DC / DC converter

Abstract

The DC / DC converter comprises a first coupling inductor first winding, a first coupling inductor second winding, a second coupling inductor first winding, a second coupling inductor second winding, an energy storage capacitor, a first switch, a second switch, a third switch and a fourth switch which are connected in an interleaved Boost topological form. According to the DC / DC converter provided by the invention, the gain can be adjusted by adjusting the duty ratio and / or the turn ratio of the coupling inductor, and the duty ratio can be prevented from reaching the limit condition while the high voltage gain of the circuit is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, and in particular to a DC / DC (direct current to direct current) converter. Background Art

[0002] With the continuous development of clean energy, new energy resources such as photovoltaics are widely used and studied. However, due to the low output voltage of photovoltaic and other new energy power generation systems, they cannot directly supply power to the grid. Therefore, high voltage gain DC / DC converters are particularly important.

[0003] Figure 1 A conventional DC / DC converter (Boost converter) is shown. The Boost converter has a simple structure and can achieve a higher voltage gain by increasing the duty cycle D. However, when the duty cycle becomes larger, it is easy to cause reliability problems. At the same time, when the input side current is large, in order to control the input current ripple, a larger inductor and capacitor need to be placed on the input side of the Boost converter, which increases the circuit cost and size.

[0004] Considering the influence of input current ripple, the interleaved parallel Boost converter is currently widely used, such as Figure 2 However Figure 2 The voltage gain of the conventional interleaved parallel Boost converter shown is also related to the duty cycle. Since the extreme duty cycle situation must be avoided, it is also difficult to achieve a high voltage gain. Summary of the invention

[0005] The present application provides a DC / DC converter including coupled inductors and having an interleaved parallel Boost topology. The DC / DC converter can adjust the gain by adjusting the duty cycle and / or the turns ratio of the coupled inductors, and can achieve a high voltage gain of the circuit by adjusting the turns ratio of the coupled inductors while avoiding the duty cycle reaching an extreme condition.

[0006] According to an embodiment of the present invention, a DC / DC converter is provided, comprising: a first coupled inductor first winding, having a first end and a second end, wherein the first end of the first coupled inductor first winding is coupled to an input end; a first coupled inductor second winding, having a first end and a second end; a second coupled inductor first winding, having a first end and a second end, wherein the first end of the second coupled inductor first winding is coupled to the input end; a second coupled inductor second winding, having a first end and a second end; an energy storage capacitor, having a first end and a second end, wherein the energy storage capacitor, the first coupled inductor second winding and the second coupled inductor second winding are coupled in series between the second end of the first coupled inductor first winding and a switch end; a first switch, having a first end and a second end, the first end of the first switch is coupled to the second end of the first winding of the first coupled inductor, and the second end of the first switch is grounded; a second switch having a first end and a second end, the first end of the second switch is coupled to the second end of the first winding of the second coupled inductor, and the second end of the second switch is grounded; a first freewheeling switch having a first end and a second end, the first end of the first freewheeling switch is coupled to the switch end, and the second end of the first freewheeling switch is coupled to the output end; and a second freewheeling switch having a first end and a second end, the first end of the second freewheeling switch is coupled to the second end of the first winding of the second coupled inductor, and the second end of the second freewheeling switch is coupled to the switch end.

[0007] According to an embodiment of the present invention, a DC / DC converter is provided, comprising: a plurality of coupled inductors including a first coupled inductor, wherein each coupled inductor includes a first winding and a second winding, each winding includes a first end and a second end, wherein the first end of the first winding of each coupled inductor is coupled to an input end; an energy storage capacitor having a first end and a second end, the energy storage capacitor being coupled in series with the second winding of each coupled inductor between the second end of the first winding of the first coupled inductor and a switch end; a plurality of switches, each switch being coupled between the second end of the first winding of the corresponding coupled inductor and ground; and a plurality of freewheeling switches including a first freewheeling switch, the first freewheeling switch being coupled between the switch end and the output end, and the remaining freewheeling switches being coupled between the second end of the first winding of the corresponding coupled inductor and the switch end. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The above and other objects, features and advantages of the present application will become more apparent through the following description of the embodiments of the present application with reference to the accompanying drawings:

