One time learning about motors - understanding motors, using motors, surpassing motors

One time learning about motors - understanding motors, using motors, surpassing motors
1、 Get to know motors

An electric motor, also known as a motor, is a device that converts electrical energy into mechanical energy. Its main function is to generate driving torque and serve as a power source for electrical appliances or various equipment. Electric motors are ubiquitous in household appliances, industrial equipment, agricultural equipment, military equipment, and transportation vehicles.

There are many types of motors, and when the same motor is classified in different ways, its name may vary slightly. It can be distinguished by working power supply, structure and working principle, starting and running mode, or rotor structure. It can also be classified by purpose, usage scenario, and even speed.

This article has been comprehensively organized based on the type of motor, as follows:

DC brushless motor, also known as DC variable frequency motor (BLDC), adopts Hall sensor electronic commutation, and the coil (armature) does not move magnetically. It can be divided into outer rotor brushless motor and inner rotor brushless motor. Its structure is the same as permanent magnet synchronous motor, and brushless DC motor adopts DC input, but uses synchronous motor frequency conversion technology.

The performance of its use is determined by the brushless electronic speed controller. The driving current of the brushless motor is divided into two types: square wave and sine wave, which are respectively DC brushless motor and AC servo motor, which are one type of AC servo motor.

Brushless motors have advantages such as high efficiency, low energy consumption, low noise, long lifespan, high reliability, servo control, and stepless variable frequency speed regulation. They are smaller in size than brushed DC motors, simpler to control than asynchronous AC motors, have high starting torque and strong overload capacity, but are expensive and difficult to maintain.

Three phase AC motors are divided into synchronous motors and asynchronous motors. Synchronous motors are mostly used for generators, while asynchronous motors are mostly used for electric motors. Asynchronous motor mechanism is simple, easy to maintain, reliable in operation, and inexpensive, and has been widely used. The rotor structure of synchronous motors is more complex and expensive than asynchronous motors. They are not as widely used in production and daily life as asynchronous motors, and are mainly used as generators. Nowadays, synchronous motors are used in thermal power plants, hydropower stations, steam turbines, and water turbines.

A stepper motor is an open-loop control motor that converts electrical pulse signals into angular displacement. It is an induction motor that uses a stepper drive to supply multi-phase timing control current when converting direct current into components.

The optimal working range for stepper motors is 150-500r/min. Stepper motors are often used in synchronous belt drives, flat belt conveyors, and other applications where positioning accuracy is not very high. The closed-loop stepper motor has an encoder added to the tail, which can achieve closed-loop control with a speed of up to 1500r/min. In situations where low-cost and high-precision positioning are required, it can replace general servo systems.

The servo motor controls the speed and position accuracy very accurately, and can convert voltage signals into torque and speed to drive the controlled object. The servo motor places the control circuit outside the motor, and the motor part inside is a standard DC motor or AC induction motor.

The servo motor relies on pulse positioning to receive one pulse, which rotates by one pulse corresponding to an angle, and the encoder sends out a corresponding number of feedback pulses. The feedback pulses and the servo driver receive the pulses to form a closed-loop control, allowing the servo driver to accurately control the motor rotation and achieve precise positioning. The commonly used servo motor is permanent magnet synchronous AC servo.

Generally, industrial servo motors adopt current loop, speed loop, and position loop control modes, which respectively provide feedback on the angular acceleration, angular velocity, and rotational position of the motor during operation. The chip controls the driving current of each phase of the motor through feedback from three sources, achieving accurate operation of motor speed and position.