Multi-phase switched capacitor converter and control method

Abstract

A multi-phase switched capacitor converter and control method are disclosed. The multi-phase switched capacitor converter is used to convert a first voltage to a second voltage or vice versa. The converter includes two groups of sub-converters connected in parallel between the input and output voltages. Each sub-converter includes a flying capacitor and a plurality of switches. Power conversion is performed between first and second switching phases by periodically switching electrical connections between the flying capacitor and voltage sources. The two groups of sub-converters are periodically switched between first and second system states and an overlap system state is introduced during the transition between the first and second system states to ensure that both sub-converters are in the first switching phase at the same time, thereby ensuring that current is not interrupted to reduce voltage spikes.

Description

Technical Field

[0001] This invention relates to switching power conversion technology, and in particular to a multiphase switching capacitor converter and its control method. Background Technology

[0002] Power converters are widely used in various applications, including mobile devices. As devices face increasingly stringent limitations in size and temperature, the design requirements for high efficiency and high power density in power converters have become 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 two-phase operating voltage multiplier switching capacitor converter using two sets of flying capacitors and eight switches. Figure 1 As shown. This technology uses a non-overlapping clock for control, and although it can achieve multi-phase power conversion, there is still room for improvement in terms of efficiency, surge and electromagnetic interference suppression.

[0004] To overcome the limitations of the prior art, this application proposes a multiphase switching capacitor converter that uses a controller to interleave the operating phases of multiple converters and introduces 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 a first system state and a 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, thereby maintaining the continuity of a first current corresponding to the first voltage and avoiding surges. In this 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 all switching cycles of the multiphase switching capacitor converter.

[0007] In a preferred embodiment, each of the first sub-converter and the second sub-converter undergoes a delay time before switching from the first switching phase to the second switching phase or from the second switching phase to the first switching phase, thereby preventing short-circuit current from occurring 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. Thus, 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 change at the first and second terminals of each flying capacitor is gradually increasing; and / or in a second switching phase, the plurality of flying capacitors sequentially complete corresponding electrical connections, such that the voltage change at the first and second terminals of each flying capacitor is gradually decreasing.

[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 include first to fourth switches, 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 each has multiple 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 system state; and, between the first system state and the second system state, by means of an overlapping system state, causing the two sets of sub-conversion units to be simultaneously in their corresponding first switching phase, so as to maintain the continuity of a first current corresponding to the first voltage and avoid 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 plurality 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 plurality of flying capacitors so that the voltage changes of the corresponding first terminal and second terminal gradually increase; and in the second switching phase, sequentially connecting the electrical connections of the corresponding nodes of the plurality of 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 the present invention. Attached Figure Description

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

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

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

[0025] Figure 4 Show corresponding Figure 2 The control signal waveform diagram.

[0026] Figure 5A Show corresponding Figure 2 A schematic diagram of the switching states of the overlapping system.

[0027] Figure 5B Show corresponding Figure 2 A schematic diagram of the switching state of the first system state.

[0028] Figure 5C Show corresponding Figure 2 A schematic diagram of the switching state of the second system state.

[0029] Figure 6A This displays the input and output current waveforms when using the non-overlapping control method in the prior art.

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

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

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

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

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

[0035] Explanation of symbols in the diagram

[0036] 200: Multiphase switching capacitor converter

[0037] 220: Controller

[0038] 800: Multiphase switching capacitor converter (4:1 series-parallel architecture)

[0039] 900: Multiphase switching capacitor converter (4:1 pipeline architecture)

[0040] 1000: Multiphase switching capacitor converter (4:1 Dickson architecture)

[0041] Letters / Letter-Number Symbols

[0042] 210A, 210B: First and second sub-converters

[0043] 221A, 221B: Delay units

[0044] 222A, 222B: OR gates

[0045] 223A, 223B: Inverters

[0046] 810A, 810B: Serial-to-Parallel Architecture Sub-Converters

[0047] 910A, 910B: Pipeline architecture sub-converters

[0048] 1010A, 1010B: Dickson architecture sub-converters

[0049] C1A~C3A, C1B~C3B: Flying capacitors (4:1 structure)

[0050] CFA, CFB: Flying Capacitors (2:1 Architecture)

