Patent ID: 6953100

Claim:
A method to regulate a supply of energy to an electric motor from a hybrid energy supply system that comprises at least one fuel cell, at least one energy storage buffer, a bi-directional converter electrically coupled between the fuel cell and the energy storage buffer, and a DC/DC converter electrically coupled between the bi-directional converter and the energy storage buffer, the method comprising: producing a vehicle current request value based at least in part on a detected position of a throttle; determining an output voltage of the fuel cell; in a first operating mode, current controlling the DC/DC converter if the output voltage of the fuel cell is between an upper limit value and a lower limit value so that the current supplied to the electric motor by the fuel cell is approximately equal to the vehicle current request value; voltage controlling the DC/DC converter if the output voltage of the fuel cell is at or below the lower limit value to raise the output voltage of the fuel cell to a level of at least the lower limit value, and voltage controlling the DC/DC converter if the output voltage of the fuel cell is at or above the upper limit value to lower the output voltage of the fuel cell, to a level not greater than the upper limit value.