Switched capacitor multi-phase high voltage gain bidirectional dc-dc converter

Abstract

The application discloses a switched capacitor type multi-phase high-voltage gain bidirectional DC-DC converter and belongs to the technical field of DC-DC converters. fn‑1 A negative electrode; inductances L2, L3...L n Multi-phase expansion is realized through staggered parallel connection, and n-1 switch capacitor networks are realized through stepped connection mode; the converter can realize bidirectional flow of quantity through the switch capacitor structure, can realize high-voltage gain, can select appropriate phase number according to the output voltage demand of an application occasion, can reduce the voltage stress of a switch device while high-voltage output is met, and the control mode of the converter does not change with the increase of the phase number, the control complexity is low, and a closed-loop controller is easy to design.

Description

Technical Field

[0001] The present invention belongs to the technical field of DC-DC converters, and in particular relates to a switched capacitor type multi-phase high voltage gain bidirectional DC-DC converter. Background Art

[0002] In recent years, with the advancement of carbon emission control efforts, new energy sources have been promoted and applied globally. DC microgrid systems, centered around photovoltaic and wind power generation technologies, are the most widely used. In DC microgrid systems, energy storage systems are required to optimize the DC bus voltage and output power, enhancing the system's ability to cope with load disturbances and ensuring stable operation. Currently, battery energy storage is the most stable and widely used energy storage technology, but energy storage batteries have the characteristics of low voltage (12-48V) and high current. Although high voltage can be achieved by connecting multiple batteries in series, when charging as a single unit, the parameters of each series battery module must be essentially consistent. Otherwise, charging imbalance may occur, potentially leading to explosion or fire. While using multiple batteries in parallel can enhance power redundancy and mitigate issues caused by connecting batteries in series, their output voltage is relatively low.

[0003] Therefore, in DC microgrid systems, a bidirectional DC-DC converter with high voltage gain is required to boost the battery voltage to match the higher-level DC bus voltage and ensure stable system output voltage and power. Considering diverse application areas and user needs, in addition to high voltage gain, other characteristics must be considered, such as high efficiency, high power density, scalable structure, switch voltage stress, and the capacity and withstand voltage of the high-voltage side filter capacitor.

[0004] In existing research on high-gain DC-DC converters, high voltage transformation ratios are mainly achieved through quasi-Z source structures, coupled inductor structures, and switched capacitor structures. Among them, the quasi-Z source structure has a low step-up transformation ratio and is not suitable for situations with higher voltage gain; the coupled inductor structure has leakage inductance problems such as voltage spikes and losses; and the switched capacitor structure has a large number of power switching devices and complex control issues.

[0005] In summary, it is of great significance to develop a high-gain bidirectional DC-DC converter that can achieve high voltage gain, high efficiency, scalable structure and low control complexity. Summary of the Invention

[0006] In view of the above technical problems existing in the prior art, the present invention proposes a switched capacitor multi-phase high voltage gain bidirectional DC-DC converter, which has a reasonable design, overcomes the shortcomings of the prior art, and has good effects.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A switched-capacitor multiphase high-voltage gain bidirectional DC-DC converter, the main circuit topology of the converter includes n inductors L1, L2, L3, …, L n , 3n-1 switch tubes S1, S2, S3, …, S n+1 , S Cf1 , S Cf2 , S Cf3 , …, S Cf2n-2 , n-1 intermediate switch capacitors C f1 , C f2 , …, C fn-1 , n high-voltage side capacitors C1, C2, C3, …, C n , power supplies V high , V low and loads R high , R low ;

[0009] Among them, the first end of the n inductors is connected to the common end composed of the positive pole of the low-voltage side power supply V low and one end of the load R low ; the second end of the first inductor L1 is connected to the common end composed of the drain of the switch tube S1 and the source of S n+1 , while the source of S1 is directly connected to the negative pole of the intermediate switch capacitor C fn-1 ; the drain of S n+1 is connected to the common end composed of the positive pole of the high-voltage side capacitor C1, the positive pole of the high-voltage side power supply V high , and one end of the load R high ; the common end composed of the negative pole of V high and the other end of R high is connected to the negative pole of the high-voltage side capacitor C n in the last phase switch capacitor network;

