DC conversion circuit

Abstract

The present invention discloses a direct current conversion circuit, including a power input terminal, an output interface, a DC-DC converter, a safety switch circuit and a clamping circuit. The input terminal of the DC-DC converter is connected to the power input terminal, and is used to convert the connected power supply voltage and output it. The input terminal of the safety switch circuit is connected to the output terminal of the DC-DC converter, and the output terminal of the safety switch circuit is connected to the output interface, and is used to output the voltage output by the DC-DC converter to the output interface, and is disconnected when the positive and negative poles of the battery and the output interface are reversed. The clamping circuit is used to absorb the voltage spike signal generated when the DC-DC converter is working and store energy, and to supply power to the safety switch circuit, and the safety switch circuit receives the energy storage voltage of the clamping circuit to work. The present invention supplies power to the safety switch circuit through the energy storage of the clamping circuit, and the circuit structure is simpler. The problems of complex DC conversion circuits and energy waste in circuits are solved.

Description

Technical Field

[0001] The invention relates to the field of power electronics, and in particular to a direct current conversion circuit. Background Art

[0002] The hard-bridge DCDC converter is one of the mainstream topologies in battery power applications. In a battery power supply, when the current is relatively large or the efficiency requirement is relatively high, a safety switch MOS tube needs to be connected in series at the output end to prevent reverse connection. The drive of the MOS tube requires power supply, so it is necessary to add an auxiliary source output to power the MOS tube, which increases the complexity of the circuit. In addition, the synchronous rectifier tube on the secondary side of the hard-bridge DCDC converter will generate a large voltage stress during shutdown. In order to solve this stress problem, an embedded capacitor is generally added. The energy of the embedded capacitor is generally consumed by a dummy load, which will cause energy waste. Summary of the invention

[0003] The main purpose of the present invention is to provide a DC conversion circuit, aiming to simplify the circuit structure and avoid energy waste.

[0004] To achieve the above object, the present invention provides a DC conversion circuit, the DC conversion circuit comprising:

[0005] A power input terminal, and the power output terminal is used to connect to a power source;

[0006] An output interface, the output interface being used to connect to a battery;

[0007] A DC-DC converter, wherein an input terminal of the DC-DC converter is connected to the power input terminal;

[0008] The DC-DC converter is used to convert the connected power supply voltage and then output it;

[0009] A safety switch circuit, wherein a first input end of the safety switch circuit is connected to an output end of the DC-DC converter, and an output end of the safety switch circuit is connected to the output interface;

[0010] The safety switch circuit is used to be turned on when the battery is normally connected to the output interface, output the voltage output by the DC-DC converter to the output interface, and to be turned off when the positive and negative poles of the battery and the output interface are reversely connected;

[0011] A clamping circuit, wherein an input end of the clamping circuit is connected to the DC-DC converter, and an output end of the clamping circuit is connected to a second input end of the safety switch circuit;

[0012] The clamping circuit is used to absorb the voltage spike signal generated when the DC-DC converter is working and store energy, and to supply power to the safety switch circuit. The safety switch circuit receives the energy storage voltage of the clamping circuit to work.

[0013] In one embodiment, the safety switch circuit includes a drive circuit and a safety switch;

[0014] The input end of the driving circuit is connected to the output end of the clamping circuit, the driving circuit receives the energy storage voltage of the clamping circuit to work, and the output end of the driving circuit is connected to the controlled end of the safety switch;

[0015] The input end of the safety switch is connected to the output end of the DC-DC converter, and the output end of the safety switch is connected to the output interface. The safety switch is used to be turned on under the control of the drive circuit to output the voltage output by the DC-DC converter to the output interface. The safety switch is also used to be disconnected when the positive and negative poles of the battery and the output interface are reversely connected.

[0016] In one embodiment, the DC conversion circuit further includes a filter circuit;

[0017] The input end of the filter circuit is connected to the output end of the DC-DC converter, the output end of the filter circuit is connected to the safety switch tube circuit, and the filter circuit is used to filter the voltage output by the DC-DC converter.

[0018] In one embodiment, the filter circuit includes a first inductor and a first capacitor;

[0019] The input end of the first inductor is connected to the third end of the secondary side of the transformer, the output end of the first inductor is connected to the input end of the safety switch, the first end of the first capacitor is connected to the DC-DC converter, and the second end of the first capacitor is connected to both the output end of the first inductor and the input end of the safety switch.

