CN115469149A - A frequency acquisition method and device suitable for generators in aviation power supply systems - Google Patents

Abstract

The application belongs to the technical field of motor control, and particularly relates to a frequency acquisition method and device suitable for an aviation power supply system generator. The method comprises the steps of S1, carrying out frequency division on a CPLD or FPGA clock signal, and using the clock signal after frequency division to sample and filter an aviation power supply system generator to obtain a generator frequency signal; step (ii) ofS2, performing frequency division on the generator frequency signal; s3, performing pulse counting on the generator frequency signal subjected to the frequency division by two to obtain a count value freq _ data; step S4, calculating the frequency of the generator as Freq: freq = F _{sys_clk} /n ₀ /freq _ data; wherein n is ₀ To sample the clock period, F _{sys_clk} The clock frequency of the CPLD or the FPGA. The frequency detection method and the frequency detection device can detect the frequency signals of the generator in real time, effectively improve the anti-interference capacity of the frequency detection of the generator, and improve the accuracy and reliability of the frequency detection.

Description

A frequency acquisition method and device suitable for generators in aviation power supply systems

technical field

The application belongs to the technical field of motor control, and in particular relates to a frequency collection method and device suitable for generators in aviation power supply systems.

Background technique

Multi-electric and all-electric aircraft have become the general trend of modern aviation technology development. The mainstream trend of multi-electric and all-electric aircraft power systems is to adopt large-capacity variable-speed variable-frequency AC power generation technology to generate 360-800Hz variable-frequency AC power. As aviation systems have higher and higher requirements for power quality, the control requirements for generators are also becoming more and more precise. The frequency of the generator is an important parameter for the real-time control of the generator by the aviation power system. In the generator working environment, the positive and negative half waves of the generator output voltage are not symmetrical, and the generator frequency detection will also be affected by electromagnetic interference. In the process of generator control, it is required to quickly and safely protect the on-board power generation system, so how to quickly, safely and reliably detect the frequency of the generator is a technical difficulty in the aviation power system.

At present, there are two main ways to detect the generator frequency of the aviation power system. One is to capture the generator frequency signal through the ECAP module of the DSP, and obtain the generator frequency signal through the DSP clock pulse counting method; because the ECAP module of the DSP does not It has the function of filtering the generator frequency signal, but its anti-interference ability is poor, and the DSP needs to enable the interrupt function of the ECAP module. If there is a large glitch in the generator frequency signal, it may cause the DSP to respond incorrectly to the ECAP interrupt at this time, resulting in the acquired The frequency value is inaccurate. The other is that the DSP samples the generator voltage signal, then filters the voltage signal (such as the IIR algorithm), and finally performs zero-crossing detection on the filtered generator voltage signal to obtain the generator frequency; the algorithm of this method is more complicated , and requires a large amount of data calculation, it is difficult to guarantee its rapidity.

Contents of the invention

In order to solve the above problems, the first aspect of the present application provides a frequency acquisition method suitable for generators in aviation power systems, which mainly includes:

Step S1, divide the frequency of the CPLD or FPGA clock signal, and use the frequency-divided clock signal to sample and filter the generator of the aviation power system to obtain the generator frequency signal;

Step S2, performing frequency division by two on the frequency signal of the generator;

Step S3, counting the pulses of the generator frequency signal after frequency division by two to obtain the count value freq_data;

Step S4, calculate the generator frequency as Freq:

Freq = F _{sys_clk} / n ₀ / freq_data;

Among them, n ₀ is the sampling clock period, and F _{sys_clk} is the clock frequency of CPLD or FPGA.

Preferably, in step S1, the generator of the aviation power system is filtered by setting a filter window.

Preferably, in step S1, frequency division by _n0 is performed on the CPLD or FPGA clock signal, wherein _n0 takes any value from 3 to 10.

