Power supply overcurrent protection circuit and electronic equipment

Abstract

The utility model 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, in particular to a power supply overcurrent protection circuit and an electronic device. BACKGROUND

[0002] At present, in the high-voltage high-power pulse power supply, in the case of high-voltage fast short circuit, tens of thousands of amperes of instantaneous current will be generated, which is easy to cause damage to other devices in the system, so a reliable overcurrent protection circuit is crucial to the stable and reliable operation of the system.

[0003] At present, there are two ideas of drive protection and overcurrent protection to achieve the purpose of protection after overcurrent.

[0004] The common drive protection scheme is to detect the voltage across the drive 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 easy to cause 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 the current, and then use a signal processor MCU to judge whether the current signal exceeds the threshold. When it is judged that the current signal exceeds the protection threshold, the corresponding protection signal is output or the protection action is taken. However, in the case of large current, the sampling resistor will generate a lot of power loss, reducing the system output efficiency; and the current processing of the signal processor has a certain delay, which is easy to cause the protection to be not timely, causing the power device to age prematurely, and even be damaged.

[0006] Therefore, a scheme is needed that can effectively and timely protect the overcurrent of the power supply. CONTENT 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, comprising: a power supply circuit, at least one first current sampling circuit and at least one trigger circuit corresponding one by one, a second current sampling circuit, a drive circuit, a control unit,

[0008] The power supply circuit comprises: a power supply, at least one switch tube and a load connected in series,

[0009] The first current detection circuit comprises 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 circuit;

[0010] The trigger circuit is electrically connected to the 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 drive circuit, and is configured to turn off the corresponding switch tube based on the detected current;

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

[0012] a control unit configured to control the driving circuit to stop outputting based on the received detection signal.

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

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

[0015] Optionally, the trigger circuit comprises 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 comprises a fifth resistor and a sixth resistor connected in series,

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

[0020] Optionally, the trigger circuit further comprises a first voltage suppression diode and 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] The first electrode of the second voltage suppression diode is electrically connected to the control electrode of the corresponding switch tube, and the second electrode is electrically connected to the negative electrode of the power supply.

[0023] Optionally, the trigger circuit further comprises 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 positive electrode of the third diode is electrically connected to the second electrode of the first transistor, and the negative electrode is electrically connected to the negative electrode of the load.

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

[0027] The first input end 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 end is electrically connected to the negative electrode of the power supply,

[0028] The two ends of the ninth resistor are electrically connected between the first sensing output end and the second sensing output end 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, so as to detect the current of the power supply loop.

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

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

[0032] The power supply overcurrent protection circuit further comprises an isolation transformer, which is arranged between the driving circuit and the trigger circuit,

[0033] The isolation transformer comprises a primary coil electrically connected to the output end of the driving circuit and a plurality of secondary coils arranged one-to-one corresponding to the plurality of trigger circuits, and 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 electrode of the power supply.

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

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

[0036] The present disclosure aims at the existing problems, and formulates a power supply overcurrent protection circuit and an electronic device. The first current sensor connected in series in the power supply loop senses the current of the power supply loop, and the trigger circuit controls the switch tube to be turned off 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, so as to realize double overcurrent protection of hardware and software, avoid the problem that pure hardware circuit cannot keep overcurrent fault repeated starting, realize low-power overcurrent protection, and has wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present disclosure, and for those skilled in the art, other drawings can also be obtained from these drawings without creative effort.

[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 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 a simulation diagram of the power supply overcurrent protection circuit is shown; Figure 2

[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 technical solutions in the embodiments of the present disclosure, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present disclosure, and for those skilled in the art, other drawings can also be obtained from these drawings without creative effort.

[0044] It should be noted that, unless otherwise defined, technical terms or scientific terms used in the present disclosure should be understood as their common meanings to those skilled in the art to which the present disclosure pertains. The terms “first”, “second” and similar terms used in the present disclosure do not represent any order, number or importance, but are only used to distinguish different components. Similarly, the terms “one”, “a” or “the” and similar terms do not represent a quantity limitation, but represent the existence of at least one. The terms “include” or “contain” and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms “connect” or “connected” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0045] ​In the present disclosure, "electrically connected" includes a case where components are connected together through an element having some electrical effect. The element having some electrical effect is not particularly limited as long as it can perform transmission and reception of an electrical signal between the connected components. Examples of the element having some electrical effect include not only electrodes and wiring but also switching elements such as transistors, resistors, inductors, capacitors, other elements having various functions, and the like.

