Although DC motors are more complex in structure and more inconvenient to maintain than three-phase AC asynchronous motors, they offer better speed regulation performance and...
It has a relatively large starting torque, therefore, it is often used in production machinery with high speed regulation requirements or production machinery that requires a large starting torque.
Driven by a DC motor.
Advantages of DC motors:
(1) It has good speed regulation performance, a wide speed regulation range, and is easy to adjust smoothly.
(2) It has large starting and braking torque, making it easy to start and stop quickly.
(3) Easy to control.
application:
(1) Large-scale equipment with a wide speed range, such as rolling mills, electric locomotives, medium and large gantry planers, mine shaft hoists, and lifting equipment.
equipment.
(2) Places where storage batteries are used as power sources, such as cars and tractors.
Compared to asynchronous motors, shunt (separately excited) motors, although more complex in structure, more expensive, and less convenient to maintain, offer better speed regulation.
It has its unique advantages.
Main advantages:
1. The speed regulation is uniform and smooth, and stepless speed regulation is possible (Note: The method of speed regulation by changing the number of pole pairs in an asynchronous motor is called stepped speed regulation).
2. Wide speed range, with a speed ratio exceeding 200 (the speed ratio equals the ratio of the maximum speed to the minimum speed), therefore mechanical transmissions...
The gearbox used can be greatly simplified.
It can be seen that there are three methods for speed control of DC motors.
Characteristics of reduced speed regulation:
(1) The speed regulation is smooth and stepless speed regulation can be obtained; however, it can only be adjusted upwards, and due to the limitations of the mechanical strength itself, n cannot be too high.
(2) The speed regulation device is simple, economical, has low current, and is easy to control.
(3) It has relatively hard mechanical properties and good stability.
(4) For specially manufactured magnetic motors, the speed adjustment range can reach 3~4, for example 530~2120r/min and 310~1240r/min.
When using magnetic field adjustment for speed control, the following should be noted:
(1) If Ia remains unchanged after speed adjustment, the load torque of the motor must be reduced when it is running at high speed.
(2) This speed regulation method is only applicable to constant power speed regulation (such as for cutting machine tools).
