Active heat sharing between cabin and high voltage battery

Abstract

The present disclosure provides active heat sharing between a cabin and a high voltage battery. A vehicle includes a traction battery and an electric machine powered by the traction battery and configured to power wheels of the vehicle. The vehicle also includes a thermal management system having: a battery circuit configured to circulate coolant through the traction battery; a cabin heating circuit configured to circulate coolant through the heater and the heater core; a blower configured to circulate air through the heater core to heat a passenger compartment of the vehicle; and a valve configured to fluidly connect the battery circuit and the heating circuit when the valve is in a first position and configured to fluidly isolate the battery circuit from the heating circuit when the valve is in a second position. A controller is programmed to, in response to (i) the battery being charged, (ii) a temperature of the battery being less than a first threshold, and (iii) a temperature of the heater core being greater than a second threshold, energize the heater and command the valve to continuously switch between the first position and the second position, heat generated by the heater is circulated to the battery and the heater core.

Description

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 606,421, filed on December 5, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] The present disclosure relates to automotive climate systems. Background Art

[0003] A high voltage battery in a hybrid or pure electric vehicle may have a thermal range for operation. If the battery cells are cooler than that range, the discharge power may be lower. A cold battery may also store less energy. Summary of the invention

[0004] According to one embodiment, a vehicle includes a traction battery and a motor powered by the traction battery and configured to provide power to wheels of the vehicle. The vehicle also includes a thermal management system having: a battery circuit configured to circulate coolant through the traction battery; a cabin heating circuit configured to circulate coolant through a heater and a heater core; a blower configured to circulate air through the heater core to heat a passenger cabin of the vehicle; and a valve configured to fluidly connect the battery circuit and the heating circuit when the valve is in a first position and to fluidly isolate the battery circuit from the heating circuit when the valve is in a second position. A controller is programmed to energize the heater and command the valve to continuously switch between the first position and the second position in response to (i) the battery being charged, (ii) the temperature of the battery being less than a first threshold, and (iii) the temperature of the heater core being greater than a second threshold, so that heat generated by the heater is circulated to the battery and the heater core.

[0005] According to another embodiment, a vehicle includes an electric powertrain having a traction battery and an electric motor powered by the traction battery. A controller is programmed to, in response to a temperature of the battery being less than a threshold temperature and an estimated range to empty being greater than a threshold distance, command powering the electric motor according to an inefficient heat generating mode that generates more heat from the battery and the electric motor than a high efficiency normal mode of operating the battery and the electric motor.

[0006] According to yet another embodiment, a method for heating a vehicle battery includes, in response to a temperature of the battery being less than a threshold temperature and an estimated remaining energy range being greater than a threshold distance, switching from a high-efficiency normal operating mode to a low-efficiency heat-generating mode such that, for a given power output, the battery generates more heat than in the normal operating mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic diagram of an exemplary electric vehicle.

[0008] Figure 2 is a schematic diagram of the vehicle's thermal management system.

[0009] FIG. 3A to FIG. 3B is a flow chart of an algorithm for operating a thermal management system during battery charging.

[0010] FIG. 4A to FIG. 4C is a control diagram showing the logic for switching between different battery heating modes. DETAILED DESCRIPTION

[0011] Embodiments are described herein. However, it should be understood that the disclosed embodiments are merely examples and that other embodiments may take various and alternative forms. The drawings are not necessarily drawn to scale. Some features may be enlarged or minimized to show details of particular components. Therefore, the specific structural details and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art.

[0012] The various features shown and described with reference to any one of the accompanying drawings may be combined with features shown in one or more other drawings to produce embodiments not explicitly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, for specific applications or implementations, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired.

[0013] In some cases, actively heating the battery can increase the available driving range. By heating the high-voltage battery, the vehicle's driving range can be extended and the vehicle's acceleration performance can be improved.

[0014] As will be described in more detail below, the vehicle's thermal system assesses the need for active battery thermal management based on battery cell temperature and state of charge. If battery heating is required, cabin heating is checked. If cabin heating is off, battery heating is enabled. If cabin heating is on but the vehicle has just been started and the cabin is currently cold, some heat is transferred to the high voltage battery for a short amount of time to warm the battery while slightly delaying cabin warm-up. If cabin heating is required but the vehicle has not been started recently, plug status is checked. If the vehicle is DC charging, only blower speed is checked to determine if heating should be shared with the cabin or battery heating should be prioritized.

[0015] If the vehicle is not DC charging, additional thresholds are checked to determine if there is excess heat capacity in the vehicle thermal system. These thresholds may include ambient temperature, climate defrost status, climate performance, and heater duty cycle. If there is excess heat capacity, the heat is shared by both the cabin and the high voltage battery by moving a valve to distribute warm coolant between the heater core and the battery heat exchanger.

