WO2005088814A1

WO2005088814A1 - Power converter, inverter x-ray high voltage unit, fluoroscopic system, x-ray ct system, mri system

Info

Publication number: WO2005088814A1
Application number: PCT/JP2005/004172
Authority: WO
Inventors: Takatsugu Oketa; Jun Takahashi; Hiroshi Takano
Original assignee: Hitachi Medical Corporation
Priority date: 2004-03-15
Filing date: 2005-03-10
Publication date: 2005-09-22
Also published as: JPWO2005088814A1; CN100553086C; CN1930766A; JP4526130B2

Abstract

A power converter comprising a converter for rectifying a commercial AC voltage to produce a DC voltage, a capacitor for smoothing the DC voltage, an inverter for converting the smoothed DC voltage into an AC voltage of a specified frequency, a means for measuring the charge/discharge characteristics of the capacitor every time when the power converter is used, a storing for previously measuring the charge/discharge characteristics of the capacitor in an initial state by that measuring means and storing the measured characteristics, a means for comparing the charge/discharge characteristics measured every time when the power converter is used with the charge/discharge characteristics in an initial state thus stored, a means for judging deteriorated state of the capacitor based on the comparison results, and a means for informing the deteriorated state of the capacitor. Since a trouble incident to deterioration of the capacitor can be prevented, high reliability can be ensured as a stabilized power supply for a medical image diagnostic system.

Description

Specification

Power conversion equipment, inverter X-ray high-voltage equipment, X-ray fluoroscopy equipment, X-ray CT equipment, MRI equipment

Technical field

The present invention relates to an inverter X-ray high-voltage device, an X-ray fluoroscopic device, an X-ray CT device,

In the field of power converters used as power supplies for medical image diagnostic equipment including MRI (Magnetic Resonance Imaging) equipment, observe the deterioration of capacitors provided at the input stage of the inverter, and observe the deterioration of the capacitors. The present invention relates to a technology for avoiding a failure of a power conversion device and securing high reliability by avoiding the failure.

Background art

[0002] The power converter includes an AC rear turtle connected to a commercial power supply, a converter circuit connected to the AC rear turtle, a capacitor connected to the converter circuit, and an inverter circuit connected to the capacitor. It has a transformer connected to the inverter circuit, a rectifier circuit connected to the transformer, and a load.

[0003] Commercial AC power is supplied to the AC rear turtle. The converter circuit converts (rectifies) the AC voltage of the AC reactor to DC voltage. The capacitor removes (smooths) the Lipnore component superimposed on the DC voltage rectified by the converter circuit. The inverter circuit converts the DC voltage smoothed by the capacitor into a high-frequency AC voltage. The high-voltage transformer boosts the high-frequency AC voltage converted by the inverter circuit to an AC high voltage. The rectifier circuit rectifies the high AC voltage boosted by the transformer into a high DC voltage. The load is an X-ray tube or a gradient coil of a magnetic resonance imaging apparatus.

[0004] Here, the capacitor itself generates heat due to the ripple current flowing during each smoothing operation, and depending on the heat generation and the use environment, the dielectric material of the capacitor or the electrolytic solution in the electrolytic capacitor may lose its electrolyte. It deteriorates each time the power converter is used. Deterioration of the capacitor not only causes the smoothing function to stop working, but also allows the inverter circuit to properly operate by supplying the lip-nore component not removed by the smoothing function to the inverter circuit. It does not work and the power converter breaks down.

Then, there is [Patent Literature 1] as one method of coping with capacitor deterioration.

[0005] [Patent Document 1] discloses a measuring means for measuring any one of the capacitor's capacitance, tan δ, leakage current, and impedance, and a measurement result obtained by the measuring means. Storage means for sequentially storing the data; and determination means for determining the deterioration of the capacitor based on the result stored in the storage means. Is predicted and displayed.

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-267708

[0006] However, the measure of [Patent Document 1] is to diagnose the deterioration of the capacitor without removing the electrolytic capacitor mounted on the substrate of the signal processing circuit from the circuit. The following items are still lacking in order to meet the demand for high reliability of power converters applied as power sources for devices.

