The ordinary motors, stepper motors, servo motors, and servos referred to here refer to DC micro motors 

and we often come into contact with DC motors. Electric motor, also known as "motor", refers to an electromagnetic induction device that maintains the transformation or transmission of electromagnetic energy according to the law of electromagnetic induction. Motor, also known as (alias motor), is expressed in the power circuit using the English letter "M" (formerly known as "D"). Its main function is to generate driving torque, which is used as a power source for electrical appliances or various machines. The generator is represented by the letter "G" in the circuit.

Ordinary motor

Ordinary motors are commonly seen in electric toys, razors, etc. They are usually DC brushed motors. 

This type of motor has the characteristics of high speed and low torque. Generally, it only has two pins. 

When the positive and negative poles of the battery are connected to the two pins, it will start rotating. 

Then, when the positive and negative poles of the battery are connected to the two pins in opposite 

directions, the motor will rotate in the opposite direction.

Gear motor

A deceleration motor is a combination of an ordinary motor and a gearbox, which reduces the speed and 

increases the torque, making the ordinary motor more widely applicable.

Stepper motor

A stepper motor is an open-loop control element that converts electrical pulse signals into angular 

displacement or linear displacement. In non overloaded situations, the speed and stopping position of 

the motor depend only on the frequency and number of pulses of the pulse signal, and are not affected 

by load changes. When the stepper driver receives a pulse signal, it drives the stepper motor to rotate a 

fixed angle in the set direction, called the "step angle", and its rotation runs step by step at a fixed angle. 

By controlling the number of pulses, the angular displacement can be controlled to achieve accurate 

positioning; At the same time, the speed and acceleration of the motor can be controlled by controlling 

the pulse frequency, thus achieving the purpose of speed regulation.

steering engine

The servo motor is mainly composed of a casing, a circuit board, a coreless motor, gears, and a position 

detector. Its working principle is that the receiver sends a signal to the servo, which is then determined by 

the IC on the circuit board to determine the direction of rotation. The coreless motor is then driven to start 

rotating, and the power is transmitted to the swing arm through the reduction gear. At the same time, the 

position detector sends back a signal to determine whether the positioning has been reached. The position 

detector is actually a variable resistor, and the resistance value changes when the servo rotates. By detecting 

the resistance value, the angle of rotation can be determined.

The specifications provided by servo motor manufacturers usually include basic information such as external 

dimensions (mm), torque (kg/cm), speed (seconds/60 °), test voltage (V), and weight (g). The unit of torque 

is kg/cm, which means that at a length of 1 cm on the swing arm, it can lift several kilograms of weight. 

This is the concept of a lever arm, therefore the longer the length of the swing arm, the smaller the torque. 

The unit of speed is sec/60 °, which means the time required for the servo to rotate 60 °.

servo motor 

Servo motor, also known as actuator motor, is used as an actuator in automatic control systems to convert 

received electrical signals into angular displacement or angular velocity output on the motor shaft. It is 

divided into two categories: DC and AC servo motors. Its main feature is that when the signal voltage is zero, 

there is no self rotation phenomenon, and the speed decreases uniformly with the increase of torque.

Servo motors mainly rely on pulses for positioning. Basically, it can be understood as follows: when a servo 

motor receives one pulse, it will rotate the corresponding angle of one pulse to achieve displacement. 

Because servo motors themselves have the function of emitting pulses, every time they rotate an angle, they 

will emit a corresponding number of pulses. This forms a response or closed loop with the pulses received 

by the servo motor. In this way, the system will know how many pulses have been sent to the servo motor 

and how many pulses have been received back. In this way, the rotation of the motor can be accurately 

controlled to achieve precise positioning, which can reach 0.001mm.

Servo motors are divided into two categories: AC servo and DC servo.

AC servo motors are divided into two types: asynchronous AC servo motors and synchronous AC servo 

motors.

