Capacitance and inductance measuring device and measuring equipment

Abstract

The utility model discloses a capacitance and inductance measuring device and measuring equipment, and the device comprises a DDS output module which is used for generating a sine wave signal; the LCR digital bridge module is used for receiving the sine wave signal, converting a response signal of a to-be-detected element into a voltage signal and respectively outputting the voltage signal to the zero-crossing comparator module and the peak detection module; the zero-crossing comparator module is used for converting the voltage signal into a digital square wave signal, capturing a zero-crossing point of the signal and extracting a phase; the peak detection module is used for detecting the amplitude of the voltage signal; and the processor module is used for calculating the loss tangent or the quality factor of the element to be measured according to the phase and the amplitude. The inductance, the quality factor, the capacitance and the loss angle tangent of the inductance can be measured within the range of 1 kHz to 100 kHz, the overall structure is simple, the stability is good, the measurement time is short, and the measurement efficiency of the loss angle tangent value and the quality factor value is effectively improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the capacitance and inductance measurement technical field, especially relate to a kind of capacitance inductance measuring device and measuring equipment. BACKGROUND

[0002] Capacitance and inductance are basic passive components in electronic circuits, widely used in filtering, oscillation, coupling, energy storage and other scenarios. Traditional inductance and capacitance measuring instruments, such as LCR meters, can usually only measure the basic parameters of components, such as capacitance and inductance. However, in practical applications, the loss tangent (D value) and quality factor (Q value) of components are also important indicators of their performance. However, the measuring equipment in the prior art often has limited measurement range, insufficient measurement accuracy or long measurement time when measuring these parameters.

[0003] In addition, the measuring equipment in the prior art mostly uses a single measurement method, such as voltage scaling method and bridge method. These methods may be disturbed by noise when measuring high-frequency signals, resulting in a decrease in the accuracy and stability of the measurement results. At the same time, the hardware structure of traditional measuring equipment is relatively complex and has limited expandability, making it difficult to meet the high requirements of modern electronic devices for measurement accuracy and efficiency. SUMMARY

[0004] The utility model aims at the problems existing in the prior art and provides a capacitance inductance measuring device and measuring equipment that can quickly and accurately detect the loss tangent and quality factor of components.

[0005] On the one hand, the utility model provides a capacitance inductance measuring device, which includes a DDS output module for generating a sine wave signal, an LCR digital bridge module for converting the response signal of the component to be measured into a voltage signal after receiving the sine wave signal and outputting it to a zero-crossing comparator module and a peak detection module, a zero-crossing comparator module for converting the voltage signal into a digital square wave signal, capturing the zero-crossing point of the signal and extracting the phase, a peak detection module for detecting the amplitude of the voltage signal, and a processor module for calculating the loss tangent or quality factor of the component to be measured according to the phase and amplitude.

[0006] The technical scheme has the following beneficial effects: when in use, the to-be-measured element is loaded into the LCR digital bridge module, a sinusoidal signal is output from the DDS output module to the LCR digital bridge module, the response signal of the to-be-measured element is converted into a voltage signal by the LCR digital bridge module and is output to the zero-crossing comparator module and the peak detection module respectively, the phase and the amplitude of the signal are extracted by the zero-crossing comparator module and the peak detection module respectively and are input into the processor module, and the loss tangent value and the quality factor value of the to-be-measured element are calculated by the processor module according to the pre-built calculation program. The application can quickly measure the inductance, the quality factor Q, the capacitance and the loss tangent D in the range of 1 kHz-100 kHz, has a simple overall structure, good stability, short measurement time and effectively improves the measurement efficiency of the loss tangent value and the quality factor value.

[0007] As a further technical scheme, the processor module is further connected with a screen display module for displaying the capacitance and inductance measurement results.

[0008] As a further technical scheme, the LCR digital bridge module comprises a first busbar and a second busbar, the first busbar and the second busbar are connected through the to-be-measured element, the input end of the first busbar is further connected with the output end of the DDS output module, the output end of the second busbar is further connected with the first operational amplifier group, and the output end of the first operational amplifier group is connected with the input end of the peak detection module.

