With the rapid development of power electronics technology, the performance index of frequency conversion speed regulation can fully meet or exceed the DC motor speed control system. By adjusting the pulse frequency of the input driver and the subdivision parameters of the driver to adjust the speed of the stepper motor, it is actually the number of steps of the stepper motor in unit time. First, change the pole logarithmic shift advantage: 1, no additional slip loss, high efficiency; 2, the control circuit is simple, easy to maintain, the price is low; 3, with the stator voltage regulator or electromagnetic slip clutch can be achieved with higher efficiency and smooth speed regulation. Disadvantages: There is step-level speed regulation, which can not achieve stepless smooth speed regulation, and due to the limitation of motor structure and manufacturing process, it can only achieve 2 to 3 kinds of pole-level stepless speed regulation, and the speed regulation range is quite limited. Second, frequency control Advantages: 1. No additional slip loss, high efficiency, wide speed range; 2. For low load operation time, or frequent and stop, it can achieve the purpose of saving electricity and protecting the motor. Disadvantages: The technology is more complicated and the price is higher. Third, the commutator motor speed Advantages: 1. It has simple structure of AC synchronous motor and good speed regulation performance of DC motor; 2. Power supply voltage at low speed, natural commutation with stepping motor back EMF at high speed, reliable operation; 3. No additional slip loss, High efficiency, suitable for starting and speed regulation of high speed and large capacity synchronous motors. Disadvantages: The overload capacity is low, and the capacity of the original motor cannot be fully utilized. Fourth, string speed regulation Advantages: 1. The slip energy generated in the speed regulation process can be used for feedback. High efficiency; 2, the device capacity is proportional to the speed regulation range, suitable for 70% to 95% of the speed regulation. Disadvantages: low power factor, harmonic interference, no braking torque during normal operation, suitable for loads in single quadrant operation. Five, stator voltage regulation Advantages: 1. The circuit is simple, the device is small, and the price is cheap; 2. It is convenient to use and maintain. Disadvantages: 1. Increase the slip loss during the speed regulation process. This loss makes the rotor heat up, and the efficiency is low. 2. The speed regulation range is relatively small. 3. It requires high-slip motor, such as specially designed torque motor, so the characteristics are better. Soft, generally suitable for asynchronous motors up to 55kW. Sixth, electromagnetic clutch speed regulation Advantages: 1. Simple structure, small control device capacity and low value; 2. Reliable operation and easy maintenance; 3. No harmonic interference. Disadvantages: 1. The speed loss is large, because the electromagnetic slip clutch itself has a large difference, so the maximum speed of the output shaft is only 80% to 90% of the synchronous speed of the motor; 2. The slip power is converted into heat energy form during the speed regulation process. Loss, low efficiency. Seven, rotor string resistance speed regulation Advantages: 1. Low technical requirements and easy to master; 2. Low equipment cost; 3. No electromagnetic harmonic interference. Disadvantages: 1, string cast iron resistance can only be stepped speed regulation. If the liquid resistance is used for stepless speed regulation, the maintenance and maintenance requirements are high; 2. The additional slip power in the speed regulation process is converted into the loss of the series resistance heat generation, and the efficiency is low. 3. The speed adjustment range is not large. Hf Drivers - Neodymium,Bullet Tweeter Speaker,Loud And Ultra Crisp Sound,Compression Driver NINGBO BOILINGSOUND ELECTRONICS CO.,LTD , https://www.tweeterspeaker.com