[0010] The second, third, …, n inductors, switch tubes S2, S3, …, S n and intermediate switch capacitors C f1 , C f2 , …, C fn-1 are realized by interleaved parallel connection to realize multiphase expansion; specifically, the second end of the ith inductor is connected to the common end composed of the drain of the switch tube S i and the positive pole of the intermediate capacitor C fi-1 , while the source of S i is connected to the common end composed of the negative pole of the low-voltage side power supply V low and the other end of the load R low ; wherein 2≤i≤n;

[0011] The negative pole of the first switch capacitor C f1 is connected to the switch tube SCf1 The source and switch tube S Cf2 The drain of the common terminal, while S Cf1 The drain and low voltage side power supply V low The negative electrode and the load R low The other end of the common end and S2, S3, ..., S n Source connection; S Cf2 The source is connected to the negative electrode of the high-voltage side capacitor C2, and the positive electrode of C2 and the negative electrode of capacitor C1 form a common terminal connected to the low-voltage side power supply V low The negative electrode and the load R low The other end of the common end;

[0012] Intermediate switch capacitor C f2 、C f3 ,…,C fn-1 , high voltage side capacitors C3, C4, ..., C n and switch tube S Cf3 、S Cf4 ,…,S Cf2n-2 The switched capacitor network composed of the two switches is connected in a stepped manner to achieve multi-phase expansion; specifically, the j-th intermediate switched capacitor C fj The negative electrode is connected to the switch tube S Cf2j-1 The source and switch tube S Cf2j The drain of the common terminal, while S Cf2j-1 The drain is connected to the high side capacitor C on a switched capacitor network j The negative electrode and the switch tube S Cf2j-2 The common terminal composed of the source; S Cf2j The source is connected to C j+1 The negative electrode, C j+1 The positive electrode and C j The negative electrode of the common terminal is connected to the switch tube S Cf2j-1 drain; where 2≤j≤n-1.

[0013] Preferably, all the switches of the converter only need one complementary control signal to control the switching on and off of the devices; specifically, the switches S1, S2, S3, ..., S n and S Cf2 、S Cf4 ,…,S Cf2n-2 The control signal is the same as S n+1 、S Cf1 、S Cf3 ,…,S Cf2n-3 The control signal of the converter is complementary; the range of the duty cycle D of the converter control signal is 0≤D≤1, that is, the full duty cycle range operation can be achieved by adjusting the control signal.

[0014] Preferably, the converter's operating mode is divided into a boost operating mode and a buck operating mode according to the different energy flow directions on the high-voltage side and the low-voltage side:

[0015] When energy flows from the low-voltage side to the high-voltage side, the converter operates in boost mode, and the voltage gain expression is:

[0016]

[0017] Where M is the ratio of the high voltage side voltage to the low voltage side voltage, n is the number of extended phases, and D Boost is the boost duty cycle;

[0018] When energy flows from the high-voltage side to the low-voltage side, the converter operates in buck mode, and the buck ratio expression is:

[0019]

[0020] Where M is the ratio of the low voltage side voltage to the high voltage side voltage, n is the number of extended phases, and D Buck is the boost duty cycle.

[0021] Preferably, when the converter performs multi-phase expansion, the voltage stress expression of the switch tube in the expanded phase is:

[0022]

[0023] Where n is the number of extended phases, V S2 、V S3 …V Sn and V Scf1 、V Scf2 …V Scf2n-2 It represents the voltage amplitude of the switch tube in the extended phase, and D is the duty cycle of the converter.

[0024] The beneficial technical effects brought about by the present invention are:

[0025] 1. The present invention can achieve higher gain with the same number of components and the same duty cycle, effectively solving the problem of limited boost ratio of the converter due to the extreme duty cycle, and realizing a wide range of converter voltage output;

[0026] 2. It is scalable and can determine the number of converter phases according to load requirements. At the same time, the control method does not change with the increase in the number of phases, making it easy to design a closed-loop controller;

[0027] 3. Through multi-phase expansion, the voltage stress of the switching device can be reduced, the on-state resistance of the switching device can be reduced, and the efficiency of the converter can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1This is a circuit diagram of a switched capacitor multi-phase high voltage gain bidirectional DC-DC converter proposed by the present invention;

