channels so as to cancel harmonics in current supplied by the power channels.
14. The electrical power system of claim 13 , wherein the phases of each pair of phases are electrically separated by 360/P degrees, P being a total number of phases of the poly-phase electrical load.
15. The electrical power system of claim 1 , wherein the N load channels are connected to one or more loads including at least one propulsive load.
16. The electrical power system of claim 15 , wherein the at least one propulsive load comprises an electric machine comprising at least two submachines.
17. The electrical power system of claim 1 , wherein, for each respective load channel of a plurality of N load channels, the switching arrangement includes or is connected to a current limiting device (CLD) operable to limit an amount of current flowing from the power channels to a load connected to the electrical power system via the respective load channel.
18. An aircraft propulsion system comprising:
the electrical power system of claim 1 .
19. The aircraft propulsion system of claim 18 , comprising:
one or more propulsors, wherein
the R power channels of the electrical power system are arranged to deliver power to the one or more propulsors, and
the N load channels are electrically connected to one or more non-propulsive loads.
20. An aircraft comprising:
the electrical power system of claim 1 .