An electrical charger for a mining / construction machine

Abstract

The disclosure relates to an electrical charger which may be denoted a first charger for a mining / construction machine The first charger (100) is connected to a power grid (200) and configured to receive a first input power (IP1) from the power grid (200) for charging at least one first battery (310). The first charger (100) is further configured to: receive a first control signal (510) from a second charger (100´) connected to the power grid (200). The first charger (100) is configured to: increase a reference power for charging the first battery (310) when the first control signal (510) is a derating signal indicating a derating of a reference power of the second charger (100´), or decrease a reference power for charging the first battery (310) when the first control signal (510) is a boosting signal indicating a boosting of a reference power of the second charger (100´). Furthermore, the disclosure also relates to a corresponding method.

Description

[0001] AN ELECTRICAL CHARGER FOR A MINING / CONSTRUCTION MACHINE

[0002] Technical Field

[0003] The disclosure relates to an electrical charger for a mining / construction machine. Furthermore, the disclosure also relates to a corresponding method.

[0004] Background

[0005] Electrified mining / construction machines and vehicles provide an opportunity to reduce the environmental footprint and create a healthier work environment in mining / construction environments. Compared to diesel machines, the electrified mining / construction machines are emission free and can hence bring considerable savings, especially for ventilation and cooling in the mining / construction environments.

[0006] The electrified mining / construction machine is therefore equipped with one or more electric loads which are powered by an on-board energy storage system (ESS) comprising a battery pack. The electric loads of the mining / construction machine may be motors, actuators, compressors, pumps, etc.

[0007] However, the battery packs need to be electrically charged so as to be able to deliver the proper electrical power to the loads of the mining / construction machine. Therefore, electrical chargers are provided in the work environment, such as construction sites and mines, for charging the battery packs of the mining / construction machines operating therein. The electrical chargers may be located at so called charging stations distributed over the work environment.

[0008] Conventional, an electrical charger is connected to a power grid and configured to receive an alternating current (AC) from the power grid. The AC from the power grid is thereafter converted to a direct current (DC). The characteristic of the DC may have to be adapted so as to be suitable for charging the batteries of a mining / construction machine. The characteristic of the DC may relate to charging voltage and charging current among other things.

[0009] Commonly, multiple electrical chargers are connected to the same power grid and configured to concurrently charge their respective mining / construction machine. Thissituation may demand a high power supply from the grid and sometime beyond the grid power capacity.

[0010] Summary

[0011] An objective of embodiments of the disclosure is to provide a solution which mitigates or solves the drawbacks of conventional solutions.

[0012] Another objective of embodiments of the disclosure is to present a charging solution with improved coordination of a plurality of independence chargers for efficient power utilization of provided power.

[0013] According to a first aspect of the disclosure, the above mentioned and other objectives are achieved with a first charger for a mining / construction machine, the first charger being connected to a power grid and configured to receive a first input power from the power grid for charging at least one first battery, the first charger further being configured to:

[0014] receive a first control signal from a second charger connected to the power grid; and

[0015] increase a reference power for charging the first battery when the first control signal is a derating signal indicating a derating of a reference power of the second charger, or

[0016] decrease a reference power for charging the first battery when the first control signal is a boosting signal indicating a boosting of a reference power of the second charger.

[0017] A charger herein may be an electrical hardware device configured to and being capable of charging one or more batteries using power received from a power grid. The charger may also have the capability of operating in a mode in which the charger is charging the power grid using a power received from one or more batteries.

[0018] The actual charging power employed by the first charger for charging the first battery may be derived from the mentioned reference power. Thus, the actual charging power may be determined based on the reference power. The actual charging power may deviate from the reference power due to hardware limitations, etc of the first charger.It may also be noted that the first and second chargers are connected to the same power grid. The number of independent chargers according to the first aspect connected to the same power source in communication with each other may be unlimited.

[0019] An advantage with the present solution is that the herein disclosed chargers are coordinated in a novel fashion by means of control signalling for synchronized derating and boosting when charging. Thus, the capacity of the power grid supplying the power for charging may be utilized in a more efficient manner in terms of available grid capacity and power sharing. Furthermore, scenarios when the grid capacity limit is reached or violated can be avoided with the present solution.

[0020] In an implementation form of a first charger according to the first aspect, the first charger is configured to:

[0021] change a slope of the reference power to a grid input voltage for charging the first battery or the power grid based on the first control signal.

[0022] An advantage with this implementation form is electrical stability may be maintained in the electrical system since the derated or boosted charging power is delivered at the same or near the same grid input voltage before derating or boosting.

[0023] In an implementation form of a first charger according to the first aspect, the first charger is configured to when charging the first battery:

[0024] increase the slope of the reference power to the grid input voltage when the first control signal is the derating signal, or

[0025] decrease the slope of the charging power to the grid input voltage when the first control signal is the boosting signal.

