CN1989899A - Magnetic body thermostatic control device and method for permanent-magnet magnetic resonance imaging systems - Google Patents
Magnetic body thermostatic control device and method for permanent-magnet magnetic resonance imaging systems Download PDFInfo
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- CN1989899A CN1989899A CN 200510136752 CN200510136752A CN1989899A CN 1989899 A CN1989899 A CN 1989899A CN 200510136752 CN200510136752 CN 200510136752 CN 200510136752 A CN200510136752 A CN 200510136752A CN 1989899 A CN1989899 A CN 1989899A
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- 238000002595 magnetic resonance imaging Methods 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims description 51
- 238000010438 heat treatment Methods 0.000 claims description 46
- 230000008569 process Effects 0.000 claims description 27
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 8
- 239000000741 silica gel Substances 0.000 claims description 8
- 229910002027 silica gel Inorganic materials 0.000 claims description 8
- 238000005259 measurement Methods 0.000 claims description 7
- 230000010354 integration Effects 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 229910052697 platinum Inorganic materials 0.000 claims description 4
- 239000012774 insulation material Substances 0.000 claims description 3
- 230000001105 regulatory effect Effects 0.000 abstract description 5
- 230000005389 magnetism Effects 0.000 abstract 1
- 238000005516 engineering process Methods 0.000 description 3
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000005672 electromagnetic field Effects 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
- 229910001172 neodymium magnet Inorganic materials 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 101000629937 Homo sapiens Translocon-associated protein subunit alpha Proteins 0.000 description 1
- 238000005481 NMR spectroscopy Methods 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 102100026231 Translocon-associated protein subunit alpha Human genes 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 230000008859 change Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000002059 diagnostic imaging Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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Abstract
The invention discloses a permanent magnetism magnetic resonance imaging system magnet thermostatic control device. It includes alternating current temperature control circuit, the signal input end of temperature controller is linked with temperature sensor, and the regulating output end of temperature controller is linked into the alternating current power supply circuit of alternating current heater through the alternating current performer; and includes the direct current temperature control circuit consists of temperature sensor, temperature controller, direct current source and direct current heater. Among them, said regulating output end of temperature controller is linked into the direct current power supply circuit of direct current heater through the direct current performer, the alarm output end of temperature controller is linked into the alternating current power supply circuit of alternating current heater through the alternating current performer; the signal output end of temperature sensor, direct current heater and the power receiving terminal of alternating current heater are equipped with filter respectively; said temperature controller stores temperature control programs. The invention improves the thermal stability of permanent magnet, and has high control accuracy and ratio of performance to price.
Description
Technical field
The present invention relates to a kind of large-scale medical imaging device, specifically a kind of permanent magnet type magnetic resonance imaging system magnet thermostatically-controlled equipment and method.
Background technology
Nuclear magnetic resonance (MRI, Magnetic Resonance Imaging) is new and high technology according to the performance characteristic imaging of organism magnetic core (proton) in magnetic field, widely being applied to clinical medicine image field, is one of diagnostic device most advanced, the most expensive in the present medical image field.
The permanent-magnet type magnetic resonance imaging system is made up of permanent-magnet type magnet subsystem, gradient subsystem, Radio Frequency Subsystem, computer and image processing subsystem etc., wherein the permanent-magnet type magnet is the critical component of magnetic resonance imaging system, its performance is directly connected to the signal to noise ratio of system, thereby is determining the quality of image to a certain extent.
The permanent-magnet type magnet produces an even magnetostatic field in imaging space, be commonly referred to main field, its magnetic field intensity B
0Expression (unit is a tesla, represents with tee).The performance indications of estimating the permanent-magnet type magnet mainly contain four: main field strength, magnetic field homogeneity, stability and effective aperture.The permanent-magnet type magnet is made of strong magnetic material neodymium iron boron and other material.Because the temperature coefficient of neodymium iron boron is promptly very responsive to variations in temperature, make the heat stability variation in its magnetic field, the central frequency deviation of magnetic resonance imaging system and influence the normal scan of magnetic resonance imaging system.
