Single-stage non-isolated combined converter based on three-port switched capacitor network

Abstract

The invention discloses a single-stage non-isolated combined converter based on a three-port switched capacitor network. The single-stage non-isolated combined converter comprises the three-port switched capacitor network, a non-isolated DC-DC chopping converter, an output filter capacitor Co and a load resistor R. A traditional two-port switched capacitor network is transformed into the three-port switched capacitor network, and through cooperative operation of the three-port switched capacitor network and the DC-DC chopper converter, the DC voltage source and the switched capacitor network can be utilized to provide DC voltage input for the DC-DC chopper converter. Therefore, a voltage stabilizing capacitor between the switched capacitor network and the DC-DC chopper converter is omitted, a combined circuit of a single-stage structure is realized, the size of the converter is reduced, and the efficiency is improved. The single-stage non-isolated combined converter based on the three-port switched capacitor network can be combined with n switched capacitor units to obtain a multi-level circuit structure, and the voltage stress of a device is further reduced.

Description

Technical Field

[0001] The invention relates to a combined converter based on a resonant switched capacitor, in particular to a single-stage non-isolated combined converter based on a three-port switched capacitor network. Background Art

[0002] The energy density of capacitors is 10 to 1000 times that of inductors. Therefore, the switched capacitor converter that uses capacitors as the main energy storage element has a higher power density than the switched inductor converter that uses inductors to store energy. However, the switched capacitor converter has problems of inrush current and hard switching of the switch tube at the moment of capacitor charging and discharging. On this basis, a hollow inductor or stray inductance in the line is connected in series on the switched capacitor branch as a resonant inductor to form a resonant switched capacitor converter, which can eliminate the inrush current and has the advantages of soft switching of the switch tube, low electromagnetic noise of the converter and high power density.

[0003] When the resonant switched capacitor converter is used as a DC transformer (DCX), the working efficiency of the resonant switched capacitor converter is very high. For example, the switch slot converter based on the resonant switched capacitor network has the advantages of consistent switch tube voltage stress, modularization, and easy expansion, and is widely used in low-voltage DC conversion occasions such as data center power supply. However, the resonant switched capacitor converter used as a DC transformer (DCX) has a fixed input voltage and output voltage ratio, which is related to the circuit structure and cannot be adjusted.

[0004] Figure 1 It is a basic step-down resonant switched capacitor converter, and its input power voltage is V in , the output voltage of the converter is V o , the output filter capacitor is C o , the load resistance is R, and the switched capacitor network includes four switch tubes Q A , Q B , Q C , Q D , a resonant tank (consisting of a resonant inductor L r and resonant capacitor C r In order to obtain higher power conversion efficiency, the resonant switched capacitor converter needs to work in full resonance mode, that is, the resonant capacitor C r Both include a complete charging process and a complete discharging process.

[0005] 1) If Figure 2 As shown, when the resonant capacitor C r When charging, the power supply also supplies the resonant capacitor C r And load resistance R, then the voltage equation is:

[0006] V in =VCr +V o (1)

[0007] Where V Cr is the resonant capacitor C r Voltage Cr The average value of .

[0008] 2) If Figure 3 As shown, when the resonant capacitor C r When discharging, the resonant capacitor C r Supply power to the load resistor R, then the voltage equation is

[0009] V o =V Cr (2)

[0010] From the voltage relationship during the charging and discharging process of the resonant capacitor, it can be concluded that the input voltage of the basic step-down resonant switched capacitor converter is always equal to twice the output voltage, and the voltage cannot be adjusted.

[0011] V in =2V o (3)

[0012] According to the ampere-second balance principle of capacitors, when the basic step-down resonant switched capacitor converter enters steady-state operation, the resonant capacitor C r The average values ​​of the charge and discharge currents are equal, that is, the average value of the output current is twice the average value of the input current:

[0013] I o =2I in (4)

[0014] In the formula, I o is the average value of the output current, I in is the average value of the input current.

