Patent Publication Number: US-2017352932-A1

Title: Magnetically Controlled Traction Battery Thermal Plate

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a division of U.S. application Ser. No. 14/538,388 filed Nov. 11, 2014, now U.S. Pat. No. ______, the disclosure of which is hereby incorporated in its entirety by reference herein. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to thermal management systems for high voltage batteries utilized in vehicles. 
     BACKGROUND 
     Vehicles such as battery-electric vehicles (BEVs), plug-in hybrid-electric vehicles (PHEVs), mild hybrid-electric vehicles (MHEVs), or full hybrid-electric vehicles (FHEVs) contain an energy storage device, such as a high voltage (HV) battery, to act as a propulsion source for the vehicle. The HV battery may include components and systems to assist in managing vehicle performance and operations. The HV battery may include one or more arrays of battery cells interconnected electrically between battery cell terminals and interconnector busbars. The HV battery and surrounding environment may include a thermal management system to assist in managing temperature of the HV battery components, systems, and individual battery cells. 
     SUMMARY 
     A vehicle traction battery assembly includes an array of battery cells, a thermal plate, and a magnetic valve assembly. The thermal plate is in thermal communication with the array and defines a flow field therein. The magnetic valve assembly selectively outputs a magnetic field to tune a viscosity of magnetic coolant within a vicinity of the magnetic field and flowing within the flow field to promote or inhibit the flowing within the flow field. The flow field may include first and second channels and the magnetic valve assembly may selectively output the magnetic field to tune the viscosity such that the magnetic coolant flows through the second channel and not the first channel. The thermal plate may define a plurality of valve zones. The magnetic valve assembly may include an electromagnet positioned proximate to each of the valve zones and the magnetic valve assembly may operate the electromagnet to selectively control the flowing of magnetic coolant within each of the valve zones. The magnetic valve assembly may selectively output the magnetic field based on a temperature of the battery cells. The magnetic valve assembly may selectively output the magnetic field to promote the flowing within portions of the flow field adjacent to the battery cells having a temperature exceeding a threshold value. The magnetic coolant may be a magnetorheological fluid or ferrofluid. 
     A vehicle includes an array of battery cells, a thermal plate, coolant, and an electromagnetic valve assembly. The thermal plate is in thermal communication with the array and defines a flow field. The coolant is distributed within the flow field and has magnetic particles therein. The electromagnetic valve assembly is arranged proximate to and outside of the flow field to selectively output a magnetic field to influence configurations of the particles to alter a flow of the coolant through the flow field. The electromagnetic valve assembly may include at least one electromagnet. The electromagnetic valve assembly may vary the output of the magnetic field such that the particles gather in a central region of the flow field or at walls defining the flow field. The flow field may include a plurality of multi-pass channels and the electromagnetic valve assembly may selectively output the magnetic field to direct the flow of the coolant within some of the multi-pass channels. The vehicle may include a controller to, in response to temperature data for the battery cells, control operation of the electromagnetic valve assembly. The coolant may be magnetorheological fluid or ferrofluid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustrating a battery electric vehicle. 
         FIG. 2  is a perspective view of an example of a portion of a traction battery. 
         FIG. 3  is a plan view of an example of a thermal plate having coolant within a flow field. 
         FIG. 4  is a plan view of the thermal plate from  FIG. 3  showing an example of an output of an electromagnetic valve assembly. 
         FIG. 5  is a plan view of another example of a thermal plate showing another example of an output of an electromagnetic valve assembly. 
         FIG. 6  is a plan view of the thermal plate from  FIG. 5  showing another example of an output of an electromagnetic valve assembly. 
         FIG. 7  is a plan view of another example of a thermal plate showing another example of an output of an electromagnetic valve assembly. 
         FIG. 8  is a plan view of the thermal plate and electromagnetic valve assembly from  FIG. 7  showing an example of battery cell locations. 
         FIG. 9  is a perspective view of a portion of a traction battery showing examples of a thermal plate, an array of battery cells, and electromagnets of an electromagnetic valve assembly. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ embodiments of the present disclosure. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations. 
       FIG. 1  depicts a schematic of a typical plug-in hybrid-electric vehicle (PHEV). A typical plug-in hybrid-electric vehicle  12  may comprise one or more electric machines  14  mechanically connected to a hybrid transmission  16 . The electric machines  14  may be capable of operating as a motor or a generator. In addition, the hybrid transmission  16  is mechanically connected to an engine  18 . The hybrid transmission  16  is also mechanically connected to a drive shaft  20  that is mechanically connected to the wheels  22 . The electric machines  14  can provide propulsion and deceleration capability when the engine  18  is turned on or off. The electric machines  14  also act as generators and can provide fuel economy benefits by recovering energy that would normally be lost as heat in the friction braking system. The electric machines  14  may also provide reduced pollutant emissions since the hybrid-electric vehicle  12  may be operated in electric mode or hybrid mode under certain conditions to reduce overall fuel consumption of the vehicle  12 . 
