Extensible multi-inductor center-fed dc buck converter

Abstract

This invention discloses a scalable multi-inductor centrally located DC-DC buck converter, comprising a voltage input terminal, a pre-stage series capacitor conversion unit, a multi-inductor assembly, a post-stage switched capacitor conversion unit, and a voltage output terminal, all electrically connected in sequence. The pre-stage series capacitor conversion unit includes multiple series capacitors and multiple power switches, used to perform series voltage division on the input DC voltage, forming multiple voltage divider nodes. The multi-inductor assembly stores energy between the pre-stage series capacitor conversion unit and the post-stage switched capacitor conversion unit to achieve energy coupling and maintain continuous current. The post-stage switched capacitor conversion unit includes multiple switched capacitor conversion branches, used to perform switched capacitor conversion on the voltage output by the inductors and supply power to the voltage output terminal. This invention improves energy transfer capability under high current conditions by forming voltage divider nodes with pre-stage series capacitors and combining the synergistic energy transfer of multiple inductors and multiple switched capacitor branches.

Description

Technical Field

[0001] This invention belongs to the field of integrated circuit technology, and more specifically, relates to a scalable multi-inductor centrally located DC-DC buck converter. Background Technology

[0002] It is predicted that data center power consumption will enter a period of rapid growth over the next decade, reaching 13% of global power demand by 2030. This trend poses a serious challenge to energy efficiency, therefore, developing more energy-efficient and higher power density power transmission solutions has become a core task for the sustainable development of data centers.

[0003] As the power consumption of modern computing cores continues to rise, the energy efficiency shortcomings of traditional power supply architectures are becoming increasingly apparent, particularly with high-power microprocessors such as CPUs, GPUs, and ASICs. Against this backdrop, the 48V bus architecture has gradually become the focus of the industry due to its two core advantages: significantly reducing energy loss during power distribution and improving the overall operating efficiency of the power supply system, with a much higher adaptability to high-power devices than traditional architectures. At the same time, the power supply demands of downstream loads are also constantly upgrading. Point-of-load converters (POCs) need to achieve both higher voltage conversion ratios and larger output currents in scenarios with ultra-low output voltages (typically below 1V) to meet the power supply requirements of high-power chips.

[0004] Currently, the industry has developed various 48V to 1V voltage conversion topologies, which can be mainly divided into two categories: single-stage conversion solutions and two-stage conversion solutions.

[0005] Among the two types of solutions, the single-stage conversion architecture has become the mainstream development direction due to its superior overall performance. Its core advantages include: high voltage conversion efficiency; strong power supply stability; rapid dynamic response; and lower device stress. The inductor-centered structure, in particular, has been widely studied due to its ability to reduce the DC component of the inductor and effectively separate high and low voltages. Furthermore, the inductor-centered structure is better suited for three-dimensional vertical power supply scenarios. By embedding the final-stage switched capacitor on the back of the active silicon substrate, it can improve the board-level transmission voltage, reduce current and losses, and enhance output capability, providing strong power support for the processor. However, the traditional inductor-centered structure does not support high-current expansion, limiting its output capability in processor power supply scenarios.

[0006] However, in processor power supply scenarios involving high-voltage input and ultra-low-voltage, high-current output, while existing inductor-centered converter structures can achieve energy isolation between the high and low voltage sides to some extent, their topologies often struggle to balance high voltage conversion ratios with scalable output current. As the input voltage increases further or the load current continues to grow, the current concentration and limited topology scalability issues in traditional structures become increasingly apparent, restricting their further application in high-power-density power supply scenarios. Therefore, there is an urgent need for a DC-DC buck converter topology that, within an inductor-centered energy transfer structure, can achieve graded input voltage processing and reduce current concentration through multi-path energy transfer, thereby addressing the limitation of output capability in high-current power supply scenarios. Summary of the Invention

[0007] To address at least one of the technical problems mentioned in the background art, this invention proposes a scalable multi-inductor centrally located DC-DC buck converter. This scalable multi-inductor centrally located DC-DC buck converter includes a voltage input terminal, a front-stage series capacitor conversion unit, a multi-inductor assembly, a rear-stage switched capacitor conversion unit, and a voltage output terminal, all connected in sequence. The voltage input terminal is used to connect to the input DC voltage; The front-stage series capacitor conversion unit includes multiple series capacitors and multiple front-stage power switching transistors electrically connected to the multiple series capacitors, and is used to perform series voltage division processing on the input DC voltage to form multiple voltage division nodes. The multi-inductor assembly is used to store energy between the front-stage series capacitor conversion unit and the rear-stage switched capacitor conversion unit to achieve energy coupling and maintain continuous current. The multi-inductor assembly includes multiple inductor elements, and the input terminal of each inductor element is electrically connected to the multiple voltage divider nodes respectively. The subsequent switched capacitor conversion unit includes multiple switched capacitor conversion branches, each of which is electrically connected to the output terminal of a corresponding inductor element. It is used to perform switched capacitor conversion on the voltage output by the inductor element and to supply power to the voltage output terminal. The voltage output terminal is used to output DC voltage to the load.

[0008] Optionally, the pre-stage series capacitor conversion unit adopts an N-stage topology, where N is a positive integer greater than 1; the pre-stage series capacitor conversion unit includes N-1 flying capacitors and 2N pre-stage power switching transistors; the multi-inductor assembly includes N inductor elements; The N-1 flying capacitors are connected in series between the voltage input terminal and ground; the input terminals of the N-1 inductors in the multi-inductor assembly are selectively connected to ground or the negative plate of the corresponding flying capacitor through the corresponding front-stage power switch, so as to realize the switching connection between different voltage divider nodes and the input terminals of the inductors; the input terminal of the Nth inductor is selectively connected to ground or electrically connected to the end node of the series chain of the N-1 flying capacitors through the front-stage power switch. The positive plates of the N-1 flying capacitors are interconnected through a front-stage power switch, and the positive plates of the N-1 flying capacitors selectively form an electrical path with the voltage input terminal and selectively form an electrical path with the input terminal of the Nth inductor through the front-stage power switch.

