阅读说明：本技术 一种飞机直流270v供电系统畸变、脉动信号测试方法 (Distortion and pulsation signal testing method for airplane direct current 270V power supply system ) 是由 侯毅 王文健 程勤 柴艳丽 于 2021-04-13 设计创作，主要内容包括：本发明涉及一种飞机直流270V供电系统畸变、脉动信号测试方法,属于飞机供电特性测试与校准技术领域。本发明主要用于实现飞机直流270V供电系统畸变、脉动信号的准确测量,将飞机直流270V供电特性参数中畸变频谱、脉动电压幅度溯源至基本量。本发明将被测叠加在直流270V上的畸变、脉动信号与高稳定直流270V参考信号通过高压线性放大器构成的减法电路相减,得到较小的畸变、脉动信号；该信号满足具有正负信号测量的A/D转换器的输入范围；同时,通过对高稳定直流参考信号和减法电路幅频特性的校准,实现对测量得到的畸变、脉动值进行补偿修正。(The invention relates to a method for testing distortion and pulsation signals of an airplane direct-current 270V power supply system, and belongs to the technical field of airplane power supply characteristic testing and calibration. The method is mainly used for accurately measuring the distortion and the pulse signals of the airplane direct current 270V power supply system and tracing the distortion frequency spectrum and the pulse voltage amplitude in the airplane direct current 270V power supply characteristic parameters to basic quantities. According to the invention, a measured distortion and pulsation signal superposed on a direct current 270V is subtracted from a high-stability direct current 270V reference signal through a subtraction circuit formed by a high-voltage linear amplifier to obtain a smaller distortion and pulsation signal; the signal satisfies the input range of an A/D converter with positive and negative signal measurements; meanwhile, the measured distortion and pulsation values are compensated and corrected by calibrating the amplitude-frequency characteristics of the high-stability direct-current reference signal and the subtraction circuit.)

1. A method for testing distortion and pulsation signals of an airplane direct current 270V power supply system is characterized by comprising the following steps: the method comprises the following specific steps:

step one, a direct current high-stability reference signal source outputs a high-stability direct current reference signal;

subtracting the direct current high-stability reference signal from the measured signal through a subtraction circuit to obtain distortion and pulse signals meeting the input range of the A/D converter; as shown in fig. 2;

step three, the A/D converter measures the values V of the distortion and pulsation signals_n；

Step four, calibrating the subtraction circuit by using standard 270V direct current distortion and pulse signals to obtain calibration data x_nAnd compensating and correcting the distortion and the pulsation signal value through the calibration data.

The standard 270V DC distortion and pulsation signal V is measured by a subtraction circuit_nSaid signal V_nCorresponding standard distortion and pulsation value x_nN is a frequency point;

since the subtraction circuit uses a linear amplifier, the correction coefficient of the frequency point is:

by a correction factor k_nMeasuring the measured 270V DC distortion and pulsation signal y obtained in the second step_nPerforming compensation correction to obtain a corrected result U_nComprises the following steps:

U_n＝k_n×y_n

and accurate measurement of distortion and pulse signals is realized.

2. An apparatus for implementing the method of claim 1, wherein: the method comprises the following steps: the high-stability direct-current reference signal source, the subtraction circuit formed based on the high-voltage linear amplifier and the A/D converter are connected with the output end of the high-voltage linear amplifier;

the direct current high-stability reference signal source is used for generating a high-stability direct current reference signal and consists of a high-stability reference source and an independent high-voltage linear amplifier. As shown in fig. 3;

the subtraction circuit formed based on the high-voltage linear amplifier is used for subtracting a 270V direct-current power supply characteristic signal to be measured from a high-stability direct-current reference signal to obtain an input range distortion and a pulse signal of the ADC meeting the positive and negative signal measurement requirements.

3. The method of claim 1, wherein: step three, the A/D converter is used for measuring the value V of the distortion and pulsation signals_n。

Technical Field

The invention relates to a method for testing distortion and pulsation signals of an airplane direct-current 270V power supply system, and belongs to the technical field of airplane power supply characteristic testing and calibration.

Background

The 270V DC power supply system of the airplane is the main power supply system of a new generation of fighters, and the existing 115V/400Hz AC power supply system is replaced to a great extent. The method is characterized in that: the brushless direct current generator has simple structure, reliable work and convenient parallel connection; the internal loss of the main power supply and the secondary power supply is small, and the efficiency is high; the parallel connection is realized through the reverse flow protection diode, and the power supply interruption caused by the failure of the main power supply can be avoided; the power grid has light weight; the harm of 270V direct current to human bodies is less than that of 115V/400Hz alternating current; brushless starting power generation can be realized. Factors that cause distortion in the aircraft power supply system include the use of onboard generators, digital switching circuits, switching power supplies, and various rotating electrical machines. Factors that cause the ripple include regulation of the dc supply voltage, internal commutation or rectification of the dc supply, and load variations, among others. The quality of an airborne power supply is directly influenced by the sizes of distortion and pulse signals in an airplane power supply system, and the normal work of airborne electric equipment is greatly influenced. The existing airplane power supply characteristic testing device established for the 270V direct current power supply system lacks corresponding metering guarantee in the aspect of magnitude traceability, and particularly cannot effectively trace the source of distortion and pulsation signal parameters.