[0026] An advantage with this implementation form is electrical stability may be maintained in the electrical system when charging the first battery since the derated or boosted charging power is delivered at the same or near the same grid input voltage before derating or boosting.In an implementation form of a first charger according to the first aspect, the first charger is configured to when charging the first battery:

[0027] increase the slope of the reference power to the grid input voltage within a first range when the first control signal is the derating signal, or

[0028] decrease the slope of the reference power to the grid input voltage within the first range when the first control signal is the boosting signal.

[0029] An advantage with this implementation form is electrical stability may be maintained in the electrical system since the derated or boosted charging power is delivered at the same or near same grid input voltage before derating or boosting.

[0030] In an implementation form of a first charger according to the first aspect, the first charger is configured to when charging the first battery:

[0031] increase the slope of the reference power to the grid input voltage within the first range when the first control signal is the derating signal and the grid input voltage is above a first threshold value, or

[0032] decrease the slope of the reference power to the grid input voltage within the first range when the first control signal is the boosting signal, and the grid input voltage is below the first threshold value.

[0033] An advantage with this implementation form is electrical stability may be maintained in the electrical system since the derated or boosted charging power is delivered at the same or near same grid input voltage before derating or boosting.

[0034] In an implementation form of a first charger according to the first aspect, the first charger is configured to when charging the power grid:

[0035] decrease the slope of the reference power to the grid input voltage when the first control signal is the derating signal, or

[0036] increase the slope of the charging power to the grid input voltage when the first control signal is the boosting signal.

[0037] An advantage with this implementation form is electrical stability may be maintained in the electrical system when charging the power grid since the charging power deliveredto the power grid is at the same or near same grid input voltage before derating or boosting.

[0038] In an implementation form of a first charger according to the first aspect, the first charger is configured to when charging the power grid:

[0039] decrease the slope of the reference power to the grid input voltage within a second range when the first control signal is the derating signal, or

[0040] increase the slope of the reference power to the grid input voltage within the second range when the first control signal is the boosting signal.

[0041] An advantage with this implementation form is electrical stability may be maintained in the electrical system when charging the power grid since the charging power delivered to the power grid is at the same or near same grid input voltage before derating or boosting.

[0042] In an implementation form of a first charger according to the first aspect, the first charger is configured to when charging the power grid:

[0043] decrease the slope of the reference power to the grid input voltage within the second range when the first control signal is the derating signal and the grid input voltage is above a second threshold value, or

[0044] increase the slope of the reference power to the grid input voltage within the second range when the first control signal is the boosting signal, and the grid input voltage is below the second threshold value.

[0045] An advantage with this implementation form is electrical stability may be maintained in the electrical system when charging the power grid since the charging power delivered to the power grid is at the same or near same grid input voltage before derating or boosting.

[0046] In an implementation form of a first charger according to the first aspect, the first control signal indicates:

[0047] a first derating value when the first control signal is the derating signal, or a first boosting value when the first control signal is the boosting signal.An advantage with this implementation form is that a specific value of derating or boosting is carried by the first control signal. Thereby, the first charger knows exactly how much to adapt the reference power for derating or boosting in response to the reception of the first control signal.

[0048] In an implementation form of a first charger according to the first aspect, the first charger is configured to:

[0049] transmit a second control signal to the second charger, wherein the second control signal is:

[0050] a derating signal indicating a derating of a reference power of the first charger, or a boosting signal indicating a boosting of a reference power of the first charger.

[0051] An advantage with this implementation form is that duplex communication is provided in which the first charger also can inform other chargers connected to the same power grid abouts its own derating or boosting when charging. Since the second charger(s) is connected to the same power grid further coordination of independent chargers is provided for improved utilization of the power capacity of the power grid.

[0052] In an implementation form of a first charger according to the first aspect, the second control signal indicates:

[0053] a second derating value when the second control signal is the derating signal, or a second boosting value when the second control signal is the boosting signal.

[0054] An advantage with this implementation form is that also the second charger will be informed about specific values of derating or boosting of the first charger. Thereby, the second charger knows exactly how much to adapt its own reference power for derating or boosting.

[0055] In an implementation form of a first charger according to the first aspect, the first charger is configured to:

[0056] determine the second control signal based on one or more measurements at the first charger and / or at the power grid.An advantage with this implementation form is that the first charger can detect whether derating or boosting is required or possible based on the one or more measurements.

[0057] In an implementation form of a first charger according to the first aspect, the one or more measurements comprise any of electrical measurements and temperature measurements.

[0058] These types of measurements give relevant information whether derating or boosting is required or possible.

[0059] In an implementation form of a first charger according to the first aspect, the first charger is configured to:

[0060] determine the second control signal further based on one or more fault indications of the first charger.

[0061] An advantage with this implementation form is that also fault indications are relevant for determining whether derating or boosting is required or possible.

[0062] In an implementation form of a first charger according to the first aspect, the first charger is configured to:

[0063] determine the second control signal further based on an operator command.

[0064] An advantage with this implementation form is that the operator can decide which chargers to prioritize.