[0046] As used in the present disclosure, "parallel", "perpendicular", and "equal" include the stated case and a case similar to the stated case within an acceptable deviation range, which is determined by a person of ordinary skill in the art taking into account the measurement being discussed and the error related to the measurement of a specific quantity (i.e., the limitation of the measurement system). For example, "equal" includes absolute equality and approximate equality, where the acceptable deviation range of approximate equality may, for example, be a difference between the two that is less than or equal to 5% of either.

[0047] Referring to Figure 1 As shown in the figure, the present disclosure provides a power supply overcurrent protection circuit, comprising: a power supply loop 11, at least one first current detection circuit 12 and at least one trigger circuit 13 which are one-to-one correspondingly arranged, a second current detection circuit 14, a driving circuit 15, a control unit 16,

[0048] The power supply loop 11 comprises: a power supply, at least one switching tube Q and a load RL which are connected in series, and the switching tube Q, the first current sampling circuit 12 and the trigger circuit 13 are one-to-one correspondingly arranged,

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

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

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

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

[0053] In the embodiment, the current of the power supply circuit is sensed by the first current sensor connected in series in the power supply circuit, and the switch tube is turned off quickly by the trigger circuit based on the current, while the second current sensor detects the power supply current and transmits it to the control unit for software processing, so as to realize double overcurrent protection of hardware and software, avoid the problem that pure hardware circuit cannot keep overcurrent fault repeated start, and realize low-power, fast and effective overcurrent protection.

[0054] The embodiments of the present disclosure will be described in detail below with reference to Figures 1 to 4 The embodiments of the present disclosure are described in detail in combination with specific examples.

[0055] In one specific example, in combination with Figure 1 and Figure 2 As shown in the figures, 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 driving circuit 15 and a control unit 16.

[0056] The power supply circuit 11 includes, for example, a power supply V7, a switch tube Q1 and a load RL connected in series. In the embodiment of the present disclosure, the switch tube Q1 is a power semiconductor device IGBT, and in actual application, the switch tube Q1 can also be a MOS tube without considering the power switching capability. In addition, the conduction type of the switch tube Q1 is N type. For example, the power supply V7 can be a high-voltage 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 for controlling the power supply path of the power supply V7 to the load RL. In addition, for example, the power supply V7 and the switch tube Q1 can jointly constitute a high-voltage high-power pulse power supply to supply power to the load RL, at this time, the power supply V7 refers to the power supply source 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 constitutions are all within the protection of the power supply circuit 11 of the present disclosure.

[0057] It should be noted that when the number of switch tubes does not need to be distinguished, they are collectively referred to as switch tube Q, and when they need to be distinguished, one switch tube is referred to as switch tube Q1.

[0058] Continuing 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 loop 11, which is also the current flowing through the switch tube Q1. 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 the current flowing through the power supply loop 11 by electromagnetic mutual inductance and sense a certain proportion of the current at the sensing output end. By this arrangement, the power loss is small when sensing the large current of up to kiloampere in the power supply loop 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 1:100 in this example, but it is not intended to be limited, and it can be set as needed 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, connecting the first current sensor TA1 in series at the high end of the power device, the excessively high current can be accurately sensed, and the overcurrent can be quickly sensed and the switch tube Q1 can be turned off at the moment when the large current flows, thereby improving the current detection accuracy and protecting the pulse power supply system.

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

[0061] Specifically, the first input end of the first current sensor TA1 is electrically connected to the load RL, the second input end is electrically connected to the first pole of the switch tube Q1, the first sensing output end is electrically connected to the first end of the first resistor R1, and the second sensing output end is electrically connected to the second end of the first resistor R1 and to the negative pole of the power supply V7. In this example, the sensing current of 1 / 100 of the current flowing through the switch tube Q1 in the power supply loop 11 flows through the first resistor R1 and is embodied as the 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 end COM, which can be the ground end in actual implementation. Hereinafter, for the convenience of understanding and description, the negative pole of the power supply V7 is referred to as the label "COM".