     A traction battery or battery pack  24  stores and provides energy that can be used by the electric machines  14 . The traction battery  24  typically provides a high voltage DC output from one or more battery cell arrays, sometimes referred to as battery cell stacks, within the traction battery  24 . The high voltage DC output may also be converted to a low voltage DC output for applications such as vehicle stop/start. The battery cell arrays may include one or more battery cells. The traction battery  24  is electrically connected to one or more power electronics modules  26  through one or more contactors (not shown). The one or more contactors isolate the traction battery  24  from other components when opened and connect the traction battery  24  to other components when closed. The power electronics module  26  is also electrically connected to the electric machines  14  and provides the ability to bi-directionally transfer electrical energy between the traction battery  24  and the electric machines  14 . For example, a typical traction battery  24  may provide a DC voltage while the electric machines  14  may require a three-phase AC voltage to function. The power electronics module  26  may convert the DC voltage to a three-phase AC voltage as required by the electric machines  14 . In a regenerative mode, the power electronics module  26  may convert the three-phase AC voltage from the electric machines  14  acting as generators to the DC voltage required by the traction battery  24 . The description herein is equally applicable to a pure electric vehicle. For a pure electric vehicle, the hybrid transmission  16  may be a gear box connected to an electric machine  14  and the engine  18  may not be present. 
     In addition to providing energy for propulsion, the traction battery  24  may provide energy for other vehicle electrical systems. A typical system may include a DC/DC converter module  28  that converts the high voltage DC output of the traction battery  24  to a low voltage DC supply that is compatible with other vehicle loads. Other high-voltage loads, such as compressors and electric heaters, may be connected directly to the high-voltage without the use of a DC/DC converter module  28 . In a typical vehicle, the low-voltage systems are electrically connected to an auxiliary battery  30  (e.g., 12V battery). 
     A battery electrical control module (BECM)  33  may be in communication with the traction battery  24 . The BECM  33  may act as a controller for the traction battery  24  and may also include an electronic monitoring system that manages temperature and charge state of each of the battery cells. The traction battery  24  may have a temperature sensor  31  such as a thermistor or other temperature gauge. The temperature sensor  31  may be in communication with the BECM  33  to provide temperature data regarding the traction battery  24 . The temperature sensor  31  may also be located on or near the battery cells within the traction battery  24 . It is also contemplated that more than one temperature sensor  31  may be used to monitor temperature of the battery cells. 
     The vehicle  12  may be, for example, an electric vehicle such as a PHEV, a FHEV, a MHEV, or a BEV in which the traction battery  24  may be recharged by an external power source  36 . The external power source  36  may be a connection to an electrical outlet. The external power source  36  may be electrically connected to electric vehicle supply equipment (EVSE)  38 . The EVSE  38  may provide circuitry and controls to regulate and manage the transfer of electrical energy between the power source  36  and the vehicle  12 . The external power source  36  may provide DC or AC electric power to the EVSE  38 . The EVSE  38  may have a charge connector  40  for plugging into a charge port  34  of the vehicle  12 . The charge port  34  may be any type of port configured to transfer power from the EVSE  38  to the vehicle  12 . The charge port  34  may be electrically connected to a charger or on-board power conversion module  32 . The power conversion module  32  may condition the power supplied from the EVSE  38  to provide the proper voltage and current levels to the traction battery  24 . The power conversion module  32  may interface with the EVSE  38  to coordinate the delivery of power to the vehicle  12 . The EVSE connector  40  may have pins that mate with corresponding recesses of the charge port  34 . 
     The various components discussed may have one or more associated controllers to control and monitor the operation of the components. The controllers may communicate via a serial bus (e.g., Controller Area Network (CAN)) or via discrete conductors. 
     The battery cells, such as a prismatic cell, may include electrochemical cells that convert stored chemical energy to electrical energy. Prismatic cells may include a housing, a positive electrode (cathode) and a negative electrode (anode). An electrolyte may allow ions to move between the anode and cathode during discharge, and then return during recharge. Terminals may allow current to flow out of the cell for use by the vehicle. When positioned in an array with multiple battery cells, the terminals of each battery cell may be aligned with opposing terminals (positive and negative) adjacent to one another and a busbar may assist in facilitating a series connection between the multiple battery cells. The battery cells may also be arranged in parallel such that similar terminals (positive and positive or negative and negative) are adjacent to one another. For example, two battery cells may be arranged with positive terminals adjacent to one another, and the next two cells may be arranged with negative terminals adjacent to one another. In this example, the busbar may contact terminals of all four cells. The traction battery  24  may be heated and/or cooled using a liquid thermal management system, an air thermal management system, or other method as known in the art. 
