A generator oil level detection method based on analog quantity acquisition

Abstract

The present invention relates to the technical field of oil level detection, and more specifically to a generator oil level detection method based on analog quantity acquisition, comprising: obtaining the theoretical oil level of the generator after a preset first duration; applying excitation when the permanent magnet motor frequency fails and the wheel load signal is in a ground state; de-excitation and obtaining the end oil level of the oil level detection; obtaining the current actual oil level of the generator after the preset first duration, and determining the generator oil level status. When the generator is in an oil level warning state, the present invention promptly issues a low oil level warning, preventing damage to the generator and ensuring the execution of the flight mission.

Description

Technical Field

[0001] The present invention relates to the technical field of oil level detection, and in particular to a generator oil level detection method based on analog quantity acquisition. Background Art

[0002] In aviation power generation systems, the correct acquisition of generator oil level signals is crucial to aviation safety. Currently, most aviation power generation systems use discrete oil level detection sensors for oil level detection. The principle is to pre-install one or two sensors at different heights inside the generator. When the oil level in the generator tank falls below the lower limit (the distance from the oil level to the oil level signal installation surface), the sensor will be detected. mm, the oil level signal detector reports a switch signal, transmits the switch signal to the generator controller, and reports a low oil level alarm after a delay judgment; when the lubricating oil level in the generator tank is higher than the upper limit (the distance from the oil level to the installation surface of the oil level signal detector) 110 When the oil level signal is on, the oil level annunciator reports a switch signal, which is transmitted to the generator controller, and after a delay judgment, it reports that the oil level is normal.

[0003] A discrete oil level sensor weighs approximately 500g and has dimensions of ∅54mm x 119mm. Based on actual usage, current discrete oil level sensors suffer from large size, weight, large oil level detection errors, and a high failure rate. Specifically, the following disadvantages exist: The discrete oil level sensor's installation location and method can affect its measurement accuracy. Due to the sensor's size and weight, the discrete oil level sensor's installation location and method can affect its measurement accuracy. Due to the sensor's size and weight, the discrete oil level sensor's measurement error is greater than that of the analog oil level sensor used in this article. Furthermore, long-term operation without proper maintenance can lead to performance degradation, increasing the failure rate.

[0004] In addition to the above-mentioned defects of discrete oil level detection sensors, discrete oil level collection methods also have inherent defects, such as:

[0005] 1. Data discontinuity: Discrete acquisition methods usually measure within a specific time interval and may not be able to reflect changes in oil volume in real time, resulting in data that is not timely and accurate enough; 2. Sampling deviation: Due to the choice of sampling time points, changes in oil volume at certain critical moments may not be captured, resulting in data deviation and affecting overall analysis and decision-making; 3. Slow response speed: When a rapid response is required, discrete acquisition methods may not be able to meet the needs of real-time monitoring, especially when the oil volume changes rapidly; 4. Complex data processing: Since the collected data is discrete, additional algorithms may be required to interpolate or estimate the data, which increases the complexity and uncertainty of data processing; 5. Environmental impact: External environmental factors (such as temperature, pressure, etc.) may affect the accuracy of discrete acquisition, especially under extreme conditions; 6. Unable to capture short-term fluctuations: For some short-term oil volume fluctuations, the discrete acquisition method may completely ignore them, resulting in misjudgment of the actual situation.

[0006] Therefore, it is necessary to provide a generator oil level detection method based on analog quantity acquisition to solve the above problems. Summary of the Invention

[0007] The present invention provides a generator oil level detection method based on analog quantity acquisition to solve the existing problems.

[0008] The present invention provides a generator oil level detection method based on analog quantity acquisition, which adopts the following technical solutions, including:

[0009] The real-time oil volume of the generator during power-on self-test is used as the initial real-time oil volume, and the theoretical oil volume of the generator after a preset first period of time is obtained according to the initial real-time oil volume;

[0010] When the permanent magnet machine frequency fails and the wheel load signal is in the ground state, the generator oil level detection excitation signal is set to the excitation state;

[0011] When the generator low oil level detection delay reaches a preset first time length, the generator oil level detection excitation signal is set to a de-excitation state, and the current real-time oil level of the generator is set as the end oil level of the oil level detection;

[0012] Obtaining the current actual oil quantity of the generator after a preset first time period according to the initial real-time oil quantity and the ending oil quantity;

[0013] Obtain the oil level status of the generator based on the theoretical oil volume and the current actual oil volume.

[0014] Preferably, the expression for the theoretical oil quantity of the generator after the preset first time period is:

[0015]

[0016] Where, Indicates the theoretical oil volume of the generator after the preset first time period; Indicates the initial real-time oil volume.

[0017] Preferably, when the permanent magnet machine frequency meets the preset frequency range and remains within the frequency range for a preset second time period, the permanent magnet machine frequency is faulty; when the permanent magnet machine frequency does not meet the preset frequency range, the permanent magnet machine frequency is normal.

[0018] Preferably, the preset frequency range is less than or equal to 100 Hz, and the preset second time length is 5 seconds.

