Switched-capacitor voltage conversion circuit and switched-capacitor voltage conversion method

Abstract

A switched-capacitor voltage conversion circuit and a switched-capacitor voltage conversion method. The switched-capacitor voltage conversion circuit includes a switched-capacitor converter and a control circuit. In a charging procedure of a resonance mode, switching of a plurality of switches is controlled by a charging operation signal to form a charging path by connecting at least one capacitor and a corresponding inductor in series between a first voltage and a second voltage. In a discharging procedure of the resonance mode, switching of the plurality of switches is controlled by a discharging operation signal to form a plurality of discharging paths by connecting the capacitor and the corresponding inductor in series between the second voltage and a direct current potential at the same time or alternately. In an inductor switching mode, switching of the plurality of switches is controlled by an inductor operation signal to alternately connect one end of the inductor to the first voltage and the direct current potential. The control circuit selects the resonance mode or the inductor switching mode according to the first voltage to maintain the second voltage within a predetermined range.

Description

TECHNICAL FIELD

[0001] The present application relates to a switched-capacitor voltage conversion circuit, and in particular to a switched-capacitor voltage conversion circuit and method capable of automatically switching between multiple operation modes. BACKGROUND

[0002] Figure 1 A known resonant switched-capacitor voltage converter 10 is shown. The known resonant switched-capacitor voltage converter 10 has a voltage conversion ratio of 2: 1 from an input voltage Vin to an output voltage Vout, and is capable of providing high efficiency operation when its switching operation is at a resonant frequency and switching between flexible switching states with zero-current switching / zero-voltage switching. However, due to its fixed 2: 1 conversion ratio, its output voltage Vout has a wide range, thus limiting its applications to applications with wide input voltage conditions. SUMMARY

[0003] In one aspect, the present application provides a switched-capacitor voltage conversion circuit for converting a first voltage to a second voltage or converting the second voltage to the first voltage, the switched-capacitor voltage conversion circuit comprising: a switched-capacitor converter coupled between the first voltage and the second voltage; and a control circuit for generating a control signal to control the switched-capacitor converter to convert the first voltage to the second voltage or convert the second voltage to the first voltage; wherein the switched-capacitor converter comprises: at least one capacitor; a plurality of switches coupled with the at least one capacitor; and at least one inductor; wherein the control circuit is configured to select a ratio between the first voltage and the second voltage according to a level of the first voltage and with an objective of maintaining the second voltage within a first predetermined range, and to generate the control signal to convert the first voltage to the second voltage, or the control circuit is configured to select a ratio between the first voltage and the second voltage according to a level of the second voltage and with an objective of maintaining the first voltage within a second predetermined range, and to generate the control signal to convert the second voltage to the first voltage; wherein the control signal comprises a charging operation signal and at least one discharging operation signal; wherein in a charging procedure of a resonant operation mode, the plurality of switches are controlled by the charging operation signal to switch such that the at least one capacitor and a corresponding inductor are coupled in series between the first voltage and the second voltage to form a charging path and to operate in resonance; wherein in at least one discharging procedure of the resonant operation mode, the plurality of switches are controlled by the at least one discharging operation signal to switch such that the at least one capacitor and a corresponding inductor are coupled in series between the second voltage and a DC potential to form or alternately form a plurality of discharging paths and to operate in resonance; wherein in the resonant operation mode, the charging operation signal and the at least one discharging operation signal are each switched to an on level for a plurality of on periods, and the plurality of on periods do not overlap with each other, such that the charging procedure and the at least one discharging procedure do not overlap with each other; wherein in the resonant operation mode, the charging procedure and the at least one discharging procedure are repeatedly interleaved to convert the first voltage to the second voltage or convert the second voltage to the first voltage.

[0004] In one embodiment, the control signal further comprises an inductor operation signal to control the plurality of switches to switch such that the switched-capacitor converter operates in an inductor switching mode, and such that one end of the at least one inductor is alternately coupled to the first voltage or the DC potential to convert the first voltage to the second voltage and maintain the second voltage within the first predetermined range, or to convert the second voltage to the first voltage and maintain the first voltage within the second predetermined range.

[0005] In one embodiment, in the resonant operation mode and / or the inductive switching mode, the control circuit adjusts a duty cycle of the charging operation signal and / or the discharging operation signal and / or the inductive operation signal to cause an inductive current flowing toward the second voltage to be in a first state when some of the switches are turned on, and to cause the inductive current flowing through the corresponding inductor to freewheel through at least one current freewheeling path when none of the switches are turned on, thereby causing the inductive current flowing toward the second voltage to be in a second state, so that the corresponding inductor performs inductive power conversion switching between the first state and the second state.

[0006] In one embodiment, in the resonant operation mode, the first state is that the inductive current flowing toward the second voltage is a resonant current.

[0007] In one embodiment, in the inductive switching mode, the first state is that the inductive current flowing toward the second voltage is a non-resonant current.

[0008] In one embodiment, in the inductive switching mode, the first state is that the inductive current flowing toward the second voltage is a triangular wave current.

[0009] In one embodiment, the second state is that the inductive current flowing toward the second voltage is a non-resonant current.

[0010] In one embodiment, the second state is that the inductive current flowing toward the second voltage is a linear ramp current.

[0011] In one embodiment, in the resonant operation mode and / or the inductive switching mode, the control circuit adjusts the duty cycle of the charging operation signal and / or the discharging operation signal and / or the inductive operation signal to cause the terminal of the corresponding inductor to be turned on to the DC potential through at least one body diode in the switch when none of the switches are turned on, thereby causing the inductive current flowing toward the second voltage to be the linear ramp current.

[0012] In one embodiment, the at least one capacitor includes two capacitors, wherein the resonant operation mode includes a two-to-one mode and / or a three-to-one mode; wherein the control circuit selects the switching capacitor converter to operate in the two-to-one mode or the three-to-one mode according to the first voltage; wherein, in the two-to-one mode, the control circuit controls the switches to cause a single capacitor and a single corresponding inductor to form the charging path and the discharging path respectively and operate in resonance in the charging program and the discharging program; wherein, in the three-to-one mode, the control circuit controls the switches to cause two capacitors and a single corresponding inductor to form the charging path and the discharging path respectively and operate in resonance in the charging program and the discharging program.

[0013] In one embodiment, the control circuit selects one of the two-to-one mode, the three-to-one mode, and the inductive switching mode for the switched capacitor converter to operate in, according to the first voltage, to maintain the second voltage within the first predetermined range.

