High-voltage x-ray generator

• US 6,738,275 B1
• Filed: 11/13/2000
• Issued: 05/18/2004
• Est. Priority Date: 11/10/1999
• Status: Expired due to Term

• Current Assignee: Electromed International Limited
• Original Assignee: Electromed International Limited
• Inventors: Beland, Robert
• Primary Examiner(s): HAN, YOUNGHUIE JESSICA
• Application Number:
  US09/711,789
• Time in Patent Office: 1,282 Days
• Field of Search: 363/65, 363/66, 363/67, 363/69, 363/70, 363/71, 363/21.02, 363/21.03
• US Class Current: 363/71
• CPC Class Codes: H02M 1/0077 Plural converter units whose outputs are connected in series
• CPC Class Codes: H02M 1/088 for the simultaneous control of series or parallel connected semiconductor devices
• CPC Class Codes: H02M 3/3376 with automatic control of output voltage or current
• CPC Class Codes: H02M 7/003 Constructional details, e.g. physical layout, assembly, wiring or busbar connections
• CPC Class Codes: H02M 7/49 Combination of the output voltage waveforms of a plurality of converters
• 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 1/12 with dc or rectified single-phase ac or double-phase
• CPC Class Codes: 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
• CPC Class Codes: Y10T 29/49071 by winding or coiling

Abstract

A power supply for a device which has a load, comprising a first resonant generator and a second resonant generator, coupled in parallel, each generator having a phase output. The power supply further comprises a control circuit coupled to the first and second generators controlling the first and second phase outputs, wherein the first phase output and the second phase output are summed to provide a variable power supply to the load.

Claims

1. A high-voltage power supply for a device which has a load, comprising:

a first resonant inverter providing a first output signal and a second resonant inverter providing a second output signal;

a control circuit including a voltage controlled oscillator and a phase shifter, said control circuit being coupled to the first inverter and to the second inverter constructed to control a phase difference between said first output signal and said second output signal; and

at least one high-voltage transformer including a primary side and a secondary side providing power to a load;

said primary side including a first pair of primary coils connected in parallel to receive the first output signal and including a second pair of primary coils connected in parallel to receive the second output signal;

the high-voltage transformer being constructed so that the first output signal having a first phase and the second output signal having a second phase are summed to provide a variable power to the load depending on the phase difference between the first phase and the second phase.

2. The power supply as claimed in claim 1, wherein the load is a medical device.

3. The power supply as claimed in claim 1 wherein the control circuit is constructed for pulse width modulation of the first and second resonant inverters.

4. The power supply as claimed in claim 1, wherein the load is a medical device designed to receive a DC voltage.

5. The power supply as claimed in claim 1, wherein the first output signal is coupled to said first pair of primary coils using a first switch and the second output signal is coupled to said second pair of primary coils using a second switch and wherein said first and second switches are selectively openable while providing power to the load.

6. The power supply as claimed in claim 1, wherein the first inverter and the second inverter receive clock inputs at the same frequency but having different phases.

7. The power supply as claimed in claim 1, wherein the control circuit comprises a control signal generator providing input to at least one of said inverters.

8. The power supply as claimed in claim 7, wherein the control signal generator includes said voltage controlled oscillator, said phase shifter, an amplifier and an isolation transformer.

9. The power supply as claimed in claim 7, wherein the control circuit is constructed to generate a first clock output coupled to the first inverter, and generate a second clock output coupled to the second inverter.

10. The power supply as claimed in claim 1, wherein the first inverter and the second inverter receive one clock input having the same frequency and the same phase.

11. The power supply as claimed in claim 1, wherein the secondary side includes plurality of secondary coils each said secondary coil corresponding to one primary coil.

12. The power supply as claimed in claim 11 further comprising a plurality of capacitors associated with said plurality of secondary coils, each said capacitor being connected across an output of one said secondary coil to form an LC circuit element.

13. The power supply as claimed in claim 11 further comprising a high voltage rectifier stack having a plurality of multiplication modules, each multiplication module having an AC input connected to said secondary coil and a DC output.

14. The power supply as claimed in claim 13, wherein the AC inputs of the multiplication modules are connected in parallel.

15. The power supply as claimed in claim 14, wherein the parallel connections of the multiplication modules are through at least one coupling voltage limiting device.

16. The power supply as claimed in claim 15, wherein the plurality of multiplication modules further comprises a DC return resistor mechanism across at least one of the coupling voltage limiting devices.

17. The power supply as claimed in claim 13, wherein the DC outputs of the multiplication modules are connected in series.

18. The power supply as claimed in claim 13, wherein the plurality of multiplication modules comprise an output filter voltage limiting device across each DC output of the multiplication modules.

