CN101965093A - High pressure generator calibration method - Google Patents

Abstract

The invention discloses a high pressure generator calibration method comprising the following steps: A1, measuring the practical resistance value of feedback divider resistor and the practical resistance value of series resistors of the high pressure generator; A2, calculating a feedback error; and A3, according to the feedback error and the amplification reference of the high pressure generator, controlling the exposure process of the high pressure generator. The high pressure generator calibration method of the invention automatically calibrates the feedback error caused by the tank series resistors of the high pressure generator with a soft approach, has simple calibration step, simple operation, short calibration time and low error probability, and does not need to use a special instrument.

Description

A kind of high pressure generator calibration steps

Technical field

The present invention relates to the radiation filming system technical field, be specifically related to a kind of radiation filming system high pressure generator calibration steps.

Background technology

As shown in Figure 1, radiation filming system utilizes the 40-150KV and the heater current of high pressure generator output, make bulb produce X ray, after X ray penetrates tissue, difference because of tissue, the attenuation degree of X ray is different, utilizes x-ray imaging system the X ray of decay to be changed into the image of tissue.

As shown in Figure 2, the high pressure generator operation principle is earlier power-frequency voltage to be become the direct voltage of low-ripple coefficient through rectification, filtering, produces high frequency voltage by inverse transformation then, and the X bulb is exported in the boosting of the transformer in tank, rectification, filtering then.The stability of high pressure generator and consistency have determined the quality of x-ray imaging.

As shown in Figure 3, the medical diagnosis X radial bulb needs the high pressure of high pressure generator output 40KV to 150KV, and the control desk of high pressure generator and master board are the digital signal and the analog signal of low pressure, and the scope of KV set point is between 0 to 10 volt.So proportionate relationship K between KV set point and the high pressure generator actual high-voltage output valve _Set(high pressure generator amplification reference value) is the corresponding 10 several KV of 1V, is defined as K here _Set=1V:nKV for example will export 100KV, and the KV set point is so

Because production technology, tank does not have consistency, mainly shows two aspects: 1, the transformer leakage inductance value of different tank inside has difference.2, the KV of tank inside feedback dividing potential drop series resistance quantity is more, and the error of single resistance is 5%, and accumulated error is bigger.Existing calibration steps all is to add the error that the sampling feedback correcting circuit compensates series connection divider resistance in the tank on inversion drives.The KV set point that the master control borad of high pressure generator is set according to control desk, by KV set point and the certain proportionate relationship of KV value, utilize the digital analog converter DAC in the master board, the KV set point is converted to corresponding KV reference voltage, deliver in the error amplifier of inversion drive plate.The KV value of feedback need enter into error amplifier through a potentiometer, and this potentiometer is the error that is used for correcting the tank series resistance.KV set point and KV value of feedback are done computing through error amplifier like this, and operation result control inversion produces corresponding KV value.The hardware calibration method of prior art, following shortcoming is arranged: calibration process is loaded down with trivial details, the step complexity, the alignment time is long, needs to use special instrument, must be operated by the expert engineer, and error probability is higher.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of high pressure generator calibration steps, overcomes the defective that the prior art high pressure generator is eliminated the loaded down with trivial details complexity of calibration steps of tank series resistance error, appearance mistake easily.

The present invention solves the problems of the technologies described above the technical scheme that is adopted to be:

A kind of high pressure generator calibration steps comprises step:

A1, the actual resistance of measuring high pressure generator feedback divider resistance and the actual resistance of series resistance;

A2, calculating feedback error;

A3, amplify reference value according to described feedback error and high pressure generator the high pressure generator exposure process is controlled.

Described high pressure generator calibration steps, wherein said steps A 1 comprises step:

B1, the actual resistance of measuring high pressure generator feedback divider resistance and the actual resistance of series resistance;

The ratio K of B2, the described feedback divider resistance actual resistance of storage and described series resistance actual resistance ' _FD

Described high pressure generator calibration steps, wherein said steps A 2 comprises step:

B3, the theoretical resistance of calculating high pressure generator feedback divider resistance and the theoretical resistance of series resistance;

The ratio K of B4, the theoretical resistance of the described feedback divider resistance of storage and the theoretical resistance of described series resistance _FD

B5, calculating K ' _FDWith K _FDDifference, store the long-pending Δ K that described difference is multiplied by a fixed constant _Set

B6, calculating K _FDLong-pending K with described fixed constant _Set

Described high pressure generator calibration steps is wherein with K _SetWith Δ K _SetAnd the PDM keyer that after digital-to-analogue conversion, outputs to high pressure generator.

Beneficial effect of the present invention: high pressure generator calibration steps of the present invention is calibrated the feedback error that high pressure generator tank series resistance causes automatically by software approach, calibration steps is simple, operation easily, and the alignment time is short, and do not need to use special instrument, error probability is low.

Description of drawings

The present invention includes following accompanying drawing:

Fig. 1 is a prior art radiation filming system schematic diagram;

Fig. 2 is a prior art radiation filming system high pressure generator schematic diagram;

Fig. 3 is a prior art radiation filming system high pressure generator tank series resistance error calibration circuit schematic diagram;

Fig. 4 is a high pressure generator tank feedback sample resistance schematic diagram of the present invention;

Fig. 5 is a radiation filming system high pressure generator tank series resistance error calibration circuit schematic diagram of the present invention;

Fig. 6 is a PDM keyer schematic diagram of the present invention;

Fig. 7 is a filament inverter circuit schematic diagram of the present invention;

Fig. 8 is a feedback circuit schematic diagram of the present invention.

