Voltage sampling circuit and electronic equipment

Abstract

According to the voltage sampling circuit and the electronic equipment, the voltage sampling circuit is provided with an impedance compensation circuit, the equivalent impedance of the inverted input end of an operational amplifier circuit is configured to be infinite, and the input impedance of the inverted input end under different sampling voltages is fixed, so that the influence on the resistance coefficient of the input front end is greatly reduced; the sampling precision of the voltage sampling circuit is greatly improved, and the sampling amplification gain consistency is good in a full input voltage range.

Description

Technical Field

[0001] This application belongs to the field of electronic circuit technology, and in particular relates to a voltage sampling circuit and electronic device. Background Technology

[0002] In the field of voltage detection technology, DC voltage sampling typically employs a non-isolated differential amplifier circuit. The input side of this differential amplifier circuit has two equal input resistors, and the feedback resistor is equal to the voltage divider resistor, ensuring a linear relationship between the output voltage and the input voltage. Therefore, in conventional voltage sampling circuits, a voltage divider circuit is connected in series with the input of the differential amplifier circuit. However, because the input impedance affects the voltage divider circuit's accuracy, especially within a small voltage range, the impact is significant, ultimately leading to a decrease in sampling accuracy. Summary of the Invention

[0003] In view of the above problems, this application provides a voltage sampling circuit and electronic device, which aims to solve the problem of low sampling accuracy of conventional voltage sampling circuits.

[0004] In a first aspect, embodiments of this application provide a voltage sampling circuit, including an operational amplifier circuit, a voltage divider circuit, a negative feedback circuit, and an impedance compensation circuit; the voltage divider circuit is connected to a signal source, the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit, and the voltage divider circuit is used to divide the output of the signal source and output voltage components to the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit; the negative feedback circuit is connected between the inverting input terminal and the output terminal of the operational amplifier circuit, and the impedance compensation circuit is coupled at least to the inverting input terminal of the operational amplifier circuit, and the impedance compensation circuit is used to configure the equivalent impedance of the inverting input terminal of the operational amplifier circuit to be infinite.

[0005] In the technical solution of this application embodiment, the voltage sampling circuit sets the equivalent impedance of the inverting input terminal of the operational amplifier circuit to infinity by setting an impedance compensation circuit, thereby fixing the input impedance of the inverting input terminal under different sampling voltages, greatly reducing the influence on the resistance coefficient of the input front end, greatly improving the sampling accuracy of the voltage sampling circuit, and achieving good consistency of sampling amplification gain across the entire input voltage range.

[0006] In some embodiments, the voltage sampling circuit further includes a bias current compensation circuit, which is coupled to at least one of the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit. The bias current compensation circuit is used to configure the external equivalent resistance of the non-inverting input terminal of the operational amplifier circuit to be equal to the external equivalent resistance of the inverting input terminal of the operational amplifier circuit.

[0007] In the technical solution of this application embodiment, the bias current compensation circuit makes the external equivalent resistance connected to the non-inverting input terminal of the operational amplifier circuit equal to the external equivalent resistance connected to the inverting input terminal of the operational amplifier circuit, thereby reducing the influence of the bias current and offset voltage of the operational amplifier circuit and improving the sampling accuracy.

[0008] In some embodiments, the bias current compensation circuit includes a first compensation resistor, which is coupled to the non-inverting input of the operational amplifier circuit.

[0009] In the technical solution of this application embodiment, when the external equivalent resistance connected to the non-inverting input terminal of the operational amplifier circuit is not equal to the external equivalent resistance connected to the inverting input terminal of the operational amplifier circuit, it can be compensated by the first compensation resistor coupled to the non-inverting input terminal of the operational amplifier circuit, so that the external equivalent resistance connected to the non-inverting input terminal of the operational amplifier circuit is equal to the external equivalent resistance connected to the inverting input terminal of the operational amplifier circuit.

[0010] In some embodiments, the bias current compensation circuit further includes a second compensation resistor, which is coupled to the inverting input terminal of the operational amplifier circuit.

[0011] In the technical solution of this application embodiment, when the external equivalent resistance connected to the non-inverting input terminal of the operational amplifier circuit is not equal to the external equivalent resistance connected to the inverting input terminal of the operational amplifier circuit, compensation can be made by the first compensation resistor and / or the second compensation resistor, so that the external equivalent resistance connected to the non-inverting input terminal of the operational amplifier circuit is equal to the external equivalent resistance connected to the inverting input terminal of the operational amplifier circuit.

[0012] In some embodiments, the voltage divider circuit includes a first voltage divider network, the input terminal of the first voltage divider network is used to connect to the signal source, and the output terminal of the first voltage divider network constitutes the output terminal of the voltage divider circuit.

[0013] In the technical solution of this application embodiment, a voltage divider network is used to divide the signal source to obtain voltage components, which are then applied to the non-inverting input terminal and the input circuit of the operational amplifier circuit. A sampling device can be placed in the first voltage divider network.

[0014] In some embodiments, the voltage divider circuit includes a first voltage divider network and a second voltage divider network. The input terminal of the first voltage divider network is used to connect to the signal source, and the output terminal of the first voltage divider network constitutes the first output terminal of the voltage divider circuit, which is connected to the inverting input terminal of the operational amplifier circuit. The input terminal of the second voltage divider network is used to connect to the signal source, and the output terminal of the second voltage divider network constitutes the second output terminal of the voltage divider circuit, which is connected to the non-inverting input terminal of the operational amplifier circuit.

