High-power-density resonant switched capacitor converter based on coupled inductor current sharing

Abstract

The invention discloses a high-power-density resonant switched capacitor converter based on coupled inductor current sharing, and relates to the technical field of DC-DC converters, and a DC voltage source in the converter is used for providing input voltage for the high-power-density current sharing resonant switched capacitor converter; the main power tube, the resonant capacitor, the clamping capacitor and the coupling inductor jointly form a resonant network, and the resonant network is used for realizing energy transmission and conversion in the high-power-density current-sharing resonant switched capacitor converter; the coupling inductor realizes a current sharing function through a mutual inductance effect; the resonant capacitor adopts a II-type ceramic capacitor; the synchronous rectification power tube is used for converting energy transmitted by the resonance network into output electric energy; and the filtering output circuit comprises a filtering capacitor and a load and is used for carrying out smooth filtering on the converted output electric energy. According to the invention, the problem of non-uniform current of the resonance branch caused by inconsistent capacitance values of the II-type ceramic capacitors can be suppressed.

Description

Technical Field

[0001] The present application relates to the technical field of DC-DC converters, and in particular to a high power density resonant switched capacitor converter based on coupled inductor current sharing. Background Art

[0002] A resonant switched-capacitor converter utilizes the principles of resonance and switched-capacitor technology to achieve power conversion. It boasts high efficiency, high power density, and modularity, making it suitable as a pre-stage 48V-to-12V converter in a 48V architecture. Resonant switched-capacitor converters often use multilayer ceramic capacitors as resonant capacitors.

[0003] Depending on the material of multilayer ceramic capacitors, they can be divided into Class I ceramic capacitors and Class II ceramic capacitors. The material used for Class I ceramic capacitors has a small dielectric constant and low capacitance, but its electrical properties are very stable and hardly change with temperature or voltage. Therefore, if the converter uses a low-capacitance Class I ceramic capacitor as a resonant capacitor, it will cause large voltage fluctuations at both ends of the capacitor. When the resonant voltage fluctuations at both ends of the capacitor are too large, backflow power will be generated, affecting the overall efficiency of the converter and limiting the power density of the converter. The material used for Class II ceramic capacitors has a large dielectric constant and high capacitance, thereby improving the power density of the resonant switching capacitor converter. However, the electrical properties of Class II ceramic capacitors will vary significantly with temperature and terminal voltage. Due to the inconsistency of the voltages of the resonant capacitors in the resonant switching capacitor converter, when Class II ceramic capacitors are used as resonant capacitors, the actual capacitance will deviate, causing the resonant frequencies of the resonant branches to be inconsistent, resulting in the problem of uneven current in the resonant branches. Summary of the Invention

[0004] The purpose of this application is to provide a high-power density resonant switched capacitor converter based on coupled inductor current sharing. By adopting Class II ceramic capacitors as their resonant capacitors, the power density of the converter is further improved. At the same time, coupled inductors are used as their resonant inductors to suppress the uneven current sharing problem in the resonant branch caused by inconsistent capacitance values ​​of Class II ceramic capacitors.

[0005] To achieve the above objectives, this application provides the following solutions: In a first aspect, the present application provides a high power density resonant switched capacitor converter based on coupled inductor current sharing, comprising: DC voltage source, main power tube, resonant capacitor, clamping capacitor, coupled inductor, synchronous rectifier power tube and filter output circuit.

[0006] The DC voltage source is used to provide an input voltage for a high power density current sharing resonant switched capacitor converter.

[0007] The main power tube, resonant capacitor, clamping capacitor and coupled inductor together form a resonant network for realizing energy transfer and conversion in a high power density current-sharing resonant switched capacitor converter; the resonant capacitor adopts a Class II ceramic capacitor.

[0008] The coupled inductor realizes the current sharing function through the mutual inductance effect.

[0009] The synchronous rectifier power tube is used to convert the energy transmitted by the resonant network into output electrical energy.

[0010] The filter output circuit includes a filter capacitor and a load, and is used to smooth and filter the converted output electric energy.

[0011] Optionally, the main power tube includes a first power tube S 1. Second power tube S 2. The third power tube S 3. The fourth power tube S 4. Fifth power tube S 5 and 6 power tubes S 6; The resonant capacitor includes a first resonant capacitor C r1 , the second resonant capacitor C r2 , the third resonant capacitor C r3 ; The clamping capacitor is composed of a first clamping capacitor C f1 and the second clamping capacitor C f2 Composition; the coupled inductor includes a first resonant inductor L cr1 , the second resonant inductor L cr2 , the third resonant inductor L cr3 、The mutual inductance of the first and second resonant inductors M 12 , the first three resonant inductor mutual inductance value M 13 And the second and third resonant inductance mutual inductance M 23 The synchronous rectifier power tube includes a first synchronous rectifier power tube S 7. Second synchronous rectifier power tube S 8. The third synchronous rectifier power tube S 9. The fourth synchronous rectifier power tube S 10 , the fifth synchronous rectifier power tube S 11 And the sixth synchronous rectifier power tube S 12 .

[0012] Optionally, the first power tube S 1. Second power tube S 2. The third power tube S 3. The fourth power tube S 4. Fifth power tube S 5 and 6 power tubes S 6 are respectively provided with a first anti-parallel diode D 1. Second anti-parallel diode D 2. The third anti-parallel diode D 3. The fourth anti-parallel diode D 4. Fifth anti-parallel diode D 5 and the sixth anti-parallel diode D 6, and the first junction capacitance C 1. Second junction capacitance C 2. Third junction capacitance C 3. Fourth junction capacitance C 4. Fifth junction capacitance C 5 and the sixth junction capacitance C 6.

[0013] Optionally, the first synchronous rectifier power tube S 7. Second synchronous rectifier power tube S 8. The third synchronous rectifier power tube S 9. The fourth synchronous rectifier power tube S 10 , the fifth synchronous rectifier power tube S 11 And the sixth synchronous rectifier power tube S 12 A seventh anti-parallel diode is provided on each D 7. Eighth anti-parallel diode D 8. Ninth anti-parallel diode D 9. The tenth anti-parallel diode D 10 、The eleventh anti-parallel diode D 11 , the twelfth anti-parallel diode D 12 , and the seventh junction capacitance C 7. Eighth junction capacitance C 8. Ninth junction capacitance C 9. Tenth junction capacitance C 10 、Eleventh junction capacitance C 11 and the twelfth junction capacitance C 12 .

