Intrusive current measurement device

Abstract

The application belongs to the technical field of current measuring equipment, and particularly relates to an invasive current measuring device, which comprises an input sampling measuring module, a front-stage protection and sampling switch module and a rear-stage protection and sampling switch module. The input sampling measuring module comprises an input port, a sampling circuit, a signal output circuit, a first node and a second node. The front-stage protection and sampling switch module comprises a first-stage switch circuit, an input current monitoring circuit and a third node. The rear-stage protection and sampling switch module comprises a second-stage switch circuit. The application adopts single gear measurement and common input ports through the input sampling measuring module, the front-stage protection and sampling switch module and the rear-stage protection and sampling switch module, so as to effectively simplify the mechanical structure and the circuit structure of the multimeter. In addition, through the cooperation of the plurality of second-stage switch circuits and the sampling circuit, a plurality of ranges are flexibly realized, and a larger measurement range and higher resolution are further realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of current measurement, in particular to an invasive current measurement device. BACKGROUND

[0002] In the related art, when a multimeter is used to measure the current of a target, the current size needs to be estimated in advance, and then the input port and the range are manually selected. If the current value of the target to be measured is small and a large current measurement channel is selected, the reading is inaccurate due to small resolution, affecting the measurement accuracy. If the current value of the target to be measured is large and a small current measurement channel is selected, the fuse tube of the small current measurement channel will be directly burned out, causing the multimeter to be damaged, so the multimeter needs to be repaired, which is very troublesome.

[0003] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0004] In view of at least one of the above technical problems, the present application provides an invasive current measurement device, which solves the problem in the related art that when a multimeter is used to measure the current of a target, the current size needs to be estimated in advance, and then the input port and the range are manually selected. If the current value of the target to be measured is small and a large current measurement channel is selected, the reading is inaccurate due to small resolution, affecting the measurement accuracy. If the current value of the target to be measured is large and a small current measurement channel is selected, the fuse tube of the small current measurement channel will be directly burned out, causing the multimeter to be damaged, so the multimeter needs to be repaired, which is very troublesome.

[0005] The present application provides an invasive current measurement device, comprising:

[0006] The input sampling measurement module comprises an input port, a sampling circuit, a signal output circuit, a first node and a second node. The input port is connected to the first node. The first end of the sampling circuit and the first end of the signal output circuit are connected to the first node. The second end of the sampling circuit and the second end of the signal output circuit are connected to the second node. The sampling circuit further has a plurality of access points.

[0007] The front-stage protection and sampling switch module comprises a first-stage switch circuit, an input current monitoring circuit and a third node. The first end of the first-stage switch circuit is connected to the input port. The second end of the first-stage switch circuit and the first end of the input current monitoring circuit are connected to the third node. The second end of the input current monitoring circuit is connected to the third end of the first-stage switch circuit. The third node is connected to the second node.

[0008] The back-stage protection and sampling switch module comprises a first secondary switch circuit, a first end of the first secondary switch circuit is connected with the input port, and a second end of the first secondary switch circuit is connected with an access point of the sampling circuit, wherein I is an integer.

[0009] The application has the following technical effects: the application adopts single gear measurement and common input port through the input sampling measurement module, the front-stage protection and sampling switch module and the back-stage protection and sampling switch module, effectively simplifies the mechanical structure and circuit structure of the multimeter; in addition, the multiple first secondary switch circuits are arranged to cooperate with the sampling circuit, multiple ranges are flexibly realized, and a larger measurement range and higher resolution are further realized.

[0010] In an implementation manner, the sampling circuit comprises a first sampling unit and an Nth sampling unit connected in sequence, a second end of the first sampling unit and a first end of the Nth sampling unit are connected with the second node, a second end of the Nth sampling unit is connected with the access point, and the access point is connected with the first node, wherein N is an integer.

[0011] In an implementation manner, the signal output circuit comprises a selection unit and a first amplification unit, a first end of the selection unit is connected with the first node, a second end of the selection unit is connected with the second node, a first end of the first amplification unit is connected with a third end of the selection unit, and a second end of the first amplification unit is connected with the MCU.

