CN114089139B - Method and device for measuring turn-to-turn insulation PDIV (pulse-induced degradation) of variable frequency motor based on frequency domain energy - Google Patents

Abstract

The invention discloses a method and a device for measuring turn-to-turn insulation PDIV (pulse induced plasticity) of a variable frequency motor based on frequency domain energy. According to the method, pulse voltage with equal step length rising is applied to inter-turn insulation of the variable frequency motor, the pressurized electromagnetic signals are analyzed from the angle of a frequency domain, N electromagnetic signals corresponding to different frequency bands are divided according to a preset frequency band interval, N corresponding frequency domain signals are obtained through frequency spectrum analysis, the probability that the N frequency domain signals cause partial discharge is obtained according to the ratio of frequency domain energy of the N frequency domain signals corresponding to the different frequency bands to total frequency domain energy corresponding to the total frequency band, and under the condition that the probability that the frequency domain signals corresponding to a target frequency band cause partial discharge is larger than a preset probability threshold value of partial discharge, the minimum external voltage corresponding to the frequency domain signals causing partial discharge is used as the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor, and then the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor can be accurately measured.

Description

Method and device for measuring inter-turn insulation PDIV of variable frequency motor based on frequency domain energy

technical field

The invention relates to the technical field of new energy vehicles, in particular to a method and device for measuring the inter-turn insulation PDIV of a variable frequency motor based on frequency domain energy.

Background technique

At present, the insulation system of the frequency conversion motor used in new energy vehicles is mostly composed of organic materials, which is an I-type insulation structure. During its service period, there should be no discharge. If discharge occurs, it will be judged that the insulation has failed.

In the prior art, according to the relevant standards of the International Electrotechnical Commission (IEC), the insulation system of the variable frequency motor should be subjected to PDIV (Partial Discharge INceptioN Voltage) testing using repetitive pulses. Moreover, the design voltage of the insulation system of the variable frequency motor should be much lower than PDIV to ensure that the variable frequency motor does not generate discharge during actual operation and avoid accelerated aging. Therefore, it is particularly important to measure PDIV accurately.

However, most of the current measurement methods make PDIV judgments by monitoring the signal amplitude or standard deviation collected by the partial discharge signal acquisition device. The signal is highly coupled, and it is very easy to generate large errors in the PDIV test results, resulting in inaccurate PDIV test results.

Contents of the invention

The object of the present invention is to provide a method and device for measuring inter-turn insulation PDIV of a variable frequency motor based on frequency domain energy, which can achieve the purpose of improving the accuracy of the PDIV test of the insulation system of a variable frequency motor.

In the first aspect, an embodiment of the present invention provides a method for measuring the inter-turn insulation PDIV of a variable frequency motor based on frequency domain energy. Signal, wherein, N is a positive integer greater than 1, and the electromagnetic signal is an electromagnetic signal generated by applying a pulse voltage with equal step length to the inter-turn insulation of the variable frequency motor;

Spectrum analysis is performed on the electromagnetic signals of N different frequency bands, and N frequency domain signals corresponding to the electromagnetic signals of N different frequency bands are obtained;

Obtain the frequency domain energy of N frequency domain signals corresponding to different frequency bands and the total frequency domain energy corresponding to the total frequency band, respectively calculate the ratio of the frequency domain energy of N frequency domain signals corresponding to different frequency bands to the total frequency domain energy corresponding to the total frequency band, Obtain the probability of partial discharge induced by N frequency domain signals;

If it is determined that the probability of partial discharge induced by the frequency domain signal corresponding to the target frequency band is greater than the preset probability threshold of partial discharge, the minimum applied voltage corresponding to the partial discharge induced by the target frequency band is taken as the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor .

In one embodiment, performing signal processing on the electromagnetic signal to obtain electromagnetic signals of N different frequency bands in the above method includes: performing amplification and denoising processing on the electromagnetic signal, and dividing according to preset frequency band intervals to obtain N different frequency bands Electromagnetic signals: Filter and detect electromagnetic signals of N different frequency bands respectively according to different frequency bands to obtain processed electromagnetic signals of N different frequency bands.

In one embodiment, the preset frequency range in the above method is 100MHz.

In one embodiment, obtaining the frequency domain energies of the N frequency domain signals respectively corresponding to different frequency bands in the above method includes: calculating and obtaining the frequency domain energies of the N frequency domain signals respectively corresponding to different frequency bands through the following formula (1);

Among them, E _f is the frequency domain energy of the Nth frequency domain signal corresponding to the Nth frequency band, l is the start frequency of the Nth frequency band, h is the stop frequency of the Nth frequency band, and F(f) is the Nth frequency band The signal amplitude corresponding to each frequency in the frequency domain signal.

In one embodiment, in the above method, the frequency domain energies corresponding to different frequency bands of N frequency domain signals and the total frequency domain energy corresponding to the total frequency bands are obtained respectively, and the frequency domain energies corresponding to different frequency bands of N frequency domain signals are respectively calculated to account for all the total frequency domain energies. The ratio of the total frequency-domain energy corresponding to the frequency band is used to obtain the probability of partial discharge induced by N frequency-domain signals, including: summing the frequency-domain energies of N frequency-domain signals corresponding to different frequency bands to obtain the total frequency-domain energy corresponding to the total frequency band ; Calculate the probability that N frequency-domain signals cause partial discharges respectively by following formula (2);

Among them, PTi is the Ef value of the frequency band corresponding to the _i -th serial number, i represents the serial number corresponding to the N-th frequency band, and Pi is the partial discharge probability of the frequency band corresponding to the i-th serial number.

