Power balanced cascaded multilevel inverter fed scalar controlled induction motor pump sourced from photovoltaic source

Recent researches on cascaded H-bridge multilevel inverters (MLI) have led to its application for photovoltaic (PV) fed inverters for static isolated loads. The topology provides transformer less operation where separate DC links at each bridge are fed from individual PV units. The traditional control techniques using battery supported PV panels lead to non uniform operation and utilization of each H-bridge, where some bridges are under high stress as compared to others. Moreover, application to isolated dynamic loads likes pumps require variable voltage variable frequency(VVVF) control together with power balanced operation for sustainable operation. The paper presents control techniques which provide PWM gating pulses for VVVF control of inverter, power balance operation of induction motor in constant V/f control with storage element only supporting transient operation, and rotation of gating pulses for operation of each bridge at each level with uniform utilization of generated power by PV arrays of same capacity and same size of battery. Simulated results under MATLAB environment are presented to validate the effectiveness of the control scheme under varying insolation levels.