A battery module, a battery pack, and a vehicle comprising the battery pack

Abstract

A battery module (170) is presented. The battery module comprises multiple battery cells (110), and multiple connections (120) to at least one electrically sensitive circuit (130). Each of the multiple connections (120) comprises at least one component (121, 122) coupled in series between a battery cell (110) and an electrically sensitive circuit (130), the at least one component (121, 122) having an enhanced inductance (L) preventing a transient electric energy (141) to propagate from the battery module (170) to the electrically sensitive circuit (130), thereby redirecting the transient electric energy (142) to the multiple battery cells (110). Each one of the multiple battery cells (110) is configured to comprise an internal resistance (111) which is utilized for dissipating a portion (143) of the transient electric energy (142) being redirected to the battery cell (110). Hereby, the transient electric energy is safely dissipated by the multiple battery cells (110) of the battery module (170).

Description

[0001] A BATTERY MODULE, A BATTERY PACK, AND A VEHICLE COMPRISING THE BATTERY PACK

[0002] Technical field

[0003] The present invention relates to a battery module, and more specifically to a battery module protecting an electrically sensitive circuit against transient electric energy. The present invention further relates to a battery pack comprising at least one battery module and at least one electrically sensitive circuit, and to a vehicle comprising the battery pack.

[0004] Background

[0005] The following background description constitutes a description of the background to the present invention, which does not, however, necessarily have to constitute prior art.

[0006] Electric energy is used in many applications nowadays. In the following, vehicle applications of electrical energy usage are mainly described as examples when explaining the herein presented aspects and embodiments. However, the herein described aspects and embodiments may be generally applicable to any application comprising one or more battery modules and electrically sensitive circuits.

[0007] In vehicles, electric energy is for example used for driving traction motors, and is possibly also used for driving other motors in the vehicle, such as e.g. fan motors or pump motors of a cooling system. Electric energy may also be used for driving other electrical components in the vehicle, such as e.g. control units, lights or displays. The vehicle therefore comprises at least one battery pack, which comprises one or more battery modules. A battery pack used for driving e.g. a traction motor is a high voltage system positioned in a high voltage environment, for example a voltage class B system / environment. In such high voltage systems / environments, electric energy transients / spikes may occur due to static discharges in or around the battery pack. Such spikes / transients are the result of quick changes of voltage potentials within the battery pack.

[0008] The battery pack further comprises one or more circuits connected to the battery cells of the battery pack, and these one or more circuits can be configured to perform for example measurements and balancing of the battery cells. Thus, one or more parameters of the battery module may be monitored by the one or more circuits, and then balancing of state of charge (SoC) levels of the battery cells in the battery pack may be controlled based on these measurements. The measuring and balancing circuits are generally sensitive to electric energy transients, and therefore need to be protected.

[0009] Brief description of the invention

[0010] Some conventional solutions for protection against electric energy transients / spikes utilize a component, such as e.g. a transient voltage suppression (TVS) diode or a capacitor bank, coupled in parallel with the circuit to be protected. For example, the TVS diode allows the current to run through the TVS diode instead of through the circuit if the voltage over the TVS diode exceeds a certain voltage threshold, and stops the current from running through the TVS diode if the voltage over the TVS diode decreases to a level below the voltage threshold. The TVS diode continues to bypass current until the electric energy transient has been absorbed, or until it breaks.

[0011] The conventional solutions thus comprise parallel coupled electronic protection components, such as TVS diodes and / or capacitor banks, dedicated for absorbing and / or bypassing the electric energy transients / spikes. These electronic protection components have to be bulky to be able to cope with the high voltages and currents of the electric energy transients / spikes. The electronic protection components are also relatively costly to produce, and to install and / or replace. In many applications, such as in vehicle applications, a large number of such electronic protection components would be needed for protecting the sensitive circuits, wherefore the costs and the space needed to provide sufficient protection would also be multiplied with the number of protection components. As is well known in the field, there is generally a shortage of available space in battery modules / packs.

[0012] It is therefore an objective of the present invention to provide a battery module such that these problems are at least partly solved.

[0013] According to an aspect of the present invention, this objective is achieved through the above-mentioned battery module, which comprises: - multiple battery cells; and

[0014] - multiple connections to at least one electrically sensitive circuit, wherein

[0015] - each of the multiple connections comprises at least one component coupled in series between a battery cell and an electrically sensitive circuit, the at least one component having an enhanced inductance L preventing a transient electric energy to propagate from the battery module to the electrically sensitive circuit, thereby redirecting the transient electric energy to the multiple battery cells;

[0016] - each one of the multiple battery cells is configured to comprise an internal resistance which is utilized for dissipating a portion of the transient electric energy being redirected to the battery cell; and

[0017] - the multiple battery cells are configured to dissipate the redirected transient electric energy internally within the multiple battery cells.

[0018] In the presented battery module, the transient electric energy is redirected to the battery cells to be dissipated therein. The battery cells are much better equipped, i.e. are more robust and resistant, regarding high voltages and / or currents than any other electronic component in the high voltage system. The battery cells are also much more robust than the TVS diodes and the capacitor packs used in conventional solutions. The capacity for absorbing / dissipating electric energy in the battery cells is notable and considerable. There is therefore only a minimal risk that the battery cells will be damaged due to high voltages and / or currents. Thus, the presented battery module is much more robust against transient electric energies than conventional solutions were.