[0020] In one embodiment, the DC-DC converter includes a transformer, a first H-bridge circuit and a second H-bridge circuit;

[0021] The primary side of the transformer has a first end and a second end, the secondary side of the transformer has a first end, a second end and a third end, the third end of the secondary side of the transformer is located between the first end and the second end of the secondary side of the transformer, and the third end of the secondary side of the transformer is connected to the input end of the safety switch circuit;

[0022] The first H-bridge circuit has a first end and a second end, the first end of the first H-bridge circuit is connected to the first end of the primary side of the transformer, and the second end of the first H-bridge circuit is connected to the second end of the primary side of the transformer; the first H-bridge circuit is used to output the input power supply voltage to the transformer for voltage conversion;

[0023] The second H-bridge circuit has a first end and a second end, the first end of the second H-bridge circuit is connected to the first end of the secondary side of the transformer, and the second end of the second H-bridge circuit is connected to the second end of the secondary side of the transformer; the second H-bridge circuit is also connected to the clamping circuit; the second H-bridge circuit is used to synchronously rectify and clamp the voltage output by the transformer.

[0024] In one embodiment, the first H-bridge circuit includes a first switch tube, a second switch tube, a third switch tube and a fourth switch tube;

[0025] The input end of the first switch tube is connected to the output end of the second switch tube to form a first end of the first H-bridge circuit, the output end of the first switch tube is connected to the positive electrode of the power input interface and the output end of the third switch tube, and the input end of the second switch tube is connected to the negative electrode of the power input interface and the input end of the fourth switch tube;

[0026] The input end of the third switch tube is connected to the output end of the fourth switch tube to form the second end of the first H-bridge circuit.

[0027] In one embodiment, the second H-bridge circuit includes a fifth switch tube, a sixth switch tube, a seventh switch tube and an eighth switch tube;

[0028] The input end of the fifth switch tube is connected to the output end of the sixth switch tube to form the first end of the second H-bridge circuit, the output end of the fifth switch tube is connected to the output end of the seventh switch tube and the clamping circuit, and the input end of the sixth switch tube is connected to the input end of the eighth switch tube and the clamping circuit;

[0029] The input end of the seventh switch tube is connected to the output end of the eighth switch tube to form the second end of the second H-bridge circuit;

[0030] The fifth switch tube and the seventh switch tube are used to clamp the voltage output by the transformer, and the sixth switch tube and the eighth switch tube are used to synchronously rectify the voltage output by the transformer.

[0031] In one embodiment, the clamping circuit includes a second capacitor;

[0032] The first end of the second capacitor is connected to the output end of the fifth switch tube and the input end of the safety switch circuit, and the second end of the second capacitor is grounded. The second capacitor is used to absorb the voltage spike signal generated when the second H-bridge circuit is working and store energy, and supply power to the safety switch circuit.

[0033] In one embodiment, the DC conversion circuit further includes a step-down voltage stabilization circuit;

[0034] The step-down and voltage-stabilizing circuit is connected to the output end of the clamping circuit, and is used for stepping down and stabilizing the voltage output by the clamping circuit and then outputting it to the safety switch circuit.

[0035] In one embodiment, the step-down voltage stabilization circuit includes a first resistor and a voltage stabilization diode;

[0036] The input end of the first resistor is connected to the clamping circuit, the output end of the first resistor is connected to the driving circuit, and the voltage regulator diode is connected in parallel to the driving circuit.

[0037] The present invention supplies power to the safety switch circuit through the energy storage of the clamp circuit, eliminating the extra load that consumes the energy of the clamp circuit and the auxiliary source circuit that supplies power to the safety switch circuit, making the circuit structure simpler, effectively reducing the cost and avoiding energy waste, and solving the problem of complex DC conversion circuit and energy waste in the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention 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 described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0039] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0040] Figure 2 It is a structural schematic diagram of an embodiment of the present invention;

[0041] Figure 3 FIG. 1 is a schematic diagram of a circuit structure of an embodiment of the present invention.

[0042] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0045] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0046] Reference Figure 1 The present invention provides a DC conversion circuit, which includes a power input terminal 10, a DC-DC converter 20, a clamping circuit 30, a safety switch circuit 40, the clamping circuit 30 and an output interface 50.

