High-precision measuring device for high voltage

Abstract

A high-precision measuring device for high voltage mainly comprises a high-voltage attenuation and input protection module, a differential input and signal conditioning module and a high-precision measuring and processing module which are connected in sequence, and the high-voltage attenuation and input protection module is used for attenuating an input direct-current high-voltage signal to a low-voltage range capable of being processed by a subsequent circuit according to a preset proportion; the differential input and signal conditioning module is used for identifying and extracting a differential-mode voltage signal, namely an effective signal, between the two input ends, and greatly suppressing common-mode noise of the two input ends at the same time; and the high-precision measuring and processing module converts the differential analog signal into a single-ended signal through pre-stage conditioning, firstly performs high-precision voltage measurement, then performs analog-to-digital conversion, and finally uploads the single-ended signal to the processor through noise isolation. According to the device, a graded and reliable safety protection and anti-interference system is constructed, high-precision measurement of high voltage can be realized, and the highest 7.5-bit high-voltage measurement precision can be realized.

Description

Technical Field

[0001] This invention relates to the field of high voltage signal testing and measurement technology, and in particular to a high-precision high-voltage measuring device. Background Technology

[0002] In existing technologies, with the increasing demands for high-voltage DC power supply performance in fields such as new energy and semiconductors, the need for high-precision measurement of kilovolt-level high voltage is growing, with measurement accuracy requirements even reaching 7.5 digits. However, currently available measuring instruments struggle to simultaneously maintain measurement accuracy and stability under high voltage conditions and with a large dynamic range, failing to meet the ever-increasing demand for integrated high-voltage and high-precision testing. Summary of the Invention

[0003] To address the limitations of existing technologies in terms of limited voltage measurement range and insufficient measurement accuracy, this disclosure provides a high-voltage, high-precision measurement circuit with high-voltage DC protection. This circuit employs a core architecture combining a high-voltage attenuation resistor and a differential input, achieving both safe attenuation and input protection for kilovolt-level high-voltage signals, and effectively suppressing common-mode interference. This significantly improves the overall voltage withstand capability and anti-interference performance of the system while broadening the measurement range, meeting the high-precision measurement requirements under high-voltage environments.

[0004] Its core design concept lies in first setting a high-performance high-voltage attenuation resistor network at the input of the measurement circuit. This attenuation resistor network plays a crucial role in current limiting and voltage division, safely and linearly attenuating the input DC high-voltage signal, which is as high as several kilovolts, to a low-voltage range that subsequent circuits can handle according to a predetermined ratio. This creates a first robust barrier at the physical level, effectively avoiding the risk of high-voltage breakdown or overload, and playing a vital role in protecting the subsequent precision voltage measurement units (such as high-resolution analog-to-digital converters).

[0005] The attenuated low-voltage signal does not directly enter the core measurement unit, but is instead connected to the differential input unit. This unit employs a symmetrical circuit architecture with a high common-mode rejection ratio (CMRR), capable of identifying and extracting the differential-mode voltage signal (i.e., the useful signal) between the two input terminals, while significantly suppressing identical common-mode noise (typically originating from ground loops, spatial electromagnetic coupling, etc.) on both input terminals. This design greatly eliminates common-mode interference superimposed on the signal lines in complex electromagnetic measurement environments, thereby ensuring the purity and integrity of the measured voltage signal.

[0006] By organically combining the two core technologies of "high voltage attenuation protection" and "differential noise suppression", this disclosure not only safely expands the voltage measurement range, but also significantly improves the signal measurement accuracy and system stability in high noise background, fundamentally solving the problem that traditional methods cannot achieve both high voltage and high precision.

[0007] Specifically, this disclosure provides a high-voltage, high-precision measuring device, which mainly includes: a high-voltage attenuation and input protection module, a high-voltage attenuation and input protection module, and a high-precision measurement and processing module connected in sequence, wherein: The high-voltage attenuation and input protection module, the differential input and signal conditioning module, and the high-precision measurement and processing module are connected in sequence, among which: The high voltage attenuation and input protection module is used to attenuate the input DC high voltage signal to a low voltage range that can be processed by subsequent circuits according to a predetermined ratio. The differential input and signal conditioning module is used to identify and extract the differential voltage signal, i.e., the effective signal, between the two input terminals, while significantly suppressing the common-mode noise of the two input terminals. The high-precision measurement and processing module converts the differential analog signal into a single-ended signal through pre-conditioning, performs high-precision voltage measurement, then performs analog-to-digital conversion, and finally uploads the signal to the processor through noise isolation.

[0008] Furthermore, the high voltage attenuation and input protection module includes: a resistor divider network and a back-end protection unit, wherein: The resistor voltage divider network includes two sets of resistor attenuation networks composed of multiple high-precision high-voltage resistors connected in series. The two sets of networks correspond to the positive and negative input ends of the high voltage, respectively, and are used to convert the input high voltage into a low voltage signal proportionally through the voltage division effect of the resistors. Back-end protection unit: Located between the output terminals of the resistor divider network, it uses bidirectional Zener diodes for voltage monitoring and transient overvoltage clamping protection of the differential input terminal in case of voltage divider circuit failure or high voltage intrusion.