[0009] Optionally, the front-end power switch is a MOSFET device or an IGBT device.

[0010] Optionally, the subsequent switched capacitor conversion unit adopts an N-stage topology; the subsequent switched capacitor conversion unit includes N flying capacitors and 3N subsequent power switching transistors, forming N switched capacitor conversion branches; The positive plates of the N flying capacitors are electrically connected to the output terminals of the corresponding inductors in the multi-inductor assembly; the negative plates of the N flying capacitors are selectively connected to ground or the voltage output terminal through the corresponding power switching transistors; the positive plates of the N flying capacitors also form an electrical path with the voltage output terminal through the corresponding power switching transistors, so as to realize switched capacitor energy transfer of the output voltage through the charging and discharging of the flying capacitors.

[0011] Optionally, the voltage rating of the subsequent power switch is lower than that of the preceding power switch, the on-resistance of the subsequent power switch is less than that of the preceding power switch, and the switching speed of the subsequent power switch is greater than that of the preceding power switch.

[0012] Optionally, the pre-stage series capacitor conversion unit and the post-stage switched capacitor conversion unit operate at independent switching control frequencies, and the switching frequency of the post-stage switched capacitor conversion unit is higher than the switching frequency of the pre-stage series capacitor conversion unit.

[0013] Optionally, both the pre-stage series capacitor conversion unit and the post-stage switched capacitor conversion unit are cascadeable expansion structures, and the number of inductor elements in the multi-inductor assembly corresponds to the number of stages of the pre-stage series capacitor conversion unit and the post-stage switched capacitor conversion unit.

[0014] Optionally, when N=3, the pre-stage series capacitor conversion unit includes 2 flying capacitors and 6 pre-stage power switching transistors; the multi-inductor assembly includes 3 inductor elements; and the post-stage switched capacitor conversion unit includes 3 post-stage flying capacitors and 9 post-stage power switching transistors. Specifically, the left ends of the three inductors are selectively connected to ground or the negative plate of the corresponding flying capacitor in the pre-stage series capacitor conversion unit via corresponding pre-stage power switches; the positive plates of the flying capacitors in the pre-stage series capacitor conversion unit are connected to each other via pre-stage power switches, and are selectively connected to the voltage input terminal and the left end of the final stage inductor via pre-stage power switches; the negative plate of the flying capacitor in the post-stage switched capacitor conversion unit is selectively connected to ground or the voltage output terminal via post-stage power switches; the positive plate of the flying capacitor in the post-stage switched capacitor conversion unit is electrically connected to the left end of the corresponding inductor, and is electrically connected to the voltage output terminal via post-stage power switches.

[0015] Optionally, when N=4, the pre-stage series capacitor conversion unit includes 3 flying capacitors and 8 pre-stage power switching transistors; the multi-inductor assembly includes 4 inductor elements; and the post-stage switched capacitor conversion unit includes 4 post-stage flying capacitors and 12 post-stage power switching transistors. The left ends of the four inductors are selectively connected to ground or the negative plate of the corresponding flying capacitor in the pre-stage series capacitor conversion unit via corresponding pre-stage power switches. The positive plates of the flying capacitors in the pre-stage series capacitor conversion unit are connected to each other via pre-stage power switches, and are selectively connected to the voltage input terminal and the left end of the final stage inductor via pre-stage power switches. The negative plate of the flying capacitor in the post-stage switched capacitor conversion unit is selectively connected to ground or the voltage output terminal via post-stage power switches. The positive plates of the flying capacitors in the post-stage switched capacitor conversion unit are electrically connected to the left ends of the corresponding inductors, and are electrically connected to the voltage output terminal via post-stage power switches.

[0016] Optionally, each inductor element in the multi-inductor assembly is evenly arranged along the voltage divider branch formed by the front-stage series capacitor conversion unit, and the inductance value of each inductor element is adapted to the voltage divider requirements of the front stage and the current adjustment requirements of the back stage.

[0017] The beneficial effects of this invention are as follows: In this embodiment of the invention, the input DC voltage is divided into stages by a front-stage series capacitor conversion unit, and multiple inductor components are electrically connected to different voltage division nodes to achieve energy coupling and transfer. At the same time, multiple conversion branches of the subsequent switched capacitor conversion unit are connected to the corresponding inductor components to jointly supply power to the output terminal, thereby forming a multi-path energy transfer structure. This is beneficial for distributing the output current path and reducing the degree of current concentration, thus improving the problem of limited output capability under high current power supply conditions during DC step-down. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of a scalable multi-inductor centered high conversion ratio and high power density DC-DC converter circuit provided in an embodiment of the present invention; Figure 2 This is an example of a schematic diagram of an N=3 scalable multi-inductor centered DC-DC converter circuit provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the working principle of the N=3 scalable multi-inductor centered DC-DC converter circuit provided in an embodiment of the present invention; Figure 4 This is a timing diagram of an N=3 scalable multi-inductor centered DC-DC converter circuit provided in an embodiment of the present invention; Figure 5 This is an example of a schematic diagram of an N=4 scalable multi-inductor centered DC-DC converter circuit provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the packaging provided by an embodiment of the present invention for a three-dimensional vertical power supply scenario. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0021] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products or devices.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] This invention aims to provide a DC-DC buck converter suitable for high-voltage input and ultra-low-voltage high-current output scenarios. Through a multi-voltage divider node and multi-inductor collaborative energy transfer structure, it achieves current sharing and energy distribution under high conversion ratio conditions, thereby improving the converter's energy transfer capability in high-current power supply scenarios and providing a circuit topology foundation for the subsequent realization of high-power-density power supply structures.

