A method, system and storage medium for calculating electrical parameters of a brushless generator set

Abstract

The present invention relates to an electric parameter calculation method, system and storage medium of a brushless generator set, and the method comprises the following steps: according to the characteristic of the coaxial rotation of the permanent magnet machine and the generator, a corresponding relationship table between the permanent magnet machine frequency and the number of sampling points per cycle and the number of harmonics is established; the permanent magnet machine frequency and the generator frequency are measured; based on the corresponding relationship table, according to the ratio of the permanent magnet machine frequency to the generator frequency, the sampling period for AC sampling of the permanent magnet machine voltage is adjusted; according to the sampling period, the permanent magnet machine voltage is AC sampled to obtain the voltage sampling value of the permanent magnet machine at each sampling point of the cycle; based on the harmonic calculation formula of Fourier transform, according to the number of sampling points and the number of harmonics at the corresponding permanent magnet machine frequency in the corresponding relationship table, the permanent magnet machine voltage is calculated. The present invention is to adaptively select the number of sampling points without paying attention to the rated frequency of the permanent magnet machine, and accurately and quickly calculate the permanent magnet machine voltage according to the permanent magnet machine frequency, and has strong applicability and high reliability.

Description

Technical Field

[0001] The present invention relates to the field of motor excitation, and in particular to an electrical parameter calculation method, system and storage medium of a brushless generator set. Background Art

[0002] The generator excitation system is an independent system and one of the important systems for generator control. It has the characteristics of real-time adjustment and rapid response. The three-machine brushless generator set is more and more widely used because of its simple maintenance and high safety. The permanent magnet machine replaces the excitation transformer with a low cost. However, permanent magnet machine failures occasionally occur. At present, all excitation products do not have the function of monitoring the voltage of the permanent magnet machine. In order to improve intelligent monitoring and quickly judge faults, it is very necessary for the excitation regulation system to monitor the voltage state of the permanent magnet machine. The excitation system must be able to correctly measure the voltage of the permanent magnet machine before fault judgment can be made. The generator frequency in my country is 50Hz, but the frequency of the permanent magnet machine ranges from 50Hz to 500Hz, and it is not necessarily an integer multiple of 50Hz. Most permanent magnet machines have relatively high frequencies, and some permanent magnet machines do not even indicate the rated frequency. The permanent magnet machine is used for excitation rectification, and its voltage waveform is severely distorted, which makes it very difficult for the excitation system to measure the voltage of the permanent magnet machine. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method, system and storage medium for calculating the electrical parameters of a brushless generator set, which can accurately calculate the voltage of a permanent magnet machine and has strong applicability and high reliability.

[0004] The technical solution of the present invention to solve the above technical problem is as follows: a method for calculating the electrical parameters of a brushless generator set, the brushless generator set includes a generator and a permanent magnet machine, the electrical parameters include the permanent magnet machine voltage, and the electrical parameter calculation method includes the following steps:

[0005] According to the characteristic that the permanent magnet machine and the generator rotate coaxially, a corresponding relationship table between the permanent magnet machine frequency and the number of sampling points per cycle and the number of harmonics is established in advance;

[0006] Measuring the frequency of permanent magnet machines and generators;

[0007] Based on the correspondence table, according to the ratio of the permanent magnet machine frequency to the generator frequency, adjusting the sampling period of the AC sampling of the permanent magnet machine voltage, so that the number of sampling points of the permanent magnet machine under each cycle of AC sampling is the same as the number of sampling points under the corresponding permanent magnet machine frequency in the correspondence table;

[0008] Performing AC sampling on the voltage of the permanent magnet machine according to the sampling period to obtain a voltage sampling value of the permanent magnet machine at each sampling point of the cycle;

[0009] Based on the Fourier transform harmonic calculation formula, the permanent magnet machine voltage is calculated according to the voltage sampling value of the permanent magnet machine at each cycle sampling point and the number of sampling points and the harmonic order at the corresponding permanent magnet machine frequency in the corresponding relationship table.

[0010] Based on the above-mentioned method for calculating electrical parameters of a brushless generator set, the present invention also provides a system for calculating electrical parameters of a brushless generator set.