In one embodiment, in the above method, the corresponding preset partial discharge probability threshold is determined according to the accuracy rate of the initial discharge voltage covering the target frequency band, wherein the preset partial discharge probability threshold is that the target frequency band does not cause inter-turn insulation of the variable frequency motor The ratio of the frequency-domain energy corresponding to the generated partial discharge to the total frequency-domain energy corresponding to the total frequency band.

In one embodiment, the different frequency bands in the above method include a first frequency band and a second frequency band, wherein the first frequency band includes 700MHz-800MHz, and the second frequency band includes 1200MHz-1300MHz.

In one embodiment, the target frequency bands in the above method include frequency bands with center frequencies of 750 MHz and 1250 MHz respectively.

In the first aspect of the present invention, by applying a pulse voltage with equal step length to the turn-to-turn insulation of the variable frequency motor, the electromagnetic signal after the pressurization is analyzed from the perspective of the frequency domain, and it is divided into N energy corresponding to different frequency bands according to the preset frequency band. For frequency domain signals, according to the energy of the N frequency domain signals corresponding to different frequency bands accounting for the total energy of all frequency domain signals corresponding to different frequency bands, it is determined that the partial discharge probability of N frequency domain signals corresponding to different frequency bands will be greater than the preset partial discharge threshold The partial discharge voltage corresponding to the target frequency with the most concentrated energy in the frequency band is used as the initial voltage PDIV of the partial discharge, and then the PDIV of the variable frequency motor can be accurately determined.

In the second aspect, an embodiment of the present invention provides a device for measuring the inter-turn insulation PDIV of a variable frequency motor based on frequency domain energy. module, a spectrum analyzer and a data processing module; the control module is used to control the pulse power supply to apply a pulse voltage with equal step length to the inter-turn insulation of the variable frequency motor; the wide-band ultra-high frequency UHF antenna is used to obtain the The electromagnetic signal after pressurization; the signal processing module is used to perform signal processing on the electromagnetic signal to obtain electromagnetic signals of N different frequency bands, wherein, N is a positive integer greater than 1; the spectrum analyzer is used for the N different frequency bands Perform spectrum analysis on electromagnetic signals to obtain N frequency domain signals corresponding to N electromagnetic signals in different frequency bands; the data processing module is used to obtain the frequency domain energy of N frequency domain signals corresponding to different frequency bands and the total frequency domain energy corresponding to the total frequency band , respectively calculate the ratio of the frequency domain energy of N frequency domain signals corresponding to different frequency bands to the total frequency domain energy corresponding to the total frequency band, and obtain the probability of partial discharge induced by N frequency domain signals; determine the frequency domain signal corresponding to the target frequency band to induce partial discharge When the probability of is greater than the preset probability threshold of partial discharge, the minimum applied voltage corresponding to partial discharge in the target frequency band is taken as the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor.

In one embodiment, the signal processing module includes an amplifying circuit, a filter array and an envelope detection circuit connected by optical fibers; the amplifying circuit is used to amplify and denoise the electromagnetic signal; the filter array is used to amplify and denoise the electromagnetic signal; The amplified and denoised electromagnetic signals are divided according to the preset frequency band intervals to obtain electromagnetic signals of N different frequency bands, and respectively filter the electromagnetic signals of N different frequency bands; the envelope detection circuit is used to separately filter the The electromagnetic signals of the N different frequency bands are subjected to envelope detection, and the electromagnetic signals of the N different frequency bands after the envelope detection processing are obtained.

In a third aspect, an embodiment of the present invention provides an electronic device, including: a processor, a storage medium, and a bus. The storage medium stores machine-readable instructions executable by the processor. When the electronic device is running, The processor communicates with the storage medium through a bus, and the processor executes the machine-readable instructions to perform the steps of the method described in the first aspect when executed.

Compared with the prior art, this embodiment has the following beneficial effects:

(1) Strong anti-interference ability, the UHF electromagnetic sensor has good directivity, and when the partial discharge signal is obtained through the frequency domain, the 500MHz filter can be used to effectively distinguish the interference from the signal in the frequency domain, avoiding traditional detection The phenomenon that the interference signal and the discharge signal appearing on the means are highly coupled in the time domain.

(2) High detection sensitivity. The ultra-high frequency electromagnetic sensor has high sensitivity and responsiveness, and can detect partial discharge signals. The filter array, spectrum analyzer and data processing module are all connected by optical fibers, with strong anti-interference ability, stable signal transmission and electromagnetic pulse speed generated by partial discharge. It is 3×108m/s, and the detection device can respond quickly.

(3) The detection speed is fast. The ultra-high frequency electromagnetic sensor adopted has high sensitivity, and the signal transmission adopts optical fiber transmission. At the same time, the electromagnetic pulse speed generated by partial discharge is 3×108m/s, which can timely respond to whether there is partial discharge in the inter-turn insulation of the new energy vehicle frequency conversion motor, and accurately determine PDIV. .

(4) The result is accurate. At present, the existing technology is mainly to determine PDIV from the time domain. The detection signal and the interference signal cannot be effectively distinguished, and the external voltage is mostly manually adjusted. FPGA applies voltage and detects partial discharge from the perspective of frequency domain to accurately determine PDIV of new energy vehicles.

(5) The safety performance of the device is excellent. The sensors used are all non-contact detection. The control of live equipment is controlled by a single-chip microcomputer with a certain insulation distance. After the test is completed, it will be reset to zero. The equipment can run safely and stably, and personnel can operate safely.

(6) The structure of the device is simple. The detection device has a simple structure, does not involve disassembly of complex mechanical structures, and is convenient for transportation and assembly.

(7) The device is easy to operate. The invention can automatically and accurately detect after the initialization parameters are set.

