Overcurrent protection device and converter

Abstract

The utility model provides an overcurrent protection device and a converter, the overcurrent protection device comprises a magnetic sensor, a peak current comparison circuit and an auxiliary magnetic circuit arranged on a power inductor, the magnetic sensor is fixed on the auxiliary magnetic circuit, and the magnetic sensor is electrically connected with the peak current comparison circuit; the magnetic sensor is used for acquiring the flux density value of the auxiliary magnetic circuit in the working process of the power inductor; the peak current comparison circuit is used for determining the peak current of the power inductor according to the flux density value, and outputting an alarm signal when the peak current is greater than or equal to a preset current threshold. Through the implementation of the scheme, the auxiliary magnetic circuit is arranged on the power inductor to obtain the flux density value of the power inductor, and then the corresponding current value is calculated according to the flux density value, so that overcurrent protection of the converter access is realized, and the safety guarantee of the converter is improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to circuit electron technology field especially, it relates to a kind of overcurrent protection device and converter. BACKGROUND

[0002] In many application occasions of converter, energy buffer device such as power inductance needs to be used to realize the conversion of electric energy.Power inductance can be usually connected in series between bridge arm, and closely cooperate with the switching action of switch tube, and generally pass larger current;And realize electric energy conversion under smaller volume, power inductance is generally operated under higher frequency (several kHz to several hundred kHz).

[0003] When the converter is short-circuited due to abnormal output loading, output short circuit, wave emission abnormality, device damage and other factors, it will cause the current in the converter to be too large.The excessively large current will cause the device to overheat, affect the service life of the device, and even burn out the device;Extremely large instantaneous current can even produce extremely large local temperature rise, directly burning out the device.Therefore, an overcurrent protection component is generally provided in the converter.

[0004] In related technologies, the overcurrent protection measure of the converter is generally to set the overcurrent protection component at the input and / or output end of the converter (such as setting a fuse), to directly disconnect the connection between the converter and the power supply, load when the current is too large.However, the overcurrent generated in the converter path cannot be protected by this method, and the overcurrent generated in the converter path will cause the overcurrent protection measure at the output end to be ineffective. INVENTION CONTENTS

[0005] The technical purpose of the utility model is to provide an overcurrent protection device and a converter, to solve the problem that it is difficult to implement overcurrent protection for the path of the converter in related technologies.

[0006] To solve the above technical problems, the utility model is implemented as follows: on the one hand, an overcurrent protection device is provided, which is applied to overcurrent detection of power inductance in a converter, and the overcurrent protection device comprises a magnetic sensor, a peak current comparison circuit and an auxiliary magnetic circuit arranged on the power inductance, the magnetic sensor is fixed on the auxiliary magnetic circuit, and the magnetic sensor is electrically connected to the peak current comparison circuit;The magnetic sensor is used to obtain the magnetic flux density value of the auxiliary magnetic circuit during the operation of the power inductance;The peak current comparison circuit is used to determine the peak current of the power inductance according to the magnetic flux density value, and output an alarm signal when the peak current is greater than or equal to a preset current threshold.

[0007] Preferably, the auxiliary magnetic circuit is formed on the surface of the power inductance.

[0008] Preferably, the magnetic core of the power inductance comprises a plurality of magnets, and the auxiliary magnetic circuit is arranged at the spliced interface of the adjacent two magnets.

[0009] Preferably, the two magnets are provided with grooves respectively at the end faces near the split joint, and the two grooves jointly enclose an auxiliary magnetic circuit.

[0010] Preferably, the grooves are engraved and formed structures.

[0011] Preferably, the magnet and the corresponding groove are integrally formed structures.

[0012] Preferably, the two magnets are respectively connected with protrusions at the end faces, and the two protrusions and the end faces of the two magnets jointly enclose an auxiliary magnetic circuit.

[0013] Preferably, the magnet and the corresponding protrusion are connected through a first adhesive part.

[0014] Preferably, the magnet and the corresponding protrusion are integrally formed structures.

[0015] Preferably, when the magnet and the corresponding protrusion are connected through the first adhesive part, the magnetic sensor, the peak current comparison circuit, and the protrusion are a packaging module.

