Measurement circuit

Abstract

The present invention belongs to the field of high-precision measurement and provides a measurement circuit, including multiple sampling branches, a first drive isolation module, a second drive isolation module, a measurement module, and a sampling branch signal control module. The sampling branches include sampling branches in an off state and sampling branches in an on state. Each sampling branch includes a first switch component, a sampling resistor, and a second switch component. The first switch component generates a first source signal according to an electrical signal of a signal source and transmits it to the first drive isolation module for the first drive isolation module to generate a first sampling signal. The second switch component transmits a second source signal generated by the first source signal through the sampling resistor to the second drive isolation module for the second drive isolation module to generate a second sampling signal. The sampling branch signal control module generates a protection signal according to the second sampling signal and transmits it to the sampling branch to limit leakage current of the sampling branch.

Description

Technical Field

[0001] The present invention relates to the field of high-precision measurement, and in particular to a measurement circuit. Background Art

[0002] Electronic devices often incorporate multiple signal sources within their circuits, transmitting electrical signals to various load circuits. During the R&D, debugging, or production testing phases of electronic devices, it's necessary to test the electrical parameters of the load circuits to ensure that the product's performance meets expectations. For example, testing the load circuit's current can ensure it meets design requirements. Because different load circuits can have a wide range of current levels, multiple current range detection circuits are required.

[0003] The conventional method of measuring the load circuit current is to connect the measuring circuit in series between the power supply and the load to calculate the current value of the power supply into the load circuit. For precision electronic equipment, the measuring circuit is often as follows Figure 1 As shown, a measurement branch and multiple sampling branches connected in parallel are provided. Each sampling branch is provided with a sampling resistor of a different resistance value. One of the sampling branches can be selected to be in the on state and the other sampling branches in the off state to achieve sampling and measurement of different current signals. Since the sampling branches are connected in parallel, when one sampling branch is in the on state, the voltage at the first end of the other sampling branches in the off state is equal to the voltage at the first end of the sampling branch in the on state, so it is IS+. The voltage at the second end of the sampling branch in the off state is equal to the voltage at the second end of the sampling branch in the on state, so it is IS-. Therefore, there is a voltage difference between the first and second ends of the sampling branch in the off state. Therefore, even if the sampling branch is in the off state, leakage current will be generated. These leakage currents from the sampling branch in the off state affect the measured value of the current of the sampling branch in the on state, thereby increasing the measurement error. In other words, the measurement signal I detected by the measurement branch is senseVout In fact, it includes the leakage current of the sampling branch in the off state and the effective current actually introduced into the load by the sampling branch in the on state. Therefore, the performance of the electronic equipment debugged according to the existing technology does not meet the requirements of high-precision applications.

[0004] Therefore, as the requirements for equipment precision become increasingly higher, it is necessary for technicians to develop a measurement circuit to accurately detect the circuit information transmitted to the load, and reduce the impact of leakage current caused by other sampling branches in the off state on the detection results when sampling in a certain sampling branch. Summary of the Invention

[0005] The object of the present invention is to provide a measurement circuit to reduce the influence of leakage current on the detection result of load current caused by other sampling branches in the off state when one of the sampling branches is turned on for sampling.

[0006] To achieve the above purpose, the measuring circuit of the present invention adopts the following scheme:

[0007] A measuring circuit is used to electrically connect a load circuit and a signal source to obtain a signal to be measured corresponding to the load circuit; the measuring circuit includes multiple sampling branches, a first drive isolation module, a second drive isolation module, a measuring module, and a sampling branch signal control module;

[0008] Multiple sampling branches are connected in parallel with each other, each sampling branch includes a first switch component, a sampling resistor and a second switch component. When the measurement circuit is working, one of the sampling branches is in the on state to sample the signal, and the other sampling branches are in the off state.

[0009] The first switch component is connected to the signal source, the first drive isolation module, and the sampling resistor, and the first drive isolation module is connected to the measurement module; wherein, in the sampling branch in the conductive state, the first switch component transmits the electrical signal output by the signal source to the sampling resistor to obtain a first source signal, and transmits the first source signal to the first drive isolation module; the first drive isolation module generates a first sampling signal based on the first source signal and transmits the first sampling signal to the measurement module;

[0010] The second switch component is connected to the sampling resistor, the load circuit, the second drive isolation module, and the sampling branch signal control module, and the second drive isolation module is connected to the sampling branch signal control module and the measurement module; wherein, in the sampling branch in the conductive state, the second switch component transmits a second source signal obtained by passing the first source signal through the sampling resistor to the second drive isolation module, and the second drive isolation module generates a second sampling signal based on the second source signal and transmits it to the sampling branch signal control module and the measurement module;

[0011] The sampling branch signal control module generates a protection signal based on the second sampling signal and transmits the protection signal to the second switch component. The difference between the value of the protection signal and the value of the second source signal is within a first preset range. The measurement module obtains the measured signal corresponding to the load circuit based on the first sampling signal and the second sampling signal.

[0012] By adopting the above technical solution, the signal source generates an electrical signal PAout which is then transmitted to the load circuit after passing through the measurement circuit, thereby ensuring that the measurement circuit can detect the electrical parameters received by the load circuit, including current or voltage.

[0013] In the sampling branch in the on state, the first switch component converts the electrical signal PAout into a first source signal IS+ and transmits it to the sampling resistor and the first driver isolation module. The first driver isolation module generates a first sampling signal ISV+ based on the first source signal IS+ and transmits it to the measurement module. The first source signal IS+ becomes a second source signal IS- after passing through the sampling resistor. The second switch component transmits the second source signal IS- to the second driver isolation module and the load circuit. The second driver isolation module generates a second sampling signal ISV- based on the second source signal IS- and transmits it to the measurement module. The measurement module obtains the measured signal I according to the first sampling signal ISV+ and the second sampling signal ISV-. senseVout , to detect the electrical parameters of the input load circuit, such as current.

[0014] In the sampling branch in the on-state, the second source signal IS- output by the second switch component and the second sampling signal ISV- generated after passing through the second drive isolation module are also transmitted to the sampling branch signal control module. The sampling branch signal control module generates a protection signal Guard based on the second sampling signal ISV-, and then imports the protection signal Guard into the second switch component. On the one hand, the protection signal Guard is imported into the second switch component in the sampling branch in the off-state, so as to suppress the leakage current of the sampling branch in the off-state, and avoid leakage current in the sampling branch in the off-state when detecting the electrical parameters (such as current) of the load circuit, thereby affecting the measurement accuracy of the measurement circuit. On the other hand, the protection signal Guard is imported into the sampling resistor in the sampling branch in the on-state, which can also suppress the leakage current in the sampling branch in the on-state, and ensure that the sampling branch in the on-state maintains low leakage current. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of a module of a load current measurement circuit in the background art;

[0016] Figure 2 for Figure 1 Circuit diagram of the load current measurement circuit;

[0017] Figure 3 yes Figure 2 A circuit diagram of the first sampling branch in FIG.

[0018] Figure 4 yes Figure 2 The circuit diagram of the eighth sampling branch;

[0019] Figure 5 A schematic diagram of a module of a measurement circuit provided by a first embodiment of the present invention;

[0020] Figure 6 yes Figure 5 Schematic diagram of the module of the sampling branch;

[0021] Figure 7 yes Figure 6 A schematic diagram of a module for a sampling branch in an on-state and a sampling branch in an off-state;

[0022] Figure 8 yes Figure 5 Another module schematic diagram of the sampling branch in the on state and the sampling branch in the off state;

[0023] Figure 9 yes Figure 7 Circuit diagram of the sampling branch;

[0024] Figure 10 yes Figure 8 Circuit diagram of the sampling branch;

[0025] Figure 11 is a module schematic diagram of a measurement circuit provided by a second embodiment of the present invention;

[0026] Figure 12 is another module schematic diagram of a measurement circuit provided in a second embodiment of the present invention;

[0027] Figure 13 for Figure 11 A circuit diagram of a sampling branch signal control module;

[0028] Figure 14 for Figure 11 Another circuit diagram of the sampling branch signal control module;

[0029] Figure 15 for Figure 11 A circuit diagram of a sampling branch;

[0030] Figure 16 for Figure 12 A circuit diagram of a sampling branch;

[0031] Figure 17 A circuit diagram of a second embodiment of the present invention using a floating power supply to power a relay, and a schematic diagram showing how the voltage difference between the relay coil and the contact switch changes over time;

[0032] Figure 18 This is a circuit diagram of a second embodiment of the present invention using a floating power supply to power a relay, and a schematic diagram of the voltage difference between the relay coil and the contact switch varying with position. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the invention belongs. The words "including" and similar words used in this article mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0034] The background technology provides a load current measurement circuit, such as Figure 1 and Figure 2 As shown, the signal source source supplies power to the load Rload through the measurement circuit. The measurement circuit includes a measurement branch and multiple sampling branches connected in parallel. The sampling branches have an on state and an off state. There is one sampling branch in the on state, and the other sampling branches are in the off state. Specifically, the sampling branches in the off state include the first sampling branch S1, the second sampling branch S2, the third sampling branch S3, the fourth sampling branch S4, the fifth sampling branch S5, the sixth sampling branch S6, and the seventh sampling branch S7. The sampling branch in the on state is the eighth sampling branch S8. The measurement branch has a first measurement input terminal, a second measurement input terminal and a measurement output terminal. The measurement output terminal of the measurement branch serves as the output terminal of the measurement circuit for outputting the measurement signal I senseVout .

