A gateway metering analog-to-digital converter test device

Abstract

The utility model discloses a kind of gateway metering modulus converter testing device, it is related to electric power measurement technical field, solve the problem that traditional test scheme cannot accurately adapt to power system's power frequency signal, and test stability, low universality.The signal source module can directional output preset frequency band's sinusoidal signal or direct current signal, calibration module is connected by reference voltage source, automatic calibration switch and signal source module, can carry out precision calibration to the output power frequency sinusoidal signal or direct current signal in real time;Core module is integrated in modularization machine case, and is connected uniformly by backplane bus, reduce external interference source access, simultaneously avoid the signal attenuation caused by cable transmission;Isolation module can carry out isolation anti-interference processing to test signal;Analog-digital conversion module is with the interface structure of adaptation ADC to be tested, can realize the access of different packaging ADC, realize the improvement on device test precision, stability, universality, operation convenience.

Description

Technical Field

[0001] This utility model relates to the field of power metering technology, and in particular to a metering analog-to-digital converter testing device. Background Technology

[0002] In power systems, gateway meters are core devices used to measure the exchange of electrical energy between the generation and consumption sides, and between different power grid areas. The analog-to-digital converter (ADC), as the core data acquisition unit of the gateway meter, directly determines its overall metering accuracy. Currently, the testing method for the ADC of gateway meters typically involves a combination of multiple independent instruments connected to a host computer to perform dynamic and static performance tests.

[0003] Power systems have stringent requirements for the metering accuracy of gateway meters. As a core component, the performance of analog-to-digital converters (ADCs) under power frequency signals directly determines the accuracy of gateway meters. However, traditional solutions have two major bottlenecks: First, there is a lack of specific optimization for power frequency signals. Power system electrical signals are characterized by power frequency signals (50Hz or 60Hz), while most mainstream ADC chips on the market are designed for high-frequency signals of 1000Hz and above by default. However, they lack spectrum optimization design for power frequency signals, resulting in high signal harmonic distortion and large temperature drift, making it impossible to accurately test the power frequency performance of ADCs. Second, the connection of multiple independent instruments and the resulting dispersed layout lead to interference, poor adaptability, and timing deviations, further reducing the reliability of the test.

[0004] It is evident that traditional testing methods cannot accurately adapt to the power frequency signals of the power system, and the stability and versatility of the tests are insufficient to meet the metering accuracy requirements of the gate meter. These are technical problems that urgently need to be solved by those in the field. Utility Model Content

[0005] The purpose of this invention is to provide a metering analog-to-digital converter testing device for gate meters, which solves the problems that traditional testing schemes cannot accurately adapt to the power frequency signals of the power system, and that the testing stability and versatility are difficult to meet the metering accuracy requirements of gate meters.

[0006] To solve the above-mentioned technical problems, this utility model provides a metering analog-to-digital converter testing device, comprising: a signal source module for outputting a sinusoidal signal or DC signal of a preset frequency band, an analog-to-digital converter module, an isolation module, a calibration module, a transmission module, and a modular chassis;

[0007] The modular chassis is equipped with a backplane bus, and the signal source module, the analog-to-digital converter module, the isolation module, the calibration module and the transmission module are all connected to the backplane bus;

[0008] The output of the signal source module is connected to the input of the isolation module via a signal switching switch; the analog-to-digital converter module is detachably connected to the modular chassis, and the signal input of the analog-to-digital converter module is connected to the output of the isolation module.

[0009] The analog-to-digital converter module is equipped with an interface structure adapted to the analog-to-digital converter under test. The analog-to-digital converter under test is connected to the analog-to-digital converter module through the interface structure to receive the test signal transmitted through the isolation module; and the output terminal of the analog-to-digital converter under test is connected to the transmission module.

[0010] The calibration module includes a reference voltage source and an automatic calibration switch, wherein the reference voltage source is connected to the signal source module through the automatic calibration switch;

[0011] The transmission module is connected to an external host computer via an isolated bus.

[0012] As an optional solution, in the above-mentioned metering analog-to-digital converter testing device, the isolation module includes an electromagnetic shielding cavity and an isolation device;

[0013] The electromagnetic shielding cavity is installed outside the signal output channel of the signal source module and the signal input channel of the analog-to-digital converter module.

[0014] The isolation device is connected in series between the signal source module and the analog-to-digital converter module.

[0015] As an optional solution, in the above-mentioned metering analog-to-digital converter testing device, the isolation device includes a differential isolation transformer and an optocoupler connected in parallel;

[0016] The input terminal of the differential isolation transformer is connected to the output terminal of the signal source module, and the output terminal is connected to the input terminal of the isolation module, for transmitting high-bandwidth test signals;

[0017] The input terminal of the optocoupler is connected to the output terminal of the signal source module, and the output terminal is connected to the input terminal of the isolation module, for transmitting low-speed control signals;

[0018] A phase matching circuit is provided between the differential isolation transformer and the optocoupler, and the phase matching circuit is used to keep the signal transmission delay of the two consistent.

[0019] As an optional solution, in the above-mentioned metering analog-to-digital converter testing device, the interface structure of the analog-to-digital conversion module is a multi-layer stacked adapter socket;

[0020] The multi-layer stacked adapter socket includes at least two layers of socket units for adapting analog-to-digital converters of different package types to be tested, and each of the socket units is stacked along the height direction of the analog-to-digital converter module;

[0021] Each of the socket units is connected to the internal signal channel of the analog-to-digital converter module through an adjustable pin mapping component. The adjustable pin mapping component is used to enable the corresponding conduction of the pins of the analog-to-digital converters under test with the internal signal channel for different packages.

[0022] As an optional solution, in the above-mentioned metering analog-to-digital converter testing device, the adjustable pin mapping component is a miniature DIP switch;

[0023] The input terminal of the miniature DIP switch is connected to the pin of the multi-layer stacked adapter socket, and the output terminal is connected to the internal signal channel of the analog-to-digital converter module. By adjusting the position of the miniature DIP switch, the connection between different socket units in the multi-layer stacked adapter socket and the internal signal channel can be switched to adapt to the corresponding packaged analog-to-digital converter under test.

[0024] As an optional solution, in the above-mentioned metering analog-to-digital converter testing device, the signal switching switch is a dual-redundant solid-state switch array;

[0025] The input terminal of the dual redundant solid-state switch array is connected to the output terminal of the signal source module, and the output terminal is connected to the input terminal of the isolation module.

[0026] An RC soft-start network is provided between the input terminal of the dual redundant solid-state switch array and the signal source module, and between the output terminal of the dual redundant solid-state switch array and the isolation module. The RC soft-start network is used to reduce the voltage surge during signal switching.

[0027] As an optional solution, in the above-mentioned metering analog-to-digital converter test device, the backplane bus is a three-layer symmetrical printed circuit board structure, including signal layers on both sides and a power layer in the middle.

[0028] The signal layer is connected to the signal pins of the signal source module, analog-to-digital converter module, isolation module, calibration module, and transmission module, and is used to transmit test signals and control commands.

[0029] The power layer is connected to the power pins of each module and is used to supply power to each module.

