CN109787494B

CN109787494B - Voltage switching circuit and dual-energy CT

Info

Publication number: CN109787494B
Application number: CN201910193303.2A
Authority: CN
Inventors: 吴景林; 祝国平; 陈青昌; 褚旭
Original assignee: Shanghai United Imaging Healthcare Co Ltd
Current assignee: Shanghai United Imaging Healthcare Co Ltd
Priority date: 2019-03-14
Filing date: 2019-03-14
Publication date: 2020-12-22
Anticipated expiration: 2039-03-14
Also published as: CN109787494A

Abstract

The embodiment of the invention discloses a voltage switching circuit and a dual-energy CT. The voltage switching circuit includes: the first switching output end, the second switching output end and the rectifying and filtering module are connected between the first switching output end and the second switching output end; the rectification filter module comprises a filter unit connected to the output end of the rectification filter module, the voltage of the output end of the rectification filter module is a first voltage, the capacitance value of the filter unit is set as a first capacitance value, the voltage of the output end of the rectification filter module is a second voltage, and the capacitance value of the filter unit is set as a second capacitance value; the first voltage is greater than the second voltage, and the first capacitance is less than the second capacitance. Compared with the prior art, the embodiment of the invention realizes the effects of improving the voltage switching speed, reducing the cost and having a large applicable load current range.

Description

Voltage switching circuit and dual-energy CT

Technical Field

The embodiment of the invention relates to the technical field of electronic circuits, in particular to a voltage switching circuit and a dual-energy CT.

Background

An electronic Computed Tomography (CT) apparatus is widely used in the detection fields of medical examination, industrial detection, security detection, and the like. With the development of the technological level and the computer technology, the CT is also rapidly developed, and the dual-energy CT is developed in order to obtain a more accurate detection result.

The operating principle of the dual-energy CT is that the inverter, the high-voltage transformer, and the rectifying and filtering module form a high-voltage generator, the voltage output by the high-voltage generator is rapidly changed between two voltage levels (for example, the low voltage level is 80kV, and the high voltage level is 140kV), the bulb tube is used as an X-ray generating source to emit two X-rays with different energy levels and energies respectively under the two voltage levels, and accordingly, the X-ray detector (X-ray detector) can obtain dual-energy data. And, the shorter the switching time between the two voltage levels, the more separation of dual-energy data is facilitated; conversely, the longer the switching time between the two voltage levels, the greater the dose of ineffective X-rays emitted, and the fewer the number of effective views per CT revolution. Therefore, a shorter voltage switching time is a trend of the high voltage generator of the dual energy CT. The switching of the voltage grade comprises a high-voltage working mode and a low-voltage working mode, and in the process of switching from the low-voltage working mode to the high-voltage working mode, the current stress of the inverter can be far greater than the current stress of the inverter when the high-voltage generator outputs in a stable state, so that the requirement on the short-time high-power output capacity of the inverter is high; in the process of switching from the high-voltage working mode to the low-voltage working mode, the energy in the filter capacitor is mainly extracted by the tube current of the bulb tube, so that the switching time is relatively short when large current is output, and the switching time is relatively long when small current is output.

In the prior art, an inverter with a short-time high current and good stress is added with an output filter capacitor with a small capacitance value, and the scheme can shorten the switching time, however, the cost of the inverter is increased, and the improvement effect on the falling time of a high-voltage generator under a low current is not good. Therefore, the prior art has the problems of low voltage switching speed and high cost.

Disclosure of Invention

The embodiment of the invention provides a voltage switching circuit and a dual-energy CT (current transformer) to achieve the purposes of improving the voltage switching speed and reducing the cost.

In a first aspect, an embodiment of the present invention provides a voltage switching circuit, where the voltage switching circuit includes: the first switching output end and the second switching output end, and a rectification filter module connected between the first switching output end and the second switching output end;

the rectification filter module comprises a filter unit connected to the output end of the rectification filter module, the voltage of the output end of the rectification filter module is a first voltage, the capacitance value of the filter unit is set as a first capacitance value, the voltage of the output end of the rectification filter module is a second voltage, and the capacitance value of the filter unit is set as a second capacitance value; the first voltage is greater than the second voltage, and the first capacitance value is less than the second capacitance value.

Optionally, the output end of the rectifying and filtering module includes a first output end and a second output end;

the filtering unit comprises a first filtering unit and a second filtering unit, wherein a first end of the first filtering unit is electrically connected with a first output end of the rectification filtering module, and a second end of the second filtering unit is electrically connected with a second output end of the rectification filtering module;

the rectification filtering module comprises:

a first input end of the first rectifying unit is used as a first input end of the rectifying and filtering module, a second input end of the first rectifying unit is used as a second input end of the rectifying and filtering module, a first output end of the first rectifying unit is electrically connected with a first output end of the rectifying and filtering module, and a second output end of the first rectifying unit is electrically connected with a second output end of the rectifying and filtering module;

the first filtering switching unit comprises a first end, a second end, a third end and a fourth end; a first end of the first filtering switching unit is electrically connected with a first output end of the rectifying and filtering module, a second end of the first filtering switching unit is electrically connected with a second end of the first filtering unit, a third end of the first filtering switching unit is electrically connected with a first end of the second filtering unit, and a fourth end of the first filtering switching unit is electrically connected with a second output end of the rectifying and filtering module; the first filtering switching unit is used for setting the first filtering unit and the second filtering unit to be connected in series when the output end voltage of the rectifying and filtering module is a first voltage, and setting the first filtering unit and the second filtering unit to be connected in parallel when the output end voltage of the rectifying and filtering module is a second voltage.

Optionally, the first filtering switching unit includes:

a first transistor, a first end of which is electrically connected with a first end of the first filtering switching unit, and a second end of which is electrically connected with a third end of the first filtering switching unit;

a first end of the second transistor is electrically connected with a third end of the first filtering switching unit, and a second end of the second transistor is electrically connected with a second end of the first filtering switching unit;

a third transistor, a first end of the third transistor is electrically connected to the first end of the first filtering switching unit, and a second end of the third transistor is electrically connected to the fourth end of the first filtering switching unit;

wherein a cathode of a body diode of a transistor serves as a first terminal of the transistor; an anode of a body diode of the transistor serves as a second terminal of the transistor.

Optionally, the first transistor, the second transistor, and the third transistor are MOSFETs or IGBTs.

Optionally, the first filtering switching unit includes:

a cathode of the first diode is electrically connected with a first end of the first filter switching unit, and an anode of the first diode is electrically connected with a third end of the first filter switching unit;

a first end of the fourth transistor is electrically connected with the third end of the first filtering switching unit, and a second end of the fourth transistor is electrically connected with the second end of the first filtering switching unit;

a fifth transistor, a first end of which is electrically connected to the first end of the first filtering switching unit, and a second end of which is electrically connected to the fourth end of the first filtering switching unit;

Optionally, the first rectifying unit is: a full bridge rectifier circuit, a voltage doubler rectifier circuit, or a CW circuit.

