CN116106607A - Invasive current measuring device - Google Patents

Abstract

The application belongs to the technical field of current measurement equipment, and particularly relates to an invasive current measurement device, which comprises an input sampling measurement module, a sampling circuit, a signal output circuit, a first node and a second node, wherein the input sampling measurement module comprises an input port, a sampling circuit, a signal output circuit and a first 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 post-stage protection and sampling switch module comprises a second-stage switch circuit; according to the universal meter, the input sampling measurement module, the front-stage protection and sampling switch module and the rear-stage protection and sampling switch module adopt single gear measurement and share the input port, so that the mechanical structure and the circuit structure of the universal meter are effectively simplified; in addition, through setting up a plurality of I second grade switch circuit and sampling circuit cooperation, realize a plurality of ranges in a flexible way, further realize bigger measuring range and higher resolution.

Description

Invasive current measuring device

Technical Field

The present disclosure relates to the field of current measurement technologies, and in particular, to an invasive current measurement device.

Background

In the related art, when a multimeter is used to measure a current of a target, the current is estimated in advance, and then the input port and the measuring range are manually selected. If the current value of the target to be measured is smaller and a large current measuring channel is selected, the reading is inaccurate due to small resolution, and the measuring precision is affected; if the current value of the object to be measured is bigger and the small current measuring channel is selected, the fuse tube of the small current measuring channel can be directly burnt out, so that the universal meter is damaged, and the universal meter is required to be maintained, thus being very troublesome.

It should be noted that the information disclosed in the above background section is only for enhancing understanding of the background of the present disclosure and thus may include information that does not form the prior art that is already known to those of ordinary skill in the art.

Disclosure of Invention

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 a current of a target, the current needs to be estimated in advance, and then an input port and a measuring range are manually selected. If the current value of the target to be measured is smaller and a large current measuring channel is selected, the reading is inaccurate due to small resolution, and the measuring precision is affected; if the current value of the object to be measured is bigger and the small current measuring channel is selected, the fuse tube of the small current measuring channel can be directly burnt out, and the universal meter is damaged, so that the universal meter is required to be maintained, and the problem of great trouble is solved.

An embodiment of the present application provides an invasive current measurement device, including:

the input sampling measurement module comprises an input port, a sampling circuit, a signal output circuit, a first node and a second node, wherein the input port is connected with the first node, the first end of the sampling circuit and the first end of the signal output circuit are connected with the first node, the second end of the sampling circuit and the second end of the signal output circuit are connected with the second node, and a plurality of access points are arranged on the sampling circuit;

the front-stage protection and sampling switch module comprises a first-stage switch circuit, an input current monitoring circuit and a third node, wherein the first end of the first-stage switch circuit is connected with an input port, the second end of the first-stage switch circuit and the first end of the input current detection circuit are connected with the third node, the second end of the input current monitoring circuit is connected with the third end of the first-stage switch circuit, and the third node is connected with the second node;

the post-stage protection and sampling switch module comprises an I second-stage switch circuit, wherein the first end of the I second-stage switch circuit is connected with the input port, the second end of the I second-stage switch circuit is connected with an access point of the sampling circuit, I is more than or equal to 1, and I is an integer.

The application has the following technical effects: according to the universal meter, the input sampling measurement module, the front-stage protection and sampling switch module and the rear-stage protection and sampling switch module adopt single gear measurement and share the input port, so that the mechanical structure and the circuit structure of the universal meter are effectively simplified; in addition, through setting up a plurality of I second grade switch circuit and sampling circuit cooperation, realize a plurality of ranges in a flexible way, further realize bigger measuring range and higher resolution.

In one implementation, the sampling circuit includes a first sampling unit and an nth sampling unit connected in sequence, a second end of the first sampling unit, a first end of the nth sampling unit is connected with a second node, a second end of the nth sampling unit is connected with an access point, the access point is connected with the first node, wherein n=i+1, and N is an integer.

In one implementation, the signal output circuit includes 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.

In one implementation, the first amplifying unit 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 end of the operational amplifier U2-A is connected with the third end of the selecting unit through a circuit R21, the output end of the operational amplifier U2-A is connected with the MCU through the ADC, one end of the resistor R22, the resistor R42, the resistor R23 and the resistor R24 is connected with the inverting input end of the operational amplifier U2-A, the other end of the resistor R22 is grounded, the input end of the analog switch U11-A is connected with the other ends of the resistor R42, the resistor R23 and the resistor 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.