Embodiment

With embodiment the present invention is described in further detail with reference to the accompanying drawings below:

As shown in Figure 4, at first measure the actual resistance (R of high pressure generator feedback divider resistance _N± Δ R) actual resistance of series resistance

Other circuit in series connection bleeder circuit and the tank are disconnected, make the series connection bleeder circuit constitute an independent loop, test the resistance of series resistance in the tank respectively with the LCR tester, and note.According to following formula, calculate actual feedback and amplify reference value K ' _FD:

$K_{\mathrm{FD}}^{\′}=\frac{R_N\±\mathrm{\ΔR}}{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}(R_i\±\mathrm{\ΔR})}$

Theoretical resistance and the theoretical resistance calculating of series resistance and ratio (the theoretical feedback the amplified reference value) K of theoretical resistance of store feedback divider resistance and the theoretical resistance of described series resistance according to high pressure generator feedback divider resistance _FD

High pressure generator amplifies reference value K _SetAmplify reference value K with the theory feedback _FDSatisfy following relation:

K _set＝C×K _FD

Wherein C is a fixed constant.And exist owing to the series resistance error in the high pressure generator side circuit, so the actual high-voltage generator amplifies reference value K ' _SetShould with feedback error (K ' _FDWith K _FDPoor) take into account:

K′ _set＝C(K _FD+ΔK _FD)

Feedback error Δ K wherein _FD=K ' _FD-K _FD

If Δ K _Set=C Δ K _FD

So: K ' _Set=K _Set+ Δ K _Set

When high pressure generator assembling or replacing tank, in the service mode of high pressure generator control desk, K ' is set _FDParameter and K _FDParameter.In the memory of master board, open up a memory cell, be used for storing K ' _FDParameter and K _FDParameter.The CPU of master control borad calculates Δ K according to following formula _Set:

ΔK _set＝CΔK _FD＝C(K′ _FD-K _FD)

As shown in Figure 5 and Figure 6, high pressure generator in exposure process with K ' _SetConvert the PDM keyer (PWM that voltage signal sends to the inversion control plate to, Pulse Width Modulation) error amplifier comparator one end, when receiving adjustment signal FIL REF, PWM controller (chip TL954) will be adjusted the duty ratio of its output, inversion drives and also obtains adjusting, thereby adjusts the electric current in the filament loop, after heater current changes, the electric current of bulb (load current) has also changed, thereby output KV value also changes thereupon.

As shown in Figure 7, the voltage signal (FIL_REF signal) of DAC output compares with feedback signal FIL_I, thus the duty ratio of the output drive signal of 9 pin of adjustment chip TL594,10 pin.This output drive signal is the inversion drive signal, by switch Q1, Q2, Q3 and Q4, arrives and adjusts filament loop, i.e. current circuit among the FIL_DR_OUT.

As shown in Figure 8, filament transformer receives in the variation of FIL_DR_OUT electric current in tank, because the equivalence of transformer transmission principle, after the FIL_DR_OUT electrorheological is big, the electric current of the opposite side of filament transformer also will become greatly, and promptly the tube current of bulb will become big.Bulb is the load of high pressure generator, because the tank gross energy is certain, so when load current changes, also will influence the variation of output KV voltage.After output KV voltage changes, also will change by the KV feedback voltage of resistance sampling, the KV feedback is received an end of PWM controller, and then adjusts the size of PWM controller duty ratio, forms closed-loop adjustment.

Those skilled in the art do not break away from essence of the present invention and spirit, can there be the various deformation scheme to realize the present invention, the above only is the preferable feasible embodiment of the present invention, be not so limit to interest field of the present invention, the equivalent structure that all utilizations specification of the present invention and accompanying drawing content are done changes, and all is contained within the interest field of the present invention.

Claims (4)

1. a high pressure generator calibration steps is characterized in that, comprises step:

A1, the actual resistance of measuring high pressure generator feedback divider resistance and the actual resistance of series resistance;

A2, calculating feedback error;

A3, amplify reference value according to described feedback error and high pressure generator the high pressure generator exposure process is controlled.

2. high pressure generator calibration steps according to claim 1 is characterized in that, described steps A 1 comprises step:

B1, the actual resistance of measuring high pressure generator feedback divider resistance and the actual resistance of series resistance;

The ratio K of B2, the described feedback divider resistance actual resistance of storage and described series resistance actual resistance ' _FD

3. high pressure generator calibration steps according to claim 2 is characterized in that, described steps A 2 comprises step:

B3, the theoretical resistance of calculating high pressure generator feedback divider resistance and the theoretical resistance of series resistance;

The ratio K of B4, the theoretical resistance of the described feedback divider resistance of storage and the theoretical resistance of described series resistance _FD

B5, calculating K ' _FDWith K _FDDifference, store the long-pending Δ K that described difference is multiplied by a fixed constant _Set

B6, calculating K _FDLong-pending K with described fixed constant _Set

4. high pressure generator calibration steps according to claim 3 is characterized in that: with K _SetWith Δ K _SetAnd the PDM keyer that after digital-to-analogue conversion, outputs to high pressure generator.

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