System and method for reducing thermal events of battery array

Abstract

The present disclosure provides a system and method for reducing thermal events of a battery array. Systems and methods for reducing the likelihood of deterioration diffusion of battery cells are described. In one example, degradation of a battery cell may be determined via pressure or temperature. If degradation is detected, increasing cooling of the battery cell is postponed to permit emission of gases generated via the battery, such that thermal load and pressure within the battery may be reduced.

Description

Technical Field

[0001] This specification relates to methods and systems for use with batteries. These methods and systems may be particularly useful for batteries that are part of a vehicle and provide charge to propel the vehicle. Background Technology

[0002] A vehicle may include a battery that supplies charge to a motor that propels the vehicle. The battery may consist of multiple battery cells arranged in an array. The array may include battery cells electrically connected in parallel and series. The battery cells may be positioned close to each other to reduce battery size and improve the efficiency of power transfer through the battery. However, if one or more battery cells experience degradation, the close proximity of adjacent battery cells may increase the likelihood of battery degradation. One way to reduce the likelihood of battery degradation is to disconnect the battery from the vehicle's power consumers (e.g., the motor that propels the vehicle). However, if the battery degradation is internal, disconnecting the battery from the vehicle's power consumers may not help reduce the likelihood of additional battery degradation. Summary of the Invention

[0003] This specification relates to a method and system for controlling temperature and degradation within a vehicle battery. Specifically, if the temperature of a particular battery cell exceeds a threshold temperature, coolant can begin flowing to the battery cell after a delay period. By delaying the increase in coolant flow to the battery cell, gases from one battery cell can be vented from the battery casing, reducing the tendency for battery gases to mix with the battery coolant, thereby lowering the pressure within the battery. Gases from degraded battery cells can be vented from the battery casing before increased cooling of the battery, allowing a greater amount of heat to be released from the battery before heat from the vented battery cell is transferred to the battery coolant. Therefore, the pressure and temperature within the battery can be reduced, resulting in less heat transfer to adjacent battery cells. Furthermore, the battery coolant can provide greater cooling capacity to adjacent battery cells, thereby reducing the likelihood of degradation in adjacent battery cells. Attached Figure Description

[0004] The advantages described herein will be more fully understood when read, either alone or with reference to the accompanying drawings, by reading examples of embodiments referred to herein as specific implementations, in which:

[0005] Figure 1 This is a schematic diagram of an example electric vehicle and its charger;

[0006] Figure 2 This is a perspective view of an example battery test configuration;

[0007] Figure 3 The graph shows the battery operating conditions during the battery testing procedure;

[0008] Figure 4 An example cooling system for the battery is shown;

[0009] Figure 5 An example operation sequence of the first battery control strategy is shown;

[0010] Figure 6 An example operating sequence of the second battery control strategy is shown;

[0011] Figure 7 A flowchart of an example second battery control strategy is shown;

[0012] Figure 8 An example operating sequence of the third battery control strategy is shown; and

[0013] Figure 9 A flowchart of an example third battery control strategy is shown. Detailed Implementation

[0014] Batteries can be included in electric vehicles, such as Figure 1 As shown. The battery can be as follows. Figure 2 The battery can be constructed as shown. Figure 3 Operate as shown. The battery can be cooled via a cooling system, such as... Figure 4 As shown. The battery can be cooled, as... Figure 5 As shown. Figure 6 The alternative battery operation sequence is shown in the diagram. Figure 7 The diagram shows a flowchart of a method for operating the battery. Figure 8 The second battery operation sequence is shown in the figure. Figure 9 The diagram illustrates a second method for operating the battery.

[0015] Unexpected increases in battery temperature can be caused by battery manufacturing issues, cell degradation, and / or cell deformation. For example, the temperature of a battery cell may rise above a threshold temperature in response to cell degradation. This temperature increase in the degraded cell can cause the temperature of adjacent cells to rise, thereby leading to degradation of nearby cells. The battery's output capacity can decrease as the cells within the battery degrade. Therefore, it may be desirable to provide a way to reduce the possibility of further degradation within the battery when cell degradation is detected.

[0016] The inventors of this paper have recognized the above-mentioned problems and have developed a method for a battery, the method comprising: increasing the flow rate of dielectric fluid to the battery via a controller in response to an indication of battery condition exceeding a threshold and after a predetermined threshold time has elapsed since the most recent indication of battery condition exceeding the threshold.

[0017] By delaying the introduction of increased dielectric fluid flow into the battery, mixing of battery gases and dielectric fluid is reduced, thereby lowering the pressure and temperature within the battery. This reduces the likelihood of degradation of additional battery cells within the battery. The time delay between detecting cell degradation and increasing dielectric fluid flow allows a vent valve to open, enabling the removal of gases generated by the degraded cell from the battery. Therefore, it prevents the temperature of other battery cells in the battery from subsequently rising.

[0018] This specification offers several advantages. Specifically, the method reduces the likelihood of cell degradation propagation when the battery cell temperature rises above a threshold temperature. Furthermore, the method can be based on pressure or temperature measurements within the battery, thereby increasing its flexibility. Additionally, the method can constrain pressure buildup within the battery and allows for the removal of the water vapor separator from the battery cooling system, thereby reducing the financial costs of the battery cooling system.

[0019] The above and other advantages and features of this specification will become readily apparent when understood alone or in conjunction with the accompanying drawings, based on the following detailed description.

[0020] It is understood that the above description of the invention is provided to present a series of concepts further described in the detailed embodiments in a simplified form. This is not intended to identify key features of the claimed subject matter, the scope of which is uniquely defined by the claims appended to the detailed embodiments. Furthermore, the claimed subject matter is not limited to solutions to any of the shortcomings mentioned above or in any part of this disclosure.

[0021] Figure 1 This is a schematic diagram of a vehicle 121 including a powertrain or drivetrain 100. The front portion of the vehicle 121 is indicated by 110, and the rear portion of the vehicle 121 is indicated by 111. The drivetrain 100 includes an electric motor 126. The electric motor 126 can consume or generate electricity depending on its operating mode. (Through) Figure 1 Mechanical connections between various components are shown as solid lines, while electrical connections between various components are shown as dashed lines.