[0047] The power output terminal is used to connect to the power supply.

[0048] The output interface 50 is used to connect to a battery.

[0049] The input end of the DC-DC converter 20 is connected to the power input end 10 ; the DC-DC converter 20 is used to convert the input power supply voltage and then output it.

[0050] The first input end of the safety switch circuit 40 is connected to the output end of the DC-DC converter 20, and the output end of the safety switch circuit 40 is connected to the output interface 50; the safety switch circuit 40 is used to be turned on when the battery is normally connected to the output interface 50, output the voltage output by the DC-DC converter 20 to the output interface 50, and disconnected when the positive and negative poles of the battery and the output interface 50 are reversed.

[0051] The input end of the clamp circuit 30 is connected to the DC-DC converter 20, and the output end of the clamp circuit 30 is connected to the second input end of the safety switch circuit 40; the clamp circuit 30 is used to absorb the voltage spike signal generated when the DC-DC converter 20 is working and store energy, and to supply power to the safety switch circuit 40. The safety switch circuit 40 receives the energy storage voltage of the clamp circuit 30 to work.

[0052] The primary side of the DC-DC converter 20 is a hard-switching full-bridge circuit. There is no inductance in the hard-switching full-bridge circuit, and the current changes very quickly. When the synchronous rectifier in the DC-DC converter 20 stops working suddenly, a large voltage spike signal will be generated on the secondary side, damaging the DC-DC converter 20. Therefore, the voltage spike signal is generally absorbed by connecting a clamp circuit 30 in parallel on the secondary side, and an additional load is also required to consume the energy absorbed by the clamp circuit 30, which will cause energy waste. The drive of the safety switch circuit 40 in the DC conversion circuit requires power supply. Generally, an auxiliary source circuit is designed in the circuit to supply power to the safety switch circuit 40, but this increases the complexity of the circuit design.

[0053] To solve the above problems, the present invention optimizes the existing DC conversion circuit, and uses the voltage spike signal absorbed by the clamp circuit 30 to power the safety switch circuit 40. The clamp circuit 30 absorbs the spike voltage signal generated when the DC-DC converter 20 is working and stores energy, and then supplies power to the safety switch circuit 40 to drive the safety switch circuit 40 to work.

[0054] The present invention supplies power to the safety switch circuit through the energy storage of the clamp circuit 30, eliminating the additional load that consumes the energy of the clamp circuit 30 and the auxiliary source circuit that supplies power to the safety switch circuit, making the circuit structure simpler, effectively reducing the cost and avoiding energy waste. The problem of complex DC conversion circuit and energy waste in the circuit is solved.

[0055] In one embodiment, the safety switch circuit 40 includes a driving circuit 41 and a safety switch 42 .

[0056] The input end of the driving circuit 41 is connected to the output end of the clamping circuit 30, the driving circuit 41 receives the energy storage voltage of the clamping circuit 30 to work, and the output end of the driving circuit 41 is connected to the controlled end of the safety switch 42;

[0057] The input end of the safety switch 42 is connected to the output end of the DC-DC converter 20, and the output end of the safety switch 42 is connected to the output interface 50. The safety switch 42 is used to be turned on under the control of the drive circuit 41 to output the voltage output by the DC-DC converter 20 to the output interface 50. The safety switch 42 is also used to be disconnected when the positive and negative poles of the battery and the output interface 50 are reversed.

[0058] In the above embodiment, the safety switch 42 may be a PMOS tube. Since there is a body diode in the PMOS tube that conducts unidirectionally from the input end of the safety switch 42 to the output end of the safety switch 42, when the battery is reversely connected to the output interface 50, the body diode in the PMOS tube is cut off, thereby preventing the battery from being reversely connected and damaging the DC conversion circuit.

[0059] The clamp circuit 30 absorbs the voltage spike signal of the DC-DC converter 20 and stores energy to supply power to the drive circuit 41. The drive circuit 41 outputs a PWM signal to the safety switch 42 to control the safety switch 42 to conduct, and outputs the voltage output by the DC-DC converter 20 to the output interface 50 to supply power to the battery.

[0060] In one embodiment, the DC conversion circuit further includes a filter circuit 60 .