[0014] Optionally, the DC voltage sourceV in The positive electrode and the first power tube S 1 is connected to the drain of the first power tube S 1 source and the first resonant capacitor C r1 The upper end is connected to the second power tube S 2 drain, first resonant capacitor C r1 The lower end and the coupled inductor L 1. The first resonant inductor L cr1 The upper end is connected to the second power tube S 2 source and the first clamp capacitor C f1 The upper end is connected to the third power tube S 3 drain, first clamp capacitor C f1 The lower end is connected to a DC voltage source V in The negative pole of the third power tube S 3 source and the second resonant capacitor C r2 The upper end of the fourth power tube is connected to the S 4 drain, the second resonant capacitor C r2 The lower end and the coupled inductor L 1 second resonant inductor L cr2 The upper end is connected to the fourth power tube S 4 source and the second clamp capacitor C f2 The upper end is connected to the fifth power tube S 5 drain, the second clamp capacitor C f2 The lower end is connected to a DC voltage source V in The negative pole of the fifth power tube S 5 source and the third resonant capacitor C r3 The upper end of the sixth power tube is connected to the S 6 drain, the third resonant capacitor C r3 The lower end and the coupled inductor L 1 third resonant inductor L cr3 The upper end is connected to the coupled inductor L 1. The first resonant inductor L cr1 The lower end and the first synchronous rectifier power tube S The drain of 7 is connected to the second synchronous rectifier power tubeS 8 source, coupled inductor L 1 second resonant inductor L cr2 The lower end and the third synchronous rectifier power tube S The drain of 9 is connected to the fourth synchronous rectifier power tube S 10 The source of the coupled inductor L 1 third resonant inductor L cr3 The lower end and the fifth synchronous rectifier power tube S 11 The drains of the six synchronous rectifier power tubes are connected together. S 12 The source of the first synchronous rectifier power tube S 7. The third synchronous rectifier power tube S 9. Fifth synchronous rectifier power tube S 11 The source of the V in The negative pole of the second synchronous rectifier power tube S 8. The fourth synchronous rectifier power tube S 10 , the sixth synchronous rectifier power tube S 12 The drain of the sixth power tube S 6 source, filter capacitor C o The upper end of the load is connected to the R L The upper end of the filter capacitor C o and load R L The lower ends of the two terminals are connected to a DC voltage source. V in of the negative electrode.

[0015] Optionally, the first power tube S 1. The third power tube S 3 and the first power tube S 5 drive signal and the second power tube S 2. The fourth power tube S 4 and the sixth power tube S The driving signal of 6 is a pair of complementary square wave signals with a phase difference of 180 degrees and a duty cycle of 0.5; there is a dead time between the two complementary square wave signals; the first power tube S 1. Second power tube S 2. The third power tube S 3. The fourth power tube S 4. Fifth power tube S5 and 6 power tubes S 6 is used to achieve zero current switching and zero current switching; the first power tube S 1. Second power tube S 2. The third power tube S 3. The fourth power tube S 4. Fifth power tube S 5 and 6 power tubes S The voltage stress of 6 is equal to the output voltage.

[0016] Optionally, the coupled inductor L 1. The mutual inductance of the first and second resonant inductors M 12 , the first three resonant inductor mutual inductance value M 13 And the second and third resonant inductance mutual inductance M 23 are all negative; the first resonant inductor L cr1 , the second resonant inductor L cr2 and the third resonant inductor L cr3 There is reverse coupling between the two.

[0017] Optionally, the coupled inductor L 1. Using a flat design of reverse partially coupled core structure; the coupled inductor L The three windings of 1 are wound on the three magnetic columns of the magnetic core respectively. Each winding is wound on each magnetic column along the same direction by the wiring of the multi-layer PCB board. There is an air gap in the magnetic column. Optionally, the first synchronous rectifier power tube S 7. Second synchronous rectifier power tube S 8. The third synchronous rectifier power tube S 9. The fourth synchronous rectifier power tube S 10 , the fifth synchronous rectifier power tube S 11 And the sixth synchronous rectifier power tube S 12 Used to achieve zero voltage turn-on and zero current turn-off; the first synchronous rectifier power tube S 7. Second synchronous rectifier power tube S 8. The third synchronous rectifier power tube S 9. The fourth synchronous rectifier power tube S 10 , the fifth synchronous rectifier power tube S 11 And the sixth synchronous rectifier power tube S 12 The voltage stress is equal to the output voltage.

[0018] Optionally, the first resonant capacitor C r1 , the second resonant capacitor C r2 , the third resonant capacitor C r3 The DC voltage bias is 3 times the output voltage, 2 times the output voltage, and 1 times the output voltage respectively; the first clamping capacitor C f1 and the second clamping capacitor C f2 The clamping voltage is 3 times the output voltage and 2 times the output voltage respectively.

[0019] According to the specific embodiments provided in this application, this application discloses the following technical effects: The present application provides a high power density resonant switched capacitor converter based on coupled inductor current sharing, comprising: a DC voltage source, a main power tube, a resonant capacitor, a clamping capacitor, a coupled inductor, a synchronous rectifier power tube and a filter output circuit; the DC voltage source is used to provide an input voltage for the high power density current sharing resonant switched capacitor converter; the main power tube and the resonant capacitor, the clamping capacitor and the coupled inductor together constitute a resonant network for realizing the transfer and conversion of energy in the high power density current sharing resonant switched capacitor converter; the resonant capacitor adopts a Class II ceramic capacitor; the coupled inductor realizes the current sharing function through the mutual inductance effect; the synchronous rectifier power tube is used to convert the energy transferred by the resonant network into output electrical energy; the filter output circuit includes a filter capacitor and a load for smoothing and filtering the converted output electrical energy. The present application further improves the power density of the converter by adopting a Class II ceramic capacitor as its resonant capacitor. At the same time, a coupled inductor is used as its resonant inductor to suppress the problem of uneven current in the resonant branch caused by inconsistent capacitance values ​​of the Class II ceramic capacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 This is the circuit diagram of a traditional resonant switched capacitor converter without coupled inductor.

