Research On An Adaptive Power-saving Controller For Asynchronous Motors

Three-phase asynchronous motor is a kind of electric drive device which can translate electrical energy into mechanical energy. It is mainly made up of the stator, rotor and the air gap between them. When the stator windings are connected to the three-phase power, the stator windings will form rotating magnetic field and cut rotor to obtain the torque. Three-phase AC induction motors with advantages of simple structure, reliability and low cost, etc., are widely used in various fields. However, most of motors are not used efficiently in many industries, since the loads are usually empty or light, which make the motor power factor and efficiency very low. This will not only waste a lot of energy, but also reduces the quality of electricity supply.Firstly, the motor power consumption are analyzed in the article, and then the relationship among power efficiency, power factor, smallest current and the slip ratio are analyzed as well. And then the components of the electricity fee are also given. Based on the theoretical analysis above, the optimal smallest input active power control method is chosen to control the motor. This method can not only reduce the active power, but also can effectively improve the power factor. Taking into account the changes in the electrical load, as well as the voltage vibration between morning and night, the method can adapt to find the best control curve automatically. The theory of active power of the motor in three-phase three-wire connection system is analyzed, which lay foundation on the final implementation of the smallest input active power control methodATmega16L is selected as the master controller; since its I/O port can provide 10 ~ 20mA source current and 40mA sink current, which can save a lot of peripheral driving circuit. Those functions, such as overload protection, open-phase protection and unbalanced three-phase fault protection are also implemented which can elongate the service life of the motor. Finally, a large number of experiments show that the energy-saving power controller is effective; the control system is stable and reliable with good prospects for promotion and application.