[0015] In the technical solution of this application embodiment, two voltage divider networks are used to divide the signal source to obtain two voltage components, which are respectively applied to the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit. The sampling device can be disposed within the first voltage divider network and / or the second voltage divider network. Furthermore, the sampling device can be disposed within the first voltage divider network and / or the second voltage divider network. The two ground terminals of the first and second voltage divider networks are respectively grounded, providing two grounding points. If either voltage divider network fails, such as a short circuit or open circuit, it will not damage the subsequent circuits, posing no risk of damage to the voltage sampling circuit. Compared to traditional circuits, this method offers higher reliability.

[0016] In some embodiments, the first voltage divider network includes a first voltage divider and a second voltage divider. The first end of the first voltage divider constitutes the input terminal of the first voltage divider network, and the second end of the first voltage divider is connected to the first end of the second voltage divider to constitute the output terminal of the first voltage divider network. The second end of the second voltage divider is grounded.

[0017] In the technical solution of this application embodiment, the sampling device can be disposed in the first voltage divider and / or the second voltage divider.

[0018] In some embodiments, the second voltage divider network includes a third voltage divider and a fourth voltage divider. The first end of the third voltage divider constitutes the input terminal of the second voltage divider network, and the second end of the third voltage divider is connected to the first end of the fourth voltage divider to constitute the output terminal of the second voltage divider network. The second end of the fourth voltage divider is grounded.

[0019] In the technical solution of this application embodiment, the sampling device can be disposed in the third voltage divider and / or the fourth voltage divider.

[0020] Furthermore, the first, second, third, and fourth voltage dividers each have two grounding points. If any voltage divider fails, such as due to a short circuit or open circuit, it will not damage subsequent circuits and poses no risk of damage to the voltage sampling circuit. This results in higher reliability compared to traditional circuits.

[0021] In some embodiments, the voltage divider circuit further includes a fifth voltage divider, the first end of which is connected to the positive terminal of the power supply, and the second end of which is connected to the input terminal of the first voltage divider network and the input terminal of the second voltage divider network. The signal source includes the positive terminal of the power supply.

[0022] In the technical solution of this application embodiment, the fifth voltage divider is used to divide the power supply voltage, and the generated voltage component serves as the signal source for voltage detection generated by the voltage sampling circuit.

[0023] In some embodiments, the impedance compensation circuit includes an input impedance circuit, a first terminal of which is connected to the output terminal of the voltage divider circuit, and a second terminal of which is connected to the inverting input terminal of the operational amplifier circuit and the negative feedback circuit. The impedance of the input impedance circuit is the same as the impedance of the negative feedback circuit.

[0024] In the technical solution of this application embodiment, an implementation concept of an impedance compensation circuit is provided. When the impedance of the input impedance circuit is the same as the impedance of the negative feedback circuit, based on the negative feedback virtual short characteristic of the operational amplifier circuit, the voltages of the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit are made equal, so that the voltages at both ends of the input circuit are equal and no current flows through the input circuit, thereby achieving the purpose of making the equivalent impedance of the inverting input terminal of the operational amplifier circuit infinite.

[0025] In some embodiments, the impedance compensation circuit includes a current suppression component and an input impedance circuit. The first end of the current suppression component is connected to the output end of the voltage divider circuit, and the second end of the current suppression component is connected to the inverting input end of the operational amplifier circuit and the negative feedback circuit through the input impedance circuit. The current suppression component is used to suppress current from flowing through the input impedance circuit.

[0026] In the technical solution of this application embodiment, another implementation concept of impedance compensation circuit is provided. The current suppression component suppresses the current flowing through the input impedance circuit, so as to achieve the purpose of the equivalent impedance of the inverting input terminal of the operational amplifier circuit being infinite.

[0027] In some embodiments, the current suppression component includes two diodes connected in series with common anode and in opposite phase at the first terminal of the input impedance circuit.

[0028] In the technical solution of this application embodiment, the common anode of the two diodes can make it so that no current flows between the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit, thereby achieving the purpose of making the equivalent impedance of the inverting input terminal of the operational amplifier circuit infinite.

[0029] In some embodiments, the impedance compensation circuit includes the voltage divider circuit and the input impedance circuit. The output terminal of the voltage divider circuit is connected to the inverting input terminal of the operational amplifier and the negative feedback circuit through the input impedance circuit. The output terminal of the voltage divider circuit is also connected to the non-inverting input terminal of the operational amplifier circuit. The voltage divider circuit is used to output the voltage components with the same voltage value to the non-inverting input terminal of the operational amplifier circuit and the input impedance circuit.

[0030] In the technical solution of this application embodiment, another implementation concept of impedance compensation circuit is provided. The voltage divider circuit can use one or two voltage divider networks to divide the output of the signal source to obtain one voltage component or two voltage components with the same voltage value. These components are simultaneously applied to the non-inverting input terminal and the input impedance circuit of the operational amplifier circuit. Based on the negative feedback virtual short characteristic of the operational amplifier circuit, the voltages at the non-inverting and inverting input terminals of the operational amplifier circuit are made equal, so that the voltages at both ends of the input impedance circuit are equal and no current flows through the input impedance circuit. This achieves the goal of making the equivalent impedance of the inverting input terminal of the operational amplifier circuit infinite.