[0015] Although the voltage continuous regulation capability of the resonant switched capacitor converter can be achieved by changing the operating frequency, its voltage regulation capability is poor and the voltage regulation range is greatly affected by the load, especially when the switching frequency is very high during voltage regulation under light load conditions, which limits its application in more scenarios. At the same time, when the resonant switched capacitor converter is regulating the voltage, there is a very large circulating current in the converter's resonant tank circuit, resulting in large current conduction losses, which significantly reduces the converter's voltage regulation efficiency.

[0016] In contrast, the DC chopper converter has the advantages of a wide voltage regulation range and little influence by load conditions, but requires a large inductor as the main energy storage element, and the switching tube of the DC chopper converter generally operates in a hard switching mode, resulting in large switching losses, which is not conducive to the miniaturization and high frequency of the equipment.

[0017] In this regard, reference 1 (S. Han, Y. Wang, Y. Guan and D. Xu, "Analysis and Design of a Modular Switched Capacitor Converter With Adjustable Output Voltage in DC Microgrid," in IEEE Journal on Emerging and Selected Topics in Circuits and Systems, vol. 12, no. 1, pp. 232-241, March 2022.) and reference 2 (S. Han, Y. Wang, Z. Xie, Y. Guan, JM Alonso and D. Xu, "Continuously Adjustable Modular Bidirectional Switched-Capacitor DC–DC Converter," in IEEE Transactions on Power Electronics, vol. 37, no. 11, pp. 12944-12948, Nov. 2022.) propose a two-stage cascaded non-isolated combined converter based on a three-port switched capacitor network, such as Figure 4 As shown, the circuit consists of three parts: a three-port series switched capacitor network on the input side, a voltage-adjustable Buck converter, and a resonant switched capacitor converter. The front-stage circuit uses a three-port series switched capacitor network to divide the input voltage into two series switched capacitors according to a certain proportion, one of which is used for a fixed step-down conversion by a resonant switched capacitor converter at the rear stage, while the other switched capacitor adjusts the output voltage by a rear-stage Buck DC chopper circuit. Therefore, the two-stage cascaded non-isolated combined converter based on the three-port switched capacitor network solves the problem of small voltage regulation range of the traditional resonant switched capacitor converter. However, the three-port series switched capacitor network of the above-mentioned combined converter needs to use two large capacitors to provide stable DC voltage support for the rear-stage buck circuit, and the switch tube of the rear-stage Buck DC chopper circuit is a hard switch. In addition, the power supply on the input side cannot supply power to the load while charging the front-stage switched capacitor, and the front-stage circuit can only supply power to the load during the discharge of the switched capacitor, which makes the power conversion efficiency of the front-stage three-port series switched capacitor network low and the output ripple large.

[0018] Since the front-stage three-port series switch capacitor network and the rear-stage Buck DC chopper circuit drive signal in the two-stage structure combination converter of References 1 and 2 must work synchronously, the voltage regulation range of the rear-stage Buck DC chopper circuit is limited. Figure 5As shown, document 3 (S.Han, J.Tan, Y.Wang, Y.Guan and D.Xu, "Multifrequency Single-Stage Hybrid Switched-Capacitor Converter," in IEEETransactions on Power Electronics, vol.39, no.3, pp.3438-3451, March 2024.) is in Figure 4 Based on this, the positions of the back-stage Buck converter and the resonant switched capacitor converter are swapped, and an improved two-stage cascaded non-isolated combined converter based on a three-port switched capacitor network is proposed, such as Figure 5 As shown, the circuit also consists of three parts: a three-port series switched capacitor network on the input side, an adjustable voltage Buck converter, and a resonant switched capacitor converter. Figure 5 In the converter shown, the working states of the front-stage three-port series switch capacitor network and the rear-stage Buck DC chopper circuit are independent of each other, which enables the rear-stage Buck DC chopper circuit to operate in a wider voltage regulation range. However, the switch tubes in the combined converter are hard switches, and the switching loss is large. The two-stage structure combined converter has the same problem as the reference 1 and reference 2, that is, the power supply on the input side cannot supply power to the load while charging the front-stage switch capacitor, and the front-stage circuit can only supply power to the load during the discharge of the switch capacitor, which makes the power conversion efficiency of the front-stage series switch capacitor network low and the output ripple large. Summary of the invention

[0019] The purpose of the present invention is to provide a single-stage non-isolated combined converter based on a three-port switched capacitor network. The combined converter gives full play to the advantages of high power density and high efficiency in a non-voltage-regulated mode of a resonant switched capacitor converter. The resonant switched capacitor network is topologically combined with a DC-DC chopper converter through a partial power processing technology. The combined converter not only has the advantages of high power density and high efficiency in a non-voltage-regulated mode of a resonant switched capacitor network, but also has the advantages of a wide voltage regulation range of a DC-DC chopper converter and the advantages of soft switching.