[0016] The valve is manipulated based on the heater core temperature compared to the heater core temperature target. In some cases, it may be possible to maintain the heater core temperature while still heating the high voltage battery. In other cases, the valve will switch between sharing heat with the high voltage battery and dedicating heat to the heater core based on a calibrated timer table.

[0017] Heat sharing will continue until the high voltage battery temperature target is reached, or if there is no more excess heat, such as if the customer increases the cabin heating target or enables defrost mode.

[0018] The above can allow for active heating of the battery when the vehicle is not charging, as well as balancing the heat distribution between the cabin and the battery by moving the valve to maintain acceptable cabin thermal performance while still providing some heat to the high voltage battery for warming. There is also an extended entry threshold to determine excess thermal capacity in the system.

[0019] The algorithms, methods or processes disclosed herein may be transmitted to or implemented by a computer, a controller or a processing device, which may include any dedicated electronic control unit or a programmable electronic control unit. Similarly, the algorithms, methods or processes may be stored in various forms as data and instructions executable by a computer or controller, including but not limited to information permanently stored on a non-writable storage medium such as a read-only memory device and information that can be modified and stored on a writable storage medium such as an optical disk, a random access memory device or other magnetic and optical media. Algorithms, methods or processes may also be implemented as software executable objects. Alternatively, suitable hardware components (such as application specific integrated circuits, field programmable gate arrays, state machines or other hardware components or devices) or a combination of firmware, hardware and software components may be used to embody the algorithm, method or process in whole or in part.

[0020] Figure 1 A schematic diagram of a battery electric vehicle (BEV) is depicted. However, certain embodiments may also be implemented in the context of a plug-in hybrid vehicle. Vehicle 12 includes one or more electric machines (traction motors) 14 that are mechanically connected to a transmission or gearbox 16. Gearbox 16 may be a single speed gearbox and may include a differential. Gearbox 16 is operably coupled to driven wheels of vehicle 22 via axle shafts 20.

[0021] Traction battery or battery pack 24 stores energy that may be used by electric machine 14. Traction battery 24 generally provides a high voltage direct current (DC) output from one or more battery cell arrays (sometimes referred to as battery cell stacks) within traction battery 24. A battery cell array may include one or more battery cells.

[0022] Battery cells (such as square, pouch, cylindrical, or any other type of cell) convert stored chemical energy into electrical energy. A battery cell 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 back during recharge. Terminals may allow current to flow out of the battery cell for use by the vehicle. Different battery pack configurations may be used to meet individual vehicle variables, including packaging constraints and power requirements. A thermal management system may be used to thermally regulate the battery cells. Examples of thermal management systems include liquid cooling systems.

[0023] The traction battery 24 may be electrically connected to one or more power electronics modules 26 via one or more contactors (not shown). The one or more contactors isolate the traction battery 24 from other components when open and connect the traction battery 24 to other components when closed. The power electronics module 26 may be electrically connected to the motor 14 and may provide the ability to transfer electrical energy bidirectionally between the traction battery 24 and the motor 14. For example, a typical traction battery 24 may provide a DC voltage, while the motor 14 may require a three-phase alternating current (AC) voltage to function. The power electronics module 26 may convert the DC voltage to a three-phase AC voltage according to the requirements of the motor 14. In the regenerative mode, the power electronics module 26 may convert the three-phase AC voltage from the motor 14 acting as a generator to the DC voltage required by the traction battery 24.

[0024] In addition to providing energy for propulsion, the traction battery 24 can also 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 into a low voltage DC supply that is compatible with other vehicle components. Other high voltage loads (such as compressors, pumps, and electric heaters) may be connected directly to the high voltage supply without using the DC / DC converter module 28. In a typical vehicle, the low voltage systems are electrically connected to the auxiliary battery 30 ( For example , 12 volt battery).

[0025] A battery energy control module (BECM) 33 may communicate 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 the temperature and state of charge of each of the battery cells. The traction battery 24 may have a temperature sensor 31, such as a thermistor or other temperature sensor. The temperature sensor 31 may communicate with the BECM 33 to provide temperature data about the power battery 24.

[0026] The vehicle 12 can be recharged by a charging station connected to an external power source 36. The external power source 36 can be electrically connected to an electric vehicle supply equipment (EVSE) 38. The external power source 36 can provide DC and / or AC power to the EVSE 38. The EVSE 38 can have a charging connector 40 for plugging into a charging port 34 of the vehicle 12. The charging port 34 can be any type of port configured to transfer power from the EVSE 38 to the vehicle 12. The charging port 34 can be electrically connected to one or more chargers or on-board power conversion modules 32. The charging port 34 can include a connector for AC charging and another connector for DC charging. The power conversion module 32 can regulate the power supplied from the EVSE 38 to provide the appropriate voltage and current levels to the traction battery 24. The power conversion module 32 can be connected to the EVSE 38 to coordinate the power delivery to the vehicle 12. The EVSE connector 40 can have pins that mate with corresponding pins of the charging port 34. The charging port 34 and the vehicle 12 may be configured to connect to a so-called “fast charge” charging station. During fast charging, the vehicle may receive a high voltage DC current.

