Classification of coreless motors

1. Classification of coreless motors

Hollow cup motors are divided into two types: brushed and brushless. The rotor of the brushed hollow cup motor has no iron core, and the stator of the brushless hollow cup motor has no iron core.

The brushed hollow cup is a motor with a wire cup plus a commutator as the rotor, and the brushless hollow cup is a structure with a wire cup as the stator and a permanent magnet as the rotor.

2. The difference between brushed motors and brushless motors

1. Brushed motors

The brushed motor uses mechanical commutation, the magnetic poles do not move, and the coil rotates. When the motor is working, the coil and commutator rotate, the magnet and carbon brush do not rotate, and the alternating change of the coil current direction is completed by the commutator and brushes that rotate with the motor.

In a brushed motor, the process is to arrange the two power input ends of each group of coils in a ring in sequence, separated by insulating materials, to form a cylinder-like thing, which is connected to the motor shaft. The power is passed through two small pillars made of carbon elements (carbon brushes). Under the action of spring pressure, from two specific fixed positions, it presses on two points on the ring-shaped cylinder where the power input of the coil is input, and energizes a group of coils.

As the motor rotates, different coils or different poles of the same coil are energized at different times, so that the N-S poles of the magnetic field generated by the coil have a suitable angle difference with the N-S poles of the nearest permanent magnet stator. The magnetic fields attract each other and repel each other, generating force to drive the motor to rotate. The carbon electrode slides on the coil terminal, like a brush brushing on the surface of an object, so it is called a carbon "brush".

Sliding against each other will rub the carbon brush, causing loss, and the carbon brush needs to be replaced regularly; the carbon brush and the coil terminal are alternately turned on and off, sparks will occur, electromagnetic damage will be generated, and electronic equipment will be interfered.

2. Brushless motor

Brushless motors use electronic commutation, the coil does not move, and the magnetic poles rotate. Brushless motors use a set of electronic devices to sense the position of the permanent magnet magnetic poles through Hall elements. Based on this perception, electronic circuits are used to switch the direction of the current in the coil in a timely manner to ensure that the magnetic force in the correct direction is generated to drive the motor. The shortcomings of brushed motors are eliminated.

These circuits are motor controllers. The controller of a brushless motor can also achieve some functions that brushed motors cannot achieve, such as adjusting the power switching angle, braking the motor, reversing the motor, locking the motor, and using the brake signal to stop powering the motor. The electronic alarm lock of electric vehicles now makes full use of these functions.

The brushless DC motor consists of a motor body and a driver, and is a typical mechatronics product. Since the brushless DC motor is operated in an automatic control mode, it will not add a starting winding to the rotor like a synchronous motor that starts under heavy load under variable frequency speed regulation, nor will it produce oscillation and loss of step when the load changes suddenly.