(1) In the power conversion device, deterioration of the capacitor must be determined frequently, and measures must be taken before failure due to deterioration of the capacitor becomes definitive.

However, [Patent Document 1] only describes that the deterioration determination of the capacitor is performed in time series, and does not explain the urgency and importance of the deterioration determination of the capacitor when used in the power converter. So it is not effective.

(2) In [Patent Document 1], since the deterioration judgment of the capacitor uses the characteristic judgment value of the capacitor stored in the database in advance, the influence of the inherent variation of the capacitor on the deterioration of the capacitor itself is considered. Not.

(3) In [Patent Document 1], after determining deterioration failure of a capacitor, a specific warning notification method is taken into consideration.

Disclosure of the invention

[0007] A power conversion device of the present invention provides a converter for rectifying a commercial AC voltage to a DC voltage, a capacitor for smoothing the DC voltage rectified by the converter, and a DC voltage smoothed by the capacitor for converting the DC voltage to a predetermined voltage. An inverter for converting the voltage into an AC voltage, a measuring means for measuring the charge / discharge characteristics of the capacitor each time the power converter is used, and a charge / discharge characteristic of the capacitor in an initial state in advance measured by the measuring means. , That measurement Storage means for storing the charge / discharge characteristics of the capacitor in a defined initial state; charge / discharge characteristics of the capacitor measured by the measuring means each time the capacitor is used; and charge / discharge characteristics of the capacitor in the initial state stored by the storage means. Comparison means for comparing the discharge characteristics; capacitor deterioration determination means for determining the deterioration state of the capacitor based on the result of comparison by the comparison means; and notification of the deterioration state of the capacitor determined by the capacitor deterioration determination means. And a notifying means.

Accordingly, a failure due to the deterioration of the capacitor can be prevented beforehand, so that high reliability can be secured as a stable power supply to be supplied to the medical image diagnostic apparatus.

Brief Description of Drawings

FIG. 1 is a block diagram showing a configuration example of an X-ray fluoroscopic apparatus employing a power conversion device of the present invention.

FIG. 2 is a block diagram showing a configuration example of an X-ray CT apparatus to which the power converter of the present invention is applied.

FIG. 3 is a block diagram showing an embodiment of an inverter type X-ray high voltage device employing the power converter of the present invention.

FIG. 4 is a graph showing a comparison of a voltage drop time until a predetermined voltage value is reached in a voltage drop curve across the capacitor in FIG. 3.

5 is a graph showing a comparison relationship between voltage values at a predetermined falling time in a voltage drop curve across the capacitor in FIG. 3.

FIG. 6 is a block diagram showing a configuration example of an MRI apparatus to which the power converter of the present invention is applied.

FIG. 7 is a block diagram showing a configuration example of a power converter employed in the MRI apparatus of FIG. 6. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

Example 1

In the present embodiment, a case where the load of the power converter is an X-ray tube will be described. Medical diagnostic imaging devices using X-ray tubes include X-ray fluoroscopy devices and X-ray CT devices. The system configuration example of the X-ray fluoroscope is explained using Fig. 1, and the system configuration of the X-ray CT system is shown in Fig. 2. Will be explained.

FIG. 1 is an example of an X-ray fluoroscopic apparatus, which is an example of the configuration of a system used for a C-arm type X-ray fluoroscopic apparatus.

The C-arm X-ray fluoroscope includes an inverter X-ray high-voltage device 100, a bed 101, an image receiving device 102, a monitor 103 connected to the image receiving device 102, a bed 101, an image receiving device 102, and an X-ray tube. A console 104 connected to 107; a support device 106 for supporting the image receiving device 102 and the X-ray tube 107 in opposition; an X-ray tube 107 connected to the inverter X-ray high-voltage device 100 and a high-voltage cable 105; have.