[0011] An electrical parameter calculation system for a brushless generator set, the brushless generator set comprising a generator and a permanent magnet machine, the electrical parameter calculation system is applied to the electrical parameter calculation method for the brushless generator set as described above, the electrical parameter comprising a permanent magnet machine voltage, the electrical parameter calculation system comprising the following modules,

[0012] A corresponding relationship table establishment module, which is used to establish in advance a corresponding relationship table between the permanent magnet machine frequency and the number of sampling points per cycle and the number of harmonics according to the characteristic that the permanent magnet machine and the generator rotate coaxially;

[0013] A frequency measurement module, which is used to measure the permanent magnet machine frequency and the generator frequency;

[0014] A sampling point number adjustment module, which is used to adjust the sampling period of AC sampling of the permanent magnet machine voltage based on the corresponding relationship table and according to the ratio of the permanent magnet machine frequency to the generator frequency, so that the number of sampling points of the permanent magnet machine under each cycle of AC sampling is the same as the number of sampling points under the corresponding permanent magnet machine frequency in the corresponding relationship table;

[0015] A permanent magnet machine voltage sampling module, which is used to perform AC sampling on the permanent magnet machine voltage according to the sampling period to obtain a voltage sampling value of the permanent magnet machine at each sampling point of the cycle;

[0016] The permanent magnet machine voltage calculation module is used to calculate the permanent magnet machine voltage based on the harmonic calculation formula of Fourier transform, according to the voltage sampling value of the permanent magnet machine at each cycle sampling point and the number of sampling points and harmonic order at the corresponding permanent magnet machine frequency in the corresponding relationship table.

[0017] Based on the above-mentioned method for calculating the electrical parameters of a brushless generator set, the present invention also provides a computer storage medium.

[0018] A computer storage medium comprises a memory and a computer program stored in the memory. When the computer program is executed, the electric parameter calculation method of the brushless generator set as described above is implemented.

[0019] The beneficial effects of the present invention are as follows: the electrical parameter calculation method, system and storage medium of the brushless generator set of the present invention utilize the coaxial rotation of the permanent magnet machine and the generator, and the generator frequency and the permanent magnet machine frequency always maintain the same ratio. Under the condition of not paying attention to the rated frequency of the permanent magnet machine, the number of sampling points is adaptively selected according to the ratio of the permanent magnet machine frequency to the generator frequency, and the permanent magnet machine voltage is accurately and quickly calculated according to the permanent magnet machine frequency, which has strong applicability and high reliability. Therefore, the present invention can monitor the permanent magnet machine voltage online with high precision, and detect in real time whether the output voltage of the permanent magnet machine is normal to make fault judgment and alarm. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A flow chart of a method for calculating electrical parameters of a brushless generator set according to the present invention;

[0021] Figure 2 It is a circuit structure diagram of a permanent magnet machine frequency measurement circuit;

[0022] Figure 3 It is a circuit structure diagram of a permanent magnet machine voltage sampling circuit;

[0023] Figure 4 It is a circuit structure diagram of a generator frequency measurement circuit;

[0024] Figure 5 It is a circuit structure diagram of a generator voltage sampling circuit;

[0025] Figure 6 The present invention is a structural block diagram of an electrical parameter calculation system for a brushless generator set. DETAILED DESCRIPTION

[0026] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0027] like Figure 1 As shown, a method for calculating electrical parameters of a brushless generator set, the brushless generator set includes a generator and a permanent magnet machine, the electrical parameters include a permanent magnet machine voltage, and the electrical parameter calculation method includes the following steps:

[0028] The electrical parameters include the permanent magnet machine voltage, and the electrical parameter calculation method includes the following steps:

[0029] According to the characteristic that the permanent magnet machine and the generator rotate coaxially, a corresponding relationship table between the permanent magnet machine frequency and the number of sampling points per cycle and the number of harmonics is established in advance;

[0030] Measuring the frequency of permanent magnet machines and generators;