[0012] In an implementation manner, the first amplification unit comprises an operational amplifier U2-A, resistors R21, R22, R23, R24, R42 and an analog switch U11-A, a non-inverting input end of the operational amplifier U2-A is connected with the third end of the selection unit through the resistor R21, an output end of the operational amplifier U2-A is connected with the MCU through an ADC, one end of the resistors R22, R42, R23 and R24 is connected with an inverting input end of the operational amplifier U2-A, the other end of the resistor R22 is grounded, input ends of the analog switch U11-A are respectively connected with the other ends of the resistors R42, R23 and R24, one output end of the analog switch U11-A is connected with the output end of the operational amplifier U2-A, and the other two output ends of the analog switch U11-A are connected with the MCU.

[0013] In an implementation manner, an insurance unit is connected between the input port and the front-stage protection and sampling switch module.

[0014] In an implementation manner, the first conducting unit comprises a first end connected with the input port, a second end connected with the second conducting unit, and a third end connected with the input current monitoring circuit; and the second conducting unit comprises a first end connected with the second end of the first conducting unit and the third node, a second end connected with the first end of the first conducting unit, and a third end connected with the input current monitoring circuit.

[0015] In an implementation manner, the first conducting unit is a field effect tube Q5, the second conducting unit is a field effect tube Q6, the first end of the first conducting unit is a drain, the second end of the first conducting unit is a source, and the third end of the first conducting unit is a gate; the first end of the second conducting unit is a drain, the second end of the second conducting unit is a source, and the third end of the second conducting unit is a gate.

[0016] In an implementation manner, the input current monitoring circuit comprises a second amplifying unit, a converting unit and a comparing unit connected in sequence, the second amplifying unit is connected with the third node, and the comparing unit is connected with the third end of the first switch circuit.

[0017] In an implementation manner, the second switch circuit comprises a third conducting unit and a fourth conducting unit, the first end of the third conducting unit is connected with the input port, the third end of the third conducting unit is connected with the MCU, the first end of the fourth conducting unit is connected with the second end of the third conducting unit and the access point, the second end of the fourth conducting unit is connected with the first end of the third conducting unit, and the third end of the fourth conducting unit is connected with the MCU.

[0018] In an implementation manner, the third conducting unit is a field effect tube Q11, the fourth conducting unit is a field effect tube Q12, the first end of the third conducting unit is a drain, the second end of the third conducting unit is a source, and the third end of the third conducting unit is a gate; the first end of the fourth conducting unit is a drain, the second end of the fourth conducting unit is a source, and the third end of the fourth conducting unit is a gate.

[0019] The application will be further described below in conjunction with the drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0021] Figure 1 is a structure block diagram of the invasive current measurement device in the embodiments of the present application;

[0022] Figure 2 is a connection structure block diagram of the first secondary switch circuit and the sampling circuit in the embodiment of the present application;

[0023] Figure 3 is a connection structure block diagram of the first secondary switch circuit and the second sampling unit in the embodiment of the present application;

[0024] Figure 4 is a connection structure block diagram of the selection unit and the first amplification unit in the embodiment of the present application;

[0025] Figure 5 is a circuit diagram of the first amplification unit in the embodiment of the present application;

[0026] Figure 6 is a connection structure block diagram of the first conduction unit and the second conduction unit in the embodiment of the present application;

[0027] Figure 7 is a connection structure block diagram of the input current monitoring circuit in the embodiment of the present application;

[0028] Figure 8 is a connection structure block diagram of the third conduction unit and the fourth conduction unit in the embodiment of the present application;

[0029] Figure 9 is a circuit diagram of the input sampling measurement module in the embodiment of the present application;

[0030] Figure 10 is a circuit diagram of the front-stage protection and sampling switch module in the embodiment of the present application;

[0031] Figure 11 is a circuit diagram of the rear-stage protection and sampling switch module in the embodiment of the present application; DETAILED DESCRIPTION

[0032] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in a variety of ways beyond the specific embodiments described herein without departing from the scope of the present application, and it will be apparent to those skilled in the art that similar modifications of the present application can be made without departing from the scope of the present application, and therefore the present application is not limited to the specific embodiments disclosed below.

[0033] In the description of the present application, it needs to be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0034] In the description of the present application, it needs to be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can be explicitly or implicitly included at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0035] In the embodiments of the present application, unless otherwise specifically defined and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0036] In the related art, when a multimeter is used to measure the current of a target, the current size needs to be estimated in advance, and then the input port and the range are selected manually. If the current value of the target to be measured is small and a large current measurement channel is selected, the reading is not accurate due to small resolution, affecting the measurement accuracy; if the current value of the target to be measured is large and a small current measurement channel is selected, the fuse tube of the small current measurement channel will be directly burned out, causing the multimeter to be damaged, so the multimeter needs to be repaired, which is very troublesome. The present application uses a single gear measurement and a common input port through an input sampling measurement module, a front-stage protection and sampling switch module and a rear-stage protection and sampling switch module, which effectively simplifies the mechanical structure and circuit structure of the multimeter. In addition, by setting a plurality of second-stage switch circuits in cooperation with the sampling circuit, a plurality of ranges are flexibly realized, further realizing a larger measurement range and higher resolution. In this way, the multimeter is prevented from being damaged due to misoperation.