[0035] The sampling branch in the off state is Figure 2 Take the first sampling branch S1 in the example as an example. The specific circuit structure is as follows Figure 3 As shown, the first sampling branch S1 includes a first relay J10, a second relay J11, and a first sampling resistor R1. Both ends of the coils of the first relay J10 and the second relay J11 are connected to the ground signal GND. The first end of the contact switch ISW10 in the first relay J10 is connected to the first measurement input end of the measurement branch, the second end of the contact switch ISW10 in the first relay J10 is connected to the first end of the first sampling resistor R1, the first end of the contact switch ISW11 in the second relay J11 is connected to the signal source source, the second end of the contact switch ISW11 in the second relay J11 is connected to the first end of the first sampling resistor R1, the second end of the first sampling resistor R1 is connected to the second measurement input end of the measurement branch, and the second end of the first sampling resistor R1 is also connected to the load Rload.

[0036] The sampling branch of the conduction state is Figure 2Take the eighth sampling branch S8 in the circuit as an example. The specific circuit structure is as follows Figure 4 As shown, the eighth sampling branch S8 includes a fifteenth relay J80, a sixteenth relay J81, and an eighth sampling resistor R8. One end of the coils of the fifteenth relay J80 and the sixteenth relay J81 is connected to a positive electrical signal coil+ generated by a fixed power supply Vcc, and the other end of the coils of the fifteenth relay J80 and the sixteenth relay J81 is connected to a ground signal GND generated by a fixed power supply Vcc. A first end of a contact switch ISW80 in the fifteenth relay J80 is connected to a first measurement input terminal of the measurement branch, a second end of the contact switch ISW80 in the fifteenth relay J80 is connected to a first end of the eighth sampling resistor R8, a first end of the contact switch ISW81 in the sixteenth relay J81 is connected to a signal source source, a second end of the contact switch ISW81 in the sixteenth relay J81 is connected to a first end of the eighth sampling resistor R8, a second end of the eighth sampling resistor R8 is connected to a second measurement input terminal of the measurement branch, a second end of the eighth sampling resistor R8 is further connected to a first end of a load Rload, and a second end of the load Rload is grounded or connected to another circuit.

[0037] Analyze the load current measurement circuit in the background technology:

[0038] In the on-state sampling branch, the coil of the sixteenth relay J81 is connected to the positive electrical signal coil+ and the ground signal GND, respectively, causing the voltage difference across the coil to exceed the threshold voltage of the contact switch ISW81 of the sixteenth relay J81. The contact switch ISW81 of the sixteenth relay J81 closes, causing the signal source source to transmit the electrical signal PAout through the sixteenth relay J81, the eighth sampling resistor R8, and finally the load Rload. The coil of the fifteenth relay J80 is connected to the positive electrical signal coil+ and the ground signal GND, causing the voltage difference across the coil to exceed the threshold voltage of the contact switch ISW80 of the fifteenth relay J80. The contact switch ISW80 of the fifteenth relay J80 closes, transmitting the first source signal IS+, generated by transmitting the electrical signal PAout from the signal source source to the eighth sampling resistor R8, into the measurement branch.

[0039] Figure 2 Since the sampling branches S1~S7 in the off state are connected in parallel with the sampling branch S8 in the on state, the voltage between the two ends of the sampling branches S1~S7 in the off state is the same as the voltage between the two ends of the sampling branch S8 in the on state. Therefore, there is a voltage difference between the two ends of the sampling branches S1~S7 in the off state, which generates a leakage current I Leakage1总 ~I Leakage7总 The leakage sources of the sampling branch in the off state are:

[0040] (1) The voltages between the two contacts of the contact switches in the sampling branches S1 to S7 in the off state are different, resulting in leakage current.

[0041] Since the sampling branches S1 to S7 in the off state are connected in parallel with the sampling branch S8 in the on state, taking the first sampling branch S1 as an example, the voltage at the contact A of the first relay J0 in the first sampling branch S1 = the voltage at the switch contact of the fifteenth relay J80 in the eighth sampling branch S8 = the voltage at the input end of the eighth sampling resistor R8 in the eighth sampling branch S8 = the voltage transmitted by the first source signal IS+; the voltage at the contact B of the first relay J0 in the first sampling branch S1 = the voltage V19 at the output end of the first sampling resistor R1 in the first sampling branch S1 = the voltage V89 at the output end of the eighth sampling resistor R8 in the eighth sampling branch S8 = the voltage transmitted by the second source signal IS-. A voltage difference exists between the input and output terminals of the eighth sampling resistor R8 in the on-state sampling branch, resulting in a voltage difference between the first source signal IS+ and the second source signal IS-. This also creates a voltage difference between contacts A and B of the contact switch ISW10 of the first relay J0 in the first sampling branch. Due to the small distance between contacts A and B, leakage current occurs between the two contacts of the switch ISW10 of the first relay J0. Similarly, a voltage difference exists between contacts C and D of the switch ISW11 of the second relay J1, causing leakage current to occur between the two contacts of the switch ISW11 of the second relay J1. Therefore, when the on-state sampling branch S8 is operating, the voltages between the two contacts of the contact switches in the off-state sampling branches S1-S7 differ, resulting in leakage current.

[0042] (2) In the off state, the voltage between the contact switch (especially contact B) and the relay coil in the sampling branches S1 to S7 is different, resulting in leakage current.

[0043] Based on the above analysis, when sampling branch S8 (in the on-state) is operating, one or both ends of the coil of first relay J0 in sampling branches S1-S7 (in the off-state) are connected to ground signal GND. This creates a voltage differential between contact B in first relay J0 and the coil of first relay J0 in first sampling branch S1 (it should be noted that, in theory, there is also a voltage differential between contact A in first relay J0 and the coil of first relay J0, and leakage current will also occur between contact A and the coil of first relay J0. However, this leakage current does not flow into the load and, therefore, does not affect the measured current). This results in leakage current between the contact switch and the coil of first relay J0. Similarly, a voltage differential also exists between the contact switch and the coil of second relay J1, resulting in leakage current. When sampling branch S8 (in the on-state) is operating, the voltages between the contact switch and the relay coils in sampling branches S1-S7 (in the off-state) differ, resulting in leakage current.

[0044] (3) In the off state, the voltage between the contact switch (especially contact B) and the housing in the sampling branches S1 to S7 is different, and leakage current occurs between the two.

[0045] Based on the above analysis, the housings of the various electronic components in the measurement circuit are typically connected to the ground signal GND. When the sampling branch S8 is operating in the on state, a voltage difference is generated between contact B of the contact switch of the first relay J0 in the off state of the first sampling branch S1 and the housing of the first relay J0. (It should be noted that, in theory, there is also a voltage difference between contact A of the contact switch of the first relay J0 and the housing of the first relay J0, and leakage current will also occur between contact A and the housing of the first relay J0. However, this leakage current does not flow into the load, and therefore, this leakage current does not affect the measured current.) Therefore, a voltage difference exists between the contact switch of the first relay J0 in the first sampling branch and the housing of the electronic component, and leakage current exists between the contact switch of the first relay J0 and the housing. Similarly, a voltage difference also exists between the contact of the contact switch of the second relay J1 and the housing of the electronic component, and leakage current occurs between the contact switch of the second relay J1 and the housing of the electronic component. When the sampling branch S8 in the on state is operating, the voltages between the contact switches and the housings of the electronic components in the sampling branches S1 to S7 in the off state are different, resulting in leakage current.

[0046] In summary, when the sampling branch S8 in the conducting state is running, corresponding first leakage currents ( Figure 2 These first leakage currents constitute the second leakage current (e.g. I Leakage10 , I Leakage11 ), the second leakage current of all relays in the sampling branch S1 to S7 in the off state constitutes the third leakage current of the sampling branch in the entire off state (for example, I Leakage1总 , I Leakage2总 ...I Leakage7总 ), these third leakage currents and the real current I Leakage8总 Together they constitute the measured current I senseVout ,Right now,

[0047] The measurement signal I detected by the measurement branch senseVout In fact, it includes the leakage current of the sampling branch in the off state and the effective current actually introduced into the load of the sampling branch in the on state. There is a deviation between the value of the measured signal and the true value. Therefore, the performance of the electronic equipment debugged according to the existing technology does not meet the requirements of high-precision applications.

[0048] First embodiment:

[0049] The first embodiment of the present invention provides a measuring circuit 10, such as Figure 5 As shown, measurement circuit 10 is connected in series with load circuit 20 and signal source 30. The output of signal source 30 is connected to the input of measurement circuit 10 to transmit electrical signal PAout, and the output of measurement circuit 10 is connected to the input of load circuit 20. Measurement circuit 10 is used to measure the signal to be measured, such as an electrical signal, i.e., current, transmitted from signal source 30 to load circuit 20. Measurement circuit 10 includes a sampling branch 101, a first drive isolation module 102, a second drive isolation module 103, a measurement module 104, and a sampling branch signal control module 105.

[0050] The measurement circuit 10 generally has multiple sampling branches 101, which are connected in parallel. Among all the parallel sampling branches 101, only one sampling branch 101 is allowed to be turned on and serves as the sampling branch 101-1 in the on-state, while the other sampling branches 101 are turned off and serve as the sampling branches 101-2 in the off-state.

