Electrical system
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.
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 .