JPH042103A - High voltage transformer for inverter type X-ray high voltage equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-voltage transformer for an inverter-type X-ray high-voltage device that is suitable for compactness, weight reduction, and high performance.

[Conventional technology]

In recent years, in order to make medical X-ray high-voltage equipment smaller, lighter, and more efficient, an inverter has been placed on the input side of the high-voltage transformer, and a low-loss iron core has been used for the high-voltage transformer. Inverter-type X-ray high-voltage equipment that increases the input frequency of the high-voltage transformer and increases the operating magnetic flux density is becoming a problem.

-a, such a high-voltage transformer for an inverter-type X-ray high-voltage device is housed in a tank, and the tank is filled with insulating oil as a cooling fluid.

Therefore, the high voltage transformer is cooled by natural convection of the insulating oil and natural air cooling of the tank.

On the other hand, the temperature rise in high-voltage transformers is mainly caused by iron loss, and this iron loss is roughly proportional to the frequency f of the inverter.
Since they are proportional to the square of the operating magnetic flux density B, there is a limit to the values of f and B due to restrictions on the temperature rise of the high voltage transformer core.

By the way, in this type of conventional high-voltage transformer for an inverter-type X-ray high-voltage device, the temperature rise in the portion of the iron core where the winding is present (hereinafter referred to as the leg portion) is particularly large. (1) Conventionally, the legs of a high-voltage transformer core include, in order from the inside, a primary winding frame, a primary winding, a secondary winding frame, and a secondary winding. Since the heat dissipation efficiency of the yoke portion was lower than that of the portion where no winding of the iron core was present (hereinafter referred to as the yoke portion), the temperature rise in the leg portion was particularly large.

(2) Furthermore, in the high voltage transformer of (1) above, a wedge for fixing the primary winding frame is provided between the core (leg) and the primary winding. Similarly, in conventional high-voltage transformers in which wedges for fixing the secondary winding frame are inserted between the legs and the frame, the heat dissipation efficiency of the legs is lower than that of the yoke of the iron core. The temperature rise in the legs was especially large.

(3) Conventionally, cut cores have been used for high voltage transformer cores due to manufacturing considerations, and the cut portions have been provided in the axially central portions of the legs of the high voltage transformer cores. When the high-voltage transformer is in operation, leakage magnetic flux is generated in the core cut portion, and heat generation due to eddy current loss caused by this causes a temperature rise in the core cut portion to be larger than that in the yoke portion. In addition, the legs of the high-voltage transformer core have 1
There is a secondary winding frame, a primary winding, a secondary winding frame, and a secondary winding, so the heat dissipation efficiency of the legs is lower than that of the yoke, so the temperature rise in the legs is particularly high. It got bigger.

[Problem to be solved by the invention]

As described above, in the conventional inverter type high voltage transformer for X-ray high voltage equipment, the temperature rise in the leg portions of the iron core is particularly large.

Here, the operating magnetic flux density B at the inverter frequency is:
Settings must be made so that the temperature rise in the part of the iron core where the temperature rise is greatest does not exceed a certain standard. For this reason, in the past, although there was a margin in terms of temperature for the yoke part, the above f and B had to be set small,
This poses a problem in that it impedes efforts to make the high-voltage transformer smaller and lighter and to improve the performance of the X-ray high-voltage device. Also, f
There is also the problem that having to set a relatively small value may cause noise generation, which may cause discomfort to the subject and the operator of the apparatus.

The purpose of the present invention is to suppress the temperature rise of the core legs with a simple configuration, thereby increasing the operating magnetic flux density B at the inverter frequency, making the high voltage transformer smaller and lighter, and Since the inverter frequency f can be increased, the ripple of the tube voltage waveform can be further reduced.
As an XIl high voltage device, the performance can be further improved, especially,
To provide a high-voltage transformer for an inverter-type X-ray high-voltage device, which can eliminate unpleasant noises by increasing the inverter frequency f to an inaudible range near 20 kHz, and eliminate discomfort given to a subject and an operator of the device. It is in.

