A novel control scheme for medium voltage drives operated by optimized pulse patterns

Tow Level- and Three Level- Voltage Source Converters are widely distributed in Medium Voltage Drives for traction and industry. Usually these converters are operated at low switching frequencies to maximize the converter power. To improve the quality of the output voltages and currents optimized pulse patterns are often applied in these applications. In recent publications a closed loop-control including a trajectory tracking method was introduced. This paper introduces a new control scheme, which enables the usage of optimized pulse patterns or PWM for low rotational speeds. It shows a linear system behavior in the complete drive operating range. Simulations and experimental results of a 4-kW drive verify the function and the excellent performance of the new control concept.