ENERGY SYSTEM CONTROL

Abstract

The disclosure concerns a controller arranged to control an energy system where the energy system comprises one or more first energy operators and one or more second energy operators, an energy storing system and an energy storing system monitoring device. The controller is arranged to have control over variation in operation of the one or more first energy operators and variation in operation of the second energy operators is at least partially beyond the control of the controller. At least one of the energy operators is an energy supply system and at least one and the remainder of the energy operators are energy consuming systems. At least two of the energy operators are variable energy operators. Where an energy supply system is a variable energy operator, variation in operation of that energy supply system adjusts the energy it supplies. Where an energy consuming system is a variable energy operator, variation in operation of that energy consuming system adjusts the energy it consumes. Outputs of the energy supply systems, inputs of the energy consuming systems and a connection of the energy storing system are connected by a common connection such that they are maintained at the same potential. The energy storing system is arranged to provide energy to the common connection to compensate where there is a deficit in energy supplied by the at least one energy supply system as compared with the energy demand from the at least one energy consuming system. The controller comprises an input arranged to receive a data signal indicative of the power output of the energy storing system from the energy storing system monitoring device; a processing system arranged to determine, in accordance with the energy storing system power output data received, whether and to what extent there is a deficit which exceeds an energy storing system discharging set point value, and where there is, a variation in control for at least one of the first energy operators corresponding in magnitude to the determined extent of the deficit to compensate and return the deficit to the energy storing system discharging set point value; and an output via which the processing system sends one or more control signals to control the at least one of the first energy operators accordingly.

Claims

1. A controller arranged to control an energy system where the energy system comprises one or more first energy operators and one or more second energy operators, an energy storing system and an energy storing system monitoring device, where the controller is arranged to have control over variation in operation of the one or more first energy operators and variation in operation of the second energy operators is at least partially beyond the control of the controller, and where at least one of the energy operators is an energy supply system and at least one and the remainder of the energy operators are energy consuming systems, and where further at least two of the energy operators are variable energy operators, and where an energy supply system is a variable energy operator, variation in operation of that energy supply system adjusts the energy it supplies, and where an energy consuming system is a variable energy operator, variation in operation of that energy consuming system adjusts the energy it consumes, and where outputs of the energy supply systems, inputs of the energy consuming systems and a connection of the energy storing system are connected by a common connection such that they are maintained at the same potential, and where further the energy storing system is arranged to provide energy to the common connection to compensate where there is a deficit in energy supplied by the at least one energy supply system as compared with the energy demand from the at least one energy consuming system, and where the controller comprises: an input arranged to receive a data signal indicative of the power output of the energy storing system from the energy storing system monitoring device; a processing system arranged to determine, in accordance with the energy storing system power output data received, whether and to what extent there is a deficit which exceeds an energy storing system discharging set point value, and where there is, a variation in control for at least one of the first energy operators corresponding in magnitude to the determined extent of the deficit to compensate and return the deficit to the energy storing system discharging set point value; and an output via which the processing system sends one or more control signals to control the at least one of the first energy operators accordingly.

2. A controller according to claim 1 where the energy storing system discharging set point value is set at a level at which there is substantially zero energy storing system discharging.

3. A controller according to claim 1 where the energy storing system discharging set point value is set at a level at which there is discharging of the energy storing system.

4. A controller according to claim 1 where the controller is arranged to dynamically vary the energy storing system discharging set point value.

5. A controller according to claim 1 where the controller is arranged to dynamically vary the energy storing system discharging set point value to temporarily over compensate for a deficit to an extent sufficient to return the energy storing system substantially to its state of charge prior to the commencement of the deficit.

6. A controller according to claim 1 where the energy storing system is arranged to be charged using excess energy from the common connection to compensate where there is a surplus in energy supplied by the at least one energy supply system as compared with the energy demand from the at least one energy consuming system.

7. A controller according to claim 6 where the processing system is arranged to determine, in accordance with the energy storing system power output data received, whether and to what extent there is a surplus which exceeds an energy storing system charging set point value, and where there is, a variation in control for at least one of the first energy operators corresponding in magnitude to the determined extent of the deficit to compensate and return the surplus to the energy storing system charging set point value and send one or more control signals to control the at least one of the first energy operators accordingly.

8. A controller according to claim 7 where the energy storing system charging set point value is set at a level at which there is substantially zero energy storing system charging.

