Short-circuit protection circuit, power circuit and power electronic equipment

Abstract

The invention provides a short-circuit protection circuit, a power circuit and power electronic equipment. The short-circuit protection circuit can comprise a voltage dividing module, a voltage stabilizing module and a judging module. The voltage dividing module is used for outputting working current to the voltage stabilizing module according to the first working voltage. The voltage stabilization module is used for outputting a second working voltage to the judgment module according to the working current. The judgment module is used for outputting a short-circuit protection signal according to the second working voltage. According to the short-circuit protection circuit, the voltage stabilizing module is arranged to control the short-circuit protection time, compared with the prior art that the short-circuit protection time is controlled by adopting a clock signal, the cost of the short-circuit protection circuit is greatly reduced, and short-circuit protection false triggering of the driven power tube in the opening transient state can be thoroughly avoided; and the reliability of the short-circuit protection circuit is improved.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to a short-circuit protection circuit, a power circuit, and a power electronic device. Background Technology

[0002] Insulated-gate bipolar transistors (IGBTs), as representative high-power turn-off power electronic devices, are the core of power electronic devices and have broad future development prospects. IGBTs combine the advantages of bipolar junction transistors (BJTs) and field-effect transistors (FETs), featuring low on-state voltage drop and high switching speed. While achieving efficient power conversion, IGBTs are highly susceptible to instantaneous damage due to the huge current generated by short circuits. Therefore, short-circuit protection for IGBTs is necessary.

[0003] Related technologies typically compare the voltage between the collector and emitter of the IGBT with a reference voltage to achieve short-circuit protection. However, the short-circuit protection time is affected by the bus voltage. As the bus voltage increases, the short-circuit protection time decreases, and the IGBT's turn-on time increases. In other words, the IGBT's short-circuit protection time is shorter than its turn-on time, which can lead to the risk of the IGBT falsely triggering short-circuit protection when operating under high voltage and high current. In other words, the reliability of the short-circuit protection circuit is relatively low. Summary of the Invention

[0004] To address the issue of low reliability in existing technologies, this application provides a short-circuit protection circuit, which may include a voltage divider module, a voltage regulator module, and a judgment module.

[0005] The voltage divider module is used to output operating current to the voltage regulator module based on the first operating voltage.

[0006] The voltage regulator module is used to output a second operating voltage to the judgment module based on the operating current.

[0007] The judgment module is used to output a short-circuit protection signal based on the second operating voltage.

[0008] Optionally, the first terminal of the voltage divider module is connected to the first electrode of the driven power transistor and is used to receive the first operating voltage. The second terminal of the voltage divider module is connected to the first terminal of the judgment module. The third terminal of the voltage divider module is connected to the first terminal of the voltage regulator module. The fourth terminal of the voltage divider module, the second terminal of the voltage regulator module, the second terminal of the judgment module, and the second electrode of the driven power transistor are connected. The control electrode of the driven power transistor is used to receive the first drive signal. The third terminal of the judgment module is used to receive the second drive signal, and the fourth terminal of the judgment module is used to output a short-circuit protection signal.

[0009] In some possible implementations, the voltage divider module includes a first voltage divider resistor, a second voltage divider resistor, and a third voltage divider resistor.

[0010] The first terminal of the first voltage divider resistor serves as the first terminal of the voltage divider module. The second terminal of the first voltage divider resistor is connected to the first terminal of the second voltage divider resistor, serving as the third terminal of the voltage divider module. The second terminal of the second voltage divider resistor is connected to the first terminal of the third voltage divider resistor, serving as the second terminal of the voltage divider module. The second terminal of the third voltage divider resistor serves as the fourth terminal of the voltage divider module.

[0011] In some other possible implementations, the voltage regulator module includes a Zener diode. The cathode of the Zener diode serves as the first terminal of the voltage regulator module, and the cathode of the Zener diode serves as the second terminal of the voltage regulator module.

[0012] In some other possible implementations, the decision module includes an inverter, a first power transistor, a timing capacitor, and a comparator.

[0013] The input terminal of the inverter serves as the third terminal of the judgment module, and the output terminal of the inverter is connected to the control terminal of the first power transistor. The first terminal of the first power transistor, the first terminal of the timing capacitor, and the inverting input terminal of the comparator are connected, serving as the first terminal of the judgment module. The second terminal of the timing capacitor is connected to the second terminal of the first power transistor, serving as the second terminal of the judgment module. The non-inverting input terminal of the comparator is used to receive the reference voltage, and the output terminal of the comparator is used to output a short-circuit protection signal.

[0014] For example, a short-circuit protection circuit is used for: When the first drive signal is used to indicate that the driven power transistor is turned off, the first power transistor is controlled to turn on. The short-circuit protection signal is used to indicate that no short-circuit fault has occurred in the power circuit where the driven power transistor is located.