[0027] The various components discussed may have one or more controllers to control and monitor the operation of the components. The controllers may communicate with each other via a serial bus ( For example , Controller Area Network (CAN)) or via dedicated electrical conduits. The controller typically includes any number of microprocessors, ASICs, ICs, memory ( For example , flash memory, ROM, RAM, EPROM and / or EEPROM) and software code to work together to perform a series of operations. The controller also includes predetermined data or "lookup tables" based on calculations and test data and stored in the memory. The controller can use a common bus protocol ( For example , CAN and LIN) and communicate with other vehicle systems and controllers through one or more wired or wireless vehicle connections. Any reference to "controller" used herein refers to one or more controllers.

[0028] The traction battery 24 and other vehicle components are thermally regulated using one or more thermal management systems. Example thermal management systems are shown in the accompanying figures and described below.

[0029] refer to Figure 2 , the vehicle 12 includes a thermal management system 56. The thermal management system 56 manages the heat loads generated by various vehicle components such as the battery assembly 24, powertrain components, power electronics components 25, and the passenger compartment. For example, the thermal management system 56 can selectively circulate a coolant to the battery 24 to cool or heat the battery depending on operating conditions.

[0030] The thermal management system 56 may include one or more associated vehicle controllers 78. The controller 78 may be part of a larger control system and may be controlled by various other controllers throughout the vehicle, such as a vehicle system controller (VSC), including a powertrain control unit, a transmission control unit, an engine control unit, a battery energy control module (BECM), a hybrid powertrain control model (HPCM), etc. It should be understood that the controller 78 and one or more other controllers may be collectively referred to as "controllers" that control various actuators in response to signals from various sensors, such as through a variety of integrated algorithms, to control functions associated with the vehicle (and in this case, the thermal management system 56). The various controllers that make up the VSC may use a common bus protocol ( For example , CAN) to communicate with each other.

[0031] In one embodiment, the thermal management system 56 includes a coolant subsystem 58 and a refrigerant (heat pump) subsystem 60. The two circuits can be operated in series or independently of each other depending on battery cooling / heating requirements, ambient air temperature, passenger cooling / heating requirements, and other factors. The refrigerant subsystem 60 can be a vapor compression heat pump that circulates the refrigerant to transfer thermal energy to various components of the thermal management system. The refrigerant subsystem 60 can include an air conditioning (AC) system for the cabin and a cooling system for the battery 24. It may be more cost-effective to utilize the cabin AC than to have a dedicated refrigerant system for the traction battery 24. The coolant subsystem 58 includes a battery circuit 59 and a cabin heating circuit 61. The battery circuit 59 circulates the coolant through the battery assembly 24. The battery circuit 59 can be connected to the power electronics circuit 63 through a valve 67. The valve 67 includes a first position in which the battery circuit 59 is isolated from the power electronics circuit 63 and a second position in which the battery circuit 59 is connected to the power electronics circuit. In the illustrated embodiment, the radiator 71 is part of the loop 63, however, in other embodiments, the radiator 71 can be part of the battery loop 59, or alternatively, both loops can include their own radiators. The coolant can be a conventional coolant mixture, such as a mixture of water with ethylene glycol or other antifreeze. The coolant subsystem 58 can also use other coolants.

[0032] The battery loop 59 includes conduits, lines, hoses, or pipes 70 configured to circulate a coolant through the battery 24 and a cooler 76. The coolant may be circulated by a pump 68. The battery loop 59 may also include a temperature sensor 69 upstream of the battery 24 and configured to output data indicative of a measured temperature of the coolant to a controller 78. A bypass valve 66 may be provided to bypass the cooler 76.

[0033] The cooler 76 exchanges heat with the refrigerant subsystem 60 during certain conditions to provide cooled coolant. For example, when the battery temperature exceeds a predefined threshold and the cabin AC system 60 has capacity, the valve 66 can be actuated to circulate at least some coolant to the cooler 76. Warm coolant from the battery pack 24 can enter the cooler 76 and exchange heat with the refrigerant of the refrigerant subsystem 60 to dissipate heat. The battery cooler 76 can have any suitable configuration. For example, the cooler 76 can have a plate-fin, tube-fin, or shell-and-tube configuration that facilitates the transfer of thermal energy without mixing the heat transfer fluids in the coolant subsystem 58 and the refrigerant subsystem 60.

