Predictive fuel cell restart during low speed operation

A fuel cell electric vehicle is powered by a fuel cell that converts hydrogen gas into electricity to power the vehicle's electric motor. The fuel cell drivetrain includes the fuel cell, traction battery, vehicle controller, and other components. The vehicle controller, also known as an electronic control unit, manages and controls various functions of the vehicle, such as the fuel cell system, engine, and traction battery. It makes decisions based on data from sensors and inputs and optimizes fuel efficiency.

TECHNICAL FIELD

This disclosure relates to vehicle power systems and the control thereof.

BACKGROUND

A proton exchange membrane fuel cell may be used to power a vehicle. The reaction in such a fuel cell involves hydrogen molecules splitting into hydrogen ions and electrons at the anode and causing the electrons to pass through an external load circuit to the cathode side, where protons re-combine with oxygen and electrons to form water and release heat.

SUMMARY

One embodiment is a vehicle. The vehicle is composed of a traction battery, an electric machine, a fuel cell system, and a controller. The controller is programmed to operate the fuel cell system in a specific manner while the vehicle is in a queue of vehicles at a traffic stop. Specifically, while the vehicle is not first in the queue, the fuel cell system operates in such a way that current generated by the fuel cell system does not flow to a traction battery or an electric machine. However, if the data is indicative of the vehicle being first in the queue and stopped, the controller operates the fuel cell system such that the current flows to the traction battery or electric machine.

In addition, the controller may be programmed to selectively operate the traction battery, such that current from the traction battery flows to the electric machine while the vehicle is in the queue, but not first in the queue. The traffic stop may be a traffic light, stop sign, weigh station, or intersection.

The controller is also programmed to maintain the fuel cell system off while the vehicle is in the queue, but not first in the queue. However, if the data is indicative of the vehicle being first in the queue and stopped, the controller can activate and operate the fuel cell system such that the current does not flow to the traction battery or electric machine. Furthermore, the controller can activate and operate the fuel cell system such that the current does not flow to the traction battery or electric machine, provided the fuel cell system is off and the data is indicative of the vehicle being first in the queue and stopped and a traffic light is about to turn green. The data used by the controller can originate from a remote source, such as vehicle sensor data. The present application also relates to a method and a system for implementing the aforementioned features in a vehicle.

A method for operation of a fuel cell system in a vehicle based on certain conditions is presented. When the fuel cell system is turned on and the vehicle is in a queue of vehicles at a traffic stop, but not first in the queue, the system operates in a way that current generated by the fuel cell system does not flow to a traction battery or an electric machine of the vehicle. However, when the data indicates that the vehicle is first in the queue and stopped, the system operates in a way that the current flows to the traction battery or the electric machine.

In addition, the method may involve operating the fuel cell system such that the current from the traction battery selectively flows to the electric machine while the vehicle is in the queue, but not first in the queue. If the fuel cell system is off, the method involves maintaining it off while the data indicates that the vehicle is in the queue, but not first in the queue. If the fuel cell system is off and the data indicates that the vehicle is first in the queue and stopped, and a traffic light is about to turn green, the method involves activating and operating the fuel cell system in a way that the current does not flow to the traction battery or the electric machine.

In one example aspect, a system of a vehicle comprises a controller that is programmed to operate a fuel cell system of the vehicle. If the fuel cell system is turned on and the vehicle is in a predefined traffic condition, the controller ensures that the current generated by the fuel cell system does not flow to a traction battery or an electric machine of the vehicle. When the data indicates an anticipated transition out of the predefined traffic condition, the controller operates the fuel cell system such that the current flows to the traction battery or electric machine. In addition, the controller is further programmed to operate the traction battery such that current from the traction battery selectively flows to the electric machine while the data is indicative of the vehicle being in the predefined traffic condition. The predefined traffic condition can be a traffic light, stop sign, weigh station, or intersection. Moreover, the data that triggers the controller's actions can originate from a source that is remote from the vehicle.

DETAILED DESCRIPTION

Various features illustrated and described with reference to any one of the figures may 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.