[0019] Also, the presented solution reduces the physical space needed to protect the sensitive circuits against the transient electric energies. For example, bulky diodes or capacitor packs can be avoided, and / or less printed circuit board (PCB) space / area is needed compared to conventional solutions, which also reduces the cost for the protection.

[0020] The space and costs saved by the presented solution, in relation to conventional solutions, increase with the number of connections / paths to the battery module. Generally, for a higher number of connections, there are more components and longer cabling in the system. Hereby, the number of possible points of failure increases, and the disruptive transients may become worse. The presented solution provides a simple protection also for such systems and is thus increasingly cost effective with an increasing number of connections.

[0021] The at least one component providing the enhanced inductance, which is coupled in series with the electrically sensitive circuit according to the presented solution, increases the impedance of the path to the electrically sensitive circuit for electric energy transients / pulse / spikes, such that the electric energy transients go through the battery cells instead. Thus, the electric energy transients are hereby redirected to the battery cells. More in detail, the enhanced inductance of the at least one component resists rapid changes in currents. If the rate of current through the inductor is changed, a voltage is induced that resists the current flow. Thus, a high voltage will then build up over the enhanced inductance, i.e. between the battery cell and the at least one sensitive circuit. This induced voltage stops the current from running to and through the at least one sensitive circuit. Since the current cannot run to the at least one sensitive circuit, it must take another way instead, which is through the battery cells. The cells are resistant against these voltage levels, because they are designed for such corresponding current levels.

[0022] The enhanced inductance of the at least one component thus has a high impedance against rapidly changing electric energy transients, but has a lower impedance against normal balancing currents. Hereby, the balancing paths have a sufficiently low resistance such that a normal balancing current can run through the cell balancing resistances of the electrically sensitive circuit, that will then absorb energy by dissipating heat. However, the balancing paths have a sufficiently high impedance against electric energy transients to protect the electrically sensitive circuit. Thus, since the electric energy transients will run through the path of least resistance, which due to the enhanced inductance of the at least one component is through the battery cells, the transients will run through the battery cells and not through the sensitive circuit. Hereby, the battery cells are slightly charged by the transients, and the electric energy is dissipated over the internal resistances of the battery cells. The battery cells comprise considerable mass of metal, and is robust against high energy levels. The presented solution utilizes the already existing battery cells for dissipation of the transient electric energies, i.e. it does not require any additional energy storages to be able to handle the transient electric energies. This is in contrast to conventional solutions in which separate / external / dedicated / additional energy storages, e.g. in form of space consuming capacitor banks, are needed. This is also in contrast to conventional solutions in which bulky TVS diodes are used for bypassing the energy.

[0023] The balancing paths utilized by the at least one electrically sensitive circuit for controlling the balancing of state of charge levels of the multiple battery cells have in conventional solutions been sensitive to transient electric energies. By the presented solution, the at least one electrically sensitive circuit, including all these balancing paths, is protected against the transient electric energies. Hereby, a more robust balancing of the state of charge levels of the multiple battery cells is provided.

[0024] Since the multiple battery cells are configured to dissipate the redirected transient electric energy internally within the multiple battery cells, the already existing battery cells are utilized for dissipation of the transient electric energies, whereby no additional mechanisms / components taking up valuable PCB space are required to handle the transient electric energies. The battery cells are robust, and have a considerable capacity for absorbing / dissipating electric energy. There is therefore no risk that the battery cells will break due to high voltages and / or currents. Also, no additional space is needed in the battery module to protect the sensitive circuits against the transient electric energies.

[0025] According to an embodiment of the present invention, each of the at least one component is one in the group of:

[0026] - a ferrite core inductor;

[0027] - a coil inductor;

[0028] - a printed circuit implemented inductor.

[0029] By utilizing e.g. a ferrite core conductor or a coil inductor in the at least one component providing the enhanced inductance L, the cabling and / or connections between the battery cells and the sensitive circuit of the cell module controller can be made as short as possible. Short cabling and / or connections enhances the accuracy of the battery cell measuring and battery cell balancing performed by the cell module controller. Short cabling and / or connections also save costs and implementation space, and reduce the cable mass.

[0030] According to an embodiment of the present invention, the enhanced inductance L of the at least one component is one in the group of:

[0031] - L < 1 mH; and

[0032] - 1 pH < L < 50 pH.

[0033] These values for the enhanced / additional inductance L of the at least one component provides for a safe protection of the electrically sensitive circuit by redirection of the electric energy transients to the battery cells. These values for the enhanced inductance L also distinguishes the enhanced inductance L of the at least one component and from any possible parasitic inductance in the system.

[0034] According to an embodiment of the present invention, the at least one component and the electrically sensitive circuit coupled in series form a low pass filter.

[0035] Hereby, the electric energy transients, that have higher frequency components, are blocked / stopped by the formed low pass filter, such that they do not reach the electrically sensitive circuit.

[0036] According to an embodiment of the present invention, the battery cell, the at least one component, and the electrically sensitive circuit coupled in series form one in the group of:

[0037] - a loop comprising the battery cell, one component having the enhanced inductance L, and the electrically sensitive circuit; and

[0038] - a loop comprising the battery cell, a first component having a first portion L1 of the enhanced inductance L, the electrically sensitive circuit, and a second component having a second portion L2 of the enhanced inductance L.

