Power supply overcurrent protection circuit and electronic equipment

Abstract

The invention provides a power supply overcurrent protection circuit and electronic equipment, and the power supply overcurrent protection circuit comprises a power supply loop which comprises a power supply, at least one switching tube and a load which are sequentially connected in series, a first current detection circuit, a second current detection circuit, a first control circuit and a second control circuit, comprising a first current sensor connected in series to the power supply loop and configured to detect a current of the power supply loop; the trigger circuit is electrically connected to a first node corresponding to the first sensing output end of the first current sensor, the negative electrode of the power supply and the output end of the driving circuit, and is configured to turn off the corresponding switching tube based on the detected current; the second current detection circuit is configured to detect the current of the power supply loop and transmit the current to the control unit, and the control unit is configured to control the driving circuit to stop outputting based on the received signal. According to the embodiment of the invention, rapid overcurrent protection can be realized with relatively low power consumption.

Description

Technical Field

[0001] The present disclosure relates to the technical field of power supply, and in particular to a power supply overcurrent protection circuit and electronic equipment. Background Art

[0002] Currently in high-voltage and high-power pulse power supplies, in the case of a high-voltage rapid short circuit, tens of kiloamperes of instantaneous current will be generated, which can easily cause damage to other components in the system. Therefore, a reliable overcurrent protection circuit is crucial to the stable and reliable operation of the system.

[0003] Currently, there are two approaches: drive protection and overcurrent protection to achieve the purpose of protection after overcurrent.

[0004] A common driver protection scheme is to detect the voltage across the driver tube and cut off the gate drive pulse when the tube voltage drop exceeds the threshold. This method has a long response time and is prone to damage to high-power devices, and the protection effect is easily affected by temperature.

[0005] The common overcurrent protection scheme is to use a sampling resistor to collect current and then use the signal processor MCU to determine whether the current signal exceeds the threshold. When the current signal exceeds the protection threshold, the corresponding protection signal is output or a protection action is taken. However, under high current conditions, the sampling resistor will produce a large power loss and reduce the system output efficiency; and the current processing of the signal processor has a certain delay, which is prone to untimely protection, causing premature aging or even damage of power devices.

[0006] Therefore, a solution is needed that can effectively and timely protect the power supply from overcurrent. Summary of the invention

[0007] In order to solve at least one of the above problems, the present disclosure provides a power supply overcurrent protection circuit, including: a power supply circuit, at least one first current sampling circuit and at least one trigger circuit arranged in a one-to-one correspondence, a second current sampling circuit, a drive circuit, and a control unit.

[0008] The power supply circuit includes: a power supply, at least one switch tube and a load connected in series in sequence, wherein the switch tube, the first current sampling circuit and the trigger circuit are arranged in a one-to-one correspondence.

[0009] A first current detection circuit includes a first current sensor connected in series between the load and the corresponding switch tube, and is configured to detect the current of the power supply loop;

[0010] A trigger circuit, electrically connected to a first node corresponding to a first sensing output terminal of the first current sensor, a negative electrode of a power supply, and an output terminal of the driving circuit, and configured to turn off a corresponding switch tube based on the detected current;

[0011] The second current detection circuit includes a second current sensor connected in series between at least one switch tube in series and the negative electrode, configured to detect the current of the power supply circuit and transmit it to the control unit,

[0012] The control unit is configured to control the driving circuit to stop output based on the received detection signal.

[0013] Optionally, the first current detection circuit further includes: a first resistor, wherein:

[0014] The first input terminal of the first current sensor is electrically connected to the load, the second input terminal is electrically connected to the first pole of the corresponding switch tube, the first sensing output terminal is electrically connected to the first end of the first resistor, and the second sensing output terminal is electrically connected to the second end of the first resistor and electrically connected to the negative pole of the power supply.

[0015] Optionally, the trigger circuit includes: a first transistor, a second resistor, a third resistor and a fourth resistor,

[0016] The first electrode of the first transistor is electrically connected to the control electrode of the corresponding switch tube, the second electrode is electrically connected to the negative electrode of the power supply, and the control electrode is electrically connected to the first end of the third resistor.

[0017] The first end of the second resistor is electrically connected to the first node, the second end is electrically connected to the first end of the third resistor, the second end of the third resistor is electrically connected to the first end of the fourth resistor, and the second end of the fourth resistor is electrically connected to the negative electrode of the power supply.

[0018] Optionally, the trigger circuit further includes: a fifth resistor and a sixth resistor connected in series,

[0019] A first end of the fifth resistor is electrically connected to the first output end of the driving circuit, and a second end of the sixth resistor is electrically connected to the first end of the fourth resistor.

[0020] Optionally, the trigger circuit further includes: a first voltage suppression diode, a second voltage suppression diode,

[0021] The first electrode of the first voltage suppression diode is electrically connected to the second end of the fifth resistor, and the second electrode is electrically connected to the negative electrode of the power supply.

