TWI868783B - Multi-phase switching converter and control method thereof - Google Patents

Abstract

The present invention provides a multi-phase switching converter, including: plural sub-switching converters; and a control circuit; wherein plural switching signals operate a capacitor of one of the plural sub-switching converters and a capacitor of another of the plural sub-switching converters to perform a switched capacitor switching to a first voltage among plural electrical connection states, so as to switch an inductor switching node inside one of the plural sub-switching converters between a divided voltage of the first voltage and a reference voltage level, such that a power conversion between the first voltage and a second voltage can be performed; wherein when the inductors of each of the plural sub-switching converters are not electromagnetically coupled with one another, the multi-phase switching converters operate in a non-resonant mode; wherein when the inductors of at least two of the plural sub-switching converters are electromagnetically coupled with one another, the multi-phase switching converters operate in a resonant mode or in the non-resonant mode.

Description

Multi-phase conversion circuit and control method thereof

The present invention relates to a multi-phase conversion circuit and a control method thereof, and more particularly to a multi-phase conversion circuit and a control method thereof that can achieve a smaller inductor size.

FIG. 1 is a circuit diagram showing a known two-phase conversion circuit. As shown in FIG. 1 , the known two-phase conversion circuit 10 includes two buck conversion circuits 101a and 101b, which are coupled in parallel to each other to extend the output current. The known two-phase conversion circuit 10 requires switches Q1~Q4 with high rated voltages to withstand the maximum voltage of the input voltage Vin. And because the voltage across the inductors L1 and L2 is very high, the inductors L1 and L2 need to have high inductance values, so the sizes of the inductors L1 and L2 will be quite large.

In view of this, the present invention proposes a multi-phase conversion circuit and a control method thereof that can achieve a smaller inductor size.

In one aspect, the present invention provides a multi-phase conversion circuit for performing power conversion between a first voltage at a first node and a second voltage at a second node, the multi-phase conversion circuit comprising: a plurality of sub-conversion circuits; and a control circuit for generating a plurality of switching signals to correspond to a plurality of switches of the plurality of sub-conversion circuits, and periodically switching the plurality of sub-conversion circuits between a plurality of electrical connection states to perform power conversion between the first voltage and the second voltage; wherein each of the plurality of sub-conversion circuits comprises a capacitor, an inductor and a portion of the plurality of switches, and one end of the inductor is coupled to the second node, and the other end of the inductor is coupled to the capacitor at An inductor switching node inside the sub-conversion circuit where it is located; wherein the plurality of switching signals, between the plurality of electrical connection states, operate the capacitor of one of the sub-conversion circuits in the plurality of sub-conversion circuits and the capacitor of another sub-conversion circuit in the plurality of sub-conversion circuits to perform capacitive switching on the first voltage, so as to switch the inductor switching node inside one of the plurality of sub-conversion circuits between a voltage division of the first voltage and a reference potential, thereby performing power conversion between the first voltage and the second voltage; wherein when the inductors of each of the plurality of sub-conversion circuits are non-electromagnetic coupling (non-electromagnetic coupling) with each other The multi-phase conversion circuit operates in a non-resonant mode; when at least two of the inductors in the multi-phase conversion circuit are electromagnetically coupled to each other, the multi-phase conversion circuit operates in a resonant mode or the non-resonant mode.

In another aspect, the present invention provides a multi-phase conversion circuit control method, the multi-phase conversion circuit control method comprising: generating a plurality of switching signals to correspond to a plurality of switches of a plurality of sub-conversion circuits of a multi-phase conversion circuit, and periodically switching the plurality of sub-conversion circuits between a plurality of electrical connection states to perform power conversion between a first voltage of a first node and a second voltage of a second node, wherein each of the plurality of sub-conversion circuits comprises a capacitor, an inductor and part of the plurality of switches, and one end of the inductor is coupled to the second node, and the other end of the inductor and the capacitor are coupled to the inside of the sub-conversion circuit where the inductor is located. an inductor switching node; and the plurality of switching signals operate the capacitor of one of the plurality of sub-conversion circuits and the capacitor of another sub-conversion circuit in the plurality of sub-conversion circuits to perform capacitive switching on the first voltage between the plurality of electrical connection states, so as to switch the inductor switching node inside one of the plurality of sub-conversion circuits between a divided voltage of the first voltage and a reference potential, thereby performing power conversion between the first voltage and the second voltage; wherein when the inductors of each of the plurality of sub-conversion circuits are non-electromagnetic coupling (non-electromagnetic coupling) with each other, The multi-phase conversion circuit operates in a non-resonant mode; when at least two of the inductors in the multi-phase conversion circuit are electromagnetically coupled to each other, the multi-phase conversion circuit operates in a resonant mode or the non-resonant mode.

In one embodiment, at least two inductor currents of at least two of the at least two inductors in the multiple sub-conversion circuit have a phase difference.

In one embodiment, the minimum number of the voltage divider is 1, and the maximum number is the number of the plurality of sub-conversion circuits minus 1.

In one embodiment, the plurality of sub-conversion circuits periodically switch two of the sub-conversion circuits in a continuous sequence between the plurality of electrical connection states in a ring sequence to switch the inductor switching node between a half-divided voltage of the first voltage and the reference potential, thereby performing power conversion between the first voltage and the second voltage.

In one embodiment, the number of the plurality of sub-conversion circuits is N, and all the sub-conversion circuits in a continuous sequence are periodically switched between the plurality of electrical connection states in a circular sequence, so that all the inductance switching nodes of all the sub-conversion circuits are correspondingly switched to the 1/N voltage division, the 2/N voltage division, and so on to the N/N-1 voltage division and the reference potential, thereby performing power conversion between the first voltage and the second voltage, wherein N is a positive integer greater than 2.

In one embodiment, the plurality of switches of one of the plurality of sub-conversion circuits include: a bridge switch coupled between the first node and the capacitor of the sub-conversion circuit in which it is located; a bridge switch coupled between the inductor switching node of the sub-conversion circuit in which it is located and the reference potential; and a jumper switch coupled between a capacitor switching node between the bridge switch and the capacitor of the sub-conversion circuit in which it is located and the inductor switching node of another of the plurality of sub-conversion circuits.

