A single-stage non-isolated combined converter based on a three-port switched capacitor network

Abstract

The application discloses a single-stage non-isolated combined converter based on a three-port switched capacitor network, which comprises a three-port switched capacitor network, a non-isolated DC-DC chopper converter, an output filter capacitor C o and a load resistor R. The application changes a conventional two-port switched capacitor network into a three-port switched capacitor network, and through the cooperative operation of the three-port switched capacitor network and the DC-DC chopper converter, a DC voltage source and the switched capacitor network can be used to provide a DC voltage input for the DC-DC chopper converter, and then the voltage stabilizing capacitor between the switched capacitor network and the DC-DC chopper converter is cancelled, the combined circuit with a single-stage structure is realized, the volume 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, a multi-level circuit structure is obtained, and the voltage stress of the device is further reduced.

Description

Technical Field

[0001] This invention relates to a combined converter based on resonant switched capacitors, and more specifically to a single-stage non-isolated combined converter based on a three-port switched capacitor network. Background Technology

[0002] The energy density of a capacitor is 10 to 1000 times that of an inductor. Therefore, switched-capacitor converters, which use capacitors as the main energy storage element, have a higher power density than switched-inductor converters that use inductors for energy storage. However, switched-capacitor converters suffer from inrush current and hard switching of the switching transistor during capacitor charging and discharging. To address these issues, a resonant switched-capacitor converter is constructed by connecting a hollow inductor or stray inductance from the circuit in series with the switched capacitor branch as a resonant inductor. This eliminates the inrush current and also offers the advantages of soft switching of the switching transistor, low electromagnetic noise, and high power density.

[0003] When used as a DC-DC transformer (DCX), the resonant switched-capacitor converter exhibits very high efficiency. For example, the slot-slot converter based on the resonant switched-capacitor network is widely used in low-voltage DC-DC conversion applications such as data center power supplies due to its advantages of consistent switching transistor voltage stress, modularity, and easy expansion. However, when used as a DC-DC transformer, the input and output voltage ratio of the resonant switched-capacitor converter is fixed and dependent on the circuit structure, making it non-adjustable.

[0004] Figure 1 For a basic buck resonant switched capacitor converter, the input power supply 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 switching transistors Q. A Q B Q C Q D A resonant slot (composed of resonant inductor L) r and resonant capacitor C r (Composition). To achieve higher power conversion efficiency, the resonant switched capacitor converter needs to operate in a fully resonant mode, that is, the resonant capacitance C in each switching cycle... r Both involve a complete charging process and a complete discharging process.

[0005] 1) such as Figure 2 As shown, when the resonant capacitor C r During charging, the power supply simultaneously supplies power to the resonant capacitor C. r Powered by a load resistor R, the voltage equation is:

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

[0007] In the formula, V Cr For the resonant capacitor C r voltage v Cr The average value.

[0008] 2) such as Figure 3 As shown, when the resonant capacitor C r During discharge, the resonant capacitor C r When power is supplied to the load resistor R, the voltage equation is:

[0009] V o =V Cr (2)

[0010] Based on the voltage relationship during the charging and discharging process of the resonant capacitor, it can be concluded that the input voltage of the basic buck 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] Based on the ampere-second balance principle of capacitors, when the basic buck resonant switched capacitor converter enters steady-state operation, the resonant capacitor C... r The average values ​​of the charging and discharging currents are equal, meaning the average output current is twice the average input current.

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

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

[0015] While continuous voltage regulation of resonant switched-capacitor converters can be achieved by changing the operating frequency, their voltage regulation capability is poor, and the regulation range is greatly affected by the load. Especially under light load conditions, the switching frequency is very high, limiting their application in many scenarios. Furthermore, during voltage regulation, the resonant slot circuit of the converter exhibits a very large circulating current, resulting in significant current conduction losses and a substantial reduction in the converter's voltage regulation efficiency.