[0039] Thus, depending on the implementation, the enhanced inductance L may be provided by one or two components being coupled in series with the electrically sensitive circuit. Hereby, a loop suitable for the specific implementation may be selected, such that the protection of the electrically sensitive circuit is adapted to the battery pack in which it is comprised.

[0040] According to an embodiment of the present invention, the battery module is configured to, via at least one of the multiple connections, supply power for driving the at least one electrically sensitive circuit.

[0041] Thus, the battery module and its multiple battery cells provide the at least one electrically sensitive circuit with both power supply and protection against electric energy transients. Hereby, the battery pack can be made in a compact format, i.e. in a small size.

[0042] According to an embodiment of the present invention, the battery module is configured to distribute the redirected transient electric energy over the multiple battery cells.

[0043] Thus, instead of dissipating all the electric energy of the transient over one cell balancing resistance, which could probably damage the cell module controller, the electric energy will, by the utilization of the at least one component having an enhanced inductance, be spread over the battery cells, e.g. will be spread among all of the battery cells, of the battery module. Hereby, each battery cell will only have to cope with, i.e. dissipate, a portion of the totally redirected electric energy transients. A robust protection against electric energy transients is hereby provided.

[0044] According to an embodiment of the present invention, the battery module is configured to distribute the transient electric energy such that a portion of the transient electric energy being dissipated by a battery cell is essentially inversely proportional to a distance between a point of origin of the transient electric energy and the battery cell.

[0045] Thus, a battery cell being further away from the spark, i.e. from the point of origin of the transients, has to dissipate less energy than a battery cell being closer to the point of origin. The electric energy is therefore distributed unevenly over the battery cells. The energy being dissipated in each battery cell is, in other words, reduced with an increasing distance from the origin of the transients. For example, there may be an essentially linearly decreasing relationship between the dissipated energy in a battery cell and the distance from the discharge point to the cell. The transient electric energies being rapidly decreasing with increasing distances from the point of origin minimize the risk for damages, especially for electronic components positioned further away from the point of origin.

[0046] According to an embodiment of the present invention, the portion of the transient electric energy is dissipated into heat by the internal resistance of the battery cell.

[0047] The battery cells and their internal resistances are robust against high voltages and / or currents, and have a considerable capacity for absorbing / dissipating electric energy into heat. It is therefore highly unlikely that the battery cells will become damaged or break due to the high voltages of the transients.

[0048] According to an embodiment of the present invention, the battery module is configured to work in a voltage class B environment of a vehicle.

[0049] The battery module may therefore be implemented in essentially any electrically or partially electrically driven vehicle comprising a voltage class B environment.

[0050] According to an aspect of the present invention, the objective is achieved through a battery pack, which comprises:

[0051] - at least one herein presented battery module; and

[0052] - the at least one electrically sensitive circuit, wherein the at least one electrically sensitive circuit is configured to perform measurements of one or more parameters of the battery module and to control balancing of state of charge levels of the multiple battery cells based on the measurements.

[0053] The battery pack has the advantages mentioned for the battery module.

[0054] According to an embodiment of the present invention, the one or more measured parameters comprise one or more in the group of:

[0055] - at least one cell voltage V of at least one battery cell;

[0056] - at least one state of charge SoC value of at least one battery cell; and

[0057] - at least one temperature value T of the battery module. Hereby, an accurate and efficient battery cell balancing can be performed based on the one or more measured parameters.

[0058] According to an embodiment of the present invention, the battery pack further comprises:

[0059] - a cell module controller comprising the at least one electrically sensitive circuit.

[0060] The cell module controller is configured to measure the one or more parameters of the battery module and to perform an accurate and efficient battery cell balancing based on the one or more measured parameters. Hereby, an improved reliability and lifetime of the battery cells, and thus of the battery back, is provided.

[0061] According to an aspect of the present invention, the objective is achieved through a vehicle comprising a herein described battery pack.

[0062] The vehicle has the advantages mentioned for the battery pack and battery module.

[0063] Brief list of figures

[0064] Embodiments of the invention will be illustrated in more detail below, along with the enclosed drawings, where similar references are used for similar parts, and where:

[0065] Figure 1 schematically illustrates an example vehicle, in which embodiments of the present invention may be implemented,

[0066] Figure 2 schematically illustrates some parts of an example battery module according to some embodiments of the present the invention,

[0067] Figure 3 schematically illustrates a prior art solution, and

[0068] Figure 4 schematically illustrates some parts of a battery pack and a battery module according to various embodiments of the present invention.

[0069] Description of preferred embodiments

[0070] Figure 1 schematically shows an exemplary heavy vehicle 500, such for example a truck or a bus, which will be used to explain the herein presented solution and its aspects and embodiments. The aspects and embodiments are, however, not limited to use in vehicles as the ones shown in figure 1 , but may also be used in lighter vehicles, such as cars or other types of vehicles.

