In a three phase microgrid, due to asymmetric loading of the individual phases, the phase currents are unequal. This results in appreciable negative sequence and zero sequence current through the phases, which may falsely trip the line circuit breakers and damage three phase machines which are connected to the microgrid. Several inverter topologies like four half bridges and three separate full bridges, are being investigated to compensate for this unbalance, such the power quality and reliability in the microgrid is maintained. At PEMSES, we are working on developing several PWM techniques and control methods using four leg inverter to compensate for the negative sequence and zero sequence current.
