A non-isolated hybrid switched capacitor converter of cascaded switched capacitor cells

Abstract

The application belongs to the technical field of power electronics, and relates to a non-isolated hybrid switched capacitor converter of cascaded switched capacitor units, which comprises a flying capacitor, a switching tube, a synchronous rectification tube, a coupling inductor, an input and output end, a filter capacitor and a load. n+1,1 , n+1,2 , a flying capacitor C n,1 , C n,2 is composed of a switching tube Q n+1,1 , Q n+1,2 , a flying capacitor C n,1 , C n,2 . The step-down ratio of each cascaded unit is doubled, and the device stress is reduced. The switched capacitor network first realizes 2n:1 step-down, cooperates with the coupling inductor and the synchronous rectification circuit to form a hybrid topology, and the overall conversion ratio reaches 2n+2:1. The excitation energy of the coupling inductor is relied on to realize zero-voltage turn-on of all switching tubes, and the switching loss is reduced. The application does not need large magnetic elements, has the advantages of high efficiency, high power density, high step-down conversion ratio and flexible expansion, and is suitable for data center low-voltage large-current conversion scenes.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology, specifically relating to a non-isolated hybrid switched capacitor converter with cascaded switched capacitor units. Background Technology

[0002] With the rapid development of the big data and cloud computing industries, the demand for computing power in data centers continues to surge. The 48V bus power supply architecture, with its strong adaptability and high power supply stability, has become the mainstream power supply architecture for data centers. In this architecture, the intermediate bus converter, as the core power conversion unit, needs to efficiently step down the 48V input voltage to the low-voltage intermediate bus voltage. Its performance directly determines the power density and conversion efficiency of the entire power supply system, and is key to improving the overall performance of the data center power supply system.

[0003] Currently, mainstream buck converter solutions applied to this scenario all have technical shortcomings, making it difficult to simultaneously achieve various core performance indicators. Among them, while isolation transformer converters can achieve high step-down ratios, the bulky size and complex structural design of the supporting magnetic components significantly limit the improvement of system power density; pure switched capacitor converters have a simple structure and high integration, but suffer from high conduction losses, poor high turns ratio adaptability, and high component costs; traditional multiphase Buck converters have limited step-down operating ranges and cannot meet the requirements of large-scale step-down conditions from 48V to low voltage.

[0004] In summary, existing buck converter technologies generally have shortcomings and cannot simultaneously meet the core application requirements of high buck ratio, high power density, and high efficiency, which greatly restricts the performance upgrade of data center 48V power supply systems. Therefore, it is urgent to develop a new type of converter to solve the above-mentioned technical pain points. Summary of the Invention

[0005] This invention provides the following technical solution: a non-isolated hybrid switched capacitor converter with cascaded switched capacitor units, comprising: a flying capacitor C 1,1 ~C n,2 Switching transistor Q 1,1 ~Q n+1,2 SR switching transistor a SR b Coupled inductors L1 and L2, input voltage source V in Output terminal V o Grounding terminal, filter capacitor C o and load R o The coupled inductors L1 and L2 are coupled to each other; n is an integer greater than or equal to 1.

[0006] The converter's circuit connection method is as follows: switching transistor Q 1,1 One end is connected to the input voltage source V in Positive electrode, switching transistor Q1,1 The other end is connected in series with the switching transistor Q. 2,1 Q 3,1 , …… Q n+1,1 The same terminal of the coupling inductor L1 is connected afterward; the switching transistor Q 1,2 One end is connected to the input voltage source V in Positive electrode, switching transistor Q 1,2 The other end is connected in series with the switching transistor Q. 2,2 Q 3,2 , …… Q n+1,2 Connect the opposite-named terminal of the coupling inductor L2, and connect the same-named terminal of the coupling inductor L2 to the opposite-named terminal of the coupling inductor L1.

