A direct current (DC) to DC boost circuit with voltage difference compensation

Abstract

The application relates to the field of direct-current boosting circuits, in particular to a direct-current DC / DC boosting circuit adopting voltage difference compensation, which comprises a power supply end, an isolation type DC / DC conversion circuit, a direct supply output side and a boosting output side, wherein the isolation type DC / DC conversion circuit comprises a DC / DC input side and a DC / DC output side; the boosting circuit can complete simultaneous high-efficiency power supply from one super capacitor to two different voltage and power grade pulse loads; the application adds the voltage of the input side to the DC / DC output side of the isolation type DC / DC conversion circuit by controlling the conduction of a thyristor, and the voltage difference compensation of the input side greatly reduces the output voltage and capacity requirement of the DC / DC output side of the isolation type DC / DC conversion circuit, the conversion power and current are greatly reduced, the on-state loss is reduced, and thus the efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of DC boost circuits, and more particularly to a DC / DC boost circuit employing voltage difference compensation. Background Technology

[0002] Currently, loads with pulsed power characteristics are increasingly common, such as mobile digital devices, navigation lights, electric vehicles, and directed energy weapons. These loads are characterized by high peak power but low average power, which places demands on the power output capability of the power supply. Supercapacitors, with their advantages of high power density, fast discharge speed, and long cycle life, are suitable for powering pulsed loads. When the same set of supercapacitors supplies power to pulsed loads of different voltage levels, a DC-DC converter is needed to transform the voltage due to the voltage difference between the supercapacitors and the pulsed loads.

[0003] DC-DC converters can be classified into isolated and non-isolated types based on whether they achieve voltage isolation. In high-voltage and high-power applications, isolated full-bridge DC-DC converters are generally used.

[0004] like Figure 1 As shown, an isolated full-bridge DC-DC converter uses a full-bridge structure on both the primary and secondary sides of the high-frequency transformer. Common full-bridge structures include the H-bridge and NPC / H-bridge structures. The H-bridge structure has a simple circuit and fewer switching transistors, but each transistor bears the voltage stress of its corresponding DC bus voltage, which is limited by the voltage rating of the transistor. Furthermore, high-voltage transistors suffer from high switching losses and low switching frequencies, thus limiting the performance and efficiency of the converter. Therefore, existing isolated DC-DC converters used in high-voltage scenarios often employ an NPC / H-bridge structure on the primary side of the high-frequency transformer and a bridge rectifier circuit on the secondary side. This structure also faces some challenges. For high-power DC / DC circuits, firstly, the input voltage on the left side cannot be too high due to the limitations of the transistor voltage rating and switching frequency; secondly, if the output boost ratio on the right side is too large, the conduction losses will increase significantly due to the large number of transistors and high current on the low-voltage input side, resulting in a significant decrease in the conversion circuit efficiency. Summary of the Invention

[0005] To address the problems existing in the prior art, this application provides a DC / DC boost circuit that employs voltage difference compensation.

[0006] A DC / DC boost circuit with voltage difference compensation includes: a power supply terminal, an isolated DC / DC converter circuit, a direct power supply output side, and a boost output side, wherein...

[0007] The isolated DC / DC converter circuit includes a DC / DC input side and a DC / DC output side;

[0008] The positive pole of the power supply end is connected to the positive pole of the DC / DC input side, the negative pole of the power supply end is connected to the negative pole of the DC / DC input side, the positive pole of the DC / DC output side is connected to the inductor, the diode and the positive pole of the boost output side in sequence, and the negative pole of the DC / DC output side is connected to the diode and the negative pole of the boost output side in sequence, so as to realize power supply after DC / DC conversion to supply power to the load connected to the boost output side;

[0009] In addition, the positive pole of the power supply end is further connected to the positive pole of the direct supply output side, the thyristor and the negative pole of the DC / DC output side in sequence, and the negative pole of the power supply end is further connected to the negative pole of the direct supply output side and the negative pole of the boost output side in sequence, so as to realize power supply to the load connected to the direct supply output side and realize power supply and isolation type DC / DC conversion circuit to the load connected to the boost output side at the same time.

