Multi-phase converter circuit

Abstract

This invention discloses a multiphase conversion circuit, including at least one two-phase conversion circuit coupled between a first voltage and a second voltage, which controls at least one capacitor and at least one coupling inductor to alternately switch between charging and discharging phases to achieve power conversion between the first voltage and the second voltage.

Description

[Technical Field]

[0001] The present invention relates to a multiphase conversion circuit, and more particularly to a multiphase conversion circuit with better electromagnetic interference removal performance. [Previous Technology]

[0002] High efficiency and high power density are essential in many applications, such as data centers, servers, electric vehicles, and mobile devices. Recently, many systems have adopted 48V bus voltages to increase maximum power, such as 48V bus voltages in data centers, vehicles, and USB PD EPR systems. Therefore, high voltage conversion ratio, high efficiency, and miniaturization have become key requirements.

[0003] Figure 1 shows a conventional two-phase buck converter circuit. This prior art uses two buck converter circuits connected in parallel to increase the output current. However, in the high-voltage applications described above, this prior art requires high-voltage switching elements to withstand the maximum input voltage. In addition, due to the high voltage across the inductor, the required inductance value must also be large.

[0004] This invention provides a multiphase converter circuit that operates in resonant mode or regulated mode. Compared with conventional multiphase buck converter circuits, this invention has several advantages, including higher power efficiency, smaller inductor size, lower component voltage stress, and higher power density. [Summary of the Invention]

[0005] In one viewpoint, the present invention provides a multiphase conversion circuit comprising at least one two-phase conversion circuit for power conversion between a first voltage and a second voltage, wherein each of the at least one two-phase conversion circuit comprises: a first conversion terminal and a second conversion terminal; a plurality of switches; a first conversion capacitor; and a coupling inductor comprising a first inductor and a second inductor, the first inductor and the second inductor being reverse-coupled, and the coupling inductor having an equivalent leakage inductance; wherein the plurality of switches control the electrical connection relationship between the first conversion capacitor, the first inductor and the second inductor, and the first voltage and the second voltage, thereby generating a plurality of electrical connection states, such that the first conversion capacitor is in a charging phase having a charging time and a charging phase having a charging time. The discharge phases with discharge time are alternately switched; wherein in the charging phase, the multiple switches control the first conversion capacitor and the first inductor to be connected in series between the first conversion terminal and the second conversion terminal, so as to generate a first inductor current in the first inductor and generate a second inductor current through electromagnetic coupling to the second inductor; wherein in the discharge phase, the multiple switches control the first conversion capacitor and the second inductor to be connected in series between the ground potential and the second conversion terminal, so as to generate the second inductor current in the second inductor and generate the first inductor current through electromagnetic coupling to the first inductor; wherein the at least one two-phase conversion circuit includes a first two-phase conversion circuit, wherein the first conversion terminal is coupled to the first voltage and the second conversion terminal is coupled to the second voltage.

[0006] In a preferred embodiment, the charging time and the discharging time are respectively half of the resonant period of the leakage inductance of the first conversion capacitor and the coupling inductor, so as to control the first conversion capacitor and the coupling inductor to resonate and thereby perform power conversion.

[0007] In a preferred embodiment, each of the at least one two-phase conversion circuit includes: a first upper bridge switch coupled between the first conversion terminal and a first shunt node; a first conversion capacitor coupled between the first shunt node and a first switching node; a first lower bridge switch coupled between the first switching node and ground potential; a first inductor coupled between the first switching node and the second conversion terminal; a second upper bridge switch coupled between the first shunt node and a second switching node; and a second lower bridge switch. The first switching capacitor is coupled between the second switching node and the ground potential; and the second inductor is coupled between the second switching node and the second switching terminal; wherein, in the charging phase, the first upper bridge switch is turned on, thereby controlling the first switching capacitor and the first inductor to be connected in series between the first switching terminal and the second switching terminal; wherein, in the discharging phase, the first lower bridge switch and the second upper bridge switch are turned on, thereby controlling the first switching capacitor and the second inductor to be connected in series between the ground potential and the second switching terminal.

[0008] In a preferred embodiment, the at least one two-phase conversion circuit includes a first to a Qth two-phase conversion circuit arranged in sequence, wherein Q is greater than 1, wherein the first conversion terminal of each of the first to Qth two-phase conversion circuits is coupled to the first voltage, and the second conversion terminal is coupled to the second voltage; wherein the corresponding on-state relationships in any two adjacent two-phase conversion circuits are switched in opposite phases.

[0009] In a preferred embodiment, each of the at least one two-phase conversion circuit further includes: an auxiliary switching capacitor conversion circuit, the auxiliary switching capacitor conversion circuit including an auxiliary capacitor, a first auxiliary switch and a second auxiliary switch, wherein the first auxiliary switch is coupled between the first conversion terminal and an auxiliary shunt node, the second auxiliary switch is coupled between the auxiliary shunt node and the first switching node, and the auxiliary capacitor is coupled between the auxiliary shunt node and the second switching node; wherein in the charging phase, the second auxiliary switch is turned on, thereby controlling the auxiliary capacitor to be connected in series with the first inductor. Between the ground potential and the second conversion terminal, the first conversion capacitor and the first inductor are connected in series between the first conversion terminal and the second conversion terminal, and the second inductor is connected in series between the ground potential and the second conversion terminal; wherein in the discharge phase, the first auxiliary switch is turned on, thereby controlling the auxiliary capacitor and the second inductor to be connected in series between the first conversion terminal and the second conversion terminal, and controlling the first conversion capacitor and the second inductor to be connected in series between the ground potential and the second conversion terminal, and controlling the first inductor to be connected in series between the ground potential and the first conversion terminal.

[0010] In a preferred embodiment, the at least one two-phase conversion circuit includes a first to an Mth two-phase conversion circuit arranged in sequence, wherein M is greater than or equal to 2; wherein the first conversion terminal corresponding to the kth two-phase conversion circuit is coupled to a second shunt node of the (k-1)th two-phase conversion circuit, and the second conversion terminal corresponding to the kth two-phase conversion circuit is coupled to the second voltage, wherein k = 2 to M; wherein each of the first to M-1th two-phase conversion circuits further includes a second conversion capacitor, coupled between the second upper bridge switch and the second switching node, and coupled together with the second upper bridge switch to the corresponding second shunt node; wherein the on / off states of the first to Mth two-phase conversion circuits switch in phase with each other.

[0011] In a preferred embodiment, the capacitance value of the second conversion capacitor is much larger than that of the first conversion capacitor, so that the second conversion capacitor does not participate in resonance, and only the first conversion capacitor resonates with the first inductor or the second inductor.

[0012] In a preferred embodiment, the multiphase conversion circuit further includes an auxiliary switching inductor conversion circuit, which includes: an auxiliary upper bridge switch, an auxiliary lower bridge switch, and an auxiliary inductor. The auxiliary upper bridge switch is coupled between the second shunt node and the auxiliary switching node of the Mth two-phase conversion circuit, the auxiliary lower bridge switch is coupled between the auxiliary switching node and the ground potential, and the auxiliary inductor is coupled between the auxiliary switching node and the second voltage. The auxiliary upper bridge switch is further turned on in the charging phase, thereby controlling the auxiliary inductor to be electrically connected between the second shunt node and the second voltage of the Mth two-phase conversion circuit, so as to generate an auxiliary inductor current on the auxiliary inductor.

