Detection circuit, protection circuit, switching circuit and power supply circuit

Abstract

The invention provides a detection circuit, a protection circuit, a switching circuit and a power supply circuit, the detection circuit is used for the switching circuit, and the switching circuit comprises a first switching sub-circuit and a second switching sub-circuit which are connected in parallel. The detection circuit comprises a first inductor, a second inductor and a third inductor. The first inductor is connected with the first switch sub-circuit and used for generating a first magnetic field based on first current of the first switch sub-circuit; the second inductor is connected with the second switch sub-circuit and is used for generating a second magnetic field based on second current of the second switch sub-circuit; the third inductor generates detection voltage based on a combined magnetic field of the first magnetic field and the second magnetic field; wherein the first magnetic field and the second magnetic field are opposite to each other. Through the mode, the circuit structure of the detection circuit can be effectively simplified, and the cost of the detection circuit is reduced.

Description

Technical Field

[0001] This application relates to the technical field of protection circuits, and particularly to a detection circuit, a protection circuit, a switching circuit, and a power supply circuit. Background Art

[0002] With the development of SiC devices, switching transistors, such as SiC switching transistors, etc., are used more and more frequently in high-frequency power supply circuits. However, with the continuous increase of power supply power, in order to improve the efficiency of the system, multiple SiC switching transistors are used in parallel, for example, two SiC switching transistors are connected in parallel to reduce conduction loss and thus improve the efficiency of the system. However, during the parallel use of multiple SiC switching transistors, the phenomenon of current imbalance usually occurs. For example, the current flowing through one SiC switching transistor is not equal to the current flowing through another SiC switching transistor. Once the current imbalance exceeds a certain range, it will accelerate the aging speed of SiC switching transistors, and then cause destructive consequences, such as the transistor exploding and posing a threat to personal safety. In the prior art, usually a corresponding current detection circuit is set in each SiC switching transistor to detect the current flowing through each SiC switching transistor one by one, and then the measured currents of each path are compared to determine whether the current of each path is unbalanced. This method has a too complex circuit structure and a high cost. Summary of the Invention

[0003] This application provides a detection circuit, a protection circuit, a switching circuit, and a power supply circuit, which are used to simplify the circuit structure of the detection circuit and reduce the cost of the detection circuit.

[0004] To solve the above technical problems, the technical solution adopted in this application is: to provide a detection circuit for a switching circuit. The switching circuit includes a first switching sub-circuit and a second switching sub-circuit connected in parallel. The detection circuit includes: a first inductor connected to the first switching sub-circuit, which is used to generate a first magnetic field based on a first current of the first switching sub-circuit; a second inductor connected to the second switching sub-circuit, which is used to generate a second magnetic field based on a second current of the second switching sub-circuit; a third inductor, and the third inductor generates a detection voltage based on a combined magnetic field of the first magnetic field and the second magnetic field; wherein, the first magnetic field and the second magnetic field are opposite to each other.

[0005] In some embodiments, the detection circuit includes: a voltage stabilizing circuit connected to the third inductor.

[0006] In some embodiments, the voltage stabilizing circuit includes: a first resistor, whose first signal terminal is connected to the first signal terminal of the third inductor, and whose second signal terminal is connected to the second signal terminal of the third inductor; a first diode, whose first signal terminal is connected to the first signal terminal of the first resistor; a second diode, whose first signal terminal is connected to the first signal terminal of the first diode, and whose second signal terminal is grounded; a third diode, whose first signal terminal is connected to the second signal terminal of the first resistor, and whose second signal terminal is connected to the second signal terminal of the first diode; a fourth diode, whose first signal terminal is connected to the first signal terminal of the third diode, and whose second signal terminal is grounded.

[0007] In some embodiments, the detection circuit includes: a filtering circuit, connected to the voltage stabilizing circuit, for filtering the filtered circuit after voltage stabilization processing by the voltage stabilizing circuit.

[0008] In some embodiments, the filtering circuit includes: a second resistor, whose first signal terminal is connected to the voltage stabilizing circuit; the second signal terminal of the second resistor is grounded; a first capacitor, whose first signal terminal is connected to the voltage stabilizing circuit; the second signal terminal of the first capacitor is grounded.

[0009] To solve the above technical problems, the technical solution adopted by this application is: to provide a protection circuit, the protection circuit includes the detection circuit in any of the above embodiments, and the protection circuit further includes: a control circuit, which accesses the detection voltage, and based on the detection voltage and the reference voltage, when the difference between the first current of the first switching sub - circuit and the second current of the second switching sub - circuit is greater than a preset threshold, reduces the total power of the switching circuit.