[0029] Figure 2 A specific implementation of the proposed converter corresponding to the four-phase topology;

[0030] Figure 3 The key waveforms of the proposed converter in boost mode corresponding to the four-phase topology;

[0031] Figure 4 The key waveforms of the proposed converter in buck mode corresponding to the four-phase topology;

[0032] Figure 5 The circuit modal diagram of the proposed switched capacitor four-phase high voltage gain converter in boost mode;

[0033] Figure 5 (a) is circuit mode 1; Figure 5 (b) is circuit mode 2;

[0034] Figure 6 The circuit modal diagram of the proposed switched capacitor four-phase high voltage gain converter in buck mode;

[0035] Figure 6 (a) is circuit mode 1; Figure 6 (b) is circuit mode 2;

[0036] Figure 7 The simulation results of the proposed converter in boost mode corresponding to the four-phase topology are shown;

[0037] Figure 7 (a) is the voltage gain simulation waveform; Figure 7 (b) is the simulated waveform of the inductor current; Figure 7 (c) in the figure is the simulated waveform of the inductor voltage; Figure 7 (d) is the voltage stress simulation waveform of the main switching device;

[0038] Figure 8 The simulation results of the proposed converter in buck mode corresponding to the four-phase topology are shown;

[0039] Figure 8 (a) is the voltage gain simulation waveform; Figure 8 (b) is the simulated waveform of the inductor current; Figure 8 (c) in the figure is the simulated waveform of the inductor voltage; Figure 8 (d) is the voltage stress simulation waveform of the main switching device. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0041] Example 1

[0042] The topology of a switched capacitor multiphase high voltage gain bidirectional DC-DC converter proposed in an embodiment of the present invention is as follows: Figure 1 The main circuit topology of the converter includes n inductive elements L1, L2, L3, ..., L n , 3n-1 switch tubes S1, S2, S3, ..., S n+1 and S Cf1 、S Cf2 、S Cf3 ,…,S Cf2n-2 , n-1 intermediate switch capacitors C f1 、C f2 ,…,C fn -1, n high-voltage side capacitors C1, C2, C3, ..., C n , power supply V high 、V low and load R high 、R low ;

[0043] Among them, the first end of n inductors is connected to the low-voltage side power supply V low The positive electrode and the load R low The second end of the first inductor L1 is connected to the drain of the switch tube S1 and S n+1 The source of S1 is directly connected to the middle switch capacitor C fn-1 Negative connection of S n+1 The drain is connected to the positive electrode of the high-voltage side capacitor C1 and the high-voltage side power supply V high The positive electrode, load R high The common terminal is composed of one end of high The negative electrode, R high The other end of the common end is connected to the high-voltage side capacitor C in the last phase switch capacitor network. n The negative electrode;

[0044] The second, third, ..., nth inductors, switches S2, S3, ..., S n and the intermediate switch capacitor C f1 、C f2 ,…,C fn-1 Multi-phase expansion is achieved by staggered parallel connection; specifically, the second end of the i-th (2≤i≤n) inductor is connected to the switch tube S i The drain and the intermediate capacitor C fi-1 The positive electrode of the common terminal, while S i The source is connected to the low-side power supply Vlow The negative electrode and the load R low The other end of the common end;

[0045] The first switching capacitor C f1 The negative electrode is connected to the switch tube S Cf1 The source and switch tube S Cf2 The drain of the common terminal, while S Cf1 The drain and low-voltage side power supply V low The negative electrode and the load R low The other end of the common end and S2, S3, ..., S n Source connection; S Cf2 The source is connected to the negative electrode of the high-voltage side capacitor C2, and the positive electrode of C2 and the negative electrode of capacitor C1 form a common terminal connected to the low-voltage side power supply V low The negative electrode and the load R low The other end of the common end;

[0046] Intermediate switch capacitor C f2 、C f3 ,…,C fn-1 , high voltage side capacitors C3, C4, ..., C n and switch tube S Cf3 、S Cf4 ,…,S Cf2n-2 The switched capacitor network composed of the two switches is connected in a stepped manner to achieve multi-phase expansion; specifically, the jth (2≤j≤n-1) intermediate switched capacitor C fj The negative electrode is connected to the switch tube S Cf2j-1 The source and switch tube S Cf2j The drain of the common terminal, while S Cf2j-1 The drain is connected to the high side capacitor C on a switched capacitor network j The negative electrode and the switch tube S Cf2j-2 The common terminal composed of the source of Cf2j The source is connected to C j+1 The negative electrode, C j+1 The positive electrode and C j The negative electrode of the common terminal is connected to the switch tube S Cf2j-1 of the drain.

