| Permanent magnet synchronous motor(PMSM)has been widely used in many fields because of its advantages such as simple structure,low loss,high power density and high efficiency.Speed regulating system of PMSM represented by electric vehicle requires a wide range of speed,while PMSM can not be running above the rated speed for a long time controlled by traditional vector control method,so fluxweakening control is needed to broaden the speed range.In this paper,the method of flux-weakening control based on the dual current regulators and the single current regulator are used to study the weak magnetic control of PMSM vector control system.Firstly,the physical model and mathematical model of PMSM are introduced.On this basis,the principle and current control strategy of PMSM vector control are analyzed and the basic principle and digital realization method of SVPWM are analyzed in detail.Then the voltage and current constraints of PMSM vector control are elaborated.The principle and strategy of flux-weakening control are analyzed in detail and the three operation area of flux-weakening control is given.And then,the basic principle of advanced angle flux-weakening control based on dual current regulators and the parameter setting method of the regulators are analyzed.On this foundation,the simulation model is built in MATLAB/Simulink environment and the simulation results show that the proposed method can effectively improve the speed range and has a certain load carrying capacity in weak magnetic field.The theoretical analysis shows that regulator coupling is serious when PMSM is adopted double current regulators flux-weakening control running at high speed.Aiming at this problem,a flux-weakening control method based on single current regulator is adopted,trying to use the current coupling phenomenon.Firstly,the principle of fixed q-axis voltage control is analyzed and the static and dynamic performance is discussed.Because the q-axis voltage is fixed,it can not run in the optimal point,which will reduce the load capacity and efficiency.On this foundation,this paper introduces a variable q-axis voltage single current regulator flux-weakening control method,which solves the problem of fixed q-axis voltage control.The control ability is analyzed and the switching condition of flux-weakening control is given.Finally,the simulation model is built in MATLAB/Simulink environment and the simulation analysis is carried out.The results show that single current regulatorflux-weakening control can solve the problem of current coupling and the variable q-axis voltage single current regulator flux-weakening control has a strong load carrying capacity and higher efficiency than the fixed q-axis voltage single current regulator flux-weakening control.Finally,the system experiment platform is built and the software is designed.On this basis,an experiment of advanced angle flux-weakening control based on dual current regulators is conducted.The experimental results are consistent with the simulation results. |
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