CN111682753B

CN111682753B - Hybrid power converter and control method thereof

Info

Publication number: CN111682753B
Application number: CN202010516144.8A
Authority: CN
Inventors: 黎坚
Original assignee: Hangzhou Ainuo Semiconductor Co ltd
Current assignee: Hangzhou Ainuo Semiconductor Co ltd
Priority date: 2020-06-09
Filing date: 2020-06-09
Publication date: 2021-10-26
Anticipated expiration: 2040-06-09
Also published as: CN111682753A

Abstract

The application discloses a hybrid power converter and a control method thereof. The hybrid power converter includes: the first group of switching elements, the inductor and the switched capacitor network are sequentially connected between the first end and the second end of the hybrid power converter, and the first group of switching elements are controlled to be switched on and off according to the first group of control signals, so that the connection state of the first end of the hybrid power converter is periodically changed; the switched capacitor network includes a second set of switching elements and a plurality of capacitors, and controls the second set of switching elements to turn on and off according to a second set of control signals to periodically change the inductance and the plurality of capacitor charging and discharging states, the hybrid power converter adjusting duty cycles of the first set of control signals and the second set of control signals, respectively, to convert the input voltage to a desired output voltage. The hybrid power converter can improve the output voltage regulation capability of the circuit, realize the miniaturization of the circuit and improve the conversion efficiency of the circuit.

Description

Hybrid power converter and control method thereof

Technical Field

The present invention relates to a power converter, and more particularly, to a hybrid power converter having both an inductor and a capacitor as energy storage elements and a control method thereof.

Background

A power converter is a power module that converts an input voltage waveform to a desired output voltage or output current. The power converter comprises a switching element and an energy storage element, wherein the switching element is periodically switched on and off according to a control signal, and the energy storage element correspondingly stores electric energy and releases the electric energy, so that an output voltage signal is provided at the output end of the power converter.

In a power converter using an inductor as an energy storage element, a feedback loop is used to adjust the duty cycle of a control signal, so that a substantially constant output voltage or output current can be obtained. In a power converter having a capacitor as an energy storage element, the on time and off time of a switching element are larger than a charging time constant and a discharging time constant, and an output voltage in a fixed ratio to an input voltage is obtained in a steady state.

Fig. 1a and 1b show a schematic circuit diagram of a switched capacitor network power converter and an operating waveform diagram of a control signal, respectively, according to the prior art. In the power converter, the switching elements Q1 and Q2 are alternately turned on and off, the capacitor C1 is periodically charged and discharged to transmit electric energy from the input terminal to the output terminal, and the output capacitor Co is connected to the output terminal to filter out ripples to obtain a stable output voltage, for example, 1: 1, fixed ratio output voltage. Compared with a power converter adopting an inductor, the power converter adopting the switched capacitor topology has the advantages of small capacitor size, high circuit conversion efficiency and power density and low voltage stress of a switching element, but has the defects of difficulty in flexibly adjusting output voltage, large number of switching elements and difficulty in designing a control circuit.

Therefore, there is a need to develop a new hybrid power converter circuit that combines the advantages of the conventional inductor and capacitor power converter to provide a power solution with high conversion efficiency and high power density.

Disclosure of Invention

In view of the above, the present invention provides a hybrid power converter and a control method thereof, in which an inductor and a capacitor are used as energy storage elements, and a connection path of a plurality of capacitors is periodically changed by controlling a first group of switching elements and switching elements in a switched capacitor network respectively, so that the inductor and the plurality of capacitors are switched between charging and discharging states to obtain an output voltage adjustable within a predetermined voltage range.

In one aspect the present invention provides a hybrid power converter comprising:

a first group of switching elements connected to a first terminal of the hybrid power converter, the first group of switching elements being controlled to be turned on and off according to a first group of control signals, thereby periodically changing a connection state of the first terminal;

an inductor connected to one of connection nodes between the first group of switching elements;

a switched capacitor network connected between the inductor and the second terminal of the hybrid power converter, including a second group of switching elements and a plurality of capacitors, and controlling the second group of switching elements to be turned on and off according to a second group of control signals, so as to periodically change the connection paths of the plurality of capacitors, thereby charging and discharging the inductor and the plurality of capacitors,

wherein the hybrid power converter adjusts duty cycles of the first and second sets of control signals, respectively, to convert the input voltage to a desired output voltage.

Preferably, the second group of switching elements of the aforementioned switched capacitor network comprises:

a first type of switching element comprising a first switching element and a second switching element connected in series between a second terminal of the power converter and ground, the first switching element and the second switching element forming a second node;

a second-type switching element including a fourth switching element and a third switching element connected in series between a second terminal of the power converter and ground, the fourth switching element and the third switching element forming a third node; and

a third type of switching element connected in series between the inductor and the second terminal of the power converter, the third type of switching element and the inductor and each other forming a fourth set of nodes,

the first ends of the capacitors are sequentially connected to corresponding nodes in the fourth group of nodes, and the second ends of the capacitors are alternately connected to one of the second nodes and the fourth nodes.

Preferably, the first group of switching elements includes a fifth switching element and a sixth switching element, which are connected in series between the first terminal of the power converter and one of connection nodes formed between the aforementioned switching elements of the third type.

Preferably, the number of the aforementioned third type switching elements is the same as the number of the aforementioned plurality of capacitors.

Preferably, the aforementioned first set of control signals comprises a first control signal and a second control signal, which are periodic signals comprising an on-time and an off-time, respectively, and are complementary to each other;

the aforementioned second set of control signals includes a third control signal and a fourth control signal that are periodic signals including an on time and an off time, respectively, and that are complementary to each other.

Preferably, the second control signal and the third control signal have the same period, and the third control signal is triggered by delaying from the second control signal by a period of time.

Preferably, the control terminal of the fifth switching element receives the first control signal, and the control terminal of the sixth switching element receives the second control signal;

the control terminals of the odd-numbered ones of the first, third and third types of switching elements receive the third control signal, and the control terminals of the even-numbered ones of the second, fourth and third types of switching elements receive the fourth control signal.

Preferably, the number of the second group of capacitors in the switched capacitor network is selected to obtain a predetermined voltage range, and the duty ratio of the first control signal and the second control signal is adjusted to obtain a desired output voltage in the predetermined voltage range.

Preferably, a first terminal of the hybrid power converter is provided as an input terminal to receive an input voltage, a second terminal of the power converter is provided as an output terminal to provide the output voltage, and the hybrid power converter operates as a buck converter.

Preferably, the output voltage in steady state during successive switching cycles of the hybrid power converter is as follows,

Vo＝Vi*D1/{N+1-D2-[N*(t4-t3)+(N-1)*(t5-t4)]/T} (14)

where Vo denotes an output voltage, Vi denotes an input voltage, D1 denotes a duty ratio of the first control signal, D2 denotes a duty ratio of the third control signal, N denotes the number of the plurality of capacitors, and N is a natural number equal to or greater than 2.