[0016] Or, when the magnet and the corresponding protrusion are integrally formed structures, the magnetic sensor and the peak current comparison circuit are a packaging module, and the packaging module is connected with the transformer through a second adhesive part.

[0017] Preferably, the peak current comparison circuit includes a peak detection circuit and a comparison circuit, the peak detection circuit is connected between the magnetic sensor and the comparison circuit, the peak detection circuit is used for determining the peak current of the power inductor according to the magnetic flux density value and sending the peak current to the comparison circuit, and the comparison circuit is used for outputting an alarm signal when the peak current is greater than or equal to a preset current threshold.

[0018] In another aspect, a transformer is provided, including a power inductor, a switch tube, a transformer, and an overcurrent protection device according to the first aspect, wherein the power inductor is connected between the switch tube and the transformer, and the overcurrent protection device is used for overcurrent protection of a path where the switch tube, the power inductor, and the transformer are located.

[0019] Compared with the prior art, the overcurrent protection device and the transformer in the utility model have the beneficial effects that: an auxiliary magnetic circuit is arranged on the power inductor, the current value of the transformer path is indirectly obtained by collecting the magnetic flux density value of the auxiliary magnetic circuit, overcurrent judgment is completed, and overcurrent protection is realized. That is, through the implementation of the application scheme, overcurrent detection of the transformer path can be realized, an alarm signal is generated in time when overcurrent of the path is detected, protection measures are taken by the rear circuit, and the safety guarantee of the transformer is improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1It is the overall structure schematic diagram of the overcurrent protection device in the embodiment of the utility model;

[0021] Figure 2 It is the working principle schematic diagram of the auxiliary magnetic circuit in the power inductance in the embodiment of the utility model;

[0022] Figure 3 It is the partial structure schematic diagram of the power inductance in the first kind of implementation of the utility model;

[0023] Figure 4 It is the partial structure schematic diagram of the power inductance in the second kind of implementation of the utility model;

[0024] Figure 5 It is the partial structure schematic diagram of the power inductance in the third kind of implementation of the utility model;

[0025] Figure 6 It is the partial structure schematic diagram of the power inductance in the fourth kind of implementation of the utility model.

[0026] In the drawings, various reference signs represent: 1, power inductance;11, magnetic core;12, auxiliary magnetic circuit;12a, recess;12b, protrusion;2, magnetic sensor;3, peak current comparison circuit;31, peak detection circuit;32, comparison circuit;4, switch tube. DETAILED DESCRIPTION

[0027] The embodiments of the utility model are described in detail below, the examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the utility model, and cannot be understood as a limitation of the utility model. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the utility model.

[0028] In the description of the utility model, it is understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "circumferential", "radial" is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the utility model.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] In related technologies, the traditional overcurrent protection for inductor current involves detecting the high-frequency current of the power inductor and then performing peak detection on the detected high-frequency current signal. When the peak value reaches a preset threshold, the converter stops operating. However, detecting the high-frequency current in the power inductor typically requires a combination of a shunt and an isolation operational amplifier, or various current sensors. The shunt and isolation operational amplifier combination requires additional components connected in series in the circuit. These components have significant losses under high current conditions, and are also bulky and expensive. Current sensors are also expensive.

[0031] To address the aforementioned deficiencies in related technologies, embodiments of this application provide an overcurrent protection device and a converter.

[0032] Example:

[0033] like Figures 1-6 As shown, in this embodiment, the converter includes a power inductor 1, an overcurrent protection device for the power inductor 1, a switching transistor 4, and a transformer. The power inductor 1 is connected between the switching transistor 4 and the transformer. The overcurrent protection device is used to provide overcurrent protection for the circuit containing the switching transistor 4, the power inductor 1, and the transformer.

[0034] The converter in this embodiment can be a DC-DC converter. Multiple switching transistors 4 can be incorporated into the converter to form a bridge arm circuit. Furthermore, in some specific implementations, inductors, filter capacitors, etc., can be connected to the input and output terminals of the converter respectively to filter out ripple and provide smooth input and output voltages; this is not a limitation.