[0037] Please refer to Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 ,Figure 7 、 Figure 8 、 Figure 9 、 Figure 10 and Figure 11 wherein, Figure 1 is a structural block diagram of an invasive current measurement device in the embodiment of the present application; Figure 2 is a connection structural block diagram of a first secondary switch circuit and a sampling circuit in the embodiment of the present application; Figure 3 is a connection structural block diagram of the first secondary switch circuit and a second sampling unit in the embodiment of the present application; Figure 4 is a connection structural block diagram of a selection unit and a first amplification unit in the embodiment of the present application; Figure 5 is a circuit diagram of the first amplification unit in the embodiment of the present application; Figure 6 is a connection structural block diagram of a first conduction unit and a second conduction unit in the embodiment of the present application; Figure 7 is a connection structural block diagram of an input current monitoring circuit in the embodiment of the present application; Figure 8 is a connection structural block diagram of a third conduction unit and a fourth conduction unit in the embodiment of the present application; Figure 9 is a circuit diagram of an input sampling measurement module in the embodiment of the present application; Figure 10 is a circuit diagram of a front-stage protection and sampling switch module in the embodiment of the present application; Figure 11 is a circuit diagram of a rear-stage protection and sampling switch module in the embodiment of the present application; the embodiment of the present application provides an invasive current measurement device, comprising an input sampling measurement module 100, a front-stage protection and sampling switch module 200 and a rear-stage protection and sampling switch module 300.

[0038] The input sampling measurement module 100 comprises an input port A, a sampling circuit 110, a signal output circuit 120, a first node a and a second node b, the input port A is connected with the first node a, a first end of the sampling circuit 110 and a first end of the signal output circuit 120 are connected with the first node a, a second end of the sampling circuit 110 and a second end of the signal output circuit 120 are connected with the second node b, and the sampling circuit 110 further has a plurality of access points s;

[0039] The front-stage protection and sampling switch module 200 comprises a first-stage switch circuit 210, an input current monitoring circuit 220 and a third node c, a first end of the first-stage switch circuit 210 is connected with the input port A, a second end of the first-stage switch circuit 210 and a first end of the input current monitoring circuit 220 are connected with the third node c, a second end of the input current monitoring circuit 220 is connected with a third end of the first-stage switch circuit 210, and the third node c is connected with the second node b;

[0040] The back-stage protection and sampling switch module 300 comprises a first secondary switch circuit 310, a first end of the first secondary switch circuit 310 is connected with the input port A, and a second end of the first secondary switch circuit 310 is connected with an access point s of the sampling circuit 110, wherein I≥1, I is an integer.

[0041] As shown in the figure, the measurement process of the present application is that the measured current is input from the input port A, passes through the fuse unit, the sampling circuit 110, the sampling signal of the sampling circuit 110 is received by the signal output circuit 120, and is amplified and converted into a digital signal, and then is transmitted to the MCU, and finally the measurement result is displayed on the LCD. Figure 1

[0042] Since the invasive current measurement device generally uses a low resistance for sampling, when measuring the current, the voltage drop of the device is relatively low, and there is no safety problem. However, when the user uses it improperly, the low-internal-resistance current measurement device is mistakenly connected to a high-voltage source, high-voltage and high-current will surge into the device, and the safety tube has a delay, and then the device will be burned out, and more seriously, a safety accident will occur. Therefore, the front-stage protection and sampling switch module 200 is arranged in the present application, so that the device has three safety protections, thereby effectively preventing the user from misoperation.

