US 12,313,698 B2
Method for self-testing of a phase of a 3-level ANPC converter with LC filter
Uwe Stickelmann, Kaufungen (DE)
Assigned to SMA Solar Technology AG, Niestetal (DE)
Filed by SMA Solar Technology AG, Niestetal (DE)
Filed on Feb. 22, 2023, as Appl. No. 18/172,358.
Application 18/172,358 is a continuation of application No. PCT/EP2021/073996, filed on Aug. 31, 2021.
Claims priority of application No. 10 2020 122 770.1 (DE), filed on Sep. 1, 2020.
Prior Publication US 2023/0194626 A1, Jun. 22, 2023
Int. Cl. G01R 31/42 (2006.01); H02M 7/537 (2006.01)
CPC G01R 31/42 (2013.01) [H02M 7/537 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for testing an inverter having a bridge, comprising:
a first switch arranged between a positive connection of a divided link circuit having a center point and a positive inner connection,
a second switch arranged between the positive inner connection and a bridge output,
a third switch arranged between the bridge output and a negative inner connection,
a fourth switch arranged between the negative inner connection and a negative connection of the divided link circuit,
a fifth switch arranged between the center point and the positive inner connection, and
a sixth switch arranged between the center point and the negative inner connection,
wherein a grid filter with a filter inductor and a filter capacitor is connected to the bridge output,
wherein the method comprises:
applying a link circuit voltage to the divided link circuit, while the bridge output with a connected mains filter is isolated from a connected grid,
discharging the filter capacitor,
closing the first switch and the sixth switch, while the fourth switch and the fifth switch are open,
subsequently clocking the second switch using a plurality of short pulses, wherein a duty cycle of the pulses is set between 1% and 5%,
after clocking, determining a voltage dropped across the filter capacitor, and
identifying a fault state of the bridge when the dropping voltage is outside a voltage window with an upper window limit and a lower window limit.