BE1031561B1 - METHOD FOR ELECTRICALLY DRIVING A MOBILE COMPRESSOR AND SUCH COMPRESSOR - Google Patents

Abstract

According to an embodiment, an electrically powered mobile compressor (300) is disclosed comprising an electric motor (106) for driving a compressor element (107), comprising an electrical connection (108) for an electricity grid and connected to an electrical distribution device (101) further comprising an on-board charger (103) configured to provide electrical power thereto (101) from the electricity grid (108), a battery management system (104) for supporting a power exchange between the distribution device (101) and an assembly of one or more rechargeable batteries (109, 202), a controller (100) for measuring an electrical consumer current (110) to the electric motor (106), and determining a maximum charging current (112) for the rechargeable batteries (109, 202), the controller (100) further configured to control the on-board charger (103) so that an electrical power (111) is provided from the electricity grid (108) corresponding to the sum of the consumer current (110) and the maximum charging current (112).

Description

METHOD FOR ELECTRICALLY DRIVING A

MOBILE COMPRESSOR AND SUCH COMPRESSOR

Technical Area

[01] The present invention relates to an electrically driven compressor and to a method for controlling such an electrically driven compressor.

State of the art

[02] A compressor is a machine designed to produce compressed gases, such as compressed air. The compressed gas at a certain working pressure is then used in a range of applications, such as driving other machines such as pneumatic drills and drilling machines.

[03] Such drills and drilling machines are usually used at locations where there is no fixed compressed air network, such as a construction site. Typically, a mobile compressor is used at these locations. The term mobile is therefore understood to mean that such a compressor is movable, with or without the aid of means of transport and/or hoisting equipment. In other words, a mobile compressor is a compressor that is not designed to be used stationary at a fixed location.

[04] Mobile compressors can be powered by a diesel engine so that they can operate independently. However, since they emit combustion gases and are noisy, there is a tendency to replace these diesel engines with an electric motor. An electricity network must then be present to power this electric motor.

[05] In BE1024040A1 such an electrically driven mobile compressor is disclosed. In this case, the mobile compressor is equipped with a control unit to limit the maximum electrical current consumption to an adjustable maximum value. This prevents the electricity grid to which the mobile compressor is connected from being overloaded.

[06] As further disclosed in BE1024040A1, the energy supply from the electricity grid can be further supplemented with a set of batteries. When the mobile electrically powered compressor is not active but connected to the electricity grid, the batteries can be charged. When the mobile electrically powered compressor is operational, the electric mobile compressor can draw electrical power from the electricity grid. If the grid were to fail afterwards, work can continue using power that can be drawn from the charged batteries.

[07] A disadvantage of this disclosed electrically powered mobile compressor and the associated method of controlling it is that it cannot be guaranteed that electrical power is available at all times.

[08] It is therefore an object of the present invention to provide a device and method that overcomes one or more of the described disadvantages of prior art solutions. More specifically, it is an object of the present invention to provide a device and method that leads to greater autonomy of an electrically powered mobile compressor.

Summary of the invention

[09] According to the present invention, the above-identified object is achieved by, according to a first aspect of the invention, providing a computer-implemented method according to claim 1 for controlling an electrically powered mobile compressor comprising a compressor element driven by an electric motor for supplying a compressed gas under a predefined pressure, the electric motor connected to an electrical distribution device for supplying an electrical consumer current, the distribution device further comprising: - an on-board charger configured to supply electrical power to the electrical distribution device from an electricity grid; and - a battery management system configured to support a power exchange between the distribution device and an assembly of one or more rechargeable batteries; the method comprising the steps of: - measuring the electrical consumer current to the electric motor when active; and - determining a maximum charging current for the assembly of the one or more rechargeable batteries using the battery management system; whereby the on-board charger is controlled so that an electrical power is supplied from the electricity grid corresponding to the sum of the consumer current and the maximum charging current.