[0010] In some embodiments, the preset threshold is greater than or equal to 0 and less than or equal to a first upper limit value.

[0011] To solve the above technical problems, the technical solution adopted by this application is: to provide a switching circuit, the switching circuit includes the protection circuit in any of the above embodiments, and the switching circuit further includes a first switching sub - circuit and a second switching sub - circuit connected in parallel with each other.

[0012] In some embodiments, the first switching sub - circuit includes a SiC switching tube; and / or the second switching sub - circuit includes a SiC switching tube.

[0013] To solve the above technical problems, the technical solution adopted by this application is: to provide a power supply circuit, the power supply circuit includes the switching circuit in any of the above embodiments, and the power supply circuit further includes a power supply, which is connected to the switching circuit.

[0014] The beneficial effects of the embodiments of the present application are as follows: The detection circuit of the present application includes a first inductor, a second inductor, and a third inductor. Among them, the first inductor is used to generate a first magnetic field based on a first current, the second inductor is used to generate a second magnetic field based on a second current, and the third inductor generates a detection voltage that can reflect the magnitude relationship between the first current and the second current based on the combined magnetic field of the first magnetic field and the second magnetic field. Based on this, the detection circuit can generate a detection voltage that can reflect the current relationship between the first switching sub-circuit and the second switching sub-circuit through the first inductor, the second inductor, and the third inductor, effectively simplifying the circuit structure of the detection circuit, thereby effectively reducing the cost of the detection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic circuit diagram of an embodiment of the power supply circuit of the present application;

[0016] Figure 2 is Figure 1 a detailed schematic circuit diagram of the detection circuit, the first switching sub-circuit, and the second switching sub-circuit shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0018] The terms "first" and "second" in the present application are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products, or devices.

[0019] The present application provides a detection circuit 100, as Figure 1 and Figure 2 shown, the detection circuit 100 is used for the switching circuit 30. Among them, in other embodiments, the detection circuit 100 can also be applied to other circuits that require detection functions. Here, the present application mainly elaborates on the detection circuit 100 of the present application based on the actual application of the detection circuit 100 in the switching circuit 30.

[0020] Among them, as Figure 1 and Figure 2 shown, the switching circuit 30 includes a first switching sub-circuit K1 and a second switching sub-circuit K2 connected in parallel with each other.

[0021] The detection circuit 100 includes: a first inductor L1, a second inductor L2, and a third inductor L3. The first inductor L1 is connected to the first switching sub-circuit K1 and is used to generate a first magnetic field based on a first current of the first switching sub-circuit K1; the second inductor L2 is connected to the second switching sub-circuit K2 and is used to generate a second magnetic field based on a second current of the second switching sub-circuit K2; the third inductor L3 generates a detection voltage V based on a combined magnetic field of the first magnetic field and the second magnetic field; wherein, the first magnetic field and the second magnetic field are opposite to each other.

[0022] Specifically, in this embodiment, the switching circuit 30 includes a first switching sub-circuit K1 and a second switching sub-circuit K2 connected in parallel with each other. The detection circuit 100 includes a first inductor L1, a second inductor L2, and a third inductor L3. Among them, the first inductor L1 is connected to the first switching sub-circuit K1 and generates a first magnetic field based on the first current, and the second inductor L2 is connected to the second switching sub-circuit K2 and generates a second magnetic field based on the second current. Among them, the first magnetic field and the second magnetic field are opposite to each other. Based on this, the detection voltage V generated by the third inductor L3 based on the combined magnetic field of the first magnetic field and the second magnetic field can effectively reflect the relationship between the first current and the second current. Among them, according to the electromagnetic conversion principle, the magnitude of the detection voltage V depends on the magnitude of the difference between the first current and the second current. In other words, the detection voltage V is proportional to the difference between the first current and the second current. Therefore, the magnitude of the detection voltage V can effectively and accurately reflect the relationship between the first current and the second current.