Preferably, the hybrid power converter further comprises: an output capacitor connected between the second terminal of the power converter and ground.

Preferably, the second terminal of the hybrid power converter is used as an input terminal to receive the input voltage, the first terminal of the power converter is used as an output terminal to provide the output voltage, and the hybrid power converter operates as a boost converter.

Vo＝Vi*(N-D2+D1)/D1 (15)

Preferably, the hybrid power converter further comprises: an output capacitor connected between the first terminal of the power converter and ground.

In another aspect, the present invention provides a method for controlling a hybrid power converter, the power converter including a first set of switching elements, an inductor, and a switched capacitor network connected in sequence between a first terminal and a second terminal, the switched capacitor network including a plurality of switching elements and a plurality of capacitors, the method comprising:

selecting the number of the plurality of capacitors in the switched capacitor network to obtain a predetermined voltage range;

controlling the on and off of the first group of switching elements by using a periodic first group of control signals so as to change the connection state of the first end of the power converter;

the on and off of the plurality of switch elements in the switched capacitor network are controlled by a second group of periodic control signals to change the connection paths of the plurality of capacitors, so that the inductor and the plurality of capacitors are charged and discharged; and

and respectively adjusting the duty ratios of the first group of control signals and the second group of control signals to obtain the expected output voltage in the preset voltage range.

Preferably, the plurality of capacitors are sequentially connected to nodes of adjacent switching elements among the plurality of switching elements, and include a first group of capacitors having odd ordinal numbers and a second group of capacitors having even ordinal numbers.

Preferably, the step of controlling the on and off of the first group of switching elements by using a periodic first group of control signals comprises:

controlling a first end of the power converter and the inductor to be in a conducting state in a first time period and a second time period of each switching cycle;

and controlling the first end of the power converter and the inductor to be in a cut-off state in the third time period and the fourth time period of each switching cycle.

Preferably, the step of controlling the on and off of the plurality of switching elements in the switched capacitor network with a periodic second set of control signals comprises:

during the first time period and the fourth time period of each switching cycle, connecting the first end of the first capacitor of the first group of capacitors to the second end of the inductor, connecting the first ends of the rest capacitors of the first group of capacitors to ground, connecting the second ends of the first group of capacitors to the second end of the power converter, and connecting the first ends of the second group of capacitors to the second end of the power converter, and connecting the second ends of the second group of capacitors to ground;

and in the second time period and the third time period of each switching cycle, connecting the first end of the first capacitor of the first group of capacitors to the second end of the inductor, connecting the first ends of the rest capacitors in the first group of capacitors to the second end of the power converter, connecting the second ends of the first group of capacitors to the ground, and connecting the first ends of the second group of capacitors to the ground, and connecting the second ends of the second group of capacitors to the second end of the power converter.

Preferably, the first ends of the rest capacitors in the first group of capacitors are connected to the second end of the power converter or the ground through a corresponding one of the second group of capacitors, and the first ends of the second group of capacitors are connected to the second end of the power converter or the ground through a corresponding one of the first group of capacitors.

The invention has the beneficial effects that: according to the hybrid power converter and the control method thereof provided by the invention, the output voltage Vo proportional to the input voltage Vi can be provided, and the duty ratios of the first group of control signals and the second group of control signals are respectively changed to obtain the expected output voltage in the preset voltage range. Therefore, the hybrid power converter can improve the output voltage regulation capability (regulation) of the circuit and obtain the expected conversion ratio.

According to the hybrid power converter provided by the invention, the first group of switching elements are connected to the input end of the power converter, the switched capacitor network is connected to the output end of the power converter, and the inductor is connected in series between the first group of switching elements and the switched capacitor network. Compared with the traditional power converter adopting the inductor, the volt-second product applied to the inductor is greatly reduced by controlling the conduction or the disconnection of different groups of switching elements in one switching period. The requirement of high conversion efficiency can be achieved even with small-sized inductors. Therefore, the hybrid power converter can reduce the size of the inductor to achieve miniaturization.

According to the hybrid power converter provided by the invention, in the switched capacitor network, the voltage stress of the switching element is smaller than the input voltage, so that the switching element with low rated voltage is allowed to be adopted. The use of a switching element with a low rated voltage has the advantage of low switching loss and low conduction loss compared to a switching element with a high rated voltage. Therefore, the hybrid power converter can operate at a high switching frequency while improving the conversion efficiency (high efficiency) of the circuit.

According to the hybrid power converter provided by the invention, the inductor and the capacitor are used as energy storage elements together, and the energy density of the capacitor is far higher than that of the inductor. Compared with the traditional power converter only adopting inductance, the hybrid power converter has higher power density (high density). Compared with a traditional power converter only adopting a capacitor, the hybrid converter can realize output voltage regulation capability (regulation), smooth starting of a circuit (smooth starting) and current sharing among multiple circuits (scalability) by utilizing an inductor.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.

Fig. 1a and 1b show a schematic circuit diagram of a switched capacitor network power converter and an operating waveform diagram of a control signal, respectively, according to the prior art.

Fig. 2a and 2b show a schematic circuit diagram of a hybrid power converter according to a first embodiment of the present invention and an operation waveform diagram of a control signal, respectively.

Fig. 3a to 3d are equivalent circuit diagrams of the hybrid power converter according to the first embodiment of the present invention in the first stage, the second stage, the third stage, and the fourth stage, respectively.

Fig. 4a and 4b show a schematic circuit diagram of a hybrid power converter and an operation waveform diagram of a control signal, respectively, according to a second embodiment of the present invention.

Fig. 5a to 5d are equivalent circuit diagrams of a hybrid power converter according to a second embodiment of the present invention in a first stage, a second stage, a third stage, and a fourth stage, respectively.

Fig. 6a and 6b show schematic circuit diagrams of a hybrid power converter according to a third embodiment of the present invention when the number of transistors is even and odd, respectively.

Fig. 6c shows a waveform diagram of the operation of the control signal of the hybrid power converter of fig. 6a and 6 b.

Fig. 7a and 7b show schematic circuit diagrams of a hybrid power converter according to a fourth embodiment of the present invention when the number of transistors is even and odd, respectively.

Fig. 8a and 8b show schematic circuit diagrams of a hybrid power converter according to a fifth embodiment of the present invention when the number of transistors is even and odd, respectively.

Fig. 9a and 9b show schematic circuit diagrams of a hybrid power converter according to a sixth embodiment of the present invention when the number of transistors is even and odd, respectively.

Fig. 10 shows a flowchart of a control method of a hybrid power converter of a seventh embodiment of the present invention.

Detailed Description

The present invention will be described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth. It will be apparent to one skilled in the art that the present invention may be practiced without these specific details. Well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.