[0020] The objective of the present invention is achieved through the following technical solutions:

[0021] A single-stage non-isolated combined converter based on a three-port switched capacitor network, comprising a three-port switched capacitor network, a non-isolated DC-DC chopper converter, an output filter capacitor C o and load resistance R, where:

[0022] The three-port switched capacitor network includes three switch tubes Q A , Q C , Q D, a resonant tank, the resonant tank consists of a resonant inductor L r and resonant capacitor C r composition;

[0023] The switch tube Q A The drain of the external power supply V in Phase connected, switch tube Q A The source of the resonant capacitor C r One end is connected to a non-isolated DC-DC chopper converter;

[0024] The resonant capacitor C r The other end of the resonant inductor L r One end of the resonant inductor L r The other end is connected to the switch tube Q C The source of the switch tube Q D The drain of is connected;

[0025] The switch tube Q C The drain of the output filter capacitor C o One end of the load resistor R is connected;

[0026] The switch tube Q D The source is grounded;

[0027] The output filter capacitor C o One end of the switch tube Q C The drain of the load resistor R is connected to one end of the non-isolated DC-DC chopper converter, and the other end of the output filter capacitor Co is grounded;

[0028] One end of the load resistor R is connected to the switch tube Q C The drain, output filter capacitor C o One end of the load resistor R is connected to the non-isolated DC-DC chopper converter, and the other end of the load resistor R is grounded.

[0029] A three-port single-stage non-isolated combined converter based on n units, comprising a single-stage non-isolated combined converter based on a three-port switched capacitor network and n switched capacitor units, wherein the n switched capacitor units are located between a power supply input and the single-stage non-isolated combined converter based on the three-port switched capacitor network; each switched capacitor unit comprises three switch tubes Q kA , Q kC and Q kD , a switched capacitor C fk or a resonant tank, the resonant tank consists of a resonant capacitor C rk and L rkThe resonant inductor is connected in series, k=1,2,…,n; two adjacent switched capacitor units use switched capacitor and resonant tank structures respectively, wherein: the switched capacitor unit connected to the power input side uses the resonant tank structure, and the switched capacitor unit connected to the single-stage non-isolated combined converter based on the three-port switched capacitor network uses the switched capacitor structure.

[0030] An n-unit-based three-port improved single-stage non-isolated combined converter comprises a single-stage non-isolated combined converter based on a three-port switched capacitor network and n switched capacitor units, wherein the n switched capacitor units are located between a power supply input and the single-stage non-isolated combined converter based on the three-port switched capacitor network; each switched capacitor unit comprises three switch tubes Q kA , Q kC and Q kD , a switched capacitor C fk or a resonant tank, the resonant tank consists of a resonant capacitor C rk and L rk The resonant inductor is connected in series, k=1,2,…,n; two adjacent switch capacitor units use switch capacitor and resonant tank structures respectively, wherein: the switch capacitor unit connected to the power input side and the switch capacitor unit connected to the single-stage non-isolated combined converter based on the three-port switch capacitor network both use the resonant tank structure; in the single-stage non-isolated combined converter based on the three-port switch capacitor network, the resonant tank is replaced by the switch capacitor C f .

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1) The single-stage non-isolated combined converter based on a three-port switched capacitor network is a voltage conversion circuit with a three-port switched capacitor network as the core. It uses capacitor energy storage and does not use transformer isolation in the combined converter circuit, which has the advantage of high power density.

[0033] 2) The present invention transforms a traditional two-port switched capacitor network into a three-port switched capacitor network. Through the coordinated operation of the three-port switched capacitor network and the DC-DC chopper converter, a DC voltage source and a switched capacitor network can be used to provide a DC voltage input for the DC-DC chopper converter, thereby eliminating the voltage-stabilizing capacitor between the switched capacitor network and the DC-DC chopper converter, realizing a single-stage structure combination circuit, reducing the converter volume and improving efficiency.