[0024] The core circuit architecture of the scalable multi-inductor central DC-DC converter proposed in this invention mainly includes: a voltage input terminal, a voltage output terminal, a front-stage series capacitor conversion unit, and a rear-stage switched capacitor conversion unit. The four components form a complete power conversion path through a preset electrical connection relationship. The multi-inductor component is located in the center of the circuit and plays a key role in energy transfer and current regulation.

[0025] In one embodiment of the present invention, the scalable multi-inductor centrally located DC-DC buck converter of the present invention includes a voltage input terminal, a front-stage series capacitor conversion unit, a multi-inductor assembly, a rear-stage switched capacitor conversion unit, and a voltage output terminal, which are connected in sequence. The voltage input terminal is used to connect to the input DC voltage; The front-stage series capacitor conversion unit includes multiple series capacitors and multiple front-stage power switching transistors electrically connected to the multiple series capacitors, and is used to perform series voltage division processing on the input DC voltage to form multiple voltage division nodes. The multi-inductor assembly is used to store energy between the front-stage series capacitor conversion unit and the rear-stage switched capacitor conversion unit to achieve energy coupling and maintain continuous current. The multi-inductor assembly includes multiple inductor elements, and the input terminal of each inductor element is electrically connected to the multiple voltage divider nodes respectively. The subsequent switched capacitor conversion unit includes multiple switched capacitor conversion branches, each of which is electrically connected to the output terminal of a corresponding inductor element. It is used to perform switched capacitor conversion on the voltage output by the inductor element and to supply power to the voltage output terminal. The voltage output terminal is used to output DC voltage to the load.

[0026] In this invention, the core function of the pre-stage series capacitor conversion unit is to reduce the equivalent voltage on the input side through the step-by-step series voltage division of the capacitors, thereby achieving high conversion ratio voltage preprocessing and laying the foundation for efficient energy conversion in the subsequent stage. From the perspective of circuit topology scalability, taking an N-stage (N is a positive integer greater than 1) structure as an example, the number of key components required by this pre-stage conversion unit follows the following rules: Number of capacitors: (N-1) capacitors are required in total. These capacitors are mainly connected in series, and step-by-step voltage division is achieved through reasonable switching control; Number of inductors: N inductors are required in total. Inductors are the core components for energy storage and transfer, and are distributed in each voltage division branch of the pre-stage circuit; Number of power transistors: 2N power transistors are required in total. The power transistors are fully controllable devices such as MOSFETs or IGBTs, used to realize the switching of the capacitor series state and the control of the inductor current. The specific electrical connection is as follows: the left end of each inductor switches between two working states through an independent power transistor, namely grounded or connected to the negative plate of the corresponding flying capacitor; at the same time, the positive plates of each flying capacitor are connected to each other through power transistors, and form electrical paths with the power input terminal and the left end of the final stage inductor respectively, ensuring stable energy transfer during voltage division.

[0027] In this invention, the core function of the post-stage switched capacitor conversion unit is to reduce the peak operating current and ripple of the inductor through the charging and discharging regulation of the flying capacitor, thereby achieving high-density, high-efficiency energy supply and ultimately outputting a stable DC voltage. Taking an N-stage (N is a positive integer greater than 1) structure as an example, the key components of this post-stage conversion unit are configured as follows: Number of capacitors: N capacitors are required. These capacitors are used as flying capacitors, mainly to reduce the DC component of the inductor current and to achieve temporary energy storage and transfer; Number of power transistors: 3N power transistors are required. The post-stage power transistors are adapted to lower voltage withstand requirements, so devices with better performance (such as lower on-resistance and faster switching speed) can be selected to improve the overall circuit efficiency. The specific electrical connections are as follows: the negative plate of the flying capacitor is connected to ground or the voltage output terminal through the power transistor to achieve switching of the discharge circuit; the positive plate of the flying capacitor is directly connected to the output inductor of the previous stage, and simultaneously forms a path with the voltage output terminal through the power transistor, ensuring that the energy stored in the flying capacitor can be efficiently transferred to the output terminal to meet the load requirements.

[0028] In this invention, the multi-inductor component comprises N inductors (N≥2), arranged between the front and rear stages, serving both as energy storage and current balancing and ripple suppression functions. This centrally located layout allows for high current output and module miniaturization while maintaining a high conversion ratio.

[0029] The advantages of the scalable multi-inductor centrally located DC-DC converter proposed in this invention are: Independent operation of the pre-amplifier and power amplifier stages: The pre-amplifier series capacitor conversion unit and the power amplifier switched capacitor conversion unit are electrically separated by a centrally located inductor component. Their operating frequencies and phases are not subject to any mandatory correlation or synchronization requirements. This feature significantly simplifies circuit design. In practical applications, parameters can be optimized separately for the pre-amplifier and power amplifier stages based on their performance requirements: Since the power amplifier stage has lower power transistor voltage requirements, devices with superior high-frequency characteristics can be selected to operate at higher frequencies, effectively reducing output voltage ripple and improving output stability and dynamic response performance; the pre-amplifier stage can operate within an appropriate frequency range, balancing power density and device losses while ensuring conversion efficiency and avoiding additional energy consumption at high frequencies.

[0030] Excellent Topology Scalability: Another core feature of this DC-DC converter is its flexible topology expansion capability. By simultaneously stacking the number of stages of the front-stage series capacitor conversion unit and the rear-stage switched capacitor conversion unit (i.e., synchronously increasing the N value), two key performance aspects can be optimized simultaneously: First, the stacked structure can significantly improve the output current capability of the circuit to meet the needs of high-load scenarios; second, increasing the number of stages can further reduce the equivalent voltage of the front-stage power transistors, reduce the conduction and switching losses of the power transistors, thereby improving the conversion efficiency of the entire converter.