The inverter X-ray high-voltage device 100 is a power conversion device to which an X-ray tube 107 is connected as a load. The bed 101 is a table on which a patient is placed. The image receiving device 102 is a film for receiving an X-ray transmission image transmitted through a patient, an image intensifier (I 丄), an X-ray flat panel detector (FPD), or the like. The monitor 103 displays an X-ray transmission image in the X-ray room. The console 104 has a function of setting X-ray conditions, displaying an X-ray transmission image, and controlling the operations of the X-ray tube 107, the image receiving device 102, and the bed 101. The high voltage cable 105 supplies a high voltage from the inverter X-ray high voltage device 100 to the X-ray tube 107. The support device 106 supports the X-ray tube 107 and the image receiving device 102 so as to face each other. The X-ray tube 107 emits X-rays to the patient.

[0013] The X-ray fluoroscopic apparatus configured as described above operates the couch 101 and the support device 106 to position the region where the patient is to be imaged, and then sets the X-ray conditions on the console 104, Based on the set X-ray conditions, a DC high voltage (tube voltage) is applied from the inverter X-ray high-voltage device 100 to the X-ray tube 107 via the high-voltage cable 105, and the X-ray tube 107 transfers the bed 101 X-rays are applied to the patient placed on The irradiated X-rays pass through the patient and are received by the image receiving device 102. The transmitted image received by the image receiving device 102 is displayed on the monitor 103 and the monitor attached to the console 104.

FIG. 2 shows an example of a system configuration of the X-ray CT apparatus.

The X-ray CT apparatus includes an X-ray tube 201, an X-ray finometer 202 and a collimator 203 provided in the X-ray irradiation direction from the X-ray tube 201, a bed top 204, and an input surface direction of the X-ray detector 206. X-ray grid 205, X-ray detector 206, rotating plate 207, gantry 208, measurement condition setting means 211, imaging control means 212, rotating plate driving means 213, bed moving means 214, image collection It has a collection unit 215, an image processing unit 216, an image display unit 217, and a collimator control unit 218.

An opening 210 is provided at the center of the gantry 208, and a subject 209 is inserted and arranged therein.

[0015] An X-ray generation / detection system including the X-ray tube 201, the X-ray filter 202, the collimator 203, the X-ray grid 205, and the X-ray detector 206 is referred to as an imaging system. The photographing system is fixed to a rotating plate 207 and is rotated by a known drive motor (not shown). The rotation axis of the rotation plate 207 is the Z axis. Also, the horizontal and vertical coordinate axes with the rotation center 原点 as the origin are the X axis and the Y axis, respectively. Furthermore, the rotation angle of the X-ray generation point S with respect to the X axis is Θ.

[0016] X-ray detector 206 is a solid state detector composed of a ceramic scintillator element. In addition, each ceramic scintillator element is arranged on an arc approximately equidistant from the X-ray generation point S.

[0017] The X-ray CT apparatus operates in the following procedure. The examiner sets the measurement area in the Z-axis direction, the imaging mode, and the like of the subject 209 through the measurement condition setting means 211. The measurement condition setting means 211 inputs the information of the set values to the collimator control means 218 and the imaging control means 212. The collimator control means 218 controls the collimator 203 based on the set value and changes the X-ray irradiation area. The imaging control means 212 defines the timing of X-ray generation of the X-ray tube 201 and the imaging timing of the X-ray detector 206 based on the set values. Further, the photographing control unit 212 defines a rotation sequence given to the rotating plate driving unit 213 and a movement sequence given to the bed moving unit 214. Further, the photographing control means 212 also defines a sequence of reading and storing the photographed data to be given to the image collecting means 215. Here, when the operator inputs a scan start command from an operating device (not shown), the rotating plate driving unit 213 uses a known driving motor (not shown) based on the rotation sequence given by the photographing control unit 212. To rotate the rotating plate 207. The couch moving means 214 uses the known couch drive sequence (not shown) based on the couch moving sequence given to the imaging control means 212 to move the couch top 204 and the subject 209 arranged on the couch top 204 along the Z axis. Move in the direction. The X-rays generated from the X-ray tube 201 are irradiated with an X-ray filter 202 to remove low-energy components harmful to the human body, and after the irradiation area is limited by a collimator 203, the X-ray is irradiated on a subject 209. The X-ray transmitted through the subject 209 is detected by the X-ray detector 206 after scattered radiation is removed by the X-ray grid 205, and is converted into an electric signal. The detected electric signal is sent to the image collecting means 215 via a known slip ring mechanism (not shown). The image collecting means 215 converts the detected electric signal into digital data by a known A / D converter (not shown) and stores the digital data. The image processing means 216 reconstructs the CT image based on the stored digital data, and displays the result on the image display means 217.