[0007] Flying capacitor C 1,1 The two ends are respectively connected to the switching transistor Q. 1,1 Q 2,1 Connection node and switching transistor Q 2,2 Q 3,2 The connection node, the flying capacitor C 1,2 The two ends are respectively connected to the switching transistor Q. 2,1 Q 3,1 Connection node and switching transistor Q 1,2 Q 2,2 Connection node; Flying capacitor C 2,1 The two ends are respectively connected to the switching transistor Q. 2,1 Q 3,1 Connection node and switching transistor Q 3,2 Q 4,2 The connection node, the flying capacitor C 2,2 The two ends are respectively connected to the switching transistor Q. 3,1 Q 4,1 Connection node and switching transistor Q 2,2 Q 3,2 The connection nodes are cascaded sequentially according to the above cross-connection rules, until the flying capacitor C is reached. n-1,1 The two ends are respectively connected to the switching transistor Q. n-1,1 Q n,1 Connection node and switching transistor Q n,2 Q n+1,2 The connection node, the flying capacitor C n-1,2 The two ends are respectively connected to the switching transistor Q. n,1 Q n+1,1 Connection node and switching transistor Q n-1,2 Q n,2 Connection node; Flying capacitor C n,1 The two ends are respectively connected to the switching transistor Q. n,1 Q n+1,1 Connection node and switching transistor Q n+1,2 The connection node of the coupled inductor L2, and the flying capacitor Cn,2 The two ends are respectively connected to the switching transistor Q. n+1,1 The connection node of the coupling inductor L1 and the switching transistor Q n,2 Q n+1,2 The connection node.

[0008] Filter capacitor C o With load R o After parallel connection, one end is grounded and the other end is connected to the connection node of coupling inductors L1 and L2; filter capacitor C o One end is grounded, and the other end is connected to the output terminal V. o ; Switching transistor SR a One end is grounded and the other end is connected to the switching transistor Q. n+1,1 Connection node of coupling inductor L1; switching transistor SR b One end is grounded and the other end is connected to the switching transistor Q. n+1,2 The connection node of the coupled inductor L2.

[0009] Preferably, in the converter, a single switched capacitor unit includes a switching transistor Q. n+1,1 Q n+1,2 With flying capacitor C n,1 C n,2 ; Switching transistor Q n+1,1 One end is connected to the flying capacitor C n,1 At one end, the flying capacitor C n,1 The other end is connected to the switching transistor Q. n+1,2 At one end, the switching transistor Q n+1,2 The other end is connected to the flying capacitor C. n,2 At one end, the flying capacitor C n,2 The other end is connected to the switching transistor Q. n+1,1 On the other end, each cascaded switched capacitor unit increases the converter's step-down ratio by 2 times.

[0010] Preferably, when n is an even number; the switching transistor Q 1,1 Q 2,2 Q 3,1 Q n,2 Q n+1,1 SR switching transistor b Common drive waveform Φ A ; Switching transistor Q 1,2 Q 2,1 Q 3,2 Q n,1 Q n+1,2 SR switching transistor a Common drive waveform Φ B ; driving waveform Φ A With driving waveform Φ B They are complementary, with a duty cycle of 50% for both, and a dead time is set between the two sets of drive waveforms.

[0011] More preferably, during the dead time, the excitation current I of the coupled inductor is relied upon. Lm Complete the soft-charge and discharge of the output capacitors of all switching transistors to achieve zero-voltage turn-on of all switching transistors; ignoring leakage inductance, the soft-switching conditions are as follows: (5) It can be simplified into a calculation formula: (6) In the formula, L m C is the magnetizing inductance value. Q(i,1) C Q(i,2) C SRa C SRb These are the output capacitors for the corresponding switching transistors; U Q(i,1) U Q(i,2) U SRa U SRb This is the voltage difference required for the output capacitor of the corresponding switching transistor to fully charge and discharge.

[0012] Preferably, the voltage gain of the converter satisfies: (1) In the formula, n is the number of cascaded switched capacitor units.

[0013] Preferably, the converter circuit operates symmetrically on both sides; all flying capacitors C 1,1 ~C n,2 The steady-state voltages are equal, satisfying: (2) Flying capacitor C n,1 With C n,2 The effective values ​​of the corresponding branch currents are equal, but the phase difference is 180°.

[0014] Preferably, all flying capacitors of the converter have a capacitance value of C. F ; driving waveform Φ A The equivalent capacitance C of the flying capacitor network at high level eq1 , driving waveform Φ B Equivalent capacitance C at high level eq2 satisfy: (3) (4) In the formula, n is the number of cascaded switched capacitor units.

