Battery system and method for electric power flow control therein

Abstract

The present disclosure relates to a battery system for powering at least one electric traction motor of a mining vehicle, the battery system comprising a first battery portion, a second battery portion; each battery portion comprising one or more battery cells, one or more thermal management system (TMS), one or more main electric box (MEB) and one or more high power DC-DC module; wherein said first battery portion and said second battery portion are adapted for simultaneous providing of an electric power flow to said at least one electric traction motor; and wherein said electric power flow to and / or from the first battery portion and / or the second battery portion being controlled by at least one high power DC-DC module. The disclosure also relates to a vehicle comprising said battery system and a method for controlling electric power flow in a battery system.

Description

METHOD AND APPARATUS FOR ELECTRIC POWER FLOW CONTROL IN A BATTERY SYSTEM Technical field

[0001] The present disclosure relates generally to battery powered electric vehicles and in particular to a method and an apparatus for electric power flow control in a battery powered electric mining vehicle. Background

[0002] There exist various types of vehicle propulsion systems comprising electric machines. For example, a vehicle can be operated by means of an electric machine solely, or by means of an arrangement comprising both an electric machine and an internal combustion engine. The latter alternative is often referred to as a hybrid vehicle (HEV). According to known technology, electric machines are operated by means of a storage system for electric energy arranged in the vehicle, typically in the form of a battery unit which is formed by a plurality of rechargeable battery cells and an associated control unit.

[0003] For a driver of an electrically operated vehicle, it is necessary to obtain information related to the capacity of a battery. Such information can be useful for example for determining the remaining distance which can be travelled with the vehicle until the battery is discharged to such a low level that the vehicle cannot be operated.

[0004] In order to estimate the capacity of a traction battery for a vehicle, it is useful to determine the so-called state of charge (SOC) of the battery. The SOC parameter is normally expressed in percent and corresponds to the present battery energy capacity as a percentage of its nominal capacity. The SOC can be determined by integrating the battery current over time, based on a start SOC as well as the battery capacity, which varies over time. The battery capacity can be determined by integrating the current over time and linking it to the SOC at start and finish of the integration process.110602pc 2

[0005] One problem with current battery powered electric vehicles is the stationary charging time of the battery system; the larger the battery capacity the longer it normally takes to charge the battery with a standard charger. Another problem with battery powered electric vehicles is that the battery systems often lack an efficient power flow control to control where electric power / energy is pushed and pulled from during different modes of electric vehicle operation such as stationary charging, motoring and re-generation. Summary

[0006] It is therefore an object of the embodiments herein to provide an approach for reducing the stationary charging time and at the same time improving an electric power flow control in stationary charging mode, motoring mode and / or regeneration mode in a battery powered electric vehicle to better control at least one of SOC and charging rate of the battery system.

[0007] In a first aspect of the present disclosure, it is provided a battery system according to claim 1, i.e., a battery system for powering at least one electric traction motor of a mining vehicle. The battery system comprises a first battery portion and a second battery portion; each battery portion comprising one or more battery cells, one or more thermal management system (TMS), one or more main electric box (MEB) and one or more high power DC-DC module; wherein said first battery portion and said second battery portion are adapted for simultaneous providing of an electric power flow to said at least one electric traction motor; and wherein said electric power flow to and / or from the first battery portion and / or the second battery portion being controlled by at least one high power DC-DC module.

[0008] This provides the advantage that the battery system may be connected to two battery chargers at once. This may double the rate at which the battery may be charged.

[0009] Another advantage is that the battery system may have a reduced arc flash probability and / or severity.110602pc 3

[0010] In various example embodiments of the present disclosure said first battery portion comprises a first TMS and a first MEB and said second battery portion comprises a second TMS and a second MEB.

[0011] The advantage of these example embodiments is that the thermal management systems may be adapted and optimized for different types of battery portions.

[0012] In various example embodiments of the present disclosure a first battery portion is connectable to a first battery charger and a second battery portion is connectable to a second battery charger.

