Modified Scalar Control for Improved Performance of Cascaded H-Bridge Five-Level Inverter-fed Induction Motor Drive

Conventional scalar control for induction motor drives (IMD) using a two-level converter has the advantage of simple control but suffers from sluggish speed response and poor power quality. This study presents a scalar control employing a modified integrator-based proportional-integral (MIPI) controller with an integrator initial value and drift control for dynamic performance improvement. The MIPI involves a logical implementation to update the integrator output to reset the integrator and update the output within the designated sampling time for effective control. Because the delay associated with feedback control also degrades the performance, an additional loop is used that holds the previous sample output and triggers the PI controller. Additionally, a phase opposition disposition (POD) carrier-based cascaded H-bridge five-level inverter is used to improve the current and voltage harmonics performance of the IMD. The proposed scheme is also validated using a laboratory experimental setup of a 2.2 kW IM drive coupled with a DC generator for electrical loading.