Temperature real-time measurement system in the thyristor shell
Technical field
The invention belongs to the power electronic system field, specifically relate to temperature real-time measurement system in a kind of thyristor shell.
Background technology
Thyristor is since 1956 are born, always towards high voltage, big sense of current development, be divided into electricity and trigger thyristor (Electrically Triggered Thyristor, ETT), light triggered thyristor (Light-Triggered Thyristor, LTT), be widely used in fields such as HVDC, SVC, TCSC, TSC.The thyristor converter valve is the core component of system's operation, in opening process, if stand fault (surge) electric current, current-rising-rate is very big, and the increase of monocrystalline silicon expansion rate and not obvious, and inhomogeneous, therefore, can form very high current density and cause local junction temperature sharply to rise in the conducting part, finally cause thyristor to burn; In turn on process, can there be high current density temperature-rise effect and defect point intrinsic excitation effect, form the circulation heating of monocrystalline silicon self, final thyristor burns; In turn off process, owing to exist restoring current and higher electric current to turn-off di/dt, junction temperature all is far longer than normal value, easily burns thyristor; In the off-state process, there is the superpotential in leakage current and RC protection loop in thyristor, and the also same circulation that produces local thermoelectricity is burnt thyristor from heating.Therefore, the thyristor junction temperature changes with outer work condition, and each side characteristics such as converter valve series average-voltage mechanism, inside and outside superpotential, excess current, reversely restoring process of thyristor, triggering control system, protection system are all played decisive role.At present, the method of determining junction temperature mainly is to calculate (as Cauer, Foster network) or calorifics emulation by thermal impedance, but because the thermal capacitance value of materials such as silicon single crystal wafer, welding flux layer, shell, insulation spacer and heating radiator differs greatly in the pipe, therefore also differ bigger between its each actual heat transfer time constant, said method extremely difficulty is calculated accurately.Therefore, press for the measuring system that to measure real time temperature in the thyristor, yet the measurement means in this application is still blank both at home and abroad.This measuring system adopts special fiber-optical grating temperature sensor, can insert molybdenum sheet layer in the pipe, real-time multimetering Temperature Distribution, minimum to the influence of thyristor body, be not subjected to extraneous strong electromagnetic, have characteristics such as volume is extra small, reliability is high, stability is strong, the linearity is good, error is little, can satisfy the test demand of all kinds of thyristor converter valves.
Summary of the invention
In order to overcome the above-mentioned defective of prior art, the objective of the invention is to propose the interior temperature real-time measurement system of thyristor shell of advantages such as a kind of volume is little, reliability is high, good stability, the linearity is good, error is little.
For realizing goal of the invention, the present invention is achieved through the following technical solutions:
Temperature real-time measurement system in a kind of thyristor shell, described thyristor comprises the copper shell, the porcelain ring, silicon chip and molybdenum sheet, the sheathed porcelain ring in the outside of described copper shell, the inside of described copper shell is provided with silicon chip and molybdenum sheet, described wafer chuck is held between two molybdenum sheets, its improvements are: this measuring system comprises fiber-optical grating temperature sensor, described fiber-optical grating temperature sensor adopts the optical fiber of being made by quartz glass, and on this optical fiber, be etched with grating, each grating is the measurement point of this measuring system, is used to realize that many gratings measure the Temperature Distribution of thyristor molybdenum sheet layer simultaneously; The molybdenum sheet of described thyristor is provided with the fluting that is used for receiving optical fiber, the porcelain ring of described thyristor is provided with the perforate that is used to draw optical fiber, described optical fiber links to each other with (FBG) demodulator by multimode optical fiber after passing this perforate, described (FBG) demodulator is demodulated to temperature signal with the catoptrical reflection wavelength that fiber-optical grating temperature sensor transmits, thereby obtain the real-time information of temperature in the brilliant lock copper shell, the data of described (FBG) demodulator after with demodulation transfer to background computer through netting twine.
Wherein, the fluting on the described molybdenum sheet is shaped as spirality, and described optical fiber places in this fluting, and all adopts high-temperature silica gel to fix in the both sides of each grating, makes between each grating and the molybdenum sheet and leaves the gap.
Wherein, described optical fiber carries hydrogen anneal process earlier, then at the position coating polyimide of this optical fiber surface except each grating.
