GB2527806A

GB2527806A - A generator set and control system

Info

Publication number: GB2527806A
Application number: GB1411846.7A
Authority: GB
Inventors: David Hardwick; Jonathan Garnham
Original assignee: JC Bamford Excavators Ltd
Current assignee: JC Bamford Excavators Ltd
Priority date: 2014-07-02
Filing date: 2014-07-02
Publication date: 2016-01-06
Also published as: GB201411846D0

Abstract

A generator set such as a mobile genset 10 having a battery pack 32 for the storage of electrical energy; a first outlet 48 for electrical energy; a second outlet 50 for electrical energy to be supplied from the battery pack; an electrical generator 16 configured to selectively supply electrical energy to the battery pack and to the first outlet; a prime mover such as diesel engine 15 arranged to drive the electrical generator; and a control system 52. The control system is configured to signal operation of the prime mover to seek to maintain state of charge of the battery pack within a desired range, but to provide at least some of the electrical energy supply to the first outlet in response to a demand from a load connected to the first outlet.

Description

Intellectual Property Office Application No. GB1411846.7 RTTVI Date:24 December 20t4 The following terms are registered trade marks and should be read as such wherever they occur in this document:

DIES ELM AX

VICTRON

QUATTRO

U?vlT S Intellectual Property Office is an operating name of the Patent Office www.ipo.govuk A generator set and control system

FIELD OF THE INVENTION

[01] The present invention relates to a generator set and a control system configured to control the operation of a generator set. The present invention further relates to a method of operating a generator set.

BACKGROUND OF THE INVENTION

[02] Mobile generator sets, often refened to as "gensets", typically include a diesel engine arranged to drive an alternator or other form of generator in order to convert the mechanical output from the diesel engine into electrical energy. Such devices are typically used in locations where mains electricity is unavailable ("off-grid" locations), or as a back-up to mains electricity where supplies are unreliable.

Examples of such locations include construction sites, mines, oil and gas installations, open air cultural and sporting events, temporary camps and the like, [03] The generator sets may vary in electrical power output from approx. 5kVA up to around I000kVA, but continue to be portable, e.g. by providing wheels so as to be towable or lifting points for pallet forks or chains.

[04] Different sites have different demands for electricity. Some may have a relatively constant demand throughout a day and/or from day-to-day, whereas other sites may have demands that are variable, Further certain sites may have noise or emissions rules that preclude the use of diesel generators at certain times of day.

[05] Whereas a known diesel powered generator set may operate efficiently if the power demand is constant and its power output is well matched thereto, in other usage scenarios the present applicants have recognised that efficiency may be less than optimal, resulting in excess usage of thel and more frequent maintenance requirements.

[06] It is known to provide a diesel powered generator set in combination with a battery pack, in which the battery pack is periodically charged by the generator set, and in which devices draw their electrical power from the battery pack. This enables the diesel engine to be turned off for certain periods of time, and only mn when the battery pack requires "topping up". However, the present applicant has recognised that this approach continues to have limitations in terms of its ability to power electrical equipment that has a high power demand, but which may only be used intermittently, in conjunction with other electrical equipment that has a lower demand over a longer period of time.

[07] The present invention seeks to overcome or at least mitigate the problems of the

prior art.

SUMMARY OF THE INVENTION

[08] A first aspect of the invention provides a generator set comprising a battery pack for the storage of electrical energy; a first outlet for electrical energy; a second ouliet for electrical energy to be supplied with electrical energy from the battery pack; an electrical generator configured to selectively supply e'ectrical energy to the battery pack and to the first outlet; a prime mover arranged to drive the electrical generator; and a control system; wherein the control system is configured to signal operation of the prime mover to seek to maintain state of charge of the battery pack within a desired range, but to provide at least some of the electrical energy supply to the first outlet in response to a demand from a device attached to the first outlet.

[09] Providing a generator set with a battery pack and maintaining its state of charge within a desired range is advantageous as it enables the prime mover to run intermittently when there is a relatively low demand for power to periodically "top-up" the charge. In turn this may reduce fuel consumption, emissions, and the need to service the prime mover. Maintaining the battery charge within a desired range provides a buffer of reserve power in the battery pack, should there be problems with the operation of the prime mover, and may extend the overall service life of the battery pack. Further this approach ensures that the prime mover is sufficiently loaded when running to avoid problems with engine coking (if the prime mover is an IC engine) and ensure it is operational at an efficient part of its power band. Providing a control system to provide energy to an outlet in response to a demand nevertheless ensures that if there is a power demand that cannot be met by the battery pack, power can be diverted from the battery charging to meet the demand.

