초록 ▼

A power source provides continuous AC power by employing a bi-directional converter which interfaces a rechargable DC power storage device with AC mains power and AC loads. The bi-directional converter includes a transformer having first and second windings coupled in reverse polarity through dual s

A power source provides continuous AC power by employing a bi-directional converter which interfaces a rechargable DC power storage device with AC mains power and AC loads. The bi-directional converter includes a transformer having first and second windings coupled in reverse polarity through dual switching means in parallel with one another. The switching means are coupled to a state controller responsive to conditions at the AC mains terminal, the AC load terminal and the DC power terminal. There are two general operating conditions, an active condition wherein DC power is provided to the AC load, and a standby condition wherein power is recovered by the DC storage device. In the standby condition, the converter operates in a so-called “flyback”mode to recover power and to direct it to the DC storage device. In the active condition, the converter is pulse-width modulated according to a predetermined duty cycle to produce an AC sine wave output at the AC load terminals. Where the AC load includes reactive components, the converter operates to recover unused power from the load and to transfer power back to the DC power source whenever the polarity of the output voltage differs from the polarity of the output current.

대표청구항 ▼

An apparatus having first and second DC power terminals for use in transferring electric power between an AC power system and a DC power storage device, such as a battery, said apparatus comprising: a push-pull transformer having a first winding for interfacing with said AC power system, and a secon

An apparatus having first and second DC power terminals for use in transferring electric power between an AC power system and a DC power storage device, such as a battery, said apparatus comprising: a push-pull transformer having a first winding for interfacing with said AC power system, and a second winding, said second winding having a first end tap, a second end tap and a center tap, said center tap being coupled to said first DC power terminal; a flux storage transformer capable of storing flux for a period which is large compared to a switching frequency of current through said flux storage transformer comprising a third winding and a fourth winding, said third winding being in a first current path with third and fourth end taps and said fourth winding being in a second current path with fifth and sixth end taps, said third and fifth end taps having the same polarity, said third end tap being coupled in said first current path to said first end tap of said push-pull transformer and said sixth end tap being coupled in said second current path to said second end tap of said push-pull transformer, said fourth end tap being coupled in said first current path to said second DC power terminal and said fifth end tap being coupled in said second current path to said second DC power terminal; first bi-directional switching means in said first current path; second bi-directional switching means in said second current path; means for pulse width modulating said first switching means and said second switching means on and off to direct current flow in said first and second current paths in a first direction to said first and second DC power terminals; said first and second switching means each including a diode which is responsive to a forward bias in said first and second current paths, respectively, to permit current flow only in a second direction in said first and second current paths, respectively, through said first and second DC power terminals, said second direction being the reverse of said first direction; said modulating means being constrained to modulate only said first switching means or only said second switching means so as to define a permissable current path alternately (a) from said second DC power terminal in said first direction through said first current path into said third winding of said flux storage transformer in order to generate a flux, which, upon opening of said first switching means, induces a current in said fourth winding in said second direction through said second current path back to said second DC power terminal without reversing current flow polarity in said first winding of said push-pull transformer, or (b) from said second DC power terminal in said first direction through said second current path to said fourth winding of said flux storage transformer in order to generate a flux, which, upon opening of said second switching means, induces a current in said third winding in said second direction through said first current path back to said second DC power terminal without reversing current flow polarity in said first winding of said push-pull transformer, such that the duty cycles of said switching means determine whether net DC power flow is from or to said DC power terminals.