Optionally, the rectifying and filtering module is a first rectifying and filtering module;

the voltage switching circuit further includes:

a first inverter;

a first transformer, a primary side winding of which is electrically connected with an output end of the first inverter; the input end of the first rectifying and filtering module is electrically connected with a secondary side winding of the first transformer; the first output end of the first rectifying and filtering module is electrically connected with the first switching output end;

a second inverter;

the primary side winding of the second transformer is electrically connected with the output end of the second transformer;

the input end of the second rectifying and filtering module is electrically connected with a secondary side winding of the second transformer; the first output end of the second rectifying and filtering module is electrically connected with the second output end of the first rectifying and filtering module; and the second output end of the second rectifying and filtering module is electrically connected with the second switching output end.

Optionally, the output voltage of the first switching output end and the second switching output end is a first voltage kV _ h or a second voltage kV _ l;

the output voltage of the first rectifying and filtering module is kV _ h-kV _ l or 2(kV _ h-kV _ l);

the output voltage of the second rectifying and filtering module is 2kV _ l-kV _ h.

the filtering unit comprises a third filtering unit and a fourth filtering unit, wherein the first end of the third filtering unit is electrically connected with the first output end of the rectification filtering module, and the second end of the fourth filtering unit is electrically connected with the second output end of the rectification filtering module;

the rectification filtering module comprises:

a first input end of the second rectifying unit is used as a first input end of the rectifying and filtering module, a second input end of the second rectifying unit is used as a second input end of the rectifying and filtering module, a first output end of the second rectifying unit is electrically connected with a first output end of the rectifying and filtering module, and a second output end of the second rectifying unit is electrically connected with a second output end of the rectifying and filtering module; the second rectifying unit is used for setting the second rectifying unit to be in a first topological structure when the voltage at the output end of the rectifying and filtering module is a first voltage, and setting the second rectifying unit to be in a second topological structure when the voltage at the output end of the rectifying and filtering module is a second voltage;

the second filtering switching unit comprises a first end, a second end, a third end, a fourth end and a fifth end; a first end of the second filtering switching unit is electrically connected with a first output end of the rectifying and filtering module, a second end of the second filtering switching unit is electrically connected with a second end of the third filtering unit, a third end of the second filtering switching unit is electrically connected with a second input end of the rectifying and filtering module, a fourth end of the second filtering switching unit is electrically connected with a first end of the fourth filtering unit, and a fifth end of the second filtering switching unit is electrically connected with a second output end of the rectifying and filtering module; the second filtering switching unit is used for setting the capacitance value of the filtering unit as the capacitance value of the third filtering unit or the capacitance value of the fourth filtering unit when the output end voltage of the rectifying and filtering module is a first voltage, and setting the third filtering unit and the fourth filtering unit to be connected in parallel when the output end voltage of the rectifying and filtering module is a second voltage.

Optionally, the second rectifying unit includes:

the anode of the second diode is electrically connected with the first input end of the second rectifying unit, and the cathode of the second diode is electrically connected with the first output end of the second rectifying unit;

the anode of the third diode is electrically connected with the second output end of the second rectifying unit, and the cathode of the third diode is electrically connected with the first input end of the second rectifying unit;

a cathode of the fourth diode is electrically connected with the first output end of the second rectifying unit;

a sixth transistor, a first end of which is electrically connected to the second input end of the second rectifying unit, and a second end of which is electrically connected to an anode of the fourth diode;

a seventh transistor, a second end of the seventh transistor being electrically connected to the second input end of the second rectifying unit;

an anode of the fifth diode is electrically connected with the second output end of the second rectifying unit, and a cathode of the fifth diode is electrically connected with the first end of the seventh transistor;

Optionally, the second filtering switching unit includes:

a first end of the eighth transistor is electrically connected with the third end of the second filtering switching unit, and a second end of the eighth transistor is electrically connected with the second end of the second filtering switching unit;

a ninth transistor, a first end of which is electrically connected to the fourth end of the second filtering switching unit, and a second end of which is electrically connected to the third end of the second filtering switching unit;

a tenth transistor, a first end of the tenth transistor is electrically connected to the first end of the second filtering switching unit, and a second end of the tenth transistor is electrically connected to the fourth end of the second filtering switching unit;

a first end of the eleventh transistor is electrically connected with the second end of the second filtering switching unit, and a second end of the eleventh transistor is electrically connected with the fifth end of the second filtering switching unit;

Optionally, the rectifying and filtering module is a third rectifying and filtering module;

the voltage switching circuit further includes:

a third inverter;

a third transformer, a primary winding of which is electrically connected to an output terminal of the third inverter; the third transformer comprises a first secondary side winding and a second secondary side winding; a first input end of the third rectifying and filtering module is electrically connected with a first end of the first secondary side winding; a second input end of the third rectifying and filtering module is electrically connected with a second end of the first secondary side winding; the first output end of the third rectifying and filtering module is electrically connected with the first switching output end;

a first input end of the fourth rectifying and filtering module is electrically connected with a first end of the second secondary side winding; a second input end of the fourth rectifying and filtering module is electrically connected with a second end of the second secondary side winding; the first output end of the fourth rectifying and filtering module is electrically connected with the second output end of the third rectifying and filtering module; and a second output end of the fourth rectifying and filtering module is electrically connected with the second switching output end.

the output voltage of the third rectifying and filtering module is kV _ h-kV _ l or 2(kV _ h-kV _ l);

the output voltage of the fourth rectifying and filtering module is 2kV _ l-kV _ h.

Optionally, the method further comprises: the number of the rectification filter modules is N;

a first output end of the first rectifying and filtering module is electrically connected with the first switching output end, a fourth end of the ith rectifying and filtering module is electrically connected with a first output end of the (i + 1) th rectifying and filtering module, and a fourth end of the nth rectifying and filtering module is electrically connected with the second switching output end; n is more than or equal to 1, and i is more than or equal to 1 and less than N.

Optionally, the voltage switching circuit further comprises: and the control system is connected with the voltage switching circuit and is used for controlling the voltage of the voltage output end of the voltage switching circuit.

In a second aspect, an embodiment of the present invention further provides a dual-energy CT, where the dual-energy CT includes: a voltage switching circuit and a bulb according to any embodiment of the invention;

the power supply end of the bulb tube is electrically connected with the voltage output end of the voltage switching circuit, and the high-voltage generator is used for supplying power to the bulb tube.

