Isolating a control signal source in a high frequency power supply

• US 8,222,885 B2
• Filed: 07/22/2008
• Issued: 07/17/2012
• Est. Priority Date: 07/23/2007
• Status: Active Grant

• Current Assignee: Hüttinger Elektronik GmbH + Co. KG
• Original Assignee: Hüttinger Elektronik GmbH + Co. KG
• Inventors: Kirchmeier, Thomas, Windisch, Hans-Juergen, Glueck, Michael, Pivit, Erich
• Primary Examiner(s): STERRETT, JEFFREY L
• Application Number:
  US12/177,818
• Publication Number:
  US 20090027937A1
• Time in Patent Office: 1,456 Days
• Field of Search: 323/271, 323/282, 323/350, 323/351
• US Class Current: 323/350
• CPC Class Codes: G01R 21/06 by measuring current and voltage G01R21/08 - G01R21/133 take precedence
• CPC Class Codes: G01R 23/02 Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
• CPC Class Codes: H01J 37/32045 Circuits specially adapted for controlling the glow discharge
• CPC Class Codes: H02M 7/003 Constructional details, e.g. physical layout, assembly, wiring or busbar connections
• CPC Class Codes: H02M 7/5383 in a self-oscillating arrangement H02M7/538 takes precedence
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance
• CPC Class Codes: H05B 41/2806 with semiconductor devices and specially adapted for lamps without electrodes in the vessel, e.g. surface discharge lamps, electrodeless discharge lamps
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A high frequency power supply, in particular a plasma supply device, for generating an output power greater than 1 kW at a basic frequency of at least 3 MHz with at least one switch bridge, which has two series connected switching elements, wherein one of the switching elements is connected to a reference potential varying in operation, and is activated by a driver, and wherein the driver has a differential input with two signal inputs and is connected to the reference potential varying in operation.

Claims

1. A high frequency power supply for generating an output power greater than 1 kW at a basic frequency of at least 3 MHz, the power supply comprising:

at least one switch bridge including two series connected switching elements, and a first of the switching elements connected to a reference potential varying in operation;

a driver circuit including;

a driver configured to control the first of the switching elements, wherein the driver includes a differential input with two signal inputs and is connected to the reference potential, and wherein at least one of the two signal inputs is coupled to the reference potential via ohmic coupling; and

a signal transformer comprising a primary and a secondary winding and having a parasitic capacitance, wherein a magnitude of a resistance associated with the ohmic coupling is less than a magnitude of the parasitic capacitance; and

a control voltage source, the control voltage source connected via the signal transformer to the driver.

2. The high frequency power supply of claim 1, wherein the two signal inputs are both connected at low resistance to the reference potential.

3. The high frequency power supply of claim 1, wherein the driver circuit further includes an input network for the driver, and the input network is configured to generate a symmetrical differential input signal for the driver.

4. The high frequency power supply of claim 1, further comprising signal lines assigned to the signal inputs and terminated at low resistance between the signal transformer and the driver.

5. The high frequency power supply of claim 1, wherein outputs of the signal transformer are connected via a common mode choke to the signal inputs of the driver.

6. The high frequency power supply of claim 5, wherein a low resistance connection of the signal lines assigned to the signal inputs is provided upstream from the common mode choke.

7. The high frequency power supply of claim 1, wherein the signal transformer is configured to have a low coupling capacitance.

8. The high frequency power supply of claim 1, wherein the signal transformer has only one turn in a primary winding and one turn in a secondary winding.

9. The high frequency power supply of claim 8, wherein the signal transformer includes an element increasing the magnetic field, wherein the turn of the primary winding and the turn of the secondary winding are guided through, around or beside the element.

10. The high frequency power supply of claim 9, wherein the turn of the primary and the turn of the secondary winding are guided through, around or beside the element in such a manner that the two primary side connections of the primary and secondary windings terminate on one side of the element and the secondary side connections of the primary and secondary windings terminate on the opposite side of the element.

11. A method for operating a high frequency power supply, for generating an output power greater than 1 kW at a basic frequency of at least 3 MHz, the method comprising:

generating an output power by means of at least one switch bridge that has at least two series connected switching elements including varying a reference potential of one of the switching elements in operation;

controlling the switching element with a driver that has a differential input with two signal inputs, by applying a differential signal to the differential input; and

transmitting a control voltage from a signal transformer comprising a primary and secondary winding to the driver, the signal transformer having a parasitic capacitance;

wherein at least one of the two signal inputs is coupled to the reference potential via ohmic coupling and wherein a magnitude of a resistance associated with the ohmic coupling is less than a magnitude of the parasitic capacitance.

12. The method of claim 11, further comprising providing at least one of the signal inputs with the reference potential.

13. The method of claim 11, further comprising terminating with a low resistance the two signal inputs and/or the output of the signal transformer.

14. The method of claim 11, further comprising, at a second signal input of the driver, inducing an interfering potential by a common mode choke, wherein the interfering potential is similar to an interfering potential generated by an undesirable alternating current at a first signal input of the driver.

15. The method of claim 11, further comprising using at least one of a single turn for at least one of the primary winding and the secondary winding of the signal transformer and a configuration of the windings in the region of an element increasing the magnetic field to provide a reduced capacitive coupling of a primary winding and of a secondary winding of a signal transformer.