[0014] In one embodiment, the inductive switching mode includes a second-order inductive switching mode and / or a third-order inductive switching mode, and the inductive operation signal includes a second-order inductive operation signal and / or a third-order inductive operation signal; in the second-order inductive switching mode, the switching of the plurality of switches is controlled by the second-order inductive operation signal to periodically switch the voltage at the terminal of the at least one inductor between the first voltage and the DC potential to convert the first voltage to the second voltage or convert the second voltage to the first voltage; in the third-order inductive switching mode, the switching of the plurality of switches is controlled by the third-order inductive operation signal to periodically switch the voltage at the terminal of the at least one inductor between the first voltage, one-half of the first voltage, and the DC potential to convert the first voltage to the second voltage or convert the second voltage to the first voltage.

[0015] In one embodiment, the control circuit selects one of the two-to-one mode, the three-to-one mode, the second-order inductive switching mode, and the third-order inductive switching mode for the switched capacitor converter to operate in, according to the first voltage, to maintain the second voltage within the first predetermined range.

[0016] In one embodiment, in the two-to-one mode, the first voltage is twice the second voltage; in the three-to-one mode, the first voltage is three times the second voltage.

[0017] In one embodiment, the switched capacitor converter includes a series-parallel switched capacitor converter.

[0018] In one embodiment, the series-parallel switched capacitor converter includes a 2-to-1 series-parallel switched capacitor converter, a 3-to-1 series-parallel switched capacitor converter, a 4-to-1 series-parallel switched capacitor converter, or a 5-to-1 series-parallel switched capacitor converter.

[0019] In one embodiment, the DC potential is a ground potential.

[0020] In one embodiment, the control circuit includes a current sensing circuit for sensing a current flowing through the at least one inductor to generate at least one current sensing signal, and a control signal generating circuit coupled to the current sensing circuit for generating the control signal according to the current sensing signal.

[0021] In one embodiment, the control circuit further includes a voltage sensing circuit for sensing the second voltage or the first voltage to generate a voltage sensing signal, wherein the control signal generating circuit, in the inductor switching mode, further generates the inductor operation signal according to the voltage sensing signal.

[0022] In one embodiment, the at least one capacitor includes N capacitors, wherein the resonance operation mode includes an M-to-1 mode, wherein N is a natural number greater than or equal to 3, and M is a natural number greater than or equal to 2 and less than or equal to N+1; wherein the control circuit determines the value of M according to the first voltage, and selects to operate the switched capacitor converter in the M-to-1 mode; wherein, in the M-to-1 mode, the control circuit controls the plurality of switches, in the charging procedure and the discharging procedure, such that M-1 capacitors and corresponding single inductors respectively correspond to form the charging path and the discharging path and operate in resonance.

[0023] In another aspect, the present application provides a switched-capacitor voltage conversion method for converting a first voltage to a second voltage or vice versa in a switched-capacitor voltage converter, which includes at least one capacitor, a plurality of switches, and at least one inductor. The switched-capacitor voltage conversion method includes: selecting a ratio between the first voltage and the second voltage according to a level of the first voltage, and aiming to maintain the second voltage within a first predetermined range, to generate a control signal for converting the first voltage to the second voltage, or selecting the ratio between the first voltage and the second voltage according to a level of the second voltage, and aiming to maintain the first voltage within a second predetermined range, to generate the control signal for converting the second voltage to the first voltage; in a charging procedure of a resonant operation mode, controlling switching of the plurality of switches by a charging operation signal to make the at least one capacitor and a corresponding inductor be in series between the first voltage and the second voltage to form a charging path and operate in resonance; in at least one discharging procedure of the resonant operation mode, controlling switching of the plurality of switches by at least one discharging operation signal to make the at least one capacitor and a corresponding inductor be in series between the second voltage and a direct-current potential to form or alternately form a plurality of discharging paths and operate in resonance; wherein in the resonant operation mode, the charging operation signal and the at least one discharging operation signal are switched to an on level for a plurality of on periods, respectively, and the plurality of on periods do not overlap with each other, so that the charging procedure and the at least one discharging procedure do not overlap with each other; wherein in the resonant operation mode, the charging procedure and the at least one discharging procedure are repeatedly interleaved to convert the first voltage to the second voltage or vice versa.

[0024] In an embodiment, the switched-capacitor voltage conversion method further includes: in an inductor switching mode, controlling switching of the plurality of switches by an inductor operation signal to make one end of the at least one inductor alternately couple to the first voltage or the direct-current potential to convert the first voltage to the second voltage and maintain the second voltage within the first predetermined range, or convert the second voltage to the first voltage and maintain the first voltage within the second predetermined range.

[0025] In one embodiment, the switched-capacitor voltage conversion method further comprises: in the resonant operation mode and / or the inductive switching mode, reducing a duty cycle of the charging operation signal and / or the discharging operation signal and / or the inductive operation signal, so that an inductive current flowing towards the second voltage is in a first state when some of the plurality of switches are turned on, and the inductive current flowing through the corresponding inductor is freewheeled through at least one freewheeling path when none of the plurality of switches are turned on, so that the inductive current flowing towards the second voltage is in a second state, so that the corresponding inductor performs inductive power conversion switching between the first state and the second state.

[0026] In one embodiment, in the resonant operation mode and / or the inductive switching mode, when the duty cycle of the charging operation signal and / or the discharging operation signal and / or the inductive operation signal is reduced, and none of the plurality of switches are turned on, the terminal of the corresponding inductor is turned on to the DC potential through the body diode in at least one of the switches, so that the inductive current flowing towards the second voltage is the linear ramp current.

[0027] In one embodiment, the at least one capacitor comprises two capacitors, wherein the resonant operation mode comprises a two-to-one mode and / or a three-to-one mode; wherein the switched-capacitor converter is selected to operate in the two-to-one mode or the three-to-one mode according to the first voltage; wherein in the two-to-one mode, the charging operation signal and the discharging operation signal control the plurality of switches, so that in the charging program and the discharging program, a single capacitor and a single corresponding inductor form the charging path and the discharging path respectively and operate in resonance; wherein in the three-to-one mode, the charging operation signal and the discharging operation signal control the plurality of switches, so that in the charging program and the discharging program, two capacitors and a single corresponding inductor form the charging path and the discharging path respectively and operate in resonance.

[0028] In one embodiment, the step of selecting the switched-capacitor converter to operate in the resonant operation mode or the inductive switching mode according to the first voltage comprises selecting the switched-capacitor converter to operate in one of the two-to-one mode, the three-to-one mode and the inductive switching mode according to the first voltage, so as to maintain the second voltage within the first predetermined range.

[0029] In one embodiment, the inductive switching mode includes a second-order inductive switching mode and / or a third-order inductive switching mode, and the inductive operation signal includes a second-order inductive operation signal and / or a third-order inductive operation signal; in the second-order inductive switching mode, the switching of the plurality of switches is controlled by the second-order inductive operation signal to periodically switch the voltage at the end of the at least one inductor between the first voltage and the DC potential to convert the first voltage to the second voltage or convert the second voltage to the first voltage; in the third-order inductive switching mode, the switching of the plurality of switches is controlled by the third-order inductive operation signal to periodically switch the voltage at the end of the at least one inductor between the first voltage, one-half of the first voltage, and the DC potential to convert the first voltage to the second voltage or convert the second voltage to the first voltage.

