CN105044634A - Permanent magnet device for magnetic resonance analysis - Google Patents
Permanent magnet device for magnetic resonance analysis Download PDFInfo
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- CN105044634A CN105044634A CN201510493004.2A CN201510493004A CN105044634A CN 105044634 A CN105044634 A CN 105044634A CN 201510493004 A CN201510493004 A CN 201510493004A CN 105044634 A CN105044634 A CN 105044634A
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- yoke
- magnetic pole
- permanent magnet
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Abstract
The invention discloses a permanent magnet device for magnetic resonance analysis. The permanent magnet device comprises a yoke, magnet pole plates, guide iron and shimming coil plates; one pair of symmetrical magnet pole plates are fixed to the yoke; the yoke encloses a closed magnet loop, and the magnet pole plates are located in the magnet loop; the shimming coil plates are fixed on the magnet pole plates through the guide iron; heating resistors are fixed onto the yoke; the heating resistors are connected with a constant temperature control power source; and the magnet pole plates are provided with temperature sensors; the permanent magnet device further comprises a PID constant temperature control system for regulating the current of the heating resistors to control the uniformity of a magnetic field; the temperature sensors are connected with the PID constant temperature control system; the shimming coil plates, a shimming power source group and an automatic shimming adjustment system are connected with the PID constant temperature control system; and the PID constant temperature control system adjusts the operating current of the heating resistors according to the compensation current of the shimming coil plates. With the permanent magnet device for magnetic resonance analysis provided by the invention adopted, the problem of deterioration of the stability of the magnetic field caused by magnet temperature variation which is further caused by heat emission increase of coils can be solved.
Description
Technical field
The present invention relates to a kind of magnetic resonance analysis permanent magnet device.
Background technology
Magnet is the critical component in all NMR system, is even called as heart; Its key technical indexes has homogeneity, stability and uniform area-wide etc.; What be used as nmr magnet at present mainly contains superconducting magnet and permanent magnet.Superconducting magnet is expensive, and permanent magnet homogeneity and stability have different.Therefore permanent magnet needs to carry out shimming adjustment, shimming regulates several means, first be magnet design, next is magnet steel technology controlling and process (comprising magnet steel particle uniformity and magnetization angle homogeneity, the homogeneity of magnet steel sintering temperature, the smooth finish on magnet steel surface), mechanical shimming (mainly adjusting the magnet steel depth of parallelism and concentricity) again, passive shimming (pasting little magnetic sheet in magnetic pole plate face) again, be finally active shimming, the shim coil set namely by applying adjustable current realizes shimming and regulates.
Active shimming technology is exactly to lead loop (shim coil) the group energising of special shape design, produce a series of small magnetic field that size changes along three-dimensional space direction with certain rule, remove the various uneven item of offsetting in former magnetic field with this serial little magnetic field, finally realize the homogenising in magnetic field.
Realize on a large scale shimming time, the electric current of required shimming is larger, electric current causes coil heating amount to strengthen after increasing, the thermal value of coil adds conference to be made the magnet outside shim coil be heated to cause temperature variation, thus cause the bad stability in magnetic field, coil heating also can cause the change of self-resistance in addition, and makes shimming effect uneven.
Summary of the invention
In order to solve the problems of the prior art, the object of the invention is to provide a kind of magnetic resonance analysis permanent magnet device, realizes to solve active shimming the problem that shimming on a large scale causes coil heating.
Based on the problems referred to above, technical scheme provided by the invention is:
Magnetic resonance analysis permanent magnet device, comprise yoke, magnetic pole plate, guide iron and shim coil plate, described yoke is fixed with the magnetic pole plate of a pair symmetry, described yoke surrounds closed magnet loop and described magnetic pole plate is positioned at described magnet loop, described shim coil plate through described guiding ferropexy in described magnetic pole plate, described yoke is fixed with heating resistor, described heating resistor is connected to thermostatic control power supply, described magnetic pole plate is provided with temperature sensor, also comprise PID thermostatic control system for regulating the homogeneity of electric current with controlling magnetic field of described heating resistor, described temperature sensor is connected with described PID thermostatic control system, shim coil plate, shim power group and automatic shimming regulating system are connected to described PID thermostatic control system, described PID thermostatic control system regulates the working current of described heating resistor according to the offset current of described shim coil plate.