[0043] The three safety protections are introduced as follows,

[0044] The first safety protection is that, as shown in the figure, the first conduction unit (to be mentioned below) and the second conduction unit (to be mentioned below) in the first-stage switch circuit 210 can withstand a pulse current of 400A, and are directly connected in parallel with the back-stage circuit to be protected. When high-energy high-voltage is input, the high-energy current flows through the first conduction unit and the second conduction unit, realizing voltage clamping of the back-stage circuit, and at the same time, the current far exceeds the fuse current of the fuse unit, so that the fuse unit is quickly fused. Figure 1 The second safety protection is that, as shown in the figure, when the input current makes the parasitic diode in each of the first conduction unit and the second conduction unit rise, the first conduction unit and the second conduction unit are turned on, and after the first conduction unit and the second conduction unit are turned on, the input current bypasses the first conduction unit and the second conduction unit, and the bypass current far exceeds the fuse current of the fuse unit, so that the fuse unit is quickly fused.

[0045] Figure 1 The third safety protection is that, as shown in the figure, when the input current is too large, the input current bypasses the first conduction unit and the second conduction unit, and the bypass current far exceeds the fuse current of the fuse unit, so that the fuse unit is quickly fused.

[0046] Figure 7 ​​​As shown, the second amplification unit (mentioned below) samples and amplifies the total input current, and then the AC to DC conversion is performed by the conversion unit (mentioned below) to obtain the absolute value of the current sample. Finally, the comparison unit (mentioned below) forms the monitoring of the input current. When the input current is detected to be greater than 100mA, a high level is immediately output, and then the first conduction unit and the second conduction unit are controlled to quickly conduct to protect the subsequent circuit.

[0047] Furthermore, since the pre-stage protection and sampling switch module 200 has clamped the circuit behind the fuse unit to a lower voltage, the subsequent stage uses the subsequent stage protection and sampling switch module 300 to select the corresponding sampling circuit 110. In the subsequent stage protection and sampling switch module 300, the first-level switch circuit 310 is selected by the MCU based on the current range to select the corresponding sampling circuit 110.

[0048] like Figure 2 As shown, the first-level switching circuit 310 can be a first-level switching circuit, a second-level switching circuit, a third-level switching circuit, and so on. Each first-level switching circuit 310 is controlled by the MCU and corresponds to a specific sampling resistor. This allows for flexible implementation of more measurement ranges, and by cooperating with the signal output circuit 120, a larger measurement range and higher resolution can be achieved.

[0049] In some examples, the sampling circuit 110 includes a first sampling unit and an Nth sampling unit connected in sequence. The second end of the first sampling unit and the first end of the Nth sampling unit are connected to the second node b. The second end of the Nth sampling unit is connected to the access point s. The access point s is connected to the first node a. Here, N = 1 + 1, and N is an integer.

[0050] The number of access points 's' corresponds to the number of sampling units. For example, such as... Figure 3 As shown, when there are two sampling units, that is, when the sampling circuit 110 has a first sampling unit and a second sampling unit, there is one access point s.

[0051] For example, when there are three sampling units, that is, when the sampling circuit 110 has a first sampling unit, a second sampling unit and a third sampling unit, then there are two access points s.

[0052] The following describes the relationship between the first-level switching circuit 310 and the Nth sampling unit. For example, as... Figure 3As shown, when I is 1 and N is 2, the back-stage protection and sampling switch module 300 has a first secondary switch circuit, and the sampling circuit 110 has a first sampling unit and a second sampling unit. The second end of the first secondary switch circuit and the second end of the second sampling unit are commonly connected to the access point s, and the access point s is connected to the input end of a selection unit (to be mentioned below). At this time, the resistance of the sampling circuit 110 is the resistance of the first sampling unit plus the resistance of the second sampling unit. In this way, the selection unit obtains the sampling voltage on the first sampling unit and the second sampling unit, and then sends it to the ADC measurement through the first amplification unit (to be mentioned below), and then controls the LCD display by the MCU.

[0053] The first sampling unit is a thick copper wire resistance that can withstand instantaneous current of 1000A or more, and the resistance R25 has a resistance of 0.01Ω.

[0054] The second sampling unit is a resistance R20, and the resistance R20 has a resistance of 0.1Ω.

[0055] For example, if N is 3, the third sampling unit is a resistance R19, and the resistance R19 has a resistance of 10Ω. At this time, I is 2, and the corresponding resistance controlled by the second secondary switch circuit is the sum of the resistances of the first sampling unit, the second sampling unit and the third sampling unit.

[0056] For example, if N is 4, the fourth sampling unit is a resistance R18, and the resistance R18 has a resistance of 100Ω. At this time, I is 3, and the corresponding resistance controlled by the third secondary switch circuit is the sum of the resistances of the first sampling unit, the second sampling unit, the third sampling unit and the fourth sampling unit.