[10] In one embodiment, the maximum power output from the prime mover and generator are at least 1.2 times greater than the maximum power at which the battery pack may be recharged, preferably 1.5 times greater, even more preferably 2 times greater.

[11] This arrangement is advantageous as the generator provides more power than can be utilised by the battery pack, ensuring that in typical operation, the generator is able to provide power to the first outlet whilst charging the battery pack.

[12] A second aspect of the present invention provides a generator set comprising a battery pack for the storage of electrical energy; a first outlet for electrical energy; a second outlet for electrical energy to be supplied with electrical energy from the battery paclç an electrical generator configured to selectively supply electrical energy to the battery pack md to the first outlet; and a prime mover arranged to drive the electrical generator; wherein the power output of the prime mover and generator is at least 1.2 times greater than the power at which the battery pack may be charged.

[13] Optional features of the first and second aspects of the present invention are as follows: [14] In one embodiment, the generator is configured to provide all electrical energy being generated to the first outlet if a predetermined criterion is met. Preferably, the predetermined criterion is a predetermined load on the generator.

[15] This arrangement is advantageous as it prevents charging the battery pack in response to a high power demand on the first outlet to ensure that the high power demand can be met.

[16] In one embodiment, the desired range has a lower charge limit greater than 0%.

[17] This arrangement prevents the battery packs from completely emptying which is advantageous as it may extend the service life of the battery pack which results in lower maintenance costs.

[18] In one embodiment, the desired range has an upper limit less than 100%.

[19] This arrangement is advantageous as it increases the overall efficiency of the generator set as when a battery charge has reached a predetermined level, for example 80% for lead acid batteries, it becomes much less efficient to continue charging the battery pack.

[20] In one embodiment, the generator set comprises a mode of operation wherein a load demand sensed on the first outlet causes the prime mover to operate.

[21] This arrangement is advantageous as it allows the generator to start running in response to a demand on the first outlet, rather than running all the time. As such, this increases the overall efficiency of the generator set.

[22] In one embodiment, the generator set comprises a mode of operation where an energy demand up to a predetermined level on the second outlet is provided from the battery pack and above the predetermined level of the demand is supplied at least in part by the generator via the battery pack.

[23] This arrangement is advantageous as it allows for lower amounts of power to be supplied from the battery packs without the requirement of the engine running, but enables higher demands from the second outlet to be met from the generator, thus increasing the overall efficiency of the generator set, whilst avoiding the need to provide a larger battery pack.

[24] Preferably the demand is supplied entirely by the generator.

[25] This arrangement is advantageous as it allows for a high supply of power to the second outlet directly from the engine thus preventing the battery packs from depleting below a predetermined level which extends the service life of the battery pack, or being exhausted.

[26] In one embodiment, the generator set comprises a mode of operation configured such that when the load stops on the first outlet and the battery pack is within a desired range and demand on the second outlet is below a predetermined threshold, the generator is caused to stop.

[27] This mode ensures that the prime mover does not run unnecessarily, saving fuel.

[28] In one embodiment, the generator set comprises a charger to convert AC electricity from the generator to DC electricity for charging the battery pack.

[29] In one embodiment, the generator is a three phase generator and the generator set comprises a charger for each phase thereof [30] This is advantageous as a three phase power system is more economical that a single phase system for distributing power, [3]] In one embodiment, the generator set comprises an inverter to convert the DC electricity from the battery pack to AC electricity for supply to the second outlet.

Preferably, one charger and the inverter are provided as a single unit.

[32] In one embodiment, the first outlet is a three phase outlet.

[33] In one embodiment, the second outlet is a single phase outlet.

[34] In one embodiment, the generator is alternator.

[35] In one embodiment, the prime mover is an internal combustion engine.

[36] In one embodiment, the battery pack and the prime mover are housed in a single unit, [37] In one embodiment, a portion of the unit housing the battery pack is separable from a portion housing the prime mover, [38] This allows for the easy removal and possible exchange or maintenance of the battery pack from the main unit, [39] In one embodiment, the battery pack is housed in a separate unit from the prime mover.

[40] This allows for the easy removal and possible exchange or maintenance of the battery pack from the main unit.

[4]] In one embodiment, the unit housing the battery pack further houses a charger and an inverter.