[0022] A first electrode of the second voltage suppression diode is electrically connected to a control electrode of a corresponding switch tube, and a second electrode is electrically connected to a negative electrode of a power source.

[0023] Optionally, the trigger circuit further includes: a third diode, and a seventh resistor and an eighth resistor connected in series,

[0024] The first end of the seventh resistor is electrically connected to the first output end of the driving circuit, the connection end of the seventh resistor and the eighth resistor is electrically connected to the first electrode of the first transistor, and the second end of the eighth resistor is electrically connected to the control electrode of the corresponding switch tube.

[0025] The third diode has an anode electrically connected to the second electrode of the first transistor, and a cathode electrically connected to the negative electrode of the load.

[0026] Optionally, the second current detection circuit further includes: a ninth resistor, a tenth resistor and an eleventh resistor,

[0027] The first input terminal of the second current sensor is electrically connected to the second electrode of the switch tube close to the negative electrode of the power supply in at least one switch tube connected in series, and the second input terminal is electrically connected to the negative electrode of the power supply.

[0028] Two ends of the ninth resistor are electrically connected to the first sensing output terminal and the second sensing output terminal of the second current sensor.

[0029] The first end of the tenth resistor is electrically connected to the first sensing output end of the second current sensor, the second end is electrically connected to the first end of the eleventh resistor and electrically connected to the first end of the control unit, and the second end of the eleventh resistor is electrically connected to the second end of the control unit to detect the current of the power supply circuit.

[0030] Optionally, the control unit obtains the current of the power supply circuit based on the signals received by the first end and the second end, and when it is determined that the obtained current is greater than a preset threshold, the drive circuit is controlled to stop output.

[0031] Optionally, the first current detection circuit, the trigger circuit, and the switch tube are all multiple,

[0032] The power overcurrent protection circuit also includes an isolation transformer, which is arranged between the drive circuit and the trigger circuit.

[0033] The isolation transformer includes a primary coil electrically connected to the output end of the driving circuit and multiple secondary coils arranged one by one corresponding to multiple trigger circuits. The first pole of each secondary coil is electrically connected to the corresponding trigger circuit, and the second pole is electrically connected to the negative pole of the power supply.

[0034] A second aspect of the present disclosure provides an electronic device, comprising the power overcurrent protection circuit described above.

[0035] The beneficial effects of the present disclosure are as follows:

[0036] In response to the existing problems, the present invention develops a power supply overcurrent protection circuit and electronic equipment, which senses the current of the power supply circuit through a first current sensor connected in series in the power supply circuit, and uses a trigger circuit to quickly control the switch tube to shut down based on the current. At the same time, the second current sensor detects the power supply current and transmits it to the control unit for software processing, thereby realizing dual overcurrent protection of hardware and software, avoiding the problem that the pure hardware circuit cannot maintain the repeated startup of the overcurrent fault, and realizing low-power, fast and effective overcurrent protection, which has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 A schematic block diagram of a power supply overcurrent protection circuit according to an embodiment of the present disclosure is shown;

[0039] Figure 2 A schematic circuit diagram of a power supply overcurrent protection circuit according to an embodiment of the present disclosure is shown;

[0040] Figure 3 An equivalent circuit schematic diagram of a trigger circuit of a power supply overcurrent protection circuit according to an embodiment of the present disclosure is shown;

[0041] Figure 4 Show Figure 2 The simulation diagram of the power supply overcurrent protection circuit shown;

[0042] Figure 5 A schematic block diagram of a power supply overcurrent protection circuit according to another embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0043] In order to more clearly illustrate the present disclosure, the present disclosure is further described below in conjunction with preferred embodiments and drawings. Similar components in the drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the content described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present disclosure.

[0044] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, similar words such as "one", "one" or "the" do not indicate a quantitative limit, but indicate that there is at least one. "Include" or "comprises" and other similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and other similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0045] In the present disclosure, "electrical connection" includes the case where components are connected together through an element having some kind of electrical function. There is no particular limitation on the "element having some kind of electrical function" as long as it can transmit and receive electrical signals between the connected components. Examples of "element having some kind of electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other elements having various functions.

[0046] As used in the present disclosure, "parallel", "perpendicular", and "equal" include the conditions described and conditions similar to the conditions described, the range of which is within an acceptable range of deviations, wherein the acceptable range of deviations is determined by a person of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "equal" includes absolute equality and approximate equality, wherein the acceptable range of deviations for approximate equality may include, for example, a difference between the two being equal that is less than or equal to 5% of either.

[0047] Reference Figure 1 As shown, the embodiment of the present disclosure provides a power supply overcurrent protection circuit, including: a power supply circuit 11, at least one first current detection circuit 12 and at least one trigger circuit 13, a second current detection circuit 14, a drive circuit 15, and a control unit 16.

[0048] The power supply circuit 11 includes: a power supply, at least one switch tube Q and a load RL connected in series in sequence, the switch tube Q, the first current sampling circuit 12 and the trigger circuit 13 are arranged in a one-to-one correspondence.

