JPS6128112A - Three-phase high voltage controller - Google Patents

Abstract

PURPOSE:To simplify the circuit by applying sequentially a voltage given to each three-phase line based on the zero phase detected for each line voltage while applying limitation to the direction so as to prevent overshoot due to transient phenomenon and eliminating the adjusting position. CONSTITUTION:Each line voltage of U-V-W-U is detected by photocouplers 1PC 3PC as an isolated signal and a zero phase timing pulse is formed by a zero phase detection storage circuit 3. When a signal (a) among zero phase timing signals (a)-(f) at a phase of high voltage is given to a gate of a thyristor 1SCR, it is conductive, the anode goes to an L potential, all signal input/output terminals B-F go to L potential, no signals (b)-(f) are generated and only the signal (a) is generated. Thus, the signals (a)-(f) are ORed by an OR gate circuit OR, only the signal (a) appears as the zero phase timing signal of the high voltage applied phase being an input of an image pickup timer circuit 5 and an image pickup switching signal XST is given to the circuit 5 synchronously with the signal (a).

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a three-phase high voltage control device, and particularly to a three-phase high voltage control device that suppresses transient phenomena in a high voltage waveform as much as possible and prevents biased magnetization of the iron core of a high voltage generator. The present invention also relates to a high voltage control device equipped with a three-phase high voltage turning-on mechanism that is easy to adjust.

[Background technology]

In a three-phase X-ray high-voltage control system using a primary side control system, the high voltage application methods have conventionally been: (1) simultaneous application of three phases and a braking resistor applied for a certain period of time in only one phase; 2) There is a method in which a single phase is turned on and one phase of braking resistance is also introduced for a certain period of time, resulting in three-phase operation. Among them, in the former method (1), the resistance value of the braking resistor and the braking time must be changed in detail depending on the X-ray load conditions, so the control circuit is complicated and adjustment is not easy.

Another problem is that a large current must be directly controlled. Also, in the latter method (2), the optimal point for transitioning to three-phase operation is theoretically 90° after the single-phase is turned on, but in reality the stray capacitance of the high voltage system and the impedance of the power supply equipment Adjustment becomes difficult because a slight deviation occurs due to the influence of factors such as The problem is that it is extremely difficult.

Next, as methods for preventing biased magnetization in high voltage generators, there are two methods: applying direct current magnetization in advance before imaging and then applying it in a direction that cancels out the magnetization. There is a method in which the magnet is introduced in a direction that cancels out the magnetization.
The former can almost completely prevent biased magnetization, but this requires a complicated mechanism and an increase in the number of adjustment points.
There is a problem that unnecessary X-rays are emitted. Further, although the latter can simplify the structure, it has the problem that polarized magnetization cannot be completely prevented at a certain imaging time.

[Purpose of the invention]

The purpose of the present invention is to improve high voltage waveform ripple by suppressing overshoot caused by transient phenomena in a three-phase high voltage control device using a primary side control method. The objective is to provide technology that is inexpensive and easy to adjust.

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

[Summary of the Invention] Among the inventions disclosed in this application, a brief outline of typical inventions is as follows.

In other words, in a three-phase electrical high-voltage control device using a primary side control system, the method for preventing overshoot due to transient phenomena is to simplify the circuit configuration by adopting a method of switching on a single phase and then switching to three phases. Each time, while limiting the current flowing through each line, the line voltages U-V, W-U, and V-W are sequentially turned on at zero phase or nearly zero phase to prevent overshoot due to transient phenomena and adjust. It's missing parts.

[Structure of the invention]

Hereinafter, the configuration of the present invention will be explained along with examples.

In addition, in all the figures for explaining the embodiment, parts having the same functions are given the same reference numerals, and repeated explanations thereof will be omitted.

1 to 3 are diagrams for explaining a three-phase X-ray high voltage control device according to an embodiment of the present invention.

