A resistance-capacitance network voltage sensing probe

Abstract

A resistance-capacitance network voltage sensing probe relates to the technical field of voltage sensing probe. The problems of poor adaptability of oscilloscope, serious heat generation and limited applicable frequency band of voltage probe when measuring the frequency spectrum of high amplitude voltage signal are solved. The technical scheme is that: an insulating material shell is arranged, an input port for connecting the measured signal is arranged on the insulating material shell, a resistance-capacitance network voltage dividing circuit for attenuating high amplitude direct current or low frequency alternating current voltage component in the measured signal is arranged in the insulating material shell, and an output port for connecting the frequency spectrum analysis device is arranged on the insulating material shell; the resistance-capacitance network voltage dividing circuit is resistance and capacitance connected in series on the loop between the input port and the output port for pressure bearing and voltage dividing. The voltage bearing is high, the loss is small, the wide band frequency spectrum can be accurately sensed, the safety of subsequent instruments such as frequency spectrum analyzer or oscilloscope is ensured, and the energy loss and thermal noise are reduced.

Description

Technical Field

[0001] This utility model relates to the field of electrical and electronic measurement products, specifically to the field of voltage sensing probe technology. Background Technology

[0002] Currently, the spectrum measurement of high-voltage amplitude signals in electrical switches and power electronic equipment typically involves using an oscilloscope to acquire time-domain waveforms and then performing a Fast Fourier Transform (FFT) to calculate the spectrum. However, this method is only suitable for measuring low-order frequencies. When the harmonic order of interest is high, the oscilloscope may fail to accurately calculate the spectrum due to errors in the sampling amplitude. Some voltage probes use a series resistor network to attenuate the high-amplitude voltage signal before measuring the spectrum with a spectrum analyzer. However, this type of probe suffers from problems such as significant resistor heating and limited applicable bandwidth. Therefore, it is necessary to design a voltage sensing probe that can withstand high-amplitude voltages, has low loss, and can measure the spectrum over a wide bandwidth. Utility Model Content

[0003] In summary, the purpose of this invention is to solve the problems of poor adaptability of oscilloscopes and the serious overheating and limited applicable frequency band of voltage probes when measuring the spectrum of high-amplitude voltage signals, and to propose a resistor-capacitor network voltage sensing probe.

[0004] To solve the technical problem proposed by this utility model, the technical solution adopted is as follows:

[0005] A voltage sensing probe composed of a resistor-capacitor network includes an insulating material shell, an input port on the insulating material shell for receiving the signal to be measured, a resistor-capacitor network voltage divider circuit inside the insulating material shell for attenuating high-amplitude DC or low-frequency AC voltage components in the signal to be measured, and an output port on the insulating material shell for connecting to a spectrum analysis device; the resistor-capacitor network voltage divider circuit consists of a resistor and a capacitor connected in series in the loop between the input port and the output port for voltage bearing and voltage division.

[0006] The technical solution that further defines this utility model is as follows:

[0007] The resistor-capacitor network voltage divider circuit includes two sets of resistors and capacitors connected in series, which are respectively connected to the two poles between the input port and the output port.

[0008] The two sets of resistors and capacitors in series are symmetrically installed on the same side or both sides of the same insulating board.

[0009] The input port and output port are respectively located at opposite ends of the insulating material shell.

[0010] The input port is a parallel cable interface or a coaxial cable interface.

[0011] The output port is a two-core parallel cable interface, an SMA or N-type coaxial connector, or a coaxial cable structure.

[0012] The insulating substrate is a printed circuit board, a ceramic substrate, or a flexible material substrate.

[0013] The capacitance value of the capacitor in the resistor-capacitor network voltage divider circuit is less than 5 pF.

