Patent ID: 8635037

Claim:
A method of managing a state of charge of a battery in a hybrid electric power system comprising a fuel cell, the method comprising: defining a setpoint; calculating an estimated present state of charge of the battery according to the following equation: SOC ^ ⁡ ( k ) = SOC ^ ⁡ ( k - 1 ) + T s ⁡ [ - I battery ⁡ ( k ) C c ⁡ ( I b ) + L ⁡ ( V bus ⁡ ( k ) - V ^ bus ⁡ ( k ) ) ] wherein (k) is the estimated present state of charge of the battery; (k−1) is a previously estimated state of charge of the battery; T s is the time in seconds elapsed since the previously estimated state of charge of the battery was calculated; I battery (k) is the battery current; C c is the battery capacity in Ampere-second; L is an observer gain; V bus (k) is the battery voltage; and {circumflex over (V)} bus is an estimate of the battery voltage based on the previous state of charge estimate (k−1) and on the measured battery current I battery (k); and regulating the state of charge of the battery by manipulating a fuel cell current supplied from the fuel cell to the battery based on the difference between the setpoint and the estimated present state of charge of the battery.