[0022] The drivetrain 100 has a rear axle 122. In some examples, the rear axle 122 may include two half-shafts, such as a first half-shaft 122a and a second half-shaft 122b. The drivetrain 100 also includes a front wheel 130 and a rear wheel 131. The rear wheel 131 can be driven via a motor 126.

[0023] The rear axle 122 is connected to the motor 126. The rear drive unit 136 transmits power from the motor 126 to the axle 122, thereby rotating the rear wheels 131. The rear drive unit 136 may include a low gear 175 and a high gear 177 connected to the motor 126 via an output shaft 126o of the motor 126. The low gear 175 may be engaged via a fully engaged low gear clutch 176. The high gear 177 may be engaged via a fully engaged high gear clutch 178. The high gear clutch 178 and the low gear clutch 176 may be disengaged and engaged via commands received by the rear drive unit 136 through network 199. Alternatively, the high gear clutch 178 and the low gear clutch 176 may be disengaged and engaged via a digital output or pulse width provided by the control system 114. The rear drive unit 136 may include a differential gear set 128 such that torque can be supplied to the first half-shaft 122a and the second half-shaft 122b. In some examples, an electronically controlled differential clutch (not shown) may be included in the rear drive unit 136.

[0024] Motor 126 can receive power from on-board energy storage device 132. Additionally, motor 126 can function as a generator to convert the vehicle's kinetic energy into electrical energy, which can be stored in energy storage device 132 for later use by motor 126. Inverter 134 can convert the alternating current generated by motor 126 into direct current for storage in energy storage device 132, and vice versa. Electric drive system 135 includes motor 126 and inverter 134. Energy storage device 132 can be a traction battery (e.g., a battery or traction battery that supplies power to propel the vehicle), capacitor, inductor, or other energy storage device. Power flowing into electric drive system 135 can be monitored via current sensor 145 and voltage sensor 146. The position and rotational speed of motor 126 can be monitored via position sensor 147. Torque generated by motor 126 can be monitored via torque sensor 148.

[0025] In some examples, the energy storage device 132 may be configured to store electrical energy that can be supplied to other electrical loads residing on the vehicle (in addition to the motor), including the cabin heating and air conditioning system, the engine starting system, the headlight system, the cabin audio and video system, etc.

[0026] The control system 114 can communicate with the motor 126, the energy storage device 132, etc. The control system 114 can receive sensor feedback information from the electric drive system 135 and the energy storage device 132, etc. Furthermore, the control system 114 can send control signals to the electric drive system 135 and the energy storage device 132, etc., in response to the sensor feedback. The control system 114 can receive instructions from a human operator 102 (e.g., a user) or an autonomous controller regarding operator-requested outputs of the vehicle propulsion system. For example, the control system 114 can receive sensor feedback from a pedal position sensor 194 communicating with a pedal 192. Pedal 192 can schematically represent a pedal requested by the driver. Similarly, the control system 114 can receive instructions from an operator requesting vehicle deceleration via a human operator 102 or an autonomous controller. For example, the control system 114 can receive sensor feedback from a pedal position sensor 157 communicating with a vehicle brake caliper control pedal 156.

[0027] The energy storage device 132 can periodically receive power via a power converter 12 and a socket 11. The socket 11 can receive power from a vehicle charger 6, which is located remotely to the vehicle 121 (e.g., externally). The vehicle charger 6 can wirelessly communicate with the vehicle 121 via a transceiver 7, and may include an optional HMI 3 (human / machine interface, such as a display and / or keyboard). Alternatively, the vehicle charger 6 can communicate with the vehicle 121 via a charging cable 8 (e.g., a wired connection). The vehicle charger 6 can receive power from a stationary power grid 5. The vehicle charger 6 includes a non-transitory (e.g., read-only memory) 65, random access memory 66, digital input / output 68, and a microcontroller 67. The microcontroller 67 can send and receive messages via the transceiver 7. As a non-limiting example, the drivetrain 100 can be configured as a plug-in electric vehicle (EV), thereby supplying electrical energy to the energy storage device 132 via a power grid (not shown). Alternatively, the vehicle 121 can be a plug-in hybrid vehicle.

[0028] The energy storage device 132 (e.g., a battery) includes an energy storage device controller 139. The energy storage device controller 139 provides charge balancing between energy storage elements (e.g., battery cells) and communication with other vehicle controllers (e.g., controller 112). The energy storage device controller 139 may include a processor 139a, a random access memory 139b, a non-transitory read-only memory 139c, and inputs and outputs 139d (e.g., analog and digital inputs and outputs).

[0029] One or more wheel speed sensors (WSS) 195 may be coupled to one or more wheels of the drivetrain 100. The wheel speed sensors can detect the rotational speed of each wheel. Such an example of a WSS may include a sensor of the permanent magnet type.

[0030] Controller 112 may form part of control system 114. In some examples, controller 112 may be a single controller for the vehicle. Control system 114 is shown receiving information from multiple sensors 116 (various examples of which are described herein) and sending control signals to multiple actuators 181 (various examples of which are described herein). As an example, sensor 116 may include a tire pressure sensor (not shown), wheel speed sensor 195, etc. In some examples, sensors associated with motor 126, wheel speed sensor 195, etc., may transmit information to controller 112 about various states of motor operation. Controller 112 includes non-transitory (e.g., read-only memory) 165, random access memory 166, digital input / output 168, and microcontroller 167. Infotainment system 140 (e.g., human / machine interface) may receive input data from human 102 and may display messages and data to human 102. Infotainment system 140 may communicate with controller 112 via network 199 (e.g., controller area network (CAN) or Ethernet network). The infotainment system 140 and / or controller 112 may also communicate with camera 142 and audible actuator 141 (e.g., speaker or other sound exciter) via network 199. Although one camera is shown, it will be understood that the vehicle may include multiple cameras providing different views of the area around the vehicle 121. Controller 112 may communicate with vehicle charger 6 via transceiver 164.