[0051] Each sampling branch 101 has an electrical signal input terminal, an electrical signal output terminal, a first sampling output terminal, a second sampling output terminal, and a control receiving terminal. The first drive isolation module 102 has a first drive isolation input terminal and a first drive isolation output terminal. The second drive isolation module 103 has a second drive isolation input terminal and a second drive isolation output terminal. The measurement module 104 has a first measurement input terminal, a second measurement input terminal, and a measurement output terminal. The sampling branch signal control module 105 has a control input terminal and a control output terminal.

[0052] The electrical signal input terminal of sampling branch 101 serves as the input terminal of measurement circuit 10 and is connected to the output terminal of signal source 30 to receive electrical signal PAout output by signal source 30. The electrical signal output terminal of sampling branch 101 is connected to the input terminal of load circuit 20. The first sampling output terminal of sampling branch 101 is connected to the first driving isolation input terminal of first driving isolation module 102 to transmit the first source signal IS+ generated by sampling branch 101 to first driving isolation module 102; the first driving isolation output terminal of first driving isolation module 102 is connected to the first measurement input terminal of measurement module 104 to transmit the first sampling signal ISV+ generated based on the first source signal IS+ to measurement module 104.

[0053] The second sampling output of sampling branch 101 is connected to the second drive isolation input of second drive isolation module 103 to transmit the second source signal IS- generated by sampling branch 101 to second drive isolation module 103. The second drive isolation output of second drive isolation module 103 is connected to the second measurement input of measurement module 104 and the control input of sampling branch signal control module 105, respectively, to transmit the second sampling signal ISV- generated based on the second source signal IS- to measurement module 104 and sampling branch signal control module 105. The control receiving end of sampling branch 101 is connected to the control output of sampling branch signal control module 105 to receive the protection signal Guard from sampling branch signal control module 105.

[0054] The measurement module 104 generates a signal to be measured I according to the first sampling signal ISV+ and the second sampling signal ISV-. senseVout The control output terminal of the sampling branch signal control module 105 is connected to the control receiving terminal of the sampling branch 101 , and is used to transmit the protection signal Guard generated according to the second sampling signal ISV- to the control input terminal of the sampling branch 101 .

[0055] In this example, the signal source 30 generates an electrical signal PAout and transmits it to the load circuit 20 via the sampling branch 101. The sampling branch 101-1 is on, and the sampling branch 101-2 is off, ensuring that the measurement circuit 10 can detect the electrical signal received by the load circuit 20.

[0056] In this case, the sampling branch 101-1 in the conductive state converts the electrical signal PAout into a first source signal IS+ and transmits it to the first driver isolation module 102. The first driver isolation module 102 generates a first sampling signal ISV+ based on the first source signal IS+. In addition, the sampling branch 101-1 in the conductive state also generates a second source signal IS- based on the first source signal IS+ and transmits it to the second driver isolation module 103. The second driver isolation module 103 generates a second sampling signal ISV- based on the second source signal IS-.

[0057] The sampling branch signal control module 105 generates a protection signal Guard based on the second sampling signal ISV-, and transmits the protection signal Guard to the sampling branch 101-1 in the on state to further suppress the leakage current generated by the sampling branch 101-1 in the on state, and transmits the protection signal Guard to the sampling branch 101-2 in the off state to change the voltage of the connection line between the sampling branch 101-2 in the off state and the load circuit 20, thereby limiting the voltage difference between the two ends of the sampling branch 101-2 in the off state, thereby suppressing the leakage current generated by the sampling branch 101-2 in the off state during the operation of the sampling branch 101-1 in the on state, thereby ensuring the final measurement accuracy.

[0058] The following is a detailed description of the implementation details of a measurement circuit 10 in this embodiment. The following content is only provided for easy understanding of the implementation details.

[0059] (1) Regarding the structure of the sampling branch 101:

[0060] A basic example of the circuit structure of the sampling branch 101 is:

[0061] refer to Figure 6 Sampling branch 101 is divided into a sampling branch 101-1 in the on state and a sampling branch 101-2 in the off state. Each sampling branch 101 has an electrical signal input terminal, an electrical signal output terminal, a first sampling output terminal, a second sampling output terminal, and a control receiving terminal. Each sampling branch 101 includes a first switch component 1011, a sampling resistor 1012, and a second switch component 1013.

[0062] The first switch component 1011 is connected to the signal source 30, the first drive isolation module 102 and the sampling resistor 1012. The port of the first switch component 1011 connected to the signal source 30 serves as the electrical signal input end of the sampling branch 101. The port of the first switch component 1011 connected to the first drive isolation module 102 serves as the first sampling output end of the sampling branch 101. The first drive isolation module 102 is connected to the measurement module 104. The first switch component 1011 is connected to the first end of the sampling resistor 1012.

[0063] The second switch component 1013 is connected to the sampling resistor 1012, the load circuit 20, the second drive isolation module 103 and the sampling branch signal control module 105. The second switch component 1013 is connected to the sampling resistor 1012. The connection port of the second switch component 1013 and the load circuit 20 serves as the electrical signal output end of the sampling branch 101. The connection port of the second switch component 1013 and the second drive isolation module 103 serves as the second sampling output end of the sampling branch 101. The second drive isolation module 103 is connected to the sampling branch signal control module 105 and the measurement module 104. The port of the second switch component 1013 connected to the sampling branch signal control module 105 serves as the control receiving end of the sampling branch 101.

[0064] During operation, only one sampling branch 101 is turned on, becoming sampling branch 101-1 in the on-state, while the other sampling branches 101 remain off, becoming sampling branches 101-2 in the off-state. When sampling branch 101-1 in the on-state is operating, first switch component 1011 transmits electrical signal PAout from signal source 30 to the first end of sampling resistor 1012, and generates a first source signal IS+ based on the electrical signal transmitted to sampling resistor 1012, which is then transmitted to first driver isolation module 102. First driver isolation module 102 generates a first sampling signal ISV+ based on the first source signal IS+ and transmits it to measurement module 104.

[0065] The second switch component 1013 transmits the second source signal IS− obtained by passing the first source signal IS+ through the sampling resistor 1012 to the second driver isolation module 103. The second driver isolation module 103 generates a second sampling signal ISV− according to the second source signal IS− and transmits it to the sampling branch signal control module 105 and the measurement module 104.

[0066] The sampling branch signal control module 105 generates a protection signal Guard according to the second sampling signal ISV-, and transmits the protection signal Guard to the second switch component 1013 of the sampling branch 101-1 in the on state and the sampling branch 101-2 in the off state. The difference between the value of the protection signal Guard and the value of the second source signal IS- is within a first preset range. The measurement module 104 obtains the measured signal I corresponding to the load circuit 20 according to the first sampling signal ISV+ and the second sampling signal ISV-. senseVout .

[0067] In this basic example, the first switch component 1011 generates a first source signal IS+ based on an electrical signal PAout from a signal source 30. The second switch component 1013 generates a second source signal IS- based on the electrical signal PAout after passing through a sampling resistor 1012. The sampling branch signal control module 105 generates a protection signal Guard based on the second source signal IS- transmitted by the conductive sampling branch 101-1 via the second sampling signal ISV- generated by the second driver isolation module 103. The protection signal Guard is then transmitted to the second switch component 1013, thereby ensuring that the voltage at the end of the second switch component 1013 connected to the sampling resistor 1012 is approximately equal to the voltage at the end of the second switch component 1013 connected to the load circuit 20. In other words, the difference between the value of the protection signal Guard and the value of the second source signal IS- is within a first preset range. The first preset range is typically pre-set. To ensure leakage current is limited, the difference between the value of the protection signal Guard and the value of the second source signal IS- is as small as possible, meaning that the generated protection signal Guard must be as close to the second source signal IS- as possible. The first preset range can be the component error range of the second driver isolation module 103 and the sampling branch signal control module 105 during signal transmission. In this case, the difference between the value of the protection signal Guard and the value of the second source signal IS- is smaller, thereby ensuring that when the protection signal Guard is transmitted back to the second switch component 1013, the voltages across the second switch component 1013 of the sampling branch 101-2 in the off state are approximately equal, and the voltages across the second switch component 1013 of the sampling branch 101-1 in the on state are approximately equal, thereby ensuring that the leakage current of each switch component is reduced.

[0068] Furthermore, the specific structures of the first switch component 1011 and the second switch component 1013 in the above basic example are as follows:

[0069] refer to Figure 7 and Figure 8 The first switch component 1011 in the sampling branch 101 includes a first relay K0 and a second relay K1, the second switch component 1013 includes a third relay K2, a fourth relay K3 and a fifth relay K4, the first drive isolation module 102 has a first drive isolation input terminal and a first drive isolation output terminal, and the second drive isolation module 103 has a second drive isolation input terminal and a second drive isolation output terminal.

