DC-DC Converter DC Output High-Frequency Ripple Suppression Method

Abstract

The present invention proposes a method for suppressing high-frequency ripple in the DC output of a DC-DC converter. Based on a high-frequency ripple suppression circuit for the DC output of a high-frequency DC-DC resonant converter, it includes the DC output terminal of the high-frequency DC-DC resonant converter, a high-frequency ripple suppression circuit, and a load terminal. By using a V-shaped and inverted V-shaped PCB wiring method to cross-parallel connect n filter capacitors, the current directions flowing through every two adjacent capacitors are opposite, so that the parasitic parameters of these n capacitors and the PCB traces form a filter with excellent high-frequency characteristics, ultimately improving the high-frequency ripple suppression ability of the DC output of the high-frequency DC-DC resonant converter; the present invention can be used on the DC output side of a high-frequency DC-DC converter, and has the characteristics of good high-frequency ripple suppression effect, small volume, and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of power converters, and in particular to a high-frequency ripple suppression technology for a high-frequency DC-DC resonant converter, and in particular to a method for suppressing a high-frequency ripple in a DC-DC converter's DC output. Background Art

[0002] In recent years, with the continuous development of science and technology, the market competition for portable electronic devices such as mobile phones and computers is very fierce, and the research on special power supply equipment for aerospace at home and abroad is also hot. Therefore, both consumer electronic products and the industrial sector have a more urgent need for lightweight, high-efficiency and high-reliability power converters. The passive components of the converter, especially the energy storage components (inductors, transformers and capacitors), often occupy a large volume and weight of the entire circuit system. Reducing the volume and weight of passive components can improve the power density of the power circuit. Since increasing the operating frequency of the power converter circuit can reduce the energy transmitted and stored in each switching cycle, thereby obtaining a smaller value of passive components, the switching frequency of the power converter is constantly increasing. However, at a switching operating frequency of several MHz or even up to tens of MHz, the DC-DC converter working in the switching mode, even if the resonant converter circuit is used to take into account efficiency, that is, there are a large number of harmonic transmission processes in the high-frequency DC-DC resonant converter circuit, so there is a large high-frequency ripple on the DC output side of the converter.

[0003] In the prior art, in order to solve the problem of excessive high-frequency ripple on the DC output side, high-frequency DC-DC resonant converters generally use multi-capacitor parallel filters on the DC output side. However, using this method to suppress high-frequency ripple will have the following defects: ① At operating frequencies above several MHz, there is unfavorable near-field coupling between parallel capacitors, which seriously reduces the high-frequency performance of the high-frequency ripple suppression circuit; ② The number of parallel high-frequency capacitors often reaches as many as ten, which has a certain impact on the power density. Summary of the invention

[0004] The present invention provides a method for suppressing high-frequency ripple of a DC-DC converter DC output, which can be used on the DC output side of a high-frequency DC-DC resonant converter and has the advantages of good high-frequency ripple suppression effect, small size, low cost, etc.

[0005] The present invention adopts the following technical solutions.

[0006] DC-DC Converter DC Output High-Frequency Ripple Suppression Method, the method is based on a high-frequency DC-DC resonant converter DC output high-frequency ripple suppression circuit, which includes the DC output terminal Vo1 (1) of the high-frequency DC-DC resonant converter, a high-frequency ripple suppression circuit (2), and a load terminal Vo (3); the filter capacitors of the high-frequency ripple suppression circuit (2) include a first capacitor (C1), a second capacitor (C2),... a nth capacitor (Cn);

[0007] The high-frequency ripple suppression circuit cross-parallels n filter capacitors through V-shaped and inverted V-shaped PCB wiring methods, so that the current directions flowing through every two adjacent capacitors are opposite, so that the parasitic parameters of these n capacitors and the PCB traces form a filter with excellent high-frequency characteristics.