[0031] Secondly, embodiments of this application provide an electronic device including at least one voltage sampling circuit as described above.

[0032] In the technical solutions of this application embodiment, the use of two or more voltage sampling circuits in the electronic device ensures the accuracy of sampling to a greater extent.

[0033] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0034] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0035] Figure 1 This is a schematic diagram of the voltage sampling circuit provided in some embodiments of this application;

[0036] Figure 2 A circuit diagram of a voltage divider circuit in a voltage sampling circuit provided in some embodiments of this application;

[0037] Figure 3 A circuit diagram of a voltage sampling circuit provided in some embodiments of this application;

[0038] Figure 4 The simulation waveforms show the theoretical gain of a conventional differential amplifier circuit across its full input range of 0–3kV.

[0039] Figure 5 Simulation waveforms of the theoretical gain of the differential amplifier circuit for the voltage sampling circuit provided in some embodiments of this application, covering the full input range of 0–3kV;

[0040] Figure 6 The simulation diagram is for Monte Carlo analysis of a conventional differential amplifier circuit.

[0041] Figure 7 A simulation diagram of Monte Carlo analysis of the voltage sampling circuit provided in the embodiments of this application;

[0042] Figure 8 A circuit diagram of a voltage sampling circuit provided in some embodiments of this application;

[0043] Figure 9 A circuit diagram of a voltage sampling circuit provided in some embodiments of this application;

[0044] Figure 10 The output simulation diagram of the voltage sampling circuit provided in some embodiments of this application;

[0045] Figure 11 This is a schematic diagram of the voltage sampling circuit provided in some embodiments of this application. Detailed Implementation

[0046] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0048] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0049] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0050] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0051] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0052] In conventional voltage sampling circuits, a voltage divider circuit is connected in series with the input of a differential amplifier circuit. However, the input impedance affects the voltage divider circuit's accuracy, especially within a small voltage range, ultimately impacting sampling accuracy. Furthermore, within the small voltage range, the offset current of the actual operational amplifier (op-amp) also introduces significant errors, further reducing sampling accuracy.

[0053] In some solutions, sampling accuracy is improved by using low bias voltage and high precision operational amplifiers, but this generally increases the cost of the entire sampling circuit. Therefore, this application provides a voltage sampling circuit based on input impedance compensation.

[0054] Please see Figure 1 Some embodiments of this application provide a voltage sampling circuit, including an operational amplifier circuit AWP1, a voltage divider circuit 11, a negative feedback circuit 12, and an impedance compensation circuit 13. The voltage divider circuit 11 is connected to a signal source U1 and the non-inverting input and inverting input of the operational amplifier circuit AWP1. The voltage divider circuit 11 is used to divide the output of the signal source U1 and output voltage components to the non-inverting input and inverting input of the operational amplifier circuit AWP1. The negative feedback circuit 12 is connected between the inverting input and output of the operational amplifier circuit AWP1. The impedance compensation circuit 13 is coupled to at least the inverting input of the operational amplifier circuit AWP1. The impedance compensation circuit 13 is used to configure the equivalent impedance of the inverting input of the operational amplifier circuit AWP1 to be infinite.

[0055] The operational amplifier circuit AWP1 includes an operational amplifier or circuitry constituting an operational amplifier. The signal source U1 can be the power supply voltage signal on the sampled line or the voltage signal at the sampling node. The non-inverting input terminal and input circuit 10 of the operational amplifier circuit AWP1 are used to connect to the sampling node or sampling resistor. The operational amplifier circuit AWP1 and the negative feedback circuit 12 constitute the main components of the differential amplifier.

[0056] Impedance compensation circuit 13 configures the equivalent impedance of the inverting input terminal of operational amplifier circuit AWP1 to infinity, fixing the input impedance of the inverting input terminal under different sampling voltages. A single operational amplifier circuit AWP1 completes the voltage acquisition of the measured signal and the isolation between the measured signal and subsequent circuits, improving the sampling accuracy of the voltage sampling circuit.

[0057] For example, if the gain of the differential amplifier is set to 1, then the sampling coefficient (i.e., the amplification factor or gain) of the voltage sampling circuit mainly depends on the voltage divider resistor at the non-inverting input of the operational amplifier circuit AWP1, and is independent of the impedance of the inverting input port and the input signal. This simplifies the gain design of the voltage sampling circuit. Furthermore, since the input impedance of the inverting input is fixed under different sampling voltages, the gain consistency of the voltage sampling circuit is good across the entire input voltage range.

[0058] In the technical solution of this application embodiment, the voltage sampling circuit sets the equivalent impedance of the inverting input terminal of the operational amplifier circuit AWP1 to infinity by setting the impedance compensation circuit 13, fixing the input impedance of the inverting input terminal under different sampling voltages, greatly reducing the influence of the resistance coefficient of the input front end, greatly improving the sampling accuracy of the voltage sampling circuit, and achieving good consistency of sampling amplification gain across the entire input voltage range.

[0059] For example, the output of the operational amplifier circuit AWP1 is also connected to a grounded output resistor R9.

[0060] Please see Figure 2 In some embodiments, the voltage divider circuit 11 includes a first voltage divider network 111. The input terminal of the first voltage divider network 111 is used to connect to the signal source U1, and the output terminal of the first voltage divider network 111 constitutes the output terminal of the voltage divider circuit 130, which is connected to the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit AWP1.

