Common line communication in cascaded inverters

A method in a power inverter system, comprising:

• outputting, from a central unit, a command signal comprising switching commands;
• receiving the command signal at a plurality of switching units electrically connected in cascade configuration and adapted to receive a respective input DC power source voltage (VDC), each of the plurality of switching units including a bridge converter;
• operating at least some of the switching units in an inverter mode in which the bridge converters of the switching units are individually switched to produce a combined multilevel output voltage waveform (VOUT) that switches between different output levels, based on the switching commands, so that VOUT matches a desired sinusoidal voltage waveform (VAC) after filtering;
• during a silent period characterized as a flat step in VOUT between two consecutive switching commands of the command signal, operating at least one of the switching units in a communication mode in which the bridge converters of the at least one the switching units are switched a plurality of times between the two consecutive switching commands to produce a communication signal;
• outputting the communication signal superimposed on VOUT to a common line;
• and
• receiving, at the central unit, the communication signal.