Research On Torque Control And Speed Estimation For Induction Motors Based On Instantaneous Torque Theory

In recent years,the new energy vehicle industry has developed rapidly,which has put forward high requirements for motor drive systems.Motor drive control technology,as an important component of motor drive systems,has also received increasing attention from scholars.The main research direction of motor drive control technology is to improve the dynamic and steady-state operating performance of the system,as well as to improve the dynamic and steady-state performance of speed sensorless control systems.Among various types of drive motors,induction motors are widely used due to their simple structure,stable operation,and low cost.Firstly,for the problem that the motor models used in conventional fieldoriented control,direct torque control,and instantaneous power control cannot fully describe the dynamic process of the motor,based on the amplitude/frequency theory,this paper takes the dynamic process of rotating magnetic field of induction motor as the research object.Starting from the instantaneous power equation,the concept of instantaneous torque is derived,and the relationship between input signal,rotating magnetic field and output torque during the induction dynamic process is described by using the concept of instantaneous torque,so that the dynamic process of the motor can be directly described by the instantaneous reactive/active torque.so that the dynamic process of the motor can be directly described by the instantaneous reactive/active torque.Secondly,in order to obtain the steady-state characteristics similar to the field-oriented control and the dynamic characteristics similar to the direct torque control,based on the instantaneous torque theory,this paper selects the amplitude of the rotating magnetic field and the rotation angle frequency as the output variables,derives the state space equation of the instantaneous torque of the induction motor,and expounds the physical significance of the equation.Furthermore,in order to achieve linearization control,a simplified feedback linearization control struction is proposed,which simplifies the design process and avoids zero dynamic problems.Meanwhile,to further improve the torque response speed,instantaneous torque feedback has been setThen,when the motor is running,the model reference adaptive speed estimation algorithm based on reactive power has large steady-state speed error,large torque ripple,and large current harmonics.In response to these issues,based on the theory of model reference adaptive systems,this paper constructs an adaptive speed estimator using instantaneous torque,and constructed a slip angle frequency calculation model by the stator flux amplitude and instantaneous active torque,then,a model reference adaptive speed estimation algorithm based on instantaneous torque is established.Finally,experimental verification was conducted on an induction motor experimental platform based on a rapid control prototype controller.The experimental results show that the torque response speed of the proposed algorithm is 30% faster than field oriented control and 10% faster than direct torque control.The torque ripple of the proposed algorithm in steady-state is65% lower than field-oriented control and 84% lower than direct torque control.Therefore,the used torque control algorithm for induction motors based on the instantaneous torque model has better dynamic and steady-state performance.Compared to conventional speed estimation algorithms based on reactive power model reference adaptive systems,the used speed estimation algorithm based on instantaneous torque model reference adaptive systems has better control performance,with a reduction of 38.7% in dynamic overshoot,61.5% in steady-state speed error,10% in torque ripple,and 38.2% in stator current harmonics.Therefore,the used algorithm can effectively reduce steady-state speed error,torque ripple,and current harmonics.