FIG. 3 shows an example of an inverter type X-ray high voltage device in which an X-ray tube is connected to a load of the power converter of the present embodiment.

The inverter type X-ray high-voltage device is composed of a voltage step-up converter (301) connected to the commercial voltage, a capacitor (302) connected to the boost converter (301), and a resistor (303) connected to the capacitor (302). , A high voltage transformer 305 connected to the inverter 304, a high voltage rectifier 306 connected to the high voltage transformer 305, and a high voltage rectifier 306 connected to the resistor 303. A tube voltage detector 307 and an X-ray tube 308, a converter control unit 309 connected to the boost converter 301, an inverter control unit 311 connected to the inverter 304, a capacitor connected to the capacitor 302 and the inverter control unit 311 It has a digital control circuit 312 including a deterioration monitoring unit 310, and an operation unit 313 connected to the digital control circuit 312.

Next, the functions of the above components will be briefly described. Boost converter

301 is a high power factor converter with a boost function using an IGBT (Insulated Gate Bipolar Transistor) which is a power module. This step-up converter 301 rectifies a 50 Hz or 60 Hz commercial three-phase AC power supply voltage by a PWM (Pulse Width Modulation) operation, and substantially controls the advance or delay of the phase voltage and phase current. By setting it to zero, the power factor is almost 1. The boost converter 301 operates as a full-wave rectifier circuit when the operation of the IGBT is stopped, and the DC output voltage at the time of the full-wave rectification becomes twice the value of the AC input voltage.

[0020] The capacitor 302 is connected in series to secure a withstand voltage twice as high as the AC input voltage.

There are two. The resistor 303 is provided to equalize the voltage distribution of the two capacitors 302 connected in series. Inverter 304 is boost converter 301 The DC voltage output from the DC-DC converter is converted into a high-frequency AC voltage. The inverter 304 also has a function of controlling a voltage (tube voltage) applied to the X-ray tube 308 as a load.

The high-voltage transformer 305 has its primary winding connected to the output side of the inverter 302, and boosts the AC voltage converted by the inverter 304. The high-voltage rectifier 306 converts the high-frequency high voltage from the secondary winding of the high-voltage transformer 305 into a DC high voltage, the output end of which is connected to the X-ray tube 308, and the DC high voltage is connected to the X-ray tube 8. Is applied to The tube voltage detector 307 detects a voltage applied to the X-ray tube 308. The X-ray tube 308 is supplied with a DC high voltage from the rectifier 306 to generate X-rays.

The digital control circuit 312 has a converter control unit 309, a capacitor deterioration monitoring unit 310, and an inverter control unit 311.

Converter control section 309 performs switch control on the IGBT in boost converter 301. The capacitor deterioration monitoring unit 310 monitors the deterioration of the capacitor 302. The inverter control unit 311 has a function of detecting the phase current and the output voltage of the boost converter 301, detecting the tube voltage with the tube voltage detector 307, and making it match the target value.

The operation unit 313 sets operation conditions such as a tube voltage, a tube current, and an X-ray irradiation time, and commands for the digital control circuit 312. It also has a function to monitor the state of the power converter.

Next, the capacitor deterioration monitoring section 310, which is a main part of the present invention, is configured as follows.