[0030] In one embodiment, the step of selecting the resonant operation mode or the inductive switching mode for the switched-capacitor voltage converter according to the first voltage includes selecting one of the 2-to-1 mode, the 3-to-1 mode, the second-order inductive switching mode, and the third-order inductive switching mode for the switched-capacitor voltage converter according to the first voltage to maintain the second voltage within the first predetermined range.

[0031] In one embodiment, the switched-capacitor voltage conversion method further includes sensing a current flowing through the at least one inductor to generate at least one current sensing signal, and generating the charging operation signal, the at least one discharging operation signal, and the inductive operation signal according to the current sensing signal.

[0032] In one embodiment, the switched-capacitor voltage conversion method further includes sensing the second voltage or the first voltage to generate a voltage sensing signal, and generating the inductive operation signal according to the voltage sensing signal in the inductive switching mode.

[0033] In one embodiment, the at least one capacitor includes N capacitors, the resonant operation mode includes an M-to-1 mode, where N is a natural number greater than or equal to 3, and M is a natural number greater than or equal to 2 and less than or equal to N+1; the value of M is determined according to the first voltage, and the switched-capacitor voltage converter is selected to operate in the M-to-1 mode; in the M-to-1 mode, the plurality of switches are controlled to form the charging path and the discharging path with M-1 capacitors and a corresponding single inductor, respectively, and operate in resonance.

[0034] The present disclosure provides an innovative switched-capacitor voltage conversion circuit.

[0035] The present application has the advantages that the present application can make the output voltage have a smaller variation range, can provide more operation modes with different voltage conversion ratios, and can achieve automatic mode conversion control among multiple operation modes of the resonant switching capacitor voltage converter by combining the N conversion 1 mode and the second or third order inductive switching mode.

[0036] The purposes, technical contents, features and effects of the present application will be further illustrated in detail by specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 A schematic diagram of a known resonant switching capacitor voltage converter.

[0038] Figure 2A A circuit schematic diagram of a switching capacitor voltage conversion circuit according to an embodiment of the present application.

[0039] Figure 2B A signal waveform schematic diagram of related signals of a switching capacitor voltage conversion circuit according to an embodiment of the present application.

[0040] Figure 2C A block schematic diagram of a control circuit of a switching capacitor voltage conversion circuit according to an embodiment of the present application.

[0041] Figure 3A A circuit schematic diagram of a switching capacitor voltage conversion circuit according to another embodiment of the present application.

[0042] Figure 3B A signal waveform schematic diagram of related signals of a switching capacitor voltage conversion circuit according to an embodiment of the present application.

[0043] Figure 3C A circuit schematic diagram of a switching capacitor voltage conversion circuit according to still another embodiment of the present application.

[0044] Figure 3D A circuit schematic diagram of a switching capacitor voltage conversion circuit according to yet another embodiment of the present application.

[0045] Figure 4 A circuit schematic diagram of a switching capacitor voltage conversion circuit according to still another embodiment of the present application.

[0046] Figure 5 A circuit schematic diagram of a switching capacitor voltage conversion circuit according to yet another embodiment of the present application.

[0047] Figure 6 An operation mode characteristic diagram of a switching capacitor voltage conversion circuit according to an embodiment of the present application.

[0048] Figure 7 is a characteristic diagram showing operation modes of a switched-capacitor voltage conversion circuit according to another embodiment of the present application.

[0049] Figure 8 is a circuit schematic diagram showing a switched-capacitor voltage conversion circuit according to still another embodiment of the present application.

[0050] Figure 9 is a circuit schematic diagram showing a switched-capacitor voltage conversion circuit according to yet another embodiment of the present application.

[0051] Explanation of symbols in the drawings

[0052] 10: resonant switched-capacitor voltage converter

[0053] 20, 30, 30', 40, 50, 60, 70: switched-capacitor voltage conversion circuit

[0054] 201, 601, 701: control circuit

[0055] 202, 602, 702: switched-capacitor converter

[0056] 2011: current sensing circuit

[0057] 2012: control signal generating circuit

[0058] 2013: voltage sensing circuit

[0059] C1 to C4, CV2: capacitor

[0060] Cd: current sensing signal

[0061] GA: charging operation signal

[0062] GB: discharging operation signal

[0063] Gb21, Gb22: second-order inductor operation signal

[0064] Gb31, Gb31: third-order inductor operation signal

[0065] I1: first current

[0066] I2: second current

[0067] IC1: capacitor current

[0068] IL: inductor current

[0069] L: inductor

[0070] Q1 to Q13: switch

[0071] V1: first voltage

[0072] V11, V12, V13, V21, V22: voltage

[0073] V2: second voltage

[0074] Vd: voltage sensing signal

[0075] Vds1, Vds6: drain-source voltage

[0076] Vin: input voltage

[0077] Vout: output voltage

[0078] Vth1: first threshold value

[0079] Vth2: second threshold value

[0080] Vth3: third threshold value

[0081] Vth4: fourth threshold value

[0082] Vth5: fifth threshold value

[0083] Vth6: sixth threshold value DETAILED DESCRIPTION

[0084] The drawings in the present disclosure are schematic and mainly intended to represent the coupling relationship between circuits and the relationship between signal waveforms. The circuits, signal waveforms and frequencies are not drawn according to scale.

[0085] Figure 2A is a circuit schematic diagram of a switched-capacitor voltage conversion circuit according to an embodiment of the present disclosure. As shown in Figure 2A , the switched-capacitor voltage conversion circuit 20 is used to convert a first voltage V1 into a second voltage V2 or convert the second voltage V2 into the first voltage V1. The switched-capacitor voltage conversion circuit 20 includes a control circuit 201 and a switched-capacitor converter 202. The switched-capacitor converter 202 is coupled between the first voltage V1 and the second voltage V2. The control circuit 201 is used to generate a control signal to control the switched-capacitor converter 202 to convert the first voltage V1 into the second voltage V2 or convert the second voltage V2 into the first voltage V1. In the present embodiment, the control signal includes a charging operation signal GA and at least one discharging operation signal GB. The switched-capacitor converter 202 includes at least one capacitor C1 and C2, a plurality of switches Q1-Q7, and at least one inductor L. The plurality of switches Q1-Q7 are coupled with the at least one capacitor C1 and C2.