The transportation industry is rapidly evolving. An innovation is the fuel cell electric vehicle (FCEV), which is an alternative to traditional gasoline-powered cars. FCEV's are powered by a fuel cell that converts hydrogen gas into electricity to power the electric motor. Power cycling may cause mechanical and chemical degradation of the fuel cell components due to repeated heating and cooling cycles. The internal components of the fuel cell can become chemically and mechanically stressed during the power cycles, which can affect performance over time. Power cycling can also cause the fuel cell to heat if it does not have enough time to cool down between cycles. In certain driving scenarios such as heavy traffic, stop and go traffic, and a line of vehicles in a queue, there are stop and go conditions. During stop and go conditions, the fuel cell of an FCEV may need to be power cycled every time the vehicle needs to move a short distance.

The fuel cell drivetrain can be made up of various components, including the fuel cell, traction battery, vehicle controller, and others. The vehicle controller plays a role in managing various functions of the vehicle, such as the fuel cell system, engine, and traction battery. It makes decisions based on data from sensors and inputs, and optimizes fuel efficiency, allowing for a vehicle mode of operation where the fuel cell produces enough energy to power the vehicle and recharge the traction battery, resulting in a net-energy balance of zero. Here, strategies for conserving hydrogen fuel while maintaining the lifecycle of the FCEV's fuel cell drivetrain are contemplated.

Referring toFIG.1, a vehicle10includes a fuel cell stack12, which is part of the fuel cell system, a traction battery16, an electric machine18, wheels20, one or more controllers22, and may include one or more sensors24. The fuel cell stack12operates by consuming hydrogen and oxygen, and producing electricity in the process. This electricity may be stored in the traction battery16for later use by the electric machine18, which is arranged to transform electrical energy to mechanical energy to propel the wheels20. The various components shown and suggested are in communication with and/or under the control of the one or more controllers22, which can implement the algorithms contemplated herein.

When power from the fuel cell system14of the vehicle10is not required, the system14can choose to shut the fuel cell stack12down or it can command the fuel cell stack12into a net zero power mode for a short duration (the system can operate in this mode for extended periods). In net zero mode, the fuel cell stack12may be configured to produce significantly less power than in a full run mode. In full run mode, the fuel cell stack12is producing enough energy to power the vehicle's electric motor18, as well as its auxiliary systems, while at the same time the energy generated by the fuel cell stack12is being used to recharge the vehicle's traction battery16.

Net zero mode is a state of operation for the fuel cell stack12where the overall energy consumption and production of the fuel cell system14are balanced. The advantage of operating in net zero mode is that it conserves hydrogen fuel, as the fuel cell stack12is not consuming more hydrogen than is being produced, and it also extends the life of the fuel cell system by reducing the amount of stress on the components. In addition, net zero mode helps to minimize the amount of greenhouse gas emissions produced by the vehicle10, as the fuel cell stack12is operating in its most efficient state. This mode of operation is typically used in fuel cell electric vehicles10during periods of low power demand, such as traffic scenarios. These traffic scenarios can be predefined traffic conditions such as during stop-and-go traffic or when the vehicle10is idling. When the power demand of the vehicle10increases, such as when the driver speeds up, the fuel cell system14will automatically switch to a different mode of operation to provide the necessary power.

In net zero mode, the fuel cell stack12may not produce enough power for it to flow to the traction battery16or the electric machine18. However, net zero mode may be high enough to keep the fuel cell stack12ready to produce full power, while not using substantial amounts of fuel. Net zero mode may be achieved by reducing the amount of fuel within the fuel cell stack12. While the vehicle is in net zero mode, the traction battery16may provide power to the electric machine18.

The vehicle controller22, also known as an electronic control unit (ECU), is a component in a fuel cell electric vehicle10that manages and controls various functions of the vehicle10. A typical vehicle controller22consists of a processor, memory, and various input and output interfaces. The processor, typically an embedded microcontroller, is responsible for executing the control algorithms and making decisions based on the data received from the vehicle's sensors24and other inputs. The memory, usually in the form of flash memory or RAM, is used to store the control software and any data that the controller22needs to access.