Further, the temperature that in described PID thermostatic control system, the ratio of pid algorithm, integration and differentiation parameter record described magnetic pole plate surface by described temperature sensor determines parameter value, using final target setting value as function argument in control procedure, obtain ratio, integration and differentiation parameter.
Further, also comprise magnet case, described yoke, magnetic pole plate, guiding iron and shim coil plate are all placed in described magnet case.
Further, described heating resistor is other is also provided with small fan.
Compared with prior art, advantage of the present invention is:
Adopt technical scheme of the present invention, shim power group, automatic shimming regulating system and shim coil plate are connected in PID thermostatic control system, can the working current of shim coil plate be counted in the constant-temperature heating system of yoke, the converting heat produced by shim coil plate is useful part, solves and after prior art coil thermal value strengthens, magnet is heated to cause temperature variation and problem that stable magnetic field is deteriorated.
Accompanying drawing explanation
In order to be illustrated more clearly in the technical scheme of the embodiment of the present invention, below the accompanying drawing used required in describing embodiment is briefly described, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is the structural representation of magnetic resonance analysis permanent magnet device embodiment of the present invention;
Fig. 2 is the fundamental diagram of active shimming system in prior art;
Fig. 3 is principle of work schematic diagram of the present invention;
Wherein: 1, yoke; 2, magnetic pole plate; 3, iron is guided; 4, shim coil plate; 5, heating resistor; 6, magnet case; 7, small fan.
Embodiment
Below in conjunction with specific embodiment, such scheme is described further.Should be understood that these embodiments are not limited to for illustration of the present invention limit the scope of the invention.The implementation condition adopted in embodiment can do further adjustment according to the condition of concrete producer, and not marked implementation condition is generally the condition in normal experiment.
See Fig. 1, for embodiments of the invention, a kind of magnetic resonance analysis permanent magnet device is provided, it comprises yoke 1, magnetic pole plate 2, guides iron 3 and shim coil plate 4, four pieces of yokes 1 are had to surround closed magnet loop in this example, yoke 1 is fixed with the magnetic pole plate 2 of a pair symmetry, magnetic pole plate 2 is all positioned at this magnet loop, shim coil plate 4 is fixed in magnetic pole plate 2 through guiding iron 3, yoke 1 and guiding iron 3 one aspect play fixing effect, and another fermentation also can realize the effect to the closed of the magnetic line of force and homogenising; In order to realize the heating to magnetic pole plate 2, in prior art, yoke 1 is fixed with heating resistor 5, see Fig. 2, heating resistor 5 working current It is controlled by PID thermostatic control system, thermostatic control power supply is connected to heating resistor 5 through PID thermostatic control system, and shim coil plate 4 working current Is is controlled by automatic shimming regulating system and shim power group.
Active shimming is when shimming on a large scale, often need larger electric current, and the heat that larger electric current causes shim coil plate 4 to produce increases, the heat that shim coil plate 4 produces can cause magnetic pole plate 2 temperature variation through guiding iron 3 to pass to magnetic pole plate 2 and stable magnetic field is deteriorated, in order to address this problem, in this example, the working current of shim coil plate 4 is introduced in the thermostatic control system of magnetic pole plate 2, PID thermostatic control system regulates the working current of heating resistor according to the offset current of shim coil plate, the working current of minimizing heating resistor 5 can realize the heated at constant temperature to magnetic pole plate 2.
