Wireless load sharing of single phase telecom inverters

Telecom systems demand high availability DC power and the battery plant was developed to satisfy that demand. While a case can be made that all telecom loads should be powered from the DC source, the fact remains that today´s telecom systems rely on AC powered equipment for all sorts of monitoring and control functions. This equipment is just as critical as the DC load, thus high availability AC power is also needed. Supplying this AC is not easy as the utility grid is prone to outages and transients while standard UPS systems usually require a separate battery plant and still fall short on availability. A key reason that AC inverters have not achieved the availability of DC converter systems is the problem of isolation and redundancy. While straightforward in DC systems, the four quadrant operation of inverters along with the need for phase matching complicates the solution for AC systems. Common synchronizing and control circuits are normally required to parallel inverters but these common circuits are vulnerable to single fault scenarios that can bring down the whole system. This paper describes a means to improve the isolation and redundancy of multiple-inverter systems by eliminating the common synchronizing and control circuits