In the embodiment of the invention, the capacitance value of the filtering unit of the rectifying and filtering module is switched to be set as the first capacitance value, and the voltage of the output end of the rectifying and filtering module is the first voltage; the capacitance value of the filtering unit is set as a second capacitance value, and the voltage of the output end of the rectifying and filtering module is a second voltage; and the voltage and the capacitance value of the filtering unit are in negative correlation, so that the charge quantity of the filtering unit is almost unchanged in the switching process of outputting two voltage levels, namely, the charging and discharging time of the filtering unit is reduced. Compared with the prior art, in the process of switching the output two voltage levels, the change of the charge quantity of the filtering unit is small, so that the filtering unit does not need to be charged and discharged for a long time, on one hand, the voltage switching speed is improved and is not influenced by the change of load current, and on the other hand, an inverter with good current stress does not need to be adopted. Therefore, the embodiment of the invention realizes the effects of improving the voltage switching speed, reducing the cost and having a large applicable load current range.

Drawings

Fig. 1 is a schematic circuit diagram of a voltage switching circuit according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an operation mode of the voltage switching circuit of FIG. 1;

FIG. 3 is a schematic diagram of another operation mode of the voltage switching circuit of FIG. 1;

fig. 4 is a schematic circuit diagram of another voltage switching circuit according to an embodiment of the present invention;

fig. 5 is a schematic circuit diagram of another voltage switching circuit according to an embodiment of the present invention;

FIG. 6 is a schematic diagram illustrating an operation mode of the voltage switching circuit in FIG. 5;

fig. 7 is a schematic circuit diagram of another voltage switching circuit according to an embodiment of the present invention;

fig. 8 is a schematic waveform diagram of an output voltage of a voltage switching circuit according to an embodiment of the present invention;

fig. 9 is a schematic circuit diagram of another voltage switching circuit according to an embodiment of the present invention;

FIG. 10 is a schematic diagram illustrating an operation mode of the voltage switching circuit of FIG. 9;

FIG. 11 is a schematic diagram illustrating another operation mode of the voltage switching circuit in FIG. 9;

fig. 12 is a schematic circuit diagram of another voltage switching circuit according to an embodiment of the present invention;

fig. 13 is a schematic circuit diagram of another voltage switching circuit according to an embodiment of the present invention;

fig. 14 is a schematic circuit diagram of another voltage switching circuit according to an embodiment of the present invention;

fig. 15 is a schematic circuit diagram of a dual-energy CT according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

The embodiment of the invention provides a voltage switching circuit. Fig. 1 is a schematic circuit structure diagram of a voltage switching circuit according to an embodiment of the present invention. The voltage switching circuit may be, for example, a high voltage generator, and the output voltage thereof may be 1kV to 1000 kV. Referring to fig. 1, the voltage switching circuit includes: a first switching output terminal 10 and a second switching output terminal 20, and a rectifying and filtering module 30 connected between the first switching output terminal 10 and the second switching output terminal 20; the rectifying and filtering module 30 includes a filtering unit (fig. 1 exemplarily shows that the filtering unit includes a first filtering unit 311 and a second filtering unit 312) connected to the output end thereof, the output end voltage of the rectifying and filtering module 30 is a first voltage, the capacitance value of the filtering unit is set to a first capacitance value, the output end voltage of the rectifying and filtering module 30 is a second voltage, and the capacitance value of the filtering unit is set to a second capacitance value; the first voltage is greater than the second voltage, and the first capacitance is less than the second capacitance.

The first switching output terminal 10 and the second switching output terminal 20 are output terminals of the voltage switching circuit, and a voltage difference between the first switching output terminal 10 and the second switching output terminal 20 is an output voltage of the voltage switching circuit. The input end of the rectifying and filtering module 30 may be electrically connected to, for example, a secondary winding of a high voltage transformer, the input voltage of the rectifying and filtering module 30 is provided by the high voltage transformer, the alternating current of the high voltage transformer is provided by an inverter, and the rectifying and filtering module 30 may rectify and filter the voltage input by the input end thereof.

The filter unit of the rectifying and filtering module 30 may be composed of at least two filter capacitors, for example, the first filter unit 311 is a first filter capacitor (or an equivalent first filter capacitor), the second filter unit 312 is a second filter capacitor (or an equivalent second filter capacitor), and the capacitance values of the first filter unit 311 and the second filter unit 312 are both C, and the first filter unit 311 and the second filter unit 312 are connected in series, in parallel, or only one of them is connected in a circuit.

Illustratively, the voltage switching circuit works in a high-voltage working mode (outputting a high voltage level, for example, 140kV), the capacitance of the filter unit is set to 0.5C, and the voltage at the output end of the rectifying and filtering module 30 is a first voltage V _ k _ h; in the low-voltage operation mode (outputting a low voltage level, for example, 70kV), the capacitance of the filter unit is set to 2C, the output voltage of the rectifying and filtering module 30 is the second voltage V _ k _ l, and V _ k _ l is 0.5V _ k _ h.

Therefore, in the embodiment of the present invention, the capacitance value of the filtering unit of the rectifying and filtering module 30 is switched to be set as the first capacitance value, and the voltage at the output end of the rectifying and filtering module 30 is the first voltage; the capacitance value of the filtering unit is set as a second capacitance value, and the voltage at the output end of the rectifying and filtering module 30 is a second voltage; and the voltage and the capacitance value of the filtering unit are in negative correlation, so that the charge quantity of the filtering unit is almost unchanged in the switching process of outputting two voltage levels, namely, the charging and discharging time of the filtering unit is reduced. Compared with the prior art, in the process of switching the output two voltage levels, the change of the charge quantity of the filtering unit is small, so that the filtering unit does not need to be charged and discharged for a long time, on one hand, the voltage switching speed is improved and is not influenced by the change of load current, and on the other hand, an inverter with good current stress does not need to be adopted. Therefore, the embodiment of the invention realizes the effects of improving the voltage switching speed, reducing the cost and having a large applicable load current range.