[0010] Further, the isolation type DC / DC conversion circuit comprises two NPC / H bridge five-level inverter circuits, two high-frequency transformers and two bridge rectifier circuits. The NPC / H bridge five-level inverter circuit, the high-frequency transformer and the bridge rectifier circuit are connected one by one in correspondence. The positive output side of the NPC / H bridge five-level inverter circuit is connected to the positive input side of the high-frequency transformer, the negative output side of the NPC / H bridge five-level inverter circuit is connected to the negative input side of the high-frequency transformer, the positive output side of the high-frequency transformer is connected to the positive input side of the bridge rectifier circuit, and the negative output side of the high-frequency transformer is connected to the negative input side of the bridge rectifier circuit.

[0011] Further, the positive input side of one of the NPC / H bridge five-level inverter circuits is the positive pole of the DC / DC input side, the negative input side is connected to the positive input side of the other NPC / H bridge five-level inverter circuit, and the negative input side of the other NPC / H bridge five-level inverter circuit is the negative pole of the DC / DC input side.

[0012] Further, the positive output side of one of the bridge rectifier circuits is the positive pole of the DC / DC output side, the negative output side is connected to the positive output side of the other bridge rectifier circuit, and the negative output side of the other bridge rectifier circuit is the negative pole of the DC / DC output side.

[0013] Further, the NPC / H bridge five-level inverter circuit comprises eight switching tubes, four switching tubes are connected in series in each group, and each switching tube is connected in reverse parallel with a diode; two switching tubes in the middle of each group of switching tubes are connected in reverse parallel with two clamping diodes; the connection node in the middle of one group of switching tubes is connected to the positive input side of the high-frequency transformer, and the connection node in the middle of the other group of switching tubes is connected to the negative input side of the high-frequency transformer.

[0014] Further, the NPC / H-bridge five-level inverter circuit further comprises two series-connected bus capacitors, and both groups of switching tubes are connected in parallel with the two bus capacitors.

[0015] Further, a connection node between the two clamping diodes is connected with a connection node between the two bus capacitors.

[0016] Further, the bridge rectifier circuit comprises four rectifier diodes, and each two rectifier diodes are connected in series to form a group, wherein a connection node in one group of rectifier diodes is connected with a positive output of the high-frequency transformer, a connection node in the other group of rectifier diodes is connected with a negative output of the high-frequency transformer, and the two groups of rectifier diodes are connected in parallel with each other and the connection node serves as an output side of the bridge rectifier circuit.

[0017] Further, the bridge rectifier circuit further comprises a filter capacitor, and the two groups of rectifier diodes are connected in parallel with the filter capacitor.

[0018] Technical effects and advantages of the present application:

[0019] The boost circuit of the present application can complete simultaneous efficient power supply from one super capacitor to two different voltage and power level pulse loads;

[0020] The present application controls the conduction of the thyristor, adds the voltage at the input side to the DC / DC output side of the isolation type DC / DC conversion circuit, and uses the voltage difference at the input side for compensation, so as to greatly reduce the output voltage and capacity requirements of the DC / DC output side of the isolation type DC / DC conversion circuit, greatly reduce the conversion power and current, and reduce the on-state loss, thereby improving the efficiency;

[0021] The series connection of the input ends of the two NPC / H-bridge five-level inverter circuits at the DC / DC input side of the isolation type DC / DC conversion circuit can reduce the voltage stress of the switching tube and reduce the switching loss.

[0022] The bridge rectifier circuit composed of diodes is adopted at the DC / DC output side of the isolation type DC / DC conversion circuit, and compared with the multi-level rectifier circuit adopting switching tubes, the device cost is greatly reduced.

[0023] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the structures indicated in the specification and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A prior art full-bridge NPC / H-bridge five-level DC / DC converter circuit diagram is shown;

[0025] Figure 2A topological structure diagram of a DC / DC step-up circuit with voltage difference compensation is shown.