[0031] Based on the correspondence table, according to the ratio of the permanent magnet machine frequency to the generator frequency, adjusting the sampling period of the AC sampling of the permanent magnet machine voltage, so that the number of sampling points of the permanent magnet machine under each cycle of AC sampling is the same as the number of sampling points under the corresponding permanent magnet machine frequency in the correspondence table;

[0032] Performing AC sampling on the voltage of the permanent magnet machine according to the sampling period to obtain a voltage sampling value of the permanent magnet machine at each sampling point of the cycle;

[0033] Based on the Fourier transform harmonic calculation formula, the permanent magnet machine voltage is calculated according to the voltage sampling value of the permanent magnet machine at each cycle sampling point and the number of sampling points and the harmonic order at the corresponding permanent magnet machine frequency in the corresponding relationship table.

[0034] In the electrical parameter calculation method of the present invention: through market research, the permanent magnet machine frequencies used by the three-machine brushless generator mainly include the frequencies shown in Table 1, and the established corresponding relationship table is specifically shown in Table 1.

[0035] Table 1: Correspondence table

[0036]

[0037]

[0038] In the electrical parameter calculation method of the present invention: the specific steps of measuring the frequency of the permanent magnet machine are:

[0039] Passing the output of the permanent magnet machine through a first voltage transformer and a first second-order low-pass filter in sequence to obtain an AC voltage signal of the permanent magnet machine;

[0040] The AC voltage signal of the permanent magnet machine is converted into a first symmetrical square wave signal with an amplitude of ±12V by using a first zero-crossing hysteresis comparison circuit;

[0041] Using a first pulse limiting circuit to convert the first square wave signal into a second symmetrical square wave signal of 0 to 3.3 V acceptable to the CPU;

[0042] The CPU is used to capture the first interval count value of two consecutive pulse rising edges of the second symmetrical square wave signal, and the permanent magnet machine frequency is calculated according to the system clock frequency of the CPU and the first interval count value; the calculation formula of the permanent magnet machine frequency is:

[0043]

[0044] Among them, f tis the permanent magnet machine frequency, F is the system clock frequency of the CPU, and t1 is the first interval count value. In this specific embodiment, the system clock frequency of the CPU is 120×10 6 MHz.

[0045] In this specific embodiment, the first zero-crossing hysteresis comparison circuit (resistor R96, resistor R110, resistor R109, resistor R118 and comparator U9D constitute the first zero-crossing hysteresis comparison circuit) and the first pulse limiting circuit (diode D8, diode D50, resistor R299, resistor R121 and inverter U59E constitute the first pulse limiting circuit) constitute a permanent magnet machine frequency measurement circuit, inverter U59E is connected to the capture pin of the CPU, and the circuit structure of the permanent magnet machine frequency measurement circuit is as follows: Figure 2 As shown (the permanent magnet machine frequency measurement circuit can detect the frequency of any phase of the permanent magnet machine).

[0046] Since the voltage sampling value of the permanent magnet machine at each cycle sampling point is attenuated after the second-order filtering, the permanent magnet machine voltage needs to be compensated to obtain the real permanent magnet machine voltage.

[0047] Furthermore, the electrical parameter calculation method further comprises the following steps:

[0048] The amplification factor of the permanent magnet machine voltage under AC sampling is calculated according to the permanent magnet machine frequency and the component parameters in the first second-order low-pass filter, and the permanent magnet machine voltage is compensated according to the amplification factor to obtain the true value of the permanent magnet machine voltage; the calculation formula of the true value of the permanent magnet machine voltage is,

[0049]

[0050] Among them, U RMS is the true value of the permanent magnet machine voltage, U is the permanent magnet machine voltage, and A is the amplification factor.

[0051] Further, AC sampling is performed on the voltage of the permanent magnet machine according to the sampling period to obtain the voltage sampling value of the permanent magnet machine at each cycle sampling point, which specifically includes the following steps:

[0052] The AC voltage signal of the permanent magnet machine is input into an AD sampling chip, and the AD sampling chip performs AC sampling on the voltage of the permanent magnet machine according to the sampling period to obtain the voltage sampling value of the permanent magnet machine at each cycle sampling point.