With continued reference to fig. 1, on the basis of the foregoing embodiments, optionally, the output end of the rectifying and filtering module 30 includes a first output end 301 and a second output end 302; the filtering unit includes a first filtering unit 311 and a second filtering unit 312, a first end of the first filtering unit 311 is electrically connected to the first output end 301 of the rectifying and filtering module 30, and a second end of the second filtering unit 312 is electrically connected to the second output end 302 of the rectifying and filtering module 30. The rectifying and filtering module 30 further includes: a first rectifying unit 320 and a first filtering switching unit 330, wherein a first input end 321 of the first rectifying unit 320 is used as a first input end of the rectifying and filtering module 30, a second input end 322 of the first rectifying unit 320 is used as a second input end of the rectifying and filtering module 30, a first output end 323 of the first rectifying unit 320 is electrically connected with a first output end 301 of the rectifying and filtering module 30, and a second output end 324 of the first rectifying unit 320 is electrically connected with a second output end 302 of the rectifying and filtering module 30; the first filtering switching unit 330 includes a first terminal 331, a second terminal 332, a third terminal 333, and a fourth terminal 334; a first end 331 of the first filtering switching unit 330 is electrically connected with the first output end 301 of the rectifying and filtering module 30, a second end 332 of the first filtering switching unit 330 is electrically connected with a second end of the first filtering unit 311, a third end 333 of the first filtering switching unit 330 is electrically connected with a first end of the second filtering unit 312, and a fourth end 334 of the first filtering switching unit 330 is electrically connected with the second output end 302 of the rectifying and filtering module 30; the first filtering switching unit 330 is configured to set the first filtering unit 311 and the second filtering unit 312 to be connected in series when the output end voltage of the rectifying and filtering module 30 is a first voltage, and set the first filtering unit 311 and the second filtering unit 312 to be connected in parallel when the output end voltage of the rectifying and filtering module 30 is a second voltage.

The first rectifying unit 320 may be a full-bridge rectifying circuit, a voltage doubler rectifying circuit, or a Cockcroft-Walton (Cockcroft-Walton) circuit, where the first rectifying unit 320 may convert ac input from an input terminal thereof into dc, and the Cockcroft-Walton circuit is referred to as a CW circuit for short. Illustratively, the operation process of the rectifying and filtering module 30 is, referring to fig. 2, in the high-voltage operation mode, the first terminal 331 and the third terminal 333 of the first filtering switching unit 330 are disconnected, the second terminal 332 and the fourth terminal 334 are disconnected, and the first terminal 331 and the fourth terminal 334 are connected, so that the first filtering unit 311 and the second filtering unit 312 are connected in series; after the first filtering unit 311 and the second filtering unit 312 are connected in series, the total voltage across them is V _ k _ h, and the average value of the voltage output by the secondary winding of the transformer is U _ s _ h. Referring to fig. 3, in the low-voltage operation mode, the first terminal 331 and the third terminal 333 of the first filtering switching unit 330 are turned on, the second terminal 332 and the fourth terminal 334 are turned on, and the first terminal 331 and the fourth terminal 334 are turned off, so that the first filtering unit 311 and the second filtering unit 312 are connected in parallel; after parallel connection, the voltages at two ends of the first filtering unit 311 and the second filtering unit 312 are both V _ k _ l, the average value of the voltage output by the secondary winding of the transformer is U _ s _ l, and V _ k _ h is 2V _ k _ l, and U _ s _ h is 2U _ s _ l. Assuming that the switching time of the high-voltage operating mode and the low-voltage operating mode tends to 0, the output voltage of the rectifying and filtering module 30 before and after switching satisfies V _ k _ h-2V _ k _ l, and if the loss of the capacitor energy in the switching process is considered, V _ k _ h-2V _ k _ l needs to be realized after the inverter supplements part of the energy.

Compared with the prior art, the inverter only needs to provide energy required for maintaining load current, and does not need to provide a large amount of charging energy for the filtering unit, so that short-time high-current stress of the inverter is greatly reduced. In the process of switching from a high-voltage working mode to a low-voltage working mode, the inverter needs to reduce the voltage of the secondary side winding of the transformer from U _ s _ h to U _ s _ l, and the voltage reduction process of the filtering unit does not need to be accompanied with energy release, so that the rapid voltage reduction can be realized even under a low-current load.

Fig. 4 is a schematic circuit structure diagram of another voltage switching circuit according to an embodiment of the present invention. On the basis of the above embodiments, the embodiment of the present invention provides a specific circuit structure of the first filtering switching unit 330. Referring to fig. 4, optionally, the first filtering switching unit 330 includes: a first transistor S1, a second transistor S2, and a third transistor S3. A first terminal of the first transistor S1 is electrically connected to the first terminal of the first filter switching unit 330, and a second terminal of the first transistor S1 is electrically connected to the third terminal of the first filter switching unit 330; a first terminal of the second transistor S2 is electrically connected to the third terminal of the first filtering switching unit 330, and a second terminal of the second transistor S2 is electrically connected to the second terminal of the first filtering switching unit 330; a first terminal of the third transistor S3 is electrically connected to the second terminal of the first filtering switching unit 330, and a second terminal of the third transistor S3 is electrically connected to the fourth terminal of the first filtering switching unit 330; wherein, the cathode of the body diode of the transistor is used as the first end of the transistor; the anode of the body diode of the transistor serves as the second terminal of the transistor.

The first Transistor S1, the second Transistor S2, and the third Transistor S3 are transistors having a switching function, and may be, for example, a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) or an Insulated Gate Bipolar Transistor (IGBT). For example, the first filtering switching unit 330 operates on the principle that, in the high-voltage operating mode, the first transistor S1 and the third transistor S3 are controlled to be turned off, and the second transistor S2 is controlled to be turned on, so that the first filtering unit 311 and the second filtering unit 312 are connected in series; in the low-voltage operation mode, the first transistor S1 and the third transistor S3 are controlled to be turned on, and the second transistor S2 is controlled to be turned off, so that the first filtering unit 311 and the second filtering unit 312 are connected in parallel. In the embodiment of the invention, the topology of the first filtering switching unit 330 is changed through the switching device, the circuit structure is simple, and the manufacturing cost is further reduced.

Fig. 5 is a schematic circuit structure diagram of another voltage switching circuit according to an embodiment of the present invention. On the basis of the above embodiments, the embodiment of the present invention provides another specific circuit structure of the first filtering switching unit 330. Referring to fig. 5, optionally, the first filtering switching unit 330 includes: a first diode D1, a fourth transistor S4, and a fifth transistor S5. A cathode of the first diode D1 is electrically connected to the first terminal of the first filter switching unit 330, and an anode of the first diode D1 is electrically connected to the third terminal of the first filter switching unit 330; a first terminal of the fourth transistor S4 is electrically connected to the third terminal of the first filtering switching unit 330, and a second terminal of the fourth transistor S4 is electrically connected to the second terminal of the first filtering switching unit 330; a first terminal of the fifth transistor S5 is electrically connected to the second terminal of the first filter switching unit 330, and a second terminal of the fifth transistor S5 is electrically connected to the fourth terminal of the first filter switching unit 330; wherein, the cathode of the body diode of the transistor is used as the first end of the transistor; the anode of the body diode of the transistor serves as the second terminal of the transistor.