DC servo motors are divided into brushed and brushless motors. Brushed motors have low cost, simple 

structure, large starting torque, wide speed range, easy control, and require maintenance. However, 

maintenance is inconvenient (such as replacing carbon brushes) and generates electromagnetic interference,

which has environmental requirements. Therefore, it can be used in cost sensitive general industrial and 

civilian applications.

Principle of Reduction Motor

Gear reduction motor, also known as gear reduction motor or reduction motor, is a closed transmission gear 

reduction device driven by a motor. It is a reduction transmission mechanism that integrates the motor and 

gearbox to reduce speed and increase torque, in order to meet the needs of mechanical equipment operation.

The purpose of a reduction gear motor is to reduce the speed.

The required speed of the motor is achieved through a reduction gearbox, commonly known as the output 

speed Increase torque.

Under the same power conditions, the slower the output speed of the gear reduction motor, the greater the 

torque, and vice versa Change the transmission direction.

For example, we can use two sector gears to vertically transmit force to another axis of rotation Clutch 

function.

We can achieve the goal of instant braking when power is cut off by installing a brake clutch.

Basic principle of stepper motor

working principle:

Usually, the rotor of a motor is a permanent magnet, and when current flows through the stator winding, a 

vector magnetic field is generated by the stator winding. The magnetic field will drive the rotor to rotate by 

an angle, so that the direction of the rotor's pair of magnetic fields is consistent with that of the stator's 

magnetic field. When the vector magnetic field of the stator rotates by an angle. The rotor also rotates an 

angle with the magnetic field. For every input of an electrical pulse, the motor rotates one angle and 

advances one step. The angular displacement output is proportional to the number of pulses input, and the 

rotational speed is proportional to the pulse frequency. Changing the order of winding electrification will 

cause the motor to reverse. So the rotation of the stepper motor can be controlled by controlling the number 

and frequency of pulses, as well as the sequence of energizing each phase winding of the motor.

Heating principle:

Various types of motors commonly seen have iron cores and winding coils inside. The winding has resistance, 

and when energized, it will produce losses. The magnitude of the losses is proportional to the square of the 

resistance and current, which is commonly known as copper losses. If the current is not a standard DC or 

sine wave, harmonic losses will also occur; The iron core has hysteresis eddy current effect, which can also 

cause losses in alternating magnetic fields. The magnitude of these losses is related to the material, current, 

frequency, and voltage, which is called iron loss. Copper and iron losses will both manifest in the form of 

heat, thereby affecting the efficiency of the motor. Stepper motors generally pursue positioning accuracy 

and torque output, with relatively low efficiency, large current, and high harmonic components. The frequency

 of current alternation also varies with the speed, so stepper motors generally have heating problems, which 

are more severe than general AC motors.

Principle of servo motor

The PWM wave enters the internal circuit to generate a bias voltage, triggering the motor to move the 

potentiometer through the reduction gear. When the voltage difference is zero, the motor stops rotating, 

thus achieving the servo effect.

The PWM protocol for servos is the same, but the latest servos may be different

The protocol is generally: the high-level width is between 0.5ms and 2.5ms to control the servo to rotate at 

different angles.

Working principle of servo motor

The working principle of servo motors is relatively simple, but their operation is relatively efficient. The servo 

circuit is built into the motor unit and uses a flexible shaft typically equipped with gears. The electrical signal 

controls the motor and also determines the amount of shaft movement. The internal setup of the servo 

motor is simple: a small DC motor, control circuit, and potentiometer. The DC motor is connected to the 

control wheel through gears. When the motor rotates, the resistance of the potentiometer changes, and the 

control circuit can accurately adjust the motion and direction.

When the shaft is in the correct (ideal) position, the motor stops supplying power. If the shaft does not stop 

at the target position, the motor continues to run until it enters the correct direction. The location of the 

target is transmitted through a signal line using electrical pulses. So, the speed of the motor is directly 

proportional to the actual and ideal positions. When the motor approaches the desired position, it begins 

to slowly rotate, but when the motor rotates farthest, the speed is very fast. In other words, servo motors 

only need to complete tasks as quickly as possible, making them highly efficient devices.