[0022] Figure 2 This is the experimental waveform of the resonant current of the traditional resonant switched capacitor converter without coupled inductor.

[0023] Figure 3A circuit diagram of a high power density resonant switched capacitor converter based on coupled inductor current sharing provided in one embodiment of the present application.

[0024] Figure 4 A schematic diagram of the winding of a three-winding reverse-coupled inductor L1 provided in an embodiment of the present application.

[0025] Figure 5 A schematic diagram of the magnetic circuit of the coupled inductor L1 provided in one embodiment of the present application.

[0026] Figure 6 Schematic diagram of an equivalent model of a coupled inductor L1 and an equivalent model of a coupled inductor with a resonant capacitor provided in one embodiment of the present application.

[0027] Figure 7 Schematic diagram of differential-mode resonant current and common-mode resonant current of an equivalent model of a coupled inductor with a resonant capacitor provided in one embodiment of the present application.

[0028] Figure 8 This is a schematic diagram of a simplified equivalent model provided by an embodiment of the present application in which the magnetizing inductance Lm is neglected.

[0029] Figure 9 A schematic diagram of the differential mode current flow under an independent resonant inductor provided in one embodiment of the present application.

[0030] Figure 10 A schematic diagram of the differential mode current flow under coupled inductor decoupling provided in an embodiment of the present application.

[0031] Figure 11 A schematic diagram of a curve showing a change in the differential mode current rejection ratio (DMCRR) with the coupling coefficient k provided in an embodiment of the present application.

[0032] Figure 12 This is a schematic diagram of the main waveforms of a high power density resonant switched capacitor converter based on coupled inductor current sharing provided in one embodiment of the present application.

[0033] Figure 13 Schematic diagram of switching mode 2 of a high power density resonant switched capacitor converter based on coupled inductor current sharing provided by an embodiment of the present application.

[0034] Figure 14 Schematic diagram of switching mode 5 of a high power density resonant switched capacitor converter based on coupled inductor current sharing provided in one embodiment of the present application.

[0035] Figure 15 This is a resonant current experimental waveform diagram of a high power density resonant switched capacitor converter based on coupled inductor current sharing provided in one embodiment of the present application. Description of the drawings: 1-DC voltage source, 2-main power tube, 3-resonant capacitor, 4-clamping capacitor, 5-coupled inductor, 6-synchronous rectifier power tube, 7-filter output circuit. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0038] With the rapid development of communication technology, artificial intelligence, and information technology, the demand for data storage capacity and computing performance is increasing. As important facilities for high-performance computing and massive data storage, various data centers are growing in size, number, and power consumption. The traditional 12V busbar architecture carries a large current and has high line losses. The 48V busbar architecture is gaining increasing attention because it carries only 1 / 4 of the current of the 12V busbar and has lower line losses. Under the 48V busbar architecture, the two-stage structure (48V-12V-1V) has higher current output capacity and control bandwidth. Therefore, in practical applications, the two-stage structure is often used. The intermediate level can simultaneously power other equipment in the rack, providing greater flexibility.

[0039] Front-end 48V-12V converter topologies can be categorized into two types: isolated and non-isolated. Isolated converters often use LLC resonant converters. However, the large transformer size limits the LLC resonant converter's power density and increases design complexity. In contrast, non-isolated converters, because they lack a bulky transformer, significantly improve power density and are therefore widely used in front-end architectures in data centers.

[0040] like Figure 1 In the conventional resonant switched capacitor converter circuit diagram without coupled inductor shown in FIG, each resonant branch uses a Class II ceramic capacitor as the resonant capacitor C r1 ~ C r3 , use independent small inductor L r1 ~ L r3 as a resonant inductor.

[0041] like Figure 2The resonant current experimental waveforms of a conventional resonant switched capacitor converter without a coupled inductor (see figure) show that the resonant frequencies and resonant current peaks of the three resonant branches are inconsistent, with the peak resonant currents being 13.08A, 11.60A, and 10.30A, respectively. Therefore, the three resonant branches of a conventional resonant switched capacitor converter without a coupled inductor exhibit uneven current distribution. This leads to inconsistent current stress across components, necessitating the selection of component models with greater margins, which increases production costs.

[0042] The purpose of this application is to provide a high-power density resonant switched capacitor converter based on coupled inductor current sharing. By adopting Class II ceramic capacitors as its resonant capacitors 3, the power density of the converter is further improved. At the same time, coupled inductors 5 are used as its resonant inductors to suppress the uneven current sharing problem in the resonant branch caused by inconsistent capacitance values ​​of Class II ceramic capacitors.

[0043] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0044] like Figure 3 As shown, this embodiment provides a high power density resonant switched capacitor converter based on coupled inductor current sharing, including: DC voltage source 1, main power tube 2, resonant capacitor 3, clamping capacitor 4, coupled inductor 5, synchronous rectifier power tube 6 and filter output circuit 7.

[0045] The DC voltage source 1 is used to provide input voltage for a high power density current sharing resonant switched capacitor converter.

[0046] The main power tube 2, the resonant capacitor 3, the clamping capacitor 4 and the coupled inductor 5 together form a resonant network for realizing the transfer and conversion of energy in the high power density current-sharing resonant switched capacitor converter; the resonant capacitor 3 adopts a Class II ceramic capacitor.

[0047] The coupled inductor 5 realizes the current sharing function through the mutual inductance effect.

[0048] The synchronous rectifier power tube 6 is used to convert the energy transmitted by the resonant network into output electrical energy.

[0049] The filter output circuit 7 includes a filter capacitor and a load, and is used to smooth and filter the converted output electrical energy.

[0050] Among them, such as Figure 3 As shown, the main power tube 2 includes a first power tube S 1. Second power tube S 2. The third power tube S 3. The fourth power tube S 4. Fifth power tubeS 5 and 6 power tubes S 6; The resonant capacitor 3 includes a first resonant capacitor C r1 , the second resonant capacitor C r2 , the third resonant capacitor C r3 The clamping capacitor 4 is composed of the first clamping capacitor C f1 and the second clamping capacitor C f2 The coupled inductor 5 includes a first resonant inductor L cr1 , the second resonant inductor L cr2 , the third resonant inductor L cr3 、The mutual inductance of the first and second resonant inductors M 12 , the first three resonant inductor mutual inductance value M 13 And the second and third resonant inductance mutual inductance M 23 The synchronous rectifier power tube 6 includes a first synchronous rectifier power tube S 7. Second synchronous rectifier power tube S 8. The third synchronous rectifier power tube S 9. The fourth synchronous rectifier power tube S 10 , the fifth synchronous rectifier power tube S 11 And the sixth synchronous rectifier power tube S 12 .