[10] The electrically powered mobile compressor is configured to provide compressed air at a location where there is usually no compressed air network. On the other hand, there is an electricity network available to power the compressor.

For example, this electricity grid is a low-voltage grid at a certain voltage, such as 400V, which is common in Europe, or 480V, which is common in the

United States of America. It should therefore be understood that the value of the voltage to which the mobile compressor can be connected is not restrictive, but can be adapted to the region where the compressor will be used.

[11] The compressor is equipped with an electric motor to drive a compressor element. The compressor element is for example a screw when the compressor is of the screw compressor type. Here too it should be further understood that the type of compressor element is not limiting and that other compressor elements can be used to deliver the compressed gas under a predefined pressure. The value of this pressure is further dependent on the intended applications, and can also be adjustable.

[12] Furthermore, there may be a mechanical coupling between the electric motor and the driven compressor element, such as a gearbox.

In other words, the drive of the compressor element should not be a direct drive by the electric motor, but a mechanical coupling between them can also be provided. This will convert the speed of the electric motor into a speed suitable for the compressor element.

[13] Furthermore, the type of electric motor is also not limiting for the disclosed invention. This can be a three-phase asynchronous electric motor, as well as a three-phase permanent magnet synchronous motor. In these cases, there will be a frequency converter between the electrical distribution system and the motor. This frequency converter, also called frequency controller, inverter, or variable speed drive, VSD, will then convert a direct voltage from the electrical distribution system into an alternating voltage with a specific frequency suitable for the three-phase electric motor. Furthermore, both the frequency and the alternating voltage can change in order to be able to supply a specific torque to the compressor element, and this as a function of the required pressure of the compressed gas.

[14] Alternatively, the electric motor can be of the DC motor type. In this case, the DC motor can be connected directly to the electrical distribution system, but as a rule, there will be a DC/DC converter between the electrical distribution system and the DC motor in order to be able to apply a terminal voltage 5 suitable for this.

[15] In addition, there may also be multiple electric motors present, each of which individually drives a compressor element. In this case, a frequency controller can be provided for each electric motor. Another possible configuration is that a single electric motor drives two or more compressor elements. When referring to a current for the electric motor, this also refers to the total electric current required to drive the one or more motors.

[16] The current that then flows between the electrical distribution system and the electric motor is further referred to as the electrical consumer current, or simply consumer current. Note further that this consumer current is also the current that is required to drive the compressor element and thus provide compressed gas when the compressor is operational.

[17] The electrical distribution system is a voltage rail, also called a busbar, to distribute electricity between the various connected devices. A first device is therefore the electric motor just discussed. The consumer current then runs from the electrical distribution system to the electric motor.

[18] A second device connected to the electrical distribution system is an on-board charger. The on-board charger is configured to convert electrical power from the electricity grid to a suitable value for and make it available to the electrical distribution system. Usually, an alternating current from the electricity grid will be converted to a direct current. Here, an electrical current will flow from the electricity grid through the on-board charger to the electrical distribution system in order to make this electrical power available to the various electrical consumers connected to it.

[19] Another device connected to the electrical distribution system is a battery management system. The battery management system is configured to support a power exchange between the distribution system and an assembly of one or more rechargeable batteries by monitoring the state of charge of this assembly. To support this, the current, voltage and temperature of the one or more batteries are measured and data is exchanged with a controller on the basis of this. The controller then calculates a set point for the on-board charger and sends the result to the on-board charger.

This allows the power exchange to take place in an optimal way. The battery management system will also include a safety function to protect the batteries by not discharging them too deeply. Discharging occurs, for example, when another electrical consumer, such as the electric motor to drive the compressor element, connected to the electrical distribution system, consumes electrical power when there is no electricity grid present, or the electricity grid is insufficient.

[20] In other words, the battery management system is a system as known in the state of the art. It will therefore ensure that the batteries are kept in a safe and reliable condition. This is done, among other things, by monitoring the charge status and ensuring that the batteries are not discharged too deeply, as will be explained further.

