Patent ID: 7626354

Claim:
A hybrid vehicle comprising: an engine; first and second motor generators arranged to generate electricity by being driven either by the engine or from regeneration of kinetic energy; a power supply line that electrically connects the first motor generator with the second motor generator; a battery configured to change a voltage of the battery in steps and connected via a switch to the electric power supply line; and a variable voltage control configured to adjust an output of at least one of the first and second motor generators before opening the switch such that a charge/discharge current of the battery approaches zero, to open the switch to change the voltage of the battery in response to adjusting the output of at least one of the first and second motor generators, and to modify an output of the engine based on an amount of change made in the voltage of the battery in response to opening the switch, with the variable voltage control being further configured to close the switch after minimizing a voltage difference between a voltage of the power supply line and the voltage of the battery by adjusting an output of at least one of the first and second motor generators.