[0031] Now for reference Figure 2 The image shows a perspective view of an example battery test bench used to evaluate battery temperature control. In this example, the energy storage device 132 (battery) includes an electric heater 202 for simulating an increase in battery temperature due to battery cell degradation, a plurality of battery cell groups 204, and an insulator 206 positioned between each of the battery cell groups 204. The battery cell groups 204 may include a plurality of battery cells.

[0032] Temperature sensor 208 is shown arranged to sense the temperature at each battery cell group 204. The temperature sensor may supply temperature data to a controller and / or a data acquisition system (not shown).

[0033] Now for reference Figure 3 , showed Figure 2 The graph shows the battery's operating condition. The vertical lines at times t1, t1+50 seconds, and t1+200 seconds represent the times of interest during the sequence. The threshold 350 (dash) represents the threshold temperature. If the temperature of the battery cell assembly exceeds the threshold 350, this may be an indication of degradation of the battery cell or battery cell assembly. Times t0, t1, t1+50 seconds, etc., are only applicable to... Figure 3 The sequence is not applicable to the timing of other figures included herein.

[0034] from Figure 3 The first graph at the top is a graph of battery cell exhaust gas flow rate versus time. The vertical axis represents the battery cell exhaust gas flow rate (e.g., the flow rate of gas emitted from a deteriorated battery cell or cell assembly), and the battery cell exhaust gas flow rate increases in the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left side of the graph to the right side. Trace 302 (dash line) represents the temperature of battery cell assembly one. Battery cell assembly one and... Figure 2 The electric heater 202 shown is adjacent to and closest to the battery cell group. Trace 304 (dotted line) represents the temperature of battery cell group two. Battery cell group two is adjacent to and closest to battery cell group one.

[0035] from Figure 3 The second graph from the top is a graph of battery cell temperature versus time. The vertical axis represents battery cell temperature, and the battery cell temperature increases along the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left side of the graph to the right side. Trace 306 (solid line) represents the temperature of heater 202. Trace 308 (dashed line) represents the temperature of battery cell group one. Trace 310 (dotted-dashed line) represents the temperature of battery cell group two.

[0036] At time t0, the electric heater is activated and its temperature begins to rise. The exhaust gas flow rate of battery cell group one is zero, and the exhaust gas flow rate of battery cell group two is zero. The temperature of battery group one begins to rise slowly. The temperature of battery group two remains at a low level.

[0037] At time t1, the electric heater remains active and its temperature has stabilized at a high level. The temperature of battery cell group one exceeds the threshold of 350°C, and therefore the exhaust gas flow rate of battery cell group one begins to increase at a relatively high rate shortly thereafter. The exhaust gas flow rate of battery cell group two remains constant. The temperature of battery group two is at a low level.

[0038] Between time t1 and time t1+50 seconds, the electric heater remains active and its temperature has stabilized at a high level. The temperature of battery cell group one remains above the threshold of 350°C, and the exhaust gas flow rate of battery cell group one rises to a high level and then begins to decrease as the gas leaves battery cell group one and enters the battery casing. The exhaust gas flow rate of battery cell group two remains constant. The temperature of battery group two remains at a low level. As the pressure in the battery casing begins to increase due to the exhaust of battery cell group one, the gas in the battery casing can be released.

[0039] At time t1+50 seconds, the electric heater remains active and its temperature has stabilized at a high level. The temperature of battery cell group one remains above the threshold of 350°C, and the exhaust gas flow rate of battery cell group one has decreased to near zero. The exhaust gas flow rate of battery cell group two remains low. The temperature of battery group two is at a low level.

[0040] The inventors of this paper have recognized that the period between time t1+50 seconds and time t1+200 seconds provides an opportunity to increase cooling of the battery cell group before the next adjacent battery cell group exceeds a threshold of 350. Increasing cooling of the battery cells within this time window allows the cells to be cooled with less mixing of battery gas and dielectric fluid. Therefore, peak pressures in the battery can be reduced, and lower thermal stress can be applied to the battery cooling system components. Furthermore, heat transfer between battery cell groups can be interrupted more quickly, making it easier to cool other battery cell groups.

[0041] At time t1+200 seconds, the electric heater remains active and its temperature remains stable at a high level. The temperature of battery cell group one remains above the threshold of 350°C, and the exhaust gas flow rate of battery cell group one has decreased to near zero. The temperature of battery group two exceeds the threshold of 350°C, and the temperature in battery cell group two begins to rise shortly thereafter because no additional coolant flows to the battery.

[0042] Now for reference Figure 4 The diagram shows a perspective view of an example battery cooling system. The battery cooling system 400 includes a reservoir 401 for storing a dielectric liquid 402 (coolant). A conduit or pipe 406 extends between the reservoir 401 and the battery housing 407. A pump 412 and a valve 404 are available via... Figure 1 The controller 139 is selectively activated. Pump 412 and valve 404 are shown positioned along conduit or pipe 406. Return conduit 408 also provides fluid communication between reservoir 401 and battery housing 407. Temperature sensor 410 is shown at housing outlet 430 near pressure relief valve 432. Temperature sensor 208 is shown arranged to sense the temperature at each battery cell assembly 204. The temperature sensor can... Figure 1 The controller 139 supplies temperature data. In an alternative example, a pressure sensor may be set... Figure 4 The location of the temperature sensor is shown in the image.

[0043] In response to the battery cell pack temperature exceeding a threshold temperature, pump 412 can be activated and / or its rotational speed can be increased. Furthermore, according to... Figure 7 and Figure 9 Alternatively, valve 404 can be opened to cool the battery cell pack 204.