[0031] In one embodiment of the present invention, the pre-stage series capacitor conversion unit adopts an N-stage topology, where N is a positive integer greater than 1; the pre-stage series capacitor conversion unit includes N-1 flying capacitors and 2N pre-stage power switching transistors; the multi-inductor assembly includes N inductor elements; The N-1 flying capacitors are connected in series between the voltage input terminal and ground; the input terminals of the N-1 inductors in the multi-inductor assembly are selectively connected to ground or the negative plate of the corresponding flying capacitor through the corresponding front-stage power switch, so as to realize the switching connection between different voltage divider nodes and the input terminals of the inductors; the input terminal of the Nth inductor is selectively connected to ground or electrically connected to the end node of the series chain of the N-1 flying capacitors through the front-stage power switch. The positive plates of the N-1 flying capacitors are interconnected through a front-stage power switch, and the positive plates of the N-1 flying capacitors selectively form an electrical path with the voltage input terminal and selectively form an electrical path with the input terminal of the Nth inductor through the front-stage power switch.

[0032] In one embodiment of the present invention, such as Figure 1 and Figure 2 As shown, the pre-stage series capacitor conversion unit is used to perform hierarchical processing of the input-side DC voltage and form multiple voltage divider nodes to provide distributed input voltage to the multi-inductor component. This pre-stage series capacitor conversion unit adopts an N-stage topology, where N is a positive integer greater than 1. The pre-stage series capacitor conversion unit and the multi-inductor component work together to form a multi-path energy input structure.

[0033] Specifically, the pre-stage series capacitor conversion unit includes N-1 flying capacitors and 2N pre-stage power switching transistors, and the multi-inductor assembly includes N inductor elements. The N-1 flying capacitors are connected in series between the voltage input terminal and ground, forming multiple switchable voltage divider nodes under the control of the pre-stage power switching transistors. The input terminals of each inductor element in the multi-inductor assembly are connected to the corresponding voltage divider node, thereby distributing the input voltage to multiple inductor branches and achieving energy distribution.

[0034] During operation, the front-stage power switch changes the connection state of each voltage divider node, allowing the input terminals of each inductor to switch between grounded and connected to the corresponding negative plate of the flying capacitor, thus achieving selective access to different voltage divider potentials. Simultaneously, the positive plates of each flying capacitor form a controllable connection through the front-stage power switch, and under the action of a control signal, can selectively form an electrical path with either the voltage input terminal or the input terminal of the final-stage inductor, thereby completing the charging and discharging process of the flying capacitor and the switching of the series voltage divider state.

[0035] It should be noted that in an N-stage topology, N-1 flying capacitors are sufficient to form N voltage divider nodes. This is because flying capacitors are used to establish the potential difference between adjacent voltage divider stages; only one flying capacitor is needed between any two adjacent voltage divider stages to achieve potential separation. When the number of voltage divider stages is N, only N-1 flying capacitors are needed to form a complete voltage divider link between the voltage input terminal and ground. The path at the end of the voltage divider link uses ground as a reference potential, thus eliminating the need for additional flying capacitors to establish the final stage voltage divider.

[0036] The Nth-stage branch is designed to provide a stable end-point reference path for the series voltage divider chain and ensure that the chain forms a closed energy path under different operating conditions. The input of this Nth inductor is selectively grounded via the preceding power switch or connected to the end node of the flying capacitor series chain. This allows the final-stage branch to participate in energy transfer and stabilize the potential of each voltage divider node under different switching conditions, preventing the voltage divider network from being in a floating state and thus improving the stability and controllability of the circuit operation.

[0037] In this invention, the flying capacitor is used for energy storage and transfer under different switching phases, and participates in the graded voltage division of the input voltage through a series connection. The voltage division node refers to the potential node formed by the series connection of the flying capacitor and the switching of the preceding power switch, used to provide input voltage to the corresponding inductor. The terminal node is the end of the flying capacitor series chain closest to the ground reference, used to complete the voltage division link closure and provide a reference potential for the final inductor branch. Through this structural arrangement, while maintaining the energy transfer mode with the inductor in the center, graded processing of the input voltage can be achieved, providing stable multi-channel input conditions for the subsequent switched-capacitor conversion unit.

[0038] In one embodiment of the present invention, the front-stage power switch is a MOSFET or an IGBT. The front-stage series capacitor switching unit is located in the high-voltage region of the input side. Its power switch needs to withstand high voltage stress and complete the switching of the flying capacitor series state and the connection control of the voltage divider node. Therefore, it has high requirements for the voltage withstand capability and reliability of the device. MOSFET devices have the characteristics of fast switching speed, low drive power, and low conduction loss, making them suitable for medium- and high-frequency operating scenarios. IGBT devices, on the other hand, have high voltage withstand capability and strong current carrying capacity, making them suitable for applications with high input voltage or high power levels.

[0039] In practical applications, the appropriate type of power device can be selected based on the input voltage level, operating frequency, and power density requirements. For example, when the input voltage is high and the switching frequency is relatively low, IGBT devices are preferred to improve the voltage withstand margin. When it is necessary to increase the switching frequency, reduce switching losses, or improve system efficiency, MOSFET devices are preferred. This invention does not limit the specific device type of the front-end power switch; as long as it can achieve the corresponding switching control function, it falls within the protection scope of this invention.

[0040] In one embodiment of the present invention, the subsequent switched capacitor conversion unit adopts an N-stage topology; the subsequent switched capacitor conversion unit includes N flying capacitors and 3N subsequent power switching transistors, and forms N switched capacitor conversion branches; The positive plates of the N flying capacitors are electrically connected to the output terminals of the corresponding inductors in the multi-inductor assembly; the negative plates of the N flying capacitors are selectively connected to ground or the voltage output terminal through the corresponding power switching transistors; the positive plates of the N flying capacitors also form an electrical path with the voltage output terminal through the corresponding power switching transistors, so as to realize switched capacitor energy transfer of the output voltage through the charging and discharging of the flying capacitors.