Concrete, see Fig. 3, thermostatic control power supply is connected with heating resistor and shim coil plate through PID thermostatic control system respectively with shim power group, magnetic pole plate is provided with temperature sensor, this temperature sensor is connected with PID thermostatic control system, pid control algorithm is integrated with in PID thermostatic control system, the ratio of pid algorithm, the temperature that integration and differentiation parameter records magnetic pole plate surface by temperature sensor determines parameter value, using final target setting value as function argument in control procedure, obtain ratio, integration and differentiation parameter, PID thermostatic control system is the ratio (P) based on deviation, integration (I) and differential (D) automatically adjust control device, it is a kind of self-actuated controller be most widely used, its core is pid algorithm.Its discretize formula is:
U (K) is for finally to control output quantity;
Wherein, proportion adjustment control coefrficient (K
p), basic (current) deviation e (k) of reactive system; Coefficient is large, can accelerate to regulate, and reduce error, but excessive ratio makes system stability decline, and even causes system unstable; Integral adjustment coefficient (K
i), the Accumulated deviation of reactive system
make system eliminate steady-state error, improve without margin.As long as there is error, integral adjustment just carries out, until error free; Differential adjustment factor (K
d), rate of change e (the k)-e (k-1) of reflection system deviation signal, has foresight, the trend of change of error can be predicted, produce advanced control action, before deviation is not also formed, eliminated by derivation regulating action, therefore can improve the dynamic property of system.But differential has amplification to noise, strengthen differential unfavorable to system rejection to disturbance.Integration and differentiation all can not work separately, must control to coordinate with ratio.In the present invention, the electric current of shimming is counted ratio (K
p) adjustment portion, namely count e (K), to integration (K
i) and differential (K
d) then to maintain former coefficient constant.
PID thermostatic control system regulates the working current of heating resistor to be It-Is according to the offset current Is of shim coil plate, shim current is converted into useful part, can solves and cause magnetic pole plate temperature variation after shim coil plate thermal value in shimming situation on a large scale strengthens and problem that magnetic field homogeneity is reduced.
Also comprise magnet case 6 in this example, yoke 1, magnetic pole plate 2, guiding iron 3 and shim coil plate 4 are all arranged in magnet case 6 and are hedged off from the outer world.
Also small fan 7 is provided with on the side of heating resistor 5, the even heat heating magnetic pole plate 2 produced to make heating resistor in this example.
Above-mentioned example, only for technical conceive of the present invention and feature are described, its object is to person skilled in the art can be understood content of the present invention and implement according to this, can not limit the scope of the invention with this.All equivalent transformations of doing according to Spirit Essence of the present invention or modification, all should be encompassed within protection scope of the present invention.
Claims (4)
1. magnetic resonance analysis permanent magnet device, comprise yoke (1), magnetic pole plate (2), guide iron (3) and shim coil plate (4), described yoke (1) is fixed with the magnetic pole plate (2) of a pair symmetry, described yoke (1) surrounds closed magnet loop and described magnetic pole plate (2) is positioned at described magnet loop, described shim coil plate (4) is fixed in described magnetic pole plate (2) through described guiding iron (3), described yoke (1) is fixed with heating resistor (5), described heating resistor (5) is connected to thermostatic control power supply, described magnetic pole plate (2) is provided with temperature sensor (5), also comprise PID thermostatic control system for regulating the homogeneity of electric current with controlling magnetic field of described heating resistor, described temperature sensor is connected with described PID thermostatic control system, it is characterized in that: shim coil plate (4), shim power group and automatic shimming regulating system are connected to described PID thermostatic control system, described PID thermostatic control system regulates the working current of described heating resistor (5) according to the offset current of described shim coil plate.
2. magnetic resonance analysis permanent magnet device according to claim 1, it is characterized in that: the temperature that in described PID thermostatic control system, the ratio of pid algorithm, integration and differentiation parameter record described magnetic pole plate surface by described temperature sensor determines parameter value, using final target setting value as function argument in control procedure, obtain ratio, integration and differentiation parameter.
3. magnetic resonance analysis permanent magnet device according to claim 1, it is characterized in that: also comprise magnet case (6), described yoke (1), magnetic pole plate (2), guiding iron (3) and shim coil plate (4) are all placed in described magnet case.
