| 摘要 |
<p>The present invention synthesizes an approximation to a 60 Hz sine wave using a plurality of bursts of high frequency square waves. The number of square wave cycles in each burst is modulated to achieve a good approximation to a sine wave. This bipolar burst train is then separated into two complementary unipolar burst trains, which are fed to power transistors to modulate current at the primary of a transformer. Since the transformer is not required to withstand saturation over a full half cycle at 60 Hz, but only over a half cycle at the square wave frequency, the transformer weight can be greatly reduced, as can the number of primary turns. Two secondary windings are used, each coupled to a single output stage, and an npn/pnp pair of transistors, controlled by the 60 Hz reference, provides polarity switching to restore full-cycle ac output power.</p> |