[0049] The first current detection circuit 12 includes a first current sensor connected in series between the load RL and the corresponding switch tube Q, and is configured to detect the current of the power supply circuit;

[0050] The trigger circuit 13 is electrically connected to a first node corresponding to the first sensing output terminal of the first current sensor, the negative electrode of the power supply, and the output terminal of the driving circuit 15, and is configured to turn off the corresponding switch tube Q based on the detected current;

[0051] The second current detection circuit 14 includes a second current sensor connected in series between at least one switch tube in series and the negative electrode, and is configured to detect the current of the power supply circuit 11 and transmit it to the control unit 16.

[0052] The control unit 16 is configured to control the driving circuit 15 to stop output based on the received detection signal.

[0053] In this embodiment, the current of the power supply circuit is sensed by a first current sensor connected in series in the power supply circuit, and a trigger circuit is used to quickly control the switch tube to shut down based on the current. At the same time, the second current sensor detects the power supply current and transmits it to the control unit for software processing, thereby realizing dual overcurrent protection of hardware and software, avoiding the problem that a pure hardware circuit cannot maintain repeated startup of an overcurrent fault, and realizing low-power, fast and effective overcurrent protection.

[0054] Refer to the following Figures 1 to 4 The embodiments of the present disclosure are described in detail with reference to specific examples.

[0055] In a specific example, combining Figure 1 and Figure 2 As shown, the power overcurrent protection circuit includes a power supply circuit 11, a first overcurrent detection circuit 12, a trigger circuit 13, a second current detection circuit 14, a drive circuit 15 and a control unit 16.

[0056] Among them, the power supply circuit 11 includes, for example: a power supply V7 connected in series, a switch tube Q1 and a load RL. In the embodiment of the present disclosure, the switch tube Q1 is a power semiconductor device IGBT. In actual application, without considering the power switching capacity, the switch tube Q1 can also use a MOS tube. In addition, the conductivity type of the switch tube Q1 is N-type. Exemplarily, the power supply V7 can be a high-voltage and high-power pulse power supply, and the pulse generated by the power supply V7 supplies power to the load RL. At this time, the switch tube Q1 is a power device IGBT that controls the power supply path from the power supply V7 to the load RL. In addition, exemplarily, the power supply V7 can form a high-voltage and high-power pulse power supply with the switch tube Q1 to supply power to the load RL. At this time, the power supply V7 refers to the power supply constituting the pulse power supply, and the switch tube Q1 represents the driving power device IGBT of the pulse power supply. It should be understood that the above configurations are all protected by the power supply circuit 11 of the present disclosure.

[0057] It should be noted that when there is no need to distinguish the number of switch tubes, they are collectively referred to as switch tubes Q, and when they need to be distinguished, one switch tube is referred to as switch tube Q1.

[0058] Continue to refer to Figure 1 and Figure 2As shown, the first current detection circuit 12 is configured to detect the current of the power supply circuit 11, which is also the current flowing through the switch tube Q1. Specifically in this example, the first current detection circuit 12 is configured to sample the pulse current of the pulse power supply. The first current detection circuit 12 includes a first current sensor TA1 connected in series between the load RL and the switch tube Q1. The present disclosure is not intended to limit the type of the first current sensor TA1. As long as it can sense a certain proportion of the current flowing through the power supply circuit 11 sensed by it through electromagnetic mutual induction to the current sensor at the sensing output end, through this setting, the power loss can be small when sensing large currents up to kiloamperes in the power supply circuit 11, thereby improving the system output efficiency of the pulse power supply. Of course, Figure 2 The sensing ratio of the first current sensor TA1 is shown to be 1:100, but this is not intended to be limiting and can be set as required in actual applications.

[0059] In addition, by electrically connecting the first current sensor TA1 between the switch tube Q1 and the load RL, that is, the first current sensor TA1 is connected in series to the high end of the power device, it is possible to accurately sense excessive current, and to quickly sense overcurrent and turn off the switch tube Q1 when a large current flows, thereby improving the current detection accuracy and protecting the pulse power supply system.

[0060] Continue to refer to Figure 2 As shown, the first current detection circuit 12 further includes: a first resistor R1.

[0061] Specifically, the first input terminal of the first current sensor TA1 is electrically connected to the load RL, the second input terminal is electrically connected to the first pole of the switch tube Q1, the first sensing output terminal is electrically connected to the first end of the first resistor R1, and the second sensing output terminal is electrically connected to the second end of the first resistor R1 and electrically connected to the negative pole of the power supply V7. In this example, a sensing current of 1 / 100 of the current flowing through the switch tube Q1 in the power supply circuit 11 flows through the first resistor R1 and is reflected as a voltage across the first resistor R1. In addition, in this example, the negative pole of the power supply V7 is electrically connected to the common terminal COM, and the common terminal COM can be a ground terminal in a specific implementation. For ease of understanding and description below, the negative pole of the power supply V7 is referred to by the label "COM".

