Research On Direct Torque Control Strategy Of Permanent Magnet Synchronous Hub Motor

In the 21 st century,China’s rapid economic development,national car penetration are also constantly improve,so generates a lot of energy depletion and the problem of environmental protection.So the electric car industry is going to be booming.Permanent magnet synchronous motor(PMSM)is a kind of permanent magnet synchronous motor(PMSM)applied on the wheel hub,which is favored by vehicles due to its advantages.In this paper,direct torque control strategy(DTC)is directly applied to the motor to improve the control effect of the whole system through some control improvement measures.In this paper,some basic structures and mathematical models of PMSM are firstly discussed in detail,and various coordinate transformations of PMSM mathematical models are also described,which are also needed in the following sections.Secondly,the traditional DTC algorithm,principle,mathematical model and advantages and disadvantages are described in detail.MATLAB/Simulink software is used to completely show the traditional DTC simulation model,and the simulation results show that the DTC system has a good performance in dynamic and static performance.It’s good for vehicle speed,but that doesn’t mean it’s perfect.It also has some unsatisfactory performance at low speed,such as torque ripple and flux fluctuation and switch loss.In order to solve the problem in this paper,we introduced the model prediction methods of direct torque control(MPDTC)prediction model is established by the method,and the predictive control delay compensation,at the same time,in view of the voltage vector optimization using the value function,function contains parameters such as torque ripple and the flux pulsation index,at the same time to the index of weight,eventually make the output voltage vector selection is optimal.In this way,the torque ripple is reduced and the problems of large torque ripple and unstable low speed of the system are solved.The simulation results show that the system has good performance,and the torque ripple can be reduced obviously at low speed,and the excess switching loss can be reduced at the same time.Finally based on the traditional DTC system and MPDTC system did not solve the problem of stator flux pulsation is larger,the introduction of the duty cycle modulation strategy for research,the use of torque and flux of zero voltage vector and deviation analysis under the action of non zero voltage vector of the stator flux linkage amplitude and rate of change of electromagnetic torque to calculate the duty ratio,combined with MPDTC was improved,make the vehicle all-digital fuzzy DTC system further to improve performance in low speed.Figure[122]Table[5]reference[80]...