[Means to solve the problem]

(1) The above purpose is to move the primary winding frame, the primary winding, the secondary winding frame, and the
In a high-voltage transformer for an inverter-type X-ray high-voltage device in which the secondary winding is laminated in the order of the secondary winding, the secondary winding frame and the secondary winding are each divided into a plurality of parts in the winding axis direction, and 1
This is achieved by providing a plurality of cooling fluid passage holes in the next winding frame.

(2) Further, a primary winding frame, a primary winding, a secondary winding frame, and a secondary winding are laminated in the order of the iron core located at the center toward the outer circumferential side, and the iron core and a wedge for fixing the primary winding frame between the primary winding frames, and a wedge for fixing the secondary winding frame between the secondary winding frame and the secondary windings. In the high-voltage transformer for an inverter-type X-ray high-voltage device, which is sandwiched between the two, the wedge for fixing the primary winding frame is formed of a hollow body through which a cooling fluid can flow. .

(3) Furthermore, a cup 1 ~ iron core is used for the iron core located at the center, and the primary winding frame,
In a high-voltage transformer for an inverter-type X-ray high-voltage device in which a primary winding, a secondary winding frame, and a secondary winding are laminated in this order, the cut core has a cut portion that is connected to the primary winding. This is achieved by positioning the bobbin, the primary winding, the secondary winding bobbin, and the laminated components of the secondary winding in a position where they are not present.

[Effect]

The secondary winding frame and the secondary winding are each divided into a plurality of parts in the axial direction, and the primary winding frame is provided with a passage hole for cooling fluid (insulating oil). In addition, by configuring the wedge for fixing the primary winding frame with a hollow body through which cooling fluid can flow, the flow of cooling fluid is promoted at each of these locations, the cooling effect is promoted, and the core It can suppress the temperature rise in the legs.

In addition, the core cut part of the cut iron core is connected to the primary winding frame, 1
By locating the secondary winding, the secondary winding frame, and the part where the secondary winding does not exist, leakage magnetic flux is generated in the part of the core cup 1, and even if heat is generated due to eddy current loss, the cooling will not be possible. It is possible to suppress the temperature rise in the core legs.

Here, the values of the inverter frequency f and the operating magnetic flux density B are:
It is determined from the constraint on the temperature rise of the part of the high voltage transformer core where the temperature rise is the greatest.

The temperature rise ΔT of the iron core is approximately expressed as in the following equation (1).

Δ'l'ccαXfXB2 ・・・・・・・・・ (1
) However, α is a constant determined by the material of the core, and a low-loss core has a small value.

Also, the cross-sectional area S of the iron core is expressed as the following formula (2): 3ocl/'(fXB)
2) According to the present invention, since it is possible to suppress the temperature rise of the leg portion of the iron core, the values of f and B can be increased to reduce the cross-sectional area S of the iron core, which improves the efficiency of high-voltage transformers. Compactness and weight reduction are achieved. In addition, since f can be increased, it is possible to further improve the performance of the X-ray high-voltage device, such as by reducing ripples in tube voltage, and to fully utilize the advantages of using an inverter and a low-loss iron core. Furthermore,
By increasing f to an inaudible range of around 20 kHz, it is possible to eliminate harsh noise and eliminate discomfort for the subject and the operator of the apparatus.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 and FIG. 2 each show an inverter type X according to the present invention.
1 is a diagram illustrating an embodiment of a high voltage transformer for line high voltage equipment;
The figure is a longitudinal cross-sectional view, and FIG. 2 is a cross-sectional view. In these FIGS. 1 and 2, 1 is an iron core. 2.3.4 and 5 are a primary winding frame, a primary winding (low voltage winding), which are stacked in order from the iron core 1 toward the outer circumference, with the iron core 1 as the center;
These are a secondary winding winding frame and a secondary winding (high voltage winding). That is, a primary winding frame 2 is arranged around the outer periphery of the iron core 1, a primary winding 3 is wound around the primary winding frame 2, and a secondary winding 3 is wound around the outer periphery of the primary winding. A secondary winding 5 is wound around a winding frame 4. This secondary winding 5 is wound in several tens of layers in order to obtain high voltage. The above configuration is not particularly different from conventional high voltage transformers of the same type.