When the power converter operates the boost converter 301 in its initial state (at the time of shipment or installation, etc.) and then stops its operation (non-boost state), the capacitor 302 is discharged via the resistor 303. Then, the state shifts to the full-wave rectification state. The capacitor deterioration monitoring unit 310 detects a characteristic of a voltage drop across the capacitor 302 during a period in which the capacitor 302 shifts from discharging to full-wave rectification. Further, capacitor deterioration monitoring section 310 stores the detected voltage drop characteristic as a voltage drop characteristic in an initial state in a memory in capacitor deterioration diagnosis section 310.

As a storage method at this time, as shown in FIG. 4, the value of the voltage drop after a predetermined time from the stop of the boosting operation of boost converter 301 is stored. Further, as another storage method, as shown in FIG. 5, the voltage drops from the stop of the boost operation of the boost converter 301 until the voltage reaches a predetermined voltage value. The elapsed time at is stored. These storage methods may be used alone or in combination.

Next, when the power conversion device is used (here, also simply referred to as “when the device is used”), the capacitor deterioration diagnosis unit 310 starts full-wave rectification from when the boosting operation of the boost converter 301 is stopped. The voltage drop characteristics of the capacitor 302 during the period before transition to the state are detected as the voltage drop characteristics during use. The capacitor deterioration diagnosis unit 310 compares the voltage drop characteristics in the initial state stored in the memory with the voltage drop characteristics during use of the device, and if the comparison result at least satisfies the following items, the capacitor 302 is deteriorated. Judge as having done.

(1) When the voltage drop rate when using the device increases from the initial state to a predetermined value

(2) When the voltage drop rate during use of the device increases at a predetermined rate for each measurement during use

The capacitor deterioration monitoring unit 310 generates a warning signal when it is determined that the capacitor 302 has deteriorated. The generated warning signal is transmitted to the warning display unit 314 of the operation unit 313.

When a warning signal is received from capacitor deterioration monitoring section 310, warning display section 314 notifies the operator of the warning. Here, the notification means that the operator of the medical image diagnostic apparatus is notified through the five senses, such as visual information such as display, auditory information such as voice, tactile information by vibration such as a vibrator function of a mobile phone, and the like.

The notification at this time is performed on the following items alone or in combination.

(1) The warning display section 314 displays a direct message that "deterioration of the capacitor is recognized". In addition, the warning display unit 314 may be provided with a separate voice generator and a speaker to generate the message by voice. Further, the warning display unit 314 may vibrate the housing of the warning display unit 314 together with the display of the message or the generation of sound.

(2) The warning display section 314 displays an indirect message "Please contact the service center within one week with this warning code" together with the warning code. In addition, the warning display unit 314 may be provided with a separate voice generator and a speaker, and generate the message by voice. Further, the warning display unit 314 may vibrate the housing of the warning display unit 314 together with the display of the message or the generation of sound. (3) The warning display section 314 turns on a warning lamp. If this warning lamp imitates an electrolytic capacitor, it is easy to understand intuitively.

(4) The warning display unit 314 transmits the deterioration information of the capacitor 302 to the network 315 via an interface capable of transmitting to the network 315 such as the Internet, regardless of the display or non-display of (1)-(3) above. Similarly, a receiving terminal 316 (such as a personal computer) installed in a service center connected to the network 315 receives the deterioration information of the capacitor 302 transmitted by the transmitting means, and You may let us know the situation.

With the circuit configuration described above, it is not necessary to provide a resistor and a switch connected in parallel to the capacitor.

Thus, since the converter circuit is a step-up converter, a high withstand voltage switch proportional to the voltage applied to the capacitor is not required, which can contribute to the miniaturization of the device.

As described above, when the present embodiment is used for an inverter-type X-ray high-voltage device to which a boost type high power factor converter is applied, the power of the capacitor in an initial state that requires no special components is required. Since the drop characteristic is used as a criterion for the deterioration determination, it is possible to perform the deterioration determination of the capacitor with high accuracy for each capacitor.

This makes it possible to avoid a failure that occurs during the operation of the power converter.

[0029] In the circuit configuration described above, an example in which the converter circuit is a boost converter has been described. However, the converter may not be limited to a boost converter when implementing the present invention.