[0041] In one embodiment of the present invention, such as Figure 2 As shown, the subsequent switched-capacitor conversion unit is located after the multi-inductor assembly. It is used to regulate the inductor output energy using a switched-capacitor method and transfer energy to the voltage output terminal. Taking N=3 as an example, the multi-inductor assembly includes inductors L1, L2, and L3. Correspondingly, the subsequent switched-capacitor conversion unit includes three switched-capacitor conversion branches, each branch consisting of a flying capacitor C. F1 It consists of the corresponding power switching transistors and the corresponding switching nodes V. SW1 V SW2 V SW3 .

[0042] Specifically, the output terminals of inductors L1, L2, and L3 are directly electrically connected to the positive plate of the flying capacitor CF1, allowing the energy released by each inductor to enter the corresponding switched capacitor switching branch. When the corresponding switching node V... SW1 V SW2 V SW3 When the power switching transistors at the downstream stage are turned on and off according to a predetermined timing sequence, each flying capacitor switches between different electrical connection states, thereby completing the charging and discharging process.

[0043] During the charging phase of the flying capacitor, C F1The positive plate is connected to the preceding stage energy path through inductor L1, and the negative plate forms a loop with ground through the corresponding subsequent stage power switch, allowing the inductor current to charge the flying capacitor; during the discharge phase, by switching the conduction state of the subsequent stage power switch, C F1 The negative plate is switched to the voltage output terminal, while its positive plate forms a conductive path with the output side via the corresponding switching path, thereby releasing the energy stored in the flying capacitor to the load side. The other two branches operate in the same way as described above, only corresponding to different switching nodes V. SW2 With V SW3 .

[0044] In this way, each flying capacitor alternately performs energy storage and release in adjacent operating phases, realizing a typical switched capacitor energy transport mechanism. Since multiple switched capacitor switching branches work corresponding to different inductor channels, the energy from L1, L2, and L3 is shunt and superimposed on the output side, thereby reducing the current stress of a single branch and helping to reduce output voltage ripple and improve output stability.

[0045] Furthermore, since the subsequent switched capacitor conversion unit is located on the low-voltage side after the series voltage divider of the preceding stage, the voltage stress on each subsequent power switch is relatively low. Therefore, devices with lower on-resistance and faster switching speed can be used to further reduce conduction losses and improve overall conversion efficiency. When the number of stages N increases, only the corresponding number of inductors, flying capacitors, and switching node structures need to be added to maintain the same working mechanism and achieve output capability expansion.

[0046] like Figure 2 As shown, the pre-stage series capacitor conversion unit is used to perform step-by-step voltage division and preprocessing of the input voltage. Preferably, taking an N-stage structure as an example, this unit includes (N-1) series capacitors, N inductors, and 2N power transistors. The power transistors are preferably fully controllable devices such as MOSFETs or IGBTs.

[0047] Furthermore, the first terminal of each inductor can be selectively grounded or connected to the negative plate of the corresponding flying capacitor via an independent power transistor, forming two operating states. The positive plates of each flying capacitor are interconnected via power transistors, forming electrical paths with the power input terminal and the first terminal of the final stage inductor, respectively, to achieve stable energy transfer during voltage division. This structure reduces the withstand voltage requirement of individual power devices while ensuring a high conversion ratio. The subsequent switched capacitor conversion unit reduces the peak inductor operating current and ripple through the charging and discharging regulation of the flying capacitors, outputting a stable DC voltage. Preferably, taking an N-stage structure as an example, this unit includes N flying capacitors and 3N power transistors. Since the withstand voltage of the subsequent stage power transistors is relatively low, devices with lower on-resistance and faster switching speeds can be selected to improve efficiency. Furthermore, the negative plate of the flying capacitor can be selectively grounded or connected to the voltage output terminal via a power transistor, realizing the switching of the discharge circuit; the positive plate of the flying capacitor is directly connected to the output inductor of the previous stage, and forms a path with the voltage output terminal through a power transistor, ensuring that the energy stored in the flying capacitor is efficiently transferred to the output terminal to meet the load requirements.

[0048] Optionally, taking N=3 as an example, the operating timing and main current flow of this structure, and the voltage waveforms of the main operating nodes are as follows: Figure 3 and Figure 4 As shown. Taking inductor L3 as an example, its left side can be connected to ground via switch S2 or to the power supply via switch S1. Corresponding to this V... LL3 The node is low or high (V) IN / 3 For inductor L2, its left side can be connected to ground via S4 or to a high level via switches S2 and S3. The voltage rating of the flying capacitor is consistent with that of a traditional series capacitor step-down circuit. The right-side switched capacitor circuit operates in two different phases: in phase one, the inductor current flows to the output through the flying capacitor and switch S8; or the flying capacitor current and the inductor current are connected in parallel and supply power to the output through switch S7. The node on the right side of the inductor switches between one and two times the output voltage. Its duty cycle remains at 50%, and there is no explicit phase frequency requirement with the preceding circuit.

[0049] Alternatively, taking N=4 as an example, its circuit structure is as follows: Figure 5 As shown, its working principle is consistent with the above structure. The front stage further reduces the voltage of the switching node by stacking switched capacitor units, thereby improving the conversion performance while meeting the requirement of larger output current.

[0050] In one embodiment of the present invention, the withstand voltage rating of the subsequent power switch is lower than that of the preceding power switch, the on-resistance of the subsequent power switch is less than that of the preceding power switch, and the switching speed of the subsequent power switch is greater than that of the preceding power switch.

[0051] In one embodiment of the present invention, the subsequent switched capacitor conversion unit is located on the low-voltage side after the voltage division of the preceding series capacitor. The turn-off voltage of the corresponding subsequent power switch is mainly determined by the voltage across the subsequent flying capacitor and the output voltage, and the voltage stress is significantly lower than that of the preceding power switch in the preceding series capacitor conversion unit. In contrast, the preceding power switch needs to participate in the voltage division and reconstruction process of the high voltage on the input side, and its turn-off voltage is usually directly related to the input voltage or the voltage of the voltage divider link node, thus requiring higher withstand voltage design. Based on this difference in voltage stress distribution, the preceding power switch is selected as a high-voltage withstand device, while the subsequent power switch is selected as a low-voltage withstand device, in order to achieve a match between device selection and circuit stress.