The vehicle controller22is capable of running sophisticated software programs that control a wide range of vehicle functions, such as the fuel cell system14, the traction battery16, electric machine18, and receiving inputs from the sensors24. The software allows the controller22to monitor various sensors24and inputs, such as the fuel cell stack's temperature, the battery's voltage, and the vehicle's speed, and make decisions based on the data. For example, the controller22can adjust the power output of the fuel cell stack12to optimize fuel efficiency.

The vehicle controller22also receives various inputs from sensors24and other devices throughout the vehicle10, such as the speed of the vehicle10, fuel cell stack12pressure, temperature of the traction battery16, and others. The controller22uses this information to determine the best way to operate the vehicle10and to make decisions about how to control the various systems. For example, the controller22can use data from the vehicle's speed sensor to determine the best time to switch between different modes of operation, such as net zero mode or normal operating mode.

The controller22plays a role in the fuel cell electric vehicle10, serving as the brain of the vehicle's various systems. Its ability to control various functions, receive inputs from sensors, and execute sophisticated software algorithms make it a component for ensuring the vehicle10operates smoothly and efficiently.

The controller22may be configured to detect stop-and-go traffic. There could be certain scenarios during driving where there is stop and go traffic, which may be caused by a stack up of vehicles at a traffic signal, a drive thru, or in heavy traffic. During these stop-and-go conditions, turning the fuel cell stack12ON and OFF every time the vehicle10needs to move a short distance before coming to a stop may not be ideal and can affect fuel cell stack durability. Because the time it takes to restart the fuel cell stack12is much longer than restarting an engine, the fuel cell stack12might not be capable of supplementing traction battery power at the point the driver applies the pedal even if the fuel stack12restart is triggered on brake release. The response can thus also be sluggish because the fuel stack12is not immediately ready to produce power.

When in a queue of vehicles at a stop sign, the fuel cell stack12can be kept shut down until the vehicle10reaches the front of the queue. The fuel cell stack12can then be restarted and enter net zero power mode. At traffic lights, the time to traffic light change information can be received, for example, using vehicle to infrastructure features or detected using a sensor24. The fuel cell stack12can be kept off until just before the traffic light is about to turn green. The fuel cell stack12can then be restarted and enter net zero power mode. For a drive thru or weight station situation, the fuel cell stack12can be kept shut down until the vehicle10reaches the front of the queue. The fuel cell stack12can then be restarted and enter net zero power mode.

One such scenario is a queue of vehicles at a stop sign. The controller22detects the queue of vehicles by using a combination of sensors24such as cameras, LIDAR, and radar. These sensors24provide the controller22with real-time information about the environment, including the position and speed of nearby vehicles. The controller22then processes this information to determine if there is a queue of vehicles at the stop sign. If so, the fuel cell stack12can be kept shut down until the vehicle10reaches the front of the queue. The fuel cell stack12can then be restarted and enter net zero power mode. If the vehicle10is in net zero power mode and is in a queue but not at the front of queue, the traction battery16can provide the electric machine18with power.

A second scenario is when the controller22detects a short stop at a traffic light by using a combination of various inputs to make this determination. The controller22takes into account the geographic location of the vehicle10, as well as information from the traffic light itself. The light may be equipped with sensors that detect the presence of vehicles and communicate this information to the controller22. The controller22also receives information from a traffic network, which includes data on traffic flow, road conditions, and other relevant information. In addition, the controller22uses information about the movement of other vehicles10at the intersection to make an informed decision about the length of the stop.

The vehicle controller22can be equipped with the sensors24such as navigation technologies to detect a short stop at a drive-thru by analyzing multiple factors such as geographic location30, information from the traffic network, historical vehicle data, and surrounding environmental conditions. For example, if the controller22determines that the vehicle10is located near a known drive-thru establishment based on its GPS coordinates30, it can cross-reference this information with real-time traffic data to identify any potential traffic slowdowns or bottlenecks at the drive-thru. Additionally, the controller22can access historical data from previous vehicles that have gone through the same drive-thru to estimate wait times and adjust its navigation route accordingly. By combining all of these sources of information, the vehicle controller22can make a highly informed decision about whether to enter the drive-thru or seek alternative routes to reach its destination.