In one implementation, a safety unit is connected between the input port and the front-stage protection and sampling switch module.

In one implementation, the first-stage switching circuit includes a first conducting unit and a second conducting unit, a first end of the first conducting unit is connected with the input port, a third end of the first conducting unit is connected with the input current monitoring circuit, a first end of the second conducting unit is connected with a second end of the first conducting unit and is connected with the third node, a second end of the second conducting unit is connected with the first end of the first conducting unit, and a third end of the second conducting unit is connected with the input current monitoring circuit.

In one implementation, 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 a drain, the second end of the first conducting unit is a source, the third end of the first conducting unit is a gate, the first end of the second conducting unit is a drain, the two ends of the second conducting unit are sources, and the third end of the second conducting unit is a gate.

In one implementation, the input current monitoring circuit includes a second amplifying unit, a converting unit and a comparing unit connected in sequence, the second amplifying unit is connected with a third node, and the comparing unit is connected with a third end of the primary switching circuit.

In one implementation, the second-stage switching circuit includes a third conducting unit and a fourth conducting unit, a first end of the third conducting unit is connected with the input port, a third end of the third conducting unit is connected with the MCU, a first end of the fourth conducting unit is connected with a second end of the third conducting unit and is connected with the access point, a second end of the fourth conducting unit is connected with a first end of the third conducting unit, and a third end of the fourth conducting unit is connected with the MCU.

In one implementation, the third conducting unit is a field effect transistor Q11, the fourth conducting unit is a field effect transistor Q12, the first end of the third conducting unit is a drain, the second end of the third conducting unit is a source, the third end of the third conducting unit is a gate, the first end of the fourth conducting unit is a drain, the two ends of the fourth conducting unit are sources, and the third end of the fourth conducting unit is a gate.

The invention will be further described with reference to the drawings and examples.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will briefly explain the embodiments or the drawings needed in the prior art, and it is obvious that the drawings in the following description are only some embodiments of the present invention and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a block diagram of an invasive current measurement apparatus in an embodiment of the present application;

FIG. 2 is a block diagram showing the connection structure of the second stage switching circuit and the sampling circuit in the embodiment of the present application;

FIG. 3 is a block diagram showing a connection structure of a first two-stage switch circuit and a second sampling unit according to an embodiment of the present application;

fig. 4 is a block diagram of a connection structure of the selection unit and the first amplification unit in the embodiment of the present application;

fig. 5 is a circuit diagram of a first amplifying unit in the embodiment of the present application;

fig. 6 is a block diagram of a connection structure of a first conduction unit and a second conduction unit in an embodiment of the present application;

FIG. 7 is a block diagram of the connection structure of the input current monitoring circuit in the embodiment of the present application;

fig. 8 is a block diagram of a connection structure of the third conduction unit and the fourth conduction unit in the embodiment of the present application;

FIG. 9 is a circuit diagram of an input sample measurement module in an embodiment of the present application;

FIG. 10 is a circuit diagram of a front-end protection and sampling switch module in an embodiment of the present application;

FIG. 11 is a circuit diagram of a post-stage protection and sampling switch module in an embodiment of the present application;

Detailed Description

In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is, however, susceptible of embodiment in many other forms than those described herein and similar modifications can be made by those skilled in the art without departing from the spirit of the application, and therefore the application is not to be limited to the specific embodiments disclosed below.

In the description of the present application, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, merely to facilitate description of the present application and simplify the description, and do not indicate or imply that the devices or elements being referred to must have a specific orientation, be configured and operated in a specific orientation, and are not to be construed as limiting the present application.

In the description of the present application, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or an implicit indication of the number of technical features being indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless explicitly defined otherwise.

In the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to the specific circumstances.

