Abstract: The invention relates to a converter which can operate as a rectifier to rectify alternating current into direct current running in one direction (for example to charge batteries) or a converter where DC (from the batteries) can be converted to AC and supplement AC power, for example to supplement an alternator output in peak load conditions. The converter comprises a uni-directional electrical energy source (battery) and a bi-directional energy source (small battery bank connected for reverse direction current flow, capacitor or fuel cell) which is capable of initiating an alternating current when controlled by thyristors fired in sequence and with such periods that a sine wave can be simulated. The switches are controlled by a thyristor trigger logic current control unit which may for example be a micro processor.