[21] The connected set of rechargeable batteries is further characterized by a maximum charging current. This is the maximum value of the current with which the batteries can be charged in a safe and efficient manner. As will be explained further, this value depends on the charge status of the set of batteries. In principle, however, it will be considered a fixed value.

[22] The method further comprises the step of measuring the electrical consumer current discussed above. This measurement is done, for example, on the electric motor, or via a current measurement on the electrical distribution system by means of a shunt or another measuring device suitable for determining the current. Note further that if the electric motor is of the asynchronous three-phase type, this electrical alternating current can also be measured. In this case, a conversion will then take place to a corresponding direct current, taking into account conversion losses of the frequency converter. In other words, it should be understood that a value of a direct current is measured, directly or indirectly, which is characteristic for driving the electric motor which in turn drives the compressor element.

[23] A second step in the method is to determine the maximum charging current of the rechargeable batteries, as explained above. This is determined using the battery management system.

[24] Furthermore, according to a new and innovative concept, the on-board charger will be further controlled so that electrical power is supplied from the electricity grid corresponding to the sum of the consumer current and the maximum charging current.

[25] In other words, not only is the consumer current provided to power the electric motor and thus drive it when an electricity grid is present, but also an additional power to be able to charge the battery set simultaneously with the compressor being operational. In other words, the batteries can be charged simultaneously with keeping the compressor operational.

[26] An on-board charger as known in the state of the art is configured to charge the batteries via the battery management system when other connected consumers, such as an electric motor, are not active. In other words, in the state of the art, one will either drive an electric motor from the set of batteries, or charge the batteries via a connected electricity grid. There is therefore either an electrical power flow from the batteries to the electric motor, or an electrical power flow from the electricity grid to the batteries. A final possibility is that there is a direct power flow from the electricity grid to the electric motor. According to the disclosed invention, one therefore realises a power transfer from the electricity grid to both the electric motor and to the set of one or more rechargeable batteries.

[27] A first advantage of controlling the on-board charger in this way is that the autonomy of the mobile compressor can be increased. By being able to charge the batteries while the compressor is operational, one ensures that they remain in a charged state, or at least can be charged. If the electricity grid were to fail, one can effortlessly switch to the batteries to supply the electric motor with electrical power. One can then try to identify the cause of the failure of the electricity grid, without having to abruptly stop the work that has to be carried out with the mobile compressor.

[28] Another advantage is that when starting work carried out using the compressor, one does not have to choose between starting work immediately on the one hand, and charging the batteries if they are in a discharged or partially discharged state on the other. One can therefore start work immediately, with the on-board charger ensuring that the batteries are charged if necessary.

[29] A third advantage is that the electricity grid can be used optimally in this way when present, because more power can be drawn from the grid than is needed for the operation of the compressor. Again, this allows one to anticipate a possible failure of the electricity grid and to charge the batteries in the meantime.

[30] According to an embodiment, an additional connection may be provided on the electrical distribution system for an electrical consumer other than the electric motor and the battery management system. This connection is, for example, a socket to which an electrical appliance can be connected. The electrical current that this appliance consumes is referred to as the electrical demand current, or simply demand current.

[31] The method will then further include the step of measuring this demand current, whereby the on-board charger is then further controlled so that the electrical power from the electricity grid corresponds to the sum of the consumer current for the electric motor, the charging current for charging the batteries, and the aforementioned demand current for the electrical appliance.

[32] This will again ensure that the batteries can be charged when they are discharged or partially discharged, while the electrical appliance can be supplied with the necessary power.

[33] According to a preferred embodiment, the method further comprises the steps of: - determining the charge state of the composition of the one or more rechargeable batteries using the battery management system; and - adjusting the maximum charging current when the charge state exceeds a predefined value.

[34] In other words, the charge status of the rechargeable batteries will be continuously monitored and the maximum charging current determined on this basis. Adjusting the maximum charging current can then be done in two ways.

