Inverter having center switch and uninterruptible power supply implementing same

摘要

Presented is a center switching circuit and an inverter and an uninterruptible power supply (UPS) utilizing same. The center switching circuit selectively enables and disables power flow to and from the bus capacitors of an inverter or UPS. As such, the center switching circuitry effectively removes the bus capacitors from the circuit. This allows operation of the inverter or UPS in a high efficiency mode whereby input line voltage may be passed essentially without compensation to the output when the center switching circuit is open. Modulation of the center switching circuit during this mode provides soft charging of the bus capacitors so that they are available to source current in a double-conversion or DC boost mode upon degradation or loss of the line voltage. To supply output power from the bus capacitors, the center switching circuit is closed to associate these capacitors with the neutral. Fault isolation is provided during operation by opening the center switching circuit to prevent power flow from the bus capacitors.