[0062] It should be noted that, Figure 2 The equivalent circuit of the power supply V7 is only an exemplary equivalent way, in other words, if the power supply V7 supplies power to the load RL as a power supply, the negative pole of the load RL can also be electrically connected to the common end, which is not described herein.

[0063] Continuing 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 of the first current sensor TA1, the negative COM of the power supply V7, and the output of the driving circuit 15, and is configured to turn off the switch tube Q1 based on the detected current.

[0064] Specifically, referring 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 first transistor T1 is of N-type. The first pole 3 of the first transistor T1 is electrically connected to the control pole of the corresponding switch tube Q1, the second pole 2 is electrically connected to the negative COM of the power supply V7, and the control pole 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 pole 3 is the collector, the second pole 2 is the emitter, and the control pole 1 is the base, but the present disclosure is not intended to be limited thereto, and other transistors capable of controlling conduction based on the potential of the control pole are also within the protection scope of the present disclosure.

[0066] Further, the first pole 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 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 COM of the power supply V7, and the total voltage drop of the series-connected second resistor R2, third resistor R3, and fourth resistor R4 is the voltage drop across the first resistor R1 as the sampling resistor. The voltage division of the third resistor R3 and the fourth resistor R4 is provided to the control pole 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 works, the current flowing through the switch tube Q1 is collected by the first current sensor TA1, the first resistor R1 converts the collected current by 1:100 into a voltage signal, the first resistor R1 is connected in series and parallel with the second resistor R2, the third resistor R3 and the fourth resistor R4, which is equivalent to that a small current sampled from the power device flows 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 the control electrode voltage of the first transistor T1. When the current flowing through the switch tube Q1 is too large, the potential of the first node N1 rises, thereby the voltage division of the third resistor R3 and the fourth resistor R4 rises, and the potential of the control electrode of the first transistor T1 rises, which causes the first transistor T1 to be turned on, thereby the control electrode of the switch tube Q1 is pulled down, the switch tube Q1 is turned off due to the cut-off, and the overcurrent protection is realized. The process from the first current sampling circuit 12 to the trigger circuit 13 triggering to the control switch tube Q1 to be turned off is a hardware circuit switching process, which realizes the nanosecond-level protection of the power supply system.

[0068] 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, the second resistor R2, the third resistor R3 and the fourth resistor R4 are set in cooperation with each other.

[0069] It is considered that the sampling current of the first current sensor TA1 sampled 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 only has a slight change, the voltage across the first resistor R1 as a sampling resistor is very small, and the voltage drop of the third resistor R3 and the fourth resistor R4 is not enough to reach the turn-on voltage drop of the first transistor T1, so that the switch tube Q1 cannot be turned off, that is, the eddy current overcurrent which substantially damages the power supply circuit 11 cannot be effectively protected, and thus the devices in the power supply system have the risk of damage caused by overcurrent protection.

[0070] In particular, in the embodiment of the present disclosure, the trigger circuit 13 is electrically connected to the output end of the driving circuit 15 at the same time, so that the driving circuit 15 provides bias for the trigger circuit, and the trigger circuit 13 can turn off the switch tube Q1 based on the detected current even if a slight overcurrent occurs in the power supply circuit 11.

[0071] Specifically, referring to FIG. 1, Figure 2 As shown in FIG. 1, the trigger circuit 13 further comprises a fifth resistor R5 and a sixth resistor R6 connected in series, a first end of the fifth resistor R5 is electrically connected to the first output end of the driving circuit 15, and a second end of the sixth resistor R6 is electrically connected to the first end of the fourth resistor R4.

[0072] Figure 3An equivalent circuit diagram of the trigger circuit 13 of the embodiment of the present disclosure is shown. Referring to Figure 3 indicated, where voltage source V1 represents the voltage output by the driving circuit 15 as V1, voltage source V R1 represents the voltage drop V R1 (i.e. Figure 2 the potential of the first node N1 in the middle), it is assumed that the current flowing through the fifth resistor R5 and the sixth resistor R6 of the voltage source V1 is I1; and it is assumed that the current provided on the second resistor R2, the third resistor R3 and the fourth resistor R4 of the voltage source V R1 is I2, and the first transistor T1 is a triode. Then, V R4 = (I1+I2) x R4, and the base voltage of the first transistor T1 is: B = I2 x R3 + V R4 = I2 x R3 + (I1+I2) x R4 = I2 x (R3+R4) + I1 x R4.

