Dc-link Cueernt Control Of Permanent Magnet Synchronous Motor System Driven By Current Source Inverter

The motor drive system can be divided into voltage source inverter(VSI)topology and current source inverter(CSI)topology based on the type of power supply used on the DC side.Compared to VSI,CSI has the advantages of high reliability,high-quality output current waveform,inherent short-circuit protection function and expanding the constant power operation range of motors.However,CSI systems typically use a voltage source in series with an inductor to achieve constant current output,which can cause intermittent or continuous increases in DC-link current.Therefore,this paper adopts a DC-DC converter circuit and designs a PI controller to control the DC-link current.At the same time,a detailed analysis was conducted on the voltage variation between the DC-DC converter and the CSI within a cycle.By optimizing the current vector sequence of the CSI,the ripple of the DC-link current was suppressed,thereby reducing inductor and switching losses,and improving the current waveform quality of the output motor.Through simulation and experiments,it has been proven that the proposed control strategy is feasible and effective.The main research content of this paper is divided into the following four parts:1.Firstly,the topological structure of the CSI driven permanent magnet synchronous motor system was analyzed,and models of the three-phase permanent magnet synchronous motor in two different coordinate systems were established.Then,a mathematical model of the CSI permanent magnet synchronous motor system,including filter capacitors,was established.2.Based on the characteristics of the CSI three-phase permanent magnet synchronous motor system model,a multi-loop controller was designed using a feedforward decoupling strategy.The active damping method is used to solve the problem of parallel resonance between the CSI output capacitor and the stator inductance of the permanent magnet synchronous motor,which improves the stability of the system.At the same time,based on the modulation principle of CSI and referring to the modulation of VSI,the space vector pulse width modulation of CSI system is achieved.3.In response to the problem of discontinuous DC-link current in traditional CSI topology,a DC-DC converter circuit was used to realize DC-link current control.The ripple of the DC-link current was suppressed by optimizing the current vector sequence.Simulation analysis was conducted in Matlab to verify the correctness of the proposed method in this paper.4.A CSI three-phase permanent magnet synchronous motor system experimental platform was built with TMS320F28377 S as the main control chip.The software and hardware implementation principles of this experimental platform were briefly introduced,and experiments were designed to verify the DC-link current control method of the CSI driven permanent magnet synchronous motor system proposed in this paper.