Powertrain control based on auxiliary battery characteristics

Abstract

The present disclosure relates to powertrain control based on auxiliary battery characteristics. A powertrain control system may include an engine and a controller. The controller may be configured to activate an automatic stop-start system of the engine in response to a maximum difference in battery voltage values ​​remaining less than a threshold value during a period in which the number of engine stop-start cycles exceeds a limit.

Description

Technical Field

[0001] The present application generally relates to a vehicle control system configured to disable engine start-stop or smart regenerative charging based on battery characteristics. Background Art

[0002] Many vehicles include an internal combustion engine, a battery (e.g., a 12-volt lead-acid battery), a starter, an alternator, and the vehicle's electrical loads. Typically, the battery is charged by the alternator when the engine is running and discharged when the engine is not running. Recently, smart regenerative charging (SRC) and automatic start-stop (SS) functions have been added to conventional vehicles to improve vehicle fuel economy and reduce emissions. Summary of the Invention

[0003] A powertrain control system may include an engine and a controller configured to activate an automatic stop-start system of the engine in response to a maximum difference in battery voltage values ​​remaining less than a threshold value during a period in which a number of engine stop-start cycles exceeds a limit.

[0004] A method of a vehicle powertrain system executed by a controller includes disabling automatic engine stop-start in response to a battery voltage change exceeding a threshold while a battery current change is below a low current threshold, and enabling the automatic stop-start in response to the voltage change exceeding the threshold while a battery current is above the low current threshold for a number of engine start cycles exceeding a limit.

[0005] A powertrain control system may include an engine and a controller. The controller may be configured to activate an automatic stop-start system of the engine in response to a maximum difference in battery voltage values ​​remaining less than a threshold value during a period in which a number of engine stop-start cycles exceeds a limit, and an average battery voltage within the period being less than an operational threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic diagram of a vehicle with a start-stop control system.

[0007] Figure 2 is a graph of the battery voltage curve and the battery current curve relative to time.

[0008] Figure 3 is a graphic representation of the battery resistance curve versus engine cranking cycles.

[0009] Figure 4 It is a flow chart of the powertrain control system. DETAILED DESCRIPTION

[0010] Embodiments of the present disclosure are described herein. However, it will be understood that the disclosed embodiments are merely examples and that other embodiments may take various alternative forms. The drawings are not necessarily drawn to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art to utilize the present invention in various forms. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any of the figures may be combined with features shown in one or more other figures to produce embodiments that are not explicitly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, various combinations and variations of features consistent with the teachings of the present disclosure may be desired for specific applications or implementations.

[0011] Vehicles typically include lead-acid batteries for powering accessories and a starter motor for the internal combustion engine. As batteries age, the connection between the battery cells and the vehicle's electrical system may become disconnected due to corrosion on the battery posts, battery terminals, or the interface between the posts and terminals. Furthermore, after the engine has been started, the battery posts or terminals may become disconnected due to vehicle vibration. Here, the battery posts are the battery's connection ports, which introduce the current and voltage of the internal battery cells into the vehicle, while the battery terminals are connectors configured to connect to the battery posts to connect the battery cells to the vehicle's electrical system. While the engine is running, disconnection or damage to the battery terminals from the battery posts can cause the engine to stall or increase the stall speed, below which the engine will stall. Typically, when the battery is disconnected after the engine is running, the engine and vehicle can continue to operate while the vehicle's alternator generates more power than required for vehicle operation. Therefore, when the alternator generates less power than required for engine operation, the engine may stall. Furthermore, if the engine is shut down after the battery unit is disconnected from the vehicle electrical system, the vehicle will not be able to restart, thereby stranding the vehicle. This is particularly concerning when the vehicle is operating in Smart Regenerative Charging (SRC) for hybrid vehicles and / or automatic engine stop-start (SS) for hybrid or conventional internal combustion engine-powered vehicles.

[0012] When the vehicle is accelerating, the engine is inefficient. The SRC function takes advantage of this and turns off the AC generator during acceleration to save fuel and reduce emissions. Therefore, during SRC, the entire vehicle load, including the vehicle's ignition switch, is (sometimes) powered solely by the battery. And when there is available energy (for example, when the brake pedal is pressed, the foot is removed from the accelerator pedal, coasting downhill, etc.), the battery is charged via the AC generator. The SS function is a control of the engine, in which the engine is stopped when the vehicle is stopped by the brake pedal to save fuel and reduce emissions. When in SS mode, the ignition switch is turned on and the engine is stopped, and the engine will automatically start when the brake pedal is released and the accelerator pedal is pressed.

[0013] During both SRC and SS operation, the alternator can be shut down to allow the battery to support the vehicle electrical loads. Therefore, it is critical to maintain battery power during SRC and SS operation.

[0014] One possible battery failure mode that results in a disconnection of battery power is a disconnection between the battery electrodes (i.e., battery terminals) and the battery cables connected to the vehicle's electrical loads. Another possibility is corrosion of the connections between the battery electrodes and the battery cables. Additionally, the battery cables may be improperly connected to the battery electrodes. Additionally, the connections between the battery electrodes and the battery cables may be damaged by vehicle vibrations. In any of these or other conditions that result in a faulty, damaged, disconnected, or high-resistance connection, an engine stall may occur, after which the engine may fail to automatically start after an engine stop.