Illustratively, the first filter switching unit 330 operates on the principle that, referring to fig. 2, in the high-voltage operating mode, the fifth transistor S5 is controlled to be turned off, the fourth transistor S4 is controlled to be turned on, and since the first diode D1 is turned off in the opposite direction, the first filter unit 311 and the second filter unit 312 are connected in series between the first output terminal 301 and the second output terminal 302 of the rectifying and filtering module 30; in the low-voltage operation mode, referring to fig. 6, the fifth transistor S5 is controlled to be turned on, the fourth transistor S4 is controlled to be turned off, and since the first diode D1 is turned off in the opposite direction, only the first filter unit 311 is connected in series between the first output terminal 301 and the second output terminal 302 of the rectifying and filtering module 30. The circuit of the embodiment of the invention has simple structure and further reduces the manufacturing cost.

It should be noted that, in the embodiment shown in fig. 4, in the high-voltage operating mode, the capacitance value of the filter unit is 0.5C, and in the low-voltage operating mode, the capacitance value of the filter unit is 2C; in the embodiment shown in fig. 5, in the high-voltage operation mode, the capacitance of the filter unit is 0.5C, and in the low-voltage operation mode, the capacitance of the filter unit is C; therefore, the capacitance value of the filtering unit of the embodiment shown in fig. 5 has a smaller variation range. Among them, the embodiment shown in fig. 4 can ensure that the first filtering unit 311 and the second filtering unit 312 are both connected in the voltage switching circuit, and therefore, the voltage (charge amount) on the first filtering unit 311 and the second filtering unit 312 is maintained. However, in the embodiment shown in fig. 5, in the low-voltage operation mode, the second filtering unit 312 is not connected to the voltage switching circuit, so that the voltage across the second filtering unit 312 decreases. During the switching from the low-voltage operating mode to the high-voltage operating mode, the embodiment shown in fig. 5 needs to recharge the second filtering unit 312, causing current fluctuations. If the voltage switching circuit provided by the embodiment of the present invention is applied to the dual-energy CT, since the single view time of the CT is very short, about several hundred μ s, even if the embodiment shown in fig. 5 is adopted, the voltage drop on the second filtering unit 312 is very small in the low-voltage operation mode, and therefore the normal operation of the dual-energy CT is not affected.

It should be noted that, in the foregoing embodiments, the voltage output by the high-voltage operating mode is twice the voltage output by the low-voltage operating mode, which is not a limitation of the present invention, and in other embodiments, the output voltages of the high-voltage operating mode and the low-voltage operating mode may be set to be any values, and may be limited in practical application as needed.

Fig. 7 is a schematic circuit structure diagram of another voltage switching circuit according to an embodiment of the present invention. Referring to fig. 7, on the basis of the above embodiments, optionally, the voltage switching circuit includes: the first rectifier filter module 31, the first inverter 41, the first transformer 51, the second inverter 42, the second transformer 52 and the second rectifier filter module 32. The primary winding of the first transformer 51 is electrically connected to the output terminal of the first inverter 41; the primary winding of the second transformer 52 is electrically connected to the output terminal of the second inverter 42. The rectifying and filtering module is a first rectifying and filtering module 31, and the input end of the first rectifying and filtering module 31 is electrically connected with the secondary side winding of the first transformer 51; the first output terminal 311 of the first rectifying and filtering module 31 is electrically connected to the first switching output terminal 10; the input end of the second rectifying and filtering module 32 is electrically connected with the secondary winding of the second transformer 52; the first output end 321 of the second rectifying and filtering module 32 is electrically connected with the second output end 312 of the first rectifying and filtering module 31; the second output end 322 of the second rectifying and filtering module 32 is electrically connected to the second switching output end 20.

The first inverter 41 provides a first ac voltage to the first transformer 51, the first transformer 51 provides a second ac voltage to the first rectifying and filtering module 31, and the first inverter 41, the first transformer 51 and the first rectifying and filtering module 31 form a first power loop. The second inverter 42 provides the third ac voltage to the second transformer 52, the second transformer 52 provides the fourth ac voltage to the second rectifying and filtering module 32, and the second inverter 42, the second transformer 52 and the second rectifying and filtering module 32 form a second power loop. The first rectifying and filtering module 31 is any one of the rectifying and filtering modules shown in fig. 1 to 6 provided in the embodiment of the present invention, and the second rectifying and filtering module 32 may be any one of the rectifying and filtering modules provided in the embodiment of the present invention, and may also be any one of the modules having a rectifying and filtering function in the prior art. The first rectifying and filtering module 31 and the second rectifying and filtering module 32 are connected in series, and the voltage between the first switching output terminal 10 and the second switching output terminal 20 is the sum of the output voltages of the first rectifying and filtering module 31 and the second rectifying and filtering module 32. In the embodiment of the present invention, two power loops are respectively provided for the first rectifying and filtering module 31 and the second rectifying and filtering module 32, so that mutual interference in different working modes is avoided. In the embodiment of the invention, two power loops are arranged to respectively provide alternating-current voltages for the first rectifying and filtering module 31 and the second rectifying and filtering module 32, and two output voltages with any voltage level can be obtained by superposing two voltage values output by the first rectifying and filtering module 31 and the second rectifying and filtering module 32.

Fig. 8 is a schematic waveform diagram of an output voltage of a voltage switching circuit according to an embodiment of the present invention. Referring to fig. 8, on the basis of the above embodiments, optionally, the output voltage of the first switching output terminal 10 and the second switching output terminal 20 is the first voltage kV _ h or the second voltage kV _ l; the output voltage of the first rectifying and filtering module 31 is kV _ h-kV _ l or 2(kV _ h-kV _ l); the output voltage of the second rectifying and filtering module 32 is 2kV _ l-kV _ h. Illustratively, the waveform 101 in fig. 8 is a waveform of the output voltage of the first rectifying and filtering module 31, and the output voltage of the first rectifying and filtering module 31 is switched between kV _ h-kV _ l and 2(kV _ h-kV _ l); the waveform 102 is a waveform of the output voltage of the second rectifying and filtering module 32, and the output voltage of the second rectifying and filtering module 32 is 2kV _ l-kV _ h; the waveform 103 is a waveform of the output voltages of the first switching output terminal 10 and the second switching output terminal 20, and the output voltages of the first switching output terminal 10 and the second switching output terminal 20 are switched between kV _ l and kV _ h. The output voltage of the second rectifying and filtering module 32 is a constant value, and when the first rectifying and filtering module 31 outputs kV _ h-kV _ l, the output voltages of the first switching output terminal 10 and the second switching output terminal 20 are the first voltage kV _ l; when the first rectifying and filtering module 31 outputs 2(kV _ h-kV _ l), the output voltages of the first switching output terminal 10 and the second switching output terminal 20 are the first voltage kV _ h. The embodiment of the invention realizes the output voltage with two voltage grades of any value.

It should be noted that, in the above embodiments, the topology of the rectifying unit is not changed during the voltage switching process, but the topology of the filtering switching unit is changed to change the capacitance value of the filtering unit, which is not a limitation of the present invention.

