The Research On Efficiency Optimization Of Vector Control System For Induction Motors

Induction motors have been widely used in industrial applications due to its advantages of simple structure, easy manufacture and reliablility. Most efforts have been put on improving speed regulation performance and simplifying the system structure in the previous studies of induction motor drive systems. However, induction motor drive systems consume quite a lot of electricity power in the whole society. And there is still a lot of work to do for energy saving in induction motor drive systems. Due to the concerns of energy crisis and the trend of energy conservation, studying the energy conservation of induction motor drive systems is very important.The losses of induction motors during operation mainly consists of copper loss, iron loss, mechanical loss and stray loss. Among them, the copper loss and iron loss can be optimized by control strategy. So they are called the controllable losses, accounting for 80% of the total loss. The controllable losses are the main interest of research of energy-saving induction motor drive systems. Conventional induction motor multivariate mathematical model ignores the iron loss. So it does not apply to energy conservation drive control systems. To observe and study the losses of induction motors, to further improve the accuracy of the model, it is necessary to establish a mathematical model of the induction motor considering the iron loss.In various control algorithms of induction motor speed control system, the vector control has advantages of a wide speed regulation range and good dynamic performance. However, at light load conditions, the induction motor under vector control still operates with a low efficiency, causing serious energy waste problem. To solve this problem, the induction motor vector control system was redesigned under the motor model considering the iron loss. Then the maximum efficiency control strategy based on optimal flux was applied. The optimal flux value that allows the induction motor running with maximum efficiency was calculated at a certain speed and load conditions. The optimal flux value was set as the given value for the flux regulator to obtain energy-saving induction motor vector control system based on optimal flux.The energy-saving induction motor vector control system simulation model was built in MATLAB/Simulink environment. The performance of flux observer, speed regulation, energy efficiency and anti-disturbance were tested and studied. While on the AC speed control system experimental platform, taking TI company’s DSP TMS320F2812 as the controllor, the YS5624 G three-phase squirrel cage induction motor as the study object, the experimental study of energy-saving induction motor vector control system was carried out.