[0086] The control circuit 201 selects the ratio between the first voltage V1 and the second voltage V2 according to the level of the first voltage V1 and aims to maintain the second voltage V2 within a first predetermined range, and generates a control signal to convert the first voltage V1 into the second voltage V2; or the control circuit 201 selects the ratio between the first voltage V1 and the second voltage V2 according to the level of the second voltage V2 and aims to maintain the first voltage V1 within a second predetermined range, and generates a control signal to convert the second voltage V2 into the first voltage V1.

[0087] In the charging procedure of the resonance operation mode, the switching of the plurality of switches Q1-Q7 is controlled by the charging operation signal GA to make at least one of the capacitors C1 and C2 and the corresponding inductor L in series between the first voltage V1 and the second voltage V2 to form a charging path and operate in resonance. In at least one discharging procedure of the resonance operation mode, the switching of the plurality of switches Q1-Q7 is controlled by the discharging operation signal GB to make at least one of the capacitors C1 and C2 and the corresponding inductor L in series between the second voltage V2 and a direct current potential (in this embodiment, the direct current potential is the ground potential) to form a plurality of discharging paths and operate in resonance at the same time or in turn. In the resonance operation mode, the charging procedure and the at least one discharging procedure are repeatedly interleaved with each other to convert the first voltage V1 into the second voltage V2 or convert the second voltage V2 into the first voltage V1.

[0088] Please refer to Figure 2A In the resonance operation mode, the control circuit 201 can adjust the duty cycle of the charging operation signal GA and / or the discharging operation signal GB to make the inductor current IL flowing towards the second voltage V2 in a first state when part of the plurality of switches (for example, switches Q1-Q3 or switches Q4-Q7) are turned on, and make the inductor current IL flowing through the corresponding inductor L continue to flow through the current continuation path in at least one of the switches (for example, switches Q3 and Q7), such as but not limited to the conduction of the body diode, to make the inductor current IL flowing towards the second voltage V2 in a second state when none of the plurality of switches (for example, switches Q1-Q7) are turned on, so that the corresponding inductor L performs inductive power conversion switching between the first state and the second state.

[0089] In one embodiment, in the resonant operation mode, the first state is that the inductor current IL flowing toward the second voltage V2 is a resonant current. In one embodiment, the second state is that the inductor current IL flowing toward the second voltage V2 is a non-resonant current. In a preferred embodiment, the second state is that the inductor current IL flowing toward the second voltage V2 is a linear ramp current. For example, in the resonant operation mode and / or the inductive switching mode, the control circuit 201 adjusts the duty cycle of the charging operation signal GA and / or the discharging operation signal GB to cause the end of the inductor L to be connected to the DC potential via the body diode in at least one of the switches (e.g., switches Q3 and Q7) when none of the switches (e.g., switches Q1-Q7) is conducting, thereby causing the inductor current IL flowing toward the second voltage V2 to be a linear ramp current.

[0090] Referring again to Figure 2A , the switching capacitor converter 202 can also operate in an inductive switching mode. In the inductive switching mode, the control signals further include an inductive operation signal to control the switching of the plurality of switches (e.g., switches Q1-Q7). The switching of the plurality of switches is controlled by the inductive operation signal to cause the end of the inductor L (e.g., the left end of the inductor L) to be alternatively coupled to the first voltage VI or the DC potential (ground potential in this embodiment) to convert the first voltage VI to the second voltage V2 and maintain the second voltage V2 within a first predetermined range, or convert the second voltage V2 to the first voltage VI and maintain the first voltage VI within a second predetermined range. Figure 2A

[0091] Figure 2B is a signal waveform diagram showing the relevant signals of the switching capacitor voltage conversion circuit according to one embodiment of the present application. The second voltage V2, the second current I2, the inductor current IL, the capacitor current IC1, the drain-source voltage Vds1 of the switch Q1, the drain-source voltage Vds6 of the switch Q6, the charging operation signal GA, and the discharging operation signal GB are as shown in Figure 2B . As shown in Figure 2B , in the resonant operation mode, the charging operation signal GA and at least one of the discharging operation signals GB are each switched to an on level for a plurality of on periods, and the plurality of on periods do not overlap with each other, so that the charging procedure and at least one of the discharging procedures do not overlap with each other.

[0092] Figure 2C is a block diagram showing the control circuit of the switching capacitor voltage conversion circuit according to one embodiment of the present application. Please refer to Figure 2C and Figure 2A ​The control circuit 201 includes a current sensing circuit 2011, a control signal generation circuit 2012, and a voltage sensing circuit 2013. The current sensing circuit 2011 senses the current flowing through at least one inductor L to generate at least one current sensing signal Cd. The control signal generation circuit 2012 is coupled to the current sensing circuit 2011 and generates control signals, such as a charging operation signal GA and a discharging operation signal GB, based on the current sensing signal Cd. The voltage sensing circuit 2013 senses a second voltage V2 to generate a voltage sensing signal Vd. In the inductor switching mode, the control signal generation circuit 2012 also generates inductor operation signals, such as second-order inductor operation signals Gb21 and Gb22 (described in detail later) and / or third-order inductor operation signals Gb31 and Gb32 (described in detail later), based on the voltage sensing signal Vd.

[0093] Figure 3A This is a circuit diagram showing a switching capacitor voltage conversion circuit according to another embodiment of the present invention. Figure 3A The embodiments are similar to Figure 2A The embodiment differs in that, in this embodiment, switch Q5 is always on, while switches Q3 and Q7 are always off, causing the capacitor converter 202 to enter a 2-to-1 mode, i.e., the ratio of the first voltage V1 to the second voltage V2 is 2:1. In the charging procedure of the resonant operation mode, the switching of multiple switches Q1, Q2, Q4, and Q6 is controlled by the charging operation signal GA, so that at least one capacitor C1 and its corresponding inductor L are connected in series between the first voltage V1 and the second voltage V2 to form a charging path and resonant operation. In at least one discharging procedure of the resonant operation mode, the switching of multiple switches Q1, Q2, Q4, and Q6 is controlled by the discharging operation signal GB, so that at least one capacitor C1 and its corresponding inductor L are connected in series between the second voltage V2 and the DC potential to form a discharging path and resonant operation. The inductor current freewheeling method is similar to... Figure 2A The embodiment differs in that it achieves freewheeling by conducting the internal diodes of switches Q2 and Q6. In one embodiment, the control circuit 201 selects whether the switching capacitor converter 202 operates in a two-to-one mode or a three-to-one mode based on the first voltage V1, so as to maintain the second voltage V2 within a first predetermined range.

[0094] Figure 3B This is a schematic diagram of signal waveforms for a switching capacitor voltage conversion circuit according to an embodiment of the present invention. The signals include: second voltage V2, second current I2, inductor current IL, capacitor current IC1, drain-source voltage Vds1 of switch Q1, drain-source voltage Vds6 of switch Q6, charging operation signal GA, and discharging operation signal GB. Figure 3B As shown.

