1) The brushless DC motors are the motors in which too many AC synchronous configurations are possible and in this semiconductor control is used for managing or controlling the stator current in such a way to obtain the maximum torque at an specific or given speed.
2) The construction of BLDC motor is shown below and which is similar to that of the permanent magnet synchronous motor.
1) The stator used in the core is an three phase winding and rotor is acting as an permanent magnet.
2) This is also consist of the rotor sensors in the design which produces the electrical signals that will indicate the current position of the motor.
3) The stator winding of this type of motor is driven from an electronic drive which is basically an transistorised three phase invertor.
4) The base driving signals of the transistors are achieved from the rotor position sensor which are connected in three phase mode.
5) The speed of such type motor is controlled by the controlling the stator voltage which can be achieved by controlling the DC input voltage of the invertor.
6) There are some matching things or we can say similarities in between the Permanent magnet synchronous motor and DC motors hence these are called as BLDC motors.
a. The driver circuit operates on DC supply.
b. The field produced by stator and rotor will remains stationary w.r.t. each other.
c. The torque speed characteristics are same as DC motors.
d. This are not having brushes while constructing the design.
The permanent magnet brushless DC motors will use the Hall sensors with 60 degree electrical spacing as shown in fig. These type of sensors will produce logic 1 when it will come in contact with pole N of the rotor otherwise logic 0
These type of motor are classified in two types as:
1) Unipolar half wave BLDC motor.
2) Bipolar Full wave BLDC motor.