Search

US-12627227-B2 - Switched-bus based resonant switched-capacitor converter architecture

US12627227B2US 12627227 B2US12627227 B2US 12627227B2US-12627227-B2

Abstract

A cascaded converter architecture comprising a pure switched-capacitor (SC) stage and a resonant SC stage. Multiple switching buses are utilized to connect the first-stage SC converter with second-stage multi-phase resonant SC converters. The flying capacitors of both stages are resonant with the output inductors, so the charge distribution loss is eliminated. Zero-current switching is realized by adjusting the duty ratio and switching frequency. By using the intermediate switching bus, the number of switches can be reduced, and the intermediate bus capacitor is not required; thereby greatly reducing component count and cost while improving power density. Numerous implementation variations are described by way of example and not limitation.

Inventors

  • TING GE
  • Zichao Ye
  • Yicheng ZHU
  • Robert C.N. Pilawa-Podgurski

Assignees

  • THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

Dates

Publication Date
20260512
Application Date
20230613

Claims (20)

  1. 1 . A resonant switched-capacitor converter apparatus, the apparatus comprising: a first-stage comprising a switched-capacitor (SC) converter; and a second-stage comprising at least one multi-resonant switched-capacitor (SC) converter; wherein the second-stage is connected to the first-stage through at least one intermediate switching bus; and wherein said apparatus is a 4-to-1 resonant switched-capacitor converter comprising: wherein the first stage is configured with a 2-to-1 step down conversion ratio in which power is received and passed through parallel switches connected to a first capacitor, wherein on an output side of the first capacitor is another pair of parallel switches whose outputs are mid-converter outputs, mid1 and mid2; wherein the second stage comprises two phases of 2-to-1 step down converters, each receiving one of the mid-converter outputs to a second capacitor, an other end of which is coupled through a switch to ground; and wherein each output side connection of the second capacitor passes through a switch and then are connected to a common inductor having an output connected between the two phases of the second stage, and coupled to output capacitors for driving a load at the output of the 4-to-1 resonant switched-capacitor converter.
  2. 2 . The apparatus of claim 1 , wherein said first-stage comprises a pure switched-capacitor (SC) stage; and said second-stage comprises a multi-phase resonant switched-capacitor (SC) stage; and wherein the at least one switching bus intermediates between said first-stage and said second-stage.
  3. 3 . The apparatus of claim 1 , wherein the first-stage comprises two switches and one flying capacitor.
  4. 4 . The apparatus of claim 1 , wherein the second-stage comprises two circuit phases, and wherein each said phase of the second-stage comprises three switches, one flying capacitor, and one resonant inductor.
  5. 5 . The apparatus of claim 1 , wherein the first-stage and the second-stage each operate with two phases of switching control.
  6. 6 . The apparatus of claim 1 , wherein the apparatus is driven with pulse-width modulation (PWM) drive signals.
  7. 7 . The apparatus of claim 1 , wherein switching frequency and duty ratio in controlling switching of said first and second stage circuitry approximately matches a resonant frequency of inductor-capacitor (LC) tank circuits operated by different operating phases within said first and second stages.
  8. 8 . The apparatus of claim 1 , wherein the at least one intermediate switching bus, providing multiple mid-converter outputs, connects between the first-stage switched-capacitor (SC) converter and the second-stage having multiple phases of resonant switched-capacitor (SC) converters.
  9. 9 . The apparatus of claim 1 , wherein the first-stage and the second-stage include flying capacitors that share output inductors to provide soft charging.
  10. 10 . The apparatus of claim 1 , wherein the first-stage has an integer value N step down ratio and integer value of K outputs.
  11. 11 . The apparatus of claim 1 , wherein the second-stage has an integer value M step down ratio.
  12. 12 . The apparatus of claim 1 , wherein each first-stage output is connected to one phase circuit in the second-stage.
  13. 13 . The apparatus of claim 1 , wherein a switch, or switches, at each first-stage output are switched on only when corresponding connected phase circuit of the second-stage is operating in an operating phase of obtaining energy from the at least one intermediate switching bus.
  14. 14 . The apparatus of claim 1 , wherein the at least one intermediate switching bus has a plurality of outputs, each of which provide a phase shift.
  15. 15 . The apparatus of claim 1 , wherein the first-stage is implemented using a switching-capacitor topology selected from the group of topologies consisting of Dickson, Series-Parallel, and Fibonacci.
  16. 16 . The apparatus of claim 1 , wherein the first-stage and the second-stage are each controlled by two periodic phase signals, wherein in a first half cycle of a period switches are activated for charging an LC tank circuit, while in a second half cycle of the period the LC tank circuit is discharged into the load.
  17. 17 . The apparatus of claim 16 , wherein the first stage and the second stage are synchronized and operated by drive signals at an identical switching frequency.
  18. 18 . The apparatus of claim 17 : wherein a duty ratio, D, of the drive signals is determined by a ratio of resonant frequencies at different operating phases; and wherein zero-current switching is provided when a switching frequency matches a resonant frequency.
