Multi-phase switched-capacitor converter and control method thereof

Abstract

This invention discloses a multiphase switching capacitor converter for converting a first voltage to a second voltage or performing an inverse conversion. The converter comprises two sets of sub-converters connected in parallel between the input and output voltages. Each sub-converter includes a flying capacitor and multiple switches. Power conversion is performed between a first and a second switching phase by periodically switching the electrical connection between the flying capacitor and the voltage source. The two sets of sub-converters periodically alternate between the first and second system states, and an overlapping system state is introduced during the transition between the first and second system states, so that both sub-converters are simultaneously in the first switching phase, thereby ensuring uninterrupted current flow and reducing surges.

Description

Technical Field

[0001] This invention relates to switching power conversion technology, and more specifically, to a multiphase switching capacitor converter and its control method. Prior Technology

[0002] Power converters are widely used in various applications, including mobile devices. As device size and temperature constraints become increasingly stringent, the design requirements for high efficiency and high power density in power converters are becoming more critical. To address this need, the industry has proposed various architectures and control methods to improve efficiency and reduce losses.

[0003] For example, the paper "An SC Voltage Doubler with Pseudo-Continuous Output Regulation Using a Three-Stage Switchable Opamp," published in the IEEE Journal of Solid-State Circuits, Volume 42, Issue 6, 2007, discloses a voltage-doubling switching capacitor converter that utilizes two sets of flying capacitors and eight switches in a two-phase operation, as shown in Figure 1. This technology uses a non-overlapping clock for control, and while it can achieve multi-phase power conversion, improvements are still needed in terms of efficiency, surge, and electromagnetic interference suppression.

[0004] To overcome the limitations of the prior art, this invention proposes a multiphase switching capacitor converter that uses a controller to interleave the operating phases of multiple converters and incorporates a periodic switching mechanism with overlapping system states. This simultaneously achieves the following advantages: reduced input and output voltage surges and ripples, extended converter lifespan, improved electromagnetic interference (EMI) performance, zero-voltage switching (ZVS) and zero-current switching (ZCS) to improve efficiency and thermal performance, and support for higher power conversion requirements. Summary of the Invention

[0005] From one perspective, the present invention provides a multiphase switching capacitor converter for converting a first voltage to a second voltage, or vice versa. The multiphase switching capacitor converter includes a first sub-converter and a second sub-converter coupled between the first voltage and the second voltage; each of the first and second sub-converters includes a flying capacitor and a plurality of switches for periodically switching the electrical connection between the flying capacitor and the first and second voltages between a first switching phase and a second switching phase; wherein in the first switching phase, the flying capacitor is electrically connected to the first voltage through the switching of the plurality of switches to form a current path, and in the second switching phase, the flying capacitor is electrically disconnected from the first voltage through the switching of the plurality of switches; the multiphase switching capacitor converter periodically switches... Between the first system state and the second system state, a power conversion is performed between a first voltage and a second voltage; in the first system state, the first sub-converter is in a first switching phase and the second sub-converter is in a second switching phase; in the second system state, the first sub-converter is in the second switching phase and the second sub-converter is in the first switching phase; when switching from the first system state to the second system state, or from the second system state to the first system state, an overlapping system state is first passed to maintain the continuity of a first current corresponding to the first voltage and avoid surges; in the overlapping system state, the first sub-converter and the second sub-converter are simultaneously in the first switching phase.

[0006] In a preferred embodiment, the duration of the overlapping system state is less than 25% of the switching cycle of one of the multiphase switching capacitor converters.

[0007] In a preferred embodiment, each of the first sub-converter and the second sub-converter, when switching from the first switching phase to the second switching phase or from the second switching phase to the first switching phase, first undergoes a delay time to avoid short-circuit current between the multiple switches.

[0008] In a preferred embodiment, when each of the first sub-converter and the second sub-converter enters the first switching phase or the second switching phase, the first terminal of the flying capacitor is turned on before the second terminal to be electrically connected to the node corresponding to the first switching phase, forming the coupling relationship required for the first switching phase. In this way, the second terminal can gradually approach the zero voltage state and then be turned on to be electrically connected to the node corresponding to the first switching phase to achieve zero voltage switching. In the steady state, the terminal of the flying capacitor with the lower voltage corresponds to the first terminal; and / or, the terminal phase voltage difference of the flying capacitor corresponds to the first terminal, wherein the terminal phase voltage difference refers to the absolute value of the difference between the voltage levels of each terminal of the flying capacitor in the first switching phase and the second switching phase.

[0009] In a preferred embodiment, each of the first sub-converter and the second sub-converter includes a plurality of flying capacitors, wherein in a first switching phase, the plurality of flying capacitors sequentially complete corresponding electrical connections, such that the voltage changes at the first and second terminals of each flying capacitor gradually increase; and / or in a second switching phase, the plurality of flying capacitors sequentially complete corresponding electrical connections, such that the voltage changes at the first and second terminals of each flying capacitor gradually decrease.

[0010] In a preferred embodiment, when entering the first switching phase or the second switching phase, the first terminal of the speeding capacitor is switched to zero current to be electrically connected to the corresponding node.