Fig. 9 is a schematic circuit structure diagram of another voltage switching circuit according to an embodiment of the present invention. Referring to fig. 9, on the basis of the above embodiments, optionally, the output end of the rectifying and filtering module 30 includes a first output end 301 and a second output end 302; the filtering unit comprises a third filtering unit 313 and a fourth filtering unit 314, wherein a first end of the third filtering unit 313 is electrically connected with the first output end 301 of the rectifying and filtering module 30, and a second end of the fourth filtering unit 314 is electrically connected with the second output end 302 of the rectifying and filtering module 30. The rectifying and filtering module 30 further includes: a second rectifying unit 340 and a second filtering switching unit 350; a first input end 341 of the second rectifying unit 340 serves as a first input end of the rectifying and filtering module 30, a second input end 342 of the second rectifying unit 340 serves as a second input end of the rectifying and filtering module 30, a first output end 343 of the second rectifying unit 340 is electrically connected with the first output end 301 of the rectifying and filtering module 30, and a second output end 344 of the second rectifying unit 340 is electrically connected with the second output end 302 of the rectifying and filtering module 30; the second rectifying unit 340 is configured to set the second rectifying unit 340 to be a first topology structure when the voltage at the output end of the rectifying and filtering module 30 is a first voltage, and set the second rectifying unit 340 to be a second topology structure when the voltage at the output end of the rectifying and filtering module 30 is a second voltage; the second filtering switching unit 350 includes a first terminal 351, a second terminal 352, a third terminal 353, a fourth terminal 354 and a fifth terminal 355; a first end 351 of the second filtering switching unit 350 is electrically connected with the first output end 301 of the rectifying and filtering module 30, a second end 352 of the second filtering switching unit 350 is electrically connected with a second end 352 of the third filtering unit 313, a third end 353 of the second filtering switching unit 350 is electrically connected with the second input end 342 of the rectifying and filtering module 30, a fourth end 354 of the second filtering switching unit 350 is electrically connected with the first end 351 of the fourth filtering unit 314, and a fifth end 355 of the second filtering switching unit 350 is electrically connected with the second output end 302 of the rectifying and filtering module 30; the second filtering switching unit 350 is configured to set a capacitance value of the filtering unit as a capacitance value of the third filtering unit 313 or a capacitance value of the fourth filtering unit 314 when the output end voltage of the rectifying and filtering module 30 is the first voltage, and set the third filtering unit 313 and the fourth filtering unit 314 in parallel when the output end voltage of the rectifying and filtering module 30 is the second voltage.

The topology of the second rectifying unit 340 may be a full-bridge rectifying topology, a voltage-doubler rectifying topology, or a CW rectifying topology. Illustratively, the first topology is a voltage-doubler rectification topology and the second topology is a full-bridge rectification topology. Referring to fig. 10, in a high-voltage operating mode, the topology structure of the second rectifying unit 340 is a voltage-doubling rectifying topology, the second terminal 352 and the third terminal 353 of the second filtering switching unit 350 are connected, the third terminal 353 and the fourth terminal 354 are connected, so that the first filtering unit 311 and the second filtering unit 312 are connected in series, the total voltage at the two terminals of the first filtering unit 311 and the second filtering unit 312 connected in series is V _ k _ h, and the average voltage value output by the secondary winding of the transformer is U _ s _ h; referring to fig. 11, in a low-voltage operating mode, the topological structure of the second rectifying unit 340 is a full-bridge rectifying topology, the first end 351 and the fourth end 354 of the second filtering switching unit 350 are connected, the second end 352 and the fifth end 355 are connected, so that the first filtering unit 311 and the second filtering unit 312 are connected in parallel, and after the first filtering unit 311 and the second filtering unit 312 are connected in parallel, voltages at two ends are both V _ k _ l; the average value of the voltage output by the secondary side winding of the transformer is U _ s _ l, V _ k _ h is 2V _ k _ l, and U _ s _ h is U _ s _ l.

Therefore, the voltage of the secondary side winding of the transformer is unchanged no matter in the low-voltage working mode or the high-voltage working mode. Compared with the prior art, in the process of switching from the low-voltage working mode to the high-voltage working mode, the inverter does not need to provide a large amount of charging energy for the filtering unit, so that the short-time high-current stress of the inverter is greatly reduced. In the process of switching from the high-voltage working mode to the low-voltage working mode, the voltage reduction process of the filtering unit does not need to be accompanied with energy release, so that the rapid voltage reduction can be realized even under a low-current load.

Fig. 12 is a schematic circuit structure diagram of another voltage switching circuit according to an embodiment of the present invention. Referring to fig. 11, on the basis of the above embodiments, optionally, the second rectifying unit 340 includes: a second diode D2, a third diode D3, a fourth diode D4, a sixth transistor S6, a seventh transistor S7, and a fifth diode D5. An anode of the second diode D2 is electrically connected to the first input terminal 341 of the second rectifying unit 340, and a cathode of the second diode D2 is electrically connected to the first output terminal 343 of the second rectifying unit 340; an anode of the third diode D3 is electrically connected to the second output terminal 344 of the second rectifying unit 340, and a cathode of the third diode D3 is electrically connected to the first input terminal 341 of the second rectifying unit 340; the cathode of the fourth diode D4 is electrically connected to the first output terminal 343 of the second rectifying unit 340; a first terminal of the sixth transistor S6 is electrically connected to the second input terminal 342 of the second rectifying unit 340, and a second terminal of the sixth transistor S6 is electrically connected to the anode of the fourth diode D4; a second terminal of the seventh transistor S7 is electrically connected to the second input terminal 342 of the second rectifying unit 340; an anode of the fifth diode D5 is electrically connected to the second output terminal 344 of the second rectifying unit 340, and a cathode of the fifth diode D5 is electrically connected to the first terminal of the seventh transistor S7; wherein, the cathode of the body diode of the transistor is used as the first end of the transistor; the anode of the body diode of the transistor serves as the second terminal of the transistor.

The sixth transistor S6 and the seventh transistor S7 are transistors having a switching function, and may be, for example, MOSFETs or IGBTs. Illustratively, the second rectifying unit 340 operates on the principle that, in the high-voltage operating mode, both the sixth transistor S6 and the seventh transistor S7 are controlled to be turned off, so that the second rectifying unit 340 has a first topology; in the low-voltage operation mode, the sixth transistor S6 and the seventh transistor S7 are controlled to be turned on, so that the second rectifying unit 340 has the second topology. The embodiment of the invention transforms the topological structure of the second rectifying unit 340 through the switching device, and has simple circuit structure and low cost.