[0013] The advantage of these example embodiments is that stationary charging time may be reduced as two chargers may be charging the two battery portions at the same time. Another advantage of these embodiments is that a first battery charges may be adapted for charging the first battery portion and a second battery charger nay be adapted for charging the second battery portion, where said first and second battery portions may have different battery chemistry for instance.

[0014] In another aspect of the present disclosure, it is provided an electric mining vehicle comprising a battery system according to the first aspect of the disclosure. The electric mining vehicle comprises at least one electric traction motor configured to drive at least one wheel on a front axle or a rear axle of the electric mining vehicle; a battery system comprising a first battery portion, a second battery portion; each battery portion comprising one or more battery cells, one or more thermal management system (TMS), one or more main electric box (MEB) and one or more high power DC-DC module; wherein said first battery portion and said second battery portion are adapted for simultaneous providing of an electric power flow to said at least one electric traction motor; and wherein said electric power flow to and / or from the first battery portion and / or the second battery portion being controlled by at least one high power DC-DC module.110602pc 4 In yet another aspect of the present disclosure it is provided a method for controlling electric power flow according to claim 7. The method is applicable in a battery system for powering at least one electric traction motor of a mining vehicle, the battery system comprising a first battery portion, a second battery portion; each battery portion comprising one or more battery cells, one or more thermal management system (TMS), one or more main electric box (MEB) and one or more high power DC-DC module; wherein said first battery portion and said second battery portion are adapted for simultaneous providing of an electric power flow to said at least one electric traction motor. Said method comprises the step of: controlling said electric power flow to and / or from at least one battery portion with at least one high power DC-DC module provided in the electric power flow between said first and second battery portions or from at least one battery portion and said electric traction motor and thereby controlling at least one of State Of Charge (SOC) and / or charge rate of said first and / or said second battery portion.

[0015] Brief description of drawings

[0016] The various aspects of the non-limiting embodiments, including particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which:

[0017] Fig.1-6 depicts various example embodiments of a battery system with high power flow control according to the present disclosure. Detailed description

[0018] Non-limiting embodiments of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Like reference characters refer to like elements throughout.

[0019] In the following, according to embodiments herein which relate to controlling an electric power flow between at least one battery portion and an110602pc 5 electric machine or between a first battery portion and a second battery portion, there will be disclosed an approach according to which improved electric power control set-ups are provided.

[0020] Figure 1 depicts a first example embodiment according to the present disclosure of a battery system 100 with high power electric flow control to an electric machine 200. The battery system 100 comprises a first battery portion 110 and a second battery portion 120. The first battery portion 110 comprises a plurality of battery packs 112. In this example embodiment the number of said battery packs 1122 are 4, however 1, 2, 3, 5 or more battery packs are possible. The first battery portion 110 further comprises a thermal management system (TMS) 114 for controlling the temperature of the first battery portion 110 and a main electric box (MEB) 116 for connecting the first battery portion 110 to one or a plurality of loads.

[0021] The second battery portion 120 comprises a plurality of battery packs 122. In this example embodiment the number of said battery packs are 4, however 1, 2, 3, 5 or more battery packs are possible. The second battery portion 120 further comprises a thermal management system (TMS) 124 for controlling the temperature of the second battery portion 120 and a main electric box (MEB) 126 for connecting the second battery portion 120 to one or a plurality of loads.