[0011] In a preferred embodiment, the plurality of switches includes a first to a fourth switch, wherein: a first switch is coupled between a first voltage and a second terminal of a flying capacitor; a second switch is coupled between a first terminal of the flying capacitor and a second voltage; a third switch is coupled between a second terminal of the flying capacitor and the second voltage; and a fourth switch is coupled between a first terminal of the flying capacitor and a ground potential; in a first switching phase, the first and second switches are turned on, electrically connecting the flying capacitor between the first voltage and the second voltage, wherein the first voltage charges the flying capacitor and supplies power to the second voltage; in a second switching phase, the third and fourth switches are turned on, electrically connecting the flying capacitor in parallel with the second voltage, causing the flying capacitor to discharge to supply power to the second voltage.

[0012] In a preferred embodiment, the first switch turns on after the second switch turns on, and then turns on after a preset delay time to achieve zero voltage switching; and / or, the third switch turns on after the fourth switch turns on, and then turns on after a preset delay time to achieve zero voltage switching; or, after the second switch turns on, the first switch turns on when the voltage across it is lower than a threshold to achieve zero voltage switching; and / or, after the fourth switch turns on, the third switch turns on when the voltage across it is lower than a threshold to achieve zero voltage switching.

[0013] In a preferred embodiment, the voltage conversion ratio between the first voltage and the second voltage is 2:1.

[0014] In a preferred embodiment, the voltage conversion ratio between the first voltage and the second voltage is K:1, wherein each of the first sub-converter and the second sub-converter is a series-parallel switching capacitor converter and both have a complex number of flying capacitors, wherein K is a positive integer greater than or equal to 3.

[0015] In a preferred embodiment, the voltage conversion ratio between the first voltage and the second voltage is K:1, wherein each of the first sub-converter and the second sub-converter corresponds to a pipeline-type switched capacitor converter or a Dixon-type switched capacitor converter, and the voltage conversion ratio K is a positive integer greater than or equal to 4.

[0016] In a preferred embodiment, the switching capacitor converter includes an equivalent inductance between the first voltage and the flying capacitor, wherein the equivalent inductance causes a voltage surge in the event of a first current interruption.

[0017] From another perspective, the present invention provides a control method for power conversion between a first voltage and a second voltage, comprising: controlling each of two sets of sub-conversion units to periodically switch between a first switching phase and a second switching phase, wherein during the first switching phase, a flying capacitor is connected to the first voltage to form a current path to the second voltage, and during the second switching phase, the flying capacitor is disconnected from the first voltage; controlling the two sets of sub-conversion units to periodically switch between a first system state and a second system state, wherein the first system state corresponds to one sub-conversion unit of the two sets of sub-conversion units being in its corresponding first switching phase and the other sub-conversion unit being in its corresponding second switching phase, wherein the second system state is out of phase with the first state; and using an overlapping system state between the first system state and the second system state to ensure that the two sets of sub-conversion units are simultaneously in their corresponding first switching phases, thereby maintaining the continuity of a first current corresponding to the first voltage and avoiding surges.

[0018] In a preferred embodiment, the step of controlling each sub-conversion unit to periodically switch between the first switching phase and the second switching phase includes: each sub-conversion unit first undergoes a lag time between the corresponding first switching phase and the second switching phase, so as to avoid short-circuit current between the switching elements of each sub-conversion unit.

[0019] In a preferred embodiment, the step of controlling each sub-conversion unit to periodically switch between the first switching phase and the second switching phase includes: when each sub-conversion unit enters the first switching phase, preferentially turning on the electrical connection between a first terminal of a flying capacitor and the corresponding node, and delaying the turning on of the electrical connection between a second terminal and the corresponding node, thereby turning on the second terminal under conditions gradually approaching zero voltage to achieve zero voltage switching; wherein in steady state, the terminal of the flying capacitor with a lower voltage corresponds to the first terminal; and / or the terminal phase voltage difference of the flying capacitor corresponds to the first terminal, wherein the terminal phase voltage difference refers to the absolute value of the difference between the voltage levels of each terminal of the flying capacitor in the first switching phase and the second switching phase.

[0020] In a preferred embodiment, each of the sub-conversion units includes a complex number of flying capacitors, wherein the step of controlling each of the sub-conversion units to periodically switch between a first switching phase and a second switching phase further includes: in the first switching phase, sequentially connecting the electrical connections of the corresponding nodes of the complex flying capacitors, so that the voltage changes of the corresponding first terminal and second terminal gradually increase; in the second switching phase, sequentially connecting the electrical connections of the corresponding nodes of the complex flying capacitors, so that the voltage changes of the corresponding first terminal and second terminal gradually decrease.

[0021] The following detailed description through specific embodiments will make it easier to understand the purpose, technical content, features and effects achieved by this invention. Simple Explanation of the Diagram

[0022] Figure 1 shows a circuit diagram and control signal waveform of a prior art multiphase switching capacitor converter.

[0023] Figure 2 shows a schematic diagram of the circuit architecture of a multiphase switching capacitor converter according to one embodiment of the present invention.

[0024] Figure 3 shows a schematic diagram of a specific embodiment of the controller corresponding to Figure 2.

[0025] Figure 4 shows the control signal waveform corresponding to Figure 2.

[0026] Figure 5A shows a schematic diagram of the switching states corresponding to the overlapping system states in Figure 2.

[0027] Figure 5B shows a schematic diagram of the switching states corresponding to the first system state in Figure 2.

[0028] Figure 5C shows a schematic diagram of the switching states corresponding to the second system state in Figure 2.

[0029] Figure 6A shows the input and output current waveforms in the prior art non-overlapping control mode.

[0030] Figure 6B shows the input and output current waveforms when the control method of the present invention is used.

[0031] Figure 7 shows a schematic diagram of the switching control signal waveform and phase switching sequence according to an embodiment of the present invention.

