JPH10125493A - Inverter type x-ray high voltage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize each part of a converter circuit and an inverter circuit, and to reduce the location space for inverter type X-ray high voltage device by forming a converter circuit for converting the alternating current voltage to the direct current voltage and an inverter circuit for converting the direct current to the high frequency alternating current with the semi-conductor three- phase module. SOLUTION: A semi-conductor three-phase module 4 of this inverter type X-ray high voltage device works as a converter for rectifying the alternating current voltage from a single phase alternating current power source 1 to the direct current voltage and as an inverter for converting the direct current voltage to the high frequency direct current. Conversion from the alternating current voltage to the direct current voltage is performed by a voltage doubler circuit, which is formed of diodes 241, 242 and smoothening capacitors 31, 32, and conversion from the direct current voltage to the high frequency alternating current is performed by a full-bridge type inverter circuit, which is formed of switching elements 143-146 and diodes 243-246 reversely connected in parallel with each element 143-146.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for converting an AC power source into a direct current, converting the direct current into a high-frequency alternating current using an inverter circuit, and boosting and rectifying the output voltage of the AC power.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter type X-ray high voltage device for generating X-rays by applying a current to a tube.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, an inverter type X-ray high voltage apparatus of this type converts an AC voltage from a commercial 200 V single-phase AC power supply 1 'to a DC voltage by a converter 2' composed of a thyristor. Into a smoothing capacitor 3 '
And input to a full-bridge inverter circuit 4 'using an IGBT (insulated gate bipolar transistor). This inverter circuit 4 'is disclosed in
As described in Japanese Patent Publication No. 90556, the phase difference and the frequency of the inverter circuit 4 'are controlled by utilizing the resonance phenomenon between the resonance capacitor 5' and the leakage inductance and stray capacitance of the high-voltage transformer 6 '. By doing so, a high voltage is applied to the X-ray tube 8 'as a load. The AC voltage from the inverter circuit 4' is boosted by the high-voltage transformer 6 ', and the AC voltage is boosted by the rectifier circuit 7' (second Rectifier circuit) to convert the current into a direct current and apply it to the X-ray tube 8 '.

As shown in FIG. 5, the converter 2 'comprises four diodes 11', 12 ', 13',
A full-wave rectifier circuit is formed by a semiconductor module of a bridge circuit by 14 ', the voltage of the single-phase AC power supply 1' is rectified by the full-wave rectifier circuit, and the rectified voltage is smoothed by a smoothing capacitor 15 '. Input voltage.

As shown in FIG. 6, a full-wave rectifier circuit is constituted by a semiconductor module of a bridge circuit comprising six diodes 21 ', 22', 23 ', 24', 25 ', 26', The voltage of the power supply 20 'is rectified by the full-wave rectifier circuit, and the rectified voltage is smoothed by the smoothing capacitor 27' to obtain the input voltage of the inverter circuit 4 '.

FIG. 7 shows an example of a circuit for increasing the input voltage to the inverter circuit 4 'to twice that of the example shown in FIG. 4. The semiconductor module includes diodes 31' and 32 'of the converter 2' and a smoothing capacitor 33 '. , 34 'constitute a voltage doubler rectifier circuit. The voltage of the single-phase AC power supply 30' is doubled and rectified by the voltage doubler rectifier circuit, and this is used as the input voltage of the inverter circuit 4 '.

FIG. 8 shows a circuit example in which the input voltage of the inverter circuit 4 'is increased from 0 V to twice the example shown in FIG. 5 in the example shown in FIG. 5, and the thyristor 4 of the converter 2'
A voltage doubler rectifier circuit is constituted by the semiconductor modules 1 'and 42' and the smoothing capacitors 43 'and 44', and the voltage of the single-phase AC power supply 40 'is boosted and rectified from 0 V to twice by the voltage doubler rectifier circuit. , Which is the input voltage of the inverter circuit 4 '.

As described above, in the conventional inverter type X-ray high voltage device, only the diode portion or the thyristor portion of the converter 2 'is modularized to reduce the size.

[0008]

SUMMARY OF THE INVENTION As a result of studying the above prior art, the present inventor has found the following problems.