[0030] As an optional solution, in the above-mentioned metering analog-to-digital converter testing device, the transmission module includes a microcontroller control channel, a high-speed data channel, and a synchronous triggering logic circuit;

[0031] One end of the microcontroller control channel is connected to the backplane bus, and the other end is connected to an external host computer through the isolation bus, for transmitting control commands issued by the host computer.

[0032] One end of the high-speed data channel is connected to the output of the analog-to-digital converter under test, and the other end is connected to an external host computer through the isolation bus to transmit the conversion data output by the analog-to-digital converter under test.

[0033] The synchronous triggering logic circuit is connected to the microcontroller control channel and the high-speed data channel respectively, and is used to synchronously control the transmission timing of the control commands and the converted data to keep them aligned.

[0034] As an optional solution, in the above-mentioned metering analog-to-digital converter testing device, the input terminal of the automatic calibration switch is connected to the output terminal of the reference voltage source, and the output terminal is connected to the signal generation unit of the signal source module; by switching the on / off state of the automatic calibration switch, the standard voltage signal of the reference voltage source can be selectively connected to the signal source module to calibrate the sinusoidal signal or DC signal output by the signal source module.

[0035] As an optional solution, in the above-mentioned metering analog-to-digital converter testing device, the signal source module includes a sine wave signal source unit, which is composed of a direct digital frequency synthesis chip, a multi-segment programmable filter and a digital predistortion compensation subunit connected in sequence.

[0036] The output of the direct digital frequency synthesis chip is connected to the input of the multi-segment programmable filter to generate a basic sine signal.

[0037] The output of the multi-segment programmable filter is connected to the input of the digital predistortion compensation subunit, and is used to filter the basic sine signal.

[0038] The output of the digital predistortion compensation subunit is connected to the input of the signal switching switch, and is used to load the spectrum correction coefficient to correct the harmonic components of the signal so that the output sinusoidal signal conforms to the characteristics of the power system frequency signal.

[0039] The metering analog-to-digital converter (ADC) testing device provided by this utility model has a signal source module that can output sinusoidal or DC signals in a preset frequency band. The sinusoidal signal can be specifically matched to the power frequency (50Hz / 60Hz), eliminating the need for high-frequency signal adaptation capabilities of general-purpose instruments. The calibration module is connected to the signal source module via a reference voltage source and an automatic calibration switch, enabling real-time precision calibration of the output power frequency sinusoidal or DC signal. This calibration compensates for deviations such as temperature drift and harmonic distortion, ensuring that the test signal is consistent with the actual power frequency signal characteristics of the power system, making the ADC test results more closely resemble real-world operating conditions. The core modules (signal source, analog-to-digital converter, isolation, calibration, and transmission) are all integrated within a modular chassis and uniformly connected via a backplane bus, replacing the traditional multi-instrument distributed wiring mode, reducing the access of external interference sources, and avoiding signal attenuation caused by cable transmission. The isolation module is connected in series in the core signal path from the output of the signal source module to the input of the analog-to-digital converter module, which can isolate and resist interference of the test signal, solving the problem of signal susceptibility to interference in traditional solutions. The analog-to-digital converter module has a built-in interface structure to adapt to the ADC under test, eliminating the need for additional independent adapter instruments and enabling the access of ADCs with different packages. This application solves the problems of power frequency adaptation deviation, poor interference and stability, low adaptability, and timing misalignment through the core design of directional output and calibration of power frequency signals, modular integrated isolation, universal adapter interface, and unified transmission link, achieving improvements in test accuracy, stability, versatility, and ease of operation. Attached Figure Description

[0040] To more clearly illustrate the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This utility model provides a schematic diagram of a metering analog-to-digital converter testing device.

[0042] The reference numerals in the attached diagram are as follows: 101-Signal source module; 102-Analog-to-digital converter module; 103-Isolation module; 104-Calibration module; 105-Transmission module; 106-Modular chassis. Detailed Implementation

[0043] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0044] The existing metering analog-to-digital converter testing method mainly involves a host computer controlling a sine wave generator, a high-precision DC source, and a high-precision tester via a universal serial bus (USB).

[0045] Sine wave signal testing involves generating a sinusoidal signal with a specified frequency, amplitude, and phase using a sinusoidal signal generator, outputting it to the analog-to-digital converter (ADC) under test, and then obtaining the analog-to-digital conversion result of the ADC through a microcontroller unit (MCU). This result is then transmitted to a host computer via Ethernet. The host computer obtains the signal spectrum through adaptive frequency estimation and Fourier analysis, and then performs tests on the signal-to-noise ratio (SNR), total harmonic distortion (THD), signal-to-noise ratio (SINAD), crosstalk, and noise based on the signal spectrum.

[0046] DC signal testing involves emitting a highly stable DC signal from a DC source. The DC signal is simultaneously output to the tester and the ADC. The tester obtains the actual voltage value, and the MCU main control obtains the code value. Then, the host computer constructs an integral nonlinear INL curve based on the actual voltage value and the code value to obtain the DC signal test result.

[0047] However, existing testing devices rely on multiple independent instruments, have complex wiring and are susceptible to signal interference, and have poor interface compatibility, resulting in unstable testing processes and insufficient versatility, making it difficult to meet the requirements for accurate performance evaluation under power frequency signals in power systems.

[0048] The core of this utility model is to provide a metering analog-to-digital converter testing device.

[0049] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] This application provides a metering analog-to-digital converter testing device, including: a signal source module 101 for outputting a sinusoidal signal or DC signal of a preset frequency band, an analog-to-digital conversion module 102, an isolation module 103, a calibration module 104, a transmission module 105, and a modular chassis 106.

[0051] The modular chassis 106 has a backplane bus, and the signal source module 101, analog-to-digital converter module 102, isolation module 103, calibration module 104 and transmission module 105 are all connected to the backplane bus.

[0052] The output of the signal source module 101 is connected to the input of the isolation module 103 via a signal switching switch; the analog-to-digital converter module 102 is detachably connected to the modular chassis 106, and the signal input of the analog-to-digital converter module 102 is connected to the output of the isolation module 103.

[0053] The analog-to-digital converter module 102 is equipped with an interface structure adapted to the analog-to-digital converter under test. The analog-to-digital converter under test is connected to the analog-to-digital converter module 102 through the interface structure to receive the test signal transmitted through the isolation module 103; and the output terminal of the analog-to-digital converter under test is connected to the transmission module 105.

[0054] The calibration module 104 includes a reference voltage source and an automatic calibration switch. The reference voltage source is connected to the signal source module 101 through the automatic calibration switch.

[0055] The transmission module 105 is connected to an external host computer via an isolation bus.

[0056] First, the signal source module 101 is used to output a sinusoidal signal or a DC signal in a preset frequency band. In power system scenarios, the preset frequency band is generally the main power frequency signal (50Hz or 60Hz). The output sinusoidal signal is used to test the dynamic performance (such as harmonic distortion and signal-to-noise ratio) of the analog-to-digital converter under test, while the output DC signal is used to evaluate its static performance (such as nonlinear error).

[0057] It should be noted that the preset frequency band does not mean it can only cover the power frequency. It can be extended to other frequency bands (such as 45Hz-65Hz) according to testing needs to verify the adaptability of the analog-to-digital converter, but the core is still aimed at the characteristic frequency band of the power system. Possible implementation methods include: using direct digital frequency synthesis technology to generate a sine wave signal, and using a high-precision reference source superimposed with a temperature compensation circuit to generate a DC signal to ensure the stability and accuracy of the output signal.