[0015] Optionally, the short-circuit protection circuit is used to: control the first power transistor to turn off when the first drive signal indicates that the driven power transistor is on, in the following cases: If the second operating voltage does not exceed the preset voltage threshold, the short-circuit protection signal is used to indicate that no short-circuit fault has occurred in the power circuit where the driven power transistor is located.

[0016] If the second operating voltage exceeds the preset voltage threshold, the short-circuit protection signal is used to indicate that a short-circuit fault has occurred in the power circuit where the driven power transistor is located.

[0017] Optionally, the first power transistor may be a bipolar transistor or an insulated-gate field-effect transistor.

[0018] Furthermore, this application also provides a power circuit, which may include a driven power transistor and the aforementioned short-circuit protection circuit. The driven power transistor is connected to the short-circuit protection circuit.

[0019] Furthermore, this application also provides a power electronic device that may include the aforementioned power circuit.

[0020] Compared with the prior art, the beneficial effects of this application are as follows: The short-circuit protection circuit provided in this application may include a voltage divider module, a voltage regulator module, and a judgment module. The voltage divider module outputs an operating current to the voltage regulator module based on a first operating voltage. The voltage regulator module outputs a second operating voltage to the judgment module based on the operating current. The judgment module outputs a short-circuit protection signal based on the second operating voltage. By setting the voltage regulator module, this application can control the short-circuit protection time. Compared with related technologies that use clock signals to control the short-circuit protection time, this application significantly reduces the cost of the short-circuit protection circuit and can completely avoid false triggering of short-circuit protection by the driven power transistor during the turn-on transient, thereby improving the reliability of the short-circuit protection circuit.

[0021] This application uses a voltage divider circuit to avoid the risk of high-voltage breakdown caused by using the operating voltage of the driven power transistor as the input signal, and can reduce the operating current of the Zener diode to a negligible level, thus avoiding affecting the normal operation of the driven power transistor.

[0022] This application can reduce the static resistance loss when the driven power transistor is turned off by adjusting the resistance values ​​of the first, second, and third voltage divider resistors; and the first, second, and third voltage divider resistors can reduce the operating voltage levels of the timing capacitor, the first power transistor, the comparator, and the inverter, thereby reducing the cost of the short-circuit protection circuit and improving the safety of the power circuit in which the short-circuit protection circuit is located.

[0023] This application uses a comparator to detect short-circuit protection signals, which results in short judgment time and low cost. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic structural diagram of a short-circuit protection circuit in an embodiment of this application; Figure 2 This is a schematic structural diagram of a power circuit in an embodiment of this application. Detailed Implementation

[0026] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0027] The terms "first," "second," etc., used in the specification, embodiments, claims, and drawings of this application are for distinguishing purposes only and should not be construed as indicating or implying relative importance or order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or units. A method, system, product, or apparatus is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0028] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0029] This application provides a short-circuit protection circuit for driving a power transistor. The driven power transistor can be an insulated-gate bipolar transistor (IGBT) or similar. This application uses driving an IGBT as an example for illustration.

[0030] like Figure 1As shown. The short-circuit protection circuit 10 may include a voltage divider module 1, a voltage regulator module 2, and a judgment module 3.

[0031] Voltage divider module 1 is used to output operating current to voltage regulator module 2 according to the first operating voltage V1.

[0032] The voltage regulator module 2 is used to output a second working voltage V2 to the judgment module 3 based on the working current.

[0033] The judgment module 3 is used to output a short-circuit protection signal based on the second working voltage V2.

[0034] Optional, see reference Figure 1 The first end of voltage divider module 1 (i.e. Figure 1 The left end of the first voltage divider resistor R1 is connected to the first terminal (which can be the collector) of the driven power transistor (i.e., IGBT) and is used to receive the first operating voltage V1. The second terminal of the voltage divider module 1 (i.e., Figure 1 The right end of the second voltage divider resistor R2 is connected to the first end of the judgment module 3. The third end of the voltage divider module 1 (i.e., Figure 1 The right end of the first voltage divider resistor R1 and the left end of the second voltage divider resistor R2 are connected to the first terminal of the voltage regulator module 3. The fourth terminal of the voltage divider module 1 (i.e. Figure 1 The lower end of the third voltage divider resistor R3), the second end of the voltage regulator module 2, and the second end of the judgment module 3 (i.e., Figure 1 The upper end of the timing capacitor C1, the first terminal of the first power transistor Q1, and the second terminal (which can be the emitter) of the driven power transistor (i.e., IGBT) are connected. The control stage of the driven power transistor (i.e., IGBT) is used to receive the first drive signal DS1. The third terminal of the judgment module 3 (i.e., Figure 1 The input terminal of inverter N is used to receive the second drive signal DS2, and the fourth terminal of the judgment module 3 (i.e. Figure 1 The output of the comparator Com is used to output a short-circuit protection signal.

