Energy source system for mining and / or construction machines

Abstract

A method of controlling the operation of an electrical power unit (130) in an electric mining and / or construction machine (2) is provided, wherein the electrical power unit (130) is connectable to a charging station (20) and comprises at least a first electrical power source (132) and a second electrical power source (134). The method comprises the following steps: determining a status of the first and second electrical power sources (132, 134), and interconnecting the first and second electrical power sources (132, 134) depending on any of the following: the status of the first and second electrical power sources (132, 134), a voltage of the charging station (20) or a status of the electric mining or construction machine (2). Problems associated with the charging and operation of electrical mining and / or construction machines with internal electrical energy sources are thereby eliminated or at least mitigated.

Description

113458PC1ENERGY SOURCE SYSTEM FOR MINING AND / OR CONSTRUCTION MACHINESTechnical field

[0001] The present invention relates generally to electrical energy sources for mining and / or construction machines and more particularly to a method for controlling the operation of an electrical power unit in an electric mining and / or construction machine as well as such an electrical power unit and an electric mining and / or construction machine with such an electrical power unit.Background art

[0002] Mining and / or construction machines, such as rock drilling rigs, are used for several purposes, such as exploration drilling, which aims to identify the location and quality of a mineral, and production mining and quarrying, used in the production-cycle for mining or construction. Other application areas are road construction and structural construction.

[0003] Traditionally, mining and / or construction machines have been driven by combustion engines. However, in recent years, growing environmental concerns have driven the mining industry to reducing or phasing out the traditional combustion engines to reduce and eventually stop the emission of greenhouse gases from fossil fuels.

[0004] In the mining industry the solution is focused on electrification of the machine park. Electrification has some challenges, mainly in the capacity of today’s electric batteries, especially in a rock drilling rig, where the demands for power and energy are high during rock drilling. This is solved in that the rock drilling rig can be connected to an external electrical network when performing its rock drilling work cycle.

[0005] As an alternative to being connected to an external electrical network, a mining and / or construction machine may comprise an internal energy source, such113458PC2 as an electric battery, which powers the mining and / or construction machine during operation thereof.

[0006] The electrification of mining and / or construction machines with internal energy sources requires arrangements for charging the internal energy sources, i.e. , charging stations provided on the mining site. The charging itself results in different aspects that must be solved, such as available power for charging stations, voltage levels adapted for the internal energy sources etc.

[0007] There are different standards for the nominal voltage of batteries used in the mining industry, such as 800 V and 1500 V. The operation and charging of the batteries are made more difficult to handle in an environment lacking a single standard.

[0008] There is therefore a need for a solution mitigating or eliminating the problems associated with the charging and operation of electrical mining and / or construction machines with internal electrical energy sources.Summary of invention

[0009] An object of the present invention is to provide a method of controlling the operation of an electrical power unit in an electric mining and / or construction machine wherein the above-mentioned problems are eliminated or at least mitigated. Another object is to provide an electrical power unit and an electric mining and / or construction machine with such electrical power unit operating according to the method.

[0010] According to a first aspect of the invention, a method of controlling the operation of an electrical power unit in an electric mining and / or construction machine is provided, the electrical power unit being connectable to a charging station and comprising at least a first electrical power source and a second electrical power source, the method comprising the following steps: determining a status of the first and second electrical power sources, and interconnecting the first and second electrical power sources depending on any of the following: the113458PC3 status of the first and second electrical power sources, a voltage of a charging station or a status of the electric mining or construction machine.

[0011] In a preferred embodiment, the method comprises the steps of connecting the electrical power unit to the charging station, determining the voltage of the charging station, and interconnecting the first and second electrical power sources depending on the voltage of the charging station.

[0012] In a preferred embodiment, the step of interconnecting the first and second electrical power sources comprises connecting the first and second electrical power sources in parallel. Alternatively, the first and second electrical power sources comprises connecting the first and second electrical power sources in series.

[0013] In a preferred embodiment, the status of the electrical power sources is any of the following: state of charge, state of health, degradation and failure.

