A variable frequency drive system (300) includes a power converter (310) with a plurality of power cells supplying power to one or more output phases (A, B, C), a main power source (320) for providing main input power to the power converter (310), an auxiliary power source (330) for providing auxiliary input power to the power converter (310), and a control system (314) in communication with the power converter (310) and controlling operation of the plurality of power cells, wherein the control system (314) comprises one or more processor(s) (315) configured via computer executable instructions to detect a main input voltage drop of the main power source (320) below a predefined power threshold, disconnect the main power source (320) in response to the main input voltage drop, and enable the auxiliary power source (330) to provide auxiliary input power to the power converter (310) in response to the main input voltage drop.