High voltage resonant inverter for capacitive load

• US 5,287,262 A
• Filed: 04/13/1992
• Issued: 02/15/1994
• Est. Priority Date: 04/13/1991
• Status: Expired due to Fees

• Current Assignee: Laserscope (Endo International PLC)
• Original Assignee: Heraeus Lasersonics Incorporated (Heraeus Holding GMBH)
• Inventors: Klein, Jurgen
• Primary Examiner(s): BEHA JR, WILLIAM
• Application Number:
  US07/867,737
• Time in Patent Office: 673 Days
• Field of Search: 363/134, 372/38
• US Class Current: 363/134
• CPC Class Codes: H01S 3/0975 using inductive or capacitive excitation
• CPC Class Codes: H02M 7/48 using discharge tubes with control electrode or semiconductor devices with control electrode

Abstract

An inductor is connected in parallel with an electrical load which, together with the capacitive components of the load, forms a resonant circuit. An auxiliary inductance coupled to the aforesaid conductor is energized periodically. During the oscillations, the resonant circuit delivers the energy to the load. The power dissipation of the switches is very low, due to the auxiliary inductance and the resonant circuit. The high-voltage generator is particularly suitable for gas lasers.

Claims

1. A high voltage generator for an electrical load having capacitive components, comprising:

a main inductor connector across and in parallel with the electrical load, said main inductor and the load constituting a resonant circuit;

an auxiliary inductor magnetically coupled to the main inductor;

a drive circuit including the auxiliary inductor and a pair of parallel connected switches connected across an alternating current source having a peak current to energize periodically the electrical load; and

means for opening and closing the pair of parallel switches alternately in push pull relationship at times to apply to the auxiliary inductor a current below the peak current of the current source.

2. The generator of claim 1, wherein the means for opening and closing the pair of switches includes means for switching at times to apply to the auxiliary inductor during switching a current smaller than the peak current by at least one-half.

3. The generator of claim 1, wherein the means for opening and closing the pair of switches include means for switching at times to provide a current flowing through each of the pair of switches of approximately zero value at switch-off time.

4. The generator of claim 1, wherein the switches comprise semiconductor elements.

5. The generator of claim 1, further comprising an automatic matching device for matching the resonant frequency to the load to optimize the switching times of the pair of switches.