[35] When the state of charge exceeds a certain value in an upward direction, for example more than 90% charged, the charging current will be limited so that the batteries are charged with a lower charging current. This prevents the batteries from being damaged by too high a charging current. When the batteries are then fully charged, the charging current can be limited completely to zero.

[36] On the other hand, it can also be that the charge status exceeds a certain value in a downward direction. With the same example, the charge status can drop below 90%. In this case, the charging current will then be adjusted in a positive direction, namely that it assumes a higher value, and thus the batteries can be charged faster.

[37] The electrical power that the on-board charger draws from or allows from the electricity grid will also adapt based on the change in the maximum charging current. This will prevent the voltage on the electrical distribution system from becoming too high, and/or a surplus of electrical power being present on the electrical distribution system that could negatively affect the proper functioning of the connected electrical appliances.

[38] According to a preferred embodiment, the method further comprises the step of controlling the on-board charger by the battery management system to charge one or more rechargeable batteries of the composition of the one or more rechargeable batteries based on a respective state of charge.

More specifically, the on-board charger will be controlled by a controller based on data from the battery management system as explained above.

[39] In other words, the electrical power made available by activating the on-board charger on the electrical distribution system will then be used by the battery management system to charge the batteries.

This is done based on the charge status of the respective batteries and is monitored and controlled by the battery management system.

[40] According to an embodiment of the invention, the method further comprises the step of, when the electrical power corresponding to the sum of the consumer current and the maximum charging current, and the demand current if present, exceeds a maximum power of the electricity grid, limiting the predefined pressure such that the electrical consumer current is limited. As a result, the batteries will be charged less quickly in order to be able to supply the compressor with the required current.

[41] When the electrical power available from the grid is insufficient to drive both the electric motor and charge the batteries, this can be anticipated by reducing the pressure.

This will also reduce the power required by the electric motor, and therefore also the consumer current. The total required electrical power will also be reduced, while still ensuring that the batteries can be charged in a fast and efficient manner.

[42] According to a second aspect of the invention, an electrically powered mobile compressor is disclosed, the electrically powered mobile compressor comprising an electric motor for driving a compressor element for supplying a compressed gas under a predefined pressure, the compressor further comprising an electrical connection for an electricity grid, the electric motor connected to an electrical distribution device, the electrical distribution device further comprising: - an on-board charger configured to provide electrical power to the electrical distribution device from the electricity grid; and - a battery management system configured to support a power exchange between the distribution device and an assembly of one or more rechargeable batteries; - a controller configured to measure an electrical consumer current to the electric motor when active, and to determine a maximum charging current for the assembly of the one or more rechargeable batteries; the controller further configured to control the on-board charger so that an electrical power is provided from the electricity grid corresponding to the sum of the consumer current and the maximum charging current.

[43] Furthermore, the compressor may comprise a frequency controller between the electric motor and the electrical distribution device configured to convert a DC voltage from the electrical distribution device to an AC voltage of a certain frequency suitable for the electric motor. Note that this corresponds to the method of the invention already discussed.

[44] In addition, there may be an additional connection to the electrical distribution system for an electrical consumer, in which case the controller is further configured to measure an electrical demand current to the electrical consumer, and to control the on-board charger so that an electrical power is supplied from the electricity grid corresponding to the sum of the consumer current, the charging current, and the demand current.

[45] Furthermore, according to a preferred embodiment, the compressor comprises one or more rechargeable batteries.

[46] Furthermore, the controller may be configured to determine the state of charge of the composition of the one or more rechargeable batteries using the battery management system when present, and to adjust the maximum charging current when the state of charge exceeds a predefined value. Note that this follows the same approach as the method described above.

[47] The controller is further configured to control the on-board charger based on data exchanged with the battery management system for charging one or more rechargeable batteries of the composition of the one or more rechargeable batteries when present based on a respective state of charge.

