A cascaded switched-capacitor converter

Abstract

The application belongs to the technical field of switching power supply, and relates to a cascaded switching capacitor converter. An auxiliary circuit is added between two branches outside a traditional cascaded converter. In a dead time when all main power tubes are closed, the auxiliary circuit can transfer the charge of one branch to another branch, realize zero-voltage turn-on of all main power tubes, and reduce switching loss.

Description

Technical Field

[0001] This application belongs to the field of switching power supply technology, specifically relating to a cascaded switched capacitor converter. Background Technology

[0002] Traditional inductive DC-DC converters, such as buck, boost, and buck-boost converters, are widely used in 5G base stations, server power supplies, and mobile phone motherboards to convert between different voltages. However, due to significant switching and inductance losses, the conversion efficiency of inductive DC-DC converters is typically low. Applications such as high-energy-consuming 5G communication and high-power fast charging for mobile phones demand much higher conversion efficiency from inductive DC-DC converters. Traditional inductive DC-DC converters can no longer meet these efficiency requirements.

[0003] Compared to inductors, capacitors have a higher energy density. Therefore, switched-capacitor converters, which use capacitors for energy transfer, have a much higher conversion efficiency than inductive DC-DC converters and are widely used in various high-efficiency applications. Among the many types of switched-capacitor converter topologies, cascaded switched-capacitor converters are widely used due to their low equivalent impedance.

[0004] like Figure 1 The diagram shows a schematic of a conventional cascaded 4:1 switched capacitor converter. This cascaded 4:1 switched capacitor converter includes 14 power transistors (i.e., power transistors Q1A, Q1B, Q2A, Q2B, Q3A, Q3B, Q4A, Q4B, Q5A, Q5B, Q6A, Q6B, Q7A, and Q7B), four capacitors (i.e., capacitors C1A, C1B, C2A, and C2B), an input capacitor CIN, an output capacitor COUT, and an output load IOUT. In terms of control, power transistors Q1B, Q2A, Q3B, Q4B, Q5A, Q6B, and Q7A are driven by the same control signal, as are power transistors Q1A, Q2B, Q3A, Q4A, Q5B, Q6A, and Q7B. Both control signals are 50% duty cycle square wave signals with complementary waveforms. This cascaded 4:1 switched-capacitor converter can make the output voltage VOUT 1 / 4 of the input voltage, i.e., VIN = 4 * VOUT. The voltages across the four capacitors are VC1A = VOUT, VC1B = VOUT, VC2A = 2 * VOUT, and VC2B = 2 * VOUT, respectively.

[0005] While existing cascaded 4:1 switched-capacitor converters have no turn-off or inductance losses, they still require overcoming the parasitic capacitances Cds and Cgd when the power transistors are turned on, resulting in some turn-on losses. In high-voltage, low-current applications, the voltage difference between Cds and Cgd is even greater, contributing a larger share to the turn-on losses and limiting further improvements in the conversion efficiency of cascaded 4:1 switched-capacitor converters. Summary of the Invention

[0006] This application addresses the aforementioned problems by proposing a switched-capacitor converter. By adding auxiliary circuitry, it achieves zero-voltage switching (ZVS) of all main power transistors, reducing switching losses. Furthermore, this switched-capacitor converter can be expanded to a 2... N 1. Cascaded switched capacitor converter.

[0007] On the one hand, this application provides a cascaded switched capacitor converter, including an auxiliary circuit, a first branch and a second branch. The auxiliary circuit is connected between the first branch and the second branch. The power transistors of the first branch and the second branch are main power transistors. The auxiliary circuit is used to transfer the charge of one branch to another branch during the dead time when all main power transistors are turned off, so that the voltage difference across each main power transistor becomes zero and each main power transistor is turned on at zero voltage.

[0008] In some embodiments, the cascaded switched-capacitor converter is a 4:1 cascaded switched-capacitor converter, wherein the first branch includes a first power transistor, a second power transistor, a third power transistor, a fourth power transistor, a fifth power transistor, a sixth power transistor, a seventh power transistor, a first capacitor, and a second capacitor; and the second branch includes an eighth power transistor, a ninth power transistor, a tenth power transistor, an eleventh power transistor, a twelfth power transistor, a thirteenth power transistor, a fourteenth power transistor, a third capacitor, and a fourth capacitor.

[0009] The first terminals of the seventh and fourteenth power transistors are the input terminals of the cascaded switched capacitor converter, which are connected to the external input voltage. The second terminal of the seventh power transistor is connected to the first terminal of the second capacitor and the first terminal of the sixth power transistor, respectively. The second terminal of the fourteenth power transistor is connected to the first terminal of the fourth capacitor and the first terminal of the thirteenth power transistor, respectively.

[0010] The second terminal of the sixth power transistor is connected to the first terminal of the tenth power transistor, the first terminal of the third capacitor, and the first terminal of the twelfth power transistor, respectively. The second terminal of the thirteenth power transistor is connected to the first terminal of the third power transistor, the first terminal of the first capacitor, and the first terminal of the fifth power transistor, respectively.

[0011] The second terminal of the fifth power transistor is connected to the second terminal of the second capacitor and the first terminal of the fourth power transistor, respectively. The second terminal of the twelfth power transistor is connected to the second terminal of the fourth capacitor and the first terminal of the eleventh power transistor, respectively. The second terminals of the fourth power transistor and the eleventh power transistor are grounded.

[0012] The second terminal of the third power transistor is connected to the first terminal of the second power transistor. The second terminal of the second power transistor is connected to the second terminal of the first capacitor and the first terminal of the first power transistor. The second terminal of the first power transistor is grounded.

[0013] The second terminal of the tenth power transistor is connected to the first terminal of the ninth power transistor. The second terminal of the ninth power transistor is connected to the second terminal of the third capacitor and the first terminal of the eighth power transistor. The second terminal of the eighth power transistor is grounded.

[0014] The connection point between the second terminal of the third power transistor, the first terminal of the second power transistor, the first terminal of the ninth power transistor, and the second terminal of the tenth power transistor is the output terminal of the cascaded switched capacitor converter.

[0015] The connection point of the second terminal of the second capacitor, the second terminal of the fifth power transistor, and the first terminal of the fourth power transistor is the second node of the first branch, and the connection point of the second terminal of the fourth capacitor, the second terminal of the twelfth power transistor, and the first terminal of the eleventh power transistor is the fourth node of the second branch.

[0016] The two ends of the auxiliary circuit are connected to the second node and the fourth node, respectively.

[0017] In some embodiments, the auxiliary circuit includes a fifteenth power transistor, a sixteenth power transistor, a seventeenth power transistor, an eighteenth power transistor, and an inductor; wherein, the first end of the fifteenth power transistor is connected to the second node, the second end of the fifteenth power transistor is connected to the first end of the sixteenth power transistor and the first end of the inductor respectively, and the second end of the sixteenth power transistor is grounded; the second end of the inductor is connected to the first end of the seventeenth power transistor and the first end of the eighteenth power transistor respectively, the second end of the seventeenth power transistor is grounded, and the second end of the eighteenth power transistor is connected to the fourth node.

[0018] In some embodiments, the operating timing of the cascaded switched capacitor converter includes six stages, as described below.

[0019] Phase 1: The second, fifth, seventh, eighth, tenth, eleventh, thirteenth, sixteenth, and eighteenth power transistors are turned on, while the other power transistors are turned off; the first and second capacitors are in a charging state, while the third and fourth capacitors are in a discharging state, and the inductor current is 0.

[0020] Second stage: The fifth, fifteenth, and eighteenth power transistors are turned on, while the other power transistors are turned off; the inductor current rises, and the second stage ends when the inductor current reaches its maximum value.

[0021] Phase 3: The fifteenth and eighteenth power transistors are turned on, while the other power transistors are turned off; the inductor current decreases, and the third phase ends when the inductor current drops to 0.

[0022] Phase 4: The first, third, fourth, sixth, ninth, twelfth, fourteenth, fifteenth, and seventeenth power transistors are turned on, while the other power transistors are turned off; the first and fourth capacitors are in a discharging state, while the second and third capacitors are in a charging state; the inductor current is 0.

[0023] Phase 5: The twelfth, fifteenth, and eighteenth power transistors are turned on, while the other power transistors are turned off; the inductor current rises, and the fifth phase ends when the inductor current reaches its maximum value.

[0024] Phase 6: The 15th and 18th power transistors are turned on, while the other power transistors are turned off; the inductor current decreases, and when the inductor current drops to 0, Phase 6 ends and returns to Phase 1.

[0025] In some embodiments, the fifteenth, sixteenth, seventeenth, and eighteenth power transistors are all N-type power transistors; or, the fifteenth and eighteenth power transistors are P-type, and the sixteenth and seventeenth power transistors are N-type.