[0016] In contrast, DC chopper converters have the advantages of a wide voltage regulation range and less susceptibility to load conditions, but they require a large inductor as the main energy storage element. Furthermore, the switching transistors of DC chopper converters generally operate in hard switching mode, resulting in higher switching losses, which is not conducive to the miniaturization and high-frequency operation of equipment.

[0017] In response, references 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 2 (S. Han, Y. Wang, Z. Xie, Y. Guan, J. MAlonso 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, an adjustable Buck converter, and a resonant switched capacitor converter. The front-end circuit uses the three-port series switched capacitor network to distribute the input voltage to two series-connected switched capacitors in a certain proportion. One of the switched capacitors achieves a fixed step-down conversion through the subsequent resonant switched capacitor converter, while the other switched capacitor adjusts the output voltage through the subsequent 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 the small voltage regulation range of traditional resonant switched capacitor converters. However, the three-port series switched capacitor network of the above combined converter requires two large capacitors to provide stable DC voltage support for the subsequent step-down circuit, and the switching transistor of the subsequent Buck DC chopper circuit is a hard switch. Furthermore, the power supply on the input side cannot supply power to the load while charging the front-end switched capacitors; the front-end circuit can only supply power to the load during the discharge of the switched capacitors, resulting in low energy conversion efficiency and large output ripple for the front-end three-port series switched capacitor network.

[0018] Because the front-stage three-port series switched capacitor network in the two-stage combined converters of References 1 and 2 must operate synchronously with the drive signal of the rear-stage Buck DC chopper circuit, the voltage regulation range of the rear-stage Buck DC chopper circuit is limited. To address this, as... 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 subsequent Buck converter and the resonant switched-capacitor converter are interchanged, 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 Buck converter, and a resonant switched capacitor converter. Figure 5 In the converter shown, the operating states of the front-stage three-port series switched capacitor network and the rear-stage Buck DC chopper circuit are independent, thus allowing the rear-stage Buck DC chopper circuit to operate over a wider voltage regulation range. However, the switching transistors in the combined converter are all hard switches, resulting in high switching losses. It suffers from the same problem as the two-stage combined converters in References 1 and 2: the input power supply cannot supply power to the load while charging the front-stage switched capacitors; the front-stage circuit can only supply power to the load during the discharge of the switched capacitors. This leads to low energy conversion efficiency of the front-stage series switched capacitor network and large output ripple. Summary of the Invention

[0019] The purpose of this invention is to provide a single-stage non-isolated combined converter based on a three-port switched capacitor network. This combined converter fully leverages the advantages of high power density and high efficiency in non-voltage-regulating mode of the resonant switched capacitor converter. By combining the resonant switched capacitor network with a DC-DC chopper converter through partial power processing technology, it not only possesses the advantages of high power density and high efficiency in non-voltage-regulating mode of the resonant switched capacitor network, but also the advantages of wide voltage regulation range of the DC-DC chopper converter, as well as the advantages of soft switching.

[0020] The objective of this invention is achieved through the following technical solution:

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

[0022] The three-port switched capacitor network includes three switching transistors Q. A Q C Q DA resonant slot, the resonant slot being formed by a resonant inductor L r and resonant capacitor C r composition;

[0023] The switching transistor Q A The drain of the external power supply V in Connected, switching transistor Q A The source terminals are respectively connected to 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 is connected to the resonant inductor L r One end is connected to the resonant inductor L. r The other end is connected to the switching transistor Q. C The source and switch Q D The drains are connected;

[0025] The switching transistor Q C The drain of each capacitor is connected to the output filter capacitor C. o One end of the resistor is connected to one end of the load resistor R;

[0026] The switching transistor Q D The source is grounded;

[0027] The output filter capacitor C o One end is connected to the switching transistor Q. C The drain of the capacitor 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.