(8) High versatility. The invention can not only be used for the PDIV automatic test of the turn-to-turn insulation of the new energy vehicle frequency conversion motor, but also can be applied to the detection of cable defects and the insulation test of daily-use motors, and has very high promotion value.

Description of drawings

Fig. 1 shows a schematic structural diagram of a device for measuring the inter-turn insulation PDIV of a variable frequency motor based on frequency domain energy provided by an embodiment of the present invention;

FIG. 2 shows a second structural diagram of a signal processing device provided by an embodiment of the present invention;

Fig. 3 shows a schematic flow diagram of a method for measuring the inter-turn insulation PDIV of a variable frequency motor based on frequency domain energy provided by an embodiment of the present invention;

Fig. 4 shows a schematic flow diagram II of a method for measuring inter-turn insulation PDIV of a variable frequency motor based on frequency domain energy provided by an embodiment of the present invention;

FIG. 5 shows an analysis diagram of an interference spectrum when a partial discharge occurs according to an embodiment of the present invention;

Fig. 6 shows the interference spectrum analysis diagram provided by the embodiment of the present invention when no partial discharge occurs;

Fig. 7 shows a schematic structural diagram of an electronic device provided by an embodiment of the present invention.

Detailed ways

The method for managing vehicle location for rework of the present invention will be described in more detail below in conjunction with schematic diagrams, wherein a preferred embodiment of the present invention is shown, and it should be understood that those skilled in the art can modify the present invention described here, while still realizing the advantages of the present invention Effect. Therefore, the following description should be understood as the broad knowledge of those skilled in the art, but not as a limitation of the present invention.

In the following paragraphs the invention is described more specifically by way of example with reference to the accompanying drawings. Advantages and features of the present invention will be apparent from the following description and claims. It should be noted that all the drawings are in a very simplified form and use imprecise scales, and are only used to facilitate and clearly assist the purpose of illustrating the embodiments of the present invention.

At present, safety accidents such as self-ignition and explosions occur frequently due to insulation breakdown during the operation of variable frequency motors of new energy vehicles. However, the embodiment of this application provides a device and method for measuring interturn insulation PDIV of variable frequency motors based on frequency domain energy. , can accurately measure the inter-turn insulation PDIV of the frequency conversion motor of new energy vehicles, and avoid spontaneous combustion accidents of frequency conversion motors of new energy vehicles due to insulation breakdown.

Embodiment one

As shown in Figure 1, the embodiment of the present application provides a PDIV device 100 for measuring inter-turn insulation of variable frequency motors based on frequency domain energy, including: a pulse power supply 10 electrically connected to each other, a control module 20, and a broadband UHF antenna 30 , signal processing module 40, spectrum analyzer 50 and data processing module 60;

The control module 20 is used to control the pulse power supply 10 to apply a pulse voltage with equal step length to the turn-to-turn insulation of the variable frequency motor;

The broadband ultra-high frequency UHF antenna 30 is used to obtain the electromagnetic signal after the frequency conversion motor is pressurized;

The signal processing module 40 is used to perform signal processing on the electromagnetic signal according to different frequency bands to obtain electromagnetic signals of N different frequency bands, where N is a positive integer greater than 1;

The spectrum analyzer 50 is used to perform spectrum analysis on electromagnetic signals of N different frequency bands, and obtain N frequency domain signals corresponding to the electromagnetic signals of N different frequency bands;

The data processing module 60 is used to obtain the frequency domain energy corresponding to different frequency bands of the N frequency domain signals and the total frequency domain energy corresponding to the total frequency band, respectively calculate the frequency domain energy of the N frequency domain signals corresponding to different frequency bands to account for all preset total frequency bands The ratio of the corresponding total frequency domain energies is used to obtain the probability of partial discharge induced by N frequency domain signals;

If it is determined that the probability of partial discharge induced by the frequency domain signal corresponding to the target frequency band is greater than the preset probability threshold of partial discharge, the minimum applied voltage corresponding to the partial discharge induced by the target frequency band is taken as the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor .

Optionally, the control module 20 can be an FPGA control module, which is used to control the pulse power supply 10 to increase from 0V to the target voltage according to the preset voltage step, so as to avoid inaccurate measurement results caused by high voltage increase rate.

Optionally, the broadband ultra-high frequency UHF antenna 30 is used to be placed on the inner edge of the stator 200 of the variable frequency motor, and should be kept at a suitable test distance from the variable frequency motor to avoid inaccurate test results caused by the distance as much as possible.

Optionally, the broadband ultra-high frequency UHF antenna 30 can choose a sensor with good directivity and high sensitivity response, and at the same time, optical fiber can be used to transmit electromagnetic signals, which is convenient for stable signal transmission and has strong anti-interference ability.

Optionally, the signal processing module 40 can amplify the electromagnetic signal collected by the broadband UHF, perform segmental filtering for noise filtering below 500 MHz, and transmit the signal to the spectrum analyzer after signal processing by the envelope detection circuit.

Optionally, the spectrum analyzer 50 can cooperate with the signal processing module and the data processing module in real time respectively, use optical fiber for data transmission, realize real-time detection, perform spectrum analysis on electromagnetic signals of N different frequency bands, and obtain N different frequency bands N frequency-domain signals corresponding to the electromagnetic signal.

Optionally, the data processing module 60 can use a PC or DSP to perform data processing, and perform integral processing on the above-mentioned N frequency domain signals according to corresponding frequency bands, to obtain frequency domain energy of the frequency bands corresponding to the N frequency domain signals, and then can The probability of partial discharge caused by inter-turn insulation of the variable frequency motor is obtained, and when the probability value is greater than the determination value of the data processing module 60, it is determined that partial discharge occurs. Subsequently, the processed data can also be stored in the memory, and can cooperate with the above-mentioned control module to send an effective point identification signal through the data processing module, and then trigger the control module to stop boosting and determine PDIV.