[0061] The input end of the filter circuit 60 is connected to the output end of the DC-DC converter 20 , and the output end of the filter circuit 60 is connected to the safety switch 42 . The filter circuit 60 is used to filter the voltage output by the DC-DC converter 20 .

[0062] In this embodiment, the filter circuit 60 is used to filter out the AC interference signal in the DC voltage signal output by the DC-DC converter 20 to obtain a relatively pure DC voltage signal, thereby effectively suppressing signal interference.

[0063] In one embodiment, the filter circuit 60 includes a first inductor L1 and a first capacitor C1.

[0064] The input end of the first inductor L1 is connected to the third end of the secondary side of the transformer 21, the output end of the first inductor L1 is connected to the input end of the safety switch 42, the first end of the first capacitor C1 is connected to the DC-DC converter 20, and the second end of the first capacitor C1 is connected to both the output end of the first inductor L1 and the input end of the safety switch 42.

[0065] In this embodiment, the first inductor L1 absorbs most of the AC interference signal and converts it into magnetic energy and heat energy. The first capacitor C1 filters out the remaining AC interference signal to output a relatively pure DC voltage signal.

[0066] In one embodiment, the safety switch circuit 40 further includes a current detection circuit.

[0067] The input end of the current detection circuit is connected to the output end of the first inductor L1. The current detection circuit is used to detect the current output by the first inductor L1, and output a first detection signal when the current value output by the first inductor L1 is greater than or equal to a preset current value, and output a second detection signal when the current value output by the first inductor L1 is less than the preset current value.

[0068] The driving circuit 41 also has a detection end, which is connected to the output end of the current detection circuit. The driving circuit 41 is used to control the safety switch 42 to open according to the first detection signal, and to control the safety switch 42 to close according to the second control signal.

[0069] When the power of the battery is low, the current of the first inductor L1 is in a discontinuous state, and the current detection circuit detects that the current value output by the first inductor L1 is less than the preset current value, and outputs a first detection signal to the drive circuit 41. The drive circuit 41 outputs a corresponding PWM signal to control the safety switch 42 to disconnect, and the DC-DC converter 20 supplies power to the battery through the body diode in the safety switch 42 to prevent the current from flowing back when the current in the discontinuous state is zero.

[0070] When the power of the battery is relatively large, the current of the first inductor L1 is in a continuous state, the current detection circuit detects that the current value output by the first inductor L1 is greater than or equal to the preset current value, and outputs a second detection signal to the drive circuit 41. The power consumption of the current passing through the MOS tube is less than the power consumption of the current passing through the body diode, the drive circuit 41 outputs a corresponding PWM signal to control the safety switch 42 to turn on, and the DC-DC converter 20 supplies power to the battery through the MOS tube in the safety switch 42.

[0071] In this embodiment, the driving circuit 41 controls the safety switch 42 to be opened when the current of the first inductor L1 is in a discontinuous state, and closed when the current of the first inductor L1 is in a continuous state, so as to prevent the current backflow of the battery from damaging the DC conversion circuit.

[0072] In one embodiment, the DC-DC converter 20 includes a transformer 21 , a first H-bridge circuit 22 , and a second H-bridge circuit 23 .

[0073] The primary side of the transformer 21 has a first end and a second end, the secondary side of the transformer 21 has a first end, a second end and a third end, the third end of the secondary side of the transformer 21 is located between the first end and the second end of the secondary side of the transformer 21, and the third end of the secondary side of the transformer 21 is connected to the input end of the safety switch circuit 40.

[0074] The first H-bridge circuit 22 has a first end and a second end. The first end of the first H-bridge circuit 22 is connected to the first end of the primary side of the transformer 21, and the second end of the first H-bridge circuit 22 is connected to the second end of the primary side of the transformer 21. The first H-bridge circuit 22 is used to output the input power supply voltage to the transformer 21 for voltage conversion.

[0075] The second H-bridge circuit 23 has a first end and a second end. The first end of the second H-bridge circuit 23 is connected to the first end of the secondary side of the transformer 21, and the second end of the second H-bridge circuit 23 is connected to the second end of the secondary side of the transformer 21. The second H-bridge circuit 23 is also connected to the clamping circuit 30. The second H-bridge circuit 23 is used to synchronously rectify and clamp the voltage output by the transformer 21.