[48] According to a third aspect of the invention, there is disclosed a controller configured to perform the method of the first aspect.

[49] According to a fourth aspect, a data processing system is disclosed comprising a processing unit configured to perform the method of the first aspect.

[50] According to a fifth aspect, a computer program product is disclosed comprising computer-executable instructions for performing the method of the first aspect when executed on a computer.

[51] According to a sixth aspect, a computer readable storage medium containing the computer program product according to the fifth aspect is disclosed.

Short description of the drawings

The invention will be further illustrated with reference to the figures, in which

[52] Fig. 1 schematically illustrates an electrical distribution system with an electric motor, an on-board charger, and a battery with a battery management system connected to it; and

[53] Fig. 2 schematically illustrates an electrical distribution system as in Fig. 2 with an electrical consumer connected to it; and

[54] Fig. 3 illustrates an electrically powered mobile compressor comprising the electrical distribution device as in Fig. 1 or Fig. 2; and

[55] Fig. 4 illustrates the course of the consumer current, the maximum charging current, and a discharge current in different operating modes; and

[56] Fig. 5 schematically illustrates different operating modes.

Detailed description of the embodiments

[57] The present invention will be described with reference to certain embodiments and with reference to certain drawings, but the invention is not limited thereto and is defined solely by the claims. The drawings described are only schematic and non-restrictive. In the drawings, the size of certain elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and relative sizes do not necessarily correspond to actual practical embodiments of the invention.

[58] Furthermore, the terms first, second, third and the like are used in the specification and in the claims to distinguish between like elements and not necessarily to describe a sequential or chronological order. The terms are interchangeable under appropriate circumstances and the embodiments of the invention may be practiced in sequences other than those described or illustrated herein.

[59] Furthermore, the terms above, below, over, under and the like are used in the specification and claims for illustrative purposes and not necessarily to describe relative positions. The terms so used are interchangeable under appropriate circumstances and the embodiments of the invention described herein may be practiced in orientations other than those described or illustrated herein.

[60] Furthermore, the various embodiments, although referred to as “preferred forms”, should be taken as examples of how the invention may be carried out rather than as a limitation on the scope of the invention.

[61] The term “comprising” as used in the claims shall not be construed as being limited to the means or steps listed thereafter; the term shall not exclude other elements or steps. The term shall be construed as specifying the presence of the named features, elements, steps or components referred to, but shall not exclude the presence or addition of one or more other features, elements, steps or components, or groups thereof. The scope of the expression “an apparatus comprising means A and B” shall thus not be limited to apparatuses consisting only of components A and B. The meaning is that, in relation to the present invention, only components A and B of the apparatus are listed, and the claim shall further be construed as including equivalents of these components.

[62] Fig. 1 schematically illustrates an electrical distribution system 101 with an electric motor 106, an on-board charger 103, and a battery management system 104 with a set of batteries 109 connected thereto. Furthermore, an electrical connection 108 to an external electricity grid, a controller 100, an inverter 102, a compressor element 107, and a fan 105 are illustrated.

[63] In Fig. 2, the same electrical distribution device 101 as in Fig. 1 is illustrated with an additional electrical converter 200 and an electrical connection 201, such as a socket, to which an electrical consumer can be connected.

[64] The electrical distribution board 101, also called busbar, serves as a distribution board to distribute electrical power to the consumers, such as the electric motor 106, the batteries 109 to charge them if necessary, and an electrical consumer connected to the electrical connection 200 if present. The electrical power present on the distribution board 101 is of the direct current type.

[65] Referring again to Fig. 1, the inverter 102 serves to convert the DC voltage from the distribution device 101 to a voltage suitable for the electric motor 106. The inverter 102 is, for example, a frequency converter, also called a frequency controller, inverter, or variable speed drive, VSD, when the electric motor 106 is a three-phase motor, and is suitable for connection to a DC voltage source having a value in a range of, for example, 441 to 715Vpc. The inverter may also be a DC/DC converter when the electric motor 106 is a DC motor.