[42] This arrangement is advantageous as the generator provides more power than can be utilised by the battery pack, ensuring that the generator is able to provide power to the first outlet for high power demand devices, whilst normally being able to charge the battery pack, to provide a separate supply of power to lower demand devices.

[43] A third aspect of the present invention provides a control system configured to control a generator set of a type having a battery pack for the storage of electrical energy; a first outlet for electrical energy; a second outlet for electrical energy to be supplied with electrical energy from the battery pack; an electrical generator configured to selectively supply electrical energy to the battery pack and to the first outlet; and a prime mover arranged to drive the electrical generator; wherein the control system is configured to signal operation of the prime mover to seek to maintain a state of charge of the battery pack within a desired range, but to further control the charging of the battery pack so as to provide at least some of the electrical energy supply to the first outlet in response to a demand from a device attached to the first outlet.

[44] Providing a control system control a generator set with a battery pack and maintaining its state of charge within a desired range is advantageous as it enables the prime mover to run intermittenfly when there is a relatively low demand for power to periodically "top-up" the charge. In turn this may reduce fuel consumption, emissions, and the need to service the prime mover. Maintaining the battery charge within a desired range provides a buffer of reserve power in the battery pack, should there be problems with the operation of the prime mover, and may extend the overall service life of the battery pack, Further this approach ensures that the prime mover is sufficiently loaded when mnning to avoid problems with engine coking (if the prime mover is an IC engine) and ensure it is operation at an efficient part of its power band.

Providing a control system to provide energy to an outlet in response to a demand nevertheless ensures that if there is a power demand that cannot be met by the batten', power can be diverted from the battery charging to meet the demand.

[45] In one embodiment, the control system is configured to signal the provision of all electrical energy being generated to the first outlet if a predetermined criterion is met.

[46] In one embodiment, the predetermined criterion is a predetermined load on the generator.

[47] This arrangement is advantageous as it prevents charging the battery pack in response to a high power demand on the first outlet to ensure that the high power demand can be met.

[48] In one embodiment, the desired range has a lower charge limit greater than 0%.

[49] This arrangement prevents the battery packs from completely emptying which is advantageous as may extend the service life of the battery pack which results in lower maintenance costs.

[50] In one embodiment, the desired range has an upper limit less than 100%.

[51] This arrangement is advantageous as it increases the overall efficiency of the generator set as when a battery charge has reached a predetermined level, for example 80% for lead acid batteries, it becomes much less efficient to continue charging the battery pack.

[52] In one embodiment, the control system comprises a mode of operation wherein a load demand sensed on the first outlet causes the prime mover to operate.

[53] This arrangement is advantageous as it allows the generator to start running in response to a demand on the first outlet, rather than running all the time, As such, this increases the overall efficiency of the generator set.

[54] In one embodiment, the control system comprises a mode of operation where an energy demand up to a predetermined level on the second outlet is provided from the battery pack and above the predetermined level of the demand is supplied at least in part by the generator via the battery pack.

[55] This arrangement is advantageous as it allows for lower amounts of power to be supplied from the battery packs without the requirement of the engine running, but enables higher demands from the second outlet to be met from the generator, thus increasing the overall efficiency of the generator set, whilst avoiding the need to provide a larger battery pack.

[56] In one embodiment, the demand is supplied entirely by the generator.

[57] This arrangement is advantageous as it allows for a high supply of power to the second outlet directly from the engine and thns preventing the battery packs from depleting below a predetermined level which extends the service life of the battery pack, or being exhausted.

[58] In one embodiment, the control system comprises a mode of operation configured such that when the load stops on the first outlet and the battery pack is within a desired range and demand on the second outlet is below a predetermined threshold, the generator is caused to stop.

[59] This mode ensures that the prime mover does not mn unnecessarily, saving fuel.

[60] In one embodiment, the control functions are distributed between at least a main control module and a charger inverter, [6]] Advantageously, this enables the additional functionality of the present invention to be provided by with the minimum amount of customisation.

[62] A fourth aspect of the present invention provides a method of operating a mobile generator set according to any preceding claim, the method comprising the steps of operating the generator set to maintain a state of charge of the battery pack within a desired range by selectively running the prime mover to charge the battery pack if it becomes depleted; ceasing or reducing charging of the battery pack in the event that a demand from a device attached to the first outlet exceeds a predetermined threshold.