[0035] Among some possible implementations, refer to Figure 1 The voltage divider module 1 includes a first voltage divider resistor R1, a second voltage divider resistor R2, and a third voltage divider resistor R3.

[0036] The first terminal of the first voltage divider resistor R1 serves as the first terminal of the voltage divider module 1. The second terminal of the first voltage divider resistor R1 is connected to the first terminal of the second voltage divider resistor R2, serving as the third terminal of the voltage divider module 1. The second terminal of the second voltage divider resistor R2 is connected to the first terminal of the third voltage divider resistor R3, serving as the second terminal of the voltage divider module 1. The second terminal of the third voltage divider resistor R3 serves as the fourth terminal of the voltage divider module 1.

[0037] In other possible implementations, please refer to... Figure 1The voltage regulator module 2 includes a Zener diode (TVS). The cathode of the Zener diode (TVS) serves as the first terminal of the voltage regulator module 2, and the cathode of the Zener diode (D2) serves as the second terminal of the voltage regulator module 2.

[0038] Among the other possible implementations, continue to refer to Figure 1 The judgment module 3 includes an inverter N, a first power transistor Q1, a timing capacitor C1, and a comparator Com. The first power transistor Q1 is a transistor or an insulated-gate field-effect transistor, etc. In the embodiments of this application, the first power transistor Q1 is an insulated-gate field-effect transistor, i.e., a MOSFET.

[0039] The input terminal of inverter N serves as the third terminal of judgment module 3, and the output terminal of inverter N is connected to the control terminal of the first power transistor Q1. The first terminal (which can be the drain) of the first power transistor Q1, the first terminal of the timing capacitor C1, and the inverting input terminal of comparator Com are connected, serving as the first terminal of judgment module 3. The second terminal of the timing capacitor C1 is connected to the second terminal of the first power transistor Q1, serving as the second terminal of judgment module 3. The non-inverting input terminal of comparator Com is used to receive the reference voltage V. REF The output of comparator Com is used to output a short-circuit protection signal.

[0040] For example, the short-circuit protection circuit 10 is used for: When the first drive signal DS1 indicates that the driven power transistor is off (the first drive signal DS1 can be low), the first power transistor Q1 is turned on. The second operating voltage V2 is always 0, and the short-circuit protection signal is always high, indicating that no short-circuit fault has occurred in the power circuit where the driven power transistor is located. By properly setting the resistance ratio of the first voltage divider resistor R1 and the second voltage divider resistor R2, the Zener diode TVS can be broken down within the range of bus voltage variation. The short-circuit protection signal is used to indicate that no short-circuit fault has occurred in the power circuit where the driven power transistor is located.

[0041] Optionally, the short-circuit protection circuit is used to control the first power transistor Q1 to turn off when the first drive signal DS1 indicates that the driven power transistor is turned on (the first drive signal DS1 can be high level).

[0042] Specifically, the following situations can be identified: If the second operating voltage V2 does not exceed the preset voltage threshold, the short-circuit protection signal is used to indicate that no short-circuit fault has occurred in the power circuit where the driven power transistor is located. It is conceivable that during this process, the second operating voltage V2 will first rise and then fall.

[0043] If the second operating voltage V2 exceeds a preset voltage threshold, a short-circuit protection signal is used to indicate a short-circuit fault in the power circuit where the driven power transistor is located. It is conceivable that during this process, the second operating voltage V2 will only increase.

[0044] The collector voltage of the IGBT takes a certain amount of time to drop, and the voltage across the timing capacitor C1 begins to rise. This can be achieved by setting a reasonable reference voltage V. REF This ensures that when the circuit is turned on under normal operating conditions, the peak voltage of the timing capacitor C1 is always lower than the reference voltage V. REF In effect, this is equivalent to setting the same blanking time (i.e., short-circuit protection time), which can effectively avoid false triggering of short-circuit protection. If a Class I short-circuit protection occurs at this time, the bus voltage will not drop normally and remain unchanged after the IGBT is turned on. Since the Zener diode TVS clamps the midpoint voltage, and the charging rate on the timing capacitor C1 depends on the Zener diode TVS voltage, the resistance values ​​of the second voltage divider resistor R2 and the third voltage divider resistor R3, and the capacitance value of the timing capacitor C1, the voltage rise curve of the timing capacitor C1 is consistent. It can be seen that the trigger time of Class I short-circuit protection is the same. In other words, the short-circuit protection time provided in this application embodiment is fixed.

