Predictive Current Controller for Inverter Fed Medium Voltage Drives with LC Filter

The switching frequency of power semiconductor devices in high power medium voltage drives is limited because of high switching losses. These drives often comprise an LC output filter. The filter introduce a resonant circuit that may be excited for instance by fast control transients. One option to avoid such oscillations is applying damping control methods, which on the other hand usually require switching frequencies well above the filter resonance. This paper presents a new predictive stator current controller that avoids the excitation of the filter resonance, realizes active damping and enables fast current control while maintaining low switching frequency. Feasibility and good dynamic performance of the proposed control method is demonstrated by simulation results of a 2.4 kV induction motor drive and by experimental results obtained from a 55 kW prototype a.c. drive.