High-voltage, high-current, solid-state closing switch
View Patent ↗A high-voltage, high-current, solid-state closing switch uses a field-effect transistor (e.g., a MOSFET) to trigger a high-voltage stack of thyristors. The switch can have a high hold-off voltage, high current carrying capacity, and high time-rate-of-change of current, di/dt. The fast closing switch can be used in pulsed power applications.
1. A high-voltage, high-current solid-state closing switch, comprising:
a thyristor stack comprising two or more thyristors arranged in a series and/or parallel arrangement, the thyristor stack having an anode terminal and a cathode terminal;
a blocking diode having an anode terminal and a cathode terminal, wherein the anode terminal of the blocking diode is electrically connected to the cathode terminal of the thyristor stack;
a trigger capacitor having a first terminal and a second terminal, wherein the first terminal is electrically connected to the cathode terminal of the thyristor stack and the anode terminal of the blocking diode which enables charging of the trigger capacitor through the blocking diode;
a field-effect transistor having a drain electrically connected to the second terminal of the trigger capacitor and a source electrically connected to the cathode terminal of the blocking diode;
a means for charging the trigger capacitor to below the maximum reverse hold-off voltage of the blocking diode; and
a means for applying a voltage between the anode terminal of the thyristor stack and the cathode terminal of the blocking diode, such that the voltage applied to the thyristor stack is less than the self-break voltage of the thyristor stack;
wherein the thyristor stack is switched on when a trigger is applied to the gate terminal of the field-effect transistor, thereby closing the field-effect transistor and shorting the second terminal of the trigger capacitor to low voltage, thereby causing a transient reduction of the voltage at the cathode terminal of the thyristor stack and the anode terminal of the blocking diode, thereby causing the voltage applied to the thyristor stack to exceed the self-break voltage.
2. The switch of claim 1 , wherein the thyristor stack comprises a two-terminal thyristor and wherein the thyristor stack is switched on by causing the voltage applied to the thyristor stack to exceed the self-break voltage.
3. The switch of claim 1 , wherein the thyristor stack comprises a three-terminal thyristor having a gate terminal and wherein the thyristor stack is switched on by causing the voltage applied to the thyristor stack to exceed the self-break voltage while simultaneously drawing current into the gate terminal of the three-terminal thyristor.
4. The switch of claim 3 , further comprising a current limiting resistor between the gate terminal of the three-terminal thyristor and the cathode terminal of the blocking diode.
5. The switch of claim 1 , wherein the field-effect transistor comprises a metal-oxide-semiconductor field-effect transistor.
6. The switch of claim 1 , wherein the self-break voltage of the thyristor stack is greater than 1000 V.
7. The switch of claim 1 , wherein the switch has a current carrying capacity of greater than 1 kA.
8. The switch of claim 1 , wherein the switch has a time rate-of-change of current greater than 10 kA/μs.
9. The method of triggering either the switch of claim 1 or the switch of claim 3 that results in transition of the switch to the on state while carrying very little current thus enhancing the di/dt capability of the switch without device failure due to filamentation.