In this system, each controls adjusting of parameter is very important, and the quality that parameter is provided with directly has influence on the performance indications of control system, i.e. control accuracy.If it is bad that parameter is provided with, cause system's diverging oscillation or self-sustained oscillation, the mid frequency ω of magnet
0(ω
0=γ B
0, wherein γ is a gyromagnetic ratio, the hydrogen proton
1The H gyromagnetic ratio is 42.56MHz/T) also can constantly change along with the vibration of magnet temperature, influence the quality of image.
In order to improve the heat stability of permanent-magnet type magnet, usually the thermostatic control system by configuration permanent-magnet type magnet solves this problem, available technology adopting exchanges heating, though can guarantee the permanent-magnet type magnet works under constant temperature, but its alternating current has produced electromagnetic field when exchanging heating, equally magnetic resonance system has been caused influence, simultaneously because controlled device is the permanent-magnet type magnet of about 13 tons or 20 tons weights, lag time is longer, can not obtain the control parameter K of PID in the thermostatic control system with the automatic setting method of routine
p, T
iAnd T
dScope.
Summary of the invention
But the object of the present invention is to provide the heat stability of a kind of Fast Heating and raising permanent-magnet type magnet, thereby magnetic resonance imaging system is normally scanned, make picture quality satisfy the permanent magnet type magnetic resonance imaging system magnet thermostatically-controlled equipment and the method for the requirement of medical diagnosis.
For achieving the above object, the technical solution used in the present invention is:
Permanent magnet type magnetic resonance imaging system magnet thermostatically-controlled equipment of the present invention has the interchange temperature-control circuit, the signal input part of temperature controller is connected to temperature sensor, the adjusting outfan of temperature controller is connected in the ac power supply circuit of alternating current calandria by exchanging the executor, it is characterized in that: also have by temperature sensor, temperature controller, the direct current temperature-control circuit that dc source and unidirectional current calandria constitute, the adjusting outfan of wherein said temperature controller is connected to by the DC heating executor in the direct current power supply loop of unidirectional current calandria, and the warning outfan of temperature controller adds in the ac power supply circuit that thermal actuator is connected to the alternating current calandria by interchange; Supply terminals at signal output part, unidirectional current calandria and the alternating current calandria of temperature sensor is respectively equipped with wave filter; There is temperature control program in the described temperature control device.
Described unidirectional current calandria is a direct current silica gel heating plate; Described alternating current calandria is the AC Electric Heater cable; Described direct current executor is a solid-state relay, and the interchange executor is an A.C. contactor; Described temperature sensor is a platinum resistance sensor; The described wave filter of being located at temperature sensor signal outfan, unidirectional current calandria and alternating current calandria supply terminals is respectively signal feed-through wave filter, dc source feed-through filter and alternating current power supply feed-through filter; Surface at described permanent-magnet type magnet is provided with insulation material.
Permanent magnet type magnetic resonance imaging system magnet constant-temperature control method of the present invention, when magnetic resonance imaging system scans, the alternating current calandria is not worked, has only the work of unidirectional current calandria, when magnetic resonance imaging system does not scan, adopt AC and DC to heat simultaneously under different temperatures or the independent mode of conversion automatically that heats also of direct current, its control procedure of pressing temperature control program is as follows:
A. at first system powers on, and program initialization is provided with in temperature controller and respectively controls parameter;
B. temperature controller is by the temperature of the signal measurement permanent-magnet type magnet of temperature sensor input;
C. judge whether detected permanent-magnet type magnet temperature is lower than interchange heating limit value;
D. said process c judges as for being that then the warning outfan output alarm signal of temperature controller heats alternating current calandria and unidirectional current calandria by interchange and direct current executor simultaneously by the PID mode under the control of temperature controller;
E. said process c judges as is not, and then the warning outfan of temperature controller stops the output of reporting to the police, and stops to exchange and heats, and controls DC heating by the PID mode;
Is f. the temperature of judging the permanent-magnet type magnet higher than the goal setting value?