[0065] In an implementation form of a first charger according to the first aspect, the reference power for charging the first battery is a reactive reference power injected or absorbed from the power grid.

[0066] An advantage with this implementation form is that with reactive power better voltage support is provided in the electrical system.In an implementation form of a first charger according to the first aspect, the first charger is connected to a first battery energy storage systems, BESS, and wherein the first charger is configured to:

[0067] increase a reference power for charging the first BESS when the first control signal is the derating signal, or

[0068] decrease a reference power for charging the first BESS when the first control signal is the boosting signal.

[0069] An advantage with this implementation form is that also the power capacity of the BESS can be utilized in a more efficient manner in the same way as for the power grid.

[0070] In an implementation form of a first charger according to the first aspect, the first charger and the second charger are connected to the power grid via a common electrical coupling point or via separate electrical coupling points.

[0071] An advantage with this implementation form is that electrical coordination between chargers arranged at different locations can be achieved.

[0072] In an implementation form of a first charger according to the first aspect, the first charger and the second charger are connected to the power grid via a common substation.

[0073] According to a second aspect of the disclosure, the above mentioned and other objectives are achieved with a charging system comprising two or more chargers according to embodiments of the invention.

[0074] According to a third aspect of the disclosure, the above mentioned and other objectives are achieved with a method for a first charger, the first charger being connected to a power grid and configured to receive a first input power from the power grid for charging at least one first battery, the method comprising:

[0075] receiving a first control signal from a second charger connected to the power grid; andincreasing a reference power for charging the first battery when the first control signal is a derating signal indicating a derating of a reference power of the second charger, or

[0076] decreasing a reference power for charging the first battery when the first control signal is a boosting signal indicating a boosting of a reference power of the second charger.

[0077] The method may be adapted in accordance with the above-mentioned embodiments of the first charger according to the first aspect. The advantages of the method are the same as the advantages of the corresponding embodiments of the first charger according to the first aspect.

[0078] According to further aspects of the present disclosure, the herein described methods are implemented by use of computer program products comprising instructions which, when the programs are executed by a computer, such as e.g., a control unit, cause the computer to carry out the steps of the methods according to any one of the herein described embodiments.

[0079] Further applications and advantages of embodiments of the disclosure will be apparent from the following detailed description.

[0080] Brief Description of the Drawings

[0081] The appended drawings are intended to clarify and explain different embodiments of the disclosure, in which:

[0082] Fig. 1 shows a first charger according to embodiments of the disclosure;

[0083] Fig. 2 shows a first charger with duplex communication capability according to embodiments of the disclosure;

[0084] Fig. 3 shows a first charger connected to a BESS according to embodiments of the disclosure;

[0085] Fig. 4 shows a charging system according to embodiments of the disclosure; Fig. 5 illustrates when a first charger is charging a load of a mining / construction machine according to embodiments of the disclosure;

[0086] Figs. 6 to 8 illustrate change of power-voltage slope when the first battery is charged by the first charger according to embodiments of the disclosure;Figs. 9 to 11 illustrate change of power-voltage slope when the power grid is charged by the first charger according to embodiments of the disclosure;

[0087] Fig. 12 shows a flow chart of a method according to embodiments of the disclosure; and

[0088] Fig. 13 illustrates different examples of mining / construction machine.

[0089] Detailed Description

[0090] When multiple separate chargers are connected to a common power grid via the same charging station or substation, grid capacity limits will be imposed when charging multiple batteries of the same or different machines. It is likely that multiple chargers will not be able to operate in full power, all together and at the same time in such charging architecture. This is especially true for high power rated chargers connected to the same power grid. With bidirectional power flow, the chargers will also participate in grid support i.e. , a flow of power from the chargers to the power grid. Thus, the chargers will share the grid capacity to charge or share the power requirement to discharge based on ratings and requested power references.

[0091] From the above, the issue of efficient utilization of charging power is raised. The present disclosure therefore provides a solution for efficient utilization of common power shared among a plurality of chargers. It is considered that when a charger is charging in a derated mode, e.g., due to grid condition or temperature, extra power headroom available within the power grid capacity can be used by another charger which is not operating at the rated power due to grid capacity limits. The analogous reasoning can be applied when a charger is charging in a boosted / boost mode, i.e., another charger will have to derate its own charging.

[0092] Fig. 1 shows a first charger for a mining / construction machine 300 according to embodiments of the disclosure. The first charger 100 is connected to a power grid 200 and configured to receive a first input power IP1 from the power grid 200 for charging at least one first battery 310. The power grid 200 may be any suitable power grid configured to provided power to the first charger such as an alternating current (AC) power grid. The first charger 100 may comprise an output circuit connected to one or more first batteries 310 and configured to charge the one or more first batteries 310 when operating in a charging mode.The first charger 100 is further configured to receive a first control signal 510 from a second charger 100' connected to the same power grid 200. The first control signal 510 may be a wired or a wireless communication signal conforming to standardized communication protocols. Thus, the first 100 and second 100' chargers may be communicatively connected to each other by means of a communication interface in this respect. The communication interface may be defined according to conventional standards.