[0035] like Figures 1-6 As shown, in this embodiment, the overcurrent protection device is used for overcurrent detection of the power inductor 1 in the converter. The overcurrent protection device includes: a magnetic sensor 2, a peak current comparison circuit 3, and an auxiliary magnetic circuit 12 disposed on the power inductor 1. The size of the power inductor 1 is larger than the size of the auxiliary magnetic circuit 12. The magnetic sensor 2 is fixed on the auxiliary magnetic circuit 12 and electrically connected to the peak current comparison circuit 3. The magnetic sensor 2 is used to obtain the magnetic flux density value of the auxiliary magnetic circuit 12 during the operation of the power inductor 1. The peak current comparison circuit 3 is used to determine the peak current of the power inductor 1 based on the magnetic flux density value and output an alarm signal when the peak current is greater than or equal to a preset current threshold.

[0036] Specifically, the overcurrent protection measure is applied in the passage of the bridge arm-power inductor-transformer; the auxiliary magnetic circuit 12 is arranged on the power inductor 1, the magnetic density value of the auxiliary magnetic circuit 12 is collected to indirectly obtain the passage current value, and then the overcurrent judgment is completed to realize the overcurrent protection. The arrangement of the auxiliary magnetic circuit 12 also solves the insulation problem of sampling. Without the combination structure of the shunt and the isolation operational amplifier, the loss is reduced, the production cost is reduced, and the installation space is reduced. Without the arrangement of the current sensor, the cost is saved.

[0037] In the embodiment, as shown in Figure 1 , the peak current comparison circuit 3 includes a peak detection circuit 31 and a comparison circuit 32, the peak detection circuit 31 is connected between the magnetic sensor 2 and the comparison circuit 32, the peak detection circuit 31 is used to determine the peak current of the power inductor 1 according to the magnetic density value and send the peak current to the comparison circuit 32, and the comparison circuit 32 is used to output an alarm signal when the peak current is greater than or equal to a preset current threshold.

[0038] Specifically, in the embodiment, the magnetic field (magnetic density) in the power inductor 1 has a direct proportional relationship with the current flowing therethrough, and the corresponding current value can be represented by detecting the magnetic field (magnetic density) of the magnetic core 11 in the power inductor 1. That is, the peak detection circuit 31 can calculate the magnetic density value of the power inductor 1 according to the magnetic density value of the auxiliary magnetic circuit 12 measured by the magnetic sensor 2, and then calculate the peak current of the power inductor 1 according to the magnetic density value of the power inductor 1. Then, the comparison circuit 32 can compare the detected peak current with the preset current threshold, and when the comparison result is that the peak current is greater than or equal to the preset current threshold, an alarm signal is output for the protection measure of the subsequent circuit. As shown in Figure 1 , in some specific embodiments, the comparison circuit 32 can include a first branch in which a comparator corresponding to a first preset current value (maximum value I max ) is located, a second branch in which a comparator corresponding to a second preset current value (minimum value I min ) is located, and an alarm signal output unit, the first branch and the second branch are respectively connected to the alarm signal output unit; the alarm signal output unit can be an OR gate structure, which is used to output an alarm signal when the peak current is greater than or equal to I max , or, the peak current is less than or equal to I min .

[0039] As shown in Figure 2 , the working principle diagram of the auxiliary magnetic circuit 12, in the power inductor 1, the magnetic core 11 structure itself forms a main magnetic circuit, , which represents the magnetic circuit reluctance of the overlapping part of the main magnetic circuit and the auxiliary magnetic circuit 12; represents the magnetic reluctance corresponding to the auxiliary magnetic circuit 12, most of which is generated by the air gap formed by the auxiliary magnetic circuit 12; represents the magnetic reluctance corresponding to the auxiliary magnetic circuit 12, most of which is generated by the air gap formed by the auxiliary magnetic circuit 12; represents the magnetic reluctance corresponding to the auxiliary magnetic circuit 12, most of which is generated by the air gap formed by the auxiliary magnetic circuit 12; Thus, the magnetic core magnetic flux is mainly collected in the main magnetic flux Therefore, the auxiliary magnetic circuit 12 has little effect on the main magnetic circuit. Further, the relationship between the auxiliary magnetic flux and the magnetic core magnetic flux can be expressed as:

[0040]

[0041] The relationship between the magnetic flux density value of the auxiliary magnetic circuit 12 and the magnetic flux density value of the magnetic core 11 can be expressed as:

[0042]

[0043] wherein, The coefficient c can be obtained by experimental testing, which is affected by the cross-sectional area of the auxiliary magnetic circuit 12 and the length of the air gap. According to the magnetic flux density value measured by the magnetic sensor, and the coefficient c, the magnetic flux density value of the magnetic core 11 of the power inductor 1 can be calculated. It should be understood that in the specific implementation process, the size of the auxiliary magnetic circuit 12 can be determined according to the size of the magnetic sensor (the smaller the size, the better), which is not limited here.