Further, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale. Meanwhile, it should be understood that, in the following description, a "circuit" refers to a conductive loop constituted by at least one element or sub-circuit through electrical or electromagnetic connection. When an element or circuit is referred to as being "connected to" another element or element/circuit is referred to as being "connected between" two nodes, it may be directly coupled or connected to the other element or intervening elements may be present, and the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, it is intended that there are no intervening elements present.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, what is meant is "including, but not limited to". In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

The present invention will be described in detail below with reference to the accompanying drawings.

Fig. 2a and 2b show a schematic circuit diagram of a hybrid power converter according to a first embodiment of the present invention and an operation waveform diagram of a control signal, respectively. The power converter 20 receives an input voltage Vi between an input terminal and ground, and provides an output voltage Vo between an output terminal and ground. The power converter 20 includes a first set of switching elements including switching elements Qx and Qy, an inductor Ls, a switched capacitor network including switching elements Q1, Q2, Qa through Qd, and capacitors C1 and C2, and an output capacitor Co.

In the power converter 20, the switching elements Qx and Qy are connected in series between the input terminal of the power converter 20 and the connection node of the switching elements Q1 and Q2 in this order, with the intermediate node of the switching elements Qx and Qy as the first node. A first terminal of the inductor Ls is connected to a first node, a second terminal is connected to the switching element Q1, the switching elements Q1 and Q2 are sequentially connected in series between the second terminal of the inductor Ls and the output terminal of the power converter 20, the switching elements Qa and Qb are sequentially connected in series between the output terminal of the power converter 20 and ground, an intermediate node of the switching elements Qa and Qb is the second node, the switching elements Qd and Qc are sequentially connected in series between the output terminal of the power converter 20 and ground, and an intermediate node of the switching elements Qd and Qc is a third node. The output capacitor Co is connected between the output of the power converter 20 and ground. The capacitor C1 is connected between the second terminal of the inductor Ls and the third node, and the capacitor C2 is connected between the connection node of the switching elements Q1 and Q2 and the second node.

The switching element includes any one selected from a field effect transistor and a bipolar transistor. In this embodiment, the switching element is, for example, an N-type MOSFET, however, the present invention is not limited thereto. The gate of the switching element Qx receives a control signal Gx, the gate of the switching element Qy receives a control signal Gy, the control signals Gx and Gy are periodic signals, the control signals Gx and Gy respectively include an on-time Ton1 and an off-time Toff1 in the respective switching periods, and the control signals Gx and Gy are complementary to each other, i.e., the control signal Gy is inactive when the control signal Gx is active, and vice versa. The gates of the switching elements Q1, Qa, and Qc receive the control signal G1, and the gates of the switching elements Q2, Qb, and Qd receive the control signal G2. The control signals G1 and G2 are periodic signals, the control signals G1 and G2 respectively include an on-time Ton2 and an off-time Toff2 in the respective switching periods, and the control signals G1 and G2 are complementary to each other, i.e., the control signal G2 is inactive when the control signal G1 is active, and vice versa.

For the sake of clarity, the control circuits for generating the control signals G1 and G2, Gx and Gy are not shown in the figure. In the present embodiment, for example, the switching periods of the control signals Gx and Gy are equal to the switching periods of the control signals G1 and G2, except that the duty ratio D1 of the control signal Gx and the duty ratio D2 of the control signal G1 are different, in the present embodiment, the control signal Gx is triggered with a delay of a certain time compared with the control signal G2, of course, the present invention is not limited thereto, and two control signals having the same period T but different duty ratios are used below, each control signal generates a pair of complementary control signals through phase regulation, and the description is only for convenience of describing the operation process of the power converter 20, and the calculation of the proportional relationship between the output voltage Vo and the input voltage Vi should not be taken as a limitation of the present invention.

Specifically, for example, the control circuit generates the control signals G1 and G2, and the control signals Gx and Gy respectively, and the operation timing waveforms of the control signals G1, G2, Gx and Gy are shown in fig. 2 b. The control circuit may adjust the duty cycles D1 and D2 of the control signals Gx and G1, respectively, to change the proportional relationship between the output voltage Vo and the input voltage Vi to achieve the desired output voltage Vo, as described below:

D1＝Ton1/(Ton1+Toff1) (1)

D2＝Ton2/(Ton2+Toff2) (2)

during the operation of the power converter 20, the control signals G1 and G2 in the power converter 20 periodically change, so that the conducting states of the switching elements Q1, Q2, Qa to Qd are correspondingly changed, and similarly, the control signals Gx and Gy are periodically changed, so that the conducting states of the switching elements Qx and Qy are also correspondingly changed, therefore, the connection relationships of the capacitors C1 and C2 are different in different stages of the switching period T, and the charging and discharging states are correspondingly changed.

As shown in fig. 3a, in the first period of the switching period T, i.e., the period from time T1 to T2, the control signals Gx and G2 are active and the control signals Gy and G1 are inactive, the switching elements Qx, Q2, Qb and Qd are turned on, and the switching elements Qy, Q1, Qa and Qc are turned off. The capacitor C1 is connected between the second terminal of the inductor Ls and the output terminal of the power converter 20, and the capacitor C2 is connected between the output terminal of the power converter 20 and ground. The input voltage Vi of the power converter 20 charges the inductor Ls and the capacitor C1, while providing power to the output of the power converter 20. The capacitor C2 discharges to provide power to the output of the power converter 20.

As shown in fig. 3b, in the second period of the switching period T, i.e., the period from time T2 to time T3, the control signals G1 and Gx are active and the control signals G2 and Gy are inactive, the switching elements Qy, Q2, Qb and Qd are turned off, and the switching elements Qa, Qc, Q1 and Qx are turned on. A capacitor C1 is connected between the second terminal of the inductor Ls and ground, and a capacitor C2 is connected between the second terminal of the inductor Ls and the output terminal of the power converter 20. The input voltage Vi charges the inductor Ls and the capacitor C2, and the capacitor C1 charges the capacitor C2 while discharging through the capacitor C2, and provides power to the output of the power converter 20.

As shown in fig. 3c, in the third period of the switching period T, i.e., the period from time T3 to time T4, the control signals G1 and Gy are active and the control signals G2 and Gx are inactive, the switching elements Qx, Q2, Qb and Qd are turned off, and the switching elements Qy, Q1, Qa and Qc are turned on. A capacitor C1 is connected between the second terminal of the inductor Ls and ground, and a capacitor C2 is connected between the second terminal of the inductor Ls and the output terminal of the power converter 20. The input voltage Vi stops charging the inductor Ls, and the inductor Ls keeps constant current; the capacitor C1 charges the capacitor C2 while discharging via the capacitor C2, providing power to the output of the power converter 20.