Fig. 1 is a circuit diagram showing the schematic configuration of the main circuit of the three-phase X-ray high voltage control device, and Fig. 2 shows the configuration of the three-phase high voltage turning-on control device of the main circuit shown in Fig. 1. The circuit diagram, Figure 3, is
3 is a time chart for explaining the operation of the three-phase high voltage closing control device of FIG. 2. FIG.

In FIGS. 1 to 3, U-V', V-W.

W-U is the line voltage, l is the three-phase power supply, and S+.

S2. S3 is the power switch, 5CR-U, 5CR-V,
SC, R-W, 5CR-X, 5CR-Y and 5CR-Z
is a main circuit switching thyristor, and thyristor 5CR-
Thyristor U and thyristor 5CR-X, thyristor 5CR-V and thyristor 5CR-Y, and thyristor 5CR-W and thyristor 5CR-Z are each connected in antiparallel. 2 is a high voltage generator, IPC to 9PC are photocouplers, 3
is a zero phase detection storage circuit, INT is an inverter for signal inversion, 3A is a differential circuit, IC is a capacitor, IR is a resistor, l
D is a diode, l5CR to SC and RL2 are thyristors, 3B is a delay circuit, vCC is a constant voltage, and A to F are signal input/output terminals.

a to f are zero phase timing signals of high voltage application phase, OR
is an OR gate circuit that inputs the zero-phase timing signals a to f of the high voltage application phase, XST is the photographing opening/closing signal,
4 is an AND gate circuit, 5 is a photographing timer circuit, and 6 is an SCR gate control circuit.

Next, the operation of this embodiment will be explained.

Ite, U-V, V-W in FIGS. 1 to 3.

Each line voltage of W-U is connected to photocouplers IPC, 2PC, 3
It is detected as an isolated signal by a PC, and a zero-phase timing pulse is generated by the zero-phase detection and storage circuit 3. At this time,
Until the shooting opening/closing signal XST comes, thyristor l5
The cathodes of CR to 6SCR are at low potential and are in a conductive state. Now, suppose that the zero-phase timing signal a of the high voltage application phase is sent to the gate of thyristor I5CAR.
CR becomes conductive, and the anode of thyristor l5CR becomes a low potential. Therefore, signal input/output terminals B, C, D, and E are connected through diodes.
, , F are all at low potential, and the zero-phase timing pulses of the high-voltage application phase zero-phase timing signals 0 to f are not generated, and only the high-voltage application phase zero-phase timing signal a is generated. is occurring. Therefore, the logical sum (OR) of the zero-phase timing signals a to f of the high-voltage application phase is taken by the OR gate circuit OR, and this is used as the zero-phase timing signal of the high-voltage application phase that is input to the imaging timer circuit 5. In this case, the zero phase timing signal a of the high voltage application phase
Only the zero-phase timing pulse of will appear,
The photographing opening/closing signal XST is actually transmitted to the photographing timer circuit 5 through this zero phase timing signal a of the high voltage application phase.
This is done in synchronization with the timing pulse of Then, when the photographing timer circuit 5 operates and generates a predetermined photographing time signal, the cathodes of the thyristors 15CR to 6SCR become high potential, and all the thyristors become non-conductive. This thyristor l5CR to 6SC,R is 5
Next, conduction becomes possible after a certain period of time has elapsed (delayed) after the operation of the imaging timer circuit 5 is completed, and then the zero-phase timing signals a to f of the first high voltage application phase are activated. The zero phase timing pulse causes thyristor l5
Any one of CR to 6SCR conducts, and the other five thyristors are kept in a non-conducting state as in the previous example.

Next, the other output of the photographing timer circuit 5 is connected to the inverter I
The signal is inverted by NT and sent to the SCR gate control circuit 6, and the thyristors 7SCR to 1.2SCR become conductive. Now, as in the above example, thyristor l5 is initially
CR is on (ON) L.