[0062] It should be noted that Figure 2 The equivalent circuit is only an exemplary equivalent method. In other words, if the power supply V7 is used as a power supply to supply power to the load RL, the negative electrode of the load RL can also be electrically connected to the common terminal, which is not elaborated in this article.

[0063] Continue to refer to Figure 1 and Figure 2As shown, the trigger circuit 13 is electrically connected to the first node N1 corresponding to the first sensing output terminal of the first current sensor TA1, the negative electrode COM of the power supply V7, and the output terminal of the driving circuit 15, and is configured to turn off the switch tube Q1 based on the detected current.

[0064] Specifically, refer to Figure 2 As shown, the trigger circuit 13 includes: a first transistor T1, a second resistor R2, a third resistor R3 and a fourth resistor R4.

[0065] The conductivity type of the first transistor T1 is N-type. The first electrode 3 of the first transistor T1 is electrically connected to the control electrode of the corresponding switch tube Q1, the second electrode 2 is electrically connected to the negative electrode COM of the power supply V7, and the control electrode 1 is electrically connected to the first end of the third resistor R3. In this example, the first transistor T1 is a triode, the first electrode 3 of which is the collector, the second electrode 2 is the emitter, and the control electrode 1 is the base, but the present disclosure is not intended to be limited to this, and other transistors that can be controlled to be turned on based on the potential of the control electrode are also protected by the present disclosure.

[0066] Further, the first electrode of the second resistor R2 is electrically connected to the first node N1, the second end is electrically connected to the first end of the third resistor R3, the second end of the third resistor R3 is electrically connected to the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is electrically connected to the negative electrode COM of the power supply V7. It can be seen that the second resistor R2, the third resistor R3 and the fourth resistor R4 are connected in series between the first node N1 and the negative electrode COM of the power supply V7, and the total voltage drop of the second resistor R2, the third resistor R3 and the fourth resistor R4 connected in series is the voltage drop across the first resistor R1 as a sampling resistor. The divided voltage of the third resistor R3 and the fourth resistor R4 is provided to the control electrode of the first transistor T1, and the second resistor R2 is used to share the voltage drop.

[0067] In the embodiment of the present disclosure, when the switch tube Q1 is working, the current flowing through the switch tube Q1 is collected by the first current sensor TA1, and the first resistor R1 converts 1:100 of the collected current into a voltage signal. The first resistor R1 is connected in series and parallel with the resistors of the second resistor R2, the third resistor R3 and the fourth resistor R4, which is equivalent to sampling a small current from the power device flowing through the second resistor R2, the third resistor R3 and the fourth resistor R4, and the voltage drop of the third resistor R3 and the fourth resistor R4 provides a control electrode voltage for the first transistor T1. When the current flowing through the switch tube Q1 is too large, the potential of the first node N1 is raised, so that the voltage division of the third resistor R3 and the fourth resistor R4 is raised, and the potential of the control electrode of the first transistor T1 is raised, causing the first transistor T1 to be turned on, so that the control electrode of the switch tube Q1 is pulled down, and the switch tube Q1 is turned off due to cutoff, thereby realizing overcurrent protection. The process from the first current sampling circuit 12 to the trigger circuit 13 triggering to controlling the switch tube Q1 to turn off is a hardware circuit switching process, which realizes nanosecond protection of the power supply system.

[0068] It should be noted that the resistance of the above resistors is set according to the sampling multiple of the first current sensor TA1 and the overcurrent threshold of the power supply circuit 11, and the values ​​of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are set in coordination with each other.

[0069] Considering that the sampling current sampled by the first current sensor TA1 to the sensing output end is much smaller than the current flowing through the switch tube Q1, when the current flowing through the switch tube Q1 has exceeded the load capacity of the device but the sampling current at the output end has only a slight change, the voltage across the first resistor R1 as the sampling resistor is very small. When the voltage drop of the third resistor R3 and the fourth resistor R4 is not enough to reach the conduction voltage drop of the first transistor T1, the switch tube Q1 cannot be turned off, that is, the eddy current overcurrent that actually causes substantial damage to the power supply circuit 11 cannot be effectively protected, so that the devices in the power supply system are at risk of damage due to overcurrent protection.

[0070] In particular, in the embodiment of the present disclosure, the trigger circuit 13 is also electrically connected to the output end of the drive circuit 15, so that the drive circuit 15 is used to provide a bias for the trigger circuit, so that the trigger circuit 13 can turn off the switch tube Q1 based on the detected current even if a very small overcurrent occurs in the power supply circuit 11.

[0071] Specifically, refer to Figure 2 As shown, the trigger circuit 13 also includes: a fifth resistor R5 and a sixth resistor R6 connected in series, the first end of the fifth resistor R5 is electrically connected to the first output end of the drive circuit 15, and the second end of the sixth resistor R6 is electrically connected to the first end of the fourth resistor R4.

