Flying capacitor three-level DC / DC converter

Abstract

The utility model provides a flying capacitor three-level DC / DC converter. Under normal conditions, a flying capacitor three-level power conversion bridge is arranged between two poles of a high-voltage side of the flying capacitor three-level DC / DC conversion circuit; one end of a flying capacitor in the flying capacitor three-level power conversion bridge is connected with a high-voltage side positive electrode of the flying capacitor three-level DC / DC conversion circuit through a diode of an upper tube in an upper half bridge of the flying capacitor three-level power conversion bridge; the other end of the flying capacitor is connected with a high-voltage side negative electrode of the flying capacitor three-level DC / DC conversion circuit through a diode of a lower tube of a lower half bridge of the flying capacitor three-level power conversion bridge, so that the two ends of the flying capacitor can be communicated with the two ends of the discharging circuit; and the discharge circuit is in an on state when the flying capacitor three-level DC / DC converter stops working, so that the flying capacitor can discharge when the flying capacitor three-level DC / DC converter stops working.

Description

Technical Field

[0001] The utility model relates to the technical field of power conversion, in particular to a flying capacitor three-level DC / DC converter. Background Art

[0002] By developing photovoltaic energy storage and electrolysis hydrogen production technology, we can reduce dependence on traditional energy and improve the security of energy supply. Among them, the flying capacitor three-level DC / DC converter is the main equipment of the off-grid hydrogen production system.

[0003] However, currently, when the flying capacitor three-level DC / DC converter stops working, there is still electricity on the flying capacitor, which poses a safety hazard.

[0004] Therefore, how to discharge the flying capacitor when the flying capacitor three-level DC / DC converter stops working is a technical problem that needs to be solved urgently. Utility Model Content

[0005] In view of this, the utility model provides a flying capacitor three-level DC / DC converter, so that the flying capacitor is discharged when the flying capacitor three-level DC / DC converter stops working.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] The present application provides a flying capacitor three-level DC / DC converter, comprising: a flying capacitor three-level DC / DC conversion circuit and a discharge circuit; wherein:

[0008] The two ends of the discharge circuit are respectively connected to: the two poles of the high voltage side of the flying capacitor three-level DC / DC conversion circuit;

[0009] The discharge circuit is in a conduction state when the flying capacitor three-level DC / DC converter stops working.

[0010] Optionally, it further includes: a first pre-charging circuit; wherein:

[0011] The output end of the first pre-charging circuit is connected to: the positive electrode of the high voltage side of the flying capacitor three-level DC / DC conversion circuit;

[0012] An input end of the first pre-charging circuit receives a first supply voltage;

[0013] The first pre-charging circuit is in a conducting state when the flying capacitor three-level DC / DC converter does not start working, and the upper tube of the upper half bridge of each flying capacitor three-level power conversion bridge in the flying capacitor three-level DC / DC conversion circuit is turned on when the flying capacitor three-level DC / DC converter does not start working.

[0014] Optionally, it further includes: a second pre-charging circuit; wherein:

[0015] The output end of the second pre-charging circuit is connected to: the positive electrode on the high voltage side of the flying capacitor three-level DC / DC conversion circuit;

[0016] An input end of the second pre-charging circuit receives a second supply voltage;

[0017] The second pre-charging circuit is in a conducting state when the flying capacitor three-level DC / DC converter does not start to operate.

[0018] Optionally, the second pre-charging circuit comprises: a first switch and a first resistor; wherein:

[0019] The first switch and the first resistor are connected in series, and the series branches formed are respectively used as the input end and the output end of the second pre-charging circuit;

[0020] The control end of the first switch serves as the control end of the second pre-charging circuit.

[0021] Optionally, the first pre-charging circuit includes: a second switch and a second resistor; wherein:

[0022] The second switch and the second resistor are connected in series, and the series branches formed are respectively used as the input end and the output end of the first pre-charging circuit;

[0023] The control end of the second switch serves as the control end of the first pre-charging circuit.

[0024] Optionally, it further includes: at least two absorption circuits; wherein:

[0025] One of the absorption circuits is connected in parallel between the two ends of the upper half bridge of each flying capacitor three-level power conversion bridge in the flying capacitor three-level DC / DC conversion circuit;

[0026] An absorption circuit is connected in parallel between the two ends of the lower half bridge of each flying capacitor three-level power conversion bridge.

[0027] Optionally, the discharge circuit includes: a third switch and a third resistor; wherein:

[0028] The third switch and the third resistor are connected in series, and the series branches formed are respectively used as two ends of the discharge circuit;

[0029] The control end of the third switch serves as the control end of the discharge circuit.