[0061] In the technical solution of this application embodiment, a voltage divider network is used to divide the signal source U1 to obtain a voltage component U2, which is then applied to the non-inverting input terminal and input circuit of the operational amplifier circuit AWP1.

[0062] Please continue reading. Figure 2 In some embodiments, the first voltage divider network 111 includes a first voltage divider R2 and a second voltage divider R3. The first end of the first voltage divider R2 constitutes the input end of the first voltage divider network 111, and the second end of the first voltage divider R2 is connected to the first end of the second voltage divider R3 to constitute the output end of the first voltage divider network 111. The second end of the second voltage divider R3 is grounded.

[0063] In the technical solution of this application embodiment, during the application of the voltage sampling circuit, the first voltage divider R2 and / or the second voltage divider R3 can be set as sampling resistors in the corresponding lines.

[0064] Please see Figure 3 In some embodiments, the voltage divider circuit 130 includes a first voltage divider network 111 and a second voltage divider network 112. The input terminal of the first voltage divider network 111 is used to connect to the signal source U1, and the output terminal of the first voltage divider network 111 constitutes the first output terminal of the voltage divider circuit 130, which is connected to the inverting input terminal of the operational amplifier circuit AWP1. The input terminal of the second voltage divider network 112 is used to connect to the signal source U1, and the output terminal of the second voltage divider network 112 constitutes the second output terminal of the voltage divider circuit 130, which is connected to the non-inverting input terminal of the operational amplifier circuit AWP1.

[0065] In the technical solution of this application embodiment, two voltage divider networks are used to divide the signal source U1 to obtain two voltage components U3 and U5, which are then applied to the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit AWP1, respectively. It is understood that when the voltage division ratios of the two voltage divider networks are the same, the voltage values ​​of the two voltage components U3 and U5 are the same.

[0066] In the technical solution of this application embodiment, the sampling device or sampling node can be set in the first voltage divider network 111 and / or the second voltage divider network 112. The two grounding terminals of the first voltage divider network 111 and the second voltage divider network 112 are respectively grounded, and there are two grounding points. If either the first voltage divider network 111 or the second voltage divider network 112 fails, such as short circuit or open circuit, it will not damage the subsequent circuit. There is no risk of damage to the voltage sampling circuit, and the reliability is high compared with traditional circuits.

[0067] Please continue reading. Figure 4 In some embodiments, the first voltage divider network 111 includes a first voltage divider R2 and a second voltage divider R3. The first end of the first voltage divider R2 constitutes the input end of the first voltage divider network 111, and the second end of the first voltage divider R2 is connected to the first end of the second voltage divider R3 to constitute the output end of the first voltage divider network 111. The second end of the second voltage divider R3 is grounded.

[0068] The second voltage divider network 112 includes a third voltage divider R4 and a fourth voltage divider R5. The first end of the third voltage divider R4 forms the input end of the second voltage divider network 112. The second end of the third voltage divider R4 and the first end of the fourth voltage divider R5 are connected to form the output end of the second voltage divider network 112. The second end of the fourth voltage divider R5 is grounded.

[0069] Please continue reading. Figure 3In some embodiments, the voltage sampling circuit further includes a fifth voltage divider R1, the first end of which is connected to the positive terminal of the power supply, and the second end of which is connected to the input terminal of the first voltage divider network 111 and the input terminal of the second voltage divider network 112. The signal source U1 includes the positive terminal of the power supply.

[0070] In the technical solution of this application embodiment, during the application of the voltage sampling circuit, the third voltage divider R4 and / or the fourth voltage divider R5 can be set as sampling resistors in the corresponding lines. It can be understood that the ratio of the first voltage divider R2 to the second voltage divider R3 is a first ratio, and the ratio of the third voltage divider R4 to the fourth voltage divider R5 is a second ratio, and the first ratio and the second ratio are equal.

[0071] In addition, the first voltage divider R2, the second voltage divider R3, the third voltage divider R4 and the fourth voltage divider R5 have two grounding points. If any voltage divider fails, such as short circuit or open circuit, it will not damage the subsequent circuits and there is no risk of damage to the voltage sampling circuit. Compared with traditional circuits, it has high reliability.

[0072] It is understood that the first voltage divider R2, the second voltage divider R3, the third voltage divider R4 and the fourth voltage divider R5 are voltage divider circuits 130 composed of one or more of the following: resistive devices, capacitors, inductors, etc.

[0073] Please see Figure 3 In some embodiments, the output of the impedance compensation circuit 13 and the input impedance circuit R10, and the voltage divider circuit 11 are connected to the inverting input of the operational amplifier AWP1 and the negative feedback circuit 12 through the input impedance circuit R10. The output of the voltage divider circuit 11 is also connected to the non-inverting input of the operational amplifier AWP1. The voltage divider circuit 11 is used to output the voltage components with the same voltage value to the non-inverting input of the operational amplifier AWP1 and the input impedance circuit R10.

[0074] In one embodiment, see Figure 2 The voltage divider circuit 11 can simultaneously output the voltage component U2 to the non-inverting input terminal of the operational amplifier circuit AWP1 and the input impedance circuit R10. In another embodiment, see... Figure 3 The voltage divider circuit 11 can output voltage components U3 and U5 with equal voltage values ​​to the non-inverting input terminals of the input impedance circuit R10 and the operational amplifier circuit AWP1, respectively.