[0057] In some examples, the signal output circuit 120 includes a selection unit 121 and a first amplification unit 122. The first end of the selection unit 121 is connected to the first node a, the second end of the selection unit 121 is connected to the second node b, the first end of the first amplification unit 122 is connected to the third end of the selection unit 121, and the second end of the first amplification unit 122 is connected to the MCU.

[0058] As shown in Figure 5 and Figure 9 The selection unit 121 has a plurality of input ends, and these input ends are respectively connected to the second node b and each access point s. In this way, the selection unit 121 is controlled by the MCU, and is used to select different sampling voltage signals and output to the first amplification unit 122.

[0059] Continuing as shown in Figure 5 and Figure 9As shown, the first amplification unit 122 is configured to receive the sampling voltage signal and amplify it by 1 times, 10 times or 100 times. In this way, a single sampling unit corresponds to three ranges, thereby flexibly realizing any number of ranges while having high resolution and extremely wide measurement range.

[0060] For example, as shown in FIG. 1, when the MCU controls the first-stage switch circuit 210 to be turned on, the measurement current will pass through the first-stage switch circuit 210 and the first sampling unit, the selection unit 121 is switched to the sampling voltage channel of the first sampling unit, and the ADC reads the voltage on the first sampling unit. Figure 3 , Figure 5 and Figure 9 When the value read is greater than 100 mV, the MCU controls the first-stage switch circuit to be turned on and the second-stage switch circuit to be turned off, i.e., the first sampling unit is selected.

[0061] When the value read is greater than 100 mV, the MCU controls the first-stage switch circuit to be turned on and the second-stage switch circuit to be turned off, i.e., the first sampling unit is selected.

[0062] The selection unit 121 is an analog switch U1.

[0063] In some examples, the first amplification unit 122 includes an operational amplifier U2-A, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R42 and an analog switch U11-A, the non-inverting input terminal of the operational amplifier U2-A is connected to the third terminal of the selection unit 121 through the resistor R21, the output terminal of the operational amplifier U2-A is connected to the MCU through the ADC, one end of the resistor R22, the resistor R42, the resistor R23 and the resistor R24 is connected to the inverting input terminal of the operational amplifier U2-A, the other end of the resistor R22 is grounded, the input terminals of the analog switch U11-A are respectively connected to the other ends of the resistor R42, the resistor R23 and the resistor R24, one output terminal of the analog switch U11-A is connected to the output terminal of the operational amplifier U2-A, and the other two output terminals of the analog switch U11-A are connected to the MCU.

[0064] The ADC usually has an input range with best accuracy, so the measured signal input to the ADC needs to be within this range to obtain the best measurement accuracy. For example, as shown in FIG. 1, when the value read by the ADC is less than 10 mV, the MCU opens the first-stage switch circuit and the second-stage switch circuit, and closes the first-stage switch circuit 210, so that the measurement current passes through the first-stage switch circuit 210, the second sampling unit and the first sampling unit, and the ADC reads the sampling voltage on the second sampling unit and the first sampling unit. Figure 9As shown, assuming that the optimal precision range of the ADC is 10 to 100 mV, when the first and second conduction units are turned on, i.e., the first-stage switching circuit 210 is turned on, the ADC measures the sampling voltage on the first sampling unit. When the measured current is less than 0.1 A, the sampling voltage on the first sampling unit will be less than 1 mV, which is not within the optimal precision range of the ADC. The MCU will control the analog switch U11-A and select the resistance R23 to be connected as the negative feedback resistance of the operational amplifier U2-A, so that the operational amplifier U2-A, the resistance R22, and the resistance R23 form a 10 times amplification circuit. At this time, the MCU reads the measurement value of the ADC, which is less than 10 mV, and still not within the optimal precision range. The MCU will again control the analog switch U11-A and select the resistance R42 to be connected as the negative feedback resistance of the operational amplifier U2-A, so that the operational amplifier U2-A, the resistance R22, and the resistance R42 form a 100 times amplification circuit. The amplified voltage falls within the optimal precision range, and the ADC can accurately measure the voltage amplified by 100 times. The MCU further calculates the size of the measured current according to the measurement value of the ADC, the amplification multiple of the first amplification unit 122, and the size of the sampling unit.

