Marx generator with pulsating power buffer

1 . A power stage of a pulsed power generator comprising:

a half bridge based Marx generator power cell comprising:

a main capacitor connected between a positive input terminal and a negative input terminal; and

a main half bridge switch circuit connected in parallel with the main capacitor and configured to alternately connect the main capacitor in series or in parallel with a main storage capacitor of an adjoining power stage respectively corresponding to a main capacitor discharging phase and a main capacitor charging phase; and

a pulsating power buffer connected in a boost mode or a buck mode configuration and in parallel with the main capacitor, the pulsating power buffer comprising:

an auxiliary capacitor;

an inductor; and

an auxiliary half bridge switch circuit comprising first and second switches configured to be switched in a complementary manner based on a main voltage across the main capacitor to set the pulsating power buffer in a discharging phase during the main capacitor discharging phase when the main voltage is less than a threshold voltage, and set the pulsating power buffer in a charging phase during the main capacitor charging phase when the main voltage is greater than a threshold voltage,

wherein:

during the discharging phase of the pulsating power buffer a discharge current is delivered from the auxiliary capacitor through the inductor that supplements the main voltage; and

during the charging phase of the pulsating power buffer a charge current is delivered to the auxiliary capacitor through the inductor that increases a voltage across the auxiliary capacitor during the main capacitor charging phase.

2 . The power stage according to claim 1 , wherein:

the main half bridge switch circuit comprises:

a discharging switch; and

a charging switch;

the main capacitor is set in the discharging phase when the discharging switch is closed and the charging switch is open; and

the main capacitor is set in the charging phase when the discharging switch is open and the charging switch is closed.

3 . The power stage according to claim 2 , wherein:

the pulsating power buffer is connected in the buck mode configuration, in which the auxiliary half bridge switch circuit is connected in parallel with the main capacitor and the inductor is connected in series with a cathode of the auxiliary capacitor and a junction between the first and second switches;

the first and second switches are switched in a complementary manner to drive the discharge current from the auxiliary capacitor through the inductor and the first switch during the discharging phase of the pulsating power buffer; and

the first and second switches are switched in a complementary manner to drive the charge current through the first switch and the inductor to the auxiliary capacitor during the charging phase of the pulsating power buffer.

4 . The power stage according to claim 3 , wherein the first and second switches are switched at least five times during the main capacitor discharging phase based on a pulse width modulation strategy.

5 . The power stage according to claim 2 , wherein:

the pulsating power buffer is connected in the boost mode configuration, in which the inductor is connected in series between a cathode of the main capacitor and a junction between the first and second switches, the second switch is connected in parallel with the main capacitor and the first switch is connected in series between the junction and a cathode of the auxiliary capacitor;

the first and second switches are switched in a complementary manner to drive the discharge current from the auxiliary capacitor through the first switch and the inductor during the discharging phase of the pulsating power buffer; and

the first and second switches are switched in a complementary manner to drive the charge current through the inductor and the first switch to the auxiliary capacitor during the charging phase of the pulsating power buffer.

6 . The power stage according to claim 5 , wherein the first and second switches are switched at least five times during the main capacitor discharging phase based on a pulse width modulation strategy.

7 . The power stage according to claim 2 , wherein:

the main capacitor includes a cathode connected to a positive input terminal and an anode connected to a negative input terminal;

the power stage includes a diode having an anode connected to the positive input terminal and a cathode connected to a positive output terminal; and

a negative output terminal is connected to a junction between the discharging and charging switches.

8 . A pulse power generator comprising:

an input power source;

a plurality of power stages, each comprising:

a half bridge based Marx generator power cell comprising:

a main capacitor connected between a positive input terminal and a negative input terminal; and

a main half bridge switch circuit connected in parallel with the main capacitor and configured to alternately set the power cell in a discharging phase or a charging phase;

a pulsating power buffer connected in a boost mode or a buck mode configuration and in parallel with the main capacitor, the pulsating power buffer comprising:

an auxiliary capacitor;

an inductor; and

an auxiliary half bridge switch circuit including first and second switches;

a voltage detector configured to detect a main voltage across the main capacitors; and

a controller configured to:

set each power stage in a discharging phase including:

setting the main capacitor in a discharging phase including controlling the main half bridge switch to connect the main capacitor in series with the main capacitor of an adjoining power stage; and

setting the pulsating power buffer in a discharging phase including switching the first and second switches in a complementary manner when the main voltage is less than a threshold voltage to deliver a discharge current from the auxiliary capacitor through the inductor that supplements the main voltage; and

set each power stage in a charging phase including:

setting the main capacitor in a charging phase including controlling the main half bridge switch to connect the main capacitor in parallel with the input power source; and

setting the pulsating power buffer in a charging phase including switching the first and second switches in a complementary manner when the main voltage is greater than a threshold voltage to deliver a charge current to the auxiliary capacitor through the inductor that increases a voltage across the auxiliary capacitor.

9 . The pulse power generator according to claim 8 , wherein, for each power cell:

the main half bridge switch circuit comprises:

a discharging switch; and

a charging switch;

the controller sets the main capacitor in the discharging phase by closing the discharging switch and opening the charging switch; and

the controller sets the main capacitor in the charging phase by opening the discharging switch and closing the charging switch.