Optionally, optical fibers may be used for data transmission between the above modules, so as to improve anti-interference and stabilize data transmission.

A PDIV device for measuring the inter-turn insulation of a variable frequency motor based on frequency domain energy provided by this embodiment includes a pulse power supply, a control module, a broadband UHF antenna, a signal processing module, a spectrum analyzer and a data processing module that are electrically connected to each other; Among them, by applying a pulse voltage with equal step length to the inter-turn insulation of the variable frequency motor, the electromagnetic signal after the pressurization is analyzed from the perspective of the frequency domain, and N electromagnetic signals corresponding to different frequency bands are divided into N electromagnetic signals corresponding to different frequency bands according to the preset frequency band intervals, and The corresponding N frequency domain signals are obtained through spectrum analysis, and according to the ratio of the frequency domain energy of the N frequency domain signals corresponding to different frequency bands to the total frequency domain energy corresponding to the total frequency band, the probability of partial discharge induced by the N frequency domain signals is obtained, and determined When the probability of partial discharge induced by the frequency domain signal corresponding to the target frequency band is greater than the preset probability threshold of partial discharge, the minimum applied voltage corresponding to the partial discharge induced by the target frequency band is used as the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor, and then The initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor can be accurately measured.

Optionally, as shown in FIG. 2 , the embodiment of the present application provides a signal processing module 40, the signal processing module 40 includes an amplification circuit 41, a filter array 42, and an envelope detection circuit 43 connected to each other through optical fibers;

The amplifying circuit 41 is used for amplifying and denoising the electromagnetic signal;

The filter array 42 is used to divide the amplified and denoised electromagnetic signal according to preset frequency band intervals to obtain electromagnetic signals of N different frequency bands, and respectively filter the electromagnetic signals of the N different frequency bands;

The envelope detection circuit 43 is used to respectively perform envelope detection on the filtered electromagnetic signals of N different frequency bands to obtain N electromagnetic signals of different frequency bands after envelope detection processing.

Wherein, after the above-mentioned wide-band UHF antenna 30 detects the electromagnetic signal, the detected electromagnetic signal is amplified by the above-mentioned amplifying circuit 41, and denoising processing of noise filtering below 500 MHz, and then input into the filter array 42 in sections, and passed through The filter array 42 divides according to the preset frequency range to obtain electromagnetic signals of N different frequency bands, where N is a positive integer greater than 1, and the preset frequency range can be 100 MHz, or can be determined according to actual conditions. Wherein, the electromagnetic signals of N different frequency bands are respectively filtered according to different frequency bands, and envelope detection is performed by the envelope detection circuit 43 to obtain N electromagnetic signals of different frequency bands after signal processing.

A signal processing module 40 provided in this embodiment includes an amplifying circuit 41, a filter array 42, and an envelope detection circuit 43 connected to each other by optical fibers; by performing signal amplification and denoising processing on the detected electromagnetic signal, and according to a preset The electromagnetic signals of N different frequency bands can be obtained by dividing the frequency band interval, which can be processed by segment filtering and envelope detection respectively, so that the measurement efficiency of measuring the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor can be improved.

Embodiment two

As shown in FIG. 3 , an embodiment of the present invention provides a method for measuring the inter-turn insulation PDIV of a variable-frequency motor based on frequency-domain energy, which is applied to the PDIV device for measuring the inter-turn insulation of a variable-frequency motor based on frequency-domain energy in any of the above-mentioned embodiments. The method includes:

Step S301 , acquiring electromagnetic signals of the variable frequency motor, and performing signal processing on the electromagnetic signals to obtain N electromagnetic signals of different frequency bands.

Specifically, wherein, N is a positive integer greater than 1, and the electromagnetic signal is an electromagnetic signal generated by applying a pulse voltage with an equal step increase to the inter-turn insulation of the variable frequency motor.

Before obtaining the electromagnetic signal of the variable frequency motor, the motor stator shell of the variable frequency motor can be grounded, the neutral point of the stator winding of the motor can be disconnected, and the inter-turn insulation can be applied with a pulse voltage rising from 0V in equal steps until reaching the peak value of the pulse voltage , the voltage waveform of the pulse power supply module is controlled by FPGA, and equal-step boost control is adopted to avoid inaccurate experimental results caused by high boost rates.

The broadband UHF antenna can be placed on the inner edge of the motor stator to capture the partial discharge energy, and the electromagnetic signal is detected by the broadband UHF UHF antenna, and the electromagnetic signal is processed to obtain N electromagnetic signals of different frequency bands, wherein the N is greater than 1 positive integer of .

Specifically, after the electromagnetic signal is detected, the detected electromagnetic signal is subjected to signal amplification and denoising processing of noise filtering below 500MHz, and is divided according to the preset frequency band interval to obtain N electromagnetic signals of different frequency bands, where N is A positive integer greater than 1, the preset frequency range may be 100MHz. The electromagnetic signals of N different frequency bands are then filtered in sections through the filter array according to different frequency bands, and packet detection is performed to obtain processed electromagnetic signals of N different frequency bands.

Step S302 , performing spectrum analysis on the electromagnetic signals of N different frequency bands to obtain N frequency domain signals corresponding to the electromagnetic signals of N different frequency bands.

Specifically, a spectrum analyzer can be used to perform spectrum analysis on electromagnetic signals of N different frequency bands. For example, N frequency bands of 100 MHz signals are respectively input into the spectrum analyzer to obtain N frequency bands corresponding to N electromagnetic signals of 100 MHz. domain signal.