The second aspect of the application provides a frequency acquisition device suitable for generators in aviation power systems, mainly including:

The filter module is used to divide the frequency of the CPLD or FPGA clock signal, and use the frequency-divided clock signal to sample and filter the generator of the aviation power system to obtain the generator frequency signal;

a two-frequency division processing module, configured to perform two-frequency division processing on the generator frequency signal;

The pulse counting module is used to count the pulses of the generator frequency signal after frequency division by two to obtain the count value freq_data;

The generator frequency calculation module is used to calculate the generator frequency as Freq:

Freq = F _{sys_clk} / n ₀ / freq_data;

Among them, n ₀ is the sampling clock period, and F _{sys_clk} is the clock frequency of CPLD or FPGA.

Preferably, the filtering module includes a filtering window setting unit, configured to filter the generator of the aviation power system by setting the filtering window.

Preferably, the filtering module includes a frequency division parameter setting unit, which is used to divide the CPLD or FPGA clock signal by n ₀ , wherein n ₀ is any value from 3 to 10.

The application can detect the frequency signal of the generator in real time, effectively improves the anti-interference ability of the generator frequency detection, and improves the accuracy and reliability of the frequency detection.

Description of drawings

Fig. 1 is an algorithm sequence diagram of a preferred embodiment of the frequency acquisition method applicable to the generator of the aviation power system of the present application.

FIG. 2 is a diagram showing the relationship between the sampling clock and the CPLD or FPGA clock signal in the embodiment shown in FIG. 1 of the present application.

Fig. 3 is a signal filtering diagram of the embodiment shown in Fig. 1 of the present application.

Fig. 4 is a sampling diagram of FPGA frequency when the generator frequency of the embodiment shown in Fig. 1 of the present application is 1200 Hz.

detailed description

In order to make the objectives, technical solutions and advantages of the implementation of the application clearer, the technical solutions in the implementation modes of the application will be described in more detail below with reference to the drawings in the implementation modes of the application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of the present application. The embodiments described below by referring to the figures are exemplary and are intended to explain the present application, and should not be construed as limiting the present application. Based on the implementation manners in this application, all other implementation manners obtained by persons of ordinary skill in the art without creative efforts fall within the scope of protection of this application. Embodiments of the present application will be described in detail below in conjunction with the accompanying drawings.

The first aspect of the present application provides a frequency acquisition method suitable for generators in aviation power systems, as shown in Figure 1, mainly including:

Step S1, divide the frequency of the CPLD or FPGA clock signal, and use the frequency-divided clock signal to sample and filter the generator of the aviation power system to obtain the generator frequency signal;

Step S2, performing frequency division by two on the frequency signal of the generator;

Step S3, counting the pulses of the generator frequency signal after frequency division by two to obtain the count value freq_data;

Step S4, calculate the generator frequency as Freq:

Freq = F _{sys_clk} / n ₀ / freq_data;

Among them, n ₀ is the sampling clock period, and F _{sys_clk} is the clock frequency of CPLD or FPGA.

In some optional implementation manners, in step S1, the generator of the aviation power system is filtered by setting a filter window.

In some optional implementation manners, in step S1, frequency division by n0 is performed on the CPLD or FPGA clock signal, where _n0 is any value from 3 to ₁₀ .

This application proposes a frequency acquisition method suitable for generators in aviation power supply systems. The method first determines the sampling clock and filter window, and filters the frequency signal of the permanent magnet machine. As shown in Figure 2, the sampling clock is the frequency-divided clock n ₀ of the CPLD/FPGA clock signal, and the filtering window is shown in Figure 3. The size of the filtering window is n, and its value is determined according to the glitch of the frequency signal of the generator of the aviation power system For example, the value can be 400.

Afterwards, the filtered generator frequency signal is divided by two. At this time, the high/low level pulse width of the frequency signal is the period of the generator frequency signal at the current moment. Finally, the sampling clock is used to divide the frequency by two. Pulse counting is performed on the frequency signal of the generator to obtain the period value of the frequency signal of the generator at the current moment, and the current frequency of the generator is calculated by using the above formula. The algorithm can detect generator frequency signal in real time, effectively improve the anti-interference ability of generator frequency detection, and improve the accuracy and reliability of frequency detection.

