FOUR-WHEEL DRIVEN VEHICLE

PROBLEM TO BE SOLVED: To drive either front wheels or rear wheels by an engine while driving the other by a motor, and to rectify the AC voltage of a power generator to be driven by an engine, and to prevent the damage of an inverter due to an overvoltage when controlling an AC voltage to a motor through PWM control by the invertor. SOLUTION: When it is determined that an input voltage to an invertor 10 is equal to or larger than an upper limit value, the voltage modulation of the PWM control of the invertor 10 is changed so that an input voltage to the invertor 10 can be suppressed. An AC voltage which is larger than an AC voltage adapted to the driving of a vehicle is commanded so that the pulse width of PWM control can be increased, and output currents to a motor 4 are increased (torque variation permission overvoltage protection processing), and simultaneously the phase of PWM control is adjusted so that the torque of the motor 4 can be prevented from being increased (torque fixed overvoltage protection processing). The overvoltage to the invertor 10 is predicted based on an engine revolving speed due to the slip, upshift, and idling of engine driving wheels. COPYRIGHT: (C)2009,JPO&INPIT