Research On AC Motor Vector Control System Based On Phase Current Reconstruction

The current reconstruction method based on single DC-link current sensor can effectively reduce the cost and volume of AC variable frequency speed regulation system,and is suitable for low cost applications.But there is a problem of this method that is the failure of phase current reconstruction in unobservable regions.Aiming at solving this problem,the current reconstruction method based on single DC-link current sensor is studied in this paper.In this paper,the basic theory of vector control is introduced and the direct vector control system is established by the rotor flux orientation method.The principle and realization of continuous voltage space vector pulse width modulation(CSVPWM)and discontinuous voltage space vector pulse width modulation(DSVPWM)are analyzed.And the control system is simulated by MATLAB/Simulink.Then,under the two modulation modes:CSVPWM and DSVPWM,this thesis introduces the basic principle of current reconstruction based on single resistance sampling.Aiming at the problem that the phase-current reconstruction by pulse shift method can't realize phase current reconstruction within some special areas,this paper puts forward a method of phase current reconstruction based on effective vector insertion.In this method,the duty cycle of the PWM which is inserted by effective vector is compensated,so that the resultant voltage vector remains unchanged.The feasibility of the proposed method is verified by simulation.Finally,the real-time simulation system of vector control based on phase current reconstruction of the effective vector insertion is built.The designs of this system include the hardware circuit design and the real-time transformation of the off-line simulation model.Then,the ControlDesk software is used to online debug the control system.The experimental results show that the proposed phase current reconstruction method is effective in the two modulation modes of CSVPWM and DSVPWM.