The present disclosure relates to a control strategy and method for preconditioning a traction battery and/or a passenger cabin of a motor vehicle.
The need to reduce fuel consumption and emissions in automobiles and other vehicles is well known. Vehicles are being developed that reduce reliance or completely eliminate reliance on internal combustion engines. Electrified vehicles are one type of vehicle currently being developed for this purpose. A major challenge with electric vehicles is increasing the fully-electric range of the vehicle.
According to one embodiment, a vehicle includes a traction battery, a cabin, and a controller. The controller is programmed to, in response to a request to heat both the battery and the cabin, and a time to next planned usage of the vehicle exceeding a first threshold time, heat the battery and delay heating the cabin at least until the time to next planned usage is less than the first threshold time.
According to another embodiment, a vehicle includes a battery, a thermal circuit, and a controller. The thermal circuit is arranged to circulate coolant through the battery, a heater, a pump and valving. The controller is programmed to, in response to a request to heat both the battery and a cabin, and a time to next planned usage of the vehicle exceeding a first threshold time, de-energize a cabin blower, energize the pump and the heater, and actuate the valving such that the battery receives heated coolant.
According to yet another embodiment, a method of preconditioning a vehicle is disclosed. The vehicle includes a cabin and a traction battery configured to receive power from a charging station. The method includes receiving a request to heat both the battery and the cabin. The method further includes heating the battery while the vehicle is receiving power from the charging station in response to a time to next planned usage of the vehicle being greater than a first threshold time. The method also includes delaying heating of the cabin at least until the time to next planned usage is less than the first threshold time.
Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
A fraction battery or battery pack 24 stores energy that can be used by the electric machines 14. The fraction battery 24 typically provides a high voltage direct current (DC) output from one or more battery cell arrays, sometimes referred to as battery cell stacks, within the traction battery 24. The battery cell arrays may include one or more battery cells.
The battery cells (such as a prismatic, pouch, cylindrical, or any other type of cell), convert stored chemical energy to electrical energy. The cells may include a housing, a positive electrode (cathode) and a negative electrode (anode). An electrolyte may allow ions to move between the anode and cathode during discharge, and then return during recharge. Terminals may allow current to flow out of the cell for use by the vehicle.
Different battery pack configurations are available to address individual vehicle variables including packaging constraints and power requirements. The battery cells may be thermally regulated with a thermal management system. Examples of thermal management systems include air cooling systems, liquid cooling systems, and a combination of air and liquid systems.
The traction battery 24 may be electrically connected to one or more power electronics modules 26 through one or more contactors (not shown). The one or more contactors isolate the traction battery 24 from other components when opened, and connect the traction battery 24 to other components when closed. The power electronics module 26 may be electrically connected to the electric machines 14 and may provide the ability to bi-directionally transfer electrical energy between the traction battery 24 and the electric machines 14. For example, a typical traction battery 24 may provide a DC voltage while the electric machines 14 may require a three-phase alternating current (AC) voltage to function. The power electronics module 26 may convert the DC voltage to a three-phase AC voltage as required by the electric machines 14. In a regenerative mode, the power electronics module 26 may convert the three-phase AC voltage from the electric machines 14 acting as generators to the DC voltage required by the traction battery 24.
In addition to providing energy for propulsion, the traction battery 24 may provide energy for other vehicle electrical systems. A typical system may include a DC/DC converter module 28 that converts the high voltage DC output of the traction battery 24 to a low voltage DC supply that is compatible with other vehicle components. Other high-voltage loads, such as air conditioning compressors and electric heaters, may be connected directly to the high-voltage supply without the use of a DC/DC converter module 28. In a typical vehicle, the low-voltage systems are electrically connected to the DC/DC converter and an auxiliary battery 30 (e.g., a 12 volt battery).
A battery energy control module (BECM) 33 may be in communication with the traction battery 24. The BECM 33 may act as a controller for the traction battery 24 and may also include an electronic monitoring system that manages temperature and charge state of each of the battery cells. The traction battery 24 may have a temperature sensor 31 such as a thermistor or other temperature gauge. The temperature sensor 31 may be in communication with the BECM 33 to provide temperature data regarding the traction battery 24.