With continuing reference to fig. 12, based on the above embodiments, optionally, the second filtering switching unit 350 includes: an eighth transistor S8, a ninth transistor S9, a tenth transistor S10, and an eleventh transistor S11. A first terminal of the eighth transistor S8 is electrically connected to the third terminal 353 of the second filter switching unit 350, and a second terminal of the eighth transistor S8 is electrically connected to the second terminal 352 of the second filter switching unit 350; a first terminal of the ninth transistor S9 is electrically connected to the fourth terminal 354 of the second filter switching unit 350, and a second terminal of the ninth transistor S9 is electrically connected to the third terminal 353 of the second filter switching unit 350; a first terminal of the tenth transistor S10 is electrically connected to the first terminal 351 of the second filter switching unit 350, and a second terminal of the tenth transistor S10 is electrically connected to the fourth terminal 354 of the second filter switching unit 350; a first terminal of the eleventh transistor S11 is electrically connected to the second terminal 352 of the second filter switching unit 350, and a second terminal of the eleventh transistor S11 is electrically connected to the fifth terminal 355 of the second filter switching unit 350; wherein, the cathode of the body diode of the transistor is used as the first end of the transistor; the anode of the body diode of the transistor serves as the second terminal of the transistor.

Among them, the eighth transistor S8, the ninth transistor S9, the tenth transistor S10, and the eleventh transistor S11 are transistors having a switching function, and may be, for example, a MOSFET or an IGBT. Illustratively, the second rectifying unit 340 operates on the principle that, in the high-voltage operating mode, the eighth transistor S8 and the ninth transistor S9 are controlled to be turned on, and the tenth transistor S10 and the eleventh transistor S11 are controlled to be turned off, so that the first filtering unit 311 and the second filtering unit 312 are connected in series; in the low-voltage operation mode, the eighth transistor S8 and the ninth transistor S9 are controlled to be turned off, and the tenth transistor S10 and the eleventh transistor S11 are controlled to be turned on. In the embodiment of the invention, the topological structure of the second filtering switching unit 350 is converted by the switching device, so that the circuit structure is simple, and the manufacturing cost is further reduced.

Fig. 13 is a schematic circuit structure diagram of another voltage switching circuit according to an embodiment of the present invention. Referring to fig. 13, on the basis of the foregoing embodiments, optionally, the voltage switching circuit further includes: the third inverter 43, the third transformer 53, the third rectifying and filtering module 33 and the fourth rectifying and filtering module 34, wherein the primary winding of the third transformer 53 is electrically connected with the output end of the third inverter 43; the third transformer 53 includes a first secondary side winding and a second secondary side winding. A first input end of the third rectifying and filtering module 33 is electrically connected with the first end 531 of the first secondary side winding; a second input end of the third rectifying and filtering module 33 is electrically connected with the second end 532 of the first secondary side winding; the first output end 331 of the third rectifying and filtering module 33 is electrically connected with the first switching output end 10; a first input end of the fourth rectifying and filtering module 34 is electrically connected to the first end 533 of the second secondary side winding; a second input end of the fourth rectifying and filtering module 34 is electrically connected with a second end 534 of the second secondary side winding; the first output terminal 341 of the fourth rectifying and filtering module 34 is electrically connected with the second output terminal 332 of the third rectifying and filtering module 33; the second output terminal 342 of the fourth rectifying and filtering module 34 is electrically connected to the second switching output terminal 20.

The third inverter 43 provides the fifth ac voltage to the third transformer 53, the third transformer 53 provides the sixth ac voltage to the third rectifying and smoothing module 33, the third transformer 53 provides the seventh ac voltage to the fourth rectifying and smoothing module 34, and the values of the sixth ac voltage and the seventh ac voltage are determined by the transformation ratio of the transformers. The third rectifying and filtering module 33 is any one of the rectifying and filtering modules shown in fig. 9 to 12 provided in the embodiment of the present invention, and the fourth rectifying and filtering module 34 may be any one of the rectifying and filtering modules provided in the embodiment of the present invention, or any one of the modules having a rectifying and filtering function in the prior art. The third rectifying and filtering module 33 and the fourth rectifying and filtering module 34 are connected in series, and the voltage between the first switching output terminal 10 and the second switching output terminal 20 is the sum of the output voltages of the third rectifying and filtering module 33 and the fourth rectifying and filtering module 34. In the embodiment of the present invention, the third rectifying and filtering module 33 and the fourth rectifying and filtering module 34 are respectively configured to output two voltage values, and two output voltages with arbitrary voltage levels can be obtained by superimposing the two voltage values.

On the basis of the above embodiments, optionally, the output voltage of the first switching output terminal 10 and the second switching output terminal 20 is the first voltage kV _ h or the second voltage kV _ l; the output voltage of the third rectifying and filtering module 33 is kV _ h-kV _ l or 2(kV _ h-kV _ l); the output voltage of the fourth rectifying and filtering module 34 is 2kV _ l-kV _ h. The output voltage of the fourth rectifying and filtering module 34 is a constant value, and when the third rectifying and filtering module 33 outputs kV _ h-kV _ l, the output voltages of the first switching output terminal 10 and the second switching output terminal 20 are the first voltage kV _ l; when the third rectifying and filtering module 33 outputs 2(kV _ h-kV _ l), the output voltages of the first switching output terminal 10 and the second switching output terminal 20 are the first voltage kV _ h. The embodiment of the invention realizes the output voltage with two voltage grades of any value.

It should be noted that, when the third rectifying and filtering module 33 according to the embodiment of the present invention outputs two voltage levels, the voltage output by the front-end secondary winding of the third rectifying and filtering module 33 is kept unchanged, and the voltage output by the front-end secondary winding of the fourth rectifying and filtering module 34 is kept unchanged, so that the third rectifying and filtering module 33 and the fourth rectifying and filtering module 34 may be connected to different windings of the third transformer 53. Compared with the case that the third rectifying and filtering module 33 and the fourth rectifying and filtering module 34 are respectively connected with different inverters and transformers, the embodiment of the invention further reduces the manufacturing cost of the voltage switching circuit.

Fig. 14 is a schematic circuit structure diagram of another voltage switching circuit according to an embodiment of the present invention. Referring to fig. 14, on the basis of the above embodiments, optionally, the number of the rectifying and filtering modules 30 is N; a first output end 301 of the first rectifying and filtering module 30 is electrically connected to the first switching output end 10, a fourth end of the ith rectifying and filtering module 30 is electrically connected to the first output end 301 of the (i + 1) th rectifying and filtering module 30, and a fourth end of the nth rectifying and filtering module 30 is electrically connected to the second switching output end 20; n is more than or equal to 1, and i is more than or equal to 1 and less than N.

