Multi-phase hybrid power converter architecture with large conversion ratios
View Patent ↗A multi-phase hybrid power converter architecture which provides high efficiency, high power density and high conversion ratios for non-isolated DC to DC power conversion. Hybrid converters are described in which a switched-capacitor network is interoperably merged with a switched-inductor network having multiple inductors, resulting in a circuit with reduced component count and in which soft-charging of the capacitors is performed. Multi-phase switching is utilized and includes a freewheeling state for output voltage regulation in which inductor current ramps down. The SC converter can be configured to provide various conversion ratios, such as 4-to-1, 6-to-1 and 8-to-1, and optimized for the needs of specific application.
1 . A DC-to-DC hybrid power converter apparatus, comprising:
(a) a switched capacitor (SC) network, having input and output terminals, merged with a switched inductor network as buck stages having buck stage interleaving, to form a combination configured for receiving a first DC voltage at an input of the apparatus and for outputting a second DC voltage at a given voltage gain, at an output of the apparatus;
(i) multiple flying capacitors in a series of capacitor stages, having an initial capacitor stage and outputs from final capacitor stages, in which the flying capacitors have at least two different voltage capacities as higher voltage capacitors and lower voltage capacitors;
(ii) a first plurality of switches at input sides of each capacitor stage, and a second plurality of switches to ground one terminal of each capacitor stage, and a third plurality of switches for coupling between inputs of the capacitor stages;
(iii) multiple inductors in a parallel connection of inductors, with inputs of the inductors coupled back to different capacitor stages;
(iv) a fourth plurality of switches coupling at least a portion of said inductors back to the different capacitor stages and a fifth plurality of switches coupling between an input of each of the multiple inductors to ground;
(v) outputs of the inductors are coupled together at an output of the hybrid power converter for driving an output load;
(b) wherein said DC-to-DC hybrid power converter apparatus is configured for being driven with multi-phase control signals within each switching cycle to a combination of said first, second and third plurality of switches within multiple states for the hybrid power converter, each switching cycle of which includes at least one freewheeling state for output voltage regulation where current through said parallel connection of inductors ramps down; and wherein all inductors in the buck stages are energized and de-energized in an interleaving manner with symmetrical phase shifts;
(c) wherein the lower voltage capacitors of the SC network are charged/discharged for more time than the higher voltage capacitors of the SC network toward maintaining flying capacitor charge balance; and
(d) wherein the final capacitor stages of said hybrid power converter are configured for being charged and discharged in a two phase operation in which the buck stage interleaving reduces switch component count.
2 . The apparatus of claim 1 , wherein voltage gain from the SC network is 4, 6, 8 times lower than said first DC voltage.
3 . The apparatus of claim 1 , wherein said multi-phase control signals comprise a group of at least 8 states in an 8-to-1 version, a group of at least 6 states in a 6-to-1 version, and a group of at least 4 states in a 4-to-1 version, in the multi-phase control signals with the at least one freewheeling state within each of these group of states for output voltage regulation where current through said parallel connection of inductors ramps down within each switching cycle.
4 . The apparatus of claim 1 , wherein said apparatus is configured to provide high conversion efficiency without requiring a large voltage conversion ratio at a second conversion stage.
5 . The apparatus of claim 1 , wherein said multi-phase operation is configured to achieve higher conversion ratios in the SC network, while improving efficiency and power density.
6 . The apparatus of claim 1 , wherein said multi-phase operation is configured for performing soft-charging capacitor operations toward reducing capacitor charge sharing losses.
7 . The apparatus of claim 1 , wherein said multi-phase control signals provide multiple charging and discharging states for said multiple flying capacitors.
8 . The apparatus of claim 1 , wherein a maximum number of buck stage inductors that can be utilized is equal to a conversion ratio of the SC network.
9 . The apparatus of claim 1 , wherein a number of buck stage inductors utilized is equal to a conversion ratio of the SC network divided by two or by four.
10 . The apparatus of claim 1 , wherein said first, second and third plurality of switches comprise transistor switches.
11 . The apparatus of claim 1 , wherein said DC-to-DC hybrid power converter apparatus is bidirectional, and can be utilized for either voltage step-down in which voltage gain is less than one, or voltage step-up in which voltage gain is more than one, by swapping the connections to the input and output terminals.