[0053] In this specific embodiment, the first voltage transformer and the first second-order low-pass filter form a permanent magnet machine voltage sampling circuit, and the circuit structure of the permanent magnet machine voltage sampling circuit is as follows: Figure 3As shown. There are three first voltage transformers, namely the first first voltage transformer PT7, the second first voltage transformer PT8 and the third first voltage transformer PT9, corresponding to the three phases of the permanent magnet machine; the voltage of the permanent magnet machine is generally between 80V and 350V, and the three-phase voltage of the permanent magnet machine is connected to the primary side of the three 400V / 7.07V first voltage transformers, and the connection mode is △ connection. The secondary sides of the three first voltage transformers are respectively connected in parallel with 1nF capacitors C7, C8 and C9, and then respectively connected to the input ends of the three groups of first and second order low-pass filters to suppress high-frequency signals. The three groups of first and second order low-pass filters are respectively, a first group of first and second order low-pass filters consisting of resistor R37, resistor R43, resistor R28, capacitor C31, capacitor C32, and comparator U2B, a second group of first and second order low-pass filters consisting of resistor R56, resistor R57, resistor R58, capacitor C33, capacitor C34, and comparator U2C, and a third group of first and second order low-pass filters consisting of resistor R59, resistor R60, resistor R61, capacitor C35, capacitor C36, and comparator U2D. The electrical parameters of the three groups of first and second order low-pass filters are exactly the same, among which R37=R43=36kΩ, R28=30kΩ, C31=22nF, and C32=4.7nF. The outputs of comparator U2B, comparator U2C and comparator U2D are connected to the AD sampling chip, and the outputs of comparator U2B, comparator U2C and comparator U2D are also connected to the input ends of three groups of first zero-crossing hysteresis comparison circuits in a one-to-one correspondence.

[0054] In such Figure 3 In the permanent magnet machine voltage sampling circuit shown in FIG.

[0055] The first cutoff frequency is:

[0056]

[0057] The magnification is:

[0058]

[0059] In the electric parameter calculation method of the present invention: the specific steps of measuring the generator frequency are:

[0060] Passing the secondary voltage output of the generator excitation dedicated PT through the second voltage transformer and the second second-order low-pass filter in sequence to obtain the first AC voltage signal of the generator;

[0061] The first AC voltage signal of the generator is converted into a third symmetrical square wave signal with an amplitude of ±12V by using a second zero-crossing hysteresis comparison circuit;

[0062] The third square wave signal is converted into a fourth symmetrical square wave signal of 0 to 3.3 V acceptable to the CPU by using a second pulse limiting circuit;

[0063] The CPU is used to capture the second interval count value of two consecutive pulse rising edges of the fourth symmetrical square wave signal, and the generator frequency is calculated according to the system clock frequency of the CPU and the second interval count value; the calculation formula of the generator frequency is:

[0064]

[0065] Among them, f g is the generator frequency, F is the system clock frequency of the CPU, and t2 is the second interval count value. In this specific embodiment, the system clock frequency of the CPU is 120×10 6 MHz.

[0066] In this specific embodiment, a second second-order low-pass filter (a second second-order low-pass filter composed of resistor R36, resistor R42, resistor R27, capacitor C24, capacitor C27 and operational amplifier U2A), a second zero-crossing hysteresis comparison circuit (a second zero-crossing hysteresis comparison circuit composed of resistor R95, resistor R98, resistor R108, resistor R117 and comparator U9C) and a second pulse limiting circuit (a second pulse limiting circuit composed of diode D7, diode D49, resistor R298, resistor R122 and inverter U59D) constitute a generator frequency measurement circuit, and the circuit structure of the generator frequency measurement circuit is as follows: Figure 4 As shown (the generator frequency measurement circuit can detect the frequency of any phase of the generator. However, it should be noted that the phase of the permanent magnet machine frequency detected by the permanent magnet machine frequency measurement circuit corresponds to the phase of the generator frequency detected by the generator frequency measurement circuit, that is, the generator frequency measurement circuit detects the frequency of phase A of the generator, and the permanent magnet machine frequency measurement circuit also needs to detect the frequency of phase A of the permanent magnet machine).

