Abstract: Systems and methods are provided for regulating the state of charge of a battery. An exemplary electrical system includes a fuel cell coupled to a bus and a battery coupled to the bus via a switching arrangement coupled to a capacitor. An exemplary method for operating the electrical system involves operating the switching arrangement such that a voltage of the battery is substantially equal to a voltage of the fuel cell when a state of charge of the battery is greater than a lower threshold value and less than an upper threshold value, and operating the switching arrangement to couple the capacitor electrically in series between the battery and the bus when the state of charge of the battery is not between the lower threshold value and the upper threshold value.

Abstract: A heating system for optimizing execution of heating tasks in a fuel cell vehicle is disclosed, the system including a stack coolant loop with a fuel cell stack, a primary pump, and a radiator module. A bypass coolant loop is disposed parallel with and is connected to the stack coolant loop between the fuel cell stack and the radiator module. The bypass loop including a cabin heat exchanger and a coolant heater, along with a secondary pump for pumping coolant through the heaters when desired.

Abstract: A system and method for managing power flow in a fuel cell vehicle. The method provides a difference between a power limit signal and an actual power signal to a PI controller to generate a power offset signal. The method determines whether a fuel cell stack is able to provide enough power to satisfy a power request, and if so, adds the power request and the power offset signal to generate a stack power request signal to cause the upper power limit signal to move towards and be matched to the actual power signal. If the stack is not able to provide enough power to satisfy the load power request signal, the method subtracts the power offset signal from the power limit signal to provide a load limit signal to cause the actual stack power signal to move towards and be matched to the upper power limit signal.

Abstract: Systems and methods are provided for regulating the state of charge of a battery. An exemplary electrical system includes a fuel cell coupled to a bus and a battery coupled to the bus via a switching arrangement coupled to a capacitor. An exemplary method for operating the electrical system involves operating the switching arrangement such that a voltage of the battery is substantially equal to a voltage of the fuel cell when a state of charge of the battery is greater than a lower threshold value and less than an upper threshold value, and operating the switching arrangement to couple the capacitor electrically in series between the battery and the bus when the state of charge of the battery is not between the lower threshold value and the upper threshold value.

Abstract: A method of controlling the ventilation system for an energy source in a fuel cell vehicle is disclosed, which includes an HVAC system, a fluid reserve, and a rechargeable energy storage system (RESS), capable of controlling a temperature of the RESS to militate against damage to or a shortened life of the battery, while maximizing vehicle durability, efficiency, performance, and passenger comfort.

Abstract: Systems and methods are provided for regulating the state of charge of a battery. An exemplary electrical system includes a fuel cell coupled to a bus and a battery coupled to the bus via a switching arrangement coupled to a capacitor. An exemplary method for operating the electrical system involves operating the switching arrangement such that a voltage of the battery is substantially equal to a voltage of the fuel cell when a state of charge of the battery is greater than a lower threshold value and less than an upper threshold value, and operating the switching arrangement to couple the capacitor electrically in series between the battery and the bus when the state of charge of the battery is not between the lower threshold value and the upper threshold value.

Abstract: A system and method for managing power flow in a fuel cell vehicle. The method provides a difference between a power limit signal and an actual power signal to a PI controller to generate a power offset signal. The method determines whether a fuel cell stack is able to provide enough power to satisfy a power request, and if so, adds the power request and the power offset signal to generate a stack power request signal to cause the upper power limit signal to move towards and be matched to the actual power signal. If the stack is not able to provide enough power to satisfy the load power request signal, the method subtracts the power offset signal from the power limit signal to provide a load limit signal to cause the actual stack power signal to move towards and be matched to the upper power limit signal.

Abstract: A system and method for controlling the voltage on a high voltage bus in a fuel cell system in response to a failed high voltage battery. The method includes determining if the high voltage battery has failed, and disconnecting the battery from the high voltage bus in response to a failure. The method measures the voltage of the fuel cell stack by a DC boost circuit and converts the measured voltage to a voltage set-point value that sets the voltage on the high voltage bus, where the voltage set-point value changes as the measured voltage changes. A supervisory controller sets the media flow to the fuel cell stack and determines a minimum stack voltage limit value based on the stack maximum current draw that is used to determine a high voltage bus lower limit value.

Abstract: A method of controlling the ventilation system for an energy source in a fuel cell vehicle is disclosed, which includes an HVAC system, a fluid reserve, and a rechargeable energy storage system (RESS), capable of controlling a temperature of the RESS to militate against damage to or a shortened life of the battery, while maximizing vehicle durability, efficiency, performance, and passenger comfort.

Abstract: A method for gathering information from battery sensors—for instance, information regarding the state-of-charge (SOC), temperature and/or other characteristics of battery cells in a vehicle battery pack—and using that information to estimate or predict battery degradation or state-of-health (SOH). According to an exemplary embodiment, the method uses both a time-based algorithm and an event-based algorithm to predict or estimate battery degradation. The event-based algorithm may select certain data from the battery conditions (e.g., a state-of-charge (SOC) swing (?SOC) or an SOC maximum (SOCMax)), instead of using the entire set of battery condition data, and may use this information in its prediction or estimate.

Abstract: A system for reducing oscillations on a high voltage bus. The system includes a high voltage battery electrically coupled to the high voltage bus and a DC/DC boost converter electrically coupled to the high voltage bus and a fuel cell stack. The DC/DC converter includes a current controller that selectively controls the current provided by the fuel cell stack. A system controller provides a stack current set-point to the DC/DC converter. The DC/DC converter includes a voltage device that receives a voltage signal from the bus and provides a time derivative of the voltage signal that defines voltage changes on the bus over time. The time derivative signal is provided to a summer that adjusts the current stack set-point to provide a modified current set-point to the current controller that selectively adjusts the current provided by the fuel cell stack to dampen oscillations on the high voltage bus.

