Research On Model Reference Adaptive Control Of Permanent Magnet Synchronous Motor With Variable Inertia

The high power density of permanent magnet motor makes it more and more widely used in AC servo system.In many applications of servo,the inertia of load will change greatly at any time or in working conditions,which greatly increases the difficulty of servo control.In order to improve the robustness of the variable-inertia load servo system,based on the model reference adaptive control,this paper makes an indepth study on improving the response rapidity,robustness and parameter adaptability.The mathematical model of ac permanent magnet motor system is established.A feedforward compound control scheme of position loop is proposed to improve the speed of position response and optimize the dynamic performance of position response.The relationship between rotational speed,position loop bandwidth and rotational inertia is established,the influence of rotational inertia on rotational speed and position control performance is analyzed,and the effect of rotational inertia on control performance and the difficulty of controller design are summarized.A robust model reference adaptive position control strategy is adopted for the position response overharmonic oscillation introduced by the inertia change,which is independent of the precise modeling of the mechanical parameters of the motor.Two improvements on the traditional algorithm are proposed,the dynamic performance of the traditional algorithm is improved by introducing the feedforward part,and the control loop is added with proportional-differential correction control to get good control effect.The step response of variable inertia is simulated under different algorithms,and the performance indexes of step response under different control strategies are extracted for comparative analysis,which verifies the effectiveness of the proposed algorithm.Aiming at the robustness requirements of speed control,an error model reference adaptive speed control strategy with error model is proposed.The error equation is used to form the reference model,and the parameter variation is compensated by adaptive feedback,thus reducing the parameter dependence.The variable inertia simulation of the proposed control strategy is carried out,and the good effect of the algorithm is verified under large inertia,load inertia and strong load disturbance.The relationship between position gain and inertia after position closed loop is analyzed,which provides a foundation for the subsequent design of self-tuning algorithm.Aiming at the adaptive requirements of position response under the change of inertia,based on the speed adaptive controller proposed,an adaptive position control scheme based on parameter identification algorithm is proposed by introducing the inertia identification algorithm.The load inertia is estimated online by least square identification with forgetting factor,which provides a basis for self-tuning of position loop parameters.The relationship between the maximum bandwidth constraint and the position loop gain is derived and the traditional self-tuning scheme is improved.The online and semi-off-line position loop self-tuning-MRAC control strategies based on maximum bandwidth constraints are designed respectively,which greatly improve the dynamic performance of position control under the inertia variation.