[0070] The first end of the second relay K1 is electrically connected to the signal source 30 as the electrical signal input end of the sampling branch 101. The second end of the second relay K1 is connected to the first end of the sampling resistor 1012. The first end of the fourth relay K3 is connected to the second end of the sampling resistor 1012. The second end of the fourth relay K3 is connected to the load circuit 20 as the electrical signal output end of the sampling branch 101 to supply power to the load circuit 20. The second end of the first relay K0 is connected to the first end of the sampling resistor 1012. The first end of the first relay K0 is connected to the first end of the sampling resistor 1012. The first end of the first relay K0 is connected to the first drive isolation input end of the first driver isolation module 102 as the first sampling output end to transmit the first source signal IS+ from the signal source 30 to the sampling resistor 1012 through the second relay K1. The first end of the third relay K2 is connected to the second end of the sampling resistor 1012. The second end of the third relay K2 is connected to the second drive isolation input end of the second driver isolation module 103 as the second sampling output end to transmit the second source signal IS- output by the first source signal IS+ through the sampling resistor 1012 to the second driver isolation module 103.

[0071] The first driving isolation module 102 generates a first sampling signal ISV+ according to the first source signal IS+, the second driving isolation module 103 generates a second sampling signal ISV- according to the second source signal IS-, and the measuring module 104 generates an ISV according to the first sampling signal ISV+ and the second sampling signal ISV-. senseVout The ISV- generated by the second driving isolation module is also transmitted to the sampling branch signal control module 105 so that the sampling branch signal control module 105 can generate the protection signal Guard.

[0072] In this example, the protection signal Guard is transmitted to the sampling branch 101 through the fifth relay K4. On the one hand, the protection signal Guard is introduced into the sampling resistor 1012 in the sampling branch 101-2 in the off state, so as to suppress the leakage current of the sampling branch 101-2 in the off state, thereby preventing the sampling branch 101-2 in the off state, which is connected in parallel with the sampling branch 101-1 in the on state, from generating leakage current when detecting the circuit information of the load circuit 20, thereby affecting the measurement accuracy of the measurement circuit 10; on the other hand, the protection signal Guard is introduced into the sampling branch 101-1 in the on state, which can suppress the leakage current in the sampling branch 101-1 in the on state, thereby ensuring that the sampling branch 101-1 in the on state maintains low leakage current.

[0073] The following describes two ways in which the protection signal Guard is transmitted to the sampling branch 101 through the fifth relay K4:

[0074] The first one: reference Figure 7The second end of the fifth relay K4 is connected to the protection signal Guard, and the first end of the fifth relay K4 is connected to the second end of the sampling resistor 1012 .

[0075] Because the difference between the value of the protection signal Guard and the value of the second source signal IS- is within a first preset range, that is, the value of the protection signal Guard is close to the value of the second source signal IS-, the protection signal transmitted to the sampling branch 101 causes the voltage value at the second end of the sampling resistor 1012 to be equal to the value of the protection signal Guard, and the voltage value at the first end of the load circuit to be equal to the value of the second source signal IS-. Therefore, the voltage at the second end of the sampling resistor 1012 is close to the voltage at the first end of the load circuit 20, thereby suppressing leakage current of the sampling branch 101-2 in the off state and suppressing leakage current of the sampling branch 101-1 in the on state.

[0076] Circuit implementation reference Figure 9 The signal source 30 outputs the PAout electrical signal, and the fixed power supply Vcc generates the ground signal GND and the positive electrical signal coil+. In the first switch assembly 1011, the first relay K0 includes a first control coil and a first contact switch ISWx0. The second relay K1 includes a second control coil and a second contact switch ISWx1. In the second switch assembly 1013, the third relay K2 includes a third control coil and a third contact switch ISWx2. The fourth relay K3 includes a fourth control coil and a fourth contact switch ISWx3. The fifth relay K4 includes a fifth control coil and a fifth contact switch ISWx4.

[0077] A first end of the second contact switch ISWx1 is connected to the output of the signal source 30, and a second end of the second contact switch ISWx1 is connected to the first end of the sampling resistor 1012. A first end of the first contact switch ISWx0 is connected to the first drive isolation input of the first drive isolation module 102, and a second end of the first contact switch ISWx0 is connected to the first end of the sampling resistor 1012. A first end of the third contact switch ISWx2 is connected to the second end of the sampling resistor 1012, and a second end of the third contact switch ISWx2 is connected to the second drive isolation input of the second drive isolation module 103. A first end of the fourth contact switch ISWx3 is connected to the second end of the sampling resistor 1012, and a second end of the fourth contact switch ISWx3 is connected to the load circuit 20. A first end of the fifth contact switch ISWx4 is connected to the second end of the sampling resistor 1012, and a second end of the fifth contact switch ISWx4 is connected to the control output of the sampling branch signal control module 105 to receive the protection signal Guard.

[0078] In the on-state sampling branch 101-1, one end of the first control coil is connected to the positive electrical signal coil+, and the other end of the first control coil is connected to the ground signal GND. One end of the second control coil is connected to the positive electrical signal coil+, and the other end of the second control coil is connected to the ground signal GND. One end of the third control coil is connected to the positive electrical signal coil+, and the other end of the third control coil is connected to the ground signal GND. One end of the fourth control coil is connected to the positive electrical signal coil+, and the other end of the fourth control coil is connected to the ground signal GND. One or both ends of the fifth control coil are connected to the ground signal GND. In the off-state sampling branch 101-2, one or both ends of the first control coil are connected to the ground signal GND, one or both ends of the second control coil are connected to GND, one or both ends of the third control coil are connected to the ground signal GND, one or both ends of the fourth control coil are connected to the ground signal GND, one end of the fifth control coil is connected to the positive electrical signal coil+, and the other end of the fifth control coil is connected to the ground signal GND.

[0079] for Figure 9 Explanation of the numbers in the circuit in: For the first contact switch ISWx0, the second contact switch ISWx1, the third contact switch ISWx2, the fourth contact switch ISWx3, and the fifth contact switch ISWx4, "x" means the number of each sampling branch. This number is only used to distinguish different switches in different sampling branches. For example, the first contact switch in the first sampling branch is written as ISW10, and the first contact switch in the second sampling branch is written as ISW20.

[0080] for Figure 9 The circuit in is discussed as follows:

[0081] In the on-state sampling branch 101-1, one end of the second control coil is connected to the positive electrical signal coil+, and the other end of the second control coil is connected to the ground signal GND. The voltage difference across the second control coil exceeds the threshold voltage of the second contact switch ISW81, and the second contact switch ISW81 is closed. Similarly, one end of the fourth control coil is connected to the positive electrical signal coil+, and the other end of the fourth control coil is connected to the ground signal GND. The voltage difference across the fourth control coil exceeds the threshold voltage of the fourth contact switch ISW83, and the fourth contact switch ISW83 is closed, ensuring that the electrical signal PAout is transmitted through the second relay K1, the sampling resistor Rsense8, and the fourth relay K3 to reach the load circuit 20.

[0082] One end of the first control coil is connected to the positive electrical signal coil+, and the other end is connected to the ground signal GND. The voltage difference across the first control coil exceeds the threshold voltage of the first contact switch ISW80, closing the first contact switch ISW80. The first relay K0 generates a first source signal IS+ based on the PAout at the first end of the sampling resistor Rsense8, which is then transmitted to the first driver isolation module 102. One end of the third control coil is connected to the positive electrical signal coil+, and the other end is connected to the ground signal GND. The voltage difference across the third control coil exceeds the threshold voltage of the third contact switch ISW82, closing the third contact switch ISW82, and the third relay K2 generates a second source signal IS- based on the signal at the second end of the sampling resistor Rsense8, which is then transmitted to the second driver isolation module 103. The second driver isolation module 103 generates a second sampling signal ISV- based on the second source signal IS-, and the sampling branch control module 105 generates a protection signal Guard based on the second sampling signal ISV-.

[0083] One or both ends of the fifth control coil are connected to the ground signal GND. The voltage difference across the fifth control coil does not exceed the threshold voltage of the fifth contact switch ISW84, and the fifth contact switch ISW84 is disconnected. The switch contact corresponding to the first end of the fifth contact switch ISW84 is connected to the second end of the sampling resistor Rsense8, and the switch contact corresponding to the second end of the fifth contact switch ISW84 is connected to the protection signal Guard.

[0084] The possibility of leakage current forming in the sampling branch 101 - 1 in the on state is discussed as follows:

[0085] In the on-state sampling branch 101-1, the protection signal Guard is transmitted to the second end of the fifth contact switch ISW84 of the fifth relay K4 via the control output end of the sampling branch signal control module 105. The voltage at the first end of the fifth contact switch ISW84 of the fifth relay K4 is the second source signal IS-, and the second source signal IS- is the same as the voltage of the protection signal Guard. Therefore, in the on-state sampling branch 101-1, no leakage current occurs across the fifth contact switch ISW84.

[0086] In the off state of sampling branch 101-2, one or both ends of the first, second, third, and fourth control coils are connected to the ground signal GND. One end of the fifth control coil is connected to the positive electrical signal coil+, and the other end of the fifth control coil is connected to the ground signal GND. Because the voltage difference across the first, second, third, and fourth control coils does not reach the threshold voltage, the first contact switch ISW10, the second contact switch ISW11, the third contact switch ISW12, and the fourth contact switch ISW13 all remain off.

[0087] One end of the fifth control coil is connected to the positive electrical signal coil+, and the other end is connected to the ground signal GND. The conductive fifth coil closes the fifth contact switch ISW14, so that the protection signal Guard is transmitted to the second end of the sampling resistor Rsense1 through the fifth relay K4, so that the voltage at the second end of the sampling resistor Rsense1 is the same as the voltage of the protection signal Guard.