[0013] In a preferred embodiment, the first two-phase conversion circuit further includes a second conversion capacitor coupled between the second upper bridge switch and the second switching node, and coupled together with the second upper bridge switch to a second shunt node; the multi-phase conversion circuit further includes an auxiliary switching inductor conversion circuit, the auxiliary switching inductor conversion circuit including an auxiliary upper bridge switch, an auxiliary lower bridge switch, and an auxiliary inductor, wherein the auxiliary upper bridge switch is coupled between the second shunt node and the auxiliary switching node of the first two-phase conversion circuit, the auxiliary lower bridge switch is coupled between the auxiliary switching node and the ground potential, and the auxiliary inductor is coupled between the auxiliary switching node and the second voltage; wherein the auxiliary upper bridge switch is further turned on in the charging phase, thereby controlling the auxiliary inductor to be electrically connected between the second shunt node and the second voltage of the first two-phase conversion circuit, so as to generate an auxiliary inductor current on the auxiliary inductor.

[0014] In a preferred embodiment, the first inductor and the second inductor have the same number of turns.

[0015] In a preferred embodiment, the multiple electrical connection states further include an optional freewheeling phase, wherein in the freewheeling phase, the multiple switches control the first inductor and the second inductor to be electrically connected between the ground potential and the second switching terminal, thereby demagnetizing the first inductor and the second inductor.

[0016] In a preferred embodiment, during the charging phase, when the first inductor current flowing through the first inductor drops below a preset zero current threshold, the system switches to the discharging phase; or, during the discharging phase, when the second inductor current flowing through one of the second inductors drops below the preset zero current threshold, the system switches to the charging phase, thereby achieving zero current switching (ZCS) or zero voltage switching (ZVS).

[0017] In a preferred embodiment, at the point when the charging phase transitions to the discharging phase, the first inductor current is higher than the second inductor current, and the difference between the first inductor current and the second inductor current corresponds to an excitation current; at the point when the discharging phase transitions to the charging phase, the second inductor current is higher than the first inductor current, wherein the difference between the second inductor current and the first inductor current corresponds to the excitation current.

[0018] In a preferred embodiment, a lag time is included when the charging phase and the discharging phase switch to each other, wherein during the lag time, the excitation current is used to achieve zero-voltage switching of the first upper bridge switch and / or the second upper bridge switch.

[0019] In a preferred embodiment, in steady state, the DC component of the voltage across the first conversion capacitor of each of the first to Q biphase conversion circuits is 1 / N of the first voltage, and the voltage conversion ratio of the first voltage to the second voltage is 2N:1, where N is a positive integer greater than or equal to 2.

[0020] In a preferred embodiment, in steady state, the DC component of the voltage across the first conversion capacitor of each of the first to k' two-phase conversion circuits is (2M-(2k'-1)) / 2M of the first voltage, and the DC component of the voltage across the second conversion capacitor of each of the two-phase conversion circuits is (2M-2k') / 2M of the first voltage, where k'=1~M, and the voltage conversion ratio between the first voltage and the second voltage is 2M•2:1.

[0021] In a preferred embodiment, in steady state, the DC component of the voltage across the first conversion capacitor of each of the first to k' two-phase conversion circuits is ((2M+1)-(2k'-1)) / (2M+1) of the first voltage, and the DC component of the voltage across the second conversion capacitor of each of the two-phase conversion circuits is ((2M+1)-2k') / (2M+1) of the first voltage, where k'=1~M, and the voltage conversion ratio between the first voltage and the second voltage is (2M+1)•2:1.

[0022] In a preferred embodiment, the ratio between the second voltage and the first voltage is adjusted by controlling the duty cycle and / or switching frequency of the charging phase and / or the discharging phase.

[0023] In a preferred embodiment, the two-phase conversion circuit includes a first current sensing circuit and a second current sensing circuit, which are connected in parallel to the first inductor and the second inductor, respectively, to generate a first current sensing signal and a second current sensing signal to indicate the first inductor current and the second inductor current, respectively. The first current sensing circuit and the second current sensing circuit each include a sensing resistor and a sensing capacitor.

[0024] In a preferred embodiment, during resonant operation, the first switching capacitor is net charged in the charging phase and net discharged in the discharging phase.

[0025] The following detailed description of specific embodiments will make it easier to understand the purpose, technical content, features and effects achieved by the present invention.

Implementation Method

[0042] The diagrams in this invention are all schematic and are mainly intended to show the coupling relationship between circuits and the relationship between signal waveforms. The circuits, signal waveforms and frequencies are not drawn to scale.

[0043] Figure 2 shows one embodiment of the multiphase conversion circuit of the present invention. It is used to convert a first voltage V1 to a second voltage V2, or to convert a second voltage V2 to a first voltage V1. The following description will mainly use the first voltage V1 as the input voltage and the second voltage V2 as the output voltage for most embodiments. In other embodiments, the first voltage V1 may be the output voltage and the second voltage V2 may be the input voltage.

[0044] The conversion circuit 20 includes at least one conversion capacitor (e.g., C1), at least one coupling inductor (e.g., Lc1), and a plurality of switches (e.g., Q1-QN, where N is greater than 2). The coupling inductor Lc1 comprises two mutually coupled first inductors L1 and second inductors L2, which are reverse-coupled and coupled together with an output capacitor Cout to the output voltage V2. The plurality of switches (Q1-QN) control the electrical connection relationship between the first conversion capacitor C1, the first inductors L1 and L2, and the first voltage V1 and the second voltage V2, thereby generating a plurality of electrical connection states, so that the first conversion capacitor alternately switches between a charging phase with a charging time and a discharging phase with a discharging time, thereby performing the conversion between the first voltage V1 and the second voltage V2. In one embodiment, inductors L1 and L2 are coupled to each other to the second voltage V2, thereby further improving the voltage conversion ratio by 2 times.

[0045] Figure 3 shows a specific embodiment of the multiphase conversion circuit of the present invention. The multiphase conversion circuit 200 includes a two-phase conversion circuit 201, whose conversion terminals TN11 and TN12 are respectively coupled to a first voltage V1 and a second voltage V2. The two-phase conversion circuit 201 includes a first conversion capacitor C1, a coupling inductor Lc1 and four switches (Q1-Q4), wherein the four switches (Q1-Q4) correspond to the first upper bridge switch Q1, the first lower bridge switch Q2, the second upper bridge switch Q3 and the second lower bridge switch Q4 of the two-phase conversion circuit 201, respectively. The first upper bridge switch Q1 is coupled between the switching terminal TN11 and the first shunt node NC1. The first switching capacitor C1 is coupled between the first shunt node NC1 and the inductor switching node LX1. The inductor L1 is coupled between the inductor switching node LX1 and the switching terminal TN12. The first lower bridge switch Q2 is coupled between the inductor switching node LX1 and the ground potential. The second upper bridge switch Q3 is coupled between the first shunt node NC1 and the inductor switching node LX2. The inductor L2 is coupled between the inductor switching node LX2 and the switching terminal TN12. The second lower bridge switch Q4 is coupled between the inductor switching node LX2 and the ground potential.

[0046] The control circuit 203 provides switching control signals G1-G4 to control the switching operation of the switches (Q1-Q4) to perform power conversion between the first voltage V1 and the second voltage V2.