Step S303, obtaining the frequency domain energy of N frequency domain signals corresponding to different frequency bands and the total frequency domain energy corresponding to the total frequency band, respectively calculating the frequency domain energy corresponding to different frequency bands of N frequency domain signals to the total frequency domain energy corresponding to the total frequency band The ratio of , to get the probability of partial discharge induced by N frequency domain signals;

If it is determined that the probability of partial discharge induced by the frequency domain signal corresponding to the target frequency band is greater than the preset probability threshold of partial discharge, the minimum applied voltage corresponding to the partial discharge induced by the target frequency band is taken as the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor .

Specifically, N frequency domain signals corresponding to N different frequency bands are input into the data processing module for integral processing, and the total frequency domain energy corresponding to the total frequency band is the sum of the frequency domain energy of each different frequency band, where N can be Set to 5, 10, 20, the total frequency range can be 500MHz-2000MHz, and the preset frequency range can be 100MHz, which can be determined according to the actual situation.

Then, according to the frequency domain energies corresponding to different frequency bands of the N frequency domain signals obtained above, the ratio of the frequency domain energy corresponding to different frequency bands of the N frequency domain signals to the total frequency domain energy corresponding to the total frequency band can be calculated respectively, and N Frequency-domain signal-induced probability of partial discharge.

Specifically, the probability of partial discharge induced by the N frequency domain signals is compared with the preset probability threshold of partial discharge, and when the probability of partial discharge induced by the frequency domain signal corresponding to the target frequency band is determined to be greater than the preset probability threshold of partial discharge In the lower case, the minimum applied voltage corresponding to partial discharge induced in the target frequency band is taken as the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor.

The frequency-domain energy-based PDIV method for measuring the turn-to-turn insulation of variable-frequency motors provided in this embodiment applies pulse voltages with equal step lengths to the turn-to-turn insulation of variable-frequency motors, and analyzes the electromagnetic signals after pressurization from the perspective of the frequency domain. Divide N electromagnetic signals corresponding to different frequency bands according to the preset frequency band interval, and obtain the corresponding N frequency domain signals through spectrum analysis. According to the frequency domain energy of N frequency domain signals corresponding to different frequency bands accounts for the total frequency domain energy corresponding to the total frequency band The ratio of N frequency domain signals to obtain the probability of partial discharge induced by N frequency domain signals. If the probability of partial discharge induced by the frequency domain signal corresponding to the target frequency band is greater than the preset probability threshold of partial discharge, the minimum value corresponding to the partial discharge induced by the target frequency band The applied voltage is used as the initial discharge voltage PDIV of the inter-turn insulation of the variable-frequency motor, and then the initial discharge voltage PDIV of the inter-turn insulation of the variable-frequency motor can be accurately measured.

Further, as shown in Figure 4, the electromagnetic signal is processed to obtain electromagnetic signals of N different frequency bands, including:

Step S401, amplifying and denoising the electromagnetic signal, and dividing it according to preset frequency band intervals to obtain electromagnetic signals of N different frequency bands;

Step S402 , performing filtering and envelope detection on N electromagnetic signals of different frequency bands respectively according to different frequency bands, to obtain processed electromagnetic signals of N different frequency bands.

Wherein, the preset frequency range is 100MHz, which can be selected according to actual conditions, for example, 200MHz, 300MHz and so on.

Specifically, the partial discharge electromagnetic signal in the space can be detected by the broadband UHF antenna, and the detected electromagnetic signal is amplified through the amplification circuit. The 500MHz filter can filter out the interference caused by the high-frequency power electronic disconnection, thereby realizing denoising. Afterwards, it is passed to the filter array, and the filter array divides the received signal into 100MHz frequency band intervals to form N signals with a frequency band of 100MHz.

In this embodiment, by performing signal amplification and denoising processing on the detected electromagnetic signals, and dividing them according to preset frequency band intervals to obtain electromagnetic signals of N different frequency bands, segmental filtering and envelope detection processing can be performed respectively, so that Improve the measurement efficiency of measuring the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor.

Further, the frequency domain energies of N frequency domain signals corresponding to different frequency bands are obtained, including:

The frequency domain energies corresponding to different frequency bands of the N frequency domain signals are respectively calculated by the following formula (1);

Among them, E _f is the frequency domain energy of the Nth frequency domain signal corresponding to the Nth frequency band, l is the start frequency of the Nth preset frequency band, h is the stop frequency of the Nth preset frequency band, F(f) is the amplitude of the signal at each frequency.

Specifically, the signal is divided into N frequency bands of 100MHz signals, and their corresponding frequency domain signals are respectively obtained through a spectrum analyzer. The frequency band intervals of the N frequency bands are all 100MHz, and E _f is the corresponding The frequency domain energy of the Nth frequency band, l is the start frequency of the Nth frequency band, h is the stop frequency of the Nth frequency band, and F(f) is the frequency corresponding to each frequency in the Nth frequency domain signal signal amplitude.

In this embodiment, the frequency-domain energies of the N frequency-domain signals corresponding to different frequency bands are respectively calculated through the above formula (1), so that the accuracy of measuring the initial discharge voltage PDIV of the inter-turn insulation of the variable-frequency motor can be improved.

Further, the frequency domain energy corresponding to different frequency bands of the N frequency domain signals and the total frequency domain energy corresponding to the total frequency band are obtained, and the frequency domain energy corresponding to different frequency bands of the N frequency domain signals is respectively calculated to account for the total frequency domain energy corresponding to all the total frequency bands The ratio of energy to obtain the probability of partial discharge induced by N frequency domain signals, including:

Summing the frequency-domain energies of the N frequency-domain signals corresponding to different frequency bands respectively, to obtain the total frequency-domain energy corresponding to the total frequency band;

The probability of partial discharge induced by N frequency domain signals is calculated by the following formula (2);

Wherein, PTi is the Ef value of the frequency band corresponding to the _i -th serial number, i represents the serial number corresponding to the N-th frequency band, and the Pi is the partial discharge probability of the frequency band corresponding to the i-th serial number.

