Battery-electric device for use with an electrical consumer

Abstract

Battery-electric device (10) for use with an electrical load (52), comprising: an electrochemical battery cell (12) that can be connected to the electrical consumer (52) and has a cell surface (12A, 12B); a direct air heat pump (14) which is in thermal contact with the cell surface (12A, 12B); a pressure regulator (15) configured to exert a constant pressure on the cell surface (12A, 12B) when the battery cell (12) is connected to the electrical load (52), wherein the connection of the battery cell (12) to the electrical load (52) causes the direct air heat pump (14) to pump a quantity of heat from the battery cell (12); and at least one sensor designed to generate an output voltage signal indicating the amount of heat; characterized by the fact that the heat pump (14) comprises a thermoelectric assembly (TEA) (140, 240) with a thermoelectric solid-state module (TEM) (16), a heat sink (18) and a fan (20) for cooling the TEM (16) in response to a temperature control signal; wherein the battery cell (12) is a pouch cell or a prismatic cell, and wherein the TEA (140, 240) comprises a distributed arrangement of TEAs (140, 240), each individual TEA (140, 240) of the distributed arrangement of TEAs (140, 240) being positioned on a corresponding surface section of the battery cell (12); and where: (i) the at least one sensor comprises an arrangement of heat flux sensors (650), each individual heat flux sensor of the arrangement of heat flux sensors (650) being distributed on the cell surface (12A, 12B) and configured to measure the local heat flux at a corresponding section of the cell surface (12A, 12B); and / or (ii) the heat pump (14) comprises a plurality of heat pumps (14), each of which corresponds to a surface profile of the battery cell (12), the battery cell (12) being a cylindrical battery cell (12) and the plurality of heat pumps (14) comprising a pair of intermeshing thermoelectric assemblies (TEAs) (140, 240) which together enclose the battery cell (12) between them.

Description

INTRODUCTION

[0001] The present invention relates generally to battery monitoring strategies and, more particularly, to a battery-powered device according to the preamble of claim 1 for use with an electrical load, as is known essentially from US 4,314,008 A. Further prior art can also be found in the documents WO 2020 / 188165 A1, WO 2021 / 010335 A1, and JP 2009-104902 A.

[0002] Battery cells are electrochemical energy storage devices used to store electrical energy in an electrical circuit and deliver the stored energy to a connected electrical load. When a battery cell is discharged to the electrical load, such as a rotating electrical machine, a lighting device, or a processor bank, the chemical potential energy stored in the battery cell is converted into a direct current (DC) output voltage. In an electric drive system, for example, the DC output voltage is typically inverted by an inverter module during a discharge process. The resulting alternating current (AC) voltage is then used to power individual phase windings of one or more electric traction motors, power electronics components, or other high-voltage devices.During the charging process of such an electric drive system, the electrical energy supplied to the battery cell via an external charging system or through on-board regeneration is converted into chemical potential energy.

[0003] A given battery cell in a rechargeable battery pack undergoes numerous charge and discharge cycles over its lifetime, both of which often generate significant amounts of heat. Operating a battery cell outside a well-defined temperature range reduces battery performance and shortens its useful life. Furthermore, excessively high battery temperatures can lead to thermal runaway if left unchecked. Lithium-ion battery chemistry is a special type of battery chemistry commonly used to power high-energy devices such as laptops and electric vehicle propulsion motors. During the storage and extraction of energy from modern lithium-ion battery packs, heat is generated through charge transfer, chemical reactions, and the intercalation and deintercalation processes that occur within each individual battery cell in the battery pack.Therefore, the battery-electric systems of mobile and stationary devices are able to monitor and control the thermal state of the battery. SUMMARY

[0004] According to the invention, a battery-powered electric device for use with an electrical consumer is presented, which is characterized by the features of claim 1 or by those of claim 4.

[0005] Disclosed herein are methods and corresponding hardware solutions for measuring and evaluating heat generation in an electrochemical battery cell, e.g., a multi-cell traction battery pack for an electric drive system. In particular, the present teachings relate to the arrangement of direct air-source heat pumps on or adjacent to the main surfaces of electrochemical battery cells with different configurations, e.g., pouch cells, prismatic cells, or cylindrical cells. Other embodiments of the heat pumps under consideration can be implemented, specifically with the heat pumps exemplified here as commercially available thermoelectric assemblies (TEAs). Each TEA, in turn, consists of a solid-state thermoelectric module (TEM), an associated heat sink, and a rotary fan or other application-specific thermoregulator.