[0095] Figure 3Cis a circuit schematic diagram showing a switched-capacitor voltage conversion circuit according to yet another embodiment of the present application. Figure 3D is a circuit schematic diagram showing a switched-capacitor voltage conversion circuit according to yet another embodiment of the present application. Figure 3C and 3D the embodiment of Figure 3A is similar to the embodiment of , except that in the present embodiment, the control signals further include inductor operation signals, which include third-order inductor operation signals Gb31 and Gb32. In the third-order inductor switching mode, the switching of the plurality of switches (e.g., switches Q1, Q2, Q4, Q6) is controlled by the third-order inductor operation signals Gb31 and Gb32, and in the inductor switching mode, switches Q3 and Q7 are constantly non-conductive, so that the voltage at one end of at least one inductor L is periodically switched between the first voltage V1, one-half of the first voltage V1, and a direct-current potential (in the present embodiment, a ground potential), so as to convert the first voltage V1 into the second voltage V2.

[0096] Please also refer to Figure 3C , in the inductor switching mode, the control circuit 201 can adjust the duty cycle of the inductor operation signals Gb31 and Gb32, so that when some of the plurality of switches (e.g., switches Q1, Q2, or switches Q4, Q6) are conductive, the inductor current IL flowing toward the second voltage V2 is in a first state, and when none of the plurality of switches (e.g., switches Q1, Q2, Q4, Q6) are conductive, the inductor current IL flowing through the corresponding inductor L is continuous through the conduction of the body diode in at least one switch (e.g., switches Q2 and Q6), thereby causing the inductor current IL flowing toward the second voltage V2 to be in a second state, so that the corresponding inductor L performs inductive power conversion switching between the first state and the second state. In one embodiment, the first state is that the inductor current IL flowing toward the second voltage V2 is a non-resonant current. In a preferred embodiment, the first state is that the inductor current IL flowing toward the second voltage V2 is a triangular wave current. In one embodiment, the second state is that the inductor current IL flowing toward the second voltage V2 is a non-resonant current. In a preferred embodiment, the second state is that the inductor current IL flowing toward the second voltage V2 is a linear ramp current.

[0097] For example, when the second voltage V2 is between the first voltage V1 and one-half of the first voltage V1, as shown in Figure 3C , the switching of the plurality of switches Q1, Q2, Q4, Q6 is controlled by the third-order inductor operation signal Gb32, so that at least one capacitor C1 and the corresponding inductor L are connected in series between the second voltage V2 and the direct-current potential, and as shown in Figure 3DAs shown, the switching of the plurality of switches Q1, Q2, Q4, Q6 is then controlled by the third-order inductor operation signal Gb31 to couple one end of the inductor L to the first voltage V1, thereby periodically switching the voltage at one end of the inductor L between the first voltage V1 and one-half of the first voltage V1. In another embodiment, when the second voltage V2 is between 0 and one-half of the first voltage V1, as shown, the switching of the plurality of switches Q1, Q2, Q4, Q6 is controlled by the third-order inductor operation signal Gb31 to couple one end of the inductor L to the second voltage V2, thereby periodically switching the voltage at one end of the inductor L between the second voltage V2 and one-half of the first voltage V1. Figure 3C As shown, the switching of the plurality of switches Q1, Q2, Q4, Q6 is controlled by the third-order inductor operation signal Gb31 to couple at least one capacitor C1 and a corresponding inductor L in series between the first voltage V1 and the second voltage V2, and as shown, the switching of the plurality of switches Q1, Q2, Q4, Q6 is controlled by the third-order inductor operation signal Gb31 to couple at least one capacitor C1 and a corresponding inductor L in series between the first voltage V1 and the second voltage V2. Figure 3D As shown, the switching of the plurality of switches Q1, Q2, Q4, Q6 is then controlled by the third-order inductor operation signal Gb32 to couple one end of the inductor L to a DC potential (in this embodiment, the ground potential), thereby periodically switching the voltage at one end of the inductor L between 0 and one-half of the first voltage V1. Figure 3D The inductor current freewheeling manner of this embodiment is similar to that of the embodiment of Figure 3C Please refer to the relevant description of Figure 3C

[0098] Figure 4 is a circuit schematic diagram showing a switched-capacitor voltage conversion circuit according to yet another embodiment of the present application. This embodiment is similar to the embodiment of Figure 2A except that the switches Q2, Q5 and Q6 are always non-conductive. In this embodiment, the control signals further include second-order inductor operation signals Gb21 and Gb22. In the second-order inductor switching mode (which can also be referred to as the inductor switching mode), the switching of the plurality of switches Q1, Q3, Q4, Q7 is controlled by the second-order inductor operation signals Gb21 and Gb22 to alternately (periodically) couple one end of at least one inductor L to the first voltage V1 or a DC potential, so as to convert the first voltage V1 into the second voltage V2. In one embodiment, the control circuit 201 selects one of the second-order inductor switching mode, the two-to-one mode, the three-to-one mode and the third-order inductor switching mode for the switched-capacitor converter 202 to operate in, according to the first voltage V1, so as to maintain the second voltage V2 within the first predetermined range. In another embodiment, the control circuit 201 selects one of the second-order inductor switching mode, the two-to-one mode and the three-to-one mode for the switched-capacitor converter 202 to operate in, according to the first voltage V1, so as to maintain the second voltage V2 within the first predetermined range. The inductor current freewheeling manner of this embodiment is similar to that of the embodiment of Figure 3C Please refer to the relevant description of Figure 3C except that the inductor current freewheeling is achieved by the conduction of the internal diodes of the switches Q3 and Q7 in this embodiment.

[0099] Figure 5 ​is a circuit schematic diagram showing a switched-capacitor voltage conversion circuit according to yet another embodiment of the present application. This embodiment is similar to the embodiment of Figure 4 , please refer to the relevant descriptions of Figure 4 , except that switches Ql and Q6 are always on, and the operation signals Gb21 and Gb22 only control the switching of switches Q4, Q3 and Q7, so that one end of at least one inductor L is alternately (periodically) coupled to the first voltage VI or the DC potential, and so that capacitor Cl can serve as an input capacitor. The inductor current freewheeling manner of this embodiment is similar to the embodiment of Figure 4 , please refer to the relevant descriptions of Figure 4 .

[0100] Figure 6 is an operation mode characteristic diagram showing a switched-capacitor voltage conversion circuit according to an embodiment of the present application. Please refer to Figure 6 , Figure 2A and Figure 3A , the control circuit 201 selects one of the operation modes of the switched-capacitor converter 202 according to the magnitude of the first voltage VI, so as to maintain the second voltage V2 within a first predetermined range (between voltage V21 and voltage V22), for example. As shown in Figure 6 , the control circuit 201 switches the operation mode in a hysteresis manner, when the first voltage VI is greater than a first threshold Vthl, the control circuit 201 causes the switched-capacitor converter 202 to operate in a three-to-one mode. When the first voltage VI is less than a second threshold Vth2, the control circuit 201 causes the switched-capacitor converter 202 to operate in a two-to-one mode.