[0058] Specifically, the signal source module 101 includes a sinusoidal signal source unit and a DC signal source unit, which are connected to the signal output terminal through a signal switching switch. The DC signal source unit includes a dual reference source superposition structure, wherein the dual reference sources are a high-stability temperature-compensated reference source and a low-drift charge pump reference source, and a miniature thermal coupling compensation network is used to dynamically correct for changes in ambient temperature.

[0059] For example, the DC signal source unit can adopt a dual-reference superposition structure: the high-stability reference source is selected from LTZ1000A (drift <0.05ppm / ℃), and the low-drift charge pump reference source adopts a self-excited oscillation circuit; the two are superimposed by an operational amplifier and output. The miniature thermal coupler compensation network includes a thermistor array and a proportional-integral control circuit to control the temperature drift of the output voltage within ±1ppm.

[0060] The analog-to-digital converter module 102 is used to physically connect the analog-to-digital converter under test (ADC) to the device and transmit signals. It is detachably connected to the modular chassis 106. When it is necessary to test ADCs with different package types, the test can be completed by replacing the appropriate ADC module 102 without modifying other parts of the device, thus improving the device's versatility.

[0061] The interface structure for the analog-to-digital converter under test (ADC) is a connection component that matches the pin layout and package form of the ADC under test. Possible implementation methods include: multi-layer stacked socket structure, each adapting to ADCs with different packages; replaceable interface panels, adapting to specific types of ADCs by changing different interface components; or using a general-purpose test probe array, with pin mapping implemented through software configuration.

[0062] The isolation module 103 is located between the signal source module 101 and the analog-to-digital converter module 102. Its purpose is to block interference in the signal transmission path, including electromagnetic interference and common-mode noise. In power system testing environments, there are many sources of interference. Without isolation, the test signal may be distorted, affecting the performance evaluation results of the analog-to-digital converter under test.

[0063] It should be noted that the specific isolation method of the isolation module 103 is not unique, as long as it can achieve the anti-interference function. It can use electromagnetic isolation (such as an isolation transformer) to transmit signals through magnetic field coupling and achieve electrical isolation; it can also use opto-isolation (such as an optocoupler) to transmit information using optical signals and avoid electrical connection; or it can use magneto-optical isolation (such as fiber optic transmission) to further improve the anti-interference capability. In addition, the isolation module 103 can also be used in conjunction with an electromagnetic shielding structure (such as a metal shielding box) to form a double anti-interference guarantee. This embodiment does not impose strict limitations.

[0064] The calibration module 104 includes a reference voltage source and an automatic calibration switch. The reference voltage source is connected to the signal source module 101 via the automatic calibration switch. Its purpose is to ensure the accuracy of the output signal of the signal source module 101. Since the signal source module 101 may experience output deviations due to factors such as temperature and component aging during long-term operation, it can be calibrated using the standard signal provided by the reference voltage source.

[0065] The automatic calibration switch controls the start and stop of the calibration process. When calibration is required, the switch is turned on, and the reference voltage source is connected to the signal source module 101. After calibration is completed, the switch is turned off, without affecting the normal output of the signal source module 101. The reference voltage source generally uses a high-stability reference chip (such as a low-temperature drift voltage reference) to ensure the accuracy of the calibration.

[0066] The transmission module 105 is connected to an external host computer via an isolation bus. On the one hand, it receives control commands from the host computer (such as setting signal source output parameters, starting the test, etc.). On the other hand, it uploads the conversion data output by the analog-to-digital converter under test to the host computer for analysis and processing.

[0067] The isolated bus has anti-interference capabilities, and possible implementation methods include using isolated Ethernet interfaces, USB interfaces, or fiber optic interfaces. In addition, the transmission module 105 can be equipped with a data buffer unit, such as a FIFO (First Input First Output) memory, for temporary storage of test data to avoid data loss; it can also integrate a synchronous clock circuit to ensure time synchronization with the host computer and improve the time correlation of data.

[0068] The modular chassis 106 provides installation space and physical protection for each module, while enabling signal and power transmission between modules through an internal backplane bus. The backplane bus, acting as the connection hub between modules, performs both signal transmission and power distribution functions, connecting the signal source module 101, analog-to-digital converter module 102, isolation module 103, calibration module 104, and transmission module 105 into a cohesive whole, replacing the complex external wiring of traditional solutions.

[0069] The backplane bus may employ a multi-layer printed circuit board structure to separate power transmission from signal transmission, reducing mutual interference. Modular design makes installation and replacement of modules more convenient, and also facilitates later maintenance and functional expansion.

[0070] In summary, the metering analog-to-digital converter testing device provided by this utility model has a signal source module 101 that can output a sinusoidal signal or DC signal in a preset frequency band. The sinusoidal signal can be specifically matched to the power frequency (50Hz / 60Hz), eliminating the need for high-frequency signal adaptation capabilities of general-purpose instruments. The calibration module 104 is connected to the signal source module 101 via a reference voltage source and an automatic calibration switch, enabling real-time precision calibration of the output power frequency sinusoidal signal or DC signal. This calibration compensates for deviations such as temperature drift and harmonic distortion, ensuring that the test signal is consistent with the actual power frequency signal characteristics of the power system, making the ADC test results more closely resemble real-world operating conditions. All core... The core modules (signal source, analog-to-digital converter, isolation, calibration, and transmission) are all integrated within the modular chassis 106 and uniformly connected via a backplane bus, replacing the traditional multi-instrument distributed wiring mode, reducing the access of external interference sources, and avoiding signal attenuation caused by cable transmission. The isolation module 103 is connected in series in the core signal path from the output of the signal source module 101 to the input of the analog-to-digital converter module 102, which can isolate and resist interference of the test signal, solving the problem of signal susceptibility to interference in traditional solutions. The analog-to-digital converter module 102 has a built-in interface structure to adapt to the ADC under test, and can realize the access of ADCs with different packages without the need for additional independent adapter instruments. This application solves the problems of power frequency adaptation deviation, poor interference and stability, low adaptability, and timing misalignment through the core design of directional output and calibration of power frequency signals, modular integrated isolation, universal adapter interface, and unified transmission link, and improves the test accuracy, stability, universality, and ease of operation.

[0071] According to the above embodiments, in one specific embodiment, the isolation module 103 includes an electromagnetic shielding cavity and an isolation device;

[0072] An electromagnetic shielding cavity is installed outside the signal output channel of the signal source module 101 and the signal input channel of the analog-to-digital converter module 102;

[0073] An isolation device is connected in series between the signal source module 101 and the analog-to-digital converter module 102.