[0034] 3) The resonant switched capacitor network in the single-stage non-isolated combined converter based on the three-port switched capacitor network operates in the DCX mode without voltage regulation to achieve a fixed DC voltage ratio. It does not participate in voltage regulation, so that it operates at the optimal operating point to maintain the highest power conversion efficiency. This part of the circuit is responsible for processing most of the power conversion in the combined converter to improve the overall working efficiency of the combined converter.

[0035] 4) The single-stage non-isolated combined converter based on the three-port switched capacitor network uses a non-isolated DC-DC chopper converter as an auxiliary voltage conversion circuit, and adjusts the output voltage of the combined converter by changing the duty cycle, so as to achieve a wide range of continuous adjustment of the output voltage of the combined converter, and solve the problem of the small voltage regulation range of the traditional resonant switched capacitor converter. Since the DC-DC chopper converter only needs to process a small part of the power, the inductor energy storage is small and a smaller volume of inductor can be selected.

[0036] 5) When the switch capacitor in the three-port switch capacitor network of the present invention is working in the charging process, the switch capacitor and the load are connected in series, so that the power supply can supply power to the switch capacitor and the load at the same time. When the switch capacitor in the three-port switch capacitor network is working in the discharging process, the switch capacitor supplies power to the load. Compared with the circuit structure in which only the switch capacitor discharges to supply power to the load, the proposed three-port switch capacitor network has high power conversion efficiency, less energy storage required by the capacitor, smaller required capacitance, and reduced ripple on the output side.

[0037] 6) Non-isolated DC-DC converters can use DC-DC chopper converters such as Buck converters and Zeta converters. They do not require a transformer and have the advantages of simple structure and small size.

[0038] 7) All the switches in the single-stage non-isolated combined converter based on the three-port switched capacitor network can achieve soft switching, reduce switching losses and improve efficiency. By changing the action phase of the DC chopper and the switch in the three-port switched capacitor network, zero voltage switching of some switches in the switched capacitor network can be achieved. The resonant inductor can be used to achieve zero current switching of the chopper switch in the DC-DC chopper converter, reducing switching losses and improving efficiency.

[0039] 8) In order to realize the wide range voltage regulation function of the single-stage non-isolated combined converter based on the three-port switched capacitor network, Fig.16 The zero voltage soft switch shown in the invention proposes a DC-DC chopper converter PWM modulation and phase shift control method to optimize the freewheeling path of the inductor current, avoid reverse current circulation, reduce the current stress of the switch tube, and thus improve efficiency.

[0040] 9) The single-stage non-isolated combined converter based on the three-port switched capacitor network of the present invention can be combined with n switched capacitor units to obtain a multi-level circuit structure, further reducing the voltage stress of the device. Wherein, each switched capacitor unit is composed of three switch tubes and a resonant tank, or three switch tubes and a switched capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a basic step-down resonant switched capacitor converter;

[0042] Figure 2 The switching capacitor charging mode diagram of the basic buck resonant switched capacitor converter;

[0043] Figure 3 is the switch capacitor discharge mode diagram of the basic step-down resonant switch capacitor converter;

[0044] Figure 4 It is a two-stage cascaded non-isolated combined converter based on a three-port switched capacitor network;

[0045] Figure 5 It is an improved two-stage cascaded non-isolated combined converter based on a three-port switched capacitor network;

[0046] Figure 6 It is a single-stage non-isolated combined converter based on a three-port switched capacitor network;

[0047] Figure 7 The switching capacitor charging mode diagram of a single-stage non-isolated combined converter based on a three-port switching capacitor network;

[0048] Figure 8 The switching capacitor discharge mode diagram of a single-stage non-isolated combined converter based on a three-port switching capacitor network;

[0049] Fig. 9 It is a three-port single-stage non-isolated combined converter based on n units;

[0050] Fig.10 It is a three-port single-stage non-isolated combined converter based on 2 units;

[0051] Fig.11 The operating mode 1 is the three-port single-stage non-isolated combined converter based on two units;