[0044] In the embodiment, the auxiliary magnetic circuit 12 is formed on the surface of the power inductor 1. Specifically, the auxiliary magnetic circuit 12 can be arranged on the surface of a single magnetic core 11, or formed between multiple magnetic cores 11, which is not limited here. For example, in a specific embodiment, when the auxiliary magnetic circuit is formed on the surface of a single magnetic core, the auxiliary magnetic circuit can be a groove arranged on the surface of the magnetic core. In another specific embodiment, when the auxiliary magnetic circuit is formed on the surface of a single magnetic core, two protrusions can be arranged on the surface of the magnetic core, and the two protrusions and the magnetic surface jointly enclose the auxiliary magnetic circuit.

[0045] Preferably, in the embodiment, the magnetic core 11 of the power inductor 1 comprises a plurality of magnets, and the auxiliary magnetic circuit 12 is arranged at the joint between two adjacent magnets; that is, the magnetic core 11 is composed of a plurality of magnets, and the auxiliary magnetic circuit 12 is in communication with the gap formed at the joint between the two magnets. In a specific embodiment, the magnetic core 11 can comprise two magnets, which can be symmetrically arranged or asymmetrically arranged, and the shapes of the two magnets can be the same or different, which is not limited herein; the auxiliary magnetic circuit 12 is arranged at the joint between the two magnets, and the gap between the two magnets is in communication with the auxiliary magnetic circuit 12. The existence of the gap can adjust the distribution of the magnetic flux, avoid magnetic saturation, and reduce the loss at the same time.

[0046] In the embodiment, as shown in Figure 3 and 4 , the end faces of the two magnets near the joint are respectively provided with grooves 12a; that is, the end faces of the two magnets facing the gap are respectively provided with grooves 12a, and the two grooves 12a jointly form the auxiliary magnetic circuit 12; this facilitates the reduction of the size of the device, and the magnetic sensor 2 is fixed at any position on the auxiliary magnetic circuit 12, so as to detect the magnetic flux density value of the auxiliary magnetic circuit 12. As shown in Figure 3 , in a first specific embodiment, the groove 12a is a carved structure; that is, the groove 12a structure can be carved on the surface of the magnet by a carving machine. Since the power inductor 1 itself has a large size, the setting of the groove 12a will not have too much impact on the main body of the magnet, the manufacturing cost is low, and it is easy to implement. As shown in Figure 4 , in a second specific embodiment, the magnet and the corresponding groove 12a are an integral molded structure; that is, after the shape and size of the groove 12a are determined, a corresponding mold is designed, so that the magnet with the groove 12a can be directly obtained in the mold opening process, and the production cost is low.

[0047] In the embodiment, as shown in Figure 5 and 6 , the end faces of the two magnets are respectively connected with protrusions 12b, and the two protrusions 12b and the end faces of the two magnets jointly form the auxiliary magnetic circuit 12; that is, the protrusion 12b and the outer surface of the magnet jointly form an air gap, and the magnetic sensor 2 is fixed in the air gap, so as to detect the magnetic flux density value of the auxiliary magnetic circuit 12. The setting of the protrusion 12b will not damage the original form of the magnet (main magnetic circuit), and can play a role in ensuring the stable performance of the power inductor 1. As shown in Figure 5As shown in the third specific embodiment, two protrusions 12b (two additional magnet structures) are arranged at intervals, and the two protrusions 12b and the outer surfaces of the two magnets jointly enclose the auxiliary magnetic circuit 12; the magnets and the protrusions 12b are connected through the first adhesive part, that is, the magnets and the protrusions 12b can be fixed through the adhesive mode, which is simple and convenient to operate, and the size of the protrusions 12b can be controlled to be smaller. Figure 6 As shown in the fourth specific embodiment, two protrusions 12b (the protrusions 12b can be additional magnet structures) are arranged at intervals, and the two protrusions 12b and the outer surfaces of the magnets jointly enclose the auxiliary magnetic circuit 12; the magnets and the protrusions 12b are integrally formed structures, and the production cost is low. It can be understood that in the specific implementation process, the method for constructing the auxiliary magnetic circuit 12 can be selected according to the actual equipment conditions, economic conditions, size requirements of the power inductor 1 in the transformer, connection requirements between the power inductor 1 and related devices and other factors, which is not limited here.