[0009] Furthermore, the attenuation ratio of the voltage divider network is 500:1.

[0010] Furthermore, in the differential input and signal conditioning module, the positive and negative low-voltage terminals output by the high-voltage attenuation and input protection module are connected to the non-inverting and inverting input terminals of the zero-drift amplifier, respectively, to convert the original high-voltage differential signal into a low-voltage single-ended signal with signal ground as the reference. In addition, by configuring the external gain resistor of the precision amplifier, the attenuated signal is precisely amplified so that its amplitude matches the input range of the subsequent ADC.

[0011] Furthermore, the high-precision measurement and processing module includes: The analog-to-digital conversion section is used to sample and digitize the differential analog signal after pre-conditioning; it includes a digital filter to suppress power frequency noise. The MCU microprocessor is used to perform nonlinear correction of data and temperature drift compensation of signals, and to amplify the measured low voltage value to obtain the original high voltage value; the measurement results are output through an isolation interface. Between the analog-to-digital conversion section and the microprocessor, there is an isolated SPI communication channel constructed from a high-speed optocoupler chip, which is used to cut off the ground loop and prevent high-voltage noise from the front end from coupling to the digital system.

[0012] Furthermore, the analog-to-digital conversion section employs a high-resolution, low-noise Σ-Δ ADC.

[0013] Compared with the prior art, the beneficial effects of this disclosure are: ① achieving high resolution and high precision measurement under high voltage input conditions; ② constructing a hierarchical and reliable safety protection and anti-interference system; ③ providing a highly versatile and easily integrated circuit implementation scheme. Attached Figure Description

[0014] The above and other objects, features and advantages of this disclosure will become more apparent from the more detailed description of exemplary embodiments of this disclosure taken in conjunction with the accompanying drawings, in which the same reference numerals generally represent the same components.

[0015] Figure 1 This is a block diagram illustrating the overall principle of the high-voltage, high-precision measurement circuit according to this disclosure; Figure 2 This is a block diagram illustrating the principle of the high-voltage attenuation unit. Figure 3 This is a block diagram illustrating the principle of the differential measurement unit. Figure 4 This is a block diagram of the voltage detection unit. Detailed Implementation

[0016] Preferred embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0017] This disclosure provides a solution for high-precision measurement of high voltage.

[0018] In one exemplary implementation: like Figure 1 As shown, in the precision measurement design under high voltage environment, the high voltage precision measurement system according to this disclosure mainly consists of three core modules: The high voltage attenuation and input protection module uses multiple high-precision high voltage resistors connected in series to form a 500:1 voltage divider network, which linearly attenuates the ±5kV input to ±10V, and uses bidirectional Zener diodes to provide transient overvoltage clamping protection for the differential input terminal of the subsequent stage. The differential input and signal conditioning module is based on a precision operational amplifier with high common-mode rejection ratio, zero drift, and ultra-low noise. It converts the attenuated differential signal into a ground-referenced single-ended signal. Its CMRR of over 160dB can effectively suppress common-mode noise, and the range of the subsequent stage is precisely matched by an external gain resistor. The high-precision measurement and processing module uses a low-noise Σ-Δ ADC for digital sampling, and its built-in filter can suppress power frequency interference. The data is transmitted to the MCU through a high-speed optocoupler-isolated SPI. After completing calibration processing such as temperature drift compensation, the data is finally uploaded through the isolation interface. This ensures high-voltage isolation safety while realizing high-voltage detection, high resolution, and high anti-interference precision measurement, achieving a maximum high-voltage measurement accuracy of 7.5 bits.

[0019] (1) such as Figure 2 As shown, the high voltage attenuation and input protection module consists of a high voltage attenuation resistor network and a Zener diode protection circuit.

[0020] In the resistor network design, multiple high-precision, high-stability high-voltage metal film resistors are connected in series to form a voltage divider. The design attenuation ratio is 500:1, which can linearly attenuate the input ±5kV high voltage to the safe operating range of ±10V for subsequent circuits. The resistor series design not only achieves the voltage division function, but also effectively distributes voltage stress and heat dissipation, significantly improving the module's withstand voltage reliability.

[0021] In terms of input protection design, a bidirectional Zener diode is connected in parallel across the differential input circuit to protect it. When an abnormally high voltage difference occurs at the input due to transient overvoltage or interference, the Zener diode can quickly conduct and clamp the voltage, limiting it to a safe range. This effectively prevents internal sensitive components from being damaged by breakdown or overload, thus improving the reliability and stability of the circuit. (2) For example Figure 3 As shown, the core of the differential input and signal conditioning module is to construct a differential amplifier circuit with high common-mode rejection ratio, zero drift, ultra-low noise, and ultra-high DC accuracy.