The number of the rectifying and filtering modules 30 provided by the embodiment of the present invention is at least one, and if the number of the rectifying and filtering modules 30 is one, the output end of the rectifying and filtering module 30 is the output end of the voltage switching circuit; if the number of the rectifying and filtering modules 30 is multiple (two or more), the rectifying and filtering modules 30 are connected in series, specifically, the first output end of the first rectifying and filtering module 30 is electrically connected to the first switching output end 10, the second output end of the first rectifying and filtering module 30 is electrically connected to the first output end of the second rectifying and filtering module 30, and so on, and the second output end of the last rectifying and filtering module 30 is electrically connected to the second switching output end 20. The specific number of the rectifying and filtering modules 30 connected in series can be set as required in practical application.

On the basis of the foregoing embodiments, optionally, the voltage switching circuit further includes: and the control system is connected with the voltage switching circuit and is used for controlling the voltage of the voltage output end of the voltage switching circuit. The voltage switching circuit may include, for example, a circuit structure such as an inverter, a rectifying unit, and a smoothing switching unit. In these circuit structures, for example, various transistors may be included, and the control terminals of these transistors may be controlled by the control system to control the on and off of these transistors, so as to switch the topology of the circuit, and thus implement the switching of the voltage level.

The embodiment of the invention also provides the dual-energy CT. Fig. 15 is a schematic circuit diagram of a dual-energy CT according to an embodiment of the present invention. Referring to fig. 15, the dual energy CT includes: the voltage switching circuit 1 and the bulb 2 provided by any embodiment of the invention; the power supply end of the bulb tube 2 is electrically connected with the voltage output end of the voltage switching circuit, and the high-voltage generator is used for supplying power to the bulb tube. The voltage output end of the voltage switching circuit 1 includes a first switching output end 10 and a second switching output end 20, and a voltage difference between the first switching output end 10 and the second switching output end 20 is an output voltage of the voltage switching circuit 1.

In the embodiment of the invention, the capacitance value of the filtering unit of the rectifying and filtering module in the voltage switching circuit 1 is switched to be set as the first capacitance value, and the voltage of the output end of the rectifying and filtering module is the first voltage; the capacitance value of the filtering unit is set as a second capacitance value, and the voltage of the output end of the rectifying and filtering module is a second voltage; and the voltage and the capacitance value of the filtering unit are in negative correlation, so that the charge quantity of the filtering unit is almost unchanged in the switching process of outputting two voltage levels, namely, the charging and discharging time of the filtering unit is reduced. Compared with the prior art, in the process of switching the output two voltage levels, the change of the charge quantity of the filtering unit is small, so that the filtering unit does not need to be charged and discharged for a long time, on one hand, the voltage switching speed is improved and is not influenced by the change of load current, and on the other hand, an inverter with good current stress does not need to be adopted. Therefore, the embodiment of the invention realizes the effects of improving the voltage switching speed, reducing the cost and having a large applicable load current range.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A voltage switching circuit, comprising: the first switching output end and the second switching output end, and a rectification filter module connected between the first switching output end and the second switching output end;

the rectification filter module comprises a filter unit connected to the output end of the rectification filter module, the voltage of the output end of the rectification filter module is a first voltage, the capacitance value of the filter unit is set as a first capacitance value, the voltage of the output end of the rectification filter module is a second voltage, and the capacitance value of the filter unit is set as a second capacitance value; the first voltage is greater than the second voltage, and the first capacitance value is less than the second capacitance value;

the output end of the rectifying and filtering module comprises a first output end and a second output end;

the rectification filtering module comprises:

a first input end of the first rectifying unit is used as a first input end of the rectifying and filtering module, a second input end of the first rectifying unit is used as a second input end of the rectifying and filtering module, a first output end of the first rectifying unit is used as a first output end of the rectifying and filtering module, and a second output end of the first rectifying unit is used as a second output end of the rectifying and filtering module;

2. The voltage switching circuit according to claim 1, wherein the first filter switching unit includes:

a third transistor, a first end of the third transistor being electrically connected to the second end of the first filtering switching unit, and a second end of the third transistor being electrically connected to the fourth end of the first filtering switching unit;

3. The voltage switching circuit of claim 2, wherein the first transistor, the second transistor, and the third transistor are MOSFETs or IGBTs.

4. The voltage switching circuit according to claim 1, wherein the first filter switching unit includes:

a fifth transistor, a first end of which is electrically connected to the second end of the first filtering switching unit, and a second end of which is electrically connected to the fourth end of the first filtering switching unit;

5. The voltage switching circuit of claim 1, wherein the first rectifying unit is: a full bridge rectifier circuit, a voltage doubler rectifier circuit or a Kockcroft-Walton circuit.

6. The voltage switching circuit according to any one of claims 1 to 5, wherein the rectifying and filtering module is a first rectifying and filtering module;

the voltage switching circuit further includes:

a first inverter;

a second inverter;

a second transformer, a primary winding of which is electrically connected to an output terminal of the second inverter;

7. The voltage switching circuit of claim 6, further comprising:

the output voltage of the first switching output end and the second switching output end is a first voltage kV _ h or a second voltage kV _ l;

8. The voltage switching circuit of claim 1, further comprising: the number of the rectification filter modules is N;

9. The voltage switching circuit of claim 1, further comprising:

and the control system is connected with the voltage switching circuit and is used for controlling the voltage of the voltage output end of the voltage switching circuit.

10. A dual energy CT, comprising: the voltage switching circuit and bulb of any one of claims 1-9;

the power supply end of the bulb tube is electrically connected with the voltage output end of the voltage switching circuit, and the voltage switching circuit is used for supplying power to the bulb tube.

11. A voltage switching circuit, comprising: the first switching output end and the second switching output end, and a rectification filter module connected between the first switching output end and the second switching output end;

the rectification filtering module comprises:

12. The voltage switching circuit according to claim 11, wherein the second rectifying unit comprises:

13. The voltage switching circuit according to claim 11, wherein the second filter switching unit comprises:

14. The voltage switching circuit according to any one of claims 11-13, wherein the rectifying-filtering module is a third rectifying-filtering module;

the voltage switching circuit further includes:

a third inverter;

15. The voltage switching circuit of claim 14, further comprising:

16. The voltage switching circuit of claim 11, further comprising: the number of the rectification filter modules is N;

a first output end of the first rectifying and filtering module is electrically connected with the first switching output end, a fifth end of the ith rectifying and filtering module is electrically connected with a first output end of the (i + 1) th rectifying and filtering module, and a fifth end of the nth rectifying and filtering module is electrically connected with the second switching output end; n is more than or equal to 1, and i is more than or equal to 1 and less than N.

17. The voltage switching circuit of claim 11, further comprising:

18. A dual energy CT, comprising: the voltage switching circuit and bulb of any one of claims 11-17;