[0015] Disclosed herein is a battery fault detection algorithm for detecting battery electrode connection failure. Due to the electrical connection between the battery electrodes and the battery cable, the battery current will generally change when the battery voltage changes. When the battery electrodes are disconnected from the cable or the connection has high resistance, the battery current will remain at or approximately zero and may not change when the battery voltage changes. Therefore, if the battery current is always substantially zero at different battery voltages, a failure in the battery electrode connection can be detected. When a battery electrode connection failure is detected, the vehicle SRC, automatic start-stop, and other critical vehicle operations can be disabled by the battery management system (BMS) so that the vehicle AC generator is always on. Corresponding DTCs (diagnostic trouble codes) and warnings can be generated.

[0016] As mentioned above, the connection between the battery electrodes and the battery cables may be damaged due to corrosion of the battery electrodes or due to vehicle vibration. These conditions may cause fluctuations in the resistance between the battery electrodes and the battery cables. The battery resistance can be monitored by a battery sensor. For example, the battery sensor may be located in a battery module connected to the battery terminals and is used to measure the battery current, voltage, and temperature, which can then be used to estimate the battery resistance. This resistance may include the internal resistance of the battery and the resistance between the battery electrodes and the battery cable. When the connection is damaged, the monitored battery resistance may fluctuate. The controller may monitor and detect the fluctuation, and when the fluctuation exceeds a threshold, the controller may disable the SRC and SS and generate corresponding DTCs and warnings.

[0017] Most hybrid electric vehicles (HEVs) have an auxiliary battery (e.g., a 12 volt battery) to provide power to vehicle lighting, control modules, climate blowers, electric power steering (EPAS), and other low voltage electrical loads within the vehicle. In HEVs, a DC / DC converter is typically used to charge the 12 volt battery. The battery connection algorithms and systems disclosed in this application may also be applicable to HEVs and other electrified vehicles. For example, when a damaged battery connection is detected in an HEV, the DC / DC converter may be configured so that power may be selectively used for vehicle operation. Critical vehicle operations (e.g., cruise control, EPAS) may be disabled, and corresponding DTCs and warnings may be set. In addition, such algorithms and systems may also be used in autonomous vehicles (AVs). When a disconnected or loose battery electrode connection is detected, critical operations may be disabled during autonomous operation, and a DTC may be set to warn the driver to disable the vehicle's automatic operation.

[0018] In addition to lead-acid batteries, other battery chemistries such as lithium-ion batteries are also used. Using lithium-ion batteries instead of lead-acid batteries reduces weight and improves performance. However, when using lithium-ion batteries, a self-protection relay can be connected between the battery pole and the battery cell. Under extreme conditions (for example, very high or very low voltage, very high or very low temperature), the battery module controller can disconnect the battery cell protection relay, thereby disconnecting the battery pole. Here, the system detects the battery pole disconnection and adjusts the corresponding vehicle warnings and powertrain control. The vehicle can be a traditional internal combustion engine vehicle or a hybrid electric vehicle.

[0019] Here, upon detecting a battery post disconnect, the controller will set a flag (e.g., BattPoleFailureFlag = TRUE) in a module (e.g., a body control module 'BCM' or a powertrain control module 'PCM'). The detection may be based on the value and / or change of the battery current and / or battery voltage. In a conventional vehicle with an internal combustion engine, a battery disconnect may be detected immediately when either battery post (i.e., the negative post or the positive post) is disconnected and the engine is running. However, in an EV / FHEV / PHEV / or autonomous vehicle (e.g., with a 12 volt battery charged via a DC / DC converter), a battery disconnect may be detected immediately after a change in the vehicle electrical load (e.g., turning on / off a light, opening a door, or turning on / off a radio, etc.).

[0020] Similarly, when a battery pole is detected to be disconnected based on the value and / or change of the battery resistance measured by the vehicle battery monitoring system (BMS), a flag (e.g., BattPoleFailureFlag) is set. The BMS may include a module connected to the battery pole that is configured to measure the characteristics of the battery (such as voltage, current, and resistance). As described above, a resistance-based determination may be used to supplement the determination using current and voltage. In this application, the term "battery failure" is used to describe a condition in which a battery connection failure exists.

[0021] Once a disconnect is determined, the powertrain controller can limit functionality, for example, the powertrain controller can disable smart regenerative charging (SRC) and automatic stop-start (SS) operating modes based on a flag (e.g., BattPoleFailureFlag = TRUE). Smart regenerative charging (SRC) is the use of the high voltage of the AC generator to charge the battery when the vehicle is in a low load condition (e.g., vehicle deceleration, vehicle stop). In some cases, the AC generator provides a braking function during vehicle deceleration while generating electricity from the AC generator by converting vehicle deceleration into energy. Conversely, during high vehicle load conditions (e.g., acceleration or engine operation in a low-efficiency mode), the AC generator can be turned off so that no electricity is generated or electricity is reduced to reduce fuel consumption. When the vehicle is traveling at a constant speed, the AC generator can be controlled to charge the battery based on the battery SOC (state of charge).