[0030] Optionally, the flying capacitor three-level DC / DC conversion circuit comprises: at least one flying capacitor three-level power conversion bridge, at least one inductor and two capacitors; wherein:

[0031] The positive electrode and the negative electrode of each flying capacitor three-level power conversion bridge respectively correspond to the positive electrode and the negative electrode of the high voltage side of the flying capacitor three-level DC / DC conversion circuit;

[0032] A first capacitor is provided between two electrodes on the high voltage side of the flying capacitor three-level DC / DC conversion circuit;

[0033] The midpoint of each flying capacitor three-level power conversion bridge is connected to: one end of the inductor corresponding to itself;

[0034] The other end of each of the inductors serves as the positive electrode of the low voltage side of the flying capacitor three-level DC / DC conversion circuit;

[0035] The negative electrode of each flying capacitor three-level power conversion bridge serves as the negative electrode of the low voltage side of the flying capacitor three-level DC / DC conversion circuit;

[0036] A second capacitor is arranged between two electrodes on the low voltage side of the flying capacitor three-level DC / DC conversion circuit.

[0037] Optionally, the flying capacitor three-level power conversion bridge comprises: a flying capacitor and four switch tubes; wherein:

[0038] The input end of the first switch tube serves as the positive electrode of the flying capacitor three-level power conversion bridge;

[0039] The output end of the first switch tube is connected to the input end of the second switch tube, and the connection point is connected to one end of the flying capacitor;

[0040] The output end of the second switch tube is connected to the input end of the third switch tube, and the connection point serves as the midpoint of the flying capacitor three-level power conversion bridge;

[0041] The output end of the third switch tube is connected to the input end of the fourth switch tube, and the connection point is connected to the other end of the flying capacitor;

[0042] The output end of the fourth switch tube serves as the negative electrode of the flying capacitor three-level power conversion bridge.

[0043] Optionally, the first switch tube and the second switch tube are controllable, and the third switch tube and the fourth switch tube are not controllable; or,

[0044] The first switch tube and the second switch tube are uncontrollable, and the third switch tube and the fourth switch tube are controllable; or,

[0045] The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all controllable.

[0046] It can be seen from the above technical solution that the utility model provides a flying capacitor three-level DC / DC converter. Under normal circumstances, a flying capacitor three-level power conversion bridge is arranged between the two poles on the high-voltage side of the flying capacitor three-level DC / DC conversion circuit, and one end of the flying capacitor in the flying capacitor three-level power conversion bridge is connected to the positive pole on the high-voltage side of the flying capacitor three-level DC / DC conversion circuit through the diode of the upper tube in the upper half bridge of the flying capacitor three-level power conversion bridge, and the other end of the flying capacitor is connected to the negative pole on the high-voltage side of the flying capacitor three-level DC / DC conversion circuit through the diode of the lower tube of the lower half bridge of the flying capacitor three-level power conversion bridge, so the two ends of the flying capacitor can be connected to the two ends of the discharge circuit, and because the discharge circuit is in a path state when the flying capacitor three-level DC / DC converter stops working, the flying capacitor can be discharged through the discharge circuit at this time, so the present application can make the flying capacitor discharge when the flying capacitor three-level DC / DC converter stops working. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0048] Figure 1-Figure 8 The figures are schematic diagrams of the structures of eight implementation modes of a flying capacitor three-level DC / DC converter provided in the embodiments of the present application. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0050] In this application, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0051] In order to discharge the flying capacitor when the flying capacitor three-level DC / DC converter stops working, the embodiment of the present application provides a flying capacitor three-level DC / DC converter, and its specific structure is as follows: Figure 1 As shown, it specifically includes: a flying capacitor three-level DC / DC conversion circuit 100 and a discharge circuit 200; the connection relationship between each circuit is specifically described as follows:

[0052] The high voltage side of the flying capacitor three-level DC / DC conversion circuit 100 serves as the high voltage side of the flying capacitor three-level DC / DC converter, and the low voltage side of the flying capacitor three-level DC / DC conversion circuit 100 serves as the low voltage side.

[0053] Among them, the high-voltage side of the flying capacitor three-level DC / DC conversion circuit 100 refers to: the side with higher voltage on both sides of the flying capacitor three-level DC / DC conversion circuit 100, and the low-voltage side of the flying capacitor three-level DC / DC conversion circuit 100 refers to: the side with lower voltage on both sides of the flying capacitor three-level DC / DC conversion circuit 100.

[0054] For example, assuming that the flying capacitor three-level DC / DC conversion circuit 100 is a flying capacitor three-level Buck circuit, the high voltage side of the flying capacitor three-level DC / DC conversion circuit 100 refers to: the input side of the flying capacitor three-level Buck circuit, and the low voltage side of the flying capacitor three-level DC / DC conversion circuit 100 refers to: the output side of the flying capacitor three-level Buck circuit.

[0055] For another example, assuming that the flying capacitor three-level DC / DC conversion circuit 100 is a flying capacitor three-level Boost circuit, the high voltage side of the flying capacitor three-level DC / DC conversion circuit 100 refers to: the output side of the flying capacitor three-level Boost circuit, and the low voltage side of the flying capacitor three-level DC / DC conversion circuit 100 refers to: the input side of the flying capacitor three-level Boost circuit.

[0056] Both ends of the discharge circuit 200 are respectively connected to two electrodes on the high voltage side of the flying capacitor three-level DC / DC conversion circuit 100 .

[0057] The discharge circuit 200 is in a conduction state when the flying capacitor three-level DC / DC converter stops working, that is, when the flying capacitor three-level DC / DC converter stops working, current can flow through the discharge circuit 200 .

