US-20260129738-A1 - ELECTRONIC CIRCUIT AND METHOD FOR PROVIDING A HIGH TUBE VOLTAGE FOR AN X-RAY TUBE, METHOD FOR OPERATING AN X-RAY TUBE, X-RAY TUBE SYSTEM AND MEDICAL IMAGING APPARATUS

US20260129738A1US 20260129738 A1US20260129738 A1US 20260129738A1US-20260129738-A1

Abstract

A first inverter unit receives an input DC voltage and converts the input DC voltage into a first AC voltage based on a first manipulated variable. A second inverter unit converts the input DC voltage into a second AC voltage based on a second manipulated variable. A further circuit part generates the high tube voltage based on the first and second AC voltages. A controller determines a controlled variable, and changes the first and/or the second manipulated variable based on the controlled variable. The controlled variable is based on a first alternating current resulting from the first AC voltage and a second alternating current resulting from the second AC voltage, and/or a first direct current resulting from the input DC voltage at the first inverter unit and a second direct current resulting from the input DC voltage at the second inverter unit.

Inventors

Leopold Ott
Stefan Waffler

Assignees

Siemens Healthineers Ag

Dates

Publication Date: 20260507
Application Date: 20251105
Priority Date: 20241106

Claims (20)

1 . An electronic circuit to provide a high tube voltage for an X-ray tube, the electronic circuit comprising: a first inverter unit configured to receive an input DC voltage and convert the input DC voltage into a first AC voltage based on a first manipulated variable; a second inverter unit configured to receive the input DC voltage and convert the input DC voltage into a second AC voltage based on a second manipulated variable; a further circuit part configured to generate the high tube voltage based on the first AC voltage and the second AC voltage, and make the high tube voltage available on an output side; and a controller configured to determine a controlled variable, and change at least one of the first manipulated variable or the second manipulated variable based on the controlled variable, to control the controlled variable to a setpoint value, wherein the controller is configured to determine the controlled variable based on at least one of a first alternating current resulting from the first AC voltage and a second alternating current resulting from the second AC voltage, or a first direct current resulting from the input DC voltage at the first inverter unit and a second direct current resulting from the input DC voltage at the second inverter unit.
2 . The electronic circuit as claimed in claim 1 , wherein the controlled variable depends on at least one of a difference between the first alternating current and the second alternating current or a difference between the first direct current and the second direct current.
3 . The electronic circuit as claimed in claim 1 , wherein the controller is configured to determine a first characteristic value from the first alternating current and a second characteristic value from the second alternating current; the controlled variable depends on the first characteristic value and the second characteristic value or the controlled variable depends on a difference between the first characteristic value and the second characteristic value; the first characteristic value corresponds to a first effective value, a first rectified value or a first peak value; and the second characteristic value corresponds to a second effective value, a second rectified value or a second peak value.
4 . The electronic circuit as claimed in claim 3 , wherein the controller is configured to ascertain a largest characteristic value based on the first characteristic value and the second characteristic value, change the first manipulated variable based on the controlled variable when the first characteristic value is less than the largest characteristic value, and change the second manipulated variable based on the controlled variable when the second characteristic value is less than the largest characteristic value.
5 . The electronic circuit as claimed in claim 1 , wherein at least one of the controller is configured to ascertain a controller manipulated variable based on the controlled variable and the setpoint value, and the first manipulated variable depends on a difference between an initial value and the controller manipulated variable, or the second manipulated variable depends on a sum of the initial value and the controller manipulated variable.
6 . The electronic circuit as claimed in claim 1 , wherein the further circuit part includes a voltage transformer configured to receive, on a primary side, a primary alternating voltage resulting from at least one of the first AC voltage or the second AC voltage, and convert the primary alternating voltage into a secondary alternating voltage, wherein the high tube voltage is based on the secondary alternating voltage.
7 . The electronic circuit as claimed in claim 6 , wherein the further circuit part includes a rectifier configured to convert the secondary alternating voltage into the high tube voltage.
8 . The electronic circuit as claimed in claim 1 , wherein the further circuit part includes a first resonant circuit, the first resonant circuit being coupled to an output of the first inverter unit on an input side, and the first resonant circuit being coupled, on an output side, to an output of the further circuit part which is configured to provide the high tube voltage; and the further circuit part includes a second resonant circuit, the second resonant circuit being coupled to an output of the second inverter unit on an input side, and the second resonant circuit being coupled, on an output side, to the output of the further circuit part.