[0006] Furthermore, the disclosed solutions may utilize temperature sensors and / or heat flow sensors in conjunction with the aforementioned heat pumps. Alternative implementation examples of the present teachings include: (1) a single direct air-source heat pump and heat sink per battery cell, (2) a distributed array of heat pumps, possibly with different sizes or surfaces, for better heat measurement accuracy and localization / detail, and (3) heat pumps adapted to a characteristic surface profile of the battery cell, e.g., hemispherical TEAs for use with a corresponding cylindrical battery cell.

[0007] As known in the art, calorimeters are scientific measuring instruments often used to quantify heat capacity or determine a heat transfer gradient at a surface of interest. The described battery-electric device, in its various embodiments, acts like a calorimeter to enable rapid response to an applied voltage or to an electrical load upon discharge, both of which in turn result in heat generation at the battery cell level. Furthermore, compared to existing approaches, the battery-electric device described below more accurately determines the heat generation rate distribution for battery cells maintained at a calibrated constant pressure. For this purpose, various pressure control devices are described here for applying and maintaining the constant pressure created by compressing the battery cell.

[0008] The direct air-source heat pumps considered here can optionally comprise a TEA in the form of a solid-state TEM, a corresponding heat sink, and the aforementioned rotary fan. As is known in the art, a solid-state TEM operates freely according to the Peltier effect, whereby an electric current flowing through the TEM generates a current-dependent temperature gradient and vice versa. The generated temperature gradient, in turn, drives the heat from one side of the solid-state TEM to the other. It is therefore possible to use TEAs with integrated solid-state TEMs as local heat pumps within a battery or battery pack, as envisioned here.

[0009] Various embodiments of the present battery-electric device and a host battery system are described below. In one possible embodiment, the battery-electric device is configured to measure heat generation in a specific area and / or in multiple dimensions in a pouch battery cell or a prismatic cell. This is done using an assembly of the direct air heat pumps described above, such as one or more TEAs, and optionally in conjunction with a distributed array of heat flow sensors. Such heat flow sensors measure the heat flow between a corresponding surface of the battery cell and the heat sink. Constant pressure, e.g., about 25 kPa to about 35 kPA in one embodiment, is applied to the battery cell to maintain good surface contact between the TEA(s) and the battery cell and, if appropriate, to enable appropriate aging.The advantages of this particular design include facilitating a rapid response to an applied current or to the electrical load during discharge, both of which result in heat generation at the battery cell level, and enabling the accurate determination of a heat flux area distribution.

[0010] In another possible embodiment, the battery electric device operates via an array of TEAs instead of a single TEA on each side of the battery cell, possibly without the use of one or more heat flow sensors. This optional variant utilizes the heat pump response of the TEA array to directly measure local heat generation. As in the embodiment described above, a constant pressure is applied to the battery cell as a compressive force to ensure adequate contact between the battery cell's inner electrode layers and between the battery cell and the TEA array.

[0011] Yet another embodiment can be implemented for use with cylindrical battery cells and offers similar advantages. One possible approach is for two specially designed hemispherical battery casings to cooperate to enclose the cylindrical battery cell therebetween, thereby enabling efficient heat transfer from the cell surface to the heat sink connected to the casing. The overall heat generation is measured using one or more TEAs and at least one heat flow sensor. The operation of the TEA(s) can be controlled via a bipolar power supply when the battery cell is connected to a main power supply or to an electrical load during the respective charging or discharging operation, i.e.when the main power supply supplies an electrical current or voltage to the battery cell and the electrical load receives a current or voltage from the battery cell.

[0012] In this specific design, the heat flow sensor(s) is / are configured to measure the heat flow as heat is radiated from the battery cell surface to the heat sink, simultaneously with controlling the TEAs. This optional design is suitable for use with cylindrical battery cells to enable a dynamic response to the voltage and current applied by the main power supply and to measure heat generation at the cell level or to control the discharge response of the cell when connected to the applied electrical load. The heat generated for a battery cell with a cylindrical profile can thus be determined by accurately quantifying the amount of heat pumped by the TEAs. Such an approach can be compared to existing calorimeters that measure temperature gradients within a battery cell under adiabatic conditions.In some designs, several battery cells with a cylindrical profile can be connected in parallel to measure the heat generation of a mini-module or a group of cells.