[0022] A battery warning may then be generated to notify the vehicle's driver. The battery warning may include illuminating a symbol on the vehicle's instrument cluster, or outputting an audible alert via a speaker, a piezoelectric element, or the battery warning may be transmitted via the infotainment system. Subsequently, a diagnostic trouble code (DTC) may be set.

[0023] To disable the battery warning, clear the DTC, and unblock the SRC and SS functions, a flag must first be cleared (BattPoleFailureFlag = FALSE) based on the conditions (e.g., the value and change of voltage, current, or resistance) and the number (e.g., 3, 5, or 10) of successful engine starts (for conventional vehicles with internal combustion engines or hybrid vehicles) or the number (e.g., 3, 5, or 10) of vehicle sleep / wake cycles (for EV / FHEV / PHEV / or autonomous vehicles with auxiliary batteries charged via a DC / DC converter). These steps are also applicable to vehicles with different battery voltages and battery chemistries (e.g., 12 volts, 24 volts, 48 ​​volts, low voltage power grids (LVPNs) with dual batteries, lithium-ion battery systems, lead-acid battery systems, and other high voltage batteries).

[0024] Conventional start-stop systems can be configured to automatically stop the engine when the vehicle is not moving (e.g., 0 mph), force is applied to the brake pedal, and the voltage level of the vehicle battery is above a threshold. The threshold is selected based on the energy required to start the engine via the electric starter. Once the engine is stopped, the controller can automatically start the engine when the gear selector is in Drive and no force is applied to the brake pedal. In other embodiments of start-stop vehicles, the controller can be configured to automatically stop the engine when the vehicle is moving below a low speed threshold (e.g., 2 mph or 4 mph), force is applied to the brake pedal, and the voltage level of the vehicle battery is above a threshold. When the vehicle is moving, the threshold is higher because the vehicle still requires some power to activate the electric power brakes and EPS. In addition to conventional start-stop control systems, vehicles can be configured to start-stop the engine when the vehicle is moving above a lower threshold. This system is also known as a rolling start-stop system (RSS).

[0025] RSS can offer additional benefits, such as improved fuel economy ratings, improved vehicle emissions, and reduced engine noise. These benefits are in addition to improvements to traditional start-stop systems. Once the driver applies the brakes and the vehicle speed is below an upper speed threshold, RSS allows the engine to automatically stop at higher speeds. For example, using RSS can improve fuel economy by approximately 2.4% and reduce carbon emissions by approximately 9 CO2 g / mi. In order for RSS to combine the aforementioned benefits of improved fuel economy and reduced carbon emissions without compromising drivability and the noise associated with it, a reliable and stable power source is required to operate critical and safety components during the engine auto-stop.

[0026] Generating energy through the engine only when needed / required is one of the primary ways to maximize fuel economy while minimizing emissions in vehicles equipped with internal combustion engines. Consequently, SS / RSS systems are being considered for implementation on a range of modern vehicles in all major world markets. An SS / RSS system may include a battery system that may be implemented as a single cell, dual cells, or any number of cells. The operating voltage of the battery system may be approximately equal to the vehicle battery standard (i.e., 12 volts), or the battery system may operate at other voltages (e.g., 24V, 48V, etc.). An SS / RSS system may utilize any combination of the same or different battery or power source technologies, such as lead-acid, enhanced flooded battery (EFB), absorbent glass mat (AGM), lithium-ion, or any other battery technology.

[0027] Reference Figure 1 The micro-hybrid vehicle 100 (also known as a start-stop vehicle) includes an engine 102 and a transmission 104. The crankshaft of the engine 102 is drivably connected to a transmission input shaft 106 to transmit power from the engine to the transmission. The transmission 104 includes an output shaft 108, which is drivably connected to a differential 110. The differential 110 selectively provides power to drive wheels 114A and 114B via one or more axles (such as half shafts 112A and 112B). In some embodiments, the differential 110 is disposed within the transmission housing. The vehicle 100 also includes an engine starter motor 116, which is configured to rotate the crankshaft to turn over the engine 102 in response to an engine start signal from a controller 120. The engine starter motor 116 can be an enhanced starter motor specifically designed for the increased duty cycle associated with micro-hybrid vehicles. Starter 116 is powered by battery 118, which may be a 12-volt battery, a 24-volt battery, a 48-volt battery, or other low-voltage or high-voltage battery. A low-voltage battery is a battery with a DC voltage less than 100 volts, and a high-voltage battery is a battery with a DC voltage equal to or greater than 100 volts. In some embodiments, the engine may include multiple starter motors. A first starter motor may engage the ring gear of the flywheel to start the engine. A second starter motor may be connected to the crankshaft pulley via a belt, chain, or other means known in the art.

[0028] An accelerator pedal 122 provides operator input to control the speed of the vehicle 100 . The pedal 122 may include a pedal position sensor for providing a pedal position signal to the controller 120 , which provides a control signal to the engine 102 .

[0029] Brake pedal 124 provides operator input to control the vehicle's brakes. Brake controller 126 receives operator input via brake pedal 124 and controls a friction braking system including wheel brakes 130A and 130B, which is operable to apply braking force to vehicle wheels (such as vehicle wheel 114A and vehicle wheel 114B). Pedal 124 may include a pedal position sensor for providing a pedal position signal to controller 120. The vehicle may include an electric parking brake in communication with controller 120. Controller 120 is configured to automatically engage the electric parking brake when required.