[0052] Regarding the loss mechanism of devices, the main losses of power switches include conduction losses and switching losses. Conduction losses are generally related to on-resistance and current, while switching losses are generally related to switching transition time, switching frequency, and the overlap of instantaneous voltage and current during switching. Since the downstream switched-capacitor conversion unit is responsible for directly supplying power to the load side, and its branch current is closely related to the output current, the current stress of the downstream power switch is relatively more prominent during the conduction phase. At the same time, in order to reduce output ripple and improve output dynamic response, the downstream stage is often configured to operate at a higher switching frequency, making switching losses more sensitive in the downstream stage. Therefore, in this embodiment of the invention, a low-voltage power device with lower on-resistance and faster switching speed is preferred as the downstream power switch to reduce conduction losses and suppress high-frequency switching losses, thereby improving the energy transfer efficiency of the downstream stage.

[0053] In contrast, the pre-stage series capacitor conversion unit is mainly used for series voltage division and node switching of high-voltage input. Its power switching transistors face higher voltage stress, and the selection of components prioritizes meeting the requirements of voltage withstand margin and safety and reliability. Under the same process conditions, high-voltage components usually have larger on-resistance, larger parasitic capacitance, and relatively slower switching speed. This embodiment of the invention concentrates the high voltage withstand requirement in the pre-stage and the low voltage withstand, high speed, and low resistance requirement in the post-stage, so that the characteristics of the components match the functional positioning of each stage, avoiding unnecessary losses and area overhead caused by uniformly using high voltage withstand components throughout the entire circuit.

[0054] In one specific embodiment, taking a high DC bus voltage at the input side and a low-voltage, high-current power supply at the output side as an example, the front-stage power switching transistors can be MOSFETs or IGBTs with higher voltage ratings to meet the turn-off voltage requirements of the input-side voltage divider link; the rear-stage power switching transistors can be MOSFETs or gallium nitrides with lower voltage ratings but lower on-resistance and faster switching speeds to meet the low-voltage, high-frequency operation requirements of the rear-stage. Through this hierarchical device configuration, while meeting voltage stress and reliability requirements, the conduction and switching losses of the rear-stage can be reduced, heat generation can be decreased, and overall conversion efficiency can be improved. Furthermore, it is beneficial to increase the output capacity per unit volume under the same heat dissipation conditions, thereby supporting high-power-density applications.

[0055] In one embodiment of the present invention, the pre-stage series capacitor conversion unit and the post-stage switched capacitor conversion unit operate at independent switching control frequencies, and the switching operating frequency of the post-stage switched capacitor conversion unit is higher than the switching operating frequency of the pre-stage series capacitor conversion unit.

[0056] In one embodiment of the present invention, the front-stage series capacitor conversion unit and the rear-stage switched capacitor conversion unit adopt independent switching control methods in terms of control strategy. That is, the two stages of circuit are controlled by their respective drive control signals, and their switching frequencies do not need to maintain a fixed ratio or be synchronously locked. Since energy transfer and current coupling are achieved between the front-stage and rear-stage through multi-inductor components, and the inductor itself has energy buffering and current continuity characteristics, the operating states of the two stages can be effectively decoupled electrically, allowing the front-stage and rear-stage to independently optimize their operating frequencies according to their respective functional requirements.

[0057] Specifically, the pre-stage series capacitor conversion unit mainly undertakes the functions of series voltage division and energy preprocessing of the input side voltage. During its operation, the power switching transistors are subjected to high voltage stress. If the frequency is too high, it will significantly increase switching losses and aggravate the thermal stress of the devices. Therefore, in this embodiment of the invention, the pre-stage preferably operates in a relatively low or medium switching frequency range to achieve a balance between conversion efficiency, device losses, and reliability.

[0058] The subsequent switched-capacitor conversion unit is located on the low-voltage side and is mainly used for efficient energy transfer and output regulation. Its power switching transistors have lower voltage requirements, making high-speed switching devices suitable. Setting the switching frequency of the subsequent stage higher than that of the preceding stage helps shorten the charge-discharge cycle of the flying capacitor, improves the continuity of energy transfer, thereby reducing output voltage ripple and improving dynamic response performance under sudden load changes. Simultaneously, high-frequency operation reduces output filtering requirements, allowing for a smaller output-side energy storage element size.

[0059] By employing the aforementioned collaborative operation of different frequencies between the preceding and following stages, this invention achieves a balance between optimizing high-voltage side efficiency and optimizing low-voltage side dynamic performance without increasing control complexity. This enables the converter to achieve stable operation and superior overall performance in high conversion ratio and high current output application scenarios.

[0060] In one embodiment of the present invention, both the pre-stage series capacitor conversion unit and the post-stage switched capacitor conversion unit are cascadeable expansion structures, and the number of inductors in the multi-inductor assembly corresponds to the number of stages of the pre-stage series capacitor conversion unit and the post-stage switched capacitor conversion unit.

[0061] In one embodiment of the present invention, both the pre-stage series capacitor conversion unit and the post-stage switched capacitor conversion unit adopt a cascaded and expandable topology. That is, by increasing the number of stages, the performance parameters can be linearly expanded while maintaining the consistency of the basic circuit structure. Specifically, as the number of stages in the pre-stage series capacitor conversion unit increases, the number of flying capacitors participating in voltage division in its series voltage divider network increases accordingly, thereby forming more voltage divider nodes. This allows the input voltage to be distributed across multiple paths, reducing the voltage stress on individual power devices. Simultaneously, the number of stages in the post-stage switched capacitor conversion unit increases synchronously to maintain the energy transfer path matching the pre-stage output structure.