[0009] Figure 1 A conventional DC / DC converter 100 is shown;

[0010] Figure 2 It is a schematic diagram of the circuit structure of a traditional interleaved parallel Boost converter;

[0011] Figure 3 is a schematic diagram of a circuit structure of a DC / DC converter 300 according to an embodiment of the present invention;

[0012] Figure 4 Schematic diagrams of waveforms of control signals G1 and G2, input current Iin, current iL11 flowing through the first winding L11 of the first coupled inductor, current iL21 flowing through the first winding L21 of the second coupled inductor, current iS1 flowing through the first switch S1, current iS2 flowing through the second switch S2, current iD1 flowing through the third switch D1, and current iD2 flowing through the fourth switch D2 of the DC / DC converter 300 according to an embodiment of the present invention are shown;

[0013] Figure 5 The present invention shows an embodiment of Figure 4 The state of the DC / DC converter 300 during the period t1-t2 is shown;

[0014] Figure 6 The present invention shows an embodiment of Figure 4 The state of the DC / DC converter 300 during the period t2-t3 and the period t4-t5 is shown;

[0015] Figure 7 The present invention shows an embodiment of Figure 4 The state of the DC / DC converter 300 during the period t3-t4 is shown;

[0016] Figure 8 shows a gain curve diagram of a DC / DC converter 300 according to an embodiment of the present application;

[0017] Fig. 9 FIG. 1 is a schematic diagram of a circuit structure of a DC / DC converter 900 according to an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details do not have to be used to implement the present invention. In other examples, in order to avoid confusing the present invention, known circuits, materials or methods are not specifically described.

[0019] The terms "first", "second", etc. in the following description are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0020] In addition, in the present application, directional terms such as "upper" and "lower" may be defined including but not limited to the orientation relative to the schematic placement of the components in the drawings. It should be understood that these directional terms may be relative concepts, which are used for relative description and clarification, and may change accordingly according to the change in the orientation of the components in the drawings.

[0021] In this application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. In addition, the term "coupling" can be a way of achieving electrical connection for signal transmission. "Coupling" can be a direct electrical connection or an indirect electrical connection through an intermediate medium.

[0022] Figure 3 The circuit structure diagram of a DC / DC converter 300 according to an embodiment of the present invention. The DC / DC converter 300 has an input terminal IN for receiving an input voltage Vin, and an output terminal OUT for providing an output voltage Vout to a load. Figure 3 In the embodiment, the input voltage Vin is provided by a voltage source, and the load of the DC / DC converter 300 is represented by a resistor RL. It should be understood that in practical applications, the input voltage Vin can be provided by a front-stage circuit, and the load can be a rear-stage circuit, an LED, a computer chip, etc.

[0023] The DC / DC converter 300 includes a first coupled inductor first winding L11, a first coupled inductor second winding L12, a second coupled inductor first winding L21, a second coupled inductor second winding L22, an energy storage capacitor C1, a first switch S1, a second switch S2, a first freewheeling switch D1 and a second freewheeling switch D2.

[0024] like Figure 3The first coupled inductor first winding L11 and the first coupled inductor second winding L12 are coupled to each other. The first coupled inductor first winding L11 has a first end and a second end, and its first end is coupled to the input end IN to receive the input voltage Vin, and the second end is coupled to the first end of the energy storage capacitor C1. The second coupled inductor first winding L21 and the second coupled inductor second winding L22 are coupled to each other. The second coupled inductor first winding L21 has a first end and a second end, and its first end is coupled to the input end IN to receive the input voltage Vin. The first coupled inductor second winding L12 and the second coupled inductor second winding L22 have a first end and a second end respectively, and the energy storage capacitor C1, the first coupled inductor second winding L12 and the second coupled inductor second winding L22 are coupled in series between the second end of the first coupled inductor first winding L11 and the switch end K1.