[0013] In a specific embodiment described here, the battery-electric device comprises an electrochemical battery cell, a direct air heat pump, and a pressure regulator. The battery cell can be selectively connected to an electrical load or to a main power supply, as disclosed above, in either the battery cell's discharge or charge mode. The heat pump, which is connected to a cell surface of the battery cell, comprises a heat sink and an operable fan designed to cool the heat pump. The pressure regulator, in turn, is configured to exert a constant pressure on the battery cell during the discharge or charge mode.

[0014] The heat pump can optionally be designed as one or more TEAs, each of the TEAs comprising a solid-state TEM in addition to the above-mentioned heat sink and fan.

[0015] Embodiments of the battery electric device include a processor in communication with the heat pump / TEA, the processor configured to calculate the amount of heat pumped by the battery cell at a given temperature setpoint. The processor controls the bipolar power supply to maintain the temperature setpoint, the processor doing so depending on the amount of heat.

[0016] The battery cell may be a pouch cell or prismatic cell as mentioned above, both designs being well known in the field of battery electric systems. In this case, the TEA may comprise a distributed array of TEAs, the TEAs constituting an embodiment of the heat pump briefly described above. Each individual TEA of the distributed array of TEAs is positioned on a corresponding surface portion of the battery cell. The battery electric device may comprise first and second TEAs, i.e., nominally "top" and "bottom" TEAs when the battery electric device is oriented upright, with the battery cell disposed between the TEAs.

[0017] One aspect of the invention comprises an array of heat flow sensors. The individual heat flow sensors of such an array are distributed over the cell surface and designed to measure the local heat flow at the corresponding surface section.

[0018] In one or more possible embodiments, the battery electric device is characterized by the absence of one or more heat flow sensors. In such an embodiment, the TEA may comprise a plurality of TEAs, each individual TEA corresponding to a surface profile of the battery cell. The battery cell may optionally be embodied as a cylindrical battery cell. In such an embodiment, the TEAs may comprise a pair of interlocking, hemispherical battery housings with a molded heat sink, which collectively enclose the battery cell between them.

[0019] In one or more embodiments, an external process controller may be connected to the processor. The external process controller may be configured to perform a control action with respect to the battery cell in response to the amount of heat. If the battery cell is used as part of a larger battery device, e.g., a traction battery pack for an electric vehicle, the process controller may perform the control action. Suitable control actions include, for example, instructing a change in the energy flow of the battery cell, i.e., adjusting a charge or discharge rate of the battery cell or instructing thermal regulation thereof, initiating maintenance of the battery cell, and / or alerting an operator to a possible thermal or electrical fault in the battery system.

[0020] According to yet another embodiment, a battery system comprises the battery-electric device briefly described above and a processor that communicates with the battery cell and the electrical load. The processor is configured to receive the output voltage signal from the sensor(s) when the battery cell is connected to the electrical load, e.g., a resistive, inductive, capacitive, or impedance load, and to generate an electronic control signal in response to the amount of heat. The electronic control signal, in turn, can initiate a control process with respect to the battery cell.

[0021] Also disclosed is a method for constructing a battery-electric device for use with an electrical load. One embodiment of the present method comprises arranging a plurality of heat flux sensors on a cell surface of an electrochemical battery cell. The method further comprises providing a pair of direct-air TEAs, each having one or more solid-state TEMs, a fan, a heat sink, and a metal plate. The one or more TEMs is / are arranged between the heat sink and the metal plate. Furthermore, in this embodiment, the method comprises positioning the battery cell and the heat flux sensors arranged thereon between the metal plate of each pair of direct-air TEAs and then using a pressure control device to apply a constant pressure to the cell surface.This occurs when the battery cell is connected to the electrical load, as the TEAs actively pump heat to or from the battery cell. A measured output voltage signal indicating the heat quantity is then transmitted to a processor via the multiple heat flow sensors.