[0008] One end of the first capacitor (C1) is connected to the positive pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter, and the other end of the first capacitor (C1) is connected to the negative pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter; one end of the second capacitor (C2) is connected to one end of the first capacitor (C1) connected to the positive pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter through a PCB trace, and the other end of the second capacitor (C2) is connected to the negative pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter; and so on, one end of the nth capacitor (Cn) is connected to one end of the (n-1)th capacitor (Cn-1) connected to the positive pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter through a PCB trace, and the other end of the nth capacitor (Cn) is connected to the negative pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter; the current directions flowing through every two adjacent capacitors among the n capacitors are opposite; the positive pole of the load terminal Vo is connected to one end of the nth capacitor (Cn) connected to the positive pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter, and the negative pole of the load terminal Vo is connected to the negative pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter.

[0009] One end of the n capacitors connected to the negative pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter is connected by a via.

[0010] In the high-frequency ripple suppression circuit, the PCB traces connecting every three adjacent capacitors adopt V-shaped and inverted V-shaped traces.

[0011] In the high-frequency ripple suppression circuit, the first capacitor (C1), the second capacitor (C2),..., the nth capacitor (Cn) are all filter capacitors. The n filter capacitors are cross-connected in parallel through V-shaped and inverted V-shaped PCB trace patterns. The current directions flowing through every two adjacent capacitors are opposite to each other. The PCB trace connecting the two capacitors is lengthened and forms a 45° angle with the adjacent capacitor, so that the parasitic parameters of the n capacitors and the PCB traces form a filter with excellent high-frequency characteristics. That is, the high-frequency ripple suppression circuit is equivalent to a multi-stage π-type filter, improving the high-frequency ripple suppression ability of the DC output.

[0012] In the equivalent circuit of the multi-stage π-type filter equivalent to the high-frequency ripple suppression circuit, Lc1 to Lcn and Rc1 to Rcn are the equivalent series inductance and equivalent series resistance of capacitors C1 to Cn respectively. Ld1 to Ldn are the equivalent inductances formed by the loops between every two adjacent capacitors. Mc1-Ld1 is the mutual inductance between capacitor C1 and Ld1, Mc1-c2 is the mutual inductance between capacitor C1 and C2, and so on. Mcn-Ldn-1 is the mutual inductance between capacitor Cn and Ldn-1, and Mcn-1-cn is the mutual inductance between capacitor Cn-1 and Cn. Let Ld1 = Ld, Mc1-Ld1 = Mc2-Ld1 = Mcd, and Mc1-c2 = Mc. Then the insertion gain S of voltage Vo with respect to source Vs 21_New is expressed by the formula:

[0013]

[0014] In the formula:

[0015]

[0016] A 2 = ω 2 C(L C -M cd )-1 - jωRC;

[0017]

[0018] where the coupling coefficient k between two capacitors c = M c / L c , and the coupling coefficient between the capacitor and Ld

[0019] The high-frequency ripple suppression circuit can be decoupled from the main circuit of the high-frequency DC-DC resonant converter.

[0020] In the high-frequency ripple suppression circuit, the number of capacitors n is an integer greater than or equal to 2.

[0021] The packaging form of the n capacitors of the high-frequency ripple suppression circuit (2) is surface mount packaging.

[0022] The high-frequency ripple suppression circuit further includes a PCB trace and pads for connecting n capacitors and the PCB trace.

[0023] The high-frequency ripple suppression circuit proposed by the present invention has the characteristics of good high-frequency ripple suppression effect, small volume and low cost, and is particularly suitable for the DC output side of high-frequency DC-DC resonant converters.

[0024] The present invention has the following advantages:

[0025] ①. Most of the adverse near-field couplings existing in the conventional multi-capacitor parallel filter are transformed into favorable near-field couplings, improving the high-frequency performance of the high-frequency ripple suppression circuit, thereby effectively suppressing the high-frequency ripple output at the DC output end of the high-frequency DC-DC resonant converter, and enabling the load end to obtain a DC voltage with fewer high-frequency components.