[0101] Figure 7 is an operation mode characteristic diagram showing a switched-capacitor voltage conversion circuit according to another embodiment of the present application. Please refer to Figure 7 , Figure 2A , Figure 3A , Figure 3C , Figure 3D , Figure 4 and Figure 5 , the control circuit 201 selects one of the operation modes of the switched-capacitor converter 202 according to the magnitude of the first voltage VI, so as to maintain the second voltage V2 within a first predetermined range (between voltage V21 and voltage V22), for example. As shown in Figure 7As shown, when the first voltage V1 is greater than the first threshold Vth1, the control circuit 201 causes the switched capacitor converter 202 to operate in the second-order inductive switching mode or the third-order inductive switching mode. When the first voltage V1 is less than the second threshold Vth2 and greater than the third threshold Vth3, the control circuit 201 causes the switched capacitor converter 202 to operate in the three-to-one mode. When the first voltage V1 is less than the fourth threshold Vth4 and greater than the fifth threshold Vth5, the control circuit 201 causes the switched capacitor converter 202 to operate in the two-to-one mode. When the first voltage V1 is less than the sixth threshold Vth6, the control circuit 201 causes the switched capacitor converter 202 to operate in the second-order inductive switching mode or the third-order inductive switching mode.

[0102] Figure 8 FIG. 6 is a circuit schematic diagram showing a switched capacitor voltage conversion circuit according to yet another embodiment of the present application. As shown, the switched capacitor converter 602 of the switched capacitor voltage conversion circuit 60 of the present embodiment comprises capacitors C1-C3, switches Q1-Q10, and an inductor L. Switches Q1-Q3 are connected in series with corresponding capacitors C1-C3, respectively, while switch Q4 is connected in series with the inductor L. Figure 8

[0103] The switches Q1-Q10 can switch the electrical connection relationship of the corresponding capacitors C1-C3 and the inductor L according to corresponding operation signals. In the charging program, according to the charging operation signal GA, switches Q1-Q4 are turned on, and switches Q5-Q10 are turned off, so that the capacitors C1-C3 are connected in series with each other and then connected in series with the inductor L between the first voltage V1 and the second voltage V2 to form a charging path. In the discharging program, according to the discharging operation signal GB, switches Q5-Q10 are turned on, and switches Q1-Q4 are turned off, so that the capacitors C1-C3 are connected in parallel with each other and then connected in series with the inductor L between the second voltage V2 and the ground potential to form a plurality of discharging paths. It should be noted that the above charging program and the above discharging program are repeatedly interleaved at different time periods instead of being performed simultaneously to convert the first voltage V1 to the second voltage V2 or convert the second voltage V2 to the first voltage V1. In the present embodiment, the DC bias of each of the capacitors C1-C3 is the second voltage V2, so the capacitors C1-C3 in the present embodiment need to withstand a lower rated voltage, and therefore a smaller volume capacitor can be used.

[0104] The control circuit 601 and the operation mode of the present embodiment can be implemented similarly to the control circuit architecture and the operation mode of the control circuit of Figure 2A , Figure 2C , Figure 3A , Figure 3C , Figure 3D , Figure 4 and Figure 5 Please refer to the description of the control circuit architecture and the operation mode of the control circuit of Figure 2A , Figure 2C , Figure 3A ,​Figure 3C , Figure 3D , Figure 4 and Figure 5 Please refer to the detailed descriptions of Figure 2A if operated in four-to-one mode, Figure 3A if operated in three-to-one mode or two-to-one mode, Figure 3C if operated in three-stage inductive switching mode, and Figure 3D if operated in two-stage inductive switching mode, respectively. Figure 4 Figure 5 Please refer to the detailed descriptions of Figure 2A , Figure 3A , Figure 3C , Figure 3D , Figure 4 and Figure 5 respectively.

[0105] Figure 9 is a circuit schematic diagram of a switching-capacitor voltage conversion circuit according to another embodiment of the present application. As shown in Figure 9 , the switching-capacitor converter 702 of the switching-capacitor voltage conversion circuit 70 of the present application comprises capacitors C1-C4, switches Q1-Q13, and an inductor L. The switches Q1-Q4 are connected in series with the corresponding capacitors C1-C4 respectively, and the switch Q5 is connected in series with the inductor L.

[0106] The switches Q1-Q13 can switch the electrical connection relationship between the corresponding capacitors C1-C4 and the inductor L according to the corresponding operation signals. In the charging program, according to the charging operation signal GA, the switches Q1-Q5 are turned on and the switches Q6-Q13 are turned off, so that the capacitors C1-C4 are connected in series with each other and then connected in series with the inductor L between the first voltage V1 and the second voltage V2 to form a charging path. In the discharging program, according to the discharging operation signal GB, the switches Q6-Q13 are turned on and the switches Q1-Q5 are turned off, so that the capacitors C1-C4 are connected in parallel with each other and then connected in series with the inductor L between the second voltage V2 and the ground potential to form a plurality of discharging paths. It should be noted that the above charging program and the above discharging program are repeatedly interleaved at different time periods instead of being performed simultaneously, so as to convert the first voltage V1 into the second voltage V2 or convert the second voltage V2 into the first voltage V1. In the present embodiment, the DC bias of each capacitor C1-C4 is the second voltage V2, so the capacitors C1-C4 in the present embodiment need to withstand a lower rated voltage, and therefore a smaller volume capacitor can be used.

[0107] The control circuit 701 and the operation mode of the present embodiment can be similar to Figure 2A , Figure 2C , Figure 3A , Figure 3C , Figure 3D , Figure 4 ​and Figure 5 The control circuit architecture and operation method should be implemented accordingly. Please refer to the relevant documentation. Figure 2A , Figure 2C , Figure 3A , Figure 3C , Figure 3D , Figure 4 and Figure 5 A detailed description. The inductor current freewheeling mode, if operated in a 5-to-1 conversion mode, is similar to... Figure 2A If the operation is in four-to-one, three-to-one, or two-to-one mode, it is similar to Figure 3A If the operation is in third-order inductor switching mode, it is similar to Figure 3C and Figure 3D If the operation is in second-order inductor switching mode, it is similar to Figure 4 and Figure 5 Please refer to the relevant information respectively. Figure 2A , Figure 3A , Figure 3C , Figure 3D , Figure 4 and Figure 5 A detailed description.

[0108] As described above, the present invention provides a switching capacitor voltage conversion circuit, which, by combining an N-to-1 mode and a second- or third-order inductor switching mode and allowing the inductor current to freewheel, enables the second voltage (or output voltage) to have a smaller variation range, provides more operating modes with different voltage conversion ratios, and achieves automatic mode switching control between multiple operating modes of a resonant switching capacitor converter.