[0028] One end of the load resistor R is connected to the switching transistor Q. C The drain and output filter capacitor C o One end of the resistor is connected to a 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 includes 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 the power input and the single-stage non-isolated combined converter based on the three-port switched capacitor network; each switched capacitor unit includes three switching transistors Q. kA Q kC and Q kD A switched capacitor C fk Or a resonant tank, the resonant tank consisting of a resonant capacitor C rk and L rkThe resonant inductors are connected in series, k = 1, 2, ..., n; two adjacent switched capacitor units use both switched capacitor and resonant slot structures respectively. Specifically, the switched capacitor unit connected to the power input side uses the resonant slot 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 improved three-port single-stage non-isolated combined converter based on n units includes 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 the power input and the single-stage non-isolated combined converter based on the three-port switched capacitor network; each switched capacitor unit includes three switching transistors Q. kA Q kC and Q kD A switched capacitor C fk Or a resonant tank, the resonant tank consisting of a resonant capacitor C rk and L rk The resonant inductors are connected in series, k = 1, 2, ..., n; adjacent switched capacitor units use both switched capacitor and resonant slot structures respectively, wherein: 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 slot structure; in the single-stage non-isolated combined converter based on the three-port switched capacitor network, the resonant slot is replaced by a switched 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 its core. It utilizes capacitor energy storage and does not use transformer isolation in the combined converter circuit, which has the advantage of high power density.

[0033] 2) This invention transforms the 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, the DC voltage input of the DC-DC chopper converter can be provided by the DC voltage source and the switched capacitor network. This eliminates the need for the voltage regulator capacitor between the switched capacitor network and the DC-DC chopper converter, realizing a single-stage combined circuit, reducing the size of the converter and improving efficiency.

[0034] 3) In the single-stage non-isolated combined converter based on a three-port switched capacitor network, the resonant switched capacitor network operates in the DCX mode without voltage regulation, achieving a fixed DC voltage ratio and not participating 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 handling most of the power conversion in the combined converter, so as to improve the overall working efficiency of the combined converter.

[0035] 4) The single-stage non-isolated combined converter based on a three-port switched capacitor network uses a non-isolated DC-DC chopper converter as an auxiliary voltage conversion circuit. By changing the duty cycle, the output voltage of the combined converter is adjusted, achieving a wide range of continuously adjustable output voltage, thus solving the problem of small voltage regulation range in traditional resonant switched capacitor converters. Since the DC-DC chopper converter only needs to handle a small portion of the power, less inductor energy storage is required, allowing for the use of smaller inductors.

[0036] 5) In the three-port switched capacitor network of this invention, when the switched capacitor is charging, the power supply can simultaneously supply power to both the switched capacitor and the load by connecting the switched capacitor and the load in series. When the switched capacitor is discharging, it supplies power to the load. Compared with a circuit structure that only supplies power to the load by discharging the switched capacitor, the proposed three-port switched capacitor network has higher energy conversion efficiency, requires less energy storage, requires a smaller capacitor, and reduces output ripple.

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

[0038] 7) In a single-stage non-isolated combined converter based on a three-port switched capacitor network, all switching transistors can achieve soft switching, reducing switching losses and improving efficiency. By changing the operating phase of the DC chopper and the switching transistors in the three-port switched capacitor network, zero-voltage turn-on of some switching transistors in the switched capacitor network can be achieved. Using a resonant inductor, zero-current turn-on of the chopper switching transistors in the DC-DC chopper converter can be achieved, reducing switching losses and improving efficiency.

[0039] 8) To achieve wide-range voltage regulation of a single-stage non-isolated combined converter based on a three-port switched capacitor network, and simultaneously realize... Figure 16 The zero-voltage soft switch shown in this invention proposes a PWM modulation and phase-shift control method for DC-DC chopper converters, which optimizes the freewheeling path of the inductor current, avoids reverse current circulation, reduces the current stress on the switching transistor, and thus improves efficiency.