[0075] The input impedance circuit R10 includes a circuit composed of at least one of the following: resistor, capacitor, and inductor. Figure 3 In the example, the input impedance circuit R10 includes a resistor.

[0076] Voltage divider circuit 11 is used to divide the voltage based on signal source U1 to obtain voltage components, which are then provided to the non-inverting and inverting input terminals of operational amplifier circuit AWP1 (through input circuit R10). It can be understood that the sampling resistor or sampling node can be set in voltage divider circuit 130, that is, the sampling circuit can be multiplexed as impedance compensation circuit 13, making the overall circuit structure simple.

[0077] In the technical solution of this application embodiment, the voltage divider circuit 130 divides the voltage based on the signal source U1 to obtain one voltage component or two equal voltage components, which are respectively input to the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit AWP1. Based on the negative feedback virtual short characteristic of the operational amplifier circuit AWP1, the voltages at the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit AWP1 are made equal, so that the voltages across the input circuit R10 are equal and there is no voltage difference, that is, no current flows through the input circuit R10, so that the equivalent impedance of the inverting input terminal of the operational amplifier circuit AWP1 is infinite. The purpose is to transmit the voltage component applied to the input circuit R10 as a sampling signal to the output of the operational amplifier circuit AWP1 without attenuation.

[0078] Please continue reading. Figure 3 Specifically, the input impedance of the non-inverting input terminal of the operational amplifier circuit AWP1 is:

[0079]

[0080] The input impedance of the inverting input terminal of the operational amplifier circuit AWP1:

[0081]

[0082] The above analysis shows that the input impedances of the non-inverting and inverting input terminals of the operational amplifier circuit AWP1 differ. The input impedance of the non-inverting input is related to the third voltage divider R4 and the fourth voltage divider R5, while the input impedance of the inverting input is related to both the voltage component U3 and the voltage component U4 input to the inverting input. Therefore, the input impedance of the inverting input varies significantly under different sampling voltages (i.e., voltage components U3 and U5), which greatly affects the front-end resistance coefficient of the operational amplifier circuit AWP1. Therefore, compensation for the input impedance of the inverting input is necessary.

[0083] According to Ohm's law, the input current I2 is:

[0084]

[0085] Setting I2 = 0 can compensate for the input impedance Rin1 at the inverting input terminal of the operational amplifier circuit AWP1 to infinity. Since the operational amplifier circuit AWP1 is in a negative feedback operating state and has virtual short characteristics, U4≈U5.

[0086]

[0087] Therefore, the input impedance of the inverting input terminal can be compensated by configuring the resistance values ​​of the first voltage divider R2, the second voltage divider R3, the third voltage divider R4, and the fourth voltage divider R5 so that the voltage division coefficient k1 = k2.

[0088] In the technical solution of this application embodiment, another implementation concept of impedance compensation circuit 13 is provided. Voltage divider circuit 11 can use one voltage divider network 111 or two voltage divider networks 111, 112 to divide the output of signal source U1 to obtain a voltage component U2 or two voltage components U3, U5 with the same voltage value. At the same time, it is applied to the non-inverting input terminal and the input impedance circuit of operational amplifier circuit AWP1. Based on the negative feedback virtual short characteristic of operational amplifier circuit AWP1, the voltages of the non-inverting input terminal and the inverting input terminal of operational amplifier circuit AWP1 are made equal, so that the voltages across the input impedance circuit R10 are equal and no current flows through the input impedance circuit R10, thereby achieving the purpose of the equivalent impedance of the inverting input terminal of operational amplifier circuit AWP1 being infinite.

[0089] Please see Figure 4 , 5 , Figure 4 The diagram shows the simulated waveform of the theoretical gain of a conventional differential amplifier circuit across the entire input range of 0–3kV. The theoretical gain of the conventional differential amplifier circuit varies considerably across the entire input range of 0–3kV, ranging from 1.0000016 to 1.6446993, and the gain jumps by 64% at low voltage, resulting in lower measurement accuracy at low voltage. Figure 5 The diagram shown is a simulated waveform of the theoretical gain of the differential amplifier circuit of the voltage sampling circuit provided in this embodiment of the application, covering the entire input range of 0-3kV. It can be seen that the theoretical gain of the voltage sampling circuit provided in this embodiment of the application is stably maintained at approximately 99.99975% across the entire input range of 0-3kV, demonstrating good stability and high low-voltage sampling accuracy.

[0090] Please see Figure 6 , 7 , Figure 6 The diagram shown is a simulation of a Monte Carlo analysis of a conventional differential amplifier circuit. The conventional differential amplifier circuit has an output error accuracy of ±0.25% after 3000 Monte Carlo analyses. Figure 7The diagram shown is a simulation of the Monte Carlo analysis of the voltage sampling circuit provided in the embodiment of this application. The voltage sampling circuit provided in the embodiment of this application has a ±0.1% output error accuracy after 3000 Monte Carlo analyses, indicating high voltage sampling accuracy.