[0034] The refrigerant subsystem 60 may include a compressor, a condenser, at least one cabin evaporator, a cooler, a first expansion device, a shutoff valve, a second expansion device, and a second shutoff valve. The compressor pressurizes the refrigerant and circulates the refrigerant through the refrigerant subsystem 60. The compressor may be powered by an electrical source or a non-electrical source. A pressure sensor may monitor the pressure of the refrigerant leaving the compressor.

[0035] The refrigerant leaving the compressor may be circulated through one or more conduits to a condenser. The condenser transfers heat to the surrounding environment by condensing the refrigerant from a vapor to a liquid. A fan may be selectively actuated to circulate the airflow through the condenser, thereby further achieving heat transfer between the refrigerant and the airflow.

[0036] At least a portion of the liquid refrigerant leaving the condenser can be circulated through a first expansion device (depending on the position of the valve) and then to the evaporator. The first expansion device is suitable for changing the pressure of the refrigerant. In one embodiment, the first expansion device is an electronically controlled expansion valve (EXV). In another embodiment, the first expansion device is a thermal expansion valve (TXV) or a passive device. If the expansion device is an EXV, the shut-off valve can be omitted. The liquid refrigerant evaporates from liquid to gas while absorbing heat in the evaporator. The gaseous refrigerant can then return to the compressor. The refrigerant subsystem can include an evaporator temperature sensor electrically connected to the controller 78. The sensor outputs a signal indicating the evaporator temperature. The controller 78 can operate the system based on the signal received from the sensor. Alternatively, the valve can be closed to bypass the evaporator.

[0037] Another portion of the liquid refrigerant leaving the condenser (or all of the refrigerant if the valve is closed) can circulate through the second expansion device and enter the chiller 76 if the valve is open. The second expansion device (which can also be an EXV or TXV or a passive device) is adapted to change the pressure of the refrigerant. The refrigerant exchanges heat with the coolant in the chiller 76 to provide cooled coolant to the battery 24 during the chiller mode.

[0038] The cabin heating circuit 61 may include a pump 100, a heater 102, a heater core 104, and a conduit 106. The conduit is configured to circulate the coolant through various components of the heating circuit 61. A temperature sensor 105 may be disposed on the conduit 106 downstream of the heater 102 and upstream of the heater core 104. The temperature sensor 105 is electrically connected to the controller 78 and is configured to output data indicating the measured temperature of the coolant. The heater 102 may be an electric heater powered by a battery pack 24 or other source. In one or more embodiments, the heater 102 is a PTC heater. The heater core 104 may be disposed in an HVAC unit of the vehicle 12. Typically, the HVAC unit is disposed below the dashboard in the passenger compartment. The heater core 104 is a liquid-to-air heat exchanger that transfers heat energy from the coolant to an airflow driven by a fan 108. The airflow generated by the fan 108 is directed into the passenger compartment to provide heat.

[0039] The thermal management system 56 may include only one heater 102 shared between the passenger cabin and the traction battery 24. The valve 110 selectively connects the battery circuit 59 and the cabin heating circuit 61 in fluid communication. The valve 110 may be an electronically controlled valve, such as a four-way valve. The valve includes at least one position (a first position) in which the battery circuit 59 and the cabin heating circuit 61 are connected in fluid communication and a position (a second position) in which the fluid communication between the battery circuit 59 and the cabin heating circuit 61 is cut off. Right now , the circuits 59 and 61 are isolated from each other). Figure 2 In FIG. 1 , the first position is shown in solid lines, while the second position is shown in dashed lines.

[0040] The valve 110 may include four ports or fittings 112, 114, 116, and 118. Ports 112 and 118 are connected to conduits of the battery circuit 59. Ports 114 and 116 are connected to conduits of the cabin heating circuit 61. Port 112 may be an inlet port for the battery circuit 59, and port 116 may be an inlet port for the cabin heating circuit 61. Port 118 may be an outlet port for the battery circuit 59, and port 114 may be an outlet port for the cabin heating circuit 61. In a first position, ports 112 and 114 are connected in fluid communication, and ports 116 and 118 are connected in fluid communication (the battery and the heater core are in fluid communication). In a second position, ports 112 and 118 are connected in fluid communication, and ports 114 and 116 are connected in fluid communication (the battery is independent of the heater core).

[0041] Because the heater 102 is shared between the battery 24 and the passenger cabin, the sum of the heat requested by the passenger cabin and the traction battery may exceed the heating capacity of the heater 102. That is, there is not enough thermal energy to provide the requested heating at the same time. In these cases, the thermal management system 56 must prioritize between the passenger cabin and the battery, or provide a lesser amount of heating to both systems.