[0071] A vehicle 500, as shown schematically in Figures 1 , comprises multiple wheels, of which at least one pair comprises drive wheels 503, 504. The vehicle 500 furthermore comprises a powertrain 502 configured to transfer a torque between at least one power source 501 , such as e.g. at least one electric machine 501 , or a combination of a combustion engine and at least one electric machine 501 , implementing a so-called hybrid drive, to the at least one pair of drive wheels 503, 504. The at least one electric machine 501 is provided with electrical energy by at least one battery pack 180 coupled to the at least one electric machine 501 , and is controlled by at least one control unit / device / system 511 . The battery pack 180 is also controlled by a control unit / device / system 511. In figure 1 , the control unit / device / system 511 is illustrated as one single unit / device / system. However, as is understood by a skilled person, the unit / device / system 511 may be implemented by utilization of essentially any number of units / devices / systems.

[0072] The torque provided by the power source 501 may be provided to the at least one pair of drive wheels 503, 504 via a central gear, such as e.g. a customary differential, and drive shafts connected with the central gear. One or more electric machines 501 may also be arranged essentially anywhere in the vehicle 500, as long as the produced torque is provided to the drive wheels 503, 504, e.g. adjacent to one or more of the drive wheels 503, 504, as is understood by a skilled person.

[0073] The vehicle may be braked by utilizing the power source 501 , i.e. by utilizing regenerative braking. The vehicle 500 may further include at least one braking arrangement arranged at each one of the wheels of the vehicle, where the at least one braking arrangement may be included in a braking system.

[0074] The control unit / device / system 511 may be configured for controlling the one or more electric machines 501 , and one or more of the at least one battery pack 180, the braking system and other suitable systems and / or components of the vehicle 500. However, in figure 1 , only the units / devices / entities of the vehicle useful for understanding the present invention are schematically illustrated. The battery pack 180 may comprise one or more battery modules 170. Each battery module 170 may comprise one or more battery cells 110. The battery pack 180 may be configured in a large number of ways. As a non-limiting example, the battery pack 180 may comprise 180 battery cells 110 in total, where these 180 battery cells 110 are arranged in 10 battery modules 170. Thus, each battery module 170 then comprises 18 battery cells 110 coupled in series, and a cell module controller 190 thus has 18 connections to each battery module 170, one to each battery cell 110. As another non-limiting example, the battery pack 180 may comprise 15 battery modules 170, where each battery module then comprises 12 battery cells 110. It should be noted that the battery pack 180 may comprise essentially any number of battery cells 110, arranged in any number of battery modules 170. The herein presented solution is generally applicable on any such battery pack 180.

[0075] The battery pack 180, and its battery modules 170 may, according to some embodiments, be configured to work in a high voltage environment, for example in voltages exceeding 60 Volt, which may also be classified as a voltage class B environment, for example in a vehicle 500. The system voltages in such high voltage environments may reach high levels, for example 800 Volt or more. The battery pack 180, and its battery modules 170 may, according to other embodiments, be configured to work in a lower voltage environment, for example below 60 Volt, which may be classified as a voltage class A environment.

[0076] The battery pack 180 further comprises at least one electrically sensitive circuit 130. As explained below, the at least one electrically sensitive circuit 130 is configured to perform measurements in the battery pack 180, e.g. in the one or more battery modules 170, and to perform passive balancing of state of charge levels over the one or more battery cells 110 of the one or more battery modules 170. The electrically sensitive circuit 130 may also be configured to provide alerts / warnings in case of overvoltages or undervoltages in a battery module 170, or in case of over temperatures or under temperatures in a battery module 170 or in the battery pack 180.

[0077] The electrically sensitive circuit 130 may at least partially be comprised in and / or may at least partially be part of a cell module controller (CMC), also called cell monitoring circuit (CMC) 190. There is a general problem in battery modules 170 that, after a number of charging and discharging cycles, the battery cells start to drift from each other regarding their state of charge levels. The battery cells 110 thus get unbalanced, although being initially well balanced. In the cell balancing procedure, the battery cells 110 having higher state of charge levels are passively discharged, in an effort to make the battery cells 110 essentially balanced during their lifetime, as far as possible. By the performed cell balancing, it is prevented that a battery cell is discharged under an undervoltage threshold for the battery, and that it is charged over an overvoltage threshold for the battery cell during its charge and discharge cycles. The state of charge balancing of the battery cells 110 performed by utilization of the cell module controller 190 improves the reliability and lifetime of the battery cells 110.

[0078] The cell module controller 190, and therefore also the electrically sensitive circuit 130, is located within the battery pack 180, and is arranged externally and / or internally on the battery module 170. The cell module controller 190 has two main functions, it performs battery cell monitoring, including cell module temperature measurements, and performs battery cell balancing. Measurements of battery cell voltages may be periodically performed, and the measured values may be reported to a connected control unit, such as a battery module controller (BMC) or a master electronic control unit (ECU). The cell module controller 190 is also configured for balancing the battery cells, such that they during their lifetime have relatively equal levels of state of charge. For example, the electrically sensitive circuit 130, possibly being comprised in the cell module controller 190, may provide / report measurements of e.g. cell voltages, state of charge levels for cells and / or temperatures values for the battery module 170 to the battery module controller, which then commands the cell module controller 190 to balance the battery cells 110 in the modules 170. The cell balancing being performed may be so-called passive cell balancing, which utilizes a cell balancing resistance connected to the battery cell 110 in order to dissipate energy as heat.

[0079] The cell module controller 190 is a safety critical component, because it is the only component which measures / monitors the voltages and temperatures of the battery cells 110 of the cell module 170, where the temperature monitoring utilizes temperature sensors arranged in the battery cells. High accuracy is needed for the voltage and temperature measurements in order to be able to perform efficient and sufficient battery cell balancing.