[0045] If a Class II short circuit occurs when the IGBT is turned on for an extended period, the collector-emitter voltage of the IGBT will rapidly rise to the bus voltage. Similarly, due to the voltage clamping effect of the Zener diode TVS, the voltage rise curve of the timing capacitor C1 will be consistent, and the short circuit protection time will be the same for different bus voltage values.

[0046] When the IGBT changes from being turned on to being turned off, the first power transistor Q1 turns on transiently, making it impossible to trigger the short-circuit protection.

[0047] This application also provides a power circuit in its embodiments. For example... Figure 2 As shown, the power circuit 100 may include a driven power transistor (IGBT) and the aforementioned short-circuit protection circuit 10. The driven power transistor is connected to the short-circuit protection circuit 10. Of course, the power circuit may also include other components, which are not limited in this embodiment.

[0048] This application also provides a power electronic device that may include the power circuit described above. Of course, the power electronic device may also include other components, and this application does not limit its scope.

[0049] The above are merely embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application shall be included within the scope of the claims of this application pending approval.

Claims

1. A short-circuit protection circuit, characterized in that, It includes a voltage divider module, a voltage regulator module, and a judgment module; The voltage divider module is used to: output a working current to the voltage regulator module according to the first working voltage; The voltage regulator module is used to: output a second operating voltage to the judgment module according to the operating current; The judgment module is used to output a short-circuit protection signal based on the second operating voltage.

2. The short-circuit protection circuit according to claim 1, characterized in that, The first terminal of the voltage divider module is connected to the first electrode of the driven power transistor and is used to receive the first operating voltage; the second terminal of the voltage divider module is connected to the first terminal of the judgment module; the third terminal of the voltage divider module is connected to the first terminal of the voltage regulator module; the fourth terminal of the voltage divider module, the second terminal of the voltage regulator module, the second terminal of the judgment module, and the second electrode of the driven power transistor are connected; the control electrode of the driven power transistor is used to receive a first driving signal; the third terminal of the judgment module is used to receive a second driving signal; and the fourth terminal of the judgment module is used to output the short-circuit protection signal.

3. The short-circuit protection circuit according to claim 2, characterized in that, The voltage divider module includes a first voltage divider resistor, a second voltage divider resistor, and a third voltage divider resistor; The first end of the first voltage divider resistor serves as the first end of the voltage divider module; the second end of the first voltage divider resistor is connected to the first end of the second voltage divider resistor, serving as the third end of the voltage divider module; the second end of the second voltage divider resistor is connected to the first end of the third voltage divider resistor, serving as the second end of the voltage divider module; and the second end of the third voltage divider resistor serves as the fourth end of the voltage divider module.

4. The short-circuit protection circuit according to claim 2, characterized in that, The voltage regulator module includes a Zener diode; the cathode of the Zener diode serves as the first terminal of the voltage regulator module, and the cathode of the Zener diode serves as the second terminal of the voltage regulator module.

5. The short-circuit protection circuit according to claim 2, characterized in that, The judgment module includes an inverter, a first power transistor, a timing capacitor, and a comparator; The input terminal of the inverter serves as the third terminal of the judgment module, and the output terminal of the inverter is connected to the control terminal of the first power transistor. The first terminal of the first power transistor, the first terminal of the timing capacitor, and the inverting input terminal of the comparator are connected to serve as the first terminal of the judgment module. The second terminal of the timing capacitor is connected to the second terminal of the first power transistor to serve as the second terminal of the judgment module. The non-inverting input terminal of the comparator is used to receive the reference voltage, and the output terminal of the comparator is used to output the short-circuit protection signal.

6. The short-circuit protection circuit according to claim 5, characterized in that, The short-circuit protection circuit is used for: When the first drive signal is used to indicate that the driven power transistor is turned off, the first power transistor is controlled to be turned on, and the short-circuit protection signal is used to indicate that no short-circuit fault has occurred in the power circuit where the driven power transistor is located.

7. The short-circuit protection circuit according to claim 5, characterized in that, The short-circuit protection circuit is used to control the first power transistor to turn off when the first drive signal indicates that the driven power transistor is on, and the following situations apply: If the second operating voltage does not exceed the preset voltage threshold, the short-circuit protection signal is used to indicate that no short-circuit fault has occurred in the power circuit where the driven power transistor is located; If the second operating voltage exceeds a preset voltage threshold, the short-circuit protection signal is used to indicate that a short-circuit fault has occurred in the power circuit where the driven power transistor is located.

8. The short-circuit protection circuit according to any one of claims 5 to 7, characterized in that, The first power transistor is a bipolar transistor or an insulated-gate field-effect transistor.

9. A power circuit, characterized in that, It includes a driven power transistor and a short-circuit protection circuit as described in any one of claims 1 to 8; the driven power transistor is connected to the short-circuit protection circuit.

10. A power electronic device, characterized in that, Includes the power circuit as described in claim 9.

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