The dc distortion refers to an ac component contained in the dc voltage. The ratio of the magnitude of the dc distortion to the steady-state dc voltage is called the dc voltage distortion coefficient, and the root mean of each frequency component of the dc distortion is the distortion frequency spectrum. The distorted signal of the aircraft DC 270V power supply system is shown in FIG. 1. The essence is to superimpose several smaller ac signals on a 270V dc voltage. According to the relevant standard, the frequency range of the distorted signal is: 10Hz to 100 kHz; the amplitude range is: 0.079V-3.162V. Ripple refers to the variation of instantaneous voltage around steady-state dc voltage during steady-state operation of the power supply system. The difference between the instantaneous voltage and the steady-state dc voltage is referred to as the ripple voltage amplitude. The pulsating voltage signal of the airplane direct current 270V power supply system is similar to a distortion signal, and is an alternating current small amplitude signal superposed on the 270V direct current voltage, and the frequency range is as follows: 1.2 kHz-16.8 kHz, the range of the pulse voltage amplitude is as follows: 0.24V-3.16V. Through the analysis, the main characteristic of the distortion and pulsation signals of the airplane direct current 270V power supply system is that a relatively small alternating current signal (minimum to 0.079V) is superposed on a relatively large direct current signal (270V), and finally, a relatively small alternating current signal needs to be directly measured (as shown in figure 1).

At present, distortion and pulsation signals of an airplane direct current 270V power supply system are measured by adopting a broadband voltage divider to attenuate unseparated direct current and alternating current signals at the same time, then a data acquisition system is adopted to measure the attenuated signals, and the obtained measurement data is subjected to alternating current and direct current separation in a mathematical calculation mode to further obtain values of the distortion and pulsation signals. Such methods usually use voltage dividers with large voltage division ratios (usually 40: 1) to satisfy the range of data collectors, which may result in measurement distortion, reduced resolution of the pulse signal, and even distortion and pulse signals at certain frequency points which cannot be measured because the amplitude is too small. Meanwhile, the bandwidth limitation of the voltage divider also has different degrees of influence on distortion and pulse signals, which causes larger errors to measurement results.

Disclosure of Invention

The invention aims to solve the problem of inaccurate measurement in the prior art, and provides a method for testing distortion and pulse signals of an airplane direct-current 270V power supply system; the method is mainly used for accurately measuring the distortion and the pulsation signals of the airplane direct current 270V power supply system and tracing the distortion frequency spectrum and the pulsation voltage amplitude in the airplane direct current 270V power supply characteristic parameters to basic quantities. According to the invention, a measured distortion and pulsation signal superposed on a direct current 270V is subtracted from a high-stability direct current 270V reference signal through a subtraction circuit formed by a high-voltage linear amplifier to obtain a smaller distortion and pulsation signal; the signal shown satisfies the input range of an A/D converter with positive and negative signal measurements; meanwhile, the measured distortion and pulsation values are compensated and corrected by calibrating the amplitude-frequency characteristics of the high-stability direct-current reference signal and the subtraction circuit.

The purpose of the invention is realized by the following technical scheme.

A method for testing distortion and pulsation signals of an airplane direct current 270V power supply system comprises the following specific steps:

step one, a direct current high-stability reference signal source outputs a high-stability direct current reference signal;

and secondly, subtracting the direct current high-stability reference signal from the detected signal through a subtraction circuit to obtain distortion and pulse signals meeting the input range of the A/D converter. As shown in fig. 2;

step three, the A/D converter measures the values V of the distortion and pulsation signals_n；

Step four, calibrating the subtraction circuit by using standard 270V direct current distortion and pulse signals to obtain calibration data x_nAnd compensating and correcting the distortion and the pulsation signal value through the calibration data.

The standard 270V DC distortion and pulsation signal V is measured by a subtraction circuit_nSaid signal V_nCorresponding standard distortion and pulsation value x_nN is a frequency point;

since the subtraction circuit uses a linear amplifier, the correction coefficient of the frequency point is:

by a correction factor k_nMeasuring the measured 270V DC distortion and pulsation signal y obtained in the second step_nPerforming compensation correction to obtain a corrected result U_nComprises the following steps:

U_n＝k_n×y_n

and accurate measurement of distortion and pulse signals is realized.

The device for realizing the method comprises the following steps: the high-stability direct-current reference signal source, the subtraction circuit formed based on the high-voltage linear amplifier and the A/D converter. As shown in fig. 3.

The direct current high-stability reference signal source is used for generating a high-stability direct current reference signal and consists of a high-stability reference source and an independent high-voltage linear amplifier.

The subtraction circuit formed based on the high-voltage linear amplifier is used for subtracting a 270V direct-current power supply characteristic signal (including distortion and pulse signals) to be measured from a high-stability direct-current reference signal to obtain the distortion and pulse signals of the input range of the ADC meeting the measurement of positive and negative signals.