10 . The pulse power generator according to claim 9 , wherein, for each power stage:

the pulsating power buffer is connected in the buck mode configuration, in which the auxiliary half bridge switch circuit is connected in parallel with the main capacitor and the inductor is connected in series with a cathode of the auxiliary capacitor and a junction between the first and second switches;

the first and second switches are switched in a complementary manner to drive the discharge current from the auxiliary capacitor through the inductor and the first switch during the discharging phase of the pulsating power buffer; and

the first and second switches are switched in a complementary manner to drive the charge current through the first switch and the inductor to the auxiliary capacitor during the charging phase of the pulsating power buffer.

11 . The pulse power generator according to claim 10 , wherein, for each power stage, the controller switches the first and second switches at least five times during the main capacitor discharging phase.

12 . The pulse power generator according to claim 11 , wherein, for each power stage:

the main capacitor includes a cathode connected to a positive input terminal and an anode connected to a negative input terminal;

the power stage includes a diode having an anode connected to the positive input terminal and a cathode connected to a positive output terminal;

a negative output terminal is connected to a junction between the discharging and charging switches; and

the auxiliary capacitor is connected between the negative input terminal and a junction between the first and second switches through the inductor.

13 . The pulse power generator according to claim 9 , wherein, for each power stage:

the pulsating power buffer is connected in the boost mode configuration, in which the inductor is connected in series between a cathode of the main capacitor and a junction between the first and second switches, the second switch is connected in parallel with the main capacitor and the first switch is connected in series between the junction and a cathode of the auxiliary capacitor;

the first and second switches are switched in a complementary manner to drive the discharge current from the auxiliary capacitor through the first switch and the inductor during the discharging phase of the pulsating power buffer; and

the first and second switches are switched in a complementary manner to drive the charge current through the inductor and the first switch to the auxiliary capacitor during the charging phase of the pulsating power buffer.

14 . The pulse power generator according to claim 13 , wherein, for each power stage, the controller switches the first and second switches at least five times during the main capacitor discharging phase.

15 . The pulse power generator according to claim 14 , wherein, for each power stage:

the main capacitor includes a cathode connected to a positive input terminal and an anode connected to a negative input terminal;

the power stage includes a diode having an anode connected to the positive input terminal and a cathode connected to a positive output terminal; and

a negative output terminal is connected to a junction between the discharging and charging switches; and

the auxiliary capacitor is connected between the anode of the main capacitor and a cathode of the first switch.

16 . A method of controlling a power stage of a pulsed power generator, which includes:

an input power source;

a plurality of power stages, each comprising:

a half bridge based Marx generator power cell comprising:

a main capacitor connected between a positive input terminal and a negative input terminal; and

a main half bridge switch circuit connected in parallel with the main capacitor and configured to alternately set the power cell in a discharging phase or a charging phase;

a pulsating power buffer connected in a boost mode or a buck mode configuration and in parallel with the main capacitor, the pulsating power buffer comprising:

an auxiliary capacitor;

an inductor; and

an auxiliary half bridge switch circuit including first and second switches;

a voltage detector configured to detect a main voltage across the main capacitors; and

a controller,

the method comprising:

setting each power stage in a discharging phase using the controller including:

setting the main capacitor in a discharging phase including controlling the main half bridge switch to connect the main capacitor in series with the main capacitor of an adjoining power stage; and

setting the pulsating power buffer in a discharging phase including switching the first and second switches in a complementary manner when the main voltage is less than a threshold voltage to deliver a discharge current from the auxiliary capacitor through the inductor that supplements the main voltage; and

setting each power stage in a charging phase using the controller including:

setting the main capacitor in a charging phase including controlling the main half bridge switch to connect the main capacitor in parallel with the input power source; and

setting the pulsating power buffer in a charging phase including switching the first and second switches in a complementary manner when the main voltage is greater than a threshold voltage to deliver a charge current to the auxiliary capacitor through the inductor that increases a voltage across the auxiliary capacitor.

17 . The method according to claim 16 , wherein:

for each power cell, the main half bridge switch circuit comprises:

a discharging switch; and

a charging switch;

setting the main capacitor in the discharging phase includes closing the discharging switch and opening the charging switch; and

setting the main capacitor in the charging phase includes opening the discharging switch and closing the charging switch.

18 . The method according to claim 17 , wherein:

for each power stage, the pulsating power buffer is connected in the buck mode configuration, in which the auxiliary half bridge switch circuit is connected in parallel with the main capacitor;

setting the pulsating power buffer in the discharging phase comprises switching the first and second switches in a complementary manner to drive the discharge current from the auxiliary capacitor through the inductor and the first switch; and

setting the pulsating power buffer in the charging phase comprises switching the first and second switches in a complementary manner to drive the charge current through the first switch and the inductor to the auxiliary capacitor.

19 . The method according to claim 17 , wherein:

for each power stage, the pulsating power buffer is connected in the boost mode configuration, in which the inductor is connected in series between a cathode of the main capacitor and a junction between the first and second switches, the second switch is connected in parallel with the main capacitor and the first switch is connected in series between the junction and a cathode of the auxiliary capacitor;

setting the pulsating power buffer in the discharging phase comprises switching the first and second switches in a complementary manner to drive the discharge current from the auxiliary capacitor through the first switch and the inductor; and

setting the pulsating power buffer in the charging phase comprises switching the first and second switches in a complementary manner to drive the charge current through the inductor and the first switch to the auxiliary capacitor.

20 . The method according to claim 16 , wherein, switching the first and second switches in a complementary manner based on the main voltage to deliver the discharge current from the auxiliary capacitor through the inductor that supplements the main voltage comprises switching the first and second switches at least five times during the discharging phase of the main capacitor.