[0093] The disclosed first control signal 510 is either a derating signal or a boosting signal. Depending on whether derating or boosting is indicated by the first control signal 510, the first charger 100 may act in two different ways when charging the first battery 310. In a first case, the first charger 100 is configured to increase a reference power for charging the first battery 310 when the first control signal 510 is a derating signal indicating a derating of a reference power of the second charger 100'; or in a second case decrease a reference power for charging the first battery 310 when the first control signal 510 is a boosting signal indicating a boosting of a reference power of the second charger 100'.

[0094] Thereby, the first charger 100 can use surplus power capacity of the power grid 200 for boosting its charging of the first battery 310 when the second charger indicates derating since the second charger 100' will lower its power use in such cases. Correspondingly, the first charger 100 will derate its own charging of the first battery 310 when the second charger 100' indicates boosting so that surplus power can be used by the second charger 100' in boosting mode.

[0095] The actual reference power applied by the first charger 100 may be calculated from demanded power taking into consideration of power sharing as well deratings. In this respect also properties and characteristics of the hardware in the first charger 100 may have to be considered.

[0096] It may be noted that the terms “first” and “second” in the expressions “first charger” and “second charger” are labels only and non-limiting in any sense. The same applies for the expressions “first control signal” and “second control signal” in this context.The first charger 100 may comprise a controller 110 configured to control the functions of the first charger 100. The controller 110 therefore comprises the necessary elements, components and devices for performing its tasks such as processor, control algorithm, memory, communication lines, wired and / or wireless communication interfaces, transceivers, power feed lines, power supply, etc. Thus, the controller 110 may receive input such as data, parameters and measurements, and output control signals based on the input data used in a control algorithm. The control signals are used to control the different functions of the first charger 100. The input to the controller 110 is described more in the following disclosure.

[0097] In embodiments of the disclosure, the first control signal 510 further indicates a first derating value d1 when the first control signal 510 is the derating signal, or a first boosting value b1 when the first control signal 510 is the boosting signal. These values may be actual values or delta values. Actual values may be given as an absolute power value e.g., 10, 20, 100, 500, or 1000 kW by with derating or boosting is applied by the first charger 100. However, when delta values are indicated the actual values may be derived based on the delta values. The delta value gives a value in relation to a previous set value and represent the difference to the previous value.

[0098] The first charger 100 upon receiving the first control signal 510 derives the first derating value d1 or the first boosting value b1. If the first derating value d1 is indicated, the first charger 100 can boost its charging i.e., charging power, with an exact amount derived from the first derating value d1 e.g., raise its charging power equal or 500 kW or set it to 1500 kW. Correspondingly, if the first boosting value b1 is indicated, the first charger 100 can derate its charging with an exact amount derived from the first boost value b1 e.g., lower its charging power with 500 kW or set it to 500 kW.

[0099] The indication of derating or boosting may be performed using a bit flag which result in low overhead in the communication between the chargers of the herein disclosed charging system. For example, “0” may indicate derating and “1” boosting, or vice versa. When the derating value (d1 , d2) or boosting (b1 , b2) value also is indicated by control signalling, mentioned values may be indicated with a bit sequence directly representing the derating or boosting value or representing an index valuecorresponding to a predetermined value. Such predetermined value may be given by a table comprising an association between index and derating or boosting value. The number of bits in the bit sequence needed for control signalling may depend on the range and the granularity of these values.

[0100] Fig. 2 shows a first charger 100 with duplex communication capability according to embodiments of the disclosure implying that the first charger 100 may also transmit control signals to other chargers of the herein disclosed charging system. In these embodiments of the disclosure, the first charger 100 may inform one or more second chargers whether the first charger 100 is derating or boosting when charging one or more first batteries 310. Hence, the first charger 100 may be configured to transmit a second control signal 520 to the second charger 100', where the second control signal 520 is a derating signal indicating a derating of a reference power of the first charger 100, or a boosting signal indicating a boosting of a reference power of the first charger 100. Thereby, the second charger 100' can adapt its charging of one or more second batteries to the behaviour of the first charger 100 for improved utilization of the power grid capacity.

[0101] When derating is signalled to the second charger 100' in the second control signal 520, the second charger 100' upon reception of the second control signal 520 can boost its charging since there will be a surplus power capacity, e.g., in the grid, due to the derating of the first charger 100. However, when boosting is signalled to the second charger 100' in the second control signal 520, the second charger 100' will derate its charging so as to adapt to the boost charging by the first charger 100.