[0047] The multiphase conversion circuit can operate in resonant mode to achieve high-efficiency operation, or it can operate in regulation mode to regulate the output voltage. In one embodiment, the multiphase conversion circuit 200 senses inductor currents iL1 and iL2. When the inductor current iL1 or inductor current iL2 is lower than the zero current threshold, the state of the switching switches (Q1-Q4) is switched to achieve resonant mode operation, thereby realizing zero voltage switching (ZVS) and zero current switching (ZCS) to achieve high-efficiency operation. In the resonant mode, the charging time and discharging time are respectively half of the resonant period of the leakage inductance Lk1 or Lk2 of the first conversion capacitor C1 and the coupling inductor Lc1, so as to control the first conversion capacitor C1 and the coupling inductor Lc1 to resonate, thereby performing power conversion between the first voltage V1 and the second voltage V2.

[0048] On the other hand, when operating in the adjustment mode, the multiphase conversion circuit 200 adjusts the duty cycle and switching frequency of the switching control signals G1-G4 (e.g., higher or lower than the resonant frequency of the multiphase conversion circuit 200) to adjust the output voltage to a preset level or limit it to a preset range.

[0049] Furthermore, Figure 3 also shows the circuit model of the coupled inductor Lc1, where Lk1 and Lk2 are the leakage inductances of inductors L1 and L2, respectively, and Lmz is the equivalent magnetizing inductance of the coupled inductor Lc1. In one embodiment, inductors L1 and L2 are reverse-coupled and have the same number of turns (N1:N2 = 1:1), and are considered as ideal transformers, where N1 and N2 are the number of turns of L1 and L2, respectively.

[0050] Referring also to Figures 4 to 6, which show schematic diagrams of several electrical connection states of the multiphase conversion circuit embodiment shown in Figure 3, the first voltage V1 is used as the input voltage and the second voltage is used as the output voltage. In switching state 1 shown in Figure 4, the first upper bridge switch Q1 and the second lower bridge switch Q4 are turned on, the first lower bridge switch Q2 and the second upper bridge switch Q3 are turned off, the conversion capacitor C1 is charged by the input voltage (V1), and the inductor L1 is energized by the difference between the voltage (V1 - Vc1) on the switching node LX1 and the output voltage (V2) through the conversion capacitor C1, so as to generate inductor currents iL1 and iL2 and energizing current iLmz, where Vc1 is the voltage across the first conversion capacitor C1. The output current is equal to the sum of the inductor currents (I2 = iL1 + iL2). In one embodiment, in switching state 1, the second lower bridge switch Q4 may also not be turned on, but is turned on by the body diode of the second lower bridge switch Q4.

[0051] In switching state 2 shown in Figure 5, the first lower bridge switch Q2 and the second upper bridge switch Q3 are turned on, the first upper bridge switch Q1 and the second lower bridge switch Q4 are turned off, the first conversion capacitor C1 is discharged, and the inductor L2 is energized by the voltage Vc1 across the first conversion capacitor C1, generating inductor currents iL1 and iL2 and an excitation current iLmz. In one embodiment, in switching state 2, the first lower bridge switch Q2 may also not be turned on, but is turned on by the body diode of the first lower bridge switch Q2.

[0052] For the first switching capacitor C1, in the aforementioned switching state 1 and switching state 2, the first switching capacitor C1 is net charged and net discharged respectively. Therefore, the aforementioned switching state 1 and switching state 2 can be regarded as the charging phase and the discharging phase respectively.

[0053] Through the above configuration and periodic switching operation, in steady state, the DC component of the voltage Vc1 across the first switching capacitor C1 is V1•1 / 2, and due to the further voltage division of the two branches of the coupling inductor Lc1, the voltage conversion ratio of the input voltage (V1) to the output voltage (V2) reaches 4:1. The two-phase conversion circuit 201 can increase the upper limit of the output current I2 and reduce the ripple of the input current I1.

[0054] Since the voltage stress on the switches (Q1~Q4) is reduced to half of the input voltage (V1•1 / 2), the multiphase switching circuit 200 can use low-voltage switches, thereby reducing on-resistance and cost. Furthermore, the voltage across the coupling inductors is reduced to (V1•1 / 2 - V2), and the current flowing through each inductor is half of the output current (1 / 2‧I2). Therefore, the coupling inductor Lc1 can use an inductor with a smaller size, lower inductance value, lower impedance, and lower power consumption.

[0055] In switching state 3 shown in Figure 6, the first lower bridge switch Q2 and the second lower bridge switch Q4 are turned on, the first upper bridge switch Q1 and the second upper bridge switch Q3 are turned off, inductors L1 and L2 are demagnetized, and inductor currents iL1 and iL2 flow from the ground potential to the output voltage (V2). In one embodiment, the operation of the adjustment mode can be achieved by periodically operating in switching state 3 with an appropriate duty cycle.

[0056] Figure 7 shows the small signal circuit model corresponding to switching state 1 in Figure 4. When Lmz is much larger than Lk1 and Lk2, the equivalent leakage inductance of the coupling inductor is equal to Lk1 and Lk2 in series. At this time, C1, Lk1, and Lk2 are connected in series between the input voltage (V1) and the output voltage (V2). The resonant frequency fres of the switching circuit can be estimated by the following formula:

[0057] Figure 8 shows the small signal circuit model of switching state 2 in Figure 5. When Lmz is much larger than Lk1 and Lk2, C1, Lk1, and Lk2 are connected in series between the reference ground and the output voltage V2. The resonant frequency of switching state 2 is the same as that of the circuit model in Figure 7.

[0058] Figure 9 shows the operation signal waveforms corresponding to a preferred embodiment of the multiphase switching circuit shown in Figure 3. The multiphase switching circuit of this embodiment includes two main switching states: switching state 1 and switching state 2. Switching control signals G1 and G4 control switches Q1 and Q4 respectively, while switching control signals G2 and G3 control switches Q2 and Q3 respectively. The switching control signals G1 and G4 are in phase and out of phase with the switching control signals G2 and G3.

[0059] During the time period from t0 to t1, the switching circuit is in switching state 1, with the first upper bridge switch Q1 and the second lower bridge switch Q4 turned on, and the first lower bridge switch Q2 and the second upper bridge switch Q3 turned off. When the inductor current (iL2 / iL1) is lower than the zero current threshold Ith, the switching control signals G1 and G4 are disabled (e.g., low level) to turn off the first upper bridge switch Q1 and the second lower bridge switch Q4. The preset zero current threshold Ith is a current threshold close to 0.

[0060] During the time period from t2 to t3, the multiphase conversion circuit is in switching state 2, the first upper bridge switch Q1 and the second lower bridge switch Q4 are turned off, and the first lower bridge switch Q2 and the second upper bridge switch Q3 are turned on. When the inductor current (iL2 / iL1) is lower than the preset zero current threshold Ith, the switching control signals G2 and G3 are disabled to turn off the first lower bridge switch Q2 and the second upper bridge switch Q3.

[0061] Furthermore, the time periods t1 to t2 and t3 to t4 are the idle time between switching state 1 and switching state 2. It is worth noting that in this embodiment, the inductor current iL1 is slightly greater than iL2 during t1 to t2, while the opposite is true between t3 and t4. From another perspective, the difference between the inductor currents iL2 and iL1, as shown in Figure 9, corresponds to the magnetizing current iLmz. In addition, in this embodiment, the multiphase switching circuit operates in resonant mode, and the switching period Tsw shown in Figure 9 corresponds to the resonant period, while the switching period between the inductor currents iL2 and iL1 is Tsw•1 / 2.

[0062] Figure 10 shows the direction of the excitation current during the time period t1 to t2 corresponding to Figure 9. When the first upper bridge switch Q1 and the second lower bridge switch Q4 are turned off, the excitation current (iLmz) flows to the second upper bridge switch Q3 (as shown by the gray arrow line) to release the parasitic capacitance of the second upper bridge switch Q3, thereby realizing the zero voltage switching (ZVS) of the second upper bridge switch Q3.