In one embodiment, the multi-phase conversion circuit further includes an auxiliary switching capacitor circuit, the auxiliary switching capacitor circuit is coupled to the one sub-conversion circuit and the other sub-conversion circuit, and the auxiliary switching capacitor circuit includes an auxiliary capacitor and a plurality of auxiliary switches; wherein the control circuit further generates a plurality of auxiliary switching signals to correspondingly control the plurality of auxiliary switches of the auxiliary switching capacitor circuit and the plurality of switches of the one sub-conversion circuit and the other sub-conversion circuit, and periodically switches the auxiliary capacitor and the one sub-conversion circuit and the other sub-conversion circuit between a first auxiliary electrical connection state and a second auxiliary electrical connection state. states to perform the switching capacitor voltage conversion of the first voltage, and adjust the capacitance bias of the auxiliary capacitor to an auxiliary voltage division of the first voltage; wherein the first auxiliary electrical connection state includes the capacitor of one of the sub-conversion circuits and the capacitor of the other sub-conversion circuit being connected in series with the auxiliary capacitor and then connected in parallel between an auxiliary switching node inside the auxiliary switching capacitor circuit and the reference potential; wherein the second auxiliary electrical connection state includes the capacitor of one of the sub-conversion circuits and the capacitor of the other sub-conversion circuit being connected in series with the auxiliary capacitor and then connected in series between the first node and the reference potential.

In one embodiment, the control circuit further generates the switching signal to switch the corresponding switch to switch the electrical connection state after a zero current detection signal indicates that an inductor current flowing through the corresponding inductor is zero current at a zero current point in time.

In one embodiment, the control circuit generates the switching signal after waiting for a dead-time after the zero current point to switch the corresponding switch to switch the electrical connection state.

In one embodiment, the corresponding plurality of switches achieves soft switching of zero current switching (ZCS) and/or zero voltage switching (ZVS).

In one embodiment, the control circuit generates the switching signal to switch the corresponding switch according to the first voltage, the second voltage and a load level to switch the electrical connection state and magnetize the inductor at a fixed conduction time.

In one embodiment, the control circuit generates the switching signal according to a load level to switch the corresponding switch to switch the electrical connection state, and enables the multiple sub-conversion circuit to operate in a boundary conduction mode (BCM), a continuous conduction mode (CCM) or a discontinuous conduction mode (DCM).

In one embodiment, the control circuit switches the corresponding switch to switch the electrical connection state after the corresponding inductor is demagnetized and an inductor current flowing through the inductor becomes zero current, then waits for a delay time.

In one embodiment, the control circuit includes a zero current detection circuit. When the inductor current flowing through the corresponding inductor is zero current, the zero current detection circuit generates a zero current detection signal to switch the corresponding switch.

In one embodiment, when the multi-phase conversion circuit operates in the resonance mode, when the control circuit detects that an inductor current flowing through the inductor is zero current, a zero current detection signal is generated to switch the corresponding switch.

In one embodiment, the multi-phase conversion circuit control method further includes: the plurality of switching signals periodically switches two of the consecutive sub-conversion circuits in the plurality of sub-conversion circuits in a ring sequence between the plurality of electrical connection states, so as to switch the inductor switching node between the half-divided voltage of the first voltage and the reference potential, thereby performing power conversion between the first voltage and the second voltage.

In one embodiment, the number of the plurality of sub-conversion circuits is N, and the multi-phase conversion circuit control method further includes: the plurality of switching signals periodically switches all the sub-conversion circuits in a continuous sequence in the plurality of sub-conversion circuits according to a ring sequence between the plurality of electrical connection states, so as to switch all the inductance switching nodes of all the sub-conversion circuits to one-Nth voltage division, two-Nth voltage division, and so on to between Nth-1th voltage division and the reference potential, thereby performing power conversion between the first voltage and the second voltage, wherein N is a positive integer greater than 2.

In one embodiment, the multi-phase conversion circuit control method further includes: generating a plurality of auxiliary switching signals to correspond to controlling a plurality of auxiliary switches of an auxiliary switching capacitive circuit and the plurality of switches of one of the sub-conversion circuits and the other sub-conversion circuit, and periodically switching an auxiliary capacitor of the auxiliary switching capacitive circuit and the one of the sub-conversion circuits and the other sub-conversion circuit between a first auxiliary electrical connection state and a second auxiliary electrical connection state to perform the switching capacitive voltage conversion of the first voltage, and adjusting the capacitance bias of the auxiliary capacitor to an auxiliary voltage of the first voltage. Voltage division, wherein the auxiliary switching capacitive circuit is coupled to one of the sub-conversion circuits and the other sub-conversion circuit; wherein the first auxiliary electrical connection state includes the capacitor of one of the sub-conversion circuits and the capacitor of the other sub-conversion circuit being connected in series and then connected in parallel with the auxiliary capacitor between an auxiliary switching node inside the auxiliary switching capacitive circuit and the reference potential; wherein the second auxiliary electrical connection state includes the capacitor of one of the sub-conversion circuits and the capacitor of the other sub-conversion circuit being connected in series and then connected in series with the auxiliary capacitor between the first node and the reference potential.

In one embodiment, the multi-phase conversion circuit control method further includes: generating the switching signal after a zero current time point indicating that an inductor current flowing through the corresponding inductor is zero current according to a zero current detection signal, so as to switch the corresponding switch to switch the electrical connection state.

In one embodiment, the multi-phase conversion circuit control method further includes: after the zero current point, after waiting for a dead-time, generating the switching signal to switch the corresponding switch to switch the electrical connection state.

In one embodiment, the switching signal is generated according to the first voltage, the second voltage and a load level to switch the corresponding switch to switch the electrical connection state and magnetize the inductor at a fixed conduction time.

In one embodiment, the switching signal is generated according to a load level to switch the corresponding switch to switch the electrical connection state and enable the multi-subconverter circuit to operate in a boundary conduction mode (BCM), a continuous conduction mode (CCM) or a discontinuous conduction mode (DCM).

In one embodiment, the multi-phase conversion circuit control method further includes: after the corresponding inductor is demagnetized and an inductor current flowing through the inductor becomes zero current, wait for a delay time, and switch the corresponding switch to switch the electrical connection state.

In one embodiment, the multi-phase conversion circuit control method further includes: when an inductor current flowing through the corresponding inductor is zero current, a zero current detection signal is generated to switch the corresponding switch.

In one embodiment, the multi-phase conversion circuit control method further includes: when the multi-phase conversion circuit operates in the resonance mode, when it is detected that an inductor current flowing through the inductor is zero current, a zero current detection signal is generated to switch the corresponding switch.

The advantage of the present invention is that the multi-phase conversion circuit of the present invention can achieve higher power conversion efficiency, smaller inductor size and generate lower voltage stress on components.

The following detailed description is based on specific embodiments, which will make it easier to understand the purpose, technical content, features and effects of the present invention.

The diagrams in this invention are schematic, and are mainly intended to show the coupling relationship between the circuits and the relationship between the signal waveforms. The circuits, signal waveforms and frequencies are not drawn to scale.