[0076] In this embodiment, the first H-bridge circuit 22 adopts a hard-switching full-bridge circuit. The hard-switching full-bridge circuit has a variety of selectable topological structures, can adapt to a wide range of input and load changes, and is easy to understand and design.

[0077] In one embodiment, the first H-bridge circuit 22 includes a first switch tube Q1 , a second switch tube Q2 , a third switch tube Q3 and a fourth switch tube Q4 .

[0078] The input end of the first switch tube Q1 is connected to the output end of the second switch tube Q2, forming a first end of the first H-bridge circuit 22. The output end of the first switch tube Q1 is connected to the positive pole of the power input interface and the output end of the third switch tube Q3. The input end of the second switch tube Q2 is connected to the negative pole of the power input interface and the input end of the fourth switch tube Q4.

[0079] An input end of the third switch tube Q3 is connected to an output end of the fourth switch tube Q4 to form a second end of the first H-bridge circuit 22 .

[0080] In the above embodiment, the first switch tube Q1 , the second switch tube Q2 , the third switch tube Q3 and the fourth switch tube Q4 may be PMOS tubes.

[0081] In this embodiment, the power supply voltage connected to the first H-bridge circuit 22 is controlled by controlling the first switch tube Q1 , the second switch tube Q2 , the third switch tube Q3 and the fourth switch tube Q4 , and the response speed is fast.

[0082] In one embodiment, the second H-bridge circuit 23 includes a fifth switch tube Q5 , a sixth switch tube Q6 , a seventh switch tube Q7 and an eighth switch tube Q8 .

[0083] The input end of the fifth switch tube Q5 is connected to the output end of the sixth switch tube Q6, forming a first end of the second H-bridge circuit 23. The output end of the fifth switch tube Q5 is connected to the output end of the seventh switch tube Q7 and the clamping circuit 30. The input end of the sixth switch tube Q6 is connected to the input end of the eighth switch tube Q8 and the clamping circuit 30.

[0084] An input end of the seventh switch tube Q7 is connected to an output end of the eighth switch tube Q8 to form a second end of the second H-bridge circuit 23 .

[0085] The fifth switch tube Q5 and the seventh switch tube Q7 are used to clamp the voltage output by the transformer 21 , and the sixth switch tube Q6 and the eighth switch tube Q8 are used to synchronously rectify the voltage output by the transformer 21 .

[0086] In the above embodiment, the fifth switch tube Q5, the sixth switch tube Q6, the seventh switch tube Q7 and the eighth switch tube Q8 can be PMOS tubes. Among them, the sixth switch tube Q6 and the eighth switch tube Q8 are used to synchronously rectify the voltage output by the transformer 21. The fifth switch tube Q5 and the seventh switch tube Q7 are used to clamp the voltage output by the transformer 21. When the sixth switch tube Q6 and the eighth switch tube Q8 are disconnected, a large voltage spike signal will be generated. Therefore, the voltage is clamped by the fifth switch tube Q5 and the seventh switch tube Q7 before the sixth switch tube Q6 and the eighth switch tube Q8 are disconnected.

[0087] In this embodiment, the fifth switch tube Q5 and the seventh switch tube Q7 clamp the voltage output by the transformer 21 to prevent voltage spike signals from damaging the circuit. The sixth switch tube Q6 and the eighth switch tube Q8 synchronously rectify the voltage output by the transformer 21 to reduce circuit rectification losses.

[0088] In one embodiment, the DC conversion circuit further includes a main controller.

[0089] The first to eighth switch tubes all have a controlled end, and the main controller is connected to the controlled ends of the first to eighth switch tubes, respectively. The main controller is used to output control signals to the controlled ends of the first to eighth switch tubes, and control the corresponding switch tubes to be turned on or off to access the power supply voltage. The main controller is also used to output control signals to the controlled ends of the fifth switch tube Q5 and the seventh switch tube Q7, and control the corresponding switch tubes to be turned on or off, so as to clamp the voltage output by the transformer 21. The main controller is also used to output control signals to the controlled ends of the sixth switch tube Q6 and the eighth switch tube Q8, and control the sixth switch tube Q6 to be turned on and the eighth switch tube Q8 to be turned off, or control the sixth switch tube Q6 to be turned off and the eighth switch tube Q8 to be turned on, so as to synchronously rectify the voltage output by the transformer 21.