[0030] The controller 120 can be a plurality of controllers communicating via a serial bus (e.g., a controller area network (CAN), FlexRay, Ethernet, etc.) or via a dedicated electrical conduit. A controller typically includes any number of microprocessors, microcontrollers, ASICs, ICs, volatile memory (e.g., RAM, DRAM, SRAM, etc.) and non-volatile memory (e.g., FLASH, ROM, EPROM, EEPROM, MRAM, etc.) and software code to cooperate with each other to perform a series of operations. The controller may also include predetermined data or "lookup tables" based on calculations and test data and stored in memory. The controller may communicate with other vehicle systems and controllers using a common bus protocol (e.g., CAN, LIN, Ethernet, etc.) through one or more wired or wireless vehicle connections. References to "controller" as used herein refer to one or more controllers.

[0031] As described above, embodiments of the present disclosure include a control system for controlling a start-stop system for an engine in a vehicle (such as engine 102 and vehicle 100). Such a control system may be implemented by one or more controllers (such as controller 120). One goal of a vehicle start-stop system is to automatically stop the engine under certain conditions and automatically restart the engine when the conditions change. This provides greater fuel economy and emissions reductions.

[0032] In some start-stop systems, the engine can be automatically stopped (auto-stop) when a set of conditions are all met. For example, if the shift lever is in Drive, the brake pedal is pressed, the accelerator pedal is released, and the vehicle speed is zero, the engine 102 can be automatically stopped. Another condition that can be included in this set of conditions is that no vehicle subsystems (e.g., air conditioning or power steering) require the engine to be running. In start-stop systems that require all conditions to be met before the engine automatically stops, the start-stop system will not only prohibit the engine from automatically stopping if any of the conditions in the set are not met, but once the engine has been automatically stopped, the engine can automatically restart if any of the conditions change.

[0033] Continuing with the above example, one common condition that causes the engine to stop is when the vehicle's speed is zero. Typically, the engine will not stop while the vehicle is in motion. In some systems, the vehicle's speed may be greater than zero, but less than a lower speed threshold (such as 3 kph or 5 kph). Here, the rolling start-stop system allows the engine 102 to automatically stop when the vehicle's speed is within a speed range. The speed range includes an upper threshold speed and a lower threshold speed. The lower threshold speed may be a speed at which the vehicle can be stopped using the emergency brake (such as 0 mph, 2 mph, or 5 mph). At the lower threshold speed, the voltage level threshold of the starter battery 118 is selected to provide the amount of charge required to operate the vehicle's electrical components, which are powered by the battery 118. The upper threshold speed may be a speed associated with the voltage of the starter battery 118, which indicates the state of charge required to operate the vehicle's electrical components (including electric power steering (EPS), electric power brakes, electronic stability control (ESC), and other vehicle dynamic systems) while the vehicle is in motion. In addition to the vehicle control systems there are also vehicle comfort systems (such as seat heaters, air conditioning systems, and window defrosters) which can use considerable power and may need to be accounted for in the battery voltage calculation.

[0034] Another vehicle characteristic to consider when calculating the engine shutoff point is the capacity and pressure of the vacuum reservoir used to provide brake boost vacuum assistance. The upper threshold speed can be selected from a speed range, such as 15 mph to 60 mph. A vehicle's ability to steer and stop depends on many vehicle conditions, including speed, weight, bank angle, braking conditions, road conditions, and tire conditions. As these conditions change, the vehicle's ability to steer and stop also changes. For example, a vehicle traveling downhill is more difficult to stop than one traveling uphill. Therefore, controller 120 can be configured to set a fixed lower threshold based on lower speeds to protect against a range of conditions that may affect vehicle stopping. Alternatively, controller 120 can be configured to set a fixed upper threshold based on higher speeds to protect against a range of conditions that may affect vehicle stopping. Alternatively, controller 120 can be configured to dynamically change the lower and upper thresholds based on the vehicle's condition at a given point in time.

[0035] The controller 120 may also be configured to dynamically change the lower and upper thresholds based on the vehicle's conditions at a future point in time. For example, the navigation system 132 may be connected to the controller 120 so that it can provide a route to the controller. The route may include changes in elevation along the route, and the upper and lower speed thresholds may be adjusted based on changes in potential braking along the route. The route may also include changes in posted speeds, which indicate locations where the brakes can be applied to slow down or the accelerator pedal can be used to speed up. The route may include locations of potential stops (such as static locations and dynamic locations). Static locations of potential stops include traffic lights, stop signs, roundabouts, or yield signs. Dynamic locations of potential stops along the route include locations associated with traffic jams, weather conditions, road construction, or accidents. The route displayed by the navigation system 132 may be generated based on map data preloaded into the system 132's memory, or the system 132 may receive data transmitted from a remote server. The data may be transmitted wirelessly using cellular, Wi-Fi, or other standard technologies. Based on the route, changes in altitude, and potential stops along the route, the controller 120 can adjust the voltage level of the starter battery 118 to maintain the state of charge of the starter battery 118, thereby conserving power for electrical accessories powered by the battery 118, including electric power steering (EPS), electric power brakes, electronic stability control (ESC), and other vehicle dynamic systems.