In the related art, when a multimeter is used to measure a current of a target, the current is estimated in advance, and then the input port and the measuring range are manually selected. If the current value of the target to be measured is smaller and a large current measuring channel is selected, the reading is inaccurate due to small resolution, and the measuring precision is affected; if the current value of the object to be measured is bigger and the small current measuring channel is selected, the fuse tube of the small current measuring channel can be directly burnt out, so that the universal meter is damaged, and the universal meter is required to be maintained, thus being very troublesome. According to the universal meter, the input sampling measurement module, the front-stage protection and sampling switch module and the rear-stage protection and sampling switch module adopt single gear measurement and share the input port, so that the mechanical structure and the circuit structure of the universal meter are effectively simplified; in addition, through setting up a plurality of I second grade switch circuit and sampling circuit cooperation, realize a plurality of ranges in a flexible way, further realize bigger measuring range and higher resolution, so, avoided the mistake input operation to damage the universal meter.

Referring to fig. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11, fig. 1 is a block diagram of an invasive current measuring apparatus according to an embodiment of the present application; FIG. 2 is a block diagram showing the connection structure of the second stage switching circuit and the sampling circuit in the embodiment of the present application; FIG. 3 is a block diagram showing a connection structure of a first two-stage switch circuit and a second sampling unit according to an embodiment of the present application; fig. 4 is a block diagram of a connection structure of the selection unit and the first amplification unit in the embodiment of the present application; fig. 5 is a circuit diagram of a first amplifying unit in the embodiment of the present application; fig. 6 is a block diagram of a connection structure of a first conduction unit and a second conduction unit in an embodiment of the present application; FIG. 7 is a block diagram of the connection structure of the input current monitoring circuit in the embodiment of the present application; fig. 8 is a block diagram of a connection structure of the third conduction unit and the fourth conduction unit in the embodiment of the present application; FIG. 9 is a circuit diagram of an input sample measurement module in an embodiment of the present application; FIG. 10 is a circuit diagram of a front-end protection and sampling switch module in an embodiment of the present application; FIG. 11 is a circuit diagram of a post-stage protection and sampling switch module in an embodiment of the present application; the embodiment of the application provides an invasive current measuring device, which comprises an input sampling measuring module 100, a front-stage protection and sampling switch module 200 and a rear-stage protection and sampling switch module 300.

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, wherein 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 a plurality of access points s are arranged on the sampling circuit 110;

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, wherein a first end of the first-stage switch circuit 210 is connected with an input port A, a second end of the first-stage switch circuit 210 and a first end of the input current detection circuit 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 a second node b;

the post-stage protection and sampling switch module 300 comprises an I second stage switch circuit 310, wherein a first end of the I second stage switch circuit 310 is connected with an input port A, a second end of the I second stage switch circuit 310 is connected with an access point s of the sampling circuit 110, and I is more than or equal to 1 and is an integer.

As shown in fig. 1, in the measurement process of the present application, the measured current is input from the input port a, passes through the safety unit and the sampling circuit 110, the signal output circuit 120 receives the sampling signal of the sampling circuit 110, and is amplified, converted into a digital signal, and then transmitted to the MCU, and finally the measurement result is displayed on the LCD.

Since invasive current measuring devices typically use low resistance for sampling, the voltage drop across the device is relatively low and there is no safety issue when measuring current. However, when the user uses improperly, the low internal resistance current measuring device is connected to the high voltage source by mistake, the high voltage and high current flow into the device, and the protective tube has time delay, so that the device is burnt out, and safety accidents occur more seriously. Therefore, the pre-protection and sampling switch module 200 is arranged, so that the device has triple safety protection, and misoperation of a user is effectively prevented.

The triple safety protection is described below,

the first re-protection is that, as shown in fig. 1, the first conducting unit (to be mentioned later) and the second conducting unit (to be mentioned later) in the primary switch circuit 210 can bear 400A of pulse current, and are directly connected in parallel to the subsequent circuit to be protected. When high-energy high-voltage input is carried out, high-energy current flows through the first conduction unit and the second conduction unit, voltage clamping of a later-stage circuit is achieved, and meanwhile, the current far exceeds the fusing current of the fuse unit, so that the fuse unit is fused quickly.

The second protection is that, as shown in fig. 1, when the input current makes the parasitic diodes in the first conduction unit and the second conduction unit rise, the first conduction unit and the second conduction unit are conducted, after the first conduction unit and the second conduction unit are conducted, the input current bypasses the first conduction unit and the second conduction unit, and the bypass current is far beyond the fusing current of the fuse unit, so that the fuse unit is fused quickly.