9. A controller according to claim 7 where the energy storing system charging set point value is set at a level at which there is charging of the energy storing system.

10. A controller according to claim 7 where the controller is arranged to dynamically vary the energy storing system charging set point value.

11. A controller according to claim 7 where the controller is arranged to dynamically vary the energy storing system charging set point value to temporarily over compensate for a surplus to an extent sufficient to return the energy storing system substantially to its state of charge prior to the surplus.

12. A controller according to claim 1 where the controller is arranged to monitor the energy storing system power output and perform compensatory control of the at least one of the first energy operators dependent on the power output of the energy storing system in real-time.

13. A controller according to claim 1 where compensatory control of the at least one of the first energy operators dependent on the power output of the energy storing system is applied as a correction to control dependent on a model of anticipated energy supply and/or energy consumption of the energy supply system.

14. A controller according to claim 1 where the energy system is an electrical energy system.

15. A controller according to claim 1 where the energy system is arranged such that a current flowing on the common connection is direct current.

16. A controller according to claim 1 where the energy storing system comprises a battery.

17. A controller according to claim 1 where the first energy operators are selected from among a fuel cell, an electrolyser, an internal combustion engine, a battery, a capacitor.

18. A controller according to claim 1 where the second energy operators are selected from among an intermittent renewable energy source, an energy distribution network, a vehicle motor, commercial equipment and a domestic appliance.

19. (canceled)

20. An energy system comprising one or more first energy operators and one or more second energy operators, an energy storing system, an energy storing system monitoring device and a controller, where the controller is arranged to have control over variation in operation of the one or more first energy operators and variation in operation of the second energy operators is at least partially beyond the control of the controller, and where at least one of the energy operators is an energy supply system and at least one and the remainder of the energy operators are energy consuming systems, and where further at least two of the energy operators are variable energy operators, and where an energy supply system is a variable energy operator, variation in operation of that energy supply system adjusts the energy it supplies, and where an energy consuming system is a variable energy operator, variation in operation of that energy consuming system adjusts the energy it consumes, and where outputs of the energy supply systems, inputs of the energy consuming systems and a connection of the energy storing system are connected by a common connection such that they are maintained at the same potential, and where further the energy storing system is arranged to provide energy to the common connection to compensate where there is a deficit in energy supplied by the at least one energy supply system as compared with the energy demand from the at least one energy consuming system, and where the controller comprises: an input arranged to receive a data signal indicative of the power output of the energy storing system from the energy storing system monitoring device; a processing system arranged to determine, in accordance with the energy storing system power output data received, whether and to what extent there is a deficit which exceeds an energy storing system discharging set point value, and where there is, a variation in control for at least one of the first energy operators corresponding in magnitude to the determined extent of the deficit to compensate and return the deficit to the energy storing system discharging set point value; and an output via which the processing system sends one or more control signals to control the at least one of the first energy operators accordingly.

21. A method of controlling an energy system, where the energy system comprises one or more first energy operators and one or more second energy operators and an energy storing system and where variation in operation of the one or more first energy operators is controllable according to the method while variation in operation of the second energy operators is at least partially beyond the control of the method, and where at least one of the energy operators is an energy supply system and at least one and the remainder of the energy operators are energy consuming systems, and where further at least two of the energy operators are variable energy operators, and where an energy supply system is a variable energy operator, variation in operation of that energy supply system adjusts the energy it supplies, and where an energy consuming system is a variable energy operator, variation in operation of that energy consuming system adjusts the energy it consumes, and where outputs of the energy supply systems, inputs of the energy consuming systems and a connection of the energy storing system are connected by a common connection such that they are maintained at the same potential, and where further the energy storing system is arranged to provide energy to the common connection to compensate where there is a deficit in energy supplied by the at least one energy supply system as compared with the energy demand from the at least one energy consuming system, the method comprising: receiving data indicative of the power output of the energy storing system; determining, in accordance with the energy storing system power output data received, whether and to what extent there is a deficit which exceeds an energy storing system discharging set point value, and where there is, a variation in control for at least one of the first energy operators corresponding in magnitude to the determined extent of the deficit to compensate and return the deficit to the energy storing system discharging set point value; and controlling the at least one of the first energy operators accordingly.