[0036] There are situations where restarting may not be desirable, such as when the operator intends to put the vehicle in Park and shut off the engine, or when the operator intends to put the vehicle in Neutral and remain stopped. Therefore, in at least some embodiments of the present disclosure, controller 120 is configured to account for these varying needs. For example, when engine 102 has been automatically stopped while the vehicle is in Drive and the shift lever of transmission 104 is shifted out of Drive, controller 120 may be configured to automatically restart engine 102 under at least one condition and prohibit automatically restarting engine 102 under at least one other condition.

[0037] This can be done by means of a flow chart or similar diagram (e.g. Figure 4 400 in FIG. 4 to represent the control logic or functions executed by the controller 120. Figure 4Representative control strategies and / or logic that can be implemented using one or more processing strategies (such as polling, event-driven, interrupt-driven, multi-tasking, multi-threading, etc.) are provided. Thus, the various steps or functions shown may be performed in the sequence shown, in parallel, or omitted in some cases. Although not always explicitly shown, one of ordinary skill in the art will recognize that one or more of the steps or functions shown may be repeated, depending on the specific processing strategy used. Similarly, the processing order is not required to achieve the features and advantages described herein, but is provided for ease of illustration and description. The control logic may be primarily implemented in software executed by a microprocessor-controlled vehicle, engine, and / or powertrain controller (such as controller 120). Of course, depending on the specific application, the control logic may be implemented in software, hardware, or a combination of software and hardware in one or more controllers. When implemented in software, the control logic may be provided in one or more computer-readable storage devices or media storing data representing code or instructions executed by a computer to control the vehicle or its subsystems. Computer-readable storage devices or media may include one or more of a number of known physical devices that utilize electrical, magnetic, and / or optical storage to retain executable instructions and associated calibration information, operating variables, and the like.

[0038] Figure 2 FIG2 is a graph 200 of battery current 202 and battery voltage 204 relative to time 206. A battery current curve 208 and a battery voltage curve 210 are shown relative to time 206. During an operating window starting at time 110 seconds until time 212, at which the battery post is disconnected from the battery terminal connector, the battery current curve 208 fluctuates around 65 amperes. At disconnection time 212, the battery current drops to approximately 0 amperes. Furthermore, during an operating window starting at time 110 seconds until time 212, at which the battery post is disconnected from the battery terminal connector, the battery voltage curve 210 fluctuates between approximately 13.88 volts and 13.94 volts. Prior to disconnection time 212, a normal operating voltage fluctuation 214 is approximately 0.06 volts. At the disconnect time 212 , the battery voltage increases to a peak value 218 and then stabilizes in a fault range fluctuating between 13.94 volts and 14.06 volts, so after the disconnect time 212 , the disconnect voltage fluctuation 216 is approximately 0.12 volts, which is approximately twice the magnitude of the normal operating fluctuation 214 .

[0039] Battery disconnect time 212 includes the time when the resistance of the battery changes due to loose or disconnected electrodes. When the engine is running and the battery is connected or disconnected via a resistive path, the engine can still operate based on the output of the vehicle's alternator. Typically, when the vehicle is idling, the revolutions per minute fluctuate around a typical idle speed. However, some of the low speeds during these fluctuations may fall below the alternator threshold speed required for engine power operation, causing the engine to stall. The system can increase the average idle speed when a battery disconnection or an increase in battery resistance is detected to reduce the risk of stalling by preventing the alternator speed from dropping below the battery disconnect speed threshold or by prohibiting engine shutdown in a stop-start (SS) vehicle to maintain power flow from the alternator.

[0040] Many vehicles have a battery management system (BMS) that is configured to measure battery current and voltage. The battery current and voltage are typically measured by a BMS module or a battery sensor connected to the negative battery post or connector. The voltage and current signals from the BMS can then be used by other vehicle modules, such as the body control module (BCM) and the powertrain control module (PCM). Both battery current and voltage measurements are still taken when the battery post is disconnected or loose. When the battery post is disconnected, the measured current is zero, and the measured voltage is the voltage across the positive and negative battery terminals or connectors.

[0041] One example is a vehicle (such as a hybrid vehicle or a conventional vehicle) in which smart regenerative charging (SRC) or stop-start (SS) mode is enabled. When SRC is enabled and during specific vehicle operating events, the controller may adjust (e.g., reduce) the target alternator voltage to improve vehicle fuel economy. Specific vehicle operating events may include a vehicle acceleration request exceeding a threshold or a vehicle deceleration request falling below a threshold (e.g., the driver rapidly changes the force applied to the accelerator pedal). Specific vehicle operating events may also include vehicle operations such as a vehicle stop and thereby the engine dropping to a low idle, or during a transmission shift, during which the engine RPM is reduced due to the engagement of the clutch, causing the wheel speed and the selected transmission gear ratio to thereby reduce the engine speed associated with the wheels and the transmission. When the target alternator voltage is set to a low voltage set point, the alternator may be disabled. In addition, if the vehicle initiates an automatic stop when a battery connection problem has occurred, the vehicle may subsequently be unable to automatically start the engine.