[0026] ②. Since the PCB wiring method of the high-frequency ripple suppression circuit adopts V-shaped and inverted V-shaped traces and the wiring is relatively compact, the volume of the converter will not be increased.

[0027] ③. Under the condition of achieving the same filtering effect, the number of capacitors in the high-frequency ripple suppression circuit is less than that in the traditional method, which is beneficial to further improving the power density of the high-frequency converter.

[0028] ④. The high-frequency ripple suppression circuit only needs to reasonably design the PCB wiring, and the circuit parameters do not need to be designed in detail, and the error tolerance rate is relatively high.

[0029] ⑤. The high-frequency ripple suppression circuit can be decoupled from the main circuit of the high-frequency DC-DC resonant converter, so the high-frequency ripple suppression circuit will not affect the normal resonant state of the main circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments:

[0031] FIG Figure 1 is a schematic structural diagram of a traditional multi-capacitor parallel filter in the prior art;

[0032] FIG Figure 2 is a schematic diagram of the equivalent circuit of a two-stage model of a traditional multi-capacitor parallel filter;

[0033] FIG Figure 3 is a schematic curve diagram of the insertion gain S21_Tradition of a two-stage model of a traditional multi-capacitor parallel filter varying with the coupling coefficient kc between capacitors;

[0034] FIG Figure 4 is a schematic structural diagram of the high-frequency ripple suppression circuit of the present invention;

[0035] Appendix Figure 5 is a schematic diagram of the equivalent model of the high-frequency ripple suppression circuit of the present invention;

[0036] Appendix Figure 6 is a schematic diagram of the equivalent circuit of the two-stage model of the high-frequency ripple suppression circuit of the present invention;

[0037] Appendix Figure 7 is a schematic diagram of a comparison curve of the insertion gain S21_Tradition of the two-stage model of the traditional multi-capacitor parallel filter and the insertion gain S21_New of the two-stage model of the high-frequency ripple suppression circuit under the same kc;

[0038] Appendix Figure 8 is a schematic diagram of the electrical principle of a preferred embodiment of the high-frequency ripple suppression circuit of the present invention;

[0039] In the figure: 1 - DC output terminal Vo1 of the high-frequency DC-DC resonant converter; 2 - high-frequency ripple suppression circuit; 3 - load terminal Vo;

[0040] 10 - inverter; 20 - matching network; 50 - load; 60 - hysteresis control circuit; 70 - drive circuit. Specific embodiments

[0041] As shown in the figure, a method for suppressing high-frequency ripple at the DC output of a DC-DC converter, the method is based on a high-frequency DC-DC resonant converter DC output high-frequency ripple suppression circuit, which includes a DC output terminal Vo1 (1) of the high-frequency DC-DC resonant converter, a high-frequency ripple suppression circuit (2) and a load terminal Vo (3); the filter capacitors of the high-frequency ripple suppression circuit (2) include a first capacitor (C1), a second capacitor (C2)... an nth capacitor (Cn);

[0042] The high-frequency ripple suppression circuit cross-parallels n filter capacitors through V-shaped and inverted V-shaped PCB wiring methods, so that the current directions of every two adjacent capacitors are opposite, so that these n capacitors and the parasitic parameters of the PCB traces form a filter with excellent high-frequency characteristics;

[0043] One end of the first capacitor (C1) is connected to the positive electrode of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter, and the other end of the first capacitor (C1) is connected to the negative electrode of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter; one end of the second capacitor (C2) is connected to one end of the first capacitor (C1) connected to the positive electrode of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter through a PCB trace, and the other end of the second capacitor (C2) is connected to the negative electrode of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter; and so on, one end of the nth capacitor (Cn) is connected to one end of the (n-1)th capacitor (Cn-1) connected to the positive electrode of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter through a PCB trace, and the other end of the nth capacitor (Cn) is connected to the negative electrode of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter; the current directions flowing through every two adjacent capacitors among the n capacitors are opposite to each other; the positive electrode of the load terminal Vo is connected to one end of the nth capacitor (Cn) connected to the positive electrode of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter, and the negative electrode of the load terminal Vo is connected to the negative electrode of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter.