[0051] Specifically, the first power tube S 1. Second power tube S 2. The third power tube S 3. The fourth power tube S 4. Fifth power tube S 5 and 6 power tubes S 6 are respectively provided with a first anti-parallel diode D 1. Second anti-parallel diode D 2. The third anti-parallel diode D 3. The fourth anti-parallel diode D 4. Fifth anti-parallel diode D 5 and the sixth anti-parallel diode D 6, and the first junction capacitance C 1. Second junction capacitance C 2. Third junction capacitance C 3. Fourth junction capacitanceC 4. Fifth junction capacitance C 5 and the sixth junction capacitance C 6.

[0052] Specifically, the first synchronous rectifier power tube S 7. Second synchronous rectifier power tube S 8. The third synchronous rectifier power tube S 9. The fourth synchronous rectifier power tube S 10 , the fifth synchronous rectifier power tube S 11 And the sixth synchronous rectifier power tube S 12 A seventh anti-parallel diode is provided on each D 7. Eighth anti-parallel diode D 8. Ninth anti-parallel diode D 9. The tenth anti-parallel diode D 10 、The eleventh anti-parallel diode D 11 , the twelfth anti-parallel diode D 12 , and the seventh junction capacitance C 7. Eighth junction capacitance C 8. Ninth junction capacitance C 9. Tenth junction capacitance C 10 、Eleventh junction capacitance C 11 and the twelfth junction capacitance C 12 .

[0053] The circuit connection relationship of the high power density current sharing resonant switched capacitor converter is as follows: the DC voltage source V in The positive electrode and the first power tube S 1 is connected to the drain of the first power tube S 1 source and the first resonant capacitor C r1 The upper end is connected to the second power tube S 2 drain, first resonant capacitor C r1 The lower end and the coupled inductor L 1. The first resonant inductor L cr1 The upper end is connected to the second power tube S 2 source and the first clamp capacitor C f1 The upper end is connected to the third power tube S 3 drain, first clamp capacitor Cf1 The lower end is connected to a DC voltage source V in The negative pole of the third power tube S 3 source and the second resonant capacitor C r2 The upper end of the fourth power tube is connected to the S 4 drain, the second resonant capacitor C r2 The lower end and the coupled inductor L 1 second resonant inductor L cr2 The upper end is connected to the fourth power tube S 4 source and the second clamp capacitor C f2 The upper end is connected to the fifth power tube S 5 drain, the second clamp capacitor C f2 The lower end is connected to a DC voltage source V in The negative pole of the fifth power tube S 5 source and the third resonant capacitor C r3 The upper end of the sixth power tube is connected to the S 6 drain, the third resonant capacitor C r3 The lower end and the coupled inductor L 1 third resonant inductor L cr3 The upper end is connected to the coupled inductor L 1. The first resonant inductor L cr1 The lower end and the first synchronous rectifier power tube S The drain of 7 is connected to the second synchronous rectifier power tube S 8 source, coupled inductor L 1 second resonant inductor L cr2 The lower end and the third synchronous rectifier power tube S The drain of 9 is connected to the fourth synchronous rectifier power tube S 10 The source of the coupled inductor L 1 third resonant inductor L cr3 The lower end and the fifth synchronous rectifier power tube S 11 The drains of the six synchronous rectifier power tubes are connected together. S 12 The source of the first synchronous rectifier power tube S 7. The third synchronous rectifier power tube S 9. Fifth synchronous rectifier power tube S11 The source of the V in The negative pole of the second synchronous rectifier power tube S 8. The fourth synchronous rectifier power tube S 10 , the sixth synchronous rectifier power tube S 12 The drain of the sixth power tube S 6 source, filter capacitor C o The upper end of the load is connected to the R L The upper end of the filter capacitor C o and load R L The lower ends of the two terminals are connected to a DC voltage source. V in of the negative electrode.

[0054] In this embodiment, based on the high power density resonant switched capacitor converter with coupled inductor current sharing, the first, second, third, fourth, fifth and sixth power transistors are connected to the MOSFET. S 1~ S The PWM drive signal of 6 is: the first power tube S 1. The third power tube S 3 and the first power tube S 5 drive signal and the second power tube S 2. The fourth power tube S 4 and the sixth power tube S The driving signal of 6 is a pair of complementary square wave signals with a phase difference of 180 degrees and a duty cycle of 0.5. A certain dead time needs to be added between the two complementary square wave signals to prevent the generation of current spikes.

[0055] The first, second and third resonant capacitors mentioned in this embodiment are C r1 、 C r2 、 C r3 Use Class II ceramic capacitors. Coupled inductors L 1. The mutual inductance of the first and second resonant inductors M 12 , the mutual inductance of the first and third resonant inductors M 13 And the mutual inductance of the second and third resonant inductors M 23 are all negative, which means the first resonant inductor L cr1 , the second resonant inductor L cr2, the third resonant inductor L cr3 There is a reverse coupling state between the two. L 1 to achieve the current sharing effect of the three branches. Only the first resonant capacitor C r1 By testing the resonant cavity where it is located, the first, second, third, fourth, fifth and sixth synchronous rectifier power tubes can be realized. S 7 ~S 12 Zero current shutdown. Resonant capacitor C r1 ~C r3 The DC voltage bias is 3 times the output voltage, 2 times the output voltage, and 1 times the output voltage respectively; the clamping capacitor C f1 、 C f2 The clamping voltage is 3 times the output voltage and 2 times the output voltage respectively.

[0056] Among them, the first power tube S 1. Second power tube S 2. The third power tube S 3. The fourth power tube S 4. Fifth power tube S 5 and 6 power tubes S 6 is used to achieve zero current switching and zero current switching; the first power tube S 1. Second power tube S 2. The third power tube S 3. The fourth power tube S 4. Fifth power tube S 5 and 6 power tubes S The voltage stress of 6 is equal to the output voltage.

