# US 9,438,120 B2 · Systems and methods for fast kilovolt switching in an X-ray system

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- Number: US 9,438,120 B2
- Document ID: US9438120B2
- Status: Granted
- Kind: B2
- Application number: 14/160,919
- Filed: 2014-01-22
- Published: 2015-07-23
- Granted: 2016-09-06
- Earliest claimed: 2014-01-22
- Assignees: General Electric Company
- Applicants: General Electric Company
- Inventors: Antonio Caiafa; Philippe Ernest; Dominique Poincloux
- Web page: https://patentgrep.com/patent/US9438120B2

## CPC

- H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)}
- H02M 7/10: arranged for operation in series, e.g. for multiplication of voltage
- H02M 7/4807: {having a high frequency intermediate AC stage}
- H05G 1/58: Switching arrangements for changing-over from one mode of operation to another, e.g. from radioscopy to radiography, from radioscopy to irradiation {or from one tube voltage to another}
- H02M 7/4815: {Resonant converters (H02M7/4811 and H02M7/4826 take precedence)}
- Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- H05G: X-RAY TECHNIQUE (investigating or analysing materials by the use of X-rays G01N23/00; apparatus for X-ray photography G03B42/02; X-ray tubes H01J35/00; TV systems having X-ray input H04N5/321)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

A system includes a two-channel inverter for receiving a non-zero variable input voltage, first and second input channels each electrically coupled to the two-channel inverter, a transformer having a primary winding in electrical communication with the first and second input channels and secondary windings, and an active resonant circuit in electrical communication with the secondary windings for generating a switching output voltage at each of two different voltage levels. The active resonant circuit includes switching devices arranged in an anti-parallel configuration, a capacitor electrically coupled in series with the switching devices for receiving and storing energy during a first portion of a resonance cycle and for discharging the energy during a second portion of the resonance cycle, an inductor electrically coupled in series with the capacitor and the switching devices for transferring the energy to and from the capacitor during the resonance cycle, and an output.

## Claims

### Claim 1

A voltage switching system comprising:
a two-channel inverter configured to receive a non-zero variable input voltage from a voltage source;
a first input channel and a second input channel each electrically coupled to the two-channel inverter;
a transformer having a primary winding in electrical communication with the first input channel and the second input channel, and a plurality of secondary windings; and
an active resonant circuit in electrical communication with the secondary windings of the transformer and configured to generate a switching output voltage at each of two different voltage levels, each of the two different voltage levels being different than the non-zero variable input voltage, the active resonant circuit comprising:
a plurality of switching devices arranged in an anti-parallel configuration;
a capacitor electrically coupled in series with the plurality of switching devices and configured to receive and store energy during a first portion of a resonance cycle and further configured to discharge the energy during a second portion of the resonance cycle;
an inductor electrically coupled in series with the capacitor and the plurality of switching devices and configured to transfer the energy to and from the capacitor during the resonance cycle; and
an output configured to be electrically coupled to a load.

### Claim 2 (depends on 1)

The voltage switching system of claim 1, wherein the plurality of switching devices are configured to recirculate the energy stored in the capacitor via the inductor during a subsequent resonance cycle.

### Claim 3 (depends on 2)

The voltage switching system of claim 2, wherein the active resonant circuit is further configured to generate one of the two different voltage levels during the first portion of the resonance cycle and another one of the two different voltage levels during the second portion of the resonance cycle.

### Claim 4 (depends on 1)

The voltage switching system of claim 1, further comprising a resonant tank electrically interposed between the primary winding of the transformer and one of the first input channel and the second input channel.

### Claim 5 (depends on 1)

The voltage switching system of claim 1, further comprising a slip-ring electrically interposed between the transformer and the two-channel inverter.

### Claim 6 (depends on 1)

The voltage switching system of claim 1, further comprising a rectifier electrically interposed between the secondary windings of the transformer and the active resonant circuit.

