Power management for mining machines

Abstract

A method of electrical power management of an electrically powered mining machine (2) is provided, wherein the mining machine comprises an electric drive unit (110), a control unit adapted to control the operation of the electric drive unit (110) wherein the electric drive unit (110) comprises a single electric motor drive (112), a plurality of electric motors (114, 124), each connected to an output of the single electric motor drive (112), and a plurality of load devices (116, 126), adapted to be driven by a respective electric motor of the plurality of electric motors (114, 124). The method comprises the following steps: determining a task schedule of the electrically powered mining machine (2), providing an operating mode for the plurality of electric motors (114, 124) based on the task schedule, and controlling the single electric motor drive (112) based on the operating mode.

Description

POWER MANAGEMENT FOR MINING MACHINESTechnical field

[0001] The present invention relates generally to the field of electrical power management at an electrically powered mining machine, and more specifically to a method of electrical power management in an electronic control system in an electrically powered mining or construction machine and such a mining machine.Background art

[0002] Mining and 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 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 drill rig, where the demands for power and energy are high during rock drilling. This is solved in that the rock drill rig can be connected to an external electrical network when performing its rock drilling work cycle.

[0005] A proposed solution to such problems is the substitution of the combustion engine with an electric motor, driven partly by an energy storage, such as an electric battery and / or a connection to an external electrical network. When the rock drilling rig performs its work cycle with the rock drilling machine, the rock drilling rig must be connected to an external electrical network for powering therock drilling rig. This solution does eliminate direct emissions of CO2 and usage of fossil fuels but does however also provide several drawbacks. One exemplary drawback is the availability of an external electrical network with sufficient power capacity at the work site. Another drawback is the space taken up by the electric motors and associated parts, such as power electronics and control circuits.Summary of invention

[0006] An object of the present invention is to provide a method of electrical power management of an electrically powered mining machine and an electrically powered mining machine, wherein higher system compactness and increased control functionalities are achieved.

[0007] According to a first aspect of the invention, there is provided a method of electrical power management of an electrically powered mining machine, the mining machine comprising an electric drive unit, a control unit adapted to control the operation of the electric drive unit, wherein the electric drive unit comprises a single electric motor drive, a plurality of electric motors, preferably two electric motors, each connected to an output of the single electric motor drive, and a plurality of load devices, preferably two or more load devices, adapted to be driven by a respective electric motor of the plurality of electric motors, the method comprising the following steps: determining a task schedule of the electrically powered mining machine, providing an operating mode for the plurality of electric motors based on the task schedule, and controlling the single electric motor drive based on the operating mode.In a preferred embodiment, the step of controlling the single electric motor drive comprises limiting a total power to the plurality of motors which is lower than the sum of power ratings of the plurality of electric motors.

[0008] In a preferred embodiment, the operating mode is determined based on an operator command, a predetermined task schedule, a state of the external power source, a state of an internal power source, or a fault state.

[0009] In a preferred embodiment, the operating mode is drilling, idling, rod handling, or tramming.

[0010] In a preferred embodiment, the step of controlling the single electric motor drive comprises operating the plurality of electric motors in a predetermined cycle of operations or task modes.

[0011] In a preferred embodiment, the step of controlling the single electric motor drive comprises sensing a power requirement of outputs of the single electric motor drive and adjusting the operation mode in dependence on the sensed power requirement.

[0012] In a preferred embodiment, the controlling of the single electric motor drive is additionally based on power requirements from the plurality of load devices.

[0013] In a preferred embodiment, the controlling of the single electric motor drive is additionally based on predicted cooling requirements.

[0014] In a preferred embodiment, the electrically powered mining machine comprises an internal power source, preferably an electric battery, a super capacitor, or a fuel cell, or a combination thereof, connected to the electric drive unit, wherein the controlling of the single electric motor drive is additionally based on a State of Charge or other operational state of the internal power source.

[0015] In a preferred embodiment, the electric drive unit comprises a plurality of motor drive converters, preferably DC / AC converters, between the single electric motor drive and a respective of the plurality of electric motors, and wherein the method comprises operating the plurality of motor drive converters with a fixed voltage gain.

[0016] In a preferred embodiment, a power converter is provided, the input of which is connectable to an external power source and the output of which is connected to the bus, and wherein the step of controlling the single electric motor drive additionally comprises controlling the power converter.

