The PM DC motor has some advantages over other types of DC motors. They do not require preparation for field excitation. No input power is consumed for excitation, which improves the efficiency of the DC motor. No field coil, so space is saved for the field coil, reducing the overall size of the motor. It is more economical and economical for fractional rated kW applications. In this case, the armature reaction of the DC motor cannot be compensated, so the magnetic field strength may weaken due to the demagnetizing effect of the armature reaction. During starting, reversing and overload condition of the motor, there is a possibility that the poles will be permanently or partially demagnetized due to excessive armature current. Another important disadvantage of the PMDC motor is that the field in the air gap is stable and limited, so it cannot be controlled externally. For this reason, it is difficult to realize efficient DC motor speed control for this type of motor. PMDC motor is widely used where small DC motors are needed and very effective control is not needed, such as in car starting, toys, windshield wipers, washing machines, blowers, air conditioners, computer disk drives and many others