[0014] The beneficial effects of this invention are as follows: When this invention is used for spectrum measurement of the operating voltage of power semiconductor devices in electrical switches and power electronic equipment, the high-amplitude voltage signal in the measured signal is sent to the resistor-capacitor network voltage divider circuit through the input port. The DC or low-frequency components of the input voltage are mainly supported by the capacitor, while the high-frequency components are mainly supported by the resistor. These high-frequency components are attenuated by each resistor and then sent to the output port for use by the subsequent spectrum analyzer or oscilloscope. Compared with existing voltage probe structures, this invention can achieve high voltage withstand, low loss, and accurate sensing over a wide frequency range. This invention uses capacitors to bear the high-amplitude DC or low-frequency voltage components, ensuring the safety of subsequent instruments such as spectrum analyzers or oscilloscopes, while also reducing energy loss and thermal noise. This invention uses a resistor-capacitor network to allow the passage and necessary attenuation of high-order voltage signals, achieving accurate spectrum sensing in the 10 kHz-300 MHz frequency range. This invention uses a symmetrical structural design to achieve high common-mode rejection ratio performance over a wide frequency range. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the probe of this utility model.

[0016] Figure 2 This is a schematic diagram of the measurement principle of the probe of this utility model.

[0017] Figure 3 This is a schematic diagram of one embodiment of the probe of this utility model.

[0018] Figure 4 This is a simplified schematic diagram of one embodiment of the probe of this utility model.

[0019] Figure 5 This is a schematic diagram of an asymmetric implementation of the probe of this utility model. Detailed Implementation

[0020] The technical solution of this utility model will be further described below with reference to the accompanying drawings and preferred specific embodiments.

[0021] Reference Figures 1 to 5 As shown, the present invention discloses a voltage sensing probe composed of a resistor-capacitor network, including an insulating material shell 1, an input port 3 on the insulating material shell 1 for receiving the signal to be measured, a resistor-capacitor network voltage divider circuit inside the insulating material shell 1 for attenuating high-amplitude DC or low-frequency AC voltage components in the signal to be measured, and an output port 4 on the insulating material shell 1 for connecting a spectrum analysis device; the resistor-capacitor network voltage divider circuit consists of a resistor and a capacitor connected in series in the loop between the input port 3 and the output port 4 for bearing and dividing voltage.

[0022] In other words, when this invention senses the voltage signal being measured, the resistor-capacitor network voltage divider circuit is connected to subsequent instruments such as a spectrum analyzer or oscilloscope. The input impedance of the spectrum analyzer or oscilloscope forms a voltage divider network. The input port 3 is connected to the voltage signal being measured, and the voltage signal is input to the resistor-capacitor network voltage divider circuit. The resistor-capacitor network voltage divider circuit attenuates the high-amplitude DC or low-frequency AC voltage components in the measured signal, while simultaneously sending the high-frequency components of the measured signal to the output port 4 as proportionally as possible. The output port 4 outputs the voltage signal, providing it to the spectrum analyzer, oscilloscope, and other instruments. This allows for accurate measurement of the amplitude of the measured signal in the 10 kHz-300 MHz frequency band.

[0023] In the specific implementation of this invention, the resistor-capacitor network voltage divider circuit can be adopted. Figure 5 The asymmetric structure shown can also be adopted Figure 3 and Figure 4 The symmetrical structure on both sides or the same side of the same insulating material shown in the figure introduces the resistor-capacitor network voltage divider circuit of the symmetrical structure into the voltage sensing probe, and designs the resistors in the voltage sensing probe circuit symmetrically to achieve high common mode rejection ratio performance over a wide frequency range.

[0024] Implementation Plan 1

[0025] Reference Figure 2 and Figure 3 As shown, this utility model discloses a resistor-capacitor network voltage sensing probe. The input port 3 and output port 4 are respectively located at opposite ends of the insulating material housing 1. The input port 3 can be a parallel cable interface that connects directly to a parallel cable, or it can be a coaxial cable interface that connects to a coaxial cable connector. The output port 4 preferably uses an SMA or N-type coaxial connector, through which the signal is sent to the input terminal Zin of a subsequent spectrum analyzer or oscilloscope.