22.-24. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] One or more embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

[0059] FIG. 1 is a schematic representation of a controller according to an embodiment of the invention;

[0060] FIG. 2 is a schematic representation of an energy system according to an embodiment of the invention;

[0061] FIG. 3 is a schematic representation of an energy system according to an embodiment of the invention;

[0062] FIG. 4a is graph showing total energy generated and total energy demanded over a period by the energy system of FIG. 3;

[0063] FIG. 4b is a graph showing surplus and deficit of generated energy in accordance with the total energy generated and total energy demanded as shown in FIG. 4a;

[0064] FIG. 5 is a graph showing various performance characteristics for the energy system of FIG. 3 operating in accordance with the FIGS. 4a and 4b scenario;

[0065] FIG. 6 is a schematic representation of an energy system according to an embodiment of the invention; and

[0066] FIG. 7 is a schematic representation of a controller according to an embodiment of the invention.

DETAILED DESCRIPTION

[0067] Referring first to FIGS. 2 and 3, an energy system is generally provided at 1. In this case the energy system 1 is an electrical energy system and has a number of energy operators 3, a common connection (in this case a busbar 5) and an energy storing system (in this case a battery 7).

[0068] Among the energy operators 3 are those which are energy supply systems 9 (in this case a renewable energy source 11 and a hydrogen fuel cell 13) and those which are energy consuming systems 15 (in this case an electrical demand 17 and an electrolyser 19). In this case, all of the energy operators 3 are variable energy operators, in that the electrical energy which they supply (in the case of energy supply systems 9) and consume (in the case of energy consuming systems 15) in a given time period is variable. Nonetheless, in other embodiments it will be appreciated that one or more of the energy operators 3 may be arranged to supply/demand a fixed quantity of electrical energy in a given time period. Some (first energy operators 21) of the energy operators 3, are controllable by an energy system controller 23 (see FIGS. 1 and 3) to vary, in the case of energy supply systems, their supply and, in the case of energy consuming systems, consumption, of electrical energy in a given time period. The first energy operators 21 are the hydrogen fuel cell 13 and the electrolyser 19. The remainder (second energy operators 25) of the energy operators 3, are not controllable by the energy system controller 23 (nor indeed the energy 1 system itself) to vary their supply/consumption of electrical energy in a given time period. The second energy operators 25 are the renewable energy source 11 and electrical demand 17. In the case of the renewable energy source 11 of the present embodiment, the variation in the energy supplied is driven by weather changes, and in the case of the electrical demand 17, the variation in the consumption is driven by end user usage.

[0069] Respective electrical energy outputs of the renewable energy source 11 and hydrogen fuel cell 13 are electrically connected to the busbar 5. Respective electrical energy inputs of the electrical demand 17 and electrolyser 19 are electrically connected to the busbar 5. Finally, an electrical energy connection of the battery 7 is connected to the busbar 5. In use direct current flows through the busbar 5.

[0070] A hydrogen gas tank 27 is also provided with hydrogen supply lines 29 from the electrolyser 19 and to the fuel cell 13.

[0071] An energy storing system monitoring device (in this case a current sensor (not shown)) is also provided, which detects the current flow from the battery 7.

[0072] Referring to FIGS. 1 and 3, the controller 23 has a processor 31, a memory 33, a battery current input 35, a generation modeller input 37, a demand modeller input 39, a tank status input 41, a fuel cell control output 43 and an electrolyser control output 45. The memory 33 is in communication with the processor 31 and stores firmware, software and data for operating the controller 23. The battery current input 35 is arranged to receive data signals from the current sensor indicative of the power output of the battery 7 (in this case the current passing through the battery 7) from the current sensor. The generation modeller input 37 is arranged to receive data signals from an energy generation modeller 47 indicative of predicted energy generation over a given period by the renewable energy source 11. The demand modeller input 39 is arranged to receive data signals from an energy demand modeller 49 indicative of predicted energy demand over the given period by the electrical demand 17. The tank status input 41 is arranged to receive data signals from a pressure sensor (not shown) provided in the hydrogen gas tank 27, indicative of its remaining supply of hydrogen gas. The fuel cell control output 43 is connected to a data input of a fuel cell control module 51 and is arranged to send control signals to vary the control of the fuel cell 13. The electrolyser control output 45 is connected to a data input of an electrolyser control module 53 and is arranged to send control signals to vary the control of the electrolyser 19. The processor 31 is arranged to perform processing operations in accordance with programming.