Figure 4 shows a specific example. The generator frequency signal is set to 1200Hz, the FPGA clock signal is 50MHz, the sampling clock is divided by 5 of the FPGA clock signal, and the filter window is 10. The verification results at the FPGA board level are shown in the figure below As shown in 4, the generator frequency can be calculated by the formula:

Freq=50×10 ⁶ /5/8333=1200Hz;

The calculated value is the same as the set value, which further illustrates that the present application can improve the accuracy and reliability of frequency detection.

The second aspect of the present application provides a frequency acquisition device suitable for generators of aviation power supply systems corresponding to the above method, mainly including:

The filter module is used to divide the frequency of the CPLD or FPGA clock signal, and use the frequency-divided clock signal to sample and filter the generator of the aviation power system to obtain the generator frequency signal;

a two-frequency division processing module, configured to perform two-frequency division processing on the generator frequency signal;

The pulse counting module is used to count the pulses of the generator frequency signal after frequency division by two to obtain the count value freq_data;

The generator frequency calculation module is used to calculate the generator frequency as Freq:

Freq = F _{sys_clk} / n ₀ / freq_data;

Among them, n ₀ is the sampling clock period, and F _{sys_clk} is the clock frequency of CPLD or FPGA.

In some optional implementation manners, the filtering module includes a filtering window setting unit, configured to filter the generator of the aviation power system by setting the filtering window.

In some optional implementation manners, the filtering module includes a frequency division parameter setting unit, which is used to divide the frequency of the CPLD or FPGA clock signal by n ₀ , wherein n ₀ is any value from 3 to 10.

The application can detect the frequency signal of the generator in real time, effectively improves the anti-interference ability of the generator frequency detection, and improves the accuracy and reliability of the frequency detection.

Although the present application has been described in detail with general descriptions and specific implementations above, it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present application. Therefore, the modifications or improvements made on the basis of not departing from the spirit of the present application all belong to the protection scope of the present application.

Claims (6)

1. A frequency acquisition method applicable to generators of aviation power system, characterized in that, comprising: Step S1, divide the frequency of the CPLD or FPGA clock signal, and use the frequency-divided clock signal to sample and filter the generator of the aviation power system to obtain the generator frequency signal; Step S2, performing frequency division by two on the frequency signal of the generator; Step S3, counting the pulses of the generator frequency signal after frequency division by two to obtain the count value freq_data; Step S4, calculate the generator frequency as Freq: Freq = F _{sys_clk} / n ₀ / freq_data; Among them, n ₀ is the sampling clock period, and F _{sys_clk} is the clock frequency of CPLD or FPGA. 2. The frequency acquisition method suitable for generators in aviation power systems according to claim 1, characterized in that, in step S1, the generators in aviation power systems are filtered by setting a filter window. 3. the frequency acquisition method that is applicable to the generator of aviation power supply system as claimed in claim 1, it is characterized in that, in step S1, carry out n ₀ frequency division to CPLD or FPGA clock signal, wherein n ₀ value is 3～10 any value in . 4. A frequency acquisition device suitable for generators in aviation power systems, characterized in that it comprises: The filter module is used to divide the frequency of the CPLD or FPGA clock signal, and use the frequency-divided clock signal to sample and filter the generator of the aviation power system to obtain the generator frequency signal; a two-frequency division processing module, configured to perform two-frequency division processing on the generator frequency signal; The pulse counting module is used to count the pulses of the generator frequency signal after frequency division by two to obtain the count value freq_data; The generator frequency calculation module is used to calculate the generator frequency as Freq: Freq = F _{sys_clk} / n ₀ / freq_data; Among them, n ₀ is the sampling clock period, and F _{sys_clk} is the clock frequency of CPLD or FPGA. 5. The frequency acquisition device applicable to generators of aviation power supply systems as claimed in claim 4, wherein the filter module includes a filter window setting unit for filtering the generators of aviation power supply systems by setting filter windows . 6. the frequency acquisition device that is applicable to aviation power supply system generator as claimed in claim 4, is characterized in that, described filtering module comprises frequency division parameter setting unit, is used for carrying out n to ₀ frequency division to CPLD or FPGA clock signal, Where n ₀ is any value from 3 to 10.

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