[66] The electric motor 106 then drives the compressor element 107 to provide a compressed gas, usually ambient air for a mobile compressor, at a predefined pressure or flow rate. The motor is then, for example, a three-phase asynchronous motor with a power of 33kW.

[67] Although not illustrated, there may also be a mechanical coupling between the electric motor 106 and the compressor element 107. This coupling is, for example, a gearbox and ensures that the speed of the electric motor 106 is converted into a speed suitable for driving the compressor element 107.

[68] Furthermore, the compressor may be provided with a fan 105, also connected to the inverter, as a cooling system for the electric motor 106 and/or the compressor element 107. The fan 105 is, for example, energized with a voltage of 28V. Note that other cooling systems can also be provided.

It should be further understood that the current to drive the electric motor, as discussed further, also includes a current to drive the fan 105, or an alternative cooling system.

[69] Alternatively, the cooling system may include a fan connected to the distribution device 101 via its own inverter. In that case, there will be an additional demand current that must be taken into account. This own inverter may be the inverter 200, whereby the fan is connected to the available socket 201 and the fan determines the demand current.

[70] The on-board charger 103 is a device that converts power from an external electricity grid via the electrical connection 108 into a DC voltage suitable for the electrical distribution device 101. The controller 100 will determine the power that must be drawn from the electricity grid and therefore the current that will flow to the electrical distribution device 101 and will control the on-board charger 103 for this purpose. This power will be determined by the charge status of the rechargeable batteries 109, the required power for the electric motor 106, and the current for a consumer when connected to the additional inverter 200 and connection 201.

[71] Furthermore, the on-board charger 103 itself is also characterised by a power that it can draw from the electricity grid at a maximum. For example, the on-board charger 103 has a power of 22kW, whereby the connection 108 to the grid is a socket with a nominal current of 63A. This means that a maximum electrical power of 22kW can be made available on the electrical distribution device 101. In order to expand the capacity, more than one on-board charger can be provided, each with its own connection. The controller 100 will then be configured to control multiple on-board chargers.

[72] Referring again to Fig. 1, the current drawn from the mains is illustrated by reference 111. The current flowing to the electric motor is illustrated by reference 110, and the charging current to charge the batteries by reference 112. These currents 110-112 will then be in equilibrium. Referring to Fig. 2, there may then be an additional current to a consumer illustrated by reference 203. The additional connection 201 is, for example, a socket with a nominal current of 32A.

[73] In addition, there may also be multiple sets of batteries present, such as in this example the set of batteries 202 in addition to the already present 109. A set of batteries may then, for example, have a voltage range between 440V and 715V, which is in accordance with the inverter 102, allowing both devices to be connected simultaneously to the electrical distribution board 101 in a safe state.

[74] The controller 100 is configured to communicate with the on-board charger 103. Furthermore, the controller 100 communicates with the inverter 102, and the battery management system 104. If there is no inverter 102 present, i.e. in the case that the electric motor 106 is directly connected to the electrical distribution device 101, reference 102 illustrates a measuring unit to determine which current 110 the electric motor 106 needs to drive the compressor element 107. It is therefore important that the controller 100 can determine what the electrical consumer current 110 is for the electric motor 106 when active.

[75] Using the battery management system 104, the controller will also determine what the maximum charging current 112 is to be able to charge the composition of the batteries 109. A maximum charging current can be, for example, 132A. The battery management system 104 monitors the charge status of the batteries 109 and communicates to the controller 100 what the maximum charging current 112 is.

The controller 100 will then control the on-board charger on the basis of the sum of the consumer current 110 and the maximum charging current 112 in such a way that this sum corresponds to the current 111 that is drawn from the mains. With the examples mentioned above, the maximum current that can be drawn from the mains is then 205.9A. Note, however, that due to the limitation of the power of the on-board charger of 22kW, the current will be limited to 49.3A. One can then opt to connect several on-board chargers in parallel in order to be able to provide this maximum current of 205.9A.