19. The power supply as claimed in claim 18, wherein a capacitance of the coupling voltage limiting devices is at least less than a capacitance of the output filter voltage limiting devices connected across the DC outputs of the multiplication modules connected in parallel.

20. The power supply as claimed in claim 13, wherein the plurality of multiplication modules comprises a full-wave bridge.

21. The power supply as claimed in claim 20, wherein the full-wave bridge includes a four diode bridge.

22. The power supply as claimed in claim 13 further comprising a capacitor connected across each said AC input and each said secondary coil.

23. The power supply as claimed in claim 1 further comprising a load sharing mechanism constructed to substantially equalize power load on each said resonant inverter.

24. The power supply as claimed in claim 23 wherein said load sharing mechanism includes a first tertiary primary coil associated with said first pair of primary coils and a second tertiary primary coil associated with said second pair of primary coils, said tertiary primary coils being connected in parallel.

25. The power supply as claimed in claim 23 including a first switch constructed and arranged to couple the first output signal to said first pair of primary coils, and a second switch constructed and arranged to couple the second output signal to said second pair of primary coils, said first and second switches being selectively openable while providing power to the load.

26. The power supply as claimed in claim 1 further comprising:

a third resonant inverter providing a third output signal, and a fourth resonant inverter providing a fourth output signal; and

at least another one high-voltage transformer including a primary side and a secondary side providing power to a load;

said primary side including a third pair of primary coils connected in parallel to receive the third output signal and including a fourth pair of primary coils connected in parallel to receive the fourth output signal, wherein said control circuit is constructed to control a phase difference between said third output signal and said fourth output signal.

27. The power supply as claimed in claim 26 wherein the control circuit is constructed for pulse width modulation of the first, second, third and fourth resonant inverters.

28. The power supply as claimed in claim 26 further comprising a load sharing mechanism constructed to substantially equalize power load on each said resonant inverter.

29. The power supply as claimed in claim 28 wherein said load sharing mechanism includes a first tertiary primary coil associated with said first pair of primary coils, a second tertiary primary coil associated with said second pair of primary coils, said first and second tertiary primary coils being connected in parallel, and further includes a third tertiary primary coil associated with said third pair of primary coils and a fourth tertiary primary coil associated with said fourth pair of primary coils, said third and fourth tertiary primary coils being connected in parallel.

30. The power supply as claimed in claim 28 including

a first switch constructed and arranged to couple the first output signal to said first pair of primary coils,

a second switch constructed and arranged to couple the second output signal to said second pair of primary coils,

a third switch constructed and arranged to couple the third output signal to said third pair of primary coils, and

a fourth switch constructed and arranged to couple the fourth output signal to said fourth pair of primary coils, said first, second, third and fourth switches being selectively openable while providing power to the load.

31. The power supply as claimed in claim 26 wherein each said resonant inverter includes at least two power transistors, each said transistor having its gate controlled by a signal from said control circuit.

32. The power supply as claimed in claim 1 wherein each said resonant inverter includes at least two power transistors, each said transistor having its gate controlled by a signal from said control circuit.

33. A method for controlling a first resonant inverter and a second resonant inverter connected in parallel, each resonant inverter having a phase output, the method comprising the steps of:

setting a first phase to the output of the first resonant inverter;

setting a second phase to the output of the second resonant inverter;

selectively shifting at least one phase output of the resonant inverter for achieving a predetermined magnitude of a voltage in a predetermined time; and

sharing load between said first and second resonant inverters using inductive coupling to substantially equalize power load on each said resonant inverter.

34. The method as claimed in claim 33 further comprising the step of summing the first and second phase outputs.

35. The method as claimed in claim 33, wherein the first and second generators are resonant generators controlled to provide a variable frequency output.

36. A high-voltage power supply, comprising:

a first resonant inverter providing a first output signal and a second resonant inverter providing a second output signal;

a control circuit including a voltage controlled oscillator and a phase shifter, said control circuit being coupled to the first inverter and to the second inverter and constructed to control a phase difference between said first output signal and said second output signal; and

an inductive a load sharing mechanism constructed to substantially equalize power load on each said resonant inverter when said the first output signal having a first phase and the second output signal having a second phase are combined to provide a power to the load.

37. The power supply as claimed in claim 36, wherein the control circuit is constructed for pulse width modulation of the first and second resonant inverters.

38. The power supply as claimed in claim 36, wherein the control circuit is constructed vary a frequency of the first and second output signal provided by the respective first and second resonant inverters and thereby vary power provided to the load.

39. The power supply as claimed in claim 36, wherein the control circuit including the phase shifter are constructed vary said phase difference of the first and second output signal and thereby vary power provided to the load.

40. The power supply as claimed in claim 36, wherein each said resonant inverter includes at least two power transistors, each said transistor having its gate controlled by a signal from said control circuit.