[0032] Figure 8 shows a schematic diagram of the circuit configuration of an embodiment of the present invention under a 4:1 series-parallel architecture.

[0033] Figure 9 shows a schematic diagram of the circuit configuration of an embodiment of the present invention under a 4:1 pipeline architecture.

[0034] Figure 10 shows a schematic diagram of the circuit configuration of an embodiment of the present invention under a 4:1 Dickson architecture. Implementation

[0035] 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.

[0036] Figure 2 shows a schematic diagram of the circuit architecture of an embodiment of the present invention. The multiphase switching capacitor converter 200 includes a first sub-converter 210A and a second sub-converter 210B connected in parallel between a first voltage V1 and a second voltage V2. In this embodiment, each converter is a 2:1 step-down switching capacitor converter, including a flying capacitor (i.e., CFA or CFB) and multiple switches (i.e., Q1A~Q4A or Q1B~Q4B) to convert the first voltage V1 to the second voltage V2 through the periodic switching of the switches, forming a 2:1 switching capacitor voltage divider.

[0037] The multiphase switching capacitor converter 200 also includes a controller 220 for generating a switching control signal Ssw to control the operation of a first sub-converter 210A and a second sub-converter 210B. The first sub-converter 210A switches between its corresponding first switching phase PH1A and second switching phase PH2A, periodically switching the electrical connection between its internal flying capacitor and the first voltage V1 and the second voltage V2 through a plurality of switches to perform power conversion. Similarly, the second sub-converter 210B also operates between its corresponding first switching phase PH1B and second switching phase PH2B.

[0038] As shown in Figure 2, an equivalent inductance Ls is used to represent the sum of the power supply impedance of the input terminal (the terminal corresponding to the first voltage V1 in this embodiment), the circuit board traces, and the parasitic inductance of the wiring. If the input current (corresponding to the first current I1 corresponding to the first voltage V1 in this embodiment) is interrupted, a high voltage surge will be generated and may damage the switch.

[0039] In one embodiment, the first sub-converter 210A and the second sub-converter 210B are switched in approximately opposite phases. However, the present invention proposes a more refined switching method to avoid voltage surges in the input voltage (e.g., the first voltage V1 in this embodiment).

[0040] Regarding the overall operation of the multiphase switching capacitor converter 200, the controller 220 controls the multiphase switching capacitor converter 200 to periodically switch between a first system state, an overlapping system state, and a second system state. In the first system state, the first sub-converter 210A is in its first switching phase PH1A, and the second sub-converter 210B is in its second switching phase PH2B; in the second system state, the first sub-converter 210A is in its second switching phase PH2A, and the second sub-converter 210B is in its first switching phase PH1B; in the overlapping system state, both are in their respective first switching phases PH1A and PH1B.

[0041] In one embodiment, before switching to the first system state or the second system state, it is necessary to first pass through the overlapping system state to form a continuous current path between the input voltage and each sub-converter, thereby ensuring that the first current I1 is not interrupted, effectively suppressing voltage surges, improving the reliability, electromagnetic interference characteristics and service life of the converter, or reducing the electrical requirements of the switching elements, thus reducing costs.

[0042] The specific circuit operation and switching of the aforementioned first and second switching phases will be explained in detail in subsequent paragraphs.

[0043] It should be noted that the embodiments of the multiphase switching capacitor converter in this article are mainly demonstrated by the power conversion from a first voltage V1 to a second voltage V2 (that is, the first voltage V1 corresponds to the input voltage, the second voltage V2 corresponds to the output voltage, the first current I1 corresponds to the input current, and the second current I2 corresponds to the output current). In other embodiments, the multiphase switching capacitor converter of the present invention can also support the power conversion operation from the second voltage V2 to the first voltage V1.

[0044] Figure 3 shows a schematic diagram of a controller according to a specific embodiment of the present invention. The controller 220 includes a first OR gate 222A and a second OR gate 222B. The first OR gate 222A receives a clock signal Clock and a delayed clock signal Sd1, and generates a first switching control signal S1A and a third switching control signal S3A for the first sub-converter 210A through an inverter 223A. The second OR gate 222B receives an inverted clock signal Sckb and a delayed inverted clock signal Sd2, and generates a first switching control signal S1B and a third switching control signal S3B for the second sub-converter 210B through an inverter 223B, thereby controlling the multiphase switching capacitor converter 200 to periodically switch between the aforementioned system states. The aforementioned delayed clock signal Sd1 and inverted delayed clock signal Sd2 are obtained by delaying the clock signal Clock and inverting the clock signal Sckb by delay units 221A and 221B, respectively.

[0045] Figures 4 and 5A to 5C together illustrate the operating state of the multiphase switching capacitor converter 200 and the corresponding circuit switching operation during a switching cycle in one embodiment of the present invention. Figure 4 shows the waveform diagram corresponding to the control signal in Figure 2, while Figures 5A to 5C show the switching states of the circuit in Figure 2 under different conditions.

[0046] In this embodiment, the first sub-converter 210A is in its first switching phase PH1A from t0 to t3, and enters the second switching phase PH2A from t3 to t4. The second sub-converter 210B is in its second switching phase PH2B from t1 to t2, and in its first switching phase PH1B from t2 to t5. Tsw(t0~t4) represents one switching cycle.