[0015] Preferably, the converter's coupling inductance and leakage inductance are evenly distributed, L k1 =L k2 =L r / 2, the resonant frequency of the converter satisfies: (9) In the formula, L r For the total equivalent leakage inductance, C F This refers to the capacitance value of a single flying capacitor.

[0016] Preferably, the converter is used for intermediate voltage transformation in a two-stage power supply architecture for a 48V bus in a data center, and the step-down ratio can be flexibly adjusted by increasing or decreasing the number of cascaded switching capacitor units.

[0017] The beneficial effects of this invention are: 1. This invention enables soft-switching operation of all main power switching transistors, effectively eliminating switching losses caused by hard switching of the switching transistors; at the same time, the converter mainly relies on the switched capacitor network to undertake the voltage reduction function, the pressure on magnetic components to participate in power conversion is greatly reduced, the overall magnetic loss is significantly reduced, effectively improving the overall power conversion efficiency of the converter and meeting the requirements of high-efficiency operation.

[0018] 2. This invention adopts a topology structure in which a front-end switched capacitor network undertakes the main voltage reduction task, which greatly reduces the dependence on large-volume magnetic components. The subsequent magnetic components can be miniaturized, effectively reducing the overall size of the converter, reducing the space occupied by the components, significantly improving the system power density, and adapting to the application scenarios of high integration in data centers.

[0019] 3. The topology of this invention can be expanded by cascading multiple switched capacitor units to flexibly achieve ultra-high step-down ratio configuration; combined with the working mode of hybrid step-down of switched capacitor network and coupled inductor, it effectively breaks through the technical bottleneck of limited step-down ratio of traditional converter, and can be perfectly adapted to the large step-down working condition of 48V bus to low voltage bus in data center, with wider topology adaptability and application range. Attached Figure Description

[0020] Figure 1 This is a circuit diagram of a non-isolated hybrid switched capacitor converter with cascaded switched capacitor units according to the present invention; Figure 2 For the present invention Figure 1 A schematic diagram of a single switched capacitor unit circuit in a converter switched capacitor network; Figure 3 For the present invention Figure 1 Timing diagram of the converter circuit; Figure 4(a) shows the present invention. Figure 1 Equivalent circuit diagram of converter operating mode 1; Figure 4(b) shows the present invention. Figure 1 Equivalent circuit diagram of converter operating mode 2; Figure 5(a) shows the present invention. Figure 1 The converter in the drive signal and Equivalent circuit diagram during the dead time between high levels; Figure 5(b) shows the present invention. Figure 1 The converter in the drive signal and Equivalent circuit diagram during the dead time between high levels. Detailed Implementation

[0021] The relevant technologies of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] like Figure 1 As shown in Figure 5, the non-isolated hybrid switched capacitor converter of the cascaded switched capacitor unit in this embodiment includes: a flying capacitor C 1,1 ~C n,2 Switching transistor Q 1,1 ~Q n+1,2 and SR a and SR b Coupled inductors L1 and L2, input terminal V in Output terminal V o Grounding terminal and filter capacitor C o and load R o The load terminal is composed of the switching transistor Q. 1,1 One end is connected to the input terminal V in Switching transistor Q 1,2 One end, the switching transistor Q 1,1 The other end is connected to the flying capacitor C 1,1 One end, switching transistor Q 2,1 One end of the switch Q. 1,2 The other end is connected to the flying capacitor C 1,2 One end, switching transistor Q 2,2 One end of the switch Q. 2,1 The other end is connected to the flying capacitor C 1,2 The other end, the switching transistor Q 3,1 One end, flying capacitor C 2,1 One end of the switch Q. 2,2 The other end is connected to the flying capacitor C 1,1 At the other end, the flying capacitor C 2,2 One end, switching transistor Q 3,2 One end of the switch Q. 3,1 The other end is connected to the flying capacitor C 2,2 At the other end, the switching transistor Q 3,2 Connecting flying capacitor C 2,1The other end... continues until it is connected to the switching transistor Q according to the above pattern. n,1 One end, flying capacitor C n 1,1 One end is connected to the switch transistor Q. n,2 One end, flying capacitor C n 1,2 One end of the switch Q. n,1 The other end is connected to the flying capacitor C n 1,2 At the other end, the flying capacitor C n,1 One end, switching transistor Q n+1,1 One end of the switch Q. n,2 The other end is connected to the flying capacitor C n 1,1 At the other end, the flying capacitor C n,2 One end, switching transistor Q n+1,2 One end of the switch Q. n+1,1 The other end is connected to the switching transistor SR a One end, flying capacitor C n,2 The other end is the same-named terminal of the coupling inductor L1. Switch Q n+1,2 The other end is connected to the flying capacitor C n,1 The other end, the switching transistor SR a One end of the transistor is the opposite end of the coupling inductor L2. The switching transistor SR... a The other end is connected to the ground terminal, one end of the load, and the switching transistor SR. b The other end of the coupling inductor L1 is connected to the same-named end of the coupling inductor L2 and the other end of the load, thus establishing a coupling relationship between the coupling inductor L1 and the coupling inductor L2.

