Patent ID: 6465912
Filing Date: 2002-10-15
Classification: H02J

Abstract:
A power transfer device comprising:a first current transferring section connected between a first AC power source and a load, the first current transferring section switching current flow from the first AC power source to the load; a second current transferring section connected between a second AC power source and the load, the second current transferring section switching current flow from the second AC power supply to the load, the second current transferring section including first and second switches having respective current conducting directions, and connected in parallel and in reverse polarity; a current detector for detecting a current flow from the first AC power source to the load, the current detector outputting a detection signal; a power transfer signal generator for generating a power transfer signal for transfer of the load from the first AC power source to the second AC power source, the power transfer signal setting the first current transferring section to stop current flow from the first AC power source; a current direction estimator, responsive to the power transfer signal and the detection signal, estimating direction of a remaining current flow from the first AC power source to the load at a time when the second current transferring section first begins supplying current from the second power source by closing one of the first and second switches; and a conduction signal generator, responsive to the direction of the remaining current flow estimated by the current direction estimator, first closing the one of the first and second switches that supplies a current from the second AC power source that cancels the remaining current then flowing from the first AC power source to the load, and, thereafter, closing the other of the first and second switches to, whereby current flow through the first current transferring section is rapidly extinguished and the first and second AC power sources are not short-circuited during switching.