[0026] The resistor-capacitor network voltage divider circuit includes two sets of resistor-capacitor series circuits, which are respectively connected to the two terminals between the input port and the output port. Each set of resistor-capacitor series circuits can consist of more than one resistor and more than one capacitor connected in series. The number of resistors and capacitors can be determined according to the voltage division requirements. The two sets of resistor-capacitor series circuits are symmetrically mounted on the upper and lower sides of the same printed circuit board to form a symmetrical structure. The printed circuit board can also be replaced with a ceramic substrate or a flexible material substrate.

[0027] In this embodiment, the transfer function of the resistor-capacitor network voltage sensing probe of this invention is as follows:

[0028]

[0029] in, Z in This is the input impedance for subsequent instruments. R This is the resistance value. C Here, n represents the capacitance value, n is the number of resistors connected in series on one side, and m is the number of capacitors connected in series on one side. ω Angular frequency, j It is the imaginary unit.

[0030] The specific values ​​of the capacitor and resistor can be selected as follows: the capacitance C should be much smaller than the source-drain capacitance C of the power switch transistor. oss If the value can be taken as 2 pF, and the total value of the series resistance of the resistor-capacitor network can be taken as 200 Ω, then the total delay is only 0.5 ns, which can achieve a 300 MHz broadband response effect.

[0031] In practice, the number and value of resistors and capacitors can be adjusted according to the magnitude of the input voltage, the frequency range of the output voltage, and the reliability and accuracy of the components.

[0032] Implementation Plan 2

[0033] Reference Figure 4 As shown in the figure, this implementation scheme is the same as implementation scheme 1. The two sets of resistors and capacitors in series in the resistor-capacitor network voltage divider circuit adopt a symmetrical structure. The difference is that the symmetrical structure is not on the upper and lower sides of the same printed circuit board, but is symmetrically installed on the same side plane of the same printed circuit board.

[0034] Implementation Plan 3

[0035] Reference Figure 5As shown in the figure, the two sets of resistors and capacitors in series in the resistor-capacitor network voltage divider circuit of this embodiment are installed in an asymmetrical structure. That is, only one of the two poles between the input port 3 and the output port 4 is provided with a set of resistors and capacitors in series, and the other poles of the two ports are directly connected. Simplifying the embodiment 1 or embodiment 2 will reduce the common mode rejection ratio of the sensor.

Claims

1. A resistor-capacitor network voltage sensing probe, characterized in that... The voltage sensing probe includes an insulating material shell, an input port on the insulating material shell for receiving the signal to be measured, a resistor-capacitor network voltage divider circuit inside the insulating material shell for attenuating high-amplitude DC or low-frequency AC voltage components in the signal to be measured, and an output port on the insulating material shell for connecting to a spectrum analysis device; the resistor-capacitor network voltage divider circuit consists of a resistor and a capacitor connected in series in the loop between the input port and the output port for voltage bearing and voltage division.

2. The voltage sensing probe of a resistor-capacitor network according to claim 1, characterized in that: The resistor-capacitor network voltage divider circuit includes two sets of resistors and capacitors connected in series, which are respectively connected to the two poles between the input port and the output port.

3. The voltage sensing probe of a resistor-capacitor network according to claim 2, characterized in that: The two sets of resistors and capacitors in series are symmetrically installed on the same side or both sides of the same insulating board.

4. The voltage sensing probe of a resistor-capacitor network according to claim 1, characterized in that: The input port and output port are respectively located at opposite ends of the insulating material shell.

5. A voltage sensing probe using a resistor-capacitor network according to claim 1, characterized in that: The input port is a parallel cable interface or a coaxial cable interface.

6. The voltage sensing probe of a resistor-capacitor network according to claim 1, characterized in that: The output port is a two-core parallel cable interface, an SMA or N-type coaxial connector, or a coaxial cable structure.

7. A voltage sensing probe using a resistor-capacitor network according to claim 3, characterized in that: The insulating substrate is a printed circuit board, a ceramic substrate, or a flexible material substrate.

8. The voltage sensing probe of a resistor-capacitor network according to claim 1, characterized in that: The capacitance value of the capacitor in the resistor-capacitor network voltage divider circuit is less than 5 pF.

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