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Correlation between AC motor, rc brushless DC motor

Source:X-TEAMC   Browse:   Release time:2019-10-08 17:12

First of all, the classification of general motors:

1、Divided by working power type:

Can be divided into DC motor and AC motor.

1)DC motors can be divided according to structure and working principle: brushless DC motor and brushed DC motor.


Brushed DC motors can be divided into: permanent magnet DC motors and electromagnetic DC motors.

Electromagnetic DC motor division: series-excited DC motor, shunt DC motor, separately excited DC motor and compound excitation DC motor.

Permanent magnet DC motor division: rare earth permanent magnet DC motor, ferrite permanent magnet DC motor and AlNiCo permanent magnet DC motor.

2)Among them, AC motors can also be divided into: single-phase motors and three-phase motors.


2、According to the structure and working principle, it can be divided into: DC motor, asynchronous motor and synchronous motor.

1)Synchronous motors can be divided into: permanent magnet synchronous motors, reluctance synchronous motors and hysteresis synchronous motors.

2)Asynchronous motors can be divided into: induction motors and AC commutator motors.

Induction motors can be divided into three-phase asynchronous motors, single-phase asynchronous motors and shaded-pole asynchronous motors.

The AC commutator motor can be divided into: single-phase series-excited motor, AC-DC motor and repulsive motor.


3、According to the starting and running modes, it can be divided into: a capacitor-starting single-phase asynchronous motor, a capacitor-operated single-phase asynchronous motor, a capacitor-starting single-phase asynchronous motor, and a split-phase single-phase asynchronous motor.


4、It can be divided according to the purpose: drive motor and control motor.

1)Drive motor can be divided: electric tools (including drilling, polishing, polishing, slotting, cutting, reaming, etc.) with electric motors, household appliances (including washing machines, electric fans, refrigerators, air conditioners, tape recorders, video recorders, DVDs) Motors, vacuum cleaners, cameras, hair dryers, electric shavers, etc.) Motors for motors and other general purpose small mechanical equipment (including various small machine tools, small machines, medical equipment, electronic equipment, etc.).

2)The control motor is further divided into a stepping motor and a servo motor.


5、According to the structure of the rotor, it can be divided into: cage type induction motor (the old standard is called squirrel cage type asynchronous motor) and wound rotor induction motor (the old standard is called winding type asynchronous motor).


Today is mainly to talk about what is usually said to be a brushless motor?

In a narrow sense: a brushless motor is a motor without a brush and a commutator (or collector ring), also known as a commutatorless motor.

Broadly speaking: all brushless motors are brushless motors.


As early as the birth of the motor in the 19th century, the practical motor produced was the brushless form, that is, the AC squirrel-cage asynchronous motor, which has been widely used. However, asynchronous motors have many insurmountable drawbacks, resulting in slow development of motor technology. Transistors were born in the middle of the last century, and DC brushless motors using transistor commutating circuits instead of brushes and commutators have emerged. This new type of brushless motor is called an electronically commutated DC motor, which overcomes the drawbacks of a generation of brushless motors.

Brushless DC motor:

(Read a lot of articles and classified reports, brushless DC motors and brushless DC motor in Baidu entry is pointing in the same entry, including in many articles in brushless DC motors and brushless DC motor is also very confused Severe, almost the same existence. Therefore, in a broad sense, DC brushless motor, brushless DC motor, referred to as BLDCM. But in a narrow sense, DC brushless motor or brushless DC motor single finger An electronically commutated low-power DC motor, also known as a commutatorless motor and a commutatorless DC motor. It is equivalent in structure to a reverse mounted DC motor whose armature is placed on the stator and the rotor is permanent. A magnet whose armature winding is a multi-phase winding, generally three-phase, which can be connected in a star or a triangle. The phase windings are respectively connected to the transistor switches in the electronic commutator circuit.

Abbreviation (BLDCM) - one of the synchronous motors.

(BLDCM) is developed on the basis of brushed DC motor, but its driving current is uncompromising AC; brushless DC motor can be divided into brushless speed motor and brushless torque motor. Generally, brushless motors (in principle, DC brushless motors and AC brushless motors) have two kinds of driving currents, one is a trapezoidal wave (generally "square wave"), and the other is a sine wave. Sometimes the former is called DC brushless motor (in principle, the voltage of the trapezoidal wave is also an AC voltage, but the square wave is more like "DC", so it is called DC brushless motor.), the latter is called AC servo. The motor (specifically, one of the AC servo motors.)

In order to reduce the moment of inertia, brushless DC motors usually adopt a "slender" structure. Brushless DC motors are much smaller in weight and volume than brushed DC motors, and the corresponding moment of inertia can be reduced by 40% to 50%. Due to the processing of permanent magnet materials, the general capacity of brushless DC motors is below 100 kW.

The motor has good linearity of mechanical characteristics and adjustment characteristics, wide speed regulation range, long service life, easy maintenance and low noise, and there is no series of problems caused by brushes. Therefore, such motors have great problems in the control system. Application potential.

The stator windings of the motor are mostly made into a three-phase symmetrical star connection method, which is very similar to the three-phase asynchronous motor (which can be viewed and connected, also called induction motor). A magnetized permanent magnet is adhered to the rotor of the motor, and a position sensor is mounted in the motor for detecting the polarity of the rotor of the motor. The driver is composed of power electronics and integrated circuits, and its functions are: receiving start, stop, and brake signals of the motor to control start, stop, and brake of the motor; accepting position sensor signals and forward and reverse signals for controlling the inverse The power bridges of the transformers are turned on and off to generate continuous torque; the speed command and the speed feedback signal are accepted, which are used to control and adjust the speed; provide protection and display, and etc.

Since the brushless DC motor is operated in a self-controlled manner, it will not be like a synchronous motor with heavy-duty starting under variable frequency speed regulation. (Note: The rotor of the synchronous motor adopts DC excitation and cannot start by itself. Most of them use synchronous start and asynchronous start. The synchronous start is caused by another auxiliary motor to drag the synchronous motor to the synchronous speed, and the power is connected to the power supply at the same time, and the synchronous magnetic field is pulled into the synchronization. The starting method is too complicated, and is rarely used in practice. The asynchronous start is The rotor winding of the motor is short-circuited by a resistor. When the speed is close to the synchronous speed, the resistor is removed and the excitation power is added at the same time, and then the magnetic field of the stator and rotor is pulled into synchronization. The starting method is because the number of turns of the field winding is large, and the field winding is cut during heavy load starting. The rotating magnetic field generates a high voltage, which easily breaks through the windings and causes personal electric shock.) That way, the start winding is added to the rotor, and the oscillation and the out-of-step are not generated when the load is abrupt.

Brushless DC motor has the characteristics of DC brush motor and frequency change device, so it is also known as DC frequency conversion. The international common term is BLDC. The operating efficiency of brushless DC motor, low speed torque, speed accuracy, etc. are better than any. The inverter of control technology is better, so it deserves the attention of the industry. This product has been produced over 55kW and can be designed to 400kW, which can solve the needs of industrial power saving and high performance driving.

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