What is Brushless DC Motor?
Essence of a brushless DC motor with electronic commutation device to replace the machinery of DC motor commutation, ... DC power supply via the controller to the motor stator winding supply, the motor rotor position by the position sensor signal to trigger the controllerthe power switching elements, ...
The brushless DC motor is self-control inverter. It is the general inverter. Its output frequency is not an independent regulator, but by the rotor position detector installed in the synchronous motor axis control. Whenever the rotor turned a certain position (for example 90 ° or 120 ° electrical angle), the position detector will produce a corresponding signal, acting on the corresponding semiconductor components, so that the corresponding phase winding energized to produce torque. The motor rotor turned every one pair of poles, the semiconductor components in turn turns on for a week, AC inverter output corresponding to changes in a cycle. Controlled inverter output frequency and speed of the motor is always in sync, does not appear out of step phenomenon. In small brushless DC motor, the inverter transistors. The transistor has the ability to self-shutdown as long as its base on the control signal disappear, the transistor on its own shutdown, so the control is relatively simple. Larger brushless DC motor, inverter thyristors. Thyristor does not turn-off ability, can not rely on to remove the trigger signal to turn off. Therefore, when a phase current deadline to another phase power, how to turn off the thyristor of the original pilot, the current transfer to the new phase thyristor between the thyristor converter is the key technology of the thyristor motor.
The rotor position detector mounted on the motor shaft is an important component of the brushless DC motor. It determines the armature windings of each phase began to live the moment. It acts as a general DC motor brushes. Change the position of the detector signal time (phase), the equivalent of the DC motor to change the location of the brush in the space, has a great influence on the characteristics of the brushless DC motor. The structural type of the position detector, which typically include a stationary detector elements and a rotating together with the motor rotor position signal shaper. In the location of the detector by the Hall elements, Hall elements is detecting element, the motor rotor magnetic pole position signal shaper. Other structures, such as electromagnetic induction, photoelectric, according to the recent switch-often took advantage of a gap in the disc as a position signal formation. For example, take advantage of this gap in the photoelectric light exposure to the phototube signal is generated to change the opening of the magnetic circuit of the transformer; this gap in the electromagnetic induction using the electromotive force generated in the detection coil.