mechanically coupled DC motors

Hi all,

I am building a DC motor control demonstration panel. Apart from controlling the speed I also want to simulate variable load acting on the DC motor. Hence I thought of coupling another DC motor to the existing one and rotating it in the opposite direction just like in the figure.

If we say that motor A is the motor to be controlled (clockwise) and B is the torque generator, even though B is given power to rotate anti clockwise it will always be rotating in the opposite direction (because of A). This will cause B to heat up and I fear that it would get burnt.

The goal is to somehow dissipate the current generated by B. Can you all help me.

BTW both motors will be driven by H-bridges and both will have speed measuring ability.

Thank you !!!!!!!!!!!!!!

mo.JPG

I have used a similar set-up in the past to determine drive motor performance. The driven motor (generator) should not be reverse driven since you will have no effective way of determining the actual torque applied to either motor. Your best bet is to simply load the generator motor with resistors (halogen lamps are quite effective). You can then measure the voltage and current supplied to the load and determine the electrical output of the generator. The more electrical load you apply, the greater torque that has to be supplied by the driver motor. My measuring both driver and driven voltage and current you can determine system losses and hence determine the efficiency of the driver motor.