Patent ID: 7339806

Claim:
An adjustment device for adjusting a wave shape of an output of a DC-AC inverter, comprising (a) a feedback circuit; the feedback circuit including: a transformer having a primary terminal for connection to an alternating current output of the DC-AC inverter; a capacitance; and a rectifier; the rectifier being connected to a secondary terminal of the transformer; the rectifier being connected in parallel to the capacitance at output terminals thereof; (b) a microcontroller having a built-in analog-to-digital converter; the microcontroller being connected to both an output terminal of the feedback circuit and to the DC-AC inverter for receiving a voltage signal detected by the feedback circuit and using the voltage signal to measure an output voltage of the DC-AC inverter, and providing feedback-control the DC-AC inverter for allowing the DC-AC inverter to provide a stable fixed AC voltage output; and (c) a zero-crossing detector having an input coupled to the fixed AC voltage output and an output coupled to the microcontroller, the microcontroller using the output of the zero-crossing detector to control the frequency of the DC-AC inverter and thereby adapt the output of the DC-AC inverter for a parallel connection with another DC-AC inverter.