Universal power conversion methods with disconnect after driving
Methods and systems for transforming electric power between two or more portals. Any or all portals can be DC, single phase AC, or multi-phase AC. Conversion is accomplished by a plurality of bi-directional conducting and blocking semiconductor switches which alternately connect an inductor and parallel capacitor between said portals, such that energy is transferred into the inductor from one or more input portals and/or phases, then the energy is transferred out of the inductor to one or more output portals and/or phases, with said parallel capacitor facilitating “soft” turn-off, and with any excess inductor energy being returned back to the input. Soft turn-on and reverse recovery is also facilitated. Said bi-directional switches allow for two power transfers per inductor/capacitor cycle, thereby maximizing inductor/capacitor utilization as well as providing for optimum converter operation with high input/output voltage ratios. Control means coordinate the switches to accomplish the desired power transfers.
1. A method for power conversion, comprising the repeated sequential actions of:
a) applying voltage from a first external power connection, with a first polarity, to a parallel inductor/capacitor combination while said inductor/capacitor combination is disconnected from a second external power connection;
b) disconnecting said inductor/capacitor combination from both said first and second external power connections;
c) connecting said inductor/capacitor combination to said second external power connection to output power therethrough;
d) disconnecting said inductor/capacitor combination from both said first and second external power connections;
e) applying voltage from said first external power connection, with a second polarity which is opposite to said first polarity, to said parallel inductor/capacitor combination while said inductor/capacitor combination is disconnected from a second external power connection;
f) disconnecting said inductor/capacitor combination from both said first and second external power connections;
g) connecting said inductor/capacitor combination to said second external power connection to output power therethrough; and
h) disconnecting said inductor/capacitor combination combination from both said first and second external power connections.
2. The method of claim 1 , wherein said first external power connection is polyphase, and said steps a and b are repeated twice in alternation, from different phases, before said step c is performed.
3. The method of claim 1 , wherein said second external power connection is polyphase, and said steps c and d are repeated twice in alternation, into different phases, before said step e is performed.
4. A power converter, comprising:
a parallel inductor/capacitor combination, having first and second terminals;
a first external power connection, reversibly connected to said first and second terminals through respective phase legs each comprising two bidirectional switches;
a second external power connection, reversibly connected to said first and second terminals through respective phase legs each comprising two bidirectional switches; and
control circuitry which, whenever said inductor/capacitor combination has been connected to one of said external power connections, completely disconnects said inductor/capacitor combination from all external power connections before connecting said inductor/capacitor combination to another of said external power connections.
5. A power converter, comprising:
a transformer shunted by a capacitor;
a first external power connection, reversibly connected to a first and a second terminal of said transformer through respective phase legs each comprising two bidirectional switches, but not to a third nor a fourth terminal thereof;
a second external power connection, reversibly connected to said third and fourth terminals through respective phase legs each comprising two bidirectional switches, but not to said first and second terminals; and
control circuitry which, whenever said transformer has been connected to one of said external power connections, completely disconnects the combination of said transformer and said capacitor from all external power connections before connecting said combination to another of said external power connections.