[0073] In use, the energy system 1 generates and supplies electrical energy to the electrical demand 17. Electrical energy to supply the demand 17 is principally generated by the renewable energy source 11, which supplies power to the busbar 5 via its electrical energy output. Electrical energy is delivered from the busbar 5 to the electrical demand 17 via the electrical energy input of electrical demand 17. Nonetheless the electrical energy generated by the renewable energy source 11 is variable in a manner not controllable by the controller 23 nor indeed the wider energy system 1, being subject to the vagaries of the weather. Similarly, so long as it is sufficiently supplied, the consumption of the electrical demand 17 is also variable in a manner not controllable by the controller 23 nor indeed the wider energy system 1, being subject to the vagaries of user demand.

[0074] In order that the demands of the electrical demand 17 can be met even where at a particular time there is a deficit in electrical energy generation by the renewable energy source 11 by comparison with that demand, the hydrogen fuel cell 13 is provided to make up the deficit by generating electrical energy using hydrogen stored in the hydrogen gas tank 27. Similarly, in order that any surplus in electrical energy generated by the renewable energy source 11 by comparison with the demand of the electrical demand 17 at a particular time is not wasted, the electrolyser 19 is provided to store the energy chemically by converting it to hydrogen and storing it in the hydrogen gas tank 27.

[0075] As will be appreciated, in response to a change in the rate of electrical energy supply from the renewable energy source 11 and/or a change in the rate of electrical energy demand from the electrical demand 17, some time is required to adjust operation of the fuel cell 13 and/or electrolyser 19 to compensate. The battery 7 provides this time, by supplying/absorbing electrical energy to maintain the potential on the busbar 5 while the adjustments are made. The battery 7 however also serves as a sensor, its power consumption, positive or negative, indicating the magnitude of the deficit/surplus, and therefore the adjustment required to the fuel cell and/or the electrolyser to compensate.

[0076] The controller 23 controls operation of the energy system 1 as follows. Via its generation modeller input 37, the controller 23 receives updates indicating predicted energy generation over a given time period by the renewable energy source 11 from the energy generation modeller 47. The energy generation modeller 47 itself receives data signals from the renewable energy source 11 indicative of its performance level (e.g. settings and/or maintenance condition) as well as other relevant data for predicting energy generation (in this case weather forecast information and/or measurements of power supplied trend data). The energy generation modeller 47 uses the received data and predicts energy generation for the renewable energy source 11 over the given time period. Via its demand modeller input 39, the controller 23 receives updates indicating predicted energy demand over the given time period of the electrical demand 17 from the energy demand modeller 49. The energy demand modeller 49 itself receives data signals from the electrical demand 17 indicating trend data in terms of its historical demands (e.g. at different times of day, different times of the week and different times of the year) as well as other relevant data for predicting energy demand, e.g. power supplied trend data and/or the likely occurrence of special/unusual events and/or the availability of capacity generated by alternative means. The energy demand modeller 49 uses the received data and predicts energy demand for the electrical demand 17 over the given time period.

[0077] Based on the predicted energy generation for the renewable energy source 11, predicted energy demand for the electrical demand 17 and the quantity of hydrogen gas stored in the hydrogen gas tank 27, the processor 31 of the controller calculates a baseline for control of the fuel cell 13 and electrolyser 19 over the given time period such that if the predictions were correct, the energy system 1 would remain substantially stable in that the demands of the electrical demand 17 are met, that over supply by the renewable energy source 11 is stored in the form of hydrogen gas and that hydrogen gas in the hydrogen gas tank 27 is not completely depleted nor that the capacity of the hydrogen gas tank 27 is reached.

[0078] In real-time throughout the given time period, the controller 23 adjusts the baseline for control of the fuel cell 13 and electrolyser 19 in accordance with the real time power output of the battery 7 as calculated by the processor 31 in accordance with the received data signals from the current sensor and the real time remaining supply of hydrogen gas in the hydrogen gas tank 27. Because the power output of the battery 7 indicates the moment by moment discrepancy between generated and demanded energy for the energy system 1, it can be used to make adjustments to control of the energy generated by the fuel cell 13 and/or the energy absorbed by the electrolyser 19 to bring the contribution of the battery 7 (in terms of provision or absorption of energy) to a desired level. The processor controls the fuel cell 13 and electrolyser 19 accordingly, sending control signals via the fuel cell control output 43 and electrolyser control output 45 respectively.