[0042] Another example is a vehicle (such as a hybrid or conventional vehicle) in which Smart Regenerative Charging (SRC) or Stop-Start (SS) modes are disabled. In this example, the battery acts as a capacitor in addition to being a power source in the charging system. Therefore, the vehicle voltage is the output of the alternator, and the battery acts as a large capacitor to filter and stabilize the vehicle voltage. When the battery is disconnected, the vehicle voltage may experience large oscillations due to the alternator voltage regulation characteristics and the dynamic characteristics of the vehicle's electrical loads. These large oscillations can cause the voltage to drop below a low-voltage threshold, after which an engine stall may occur.

[0043] Another example is a vehicle (such as a hybrid or conventional vehicle) with a self-protecting battery module. For example, a 12-volt lithium-ion battery module may include a self-protection relay. When the battery voltage rises above an upper threshold or falls below a lower threshold, or when the battery temperature rises above a corresponding upper temperature threshold or falls below a corresponding lower temperature threshold, the relay is automatically disconnected by a controller, and the battery terminal is disconnected from the battery cells within the battery.

[0044] Figure 3 FIG300 is a graph of battery resistance 302 relative to engine start cycles 304. A battery resistance curve 306 is based on measurements of voltage and current during operation, including engine start cycles. Here, a first battery resistance 308 associated with a first engine start cycle is based on battery current and battery voltage. A second battery resistance 310 associated with a second engine start cycle is based on battery current and battery voltage. A third battery resistance 312 associated with a third engine start cycle is based on battery current and battery voltage. Battery resistance points (308, 310, 312) can be plotted and connected to form battery resistance curve 306. Based on the values ​​of battery resistance curve 306, a controller can output a warning to a vehicle operator when resistance exceeds a first threshold, and can also change a powertrain operating mode when battery resistance curve 306 exceeds a second threshold, wherein the second threshold is greater than the first threshold. Often, battery posts and corresponding battery terminal connectors become loose for a period of time before disconnection. Therefore, detecting loose battery posts is important for ensuring vehicle operation. Typically, the BMS module measures battery resistance during each start and during operation. Battery resistance is the sum of the battery's internal resistance and the battery post resistance, which is the resistance between the battery post and the battery terminal connector. When the battery post is properly connected to the battery terminal connector, the battery post resistance is generally close to zero. For example, under similar battery operating conditions (e.g., similar battery SOC and temperature) and when the battery post is properly connected to the battery terminal connector, the value of Ri is stable for different engine starts and varies by less than 5%. However, when the battery electrode is loose, Ri varies significantly. Figure 3 Depicted is the change in Ri measured by the BMS module when a battery electrode becomes loose in a test vehicle.

[0045] Here, faults can be detected and cleared based on the value and change in value of the battery resistance. For example, if the change in the battery resistance value is greater than a threshold (e.g., a change greater than 20%, or a change in resistance exceeding 2 mOhm) over three consecutive engine start cycles, a battery fault can be determined and vehicle operation can be adjusted accordingly. Vehicle operation can include SRC, SS, or idle speed. Furthermore, the fault can be cleared when the change in resistance measured over three consecutive engine start cycles is less than 5% or 0.5 mOhm.

[0046] Figure 4 4 is a flow chart diagram 400 of a powertrain control system. The flow chart diagram 400 depicts an algorithm that can be used to operate a vehicle with an auxiliary battery. When the battery post is disconnected while the engine is running (or the DC / DC converter is operating), vehicle operation can be supported by the vehicle's AC generator or DC / DC converter while the battery current is approximately zero. When the battery post is disconnected, (1) the battery current measured by the battery current sensor is less than the maximum tolerance of the battery current sensor, (2) the change in battery current between different sampling times is approximately zero, and (3) the absolute value of the change in battery voltage between different sampling times is greater than a voltage change threshold. Note that in a physical sense, the battery current does not change when the change in battery voltage is greater than the voltage change threshold (e.g., a calibrable value such as 0.1 volt).

[0047] Both vehicle and experimental data show that even when the battery is fully charged or the battery temperature is very low, the battery current changes when the voltage change is greater than a voltage change threshold. For example, the controller can detect this condition based on a detectable current change less than a threshold corresponding to a voltage change (e.g., less than 0.01 amps with a corresponding voltage change of 0.1 V or less). In practice, a current change of approximately 0.0625 mA has been observed to correspond to a voltage change of 0.1 V.

[0048] When the vehicle is first powered on and the battery is operating normally (based on factors including battery voltage, fluctuations in battery voltage, battery current, and battery resistance), in operation 402, the controller enables SRC and / or SS (if equipped), clears diagnostic trouble codes (DTCs) associated with battery faults, and sends a signal to turn off warning indications (e.g., audible indications or visual indications (such as instrument cluster warning lights)). The controller will then proceed to operation 404. In operation 404, the controller receives (or, in some embodiments, measures) battery characteristics, including battery current, battery voltage, and battery resistance. These data or battery characteristics may indicate both battery characteristics at a point in time and battery characteristics over a period of time. The controller will then proceed to operation 406.