This is because the point of the present invention is to eliminate the influence on the power converter due to the deterioration of the capacitor, so that the frequency of diagnosis of deterioration of the capacitor becomes a problem, and the type of converter is not limited to the boost type. .

Example 2

Next, the present embodiment describes a case where the load of the power converter is a gradient coil of the MRI apparatus.

FIG. 6 is a diagram showing an overall outline of an MRI apparatus to which the present invention is applied. This MRI device The static magnetic field magnet 601 that generates a uniform static magnetic field in the space where the subject 612 is placed, the gradient magnetic field coil 602 that forms a magnetic field gradient in this space, and the nuclei of the atoms that make up the tissue of the subject 612 An irradiation coil 604 for irradiating a high-frequency magnetic field having the same frequency as the resonance frequency, and a receiving coil 606 for receiving an NMR signal generated from the subject 612. The gradient magnetic field coil 602 is connected to a gradient magnetic field power supply 603, and the irradiation coil 604 is connected to a transmission system 605 composed of an oscillator, a modulator, an amplifier, and the like that oscillates a high frequency having the same frequency as the resonance frequency. The receiving coil 606 is connected to a receiving system 607 including an amplifier, a phase detector, an A / D converter, and the like.

The gradient magnetic field power supply 603, the transmission system 605, and the reception system 607 are connected to the CPU 608.

The CPU 608 controls the operations of the gradient magnetic field power supply 603, the transmission system 605, and the reception system 607, performs signal processing on the NMR signal received by the reception system 607, and performs operations such as image reconstruction.

The CPU 608 includes a storage device 611 such as a ROM and a RAM for storing a program for the control and a program for the calculation, a calculation result and the like, a display 609 for displaying an image and the like as a calculation result, and a device. An operation console 610 is provided for inputting commands for operation, imaging conditions, and the like.

Specifically, for example, an imaging sequence such as a gradient echo method is incorporated as a program in advance, and a desired imaging sequence can be selected on console 610. Further, as parameters of the imaging conditions, for example, the slice thickness / slice encoding number, imaging field of view (FOV), frequency band, asymmetric measurement rate (AMI), sampling number, etc. are set for the slice. When the imaging sequence and imaging conditions are set by console 610, imaging is performed according to the imaging sequence.

[0034] In recent years, high-speed imaging techniques such as an echo brain imaging method have been developed for the MRI apparatus. Power conversion devices are required to increase the output current of a power supply for generating a magnetic field and to shorten the rise time of the power supply in accordance with the high-speed imaging technique, and there is a trend to increase the current and the voltage. In order to improve the output current change rate of the magnetic field generation power supply, the power converter needs to increase and stabilize the input voltage to the gradient coil. Therefore, as a switching power supply for generating a magnetic field for generating a static magnetic field or a gradient magnetic field, a stabilized power supply for an MRI apparatus having a voltage-type AC / DC converter has been used. FIG. 7 is a block diagram showing an example of a power supply device for generating a gradient magnetic field in the MRI apparatus of FIG. 6. A power supply device 701 for generating a gradient magnetic field is a power supply type AC / DC converter connected to a commercial power supply 702. And a capacitor 704 connected to the power supply type AC / DC converter 703, a resistor 705 and a current amplifier 706 connected to the capacitor 704.

The power supply type AC / DC converter 703 converts an AC current of the commercial power supply 702 into a DC current. The capacitor 704 smoothes the DC current converted by the AC / DC converter 703. The resistor 705 is connected in parallel with the capacitor 704 to enable the voltage detector 720 to detect the voltage. The current amplifier 706 amplifies the DC current smoothed by the capacitor 704. The gradient coil 707 is driven by the current amplified by the current amplifier 706.

[0036] The AC / DC converter 703 used here includes a rear turtle 708-710 connected to the commercial power supply 702, a flywheel diode fully connected to the rear turtle 708-710, and a switching connected in parallel to the flywheel diode. IGBT711-716 as elements.