[0063] Figure 11 shows the direction of the excitation current during the time period t3 to t4 corresponding to Figure 9. When the first lower bridge switch Q2 and the second upper bridge switch Q3 are turned off, the excitation current (iLmz) flows to the first upper bridge switch Q1 (as shown by the gray arrow line) to release the parasitic capacitance of the first upper bridge switch Q1, thereby realizing the zero voltage switching (ZVS) of the first upper bridge switch Q1.

[0064] Figure 12 shows a specific embodiment of the current sensing circuit in the multiphase conversion circuit of the present invention, used to generate a sensing current signal on the coupled inductor. Inductors L1 and L2 respectively include parasitic DC resistances DCR1 and DCR2. The first current sensing circuit includes a sensing resistor Rx1 and a sensing capacitor Cx1; the second current sensing circuit includes a sensing resistor Rx2 and a sensing capacitor Cx2. The sensing resistor Rx1 and the sensing capacitor Cx1 are connected in series, and the series branch is coupled in parallel to the inductor L1 (including DCR1). The sensing resistor Rx2 and the sensing capacitor Cx2 are connected in series, and the series branch is coupled in parallel to the inductor L2 (including DCR2). When the time constants (L1, DCR1) and (Rx1, Cx1) are matched, the inductor current iL1 can be sensed by sensing the voltage of capacitor Cx1. Here, L1 and DCR1 represent the inductance value of inductor L1 and the resistance value of DCR1, respectively. Rx1 and Cx1 represent the resistance value of sensing resistor Rx1 and the capacitance value of sensing capacitor Cx1, respectively. The same logic applies to inductor L2. Amplifiers 181 and 182 are used to amplify the voltages of sensing capacitors Cx1 and Cx2, respectively, to generate current sensing signals SiL1 and SiL2. The summed current signal SiL is the sum of all inductor current signals (such as SiL1 and SiL2).

[0065] Figure 13 shows one embodiment of the multiphase conversion circuit of the present invention. The multiphase conversion circuit 300 includes two parallel-operating 4:1 two-phase conversion circuits 301 and 302, each of which corresponds, for example, to the two-phase conversion circuit 201 of Figure 3. In one embodiment, both two two-phase conversion circuits 301 and 302 operate in resonant mode to achieve soft switching of ZCS and ZVS. In one embodiment, the two two-phase sub-conversion circuits 301 and 302 are interleaved, for example, the switching time of the first upper bridge switch Q5 is phase-shifted by 180 degrees relative to the switching time of the first upper bridge switch Q1, thereby further reducing the ripple of the input current. Both branches of the coupling inductor Lc1 and both branches of the coupling inductor Lc2 are connected to the output voltage (V2) to provide a high output current I2. In other embodiments, the parallel-operating two-phase conversion circuits can be extended to more phases. In one embodiment, the corresponding on / off relationships in any two adjacent two-phase conversion circuits are switched in opposite phases.

[0066] Figure 14 shows an extended embodiment of the multiphase conversion circuit of the present invention. The multiphase conversion circuit 400 includes a two-phase conversion circuit 401 and an auxiliary switching capacitor conversion circuit 402. The two-phase conversion circuit 401 corresponds to the two-phase conversion circuit 201 in Figure 3. This embodiment adds an auxiliary switching capacitor conversion circuit 402 to the embodiment in Figure 3, which works in conjunction with the two-phase conversion circuit 401 to further reduce the ripple of the input current I1. The auxiliary switching capacitor conversion circuit 402 includes an auxiliary capacitor C2', a first auxiliary switch Q5', and a second auxiliary switch Q6'. As shown in Figure 14, the first auxiliary switch Q5' is coupled between the first conversion terminal TN11 and an auxiliary shunt node NC2', the second auxiliary switch Q6' is coupled between the auxiliary shunt node NC2' and the first switching node LX1, and the auxiliary capacitor C2' is coupled between the auxiliary shunt node NC2' and the second switching node LX2.

[0067] In this embodiment, in switching state 1 (charging phase), the first upper bridge switch Q1, the second lower bridge switch Q4 and the second auxiliary switch Q6' are turned on, thereby controlling the auxiliary capacitor C2' and the first inductor L1 to be connected in series between the ground potential and the second conversion terminal TN12, and controlling the first conversion capacitor C1 and the first inductor L1 to be connected in series between the first conversion terminal TN11 and the second conversion terminal TN12, and controlling the second inductor L2 to be connected between the ground potential and the second conversion terminal TN12. In switching state 2 (discharge phase), the first lower bridge switch Q2, the second upper bridge switch Q3, and the first auxiliary switch Q5' are turned on, thereby controlling the auxiliary capacitor C2' and the second inductor L2 to be connected in series between the first switching terminal TN11 and the second switching terminal TN12, and controlling the first switching capacitor C1 and the second inductor L2 to be connected in series between the ground potential and the second switching terminal TN12, and controlling the first inductor L1 to be connected in series between the ground potential and the first switching terminal TN11.

[0068] From one perspective, the multiphase conversion circuit 400 of Figure 14 can be viewed as a two-phase conversion circuit with two capacitors C1, C2' and a coupling inductor Lc1 cross-coupled and switched. This embodiment can further reduce the ripple of the input current.

[0069] In one embodiment, when the inductance value of the magnetizing inductor Lmz is much larger than the inductance values ​​of the leakage inductors Lk1 and Lk2, the resonant frequency fres of the switching circuit can be estimated by the following formula:

[0070] Figure 15 shows an embodiment of a multiphase conversion circuit with a voltage conversion ratio of 6:1 according to one of the present invention. The multiphase conversion circuit 500 includes a two-phase conversion circuit 501 and an auxiliary switching inductor conversion circuit 502. The two-phase conversion circuit 501 is similar to the two-phase conversion circuit 201 in Figure 3. In this embodiment, the two-phase conversion circuit 501 further includes a second conversion capacitor Cn1, coupled between the second upper bridge switch Q3 and the second switching node LX2, wherein the second upper bridge switch Q3 and the second conversion capacitor Cn1 are coupled to the second shunt node NC2.

[0071] The auxiliary switching inductive conversion circuit 502 includes an auxiliary upper bridge switch Q5”, an auxiliary lower bridge switch Q6”, and an auxiliary inductor L3”, wherein the auxiliary upper bridge switch Q5” is coupled between the second shunt node NC2 of the two-phase conversion circuit 501 and an auxiliary switching node LX3”, the auxiliary lower bridge switch Q6” is coupled between the auxiliary switching node LX3” and the ground potential, and the auxiliary inductor L3” is coupled between the auxiliary switching node LX3” and the second voltage V2.

[0072] In this switching state 1, the auxiliary upper bridge switch Q5” is turned on and the auxiliary lower bridge switch Q6” is turned off, thereby controlling the auxiliary inductor L3” to be electrically connected between the second shunt node NC2 of the two-phase conversion circuit 501 and the second voltage V2, so as to generate an auxiliary inductor current iL3 on the auxiliary inductor L3”. On the other hand, in this switching state 2, the auxiliary lower bridge switch Q6” is turned on and the auxiliary upper bridge switch Q5” is turned off, thereby controlling the auxiliary inductor L3” to be electrically connected between the ground potential and the second voltage V2. In this embodiment, the multiphase conversion circuit 500 achieves a voltage conversion ratio of 6:1 by means of the coordinated switching operation of the auxiliary switching inductor conversion circuit 502 and the two-phase conversion circuit 501, wherein in steady state, the DC component of the voltage across the first conversion capacitor C1 is V1•2 / 3 and the DC component of the voltage across the second conversion capacitor Cn1 is V1•1 / 3.