[0022] The above features and advantages, as well as other features and associated advantages of this invention, will be readily apparent from the following detailed description of illustrative examples and modes for carrying out the present invention, when read in conjunction with the accompanying drawings and the appended claims. Furthermore, this invention expressly includes combinations and subcombinations of the elements and features described above and below. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1A is a perspective view of a representative battery electric device having a battery cell sandwiched between opposing heat pumps according to one aspect of the invention. Fig. 1B is an exploded view of the Fig. 1A illustrated battery-electric device. Fig. Figure 1C is a side cross-sectional view of the Fig. 1A and Fig. 1B illustrated battery electric device along the section line CC from Fig. 1B. Fig. 2A and Fig. 2B show side views of two possible designs of a pressure regulator that can be used with the battery-electric device from Fig. 1A-1C can be used. Fig. 3 and Fig. 4 show a plan view and an exploded view of a possible embodiment of the Fig. 1A-1C shown battery-powered device. Fig. 5 and Fig. 6 show a schematic top view and side view of an alternative embodiment of the battery-electric device from Fig. 1A-1C. Fig. 7 is an exploded view of an alternative embodiment of the Fig. 1A-6, in which the battery cell has a cylindrical profile. Fig. Figure 8 is a schematic diagram of a monitoring system for use with the battery electric device of Fig. 1A-7. DETAILED DESCRIPTION

[0023] Referring to the drawings, in which like reference numerals refer to like features in the several views, Fig. 1A shows a battery-electric device 10 according to an embodiment of the present invention. The battery-electric device 10 comprises an electrochemical battery cell 12, one or more direct air heat pumps 14, and a pressure control device 15. The battery-electric device 10 described in detail here can be connected to a battery system 50 according to Fig. 8 can be used to accurately measure and evaluate heat generation in the battery cell 12, with electrode tabs 12T protruding from the battery-electric device 10 as cathode and anode extensions of the battery cell 12. Furthermore, the higher accuracy of the present strategy compared to existing approaches enables reliable, longer-term operation of the battery cell 12 and thus benefits a wide variety of applications, particularly drive systems for electric vehicles, laptops and other portable electronic devices, as well as commercial or residential power generation systems.

[0024] In the training presented according to Fig. 1A-1C, where Fig. 1C a cross-sectional view along the section line CC of Fig. 1B, the direct air source heat pumps 14 each include a first and a second thermoelectric assembly (TEA) 140 and 240, which are in thermal communication with a respective cell surface 12A and 12B of the battery cell 12. As illustrated, the battery cell 12 is implemented as an electrochemical pouch cell or an electrochemical prismatic cell and therefore has a relatively flat profile. For simplicity and clarity, the battery cell 12 is illustrated as being completely rectangular and planar, with actual embodiments deviating from this ideal, as is common in the art. The present solutions may also be applied to other configurations of the battery cell 12, including cylindrical configurations according to Fig. 7. Therefore, implementation in accordance with Fig. 1A-1C is only one example of a possible application of the present teaching.

[0025] Each of the first and second TEAs 140 and 240 includes a solid-state thermoelectric module (TEM) 16, as shown in Fig. 1C, a heat sink 18 and a fan 20 for cooling the TEA 140 or 240, ie by circulating ambient air through or relative to the respective heat sink 18. The pressure control device 15 of Fig. 1A is designed to exert a constant pressure (arrows PP) on the battery cell 12 when the battery cell 12 is connected to an electrical load 52. A corresponding example is described below with reference to Fig. 8. In the illustrated embodiment according to Fig. 1A, the battery cell 12 is surrounded by the first and second TEAs 140 and 240, respectively, or is located therebetween. In this arrangement, the constant pressure is achieved by compression of the battery cell 12 (arrow PP), with representative embodiments of the pressure control device 15 in Fig. 2A and Fig. 2B and described below.

[0026] The heat sink 18 from Fig. 1A-1C, e.g., a multi-fin, solid or sintered metal block with sufficient surface area to radiate heat from the battery cell 12 to the environment, may be bonded to or integrally formed with a metal plate 22. A thermal pad 23 made of a thermally conductive material, e.g., a silicone-based material or other material suitable for the application, may be disposed adjacent to the metal plate 22 to optimize heat conduction between the battery cell 12 and the first and second TEAs 140 and 240.

[0027] As in Fig. 1B, the second TEA 240 represents the configuration of the first TEA 140, so that the description of the second TEA 240 applies to the structure of the first TEA 140. Some embodiments of the battery-electric device 10 of Fig. 1A may optionally include an array 65 of heat flow sensors 650. The individual heat flow sensors 650 are arranged with respect to different areas of the battery cell 12 from Fig. 1A, so that each heat flow sensor 650 is designed to measure the local heat flow at a corresponding part of the cell surface 12A or 12B. In some cases, a flexible graphite plate (see Fig. 4) to prevent thermal runaway and maintain a uniform temperature.