As shown in fig. 3d, during the fourth period of the switching period T, i.e., the period from T4 to T5, the control signals G2 and Gy are asserted and the control signals G1 and Gx are de-asserted, the switching elements Qx, Q1, Qa and Qc are turned off, and the switching elements Qy, Q2, Qb and Qd are turned on. The capacitor C1 is connected between the second terminal of the inductor Ls and the output terminal of the power converter 20, and the capacitor C2 is connected between the output terminal of the power converter 20 and ground. The input voltage Vi stops charging the inductor Ls, which discharges to charge the capacitor C1, while the capacitor C2 discharges to provide power to the output of the power converter 20.

In the continuous switching period T, according to the charge balance principle of the capacitors in the switched capacitor network, the direct-current voltage Vc1 on the capacitor C1 is equal to 2Vo and the direct-current voltage Vc2 on the capacitor C2 is equal to Vo in a steady state. As shown in fig. 3a, in the first period of the switching period T, i.e. the period from T1 to T2, the voltage at the first terminal of the inductor Ls is equal to Vi and the voltage at the second terminal of the inductor Ls is equal to (Vc1+ Vo is 3 Vo). As shown in fig. 3b, in the second period of the switching cycle T, i.e. the period from time T2 to T3, the voltage at the first terminal of the inductor Ls is equal to Vi and the voltage at the second terminal of the inductor Ls is equal to (Vc1 ═ 2 Vo). As shown in fig. 3c, in the third period of the switching cycle T, i.e. the period from T3 to T4, the voltage across the inductor Ls is equal to 0. As shown in fig. 3d, during the fourth period of the switching period T, i.e. the period from T4 to T5, the voltage at the first terminal of the inductor Ls is equal to Vo and the voltage at the second terminal of the inductor Ls is equal to (Vc1+ Vo is 3 Vo).

According to the volt-second balance principle of the inductance, the following can be known:

(t2-t1)*(Vi-3Vo)+(t3-t2)*(Vi-2Vo)+(t5-t4)*(Vo-3*Vo)＝0(3)

from fig. 2b it can be derived:

(t2-t1)+(t3-t2)＝Ton1 (4)

(t5-t4)+(t4-t3)＝Toff1 (5)

(t2-t1)+(t5-t4)＝Toff2 (6)

(t3-t2)+(t4-t3)＝Ton2 (7)

also in accordance with the foregoing, there can be obtained:

Ton1+Toff1＝Ton2+Toff2＝T (8)

in summary of equations (1) through (8), the process yields: during successive switching cycles, the output voltage Vo of the power converter 20 in steady state is as follows,

Vo＝Vi*D1/{3-D2-[2*(t4-t3)+(t5-t4)/T]} (9)

where Vi denotes an input voltage, D1 denotes a duty ratio of the control signal Gx, D2 denotes a duty ratio of the control signal G1, and T denotes a switching cycle of each control signal.

The power converter according to the first embodiment, operating as a buck converter, provides an output voltage Vo proportional to the input voltage Vi. The number of capacitors in the switched capacitor network is 2 to obtain a predetermined voltage range of 2 or more. Further, within the predetermined voltage range, a desired output voltage is obtained by adjusting the duty ratio D1 of the control signal Gx and the duty ratio D2 of the control signal G1, respectively. Therefore, the power converter can improve the output voltage regulation capability (regulation) of the circuit and obtain the expected conversion ratio.

Fig. 4a and 4b show a schematic circuit diagram of a hybrid power converter and an operation waveform diagram of a control signal, respectively, according to a second embodiment of the present invention. The power converter 30 receives an input voltage Vi between an input terminal and ground, and provides an output voltage Vo between an output terminal and ground. The power converter 30 also includes a first set of switching elements including switching elements Qx and Qy, an inductor Ls, a switched capacitor network including switching elements Q1, Q2, Qa through Qd and capacitors C1 and C2, and an output capacitor Co, the specific circuit connections of which are similar to those described above with respect to the first embodiment of fig. 2 a. Except that switching elements Qx and Qy are in turn connected in series between the input of power converter 30 and the output of power converter 30.

For the sake of clarity, the control circuits for generating the control signals G1 and G2, Gx and Gy are not shown in the figure. In the present embodiment, for example, the switching periods of the control signals Gx and Gy are equal to the switching periods of the control signals G1 and G2, except that the duty ratio D1 of the control signal Gx and the duty ratio D2 of the control signal G1 are different, in the present embodiment, the control signal Gx is triggered with a delay of a certain time compared with the control signal G2, of course, the present invention is not limited thereto, and two control signals having the same period T but different duty ratios are used below, each control signal generates a pair of complementary control signals through phase regulation, and the description is only for convenience of describing the operation process of the power converter 30 and the calculation of the proportional relationship between the output voltage Vo and the input voltage Vi, and should not be taken as a limitation to the present invention.

Specifically, for example, the control circuit generates the control signals G1 and G2, and the control signals Gx and Gy respectively, and the operation timing waveforms of the control signals G1, G2, Gx and Gy are shown in fig. 4 b. The control circuit may adjust the duty cycles D1 and D2 of the control signals Gx and G1, respectively, to change the proportional relationship between the output voltage Vo and the input voltage Vi to achieve the desired output voltage Vo, as described below:

D1＝Ton1/(Ton1+Toff1) (10)

D2＝Ton2/(Ton2+Toff2) (11)

It should be noted that, in the following embodiments, the descriptions about the control signals G1 and G2, and Gx and Gy are the same, and the above-mentioned formulas (4) to (8) can be obtained according to the same operation timing waveforms of the control signals G1, G2, Gx and Gy, and therefore, the description is omitted.

As shown in fig. 5a, in the first period of the switching period T, i.e., the period from time T1 to T2, the control signals Gx and G2 are active and the control signals Gy and G1 are inactive, the switching elements Qx, Q2, Qb and Qd are turned on, and the switching elements Qy, Q1, Qa and Qc are turned off. The capacitor C1 is connected between the second terminal of the inductor Ls and the output terminal of the power converter 30, and the capacitor C2 is connected between the output terminal of the power converter 30 and ground. The input voltage Vi of the power converter 30 charges the inductor Ls and the capacitor C1, while providing power to the output of the power converter 30. Capacitor C2 discharges to provide power to the output of power converter 30.

As shown in fig. 5b, in the second period of the switching period T, i.e., the period from time T2 to time T3, the control signals G1 and Gx are active and the control signals G2 and Gy are inactive, the switching elements Qy, Q2, Qb and Qd are turned off, and the switching elements Qa, Qc, Q1 and Qx are turned on. A capacitor C1 is connected between the second terminal of the inductor Ls and ground, and a capacitor C2 is connected between the second terminal of the inductor Ls and the output of the power converter 30. The input voltage Vi charges the inductor Ls and the capacitor C2, the capacitor C1 charges the capacitor C2 while discharging via the capacitor C2, and provides power to the output of the power converter 30.