[0047] All the switches of the proposed converter only need one complementary control signal to control the on and off of the devices; specifically, the switches S1, S2, S3, ..., S n and S Cf2 、S Cf4 ,…,S Cf2n-2 The control signal is the same as S n+1 、S Cf1 、S Cf3 ,…,SCf2n-3 The control signals of the proposed converter are complementary; the duty cycle D range of the control signal of the converter is 0≤D≤1, and the full duty cycle range operation can be achieved by adjusting the control signal.

[0048] Under the above control mode, the proposed converter can be divided into boost mode and buck mode according to the energy flow direction between the high-voltage side and the low-voltage side:

[0049] When energy flows from the low-voltage side to the high-voltage side, the converter operates in boost mode, and the voltage gain expression is:

[0050]

[0051] Where M is the ratio of the high voltage side voltage to the low voltage side voltage, n is the number of extended phases, and D Boost is the boost duty cycle;

[0052] When energy flows from the high-voltage side to the low-voltage side, the converter operates in buck mode, and the buck ratio expression is:

[0053]

[0054] Where M is the ratio of the low voltage side voltage to the high voltage side voltage, n is the number of extended phases, and D Buck is the boost duty cycle.

[0055] In the above working mode, when the proposed converter performs multi-phase expansion, the voltage stress expression of the switch tube in the expanded phase is:

[0056]

[0057] Where n is the number of extended phases, V S2 、V S3 …V Sn and V Scf1 、V Scf2 …V Scf2n-2 It represents the voltage amplitude of the switch tube in the extended phase, and D is the duty cycle of the converter.

[0058] Example 2

[0059] In order to more clearly describe the technical solutions and advantages of the present invention, Figure 2 The switched capacitor type four-phase high voltage gain bidirectional DC-DC converter topology shown in the figure is Figure 3 、 Figure 4 The key waveforms of the boost and buck working modes are shown in the figure. Figure 5 、 Figure 6 The boost and buck operating modes shown in the circuit diagrams and Figure 7 、 Figure 8The simulation waveforms shown are used to analyze and illustrate a typical embodiment of the present invention.

[0060] The switched capacitor type four-phase high voltage gain bidirectional DC-DC converter topology provided in the embodiment is as follows: Figure 2 As shown, the converter main circuit topology includes 4 inductors L1, L2, L3, L4, 11 switches S1, S2, S3, ..., S5, S Cf1 、S Cf2 、S Cf3 ,…,S Cf6 , 3 intermediate switch capacitors C f1 、C f2 、C f3 , 4 high-voltage side capacitors C1, C2, C3, C4, power supply V high 、V low and load R high 、R low ;

[0061] Among them, the first ends of the above four inductors are connected to the low-voltage side power supply V low or load R low The positive end of the first inductor L1 is connected together; the second end of the first inductor L1 is connected to the drain of the switch tube S1 and S n+1 The source of S1 is directly connected to the C of the switch capacitor network. f3 The negative electrode is connected; the drain of S5 is connected to the positive electrode of the high-voltage side capacitor C1 and the high-voltage side power supply V high or load R high The common point of high or R high The negative end is connected to the negative electrode of capacitor C4 in the last phase switch capacitor network;

[0062] Inductors L2, L3, L4, switches S2, S3, S4 and intermediate switch capacitor C f1 、C f2 、C f3 Multi-phase expansion is achieved by staggered parallel connection; specifically, the second ends of the inductors L2, L3, and L4 are connected to the drains of the switches S2, S3, and S4 and the intermediate capacitor C f1 、C f2 、C f3 At the common point of the positive electrode, the source of S2, S3, and S4 are connected to V low or R low The negative terminal is connected;