[0051] Clock: Clock signal

[0052] I1: First current

[0053] I2: Second current

[0054] Ls: Equivalent inductance

[0055] PH1A, PH1B, PH2A, PH2B: Phase switching

[0056] Q1A~Q10A, Q1B~Q10B: Switches

[0057] S1A~S10A, S1B~S10B: Switch control signals

[0058] Sckb: Inverting clock signal

[0059] Sd1, Sd2: Delayed clock signals

[0060] SOlp: State of the overlapping system

[0061] SSys1, SSys2: First and second system states

[0062] Ssw: Switch control signal

[0063] t0~t14: Time points

[0064] Tsw: Switching cycle

[0065] V1: First voltage

[0066] V2: Second voltage

[0067] VCFA, VCFB: Transverse voltage of flying capacitor Detailed Implementation

[0068] The accompanying drawings in this invention are all schematic and are mainly intended to show the coupling relationship between various circuits and the relationship between various signal waveforms. The circuits, signal waveforms and frequencies are not drawn to scale.

[0069] Figure 2 This diagram shows a circuit architecture schematic 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 periodic switching of the switches, forming a 2:1 switching capacitor voltage divider.

[0070] 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 a second switching phase PH2A, periodically switching the electrical connection between its internal flying capacitor and the first voltage V1 and the second voltage V2 via multiple 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.

[0071] like Figure 2 As shown, 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.

[0072] 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).

[0073] 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.

[0074] In one embodiment, before switching to the first system state or the second system state, an overlapping system state is required to form a continuous current path between the input voltage and each sub-converter, ensuring that the first current I1 is not interrupted, effectively suppressing voltage surges, thereby improving the reliability, electromagnetic interference characteristics and service life of the converter, or reducing the electrical requirements of the switching elements, thus reducing costs.

[0075] The specific circuit operation and switching of the aforementioned first and second switching phases will be explained in detail in subsequent paragraphs.

[0076] It should be noted that the embodiments of the multiphase switching capacitor converter in this article are mainly illustrated by 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 power conversion from a second voltage V2 to a first voltage V1.

[0077] Figure 3 This diagram illustrates 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 switch control signal S1A and a third switch control signal S3A for the first sub-converter 210A via 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 switch control signal S1B and a third switch control signal S3B for the second sub-converter 210B via 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 the inverted clock signal Sckb via delay units 221A and 221B, respectively.

[0078] Figure 4 and Figures 5A to 5C This section describes, in one embodiment of the present invention, the operating state of the multiphase switching capacitor converter 200 during a switching cycle and the corresponding circuit switching operation. Figure 4 Displayed corresponding to Figure 2 The waveform diagram of the control signal. Figures 5A to 5C Then it shows the corresponding Figure 2 The switching states of the circuit under different conditions.

[0079] 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.

[0080] 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. The first voltage V1 supplies power to the second voltage V2 through the corresponding flying capacitor, and simultaneously charges the flying capacitor. 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.

[0081] 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.

[0082] 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.

[0083] The following is passed Figure 4 and Figures 5A-5C The waveforms and circuit electrical connection states related to the switching phase and system state switching are described in detail.

[0084] First system state SSYs1: such as Figure 4 During the period from t1 to t2, the switch switching states correspond as follows: Figure 5BAs shown. 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 via 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 via the third and fourth switches (Q3B and Q4B), and is 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.

[0085] Then it enters the overlapping system state SOlp: such as Figure 4 As shown, the switching states of t2 to t3 (and t4 to t5) correspond as follows: Figure 5A As shown. 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.

[0086] Then it switches to the second system state, SSYS2: such as Figure 4 The switching states of t3 to t4 are shown as follows: Figure 5C As shown. 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. Their specific electrical connection relationship is the opposite of that of the first system state.

[0087] 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.

[0088] Figure 6A and Figure 6BThe simulated waveforms illustrate the impact of different control methods on the input and output currents of the multiphase switching capacitor converter 200. In the traditional non-overlapping control method ( Figure 6A When the first sub-converter 210A and the second sub-converter 210B perform system-level phase switching (e.g., switching from the first system state SSys1 to the second system state SSys2), there will be a lag time during which 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. Such a high voltage surge may cause damage to the switching element.

[0089] In contrast, when using the control method of the present 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. 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, 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). Simulation waveforms show that under this control mechanism, the first current I1 and the second current I2 are not interrupted, thus avoiding high-frequency voltage spikes, thereby improving overall electromagnetic compatibility, extending the operating life of the converter components, and potentially reducing costs.