G. said process g judged result then stops DC heating as for being, otherwise goes to process b.
Proportionality coefficient K wherein is set in said process a when respectively controlling parameter
pBe 1～10, integration time constant T
iBe 1～100 second, derivative time constant T
dIt is 1～100 second; The aforementioned proportion COEFFICIENT K
p, integration time constant T
iAnd derivative time constant T
dBe preferably 1, off, off; In above-mentioned control procedure, also can adopt the method for manual adjustment output compensation to adjust integral coefficient.
The present invention has following beneficial effect and advantage:
1. improved the heat stability of permanent-magnet type magnet.Because apparatus of the present invention adopt the mode of AC and DC heating and automatic conversion, make magnet temperature be heated to the set goal value apace by exchanging heating; Reach more safely when making the magnetic resonance imaging system scanning work and weakened the influence of the electromagnetic field that produces because of alternating current greatly magnetic resonance image (MRI) by DC heating, simultaneously, selected lower DC heating power to keep the thermal balance of permanent-magnet type magnet, reduced the overshoot of system, the side-play amount of when scanning magnetic resonance imaging system mid frequency is reduced to original below 50%, thereby obviously improved picture quality;
2. control accuracy height.Because the inventive method adopts the PID process control, by regulate the control parameter realize the permanent-magnet type magnet from sad temperature function, the variations in temperature of permanent-magnet type magnet is controlled at ± 0.05 ℃ of scope in;
3. P/C is than high.Though the present invention has set up the DC heating part existing the interchange on the basis of heating, cost increases to some extent, and performance is obviously improved.
Description of drawings
Fig. 1 is the operation principle block diagram of magnet thermostatically-controlled equipment of the present invention;
Fig. 2 is the electrical schematic diagram of magnet thermostatically-controlled equipment of the present invention;
Fig. 3 is the flow chart of magnet constant-temperature control method of the present invention;
Fig. 4 is the flow chart of parameter setting among the embodiment of magnet constant-temperature control method of the present invention.
The specific embodiment
Embodiment 1
The present invention designs for the heat stability that improves permanent magnetic field in the permanent magnet type magnetic resonance imaging system, its homothermic automatic control realizes by closed-loop fashion, operation principle as shown in Figure 1, goal setting value r (t) deducts measured value y (t), obtain deviation e (t), deviation e (t) is exactly the input quantity of PID process actuator, the controlled quentity controlled variable u (t) of PID process actuator as shown in Equation (1):
u(t)＝K
p[e(t)+1/T
i∫e(t)dt+T
d×de(t)/dt] (1)
Wherein: K
pBe proportionality coefficient;
T
iBe integration time constant;
T
dBe derivative time constant;
Choose suitable K
p, T
iAnd T
dMake the dutycycle of controlled quentity controlled variable u (t) the control solid-state relay of actuator, thereby the output of control electric heating body makes permanent-magnet type magnet control accuracy within ± 0.05 ℃.
Based on above control principle, adopt the two-way temperature-control circuit in apparatus of the present invention, be respectively applied for detect and control permanent-magnet type magnet on the temperature of cartridge and following cartridge, as shown in Figure 2, the structure of this two-way temperature-control circuit is identical, have the 1st respectively, 2 temperature sensor TE1, TE2 (all adopting platinum resistance temperature sensor in the present embodiment), the 1st, 2 temperature controller TC1, (present embodiment all adopts SR50 series high-performance PID process actuator to TC2,) and hand over, the unidirectional current calandria, the unidirectional current calandria adopts two groups of direct current silica gel heating plates (every group is two) in the present embodiment, promptly the 1st, 2 groups of direct current silica gel heating plate EH1, EH2 sticks on two columns of permanent-magnet type magnet respectively with heat conductive silica gel, wherein two of the 1st group stick on top, and two of the 2nd group stick on the bottom; The alternating current calandria adopts two AC Electric Heater cables, i.e. the 1st, 2 AC Electric Heater cable EH3, EH4 stick on the side surface of cartridge and following cartridge respectively with heat conductive silica gel; Two temperature sensors, promptly the 1st, 2 temperature sensor TE1, TE2 are installed in the centre position of the last cartridge and the following cartridge of permanent-magnet type magnet respectively; Each element of in the temperature-control circuit other is assembled in the rustless steel cabinet, and be installed on the conductive plate between magnet chamber and the canyon, outer surface at whole permanent-magnet type magnet also is pasted with the low-down insulation material of heat conductivity, to reduce influence and the raising control accuracy of ambient temperature to the permanent-magnet type magnet.