[0022] Battery packs 112 in the first battery portion 110 may have a different chemistry, voltage, state of health, etc. compared to battery packs 122 in the second battery portion 120. A battery pack may in various example embodiments be super capacitor packs. In various example embodiments a first battery portion 110 and / or second battery portion 120 may comprise only one battery pack. In various example embodiments a first battery portion 110 and / or a second battery portion 120 may comprise a mix of battery packs and super capacitor packs. In various example embodiments a first battery portion 110 and / or second battery portion 120 may only comprise super capacitor packs. Each battery pack 112, 122 may comprise one or a plurality of battery cells.110602pc 6

[0023] The first battery portion 110 may be charged with a first CCS charger and the second battery portion 120 may be charged with a second CCS charger. An advantage of having the battery system 100 divided into two battery portions 110, 120 is that it reduces arc flash probability and / or severity, i.e., arcing through air between HV+ and HV-. Another advantage of having the battery system 100 divided into two battery portions 110, 120 is faster charging rates. The battery portions may be connected to their own battery chargers simultaneously. Simultaneous charging by two battery chargers 310, 320 may double the rate at which the battery system 100 may be charged. This in turn may allow for battery charge time to be comparable to that of smaller batteries. The battery portions 110, 120 may be physically contained in one enclosure or kept as two smaller separate enclosures. In the example embodiment sin figure 1 both battery portions 110, 120 connect to one and the same electric machine and act as one single large battery system 100. The electric machine will recognize said first and second battery portions 110, 120 as a single battery system 100.

[0024] In figure 1 the battery system 100 is connected to an electric machine 200. The electric machine in figure 1 comprises a high-power DC-DC module 130, a vehicle electric power distribution box 210, traction motors 220, auxiliary motors 230 and additional machine loads 240. The high-power DC-DC module 130 controls the power flow to and from the battery system 100. The vehicle electric power distribution box 210 distributes the electric power to machine loads such as traction motors 220, Auxiliary motors 230 and additional machine loads 140. The tractions motors 220 may be electric motors for propelling the machine in forwards and / or backwards direction. The auxiliary motors 230 may be servo motors for power steering and / or power brakes etc. Additional machine loads may be lamps, fans or seat / steering wheel heating etc.

[0025] In figure 1 the first battery portion 110 is connected to said vehicle electric power distribution box 210 via the high-power DC-DC module 130. Bidirectional electric power flow goes between said high-power DC-DC module 130 and MEB denoted by 140. Bidirectional electric power flow also goes between said high power DC-DC module 130 and said vehicle electric power distribution110602pc 7 box 210 denoted by 150. The second battery portion 120 is directly connected to said vehicle electric power distribution box 210. The advantage of the setup illustrated in figure 1 is the stability of the machines HV DC. The battery portion that is connected directly to the machine, i.e., battery portion 120, can react instantaneously to electric power draw, and re-generation. The battery portion that is connected through the high-power DC-DC module, i.e., battery portion 110, therefore can react slower without issue. This setup is more forgiving to sudden current spikes from traction and auxiliary inverters. Although current spikes can likely be tuned out of most inverters, it may require firmware changes and tuning. In figure 1 the machine 200 is provided with a combined HV DC bus. In figure 1 the DC bus voltage to the machine 200 is floating and refenced to the battery portion that is directly connected to the machine DC bus, i.e., the second battery portion 120. Electric power flow is only directly controlled to the first battery portion 110, which is connected through the high-power DC-DC module 130. The high- power DC-DC module 130 may be configured to effectively take half of the machine load and send it though the high-power DC-DC module 130. This effectively controls electric power to each of the battery portions 110, 120.

[0026] A battery system 100 comprising a first battery portion 110 and a second battery portion 120 may have the ability to physically separate said battery portions 110, 120 and will be easier to crane in and out of the vehicle. The first battery portion 110 may be combined with a second battery portion 120, where said first and second battery portions may have different chemistry, batteries / supercaps and / or different state of health. The battery packs 112, 122 may comprise one or several battery cells.