[0074] First, an electromagnetic shielding cavity is installed outside the signal output channel of the signal source module 101 and the signal input channel of the analog-to-digital converter module 102. Its core function is to construct a physical barrier to block external electromagnetic radiation from interfering with sensitive signal paths. The signal output channel and the signal input channel are critical paths for test signal transmission. Analog signals are particularly sensitive to electromagnetic interference, so both are included in the same shielding cavity to form a complete shielding space, preventing interference signals from entering from the output-input junction. The electromagnetic shielding cavity can be implemented in various ways: it can be integrally die-cast using a high-conductivity metal material (such as copper or aluminum alloy), or it can be made of spliced ​​metal sheets with conductive adhesive sealing the gaps. The cavity interior can be equipped with partition structures as needed to separately shield different signal paths (such as sinusoidal signal channels and DC signal channels), further reducing internal crosstalk. Furthermore, the cavity grounding method can be flexibly designed; it can be single-point grounding to reduce ground loops, or it can be connected to the modular chassis 106 via spring contacts to achieve a common ground. This embodiment does not impose strict limitations.

[0075] For example, the electromagnetic shielding cavity can be made of a 1.5mm thick copper plate coated with a silver coating, and the silver-copper composite coating can be achieved through a chemical plating process. The segmented grounding ring is a nickel-plated steel sheet wound into a helical spring shape and installed on the edge of the cavity. The contact surface self-adapts and fits through compression elasticity, and the grounding resistance remains less than 5mΩ after 100 disassembly and reassembly cycles.

[0076] Secondly, an isolation device is connected in series between the signal source module 101 and the analog-to-digital converter module 102. Its function is to achieve electrical isolation, preventing potential differences or common-mode noise between the signal source side and the analog-to-digital converter under test from affecting signal transmission. It should be noted that the electromagnetic shielding cavity mainly solves spatial electromagnetic radiation interference, while the isolation device targets conducted interference in the line, forming a complementary relationship.

[0077] The specific type of isolation device is not unique. For AC signals such as sinusoidal signals, differential isolation transformers can be used to transmit signals through magnetic coupling while blocking DC components. For DC signals or low-speed control signals, optocouplers can be used to achieve isolation through photo-to-electric conversion, suitable for mixed high and low voltage scenarios. In high-precision scenarios, magnetoresistive isolators or capacitive isolators can also be used to obtain lower transmission delays and higher linearity. In addition, the isolation voltage level of the isolation device can be selected according to the test requirements (such as 2.5kV, 5kV or higher), and does not mean that only a certain specific specification can be used.

[0078] It should also be noted that the combined design of the electromagnetic shielding cavity and the isolation device does not mean that the two must be strictly independent. In practical applications, the isolation device can be installed inside the electromagnetic shielding cavity, integrating the isolation and shielding functions in physical space, reducing signal path length, and further improving the anti-interference effect.

[0079] In addition, a miniature temperature control unit is added outside the electromagnetic shielding cavity to maintain a constant internal temperature through a thermoelectric cooler, thereby improving the long-term stability of the test.

[0080] Based on the above analysis, this embodiment uses the coordinated design of an electromagnetic shielding cavity and an isolation device to block spatial radiation interference and suppress line conducted interference, thus jointly ensuring the purity of the test signal.

[0081] Specifically, the isolation devices include differential isolation transformers and optocouplers connected in parallel;

[0082] The input terminal of the differential isolation transformer is connected to the output terminal of the signal source module 101, and the output terminal is connected to the input terminal of the isolation module 103, for transmitting high-bandwidth test signals;

[0083] The input terminal of the optocoupler is connected to the output terminal of the signal source module 101, and the output terminal is connected to the input terminal of the isolation module 103, for transmitting low-speed control signals;

[0084] A phase matching circuit is provided between the differential isolation transformer and the optocoupler to ensure that the signal transmission delays of the two are consistent.

[0085] The isolation devices are refined into parallel differential isolation transformers and optocouplers, and a phase matching circuit is added. This not only takes into account the transmission characteristics of different types of signals, but also solves the timing consistency problem of multi-path transmission.

[0086] First, the connection method between the differential isolation transformer and the signal source module 101 and isolation module 103 determines that it is specifically used for transmitting high-bandwidth test signals. It should be noted that the sinusoidal signal (especially the power frequency signal containing harmonic components) in the metering analog-to-digital converter test is a high-bandwidth analog signal, which has high requirements for the bandwidth and linearity of the transmission path. The differential isolation transformer transmits the signal through magnetic coupling, which has the characteristics of high bandwidth and good linearity, and can effectively preserve the spectral characteristics of the sinusoidal signal. Its specifications can be selected according to the frequency range of the test signal. For example, for a 50Hz power frequency signal and harmonic components, a differential isolation transformer with a bandwidth covering 10Hz-1MHz can be selected. This embodiment does not impose strict limitations on this.

[0087] Secondly, optocouplers are designed for the transmission of low-speed control signals. Generally, in addition to test signals, there may be low-speed control signals (such as signal range switching commands, channel selection signals, etc.) between the signal source module 101 and the analog-to-digital converter module 102. These signals have low bandwidth requirements but high isolation and reliability requirements. Optocouplers transmit information through optical signals, offering advantages such as high isolation voltage and strong anti-interference capabilities, perfectly suited to the transmission needs of low-speed control signals. It should be noted that the transmission rate of the optocoupler does not need to match the bandwidth of the test signal; typically, kbps is sufficient for control signal transmission. This does not mean that it needs to maintain the same performance parameters as the differential isolation transformer.

[0088] It should also be noted that the differential isolation transformer and optocoupler are connected in parallel to achieve parallel transmission of test and control signals, avoiding signal aliasing or bandwidth limitations caused by a single isolation path. However, parallel transmission may introduce new problems: the two devices have inherent differences in transmission delay (the transformer, based on magnetic coupling, typically has a delay in the nanosecond range; the optocoupler, based on optical conversion, typically has a delay in the microsecond range). If not corrected, this can lead to timing misalignment between the control and test signals, affecting test synchronization. Therefore, the phase matching circuit compensates for the transmission delay difference between the two isolation devices, ensuring that the high-bandwidth test signal and the low-speed control signal arrive synchronously at the analog-to-digital converter module 102. This can be achieved in several ways: it can be a resistor-capacitor (RC) delay network, adding a fixed delay to the shorter path by adjusting the resistor and capacitor parameters; it can be a programmable delay chip, dynamically compensating for the delay difference through software configuration; or it can be a phase-locked loop-based synchronization circuit, tracking and correcting the phase deviation between the two signals in real time. It should be noted that the accuracy of the phase matching circuit should be designed according to the test synchronization requirements.

[0089] Based on the above, the differential isolation transformer in this embodiment ensures the high-fidelity transmission of high-bandwidth test signals, the optocoupler ensures reliable isolation of low-speed control signals, and the phase matching circuit solves the timing consistency problem of parallel transmission. This combination can adapt to the transmission characteristics of different signals and ensure the synchronization of multiple signal transmissions, making it particularly suitable for scenarios where analog test signals and digital control signals coexist in the testing of analog-to-digital converters for metering.

[0090] According to the above embodiments, in one specific embodiment, the interface structure of the analog-to-digital converter module 102 is a multi-layer stacked adapter socket.

[0091] The multi-layer stacked adapter socket includes at least two layers of socket units for adapting analog-to-digital converters under test with different package types, and each socket unit is stacked along the height direction of the analog-to-digital converter module 102;

[0092] Each socket unit is connected to the internal signal channel of the analog-to-digital converter module 102 through an adjustable pin mapping component. The adjustable pin mapping component is used to enable the corresponding conduction of the pins of the analog-to-digital converters under test with the internal signal channel for different packages.