[0047] The first and second switching phases of each sub-converter correspond to different electrical connections between the flying capacitor and the first voltage V1, the second voltage V2, or ground potential. Specifically, in the first switching phase PH1A or PH1B, the flying capacitor (CFA or CFB) is turned on through the first and second switches (Q1A and Q2A, or Q1B and Q2B) to form a current path between the first voltage V1 and the second voltage V2. Power is supplied from the first voltage V1 to the second voltage V2 through the corresponding flying capacitor, and the flying capacitor is charged simultaneously. In the second switching phase PH2A or PH2B, the corresponding flying capacitor is turned on through the third and fourth switches (Q3A and Q4A, or Q3B and Q4B) and connected in parallel with the second voltage V2, supplying power to the second voltage V2 with the stored charge.

[0048] On the other hand, regarding the overall multiphase switching capacitor converter, the multiphase switching capacitor converter 200 periodically switches between a first system state SSys1, an overlapping system state SOLp, and a second system state SSys2 to perform power conversion between a first voltage V1 and a second voltage V2. In the first system state SSys1, the first sub-converter 210A is in its first switching phase PH1A, and the second sub-converter 210B is in its second switching phase PH2B. In the second system state SSys2, the first sub-converter 210A is in its second switching phase PH2A, and the second sub-converter 210B is in its first switching phase PH1B.

[0049] According to the present invention, when the multiphase switching capacitor converter 200 switches from the first system state SSys1 to the second system state SSys2, or from the second system state SSys2 to the first system state SSys1, it first passes through an overlapping system state S0lp, thereby ensuring the continuity of the first current I1 and avoiding voltage surges. In the overlapping system state S0lp, both the first sub-converter 210A and the second sub-converter 210B are in the first switching phases PH1A and PH1B.

[0050] The following uses Figures 4 and 5A-5C to explain in detail the waveforms and circuit electrical connection states related to the switching phase and system state switching.

[0051] The first system state SSys1: During the period from t1 to t2 as shown in Figure 4, the switching state corresponds to that shown in Figure 5B. At this time, the first sub-converter 210A is in its first switching phase PH1A, and the second sub-converter 210B is in its second switching phase PH2B. In this state, the flying capacitor CFA of the first sub-converter 210A is electrically connected between the first voltage V1 and the second voltage V2 after being turned on by the first and second switches (e.g., Q1A and Q2A). Thus, the first voltage V1 supplies power to the second voltage V2 through the flying capacitor CFA, and CFA is charged by V1. At the same time, the flying capacitor CFB of the second sub-converter 210B is turned on by the third and fourth switches (Q3B and Q4B) and connected in parallel with the second voltage V2. The charge stored in the flying capacitor CFB supplies power to the second voltage terminal. It should be noted that the switches controlled to be off in the corresponding states are shown in gray in the figure, and the same applies below.

[0052] Next, the system enters the overlapped system state SOLp: as shown in Figure 4 from t2 to t3 (t4 to t5 are the same), and the corresponding switching states are shown in Figure 5A. In the overlapped system state SOLp, both the first sub-converter 210A and the second sub-converter 210B are in their corresponding first switching phases PH1A and PH1B. At this time, CFA and CFB are electrically connected between the first voltage V1 and the second voltage V2 after being turned on by their corresponding first and second switches (i.e., Q1A and Q2A, and Q1B and Q2B), forming a dual current path. The first voltage V1 supplies power to the second voltage V2 through CFA and CFB, effectively maintaining the continuity of the first current I1 and suppressing the generation of voltage spikes.

[0053] Then it switches to the second system state SSys2: as shown in Figure 4 from t3 to t4, the switching states are as shown in Figure 5C. At this time, the first sub-converter 210A is in its second switching phase PH2A, and the second sub-converter 210B is in its first switching phase PH1B. The specific electrical connection relationship is the opposite of that in the first system state.

[0054] Since switching between the first system state SSys1 and the second system state SSys2 requires passing through the overlapping system state SOLp (t0~t1, t2~t3, t4~t5), it can be ensured that at any given time, the first voltage V1 is electrically connected to at least one flying capacitor and has a current path, thus further ensuring the continuity of the first current I1 and avoiding voltage surges caused by the equivalent inductance Ls. In one embodiment, the duration of the overlapping system state SOLp may, for example, be less than 25% of the switching period Tsw of the multiphase switching capacitor converter.

[0055] Figures 6A and 6B illustrate simulated waveforms, explaining the impact of the multiphase switching capacitor converter 200 on the input and output currents under different control modes. In the conventional non-overlapping control mode (Figure 6A), when the first sub-converter 210A and the second sub-converter 210B perform system-level phase switching (e.g., from the first system state SSys1 to the second system state SSys2), there will be a lag time. During this lag time, neither of them is in the first switching phase, causing the first current I1 (input current) and the second current I2 (input current) to be interrupted (i.e., return to 0). As a result, a voltage spike is generated due to the effect of the equivalent inductance Ls. This high voltage surge may damage the switching elements.

[0056] In contrast, when using the control method of this invention (Figure 6B), an overlapping system state SOLp is inserted between the first system state SSys1 and the second system state SSys2, so that the first sub-converter 210A and the second sub-converter 210B are respectively in the corresponding first switching phases PH1A and PH1B during this time interval. The flying capacitors CFA and CFB are simultaneously electrically connected between the first voltage V1 and the second voltage V2, forming a dual power supply path in parallel, supplying power from the first voltage V1 to the second voltage V2, ensuring that the first current I1 and the second current I2 are not interrupted (i.e., do not return to 0). The simulated waveform shows that under this control mechanism, the first current I1 and the second current I2 are not interrupted, thus avoiding the generation of high-frequency voltage spikes, thereby improving the overall electromagnetic compatibility, extending the operating life of the converter components, or reducing costs.