As shown in fig. 5c, in the third period of the switching period T, i.e., the period from time T3 to time T4, the control signals G1 and Gy are active and the control signals G2 and Gx are inactive, the switching elements Qx, Q2, Qb and Qd are turned off, and the switching elements Qy, Q1, Qa and Qc are turned on. A capacitor C1 is connected between the second terminal of the inductor Ls and ground, and a capacitor C2 is connected between the second terminal of the inductor Ls and the output of the power converter 30. The input voltage Vi stops charging the inductor Ls, and the inductor Ls discharges to charge the C2; the capacitor C1 charges the capacitor C2 while discharging via the capacitor C2 and provides power to the output of the power converter 30.

As shown in fig. 5d, in the fourth period of the switching period T, i.e., the period from T4 to T5, the control signals G2 and Gy are active and the control signals G1 and Gx are inactive, the switching elements Qx, Q1, Qa and Qc are turned off, and the switching elements Qy, Q2, Qb and Qd are turned on. A capacitor C1 is connected between the second terminal of the inductor Ls and the output of the power converter 30, and a capacitor C2 is connected between the output of the power converter 30 and ground. The input voltage Vi stops charging the inductor Ls, the inductor Ls discharges to charge the capacitor C1 and simultaneously provide power to the output of the power converter 30, and the capacitor C2 discharges also to provide power to the output of the power converter 30.

In the continuous switching period T, according to the charge balance principle of the capacitors in the switched capacitor network, the direct-current voltage Vc1 on the capacitor C1 is equal to 2Vo and the direct-current voltage Vc2 on the capacitor C2 is equal to Vo in a steady state. As shown in fig. 5a, in the first period of the switching period T, i.e. the period from T1 to T2, the voltage at the first terminal of the inductor Ls is equal to Vi and the voltage at the second terminal of the inductor Ls is equal to (Vc1+ Vo is 3 Vo). As shown in fig. 5b, in the second period of the switching cycle T, i.e. the period from time T2 to T3, the voltage at the first terminal of the inductor Ls is equal to Vi and the voltage at the second terminal of the inductor Ls is equal to (Vc1 ═ 2 Vo). As shown in fig. 5c, in the third period of the switching period T, i.e. the period from T3 to T4, the voltage at the first end of the inductor Ls is equal to Vo and the voltage at the second end of the inductor Ls is equal to (Vc2+ Vo is 2 Vo). As shown in fig. 5d, in the fourth period of the switching period T, i.e. the period from T4 to T5, the voltage at the first terminal of the inductor Ls is equal to Vo and the voltage at the second terminal of the inductor Ls is equal to (Vc1+ Vo is 3 Vo).

(t2-t1)*(Vi-3Vo)+(t3-t2)*(Vi-2Vo)+(t4-t3)*(Vo-2Vo)+(t5-t4)*(Vo-3Vo)＝0 (12)

combining the above equations (4) to (8) and equations (10) to (12), the process yields: during successive switching cycles, the output voltage Vo of power converter 30 in steady state is as follows,

Vo＝Vi*D1/(2-D2+D1) (13)，

where Vi denotes an input voltage, D1 denotes a duty ratio of the control signal Gx, and D2 denotes a duty ratio of the control signal G1.

The power converter according to the second embodiment, operating as a buck converter, provides an output voltage Vo proportional to the input voltage Vi. The number of capacitors in the switched capacitor network is 2 to obtain a predetermined voltage range of 0 to 1/2. Further, within the predetermined voltage range, a desired output voltage is obtained by adjusting the duty ratio D1 of the control signal Gx and the duty ratio D2 of the control signal G1, respectively. Therefore, the power converter can improve the output voltage regulation capability (regulation) of the circuit and obtain the expected conversion ratio.

Fig. 6a and 6b show schematic circuit diagrams of a hybrid power converter according to a third embodiment of the present invention when the number of transistors is even and odd, respectively. Fig. 6c shows a waveform diagram of the operation of the control signal of the hybrid power converter of fig. 6a and 6 b. The power converter 40 couples an input voltage Vi between the input and ground, providing an output voltage Vo between the output and ground. The power converter 40 includes a first set of switching elements including switching elements Qx and Qy, an inductor Ls, a switched capacitor network including switching elements Q1, Q2, Q3 through Q (n-1), Qn, and Qa through Qd, capacitors C1, C2, C3 through Cn, and an output capacitor Co.

In the power converter 40, the switching elements Qx and Qy are sequentially connected in series between the input terminal of the power converter 40 and the ground, the intermediate node of the switching elements Qx and Qy serves as a first node, the first terminal of the inductor Ls is connected to the first node, the second terminal is connected to the switching element Q1, the switching elements Q1, Q2, Q3 to Q (n-1), Qn are sequentially connected in series between the second terminal of the inductor Ls and the output terminal of the power converter 40, wherein the switching elements Qa and Qb are sequentially connected in series between the output terminal of the power converter 40 and the ground, the switching elements Qd and Qc are sequentially connected in series between the output terminal of the power converter 40 and the ground, and the output capacitor Co is connected between the output terminal of the power converter 40 and the ground. An intermediate node of the switching elements Qa and Qb is a second node, and an intermediate node of the switching elements Qd and Qc is a third node. A capacitor C1 is connected between the second terminal of the inductor Ls and the third node, a capacitor C2 is connected between the second node and the intermediate node of the switching elements Q1 and Q2, and a capacitor C3 is connected between the third node and the intermediate node of the switching elements Q2 and Q3. When n is an even number, Q1, Q3, and Q (n-1) are respectively odd-numbered switching elements, and Q2 and Qn are respectively even-numbered switching elements. By analogy, the capacitor Cn is connected between the intermediate node of the switching element Q (n-1) and Qn and the second node, as shown in fig. 6 a; when n is an odd number, Q1, Q3, and Qn are odd-numbered switching elements, respectively, and Q2 and Q (n-1) are even-numbered switching elements, respectively. By analogy, a capacitor Cn is connected between the intermediate node of the switching elements Q (n-1) and Qn and the third node, as shown in fig. 6 b.

The switching element includes any one selected from a field effect transistor and a bipolar transistor. In this embodiment, the switching element is, for example, an N-type MOSFET, however, the present invention is not limited thereto. In this embodiment and fig. 6a, the gate of the switching element Qx receives the control signal Gx, the gate of the switching element Qy receives the control signal Gy, the gates of the switching elements Q1, Q3, … …, Q (n-1), Qa, and Qc receive the control signal G1, and the gates of the switching elements Q2, … …, Qn, Qb, and Qd receive the control signal G2. The generation of the control signals Gx and Gy and the control signals G1 and G2 and the relationship therebetween are the same as those described in the above embodiment, and the working waveforms of the control signals are as shown in fig. 6b, which is the same as that described in fig. 4b, and will not be described again.