     The traction battery  24  may be heated and/or cooled using a liquid thermal management system, an air thermal management system, or other method as known in the art. In one example of a liquid thermal management system and now referring to  FIG. 2 , the traction battery  24  may include a battery cell array  88  shown supported by a thermal plate  90  to be heated and/or cooled by a thermal management system. The battery cell array  88  may include a plurality of battery cells  92  positioned adjacent to one another and structural components. The DC/DC converter module  28  and/or the BECM  33  may also require cooling and/or heating under certain operating conditions. A thermal plate  91  may support the DC/DC converter module  28  and BECM  33  and assist in thermal management thereof. For example, the DC/DC converter module  28  may generate heat during voltage conversion which may need to be dissipated. Alternatively, thermal plates  90  and  91  may be in fluid communication with one another to share a common fluid inlet port and common outlet port. 
     In one example, the battery cell array  88  may be mounted to the thermal plate  90  such that only one surface, of each of the battery cells  92 , such as a bottom surface, is in contact with the thermal plate  90 . The thermal plate  90  and individual battery cells  92  may transfer heat between one another to assist in managing the thermal conditioning of the battery cells  92  within the battery cell array  88  during vehicle operations. Uniform thermal fluid distribution and high heat transfer capability are two thermal plate  90  considerations for providing effective thermal management of the battery cells  92  within the battery cell arrays  88  and other surrounding components. Since heat transfers between thermal plate  90  and thermal fluid via conduction and convection, the surface area in a thermal fluid flow field is important for effective heat transfer, both for removing heat and for heating the battery cells  92  at cold temperatures. For example, charging and discharging the battery cells generates heat which may negatively impact performance and life of the battery cell array  88  if not removed. Alternatively, the thermal plate  90  may also provide heat to the battery cell array  88  when subjected to cold temperatures. 
     The thermal plate  90  may include one or more channels  93  and/or a cavity to distribute thermal fluid through the thermal plate  90 . For example, the thermal plate  90  may include an inlet port  94  and an outlet port  96  that may be in communication with the channels  93  for providing and circulating the thermal fluid. Positioning of the inlet port  94  and outlet port  96  relative to the battery cell arrays  88  may vary. For example and as shown in  FIG. 2 , the inlet port  94  and outlet port  96  may be centrally positioned relative to the battery cell arrays  88 . The inlet port  94  and outlet port  96  may also be positioned to the side of the battery cell arrays  88 . Alternatively, the thermal plate  90  may define a cavity (not shown) in communication with the inlet port  94  and outlet port  96  for providing and circulating the thermal fluid. The thermal plate  91  may include an inlet port  95  and an outlet port  97  to deliver and remove thermal fluid. Optionally, a sheet of thermal interface material (not shown) may be applied to the thermal plate  90  and/or  91  below the battery cell array  88  and/or the DC/DC converter module  28  and BECM  33 , respectively. The sheet of thermal interface material may enhance heat transfer between the battery cell array  88  and the thermal plate  90  by filling, for example, voids and/or air gaps between the battery cells  92  and the thermal plate  90 . The thermal interface material may also provide electrical insulation between the battery cell array  88  and the thermal plate  90 . A battery tray  98  may support the thermal plate  90 , the thermal plate  91 , the battery cell array  88 , and other components. The battery tray  98  may include one or more recesses to receive thermal plates. 
     Different battery pack configurations may be available to address individual vehicle variables including packaging constraints and power requirements. The battery cell array  88  may be contained within a cover or housing (not shown) to protect and enclose the battery cell array  88  and other surrounding components, such as the DC/DC converter module  28  and the BECM  33 . The battery cell array  88  may be positioned at several different locations including below a front seat, below a rear seat, or behind the rear seat of the vehicle, for example. However, it is contemplated the battery cell arrays  88  may be positioned at any suitable location in the vehicle  12 . 
     As described above, electrified vehicles utilize HV battery systems. The HV battery systems benefit from uniform temperature conditions of the battery cells within the HV battery system. Coolant is typically pumped through a closed loop path in liquid cooled HV battery systems. The coolant may accumulate heat from the battery cells and other components as the coolant flows through the closed loop path. Battery cells of the HV battery system may age differently due to varying temperatures of the battery cells during operation of the electrified vehicle. This varied aging between the battery cells may result in performance degradation of the HV battery system and the electrified vehicle. Thermal plates which assist in cooling the battery cells may often include channel configurations to distribute the coolant throughout the thermal plate to manage thermal conditions of the battery cells. The thermal plates may be formed in various fashions, but costs to produce the thermal plates may increase due to complexities of the channel configurations. 