[0052] Fig.12 It is the working mode 2 of the three-port single-stage non-isolated combined converter based on 2 units;

[0053] Fig.13 The operating mode 3 of the three-port single-stage non-isolated combined converter based on two units;

[0054] Fig.14 The operating mode 4 is the three-port single-stage non-isolated combined converter based on 2 units;

[0055] Fig.15 The operating mode 5 of the three-port single-stage non-isolated combined converter based on 2 units;

[0056] Fig.16 The current reverse circulation path diagram of the three-port single-stage non-isolated combined converter based on two units;

[0057] Fig.17 The key operating waveform diagram of the three-port single-stage non-isolated combined converter based on two units;

[0058] Fig.18 The voltage gain curve of the three-port single-stage non-isolated combined converter based on two units;

[0059] Fig.19 The structure diagram of phase-shift soft switch control of three-port single-stage non-isolated combined converter based on n units is shown;

[0060] Fig. 20 It is a three-port improved single-stage non-isolated combined converter based on n units;

[0061] Fig.21 It is a three-port improved single-stage non-isolated combined converter based on 3 units. DETAILED DESCRIPTION

[0062] The technical solution of the present invention is further described below in conjunction with the accompanying drawings, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0063] The present invention will Figure 1 The switch tube Q B Replace it with a DC-DC chopper converter, and you get Figure 6 The single-stage non-isolated combined converter based on a three-port switched capacitor network is shown in FIG. Figure 6 As shown, the non-isolated combined converter includes a three-port switch capacitor network, a non-isolated DC-DC chopper converter, an output filter capacitor C o The input end of the three-port switch capacitor network is connected to the external power supply Vin, one of the output ends is connected to the load R, and the other output end is connected to the DC-DC chopper converter. The three-port switch capacitor network includes three switch tubes Q A , Q C , Q D , a resonant tank, the resonant tank consists of a resonant inductor L r and resonant capacitor C rComposition: The switch tube Q A The drain of the external power supply V in Phase connected, switch tube Q A The source of the resonant capacitor C r One end of the resonant capacitor C is connected to a non-isolated DC-DC chopper converter; r The other end of the resonant inductor L r One end of the resonant inductor L r The other end is connected to the switch tube Q C The source of the switch tube Q D The drain of the switch tube Q C The drain of the output filter capacitor C o and one end of the load resistor R; the switch tube Q D The source of the output filter capacitor C o One end of the switch tube Q C The drain of the load resistor R is connected to the non-isolated DC-DC chopper converter, and the output filter capacitor C o The other end of the load resistor R is connected to the switch tube Q C The drain, output filter capacitor C o One end of the load resistor R is connected to the non-isolated DC-DC chopper converter, and the other end of the load resistor R is grounded. Figure 6 The non-isolated combined converter shown is a single-stage structure. By coordinating the phases of the charging and discharging modes of the three-port switched capacitor network and the chopping mode of the non-isolated DC-DC converter, no additional voltage stabilizing capacitor is required between the two circuits.

[0064] In the present invention, the resonant capacitor C in the three-port switched capacitor network r It is divided into two working modes: charging and discharging, where:

[0065] like Figure 7 As shown, when the resonant capacitor C r When charging, the power supply also supplies the resonant capacitor C r and load resistor R, resonant capacitor C r Including a complete charging process, there are voltage equations and current equations:

[0066] V in =V Cr +V o (5)

[0067] I in =I charge (6)

[0068] In the formula, I inis the average value of the combined converter input current, I charge is the resonant capacitor C r The average value of the charging current.

[0069] like Figure 8 As shown, when the resonant capacitor C r When discharging, the resonant capacitor C r The load resistor R is powered by a DC-DC chopper converter. The DC-DC chopper converter can be used to adjust the output voltage of the combined converter over a wide range, and the voltage equation and current equation are:

[0070] V o =M(D)V Cr (7)

[0071]

[0072] Where M(D) is the voltage gain function of the DC-DC chopper converter, D is the duty cycle of the chopper, and I reg is the DC-DC chopper converter output current i reg The average value of I discharge is the resonant capacitor C r The average value of the discharge current.