### Claim 7 (depends on 1)

The voltage switching system of claim 1, wherein:
the transformer is a first transformer;
the active resonant circuit is a first active resonant circuit; and
the system further comprises:
a second transformer having a primary winding electrically interposed between the primary winding of the first transformer and one of the first input channel and the second input channel, and a plurality of secondary windings; and
a second active resonant circuit in electrical communication with the secondary windings of the second transformer and configured to generate a second switching output voltage at each of the two different voltage levels, the second active resonant circuit comprising:
a second plurality of switching devices arranged in the anti-parallel configuration;
a second capacitor electrically coupled in series with the second plurality of switching devices and configured to receive and store a second energy during the first portion of the resonance cycle and further configured to discharge the second energy during the second portion of the resonance cycle;
a second inductor electrically coupled in series with the second capacitor and the second plurality of switching devices and configured to transfer the second energy to and from the second capacitor during the resonance cycle; and
a second output electrically coupled in series with the output of the first active resonant circuit.

### Claim 8 (depends on 7)

The voltage switching system of claim 7, wherein the first transformer and the second transformer are in electrical communication with the two-channel inverter via at most two channels.

### Claim 9 (depends on 1)

The voltage switching system of claim 1, further comprising an x-ray tube connected to the output of the active resonant circuit and configured to provide two different energy spectra when powered by the two different voltage levels.

### Claim 10

A method of voltage switching comprising:
receiving a non-zero variable input voltage from a voltage source;
electrically communicating the non-zero variable input voltage to a primary winding of a transformer via a first input channel and a second input channel;
switching a plurality of switching devices arranged in an anti-parallel configuration and coupled to a plurality of secondary windings of the transformer to generate a switching output voltage at each of two different voltage levels, each of the two different voltage levels being different than the non-zero variable input voltage;
during a first portion of a resonance cycle, receiving and storing energy in a capacitor electrically coupled in series with the plurality of switching devices;
during a second portion of the resonance cycle, discharging the energy stored in the capacitor;
during the resonance cycle, transferring the energy to and from the capacitor via an inductor electrically coupled in series with the capacitor and the plurality of switching devices; and
outputting the switching output voltage to a load.

### Claim 11 (depends on 10)

The method of claim 10, further comprising recirculating the energy stored in the capacitor via the inductor during a subsequent resonance cycle using the plurality of switching devices.

### Claim 12 (depends on 11)

The method of claim 11, further comprising generating one of the two different voltage levels during the first portion of the resonance cycle and generating another one of the two different voltage levels during the second portion of the resonance cycle.

### Claim 13 (depends on 10)

The method of claim 10, further comprising electrically communicating the non-zero variable input voltage via a resonant tank interposed between the primary winding of the transformer and one of the first input channel and the second input channel.

### Claim 14 (depends on 10)

The method of claim 10, further comprising electrically communicating the non-zero variable input voltage via a slip-ring electrically interposed between the transformer and the two-channel inverter.

### Claim 15 (depends on 10)

The method of claim 10, further comprising electrically communicating a high voltage via a rectifier interposed between the secondary windings of the transformer and the active resonant circuit.

### Claim 16 (depends on 10)

The method of claim 10, wherein:
the transformer is a first transformer;
the active resonant circuit is a first active resonant circuit; and
the method further comprises:
electrically communicating the non-zero variable input voltage to a primary winding of a second transformer via the first input channel and the second input channel, the second transformer having a primary winding interposed between the primary winding of the first transformer and one of the first input channel and the second input channel;
switching a second plurality of switching devices arranged in an anti-parallel configuration and coupled to a plurality of secondary windings of the second transformer to generate a switching output voltage at each of the two different voltage levels;
during the first portion of a resonance cycle, receiving and storing a second energy in a second capacitor electrically coupled in series with the second plurality of switching devices;
during the second portion of the resonance cycle, discharging the second energy stored in the second capacitor; and
during the resonance cycle, transferring the second energy to and from the second capacitor via a second inductor electrically coupled in series with the second capacitor and the second plurality of switching devices.

### Claim 17 (depends on 16)

The method of claim 16, further comprising, during a period of non-resonance, maintaining the second energy in the second capacitor.

### Claim 18 (depends on 16)

The method of claim 16, wherein the first transformer and the second transformer are in electrical communication with the two-channel inverter via at most two channels.

### Claim 19 (depends on 10)

The method of claim 10, further comprising electrically communicating the two different voltage levels to an x-ray tube connected to the output of the active resonant circuit and configured to provide two different energy spectra when powered by the two different voltage levels.