[0023] For example, the first inductor L1 and the second inductor L2 are inductors with the same number of turns. At the moment when the switching circuit 30 is turned on or off, the first current suddenly generated in the first switching sub-circuit K1 causes the first inductor L1 to generate a first magnetic field corresponding to the first current, and the second current suddenly generated in the second switching sub-circuit K2 causes the second inductor L2 to generate a second magnetic field corresponding to the first current. Among them, if the first magnetic field and the second magnetic field are completely cancelled out, and the detection voltage V generated by the third inductor L3 based on the combined magnetic field is 0, it indicates that there is no current unbalance between the first switching sub-circuit K1 and the second switching sub-circuit K2, that is, the first current and the second current are equal. On the contrary, if the first magnetic field and the second magnetic field are not completely cancelled out, and the detection voltage V generated by the third inductor based on the combined magnetic field is greater than 0, it indicates that there is a current unbalance between the first switching sub-circuit K1 and the second switching sub-circuit K2, that is, the first current and the second current are not equal. Optionally, in other embodiments, the number of turns of the coils of the first inductor L1 and the second inductor L2 may be different, which will not be elaborated in detail here.

[0024] Different from the prior art, the detection circuit 100 of the present application includes a first inductor L1, a second inductor L2 and a third inductor L3. Among them, the first inductor L1 is used to generate a first magnetic field based on the first current, the second inductor L2 is used to generate a second magnetic field based on the second current, and the third inductor L3 generates a detection voltage V that can reflect the magnitude relationship between the first current and the second current based on the combined magnetic field of the first magnetic field and the second magnetic field. Based on this, the detection circuit 100 can generate a detection voltage V that can reflect the current relationship between the first switching sub-circuit K1 and the second switching sub-circuit K2 through the first inductor L1, the second inductor L2 and the third inductor L3, effectively simplifying the circuit structure of the detection circuit 100, thereby effectively reducing the cost of the detection circuit 100.

[0025] Optionally, as Figure 2 shown, the detection circuit 100 includes: a voltage stabilizing circuit 120, connected to the third inductor L3. Specifically, in this embodiment, the detection circuit 100 further includes a voltage stabilizing circuit 120, where the voltage stabilizing circuit 120 is connected to the third inductor L3 and is used to perform voltage stabilization processing on the detection voltage V.

[0026] Specifically, as Figure 2As shown in the figure, the voltage stabilizing circuit 120 includes: a first resistor R1, a first diode D2, a second diode D4, a third diode D1, and a fourth diode D3. Among them, the first signal terminal of the first resistor R1 is connected to the first signal terminal of the third inductor L3, and the second signal terminal of the first resistor R1 is connected to the second signal terminal of the third inductor L3. The first signal terminal of the first diode D2 is connected to the first signal terminal of the first resistor R1. The first signal terminal of the second diode D4 is connected to the first signal terminal of the first diode D2, and the second signal terminal of the second diode D4 is grounded. The first signal terminal of the third diode D1 is connected to the second signal terminal of the first resistor R1, and the second signal terminal of the third diode D1 is connected to the second signal terminal of the first diode D2. The first signal terminal of the fourth diode D3 is connected to the first signal terminal of the third diode D1, and the second signal terminal of the fourth diode D3 is grounded.

[0027] Optionally, as Figure 2 shown, the detection circuit 100 further includes: a filtering circuit 110. The filtering circuit 110 is connected to the voltage stabilizing circuit 120 and is used to filter the detected voltage V. Specifically, in this embodiment, the detection circuit 100 further includes a filtering circuit 110 connected to the voltage stabilizing circuit 120, which is used to filter the detected voltage V after being regulated by the voltage stabilizing circuit 120. Based on this, the sharp noise in the detected voltage V can be effectively eliminated.

[0028] Optionally, as Figure 2 shown, the filtering circuit 110 includes: a second resistor R2 and a first capacitor C1. The first signal terminal of the second resistor R2 is connected to the voltage stabilizing circuit 120; the second signal terminal of the second resistor R2 is grounded; the first signal terminal of the first capacitor C1 is connected to the voltage stabilizing circuit 120; the second signal terminal of the first capacitor C1 is grounded. For the specific circuit connection between the second resistor R2 and the voltage stabilizing circuit 120, reference can be made to Figure 2 , which will not be elaborated in detail here. For the specific circuit connection between the first capacitor C1 and the voltage stabilizing circuit 120, reference can be made to Figure 2 , which will not be elaborated in detail here.

[0029] The present application also proposes a protection circuit 10, as Figure 1 and Figure 2 shown. Among them, in this embodiment, the protection circuit 10 includes the detection circuit 100 of any of the above embodiments. In other embodiments, the protection circuit 10 may also use other circuits with detection functions to replace the above detection circuit 100 of the present application.

[0030] The protection circuit 10 further includes: a control circuit 200. The control circuit 200 accesses the detection voltage V, and when determining that the difference between the first current of the first switch sub-circuit K1 and the second current of the second switch sub-circuit K2 is greater than a preset threshold based on the detection voltage V and the reference voltage, reduces the total power P of the switch circuit 30.