[0109] The circuit described above for converting a first voltage V1 to a second voltage V2 is also applicable to converting a second voltage V2 to a first voltage V1. The control circuit selects the ratio between the first voltage V1 and the second voltage V2 based on the level of the second voltage V2, with the goal of maintaining the first voltage V1 within a second predetermined range, and generates a control signal to convert the second voltage V2 to the first voltage V1. Specifically, the control circuit 201 selects one of the following modes based on the first voltage V1: a two-to-one conversion mode, a three-to-one conversion mode, and an inductor switching mode, to maintain the second voltage V2 within the first predetermined range. Similarly, the circuit can also be configured such that the control circuit 201 selects one of the following modes based on the second voltage V2: a one-to-two conversion mode, a one-to-three conversion mode, and an inductor switching mode, to maintain the first voltage V1 within the second predetermined range.

[0110] The above has been described for the preferred embodiments of the present application, but the above description is only for the purpose of making those skilled in the art easily understand the content of the present application, and is not intended to limit the broadest scope of the present application. The various embodiments described are not limited to separate applications, but can also be combined, for example, two or more embodiments can be combined, and part of the components in one embodiment can also be used to replace the corresponding components in another embodiment. In addition, various equivalent changes and various combinations can be conceived by those skilled in the art in the same spirit of the present application, for example, the present application refers to "processing or operating or generating an output result according to a certain signal", which is not limited to processing or operating or generating an output result according to the signal itself, but also includes, if necessary, voltage-current conversion, current-voltage conversion, and / or scaling conversion, etc., and then processing or operating or generating an output result according to the converted signal. Therefore, it can be seen that various equivalent changes and various combinations can be conceived by those skilled in the art in the same spirit of the present application, and the combination methods are various, which are not listed one by one here. Therefore, the scope of the present application should cover all the above and other equivalent changes.

Claims

1. A switching capacitor voltage conversion circuit for converting a first voltage to a second voltage or converting the second voltage to the first voltage, characterized in that, The switching capacitor voltage conversion circuit comprises: a switching capacitor converter coupled between the first voltage and the second voltage; and a control circuit configured to generate a control signal to control the switching capacitor converter to convert the first voltage to the second voltage or to convert the second voltage to the first voltage; wherein the switching capacitor converter comprises: at least one capacitor; a plurality of switches coupled to the at least one capacitor; and at least one inductor; wherein the control circuit is configured to select a ratio between the first voltage and the second voltage according to a level of the first voltage and with a target of maintaining the second voltage within a first predetermined range, and to generate the control signal to convert the first voltage to the second voltage, or to select the ratio between the first voltage and the second voltage according to a level of the second voltage and with a target of maintaining the first voltage within a second predetermined range, and to generate the control signal to convert the second voltage to the first voltage; wherein the control signal comprises a charging operation signal and at least one discharging operation signal; wherein in a charging procedure of a resonant operation mode, the plurality of switches are controlled by the charging operation signal to make the at least one capacitor and a corresponding inductor in series between the first voltage and the second voltage to form a charging path and to operate in resonance; wherein in at least one discharging procedure of the resonant operation mode, the plurality of switches are controlled by the at least one discharging operation signal to make the at least one capacitor and a corresponding inductor in series between the second voltage and a DC potential to form or alternately form a plurality of discharging paths and to operate in resonance; wherein in the resonant operation mode, the charging operation signal and the at least one discharging operation signal are each switched to an on level for a plurality of on periods, and the plurality of on periods do not overlap with each other, so that the charging procedure and the at least one discharging procedure do not overlap with each other; wherein in the resonant operation mode, the charging procedure and the at least one discharging procedure are repeatedly interleaved to convert the first voltage to the second voltage or to convert the second voltage to the first voltage; wherein the at least one capacitor comprises N capacitors, and the resonant operation mode comprises an M-to-one mode, wherein in the M-to-one mode, the ratio between the first voltage and the second voltage is M times, wherein N is a natural number greater than or equal to 2, and M is a natural number greater than or equal to 2 and less than or equal to N+1; wherein the control circuit is configured to determine a value of M according to the first voltage or the second voltage, and to select the switching capacitor converter to operate in the M-to-one mode; wherein in the M-to-one mode, the control circuit controls the plurality of switches to make M-1 capacitors and a corresponding single inductor to form the charging path and the discharging path in the charging procedure and the discharging procedure, respectively, and to operate in resonance.

2. The switched-capacitor voltage conversion circuit of claim 1, wherein, The control signal further includes an inductive operation signal to control switching of the plurality of switches to operate the switched-capacitor converter in an inductive switching mode to alternately couple one end of the at least one inductor to the first voltage or the DC potential to convert the first voltage to the second voltage and maintain the second voltage within the first predetermined range or convert the second voltage to the first voltage and maintain the first voltage within the second predetermined range.

3. The switched-capacitor voltage conversion circuit of claim 2, wherein, In the resonant operation mode and / or the inductive switching mode, the control circuit adjusts duty cycles of the charging operation signal and / or the discharging operation signal and / or the inductive operation signal to cause an inductive current flowing toward the second voltage to be in a first state when some of the plurality of switches are turned on and to cause the inductive current flowing through the corresponding inductor to freewheel through at least one current freewheeling path when none of the plurality of switches are turned on, thereby causing the inductive current flowing toward the second voltage to be in a second state, so that the corresponding inductor performs inductive power conversion switching between the first state and the second state.

4. The switched-capacitor voltage conversion circuit of claim 2, wherein, The control circuit is configured to select one of the M-to-one mode and the inductive switching mode to operate the switched-capacitor converter to convert the first voltage to the second voltage and maintain the second voltage within the first predetermined range or convert the second voltage to the first voltage and maintain the first voltage within the second predetermined range according to the first voltage or the second voltage.

5. The switched-capacitor voltage conversion circuit of claim 4, wherein, The inductive switching mode includes a second-order inductive switching mode and / or a third-order inductive switching mode, and the inductive operation signal includes a second-order inductive operation signal and / or a third-order inductive operation signal. In the second-order inductive switching mode, the second-order inductive operation signal controls switching of the plurality of switches to cause the voltage of the one end of the at least one inductor to periodically switch between the first voltage and the DC potential to convert the first voltage to the second voltage or convert the second voltage to the first voltage. In the third-order inductive switching mode, the third-order inductive operation signal controls switching of the plurality of switches to cause the voltage of the one end of the at least one inductor to periodically switch between the first voltage, one-half of the first voltage, and the DC potential to convert the first voltage to the second voltage or convert the second voltage to the first voltage.