[0093] In this specific embodiment, the interface structure of the analog-to-digital converter module 102 is defined as a multi-layer stacked adapter socket, and flexible adaptation is achieved through an adjustable pin mapping component, which not only solves the compatibility problem of ADCs with different packages, but also maintains the compactness of the structure.

[0094] First, the multi-layer stacked adapter socket contains at least two layers of socket units, which are stacked along the height direction. The core purpose of this structural design is to achieve compatibility of multiple encapsulation types within a limited space.

[0095] It should be noted that analog-to-digital converters in the metering field come in various package forms, such as dual in-line package (DIP), quad flat package (QFP), and ball grid array package (BGA). The number of pins, spacing, and arrangement of different packages vary greatly, so a single socket is difficult to adapt to all types.

[0096] By using a stacked design, socket units compatible with different packages can be integrated into the same module. For example, the bottom layer can have a BGA socket (for high-density pin ADCs), the middle layer a QFP socket (for medium-density pin ADCs), and the top layer a DIP socket (for low-density pin ADCs). This allows for multi-scenario testing needs to be met without replacing the entire adapter module. Furthermore, the stacking height can be adjusted according to actual requirements and is not limited to two layers. If more package types need to be accommodated, the number of stacking layers can be increased; this embodiment does not impose strict limitations on this.

[0097] Secondly, each socket unit is connected to the internal signal channel via an adjustable pin mapping component. Although the functional pins (such as analog input, power supply, ground, and digital output) of different packaged ADCs have the same function, their physical pin numbers often differ. The adjustable pin mapping component establishes a dynamic mapping relationship, accurately mapping the functional pins of different packaged ADCs to the internal signal channel of the analog-to-digital converter module 102 (e.g., mapping all analog input pins of all ADCs to the internal test signal channel). This can be achieved in several ways: it can be a miniature DIP switch array, where the pin correspondence is set manually by adjusting the positions; it can be a programmable logic device, such as a Complex Programmable Logic Device (CPLD) or a Field-Programmable Gate Array (FPGA), where the pin mapping is automatically switched via software configuration; or it can be a replaceable pin adapter board, with a customized mapping relationship for a specific package.

[0098] It's important to note that the use of adjustable pin mapping components with multi-layer stacked sockets does not mean that a separate set of components must be configured for each socket unit. In practical applications, all socket units can be connected to the internal signal channels through the same set of adjustable pin mapping components. When switching between socket units on different layers, only the configuration of the mapping component needs to be adjusted; no changes to the hardware connections are required. In other words, the stacking structure solves the physical compatibility problem, while the mapping component solves the logical correspondence problem.

[0099] Based on the above principles, the interface structure design offers several advantages: First, it boasts high space utilization, avoiding the dispersed layout of multiple independent adapter modules through a stacking design, which aligns with the integration concept of the modular chassis 106. Second, it offers strong adaptability, allowing for quick adaptation to new ADC packages by replacing the socket unit (or increasing the number of stacking layers) and adjusting the mapping components, thus extending the device's lifespan. Third, it provides excellent operational convenience, requiring only the replacement of the socket layer and adjustment of the mapping configuration when testing ADCs with different packages, eliminating the need for rewiring or calibration and improving testing efficiency.

[0100] Furthermore, multi-layer stacked adapter sockets can be used with locking mechanisms (such as clips or screw mounts) to enhance connection reliability and prevent poor contact of the ADC due to vibration or insertion / removal during testing. For leadless packages such as BGA, the socket unit can use a ball-and-socket structure or flexible probes to ensure the stability of the electrical connection.

[0101] Specifically, the adjustable pin mapping component is a miniature DIP switch;

[0102] The input terminal of the miniature DIP switch is connected to the pin of the multi-layer stacked adapter socket, and the output terminal is connected to the internal signal channel of the analog-to-digital converter module 102. By adjusting the position of the miniature DIP switch, the connection between different socket units in the multi-layer stacked adapter socket and the internal signal channel can be switched to adapt to the corresponding packaged analog-to-digital converter under test.

[0103] The input terminal of the miniature DIP switch connects to the pins of the multi-layer stacked adapter socket, and the output terminal connects to the internal signal channel of the analog-to-digital converter module 102. Each pin of the multi-layer stacked adapter socket corresponds to the physical pins of different packaged ADCs, while the internal signal channel corresponds to the device's functional signals (such as test signal input channel, power channel, ground channel, digital output channel, etc.). Therefore, the function of the miniature DIP switch is to establish the correspondence between physical pins and functional channels. For example, when testing a DIP-packaged ADC, its "pin 3" is an analog input, and the DIP switch connects this pin to the internal "test signal input channel"; when testing a QFP-packaged ADC, its "pin 15" is an analog input, and the DIP switch also connects this pin to the "test signal input channel," thus achieving a unified correspondence between the functional pins of different packaged ADCs and the internal channels of the device.

[0104] Connection switching is achieved by adjusting the positions of the miniature DIP switches. Testers only need to manually switch the corresponding positions according to the pin definition table of the ADC under test to complete the mapping configuration. No software programming or special tools are required, making it particularly suitable for scenarios where test objects can be quickly changed on-site.

[0105] It should also be noted that the use of miniature DIP switches with multi-layer stacked adapter sockets does not mean that each set of DIP switches corresponds to only a single socket unit. In practical applications, a reuse design can be adopted. The same set of DIP switches can be connected to the pins of socket units on different stacked layers through a mechanical switching mechanism (such as a sliding switch). When switching to a certain layer of sockets, the DIP switch automatically conducts to the pins of that layer, eliminating the need to configure a complete set of DIP switches for each layer of sockets, thereby simplifying the structure and reducing costs.

[0106] According to the above embodiments, in one specific embodiment, the signal switching switch is a dual-redundant solid-state switch array;

[0107] The input terminal of the dual redundant solid-state switch array is connected to the output terminal of the signal source module 101, and the output terminal is connected to the input terminal of the isolation module 103.

[0108] An RC soft-start network is provided between the input terminal of the dual redundant solid-state switch array and the signal source module 101, and between the output terminal of the dual redundant solid-state switch array and the isolation module 103. The RC soft-start network is used to reduce the voltage surge during signal switching.

[0109] In this specific embodiment, the signal switching switch is defined as a dual-redundant solid-state switch array, and an RC soft-start network is added, which not only ensures the stability of signal switching, but also avoids the impact of the switching process on subsequent modules.

[0110] First, the input terminal of the dual redundant solid-state switch array is connected to the signal source module 101 to obtain a sine wave signal or a DC signal, and the output terminal is connected to the isolation module 103 to transmit the selected signal, thereby realizing the switching function of the two test signals.

[0111] It's important to note that dual redundancy design means each switching channel contains at least two parallel solid-state switching devices, such as metal-oxide-semiconductor field-effect transistors (MOSFETs) or insulated-gate bipolar transistors (IGBTs). This ensures that signal transmission is not affected by the failure of a single device, improving reliability. When a single device fails due to a fault, the redundant devices can continue to maintain channel conduction, preventing signal transmission interruption. Furthermore, solid-state switches offer advantages over mechanical relays, including no contacts, fast switching speeds (typically in the nanosecond to microsecond range), and long lifespans (theoretically no mechanical wear), making them suitable for high-frequency signal switching scenarios. However, this does not mean that only specific types of solid-state devices can be used.

