Buck-boost power converter circuits, methods and systems
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 power conversion circuit, comprising:
an input stage which repeatedly, at various times, drives current into the parallel combination of an inductor and a capacitor, and immediately thereafter temporarily disconnects, on every inductor cycle, said parallel combination from all external connections, to thereby transfer some energy from said inductor to said capacitor;
wherein said action of driving current is performed in opposite senses and various times, and wherein said disconnecting operation is performed substantially identically for both directions of said step of driving current; and
an output stage which extracts energy from said parallel combination to thereby perform power conversion.
2. The converter of claim 1 , wherein said input stage comprises a full-bridge array of switches.
3. The converter of claim 1 , wherein said input and output stages each comprise a full bridge array of switches, and are symmetrically connected to said parallel combination of the inductor and the capacitor.
4. The converter of claim 1 , wherein said input and output stages each selectably connect said parallel combination of the inductor and the capacitor to a low-impedance voltage source/sink.
5. The converter of claim 1 , wherein said parallel combination of the inductor and the capacitor comprises a transformer.
6. A power conversion circuit, comprising:
an input stage which repeatedly drives current into the parallel combination of an inductor and a capacitor, and immediately thereafter temporarily disconnects, on every inductor cycle, said parallel combination from all external connections, to thereby transfer some energy from said inductor to said capacitor; wherein said input stage drives current in different senses at different times; and
an output stage which repeatedly couples power out of said parallel combination, and immediately thereafter temporarily disconnects, on every inductor cycle, said parallel combination from all external connections, to thereby transfer some energy from said inductor to said capacitor; wherein said output stage couples power out of said combination during two opposite directions of current therein;
wherein said input and output stages both disconnect said parallel combination substantially identically for both directions of current in said combination.
7. The circuit of claim 6 , wherein each said driving action is performed using multiple different drive pulses from different legs of a polyphase power line.