[0063] The first switched capacitor C f1 Negative electrode and switch tube S Cf1 Source and switch tube S Cf2 The drain terminals are connected to the common point, and S Cf1 The drain and V lowor R low The negative terminal and the source of S1, S2, S3, and S4 are connected to the low-voltage side power supply V low or load R low The negative terminal; S Cf2 The source is connected to the negative electrode of the high-voltage side capacitor C2; the positive electrode of C2 is connected to the negative electrode of capacitor C1 and V low or R low At the common point of the negative terminal;

[0064] Intermediate switch capacitor C f2 、C f3 , high-voltage side capacitors C3, C4 and switch tube S Cf3 、S Cf4 、S Cf5 、S Cf6 The switched capacitor network composed of the two phases is expanded by step-by-step connection; specifically, the intermediate switched capacitor C f2 The negative electrode and the switch tube S Cf3 Source and switch tube S Cf4 The drain terminals are connected at the common point, and the switch S Cf3 The drain is connected to a switch capacitor network high voltage side capacitor C2 negative electrode and switch tube S Cf2 Between the source and the switch tube S Cf4 The source of is connected to the negative electrode of C3, while the positive electrode of C3 is connected to the negative electrode of C2 and the switch tube S Cf3 At the drain common point; the middle switch capacitor C f3 The negative electrode and the switch tube S Cf5 Source and switch tube S Cf6 The drain terminals are connected at the common point, and the switch S Cf5 The drain is connected to a switch capacitor network high voltage side capacitor C3 negative electrode and switch tube S Cf4 Between the source and the switch tube S Cf6 The source of is connected to the negative electrode of C4, while the positive electrode of C4 is connected to the negative electrode of C3 and the switch tube S Cf5 The drain common point.

[0065] All the switch tubes of the four-phase topology converter provided in this embodiment only need one complementary control signal to control the device to be turned on and off; specifically, the switch tubes S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15, S16, S17, S18, S19, S20, S21, S22, S33, S44, Cf2 、S Cf4 、S Cf6 The control signal is the same as S5 and S Cf1 、S Cf3 、S Cf5The control signals of the converter are complementary; the duty cycle D range of the converter control signal provided is 0≤D≤1, and the full duty cycle range can be achieved by adjusting the control signal. Under this control mode, the operating mode of the converter provided is divided into boost mode and buck mode according to the different energy flow directions on the high-voltage side and the low-voltage side:

[0066] The key waveforms of the four-phase topology converter provided in this embodiment in the boost working mode are as follows: Figure 3 As shown, the corresponding circuit mode is as follows Figure 5 shown.

[0067] Circuit mode 1[t0-t1]: Figure 5 As shown in (a), the switch tubes S1, S2, S3, S4, S Cf2 、S Cf4 、S Cf6 On, S5, S Cf1 、S Cf3 、S Cf5 Shutdown; V low Charge the inductors L1, L2, L3, and L4, and the intermediate switch capacitor C f3 Charge the inductor L1, C f1 The high-voltage side capacitor C2 is charged through S2 and S7. f2 Through S3, S Cf4 Charge the high-voltage side capacitors C2 and C3, and C1 is R high powered by.

[0068] Circuit mode 2[t1-t2]: Figure 5 As shown in (b), the switch tubes S1, S2, S3, S4, S Cf2 、S Cf4 、S Cf6 Shutdown, S5, S Cf1 、S Cf3 、S Cf5 conduction; V low Charge the inductors L1, L2, L3, and L4; L1 forms a loop through S5 to form a load R high Power supply, while charging capacitor C1, L2, L3, L4 to the middle switch capacitor C f1 、C f2 、C f3 Charging. High-voltage side capacitors C1, C2, C3, and C4 are connected to R high powered by.

[0069] The key waveforms of the four-phase topology converter provided in this embodiment in the buck working mode are as follows: Figure 4 As shown, the corresponding circuit mode is as follows Figure 6 shown.

[0070] Circuit mode 1[t0-t1]: Figure 6 As shown in (a), the switch tubes S5 and S Cf1 、S Cf3 、S Cf5 On, S1, S2, S3, S4, S Cf2 、S Cf4 、S Cf6 Shutdown; V high The capacitors C1, C2, C3 and C4 store energy. C1 connects to R through S5. low Power supply and charge inductor L1, capacitor C in the switched capacitor network f1 、C f2 、C f3 Through S Cf1 、S Cf3 、S Cf5 A loop is formed to charge the inductors L2, L3, and L4. At the same time, C f2 、C f3 Charge the high-voltage side capacitors C2 and C3 and R low powered by.