[0072] Figure 3FIG. 1 shows an equivalent circuit diagram of the trigger circuit 13 of the embodiment of the present disclosure. Figure 3 As shown, the voltage source V1 indicates that the voltage output by the driving circuit 15 is V1, and the voltage source V R1 Represents the voltage drop V of the sampled current on the first resistor R1 R1 (Right now, Figure 2 ), assuming that the current flowing through the fifth resistor R5 and the sixth resistor R6 from the voltage source V1 is I1; and assuming that the voltage source V R1 The current provided on the second resistor R2, the third resistor R3 and the fourth resistor R4 is I2, and the first transistor T1 is a triode. Then: V R4 =(I1+I2)×R4, at the same time, the base voltage of the first transistor T1 is: V B =I2×R3+V R4 =I2×R3+(I1+I2)×R4=I2×(R3+R4)+I1×R4.

[0073] It can be seen that the driving circuit 15 is equivalent to providing a bias for the base of the first transistor T1, and the current I1 is the bias current. The bias current generated by the driving circuit 15 generates a voltage drop on the fifth resistor R5 and the sixth resistor R6 to increase the bias voltage for the base of the first transistor T1, that is, the driving circuit 15 provides a driving voltage for the first transistor T1. By increasing the bias voltage, when the current flowing through the switch tube Q1 has generated an overcurrent, but due to the sensing multiple of the first current sensor TA1, the value of the voltage source VR1 is very small and insufficient to turn on the first transistor T1, the bias voltage can be used to turn on the first transistor T1, thereby turning off the switch tube Q1 to produce an effective overcurrent protection effect. In other words, the bias generated by the driving circuit 15 in the trigger circuit 13 improves the overcurrent protection sensitivity of the power supply overcurrent protection circuit.

[0074] On the other hand, under the same value of the voltage source VR1 , by increasing the bias, the value of the first resistor R1 can be further reduced, thereby reducing the power loss of the first current sampling circuit 12 .

[0075] It should be noted that the resistance values ​​of the above resistors are set according to the sampling multiple of the first current sensor TA1 and the overcurrent threshold of the power supply circuit 11, and the values ​​of the first resistor R1 to the sixth resistor R6 are set in coordination with each other.

[0076] In the embodiment of the present disclosure, the driving circuit 15 is used as a bias source, and the driving circuit 15 can be a pulse generator, but it is not limited thereto. In a specific implementation, it can be other signal sources that can provide bias. When implemented as a pulse generator, the pulse generator can be an independent pulse generator circuit or device, or a circuit structure integrated in an integrated circuit such as an MCU or an FPGA, which is not specifically limited herein.

[0077] Alternatively, in an embodiment of the present disclosure, the driving circuit 15 is controlled by the control unit 16 , that is, the driving circuit 15 can provide a pulse signal or stop providing a pulse signal under the control of the control unit 16 .

[0078] Optionally, refer to Figure 2 As shown, the trigger circuit 13 also includes: a first voltage suppression diode V2 and a second voltage suppression diode V3. The first electrode of the first voltage suppression diode V2 is electrically connected to the second end of the fifth resistor R5, and the second electrode is electrically connected to the negative electrode COM of the power supply V7. The first electrode of the second voltage suppression diode V2 is electrically connected to the control electrode of the switch tube Q1, and the second electrode is electrically connected to the negative electrode COM of the power supply V7.

[0079] Through this configuration, the first voltage suppression diode V2 can be used to protect the first transistor T1, and the second voltage suppression diode V3 can be used to protect the switch tube Q1.

[0080] It should be noted that although Figure 2 The first voltage suppression diode V2 and the second voltage suppression diode V3 are shown as bipolar transient voltage suppression diodes, but this is not intended to be limiting. In some application scenarios, unipolar transient voltage suppression diodes or other types of voltage suppression diodes may also be used, which are not described in detail herein.

[0081] Optionally, continue to refer to Figure 2 As shown, the trigger circuit 13 further includes: a third diode V4, and a seventh resistor R7 and an eighth resistor R8 connected in series.

[0082] Specifically, the first end of the seventh resistor R7 is electrically connected to the first output end of the driving circuit 15, the connection end of the seventh resistor R7 and the eighth resistor R8 is electrically connected to the first electrode of the first transistor T1, the second electrode of the eighth resistor R8 is electrically connected to the control electrode of the switch tube Q1, and the positive electrode of the third diode V4 is electrically connected to the second electrode of the first transistor T1, and the negative electrode is electrically connected to the negative electrode COM of the load V7.

[0083] Through this configuration, the unidirectional conduction effect of the third diode V4 can be utilized to protect the second electrode of the first transistor T1. When the protection is triggered, the first transistor T1 is in the on state, and the seventh resistor R7 plays a role in current limiting protection. At the same time, the eighth resistor R8 forms a current diversion effect on the control electrode of the switch tube Q1 to prevent oscillation during the transmission of the driving signal.