[63] BRIEF DESCRIPTION OF THE DRAWINGS

[64] Embodiments of the invention will now be described with reference to the accompanying drawings, in which: [65] Figures 1 and 2 are isometric and side views of a generator set according to an embodiment of the present invention; [66] Figure 2A is a cutaway side view schematically illustrating the location of components within the generator set; [67] Figures 3 and 4 are isometric and side views of a lower portion on the generator set of Figures 1 and 2 [68] Figure 5 is a schematic diagram of the maj or components of the generator set of Figures 1 and 2; [69] Figure 6 is a flowchart illustrating operation of the generator set of Figures t and 2; and [70] Figure 7 is a schematic diagram of a generator set according to a different embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENT(S)

Physical layout [71] With reference to the Figures the generator set 10 (hereinafter "genset") comprises a canopy U having a largely conventional upper portion 14 including a prime mover (a diesel internal combustion engine 15 in this embodiment) mounted fore-aft and having an output drive coupled to a generator in the form of a three phase alternator 16. The upper portion further includes a fuel tank 18, a cooling system comprising a fan 19 driven by the engine, and at the bottom of thereof, a bund 28 is provided so as to capture any fluid leaks.

[72] The upper portion also includes part of a control system 20, including a control panel with control inputs 22 and a display 24. Additionally, in this embodiment, the upper portion 14 includes an AC/DC converter in the form of three chargers 26a, 26b, 26c. The bund 28 has a passage through it with a liquid impervious side wall around it to route cables (not shown) down to a lower portion 30 beneath the bund, but without compromising its capacity to capture fluid.

[73] The canopy further comprises the lower portion 30 shown in more detail in Figures 3 and 4. The lower portion 30 has substantially the same footprint as the upper section 14 and principally houses a battery pack 32. In this embodiment the battery pack comprises 24 2V lead acid batteries 34 (12 visible in Figure 4) with a gel electrolyte to prevent leakage, and arranged on racks 36 in two layers. Individual batteries 34 may be slid from the rack for inspection or replacement. In other embodiments different battery types may be used, such as Nickel Cadmium or Lithium Ion and the capacity and number may be adjusted as required.

[74] Considering the upper portion 14 in more detail in relation to Figures 1 and 2 it can be seen that the canopy is formed from sheet metal in a conventional manner, with various access doors provided therein in order to access the control inputs 22 and display 24, and for maintenance purposes. In addition, grilles and louvres are provided to allow air to flow through the canopy.

[75] In this embodiment, louvres 38 are provided in a lower portion of side walls of the canopy 12 at the right hand side as viewed in Figures 2 and 2A for air to be drawn in. A baffle (not visible) directs the intake air upwards past the chargers 26a, 26b, 26c so as to cool them. The air is the drawn from right to left past the generator 16 and engine 15 through the fan 19 and a heat exchanger 40 for the engine, before being exhausted through a grille 42 seen most clearly in Figure 1 Dotted arrow A illustrates this air flow path. This arrangement advantageously enables the chargers 26a, 26b, 26c to be cooled by the incoming air before it becomes significantly heated by the engine 15 downstream, The equivalent space occupied by the chargers 26a-26c has hitherto been vacant in known gensets.

[76] The lower portion 30 is also fabricated from sheet metal, with the internal racks 36 also being sheet metal. In this embodiment the end walls comprise louvres 38 and further louvres 38 are provided on each of the side walls. At each end, between the racks 36 and the end walls, four electric fans 44 are provided to draw air in and through the end louvres and out through the side wall louvres. As can be seen in Figure 3, vertical sections of the racks 36 are perforated to assist in the circulation of air. This arrangement provides for good airflow (illustrated by arrows B) to cool the batteries 34 without this being affected by heat generated in the upper portion 14. The use of multiple fans 44 allows for redundancy in case of a fan failure.

[77] As can be seen in Figure 3, an opening 46 is provided in the top of the lower portion 30 for cabling from the battery pack 32 to pass through and into the upper portion 14.

[78] The lower portion 30 further includes through apertures 45 such that the genset tO may be lifted using pallet forks. Panels 47 on the side walls are removable (e.g. by removing screws) to access the batteries 34 for inspection and maintenance.