[0065] For example, the ADC reads a voltage of 100 mV, the amplification multiple of the first amplification unit 122 is 100 times, and the first sampling resistance has a resistance value of 0.01 Ω. Then, the size of the measured current can be calculated as 100 divided by 100 divided by 0.01, which is equal to 10 A. Similarly, when the measured current is less than 1 A but greater than 0.1 A, the MCU configures the first amplification unit 122 to have a multiple of 10 times. When the measured current is less than 10 A but greater than 1 A, the MCU configures the first amplification unit 122 to have a multiple of 1 time. In this way, a single sampling unit has three ranges, which achieves accurate measurement of a wider current range with fewer sampling units, simplifies the circuit structure, and reduces the number of circuit components.

[0066] In some examples, the input port A is connected with the fuse unit 400 between the front-stage protection and sampling switch module 200. The fuse unit 400 is a fuse tube F1.

[0067] In some examples, the first-stage switching circuit 210 includes a first conduction unit 211 and a second conduction unit 212. The first end of the first conduction unit 211 is connected to the input port A, and the third end of the first conduction unit 211 is connected to the input current monitoring circuit 220. The first end of the second conduction unit 212 is connected to the second end of the first conduction unit 211 and to the third node c, and the second end of the second conduction unit 212 is connected to the first end of the first conduction unit 211. The third end of the second conduction unit 212 is connected to the input current monitoring circuit 220. The first conduction unit 211 is a field effect transistor Q5, the second conduction unit 212 is a field effect transistor Q6, the first end of the first conduction unit 211 is a drain, the second end of the first conduction unit 211 is a source, and the third end of the first conduction unit 211 is a gate. The first end of the second conduction unit 212 is a drain, the second end of the second conduction unit 212 is a source, and the third end of the second conduction unit 212 is a gate.

[0068] As shown in FIG. 1, the first conduction unit 211 and the second conduction unit 212 are connected in anti-parallel to each other and then connected to the sampling circuit 110, thereby effectively protecting the subsequent protection and sampling switching module 300 and achieving voltage clamping of the subsequent protection and sampling switching module 300. Figure 6

[0069] For example, as shown in FIG. 2, in the first-stage protection, the parasitic diodes in the field effect transistor Q5 and the field effect transistor Q6 can withstand a pulse current of 400 A and are directly connected in parallel to the subsequent circuit to be protected. When high-energy high-voltage input is applied, the high-energy current flows through the field effect transistor Q5 and the field effect transistor Q6, thereby achieving voltage clamping of the subsequent circuit. At the same time, the current far exceeds the fusing current of the fuse unit 400, so that the fuse unit 400 is quickly fused. Figure 10

[0070] The second-stage protection is shown in FIG. 3. When the input current causes the parasitic diodes in the field effect transistor Q5 and the field effect transistor Q6 to rise, the voltage generated by the input current is applied to the gates of the field effect transistor Q5 and the field effect transistor Q6 through the diode D3, the capacitor C2, the resistor R6, and the resistor R7 or the diode D2, the capacitor C1, the resistor R8, and the resistor R9, so that the field effect transistor Q5 and the field effect transistor Q6 are turned on. After the field effect transistor Q5 and the field effect transistor Q6 are turned on, the resistance of the source and the drain is very small, so the input current bypasses the field effect transistor Q5 and the field effect transistor Q6. The bypass current far exceeds the fusing current of the fuse unit 400, so that the fuse unit 400 is quickly fused. Figure 10

[0071] ​​​In the second layer of protection, since the input current and voltage may be positive, negative or AC, the field-effect transistors Q5 and Q6 are connected in parallel with diode D3, capacitor C2 and resistor R6 and resistor R7 or diode D2, capacitor C1 and resistor R8 and resistor R9 in a symmetrical design. Among them, capacitors C1 and C2 have the function of accelerating the conduction of field-effect transistors Q5 and Q6.

[0072] In some examples, the input current monitoring circuit 220 includes a second amplification unit 221, a conversion unit 222 and a comparison unit 223 connected in sequence. The second amplification unit 221 is connected to the third node c, and the comparison unit 223 is connected to the third terminal of the first-stage switching circuit 210.

[0073] like Figure 10 As shown, the second amplification unit 221 may include operational amplifier U4-A, resistor R39, resistor R40, and resistor R41. Operational amplifier U4-A, resistor R39, resistor R40, and resistor R41 together form a 100 amplifier to sample and amplify the total input current.