[0084] Continue to combine Figure 1 and Figure 2 As shown, the second current detection circuit 14 of the power supply overcurrent protection circuit includes a second current sensor TA2 connected in series between the switch tube Q1 and the negative electrode COM of the power supply V7, which is configured to detect the current of the power supply circuit 11 and transmit it to the control unit 16. The control unit 16 is configured to control the drive circuit 15 to stop output based on the received current.

[0085] Specifically, refer to Figure 2 As shown, the second current detection circuit 14 also includes: a ninth resistor R9, a tenth resistor R10 and an eleventh resistor R11. The first input terminal of the second current sensor TA2 is electrically connected to the second pole of the switch tube Q1, and the second input terminal is electrically connected to the negative pole COM of the power supply V7. Both ends of the ninth resistor R9 are electrically connected to the first sensing output terminal and the second sensing output terminal of the second current sensor TA1, as a sampling resistor. The first end of the tenth resistor R10 is electrically connected to the first sensing output terminal of the second current sensor TA2, the second end is electrically connected to the first end of the eleventh resistor R11 and electrically connected to the first end of the control unit 16, and the second end of the eleventh resistor R11 is electrically connected to the second end of the control unit 16 to detect the current of the power supply circuit 11.

[0086] Through the above settings, when the switch tube Q1 is working, the first current sensor TA2 detects the loop in the power supply loop 11, and the sensed current is sampled by the ninth resistor R9 serving as a sampling resistor and is reflected as a voltage signal across the ninth resistor R9. The voltage across the eleventh resistor R11 is transmitted to the control unit 16 as a sampling signal of the second current detection circuit 14 through the voltage divider of the tenth resistor R10 and the eleventh resistor R11.

[0087] Optionally, refer to Figure 2 As shown, a current processing circuit 17 may be provided between the second current detection circuit 14 and the control unit 16. The signal detected by the second current detection circuit 14 is processed by the current processing circuit 17 and then transmitted to the control unit 16. The current processing circuit 17 may be, for example, an analog-to-digital converter.

[0088] Of course, those skilled in the art should understand that the current processing circuit 17 is not necessary, and it can also be used as a circuit module in the control unit 16, or when the control unit 16 is an integrated circuit such as MCU or FPGA, the current processing circuit 17 can be integrated into the control unit 16, which is not elaborated in this article.

[0089] The control unit 16 may be a control system composed of an MCU, FPGA, DSP or other control chips. The control unit 16 receives the signal output by the second current detection circuit 14, compares the acquired signal with a pre-stored preset threshold, and cuts off the pulse signal of the drive circuit 15 if the preset threshold is exceeded.

[0090] For example, refer to Figure 2 As shown, the control unit 16 may include a judgment unit 116 and a processing unit 126. The judgment unit 116 compares the acquired signal with a preset threshold. If it is judged that the signal exceeds the preset threshold, an instruction is output to the processing unit 126. The processing unit 126 sends a control signal to the drive circuit 15 based on the received instruction, thereby controlling the drive circuit 15 to stop output.

[0091] Optionally, refer to Figure 2 As shown, when the control unit 16 determines that the received signal exceeds a preset threshold, it sends a control signal to the pulse power supply in the power supply circuit 11 to cut off the power supply V7 of the pulse power supply system.

[0092] By setting the second current detection circuit 14 and the control unit 16 to form a software protection circuit, it is possible to solve the problem that after the first transistor T1 of the pure hardware circuit turns off the switch tube Q1, the loop current flowing through the switch tube Q1 is zero, and the sampling current sensed by the first current detection circuit 12 no longer has the conduction condition to turn on the first transistor T1, and the overcurrent protection cannot be maintained, thereby causing repeated startup. In other words, by setting up a dual protection circuit of software and hardware, the switch tube Q1 can be turned off accurately and quickly at a speed of nanoseconds when an overcurrent occurs. At the same time, by using the software detection and protection mechanism, after judging the result of the overcurrent, the drive circuit that provides bias for the first transistor T1 stops outputting and maintains the protection action, thereby providing overcurrent protection in a timely, accurate, stable and effective manner, timely avoiding large currents from damaging other components of the system, and playing the role of protecting the circuit.

[0093] It is also worth mentioning that, considering that the software circuit can usually only accept and process smaller currents and voltages, in order to avoid the impact of overcurrent on the software circuit, in the embodiment of the present disclosure, the second current detection circuit 14 is set at the low end of the switch tube Q1, thereby providing good protection for the software side.