[79] In this embodiment, the upper and lower portions 14, 30 are provided as separate self-contained sections, attachable using releasable fasteners such as bolts, The upper and lower portions 14, 30 are secured together via a perforated connecting plate 62, which is secured proximate the bottom corners of the side faces of the upper and lower portions. The upper and lower portions 14, 30 include angled perforated mounting plates 64, 66 which protrude from the side faces of the upper and lower portions at an angle of around 20 degrees to the vertical. The connecting plate 62 is secured to the mounting plate 64 of the lower portion 30 via bolts 68 secured through the perforations, resulting in the connecting plate 62 extending over the top edge of the lower portion 30, [80] Upon lowering of the upper portion 14 onto the lower portion 30, as in during assembly of the portions, the angled mounting plates 66 assists in aligning the upper portion with the lower portion as the bolts are tightened, thus allowing for an easier assembly, [81] This enables the lower portion 30 to be exchanged, for example to swap a frilly charged battery pack 32 for a discharged pack, or to switch a genset 10 between having a battery storage option and no battery storage.

[82] In other embodiments, the upper and lower portions 14, 30 may be formed as a single, non-separable unit, In these embodiments, the battery pack may nevertheless be removed as a whole or via two or more subassemblies/supports to ease the exchange thereof In further embodiments, the genset may be provided with wheels and a tow bar so as to be transported as a trailer.

Functional layout [83] With reference to Figure 5 the functional layout of the genset 10 is illustrated in more detail. In this Figure, solid lines indicate a power supply connection, dotted lines a signal line, and dot-dash lines a Controller Area Network (CAN) bus connection.

[84] In this embodiment, the prime mover is a four cylinder Dieselmax diesel internal combustion engine 15 manufactured by the present applicant, with a power output of 50kW (to provide 6OkVA of power). However similar engines may be rated to output 100kW (to provide approx. 120kVA of power). This is mechanically coupled to a three phase generator, suitable for providing three phase electrical power to industrial plant equipment via four three phase outlet sockets/terminals, [85] In addition, the alternator 16 is connected to the three chargers 26a, 26b, 26c.

Each charger is configured to convert one phase of AC into DC to charge the battery pack 32, when required. This arrangement ensures the battery pack may be charged at the maximum rate possible, when required.

[86] In this embodiment, the battery pack 32 is capable of being charged at a rate of 25kW (i.e. approx. half the output of the engine 15) and at this charging rate it will take approximately two and a half hours to reach an 80% battery charge. Above an 80% battery charge, it becomes less efficient to charge the battery pack, such that above this battery level it would not be as efficient to run the engine simply for the purpose of charging the batteries.

[87] Further, the battery pack 32 has a total storage capacity of 4OkWh. However to maintain lead acid batteries of this type in good condition for a long service life, it is preferred to avoid the battery pack dropping below a 50% charge, although this parameter differs for different battery types.

[88] The maximum output power for a continuous load of the battery pack 32 is 10k VA, although a peak output of 2OkVA is possible for 5 seconds. Thus, it will be appreciated that the power output for the batten' pack 32 is significantly lower (approx, 1/6th) the power output of the engine 15 and alternator 16.

[89] In this embodiment, one of the chargers 26c is a combination inverter/charger.

Thus, charger 26c is able to convert the DC power from the battery to single phase AC to be supplied to a further outlet socket 50, hereinafter referred to as a hybrid socket.

[90] In this embodiment the two chargers 26a and 26b are Skylla model chargers from Victron Energy of Almere Haven, The Netherlands. The inverter charger is a Victron Quattro model. In addition, the three chargers comprise an inbuilt control capability which works in conjunction with a main control module 52 to ensure the genset runs as intended. Specifically, the chargers 26a to 26c operate in conjunction with a battery monitor 54 to be aware of various battery parameters including percentage charge and battery temperature. In addition, the chargers may be set such that when the three phase outlet 48 is consuming a maximum amount of the power generated by the alternator 16, no power is taken and converted to DC for the charging of the battery pack. Further, the inverter charger 26c is capable of signalling that the engine 15 needs to be started to supply this demand.

[91] The main control module 52 is in this embodiment, a microprocessor controller of a type known for use in the control of prior art generators, but with additional functionality added thereto, In this embodiment the control module is a DSE74IO model manufactured by Deep Sea Electronics plc of Filey, North Yorkshire, UK.

[92] The main control module 52 is capable of communicating with the engine 15, alternator 16 and chargers 26a to 26c via a CAN bus, alternatively this communication may be via direct analogue connectors. As such, it is capable of receiving operating parameters of the aforesaid components, such as engine speed, engine load, loading on each phase, battery data and the! level, and is also capable of signalling engine start and controlling the fuel supply to the engine IS. In addition, the control module 52 is further capable of sensing a load applied to the three phase outlets and on receipt of this signal, instrncts engine start.