       FIG. 3  shows an example of a portion of a thermal management system for an HV battery system which may use a magnetic valve assembly to control a flow of coolant having magnetic particles. A thermal plate  100  may include a first wall  104  and a second wall  106 . An inlet  108  may deliver coolant  109  to a flow field defined by the first wall  104  and the second wall  106 . An outlet  110  may remove coolant from the flow field. A magnetic valve assembly may assist in controlling coolant flow within the thermal plate  100 . For example, the coolant  109  may include magnetic particles  114  that may be magnetically optimizable. Magnetorheological (MR) fluid and ferrofluid are two examples of magnetically optimizable liquids which may be used for the coolant  109 . When MR fluid or ferrofluid is exposed to a magnetic field, a viscosity of the fluid may be tuned to selectively inhibit or promote flow. For example, the magnetic field may influence a position or movement of the magnetic particles. Various ratios of magnetic particles and fluid are available to provide multiple options for a composition of the coolant  109 . A size and type of the magnetic particle are two factors which may influence selection of the composition of the coolant  109 . 
     In  FIG. 3 , the coolant  109  is shown with the magnetic particles  114  in a normal or random configuration. For example, in the case of MR fluids, distribution of the magnetic particles  114  is driven by coolant  109  flow, whereas in the case of ferrofluids, distribution of the magnetic particles  114  is driven by Brownian motion. Magnetic particles in both MR fluids and ferrofluids experience a magnetic force parallel to the line of magnetic flux created by an electromagnet. The applied magnetic field is anisotropic, with regions of greater and lesser magnetic flux due to magnetic pole location. The magnetic particles  114  may be oriented in specific configurations to promote or inhibit coolant  109  flow by selectively placing single or multiple electromagnets adjacent to the coolant  109 . The electromagnets may also be configured to pulse the output of the magnetic field such that the coolant  109  reaches an intermediate condition in which laminar coolant  109  flow is induced to become more turbulent to increase heat transfer properties of the coolant  109 . 
       FIG. 4  shows an example in which the magnetic particles  114  are reconfigured due to output of a magnetic field  118  generated by electromagnets  120 . The electromagnets  120  may be placed adjacent the flow field of the thermal plate  100  to selectively control flow of the coolant  109  by exerting a force against the magnetic particles  114 . In this example, the electromagnet  120  is activated to output the magnetic field  118  as represented by directional arrows. The magnetic field  118  exerts the force on the magnetic particles  114  such that a positioning of the magnetic particles  114  may be reconfigured. In this example, the magnetic particles  114  are shown realigned in a substantially liner configuration in comparison with the normal or random configuration shown in  FIG. 3 . In  FIG. 4 , the four electromagnets  120  are shown to create four columns of the magnetic particles  114  being driven toward the wall  104  by the magnetic force of the magnetic field  118 . The applied magnetic force in this example is perpendicular to the direction of coolant  109  flow and by causing motion of the magnetic particles  114  into the wall  104  it is possible to increase the local viscosity of the coolant  109  and to increase a contribution of wall shear stress to retard the coolant  109  flow. 
       FIG. 5  shows another example in which the magnetic particles  114  are reconfigured due to output of a magnetic field  122  by an electromagnet  124  which may be located below the thermal plate  150 . In this example, the output of the magnetic field  122  travels from below the thermal plate  150  (as represented by a series of directional Xs) and influences the magnetic particles  114  to reconfigure and collect at the wall  104  and the wall  106 . Flow of the coolant  109  may be influenced to travel along a central portion of the flow field defined by the thermal plate  100 .  FIG. 6  shows another example in which the magnetic particles  114  are reconfigured due to output of magnetic fields  128  by electromagnets  130  and electromagnets  132 . In this example, the output of the magnetic fields  128  influences the magnetic particles  114  to reconfigure and collect in the central portion of the flow field. Flow of the coolant  109  may be influenced to travel along outer portions of the flow field defined by the thermal plate  100 . The locations of the electromagnets  130  and the electromagnets  132  in this example create two sub-coolant paths  136  and  138  of the flow field. 
