Electric network with the rapid development of power electronic technology, the function of the frequency control of motor speed indicators can completely reach even beyond the dc motor speed regulating system. After conditioning input drive pulse frequency and the segmentation parameters to reach regulate the effect of the stepping motor speed, in fact is the control unit of time steps of step motor. One, change log speed interests: (1) no additional slip loss, high power; (2) control circuit short, easy to repair, the price is low; (3) in collaboration with the stator voltage regulator or electromagnetic slip clutch power can be obtained higher smooth speed regulation. Disadvantages: step speed regulation, can't accomplish stepless smooth speed regulation, and because of the limitation of motor structure and manufacturing process normally only completed 2 ~ 3 kinds of logarithm step speed, speed regulation planning co. , LTD. Second, the frequency control of motor speed interests: (1) no additional slip loss, high power, wide speed planning; (2) on low load operation time is longer, or, more frequent occasions stopped, can reach intention of power saving and protection of motor. Weakness: the technology is messy, the price is higher. Three, commutator motor interests: (1) has excellent ac synchronous motor structure brief and dc motor speed control function; (2) low speed with the supply voltage, high speed in step motor against potential natural converter, reliable operation; (3) no additional slip loss, high power, suitable for high speed large capacity synchronous motor starting and speed regulation. Disadvantages: low overload ability, the capacity of original machine cannot give full play to. Four, cascade speed regulation benefits: (1) speed can be happened in the process of slip energy feedback to use them. High power; (2) the equipment capacity is proportional to the speed control planning, apply to 70% ~ 95% of the speed control. Disadvantages: low power factor, harmonic disturbing, normal operation without the brake torque, suitable for single quadrant operation load. Five, the stator voltage regulating speed interests: (1) line brief, equipment is small in size, price cheap; (2) use, convenient repair. Disadvantages: (1) speed control in the process of adding slip loss, the loss of the rotor heat, low power; (2) control plan is small; Adopting high slip motor (3) requirements, such as the special planning of the torque motor, so soft, generally applicable to 55 kw asynchronous motor. Six, electromagnetic slip clutch speed regulation interests: (1) brief structure, control equipment capacity is small, cheap value; (2) the operation is reliable, simple repair; (3) no harmonic disturbance. Lost a big drawbacks: (1) speed, due to large electromagnetic slip clutch slip itself, so the highest speed of the output is only 80% ~ 90% for motor synchronous speed; (2) the speed regulation process transfer the loss of the method of all power is converted into heat energy, the power is low. Seven, rotor resistance speed interests: (1) technical requirements is low, easy to grasp; (2) low cost of equipment; (3) no electromagnetic harmonic disturbance. Disadvantages: (1) resistance will only have used cast iron. If using liquid resistance for stepless speed regulation, the preventive maintenance, the demand is higher; (2) speed control in the process of additional slip power into the list of all the loss of resistance heating method, the power is low. (3) control plan is not big.