[0094] Reference Figure 4 As shown in the figure, Figure 2 The simulation diagram based on the circuit structure shown. The horizontal axis represents time, the curve represented by the small square connection line is the output waveform of the driving circuit 15, the curve represented by the circular connection line is the current of the power supply loop 11, and the curve represented by the triangle connection line is the current of the fourth transistor T1. It can be seen that on the basis of the driving bias provided by the driving circuit 15, a sudden overcurrent occurred in the power supply loop 11 at the moment of 4.004ms. At the moment of the overcurrent, the current of the first transistor T1 reached the peak value and turned on. Under the control of the hardware circuit, at the moment of 4.0055ms, the first transistor T1 was turned off, that is, the switch tube Q1 was turned off, resulting in the signal sampled by the first current detection circuit 12 being insufficient to turn on the first transistor T1, and the protection reaction time of the hardware circuit was in the nanosecond level. At the same time, under the action of software protection, after the loop circuit 11 fell back, the power protection circuit did not repeatedly turn on the first transistor T1 but remained in a state where both the loop 11 and the first transistor T1 were cut off.

[0095] It can be seen that by utilizing the coordination of the hardware and software of the embodiment of the present disclosure, the power supply circuit can be accurately and quickly protected from overcurrent damage, while avoiding the disadvantage that a pure hardware circuit cannot maintain an overcurrent fault and repeatedly starts up.

[0096] Considering that in the power supply system, if the voltage in the power supply circuit 11 is too high and the voltage resistance of a single power device IGBT cannot withstand the high voltage, it is often necessary to connect multiple power devices in series to meet the voltage resistance requirement. In this case, if only one power device is cut off for protection, the excessive voltage suspension at other locations will also cause permanent damage to the circuit devices. In other words, the overcurrent protection of one power device is not sufficient to protect the power supply circuit.

[0097] Therefore, in some other optional embodiments, referring to Figure 5 As shown, the power protection circuit includes: a power supply circuit 11, N first current sampling circuits 12_1, 12_2, ..., 12_N and N trigger circuits 13_1, 13_2, ..., 13_N arranged in a one-to-one correspondence, a second current sampling circuit 14, a driving circuit 15, and a control unit 16, where N is an integer greater than 1.

[0098] At this time, the power supply circuit 11 includes a power supply V7, N switch tubes Q1, Q2, ..., QN and a load RL connected in series in sequence. The switch tubes Q1, Q2, ..., QN, the first current sampling circuits 12_1, 12_2, ..., 12_N and the trigger circuits 13_1, 13_2, ..., 13_N are arranged in a one-to-one correspondence.

[0099] That is to say, a first current sensor is connected in series to the high end of each switch tube, and thus a first current detection circuit 12 and a trigger circuit 13 are correspondingly provided. The circuit architecture and working mechanism of each first current detection circuit 12 and trigger circuit 13 are consistent with those described in the above embodiments and will not be repeated here. When an overcurrent occurs in the power supply circuit 11, each first current detection circuit 12 detects the current and simultaneously turns off the corresponding switch tube Q through the trigger circuit 13.

[0100] In particular, in order to ensure that the protection of each switch tube Q is independently controlled, refer to Figure 5 As shown, the power overcurrent protection circuit further includes an isolation transformer TX1, and the isolation transformer TX1 is arranged between the driving circuit 15 and the trigger circuits 13_1, 13_2, ..., 13_N.

[0101] Specifically, the isolation transformer TX1 includes a group of primary coils electrically connected to the output end of the driving circuit 15 and multiple groups of secondary coils arranged in one-to-one correspondence with the N trigger circuits 13_1, 13_2, ..., 13_N, and the first pole of each group of secondary coils is electrically connected to the corresponding trigger circuit 13, and the second pole is electrically connected to the negative pole COM of the power supply V7. Those skilled in the art should understand that each secondary coil is electrically isolated.

[0102] Through the above configuration, one driving circuit 15 can be used to independently control the on and off of multiple switch tubes Q1 by multiple trigger circuits 13_1 , 13_2 , . . . , 13_N.

[0103] It is also worth mentioning that since the purpose of the software circuit is to maintain the overcurrent protection state of the hardware circuit, when multiple switch tubes Q are included, it is only necessary to connect a second current sensor in series between one end of the multiple switch tubes Q connected in series close to the negative electrode COM of the power supply V7 and the negative electrode COM, and feed back the sampled current to the control unit 16 and control the output state of the drive circuit 15 based on the judgment and processing results.

[0104] Based on the same inventive concept, an embodiment of the present disclosure further provides an electronic device, including the power supply overcurrent protection circuit described above. Among them, the power supply circuit of the power supply protection circuit includes a power device called a switch tube Q or V7 as a high voltage and high current power supply, which can be a converter circuit of various structures including a high power pulse power supply, and the electronic device can be any device or component including the above power supply overcurrent protection circuit, which is not limited in this embodiment.

[0105] Obviously, the above embodiments of the present disclosure are merely examples for clearly illustrating the present disclosure, and are not limitations on the implementation methods of the present disclosure. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present disclosure are still within the protection scope of the present disclosure.