[0019] Preferably, when the aircraft is on the ground and the generator is not rotating and the oil level is stable, the wheel load signal is in the ground state.

[0020] Preferably, the difference between the final oil level of the oil level detection and the initial real-time oil level of the oil level detection is used as the current actual oil level of the generator after the preset first time period.

[0021] Preferably, the preset first duration is 30 seconds.

[0022] Preferably, the steps of obtaining the oil level status of the generator are:

[0023] When the current actual oil level is greater than or equal to the theoretical oil level, the generator is in oil level alarm state;

[0024] When the current actual oil volume is less than the theoretical oil volume, the generator is in a normal oil level state.

[0025] Preferably, the method further comprises: placing an analog oil level detection sensor for detecting the oil level in the generator parallel to the oil level.

[0026] The beneficial effects of the present invention are:

[0027] When the aircraft is on the ground and the generator is stationary, the power supply system enters a real-time control state. After the generator controller is powered on, the generator oil level detection circuit is energized for detection, thereby obtaining the generator oil level status based on the theoretical oil level of the generator after a preset first period of time and the current actual oil level. When the generator is in the oil level alarm state, a low oil level alarm is issued in time to prevent damage to the generator and ensure the execution of the flight mission. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a flow chart of an embodiment of a generator oil level detection method based on analog quantity acquisition according to the present invention;

[0030] Figure 2 Detailed flow chart of a generator oil level detection method based on analog quantity acquisition in an embodiment of the present invention;

[0031] Figure 3 Schematic diagram of a low oil level detection circuit for a generator in an embodiment of the present invention;

[0032] Figure 4 This is a graph of oil temperature signal values ​​collected after the generator low oil level detection circuit in air and oil is stimulated in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] An embodiment of a generator oil level detection method based on analog quantity acquisition of the present invention, in this embodiment, the generator oil level detection is executed in the software real-time control, when the generator controller enters the real-time control state after power-on initialization, it detects that the wheel load signal is on the ground and the permanent magnet machine frequency is less than or equal to 100Hz and lasts for 5s, it enters the generator low oil level detection, such as Figure 1 and Figure 2 As shown, this embodiment specifically includes:

[0035] S1. Obtaining a theoretical oil volume of the generator after a preset first time period;

[0036] The real-time oil volume of the generator during power-on self-test is used as the initial real-time oil volume. The theoretical oil volume of the generator after the preset first time period is obtained based on the initial real-time oil volume. In this embodiment, the preset first time period is 30 seconds. Since the growth values ​​of the sensitive resistor in air and oil are different, a corresponding relationship between the initial value of the sensitive resistor and the difference value of the sensitive resistor after 30 seconds of excitation can be established. Specifically, see the following formula (1). The growth values ​​of the sensitive resistor in oil and air are collected. After power-on, the theoretical value of the difference value of the sensitive resistor after 30 seconds of excitation can be obtained by using the sensitive resistor value collected during de-excitation. That is, the theoretical oil volume of the generator after the preset first time period is:

[0037] (1)

[0038] Where, Indicates the theoretical oil volume of the generator after the preset first time period; Indicates the initial real-time oil level; determines whether the sensitive resistor is in oil or air through the actual values ​​30s after de-excitation and 30s after excitation. When the sensitive resistor is in air, the generator controller reports a low oil level alarm through communication.

[0039] S2: Add excitation when the permanent magnet motor frequency fails and the wheel load signal is in the ground state;

[0040] If the permanent magnet generator frequency fails and the wheel load signal is in the ground state (the aircraft is on the ground and the generator is not rotating), the generator oil level detection excitation signal is set to the activated state. Specifically, when the real-time acquired permanent magnet generator frequency is less than or equal to 100Hz, the permanent magnet generator frequency under-frequency fault flag is set to fault. If the low frequency condition lasts for the preset second duration of 5.0s, the permanent magnet generator is experiencing a low frequency fault. If the permanent magnet generator frequency is greater than 100Hz, the permanent magnet generator frequency is normal. If the oil level is stable and detectable, the generator oil level detection excitation signal is set to the activated state, the initial oil level is set to the real-time acquired generator oil level, and detection begins at the preset first duration of 30.0s for the low generator oil level delay.

[0041] S3, de-energizing, and obtaining the end oil level of the oil level detection;

[0042] When the generator low fuel level detection delay reaches a preset first duration, the generator fuel level detection excitation signal is set to a de-energized state, and the generator's current real-time fuel level is set as the ending fuel level for fuel level detection. In this embodiment, the preset first duration is 30.0 seconds. When the generator low fuel level detection delay reaches the preset first duration of 30.0 seconds, the generator fuel level detection excitation signal is set to a de-energized state, and the currently detected generator's current real-time fuel level is set as the ending fuel level for fuel level detection.

[0043] S4. Obtaining the current actual oil volume of the generator after a preset first time period, and determining the oil level status of the generator;

[0044] According to the initial real-time oil volume and the final oil volume, the current actual oil volume of the generator after the preset first time period is obtained; according to the size of the theoretical oil volume and the current actual oil volume, the oil level status of the generator is obtained.