Specifically, it is possible to define the ratio of the frequency-domain energy of each frequency band to the total frequency-domain energy of the total frequency band as the probability of partial discharge discharge, that is, when the ratio exceeds the preset judgment value of the data processing module, it is determined that the variable frequency motor turns Partial discharge occurs in the inter-insulation, and then the partial discharge inception voltage can be determined. The E _f value of the frequency band defined in the above formula (2) is PT, the number of frequency bands is N, and the partial discharge probability is P.

In this embodiment, by obtaining the frequency domain energies of N frequency domain signals corresponding to different frequency bands and the total frequency domain energy corresponding to the total frequency bands, the frequency domain energies of N frequency domain signals corresponding to different frequency bands are respectively calculated by the above formula (2). The ratio of the total frequency domain energy corresponding to the total frequency band obtains the probability of partial discharge induced by the N frequency domain signals, so that the partial discharge probability of the inter-turn insulation of the variable frequency motor can be accurately judged.

Further, the above method further includes: determining a corresponding preset probability threshold of partial discharge according to the accuracy of the initial discharge voltage covering the target frequency band.

Wherein, the preset partial discharge probability threshold is the ratio of the corresponding frequency domain energy to the total frequency domain energy corresponding to the total frequency band when the target frequency band does not cause the partial discharge generated by the inter-turn insulation of the variable frequency motor.

Specifically, in order to improve the accuracy of judging the partial discharge probability of the inter-turn insulation of the variable frequency motor, the corresponding preset partial discharge probability threshold can be determined according to the priority of determining the coverage target frequency band of the initial discharge voltage, for example, assuming that the preset partial discharge The probability threshold of discharge can be 5%, 10%, or 20%. If 5% is used as the probability threshold of partial discharge, the accuracy rate of covering the target frequency band can reach 90%. That is, as the threshold is set higher and higher, The higher the accuracy rate of covering the target frequency band that can determine the initial discharge voltage is.

In this embodiment, the corresponding preset partial discharge probability threshold is determined according to the accuracy rate of the initial discharge voltage covering the target frequency band, so that the probability of the partial discharge threshold can be adjusted according to the actual situation, and then the inter-turn ratio of the variable frequency motor can be accurately measured. Insulation initiation discharge voltage PDIV.

Further, the different frequency bands include a first frequency band and a second frequency band, wherein the first frequency band includes 700MHz-800MHz, and the second frequency band includes 1200MHz-1300MHz.

Specifically, the energy in the frequency domain of different frequency bands is different. After a large number of experiments, it is found that partial discharges are easily induced in the frequency bands of 700MHz-800MHz and 1200MHz-1300MHz.

Further, the target frequency includes frequency bands with center frequencies of 750 MHz and 1250 MHz respectively.

Specifically, the third-generation wide-bandgap power semiconductor devices represented by silicon carbide (SiC) and gallium nitride (GaN) are gradually replacing traditional silicon (Si)-based devices. Standards such as IEC61934 and IEC60034-27-5 clarify power Most of the electronic high-frequency interference (pulse power interference) is distributed below 500MHz. The UHF antenna in this device is used to capture and analyze the partial discharge signal. According to the experimental results, it is found that under different pulse parameters, the discharge frequency domain energy is mainly concentrated at 750MHz and Around 1250MHz.

As shown in Figure 5 and Figure 6, it can be found that the frequency domain energy of partial discharge is mainly concentrated around 750MHz and 1250MHz, and the highest amplitude is the base station signal of the mobile phone at 0.9GHz. As shown in Figure 5, there is almost no frequency-domain energy distribution in the range of 0.5GHz-2.0GHz (except mobile phone base station signals) when no partial discharge occurs, and the ratio of energy near 0.75GHz and 1.25GHz to the total energy in the frequency domain is extremely small. As shown in Figure 6, and the ratio is hardly affected by human interference (false touch, shaking, etc.), so by monitoring the magnitude of the ratio, a reasonable threshold can be set to accurately measure PDIV.

In this embodiment, through a large number of experiments, the inventor analyzed the data of each experiment, and finally found that the partial discharge frequency domain energy is mainly concentrated around 750MHz and 1250MHz, and then can be detected by the conditions of these two frequency bands, and the partial discharge can be reasonably set The threshold value makes it possible to accurately measure the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor.

Aiming at the measurement scenario of inter-turn insulation PDIV of variable frequency motors for new energy vehicles, a method for measuring inter-turn insulation PDIV of variable frequency motors based on frequency domain energy is provided. The specific process is as follows:

(S1) Disconnect the neutral point of the variable frequency motor, ground the shell, and apply a pulse voltage (peak-to-peak value) rising from 0V to the inter-turn insulation of the variable frequency motor;

(S2) Input detection parameters: sampling rate, pulse voltage rising rate, data processing module judgment value;

(S3) The test starts, the single-chip microcomputer is initialized, and the FPGA controls the pulse power supply to carry out equal-step boosting;

(S4) The broadband UHF antenna detects the electromagnetic signal, amplifies the detected electromagnetic signal, filters the noise, and then passes it into the filter array, and the filter array divides the received signal into 100MHz frequency bands to form N frequency bands of 100MHz signal of;

(S5) inputting N frequency bands as 100MHz signals into the spectrum analyzer to obtain frequency domain signals;

(S6) Input the frequency domain signal into the data processing module for integral processing to obtain the frequency domain energy of different frequency bands, use the energy of different frequency domain frequency bands to calculate the probability of partial discharge, and determine the occurrence of partial discharge when the probability is greater than the judgment value of the data processing module .