[0071] Circuit mode 2[t1-t2]: Figure 6 As shown in (b), the switch tubes S5 and S Cf1 、S Cf3 、S Cf5 Shutdown, S1, S2, S3, S4, S Cf2 、S Cf4 、S Cf6 conduction; V high The capacitors C1, C2, C3, and C4 store energy, and the inductor L1 charges the switch capacitor Cf3 through S1 and S4 and charges R low Power supply, inductors L2, L3, L4 respectively form a loop through S2, S3, S4 as R low Power supply. Capacitor C2 is connected to C through S2 and S7. f1 Charging, capacitors C2 and C3 are connected to C through S3 and S9. f2 Charging, capacitors C2, C3, C4 through S4, S 11 C f3 Charge.

[0072] The switched capacitor type four-phase high voltage gain bidirectional DC-DC converter of this embodiment is simulated and verified. The component parameters are as follows: the four energy storage inductors are all 600μH, the three intermediate capacitors, the four high-voltage side capacitors and the one low-voltage side filter capacitor are all 470μF, the switching frequency is 20k, the high-voltage side load is 100Ω, the high-voltage side input voltage is 510V, and the low-voltage side input voltage is 24V. The corresponding simulation results are shown in Figure 1. Figure 7 、 Figure 8 shown.

[0073] The voltage transformation ratio expression of the four-phase topology converter provided in this embodiment under the above control mode is:

[0074]

[0075] Among them, M represents the ratio of the high-voltage side voltage to the low-voltage side voltage, D represents the switching tubes S1, S2, S3, S4, S Cf2 、S Cf4 、S Cf6 When the duty cycle D = 0.6, the theoretical voltage gain is 21.25 times. Figure 7 (a) Figure 8 (a) Comparison of the low-voltage side voltage and high-voltage side voltage in the boost and buck working modes shows that the high-voltage side voltage is 510V and the low-voltage side voltage is 24V, which means that both working modes can achieve a voltage gain of 21.25 times. Figure 7 (b)-(c), Figure 8 The inductor current and inductor voltage waveforms in the boost working mode and buck working mode shown in (b)-(c) show that the simulation results are consistent with the theoretical analysis.

[0076] For this embodiment, the voltage stress expression of the switches S1, S2, S3, and S4 in the four-phase topology converter in the boost working mode and the buck working mode is as follows:

[0077]

[0078]

[0079] Among them, V S1 、V S2 、V S3 、V S4 Corresponding to the voltage amplitude of the switch tubes S1, S2, S3, and S4, D is the voltage amplitude of the switch tubes S1, S2, S3, S4, and S Cf2 、S Cf4 、S Cf6 When the duty cycle D = 0.6, the corresponding V S1 =450V, V S2 =V S3 =V S4 =60V, the drain-source voltage simulation waveforms of the switches S1, S2, S3, and S4 in boost mode and buck mode are as follows: Figure 7 (d) Figure 8 As shown in (d), it can be seen that the voltage amplitude of the switch tube S1 is 450V, and the voltage amplitudes of S2, S3, and S4 are 60V, which are consistent with the theoretical calculated values.

[0080] In summary, the simulation results are generally consistent with the theoretical analysis, verifying that the proposed converter topology can achieve a high voltage transformation ratio and bidirectional energy flow. Furthermore, the proposed converter has multiphase scalability, allowing the number of converter phases to be selected based on actual application needs. Therefore, the switched-capacitor multiphase high-gain bidirectional DC-DC converter proposed in this invention can be applied in high-voltage output applications, particularly in battery energy storage systems in DC microgrids.

