The Steps Of Selecting Types Of Simo Motor? (I)

 

The basic information required for the selection of Xi'an Simo motor includes: the type of load driven, rated power, rated voltage, rated speed, and other conditions.

 

 

1. Type of load driven by the motor

 

This has to be said from the characteristics of the motor. Xi'an Simo motor can be simply divided into DC motors and AC motors, and AC motors are divided into synchronous motors and asynchronous motors.

 

1. DC motor

 

The advantage of DC motors is that they can easily adjust the speed by changing the voltage and can provide a large torque. They are suitable for loads that need to adjust the speed frequently, such as rolling mills in steel mills and hoists in mines. But now with the development of frequency conversion technology, AC motors can also adjust the speed by changing the frequency. However, although the price of frequency conversion motors is not much more expensive than ordinary motors, the price of frequency converters accounts for a large part of the entire set of equipment, so DC motors also have the advantage of being cheap.

 

The disadvantage of DC motors is that they are complex in structure. Any device with a complex structure will inevitably lead to an increased failure rate. Compared with AC motors, DC motors have complex windings (field windings, commutation windings, compensation windings, and armature windings), as well as slip rings, brushes, and commutators.

 

Not only does it require high manufacturing process for Xi'an Simo Motor, but the later maintenance cost is also relatively high. Therefore, DC motors are in an awkward situation in industrial applications, gradually declining but still useful in the transition stage. If the user has sufficient funds, it is recommended to choose an AC motor with a frequency converter. After all, using a frequency converter also brings many benefits, which I will not elaborate on.

 

 

2. Asynchronous motor

 

The advantages of asynchronous motors are simple structure, stable performance, easy maintenance and low price. The manufacturing process is also the simplest. I once heard an old technician in the workshop say that the time it takes to assemble a DC motor is enough to assemble two synchronous motors or four asynchronous motors of similar power. Therefore, asynchronous motors are most widely used in industry.

 

Asynchronous motors are divided into squirrel cage motors and winding motors, the difference lies in the rotor. The rotor of the squirrel cage motor is made of metal bars, copper or aluminum. The price of aluminum is relatively low, and my country is a major aluminum ore country, so it is widely used in occasions with low requirements. However, the mechanical properties and electrical conductivity of copper are better than aluminum, and most of the rotors I have come into contact with are copper. After the squirrel cage motor solves the problem of broken row in the process, the reliability is far greater than that of the motor with winding rotor.

 

The disadvantage is that the torque obtained by the metal rotor cutting the magnetic flux lines in the rotating stator magnetic field is small, and the starting current is large, which makes it difficult to cope with loads requiring large starting torque. Although increasing the length of the motor core can obtain more torque, the strength is very limited.

 

When the wound-rotor motor is started, the rotor winding is energized through the slip ring to form a rotor magnetic field, which moves relative to the rotating stator magnetic field, thus obtaining a greater torque. During the starting process, a water resistor is connected in series to reduce the starting current. The water resistor is controlled by a mature electronic control device to change its resistance value during the starting process.

 

Suitable for rolling mills, hoists and other loads. Since the wound asynchronous motor has more slip rings, water resistors, etc. than the squirrel cage motor, the overall equipment price has increased to a certain extent. Compared with the DC motor, its speed regulation range is narrower and the torque is relatively small, and the corresponding value is also low.

 

 

However, the asynchronous motor creates a rotating magnetic field by energizing the stator winding, and the winding is an inductive element that does not do work, so it absorbs reactive power from the power grid, which has a great impact on the power grid. When a high-power inductive appliance is connected to the power grid, the grid voltage drops and the brightness of the lamps decreases.

 

Therefore, the power supply bureau will impose some restrictions on the use of asynchronous motors, which is also something that many factories must consider. Some large electricity users, such as steel mills and aluminum mills, choose to build their own power plants and form their own independent power grids to reduce restrictions on the use of asynchronous motors. Therefore, if asynchronous motors are to meet the use of high-power loads, they need to be equipped with reactive power compensation devices, while synchronous motors can provide reactive power to the power grid through excitation devices. The greater the power, the more obvious the advantages of synchronous motors, which gave rise to the stage for synchronous motors.