Development of DTC for Induction Motor Fed with Multilevel Inverter & Improved PWM Control Strategy to Maximise Energy Efficiency in EV/HEV/FCV

To maximize efficiency and drivability of EV/HEV/FCV,an improved software and hardware architecture is developed. Four node cluster based microcontroller configuration is built for running V/f, DTC and FOC algorithms on three different nodesin parallel to deliver real time torque and speed demand of vehicle in start-stop, acceleration and cruising mode respectively. This paper presents development of Direct Torque Control (DTC) algorithm to drive induction motor which will run on proposed parallel computing environment. DTC is implemented with conventional 3 level, 5 level symmetric and 7 level asymmetric inverterconfigurations. In order to minimize THD content in output voltage of inverter when operated with DTC mode, new PWM control strategy is developed. This has helped in obtaining DTC advantages with more Torque /Ampere and thus making this control efficient as close to FOC. Both symmetric and asymmetric multilevel inverter prototypes are developed and implemented with improved software and hardware architecture to run induction motor in transient conditions.Results are compared with DTC implemented with 3 level inverter and demonstration is done to show improvement in State of Charge (SoC) and other performance related parameters of battery. This exercise is carried out as a part ofimproving energy efficiency of full parallel HEV configuration for a passenger car application.