[0058] The flying capacitor three-level DC / DC conversion circuit 100 specifically includes: at least one flying capacitor three-level power conversion bridge 110, at least one inductor L and two capacitors C1 and C2; the connection relationship between the components is as follows:

[0059] The positive electrode and negative electrode of each flying capacitor three-level power conversion bridge 110 correspond to the positive electrode and negative electrode of the high voltage side of the flying capacitor three-level DC / DC conversion circuit 100, respectively. The midpoint of each flying capacitor three-level power conversion bridge 110 is connected to: one end of the inductor L corresponding to itself. The other end of each inductor L serves as the positive electrode of the low voltage side of the flying capacitor three-level DC / DC conversion circuit 100. The negative electrode of each flying capacitor three-level power conversion bridge 110 serves as the negative electrode of the low voltage side of the flying capacitor three-level DC / DC conversion circuit 100.

[0060] A first capacitor C1 is provided between two electrodes on the high voltage side of the flying capacitor three-level DC / DC converter circuit 100. A second capacitor C2 is provided between two electrodes on the low voltage side of the flying capacitor three-level DC / DC converter circuit 100.

[0061] Taking the flying capacitor three-level DC / DC converter circuit 100 including two flying capacitor three-level power conversion bridges 110 as an example, the specific structure of the flying capacitor three-level DC / DC converter circuit 100 in this case is as follows: Figure 1 As shown, the specific connection relationship between the components is as follows:

[0062] The positive electrodes of the two flying capacitor three-level power conversion bridges 110 are connected, and the connection point serves as the positive electrode of the high voltage side of the flying capacitor three-level DC / DC conversion circuit 100. The negative electrodes of the two flying capacitor three-level power conversion bridges 110 are connected, and the connection points serve as the negative electrode of the high voltage side and the negative electrode of the low voltage side of the flying capacitor three-level DC / DC conversion circuit 100, respectively.

[0063] The midpoints of the two flying capacitor three-level power conversion bridges 110 are respectively connected to one end of the two inductors L. The other ends of the two inductors L are connected, and the connection point serves as the positive electrode of the low voltage side of the flying capacitor three-level DC / DC conversion circuit 100 .

[0064] It should be noted that since the connection relationship between the two capacitors is exactly the same as above, it will not be repeated here.

[0065] See also Figure 1 Each flying capacitor three-level power conversion bridge 110 specifically includes: a flying capacitor Cfly and four switch tubes 111-114; the connection relationship between the components is as follows:

[0066] The input end of the first switch tube 111 serves as the positive electrode of the flying capacitor three-level power conversion bridge 110. The output end of the first switch tube 111 is connected to the input end of the second switch tube 112, and the connection point is connected to one end of the flying capacitor Cfly. The output end of the second switch tube 112 is connected to the input end of the third switch tube 113, and the connection point serves as the midpoint of the flying capacitor three-level power conversion bridge 110. The output end of the third switch tube 113 is connected to the input end of the fourth switch tube 114, and the connection point is connected to the other end of the flying capacitor Cfly. The output end of the fourth switch tube 114 serves as the negative electrode of the flying capacitor three-level power conversion bridge 110.

[0067] The flying capacitor three-level power conversion bridge 110 is divided into an upper half bridge and a lower half bridge with its midpoint as the dividing point, wherein the upper half bridge includes a first switch tube 111 and a second switch tube 112, and the lower half bridge includes a third switch tube 113 and a fourth switch tube 114. In addition, in the upper half bridge, the first switch tube 111 is located at an upper position and the second switch tube 112 is located at a lower position, so the first switch tube 111 is an upper tube and the second switch tube 112 is a lower tube. Similarly, in the lower half bridge, the third switch tube 113 is an upper tube and the fourth switch tube 114 is a lower tube.

[0068] It should be noted that the control strategy for the above four switch tubes is the same as that in the prior art, and will not be described in detail here.

[0069] As can be seen from the above, a flying capacitor three-level power conversion bridge 110 is provided between the two poles on the high voltage side of the flying capacitor three-level DC / DC conversion circuit 100, and one end of the flying capacitor Cfly in the flying capacitor three-level power conversion bridge 110 is connected to the positive pole on the high voltage side of the flying capacitor three-level DC / DC conversion circuit 100 through the diode of the upper tube in the upper half bridge of the flying capacitor three-level power conversion bridge 110, and the other end of the flying capacitor Cfly is connected to the positive pole on the high voltage side of the flying capacitor three-level DC / DC conversion circuit 100 through the lower half bridge of the flying capacitor three-level power conversion bridge 110. The diode of the lower tube is connected to the negative electrode of the high voltage side of the flying capacitor three-level DC / DC converter circuit 100, so the two ends of the flying capacitor Cfly can be connected to the two ends of the discharge circuit 200. Since the discharge circuit 200 is in a pass state when the flying capacitor three-level DC / DC converter stops working, the flying capacitor Cfly can be discharged through the discharge circuit 200 at this time. Therefore, the present application can enable the flying capacitor Cfly to discharge when the flying capacitor three-level DC / DC converter stops working.