[0112] Secondly, the RC soft-start network addresses the voltage surge issue during signal switching. Generally, the DC or sinusoidal signal output by the signal source module 101 has a certain amplitude (e.g., 0-10V). When the switching array suddenly turns on, the impedance change in the signal path can cause a voltage step, forming a transient surge current. This surge can interfere with the normal operation of the isolation module 103 and even damage the input of the ADC under test (especially since the input stage of high-precision ADCs is often quite fragile). The RC soft-start network (composed of a resistor R and a capacitor C) smooths the voltage step through the RC charging and discharging characteristics: during switching, the voltage across the capacitor cannot change abruptly, and the resistor limits the initial current, allowing the output voltage to rise slowly to a stable value, thereby reducing the surge intensity. Its parameters can be designed according to the signal amplitude and load characteristics; this embodiment does not impose strict limitations on this. Specifically, the RC soft-start network consists of a 10Ω resistor and a 100nF capacitor, extending the voltage rise time during signal switching to approximately 50μs, thus avoiding a surge to the ADC input.

[0113] It should be noted that the RC soft-start network is set at both the input and output ends of the switch array to achieve bidirectional protection. The input network can suppress voltage fluctuations on the signal source side from being transmitted to subsequent links through the switch array, while the output network directly protects the isolation module 103 and the ADC under test, avoiding interference caused by reflected voltage at the moment the switch is turned on.

[0114] In addition, the dual-redundant solid-state switch array can be used in conjunction with fault detection circuits (such as current sensors or voltage comparators) to monitor the switch status in real time. When a single device failure is detected, an alarm signal can be sent to the host computer via an indicator light or transmission module 105, which facilitates timely maintenance and further improves the availability of the device.

[0115] According to the above embodiments, in one specific embodiment, the backplane bus is a three-layer symmetrical printed circuit board structure, including signal layers on both sides and a power layer in the middle.

[0116] The signal layer is connected to the signal pins of the signal source module 101, analog-to-digital converter module 102, isolation module 103, calibration module 104, and transmission module 105 for transmitting test signals and control commands.

[0117] The power layer is connected to the power pins of each module to supply power to each module.

[0118] This specific embodiment defines the backplane bus as a three-layer symmetrical printed circuit board structure and refines the functional division of the signal layer and power layer, which not only ensures the integrity of signal transmission but also improves the stability of power supply.

[0119] First, the characteristic of a three-layer symmetrical printed circuit board structure is that the two sides are signal layers and the middle is a power layer. The primary purpose of this symmetrical design is to optimize electromagnetic compatibility.

[0120] As a common transmission path for signals and power of various modules, the backplane bus is susceptible to electromagnetic interference between internal modules (such as interference from high-frequency signals in the signal layer to the power layer) and external environmental interference. The symmetrical structure can form an electromagnetic shielding barrier through the intermediate power layer. The power layer is usually grounded or connected to a stable DC voltage, which can effectively isolate crosstalk between the signal layers on both sides and reduce the impact of external interference on the signal layer.

[0121] In addition, the symmetrical structure is also conducive to the mechanical stress balance of the printed circuit board, reduces the risk of deformation caused by temperature changes, and ensures the stability of the connection between the module and the backplane (such as the reliability of the gold finger insertion). It does not mean that it is limited to a three-layer structure. If the shielding effect needs to be enhanced, a ground layer can be added to form a five-layer or seven-layer structure. This embodiment does not impose strict limitations on this.

[0122] Secondly, the signal layer connects to the signal pins of each module, undertaking the transmission of test signals and control commands. Generally, the signal layer needs to distinguish between analog signal paths and digital signal paths: analog signal paths (such as sinusoidal / DC test signals output from a signal source) should use differential routing (impedance matched to 50Ω or 100Ω) to reduce transmission loss and noise coupling; digital signal paths (such as control commands and status feedback signals between modules) can use single-ended routing, avoiding intersections with analog signal paths through proper layout. The wiring density of the signal layer needs to match the number of signal pins in each module. For example, the high-speed data channel of transmission module 105 may require multiple differential pairs, requiring sufficient space to be reserved in the signal layer to ensure signal integrity.

[0123] Furthermore, the power layer connects to the power pins of each module, and its core function is to provide a unified and stable power supply for the entire device. It should be noted that different modules may have different power requirements (e.g., signal source module 101 may require ±15V analog power, while transmission module 105 may require 3.3V digital power). Therefore, the power layer can be divided into multiple independent areas, with copper foil used for segmentation to distribute power at different voltage levels and avoid interference between power supplies. Simultaneously, the power layer should have multiple grounding points, and reserved soldering positions for filter capacitors at critical nodes (such as the power input points of each module) to suppress power supply noise and ensure a low-ripple, stable voltage for each module.

[0124] The three-layer structure achieves this separation through physical partitioning, significantly improving signal transmission quality compared to single-layer or double-layer boards where signal and power are mixed. For example, the three-layer symmetrical PCB for the backplane bus can use FR-4 substrate, with differential line length matching error of less than 5 mil for the signal layers. High-permeability absorbing material is embedded in the power layer to absorb electromagnetic interference in the 20MHz–1GHz range; this structure reduces inter-module crosstalk by more than 30%.

[0125] Specifically, the signal source module 101 is installed on the left side of the chassis, the analog-to-digital conversion module is located in the middle, and the transmission module 105 and calibration module 104 are located on the right side. All modules are connected to the backplane via hot-swappable gold fingers. The signal layer on the backplane uses 100Ω differential traces, the power layer uses a four-point grounding distribution, and the electromagnetic shielding cavity of the isolation module 103 is an aluminum-magnesium alloy shell that forms a complete Faraday cage with the chassis.

[0126] According to the above embodiments, in one specific embodiment, the transmission module 105 includes a microcontroller control channel, a high-speed data channel, and a synchronous trigger logic circuit;

[0127] One end of the microcontroller's control channel is connected to the backplane bus, and the other end is connected to an external host computer via an isolation bus to transmit control commands issued by the host computer.

[0128] One end of the high-speed data channel is connected to the output of the analog-to-digital converter under test, and the other end is connected to an external host computer through an isolation bus to transmit the conversion data output by the analog-to-digital converter under test.

[0129] The synchronous triggering logic circuit is connected to the microcontroller control channel and the high-speed data channel respectively, and is used to keep the transmission timing of control commands and conversion data aligned.

[0130] In this specific embodiment, the transmission module 105 is further subdivided into a microcontroller control channel, a high-speed data channel, and a synchronous triggering logic circuit, which not only solves the differentiated transmission requirements of different types of data, but also ensures the consistency of transmission timing.

[0131] First, the connection logic of the microcontroller unit (MCU) control channel determines its core function: receiving control commands (such as signal source frequency adjustment, calibration triggering, channel switching, etc.) from the host computer via the backplane bus and distributing them to various modules. It should be noted that control commands are typically low-speed, low-bandwidth signals (such as serial port commands or Ethernet control frames), with low requirements for transmission rate but stringent reliability requirements. Therefore, the MCU control channel can adopt mature solutions based on Universal Asynchronous Receiver / Transmitter (UART) or Ethernet controllers, using verification mechanisms (such as cyclic redundancy check) to ensure error-free command transmission.

