Technical Knowledge

Introduction of brushless motor, brush motor, servo motor, stepper motor, reduce
Release Date : 2020-08-19 18:22:06

The motor converts the supplied electrical energy into mechanical energy, and various types of motors are generally used. Generally, when mechanical engineers design electrical equipment to perform mechanical tasks, they first consider how to convert electrical energy into kinetic energy. Therefore, drives and motors occupy important components in mechanical equipment.
Motors vary according to their power type (AC or DC) and the method of rotation. Below, we briefly introduce the functions and uses of each type.



1. Brushed motor

The simplest type of motor is a brushed DC motor. In this type of motor, current flows through coils arranged in a fixed magnetic field. The current creates a magnetic field in the coil. This causes the coil assembly to rotate because each coil is pushed away from the same pole of the fixed pole and pulled toward the other pole of the fixed pole. In order to keep rotating, the current must be constantly reversed so that the polarity of the coil is constantly reversed, so that the coil continues to "catch up" with a polarity different from the fixed pole. The coil is powered by a fixed conductive brush in contact with the rotating commutator. The rotation of the commutator causes the current flowing through the coil to reverse. Commutators and brushes are the key components that distinguish brushed DC motors from other motor types.


The fixed brushes supply electric energy to the rotating commutator. When the commutator rotates, it will continuously flip the direction of the current into the coil, thereby reversing the polarity of the coil, so that the coil keeps rotating to the right. The commutator rotates because it is connected to the rotor with the coil installed.

2. Brushless motor

The brushless motor has no brushes as its name implies. The brushless DC motor consists of the motor body and the driver, and is a typical mechatronic product. Since the brushless DC motor runs in a self-controlled manner, it will not add a start winding to the rotor like a synchronous motor that is started under heavy load under variable frequency speed regulation, nor will it cause oscillation and loss of step when the load changes suddenly. The permanent magnets of medium and small capacity brushless DC motors are now mostly made of rare earth neodymium iron boron (Nd-Fe-B) materials with high magnetic energy levels. Therefore, the volume of the rare earth permanent magnet brushless motor is reduced by one frame size than the three-phase asynchronous motor of the same capacity.


Since the rotor is a permanent magnet, there is no need for current, so there is no need for brushes and commutators. The current flowing to the fixed coil is controlled from the outside.
The common ones in life are electric vehicle motors. Old-fashioned motors have brushes to change the direction of the current. The torque is large when starting the fast start, which is easy to break and easier to repair. The newer types are all brushless motors, which rely on electronic equipment to change the direction of current, start up stably, have a small torque, and are difficult to repair when broken. The above two motor controllers are very simple and cannot adjust voltage or position, that is, they cannot control the rotation angle of the motor. The motor can adjust the voltage and position, and requires a dedicated controller to control and power. For example, through programming, the speed of the motor can be compromised at 720 degrees per second, and the tangent is 36 degrees and 30 minutes. Of course, the accuracy of the motor cannot be different. The motor rotates fast and the torque increases.

?3. Stepper motor

Stepping motor is an open-loop control motor that converts electrical pulse signals into angular displacement or linear displacement. It is the main executive element in modern digital program control systems and is widely used. In the case of non-overload, the motor speed and stop position depend only on the frequency and pulse number of the pulse signal, and are not affected by the load change. When the stepper driver receives a pulse signal, it drives the stepper motor The set direction rotates at a fixed angle, called "step angle", and its rotation runs step by step at a fixed angle. The angular displacement can be controlled by controlling the number of pulses, so as to achieve the purpose of accurate positioning; at the same time, the speed and acceleration of the motor rotation can be controlled by controlling the pulse frequency, so as to achieve the purpose of speed regulation.
Stepper motor is a kind of induction motor. Its working principle is to use electronic circuit to transform direct current into time-sharing power supply, multi-phase sequential control current, use this kind of current to power the stepper motor, the stepper motor can work normally. The driver is a time-sharing power supply for the stepper motor, a multi-phase sequential controller.
The stepper motor can accurately control the rotation angle, but the brushless motor cannot. The stepper motor rotor is a grass-grazing structure, with neither windings nor permanent magnets; while the brushless motor rotor is a rotating rectifier plus an excitation winding. Brushless motors are generally used For power generation and high-power dragging; stepper motors are generally used in occasions that require precise positioning, such as tool displacement control on machine tools.
Although the stepper motor has been widely used, the stepper motor is not like an ordinary DC motor, and the AC motor is used conventionally. It must be composed of a dual ring pulse signal, power drive circuit, etc. to form a control system before it can be used. Therefore, it is not easy to use a stepper motor well. It involves many professional knowledge such as machinery, electrical machinery, electronics and computers. As an executive element, stepping motor is one of the key products of mechatronics and is widely used in various automation control systems. With the development of microelectronics and computer technology, the demand for stepper motors is increasing day by day, and they are applied in various fields of national economy.

?4. Servo motor

Servo motor refers to the engine that controls the operation of mechanical components in the servo system, and is an auxiliary motor indirect speed change device.
The servo motor can control the speed and position accuracy very accurately, and can convert the voltage signal into torque and speed to drive the control object. The rotor speed of the servo motor is controlled by the input signal and can react quickly. It is used as an actuator in an automatic control system and has the characteristics of small electromechanical time constant, high linearity, and starting voltage. Converted into angular displacement or angular velocity output on the motor shaft. Divided into two major categories of DC and AC servo motors, its main feature is that there is no rotation when the signal voltage is zero, and the speed decreases at a uniform speed as the torque increases.

?5. Geared motor

Geared motor refers to the integrated body of reducer and motor (motor). Such an integrated body can also be commonly referred to as a gear motor or a gear motor. Usually, a professional reducer manufacturer will integrate and assemble it and supply it as a whole with the motor.

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