6. The switched-capacitor voltage conversion circuit of claim 5, wherein, The control circuit is configured to select one of the M-to-one mode, the second-order inductive switching mode, and the third-order inductive switching mode to maintain the second voltage within the first predetermined range or maintain the first voltage within the second predetermined range according to the first voltage or the second voltage.

7. The switched-capacitor voltage conversion circuit of claim 1, wherein, The switched-capacitor converter includes a series-parallel switched-capacitor converter.

8. The switched-capacitor voltage conversion circuit of claim 7, wherein, The series-parallel switched-capacitor converter includes an M-to-one series-parallel switched-capacitor converter.

9. The switched-capacitor voltage conversion circuit of claim 1, wherein, The DC potential is a ground potential.

10. The switched-capacitor voltage conversion circuit of claim 2, wherein, The control circuit includes: a current sensing circuit configured to sense a current flowing through the at least one inductor to generate at least one current sensing signal; and a control signal generation circuit coupled to the current sensing circuit and configured to generate the control signal according to the current sensing signal.

11. The switched-capacitor voltage conversion circuit of claim 10, wherein, The control circuit further includes a voltage sensing circuit for sensing the second voltage or the first voltage to generate a voltage sensing signal, wherein the control signal generating circuit generates the inductor operation signal according to the voltage sensing signal in the inductor switching mode.

12. A switched-capacitor voltage conversion method for converting a first voltage to a second voltage or a second voltage to a first voltage of a switched-capacitor converter, the switched-capacitor converter comprising at least one capacitor, a plurality of switches, and at least one inductor, the method comprising: The switched-capacitor voltage conversion method includes: According to the level of the first voltage, and with the goal of maintaining the second voltage within a first predetermined range, the ratio between the first voltage and the second voltage is selected to generate a control signal to convert the first voltage to the second voltage, or according to the level of the second voltage, and with the goal of maintaining the first voltage within a second predetermined range, the ratio between the first voltage and the second voltage is selected to generate the control signal to convert the second voltage to the first voltage; In a charging program of a resonance operation mode, the switching of the plurality of switches is controlled by a charging operation signal to make the at least one capacitor and the corresponding inductor in series between the first voltage and the second voltage to form a charging path and operate in resonance; In at least one discharging program of the resonance operation mode, the switching of the plurality of switches is controlled by at least one discharging operation signal to make the at least one capacitor and the corresponding inductor in series between the second voltage and a direct current potential to simultaneously or alternately form a plurality of discharging paths and operate in resonance; In the resonance operation mode, the charging operation signal and the at least one discharging operation signal are each switched to an on state for an on period, and the plurality of on periods do not overlap with each other, so that the charging program and the at least one discharging program do not overlap with each other; In the resonance operation mode, the charging program and the at least one discharging program are repeatedly interleaved to convert the first voltage to the second voltage or convert the second voltage to the first voltage; The at least one capacitor includes N capacitors, and the resonance operation mode includes an M-to-one mode, in which the ratio between the first voltage and the second voltage is M times, where N is a natural number greater than or equal to 2, and M is a natural number greater than or equal to 2 and less than or equal to N+1; The step of generating the control signal includes determining the value of M according to the first voltage or the second voltage, and selecting the ratio between the first voltage and the second voltage to operate the switched-capacitor converter in the M-to-one mode; In the M-to-one mode, the control signal is used to control the plurality of switches in the charging program and the discharging program, so that M-1 capacitors and a single inductor correspondingly form the charging path and the discharging path and operate in resonance.

13. The switched-capacitor voltage conversion method of claim 12, wherein, Further comprising: in an inductor switching mode, the switching of the plurality of switches is controlled by an inductor operation signal to alternately couple one end of the at least one inductor to the first voltage or the direct current potential to convert the first voltage to the second voltage and maintain the second voltage within the first predetermined range, or convert the second voltage to the first voltage and maintain the first voltage within the second predetermined range.

14. The switched-capacitor voltage conversion method of claim 13, wherein, Further comprising: In the resonant operation mode and / or the inductive switching mode, duty cycles of the charging operation signal and / or the discharging operation signal and / or the inductive operation signal are adjusted so that an inductive current flowing toward the second voltage is in a first state when some of the switches are turned on, and the inductive current flowing through the corresponding inductor is freewheeled through at least one freewheeling path when none of the switches are turned on, so that the inductive current flowing toward the second voltage is in a second state, so that the corresponding inductor performs inductive power conversion switching between the first state and the second state.

15. The switched-capacitor voltage conversion method of claim 13, wherein, The step of generating the control signal further comprises: selecting one of the M-to-1 mode and the inductive switching mode for the switched-capacitor converter to convert the first voltage to the second voltage and maintain the second voltage within the first predetermined range, or convert the second voltage to the first voltage and maintain the first voltage within the second predetermined range, according to the first voltage or the second voltage.

16. The switched-capacitor voltage conversion method of claim 15, wherein, The inductive switching mode comprises a second-order inductive switching mode and / or a third-order inductive switching mode, and the inductive operation signal comprises a second-order inductive operation signal and / or a third-order inductive operation signal. In the second-order inductive switching mode, the switching of the switches is controlled by the second-order inductive operation signal to periodically switch the voltage at the end of the at least one inductor between the first voltage and the DC potential, so as to convert the first voltage to the second voltage or convert the second voltage to the first voltage. In the third-order inductive switching mode, the switching of the switches is controlled by the third-order inductive operation signal to periodically switch the voltage at the end of the at least one inductor between the first voltage, half of the first voltage, and the DC potential, so as to convert the first voltage to the second voltage or convert the second voltage to the first voltage.

17. The switched-capacitor voltage conversion method of claim 16, wherein, The step of generating the control signal further comprises: selecting one of the M-to-1 mode, the second-order inductive switching mode, and the third-order inductive switching mode for the switched-capacitor converter to maintain the second voltage within the first predetermined range or maintain the first voltage within the second predetermined range, according to the first voltage or the second voltage.

18. The switched-capacitor voltage conversion method of claim 12, wherein, The switched-capacitor converter comprises a series-parallel switched-capacitor converter.

19. The switched-capacitor voltage conversion method of claim 18, wherein, The series-parallel switched-capacitor converter comprises an M-to-1 series-parallel switched-capacitor converter.

20. The switched-capacitor voltage conversion method of claim 12, wherein, The DC potential is a ground potential.

21. The switched-capacitor voltage conversion method of claim 13, wherein, Further comprising: sensing a current flowing through the at least one inductor to generate at least one current sensing signal; and generating the charging operation signal, the at least one discharging operation signal, and the inductive operation signal according to the current sensing signal.

22. The switched-capacitor voltage conversion method of claim 21, wherein, Further comprising: sensing the second voltage or the first voltage to generate a voltage sensing signal, and generating the inductive operation signal according to the voltage sensing signal in the inductive switching mode.

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