[0017] According to a second aspect of the invention, a power converter is provided, the input of which is connectable to an external power source, a control unit adapted to control the operation of the power converter, an electric drive unit, and a bus interconnecting an output of the first power converter and an input of the electric drive unit, wherein the electric drive unit comprises a single electric motor drive, a plurality of electric motors, preferably two electric motors, each connected to an output of the single electric motor drive, and a plurality of load devices, preferably two load devices, adapted to be driven by a respective electric motor of the plurality of electric motors, and wherein the control unit is adapted to perform the method according to the invention.

[0018] In a preferred embodiment, the power rating of the single electric motor drive is lower than the sum of the power ratings of the plurality of electric motors.

[0019] In a preferred embodiment, the plurality of load devices comprises at least a compressor and / or at least a hydraulic system.

[0020] In a preferred embodiment, the electric drive unit comprises a plurality of motor drive converters, preferably DC / AC converters, between the single electric motor drive and a respective of the plurality of electric motors.

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

[0022] According to a fourth 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 invention in an electrically powered mining 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 construction machine in the form of a surface drilling rig that is electrified and has the possibility of connecting to an electrical grid;Fig. 2 shows a simplified block diagram of an exemplary electric drive system in a mining machine as shown in Fig. 1 ;Fig. 3 shows a simplified block diagram of an alternative exemplary electric drive system in a mining machine as shown in Fig. 1 ;Fig. 4 shows a simplified block diagram of another alternative exemplary electric drive system in a mining machine as shown in Fig. 1 ;Figs. 5-7 show alternative embodiments of an electric motor unit comprised in a mining machine according to the invention; andFig. 8 shows a time diagram showing operation in different modes and with power curtailment requests.Description of embodiments

[0024] In the following, a detailed description of a method of electrical power management of an electrically powered mining or construction machine and a mining machine with a control system arranged to perform the method according to the present invention is presented.

[0025] The term “mining 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 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 thatthese 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 machine in the form of a 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, preferably comprising a circuit breaker. 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, 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 selectively 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 the mining machine of Fig. 1 is shown in Fig. 2. The electric drive system comprises a bus 104 adapted to provide electric 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 deviceadapted to conduct electrical current, irrespective of the number of devices connected thereto.

[0031] In the present example, the electric drive unit 110 comprises a first electric motor 114 adapted to drive a load device in the form of a compressor 116. For controlling the operation of the first electric motor 114, a single electric motor drive 112 is provided between the bus 104 and the first electric motor 114. A second electric motor 124 is provided to drive a load in the form of one or more hydraulic pumps 126. For controlling the operation of the second electric motor 124, the single motor drive 112, which is provided for driving the first electric motor 114, is also provided between the bus 104 and the second electric motor 124 for driving also the second electric motor 124. In other words, a single motor drive 112 is provided to drive two or more electric motors.

[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 single motor drive 112 is designed as an AC / DC or AC / AC drive.

[0033] Finally, a control unit 106 is provided for controlling the operation of the single motor drive 112. To this end, this control unit 106 is connected to the single motor drive 112 and preferably also to the load devices 116, 126 for sensing the load requirements thereof. A non-transitory computer-readable storage medium is provided that stores a program configured to execute a method of electrical power distribution 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 electrical power distribution in a mining machine.

[0034] In an alternative embodiment, shown in Fig. 3, the electric drive system also comprises a power converter 102, the input of which is connectable to an external power source 10, such as a main grid supply, via the cable interface 12. The output of the power converter 102 is connected to the bus 104 adapted to provide electric power to the single electric drive unit 110 of the mining machine.The operation of the power converter 102 is controlled by means of the control unit 106, connected thereto. Alternatively, a separate control unit (not shown) is provided for controlling the operation of the power converter 102. If this is the case, the two control units are preferably interconnected for exchanging data and instructions.

[0035] In an alternative embodiment, shown in Fig. 4, an internal power source 130 is provided for powering the electric drive unit 110. The internal power source 130 is connected to the bus 104 and via this bus to the electric drive unit 110. The internal power source can be any kind of electric power storage, such as a battery, a capacitor, a super capacitor etc., or a combination thereof. It is preferred that a battery management system (BMS) 132 is provided for the oversight of the internal power source 130. This BMS 132 is preferably connected to the control unit 106 for exchange of information and instructions. The functions of the BMS 132 may include, but is not limited, to monitoring and protecting the internal power source, estimating the operational state and continually optimizing battery performance, and reporting operational status, preferably to the control unit 106.