[0088] The possibility of leakage current forming in the sampling branch 101 - 2 in the off state is discussed as follows:

[0089] 1. The first end of the third contact switch ISW12 in the third relay K2 is connected to the second end of the sampling resistor Rsense1, so that the contact voltage at the first end of the third contact switch ISW12 is the same as the voltage of the protection signal Guard. The second end of the third contact switch ISW12 is connected to the second end of the third contact switch ISW82 in the on-state sampling branch 101-1. Therefore, the contact voltage corresponding to the second end of the third contact switch ISW12 is the same as the second source signal IS-. Because the protection signal Guard and the second source signal IS- have almost the same voltage and the protection signal Guard follows the second source signal IS-, the voltages at both ends of the third contact switch ISW12 are almost the same, and no leakage current occurs across the third contact switch ISW12.

[0090] 2. The first end of the fourth contact switch ISW13 in the fourth relay K3 is connected to the second end of the sampling resistor Rsense1, so that the contact voltage at the first end of the fourth contact switch ISW13 is the same as the voltage of the protection signal Guard. The second end of the fourth contact switch ISW13 is connected to the fourth contact switch ISW83 of the sampling branch 101-1, which is in the on state. Therefore, the contact voltage at the second end of the fourth contact switch ISW13 is the same as the second source signal IS-. Because the protection signal Guard and the second source signal IS- have almost the same voltage and the protection signal Guard follows the second source signal IS-, the voltages at both ends of the fourth contact switch ISW13 are almost the same, and no leakage current occurs at both ends of the fourth contact switch ISW13.

[0091] 3. The leakage current of the first relay K0 and the second relay K1 does not pass through the sampling resistor 1012 . Therefore, the leakage current generated by the first relay K0 and the second relay does not affect the overall leakage current result.

[0092] It should be noted that Figure 9 In the structure shown, the second end of the load circuit 20 is shown as being grounded. However, in actual use, the second end of the load circuit 20 may be connected to other circuit structures.

[0093] In summary, in this embodiment, a protection signal Guard is generated during operation of the sampling branch 101-1 in the on-state, and is introduced into the second end of the fifth contact switch ISW84 in the on-state sampling branch 101-1, so that the voltage at the first end and the voltage at the second end of the fifth contact switch ISW84 are the same, thereby ensuring that the voltages at both ends of the fifth contact switch ISW84 in the on-state are the same, suppressing the generation of leakage current in the on-state sampling branch 101-1, and ensuring that the leakage current of the on-state sampling branch 101-1 is maintained at a low level. In addition, the protection signal Guard is input to the second end of the sampling resistor Rsense1 through the fifth relay K4 of the sampling branch 101-2 in the off state, so that the voltages across the third contact switch ISW12 and the fourth contact switch ISW13 in the off state are almost the same, thereby suppressing the leakage current between the third contact switch ISW12 and the fourth contact switch ISW13, thereby limiting the leakage current generated by the sampling branch 101-2 in the off state, and preventing the leakage current generated by the sampling branch 101-2 in the off state from affecting the overall measurement result.

[0094] The second type: reference Figure 8 , secondly, Figure 8 The realization of the circuit can refer to Figure 10 , the power supply module signal source 30 outputs a PAout electrical signal (represented as coil). Figure 8 The realization of the circuit and Figure 7 The difference between Figure 10 and Figure 9 The difference between the two is as follows: a first end of the fifth contact switch ISWx4 is connected to the first end of the sampling resistor 1012, and a second end of the fifth contact switch ISWx4 is connected to the control output end of the sampling branch signal control module 105 to access the protection signal Guard.

[0095] A second end of the fifth relay K4 is connected to the protection signal Guard, and a first end of the fifth relay K4 is connected to the first end of the sampling resistor 1012 .

[0096] Because the difference between the value of the protection signal Guard and the value of the second source signal IS- is within a first preset range, that is, the value of the protection signal Guard is close to the value of the second source signal IS-, the protection signal Guard transmitted to the sampling branch 101 causes the voltage value at the first end of the sampling resistor 1012 to be equal to the value of the protection signal Guard, and the voltage value at the first end of the load circuit to be equal to the value of the second source signal IS-. Therefore, the voltage at the first end of the sampling resistor 1012 is close to the voltage at the first end of the load circuit 20, thereby suppressing leakage current of the sampling branch 101-2 in the off state and suppressing leakage current of the sampling branch 101-1 in the on state.

[0097] Circuit implementation reference Figure 10 A first end of the fifth contact switch ISWx4 is connected to the first end of the sampling resistor 1012 , and a second end of the fifth contact switch ISWx4 is connected to the control output end of the sampling branch signal control module 105 to receive the protection signal Guard.

[0098] The leakage current of the sampling branch 101 - 1 in the on state is described as follows:

[0099] Since the first end of the fifth contact switch ISWx4 of the fifth relay K4 is connected to the first end of the sampling resistor 1012, even if leakage current is generated by the first relay K0, the second relay K1, and the fifth relay K4, it will not pass through the sampling resistor 1012 and will not affect the sampling result. Therefore, the sampling branch 101-1 in the conductive state maintains a low leakage current.

[0100] The leakage current of the sampling branch 101 - 2 in the off state is described as follows:

[0101] 1. The fifth contact switch ISW14 is closed, and the fifth relay K4 transmits the protection signal Guard to the first end of the sampling resistor Rsense1. Since the first contact switch ISW10 and the second contact switch ISW11 are turned off, the voltage at the second end of the sampling resistor Rsense1 and the voltage at the first end of Rsense1, as well as the voltage at the first end of the third contact switch ISW12 and the fourth contact switch ISW13 are all the voltage of the protection signal Guard. The voltage at the second end of the third contact switch ISW12 is the voltage of the second source signal IS-. The voltage at the first end of the third contact switch ISW12 and the voltage at the first end of the third contact switch ISW13 are all the voltage of the protection signal Guard. The voltages at the two ends are almost the same, and the third contact switch ISW12 does not generate leakage current. The second end of the fourth contact switch ISW13 is connected to ISW83 of the sampling branch 101-1 in the on state and the load circuit 20. The voltage at the second end of the fourth contact switch ISW13 is almost the same as the voltage of the second source signal IS-. The voltage at the first end of the fourth contact switch ISW13 is almost the same as the voltage at the second end. The fourth contact switch ISW13 does not generate leakage current, thereby limiting the leakage current generated by the sampling branch 101-2 in the off state, thereby preventing the leakage current of the sampling branch 101-2 in the off state from affecting the overall measurement result.

[0102] 2. The leakage current of the first relay K0 and the second relay K1 does not pass through the sampling resistor 1012 . Therefore, the leakage current generated by the first relay K0 and the second relay K1 does not affect the overall leakage current result.

[0103] It should be noted that Figure 9 and 10 In the illustrated structure, the second terminal of the load circuit 20 is shown as grounded. However, in actual use, the second terminal of the load circuit 20 can be connected to other circuit structures. The first relay K0, the second relay K1, the third relay K2, the fourth relay K3, and the fifth relay K4 all support various forms of integration (for example, shared control coil pins). The control logic, generation of the protection signal Guard, and the introduction of the protection signal Guard into the sampling branch are the same as in this embodiment, and can achieve the effects described in the above example, thus remaining within the scope of protection of the present invention.

[0104] (2) Regarding the structure of the first drive isolation module 102:

[0105] A basic example of the circuit structure of the first drive isolation module 102 is:

[0106] like Figure 7 and Figure 8As shown, the first driver isolation module 102 has a first driver isolation input and a first driver isolation output, and the measurement module 104 has a first measurement input and a second measurement input. The first driver isolation module 102 includes a third operational amplifier OPAO. The non-inverting input of the third operational amplifier OPAO serves as the first driver isolation input, connected to the first switch component 1011. The inverting input of the third operational amplifier OPAO is connected to the output of the third operational amplifier OPAO. The output of the third operational amplifier OPAO serves as the first driver isolation output, connected to the first measurement input of the measurement module 104.

[0107] The connection method of the third operational amplifier OPA0 ensures that the output first sampling signal ISV+ can follow the input first source signal IS+. In other words, the level of the first source signal IS+ is approximately equal to the first sampling signal ISV+. The third operational amplifier OPA0 has the characteristics of high input impedance and low output impedance.

[0108] (3) Regarding the structure of the second drive isolation module 103:

[0109] A basic example of the circuit structure of the second drive isolation module 103 is:

[0110] like Figure 7 and Figure 8 As shown, the second driver isolation module 103 has a second driver isolation input and a second driver isolation output, and the measurement module 104 has a first measurement input and a second measurement input. The second driver isolation module 103 includes a fourth operational amplifier OPA1. The non-inverting input of the fourth operational amplifier OPA1 serves as the second driver isolation input, connected to the second switch component 1013. The inverting input of the fourth operational amplifier OPA1 is connected to the output of the fourth operational amplifier OPA1. The output of the fourth operational amplifier OPA1 serves as the second driver isolation output, connected to the second measurement input of the measurement module 104 and the sampling branch signal control module 105.

