pic: Kit Transmission Upgrade kit

[Paul Copioli]

Guys,

The fact that the torques are different than each other at 40 amps doesn't matter at all.

Think of it this way, as Dr. Joe always says: The two motors are combined to act as one motor. The motors force each other to run the same speed. If the motors are matched at free speed, then each motor contributes 0 N-m of torque at the combined gearbox free speed. If the motors are matched at a lower speed than free speed, then the slower motor has the possibility of being overrun by the faster motor and will contribute negative torque (a generator). The faster motor will contribute a positive torque equal to the slower motor's negative torque, thus having 0 torque at free speed. The motors will find equilibrium, but each motor may draw different current values ... who cares?

All of this can be calculated from the torque vs. speed and current vs. speed curves. Don't get hung up on the different current draws from each motor.

I match free speed ... why? Because it is easy to do, but you can match at any speed you want to. Remember, though, the small CIM has more power (notice I didn't say torque) than the larger one.

-Paul