[0080] To be able to perform measurements and battery cell balancing, the cell module controller 190 is connected to the battery module 170, more in detail to each of the multiple battery cells 110 of the battery module 170. Since the cell module controller 190 is comprised in the battery pack 180, and is also empowered by the battery cells 110, it is working completely in the environment of the battery module 170 and the battery pack 180, i.e. in the high voltage system. This is an aggressive environment for the cell module controller 190 to operate in. In this high voltage environment / domain, high levels of electric energy, originating from various sources, may occur. For example, there are high levels of electric energy running to and from the electric traction motors, and also to and from other electric motors in the vehicle, e.g. for cooling, that may cause transient electric energies. Transient electric energies may also be caused by rapid electrostatic shifts in the battery pack 180, i.e. by voltage potentials changing quickly in the battery pack 180. Such transient electric energies may reach voltage levels e.g. in the range of 500-10.000 Volt. Electrostatic shifts may for example be the result of malfunctioning components or software bugs for contactors / switches used for connecting the battery cells 110 to electrical vehicle systems and / or to charging stations.

[0081] An application-specific integrated circuit (ASIC) of the cell module controller 190 often comprises metal oxide semiconductor field-effect transistors (MOS-FETs) acting as switches used for directing balancing currents to run through the cell balancing resistors. The cell balancing resistances, i.e. the cell balancing resistors, used for the cell balancing are connected to the metal oxide semiconductor field-effect transistors and are comprised in the cell balancing circuit / path. When an electric energy transient occurs in a battery module 170, the paths through the cell balancing resistors are the paths of lowest resistance. Thus, the electric energy transient will therefore try to run through the metal oxide semiconductor field-effect transistors, being used as a switches, and to the cell balancing resistors, where the metal oxide semiconductor field-effect transistors are susceptible to electric energy transients, as explained in the following. There is a large number of cell balancing resistors and metal oxide semiconductor field-effect transistors in the cell module controller 190. The cell balancing resistors and metal oxide semiconductor field-effect transistors therefore need to be small in size and low-cost. However, this also make these components weak and not designed to cope with high voltages. Although the transients are often short in time, in the range of milliseconds, their voltages are much higher than the voltages for which the metal oxide semiconductor field-effect transistors are designed. Thus, a metal oxide semiconductor field-effect transistor being hit by an electric energy transient will break, usually by its source S and drain D connectors being shorted circuited together, whereby the metal oxide semiconductor field-effect transistor stops working as a switch and stays low-ohmic. After this, the battery cell connected to this metal oxide semiconductor field-effect transistor is always discharged over its cell balancing resistance, regardless of how the control unit tries to control the cell. The state of charge level of the cell will hereafter be too low, such that the battery module has to be exchanged / replaced.

[0082] Thus, when transient electric energies hit the cell module controller 190, components of the cell module controller 190, such as MOS-FETs or other sensitive components, may get short circuited, and the cell module controller 190 cannot perform its measuring and balancing duties anymore. Thus, the electric energy transients occurring in the battery pack 190 may break the cell module controller 190.

[0083] Figure 2 schematically illustrates a battery module 170 according to some embodiments of the herein presented solution. The battery module 170 comprises multiple battery cells 110, of which one battery cell 110 is shown in figure 1 in order to explain the herein presented aspects and embodiments. Each battery cell 110 has an inherent internal resistance 111 and an internal inductance 112. The battery module 170 further comprises multiple connections 120 to at least one electrically sensitive circuit 130, of which one such connection 120 is shown in figure 1. According to an embodiment, the battery module 170 is configured to supply power for driving the at least one electrically sensitive circuit 130. The power utilized for driving the at least one electrically sensitive circuit 130 is then provided to the at least one electrically sensitive circuit 130 via at least one of the multiple connections 120. According to the herein presented solution, each of the multiple connections 120 comprises at least one component 121 , 122 coupled in series between a battery cell 110 and an electrically sensitive circuit 130. Thus, as illustrated in figure 1 , the battery cell 110 is connected to the electrically sensitive circuit 130 via a connection 120 to the electrically sensitive circuit 130. As mentioned above, the electrically sensitive circuit 130 may be configured to perform measurements and / or balancing of the battery cells 110, and are generally sensitive to electric energy transients.

[0084] Therefore, the series coupled at least one component 121 , 122 of the connection 120 has an enhanced inductance L designed for preventing a transient electric energy 141 to propagate from the battery module 170 to the electrically sensitive circuit 130. The enhanced inductance L is in this document defined as an additional inductance of the at least one component 121 , 122. Thus, the enhanced inductance L is a non- parasitic / non-intrinsic inductance. The enhanced inductance L is a component- caused inductance provided by the at least one component 121 , 122. The enhanced inductance L would therefore not exist in the connection 120 if the at least one component 121 , 122 would be omitted / removed from the connection 120.

[0085] According to an embodiment, the enhanced inductance L of the at least one component 121 , 122 has a value of less than 1 mH; L < 1 mH. According to an embodiment, the enhanced inductance L of the at least one component 121 , 122 has a value between 1 pH and 50 pH; 1 pH < L < 50 pH. According to various embodiments, the at least one component 121 , 122 providing the enhanced inductance L may be a ferrite core inductor, a coil inductor and / or a printed circuit implemented inductor, depending on the implementation.