[0044] One end of the n capacitors connected to the negative electrode of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter is connected by a via.

[0045] In the high-frequency ripple suppression circuit, the PCB traces connecting every three adjacent capacitors adopt V-shaped and inverted V-shaped routing.

[0046] In the high-frequency ripple suppression circuit, the first capacitor (C1), the second capacitor (C2),..., the nth capacitor (Cn) are all filter capacitors. The n filter capacitors are cross-connected in parallel through V-shaped and inverted V-shaped PCB routing methods. The current directions flowing through every two adjacent capacitors are opposite to each other. The PCB trace connecting the two capacitors is lengthened and forms a 45° angle with the adjacent capacitor, so that the parasitic parameters of the n capacitors and the PCB traces form a filter with excellent high-frequency characteristics, that is, the high-frequency ripple suppression circuit is equivalent to a multi-stage π-type filter, improving the high-frequency ripple suppression ability of the DC output.

[0047] In the high-frequency ripple suppression circuit, the specifications of each filter capacitor are the same. The connection between two adjacent filter capacitors is regarded as a two-stage electrical model. In the parallel connection method of the two capacitors, the two-capacitor filter is equivalent to a π-type filter by using the parasitic parameters of the PCB circuit and the capacitor.

[0048] In the equivalent circuit of the multi-stage π-type filter equivalent to the high-frequency ripple suppression circuit, Lc1 to Lcn and Rc1 to Rcn are the equivalent series inductance and equivalent series resistance of capacitors C1 to Cn respectively, Ld1 to Ldn are the equivalent inductances formed by the loops between every two adjacent capacitors, Mc1-Ld1 is the mutual inductance between capacitor C1 and Ld1, Mc1-c2 is the mutual inductance between capacitor C1 and C2, and so on, Mcn-Ldn-1 is the mutual inductance between capacitor Cn and Ldn-1, Mcn-1-cn is the mutual inductance between capacitor Cn-1 and Cn; assuming Ld1 = Ld, Mc1-Ld1 = Mc2-Ld1 = Mcd, Mc1-c2 = Mc, then the insertion gain S of voltage Vo with respect to source Vs 21_New is expressed by the formula as:

[0049]

[0050] In the formula:

[0051]

[0052] A 2 = ω 2 C(L C - M cd ) - 1 - jωRC;

[0053]

[0054] where the coupling coefficient k between two capacitors c = M c / L c , and the coupling coefficient between the capacitor and Ld

[0055] The high-frequency ripple suppression circuit can be decoupled from the main circuit of the high-frequency DC-DC resonant converter.

[0056] In the high-frequency ripple suppression circuit, the number n of capacitors is an integer greater than or equal to 2.

[0057] The packaging form of the n capacitors of the high-frequency ripple suppression circuit (2) is surface mount packaging.

[0058] The high-frequency ripple suppression circuit further includes PCB traces and pads for connecting the n capacitors and the PCB traces.

[0059] Example 1:

[0060] In this example, in combination with the traditional technology, the inventive solution of this example will be described:

[0061] Figure 1The traditional multi-capacitor parallel filter shown. The circuit includes the DC output terminal Vo1 of the high-frequency DC-DC resonant converter, the traditional multi-capacitor filter, and the load terminal Vo; the traditional multi-capacitor filter (2) includes capacitors C1, C2... Cn, PCB traces, and pads connecting the capacitors and the PCB traces; specifically, the input terminal of the filter (2) is connected in parallel to the DC output terminal Vo1 (1) of the high-frequency DC-DC resonant converter, the output terminal of the filter (2) is connected to the load terminal Vo (3), and then the capacitors C1 to Cn are closely arranged on their respective pads in the traditional horizontal wiring manner.