[0073] It can be seen that the driving circuit 15 provides a bias for the base of the first transistor T1, the current I1 is the bias current, and the bias voltage is added to the base of the first transistor T1 by the voltage drop generated on the fifth resistor R5 and the sixth resistor R6 by the bias current generated by the driving circuit 15, that is, the driving voltage is provided for the first transistor T1 by the driving circuit 15. By increasing the bias voltage, the first transistor T1 is turned on by the bias voltage when the current flowing through the switch tube Q1 has already generated an overcurrent, but the value of the voltage source VR1 is small due to the sensing multiple of the first current sensor TA1 and is insufficient to turn on the first transistor T1, thereby turning off the switch tube Q1 to generate an effective overcurrent protection effect. That is, the bias generated in the trigger circuit 13 by the driving circuit 15 improves the overcurrent protection sensitivity of the power 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, 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 cooperation with each other.

[0076] In the embodiments of the present disclosure, the driving circuit 15 serves as a bias supply source, which can be a pulse generator, but is not limited thereto, and can be other signal source capable of providing bias in specific implementation. When implemented as a pulse generator, the pulse generator can be a separate 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 the embodiments 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, referring to Figure 2 As shown in the figure, the trigger circuit 13 further 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 pole 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 pole COM of the power supply V7.

[0079] Through the above arrangement, the first transistor T1 can be protected by the first voltage suppression diode V2, and the switch tube Q1 can be protected by the second voltage suppression diode V3.

[0080] It should be noted that although Figure 2 Although the first voltage suppression diode V2 and the second voltage suppression diode V3 are shown as bipolar transient voltage suppression diodes in the figure, it is not intended to be limited thereto, and in some application scenarios, unipolar transient voltage suppression diodes or other types of voltage suppression diodes can also be used, which will not be described herein.

[0081] Optionally, continuing to refer to Figure 2 As shown in the figure, 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, the anode of the third diode V4 is electrically connected to the second electrode of the first transistor T1, and the cathode is electrically connected to the negative pole COM of the load V7.

[0083] With this setup, the unidirectional conduction of the third diode V4 can be used to protect the second terminal of the first transistor T1. When the protection is triggered, the first transistor T1 is in the conducting state, the seventh resistor R7 plays the role of current limiting protection, and at the same time, the eighth resistor R8 forms a current-driving effect on the control terminal of the switching transistor Q1 to prevent oscillation during the transmission of the drive 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 switching transistor Q1 and the negative terminal COM of the power supply V7, configured to detect the current in 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 further 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 terminal of the switching transistor Q1, and the second input terminal is electrically connected to the negative terminal COM of the power supply V7. The two ends of the ninth resistor R9 are electrically connected to the first and second sensing output terminals of the second current sensor TA1, serving 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 terminal of the control unit 16, and the second end of the eleventh resistor R11 is electrically connected to the second terminal of the control unit 16 to detect the current in the power supply circuit 11.

[0086] With the above settings, when the switching transistor Q1 is working, the first current sensor TA2 detects the circuit in the power supply circuit 11. The sensed current is sampled by the ninth resistor R9, which is used as a sampling resistor, and is reflected as a voltage signal across the ninth resistor R9. Through the voltage division of the tenth resistor R10 and the eleventh resistor R11, 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.

[0087] Optionally, refer to Figure 2 As shown, a current processing circuit 17 can also 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 can 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, it can also be 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 in the control unit 16, which will not be described here.

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

[0090] For example, referring to Figure 2 , the control unit 16 can include a judgment unit 116 and a processing unit 126, the judgment unit 116 compares the obtained signal with the preset threshold, and if it is judged that the preset threshold is exceeded, an instruction is output to the processing unit 126, and 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] Alternatively, referring to Figure 2 , when the control unit 16 judges that the received signal exceeds the preset threshold, a control signal is sent 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, the problem of repeated start caused by the fact 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 of turning on the first transistor T1, thereby causing the overcurrent protection to be unable to maintain, can be solved. In other words, by setting a software and hardware double protection circuit, the switch tube Q1 can be turned off at nanosecond level speed when overcurrent occurs, and at the same time, by using the software detection and protection mechanism, the result of overcurrent occurrence is judged, and the protection action is maintained by stopping the drive circuit for providing bias to the first transistor T1, thereby timely, accurately and stably and effectively providing overcurrent protection, avoiding damage to other devices in the system caused by large current, and playing a role in protecting the circuit.