[0073] When the converter enters steady-state operation, the ampere-second balance principle of the capacitor shows that: Figure 7 and Figure 8 The resonant capacitor C r The average value of the charge and discharge current is equal, that is:

[0074] I in =I charge =I discharge (9)

[0075] In the formula, I in is the average value of the combined converter input current, I charge is the resonant capacitor C r The average value of the charging current, I discharge is the resonant capacitor C r The average value of the discharge current.

[0076] Will Figure 6 The single-stage non-isolated combined converter based on the three-port switched capacitor network shown in FIG. 1 is combined with n switched capacitor units to obtain Fig. 9 The three-port single-stage non-isolated combined converter based on n units is shown in Figure 2. r1 and C r is the resonant capacitor, L r1 and L r is the resonant inductor, C fnThe converter circuit is characterized by: 1) n switched capacitor units are located between the power input and the single-stage non-isolated combined converter based on the three-port switched capacitor network; 2) each switched capacitor unit contains three switch tubes Q kA , Q kC and Q kD , (k=1,2,…,n); 3) Each switched capacitor unit includes a switched capacitor or a resonant tank, and the resonant tank is composed of a resonant capacitor and a resonant inductor in series; 4) Two adjacent switched capacitor units use switched capacitor and resonant tank structures respectively. The switched capacitor unit connected to the power input side uses the resonant tank structure, and the switched capacitor unit connected to the single-stage non-isolated combined converter based on a three-port switched capacitor network uses a switched capacitor structure.

[0077] Take the circuit of two switched capacitor units as an example. Select two switched capacitor units and replace them with Buck circuits. Fig. 9 The non-isolated DC-DC converter is Fig.10 The three-port single-stage non-isolated combined converter based on two units is shown in FIG. Lr1 、i Lr2 、i Q3A and i S1 They represent the current of the corresponding branch, v Q3A and v S1 They respectively represent the drain-source voltage of the corresponding switching tube.

[0078] The three-port single-stage non-isolated combined converter based on two units has five operating modes, such as Figure 11 to Figure 15 As shown, the current in each branch in the figure flows to the output side load.

[0079] Fig.11 The current flow direction of the middle mode is shown by the dotted arrow. The power supply is to the resonant capacitor C r1 and load R charges, the switch capacitor C f Give the resonant capacitor C r2 and the load R is charged, the inductor L m The follow-up current supplies power to the load R. The currents in all branches flow to the load resistor R.

[0080] Fig.12 The current flow direction of the middle mode is shown by the dotted arrow, and the resonant capacitor C r1 To the switch capacitor C f and the load R is charged, the inductor L m The follow-up current supplies power to the load R. The currents in all branches flow to the load resistor R.

[0081] Fig.13 The current flow direction of the middle mode is shown by the dotted arrow, and the resonant capacitor C r1 To the switch capacitor Cf and the load R is charged, the resonant capacitor C r2 Through the inductor L m To charge the load R, the inductor L m The follow-up current supplies power to the load R. The currents in all branches flow to the load resistor R.

[0082] Fig.14 The current flow direction of the middle mode is shown by the dotted arrow, and the resonant capacitor C r1 To the switch capacitor C f and the load R is charged, the resonant capacitor C r2 Through the inductor L m Charge the load R. The current in all branches flows to the load resistor R.

[0083] Fig.15 The current flow direction of the middle mode is shown by the dotted arrow, and the resonant capacitor C r1 To the switch capacitor C f and the load R is charged, the resonant capacitor C r2 With the resonant inductor L r2 To the switch capacitor C f and the load R is charged, the inductor L m The follow-up current supplies power to the load R. The currents in all branches flow to the load resistor R.

[0084] If there is no phase shift between the switching signal of the three-port switched capacitor network and the DC-DC chopper converter, then Fig.10 The three-port single-stage non-isolated combined converter based on 2 units will appear Fig.16 The circulation circuit shown. Fig.16 As shown, the circulating current i of the resonant tank Lr2 From the load side back to the switch capacitor C f During charging, power flows back from the output side to the converter, reducing the output power of the converter. At the same time, the circulating current causes additional conduction losses.