[0062] Corresponding to the cascaded structure described above, the number of inductors in the multi-inductor assembly is set one-to-one with the number of stages in the preceding and following stages. Each inductor is connected between its corresponding voltage divider node and the subsequent switched-capacitor conversion branch, allowing the energy after voltage division on the input side to be transferred to the output side via multiple paths, achieving current shunting and superposition. As the number of stages increases, the current is distributed across multiple inductor branches, helping to reduce the current stress on a single path and maintain the continuity of energy transmission. Through this cascaded expansion method, the present invention can scale up the converter design according to different load requirements without changing the basic working principle, ensuring that the circuit maintains consistent topological characteristics and operating mechanisms at different power levels, thereby improving the flexibility and adaptability of the structural design.

[0063] In one embodiment of the present invention, each inductor element in the multi-inductor assembly is uniformly arranged along the voltage divider branch formed by the front-stage series capacitor conversion unit, and the inductance value of each inductor element is adapted and set according to the voltage divider requirements of the front stage and the current adjustment requirements of the back stage.

[0064] In one embodiment of the present invention, the inductors in the multi-inductor assembly are uniformly arranged along multiple voltage divider branches formed by the preceding series capacitor conversion unit, so that each voltage divider node corresponds to an energy transfer path. Through this uniform distribution, the electrical energy after series voltage division on the input side can enter different inductor branches respectively, realizing the current sharing and transmission in multiple paths, thereby reducing the current stress on individual inductors and corresponding power devices, and helping to maintain the consistency of the operating state of each branch.

[0065] The inductance values ​​of each inductor are not fixed but are selected to match the voltage division ratio of the preceding stage and the current regulation requirements of the subsequent switched capacitor conversion unit. Specifically, the voltage division ratio of the preceding stage determines the voltage level of each voltage division node, while the requirements for current ripple and dynamic response during energy transfer in the subsequent stage constrain the energy storage capacity of the inductors. Therefore, by uniformly designing or proportionally optimizing the inductance values ​​of different branches, each branch can achieve a similar rate of current change during energy transfer, thereby reducing current imbalance between branches and improving overall output stability.

[0066] Through the above-mentioned uniform inductor arrangement and parameter matching method, the multi-inductor component can achieve the synergistic effect of current regulation and ripple suppression while ensuring continuous energy transfer, providing stable input conditions for the subsequent switched capacitor conversion unit.

[0067] In one embodiment of the present invention, when N=3, the front-stage series capacitor conversion unit includes 2 flying capacitors and 6 front-stage power switching transistors; the multi-inductor assembly includes 3 inductor elements; the rear-stage switched capacitor conversion unit includes 3 rear-stage flying capacitors and 9 rear-stage power switching transistors. Specifically, the left ends of the three inductors are selectively connected to ground or the negative plate of the corresponding flying capacitor in the pre-stage series capacitor conversion unit via corresponding pre-stage power switches; the positive plates of the flying capacitors in the pre-stage series capacitor conversion unit are connected to each other via pre-stage power switches, and are selectively connected to the voltage input terminal and the left end of the final stage inductor via pre-stage power switches; the negative plate of the flying capacitor in the post-stage switched capacitor conversion unit is selectively connected to ground or the voltage output terminal via post-stage power switches; the positive plate of the flying capacitor in the post-stage switched capacitor conversion unit is electrically connected to the left end of the corresponding inductor, and is electrically connected to the voltage output terminal via post-stage power switches.

[0068] In one embodiment of the present invention, when N=4, the pre-stage series capacitor conversion unit includes 3 flying capacitors and 8 pre-stage power switching transistors; the multi-inductor assembly includes 4 inductor elements; the post-stage switched capacitor conversion unit includes 4 post-stage flying capacitors and 12 post-stage power switching transistors. The left ends of the four inductors are selectively connected to ground or the negative plate of the corresponding flying capacitor in the pre-stage series capacitor conversion unit via corresponding pre-stage power switches. The positive plates of the flying capacitors in the pre-stage series capacitor conversion unit are connected to each other via pre-stage power switches, and are selectively connected to the voltage input terminal and the left end of the final stage inductor via pre-stage power switches. The negative plate of the flying capacitor in the post-stage switched capacitor conversion unit is selectively connected to ground or the voltage output terminal via post-stage power switches. The positive plates of the flying capacitors in the post-stage switched capacitor conversion unit are electrically connected to the left ends of the corresponding inductors, and are electrically connected to the voltage output terminal via post-stage power switches.

[0069] like Figure 6 As shown, preferably, the present invention can package the aforementioned modular power units and inductors in a three-dimensional vertical stacking manner to form a high-density power module. This module can be placed directly close to the load chip, shortening the power supply path, reducing transmission loss and improving power supply efficiency, thus meeting the application requirements of the three-dimensional vertical power supply system for miniaturization and high performance of power converters.

[0070] In summary, the scalable multi-inductor centrally located high conversion ratio and high power density DC-DC converter provided by this invention, through modular design, independent optimization of front and rear stages, centrally located multi-inductor architecture and three-dimensional packaging, can achieve high voltage input, high current output and high power density in a limited space. It is particularly suitable for high-current, low-voltage power supply scenarios such as high-performance computing, data centers, and artificial intelligence chips.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A scalable multi-inductor centered DC buck converter, characterized in that, It includes, in sequence, a voltage input terminal, a pre-stage series capacitor conversion unit, a multi-inductor assembly, a post-stage switched capacitor conversion unit, and a voltage output terminal: The voltage input terminal is used to connect to the input DC voltage; The front-stage series capacitor conversion unit includes multiple series capacitors and multiple front-stage power switching transistors electrically connected to the multiple series capacitors, and is used to perform series voltage division processing on the input DC voltage to form multiple voltage division nodes. The multi-inductor assembly is used to store energy between the front-stage series capacitor conversion unit and the rear-stage switched capacitor conversion unit to achieve energy coupling and maintain continuous current. The multi-inductor assembly includes multiple inductor elements, and the input terminal of each inductor element is electrically connected to the multiple voltage divider nodes respectively. The subsequent switched capacitor conversion unit includes multiple switched capacitor conversion branches, each of which is electrically connected to the output terminal of a corresponding inductor element. It is used to perform switched capacitor conversion on the voltage output by the inductor element and to supply power to the voltage output terminal. The voltage output terminal is used to output DC voltage to the load.