[0070] Another embodiment of the present application provides an implementation of a flying capacitor three-level power conversion bridge 110. The specific structure of this implementation is similar to Figure 1 The flying capacitor three-level power conversion bridge 110 shown in the figure has the same implementation mode, and the difference between the two is that: in this implementation mode, the first switch tube 111 and the second switch tube 112 are controllable, and the third switch tube 113 and the fourth switch tube 114 are not controllable.

[0071] In this embodiment, the first switch tube 111 and the second switch tube 112 can both be MOS tubes or IGBTs. In practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to the specific situation and is within the protection scope of this application.

[0072] It should be noted that the MOS tubes or IGBTs mentioned in this embodiment are all provided with anti-parallel diodes.

[0073] In this embodiment, the third switch tube 113 and the fourth switch tube 114 can both be diodes. In practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to the specific situation and is within the protection scope of this application.

[0074] Taking the first switch tube 111 and the second switch tube 112 as MOS tubes, and the third switch tube 113 and the fourth switch tube 114 as diodes as an example, the specific structure of the flying capacitor three-level power conversion bridge 110 is as follows: Figure 2 The specific connection relationship is as follows:

[0075] The input end of the MOS tube as the first switch tube 111 serves as the positive electrode of the flying capacitor three-level power conversion bridge 110. The output end of the MOS tube as the first switch tube 111 is connected to the input end of the MOS tube as the second switch tube 112, and the connection point is connected to one end of the flying capacitor Cfly. The output end of the MOS tube as the second switch tube 112 is connected to the cathode of the diode as the third switch tube 113, and the connection point is the midpoint of the flying capacitor three-level power conversion bridge 110. The anode of the diode as the third switch tube 113 is connected to the cathode of the diode as the fourth switch tube 114, and the connection point is connected to the other end of the flying capacitor Cfly. The anode of the diode as the fourth switch tube 114 serves as the negative electrode of the flying capacitor three-level power conversion bridge 110.

[0076] In this embodiment, since the first switch tube 111 and the second switch tube 112 are controllable, and the third switch tube 113 and the fourth switch tube 114 are not controllable, the flying capacitor three-level DC / DC converter circuit 100 using this implementation is specifically a flying capacitor three-level Buck circuit.

[0077] Another embodiment of the present application provides another implementation of the flying capacitor three-level power conversion bridge 110. The specific structure of this implementation is similar to Figure 1 The flying capacitor three-level power conversion bridge 110 shown in the figure has the same implementation mode, and the difference between the two is that: in this implementation mode, the first switch tube 111 and the second switch tube 112 are not controllable, and the third switch tube 113 and the fourth switch tube 114 are controllable.

[0078] In this embodiment, the first switch tube 111 and the second switch tube 112 can both be diodes. In practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to the specific situation and is within the protection scope of this application.

[0079] In this embodiment, the third switch tube 113 and the fourth switch tube 114 can both be MOS tubes or IGBTs. In practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to the specific situation and is within the protection scope of this application.

[0080] It should be noted that the MOS tubes or IGBTs mentioned in this embodiment are all provided with anti-parallel diodes.

[0081] Taking the first switch tube 111 and the second switch tube 112 as diodes, and the third switch tube 113 and the fourth switch tube 114 as MOS tubes as an example, the specific structure of the flying capacitor three-level power conversion bridge 110 is as follows: Figure 3 The specific connection relationship is as follows:

[0082] The cathode of the diode as the first switch tube 111 serves as the positive electrode of the flying capacitor three-level power conversion bridge 110. The anode of the diode as the first switch tube 111 is connected to the cathode of the diode as the second switch tube 112, and the connection point is connected to one end of the flying capacitor Cfly. The anode of the diode as the second switch tube 112 is connected to the input end of the MOS tube as the third switch tube 113, and the connection point serves as the midpoint of the flying capacitor three-level power conversion bridge 110. The output end of the MOS tube as the third switch tube 113 is connected to the input end of the MOS tube as the fourth switch tube 114, and the connection point is connected to the other end of the flying capacitor Cfly. The output end of the MOS tube as the fourth switch tube 114 serves as the negative electrode of the flying capacitor three-level power conversion bridge 110.

[0083] In this embodiment, since the first switch tube 111 and the second switch tube 112 are uncontrollable, and the third switch tube 113 and the fourth switch tube 114 are controllable, the flying capacitor three-level DC / DC converter circuit 100 using this implementation is specifically a flying capacitor three-level Boost circuit.

[0084] Another embodiment of the present application provides another implementation of the flying capacitor three-level power conversion bridge 110. The specific structure of this implementation is similar to Figure 1 The flying capacitor three-level power conversion bridge 110 shown in the figure has the same implementation mode, and the difference between the two is that in this implementation mode, the first switch tube 111, the second switch tube 112, the third switch tube 113 and the fourth switch tube 114 are all controllable.

[0085] In this embodiment, the first switch tube 111, the second switch tube 112, the third switch tube 113 and the fourth switch tube 114 can all be MOS tubes or IGBTs. In practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to the specific situation. All of them are within the protection scope of this application.