[0040] 9) The single-stage non-isolated combined converter based on a three-port switched capacitor network of this invention can be combined with n switched capacitor units to obtain a multi-level circuit structure, further reducing the voltage stress on the devices. Each switched capacitor unit consists of three switching transistors and one resonant slot, or three switching transistors and one switched capacitor. Attached Figure Description

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

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

[0043] Figure 3 The switched capacitor discharge mode diagram of a basic buck resonant switched capacitor converter;

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

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

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

[0047] Figure 7 The switched capacitor charging mode diagram is shown for a single-stage non-isolated combined converter based on a three-port switched capacitor network.

[0048] Figure 8 The switched capacitor discharge mode diagram is shown for a single-stage non-isolated combined converter based on a three-port switched capacitor network.

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

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

[0051] Figure 11 This represents the operating mode 1 of a three-port single-stage non-isolated combined converter based on two units.

[0052] Figure 12 This represents the second operating mode of a three-port single-stage non-isolated combined converter based on two units.

[0053] Figure 13 This represents the operating mode 3 of a three-port single-stage non-isolated combined converter based on two units.

[0054] Figure 14 This represents the operating mode 4 of a three-port single-stage non-isolated combined converter based on two units.

[0055] Figure 15 This represents the operating mode 5 of a three-port single-stage non-isolated combined converter based on two units.

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

[0057] Figure 17 The key operating waveforms of a three-port single-stage non-isolated combinational converter based on two units are shown.

[0058] Figure 18 The voltage gain curve is shown for a three-port single-stage non-isolated combined converter based on two units.

[0059] Figure 19 The diagram shows the phase-shift soft-switching control structure of a three-port single-stage non-isolated combined converter based on n units.

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

[0061] Figure 21 It is a three-port improved single-stage non-isolated combinational converter based on 3 units. Detailed Implementation

[0062] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0063] This invention will Figure 1 The switching transistor Q in B Replacing it with a DC-DC chopper converter yields... Figure 6 The diagram shows a single-stage non-isolated combined converter based on a three-port switched capacitor network. (Example:) Figure 6 As shown, the non-isolated combined converter includes a three-port switched capacitor network, a non-isolated DC-DC chopper converter, and an output filter capacitor C. o The three-port switched capacitor network has a load resistor R, an input terminal connected to an external power supply Vin, one output terminal connected to the load R, and the other output terminal connected to a DC-DC chopper converter. The three-port switched capacitor network includes three switching transistors Q. A Q C Q D A resonant slot, the resonant slot being formed by a resonant inductor L r and resonant capacitor C rComposition; the switching transistor Q A The drain of the external power supply V in Connected, switching transistor Q A The source terminals are respectively connected to 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 is connected to the resonant inductor L r One end is connected to the resonant inductor L. r The other end is connected to the switching transistor Q. C The source and switch Q D The drains of the transistors are connected; the switching transistor Q... C The drain of each capacitor is connected to the output filter capacitor C. o One end of the switch Q is connected to one end of the load resistor R; the switch Q is connected to one end of the load resistor R. D The source is grounded; the output filter capacitor C o One end is connected to the switching transistor Q. C The drain, one end of the load resistor R, and the output filter capacitor C are connected together. o The other end is grounded; one end of the load resistor R is connected to the switching transistor Q. C The drain and output filter capacitor C o One end of the resistor is connected to a 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 phase of the charging and discharging mode of the three-port switched capacitor network with the chopping mode of the non-isolated DC-DC converter, no additional voltage regulator capacitor is required between the two circuits.

[0064] In this invention, the resonant capacitor C in the three-port switched capacitor network r It has two operating modes: charging and discharging.

[0065] like Figure 7 As shown, when the resonant capacitor C r During charging, the power supply simultaneously supplies power to the resonant capacitor C. r Powered by load resistor R, resonant capacitor C r If a complete charging process is included, then 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 inI is the average value of the input current of the combined converter. charge For the resonant capacitor C r The average value of the charging current.

