Method modular power supply for x-ray tubes and method thereof

• US 7,830,685 B2
• Filed: 01/26/2006
• Issued: 11/09/2010
• Est. Priority Date: 01/28/2005
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Mueller, Frank, Hoffmann, Klaus, Freiheit-Jensen, Bernd, Klingelhoeller, Marc, Vollertsen, Christian, Rexhausen, Wolfgang, Wagner, Bernhard, Paul, Cornelius, Loef, Christoph
• Primary Examiner(s): Laxton; Gary L
• Assistant Examiner(s): QUDDUS, NUSRAT
• Application Number:
  US11/814,680
• Publication Number:
  US 20080130323A1
• Time in Patent Office: 1,748 Days
• Field of Search: 363 16- 19, 363/21.02, 363/21.07, 363/21.09, 363/21.1, 363/65, 363/67, 363/69, 363/70, 363/71
• US Class Current: 363/65
• CPC Class Codes: H02M 3/01 Resonant DC/DC converters
• CPC Class Codes: H02M 3/285 Single converters with a plurality of output stages connected in parallel parallel operation of a plurality of converters in dc distribution networks H02J1/10
• CPC Class Codes: H02M 3/33573 Full-bridge at primary side of an isolation transformer
• CPC Class Codes: H05G 1/12 with dc or rectified single-phase ac or double-phase

Abstract

A power supply power supply (30) comprising a DC voltage supply, a control unit and a plurality of high voltage channels (33a-33d) is suggested. Each high voltage channel (33) includes an inverter (IKTV), a resonance circuit, a transformer (TR), and a rectifier (RECT). The resonance circuit cooperates with the inverter (INV). The inverter (INV) is formed by a first switching unit and a second switching unit whereby a voltage of a first polarity can be applied to the resonance circuit in a first switching state, whereas a voltage of a second polarity can be applied to the resonance circuit in a second switching state. The switching states can be switched by the control unit in such a manner that in a first mode of an operation for high output power, the output power can be adjusted by changing the switching frequency in the range of the resonance frequency. In a second mode of operation for low output power, the output power can be adjusted by changing the duration of the switching state at an essentially constant switching frequency.

Claims

1. A power supply comprising:

a DC voltage supply;

a control unit; and

a plurality of high voltage channels, wherein each high voltage channel includes an inverter, a resonance circuit, a transformer, and a rectifier, wherein the resonance circuit cooperates with the inverter, wherein the inverter includes a first switching unit and a second switching unit configured to apply (a)(i) a voltage of a first polarity to the resonance circuit in a first switching state and (a)(ii) a voltage of a second polarity to the resonance circuit in a second switching state, wherein the control unit switches the switching states in such a manner that (b)(i) in a first mode of operation for high output power, the output power of one or more of the plurality of high voltage channels is adjusted by changing the switching frequency (f_T) in the range of the resonance frequency, and (b)(ii) in a second mode of operation for low output power, the output power of only one of the plurality of high voltage channels is adjusted by changing the duration of the switching state at an essentially constant switching frequency while all other high voltage channels remain inactive, wherein the essentially constant switching frequency is at least a predetermined factor lower than the resonance frequency of the resonance circuit, wherein the power supply further includes a total output power range divided into a number of ranges, wherein each range is defined by a number of active high voltage channels of the plurality of high voltage channels, wherein the control unit is further configured to increase/decrease the output power of the power supply within the total output power range by (c)(i) activating/deactivating sequentially additional high voltage channels of the plurality of high voltage channels, (c)(ii) modulating a switching frequency of corresponding high voltage channels to achieve smooth transitions during the switching on/off, respectively, of each additional high voltage channel, and (c)(iii) providing overlap of the output power between ranges to allow for a further smooth transition between adjacent ranges.

2. The power supply according to claim 1, wherein the plurality of high voltage channels comprises channels of different types.

3. The power supply according to claim 1, wherein the control unit switches the resonance circuits of different channels in a phase shifted manner.

4. The power supply according to claim 1, wherein the control unit is adapted to switch the resonance circuits with different frequencies (f_T) for the first mode of operation.

5. The power supply according to claim 1, wherein the control unit is arranged to switch the resonance circuits in a pulse width modulation (PWM) mode for the second mode of operation.

6. A method for operating a power supply comprising a plurality of high voltage channels, the method comprising:

modulating one out of the plurality of high voltage channels at a fixed switching frequency by pulse width modulation while all other high voltage channels remain inactive for providing a low output power mode of operation; and

modulating one or more of the plurality of high voltage channels at a changing switching frequency by pulse frequency modulation for providing a high output power mode of operation, wherein a total output power range of the power supply is divided into a number of ranges, wherein each range is defined by a number of active high voltage channels of the plurality of high voltage channels, the method further comprising;

increasing/decreasing the output power of the power supply within the total output power range by (c)(i) activating/deactivating sequentially additional high voltage channels of the plurality of high voltage channels, (c)(ii) modulating a switching frequency of corresponding high voltage channels to achieve smooth transitions during the switching on/off, respectively, of each additional high voltage channel, and (c)(iii) providing overlap of the output power between ranges to allow for a further smooth transition between adjacent ranges.

7. The method according to claim 6, further comprising permuting an active high voltage channel among the plurality of high voltage channels in the low output power mode of operation.

8. The method according to claim 7, further comprising measuring a temperature of the active high voltage channel and initiating the permutation of the high voltage channel in response to the measured temperature exceeding a predefined threshold temperature.

9. The method according to claim 7, further comprising initiating the permutation of the high voltage channels in response to a determination that the active high voltage channel has been operative for a predetermined period of time.