[0090] In one embodiment, the clamping circuit 30 includes a second capacitor C2 .

[0091] The first end of the second capacitor C2 is connected to the output end of the fifth switch tube Q5 and the input end of the safety switch circuit 40, and the second end of the second capacitor C2 is grounded. The second capacitor C2 is used to absorb the voltage spike signal generated when the second H-bridge circuit 23 is working and store energy, and supply power to the safety switch circuit 40.

[0092] In this embodiment, the second capacitor C2 absorbs the voltage spike signal generated when the second H-bridge circuit 23 works and stores energy to supply power to the driving circuit 41, thereby improving energy utilization efficiency and reducing energy waste.

[0093] In one embodiment, the DC conversion circuit further includes a step-down voltage stabilization circuit 70 .

[0094] The step-down and voltage-stabilizing circuit 70 is connected to the output end of the clamp circuit 30 . The step-down and voltage-stabilizing circuit 70 is used to step down and stabilize the voltage output by the clamp circuit 30 and then output it to the safety switch circuit 42 .

[0095] In this embodiment, the voltage-step-down and voltage-stabilizing circuit 70 steps down and stabilizes the energy storage voltage output from the clamping circuit 30 to the driving circuit 41 , so that the driving circuit 41 works more stably.

[0096] In one embodiment, the buck stabilizing circuit 70 includes a first resistor R1 and a zener diode D1 .

[0097] An input end of the first resistor R1 is connected to the clamp circuit 30 , an output end of the first resistor R1 is connected to the drive circuit 41 , and the Zener diode D1 is connected in parallel to the drive circuit 41 .

[0098] The principle of the present invention will be specifically described below in conjunction with the accompanying drawings:

[0099] Since there is no inductance in the hard-switching full-bridge circuit, the current changes very quickly, and a large voltage spike signal will appear on the secondary side of the transformer 21. Therefore, a second capacitor C2 is added to the second H-bridge circuit 23 to absorb the voltage spike signal and store energy. The operation of the drive circuit 41 in the safety switch circuit 40 requires power supply. The additional addition of an auxiliary source circuit to supply power to the drive circuit 41 increases the complexity of the circuit design and also increases the cost. Therefore, the energy stored in the second capacitor C2 is used to supply power to the drive circuit 41, which saves the design of the auxiliary source circuit, reduces the circuit size and cost, and does not waste the energy stored in the second capacitor C2.

[0100] The present invention absorbs the voltage peak signal through the second capacitor, stores energy, and supplies power to the driving circuit, thereby making the circuit structure simpler, reducing costs, and improving energy utilization efficiency.

[0101] The above are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A DC conversion circuit, characterized in that: The DC conversion circuit comprises: A power input terminal, the power input terminal is used to connect to a power source; An output interface, the output interface being used to connect to a battery; A DC-DC converter, wherein an input terminal of the DC-DC converter is connected to the power input terminal; The DC-DC converter is used to convert the connected power supply voltage and then output it; A safety switch circuit, wherein a first input end of the safety switch circuit is connected to an output end of the DC-DC converter, and an output end of the safety switch circuit is connected to the output interface; The safety switch circuit is used to be turned on when the battery is normally connected to the output interface, output the voltage output by the DC-DC converter to the output interface, and to be turned off when the positive and negative poles of the battery and the output interface are reversely connected; A clamping circuit, wherein an input end of the clamping circuit is connected to the DC-DC converter, and an output end of the clamping circuit is connected to a second input end of the safety switch circuit; The clamping circuit is used to absorb the voltage spike signal generated when the DC-DC converter is working and store energy, and to supply power to the safety switch circuit. The safety switch circuit receives the energy storage voltage of the clamping circuit to work; The primary side of the DC-DC converter is a hard-switching full-bridge circuit; The safety switch circuit comprises a drive circuit and a safety switch; The input end of the driving circuit is connected to the output end of the clamping circuit, the driving circuit receives the energy storage voltage of the clamping circuit to work, and the output end of the driving circuit is connected to the controlled end of the safety switch; The input end of the safety switch is connected to the output end of the DC-DC converter, and the output end of the safety switch is connected to the output interface. The safety switch is used to be turned on under the control of the drive circuit to output the voltage output by the DC-DC converter to the output interface. The safety switch is also used to be disconnected when the positive and negative poles of the battery and the output interface are reversely connected.