[0028] As is known in the art, unlike thermocouples and other temperature sensors, which measure a current temperature state as a discrete temperature and tend to respond slowly and with high overshoot, flow sensors are typically fast and high-resolution and can therefore quickly detect phase transitions in the battery cell 12 during charging and discharging. Therefore, while temperature measurement continues to be useful in battery monitoring and control, the additional flow measurement can improve knowledge of the static and dynamic temperature conditions of the battery cell 12.

[0029] In one possible embodiment, the optional heat flow sensors 650 can be Fig. 1B as series-connected semiconductor stacks configured to detect convection, conduction, and radiation heat flows. As is known in the art, a temperature gradient between dissimilar electrically conductive materials generates a voltage difference according to the Seebeck effect, wherein the voltage difference is proportional to the amount of heat dissipated by a surface, in this case, the cell surface 12A or 12B of the battery cell 12 ( Fig. 1A), flows. The optional arrangement 65 of heat flow sensors 650 in Fig. 1B is thus usable as part of the battery electric device 10 of the present invention, with other possible embodiments being characterized by the absence of the heat flow sensors 650.

[0030] Fig. 1C, for its part, shows a representative embodiment of the second TEA 240 in a side cross-sectional view, in which the TEMs 16 are optionally embedded in a thermally conductive foam 19 between the heat sink 18 and the metal plate 22. The thicknesses of the TEMs 16 and the foam 19 are not to scale but are exaggerated for illustrative purposes. This use of foam 19 can help secure, cushion, and hold the TEMs 16 in an optimal location adjacent to the heat sink 18. In one possible embodiment, the heat sink 18 can include a plurality of cooling fins 18F separated by air gaps 17, as shown, allowing for good airflow and heat dissipation from the battery cell 12.

[0031] With brief reference to Fig. 2A and Fig. 2B there are various solutions for the implementation of the pressure regulator 15 from Fig. 1A, when constant pressure (arrows PP) is applied to the cell surfaces 12A and 12B and heat is pumped to or from the battery cell 12. As in Fig. 2A, for example, in this case, the first TEA 140 and its heat sink 18 could slide up and down on rods, one of which is shown as rod 40, via through-holes 41 drilled into the first TEA 140 and the heat sink 18. Such an implementation would align the first and second TEAs 140 and 240 and their respective heat sinks 18, thus minimizing sideways movement. The first TEA 140 and the associated heat sink 18 can move freely up and down on the aforementioned rods 40, and the constant pressure (arrows PP) could then be applied in various ways. The constant pressure (arrows PP), which may vary depending on the application, is about 25 kPa to about 35 kPa in one non-limiting embodiment.

[0032] As a non-limiting example, a spring 42 according to Fig. 2A on the above-mentioned rod 40 above the first TEA 140 / first heat sink 18 with sufficient displacement so that the spring 42 does not change noticeably upon expansion and contraction of the battery cell 12. A nut 44 can be attached to the upper end of the rod 40, as shown, so that the spring 42 is located between the nut 44 and the first TEA 140 / heat sink 18. The constant force (arrow PP) can be applied by tightening the nut 44 on each rod 40, i.e., by a torque (arrow T 40 ), which is applied around an axis 11 of the rod 40. In one embodiment, the plates 22 may be made of Fig. 1A parallel to the battery cell 12 can be slightly extended to allow connections via the rods 40, the rods 40 and the nuts 44 in Fig. 2A practically act as pressure control screws.

[0033] Alternatively, as in Fig. 2B, instead, with a similar effect, place a calibrated mass 45 on the first TEA 140 / heat sink 18, whereby Fig. 2B assumes that the first TEA 140 is located directly above the second TEA 240. In such an embodiment, the mass 45 is arranged such that its thickness direction is perpendicular to the direction of gravity (arrow G). Other solutions not specifically shown in the figures are conceivable within the scope of the invention, including attaching a computer-controlled hydraulic or electric press and controlling it to raise and lower the first TEA 140 and the heat sink 18, possibly based on feedback from a pressure regulator.

[0034] According to Fig. 3, the heat flow sensors 650 can be Fig. 2B, as shown, be spaced apart from each other, wherein in the non-limiting embodiment, nine heat flow sensors 650 are used. Each of the heat flow sensors 650 rests on a specific part of the metal plate 22 and is surrounded by a corresponding window 230 formed in the thermal pad 23. The flexible graphite plate 25 of Fig. 1B, which for clarity is shown in Fig. 3 was omitted, but in Fig. 4, is arranged above the heat flow sensors 650. The values ​​measured by the individual heat flow sensors 650 can be transmitted via corresponding output voltage lines 46 to the processor 51 of Fig. 8. Each heat flow sensor 650, or a thermocouple in an alternative embodiment, may also transmit a discrete temperature signal via one or more of the output voltage lines 48.