[0093] In addition, it is worth mentioning that considering that software circuits can usually only accept and process small currents and voltages, in order to avoid the influence of overcurrent on software circuits, the second current detection circuit 14 in the embodiment of the disclosure is arranged at the low end of the switch tube Q1, thereby being able to provide good protection to the software side.

[0094] Referring to Figure 4 , the figure showsFigure 2 The simulation diagram based on the circuit structure is shown. The horizontal axis represents time, the curve represented by the connection of small squares is the output waveform of the driving circuit 15, the curve represented by the connection of circles is the current of the power supply circuit 11, and the curve represented by the connection of triangles 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, the power supply circuit 11 has a steep rising overcurrent at the time of 4.004 ms, at the moment of the occurrence of the overcurrent, the current of the first transistor T1 reaches the peak value and turns on, under the control of the hardware circuit, at the time of 4.0055 ms, the first transistor T1 has been turned off, that is, the switch tube Q1 has been turned off, and the signal sampled by the first current detection circuit 12 is insufficient to turn on the first transistor T1, and the protection reaction time of the hardware circuit is in the order of nanoseconds. At the same time, under the action of the software protection, after the fall of the loop circuit 11, the power supply protection circuit does not repeatedly turn on the first transistor T1, but remains in the state that the loop circuit 11 and the first transistor T1 are both cut off.

[0095] It can be seen that by using the cooperation of the hardware and the software of the embodiment of the present disclosure, the power supply circuit can be accurately and quickly protected from overcurrent damage, and the disadvantage of repeated start caused by the pure hardware circuit unable to maintain overcurrent failure is avoided.

[0096] It is considered that in the power supply system, if the voltage in the power supply circuit 11 is too high and the withstand voltage 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 withstand voltage requirement. In this case, if protection is performed by cutting off only one power device, the overvoltage at other positions also causes permanent damage to the circuit device, that is, the overcurrent protection of one power device is insufficient to protect the power supply circuit.

[0097] Therefore, in some other optional embodiments, with reference to Figure 5 As shown, the power supply 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 which are one-to-one correspondingly arranged, a second current sampling circuit 14, a driving circuit 15, and a control unit 16, and 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, and 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 one-to-one correspondingly arranged.

[0099] That is, the high end of each switch tube is in series with a first current sensor, thereby corresponding to be provided with a first current detection circuit 12 and a trigger circuit 13, the circuit architecture and working mechanism of each first current detection circuit 12 and trigger circuit 13 are consistent with the above embodiment, and will not be described here again. When overcurrent occurs in the power supply loop 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, referring to Figure 5 As shown, the power supply overcurrent protection circuit further includes an isolation transformer TX1, which 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 a plurality of groups of secondary coils corresponding to the N trigger circuits 13_1, 13_2, …, 13_N, 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 arrangement, one driving circuit 15 can be used to independently control the conduction and turn-off of the plurality of trigger circuits 13_1, 13_2, …, 13_N to the plurality of switch tubes Q1.

[0103] In addition, it is worth mentioning that since the purpose of the software circuit is to maintain the overcurrent protection state of the hardware circuit, when including a plurality of switch tubes Q, only a second current sensor needs to be connected in series between the end of the plurality of switch tubes Q close to the negative pole COM of the power supply V7 and the negative pole COM, and the sampled current is fed back to the control unit 16 and the output state of the driving circuit 15 is controlled based on the judgment and processing result.

[0104] Based on the same inventive concept, the embodiments of the present disclosure also provide an electronic device comprising the power supply overcurrent protection circuit described above. Wherein, the power supply or V7 as a high-voltage and high-current power supply comprising power devices called switch tubes Q in the power supply loop of the power supply protection circuit can be a variety of structures of transformer circuit including high-power pulse power supply, and the electronic device can be any device or component comprising the above-mentioned power supply overcurrent protection circuit, and the present embodiment is not limited.

