Mechatronics presentation Topic: DC motor Guide Prof. S.S Balpande Presented by: Krishna Chandak

DC motor A DC motor is any of a class of rotary electrical machines that converts direct current electrical energy into mechanical energy.

Types of dc motors Brushed DC Motor Brushless DC Motor DC Series DC Shunt Brushless DC Motor

Brushed DC Motor The simplest type of motor is the brushed DC motor. In this type of motor, electrical current is passed through coils that are arranged within a fixed magnetic field. The current generates magnetic fields in the coils; this causes the coil assembly to rotate, as each coil is pushed away from the like pole and pulled toward the unlike pole of the fixed field. To maintain rotation, it is necessary to continually reverse the current—so that coil polarities will continually flip, causing the coils to continue “chasing” the unlike fixed poles

No contact in between B1 and S1 and even B2 and S2 . S2 No contact in between B1 and S1 and even B2 and S2   the circuit breaks

due to inertia of rotational motion the coil does not stop suddenly and rotates further.

SERIES AND SHUNT In series dc motor, the field winding is connected in series with the armature in which high starting torque(high current) is there but with time it decreases. In shunt dc motor, the field winding is connected in parallel with the armature in which constant torque is there which remains constant throughout in ideal case.

Series motor have series winding and thus a high armature current is same as field current. Series DC Motor is used where High starting torque required. Shunt winding are parallel and hence have low current. Shunt DC Motor is used in Constant Torque Application.

BRUSHLESS DC MOTOR Typical brushless DC motors use one or more permanent magnets in the rotor and electromagnets on the motor housing for the stator. A motor controller converts DC to AC. This design is mechanically simpler than that of brushed motors because it eliminates the complication of transferring power from outside the motor to the spinning rotor. 

WORKING With brushed motors, the brushes deliver current through the commutator into the coils on the rotor. So how does a brushless motor pass current to the rotor coils? It doesn’t—because the coils are not located on the rotor. Instead, the rotor is a permanent magnet; the coils do not rotate, but are instead fixed in place on the stator. Because the coils do not move, there is no need for brushes and a commutator.

Advantages of brushless motors include long life span, little or no maintenance, and high efficiency. Disadvantages include high initial cost, and more complicated motor speed controllers. 

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