Abstract: A system and a method that provides fuel cell and energy storage hybrid-electric propulsion and control for a heavy-duty vehicle over 10,000 pounds GVWR. Power output is supplied from a fuel cell system to a high-power intermediate DC bus through a fuel cell DC/DC converter. Power output is supplied from an energy storage system to the high-power intermediate DC bus through a separate energy storage fuel cell DC/DC converter. The received power is combined on the high-power intermediate DC bus to create a stable voltage. The stable voltage from the high-power intermediate DC bus is supplied to one or more electric motors/generators to accelerate the heavy duty vehicle.

Abstract: A reverse current protection device includes one or more contactors in a power circuit that open to prevent current flow and close to allow current flow; an impedance buffer to invert voltage across the diode; a threshold detector to compare inverted voltage to a reference voltage to determine a good or fault diode condition; an opto-isolator actuatable by the threshold detector when at least one of a good diode condition is determined and a fault diode condition is determined; and a relay in communication with the opto-isolator to cause at least one of the one or more contantors to close in a good diode condition and open in a fault diode condition.

Abstract: A reverse current protection device for a fuel cell of a power circuit protects the fuel cell from damage caused by reverse current into the fuel cell caused by a faulty diode. The reverse current protection device includes a contactor for opening the power circuit to prevent current from flowing therethrough and for closing the power circuit to allow current to flow therethrough, means for measuring the voltage across the diode to determine if the diode is in a good condition or a fault condition, means for causing the contactor to be closed if the diode is in a good condition and open if the diode is in a fault condition so that current does not flow through the contactor, protecting the fuel cell from damage caused by reverse current through the diode and into the fuel cell.