US-12617538-B2 - Electrical system

US12617538B2US 12617538 B2US12617538 B2US 12617538B2US-12617538-B2

Abstract

An electrical system includes: a battery; a fuel-cell pack; a load electrically coupled to the fuel-cell pack; a switching arrangement electrically coupled to the battery, the fuel-cell pack and the load; a DC-DC converter; and a control system. The switching arrangement configures the electrical system in at least one of a battery-charge mode and a combined-drive mode. In the battery-charge mode the battery is coupled in series to the fuel-cell pack and the load via the DC-DC converter for simultaneous charging of the battery and driving of the load by the fuel-cell pack. In the combined-drive mode, the battery is coupled in series to the fuel-cell pack and the load via the DC-DC converter for driving of the load by both the battery and the fuel-cell pack. The control system is configured to: monitor a parameter of an electrical power provided to the load; and control the DC-DC converter.

Inventors

Chandana J GAJANAYAKE
Devinda A Molligoda

Assignees

ROLLS-ROYCE PLC

Dates

Publication Date: 20260505
Application Date: 20240523
Priority Date: 20230619

Claims (17)

1 . An electrical system comprising: a battery; a fuel-cell pack; a load electrically coupled to the fuel-cell pack; a switching arrangement electrically coupled to the battery, the fuel-cell pack and the load; a DC-DC converter; and a control system; wherein the switching arrangement is operable to selectively configure the electrical system in at least one of a battery-charge mode and a combined-drive mode; in the battery-charge mode the battery is coupled electrically in series between the fuel-cell pack and the load via the DC-DC converter for simultaneous charging of the battery and driving of the load by the fuel-cell pack; in the combined-drive mode the battery is coupled electrically in series between the fuel-cell pack and the load via the DC-DC converter for driving of the load by both the battery and the fuel-cell pack; and the control system is configured to: monitor a parameter of an electrical power provided to the load; control the DC-DC converter based on the monitored parameter of the electrical power provided to the load and wherein the switching arrangement is operable to selectively configure the electrical system in each of: the battery-charge mode; and the combined-drive mode; and the control system is configured to operate the switching arrangement to selectively reconfigure the electrical system between the battery-charge mode and the combined-drive mode.
2 . The electrical system of claim 1 , wherein the monitored parameter of the electrical power provided to the load is a voltage across the load or a current through the load.
3 . The electrical system of claim 2 , wherein the control system is configured to: control the DC-DC converter to target maintaining the monitored voltage across the load at a target load voltage.
4 . The electrical system of claim 1 , wherein the control system is configured to: monitor a parameter of an electrical power provided by the fuel-cell pack; and operate the switching arrangement to selectively reconfigure the electrical system between the battery-charge mode and the combined-drive mode based on the monitored parameter of the electrical power provided by the fuel-cell pack.
5 . The electrical system of claim 4 , wherein the control system is configured to operate the switching arrangement to selectively reconfigure the electrical system in: the battery-charge mode in response to a determination that the monitored parameter is in a first range indicative of a power demand of the load being relatively low; and the combined-drive mode in response to a determination that the monitored parameter is in a second range indicative of the power demand of the load being relatively high.
6 . The electrical system of claim 5 , wherein a threshold separating the first range and the second range is determined based on a state-of-charge of the battery.
7 . The electrical system of claim 1 , wherein the switching arrangement is operable to selectively configure the electrical system in each of: the battery-charge mode; the combined-drive mode; and a battery-isolation mode in which: the battery is decoupled from the fuel-cell pack and the load, and the fuel-cell pack is coupled to the load for driving of the load by the fuel-cell pack; and the control system is configured to operate the switching arrangement to selectively reconfigure the electrical system between the battery-charge mode, the combined-drive mode and the battery-isolation mode.
8 . The electrical system of claim 7 , wherein the control system is configured to: operate the switching arrangement to selectively reconfigure the electrical system between the battery-charge mode, the combined-drive mode and the battery-isolation mode based on the monitored parameter of the electrical power provided by the fuel-cell pack.
9 . The electrical system of claim 8 , wherein the control system is configured to operate the switching arrangement to selectively reconfigure the electrical system in: the battery-charge mode in response to a determination that the monitored parameter is in a first range indicative of a power demand of the load being relatively low; the combined-drive mode in response to a determination that the monitored parameter is in a second range indicative of the power demand of the load being relatively high; and the battery-isolation mode in response to a determination that the monitored parameter is in an intermediate range defined between the first range and the second range.
10 . The electrical system of claim 9 , wherein at least one of a first threshold and a second threshold respectively separating the first range and the second range from the intermediate range is determined based on a state-of-charge of the battery.
11 . The electrical system of claim 1 , wherein the control system is configured to: when the electrical system is configured in the battery-charge mode, control the DC-DC converter to target maintaining the monitored voltage across the load at a target load voltage; and when the electrical system is configured in the combined-drive mode, control the DC-DC converter to target maintaining the monitored voltage across the load at a target load voltage.
12 . The electrical system of claim 11 , wherein the load is associated with a design operating voltage range defined by a lower design operating voltage and an upper design operating voltage; and the target load voltage is between the lower design operating voltage and the upper design operating voltage.
13 . The electrical system of claim 1 , wherein the control system is further configured to: monitor a voltage across the load; monitor a voltage across the fuel-cell pack; and vary a reactant flow rate, a cell pressure and/or a cell temperature of the fuel-cell pack to maintain the monitored voltage across the fuel-cell pack as being equal to the monitored voltage across the load.
14 . The electrical system of claim 1 , wherein the control system is further configured to: monitor a current through the load; monitor a current through the fuel-cell pack; and vary a reactant flow rate, a cell pressure and/or a cell temperature of the fuel-cell pack to maintain the monitored voltage through the fuel-cell pack as being equal to the monitored current through the load.
15 . The electrical system of claim 1 , wherein the load is associated with a design operating voltage; and the battery has a peak output voltage of no greater than 60% of the design operating voltage of the load.
16 . The electrical system of claim 1 , wherein the switching arrangement includes: a first pair of switching devices coupled in series through a first junction, and a second pair of switching devices coupled in series through a second junction; the first pair of switching devices and the second pair of switching devices are coupled in parallel with each other with respect to a pair of battery connection terminals; the fuel-cell pack and the load are coupled to or couplable to the switching arrangement at the first junction and the second junction; and the battery is coupled to or couplable to the switching arrangement at the pair of battery connection terminals.
17 . An aircraft comprising the electrical system of claim 1 .