[0090] Figure 7 This invention illustrates the control signal waveform of a multiphase switching capacitor converter 200 during a switching cycle in one embodiment of the invention, explaining the correlation between the phase switching sequence of its first sub-converter 210A and 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.

[0091] At Figure 7In the operating cycle shown, 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 flyaway 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.

[0092] 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 the switch Q1B (Vin - VCFB - Vout) = 0, the switch Q1B is then turned on by the control signal S1B, realizing 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 realizes 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.

[0093] 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.

[0094] 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.

[0095] At the system level of multiphase switching capacitor converters, such as Figure 7 The operation described includes several system state transitions 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. Overlapping system states SOLp occur between t0 and t2, t6 and t8, and t12 and t14. During overlapping system states SOLp, both sub-converters are in their respective first switching phases (PH1A and PH1B). In overlapping system states 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 transitions between the first system state SSys1 and the second system state SSys2.

[0096] It is worth noting that, Figure 7 The waveforms shown also reveal that although the multiphase switching capacitor converter 200 has no significant 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.

[0097] In this embodiment, the first switches Q1A and Q1B, as well as the third switches Q3A and Q3B, only turn on 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 turn on when the current approaches zero, achieving zero-current switching, thereby effectively reducing switching losses.

[0098] Figure 8 The diagram illustrates 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 electrical connections to achieve a 4:1 voltage conversion.

[0099] Figure 9 The diagram shows the circuit configuration of a multiphase switching capacitor converter 900 in a 4:1 pipeline architecture according to another embodiment of the present invention. This pipeline architecture multiphase switching capacitor converter 900 also includes a first sub-converter 910A and a second sub-converter 910B, 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.

[0100] Figure 10 The diagram shows a circuit configuration of a 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.

[0101] Similar to the aforementioned embodiments, Figures 8-10 In the process, the switch control signal Ssw controls the first sub-converter and the second sub-converter to switch between the corresponding first switching phase (PH1A, PH1B) and the second switching phase (PH2A, PH2B) to realize 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.

[0102] Furthermore, regarding the overall multiphase switching capacitor converter system, the switching control signal Ssw controls... Figures 8-10 The multiphase switching capacitor converter periodically switches 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.

[0103] Furthermore, similar to the aforementioned embodiments, by using a preset or detection-based delay in each switching phase according to an appropriate switching sequence, zero-voltage switching and zero-current switching can be achieved in each switching phase, thereby reducing switching losses.

[0104] In a single sub-converter, i.e., a converter with multiple flying capacitors (as mentioned above) Figures 8-10 In the embodiments of the first or second sub-converter, the selection of the critical flying capacitor can be further determined based on the "endpoint phase voltage difference" of multiple flying capacitors, prioritizing the zero-voltage switching strategy. This invention first defines the "endpoint phase voltage difference" as the absolute value of the difference in voltage levels between the corresponding nodes at a certain end of any flying capacitor in the first and second switching phases. The "endpoint phase voltage difference" can serve as the basis for selecting the critical flying capacitor and its corresponding switch. That is, since a larger endpoint phase voltage difference would result in higher instantaneous current and losses if directly switched on at the moment of switching, a larger endpoint phase voltage difference should be prioritized for the zero-voltage switching conduction strategy.

[0105] 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 capacitor 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 opposite nodes, allowing the voltage across the higher voltage terminal to decrease naturally through the flying capacitor. Then, at an appropriate time, the switch at the higher voltage terminal is turned on 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.

[0106] 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 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, thereby facilitating zero-voltage switching for the most switches.

[0107] 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.

[0108] As can be seen from the above embodiments and illustrations, the multiphase switching capacitor converter of this application 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 application further employs a sequential conduction control strategy in the first and second switching phases of each sub-converter, enabling 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.

[0109] 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 used in combination. For example, two or more embodiments can be used in combination, and some components of one embodiment can be used to replace corresponding components 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 ways to combine them, which will not be listed here. Therefore, the scope of the present invention should cover the above and all other equivalent changes.

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 are coupled between the first voltage and the second voltage; Each of the first sub-converter and the second sub-converter includes: A fast capacitor; as well as Multiple switches are used to periodically switch 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 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 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 from the second system state to the first system state, an overlapping system state is first passed through, thereby maintaining the continuity of the first current corresponding to the first voltage and avoiding surges. In the overlapping system state, the first sub-converter and the second sub-converter are simultaneously in the first switching phase.