[0102] Also, the second control signal 520 may indicate a derating value or a charging value indicating specific values of derating or boosting. Thus, the second control signal 520 may further indicate a second derating value d2 when the second control signal 520 is the derating signal, or a second boosting value b2 when the second control signal 520 is the boosting signal. The second charger 100' can use the second derating and boosting values in the same way as the first charger 100 uses the first derating value d1 and the first boosting value b1. That is, the second charger 100' will know the exact amount of power to derate or boost when receiving the second control signal 520. The second derating value d2 and the second boosting value b2 may be indicated usingthe same principles as the indication of the first derating value d1 and the first boosting value b1.

[0103] In embodiments of the disclosure, the first charger 100 will determine whether derating or boosting is required or possible in a given charging situation or scenario. In this determination or decision procedure, the second derating value d2 and the second boosting value b2 may also be computed using the same input as for determining if either derating or boosting will be performed.

[0104] There may be a number of considerations when deciding if the first charger 100 will derate or boost its charging of first batteries. Thus, in embodiments of the disclosure, the first charger 100 determines the second control signal 520 based on one or more measurements at the first charger 100 and / or at the power grid 200. Both local and remote measurements from the perspective of the first charger 100 may therefore be used for deciding either derating or boosting of charging the first battery 310. The remote measurements may be measurements at the power grid 200 but also at a substation or a common connection point for multiple chargers forming a charging system.

[0105] The one or more measurements may comprise electrical measurements and / or temperature measurements in embodiments of the disclosure.

[0106] The electrical measurements may be voltage or current measurements. These measurements give information about the power capacity and thus may form the basis for decision about derating or boosting.

[0107] The temperature measurements give information about changes in the maximum possible current carrying ability. Thus, also this information may be used to form the basis for decision about derating or boosting. These temperature measurements may be provided with one or more temperature sensors provided to the controller 110 of the first charger 100.

[0108] Other aspects to be considered when determining the second control signal 520 are fault indications of the first charger 100 and also operator commands.The fault indications of the first charger 100 will give information about the functioning or capacity of the first charger 100. If a fault is detected, the charging capacity is partially or completely reduced and thus the first charger 100 will therefore have to derate or stop its charging.

[0109] The operator commands are instructions from the operator in charge of the mining / construction machines e.g., in a mine or a construction area. The operator may prioritize some mining / construction machines before others. Thus, the use of grid capacity for charging based on priority may override other charging principles used when scheduling charging of batteries.

[0110] Fig. 3 shows a charger connected to a BESS 210 according to embodiments of the disclosure. Thus, the first charger 100 receives power from both the power grid 200 and the BESS 210 in such embodiments of the disclosure. The BESS 210 can be handled in the same way as the first battery 310. In other words, the first charger 100 may be configured to increase a reference power for charging the first BESS 210 when the first control signal 510 is the derating signal or decrease a reference power for charging the first BESS 210 when the first control signal 510 is the boosting signal.

[0111] The topology or architecture of the charging system comprising a plurality of chargers according to embodiments of the invention may vary. The charging system may comprise two or more separate chargers connected to the same power grid 200 as shown in Fig. 4. Thus, the common power grid 200 is configured to supply power to the two or more chargers. The charging system may also comprise one or more controllers configured to control the separate chargers of the charging system. The controlling of the chargers may be distributed or centralised. Fig. 4 shows the example of distributed control in which a controller 110 controls the first charger 100 by means of control lines or interfaces in which control signals are carried. Correspondingly, the second charger 100' comprises its own controller (now shown) configured to control the second charger 100'. In a centralized solution, a central controller may be configured to control the separate chargers of the charging system.Furthermore, the two or more chargers 100, 100' may be directly connected to the power grid 200 in an example of the disclosure. However, in other examples, the two or more chargers 100, 100' may be connected to the power grid 200 via a common substation 210. Commonly, a power grid 200 is connected to one or more primary substations. Onsite power generation, renewable power generation and BESS are often located at the primary substation. Usually, there are outgoing feeders / electrical lines inside mines and construction sites forming the electrical network from the primary substation, and charging stations are likely connected at different location in the network through a secondary substation which may comprise transformers, breakers, electrical protection, etc.

[0112] Moreover, the two or more chargers 100, 100' may be connected to the power grid 200 via a common electrical coupling point 220 (Fig. 4a) or via separate electrical coupling points 220, 220' (Fig. 4b) depending on the application.

[0113] Fig. 5 illustrates when a first charger 100 according to embodiments of the invention is charging a battery 310 of a mining / construction machine 300 via a power charging interface. The first charger 100 receives input power IP1 from a power grid 200 and possibly also power from a BESS 210. If needed the received power is converted by the first charger 100 e.g., from AC to DC or from a first DC to a second DC before supplied to the first battery 310 for charging.

[0114] In embodiments of the disclosure, a slope of the reference power to a grid input voltage (also called power-voltage curve) may be adapted so as to maintain stability in the system. In other words, the first charger 100 may be configured to change a slope of the reference power to a grid input voltage for charging the first battery 310 or the power grid 200 based on the first control signal 510. Thus, the grid input voltage may be adapted to a new voltage level when the first control signal 510 indicates derating or boosting. In this respect two main cases may be identified, i.e., when the first charger 100 is charging the first battery 310 or when the first charger 100 instead is charging the power grid 200. Thus, the power may flow from the first charger 100 to the first battery 310 or in an opposite direction from the first charger 100 to the power grid 200. The slope may mathematically be interpreted as the absolute value of the derivate ofe.g. a linear function expressing the relationship between power and voltage. More specifically, the voltage may be expressed as a function of the power.

