Motor drive apparatus for electric forklift and electric forklift adopting the same

A motor drive apparatus of an electric forklift which is mounted on the electric forklift and controls a first traveling motor and a second traveling motor, respectively transmitting power to a left drive wheel and a right drive wheel of the electric forklift based on a speed command value showing a target speed of the electric forklift, the apparatus comprising:

• a first torque command value generation unit and a second torque command value generation unit that are respectively provided in the first traveling motor and the second traveling motor, each of which generates a torque command value indicating torque of the corresponding traveling motor in response to a gap between a speed command value of the corresponding traveling motor and a speed detection value that is a current speed of the corresponding traveling motor;
• and
• a first slip detector and a second slip detector that are respectively provided in the first traveling motor and the second traveling motor, each of which generates a slip ratio estimation value showing a slip state of the corresponding drive wheel based on the speed detection value of the corresponding traveling motor and the torque command value of the corresponding traveling motor,
• wherein each of the first slip detector and the second slip detector includes a first arithmetic unit which generates an inertial force estimation value proportional to a differential value of the speed detection value of the corresponding traveling motor and a second arithmetic unit which generates the slip ratio estimation value in response to a relationship between the corresponding inertial force estimation value and the torque command value of the corresponding traveling motor.