[0049] At operation 406, the controller will evaluate the data to determine if the battery is in a fault condition. The controller will then proceed to operation 408. A fault condition may be determined based on changes in battery characteristics and battery condition.

[0050] For example, a fault condition may be based on an average voltage level when the vehicle is operating in a particular mode (e.g., engine running, shifter in park, limited electrical loads enabled). Figure 2 As shown, when the battery is connected, the battery voltage (no fault) is limited to 13.92V and then increases to a limited battery voltage (fault) of 14.08V, which is an increase of 0.10V from the connected (no fault) voltage. In another example, the fault condition can be based on the maximum change in voltage level over a period of time. Figure 2 As shown, the change in battery voltage (no fault) is 0.06V, which then increases to a change in battery voltage (fault) of 0.12V, which is twice the voltage change of the connected (no fault) voltage. Another example is where the fault condition is based on the level of current associated with the battery. Figure 2 As shown, the battery current measured while the vehicle was running (no fault) was shown to be approximately 65 amps, then decreased to approximately 0 amps after the battery post was disconnected (fault). Based on the occurrence of one of these fault conditions, the controller will branch to operation 408.

[0051] At operation 408, the controller will branch based on the type of vehicle. The type of vehicle can distinguish electrified vehicles, such as vehicles that can be propelled by electrical energy (e.g., in this illustrative example, classified as electric vehicles (EVs), full hybrid electric vehicles (FHEVs), plug-in hybrid electric vehicles (PHEVs), or autonomous vehicles). Generally, an electric vehicle (EV) is a vehicle that can move the vehicle from a complete stop to a minimum speed (e.g., 25 mph) within a predetermined distance when engaged in gear. Typically, EVs are broken down into more specific categories, for example, a battery electric vehicle (BEV) uses only power from the battery, so the vehicle stops when the battery is depleted. An extended-range electric vehicle (EREV) is an electric vehicle that can continue to travel via an auxiliary internal combustion engine (ICE) after the battery is depleted. A fuel cell electric vehicle (FCEV), also known as a hydrogen vehicle, uses a fuel cell to generate electricity and propulsion. A hybrid electric vehicle (HEV) includes an ICE that receives occasional acceleration assistance from a traction battery. A plug-in hybrid electric vehicle (PHEV) is an HEV that has the ability to plug in to recharge the traction battery using power from the grid. However, mild hybrid electric vehicles (LHEVs) that use minimal power and include systems such as a "start-stop system" or "electric assist system" to reduce gas consumption (e.g., stopping the ICE primarily at idle or when the vehicle is stopped at a stop light or in very slow traffic) may be classified as traditional ICE vehicles. LHEVs generally do not have enough power to move the vehicle in gear at minimum speed, but can still assist the ICE at higher speeds and higher power demands. Additionally, autonomous vehicles may be classified separately because they are typically equipped with an automatic stop-start (SS) system. Here, if the vehicle is an EV, FHEV, PHEV, or autonomous vehicle, the controller will branch to operation 410, and if the vehicle is not an EV, FHEV, PHEV, or autonomous vehicle, the controller will branch to operation 412.

[0052] In operation 410, the controller will branch based on changes in the vehicle's electrical load and the battery being in a battery failure condition. In an EV, FHEV, PHEV, or autonomous vehicle, an auxiliary low-voltage or 12-volt battery can be charged via a DC / DC converter connected to the high-voltage system (including the high-voltage battery or traction battery). In this configuration, disconnection of the auxiliary battery can be detected after a change in the vehicle's electrical load (e.g., turning on / off a light, opening a door or hatch, turning on / off the radio or infotainment system). If the vehicle's electrical load has changed, the controller will branch to operation 414. If the vehicle's electrical load has not changed, the controller will branch to operation 418.

[0053] At operation 412, the controller branches based on whether the engine is running and the battery is in a battery failure condition. In vehicles with a combustion engine that charges the auxiliary battery via an alternator, disconnection of the auxiliary battery can be detected while the engine is running. If the engine is running, the controller branches to operation 414. If the engine is not running, the controller branches to operation 420.

[0054] In operation 414, the controller will set a flag indicating a battery fault as determined in operation 406 and defined by operation 410 or 412. Once the flag is set, the controller will proceed to operation 416, where the controller will disable the SRC and / or SS (if equipped), set a diagnostic trouble code (DTC) associated with the battery fault, and send a signal to turn on a warning indicator (e.g., an audible indicator or a visual indicator such as an instrument cluster warning light). The controller will then proceed back to operation 404.

[0055] Furthermore, if the vehicle electrical load has not changed or the battery is not in a fault condition, the controller will branch to operation 418. At operation 418, if the number of consecutive sleep / wake cycles exceeds the threshold, the controller will branch to operation 402. Furthermore, if the number of consecutive sleep / wake cycles does not exceed the threshold, the controller will branch to operation 404. This threshold and step allows the system to verify that the connection has been restored and is not an intermittent disconnection. If the disconnection is intermittent, the controller will not branch to 402, thereby maintaining the battery fault operating state with increased idle speed and disabled SS and SRC to reduce any risk of the vehicle being stranded.