In the present invention, the secondary winding frame 4 and the secondary winding 5 are each divided into a plurality of parts in the direction of the winding axis (vertical direction in FIG. 1), in this case, into two parts. Further, the primary winding frame 2 is provided with a plurality of through holes 2a for a cooling fluid, in this case insulating oil. At this time, the material of the primary winding frame 2 and the number and size of the flow holes 2a are selected so as not to impair the strength of the primary winding frame 20.

With this configuration, the flow of insulating oil at the leg portions of the iron core 1 is promoted, heat radiation efficiency is increased, and temperature rise in the leg portions can be suppressed. As a result, it becomes possible to increase the inverter frequency f and the operating magnetic flux density B, and the inverter type X! i A high voltage transformer for high voltage equipment can be made smaller and lighter.

3 and 4 respectively show an inverter type X according to the present invention.
FIG. 3 is a longitudinal cross-sectional view, and FIG. 4 is a cross-sectional view, showing another embodiment of the high-voltage transformer for wire high-voltage equipment. These third
In the figure and FIG. 4, 1 is an iron core. 2, 3. 4 and 5 are primary winding frames and primary windings (low-voltage windings) that are stacked in order from core 1 toward the outer circumference with iron core 1 as the center.
, a secondary winding frame and a secondary winding (high voltage winding), 6 is a wedge for fixing the primary winding frame, and 7 is a wedge for fixing the secondary winding frame. That is, a primary winding frame 2 is arranged around the outer periphery of the iron core 1, a primary winding 3 is wound around the primary winding frame 2, and the primary winding 3 is arranged around the outer periphery of the primary winding 3! A secondary winding M5 is wound around the secondary winding frame 4. This secondary winding 5 is
It is wound in several dozen layers to obtain high pressure. Also,
A wedge 6 for fixing the primary winding frame is provided between the iron core 1 and the primary winding frame 2, and a secondary winding frame is provided between the secondary winding frame 4 and the secondary winding 5. The configuration of zero or more fixing wedges 7 inserted therein is not particularly different from conventional high voltage transformers of the same type. In the present invention, the wedges 6 for fixing the primary winding frame are , consisting of a hollow body through which a cooling fluid, here an insulating oil, can flow. Figures 5 to 7 are enlarged views of the wedge 6. Figure 5 is a front view, Figure 6 is a side view, and Figure 7 is a bottom view. In order to further increase this, the hollow wedge 6 is provided with a plurality of insulating oil passage holes 6a.

At this time, the number and size of the communication holes 6a are selected so as not to impair the strength of the wedge 6.

With this configuration, the flow of insulating oil at the leg portions of the iron core 1 is promoted, heat radiation efficiency is increased, and temperature rise in the leg portions can be suppressed. As a result, it becomes possible to increase the inverter frequency f and the operating magnetic flux density B, and the high voltage transformer for the inverter type X-ray high voltage apparatus can be made smaller and lighter.

FIG. 8 and FIG. 9 each show an inverter type X according to the present invention.
FIG. 8 is a longitudinal cross-sectional view, and FIG. 9 is a cross-sectional view, showing still another embodiment of a high-voltage transformer for a wire high-voltage device. In these FIGS. 8 and 9, 1 is a cut iron core. 2
, 3.4 and 5 are a primary winding frame, a primary winding (low voltage winding), and a secondary winding, which are stacked in order from the cut core 1 toward the outer circumference, with the cut core 1 as the center. Frame and secondary winding (
high voltage winding). That is, a primary winding frame 2 is arranged around the outer periphery of the cut iron core 1, a primary winding 3 is wound around the primary winding frame 2, and a primary winding 3 is wound around the outer periphery of the primary winding 3. A secondary winding 5 is wound around the next winding frame 4. This secondary winding 5
is wound in several tens of layers to obtain high pressure. The above configuration is not particularly different from conventional high voltage transformers of the same type.

In the present invention, the cut iron core 1 has a core cut g1
a or said primary winding frame 2. primary winding [3, secondary winding frame 4
and is positioned at a position where the laminated component portion 8 of the secondary winding 5 does not exist.

