Research On Self- Adaptive Electrical Tool

As a machine that can transfer electrical energy into mechanical energy, electrical tool has been used more and more widely in daily life and industrial field. How to change the motor speed according to different load is a very important study subject in power electronics. This article is about how to use power electronictechnique combined with IGBT to build a system that can change the output torque of motor automatically when the load changes.In order to achieve adaptive control of electric tools, sensor-less technology was used to estimate the speed of electric tools, takes the estimate speed as a feedback variable, built a closed-loop speed regulation of electric tools.During the course of this project, the author has completed the following work and achieved some useful results.(1)According to the voltage equations and flux linkage equations of motor in two-phase stationary coordinate system, there are two forms of rotor flux model based on different variables. One is called the current model which contains variable speed and the other one is called voltage model which doesn't contain this variable. A self-adaptive system with speed estimation model was built by using the calculated electromagnetic torque as the error output.(2)Having analyzed the specific requirements of frequency control system, a design idea was proposed and the hardware design was completed, including main circuit, control circuit and corresponding input and output circuits.(3)Based on the hardware platform, combination of software programming the speed closed-loop adjustment function was achieved. successfully made power tools change adaptively to adjust the load speed.(4)Last but not least, the system was simulated on the Matlab7.1 to test speed estimation model and performance of the system. The results evidenced that estimated speed can vary according to the set speed. At the same time, the system has good speed stability and dynamic response too.