OPTIMIZED SWITCHING FOR A MULTILEVEL GENERATOR

• US 20130070901A1
• Filed: 09/18/2012
• Published: 03/21/2013
• Est. Priority Date: 09/19/2011
• Status: Abandoned Application

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Grassl, Tobias
• Application Number:
  US13/622,221
• Publication Number:
  US 20130070901A1
• Time in Patent Office: Days
• US Class Current: 378/111
• CPC Class Codes: H02M 1/0095 Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck
• CPC Class Codes: H02M 7/483 Converters with outputs that each can have more than two voltages levels
• CPC Class Codes: H02M 7/4835 comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
• CPC Class Codes: H05G 1/10 Power supply arrangements for feeding the X-ray tube supply circuits with converters in general H02M; supply circuits for emitters and amplifiers H04B1/16 - H04B1/1623
• CPC Class Codes: H05G 1/32 Supply voltage of the X-ray apparatus or tube

Abstract

A method for the generation of drive signals for a multilevel generator comprising a number of cells that may be switched independently of each other is provided. Each of the cells is provided to output a cell voltage based on a respective drive signal. The drive signals of the cells overall output a multilevel quantized reference signal. The method includes splitting the multilevel quantized reference signal such that at least two drive signals of different cells contribute to a quantization level of the quantized reference signal in a predetermined period.

Claims

1. A method for the generation of drive signals for a multilevel generator comprising a plurality of cells that are switchable independently of each other, each cell of the plurality of cells operable to output a cell voltage based on a respective drive signal, wherein the drive signals of the plurality of cells overall are operable to output a multilevel quantized reference signal, the method comprising:

splitting the multilevel quantized reference signal such that at least two of the drive signals contribute to a quantization level of the quantized reference signal in a predetermined period, the at least two drive signals being of different cells of the plurality of cells.

2. The method as claimed in claim 1, wherein the quantized reference signal comprises a plurality of partial signals, the number of the plurality of partial signals being smaller than or equal to the number of the plurality of cells.

3. The method as claimed in claim 2, wherein the quantized reference signal and the plurality of partial signals are periodic,

wherein the method further comprises allocating the periodic partial signals to the drive signals in each period of the quantized reference signal, and

wherein the predetermined period is a multiple of the period of the quantized reference signal.

4. The method as claimed in claim 2, further comprising splitting the quantized reference signal in the drive signals such that drive times of individual cells of the plurality of cells in the predetermined period are the same.

5. The method as claimed in claim 4, further comprising determining a positive edge or a negative edge of the quantized reference signal or the plurality of partial signals in the predetermined period;

and

activating or deactivating the drive signal belonging to a cell of the plurality of cells with the shortest or longest drive time.

6. The method as claimed in claim 5, further comprising activating or deactivating the drive signal belonging to a cell of the plurality of cells with the fewest switching operations.

7. The method as claimed in claim 6, further comprising determining the cell with the shortest or longest drive time before the cell with the fewest switching operations.

8. The method as claimed in claim 6, further comprising resetting a number of the switching operations, the drive times, or the switching operations and the drive times of each cell of the plurality of cells following the expiration of the predetermined period.

9. The method as claimed in claim 7, wherein the drive time of two cells of the plurality of cells is the same when the respective drive times lie within a predetermined tolerance band.

10. The method as claimed in claim 7, wherein cells of the plurality of cells with the fewest switching operations are determined before the cell with the shortest or longest drive time.

11. The method as claimed in claim 7, further comprising weighting the drive times or the number of the switching operations of the individual cells with a weighting factor.

12. The method as claimed in claim 11, wherein the weighting factor is dependent on an output current of the multilevel generator, an output voltage of the multilevel generator at a time of a determination of the drive time, or a combination thereof.

13. The method as claimed in claim 4, further comprising activating or deactivating the drive signal belonging to a cell of the plurality of cells with the fewest switching operations.

14. The method as claimed in claim 7, further comprising resetting a number of the switching operations, the drive times, or the switching operations and the drive times of each cell of the plurality of cells following the expiration of the predetermined period.

15. The method as claimed in claim 8, wherein the drive time of two cells of the plurality of cells is the same when the respective drive times lie within a predetermined tolerance band.

16. The method as claimed in claim 9, wherein cells of the plurality of cells with the fewest switching operations are determined before the cell with the shortest or longest drive time.

17. The method as claimed in claim 9, further comprising weighting the drive times or the number of the switching operations of the individual cells with a weighting factor.

18. A device configured for generating drive signals for a multilevel generator comprising a plurality of cells that are switchable independently of each other, each cell of the plurality of cells operable to output a cell voltage based on a respective drive signal, wherein the drive signals of the plurality of cells overall are operable to output a multilevel quantized reference signal, the device being further configured to:

split the multilevel quantized reference signal such that at least two of the drive signals contribute to a quantization level of the quantized reference signal in a predetermined period, the at least two drive signals being of different cells of the plurality of cells.

19. A circuit comprising:

a multilevel generator with cells that are switchable independently of each other, each of the cells operable to output a cell voltage based on a respective drive signal; and

a device configured to;

generate the drive signals for the multilevel generator, wherein the drive signals of the cells overall are operable to output a multilevel quantized reference signal; and

split the multilevel quantized reference signal such that at least two of the drive signals contribute to a quantization level of the quantized reference signal in a predetermined period, the at least two drive signals being of different cells of the plurality of cells.

20. An X-ray device comprising:

an X-ray source; and

a circuit operable to supply the X-ray source with electrical energy, the circuit comprising;

a multilevel generator with cells that are switchable independently of each other, each of the cells operable to output a cell voltage based on a respective drive signal; and

a device configured to;

generate the drive signals for the multilevel generator, wherein the drive signals of the cells overall are operable to output a multilevel quantized reference signal; and

split the multilevel quantized reference signal such that at least two of the drive signals contribute to a quantization level of the quantized reference signal in a predetermined period, the at least two drive signals being of different cells of the plurality of cells.