[0026] In some embodiments, the cascaded switched-capacitor converter is an 8:1 cascaded switched-capacitor converter. The first branch includes a first power transistor, a second power transistor, a third power transistor, a fourth power transistor, a fifth power transistor, a sixth power transistor, a seventh power transistor, a first sub-power transistor, a third sub-power transistor, a fifth sub-power transistor, a first capacitor, a second capacitor, and a first sub-capacitor. The second branch includes an eighth power transistor, a ninth power transistor, a tenth power transistor, an eleventh power transistor, a twelfth power transistor, a thirteenth power transistor, a fourteenth power transistor, a second sub-power transistor, a fourth sub-power transistor, a sixth sub-power transistor, a third capacitor, a fourth capacitor, and a second sub-capacitor.

[0027] The first terminals of the fifth and sixth sub-power transistors are the input terminals of the cascaded switched capacitor converter, which are connected to the external input voltage. The second terminal of the fifth sub-power transistor is connected to the first terminal of the first sub-capacitor and the first terminal of the third sub-power transistor, respectively. The second terminal of the sixth sub-power transistor is connected to the first terminal of the second sub-capacitor and the first terminal of the fourth sub-power transistor, respectively.

[0028] The second terminal of the third sub-power transistor is connected to the first terminal of the thirteenth power transistor, the first terminal of the fourth capacitor, and the first terminal of the second sub-power transistor, respectively. The second terminal of the fourth sub-power transistor is connected to the first terminal of the sixth power transistor, the first terminal of the second capacitor, and the first terminal of the first sub-power transistor, respectively.

[0029] The second terminal of the sixth power transistor is connected to the first terminal of the tenth power transistor, the first terminal of the third capacitor, and the first terminal of the twelfth power transistor, respectively. The second terminal of the thirteenth power transistor is connected to the first terminal of the third power transistor, the first terminal of the first capacitor, and the first terminal of the fifth power transistor, respectively.

[0030] The second terminal of the third power transistor is connected to the first terminal of the second power transistor. The second terminal of the second power transistor is connected to the second terminal of the first capacitor and the first terminal of the first power transistor. The second terminal of the first power transistor is grounded.

[0031] The second terminal of the fifth power transistor is connected to the second terminal of the second capacitor and the first terminal of the fourth power transistor, respectively, and the second terminal of the fourth power transistor is grounded.

[0032] The second terminal of the first sub-power transistor is connected to the second terminal of the first sub-capacitor and the first terminal of the seventh power transistor, respectively, and the second terminal of the seventh power transistor is grounded.

[0033] The second terminal of the tenth power transistor is connected to the first terminal of the ninth power transistor. The second terminal of the ninth power transistor is connected to the second terminal of the third capacitor and the first terminal of the eighth power transistor. The second terminal of the eighth power transistor is grounded.

[0034] The second terminal of the twelfth power transistor is connected to the second terminal of the fourth capacitor and the first terminal of the eleventh power transistor, respectively, and the second terminal of the eleventh power transistor is grounded.

[0035] The second terminal of the second sub-power transistor is connected to the second terminal of the second sub-capacitor and the first terminal of the fourteenth power transistor, respectively, and the second terminal of the fourteenth power transistor is grounded.

[0036] The connection point between the second terminal of the third power transistor, the first terminal of the second power transistor, the second terminal of the tenth power transistor, and the second terminal of the ninth power transistor is the output terminal of the cascaded switched capacitor converter.

[0037] The connection point of the second terminal of the first sub-capacitor, the second terminal of the first sub-power transistor, and the first terminal of the seventh power transistor is the first sub-node of the first branch. The connection point of the second terminal of the second sub-capacitor, the second terminal of the second sub-power transistor, and the first terminal of the fourteenth power transistor is the second sub-node of the second branch.

[0038] The two ends of the auxiliary circuit are connected to the first sub-node and the second sub-node, respectively.

[0039] In some embodiments, the cascaded switched-capacitor converter is a 2N:1 cascaded switched-capacitor converter, where N is an integer greater than or equal to 4. The first branch includes a first power transistor, a second power transistor, a third power transistor, a first capacitor, N-1 first basic units, and a first input power transistor. The second branch includes an eighth power transistor, a ninth power transistor, a tenth power transistor, a third capacitor, N-1 second basic units, and a second input power transistor.

[0040] The first terminal of the first power transistor is connected to the second terminal of the second power transistor and the second terminal of the first capacitor. The second terminal of the first power transistor is grounded. The first terminal of the first capacitor and the first terminal of the third power transistor are connected to form the first connection point. The first terminal of the second power transistor and the second terminal of the third power transistor are connected to the output terminal of the cascaded switched capacitor converter.

[0041] The first terminal of the eighth power transistor is connected to the second terminal of the ninth power transistor and the second terminal of the third capacitor. The second terminal of the eighth power transistor is grounded. The first terminal of the third capacitor and the first terminal of the tenth power transistor are connected to form the second connection point. The first terminal of the ninth power transistor and the second terminal of the tenth power transistor are connected to the output terminal of the cascaded switched capacitor converter.

[0042] The first terminal of the first input power transistor and the first terminal of the second input power transistor are connected to the input terminal of the cascaded switched capacitor converter. The second terminal of the first input power transistor is connected to the first connection point and the second connection point in sequence through N-1 first basic units from the (N-1)th stage to the first stage. The second terminal of the second input power transistor is connected to the first connection point and the second connection point in sequence through N-1 second basic units from the (N-1)th stage to the first stage.

[0043] In some embodiments, each first basic unit has a first end, a second end, and a third end, and each second basic unit has a first end, a second end, and a third end.

[0044] The second terminal of the first input power transistor is connected to the first terminal of the first basic unit of the N-1th stage, and the second terminal of the second input power transistor is connected to the first terminal of the second basic unit of the N-1th stage.

[0045] The first connection point connects the third end of the first basic unit of the first level to the second end of the second basic unit of the first level, and the second connection point connects the third end of the second basic unit of the first level to the second end of the first basic unit of the first level.

[0046] In the first branch, except for the first end of the first basic unit of level N-1 and the second and third ends of the first basic unit of level 1, the first end of the first basic unit of the current level is connected to the third end of the first basic unit of the previous level and the second end of the second basic unit of the previous level. The current level can be any level from level 1 to level N-1. The second end of the first basic unit of the current level is connected to the first end of the second basic unit of the next level. The third end of the first basic unit of the current level is connected to the first end of the first basic unit of the next level.

[0047] In the second branch, except for the first end of the second basic unit of level N-1 and the second and third ends of the second basic unit of level 1, the first end of the current level second basic unit is connected to the third end of the previous level second basic unit and the second end of the previous level first basic unit. The current level can be any level from level 1 to level N-1. The second end of the current level second basic unit is connected to the first end of the next level first basic unit, and the third end of the current level second basic unit is connected to the first end of the next level second basic unit.

[0048] In some embodiments, each first basic unit includes a first unit power transistor, a second unit power transistor, a third unit power transistor, and a first unit capacitor. The first terminal of the first unit capacitor and the first terminal of the third unit power transistor are connected to form the first terminal of the first basic unit. The second terminal of the third unit power transistor is the second terminal of the first basic unit. The second terminal of the first unit capacitor is connected to the first terminal of the first unit power transistor and the second terminal of the second unit power transistor. The first terminal of the second unit power transistor is the third terminal of the first basic unit. The second terminal of the first unit power transistor is grounded.

[0049] Each second basic unit includes a fourth unit power transistor, a fifth unit power transistor, a sixth unit power transistor, and a second unit capacitor. The first terminal of the second unit capacitor and the first terminal of the sixth unit power transistor are connected to form the first terminal of the second basic unit. The second terminal of the sixth unit power transistor is the second terminal of the second basic unit. The second terminal of the second unit capacitor is connected to the first terminal of the fourth unit power transistor and the second terminal of the fifth unit power transistor. The first terminal of the fifth unit power transistor is the third terminal of the second basic unit. The second terminal of the fourth unit power transistor is grounded.

[0050] The two ends of the auxiliary circuit are respectively connected between the connection point of the first and second unit power transistors of the first basic unit of the N-1th stage and the connection point of the fourth and fifth unit power transistors of the second basic unit of the N-1th stage.

[0051] In some embodiments, the auxiliary circuit includes a fifteenth power transistor, a sixteenth power transistor, a seventeenth power transistor, an eighteenth power transistor, and an inductor; wherein, the first terminal of the fifteenth power transistor is connected to the first branch, the second terminal of the fifteenth power transistor is connected to the first terminal of the sixteenth power transistor and the first terminal of the inductor respectively, and the second terminal of the sixteenth power transistor is grounded; the second terminal of the inductor is connected to the first terminal of the seventeenth power transistor and the first terminal of the eighteenth power transistor respectively, the second terminal of the seventeenth power transistor is grounded, and the second terminal of the eighteenth power transistor is connected to the second branch.