[0086] According to an embodiment, which is schematically illustrated in figure 2, the connection 120 comprises a first component 121 having a first portion L1 of the total enhanced inductance L and a second component 122 having a second portion L2 of the total enhanced inductance L. Hereby, the battery cell 110, the series coupled first component 121 having the first portion L1 of the enhanced inductance L, the series coupled electrically sensitive circuit 130, and the series coupled second component 122 having the second portion L2 of the enhanced inductance L together form a series coupled loop. The first L1 and second L2 portions of the enhanced inductance L here together make up the total enhanced inductance L; L1 + L2 = L. According to another embodiment, the connection 120 comprises a single component 121 having the total enhanced inductance L. Hereby, the battery cell 110, the series coupled component 121 having the total enhanced inductance L, and the series coupled electrically sensitive circuit 130 together form a series coupled loop.

[0087] The enhanced inductance L provided by the series coupled at least one component 121 , 122 prevents / blocks / restricts / stalls the transient electric energy 141 to propagate from the battery module 170 to the electrically sensitive circuit 130. Hereby, the transient electric energy is redirected 142 to the multiple battery cells 110 instead, illustrated by one battery cell 110 in figure 1 . The battery cell 110 is configured to comprise an internal resistance 111 , which is utilized for dissipating a portion 143 of the transient electric energy being redirected 142 to the battery cells 110 by the series coupled at least one component 121 , 122. The multiple battery cells 110 of the battery module 170 are configured to together dissipate the redirected transient electric energy 142 internally within the multiple battery cells 110, i.e. within the battery module 170. According to an embodiment, the portion 143 of the transient electric energy 142 being redirected into a battery cell 110 is dissipated into heat by the internal resistance 111 of the battery cell 110.

[0088] The series coupled at least one component 121 , 122, and its enhanced inductance L, thus causes the transient electric energy 141 to turn around, and instead of reaching the electrically sensitive circuit 130 and its cell balancing resistance 131 , which would destroy the electrically sensitive circuit 130, the transient electric energy is redirected 142 to the battery cell 110. The battery cell 110 is much better equipped for absorbing the redirected transient electric energy 142 than the electrically sensitive circuit 130, wherefore the battery cell 110 can cope with high voltages and currents. As mentioned above, the battery module 170 and the battery cells 110 may for example be configured / designed to work in a voltage class B environment of a vehicle 500.

[0089] Figure 3 schematically shows a conventional protection against electric energy transients, which is presented to clearly illustrate the novel features of the herein presented solution. According to the conventional protection shown in figure 3, a TVS diode 220 is coupled in parallel with the electrically sensitive circuit 130 to be protected. When electric energy transients 241 occur, they run in a loop 241 , 242, 243 through the TVS diode 220. The TVS diode 220 starts bypassing current through it when the voltage over it exceeds a certain voltage threshold, and continues to bypass the current until the voltage over the TVS diode decreases to a level below the voltage threshold, or until the TVS diode 220 eventually breaks due to overheating. When the TVS 220 is broken, the electrically sensitive circuit 130 is left unprotected, and is thus susceptible to transient energy damage. Thus, the conventional solution comprises a parallel coupled TVS diode 220 which bypasses the electric energy transient until the voltage over it falls below the voltage threshold again. To be able to cope with the high voltage transient electric energies without breaking, the TVS diode 220 has to be of a certain size, since its capacity to handle electric energies depends on, and is proportional to, its size. Thus, the conventional solution needs to use bulky TVS diodes 220, which causes high component costs and shortage of space in the battery pack.

[0090] The herein presented solution shown schematically in figure 2, however, comprises at least one series coupled component 121 , 122 in the connection 120, which is configured for providing an enhanced inductance L. Hereby, the electric energy transients are redirected 142 to the one or more battery cells 110, in which the electric energy transients 142 are absorbed without the one or more battery cells 110 breaking down.

[0091] According to an embodiment, the at least one component 121 , 122 being coupled in series with the electrically sensitive circuit 130, as shown in figure 2, together form a low pass filter, which stops / blocks the transient electric energy from reaching the electrically sensitive circuit 130. The transient electric energy 141 has a higher frequency content than normal balancing currents have, and is therefore stopped / blocked by the formed lowpass filter, although the normal balancing currents are allowed to reach the electrically sensitive circuit 130.

[0092] Figure 4 schematically illustrates one battery module 170 of a battery pack 180. The battery cells 110a, 110b, 110c, 110d, 110e of the battery module 170 are connected in series. Each individual battery cell 110a, 110b, 110c, 110d, 110e has an inherent internal resistance 111a, 111 b, 111 c, 111 d, 111 e and an internal inductance. As mentioned above, and illustrated in figure 4, the battery pack 180 may comprise one or more battery modules 170, and each such battery module 170 may comprise one or more battery cells 110. In the non-limiting example shown in figure 4, the battery module 170 comprises five battery cells 110a, 110b, 110c, 110d, 11 Oe. However, the herein presented aspects and embodiments may be applied to essentially any number of battery cells 110 being comprised in any number of battery modules 170, as is understood by a skilled person.