[0042] FIG. 3A to FIG. 3B A flow chart 200 of an algorithm for controlling the thermal management system 56 is shown. Control begins at operation 302 where the controller compares the battery temperature, which may be measured by the battery temperature sensor 125, to a heating threshold. The heating threshold indicates whether the battery would benefit from heating. An exemplary temperature is 70 degrees Fahrenheit, but this will vary depending on the battery pack. If the battery temperature is above the threshold, control 300 is exited.

[0043] In operation 304, the controller determines whether the vehicle is key-off. If the key is off, control passes to operation 306, and the controller determines the plug status of the vehicle, Right now , whether the vehicle is plugged into the charging station. If the vehicle is plugged in, control passes to operation 308, and the controller determines whether the plug power is greater than a threshold. If so, control passes to operation 310, and the controller requests battery heating.

[0044] At operation 312, the controller determines whether the state of charge of the battery is greater than a threshold value (the threshold value is based on the battery temperature), the discharge power is less than a calibrated value, and the battery temperature is less than a calibrated value. If so, at operation 314, the vehicle prioritizes heating the battery and actuates valve 110 to promote battery heating rather than cabin heating. If not, at operation 316, the vehicle prioritizes heating the passenger cabin and actuates valve 110 to promote cabin heating rather than the battery.

[0045] If the vehicle is key-on, the controller determines whether the vehicle is actively undergoing DC fast charging or whether the power pack is on. At operation 322, the controller determines whether the battery temperature is less than a lower threshold. The lower threshold indicates whether there is any urgency to heat the battery. (The lower threshold does not indicate the power limit temperature of the battery; it will be referred to as the "minimum threshold" later.) Although exemplary embodiments are described above, these embodiments are not intended to describe all possible forms encompassed. The words used in the specification are words of description rather than limitation, and it should be understood that various changes can be made without departing from the spirit and scope of these disclosed materials. The lower threshold is dynamic and based on vehicle conditions. For example, the change in the lower threshold can be based on the plug charger power ( For example, if 20 kw, the threshold is 10℃, and if 150 kw, the threshold is 25℃), whether the vehicle is on the way to a charging station, and the SOC of the battery ( For example , if low SOC, the threshold is 5° C.; if medium SOC, the threshold is −5° C.; and if high SOC, the threshold is −20° C.). Of course, these are non-limiting examples.

[0046] If the battery temperature is greater than the lower threshold, passive heating is used to warm the battery at operation 324. Passive heating may refer to heating the battery using waste heat generated by the battery, the motor, or any other component of the electric powertrain that is in fluid communication with the battery. As will also be explained in more detail below, the electrical components of the electric powertrain may be operated in an inefficient mode to generate additional waste heat. This may occur within the passive heating of operation 324, depending on the sensed conditions, as will be explained below.

[0047] If the battery temperature is less than the lower threshold, control passes to a series of operations 326 to 332 that identify whether the battery can be actively heated. In operation 326, the controller determines that the vehicle is being actively charged. In operation 328, the controller determines whether the battery has sufficient SOC to travel to a charging station. The battery SOC can be converted to a distance, called Remaining energy for driving distance . The controller may compare the remaining energy drivable distance to a threshold difference. If yes, this indicates that the battery SOC is sufficient to travel to a charging station. If no, this indicates that the battery SOC is insufficient to travel to a charging station. At operation 330, the controller determines whether there is valid route guidance to the charging station. For example, the driver selects a charging station within the vehicle navigation, which then generates a route to prompt the driver with driving directions to the charging station, or in the case of an autonomous vehicle, to drive the vehicle to the charging station. At operation 332, the controller determines whether the battery is power limited due to temperature. For example, the controller may compare the temperature of the battery to a minimum threshold temperature.

[0048] If either of these operations is no, the controller uses passive heating.

[0049] If any of these operations are yes, control passes to operation 334. In operation 334, the controller can check three conditions. The first condition is whether the heater core temperature is greater than a threshold when the key is turned on. The second condition is whether the HVAC is in defrost (DEFROST). The third condition is whether the fan speed of the HVAC is less than a threshold. If these conditions are met, control passes to operation 336.

[0050] At operation 336, the controller initiates a cold heater core strategy. Since the cabin is cold when the key is turned on, the driver will not expect immediate heating. Thus, battery heating can be prioritized for at least a period of time. In one embodiment, the valve can be controlled so that the battery receives all heat for an initial duration when the cold heater core strategy begins. After the expiration of this time, the valve can be commanded to a shared position in which the battery and heater core receive heat for a second duration. Expiration of the second duration can initiate cabin priority heating. The customer can override this battery priority by increasing the blower speed or similar manipulation of the HVAC controls.

[0051] If no at operation 334, control passes to operation 338 where the controller determines if the fan speed is less than a threshold or if high battery priority heating is active. If no, control passes to operation 340 and the valve is actuated to disconnect the cabin circuit from the battery circuit so that all heat generated by the heater is circulated to the passenger compartment. The battery will then be passively heated using either the normal mode or the heat generating mode as described below with reference to FIG. 4A to FIG. 4C described.