[0014] In a preferred embodiment, the method comprises the additional step of connecting the electrical power unit to a bus of an electric drive system of the electric mining and / or construction machine, wherein the status comprises a voltage of the bus. It is then preferred to provide a DC / DC power converter between the first electrical power source and the bus. Preferably, in this case the method comprises the additional steps of determining the voltage of the bus, connecting the first and second electrical power sources in series, and controlling the DC / DC power converter to provide a predetermined voltage to the bus.

[0015] In a preferred embodiment, when the electrical power unit 130 is disconnected from the charging station, the first and second electrical power sources are connected in series.

[0016] In a preferred embodiment, the method comprises the following steps: disconnecting the electrical power sources from the bus, connecting the electrical power sources to the charging station, determining a state of charge of the electrical power sources, and if the state of charge of the electrical power sources is above a predetermined threshold, connecting the electrical power sources in113458PC4 series, and if the state of charge of the electrical power sources is below the predetermined threshold, connecting the electrical power sources in parallel.

[0017] In a preferred embodiment, the method comprises the additional step of providing a DC / DC power converter between the electrical power unit and the bus.

[0018] According to a second aspect of the invention, an electrical power unit for an electrical mining and / or construction machine is provided, the electrical power unit comprising a first and a second energy source, the power unit comprising an interface unit connected to the first and second energy sources and connectable to a charging station and to a bus of an electric drive system of the electrical mining and / or construction machine, wherein the interface unit is adapted to connect the first and second energy sources in series or in parallel, depending on an operating condition.

[0019] In a preferred embodiment, the energy sources are any of the following: an electric battery, a super capacitor, and a fuel cell.

[0020] According to a third aspect of the invention, an electrically powered mining and / or construction machine is provided comprising a power converter, the input of which is connectable to an external power source, an electric drive unit, a bus interconnecting an output of the power converter and an input of the electric drive unit, an electrical power unit according to the invention connected to the bus and connectable to a charging station, and a control unit adapted to control the electrical power unit to perform the method according to the invention.

[0021] According to a fourth aspect of the invention, a non-transitory computer- readable source medium is provided that stores a program configured to execute the method according to the invention in an electrically powered mining and / or construction machine according to the invention.

[0022] According to a third aspect of the invention, a computer program product is provided comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to the invention113458PC5 in an electrically powered mining and / or construction machine according to the invention.Brief description of drawings

[0023] The invention is now described, by way of example, with reference to the accompanying drawings, in which:Fig. 1 shows a schematic view of a mining and / or construction machine in the form of a surface drilling rig that is electrified and has the possibility of connecting to an electrical network;Fig. 2 shows a simplified block diagram of an exemplary electric drive system in a mining and / or construction machine as shown in Fig. 1 comprising an electrical power unit according to the invention;Fig. 3 shows a block diagram of an embodiment of an electrical power unit according to the invention;Fig. 4 shows a block diagram of an alternative embodiment of an electrical power unit according to the invention;Fig. 5 shows a block diagram of an alternative embodiment of an electric drive system;Figs. 6a-d are block diagrams of an embodiment of an interface unit comprised in an electrical power unit according to the invention; andFig. 7 is a flow chart showing the different steps in the method according to the invention.Description of embodiments

[0024] In the following, a detailed description of a method of controlling the operation of an electrical power unit in a mining and / or construction machine and an electrical power unit comprised in the mining and / or construction machine.113458PC6

[0025] The term “mining and / or construction machine” should in the context of this application be construed broadly and include drilling rigs, particularly rock drilling rigs, but also production, exploration, excavation, and / or construction mining rigs for surface and underground applications.

[0026] When reference is made to a “power source”, it should be understood that reference is made to a source of electrical power, unless explicitly stated otherwise.

[0027] In the drawing figures, like reference numerals designate identical or corresponding elements throughout the several figures. It will be appreciated that these figures are for illustration only and do not in any way restrict the scope of the present disclosure.

[0028] Fig. 1 shows a schematic representation of a mining and / or construction machine in the form of a mining machine or rock drilling rig, generally designated 2. The rock drilling rig 2 comprises a carriage 4 and a rock drill machine 6 attached to the front of the carriage 4. The rock drilling machine 6 is arranged on and connected to the carriage 4 by means of a boom 8, so that the rock drilling machine 6 can be arranged in different positions in relation to the carriage 4 and to the rock to be drilled. Together, the carriage 4, the rock drilling machine 6 and the boom 8 form the main part of the rock drilling rig 2. The carriage 4 is further provided with propulsion means 9, such as wheels or continuous track and propulsion equipment.

