Research On Control Technology Of Dual Three-Phase Permanent Magnet Synchronous Motors For Electric Vehicles Based On Model Prediction

In order to solve the problem of fossil energy shortage and environmental pollution,the development of electric vehicles with the advantages of energy saving and emission reduction,high efficiency and low noise,to replace traditional vehicles has become a general trend.The traditional three-phase transmission system is limited by the bus voltage and the power level of power electronic devices,and it is difficult to meet the low-voltage and high-power requirements.For this reason,the multi-phase transmission system with the advantages of small torque ripple,easy fault-tolerant control,low-voltage high-power output and high control freedom,is very popular in the field of electric vehicles.This dissertation takes dual three-phase permanent magnet synchronous motors(dual three-phase PMSM)as the object to study mathematical models,modulation algorithms and control strategies.First,the mathematical model of the dual three-phase PMSM in the natural coordinate system is established.Based on the vector space decoupling theory(VSD),the two-phase static and rotating coordinate coefficients model of the dual three-phase PMSM is derived.Verify the correctness of the model through simulation.Based on the idea of vector space decoupling,the vector distribution characteristics of the six-phase inverter are analyzed,and the maximum two-vector SVPWM modulation and four-vector SVPWM modulation are introduced.In view of the problem that SVPWM modulation cannot achieve four-dimensional current control,the nonlinear characteristics of the inverter,the air gap magnetic field of the motor and other factors are fully considered,and the double zero sequence injection PWM modulation strategy is further introduced to improve the utilization rate of the bus voltage.The effectiveness of the modulation algorithm is verified by simulation.In order to obtain faster dynamic response performance and reduce torque current ripple,the dead-beat current predictive control strategy of dual three-phase PMSM is studied.Through the comparison and simulation study with the traditional vector control method,the stability and feasibility of the deadbeat predictive control algorithm based on the q-axis current is verified.Aiming at the problem that deadbeat predictive control algorithms cannot effectively suppress harmonic currents,based on the space voltage vector distribution characteristics,with the suppression of current harmonics as the constraint,the model predictive control strategy of dual three-phase PMSM is studied,and the single virtual vector model predictive control strategy.This strategy constructs a new limited control set through reasonable combination of voltage vectors,optimizes the value function,and simplifies the design process of weight coefficients.Compared with traditional model predictive control,it has a small amount of calculation and can effectively suppress current harmonics.component.In order to further improve the steady-state performance of the motor in the low-speed region,the inherent one-beat delay is compensated,and the zero vector with different acting time is inserted to further suppress the current harmonics and improve the current following performance.With reference to the SVPWM modulation idea,a model predictive control strategy based on dual virtual vectors is introduced in the control of dual three-phase PMSM to improve the accuracy of fundamental wave sub-plane current tracking.Simulation research verifies the effectiveness of the predictive control algorithm for dual three-phase PMSM.Finally,an experimental platform for a dual three-phase PMSM drive system is built to verify the modulation algorithm and control strategy studied in this paper.The experimental results show the correctness and feasibility of the control method of the paper.