Sampling circuit and sampling device

Abstract

The embodiment of the utility model provides a sampling circuit and a sampling device. The sampling circuit comprises an isolation power supply module, a bias power supply module, an amplification module and an isolation module, the isolation power supply module is used for isolating direct-current voltage input by a first power supply and outputting isolation voltage; the bias power supply module is used for outputting bias voltage based on the isolation voltage when receiving the isolation voltage; the amplification module is used for collecting the positive voltage and the negative voltage of the to-be-tested device when receiving the isolation voltage and the bias voltage, and amplifying the differential voltage between the positive voltage and the negative voltage to output an amplified voltage. The isolation module is used for isolating the amplified voltage when receiving the amplified voltage and outputting the sampling voltage to the control device. While current sampling is carried out on the to-be-tested equipment, the possibility that the low-voltage side control equipment is damaged by faults such as high voltage and large current on the high-voltage side is effectively reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power electronics, and particularly relates to a sampling circuit and a sampling device. BACKGROUND

[0002] With the development of science and technology, the fields of electric vehicles and new energy storage are rapidly rising, and the importance of current detection is self-evident. In the application of energy storage and charging piles, high-precision and high-isolation current sampling is crucial for timely control of current output.

[0003] In the prior art, the integrated chip is widely used to detect current sampling. However, the structure of the integrated chip detection method is complex, which leads to a high failure rate of detection and greatly increases the cost. The integrated chip method generally has low isolation level and the creepage distance cannot meet the requirements of high-voltage platforms. CONTENT OF THE INVENTION

[0004] The application embodiment provides a sampling circuit and a sampling device, which effectively reduces the possibility of damage to low-voltage side control equipment caused by high-voltage and large-current faults on the high-voltage side while sampling the current of the device to be measured.

[0005] In a first aspect, the application embodiment provides a sampling circuit, which comprises an isolation power supply module, a bias power supply module, an amplification module and an isolation module. The isolation power supply module is connected with the bias power supply module, the amplification module and a first power supply, respectively. The bias power supply module is also connected with the amplification module. The amplification module is connected with the isolation module and a device to be measured, respectively. The isolation module is also connected with a control device. The isolation power supply module is used to isolate and output an isolation voltage from a direct current voltage input by the first power supply. The direct current voltage and the isolation voltage are not in common ground. The bias power supply module is used to output a bias voltage based on the isolation voltage when the isolation voltage is received. The bias voltage and the isolation voltage are in common ground. The amplification module is used to collect a positive voltage and a negative voltage of the device to be measured when the isolation voltage and the bias voltage are received, and amplify a differential voltage between the positive voltage and the negative voltage to output an amplified voltage. The amplified voltage and the isolation voltage are in common ground. The isolation module is used to isolate the amplified voltage when the amplified voltage is received, and output a sampling voltage to the control device. The sampling voltage and the direct current voltage are in common ground.

[0006] In some embodiments, the isolation power module comprises a drive chip U1, a transformer T1, a rectifier chip U2; the 5-pin of the drive chip U1 is connected with the first power supply, the 2-pin of the drive chip U1 is connected with the first ground, the 6-pin of the drive chip U1 is connected with the first input end of the transformer T1, the 4-pin of the drive chip U1 is connected with the second input end of the transformer T1, the first output end of the transformer T1 is connected with the 4-pin of the rectifier chip U2, the second input end of the transformer T1 is connected with the 5-pin of the rectifier chip U2, the 3-pin of the rectifier chip U2 is connected with the bias power module, the amplification module and the isolation module respectively, the 1-pin and the 2-pin of the rectifier chip U2 are both connected with the second ground; wherein the 3-pin of the rectifier chip U2 is used for outputting the isolation voltage.

[0007] In some embodiments, the bias power module comprises a resistor R14, a resistor R15, a resistor R16, a voltage reference source U3, a capacitor C14; the first end of the resistor R14 is connected with the isolation power module, the second end of the resistor R14 is connected with the first end of the resistor R15, the first end of the voltage reference source U3, the first end of the capacitor C14 and the amplification module respectively, the second end of the resistor R15 is connected with the first end of the resistor R16 and the second end of the voltage reference source U3, the second end of the resistor R16, the third end of the voltage reference source U3 and the second end of the capacitor C14 are connected and all are connected with the second ground; wherein the second end of the resistor R14 is used for outputting the bias voltage.

[0008] In some embodiments, the amplification module comprises a resistor R19, a resistor R24, a capacitor C19, a capacitor C20, a capacitor C21, a monitoring chip U4; the first end of the resistor R19 is connected with the positive electrode of the device to be tested, the first end of the resistor R24 is connected with the negative electrode of the device to be tested, the 3-pin of the monitoring chip U4 is connected with the second end of the resistor R19 and the first end of the capacitor C19, the 4-pin of the monitoring chip U4 is connected with the second end of the resistor R24 and the first end of the capacitor C20, the second end of the capacitor C19 and the second end of the capacitor C20 are both connected with the second ground, the 2-pin of the monitoring chip U4 is connected with the second ground, the 5-pin of the monitoring chip U4 is connected with the bias power module, the 6-pin of the monitoring chip U4 is connected with the first end of the capacitor C21 and the isolation power module, the second end of the capacitor C21 is connected with the second ground, the 1-pin of the monitoring chip U4 is connected with the isolation module; wherein the 1-pin of the monitoring chip U4 is used for outputting the amplification voltage.