[0081] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A switched capacitor multiphase high voltage gain bidirectional DC-DC converter, characterized in that: The main circuit topology of the converter includes n inductive elements L1, L2, L3, ..., L n , 3n-1 switch tubes S1, S2, S3, ..., S n+1 and S Cf1 、S Cf2 、S Cf3 ,…,S Cf2n-2 , n-1 intermediate switch capacitors C f1 、C f2 ,…,C fn-1 , n high-voltage side capacitors C1, C2, C3, ..., C n , power supply V high 、V low and load R high 、R low ; Among them, the first end of n inductors is connected to the low-voltage side power supply V low The positive electrode and the load R low The second end of the first inductor L1 is connected to the drain of the switch tube S1 and S n+1 The source of S1 is directly connected to the middle switch capacitor C fn-1 Negative connection of S n+1 The drain is connected to the positive electrode of the high-voltage side capacitor C1 and the high-voltage side power supply V high The positive electrode, load R high The common terminal is composed of one end of high The negative electrode, R high The other end of the common end is connected to the high-voltage side capacitor C in the last phase switch capacitor network. n The negative electrode; The second, third, ..., nth inductors, switches S2, S3, ..., S n and the intermediate switch capacitor C f1 、C f2 ,…,C fn-1 Multi-phase expansion is achieved by staggered parallel connection; specifically, the second end of the i-th inductor is connected to the switch tube S i The drain and the intermediate capacitor C fi-1 The positive electrode of the common terminal, while S i The source is connected to the low-side power supply V low The negative electrode and the load R low The other end of the common terminal; wherein, 2≤i≤n; The first switching capacitor C f1 The negative electrode is connected to the switch tube S Cf1 The source and switch tube S Cf2 The drain of the common terminal, while S Cf1 The drain and low-voltage side power supply V low The negative electrode and the load R low The other end of the common end and S2, S3, ..., S n Source connection; S Cf2 The source is connected to the negative electrode of the high-voltage side capacitor C2, and the positive electrode of C2 and the negative electrode of capacitor C1 form a common terminal connected to the low-voltage side power supply V low The negative electrode and the load R low The other end of the common end; Intermediate switch capacitor C f2 、C f3 ,…,C fn-1 , high voltage side capacitors C3, C4, ..., C n and switch tube S Cf3 、S Cf4 ,…,S Cf2n-2 The switched capacitor network composed of the two switches is connected in a stepped manner to achieve multi-phase expansion; specifically, the j-th intermediate switched capacitor C fj The negative electrode is connected to the switch tube S Cf2j-1 The source and switch tube S Cf2j The drain of the common terminal, while S Cf2j-1 The drain is connected to the high side capacitor C on a switched capacitor network j The negative electrode and the switch tube S Cf2j-2 The common terminal composed of the source of Cf2j The source is connected to C j+1 The negative electrode, C j+1 The positive electrode and C j The negative electrode of the common terminal is connected to the switch tube S Cf2j-1 The drain of the converter; where 2≤j≤n-1; the converter operation mode is divided into boost operation mode and buck operation mode according to the different energy flow directions on the high-voltage side and the low-voltage side: When energy flows from the low-voltage side to the high-voltage side, the converter operates in boost mode, and the voltage gain expression is: Where M is the ratio of the high voltage side voltage to the low voltage side voltage, n is the number of extended phases, and D Boost is the boost duty cycle; When energy flows from the high-voltage side to the low-voltage side, the converter operates in buck mode, and the buck ratio expression is: Where M is the ratio of the low voltage side voltage to the high voltage side voltage, n is the number of extended phases, and D Buck is the boost duty cycle; when the converter is multi-phase expanded, the voltage stress expression of the switch tube in the expanded phase is: Where n is the number of extended phases, V S2 、V S3 …V Sn and V Scf1 、V Scf2 …V Scf2n-2 It represents the voltage amplitude of the switch tube in the extended phase, and D is the duty cycle of the converter.

2. The switched capacitor multiphase high voltage gain bidirectional DC-DC converter according to claim 1, wherein: All the switches of the converter only need one complementary control signal to control the on and off of the devices; specifically, the switches S1, S2, S3, ..., S n and S Cf2 、S Cf4 ,…,S Cf2n-2 The control signal is the same as S n+1 、S Cf1 、S Cf3 ,…,S Cf2n-3 The control signal of the converter is complementary; the duty cycle D of the converter control signal is in the range of 0≤D≤1, that is, the full duty cycle range operation can be achieved by adjusting the control signal.

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