Claims

1. A power supply overcurrent protection circuit, characterized in that: include: a power supply circuit, at least one first current sampling circuit and at least one trigger circuit arranged in one-to-one correspondence, a second current sampling circuit, a drive circuit, and a control unit, The power supply circuit includes: a power supply, at least one switch tube and a load connected in series in sequence, wherein the switch tube, the first current sampling circuit and the trigger circuit are arranged in a one-to-one correspondence. The first current detection circuit comprises a first current sensor connected in series between the load and the corresponding switch tube, and configured to detect the current of the power supply circuit; The trigger circuit is electrically connected to a first node corresponding to a first sensing output terminal of the first current sensor, a negative electrode of the power supply, and an output terminal of the driving circuit, and is configured to turn off the corresponding switch tube based on the detected current; The second current detection circuit includes a second current sensor connected in series between at least one switch tube connected in series and the negative electrode, configured to detect the current of the power supply circuit and transmit it to the control unit, The control unit is configured to control the drive circuit to stop output based on the received detection signal.

2. The power overcurrent protection circuit according to claim 1, characterized in that: The first current detection circuit further includes: a first resistor, wherein: The first input terminal of the first current sensor is electrically connected to the load, the second input terminal is electrically connected to the first pole of the corresponding switch tube, the first sensing output terminal is electrically connected to the first end of the first resistor, and the second sensing output terminal is electrically connected to the second end of the first resistor and electrically connected to the negative pole of the power supply.

3. The power overcurrent protection circuit according to claim 1, characterized in that: The trigger circuit comprises: a first transistor, a second resistor, a third resistor and a fourth resistor, The first electrode of the first transistor is electrically connected to the control electrode of the corresponding switch tube, the second electrode is electrically connected to the negative electrode of the power supply, and the control electrode is electrically connected to the first end of the third resistor. The first end of the second resistor is electrically connected to the first node, the second end is electrically connected to the first end of the third resistor, the second end of the third resistor is electrically connected to the first end of the fourth resistor, and the second end of the fourth resistor is electrically connected to the negative electrode of the power supply.

4. The power overcurrent protection circuit according to claim 3, characterized in that: The trigger circuit further includes: a fifth resistor and a sixth resistor connected in series, A first end of the fifth resistor is electrically connected to a first output end of the driving circuit, and a second end of the sixth resistor is electrically connected to a first end of the fourth resistor.

5. The overcurrent protection circuit according to claim 4, characterized in that: The trigger circuit further includes: a first voltage suppression diode and a second voltage suppression diode. The first electrode of the first voltage suppression diode is electrically connected to the second end of the fifth resistor, and the second electrode is electrically connected to the negative electrode of the power supply. A first electrode of the second voltage suppression diode is electrically connected to a control electrode of the corresponding switch tube, and a second electrode is electrically connected to a negative electrode of the power supply.

6. The power overcurrent protection circuit according to claim 3, characterized in that: The trigger circuit further includes: a third diode, and a seventh resistor and an eighth resistor connected in series, The first end of the seventh resistor is electrically connected to the first output end of the driving circuit, the connection end of the seventh resistor and the eighth resistor is electrically connected to the first electrode of the first transistor, and the second end of the eighth resistor is electrically connected to the control electrode of the corresponding switch tube. The anode of the third diode is electrically connected to the second electrode of the first transistor, and the cathode of the third diode is electrically connected to the cathode of the load.

7. The power overcurrent protection circuit according to claim 1, characterized in that: The second current detection circuit further includes: a ninth resistor, a tenth resistor and an eleventh resistor, The first input terminal of the second current sensor is electrically connected to the second electrode of the switch tube close to the negative electrode of the power supply in the at least one switch tube connected in series, and the second input terminal is electrically connected to the negative electrode of the power supply. The two ends of the ninth resistor are electrically connected to the first sensing output terminal and the second sensing output terminal of the second current sensor. The first end of the tenth resistor is electrically connected to the first sensing output end of the second current sensor, the second end is electrically connected to the first end of the eleventh resistor and electrically connected to the first end of the control unit, and the second end of the eleventh resistor is electrically connected to the second end of the control unit to detect the current of the power supply circuit.

8. The power overcurrent protection circuit according to claim 7, characterized in that: The control unit acquires the current of the power supply circuit based on the signals received at the first end and the second end, and controls the drive circuit to stop outputting when it is determined that the acquired current is greater than a preset threshold.

9. The power overcurrent protection circuit according to claim 1, characterized in that: The first current detection circuit, the trigger circuit, and the switch tube are all multiple, The power supply overcurrent protection circuit further includes an isolation transformer, which is arranged between the drive circuit and the trigger circuit. The isolation transformer includes a group of primary coils electrically connected to the output end of the drive circuit and multiple groups of secondary coils arranged in a one-to-one correspondence with the multiple trigger circuits. The first pole of each group of secondary coils is electrically connected to the corresponding trigger circuit, and the second pole is electrically connected to the negative pole of the power supply.

10. An electronic device, characterized in that: The invention comprises a power supply overcurrent protection circuit as claimed in any one of claims 1 to 9.

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