[0057] Figure 7 shows the control signal waveform of the multiphase switching capacitor converter 200 during a switching cycle in one embodiment of the present invention, illustrating the relationship between the phase switching sequence of its first sub-converter 210A and the second sub-converter 210B and the corresponding system state, and further illustrating the operation of the conduction sequence and zero voltage switching and zero current switching.

[0058] In the operating cycle shown in Figure 7, the first switching phase PH1A of the first sub-converter 210A corresponds to the period from t0 to t8, and its second switching phase PH2A corresponds to the period from t9 to t11. During PH1A, the first sub-converter first pulls the control signal S2A high at t0 to turn on the switch Q2A. Then, when the voltage across switch Q1A (V1 - VCFA - V2) approaches zero, the control signal S1A turns on switch Q1A at t1, making Q1A conduct under ZVS conditions, where VCFA is the voltage across the flying capacitor CFA. The flying capacitor CFA is electrically connected between the first voltage V1 and the second voltage V2 during the period from t1 to t8 for power transfer and charging. t8 to t9 is the dead-time between PH1A and PH2A, used to prevent short-circuit current caused by short-circuit conduction between low-impedance power supplies. Following t9 in the second switching phase PH2A, control signal S4A first turns on switch Q4A, and at t10, because the voltage across switch Q3A VCFA – V2 = 0, switch Q3A turns on under ZVS conditions, completing the operation of the second switching phase PH2A. During the second switching phase PH2A, the flying capacitor CFA is connected in parallel with the second voltage V2, supplying power to the second voltage terminal. t11 to t12 is also the idle time between switching phases.

[0059] The second switching phase PH2B of the second sub-converter 210B is from t3 to t5, and the first switching phase PH1B is from t6 to t14. After PH2B ends, there is a lag time from t5 to t6. At t6 in the first switching phase PH1B, the control signal S2B first turns on the switch Q2B, and at t7, under the condition that the voltage across switch Q1B (Vin - VCFB - Vout) = 0, the switch Q1B is then turned on by the control signal S1B, achieving ZVS conduction. The flying capacitor CFB is electrically connected between V1 and V2 during t7 to t14 for power transfer and charging. Similarly, at the beginning of the second switching phase PH2B, the switch Q4B turns on first at t3, and then Q3B achieves ZVS conduction at t4, completing the operation of the second switching phase PH2B in which the flying capacitor CFB is electrically connected in parallel with the second voltage V2.

[0060] In one embodiment of the present invention, the delay times mentioned in the aforementioned switching phase conduction sequences (e.g., t0 to t1, t9 to t10, t6 to t7, and t3 to t4) can be a preset fixed delay time. This fixed delay time can be designed according to circuit parameters to ensure that after the delay time, the voltage across the switch to be turned on (e.g., Q1A or Q3A) has dropped to or is close to zero, thus facilitating zero-voltage switching. In another embodiment, the delay time can be dynamically adjusted by the controller based on actual measurement results. For example, by detecting whether the voltage across the switch (e.g., Q1A or Q3B) has fallen below a predetermined threshold, the controller can then control the switch to turn on, thereby further improving efficiency.

[0061] In one embodiment, the selection of the aforementioned switching sequence can be based on the voltage levels across the flying capacitor in steady state. In one embodiment, the end of the flying capacitor with the lower steady-state voltage can be switched on to the corresponding electrical connection state first, and after the aforementioned delay time, the other end can be switched on to the corresponding electrical connection state in a zero-voltage switching state.

[0062] At the system level of the multiphase switching capacitor converter, as shown in Figure 7, the operation includes several system state switching as described above. The first system state SSys1 occurs between t2 and t6, where the first sub-converter 210A is in its first switching phase PH1A, and the second sub-converter 210B is in its second switching phase PH2B. The second system state SSys2 occurs between t8 and t12, where the first sub-converter 210A is in its second switching phase PH2A, and the second sub-converter 210B is in its first switching phase PH1B. The overlapping system state SOLp occurs between t0 and t2, t6 and t8, and t12 and t14. During the overlapping system state SOLp, both sub-converters are in their respective first switching phases (PH1A and PH1B). In the overlapping system state SOLp, the flying capacitors CFA and CFB are connected in parallel between V1 and V2, thereby maintaining current continuity and suppressing voltage spikes between the switching of the first system state SSys1 and the second system state SSys2.

[0063] It is worth noting that the waveform shown in Figure 7 also reveals that although the multiphase switching capacitor converter 200 has no obvious idle time at the system level (i.e., the alternating switching of the first sub-converter 210A and the second sub-converter 210B), idle time is still set when the individual switching phases of each sub-converter are switched (such as t8 to t9, t11 to t12, t2 to t3 and t5 to t6). During these idle times, all switches in all sub-converters are turned off to avoid the occurrence of short-circuit current.

[0064] In this embodiment, the first switches Q1A and Q1B, and the third switches Q3A and Q3B, are all turned on only when the voltage across them drops to zero, thus achieving zero-voltage switching. On the other hand, the second switches Q2A and Q2B, and the fourth switches Q4A and Q4B are turned on when the current approaches zero, achieving zero-current switching, thereby effectively reducing switching losses.