[0062] Figure 2 is Figure 1 The two-stage electrical model of the shown structure. Assume that capacitors C1 and C2 are exactly the same. Among them, Vs is the excitation source; Rs is the source impedance; C is the capacitance of capacitors C1 and C2; Rc is the equivalent series resistance of capacitors C1 and C2. Since Rc only affects the amplitude at the resonant point, the value of Rc is temporarily ignored here; Lc is the equivalent series inductance of capacitors C1 and C2; Mc is the mutual inductance between the two capacitors; Ld is the equivalent inductance formed by the loop between the two capacitors. Since Ld is basically perpendicular to the capacitors, the mutual inductance between Ld and the capacitors is very small, so their mutual inductance is ignored; RL is the load resistance; Vo is the voltage drop across the load resistance. Assume that the load impedance matches the source impedance, and RL = Rs = R, then the insertion gain S of the voltage Vo with respect to the source Vs 21_Tradition can be expressed as:

[0063]

[0064] In the formula:

[0065]

[0066] K 2 = ωRC + j[ω 2 C(L C + M C ) - 1]

[0067]

[0068] Define the coupling coefficient k between the two capacitors as k = Mc / Lc. According to Equation (1), the curve of the insertion gain S of the traditional two-capacitor parallel filter with respect to the coupling coefficient k can be plotted, as 21_Tradition shown with the change of the coupling coefficient k, as Figure 3As shown. It can be seen from the figure that as the coupling degree between the two capacitors increases, the high-frequency filtering performance of the filter gradually decreases. The noise of the first capacitor loop is directly coupled to the second capacitor loop and transmitted to the load resistor of the filter, which is one of the reasons why it is difficult to suppress the high-frequency ripple of the output of the high-frequency resonant converter. In this case, the coupling relationship between the two capacitors is an adverse coupling.

[0069] In order to reduce the adverse coupling between capacitors in the traditional multi-capacitor parallel filter, improve the high-frequency performance of the filter, and improve the suppression effect of the high-frequency ripple of the DC output of the high-frequency DC-DC resonant converter, the present invention adopts Figure 4 the high-frequency ripple suppression circuit shown. The special feature of this filter is that the current directions flowing through every two adjacent capacitors are opposite, and the length of the PCB trace connecting the two capacitors is larger than that of the traditional parallel connection method and forms a 45° angle with the adjacent capacitor. Therefore, this high-frequency ripple suppression circuit can be equivalent to a multi-stage π-type filter, and its equivalent circuit is as shown in Figure 5 Figure. Where Lc1~Lcn and Rc1~Rcn are the equivalent series inductance and equivalent series resistance of capacitors C1~Cn respectively, Ld1~Ldn are the equivalent inductances formed by the loops between every two adjacent capacitors, Mc1-Ld1 is the mutual inductance between capacitor C1 and Ld1, Mc1-c2 is the mutual inductance between capacitor C1 and C2, and so on, Mcn-Ldn-1 is the mutual inductance between capacitor Cn and Ldn-1, and Mcn-1-cn is the mutual inductance between capacitor Cn-1 and Cn.

[0070] Figure 6 is Figure 5 the two-stage model of the equivalent circuit shown. The definition of its circuit parameters is the same as that of the two-stage model of the traditional filter described above. Supplementary assumption: Ld1 = Ld, Mc1-Ld1 = Mc2-Ld1 = Mcd, Mc1-c2 = Mc, then the insertion gain S of voltage Vo to source Vs 21_New can be expressed as:

[0071]

[0072] In the formula:

[0073]

[0074] A 2 = ω 2 C(L C -M cd ) - 1 - jωRC

[0075]

[0076] Define the coupling coefficient k between the two capacitors c = M c / Lc , the coupling coefficient between the capacitor and Ld According to Equation (1) and Equation (2), the insertion gain S of the two-stage model of the traditional multi-capacitor parallel filter is plotted 21_Tradition and the insertion gain S of the two-stage model of the high-frequency ripple suppression circuit of the present invention 21_New The comparison curves under the same kc are shown. It can be seen from the figure that the two-capacitor parallel connection method of the present invention can convert the adverse coupling of the traditional parallel connection method into favorable coupling, change the characteristics of the high-frequency band of the filter, and thus is beneficial to filtering the high-frequency ripple output by the previous stage. Overall, the two-capacitor parallel connection method of the present invention uses the parasitic parameters of the PCB line and the capacitor to equivalent the two-capacitor filter to a π-type filter, and this π-type filter effectively improves the high-frequency performance of the filter.

