Current Predictive Vector Control Schemes Of Permanent Magnet Synchronous Motors

In recent years,permanent magnet synchronous motor(PMSM)has been widely used in the field of modern industry due to its high efficiency and energy saving advantages.However,the steady-state accuracy of traditional direct torque control is low and the dynamic response of traditional vector control is slow.As a high performance control solution of PMSM drive system,model predictive control(MPC)system is significant and practical value in modern industry,which also conforms to Chinese policy in energy saving and environmental protection.Non-salient-pole PMSM driven with sine wave is studied in this paper.To improve the dynamic response and steady-state accuracy,an on-line dead-time compensation method based on the traditional vector control and space vector pulse width modulation(SVPWM)in PMSM drive systems is discussed.And current predictive vector control schemes of PMSM are studied.The details are listed as follows:On the basis of the operating principle of PMSMs,the mathematic model of PMSMs are deduced in three coordinate systems.The rotor field oriented vector control of PMSM and the realization process of SVPWM are analyzed.The traditional vector control scheme of PMSM is is tested and verified in computer simulation.Due to dead-time effect in voltage source inverter(VSI)driven PMSM systems,there are some serious problems such as current distortion,torque fluctuation and the additional power loss,et al.In this paper,time duration error of switching devices and voltage error of the output phase-voltage caused by dead-time effect are analyzed in detail.And then an on-line dead-time compensation method based-on q-axis current error in PMSM drive systems is proposed,combined with the zero d-axis current reference vector control.This proposed method doesn't need an accurate model of motor-inverter system and any additional hardware circuit.The MATLAB/Simulink simulation results verify that this on-line compensation strategy can mitigate current distortion effectively.Current prediction vector control of PMSM can achieve better control performance,where the current PI loop in the vector control is replaced by the current predictive control.Three current prediction vector control schemes are analyzed,including direct predictive current control(DPCC),two-vectors predictive current control(2PCC)and deadbeat current control.Simulation results verify that they can all improve the control performance effectively.And the deadbeat current control shows the fastest dynamic response and the highest steady-state accuracy.Finally,an experimental comparison of the traditional dead-time compensation and the on-line compensation schemes proposed in this paper are adopted.And experimental results verify that this on-line compensation strategy can mitigate speed fluctuation and current distortion effectively.Furthermore,an experimental comparison of the traditional vector control and the deadbeat current control is adopted.And the experimental results confirm that this deadbeat current control can realize faster dynamic response and higher steady-state accuracy.