Gradient Based Hysteresis Current Control – A Parameter-Free Current Control Method for Highly Utilized PMSM Drives

This paper presents an adaptive parameter-free current control method with variable switching frequency using a finite control set (FCS) for high dynamic current control of permanent magnet synchronous machines (PMSM). The method allows the control of electrical machines even with high nonlinear flux linkage as it occurs in highly utilized traction drives. By evaluation of inverter induced current ripple and identification of the switching state dependent current gradient and absolute current value, the system state can be determined. Since this identification takes place during operation and hence matches the recent operation point, the control does not need classical parameters and therefore becomes insensitive to parameter errors. This paper provides a detailed description of the control method and the implemented switching state dependent identification of the system state. Simulation results of the control algorithm in combination with measurement results of the system state identification proof the feasibility of the proposed control scheme.