  19. 19 . The apparatus of claim 1 : wherein the first-stage has an integer value N step down ratio and an integer value of K outputs, wherein power is input through switches, connected in series to each of an integer value of K phase circuits; wherein each said switch of an integer value of a first K−1 circuit phases connects to a first end of a flying capacitor for that circuit phase; wherein series switches and grounding switches, for each circuit phase of the first K−1 circuit phases, are coupled from a second end of each flying capacitor to one of multiple mid-converter outputs; and wherein a final K circuit phase receives power from a last of the switches connected in series, and passes this through a series switch to its respective phase circuit output.
  20. 20 . The apparatus of claim 1 , wherein the second-stage comprises an integral number M of circuit phases to provide an integral step-down ratio of M.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to, and the benefit of, U.S. provisional patent application Ser. No. 63/354,143 filed on Jun. 21, 2022, incorporated herein by reference in its entirety. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with Government support under Award Number DE-AR0000906, awarded by the U.S. Department of Energy, Advanced Research Projects Agency-Energy (ARPA-E). The Government has certain rights in the invention. NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION A portion of the material in this patent document may be subject to copyright protection under the copyright laws of the United States and of other countries. The owner of the copyright rights has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the United States Patent and Trademark Office publicly available file or records, but otherwise reserves all copyright rights whatsoever. The copyright owner does not hereby waive any of its rights to have this patent document maintained in secrecy, including without limitation its rights pursuant to 37 C.F.R. § 1.14. BACKGROUND 1. Technical Field The technology of this disclosure pertains generally to bus voltage converters, and more particularly to a cascaded converter architecture using multiple switching buses to connect a first-stage converter with second-stage converters. 2. Background Discussion Cloud-based computing, powering neural networks, memory storage, block chain computing, and high bandwidth communications show continued growth, necessitating improvements in data center power management. The available space for the motherboard or accelerator card is usually limited, while the power consumption of CPU/GPU/ASIC chips is increasing continuously. To meet the stringent requirements of space and power, extremely compact and efficient power converters are demanded. Specifically, a high-performance intermediate bus converter is needed to step down from a 48 V DC voltage to an intermediate bus voltage (usually ranging from 4 to 12 V) in data center power delivery. Conventional cascaded converters rely on an intermediate DC bus voltage that reduces flexibility and the ability to achieve high step-down conversion efficiencies. Accordingly, a need exists for a converter architecture which overcomes these conventional converter issues. The present disclosure fulfills that need and provides additional benefits over existing conversion systems. BRIEF SUMMARY This disclosure describes a cascaded converter architecture comprising a pure switched-capacitor (SC) stage and a resonant SC stage. Unlike conventional cascaded converters with an intermediate DC bus voltage, this converter uses multiple switching buses to connect the first-stage SC converter with second-stage multi-phase resonant SC converters. The flying capacitors of both stages are resonant with the output inductors, so the charge distribution loss is eliminated. Zero-current switching is realized by adjusting the duty ratio and switching frequency. By using the intermediate switching bus, the number of switches can be reduced, and the intermediate bus capacitor is not required; thereby greatly reducing component count and cost while improving power density. Examples of applications in which the technology of this disclosure can be useful include, but are not limited to: (i) data center power delivery (from 48 Volts to 6-12 Volts) to support the fast increasing power demand of AI, IoT and so forth; (ii) all-electric and hybrid vehicles to bridge 48V distribution and legacy 12V legacy subsystems; (iii) portable electronics to enable more efficient and faster wired/wireless charging; and (iv) solar photovoltaics to improve the conversion efficiency between solar panels and the grid. Further aspects of the technology described herein will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the technology without placing limitations thereon. BRIEF DESCRIPTION OF THE DRAWINGS The technology described herein will be more fully understood by reference to the following drawings which are for illustrative purposes only: FIG. 1 is a block diagram of a resonant switched-capacitor converter with an intermediate switching bus, according to at least one example embodiment of the present disclosure. FIG. 2 through FIG. 4 are circuit diagrams of a 4-to-1 cascaded resonant converter having a first-stage 2-to-1 SC block with each output connected to a 2-to-1 resonant SC block, according to at least one example embodiment of the present disclosure. FIG. 5 through FIG. 7 are operating state diagrams for the three operating states of the converter shown in FIG. 4, according to at least one example embodiment of the present disclosure. FIG. 8 is a waveform diagrams of Inductor currents, intermedi