[0052] In some embodiments, the auxiliary circuit includes a fifteenth power transistor, an eighteenth power transistor, a first diode, a second diode, and an inductor; wherein, the first terminal of the fifteenth power transistor is connected to the first branch, the second terminal of the fifteenth power transistor is connected to the first terminal of the first diode and the first terminal of the inductor respectively, and the second terminal of the first diode is grounded; the second terminal of the inductor is connected to the first terminal of the second diode and the first terminal of the eighteenth power transistor respectively, the second terminal of the second diode is grounded, and the second terminal of the eighteenth power transistor is connected to the second branch.

[0053] In some embodiments, the auxiliary circuit includes a fifteenth power transistor, an eighteenth power transistor, and an inductor; wherein, the first end of the fifteenth power transistor is connected to the first branch, the second end of the fifteenth power transistor is connected to the first end of the inductor, the second end of the inductor is connected to the first end of the eighteenth power transistor, and the second end of the eighteenth power transistor is connected to the second branch.

[0054] In some embodiments, the fifteenth, sixteenth, seventeenth, and eighteenth power transistors are all N-type power transistors; or, the fifteenth and eighteenth power transistors are P-type power transistors, and the sixteenth and seventeenth power transistors are N-type power transistors.

[0055] In some embodiments, the fifteenth and eighteenth power transistors are N-type or P-type power transistors.

[0056] In some embodiments, the fifteenth and eighteenth power transistors are N-type or P-type power transistors.

[0057] The above scheme is a feasible control timing sequence. Based on the above circuit structure, there are of course many other control timing sequences.

[0058] An auxiliary circuit is added between the two branches on the outside of a traditional cascaded converter. During the dead time when all main power transistors are off, the auxiliary circuit can transfer charge from one branch to the other, achieving zero-voltage turn-on of all main power transistors and reducing switching losses. The on-resistance of the power transistors in the added auxiliary circuit is much larger than that of the main power transistors, while the inductance of the inductor in the auxiliary circuit is very small, resulting in low package size and low cost. Therefore, this application can significantly reduce the switching losses of cascaded switched-capacitor converters and improve conversion efficiency by adding a low-cost auxiliary circuit, offering excellent performance benefits and commercial prospects. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of a traditional cascaded 4:1 switched capacitor converter.

[0060] Figure 2 This is a schematic diagram of the circuit structure of a cascaded 4:1 switched capacitor converter according to an embodiment of this application.

[0061] Figure 3 The following is a typical waveform diagram of a cascaded 4:1 switched capacitor converter according to an embodiment of this application.

[0062] Figure 4 This is an equivalent circuit diagram of the cascaded 4:1 switched capacitor converter operating in Stage 0 of this application embodiment.

[0063] Figure 5 This is an equivalent circuit diagram of the cascaded 4:1 switched capacitor converter operating in Stage 1 according to an embodiment of this application.

[0064] Figure 6 This is an equivalent circuit diagram of the cascaded 4:1 switched capacitor converter operating in Stage 2 according to an embodiment of this application.

[0065] Figure 7 This is an equivalent circuit diagram of the cascaded 4:1 switched capacitor converter operating in Stage 3 according to an embodiment of this application.

[0066] Figure 8 This is an equivalent circuit diagram of the cascaded 4:1 switched capacitor converter operating in Stage 4 according to an embodiment of this application.

[0067] Figure 9 This is an equivalent circuit diagram of the cascaded 4:1 switched capacitor converter operating in Stage 5 according to an embodiment of this application.

[0068] Figure 10 This is a schematic diagram of the circuit structure of a cascaded 8:1 switched capacitor converter according to an embodiment of this application.

[0069] Figure 11 Cascade type 2 of this application embodiment N :1. Schematic diagram of the circuit structure of a switched capacitor converter.

[0070] Figure 12 This is a schematic diagram of the circuit structure of various auxiliary circuits in embodiments of this application. Detailed Implementation

[0071] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this application are only for explaining this application and are not intended to limit this application.

[0072] like Figure 2 As shown in the embodiment of this application, the 4:1 cascaded switched capacitor converter includes a main power circuit and an auxiliary circuit. The main power circuit includes fourteen main power transistors (Q1A, Q1B, Q2A, Q2B, Q3A, Q3B, Q4A, Q4B, Q5A, Q5B, Q6A, Q6B, Q7A, and Q7B), four capacitors (C1A, C1B, C2A, and C2B), an input capacitor CIN, an output capacitor COUT, and an output load IOUT. The auxiliary circuit includes four auxiliary power transistors (QX1A, QX2A, QX1B, QX1B, and QX2B) and an inductor L. Each main power transistor has parasitic capacitance.

[0073] The first branch includes the first power transistor Q1A, the second power transistor Q2A, the third power transistor Q3A, the fourth power transistor Q4A, the fifth power transistor Q5A, the sixth power transistor Q6A, the seventh power transistor Q7A, the first capacitor C1A, and the second capacitor C2A; the second branch includes the eighth power transistor Q1B, the ninth power transistor Q2B, the tenth power transistor Q3B, the eleventh power transistor Q4B, the twelfth power transistor Q5B, the thirteenth power transistor Q6B, the fourteenth power transistor Q7B, the third capacitor C1B, and the fourth capacitor C2B.

[0074] The first terminal of the seventh power transistor Q7A and the first terminal of the fourteenth power transistor Q7B are the input terminals of the cascaded switched capacitor converter, which are connected to the external input voltage. The second terminal of the seventh power transistor Q7A is connected to the first terminal of the second capacitor C2A and the first terminal of the sixth power transistor Q6A, respectively. The second terminal of the fourteenth power transistor Q7B is connected to the first terminal of the fourth capacitor C2B and the first terminal of the thirteenth power transistor Q6B, respectively.

[0075] The second terminal of the sixth power transistor Q6A is connected to the first terminal of the tenth power transistor Q3B, the first terminal of the third capacitor C1B, and the first terminal of the twelfth power transistor Q5B, respectively. The second terminal of the thirteenth power transistor Q6B is connected to the first terminal of the third power transistor Q3A, the first terminal of the first capacitor C1A, and the first terminal of the fifth power transistor Q5A, respectively.

[0076] The second terminal of the fifth power transistor Q5A is connected to the second terminal of the second capacitor C2A and the first terminal of the fourth power transistor Q4A, respectively. The second terminal of the twelfth power transistor Q5B is connected to the second terminal of the fourth capacitor C2B and the first terminal of the eleventh power transistor Q4B, respectively. The second terminals of the fourth power transistor Q4A and the eleventh power transistor Q4B are grounded.

[0077] The second terminal of the third power transistor Q3A is connected to the first terminal of the second power transistor Q2A. The second terminal of the second power transistor Q2A is connected to the second terminal of the first capacitor C1A and the first terminal of the first power transistor Q1A. The second terminal of the first power transistor Q1A is grounded.

[0078] The second terminal of the tenth power transistor Q3B is connected to the first terminal of the ninth power transistor Q2B. The second terminal of the ninth power transistor Q2B is connected to the second terminal of the third capacitor C1B and the first terminal of the eighth power transistor Q1B. The second terminal of the eighth power transistor Q1B is grounded.

[0079] The connection point of the second terminal of the third power transistor Q3A, the first terminal of the second power transistor Q2A, the first terminal of the ninth power transistor Q2B, and the second terminal of the tenth power transistor Q3B is the output terminal of the cascaded switched capacitor converter.

[0080] The connection point of the second capacitor C2A, the fifth power transistor Q5A, and the fourth power transistor Q4A is the second node C2NA of the first branch, and the connection point of the fourth capacitor C2B, the twelfth power transistor Q5B, and the eleventh power transistor Q4B is the fourth node C2NB of the second branch.

[0081] The two ends of the auxiliary circuit are connected to the second node C2NA and the fourth node C2NB, respectively. For example, the first end of the fifteenth power transistor QX1A is connected to the second node C2NA of the first branch, the second end of the fifteenth power transistor QX1A is connected to the first end of the sixteenth power transistor QX2A and the first end of the inductor L, and the second end of the sixteenth power transistor QX2A is grounded; the second end of the inductor L is connected to the first end of the seventeenth power transistor QX2B and the first end of the eighteenth power transistor QX1B, the second end of the seventeenth power transistor QX2B is grounded, and the second end of the eighteenth power transistor QX1B is connected to the fourth node C2NB of the second branch.

[0082] Under steady-state operation, VIN = 4 * VOUT, VC1A = VOUT, VC1B = VOUT, VC2A = 2 * VOUT, VC2B = 2 * VOUT. Here, VIN represents the input voltage, VOUT represents the output voltage, VC1A represents the voltage difference across the first capacitor C1A, VC1B represents the voltage difference across the third capacitor C1B, VC2A represents the voltage difference across the second capacitor C2A, and VC2B represents the voltage difference across the fourth capacitor C2B.