[0031] Specifically, in this embodiment, the detection circuit 100 is connected to the control circuit 200. The control circuit 200 accesses the detection voltage V, and determines whether the difference between the first current of the first switch sub-circuit K1 and the second current of the second switch sub-circuit K2 is greater than a preset threshold based on the relationship between the detection voltage V and the reference voltage. As described above, the detection voltage V is directly proportional to the difference between the first current and the second current. Therefore, there is a unique corresponding proportional relationship between the reference voltage and the preset threshold. When the detection voltage V is greater than the reference voltage, it indicates that the difference between the first current and the second current is greater than the preset threshold, and it can be determined that there is an uneven current sharing phenomenon between the first switch sub-circuit K1 and the second switch sub-circuit K2. Based on this, the control circuit 200 reduces the total power P of the switch circuit 30, effectively preventing the first switch sub-circuit K1 and the second switch sub-circuit K2 from operating at a high load under the condition of uneven current sharing, thereby effectively improving the service life of the first switch sub-circuit K1 and the second switch sub-circuit K2. Among them, the total power P of the switch circuit 30 is the sum of the powers acting on the first switch sub-circuit K1 and the second switch sub-circuit K2. The protection circuit 10 determines that when the first switch sub-circuit K1 and the second switch sub-circuit K2 operate under the condition of uneven current sharing through the above method, directly reduces the total power P, based on this effectively ensuring that the powers in the first switch sub-circuit K1 and the second switch sub-circuit K2 are reduced, thereby effectively protecting the first switch sub-circuit K1 and the second switch sub-circuit K2.

[0032] On the contrary, if the detection voltage V is not greater than the reference voltage, it indicates that the difference between the first current and the second current is not greater than the preset threshold, and it can be determined that there is no uneven current sharing phenomenon between the first switch sub-circuit K1 and the second switch sub-circuit K2.

[0033] Optionally, in practical applications, the user sets the magnitude of the reference voltage according to actual needs, which will not be elaborated in detail here.

[0034] Optionally, the preset threshold is greater than or equal to 0 and less than or equal to the first upper limit value. For example, in this embodiment, both the first switching sub-circuit K1 and the second switching sub-circuit K2 are SiC switching tubes. Therefore, the first switching sub-circuit K1 and the second switching sub-circuit K2 need to operate under full current sharing. At this time, the preset threshold can be set to 0. Based on this, as long as the first current and the second current are not equal, the protection circuit 10 will reduce the total power P of the switching circuit 30. Among them, the first upper limit value can be determined according to the specific types of the first switching sub-circuit K1 and the second switching sub-circuit K2, which will not be elaborated in detail here.

[0035] This application also proposes a switching circuit 30. The switching circuit 30 includes the protection circuit 10 described in any of the above embodiments. The switching circuit 30 further includes a first switching sub-circuit K1 and a second switching sub-circuit K2 connected in parallel with each other. Optionally, the first switching sub-circuit K1 includes an SiC switching tube. The second switching sub-circuit K2 includes an SiC switching tube. Specifically, in this embodiment, both the first switching sub-circuit K1 and the second switching sub-circuit K2 are SiC switching tubes. In other embodiments, any one of the first switching sub-circuit K1 and the second switching sub-circuit K2 is a switching tube of other types, which will not be elaborated in detail here.

[0036] This application also proposes a power supply circuit 20. The power supply circuit 20 includes the switching circuit 30 described in any of the above embodiments. The power supply circuit 20 further includes a power supply connected to the switching circuit 30. Among them, the power supply is used to output the total power P.

[0037] In summary, the detection circuit 100 of this application includes a first inductor L1, a second inductor L2, and a third inductor L3. Among them, the first inductor L1 is used to generate a first magnetic field based on the first current, the second inductor L2 is used to generate a second magnetic field based on the second current, and the third inductor L3 generates a detection voltage V that can reflect the magnitude relationship between the first current and the second current based on the combined magnetic field of the first magnetic field and the second magnetic field. Based on this, the detection circuit 100 can generate the detection voltage V that can reflect the current relationship between the first switching sub-circuit K1 and the second switching sub-circuit K2 through the first inductor L1, the second inductor L2, and the third inductor L3, effectively simplifying the circuit structure of the detection circuit 100, thereby effectively reducing the cost of the detection circuit 100.