9 . The electronic circuit as claimed in claim 8 , wherein an output of the first resonant circuit and an output of the second resonant circuit are coupled to one another.
10 . The electronic circuit as claimed in claim 1 , further comprising: at least one further inverter unit, wherein each further inverter unit, of the at least one further inverter unit, is configured to receive the input DC voltage, and convert the input DC voltage into a respective further AC voltage based on a respective further manipulated variable; the further circuit part is configured to generate the high tube voltage based on the respective further AC voltages; and the controller is configured to determine the controlled variable based on at least one of the first alternating current, the second alternating current and a respective further alternating current resulting from the respective further AC voltages, or the first direct current, the second direct current and a respective further direct current resulting from the input DC voltage at each further inverter unit.
11 . An X-ray tube system comprising: the electronic circuit as claimed in claim 1 ; and an X-ray tube.
12 . A medical imaging system including the X-ray tube system as claimed in claim 11 .
13 . A method for providing a high tube voltage for an X-ray tube, the method comprising: converting an input DC voltage into a first AC voltage based on a first manipulated variable; converting the input DC voltage into a second AC voltage based on a second manipulated variable; generating the high tube voltage based on the first AC voltage and the second AC voltage; determining a controlled variable based on at least one of a first alternating current resulting from the first AC voltage and a second alternating current resulting from the second AC voltage, or a first direct current resulting from the input DC voltage at a first inverter unit and a second direct current resulting from the input DC voltage at a second inverter unit; and changing at least one of the first manipulated variable or the second manipulated variable based on the controlled variable, to control the controlled variable to a setpoint value.
14 . The method as claimed in claim 13 , wherein the controlled variable depends on at least one of a difference between the first alternating current and the second alternating current or a difference between the first direct current and the second direct current, or the controlled variable depends on a difference between a first characteristic value of the first alternating current and a second characteristic value of the second alternating current, wherein the first characteristic value corresponds to a first effective value, a first rectified value or a first peak value, and the second characteristic value corresponds to a second effective value, a second rectified value or a second peak value.
15 . A method for operating an X-ray tube, the method comprising: performing the method of claim 13 ; and generating X-rays by the X-ray tube based on the high tube voltage.
16 . The electronic circuit as claimed in claim 2 , wherein at least one of the controller is configured to ascertain a controller manipulated variable based on the controlled variable and the setpoint value, and the first manipulated variable depends on a difference between an initial value and the controller manipulated variable, or the second manipulated variable depends on a sum of the initial value and the controller manipulated variable.
17 . The electronic circuit as claimed in claim 3 , wherein at least one of the controller is configured to ascertain a controller manipulated variable based on the controlled variable and the setpoint value, and the first manipulated variable depends on a difference between an initial value and the controller manipulated variable, or the second manipulated variable depends on a sum of the initial value and the controller manipulated variable.
18 . The electronic circuit as claimed in claim 3 , wherein the further circuit part includes a voltage transformer configured to receive, on a primary side, a primary alternating voltage resulting from at least one of the first AC voltage or the second AC voltage, and convert the primary alternating voltage into a secondary alternating voltage, wherein the high tube voltage is based on the secondary alternating voltage.
19 . The electronic circuit as claimed in claim 3 , wherein the further circuit part includes a first resonant circuit, the first resonant circuit being coupled to an output of the first inverter unit on an input side, and the first resonant circuit being coupled, on an output side, to an output of the further circuit part which is configured to provide the high tube voltage; and the further circuit part includes a second resonant circuit, the second resonant circuit being coupled to an output of the second inverter unit on an input side, and the second resonant circuit being coupled, on an output side, to the output of the further circuit part.