[0083] Figure 3 This is the operating waveform of a 4:1 cascaded switched-capacitor converter within one switching cycle. There are six operating states sequentially within one cycle: stage0, stage1, stage2, stage3, stage4, and stage5. Signal PHA is the original clock signal with a 50% duty cycle; signal PHB is the inverted signal of signal PHA; signal PHA_DLY is the clock signal obtained by delaying signal PHA; and signal PHB_DLY is the clock signal obtained by delaying signal PHB. Signals Q1B, Q2A, Q3B, Q4B, Q6B, and Q7A represent the switching states of the eighth power transistor Q1B, the second power transistor Q2A, the tenth power transistor Q3B, the eleventh power transistor Q4B, the thirteenth power transistor Q6B, and the seventh power transistor Q7A, respectively. Signals Q1A, Q2B, Q3A, Q4A, Q6A, and Q7B represent the switching states of the first power transistor Q1A, the ninth power transistor Q2B, the third power transistor Q3A, the fourth power transistor Q4A, the sixth power transistor Q6A, and the fourteenth power transistor Q7B, respectively. Signal Q5A represents the switching state of the fifth power transistor Q5A, and signal Q5B represents the switching state of the twelfth power transistor Q5B. Signals QX1A, QX2A, QX1B, and QX2B represent the switching states of the fifteenth power transistor QX1A, the sixteenth power transistor QX2A, the eighteenth power transistor QX1B, and the seventeenth power transistor QX2B, respectively. Signals C2NA and C2NB represent the voltage waveforms of the second node C2NA in the first branch and the fourth node C2NB in ​​the second branch, respectively. Signals LXA and LXB represent the voltage waveforms of nodes LXA and LXB, respectively. Signal iL represents the current waveform flowing through inductor L.

[0084] Stage 0 (t0-t1): such as Figure 4As shown, in stage 0, the eighth power transistor Q1B, the second power transistor Q2A, the tenth power transistor Q3B, the eleventh power transistor Q4B, the fifth power transistor Q5A, the thirteenth power transistor Q6B, and the seventh power transistor Q7A are turned on, while the first power transistor Q1A, the ninth power transistor Q2B, the third power transistor Q3A, the fourth power transistor Q4A, the twelfth power transistor Q5B, the sixth power transistor Q6A, and the fourteenth power transistor Q7B are turned off (i.e., disconnected or not conducting). The first capacitor C1A is charging, the third capacitor C1B is discharging, the second capacitor C2A is charging, and the fourth capacitor C2B is discharging. In the auxiliary circuit section, the eighteenth power transistor QX1B and the sixteenth power transistor QX2A are turned on, while the fifteenth power transistor QX1A and the seventeenth power transistor QX2B are turned off. At this stage, the voltage of the first node C1NA is equal to the output voltage, the voltage of the second node C2NA of the first branch is equal to twice the output voltage, the voltages of the third node C1NB and the fourth node C2NB of the second branch are both zero, the voltages of nodes LXA and LXB are both zero, and the current flowing through the inductor L is zero.

[0085] Stage 1 (t1-t2): such as Figure 5 As shown, at time t1, the eighth power transistor Q1B, the second power transistor Q2A, the tenth power transistor Q3B, the eleventh power transistor Q4B, the thirteenth power transistor Q6B, and the seventh power transistor Q7A are off. At this time, among all the main power transistors, except for the fifth power transistor Q5A which remains on, the others are off. The first capacitor C1A, the third capacitor C1B, the second capacitor C2A, and the fourth capacitor C2B stop charging or discharging, maintaining their current voltage difference unchanged. The load current is provided by the discharge of the output capacitor COUT. The sixteenth power transistor QX2A and the seventeenth power transistor QX2B are off, while the fifteenth power transistor QX1A and the eighteenth power transistor QX1B are on.

[0086] Before time t1, the voltage at the first node C1NA is VOUT, the voltage at the second node C2NA of the first branch is 2*VOUT, and the voltages at the third node C1NB of the second branch and the fourth node C2NB of the second branch are zero. Starting from time t1, inductor L is connected between the second node C2NA of the first branch and the fourth node C2NB of the second branch. At this time, the parasitic capacitances of the second node C2NA and the fourth node C2NB of the first branch, along with inductor L, begin to resonate. The parasitic capacitance of the second node C2NA refers to the parasitic capacitance of the fifth power transistor Q5A connected to the second node C2NA. The voltage at the second node C2NA of the first branch resonates and decreases, causing the voltage at the first node C1NA to decrease through the fifth power transistor Q5A. The voltage at the fourth node C2NB of the second branch resonates and increases, causing the voltage at the third node C1NB to increase through the body diode of the twelfth power transistor Q5B. The current in inductor L gradually increases. When the voltage at the second node C2NA of the first branch drops to VOUT, the voltage at the second node C2NA of the first branch becomes the same as the voltage at the fourth node C2NB of the second branch, and the current in inductor L reaches its maximum value. At this time, the voltage at the first node C1NA drops to zero, turning off the drive signal of the fifth power transistor Q5A, and entering stage 2.

[0087] Stage 2 (t2-t3): such as Figure 6 As shown, at time t2, the voltage at the second node C2NA of the first branch is the same as the voltage at the fourth node C2NB of the second branch, and the current in inductor L reaches its maximum value. At this time, turning off the fifth power transistor Q5A turns off all the main power transistors, turning off the sixteenth power transistor QX2A and the seventeenth power transistor QX2B, while turning on the fifteenth power transistor QX1A and the eighteenth power transistor QX1B. The parasitic capacitance of the second node C2NA of the first branch, the parasitic capacitance of the fourth node C2NB of the second branch, and inductor L continue to resonate. At time t3, the voltage at the second node C2NA of the first branch resonates to zero, the voltage at the fourth node C2NB of the second branch resonates to 2*VOUT, and the current in inductor L drops to zero. The process then enters stage 3.

[0088] Stage 3 (t3-t4): such as Figure 7As shown, the first power transistor Q1A, the ninth power transistor Q2B, the third power transistor Q3A, the fourth power transistor Q4A, the twelfth power transistor Q5B, the sixth power transistor Q6A, and the fourteenth power transistor Q7B are turned on, while the eighth power transistor Q1B, the second power transistor Q2A, the tenth power transistor Q3B, the eleventh power transistor Q4B, the fifth power transistor Q5A, the thirteenth power transistor Q6B, and the seventh power transistor Q7A remain off. The first capacitor C1A is discharging, the third capacitor C1B is charging, the second capacitor C2A is charging, and the fourth capacitor C2B is discharging. In the auxiliary circuit section, the fifteenth power transistor QX1A and the seventeenth power transistor QX2B are turned on, while the eighteenth power transistor QX1B and the sixteenth power transistor QX2A are turned off. At this stage, the voltage of the third node C1NB is equal to the output voltage VOUT, the voltage of the fourth node C2NB of the second branch is equal to twice the output voltage VOUT, the voltage of the first node C1NA and the second node C2NA of the first branch is zero, the voltage of nodes LXA and LXB is zero, and the current flowing through the inductor L is zero.

[0089] Stage 4 (t4-t5): For example Figure 8 As shown, at time t4, the first power transistor Q1A, the ninth power transistor Q2B, the third power transistor Q3A, the fourth power transistor Q4A, the sixth power transistor Q6A, and the fourteenth power transistor Q7B are turned off. At this time, all the main power transistors except the twelfth power transistor Q5B remain on, while the others are off. The first capacitor C1A, the third capacitor C1B, the second capacitor C2A, and the fourth capacitor C2B stop charging or discharging, maintaining their current voltage. The load current is provided by the discharge of the output capacitor COUT. The sixteenth power transistor QX2A and the seventeenth power transistor QX2B are turned off, while the fifteenth power transistor QX1A and the eighteenth power transistor QX1B are on.

[0090] Before time t4, the voltage at the third node C1NB is the output voltage VOUT, the voltage at the fourth node C2NB of the second branch is 2*VOUT, and the voltages at the first node C1NA and the second node C2NA of the first branch are zero. Starting at time t4, inductor L is connected between the second node C2NA of the first branch and the fourth node C2NB of the second branch. At this time, the parasitic capacitances of the second node C2NA and the fourth node C2NB of the second branch, along with inductor L, begin to resonate. The voltage at the fourth node C2NB of the second branch decreases resonantly, and this decrease is driven by the twelfth power transistor Q5B, causing the voltage at the third node C1NB to decrease. The voltage at the second node C2NA of the first branch increases resonantly, and this increase is driven by the body diode of the fifth power transistor Q5A, causing the voltage at the first node C1NA of the first branch to increase. The current in inductor L gradually increases in a negative direction. When the voltage at the fourth node C2NB of the second branch drops to the output voltage VOUT, the voltage at the fourth node C2NB of the second branch is the same as the voltage at the second node C2NA of the first branch, and the current in inductor L reaches its negative maximum value. At this time, the voltage at the third node C1NB drops to zero, turning off the drive signal of the twelfth power transistor Q5B, and entering stage 5.