[0069] like Figure 8 As shown, when the resonant capacitor C r During discharge, the resonant capacitor C r The load resistor R is powered by a DC-DC chopper converter. The DC-DC chopper converter enables wide-range adjustment of the output voltage of the combined converter, resulting in the voltage and current equations:

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

[0071]

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

[0073] Once the converter enters steady-state operation, the ampere-second balance principle of the capacitor can be used to determine... Figure 7 and Figure 8 Resonant capacitor C r The average charging and discharging currents are equal, that is:

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

[0075] In the formula, I in I is the average value of the input current of the combined converter. charge For the resonant capacitor C r The average value of the charging current, I discharge For 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 a three-port switched capacitor network shown is combined with n switched capacitor units to obtain... Figure 9 The diagram shows a three-port single-stage non-isolated combinational converter based on an n-cell unit, C. r1 and C r For resonant capacitor, L r1 and L r For resonant inductance, C fnThe converter circuit uses switched capacitors. Its characteristics are: 1) n switched capacitor units are located between the power input and a single-stage non-isolated combined converter based on a three-port switched capacitor network; 2) each switched capacitor unit contains three switching transistors Q. kA Q kC and Q kD , (k=1,2,…,n); 3) Each switched capacitor unit contains a switched capacitor or a resonant slot, the resonant slot is composed of a resonant capacitor and a resonant inductor connected in series; 4) Two adjacent switched capacitor units use both switched capacitor and resonant slot structures respectively. The switched capacitor unit connected to the power input side uses the resonant slot 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.

[0077] Taking a circuit with two switched capacitor units as an example, two switched capacitor units are selected, and a Buck circuit is used instead. Figure 9 A non-isolated DC-DC converter is obtained. Figure 10 The diagram shows a three-port single-stage non-isolated combinational converter based on a 2-unit architecture. In the figure, i... Lr1 i Lr2 i Q3A and i S1 These represent the currents in the corresponding branches, v and v. Q3A and v S1 These represent the drain-source voltages of the corresponding switching transistors.

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

[0079] Figure 11 The current flow direction in the middle mode is shown by the dashed arrow. The power supply supplies the resonant capacitor C. r1 Charging the load R, switching capacitor C f Give the resonant capacitor C r2 And the load R is charged, and the inductor L m The current continues to supply power to the load R. The current in all branches flows to the load resistor R.

[0080] Figure 12 The current flow direction in the middle mode is shown by the dashed arrow, and the resonant capacitance C... r1 To the switched capacitor C f And the load R is charged, and the inductor L m The current continues to supply power to the load R. The current in all branches flows to the load resistor R.

[0081] Figure 13 The current flow direction in the middle mode is shown by the dashed arrow, and the resonant capacitance C... r1 To the switched capacitor Cf The load R is charged, and the resonant capacitor C r2 Through inductor L m Charging load R, inductor L m The current continues to supply power to the load R. The current in all branches flows to the load resistor R.

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

[0083] Figure 15 The current flow direction in the middle mode is shown by the dashed arrow, and the resonant capacitance C... r1 To the switched capacitor C f The load R is charged, and the resonant capacitor C r2 With resonant inductor L r2 To the switched capacitor C f And the load R is charged, and the inductor L m The current continues to supply power to the load R. The current in all branches flows to the load resistor R.

[0084] If there is no phase shift between the three-port switched capacitor network and the switching signal of the DC-DC chopper converter, then Figure 10 The three-port single-stage non-isolated combinational converter based on two units shown will exhibit... Figure 16 The circulating loop shown. Figure 16 As shown, the circulating current i of the resonant tank Lr2 The return flow from the load side is supplied to the switched capacitor C. f During charging, power flows back to the converter from the output side, reducing the converter's output power. At the same time, this circulating current causes additional conduction losses.