[0067] In the electric parameter calculation method of the present invention: the electric parameter also includes the rated frequency of the permanent magnet machine; the electric parameter calculation method also includes the following steps:

[0068] Calculating the rated frequency of the permanent magnet machine according to the rated frequency of the generator, the generator frequency and the permanent magnet machine frequency;

[0069] The calculation formula of the rated frequency of the permanent magnet machine is:

[0070]

[0071] Among them, f e is the rated frequency of the permanent magnet machine, f t is the permanent magnet machine frequency, f g is the generator frequency, f His the rated frequency of the generator. In this specific embodiment, the rated frequency of the generator is 50 Hz.

[0072] Furthermore, the electrical parameters also include generator voltage; the electrical parameter calculation method also includes the following steps:

[0073] Passing the secondary voltage output of the generator excitation dedicated PT through the second voltage transformer and the first-order low-pass filter in sequence to obtain a second AC voltage signal of the generator;

[0074] The second AC voltage signal of the generator is input into an AD sampling chip, and the AD sampling chip performs AC sampling on the generator voltage according to the sampling period to obtain a voltage sampling value of the generator at each sampling point of the cycle;

[0075] Calculating the generator voltage according to the voltage sampling values ​​of the generator at each cycle sampling point;

[0076] The sampling interval of the permanent magnet machine voltage is the same as the sampling interval of the generator voltage.

[0077] In this specific embodiment, the second voltage transformer and the first-order low-pass filter form a generator voltage sampling circuit, and the circuit structure of the generator voltage sampling circuit is as follows: Figure 5 As shown. There are three second voltage transformers, namely the first second voltage transformer PT1, the second second voltage transformer PT2 and the third third voltage transformer PT3, corresponding to the three phases of the generator; the generator voltage is taken from the secondary voltage output of the generator excitation dedicated PT, with a rated output of 100V, and is connected to the primary sides of three 200V / 7.07V second voltage transformers, respectively, in a △ connection mode, and the secondary sides of the three second voltage transformers are connected in parallel with capacitors C1, C2 and C3 for high-frequency suppression, and three groups of first-order low-pass filters (the first group of first-order low-pass filters is composed of resistor R1 and capacitor C11, the second group of first-order low-pass filters is composed of resistor R2 and capacitor C12, and the third group of first-order low-pass filters is composed of resistor R3 and capacitor C13) respectively perform first-order RC filtering on the three-phase voltage, R1 = 100kΩ, C11 = 10nF, and capacitors C11, C12 and C13 are made of NPO material capacitors.

[0078] In such Figure 5 In the generator voltage sampling circuit shown,

[0079] The second cutoff frequency is,

[0080]

[0081] In the electrical parameter calculation method of the present invention: the harmonic calculation formula based on Fourier transform (Fourier series fundamental wave discrete expression) is specifically:

[0082]

[0083] Among them, a n is the real part of the nth harmonic, b n is the imaginary part of the nth harmonic, N is the number of sampling points per cycle, k is the serial number of the sampling point, and k=0,1,2...,N-1, n is the harmonic order, and n=0,1,2...,N-1, x(k) is the voltage sampling value of the permanent magnet machine at the kth sampling point per cycle;

[0084] The formula for calculating the voltage of the permanent magnet machine is specifically:

[0085]

[0086] Wherein, U is the permanent magnet machine voltage.

[0087] In the electrical parameter calculation method of the present invention: the generator frequency is 50Hz, the AD sampling chip samples at an interval of 32 points per cycle, and at the same time, the sampling interval of the permanent magnet machine voltage is the same as the sampling interval of the generator voltage, and is sampled together with the generator voltage. Since the permanent magnet machine rotates coaxially with the generator, its frequency and the generator maintain a constant ratio. According to 50Hz sampling of 32 points per cycle and Nyquist sampling theorem, the sampling frequency needs to be greater than 2 times of the highest frequency. It can be derived that the AC voltage waveform with the highest calculated frequency of 50×32÷2=800Hz can be derived. The sampling points and the number of harmonics are adjusted according to the permanent magnet machine frequency and the generator frequency. The number of sampling points and the number of calculated harmonics at a certain frequency can always be found to calculate the permanent magnet machine voltage.