[93] In addition, in this embodiment, the genset 10 comprises a telemetry module 56, The telemetry module 56 comprises a transmitter capable of communicating via a cellular radio network using a suitable protocol, such as GPRS, UMTS or LIE, and the internet 58 with a central server 60 at a remote location, such that operating parameters of the machine may be presented to authorised users and, for example, reports generated of machine usage, machine location etc. To enable this, the telemetry module 56 is capable of collecting data from the engine 15, alternator 16, control module 52 and the chargers 26a to 26c.

Genset operation [94] With reference in particular to Figures 5 and 6, operation of the genset 10 is as follows: [95] Upon delivery to a particular operating site, for example a construction site, an operator initially determines which electrical devices are to be attached to which outlet sockets. For example, site office devices would typically be connected to the hybrid outlet socket 50 since heating, cooling, security cameras, computers and lighting are usually relatively low demand devices which are on for extended periods of time. In addition, certain of these functions, such as security cameras and computers require a supply that is instantly available and not interruptible.

[96] Other devices on a site, such as cranes, concrete mixers and large power tools would typically be used intermittently but require a significantly larger supply of power. Accordingly, such devices are plugged into the three phase outlet sockets 48.

[97] Thus, staffing the process at step 5100, assuming the genset 10 is fuelled with diesel, has some battery charge and is turned on, the user can select various operating modes using inputs 22.

[98] If at step S102 a switch to select whether power from the hybrid socket is available is turned to off, then no power is supplied to the hybrid outlet at step 5103 and only power may be provided via the three phase outlets 48.

[99] Then if at step 5104 the user selects the manual mnning mode by selecting a manual switch to on, the engine 15 starts and runs permanently at step Si 06. If the manual switch is not on, the operator may instead have selected a timer mode at step 5108 to, for example, run the engine for the working hours of a construction site in order to provide penuanent three phase power to the outlets 48. If the timer is operational and set to on, then the engine is set to run at step 106.

[100] If at step SI 10 the timer is not on, but the charge on the batteiy pack 32 is detected by the battery monitor 54 as being less than a predetermined desirable value (in this embodiment less than 50%) then the control module 52 signals the engine to run at step 106.

[101] If at step SI 12 the battery charge is at greater than 50%, but the inverter charger 26c determines that the load on the hybrid socket 50 is greater than a predetermined threshold, in this embodiment, greater than 7kW then the inverter charger 26c signals the control module 52 accordingly and the control module signals the engine to run at step S 106.

[102] An operator may also select whether the "start on demand" function is available, and at step S114 the control system confirms if this is enabled. If start on demand is on and the control module 52 determines there is a load on the three phase outlet 48, at step S116 the control module 52 in turn signals the running of the engine at step S 106, [103] At step S118, once the engine is running, power becomes available at the three phase outlets 48. Typically the time from detecting a demand to being able to supply power to meet that demand is five seconds or less.

[104] At step S120 the control module 52 determines if the load on the alternator 16 is greater than a predetermined threshold. In certain embodiments, this may cause charging to cease. However, in preferred embodiments, this may cause charging to reduce in stages. Thus, once an average load of 80% of maximum is reached, for example, the phase with the highest load ceases to charge. Then, if the average load reaches 85% another charger ceases to charge, and finally if the average load reaches 90%, the final, most heavily loaded charger ceases to charge. As well as ensuring that the alternator 16 and engine 15 are not too heavily loaded, this approach assists in balancing the phases. It will also be appreciated that due to hysteresis, transient spikes in load on a phase may not cause charging to cease on that phase.

[105] Nevertheless, if the upper limit is reached, then at step S122 the control module 52 signals the chargers 26a to 26c to stop charging the battery pack in order to provide available capacity to the three phase outlets 48.

[106] If however, capacity is available, at step 5124 the control module 52 signals the chargers to charge the batteries, If, at step S126, the battery charge is above a predetermined value the control module 52 signals the chargers to stop charging the batteries. If the engine is mnning, at step S 0 due to the battery charge being less than 50% then the predetermined value is 80%. If however, the engine is running at steps Sf12 or Si 16 due to a load on the genset then the predetermined value is 100%.

This is because, despite charging being less efficient above 80%, if spare power is available it is sensible for it nevertheless to be used for charging.

[107] In this embodiment this approach is preferred because lead acid batteries become less efficient to charge when above 80% battery charge. As such, this approach is used to increase the overall efficiency of the genset.