[0091] Stage 5 (t5-t0): For example... Figure 9 As shown, at time t5, the voltage at the second node C2NA of the first branch is the same as the voltage at the fourth node C2NB of the second branch, and the current in inductor L reaches its negative maximum value. At this time, turning off the twelfth power transistor Q5B turns off all main power transistors, turning off the sixteenth power transistor QX2A and the seventeenth power transistor QX2B, while turning on the fifteenth power transistor QX1A and the eighteenth power transistor QX1B. The parasitic capacitance of the second node C2NA of the first branch, the parasitic capacitance of the fourth node C2NB of the second branch, and inductor L continue to resonate. At time t0, the voltage at the fourth node C2NB of the second branch resonates to zero, the voltage at the second node C2NA of the first branch resonates to 2*VOUT, and the current in inductor L drops to zero. The process then enters stage 0.

[0092] The structure of this application controls the fifteenth power transistor QX1A, the sixteenth power transistor QX2A, the eighteenth power transistor QX1B, and the seventeenth power transistor QX2B through the aforementioned control timing. During stage 1 and stage 2, the charge on the first node C1NA and the second node C2NA of the first branch is completely transferred to the third node C1NB and the fourth node C2NB of the second branch through inductor L. During stage 4 and stage 5, the charge on the third node C1NB and the fourth node C2NB of the second branch is completely transferred to the first branch through inductor L. The first node C1NA and the second node C2NA of the first branch ensure that the voltage difference between the first power transistor Q1A, the eighth power transistor Q1B, the second power transistor Q2A, the ninth power transistor Q2B, the third power transistor Q3A, the tenth power transistor Q3B, the fourth power transistor Q4A, the eleventh power transistor Q4B, the fifth power transistor Q5A, the twelfth power transistor Q5B, the sixth power transistor Q6A, the thirteenth power transistor Q6B, the seventh power transistor Q7A, and the fourteenth power transistor Q7B is zero before each turn-on, which greatly reduces switching losses and improves the conversion efficiency of the cascaded switched capacitor converter.

[0093] exist Figure 2 Based on the cascaded 4:1 switched-capacitor converter shown, a cascaded 8:1 switched-capacitor converter can be realized by adding six main power transistors and two capacitors, such as... Figure 10 As shown. This converter can employ and Figure 2 The same auxiliary circuit and similar control method are used to achieve zero-voltage turn-on of all main power transistors.

[0094] Figure 10 The cascaded 8:1 switched capacitor converter shown includes an auxiliary circuit, a first branch, and a second branch. The first branch includes a first power transistor Q1A, a second power transistor Q2A, a third power transistor Q3A, a fourth power transistor Q4A, a fifth power transistor Q5A, a sixth power transistor Q6A, a seventh power transistor Q7A, a first sub-power transistor Q8A, a third sub-power transistor Q9A, a fifth sub-power transistor Q10A, a first capacitor C1A, a second capacitor C2A, and a first sub-capacitor C3A. The second branch includes an eighth power transistor Q1B, a ninth power transistor Q2B, a tenth power transistor Q3B, an eleventh power transistor Q4B, a twelfth power transistor Q5B, a thirteenth power transistor Q6B, a fourteenth power transistor Q7B, a second sub-power transistor Q8B, a fourth sub-power transistor Q9B, a sixth sub-power transistor Q10B, a third capacitor C1B, a fourth capacitor C2B, and a second sub-capacitor C3B. All power transistors in both the first and second branches are main power transistors, and each main power transistor has parasitic capacitance.

[0095] The first terminal of the fifth sub-power transistor Q10A and the first terminal of the sixth sub-power transistor Q10B are connected to the input terminal of the cascaded 8:1 switched capacitor converter, and the input terminal is connected to the external input voltage VIN. The second terminal of the fifth sub-power transistor Q10A is connected to the first terminal of the first sub-capacitor C3A and the first terminal of the third sub-power transistor Q9A, respectively. The second terminal of the sixth power transistor Q10B is connected to the first terminal of the second sub-capacitor C3B and the first terminal of the fourth sub-power transistor Q9B, respectively.

[0096] The second terminal of the third sub-power transistor Q9A is connected to the first terminal of the thirteenth power transistor Q6B, the first terminal of the fourth capacitor C2B, and the first terminal of the second sub-power transistor Q8B, respectively. The second terminal of the fourth sub-power transistor Q9B is connected to the first terminal of the sixth power transistor Q6A, the first terminal of the second capacitor C2A, and the first terminal of the first sub-power transistor Q8A, respectively.

[0097] The second terminal of the sixth power transistor Q6A is connected to the first terminal of the tenth power transistor Q3B, the first terminal of the third capacitor C1B, and the first terminal of the twelfth power transistor Q5B, respectively. The second terminal of the thirteenth power transistor Q6B is connected to the first terminal of the third power transistor Q3A, the first terminal of the first capacitor C1A, and the first terminal of the fifth power transistor Q5A, respectively.

[0098] The second terminal of the third power transistor Q3A is connected to the first terminal of the second power transistor Q2A. The second terminal of the second power transistor Q2A is connected to the second terminal of the first capacitor C1A and the first terminal of the first power transistor Q1A. The second terminal of the first power transistor Q1A is grounded.

[0099] The second terminal of the fifth power transistor Q5A is connected to the second terminal of the second capacitor C2A and the first terminal of the fourth power transistor Q4A, respectively. The second terminal of the fourth power transistor Q4A is grounded.

[0100] The second terminal of the first sub-power transistor Q8A is connected to the second terminal of the first sub-capacitor C3A and the first terminal of the seventh power transistor Q7A, respectively. The second terminal of the seventh power transistor Q7A is grounded.

[0101] The second terminal of the tenth power transistor Q3B is connected to the first terminal of the ninth power transistor Q2B. The second terminal of the ninth power transistor Q2B is connected to the second terminal of the third capacitor C1B and the first terminal of the eighth power transistor Q1B. The second terminal of the eighth power transistor Q1B is grounded.

[0102] The second terminal of the twelfth power transistor Q5B is connected to the second terminal of the fourth capacitor C2B and the first terminal of the eleventh power transistor Q4B, respectively. The second terminal of the eleventh power transistor Q4B is grounded.

[0103] The second terminal of the second sub-power transistor Q8B is connected to the second terminal of the second sub-capacitor C3B and the first terminal of the fourteenth power transistor Q7B, respectively. The second terminal of the fourteenth power transistor Q7B is grounded.

[0104] The connection point of the second terminal of the third power transistor Q3A, the first terminal of the second power transistor Q2A, the second terminal of the tenth power transistor Q3B, and the second terminal of the ninth power transistor Q2B is the output terminal VOUT of the cascaded switched capacitor converter.

[0105] The connection point of the second terminal of the first sub-capacitor C3A, the second terminal of the first sub-power transistor Q8A, and the first terminal of the seventh power transistor Q7A is the first sub-node C3NA of the first branch. The connection point of the second terminal of the second sub-capacitor C3B, the second terminal of the second sub-power transistor Q8B, and the first terminal of the fourteenth power transistor Q7B is the second sub-node C3NB of the second branch.

[0106] The two ends of the auxiliary circuit are respectively connected to the first child node C3NA and the second child node C3NB. The auxiliary circuit structure in this embodiment is similar to... Figure 2 The auxiliary circuits described in the embodiments have the same structure.

[0107] exist Figure 2 Based on the novel 4:1 cascaded switched-capacitor converter shown, by further increasing the number of main power transistors and capacitors, it is possible to achieve 2 N 1. Switched capacitor converter, such as Figure 11 As shown. This converter can employ and Figure 2 The same auxiliary circuit and similar control method are used to achieve zero-voltage turn-on of all main power transistors. Here, N is an integer greater than or equal to 2.

[0108] When N=2, 2 N A 4:1 cascaded switched-capacitor converter is a type of switched-capacitor converter, such as... Figure 2 As shown, when N=3, 2 N An 8:1 cascaded switched-capacitor converter is a type of switched-capacitor converter, such as... Figure 10 As shown, when N is an integer greater than or equal to 4, 2 N The circuit structure diagram of a cascaded switched capacitor converter is shown in Figure 11.