[0073] Figure 16 shows an embodiment of a multiphase conversion circuit with a voltage conversion ratio of 8:1 according to the present invention. The multiphase conversion circuit 600 includes two-phase conversion circuits 601 and 602, each including corresponding first and second conversion terminals. Specifically, the two-phase conversion circuit 601 includes first and second conversion terminals TN11 and TN12, and the two-phase conversion circuit 602 includes first and second conversion terminals TN21 and TN22. The two-phase conversion circuit 601 in this embodiment corresponds to the two-phase conversion circuit 501 shown in Figure 15, and the two-phase conversion circuit 602 corresponds to the two-phase conversion circuit 201 shown in Figure 3. In this embodiment, the first and second conversion terminals TN11 and TN12 of the two-phase conversion circuit 601 are respectively coupled to a first voltage V1 and a second voltage V2, and the first and second conversion terminals TN21 and TN22 of the two-phase conversion circuit 602 are respectively coupled to the second shunt node NC2 of the two-phase conversion circuit 601 and the second voltage V2.

[0074] In one embodiment, the multiphase conversion circuit 600 also includes two main switching states, which may correspond to switching state 1 and switching state 2 in the embodiment of FIG3. In switching state 1, the first upper bridge switches Q1, Q5 and the second lower bridge switches Q4, Q8 are turned on, while the first lower bridge switches Q2, Q6 and the second upper bridge switches Q3, Q7 are turned off. In switching state 2, the first upper bridge switches Q1, Q5 and the second lower bridge switches Q4, Q8 are turned off, while the first lower bridge switches Q2, Q6 and the second upper bridge switches Q3, Q7 are turned on. Specifically, in switching state 1, the first switching capacitors C1 and C2 are charged by the input voltage V1 and the voltage of the second switching capacitor Cn1, respectively. Inductors L1 and L3 are energized through the first switching capacitors C1 and C2 by the difference between the voltages (V1 - Vc1) and (Vcn1 - Vc2) on the corresponding first switching nodes LX1 and LX3 and the output voltage V2, respectively, to generate inductor currents iL1, iL2, iL3, and iL4 and magnetizing currents iLmz1 and iLmz3. Here, Vcn1 is the voltage across the second switching capacitor Cn1, and Vc2 is the voltage across the first switching capacitor C2. The output current I2 is equal to the sum of the inductor currents (I2 = iL1 + iL2 + iL3 + iL4).

[0075] Through the above configuration and periodic switching operation, in steady state, the DC components of the voltages Vc1 and Vc2 across the first switching capacitors C1 and C2 are V1•3 / 4 and V1•1 / 4, respectively, while the DC component of the voltage Vcn1 across the second switching capacitor Cn1 is V1•2 / 4. Furthermore, due to the further voltage division between the two branches of the coupling inductor Lc1 and the two branches of the coupling inductor Lc2, the voltage conversion ratio between the input voltage V1 and the output voltage V2 reaches 8:1. In addition, since the multiphase conversion circuit 600 includes two two-phase conversion circuits, it is a four-phase conversion circuit, which can further increase the upper limit of the output current I2 and reduce the ripple of the input current I1.

[0076] In one embodiment, the multiphase conversion circuit 600 operates in resonant mode, thereby achieving zero-current switching and zero-voltage switching. In one embodiment, when the capacitance value of the second conversion capacitor Cn1 is much larger than the capacitance value of the first conversion capacitor C1 (e.g., Cn1 > 10 × C1), the second conversion capacitor Cn1 is a non-resonant capacitor, that is, the second conversion capacitor Cn1 does not participate in resonance. The first resonant frequency of the two-phase conversion circuit 601 is determined by the leakage inductance Lk1 and Lk2 of the corresponding first conversion capacitor C1 and the coupling inductor Lc1. The second resonant frequency of the two-phase conversion circuit 602 is determined by the leakage inductance Lk3 and Lk4 of the corresponding first conversion capacitor C2 and the coupling inductor Lc2. In a preferred embodiment, the first resonant frequency and the second resonant frequency can be configured to be equal.

[0077] Figure 17 shows an embodiment of a multiphase conversion circuit with a voltage conversion ratio of 10:1 according to the present invention. The multiphase conversion circuit 700 includes two-phase conversion circuits 701 and 702 and an auxiliary switching inductor conversion circuit 703. This embodiment can be regarded as an extension of the embodiment of Figure 16 by adding an auxiliary switching inductor conversion circuit as shown in Figure 15. The two-phase conversion circuits 701 and 702 can correspond to the two-phase conversion circuits 601 and 602 of Figure 16, while the auxiliary switching inductor conversion circuit 703 can correspond to the auxiliary switching inductor conversion circuit 502 of Figure 15. The two-phase conversion circuit 702 also includes a second conversion capacitor Cn2. The auxiliary switching inductor conversion circuit 703 is coupled between the second shunt node NC4 corresponding to the two-phase conversion circuit 702 and the second voltage V2. Other operational details can be deduced from Figures 6 and 16, and will not be repeated here.

[0078] Through the above configuration and periodic switching operation, in steady state, the DC components of the voltages Vc1 and Vc2 across the first switching capacitors C1 and C2 are V1•4 / 5 and V1•2 / 5, respectively, while the DC components of the voltages Vcn1 and Vcn2 across the second switching capacitors Cn1 and Cn2 are V1•3 / 5 and V1•1 / 5, respectively. Furthermore, due to the further voltage division between the two branches of the coupling inductor Lc1 and the two branches of the coupling inductor Lc2, the voltage conversion ratio between the input voltage V1 and the output voltage V2 reaches 10:1. In addition, since the multiphase conversion circuit 700 includes two two-phase conversion circuits and one auxiliary switching inductor conversion circuit, it is a five-phase conversion circuit, which can further increase the upper limit of the output current I2 and reduce the ripple of the input current I1.

[0079] In one embodiment, the multiphase conversion circuit 700 operates in resonant mode, thereby achieving zero-current switching and zero-voltage switching. In one embodiment, when the capacitance values ​​of the second conversion capacitors Cn1 and Cn2 are much larger than the capacitance values ​​of the corresponding first conversion capacitors C1 and C2, the second conversion capacitors Cn1 and Cn2 are non-resonant capacitors, and the resonant frequencies of the two-phase conversion circuits 701 and 702 are determined by the capacitance values ​​of the corresponding first conversion capacitors C1 and C2 and the inductance values ​​of the corresponding leakage inductors, respectively.

[0080] Figure 18 shows an embodiment of a multiphase conversion circuit with a voltage conversion ratio of 12:1 according to the present invention. The multiphase conversion circuit 800 includes two-phase conversion circuits 801, 802, and 803. This embodiment can be considered an extension of the embodiment of Figure 16. Two-phase conversion circuits 801 and 802 correspond to two-phase conversion circuit 601 of Figure 16, while two-phase conversion circuit 803 corresponds to two-phase conversion circuit 602 of Figure 16. Two-phase conversion circuit 802 further includes a second conversion capacitor Cn2. In this embodiment, the first and second conversion terminals TN11 and TN12 of the two-phase conversion circuit 801 are respectively coupled to the first voltage V1 and the second voltage V2. The first and second conversion terminals TN21 and TN22 of the two-phase conversion circuit 802 are respectively coupled to the second shunt node NC2 of the two-phase conversion circuit 801 and the second voltage V2. The first and second conversion terminals TN31 and TN32 of the two-phase conversion circuit 803 are respectively coupled to the second shunt node NC4 of the two-phase conversion circuit 803 and the second voltage V2. Other operational details can be deduced from Figures 15 and 16, and will not be repeated here.