[0044] therefore, Figure 1 and Figure 4 The system provides a battery operating system comprising: one or more battery cells; a pump and a reservoir; a dielectric fluid; and a controller including executable instructions stored in a non-transitory memory, the executable instructions causing the controller to enter a battery temperature control mode in response to a battery condition exceeding a first threshold, to increase the pump output in response to a battery condition falling below a second threshold, and to decrease the pump output in response to a battery condition falling below a third threshold. In a first example, the battery operating system includes: wherein the battery condition is battery temperature. In a second example that may include the first example, the battery operating system includes: wherein the battery condition is battery pressure. In a third example that may include one or both of the first and second examples, the battery operating system further includes additional executable instructions causing the controller to open a valve in response to a battery condition falling below a second threshold. In a fourth example that may include one or more of the first to third examples, the battery operating system further includes additional executable instructions causing the controller to close a valve in response to a battery condition falling below a third threshold. In a fifth example that may include one or more of the first to fourth examples, the battery operating system further includes an exhaust valve. In a sixth example, which may include one or more of the first to fifth examples, the battery operating system includes: a second threshold indicating that gas is discharged from the battery casing via an exhaust valve. In a seventh example, which may include one or more of the first to sixth examples, the battery operating system includes: an exhaust valve located at an outlet on the battery casing.

[0045] Now go to Figure 5 An example control sequence for cooling the traction battery is shown. Figure 5 The sequence can be applied to Figure 1 and Figure 4 The system. Figure 5 Includes three graphs and a vertical line showing the times of interest. Times t0, t1, t1+50 seconds, etc., are only applicable to... Figure 5 The sequence is not applicable to the timing of other figures included herein.

[0046] from Figure 5 The first graph, starting from the top, is a graph of temperature versus time at the battery casing's exit or outlet. Trace 502 represents the temperature at the battery casing's outlet (e.g., the temperature measured via sensor 410). The vertical axis represents temperature, and the temperature increases along the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left side of the graph to the right side.

[0047] from Figure 5The second graph from the top is a graph of pump operating status versus time. Trace 504 represents a pump that can supply dielectric fluid to the battery casing (e.g., Figure 4 The pump operating status is shown in Figure 412. The vertical axis represents the pump operating status, and the pump is activated and rotating when trace 504 is at a higher level near the arrow on the vertical axis. The pump is deactivated when trace 504 approaches the horizontal axis. The horizontal axis represents time, and time increases from the left side of the figure to the right side.

[0048] from Figure 5 The third curve from the top is a graph of battery cell pack temperature versus time. Trace 506 represents the temperature at the location of the degraded battery cell pack. Trace 508 represents the temperature at the location of the battery cell pack that is close to or adjacent to the degraded battery cell pack. The vertical axis represents the battery cell pack temperature, and the battery cell pack temperature increases in the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left side of the graph to the right side. The threshold 550 (dash line) indicates the threshold temperature at which the battery cell pack degrades when the temperature exceeds the threshold value of 550.

[0049] At time t0, the temperature at the battery casing outlet is low and the dielectric coolant pump is off. The temperature of the degraded battery cell group is low, as is the temperature of the battery cell group adjacent to the degraded battery cell group. Shortly after time t0, the temperature of the degraded battery begins to rise.

[0050] At time t1, the temperature at the outlet of the battery casing remains low and the dielectric coolant pump is off. The temperature of the degraded battery cell group now exceeds the threshold 550 to indicate that the battery cell group is undergoing degradation (e.g., a decrease in performance, storage capacity, power supply capacity, etc.), and the temperature of the battery cell group adjacent to the degraded battery cell group is lower.

[0051] Between time t1 and time t1+50 seconds, the temperature inside the battery casing rises, and the pressure valve controlling the pressure inside the battery casing opens to allow gas to escape from the battery casing (not shown). The temperature at the outlet of the battery casing rises and then tends to stabilize at a relatively high level before beginning to decrease. The dielectric coolant pump shuts off, thereby reducing the mixing of coolant and gas, which in turn lowers the pressure and temperature inside the battery casing. The temperature of the degraded battery cell group reaches a high level and then tends to stabilize. The temperature of the battery cell group adjacent to the degraded battery cell group rises slowly.

[0052] At time t1+50 seconds (e.g., time t1 plus 50 seconds), the temperature inside the battery casing gradually decreases, and the dielectric coolant pump is activated to cool the battery cell assembly. The temperature of the battery cell assembly experiencing degradation remains at a higher level. The temperature of the battery cell assembly adjacent to the degraded battery cell assembly continues to rise slowly.

[0053] At time t1+200 seconds (e.g., time t1+200 seconds), the temperature inside the battery casing drops to a low level, thus deactivating the dielectric coolant pump. The temperature of the degraded battery cell group has decreased below the threshold of 550°C. The temperature of the battery cell groups adjacent to the degraded battery cell group does not exceed the threshold of 550°C, thereby preventing the spread of degradation from adjacent battery cell groups.

[0054] Therefore, by delaying the introduction of dielectric coolant into a group of battery cells, the degradation of the additional battery cells can be reduced. This delay allows gases generated as the temperature rises within the deteriorating battery cells to escape from the battery casing. This reduces the mixing of gases and coolant within the battery, thereby lowering the pressure inside the battery. Consequently, the dielectric coolant can cool the battery cells more effectively because it transfers less heat from the released gases. Furthermore, the pressure inside the battery casing is reduced compared to immediately delivering coolant to the battery pack in response to the battery cells exceeding a threshold temperature. This reduces the likelihood of battery casing deformation and helps lower the temperature inside the battery casing.

[0055] Understandable, despite Figure 5 The description outlines a temperature-based control strategy, but similar performance can be achieved by responding to pressure within the battery cell pack and battery casing instead of temperature. For example, pressure within the battery casing could replace... Figure 5 The pressure in the first curve from the top, and the battery cell pack pressure can be replaced from... Figure 5 The battery cell temperature is shown in the third curve from the top. Additionally, it can be understood that for different batteries, times t1+50 seconds and t1+200 seconds may differ from t1+50 seconds and t1+200 seconds. For example, an action taken at time t1+50 seconds may be taken at time t1+45 or 55 seconds.

[0056] Now go to Figure 6 It shows the method for using according to Figure 7 An example control sequence for cooling the traction battery. Figure 6 The sequence can be applied to Figure 1 and Figure 4 The system. Figure 6 Includes three graphs and a vertical line showing the times of interest. Times t0, t1, t1+50 seconds, etc., are only applicable to... Figure 6The sequence is not applicable to the timing of other figures included herein.