The third protection is that, as shown in fig. 7, the second amplifying unit (to be mentioned later) amplifies the total input current, then performs ac-dc conversion through the converting unit (to be mentioned later) to obtain the absolute value of the current sample, finally, monitors the input current through the comparing unit (to be mentioned later), and when the input current is monitored to be greater than 100mA, immediately outputs a high level, and then controls the first conducting unit and the second conducting unit to conduct rapidly to protect the subsequent circuit.

In addition, since the front-end protection and sampling switch module 200 has clamped the circuit at the rear end of the fuse at a lower voltage, the rear-end protection and sampling switch module 300 is employed by the rear-end protection and sampling switch module 300 to select the corresponding sampling circuit 110. In the post-stage protection and sampling switch module 300, the second stage switch circuit 310 is an MCU that selects the corresponding sampling circuit 110 according to the current range.

As shown in fig. 2, the second stage switching circuits 310 may be a first stage switching circuit, a second stage switching circuit, a third stage switching circuit, and so on, so that each second stage switching circuit 310 is controlled by the MCU and corresponds to a corresponding sampling resistor. In this way, more ranges can be flexibly achieved, and by cooperating with the signal output circuit 120, a larger measurement range and higher resolution are achieved.

In some examples, the sampling circuit 110 includes a first sampling unit and an nth sampling unit connected in sequence, a second end of the first sampling unit, a first end of the nth sampling unit is connected with the second node b, a second end of the nth sampling unit is connected with the access point s, and the access point s is connected with the first node a, where n=i+1, and N is an integer.

The number of access points s corresponds to the number of sampling units. For example, as shown in fig. 3, when there are two sampling units, i.e. the sampling circuit 110 has a first sampling unit and a second sampling unit, there is one access point s.

For another example, when there are three sampling units, i.e., the sampling circuit 110 has a first sampling unit, a second sampling unit and a third sampling unit, there are two access points s.

The relationship between the second stage switch circuit 310 and the nth sampling unit is described below. For example, as shown in fig. 3, when I is 1 and N is 2, the post-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 terminal of the first two-stage switching circuit is commonly connected with the second terminal of the second sampling unit at an access point s, and the access point s is connected with an input terminal of a selection unit (to be mentioned later). 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. Thus, the selection unit obtains the sampling voltages of the first sampling unit and the second sampling unit, and sends the sampling voltages to the ADC for measurement through the first amplifying unit (to be mentioned later), and the MCU controls the LCD for display.

The first sampling unit is a resistor R25, and the first sampling unit is a blister copper wire resistor capable of bearing a current of more than 1000A at the moment, and the resistance value of the resistor R25 is 0.01Ω.

The second sampling unit is a resistor R20, and the resistance value of the resistor R20 is 0.1Ω.

For example, if N is 3, the third sampling unit is a resistor R19, and the resistance value of the resistor R19 is 10Ω. At this time, I is 2, and the corresponding resistance value controlled by the second level switch circuit is the sum of the first sampling unit, the second sampling unit and the third sampling unit.

For example, if N is 4, the fourth sampling unit is a resistor R18, and the resistance value of the resistor R18 is 100deg.OMEGA. At this time, if I is 3, the corresponding resistance value controlled by the third second-stage switch circuit is the sum of the first sampling unit, the second sampling unit, the third sampling unit and the fourth sampling unit.

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

As shown in fig. 5 and 9, the selecting unit 121 has a plurality of input terminals, and these input terminals are respectively connected to the second node b and each access point s. Thus, the selecting unit 121 is controlled by the MCU, and is used for selecting different sampling voltage signals and outputting the signals to the first amplifying unit 122.

As further shown in fig. 5 and 9, the first amplifying unit 122 is configured to receive the sampled voltage signal and amplify the sampled voltage signal by 1 time, 10 times or 100 times. Thus, a single sampling unit is correspondingly provided with three measuring ranges, so that any number of measuring ranges can be flexibly realized, and the device has high resolution and extremely wide measuring range.

For example, as shown in fig. 3, 5 and 9, when the MCU controls the primary switch circuit 210 to be turned on, the measurement current passes through the primary 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. When the first amplifying unit 122 is configured to amplify 100 times, and the voltage read by the first sampling unit is still less than 10mV, the MCU turns on the first secondary switching circuit and simultaneously turns off the primary switching circuit 210, the measurement current passes through the first secondary switching circuit, the second sampling unit and the first sampling unit, and the ADC reads the sampled voltages on the second sampling unit and the first sampling unit.