The electrical structure of this device is that example is described as follows with the control circuit at the 1st temperature controller TC1 place: the signal input part of the 1st temperature controller TC1 links to each other with the 1st temperature sensor TE1, the adjusting outfan of the 1st temperature controller TC1 is connected in the direct current power supply loop of the 1st group of direct current silica gel heating plate EH1 by DC heating executor (present embodiment adopts the 1st solid-state relay SSR1), and the warning outfan of the 1st temperature controller TC1 adds thermal actuator (present embodiment adopts the 1st A.C. contactor KM1) by interchange and is connected in the ac power supply circuit of the 1st AC Electric Heater cable EH3; Supply terminals at the signal output part of the 1st temperature sensor TE1, the 1st group of direct current silica gel heating plate EH1 and the 1st AC Electric Heater cable EH3 is respectively equipped with the 1st～3 signal feed-through wave filter FL1～FL3, the 1st～2 dc source feed-through filter FL7～the 8 and the 1st～2 alternating current power supply feed-through filter FL11～12; The power input of the 1st temperature controller TC1 is connected to ac working power supply; There is temperature control program in the described temperature control device.
SR50 series high-performance PID process actuator, certainty of measurement is 0.25% of a measuring range, figure place showing is four, because measuring range is set at 0 ℃～50 ℃, therefore, the show value of measured value is in 0.00 ℃～50.00 ℃, the arithmetic point back can show two digits, be very easy to field personnel's shimming work, simultaneously, also improved the even equal property of main field.
The inventive method as shown in Figure 3, in the permanent magnet type magnetic resonance imaging system, during magnetic resonance imaging system scanning, the alternating current calandria is not worked, has only the work of unidirectional current calandria, when magnetic resonance imaging system does not scan, adopt AC and DC to heat simultaneously under different temperatures or the independent mode of conversion automatically that heats also of direct current, its control procedure of pressing temperature control program is as follows:
A. at first system powers on, and program initialization is provided with in temperature controller and respectively controls parameter;
B. temperature controller is by the temperature of the signal measurement permanent-magnet type magnet of temperature sensor input;
C. judge whether detected permanent-magnet type magnet temperature is lower than interchange heating limit value;
D. said process c judges as for being, the warning outfan output alarm signal of temperature controller then, add thermal actuator and DC heating executor by interchange and make alternating current calandria step-by-step formula (switching value) control heating, the unidirectional current calandria heats by the PID mode under the control of temperature controller simultaneously;
E. said process c judges as is not, and then the warning outfan of temperature controller stops the output of reporting to the police, and stops to exchange and heats;
Is f. the temperature of judging the permanent-magnet type magnet higher than the goal setting value?