[0086] It should be noted that the MOS tubes or IGBTs mentioned in this embodiment are all provided with anti-parallel diodes.

[0087] Taking the first switch tube 111, the second switch tube 112, the third switch tube 113 and the fourth switch tube 114 as MOS tubes as an example, the specific structure of the flying capacitor three-level power conversion bridge 110 is as follows: Figure 4 The specific connection relationship is as follows:

[0088] The input end of the MOS tube as the first switch tube 111 serves as the positive electrode of the flying capacitor three-level power conversion bridge 110. The output end of the MOS tube as the first switch tube 111 is connected to the input end of the MOS tube as the second switch tube 112, and the connection point is connected to one end of the flying capacitor Cfly. The output end of the MOS tube as the second switch tube 112 is connected to the input end of the MOS tube as the third switch tube 113, and the connection point is the midpoint of the flying capacitor three-level power conversion bridge 110. The output end of the MOS tube as the third switch tube 113 is connected to the input end of the MOS tube as the fourth switch tube 114, and the connection point is connected to the other end of the flying capacitor Cfly. The output end of the MOS tube as the fourth switch tube 114 serves as the negative electrode of the flying capacitor three-level power conversion bridge 110.

[0089] In this embodiment, since the first switch tube 111, the second switch tube 112, the third switch tube 113 and the fourth switch tube 114 are all controllable, if different control strategies are executed on the four switch tubes, the flying capacitor three-level DC / DC conversion circuit 100 using this implementation can be either a flying capacitor three-level Boost circuit or a flying capacitor three-level Boost circuit.

[0090] Another embodiment of the present application provides another implementation of a flying capacitor three-level DC / DC converter, which is applicable to the following situation: each flying capacitor three-level power conversion bridge 110 adopts an implementation in which both the first switch tube 111 and the second switch tube 112 are controllable. The specific structure of this implementation can be seen in Figure 5 ( Figure 5 Only in Figure 4 Based on the above embodiment, this embodiment further includes: a first pre-charging circuit 300; the connection relationship between this circuit and its circuit is as follows:

[0091] The output end of the first pre-charging circuit 300 is connected to the positive electrode of the high voltage side of the flying capacitor three-level DC / DC conversion circuit 100. The input end of the first pre-charging circuit 300 receives the first supply voltage V1. It should be noted that the first supply voltage V1 is set according to actual conditions and is not specifically limited here.

[0092] In a specific example, the input end of the first pre-charging circuit 300 is connected to the positive electrode of the high voltage side of the flying capacitor three-level DC / DC converter, that is, the first supply voltage V1 is equal to the voltage of the high voltage side of the flying capacitor three-level DC / DC converter.

[0093] The above example only shows one implementation of the input end of the first pre-charging circuit 300. In practical applications, including but not limited to this, as long as the input end of the first pre-charging circuit 300 receives the first supply voltage V1, it is within the protection scope of this application and is not specifically limited here.

[0094] When the flying capacitor three-level DC / DC converter does not start working, the first pre-charging circuit 300 is in a conducting state, and the upper tube of the upper half bridge of each flying capacitor three-level power conversion bridge 110 in the flying capacitor three-level DC / DC conversion circuit 100 is turned on. In other words, when the flying capacitor three-level DC / DC converter does not start working, current can flow through the first pre-charging circuit 300 and the upper tube of the upper half bridge of each flying capacitor three-level power conversion bridge 110.

[0095] In addition, when the pre-charging needs to be stopped, the first pre-charging circuit 300 is in an open circuit state. In other words, when the pre-charging needs to be stopped, the current cannot flow through the first pre-charging circuit 300 .

[0096] Since the current can flow through the first pre-charging circuit 300 and the upper tube of the upper half bridge of each flying capacitor three-level power conversion bridge 110 when the flying capacitor three-level DC / DC converter does not start working, it can be deduced from the above description of the structure of the flying capacitor three-level power conversion bridge 110 that when the flying capacitor three-level DC / DC converter does not start working, the pre-charging circuit, the upper tube of the upper half bridge of each flying capacitor three-level power conversion bridge 110, each flying capacitor Cfly, the diode of the upper tube of the lower half bridge of each flying capacitor three-level power conversion bridge 110, and the second capacitor C2 form a loop, and the specific current path is as follows: Figure 5 As shown by the solid line with arrows in FIG. 1 , the implementation method provided in this embodiment can pre-charge each flying capacitor Cfly.

[0097] It is worth noting that, from the above description of the structure of the flying capacitor three-level DC / DC converter circuit 100, it can be seen that the first capacitor C1 is arranged between the two poles of the high voltage side of the flying capacitor three-level DC / DC converter circuit 100. Therefore, while the flying capacitor Cfly is pre-charged, the first capacitor C1 can also be pre-charged, that is, the first capacitor C1 and the flying capacitor Cfly share a pre-charging circuit, so that this embodiment optimizes the structure of the flying capacitor three-level DC / DC converter, thereby reducing the overall cost of the flying capacitor three-level DC / DC converter.