[0132] In addition, this channel can also transmit the status information of each module in reverse (such as the output status of the signal source and the calibration completion flag), forming a two-way control closed loop of "host computer-device". This does not mean that only a single communication protocol can be used. It can be flexibly selected according to the host computer interface type (such as USB or Ethernet).

[0133] Secondly, the high-speed data channel's connection method makes it specifically designed for transmitting data converted by the analog-to-digital converter under test. The high-speed data channel requires a dedicated high-speed interface, such as Low Voltage Differential Signaling (LVDS), High-Speed ​​Full-Duplex Synchronous Serial Communication Protocol (SPI), or Gigabit Ethernet, and must be used in conjunction with a data buffer unit (such as a FIFO memory) to temporarily store the converted data before uploading it in batches to the host computer, ensuring continuous data transmission.

[0134] Synchronous triggering logic circuits are used to solve the timing alignment problem between control commands and conversion data. In ADC testing, control commands (such as start sampling) and corresponding conversion data must maintain a strict time correlation; otherwise, mismatches between test data and control parameters will occur (e.g., the host computer has adjusted the signal source frequency, but the ADC data still corresponds to the original frequency). Synchronous triggering logic circuits generate unified synchronization pulses to control the instruction parsing time of the MCU control channel and the data buffer refresh time of the high-speed data channel, ensuring that both operate based on the same time reference.

[0135] There are several ways to implement it: it can be a clock synchronization circuit based on a phase-locked loop (PLL), which divides the external reference clock and uses it as a synchronization reference; it can also be a programmable timer, which coordinates the timing of the two channels by setting a preset delay parameter; or it can directly use the synchronization signal sent by the host computer as the trigger source to ensure that the global time of the device is consistent with that of the host computer.

[0136] For example, the synchronization triggering logic circuit of the transmission module 105 can be implemented by an FPGA. Each time the MCU issues a test command, the FPGA generates a synchronization pulse to control the start of Ethernet frames (1000BASE-T) and USB 3.0 frames, ensuring that the data packet time alignment deviation is less than 100ns. This structure ensures that the sampled data received by the host computer corresponds one-to-one with the control signals.

[0137] In addition, an optical fiber interface can be added to the transmission module 105 to establish a long-distance connection with the host computer with low latency and high anti-interference.

[0138] According to the above embodiments, in one specific embodiment, the input terminal of the automatic calibration switch is connected to the output terminal of the reference voltage source, and the output terminal is connected to the signal generation unit of the signal source module 101; by switching the on / off state of the automatic calibration switch, the standard voltage signal of the reference voltage source can be selectively connected to the signal source module 101 to calibrate the sinusoidal signal or DC signal output by the signal source module 101.

[0139] In this specific embodiment, the input terminal of the automatic calibration switch is connected to a reference voltage source, and the output terminal is connected to the signal generation unit of the signal source module 101. The reference voltage source provides a standard voltage signal (such as a reference value of 1V, 2.5V, 5V, etc.) that has been metrologically certified, and its accuracy is usually higher than the output accuracy of the signal source module 101, serving as a calibration reference. The signal generation unit is the core component of the signal source module 101 that generates sinusoidal or DC signals, such as a direct digital frequency synthesis (DDS) chip or a reference source circuit. By connecting the standard voltage signal to this unit, a calibration coefficient can be generated and the output corrected by comparing the deviation between the "standard value" and the "actual output value of the signal source," thereby improving the accuracy of the signal source.

[0140] Secondly, selective calibration is achieved by switching the on / off state of the automatic calibration switch. The output characteristics of the signal source module 101 will drift with factors such as time and temperature, but frequent calibration will interrupt the normal testing process. Therefore, the on / off state of the automatic calibration switch can be controlled in two ways: one is timed triggering (e.g., automatically turning on once per hour) to periodically correct drift; the other is on-demand triggering (e.g., turning on when the host computer issues a calibration command) to ensure signal accuracy before critical testing stages. When the switch is off, the signal source module 101 outputs the test signal normally; when the switch is on, the calibration link starts, and automatically disconnects after calibration is completed, without affecting subsequent tests, and does not mean that it must be kept in a constantly on state.

[0141] It should be noted that the selective connection of the automatic calibration switch is applicable to both DC signal calibration and sinusoidal signal calibration.

[0142] In addition, the automatic calibration switch can be used in conjunction with the sampling feedback circuit: when the switch is on, the signal generation unit obtains the standard value of the reference voltage source and its own output value through internal AD sampling, calculates the deviation and automatically updates the calibration parameters; after calibration is completed, the switch is off, and the signal source module 101 outputs a signal based on the updated parameters, forming a sampling-comparison-correction closed-loop calibration mechanism.

[0143] According to the above embodiments, in one specific embodiment, the signal source module 101 includes a sinusoidal signal source unit, which is composed of a direct digital frequency synthesis chip, a multi-segment programmable filter and a digital predistortion compensation subunit connected in sequence.

[0144] The output of the direct digital frequency synthesizer chip is connected to the input of a multi-segment programmable filter to generate a basic sine wave signal.

[0145] The output of the multi-segment programmable filter is connected to the input of the digital predistortion compensation subunit for filtering the basic sine signal.

[0146] The output of the digital predistortion compensation subunit is connected to the input of the signal switching switch. It is used to load the spectrum correction coefficient to correct the harmonic components of the signal, so that the output sinusoidal signal conforms to the characteristics of the power system frequency signal.

[0147] In this specific embodiment, a Direct Digital Frequency Synthesis (DDS) chip serves as the signal generation source. Its output is connected to a multi-segment programmable filter, and its core function is to generate a high-precision fundamental sine wave signal. It should be noted that the DDS chip achieves signal synthesis through a digital phase accumulator and waveform memory, featuring high frequency resolution (typically up to the μHz level) and fast frequency switching (ns level). It can accurately generate 50Hz or 60Hz power frequency signals, solving the problems of low frequency accuracy and inconvenient adjustment in traditional analog oscillators. This does not mean it is limited to a specific model; any chip capable of high-precision power frequency synthesis is acceptable.

[0148] Secondly, a multi-stage programmable filter is connected between the DDS chip and the digital predistortion compensation subunit. Its function is to filter the basic sinusoidal signal and suppress the spurious signals inherent in the DDS chip. Generally speaking, the basic sinusoidal signal output by the DDS chip will contain spurious harmonics caused by digital quantization and phase truncation, which can interfere with the dynamic performance testing of the ADC.

[0149] For example, the DDS chip in the sinusoidal signal source unit can be a 14-bit resolution AD9957, with an output frequency range covering 10Hz to 100kHz. The multi-segment programmable filter adopts a five-stage elliptic filter structure, and the cutoff frequency can be adjusted to 50Hz or 60Hz via the MCU. The spectrum correction coefficients stored in the digital predistortion compensation subunit are downloaded to the FPGA via the host computer and automatically updated each time the output frequency is switched, so as to compensate for harmonic distortion not exceeding -90dBc.