[0052] If yes at operation 338, control passes to operation 342 where the controller determines whether the vehicle is currently charging, Right now , inserted into the charging station. If so, shared heating is activated by energizing the heater and actuating the valve to a shared position where the battery circuit and the cabin circuit are connected to include communication. Depending on the sensed conditions, switching of the valve may or may not occur during shared heating. Switching refers to the relatively rapid and continuous transformation of the valve between a position where the cabin circuit and the battery circuit are fluidly connected and another position where the cabin circuit and the battery circuit are not fluidly connected (cut off). The frequency of switching is based on sensed conditions, such as ambient temperature, battery temperature, HVAC set point, and passenger compartment temperature. In some embodiments, and based on the sensed conditions, the valve may switch between valve positions at least 2 times per minute. In other embodiments, and based on the sensed conditions, the valve may switch between any valve positions 3 to 50 times per minute. In other embodiments, and based on the sensed conditions, the valve may switch between any valve positions 2 to 50 times every 10 minutes. In one or more embodiments, the controller may switch the valve during operation 144 when the ambient temperature is less than a threshold, and may not switch the valve when the ambient temperature is greater than a threshold. The switching results in the passenger compartment receiving more heat than in a constant shared position of the valve.

[0053] If no at operation 342, control passes to operation 346, where the controller determines whether the battery is power limited. The vehicle can determine whether the battery is power limited by monitoring the discharge power of the battery. If the discharge power is low, this means that the battery may not have enough power to provide the torque requested by the driver.

[0054] If so, control passes to operation 348 and the controller activates a high priority battery heating mode. In this mode, the battery takes precedence over the cabin. However, this does not necessarily mean that the cabin does not receive heat. Depending on the sensed conditions, the cabin may receive some heat as long as there is still enough heat for the battery. In one or more embodiments, the high priority battery heating mode may employ switching to provide an appropriate balance between battery heating and cabin heating. In other embodiments, or under other sensed conditions, switching may not occur. In some embodiments, or alternatively, under some sensed conditions, the fan speed associated with the HVAC fan may be reduced to low to provide some cabin heating, while most of the heating is directed to the traction battery.

[0055] In operation 350, the controller determines whether the ambient temperature is above a threshold. If so, control passes to operation 352, and the controller determines whether the driver has requested cabin defrost. If not, control passes to operation 354, and the controller determines whether the heater core delta is less than a threshold. If so, control passes to operation 356, and the controller determines whether the shared cabin heating capacity is greater than a threshold, i.e., whether there will be any heat left for the battery after the cabin demand is met. If so, control passes to operation 358 and the shared heating mode is activated. At operation 358, the valve is actuated so that heat from the heater can be directed to the battery and the cabin. In some embodiments, the valve can be switched as described above.

[0056] If the conditions for shared heating are not met, control passes to operation 360 where the valve is actuated for cabin heating only. At operation 360 , all heat energized by the heater is circulated to the heater core and waste heat generated by one or more components of the electric powertrain is used to heat the battery.

[0057] As described above, in some cases, waste heat generated by one or more components of the electric powertrain is used to heat the battery. This can be referred to as passive heating. During passive heating, one or more components of the electric powertrain may be operated inefficiently so as to generate more waste heat than would otherwise occur. That is, the vehicle can be commanded to be powered from the electric powertrain in a normal high-efficiency mode and an inefficient heat-generating mode that generates more heat than in normal mode. For example, power electronics, batteries, motors, etc. can be operated so that for a given power input or output, more heat is generated than in normal mode. In one example, for a given power output, the battery generates more heat in heat-generating mode than in normal mode. In another example, for a given power input, the power electronics convert more input into heat when in heat-generating mode than in normal mode. Of course, these are just examples, and excess heat can be generated in heat-generating mode in other ways.

[0058] FIG. 4A to FIG. 4C Logic for switching between a shared heating mode 400 , a passive heating mode 402 in which electric powertrain components operate normally, and a passive heating mode 404 in which one or more components of the electric powertrain operate in a heat generating mode is schematically illustrated.

[0059] The controller may consider a number of factors to determine whether to use normal mode or heat generating mode for passive heating. For example, the controller may command that the motor be powered according to a heat generating mode that operates inefficiently to generate additional heat from the battery and the motor in response to (i) the temperature of the battery is less than a threshold temperature, (ii) effective route guidance to a charging station, and (iii) an estimated remaining energy range is greater than a threshold distance. The controller may command that the motor be powered according to a normal mode in response to (i) the temperature of the battery is less than a threshold temperature, (ii) effective route guidance to a charging station, and (iii) an estimated remaining energy range is greater than a threshold distance.