Wherein, the diameter of described optical fiber is 0.13-0.15mm.
Wherein, the porcelain ring center line of the center line of described perforate and thyristor is perpendicular, draw optical fiber by described perforate after, in perforate, insert high-temperature silica gel and fill out envelope.
Wherein, after described optical fiber passed perforate, the outside that is positioned at the optical fiber of thyristor outside is enclosed with soft armour and hard armour from inside to outside successively, and was disconnected to prevent optical fiber pack, described optical fiber links to each other with the (FBG) demodulator that is positioned at screened room by multimode optical fiber, and described optical fiber adopts the light joint to be connected with multimode optical fiber.
Wherein, described (FBG) demodulator comprises wideband light source, isolator, directional coupler, piezoelectric ceramics, tunable F-P wave filter, photodetector, signal processor and Ethernet interface, described wideband light source sends continuous light irradiation optical fiber, described isolator is isolated each grating reflection light, described directional coupler is guided each grating reflection light and is entered tunable F-P wave filter, when the conducting centre wavelength of tunable F-P wave filter equates with optical grating reflection reflection of light wavelength, photodetector can detect largest light intensity, convert electric signal to through photodetector, the peak value of this electric signal is corresponding to the temperature of conducting centre wavelength and measurement point; The electric signal that described signal processor reception photodetector is sent also converts the ethernet communication data to, is uploaded to background computer by Ethernet interface; Simultaneously, background computer is adjusted the frequency of the sawtooth voltage that signal processor sends by Ethernet interface, controls the transmission peak wavelength of tunable F-P wave filter by this sawtooth voltage drive pressure electroceramics.
Beneficial effect of the present invention is:
1, reliability height, the good stability of this measuring system, measurement range reaches-40~310 ℃, and possesses good linearty.
2, this measuring system adopts special Fiber Bragg Grating Temperature sensor, can realize that multiple-grid point measures Temperature Distribution simultaneously, and diameter 0.13-0.15mm is 10.76ms for 100 ℃ of step response times, and maximum error is 1.69%.
3, the fiber-optical grating temperature sensor in this measuring system places the spiral fluting on the molybdenum sheet layer of thyristor, can effectively realize the distribution measuring to molybdenum sheet layer real time temperature in managing.
4, be positioned at the (FBG) demodulator of screened room, the demodulation wavelength coverage is 1510~1590nm, sweep frequency 500Hz, and demodulation speed is fast, can be used for the demodulation of Millisecond light signal.
Description of drawings
Fig. 1 is the overall framework figure of measuring system of the present invention;
Fig. 2 is the structural representation of measuring system of the present invention;
Fig. 3 is that fiber-optical grating temperature sensor is placed on the position view on the molybdenum sheet layer;
Fig. 4 is the structural principle synoptic diagram of (FBG) demodulator;
Fig. 5 is the optical fiber grating temperature-measuring schematic diagram;
Wherein, 1-copper shell, 2-porcelain ring, 3-silicon chip, the 4-molybdenum sheet, 5-fiber-optical grating temperature sensor, 51-optical fiber, 52-grating, the 6-fluting, 7-perforate, 8-multimode optical fiber, 9-(FBG) demodulator, the 10-background computer, 11-wideband light source, 12-isolator, 13-directional coupler, the 14-piezoelectric ceramics, 15-is tunable F-P wave filter, 16-photodetector, 17-signal processor, the 18-Ethernet interface, soft armour of 19-and hard armour, 20-light joint, the 21-gate pole triggers lead-in wire.
Embodiment
Below in conjunction with accompanying drawing measuring system of the present invention is further described in detail.
The thyristor converter valve is the core component of system's operation; the thyristor junction temperature changes with outer work condition, and each side characteristics such as converter valve series average-voltage mechanism, inside and outside superpotential, excess current, reversely restoring process of thyristor, triggering control system, protection system are all played decisive role.As shown in Figure 1, measuring system of the present invention mainly is made up of the fiber-optical grating temperature sensor 5 that is arranged in thyristor, (FBG) demodulator 9 and background computer 10, and electric capacity that is connected with thyristor among the figure and resistance constitute the thyristor assembly with thyristor.Fiber-optical grating temperature sensor 5 links to each other with (FBG) demodulator 9 by multimode optical fiber 8, (FBG) demodulator 9 is demodulated to temperature signal with the catoptrical reflection wavelength that fiber-optical grating temperature sensor transmits, thereby obtain the real-time information of temperature in the brilliant lock copper shell, described (FBG) demodulator 9 transfers to background computer 10 with the data after the demodulation through the Ethernet netting twine.