[0109] like Figure 11 As shown, 2 NThe cascaded switched-capacitor converter includes an auxiliary circuit, a first branch, and a second branch. The first branch includes a first power transistor Q1A, a second power transistor Q2A, a third power transistor Q3A, a first capacitor C1A, N-1 first basic units, and a first input power transistor Q(3N+1)A. The second branch includes an eighth power transistor Q1B, a ninth power transistor Q2B, a tenth power transistor Q3B, a third capacitor C1B, N-1 second basic units, and a second input power transistor Q(3N+1)B. All power transistors in both the first and second branches are main power transistors, and each main power transistor has parasitic capacitance.

[0110] The first terminal of the first power transistor Q1A is connected to the second terminal of the second power transistor Q2A and the second terminal of the first capacitor C1A. The second terminal of the first power transistor Q1A is grounded. The first terminal of the first capacitor C1A and the first terminal of the third power transistor Q3A are connected at the first connection point. The first terminal of the second power transistor Q2A and the second terminal of the third power transistor Q3A are connected at point 2. N :1. Output terminal of the cascaded switched-capacitor converter. The first terminal of the eighth power transistor Q1B is connected to the second terminal of the ninth power transistor Q2B and the second terminal of the third capacitor C1B. The second terminal of the eighth power transistor Q1B is grounded. The first terminal of the third capacitor C1B and the first terminal of the tenth power transistor Q3B are connected as the second connection point. The first terminal of the ninth power transistor Q2B and the second terminal of the tenth power transistor Q3B are connected to 2. N :1 Output terminal of a cascaded switched capacitor converter.

[0111] The first terminal of the first input power transistor Q(3N+1)A and the first terminal of the second input power transistor Q(3N+1)B are connected to 2 N :1. The input terminals of the switched capacitor converter are as follows: the second terminal of the first input power transistor Q(3N+1)A is connected to the first connection point and the second connection point sequentially through N-1 first basic units from the (N-1)th stage to the first stage; the second terminal of the second input power transistor Q(3N+1)B is connected to the first connection point and the second connection point sequentially through N-1 second basic units from the (N-1)th stage to the first stage. Specifically, the second terminal of the first input power transistor Q(3N+1)A is connected to the (N-1)th stage first basic unit, and the first stage first basic unit is connected to the first connection point and the second connection point; the second terminal of the second input power transistor Q(3N+1)B is connected to the (N-1)th stage second basic unit, and the first stage first basic unit is connected to the second connection point and the second connection point.

[0112] Each first basic unit has a first end, a second end, and a third end, and each second basic unit has a first end, a second end, and a third end.

[0113] The second terminal of the first input power transistor Q(3N+1)A is connected to the first terminal of the first basic unit of the N-1th stage, and the second terminal of the second input power transistor Q(3N+1)B is connected to the first terminal of the second basic unit of the N-1th stage.

[0114] The first connection point connects the third end of the first basic unit of the first level to the second end of the second basic unit of the first level, and the second connection point connects the third end of the second basic unit of the first level to the second end of the first basic unit of the first level.

[0115] In the first branch, except for the first end of the first basic unit of level N-1 and the second and third ends of the first basic unit of level 1, the first end of the first basic unit of the current level is connected to the third end of the first basic unit of the previous level and the second end of the second basic unit of the previous level. The current level is any level from level 1 to level N-1. The second end of the first basic unit of the current level is connected to the first end of the second basic unit of the next level, and the third end of the first basic unit of the current level is connected to the first end of the first basic unit of the next level.

[0116] In the second branch, except for the first end of the second basic unit of level N-1 and the second and third ends of the second basic unit of level 1, the first end of the second basic unit of the current level is connected to the third end of the second basic unit of the previous level and the second end of the first basic unit of the previous level. The current level is any level from level 1 to level N-1. The second end of the second basic unit of the current level is connected to the first end of the first basic unit of the next level, and the third end of the second basic unit of the current level is connected to the first end of the second basic unit of the next level.

[0117] For example, each first basic unit includes a first unit power transistor, a second unit power transistor, a third unit power transistor, and a first unit capacitor. The first terminal of the first unit capacitor and the first terminal of the third unit power transistor are connected to form the first terminal of the first basic unit. The second terminal of the third unit power transistor is the second terminal of the first basic unit. The second terminal of the first unit capacitor is connected to the first terminal of the first unit power transistor and the second terminal of the second unit power transistor. The first terminal of the second unit power transistor is the third terminal of the first basic unit. The second terminal of the first unit power transistor is grounded.

[0118] For example, the first power transistor, second power transistor, third power transistor, and first capacitor of the first basic unit of the first stage are the fourth power transistor Q4A, the fifth power transistor Q5A, the sixth power transistor Q6A, and the second capacitor C2A, respectively.

[0119] The first power transistor, second power transistor, third power transistor, and first capacitor of the first basic unit of the second stage are the seventh power transistor Q7A, the first sub-power transistor Q8A, the third sub-power transistor Q9A, and the first sub-capacitor C3A, respectively.

[0120] The first power transistor, second power transistor, third power transistor, and first capacitor of the first basic unit of the N-1 level are respectively the 3M-4 sub-power transistor Q(3N-2)A, the 3M-2 sub-power transistor Q(3N-1)A, the 3M sub-power transistor Q(3N)A, and the M sub-capacitor C(N)A, where M = 2(N-2)-1.

[0121] For example, each second basic unit includes a fourth unit power transistor, a fifth unit power transistor, a sixth unit power transistor, and a second unit capacitor. The first terminal of the second unit capacitor and the first terminal of the sixth unit power transistor are connected to form the first terminal of the second basic unit. The second terminal of the sixth unit power transistor is the second terminal of the second basic unit. The second terminal of the second unit capacitor is connected to the first terminal of the fourth unit power transistor and the second terminal of the fifth unit power transistor. The first terminal of the fifth unit power transistor is the third terminal of the second basic unit. The second terminal of the fourth unit power transistor is grounded.

[0122] The fourth, fifth, and sixth power transistors of the second basic unit of the first stage, and the second unit capacitor are respectively the eleventh power transistor Q4B, the twelfth power transistor Q5B, the thirteenth power transistor Q6B, and the fourth capacitor C2B.

[0123] The fourth, fifth, and sixth power transistors of the second basic unit of the second stage are the fourteenth power transistor Q7B, the second sub-power transistor Q8B, the fourth sub-power transistor Q9B, and the second sub-capacitor C3B, respectively.

[0124] The fourth, fifth, and sixth power transistors of the second basic unit of the N-1 level, and the second unit capacitor are respectively the 3K-6 sub-power transistor Q(3N-2)B, the 3K-4 sub-power transistor Q(3N-1)B, the 3K-2 sub-power transistor Q(3N)B, and the Kth sub-capacitor C(N)B, where K = 2(N-2).

[0125] The two ends of the auxiliary circuit are respectively connected to the connection point C(N)NA of the first and second unit power transistors of the first basic unit of the N-1 level and the connection point C(N)NB of the fourth and fifth unit power transistors of the second basic unit of the N-1 level.

[0126] Under steady-state operating conditions, 2 N The input voltage at the input terminal of the cascaded switched capacitor converter is 2. N *VOUT, the voltage differences between the first capacitor C1A, the second capacitor C2A, the first sub-capacitor C3A, ..., the Mth sub-capacitor C(N)A are respectively: VOUT, 2*VOUT, 4*VOUT, ..., 2 (N-1)*VOUT. The voltage differences between the third capacitor C1B, the fourth capacitor C2B, the second sub-capacitor C3B, ..., the Kth sub-capacitor C(N)B are respectively: VOUT, 2*VOUT, 4*VOUT, ..., 2 (N-1) *VOUT.

[0127] In all embodiments of this application, the power transistors and sub-power transistors of the first branch and the second branch are all main power transistors. All main power transistors have parasitic capacitances, and the main power transistors can be either switching transistors or diodes.

[0128] exist Figure 10 and Figure 11 As can be seen from the structure shown, after connecting the two outermost branches through auxiliary circuits, the corresponding circuit structure is the same as that in the embodiment of this application. Figure 2 The auxiliary circuits have the same structure.

[0129] Figure 2 The auxiliary circuit shown includes four NMOS transistors and an inductor. It enables the transfer of charge from one branch to another during the dead time when all main power transistors are off, achieving zero-voltage turn-on for all main power transistors and reducing switching losses. Besides... Figure 2 Besides the auxiliary circuit in the diagram, which can achieve this zero-voltage turn-on function, there are various other types of auxiliary circuits that can also achieve this function. For example... Figure 12 As shown, there are several different auxiliary circuits.

