The Grid Side EL And The Machine Side DTC Control Of The Asynchronous Motor

In the conventional induction motor speed control system,the suitable direct voltage is selected directly at both ends of the inverter,the direct current is inverted into the alternating current after the internal three-phase inverter bridge,and the induction motor is finally driven and controlled.With the actual needs of production and daily life and work tasks,it is more and more important to select a suitable controllable DC voltage across the inverter while ensuring the accuracy of speed-driven induction motors.In order to achieve the controllability of DC voltage,the three-phase PWM converter is introduced into the induction motor network side,and different control strategies are selected to obtain the controllable DC power.Induction motors,as the converter of electrical energy and mechanical energy,mainly consider the efficiency and rotational speed problems.There are many control methods of induction motors and the neural network control programming is complicated,which may result in long running time.The traditional sliding mode control can make the motor reach the expectation rapidly,the steady-state,although stable after the existence of jitter problems,but you can choose a different sliding mode control law to reduce the chattering problems.In this paper,the controllable DC voltage and energy are obtained from the induction motor inverter,and the motor system is controlled under the optimal energy condition.First of all,the three-phase PWM converter is introduced to obtain the controllable DC voltage,and the three-phase AC voltage is output via the inverter to realize the speed control of the induction motor.The research work in this paper is mainly focused on:Firstly,induction motor is taken as the control object,three-phase PWM converter is introduced,the EL model of PWM converter is established by EL control method,the equilibrium point of the system is selected and the energy injection molding method is also adopted to design the system EL controller to get a controllable DC output voltage,and finally prove the system stability through the theory of passivity.Induction motor is still the object of control.In order to obtain a more flexible and controllable DC output voltage,the converter control method is improved.The EL control and sliding mode control are combined.The EL control of the converter is used as the current The inner loop and sliding mode control can track the given voltage quickly as the voltage outer loop,and the controller of EL control and sliding mode control can be obtained by calculation to get the controllable DC output voltage.Lastly,the system stability is proved by the theory of passive.According to the research of induction motor speed control,the basic control objectives are: to design the load torque observer considering the unknown load torque of induction motor;in the traditional direct torque control of induction motor,PI speed loop control Parameter fixed,low torque and large flux ripple problem,put forward to improve the control strategy.That is,the external speed loop takes the terminal sliding mode control to obtain the desired electromagnetic torque and uses the actual measured torque as the input of the internal hysteresis control to obtain the sector selection signal,and then outputs 6-way according to the sector selection signal PWM control signal,the ultimate realization of induction motor precise speed control.The simulation results show that the designed sliding mode and EL control can provide suitable DC voltage for the control circuit of asynchronous motor.The control of asynchronous motor can be controlled by the machine-side terminal sliding mode and direct torque control method.