[0081] Through the above configuration and periodic switching operation, in steady state, the DC components of the voltage across the first switching capacitors C1, C2, and C3 are V1.5 / 6, V1.3 / 6, and V1.3 / 6, respectively, while the DC components of the voltage across the second switching capacitors Cn1 and Cn2 are V1.4 / 6 and V1.2 / 6, respectively. Furthermore, due to the further voltage division by the coupling inductor, the voltage conversion ratio between the input voltage V1 and the output voltage V2 reaches 12:1. Other characteristics can be deduced from the aforementioned embodiments.

[0082] Furthermore, depending on different needs, the multiphase conversion circuit can be expanded to include more even or odd phases by means of the configuration and operation methods of the aforementioned embodiments. For example, the multiphase conversion circuit of FIG17 can be expanded by analogy to include three or more two-phase conversion circuits and an auxiliary switching inductor conversion circuit, and the multiphase conversion circuit of FIG18 can be expanded by analogy to include four or more two-phase conversion circuits.

[0083] In an embodiment having M two-phase conversion circuits (as shown in Figure 16 or Figure 18), in steady state, the DC component of the voltage across the first conversion capacitor of each of the first to k two-phase conversion circuits is (2M-(2k-1)) / 2M of the first voltage V1, the DC component of the voltage across the second conversion capacitor of each two-phase conversion circuit is (2M-2k) / 2M of the first voltage V1, and the voltage conversion ratio between the first voltage V1 and the second voltage V2 is 2M•2:1, where k=1~M, and M is greater than or equal to 2.

[0084] On the other hand, in an embodiment having M' two-phase conversion circuits and further including an auxiliary switching inductor conversion circuit (as shown in FIG15 or FIG17), in steady state, the DC component of the voltage across the first conversion capacitor of each of the first to k' two-phase conversion circuits is ((2M'+1)-(2k'-1)) / (2M'+1) of the first voltage V1, and the DC component of the voltage across the second conversion capacitor of each two-phase conversion circuit is ((2M'+1)-2k') / (2M'+1) of the first voltage V1. The voltage conversion ratio of the first voltage V1 to the second voltage V2 is (2M'+1)•2:1, where k'=1~M', and M' is greater than or equal to 1.

[0085] The present invention has been described above with reference to preferred embodiments. However, the above description is only for the purpose of enabling those skilled in the art to easily understand the content of the present invention and is not intended to limit the broadest scope of the present invention. The various embodiments described are not limited to individual application and can also be combined. For example, two or more embodiments can be used in combination, and some components in one embodiment can be used to replace corresponding components in another embodiment. Furthermore, under the same spirit of the present invention, those skilled in the art can conceive of various equivalent changes and combinations. For example, the present invention's statement of "processing or calculating based on a signal or generating an output result" is not limited to the signal itself, but also includes, when necessary, performing voltage-to-current conversion, current-to-voltage conversion, and / or proportional conversion on the signal, and then processing or calculating based on the converted signal to generate an output result. Therefore, under the same spirit of the present invention, those skilled in the art can conceive of various equivalent changes and combinations, and there are many combinations, which will not be listed here. Therefore, the scope of the present invention should cover the above and all other equivalent changes. [Simplified Explanation of the Diagram]

[0026] Figure 1 is a circuit diagram showing a prior art two-phase buck converter circuit.

[0027] Figure 2 is a circuit diagram showing a multiphase conversion circuit according to one embodiment of the present invention.

[0028] Figure 3 is a circuit diagram showing a multiphase conversion circuit according to one embodiment of the present invention.

[0029] Figures 4-6 show schematic diagrams of several electrical connection states of the multiphase conversion circuit embodiment shown in Figure 3.

[0030] Figure 7 shows the small signal circuit model corresponding to switching state 1 in Figure 4.

[0031] Figure 8 shows the small signal circuit model corresponding to switching state 2 in Figure 5.

[0032] FIG9 is a waveform diagram of the operation signal corresponding to the multiphase conversion circuit shown in FIG3 according to a preferred embodiment of the present invention.

[0033] Figure 10 shows the direction of the excitation current during the time period from t1 to t2 corresponding to Figure 9.

[0034] Figure 11 shows the direction of the excitation current during the time period from t3 to t4 corresponding to Figure 9.

[0035] Figure 12 is a circuit diagram showing the current sensing circuit in a multiphase conversion circuit according to a specific embodiment of the present invention.

[0036] Figure 13 is a circuit diagram showing a multiphase conversion circuit according to one embodiment of the present invention.

[0037] Figure 14 is a circuit diagram of a multiphase conversion circuit according to an extended embodiment of the present invention.

[0038] Figure 15 is a circuit diagram showing a multiphase conversion circuit with a voltage conversion ratio of 6:1 according to one embodiment of the present invention.

[0039] Figure 16 is a circuit diagram showing a multiphase conversion circuit with a voltage conversion ratio of 8:1 according to another embodiment of the present invention.

[0040] Figure 17 is a circuit diagram showing a multiphase conversion circuit with a voltage conversion ratio of 10:1 according to another embodiment of the present invention.

[0041] Figure 18 is a circuit diagram showing a multiphase conversion circuit with a voltage conversion ratio of 12:1 according to another embodiment of the present invention.

Claims

1. A multiphase conversion circuit comprising at least one two-phase conversion circuit for power conversion between a first voltage and a second voltage, wherein each of the at least one two-phase conversion circuit comprises: A first switching terminal and a second switching terminal; a complex switch; A first conversion capacitor; The system also includes a coupling inductor comprising a first inductor and a second inductor, the first inductor and the second inductor being reverse-coupled, and the coupling inductor having an equivalent leakage inductance. The complex switch controls the electrical connection between the first switching capacitor, the first inductor, and the second inductor, and between the first voltage and the second voltage, thereby generating a complex electrical connection state, so that the first switching capacitor alternately switches between a charging phase with a charging time and a discharging phase with a discharging time. During the charging phase, the complex switch controls the first switching capacitor and the first inductor to be connected in series between the first switching terminal and the second switching terminal, so that a first inductor current is generated in the first inductor, and a second inductor current is generated through electromagnetic coupling to the second inductor. In the discharge phase, the complex switch controls the first conversion capacitor and the second inductor to be connected in series between the ground potential and the second conversion terminal, so as to generate the second inductor current and generate the first inductor current through electromagnetic coupling; wherein the at least one two-phase conversion circuit includes a first two-phase conversion circuit, wherein the first conversion terminal is coupled to the first voltage and the second conversion terminal is coupled to the second voltage; wherein each of the at least one two-phase conversion circuit includes: a first upper bridge switch coupled between the first conversion terminal and a first shunt node; the first conversion capacitor coupled between the first shunt node and a first switching node; a first lower bridge switch coupled between the first switching node and the ground potential; the first inductor coupled between the first switching node and the second conversion terminal; and a second upper bridge switch coupled between the first shunt node and the second switching node; A second lower bridge switch is coupled between the second switching node and the ground potential; and a second inductor is coupled between the second switching node and the second conversion terminal; wherein, in the charging phase, the first upper bridge switch is turned on, thereby controlling the first conversion capacitor and the first inductor to be connected in series between the first conversion terminal and the second conversion terminal; wherein, in the discharging phase, the first lower bridge switch and the second upper bridge switch are turned on, thereby controlling the first conversion capacitor and the second inductor to be connected in series between the ground potential and the second conversion terminal; wherein the at least one two-phase conversion circuit includes a first to Mth two-phase conversion circuits arranged in sequence, wherein M is greater than or equal to 2; wherein the first conversion terminal corresponding to the kth two-phase conversion circuit is coupled to a second shunt node of the (k-1)th two-phase conversion circuit, and the second conversion terminal corresponding to the kth two-phase conversion circuit is coupled to the second voltage, wherein k = 2~M; Each of the first to the (M-1)th biphase conversion circuits further includes a second conversion capacitor, coupled between the second upper bridge switch and the second switching node, and coupled together with the second upper bridge switch to the corresponding second shunt node;The on / off states of the first to Mth two-phase switching circuits are switched in phase with each other.