[0088] In the electrical parameter calculation method of the present invention: the sine value and cosine value of each harmonic can be stored as a table in advance, the FFT calculation function (harmonic calculation formula) corresponding to all rated frequencies in Table 1 can be stored, and the sampling point can be set to a maximum value of 96 points. Once the generator rotates, the generator frequency and the permanent magnet machine frequency can be monitored, and the sampling point can be adjusted according to the permanent magnet machine frequency ratio and the corresponding FFT function is called to calculate the voltage, and the permanent magnet machine voltage is compensated according to the permanent magnet machine frequency, so that the real permanent magnet machine voltage can be obtained. At the same time, if the specific rated frequency of the permanent magnet machine is known in advance, the rated frequency of the permanent magnet machine can be set, so that the rated frequency of the permanent magnet machine does not need to be monitored every time the machine is turned on.

[0089] According to the above measurement method, through the actual excitation system test, the specific test data is shown in Table 2.

[0090] Table 2

[0091]

[0092]

[0093] Through experimental tests and on-site unit test data results, it is concluded that the electrical parameter calculation method of the present invention has extremely high test accuracy and still meets the measurement accuracy of 0.2% at a maximum frequency of 500Hz. The electrical parameter calculation method of the present invention can fully meet the rapid measurement response of the excitation system.

[0094] Based on the above-mentioned method for calculating electrical parameters of a brushless generator set, the present invention also provides a system for calculating electrical parameters of a brushless generator set.

[0095] like Figure 6 As shown, an electrical parameter calculation system of a brushless generator set, the brushless generator set includes a generator and a permanent magnet machine, the electrical parameter calculation system is applied to the electrical parameter calculation method of the brushless generator set as described above, the electrical parameter includes the permanent magnet machine voltage, and the electrical parameter calculation system includes the following modules,

[0096] A corresponding relationship table establishment module, which is used to establish in advance a corresponding relationship table between the permanent magnet machine frequency and the number of sampling points per cycle and the number of harmonics according to the characteristic that the permanent magnet machine and the generator rotate coaxially;

[0097] A frequency measurement module, which is used to measure the permanent magnet machine frequency and the generator frequency;

[0098] A sampling point number adjustment module, which is used to adjust the sampling period of AC sampling of the permanent magnet machine voltage based on the corresponding relationship table and according to the ratio of the permanent magnet machine frequency to the generator frequency, so that the number of sampling points of the permanent magnet machine under each cycle of AC sampling is the same as the number of sampling points under the corresponding permanent magnet machine frequency in the corresponding relationship table;

[0099] A permanent magnet machine voltage sampling module, which is used to perform AC sampling on the permanent magnet machine voltage according to the sampling period to obtain a voltage sampling value of the permanent magnet machine at each sampling point of the cycle;

[0100] The permanent magnet machine voltage calculation module is used to calculate the permanent magnet machine voltage based on the harmonic calculation formula of Fourier transform, according to the voltage sampling value of the permanent magnet machine at each cycle sampling point and the number of sampling points and harmonic order at the corresponding permanent magnet machine frequency in the corresponding relationship table.

[0101] Based on the above-mentioned method for calculating the electrical parameters of a brushless generator set, the present invention also provides a computer storage medium.

[0102] A computer storage medium comprises a memory and a computer program stored in the memory. When the computer program is executed, the electric parameter calculation method of the brushless generator set as described above is implemented.

[0103] The present invention discloses an electrical parameter calculation method, system and storage medium for a brushless generator set. The permanent magnet machine and the generator rotate coaxially, and the generator frequency and the permanent magnet machine frequency always maintain the same ratio. Under the condition that the rated frequency of the permanent magnet machine is not concerned, the number of sampling points is adaptively selected according to the ratio of the permanent magnet machine frequency to the generator frequency, and the permanent magnet machine voltage is accurately and quickly calculated according to the permanent magnet machine frequency. The method has strong applicability and high reliability. Therefore, the present invention can monitor the permanent magnet machine voltage online with high precision, detect in real time whether the output voltage of the permanent magnet machine is normal, make fault judgment and give an alarm.