[0111] (4) Regarding the structure of the measurement module 104:

[0112] A basic example of the circuit structure of the measurement module 104 is:

[0113] like Figure 7 and Figure 8As shown, the measurement module 104 has a first measurement input terminal, a second measurement input terminal, and an output terminal. The measurement module 104 includes a differential amplifier OPA2. The non-inverting input terminal of the differential amplifier OPA2 is connected to the first drive isolation output terminal of the first drive isolation module 102 as the first measurement input terminal, and the inverting input terminal of the differential amplifier OPA2 is connected to the second drive isolation output terminal of the second drive isolation module 103 as the second measurement input terminal. The output terminal of the differential amplifier OPA2 serves as the output terminal of the measurement module 104 to output the measured signal I corresponding to the load circuit 20. senseVout .

[0114] (5) Regarding the structure of the sampling branch control module 105:

[0115] A basic example of the circuit structure of the sampling branch control module 105 is:

[0116] like Figure 7 and Figure 8 As shown, the sampling branch signal control module 105 generates the protection signal Guard according to the second sampling signal ISV- by either a staff member allocating the protection signal Guard according to the second sampling signal ISV- or designing a power supply conversion circuit to automatically convert the second sampling signal ISV- into the protection signal Guard.

[0117] In the basic example, Figure 7 As shown, the sampling branch signal control module 105 is configured as a protection signal driving unit OPA3, which is used to generate a protection signal Guard based on the second sampling signal ISV-. The protection signal driving unit OPA3 includes a first signal input terminal and a protection signal output terminal, wherein the protection signal output terminal serves as the control output terminal of the sampling branch signal control module 105, and the first signal input terminal serves as the control input terminal of the sampling branch signal control module 105.

[0118] Specific circuit reference Figure 7 The protection signal driving unit OPA3 includes a first operational amplifier, the output end of the first operational amplifier serves as the protection signal output end, the non-inverting input end of the first operational amplifier serves as the first signal input end and is connected to the output end of the second driving isolation module 103 to receive the second sampling signal ISV-, the inverting input end of the first operational amplifier is connected to the output end, and the output end of the first operational amplifier serves as the protection signal output end to output the protection signal Guard.

[0119] Based on the above basic example, further examples are given:

[0120] like Figure 6 、 Figure 9 and Figure 10As shown, the sampling branch signal control module 105 is connected to all housings of electronic components in the first switch component 1011 and the second switch component 1013 to provide a protection signal Guard to the housings of the electronic components in the first switch component 1011 and the second switch component 1013 .

[0121] The sampling branch signal control module 105 provides a protection signal Guard to the housing of the electronic components in the first switch component 1011 and the second switch component 1013 to prevent leakage between the conductive part of the electronic components and the housing when the first switch component 1011 and the second switch component 1013 are in operation, thereby affecting the measurement accuracy.

[0122] For example, the sampling branch signal control module 105 provides a protection signal Guard to the housings of different relays in the first switch component 1011 and the second switch component 1013, thereby further preventing leakage between the contact switches and the housings of different relays.

[0123] Second embodiment:

[0124] A second embodiment of the present invention provides a measurement circuit. The difference between the measurement circuit provided in this embodiment and the first embodiment is that:

[0125] like Figure 11 As shown, the sampling branch signal control module 105 generates a protection signal Guard according to the second sampling signal ISV-, and also generates a floating power supply signal and a floating ground signal RGND, and provides the floating power supply signal or the floating ground signal RGND to the first switch component 1011, and provides the floating power supply signal and the floating ground signal RGND to the second switch component 1013. The difference between the value of the floating power supply signal and the value of the second sampling signal ISV- is within a second preset range, and the difference between the value of the floating ground signal RGND and the value of the second sampling signal is within a third preset range.

[0126] Preferably, the floating power signal includes a floating positive signal coil+ and a floating negative signal coil-, and the floating power signal is a floating symmetrical power signal. In this embodiment, the sampling branch control module 105 has a power signal output terminal, through which the floating power signal and the floating ground signal RGND can be provided to the first switch component 1011.

[0127] The second preset range is typically pre-set. To ensure leakage current is limited, the difference between the floating power supply signal and the second source signal IS- is as small as possible. In other words, the generated floating power supply signal must be as close to the second source signal IS- as possible. The third preset range is typically pre-set. To ensure leakage current is limited, the difference between the floating ground signal RGND and the second source signal IS- is as small as possible. In other words, the generated floating ground signal RGND must be as close to the second source signal IS- as possible. It should be noted that the second and third preset ranges are set to the tolerance ranges allowed by the device itself during signal transmission.

[0128] In this embodiment, a floating power supply (including a floating positive signal coil+, a floating negative signal coil-, and a floating ground signal RGND) is used to replace the fixed power supply Vcc (positive electrical signal coil+, ground signal GND) in the first embodiment to power the coils of all relays.

[0129] refer to Figure 18 When the positive and negative terminals of the relay control coil are powered by a floating positive signal (coil+) and a floating negative signal (coil-), the contact switch is on. When one or both terminals are connected to a floating ground signal (RGND), the contact switch is off. Assuming one end of the relay control coil is point A, the other end is point B, and the midpoint of the coil is point C, the resistance of the relay control coil is evenly distributed. Therefore, the voltage difference between two symmetrical points An and Bn on the relay coil (between the relay coil and the contact switch) about C is equal in magnitude and opposite in direction. The sum of the two is zero, and the leakage current at all symmetrical points between the coil and the contact switch cancels out. Therefore, when a floating power supply is used to power the relay, the leakage current generated between the relay coil and the contact switch cancels out and does not affect the current signal transmitted by the contact switch.

[0130] refer to Figure 17 In the left and right figures, RGND is the reference ground for Coil0+ and Coil0-. The voltage difference between Coil0+ and RGND is V0, and the voltage between Coil0- and RGND is V0. Since RGND is close to IS-, the voltage difference between Coil0+ and IS- is V0, and the voltage between Coil0- and IS- is V0. ΔV0+ = V0, and ΔV0- = -V0. Figure 17 It can be seen that no matter how IS- changes, ΔV0+=V0 and ΔV0-=-V0 remain unchanged, thus ensuring that the leakage between the relay coil and the switch contacts remains unchanged.

[0131] It's worth noting that the sampling branch signal control module 105 can switch between the floating positive signal coil+ / floating negative signal coil- and the floating ground signal RGND provided to the first switch component 1011 and the second switch component 1013. That is, the user can select one of the multiple sampling branches 101 as the on-state sampling branch 101-1 and the other sampling branches 101 as the off-state sampling branches based on their needs. The sampling branch signal control module 105 then adjusts the electrical signals provided by the sampling branch signal control module 105 to the first switch component 1011 and the second switch component 1013 in the sampling branch 101-1 set to the on-state, as well as the electrical signals provided by the sampling branch signal control module 105 to the first switch component 1011 and the second switch component 1013 in the sampling branch 101-2 set to the off-state. It should be noted that the sampling branch signal control module 105 can provide a floating power supply signal (floating positive signal coil+ / floating negative signal coil-) or a floating ground signal RGND to the first switch component 1011 and the second switch component 1013 by switching switches.

[0132] The floating power supply signal uses a floating symmetrical power supply signal to ensure that when it is applied to the second switch component 1013, the leakage current generated by the second switch component 1013 itself is reduced in a symmetrical manner, reducing the leakage current between the coil of each relay and the contact switch, ensuring that the second switch component 1013 in the sampling branch 101-1 in the on state does not generate leakage current to affect the overall measurement accuracy of the measurement circuit.

[0133] (1) Regarding the structure of the sampling branch signal control module 105:

[0134] In some examples, such as Figure 11 and Figure 12 As shown, the sampling branch signal control module 105 includes a protection signal driving unit OPA3 and a floating power driving unit OPA4. The protection signal driving unit OPA3 includes a first signal input terminal and a protection signal output terminal. The floating power driving unit OPA4 includes a second signal input terminal and a floating ground signal output terminal. The second drive isolation module 103 includes a second drive isolation input terminal and a second drive isolation output terminal. The sampling branch signal control module 105 also includes a power signal output terminal.

[0135] The second drive isolation input terminal of the second drive isolation module 103 is connected to the second terminal of the third relay K2 in the second switch component 1013 to obtain the second source signal IS- flowing into the load circuit 20 from the sampling resistor 1012. The module generates a second sampling signal ISV- based on the second source signal IS- and outputs it from the second drive isolation output terminal. The second drive isolation output terminal of the second drive isolation module 103 is connected to the first signal input terminal of the protection signal driver unit OPA3 and the second signal input terminal of the floating power supply driver unit OPA4, so that the protection signal driver unit OPA3 and the floating power supply driver unit OPA4 can obtain the second sampling signal ISV-.

[0136] The protection signal output terminal of the protection signal driving unit OPA3 is connected to the second terminal of the fifth relay K4 in the second switch component 1013 as the control output terminal of the sampling branch signal control module 105. The protection signal driving unit OPA3 generates a protection signal Guard according to the second sampling signal ISV- and transmits the protection signal Guard to the second switch component 1013. Specifically, the first terminal of the second switch component 1013 can be connected to the second terminal of the sampling resistor 1012 (such as Figure 10 As shown), the first end of the second switch component 1013 can also be connected to the first end of the sampling resistor 1012 (as shown Figure 11 shown).