[0025] exist Figure 3 In the embodiment, the first end of the first coupled inductor first winding L11 and the first end of the first coupled inductor second winding L12 are the same-named ends, the first end of the second coupled inductor first winding L21 and the second end of the second coupled inductor second winding L22 are the same-named ends, the first end of the first coupled inductor second winding L12 is coupled to the second end of the energy storage capacitor C1, the first end of the second coupled inductor second winding L22 is coupled to the second end of the first coupled inductor second winding L12, and the second end is coupled to the switch terminal K1. It should be understood that in other embodiments, the energy storage capacitor C1, the first coupled inductor second winding L12, and the second coupled inductor second winding L22 coupled in series can swap their positions in the connection branch.

[0026] In one embodiment, the turns ratio of the second winding L12 of the first coupled inductor to the first winding L11 of the first coupled inductor is n:1, and the turns ratio of the second winding L22 of the second coupled inductor to the first winding L21 of the second coupled inductor is also n:1, where n≥1. In some embodiments, considering the coupling effect and the loss of the coupled inductor, 1≤n≤3.

[0027] The first switch S1 has a first end coupled to the second end of the first winding L11 of the first coupled inductor, and a second end coupled to the ground GND. The second switch S2 has a first end coupled to the second end of the first winding L21 of the second coupled inductor, and a second end coupled to the ground GND. The first freewheeling switch D1 has a first end coupled to the switch terminal K1, and a second end coupled to the output terminal OUT. The second freewheeling switch D2 has a first end coupled to the second end of the first winding L21 of the second coupled inductor, and a second end coupled to the switch terminal K1.

[0028] exist Figure 3 In the embodiment, the DC / DC converter 300 further includes an output capacitor Co coupled between the output terminal and the ground GND for filtering.

[0029] exist Figure 3 In an embodiment, the first switch S1 and the second switch S2 include MOSFET (Metal Oxide Semiconductor Field Effect Transistor). In other embodiments, the first switch S1 and the second switch S2 also include other controllable switches such as JFET (Junction Field Effect Transistor), IGBT (Insulated Gate Bipolar Transistor), BJT (Bipolar Junction Transistor), etc. The first switch S1 has a control end for receiving a first control signal G1, and the second switch S2 has a control end for receiving a second control signal G2. The first switch S1 and the second switch S2 are turned on and off under the control of the first control signal G1 and the second control signal G2, respectively.

[0030] exist Figure 3 In an embodiment, the first freewheeling switch D1 and the second freewheeling switch D2 include diodes. The anode of the first freewheeling switch D1 is coupled to the switch terminal K1, and the cathode is coupled to the output terminal OUT. The anode of the second freewheeling switch D2 is coupled to the second end of the first winding L21 of the second coupled inductor, and the cathode is coupled to the switch terminal K1. In other embodiments, the first freewheeling switch D1 and the second freewheeling switch D2 may also be controllable switches such as the first switch S1 and the second switch S2. The control circuit provides a control signal to control the switching timing of the first switch S1, the second switch S2, the first freewheeling switch D1 and the second freewheeling switch D2.

[0031] Figure 4 A schematic diagram of waveforms of control signals G1 and G2, input current Iin, current iL11 flowing through the first winding L11 of the first coupled inductor, current iL21 flowing through the first winding L21 of the second coupled inductor, current iS1 flowing through the first switch S1, current iS2 flowing through the second switch S2, current iD1 flowing through the first freewheeling switch D1, and current iD2 flowing through the second freewheeling switch D2 of a DC / DC converter 300 according to an embodiment of the present invention is shown. Figure 5 The present invention shows an embodiment of Figure 4 The state of the DC / DC converter 300 during the period t1 - t2 is shown. Figure 6 The present invention shows an embodiment of Figure 4 The states of the DC / DC converter 300 in the periods t2 - t3 and t4 - t5 are shown. Figure 7 The present invention shows an embodiment of Figure 4 The state of the DC / DC converter 300 during the period t3-t4 is shown. Figure 4-Figure 7 To illustrate the working principle of the DC / DC converter 300 of the present application.