[0098] In addition, since the current cannot flow through the first pre-charging circuit 300 when the pre-charging needs to be stopped, the flying capacitor Cfly cannot be pre-charged at this time; at the same time, the first capacitor C1 is no longer pre-charged.

[0099] Another embodiment of the present application provides a specific implementation of the first pre-charging circuit 300, and its specific structure is as follows: Figure 5 As shown, it specifically includes: a second switch S2 and a second resistor R2; the connection relationship between the components is specifically as follows:

[0100] The second switch S2 and the second resistor R2 are connected in series, and the series branches formed serve as the input end and the output end of the first pre-charging circuit 300 respectively; the control end of the second switch S2 serves as the control end of the first pre-charging circuit 300.

[0101] When the control terminal of the second switch S2 receives a conduction signal, the second switch S2 is turned on, so that the first pre-charging circuit 300 is in a conduction state.

[0102] When the control terminal of the second switch S2 receives a turn-off signal, the second switch S2 is turned off, so that the first pre-charging circuit 300 is in an open circuit state.

[0103] Optionally, the second switch S2 may be a mechanical switch or an electronic switch, which is not specifically limited here and may be determined according to specific circumstances, and is within the protection scope of the present application.

[0104] It should be noted that mechanical switches and mechanical switches are already very mature in the prior art and will not be described in detail here.

[0105] In this embodiment, since only switches and resistors are used, the first pre-charging circuit 300 has a simple structure and low cost, which is conducive to market promotion, thereby optimizing the overall structure of the flying capacitor three-level DC / DC converter and reducing the overall cost of the flying capacitor three-level DC / DC converter.

[0106] Another embodiment of the present application provides another implementation of a flying capacitor three-level DC / DC converter, which is applicable to the following situation: each flying capacitor three-level power conversion bridge 110 adopts an implementation in which both the first switch tube 111 and the second switch tube 112 are controllable. The specific structure of this implementation is as follows Figure 6 As shown, this embodiment, based on the above embodiment, further includes: a second pre-charging circuit 400; the connection relationship between this circuit and its circuit is specifically described as follows:

[0107] The output end of the second pre-charging circuit 400 is connected to the positive electrode of the high voltage side of the flying capacitor three-level DC / DC conversion circuit 100. The input end of the second pre-charging circuit 400 receives the second supply voltage V2. It should be noted that the first supply voltage V1 is set according to actual conditions and is not specifically limited here.

[0108] In a specific example, the input end of the second pre-charging circuit 400 is connected to the positive electrode of the high voltage side of the flying capacitor three-level DC / DC converter, that is, the second supply voltage V2 is equal to the voltage of the high voltage side of the flying capacitor three-level DC / DC converter.

[0109] The above example only shows one implementation of the input end of the second pre-charging circuit 400. In practical applications, including but not limited to this, as long as the input end of the second pre-charging circuit 400 receives the second supply voltage V2, it is within the protection scope of this application and is not specifically limited here.

[0110] When the flying capacitor three-level DC / DC converter does not start working, the second pre-charging circuit 400 is in a conducting state. In other words, when the flying capacitor three-level DC / DC converter does not start working, current can flow through the second pre-charging circuit 400 .

[0111] In addition, when the pre-charging needs to be stopped, the second pre-charging circuit 400 is in an open circuit state. In other words, when the pre-charging needs to be stopped, the current cannot flow through the second pre-charging circuit 400.

[0112] Since current can flow through the second pre-charging circuit 400 when the flying capacitor three-level DC / DC converter does not start working, the second pre-charging circuit 400 and the first pre-charging circuit 300 are in a conductive state at the same time, so that current can flow through the second pre-charging circuit 400 and the first pre-charging circuit 300 at the same time, thereby increasing the current for pre-charging the flying capacitor Cfly, thereby accelerating the pre-charging speed of the flying capacitor Cfly.

[0113] It is worth noting that, from the above description of the structure of the flying capacitor three-level DC / DC converter circuit 100, it can be seen that the first capacitor C1 is arranged between the two poles on the high voltage side of the flying capacitor three-level DC / DC converter circuit 100. Therefore, while the current for pre-charging the flying capacitor Cfly is increased through the second pre-charging circuit 400, the current for pre-charging the first capacitor C1 can also be accelerated.

[0114] In addition, since the current cannot flow through the second pre-charging circuit 400 when the pre-charging needs to be stopped, the second pre-charging circuit 400 and the first pre-charging circuit 300 are both in an open circuit state, so that the flying capacitor Cfly cannot be pre-charged at this time; at the same time, the first capacitor C1 is no longer pre-charged.

[0115] Another embodiment of the present application provides a specific implementation of the second pre-charging circuit 400, and its specific structure is as follows: Figure 6 As shown, it specifically includes: a first switch S1 and a first resistor R1; the connection relationship between the components is specifically as follows:

[0116] The first switch S1 and the first resistor R1 are connected in series, and the series branches formed serve as the input end and the output end of the second pre-charging circuit 400 respectively; the control end of the first switch S1 serves as the control end of the second pre-charging circuit 400.