[0023] Assuming n is even, the driving signal Φ A When it is high, the switching transistor Q 1,1 Q 2,2 Q 3,1…… Q n,2 Q n+1,1 and switching transistor SR b Turn on; drive signal Φ A When it is low, the switching transistor Q 1,1 Q 2,2 Q 3,1…… Q n,2 Q n+1,1 and switching transistor SR b Off. Drive signal Φ B When it is high, the switching transistor Q 1,2 Q 2,1 Q3,2…… Q n,1 Q n+1,2 and switching transistor SR a On; drive signal Φ B When it is low, the switching transistor Q 1,2 Q 2,1 Q 3,2…… Q n,1 Q n+1,2 and switching transistor SR a Turn off.

[0024] Figure 2 for Figure 1 A schematic diagram of a single switched capacitor unit in a non-isolated hybrid switched capacitor converter with cascaded switched capacitor units, including: a switching transistor Q. n+1,1 Q n+1,2 With flying capacitor C n,1 C n,2 ; Switching transistor Q n+1,1 One end is connected to the flying capacitor C n,1 One end, flying across capacitor C n,1 The other end is connected to the switching transistor Q. n+1,2 One end, the switching transistor Q n+1,2 The other end is connected to the flying capacitor C n,2 One end, flying across capacitor C n,2 The other end is connected to the switching transistor Q. n+1,1 The other end. Switch Q n+1,1 and switching transistor Q n+1,2 Both ends are connected to other structures in the hybrid switched capacitor converter topology, and the step-down ratio increases by 2 for each cascaded switched capacitor unit.

[0025] Figure 3 for Figure 1 Timing diagram of a non-isolated hybrid switched-capacitor converter circuit with cascaded switched-capacitor units, and the switching transistor Q. 1,1 Q 2,2 Q 3,1…… Q n,2 Q n+1,1 and switching transistor SR b The driving waveforms are consistent, both being Φ. A Switching transistor Q 1,2 Q 2,1 Q 3,2…… Q n,1 Q n+1,2 and switching transistor SR a The driving waveforms are consistent, both being Φ. B The above two sets of driving waveforms Φ A With Φ B The waveforms are complementary, both with a 50% duty cycle, and both sets of waveforms have a certain dead time.s1 The current waveform flowing through the coupled inductor L1 is i s2 The current waveform flowing through the coupled inductor L2 is i Lm The excitation current waveform, i o This is the current waveform flowing to the load.

[0026] Figure 4(a) shows Figure 1 The non-isolated hybrid switched-capacitor converter circuit with cascaded switched-capacitor units uses the switching transistor Q. 1,1 Q 2,2 Q 3,1…… Q n,2 Q n+1,1 and switching transistor SR b Equivalent circuit diagram at power-on. Input voltage V at this time. in For flying capacitor C 1,1 C 2,2…… C n 1,1 C n,2 Discharge of coupling inductor L1, and flying capacitor C 1,1 C 2,2…… C n 1,1 C n,2 Charging. Flying capacitor C 1,2 C 2,1…… C n 1,2 C n,1 Discharge the coupled inductor L1. The current in coupled inductor L1 and the current induced in coupled inductor L2 flow together to the load, and the excitation current direction is from coupled inductor L1 to coupled inductor L2.