[0085] The switching transistor drive waveform, voltage waveform, current waveform, and resonant inductor current waveform of a two-unit three-port single-stage non-isolated combined converter are shown below. Figure 17 As shown. In the Buck circuit of the combined converter, the chopper switch S1 achieves zero-current turn-on (ZCS). This is achieved by precisely controlling the relationship between switch S1 and Q. 3A The phase shift angle θ of the drive signal realizes Q 3A Zero-voltage turn-on (ZVS), while utilizing the inductor L in mode 5. r2 The freewheeling channel reduces the resonant slot L r2 -C r2 The circulating current in the loop.

[0086] Figure 10The voltage gain M of the three-port single-stage non-isolated combined converter based on a 2-cell unit is expressed as follows:

[0087]

[0088] in:

[0089]

[0090] In the formula, L r2 For resonant inductance, f s R is the switching frequency, R is the load resistance, and D is the duty cycle of the Buck DC chopper circuit. The duty cycle D can be adjusted within the range of [0, 0.5].

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

[0092] To achieve wide-range voltage regulation in a single-stage non-isolated combined converter based on a three-port switched capacitor network, and simultaneously realize... Figure 17 The zero-voltage soft-switching shown in this invention presents a PWM modulation and phase-shift control method for a DC-DC chopper converter. This method involves detecting the switching transistor Q... D The zero-crossing current signal generates a corresponding falling edge pulse signal to reset the triangular wave generator, changing the phase of the PWM pulse, thereby controlling the phase shift angle of the drive signal of the three-port switched capacitor network and the DC-DC chopper converter. To ensure reliable converter startup, a phase-shift control delay startup module is set up. The converter uses PWM modulation for startup, and the PWM modulation is phase-shifted after stable operation. The corresponding control structure is as follows: Figure 19 As shown. The control structure includes an output voltage detection v o_m Switch current detection i QD The system includes a voltage regulator, a zero-crossing current detector, a delayed start-up mechanism, a falling edge detector, and a PWM generator. Specifically, the voltage regulator uses a PI regulator; the zero-crossing detection uses a comparator; the falling edge detection uses a D flip-flop, NOT gate, and AND gate; and the PWM generator uses a triangular wave generator and a comparator, wherein the triangular wave generator can be reset by the falling edge detection unit.

[0093] Figure 20 The diagram shows an improved three-port single-stage non-isolated combinational converter based on n units. (C) r1 and C rn For resonant capacitor, L r1 and L rn For resonant inductance, C fThe converter circuit uses switched capacitors. Its characteristics are: 1) n switched capacitor units are located between the power input and a single-stage non-isolated combined converter based on a three-port switched capacitor network; 2) each switched capacitor unit contains three switching transistors Q. kA Q kC and Q kD , (k=1,2,…,n); 3) Each switched capacitor unit contains either a switched capacitor or a resonant slot, the resonant slot being composed of a resonant capacitor and a resonant inductor connected in series; 4) Adjacent switched capacitor units use both switched capacitor and resonant slot structures 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 slot structure; 5) In the improved single-stage non-isolated combined converter based on n-unit switched capacitors, the three-port switched capacitor network uses switched capacitor C f structure.

[0094] Take a circuit with three switched capacitor units as an example. Three switched capacitor units are selected, and a Buck circuit is used instead. Figure 20 A non-isolated DC-DC converter is obtained. Figure 21 The diagram shows a three-port improved single-stage non-isolated combinational converter based on three units.

