Patent ID: 7863837

Claim:
A drive system for an electrically driven dump truck comprising: a prime mover; an electronic governor for controlling the revolution speed and torque of the prime mover; an alternating-current generator driven by the prime mover; prime mover loads other than the alternating-current generator, driven by the prime mover; at least two electric motors for traveling, each of which is driven by the electric power supplied by the alternating-current generator; and at least two inverters, each of which is connected to the alternating-current generator, and each of which controls each of the electric motors, wherein the drive system comprises target revolution speed calculation means for calculating the target revolution speed corresponding to the operation amount of an accelerator pedal, and motor control means for controlling the inverters to control the electric motors in response to the operation amount of the accelerator pedal; the electronic governor is configured to control the fuel injection amount for the prime mover on the basis of the target revolution speed and is set such that when the target revolution speed is set at least at the maximum revolution speed, the control of the fuel injection amount becomes a droop control; and the motor control means includes: first target motor horsepower calculation means for calculating a first target motor horsepower corresponding to the operation amount of the accelerator pedal; second target motor horsepower calculation means including speed sensing control means for modifying an available maximum horsepower for the electric motors for traveling such that the available maximum horsepower increases when the actual revolution speed of the prime mover is higher than the target revolution speed, and the increased maximum horsepower decreases with the decrease in the actual revolution speed of the prime mover, said second target motor horsepower calculation means for determining, as a second target motor horsepower, the available maximum horsepower that has been modified by the speed sensing control means; target motor horsepower limiting means for limiting the first target motor horsepower so that the first target motor horsepower does not exceed the second target motor horsepower, thereby to generate a third target motor horsepower; and inverter control means for determining a first target motor torque of each of the two electric motors on the basis of the third target motor horsepower, thereby to control the inverters.