FIG2A is a circuit diagram showing a multi-phase conversion circuit according to an embodiment of the present invention. As shown in FIG2A , the multi-phase conversion circuit 20 of the present invention is used to perform power conversion between a first voltage V1 of a first node N1 and a second voltage V2 of a second node N2. The multi-phase conversion circuit 20 includes a plurality of sub-conversion circuits 201a, 201b and a control circuit 202. The control circuit 202 is used to generate a plurality of switching signals Su1, Su2, Sl1, Sl2, Scr1 and Scr2 to correspondingly control the plurality of switches QUl, QU2, QL1, QL2, Qcr1 and Qcr2 of the plurality of sub-conversion circuits 201a and 201b, and periodically switch the plurality of sub-conversion circuits 201a and 201b between a plurality of electrical connection states to perform power conversion between the first voltage V1 and the second voltage V2.

As shown in FIG. 2A , each of the multiple sub-conversion circuits 201a and 201b includes a capacitor such as capacitor C1 or C2, an inductor such as inductor L1 or L2, and a plurality of switches, and one end of the inductor L1 or L2 is coupled to the second node N2, and the other end of the inductor L1 or L2 and the capacitor C1 or C2 are coupled to the inductance switching node LX1 or LX2 inside each of the multiple sub-conversion circuits 201a and 201b. The multiple switching signals Su1, Su2, Sl1, Sl2, Scr1 and Scr2 operate one of the multiple sub-conversion circuits, such as the capacitor C1 of the sub-conversion circuit 201a, and another of the multiple sub-conversion circuits, such as the capacitor C2 of the sub-conversion circuit 201b, to perform capacitive switching on the first voltage V1 between multiple electrical connection states, so as to switch the inductance switching node, such as the inductance switching node LX1 or LX2 inside one of the multiple sub-conversion circuits between the divided voltage of the first voltage V1 and a reference potential (such as the ground potential), thereby performing power conversion between the first voltage V1 and the second voltage V2. In one embodiment, the minimum number of the above-mentioned voltage division types is 1, and the maximum number of the above-mentioned voltage division types is the number of the plurality of sub-conversion circuits minus 1.

As shown in FIG2A , some of the multiple switches of the sub-conversion circuit 201a include an upper bridge switch QU1, a lower bridge switch QL1, and a jumper switch Qcr1. The upper bridge switch QU1 is coupled between the first node N1 and the capacitor C1, and the lower bridge switch QL1 is coupled between the inductor switching node LX1 and the reference potential. The jumper switch Qcr1 is coupled between the capacitor switching node Nc1 between the upper bridge switch QU1 and the capacitor C1 and the inductor switching node LX2 inside the sub-conversion circuit 201b. Some of the multiple switches of the sub-conversion circuit 201b include an upper bridge switch QU2, a lower bridge switch QL2, and a jumper switch Qcr2. The upper bridge switch QU2 is coupled between the first node N1 and the capacitor C2, and the lower bridge switch QL2 is coupled between the inductor switching node LX2 and the reference potential. The jumper switch Qcr2 is coupled between the capacitor switching node Nc2 between the upper bridge switch QU2 and the capacitor C2 and the inductor switching node LX1 inside the sub-conversion circuit 201a.

As shown in FIG2A , the control circuit 202 generates switching signals Su1, Su2, Sl1, Sl2, Scr1 and Scr2 according to the first voltage V1, the second voltage V2, the inductor current iL1, the inductor current iL2 and the load level to switch the corresponding switches QU1, QU2, QL1, QL2, Qcr1 and Qcr2 to switch the electrical connection state and magnetize the inductor L1 or L2 at a fixed conduction time. The control circuit 202 includes zero current detection circuits 2021a, 2021b, a phase control logic circuit 2022 and conduction time control circuits 2023a-2023f. The zero current detection circuit 2021a is coupled between the phase control logic circuit 2022 and the second voltage V2 to detect the inductor current iL1. The zero current detection circuit 2021b is coupled between the phase control logic circuit 2022 and the second voltage V2 to detect the inductor current iL2. When the zero current detection circuit 2021a detects that the inductor current iL1 is zero, a zero current detection signal ZCD1 is generated to the phase control logic circuit 2022. When the zero current detection circuit 2021b detects that the inductor current iL2 is zero, a zero current detection signal ZCD2 is generated to the phase control logic circuit 2022. The zero current detection circuit 2021a or 2021b may include a current flow detection circuit 20211a or 20211b, respectively, for sensing the inductor current iL1 or the inductor current iL2. The zero current detection circuit 2021a or 2021b may further include a comparator 20212a or 20212b, respectively, for comparing the sensed inductor current iL1 or the inductor current iL2 with a reference signal Vref1 or Vref2, respectively, to generate a zero current detection signal ZCD1 or ZCD2.

The phase control logic circuit 2022 is used to generate phase control signals Spc1~Spc6 according to the first voltage V1, the second voltage V2, the zero current detection signal ZCD1 and/or ZCD2. The on-time control circuits 2023a~2023f are used to generate switching signals Su1, Su2, Sl1, Sl2, Scr1 and Scr2 according to the phase control signals Spc1~Spc6 and the first voltage V1 and the second voltage V2 respectively.

FIG8 is a signal waveform diagram showing relevant signals of the multi-phase conversion circuit of FIG2A according to an embodiment of the present invention. Please refer to FIG2A and FIG8 simultaneously. When the inductors of each of the multi-phase conversion circuits are non-electromagnetic coupling with each other, that is, the switching frequency of the switching signals Su1, Su2, Sl1, Sl2, Scr1 and Scr2 is much higher than the resonant frequency, the multi-phase conversion circuit 20 operates in a non-resonant mode. As shown in FIG8, at least two inductor currents of at least two inductors of at least two of the multi-phase conversion circuits, such as the inductor currents iL1 and iL2, have a phase difference. As shown in FIG. 2A and FIG. 8 , a plurality of sub-conversion circuits periodically switch two sub-conversion circuits in a continuous sequence between a plurality of electrical connection states in a circular sequence (in the embodiment shown in FIG. 2A , there are only two sub-conversion circuits, and therefore each cycle is the switching of these two sub-conversion circuits), that is, the first electrical connection state S1, the second electrical connection state S2, the third electrical connection state S3 and the second electrical connection state S2 are continuously switched and this switching cycle Tsw is repeated. The inductor switching node LX1 or LX2 is switched between the half voltage 1/2*V1 of the first voltage V1 and the reference potential (ground potential in this embodiment), thereby performing power conversion between the first voltage V1 and the second voltage V2.