1, the design of fiber-optical grating temperature sensor
Fiber-optical grating temperature sensor 5 adopts the optical fiber of being made by pure quartz glass 51, be etched with several~dozens of Bragg grating 52 along optical fiber, can realize that multiple-grid point measures Temperature Distribution simultaneously, earlier optical fiber 51 is carried hydrogen anneal process, then at this optical fiber surface coating polyimide (grid point is not coated with), fibre diameter can be 0.13-0.15mm, is good with 0.13mm.Through dynamic and static verification experimental verification, this fiber-optic grating sensor can anti-310 ℃ of high temperature, are 10.76ms for 100 ℃ of step response times, and maximum error is 1.69%, and stability is high, and the linearity is good, can satisfy the needs of temperature test in the thyristor.
Carry hydrogen anneal process and adopt prior art known in those skilled in the art:
Carry hydrogen: be optical fiber 51 to be put into cryogenic high pressure (, in pressure 6~86Mpa) hydrogen, allow hydrogen permeate go in the optical fiber, to strengthen the photosensitivity of optical fiber as temperature-30~20 ℃.
Annealing: carry behind the hydrogen that remaining hydrogen molecule has diffusion motion in the grating 52, can cause the instability of grating optical characteristics, deterioration will take place along with the prolongation of time in the performance of grating.The high annealing technology promptly is earlier optical fiber to be placed high temperature, and progressively cooling again as optical fiber being placed 330 ℃, in 4 hours, progressively reduces temperature to 0 ℃, can be used for eliminating carrying optical grating construction defective behind the hydrogen, improves the stability of grating performance.
2, have the design of fiber-optical grating temperature sensor thyristor test product
As shown in Figure 2, thyristor comprises copper shell 1, porcelain ring 2, silicon chip 3 and molybdenum sheet 4, the sheathed porcelain ring 2 in the outside of described copper shell 1,, being provided with silicon chip 3 and molybdenum sheet 4 in copper shell 1 inside, silicon chip 3 is clamped between two molybdenum sheets 4.Opening of thyristor triggered lead-in wire 21 by gate pole and realized among the figure, and gate pole triggers lead-in wire 21 and enters thyristor inside by the gate pole hole on the porcelain ring 2, passes molybdenum sheet 4 backs and links to each other with silicon chip 3.
Because fiber-optic grating sensor need be inserted on molybdenum sheet before the thyristor encapsulation, therefore needs special to porcelain ring and molybdenum sheet.Fluting 6 on the molybdenum sheet requires as shown in Figure 3, twist, groove depth 0.3mm, optical fiber 51 places helical slot, and T1-T6 is 6 place's gratings 52 of fiber-optical grating temperature sensor on the figure, measures the Temperature Distribution of molybdenum sheet layer respectively.Each grating 52 both sides of fiber-optical grating temperature sensor adopt high-temperature silica gel (adopt the GE high-temperature silica gel in this example, can heatproof 275 ℃) to fix, and make and leave certain interval between each grating 52 and the molybdenum sheet 4.The porcelain ring 2 of thyristor is provided with perforate 7, and porcelain ring 2 center lines of the center line of this perforate and thyristor are perpendicular, draw optical fiber 51 by perforate 7 after, in perforate, insert high-temperature silica gel and fill out envelope.The diameter of perforate 7 can be 2.5-3.5mm, is good with 3mm, and that section outer fiber of drawing from perforate is enclosed with soft armour and hard armour 19 from inside to outside successively, and is disconnected to prevent optical fiber pack.
After the disposable cold briquetting of thyristor test product, verify through delivery test, withstand voltage, superpotential, excess current, electric parameters such as di/dt, dv/dt all meet national standard, and it is minimum to the thyristor characteristics influence that promptly this kind inserted the test product method for making of fiber-optic grating sensor.