[0091] Please refer to the figure. Figure 3 and Figure 8 In some embodiments, the impedance compensation circuit 13 includes an input impedance circuit R10. The first end of the input impedance circuit R10 is connected to the output end of the voltage divider circuit 11, and the second end of the input impedance circuit R10 is connected to the inverting input end of the operational amplifier circuit AWP1 and the negative feedback circuit 12. The impedance of the input impedance circuit R10 is equal to the impedance of the negative feedback circuit 12.

[0092] The input impedance circuit R10 includes a circuit composed of at least one of the following: resistor, capacitor, and inductor. Figure 3 , Figure 8 In the example, the input impedance circuit R10 includes a resistor. The negative feedback circuit 12 includes a circuit composed of at least one of the following: resistor, capacitor, and inductor. Figure 3 , Figure 8 In the example, the negative feedback circuit 12 includes a resistor R8.

[0093] exist Figure 8 In the example, based on the virtual short characteristic of the operational amplifier circuit AWP1, U3 = U4 = U2.

[0094] When only the inverting input of the operational amplifier circuit AWP1 is considered, the partial output of the operational amplifier circuit AWP1 is Uo1 = U2 * (-R8 / R10).

[0095] When only the non-inverting input of the operational amplifier circuit AWP1 is considered, the other part of the output of the operational amplifier circuit AWP1 is Uo2 = U2 * ((R10 + R8) / R10).

[0096] Therefore, the total output of the operational amplifier circuit AWP1 is Uo = Uo1 + Uo2. Let the resistance of the input impedance circuit R10 be equal to the resistance of the negative feedback circuit 12, then the total output of the operational amplifier circuit AWP1 will be Uo = U2.

[0097] Since U2 = U4, there is no current in the input impedance circuit R10, which is equivalent to the inverting input impedance of the operational amplifier circuit AWP1 being infinite. The simulation results are consistent with... Figures 4 to 7 Similar to each other, they can also achieve high-precision sampling requirements.

[0098] In the technical solution of this application embodiment, another embodiment of impedance compensation circuit 13 is provided. When the resistance value of input impedance circuit R10 is equal to the resistance value of negative feedback circuit 12, based on the negative feedback virtual short characteristic of operational amplifier circuit AWP1, the voltages of non-inverting input terminal and inverting input terminal of operational amplifier circuit AWP1 are made equal, so that the voltages across input impedance circuit R10 are equal and no current flows through input impedance circuit R10, thereby achieving the purpose of the equivalent impedance of inverting input terminal of operational amplifier circuit AWP1 being infinite.

[0099] Please see Figure 9 In some embodiments, the impedance compensation circuit 13 includes a current suppression component 131 and an input impedance circuit R10. The first end of the current suppression component 131 is connected to the output end of the voltage divider circuit 11, and the second end of the current suppression component 131 is connected to the inverting input end of the operational amplifier circuit AWP1 and the negative feedback circuit 12 through the input impedance circuit R10. The current suppression component 131 is used to suppress the current flowing through the input impedance circuit R10.

[0100] In the technical solution of this application embodiment, another implementation concept of impedance compensation circuit 13 is provided. The current suppression component 131 suppresses the current flowing through the input impedance circuit R10, which can also achieve the purpose of making the equivalent impedance of the inverting input terminal of the operational amplifier circuit AWP1 infinite.

[0101] Please continue reading. Figure 9 In some embodiments, the current suppression component 122 includes two diodes D1 and D2, which are connected in series in opposite phases with common anodes at the first end of the input impedance circuit R10.

[0102] In the technical solution of this application embodiment, the common anode of the two diodes D1 and D2 can suppress the current flowing through the input impedance circuit R10, so as to achieve the purpose of making the equivalent impedance of the inverting input terminal of the operational amplifier circuit AWP1 infinite.

[0103] Please see Figure 10 , Figure 10 The output deviation of the voltage sampling circuit is shown. The green waveform represents the voltage sampling circuit with current suppression component 131, and the blue waveform represents the voltage sampling circuit without current suppression component 131. The simulation results show that the circuit with current suppression component 12 has a smaller sampling bias and higher sampling accuracy.

[0104] In some embodiments, to ensure the high-precision operation of the operational amplifier circuit AWP1, it is necessary to compensate for the voltage offset caused by the bias current of AWP1, so that AWP1 operates within the expected accuracy range. Without compensation, the different resistances at the non-inverting and inverting input terminals, observed from the input ports of AWP1, result in larger bias voltages caused by the bias currents at these terminals. This leads to significant deviations in the output of AWP1, ultimately reducing the voltage sampling rate.

[0105] Please see Figure 11 In some embodiments, the voltage sampling circuit further includes a bias current compensation circuit 14, which is coupled to at least one of the non-inverting input and the inverting input of the operational amplifier circuit AWP1. The bias current compensation circuit 14 is used to configure the external equivalent resistance of the non-inverting input of the operational amplifier circuit AWP1 to be equal to the external equivalent resistance of the inverting input of the operational amplifier circuit AWP1.

[0106] Among them, the bias current compensation circuit 14 is based on the external equivalent resistance of the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit AWP1, which is matched with the circuit parameters. It can also be regarded as the input circuit / impedance of the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit AWP1.

[0107] In the technical solution of this application embodiment, the bias current compensation circuit 14 makes the external equivalent resistance connected to the non-inverting input terminal of the operational amplifier circuit AWP1 equal to the external equivalent resistance connected to the inverting input terminal of the operational amplifier circuit AWP1, thereby reducing the influence of the bias current and offset voltage of the operational amplifier circuit AWP1, realizing bias current compensation of the operational amplifier circuit AWP1, and reducing the influence of the bias current of the input port on the calculation results.