[0027] Figure 4(b) shows Figure 1 The non-isolated hybrid switched-capacitor converter circuit with cascaded switched-capacitor units uses the switching transistor Q. 1,2 Q 2,1 Q 3,2…… Q n,1 Q n+1,2 and switching transistor SR a Equivalent circuit diagram at power-on. Input voltage V at this time. in For flying capacitor C 1,2 C 2,1…… C n 1,2 C n,1 Discharge of coupling inductor L2, and flying capacitor C 1,2 C 2,1…… C n 1,2C n,1 Charging. Flying capacitor C 1,1 C 2,2…… C n 1,1 C n,2 Discharge the coupled inductor L2. The current in the coupled inductor L2 and the current induced in the coupled inductor L1 flow together to the load, and the excitation current direction is from the coupled inductor L2 to the coupled inductor L1.

[0028] Figure 5(a) shows the non-isolated hybrid switched capacitor converter circuit with cascaded switched capacitor units under the drive signal Φ. A With Φ B The equivalent circuit diagram during the dead time between high-level signals is shown. During the dead time, it can be approximated as a constant voltage across the flying capacitor and a constant magnetizing current in the magnetizing inductor, i.e., equivalent to an ideal voltage source and an ideal current source, respectively. The circuit includes the input voltage source and the flying capacitor and switching transistor Q, which are equivalent to voltage sources. 1,1 Output capacitor C at both ends Q(1,1) Switching transistor Q 1,2 Output capacitor C at both ends Q(1,2) Switching transistor Q 2,1 Output capacitor C at both ends Q(2,1) Switching transistor Q 2,2 Output capacitor C at both ends Q(2,2)…… Switching transistor Q n,1 Output capacitor C at both ends Q(n,1) Switching transistor Q n,2 Output capacitor C at both ends Q(n,2) Switching transistor Q n+1,1 Output capacitor C at both ends Q(n+1,1) SR switching transistor a Output capacitor C at both ends SRa SR switching transistor b Output capacitor C at both ends SRb And equivalent to current source I Lm The magnetizing inductance. Current source I Lm For output capacitor C Q(1,1) C Q(2,2)…… C Q(n,2) C Q(n+1,1) C SRb Charging. Current source I Lm Simultaneously, the output capacitor C Q(1,2) C Q(2,1)…… C Q(n,1) C Q(n+1,2) C SRa Discharge to achieve zero-voltage turn-on.

[0029] Figure 5(b) shows the non-isolated hybrid switched capacitor converter circuit with cascaded switched capacitor units under the drive signal Φ. BWith Φ A The equivalent circuit diagram during the dead time between high-level signals is shown. During the dead time, it can be approximated as a constant voltage across the flying capacitor and a constant magnetizing current in the magnetizing inductor, i.e., equivalent to an ideal voltage source and an ideal current source, respectively. The circuit includes the input voltage source and the flying capacitor and switching transistor Q, which are equivalent to voltage sources. 1,1 Output capacitor C at both ends Q(1,1) Switching transistor Q 1,2 Output capacitor C at both ends Q(1,2) Switching transistor Q 2,1 Output capacitor C at both ends Q(2,1) Switching transistor Q 2,2 Output capacitor C at both ends Q(2,2)…… Switching transistor Q n,1 Output capacitor C at both ends Q(n,1) Switching transistor Q n,2 Output capacitor C at both ends Q(n,2) Switching transistor Q n+1,1 Output capacitor C at both ends Q(n+1,1) SR switching transistor a Output capacitor C at both ends SRa SR switching transistor b Output capacitor C at both ends SRb And equivalent to current source I Lm The magnetizing inductance. Current source I Lm For output capacitor C Q(1,1) C Q(2,2)…… C Q(n,2) C Q(n+1,1) C SRb Discharge achieves zero-voltage turn-on. Current source I Lm Simultaneously, the output capacitor C Q(1,2) C Q(2,1)…… C Q(n,1) C Q(n+1,2) C SRa Charge.