FIG. 2B is a circuit diagram showing a control circuit of a multi-phase conversion circuit according to another embodiment of the present invention. The control circuit 202' of this embodiment is similar to the control circuit 202 of FIG. 2A, except that the control circuit 202' of this embodiment omits the on-time control circuit 2023a~2023f and the phase control signals Spc1~Spc6. In other words, the phase control logic circuit 2022 directly generates the switching signals Su1, Su2, Sl1, Sl2, Scr1 and Scr2 according to the zero current detection signal ZCD1 or ZCD2.

FIG. 2C to FIG. 2F are circuit diagrams and operation diagrams of a multi-phase conversion circuit according to an embodiment of the present invention. FIG. 2C to FIG. 2F are intended to illustrate the electrical connection relationship between the capacitors C1 and C2, the inductors L1 and L2 in the multi-phase conversion circuit 20 and the first voltage V1, the second voltage V2 and the reference potential (here, the ground potential) in the first electrical connection state S1, the second electrical connection state S2, the third electrical connection state S3 and the fourth electrical connection state S4, respectively. In other embodiments, a combination of multiple electrical connection states in the first electrical connection state S1, the second electrical connection state S2, the third electrical connection state S3 and the fourth electrical connection state S4 may be selected, and these electrical connection states may be periodically repeated to achieve power conversion between the first voltage V1 and the second voltage V2.

As shown in FIG. 2C and FIG. 8 , in the first electrical connection state S1, the upper bridge switch QU2, the jumper switch Qcr1 and the lower bridge switch QL1 are switched to non-conducting, and the upper bridge switch QU1, the jumper switch Qcr2 and the lower bridge switch QL2 are switched to conducting, so that the capacitors C1 and C2 are connected in series between the first voltage V1 and the reference potential (e.g., the ground potential), the capacitors C1 and C2 are coupled to the capacitor switching node Nc2, the inductor L1 is coupled between the capacitor switching node Nc2 and the second voltage V2, and the inductor L2 is coupled between the reference potential and the second voltage V2.

As shown in FIG. 2D and FIG. 8 , in the second electrical connection state S2, the upper bridge switches QU1 and QU2, the cross-connection switches Qcr1 and Qcr2 are switched to non-conductive, and the lower bridge switches QL1 and QL2 are switched to conductive, so that the inductors L1 and L2 are connected in parallel between the reference potential and the second voltage V2.

As shown in FIG. 2E and FIG. 8 , in the third electrical connection state S3, the upper bridge switch QU1, the jumper switch Qcr2 and the lower bridge switch QL2 are switched to non-conducting, and the upper bridge switch QU2, the jumper switch Qcr1 and the lower bridge switch QL1 are switched to conducting, so that the capacitors C2 and C1 are connected in series between the first voltage V1 and the reference potential (e.g., the ground potential), the capacitor C2 and the capacitor C1 are coupled to the capacitor switching node Nc1, the inductor L2 is coupled between the capacitor switching node Nc1 and the second voltage V2, and the inductor L1 is coupled between the reference potential and the second voltage V2.

As shown in FIG. 2F and FIG. 8 , in the fourth electrical connection state S4, the jumper switches Qcr1 and Qcr2, the lower bridge switches QL1 and QL2 are switched to non-conductive, and the upper bridge switches QU1 and QU2 are switched to conductive, so that the capacitors C1 and C2 are respectively connected in series with the inductors L1 and L2 and then connected in parallel between the first voltage V1 and the second voltage V2.

FIG3 is a circuit diagram showing a multi-phase conversion circuit according to another embodiment of the present invention. As shown in FIG3, this embodiment is similar to the embodiment of FIG2A, except that the inductors L1 and L2 of this embodiment are electromagnetically coupled to each other. It should be noted that the inductors in other embodiments of multi-phase conversion circuits having different numbers of sub-conversion circuits can also be electromagnetically coupled to each other in pairs. FIG10 is a signal waveform diagram showing relevant signals of the multi-phase conversion circuit of FIG3 according to one embodiment of the present invention. FIG11 is a signal waveform diagram showing relevant signals of the multi-phase conversion circuit of FIG3 according to another embodiment of the present invention. Please refer to FIG. 3 and FIG. 10 at the same time. When at least two inductors in the multiple sub-conversion circuit are electromagnetically coupled to each other, the multi-phase conversion circuit 20 operates in a resonant mode. In another embodiment, please refer to FIG. 3 and FIG. 11 at the same time. When at least two inductors in the multiple sub-conversion circuit are electromagnetically coupled to each other, the multi-phase conversion circuit 20 operates in a non-resonant mode. In one embodiment, the control circuit 202 can adopt the control circuit architecture of FIG. 2A or 2B.

FIG. 4 is a circuit diagram showing a multi-phase conversion circuit according to another embodiment of the present invention. This embodiment is similar to the embodiment of FIG. 2A , except that this embodiment shows an embodiment of three sub-conversion circuits 201a, 201b, and 201c. It should be noted that the number of sub-conversion circuits described above is an exemplary embodiment, and the present invention is not limited to the number of sub-conversion circuits shown in the embodiment. The present invention can be implemented in any number of sub-conversion circuits greater than 1. In one embodiment, the plurality of sub-conversion circuits 201a, 201b and 201c periodically switch two sub-conversion circuits in a continuous sequence in a circular sequence, such as sub-conversion circuits 201a and 201b or sub-conversion circuits 201b and 201c or sub-conversion circuits 201c and 201a, between a plurality of electrical connection states to switch the inductor switching node LX1 or LX2, LX2 or LX3, LX3 or LX1 between the first voltage V1, which is a half-divided voltage 1/2*V1, and the reference potential, thereby performing power conversion between the first voltage V1 and the second voltage V2. In one embodiment, the control circuit 202 may adopt the control circuit architecture of FIG. 2A or 2B.

Fig. 5 is a circuit diagram showing a multi-phase conversion circuit according to another embodiment of the present invention. This embodiment is similar to the embodiment of Fig. 4, but the difference is that this embodiment periodically switches three sub-conversion circuits in a continuous sequence. In one embodiment, the number of the plurality of sub-conversion circuits is 3, and all sub-conversion circuits 201a, 201b and 201c in a continuous sequence are periodically switched between a plurality of electrical connection states in a ring sequence, so that all inductance switching nodes of all sub-conversion circuits, such as inductance switching nodes LX1, LX2 and LX3, are correspondingly switched between one-third of the first voltage V1 divided by 1/3*V1, two-thirds of the first voltage V1 divided by 2/3*V1 and the reference potential, thereby performing power conversion between the first voltage V1 and the second voltage V2. In one embodiment, the control circuit 202 can adopt the control circuit architecture of Figure 2A or 2B.