G. said process g judged result then stops DC heating as for being, otherwise goes to process b.
In above-mentioned control procedure, also can adopt the method for manual adjustment output compensation to adjust integral coefficient T
i
In said process a, be provided with and respectively control the parameter setting process as shown in Figure 4:
S1: the desired value of setting expection control;
S2: set and exchange the heating limit value;
S3: set the control parameter proportional band P value of DC heating, its set point is 0.1～999.9%FS, and the range of choice is 0.1～1 in this device, and step-length is 0.1, and the present invention is K
p=1～10;
S4: set the control parameter integral time of DC heating, its set point is 1～6000 second, and the range of choice is 1～100 second in this device, and step-length is 10 seconds, and the present invention is T
i=1～100 seconds;
S5: set the control parameter derivative time of DC heating, its set point is 1～3600 second, and the range of choice is 1～100 second in this device, and step-length is 10 seconds, and the present invention is T
d=1～100 seconds;
S6: set the control parameter manual adjustment output compensation of DC heating, its set point is-50～+ 50, overcomes system's static difference;
S7: setting measurement value lower limit, the present embodiment setting value is 0 ℃;
S8: the setting measurement value upper limit, the present embodiment setting value is 50 ℃;
S9: measured value unit sets, and present embodiment is selected degree centigrade;
S10: the platinum resistance measurement range selection, present embodiment is selected " Pt 5 ", and its measuring range is 0～50 ℃, and the measured value arithmetic point back that makes temp controlled meter show has two;
S11: the sampling period is set, and its scope is at 4～20ms, and present embodiment is set 4ms;
S12: export positive and negative effect setting, the present invention is owing to be to add thermal control, and therefore, present embodiment is set at the retroaction mode;
S13: exchange the heating output type and set, present embodiment is set at the lower limit absolute value output of measured value and setting value, that is to say, when measured value is lower than when exchanging the heating limit value, is output as ON, when measured value is higher than when exchanging the heating limit value, is output as OFF;
S14: interchange adds the thermal control return difference to be set, and set point is 0.2%～10%FS, and wherein FS is a full scale;
S15: setting value and ordering parameter locking, revise setting value and ordering parameter for forbidding the irrelevant personnel.
Control principle of the present invention as shown in Figure 1, exchange heating limit value r ' (t) when being higher than measured value y (t), r ' (t) deducts measured value y (t), obtain deviation e ' (t), deviation e ' is the input quantity of temperature controller meta formula regulating and controlling (being that switching value is regulated) (t), as deviation e ' (t)＞0 time, be that measured value y (t) is lower than when exchanging the heating limit value, this system's AC and DC heats simultaneously, make the temperature of magnet approach desired value fast, after temperature reaches interchange heating limit value, exchange output and stop heating automatically, direct current continues to be heated to the goal setting value; If e ' (t)≤0, promptly measured value has reached and has exchanged the heating limit value, then exchanges calandria and stops heating automatically, and system controls DC heating by pid control mode, reaches the desired value of setting expection control in process S1 up to detected temperatures.
Because controlled device is the permanent-magnet type magnet of about 13 tons or 20 tons weights, lag time is longer, can not obtain K with the automatic setting method of routine
p, T
iAnd T
dParameter.According to applicant's experience in practice, the K of process S3～5 in the present embodiment
pSetting value is at 1～10 scope, T
iSetting value is at 1～10 second, T
dSetting value is at 1～10 second, in the present embodiment these three parameters respectively be 1, off, off, make this system response time the shortest, stability is best.After tested, the side-play amount of the permanent magnet type magnetic resonance imaging system magnet center frequency of first kind of model from former ± 1000Hz be reduced to ± (the magnet center frequency of the permanent magnet type magnetic resonance imaging system of this first kind of model is 9.7888 * 10 to 400Hz
6Hz); The side-play amount of the permanent magnet type magnetic resonance imaging system magnet center frequency of second kind of model from former ± 1200Hz be reduced to ± (the magnet center frequency of the permanent magnet type magnetic resonance imaging system of this second kind of model is 1.4896 * 10 to 500Hz
7Hz);
Process S1 sets and expects that the desired value of control is 32 ℃ in the present embodiment; Process S2 sets and exchanges the heating limit value is 31.5 ℃; For avoiding A.C. contactor misoperation and frequent movement, the temperature control controller is provided with 0.2% return difference in process S14, is equivalent to 0.1 ℃; The process S11 sampling period is set at 4ms.