2. The multiphase conversion circuit as claimed in claim 1, wherein the charging time and the discharging time are respectively half the resonant period of the leakage inductance of the first conversion capacitor and the coupling inductor, so as to control the first conversion capacitor and the coupling inductor to resonate, thereby performing power conversion.

3. The multiphase conversion circuit as described in claim 1, wherein the capacitance value of the second conversion capacitor is more than 10 times greater than the capacitance value of the first conversion capacitor, thereby the second conversion capacitor does not participate in resonance, and only the first conversion capacitor resonates with the first inductor or the second inductor.

4. The multiphase conversion circuit as described in claim 1, further comprising an auxiliary switching inductor conversion circuit, wherein the auxiliary switching inductor conversion circuit includes: An auxiliary upper bridge switch, an auxiliary lower bridge switch, and an auxiliary inductor are provided. The auxiliary upper bridge switch is coupled between the second shunt node and an auxiliary switching node of the Mth two-phase conversion circuit. The auxiliary lower bridge switch is coupled between the auxiliary switching node and the ground potential. The auxiliary inductor is coupled between the auxiliary switching node and the second voltage. The auxiliary upper bridge switch is further turned on during the charging phase, thereby controlling the auxiliary inductor to be electrically connected between the second shunt node and the second voltage of the Mth two-phase conversion circuit, so as to generate an auxiliary inductor current on the auxiliary inductor.

5. The multiphase conversion circuit as described in claim 1, wherein the first inductor and the second inductor have the same number of turns.

6. The multiphase conversion circuit as claimed in claim 1, wherein the multiple electrical connection states further include an optional freewheeling phase, wherein in the freewheeling phase, the multiple switches control the first inductor and the second inductor to be electrically connected between the ground potential and the second conversion terminal, thereby demagnetizing the first inductor and the second inductor.

7. The multiphase switching circuit as claimed in claim 1, wherein in the charging phase, when the first inductor current flowing through the first inductor drops below a preset zero current threshold, the circuit switches to the discharging phase; or, in the discharging phase, when the second inductor current flowing through one of the second inductors drops below the preset zero current threshold, the circuit switches to the charging phase, thereby achieving zero current switching (ZCS) or zero voltage switching (ZVS).

8. The multiphase conversion circuit as described in claim 7, wherein at the point when the charging phase transitions to the discharging phase, the first inductor current is higher than the second inductor current, and the difference between the first inductor current and the second inductor current corresponds to an excitation current; wherein at the point when the discharging phase transitions to the charging phase, the second inductor current is higher than the first inductor current, and the difference between the second inductor current and the first inductor current corresponds to the excitation current.

9. The multiphase conversion circuit as claimed in claim 8, wherein a lag time is included when the charging phase and the discharging phase switch with each other, wherein during the lag time, the magnetizing current is used to achieve zero-voltage switching of the first upper bridge switch and / or the second upper bridge switch.

10. The multiphase conversion circuit as claimed in claim 1, wherein in steady state, the DC component of the voltage across the first conversion capacitor of each of the first to k' two-phase conversion circuits is (2M-(2k'-1)) / 2M of the first voltage, and the DC component of the voltage across the second conversion capacitor of each of the two-phase conversion circuits is (2M-2k') / 2M of the first voltage, where k'=1~M, and the voltage conversion ratio between the first voltage and the second voltage is 2M•2:

1.

11. The multiphase conversion circuit as claimed in claim 4, wherein in steady state, the DC component of the voltage across the first conversion capacitor of each of the first to k' two-phase conversion circuits is ((2M+1)-(2k'-1)) / (2M+1) of the first voltage, and the DC component of the voltage across the second conversion capacitor of each of the two-phase conversion circuits is ((2M+1)-2k') / (2M+1) of the first voltage, where k'=1~M, and the voltage conversion ratio between the first voltage and the second voltage is (2M+1)•2:

1.

12. The multiphase conversion circuit as claimed in claim 1, wherein the ratio between the second voltage and the first voltage is adjusted by controlling the duty cycle and / or switching frequency of the charging phase and / or the discharging phase.

13. The multiphase conversion circuit as claimed in claim 1, wherein the multiphase conversion circuit includes a first current sensing circuit and a second current sensing circuit, which are respectively connected in parallel to the first inductor and the second inductor to generate a first current sensing signal and a second current sensing signal to indicate the first inductor current and the second inductor current, wherein the first current sensing circuit and the second current sensing circuit each include a sensing resistor and a sensing capacitor.

14. The multiphase switching circuit as claimed in claim 1, wherein during resonant operation, the first switching capacitor is net charged in the charging phase and net discharged in the discharging phase.

15. A multiphase conversion circuit comprising at least one two-phase conversion circuit for power conversion between a first voltage and a second voltage, wherein each of the at least one two-phase conversion circuit comprises: A first switching terminal and a second switching terminal; a complex switch; A first conversion capacitor; The system also includes a coupling inductor comprising a first inductor and a second inductor, the first inductor and the second inductor being reverse-coupled, and the coupling inductor having an equivalent leakage inductance. The complex switch controls the electrical connection between the first switching capacitor, the first inductor, and the second inductor, and between the first voltage and the second voltage, thereby generating a complex electrical connection state, so that the first switching capacitor alternately switches between a charging phase with a charging time and a discharging phase with a discharging time. During the charging phase, the complex switch controls the first switching capacitor and the first inductor to be connected in series between the first switching terminal and the second switching terminal, so that a first inductor current is generated in the first inductor, and a second inductor current is generated through electromagnetic coupling to the second inductor. In the discharge phase, the complex switch controls the first conversion capacitor and the second inductor to be connected in series between the ground potential and the second conversion terminal, so as to generate the second inductor current and generate the first inductor current through electromagnetic coupling; wherein the at least one two-phase conversion circuit includes a first two-phase conversion circuit, wherein the first conversion terminal is coupled to the first voltage and the second conversion terminal is coupled to the second voltage; wherein each of the at least one two-phase conversion circuit includes: a first upper bridge switch coupled between the first conversion terminal and a first shunt node; the first conversion capacitor coupled between the first shunt node and a first switching node; a first lower bridge switch coupled between the first switching node and the ground potential; the first inductor coupled between the first switching node and the second conversion terminal; and a second upper bridge switch coupled between the first shunt node and the second switching node; A second lower bridge switch is coupled between the second switching node and the ground potential; and a second inductor is coupled between the second switching node and the second switching terminal; wherein, in the charging phase, the first upper bridge switch is turned on, thereby controlling the first switching capacitor and the first inductor to be connected in series between the first switching terminal and the second switching terminal; wherein, in the discharging phase, the first lower bridge switch and the second upper bridge switch are turned on, thereby controlling the first switching capacitor and the second inductor to be connected in series between the ground potential and the second switching terminal; wherein each of the at least one two-phase switching circuit further includes: an auxiliary switching capacitor switching circuit, including an auxiliary capacitor, a first auxiliary switch and a second auxiliary switch, wherein the first auxiliary switch is coupled between the first switching terminal and an auxiliary shunt node, the second auxiliary switch is coupled between the auxiliary shunt node and the first switching node, and the auxiliary capacitor is coupled between the auxiliary shunt node and the second switching node;In the charging phase, the second auxiliary switch is turned on, thereby controlling the auxiliary capacitor and the first inductor to be connected in series between the ground potential and the second switching terminal, and controlling the first switching capacitor and the first inductor to be connected in series between the first switching terminal and the second switching terminal, and controlling the second inductor to be connected between the ground potential and the second switching terminal; in the discharging phase, the first auxiliary switch is turned on, thereby controlling the auxiliary capacitor and the second inductor to be connected in series between the first switching terminal and the second switching terminal, and controlling the first switching capacitor and the second inductor to be connected in series between the ground potential and the second switching terminal, and controlling the first inductor to be connected between the ground potential and the first switching terminal.