In the prior art, the converter circuit for converting an AC voltage to a DC and the inverter circuit for converting the DC voltage to a high frequency are constituted by separate modules. There was a limit in reducing the

An object of the present invention is to provide a technique capable of reducing an installation space for an inverter type X-ray high voltage device.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0012]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

An AC power supply, a first capacitor having a negative electrode connected to the AC power supply, a second capacitor having a positive electrode connected to the negative electrode of the first capacitor, and the first capacitor of the AC power supply A semiconductor three-phase module, which is connected to a terminal to which the second capacitor is not connected, and includes a converter circuit for converting an AC voltage to DC and an inverter circuit for converting the DC to high-frequency AC; A high-voltage transformer that boosts the output voltage,
A rectifier circuit for rectifying the output of the high-voltage transformer, and an inverter-type X-ray high-voltage device for generating an X-ray by applying an output voltage of the rectifier circuit to an X-ray tube.

According to the above-described means, the converter circuit and the inverter circuit for converting the AC voltage to DC and the inverter circuit for converting the DC to high-frequency AC are constituted by the semiconductor three-phase module. Since the size is reduced, the installation space of the inverter type X-ray high voltage device can be reduced.

When the rated current is large, as in the case of an inverter type X-ray high-voltage device, the proportion of the semiconductor module in the entire device cannot be neglected.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In all the drawings for describing the embodiments, those having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.

(Embodiment 1) FIG. 1 shows Embodiment 1 of the present invention.
1 is a circuit configuration diagram showing a schematic configuration of an inverter type X-ray high voltage device of the present invention, where 1 is a commercial 200 V single-phase AC power supply
Reference numeral 32 denotes a smoothing capacitor, 4 denotes a semiconductor three-phase module circuit using an IGBT, 5 denotes a resonance capacitor, 6 denotes a high-voltage transformer, 7 denotes a high-voltage rectifier, and 8 denotes an X-ray tube.

The semiconductor three-phase module circuit 4 is shown in FIG.
As shown in (1), the converter functions as a converter for rectifying the AC voltage from the single-phase AC power supply 1 to a DC voltage and an inverter for converting the DC voltage to a high-frequency AC. An extinguishing switching element, here an insulated gate bipolar transistor (I
Six switching elements 141 to 14 made of GBT)
6 and diodes 241 to 246 connected in anti-parallel to the respective switching elements 141 to 146.

The conversion from the AC voltage to the DC voltage is made up of diodes 241 and 242 and smoothing capacitors 31 and 32, and is performed by the same voltage multiplier circuit as in FIG.

The conversion of this DC voltage to a high frequency is as follows:
The switching is performed by a full-bridge inverter circuit including switching elements 143 to 146 and diodes 243 to 246 connected in anti-parallel to the switching elements 143 to 146.

If the switching elements 141 and 142 are kept off during the positive half cycle of the AC power supply 1, the diode 242 conducts, and the AC power supply 1 → the capacitor 32
A current flows in a circuit of → diode 242 → AC power supply 1, and energy is stored in capacitor 32. During the negative half cycle of the AC power supply 1, the switching element 14
1, 142 is always off, so that the diode 24
1 conducts, a current flows in a circuit of AC power supply 1 → diode 241 → capacitor 31 → AC power supply 1, and energy is stored in the capacitor 31. By repeating the operation between the positive half cycle and the negative half cycle of the AC power supply 1 in this manner, the voltage between the positive electrode of the smoothing capacitor 31 and the negative electrode of the smoothing capacitor 32 is about twice the peak value of the AC power supply 1. The voltage is charged.

The inverter circuit receives the DC voltage obtained as described above, converts it into an AC voltage, and controls the power supplied to the X-ray tube 8 by utilizing the resonance phenomenon. The four switching elements 143 to 146 made of IGBTs are combined to form a full bridge type, and each of the switching elements 143 to 146 is formed.
6, diodes 243 to 246 are connected in anti-parallel.

FIG. 2 is a circuit diagram showing a six-element type circuit configuration of an example of the semiconductor three-phase module circuit 4 using the IGBT. The vertical length is 107 mm and the horizontal length is 102 m.
m. In FIG. 2, N, P, U, V, and W are terminals.

The capacitor 5 is one of the resonance elements for generating a resonance current by the output voltage of the three-phase module 4. The high voltage transformer 6 has its primary winding connected in series with the capacitor 5, causes resonance with the capacitor 5 and the leakage inductance, and boosts its resonance output.

The second rectifier circuit 7 includes the high-voltage transformer 6
, And converts the output AC voltage to DC. The output voltage of the second rectifier circuit 7 is applied to the X-ray tube 8 to generate X-rays.

