Power electronic building block for modular multilevel converters

1 . A power electronic building block (PEBB), comprising:

a plurality of capacitors;

a plurality of switch modules, each switch module of the plurality of switch modules including a first terminal, a second terminal and a third terminal, at least one first semiconductor switch connected between the first terminal and the third terminal, and at least one second semiconductor switch connected between the second terminal and the third terminal;

a busbar arrangement including one or more busbars connecting the first terminals of the plurality of switch modules together, connecting the second terminals of the plurality of switch modules together, and connecting the plurality of capacitors in parallel across the first terminals and the second terminals of the plurality of switch modules, via a first plurality of connection points, wherein the busbar arrangement includes a capacitor busbar configured to connect the plurality of capacitors in parallel, and a switch busbar connected to the capacitor busbar configured to connect the plurality of capacitors in parallel across the first terminals and the second terminals of the plurality of switch modules; and

at least one AC busbar including a second plurality of connection points connecting the third terminals of the plurality of switch modules together via said at least one AC busbar, and at least one AC terminal point,

wherein the second plurality of connection points of the at least one AC busbar are arranged symmetrically along a first direction with respect to a plane perpendicularly intersecting the first direction, and

wherein the at least one AC busbar includes a hole elongated along the first direction and configured to balance one or more loop inductances between the at least one AC terminal point and the second plurality of connection points.

2 . The PEBB according claim 1 , further including a DC crowbar thyristor and clamping apparatus connected in parallel with the plurality of capacitors.

3 . The PEBB according to claim 1 , including at least two AC busbars, and further including a bypass switch connected across said at least two AC busbars.

4 . The PEBB according to claim 1 , wherein the one or more busbars of the busbar arrangement are laminated busbars.

5 . The PEBB according to claim 1 , wherein the PEBB is of a half-bridge type, where the plurality of switch modules forms a single group of switch modules, and wherein the at least one AC busbar includes a first AC busbar connecting the third terminals of the plurality switch modules together and a second AC busbar connected to the first or second terminals of the plurality of switch modules.

6 . The PEBB according to claim 1 , wherein the PEBB is of a full-bridge type, where the plurality of switch modules are divided into a first group of switch modules and a second group of switch modules, and wherein the at least one AC busbar includes a first AC busbar connecting the third terminals of the first group of switch modules together and a second AC busbar connecting the third terminals of the second group of switch modules together.

7 . The PEBB according to claim 1 , wherein the plurality of capacitors is a plurality of can type film capacitors.

8 . The PEBB according to claim 7 , wherein the capacitor busbar includes the hole elongated along the first direction and configured to balance one or more loop inductances within the capacitor busbar.

9 . The PEBB according to claim 7 , wherein the capacitor busbar has a U-shape, and wherein the plurality of capacitors is provided on both sides of one end of said U-shape.

10 . The PEBB according to claim 1 , wherein the plurality of capacitors is a plurality of box type film capacitors.

11 . A modular multilevel converter, MMC, including a plurality of converter arms, each converter arm including at least one sub module formed by a PEBB according to claim 1 .

12 . A power electronic building block (PEBB), comprising:

a plurality of capacitors;

a plurality of switch modules, each switch module of the plurality of switch modules including a first terminal, a second terminal and a third terminal, at least one first semiconductor switch connected between the first terminal and the third terminal, and at least one second semiconductor switch connected between the second terminal and the third terminal;

a busbar arrangement including one or more busbars connecting the first terminals of the plurality of switch modules together, connecting the second terminals of the plurality of switch modules together, and connecting the plurality of capacitors in parallel across the first terminals and the second terminals of the plurality of switch modules, via a first plurality of connection points, wherein the busbar arrangement includes a capacitor busbar configured to connect the plurality of capacitors in parallel, and a switch busbar connected to the capacitor busbar configured to connect the plurality of capacitors in parallel across the first terminals and the second terminals of the plurality of switch modules;

at least one AC busbar including a second plurality of connection points connecting the third terminals of the plurality of switch modules together via said at least one AC busbar, and at least one AC terminal point,

wherein the second plurality of connection points of the at least one AC busbar are arranged symmetrically along a first direction with respect to a plane perpendicularly intersecting the first direction, and

wherein the at least one AC busbar includes a hole elongated along the first direction and configured to balance one or more loop inductances between the at least one AC terminal point and the second plurality of connection points; and

a DC crowbar thyristor and clamping apparatus connected in parallel with the plurality of capacitors, wherein the busbar arrangement further includes a clamp busbar connected to the capacitor busbar configured to connect the DC crowbar thyristor and clamping apparatus in parallel with the plurality of capacitors.

13 . A power electronic building block (PEBB), comprising:

a plurality of box type film capacitors;

a plurality of switch modules, each switch module of the plurality of switch modules including a first terminal, a second terminal and a third terminal, at least one first semiconductor switch connected between the first terminal and the third terminal, and at least one second semiconductor switch connected between the second terminal and the third terminal;

a busbar arrangement including one or more busbars connecting the first terminals of the plurality of switch modules together, connecting the second terminals of the plurality of switch modules together, and connecting the plurality of capacitors in parallel across the first terminals and the second terminals of the plurality of switch modules, via a first plurality of connection points, wherein the busbar arrangement includes a capacitor busbar configured to connect the plurality of capacitors in parallel, a main busbar connected to the capacitor busbar, and a switch busbar connected to the main busbar for connecting the plurality of capacitors in parallel across the first terminals and the second terminals of the plurality of switch modules via said main busbar; and

at least one AC busbar including a second plurality of connection points connecting the third terminals of the plurality of switch modules together via said at least one AC busbar, and at least one AC terminal point,

wherein the second plurality of connection points of the at least one AC busbar are arranged symmetrically along a first direction with respect to a plane perpendicularly intersecting the first direction, and

wherein the at least one AC busbar includes a hole elongated along the first direction and configured to balance one or more loop inductances between the at least one AC terminal point and the second plurality of connection points.

14 . The PEBB according to claim 13 , further including a DC crowbar thyristor and clamping apparatus connected in parallel with the plurality of capacitors, wherein the main busbar is further configured for connecting the DC crowbar thyristor clamp in parallel with the plurality of capacitors.