[0115] Figs. 6 to 8 illustrate different embodiments of the disclosure when the first battery 310 is charged by the first charger 100. These Figs, show the concept of adapting the previous mentioned slope for the first charger 100 when the first battery 310 is charged. Generally, the first charger 100 when charging the first battery 310 increases the slope of the reference power to the grid input voltage when the first control signal 510 is the derating signal, i.e., the second charger 100' is operating in derating mode; and decrease the slope of the charging power to the grid input voltage when the first control signal 510 is the boosting signal, i.e., the second charger 100' is operating in boosting mode. Increasing the slope is understood to mean that the slope is made steeper while decreasing the slope has the reverse meaning, i.e., that the slope is made less steep or flatter. Sometimes, the slope can be understood as a gradient, an incline, etc.

[0116] The example is illustrated in Fig. 6 when the first control signal 510 indicates boosting at the second charger 110'. Thus, during a charging mode of the first charger 100, the demanded reference power is P1 at voltage Vpcc, and the first charger 100 is operating in point 1. Since the second charger 100' is operating in its boosting mode, the power reference for the first charger 100 is reduced to PT at voltage Vpcc’ in point 2. Thus, the slope of the power-voltage curve is changed so as to move the charging power from P1 to PT from voltage Vpcc’ to Vpcc in point 3.

[0117] In embodiments of the disclosure, a first range is also considered when changing the slope. In other words, the first charger 100 when charging the first battery 310 may be configured to increase the slope of the reference power to the grid input voltage within a first range when the first control signal 510 is the derating signal; and decrease the slope of the reference power to the grid input voltage within the first range when the first control signal 510 is the boosting signal. The first range is the range within the slope is allowed to change. A too large change in the slope may namely result in electrical instability in the electrical system as there will be a too large deviation of power for a change in voltage, or vice versa when a too large change in voltage will result in a large change in power output.To trigger the change of the slope of the reference power to the grid input voltage, a first threshold value may be used. More specifically, the first charger 100 when charging the first battery 310 will increase the slope of the reference power to the grid input voltage within the first range when the first control signal 510 is the derating signal and the grid input voltage is above a first threshold value; and decrease the slope of the reference power to the grid input voltage within the first range when the first control signal 510 is the boosting signal and the grid input voltage is below the first threshold value. Thus, a triggering mechanism is provided by which the first charger 100 knows when to change the slope for stability based on threshold values Thus, the value of the first threshold value should be designed such that change in the slope is trigged when needed to maintain stability but without excessive number of changes during a time period which may also result in instability.

[0118] Fig. 7 shows the slopes for the first charger 100 and the second charger 100' when they are connected to the power grid 200 via a common or the same electrical coupling point 220. During a charging mode, the first charger 100 (denoted Charger 1) is operating in point 1 and the demanded reference power is P1 at voltage Vpcc. Due to the derating mode of the first charger 100, the reference power for the first charger 100 is reduced to PT at voltage Vpcc’ in point 2. Thus, the power-voltage curve is changed, i.e. , the slope is decreased, to move power PT from voltage Vpcc’ to Vpcc in point 3. However, for the second charger 100' (denoted Charger 2), the power reference P2 is changed from point 4 to point 5 to utilize the grid capacity due to reduction in the reference power used by the first charger 100. The reference power for the second charger 100' is therefore changed from P2 to P2’ at voltage Vpcc”. Thus, the powervoltage curve is changed to achieve power P2’ at voltage Vpcc in point 6 for the second charger 100'.

[0119] Fig. 8 shows the slopes for the first charger 100 and the second charger 100' when they are connected to the power grid 200 via separate electrical coupling points 220, 220'. During a charging mode, the demanded reference power is P1 at voltage Vpcc and the first charger 100 is operating in point 1. Due to the derating mode, the reference power for the first charger 100 is reduced to PT at voltage VpccT in point 2. Thus, the power-voltage curve is changed from PV1 to PVT to move power PT from voltage VpccT to voltage Vpccl in point 3. However, for the second charger 100', thereference power P2 is changed from point 4 to point 5 to utilize the grid capacity due to reduction in used power by the first charger 100. The reference power for the second charger 100' is hence changed from power P2 at voltage Vpcc2 to power P2’ at voltage Vpcc2’. Thus, the power-voltage curve is changed from PV2 to PV2’ to achieve the power P2’ at voltage Vpcc2 in point 6 for the second charger 100'.

