What is the difference between DC motor and AC motor?

Some friends do not know whether to choose DC motor or AC motor when designing mechanical equipment. In this case, it is necessary to compare DC motor with AC motor. By comparing the two, it is possible to decide which one to use. This method is actually very practical.

1) The unit capacity of DC motor is generally 12-14MW, and it is often made into a double armature form; while the unit capacity of AC motor can be several times that.

2) Due to the limitation of the commutator, the armature voltage of DC motor can only reach more than one thousand volts, while AC motor can reach 6-10kV.

3) DC motor is constrained by the mechanical strength of the commutator part, and its rated speed decreases with the rated power of the motor, generally only hundreds of revolutions per minute to more than one thousand revolutions per minute, while AC motor reaches thousands of revolutions per minute.

4) The volume and weight of DC motor are larger than those of AC motor of the same capacity, and the price is also high.

Finally, it should be pointed out that the AC motor speed control system has great advantages in energy saving. On the one hand, AC load accounts for half or more of the total power consumption. Energy saving of this type of load can achieve considerable power saving benefits. On the other hand, AC drive itself has power saving potential that can be tapped.

In the AC motor speed control system, a certain margin is often left when selecting the motor, and the motor does not always run under the maximum load; if the variable frequency speed control technology is used, the motor speed can be controlled when the load is light, and the purpose of power saving can be achieved. The fans, water pumps, compressors, etc. used in large quantities in industry account for about 50% of the industrial power consumption. If the variable frequency speed control technology is used, its efficiency can be greatly improved and the power consumption can be reduced by 10%.

There are many explanations about DC motors and AC motors, and different people have different views. The specific choice depends on the environment of the equipment and what kind of needs need to be met in the actual operation process to select the appropriate parameters to meet the requirements for use.