[0057] Among them, the first synchronous rectifier power tube S 7. Second synchronous rectifier power tube S 8. The third synchronous rectifier power tube S 9. The fourth synchronous rectifier power tube S 10 , the fifth synchronous rectifier power tube S 11 And the sixth synchronous rectifier power tube S 12 Used to achieve zero voltage turn-on and zero current turn-off; the first synchronous rectifier power tube S 7. Second synchronous rectifier power tube S 8. The third synchronous rectifier power tube S 9. The fourth synchronous rectifier power tube S 10, the fifth synchronous rectifier power tube S 11 And the sixth synchronous rectifier power tube S 12 The voltage stress is equal to the output voltage.

[0058] Specifically, the first, second, third, fourth, fifth, and sixth synchronous rectifier power tubes described in this embodiment S 7~ S 12 Play the role of synchronous rectification, the second, fourth and sixth synchronous rectification power tubes S 8. S 10 、 S 12 The rising edge of the PWM drive signal is controlled by the first, third and fifth power tubes. S 1. S 3. S 5. The rising edge of the driving signal determines the second, fourth and sixth synchronous rectifier power tubes. S 8. S 10 、 S 12 The falling edge of the PWM drive signal is determined by the current zero crossing point. The first, third and fifth synchronous rectifier power tubes S 7. S 9. S 11 The rising edge of the PWM drive signal is controlled by the second, fourth and sixth power tubes. S 2. S 4. S 6 The rising edge of the driving signal determines the first, third and fifth synchronous rectifier power tubes S 7. S 9. S 11 The falling edge of the PWM drive signal is determined by the current zero crossing point on it. The second, fourth and sixth synchronous rectifier power tubes S 8. S 10 、 S 12 The rising edge of the PWM drive signal is connected to the first, third and fifth power tubes S 1. S 3. S 5. Add a certain delay time between the rising edges of the driving signal to realize the second, fourth and sixth synchronous rectifier power tubes S 8. S 10 、 S 12 Zero voltage turn-on, the first, third and fifth synchronous rectifier power tubes S 7.S 9. S 11 The rising edge of the PWM drive signal and the second, fourth and sixth power tubes S 2. S 4. S 6. Add a certain delay time between the rising edges of the driving signal to realize the first, third and fifth synchronous rectifier power tubes S 7. S 9. S 11 Zero voltage turn-on.

[0059] Among them, Figure 3 The coupled inductor shown L 1. Write the equations for the voltage and current of each winding.

[0060] (1).

[0061] Where, v 1. v 2. v 3 are the voltages of the three windings respectively, i Cr1 、 i Cr2 、 i Cr3 are the currents of the three windings respectively.

[0062] Specific as Figure 4 As shown, the coupled inductor L 1. This design utilizes a flat, partially coupled reverse core structure. Three windings are wound around the three magnetic pillars of the core. Each winding is wound around each pillar in the same direction using multi-layer PCB traces. A certain air gap is left between each pillar to achieve a weak coupling effect. An air gap is typically created within the core. Specifically, a core air gap refers to a portion of the core composed of air. This air gap is simply referred to as an air gap. This air gap is created by intentionally removing a portion of material from the magnetic ring or core.

[0063] like Figure 5 As shown, is the magnetic resistance of the air gap of each winding magnetic column. is the window magnetoresistance caused by the window effect, and the magnetoresistance of each window is simply recorded as 2 .

[0064] Assuming that the three magnetic circuit structures are completely symmetrical, there is self-inductance L cr1 = L cr2 = L cr3 = L , mutual inductionM 12 = M 23 = M 13 = M ,Depend on Figure 5 The magnetic circuit shown can obtain the coupled inductance L 1's self-sensitivity L for: (2).

[0065] Where, N is the number of turns of each winding of the coupled inductor.

[0066] Among them, the coupled inductor L Mutual inductance of 1 M for: (3).

[0067] Substituting equations (2) and (3) into equation (1), we can obtain the relationship between the voltage and current of each winding: (4).

[0068] Where v1, v2, and v3 are the voltages of the three windings respectively.

[0069] in, Figure 6 is the coupled inductance drawn based on formula (4) L 1 equivalent model and its schematic diagram of connection with resonant capacitor. Can be regarded as the excitation inductance L m , 1 / Can be regarded as equivalent series inductance L s .

[0070] From formula (2) and formula (3), we can know that L m and L s for: (5).

[0071] (6).

[0072] In formula (6), k is the coupling coefficient, M is the mutual inductance of the coupled inductor. When the coupling coefficient is -1 / 2, L m / L s Will tend to infinity, at this time the excitation inductance L mThe current flowing is very small.

[0073] Figure 7 To resonate the capacitor C r1 、 C r2 、 C r3 Schematic diagram of the equivalent model after equivalent transformation to the secondary side. C r1s 、 C r2s 、 C r3s is the equivalent resonant capacitor transformed to the secondary side. The common-mode resonant current flowing through this equivalent model is i CM , the differential mode resonant current is i DM1 、 i DM2 and i DM3 Among them, the secondary current of the equivalent model is: (7).

[0074] like Figure 7 As shown, when the excitation inductance L m When it is very large, the differential mode resonant current i DM1 、 i DM2 and i DM3 Very small.

[0075] in, Figure 8 To ignore the excitation inductance L m A simplified equivalent model diagram is shown. In this model, the differential-mode current is set to zero, meaning there is no current difference between the two windings. Only common-mode current exists. Common-mode current refers to current flowing in the same direction and with equal magnitude through both windings. This setting allows the coupled inductor to achieve current sharing, ensuring a balanced current flow through each winding, thereby improving system stability and efficiency.

[0076] Figure 9 is the differential mode current flow diagram under independent resonant inductance. The time domain expression of the differential mode current between any two resonant cavities (x phase and y phase) is: (8).

[0077] Where, V Cx 、 V Crx_minare the clamping capacitance in the x-phase resonant cavity branch C x DC voltage, resonant capacitance C rx The minimum voltage, V Cy 、 V Cry_min are the clamping capacitance in the y-phase resonant cavity branch C y DC voltage, resonant capacitance C ry The minimum voltage, L r is an independent resonant inductor, C xy is the equivalent series resonant capacitance of the differential mode current loop.