[0009] In some embodiments, the amplification module further comprises a resistor R18, a resistor R23, a magnetic bead L5, a magnetic bead L6, a bidirectional TVS D5, a bidirectional TVS D6; the first end of the resistor R18 is connected with the positive electrode of the device to be tested, the second end of the resistor R18 is connected with the second end of the bidirectional TVS D5 and the first end of the magnetic bead L5, the first end of the bidirectional TVS D5 is connected with the second ground, the second end of the magnetic bead L5 is connected with the first end of the resistor R19, the first end of the resistor R23 is connected with the negative electrode of the device to be tested, the second end of the resistor R23 is connected with the second end of the bidirectional TVS D6 and the first end of the magnetic bead L6, the first end of the bidirectional TVS D6 is connected with the second ground, and the second end of the magnetic bead L6 is connected with the first end of the resistor R24.

[0010] In some embodiments, the isolation module comprises a first operational amplifier unit, an isolation unit, and a second operational amplifier unit; the first operational amplifier unit is connected with the amplification module, the isolation unit is connected with the first operational amplifier unit, the second operational amplifier unit, and the isolation power supply module respectively, and the second operational amplifier unit is further connected with the first power supply and the control device; the first operational amplifier unit is used to output a first voltage when receiving the amplification voltage; wherein the first voltage and the isolation voltage share the same ground; the isolation unit is used to isolate the amplification voltage and output an amplified isolation voltage when receiving the first voltage; wherein the amplified isolation voltage shares the same ground with the direct current voltage; and the second operational amplifier unit is used to output the sampling voltage based on the amplified isolation voltage when receiving the amplified isolation voltage.

[0011] In some embodiments, the first operational amplifier unit comprises an operational amplifier U8A, a resistor R20, a resistor R21, a capacitor C15, and a capacitor C16; the first end of the resistor R20 is connected with the amplification module, the second end of the resistor R20 is connected with the inverting input terminal of the operational amplifier U8A, the first end of the capacitor C15, and the isolation unit, the non-inverting input terminal of the operational amplifier U8A is connected with the second ground, the output terminal of the operational amplifier U8A is connected with the second end of the capacitor C15 and the first end of the resistor R21, the second end of the resistor R15 is connected with the isolation unit, the 8-pin of the operational amplifier U8A is connected with the first end of the capacitor C16 and the isolation power supply module, the second end of the capacitor C16 is connected with the second ground, the 4-pin of the operational amplifier U8A is connected with the second ground, and the second end of the resistor R21 is used to output the first voltage.

[0012] In some embodiments, the isolation unit includes a capacitor C18 and an optocoupler P1; pin 1 of the optocoupler P1 is connected to the first op amp unit, pin 2 of the optocoupler P1 is connected to the first end of the capacitor C18 and the isolated power supply module, the second end of the capacitor C18 is connected to the second ground, pin 3 of the optocoupler P1 is connected to the first op amp unit, pin 4 of the optocoupler P1 is connected to the second ground, pin 5 of the optocoupler P1 is connected to the second op amp unit and to the first ground, and pin 6 of the optocoupler P1 is connected to the second op amp unit.

[0013] In some embodiments, the second operational amplifier unit includes an operational amplifier U5A, a resistor R17, a resistor R22, a capacitor C17, and a dual-series diode D4; the inverting input terminal of the operational amplifier U5A is connected to the first end of the resistor R17 and the isolation unit, the non-inverting input terminal of the operational amplifier U5A is connected to the isolation unit and to the first ground, the output terminal of the operational amplifier U5A is connected to the second end of the resistor R17 and the first end of the resistor R22, pin 8 of the operational amplifier U5A is connected to the first end of the capacitor C17 and the first power supply, the second end of the capacitor C17 is connected to the first ground, pin 4 of the operational amplifier U5A is connected to the first ground, the second end of the resistor R22 is connected to the third end of the dual-series diode D4 and the control device, the second end of the dual-series diode D4 is connected to the second power supply, and the first end of the dual-series diode D4 is connected to the first ground; wherein, the second end of the resistor R22 is used to output the sampling voltage.

[0014] In a second aspect, an embodiment of the present application provides a sampling device, which includes the sampling circuit as described above.

[0015] Different from the related technical solutions, the embodiment of the application provides a sampling circuit and a sampling device, the sampling circuit comprises an isolation power supply module, a bias power supply module, an amplification module and an isolation module; the isolation power supply module is connected with the bias power supply module, the amplification module and a first power supply respectively, the bias power supply module is also connected with the amplification module, the amplification module is connected with the isolation module and a device under test respectively, and the isolation module is also connected with a control device; the isolation power supply module is used for isolating a direct current voltage input by the first power supply and outputting an isolation voltage; wherein the direct current voltage and the isolation voltage are not common; the bias power supply module is used for outputting a bias voltage based on the isolation voltage when the isolation voltage is received; wherein the bias voltage and the isolation voltage are common; the amplification module is used for collecting a positive voltage and a negative voltage of the device under test when the isolation voltage and the bias voltage are received, amplifying a differential voltage between the positive voltage and the negative voltage to output an amplified voltage; wherein the amplified voltage and the isolation voltage are common; and the isolation module is used for isolating the amplified voltage when the amplified voltage is received, and outputting a sampling voltage to the control device; wherein the sampling voltage and the direct current voltage are common. The embodiment of the application can realize detection of the current of the device under test, can not only sample with high precision, but also well isolate high-voltage measurement and low-voltage measurement. And by adopting the bias power supply mode, bidirectional current sampling is supported, when the reverse current, the differential voltage between the two ends of the device under test is a negative voltage, and by the bias power supply, the output can always be positive. The possibility of damage of the low-voltage side control device by high voltage and large current faults on the high-voltage side is effectively reduced. BRIEF DESCRIPTION OF DRAWINGS

[0016] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, which are schematic and not drawn to scale, wherein like references indicate similar elements, and in which:

[0017] Figure 1 is a structural block diagram of the sampling circuit provided by the embodiment of the application;

[0018] Figure 2 is a structural block diagram of the isolation module provided by the embodiment of the application;

[0019] Figure 3 is a circuit structure schematic diagram of the isolation power supply module provided by the embodiment of the application;

[0020] Figure 4 is a circuit structure schematic diagram of the bias power supply module provided by the embodiment of the application;

[0021] Figure 5is a circuit structure schematic diagram of an amplification module provided by an embodiment of the present application.