[0093] Each battery cell 110a, 110b, 110c, 110d, 110e comprises its internal resistance 111a, 111 b, 111 c, 111 d, 111 e, and is connected to at least one electrically sensitive circuit 130, which may be comprised in and / or may at least partially be part of a cell module controller 190 of the battery pack 180. The at least one electrically sensitive circuit 130 may in this example comprise five cell balancing resistances 131a, 131 b, 131c, 131 d, 131 e, one cell balancing resistance connected to each battery cell 110a, 110b, 110c, 11 Od, 110e to be able to provide balancing of the state of charge level for the battery cell 110a, 110b, 110c, 110d, 11 Oe. The battery module 170, the at least one electrically sensitive circuit 130 and the connections between them may be denoted, i.e. may be arranged in, a cell module assembly 175.

[0094] The battery module 170 and the battery back 180 are arranged in a so-called isolated terra (IT) or floating environment, i.e. is not connected to the rest of the vehicle, and is not coupled to the ground / earth 160 of the vehicle. These parts of the high voltage system, i.e. the battery pack 180 and the battery modules 180, are thus not allowed to come in contact with e.g. the chassis of the vehicle. This is illustrated by the capacitive barrier 161 between the battery module 170 and battery pack 180 and / or the vehicle ground / earth 160. The capacitive barrier 161 has a parasitic capacitive property caused by a non-conducting material, such as non-conducting film, glue, or the like, located between the battery module 170 and the battery pack 180 and / or the vehicle ground / earth 160. The parasitic capacitance to ground / earth 160 is in figure 4 illustrated as capacitances 161a, 161b, 161c, 161 c, 161d, 161 e, 162a between the battery cells 110a, 110b, 110c, 110d, 110e and the battery pack 180 and / or ground / earth 160. Energy in the form of high voltages may be stored in the capacitive barrier 161. In the non-limiting example shown in figure 4, there is a short circuit over the parasitic capacitance 161c, i.e. there is some kind of breakdown in the isolation barrier 161 at that point. This short circuit causes a discharge 165 of a voltage spark illustrated as a flash. The short circuit causes the electric potential of the point below the flash to go to 0 Volts, i.e. the point below the flash is grounded, when the rest of the points of the battery module 170 are still at high voltages, e.g. 3000 Volts or more. Therefore, large charges start to move within the battery pack 180, trying to even out the differences in charges / voltages within the battery pack 180. This results in electric energy transients 141 running through the battery module 170 aiming to even out these voltage differences. According to the herein presented solution, at least one component 121a, 121b, 121c, 121 d, 121 e, 122a comprising an enhanced inductance L is configured in each connection 120a, 120b, 120c, 120c, 120d, 120e between battery cells 110a, 110b, 110c, 110d, 110e and the at least one electrically sensitive circuit 130.

[0095] The at least one component 121 a, 121 b, 121 c, 121d, 121e, 122a comprising an enhanced inductance L, being connected in series between the battery cells 110a, 110b, 110c, 11 Od, 110e and the at least one electrically sensitive circuit 130, efficiently stops / blocks the electric energy transients 141 from reaching the at least one electrically sensitive circuit 130. More specifically, the at least one component 121a, 121 b, 121 c, 121d, 121e, 122a stops / blocks the electric energy transients to reach the cell balancing resistances 131a, 131 b, 131c, 131d, 131e to which the battery cells are connected.

[0096] The electric energy transients are, due to the at least one component 121a, 121b, 121c, 121 d, 121 e, 122a, instead redirected to run through the battery cells 110a, 110b, 110c, 110d, 110e. This is illustrated as discharge currents 143a, 143b, 143c, 143d, 143e running through the battery cells 110a, 110b, 110c, 110d, 110e, respectively. The internal resistances 111a, 111 b, 111c, 111 d, 111 e of the battery cells 110a, 110b, 110c, 110d, 110e will hereby dissipate the electric energy transients, without breaking or being otherwise damaged.

[0097] According to an embodiment, the battery module 170 is configured to distribute the redirected transient electric energy 142 over the multiple battery cells 110 of the battery module 170, such that a portion 143a, 143b, 143c, 143d, 143e of the redirected electric energy transient 142 is dissipated in each battery cell 110a, 110b, 110c, 110d, 110e.

[0098] The battery module 170 may be configured to provide various kinds of distribution of the redirected electric energy transient 142 over the battery cells 110a, 110b, 110c, 110d, 11 Oe. For example, the battery module 170 may be configured to aiming for an even distribution of the redirected electric energy transient 142 over the battery cells 110a, 110b, 110c, 110d, 110e.

[0099] According to an embodiment, the battery module 170 is configured to unevenly distribute the transient electric energy 142, such that a portion 143 of the electric energy transient 141 being dissipated by a battery cell 110 is essentially inversely proportional to a distance between a point of origin 165 of the transient electric energy 141 and the battery cell 110. Thus, for the example schematically illustrated in figure 4, where the point of origin 165 of the electric energy transient 141 is the third capacitance 161c connected to the third battery cell 110c, the third portion 143c of the 143 of the electric energy transient 141 being dissipated by the third battery cell 110c is larger than the first portion 143a being dissipated by the first battery cell 110a, because the third battery cell 110c is located closer to the short circuit in the third capacitance 161 c than the first battery cell 100a is. Thus, the further away from the point of origin 165 a battery cell is, the smaller the portion of the electric energy transient being dissipated in that battery cell will be.