[0065] Figure 8 shows a circuit configuration of a multiphase switching capacitor converter 200 in a 4:1 series-parallel architecture according to one embodiment of the present invention. The multiphase switching capacitor converter 800 includes a first sub-converter 810A and a second sub-converter 810B, connected in parallel between a first voltage V1 and a second voltage V2. Each of the first sub-converter 810A and the second sub-converter 810B corresponds to a 4:1 series-parallel switching capacitor converter, each including three flying capacitors (C1A~C3A, C1B~C3B) and multiple switches. The multiple flying capacitors switch between series and parallel connections to achieve a 4:1 voltage conversion.

[0066] Figure 9 shows the circuit configuration of the multiphase switching capacitor converter 900 in a 4:1 pipeline architecture according to another embodiment of the present invention. The multiphase switching capacitor converter 900 in this pipeline architecture also includes a first sub-converter 910A and a second sub-converter 910B, which are connected in parallel between the first voltage V1 and the second voltage V2, and each includes three flying capacitors (C1A~C3A, C1B~C3B) and multiple switches to achieve a 4:1 voltage conversion through stepped voltage distribution.

[0067] Figure 10 shows the circuit configuration of the multiphase switching capacitor converter 1000 in a 4:1 Dickson architecture according to another embodiment of the present invention. This Dickson architecture multiphase switching capacitor converter 1000 also includes a first sub-converter 1010A and a second sub-converter 1010B, connected in parallel between a first voltage V1 and a second voltage V2. Each sub-converter includes three flying capacitors (C1A~C3A, C1B~C3B) and multiple switches, achieving a 4:1 voltage conversion through a stepped voltage distribution.

[0068] Similar to the aforementioned embodiments, in Figures 8 to 10, the switch control signal Ssw controls the first sub-converter and the second sub-converter to switch between corresponding first switching phases (PH1A, PH1B) and second switching phases (PH2A, PH2B) to achieve different flying capacitor electrical connection methods. In the corresponding first switching phase, at least one flying capacitor is electrically connected to the first voltage V1 to form a current path.

[0069] Furthermore, regarding the overall multiphase switching capacitor converter system, the switching control signal Ssw controls the multiphase switching capacitor converter in Figures 8-10 to periodically switch between the first system state SSys1 and the second system state SSys2 through the overlapping system state SOLp to perform power conversion between the first voltage V1 and the second voltage V2. This also maintains the continuity of the first current I1, effectively reduces the ripple and spikes of the first voltage V1 and / or the second voltage V2, improves reliability, suppresses electromagnetic interference, and extends component life.

[0070] Furthermore, similar to the aforementioned embodiments, by following an appropriate switching sequence in each switching phase and through preset or detection delays, zero-voltage switching and zero-current switching can be achieved in each switching phase, thereby reducing switching losses.

[0071] In a single sub-converter that has multiple flying capacitors (such as the first or second sub-converter in the embodiments of Figures 8-10 above), the "terminal phase voltage difference" of the multiple flying capacitors can be used to determine which flying capacitor is prioritized as the critical flying capacitor and to adopt a zero-voltage switching strategy. This invention first defines the "terminal phase voltage difference" as the absolute value of the difference between the voltage levels of the corresponding nodes at a certain end of any flying capacitor in the first and second switching phases. The "terminal phase voltage difference" can serve as the basis for selecting the critical flying capacitor and its corresponding switch. That is, since a larger terminal phase voltage difference will result in higher instantaneous current and losses if directly turned on at the moment of switching, a larger terminal phase voltage difference should be prioritized for a zero-voltage switching conduction strategy.

[0072] Furthermore, if multiple flying capacitors have similar terminal phase voltage differences, the absolute values ​​of their terminal potentials can be compared to determine the conduction sequence and ensure that the voltage across the terminals decreases gradually from high to low, effectively promoting zero-voltage switching. In one embodiment, the flying capacitor can first conduct its lower voltage terminal to form an electrical connection between opposing nodes, allowing the voltage across the higher voltage terminal to decrease naturally through the flying capacitor. Then, the higher voltage terminal is switched on at an appropriate time to achieve zero-voltage switching. Other flying capacitors conduct sequentially from low to high according to the voltage distribution, forming a stepped voltage transfer, further reducing the overall surge current and electromagnetic interference of the system.

[0073] When each sub-converter needs to switch to a different electrical connection relationship between the first and second switching phases (e.g., from series to parallel), this invention suggests that at the beginning of the new switching phase, the terminal with the lowest potential in the original series connection structure should be turned on first, and the voltage should be gradually released so that the high-voltage terminal is turned on last, thereby completing a smooth power conversion. From one perspective, this sequence, for the gradual disassembly of a series connection (e.g., disassembling to parallel), in terms of the capacitor terminal voltage, has the opposite turn-on sequence to that when establishing a series connection. This ensures that the turn-on of each switch is accompanied by a voltage reduction process, aiming to enable the most switches to achieve zero-voltage switching.

[0074] Furthermore, in situations involving load current fluctuations, this invention also incorporates the voltage shift caused by these fluctuations into the control strategy. Even if the voltage difference between each endpoint is predicted under steady-state conditions, actual voltage variations may occur due to load influences during practical operation, affecting the turn-on timing. Therefore, the "endpoint phase voltage difference" defined in this invention, in addition to static analysis, can also be dynamically evaluated and adjusted in the controller through real-time measurement or prediction, enabling critical switches to maintain better zero-voltage switching conduction even under non-steady-state conditions.