[0077] It can be seen that the high-frequency ripple suppression circuit composed of the two-capacitor parallel filter in this example as the basic module can further improve the high-frequency characteristics of the filter, better meet the requirements for suppressing the high-frequency ripple of the DC output of the high-frequency DC-DC resonant converter, and thus improve the performance index of the power converter.

[0078] Embodiment 2:

[0079] As Figure 8 shown, this embodiment is composed of an inverter (10), a matching network (20), a rectifier (30), a high-frequency ripple suppression circuit (2), a load (50), a hysteresis control circuit (60) and a drive circuit (70). The DC input voltage VIN of the high-frequency DC-DC resonant converter generates a high-frequency AC voltage after passing through the inverter and outputs it to the matching network. Then, the rectifier converts the AC voltage output by the previous stage into a DC voltage. After passing through the high-frequency ripple suppression circuit, a large amount of high-frequency ripple output by the previous stage is filtered out. Under the action of the hysteresis control circuit (60) and the drive circuit (70), the load (50) finally obtains a DC output voltage VO with a smaller high-frequency ripple component.

[0080] Referring to Figure 8 , taking the high-frequency isolated DC-DC resonant converter as an example, in the circuit: the inverter adopts a Class Φ2 inverter circuit composed of LF, CF, Q, L2F and C2F, which inversely converts the input DC voltage into an AC voltage. The incorporated L2F and C2F branches make the drain-source voltage of the switching transistor Q form a saddle wave, thereby reducing the voltage stress.

[0081] The matching network is composed of CS, LS and a transformer T. Among them, CS plays a role in blocking DC, and it jointly adjusts the output power of the inverter (1) with the inductor LS and the transformer T.

[0082] The rectifier uses a voltage - type Class - E rectifier composed of Lr, Cr, D, and Co, which converts the AC power output by the previous stage into DC power. The diode D can achieve zero - current turn - off and its junction capacitance can be absorbed by the resonant capacitor Cr. The leakage inductance of the transformer T and the parasitic inductance of the PCB can be absorbed by the resonant inductor Lr.

[0083] The hysteresis control circuit uses a hysteresis controller composed of R1, R2, R3, R4, and comp. The output voltage VOUT is compared with the reference voltage Vref through the comparator comp, so that the main circuit operates in the hysteresis mode, thereby stabilizing the output voltage VO.

[0084] The drive circuit consists of an oscillation chip, an RC delay circuit, a buffer, an AND - gate logic, and a drive chip. The oscillation chip emits a square - wave signal with a duty cycle of 0.5. After passing through the RC delay circuit and the buffer, a square - wave signal with a duty cycle of 0.3 is obtained to control the drive chip to drive the switching transistor Q to work.

[0085] The high - frequency ripple suppression circuit refers to Figure 4 , which consists of capacitors C1, C2... Cn, PCB traces, and pads connecting the n capacitors and the PCB traces. One end of the capacitor C1 is connected to the positive electrode of Vo1, and the other end of C1 is connected to the negative electrode of Vo1; one end of the capacitor C2 is connected to one end of the capacitor C1 connected to the positive electrode of Vo1 through a PCB trace, and the other end of C2 is connected to the negative electrode of Vo1; and so on. One end of the capacitor Cn is connected to one end of the capacitor Cn - 1 connected to the positive electrode of Vo1 through a PCB trace, and the other end of Cn is connected to the negative electrode of Vo1; the current directions flowing through every two adjacent capacitors among the n capacitors are opposite; the positive electrode of the load end is connected to one end of the capacitor Cn connected to the positive electrode of Vo1, and the negative electrode of the load end is connected to the negative electrode of Vo1. The ends of the n capacitors connected to the negative electrode of Vo1 are connected by vias. The PCB traces connecting every three adjacent capacitors adopt V - shaped and inverted - V - shaped traces. The specific number of capacitors can be determined according to the actual situation, and the capacitance specifications generally use chip capacitors with better high - frequency characteristics.

