Compact solid state klystron power supply

• US 5,930,125 A
• Filed: 08/28/1996
• Issued: 07/27/1999
• Est. Priority Date: 08/28/1996
• Status: Expired due to Term

• Current Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Original Assignee: Siemens Medical Systems, Inc. (Siemens AG)
• Inventors: Thompson, Lance W., Marziale, Michael J., Hitchcock, Roger N.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): JARDIEU, DEREK
• Application Number:
  US08/704,054
• Time in Patent Office: 1,063 Days
• Field of Search: 363/26, 363/89, 363/133, 363/134, 363/21, 219/715, 219/716, 219/761, 307/110
• US Class Current: 363/26
• CPC Class Codes: A61N 5/10 X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy A61N5/01 takes precedence
• CPC Class Codes: H03K 17/105 in thyristor switches
• CPC Class Codes: H03K 17/567 Circuits characterised by the use of more than one type of semiconductor device, e.g. BIMOS, composite devices such as IGBT
• CPC Class Codes: H03K 17/601 using transformer coupling H03K17/61 takes precedence
• CPC Class Codes: H03K 3/57 the switching device being a semiconductor device

Abstract

A high voltage pulse generating circuit for powering klystrons, and the like. The circuit includes a source of D.C. power having positive and negative terminals, a flyback transformer having a primary winding and a secondary winding, the primary winding having first and second terminals for connection to the source of D.C. power, a sensor for generating a signal indicating the amplitude of the current in the primary winding, and a solid state switching circuit for coupling the source of D.C. power to the primary winding of the flyback transformer. The primary winding is coupled to the power source in response to a control signal, and decoupled from the power source when a predetermined level of current is detected in the primary winding.

Claims

1. A high voltage pulse generating circuit, comprising:

a source of D.C. power having positive and negative terminals;

a flyback transformer having a primary winding and a secondary winding, the primary winding having first and second terminals for connection to the source of D.C. power;

sensing circuitry for generating a signal indicative of current flowing in the primary winding, the signal indicating the amplitude of the current; and

a solid state switching circuit for coupling the positive and negative terminals of the source of D.C. power to the first and second terminals of the primary winding of the flyback transformer in response to a control signal and for decoupling the D.C. power source from the primary winding in response to the signal indicating that a predetermined level of current is flowing in the primary winding, the solid state switching circuit comprising at least one conduction path for directing energy stored in a leakage inductance associated with the flyback transformer into the D.C. power source.

2. The high voltage pulse generating circuit of claim 1, further comprising:

a pulse forming network coupled to the first and second terminals of the secondary winding; and

a high voltage switch for shorting the pulse forming network in response to a shorting signal.

3. The high voltage pulse generating circuit of claim 2, wherein the high voltage switch includes a plurality of SCR stages, each SCR stage comprising an SCR, a resistor, and a control signal generator, the SCR having an anode, a cathode, and a gate, the SCR conducting current from the anode to the cathode in the presence of a control signal generating a potential between the gate and the cathode, the control signal being generated by the control signal generator, the resistor being connected between the anode and cathode, the stages being connected such that the SCRs are connected in series.

4. The high voltage pulse generating circuit of claim 3, wherein the control signal generator in each the stage comprises a secondary winding of a pulse transformer, each said secondary winding being coupled to a common primary winding.

5. The high voltage pulse generating circuit of claim 1, wherein the solid state switching circuit comprises first and second IGBTs, the first IGBT coupling the first terminal of the primary winding to the positive terminal of the source of D.C. power when the first IGBT is in a conducting state, and the second IGBT coupling the second terminal of the primary winding to the negative terminal of the source of D.C. power when the second IGBT is in a conducting state.

6. The high voltage pulse generating circuit of claim 1, wherein said at least one conduction path comprises first and second diodes coupling said first and second terminals of said primary winding to said positive and negative terminals of said source of D.C. power.

7. The high voltage pulse generating circuit of claim 1, wherein the source of D.C. power is greater than 250 volts and less than 10 kV.

8. The high voltage pulse generating circuit of claim 1, wherein the sensing circuitry for generating a signal indicative of current flowing in the primary winding is a sensor.

9. The high voltage pulse generating circuit of claim 1, further comprising a pulse forming network coupled to the first and second terminals of the secondary winding, said pulse forming network including inductors with slugs, the slugs capable of varying an inductance of said pulse forming network.

10. A high voltage pulse generating circuit in a radiation treatment device, comprising:

a radiation source capable of generating a radiation beam having a variable radiation output;

a source of D.C. power having positive and negative terminals;

a flyback transformer having a primary winding and a secondary winding, said primary winding having first and second terminals configured to be alternately connected to and disconnected from said positive and negative terminals of said source of D.C. power; and

sensing circuitry for generating a signal indicative of current flowing in said primary winding, said signal indicating the amplitude of said current;

wherein said source of D.C. power, said flyback transformer and said sensing circuitry are used to supply power to said radiation source such that said radiation beam is generated.

11. The high voltage pulse generating circuit in a radiation treatment device of claim 10, further comprising a solid state switching circuit for coupling said source of D.C. power to said primary winding of said flyback transformer in response to a control signal and for decoupling said D.C. power source from said primary winding in response to said signal indicating that a predetermined level of current was flowing in said primary winding.

12. The high voltage pulse generating circuit in a radiation treatment device of claim 11, wherein said solid state switching circuit comprises first and second IGBTs, said first IGBT coupling said first terminal of said primary winding to said positive terminal of said source of D.C. power when said first IGBT is in a conducting state, and said second IGBT coupling said second terminal of said primary winding to said negative terminal of said source of D.C. power when said second IGBT is in a conducting state.

13. The high voltage pulse generating circuit in a radiation treatment device of claim 11, wherein said solid state switching circuit further comprises first and second diodes coupling said first and second terminals of said primary winding to said positive and negative terminals of said source of D.C. power.

14. The high voltage pulse generating circuit in a radiation treatment device of claim 10, further comprising:

a pulse forming network coupled to said first and second terminals of said secondary winding; and

a high voltage switch for shorting said pulse forming network in response to a shorting signal.

15. The high voltage pulse generating circuit in a radiation treatment device of claim 14, said high voltage switch including a plurality of SCR stages, each said SCR stage comprising an SCR, a resistor, and a control signal generator, said SCR having an anode, a cathode, and a gate, said SCR conducting current from said anode to said cathode in the presence of a control signal generating a potential between said gate and said cathode, said control signal being generated by said control signal generator, said resistor being connected between said anode and cathode, said stages being connected such that said SCR'"'"'s are connected in series.

16. The high voltage pulse generating circuit in a radiation treatment device of claim 15, wherein said control signal generator in each said stage comprises a secondary winding of a pulse transformer, each said secondary winding being coupled to a common primary winding.

17. The high voltage pulse generating circuit in a radiation treatment device of claim 10, wherein said first and second terminals of said secondary winding are a pulse forming network, said pulse forming network including inductors with slugs, said slugs capable of varying an inductance of said pulse forming network.