Three-phase AC to DC isolated power conversion with power factor correction
An isolated, power factor corrected, converter, for operation from a three-phase AC source, comprises three power processors, each power processor connected to one of the three phases. Each power processor comprises a cascade of a first and a second power conversion stage. At least one of the first and second power converters in each power processor is configured to provide galvanic isolation through a DC Transformer between the power processor input and output. At least one of the first and second power converters in each power processor is configured to provide power factor correction at the AC source. Substantially all of the bulk energy storage and low frequency filtering is provided by storage elements at the output of the power system. Low voltage semiconductor devices may be cascaded to implement low output capacitance high voltage switches in a multi-cell resonant converter for high voltage applications.
1. An apparatus for converting power received from a source for delivery to a load, the apparatus comprising:
a two-stage power processor having a processor input adapted to receive power at a processor input voltage, V1-in, from the source and a processor output for delivering power to the load, the two-stage power processor including a first switching power conversion stage and a second switching power conversion stage;
the first switching power conversion stage including a plurality of input cells connected to receive power from the processor input and a plurality of outputs connected to deliver power to the second switching power conversion stage, each input cell having a respective input for receiving power at an input voltage, Vin, and each input cell having a respective one or more power switches and a respective primary winding connected to convert power received from the respective input for delivery to a respective output via a secondary winding magnetically coupled in common with each of the primary windings to form a multi-winding transformer; and
a switch controller constructed and arranged to operate the first switching power conversion stage in a series of converter operating cycles with an essentially fixed voltage transformation ratio, K=V1out/V1in;
the plurality of input cells including a number, n, of input cells,
the inputs of the n, input cells being connected in series across the processor input to divide the processor input voltage, V1-in, among the input cells such that Vin=V1-in/n;
the second switching power conversion stage comprising a plurality of switching regulators, each having a respective regulator input connected to receive power from a respective first stage output, a respective second stage output connected to deliver power to a system output, and a respective one or more power switches;
the second switching power conversion stage comprising one or more switch controllers constructed and arranged to operate the one or more power switches to regulate the second stage output;
wherein the outputs of the switching regulators are connected in parallel with each other to deliver power to the load.
2. The apparatus of claim 1 wherein the one or more power switches include primary switches in each of the plurality of input cells that include a maximum voltage rating, Vdevmax, that is 80 volts or lower.
3. The apparatus of claim 1 , wherein the one or more power switches include primary switches in each of the plurality of input cells that include a maximum voltage rating, Vdevmax, that is 100 volts or lower.
4. The apparatus of claim 1 , wherein the one or more power switches include primary switches in each of the plurality of input cells that include a maximum voltage rating, Vdevmax, that is 120 volts or lower.
5. The apparatus of claim 1 , wherein the one or more power switches include primary switches in each of the plurality of input cells that include a maximum voltage rating, Vdevmax, that is 60 volts or lower.
6. The apparatus of claim 1 wherein the number, n, of input cells is 3 and each of the plurality of input cells includes primary switches of the one or more power switches that experience a maximum stress that is Vin/3 or lower, where Vin is the processor input voltage.
7. The apparatus of claim 6 wherein each of the primary switches experiences a maximum stress that is Vin/6 or lower, where Vin is the processor input voltage.
8. The apparatus of claim 1 wherein the number, n, of input cells is 3 and an output voltage V1out of each cell is Vin/6 or lower, where Vin is the processor input voltage.
9. The apparatus of claim 1 wherein the number, n, of input cells is 3 and a first stage output voltage, V1out is equal to Vin/6 or lower, where Vin is the processor input voltage.
10. The apparatus of claim 1 wherein the number, n, of input cells is 4 and each of the plurality of input cells includes primary switches of the one or more power switches that experience a maximum stress that is Vin/4 or lower, where Vin is the processor input voltage.
11. The apparatus of claim 10 wherein each of the primary switches experiences a maximum stress that is Vin/8 or lower.
12. The apparatus of claim 1 wherein the number, n, of input cells is 4 and an output voltage V1out of each cell is Vin/8 or lower, where Vin is the processor input voltage.
13. The apparatus of claim 1 wherein the number, n, of input cells is 4 and a first stage output voltage, V1out is equal to Vin/8 or lower, where Vin is the processor input voltage.
14. The apparatus of claim 1 further comprising a bulk storage device connected to the outputs of the plurality of switching regulators.
15. The apparatus of claim 1 , comprising:
one or more energy storage devices connected to a common output of the plurality of switching regulators;
wherein the outputs of the switching regulators are connected in parallel to deliver power to the common output to supply power to the load.
16. The apparatus of claim 1 , comprising:
the first switching power conversion stage configured and arranged to convert power received from a first stage input via the multi-winding transformer, the first stage output being galvanically isolated from the first stage input,
the first switching power conversion stage including the one or more power switches comprising:
one or more primary power switches connected to drive the multi-winding transformer;
one or more secondary power switches connected to rectify power received from the multi-winding transformer,
the switch controller adapted to provide signals to turn the one or more primary power switches ON and OFF in a series of first converter operating cycles to convert power via the transformer at an essentially fixed ratio, K-Vin/Vout, from the first stage input for delivery at a unipolar voltage to the first stage output, the unipolar voltage characterized by a periodic ripple having a characteristic frequency and a characteristic period.