The Research On Speed Sensorless Control Of Induction Motor And Nonlinear Compensation

The demand for induction motor is growing day by day,and the control demand of it is increasingly strictly.Speed sensorless vector control system has become the induction motor usual control methods for its excellent performance in AC speed regulating system,then decouple the stator current,thus make the system get the excellent dynamic performance.But in the process of the operation of the induction motor current flow can generate heat and impact resistance of rotor resistance,influence on the side of the stator flux estimation,lower the accuracy of the speed estimation,so the high performance of control system depend on high accurate identification of rotor resistance.Therefore,the speed sensorless vector control system of the stator and rotor resistance identification is very necessary.According to the above questions,this article adopts full order state observer adaptive control,simplify the feedback matrix to accelerate the convergence rate,achive the rotor resistance and the speed of recognition,eliminated the precision problem that caused by the change of rotor resistance in the process of identification of induction motor speed.Due to the full order state observer is able to identify rotor resistance and speed at the same time,simplified the identification,saving the cost of the use on hardware.In addition,considering the reason of cost and precision in induction motor control,using space vector pulse width modulation module to replace the stator voltage output voltage,But in order to prevent the inverter bridge arm straight and join the dead zone of time,although time is very short,but with the passage of time can cause accumulation effect,especially in the voltage source inverter in low frequency and light load makes the motor phase current and phase voltage distortion,rotational speed and torque ripple,lower the system performance degradation.In order to improve the performance of the system,we take measures to compensate the dead zone.Dead zone compensation first computing the error of control cycle time,then calculate the corresponding relationship between electric current and the error time,finally will compensate the cycle error voltage to the inverter input voltage.By compensating error voltage,reducing the effect on the control system of current harmonic,and improved energy utilization efficiency of the grid side.