[0117] When the control terminal of the first switch S1 receives a turn-on signal, the first switch S1 is turned on, so that the second pre-charging circuit 400 is in a conduction state.

[0118] When the control terminal of the first switch S1 receives a turn-off signal, the first switch S1 is turned off, so that the second pre-charging circuit 400 is in an open circuit state.

[0119] Optionally, the first switch S1 may be a mechanical switch or an electronic switch, which is not specifically limited here and may be determined according to specific circumstances, and all are within the protection scope of the present application.

[0120] It should be noted that mechanical switches and mechanical switches are already very mature in the prior art and will not be described in detail here.

[0121] In this embodiment, since only switches and resistors are used, the second pre-charging circuit 400 has a simple structure and low cost, which is conducive to market promotion, thereby optimizing the overall structure of the flying capacitor three-level DC / DC converter and reducing the overall cost of the flying capacitor three-level DC / DC converter.

[0122] Another embodiment of the present application provides another implementation of a flying capacitor three-level DC / DC converter. The specific structure of this implementation can be found in Figure 7 ( Figure 7 Only in Figure 6 This embodiment is based on the above embodiment and further includes: at least two absorption circuits 500; the connection relationship between this device and its devices is as follows:

[0123] An absorption circuit 500 is connected in parallel between the two ends of the upper half bridge of each flying capacitor three-level power conversion bridge 110 in the flying capacitor three-level DC / DC conversion circuit 100. An absorption circuit 500 is connected in parallel between the two ends of the lower half bridge of each flying capacitor three-level power conversion bridge 110.

[0124] It should be noted that the upper half bridge and the lower half bridge have been described in detail in the above embodiments and will not be described again here.

[0125] In this embodiment, the absorption circuit 500 can absorb the voltage peaks and spike interferences of the upper half bridge and the lower half bridge, thereby avoiding the influence of these interferences on other electronic components to a certain extent, thereby protecting other electronic components from damage to a certain extent.

[0126] In addition, the absorption circuit 500 can also absorb the high-frequency electromagnetic waves generated in the flying capacitor three-level DC / DC conversion circuit 100. Therefore, the influence of electromagnetic interference is reduced. Moreover, the absorption circuit 500 can be used as a part of filtering, so high-frequency noise can be filtered out, thereby reducing the radiation interference to other electronic devices.

[0127] Optionally, the absorption circuit 500 may include a capacitor, such as Figure 7 As shown in the capacitor Cs, in practical applications, including but not limited to this, no specific limitation is made here, and it may depend on the specific situation, all of which are within the protection scope of this application.

[0128] Since energy loss can be reduced when a capacitor is used as the absorption circuit 500, the capacitor is used as the preferred embodiment of the absorption circuit 500. In addition, since only the capacitor is used when the capacitor is used as the absorption circuit 500, the absorption circuit 500 has a simple structure and a small volume, so that the absorption circuit 500 is easy to be integrated into electronic equipment and systems and occupies less space.

[0129] Optionally, the capacitor used as the absorption circuit 500 may be a thin film capacitor. In practical applications, this includes but is not limited to this. No specific limitation is made here and it may be determined according to specific circumstances. All of these are within the protection scope of this application.

[0130] Since the film capacitor has low parasitic effects and a long service life, the film capacitor is a preferred embodiment of the capacitor of the absorption circuit 500 .

[0131] Another embodiment of the present application provides a specific implementation of the discharge circuit 200. The specific structure of the discharge circuit 200 can be found in Figure 8 ( Figure 8 Only in Figure 7 The connection relationship between the components is as follows:

[0132] The third switch S3 and the third resistor R3 are connected in series, and the series branches formed therein serve as two ends of the discharge circuit 200 ; the control end of the third switch S3 serves as the control end of the discharge circuit 200 .

[0133] When the control terminal of the third switch S3 receives a turn-on signal, the third switch S3 is turned on, so that the discharge circuit 200 is in a conduction state.

[0134] When the control terminal of the third switch S3 receives a turn-off signal, the third switch S3 is turned off, so that the discharge circuit 200 is in an open circuit state.

[0135] Optionally, the third switch S3 may be a mechanical switch or an electronic switch, which is not specifically limited here and may be determined according to specific circumstances, and is within the protection scope of the present application.

[0136] It should be noted that mechanical switches and mechanical switches are already very mature in the prior art and will not be described in detail here.

[0137] In this embodiment, since only switches and resistors are used, the discharge circuit 200 has a simple structure and low cost, which is conducive to market promotion, thereby optimizing the overall structure of the flying capacitor three-level DC / DC converter and reducing the overall cost of the flying capacitor three-level DC / DC converter.

[0138] For the above description of the disclosed embodiments, the features recorded in each embodiment in this specification can be replaced or combined with each other, so that professional and technical personnel in this field can implement or use this application. The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Although the utility model has been disclosed as above with a preferred embodiment, it is not used to limit the utility model. Any technician familiar with the field can make many possible changes and modifications to the technical solution of the utility model by using the methods and technical contents disclosed above without departing from the scope of the technical solution of the utility model, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the utility model without departing from the content of the technical solution of the utility model still falls within the scope of protection of the technical solution of the utility model.