[0078] (9).

[0079] Among them, the peak value of differential mode current is: (10).

[0080] Figure 10 This is the differential mode current flow diagram under coupled inductor decoupling. The differential mode current time domain expression is: (11).

[0081] Among them, the peak value of differential mode current is: (12).

[0082] Differential Mode Current Rejection Ratio DMCRR )for: (13).

[0083] Substituting equations (10) and (12) into equation (13), we can obtain the differential mode current suppression ratio ( DMCRR ) The specific calculation formula is: (14).

[0084] in, M = kL , L r = L +2 M .

[0085] in, Figure 11 is the differential mode current rejection ratio ( DMCRR ) with the coupling coefficient kThe changing curve, such as Figure 11 As shown, when the coupling coefficient k As the value gradually changes towards -1 / 2, DMCRR The differential-mode current rejection ratio (DMCRR) shows a rapid increase. Specifically, the DMCRR value can be significantly improved to approximately 35dB. This change significantly enhances the system's ability to suppress differential-mode current, resulting in superior performance in terms of electromagnetic compatibility and signal integrity. This adjustment effectively reduces interference caused by differential-mode current and improves system stability and reliability.

[0086] In this application, Figure 3 As the main circuit structure, combined with Figures 12 to 14 The specific working principle of the high power density resonant switched capacitor converter based on coupled inductor current sharing proposed in this embodiment is discussed in detail. Figure 12 It can be seen that the converter can be divided into the first and second half cycles in one switching cycle, with a total of 6 sub-modes, namely [ t 0~ t 1]、[ t 1~ t 2]、[ t 2~ t 3]、[ t 3~ t 4]、[ t 4~ t 5]、[ t 5~ t 6].

[0087] For the convenience of analysis, we first make the following assumptions: 1) The first, second, third, fourth, fifth, and sixth power tubes S 1~ S 6 and the first, second, third, fourth, fifth, and sixth synchronous rectifier power tubes S 7~ S 12 It is an ideal device with zero on-state voltage drop; 2) Clamping capacitor C f1 、 C f2 and output filter capacitors C o Large enough, the corresponding voltage can be regarded as a constant voltage source; 3) The first, second, third, fourth, fifth, and sixth power tubes S 1~ S The junction capacitances of 6 are equal and are C 1= C 2= C 3= C 4= C 5= C 6= CDS1 ; 4) The first, second, third, fourth, fifth and sixth synchronous rectifier power tubes S 7~ S 12 The junction capacitances are equal and are C 7= C 8= C 9= C 10 = C 11 = C 12 = C DS2 5) Coupled inductor L 1's mutual inductance values ​​are equal and M 12 = M 23 = M 13 = M ( M <0).

[0088] Switch mode 1[ t 0~ t 1]: exist t 0~ t 1st stage, first, second, third, fourth, fifth, sixth power tubes S 1~ S 6 are all turned off, the resonant capacitor current i Cr1 ~ i Cr3 All are 0, the first, second, third, fourth, fifth, and sixth synchronous rectifier power tubes S 7~ S 12 cut-off, the load power is supplied by the output capacitor C o In this mode, the resonant capacitor voltage no longer changes and remains at a constant value. The first, third, and fifth power tubes S 1. S 3. S 5 Withstand voltage stress v DS1 、 v DS3 、 v DS5 equal U o .

[0089] Switch Mode 2[ t 1~ t 2]: like Figure 13 As shown, t= t 1 moment, the first, third and fifth power tubes S 1. S 3. S 5 is turned on. Since the current of the previous modal resonant capacitor is zero, the first, third and fifth power tubes S 1. S 3 、S 5 is zero current conduction. In this mode, the resonant capacitor resonates with the resonant inductor, and the resonant current increases from zero to the maximum value and then begins to decrease until t At moment 2, the resonant current decreases to zero and the resonant capacitor voltage v Cr1 、 v Cr2 、 v Cr3 from t 1 moment and then increases until t 2 reaches the maximum value at the moment. S 1. S 3. S 5 rising edge and the second, fourth and sixth synchronous rectifier power tubes S 8. S 10 、 S 12 There is a certain dead time between the rising edges, so the second, fourth and sixth synchronous rectifier power tubes S 8. S 10 、 S 12 It is zero voltage conduction. Resonant current i Cr1 、 i Cr2 、 i Cr3 The second, fourth and sixth synchronous rectifier power tubes are respectively S 8. S 10 、 S 12 Sent to filter capacitor C o and load R L At this time, the second, fourth and sixth power tubes S 2. S 4. S 6 Withstand voltage stress v DS2 、 v DS4 、 v DS6 equal U o .

[0090] Switch Mode 3[ t 2~ t 3]: t = t At moment 2, the resonant current crosses zero, and the second, fourth, and sixth synchronous rectifier power tubes S 8. S 10 、 S 12 Turn off, so the second, fourth and sixth synchronous rectifier power tubes S 8. S 10 、 S 12 Zero current shutdown.

[0091] exist t 2~ t In the 3rd stage, the resonant capacitor voltage has the following relationship: (15).

[0092] Therefore, in this stage, the resonant capacitor current will not increase or decrease, and will remain constant at zero. The resonant capacitor voltage will also no longer change and will remain at a constant value. The second, fourth, and sixth power tubes S 2. S 4. S 6 Withstand voltage stress v DS2 、 v DS4 、 v DS6 equal U o .

[0093] Switch mode 4[ t 3~ t 4]: t = t 3 moments, the first, third, and fifth power tubes S 1. S 3. S 5 is turned off. Since the current of the previous modal resonant capacitor is zero, the first, third and fifth power tubes S 1. S 3. S 5 is zero current shutdown. In this mode, the voltage and current of the resonant capacitor remain unchanged, and the second, fourth, and sixth power tubes S 2. S 4. S 6 Withstand voltage stress v DS2 、v DS4 、 v DS6 Still equal to U o .

