Brushless motor general indicators

Date:2018-03-31 Author: Click:

The brushless DC motor itself is an electromechanical energy conversion part. It has a sensor in addition to the motor armature and the permanent magnet excitation. The motor itself is the core of the brushless DC motor. It not only relates to performance indicators, noise, vibration, reliability and service life, but also involves manufacturing costs and product costs. Due to the use of a permanent magnetic field, the brushless DC motor can get rid of the traditional design and structure of a conventional DC motor, meet the requirements of various application markets, and develop in the direction of simple copper and material saving. The development of permanent magnet magnetic fields is closely related to permanent magnet materials. The application of third generation permanent magnet materials has promoted the development of DC brushless motors to high efficiency, miniaturization, and energy saving.

In order to achieve electronic commutation, there must be a position signal to control the circuit. Early position signals were acquired using electromechanical position sensors, and position signals were now gradually obtained using electronic position sensors or other methods. The easiest way is to use the potential signals of the armature windings as position signals.

To achieve motor speed control must have a speed signal. The speed signal is obtained by obtaining a position signal similar method. The simplest speed sensor is a combination of a frequency measuring tachometer generator and an electronic circuit.

Brushless DC motor commutation circuit consists of two parts drive and control, the two parts are not easy to separate, especially low-power circuits often integrate the two as a single application-specific integrated circuit.

In a power-intensive motor, the drive circuit and the control circuit can be integrated into one. The drive circuit outputs electrical power, drives the armature windings of the motor, and is controlled by the control circuit. At present, the drive circuit has changed from a linearly amplified state to a pulse-width modulated switching state, and the corresponding circuit composition has also been converted from a discrete transistor circuit to a modular integrated circuit.

Modular integrated circuits include power bipolar transistors, power field effect transistors, and isolated gate field effect bipolar transistors.

The control circuit is used to control the motor speed, steering, current (or torque) and protect the motor over-current, over-voltage, overheating and so on. The above parameters are easily converted into analog signals, and the control is relatively simple. However, from the perspective of development, the parameters of the motor should be converted into digital quantities, and the motor can be controlled through a digital control circuit. At present, there are three types of control circuits: an application-specific integrated circuit, a microprocessor, and a digital signal processor. The use of digital signal processors to form the control circuit is the future direction of development.

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