By removing the core cut portion 1a, which generates a large amount of heat, from the position where the laminated component 8 of the winding frames 2, 4 and the winding 3.5, which has low heat dissipation efficiency, is located, the temperature rise at the leg portions of the core 1 can be reduced. Can be suppressed. As a result, it becomes possible to increase the operating magnetic flux density B at the inverter frequency, and the high voltage transformer for the inverter type X-ray high voltage apparatus can be made smaller and lighter.

FIG. 10 is a diagram showing an example of an inverter type X-ray high voltage apparatus to which the above-described high voltage transformer of the present invention is applied, and HT in the figure is the high voltage transformer of the present invention. Further, 10 is an AC power supply, 11 is a rectifier circuit that converts the AC power supply 10 into DC, 12 is a smoothing capacitor, 13 is transistors 14 to 17, and diodes 18 to 18 connected in antiparallel to each of these transistors 14 to 17. 21 is a full-bridge inverter, and 22 is a resonant capacitor connected to the primary winding 3 of the high voltage transformer HT.

23 is a full-wave rectifier circuit; 24 is a resistor that detects the voltage (tube voltage) applied between the anode and cathode of the X-ray tube 25;
26 is a voltage controller that compares the tube voltage setting value and the tube voltage detection value detected by the resistor 24 and controls the two so that they match; 27 is a voltage controller that amplifies the output of the voltage controller 26 and transfers it to the inverter 13; This is a base drive circuit that supplies the bases of the transistors 14 to 17.

Next, the operation of the inverter type X-ray high voltage apparatus having the above configuration will be explained.

First, conditions (tube voltage, tube current, and imaging time) for X-rays to be emitted to a subject (not shown) are set.

Among these X-ray conditions, FIG. 10 shows the setting and control of only the tube voltage. When the desired tube voltage is set and the X-ray emission start signal is given, the tube voltage setting signal will cause
Voltage controller 26 provides a signal for controlling inverter 13 to base drive circuit 27 . Base drive circuit 27
amplifies it, and the transistors 14~ of the inverter 13
Output to 17 base. As a result, the inverter 13
starts a switching operation that turns transistors 14, 17 and 1516 on and off alternately at a predetermined period to set the tube voltage, and a current (resonant current) with an oscillation period determined by the capacitor and inductance, which will be described later, flows through the high-voltage transformer. 1
(Flows to T.

Among the capacitors and inductances that determine the vibration period, the capacitor is a stray capacitance that exists between the layers of the resonance capacitor 22 connected in series to the primary winding 3 of the high voltage transformer HT and the secondary winding 5 of the high voltage transformer HT. and the stray capacitance of the high voltage cable (not shown), and the inductance is the leakage inductance of the high voltage transformer HT and the inductance of the wiring.

Within a half period of the predetermined period in which the transistors 14 to 17 are driven, the resonant current first draws an arc of the resonant frequency along the path of the transistor 14 → the resonant capacitor 22 → the primary winding 3 of the high voltage transformer HT → the transistor 17. It flows. After 1/2 of this half period, the resonant current becomes zero,
After that, the diode 21→
It flows through the path of the primary winding 3 of the high voltage transformer HT -> the resonance capacitor 22 -> the diode 18. And transistor 1
4.17 turns off, and in the next half cycle, transistor 15
．． 16 turns on.

Then, in contrast to the above operation, a resonant current similarly flows through the path in which the transistors and diodes are replaced.

An alternating current obtained by subtracting the excitation current of the high voltage transformer HT and the current flowing through the stray capacitance of the secondary winding 5 from the primary current flowing through the primary winding 3 of the high voltage transformer HT is rectified by the rectifier circuit 23, It is smoothed by the stray capacitance of the high voltage cable and applied to the X-ray tube 25. The signal corresponding to the actual tube voltage detected by the tube voltage detection resistor 24 is input to the voltage control circuit 26, and the operating frequency or pulse width of the inverter 13 is adjusted so that the difference between it and the set tube voltage signal becomes zero. A signal is created to control the This signal is applied to the bases of transistors 14-17 via base drive circuit 27. As a result, the operating frequency of the inverter 13 in the next cycle is corrected 5, and the tube voltage is accurately controlled to the set value.