[0060] The controller may be further programmed to command the motor to be powered according to the heat generation mode in response to (i) the temperature of the battery is less than a threshold temperature and the state of charge of the battery is greater than a threshold. The controller may be further programmed to command the motor to be powered according to the normal mode in response to (i) the temperature of the battery is less than a threshold temperature and the state of charge of the battery is less than a threshold.

[0061] like FIG. 4A to FIG. 4CAs further shown in FIG. 4 , additional condition changes may result in a change from passive heating of the battery to active heating in shared mode 400. For example, shared heating may be commanded based on HVAC fan speed, state of charge, ambient temperature, whether cabin defrost is on or off, whether the heater core temperature delta is less than a threshold, and an estimated shared heating capacity. In one example, shared heating will be commanded if the fan speed is less than a threshold and the battery is charging. In another example, shared heating will be commanded if the fan speed is less than a threshold, the ambient temperature is greater than a threshold, the defrost is off, the heater core temperature delta is less than a threshold, the shared heating capacity is greater than a minimum calibration, and the shared heating capacity is greater than the waste heat generated by the electric powertrain.

[0062] As previously described, features of the various embodiments may be combined to form additional embodiments of the invention that may not be explicitly described or shown. Although various embodiments may have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, it will be appreciated by those of ordinary skill in the art that one or more features or characteristics may be compromised to achieve desired overall system properties, depending on the specific application and implementation. These properties may include, but are not limited to, strength, durability, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, and the like. For this reason, embodiments described as being less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of this disclosure and may be desirable for specific applications.

[0063] According to the present invention, a vehicle is provided, having: a traction battery; an electric motor powered by the traction battery and configured to provide power to wheels of the vehicle; a thermal management system including: a battery circuit configured to circulate a coolant through the traction battery; a cabin heating circuit configured to circulate a coolant through a heater and a heater core; a blower configured to circulate air through the heater core to heat a passenger cabin of the vehicle; and a valve configured to fluidly connect the battery circuit and the heating circuit when the valve is in a first position and to fluidly isolate the battery circuit from the heating circuit when the valve is in a second position; and a controller programmed to energize the heater and command the valve to continuously switch between the first position and the second position in response to (i) the battery being charged, (ii) the temperature of the battery being less than a first threshold, and (iii) the temperature of the heater core being greater than a second threshold, so that heat generated by the heater is circulated to the battery and the heater core.

[0064] According to one embodiment, the valve switches between the first position and the second position such that the valve changes between the first position and the second position at least twice per minute.

[0065] According to one embodiment, the controller is further programmed to reduce the blower speed in response to (i) the battery being charged, (ii) the temperature of the battery being less than the first threshold, and (iii) the temperature of the heater core being less than the second threshold.

[0066] According to one embodiment, the first threshold is a dynamic value.

[0067] According to one embodiment, the first threshold is based on the state of charge of the battery.

[0068] According to one embodiment, the controller is further programmed to end the switching and actuate the valve to the first position in response to the temperature of the battery exceeding a third threshold.

[0069] According to one embodiment, the present invention is further characterized by: a power electronics module; and a second valve that selectively connects the battery and the power electronics module in fluid communication.

[0070] According to the present invention, a vehicle is provided, the vehicle having: an electric powertrain including a traction battery and an electric motor powered by the traction battery; and a controller programmed to, in response to a temperature of the battery being less than a threshold temperature and an estimated remaining energy range being greater than a threshold range, command powering the electric motor according to an inefficient heat generation mode that generates more heat from the battery and the electric motor than a high-efficiency normal mode of operating the battery and the electric motor.

[0071] According to one embodiment, the controller is further programmed to command powering of the electric machine according to the normal mode in response to the temperature of the battery being less than the threshold temperature and the estimated range to empty being less than the threshold distance.

[0072] According to one embodiment, the controller is further programmed to command powering of the motor according to the heat generating mode in response to (i) the temperature of the battery being less than the threshold temperature and the state of charge of the battery being greater than a threshold.

[0073] According to one embodiment, the temperature threshold is a dynamic value.

[0074] According to one embodiment, the temperature threshold is based on the state of charge of the battery.

[0075] According to one embodiment, the controller is further programmed to command powering of the motor according to the heat generating mode in response to (i) the temperature of the battery being less than the threshold temperature and the state of charge of the battery being greater than a threshold.

[0076] According to one embodiment, the controller is further programmed to command powering of the motor according to the normal mode in response to (i) the temperature of the battery being less than the threshold temperature and the state of charge of the battery being less than a threshold.

[0077] According to one embodiment, the present invention is further characterized by: a battery heating circuit, which is configured to circulate coolant through the battery; a vehicle cabin heating circuit, which is configured to circulate coolant through a heater core; and a valve, which is configured to fluidly connect the battery circuit and the heating circuit when the valve is in a first position and is configured to fluidly isolate the battery circuit and the heating circuit when the valve is in a second position.