The vehicle 12 may be recharged by an external power source 36. The external power source 36 may be a connection to an electrical outlet connected to the power grid or may be a local power source (e.g. solar power). The external power source 36 is electrically connected to a vehicle charging station 38. The charger 38 may provide circuitry and controls to regulate and manage the transfer of electrical energy between the power source 36 and the vehicle 12. The external power source 36 may provide DC or AC electric power to the charger 38. The charger 38 may have a charge connector 40 for plugging into a charge port 34 of the vehicle 12. The charge port 34 may be any type of port configured to transfer power from the charger 38 to the vehicle 12. The charge port 34 may be electrically connected to a charger or on-board power conversion module 32. The power conversion module 32 may condition the power supplied from the charger 38 to provide the proper voltage and current levels to the traction battery 24. The power conversion module 32 may interface with the charger 38 to coordinate the delivery of power to the vehicle 12. The charger connector 40 may have pins that mate with corresponding recesses of the charge port 34. In other embodiments, the charging station may be an induction charging station. Here, the vehicle may include a receiver that communicates with a transmitter of the charging station to wirelessly receive electric current.
The charging station 38 comes in various embodiments that have different power output capacities. For example, some stations 38 can output between 6 to 10 kilowatts (kW), while others can only output 1 to 2 kW. The power output of a charging station is dependent upon the voltage available and the current capacity of the circuitry.
The various components discussed may have one or more controllers to control and monitor the operation of the components. The controllers may communicate via a serial bus (e.g., Controller Area Network (CAN)) or via dedicated electrical conduits. The controller generally includes any number of microprocessors, ASICs, ICs, memory (e.g., FLASH, ROM, RAM, EPROM and/or EEPROM) and software code to co-act with one another to perform a series of operations. The controller also includes predetermined data, or “look up tables” that are based on calculations and test data, and are stored within the memory. The controller may communicate with other vehicle systems and controllers over one or more wired or wireless vehicle connections using common bus protocols (e.g., CAN and LIN). Used herein, a reference to “a controller” refers to one or more controllers.
The traction battery 24, the passenger cabin, and other vehicle components are thermally regulated with one or more thermal management systems. Example thermal management systems are shown in the Figures and described below. Referring to
The cabin loop 54 includes a heater core 58, an electric heater 60, a pump 62, a first valve 70, a sensor 72, and conduit forming a closed loop for circulating coolant, such as an ethylene glycol mixture. For example, coolant may be circulated from the pump 62 to the electric heater 60 via conduit 64. The electric heater 60 is connected to the heater core 58 via conduit 66. The heater core 58 is connected to pump 62 via conduit 68. The first valve 70 and the sensor 72 may be disposed on conduit 66. Alternately, conduit 66 may be separate conduits with one conduit connecting the heater 60 and the first valve 70, and another conduit connecting the first valve 70 and the heater core 58. The valve 70 may be a solenoid valve that is electronically controlled by the controller 51. Dashed lines illustrate electrical connections between the controller 51 and the various components. Solid lines illustrate coolant conduits.
The cabin loop 54 is configured to circulate heated coolant to the heater core 58 during at least a heating mode of the climate control system 50. The heater core 58 is disposed within the heating, ventilation, and air-conditioning (HVAC) housing 59. The electric heater 60 may be electrically connected to the traction battery 24, which provides power to the electric heater 60. The electric heater 60 may include a resistance heating element that converts electrical energy into heat energy in order to heat the coolant circulating through the heater 60. The fan 57 disposed within the HVAC housing 59 circulates air across the heater core 58 to extract heat from the coolant and blows the heated air into the cabin to heat the cabin. The sensor 72 measures a temperature of the coolant circulating in conduit 66 and sends a signal to the controller 51 that is indicative of the coolant temperature. Based on this temperature signal the controller may increase or decrease a heating output of the heater 60.