[0100] It should be noted that if the cell module controller 190 including the at least one electrically sensitive circuit 130 in figure 4 would be left unprotected, which traditionally has sometime been the case, there would be no components 121 a, 121 b, 121 c, 121 d, 121 e, 122a having enhanced inductances coupled in series between the battery cells 110a, 110b, 110c, 110d, 110e and the resistances 131 a 131 b, 131 c, 131 d, 131 e of the at least one electrically sensitive circuit 130. Therefore, the electric energy transients would for such a conventional solution run through the resistances 131 a 131 b, 131 c, 131 d, 131 e of the at least one electrically sensitive circuit 130 and cause a destructive power dissipation over these resistances 131a 131 b, 131c, 131 d, 131e until the sensitive circuit 130 breaks or is at least partly damaged. Thus, the transient electric energy 141 could then damage the at least one electrically sensitive circuit 130, and thus the cell module controller 190. Such a damage, and potential destruction, of the at least one electrically sensitive circuit 130 of the cell module controller 190 is prevented by the herein presented solution. Also, if the conventional solution illustrated in figure 3 would be implemented in the scheme of figure 4, a costly and bulky TVS diode 220 would have to be arranged in parallel with each one of the resistances 131 a 131 b, 131c, 131 d, 131 e of the at least one electrically sensitive circuit 130, which would take up a lot of valuable space in the battery pack 180. The present invention is not limited to the above described embodiments. Instead, the present invention relates to, and encompasses all different embodiments being included within the scope of the independent claims.

Claims

Claims1. A battery module (170) comprising:- multiple battery cells (110); and- multiple connections (120) to at least one electrically sensitive circuit (130), wherein- each of the multiple connections (120) comprises at least one component (121 , 122) coupled in series between a battery cell (110) and an electrically sensitive circuit (130), the at least one component (121 , 122) having an enhanced inductance (L) preventing a transient electric energy (141) to propagate from the battery module (170) to the electrically sensitive circuit (130), thereby redirecting the transient electric energy (142) to the multiple battery cells (110);- each one of the multiple battery cells (110) is configured to comprise an internal resistance (111 ) which is utilized for dissipating a portion (143) of the transient electric energy (142) being redirected to the battery cell (110); and- the multiple battery cells (110) are configured to together dissipate the redirected transient electric energy (142) internally within the multiple battery cells (110).

2. The battery module (170) as claimed in claim 1 , wherein each of the at least one component (121 , 122) is one in the group of:- a ferrite core inductor;- a coil inductor;- a printed circuit implemented inductor.

3. The battery module (170) as claimed in any one of claims 1-2, wherein the enhanced inductance (L) of the at least one component (121 , 122) is one in the group of:- L < 1 mH; and- 1 pH < L < 50 pH.

4. The battery module (170) as claimed in any one of claims 1-3, wherein the at least one component (121 , 122) and the electrically sensitive circuit (130) coupled in series form a low pass filter.

5. The battery module (170) as claimed in any one of claims 1-4, wherein the battery cell (110), the at least one component (121 , 122), and the electricallysensitive circuit (130) coupled in series form one in the group of:- a loop comprising the battery cell (110), one component (121 ) having the enhanced inductance (L), and the electrically sensitive circuit (130); and- a loop comprising the battery cell (110), a first component (121 ) having a first portion (L1 ) of the enhanced inductance (L), the electrically sensitive circuit (130), and a second component (122) having a second portion (L2) of the enhanced inductance (L).

6. The battery module (170) as claimed in any one of claims 1-5, wherein the battery module (170) is configured to, via at least one of the multiple connections (120), supply power for driving the at least one electrically sensitive circuit (130).

7. The battery module (170) as claimed in any one of claims 1-6, wherein the battery module (170) is configured to distribute the redirected transient electric energy (142) over the multiple battery cells (110).

8. The battery module (170) as claimed in claim 7, wherein the battery module (170) is configured to distribute the transient electric energy (142) such that a portion (143) of the transient electric energy (143) being dissipated by a battery cell (110) is essentially inversely proportional to a distance between a point of origin of the transient electric energy (141 ) and the battery cell (110).

9. The battery module (170) as claimed in any one of claims 1-8, wherein the portion (143) of the transient electric energy (141) is dissipated into heat by the internal resistance (111 ) of the battery cell (110).

10. The battery module (170) as claimed in any one of claims 1-9, wherein the battery module (170) is configured to work in a voltage class B environment of a vehicle (500).

11. A battery pack (180), comprising:- at least one battery module (170) according to any one of claims 1 -10; and- the at least one electrically sensitive circuit (130), wherein the at least one electrically sensitive circuit (130) is configured to perform measurements of one ormore parameters of the battery module (170) and to control balancing of state of charge levels of the multiple battery cells (110) based on the measurements.

12. The battery pack (180) as claimed in claim 11 , wherein the one or more measured parameters comprise one or more in the group of: - at least one cell voltage (V) of at least one battery cell (110);- at least one state of charge (SoC) value of at least one battery cell (110); and- at least one temperature value (T) of the battery module (170).

13. The battery pack (180) as claimed in any one of claims 11-12, further comprising: - a cell module controller (190) comprising the at least one electrically sensitive circuit(130).

14. A vehicle (500) comprising a battery pack (180) according to claim 13.

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