[0029] The rock drilling rig 2 further comprises an electric drive system 100, which is connectable to an external grid via a cable interface 12. The rock drilling rig 2 is provided with operative power from either an external energy source, not shown in Fig. 1 , via the cable interface 12, preferably via a cable connected through a breaker, or an internal energy source comprised in the electric drive system 100, such as an electric battery, a super capacitor, or a fuel cell, or a combination thereof. Operative power is power that either powers the propulsion means 9 and / or the rock drilling machine 6. When the rock drilling rig 2 is operated, a control unit of the electric drive system 100 is configured to selectively113458PC7 control operating power from the external energy source or the internal energy source, as will be described below. A work cycle normally comprises a plurality of work tasks. The control unit is further configured to selectively charge the internal energy source with energy from the external electrical source, as will be described below.

[0030] An overall diagram of the electric drive system 100 of an electric mining and / or construction machine in the form of the mining machine of Fig. 1 is shown in Fig. 2. The electric drive system comprises a bus 104 adapted to provide electrical power to an electric drive unit 110 of the mining machine. This bus 104 can be either a DC bus or an AC bus. The term “bus” should in this context be construed broadly and encompass any kind of device adapted to conduct electrical current, irrespective of the number of devices connected thereto.

[0031] The electric drive unit 110 may comprise an electric motor adapted to drive a load device in the form of a compressor, for example. A second electric motor may be provided to drive a load in the form of one or more hydraulic pumps, for example. One or more electric motor drives are provided for controlling the operation of the electric motors provided in the electric drive unit 110. An electric drive unit controller 110a is provided for controlling the operation of the electric drive unit 110.

[0032] This general description of the electric drive system 100 is applicable both for AC application and DC application, and the different parts thereof are designed accordingly. For example, if the external power source in Fig. 2 is an AC network, the motor drives are designed as an AC / DC or AC / AC drive.

[0033] The electric drive system 100 also comprises a power converter 102, the input of which is connectable to an external power source 10, such as a main grid supply or electrical network, via the cable interface 12. The output of the power converter 102 is connected to the bus 104 adapted to provide electrical power to the electric drive unit 110 of the mining machine. The operation of the power converter 102 is controlled by means of a power converter controller 102a, connected thereto.113458PC8

[0034] A power unit 130 is provided for, in addition to the power provided by the power converter 102, powering the electric drive unit 110. The power unit 130 is connected to the bus 104 and via this bus to the electric drive unit 110. The power unit 130 may comprise any kind of electrical power source, such as a battery, a capacitor, a super capacitor etc., or a combination thereof. It is preferred that a battery management system (BMS) 130a is provided for the oversight of the power unit 130, as is conventional. The functions of the BMS 130a may include, but is not limited, to monitoring and protecting the electrical power sources, estimating the operational state and continually optimizing battery performance, and reporting operational status., preferably to the control unit 106.

[0035] The power unit 130 is also connectable to a charging station 20 via a charging port 22.

[0036] Finally, a control unit 106 is provided for controlling the operation of the electric drive system 100. This control unit 106 is preferably connected to the power converter controller 102a, the electric drive unit controller 110a, the BMS 130a. In case the electric drive system 100 is connected to a charger 20, the control unit 106 is preferably connected thereto. By being connected to the different controllers / BMS of the electric drive system 100, the control unit 106 can control the operation thereof. Alternatively, one or more of the power converter controller 102a, the electric drive unit controller 110a, and the BMS 130a can be omitted. If that is the case, the different units of the electric drive system 100 are controlled directly by the controller 106.