The A/D converter is used for measuring the values of the distortion and pulsation signals.

Advantageous effects

The method for testing the distortion and the pulsation signals of the airplane direct current 270V power supply system is used for accurately measuring the distortion and the pulsation signals of the airplane direct current 270V power supply system and ensuring the accuracy and the reliability of measured data. For airplane design and manufacturing departments, the method can be applied to an electric appliance parameter testing system of a power grid test bed, and the accuracy of the measurement of distortion and pulse signals of the testing system can be improved. For a test department, the method can be applied to an aircraft power grid quality monitoring system in a flight test, and real-time monitoring of distortion and pulse signals in the test flight process is guaranteed. For a metering department, the method can be applied to a power supply characteristic parameter calibration device, and the tracing problem of distortion and pulsation parameters can be solved.

Drawings

FIG. 1 illustrates the characteristics of an aircraft 270V DC distortion, pulsation signal;

FIG. 2 shows the distortion and ripple signals obtained by the subtraction circuit;

FIG. 3 illustrates the principle of a 270V DC distortion and pulsation signal testing method for an aircraft;

fig. 4 shows the principle of the 270V dc distortion and ripple signal test circuit of the aircraft.

Detailed Description

The invention is further described with reference to the following figures and examples.

Example 1

The 270V direct current power supply adaptability experimental equipment of the airborne product is an important testing device for evaluating the power supply quality of the airborne electric equipment adaptive to the airplane power supply. The main function of the device is to simulate the working state of the airplane power supply under various extreme conditions, so as to detect the capability of airborne electric equipment adapting to the airplane power supply. The calibration device for the equipment needs to calibrate and trace the various analog power signals generated by the equipment, which involves accurately measuring 270V direct current distortion and pulsation signals contained in the signals.

As shown in fig. 4, the distortion and ripple measurement part of the calibration apparatus is composed of a highly stable dc reference signal source, a subtraction circuit, and an a/D converter.

The high-stability direct-current reference signal source consists of a voltage reference and a composite linear amplification circuit. Through the adjustment of the gain of the amplifier, the output high-stability direct current reference signal is 270V. The voltage reference is a high stability voltage reference source ADR4550 with a temperature characteristic of 2 ppm/DEG C. In the amplifier part, because the maximum input offset voltage of the PA94 chip is 5mV, and the temperature drift is 50 muV/DEG C, the measurement requirement cannot be met, an internal-external ring cascade system is formed by the ADA4522 and the PA94 by adopting a composite linear amplifying circuit, and the output error of the power amplifying part caused by the input offset and the temperature drift is reduced. The maximum steady-state accuracy error of the amplification channel due to the input offset voltage is 5 μ V × 2.5 × 14 ═ 0.175 mV.

The subtraction circuit based on the high-voltage linear amplifier is composed of a high-voltage linear amplifier PA94, and the maximum allowable input voltage of the subtraction circuit is 350V. The 270V DC distortion and pulse signal to be measured is added to the non-inverting input end of the amplifier through the voltage division circuit, and the 270V DC reference signal is fed back to the inverting input end through the resistor. When the four resistance values are the same, the output voltage of the amplifier is equal to 270V direct current distortion and pulsation signals to be measured minus 270V direct current reference signals, namely distortion and pulsation signals to be measured.

The A/D converter adopts a 16-bit ADC converter AD9656 based on an oversampling technology, the sampling rate of the ADC converter is 125MSPS, and the input voltage range of the A/D converter is enabled to be +/-10V through a pre-conditioning circuit.

A method for testing distortion and pulsation signals of an airplane direct current 270V power supply system comprises the following specific steps:

step one, a high-stability direct current reference signal source outputs a 270V direct current reference signal.

And step two, subtracting the 270V direct current distortion and pulsation signals to be detected from the 270V direct current reference signal by the subtraction circuit to obtain smaller distortion and pulsation signals, wherein the voltage amplitude of the smaller distortion and pulsation signals is within the range of +/-10V.

And step three, the A/D converter performs digital-to-analog conversion on the distortion and pulsation signals obtained by the subtracter to obtain measured values of the distortion and pulsation signals.

And step four, calibrating the amplitude-frequency characteristic of the subtraction circuit by adopting standard 270V direct current distortion and pulse signals.

1) A sinusoidal signal with the amplitude of 1V is used as a standard distortion and pulsation standard signal, and the frequencies are respectively as follows: distortion signal frequency: 10Hz, 25Hz, 50Hz … … 100k Hz. The signal is superimposed on a standard dc 270V signal to form a standard 270V dc distortion and ripple signal.

2) And measuring the standard signal by using a subtraction circuit, and calculating the correction coefficient of each frequency point according to the measurement result.

3) And correcting and compensating the distortion and pulsation signal values measured in the step three according to the calculated correction coefficient.

The subtraction circuit was calibrated with a standard 270V dc distortion, ripple signal, with the results shown in the table below:

table 1: subtraction circuit calibration data table

The above detailed description is intended to illustrate the objects, aspects and advantages of the present invention, and it should be understood that the above detailed description is only exemplary of the present invention and is not intended to limit the scope of the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.