[0120] Fig. 9 to 11 illustrate the embodiments when the power grid 200 instead of the first battery 310 is charged by the first charger 100. That is, when the power flows from the first charger 100 to the power grid 200 as previously mentioned. Generally, the first charger 100 when charging the power grid 200 decreases the slope of the reference power to the grid input voltage when the first control signal 510 is the derating signal i.e. , the second charger 100' is operating in derating mode; and increases the slope of the charging power to the grid input voltage when the first control signal 510 is the boosting signal, i.e., the second charger 100' is operating in boosting mode.

[0121] Fig. 9 shows that during the charging mode of the first charger 100, the demanded reference power is P1 at voltage Vpcc and the first charger 100 is operating in point 1. Due to derating mode of the first charger 100, the reference power is reduced to PT at voltage Vpcc’ in point 2. Thus, the power-voltage curve is changed from power PV1 to PVT to move power PT from voltage Vpcc’ to voltage Vpcc in point 3.

[0122] As previously mentioned, a range and a threshold value, denoted a second range and a second threshold value, respectively, may be employed when adapting the slope(s). This also applies for the cases when the first charger is charging the power grid 200. Thus, the first charger 100 decreases / increases the slope of the reference power to the grid input voltage within a second range. The second range can be selected to ensure that the voltage is within regulation limit to uphold stability in the system. Generally, the second range and the second threshold value can be used in the same manner as the first range and the first threshold value. Usually, the second range is different to the first range, i.e., a larger or smaller range. The same goes for the second threshold value, i.e., the second threshold value is larger or smaller than the first threshold value.Thus, the first charger 100 may also decrease / increase the slope of the reference power to the grid input voltage within a second range when the first control signal 510 is above or below a second threshold value.

[0123] Fig. 10 shows the slopes for the first charger 100 and the second charger 100' when they are connected to the power grid 200 via a common or the same electrical coupling point 220. During the charging mode of the first charger 100, the demanded reference power is P1 at voltage Vpcc and the first charger 100 is operating in point 1. Due to derating mode of the first charger 100, the reference power is reduced to PT at voltage Vpcc’ in point 2. Thus, the power-voltage curve is changed to move the power PT at voltage from voltage Vpcc’ to voltage Vpcc in point 3. However, for the second charger 100', the reference power P2 is changed from point 4 to point 5 to utilize the grid capacity due to reduction in power used by the first charger 100. The reference power is hence changed from P2 to P2’ at voltage Vpcc”. Thus, the power-voltage curve is changed to achieve the power P2’ at voltage Vpcc in point 6.

[0124] Fig. 11 shows the slopes for the first charger 100 and the second charger 100' when they are connected to the power grid 200 via separate electrical coupling points 220, 220'. During the charging mode of the first charger 100, the demanded reference power is P1 at voltage Vpccl and the first charger 100 is operating in point 1. Due to derating of the first charger 100, the reference power is reduced to PT at voltage VpccT in point 2. Thus, the power-voltage curve is changed to move the power PT to voltage Vpccl from voltage VpccT in point 3. However, for the second charger 2, the reference power P2 is changed from point 4 to point 5 to utilize the grid capacity due to derating mode of the first charger 100. The reference power is hence changed from P2 at voltage Vpcc2 to P2’ at voltage Vpcc2’. Thus, the power-voltage curve is changed to achieve power P2’ at voltage Vpcc2 in point 6.

[0125] Fig. 12 shows a flow chart of a method 400 according to embodiments of the disclosure. As aforementioned, the first charger 100 is connected to a power grid 200 and configured to receive a first input power IP1 from the power grid 200 for charging at least one first battery 310. The method 400 comprises: receiving 402 a first control signal 510 from a second charger 100' connected to the power grid 200; and increasing 404 a reference power for charging the first battery 310 when the first control signal510 is a derating signal indicating a derating of a reference power of the second charger 100', or decreasing 406 a reference power for charging the first battery 310 when the first control signal 510 is a boosting signal indicating a boosting of a reference power of the second charger 100'.

[0126] Embodiments of the method 400 may fully correspond to all embodiments of the first charger 100 herein disclosed. Thus, the first charger 100 comprises one or more controllers 110 arranged / configured / programmed with instruction to carry out the method 400.

[0127] Fig. 13 illustrates examples of a mining / construction machine 300 that may be used with the first charger 100 for charging the batteries of the mining / construction machine 300. The mining / construction machine 300 may be any type of electrified machine or vehicle used in a mining and / or construction environment / site such as e.g., a drill rig, a truck, a loader, a digging machine, etc. With reference to Fig. 13, the mining / construction machine 300 may e.g., be a drill rig, a loading, hauling and dumping (LHD) machine or a mine truck but is not limited thereto.

[0128] Finally, it should be understood that the disclosure is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

CLAIMS1. A first charger (100) for a mining / construction machine (300), the first charger (100) being connected to a power grid (200) and configured to receive a first input power (IP1) from the power grid (200) for charging at least one first battery (310), the first charger (100) further being configured to:receive a first control signal (510) from a second charger (100') connected to the power grid (200); andincrease a reference power for charging the first battery (310) when the first control signal (510) is a derating signal indicating a derating of a reference power of the second charger (100'), ordecrease a reference power for charging the first battery (310) when the first control signal (510) is a boosting signal indicating a boosting of a reference power of the second charger (100').