[0074] The conversion unit 222 may include operational amplifier U4-D, operational amplifier U4-C, resistors R33, R34, R35, R36, R37, R38, diodes D4, D5, and D6. The conversion unit 222 receives the signal amplified by the total input current sampling from the second amplification unit 221 and then obtains the absolute value of the current sample.

[0075] The comparator unit 223 may include an operational amplifier U4-B. The comparator unit 223 compares the absolute value of the current sampled by the conversion unit 222 with a 1.2V voltage to form a detection of the input current. For example, when the input current is detected to be greater than 100mA, the output is high, which controls the field-effect transistors Q5 and Q6 to quickly conduct and protect the subsequent circuitry through transistors Q1 and Q2.

[0076] Thus, the second amplification unit 221, conversion unit 222 and comparison unit 223 of the input current monitoring circuit 220 achieve the third layer of protection for this device.

[0077] In some examples, the first secondary switch circuit 310 includes a third conducting unit 311 and a fourth conducting unit 312. The first end of the third conducting unit 311 is connected to the input port A, the third end of the third conducting unit 311 is connected to the MCU, the first end of the fourth conducting unit 312 is connected to the second end of the third conducting unit 311 and the access point s, the second end of the fourth conducting unit 312 is connected to the first end of the third conducting unit 311, and the third end of the fourth conducting unit 312 is connected to the MCU. The third conducting unit 311 is a field effect tube Q11, the fourth conducting unit 312 is a field effect tube Q12, the first end of the third conducting unit 311 is a drain, the second end of the third conducting unit 311 is a source, the third end of the third conducting unit 311 is a gate, the first end of the fourth conducting unit 312 is a drain, the second end of the fourth conducting unit 312 is a source, and the third end of the fourth conducting unit 312 is a gate.

[0078] As shown in Figure 11 , the first secondary switch circuit 310 can include a resistor R10, a resistor R12, a resistor R11, a resistor R13, a triode Q7, a triode Q8, a triode Q9, a triode Q10, a field effect tube Q11, and a field effect tube Q12.

[0079] For example, as shown in Figure 3 , Figure 8 , Figure 10 , after the field effect Q5 and the field effect tube Q6 of the primary switch circuit 210 are turned on, the resistor R25 of the sampling circuit 110 is selected as the sampling resistor, and the sampling resistors other than the resistor R25 are protected in parallel. Assuming that the measured current is 8 mA, the sampling voltage on the resistor R25 is 0.01 times 8, which is equal to 0.08 mV. At this time, the MCU configures the first amplification unit 122 to amplify 100 times, and the amplified voltage is 8 mV, which is less than the accuracy range of the ADC of 10 to 100 mV. At this time, the second output end of the MCU outputs a high level, the first output end of the MCU outputs a low level, the high level of the second output end of the MCU is added to the base of the triode Q7 through the resistor R10 to make the triode Q7 conductive, the triode Q7 is conductive, the base level of the triode Q8 is connected to the field effect tube Q12 to make the triode Q8 conductive, the triode Q8 is conductive, and the high level is applied to the G pole of the field effect tube Q11 and the field effect tube Q12 to make the field effect tube Q11 and the field effect tube Q12 conductive, that is, the first secondary switch circuit is conductive, the sampling circuit 110 (i.e., the resistor R25 and the resistor R20) connected in parallel to the first secondary switch circuit is protected, and at the same time, the measured current flows through the resistor R25 and the resistor R20 to obtain the sampling voltage. The sampling voltage is sent to the first amplification unit 122 through the analog switch U1 and the resistor R21, and then sent to the ADC for measurement.

[0080] In the above-mentioned secondary stage I switching circuit 310, the triode Q9 and the triode Q10 constitute a voltage clamping protection circuit. When the voltage across the triode Q9 and the triode Q10 is greater than 9V, the triode Q9 and the triode Q10 will be soft-broken and conduct, clamping the G-pole voltage of the field effect transistor Q11 and the field effect transistor Q12, thereby protecting the field effect transistor Q11 and the field effect transistor Q12.

[0081] The technical features of the above embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0082] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present application, or modify it into equivalent embodiments without departing from the scope of the technical solution of the present application, using the methods and technical contents disclosed above. Therefore, any equivalent changes made to the shape, structure and principle of the present application without departing from the scope of the technical solution of the present application should be covered within the protection scope of the present application.

