Patent ID: 8432714

Claim:
A method of balancing load between parallel connected inverter modules arranged to supply a common load, the method comprising: providing switching instructions for the parallel connected inverter modules; determining, based on the phase currents of each parallel inverter module, a first time period for each output phase of each inverter module for correcting current imbalance by advancing or delaying turn-on or turn-off time instants of switch components of the inverter modules; advancing or delaying the turn-on or turn-off time instants of the switching instructions based on the first time period; determining temperatures of each output phase of each inverter module; modifying the switching instructions for at least one of the parallel inverter modules for correcting a temperature imbalance between parallel inverter modules by comparing the temperatures of corresponding output phases of each parallel inverter module with one another, determining, for each output phase of each inverter module, a second time period for correcting a temperature imbalance between output phases of each inverter module based on the comparing, and advancing or delaying the turn-on or turn-off time instant based on a sum of the first time period and the second time period while continuing to operate the inverter modules; and controlling the inverter modules with the modified switching instructions while continuing to operate the parallel inverter modules; wherein the first time period has a predetermined maximum value common to each output phase, the method further comprising limiting a maximum value of the first time period based on a value of the second time period.