During the operation of the power converter 40, the control signals G1 and G2 in the power converter 40 periodically change, and the on states of the switching elements Q1, Q2, Q3 to Q (n-1), Qn and Qa to Qd are changed accordingly, and similarly, the control signals Gx and Gy are periodically changed, so that the on states of the switching elements Qx and Qy are changed accordingly, and therefore, the connection relationships of the capacitors C1, C2, C3 to Cn are different in different stages of the switching period T, so that the charging and discharging states are changed accordingly.

Based on the similar principle of the first and second embodiments described above, in successive switching cycles, the output voltage Vo of the power converter 40 in the steady state is as follows,

Vo＝Vi*D1/{N+1-D2-[N*(t4-t3)+(N-1)*(t5-t4)]/T} (14)

where Vi denotes an input voltage, D1 denotes a duty ratio of the control signal Gx, D2 denotes a duty ratio of the control signal G1, N denotes the number of capacitors, N is a natural number equal to or greater than 1, and T denotes a switching period of each control signal.

The power converter according to the third embodiment, operating as a buck converter, provides an output voltage Vo proportional to the input voltage Vi. The number of capacitors in the switched capacitor network is N to obtain a predetermined voltage range of 0 to Vi/N. Further, within the predetermined voltage range, by adjusting the duty ratio D1 of the control signal Gx and the duty ratio D2 of the G1, respectively, a desired output voltage can be obtained. Therefore, the power converter can improve the output voltage regulation capability (regulation) of the circuit and obtain the expected conversion ratio.

Fig. 7a and 7b show schematic circuit diagrams of a hybrid power converter according to a fourth embodiment of the present invention when the number of transistors is even and odd, respectively. Referring to fig. 7a, a power converter 50 taps an input voltage Vi between an input terminal and ground, providing an output voltage Vo between an output terminal and ground. The power converter 50 also includes a first set of switching elements including switching elements Qx and Qy, an inductor Ls, a switched capacitor network including switching elements Q1, Q2, Q3 through Q (n-1), Qn, and Qa through Qd, capacitors C1, C2, C3 through Cn, and an output capacitor Co. The specific circuit connection relationship is similar to that of the third embodiment shown in fig. 6 a. In contrast, in the power converter 50, the switching elements Qx and Qy are connected in series between the input terminal of the power converter 30 and the intermediate nodes of the switching elements Q1 and Q2 in order.

The switching element includes any one selected from a field effect transistor and a bipolar transistor. In this embodiment, the switching element is, for example, an N-type MOSFET, however, the present invention is not limited thereto. In this embodiment and fig. 7a, the gate of the switching element Qx receives the control signal Gx, the gate of the switching element Qy receives the control signal Gy, the gates of the switching elements Q1, Q3, … …, Q (n-1), Qa, and Qc receive the control signal G1, and the gates of the switching elements Q2, … …, Qn, Qb, and Qd receive the control signal G2. The generation of the control signals Gx and Gy and the control signals G1 and G2 and the relationship therebetween are the same as those described in the above embodiment, and the working waveforms of the control signals are the same as those described in the above fig. 4b and fig. 6b, which are not repeated herein.

During the operation of the power converter 50, the control signals G1 and G2 in the power converter 50 periodically change, and the on states of the switching elements Q1, Q2, Q3 to Q (n-1), Qn and Qa to Qd are changed accordingly, and similarly, the control signals Gx and Gy are periodically changed, so that the on states of the switching elements Qx and Qy are changed accordingly, and therefore, the connection relationships of the capacitors C1, C2, C3 to Cn are different in different stages of the switching period T, so that the charging and discharging states are changed accordingly.

Based on the similar principle of the first to third embodiments, the relationship between the output voltage Vo and the input voltage Vi of the power converter 50 in the steady state in consecutive switching cycles is the same as the above equation (14), wherein the reference relationship of each parameter is the same as that in the third embodiment.

It should be noted that fig. 7a only shows the connection relationship of the capacitors when N is even, it can be understood that the connection relationship of the capacitors when N is odd, as shown in fig. 7b, can be compared with the connection relationship of the circuits in the third embodiment shown in fig. 6a and 6b, and details are not repeated herein.

The power converter according to the fourth embodiment, operating as a buck converter, provides an output voltage Vo proportional to the input voltage Vi. The number of capacitors in the switched capacitor network is N to obtain a predetermined voltage range of 0 to Vi/N. Further, within the predetermined voltage range, by adjusting the duty ratio D1 of the control signal Gx and the duty ratio D2 of the G1, respectively, a desired output voltage can be obtained. Therefore, the power converter can improve the output voltage regulation capability (regulation) of the circuit and obtain the expected conversion ratio.

Fig. 8a and 8b show schematic circuit diagrams of a hybrid power converter according to a fourth embodiment of the present invention when the number of transistors is even and odd, respectively. Referring to fig. 8a, the power converter 60 taps an input voltage Vi between an input terminal and ground, providing an output voltage Vo between an output terminal and ground. The power converter 60 also includes a first set of switching elements including switching elements Qx and Qy, an inductor Ls, a switched capacitor network including switching elements Q1, Q2, Q3 through Q (n-1), Qn, and Qa through Qd, capacitors C1, C2, C3 through Cn, and an output capacitor Co. The specific circuit connection relationship is similar to that of the third embodiment shown in fig. 6 a. In contrast, in the power converter 60, the switching elements Qx and Qy are sequentially connected in series between the input terminal of the power converter 60 and the output terminal of the power converter 60.

The switching element is also any one selected from a field effect transistor and a bipolar transistor. In this embodiment, the switching element is, for example, an N-type MOSFET, however, the present invention is not limited thereto. In this embodiment and fig. 8a, the gate of the switching element Qx receives the control signal Gx, the gate of the switching element Qy receives the control signal Gy, the gates of the switching elements Q1, Q3, … …, Q (n-1), Qa, and Qc receive the control signal G1, and the gates of the switching elements Q2, … …, Qn, Qb, and Qd receive the control signal G2. The generation of the control signals Gx and Gy and the control signals G1 and G2 and the relationship therebetween are the same as those described in the above embodiment, and the working waveforms of the control signals are the same as those described in the above fig. 4b and fig. 6b, which are not repeated herein.

During the operation of the power converter 60, the control signals G1 and G2 in the power converter 60 periodically change, and the on states of the switching elements Q1, Q2, Q3 to Q (n-1), Qn and Qa to Qd are changed accordingly, and similarly, the control signals Gx and Gy are periodically changed, so that the on states of the switching elements Qx and Qy are changed accordingly, and therefore, the connection relationships of the capacitors C1, C2, C3 to Cn are different in different stages of the switching period T, so that the charging and discharging states are changed accordingly.