2. The first charger (100) according to claim 1 , configured to:change a slope of the reference power to a grid input voltage for charging the first battery (310) or the power grid (200) based on the first control signal (510).

3. The first charger (100) according to claim 2, configured to when charging the first battery (310):increase the slope of the reference power to the grid input voltage when the first control signal (510) is the derating signal, ordecrease the slope of the charging power to the grid input voltage when the first control signal (510) is the boosting signal.

4. The first charger (100) according to claim 3, configured to when charging the first battery (310):increase the slope of the reference power to the grid input voltage within a first range when the first control signal (510) is the derating signal, ordecrease the slope of the reference power to the grid input voltage within the first range when the first control signal (510) is the boosting signal.

5. The first charger (100) according to claim 4, configured to when charging the first battery (310):increase the slope of the reference power to the grid input voltage within the first range when the first control signal (510) is the derating signal and the grid input voltage is above a first threshold value, ordecrease the slope of the reference power to the grid input voltage within the first range when the first control signal (510) is the boosting signal, and the grid input voltage is below the first threshold value.

6. The first charger (100) according to any one of claim 2 to 5, configured to when charging the power grid (200):decrease the slope of the reference power to the grid input voltage when the first control signal (510) is the derating signal, orincrease the slope of the charging power to the grid input voltage when the first control signal (510) is the boosting signal.

7. The first charger (100) according to claim 6, configured to when charging the power grid (200):decrease the slope of the reference power to the grid input voltage within a second range when the first control signal (510) is the derating signal, orincrease the slope of the reference power to the grid input voltage within the second range when the first control signal (510) is the boosting signal.

8. The first charger (100) according to claim 7, configured to when charging the power grid (200):decrease the slope of the reference power to the grid input voltage within the second range when the first control signal (510) is the derating signal and the grid input voltage is above a second threshold value, orincrease the slope of the reference power to the grid input voltage within the second range when the first control signal (510) is the boosting signal, and the grid input voltage is below the second threshold value.

9. The first charger (100) according to any one of the preceding claims, wherein the first control signal (510) indicates:a first derating value (d1) when the first control signal (510) is the derating signal, ora first boosting value (b1 ) when the first control signal (510) is the boosting signal.

10. The first charger (100) according to any one of the preceding claims, configured to:transmit a second control signal (520) to the second charger (100'), wherein the second control signal (520) is:a derating signal indicating a derating of a reference power of the first charger (100), ora boosting signal indicating a boosting of a reference power of the first charger (100).

11. The first charger (100) according to claim 10, wherein the second control signal (520) indicates:a second derating value (d2) when the second control signal (520) is the derating signal, ora second boosting value (b2) when the second control signal (520) is the boosting signal.

12. The first charger (100) according to claim 10 or 11, configured to:determine the second control signal (520) based on one or more measurements at the first charger (100) and / or at the power grid (200).

13. The first charger (100) according to claim 12, wherein the one or more measurements comprise any of electrical measurements and temperature measurements.

14. The first charger (100) according to any one of claims 10 to 13, configured to: determine the second control signal (520) further based on one or more fault indications of the first charger (100).

15. The first charger (100) according to any one of claims 10 to 14, configured to:determine the second control signal (520) further based on an operator command.

16. The first charger (100) according to any one of the preceding claims, wherein the reference power for charging the first battery (310) is a reactive reference power injected or absorbed from the power grid (200).

17. The first charger (100) according to any one of the preceding claims, wherein the first charger (100) is connected to a first battery energy storage systems, BESS, (210) and wherein the first charger (100) is configured to:increase a reference power for charging the first BESS (210) when the first control signal (510) is the derating signal, ordecrease a reference power for charging the first BESS (210) when the first control signal (510) is the boosting signal.

18. The first charger (100) according to any one of the preceding claims, wherein the first charger (100) and the second charger (100') are connected to the power grid (200) via a common electrical coupling point (230) or via separate electrical coupling points (230, 230').

19. The first charger (100) according to any one of the preceding claims, wherein the first charger (100) and the second charger (100') are connected to the power grid (200) via a common substation (220).

20. A method (400) for a first charger (100), the first charger (100) being connected to a power grid (200) and configured to receive a first input power (IP1) from the power grid (200) for charging at least one first battery (310), the method (400) comprising:receiving (402) a first control signal (510) from a second charger (100') connected to the power grid (200); andincreasing (404) a reference power for charging the first battery (310) when the first control signal (510) is a derating signal indicating a derating of a reference power of the second charger (100'), ordecreasing (406) a reference power for charging the first battery (310) when the first control signal (510) is a boosting signal indicating a boosting of a reference power of the second charger (100').

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