FIG6 is a circuit diagram showing a multi-phase conversion circuit according to another embodiment of the present invention. This embodiment is similar to the embodiment of FIG4, except that this embodiment shows an embodiment of four sub-conversion circuits 201a, 201b, 201c and 201d. In one embodiment, the plurality of sub-conversion circuits 201a, 201b, 201c and 201d periodically switch between two sub-conversion circuits in a continuous sequence in a circular sequence, such as sub-conversion circuits 201a and 201b and sub-conversion circuits 201c and 201d, or sub-conversion circuits 201b and 201c and sub-conversion circuits 201d and 201d. 1a, between a plurality of electrical connection states, the inductor switching nodes LX1a and LX2a and LX1b and LX2b, or LX2a and LX1b and LX2b and LX1a are switched between a half voltage divided by 1/2*V1 of the first voltage V1 and a reference potential, thereby performing power conversion between the first voltage V1 and the second voltage V2. It should be noted that in another embodiment, four sub-converter circuits in a continuous sequence may be periodically switched, that is, the number of the plurality of sub-converter circuits is 4, and all the sub-converter circuits 201a, 201b, 201c and 201d in a continuous sequence are periodically switched between the plurality of electrical connection states in a circular sequence to switch all the sub-converter circuits. The inductor switching nodes such as the inductor switching nodes LX1a, LX2a, LX1b and LX2b are correspondingly switched between the first voltage V1, which is one-quarter voltage 1/4*V1, two-quarter voltage 2/4*V1, three-quarter voltage 3/4*V1 and the reference potential, thereby performing power conversion between the first voltage V1 and the second voltage V2. In one embodiment, the control circuit 202 can adopt the control circuit architecture of Figure 2A or 2B.

FIG7 is a circuit diagram showing a multi-phase conversion circuit according to another embodiment of the present invention. This embodiment is different from the embodiment of FIG2A in that it further includes an auxiliary switching capacitor circuit 203. The auxiliary switching capacitor circuit 203 is coupled to one of the sub-conversion circuits 201a and the other sub-conversion circuit 201b. As shown in FIG7, the auxiliary switching capacitor circuit 203 includes an auxiliary capacitor Cau and a plurality of auxiliary switches Qau1 and Qau2. In addition to the switching signals Su1, Su2, Sl1, Sl2, Scr1 and Scr2, the control circuit 202 also generates a plurality of auxiliary switching signals Sau1 and Sau2 to control the plurality of auxiliary switches Qau1 and Qau2 of the auxiliary switching capacitor circuit 203 and the plurality of switches QU1 and QU2 of one sub-converter circuit 201a and the other sub-converter circuit 201b. , QL1, QL2, Qcr1, Qcr2, and periodically switch the auxiliary capacitor Cau and one of the sub-conversion circuits 201a and the other sub-conversion circuit 201b between the first auxiliary electrical connection state and the second auxiliary electrical connection state to perform a switching capacitor voltage conversion of the first voltage V1, and adjust the capacitive bias of the auxiliary capacitor Cau to the auxiliary voltage division of the first voltage V1. In one embodiment, the control circuit 202 can adopt the control circuit architecture of Figure 2A or 2B.

In the first auxiliary electrical connection state, the auxiliary switch Qau2, the upper bridge switch QU2, the jumper switch Qcr1, and the lower bridge switch QL1 are switched to conduction, and the auxiliary switch Qau1, the upper bridge switch QU1, the jumper switch Qcr2, and the lower bridge switch QL2 are switched to non-conduction, so that the capacitor C1 of the sub-conversion circuit 201a and the capacitor C2 of another sub-conversion circuit 201b are connected in series and then connected in parallel with the auxiliary capacitor Cau between the auxiliary switching node Nau and the reference potential inside the auxiliary switching capacitive circuit 203.

In the second auxiliary electrical connection state, the auxiliary switch Qau1, the upper bridge switch QU1, the jumper switch Qcr2, and the lower bridge switch QL2 are switched to conduction, and the auxiliary switch Qau2, the upper bridge switch QU2, the jumper switch Qcr1, and the lower bridge switch QL1 are switched to non-conduction, so that the capacitor C1 of the sub-conversion circuit 201a and the capacitor C2 of the sub-conversion circuit 201b are connected in series with the auxiliary capacitor Cau between the first node N1 and the reference potential.

FIG8 is a signal waveform diagram showing the relevant signals of the multi-phase conversion circuit of FIG2A according to an embodiment of the present invention. The switching signals Su1, Scr1, Sl1, Su2, Scr2, Sl2, inductor currents iL1 and iL2, output inductor current iLout, and switching period Tsw are shown in FIG8. As shown in FIG8, the sequence of the plurality of electrical connection states of the present embodiment is the first electrical connection state S1 (time point t0 to time point t1), the second electrical connection state S2 (time point t1 to time point t2), the third electrical connection state S3 (time point t2 to time point t3) and the second electrical connection state S2 (time point t3 to time point t4).

FIG9 is a signal waveform diagram showing related signals of the multi-phase conversion circuit of FIG2A according to another embodiment of the present invention. Switching signals Su1, Scr1, Sl1, Su2, Scr2, Sl2, inductor currents iL1 and iL2, output inductor current iLout, and switching period Tsw are shown in FIG9. As shown in FIG9, the sequence of the plurality of electrical connection states of the present embodiment is the fourth electrical connection state S4 (time point t0 to time point t1), the first electrical connection state S1 (time point t1 to time point t2), the fourth electrical connection state S4 (time point t2 to time point t3), and the third electrical connection state S3 (time point t3 to time point t4).

FIG10 is a signal waveform diagram showing relevant signals of the multi-phase conversion circuit of FIG3 according to an embodiment of the present invention. Switching signals Su1, Scr1, Sl1, Su2, Scr2, Sl2, inductor currents iL1 and iL2, output inductor current iLout, zero current detection signal ZCD1 or ZCD2, and switching period Tsw are shown in FIG10. As shown in FIG10, the sequence of the plurality of electrical connection states of the present embodiment is the first electrical connection state S1 (time point t0 to time point t1) and the third electrical connection state S3 (time point t2 to time point t3). Please refer to FIG. 10 and FIG. 3 at the same time. When the multi-phase conversion circuit 20 operates in the resonance mode, when the control circuit 202 detects that the inductor currents iL1 and iL2 flowing through the inductors L1 and L2 are zero currents, zero current detection signals ZCD1 and ZCD2 are generated to switch the corresponding switches QU1, QU2, QL1, QL2, Qcr1, and Qcr2.