Description

This specification is based upon and claims the benefit of priority from UK Patent Application Number 2309170.5 filed on 19 Jun. 2023, the entire contents of which are incorporated herein by reference. BACKGROUND Technical Field of the Disclosure This disclosure concerns an electrical system comprising: a battery; a fuel-cell pack; a load electrically coupled to the fuel cell a switching arrangement electrically coupled to the battery, the fuel-cell pack and the load; a DC-DC converter; and a control system. The disclosure further concerns an aircraft comprising such an electrical system. Background of the Disclosure In view of current industrial trends and objectives, it is desirable to incorporate a greater degree of electrical functionality on an aircraft airframe and/or on propulsive device such as a gas turbine engine. In particular, it is desirable to provide an electrical system which is able to meet a power demand of a load (e.g., a propulsive device of an aircraft) across a broad range of operating scenarios. U.S. Pat. No. 7,557,532 B2 describes a voltage supplying apparatus comprising a fuel cell, a DC-DC voltage converter and a control circuit. The DC-DC voltage converter is used to receive a voltage outputted from the fuel cell and then to output another voltage. Then, the respective voltages outputted from the fuel cell and the DC-DC voltage converter are combined to be an output voltage of the voltage supplying apparatus. The control circuit is used to control operation of the DC-DC voltage converter according to a magnitude of the output voltage of the voltage supplying apparatus. U.S. Pat. No. 10,483,573 B2 describes a fuel cell unit comprising a fuel cell and a regulating voltage converter, and further describes a fuel cell module comprising a plurality of fuel cell units connected in parallel. SUMMARY According to a first aspect there is provided an electrical system comprising: a battery; a fuel-cell pack; a load electrically coupled to the fuel-cell pack; a switching arrangement electrically coupled to the battery, the fuel-cell pack and the load; a DC-DC converter; and a control system; wherein the switching arrangement is operable to selectively configure the electrical system in at least one of a battery-charge mode and a combined-drive mode; wherein in the battery-charge mode the battery is coupled in series to the fuel-cell pack and the load via the DC-DC converter for simultaneous charging of the battery and driving of the load by the fuel-cell pack; wherein in the combined-drive mode the battery is coupled in series to the fuel-cell pack and the load via the DC-DC converter for driving of the load by both the battery and the fuel-cell pack; and wherein the control system is configured to: monitor a parameter of an electrical power provided to the load; and control the DC-DC converter based on the monitored parameter of the electrical power provided to the load. It may be that the monitored parameter of the electrical power provided to the load is a voltage across the load or a current through the load. The control system is configured to control the DC-DC converter to target maintaining the monitored voltage across the load at a target load voltage. It may be that the switching arrangement is operable to selectively configure the electrical system in each of: the battery-charge mode; and the combined-drive mode. It may also be that the control system is configured to operate the switching arrangement to selectively reconfigure the electrical system between the battery-charge mode and the combined-drive mode. The control system may be configured to: monitor a parameter of an electrical power provided by the fuel-cell pack; and operate the switching arrangement to selectively reconfigure the electrical system between the battery-charge mode and the combined-drive mode based on the monitored parameter of the electrical power provided by the fuel-cell pack. It may be that: when the electrical system is in the battery-charge mode, a polarity of the battery is in a first orientation with respect to a polarity of the fuel-cell pack; and when the electrical system is in the combined-drive mode, the polarity of the battery is in a second orientation with respect to the polarity of the fuel-cell pack, and wherein the second orientation opposes the first orientation. Further, it may be that the control system is configured to operate the switching arrangement to selectively reconfigure the electrical system in: the battery-charge mode in response to a determination that the monitored parameter is in a first range indicative of a power demand of the load being relatively low; and the combined-drive mode in response to a determination that the monitored parameter is in a second range indicative of the power demand of the load being relatively high. The first and second ranges may be contiguous and separated by a single threshold. At least one threshold, or a plurality of thresholds, separating