2. The multiphase switching capacitor converter as described in claim 1, wherein, The duration of this overlapping system state is less than 25% of all switching cycles of the multiphase switching capacitor converter.

3. The multiphase switching capacitor converter as described in claim 1, wherein, When each of the first sub-converter and the second sub-converter switches from the first switching phase to the second switching phase, or from the second switching phase to the first switching phase, a delay time is first passed, thereby avoiding short-circuit current between the multiple switches.

4. The multiphase switching capacitor converter as described in claim 1, wherein, 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. Thus, 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. Wherein, in steady state, the end of the flying capacitor with the lower voltage corresponds to the first end; and / or The flying capacitor has a lower terminal phase voltage difference corresponding 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 at the first switching phase and the second switching phase.

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

6. The multiphase switching capacitor converter as described in claim 4, wherein, When entering the first switching phase or the second switching phase, the first terminal of the speeding capacitor switches to zero current to be electrically connected to the corresponding node.

7. The multiphase switching capacitor converter as described in claim 1, wherein, The plurality of switches includes first to fourth switches, wherein: A first switch is coupled between the first voltage and the second terminal of the flying capacitor; A second switch is coupled between the first terminal of the flying capacitor and the second voltage; A third switch is coupled between the second terminal of the flying capacitor and the second voltage; and A fourth switch is coupled between the first terminal of the flying capacitor and the ground potential; In the first switching phase, the first and second switches are turned on, and the flying capacitor is electrically connected between the first voltage and the second voltage, wherein the first voltage charges the flying capacitor and supplies power to the second voltage; In the second switching phase, the third and fourth switches are turned on, and the flying capacitor is connected in parallel with the second voltage. The flying capacitor discharges to supply power to the second voltage.

8. The multiphase switching capacitor converter as described in claim 7, wherein, The first switch conducts only after a preset delay time following the conduction of the second switch, to achieve zero-voltage switching; and / or, the third switch conducts only after a preset delay time following the conduction of the fourth switch, to achieve zero-voltage switching; or Wherein, after the second switch is turned on, the first switch is turned on when the voltage across its terminals is lower than a threshold, so as to achieve zero voltage switching, and / or, after the fourth switch is turned on, the third switch is turned on when the voltage across its terminals is lower than a threshold, so as to achieve zero voltage switching.

9. The multiphase switching capacitor converter as described in claim 7, wherein, The voltage conversion ratio between the first voltage and the second voltage is 2:

1.

10. The multiphase switching capacitor converter as described 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 multiple flying capacitors, wherein K is a positive integer greater than or equal to 3.

11. The multiphase switching capacitor converter as described 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-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.

12. The multiphase switching capacitor converter as described 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 a voltage surge in the event of an interruption of the first current.

13. A control method for switching power supplies between a first voltage and a second voltage, comprising: Each of the two sets of sub-conversion units is controlled 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 a first voltage to form a current path to a second voltage, and during the second switching phase, the flying capacitor is disconnected from the first 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 By using an overlapping system state between the first system state and the second system state, the two sets of sub-conversion units are simultaneously in their corresponding first switching phases, so as to maintain the continuity of the first current corresponding to the first voltage and avoid surges.

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

15. The control method as described in claim 13, wherein, The steps of controlling each sub-conversion unit to periodically switch between the first switching phase and the second switching phase include: 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.

16. The control method as described in claim 13, wherein, The steps of controlling each sub-conversion unit to periodically switch between the first switching phase and the second switching phase include: When each of the sub-conversion units enters the first switching phase, the first terminal of the flying capacitor is preferentially connected to the electrical connection of the corresponding node, and the second terminal is delayed in being connected to the electrical connection of the corresponding node, thereby enabling the second terminal to be connected under conditions that gradually approach zero voltage, so as to achieve zero voltage switching. Wherein, in steady state, the end of the flying capacitor with the lower voltage corresponds to the first end; and / or The flying capacitor has a lower terminal phase voltage difference corresponding 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 at the first switching phase and the second switching phase.

17. The control method as described in claim 16, wherein, Each of the sub-conversion units includes multiple flying capacitors, wherein 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: During the first switching phase, the electrical connections of the corresponding nodes of the plurality of speeding 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 multiple speed capacitors are sequentially made so that the voltage changes of the corresponding first terminal and the second terminal gradually decrease.

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

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