[108] Whilst the flow chart of Figure 6 shows a single cycle of operation, it will be appreciated that the steps may operate as a continuous loop. By way of example, after a delay of; for example, one minute step SI 16 is repeated and if no load, is detected, then the control module 52 signal the engine to stop. It will further be appreciated that the predetermined parameters may be overridden automatically, or by operator override in some circumstances. For example, if the engine is unable to run due to lack of fuel or malfunction, the control module may be programmed to continue the supply of power to the hybrid outlet until the battery is exhausted or a lower absolute minimum charge level is reached. In this instance, the control module 52 emits an alarm on the machine or remotely via the telemetry module 56 which sends an alert to a remote operator via the internet 58 and server 60.

Two part generator set [109] Figure 7 illustrates a genset according to a second embodiment of the present invention in which like parts are labelled by like numerals as the first embodiment, but with the addition of the prefix "2". Only differences with the first embodiment are discussed in more detail.

[110] The second embodiment of Figure 7 differs principally in that the genset 210 comprises two separate parts; a main part 210a housing the engine 215, alternator 216, control module 252 and outlets 248 and a separate "battery box" 21Gb which houses the battery pack 232 and a charger/inverter 226c, as well as a cooling mechanism (fans not shown).

[11] This arrangement permits an existing conventional generator (either from the present applicant or a third party) to be converted into a hybrid generator that may share many of the advantages of the first embodiment quickly and at reasonable expense. In this embodiment the battery box 210b has a plug to plug into an outlet socket 248 of the main part 210a and draw power therefrom.

[112] The AC power is fed into a single phase charger/inverter 226, which in this embodiment is a Victron Quattro similar to the first embodiment, to convert AC to DC to charge the batteries, and in reverse to supply power to the hybrid ontlet with single phase AC when required. The use of single phase power for charging slows the process somewhat, but enables the battery box 21Db to be compatible with a broad range of generators. In other embodiments a three phase arrangement similar to the first embodiment may be used.

[113] The charger/inverter 226 is connected to a battery monitor 254 so to have data on battery condition. In this embodiment, the only signal line between battery box is a two-wire remote start connection, again so as to maintain broad compatibility with a range of generators, some of which may not have a CAN bus (although a CAN connection could be provided in other embodiments).

[114] Nevertheless, this arrangement permits the charger/inverter 226 to signal to the control module 252 to start the engine in order to maintain a desired battery charge level, Further, assuming the engine 215 and generator 216 have a greater output capacity than the battery pack 232, the generator is still capable of supplying power to the remaining three phase outlets which also charging the battery.

Variants [115] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims, [116] For example the genset may use capacitors or other means of energy storage rather than batteries. The size of engine and battery pack may be scaled up or down as required. A genset of the first embodiment may be used in conjunction with a battery box of the second embodiment to add to the amount of energy storage available.

Although desciThed in relation to mobile gensets, the present invention may also be applicable to permanent/static gensets, Other types of prime movers may be utilised such as gas turbines, Additionally the genset may have inputs such that the battery can also be charged from renewable sources such as solar cells and wind turbines, Other suitable arrangements for releasably attaching the upper and lower portions may be used instead of the perforated p'ates and bolts.