Claims

1. A single-stage non-isolated hybrid converter based on a three-port switched-capacitor network, characterized in that The single-stage non-isolated combined converter comprises a three-port switched capacitor network, a non-isolated DC-DC chopper converter, and an output filter capacitor C o and a load resistor R, wherein: The three-port switched capacitor network comprises three switching tubes Q A , Q C , Q D , a resonant tank, the resonant tank is composed of resonant inductance L r and resonant capacitance C r ; The drain of the switch tube Q A is connected with an external power supply V in , the source of the switch tube Q A is respectively connected with one end of the resonance capacitor C r and the non-isolated DC-DC chopper converter. The other end of the resonant capacitor C r is connected with one end of the resonant inductor L r , and the other end of the resonant inductor L r is respectively connected with the source of the switch tube Q C and the drain of the switch tube Q D ; The drain of the switch tube Q C is connected with one end of the output filter capacitor C o and one end of the load resistor R respectively. The source of the switch tube Q D is grounded. The output filter capacitor C o One end is connected to the switching transistor Q. C The drain of the capacitor 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 with the drain of the switch tube Q C , one end of the output filter capacitor C o , and the non-isolated DC-DC chopper converter, respectively, and the other end of the load resistor R is grounded.

2. The single-stage non-isolated combined converter based on three-port switched- capacitor network of claim 1, wherein The resonant capacitance C r The two working modes are charging and discharging, wherein: When the resonant capacitor C r is charged, the power supply simultaneously supplies the resonant capacitor C r and the load resistor R, the resonant capacitor C r contains a complete charging process, then there are voltage and current equations: where I in is the average value of the input current of the combination transformer, I charge is the resonant capacitance C r is the average value of the charging current; When the resonance capacitor C r When discharging, the resonance capacitor C r The load resistor R is powered by the DC-DC chopper converter, and the wide-range regulation of the output voltage of the combined converter is realized by the DC-DC chopper converter, and then there are voltage equation and current equation: where M(D) is the voltage gain function of the DC-DC chopper converter, D is the duty cycle of the chopping, I reg is the average value of the DC-DC chopper converter output current i reg discharge is the average value of the resonant capacitor C r discharge current;​ When the converter enters steady state operation, by the ampere-second balance principle of the capacitor, the average values of the charge and discharge currents of the resonant capacitor C r are equal, that is: where I in is the average value of the input current of the combination transformer charge is the resonant capacitance C r is the average value of the charging current discharge is the resonant capacitance C r is the average value of the discharging current 3. An n-cell based three-port single-stage non-isolated hybrid converter characterized by The converter comprises the single-stage non-isolated combined converter based on the three-port switched capacitor network and n switched capacitor units according to any one of claims 1-2, the n switched capacitor units being located between the power input and the single-stage non-isolated combined converter based on the three-port switched capacitor network; each switched capacitor unit comprises three switching tubes Q kA , Q kC and Q kD , a switched capacitor C fk or a resonant tank composed of a resonant capacitor C rk and a resonant inductor L rk in series, k = 1, 2, …, n; two adjacent switched capacitor units use two structures of switched capacitor and resonant tank 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. The PWM modulation and phase-shifted control method of the n-cell based three-port single-stage non-isolated hybrid converter of claim 3, characterized in that The method resets the triangular wave generator by detecting the current zero-crossing signal of the switch tube Q D , generates a corresponding falling edge pulse signal, changes the phase of the PWM pulse, thereby controls the phase shift angle of the three-port switched capacitor network and the DC-DC chopper converter driving signal.

5. An n-cell based three-port modified single-stage non-isolated hybrid converter characterized by The converter comprises the single-stage non-isolated combined converter based on the three-port switched capacitor network and n switched capacitor units according to any one of claims 1-2, the n switched capacitor units being located between the power input and the single-stage non-isolated combined converter based on the three-port switched capacitor network; each switched capacitor unit comprises three switching tubes Q kA , Q kC , and Q kD , a switched capacitor C fk , or a resonant tank composed of a resonant capacitor C rk and a resonant inductor L rk in series, k = 1, 2, …, n; two adjacent switched capacitor units use both the switched capacitor and the resonant tank structures, wherein: 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; in the single-stage non-isolated combined converter based on the three-port switched capacitor network, the resonant tank is replaced by a switched capacitor C f .

Images