[0009] As a further technical scheme, the zero-crossing comparator module comprises a first comparator and a second comparator; the input end of the first comparator is connected with the output end of the DDS output module, and the input end of the first comparator and the output end of the second comparator are both connected with the processor module.

[0010] As a further technical scheme, the peak detection module comprises two second operational amplifier groups which are identical in structure, one of the second operational amplifier groups receives the output signal of the DDS output module, the other of the second operational amplifier groups receives the output signal of the LCR digital bridge module, and the output ends of the two second operational amplifier groups are both connected with the processor module.

[0011] As a further technical scheme, the peak detection module further comprises an RC filter network.

[0012] As a further technical scheme, the measurement frequency range of the device is 1 kHz to 100 kHz, and the measurement time is not more than 1 second.

[0013] In one aspect, the utility model provides a kind of measurement equipment, be equipped with the capacitance and inductance measuring device of described.

[0014] Compared with the prior art, the utility model has the following beneficial effects:

[0015] The utility model discloses a measured element is installed into the LCR digital bridge module, and the DDS output module exports the sinusoidal wave signal to the LCR digital bridge module, and the response signal of the measured element is converted into the voltage signal through the LCR digital bridge module and is exported to the zero crossing comparator module and the peak detection module respectively, and the phase and amplitude of the signal are extracted through the zero crossing comparator module and the peak detection module and are input to the processor module, and the loss tangent value and the quality factor value of the measured element are calculated through the processor module according to the prebuilt calculation program. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is the system circuit composition block diagram provided by the utility model embodiment;

[0017] Figure 2 It is the LCR digital bridge module circuit diagram provided by the utility model embodiment;

[0018] Figure 3 It is the zero crossing comparator module circuit diagram provided by the utility model embodiment;

[0019] Figure 4 It is the peak detection module circuit diagram provided by the utility model embodiment;

[0020] Figure 5 It is the DDS output module circuit diagram provided by the utility model embodiment;

[0021] Figure 6 It is the circuit diagram of the processor module provided by the utility model embodiment;

[0022] Figure 7 It is the OLED display module circuit diagram provided by the utility model embodiment. DETAILED DESCRIPTION

[0023] The technical scheme of the utility model will be described clearly and completely below in combination with the drawings in the utility model, and obviously, the described embodiments are only part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the scope of protection of the utility model.

[0024] As Figure 1As shown, the utility model embodiment provides a kind of capacitance inductance measuring device, comprising: DDS output module, for generating sine wave signal;LCR digital bridge module, for receiving after the sine wave signal, the response signal of the element to be measured is converted into voltage signal and is respectively output to zero-crossing comparator module and peak detector module;Zero-crossing comparator module, for converting the voltage signal into digital square wave signal, capture the zero-crossing point of signal and extract phase;Peak detector module, for detecting the amplitude of the voltage signal;Processor module, for calculating the loss tangent or quality factor of the element to be measured according to the phase and amplitude, and the processor module is also connected with screen display module, for displaying capacitance inductance measurement result.

[0025] The utility model embodiment can effectively determine inductance, quality factor Q, capacitance and loss tangent D, and has simple overall structure, good stability, short measurement time, effectively improves the measurement efficiency of loss tangent value and quality factor value.

[0026] In the embodiment, the LCR digital bridge module is used to convert the response signal of the element to be measured into voltage signal, i.e. two DC-biased sine waves, after DDS input sine wave, to provide signal amplitude and phase difference information;The zero-crossing comparator module is used to convert the two DC-biased sine waves output by the LCR digital bridge module into two digital square wave signals, capture the zero-crossing point of signal, and extract phase information;The peak detector module is used to detect the amplitude of the DC-biased sine wave, and obtain the amplitude of the two sine waves;The DDS output module is used to generate high-precision sine wave signal, and provide controllable frequency signal as the input of the LCR digital bridge module;The processor module is used to control the operation of each hardware module, including frequency setting, data sampling and processing of DDS signal, calculate capacitance value, inductance value, loss tangent and quality factor through program algorithm, and transmit the processing result to the screen display module;The screen display module is used to display the measurement result in real time, including inductance and quality factor, capacitance and loss tangent.