[0086] For the embodiment, when the high - frequency ripple suppression circuit of the present invention is adopted, the high - frequency ripple of the output voltage is 285 mV, and when the traditional simple capacitor - parallel high - frequency ripple suppression circuit is adopted, the high - frequency ripple of the output voltage is 450 mV, which is reduced by about 37% compared with that of the traditional one. The present invention effectively reduces the high - frequency ripple, and the effect is remarkable.

[0087] The above - mentioned are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. Method for suppressing high-frequency ripple of DC output of DC-DC converter, Characterized in that: The method is based on a high-frequency ripple suppression circuit for the DC output of a high-frequency DC-DC resonant converter. This circuit includes the DC output terminal Vo1 of the high-frequency DC-DC resonant converter, a high-frequency ripple suppression circuit, and a load terminal Vo; the filter capacitors of the high-frequency ripple suppression circuit include a first capacitor, a second capacitor... an nth capacitor; One end of the first capacitor is connected to the positive pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter, and the other end of the first capacitor is connected to the negative pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter; one end of the second capacitor is connected to one end of the first capacitor connected to the positive pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter through a PCB trace, and the other end of the second capacitor is connected to the negative pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter; and so on, one end of the nth capacitor is connected to one end of the (n - 1)th capacitor connected to the positive pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter through a PCB trace, and the other end of the nth capacitor is connected to the negative pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter; the current directions flowing through every two adjacent capacitors among the n capacitors are opposite; the positive pole of the load terminal Vo is connected to one end of the nth capacitor connected to the positive pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter, and the negative pole of the load terminal Vo is connected to the negative pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter; One end of the n capacitors connected to the negative pole of the DC output terminal Vo1 of the high-frequency DC-DC resonant converter is connected by a via; In the high-frequency ripple suppression circuit, the first capacitor, the second capacitor... the nth capacitor are all filter capacitors. The n filter capacitors are cross-connected in parallel by V-shaped and inverted V-shaped PCB trace patterns. The current directions flowing through every two adjacent capacitors are opposite. The PCB trace connecting the two capacitors is lengthened and forms a 45° angle with the adjacent capacitor, so that the parasitic parameters of the n capacitors and the PCB traces form a filter with excellent high-frequency characteristics, that is, the high-frequency ripple suppression circuit is equivalent to a multi-stage π-type filter, improving the high-frequency ripple suppression ability of the DC output; In the high-frequency ripple suppression circuit, the number of capacitors n is an integer greater than or equal to 2.

2. The method for suppressing high-frequency ripple of DC output of a DC-DC converter according to claim 1, Characterized in that: In the high-frequency ripple suppression circuit, the PCB traces connecting every three adjacent capacitors adopt V-shaped and inverted V-shaped traces.

3. The method for suppressing high-frequency ripple of DC output of a DC-DC converter according to claim 1, Characterized in that: The high-frequency ripple suppression circuit can be decoupled from the main circuit of the high-frequency DC-DC resonant converter.

4. The method for suppressing high-frequency ripple of DC output of a DC-DC converter according to claim 1, Characterized in that: The packaging form of the n capacitors of the high-frequency ripple suppression circuit is surface mount packaging.

5. The DC output high-frequency ripple suppression method for the DC-DC converter according to claim 1, characterized in that: the high-frequency ripple suppression circuit further includes a PCB trace and pads for connecting n capacitors and the PCB trace.

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