[0130] Optionally, such as Figure 12 As shown, the auxiliary circuit may include a fifteenth power transistor, a sixteenth power transistor, a seventeenth power transistor, an eighteenth power transistor, and an inductor. The first terminal of the fifteenth power transistor is connected to the first branch, and the second terminal of the fifteenth power transistor is connected to the first terminal of the sixteenth power transistor and the first terminal of the inductor, respectively. The second terminal of the sixteenth power transistor is grounded. The second terminal of the inductor is connected to the first terminals of the seventeenth and eighteenth power transistors, respectively. The second terminal of the seventeenth power transistor is grounded, and the second terminal of the eighteenth power transistor is connected to the second branch. The fifteenth, sixteenth, seventeenth, and eighteenth power transistors can all be N-type, such as... Figure 12 As shown in the auxiliary ZVS circuit A, alternatively, the fifteenth and eighteenth power transistors can both be P-type power transistors, and the sixteenth and seventeenth power transistors can both be N-type power transistors, as shown in the diagram. Figure 12 The auxiliary ZVS circuit is shown in Figure D.

[0131] Optionally, such as Figure 12As shown, the auxiliary circuit may further include a fifteenth power transistor, an eighteenth power transistor, a first diode, a second diode, and an inductor; wherein, the first terminal of the fifteenth power transistor is connected to the first branch, the second terminal of the fifteenth power transistor is connected to the first terminal of the first diode and the first terminal of the inductor respectively, the second terminal of the first diode is grounded, wherein the first terminal of the first diode is the negative terminal and the second terminal of the first diode is the positive terminal; the second terminal of the inductor is connected to the first terminal of the second diode and the first terminal of the eighteenth power transistor respectively, the second terminal of the second diode is grounded, the second terminal of the eighteenth power transistor is connected to the second branch, wherein the first terminal of the second diode is the negative terminal and the second terminal of the second diode is the positive terminal. The fifteenth and eighteenth power transistors can both be N-type power transistors, such as... Figure 12 As shown in the auxiliary ZVS circuit B, or, the fifteenth and eighteenth power transistors can both be P-type power transistors, such as... Figure 12 The auxiliary ZVS circuit is shown in Figure E.

[0132] Optionally, the auxiliary circuit may further include a fifteenth power transistor, an eighteenth power transistor, and an inductor; wherein the first terminal of the fifteenth power transistor is connected to the first branch, the second terminal of the fifteenth power transistor is connected to the first terminal of the inductor, the second terminal of the inductor is connected to the first terminal of the eighteenth power transistor, and the second terminal of the eighteenth power transistor is connected to the second branch. The fifteenth and eighteenth power transistors can both be N-type, such as... Figure 12 As shown in the auxiliary ZVS circuit C, or, the fifteenth and eighteenth power transistors can both be P-type, such as... Figure 12 The auxiliary ZVS circuit is shown in Figure F.

[0133] This demonstrates that the specific implementation circuits are diverse. Therefore, after understanding the content of this application, those skilled in the art can easily conceive of various modifications, variations, or equivalents of the above examples, but they should still be subject to the limitations set forth in the claims and any equivalents.

Claims

1. A cascaded switched-capacitor converter, comprising an auxiliary circuit, a first branch and a second branch, the auxiliary circuit being connected between the first branch and the second branch, power tubes of the first branch and the second branch being main power tubes, the auxiliary circuit being configured to transfer charge of one branch to another branch in a dead time when all the main power tubes are off, so that voltage differences across the main power tubes become zero and the main power tubes are turned on with zero voltage. wherein The cascaded switched-capitor converter is a 4:1 cascaded switched-capacitor converter, the first branch comprises a first power tube, a second power tube, a third power tube, a fourth power tube, a fifth power tube, a sixth power tube, a seventh power tube, a first capacitor and a second capacitor, and the second branch comprises an eighth power tube, a ninth power tube, a tenth power tube, an eleventh power tube, a twelfth power tube, a thirteenth power tube, a fourteenth power tube, a third capacitor and a fourth capacitor. A first end of the seventh power tube and a first end of the fourteenth power tube are input terminals of the cascaded switched-capacitor converter, the input terminals are connected with an external input voltage, a second end of the seventh power tube is connected with a first end of the second capacitor and a first end of the sixth power tube respectively, and a second end of the fourteenth power tube is connected with a first end of the fourth capacitor and a first end of the thirteenth power tube respectively. A second end of the sixth power tube is connected with a first end of the tenth power tube, a first end of the third capacitor and a first end of the twelfth power tube respectively, a second end of the thirteenth power tube is connected with a first end of the third power tube, a first end of the first capacitor and a first end of the fifth power tube respectively. A second end of the fifth power tube is connected with a second end of the second capacitor and a first end of the fourth power tube respectively, a second end of the twelfth power tube is connected with a second end of the fourth capacitor and a first end of the eleventh power tube respectively, and a second end of the fourth power tube and a second end of the eleventh power tube are grounded. A second end of the third power tube is connected with a first end of the second power tube, a second end of the second power tube is connected with a second end of the first capacitor and a first end of the first power tube respectively, and a second end of the first power tube is grounded. A second end of the tenth power tube is connected with a first end of the ninth power tube, a second end of the ninth power tube is connected with a second end of the third capacitor and a first end of the eighth power tube respectively, and a second end of the eighth power tube is grounded. A connection point of the second end of the third power tube, the first end of the second power tube, the first end of the ninth power tube and the second end of the tenth power tube is an output terminal of the cascaded switched-capacitor converter. A connection point of a second end of the second capacitor, a second end of the fifth power tube and a first end of the fourth power tube is a second node of the first branch, and a connection point of a second end of the fourth capacitor, a second end of the twelfth power tube and a first end of the eleventh power tube is a fourth node of the second branch. The auxiliary circuit is connected with the second node and the fourth node respectively.

2. The cascaded switched-capacitor converter of claim 1, wherein, The auxiliary circuit comprises a fifteenth power tube, a sixteenth power tube, a seventeenth power tube, an eighteenth power tube and an inductor; the first end of the fifteenth power tube is connected with the second node; the second end of the fifteenth power tube is connected with the first end of the sixteenth power tube and the first end of the inductor respectively; the second end of the sixteenth power tube is grounded; the second end of the inductor is connected with the first end of the seventeenth power tube and the first end of the eighteenth power tube respectively; the second end of the seventeenth power tube is grounded; and the second end of the eighteenth power tube is connected with the fourth node.

3. The cascaded switched-capacitor converter of claim 2, wherein, The working timing of the cascade type switched capacitor converter comprises six stages, which are as follows: In the first stage, the second power tube, the fifth power tube, the seventh power tube, the eighth power tube, the tenth power tube, the eleventh power tube, the thirteenth power tube, the sixteenth power tube and the eighteenth power tube are turned on, and other power tubes are turned off; The first capacitor and the second capacitor are in a charging state, the third capacitor and the fourth capacitor are in a discharging state, and the inductor current is 0; In the second stage, the fifth power tube, the fifteenth power tube and the eighteenth power tube are turned on, and other power tubes are turned off; The inductor current rises, and the second stage ends when the inductor current rises to a maximum value; In the third stage, the fifteenth power tube and the eighteenth power tube are turned on, and other power tubes are turned off; The inductor current falls, and the third stage ends when the inductor current falls to 0; In the fourth stage, the first power tube, the third power tube, the fourth power tube, the sixth power tube, the ninth power tube, the twelfth power tube, the fourteenth power tube, the fifteenth power tube and the seventeenth power tube are turned on, and other power tubes are turned off; The first capacitor and the fourth capacitor are in a discharging state, and the second capacitor and the third capacitor are in a charging state; The inductor current is 0; In the fifth stage, the twelfth power tube, the fifteenth power tube and the eighteenth power tube are turned on, and other power tubes are turned off; The inductor current rises, and the fifth stage ends when the inductor current rises to a maximum value; In the sixth stage, the fifteenth power tube and the eighteenth power tube are turned on, and other power tubes are turned off; The inductor current falls, and the sixth stage ends when the inductor current falls to 0, returning to the first stage.

4. The switched capacitor converter of claim 2 or 3, wherein, The fifteenth power tube, the sixteenth power tube, the seventeenth power tube and the eighteenth power tube are all N-type power tubes; or the fifteenth power tube and the eighteenth power tube are P-type, and the sixteenth power tube and the seventeenth power tube are N-type.

