Energy control method for fuel cell-electric double layer capacitor hybrid power source system

In our previous study, it is developed the method to smooth the output power of fuel cells (FCs) by combining with electrical double layer capacitors (EDLCs). This study proposes an energy control method to maintain the voltage of the EDLCs within the specified range and to reduce the fluctuation of the FC output power at the same time, using an additional PI control loop and a digital filter to gradually vary the reference value of the FC voltage. The control parameter is determined using the simplified numerical model that is also constructed. The simulation result obtained from the model that used the determined control values showed that the system works stable and the movement of the operating point of the FC is controlled under the load condition where the duty ratio of the square-wave load current is changed. Finally, in consideration of vehicle applications, simulations using the large scale model is demonstrated and its results are evaluated.