[0137] The floating power drive unit OPA4 generates a floating ground signal RGND according to the second sampling signal ISV-, and outputs it through the floating ground signal output end, so that the sampling branch control module 105 uses the floating ground signal as a reference to generate a floating power signal (floating positive signal coil+ / floating negative signal coil-), and provides the floating power signal (floating positive signal coil+ / floating negative signal coil-) or the floating ground signal RGND to the first switch component 1011 through the power signal output end of the sampling branch control module 105, and provides the floating power signal (floating positive signal coil+ / floating negative signal coil-) and the floating ground signal RGND to the second switch component 1013.

[0138] Further, if Figure 11 and Figure 13 As shown, the protection signal driving unit OPA3 includes a first operational amplifier, the output end of the first operational amplifier serves as the protection signal output end, and the protection signal output end serves as the control output end of the sampling branch signal control module 105, the non-inverting input end of the first operational amplifier serves as the first signal input end, and the inverting input end of the first operational amplifier is connected to the output end;

[0139] The floating power drive unit OPA4 includes a second operational amplifier, the output end of the second operational amplifier serves as the floating ground signal output end, the non-inverting input end of the second operational amplifier serves as the second signal input end, and the inverting input end of the second operational amplifier is connected to the output end.

[0140] In other examples, such as Figure 14 As shown, the sampling branch signal control module 105 includes a voltage driving unit OPA5, which includes a third signal input terminal and a third signal output terminal. The second driving isolation output terminal of the second driving isolation module 103 is connected to the third signal input terminal of the voltage driving unit OPA5 to transmit the second sampling signal ISV-. The voltage driving unit generates a protection signal Guard and a floating ground signal RGND according to the second sampling signal ISV-. The sampling branch control module uses the floating ground signal RGND as a reference to generate a floating power supply signal, and provides the floating power supply signal or the floating ground signal RGND to the first switch component 1011 through the power supply signal output terminal, and provides the floating power supply signal and the floating ground signal RGND to the second switch component 1013. The third signal output terminal of the voltage driving unit OPA5 is connected to the second switch component 1013 as the control output terminal of the sampling branch control module 105, and the voltage driving unit OPA5 also transmits the protection signal Guard to the second switch component 1013.

[0141] In some examples, such as Figure 11 、 Figure 12 、 Figure 15 and Figure 16 As shown, the sampling branch signal control module 105 generates a protection signal Guard, a floating ground signal RGND, a floating positive signal coil+, and a floating negative signal coil-. The floating positive signal coil+ and the floating negative signal coil- constitute a floating power supply signal.

[0142] like Figure 15 and Figure 16 As shown, the sampling branch signal control module 105 is further connected to the first switch component 1011 in the sampling branch 101 and provides a protection signal "Guard" to the housing of the electronic components in the first switch component 1011. The sampling branch signal control module 105 also provides a protection signal "Guard" to the housing of the electronic components in the second switch component 1013. Since the leakage current of the first switch component 1011 in the sampling branch 101 does not affect the measurement signal of the system, the sampling branch signal control module 105 is further connected to the first switch component 1011 in the sampling branch 101 and provides a floating ground signal "RGND" to the housing of the electronic components in the first switch component 1011.

[0143] The sampling branch signal control module 105 provides a protection signal Guard to the housing of the electronic components in the first switch component 1011 and the second switch component 1013 to prevent leakage between the conductive part of the electronic components and the housing when the first switch component 1011 and the second switch component 1013 are in operation, thereby affecting the measurement accuracy.

[0144] For example, the sampling branch signal control module 105 may provide a protection signal Guard to the housings of different relays in the first switch component 1011 and the second switch component 1013 , thereby further preventing leakage between the contact switches and housings of different relays.

[0145] (2) Regarding the structure of the sampling branch 101:

[0146] The difference between the structure of the sampling branch 101 in this embodiment and that in the first embodiment lies in that the power supply method of the relay coil in the sampling branch is different.

[0147] like Figure 11 、 Figure 15 、 Figure 12 and Figure 16 As shown, the first switch assembly 1011 includes a first relay K0 and a second relay K1. The first relay K0 includes a first control coil and a first contact switch ISWx0, and the second relay K1 includes a second control coil and a second contact switch ISWx1. The second switch assembly 1013 includes a third relay K2, a fourth relay K3, and a fifth relay K4. The third relay K2 includes a third control coil and a third contact switch ISWx2, the fourth relay K3 includes a fourth control coil and a fourth contact switch ISWx3, and the fifth relay K4 includes a fifth control coil and a fifth contact switch ISWx4.

[0148] In the on-state sampling branch 101-1, both ends of the first and second control coils are connected to a floating power supply signal, while both ends of the third and fourth control coils are connected to a floating power supply signal. For example, the first ends of the first, second, third, and fourth control coils are connected to the floating positive signal coil+ of the floating power supply signal, and the second ends of the first, second, third, and fourth control coils are connected to the floating negative signal coil- of the floating power supply signal, thereby closing the first through fourth contact switches ISWx0 through ISWx3. The fifth control coil is connected to a floating ground signal RGND. That is, one end of the fifth control coil is connected to the floating ground signal RGND, or both ends of the fifth control coil are connected to the floating ground signal RGND, thereby opening the fifth contact switch ISWx4.

[0149] In the off-state sampling branch 101-2, one or both ends of the first, second, third, and fourth control coils are connected to the floating ground signal RGND, thereby opening the first to fourth contact switches ISWx0 to ISWx3. Both ends of the fifth control coil are connected to the floating power supply signal. For example, the first end of the fifth control coil is connected to the floating positive signal coil+ of the floating power supply signal, and the second end of the fifth control coil is connected to the floating negative signal coil- of the floating power supply signal, thereby closing the fifth contact switch ISWx4.

[0150] In some examples, such as Figure 15 As shown, in the OFF state, the first end of the fifth contact switch ISW14 in the sampling branch 101-2 is connected to the second end of the sampling resistor 1012, and the second end of the fifth contact switch ISW14 is connected to the protection signal Guard. In the ON state, the first end of the fifth contact switch ISW84 in the sampling branch 101-2 is connected to the second end of the sampling resistor 1012, and the second end of the fifth contact switch ISW84 is connected to the protection signal Guard.

[0151] In some examples, such as Figure 16 As shown, in the OFF state, the first end of the fifth contact switch ISW14 in the sampling branch 101-2 is connected to the first end of the sampling resistor 1012, and the second end of the fifth contact switch ISW14 is connected to the protection signal Guard. In the ON state, the first end of the fifth contact switch ISW84 in the sampling branch 101-2 is connected to the first end of the sampling resistor 1012, and the second end of the fifth contact switch ISW84 is connected to the protection signal Guard. In addition, it should be noted that Figure 15 and Figure 16 In the figure, the second end of the load circuit 20 is shown as being grounded, but in actual use, the second end of the load circuit 20 can be connected to other circuit structures.

[0152] In this embodiment, as described in the first embodiment, leakage current will not basically occur at both ends of the third contact switch ISWx2, the fourth contact switch ISWx3, and the fifth contact switch ISWx4 in the sampling branch 101-1 in the on state and the sampling branch 101-2 in the off state, that is, leakage current will not occur in the sampling branch 101-1 in the on state and the sampling branch 101-2 in the off state. Furthermore, by providing a floating power supply signal to the first switch component 1011 and the second switch component 1013 through the sampling branch signal control module 105, the leakage current can be reduced. The leakage current between the coil of the relay and the contact switch further ensures the reduction of the leakage current of different sampling branches, and at the same time, the sampling branch signal control module 105 provides a protection signal Guard to the housing of all electronic components in the sampling branch 101 (such as the housing of the first relay K0 to the fifth relay K4 provides a protection signal), further avoiding the leakage current between the housing of the electronic component and the conductive part (such as the leakage current between the housing of the first relay K0 to the fifth relay K4 and their respective contact switches) during the operation of the first switch component 1011 and the second switch component 1013.

[0153] While the embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations of these embodiments are possible. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as set forth in the claims. Furthermore, the invention described herein is susceptible to other embodiments and may be practiced or implemented in a variety of ways.

Claims

1. A measuring circuit, characterized in that: The measuring circuit is used to electrically connect the load circuit and the signal source to obtain the measured signal corresponding to the load circuit; the measuring circuit includes a plurality of sampling branches, a first drive isolation module, a second drive isolation module, a measuring module, and a sampling branch signal control module; The plurality of sampling branches are connected in parallel with each other, each of the sampling branches comprises a first switch component, a sampling resistor and a second switch component. When the measurement circuit is working, one of the sampling branches is in a conducting state to sample the signal, and the remaining sampling branches are in a closed state. The first switch component is connected to the signal source, the first drive isolation module, and the sampling resistor, and the first drive isolation module is connected to the measurement module. In the sampling branch in the conductive state, the first switch component transmits the electrical signal output by the signal source to the sampling resistor to obtain a first source signal, and transmits the first source signal to the first drive isolation module. The first drive isolation module generates a first sampling signal based on the first source signal and transmits the first sampling signal to the measurement module. The second switch component is connected to the sampling resistor, the load circuit, the second drive isolation module, and the sampling branch signal control module, and the second drive isolation module is connected to the sampling branch signal control module and the measurement module; wherein, in the sampling branch in the conductive state, the second switch component transmits a second source signal obtained by passing the first source signal through the sampling resistor to the second drive isolation module, and the second drive isolation module generates a second sampling signal based on the second source signal and transmits the second sampling signal to the sampling branch signal control module and the measurement module; The sampling branch signal control module generates a protection signal based on the second sampling signal and transmits the protection signal to the second switch component, and the difference between the value of the protection signal and the value of the second source signal is within a first preset range; the measurement module obtains the signal to be measured corresponding to the load circuit based on the first sampling signal and the second sampling signal.