[0022] Figure 6 is a circuit structure schematic diagram of an isolation module provided by an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and in detail below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0024] The technical features involved in the various embodiments of the present application described below can be combined with each other without conflict.

[0025] When an element is described as "connected to" another element, it can be directly connected to the other element, or one or more intermediate elements can be present therebetween.

[0026] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than that illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of a kind and do not limit the number of objects, for example, the first object can be one or more.

[0027] Please refer to Figure 1 , Figure 1 is a structure block diagram of a sampling circuit 100 provided by an embodiment of the present application.

[0028] An embodiment of the present application provides a sampling circuit 100, which comprises an isolation power supply module 10, a bias power supply module 20, an amplification module 30 and an isolation module 40.

[0029] The isolation power supply module 10 is connected with the bias power supply module 20, the amplification module 30 and a first power supply 400 respectively, the bias power supply module 20 is further connected with the amplification module 30, the amplification module 30 is connected with the isolation module 40 and a device under test 200 respectively, and the isolation module 40 is further connected with a control device 300.

[0030] Specifically, the isolation power module 10 is configured to isolate the direct current voltage input by the first power supply 400 and output an isolated voltage; wherein the direct current voltage and the isolated voltage are not common. The bias power module 20 is configured to output a bias voltage based on the isolated voltage when receiving the isolated voltage; wherein the bias voltage and the isolated voltage are common. The amplification module 30 is configured to collect the positive voltage and the negative voltage of the device under test 200 when receiving the isolated voltage and the bias voltage, and amplify the differential voltage between the positive voltage and the negative voltage to output an amplified voltage; wherein the amplified voltage and the isolated voltage are common. The isolation module 40 is configured to isolate the amplified voltage when receiving the amplified voltage, and output a sampling voltage to the control device 300; wherein the sampling voltage and the direct current voltage are common.

[0031] The device under test 200 can be a shunt, which is a device used to measure current. When current passes through the shunt, a voltage drop is generated across the shunt. This voltage drop is proportional to the size of the current passing through, and by measuring this voltage drop, the value of the current can be calculated.

[0032] The control device 300 can be an MCU (Microcontroller Unit). In this sampling circuit, the MCU serves as a control device and receives the sampling voltage output from the isolation module. The MCU can use this sampling voltage to perform data processing according to a pre-written program. For example, the sampling voltage can be converted into a corresponding current value (if the device under test is a shunt), and then further operations can be performed, such as comparing the current value with a pre-set threshold value, controlling other related circuit elements (such as cutting off the circuit when the current is too large) according to the comparison result, or storing and displaying the current data.

[0033] In actual application, first, the first power supply 400 outputs a direct current voltage into the isolation power module 10. The isolation power module 10 uses electromagnetic isolation or optoelectronic isolation technology (for example, through a transformer or an optocoupler device) to isolate the direct current voltage. The purpose of isolation is to cut off the electrical connection between the input direct current power supply and the subsequent circuit, avoiding common ground interference and noise conduction. After isolation, an isolated voltage is output, and at this time the isolated voltage and the direct current voltage of the first power supply 400 are not common, forming a relatively independent power supply output, which provides a safe power supply environment for subsequent modules.

[0034] The bias power module 20 receives the isolation voltage output by the isolation power module 10. Based on the isolation voltage, the bias voltage is output through the internal circuit structure (such as using resistance voltage division, voltage stabilizing diode, etc.). The bias voltage is common with the isolation voltage, and this bias voltage is mainly used to provide a suitable bias operating point for the amplification module 30. For example, in the amplification circuit, a suitable bias voltage can ensure that the transistor and other amplification elements work in the appropriate linear amplification region, avoiding signal distortion.

[0035] The amplification module 30 simultaneously receives the isolation voltage output by the isolation power module 10 and the bias voltage output by the bias power module 20. With the support of the two voltages, the amplification module 30 starts to collect the positive voltage and the negative voltage of the device under test 200 (such as a shunt). When there is a difference between the positive voltage and the negative voltage, the differential amplification circuit will amplify the differential voltage and output an amplified voltage. The amplified voltage is common with the isolation voltage, providing a suitable signal level for the subsequent isolation module.

[0036] The isolation module 40 receives the amplified voltage output by the amplification module 30. The isolation module 40 also uses isolation technology (such as optocoupler or transformer coupling) to isolate the amplified voltage. The purpose of isolation is to further cut off the electrical connection in the signal transmission path, prevent the amplified signal from being disturbed by external interference, and also avoid the isolation side circuit of the amplification module 30 causing electrical interference to the control device 300 (such as MCU). After isolation, the sampling voltage is output, and at this time the sampling voltage is common with the direct current voltage of the first power supply 400, so that the sampling voltage can be well compatible with the power supply system of the control device 300, facilitating the control device 300 to process and analyze the sampling voltage, thereby realizing accurate sampling of the related parameters (such as measuring current through the shunt) of the device under test 200.

[0037] Please refer to Figure 2 , Figure 2 is a structural block diagram of the isolation module 40 provided by the embodiment of the application.

[0038] In some embodiments, the isolation module 40 includes a first operational amplifier unit 41, an isolation unit 42, and a second operational amplifier unit 43.