[0032] like Figure 4 and Figure 5 As shown, during the period t1-t2, the first switch S1 is turned on, the second switch S2 is turned off, the second freewheeling switch D2 is freewheeling, and the first freewheeling switch D1 is turned off. Figure 5 The circuits and devices that are not involved are faded for illustration. At this time, the current flows from the voltage source through the first winding L11 of the first coupled inductor and the first switch S1 to the ground GND, and the voltage VL1 across the first winding L11 of the first coupled inductor is equal to the input voltage Vin, and the first winding L11 of the first coupled inductor stores energy. In addition, the current flows from the voltage source through the first winding L21 of the second coupled inductor, the second freewheeling switch D2, the second winding L22 of the second coupled inductor, the second winding L12 of the first coupled inductor, the energy storage capacitor C1 and the first switch S1 to the ground GND, and the first winding L21 of the second coupled inductor releases energy. In this working state, the circuit loop equation is:

[0033]

[0034] VL1 is the voltage across the first winding L11 of the first coupled inductor, and NVL1 is the voltage across the second winding L12 of the first coupled inductor. VL2 is the voltage across the first winding L21 of the second coupled inductor, and NVL2 is the voltage across the second winding L22 of the second coupled inductor. N is the turns ratio between the second winding L12 of the first coupled inductor and the first winding L11 of the first coupled inductor, and is also the turns ratio between the second winding L22 of the second coupled inductor and the first winding L21 of the second coupled inductor. VC1 is the voltage across the energy storage capacitor C1.

[0035] like Figure 4 and Figure 6 As shown, during the period t2-t3, the first switch S1 and the second switch S2 are turned on, and the first freewheeling switch D1 and the second freewheeling switch D2 are turned off. Figure 6 The circuits and devices that are not involved are faded for illustration. At this time, the current flows from the voltage source through the first winding L11 of the first coupled inductor and the first switch S1 to the ground GND, the voltage VL1 across the first winding L11 of the first coupled inductor is equal to the input voltage Vin, and the first winding L11 of the first coupled inductor stores energy. In addition, the current flows from the voltage source through the first winding L21 of the second coupled inductor and the second switch S2 to the ground GND, the voltage VL2 across the first winding L21 of the second coupled inductor is equal to the input voltage Vin, and the first winding L21 of the second coupled inductor stores energy. In this working state, the circuit loop equation is:

[0036]

[0037] like Figure 4 and Figure 7 As shown, during the period t3-t4, the first switch S1 is turned off, the second switch S2 is turned on, the second freewheeling switch D2 is turned off, and the first freewheeling switch D1 is freewheeling. Figure 7 The circuits and devices that are not involved are faded for illustration. At this time, the current flows from the voltage source through the first winding L21 of the second coupled inductor and the second switch S2 to the ground GND, and the voltage VL2 across the first winding L21 of the second coupled inductor is equal to the input voltage Vin, and the first winding L21 of the second coupled inductor stores energy. In addition, the current flows from the voltage source through the first winding L11 of the first coupled inductor, the energy storage capacitor C1, the second winding L12 of the first coupled inductor, the second winding L22 of the second coupled inductor, the first freewheeling switch D1 and the load RL to the ground GND, and the first winding L11 of the first coupled inductor releases energy. In this working state, the circuit loop equation is:

[0038]

[0039] During the period t4-t5, the circuit switch state is the same as that during the period t2-t3, that is, Figure 6 As shown, the first winding L11 of the first coupled inductor and the first winding L21 of the second coupled inductor store energy.