Otherwise, when the read value is greater than 100mV, the MCU controls the first-stage open-circuit to be conducted, and closes the first secondary switch circuit, namely, selects the first sampling unit.

Wherein the selection unit 121 is an analog switch U1.

In some examples, the first amplifying 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, wherein the non-inverting input terminal of the operational amplifier U2-A is connected to the third terminal of the selecting unit 121 through the circuit 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 terminal of the analog switch U11-A is connected to the other ends of the resistor R42, the resistor R23, and the resistor R24, respectively, and 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.

An ADC typically has an input range with optimal accuracy, and therefore the measured signal input to the ADC needs to fall within this range to obtain optimal measurement accuracy. For example, as shown in fig. 9, assuming that the optimal precision range of the ADC is 10 to 100mV, when the first conducting unit and the second conducting unit are conducting, that is, the primary switch circuit 210 is conducting, the ADC measures the sampling voltage on the first sampling unit, when the measured current is less than 0.1A, the sampling voltage on the first sampling unit will be less than 1mV, and not within the optimal precision range of the ADC, the MCU will control the analog switch U11-a, and select the resistor R23 to turn on as the negative feedback resistor of the operational amplifier U2-a, so that the measured value of the ADC is less than 10mV, and still not within the optimal precision range, the MCU will again control the analog switch U11-a, select the resistor R42 to turn on as the negative feedback resistor of the operational amplifier U2-a, so that the amplified voltage falls within the optimal precision range, the ADC can measure the measured value of the ADC to 100 times, and the current of the first sampling unit 122 is further calculated according to the measured value of the ADC to be less than 100 times.

For example, when the voltage read by the ADC is 100mV, the amplification factor of the first amplifying unit 122 is 100 times, and the resistance of the first sampling resistor is 0.01Ω, the measured current can be calculated to be 100 divided by 0.01, which is equal to 10A. Similarly, when the measured current is less than 1A but greater than 0.1A, the MCU configures the first amplifying unit 122 by a factor of 10; when the measured current is less than 10A but greater than 1A, the MCU configures the first amplifying unit 122 to have a multiple of 1. Therefore, a single sampling unit is provided with three measuring ranges, the wider current range can be accurately measured by using fewer sampling units, the circuit structure is simplified, and circuit components are simplified.

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

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

As shown in fig. 6, the source and the drain of the first conducting unit 211 and the second conducting unit 212 are respectively connected in positive and negative parallel, and then are integrated into the sampling circuit 110, so that the post-protection and sampling switch module 300 is effectively protected, and voltage clamping of the post-protection and sampling switch module 300 is realized.

For example, as shown in fig. 10, in the first re-protection, the parasitic diodes of the field effect transistor Q5 and the field effect transistor Q6 can bear the pulse current of 400A, and are directly connected in parallel to the subsequent circuit to be protected. When high-energy high-voltage input is carried out, high-energy current flows through the field effect transistor Q5 and the field effect transistor Q6 to clamp the voltage of a later-stage circuit, and meanwhile, the current far exceeds the fusing current of the fuse unit 400, so that the fuse unit 400 is fused quickly.

As shown in fig. 10, when the parasitic diodes in the fet Q5 and the fet Q6 are raised by the input current, the voltage generated by the input current is applied to the gates of the fet Q5 and the fet Q6 through the diode D3, the capacitor C2, the resistor R6, the resistor R7, or the diode D2, the capacitor C1, the resistor R8, and the resistor R9, so that the fet Q5 and the fet Q6 are turned on, and the resistances of the source and the drain are extremely small after the fet Q5 and the fet Q6 are turned on, so that the input current bypasses the fet Q5 and the fet Q6, and the bypass current is far beyond the fusing current of the fuse unit 400, so that the fuse unit 400 is quickly fused.

In the second protection, since the input current and voltage may be positive voltage, negative voltage or ac voltage, the field effect transistor Q5 and the field effect transistor Q6 are connected in positive and negative parallel and symmetrically designed with the diode D3, the capacitor C2, the resistor R6, the resistor R7 or the diode D2, the capacitor C1, the resistor R8 and the resistor R9, wherein the capacitor C1 and the capacitor C2 have the function of accelerating the conduction of the field effect transistor Q5 and the field effect transistor Q6.