[0039] The first operational amplifier unit 41 is connected with the amplification module 30, the isolation unit 42 is connected with the first operational amplifier unit 41, the second operational amplifier unit 43, and the isolation power module 10 respectively, and the second operational amplifier unit 43 is further connected with the first power supply 400 and the control device 300.

[0040] Specifically, the first operational amplifier unit 41 is configured to output a first voltage when receiving an amplified voltage, wherein the first voltage is common with an isolated voltage. The isolation unit 42 is configured to isolate the amplified voltage and output an amplified isolated voltage when receiving the first voltage, wherein the amplified isolated voltage is common with a direct current voltage. The second operational amplifier unit 43 is configured to output a sampling voltage based on the amplified isolated voltage when receiving the amplified isolated voltage.

[0041] In the embodiment, first, when the first operational amplifier unit 41 receives the amplified voltage output by the amplification module 30, it starts to work as a pre-stage of signal conditioning. The first operational amplifier unit 41 buffers or simply amplifies the amplified voltage, and outputs a first voltage. Since the first voltage is common with the isolated voltage, the reference ground of the first voltage is consistent with the isolated voltage output by the isolated power supply module 10, thereby providing a suitable signal level basis for the subsequent isolation unit.

[0042] After receiving the first voltage, the isolation unit 42 processes the amplified voltage through isolation technology. If it is optoelectronic isolation, there will be a light-emitting diode and a photosensitive element inside. When the amplified voltage acts on the light-emitting diode, the light-emitting intensity of the light-emitting diode will change with the amplified voltage, and the photosensitive element receives the light signal and converts it into an electrical signal, thereby achieving electrical isolation.

[0043] After receiving the amplified isolated voltage, the second operational amplifier unit 43 again uses the characteristics of the operational amplifier to condition the signal. It can further amplify, filter, or level convert the amplified isolated voltage. For example, according to the input requirements of the control device 300 (such as an MCU), the amplified isolated voltage is adjusted to a suitable voltage range, and finally a sampling voltage is output. The sampling voltage can be accurately received and processed by the control device 300, and used to analyze the parameters of the device under test 200. For example, if the device under test 200 is a shunt, the current size and other related parameters can be calculated by processing the sampling voltage.

[0044] Please refer to Figure 3 , Figure 3 is a circuit structure schematic diagram of the isolated power supply module 10 provided in the embodiment.

[0045] In some embodiments, the isolated power supply module 10 includes a driving chip U1, a transformer T1, and a rectifier chip U2.

[0046] The 5th pin of the driving chip U1 is connected with the first power supply 400, the 2nd pin of the driving chip U1 is connected with the first ground GND, the 6th pin of the driving chip U1 is connected with the first input end of the transformer T1, the 4th pin of the driving chip U1 is connected with the second input end of the transformer T1, the first output end of the transformer T1 is connected with the 4th pin of the rectifier chip U2, the second input end of the transformer T1 is connected with the 5th pin of the rectifier chip U2, the 3rd pin of the rectifier chip U2 is connected with the bias power supply module 20, the amplification module 30 and the isolation module 40 respectively, and the 1st pin and the 2nd pin of the rectifier chip U2 are connected with the second ground CHG-; the 3rd pin of the rectifier chip U2 is used for outputting an isolation voltage.

[0047] In some embodiments, the isolation power supply module 10 further comprises a capacitor C22, a capacitor C23 and a capacitor C24. The first end of the capacitor C22 is connected with the 5th pin of the driving chip U1, the second end of the capacitor C22 is connected with the 2nd pin of the driving chip U1, the capacitor C23 is connected with the capacitor C22 in parallel, the first end of the capacitor C24 is connected with the 3rd pin of the rectifier chip U2, and the second end of the capacitor C24 is connected with the 1st pin of the rectifier chip U2.

[0048] Specifically, since the shunt is connected with the high-voltage output side in the system, the isolation power supply module 10 is needed to isolate the first power supply 400 (for example, a 5V DC power supply) to meet the power supply of the subsequent bias power supply module 20 and the amplification module 30. The capacitor C22 and the capacitor C23 are input filter capacitors, which filter out the interference in the DC voltage input by the first power supply 400. The capacitor C24 is an output filter capacitor, which filters out the interference in the output isolation voltage. The isolation transformer T1 meets the isolation level of 5000VAC. The isolation power supply driving chip U1, the transformer T1 and the bridge rectifier chip U2 are used in combination, so that the output and the input have a high isolation of 5000VAC, and the output is used for power supply of other high-voltage measurement chips.

[0049] It should be noted that the isolation power supply module 10 is not limited to transformer isolation, and an integrated isolation power supply module can also be used as long as the isolation level meets the requirement.

[0050] Please refer to Figure 4 , Figure 4 is a circuit structure schematic diagram of the bias power supply module 20 provided by the embodiment of the present application.

[0051] In some embodiments, the bias power supply module 20 comprises a resistor R14, a resistor R15, a resistor R16, a voltage reference source U3 and a capacitor C14.

[0052] The first end of the resistor R14 is connected with the isolation power supply module 10, the second end of the resistor R14 is connected with the first end of the resistor R15, the first end of the voltage reference source U3, the first end of the capacitor C14 and the amplification module 30 respectively, the second end of the resistor R15 is connected with the first end of the resistor R16 and the second end of the voltage reference source U3, the second end of the resistor R16, the third end of the voltage reference source U3 and the second end of the capacitor C14 are connected and all connected with the second ground CHG-; wherein the second end of the resistor R14 is used for outputting the bias voltage.