[0027] In various example embodiments the high-power DC-DC module 130 may have a battery system electric power flow 140 with a voltage varying from 0- 950V DC and with a maximum current of 960A. The 960A may be split into a plurality of channels within said high power DC-DC module 130, for instance the number of channels may vary between 1-16 channels. Said high power DC-DC module may be provided with an internal control unit. The internal control unit in the high-power DC-DC module may be set to an output current and voltage110602pc 8 setpoint for controlling electric power flow bidirectionally. Communication with said internal control unit may be through CAN-bus, automotive ethernet, WiFi, Blue tooth, 3G, 4G and / or 5G telecommunication network etc. The High-power DC-DC module 130 may be a BrightLoop DCHV LP, a BrightLoop DCHV MP, an Aradex VP5000-FCDC500, a Foripower FRF 140 or 150 etc. The voltage and current set points in the high-power DC-DC module may be varied on the fly to control how much electric power / current flows through the high-power DC-DC module at a specified voltage. One may design the control unit for sending these current and voltage setpoints to the high-power DC-DC module 130 on the fly during machine operation, e.g., propulsion of the electric mining machine. The control unit may examine and take into account the following factors: Battery state such as state of charge (SOC), state of health (SOH), battery temperature, max charging rates, max discharging rates and machine load and machine state. The electric high- power DC-DC unit is essentially controlling where the electric power flows in the machine and batteries. For instance, when the machine is motoring, from which battery portion 110, 120 does the electric power come from: 50 / 50, 25 / 75, 10 / 90, etc. When the machine is regenerating, from which battery portion does the electric power flow back to: 50 / 50, 25 / 75, 10 / 90, etc.

[0028] In stationary charging mode the vehicle is at rest and one or both battery chargers 310, 320 is charging the battery system 100. When stationary charging and both CCS ports are connected, one also may need to flow electric power from one battery portion to another battery portion depending on their charging level. The high-power DC-DC module 130 may control the electric power flow in stationary charging mode between said first and second battery portions. When stationary charging and only one CCS ports is connected, electric power flow need being transferred to the other battery to ensure they both have equal SOC. Electric power flow is just as much about controlling bus voltage as it is where the electric power comes from, what SOC the battery portion is at, and fast / slow each battery portion is charged and discharged.

[0029] In motoring mode the battery system 100 provides electric power via the high power DC-DC module 130 to the electric machine 200. In the motoring mode110602pc 9 the machine may be provided with battery power from the first battery portion 110 and the second battery portion 120 in various relations such as 50 / 50, 25 / 75, 10 / 90. Electric power flow from the different battery portions is regulated by the high-power DC-DC module 130.

[0030] In regeneration mode the electric machine 200 provides electric power to the battery system 100 via the high-power DC-DC module 130. In this mode the generator acts as an electric power source and provides electric power flow in backwards direction towards the battery system 100 for charging the same. The high-power DC-DC module 130 in between the electric machine 200 and the battery system 100 will control the electric power flow to the battery system 100.

[0031] In various example embodiments of the present disclosure said first and second battery portions 110, 120 are also adapted for providing electric power flow to at least one auxiliary machine load such as electrohydraulic motors, electric water pumps, electric heating devices, fan equipment etc. The advantage of these embodiments is that the battery system is capable of handling various types of electric loads.

[0032] In various example embodiments of the present disclosure battery packs 112, 122 in a single battery portion 110, 120 may be identical or different to each other. A first battery portion 110 may for instance be built up from 8 battery packs 112 whereas a second battery portion 120 may be built up by 15 battery packs 122. Battery packs 112, 122 may be standard Northvolt battery packs such as B4ST or B5MT.The advantage of these example embodiments is that different battery portions 110, 120 may be built up by various types of battery packs 112, 122.

[0033] Figure 2 depicts a second example embodiment according to the present disclosure of a battery system 100 with high electric power flow control to the electric machine 200. The difference compared to the embodiment illustrated in figure 1 is the location of the high-power DC-DC module 130. Here the high-power DC-DC module is located inside the battery system 100 whereas in figure 1 the high-power DC-DC module is located inside the machine 200. In various example110602pc 10 embodiments said electric power flow to and from said battery system may be controlled remotely from said high power DC-DC module by setting an upper and / or lower limit to current and voltage.