[0085] The switch tube drive waveform, voltage waveform, current waveform and resonant inductor current waveform of the three-port single-stage non-isolated combined converter based on two units are shown in Figure 2. Fig.17 As shown. Among them, the chopper switch tube S in the Buck circuit of the combined converter 1 Zero current switching (ZCS) is achieved by precisely controlling the switch tube S 1 With Q 3A The phase shift angle θ of the driving signal is used to achieve Q 3A The zero voltage switch-on (ZVS) of mode 5 is also realized by using the inductor L r2 The freewheeling channel reduces the resonance slot L r2 -C r2 Loop circulation.

[0086] Fig.10 The voltage gain M expression of the three-port single-stage non-isolated combined converter based on two units is as follows:

[0087]

[0088] in:

[0089]

[0090] Where, L r2 is the resonant inductance, f s is the switching frequency, R is the load resistance, and D is the duty cycle of the Buck DC chopper circuit. The adjustment range of the duty cycle D is [0,0.5].

[0091] Fig.10 The voltage gain expression of the three-port single-stage non-isolated combined converter based on two units is shown in formula (10), and its voltage gain curve is shown in Fig.18 shown.

[0092] In order to realize the wide range voltage regulation function of the single-stage non-isolated combined converter based on the three-port switched capacitor network, Fig.17 The invention proposes a PWM modulation and phase shift control method for a DC-DC chopper converter. D The current zero-crossing signal generates a corresponding falling edge pulse signal to reset the triangle wave generator, change the phase of the PWM pulse, and thus control the phase shift angle of the three-port switch capacitor network and the DC-DC chopper converter drive signal. In order to ensure the reliable start-up of the converter, a delayed start module with phase shift control is set. The converter uses PWM modulation to start, and then the PWM modulation is phase-shifted after stable operation. The corresponding control structure is as follows Fig.19 The control structure includes an output voltage detection v o_m , switch tube current detection i QD , voltage regulator, current zero-crossing detection, delayed start, falling edge detection and PWM generator, wherein: the voltage regulator uses a PI regulator; the zero-crossing detection uses a comparator; the falling edge detection uses a D flip-flop, a NOT gate and an AND gate; the PWM generator uses a triangle wave generator and a comparator, wherein the triangle wave generator can be reset by the falling edge detection unit.

[0093] Fig. 20 The figure shows a three-port improved single-stage non-isolated combined converter based on n units. r1 and C rn is the resonant capacitor, L r1 and L rn is the resonant inductor, C fThe converter circuit is characterized by: 1) n switched capacitor units are located between the power input and the single-stage non-isolated combined converter based on the three-port switched capacitor network; 2) each switched capacitor unit contains three switch tubes Q kA , Q kC and Q kD , (k=1,2,…,n); 3) Each switched capacitor unit includes a switched capacitor or a resonant tank, and the resonant tank is composed of a resonant capacitor and a resonant inductor in series; 4) Two adjacent switched capacitor units use two structures, switched capacitor and resonant tank, respectively. The switched capacitor unit connected to the power input side and the switched capacitor unit connected to the single-stage non-isolated combined converter based on the three-port switched capacitor network both use the resonant tank structure; 5) In the improved single-stage non-isolated combined converter based on n-unit switched capacitors, the three-port switched capacitor network uses a switched capacitor C f structure.

[0094] Take the circuit of three switched capacitor units as an example. Select three switched capacitor units and replace them with Buck circuits. Fig. 20 The non-isolated DC-DC converter is Fig.21 The shown three-port improved single-stage non-isolated combined converter based on 3 units.

Claims

1. A single-stage non-isolated combined converter based on a three-port switched capacitor network, characterized in that The single-stage non-isolated combined converter includes a three-port switch capacitor network, a non-isolated DC-DC chopper converter, an output filter capacitor C o and load resistance R, where: The three-port switched capacitor network includes three switch tubes Q A , Q C , Q D , a resonant tank, the resonant tank consists of a resonant inductor L r and resonant capacitor C r composition; The switch tube Q A The drain of the external power supply V in Phase connected, switch tube Q A The source of the resonant capacitor C r One end is connected to a non-isolated DC-DC chopper converter; The resonant capacitor C r The other end of the resonant inductor L r One end of the resonant inductor L r The other end is connected to the switch tube Q C The source of the switch tube Q D The drain of is connected; The switch tube Q C The drain of the output filter capacitor C o One end of the load resistor R is connected; The switch tube Q D The source is grounded; The output filter capacitor C o One end of the switch tube Q C The drain of the output filter capacitor Co is connected to one end of the load resistor R and the non-isolated DC-DC chopper converter, and the other end of the output filter capacitor Co is grounded; One end of the load resistor R is connected to the switch tube Q C The drain, output filter capacitor C o One end of the load resistor R is connected to the non-isolated DC-DC chopper converter, and the other end of the load resistor R is grounded.