[0078] According to one embodiment, the controller is also programmed to, in response to the temperature of the battery being less than the threshold temperature and requesting cabin heating: command the valve to the first position when the estimated heating capacity exceeds a third threshold, and command the valve to the second position when the estimated heating capacity is less than the third threshold.

[0079] According to one embodiment, the controller is further programmed to, in response to requesting cabin heating and the battery being power limited due to low temperature, command the valve to continuously switch between the first position and the second position such that heat generated by the heater circulates to the battery and the heater core.

[0080] According to one embodiment, the valve switches between the first position and the second position such that the valve changes between the first position and the second position at least twice per minute.

[0081] According to the present invention, a method for heating a vehicle battery includes: in response to a temperature of the battery being less than a threshold temperature and an estimated remaining energy range being greater than a threshold distance, switching from a high-efficiency normal operating mode to a low-efficiency heat-generating mode so that for a given power output, the battery generates more heat than in the normal operating mode.

[0082] In one aspect of the present invention, the method includes: in response to the temperature of the battery being less than the threshold temperature and the estimated remaining energy range being less than the threshold distance, switching from the heat generating mode to the normal mode so that for a given power output, the battery generates less heat than in the heat generating mode.

Claims

1. A vehicle comprising: Traction batteries; an electric motor powered by the traction battery and configured to provide power to wheels of the vehicle; A thermal management system, the thermal management system comprising: a battery circuit configured to circulate a coolant through the traction battery, a cabin heating circuit configured to circulate a coolant through a heater and a heater core, a blower configured to circulate air through the heater core to heat a passenger compartment of the vehicle, and a valve configured to fluidly connect the battery circuit and the heating circuit when the valve is in a first position and configured to fluidly isolate the battery circuit from the heating circuit when the valve is in a second position; as well as A controller is programmed to energize the heater and command the valve to continuously switch between the first position and the second position in response to (i) the battery is charging, (ii) the temperature of the battery is less than a first threshold, and (iii) the temperature of the heater core is greater than a second threshold, so that heat generated by the heater is circulated to the battery and the heater core. 2 . The vehicle of claim 1 , wherein the valve switches between the first position and the second position such that the valve switches between the first position and the second position at least twice per minute.

3. The vehicle of claim 1 wherein the controller is further programmed to reduce the blower speed in response to (i) the battery being charged, (ii) the temperature of the battery being less than the first threshold, and (iii) the temperature of the heater core being less than the second threshold. The vehicle of claim 1 , wherein the first threshold is a dynamic value.

5. The vehicle of claim 4, wherein the first threshold is based on a state of charge of the battery.

6. The vehicle of claim 1 wherein the controller is further programmed to terminate the switching and actuate the valve to the first position in response to the temperature of the battery exceeding a third threshold.

7. The vehicle of claim 1, further comprising: Power electronics modules; as well as A second valve selectively connects the battery and the power electronics module in fluid communication.

8. A vehicle comprising: an electric powertrain including a traction battery and an electric machine powered by the traction battery; as well as a controller programmed to, in response to a temperature of the battery being less than a threshold temperature and an estimated range to empty being greater than a threshold distance, command powering the electric motor according to an inefficient heat generating mode that generates more heat from the battery and the electric motor than a high efficiency normal mode of operating the battery and the electric motor.

9. The vehicle of claim 8, wherein the controller is further programmed to command powering of the electric motor according to the normal mode in response to the temperature of the battery being less than the threshold temperature and the estimated range to empty being less than the threshold distance.

10. The vehicle of claim 9, wherein the controller is further programmed to command powering of the electric machine according to the heat generating mode in response to (i) the temperature of the battery being less than the threshold temperature and the state of charge of the battery being greater than a threshold.

11. The vehicle of claim 8, wherein the temperature threshold is a dynamic value.

12. The vehicle of claim 11, wherein the temperature threshold is based on a state of charge of the battery.

13. The vehicle of claim 8, wherein the controller is further programmed to command powering of the motor according to the heat generating mode in response to (i) the temperature of the battery being less than the threshold temperature and the state of charge of the battery being greater than a threshold.

14. The vehicle of claim 13, wherein the controller is further programmed to command powering of the electric machine according to the normal mode in response to (i) the temperature of the battery being less than the threshold temperature and the state of charge of the battery being less than a threshold.

15. A method of heating a vehicle battery, comprising: In response to a temperature of the battery being less than a threshold temperature and an estimated remaining energy range being greater than a threshold distance, a transition is made from a high-efficiency normal operating mode to a low-efficiency heat-generating mode such that, for a given power output, the battery generates more heat than in the normal operating mode.

Images