In some examples, the input current monitoring circuit 220 includes a second amplifying unit 221, a converting unit 222, and a comparing unit 223 sequentially connected, the second amplifying unit 221 is connected to the third node c, and the comparing unit 223 is connected to the third terminal of the primary switching circuit 210.

As shown in fig. 10, the second amplifying unit 221 may include an operational amplifier U4-a, a resistor R39, a resistor R40, and a resistor R41, where the operational amplifier U4-a, the resistor R39, the resistor R40, and the resistor R41 together form a 100-amp, and samples and amplifies the total input current.

The conversion unit 222 may include operational amplifiers U4-D, U4-C, a resistor R33, a resistor R34, a resistor R35, a resistor R36, a resistor R37, a resistor R38, a diode D4, a diode D5, and a diode D6, and the conversion unit 222 receives the amplified signal of the total input current sample from the second amplification unit 221, and then obtains the absolute value of the current sample.

The comparing unit 223 may include an operational amplifier U4-B, and the comparing unit 223 compares the absolute value of the current sample outputted from the converting unit 222 with a voltage of 1.2V to form a detection of the input current. For example, when the input current is detected to be greater than 100mA, a high level is output, and the field effect transistor Q5 and the field effect transistor Q6 are controlled to be rapidly conducted and protect the subsequent circuit through the triode Q1 and the triode Q2.

In this way, the second amplifying unit 221, the converting unit 222 and the comparing unit 223 of the input current monitoring circuit 220 realize the third protection of the present device.

In some examples, the second stage switch circuit 310 includes a third conducting unit 311 and a fourth conducting unit 312, a first end of the third conducting unit 311 is connected to the input port a, a third end of the third conducting unit 311 is connected to the MCU, a first end of the fourth conducting unit 312 is connected to a second end of the third conducting unit 311 and to the access point s, a second end of the fourth conducting unit 312 is connected to the first end of the third conducting unit 311, and a third end of the fourth conducting unit 312 is connected to the MCU. The third conducting unit 311 is a field effect transistor Q11, the fourth conducting unit 312 is a field effect transistor 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 two ends of the fourth conducting unit 312 are sources, and the third end of the fourth conducting unit 312 is a gate.

As shown in fig. 11, the second stage switching circuit 310 may include a resistor R10, a resistor R12, a resistor R11, a resistor R13, a transistor Q7, a transistor Q8, a transistor Q9, a transistor Q10, a field effect transistor Q11, and a field effect transistor Q12.

For example, as shown in fig. 3, 8 and 10, after the field effect Q5 and the field effect transistor 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 resistor other than the resistor R25 is protected in parallel. Assuming that the measured current is 8mA, the sampling voltage on the resistor R25 is 0.01 multiplied by 8 and is equal to 0.08mV, at this time, the MCU configures the first amplifying unit 122 to amplify 100 times, and the amplified voltage is 8mV, which is smaller than the accuracy range of the ADC from 10 to 100mV. 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 applied to the base electrode of the triode Q7 through the resistor R10 to turn on the triode Q7, the base electrode of the low triode Q8 is connected to the base electrode of the triode Q8 through the fet Q12 after the triode Q7 is turned on, the triode Q8 is turned on to apply the high level to the G electrodes of the fet Q11 and the fet Q12, the fet Q11 and the fet Q12 are turned on, that is, the first two-stage switch circuit is turned on, the sampling circuit 110 (namely the resistor R25 and the resistor 20) connected in parallel with the first two-stage switch circuit is protected, meanwhile, the measured current flows through the resistor R25 and the resistor R20 to obtain a sampling voltage, and the sampling voltage is sent to the first amplifying unit 122 through the analog switch U1 and the resistor R21 to be measured by the ADC.

In the second stage I switching circuit 310, the transistor Q9 and the transistor Q10 form a voltage clamping protection circuit, and when the voltages at two ends of the transistor Q9 and the transistor Q10 are greater than 9V, the transistor Q9 and the transistor Q10 conduct soft breakdown, clamp the G-pole voltages of the field effect transistor Q11 and the field effect transistor Q12, and protect the field effect transistor Q11 and the field effect transistor Q12.