FIG11 is a signal waveform diagram showing the relevant signals of the multi-phase conversion circuit of FIG3 according to another embodiment of the present invention. The switching signals Su1, Scr1, Sl1, Su2, Scr2, Sl2, inductor currents iL1 and iL2, output inductor current iLout, and switching period Tsw are shown in FIG11. As shown in FIG11, the sequence of the plurality of electrical connection states of the present embodiment is the first electrical connection state S1 (time point t0 to time point t1), the second electrical connection state S2 (time point t1 to time point t2), the third electrical connection state S3 (time point t2 to time point t3) and the second electrical connection state S2 (time point t3 to time point t4).

FIG. 12 to FIG. 15 are signal waveform diagrams showing relevant signals of the multi-phase conversion circuit of FIG. 2A according to the embodiment of the present invention. Please refer to FIG. 12 and FIG. 2A at the same time. The control circuit 202 generates switching signals Su1, Su2, Sl1, Sl2, Scr1, Scr2 according to the load level to switch the corresponding upper bridge switches QU1, QU2, lower bridge switches QL1, QL2, and cross-connection switches Qcr1, Qcr2 to switch the electrical connection state and make the multiple sub-conversion circuits 201a and 201b operate in the boundary conduction mode (BCM). As shown in FIG. 12, the corresponding switch is switched at the zero current point when the inductor current iL1 or iL2 is zero, thereby achieving the soft switching of zero current switching (ZCS).

Please refer to Figure 13 and Figure 2A at the same time. The control circuit 202 generates switching signals Su1, Su2, Sl1, Sl2, Scr1, and Scr2 according to the load level to switch the corresponding upper bridge switches QU1, QU2, lower bridge switches QL1, QL2, and jumper switches Qcr1 and Qcr2 to switch the electrical connection state and make the multiple sub-conversion circuits 201a and 201b operate in a discontinuous conduction mode (DCM). Please refer to FIG. 14 and FIG. 2A at the same time. The control circuit 202 generates switching signals Su1, Su2, Sl1, Sl2, Scr1, Scr2 according to the load level to switch the corresponding upper bridge switches QU1, QU2, lower bridge switches QL1, QL2, and jumper switches Qcr1, Qcr2 to switch the electrical connection state and make the multiple sub-converter circuits 201a and 201b operate in continuous conduction mode (continuous conduction mode, CCM).

FIG16 is a circuit diagram and an operation diagram of a multi-phase conversion circuit according to an embodiment of the present invention. Please refer to FIG15 and FIG16 simultaneously, after the inductor L1 or L2 is demagnetized, and the inductor current iL1 or iL2 flowing through the inductor L1 or L2 is zero, the switching signals Su2, Scr1, Sl1 wait for a delay time td, and switch the corresponding upper bridge switch QU2, the jumper switch Qcr1, and the lower bridge switch QL1 to switch from the second electrical connection state to the third electrical connection state. As shown in FIG16 , after switching to the third electrical connection state, the reverse inductor current iL2 on the inductor L2 will flow along the path of the thick dashed line to the first voltage V1 or the second voltage V2, thereby utilizing the energy on the jumper switch Qcr1 and the upper bridge switch QU2 and activating the body diode on the jumper switch Qcr1 and the upper bridge switch QU2, thereby achieving a soft switching of zero voltage switching (ZVS).

As described above, the multi-phase conversion circuit of the present invention can achieve higher power conversion efficiency, smaller inductor size and lower voltage stress on components.

The present invention has been described above with reference to the preferred embodiments. However, the above description is only for the purpose of making it easier for those familiar with the art to understand the content of the present invention, and is not intended to limit the broadest scope of the present invention. The embodiments described are not limited to single application, but can also be applied in combination. For example, two or more embodiments can be used in combination, and a part of the components in one embodiment can also be used to replace the corresponding components in another embodiment. In addition, under the same spirit of the present invention, those familiar with the present technology can think of various equivalent changes and various combinations. For example, the present invention refers to "processing or calculating or generating an output result according to a certain signal", which is not limited to the signal itself, but also includes, when necessary, converting the signal into voltage-current, current-voltage, and/or ratio, and then processing or calculating the converted signal to generate an output result. It can be seen that under the same spirit of the present invention, those familiar with the present technology can think of various equivalent changes and various combinations, and there are many combinations, which are not listed here one by one. Therefore, the scope of the present invention should cover the above and all other equivalent changes.

20: Multi-phase conversion circuit

201a,201b,201c,201d: Sub-conversion circuit

202,202’: Control circuit

2021a,2021b: Zero current detection circuit

20211a,20211b: Current flow measurement circuit

20212a,20212b: Comparator

2022: Phase control logic circuit

2023a~2023f: On-time control circuit

203: Auxiliary switching capacitor circuit

C1, C1a, C1b, C2, C2a, C2b, C3: capacitors

Cau: Auxiliary capacitor

iL1,iL2,iL3,iL1a,iL1b,iL2a,iL2b: inductor current

iLout: output inductor current

L1, L1a, L1b, L2, L2a, L2b, L3: Inductor

LX1, LX2, LX3, LX1a, LX1b, LX2a, LX2b: Inductor switching nodes

N1: First node

N2: Second node

Nc1, Nc2, Nc3, Nc4: Capacitor switching nodes

Nau: Assisted switching node

Qau1, Qau2: Auxiliary switch

Qcr1, Qcr2, Qcr3, Qcr1a, Qcr1b, Qcr2a, Qcr2b: (jumper) switch

QL1,QL2,QL3,QL1a,QL1b,QL2a,QL2b: (down bridge) switch

QU1, QU2, QU3, QU1a, QU1b, QU2a, QU2b: (bridge) switch

S1: First electrical connection state

S2: Second electrical connection state

S3: The third electrical connection state

S4: Fourth electrical connection state

Sau1, Sau2: auxiliary switching signal

Scr1, Scr2, Scr3, Scr1a, Scr1b, Scr2a, Scr2b, Sl1, Sl2, Sl3, Sl1a, Sl1b, Sl2a, Sl2b, Su1, Su2, Su3, Su1a, Su1b, Su2a, Su2b: Switching signal

Spc1~Spc6: Phase control signal

t0,t1,t2,t3,t4: time points

td: delay time

Tsw: switching cycle

V1: first voltage

V2: Second voltage

Vref1, Vref2: reference signal

ZCD1, ZCD2: zero current detection signal

FIG1 is a circuit diagram showing a known two-phase conversion circuit.

FIG2A is a circuit diagram showing a multi-phase conversion circuit according to an embodiment of the present invention.

FIG2B is a circuit diagram showing a control circuit of a multi-phase conversion circuit according to another embodiment of the present invention.

Figures 2C to 2F show the circuit schematic diagram and operation schematic diagram of the multi-phase conversion circuit according to the embodiment of the present invention.

FIG3 is a circuit diagram showing a multi-phase conversion circuit according to another embodiment of the present invention.