In such a circuit configuration, ripples (pulsations) occur in the tube voltage waveform at the inverter frequency when it is rectified by the rectifier circuit 23, but increasing the inverter frequency f improves performance by reducing this ripple. This means that it becomes possible. Further, by increasing the inverter frequency f to an inaudible frequency of around 20 kHz, noiseless operation can be achieved, thereby eliminating discomfort for the subject and the operator of the apparatus.

〔Effect of the invention〕

According to the present invention, it is possible to suppress the temperature rise of the iron core legs with a simple configuration, and therefore it is possible to increase the operating magnetic flux density B at the inverter frequency.
It can be quantified. By increasing the inverter frequency f, the ripple of the tube voltage waveform is further promoted,
This allows for even higher performance as an X-ray high-voltage device. Particularly, by increasing the inverter frequency f to an inaudible range of around 20 kHz, it is possible to eliminate harsh noise and eliminate discomfort to the subject and the operator of the apparatus.

[Brief explanation of drawings]

FIGS. 1 and 2 are longitudinal cross-sectional views and cross-sectional views showing one embodiment of the high-voltage transformer of the present invention, and FIGS. 3 and 4 are longitudinal cross-sectional views showing other embodiments of the high-voltage transformer of the present invention. and cross-sectional view, 5th
Figures 6 and 7 are enlarged front views, side views, and bottom views of the wedges for fixing the winding frame in Figures 3 and 4, and Figures 8 and 9. The figure is a vertical cross-sectional view and a cross-sectional view showing still another embodiment of the high-voltage transformer of the present invention, and FIG. 10 is a diagram showing an example of an inverter type X-ray high-voltage device to which the high-voltage transformer of the present invention is applied. . 1... Iron core (cut iron core), 1a... Core cut portion, 2... Primary winding frame, 2a... Insulating oil (cooling fluid) flow hole, 3... Primary Winding, 4...Secondary winding frame, 5...Secondary winding, 6...Wedge for fixing the primary winding frame, 6a...Insulating oil (cooling fluid) flow Hole, 7...
Wedge for fixing secondary winding frame, 8... Winding frame 9 winding laminated component, HT... High voltage transformer of the present invention, 10... AC power supply, 11... Rectifier circuit, 12...・Smoothing capacitor, 13... Full bridge inverter, 22...
Resonance capacitor, 23...Full wave rectifier circuit, 25...
-X-ray tube, 26...voltage controller, 27...base drive circuit.

Claims (3)

[Claims] 1. A high voltage for inverter-type X-ray high voltage equipment, which is constructed by stacking the primary winding frame, primary winding, secondary winding frame, and secondary winding in the order of the iron core located at the center toward the outer periphery. In the transformer, the secondary winding frame and the secondary winding are each divided into a plurality of parts in the winding axis direction, and the primary winding frame is provided with a plurality of cooling fluid passage holes. A high voltage transformer for inverter type X-ray high voltage equipment. 2. A primary winding frame, a primary winding, a secondary winding frame, and a secondary winding are laminated in this order from an iron core located at the center toward the outer periphery, and the iron core and the primary winding a wedge for fixing the primary winding frame between the winding frames; a wedge for fixing the secondary winding frame between the secondary winding frame and the secondary windings;
In the high-voltage transformer for an inverter-type X-ray high-voltage device that is sandwiched in each case, the wedge for fixing the primary winding frame is a hollow body through which a cooling fluid can flow. High voltage transformer. 3. A cut iron core is used for the iron core located at the center, and from this iron core toward the outer periphery, the primary winding frame, the primary winding,
In a high-voltage transformer for an inverter-type X-ray high-voltage device in which a secondary winding frame and a secondary winding are laminated in this order, the cut core has a core cut portion that is stacked on the primary winding frame and the primary winding. A high-voltage transformer for an inverter-type X-ray high-voltage device, which is positioned at a position where a winding, a secondary winding frame, and a laminated component of the secondary winding are not present.