Brushless DC motor is composed of motor body and driver. The stator winding of motor is mostly made of three-phase symmetrical star connection. The driver is composed of power electronic devices and integrated circuits. The components of the basic structure of DC brush motor include stator, rotor, brush and commutator. The interaction of stator and rotor magnetic fields drives the motor to rotate.
电动机可根据其使用的电源类型分为两大类：AC 电动机和 DC 电动机。顾名思义，交流电动机通常使用交流电源（单相或三相）供电，并且主要用于需要大量扭矩的工业和重型应用中。另一方面，直流电动机（今天我们要关注的焦点）通常较小，并且用于基于电池（或插入直流电源）的应用中，与交流电动机相比，其工作量要少得多。他们发现它在数种设备中都有应用，从剃刀，剃须刀到儿童玩具，机器人和无人机等日常设备，无一例外。
Motors can be divided into two categories according to the type of power supply they use: AC motors and DC motors. As the name suggests, AC motors usually use AC power (single-phase or three-phase) for power supply, and are mainly used in industrial and heavy-duty applications requiring large amounts of torque. On the other hand, DC motors (the focus of our attention today) are usually smaller and are used in battery based (or plug-in DC power) applications with much less work than AC motors. They found that it was used in a number of devices, from razors and razors to children’s toys, robots and drones, without exception.
In DC motor, can be divided into brush DC motor and brushless DC motor, reducer is also like some, in some large torque goods, must use DC reducer, so what is the difference between brush DC motor and brushless DC motor?
The DC speed reduction of brush motor is a typical mechatronics commodity. It is composed of DC motor and controller. The operation method is automatic control. It is not easy to be like the synchronous motor with DC variable speed and light load starting, so it is not easy to cause fluctuation and out of step when the load changes suddenly. In terms of structure, both brushless DC motor and brushless DC motor have motor rotor and motor stator, but the structure of these two kinds of DC reducer is the reverse. The motor rotor of Brushless DC reducer is electromagnetic coil, which is connected with the output shaft, and the motor stator is permanent magnet material. The DC reducer of brush motor is different. Its motor rotor is made of permanent magnet material and connected with the output shaft together with the housing. The winding electromagnetic coil is the motor stator, and there is no motor and motor rotor to complete the commutation of electronic devices according to Hall element.
The DC reducer of brush motor alternates the frequency and wave pattern by changing the current wave input to the stator electromagnetic coil of the motor. Around the winding electromagnetic coil, an electromagnetic field is generated to rotate around the geometric pivot of the DC reducer. The electromagnetic field drives the permanent magnet material on the motor rotor to rotate, and the DC motor just starts to rotate. The characteristics and characteristics of the DC reducer are similar The total number of permanent magnet materials, the compressive strength of magnetic flux and the size of input working voltage are related to the operating characteristics. The speed change of brush motor DC reducer must be controlled by single chip microcomputer design and power supply circuit. Its price and cost are much higher than that of brush motor DC reducer.
But this kind of DC reducer also has many advantages
1. Without carbon brush, there will be no friction flame, which greatly reduces the impact of spark discharge on wireless communication equipment;
2. When the DC reducer is running, the noise will be lower because of the reduction of friction;
3. The service life is basically tens of thousands of enterprises, but it is related to the quality of rolling bearing. The service life of brush DC reducer is generally hundreds or thousands of hours, and the carbon brush must be removed and replaced when it reaches the application limit;
4. The control method of the brush motor DC reducer is the data DC frequency conversion control, which has strong controllability. It can be completed from several minutes to more than 100000 revolutions. The speed ratio of the brush motor DC reducer is stable after starting, and the speed change is simple;
5. The DC reducer with brush motor is generally used to operate the commodities with high speed ratio and long-term operation, such as high-precision instruments, intelligent robots, etc.
First, the working principle is different
Working principle of Brushless DC motor: the rotor of the motor is bonded with magnetized permanent magnet to detect the polarity of the motor rotor, and the driver controls the start, stop and braking of the motor; controls the on-off of each power tube of the inverter bridge to generate continuous torque; controls and adjusts the speed and provides protection and display, etc.
Working principle of DC brush motor: when the motor rotates, the carbon brush slides on the commutator to generate a rotating magnetic field which is attracted by the static magnetic field of the stator. The current in the armature and stator winding is supplied by the battery or other DC power supply to provide constant DC voltage to the battery (or DC power supply).
Second, the structure is different
Brushless DC motor is composed of motor body and driver. The stator winding of motor is mostly made of three-phase symmetrical star connection. The driver is composed of power electronic devices and integrated circuits.
The components of the basic structure of DC brush motor include stator, rotor, brush and commutator. The interaction of stator and rotor magnetic fields drives the motor to rotate.
Working principle and structure
In general, two of all electric motors are based on the principle of Ampere’s law and Faraday’s law. The first law states that if the component of any current flowing through a conductor is at right angles to the electric field, the electric conductor placed in a magnetic field will be subjected to a force. The second principle states that if a conductor moves in a magnetic field, any motion component perpendicular to the magnetic field will produce a potential difference between the two ends of the conductor.
Based on these laws, the motor consists of two main parts. A permanent magnet and a stack of conductors are wound into a coil. By applying electricity to the coil, it becomes a magnet and rotates based on the fact that the magnet repels at the same pole and attracts at different poles.
Advantages and disadvantages
In a brush DC motor, the brush is always in contact with the rotary commutator. This leads to a lot of friction, which leads to heat loss, energy loss and brush wear. Therefore, the efficiency of the brushless DC motor is low and needs regular maintenance. This creates a lot of friction, and friction equals heat (energy loss) and wear. On the other hand, brushless DC motor is friction free in nature, so it has high efficiency, needs zero maintenance, and has longer service life than brushless DC motor.
However, the brushless DC motor is a brushless DC motor. Because of its simple design, it is cheaper than the similar products. On the other hand, brushless DC motors are very expensive due to their complex design and the extra cost of the additional electronic components (controllers) required to drive them.
无刷直流电动机的设计复杂性使其与有刷直流电动机相比非常昂贵。在购买无刷直流电动机之前，请确保该项目的额外费用在可承受的范围内。在做出决定之前，还要考虑使用 BLDC 所需的其他附件的成本。
The design complexity of BLDCM makes it very expensive compared with BLDCM. Before purchasing a brushless DC motor, please make sure that the additional cost of the project is affordable. Before making a decision, consider the cost of other accessories needed to use the BLDC.