Gm Global Technolgoy Operations, Inc.

Jochen Schaffnit

Peter Kilian

Oliver Maier

Volker Formanski

Jochen Lenz

Andreas Voigt

Sebastian Lienkamp

Peter Willimowski

A system and method are disclosed for using regenerative braking power to start a fuel cell stack for system restart during a start/stop operation of a fuel cell hybrid vehicle. The method includes disconnecting the fuel cell stack from a high voltage bus for the start/stop operation and using regenerative braking power provided by an electric traction system to recharge a battery in the hybrid vehicle during the start/stop operation. The method also includes reconnecting the fuel cell stack to the high voltage bus and providing at least some of the regenerative braking power from the electric traction system to a compressor that provides cathode air to the fuel cell stack when the stack is reconnected to the high voltage bus at the end of the start/stop operation. A bi-directional DC converter selectively distributes the power to the compressor and the battery.

Usage of regenerative brake power for system restart in start-stop operation of fuel cell hybrid vehicles

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.

Fuel cell power control by offset estimation

A power request controller that prevents a power request signal to a fuel cell stack controller from providing more compressor air and hydrogen gas than is necessary to meet the current power demands of the vehicle. The stack controller generates a signal of the available current from the fuel cell stack. This signal and the measured current actually being drawn from the stack are received by a proportional-integral (P-I) controller in the power request controller. If the available stack current is significantly greater than the stack current being used, the P-I controller will provide an output signal that reduces the power request signal to the stack controller so that the current produced by the stack and the current being drawn from the stack are substantially the same. A transient detector turns off the P-I controller so that it does not reduce the power request signal during an up-power transient.

Fuel cell power request control strategy

An electrical system for a fuel cell hybrid vehicle where the vehicle includes a fuel cell stack and a high voltage battery. A traditional bi-directional DC/DC power converter is provided in a high voltage bus that couples the fuel cell stack voltage and the battery voltage. Further, a traditional power inverter module is provided that converts the high voltage DC power signal on the high voltage bus to an AC signal suitable for an electric traction motor on the vehicle. The present invention proposes using the already existing bi-directional DC/DC power converter and the PIM as part of an electric power take out (EPTO) circuit that provides AC power for external vehicle loads while the fuel cell stack and battery are not being used to power the vehicle.

Low cost electric power take out functionality for fuel cell hybrid vehicles

Vehicular electrical systems are provided. The vehicular electrical systems include a first direct current (DC) voltage supply, a second DC voltage supply coupled to the first DC voltage supply, a first direct current-to-direct current (DC/DC) power converter coupled to the first and second DC voltage supplies, a second DC/DC power converter coupled to first and second DC voltage supplies and the first DC/DC power converter, and a power receptacle electrically connected to the second DC/DC power converter. The second DC/DC power converter is configured to regulate power flow between the first and second voltage supplies and the power receptacle.

Vehicular electrical systems

A system and method for equalizing the state of charge of the cells of a battery in an electric vehicle while the vehicle is being driven. The method includes monitoring the state of charge of the battery cells in the battery and measuring the actual current of the battery. The method also includes determining a maximum charge current limit of the battery and comparing the actual battery current and the charge current limit. The method also includes modifying the charge current limit based on the comparison between the actual battery current and the charge current limit. The method then converts the modified charge current limit to a power charge limit and then over charges the battery using a small amount of current and the power charge limit so that all of the cells in the battery become fully charged.

Control strategy for HV battery equalization charge during driving operation in fuel cell hybrid vehicles

A system for controlling the power output of a fuel cell stack and a battery in a hybrid fuel cell system. The system includes a power damping filter that receives a power request signal, and damps the request to reduce large changes in the power request. A battery state of charge controller receives the difference between a battery state of charge set-point and the actual battery state of charge, and provides a battery power signal that attempts to maintain the battery state of charge at the set-point. The damped power signal and the battery power signal are added to generate a system power demand signal that satisfies the driver power request using the battery power and fuel cell stack power, and uses the fuel cell stack power to charge the battery during low power transients or if the battery state of charge is below the set-point.

System for controlling the power output of a fuel cell stack and battery

A fuel cell system employing a floating base load hybrid strategy for reducing fast voltage transients of a FCPM. A power request signal is applied to an average power calculation processor that calculates the average power requested over a predetermined previous period of time. A weighting function processor provides a weighting function based on the state of charge of an EESS. The power available from the FCPM and the EESS is applied to a power comparison processor. The available power is compared to the power request to provide a difference value between what is currently being provided and what is desired. The difference value is compared to power limit values of the EESS. The output value of this comparison is added to a filtered value to generate a signal for the change in the output power of the fuel cell stack based on the power request.

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Darmstadt, Germany

Jochen Schaffnit