[0034] Figure 3 depicts a third example embodiment according to the present disclosure of a battery system 100 with high electric power flow control to the electric machine 200. The difference compared to the embodiment illustrated in figure 1 is that electric power flow from both the first battery portion 110 and the second battery portion 120 goes via the high-power DC-DC module 130 to the vehicle electric power distribution box 210. Here there is a bidirectional electric power flow 140 between said MEB 116 in said first battery portion 110 and said high power DC-DC module 130 as well as a bidirectional electric power flow 142 between said MEB 126 in said second battery portion 120 and said high power DC-DC module 130. The primary benefit of the setup in figure 3 is that the electric machine 200 can be held at a constant higher voltage than the battery system 100. This leads to a better torque and power performance from the motors. This derives from the fact that the inverters do not have to flux weaken the interior permanent magnet motors as early as in the embodiments illustrated in figure 1 and 2. Another benefit with the setup illustrated in figure 3 is that it significantly reduces arc flash probability and severity to the electric machine 200. Since the high-power DC-DC module 130 controls current, any short circuit / arc flash will be significantly reduced in magnitude, if not eliminated. Figure 4 depicts a fourth example embodiment according to the present disclosure of a battery system 100 with high electric power flow control to the electric machine 200. The difference compared to the embodiment illustrated in figure 3 is the location of the high-power DC-DC module 130. Here the high-power DC-DC module is located inside the battery system 100 whereas in figure 3 the high- power DC-DC module is located inside the electric machine 200. In figure 3 and 4 The machine has 1 combined HV DC bus. The machine DC bus is held constant, e.g., 800VDC. Electric power flow may be directly controlled through each battery portion 110, 120.110602pc 11

[0035] Figure 5 depicts a fifth example embodiment according to the present disclosure of a battery system with high power electric flow control. In figure 5 The machine has separate DC buses 160, 162 for each of the battery portions 110, 120. Each of the DC bus voltages are floating and referenced to the respective battery portions 110, 120 connected to it. The high-power DC-DC module 130 may act to flow electric power between each of the battery portions 110, 120 to control SOC. In figure 5 the high-power DC-DC module 130 is connected between the first battery portion 110 to the second battery portion 120 via a first MEB 116 to a second MEB 126 respectively. A bidirectional high electric power flow 140 between said first MEB 116 and said high power DC-DC module 130 is denoted with 140 and a bidirectional high electric power flow 142 between said second MEB 126 and said high power DC-DC module 130 is denoted with 142. Said first MEB 116 is directly connected to a first vehicle electric power distribution box 210 and the electric power flow in between said units is denoted with 162. Said second MEB 126 may be directly connected to a second vehicle electric power distribution box 211 and the electric power flow in between said units is denoted with 160. The first vehicle electric power distribution box 210 may be distributing the electric power to various machine loads such as additional machine loads 240, traction motor 220a. The second vehicle electric power distribution box 211 may be distributing the electric power to various machine loads such as auxiliary motors 230, traction motor 220b. Traction motor 220a may for instance be the front wheels of a battery powered electric mining machine. Traction motor 220b may for instance be the rear wheels of a battery powered electric mining machine. Auxiliary motors may be electric hydraulic motors, electric servo assisted motors, etc. Additional machine loads may be electric fan, electric seat heating, electric compartment heating etc.

[0036] Figure 6 depicts a fifth example embodiment according to the present disclosure of a battery system with high electric power flow control. The difference as compared to figure 5 is how the electric power flow is distributed from the first and second vehicle electric power distribution box. In figure 5 the traction motor 220a is solely receiving its electric power from the first battery portion 110 and traction motor 220b solely receiving its electric power from the second battery110602pc 12 portion 120, i.e., the front wheels are provided with electric power from a first battery portion and the rear wheels are provided with electric power from the second battery portion whereas in figure 6 traction motor 220a is receiving electric power from both said first and second battery portions 110, 120 and traction motor 220b is also receiving electric power from said first and second battery portion 110, 120, i.e., in figure 6 one front wheel may be provided with electric power from a first battery portion and a second front wheel may be provide with electric power from a second battery portion. The same applies to the rear wheels where one wheel my receive electric power from a first battery portion and a second wheel may receive electric power from a second battery portion.