[0037] A non-transitory computer-readable source medium is provided, preferably in the control unit 106, that stores a program configured to execute a method controlling the operation of an electrical power unit in a mining machine as described below. Thus, a computer program product comprising instructions which, when the program is executed by a computer, such as the control unit 106, cause the computer to carry out the above-mentioned method of controlling the operation of an electrical power unit in a mining machine.113458PC9

[0038] The power unit 130 will now be described in detail with reference to Fig.3. The power unit 130 comprises a plurality of electrical energy sources, in the embodiment in the figure two electrical energy sources: a first electrical energy source 132 and a second electrical energy source 134. These power sources can be any device that is designed to charge and discharge electrical energy, such as an electric battery, a super capacitor, or a fuel cell. An interface unit 136 is connected to the electrical energy sources 132, 134 and is adapted to connect the electrical energy sources in series or in parallel, depending on external or internal conditions, such as an operating condition of the mining machine 2 in which the power unit 130 is provided. The interface unit 136 is also connectable to a charging station 20, se Fig. 2, via a port 138. It is further connectable to the bus 104 of the electric drive system 100 of an electrical mining and / or construction machine 2, see Fig. 2, via a bus connection 140.

[0039] The nominal voltage of the electrical energy sources 132, 134 can be any voltage suitable for supplying an electrical mining and / or construction machine, but preferred voltages are 800 V and 1500, being standards within the industry. However,.

[0040] In an alternative embodiment of the power unit 130, see Fig. 4, a DC / DC power converter 142 is provided between one of the electric energy sources, in the shown example the first energy source 132, and the interface unit 136. The function of this DC / DC power converter 142 is to regulate the output voltage of the power unit 130, as will be described below with reference to the method. This DC / DC power converter 142 is sized based on the maximum voltage, in the above example 1600 V, and maximum current. This means that this preferably is a full power converter. Optionally, a second DC / DC power converter, not shown in the figures, may be provided between the second energy source 134 and the interface unit 136. With this second DC / DC power converter, it is possible to regulate the output power of the power unit 130 also when the electric energy sources 132, 134 are connected in parallel.113458PC10

[0041] In an alternative embodiment, see Fig. 5, a DC / DC power converter 108 is provided between the electrical power unit 130 and the bus 104. Under the control of the control unit 106, this DC / DC power converter 108 can adjust the voltage provided by the electrical power unit 130 to that of the bus 104.

[0042] An embodiment of an interface unit 136 will now be described with reference to Figs. 6a-d. These figures correspond to Fig. 3 but with the details of the interface unit 136 shown in form of block diagrams. In these block diagrams, electronic switches are shown as boxes interconnected by lines representing electrical connections in the form of electrical conduits. A box without any shading represents an open switch and a box with grey shading represents a closed switch. Positive and negative polarity are marked “Pos” and “Neg”, respectively.

[0043] In Fig. 6a, the switches of the interface unit 136 are shown in positions for charging the first and second electrical power sources 132, 134 in parallel. It is shown how the positive poles Pos1 and Pos2 of the electrical power sources 132, 134 are connected to port 138, which is connectable to the charging station 20, se Fig. 2. The switches leading to port 140, connected to the bus 104, are open, effectively disconnecting the electrical power unit 130 from this bus.

[0044] Correspondingly, in Fig. 6b, the switches of the interface unit 136 are shown in positions for charging the first and second electrical power sources 132, 134 in series. It is shown how the positive pole Pos1 of the first electrical power source 132 is connected to the positive pole of port 138 and the negative pole Neg2 of the second electrical power source 134 is connected to the negative pole of port 138 while the negative pole Neg1 of the first electrical power source 132 and the positive pole Pos2 of the second electrical power source 134 are interconnected. The switches leading to port 140, connected to the bus 104, are open, effectively disconnecting the electrical power unit 130 from this bus.

[0045] In Fig. 6c, the switches of the interface unit 136 are shown in positions for discharging the first and second electrical power sources 132, 134 in parallel. It is shown how the positive poles Pos1 and Pos2 of the electrical power sources 132, 134 are connected to port 140, which is connected to the bus 104, se Fig. 2.113458PC11The switches leading to port 138, connectable to the charging station 20, are open, effectively disconnecting the electrical power unit 130 from the charging station.

[0046] Finally, in Fig. 6d, the switches of the interface unit 136 are shown in positions for discharging the first and second electrical power sources 132, 134 in series. It is shown how the positive pole Pos1 of the first electrical power source 132 is connected to the positive pole of port 140 and the negative pole Neg2 of the second electrical power source 134 is connected to the negative pole of port 140 while the negative pole Neg1 of the first electrical power source 132 and the positive pole Pos2 of the second electrical power source 134 are interconnected. The switches leading to port 138, connectable to the charging station 20, are open, effectively disconnecting the electrical power unit 130 from the charging station.