2. The single-stage non-isolated combined converter based on a three-port switched capacitor network according to claim 1, characterized in that The resonant capacitor C r It is divided into two working modes: charging and discharging, where: When the resonant capacitor C r When charging, the power supply also supplies the resonant capacitor C r and load resistor R, resonant capacitor C r Including a complete charging process, there are voltage equations and current equations: V in =V Cr +V o I in =I charge In the formula, I in is the average value of the combined converter input current, I charge is the resonant capacitor C r The average value of the charging current; When the resonant capacitor C r When discharging, the resonant capacitor C r The load resistor R is powered by a DC-DC chopper converter, and the output voltage of the combined converter is adjusted over a wide range by the DC-DC chopper converter. Then, the voltage equation and current equation are: In o =M(D)V Cr Where M(D) is the voltage gain function of the DC-DC chopper converter, D is the duty cycle of the chopper, and I reg is the DC-DC chopper converter output current i reg The average value of I discharge is the resonant capacitor C r The average value of the discharge current; When the converter enters steady-state operation, according to the ampere-second balance principle of capacitor, the resonant capacitor C r The average value of the charge and discharge current is equal, that is: I in =I charge =I discharge In the formula, I in is the average value of the combined converter input current, I charge is the resonant capacitor C r The average value of the charging current, I discharge is the resonant capacitor C r The average value of the discharge current.

3. A three-port single-stage non-isolated combined converter based on n units, characterized in that The converter comprises a single-stage non-isolated combined converter based on a three-port switched capacitor network and n switched capacitor units, wherein the n switched capacitor units are located between a power supply input and the single-stage non-isolated combined converter based on a three-port switched capacitor network; each switched capacitor unit comprises three switch tubes Q kA , Q kC and Q kD , a switched capacitor C fk or a resonant tank, the resonant tank consists of a resonant capacitor C rk and L rk The resonant inductor is connected in series, k=1,2,…,n; two adjacent switched capacitor units use switched capacitor and resonant tank structures respectively, wherein: the switched capacitor unit connected to the power input side uses the resonant tank structure, and the switched capacitor unit connected to the single-stage non-isolated combined converter based on the three-port switched capacitor network uses the switched capacitor structure.

4. A PWM modulation and phase shift control method for a three-port single-stage non-isolated combined converter based on n units as claimed in claim 3, characterized in that The method detects the switch tube Q D The current zero-crossing signal generates a corresponding falling edge pulse signal to reset the triangle wave generator and change the phase of the PWM pulse, thereby controlling the phase shift angle of the three-port switched capacitor network and the DC-DC chopper converter drive signal.

5. A three-port improved single-stage non-isolated combined converter based on n-units, characterized in that The converter comprises a single-stage non-isolated combined converter based on a three-port switched capacitor network as claimed in any one of claims 1 to 2 and n switched capacitor units, wherein the n switched capacitor units are located between a power supply input and the single-stage non-isolated combined converter based on a three-port switched capacitor network; each switched capacitor unit comprises three switch tubes Q kA , Q kC and Q kD , a switched capacitor C fk or a resonant tank, the resonant tank consists of a resonant capacitor C rk and L rk The resonant inductor is connected in series, k=1,2,…,n; two adjacent switch capacitor units use switch capacitor and resonant tank structures respectively, wherein: the switch capacitor unit connected to the power input side and the switch capacitor unit connected to the single-stage non-isolated combined converter based on the three-port switch capacitor network both use the resonant tank structure; in the single-stage non-isolated combined converter based on the three-port switch capacitor network, the resonant tank is replaced by the switch capacitor C f .

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