[0027] As Figure 2 shown, in the embodiment, the LCR digital bridge module includes first row of mother A2 and second row of mother A1, and the first row of mother A2 and the second row of mother A1 are connected through the element to be measured;When detecting the element to be measured, the input end of the element to be measured is inserted into the first row of mother A2, and the output end is inserted into the second row of mother U1.

[0028] The input end of the first row of female A2 is connected with the output end of the DDS output module to receive the sine wave emitted by the DDS output module. The capacitor C3 and the resistor R15 are connected in series between the output end of the DDS output module and the input end of the first row of female A2. After the sine wave output by the DDS output module passes through the capacitor C3 and the resistor R15, the sine wave is transmitted to the first row of female A2 and is also transmitted to the peak detection module in the form of a voltage signal.

[0029] Secondly, the output end of the second row of female is connected with the first operational amplifier group. The first operational amplifier group converts the response signal of the to-be-tested element into a voltage signal, i.e., two direct-current bias-free sine waves, to provide signal amplitude and phase difference information. The output end of the first operational amplifier group is connected with the input end of the peak detection module.

[0030] As shown in Figure 2 The first operational amplifier group includes the first operational amplifier B1, the second operational amplifier B2, the third operational amplifier B3 and the fourth operational amplifier B4. The positive input end of the first operational amplifier B1 is connected with the output end of the second row of female A1. The negative input end of the first operational amplifier B1 is connected with the positive input end of the fourth operational amplifier B4. The output end of the first operational amplifier B1 is connected between the negative input end of the first operational amplifier B1 and the positive input end of the fourth operational amplifier B4. The positive input end of the second operational amplifier B2 is grounded. The negative input end of the second operational amplifier B2 is connected with the output end of the second row of female A1. The output end of the second operational amplifier B2 is connected with the positive input end of the third operational amplifier. The output end of the third operational amplifier B3 is connected with the negative input end of the fourth operational amplifier B4. The output end of the third operational amplifier B3 and the negative input end of the fourth operational amplifier B4 are both connected with the input end of the peak detection module. The negative input end of the third operational amplifier B3 is connected between the output end of the third operational amplifier B3 and the negative input end of the fourth operational amplifier B4. The output end of the fourth operational amplifier B4 is connected with the input end of the peak detection module.

[0031] It should be noted that the above operational amplifiers all adopt high-precision low-noise operational amplifier OPA2227.

[0032] As shown in Figure 3 The over-zero comparator module includes the first comparator Δ1 and the second comparator Δ2. The input end of the first comparator Δ1 is connected with the output end of the DDS output module. The input end of the first comparator Δ1 and the output end of the second comparator Δ2 are both connected with the processor module ◇1.

[0033] In this embodiment, the first comparator Δ1 and the second comparator Δ2 both use high-speed comparators TLV3501 to convert the two DC-biased-free sinusoidal waves V_OUT and I_OUT output by the LCR digital bridge module into two digital square wave signals H1 and H2, so as to ensure fast response and accurately capture the zero-crossing point of the signal and extract the phase information. An external pull-up resistor network is used at the +IN pin to ensure fast response and stability of the signal. The high-speed working performance of this module ensures that the system can accurately process high-frequency signals such as 100 kHz and provide accurate digitized input for subsequent phase difference calculation.

[0034] As shown in Figure 4 The peak detection module includes two second operational amplifier groups, and the two second operational amplifier groups are identical in structure. One of the second operational amplifier groups receives the output signal of the DDS output module, and the other second operational amplifier group receives the output signal of the LCR digital bridge module. The output ends of the two second operational amplifier groups are connected with the processor module.