4. magnetic resonance analysis permanent magnet device according to claim 1, is characterized in that: described heating resistor (5) is other is also provided with small fan (7).
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| CN201510493004.2A CN105044634B (en) | 2015-08-12 | 2015-08-12 | Magnetic resonance analysis permanent magnet device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102019202001B3 (en) | 2019-02-14 | 2020-06-25 | Bruker Biospin Gmbh | MAS probe head with thermally insulated sample chamber |
| CN112068055A (en) * | 2020-08-27 | 2020-12-11 | 东南大学 | Halbach magnet for noninvasive nuclear magnetic resonance detection of blood sugar of human finger |
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| JPS6343649A (en) * | 1986-08-08 | 1988-02-24 | 株式会社日立メディコ | Nuclear magnetic resonance imaging apparatus |
| CN1168475A (en) * | 1996-06-19 | 1997-12-24 | 通用电器横河医疗系统株式会社 | Magnet assembly for MRI apparatus |
| WO2000016117A1 (en) * | 1998-09-11 | 2000-03-23 | Kruip, Marcel, Jan, Marie | Temperature control for permanent magnet system |
| CN1326552A (en) * | 1998-09-11 | 2001-12-12 | 牛津磁体技术有限公司 | Temperature control system for a permanent magnetic system |
| CN101090021A (en) * | 2006-06-12 | 2007-12-19 | 西门子（中国）有限公司 | Temp. control method for magnetic field element of permanent magnetic resonance system |
| CN101451967A (en) * | 2007-12-04 | 2009-06-10 | 西门子（中国）有限公司 | Method and apparatus for improving imaging quality of nmr imaging equipment |
| CN204903743U (en) * | 2015-08-12 | 2015-12-23 | 上海健康医学院 | Magnetism is permanent magnet device for resonance analysis |
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2015
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Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS6343649A (en) * | 1986-08-08 | 1988-02-24 | 株式会社日立メディコ | Nuclear magnetic resonance imaging apparatus |
| CN1168475A (en) * | 1996-06-19 | 1997-12-24 | 通用电器横河医疗系统株式会社 | Magnet assembly for MRI apparatus |
| WO2000016117A1 (en) * | 1998-09-11 | 2000-03-23 | Kruip, Marcel, Jan, Marie | Temperature control for permanent magnet system |
| CN1326552A (en) * | 1998-09-11 | 2001-12-12 | 牛津磁体技术有限公司 | Temperature control system for a permanent magnetic system |
| CN101090021A (en) * | 2006-06-12 | 2007-12-19 | 西门子（中国）有限公司 | Temp. control method for magnetic field element of permanent magnetic resonance system |
| CN101451967A (en) * | 2007-12-04 | 2009-06-10 | 西门子（中国）有限公司 | Method and apparatus for improving imaging quality of nmr imaging equipment |
| CN204903743U (en) * | 2015-08-12 | 2015-12-23 | 上海健康医学院 | Magnetism is permanent magnet device for resonance analysis |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102019202001B3 (en) | 2019-02-14 | 2020-06-25 | Bruker Biospin Gmbh | MAS probe head with thermally insulated sample chamber |
| US11187767B2 (en) | 2019-02-14 | 2021-11-30 | Bruker Biospin Gmbh | MAS probehead with a thermally insulated sample chamber |
| CN112068055A (en) * | 2020-08-27 | 2020-12-11 | 东南大学 | Halbach magnet for noninvasive nuclear magnetic resonance detection of blood sugar of human finger |
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| CN105044634B (en) | 2018-01-19 |
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Address after: 200093 Yingkou Road, Shanghai, No. 101, No. Applicant after: SHANGHAI UNIVERSITY OF MEDICINE & HEALTH SCIENCES Applicant after: SUZHOU NIUMAG ELECTRONIC TECHNOLOGY CO., LTD. Address before: 200093 Yingkou Road, Shanghai, No. 101, No. Applicant before: SHANGHAI UNIVERSITY OF MEDICINE & HEALTH SCIENCES Applicant before: Suzhou Niumai Electronics Co., Ltd. |
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