FIG4 is a circuit diagram showing a multi-phase conversion circuit according to another embodiment of the present invention.

FIG5 is a circuit diagram showing a multi-phase conversion circuit according to another embodiment of the present invention.

FIG6 is a circuit diagram showing a multi-phase conversion circuit according to another embodiment of the present invention.

FIG7 is a circuit diagram showing a multi-phase conversion circuit according to another embodiment of the present invention.

FIG8 is a schematic diagram showing the signal waveforms of the relevant signals of the multi-phase conversion circuit of FIG2A according to one embodiment of the present invention.

FIG. 9 is a schematic diagram showing the signal waveforms of the relevant signals of the multi-phase conversion circuit of FIG. 2A according to another embodiment of the present invention.

FIG. 10 is a schematic diagram showing the signal waveforms of the relevant signals of the multi-phase conversion circuit of FIG. 3 according to an embodiment of the present invention.

FIG. 11 is a schematic diagram showing the signal waveforms of the relevant signals of the multi-phase conversion circuit of FIG. 3 according to another embodiment of the present invention.

Figures 12 to 15 are schematic diagrams showing signal waveforms of related signals of the multi-phase conversion circuit of Figure 2A according to an embodiment of the present invention.

FIG. 16 is a circuit diagram and an operation diagram showing a multi-phase conversion circuit according to an embodiment of the present invention.

20: Multi-phase conversion circuit

201a,201b: Sub-conversion circuit

202: Control circuit

2021a,2021b: Zero current detection circuit

20211a,20211b: Current flow measurement circuit

20212a,20212b: Comparator

2022: Phase control logic circuit

2023a~2023f: On-time control circuit

C1,C2:Capacitors

iL1,iL2: inductor current

iLout: output inductor current

L1, L2: Inductor

LX1, LX2: Inductor switching nodes

N1: First node

N2: Second node

Nc1, Nc2: Capacitor switching nodes

Qcr1, Qcr2: (jumper) switch

QL1, QL2: (down bridge) switch

QU1, QU2: (bridge) switch

Scr1, Scr2, Sl1, Sl2, Su1, Su2: switching signal

Spc1~Spc6: Phase control signal

V1: first voltage

V2: Second voltage

Vref1, Vref2: reference signal

ZCD1, ZCD2: zero current detection signal

Claims (25)