[0104] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calculating electrical parameters of a brushless generator set, the brushless generator set comprising a generator and a permanent magnet machine, characterized in that: The electrical parameters include the permanent magnet machine voltage, and the electrical parameter calculation method includes the following steps: According to the characteristic that the permanent magnet machine and the generator rotate coaxially, a corresponding relationship table between the permanent magnet machine frequency and the number of sampling points per cycle and the number of harmonics is established in advance; Measuring the frequency of permanent magnet machines and generators; Based on the correspondence table, according to the ratio of the permanent magnet machine frequency to the generator frequency, adjusting the sampling period of the AC sampling of the permanent magnet machine voltage, so that the number of sampling points of the permanent magnet machine under each cycle of AC sampling is the same as the number of sampling points under the corresponding permanent magnet machine frequency in the correspondence table; Performing AC sampling on the voltage of the permanent magnet machine according to the sampling period to obtain a voltage sampling value of the permanent magnet machine at each sampling point of the cycle; Based on the Fourier transform harmonic calculation formula, the permanent magnet machine voltage is calculated according to the voltage sampling value of the permanent magnet machine at each cycle sampling point and the number of sampling points and the harmonic order at the corresponding permanent magnet machine frequency in the corresponding relationship table.

2. The method for calculating electrical parameters of a brushless generator set according to claim 1, characterized in that: The specific steps to measure the frequency of a permanent magnet machine are: Passing the output of the permanent magnet machine through a first voltage transformer and a first second-order low-pass filter in sequence to obtain an AC voltage signal of the permanent magnet machine; The AC voltage signal of the permanent magnet machine is converted into a first symmetrical square wave signal with an amplitude of ±12V by using a first zero-crossing hysteresis comparison circuit; Using a first pulse limiting circuit to convert the first symmetrical square wave signal into a second symmetrical square wave signal of 0 to 3.3 V; The CPU is used to capture the first interval count value of two consecutive pulse rising edges of the second symmetrical square wave signal, and the permanent magnet machine frequency is calculated according to the system clock frequency of the CPU and the first interval count value; the calculation formula of the permanent magnet machine frequency is: Among them, f t is the permanent magnet machine frequency, F is the system clock frequency of the CPU, and t1 is the first interval count value.

3. The method for calculating electrical parameters of a brushless generator set according to claim 2, characterized in that: The electrical parameter calculation method further comprises the following steps: The amplification factor of the permanent magnet machine voltage under AC sampling is calculated according to the permanent magnet machine frequency and the component parameters in the first second-order low-pass filter, and the permanent magnet machine voltage is compensated according to the amplification factor to obtain the true value of the permanent magnet machine voltage; the calculation formula of the true value of the permanent magnet machine voltage is, Among them, U RMS is the true value of the permanent magnet machine voltage, U is the permanent magnet machine voltage, and A is the amplification factor.

4. The method for calculating electrical parameters of a brushless generator set according to claim 3, characterized in that: Performing AC sampling on the permanent magnet machine voltage according to the sampling period to obtain the voltage sampling value of the permanent magnet machine at each sampling point of the cycle specifically includes the following steps: The AC voltage signal of the permanent magnet machine is input into an AD sampling chip, and the AD sampling chip performs AC sampling on the voltage of the permanent magnet machine according to the sampling period to obtain the voltage sampling value of the permanent magnet machine at each cycle sampling point.

5. The method for calculating electrical parameters of a brushless generator set according to claim 1, characterized in that: The specific steps to measure the generator frequency are: Passing the secondary voltage output of the generator excitation dedicated PT through the second voltage transformer and the second second-order low-pass filter in sequence to obtain the first AC voltage signal of the generator; The first AC voltage signal of the generator is converted into a third symmetrical square wave signal with an amplitude of ±12V by using a second zero-crossing hysteresis comparison circuit; Using a second pulse limiting circuit to convert the third symmetrical square wave signal into a fourth symmetrical square wave signal of 0 to 3.3V; The CPU is used to capture the second interval count value of two consecutive pulse rising edges of the fourth symmetrical square wave signal, and the generator frequency is calculated according to the system clock frequency of the CPU and the second interval count value; the calculation formula of the generator frequency is: Among them, f g is the generator frequency, F is the system clock frequency of the CPU, and t2 is the second interval count value.