12 . A DC-to-DC hybrid power converter apparatus, comprising:
(a) a switched capacitor (SC) network, having input and output terminals, wherein the SC network is merged with a switched inductor network, to form a combination configured for receiving a first DC voltage at an input of the apparatus and for outputting a second DC voltage, at a given voltage gain, at an output of the apparatus;
(i) multiple flying capacitors in a series of capacitor stages in the SC network with initial capacitor stages connected from the input terminal of the SC network and proceeding to final capacitor stages preceding the merge with the switched inductor network, wherein the flying capacitors have at least two different voltage capacities as higher voltage capacitors and lower voltage capacitors;
(ii) a first plurality of switches, each of which is connected to an input side of its respective capacitor in the series of capacitor stages, and a second plurality of switches, each of which is configured to ground one terminal of its respective capacitor stage, and a third plurality of switches for coupling between inputs of the series of the capacitor stages;
(iii) multiple inductors in a parallel connection of inductors, with inputs of the inductors coupled back to different capacitor stages;
(iv) a fourth plurality of switches coupling at least a portion of said inductors back to the different capacitor stages and a fifth plurality of switches coupling between an input of each of the multiple inductors to ground;
(v) outputs of the inductors are coupled together at an output of the hybrid power converter for driving an output load;
(b) wherein said DC-to-DC hybrid power converter apparatus is configured for being driven with multi-phase control signals within each switching cycle, within each switching cycle, to a combination of said first, second and third plurality of switches within multiple states for the hybrid power converter, each switching cycle of which includes at least one freewheeling state for output voltage regulation where current through said parallel connection of inductors ramps down;
(c) wherein the lower voltage capacitors of the SC network are charged/discharged for more time than the higher voltage capacitors of the SC network toward maintaining flying capacitor charge balance, and said multi-phase operation is configured for providing multiple charging and discharging states for said capacitors and performing soft-charging capacitor operations toward reducing capacitor charge sharing losses;
(d) wherein the final capacitor stages of said hybrid power converter are configured for being charged and discharged in a two phase operation which allows a buck converter to be directly cascaded to said hybrid power converter without requiring additional switches; and
(e) wherein said multi-phase control signals comprise a group of at least 8 states in an 8-to-1 version, a group of at least 6 states a 6-to-1 version, and a group of at least 4 states in a 4-to-1 version, in the multi-phase control signals with the at least one freewheeling state within each of these group of states for output voltage regulation where current through said parallel connection of inductors ramps down within each switching cycle.
13 . The apparatus of claim 12 , wherein said apparatus is configured to provide high conversion efficiency without requiring a large voltage conversion ratio at a second conversion stage.
14 . The apparatus of claim 12 , wherein said multi-phase operation is configured to achieve higher conversion ratios in the SC network, while improving efficiency and power density.
15 . The apparatus of claim 12 , wherein a maximum number of buck stage inductors that can be utilized is equal to a conversion ratio of the SC network.
16 . The apparatus of claim 12 , wherein a number of buck stage inductors utilized is equal to a conversion ratio of the SC network divided by two or by four.
17 . The apparatus of claim 12 , wherein said first, second and third plurality of switches comprise transistor switches.
18 . The apparatus of claim 12 , wherein said DC-to-DC hybrid power converter apparatus is bidirectional, and can be utilized for either voltage step-down in which voltage gain is less than one, or voltage step-up in which voltage gain is more than one, by swapping the connections to the input and output terminals.
19 . A method of DC-to-DC power conversion, comprising:
(a) merging a switched capacitor (SC) network with a switched inductor network, to form a combination as a hybrid power converter, configured for receiving a first DC voltage at an input terminal and for outputting a second DC voltage at a given voltage gain, at an output terminal;
(b) coupling multiple flying capacitors in a series of capacitor stages, having an initial capacitor stage and final capacitor stages, in which the flying capacitors have at least two different voltage capacities as higher voltage capacitors and lower voltage capacitors;
(c) coupling a first plurality of switches an input side to each capacitor stage, and a second plurality of switches to ground one terminal of each capacitor stage, and a third plurality of switches for coupling between inputs of the capacitor stages;
(d) coupling multiple inductors in a parallel connection of inductors, with inputs of the inductors coupled back to different capacitor stages;
(e) coupling, using a fourth plurality of switches, connecting at least a portion of said inductors back to the different capacitor stages, and a fifth plurality of switches coupling between an input of each of the multiple inductors to ground;
(f) coupling the outputs of said inductors together at the output of the power converter for driving an output load;
(g) wherein said switched capacitor (SC) network merged with the switched inductor network is configured for being driven with multi-phase control signals within each switching cycle, within each switching cycle, to a combination of said first, second and third plurality of switches within multiple states for the hybrid power converter, each switching cycle of which includes at least one freewheeling state for output voltage regulation where current through said parallel connection of inductors ramps down;
(h) wherein the lower voltage capacitors of the SC network are charged/discharged for more time than the higher voltage capacitors of the SC network toward maintaining flying capacitor charge balance; and
(i) wherein the final capacitor stages of said hybrid power converter are configured for being charged and discharged in a two phase operation which allows a buck converter to be directly cascaded to said hybrid power converter without requiring additional switches.
20 . The method of claim 19 , wherein a maximum number of buck stage inductors that can be utilized is equal to a conversion ratio of the SC network.