[0094] Switch Mode 5[ t 4~ t 5]: like Figure 14 As shown, t = t 4 moments, the second, fourth, and sixth power tubes S 2. S 4. S 6 is turned on. Since the current of the previous modal resonant capacitor is zero, the second, fourth and sixth power tubes S 2. S 4. S 6 is zero current conduction. In this mode, the resonant capacitor and the resonant inductor resonate, and the resonant current decreases from zero to the minimum value and then begins to increase until t At moment 5, the resonant current increases to zero and the resonant capacitor voltage v Cr1 、 v Cr2 、 v Cr3 from t 4 starts to decrease until t 5 reaches the minimum value at the moment. S 2. S 4. S 6 rising edge and the first, third and fifth synchronous rectifier power tubes S 7. S 9. S 11 There is a certain dead time between the rising edges, so the first, third and fifth synchronous rectifier power tubes S 7. S 9. S 11 It is zero voltage conduction. Resonant current i Cr1 、 i Cr2 、 i Cr3 Respectively through the first, third and fifth synchronous rectifier power tubes S 7. S 9. S 11 Flow into the clamp capacitor C f1 、 C f2 And output circuit, at this time the first, third and fifth power tubesS 1. S 3. S 5 Withstand voltage stress v DS1 、 v DS3 、 v DS5 equal U o .

[0095] Switch mode 6[ t 5~ t 6]: t = t At moment 5, the resonant current crosses zero, and the first, third, and fifth synchronous rectifier power tubes S 7. S 9. S 11 Turn off, so the first, third and fifth synchronous rectifier power tubes S 7. S 9. S 11 Zero current shutdown.

[0096] exist t 5~ t In stage 6, the resonant capacitor voltage has the following relationship: (16).

[0097] Therefore, in this stage, the resonant capacitor current will not increase or decrease, and will remain constant at zero. The resonant capacitor voltage will also no longer change and will remain at a constant value. The first, third, and fifth power tubes S 1. S 3. S 5 Withstand voltage stress V DS for U o . t 6 Moment 2, 4, 6th power tube S 2. S 4. S 6 is turned off. Since the resonant capacitor current is zero before the turn-off, the second, fourth and sixth power tubes S 2. S 4. S 6 is zero current shutdown. So far, the mode discussion within one cycle is completed.

[0098] Figure 14 The resonant current experimental waveform of the high power density resonant switched capacitor converter based on coupled inductor current sharing is proposed for this embodiment. Figure 15As shown, the resonant frequencies and resonant current peaks of the three resonant branches are substantially consistent, with the peak values ​​of the resonant current being 11.25 A, 11.01 A, and 10.69 A, respectively. Therefore, the high power density resonant switched capacitor converter based on coupled inductor current sharing proposed in this embodiment achieves current sharing in the three resonant branches.

[0099] In summary, this application has the following technical effects: 1) The three-winding reverse-coupled inductor proposed in this application utilizes magnetic component flattening technology, combined with highly consistent PCB windings, to achieve a flat coupled inductor. This three-phase coupled inductor design effectively mitigates the potential issues of capacitance deviation caused by inconsistent terminal voltages on Class II ceramic capacitors, as well as current imbalance in the resonant branches caused by inconsistent resonant branch parameters.

[0100] 2) The main technical features of this application compared with the prior art are: the resonant capacitor uses a Class II ceramic capacitor, the resonant inductor is replaced by a coupled inductor, any resonant inductor is reversely coupled with the remaining resonant inductors, the coupled inductor currents are equal in magnitude and direction, and the current sharing effect is achieved. Only the first resonant capacitor needs to be connected. C r1 The first, second, third, fourth, fifth and sixth synchronous rectifier power tubes can be realized by detecting the resonant cavity where they are located. S 7~ S 12 Compared with existing topologies, the invented converter is simple to control, has high output power, and can achieve high-efficiency and high-power density power conversion.

[0101] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A high power density resonant switched capacitor converter based on coupled inductor current sharing, characterized in that: include: DC voltage source, main power tube, resonant capacitor, clamping capacitor, coupled inductor, synchronous rectifier power tube and filter output circuit; The DC voltage source is used to provide an input voltage for the high power density current sharing resonant switched capacitor converter; The main power tube, resonant capacitor, clamping capacitor and coupled inductor together form a resonant network for realizing energy transfer and conversion in a high power density current-sharing resonant switched capacitor converter; the resonant capacitor is a Class II ceramic capacitor; The coupled inductor realizes the current sharing function through the mutual inductance effect; The synchronous rectifier power tube is used to convert the energy transmitted by the resonant network into output electrical energy; The filter output circuit includes a filter capacitor and a load, and is used to smooth and filter the converted output electric energy.

2. The high power density resonant switched capacitor converter based on coupled inductor current sharing according to claim 1, characterized in that: The main power tube includes a first power tube S 1. Second power tube S 2. The third power tube S 3. The fourth power tube S 4. Fifth power tube S 5 and 6 power tubes S 6; The resonant capacitor includes a first resonant capacitor C r1 , the second resonant capacitor C r2 , the third resonant capacitor C r3 ; The clamping capacitor is composed of a first clamping capacitor C f1 and the second clamping capacitor C f2 Composition; the coupled inductor includes a first resonant inductor L cr1 , the second resonant inductor L cr2 , the third resonant inductor L cr3 、The mutual inductance of the first and second resonant inductors M 12 , the first three resonant inductor mutual inductance value M 13 And the second and third resonant inductance mutual inductance M 23 The synchronous rectifier power tube includes a first synchronous rectifier power tube S 7. Second synchronous rectifier power tube S 8. The third synchronous rectifier power tube S 9. The fourth synchronous rectifier power tube S 10 , the fifth synchronous rectifier power tube S 11 And the sixth synchronous rectifier power tube S 12 .

3. The high power density resonant switched capacitor converter based on coupled inductor current sharing according to claim 2, characterized in that: The first power tube S 1. Second power tube S 2. The third power tube S 3. The fourth power tube S 4. Fifth power tube S 5 and 6 power tubes S 6 are respectively provided with a first anti-parallel diode D 1. Second anti-parallel diode D 2. The third anti-parallel diode D 3. The fourth anti-parallel diode D 4. Fifth anti-parallel diode D 5 and the sixth anti-parallel diode D 6, and the first junction capacitance C 1. Second junction capacitance C 2. Third junction capacitance C 3. Fourth junction capacitance C 4. Fifth junction capacitance C 5 and the sixth junction capacitance C 6.