6. The method for calculating electrical parameters of a brushless generator set according to claim 1, characterized in that: The electrical parameters also include the rated frequency of the permanent magnet machine; the electrical parameter calculation method also includes the following steps: Calculating the rated frequency of the permanent magnet machine according to the rated frequency of the generator, the generator frequency and the permanent magnet machine frequency; The calculation formula of the rated frequency of the permanent magnet machine is: Among them, f e is the rated frequency of the permanent magnet machine, f t is the permanent magnet machine frequency, f g is the generator frequency, f H is the rated frequency of the generator.

7. The method for calculating electrical parameters of a brushless generator set according to claim 5, characterized in that: The electrical parameters also include generator voltage; the electrical parameter calculation method also includes the following steps: Passing the secondary voltage output of the generator excitation dedicated PT through the second voltage transformer and the first-order low-pass filter in sequence to obtain a second AC voltage signal of the generator; The second AC voltage signal of the generator is input into an AD sampling chip, and the AD sampling chip performs AC sampling on the generator voltage according to the sampling period to obtain a voltage sampling value of the generator at each sampling point of the cycle; Calculating the generator voltage according to the voltage sampling values ​​of the generator at each cycle sampling point; The sampling interval of the permanent magnet machine voltage is the same as the sampling interval of the generator voltage.

8. The method for calculating electrical parameters of a brushless generator set according to any one of claims 1 to 7, characterized in that: The harmonic calculation formula based on Fourier transform is as follows: Among them, a n is the real part of the nth harmonic, b n is the imaginary part of the nth harmonic, N is the number of sampling points per cycle, k is the serial number of the sampling point, and k=0,1,2...,N-1, n is the harmonic order, and n=0,1,2...,N-1, x(k) is the voltage sampling value of the permanent magnet machine at the kth sampling point per cycle; The formula for calculating the voltage of the permanent magnet machine is specifically: Wherein, U is the permanent magnet machine voltage.

9. An electrical parameter calculation system for a brushless generator set, the brushless generator set comprising a generator and a permanent magnet machine, characterized in that: The electrical parameter calculation system is applied to the electrical parameter calculation method of the brushless generator set according to any one of claims 1 to 8, wherein the electrical parameter includes the permanent magnet machine voltage, and the electrical parameter calculation system includes the following modules: A corresponding relationship table establishment module, which is used to establish in advance a corresponding relationship table between the permanent magnet machine frequency and the number of sampling points per cycle and the number of harmonics according to the characteristic that the permanent magnet machine and the generator rotate coaxially; A frequency measurement module, which is used to measure the permanent magnet machine frequency and the generator frequency; A sampling point number adjustment module, which is used to adjust the sampling period of AC sampling of the permanent magnet machine voltage based on the corresponding relationship table and according to the ratio of the permanent magnet machine frequency to the generator frequency, so that the number of sampling points of the permanent magnet machine under each cycle of AC sampling is the same as the number of sampling points under the corresponding permanent magnet machine frequency in the corresponding relationship table; A permanent magnet machine voltage sampling module, which is used to perform AC sampling on the permanent magnet machine voltage according to the sampling period to obtain a voltage sampling value of the permanent magnet machine at each sampling point of the cycle; The permanent magnet machine voltage calculation module is used to calculate the permanent magnet machine voltage based on the harmonic calculation formula of Fourier transform, according to the voltage sampling value of the permanent magnet machine at each cycle sampling point and the number of sampling points and harmonic order at the corresponding permanent magnet machine frequency in the corresponding relationship table.

10. A computer storage medium, characterized in that: It comprises a memory and a computer program stored in the memory, and when the computer program is executed, it implements the method for calculating the electrical parameters of the brushless generator set according to any one of claims 1 to 8.

Images