[0057] from Figure 6 The first graph, starting from the top, is a graph of temperature versus time at the outlet or drain of the battery casing. Trace 602 represents the temperature at the outlet of the battery casing (e.g., the temperature measured via sensor 410). The vertical axis represents temperature, and the temperature increases in the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left side of the graph to the right side. Threshold 650 (dashed line) represents the threshold temperature below which the dielectric pump is deactivated after it has been recently activated.

[0058] from Figure 6 The second graph from the top is a graph of pump operating status versus time. Trace 604 represents a pump that can supply dielectric fluid to the battery casing (e.g., Figure 4 The pump operating status is shown in Figure 412. The vertical axis represents the pump operating status, and the pump is activated and rotating when trace 604 is at a higher level near the arrow on the vertical axis. The pump is deactivated when trace 604 approaches the horizontal axis. The horizontal axis represents time, and time increases from the left side of the figure to the right side.

[0059] from Figure 6 The third curve from the top is a graph of battery cell pack temperature versus time. Trace 606 represents the temperature at the location of the degraded battery cell pack. Trace 608 represents the temperature at the location of the battery cell pack that is close to or adjacent to the degraded battery cell pack. The vertical axis represents the battery cell pack temperature, and the battery cell pack temperature increases in the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left side of the graph to the right side. Threshold 652 (dashed line) indicates the threshold temperature at which the battery cell temperature exceeds threshold 652, indicating the threshold temperature at which the battery cell pack degrades.

[0060] At time t0, the temperature at the battery casing outlet is low and the dielectric coolant pump is off. The temperature of the degraded battery cell group is low, as is the temperature of the battery cell group adjacent to the degraded battery cell group. Shortly after time t0, the temperature of the degraded battery begins to rise.

[0061] At time t1, the temperature at the outlet of the battery casing remains low and the dielectric coolant pump is off. The temperature of the degraded battery cell group now exceeds the threshold 652 to indicate that the battery cell group is undergoing degradation (e.g., a decrease in performance, storage capacity, power supply capacity, etc.), and the temperature of the battery cell group adjacent to the degraded battery cell group is lower.

[0062] Between time t1 and time t1+50 seconds, the temperature inside the battery casing rises, and the pressure valve controlling the pressure inside the battery casing opens to allow gas to escape from the battery casing (not shown). The temperature at the outlet of the battery casing rises and then tends to stabilize at a relatively high level before beginning to decrease. The dielectric coolant pump shuts off, thereby reducing the mixing of coolant and gas, which in turn lowers the pressure and temperature inside the battery casing. The temperature of the degraded battery cell group reaches a high level and then tends to stabilize. The temperature of the battery cell group adjacent to the degraded battery cell group rises slowly.

[0063] At time t1+50 seconds, the temperature inside the battery casing gradually decreases, and the dielectric coolant pump is activated to cool the battery cell assembly. The temperature of the degraded battery cell assembly also decreases. The temperature of the battery cell assembly adjacent to the degraded battery cell assembly continues to rise slowly.

[0064] At time t2, the temperature inside the battery casing has decreased below the second threshold of 650°C, therefore the dielectric coolant pump is deactivated. The temperature of the degraded battery cell group has decreased below the threshold of 652°C. The temperature of the battery cell group adjacent to the degraded battery cell group does not exceed the threshold of 652°C, thereby preventing the spread of deterioration between adjacent battery cell groups.

[0065] Therefore, similar to Figure 5 The sequence, which delays the introduction of dielectric coolant into a group of battery cells, allows for reduced degradation of additional battery cells. However, in this example, the pump remains active until the temperature at the battery outlet is below a threshold temperature, providing verification that increased thermal conditions can actually be suppressed. Additionally, Figure 5 The sequence can save time pumping dielectric fluid through the battery because the method does not deactivate the pump based solely on the time since the temperature most recently exceeded the threshold.

[0066] Now for reference Figure 7 This illustrates a method for controlling the traction battery. Figure 7 The method can be combined with executable instructions stored in the controller's non-transitory memory. Figure 1 and Figure 4 In the system. Figure 7 The method can generate Figure 6 sequence. Figure 7 The method can be with Figure 1 and Figure 4 The system collaborates to enable the controller to monitor sensors and adjust actuators in the real world. Method 7 can be performed when the dielectric fluid does not surround the array of battery cell groups, or when the dielectric fluid surrounds the array of battery cell groups.

[0067] At 702, method 700 determines whether the temperature (T) of the battery cell assembly or battery cell is greater than a predetermined threshold temperature (T threshold). If yes, the answer is yes, and method 700 proceeds to 704. Otherwise, the answer is no, and method 700 returns to 702, or alternatively exits. A temperature exceeding the threshold temperature indicates degradation of the battery cell assembly or battery cell.

[0068] At 704, method 700 records the current time (e.g., the time when the temperature of the battery cell assembly exceeds a threshold temperature) as time t1. Method 700 proceeds to 706.

[0069] At point 706, method 700 determines the amount of time that has elapsed since the temperature of the battery cell assembly recently exceeded a threshold temperature. To make this determination, method 700 starts from the current time (e.g., t). 当前 Subtract time t1. The result is stored in a variable named Dt. Method 700 proceeds to 708.

[0070] At 708, the pump (e.g., Figure 4 (412) is closed and does not rotate. Additionally, the cooling valve (e.g., Figure 4 (404). Method 700 proceeds to 710.

[0071] At 710, if the dielectric fluid surrounds the array of battery cells, method 700 discharges the mixture of gas and dielectric fluid generated by the battery cells via a pressure relief valve. If the dielectric fluid does not surround the array of battery cells, the pressure relief valve can release gas from the battery casing. The pressure relief valve can control the pressure in the battery casing without controller assistance. Method 700 proceeds to 712.

