What Is The Difference Between A Brush-less Motor And A 

Servo Motor Used in An Automatic Ticket Checking Turnstile?

AFC(Automatic Fare Collection) system continuously integrates computer technology, network technology, communication technology, automatic control technology, database technology, mechanical technology, sensing technology and other high and new technologies in its development. Speed turnstile(automatic ticket checking swing turnstile and flap barrier turnstile), also known as automatic ticket checking turnstile, is evolved from the AFC system station terminal equipment, so as to be applied in places which require ticket checking. AFC station terminal equipment mainly includes automatic ticket selling machine, automatic ticket checking machine, automatic check-in machine, etc. Its value accounts for about 60% of the whole AFC system, and its position and role in the AFC system are very important. The upstream industries of AFC terminal equipment manufacturing are stainless steel materials, industrial computer and electronic components, mechanical and electrical equipment and parts, and processing and manufacturing of professional functional modules, etc., while the downstream industries are mainly urban rail transit, high-speed rail, BRT(Bus Rapid Transit), large public venues, tourist attractions and other industries.

An automatic ticket checking turnstile is made up of thousands of spare parts, involved in face recognition system, QR code identification, IC card, ID card, fingerprint recognition, sheet metal manufacturing, housing structure (flap gate and swing gate), assembly, software and hardware system debugging, and so no.

DC servo motor is divided into brushed servo motor and brushless servo motor. Brushed servo motors have the characteristics of low cost, simple structure, large starting torque, wide speed regulation range, and easy control. But the brushed servo motor is not convenient to maintain (to change carbon brush), and it will generate electromagnetic interference, which have environmental requirements. Therefore, the brushed servo motors fit for cost-sensitive general industries and civil applications.  

Why is DC servo motor divided into brushed and brushless motor?

1. Brushless motor is small in size, light in weight, high in force, fast response, high speed, small inertia, smooth rotation and stable torque. The control is complex, easy to realize the intelligence. The electronic commutation of brushless motor is flexible, and can be square wave commutation or sine wave commutation. Brushless servo motor is maintenance-free, high efficiency, low operating temperature, low electromagnetic radiation, long life, and can be used in various environments.

2. AC servo motor is also brushless motor, which can be divided into synchronous motor and asynchronous motor. Currently, synchronous motor is generally used in motion control, and its power range is large, which can achieve great power. The synchronous motor has large inertia, and low maximum rotation speed. With the increase of power, the rotation speed decreases rapidly. Therefore, the synchronous motor is suitable for low speed and smooth operation applications.  

3. The rotor inside the servo motor is a permanent magnet, and the U/V/W three-phase electricity controlled by the driver forms an electromagnetic field. The rotor rotates under the action of this magnetic field. At the same time, the encoder of the motor feeds back the signal to the driver. The driver compares the feedback value with the target value and adjusts the rotation angle of the rotor. The precision of servo motor depends on the precision of encoder (line number). 

The difference between AC servo motor and brushless DC servo motor in function: AC servo is better, because it is sinusoidal wave control, and torque pulsation is small. DC servo motor is trapezoidal wave. But DC servo motor is simpler and cheaper.  

DC servo motor can be used in spark machine, manipulator, precision machine and so on.  At the same time, DC servo motor can be equipped with 2500P/R high degree of analysis of the standard encoder and speed sensor, and also can be equipped with gearbox, so that mechanical equipment can be with reliable accuracy and high torsion. The speed regulation of DC servo motor is good. With unit weight and volume, output power of DC servo motor is the highest, and is greater than AC motor, far more than stepper motor. The torque fluctuation of multistage structure is small.

The difference between a servo motor and a brushless motor is the common brush-commutator configuration. The commutation of a servo DC motor has always been achieved by contacting a graphite brush with an annular commutator mounted on the rotor.  

The brushless motor feeds the rotor position back to the control circuit through Hall sensor so that it can know the exact time of the motor commutation reversal. Most brushless motor manufacturers produce motors with three Hall effect positioning sensors. Brushless motors have no brushes and no related interfaces, so they are cleaner, less noisy, virtually maintenance-free, and have a longer life.  

Under normal conditions, the rotor magnetic pole of a brushless DC motor uses tile type magnetic steel. Through magnetic circuit design, the air gap density of trapezoidal wave can be obtained. The stator windings mostly use concentrated integral pitch windings, so the induced back electromotive force is also trapezoidal wave. The control of brushless DC motor needs position information feedback, so it must have position sensor or use sensorless estimation technology to form automatic speed control system. When controlling the phase current, the inverter output voltage can be controlled according to the brushed DC motor PWM method. In essence, brushless DC motor is also a permanent magnet synchronous motor. The speed regulation actually belongs to the variable voltage and variable frequency speed regulation category.

Generally speaking, AC permanent magnet synchronous servo motor has stator three-phase distributed winding and permanent magnet rotor. In magnetic circuit structure and winding distribution, the induced electromotive force waveform is guaranteed to be sinusoidal, and the added stator voltage and current should also be sinusoidal, generally provided by AC transformer. Permanent magnet synchronous motor control system usually adopts automatic control, and also needs position feedback information, and can use advanced control modes like vector control (magnetic field directional control) or direct torque control.  

The difference between DC brushed motor and DC brushless motor can be considered as square wave and sine wave control resulting in different design concepts. "DC frequency conversion" of brushless DC motor is essentially through the inverter AC frequency conversion. Based on the motor theory, the brushless DC motor and AC permanent magnet synchronous servo motor are similar, so brushless DC motor should be classified as AC permanent magnet synchronous servo motor, but brushless DC motor is used to being classified as DC motor, because from the control and drive power and control object's point of view, it might be appropriate to call it a brushless DC motor. 

What is the difference between servo motor and direct drive motor?

Servo motor means that the motor is driven by the high frequency pulse sent by the servo driver, which can achieve the output of fixed angle, speed and torque. It refers to the type of motor.  

Direct drive motor means that the motor is directly rigidly connected to the load without any transmission mechanism or coupling. It refers to how the motor works.  

Servo motor can be directly connected to the load or can be loaded through the  transmission device. Direct drive motors can be servo motors or other motors.  

The servo motor only converts electrical energy into mechanical energy, but its lower part also needs to be connected to various transmission devices (such as belts, lead screws, rollers, etc.) to achieve your transmission requirements. Direct drive motor does not need other transmission devices, and can be directly connected to equipment. For example, washing machine drum is directly connected to the motor, reducing the connection parts of the mechanical transmission.

In a word, automatic ticket checking turnstile with brushed motor will be wear and tear with the passage of time and long-term use. It needs constant correction and reset to restore the original adjustment state, otherwise the failure rate is high. Automatic ticket checking turnstile with brushed motor can be divide into integrated servo motor and direct drive servo motor, but also depends on the technical adjustment level of all kinds of ticket checking turnstile manufacturers. In terms of technical level, the direct drive servo is better than the integrated servo, and the integrated servo is better than the door mechanism of the ticket checking turnstile with brush motor. In terms of technical level, the direct drive servo motor is better than the integrated servo motor, and the integrated servo motor is better than the automatic ticket checking turnstile with brushed motor. Generally speaking, ticket checking turnstile with servo technology is no wear, and has long service life, which is suitable for industrial public station and rail transportation places such as subway, high-speed rail, customs office, airports, border inspection, intelligent rail, etc.