Electric power conversion systems – Current conversion – Using semiconductor-type converter
Reexamination Certificate
1999-04-27
2001-12-04
Wong, Peter S. (Department: 2838)
Electric power conversion systems
Current conversion
Using semiconductor-type converter
C363S065000
Reexamination Certificate
active
06327163
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to solid state pulsed power supplies and more particularly to a high repetition rate, fast rise time solid state power supply capable of operating at voltages and currents in the kilovolt and kiloamp ranges respectively, and of driving nonlinear loads, including gas discharges, vacuum devices, and electromagnetic loads, as well as more conventional inductive, capacitive or resistive loads.
BACKGROUND OF THE INVENTION
There are many application in science, industry, military, and other fields, including driving large lasers, pulsed radar systems and various sources of electromagnetic radiation, where requirements exists for a power supply capable of producing pulses in the kilovolt and kiloamp range at high pulse repetition rates, for example 10 to 100 pulses per second (pps) with fast rise times in the microsecond range. While spark gap driven drivers have in the past been used in some such applications, such drivers are not capable of sustained operation at repetition rates of hundreds of pulses per second and, being spark gap devices, have relatively short lifetimes, requiring frequent servicing. Such devices are therefore not suitable for many applications in for example industry where millions of pulses may be generated in a single day and months, or even years, of service free operation are desired.
One way to achieve more reliable operation is to utilize an all solid state driver. However, it has not heretofore been possible to directly obtain the high rates of current rise required for such a power supply directly from solid state switches, and it has therefore been necessary to employ such solid state switching to discharge an energy storage capacitor through solid state switches at a slower rate consistent with the capacity of such switches and to then compress the pulse using for example non-linear magnetic or non-linear capacitive compression to obtain the desired fast rise times. However, such compression techniques are costly and bulky because the discharge energy must be stored within each stage of the pulse compression apparatus. A need therefore exists for an improved solid state pulsed power supply which is capable of providing kilovolt and kiloamp pulses at high repetition rates with fast pulse rise times on the order of kiloamps/microsecond, and, which power supply is capable of generating large numbers of pulses, in excess of 10
7
and preferably substantially higher, without requiring servicing.
SUMMARY OF THE INVENTION
In accordance with the above, this invention provides a solid state power supply which includes a capacitor component connected to be charged from a high voltage source, a thyristor switch through which the capacitor component discharges, a trigger circuit for the thyristor switch and a nonlinear impedance element in series with the thyristor switch, the nonlinear impedance element initially providing a high impedance to current flow in a given direction, which impedance decreases as current flow continues. The nonlinear impedance element protects thyristors of the thyristor switch by delaying current flow through the thyristors of the switch until there has been substantial spacial current spread in the thyristors. The current capacity of the power supply may be enhanced by providing a plurality of power supply modules in parallel, each of which modules has a capacitor component charging though a thyristor switch connected in series with a nonlinear impedance element, the triggering circuit being operative to trigger the thyristor switches for all of the modules substantially simultaneously.
For preferred embodiments, the thyristor switch includes a plurality of thyristors connected in series, the number of thyristors being sufficient to support a selected voltage output from the power supply. Circuitry is also provided for maintaining a substantially equal voltage across each of the thyristors. For these embodiments, the trigger circuit simultaneously applies trigger pulses to each of the thyristors. The switch preferably includes resistive and capacitive grading elements across each thyristor to assure equal voltages thereacross, and preferably also includes circuitry which protects the thyristors from being overloaded. The overload protection circuit may for example include a surge suppressor across each thryistor. The overload protect circuit may also include a monitor for each thyristor, triggering being aborted if an abnormal voltage is detected across a thyristor by a corresponding monitor.
Each thyristor is preferably of a type with wide area gate electrodes facilitating fast current rise times which are preferably in the submicrosecond range. The nonlinear impedance element is preferably a saturable magnetic output stage which preferably includes at least one serially connected ferrite core and a reset circuit to ensure that each core is in its high impedance unsaturated state before the resistor switch is triggered. The saturable magnetic output stage may also include a cylindrical conductor passing through a center of each ferrite core and a coaxial return conductor surrounding the cores, with both the cylindrical conductor and the return conductor being in close proximity to the cores so as to maximize saturated inductance of the output stage. The reset circuit for the output stage preferable includes a series connected low pass filter.
The power supply also preferably includes an energy snubber in parallel with the capacitor component which snubber may include at least one series connected, fast recover diode in series with at least one series connected low inductance resistor. An energy recovery circuit may be substituted for the resistor, which circuit stores energy applied thereto and transfers the stored energy to the capacitor component before triggering of the thyristor switch. The power supply may also include a mechanism which cools at least selected components of the power supply, low inductance current returns surrounding the components of the power supply to reduce the overall inductance thereof and/or a pulse sharpening stage which is preferably in the form of a capacitor component across the output of the thyristor switch.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawings.
REFERENCES:
patent: 4698518 (1987-10-01), Pacaia
patent: 5331234 (1994-07-01), Merritt et al.
patent: 5448580 (1995-09-01), Birx et al.
patent: 5682303 (1997-10-01), Goad
patent: 5914974 (1999-06-01), Partlo et al.
patent: 5936988 (1999-08-01), Partlo et al.
Laxton Gary L.
Science Research Laboratory, Inc.
Wong Peter S.
LandOfFree
Solid state pulsed power supply does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Solid state pulsed power supply, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Solid state pulsed power supply will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2581360