[0079] As will be appreciated, the baseline for control of the fuel cell 13 and electrolyser 19 may be updated, particularly as new data becomes available. It may be for instance that the baseline is updated continuously e.g. so that it always extends for the pre-determined time period into the future from the current time.

[0080] In the present embodiment, it is desired to maintain, to the extent possible, a mid-level charge state on the battery 7. Therefore, the controller 23 controls the fuel cell 13 and electrolyser 19 accordingly, rapidly adjusting their operation to return the battery 7 to a state where there is substantially zero charging/discharging thereof. That is, in this case, the controller 23 operates the fuel cell 13 and electrolyser 19 so that discharge from the battery 7 is maintained at/returned to an energy storing system discharging set point value which is substantially zero. Similarly, the controller 23 operates the fuel cell 13 and electrolyser 19 so that charging of the battery 7 is maintained at/returned to an energy storing system charging set point value which is substantially zero. Nonetheless, the controller 23 does dynamically adjust the energy storing system discharging set point value and the energy storing system charging set point value to maintain the battery 7 charge at a substantially consistent level and/or in order to manage the hydrogen gas reserves in the hydrogen gas tank 27. Thus, for example, the controller 23 temporarily over compensates for a surplus in energy generation to an extent sufficient to return the battery substantially to its state of charge prior to the surplus.

[0081] Referring now to FIGS. 4a and 4b, an example indication of the performance of the energy system 1 is shown. In FIG. 4a, the traces indicate that for an initial period the energy generated by the renewable energy source 11) is exceeding the energy demanded by the electrical demand 17), and so during this time, the battery 7 will be charged. At least in part through the action of the controller 23 however, the total energy generated is decreased after its initial peak and the total demand is increased. The controller 23 achieves energy balance by adjusting the operation of the fuel cell 13 and electrolyser 19. Thereafter the traces indicate that the controller 23 begins to reverse the charging of the battery that has occurred by temporarily maintaining the total demand at a level above the total energy generated. FIG. 4b indicates the surplus and deficit in energy generated at different times corresponding to the generation and demand traces shown over the same time period in FIG. 4a.

[0082] Referring now to FIG. 5, operation traces associated with various performance parameters of the energy system 1 during the example scenario discussed with regard to FIG. 4 are shown. Trace 61 shows a predicted power to be delivered to the electrolyser 19 over time in accordance with the baseline as determined by the processor 31. Trace 63 shows a predicted power to be supplied by the fuel cell 13 over time in accordance with the baseline as determined by the processor 31. Trace 65 shows the actual power delivered to the electrolyser 19 over time as controlled by the controller 23. Trace 67 shows the actual power supplied by the fuel cell 13 over time as controlled by the controller 23. Traces 69 and 71 show respectively the surplus and deficit in energy generated at different times corresponding to the generation and demand traces shown over the same time period in FIG. 4a. Traces 73 and 75 show respectively the predicted surplus and deficit over time in accordance with the baseline as determined by the processor 31. Trace 77 shows the battery 7 power over time as determined by the controller 23 in accordance with the current sensor data signal. Trace 79 shows a feedback signal of the battery 7 power. The feedback signal consists of a cumulative time series of battery power contributions over time as determined by the controller 23. The length of the time series and the weights of its components are determined and adjusted empirically. Trace 81 is the power output of a boost converter of the fuel cell 13. The boost converter regulates the variable voltage of the fuel cell 13 towards the nominal voltage of the busbar 5 and serves as a control element of the fuel cell power.

[0083] Referring now to FIG. 6 an example of an alternative electric system (in this case for a fuel cell hybrid electric vehicle (FCHEV)) is generally shown at 100. The electric system 100 is similar to the electric system 1 in several ways. The energy system 100 has a number of energy operators 103, a common connection (in this case a busbar 105) and an energy storing system (in this case a battery 107).

[0084] Among the energy operators 103 are an energy supply system 109 (in this case a hydrogen fuel cell 113) and an energy consuming system 115 (in this case a motor of the vehicle 117). In this case, all of the energy operators 103 are variable energy operators, in that the electrical energy which they supply (in the case of the energy supply system 109) and consume (in the case of energy consuming system 115) in a given time period is variable. The fuel cell 113 is a first energy operator 121, controllable by an energy system controller 123 to vary its supply of electrical energy in a given time period. The motor of the vehicle 117 is a second energy operator 125, not controllable by the energy system controller 123 (nor indeed the energy 100 system itself) to vary its consumption of electrical energy in a given time period. The variation in the consumption of the motor of the vehicle 117 is driven by demands placed on the vehicle for movement (and may therefore be dependent on factors such as location, road conditions, traffic conditions and/or driving style).