[0047] A method of controlling the operation of an electrical power unit in an electric mining and / or construction machine according to the invention will now be described in detail, initially with reference to Fig. 7. In this method, the electrical power unit 130 is connectable to a charging station 20, as described above, and comprises at least a first electrical power source 132 and a second electrical power source 134. In this method, in a step 102, you first determine a status of the first and second electrical power sources 132, 134. This status can be any status of the electrical power sources relevant for the function thereof, such as state of charge, state of health, degradation and failure.

[0048] After the status has been determined, in a step 104, the first and second electrical power sources 132, 134 are interconnected depending on any of a number of parameters. These parameters include the status of the first and second electrical power sources 132, 134, a voltage of the charging station 20 or a status of the electric mining or construction machine 2.

[0049] In the case that the mining machine 2 is to be connected to a charging station, the electrical power unit 130 is connected to this charging station 20. The voltage of the charging station 20 is determined, and the first and second electrical113458PC12 power sources 132, 134 are interconnected depending on the voltage of the charging station 20.

[0050] In order to obtain the desired functionality of the electrical power unit 130, the first and second electrical power sources 132, 134 can be connected either in parallel or in series. With the electrical power sources 132, 134 connected in parallel, the electrical power unit 130 provides the voltage of the electrical power unit sources 132 but with the sum of the currents they provide. With the electrical power sources 132, 134 connected in series, the electrical power unit 130 provides the voltage of the sum of the voltages of the electrical power sources 132, 134. For example, with a nominal rating of the electrical power sources 132, 134 of 800 V and 150 A, connecting them in parallel will provide 800 V and two times 150 A, i.e., 300 A, and connecting them in series will provide 1600 V and 150 A.

[0051] In this example, only two electrical power sources 132, 134 are provided. If more than two electrical power sources are provided, some of them may be connected in series and others in parallel.

[0052] It has been described above that the electrical drive system 100 comprises a bus 104. It is preferred that the electrical power unit 130 is connected to this bus 104 and in this case the voltage of the bus 104 is one parameter relevant when interconnecting the electrical power sources 132, 134. For example, with two electrical power sources 132, 134 with a nominal rating of 800 V and a bus 104 operating at 1500 V, the electrical power sources 132, 134 are connected in series, providing a voltage of 1600 V.

[0053] In the embodiment described above with reference to Fig. 4, a DC / DC power converter 142 is provided between the first electrical power source 132 and the bus 104, via the interface unit 136. With this DC / DC power converter 142 provided in the electrical power unit 130, the voltage of the bus 104 or other load, to which the electrical power unit 130 is connected, is first determined. The first and second electrical power sources 132, 134 are connected in series, and the DC / DC power converter 142 is controlled to provide a predetermined voltage to113458PC13 the bus 104 or other load. Thus, with the DC / DC power converter 142, the output voltage of the electrical power unit 130 can be adjusted to match the needs. For example, in the above-described example with two energy power sources 132, 134 with a nominal voltage of 800 V and connected in series, there is a mismatch between the output voltage and the bus voltage. This can be handled by means of controlling the DC / DC power converter 142.

[0054] When the electrical power unit 130 is disconnected from the charging station 20, the first and second electrical power sources 132, 134 are preferably connected in series, but they may also be in parallel, based on the voltage on the bus 104.

[0055] In one embodiment of the method, when the electrical power unit 130 is to be charged, the electrical power sources 132, 134 are disconnected from the bus 104 and are connected to a charging station 20. A state of charge of the electrical power sources 132, 134 is then determined. If the state of charge is above a predetermined threshold, the electrical power sources 132, 134 are connected in series, and if the state of charge is below the predetermined threshold, the electrical power sources 132, 134 are connected in parallel. In this way, when the electrical power sources 132, 134 have a relatively high charge, the charging current is relatively low, and when they are to a large degree discharged, the charging current is relatively high, shortening the charging time.

[0056] Preferred embodiments of a method for controlling the operation of an electrical power unit in an electric mining and / or construction machine as well as such an electrical power unit and an electric mining and / or construction machine with such an electrical power unit have been described. It will be realized that these can be modified within the scope of the appended claims without departing form the inventive idea.