[0022] For signal connection, the positive and negative low-voltage terminals of the attenuation resistor network are connected to the non-inverting and inverting inputs of the zero-drift amplifier, respectively, thereby converting the original high-voltage differential signal into a low-voltage single-ended signal referenced to signal ground. This operational amplifier effectively suppresses common-mode noise such as ground fluctuations and electromagnetic induction, and its CMRR > 160dB ensures that signal purity is maintained even in environments with strong interference.

[0023] Furthermore, by configuring the external gain resistor of the precision amplifier, the attenuated signal is precisely amplified so that its amplitude matches the input range of the subsequent ADC, thereby making full use of the ADC's resolution.

[0024] Figure 3 In this differential-to-single-ended converter, two non-inverting amplifiers form a differential input buffer stage. Since the first two amplifier stages employ closed-loop negative feedback, their output voltages create a voltage difference across the three feedback resistor networks. The differential gain of the circuit can be changed by adjusting the value of R1. The subsequent differential operational amplifier acts as a subtractor; its output is the difference between the attenuated positive and negative voltages, and is affected by the gain of A3, which is determined by the ratio of R3 to R4. Ultimately, this circuit achieves the conversion from differential to single-ended signals, and the signal magnitude can be adjusted by regulating the resistors.

[0025] (3) such as Figure 4 As shown, the high-precision measurement and processing module consists of two parts: analog-to-digital conversion and isolated communication.

[0026] The analog-to-digital converter uses a high-resolution, low-noise Σ-Δ ADC to sample and digitize the differential analog signal after pre-conditioning; its built-in digital filter can effectively suppress power frequency noise.

[0027] An isolated SPI communication channel is constructed between the ADC and the microprocessor using a high-speed optocoupler chip to cut off the ground loop and prevent high-voltage noise from the front end from coupling to the digital system.

[0028] The MCU is responsible for performing nonlinear correction of the data and temperature drift compensation of the signal, and finally uploads the measurement results to the host computer through the isolation interface.

[0029] The above technical solutions are merely exemplary embodiments of the present invention. For those skilled in the art, based on the application methods and principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the methods described in the specific embodiments of the present invention. Therefore, the methods described above are merely preferred and not restrictive.

Claims

1. A high-voltage, high-precision measuring device, characterized in that, include: The high-voltage attenuation and input protection module, the differential input and signal conditioning module, and the high-precision measurement and processing module are connected in sequence, among which: The high voltage attenuation and input protection module is used to attenuate the input DC high voltage signal to a low voltage range that can be processed by subsequent circuits according to a predetermined ratio. The differential input and signal conditioning module is used to identify and extract the differential voltage signal, i.e., the effective signal, between the two input terminals, while significantly suppressing the common-mode noise of the two input terminals. The high-precision measurement and processing module converts the differential analog signal into a single-ended signal through pre-conditioning, performs high-precision voltage measurement, then performs analog-to-digital conversion, and finally uploads the signal to the processor through noise isolation.

2. The apparatus according to claim 1, characterized in that, The high voltage attenuation and input protection module includes: a resistor divider network and a back-end protection unit, wherein: The resistor voltage divider network includes two sets of resistor attenuation networks composed of multiple high-precision high-voltage resistors connected in series. The two sets of networks correspond to the positive and negative input ends of the high voltage, respectively, and are used to convert the input high voltage into a low voltage signal proportionally through the voltage division effect of the resistors. Back-end protection unit: Located between the output terminals of the resistor divider network, it uses bidirectional Zener diodes for voltage monitoring and transient overvoltage clamping protection of the differential input terminal in case of voltage divider circuit failure or high voltage intrusion.

3. The apparatus according to claim 2, characterized in that, The attenuation ratio of the voltage divider network is 500:

1.

4. The apparatus according to claim 1, characterized in that, In the differential input and signal conditioning module, the positive and negative low-voltage terminals output by the high-voltage attenuation and input protection module are connected to the non-inverting and inverting input terminals of the zero-drift amplifier, respectively, to convert the original high-voltage differential signal into a low-voltage single-ended signal with signal ground as the reference. Furthermore, by configuring the external gain resistor of the precision amplifier, the attenuated signal is precisely amplified so that its amplitude matches the input range of the subsequent ADC.

5. The apparatus according to any one of claims 1-4, characterized in that, The high-precision measurement and processing module includes: The analog-to-digital conversion section is used to sample and digitize the differential analog signal after pre-conditioning; it includes a digital filter to suppress power frequency noise. The MCU microprocessor is used to perform nonlinear correction of data and temperature drift compensation of signals, and to amplify the measured low voltage value to obtain the original high voltage value; the measurement results are output through an isolation interface. Between the analog-to-digital conversion section and the microprocessor, there is an isolated SPI communication channel constructed from a high-speed optocoupler chip, which is used to cut off the ground loop and prevent high-voltage noise from the front end from coupling to the digital system.

6. The apparatus according to claim 5, characterized in that, The analog-to-digital conversion section uses a high-resolution, low-noise Σ-Δ ADC.

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