3, the design of signal transmission form
Grow apart from linking to each other with the (FBG) demodulator 9 that is positioned at screened room after the optical signal transmission by multimode optical fiber 8 from the optical fiber 51 that perforate 7 is drawn, optical fiber adopts light joint 20 (adopting FC light joint in this example) to be connected with multimode optical fiber.
4, the design of (FBG) demodulator
The optical fiber grating temperature-measuring principle on the optical fiber that pure quartz glass is made, utilizes the method for photoengraving to make grating (FBG) as shown in Figure 5.The continuous light that wideband light source sends incides fiber grating by Transmission Fibers, and grating reflects a narrow band light selectively, the direct transmissive of all the other broadband light.Select the central wavelength lambda of the narrow band light of reflection
BSatisfy Bragg condition (claiming that this wavelength is the Bragg wavelength), promptly
λ
B=2neffΛ (1)
In the formula (1): neff is the effective refractive index of grating; Λ is the cycle of grating.This formula shows, the narrow band light central wavelength lambda of fiber grating reflection
BChange with neff and Λ, and neff and Λ through the suitable processing of installing additional, remove stress influence with temperature and STRESS VARIATION, can show as to vary with temperature.When temperature changed, because the thermo-optic effect of optical fiber pure quartz glass, grating index neff can change; The effect owing to expand with heat and contract with cold, the cycle of grating also can change, thereby causes grating Bragg wavelength X
BVariation.With formula (1) be to the pass that the temperature differentiate can obtain variation of fiber grating reflected light center and temperature variation
Δλ
B/λ
B=(α+ξ)Δt (2)
In the formula (2): α is a thermal expansivity, α=d Λ/(Λ dt); ξ is a thermo-optical coeffecient, ξ=dneff/ (neffdt).In the temperature range (0~310 ℃) of thyristor operation, α and ξ are constant, and grating wavelength changes and temperature variation presents good linear relationship, as long as measure the change of optical grating reflection wavelength, just can obtain the variation of its environment temperature, this needs (FBG) demodulator 9.
As shown in Figure 4, (FBG) demodulator 9 comprises wideband light source 11, isolator 12, directional coupler 13, piezoelectric ceramics 14, tunable F-P wave filter 15, photodetector 16, signal processor 17 and Ethernet interface 18, wideband light source 11 sends continuous light irradiation optical fiber 51, isolator 12 is isolated the reflected light of each grating 52, directional coupler 13 each grating reflection light of guiding enter tunable F-P wave filter 15, when the conducting centre wavelength of tunable F-P wave filter equates with the reflection wavelength of grating 52, photodetector 16 can detect largest light intensity, convert electric signal to through photodetector, the peak value of this electric signal is corresponding to the temperature of conducting centre wavelength and each measurement point; The electric signal that signal processor 17 reception photodetectors are sent also converts the ethernet communication data to, is uploaded to background computer 10 by Ethernet interface 18; Simultaneously, background computer is adjusted the frequency of the sawtooth voltage that signal processor sends by Ethernet interface, controls the transmission peak wavelength of tunable F-P wave filter 15 by this sawtooth voltage drive pressure electroceramics 14.
5, the design of background computer
Background computer adopts the LabVIEW software programming to realize Real Time Observation to temperature, data analysis, and data are preserved, and history such as calls at function.
Through experimental verification, above temperature real-time measurement system in She Ji the thyristor shell, can multimetering Temperature Distribution in real time, minimum to the influence of thyristor body, be not subjected to extraneous strong electromagnetic, the fiber-optic grating sensor volume is extra small, whole measuring system has characteristics such as stability is strong, reliability is high, stability is strong, the linearity is good, error is little, its measurement range is-40~310 ℃, and maximum error is 1.68%, can satisfy the test demand of all kinds of thyristor converter valves.
Should be noted that at last: above embodiment is only in order to illustrate that technical scheme of the present invention is not intended to limit, although the present invention is had been described in detail with reference to the foregoing description, those of ordinary skill in the field are to be understood that: still can make amendment or be equal to replacement the specific embodiment of the present invention, and do not break away from any modification of spirit and scope of the invention or be equal to replacement, it all should be encompassed in the middle of the claim scope of the present invention.