[0072] At 712, method 700 determines whether the value of Dt is greater than a predetermined threshold time amount. If yes, the answer is yes, and method 700 proceeds to 714. Otherwise, the answer is no, and method 700 returns to 706. In one example, the predetermined time amount can be empirically determined by causing degradation of one or more battery cell groups and determining the amount of time required for the temperature of the degraded battery cell group to begin to decrease after it begins to rise due to, for example, thermal degradation of the battery cell group. In some examples, the predetermined time amount can vary according to changes in the state of charge (SOC) of the battery cell group. For example, the threshold temperature can be a first value for a first SOC and a second value for a second SOC, where the first value is less than the second value, and the first SOC is less than the second SOC. Alternatively, the predetermined threshold time amount can also be based on the charge storage capacity of the battery cell group and / or other battery cell group properties.

[0073] At 714, method 700 activates the dielectric pump (e.g., Figure 4 (412). The pump can be activated via a battery controller. If the dielectric pump is already activated, its rotational speed can be increased. Method 700 proceeds to 716.

[0074] At 716, method 700 begins to increase the flow rate of the dielectric fluid to the battery casing and the array surrounding the battery cell assembly. In one example, increasing the flow rate of the dielectric fluid to the battery casing includes opening or further opening a valve (e.g., valve 404). Method 700 proceeds to 718.

[0075] At 718, method 700 includes returning the dielectric fluid to the reservoir, such that the dielectric fluid flows through a return conduit (e.g., Figure 4 (408) Leave. Method 700 proceeds to 718.

[0076] At 720, method 700 determines whether, after the battery cell assembly temperature has exceeded a first threshold temperature and then a second threshold temperature, the battery cell assembly temperature is still greater than the second threshold temperature (e.g., ...). Figure 6 (650). If no, the answer is no, and method 700 proceeds to 722. Otherwise, the answer is yes, and method 700 returns to 714.

[0077] At 722, method 700 stops the rotation of the dielectric liquid pump. Alternatively, method 700 may close a valve in the battery cooling system or reduce the opening of said valve. This saves power and prepares the pump for further increases in battery temperature that may occur later. Method 900 proceeds to exit.

[0078] In this way, method 700 allows for the removal of gas or a mixture of gas and liquid from the battery casing before increasing the flow rate of dielectric liquid to the battery cells. The pump can be activated based on the time elapsed since the temperature of the battery exceeded a first threshold temperature, indicating battery degradation. The pump can be deactivated after the temperature of the battery cell assembly drops below the second threshold temperature, after the temperature of the battery cell assembly has exceeded both the first and second threshold temperatures.

[0079] Now go to Figure 8 It shows the method for using according to Figure 9 An example control sequence for cooling the traction battery. Figure 8 The sequence can be applied to Figure 1 and Figure 4 The system. Figure 8 Includes three graphs and a vertical line showing the times of interest. Times t0, t1, t2, and t3 are only applicable to... Figure 8 The sequence is not applicable to the timing of other figures included herein.

[0080] from Figure 8The first graph, starting from the top, is a graph of temperature versus time at the outlet or drain of the battery casing. Trace 802 represents the temperature at the outlet of the battery casing (e.g., the temperature measured via sensor 410). The vertical axis represents temperature, and the temperature increases in the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left side of the graph to the right side. Threshold 850 (dashed line) represents the threshold temperature below which the dielectric pump is deactivated after it has been recently activated.

[0081] from Figure 8 The second graph from the top is a graph of pump operating status versus time. Trace 804 represents a pump that can supply dielectric fluid to the battery casing (e.g., Figure 4 The pump operating status is shown in Figure 412. The vertical axis represents the pump operating status, and the pump is activated and rotating when trace 804 is at a higher level near the arrow on the vertical axis. The pump is deactivated when trace 804 approaches the horizontal axis. The horizontal axis represents time, and time increases from the left side of the figure to the right side.

[0082] from Figure 8 The third graph from the top is a graph of battery cell pack temperature versus time. Trace 806 represents the temperature at the location of the degraded battery cell pack. Trace 808 represents the temperature at the location of the battery cell pack that is close to or adjacent to the degraded battery cell pack. The vertical axis represents the battery cell pack temperature, and the battery cell pack temperature increases in the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left side of the graph to the right side. Threshold 852 (dashed line) represents the threshold temperature at which the battery cell pack temperature exceeds the value of threshold 852, indicating the threshold temperature at which the battery cell pack degrades. Threshold 854 (dashed line) represents a second threshold temperature, which indicates that the battery cell pack undergoing degradation has depleted a large amount of its heat-generating compounds.

[0083] At time t0, the temperature at the battery casing outlet is low and the dielectric coolant pump is off. The temperature of the degraded battery cell group is low, as is the temperature of the battery cell group adjacent to the degraded battery cell group. Shortly after time t0, the temperature of the degraded battery begins to rise.

[0084] At time t1, the temperature at the outlet of the battery casing remains low and the dielectric coolant pump is off. The temperature of the degraded battery cell group now exceeds the threshold 852 to indicate that the battery cell group is undergoing degradation (e.g., a decrease in performance, storage capacity, power supply capacity, etc.), and the temperature of the battery cell group adjacent to the degraded battery cell group is lower.

[0085] Between time t1 and time t2, the temperature inside the battery casing rises, and the pressure relief valve controlling the pressure inside the battery casing opens to release gas (not shown). The temperature at the outlet of the battery casing rises and then tends to stabilize at a relatively high level before beginning to decrease. The dielectric coolant pump shuts off, thereby reducing the mixing of coolant and gas, which in turn lowers the pressure and temperature inside the battery casing. The temperature of the degraded battery cell assembly reaches a high level and then tends to stabilize. The temperature of the battery cell assembly adjacent to the degraded battery cell assembly rises slowly.

[0086] At time t2, the temperature inside the battery casing gradually decreases. In response to the temperature of the battery cell assembly undergoing degradation dropping below threshold 854 (e.g., the second threshold temperature) after having risen above the first and second threshold temperatures, the dielectric coolant pump is activated.

[0087] At time t3, the temperature inside the battery casing has dropped below a threshold of 850 (e.g., a temperature threshold), therefore the dielectric coolant pump is deactivated. The temperature of the degraded battery cell group has dropped below the threshold of 850. The temperature of the battery cell group adjacent to the degraded battery cell group does not exceed the threshold of 852. This prevents the spread of degradation to adjacent battery cell groups.

