How does a dc motor work?
The DC motor is a machine that transforms electric energy into mechanical energy in form of rotation. Its movement is produced by the physical behavior of electromagnetism. DC motor have inductors inside, which produce the magnetic field used to generate movement. But how does this magnetic field changes if DC current is being used? 
An electromagnet, which is a piece of iron wrapped with a wire coil that has voltage applied in its terminals. If two fixed magnets are added in both sides of this electromagnet, the repulsive and attractive forces will produce a torque. 
Then, there are two problems to solve: feeding the current to the rotating electromagnet without the wires getting twisted, and changing the direction of the current at the appropriate time. Both of these problems are solved using two devices: a split-ring commutator, and a pair of brushes. 
As it can be seen, the commutator has two segments which are connected to each terminal of the electromagnet, besides the two arrows are the brushes which apply electric current to the rotary electromagnet. In real vibration motor DC motors it can be found three slots instead of two and two brushes.
This way, as the electromagnet is moving its polarity is changing and the shaft may keep rotating. Even if it is simple and sounds that it will work great there are some issues which make these motors energy inefficient and mechanically unstable, the principal problem is due to the timing between each polarity inversion. Since polarity in the electromagnet is changed mechanically, at some velocities polarity is changing too soon, which result in reverse impulses and sometimes in changing too late, generating instantaneous “stops” in rotation. Whatever the case, these issues produce current peaks and mechanical instability.
Established in 2007, Leader Microelectronics (Huizhou) Co., Ltd. is an international enterprise integrating R & D, production and sales. We mainly produce flat motor, linear motor, BLDC motor, coreless motor, SMD motor, Air-modeling motor, deceleration motor and so on, as well as micro motor in multi-field application.
Post time: Aug-15-2018