2. The scalable multi-inductance centered DC buck converter of claim 1, wherein, The pre-stage series capacitor conversion unit adopts an N-stage topology, where N is a positive integer greater than 1; the pre-stage series capacitor conversion unit includes N-1 flying capacitors and 2N pre-stage power switching transistors; the multi-inductor assembly includes N inductor elements; The N-1 flying capacitors are connected in series between the voltage input terminal and ground; the input terminals of the N-1 inductors in the multi-inductor assembly are selectively connected to ground or the negative plate of the corresponding flying capacitor through the corresponding front-stage power switch, so as to realize the switching connection between different voltage divider nodes and the input terminals of the inductors; the input terminal of the Nth inductor is selectively connected to ground or electrically connected to the end node of the series chain of the N-1 flying capacitors through the front-stage power switch. The positive plates of the N-1 flying capacitors are interconnected through a front-stage power switch, and the positive plates of the N-1 flying capacitors selectively form an electrical path with the voltage input terminal and selectively form an electrical path with the input terminal of the Nth inductor through the front-stage power switch.

3. The scalable multi-inductance centered DC buck converter of claim 1 or 2, wherein, The front-end power switch uses either a MOSFET or an IGBT.

4. The scalable multi-inductance centered DC buck converter of claim 2, wherein, The subsequent switched capacitor conversion unit adopts an N-stage topology; the subsequent switched capacitor conversion unit includes N flying capacitors and 3N subsequent power switching transistors, forming N switched capacitor conversion branches; The positive plates of the N flying capacitors are electrically connected to the output terminals of the corresponding inductors in the multi-inductor assembly; the negative plates of the N flying capacitors are selectively connected to ground or the voltage output terminal through the corresponding power switching transistors; the positive plates of the N flying capacitors also form an electrical path with the voltage output terminal through the corresponding power switching transistors, so as to realize switched capacitor energy transfer of the output voltage through the charging and discharging of the flying capacitors.

5. The scalable multi-inductance centered DC buck converter of claim 4, wherein, The voltage rating of the subsequent power switch is lower than that of the preceding power switch, the on-resistance of the subsequent power switch is less than that of the preceding power switch, and the switching speed of the subsequent power switch is greater than that of the preceding power switch.

6. The scalable multi-inductance centered DC buck converter of claim 1, wherein, The pre-stage series capacitor conversion unit and the post-stage switched capacitor conversion unit operate at independent switching control frequencies, and the switching operating frequency of the post-stage switched capacitor conversion unit is higher than that of the pre-stage series capacitor conversion unit.

7. The scalable multi-inductance centered DC buck converter of claim 4, wherein, Both the pre-stage series capacitor conversion unit and the post-stage switched capacitor conversion unit are cascaded and expandable structures, and the number of inductors in the multi-inductor assembly corresponds to the number of stages of the pre-stage series capacitor conversion unit and the post-stage switched capacitor conversion unit.

8. The scalable multi-inductance centered DC buck converter of claim 7, wherein, When N=3, the pre-stage series capacitor conversion unit includes 2 flying capacitors and 6 pre-stage power switching transistors; the multi-inductor assembly includes 3 inductor elements; the post-stage switched capacitor conversion unit includes 3 post-stage flying capacitors and 9 post-stage power switching transistors. Specifically, the left ends of the three inductors are selectively connected to ground or the negative plate of the corresponding flying capacitor in the pre-stage series capacitor conversion unit via corresponding pre-stage power switches; the positive plates of the flying capacitors in the pre-stage series capacitor conversion unit are connected to each other via pre-stage power switches, and are selectively connected to the voltage input terminal and the left end of the final stage inductor via pre-stage power switches; the negative plate of the flying capacitor in the post-stage switched capacitor conversion unit is selectively connected to ground or the voltage output terminal via post-stage power switches; the positive plate of the flying capacitor in the post-stage switched capacitor conversion unit is electrically connected to the left end of the corresponding inductor, and is electrically connected to the voltage output terminal via post-stage power switches.

9. The scalable multi-inductance centered DC buck converter of claim 7, wherein, When N=4, the pre-stage series capacitor conversion unit includes 3 flying capacitors and 8 pre-stage power switching transistors; the multi-inductor assembly includes 4 inductor elements; the post-stage switched capacitor conversion unit includes 4 post-stage flying capacitors and 12 post-stage power switching transistors. The left ends of the four inductors are selectively connected to ground or the negative plate of the corresponding flying capacitor in the pre-stage series capacitor conversion unit via corresponding pre-stage power switches. The positive plates of the flying capacitors in the pre-stage series capacitor conversion unit are connected to each other via pre-stage power switches, and are selectively connected to the voltage input terminal and the left end of the final stage inductor via pre-stage power switches. The negative plate of the flying capacitor in the post-stage switched capacitor conversion unit is selectively connected to ground or the voltage output terminal via post-stage power switches. The positive plates of the flying capacitors in the post-stage switched capacitor conversion unit are electrically connected to the left ends of the corresponding inductors, and are electrically connected to the voltage output terminal via post-stage power switches.

10. The scalable multi-inductance centered DC buck converter of claim 1, wherein, Each inductor in the multi-inductor assembly is evenly arranged along the voltage divider branch formed by the front-stage series capacitor conversion unit, and the inductance value of each inductor is adapted to the voltage divider requirements of the front stage and the current adjustment requirements of the back stage.

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