The output voltage of such a voltage type AC / DC converter 703 is controlled by a control circuit 717. That is, the control circuit 717 determines the input current to the voltage-type AC / DC converter 703 detected by the current detectors 718 and 719, the voltage of the capacitor 704 detected by the voltage detection means 720, and the voltage input from the outside. The output voltage is feedback-controlled based on the command value. In this control, the smoothing capacitor 704 is charged through the rear turtle 708-710 and the switching elements 711-716 connected to the commercial power supply, and the charging voltage is changed to a high voltage by changing the duty ratio of the switching elements 711-716. Controlling. The output current of the current amplifier 706 is feedback-controlled by the control circuit 721. The control circuit 717 calculates the amplification factor of the current amplifier 706 based on the current value detected by the current detector 722 and the specified current value input from the outside, and controls the current amplifier 706 based on the calculated amplification factor. are doing.

The voltage detecting means 720 detects the voltage of the capacitor 704 via the resistor 705 at any time. The capacitor deterioration monitoring unit 723 is provided in the control circuit 717, and discharges the capacitor 704 from the boosted state of the power supply AC / DC converter 703 and shifts the capacity to the non-boosted state. Measure the voltage drop characteristics when both ends are used. Further, similarly to the first embodiment, the capacitor deterioration monitoring unit 723 compares the voltage drop characteristics in the initial state of the power supply for the MRI apparatus and the voltage drop characteristics during the use, which are stored in the memory of the capacitor deterioration monitoring unit 723 in advance. Compare. Then, the capacitor deterioration monitoring unit 723 determines that the capacitor 704 has deteriorated when it is recognized that the voltage drop characteristic during use is shorter than the predetermined value in the voltage drop time from the initial state. The operation unit 724 of the MRI apparatus reports the deterioration state of the capacitor 704 determined by the capacitor deterioration monitoring unit 723. The notification method at this time is performed by the method described in the first embodiment.

As described above, when the present invention is applied to the power supply device for MRI, a failure due to deterioration of the capacitor can be prevented beforehand, so that high reliability as a stable power supply to be supplied to the MRI device can be secured.

[0040] In each of the above-described embodiments, the power in which a three-phase boost converter is used is not limited to this. The present invention is not limited to this and can be applied to a power converter using a single-phase boost converter. Needless to say.

As described above, a plurality of embodiments of the present invention have been described. However, the technical contents for realizing the technical idea described in the claims without being limited to the above-described embodiments are all limited. It is included in the present invention.

Industrial applicability

[0042] The power conversion device of the present invention can prevent a failure due to deterioration of the capacitor beforehand, and thus can secure high reliability as a stable power supply to be supplied to the medical image diagnostic apparatus.

Claims

The scope of the claims

[1] a converter for rectifying commercial AC voltage to DC voltage,

A capacitor for smoothing the DC voltage rectified by the converter,

An inverter for converting the DC voltage smoothed by the capacitor into an AC voltage having a predetermined frequency;

Measuring means for measuring the charge / discharge characteristics of the capacitor each time the power conversion device is used; measuring the charge / discharge characteristics of the capacitor in an initial state in advance by the measuring means; Storage means for storing charge / discharge characteristics; comparison means for comparing the charge / discharge characteristics of the capacitor measured by the measuring means for each use with the charge / discharge characteristics of the capacitor in the initial state stored by the storage means;

Capacitor deterioration determining means for determining a deterioration state of the capacitor based on a result compared by the comparing means;

Notifying means for notifying the deterioration state of the capacitor determined by the capacitor deterioration determining means;

A power conversion device comprising:

2. The power converter according to claim 1, wherein the measuring unit measures a voltage drop characteristic of both ends of the capacitor as a charge / discharge characteristic of the capacitor from a charge state to a discharge state of the capacitor. .

3. The power conversion device according to claim 1, wherein the storage unit stores charge / discharge characteristics of the capacitor in an initial state measured by the measurement unit.

[4] The claim 3 wherein the converter is a step-up converter, and the storage means stores a value of a voltage drop after a predetermined time after stopping the step-up operation of the step-up converter. The power converter according to any one of the preceding claims.