[0045] In this embodiment, the difference between the end oil level of the oil level detection and the initial real-time oil level of the oil level detection is used as the current actual oil level of the generator after the preset first time period. When the current actual oil level is greater than or equal to the theoretical oil level, it is considered that the sensitive resistor is in the air, and the generator is determined to be in the oil level alarm state; when the current actual oil level is less than the theoretical oil level, the generator is in the normal oil level state.

[0046] In this embodiment, an analog oil level detection sensor (using a thermistor) for detecting the oil level is placed parallel to the oil surface in the generator, rather than perpendicular to the oil surface, to minimize the contact time between the oil level and the sensor, facilitating accurate measurement of whether the oil level is low. After completing the low oil level detection, the generator oil level detection excitation signal is de-excited, and the generator oil level status at this time is communicated and reported.

[0047] The following is combined with Figure 3-4 This embodiment is described as follows:

[0048] The generator low oil detection circuit of this embodiment is shown in FIG. Figure 3 Specifically, the circuit includes a relay control circuit, a filter circuit, a voltage regulator circuit, and a voltage follower circuit. During normal operation, the generator controller uses the oil level detection logic to analyze whether the oil level detection conditions are met. If so, the CPLD device's I / O port outputs a level, which is then passed through the JS164245 level conversion chip and Darlington array to close the relay coil. A thermistor sampling circuit monitors the oil temperature signal in real time.

[0049] Based on the characteristic that thermistors increase in temperature differently in different media when the heat output is the same, the oil temperature difference is used to determine the medium in which the thermistor is located after 30 seconds. The difference between the de-excitation and excitation values ​​after a period of time takes into account the different growth rates of sensitive resistors after excitation at different temperatures. Therefore, at the normal operating temperature of the airborne equipment at [-20,100]°C, a large number of experiments were conducted to obtain the oil temperature signal values ​​collected after the generator low oil detection circuit was excited in air and oil and plotted into a curve (see Figure 4 ), with the horizontal axis representing time in 100ms, and the vertical axis representing the oil temperature signal collected by the circuit. The curves show that the oil temperature signal collected by the generator low-oil detection circuit in air and oil at different temperatures rises rapidly after energizing it, then levels off after 25 seconds. To account for data acquisition errors, the difference between the de-energized and energized values ​​is read after 30 seconds of energizing the circuit for a period of time.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A generator oil level detection method based on analog quantity acquisition, characterized in that: include: The real-time oil volume of the generator during power-on self-test is used as the initial real-time oil volume, and the theoretical oil volume of the generator after a preset first period of time is obtained according to the initial real-time oil volume; When the permanent magnet machine frequency fails and the wheel load signal is in the ground state, the generator oil level detection excitation signal is set to the excitation state; When the generator low oil level detection delay reaches a preset first time length, the generator oil level detection excitation signal is set to a de-excitation state, and the current real-time oil level of the generator is set as the end oil level of the oil level detection; Obtaining the current actual oil quantity of the generator after a preset first time period according to the initial real-time oil quantity and the ending oil quantity; Obtain the oil level status of the generator based on the theoretical oil volume and the current actual oil volume.

2. The generator oil level detection method based on analog quantity acquisition according to claim 1 is characterized in that: The expression of the theoretical oil quantity of the generator after the preset first time period is: Where, Indicates the theoretical oil volume of the generator after the preset first time period; Indicates the initial real-time oil volume.

3. The generator oil level detection method based on analog quantity acquisition according to claim 1, characterized in that: When the permanent magnet motor frequency meets the preset frequency range and lasts within the frequency range for a preset second time period, the permanent magnet motor frequency is faulty; when the permanent magnet motor frequency does not meet the preset frequency range, the permanent magnet motor frequency is normal.

4. The generator oil level detection method based on analog quantity acquisition according to claim 3 is characterized in that: The preset frequency range is less than or equal to 100 Hz, and the preset second time length is 5 seconds.

5. The generator oil level detection method based on analog quantity acquisition according to claim 1, characterized in that: When the aircraft is on the ground and the generator is not rotating and the oil level is stable, the wheel load signal is in the ground state.

6. The generator oil level detection method based on analog quantity acquisition according to claim 1, characterized in that: The difference between the final oil level of the oil level detection and the initial real-time oil level of the oil level detection is used as the current actual oil level of the generator after the preset first time period.

7. The generator oil level detection method based on analog quantity acquisition according to claim 1, characterized in that: The default first duration is 30 seconds.

8. The generator oil level detection method based on analog quantity acquisition according to claim 1, characterized in that: The steps to obtain the oil level status of the generator are: When the current actual oil level is greater than or equal to the theoretical oil level, the generator is in oil level alarm state; When the current actual oil volume is less than the theoretical oil volume, the generator is in a normal oil level state.

9. The generator oil level detection method based on analog quantity acquisition according to claim 1, characterized in that: Also includes: An analog oil level detection sensor for detecting the oil level is placed in the generator parallel to the oil level.

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