Claims

1. An invasive current measuring device, characterized in that, include: The input sampling measurement module includes an input port, a sampling circuit, a signal output circuit, a first node, and a second node. The input port is connected to the first node. The first end of the sampling circuit and the first end of the signal output circuit are connected to the first node. The second end of the sampling circuit and the second end of the signal output circuit are connected to the second node. The sampling circuit also has multiple access points. The pre-stage protection and sampling switch module includes a primary switch circuit, an input current monitoring circuit, and a third node. The first terminal of the primary switch circuit is connected to the input port, the second terminal of the primary switch circuit and the first terminal of the input current detection circuit are connected to the third node, the second terminal of the input current monitoring circuit is connected to the third terminal of the primary switch circuit, and the third node is connected to the second node. The first-level switching circuit includes a first conducting unit and a second conducting unit. The first end of the first conducting unit is connected to the input port, and the third end of the first conducting unit is connected to the input current monitoring circuit. The first end of the second conducting unit is connected to the second end of the first conducting unit and is also connected to the third node. The second end of the second conducting unit is connected to the first end of the first conducting unit, and the third end of the second conducting unit is connected to the input current monitoring circuit. The post-stage protection and sampling switch module includes a first-stage switching circuit. The first terminal of the first-stage switching circuit is connected to the input port, and the second terminal of the first-stage switching circuit is connected to an access point of the sampling circuit, wherein I ≥ 1 and I is an integer.

2. The invasive current measuring device according to claim 1, characterized in that, The sampling circuit includes a first sampling unit and an Nth sampling unit connected in sequence. The second end of the first sampling unit and the first end of the Nth sampling unit are connected to the second node. The second end of the Nth sampling unit is connected to the access point. The access point is connected to the first node. Wherein, N = 1 + 1, and N is an integer.

3. The invasive current measuring device according to claim 1, characterized in that, The signal output circuit includes a selection unit and a first amplification unit. The first end of the selection unit is connected to the first node, the second end of the selection unit is connected to the second node, the first end of the first amplification unit is connected to the third end of the selection unit, and the second end of the first amplification unit is connected to the MCU.

4. The invasive current measuring device according to claim 3, characterized in that, The first amplification unit includes an operational amplifier U2-A, resistors R21, R22, R23, R24, R42, and an analog switch U11-A. The non-inverting input of the operational amplifier U2-A is connected to the third terminal of the selection unit through circuit R21. The output of the operational amplifier U2-A is connected to the MCU through an ADC. One end of resistors R22, R42, R23, and R24 is connected to the inverting input of the operational amplifier U2-A, and the other end of resistor R22 is grounded. The input of the analog switch U11-A is connected to the other ends of resistors R42, R23, and R24, respectively. One output of the analog switch U11-A is connected to the output of the operational amplifier U2-A, and the other two outputs of the analog switch U11-A are connected to the MCU.

5. The invasive current measuring device according to claim 1, characterized in that, A fuse unit is connected between the input port and the pre-stage protection and sampling switch module.

6. The invasive current measuring device according to claim 1, characterized in that, The first conducting unit is a field-effect transistor Q5, the second conducting unit is a field-effect transistor Q6, the first end of the first conducting unit is the drain, the second end of the first conducting unit is the source, and the third end of the first conducting unit is the gate. The first end of the second conducting unit is the drain, the second end of the second conducting unit is the source, and the third end of the second conducting unit is the gate.

7. The invasive current measuring device according to claim 1, characterized in that, The input current monitoring circuit includes a second amplification unit, a conversion unit, and a comparison unit connected in sequence. The second amplification unit is connected to the third node, and the comparison unit is connected to the third terminal of the first-stage switching circuit.

8. The invasive current measuring device according to claim 1, characterized in that, The first-level switching circuit includes a third conduction unit and a fourth conduction unit. The first end of the third conduction unit is connected to the input port, and the third end of the third conduction unit is connected to the MCU. The first end of the fourth conduction unit is connected to the second end of the third conduction unit and to the access point. The second end of the fourth conduction unit is connected to the first end of the third conduction unit, and the third end of the fourth conduction unit is connected to the MCU.

9. The invasive current measuring device according to claim 1, characterized in that, The third conducting unit is a field-effect transistor Q11, and the fourth conducting unit is a field-effect transistor Q12. The first terminal of the third conducting unit is the drain, the second terminal of the third conducting unit is the source, and the third terminal of the third conducting unit is the gate. The first terminal of the fourth conducting unit is the drain, the second terminal of the fourth conducting unit is the source, and the third terminal of the fourth conducting unit is the gate.

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