[0035] The particular arrangement of the heat flux sensors 650 and the relative positions of the output voltage lines 46 within a particular window 280 of the thermal pad 23 may vary depending on the application. As shown in Fig. 3 and Fig. 4 for a particular heat flow sensor 650, the heat flow sensor 650 can be arranged within a corresponding window 230 next to the metal plate 22 and finally covered by the graphite plate 25, as in Fig. 4, which for the sake of clarity shows a heat flow sensor 650 and a corresponding window 230 from Fig. 3 illustrates.

[0036] The particular arrangement of the TEAs 140 and 240 on a particular battery cell 12 may vary depending on the application and structure or profile of the battery cell 12, wherein the battery electric device 10 may be Fig. 1A with such an arrangement may be characterized by the absence of the heat flow sensors 650, as mentioned above. The TEAs 140 and 240 help determine the heat generation of the battery cell 12 by pumping out a certain amount of heat, typically to set a temperature setpoint. For example, if the battery cell 12 is set to 25°C as the above-mentioned temperature setpoint, the heat generated at 25°C—a temperature maintained, as is common in the prior art, by a separate regulator—could be calculated using the electrical signal output via the output voltage lines 48 from Fig. 3, such electrical signal being indicative of the heat pumped to the battery cell 12 to maintain the temperature setpoint of 25°C in this representative example.

[0037] With brief reference to Fig. 5 and Fig. 6 could be used instead of the Fig. 1A-1C, TEAs 340 or other heat pumps of different sizes on different areas of the cell surface 12A and 12B of the Fig. 1A. More or smaller TEAs 340 may be used in a smaller area, for example, to provide more accurate or detailed data, such as in areas more susceptible to harmful thermal effects. Interior areas of the battery cell 12 or areas requiring less detailed or precise data may be equipped with fewer TEAs, as illustrated by TEA 4. In the non-limiting arrangement according to Fig. 5, TEA 4 is flanked by two smaller TEAs 340, i.e., TEA 3 and TEA 5, which in turn are adjacent to even smaller TEAs 340, in this example referred to as TEA 1 and TEA 2 (next to TEA 3) and TEA 6 and TEA 7 (next to TEA 5). The present teachings therefore provide for the use of only one TEA 340 per battery cell 12 up to several TEAs 340 per battery cell 12, wherein in the non-limiting embodiment according to Fig. 5 seven TEAs 340 are used for a specific main area of ​​the battery cell 12.

[0038] In contrast, in Fig. 6 shows a schematic side view of the use of eight equal-sized TEAs 340 per main cell area 12A and 12B of the battery cell 12. In one embodiment, the constant pressure (arrows PP) can be Fig. 2A and Fig. 2B may be about 25 kPA to about 35 kPA. Each TEM 16 of the TEAs 340 may correspond to a surface profile of the battery cell 12. This may be independent of the shape or outer profile of the battery cell 12, wherein the Fig. 1A-6 and typical for pouch cells are generally flat.

[0039] With reference now to Fig. 7, a battery electric device 100 may include a cylindrical embodiment of the battery cell 12, such an embodiment being referred to as a cylindrical battery cell 120. The plurality of TEAs, in this case, includes a pair of interdigitated TEAs 440 sandwiching the cylindrical battery cell 120. In the representative embodiment shown, the cylindrical battery cell 120 is connected to a single heat flux sensor 650. In other embodiments, additional heat flux sensors 650 may be employed. Each TEA 440 includes a corresponding fan 20 and heat sink 180, as in the previously described embodiments.

[0040] The heat sinks 180, in this case, may be molded in a generally U-shaped arrangement, as shown, with the heat sinks 180 having a flat bottom 58. As part of the illustrated construction, the TEA 440 includes a battery housing 60 having a flat surface 61, longitudinally extending sidewalls 62, and a hemispherical inner surface 63 connecting the sidewalls 62. In this embodiment, the TEM 16 may be enclosed between the flat bottom 58 of the heat sink 180 and the flat surface 61 of the housing 60. The sidewalls 62 of the TEAs 440 may define a locking mechanism, e.g., a mating clamp 64 and 164, which cooperate to securely grip a periphery of the cylindrical battery cell 120. The resulting gripper-like engagement thus serves to enclose the cylindrical battery cell 120.For clarity, the heat flux sensor 650, the size, number and distribution of which may depend on the application or intended use, is shown in . Fig. 7 is shown exaggeratedly large and, in some embodiments, may be curved and / or reduced in size to fit a circumferential cell surface 12C of the battery cell 120.