[0035] In this embodiment, the second operational amplifier group includes operational amplifier one, operational amplifier two, and operational amplifier three. The positive input end of the operational amplifier one is connected with the DDS output module or the LCR digital bridge module. The output end of the operational amplifier one is connected with the positive input end of the operational amplifier two. The negative input end of the operational amplifier one is connected between the output end of the operational amplifier one and the positive input end of the operational amplifier two. The negative input end of the operational amplifier two is connected with the processor module. The output end of the operational amplifier two is connected with the positive input end of the operational amplifier three. The negative input end of the operational amplifier three is connected between the negative input end of the operational amplifier two and the processor module. The operational amplifier three is connected with the processor module.

[0036] The operational amplifiers involved in the peak detection module all use high-precision low-noise operational amplifiers OPA2227. The high-precision performance of OPA2227 can improve the calculation accuracy. The peak detection module is used to detect the amplitude of DC-biased-free sinusoidal waves and has high dynamic response capability, which can quickly capture high-frequency signals such as 100 kHz and output stable peak voltage data, thereby providing necessary amplitude information for calculating the characteristic parameters of the measured element.

[0037] At the same time, in order to ensure the detection accuracy, an RC filter network composed of a capacitor C1 and a resistor R1 and a capacitor C2 and a resistor R2 is designed in the detection circuit after the signal input, which is used to smooth the waveform and reduce the measurement noise interference.

[0038] As shown in Figure 5As shown, the DDS output module U1 in this example is implemented using a chip model AD9834BRUZ, the 17th pin of the DDS output module U1 is connected to the first busbar A2 for sending a sine wave signal, and the 16th pin of the DDS output module U1 is connected to the processor module for receiving the instructions sent by the processor module.

[0039] In use, the DDS output module U1 controls the generation of a high-precision sine wave signal, and the output frequency range can be set between 1 kHz and 100 kHz, and the DDS output module U1 provides a controllable frequency signal as the input of the LCR digital bridge module. The output end of the DDS output module U1 is directly connected to the input end of the LCR digital bridge module to provide an accurate excitation signal for measurement.

[0040] As shown in Figure 6 The processor module is implemented using a high-speed FPGA of the Cyclone IV series of Altera Company with a model EP4CE40F23C8N, the FPGA is connected to other modules through its multifunctional I / O interface, is used for controlling the signal generation of the DDS output module, the signals output by the zero-crossing comparator module and the peak detection module, and performing digital processing on the signals. The input end of the FPGA is connected to the output end of the zero-crossing comparator module and the peak detection module to receive two groups of digital square wave signals and two groups of peak signals; the output end controls the DDS module through an SPI interface and connects an OLED display module through an I2C interface to output the measurement results. The FPGA internally runs a control program written in Verilog language, calculates the capacitance, inductance, quality factor (Q value) and loss tangent (D value) of the to-be-measured element through a high-speed digital signal processing algorithm. This module supports multi-task parallel processing, ensures that all calculation tasks are completed in a short time, and its high expansibility provides a possibility for subsequent functional upgrade. It should be noted that the digital signal processing algorithm of the capacitance, inductance, quality factor and loss tangent of the to-be-measured element is implemented using a mature algorithm in the field, and the specific program writing in Verilog language also belongs to a conventional means in the field, and the utility model does not make redundant description here.

[0041] Specifically, the AA1 pin of the processor module is connected to the DDS output module U1, the AA11 pin and the AA13 pin of the processor module receive the signals sent by the two output ends of the second operational amplifier group respectively, the AA15 pin and the AA17 pin of the processor module receive the output signals of the first comparator and the second comparator respectively, and the AA19 pin and the AA11 pin of the processor module are both connected to the screen display module.

[0042] As shown in Figure 7As shown, the model of the screen display module OLED1 is HS13L03W2C01, the driving chip is SH1106, the 132*64 dot matrix OLED display panel is adopted, the 132*64 bit SRAM display buffer is integrated inside, the pin 1 of the screen display module OLED1 is grounded, the pin 2 is connected with the power supply of 3.3V, the pin 3 and the pin 4 are connected with the AA19 pin and the AA11 pin of the processor module 1 respectively. The screen display module OLED1 has low power consumption and high brightness display performance. The module supports high refresh rate display, ensures that the measurement result can be accurately presented to the user in a short time, and provides a friendly interactive experience for the user.