4. The high power density resonant switched capacitor converter based on coupled inductor current sharing according to claim 3, characterized in that: The first synchronous rectifier power tube S 7. Second synchronous rectifier power tube S 8. The third synchronous rectifier power tube S 9. The fourth synchronous rectifier power tube S 10 , the fifth synchronous rectifier power tube S 11 And the sixth synchronous rectifier power tube S 12 A seventh anti-parallel diode is provided on each D 7. Eighth anti-parallel diode D 8. Ninth anti-parallel diode D 9. The tenth anti-parallel diode D 10 、The eleventh anti-parallel diode D 11 , the twelfth anti-parallel diode D 12 , and the seventh junction capacitance C 7. Eighth junction capacitance C 8. Ninth junction capacitance C 9. Tenth junction capacitance C 10 、Eleventh junction capacitance C 11 and the twelfth junction capacitance C 12 .

5. The high power density resonant switched capacitor converter based on coupled inductor current sharing according to claim 4, characterized in that: The DC voltage source V in The positive electrode and the first power tube S 1 is connected to the drain of the first power tube S 1 source and the first resonant capacitor C r1 The upper end is connected to the second power tube S 2 drain, first resonant capacitor C r1 The lower end and the coupled inductor L 1. The first resonant inductor L cr1 The upper end is connected to the second power tube S 2 source and the first clamp capacitor C f1 The upper end is connected to the third power tube S 3 drain, first clamp capacitor C f1 The lower end is connected to a DC voltage source V in The negative pole of the third power tube S 3 source and the second resonant capacitor C r2 The upper end of the fourth power tube is connected to the S 4 drain, the second resonant capacitor C r2 The lower end and the coupled inductor L 1 second resonant inductor L cr2 The upper end is connected to the fourth power tube S 4 source and the second clamp capacitor C f2 The upper end of the fifth power tube is connected to the S 5 drain, the second clamp capacitor C f2 The lower end is connected to a DC voltage source V in The negative pole of the fifth power tube S 5 source and the third resonant capacitor C r3 The upper end of the sixth power tube is connected to the S 6 drain, the third resonant capacitor C r3 The lower end and the coupled inductor L 1 third resonant inductor L cr3 The upper end is connected to the coupled inductor L 1. The first resonant inductor L cr1 The lower end and the first synchronous rectifier power tube S The drain of 7 is connected to the second synchronous rectifier power tube S 8 source, coupled inductor L 1 second resonant inductor L cr2 The lower end and the third synchronous rectifier power tube S The drain of 9 is connected to the fourth synchronous rectifier power tube S 10 The source of the coupled inductor L 1 third resonant inductor L cr3 The lower end and the fifth synchronous rectifier power tube S 11 The drains of the six synchronous rectifier power tubes are connected together. S 12 The source of the first synchronous rectifier power tube S 7. The third synchronous rectifier power tube S 9. Fifth synchronous rectifier power tube S 11 The source of the V in The negative pole of the second synchronous rectifier power tube S 8. The fourth synchronous rectifier power tube S 10 , the sixth synchronous rectifier power tube S 12 The drain of the sixth power tube S 6 source, filter capacitor C o The upper end of the load is connected to the R L The upper end of the filter capacitor C o and load R L The lower ends of the two terminals are connected to a DC voltage source. V in of the negative electrode.

6. The high power density resonant switched capacitor converter based on coupled inductor current sharing according to claim 5, characterized in that: The first power tube S 1. The third power tube S 3 and the first power tube S 5 drive signal and the second power tube S 2. The fourth power tube S 4 and the sixth power tube S The driving signal of 6 is a pair of complementary square wave signals with a phase difference of 180 degrees and a duty cycle of 0.5; there is a dead time between the two complementary square wave signals; the first power tube S 1. Second power tube S 2. The third power tube S 3. The fourth power tube S 4. Fifth power tube S 5 and 6 power tubes S 6 is used to achieve zero current switching and zero current switching; the first power tube S 1. Second power tube S 2. The third power tube S 3. The fourth power tube S 4. Fifth power tube S 5 and 6 power tubes S The voltage stress of 6 is equal to the output voltage.

7. The high power density resonant switched capacitor converter based on coupled inductor current sharing according to claim 6, characterized in that: The coupled inductor L 1. The mutual inductance of the first and second resonant inductors M 12 , the first three resonant inductor mutual inductance value M 13 And the second and third resonant inductance mutual inductance M 23 are all negative; the first resonant inductor L cr1 , the second resonant inductor L cr2 and the third resonant inductor L cr3 There is reverse coupling between the two.

8. The high power density resonant switched capacitor converter based on coupled inductor current sharing according to claim 7, characterized in that: The coupled inductor L 1. Using a flat design of reverse partially coupled core structure; the coupled inductor L The three windings of 1 are respectively wound on the three magnetic columns of the magnetic core, and each winding is wound on each magnetic column along the same direction by the routing of the multi-layer PCB board, and an air gap is provided in each magnetic column.

9. The high power density resonant switched capacitor converter based on coupled inductor current sharing according to claim 8, characterized in that: The first synchronous rectifier power tube S 7. Second synchronous rectifier power tube S 8. The third synchronous rectifier power tube S 9. The fourth synchronous rectifier power tube S 10 , the fifth synchronous rectifier power tube S 11 And the sixth synchronous rectifier power tube S 12 Used to achieve zero voltage turn-on and zero current turn-off; the first synchronous rectifier power tube S 7. Second synchronous rectifier power tube S 8. The third synchronous rectifier power tube S 9. The fourth synchronous rectifier power tube S 10 , the fifth synchronous rectifier power tube S 11 And the sixth synchronous rectifier power tube S 12 The voltage stress is equal to the output voltage.

10. The high power density resonant switched capacitor converter based on coupled inductor current sharing according to claim 9, characterized in that: The first resonant capacitor C r1 , the second resonant capacitor C r2 , the third resonant capacitor C r3 The DC voltage bias is 3 times the output voltage, 2 times the output voltage, and 1 times the output voltage respectively; the first clamping capacitor C f1 and the second clamping capacitor C f2 The clamping voltage is 3 times the output voltage and 2 times the output voltage respectively.

Images