5. The cascaded switched-capacitor converter of claim 1, wherein, The first branch comprises a first power tube, a second power tube, a third power tube, a fourth power tube, a fifth power tube, a sixth power tube, a seventh power tube, a first sub power tube, a third sub power tube, a fifth sub power tube, a first capacitor, a second capacitor and a first sub capacitor; the second branch comprises an eighth power tube, a ninth power tube, a tenth power tube, an eleventh power tube, a twelfth power tube, a thirteenth power tube, a fourteenth power tube, a second sub power tube, a fourth sub power tube, a sixth sub power tube, a third capacitor, a fourth capacitor and a second sub capacitor; The first end of the fifth sub power tube and the first end of the sixth sub power tube are input ends of the cascade switched capacitor converter, and the input ends are connected with an external input voltage connection; the second end of the fifth sub power tube is connected with the first end of the first sub capacitor and the first end of the third sub power tube respectively; and the second end of the sixth sub power tube is connected with the first end of the second sub capacitor and the first end of the fourth sub power tube respectively; The second end of the third sub power tube is connected with the first end of the thirteenth power tube, the first end of the fourth capacitor and the first end of the second sub power tube respectively; the second end of the fourth sub power tube is connected with the first end of the sixth power tube, the first end of the second capacitor and the first end of the first sub power tube respectively; The second end of the sixth power tube is connected with the first end of the tenth power tube, the first end of the third capacitor and the first end of the twelfth power tube respectively; and the second end of the thirteenth power tube is connected with the first end of the third power tube, the first end of the first capacitor and the first end of the fifth power tube respectively; The second end of the third power tube is connected with the first end of the second power tube; the second end of the second power tube is connected with the second end of the first capacitor and the first end of the first power tube respectively; and the second end of the first power tube is grounded; The second end of the fifth power tube is connected with the second end of the second capacitor and the first end of the fourth power tube respectively; and the second end of the fourth power tube is grounded; The second end of the first sub power tube is connected with the second end of the first sub capacitor and the first end of the seventh power tube respectively; and the second end of the seventh power tube is grounded; The second end of the tenth power tube is connected with the first end of the ninth power tube; the second end of the ninth power tube is connected with the second end of the third capacitor and the first end of the eighth power tube respectively; and the second end of the eighth power tube is grounded; The second end of the twelfth power tube is connected with the second end of the fourth capacitor and the first end of the eleventh power tube respectively; and the second end of the eleventh power tube is grounded; The second end of the second sub power tube is connected with the second end of the second sub capacitor and the first end of the fourteenth power tube respectively; and the second end of the fourteenth power tube is grounded. The connection point of the second end of the third power tube, the first end of the second power tube, the second end of the tenth power tube and the second end of the ninth power tube is an output end of the cascade type switched capacitor converter; The connection point of the second end of the first sub-capacitor, the second end of the first sub-power tube and the first end of the seventh power tube is a first sub-node of the first branch, and the connection point of the second end of the second sub-capacitor, the second end of the second sub-power tube and the first end of the fourteenth power tube is a second sub-node of the second branch; The first end of the first power tube is connected to the second end of the second power tube and the second end of the first capacitor respectively, the second end of the first power tube is grounded, the first end of the first capacitor and the first end of the third power tube are connected as a first connection point, and the first end of the second power tube and the second end of the third power tube are connected to the output end of the cascade type switched capacitor converter; 6. The cascaded switched-capacitor converter of claim 1, wherein, The cascade type switched capacitor converter is 2 N :1 cascade type switched capacitor converter, wherein N is an integer greater than or equal to 4, the first branch includes a first power tube, a second power tube, a third power tube, a first capacitor, N-1 first basic units and a first input power tube, the second branch includes an eighth power tube, a ninth power tube, a tenth power tube, a third capacitor, N-1 second basic units and a second input power tube; The first end of the eighth power tube is connected to the second end of the ninth power tube and the second end of the third capacitor respectively, the second end of the eighth power tube is grounded, the first end of the third capacitor and the first end of the tenth power tube are connected as a second connection point, and the first end of the ninth power tube and the second end of the tenth power tube are connected to the output end of the cascade type switched capacitor converter; The first end of the first input power tube and the first end of the second input power tube are connected to the input end of the cascade type switched capacitor converter, the second end of the first input power tube is sequentially connected to the first connection point and the second connection point through the N-1 first basic units in the order from the N-1 level first basic unit to the 1 level first basic unit, and the second end of the second input power tube is sequentially connected to the first connection point and the second connection point through the N-1 second basic units in the order from the N-1 level second basic unit to the 1 level second basic unit. Each first basic unit has a first end, a second end and a third end, and each second basic unit has a first end, a second end and a third end; 7. The cascaded switched-capacitor converter of claim 6, wherein, The second end of the first input power tube is connected to the first end of the N-1 level first basic unit, and the second end of the second input power tube is connected to the first end of the N-1 level second basic unit; The first connection point is connected to the third end of the 1 level first basic unit and the second end of the 1 level second basic unit, and the second connection point is connected to the third end of the 1 level second basic unit and the second end of the 1 level first basic unit. ​ In the first branch, except for the first end of the N-1th first basic unit and the second end and the third end of the 1st first basic unit, the first end of the first basic unit of the current level is connected to the third end of the first basic unit of the previous level and the second end of the second basic unit of the previous level, wherein the current level is any one of the 1st to the N-1th level, the second end of the first basic unit of the current level is connected to the first end of the second basic unit of the next level, and the third end of the first basic unit of the current level is connected to the first end of the first basic unit of the next level. In the second branch, except for the first end of the N-1th second basic unit and the second end and the third end of the 1st second basic unit, the first end of the second basic unit of the current level is connected to the third end of the second basic unit of the previous level and the second end of the first basic unit of the previous level, wherein the current level is any one of the 1st to the N-1th level, the second end of the second basic unit of the current level is connected to the first end of the first basic unit of the next level, and the third end of the second basic unit of the current level is connected to the first end of the second basic unit of the next level.

8. The cascaded switched-capacitor converter of claim 7, wherein, Each first basic unit comprises a first unit power tube, a second unit power tube, a third unit power tube, and a first unit capacitor, the first end of the first unit capacitor and the first end of the third unit power tube are connected as the first end of the first basic unit, the second end of the third unit power tube is the second end of the first basic unit, the second end of the first unit capacitor is connected to the first end of the first unit power tube and the second end of the second unit power tube respectively, the first end of the second unit power tube is the third end of the first basic unit, and the second end of the first unit power tube is grounded. Each second basic unit comprises a fourth unit power tube, a fifth unit power tube, a sixth unit power tube, and a second unit capacitor, the first end of the second unit capacitor and the first end of the sixth unit power tube are connected as the first end of the second basic unit, the second end of the sixth unit power tube is the second end of the second basic unit, the second end of the second unit capacitor is connected to the first end of the fourth unit power tube and the second end of the fifth unit power tube respectively, the first end of the fifth unit power tube is the third end of the second basic unit, and the second end of the fourth unit power tube is grounded. The two ends of the auxiliary circuit are respectively connected between the connection point of the first unit power tube and the second unit power tube of the N-1th first basic unit and the connection point of the fourth unit power tube and the fifth unit power tube of the N-1th second basic unit.

9. The cascaded switched-capacitor converter according to any one of claims 1, 5 and 6-8, wherein, The auxiliary circuit comprises a fifteenth power tube, a sixteenth power tube, a seventeenth power tube, an eighteenth power tube and an inductor; the first end of the fifteenth power tube is connected with the first branch, the second end of the fifteenth power tube is connected with the first end of the sixteenth power tube and the first end of the inductor respectively, and the second end of the sixteenth power tube is grounded; the second end of the inductor is connected with the first end of the seventeenth power tube and the first end of the eighteenth power tube respectively, the second end of the seventeenth power tube is grounded, and the second end of the eighteenth power tube is connected with the second branch.

10. The cascaded switched-capacitor converter of any one of claims 1, 5, and 6-8, wherein, The auxiliary circuit comprises a fifteenth power tube, an eighteenth power tube, a first diode, a second diode and an inductor; the first end of the fifteenth power tube is connected with the first branch, the second end of the fifteenth power tube is connected with the first end of the first diode and the first end of the inductor respectively, and the second end of the first diode is grounded; the second end of the inductor is connected with the first end of the second diode and the first end of the eighteenth power tube respectively, the second end of the second diode is grounded, and the second end of the eighteenth power tube is connected with the second branch.

11. The cascaded switched-capacitor converter according to any one of claims 1, 5 and 6-8, wherein, The auxiliary circuit comprises a fifteenth power tube, an eighteenth power tube and an inductor; the first end of the fifteenth power tube is connected with the first branch, the second end of the fifteenth power tube is connected with the first end of the inductor, the second end of the inductor is connected with the first end of the eighteenth power tube, and the second end of the eighteenth power tube is connected with the second branch.

12. The switched capacitor converter of claim 9, wherein, The fifteenth power tube, the sixteenth power tube, the seventeenth power tube and the eighteenth power tube are N-type power tubes. Alternatively, the fifteenth power tube and the eighteenth power tube are P-type power tubes, and the sixteenth power tube and the seventeenth power tube are N-type power tubes.

13. The switched capacitor converter of claim 10, wherein, The fifteenth power tube and the eighteenth power tube are N-type power tubes or P-type power tubes.

14. The switched capacitor converter of claim 11, wherein, The fifteenth power tube and the eighteenth power tube are N-type power tubes or P-type power tubes.

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