20 . The electronic circuit as claimed in claim 3 , further comprising: at least one further inverter unit, wherein each further inverter unit, of the at least one further inverter unit, is configured to receive the input DC voltage, and convert the input DC voltage into a respective further AC voltage based on a respective further manipulated variable; the further circuit part is configured to generate the high tube voltage based on the respective further AC voltages; and the controller is configured to determine the controlled variable based on at least one of the first alternating current, the second alternating current and a respective further alternating current resulting from the respective further AC voltages, or the first direct current, the second direct current and a respective further direct current resulting from the input DC voltage at each further inverter unit.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S) The present application claims priority under 35 U.S.C. § 119 to European Patent Application No. 24211204.3, filed Nov. 6, 2024, the entire contents of which is incorporated herein by reference. FIELD One or more example embodiments of the present invention relate to an electronic circuit for providing a high tube voltage for an X-ray tube. One or more example embodiments of the present invention also relate to an X-ray tube system with such an electronic circuit and a medical imaging system with such an X-ray tube system. One or more example embodiments of the present invention further relate to corresponding methods. BACKGROUND An X-ray tube is a special type of electron beam tube for generating X-rays. X-ray tubes are used in various imaging methods and offer a wide range of possibilities, including in modern medicine. The generation of X-rays by an X-ray tube requires free electrons that can be accelerated from a cathode to an anode with the aid of a defined high tube voltage. The electrons released, i.e., charges, per unit of time that flow from the cathode to the anode are referred to as tube current. The high tube voltage can typically range from 25 kV to 600 kV. When the accelerated electrons strike the anode, they release energy, which results in energy and characteristic radiation. Since the incident electrons can be deflected or scattered in all directions, they release different amounts of energy in the form of bremsstrahlung depending on the angle of deflection. This creates a continuous X-ray spectrum. An overall efficiency of an X-ray tube system, i.e., the radiation yield in relation to the input energy, can be very low. For this reason, it may be necessary to supply the X-ray tube with very high power, for example in the order of magnitude of 100 kW. X-ray tubes are conventionally supplied with power by a power electronic conversion chain. This, for example, first converts a single-phase or three-phase supply AC voltage into an input DC voltage, which is also referred to as the DC link voltage. In a further step, this DC link voltage is used to generate a high-frequency (for example 30 kHz-300 kHz) AC voltage with adjustable amplitude via a transmission circuit to the X-ray tube. Herein, the transmission circuit can contain a resonant circuit, a high-voltage transformer and high-voltage rectification. The level of the high-frequency AC voltage can, for example, be adjusted by actively regulating the DC link voltage, by phase-shifting at least one bridge arm of an inverter or by varying the frequency of the AC voltage. The purpose of this transmission circuit is to generate a high-voltage DC voltage between the anode and cathode inside the tube, which accelerates the free electrons from a correspondingly heated emitter, which can also be referred to as a filament, on one side of the cathode, thereby forming the current inside the X-ray tube. This current flow in turn generates high-energy X-rays when it strikes the anode, which can be used for medical imaging. As X-ray tubes, in particular, for CT and radiography applications, can have maximum beam powers in the range of 100 kW and above, power transmission can, for example, be divided into several stages due to the thermal stress on the components of the inverter stage. This can disadvantageously lead to an asymmetrical current and thus power distribution due to an inevitable tolerance in different stages, for example a tolerance of components in the transmission circuit. SUMMARY It is an object of one or more example embodiments of the present invention to reduce the asymmetry of load distribution in multistage supply circuits for the high tube voltage of an X-ray tube. At least this object is achieved by the respective subject matter of the independent claims. Advantageous developments and preferred embodiments are the subject matter of the dependent claims, the following description and the figures. One or more example embodiments of the present invention are based on the idea of ensuring more symmetrical load distribution of the multistage supply circuit via output-side control within the framework of AC voltage generation. According to one aspect of one or more example embodiments of the present invention, an electronic circuit for providing a high tube voltage for an X-ray tube is presented. The electronic circuit has a first inverter unit which is configured to receive an input DC voltage and convert the input DC voltage depending upon a first manipulated variable into a first AC voltage. Furthermore, the electronic circuit has a second inverter unit which is configured to receive the input DC voltage and to convert the input DC voltage into a second AC voltage depending upon a second manipulated variable. Moreover, the electronic circuit has a further circuit part which is configured to generate the high tube voltage depending upon the first AC voltage and the second AC voltage and to make t