[0053] Specifically, the resistor R14 is a current limiting resistor, which prevents the output current from exceeding the rated output current of the voltage reference source U3. The capacitor C14 is a filter capacitor, which filters the interference of the output bias voltage. The resistors R15 and R16 and the voltage reference source determine the voltage value of the output bias voltage. For example, if the voltage of the voltage reference source U3 is 1.24V, the calculation formula is bias voltage = 1.24*(R15 / R16+1), wherein R15 represents the resistance value of the resistor R15 and R16 represents the resistance value of the resistor R16.

[0054] It should be noted that the bias power supply module 20 is not limited to the circuit composed of the voltage reference source U3, but can also be an LDO (Low-Dropout Regulator, low dropout regulator), a resistor voltage divider and the like.

[0055] Please refer to Figure 5 , Figure 5 is a circuit structure schematic diagram of the amplification module 30 provided by the embodiment of the application.

[0056] In some embodiments, the amplification module 30 includes a resistor R19, a resistor R24, a capacitor C19, a capacitor C20, a capacitor C21 and a monitoring chip U4.

[0057] The first end of the resistor R19 is connected with the positive electrode of the device under test 200, the first end of the resistor R24 is connected with the negative electrode of the device under test 200, the second end of the resistor R19 and the first end of the capacitor C19 are connected with the 3-pin of the monitoring chip U4, the second end of the resistor R24 and the first end of the capacitor C20 are connected with the 4-pin of the monitoring chip U4, the second end of the capacitor C19 and the second end of the capacitor C20 are both connected with the second ground CHG-, the 2-pin of the monitoring chip U4 is connected with the second ground CHG-, the 5-pin of the monitoring chip U4 is connected with the bias power supply module 20, the first end of the capacitor C21 and the isolation power supply module 10 are connected with the 6-pin of the monitoring chip U4, the second end of the capacitor C21 is connected with the second ground CHG-, and the 1-pin of the monitoring chip U4 is connected with the isolation module 40; wherein the 1-pin of the monitoring chip U4 is used for outputting the amplification voltage.

[0058] In some embodiments, the amplification module 30 further comprises a resistor R18, a resistor R23, a magnetic bead L5, a magnetic bead L6, a bidirectional TVS D5, a bidirectional TVS D6.

[0059] The first end of the resistor R18 is connected with the positive pole of the device under test 200, the second end of the resistor R18 is connected with the second end of the bidirectional TVS D5 and the first end of the magnetic bead L5, the first end of the bidirectional TVS D5 is connected with the second ground CHG-, the second end of the magnetic bead L5 is connected with the first end of the resistor R19, the first end of the resistor R23 is connected with the negative pole of the device under test 200, the second end of the resistor R23 is connected with the second end of the bidirectional TVS D6 and the first end of the magnetic bead L6, the first end of the bidirectional TVS D6 is connected with the second ground CHG-, and the second end of the magnetic bead L6 is connected with the first end of the resistor R24.

[0060] The monitoring chip U4 has a fixed gain amplification. For example, the amplification multiple can be 20 times. The resistors R18 and R23 are input current limiting resistors, which play a role in current limiting. The magnetic beads L5 and L6 and the bidirectional TVS D5 and D6 can effectively prevent the influence of ESD. The resistors R19 and R24 and the capacitors C19 and C20 are matched to form two groups of RC filters, which can effectively filter out interference and ensure the cleanliness and accuracy of the input signal.

[0061] Please refer to Figure 6 , Figure 6 The circuit structure diagram of the isolation module 40 provided by the embodiments of the present application is shown in FIG. 4.

[0062] In some embodiments, the first operational amplifier unit 41 comprises an operational amplifier U8A, a resistor R20, a resistor R21, a capacitor C15, and a capacitor C16.

[0063] The first end of the resistor R20 is connected with the amplification module 30, the second end of the resistor R20 is connected with the inverting input end of the operational amplifier U8A, the first end of the capacitor C15, and the isolation unit 42, the non-inverting input end of the operational amplifier U8A is connected with the second ground CHG-, the output end of the operational amplifier U8A is connected with the second end of the capacitor C15 and the first end of the resistor R21, the second end of the resistor R15 is connected with the isolation unit 42, the 8 pin of the operational amplifier U8A is connected with the first end of the capacitor C16 and the isolation power supply module 10, the second end of the capacitor C16 is connected with the second ground CHG-, the 4 pin of the operational amplifier U8A is connected with the second ground CHG-, and the second end of the resistor R21 is used for outputting the first voltage.

[0064] In some embodiments, the isolation unit 42 comprises a capacitor C18 and an optical coupler P1.

[0065] Among them, pin 1 of the optocoupler P1 is connected to the first operational amplifier unit 41, pin 2 of the optocoupler P1 is connected to the first end of the capacitor C18 and the isolated power supply module 10, the second end of the capacitor C18 is connected to the second ground CHG-, pin 3 of the optocoupler P1 is connected to the first operational amplifier unit 41, pin 4 of the optocoupler P1 is connected to the second ground CHG-, pin 5 of the optocoupler P1 is connected to the second operational amplifier unit 43 and to the first ground GND, and pin 6 of the optocoupler P1 is connected to the second operational amplifier unit 43.

[0066] In some embodiments, the second operational amplifier unit 43 includes an operational amplifier U5A, a resistor R17 , a resistor R22 , a capacitor C17 , and a dual series diode D4 .

[0067] Among them, the inverting input terminal of the operational amplifier U5A is connected to the first end of the resistor R17 and the isolation unit 42, the non-inverting input terminal of the operational amplifier U5A is connected to the isolation unit 42 and to the first ground GND, the output terminal of the operational amplifier U5A is connected to the second end of the resistor R17 and the first end of the resistor R22, the 8th pin of the operational amplifier U5A is connected to the first end of the capacitor C17 and the first power supply 400, the second end of the capacitor C17 is connected to the first ground GND, the 4th pin of the operational amplifier U5A is connected to the first ground GND, the second end of the resistor R22 is connected to the third end of the dual-series diode D4 and the control device 300, the second end of the dual-series diode D4 is connected to the second power supply, and the first end of the dual-series diode D4 is connected to the first ground GND; wherein, the second end of the resistor R22 is used to output the sampling voltage.