The battery thermal management system 52 may operate in a plurality of different modes, such as battery heating mode or battery cooling mode. The battery thermal management system 52 includes a battery coolant loop 74 that regulates the temperature of the traction battery 24. The battery loop 74 includes a battery radiator 76, a chiller 78, a pump 80, a second valve 82, a sensor 84, a third valve 86, and conduit arranged to circulate a coolant—such as an ethylene glycol mixture—between the various components of the battery cooling loop 74. For example, the pump 80 circulates coolant to the battery pack 24 via conduit 98. The sensor 84 may be disposed on conduit 98 up stream of the battery pack 24. The sensor 84 senses the temperature of the coolant and sends a signal indicative of the battery coolant temperature to the controller 51. Coolant exiting the battery pack 24 circulates to a four-way connector 100, and either circulates to the battery radiator 76 or to the chiller 78 depending upon the positioning of the valves 82, 86. The battery coolant loop 74 may cool the traction battery 24 via either the battery radiator 76 or the chiller 78. The chiller 78 dissipates heat by transferring thermal energy from coolant within the battery loop 74 to the refrigerant system 53. The battery radiator 76 is disposed behind a front grille of the vehicle and dissipates heat to the outside air. An inlet port of the battery radiator 76 is connected to the four-way connector 100 via conduit 96. An outlet port of the battery radiator 76 is connected to an inlet of the second valve 82 via conduit 94. An outlet of the second valve 82 is connected back to the pump 80 via conduit 98. Another inlet of the second valve 82 is connected to an outlet port of the chiller 78 via conduit 92. The second valve 82 may be similar to the first valve 70. The inlet port of the chiller 78 is connected to the third valve 86 via conduit 90. The third valve 86 may be similar to the first valve 70. The third valve 86 is connected to the four-way connector 100 via conduit 88. The third valve 86 may be connected to conduit 66 of the cabin loop 54 via a first interconnecting conduit 102. The four-way connector 100 may be connected to the first valve 70 of the cabin loop 54 via a second interconnecting conduit 104.
The battery loop 274 includes a battery radiator 276, a chiller 278, a pump 280, a second valve 282, a sensor 284, a third valve 286, and conduit arranged to circulate a coolant—such as an ethylene glycol mixture—between the various components of the battery cooling loop 274. For example, the pump 280 circulates coolant to the battery pack 224 via conduit 298. The sensor 284 may be disposed on conduit 298 upstream of the battery pack 224. Coolant exiting the battery pack 224 circulates to a four-way connector 200, and either circulates to the battery radiator 276 or the chiller 278 depending upon the positioning of the valves 270, 282, 286. The battery coolant loop 274 may cool the traction battery 224 via either the battery radiator 276 or via the chiller 278. The chiller 278 dissipates heat by transferring thermal energy from coolant within the battery loop 274 to the refrigerant system 253. The battery radiator 276 is disposed behind a front grille of the vehicle and dissipates heat to the outside air. An inlet port of the battery radiator 276 is connected to the four-way connector 200 via conduit 296. An outlet port of the battery radiator 276 is connected to an inlet of the second valve 282 via conduit 294. An outlet of the second valve 282 is connected back to the pump 280 via conduit 298. Another inlet of the second valve 282 is connected to an outlet port of the third valve 286 via conduit 293. An outlet port of the third valve 286 is connected to an outlet port of the chiller 278 via conduit 291. The inlet port of the chiller 278 is connected to the connector 200 via conduit 290. The third valve 286 may be connected to conduit 266 of the cabin loop 254 via a first interconnecting conduit 202. The four-way connector 200 may be connected to the first valve 270 of the cabin loop 254 via a second interconnecting conduit 204.
The range of an electric vehicle is at least partially dependent upon the amount of stored energy in the battery pack. Current battery technologies are limited in the amount of energy that can be stored within the battery pack. Vehicle range may be extended by using more battery energy for a vehicle propulsion and less battery energy for ancillary operations, such as heating the battery or cabin. One way to increase vehicle range is to precondition the vehicle prior to departure. During precondition, the vehicle is electrically connected with the charging station and wall power is available. Used herein, wall power refers to any external electrical power source, such as the power grid or a charging station. During precondition, the wall power is used to power the vehicle systems instead of the battery. The vehicle may be preconditioned by heating the battery, the cabin, or both via the wall power prior to departure. The controller 51 may receive input from a user stating the next departure time (or next planed usage time) or may estimate a departure time based on customer habits. Based on this departure time, the controller will begin preconditioning one or more of the vehicle systems at an appropriate time prior to departure. The preconditioning time varies according to the systems being preconditioned and the ambient conditions. For example, the battery requires a longer preconditioning time than the passenger cabin. As such, the controller will begin heating the battery prior to the cabin in the event both systems are requested to be heated. Also, the battery may require a longer preconditioning time when the air temperature is colder.
Preconditioning may be broken up into several different modes, such as battery heating mode, battery cooling mode, cabin cooling mode, and cabin heating mode. These modes may operate simultaneously or may operate one at a time depending upon vehicle conditions, time to next planned usage, and available wall power. Some of these modes will now be described below in detail.
