High performance control of a three-level IGBT inverter fed AC drive

Three-level PWM inverters have been increasingly employed in industry and traction applications where high power and efficiency energy conversions are required. This paper presents a high performance control of a cage induction motor drive fed by a 100 hp three-level IGBT inverter operating at a low switching frequency. A practical mathematical model of the drive control system is established to aid in the control design to improve the system stability, dynamic performance and robustness over a wide speed range. The modeling and the simulation in Matlab/Simulink facilitate the self-tuning of the regulators in the multi-loop systems. The field oriented control and three-level space-vector modulation together with the drive protection and diagnostics are implemented in software based on a DSP TMS320C31. Experimental results based on the IGBT inverter prototype are given to verify the design and performance. Test results in motor common-mode voltage reduction and inverter neutral-point potential control are also briefly presented