Abstract: A method and system for controlling temperature in an electric vehicle battery pack such that battery pack longevity is preserved, while vehicle driving range is maximized. A controller prescribes a maximum allowable temperature in the battery pack as a function of state of charge, reflecting evidence that lithium-ion battery pack temperatures can be allowed to increase as state of charge decreases, without having a detrimental effect on battery pack life. During vehicle driving, battery pack temperature is allowed to increase with decreasing state of charge, and a cooling system is only used as necessary to maintain temperature beneath the increasing maximum level. The decreased usage of the cooling system reduces energy consumption and increases vehicle driving range. During charging operations, the cooling system must remove enough heat from the battery pack to maintain temperatures below a decreasing maximum, but this has no impact on driving range.

Abstract: A system for cooling a fuel cell stack and a drive unit in a fuel cell vehicle is disclosed, wherein the system includes a drive unit and a fuel cell stack. An oil cooling loop for the drive unit includes a three way valve, a liquid to liquid heat exchanger, and a pump. The liquid to liquid heat exchanger may be used to transfer drive unit off heat into the stack coolant loop. By not using an oil to air heat exchanger overall heat exchanger arrangement air side pressure drop can be minimized and airflow increased. The three way valve allows decoupling of the cooling loops if needed to inhibit negative impact on the fuel cell stack.

Abstract: Systems and methods are provided for regulating the state of charge of a battery. An exemplary electrical system includes a fuel cell coupled to a bus and a battery coupled to the bus via a switching arrangement coupled to a capacitor. An exemplary method for operating the electrical system involves operating the switching arrangement such that a voltage of the battery is substantially equal to a voltage of the fuel cell when a state of charge of the battery is greater than a lower threshold value and less than an upper threshold value, and operating the switching arrangement to couple the capacitor electrically in series between the battery and the bus when the state of charge of the battery is not between the lower threshold value and the upper threshold value.

Abstract: A fuel cell system and method for controlling relative humidity in a fuel cell system. A controller can be signally coupled to one or more sensors and configured to operate at least one flow manipulation device in response to changes in a relative humidity of a reactant passing through the cathode flowpath of the fuel cell in order to maintain the relative humidity within a prescribed range. The controller correlates one or more of a temperature setpoint, pressure setpoint, stoichiometry setpoint or actual operating condition of any of them to an operating condition of the system. In this way, a desired level of relative humidity can be achieved, maintained or both while minimizing the use of power-robbing flow manipulation devices, such as a pump, compressor, fan or related component.

Abstract: A method and system for controlling temperature in an electric vehicle battery pack such that battery pack longevity is preserved, while vehicle driving range is maximized. A controller prescribes a maximum allowable temperature in the battery pack as a function of state of charge, reflecting evidence that lithium-ion battery pack temperatures can be allowed to increase as state of charge decreases, without having a detrimental effect on battery pack life. During vehicle driving, battery pack temperature is allowed to increase with decreasing state of charge, and a cooling system is only used as necessary to maintain temperature beneath the increasing maximum level. The decreased usage of the cooling system reduces energy consumption and increases vehicle driving range. During charging operations, the cooling system must remove enough heat from the battery pack to maintain temperatures below a decreasing maximum, but this has no impact on driving range.

Abstract: A system and method for controlling the voltage on a high voltage bus in a fuel cell system in response to a failed high voltage battery. The method includes determining if the high voltage battery has failed, and disconnecting the battery from the high voltage bus in response to a failure. The method measures the voltage of the fuel cell stack by a DC boost circuit and converts the measured voltage to a voltage set-point value that sets the voltage on the high voltage bus, where the voltage set-point value changes as the measured voltage changes. A supervisory controller sets the media flow to the fuel cell stack and determines a minimum stack voltage limit value based on the stack maximum current draw that is used to determine a high voltage bus lower limit value.

Abstract: A fuel cell system that does not include a high voltage battery in combination with a fuel cell stack. The fuel cell stack and a bi-directional power module are electrically coupled to a high voltage bus. A first larger capacity 12 volt battery is electrically coupled to the power module opposite to the high voltage bus and a second smaller capacity 12 volt battery is electrically coupled to the first 12 volt battery, where a diode is electrically coupled between the first and second 12 volt batteries and only allows current flow from the first 12 volt battery to the second 12 volt battery. 12 volt battery loads are electrically coupled to the second 12 volt battery.

Abstract: A system for reducing oscillations on a high voltage bus. The system includes a high voltage battery electrically coupled to the high voltage bus and a DC/DC boost converter electrically coupled to the high voltage bus and a fuel cell stack. The DC/DC converter includes a current controller that selectively controls the current provided by the fuel cell stack. A system controller provides a stack current set-point to the DC/DC converter. The DC/DC converter includes a voltage device that receives a voltage signal from the bus and provides a time derivative of the voltage signal that defines voltage changes on the bus over time. The time derivative signal is provided to a summer that adjusts the current stack set-point to provide a modified current set-point to the current controller that selectively adjusts the current provided by the fuel cell stack to dampen oscillations on the high voltage bus.

Abstract: An assembly (10) for achieving and maintaining a desired battery operating temperature. A positive thermal coefficient (PTC) resistive element (18) is disposed adjacent a battery (12) in a position to heat the battery.