[0026] Figure 3 A circuit diagram of a DC / DC step-up circuit with voltage difference compensation is shown. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0028] In addition, in the application, the terms "first", "second", and other similar terms do not imply any order, quantity, and importance, but are only used to distinguish different elements, and the terms "upper", "lower", "left", "right", and other similar terms are only the positional relationship in the drawings.

[0029] As Figure 2 shown, one embodiment of the present application provides a DC / DC step-up circuit with voltage difference compensation, comprising a power supply end, an isolation type DC / DC conversion circuit, a direct supply output side, and a step-up output side, wherein the isolation type DC / DC conversion circuit comprises a DC / DC input side and a DC / DC output side.

[0030] The positive electrode of the power supply end is connected to the positive electrode of the DC / DC input side, the negative electrode of the power supply end is connected to the negative electrode of the DC / DC input side, the positive electrode of the DC / DC output side is connected to an inductor, a diode, and the positive electrode of the step-up output side in sequence, the negative electrode of the DC / DC output side is connected to a diode and the negative electrode of the step-up output side in sequence, and the positive electrode of the power supply end is further connected to the positive electrode of the direct supply output side, a thyristor, and the negative electrode of the DC / DC output side in sequence, and the negative electrode of the power supply end is further connected to the negative electrode of the direct supply output side and the negative electrode of the step-up output side in sequence.

[0031] As Figure 2 shown, in one specific embodiment of the present application, a super capacitor is used as a power supply and connected to the power supply end; a pulse load 1 is connected to the direct supply output side, and a pulse load 2 is connected to the step-up output side, so that the super capacitor supplies power to the pulse load 1 and the pulse load 2.

[0032] The isolated DC / DC conversion circuit comprises two NPC / H bridge five-level inverter circuits, two high-frequency transformers and two bridge rectifier circuits; the NPC / H bridge five-level inverter circuit, the high-frequency transformer and the bridge rectifier circuit are connected in one-to-one correspondence; the positive output side of the NPC / H bridge five-level inverter circuit is connected to the positive input side of the high-frequency transformer; the negative output side of the NPC / H bridge five-level inverter circuit is connected to the negative input side of the high-frequency transformer; the positive output side of the high-frequency transformer is connected to the positive input side of the bridge rectifier circuit; and the negative output side of the high-frequency transformer is connected to the negative input side of the bridge rectifier circuit.

[0033] The positive input side of one of the NPC / H bridge five-level inverter circuits serves as the positive pole of the DC / DC input side; the negative input side is connected to the positive input side of the other NPC / H bridge five-level inverter circuit; and the negative input side of the other NPC / H bridge five-level inverter circuit serves as the negative pole of the DC / DC input side.

[0034] The positive output side of one of the bridge rectifier circuits serves as the positive pole of the DC / DC output side; the negative output side is connected to the positive output side of the other bridge rectifier circuit; and the negative output side of the other bridge rectifier circuit serves as the negative pole of the DC / DC output side.

[0035] In this way, the circuit can meet the requirement that one super capacitor supplies power to two loads at the same time. Meanwhile, by controlling the conduction of the thyristor VT, the voltage of the super capacitor is added to the DC / DC output side of the isolated DC / DC conversion circuit, and the voltage difference of the DC / DC input side is used for compensation, so that the output voltage and capacity requirement of the DC / DC output side of the isolated DC / DC conversion circuit are greatly reduced, the conversion power and current are greatly reduced, the on-state loss is reduced, and thus the overall efficiency is improved.

[0036] As shown in FIG. 1, Figure 3 In an embodiment of the present application, the NPC / H bridge five-level inverter circuit comprises eight switching tubes and two series bus capacitors; every four switching tubes are connected in series to form a group; each switching tube is connected in anti-parallel with a diode; the two groups of series switching tubes are connected in parallel with the two bus capacitors, and the connection nodes of the switching tubes and the bus capacitors serve as the positive input side and the negative input side of the NPC / H bridge five-level inverter circuit respectively; the two switching tubes in the middle of each group of switching tubes are connected in anti-parallel with two clamping diodes; the connection node between the two clamping diodes is connected to the connection node between the two bus capacitors; the connection node in the middle of one group of switching tubes is connected to the positive input side of the high-frequency transformer; and the connection node in the middle of the other group of switching tubes is connected to the negative input side of the high-frequency transformer.