2. The DC conversion circuit according to claim 1, characterized in that: The DC conversion circuit also includes a filter circuit; The input end of the filter circuit is connected to the output end of the DC-DC converter, the output end of the filter circuit is connected to the safety switch tube circuit, and the filter circuit is used to filter the voltage output by the DC-DC converter.

3. The DC conversion circuit according to claim 2, characterized in that: The filter circuit includes a first inductor and a first capacitor; The input end of the first inductor is connected to the output end of the DC-DC converter, the output end of the first inductor is connected to the input end of the safety switch, the first end of the first capacitor is connected to the DC-DC converter, and the second end of the first capacitor is connected to both the output end of the first inductor and the input end of the safety switch.

4. The DC conversion circuit according to claim 1, characterized in that: The DC-DC converter includes a transformer, a first H-bridge circuit and a second H-bridge circuit; The primary side of the transformer has a first end and a second end, the secondary side of the transformer has a first end, a second end and a third end, the third end of the secondary side of the transformer is located between the first end and the second end of the secondary side of the transformer, and the third end of the secondary side of the transformer is connected to the input end of the safety switch circuit; The first H-bridge circuit has a first end and a second end, the first end of the first H-bridge circuit is connected to the first end of the primary side of the transformer, and the second end of the first H-bridge circuit is connected to the second end of the primary side of the transformer; the first H-bridge circuit is used to output the input power supply voltage to the transformer for voltage conversion; The second H-bridge circuit has a first end and a second end, the first end of the second H-bridge circuit is connected to the first end of the secondary side of the transformer, and the second end of the second H-bridge circuit is connected to the second end of the secondary side of the transformer; the second H-bridge circuit is also connected to the clamping circuit; the second H-bridge circuit is used to synchronously rectify and clamp the voltage output by the transformer.

5. The DC conversion circuit according to claim 4, characterized in that: The first H-bridge circuit includes a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; The input end of the first switch tube is connected to the output end of the second switch tube to form a first end of the first H-bridge circuit, the output end of the first switch tube is connected to the positive electrode of the power input interface and the output end of the third switch tube, and the input end of the second switch tube is connected to the negative electrode of the power input interface and the input end of the fourth switch tube; The input end of the third switch tube is connected to the output end of the fourth switch tube to form the second end of the first H-bridge circuit.

6. The DC conversion circuit according to claim 4, characterized in that: The second H-bridge circuit includes a fifth switch tube, a sixth switch tube, a seventh switch tube and an eighth switch tube; The input end of the fifth switch tube is connected to the output end of the sixth switch tube to form the first end of the second H-bridge circuit, the output end of the fifth switch tube is connected to the output end of the seventh switch tube and the clamping circuit, and the input end of the sixth switch tube is connected to the input end of the eighth switch tube and the clamping circuit; The input end of the seventh switch tube is connected to the output end of the eighth switch tube to form the second end of the second H-bridge circuit; The fifth switch tube and the seventh switch tube are used to clamp the voltage output by the transformer, and the sixth switch tube and the eighth switch tube are used to synchronously rectify the voltage output by the transformer.

7. The DC conversion circuit according to claim 6, characterized in that: The clamping circuit includes a second capacitor; The first end of the second capacitor is connected to the output end of the fifth switch tube and the input end of the safety switch circuit, and the second end of the second capacitor is grounded. The second capacitor is used to absorb the voltage spike signal generated when the second H-bridge circuit is working and store energy, and supply power to the safety switch circuit.

8. The DC conversion circuit according to claim 1, characterized in that: The DC conversion circuit also includes a step-down voltage stabilization circuit; The step-down and voltage-stabilizing circuit is connected to the output end of the clamping circuit, and is used for stepping down and stabilizing the voltage output by the clamping circuit and then outputting it to the safety switch circuit.

9. The DC conversion circuit according to claim 8, characterized in that: The step-down voltage stabilization circuit comprises a first resistor and a voltage stabilization diode; The input end of the first resistor is connected to the clamping circuit, the output end of the first resistor is connected to the driving circuit, and the voltage regulator diode is connected in parallel to the driving circuit.

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