[76] The arrangement as illustrated in Fig. 1 and Fig. 2 is then integrated in a mobile compressor 300 as illustrated in Fig. 3. Here one has a connection 108, for example a socket with a nominal current of 63A, to connect the compressor 300 to an external electricity network. Furthermore, one can also have a user interface to operate the controller 100 and/or to read the status of the various components. A first example is the charge status of the set of batteries 109, 202, as well as the remaining time required to fully charge the batteries 109, 202. Other information that can be read is the pressure of the compressed gas, the speed of the compressor element 107, and the total time during which the compressor 300 has been active.

[77] Referring to Fig. 5, the compressor 300 can also operate in different operating modes 501-503. A first operating mode 501 is the one in which the compressor operates completely autonomously, in other words, the electric motor draws all of the electric power, in this example 33kW, from the set of batteries 109, 202. This situation can occur when there is no mains electricity supply. The electric power of 33kW then corresponds to a maximum electric current of 73.9A drawn from the mains electricity supply.

[78] A second operating mode 502 is the one in which the compressor 300 is not active, but an electricity grid is available. In this case, the rechargeable batteries 109, 202 will be charged, in this example with a charging current 112 corresponding to a power of 22kW. A charging current of up to 49.3A will then flow to the battery management system to charge the batteries 109, 202.

[79] A third illustrated operating mode 503 is one in which an electrical grid is present, and in which the compressor 300 is also active. A power of 22kW can then be made available from the grid, as already explained on the basis of the power of the on-board charger 103. In this example, the electrical power for the electric motor 106 is limited to 16kW, due to a lower consumption of compressed air from the compressor so that the batteries 109, 202 can then be charged with an electrical power of 6kW while the compressor is operating at a partial load of 16kW compared to the maximum power of 33kW.

[80] Finally, with reference to Fig. 4, one has an illustration based on a set of graphs of the progression of the power flow, illustrated on the y-axis 410 in the unit kW, over time on the x-axis in the unit seconds. Here, graph 400 represents the power flow to and from the batteries 109, 202, graph 401 the electrical power drawn from the mains via connection 108, and graph 402 the power flowing to the electric motor 106 for driving the compressor element 107.

[81] On the left side of the illustration, there is an operating mode in which the electric motor 106 is driven entirely by power from the batteries 109, 202. This corresponds to operating mode 501 as illustrated in Fig. 5. On the right side, there is an illustration of an operating mode in which the electric motor 106 is driven and the batteries 109, 202 are charged. This corresponds to operating mode 503 as illustrated in Fig. 5. Finally, there is a transitional operating mode between the left and right sides of the illustration in which the electric motor 106 is driven with electrical power from both the mains via connection 108 and the set of batteries 109, 202. This corresponds to operating mode 503 as illustrated in Fig. 5.

Claims (15)