When if its measured value of the stable back of magnet temperature is higher or lower than setting value a little, overcome system's static difference by manual adjustment output compensation Mr value, the control accuracy of control system is reached ± 0.05 ℃ within, the adjustment percentage ratio of manual adjustment output compensation Mr is in-50～+ 50 scopes, and default value is 0.
Be with the difference of embodiment 1, in the present embodiment the K of process S3～5
p, T
i, T
dSetup parameter respectively was 10,100 seconds, 100 seconds, and through test, this system response time is short, stability is better.After tested, the side-play amount of the magnet center frequency of the permanent magnet type magnetic resonance imaging system of first kind of model is reduced to ± 700Hz from former ± 1500Hz; The side-play amount of the permanent magnet type magnetic resonance imaging system magnet center frequency of second kind of model is reduced to ± 1100Hz from former ± 2200Hz.
In the shimming of reality, if+Z6～+ Z1 (demarcate by the relative physical location in the action of a magnetic field zone, total-Z6～+ 13 zones of Z6) field strength values in the scope is greater than the magnet center frequency values, then will increase the Mr value that goes up cartridge the 1st temperature controller TC1; If+Z6～+ field strength values in the Z1 scope then will reduce to go up the Mr value of cartridge the 1st temperature controller TC1 less than the magnet center frequency values; If-Z6～-field strength values in the Z1 scope then will increase the Mr value of cartridge the 2nd temperature controller TC2 down greater than the magnet center frequency values; If-Z6～-field strength values in the Z1 scope then will reduce the Mr value of cartridge the 2nd temperature controller TC2 down less than the magnet center frequency values.By the value of regulating manual adjustment output compensation Mr reduce+Z6～+ Z1 and-Z6～-difference between the Z1, not only improved the precision of control system, also reached the purpose of saving the shimming magnetic sheet.
The purpose that the present invention keeps original interchange heating is in order to make magnet temperature be heated to the set goal value apace; The purpose of setting up DC heating is the influence of the magnetic field that produces because of alternating current of the safety problem when considering the magnetic resonance imaging system scanning work and eliminate to magnetic resonance image (MRI).
Claims (10)
1. permanent magnet type magnetic resonance imaging system magnet thermostatically-controlled equipment, has the interchange temperature-control circuit, the signal input part of temperature controller is connected to temperature sensor, the adjusting outfan of temperature controller is connected in the ac power supply circuit of alternating current calandria by exchanging the executor, it is characterized in that: also have by temperature sensor, temperature controller, the direct current temperature-control circuit that dc source and unidirectional current calandria constitute, the adjusting outfan of wherein said temperature controller is connected to by the DC heating executor in the direct current power supply loop of unidirectional current calandria, and the warning outfan of temperature controller adds in the ac power supply circuit that thermal actuator is connected to the alternating current calandria by interchange; Supply terminals at signal output part, unidirectional current calandria and the alternating current calandria of temperature sensor is respectively equipped with wave filter; There is temperature control program in the described temperature control device.
2. by the described permanent magnet type magnetic resonance imaging system of claim 1 magnet thermostatically-controlled equipment, it is characterized in that: described unidirectional current calandria is a direct current silica gel heating plate; Described alternating current calandria is the AC Electric Heater cable.
3. by the described permanent magnet type magnetic resonance imaging system of claim 1 magnet thermostatically-controlled equipment, it is characterized in that: described direct current executor is solid-state relay, and the interchange executor is an A.C. contactor.
4. by the described permanent magnet type magnetic resonance imaging system of claim 1 magnet thermostatically-controlled equipment, it is characterized in that: described temperature sensor is a platinum resistance sensor.
5. by the described permanent magnet type magnetic resonance imaging system of claim 1 magnet thermostatically-controlled equipment, it is characterized in that: the described wave filter of being located at temperature sensor signal outfan, unidirectional current calandria and alternating current calandria supply terminals is respectively signal feed-through wave filter, dc source feed-through filter and alternating current power supply feed-through filter.