Claims

113458PC14CLAIMS1 . A method of controlling the operation of an electrical power unit (130) in an electric mining and / or construction machine (2), the electrical power unit (130) being connectable to a charging station (20) and comprising at least a first electrical power source (132) and a second electrical power source (134), the method comprising the following steps:- determining a status of the first and second electrical power sources (132, 134), and- interconnecting the first and second electrical power sources (132, 134) depending on any of the following: the status of the first and second electrical power sources (132, 134), a voltage of a charging station (20) or a status of the electric mining or construction machine (2).

2. The method according to claim 1 , comprising the following steps:- connecting the electrical power unit (130) to the charging station (20),- determining the voltage of the charging station (20), and- interconnecting the first and second electrical power sources (132, 134) depending on the voltage of the charging station (20).

3. The method according to claim 1 or 2, wherein the step of interconnecting the first and second electrical power sources (132, 134) comprises connecting the first and second electrical power sources (132, 134) in parallel.

4. The method according to claim 1 or 2, wherein the step of interconnecting the first and second electrical power sources (132, 134) comprises connecting the first and second electrical power sources (132, 134) in series.113458PC155. The method according to any one of claims 1-4, wherein the status of the electrical power sources (132, 134) is any of the following: state of charge, state of health, degradation and failure.

6. The method according to any one of claims 1-5, comprising the additional step of connecting the electrical power unit (130) to a bus (104) of an electric drive system (100) of the electric mining and / or construction machine (2), wherein the status comprises a voltage of the bus (104).

7. The method according to claim 6, comprising the additional step of providing a DC / DC power converter (142) between the first electrical power source (132) and the bus (104).

8. The method according to claim 7, comprising the additional steps of- determining the voltage of the bus (104),- connecting the first and second electrical power sources (132, 134) in series, and- controlling the DC / DC power converter (142) to provide a predetermined voltage to the bus (104).

9. The method according to any one of claims 1-8, wherein, when the electrical power unit (130) is disconnected from the charging station (20), the first and second electrical power sources (132, 134) are connected in series.

10. The method according to any one of claims 6-9, comprising the following steps:- disconnecting the electrical power sources (132, 134) from the bus (104),- connecting the electrical power sources (132, 134) to the charging station (20),- determining a state of charge of the electrical power sources (132, 134),113458PC16- if the state of charge of the electrical power sources (132, 134) is above a predetermined threshold, connecting the electrical power sources (132, 134) in series, and- if the state of charge of the electrical power sources (132, 134) is below the predetermined threshold, connecting the electrical power sources (132, 134) in parallel.11 . The method according to any one of claims 1 -10, comprising the additional step of providing a DC / DC power converter (108) between the electrical power unit (130) and the bus (104).

12. An electrical power unit (130) for an electrical mining and / or construction machine (2), the electrical power unit (130) comprising a first and a second electrical power source (132, 134), the power unit (130) comprising an interface unit (136) connected to the first and second electrical power sources (132, 134) and connectable to a charging station (20) and to a bus (104) of an electric drive system (100) of the electrical mining and / or construction machine (2), wherein the interface unit (136) is adapted to connect the first and second electrical power sources (132, 134) in series or in parallel, depending on an operating condition.

13. The electrical power unit (130) according to claim 11 , comprising a DC / DC power converter (142) between the first electrical power source (132, 134) and the interface unit (136).

14. The electrical power unit according to claim 11 or 12, wherein the electrical power sources (132, 134) are any of the following: an electric battery, a super capacitor, and a fuel cell.

15. An electrically powered mining and / or construction machine (2) comprising113458PC17- a power converter (102), the input of which is connectable to an external power source (10),- an electric drive unit (110),- a bus (104) interconnecting an output of the power converter (102) and an input of the electric drive unit (110),- an electrical power unit (130) according to any of claims 12-14 connected to the bus (104) and connectable to a charging station (20), and- a control unit (106) adapted to control the electrical power unit (130) to perform the method according to any of claims 1-10.

16. A non-transitory computer-readable source medium that stores a program configured to execute the method of any one of claims 1 to 11 in an electrically powered mining and / or construction machine (2) according to claim 15.

17. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of any one of claims 1 to 11 in an electrically powered mining and / or construction machine (2) according to claim 15.

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