2. The measuring circuit according to claim 1, characterized in that The second drive isolation module includes a second drive isolation input terminal and a second drive isolation output terminal, and the sampling branch signal control module includes a protection signal driving unit, and the protection signal driving unit includes a first signal input terminal and a protection signal output terminal; The second driving isolation input terminal of the second driving isolation module is connected to the second switch component, the second driving isolation output terminal of the second driving isolation module is connected to the first signal input terminal of the protection signal driving unit, the protection signal output terminal of the protection signal driving unit is connected to the second switch component, and the protection signal driving unit generates a protection signal according to the second sampling signal and transmits the protection signal to the second switch component.

3. The measurement circuit according to claim 1, characterized in that The sampling branch signal control module further generates a floating power supply signal and a floating ground signal based on the second sampling signal, provides the floating power supply signal or the floating ground signal to the first switch component, and provides the floating power supply signal and the floating ground signal to the second switch component, wherein a difference between a value of the floating power supply signal and a value of the second sampling signal is within a second preset range, and a difference between a value of the floating ground signal and a value of the second sampling signal is within a third preset range.

4. The measuring circuit according to claim 3, characterized in that The floating power supply signal includes a floating positive signal and a floating negative signal, and the floating power supply signal is a floating symmetrical power supply signal.

5. The measurement circuit according to claim 3, characterized in that The sampling branch signal control module includes a protection signal driving unit and a floating power supply driving unit, the protection signal driving unit includes a first signal input terminal and a protection signal output terminal, the floating power supply driving unit includes a second signal input terminal and a floating ground signal output terminal, the second drive isolation module includes a second drive isolation input terminal and a second drive isolation output terminal, and the sampling branch signal control module includes a power supply signal output terminal; The second driving isolation input terminal of the second driving isolation module is connected to the second switch component, the second driving isolation output terminal of the second driving isolation module is connected to the first signal input terminal of the protection signal driving unit and the second signal input terminal of the floating power supply driving unit, the protection signal output terminal of the protection signal driving unit is connected to the second switch component, and the protection signal driving unit generates a protection signal according to the second sampling signal and transmits the protection signal to the second switch component; The floating power driving unit generates a floating ground signal according to the second sampling signal and outputs it through the floating ground signal output terminal, so that the sampling branch control module uses the floating ground signal as a reference to generate a floating power signal, and provides the floating power signal or the floating ground signal to the first switch component through the power signal output terminal, and provides the floating power signal and the floating ground signal to the second switch component.

6. The measuring circuit according to claim 5, characterized in that The protection signal driving unit includes a first operational amplifier, the output end of the first operational amplifier serves as the protection signal output end, the non-inverting input end of the first operational amplifier serves as the first signal input end, and the inverting input end of the first operational amplifier is connected to the output end; The floating power drive unit includes a second operational amplifier, the output end of the second operational amplifier serves as the floating ground signal output end, the non-inverting input end of the second operational amplifier serves as the second signal input end, and the inverting input end of the second operational amplifier is connected to the output end.

7. The measuring circuit according to claim 3, characterized in that The sampling branch signal control module includes a voltage driving unit, the voltage driving unit includes a third signal input terminal and a third signal output terminal, the second driving isolation module includes a second driving isolation input terminal and a second driving isolation output terminal, and the sampling branch signal control module includes a power signal output terminal; The second drive isolation input terminal of the second drive isolation module is connected to the second switch component, and the second drive isolation output terminal of the second drive isolation module is connected to the third signal input terminal of the voltage drive unit. The voltage drive unit generates a protection signal and a floating ground signal according to the second sampling signal, and outputs the floating ground signal through the third signal output terminal, so that the sampling branch control module uses the floating ground signal as a reference to generate a floating power supply signal, and provides the floating power supply signal or the floating ground signal to the first switch component through the power supply signal output terminal, and provides the floating power supply signal and the floating ground signal to the second switch component; the third signal output terminal is connected to the second switch component, and transmits the protection signal to the second switch component.

8. The measuring circuit according to any one of claims 5 to 7, characterized in that: The first switch assembly includes a first relay and a second relay, the first relay includes a first control coil and a first contact switch, the second relay includes a second control coil and a second contact switch, and the first drive isolation module includes a first drive isolation input terminal and a first drive isolation output terminal; One end of the second contact switch is connected to the output end of the signal source, the other end of the second contact switch is connected to the first end of the sampling resistor, one end of the first contact switch is connected to the first end of the sampling resistor, and the other end of the first contact switch is connected to the first drive isolation input end of the first drive isolation module; Among them, in the sampling branch in the on state, the two ends of the first control coil and the second control coil are respectively connected to the floating power supply signal to close the first contact switch and the second contact switch; in the sampling branch in the off state, the first control coil and the second control coil are respectively connected to the floating ground signal to open the first contact switch and the second contact switch.

9. The measuring circuit according to any one of claims 5 to 7, characterized in that: The second switch assembly includes a third relay, a fourth relay and a fifth relay; the third relay includes a third control coil and a third contact switch, the fourth relay includes a fourth control coil and a fourth contact switch, and the fifth relay includes a fifth control coil and a fifth contact switch; One end of the third contact switch is connected to the second end of the sampling resistor, and the other end of the third contact switch is connected to the second drive isolation input end of the second drive isolation module; one end of the fourth contact switch is connected to the second end of the sampling resistor, and the other end of the fourth contact switch is connected to the load circuit; one end of the fifth contact switch is connected to the second end of the sampling resistor, and the other end of the fifth contact switch is connected to the protection signal; Among them, in the sampling branch in the on-state, the two ends of the third control coil and the fourth control coil are respectively connected to the floating power supply signal to close the third contact switch and the fourth contact switch, and the fifth control coil is connected to the floating ground signal to turn off the fifth contact switch; in the sampling branch in the off-state, the third control coil and the fourth control coil are respectively connected to the floating ground signal to turn off the third contact switch and the fourth contact switch, and the two ends of the fifth control coil are connected to the floating power supply signal to close the fifth contact switch.

10. The measuring circuit according to any one of claims 5 to 7, characterized in that: The second switch assembly includes a third relay, a fourth relay, and a fifth relay; the third relay includes a third control coil and a third contact switch, the fourth relay includes a fourth control coil and a fourth contact switch, and the fifth relay includes a fifth control coil and a fifth contact switch, and the third control coil, the fourth control coil, and the fifth control coil are respectively connected to the power signal output terminal of the sampling branch signal control module; One end of the third contact switch is connected to the second end of the sampling resistor, and the other end of the third contact switch is connected to the second drive isolation input end of the second drive isolation module. One end of the fourth contact switch is connected to the second end of the sampling resistor, and the other end of the fourth contact switch is connected to the load circuit. One end of the fifth contact switch is connected to the first end of the sampling resistor, and the other end of the fifth contact switch is connected to the protection signal. The third control coil, the fourth control coil, and the fifth control coil are respectively connected to the power signal output end of the sampling branch signal control module. Among them, in the sampling branch in the on-state, the third control coil and the fourth control coil are connected to the floating power supply signal to close the third contact switch and the fourth contact switch, and the two ends of the fifth control coil are connected to the floating ground signal to turn off the fifth contact switch; in the sampling branch in the off-state, the third control coil and the fourth control coil are respectively connected to the floating ground signal to turn off the third contact switch and the fourth contact switch, and the two ends of the fifth control coil are connected to the floating power supply signal to close the fifth contact switch.

11. The measurement circuit according to claim 1, characterized in that The first driving isolation module includes a third operational amplifier, the second driving isolation module includes a fourth operational amplifier, and the measuring module includes a first measuring input terminal and a second measuring input terminal; The non-inverting input terminal of the third operational amplifier serves as a first isolation input terminal to be connected to the first switch component, the inverting input terminal of the third operational amplifier is connected to the output terminal of the third operational amplifier, and the output terminal of the third operational amplifier serves as a first driving isolation output terminal to be connected to the first measurement input terminal of the measurement module; The non-inverting input terminal of the fourth operational amplifier serves as the second driving isolation input terminal to connect the second switch component, the inverting input terminal of the fourth operational amplifier is connected to the output terminal of the fourth operational amplifier, and the output terminal of the fourth operational amplifier serves as the second driving isolation output terminal to connect the second measurement input terminal of the measurement module and the sampling branch signal control module.

12. The measuring circuit according to claim 11, characterized in that The measurement module includes a differential amplifier, wherein a non-inverting input terminal of the differential amplifier is connected to the first driving isolation output terminal of the first driving isolation module as the first measurement input terminal, an inverting input terminal of the differential amplifier is connected to the second driving isolation output terminal of the second driving isolation module as the second measurement input terminal, and an output terminal of the differential amplifier is connected to the second driving isolation output terminal of the second driving isolation module as the output terminal of the measurement module to output a signal to be measured corresponding to the load circuit.

13. The measuring circuit according to any one of claims 1 to 7 or any one of claims 11 to 12, characterized in that: The sampling branch signal control module is also connected to the first switch component in the sampling branch, and the sampling branch signal control module also provides the protection signal to the housing of the electronic component in the second switch component.

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