[0030] Under steady-state conditions, neglecting the effect of dead time, the following relationship can be obtained: (7) Therefore, the converter gain can be expressed as: (1) For the equivalent capacitance C in the working mode eq1 and C eq2 Due to the symmetry of the circuit, C eq1 =C eq2 Let the capacitance of all flying capacitors be C. F The equivalent capacity can be obtained through the following formula: (8) Assuming the leakage inductance of the coupled inductor is uniformly distributed, i.e., L k1 =L k2 =L r / 2, combined with equation (8), we can obtain the formula for calculating the resonant frequency of the converter: (9) The topology proposed in this invention can achieve soft switching of all switching transistors. Utilizing the excitation current of the magnetizing inductor, the output capacitors of all switching transistors can be soft-charged and discharged within the dead time. To achieve full capacitor soft-charge and discharge, the following calculation formula must be satisfied: (10) This invention addresses the shortcomings of current data center intermediate-stage voltage conversion, such as large size, low efficiency, fixed turns ratio, and complex drive circuits. It proposes a non-isolated hybrid switched-capacitor converter with cascaded switched-capacitor units. This converter combines a switched-capacitor network with magnetic components, allowing the switched-capacitor network to handle the main voltage drop, significantly reducing voltage stress on the switching transistors and decreasing reliance on large magnetic components, thus effectively improving power density. Furthermore, all main power switches implement soft switching, further enhancing conversion efficiency. The circuit topology allows for expansion of the switched-capacitor units, thereby changing the gain and reducing device stress. Simultaneously, the converter has only two operating modes, significantly reducing drive complexity.

[0031] In summary, this invention provides a scalable non-isolated hybrid switched-capacitor converter with a compact structure, high power density, excellent conversion efficiency, and low driving complexity. It is suitable for application scenarios with high requirements for size and efficiency, such as intermediate stage voltage conversion in data centers. The voltage conversion ratio can be flexibly adjusted by cascading switched-capacitor units, while maintaining the excellent soft-switching characteristics of all switching transistors, and has good prospects for engineering applications.

[0032] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A non-isolated hybrid switched-capacitor converter with cascaded switched-capacitor units, characterized in that, include: Flying capacitor C 1,1 ~C n,2 Switching transistor Q 1,1 ~Q n+1,2 SR switching transistor a SR b Coupled inductors L1 and L2, input voltage source V in Output terminal V o Grounding terminal, filter capacitor C o and load R o The coupled inductors L1 and L2 are mutually coupled; n is an integer greater than or equal to 1. The circuit connection of the converter is as follows: switching transistor Q 1,1 One end is connected to the input voltage source V in Positive electrode, switching transistor Q 1,1 The other end is connected in series with the switching transistor Q. 2,1 Q 3,1 , …… Q n+1,1 The same terminal of the coupling inductor L1 is connected afterward; the switching transistor Q 1,2 One end is connected to the input voltage source V in Positive electrode, switching transistor Q 1,2 The other end is connected in series with the switching transistor Q. 2,2 Q 3,2 , …… Q n+1,2 Connect the opposite-named terminal of the coupling inductor L2, and connect the same-named terminal of the coupling inductor L2 to the opposite-named terminal of the coupling inductor L1. Flying capacitor C 1,1 The two ends are respectively connected to the switching transistor Q. 1,1 Q 2,1 Connection node and switching transistor Q 2,2 Q 3,2 The connection node, the flying capacitor C 1,2 The two ends are respectively connected to the switching transistor Q. 2,1 Q 3,1 Connection node and switching transistor Q 1,2 Q 2,2 Connection node; Flying capacitor C 2,1 The two ends are respectively connected to the switching transistor Q. 2,1 Q 3,1 Connection node and switching transistor Q 3,2 Q 4,2 The connection node, the flying capacitor C 2,2 The two ends are respectively connected to the switching transistor Q. 3,1 Q 4,1 Connection node and switching transistor Q 2,2 Q 3,2 The connection nodes are cascaded sequentially according to the above cross-connection rules, until the flying capacitor C is reached. n-1,1 The two ends are respectively connected to the switching transistor Q. n-1,1 Q n,1 Connection node and switching transistor Q n,2 Q n+1,2 The connection node, the flying capacitor C n-1,2 The two ends are respectively connected to the switching transistor Q. n,1 Q n+1,1 Connection node and switching transistor Q n-1,2 Q n,2 Connection node; Flying capacitor C n,1 The two ends are respectively connected to the switching transistor Q. n,1 Q n+1,1 Connection node and switching transistor Q n+1,2 The connection node of the coupled inductor L2, and the flying capacitor C n,2 The two ends are respectively connected to the switching transistor Q. n+1,1 The connection node of the coupling inductor L1 and the switching transistor Q n,2 Q n+1,2 ; connection nodes; Filter capacitor C o With load R o After parallel connection, one end is grounded and the other end is connected to the connection node of coupling inductors L1 and L2; filter capacitor C o One end is grounded, and the other end is connected to the output terminal V. o ; Switching transistor SR a One end is grounded and the other end is connected to the switching transistor Q. n+1,1 Connection node of coupling inductor L1; switching transistor SR b One end is grounded and the other end is connected to the switching transistor Q. n+1,2 The connection node of the coupled inductor L2.

