Fuel Cell Stack Voltage Control for Oxide Removal

The patent applies periodic low-voltage/high-power pulses during low-power operating modes to remove accumulated oxides from the catalyst surface. These pulses are delivered at specific intervals (e.g., every 10-60 seconds) and durations (e.g., 0.1-10 seconds) to reduce oxide coverage without significantly impacting overall stack efficiency. The periodic nature of these pulses allows the system to maintain high efficiency during normal operation while periodically cleaning the catalyst surface.

The patent changes the voltage parameter dynamically by switching between high-potential operation during normal conditions and low-voltage pulses during cleaning cycles. The voltage is modulated between a first level (during pulses) and a second level (between pulses), with the pulse duration and frequency adjusted based on operating conditions such as temperature, humidity, and load history. This parameter modulation enables oxide removal while minimizing impact on power performance.

The patent applies partial action by delivering low-voltage pulses for limited durations (0.1-10 seconds) at controlled frequencies during low-power modes. The pulse duty cycle is kept low (e.g., 1-10%) to remove oxides while minimizing disruption to the catalyst's power-generating capability. The action is excessive enough to reduce oxide coverage but controlled to avoid significant power performance degradation.

The patent implements dynamic control of pulse frequency, duration, and voltage levels based on real-time monitoring of stack conditions including temperature, humidity, load history, and estimated oxide coverage. The control strategy adapts pulse parameters to match operating conditions, increasing pulse frequency during extended low-power periods and reducing it when power performance is critical. This dynamic adjustment optimizes the balance between oxide removal and power maintenance.