Referring to
The controller 51 sends signals to the valves 70, 82, and 86 and in response the valves actuate into a desired position. For example, valve 70 may be actuated such that coolant exiting the heater 60 is circulated to the battery loop 74 via interconnecting conduit 102. Valve 86 is actuated such that coolant circulates to conduit 90 and not to conduit 88. Valve 82 is actuated such that coolant circulates to conduit 98 and not to conduit 94. The controller 51 may also send signals to the pump 62 and the pump 80 instructing the pumps to begin circulating coolant through the thermal circuit. The coolant is circulated through the heater 60 (where the coolant absorbs heat) and to the battery pack 24 via interconnecting conduit 102 and conduits 90, 92, and 98. The cells within the battery pack 24 absorb a portion of the thermal energy in the coolant as the coolant passes through the battery pack 24. The coolant then circulates back to the cabin loop 54 via interconnecting conduit 104. Valve 70 is actuated to direct coolant to the heater core 58. The fan 57 circulates air across the heater core 58 and blows warm air into the cabin. The coolant exiting the heater core 58 is then recirculated back to the pump 62 via conduit 68. During heating mode the controller monitors the various sensors (e.g. 72 and 84) and may adjusts a heating output of the heater 60 as desired. During a battery-only heating mode, the valves and pumps may be actuated the same as above, but the fan 57 is turned OFF. While this preconditioning mode is being described in conjunction with the embodiment shown in
The valves of the thermal management system 52 and the climate control system 50 may be actuated such that the cabin loop 54 and the battery loop 74 operate as separate thermal circuits. For example, this may occur during preconditioning when only the cabin is being heated.
Because the charging station has limited power output and the heater has limited heating output, the controller may have to prioritize and choose which components to heat, and which components not to heat, based on certain conditions. Referring to
If only cabin heating is currently requested, control passes to operation 308 and the cabin is heated according to the following steps. The vehicle, for example vehicle 212, may enter a cabin only heating mode by actuating the valves 270 and 286 into certain positions. For example, at operation 310 the controller may send a signal to the valves 270, 286 instructing the valves to the position shown in
If at operation 304 it is determined that the cabin is not requesting heat, or that the battery is requesting heat, control passes to operation 320. If at operation 320 only the battery is requesting heat, control passes to operation 322 and the battery is heated. The vehicle, for example vehicle 12, may enter a battery only heating mode by actuating the valves 72, 82, and 86 into certain positions. For example, at operation 324, the controller may send a signal to the valves 70, 82, and 86 instructing the valves to the position shown in
If it is determined that the cabin and the battery are requesting heating, control passes to operation 330. At operation 332 the controller determines if the time from now to the next planned usage is less than a first time threshold (T1). T1 may be a time that is longer than a time required to heat the cabin. For example, T1 may be in a range between 90 and 30 minutes inclusive. If the time to the next planned usage is greater than T1, then control passes to operation 322 and only the battery is preconditioned because preconditioning of the cabin need not occur yet. If at operation 322 the time to the next planned usage is less than T1, then control passes to operation 334. At operation 334 the controller determines if the time from now to the next planned usage is greater than a second time threshold (T2). For example, T2 may be in a range between 2 to 20 minutes inclusive. T2 may represent an optimal time to begin heating the cabin. Both T1 and T2 are calibrated values that may be a function of the ambient air temperature, the magnitude of the wall power, and the size of the heat sink. The controller may include one or more look up tables having a plurality of different T1 and T2 values depending upon those parameters.
If the time to the next usage is not greater than T2, control passes to operation 308 and only the cabin is preconditioned because the time to next planned usage is too soon to have any effect on the battery. If the time the next usage is greater than T2, control passes operation 336. When the time to next planned usage is less than T1 and greater than T2, both the cabin and the battery are a candidate for heating if a sufficient amount of wall power is available. At operation 336 the controller determines if the available wall power (e.g. power supplied by the charging station) is above a power threshold (Pt), which represents a minimal amount of power required to heat both the battery and the cabin. The power threshold may based, at least in part on, temperature of the ambient air. For example, Pt may be 2 kW. If the available wall power is below Pt, then insufficient power is available to heat both the cabin and the battery. Thus, one must be prioritized over the other. In control logic 300, the battery is prioritized over the cabin. As such, if insufficient power is determined at operation 336, control passes to operation 322 and only the battery is heated. But, if sufficient wall power is available, control passes to operation 338 and both the cabin and the battery are preconditioned. At operation 340 the valves are actuated such that both the battery and the cabin are heated. For example, the valves 70, 82, and 86 are actuated such that the battery cooling loop 74 and the cabin cooling loop 54 form a single thermal circuit as is shown in
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and can be desirable for particular applications.