[0085] An electrical energy output of the hydrogen fuel cell 113 is electrically connected to the busbar 105 via a boost converter 183. An electrical energy input of the motor of the vehicle 117 is electrically connected to the busbar 105 via a power inverter 185. Finally, an electrical energy connection of the battery 107 is connected to the busbar 105. In use direct current flows through the busbar 105.

[0086] An energy storing system monitoring device (in this case a battery current transducer 187) is provided, which detects the current flow from the battery 107. A load current transducer 189 is provided which detects the current flow in the electrical connection between the busbar 105 and the power inverter 185. A voltage transducer 191 is provided which detects the voltage in the electrical connection between the fuel cell 113 and the boost converter 183.

[0087] Referring to FIG. 7, the controller 123 has a processor 131, a memory 133, a battery current input 135, a load current input 193, a demand modeller input 139, a fuel cell control output 143 and a switch control output 195. The memory 133 is in communication with the processor 131 and stores firmware, software and data for operating the controller 123. The battery current input 135 is arranged to receive data signals from the battery current transducer 187 indicative of the power output of the battery 107 (in this case the current passing from/to the battery 107) through the battery current transducer 187. The demand modeller input 139 is arranged to receive data signals from an energy demand modeller (not shown) indicative of predicted energy demand over the given period by the motor of the vehicle 117. The demand modeller applies the concept of load following prediction. The fuel cell control output 143 is connected to a data input of a fuel cell control module 151 and is arranged to send control signals to vary the control of the fuel cell 113. The processor 131 is arranged to perform processing operations in accordance with programming.

[0088] In use, the energy system 100 generates and supplies electrical energy to the motor of the vehicle 117. Electrical energy to supply the motor of the vehicle 117 is principally generated by the fuel cell 113, which supplies power to the busbar 105 via its electrical energy output and the boost converter 183. Electrical energy is delivered from the busbar 5 to the motor of the vehicle 117 via the power inverter 185 and the electrical energy input of motor of the vehicle 117.

[0089] Nonetheless, it may be that at a particular time the electrical energy required/requested by the motor of the vehicle 117 exceeds the electrical energy deliverable by the fuel cell 113 (e.g. because fuel for the fuel cell is depleted or there is a high demand for electrical energy by the motor of the vehicle 117). Additionally and/or alternatively, it may increase the efficiency of the vehicle under at least some operating conditions to supply at least part of the load requirement of the motor of the vehicle 117 from charge stored in the battery 107. In either circumstance, the battery 107 may meet at least part of the load requirement of the motor of the vehicle 117 at a given time. The battery 107 itself may be charged via the busbar 105 at different times where under particular driving operation the motor acts as a brake and/or where the fuel cell generates a surplus of electrical energy by comparison with the demand of the motor of the vehicle 117. Additionally, in this embodiment, the battery is chargeable via a mains connection (e.g. a plug-in connection when the vehicle is not in use). This need not be the case in other embodiments however.

[0090] As will be appreciated, in response to a change in the rate of electrical energy demand from the motor of the vehicle 117, it will not be possible to adjust the operation of the fuel cell 113 instantaneously to compensate. The battery 107 therefore also behaves as a buffer, supplying/absorbing electrical energy to maintain the potential on the busbar 105 while any adjustments to the fuel cell 113 operation are made. The battery 107 also serves as a sensor, its power consumption, positive or negative, indicating the magnitude of the deficit/surplus, and therefore informing the adjustment required to the fuel cell to compensate (to the extent that it is not desired that the battery 107 should continue to compensate over a longer period).

[0091] The controller 123 controls operation of the energy system 100 as follows. Via its demand modeller input 139, the controller 123 receives updates indicating predicted energy demand in accordance with a load following concept over the given time period of the motor of the vehicle 117 from the energy demand modeller. The energy demand modeller itself receives data signals (i.e. signals from the load current transducer 189) from the motor of the vehicle 117 providing data relevant to present energy demand measurement. The energy demand modeller uses the received data and applies the load following concept to predict energy demand for the motor of the vehicle 117 over the given time period.