[0068] The following combination Figure 5 and Figure 6 The working principle of the sampling circuit 100 is briefly described.

[0069] like Figure 5 As shown, under normal conditions, the input port IS+ of this embodiment is connected to the positive electrode of the device under test 200 (e.g., a shunt), and the input port IS- is connected to the negative electrode of the device under test 200. When current flows through, a small voltage signal will exist at both ends of the shunt, so a differential voltage Vi (between -75mV and 75mV) is formed at both ends of IS+ and IS-. The differential voltage Vi passes through the current limiting resistors R18 and R23, and is filtered by two sets of RC circuits before flowing into the two IN pins (pins 3 and 4) of the monitoring chip U4. The internal fixed gain of the chip can be 20, and due to the bias voltage ( Figure 5 VREF_1.65V in the voltage regulator is connected to the REF pin (pin 5) of the power monitoring chip U4, so the amplified voltage output by the OUT pin (pin 1) of the monitoring chip U4 is V1=20Vi+1.65, where Vi is the differential voltage between the positive and negative voltages of the device under test 200.

[0070] As shown in Figure 6 theoretically, when the OUT pin (1 pin) of the monitoring chip U4 outputs an amplified voltage, the capacitor C15 charges with time, and the voltage of the output pin (1 pin) of the operational amplifier U8A decreases linearly, and finally decreases to: - the voltage output by the OUT pin (1 pin) of the monitoring chip U4, that is: - (20Vi + 1.65). However, in practice, since the 3 pin and the 4 pin of the operational amplifier U8A are connected to the second ground CHG-, which is not a negative voltage, the voltage of the output pin (1 pin) of the operational amplifier U8A can only be 0V (i.e. the first voltage). At this time, the signal at 5V_CHG (i.e. the isolation voltage) flows into the LED (2 pin) and out of the LED (1 pin) of the high-isolation linear optocoupler P1, and then flows to the output pin (1 pin) of the operational amplifier U8A through the current-limiting resistor R21, and the current is 5 / R21, where R21 is the resistance value of the resistor R21. (It is worth noting that the value of the resistor R21 should be determined according to the working current that the LED of the high-isolation linear optocoupler P1 can withstand) At this time, since the LED (between 1 pin and 2 pin) inside the high-isolation linear optocoupler P1 has current passing through, the LED starts to work and emit light, so that the input photodiode (between 3 pin and 4 pin) inside the high-isolation linear optocoupler P1 and the output photodiode (between 5 pin and 6 pin) inside the high-isolation linear optocoupler P1 start to work.

[0071] Specifically, the input photodiode (between 3 pin and 4 pin) inside the high-isolation linear optocoupler P1 starts to work, and the current IPD1 flows from the OUT pin (1 pin) of the monitoring chip U4, through the resistor R20, into the 3 pin of the high-isolation linear optocoupler P1, and then out of the 4 pin to the second ground CHG-. The current IPD1 = (20Vi + 1.65) / R20, where Vi is the differential voltage between the positive voltage and the negative voltage of the device to be tested 200, and R20 is the resistance value of the resistor R20.

[0072] The output photodiode (between 5 pin and 6 pin) inside the high-isolation linear optocoupler P1 starts to work, and the current IPD2 flows from the OUT pin (1 pin) of the operational amplifier U5A (the output is Vo), through the resistor R17, into the 6 pin of the high-isolation linear optocoupler P1, and then out of the 5 pin to GND. The current IPD2 = Vo / R17, where Vo is the voltage at the point Vo, and R17 is the resistance value of the resistor R17. Figure 6

[0073] ​The current IPD1 of the internal input photodiode (i.e., between pins 3 and 4) of the high-isolation linear optocoupler P1 and the current IPD2 of the output photodiode (i.e., between pins 5 and 6) have a relationship of IPD1 / IPD2=K, and the K value is the fixed gain of the device. If the K value of the high-isolation linear optocoupler P1 used in the embodiment of the present invention is 1, then the relationship IPD1 / IPD2=1 exists, that is, (20Vi+1.65) / R20=Vo / R17, so Vo=(20Vi+1.65)R17 / R20. Finally, Vo flows into the control device 300 (e.g., MCU) through the current limiting resistor R22 and the dual-series diode D4, completing the current detection. It is worth noting that the dual-series diode D4 here is to prevent the Vo output from being too high and exceeding the sampling voltage that the MCU can withstand, thereby playing a clamping role.

[0074] The sampling circuit 100 provided in the embodiment of the present application has the following beneficial effects:

[0075] First, the shunt current is detected using a current sensing chip, a high-isolation linear optocoupler, and an isolated power supply. The current sensing chip accurately acquires the current-related voltage signal. The high-isolation linear optocoupler ensures signal accuracy and provides excellent isolation during signal transmission. The isolated power supply provides stable, interference-free power support for the entire detection process. The coordinated operation of these components enables the sampling circuit to detect the shunt current with high precision.

[0076] Secondly, the isolated power supply module isolates the DC voltage input by the first power supply and outputs an isolated voltage so that the DC voltage and the isolated voltage do not share the same ground. This isolation method cuts off the electrical connection between the high-voltage side (the side of the device under test where high voltage may exist) and the low-voltage side (the control device side) at the power supply level, effectively preventing high voltage, high current and other faults on the high-voltage side from damaging the control device on the low-voltage side. After receiving the amplified voltage, the isolation module isolates again and outputs a sampling voltage that shares the same ground as the DC voltage. These two layers of isolation measures ensure good isolation between high-voltage and low-voltage measurements, can meet the isolation requirements of the 1000V platform (isolation can reach 5000V), and ensure the safe and stable operation of the control equipment in a high-voltage environment.

