| Due to its excellent output characteristics,permanent magnet synchronous machine(PMSM)has been widely used in limited space and efficiency oriented working environment,such as electric vehicles,robots,etc.In an electromechanical system,the system vibration noise caused by motor is one of the main components of system noise.The vibration and noise of motor is caused by internal and external factors,one is that the motor torque will produce torque ripple with the change of rotor position angle due to the influence of non-sinusoidal flux linkage and cogging torque;the other is due to the high-frequency current fluctuation caused by the high-frequency interruption of bus voltage in pulse width modulation,thus producing high-frequency vibration noise.These noises make the riding experience of passengers worse,so this paper will carry out the research on torque ripple suppression of motor according to the above key problems.First of all,the current compensation design is carried out in this paper.By adding compensation current to the reference current,the additiona l torque ripple and the inherent torque ripple of the motor are offset each other.In order to design harmonic compensation current,it is necessary to obtain the corresponding torque information.Therefore,in order to approximate the torque of the real motor,based on the finite element model parameters of the motor,the torque data are trained and the torque observer model is built.According to the relationship between torque and current,the torque information obtained by the observed torque is transformed into single order compensation current,and then the composite reference current is obtained.Under the condition of zero steady state error control of current,the designed compensation current will produce torque harmonics with the same amplitude and opposite phase as the inherent torque fluctuation of the motor,which will counteract the inherent torque ripple of the motor,so as to minimize the torque ripple of the motor.In order to realize the zero steady-state error control of the resultant current,the controller is designed according to the characteristics of the resultant current.In practice,the resultant current contains many frequency components,repetitive controller and model predictive controller are used to control the composite curren t of multi frequency components.According to the requirements of different working conditions of the motor,the disadvantages of the traditional repetitive controller and model predictive controller are overcome,and the repetitive controller can be applied to control the signal when the fundamental frequency changes Because of the disadvantage of MPC’s computational load,the computational complexity of MPC is greatly reduced by selecting the vector number of MPC.In order to verify the suppression effect of the proposed algorithm for torque ripple,a motor control verification platform with d SPACE as the main control system is built.Under different operating conditions of the motor,the effectiveness of the torque ripple suppression method is verified by realizing the better tracking characteristics of the composite current under different operating conditions. |