(S7) The frequency domain energy calculation method of the 100MHz frequency band is as follows:

(S7.1) The signal is divided into N frequency bands that are 100MHz signals, and its frequency domain signal is obtained through a spectrum analyzer. At this time, the frequency band interval of each frequency domain signal is 100MHz, and the amplitude of the signal under each frequency is Ff, the frequency domain energy integral value Ef is introduced, the frequency domain energy calculation formula of the frequency band is as follows:

(S8) The calculation method of partial discharge occurrence probability is as follows:

(S8.1) According to (S7.1), define the probability that the frequency domain energy of each frequency band accounts for the total frequency domain energy of the total frequency band as the probability of partial discharge release. When the probability value exceeds the data processing module judgment value, judge Partial discharge occurs, determine the inception voltage of the partial discharge. Among them, the frequency domain energy of the frequency band is PT, the number of frequency bands is N, and the partial discharge probability is P. Then, the partial discharge probability calculation formula obtained by using the frequency domain energy of each frequency band is as follows:

Among them, after a large number of experiments, it is found that the frequency domain energy integral value of 700MHz-800MHz and 1200MHz-1300MHz frequency bands is the main comparison object, that is, when the probability of partial discharge occurrence calculated under the above two frequency bands is greater than the judgment value of the data processing module, it is determined that the local A discharge occurs and the partial discharge inception voltage can then be determined.

In this embodiment, by applying a pulse voltage with equal step length to the turn-to-turn insulation of the variable frequency motor, the electromagnetic signal after the pressurization is analyzed from the perspective of the frequency domain, and N electromagnetic signals corresponding to different frequency bands are divided into N electromagnetic signals corresponding to different frequency bands according to the preset frequency range. And the corresponding N frequency domain signals are obtained through spectrum analysis, and according to the ratio of the frequency domain energy corresponding to different frequency bands of the N frequency domain signals to the total frequency domain energy corresponding to the total frequency band, the probability of partial discharge induced by the N frequency domain signals is obtained, When it is determined that the probability of partial discharge induced by the frequency domain signal corresponding to the target frequency band is greater than the preset probability threshold of partial discharge, the minimum applied voltage corresponding to the partial discharge induced by the target frequency band is used as the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor, Furthermore, the initial discharge voltage PDIV of the inter-turn insulation of the variable frequency motor can be accurately measured.

It should be understood that the above-described embodiments are only illustrative, and the circuits and methods disclosed in the embodiments of the present invention may also be implemented in other ways. For example, the division of the modules is only a logical function division, and there may be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored. or not. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be through some communication interfaces, and the indirect coupling or communication connection of devices or modules may be in electrical, mechanical or other forms. In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.

If the functions are realized in the form of software function units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium executable by a processor. Based on this understanding, the essence of the technical solution of the present invention or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to enable the processor to implement all or part of the steps of the methods described in various embodiments of the present invention when executed.

That is, those skilled in the art should understand that the embodiments of the present invention can be implemented in any form of a complete hardware embodiment, a complete software embodiment, or a combination of software and hardware.

Optionally, the embodiment of the present invention further provides an electronic device, and the electronic device may be a server, a computer, etc., and FIG. 7 shows a schematic structural diagram of the electronic device provided by the embodiment of the present invention. As shown in FIG. 7, the electronic device may include: a processor 701, a storage medium 702, and a bus 703. The storage medium 702 stores machine-readable instructions executable by the processor 701. When the electronic device is running, the processor 701 and the storage The medium 702 communicates through the bus 703 , and the processor 701 executes machine-readable instructions to execute the steps of the method for measuring the inter-turn insulation PDIV of a variable-frequency motor based on frequency-domain energy as described in the foregoing embodiments. The specific implementation manner and technical effect are similar and will not be repeated here.

For ease of illustration, only one processor is described in the above electronic device. However, it should be noted that in some embodiments, the electronic device in the present invention may also include multiple processors, so the steps performed by one processor described in the present invention may also be performed jointly or independently by multiple processors. For example, if the processor of the electronic device executes step A and step B, it should be understood that step A and step B may also be executed jointly by two different processors or independently executed in one processor. For example, the first processor performs step A, and the second processor performs step B, or the first processor and the second processor jointly perform steps A and B, and so on.

In some embodiments, a processor may include one or more processing cores (eg, a single-core processor(S) or a multi-core processor(s)). For example only, the processor may include a central processing unit (Central Processing Unit, CPU), an application specific integrated circuit (Application Specific Integrated Circuit, ASIC), an application specific instruction set processor (Application Specific Instruction-set Processor, ASIP), a graphics processing unit (Graphics Processing Unit, GPU), Physical Processing Unit (Physics Processing Unit, PPU), Digital Signal Processor (Digital Signal Processor, DSP), Field Programmable Gate Array (Field Programmable Gate Array, FPGA), Programmable Logic Device (Programmable Logic Device, PLD), controller, microcontroller unit, reduced instruction set computer (Reduced Instruction Set Computing, RISC), or microprocessor, etc., or any combination thereof.