Consider the case where only the zero-phase timing signal a is generated. When thyristors 7SCR to 12SCR become conductive, if a zero-phase timing signal of the high voltage application phase is applied to the gate of each thyristor, the thyristors are actually turned on. At this time, the first pulse that comes is the zero-phase timing signal a of the high-voltage application phase, and this zero-phase timing signal a of the high-voltage application phase is applied to the thyristor 7SCR and tos.
Since it is sent only to the gate of cR, photocoupler 4PC
and 7PC are turned on, and among the main circuit switching thyristors shown in Fig. 1, thyristors 5CR-U and 5CR-Y are turned on.
Only conducts. Further, the thyristor 5CR=Z is made conductive by the timing pulse of the zero-phase timing signal f of the subsequent high-voltage application phase, and the thyristor 5CR-V is also made conductive at the timing of the zero-phase timing signal C of the high-voltage application phase, making it complete. It becomes three-phase operation.

That is, each line voltage between U-V, V-W, and W-U (7) is detected as a signal insulated by the photocouplers IPC, 2PC, and 3PC, and a zero-phase timing pulse is generated by the zero-phase detection memory circuit 3. .

Then, when a photographing start signal XST is sent by a photographing hand switch or the like, a zero phase timing signal of the line voltage to be turned on, which is stored in advance by the zero phase detection storage circuit 3, is sent to the photographing timer circuit 5. A signal indicating that this signal has been accepted by the photographing timer circuit 5 and the zero-phase timing signal are combined and sent to the SCR gate control circuit 6. The SCR gate control circuit 6 sends this signal only to the corresponding main circuit switching thyristors. Therefore, each line of the three phases is not completely conductive, and only one of the main circuit switching thyristors connected in antiparallel is conductive, and the direction of the current is restricted. However, this is of course only at the initial stage of introduction,
After shifting to three-phase operation, as is clear from the three-phase line voltage diagram, there is a period in which the anti-parallel main circuit switching thyristors conduct simultaneously, and each line appears to be completely conductive. It has become.

Furthermore, in response to the end signal from the photographing timer circuit 5, the zero phase detection and storage circuit 3 stores the next input phase and performs reverse phase input.

〔effect〕

As explained above, according to the novel technical means disclosed in this application, the following effects can be obtained.

(1) Detects the zero phase of each three-phase line voltage, and uses this detection signal to sequentially apply voltage while limiting the direction of the voltage flowing to each three-phase line. Since the chute is held down, it can be made less susceptible to the impedance of the power supply and high voltage system.

(2) According to (1) above, adjustment can also be made unnecessary.

(3) According to (1) above, the circuit structure can be made less susceptible to the influence of the impedance of each line even when combined with an anti-phase input method that can be assembled at low cost.

The present invention has been specifically explained above using examples, but
It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.

For example, in the above embodiment, the method for preventing biased magnetization is as follows:
Although we adopted the reverse phase input method, it can of course be combined with the DC magnetization method. However, when the input phase is different each time, such as in reverse-phase input, the method of the above-described embodiment exhibits a remarkable effect.

[Brief explanation of the drawing]

1 to 3 are diagrams for explaining a three-phase X-ray high voltage control device according to an embodiment of the present invention, and FIG. 1 shows the main circuit of the three-phase X-ray high voltage control device. 2 is a circuit diagram showing the configuration of the three-phase high voltage power-on control device of the main circuit shown in FIG. 1, and FIG. 3 is a circuit diagram showing the configuration of the three-phase high voltage power-on control device of the main circuit shown in FIG. FIG. 2 is a time chart for explaining the operation of FIG. In the figure, 1-... three-phase power supply, 5CR-U, SC: R-V. 5CR-W, 5CR-X, 5CR-Y, 5CR-Z...
・Main circuit switching thyristor, 2...High voltage generator,
3... Zero phase detection storage circuit, 4. Ant game 1-circuit, 5... Shooting timer circuit, 6... SCR game 1-control circuit.

Claims (1)

[Claims] (1) In a three-phase high voltage control device using the primary side control method,
Line-to-line voltage detection means for detecting the zero phase of each line-to-line voltage of the three phases, and a high voltage detection means for sequentially applying voltage to each line of the three phases while limiting the direction of the voltage flowing to each line based on the output of the line-to-line voltage detection means. A three-phase high voltage control device characterized by being equipped with voltage input means.