[0088] Therefore, similar to Figure 6 The sequence of delaying the introduction of dielectric coolant into a group of battery cells allows for reduced degradation of additional battery cell groups. However, in this example, the pump is activated in response to the temperature of the battery cell group undergoing degradation dropping below a threshold of 854. This allows for a shorter duration of pump operation, thereby saving power and the cooling capacity of the dielectric fluid.

[0089] Now for reference Figure 9 This illustrates a method for controlling the traction battery. Figure 9 The method can be combined with executable instructions stored in the controller's non-transitory memory. Figure 1 and Figure 4 In the system. Figure 9 The method can generate Figure 8 sequence. Figure 9 The method can be with Figure 1 and Figure 4 The system collaborates to enable the controller to monitor sensors and adjust actuators in the real world. Method 9 can be performed when the dielectric fluid does not surround the array of battery cell groups, or when the dielectric fluid surrounds the array of battery cell groups.

[0090] At 902, method 900 determines whether the temperature (T) of the battery cell assembly or battery cell is greater than a predetermined threshold temperature (T threshold, for example, Figure 8(852). If yes, the answer is yes, and method 900 proceeds to 904. Otherwise, the answer is no, and method 900 returns to 902, or exits instead. A battery cell or battery cell assembly temperature exceeding a threshold temperature indicates battery cell or battery cell degradation.

[0091] At 904, method 900 records the current time (e.g., the time when the temperature of the battery cell assembly exceeds the threshold temperature) as time t1. Method 900 proceeds to 906.

[0092] At 906, the pump (e.g., Figure 4 (412) is closed and does not rotate. Additionally, the cooling valve (e.g., Figure 4 (404). Method 900 proceeds to 908.

[0093] At 908, if the dielectric fluid surrounds the array of battery cells, method 900 discharges the mixture of gas and dielectric fluid generated by the battery cells via a pressure relief valve. If the dielectric fluid does not surround the array of battery cells, the pressure relief valve can release gas from the battery casing. The pressure relief valve can control the pressure in the battery casing without controller assistance. Method 900 proceeds to 910.

[0094] At 910, method 900 constrains the mixing of gas and dielectric liquid by preventing an increase in the flow rate of dielectric liquid to the array of battery cells. In one example, the mixing of gas and dielectric liquid can be constrained by closing or maintaining the position of a valve (e.g., 404). Method 900 proceeds to 912.

[0095] At 912, method 900 determines that the temperature of the battery cell assembly recently exceeded a first threshold temperature and a second threshold temperature (e.g., Figure 8 After step 854, is the temperature of the battery cell assembly greater than the second threshold temperature? If yes, the answer is yes, and method 900 returns to 906. If no, the answer is no, and method 900 proceeds to 914.

[0096] At position 914, method 900 activates the dielectric pump (e.g., Figure 4 (412). The pump can be activated via a battery controller. If the dielectric pump is already activated, its rotational speed can be increased. Method 900 proceeds to 916.

[0097] At 916, method 900 begins to increase the flow rate of the dielectric fluid to the battery casing and the array surrounding the battery cell assembly. In one example, increasing the flow rate of the dielectric fluid to the battery casing includes opening or further opening a valve (e.g., valve 404). Method 900 proceeds to 918.

[0098] At 918, method 900 determines whether the temperature at the outlet of the battery casing is less than or equal to a threshold temperature (e.g., Figure 8 If yes, the answer is yes, and method 900 returns to 914. If no, the answer is no, and method 900 proceeds to 920.

[0099] At 920, method 900 stops the rotation of the dielectric liquid pump. Alternatively, method 900 may close a valve in the battery cooling system or reduce the opening of said valve. This saves power and prepares the pump for further increases in battery temperature that may occur later. Method 900 proceeds to exit.

[0100] In this way, method 700 allows for the removal of gas or a mixture of gas and liquid from the battery casing before increasing the flow rate of the dielectric fluid to the battery cells. The pump can be activated based on a pressure drop following an increase in pressure at the battery cell assembly.

[0101] Figure 7 and Figure 9 The method provides a method for a battery, the method comprising: increasing the flow rate of dielectric fluid flowing to the battery in response to an indication of battery condition exceeding a threshold and after a predetermined threshold time elapsed since the most recent indication of battery condition exceeding the threshold, via a controller. In a first example, the method includes: wherein the threshold is a temperature that varies with the state of charge of the battery. In a second example that may include the first example, the method includes: wherein the battery condition is the battery temperature. In a third example that may include one or both of the first and second examples, the method includes: wherein the battery temperature is indicated via a temperature sensor at the dielectric fluid outlet of the battery. In a fourth example that may include one or more of the first to third examples, the method includes: wherein the battery condition is the battery pressure. In a fifth example that may include one or more of the first to fourth examples, the method includes: wherein the dielectric fluid flow rate is increased by increasing the speed of a pump or opening a valve. In a sixth example that may include one or more of the first to fifth examples, the method further includes decreasing the dielectric fluid flow rate in response to a second predetermined threshold time elapsed since the most recent indication of battery condition exceeding the threshold.

[0102] Figure 7 and Figure 9The method also provides a method for a battery, the method comprising: detecting degradation of a battery cell and removing at least a portion of the gas generated via the battery cell via a pressure relief valve; and increasing the flow rate of dielectric fluid to the battery via a controller in response to an indication that at least said portion of the gas generated via the battery cell has been removed from the battery. In a first example, the method comprises: detecting degradation of the battery cell based on battery temperature or pressure. In a second example that may include the first example, the method comprises: wherein the indication that at least said portion of the gas generated via the battery cell has been removed is based on an amount of time since degradation of the battery cell was detected. In a third example that may include one or both of the first and second examples, the method comprises: wherein the indication that at least said portion of the gas generated via the battery cell has been removed is based on a pressure drop in the battery below a threshold pressure. In a fourth example that may include one or more of the first to fourth examples, the method further comprises reducing the flow rate of dielectric fluid to the battery in response to the temperature of the battery.