[0038] Further, the present application also proposes a protection circuit 10. Different from the prior art, the protection circuit 10 of the present application includes a detection circuit 100 and a control circuit 200. The control circuit 200 is connected to a detection voltage V, and when it determines that the difference between the first current of the first switch sub-circuit K1 and the second current of the second switch sub-circuit K2 is greater than a preset threshold based on the detection voltage V and a reference voltage, it reduces the total power P of the switch circuit 30. Based on this, when the control circuit 200 determines that there is an uneven current sharing phenomenon between the first switch sub-circuit K1 and the second switch sub-circuit K2 in the above manner, the control circuit 200 reduces the total power P of the switch circuit 30, effectively preventing the first switch sub-circuit K1 and the second switch sub-circuit K2 from operating at a high load under the uneven current sharing condition, thereby effectively improving the service life of the first switch sub-circuit K1 and the second switch sub-circuit K2.

[0039] Wherein, when the protection circuit 10 determines that the first switch sub-circuit K1 and the second switch sub-circuit K2 are operating under the uneven current sharing condition in the above manner, it directly reduces the total power P. Based on this, it effectively ensures that the power in the first switch sub-circuit K1 and the second switch sub-circuit K2 is reduced, thereby effectively protecting the first switch sub-circuit K1 and the second switch sub-circuit K2.

[0040] It should be noted that in the accompanying drawings herein, they are only for showing the structural relationship and connection relationship of the inventive products of the present application, and do not thereby limit the specific structural dimensions of the inventive products of the present application.

[0041] The above are only the embodiments of the present invention, and do not thereby limit the patent scope of the present invention. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A detection circuit, characterized in that, For a switching circuit, the switching circuit includes a first switching sub-circuit and a second switching sub-circuit connected in parallel with each other, and the detection circuit includes: A first inductor, connected to the first switching sub-circuit, for generating a first magnetic field based on a first current of the first switching sub-circuit; A second inductor, connected to the second switching sub-circuit, for generating a second magnetic field based on a second current of the second switching sub-circuit; A third inductor, the third inductor generating a detection voltage based on a combined magnetic field of the first magnetic field and the second magnetic field; wherein, the first magnetic field and the second magnetic field are opposite to each other.

2. The detection circuit according to claim 1, wherein The detection circuit includes: a voltage stabilizing circuit, connected to the third inductor.

3. The detection circuit according to claim 2, characterized in that, The voltage stabilizing circuit includes: A first resistor, a first signal terminal of which is connected to a first signal terminal of the third inductor, and a second signal terminal of the first resistor is connected to a second signal terminal of the third inductor; A first diode, a first signal terminal of which is connected to the first signal terminal of the first resistor; A second diode, a first signal terminal of which is connected to the first signal terminal of the first diode, and a second signal terminal of the second diode is grounded; A third diode, a first signal terminal of which is connected to the second signal terminal of the first resistor, and a second signal terminal of the third diode is connected to a second signal terminal of the first diode; A fourth diode, a first signal terminal of which is connected to the first signal terminal of the third diode, and a second signal terminal of the fourth diode is grounded.

4. The detection circuit according to claim 2, wherein The detection circuit includes: A filtering circuit, connected to the voltage stabilizing circuit, for filtering the filtering circuit after voltage stabilization processing by the voltage stabilizing circuit.

5. The detection circuit according to claim 4, wherein The filtering circuit includes: A second resistor, a first signal terminal of which is connected to the voltage stabilizing circuit; the second signal terminal of the second resistor is grounded; A first capacitor, a first signal terminal of which is connected to the voltage stabilizing circuit; the second signal terminal of the first capacitor is grounded.

6. A protection circuit, characterized in that, The protection circuit includes the detection circuit according to any one of claims 1-5, and the protection circuit further includes: A control circuit, accessing the detection voltage, and reducing the total power of the switching circuit when determining that the difference between the first current of the first switching sub-circuit and the second current of the second switching sub-circuit is greater than a preset threshold based on the detection voltage and a reference voltage.

7. The protection circuit according to claim 6, wherein The preset threshold is greater than or equal to 0 and less than or equal to a first upper limit value.

8. A switching circuit, characterized in that, The switching circuit includes the protection circuit according to any one of claims 1-7, and the switching circuit further includes the first switching sub-circuit and the second switching sub-circuit connected in parallel with each other.

9. The switching circuit according to claim 8, wherein The first switching sub-circuit includes a SiC switch tube; and / or the second switching sub-circuit includes a SiC switch tube.

10. A power supply circuit, characterized in that, The power supply circuit includes the switching circuit according to any one of claims 8-9, and the power supply circuit further includes a power supply, which is connected to the switching circuit.

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