Traction motor optimizing system for forklift vehicles

A method for optimizing a dc motor having separately excited armature and field windings, the steps comprising:

• a) reading a signal representative of desired motor speed;
• b) reading signals representative of actual motor speed, armature current and field current;
• c) providing a feedback controller for generating an optimal armature current to field current ratio;
• d) computing optimal field current control effort as a function of signals representative of said armature current and said optimal armature current to field current ratio;
• and
• e) computing optimal armature voltage control effort as a function of signals representative of said desired motor speed and said actual motor speed.

A dc motor control system for separately exciting armature and field windings of a dc motor, comprising:

• a) a dc motor;
• b) sensing means operatively connected to said dc motor for providing signals representative of actual motor speed, armature current and field current;
• c) a feedback controller operatively connected to said sensing means for computing an optimal armature current to field current ratio and generating a signal representative of said ratio;
• d) reference signal means operatively connected to said dc motor for generating a signal representative of a desired motor speed;
• e) first computation means operatively connected to said feedback controller and said sensing means for computing optimal field current control effort as a function of said signals representative of armature current and representative of said optimal armature current to field current ratio;
• and
• f) second computation means operatively connected to said feedback controller, said dc motor, said reference signal means and said sensing means for computing optimal armature voltage control effort as a function of said signals representative of said desired motor speed and representative of said actual motor speed.