[0041] With reference now to Fig. Figure 8 illustrates the battery system 50 according to an exemplary hardware configuration, in which an external process controller 70 is connected to the processor 51 of a battery control module 55. The external process controller 70 is configured to execute a control process with respect to the battery cell 12 and / or the electrical load 52 in response to the measured heat quantity, e.g., by transmitting an electronic control signal (arrow CC). O) to a controlled downstream device 82. The controlled downstream device 82 may include, for example and without limitation, a cooling system for a main battery pack including the battery cell 12, an indicator device configured to display, in response to the electronic control signal (arrow CC O ) to light up, or comprise a motor control processor for a rotating electric machine (not shown) that is connected to the battery cell 12, e.g. as an electrical load 52. In the exemplary construction, the battery cell 12 is connected via a switching device 57 to a main power supply 56 and the electrical load 52, wherein the state of the main power supply 56 and the electrical load 52 is ultimately determined via the processor 51 via corresponding power supply and electrical load control signals (arrow CC 56 or CC 52). The electrical load 52 enables the discharge of the battery cell 12 and dissipates the discharged energy, e.g., through resistance heating, or the electrical load 52 can divert the energy to other applications. The main power supply 56, in turn, charges the battery cell 12 by applying a power and an electrical potential that is greater than the current cell voltage.

[0042] The information supplied to the processor 51 during operation of the battery system 50 from Fig. 8 may include a measured current and / or voltage signal 71, a measured temperature signal 72 and the measured heat flow signal 73. As is known in the art, the heat flow corresponds to the heat transfer rate per unit area and can be expressed as Q˙A where Q̇ is the heat transfer rate in British Thermal Units (BTU) per hour and A is the corresponding surface area in ft 2 In addition, a bipolar power supply 75 supplies a temperature control signal 77 to the battery-electric device 10 to cause the fans 20 to maintain a constant set temperature when the battery-electric device 10 and in particular the battery cell 12 contained therein is pressurized by the pressure control system 15 from Fig. 1A is kept under constant pressure as described above.

[0043] In view of the above invention, one skilled in the art will recognize that the described battery-powered device 10 and its alternative embodiments allow for various approaches. For example, a method for constructing the battery-powered device 10 for use with the electrical load 52 of Fig. 2 the arrangement of a plurality of heat flow sensors 650 from Fig. 1B on a cell surface 12A and / or 12B of the electrochemical battery cell 12. Such a method also includes providing a pair of direct air TEAs, e.g., the one shown in Fig. 1A, with one or more TEMs 16 ( Fig. 1C), which are arranged between the heat sink 18 and the metal plate 22.

[0044] Within the scope of this exemplary method, the battery cell 12 and the heat flux sensors 650 disposed thereon may be positioned between the metal plate 22 of each pair of direct air TEAs 140 and 240. The pressure control device 15 is then used to exert a constant pressure on the cell surfaces 12A and 12B, i.e., by uniformly compressing the battery cell 12 when the battery cell 12 is connected to the electrical load 52, while the TEAs 140 and 240 are actively pumping an amount of heat to or from the battery cell. Such a method may include transmitting an output voltage signal 72 and / or 73 indicative of the amount of heat to the processor 51. Fig. 8 via the plurality of heat flow sensors 650. Embodiments of this method may also include determining the amount of heat pumped by the battery cell 12 at a calibrated temperature setpoint via the processor 51 based on the output voltage signal 72 and / or 73, the amount of heat in this case being the heat flow. The processor 51 then controls the operation of the battery-electric device 10 to maintain the temperature setpoint. Other parameters, possibly determined by the controller 70, may include: Fig. 8 may include instructing a change in the energy flow of the battery cell 12 or instructing a thermal regulation thereof, these operations occurring in response to the amount of heat.