[0037] As shown in FIG. 2, Figure 3As shown, in one embodiment of the present application, the bridge rectifier circuit includes four rectifier diodes, each two rectifier diodes in series as a group, two groups of rectifier diodes are connected in parallel with a filter capacitor, the connection node in one group of rectifier diodes is connected with the positive output of the high-frequency transformer, the connection node in the other group of rectifier diodes is connected with the negative output of the high-frequency transformer, and the connection node between the rectifier diode and the filter capacitor is the output side of the bridge rectifier circuit.

[0038] As a specific implementation of the present application, the power supply end is connected with a super capacitor, the direct supply output side and the step-up output side are connected with pulse load 1 and pulse load 2 respectively, and the voltage across the super capacitor is V1. The voltage across the pulse load 1 is the same as the voltage across the super capacitor, and the pulse load 1 is directly supplied with power by the super capacitor through the direct supply output side. At the same time, the super capacitor supplies power to the pulse load 2 through the step-up output side in the DC step-up circuit. The rated voltage across the pulse load 2 is V2, and V2 is greater than V1.

[0039] As shown, Figure 3 The power output of the power supply is divided into three paths:

[0040] Path one, the power supply directly supplies power to the pulse load 1;

[0041] Path two, the thyristor VT1 is turned off, and the power supply supplies power to the pulse load 2 after being transformed by the isolation type DC / DC conversion circuit;

[0042] Path three, the thyristor VT1 is turned on, and the positive and negative electrodes of the power supply are connected into the power supply circuit of the load 2 through the DC / DC output side, at this time, the voltage across the pulse load 2 = the DC / DC output side voltage + the power supply voltage.

[0043] In this way, the power supply situation of the power supply can be divided into two stages:

[0044] Stage one, when the voltage demand V2 of the pulse load 2 is lower than the power supply voltage V1, the thyristor VT1 is in the off state, the power supply is discharged and is subjected to step-down transformation by the isolation type DC / DC conversion circuit, and the output current flows from the positive electrode of the DC / DC output side of the isolation type DC / DC conversion circuit to the pulse load 2 through the inductor L1 and the diode D25, and then flows to the P point through the diode D26 and returns to the negative electrode of the DC / DC output side of the isolation type DC / DC conversion circuit;

[0045] Stage two, when the voltage demand V2 of the pulse load 2 is equal to the power supply voltage V1, the isolation type DC / DC conversion circuit is locked at this time, the thyristor VT1 is turned on, and the power supply directly supplies power to the pulse load 2;

[0046] In the third stage, when the voltage requirement V2 of the pulse load 2 is higher than the power supply voltage V1, the thyristor VT1 keeps in the conducting state, the super capacitor discharges and the voltage is converted through the isolation DC / DC conversion circuit, and because the thyristor VT1 is in the conducting state, the basic voltage V1 is formed between the points P and Q, and at this time, the voltage across the pulse load 2 is equal to the output voltage of the DC / DC conversion circuit plus the power supply voltage;

[0047] That is, when V2>V1, the voltage provided by the isolation DC / DC conversion circuit is V2-V1, and compared with the power supply directly supplying power to the pulse load through the isolation DC / DC conversion circuit, the conversion power requirement of the isolation DC / DC conversion circuit is lower.

[0048] For example, when the voltage requirement V2 of the pulse load 2 is 1200V and the power supply voltage V1 is 720V, when the thyristor VT1 is in the conducting state, the isolation DC / DC conversion circuit only needs to convert the 720V voltage into 480V voltage;

[0049] When the voltage requirement V2 of the pulse load 2 is 1200V and the power supply voltage V1 is 720V, when the thyristor VT1 is in the conducting state, the isolation DC / DC conversion circuit only needs to convert the 720V voltage into 480V voltage;

[0050] It should be noted that the conducting and non-conducting states of the thyristor VT1 are realized through an additional control circuit, and the control of the conducting and non-conducting states of the thyristor VT1 by the control circuit is common knowledge in the art, and will not be described in detail here.