(Embodiment 2) FIG. 3 shows Embodiment 2 of the present invention.
1 is a circuit configuration diagram showing a schematic configuration of an inverter type X-ray high-voltage device according to an embodiment of the present invention, in which a converter circuit in a semiconductor three-phase module circuit 4 is a boost type. In FIG.
2 is a rectifier diode, 23 is an AC input reactor,
31 is a smoothing capacitor.

The means for converting an AC voltage into a DC voltage in the inverter type X-ray high voltage apparatus of the second embodiment is constituted by diodes 241 and 242 and a smoothing capacitor 31, and is performed by the same voltage doubler circuit as in FIG.

The conversion of the DC voltage into a high frequency is
The switching is performed by a full-bridge inverter circuit including switching elements 143 to 146 and diodes 243 to 246 connected in anti-parallel to the switching elements 143 to 146.

If the switching elements 141 and 142 are always turned off during the positive half cycle of the AC power supply 1, the diode 242 conducts, and the AC power supply 1 → the capacitor 32
A current flows in a circuit of → diode 242 → AC power supply 1, and energy is stored in capacitor 32. During the negative half cycle of the AC power supply 1, the switching element 14
1, 142 is always off, so that the diode 241
Is conducted, a current flows in a circuit of AC power supply 1 → diode 241 → capacitor 31 → AC power supply 1, and energy is stored in the capacitor 31. By repeating the operation between the positive half cycle and the negative half cycle of the AC power supply 1 in this manner, the voltage between the positive electrode of the smoothing capacitor 31 and the negative electrode of the smoothing capacitor 32 is about twice the peak value of the AC power supply 1. The voltage is charged.

During the negative half cycle of the AC power supply 1, the same operation as described above is performed by the switching element 142 and the diode 22, and the smoothing capacitor 3 is charged with a voltage equal to or higher than the peak value of the AC power supply 1. Can be boosted above the AC power supply voltage.

As can be seen from the above description, according to the first and second embodiments, the converter circuit for converting the AC voltage to DC and the inverter circuit for converting the DC to high-frequency AC are constituted by the semiconductor three-phase module 4. By doing
Since the size of the converter circuit and the inverter circuit is reduced, the installation space for the inverter type X-ray high voltage device can be reduced.

When the rated current is large, as in the case of an X-ray high-voltage device, the size of the semiconductor module 4 in the entire device cannot be ignored, so that downsizing by one module is highly effective.

As described above, the invention made by the present inventor is:
Although specifically described based on the embodiment of the invention, the present invention is not limited to the embodiment of the invention,
Of course, various changes can be made without departing from the scope of the invention.

[0035]

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

Since the converter circuit for converting the AC voltage to DC and the inverter circuit for converting the DC to high-frequency AC are constituted by semiconductor three-phase modules, the converter circuit and the inverter circuit can be reduced in size. The installation space for the X-ray high voltage device can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a schematic configuration of an inverter type X-ray high voltage device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a six-element type circuit configuration as an example of a semiconductor three-phase module circuit using the IGBT of the first embodiment.

FIG. 3 is a circuit diagram illustrating a schematic configuration of an inverter type X-ray high voltage device according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a schematic configuration of a conventional inverter type X-ray high voltage device.

FIG. 5 is a circuit diagram showing a first example of a conventional converter.

FIG. 6 is a circuit diagram showing a first example of a conventional converter.

FIG. 7 is a circuit diagram showing a first example of a conventional converter.

FIG. 8 is a circuit diagram showing a first example of a conventional converter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single-phase commercial power supply of commercial 200V 30, 31 Smoothing capacitor 4 Semiconductor three-phase module circuit 5 Resonant capacitor 6 High voltage transformer 7 High voltage rectifier 8 X-ray tube 141-146 Switching element 241-246 Diode N, P, U , V, W terminals

Claims (1)

[Claims] An AC power supply; a first capacitor having a negative electrode connected to the AC power supply; a second capacitor having a positive electrode connected to the negative electrode of the first capacitor; A three-phase semiconductor module comprising a converter circuit for converting an AC voltage to a direct current and an inverter circuit for converting the direct current to a high-frequency alternating current. A high-voltage transformer for boosting the output voltage of the module, a rectifier circuit for rectifying the output of the high-voltage transformer, and applying an output voltage of the rectifier circuit to an X-ray tube to generate X-rays. Inverter type X-ray high voltage device.