Based on the similar principle of the third and fourth embodiments, the relationship between the output voltage Vo and the input voltage Vi of the power converter 60 in the steady state in consecutive switching cycles is the same as the above equation (14), wherein the reference relationship of each parameter is the same as that in the third embodiment.

It should be noted that fig. 8a only shows the connection relationship of the capacitors when N is even, it can be understood that the connection relationship of the capacitors when N is odd, as shown in fig. 8b, can be compared with the connection relationship of the circuits in the third embodiment shown in fig. 6a and 6b, and details are not repeated herein.

The power converter according to the fifth embodiment, operating as a buck converter, provides an output voltage Vo proportional to the input voltage Vi. The number of capacitors in the switched capacitor network is N to obtain a predetermined voltage range of 0 to Vi/N. Further, within the predetermined voltage range, by adjusting the duty ratio D1 of the control signal Gx and the duty ratio D2 of the G1, respectively, a desired output voltage can be obtained. Therefore, the power converter can improve the output voltage regulation capability (regulation) of the circuit and obtain the expected conversion ratio.

In a further embodiment of the present invention, the input terminal and the output terminal in the above embodiments can be exchanged, that is, the input voltage Vi connected between the input terminal of the power converter and the ground is exchanged with the output capacitor Co connected between the output terminal of the power converter and the ground, so that the hybrid power converter originally operating as a buck converter operates as a boost converter, which can provide the output voltage Vo proportional to the input voltage Vi, as shown in fig. 9a and 9b with reference to the fifth embodiment.

According to the power converter of the sixth embodiment, the power converter 70 also includes a first set of switching elements including switching elements Qx and Qy, an inductor Ls, a switched capacitor network including switching elements Q1, Q2, Q3 to Q (n-1), Qn, and Qa to Qd, and capacitors C1, C2, C3 to Cn, and an output capacitor Co. The specific circuit connection relationship is similar to that in the fourth embodiment shown in fig. 8. In contrast, in the power converter 70, an input voltage Vi is connected between the second terminal of the power converter 70 and ground, and an output voltage Vo is provided between the first terminal of the power converter 70 and ground.

The switching element is also any one selected from a field effect transistor and a bipolar transistor. In this embodiment, the switching element is, for example, an N-type MOSFET, however, the present invention is not limited thereto. In this embodiment and fig. 9a, the gate of the switching element Qx receives the control signal Gx, the gate of the switching element Qy receives the control signal Gy, the gates of the switching elements Q1, Q3, … …, Q (n-1), Qa, and Qc receive the control signal G1, and the gates of the switching elements Q2, … …, Qn, Qb, and Qd receive the control signal G2. The generation of the control signals Gx and Gy and the control signals G1 and G2 and the relationship therebetween are the same as those described in the above embodiment, and the working waveforms of the control signals are the same as those described in the above fig. 4b and fig. 6b, which are not repeated herein.

During the operation of the power converter 70, the control signals G1 and G2 in the power converter 70 periodically change, and the on states of the switching elements Q1, Q2, Q3 to Q (n-1), Qn and Qa to Qd are changed accordingly, and similarly, the control signals Gx and Gy are periodically changed, so that the on states of the switching elements Qx and Qy are changed accordingly, and therefore, the connection relationships of the capacitors C1, C2, C3 to Cn are different in different stages of the switching period T, and the charging and discharging states are changed accordingly.

During the operation of the power converter 70, the control signals G1 and G2 in the power converter 70 periodically change, and the on states of the switching elements Q1, Q2, Q3 to Q (n-1), Qn, and Qa to Qd correspondingly change, so that the connection relationships of the capacitors C1 to C3 are different at different stages of the switching period T, and the charging and discharging states correspondingly change.

Based on a similar principle of the sixth embodiment, in successive switching cycles, the output voltage Vo of the boost type power converter in the steady state is as follows,

Vo＝Vi*(N-D2+D1)/D1 (15)

where Vi denotes an input voltage, D1 denotes a duty ratio of the control signal Gx, D2 denotes a duty ratio of the control signal G1, N denotes the number of capacitors, and N is a natural number equal to or greater than 2. The number of capacitors in the switched capacitor network is N to obtain a predetermined voltage range greater than or equal to Vi (N + 1). Further, within the predetermined voltage range, by adjusting the duty ratio D1 of the control signal Gx and the duty ratio D2 of the control signal G1, respectively, a desired input voltage can be obtained. Therefore, the power converter can improve the output voltage regulation capability (regulation) of the circuit and obtain the expected conversion ratio.

Fig. 10 shows a flowchart of a control method of a hybrid power converter of a seventh embodiment of the present invention. This control method is applied to the hybrid power converter according to any one of the first to sixth embodiments described above.

The power converter comprises a first group of switching elements, an inductor and a switched capacitor network which are sequentially connected between a first end and a second end, wherein the switched capacitor network comprises a plurality of switching elements and a plurality of capacitors. Referring to fig. 9a and 9b, capacitors C1, C2, C3 to Cn are connected in series to nodes of adjacent ones of a plurality of switching elements Q1, Q2, Q3 to Q (n-1), Qn, which when n is an even number, include a first group of odd numbered capacitors C1, C3 and a second group of even numbered capacitors C2, Cn. When n is an odd number, the plurality of capacitors includes a first group of capacitors C1, C3, and Cn numbered odd, and a second group of capacitors C2, C (n-1) numbered even.

In step S110, the number of the aforementioned plurality of capacitors is selected in the switched capacitor network to obtain a predetermined voltage range.

In step S120, a first set of control signals is used to control the first set of switching elements to turn on and off to change the connection state of the first terminal of the power converter.

In step S130, a second set of control signals is used to control the on and off of the plurality of switching elements in the switched capacitor network to change the connection paths of the plurality of capacitors, so that the inductor and the plurality of capacitors are charged and discharged.

In step S140, the duty ratios of the first and second sets of control signals are adjusted to obtain the desired output voltages within the predetermined voltage range, respectively.

Further, in the step S120, the first terminal of the power converter and the inductor are controlled to be in a conducting state in the first time period and the second time period of each switching cycle; and controlling the first end of the power converter and the inductor to be in a cut-off state in a third time period and a fourth time period of each switching cycle.

In the step S130, in the first period and the fourth period of each switching cycle, the first end of the first capacitor of the first group of capacitors is connected to the second end of the inductor, the first ends of the rest capacitors of the first group of capacitors are connected to ground, the second ends of the first group of capacitors are connected to the second end of the power converter, and the first ends of the second group of capacitors are connected to the second end of the power converter, and the second ends of the second group of capacitors are connected to ground; and

For example, with continued reference to fig. 9a and 9b, the first end of the capacitor C3 of the aforementioned first set of capacitors is connected to the second end of the power converter via a respective one of the capacitors C2 of the second set of capacitors or to ground via a respective one of the capacitors C4 of the second set of capacitors, and the first end of the second set of capacitors C2 is connected to the second end of the power converter via a respective one of the capacitors C3 of the first set of capacitors or to ground via a respective one of the capacitors C1 of the first set of capacitors.