[0037] In various example embodiments the battery packs 112, 122 may have a nominal voltage which may be higher or lower than the voltage provided to the machine 200. The high voltage DC-DC module 130 is configured to regulate the voltage up and / or down depending on the configuration of the battery portions and the desired electric power flow by the electric machine 200. The high-power DC- DC module 130 is configured to reduce input and output current and voltage ripple. The high-power DC-DC module 130 is configured to connect a plurality of battery portions with different voltage levels to a common high voltage DC bus with a predetermined voltage level.

[0038] The person skilled in the art realizes that the present disclosure by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. It should furthermore be noted that the drawings not necessarily are to scale, and dimensions of certain features may have been exaggerated for the sake of clarity. Emphasis is instead placed upon illustrating the principle of the embodiments herein. Additionally, in the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality.

[0039] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

110602pc 13 CLAIMS 1. A battery system for powering at least one electric traction motor of a mining vehicle, the battery system comprising a first battery portion, a second battery portion; each battery portion comprising one or more battery cells, one or more thermal management system (TMS), one or more main electric box (MEB) and one or more high power DC-DC module; wherein said first battery portion and said second battery portion are adapted for simultaneous providing of an electric power flow to said at least one electric traction motor; and wherein said electric power flow to and / or from the first battery portion and / or the second battery portion being controlled by at least one high power DC-DC module.

2. The battery system according to claim 1, wherein said first battery portion comprising a first TMS and a first MEB and said second battery portion comprising a second TMS and a second MEB.

3. The battery system according to claim 1 or 2, wherein a first battery portion is connectable to a first battery charger and a second battery portion is connectable to a second battery charger.

4. An electric mining vehicle comprising: at least one electric traction motor configured to drive at least one wheel on a front axle or a rear axle of the electric mining vehicle; a battery system comprising a first battery portion, a second battery portion; each battery portion comprising one or more battery cells, one or more thermal management system (TMS), one or more main electric box (MEB) and one or more high power DC-DC module; wherein said first battery portion and said second battery portion are adapted for simultaneous providing of an electric power flow to said at least one electric traction motor; and wherein said electric power flow to and / or from the first battery portion and / or the second battery portion being controlled by at least one high power DC-DC module.110602pc 14 5. The electric mining vehicle according to claim 4, wherein said first battery portion comprising a first TMS and a first MEB and said second battery portion comprising a second TMS and a second MEB.

6. The electric mining machine according to any one of claim 4-5, wherein a first battery portion is connectable to a first battery charger and a second battery portion is connectable to a second battery charger.

7. A method for controlling electric power flow in a battery system for powering at least one electric traction motor of a mining vehicle, the battery system comprising a first battery portion, a second battery portion; each battery portion comprising one or more battery cells, one or more thermal management system (TMS), one or more main electric box (MEB) and one or more high power DC-DC module; wherein said first battery portion and said second battery portion are adapted for simultaneous providing of an electric power flow to said at least one electric traction motor, said method comprising the step of: - controlling said electric power flow to and / or from at least one battery portion with at least one high power DC-DC module provided in the electric power flow between said first and second battery portions or from at least one battery portion and said electric traction motor and thereby controlling at least one of State Of Charge (SOC) and / or charge rate of said first and / or said second battery portion.

8. The method according to claim 7, further comprising the step of controlling the temperature of the battery system with a first thermal management system (TMS1) for the first battery portion and a second thermal management system (TMS2) for the second battery portion.

9. The method according to any one of claim 7 or 8, further comprising the steps of: - charging the first battery portion with a first battery charger, - charging the second battery portion with a second battery charger.110602pc 15 10. The method according to claim 9, wherein said first and second batteries are charged simultaneously.

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