[5] The converter is a boost converter, and the storage means stores an elapsed time from when the boost operation of the boost converter is stopped to when the voltage drops to a predetermined voltage value. The power converter according to claim 3, wherein

[6] The determination means determines that the capacitor has deteriorated when the result of the comparison means indicates that the voltage drop rate during use of the power converter has increased from an initial state to a predetermined value. The power converter according to any one of claims 2 to 5.

[7] The determining means determines that the capacitor is degraded when the result of the comparing means indicates that the voltage drop rate during use of the power converter increases at a predetermined rate every measurement during use. The power converter according to any one of claims 2 to 5, characterized in that:

[8] The electric power according to [4], wherein the notifying means displays the deterioration information on a monitor when the judging means judges that the capacitor has deteriorated. Conversion device.

9. The power converter according to claim 8, wherein the notifying unit displays the countermeasure information together with the deterioration information on a monitor.

10. The power conversion device according to claim 8, wherein the notification unit displays the deterioration information on a monitor by schematically illustrating a shape of the capacitor.

[11] The electric power according to any one of [17] to [17], wherein the notifying unit notifies the deterioration information by voice when the determining unit determines that the capacitor has deteriorated. Conversion device.

[12] The electric power according to any one of [17] to [17], wherein the notifying means, when the determining means determines that the capacitor has deteriorated, notifies the deterioration information by vibration. Conversion device.

[13] The notifying unit is a transmitting unit that transmits the deterioration information of the capacitor to a network, and is installed at a service center in a location different from the transmitting unit and receives the deterioration information of the capacitor transmitted by the transmitting unit. The power converter according to any one of claims 17 to 17, further comprising a receiving unit, and a unit configured to display deterioration information of the capacitor received by the receiving unit.

[14] A power converter according to any one of [11] to [13], and a high-voltage transformer connected to an output side of an inverter of the power converter and configured to boost an output voltage of the inverter. A high-voltage rectifier that converts the output of the high-voltage transformer into a DC high-voltage, an X-ray tube that is connected to the output of the high-voltage rectifier and is a load, and sets the X-ray output conditions of this X-ray tube An inverter X-ray high-voltage device comprising: the operating means.

[15] The inverter X-ray high-voltage device according to claim 14, and a high voltage of the inverter X-ray high-voltage device is supplied to generate X-rays and irradiate the generated X-rays to a subject. An X-ray source, an image receiving unit arranged to face the X-ray source and receiving transmitted X-rays of the subject, a display unit for displaying an X-ray image received by the image receiving unit, the X-ray source, An X-ray fluoroscopic apparatus, comprising: a console for inputting a control amount for controlling the bed and the image receiving unit.

[16] The inverter X-ray high-voltage device according to claim 14, and a high voltage of the inverter X-ray high-voltage device is supplied to generate X-rays, and the generated X-rays are irradiated to a subject. An X-ray source, an X-ray detector arranged opposite to the X-ray source with the subject interposed therebetween and detecting transmitted X-rays of the subject as projection data, the X-ray detector and the X-ray source A rotating plate that supports and rotates the image, an image processing unit that reconstructs a tomographic image of the subject from the projection data obtained by rotating the rotating plate from multiple directions, X-ray CT apparatus comprising: image display means for displaying a reconstructed tomographic image of the subject.

[17] A static magnetic field magnet that generates a uniform static magnetic field in the space where the subject is placed, a gradient magnetic field coil that forms a magnetic field gradient in this space, and nuclei of the atoms that make up the tissue of the subject An irradiation coil for irradiating a high-frequency magnetic field having the same frequency as the resonance frequency, a receiving coil for receiving an NMR signal generated from the subject, and a signal processing of the NMR signal received by the receiving coil to obtain a slice of the subject An MRI apparatus comprising: an image processing means for performing image reconstruction calculation of an image; and an image display means for displaying a tomographic image of the subject reconstructed by the image processing means. 14. An MRI apparatus, wherein the gradient magnetic field power supply supplied to the gradient magnetic field coil is the power conversion device according to claim 1, wherein the power is a power conversion apparatus.