[0092] Based on predicted (measured in effect) energy demand for the motor of the vehicle 117, the processor 131 of the controller 123 calculates a baseline for control of the fuel cell 113 over the given time period such that if the predictions were correct, the energy system 100 would remain substantially stable in that the demands of the motor of the vehicle 117 are met and that the battery 107 charge is used in accordance with predetermined rules. An example of such a rule might be that the fuel cell 113 is controlled at any given time in such a manner as to promote battery 107 charge use to contribute to the demand of the motor of the vehicle 117 in proportion to the remaining charge of the battery 107. By way of alternative example, the object of the control could be to maintain the battery charge at a consistent charge level (e.g. approximately 50%) whilst providing/absorbing any electrical energy differential between that generated by the fuel cell 113 and the motor of the vehicle 117, to the extent that the battery 107 has capacity so to do. In the present case however, the object of the control is to split power delivered for a given journey between the fuel cell 113 and the battery 107 in accordance with a power split model. The power split is calculated by the controller 123 based on satellite navigation data including traffic updates. The share of the power delivered by the fuel cell 113 and that delivered by the battery 107 is adjusted using the real time power output of the battery 107.

[0093] In real-time throughout the given time period, the controller 123 adjusts the baseline for control of the fuel cell 113 in accordance with the real time power output of the battery 107 as calculated by the processor 131 in accordance with the received data signals from the battery current transducer 187. It is noted that using the load current from the load current transducer and the supply voltage from voltage transducer 191 would be insufficient to regulate and maintain the share of power supplied by each of the fuel cell 113 and battery 107, because the system controls only the fuel cell power which is subject to efficiency losses at the boost converter 183. Further these losses are nonlinear at lower power regions of the boost converter 183 operation. Thus the present system controls the battery 107 contribution by controlling the fuel cell 113 contribution based on the real time power output of the battery 107.

[0094] Because the power output of the battery 107 indicates the moment by moment discrepancy between generated and demanded energy for the energy system 100, it can be used to make adjustments to control of the energy generated by the fuel cell 113 to bring the contribution of the battery 107 (in terms of provision or absorption of energy) to a desired level. The processor controls the fuel cell 113 accordingly, sending control signals via the fuel cell control output 143. These control signals are received by the fuel cell control module 151, which uses them in combination with data signals it receives from the voltage transducer 191 (indicating the voltage in the electrical connection between the fuel cell 113 and the boost converter 183), to control the boost converter 183. This adjusts the electrical energy provided to the busbar 105 by the fuel cell 113.

[0095] Where the controller 123 determines that there should be no contribution from the fuel cell whatsoever, the controller 123 actuates a switch 197, to break the circuit between the fuel cell 113 and the busbar 105, by sending a signal via its switch control output 195. As will be appreciated, the circuit can again be completed as appropriate. Alternatively, zero contribution from the fuel cell can be achieved by requesting zero power output from the fuel cell control module 151 without using the switch 197 to break the circuit between the fuel cell 113 and the busbar 105.

[0096] As will be appreciated, the baseline for control of the fuel cell 113 may be updated, particularly as new data becomes available. It may be for instance that the baseline is updated continuously e.g. so that it always extends for the pre-determined time period into the future from the current time.

[0097] In the present embodiment, it is desired to gradually deplete the charge level on the battery 107 because it is anticipated that the battery 107 will be periodically re-charged via connection to a charging station. Therefore, the controller 123 controls the fuel cell 113 accordingly, rapidly adjusting its operation to return the battery 107 to a state where there modest discharging is occurring. That is, in this case, the controller 123 operates the fuel cell 113 so that discharge from the battery 107 is maintained at/returned to an energy storing system discharging set point value which is at a predefined non-zero value even where the fuel cell 113 is capable of supplying sufficient electrical energy to match the demand of the motor of the vehicle 117.

[0098] It will be appreciated that embodiments of the present invention can be realised in the form of hardware, software or a combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs that, when executed, implement embodiments of the present invention. Accordingly, embodiments provide a program comprising code for implementing a system or method as claimed in any preceding claim and a machine readable storage storing such a program. Still further, embodiments of the present invention may be conveyed electronically via any medium such as a communication signal carried over a wired or wireless connection and embodiments suitably encompass the same.

[0099] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[0100] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0101] The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.