2. The non-isolated hybrid switched-capacitor converter with cascaded switched-capacitor units according to claim 1, characterized in that, In the converter, a single switched capacitor unit includes a switching transistor Q. n+1,1 Q n+1,2 With flying capacitor C n,1 C n,2 Each cascaded switched capacitor unit increases the converter's step-down ratio by 2 times.

3. A non-isolated hybrid switched-capacitor converter with cascaded switched-capacitor units according to claim 1, characterized in that, When n is even; the switching transistor Q 1,1 Q 2,2 Q 3,1 Q n,2 Q n+1,1 SR switching transistor b Common driving waveform Φ A ; Switching transistor Q 1,2 Q 2,1 Q 3,2 Q n,1 Q n+1,2 SR switching transistor a Common drive waveform Φ B ; driving waveform Φ A With driving waveform Φ B They are complementary, with a duty cycle of 50% for both, and a dead time is set between the two sets of drive waveforms.

4. A non-isolated hybrid switched-capacitor converter with cascaded switched-capacitor units according to claim 3, characterized in that, During the dead time, the excitation current I of the coupled inductor is relied upon. Lm Complete the soft-charge and discharge of the output capacitors of all switching transistors to achieve zero-voltage turn-on of all switching transistors; ignoring leakage inductance, the soft-switching conditions are as follows: （6） In the formula, L m C is the magnetizing inductance value. Q(i,1) C Q(i,2) C SRa C SRb These are the output capacitors for the corresponding switching transistors; U Q(i,1) U Q(i,2) U SRa U SRb This is the voltage difference required for the output capacitor of the corresponding switching transistor to fully charge and discharge.

5. A non-isolated hybrid switched-capacitor converter with cascaded switched-capacitor units according to claim 1, characterized in that, The converter voltage gain satisfies: （1） In the formula, n is the number of cascaded switched capacitor units.

6. A non-isolated hybrid switched-capacitor converter with cascaded switched-capacitor units according to claim 1, characterized in that, The converter circuit operates symmetrically on both sides; all flying capacitors C 1,1 ~C n,2 The steady-state voltages are equal, satisfying: （2） Flying capacitor C n,1 With C n,2 The effective values ​​of the corresponding branch currents are equal, but the phase difference is 180°.

7. A non-isolated hybrid switched-capacitor converter with cascaded switched-capacitor units according to claim 1 or 6, characterized in that, All flying capacitors in the converter have a capacitance value of C. F ; driving waveform Φ A The equivalent capacitance C of the flying capacitor network at high level eq1 , driving waveform Φ B Equivalent capacitance C at high level eq2 satisfy: （3） （4） In the formula, n is the number of cascaded switched capacitor units.

8. A non-isolated hybrid switched-capacitor converter with cascaded switched-capacitor units according to claim 1, characterized in that, The converter's coupling inductance and leakage inductance are equally distributed, L k1 =L k2 =L r / 2, the resonant frequency of the converter satisfies: （9） In the formula, L r For the total equivalent leakage inductance, C F This refers to the capacitance value of a single flying capacitor.

9. A non-isolated hybrid switched-capacitor converter with cascaded switched-capacitor units according to any one of claims 1 to 8, characterized in that, The converter is used for intermediate voltage transformation in a two-stage power supply architecture for a 48V bus in a data center.

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