[0040] At time t5, a switching cycle of the DC / DC converter 300 ends, a new switching cycle begins, and the working state repeats the state starting from time t1.

[0041] According to the volt-second balance law of inductance, based on the above formulas (1) to (3), we can get:

[0042]

[0043] Wherein, D is the duty cycle of the first switch S1 and the second switch S2 in a switching cycle, that is, the ratio of the switch on time to the switching cycle time. In the embodiment of the present application, the duty cycle of the first switch S1 and the second switch S2 is the same, and D≥0.5.

[0044] Figure 8 FIG. 4 shows a gain curve diagram of a DC / DC converter 300 according to an embodiment of the present application. Figure 8 The relationship between the gain G, duty cycle D and turns ratio n shown is based on the above formula (4). Figure 8 It can be seen that when the turns ratio n is fixed, the voltage gain G increases with the increase of the duty cycle. The voltage gain G of different turns ratios n is also different, such as Figure 8As shown, the larger the turns ratio n is, the larger the voltage gain G is. The DC / DC converter 300 can obtain a suitable boost ratio by selecting the duty cycle D and the turns ratio n at the same time, so that the high gain of the circuit can be achieved by adjusting the turns ratio n while avoiding the duty cycle D from reaching the limit condition.

[0045] Fig. 9 Schematic diagram of the circuit structure of a DC / DC converter 900 according to an embodiment of the present invention. The DC / DC converter 900 is derived from the multi-phase expansion of the DC / DC converter 300. The DC / DC converter 900 includes a plurality of coupled inductors L1-Lm, a storage capacitor C1, a plurality of switches S1-Sm and a plurality of freewheeling switches D1-Dm, where m is an integer greater than or equal to 2.

[0046] like Fig. 9 Each coupled inductor includes a first winding and a second winding, for example, the first coupled inductor L1 includes a first winding L11 and a second winding L12, and the mth coupled inductor Lm includes a first winding Lm1 and a second winding Lm2. Each coupled inductor first winding has a first end and a second end, and its first end is coupled to the input terminal IN to receive the input voltage Vin. The second end of the first winding L11 of the first coupled inductor is coupled to the first end of the energy storage capacitor C1, and the second ends of the first windings of the remaining coupled inductors are coupled to the connection point of the corresponding switch and the freewheeling switch. The energy storage capacitor C1 and the second windings L12-Lm2 of the multiple coupled inductors are coupled in series between the second end of the first winding L11 of the first coupled inductor and the switch terminal K1. The first end of each second winding of the multiple coupled inductors second windings L12-Lm2 is connected to the second end of another second winding.

[0047] exist Fig. 9 In the embodiment, the first end of the first winding of the first coupled inductor and the first end of the second winding are the same-named ends, and the first end of the first winding of each of the remaining coupled inductors and the second end of the second winding are the same-named ends. It should be understood that in other embodiments, the energy storage capacitor C1 and the second windings L12-Lm2 of the plurality of coupled inductors coupled in series can be swapped in position in the connection branch.

[0048] In one embodiment, the turns ratio of the second winding to the first winding of each coupled inductor is n:1, where n≥1. In some embodiments, considering the coupling effect and the loss of the coupled inductor, 1≤n≤3.

[0049] Each of the plurality of switches S1-Sm has a first end coupled to the second end of the first winding of the corresponding coupled inductor, and the second end of the switch is grounded GND. The first freewheeling switch D1 is coupled between the switch terminal K1 and the output terminal OUT, and each of the remaining freewheeling switches D2-Dm has a first end coupled to the second end of the first winding of the corresponding coupled inductor, and the second ends of the freewheeling switches D2-Dm are all coupled to the switch terminal K1.

[0050] In the DC / DC converter 900, the duty cycles D of the multiple switches S1-Sm are consistent. In one embodiment, to increase the gain and ensure stable operation of the circuit, D≥(m-1) / m.