It should be noted that in the description of the present invention, it is to be understood that the terms "upper", "lower", "inner", and the like, indicate orientation or positional relationship, are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referenced components or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.

Further, in this document, the contained terms "include", "contain" or any other variation thereof are intended to cover a non-exclusive inclusion, so that a process, a method, an article or an apparatus including a series of elements includes not only those elements but also other elements not explicitly listed or inherent to such process, method, article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.

Claims

1. A hybrid power converter, comprising:

an inductor connected to a connection node between the first group of switching elements;

a switched capacitor network connected between the inductor and the second terminal of the hybrid power converter, including a second set of switching elements and a plurality of capacitors, and controlling the second set of switching elements to be turned on and off according to a second set of control signals, thereby periodically changing a connection path of the plurality of capacitors such that the inductor and the plurality of capacitors are charged and discharged,

wherein the first set of control signals includes a first control signal and a second control signal, the first control signal and the second control signal are periodic and complementary signals to each other, the second set of control signals includes a third control signal and a fourth control signal, the third control signal and the fourth control signal are periodic and complementary signals to each other, the second control signal and the third control signal have the same period, and the second control signal is triggered by delaying for a period of time compared to the third control signal,

the second set of switching elements comprises:

a first type of switching element comprising a first switching element and a second switching element connected in series between a second terminal of the power converter and ground, the first and second switching elements forming a second node;

a third type of switching element connected in series between the inductor and a second terminal of the power converter, the third type of switching element forming a fourth set of nodes with the inductor and with each other,

wherein the plurality of capacitors have first terminals sequentially connected to respective nodes in the fourth set of nodes and second terminals alternately connected to one of the second and third nodes, and the hybrid power converter adjusts duty cycles of the first and second sets of control signals, respectively, to convert an input voltage to a desired output voltage.

2. The hybrid power converter of claim 1, wherein the first set of switching elements includes fifth and sixth switching elements connected in series between the first terminal of the power converter and one of the connection nodes formed between the switching elements of the third type.

3. The hybrid power converter of claim 1, the number of switching elements of the third type being the same as the number of capacitors.

4. The hybrid power converter of claim 2, wherein the control terminal of the fifth switching element receives the first control signal and the control terminal of the sixth switching element receives the second control signal;

the control terminals of the odd-numbered ones of the first, third, and third classes of switching elements receive the third control signal, and the control terminals of the even-numbered ones of the second, fourth, and third classes of switching elements receive the fourth control signal.

5. The hybrid power converter of claim 4, wherein a number of the plurality of capacitors is selected in the switched capacitor network to achieve a predetermined voltage range by adjusting duty cycles of the first and second control signals to achieve a desired output voltage within the predetermined voltage range.

6. The hybrid power converter of claim 4, wherein a first terminal of the hybrid power converter is an input terminal to receive the input voltage, a second terminal of the power converter is an output terminal to provide the output voltage, and the hybrid power converter operates as a buck converter.

7. The hybrid power converter of claim 6, wherein the output voltage at steady state during successive switching cycles of the hybrid power converter is as follows,

Vo＝Vi*D1/{N+1-D2-[N*(t4-t3)+(N-1)*(t5-t4)]/T} (14)

8. The hybrid power converter of claim 6, further comprising: an output capacitance connected between the second terminal of the power converter and ground.

9. The hybrid power converter of claim 4, wherein the second terminal of the hybrid power converter serves as an input terminal to receive the input voltage, the first terminal of the power converter serves as an output terminal to provide the output voltage, and the hybrid power converter operates as a boost converter.

10. The hybrid power converter of claim 9, wherein the output voltage at steady state during successive switching cycles of the hybrid power converter is as follows,

Vo＝Vi*(N-D2+D1)/D1 (15)

11. The hybrid power converter of claim 9, further comprising: an output capacitance connected between the first terminal of the power converter and ground.

12. A method of controlling a hybrid power converter comprising a first set of switching elements connected between a first terminal and a second terminal, an inductor and a switched capacitor network according to any of claims 1 to 11, the switched capacitor network comprising a second set of switching elements and a plurality of capacitors, the method comprising:

selecting a number of the plurality of capacitors in the switched capacitor network to obtain a predetermined voltage range;

controlling the first group of switching elements to be switched on and off by using a periodic first group of control signals so as to change the connection state of the first end of the power converter;

controlling the second group of switch elements in the switched capacitor network to be switched on and off by using a periodic second group of control signals to change the connection paths of the plurality of capacitors, so that the inductor and the plurality of capacitors are charged and discharged; and

adjusting duty cycles of the first and second sets of control signals, respectively, to obtain a desired output voltage within the predetermined voltage range,

the first group of control signals comprises a first control signal and a second control signal, the first control signal and the second control signal are periodic and complementary signals, the second group of control signals comprises a third control signal and a fourth control signal, the third control signal and the fourth control signal are periodic and complementary signals, the second control signal and the third control signal have the same period, and the second control signal is triggered by delaying for a period of time compared with the third control signal.

13. The control method of claim 12, wherein the plurality of capacitors are sequentially connected to nodes of adjacent ones of the second set of switching elements and comprise an odd numbered first set of capacitors and an even numbered second set of capacitors.

14. The control method of claim 13, wherein the step of controlling the turning on and off of the first set of switching elements with a periodic first set of control signals comprises:

15. The control method of claim 13, wherein controlling the second set of switching elements in the switched-capacitor network to turn on and off with a periodic second set of control signals comprises:

connecting a first terminal of a first capacitor of the first set of capacitors to a second terminal of the inductor, a first terminal of the remaining capacitors of the first set of capacitors each being connected to ground, a second terminal of the first set of capacitors each being connected to a second terminal of the power converter, and a first terminal of a second set of capacitors each being connected to a second terminal of the power converter, a second terminal of the second set of capacitors each being connected to ground during a first time period and a fourth time period of each switching cycle;

in the second time period and the third time period of each switching cycle, connecting the first end of the first capacitor of the first group of capacitors to the second end of the inductor, connecting the first ends of the rest capacitors of the first group of capacitors to the second end of the power converter, connecting the second ends of the first group of capacitors to ground, and connecting the first ends of the second group of capacitors to ground, connecting the second ends of the second group of capacitors to the second end of the power converter.

16. The control method of claim 15, wherein first ends of remaining capacitors of the first set of capacitors are connected to a second end of the power converter or ground via a respective one of the second set of capacitors, the first ends of the second set of capacitors being connected to the second end of the power converter or ground via a respective one of the first set of capacitors.