[0108] Please see Figure 3 and Figure 8 In some embodiments, the bias current compensation circuit 14 includes a first compensation resistor R7, which is coupled to the non-inverting input of the operational amplifier circuit AWP1.

[0109] The first compensation resistor R7 can be connected to the non-inverting input of the operational amplifier circuit AWP1 in parallel (i.e., one end of the first compensation resistor R7 is connected to the non-inverting input of the operational amplifier circuit AWP1, and the other end is grounded) or in series, depending on the specific situation. For example, if the external equivalent resistance connected to the non-inverting input of the operational amplifier circuit AWP1 is greater than the external equivalent resistance connected to the inverting input of the operational amplifier circuit AWP1, then the first compensation resistor R7 is connected in parallel with the non-inverting input of the operational amplifier circuit AWP1; otherwise, it is connected in series.

[0110] In the technical solution of this application embodiment, when the external equivalent resistance connected to the non-inverting input terminal of the operational amplifier circuit AWP1 is not equal to the external equivalent resistance connected to the inverting input terminal of the operational amplifier circuit AWP1, compensation can be made by the first compensation resistor R7 coupled to the non-inverting input terminal of the operational amplifier circuit AWP1, so that the external equivalent resistance connected to the non-inverting input terminal of the operational amplifier circuit AWP1 is equal to the external equivalent resistance connected to the inverting input terminal of the operational amplifier circuit AWP1.

[0111] Please see Figure 3 and Figure 8 In some embodiments, the bias current compensation circuit 14 further includes a second compensation resistor R6, which is coupled to the inverting input terminal of the operational amplifier circuit AWP1.

[0112] The second compensation resistor R6 can be connected to the inverting input of the operational amplifier circuit AWP1 in parallel (i.e., one end of the second compensation resistor R6 is connected to the inverting input of the operational amplifier circuit AWP1, and the other end is grounded) or in series, depending on the specific situation. For example, if the external equivalent resistance connected to the inverting input of the operational amplifier circuit AWP1 is greater than the external equivalent resistance connected to the non-inverting input of the operational amplifier circuit AWP1, then the second compensation resistor R6 is connected in parallel with the inverting input of the operational amplifier circuit AWP1; otherwise, it is connected in series.

[0113] In the technical solution of this application embodiment, when the external equivalent resistance connected to the non-inverting input terminal of the operational amplifier circuit AWP1 is not equal to the external equivalent resistance connected to the inverting input terminal of the operational amplifier circuit AWP1, it can be compensated by the first compensation resistor R7 and / or the second compensation resistor R6, so that the external equivalent resistance connected to the non-inverting input terminal of the operational amplifier circuit AWP1 is equal to the external equivalent resistance connected to the inverting input terminal of the operational amplifier circuit AWP1.

[0114] For example, please continue reading Figure 3 :

[0115] Rin-=R7+(R8+R9) / / (R10+(R3 / / (R1+R2)))

[0116] Rin+=R6+(R5 / / (R4+(R1 / / (R2+R3))))

[0117] Wherein, Rin- is the equivalent resistance viewed from the inverting input terminal of the operational amplifier circuit AWP1 to the outside, and Rin+ is the equivalent resistance viewed from the non-inverting input terminal of the operational amplifier circuit AWP1 to the outside.

[0118] Depending on the different amplifier circuit resistance configurations, adjusting the first compensation resistor R7 and the second compensation resistor R6 to make Rin- equal to Rin+ will complete the bias current compensation of the operational amplifier circuit AWP1.

[0119] Since the input impedance of the inverting input terminal of the operational amplifier circuit AWP1 is infinite, the gain of the voltage sampling circuit is configured by both the resistor voltage divider and the differential amplifier circuit. Therefore, the gain of the voltage sampling circuit can be expressed by the following formula.

[0120]

[0121] For ease of design, we can usually let R8 / R10 = R5 / R4, then the above formula can be simplified to:

[0122]

[0123] For ease of design, we can let R8 = R10 = R5 = R4, then the above formula can be further simplified to:

[0124]

[0125] For example, the circuit design has an amplification gain of G1 = 1 / 1000, and the calculated first compensation resistor R7 = 1.375kΩ and the second compensation resistor R6 = 0.8kΩ.

[0126] Secondly, embodiments of this application provide an electronic device including at least one voltage sampling circuit as described above.

[0127] In the technical solutions of this application embodiment, the use of two or more voltage sampling circuits in the electronic device ensures the accuracy of sampling to a greater extent.

[0128] For example, in the field of high-voltage cascaded energy storage, precise sampling of the energy storage valve submodule and even the battery voltage is required. Furthermore, due to the high voltage of high-voltage energy storage, in conventional topologies, the failure of a resistor in the voltage divider circuit can damage downstream boards, thereby affecting the safety and reliability of the entire system. However, in the electronic device of this application embodiment, the voltage divider circuit 130 has two grounding points. A single grounding failure will not damage the downstream boards. Compared to traditional circuits, the electronic device of this application embodiment has higher reliability.