A multi-phase conversion circuit is used to perform power conversion between a first voltage of a first node and a second voltage of a second node. The multi-phase conversion circuit includes: a plurality of sub-conversion circuits; and a control circuit, which is used to generate a plurality of switching signals to control a plurality of switches of the plurality of sub-conversion circuits in response, and periodically switch the plurality of sub-conversion circuits between a plurality of electrical connection states to perform power conversion between the first voltage and the second voltage; wherein each of the plurality of sub-conversion circuits includes a capacitor, an inductor and part of the plurality of switches, and one end of the inductor is coupled to the second node, and the other end of the inductor and the capacitor are coupled to the plurality of sub-conversion circuits. an inductor switching node inside each of the plurality of sub-conversion circuits; wherein the plurality of switching signals, between the plurality of electrical connection states, operate the capacitor of one of the plurality of sub-conversion circuits and the capacitor of another of the plurality of sub-conversion circuits to perform capacitive switching on the first voltage, so as to switch the inductor switching node inside one of the plurality of sub-conversion circuits between a divided voltage of the first voltage and a reference potential, thereby performing power conversion between the first voltage and the second voltage; wherein when the inductors of each of the plurality of sub-conversion circuits are non-electromagnetic coupling (non-electromagnetic coupling) with each other, coupling), the multi-phase conversion circuit operates in a non-resonant mode; wherein when the inductors of at least two of the plurality of sub-conversion circuits are electromagnetically coupled to each other, the multi-phase conversion circuit operates in a resonant mode or the non-resonant mode; wherein the number of the plurality of sub-conversion circuits is N, and all the sub-conversion circuits in a continuous sequence are periodically switched between the plurality of electrical connection states in a ring sequence, so as to switch all the inductance switching nodes of all the sub-conversion circuits to one-Nth voltage division of the first voltage, ..., and so on to between N-1th voltage division of Nth and the reference potential, thereby performing power conversion between the first voltage and the second voltage, wherein N is a positive integer greater than or equal to 2. A multi-phase conversion circuit as described in claim 1, wherein at least two inductor currents of at least two of the at least two inductors in the multi-phase conversion circuit have a phase difference. A multi-phase conversion circuit as described in claim 1, wherein the number of voltage dividers is at least 1 and at most the number of the plurality of sub-conversion circuits minus 1. A multi-phase conversion circuit as described in claim 1, wherein the plurality of switches of one of the plurality of sub-conversion circuits include: a bridge switch coupled between the first node and the capacitor; a bridge switch coupled between the inductor switching node of the one of the plurality of sub-conversion circuits and the reference potential; and a jumper switch coupled between a capacitor switching node between the bridge switch and the capacitor of the one of the plurality of sub-conversion circuits and the inductor switching node of another of the plurality of sub-conversion circuits. The multi-phase conversion circuit as described in claim 1 further includes an auxiliary switching capacitor circuit, the auxiliary switching capacitor circuit is coupled to the one sub-conversion circuit and the other sub-conversion circuit, the auxiliary switching capacitor circuit includes an auxiliary capacitor and a plurality of auxiliary switches; wherein the control circuit further generates a plurality of auxiliary switching signals to correspond to the plurality of auxiliary switches of the auxiliary switching capacitor circuit and the plurality of switches of the one sub-conversion circuit and the other sub-conversion circuit, and periodically switches the auxiliary capacitor and the one sub-conversion circuit and the other sub-conversion circuit between a first auxiliary electrical connection state and a second auxiliary electrical connection state. states to perform the switching capacitor voltage conversion of the first voltage, and adjust the capacitance bias of the auxiliary capacitor to an auxiliary voltage division of the first voltage; wherein the first auxiliary electrical connection state includes the capacitor of one of the sub-conversion circuits and the capacitor of the other sub-conversion circuit being connected in series with the auxiliary capacitor and then connected in parallel between an auxiliary switching node inside the auxiliary switching capacitor circuit and the reference potential; wherein the second auxiliary electrical connection state includes the capacitor of one of the sub-conversion circuits and the capacitor of the other sub-conversion circuit being connected in series with the auxiliary capacitor and then connected in series between the first node and the reference potential. A multi-phase conversion circuit as described in claim 1, wherein the switching signal switches the corresponding switch after a zero current time point indicating that an inductor current flowing through the inductor is zero current according to a zero current signal, so as to switch the electrical connection state. A multi-phase conversion circuit as described in claim 6, wherein the switching signal waits for a dead-time after the zero current point, and then switches the corresponding switch to switch the electrical connection state. A multi-phase conversion circuit as described in claim 6, wherein the plurality of switches achieves soft switching of zero current switching (ZCS) and/or zero voltage switching (ZVS). A multi-phase conversion circuit as described in claim 1, wherein the control circuit generates the switching signal to switch the corresponding switch according to the first voltage, the second voltage and a load level to switch the electrical connection state and magnetize the inductor at a fixed conduction time. A multi-phase conversion circuit as described in claim 1, wherein the control circuit generates the switching signal to switch the corresponding switch according to a load level to switch the electrical connection state, and enables the multi-phase conversion circuit to operate in a boundary conduction mode (BCM), a continuous conduction mode (CCM) or a discontinuous conduction mode (DCM). A multi-phase conversion circuit as described in claim 1, wherein the switching signal waits for a delay time after the inductor is demagnetized and an inductor current flowing through the inductor becomes zero current, and switches the corresponding switch to switch the electrical connection state. A multi-phase conversion circuit as described in claim 1, wherein the control circuit includes a zero current detection circuit, and when an inductor current flowing through the inductor is zero current, the zero current detection circuit generates a zero current detection signal to switch the corresponding switch. A multi-phase conversion circuit as described in claim 1, wherein when the multi-phase conversion circuit operates in the resonance mode, when the control circuit detects that an inductor current flowing through the inductor is zero current, a zero current detection signal is generated to switch the corresponding switch. A multi-phase conversion circuit control method, the multi-phase conversion circuit control method comprising: generating a plurality of switching signals to correspond to a plurality of switches of a plurality of sub-conversion circuits of a multi-phase conversion circuit, and periodically switching the plurality of sub-conversion circuits between a plurality of electrical connection states to perform power conversion between a first voltage of a first node and a second voltage of a second node, wherein each of the plurality of sub-conversion circuits includes a capacitor, an inductor and part of the plurality of switches, and one end of the inductor is coupled to the second node, and the other end of the inductor and the capacitor are coupled to an inductive switching node inside each of the plurality of sub-conversion circuits; the plurality of switching signals operate the capacitor of one of the plurality of sub-conversion circuits and the capacitor of another sub-conversion circuit in the plurality of sub-conversion circuits to switch the first capacitor between the plurality of electrical connection states; The plurality of switching signals are used to perform capacitive switching to switch the inductor switching node in one of the plurality of sub-conversion circuits between a divided voltage of the first voltage and a reference potential, thereby performing power conversion between the first voltage and the second voltage; and the plurality of switching signals are used to periodically switch all the sub-conversion circuits in a continuous sequence in the plurality of sub-conversion circuits according to a ring sequence between the plurality of electrical connection states, so as to switch all the sub-conversion circuits to the first voltage. All the inductor switching nodes of the conversion circuit are correspondingly switched between the 1/N voltage division of the first voltage, ..., and so on to the N-1 voltage division of N and the reference potential, thereby performing power conversion between the first voltage and the second voltage, wherein N is a positive integer greater than or equal to 2; wherein when the inductors of each of the multiple sub-conversion circuits are non-electromagnetic coupling with each other, the multi-phase conversion circuit operates in a non-resonant mode; wherein when the inductors of at least two of the multiple sub-conversion circuits are electromagnetically coupled with each other, the multi-phase conversion circuit operates in a resonant mode or the non-resonant mode. A multi-phase conversion circuit control method as described in claim 14, wherein at least two inductor currents of at least two of the at least two inductors in the multi-phase conversion circuit have a phase difference. A multi-phase conversion circuit control method as described in claim 14, wherein the minimum number of voltage divisions is 1 and the maximum number of the plurality of sub-conversion circuits minus 1. The multi-phase conversion circuit control method as described in claim 14 further includes: generating a plurality of auxiliary switching signals to correspond to controlling a plurality of auxiliary switches of an auxiliary switching capacitive circuit and the plurality of switches of one of the sub-conversion circuits and the other sub-conversion circuit, and periodically switching an auxiliary capacitor of the auxiliary switching capacitive circuit and the one of the sub-conversion circuits and the other sub-conversion circuit between a first auxiliary electrical connection state and a second auxiliary electrical connection state to perform switching capacitive voltage conversion of the first voltage, and adjusting the capacitance bias of the auxiliary capacitor to one of the first voltage. Auxiliary voltage division, wherein the auxiliary switching capacitive circuit is coupled to one of the sub-conversion circuits and the other sub-conversion circuit; wherein the first auxiliary electrical connection state includes the capacitor of one of the sub-conversion circuits and the capacitor of the other sub-conversion circuit being connected in series and then connected in parallel with the auxiliary capacitor between an auxiliary switching node inside the auxiliary switching capacitive circuit and the reference potential; wherein the second auxiliary electrical connection state includes the capacitor of one of the sub-conversion circuits and the capacitor of the other sub-conversion circuit being connected in series and then connected in series with the auxiliary capacitor between the first node and the reference potential. The multi-phase conversion circuit control method as described in claim 14 further includes: the switching signal switches the corresponding switch to switch the electrical connection state after a zero current time point indicating that an inductor current flowing through the inductor is zero current according to a zero current signal. The multi-phase conversion circuit control method as described in claim 18 further includes: the switching signal waits for a dead-time after the zero current point, and then switches the corresponding switch to switch the electrical connection state. A multi-phase conversion circuit control method as described in claim 18, wherein the plurality of switches achieves soft switching of zero current switching (ZCS) and/or zero voltage switching (ZVS). A multi-phase conversion circuit control method as described in claim 14, wherein the switching signal is generated according to the first voltage, the second voltage and a load level to switch the corresponding switch to switch the electrical connection state and magnetize the inductor at a fixed conduction time. A multi-phase conversion circuit control method as described in claim 14, wherein the switching signal is generated according to a load level to switch the corresponding switch to switch the electrical connection state, and to enable the multi-phase conversion circuit to operate in a boundary conduction mode (BCM), a continuous conduction mode (CCM) or a discontinuous conduction mode (DCM). The multi-phase conversion circuit control method as described in claim 14 further includes: after the inductor is demagnetized and an inductor current flowing through the inductor becomes zero current, a delay time is waited, and the corresponding switch is switched to switch the electrical connection state. The multi-phase conversion circuit control method as described in claim 14 further includes: when an inductor current flowing through the inductor is zero current, a zero current detection signal is generated to switch the corresponding switch. The multi-phase conversion circuit control method as described in claim 14 further includes: when the multi-phase conversion circuit operates in the resonance mode, when it is detected that an inductor current flowing through the inductor is zero current, a zero current detection signal is generated to switch the corresponding switch.

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