[0043] Finally, the measurement frequency range of the present application is 1kHz to 100kHz, and the measurement time is not more than 1 second, and the programs involved in the embodiments of the present application are prior art, so they will not be repeated here.

[0044] Based on the same technical concept as the above-mentioned embodiments, the utility model embodiment further provides a measuring device, which is configured with the capacitance and inductance measuring device involved in the above-mentioned embodiments.

[0045] The working principle of the above-mentioned embodiments is as follows:

[0046] The processor module sends instructions to the DDS output module through its control pin, controls the DDS module to generate a high-precision sinusoidal signal, and the frequency range is set between 1kHz to 100kHz. The sinusoidal signal is used as an excitation signal and is input to the LCR digital bridge module through the first row of mothers A2.

[0047] The LCR digital bridge module receives the sinusoidal signal of the DDS module and applies it to the measured element. The response signal of the measured element, that is, two DC-free sinusoidal waves, is processed by the first operational amplifier group, converted into a voltage signal, and provides amplitude and phase difference information of the signal.

[0048] The zero-crossing comparator module receives the sinusoidal signal output by the LCR digital bridge module, converts it into a digital square wave signal, captures the zero-crossing point of the signal, extracts the phase information, and transmits these digital square wave signals to the processor module.

[0049] The peak detection module receives the sinusoidal wave signal output by the LCR digital bridge module, detects the peak amplitude of the signal through the second operational amplifier group, and transmits the peak signals to the processor module. The processor module receives the digital square wave signal from the zero-crossing comparator module and the peak signal from the peak detection module. Through the built-in program, the processor module calculates the capacitance value, inductance value, loss tangent (D value) and quality factor (Q value) of the measured element. After the calculation is completed, the processor module sends the measurement results to the screen display module (OLED display screen) through its output pins (such as AA19 and AA11 pins). The screen display module receives the measurement results of the processor module and displays them in digital form on the OLED screen in real time, providing an intuitive display of the measurement results for the user.

[0050] Although the embodiments of the present application have been shown and described, it should be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A capacitance and inductance measuring device, characterized in that, include: The DDS output module is used to generate a sine wave signal; the LCR digital bridge module is used to receive the sine wave signal, convert the response signal of the device under test into a voltage signal, and output it to the zero-crossing comparator module and the peak detection module respectively. The zero-crossing comparator module is used to convert the voltage signal into a digital square wave signal, capture the zero-crossing point of the signal and extract the phase; the peak detection module is used to detect the amplitude of the voltage signal. The processor module is used to calculate the loss tangent or quality factor of the component under test based on the phase and amplitude.

2. The capacitance and inductance measuring device according to claim 1, characterized in that, The processor module is also connected to a screen display module for displaying capacitance and inductance measurement results.

3. The capacitance and inductance measuring device according to claim 1, characterized in that, The LCR digital bridge module includes a first busbar and a second busbar, which are connected by a device under test. The input terminal of the first busbar is also connected to the output terminal of the DDS output module, and the output terminal of the second busbar is also connected to a first operational amplifier group. The output terminal of the first operational amplifier group is connected to the input terminal of the peak detector module.

4. The capacitance and inductance measuring device according to claim 1, characterized in that, The zero-crossing comparator module includes a first comparator and a second comparator; the input of the first comparator is connected to the output of the DDS output module, and the input of the first comparator and the output of the second comparator are both connected to the processor module.

5. The capacitance and inductance measuring device according to claim 1, characterized in that, The peak detection module includes two second operational amplifier groups with identical structures. One second operational amplifier group receives the output signal from the DDS output module, and the other second operational amplifier group receives the output signal from the LCR digital bridge module. The output terminals of both second operational amplifier groups are connected to the processor module.

6. The capacitance and inductance measuring device according to claim 5, characterized in that, The peak detection module also includes an RC filter network.

7. The capacitance and inductance measuring device according to claim 1, characterized in that, The measurement frequency range of the device is from 1 kHz to 100 kHz, and the measurement time does not exceed 1 second.

8. A measuring device, characterized in that, It is equipped with the capacitance and inductance measuring device as described in any one of claims 1-7.

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