The vehicle controller22can be equipped with various sensors24such as vehicle sensors and detect a short stop due to heavy traffic. The controller22uses geographic location data30to determine the current road conditions and traffic flow in the area. It also receives information from the traffic network, including real-time traffic updates, to identify any bottlenecks or slowdowns. Additionally, the controller22can take into account historical vehicle data, such as previous traffic patterns at the same time and location, to predict the current traffic situation. By combining all of this information, the vehicle controller22can accurately determine when the vehicle10is stopped in heavy traffic and adjust its actions accordingly. The vehicle controller22can also accurately determine when the vehicle10is in a queue or line of other vehicles.

Referring toFIG.2, at decision block40it is determined whether a stop-and-go driving scenario is detected. A line up of vehicles, or a queue, can cause a stop-and-go scenario as the vehicle progresses through the queue until it is first in the queue. These situations can be detected using standard techniques based on data received from a cloud server via a transceiver and with the assistance of a drive horizon module42. Brake and pedal usage information can be examined, for example, to determine whether the same are being alternately pressed a certain number of times during a predefined time period. Location information can be examined to determine whether the vehicle is near a traffic stop such as a stop sign, stop light, drive thru, in heavy traffic, or a number of other driving scenarios. If the result of decision block40is NO, the algorithm proceeds to operation44in which the fuel cell system continues to operate as normal. The normal operation may be a full run mode, where the fuel cell system can provide power to an electric machine or a traction battery.

If stop-and-go driving is detected, and the result of decision block40is YES, the algorithm proceeds to decision block46. In block46it is determined whether the fuel cell system is shut down using standard sensors and feedback data. If the result of decision block46is YES, the algorithm proceeds to operation48in which the fuel cell system stays in shut down mode. At decision block50, it is determined whether the driver is expected to drive away using standard techniques. Data indicating the driver has removed their foot from the brake pedal can be used as a trigger condition indicating the driver is expected to drive away. Vehicle to infrastructure data, and other data, can also be used to determine whether the driver is expected to drive away. If the data is indicating that the vehicle is finally first in a queue at a stop sign, it can be determined that the driver is expected to drive away. If the result of decision block50is YES, the algorithm proceeds to operation52in which the fuel cell system transitions to net zero power mode. In net zero mode, the fuel cell stack system may not produce enough power to supply other vehicle systems but may keep the fuel cell system ready to produce full power. If the result of decision block50is NO, the algorithm returns to operation48and the fuel cell stays shut down until drive away is expected.

If the result of operation46is NO, the algorithm proceeds to operation54in which the fuel cell system transitions to net zero power mode and operates the vehicle with traction battery power only. At decision block56, it is determined whether the stop-and-go driving scenario has cleared, for example, using the standard techniques and data mentioned above. If the result of decision block56is NO, the algorithm returns to operation54. If the result of decision block56is YES, the algorithm proceeds to operation58in which the fuel cell system exits net zero power mode and operates in full run mode. In full run mode the fuel cell system produces enough power to supply other systems of the vehicle.

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 may be made without departing from the spirit and scope of the disclosure.

The algorithms, methods, or processes disclosed herein can be deliverable to or implemented by a computer, controller, or processing device, which can include any dedicated electronic control unit or programmable electronic control unit. Similarly, the algorithms, methods, or processes can be stored as data and instructions executable by a computer or controller in many forms including, but not limited to, information permanently stored on non-writable storage media such as read only memory devices and information alterably stored on writeable storage media such as compact discs, random access memory devices, or other magnetic and optical media. The algorithms, methods, or processes can also be implemented in software executable objects. Alternatively, the algorithms, methods, or processes can be embodied in whole or in part using 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.