Static inverter with energy return

摘要

In a static inverter for providing a low-frequency output (e.g. 60 Hz) from a d.c. supply, the passage of low-frequency currents through the inverter transformer is avoided by producing a train of high- frequency pulses (e.g. 40 kHz) which represent, for example by their pulse widths, the successive instantaneous amplitudes of the required low- frequency voltage. These pulses cause a train of corresponding pulses to be produced at the secondary of the transformer, and this train is filtered to produce a unidirectional voltage having the desired instantaneous amplitudes. This voltage is fed to a transistor switching bridge which changes the unidirectional voltage into an alternating voltage having the required low frequency. A circuit is preferably provided to allow regeneration of power from the load back into the d.c. supply.