Gm Global Technolgoy Operations, Inc.

Scott Dewey

John Wheat

Bruce Jeffrey Clingerman

Rainer Pechtold

Victor W Logan

Clark G Hochgraf

Manfred Herrmann

David B Ouwerkerk

Bernhard Wnendt

Hermann Victor

Christian Kunstmann

Roland Nolte

A fuel cell system that employs a start-up heater. The heater is coupled to a cold plate that warms a stack coolant during system start-up. A heater circuit measures the voltage at the output of the fuel cell stack and across the heater and the current through the fuel cell stack and through the heater. The heater circuit controls the amount heat that the heater generates by the measured voltage and current and the available power at the output of the fuel cell stack. In one embodiment, the heater includes field effect transistors (FETs) and planar resistors directly mounted to the cold plate. The FETs operate in their linear mode, allowing only the amount of current, which is required at a given voltage, to produce the power needed from the stack.

FCPM freeze start heater

A fuel cell system that includes a fuel cell stack providing high voltage power. A tap is electrically coupled to the positive end of the stack to provide a positive voltage output terminal of the fuel cell stack, and a tap is electrically coupled to the negative end of the stack to provide a negative output terminal of the fuel cell stack. A low voltage tap is electrically coupled to one or more intermediate bipolar plates of the stack to provide low voltage power. Several intermediate taps can be electrically coupled to the bipolar plates, where a center intermediate tap is designated a reference potential tap. A switching network switches the several voltage potentials to provide an AC signal.

Low voltage power tap on high voltage stack

A mechanization of a fuel cell system and a method of operating the same is provided which simplifies the start-up of the fuel cell system. The fuel cell system can be started up without using any battery derived high voltage power to drive a high voltage compressor. The present invention provides for the use of a low voltage blower to provide oxygen to the cathode side of the fuel cell stack to enable start-up of the fuel cell stack without the initial use of a high voltage compressor. The low voltage blower can be powered by a low voltage power source and/or the voltage produced by the fuel cell stack.

Starting a fuel cell system using ambient air and a low voltage blower

A system for detecting an isolation fault in a multi-stack fuel cell system. The system determines the percentage of the voltage from each stack in the multi-stack that contributes to the voltage at a positive terminal and a negative terminal of the stack when a no-fault condition exists. The system then uses those percentages and the actual measured stack voltages to determine if a fault condition exists. The actual voltage measurement at the positive terminal is compared to the calculated voltage contribution from each stack at the positive terminal for the no-fault condition. Also, the actual voltage measurement at the negative terminal is compared to the calculated voltage contribution from each, stack at the negative terminal for the no-fault condition. If there is a significant enough different between the calculated voltage for a no-fault condition and the calculated percentage of the actual voltage measurements, than a fault condition exists.

Multi-stack isolation detection system

Growing community of inventors

Dansville, NY, United States of America

Scott Dewey