[0077] Third, the bias power module outputs a bias voltage after receiving the isolation voltage, and this bias voltage shares a common ground with the isolation voltage. When reverse current flows, the voltage across the shunt is negative, but the bias power supply ensures that the output remains positive. This feature enables the sampling circuit to accurately detect bidirectional currents, greatly expanding the circuit's application range. For example, it is very useful in circuits that need to detect frequent changes in current direction, such as current feedback in motor control and battery charge and discharge current detection.

[0078] In the fourth aspect, the magnetic beads and the TVS tube are used for ESD protection. The magnetic beads can suppress high-frequency noise and electromagnetic interference. When high-frequency signals generated by electrostatic discharge occur, the magnetic beads can consume the high-frequency energy, thereby reducing the influence on the circuit. The TVS tube (transient voltage suppressor) can quickly conduct when a high-voltage pulse generated by electrostatic discharge occurs, and clamp the voltage in a safe range, thereby protecting the internal circuit from damage. This protection method is low in cost, and can effectively protect the internal circuit without significantly increasing the cost and complexity of the circuit.

[0079] In the fourth aspect, the overall circuit structure is relatively simple, and high-precision sampling, high-isolation, bidirectional current detection, and ESD protection can be achieved without complex circuit architecture and a large number of expensive elements. The simple circuit is easy to design and maintain, and is low in cost. The performance requirements are met, and the cost of the product is reduced, thereby improving the market competitiveness of the product.

[0080] In the fifth aspect, through various means such as isolation measures and ESD protection, the circuit can safely operate in a high-voltage environment, and can stably sample the current and output a reliable sampling voltage to the control device. This safety and reliability enables the sampling circuit to be applied to various electrical systems with high safety and stability requirements, such as industrial automation and power electronic devices.

[0081] In summary, the sampling circuit 100 provided by the embodiments of the present application uses a current detection chip, a high-isolation linear optocoupler, and an isolated power supply to detect the shunt current. The sampling circuit 100 can not only sample with high precision, but also effectively isolate high-voltage measurement from low-voltage measurement, thereby meeting the isolation requirement of a 1000V platform (isolation up to 5000V). By using a bias power supply, bidirectional current sampling is supported. When the reverse current occurs, the two ends of the shunt (i.e., IS+ and IS- connected to the board) are negative voltages. By using the bias power supply, the output can always be positive. In addition, the magnetic beads and the TVS tube are used for ESD protection, which is low in cost and can effectively protect the internal circuit. Overall, the circuit is relatively simple and low in cost, and is relatively safe and reliable.

[0082] The embodiments of the present application also provide a sampling device, which includes the sampling circuit 100 as described above.

[0083] The circuit structure and working principle of the sampling circuit 100 can refer to the above-described embodiments, which will not be described here again.

[0084] Finally, it should be noted that: the above examples are used to illustrate the technical solutions of the present application, rather than limiting them; under the idea of the present application, the technical features in the above examples or different examples can also be combined, and there are many other changes of different aspects of the present application as described above, in order to be simple, they are not provided in details; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of each embodiment of the present application.

Claims

1. A sampling circuit, characterized in that: The sampling circuit includes an isolation power supply module, a bias power supply module, an amplification module, and an isolation module; The isolation power supply module is respectively connected to the bias power supply module, the amplification module and the first power supply, the bias power supply module is also connected to the amplification module, the amplification module is respectively connected to the isolation module and the device under test, and the isolation module is also connected to the control device; The isolated power supply module is used to isolate the DC voltage input by the first power supply and output an isolated voltage; wherein the DC voltage and the isolated voltage do not share a common ground; The bias power supply module is configured to output a bias voltage based on the isolation voltage when receiving the isolation voltage; wherein the bias voltage and the isolation voltage share a common ground; The amplification module is configured to collect the positive voltage and the negative voltage of the device under test when receiving the isolation voltage and the bias voltage, and amplify the differential voltage between the positive voltage and the negative voltage to output an amplified voltage; wherein the amplified voltage and the isolation voltage share a common ground; The isolation module is used to isolate the amplified voltage when receiving the amplified voltage, and output a sampling voltage to the control device; wherein the sampling voltage and the DC voltage share a common ground.

2. The sampling circuit according to claim 1, wherein: The isolated power supply module includes a driver chip U1, a transformer T1, and a rectifier chip U2; Pin 5 of the driver chip U1 is connected to the first power supply, pin 2 of the driver chip U1 is connected to the first ground, pin 6 of the driver chip U1 is connected to the first input end of the transformer T1, pin 4 of the driver chip U1 is connected to the second input end of the transformer T1, the first output end of the transformer T1 is connected to pin 4 of the rectifier chip U2, the second input end of the transformer T1 is connected to pin 5 of the rectifier chip U2, pin 3 of the rectifier chip U2 is respectively connected to the bias power supply module, the amplification module, and the isolation module, and pins 1 and 2 of the rectifier chip U2 are both connected to the second ground; wherein, pin 3 of the rectifier chip U2 is used to output the isolation voltage.

3. The sampling circuit according to claim 1, wherein: The bias power supply module includes a resistor R14, a resistor R15, a resistor R16, a voltage reference source U3, and a capacitor C14; The first end of the resistor R14 is connected to the isolated power supply module, the second end of the resistor R14 is respectively connected to the first end of the resistor R15, the first end of the voltage reference source U3, the first end of the capacitor C14 and the amplification module, the second end of the resistor R15 is connected to the first end of the resistor R16 and the second end of the voltage reference source U3, the second end of the resistor R16, the third end of the voltage reference source U3, and the second end of the capacitor C14 are connected and are all connected to the second ground; wherein, the second end of the resistor R14 is used to output the bias voltage.