[0051] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0052] The above is only a preferred embodiment of the present application and does not constitute any formal limitation to the present application. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present application using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present application, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still fall within the scope of protection of the technical solution of the present application.

Claims

1. A DC / DC converter, comprising: A first coupled inductor first winding has a first end and a second end, wherein the first end of the first coupled inductor first winding is coupled to the input end; The first coupled inductor second winding has a first end and a second end; A first winding of a second coupled inductor has a first end and a second end, wherein the first end of the first winding of the second coupled inductor is coupled to the input end; A second coupled inductor second winding having a first end and a second end; An energy storage capacitor having a first end and a second end, wherein the energy storage capacitor, the second winding of the first coupled inductor and the second winding of the second coupled inductor are coupled in series between the second end of the first winding of the first coupled inductor and a switch end; A first switch having a first end and a second end, wherein the first end of the first switch is coupled to the second end of the first winding of the first coupled inductor, and the second end of the first switch is grounded; A second switch having a first end and a second end, wherein the first end of the second switch is coupled to the second end of the first winding of the second coupled inductor, and the second end of the second switch is grounded; A first freewheeling switch having a first end and a second end, wherein the first end of the first freewheeling switch is coupled to the switch end, and the second end of the first freewheeling switch is coupled to the output end; as well as The second freewheeling switch has a first end and a second end, wherein the first end of the second freewheeling switch is coupled to the second end of the first winding of the second coupled inductor, and the second end of the second freewheeling switch is coupled to the switch end.

2. The DC / DC converter as claimed in claim 1, wherein the duty cycles of the first switch and the second switch are the same. 3 . The DC / DC converter as claimed in claim 2 , wherein a duty ratio of the first switch and the second switch is greater than or equal to 0.

5.

4. The DC / DC converter of claim 1, wherein the first switch and the second switch comprise MOSFET devices.

5. The DC / DC converter of claim 1, wherein the first freewheeling switch and the second freewheeling switch comprise diodes.

6. The DC / DC converter of claim 1, wherein a turns ratio between the second winding of the second coupled inductor and the first winding of the second coupled inductor is the same as a turns ratio between the second winding of the first coupled inductor and the first winding of the first coupled inductor, and the turns ratio is greater than or equal to 1. 7 . The DC / DC converter as claimed in claim 6 , wherein the turns ratio is less than or equal to 3. 8 . The DC / DC converter as claimed in claim 1 , further comprising an output capacitor coupled between the output terminal and ground.

9. A DC / DC converter, comprising: A plurality of coupled inductors including a first coupled inductor, wherein each coupled inductor includes a first winding and a second winding, each winding includes a first end and a second end, wherein the first end of the first winding of each coupled inductor is coupled to the input end; An energy storage capacitor having a first end and a second end, wherein the energy storage capacitor is coupled in series with the second winding of each coupled inductor and between the second end of the first winding of the first coupled inductor and the switch end; A plurality of switches, each switch being coupled between the second end of the first winding corresponding to the coupled inductor and ground; as well as A plurality of freewheeling switches including a first freewheeling switch is coupled between a switch terminal and an output terminal, and each of the remaining freewheeling switches is coupled between a second terminal of a first winding of a corresponding coupled inductor and the switch terminal.

10. The DC / DC converter of claim 9, wherein the duty cycles of the plurality of switches are the same. 11 . The DC / DC converter of claim 10 , wherein a duty cycle of the plurality of switches is greater than or equal to (m-1) / m, where m is the number of switches.

12. The DC / DC converter of claim 9, wherein the plurality of switches comprise MOSFET devices.

13. The DC / DC converter of claim 9, wherein the plurality of freewheeling switches comprise diodes. 14 . The DC / DC converter of claim 9 , wherein the turns ratio of the second winding of each coupled inductor is the same as that of the first winding, and the turns ratio is greater than or equal to 1. 15 . The DC / DC converter of claim 14 , wherein the turns ratio is less than or equal to 3.

Images