[0075] As can be seen from the above embodiments and illustrations, the multiphase switching capacitor converter of this invention introduces a periodic switching mechanism of "overlapping system states" when the first converter and the second converter alternately switch between the "first system state" and the "second system state". This ensures that at least one flying capacitor maintains a current path with the input voltage during system switching, effectively avoiding voltage surges caused by input current interruption. Furthermore, this invention employs a sequential conduction control strategy in the first and second switching phases of each sub-converter, enabling the key switches to conduct during the gradual decrease of the voltage across the circuit, achieving zero-voltage switching and zero-current switching operations, effectively reducing switching losses and switching stress. Therefore, this invention can simultaneously improve conversion efficiency, suppress electromagnetic interference, and improve the stability and reliability of the overall power conversion system.

[0076] The present invention has been described above with reference to preferred embodiments. However, the above description is only intended to facilitate understanding of the invention by those skilled in the art and is not intended to limit the broadest scope of the invention. The described embodiments are not limited to individual application and can also be combined. For example, two or more embodiments can be used in combination, and a component of one embodiment can replace a corresponding component in another embodiment. Furthermore, within the same spirit of the invention, those skilled in the art can conceive of various equivalent changes and combinations. For example, the phrase "processing or calculating based on a signal or generating an output result" in the present invention 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, within the same spirit of the 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.

[0077] 200: Multiphase switching capacitor converter 220: Controller 800: Multiphase switching capacitor converter (4:1 series-parallel architecture) 900: Multiphase switching capacitor converter (4:1 pipeline architecture) 1000: Multiphase switching capacitor converter (4:1 Dickson architecture) Letters / Letter-Number Symbols 210A, 210B: First and second sub-converters 221A, 221B: Delay units 222A, 222B: OR gate 223A, 223B: Inverters 810A, 810B: Serial-to-Parallel Architecture Sub-Converters 910A, 910B: Pipeline architecture sub-converters 1010A, 1010B: Dickson architecture sub-converters C1A~C3A, C1B~C3B: Flying capacitors (4:1 structure) CFA, CFB: Flying Capacitor (2:1 architecture) Clock: time signal I1: First current I2: Second current Ls: Equivalent inductance PH1A, PH1B, PH2A, PH2B: Phase switching Q1A~Q10A, Q1B~Q10B: Switches S1A~S10A, S1B~S10B: Switch control signals Sckb: Inverting clock signal Sd1, Sd2: Delayed clock signals SOlp: State of the overlapping system SSys1, SSys2: First and second system states Ssw: Switch control signal t0~t14: Time points Tsw: Switching cycle V1: First voltage V2: Second voltage VCFA, VCFB: Transverse voltage of flying capacitor

Claims

1. A multiphase switching capacitor converter for converting a first voltage to a second voltage, or vice versa, the multiphase switching capacitor converter comprising: a first sub-converter and a second sub-converter, coupled in parallel between the first voltage and the second voltage; wherein each of the first sub-converter and the second sub-converter includes: A fast capacitor; The system includes multiple switches for periodically switching the electrical connection between the flying capacitor and the first voltage and the second voltage between a first switching phase and a second switching phase. In the first switching phase, the flying capacitor is electrically connected between the first voltage and the second voltage through the switching of the multiple switches to form a current path. The first voltage charges the flying capacitor and supplies power to the second voltage. In the second switching phase, the flying capacitor is electrically disconnected from the first voltage and electrically connected to the second voltage through the switching of the multiple switches, and the flying capacitor discharges to supply power to the second voltage. The multiphase switching capacitor converter periodically switches between a first system state and a second system state to perform power conversion between the first voltage and the second voltage. In the first system state, the first sub-converter is in the first switching phase, and the second sub-converter is in the second switching phase. In the second system state, the first sub-converter is in the second switching phase, and the second sub-converter is in the first switching phase. When switching from the first system state to the second system state, or vice versa, an overlapping system state is first passed through to maintain the continuity of the first current corresponding to the first voltage and avoid a voltage surge. In the overlapping system state, the first sub-converter and the second sub-converter are simultaneously in the first switching phase. When each of the first and second sub-converters enters the first or second switching phase, the first terminal of the flying capacitor is turned on before the second terminal to connect to the node corresponding to the first switching phase, forming the coupling relationship required for the first switching phase. This allows the second terminal to gradually approach a zero-voltage state and then be turned on to connect to the node corresponding to the first switching phase, thereby achieving zero-voltage switching. In steady state, the terminal of the flying capacitor with the lower voltage corresponds to the first terminal; and / or the terminal phase voltage difference of the flying capacitor corresponds to the first terminal, where the terminal phase voltage difference refers to the absolute value of the difference between the voltage levels of each terminal of the flying capacitor in the first switching phase and the second switching phase.

2. The multiphase switching capacitor converter as claimed in claim 1, wherein the duration of the overlapping system state is less than 25% of the switching cycle of one of the multiphase switching capacitor converters.

3. The multiphase switching capacitor converter as described in claim 1, wherein each of the first sub-converter and the second sub-converter undergoes a lag time before switching from the first switching phase to the second switching phase, or from the second switching phase to the first switching phase.

4. The multiphase switching capacitor converter as claimed in claim 1, wherein each of the first sub-converter and the second sub-converter includes a plurality of flying capacitors, wherein: In the first switching phase, the plurality of flying capacitors sequentially complete the corresponding electrical connections, such that the voltage changes at the first and second terminals of each flying capacitor gradually increase; and / or in the second switching phase, the plurality of flying capacitors sequentially complete the corresponding electrical connections, such that the voltage changes at the first and second terminals of each flying capacitor gradually decrease.

