| 摘要 |
An inverter is powered by the pulsed DC voltage obtained by unfiltered full-wave rectification of the 60 Hz voltage from a regular electric utility power line. As long as the magnitude of the DC supply voltage is higher than a certain threshold level, the inverter can be triggered into 30 kHz self-sustaining oscillation. However, this oscillation stops as soon as the magnitude of the DC supply voltage falls below this certain threshold level. Thereafter, the inverter will not restart its oscillation, regardless of the magnitude of the DC supply voltage, except if provided with another trigger signal. Thus, the inverter can be made to operate in fashion analogous to that of a thyristor: Once triggered, the inverter will provide a 30 kHz output of magnitude substantially proportional to that of its DC supply voltage; but as soon as the magnitude of its DC supply voltage decreases below a certain threshold level, as indeed occurs once every half-cycle of the 60 Hz voltage, it will cease to provide an output. To provide a substantially continuous output of 30 kHz voltage, the inverter has to be triggered each half-cycle of the 60 Hz voltage, the trigger phasing being determinative of the RMS magnitude of the output voltage. If continuous triggering is not provided, no 30 kHz output voltage results. Means are provided by which the triggering and its phasing are controlled electrically, thereby providing for an inverter with electrically controllable output voltage.
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