Research On Vector Control System Based On Optimal Excitation Current For Three-phase Asynchronous Motors

With the continuous development of modern power electronics and microprocessor technology, theinduction motor speed control technology is in rapid development because of the limitations of the DC speedcontrol system and superiority of AC drive system. High-performance vector control system allows controlperformance of ordinary AC induction motor has been close to or above the DC motor speed control systemand has significant energy savings. Nowadays widely used in induction motor speed control system technologyincludes VVVF, vector control oriented at rotor flux, direct torque control and so on. Research in this paper isa three-phase induction motor vector control technology. Vector congtrol has superior dynamic performanceand low-speed performance.In this paper, three-phase asynchronous motor static and dynamic mathematical model was elaborated,pointing out three-phase asynchronous motor is a strong coupling, multi-variable nonlinear systems. Analysisof the most critical algorithm coordinate conversion technology in vector control. discusses the differencesbetween direct vector control and indirect vector control, feedback, feedforward two voltage decouplingmethod.In order to improve the efficiency of three-phase asynchronous motor, vector control system based onoptimal excitation current for three-phase asynchronous motors is studied by j-k coordinate orientation. j-kaxis orientation angle leads the traditional dq axes45. So when the three-phase stator current is transformatedafter Clarke and Park transformation, the output torque is controlled on the j-axis and k-axis current. When theoutput current is equal, this method can increase the output torque of the motor.Traditional vector control and optimal excitation current vector control were studied experimentally.Hardware in Experimental system is mainly for over-current protection circuit, power tube drive circuit, speedand phase current sampling circuit. Software gives the authentication method of major parts in the vectorcontrol algorithm. Experimental results demonstrate the optimal excitation current vector control algorithmrunning at low speed in good condition and has a certain energy-saving features running at no-load or lightload.