# Pro & Cons of Series and compound wound motors



## major (Apr 4, 2008)

Hi tinkeringgreg,

If you plan to use a PWM motor controller stay away from compound wound motors and use a series motor. If you have some other control method in mind, a compound motor might fit the bill. Compound motors are often used in applications where the load can vary and some speed regulation is desired. The RPM of a series motor can vary greatly with load, especially at light loads. A compound winding will lessen the RPM difference as the load varies. And the compound motor will have a finite no-load speed whereas the series motor tends to overspeed as the load is removed.

Having said that, I do use a compound motor with a Curtis PWM on my 48V lawn tractor. Just simple to wire and the motor was a freebee. So it will work. But it is not the proper way. As the PWM goes to low motor voltage, the shunt part of the compound field disappears and offers no benefit. But on the other hand, at high PWM (high voltage/high RPM) the shunt field is there and would limit speed if the belt broke. Which has never happened in 14 years.

Another downside to compound motors is more complexity if you need to reverse rotation. Requires a 5 or 6 terminal motor.

Hope that helps,

major


----------