Claims

Claims I. A generator set comprising: a. a battery pack for the storage of electrical energy; b. a first outlet for electrical energy; c. a second outlet for electrical energy to be supplied with electrical energy from the battery pack; d, an electrical generator configured to selectively supply electrical energy to the battery pack and to the first outlet; e. a prime mover arranged to drive the electrical generator; and f a control system; wherein the control system is configured to signal operation of the prime mover to seek to maintain state of charge of the battery pack within a desired range, but to provide at least some of the electrical energy supply to the first outlet in response to a demand from a device attached to the first outlet.
2. A generator set according to claim 1 wherein the maximum power output from the prime mover and generator are at least 1.2 times greater than the maximum power at which the battery pack may be recharged, preferably 1.5 times greater, even more preferably 2 times greater.
3. A generator set comprising: a. a battery pack for the storage of electrical energy; b. a first outlet for electrical energy; c. a second outlet for electrical energy to be supplied with electrical energy from the battery pack; d. an electrical generator configured to selectively supply electrical energy to the battery pack and to the first outlet; and e. a prime mover arranged to drive the electrical generator; wherein the power output of the prime mover and generator is at least 2 times greater than the power at which the battery pack may be charged. 2]
4. A generator set according to any preceding claim configured to provide all electrical energy being generated to the first outlet if a predetermined criterion is met.
5. A generator set according to claim 4 wherein the predetermined criterion is a predetermined load on the generator.
6. A generator set according to claim 1 or any preceding claim when dependent on claim 1 wherein the desired range has a lower charge limit greater than O?/b,
7. A generator set according to claim I or any preceding claim when dependent on claim I wherein the desired range has an upper limit less than 100%.
8. A generator set according to any preceding claim comprising a mode of operation wherein a load demand sensed on the first outlet causes the prime mover to operate.
9. A generator set according to any preceding claim comprising a mode of operation where an energy demand up to a predetermined level on the second outlet is provided from the battery pack and above the predetermined level of the demand is supplied at least in part by the generator via the battery pack.
10. A generator set according to claim 9 wherein the demand is supplied entirely by the generator.1. A generator set according to any preceding claim comprising a mode of operation configured such that when the load stops on the first outlet and the battery pack is within a desired range and demand on the second outlet is below a predetermined threshold, the generator is caused to stop.12. A generator set according to any preceding claim further comprising a charger to convert AC electricity from the generator to DC electricity for charging the battery pack.13. A generator set according to claim 12 wherein the generator is a three phase generator and the generator set comprises a charger for each phase thereof 14. A generator set according to any preceding claim further comprising an inverter to convert the DC electricity from the battery pack to AC electricity for supply to the second outlet.15. A generator set according to claim 14 wherein one charger and the inverter are provided as a single unit.16. A generator set according to any preceding claim wherein the first outlet is a three phase outlet.17. A generator set according to any preceding claim wherein the second outlet is a single phase outlet.18. A generator set according to any preceding claim wherein the generator is alternator.19. A generator set according to any preceding claim wherein the prime mover is an internal combustion engine.20. A generator set according to any one of claims 3 to 19 wherein the maximum power output from the prime mover and generator are at least 1.5 times greater than the maximnm power at which the battery pack may be recharged, preferably 2 times greater.21. A generator set according to any preceding claim wherein the battery pack and the prime mover are housed in a single unit.22. A generator set according to claim 21 wherein a portion of the unit housing the battery pack is separable from a portion housing the prime mover.23. A generator set according to any one of claims 1 to 21 wherein the battery pack are housed in a separate unit from the prime mover.24. A generator set according to claim 23 wherein the unit housing the battery pack further houses a charger and an inverter.25. A control system configured to control a generator set of a type having a battery pack for the storage of electrical energy; a first outlet for electrical energy; a second outlet for electrical energy to be supplied with electrical energy from the battery pack; an electrical generator configured to selectively supply electrical energy to the battery pack and to the first outlet; and a prime mover arranged to drive the electrical generator; wherein the control system is configured to signal operation of the prime mover to seek to maintain a state of charge of the battery pack within a desired range, but to further control the charging of the baftery pack so as to provide at least some of the electrical energy supply to the first outlet in response to a demand from a device attached to the first outlet.26. A control system according to claim 25 configured to signal the provision of all electrical energy being generated to the first outlet if a predetermined criterion is met.27. A control system according to claim 26 wherein the predetermined criterion is a predetermined load on the generator.28. A control system according to any of claims 25 to 27 wherein the desired range has a lower charge limit greater than 0%.29. A control system according to any of claims 25 to 28 wherein the desired range has an upper limit less than 100%.30. A control system according to any of claims 25 to 29 comprising a mode of operation wherein a load demand sensed on the first outlet causes the prime mover to operate.31. A control system according to any of claims 25 to 30 comprising a mode of operation where an energy demand up to a predetermined level on the second outlet is provided from the battery pack and above the predetermined level of the demand is supplied at least in part by the generator via the battery pack.32. A control system according to claim 31 wherein the demand is supplied entirely by the generator.33. A control system according to any of claims 25 to 32 comprising a mode of operation configured such that when the load stops on the first ouflet and the battery pack is within a desired range and demand on the second outlet is below a predetermined threshold, the generator is caused to stop.34. A control system according to any of claims 25 to 33 wherein the control functions are distributed between at least a main control module and a charger inverter.35. A method of operating a mobile generator set according to any preceding claim, the method comprising the steps of a. operating the generator set to maintain a state of charge of the battery pack within a desired range by selectively running the prime mover to charge the battery pack if it becomes depleted; b. ceasing or reducing charging of the battery pack in the event that a demand from a device attached to the first outlet exceeds a predetermined thresholdS