5. The multiphase switching capacitor converter as claimed in claim 1, wherein, upon entering the first switching phase or the second switching phase, the first terminal of the flying capacitor is switched to zero current to electrically connect to the corresponding node.

6. The multiphase switching capacitor converter as described in claim 4, wherein the plurality of switches includes first to fourth switches, and wherein: The first switch is coupled between the first voltage and the second terminal of the flying capacitor; the second switch is coupled between the first terminal of the flying capacitor and the second voltage; the third switch is coupled between the second terminal of the flying capacitor and the second voltage; and the fourth switch is coupled between the first terminal of the flying capacitor and a ground potential; wherein in the first switching phase, the first switch and the second switch are turned on, electrically connecting the flying capacitor between the first voltage and the second voltage, wherein the first voltage charges the flying capacitor and supplies power to the second voltage; wherein in the second switching phase, the third switch and the fourth switch are turned on, electrically connecting the flying capacitor in parallel with the second voltage, wherein the flying capacitor discharges to supply power to the second voltage.

7. The multiphase switching capacitor converter as described in claim 6, wherein the first switch turns on after the second switch turns on, after a preset delay time, to achieve zero voltage switching, and / or the third switch turns on after the fourth switch turns on, after a preset delay time, to achieve zero voltage switching; or wherein after the second switch turns on, the first switch turns on when the voltage across it is lower than a threshold, to achieve zero voltage switching, and / or after the fourth switch turns on, the third switch turns on when the voltage across it is lower than a threshold, to achieve zero voltage switching.

8. The multiphase switching capacitor converter as claimed in claim 6, wherein the voltage conversion ratio between the first voltage and the second voltage is 2:

1.

9. The multiphase switching capacitor converter as claimed in claim 1, wherein the voltage conversion ratio between the first voltage and the second voltage is K:1, wherein each of the first sub-converter and the second sub-converter is a series-parallel switching capacitor converter and each has a complex number of flying capacitors, wherein K is a positive integer greater than or equal to 3.

10. The multiphase switching capacitor converter as claimed in claim 1, wherein the voltage conversion ratio between the first voltage and the second voltage is K:1, wherein each of the first sub-converter and the second sub-converter corresponds to a pipeline switching capacitor converter or a Dickson switching capacitor converter, wherein K is a positive integer greater than or equal to 4.

11. The multiphase switching capacitor converter as claimed in claim 1, wherein the multiphase switching capacitor converter includes an equivalent inductance between the first voltage and the flying capacitor, wherein the equivalent inductance causes the voltage surge in the event of an interruption of the first current.

12. A control method for performing power conversion between a first voltage and a second voltage, comprising: controlling each of two sets of sub-conversion units to periodically switch between a first switching phase and a second switching phase, wherein during the first switching phase, a flying capacitor is electrically connected between the first voltage and the second voltage to form a current path, wherein the first voltage charges the flying capacitor and supplies power to the second voltage, and during the second switching phase, the flying capacitor is disconnected from the first voltage and electrically connected to the second voltage, wherein the flying capacitor discharges to supply power to the second voltage; The two sets of sub-conversion units are controlled to periodically switch between a first system state and a second system state, wherein the first system state corresponds to one sub-conversion unit of the two sets of sub-conversion units being in its corresponding first switching phase, and the other sub-conversion unit being in its corresponding second switching phase, wherein the second system state is out of phase with the first system state; and an overlapping system state is used between the first system state and the second system state to ensure that the two sets of sub-conversion units are simultaneously in their corresponding first switching phase, so as to maintain the continuity of a first current corresponding to the first voltage and avoid a voltage surge; wherein the step of controlling each sub-conversion unit to periodically switch between the first switching phase and the second switching phase includes: When each of the sub-conversion units enters the first switching phase, the electrical connection between the first terminal of the flying capacitor and the corresponding node is turned on first, and the electrical connection between the second terminal and the corresponding node is turned on with a delay, thereby turning on the second terminal under conditions that gradually approach zero voltage, so as to achieve zero voltage switching; wherein in steady state, the terminal of the flying capacitor with the lower voltage corresponds to the first terminal; and / or the terminal phase voltage difference of the flying capacitor corresponds to the first terminal, wherein the terminal phase voltage difference refers to the absolute value of the difference between the voltage levels of each terminal of the flying capacitor in the first switching phase and the second switching phase.

13. The control method as described in claim 12, wherein the duration of the overlapping system state is less than 25% of a switching cycle.

14. The control method as described in claim 12, wherein the step of controlling each of the sub-conversion units to periodically switch between the first switching phase and the second switching phase includes: Each sub-conversion unit first experiences a delay time between the corresponding first switching phase and the second switching phase to avoid short-circuit current between the switching elements of each sub-conversion unit.

15. The control method as claimed in claim 12, wherein each of the sub-conversion units includes a complex number of flying capacitors, and the step of controlling each of the sub-conversion units to periodically switch between the first switching phase and the second switching phase further includes: In the first switching phase, the electrical connections of the corresponding nodes of the complex flying capacitors are sequentially made, so that the voltage changes of the corresponding first terminal and the second terminal gradually increase; and in the second switching phase, the electrical connections of the corresponding nodes of the complex flying capacitors are sequentially made, so that the voltage changes of the corresponding first terminal and the second terminal gradually decrease.

16. The control method as described in claim 12, wherein the conduction of the first terminal of each of the plurality of flying capacitors is a zero-current switching to electrically connect to the corresponding node.

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