[0036] The electric drive unit 110 can take several different configurations, as will be explained below with reference to Figs. 5-7. In Fig. 5, the electric motor drive 112 is a single AC drive with a plurality of outputs, in the shown example two outputs, each output with three phases. The input of the single motor drive 112 can be either DC power or AC power, depending on the configuration of the electric drive system 100 and the external power source 10. The single motor drive 112 may in this embodiment comprise a 9-switch converter or a multiphase DC / AC converter. The power requirements from the load devices 116, 126, such as pump and compressor, are used to control the power distribution from the single electric motor drive 112. The power requirements during a work cycle may vary between 0 to 100 % of the motor rating while the motor rating (tens of kW to MW) depends on the size of the rig.

[0037] In Fig. 6, an embodiment of the electric drive unit 110 is shown wherein both the electric motors 114, 124 are fed from an optimized single DC drive, suchas a multi-port DC / DC converter. In other words, the power distribution among the electric motors 114, 124 is done through a single DC drive with two DC outputs.

[0038] In an alternative embodiment, see Fig. 7, the electric motors 114, 124 are AC motors, wherein a second stage of DC / AC conversions are provided in the form of DC / AC converters 118, 128, connected between the outputs of the single motor drive 112 and the inputs of a respective of the electric motors 114, 124.

[0039] The power requirements from the pump and compressor are used to control the power distribution from the single motor drive 112.

[0040] It will be appreciated that the different embodiments of an electric drive unit 110 described above with reference to Figs. 5-7 can be combined with the different designs of the electric drive systems 100 described above with reference to Fig. 2-4. The exact configuration depends on whether the external power source 10 is an AC or DC source, the electric motors 114, 124 are AC or DC motors etc.

[0041] A method of electrical power management of an electrically powered mining machine will now be described in detail. In this method, a single electric drive unit is used for controlling and powering two or more electric motors in an electric drive system as described above.

[0042] The method of electrical power distribution between the plurality of electric motors 114, 124 initially involves determining a task schedule of the electrically powered mining machine 2. Based on the task schedule, an operating mode for the plurality of electric motors 114, 124 is provided based on the task schedule. This operating mode can be for example drilling, idling, rod handling, or tramming. Based on the current operating mode, the single electric motor drive 112 is controlled based on the operating mode.

[0043] This distribution of electrical power can be implemented in different ways. In one embodiment, when controlling the single electric motor drive 112, the total power provided to the plurality of motors 114, 124 is limited to a power which is lower than the sum of power ratings of the plurality of electric motors 114, 124.

[0044] The determination of operating mode can also be based on other parameters, such as an operator command, a predetermined task schedule, a state of the external power source 10, a state of an internal power source 130, as described below, or a fault state.

[0045] It is preferred that the single electric motor drive 112 is controlled to operate the electric motors 114, 124 in a predetermined cycle of operations or task modes. In Fig. 8, it is illustrated how the electric motors are operated in a first task mode during a first time interval 1 , in a second task mode during a second time interval 2, in a third task mode during a third time interval 3, and in a first task mode during a fourth time interval 4. In Fig. 8, there is also illustrated a power curtailment request associated with the operation.

[0046] When controlling the single electric motor drive 112, the power requirements of the outputs of the single electric motor drive 112 are preferably sensed. In other words, the total power requirement is sensed. The operation mode is then adjusted in dependence on the sensed power requirement.

[0047] Optionally, the single electric motor drive 112 is additionally controlled based on power requirements from the plurality of load devices 116, 126. This involves individual load measurements from the loads devices 116, 126.

[0048] One aspect of electrical power management of an electrically powered mining machine is the cooling requirements. It is therefore preferred that the single electric motor drive 112 is additionally controlled based on predicted cooling requirements.

[0049] When the electrically powered mining machine 2 comprises an internal power source 130, such as an electric battery, a super capacitor, or a fuel cell, or a combination thereof, connected to the bus (104), as in the embodiment described above with reference to Fig. 4, the controlling of the single electric motor drive 112 is preferably also based on a State of Charge (SoC) of the internal power source 130. To obtain this information, the control unit 106 is preferably connected to the battery management system 132, through which the SoC and other informationabout the internal power source 130 can be obtained. In its simplest form, the BMS can be power electronics of a battery to connect it to the bus 104.

[0050] When the electric drive unit 110 comprises a plurality of motor drive converters 118, 128, such as DC / AC converters, between the single electric motor drive 112 and a respective of the plurality of electric motors 114, 124, and the plurality of motor drive converters 118, 128 are preferably operated with a fixed voltage gain.

[0051] When a power converter 102 is provided between an external power source 10 and the bus 104, the control of the single electric motor drive 112 preferably additionally involves controlling this power converter 102.