[0103] It should be noted that the example control and estimation routines included herein can be used with various vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in non-transitory memory and can be executed by a control system including one or more controllers in conjunction with various sensors, actuators, and other engine hardware. The specific routines described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, etc. Therefore, the various actions, operations, and / or functions shown can be executed in the shown sequence, in parallel, or in some cases omitted. Similarly, the processing order is not necessarily necessary to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations, and / or functions shown can be repeatedly executed according to the specific strategy used. Furthermore, at least a portion of the described actions, operations, and / or functions can be graphically represented as code to be programmed into a non-transitory memory of a computer-readable storage medium in a control system. When the described actions are executed by executing instructions in conjunction with one or more controllers in a system including various engine hardware components, the control actions can also change the operating state of one or more sensors or actuators in the physical world.

[0104] This specification concludes here. Many variations and modifications will arise in those skilled in the art upon reading this specification without departing from its spirit and scope. For example, electric and hybrid vehicle configurations may benefit from this specification.

[0105] According to this disclosure, a method for a battery includes: increasing the flow rate of a dielectric fluid to the battery in response to an indication of a battery condition exceeding a threshold and after a predetermined threshold time elapsed since the most recent indication of the battery condition exceeding the threshold.

[0106] In one aspect of the invention, the threshold is a temperature that varies with the state of charge of the battery.

[0107] In one aspect of the invention, the battery condition is the battery temperature.

[0108] In one aspect of the invention, the battery temperature is indicated via a temperature sensor at the dielectric liquid outlet of the battery.

[0109] In one aspect of the invention, the battery condition is battery pressure.

[0110] In one aspect of the invention, the flow rate of the dielectric fluid is increased by increasing the speed of the pump or by opening a valve.

[0111] In one aspect of the invention, the method includes reducing the dielectric fluid flow rate in response to a second predetermined threshold time elapsed since the indication of the most recent battery condition exceeded the threshold.

[0112] According to the present invention, a battery operating system is provided, the battery operating system comprising: one or more battery cells; a pump and a reservoir; a dielectric fluid; and a controller, the controller including executable instructions stored in a non-transitory memory, the executable instructions causing the controller to: enter a battery temperature control mode in response to a battery condition exceeding a first threshold, increase the output of the pump in response to a battery condition falling below a second threshold, and decrease the output of the pump in response to a battery condition falling below a third threshold.

[0113] According to an embodiment, the battery operating condition is the battery temperature.

[0114] According to an embodiment, the battery operating condition is the battery pressure.

[0115] According to an embodiment, the invention is further characterized by an additional executable instruction that causes the controller to open the valve in response to the battery condition being less than the second threshold.

[0116] According to an embodiment, the invention is further characterized by the addition of executable instructions that cause the controller to close the valve in response to the battery condition being less than the third threshold.

[0117] According to an embodiment, the invention is further characterized by including an exhaust valve.

[0118] According to an embodiment, the second threshold indicates that gas is discharged from the battery casing via the exhaust valve.

[0119] According to an embodiment, the vent valve is located at the vent outlet of the battery casing.

[0120] According to the present invention, a method for a battery includes: detecting degradation of a battery cell and removing at least a portion of the gas generated via the battery cell via a pressure relief valve; and increasing the flow rate of a dielectric liquid to the battery via a controller in response to an indication that at least said portion of the gas generated via the battery cell has been removed from the battery.

[0121] In one aspect of the invention, the degradation of the battery cell is detected based on battery temperature or pressure.

[0122] In one aspect of the invention, the indication that at least a portion of the gas generated via the battery cell has been removed is based on the amount of time since the degradation of the battery cell was detected.

[0123] In one aspect of the invention, the indication that at least a portion of the gas generated via the battery cell has been removed is based on the pressure dropping below a threshold pressure.

[0124] In one aspect of the invention, the method includes reducing the flow rate of the dielectric liquid flowing to the battery in response to the temperature of the battery.

Claims

1. A method for a battery, the method comprising: increasing a flow of dielectric liquid to the battery via a controller in response to an indication of a battery condition exceeding a threshold and a predetermined threshold amount of time elapsing since a last time the indication of the battery condition exceeded the threshold.

2. The method for the battery of claim 1, wherein the threshold is a temperature that varies with a state of charge of the battery.

3. The method for the battery of claim 1, wherein the battery condition is a battery temperature.

4. The method for the battery of claim 3, wherein the battery temperature is indicated via a temperature sensor at a dielectric liquid outlet of the battery.

5. The method for the battery of claim 1, wherein the battery condition is a battery pressure.

6. The method for the battery of claim 1, wherein the flow of dielectric liquid is increased via increasing a speed of a pump or opening a valve.

7. The method for the battery of claim 1, further comprising decreasing a dielectric liquid flow in response to a second predetermined threshold amount of time elapsing since the last time the indication of the battery condition exceeded the threshold.

8. A battery operating system, the battery operating system comprising: one or more battery cells; a pump and a reservoir; a dielectric fluid; and a controller comprising executable instructions stored in non-transitory memory that cause the controller to enter a battery temperature control mode in response to a battery condition exceeding a first threshold, increase an output of the pump in response to the battery condition being less than a second threshold, and decrease the output of the pump in response to the battery condition being less than a third threshold.

9. The battery operating system of claim 8, wherein the battery condition is a battery temperature.

10. The battery operating system of claim 8, wherein the battery condition is a battery pressure.

11. The battery operating system of claim 8, further comprising additional executable instructions that cause the controller to open a valve in response to the battery condition being less than the second threshold.

12. The battery operating system of claim 11, further comprising additional executable instructions that cause the controller to close the valve in response to the battery condition being less than the third threshold.

13. The battery operating system of claim 8, further comprising a vent valve.

14. The battery operating system of claim 13, wherein the second threshold indicates a discharge of gas from a battery enclosure via the vent valve.

15. The battery operating system of claim 14, wherein the vent valve is positioned at a vent outlet of the battery enclosure. ​

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