Based on this, the embodiment of the present invention also provides a program product, which can be a storage medium such as a U disk, a mobile hard disk, ROM, RAM, a magnetic disk or an optical disk, and a computer program can be stored on the storage medium, and the computer program is processed The steps of the motor stator insulation defect detection device as described in the foregoing method embodiments are executed when the generator is running. The specific implementation manner and technical effect are similar and will not be repeated here.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field can easily think of changes or replacements within the technical scope disclosed in the present invention, and should be included in the scope of the present invention. within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Thus, provided that these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims (10)

1. A method for measuring turn-to-turn insulation PDIV of a variable frequency motor based on frequency domain energy is characterized by comprising the following steps:

acquiring electromagnetic signals of the variable frequency motor, and performing signal processing on the electromagnetic signals to obtain N electromagnetic signals of different frequency bands, wherein N is a positive integer greater than 1, and the electromagnetic signals are generated by applying pulse voltage with equal step length rising to turn-to-turn insulation of the variable frequency motor;

performing spectrum analysis on the electromagnetic signals of the N different frequency bands to obtain N frequency domain signals corresponding to the electromagnetic signals of the N different frequency bands;

acquiring frequency domain energy of the N frequency domain signals corresponding to different frequency bands and total frequency domain energy corresponding to a total frequency band, and calculating the ratio of the frequency domain energy of the N frequency domain signals corresponding to the different frequency bands to the total frequency domain energy corresponding to the total frequency band to obtain the probability of partial discharge caused by the N frequency domain signals;

and if the probability that the frequency domain signal corresponding to the target frequency band induces the partial discharge is larger than the preset probability threshold of the partial discharge, taking the minimum external voltage corresponding to the partial discharge induced by the target frequency band as the initial discharge voltage PDIV of turn-to-turn insulation of the variable frequency motor.

2. The method of claim 1, wherein the signal processing the electromagnetic signal to obtain N electromagnetic signals of different frequency bands comprises:

amplifying and denoising the electromagnetic signals, and dividing the electromagnetic signals according to a preset frequency band interval to obtain N electromagnetic signals with different frequency bands;

and respectively filtering and carrying out package detection on the N electromagnetic signals with different frequency bands according to different frequency bands to obtain the processed N electromagnetic signals with different frequency bands.

3. The method of claim 2, wherein the predetermined frequency band interval is 100MHz.

4. The method according to any one of claims 1 to 3, wherein the obtaining frequency domain energies of the N frequency domain signals corresponding to different frequency bands respectively comprises:

respectively calculating to obtain frequency domain energy of the N frequency domain signals corresponding to different frequency bands through the following formula (1);

wherein E is _f The frequency domain energy of the nth frequency domain signal corresponding to the nth frequency domain, l is the starting frequency of the nth frequency domain, h is the ending frequency of the nth frequency domain, and F (F) is the signal amplitude corresponding to each frequency in the nth frequency domain signal.

5. The method according to claim 4, wherein the obtaining frequency domain energy of the N frequency domain signals corresponding to different frequency bands and total frequency domain energy corresponding to a total frequency band respectively, and calculating a ratio of the frequency domain energy of the N frequency domain signals corresponding to different frequency bands to the total frequency domain energy corresponding to all the total frequency bands respectively to obtain the probability of the N frequency domain signals causing partial discharge comprises:

summing the frequency domain energy of the N frequency domain signals corresponding to different frequency bands respectively to obtain total frequency domain energy corresponding to the total frequency band;

respectively calculating the probability of the partial discharge caused by the N frequency domain signals through the following formula (2);

wherein PTi is E of the frequency band corresponding to the ith sequence number _f And the value i represents the serial number corresponding to the Nth frequency band, and Pi is the partial discharge probability of the frequency band corresponding to the ith serial number.

6. The method of claim 5, further comprising:

and determining a corresponding preset partial discharge probability threshold according to the accurate rate of the initial discharge voltage covering a target frequency band, wherein the preset partial discharge probability threshold is the ratio of frequency domain energy corresponding to the target frequency band without causing partial discharge generated by turn-to-turn insulation of the variable frequency motor to total frequency domain energy corresponding to a total frequency band.

7. The method of claim 6, wherein the different frequency bands comprise a first frequency band and a second frequency band, wherein the first frequency band comprises 700MHz-800MHz and the second frequency band comprises 1200MHz-1300MHz.

8. The method of claim 7, wherein the target frequency band comprises frequency bands centered at 750MHz and 1250MHz, respectively.

9. An apparatus for measuring turn-to-turn insulation PDIV of a variable frequency motor based on frequency domain energy, the apparatus comprising: the system comprises a pulse power supply, a control module, a broadband ultrahigh frequency (UHF) antenna, a signal processing module, a spectrum analyzer and a data processing module which are electrically connected with each other;

the control module is used for controlling the pulse power supply to apply pulse voltage which rises in equal step length to turn-to-turn insulation of the variable frequency motor;

the broadband ultrahigh frequency UHF antenna is used for acquiring an electromagnetic signal after the frequency conversion motor is pressurized;

the signal processing module is used for carrying out signal processing on the electromagnetic signals to obtain N electromagnetic signals with different frequency bands, wherein N is a positive integer greater than 1;

the spectrum analyzer is used for performing spectrum analysis on the electromagnetic signals of the N different frequency bands to obtain N frequency domain signals corresponding to the electromagnetic signals of the N different frequency bands;

the data processing module is used for acquiring frequency domain energy of the N frequency domain signals corresponding to different frequency bands and total frequency domain energy corresponding to a total frequency band, and calculating the ratio of the frequency domain energy of the N frequency domain signals corresponding to the different frequency bands to the total frequency domain energy corresponding to the total frequency band to obtain the probability of partial discharge caused by the N frequency domain signals;

and under the condition that the probability that the frequency domain signal corresponding to the target frequency band induces the partial discharge is larger than the preset probability threshold of the partial discharge, taking the minimum external voltage corresponding to the partial discharge induced by the target frequency band as the initial discharge voltage PDIV of turn-to-turn insulation of the variable frequency motor.

10. An electronic device, comprising: a processor, a storage medium and a bus, the storage medium storing machine-readable instructions executable by the processor, the processor and the storage medium communicating via the bus when the electronic device is operating, the processor executing the machine-readable instructions to perform the method of claim 8.

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