[0051] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application, and although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A direct current (DC) / DC boost circuit employing voltage difference compensation, characterized by, The application relates to an isolated DC / DC conversion circuit and a power supply device. The isolated DC / DC conversion circuit comprises a DC / DC input side and a DC / DC output side. The positive pole of the power supply end is connected to the positive pole of the DC / DC input side, the negative pole of the power supply end is connected to the negative pole of the DC / DC input side, the positive pole of the DC / DC output side is connected to an inductor, a diode and the positive pole of the step-up output side in sequence, and the negative pole of the DC / DC output side is connected to the diode and the negative pole of the step-up output side in sequence, so that the power supply is connected to the load at the step-up output side after DC / DC conversion. The positive pole of the power supply end is further connected to the positive pole of the direct supply output side, a thyristor and the negative pole of the DC / DC output side in sequence, and the negative pole of the power supply end is further connected to the negative pole of the direct supply output side and the negative pole of the step-up output side in sequence, so that the power supply is connected to the load at the direct supply output side and the power supply and the isolated DC / DC conversion circuit are simultaneously connected to the load at the step-up output side. The isolated DC / DC conversion circuit comprises two NPC / H bridge five-level inverter circuits, two high-frequency transformers and two bridge rectifier circuits.

2. A DC / DC boost circuit employing voltage difference compensation according to claim 1, characterized in that, The NPC / H bridge five-level inverter circuit, the high-frequency transformer and the bridge rectifier circuit are connected in one-to-one correspondence.

3. A DC / DC boost circuit employing voltage difference compensation according to claim 2, characterized in that, The positive output side of the NPC / H bridge five-level inverter circuit is connected to the positive input side of the high-frequency transformer, the negative output side of the NPC / H bridge five-level inverter circuit is connected to the negative input side of the high-frequency transformer, the positive output side of the high-frequency transformer is connected to the positive input side of the bridge rectifier circuit, and the negative output side of the high-frequency transformer is connected to the negative input side of the bridge rectifier circuit.

4. A DC / DC boost circuit employing voltage difference compensation according to claim 3, characterized in that, The positive input side of one of the NPC / H bridge five-level inverter circuits is used as the positive pole of the DC / DC input side, the negative input side is connected to the positive input side of the other NPC / H bridge five-level inverter circuit, and the negative input side of the other NPC / H bridge five-level inverter circuit is used as the negative pole of the DC / DC input side.

5. A DC / DC boost circuit employing voltage difference compensation according to claim 2, characterized in that, The positive output side of one of the bridge rectifier circuits is used as the positive pole of the DC / DC output side, the negative output side is connected to the positive output side of the other bridge rectifier circuit, and the negative output side of the other bridge rectifier circuit is used as the negative pole of the DC / DC output side.

6. A DC / DC boost circuit employing voltage difference compensation according to claim 5, characterized in that, The NPC / H bridge five-level inverter circuit comprises eight switching tubes, four switching tubes are connected in series in each group, and each switching tube is connected in reverse parallel with a diode.

7. A DC / DC boost circuit employing voltage difference compensation according to claim 6, characterized in that, The two groups of switching tubes are connected in parallel with two bus capacitors. The connection node between the two clamping diodes is connected to the connection node between the two bus capacitors.

8. A DC / DC boost circuit employing voltage difference compensation according to claim 2, characterized by, The bridge rectifier circuit comprises four rectifier diodes, each two rectifier diodes are connected in series as a group, the connection node in one group of rectifier diodes is connected with the positive output of the high-frequency transformer, the connection node in the other group of rectifier diodes is connected with the negative output of the high-frequency transformer, and the two groups of rectifier diodes are connected in parallel with each other and the connection node is used as the output side of the bridge rectifier circuit.

9. A DC / DC boost circuit employing voltage difference compensation according to claim 8, characterized in that, The bridge rectifier circuit further comprises a filter capacitor, and the two groups of rectifier diodes are connected in parallel with the filter capacitor at the same time.

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