[0048] Further, in one implementation mode of the embodiment, when the magnets and the corresponding protrusions 12b are connected through the first adhesive part, the magnetic sensor 2, the peak current comparison circuit 323 and the protrusions 12b are a packaging module, and in actual use, the protrusions 12b of the packaging module can be connected with the magnets of the transformer through the first adhesive part. In another implementation mode of the embodiment, when the magnets and the corresponding protrusions 12b are integrally formed structures, the magnetic sensor 2 and the peak current comparison circuit 323 are a packaging module, and the packaging module is connected with the transformer through the second adhesive part. Specifically, the magnetic sensor 2, the peak detection circuit 31 and the comparison circuit 32 and other structures can be packaged into a separate module, and the connection stability between the auxiliary magnetic circuit 12 of the power inductor 1 and the magnetic sensor 2 can be ensured through the second adhesive part. Of course, the second adhesive part can also be used to strengthen the connection stability of other connection parts between the packaging module and the transformer; when over-current protection detection is required, the entire packaging module can be directly pasted to the corresponding position of the transformer through the second adhesive part, which is convenient for direct installation and use.

[0049] The above is only a preferred embodiment of the utility model, and does not limit the utility model, and any modification, equivalent replacement and improvement within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. An overcurrent protection device, characterized by The application discloses an overcurrent detection device for a power inductor in a transformer, and belongs to the technical field of overcurrent protection. The overcurrent protection device comprises a magnetic sensor, a peak current comparison circuit and an auxiliary magnetic circuit arranged on the power inductor. The magnetic sensor is fixed on the auxiliary magnetic circuit and electrically connected to the peak current comparison circuit.

2. The overcurrent protection device of claim 1, wherein The peak current comparison circuit is used for determining the peak current of the power inductor according to the magnetic flux density value and outputting an alarm signal when the peak current is greater than or equal to a preset current threshold.

3. The overcurrent protection device of claim 2, wherein, The auxiliary magnetic circuit is formed on the surface of the power inductor.

4. The overcurrent protection device of claim 3, wherein The magnetic core of the power inductor comprises a plurality of magnets, and the auxiliary magnetic circuit is arranged at the joint of two adjacent magnets.

5. The overcurrent protection device of claim 4, wherein, The end surface of each of the two magnets near the joint is provided with a groove, and the two grooves jointly form the auxiliary magnetic circuit.

6. The overcurrent protection device of claim 3, wherein The groove is a carved structure, or the magnet and the corresponding groove are an integral structure.

7. The overcurrent protection device of claim 6, wherein The end surface of each of the two magnets is connected with a protrusion, and the two protrusions and the end surfaces of the two magnets jointly form the auxiliary magnetic circuit.

8. The overcurrent protection device of claim 7, wherein, The magnet and the corresponding protrusion are connected through a first adhesive part, or the magnet and the corresponding protrusion are an integral structure. When the magnet and the corresponding protrusion are connected through the first adhesive part, the magnetic sensor, the peak current comparison circuit and the protrusion form a packaging module.

9. The overcurrent protection device of claim 1, wherein, When the magnet and the corresponding protrusion are an integral structure, the magnetic sensor and the peak current comparison circuit form a packaging module, and the packaging module is connected with the transformer through a second adhesive part.

10. A converter, characterized by The peak current comparison circuit comprises a peak detection circuit and a comparison circuit, and the peak detection circuit is connected between the magnetic sensor and the comparison circuit. The peak detection circuit is used for determining the peak current of the power inductor according to the magnetic flux density value and sending the peak current to the comparison circuit. The comparison circuit is used for outputting the alarm signal when the peak current is greater than or equal to the preset current threshold. The application further discloses a transformer comprising a power inductor, a switch tube, a transformer and the overcurrent protection device.

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