Claims

1. A flying capacitor three-level DC / DC converter, characterized in that: include: Flying capacitor three-level DC / DC conversion circuit and discharge circuit; wherein: The two ends of the discharge circuit are respectively connected to: the two poles of the high voltage side of the flying capacitor three-level DC / DC conversion circuit; The discharge circuit is in a conduction state when the flying capacitor three-level DC / DC converter stops working.

2. The flying capacitor three-level DC / DC converter according to claim 1, characterized in that: Also includes: The first pre-charge circuit; wherein: The output end of the first pre-charging circuit is connected to: the positive electrode of the high voltage side of the flying capacitor three-level DC / DC conversion circuit; An input end of the first pre-charging circuit receives a first supply voltage; The first pre-charging circuit is in a conducting state when the flying capacitor three-level DC / DC converter does not start working, and the upper tube of the upper half bridge of each flying capacitor three-level power conversion bridge in the flying capacitor three-level DC / DC conversion circuit is turned on when the flying capacitor three-level DC / DC converter does not start working.

3. The flying capacitor three-level DC / DC converter according to claim 2, characterized in that: Also includes: The second pre-charge circuit; wherein: The output end of the second pre-charging circuit is connected to: the positive electrode on the high voltage side of the flying capacitor three-level DC / DC conversion circuit; An input end of the second pre-charging circuit receives a second supply voltage; The second pre-charging circuit is in a conducting state when the flying capacitor three-level DC / DC converter does not start to operate.

4. The flying capacitor three-level DC / DC converter according to claim 3, characterized in that: The second pre-charging circuit comprises: a first switch and a first resistor; wherein: The first switch and the first resistor are connected in series, and the series branches formed are respectively used as the input end and the output end of the second pre-charging circuit; The control end of the first switch serves as the control end of the second pre-charging circuit.

5. The flying capacitor three-level DC / DC converter according to claim 2, characterized in that: The first pre-charging circuit includes: a second switch and a second resistor; wherein: The second switch and the second resistor are connected in series, and the series branches formed are respectively used as the input end and the output end of the first pre-charging circuit; The control end of the second switch serves as the control end of the first pre-charging circuit.

6. The flying capacitor three-level DC / DC converter according to any one of claims 1 to 5, characterized in that: Also includes: At least two absorption circuits; wherein: One of the absorption circuits is connected in parallel between the two ends of the upper half bridge of each flying capacitor three-level power conversion bridge in the flying capacitor three-level DC / DC conversion circuit; An absorption circuit is connected in parallel between the two ends of the lower half bridge of each flying capacitor three-level power conversion bridge.

7. The flying capacitor three-level DC / DC converter according to any one of claims 1 to 5, characterized in that: The discharge circuit comprises: a third switch and a third resistor; wherein: The third switch and the third resistor are connected in series, and the series branches formed are respectively used as two ends of the discharge circuit; The control end of the third switch serves as the control end of the discharge circuit.

8. The flying capacitor three-level DC / DC converter according to any one of claims 1 to 5, characterized in that: The flying capacitor three-level DC / DC conversion circuit comprises: at least one flying capacitor three-level power conversion bridge, at least one inductor and two capacitors; wherein: The positive electrode and the negative electrode of each flying capacitor three-level power conversion bridge respectively correspond to the positive electrode and the negative electrode of the high voltage side of the flying capacitor three-level DC / DC conversion circuit; A first capacitor is provided between two electrodes on the high voltage side of the flying capacitor three-level DC / DC conversion circuit; The midpoint of each flying capacitor three-level power conversion bridge is connected to: one end of the inductor corresponding to itself; The other end of each of the inductors serves as the positive electrode of the low voltage side of the flying capacitor three-level DC / DC conversion circuit; The negative electrode of each flying capacitor three-level power conversion bridge serves as the negative electrode of the low voltage side of the flying capacitor three-level DC / DC conversion circuit; A second capacitor is arranged between two electrodes on the low voltage side of the flying capacitor three-level DC / DC conversion circuit.

9. The flying capacitor three-level DC / DC converter according to claim 8, characterized in that: The flying capacitor three-level power conversion bridge comprises: a flying capacitor and four switch tubes; wherein: The input end of the first switch tube serves as the positive electrode of the flying capacitor three-level power conversion bridge; The output end of the first switch tube is connected to the input end of the second switch tube, and the connection point is connected to one end of the flying capacitor; The output end of the second switch tube is connected to the input end of the third switch tube, and the connection point serves as the midpoint of the flying capacitor three-level power conversion bridge; The output end of the third switch tube is connected to the input end of the fourth switch tube, and the connection point is connected to the other end of the flying capacitor; The output end of the fourth switch tube serves as the negative electrode of the flying capacitor three-level power conversion bridge.

10. The flying capacitor three-level DC / DC converter according to claim 9, characterized in that: The first switch tube and the second switch tube are controllable, and the third switch tube and the fourth switch tube are uncontrollable; or, The first switch tube and the second switch tube are uncontrollable, and the third switch tube and the fourth switch tube are controllable; or, The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all controllable.

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