6. by the described permanent magnet type magnetic resonance imaging system of claim 1 magnet thermostatically-controlled equipment, it is characterized in that: the surface at described permanent-magnet type magnet is provided with insulation material.
7. permanent magnet type magnetic resonance imaging system magnet constant-temperature control method is characterized in that:
During magnetic resonance imaging system scanning, the alternating current calandria is not worked, and has only the work of unidirectional current calandria, when magnetic resonance imaging system does not scan, adopt AC and DC to heat simultaneously under different temperatures or the independent mode of conversion automatically that heats also of direct current, its control procedure of pressing temperature control program is as follows:
A. at first system powers on, and program initialization is provided with in temperature controller and respectively controls parameter;
B. temperature controller is by the temperature of the signal measurement permanent-magnet type magnet of temperature sensor input;
C. judge whether detected permanent-magnet type magnet temperature is lower than interchange heating limit value;
D. said process c judges as for being that then the warning outfan output alarm signal of temperature controller heats alternating current calandria and unidirectional current calandria by interchange and direct current executor simultaneously by the PID mode under the control of temperature controller;
E. said process c judges as is not, and then the warning outfan of temperature controller stops the output of reporting to the police, and stops to exchange and heats, and controls DC heating by the PID mode;
Is f. the temperature of judging the permanent-magnet type magnet higher than the goal setting value?
G. said process g judged result then stops DC heating as for being, otherwise goes to process b.
8. by the described permanent magnet type magnetic resonance imaging system of claim 7 magnet constant-temperature control method, it is characterized in that: proportionality coefficient K wherein is set in said process a when respectively controlling parameter
pBe 1～10, integration time constant T
iBe 1～100 second, derivative time constant T
dIt is 1～100 second.
9. by the described permanent magnet type magnetic resonance imaging system of claim 8 magnet constant-temperature control method, it is characterized in that: the aforementioned proportion COEFFICIENT K
p, integration time constant T
iAnd derivative time constant T
dBe respectively 1, off, off.
10. by the described permanent magnet type magnetic resonance imaging system of claim 7 magnet constant-temperature control method, it is characterized in that: in above-mentioned control procedure, also can adopt the method for manual adjustment output compensation to adjust integral coefficient.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005101367521A CN100490739C (en) | 2005-12-29 | 2005-12-29 | Magnetic body thermostatic control device and method for permanent-magnet magnetic resonance imaging systems |
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|---|---|---|---|
| CNB2005101367521A CN100490739C (en) | 2005-12-29 | 2005-12-29 | Magnetic body thermostatic control device and method for permanent-magnet magnetic resonance imaging systems |
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| CN100490739C CN100490739C (en) | 2009-05-27 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101776924B (en) * | 2009-01-12 | 2013-09-11 | 孙继海 | Full automatic digital instrument with dynamic PID technology and overshoot suppression |
| CN104237817B (en) * | 2014-09-26 | 2016-11-30 | 苏州露宇电子科技有限公司 | Nmr magnet thermostat |
| CN112925364A (en) * | 2021-02-02 | 2021-06-08 | 深圳量旋科技有限公司 | Temperature control method and system based on simple pendulum physical model and storage medium |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP6716591B2 (en) | 2015-03-02 | 2020-07-01 | カイオ セラピー，エルエルシー | System and method for providing alternating magnetic field therapy |
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2005
- 2005-12-29 CN CNB2005101367521A patent/CN100490739C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101776924B (en) * | 2009-01-12 | 2013-09-11 | 孙继海 | Full automatic digital instrument with dynamic PID technology and overshoot suppression |
| CN104237817B (en) * | 2014-09-26 | 2016-11-30 | 苏州露宇电子科技有限公司 | Nmr magnet thermostat |
| CN112925364A (en) * | 2021-02-02 | 2021-06-08 | 深圳量旋科技有限公司 | Temperature control method and system based on simple pendulum physical model and storage medium |
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|---|---|
| CN100490739C (en) | 2009-05-27 |
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