The Study Of Energy-saving Control System For AC Motors

This year, with the rapid development of the national economy, China’s energyconsumption is increasing rapidly. Energy is one of the most serious waste, and theasynchronous machine is a electrical equipment of high-energy consumption,which ismostly used in a broader range. The asynchronous motor is in the under-loading or theiding working conditions, appears the asynchronous machine power factor to becomelower, the efficiency reduced, the electrical energy wasted and other serious consequences.Therefore, to improve the operating efficiency of the motor can greatly relieve the energyshortage, it is realistic significant for us to improve the efficiency of the national economy.The paper first take the asynchronous machine under-loading efficiency becominglower reason as a starting point, the detailed analysis of the asynchronous machine energyconsumption relations, and gives through controlling the copper loss and iron loss of theasynchronous machine to achieve the appropriate proportions to achieve optimizateefficiency of motor. Afterwards, has carried on the depth analysis to determine the theenergy-saving working point of the asynchronous machine, the optimal operating point ofthe motor is based on the principle of minimum loss todetermine the optimal statorfrequency of the motor and the excitation voltage, thus it can be energy-saving controlledfor the asynchronous machine. The paper has carried on the analysis to sensor-lessfield-oriented control system, has eliminated that the speed sensor bring all the trouble,and improved the reliability of the system.In the foundation of the above theoretical anaiysis, the system hardware circuit designand the software algorithm design have completed. In the hardware design, including themain control chip selection (80C196KC), A/D converter module selection, the main circuitdesign, the drive circuit design, the testing circuit design, the power supply design and thekeyboard and the display circuit design and so on. In the software design, each mainfunction module detail flowchart and PI algorithm have given, also introduced in thissubsystems design software and hardware anti-interruption measures.Finally, it experiments for maximum efficiency of the asynchronous machine, throughchanging the frequency or voltage of the motor to study the variation of operatingefficiency of the motor, to explore the control principle of maximum operating efficiencyunder the power matching, and process analysis, it verifies practicality of the methods.The system also simulates speed identification which has adopted model reference adaptive method to achieve sensor-less field-oriented control.