Abstract: A fuel cell generation system employing a load following algorithm that provides the desired output power from the fuel cell on demand. The system includes a draw current sensor that measures the current drawn from the fuel cell used to satisfy the system load demands. The load following algorithm uses the measured draw current to identify the proper amount of fuel and air to meet the load demands, and then provides a buffer of extra fuel and air to the fuel cell so if the load demand suddenly increases, the fuel cell is able to immediately produce the extra output power. As the current drawn from the fuel cell changes in response to changing load demands, the load following algorithm causes the amount of fuel and air being applied to the fuel cell stack to increase and decrease so that the buffer of extra fuel and air is maintained substantially constant.

Abstract: A PSA unit for purifying hydrogen in a fuel processor system. The PSA unit employs rotary valves that cycle the pressurization of vessels, including an adsorbent, between a high pressure state and a low pressure state. The purified hydrogen is released from the vessels through a purified gas output port when the vessels are in the high pressure state and the impurities are released through an exhaust port when the vessels are in the low pressure state. The PSA unit also employs a mass flow control device and a pressure sensor in the purified gas output port. A controller receives a pressure signal from the pressure sensor, and controls the flow through the mass flow control device and the speed of the rotary valves so that the proper pressure is maintained at the hydrogen output port.

Abstract: Hydrogen in a fuel cell is vented and purged with a fail-closed valve using stored energy (e.g. from a capacitor) when a diagnostic parameter is outside of an acceptable operating range. The valve closes after the stored energy has depleted. A safety switch in the relay circuit of the solenoid switch (or solenoid valve) is also grounded in computer-implemented shutdowns. Benefits from the invention include use of air-compatible catalysts, minimized parasitic losses to power output, minimized contamination of fuel cell internal surfaces after venting, minimized risk of explosive mixture buildup, and efficient operation.