[0045] As one skilled in the art will appreciate, a battery cell generally generates heat (exothermic) during operation because ohmic resistances predominate compared to other heat source terms. However, in certain application cases, the battery cell's heat generation may be negative (endothermic). This is because the reversible heat (entropic source) actually shifts negative and dominates the ohmic heat source term. Thus, although various examples described herein measure the heat flow flowing from the battery cell to the ambient, there are one or more specific application cases where heat flows from the ambient to the battery cell during isothermal operation. One skilled in the art will appreciate that the present teachings can be extended to exothermic or endothermic processes in the various battery cells 12 described herein.

[0046] The various hardware solutions and methods described herein enable accurate and domain-specific assessment of uneven heat generation in an electrochemical battery cell or in larger batteries constructed from multiple such cells, using targeted arrays of direct air-source heat pumps, in which the battery cell is sandwiched between opposing heat pumps, depicted here as solid-state thermoelectric assemblies. The disclosed solutions can be implemented for use with pouch and prismatic battery cells, with structural modifications to the heat pump enabling profile-appropriate integration with cylindrical battery cells.The use of such heat pumps, combined with the constant pressure applied during a heat pumping process, provides an overall more reliable approach to cell-level thermal evaluation in the battery cell, as well as in battery systems utilizing the battery cell. In light of the above invention, those skilled in the art will readily appreciate these and other related advantages.

Claims

[1] Battery-powered electrical device (10) for use with an electrical load (52), comprising: an electrochemical battery cell (12) connectable to the electrical load (52) and having a cell surface (12A, 12B); a direct air heat pump (14) in thermal communication with the cell surface (12A, 12B); a pressure control device (15) designed to exert a constant pressure on the cell surface (12A, 12B) when the battery cell (12) is connected to the electrical load (52), wherein the connection of the battery cell (12) to the electrical load (52) causes the direct air heat pump (14) to pump out an amount of heat from the battery cell (12); and at least one sensor configured to generate an output voltage signal indicative of the amount of heat; characterized by , that the heat pump (14) comprises a thermoelectric assembly (TEA) (140, 240) with a solid-state thermoelectric module (TEM) (16), a heat sink (18) and a fan (20) for cooling the TEM (16) in response to a temperature control signal; wherein the battery cell (12) is a pouch cell or a prismatic cell, and wherein the TEA (140, 240) comprises a distributed array of TEAs (140, 240), each individual TEA (140, 240) of the distributed array of TEAs (140, 240) being positioned on a corresponding surface portion of the battery cell (12); and where: (i) the at least one sensor comprises an array of heat flow sensors (650), wherein each individual heat flow sensor of the array of heat flow sensors (650) is distributed on the cell surface (12A, 12B) and is designed to measure the local heat flow at a corresponding portion of the cell surface (12A, 12B); and / or (ii) the heat pump (14) comprises a plurality of heat pumps (14), each of which corresponds to a surface profile of the battery cell (12), wherein the battery cell (12) is a cylindrical battery cell (12) and the plurality of heat pumps (14) comprises a pair of engageable thermoelectric assemblies (TEAs) (140, 240) which together sandwich the battery cell (12). [2] The battery electric device (10) of claim 1, further comprising a processor in communication with the at least one sensor, the processor being configured to determine the amount of heat pumped by the battery cell (12) at a calibrated temperature setpoint based on the output voltage signal and thereafter to control operation of the battery electric device (10) to maintain the temperature setpoint. [3] The battery electric device (10) of claim 1, wherein each of the TEAs (140, 240) comprises a hemispherical battery case, a solid-state thermoelectric module (TEM) (16), and a heat sink (18), and the TEM (16) of each corresponding TEA (140, 240) is disposed between the respective hemispherical battery case and the respective heat sink (18). [4] Battery-powered electrical device (10) for use with an electrical load (52), comprising: an electrochemical battery cell (12) connectable to the electrical load (52) and having a cell surface (12A, 12B); a direct air heat pump (14) in thermal communication with the cell surface (12A, 12B); a pressure control device (15) designed to exert a constant pressure on the cell surface (12A, 12B) when the battery cell (12) is connected to the electrical load (52), wherein the connection of the battery cell (12) to the electrical load (52) causes the direct air heat pump (14) to pump out an amount of heat from the battery cell (12); and at least one sensor configured to generate an output voltage signal indicative of the amount of heat; characterized by , that the heat pump (14) defines a through hole in which a corresponding rod (40) is arranged, and wherein the pressure control device (15) comprises the corresponding rod (40) and either a nut (44) or a calibrated mass (45) for applying the constant pressure.

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