4. The sampling circuit according to claim 1, wherein: The amplification module includes a resistor R19, a resistor R24, a capacitor C19, a capacitor C20, a capacitor C21, and a monitoring chip U4; The first end of the resistor R19 is connected to the positive electrode of the device under test, the first end of the resistor R24 ​​is connected to the negative electrode of the device under test, pin 3 of the monitoring chip U4 is connected to the second end of the resistor R19 and the first end of the capacitor C19, pin 4 of the monitoring chip U4 is connected to the second end of the resistor R24 ​​and the first end of the capacitor C20, the second end of the capacitor C19 and the second end of the capacitor C20 are both connected to the second ground, pin 2 of the monitoring chip U4 is connected to the second ground, pin 5 of the monitoring chip U4 is connected to the bias power supply module, pin 6 of the monitoring chip U4 is connected to the first end of the capacitor C21 and the isolation power supply module, the second end of the capacitor C21 is connected to the second ground, and pin 1 of the monitoring chip U4 is connected to the isolation module; wherein, pin 1 of the monitoring chip U4 is used to output the amplified voltage.

5. The sampling circuit according to claim 4, characterized in that: The amplification module further includes a resistor R18, a resistor R23, a magnetic bead L5, a magnetic bead L6, a bidirectional TVS tube D5, and a bidirectional TVS tube D6; The first end of the resistor R18 is connected to the positive electrode of the device under test, the second end of the resistor R18 is connected to the second end of the bidirectional TVS tube D5 and the first end of the ferrite bead L5, the first end of the bidirectional TVS tube D5 is connected to the second ground, the second end of the ferrite bead L5 is connected to the first end of the resistor R19, the first end of the resistor R23 is connected to the negative electrode of the device under test, the second end of the resistor R23 is connected to the second end of the bidirectional TVS tube D6 and the first end of the ferrite bead L6, the first end of the bidirectional TVS tube D6 is connected to the second ground, and the second end of the ferrite bead L6 is connected to the first end of the resistor R24.

6. The sampling circuit according to claim 1, wherein: The isolation module includes a first operational amplifier unit, an isolation unit, and a second operational amplifier unit; The first operational amplifier unit is connected to the amplification module, the isolation unit is connected to the first operational amplifier unit, the second operational amplifier unit, and the isolated power supply module respectively, and the second operational amplifier unit is also connected to the first power supply and the control device; The first operational amplifier unit is configured to output a first voltage upon receiving the amplified voltage; wherein the first voltage and the isolation voltage share a common ground; The isolation unit is configured to isolate the amplified voltage and output an amplified isolated voltage upon receiving the first voltage; wherein the amplified isolated voltage and the DC voltage share a common ground; The second operational amplifier unit is configured to output the sampling voltage based on the amplified isolation voltage when receiving the amplified isolation voltage.

7. The sampling circuit according to claim 6, characterized in that: The first operational amplifier unit includes an operational amplifier U8A, a resistor R20, a resistor R21, a capacitor C15, and a capacitor C16; The first end of the resistor R20 is connected to the amplification module, the second end of the resistor R20 is connected to the inverting input end of the operational amplifier U8A, the first end of the capacitor C15 and the isolation unit, the non-inverting input end of the operational amplifier U8A is connected to the second ground, the output end of the operational amplifier U8A is connected to the second end of the capacitor C15 and the first end of the resistor R21, the second end of the resistor R15 is connected to the isolation unit, pin 8 of the operational amplifier U8A is connected to the first end of the capacitor C16 and the isolated power supply module, the second end of the capacitor C16 is connected to the second ground, pin 4 of the operational amplifier U8A is connected to the second ground, and the second end of the resistor R21 is used to output the first voltage.

8. The sampling circuit according to claim 6, wherein: The isolation unit includes a capacitor C18 and an optical coupler P1; Pin 1 of the optocoupler P1 is connected to the first operational amplifier unit, pin 2 of the optocoupler P1 is connected to the first end of the capacitor C18 and the isolated power supply module, the second end of the capacitor C18 is connected to the second ground, pin 3 of the optocoupler P1 is connected to the first operational amplifier unit, pin 4 of the optocoupler P1 is connected to the second ground, pin 5 of the optocoupler P1 is connected to the second operational amplifier unit and to the first ground, and pin 6 of the optocoupler P1 is connected to the second operational amplifier unit.

9. The sampling circuit according to claim 6, wherein: The second operational amplifier unit includes an operational amplifier U5A, a resistor R17, a resistor R22, a capacitor C17, and a dual series diode D4; The inverting input terminal of the operational amplifier U5A is connected to the first end of the resistor R17 and the isolation unit, the non-inverting input terminal of the operational amplifier U5A is connected to the isolation unit and to the first ground, the output terminal of the operational amplifier U5A is connected to the second end of the resistor R17 and the first end of the resistor R22, pin 8 of the operational amplifier U5A is connected to the first end of the capacitor C17 and the first power supply, the second end of the capacitor C17 is connected to the first ground, pin 4 of the operational amplifier U5A is connected to the first ground, the second end of the resistor R22 is connected to the third end of the dual-series diode D4 and the control device, the second end of the dual-series diode D4 is connected to the second power supply, and the first end of the dual-series diode D4 is connected to the first ground; wherein, the second end of the resistor R22 is used to output the sampling voltage.

10. A sampling device, characterized in that: The sampling device comprises the sampling circuit according to any one of claims 1 to 9.

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