CONCLUSIONS 1.- Computer-implemented method for controlling an electrically powered mobile compressor (300) comprising a compressor element (107) driven by an electric motor (106) for delivering a compressed gas at a predefined pressure, the electric motor (106) connected to an electrical distribution device (101) for providing an electrical consumer current (110), the distribution device (101) further comprising: - an on-board charger (103) configured to provide electrical power to the electrical distribution device (101) from an electrical grid (108); and - a battery management system (104) configured to support a power exchange between the distribution device (101) and an assembly of one or more rechargeable batteries (109, 202); the method comprising the steps of: - measuring the electrical consumer current (110) to the electric motor (102) when active; and - determining a maximum charging current (112) for the composition of the one or more rechargeable batteries (109, 202) using the battery management system (104); whereby the on-board charger (103) is controlled so that an electrical power (111) is supplied from the electricity grid (108) corresponding to the sum of the consumer current (110) and the maximum charging current (112). 2. The computer-implemented method of claim 1, wherein when the electrical distribution device (101) further comprises a connection (201) for an electrical consumer, the method further comprises the steps of: - measuring an electrical demand current (203) from the electrical consumer (201); and wherein the on-board charger (103) is further controlled so that an electrical power (111) is supplied from the electricity grid (108) corresponding to the sum of the consumer current (110), the charging current (203), and the demand current (112). 3.- The computer-implemented method according to any of the preceding claims further comprising the steps of: - determining the state of charge of the composition of the one or more rechargeable batteries (109, 202) using the battery management system (104); and - adjusting the maximum charging current (112) when the state of charge exceeds a predefined value. 4. The computer-implemented method of claim 3, further comprising the step of: - controlling the on-board charger (103) by the battery management system (104) to charge one or more rechargeable batteries of the composition of the one or more rechargeable batteries (109, 202) based on a respective state of charge. 5.- The computer-implemented method according to any one of the preceding claims, wherein when the electrical power (111) corresponding to the sum of the consumer current (110) and the maximum charging current (112), and the demand current (203) when present, exceeds a maximum power of the electricity grid (108), further comprising the step of: - limiting the predefined pressure such that the electrical consumer current (110) is limited. 6.- An electrically powered mobile compressor (300) comprising an electric motor (106) for driving a compressor element (107) for delivering a compressed gas at a predefined pressure and/or flow rate, the compressor (300) further comprising an electrical connection (108) for an electricity grid, the electric motor (106) connected to an electrical distribution device (101), the electrical distribution device (101) further comprising: - an on-board charger (103) configured to provide electrical power to the electrical distribution device (101) from the electricity grid (108); and - a battery management system (104) configured to support a power exchange between the distribution device (101) and an assembly of one or more rechargeable batteries (109, 202); - a controller (100) configured to measure an electrical consumer current (110) to the electric motor (106) when active, and to determine a maximum charging current (112) for the composition of the one or more rechargeable batteries (109, 202): wherein the controller (100) is further configured to control the on-board charger (103) so that an electrical power (111) is provided from the electrical grid (108) corresponding to the sum of the consumer current (110) and the maximum charging current (112). 7.- The electrically powered mobile compressor (300) according to claim 6, further comprising a frequency controller (102) between the electric motor (106) and the electrical distribution device (101) configured to convert a DC voltage from the electrical distribution device (101) into an AC voltage with a specific frequency suitable for the electric motor (106). 8.- The electrically powered mobile compressor (300) according to any of claims 6 to 7, further comprising an inverter (200) on the electrical distribution device (101) for an electrical consumer (201), and wherein the controller (100) is further configured to measure an electrical demand current (203) to the electrical consumer (201), and to control the on-board charger (103) so that an electrical power (111) is provided from the electricity grid (108) corresponding to the sum of the consumer current (110), the charging current (112), and the demand current (203). 9. The electrically powered mobile compressor (300) according to any of claims 6 to 8, further comprising the assembly of the one or more rechargeable batteries (109, 202). 10. The electrically powered mobile compressor (300) according to any of claims 6 to 9, wherein the controller (100) is further configured to determine the state of charge of the assembly of the one or more rechargeable batteries (109, 202) using the battery management system (104), and to adjust the maximum charging current (112) when the state of charge exceeds a predefined value. 11. The electrically powered mobile compressor (300) according to claim 10, wherein the controller (100) is further configured to control the battery management system (104) to charge one or more rechargeable batteries of the composition of the one or more rechargeable batteries (109, 202) when present based on a respective state of charge. 12.- A controller (101) configured to perform the method of any one of claims 1 to 5. 13.- A data processing system comprising a processing unit configured to perform the method according to any one of claims 1 to 5. 14.- A computer program product containing instructions executable on a computer to perform the method according to any one of claims 1 to 5 when said program is executed on a computer. 15.- A computer readable storage medium containing the computer program product of claim 14.