[0129] In some embodiments, damage to the voltage divider circuit 130 can also affect sampling accuracy. To ensure high reliability in applications, a two-out-of-three circuit is constructed based on the aforementioned high-precision voltage sampling circuit. This means that three voltage sampling circuits are used simultaneously for each sampling node. If one of the voltage sampling circuits fails and has a large sampling error, the three sampled values ​​are compared, and the two sets of data with similar values ​​are selected, thus ensuring greater sampling accuracy.

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A voltage sampling circuit, characterized in that, The system includes an operational amplifier circuit, a voltage divider circuit, a negative feedback circuit, and an impedance compensation circuit. The voltage divider circuit is connected to a signal source, the non-inverting input terminal of the operational amplifier circuit, and the inverting input terminal. The voltage divider circuit is used to divide the output of the signal source and output voltage components to the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit. The negative feedback circuit is connected between the inverting input terminal and the output terminal of the operational amplifier circuit. The impedance compensation circuit is coupled to at least the inverting input terminal of the operational amplifier circuit and is used to configure the equivalent impedance of the inverting input terminal of the operational amplifier circuit to be infinite.

2. The voltage sampling circuit according to claim 1, characterized in that, It also includes a bias current compensation circuit, which is coupled to at least one of the non-inverting input terminal and the inverting input terminal of the operational amplifier circuit. The bias current compensation circuit is used to configure the external equivalent resistance of the non-inverting input terminal of the operational amplifier circuit to be equal to the external equivalent resistance of the inverting input terminal of the operational amplifier circuit.

3. The voltage sampling circuit according to claim 2, characterized in that, The bias current compensation circuit includes a first compensation resistor, which is coupled to the non-inverting input terminal of the operational amplifier circuit.

4. The voltage sampling circuit according to claim 2 or 3, characterized in that, The bias current compensation circuit includes a second compensation resistor, which is coupled to the inverting input terminal of the operational amplifier circuit.

5. The voltage sampling circuit according to claim 1, characterized in that, The voltage divider circuit includes a first voltage divider network, the input terminal of which is used to connect to the signal source, and the output terminal of the first voltage divider network constitutes the output terminal of the voltage divider circuit.

6. The voltage sampling circuit according to claim 1, characterized in that, The voltage divider circuit includes a first voltage divider network and a second voltage divider network. The input terminal of the first voltage divider network is used to connect to the signal source, and the output terminal of the first voltage divider network constitutes the first output terminal of the voltage divider circuit and is connected to the inverting input terminal of the operational amplifier circuit. The input terminal of the second voltage divider network is used to connect to the signal source, and the output terminal of the second voltage divider network constitutes the second output terminal of the voltage divider circuit and is connected to the non-inverting input terminal of the operational amplifier circuit.

7. The voltage sampling circuit according to claim 5 or 6, characterized in that, The first voltage divider network includes a first voltage divider and a second voltage divider. The first end of the first voltage divider constitutes the input end of the first voltage divider network. The second end of the first voltage divider is connected to the first end of the second voltage divider to constitute the output end of the first voltage divider network. The second end of the second voltage divider is grounded.

8. The voltage sampling circuit according to claim 6, characterized in that, The second voltage divider network includes a third voltage divider and a fourth voltage divider. The first end of the third voltage divider forms the input end of the second voltage divider network. The second end of the third voltage divider is connected to the first end of the fourth voltage divider to form the output end of the second voltage divider network. The second end of the fourth voltage divider is grounded.

9. The voltage sampling circuit according to claim 6, characterized in that, The voltage divider circuit further includes a fifth voltage divider, the first end of which is connected to the positive terminal of the power supply, and the second end of which is connected to the input terminal of the first voltage divider network and the input terminal of the second voltage divider network. The signal source includes the positive terminal of the power supply.

10. The voltage sampling circuit according to any one of claims 1 to 9, characterized in that, The impedance compensation circuit includes an input impedance circuit. The first end of the input impedance circuit is connected to the output end of the voltage divider circuit, and the second end of the input impedance circuit is connected to the inverting input end of the operational amplifier circuit and the negative feedback circuit. The impedance of the input impedance circuit is the same as the impedance of the negative feedback circuit.

11. The voltage sampling circuit according to any one of claims 1 to 9, characterized in that, The impedance compensation circuit includes a current suppression component and an input impedance circuit. The first end of the current suppression component is connected to the output end of the voltage divider circuit, and the second end of the current suppression component is connected to the inverting input end of the operational amplifier circuit and the negative feedback circuit through the input impedance circuit. The current suppression component is used to suppress current from flowing through the input impedance circuit.

12. The voltage sampling circuit according to claim 11, characterized in that, The current suppression component includes two diodes that are common anode and connected in reverse series at the first terminal of the input impedance circuit.

13. The voltage sampling circuit according to any one of claims 1 to 9, characterized in that, The impedance compensation circuit includes the voltage divider circuit and the input impedance circuit. The output terminal of the voltage divider circuit is connected to the inverting input terminal of the operational amplifier and the negative feedback circuit through the input impedance circuit. The output terminal of the voltage divider circuit is also connected to the non-inverting input terminal of the operational amplifier circuit. The voltage divider circuit is used to output the voltage components with the same voltage value to the non-inverting input terminal of the operational amplifier circuit and the input impedance circuit.

14. An electronic device, characterized in that, It includes at least one voltage sampling circuit as described in any one of claims 1 to 13.

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