[0056] Furthermore, if the engine is not running or the battery is not in a fault condition, the controller will branch to operation 420. At operation 420, if the number of consecutive successful engine start cycles exceeds a threshold, the controller will branch to operation 402. Furthermore, if the number of consecutive successful engine start cycles does not exceed the threshold, the controller will branch to operation 404. This threshold and step allows the system to verify that the connection has been restored and is not an intermittent disconnection. If the disconnection is intermittent, the controller will not branch to 402, thereby maintaining the battery fault operating state with increased idle speed and disabled SS and SRC to reduce any risk of the vehicle being stranded.

[0057] The control logic or functions executed by the controller may be represented by flowcharts or similar diagrams in one or more of the accompanying figures. These figures provide representative control strategies and / or logic that can be implemented using one or more processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). Thus, the various steps or functions shown may be performed in the sequence shown, in parallel, or omitted in some cases. Although not always explicitly shown, one of ordinary skill in the art will recognize that one or more of the steps or functions shown may be repeated, depending on the specific processing strategy used. Similarly, the processing order is not required to achieve the features and advantages described herein, but is provided for ease of illustration and description. The control logic may be primarily implemented in software executed by a microprocessor-based vehicle, engine, and / or powertrain controller (such as controller 120). Of course, depending on the specific application, the control logic may be implemented in software, hardware, or a combination of software and hardware in one or more controllers. When the control logic is implemented in software, it may be provided in one or more computer-readable storage devices or media that store data representing code or instructions executed by a computer to control the vehicle or its subsystems. Computer-readable storage devices or media may include one or more of a number of known physical devices that utilize electrical, magnetic, and / or optical storage to retain executable instructions and associated calibration information, operating variables, and the like.

[0058] The processes, methods or algorithms disclosed herein may be transmitted to or implemented by a processing device, a controller or a computer, which may include any existing programmable electronic control unit or a dedicated electronic control unit. Similarly, the processes, methods or algorithms may be stored in a variety of forms as data and instructions that can be executed by a controller or computer, including but not limited to information being permanently stored on a non-writable storage medium (such as a read-only memory (ROM) device) and information being variably stored on a writable storage medium (such as a floppy disk, a magnetic tape, a compact disc (CD), a random access memory (RAM) device, and other magnetic and optical media). The processes, methods or algorithms may also be implemented as software executable objects. Alternatively, the processes, methods or algorithms may be implemented in whole or in part using suitable hardware components (such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a state machine, a controller or other hardware components or devices) or a combination of hardware components, software components and firmware components.

[0059] Although exemplary embodiments have been described above, these embodiments are not intended to describe all possible forms encompassed by the claims. The terms used in the specification are descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of the present disclosure. As previously mentioned, the features of the various embodiments may be combined to form further embodiments of the present invention that may not be explicitly described or illustrated. Although various embodiments may have been described as providing advantages or being superior to other embodiments or prior art implementations in terms of one or more desired characteristics, it will be appreciated by those skilled in the art that one or more features or characteristics may be compromised to achieve desired overall system properties, which depend on the specific application and implementation. These properties may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, and the like. Therefore, embodiments described as being less desirable than other embodiments or prior art implementations in terms of one or more characteristics are not outside the scope of the present disclosure and may be expected to be used in specific applications.

Claims

1. A powertrain control system, comprising: engine; as well as a controller configured to: activate an automatic stop-start system of the engine in response to a battery voltage variation exceeding a threshold while a battery current is above a predetermined current threshold for a number of engine start cycles exceeding a limit; Wherein, the battery supplies power to the starter of the engine.

2. The powertrain control system according to claim 1, wherein: The controller is further configured to disable an automatic stop-start system of an engine in response to the battery voltage changing by more than the threshold while the battery current changing by less than the predetermined current threshold.

3. The powertrain control system according to claim 1 or 2, wherein: The controller is further configured to disable an automatic stop-start system of an engine in response to the battery voltage varying by more than the threshold while the battery current is less than the predetermined current threshold.

4. A method for controlling a vehicle powertrain system, comprising: Do the following via the controller: disabling automatic stop-start of the engine in response to a voltage change of the battery exceeding a threshold while a current change of the battery is below a predetermined current threshold; and activating the automatic stop-start in response to the voltage change exceeding the threshold while the battery current is above the predetermined current threshold for a number of engine start cycles exceeding a limit, Wherein, the battery supplies power to the starter of the engine.

5. The method according to claim 4, further comprising: In response to the voltage change exceeding the threshold while the battery current is below the predetermined current threshold, the automatic stop-start is disabled.

6. A vehicle comprising: engine; as well as a controller configured to: activate an automatic stop-start system of the engine in response to a battery voltage variation exceeding a threshold while a battery current is above a predetermined current threshold for a number of engine start cycles exceeding a limit; Wherein, the battery supplies power to the starter of the engine.

7. The vehicle according to claim 6, wherein: The controller is further configured to disable an automatic stop-start system of an engine in response to the battery voltage changing by more than the threshold while the battery current changing by less than the predetermined current threshold.

8. The vehicle according to claim 6 or 7, wherein: The controller is further configured to disable an automatic stop-start system of an engine in response to the battery voltage varying by more than the threshold while the battery current is less than the predetermined current threshold.

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