Brushed DC Motor Basics VII

  A compound wound brushed DC motor is a combination of both the shunt wound and series wound brushed DC motors. As you can see, the total current in the motor is the sum of the currents through the shunt field and the series field coils. The current through the series field coil is the same as the current through the rotor field. So, as a load is placed on the motor, the current through the rotor and series fields will increase. Thus, the current through the shunt field will decrease, the speed of the motor will decrease, and the motor torque will increase.

Compound-Wound (CWDC)

● Has the performance properties of both SHWDC and SWDC motors
● High torque at low speed w/ heavy loads, SWDC motors
● Great speed control, SHWDC motors
● Great for Industrial and automotive applications, example: generators
● Motor Runaway, less likely b/c shunt current must go to zero and series field must short
● More expensive than PMDC, SHWDC, and SWDC

  The compound wound brushed DC motor has the performance characteristics of both the shunt wound and the series wound brushed DC motors. It has the high torque at low speeds with heavy loads as seen with series wound brushed DC motors and has great speed control as with the shunt wound brushed DC motors. Compound wound brushed DC motors are great for industrial and automotive applications such as generators. With compound wound brushed DC motors the problem of motor runaway is less likely because the shunt current must go to zero and the series field must be shorted, thus the chances of both of these conditions occurring at the same time or very small. However, a compound wound brushed DC motor is more expensive than a permanent magnet, shunt wound, or a series wound brushed DC motors.