[0105] Obviously, the above embodiments of the present disclosure are merely examples for clearly illustrating the present disclosure, and are not intended to limit the implementation manners of the present disclosure. Based on the above description, other different forms of changes or variations can be made by those skilled in the art, and it is impossible to enumerate all the implementation manners here. Any obvious changes or variations derived from the technical solutions of the present disclosure shall still fall within the protection scope of the present disclosure.

Claims

1. A power supply overcurrent protection circuit, characterized by, The application relates to a power supply circuit, at least one first current sampling circuit and at least one trigger circuit, a second current sampling circuit, a driving circuit and a control unit. The power supply circuit comprises a power supply, at least one switch tube and a load connected in series, and the switch tube, the first current sampling circuit and the trigger circuit are arranged one by one. The first current detection circuit comprises a first current sensor connected between the load and the corresponding switch tube, and is 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 end of the first current sensor, a negative electrode of the power supply and an output end of the driving circuit, and is configured to turn off the corresponding switch tube based on the detected current. The second current detection circuit comprises a second current sensor connected between the at least one switch tube and the negative electrode in series, and is configured to detect the current of the power supply circuit and transmit the current to the control unit. The control unit is configured to control the driving circuit to stop outputting based on the received detection signal. The first current detection circuit further comprises a first resistor.

2. The power supply overcurrent protection circuit of claim 1, wherein, The first input end of the first current sensor is electrically connected to the load, the second input end is electrically connected to the first electrode of the corresponding switch tube, the first sensing output end is electrically connected to the first end of the first resistor, and the second sensing output end is electrically connected to the second end of the first resistor and the negative electrode of the power supply. The trigger circuit comprises a first transistor, a second resistor, a third resistor and a fourth resistor.

3. The power supply overcurrent protection circuit of claim 1, wherein, 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. The trigger circuit further comprises a fifth resistor and a sixth resistor connected in series.

4. The power supply overcurrent protection circuit of claim 3, wherein, The first end of the fifth resistor is electrically connected to the first output end of the driving circuit, and the second end of the sixth resistor is electrically connected to the first end of the fourth resistor. The trigger circuit further comprises a first voltage suppression diode and a second voltage suppression diode.

5. The overcurrent protection circuit of claim 4, wherein, 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. The first electrode of the second voltage suppression diode is electrically connected to the control electrode of the corresponding switch tube, and the second electrode is electrically connected to the negative electrode of the power supply. The trigger circuit further comprises a third diode and a seventh resistor and an eighth resistor connected in series.

6. The power supply overcurrent protection circuit of claim 3, wherein, 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 positive electrode of the third diode is electrically connected to the second electrode of the first transistor, and the negative electrode is electrically connected to the negative electrode of the load.

7. The power supply overcurrent protection circuit of claim 1, wherein, The second current detection circuit further comprises a ninth resistor, a tenth resistor and an eleventh resistor, The first input end 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 among the at least one switch tube in series connection, and the second input end is electrically connected to the negative electrode of the power supply, The two ends of the ninth resistor are electrically connected between the first sensing output end and the second sensing output end 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, and 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, so as to detect the current of the power supply loop.

8. The power supply overcurrent protection circuit of claim 7, wherein, The control unit obtains the current of the power supply loop based on the signals received by the first end and the second end, and controls the driving circuit to stop outputting when it is determined that the obtained current is greater than a preset threshold.

9. The power supply overcurrent protection circuit of claim 1, wherein, The first current detection circuit, the trigger circuit and the switch tube are multiple, The power supply overcurrent protection circuit further comprises an isolation transformer, and the isolation transformer is arranged between the driving circuit and the trigger circuit, The isolation transformer comprises a group of primary coils electrically connected to the output end of the driving circuit and a plurality of groups of secondary coils corresponding to the plurality of trigger circuits, the first electrode of each group of secondary coils is electrically connected to the corresponding trigger circuit, and the second electrode is electrically connected to the negative electrode of the power supply.

10. An electronic device, comprising: The power supply overcurrent protection circuit comprises the power supply overcurrent protection circuit according to any one of claims 1-9. The power supply overcurrent protection circuit comprises the power supply overcurrent protection circuit according to any one of claims 1-9.

Images