[0150] The implementation can be a switched capacitor filter array or an active filter bank based on operational amplifiers, with the switching of filter segments controlled by instructions from the host computer. This embodiment does not impose strict limitations on this.

[0151] The digital predistortion compensation subunit is connected between the filter and the signal switching switch. Its core function is to apply spectral correction coefficients to correct the harmonic components of the signal, making them conform to the characteristics of the power system's power frequency signal. The digital predistortion compensation subunit performs reverse correction of the signal's harmonic components through a preset correction algorithm.

[0152] Based on the above principles, the three-stage processing link DDS chip ensures that the frequency error of the power frequency signal is within the allowable range. The combination of filters and pre-distortion compensation significantly suppresses spurious signals and harmonics, avoiding interference with the dynamic performance testing of the ADC. Pre-distortion compensation makes the signal characteristics closer to the real power system. This provides a real and reliable signal source basis for the dynamic performance testing of metering ADCs.

[0153] The above provides a detailed description of the metering analog-to-digital converter testing device for the present invention. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0154] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A metering analog-to-digital converter testing device, characterized in that, include: The system includes a signal source module (101), an analog-to-digital converter module (102), an isolation module (103), a calibration module (104), a transmission module (105), and a modular chassis (106) for outputting sinusoidal or DC signals in a preset frequency band. The modular chassis (106) is equipped with a backplane bus, and the signal source module (101), the analog-to-digital converter module (102), the isolation module (103), the calibration module (104) and the transmission module (105) are all connected to the backplane bus; The output of the signal source module (101) is connected to the input of the isolation module (103) via a signal switching switch; the analog-to-digital converter module (102) is detachably connected to the modular chassis (106), and the signal input of the analog-to-digital converter module (102) is connected to the output of the isolation module (103); The analog-to-digital converter (102) is provided with an interface structure adapted to the analog-to-digital converter under test. The analog-to-digital converter under test is connected to the analog-to-digital converter (102) through the interface structure to receive the test signal transmitted through the isolation module (103); and the output terminal of the analog-to-digital converter under test is connected to the transmission module (105). The calibration module (104) includes a reference voltage source and an automatic calibration switch, wherein the reference voltage source is connected to the signal source module (101) through the automatic calibration switch; The transmission module (105) is connected to an external host computer via an isolation bus.

2. The metering analog-to-digital converter testing device according to claim 1, characterized in that, The isolation module (103) includes an electromagnetic shielding cavity and an isolation device; The electromagnetic shielding cavity is installed outside the signal output channel of the signal source module (101) and the signal input channel of the analog-to-digital converter module (102); The isolation device is connected in series between the signal source module (101) and the analog-to-digital converter module (102).

3. The metering analog-to-digital converter testing device according to claim 2, characterized in that, The isolation device includes a differential isolation transformer and an optocoupler connected in parallel; The input terminal of the differential isolation transformer is connected to the output terminal of the signal source module (101), and the output terminal is connected to the input terminal of the isolation module (103) for transmitting high-bandwidth test signals. The input end of the optocoupler is connected to the output end of the signal source module (101), and the output end is connected to the input end of the isolation module (103) for transmitting low-speed control signals; A phase matching circuit is provided between the differential isolation transformer and the optocoupler, and the phase matching circuit is used to keep the signal transmission delay of the two consistent.

4. The metering analog-to-digital converter testing device according to claim 1, characterized in that, The interface structure of the analog-to-digital converter module (102) is a multi-layer stacked adapter socket; The multi-layer stacked adapter socket includes at least two layers of socket units for adapting analog-to-digital converters of different package types to be tested, and each of the socket units is stacked along the height direction of the analog-to-digital converter module (102). Each of the socket units is connected to the internal signal channel of the analog-to-digital converter module (102) through an adjustable pin mapping component. The adjustable pin mapping component is used to enable the corresponding conduction of the pins of the analog-to-digital converters under test with the internal signal channel for different packages.

5. The metering analog-to-digital converter testing device according to claim 4, characterized in that, The adjustable pin mapping component is a miniature DIP switch; The input terminal of the miniature DIP switch is connected to the pin of the multi-layer stacked adapter socket, and the output terminal is connected to the internal signal channel of the analog-to-digital converter module (102). By adjusting the position of the miniature DIP switch, the connection between different socket units in the multi-layer stacked adapter socket and the internal signal channel can be switched to adapt to the corresponding packaged analog-to-digital converter under test.

6. The metering analog-to-digital converter testing device according to claim 1, characterized in that, The signal switching switch is a dual-redundant solid-state switch array; The input terminal of the dual redundant solid-state switch array is connected to the output terminal of the signal source module (101), and the output terminal is connected to the input terminal of the isolation module (103). An RC soft-start network is provided between the input terminal of the dual redundant solid-state switch array and the signal source module (101), and between the output terminal of the dual redundant solid-state switch array and the isolation module (103). The RC soft-start network is used to reduce the voltage surge during signal switching.

7. The metering analog-to-digital converter testing device according to claim 1, characterized in that, The backplane bus has a three-layer symmetrical printed circuit board structure, including signal layers on both sides and a power layer in the middle. The signal layer is connected to the signal pins of the signal source module (101), analog-to-digital converter module (102), isolation module (103), calibration module (104), and transmission module (105) for transmitting test signals and control commands; The power layer is connected to the power pins of each module and is used to supply power to each module.

8. The metering analog-to-digital converter testing device according to claim 1, characterized in that, The transmission module (105) includes a microcontroller control channel, a high-speed data channel, and a synchronous trigger logic circuit; One end of the microcontroller control channel is connected to the backplane bus, and the other end is connected to an external host computer through the isolation bus, for transmitting control commands issued by the host computer. One end of the high-speed data channel is connected to the output of the analog-to-digital converter under test, and the other end is connected to an external host computer through the isolation bus to transmit the conversion data output by the analog-to-digital converter under test. The synchronous triggering logic circuit is connected to the microcontroller control channel and the high-speed data channel respectively, and is used to synchronously control the transmission timing of the control commands and the converted data to keep them aligned.

9. The metering analog-to-digital converter testing device according to claim 1, characterized in that, The input terminal of the automatic calibration switch is connected to the output terminal of the reference voltage source, and the output terminal is connected to the signal generation unit of the signal source module (101). By switching the on / off state of the automatic calibration switch, the standard voltage signal of the reference voltage source can be selectively connected to the signal source module (101) to calibrate the sinusoidal signal or DC signal output by the signal source module (101).

10. The metering analog-to-digital converter testing device according to any one of claims 1-9, characterized in that, The signal source module (101) includes a sinusoidal signal source unit, which is composed of a direct digital frequency synthesis chip, a multi-segment programmable filter and a digital predistortion compensation subunit connected in sequence. The output of the direct digital frequency synthesis chip is connected to the input of the multi-segment programmable filter to generate a basic sine signal. The output of the multi-segment programmable filter is connected to the input of the digital predistortion compensation subunit, and is used to filter the basic sine signal. The output of the digital predistortion compensation subunit is connected to the input of the signal switching switch, and is used to load the spectrum correction coefficient to correct the harmonic components of the signal so that the output sinusoidal signal conforms to the characteristics of the power system frequency signal.

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