[0052] Although the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and the invention is not limited to the disclosed embodiments. For example, a single motor drive has been shown driving two electric motors. It will be appreciated that the inventive idea is applicable also to electric drive systems with the single motor drive driving three or more electric motors. One of the load devices has been described as a compressor and the other as hydraulic pump, but it will be appreciated that the load devices are not limited to these devices.

Claims

CLAIMS1 . A method of electrical power management of an electrically powered mining machine (2), the mining machine comprising an electric drive unit (110), a control unit adapted to control the operation of the electric drive unit (110) wherein the electric drive unit (110) comprises a single electric motor drive (112), a plurality of electric motors (114, 124), preferably two electric motors, each connected to an output of the single electric motor drive (112), and a plurality of load devices (116, 126), preferably two load devices, adapted to be driven by a respective electric motor of the plurality of electric motors (114, 124), the method comprising the following steps:- determining a task schedule of the electrically powered mining machine (2),- providing an operating mode for the plurality of electric motors (114, 124) based on the task schedule, and- controlling the single electric motor drive (112) based on the operating mode.

2. The method according to claim 1 , wherein the step of controlling the single electric motor drive (112) comprises limiting a total power to the plurality of motors (114, 124) which is lower than the sum of power ratings of the plurality of electric motors (114, 124).

3. The method according to claim 1 or 2, wherein the operating mode is determined based on an operator command, a predetermined task schedule, a state of the external power source (10), a state of an internal power source (130), or a fault state.

4. The method according to any one of claims 1-3, wherein the operating mode is drilling, idling, rod handling, or tramming.

5. The method according to any one of claims 1-4, wherein the step of controlling the single electric motor drive (112) comprises operating the plurality of electric motors (114, 124) in a predetermined cycle of operations or task modes.

6. The method according to any one of claims 1-5, wherein the step of controlling the single electric motor drive (112) comprises sensing a power requirement of outputs of the single electric motor drive (112) and adjusting the operation mode in dependence on the sensed power requirement.

7. The method according to any one of claims 1-6, wherein the controlling of the single electric motor drive (112) is additionally based on power requirements from the plurality of load devices (116, 126).

8. The method according to any one of claims 1-7, wherein the controlling of the single electric motor drive (112) is additionally based on predicted cooling requirements.

9. The method according any one of claims 1-8, wherein the electrically powered mining machine (2) comprises an internal power source (130), preferably an electric battery, a super capacitor, or a fuel cell, or a combination thereof, connected to the electric drive unit (110), wherein the controlling of the single electric motor drive (112) is additionally based on a State of Charge or other operational state of the internal power source (130).

10. The method according to any one of claims 1 -9, wherein the electric drive unit (110) comprises a plurality of motor drive converters (118, 128), preferably DC / AC converters, between the single electric motor drive (112) and a respective of the plurality of electric motors (114, 124), and wherein the method comprises operating the plurality of motor drive converters (118, 128) with a fixed voltage gain.11 . The method according to any one of claims 1 -10, wherein a power converter (102) is provided, the input of which is connectable to an external power source (10) and the output of which is connected to the bus (104), and wherein thestep of controlling the single electric motor drive (112) additionally comprises controlling the power converter (102).

12. An electrically powered mining machine comprising a power converter (102), the input of which is connectable to an external power source (10), a control unit (106) adapted to control the operation of the power converter (102), an electric drive unit (110), and a bus (104) interconnecting an output of the first power converter (102) and an input of the electric drive unit (110), wherein the electric drive unit (110) comprises a single electric motor drive (112), a plurality of electric motors (114, 124), preferably two electric motors, each connected to an output of the single electric motor drive (112), and a plurality of load devices (116, 126), preferably two load devices, adapted to be driven by a respective electric motor of the plurality of electric motors (114, 124), and wherein the control unit (106) is adapted to perform the method of any of claims 1- 11.

13. The electrically powered mining machine according to claim 12, wherein the power rating of the single electric motor drive (112) is lower than the sum of the power ratings of the plurality of electric motors (114, 124).

14. The electrically powered mining machine according to claim 12 or 13, wherein the plurality of load devices (116, 126) comprises at least a compressor (116) and / or at least a hydraulic system (126).

15. The electrically powered mining machine according to any one of claims 11-13, wherein the electric drive unit (110) comprises a plurality of motor drive converters (118, 128), preferably DC / AC converters, between the single electric motor drive (112) and a respective of the plurality of electric motors (114, 124).

16. A non-transitory computer-readable storage medium that stores a program configured to execute the method of any one of claims 1 to 11 in an electrically powered mining machine according to claim 12.

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 machine according to claim 12.

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