The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above is merely a preferred embodiment of the present application, and is not intended to limit the present application in any way. Any person skilled in the art may make many possible variations and modifications to the technical solution of the present application, or modify equivalent embodiments, using the methods and technical contents disclosed above, without departing from the scope of the technical solution of the present application. Therefore, all equivalent changes according to the shape, structure and principle of the present application are covered in the protection scope of the present application.

Claims (10)

1. An invasive current measurement apparatus, comprising:

the input sampling measurement module comprises an input port, a sampling circuit, a signal output circuit, a first node and a second node, wherein the input port is connected with the first node, the first end of the sampling circuit and the first end of the signal output circuit are connected with the first node, the second end of the sampling circuit and the second end of the signal output circuit are connected with the second node, and a plurality of access points are arranged on the sampling circuit;

the front-stage protection and sampling switch module comprises a first-stage switch circuit, an input current monitoring circuit and a third node, wherein a first end of the first-stage switch circuit is connected with the input port, a second end of the first-stage switch circuit and a first end of the input current detecting circuit are connected with the third node, a second end of the input current monitoring circuit is connected with the third end of the first-stage switch circuit, and the third node is connected with the second node;

the post-stage protection and sampling switch module comprises an I second-stage switch circuit, wherein a first end of the I second-stage switch circuit is connected with the input port, a second end of the I second-stage switch circuit is connected with an access point of the sampling circuit, I is more than or equal to 1, and I is an integer.

2. The invasive current measurement apparatus according to claim 1, wherein the sampling circuit comprises a first sampling unit and an nth sampling unit connected in sequence, the second end of the first sampling unit, the first end of the nth sampling unit being connected to the second node, the second end of the nth sampling unit being connected to the access point, the access point being connected to the first node, wherein N = i+1, N being an integer.

3. The invasive current measuring apparatus according to claim 1, wherein the signal output circuit comprises a selection unit and a first amplification unit, a first end of the selection unit is connected to the first node, a second end of the selection unit is connected to the second node, a first end of the first amplification unit is connected to a third end of the selection unit, and a second end of the first amplification unit is connected to the MCU.

4. An invasive current measuring apparatus according to claim 3, wherein the first amplifying unit comprises 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 selecting unit through the circuit R21, the output terminal of the operational amplifier U2-a is connected to the MCU through an ADC, one terminal 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 terminal of the resistor R22 is grounded, the input terminals of the analog switch U11-a are connected to the other terminals 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.

5. The invasive current measuring apparatus according to claim 1, wherein a safety unit is connected between the input port and the pre-protection and sampling switch module.

6. The invasive current measurement apparatus according to claim 1, wherein the primary switching circuit comprises a first conducting unit and a second conducting unit, a first end of the first conducting unit is connected to the input port, a third end of the first conducting unit is connected to the input current monitoring circuit, a first end of the second conducting unit is connected to a second end of the first conducting unit and to the third node, a second end of the second conducting unit is connected to the first end of the first conducting unit, and a third end of the second conducting unit is connected to the input current monitoring circuit.

7. The invasive current measuring apparatus according to claim 6, wherein the first conducting unit is a field effect transistor Q5, the second conducting unit is a field effect transistor Q6, a first end of the first conducting unit is a drain, a second end of the first conducting unit is a source, a third end of the first conducting unit is a gate, a first end of the second conducting unit is a drain, two ends of the second conducting unit are sources, and a third end of the second conducting unit is a gate.

8. The invasive current measuring apparatus according to claim 1, wherein 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 a third terminal of the primary switching circuit.

9. The invasive current measurement apparatus according to claim 1, wherein the I second stage switching circuit comprises a third conducting unit and a fourth conducting unit, a first end of the third conducting unit being connected to the input port, a third end of the third conducting unit being connected to the MCU, a first end of the fourth conducting unit being connected to a second end of the third conducting unit and to the access point, a second end of the fourth conducting unit being connected to the first end of the third conducting unit, a third end of the fourth conducting unit being connected to the MCU.

10. The invasive current measuring apparatus according to claim 1, wherein the third conducting unit is a field effect transistor Q11, the fourth conducting unit is a field effect transistor Q12, the first end of the third conducting unit is a drain, the second end of the third conducting unit is a source, the third end of the third conducting unit is a gate, the first end of the fourth conducting unit is a drain, the two ends of the fourth conducting unit are sources, and the third end of the fourth conducting unit is a gate.

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