16. A multiphase conversion circuit comprising at least one two-phase conversion circuit for power conversion between a first voltage and a second voltage, wherein each of the at least one two-phase conversion circuit comprises: A first switching terminal and a second switching terminal; a complex switch; A first conversion capacitor; The system also includes a coupling inductor comprising a first inductor and a second inductor, the first inductor and the second inductor being reverse-coupled, and the coupling inductor having an equivalent leakage inductance. The complex switch controls the electrical connection between the first switching capacitor, the first inductor, and the second inductor, and between the first voltage and the second voltage, thereby generating a complex electrical connection state, so that the first switching capacitor alternately switches between a charging phase with a charging time and a discharging phase with a discharging time. During the charging phase, the complex switch controls the first switching capacitor and the first inductor to be connected in series between the first switching terminal and the second switching terminal, so that a first inductor current is generated in the first inductor, and a second inductor current is generated through electromagnetic coupling to the second inductor. In the discharge phase, the complex switch controls the first conversion capacitor and the second inductor to be connected in series between the ground potential and the second conversion terminal, so as to generate the second inductor current and generate the first inductor current through electromagnetic coupling; wherein the at least one two-phase conversion circuit includes a first two-phase conversion circuit, wherein the first conversion terminal is coupled to the first voltage and the second conversion terminal is coupled to the second voltage; wherein each of the at least one two-phase conversion circuit includes: a first upper bridge switch coupled between the first conversion terminal and a first shunt node; the first conversion capacitor coupled between the first shunt node and a first switching node; a first lower bridge switch coupled between the first switching node and the ground potential; the first inductor coupled between the first switching node and the second conversion terminal; and a second upper bridge switch coupled between the first shunt node and the second switching node; A second lower bridge switch is coupled between the second switching node and the ground potential; and a second inductor is coupled between the second switching node and the second conversion terminal; wherein, in the charging phase, the first upper bridge switch is turned on, thereby controlling the first conversion capacitor and the first inductor to be connected in series between the first conversion terminal and the second conversion terminal; wherein, in the discharging phase, the first lower bridge switch and the second upper bridge switch are turned on, thereby controlling the first conversion capacitor and the second inductor to be connected in series between the ground potential and the second conversion terminal; wherein the first two-phase conversion circuit further includes a second conversion capacitor, coupled between the second upper bridge switch and the second switching node, and coupled together with the second upper bridge switch to a second shunt node; The multiphase conversion circuit further includes an auxiliary switching inductor conversion circuit, which includes an auxiliary upper bridge switch, an auxiliary lower bridge switch, and an auxiliary inductor. The auxiliary upper bridge switch is coupled between the second shunt node and the auxiliary switching node of the first two-phase conversion circuit, the auxiliary lower bridge switch is coupled between the auxiliary switching node and the ground potential, and the auxiliary inductor is coupled between the auxiliary switching node and the second voltage.The auxiliary bridge switch is turned on during the charging phase, thereby controlling the auxiliary inductor to be electrically connected between the second shunt node and the second voltage of the first two-phase conversion circuit, so as to generate an auxiliary inductor current on the auxiliary inductor.

17. A multiphase conversion circuit comprising at least one two-phase conversion circuit for power conversion between a first voltage and a second voltage, wherein each of the at least one two-phase conversion circuit comprises: A first switching terminal and a second switching terminal; a complex switch; A first conversion capacitor; The system also includes a coupling inductor comprising a first inductor and a second inductor, the first inductor and the second inductor being reverse-coupled, and the coupling inductor having an equivalent leakage inductance. The complex switch controls the electrical connection between the first switching capacitor, the first inductor, and the second inductor, and between the first voltage and the second voltage, thereby generating a complex electrical connection state, so that the first switching capacitor alternately switches between a charging phase with a charging time and a discharging phase with a discharging time. During the charging phase, the complex switch controls the first switching capacitor and the first inductor to be connected in series between the first switching terminal and the second switching terminal, so that a first inductor current is generated in the first inductor, and a second inductor current is generated through electromagnetic coupling to the second inductor. In the discharge phase, the multiple switches control the first conversion capacitor and the second inductor to be connected in series between the ground potential and the second conversion terminal, so as to generate the second inductor current and generate the first inductor current through electromagnetic coupling; the at least one two-phase conversion circuit includes a first two-phase conversion circuit, the first conversion terminal of which is coupled to the first voltage and the second conversion terminal of which is coupled to the second voltage; the multiple electrical connection state further includes an optional freewheeling phase, in which the multiple switches control the first inductor and the second inductor to be connected between the ground potential and the second conversion terminal, thereby demagnetizing the first inductor and the second inductor.

18. The multiphase conversion circuit as claimed in claim 17, wherein each of the at least one two-phase conversion circuit comprises: A first bridge switch is coupled between the first switching terminal and a first shunt node; The first switching capacitor is coupled between the first shunt node and a first switching node; A first lower bridge switch is coupled between the first switching node and the ground potential; a first inductor is coupled between the first switching node and the second switching terminal; a second upper bridge switch is coupled between the first shunt node and the second switching node; a second lower bridge switch is coupled between the second switching node and the ground potential. The second inductor is coupled between the second switching node and the second conversion terminal; wherein, in the charging phase, the first upper bridge switch is turned on, thereby controlling the first conversion capacitor and the first inductor to be connected in series between the first conversion terminal and the second conversion terminal; wherein, in the discharging phase, the first lower bridge switch and the second upper bridge switch are turned on, thereby controlling the first conversion capacitor and the second inductor to be connected in series between the ground potential and the second conversion terminal.

19. The multiphase conversion circuit as claimed in claim 18, wherein the at least one two-phase conversion circuit comprises a first to a Qth two-phase conversion circuit arranged in sequence, wherein Q is greater than 1, wherein the first conversion terminal of each of the first to the Qth two-phase conversion circuits is coupled to the first voltage, and the second conversion terminal is coupled to the second voltage; wherein, The corresponding on / off relationships in any two adjacent two-phase switching circuits are switched in opposite phases.

20. The multiphase conversion circuit as claimed in claim 19, wherein in steady state, the DC component of the voltage across the first conversion capacitor of each of the first to Qth two-phase conversion circuits is 1 / N of the first voltage, and the voltage conversion ratio of the first voltage to the second voltage is 2N:1, where N is a positive integer greater than or equal to 2.

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