       FIGS. 7 and 8  show an example of another thermal plate  150  which may utilize a magnetic valve assembly to control a flow of coolant having magnetic particles therein. The thermal plate  150  may include an inlet  154  and an outlet  156 . A plurality of battery cells may be supported by the thermal plate  150  and/or in thermal communication therewith. A flow field for coolant is included between the inlet  154  and the outlet  156 . For example, the thermal plate  150  may include a wall  160  to define the flow field therebetween. In other examples, the thermal plate  150  may define one or more extrusions within the flow field to distribute the coolant throughout the thermal plate  150 . Battery cells  164  and  166  are shown spaced apart in one example of a battery cell configuration. 
     A magnetic valve assembly may assist in controlling the flow of coolant within the thermal plate  150 . For example, the magnetic valve assembly may include one or more electromagnets as shown in  FIG. 8 . A first valve zone  170  may correspond to a first electromagnet  180 . A second valve zone  172  may correspond to a second electromagnet  184 . A third valve zone  174  may correspond to a third electromagnet  186 . The valve zones are shown with directional arrows to represent an example of a direction of magnetic fields output by the electromagnets. A control system may direct operation of the magnetic valve assembly based on operating conditions of the battery cells. For example, a controller (not shown) may direct operation of the first electromagnet  180 , the second electromagnet  184 , and the third electromagnet  186 . One or more sensors (not shown) may be located proximate to or integrated with the battery cells  164  and  166 . The one or more sensors may measure temperature conditions of the battery cells. The one or more sensors may be in communication with the controller and configured to send one or more signals thereto. For example, the one or more sensors may include the measured temperature conditions in the one or more signals sent to the controller. The controller may be configured to, in response to receiving the one or more signals from the one or more sensors including the measured temperature of the battery cells, direct one or more of the electromagnets to adjust an output of a magnetic field such that the coolant flow is altered based on the measured temperature of the battery cells. 
     For example, the controller may receive a signal from one of the sensors indicating that battery cells proximate the first electromagnet  180  are operating at a temperature above a predetermined threshold. The predetermined threshold may be, for example, a battery cell temperature at which the battery cell may decrease in performance. The controller may direct the second electromagnet  184  and the third electromagnet  186  to output a magnetic field such that coolant is prohibited or limited from flowing through the second valve zone  172  and the third valve zone  174 . As such, coolant may be directed toward the battery cells which are operating at a temperature above the predetermined threshold to assist in cooling the battery cells. In another example, the controller may receive a signal from one of the sensors indicating that battery cells proximate the second electromagnet  184  are operating at a temperature above the predetermined threshold. The controller may direct the first electromagnet  180  and the third electromagnet  186  to output a magnetic field such that coolant is prohibited or limited from flowing through the first valve zone  170  and the third valve zone  174 . This magnetic valve assembly configuration provides a capability to control coolant flow within the thermal plate and without utilizing mechanical valves or mechanical components within the thermal plate  150 . It is contemplated that other combinations of magnetic field outputs from the first electromagnet  180 , the second electromagnet  184 , and the third electromagnet  186  may alter a flow of the coolant within the thermal plate  150 . Further, more or fewer electromagnets may be utilized to provide additional coolant flow control options. 
       FIG. 9  shows another example of a thermal plate  220  which may utilize a magnetic valve assembly to assist in managing thermal conditions of an array of battery cells  224 . The battery cells  224  may be in thermal communication with the thermal plate  220 . In this example, coolant may enter and exit the thermal plate  220  via a plate inlet  230  and a plate outlet  234 , respectively. The thermal plate  220  may define a plurality of multi-pass channels, such as a first multi-pass channel  226   a,  a second multi-pass channel  226   b,  a third multi-pass channel  226   c,  and a fourth multi-pass channel  226   d  (collectively referred to as “multi-pass channels  226 ” herein). Coolant may flow through the multi-pass channels  226  to assist in managing thermal conditions of the battery cells  224 . One or more electromagnets may be arranged with the multi-pass channels  226  to assist in managing coolant flow within the thermal plate  220 . For example, a first electromagnet  250  may be arranged with the first multi-pass channel  226   a  such that a magnetic field output of the first electromagnet  250  may influence magnetic particles of the coolant flowing toward or within the first multi-pass channel  226   a.  The influence of the magnetic field may be such that the magnetic particles are reconfigured to prohibit, limit, or alter coolant flow as described above. Similarly, a second electromagnet  252 , a third electromagnet  254 , and a fourth electromagnet  256  may influence magnetic particles of the coolant flowing toward or within the respective second multi-pass channel  226   b,  the third multi-pass channel  226   c,  and the fourth multi-pass channel  226   d.  In this example, the electromagnets are located above the battery cells  224 . 
     While various embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the disclosure that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to marketability, appearance, consistency, robustness, customer acceptability, reliability, accuracy, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and can be desirable for particular applications.