US 12,424,838 B2
Safety device for an electric DC grid, onboard electrical system for a vehicle, vehicle, and DC charging station
Urs Boehme, Ehningen (DE)
Assigned to MERCEDES-BENZ GROUP AG, Stuttgart (DE)
Appl. No. 18/292,373
Filed by MERCEDES-BENZ GROUP AG, Stuttgart (DE)
PCT Filed Jul. 26, 2022, PCT No. PCT/EP2022/070890
§ 371(c)(1), (2) Date Jan. 26, 2024,
PCT Pub. No. WO2023/006715, PCT Pub. Date Feb. 2, 2023.
Claims priority of application No. 10 2021 003 830.4 (DE), filed on Jul. 27, 2021.
Prior Publication US 2025/0079826 A1, Mar. 6, 2025
Int. Cl. H02H 3/26 (2006.01)
CPC H02H 3/26 (2013.01) 7 Claims
OG exemplary drawing
 
1. A safety device for an electric DC grid, the safety device comprising:
a first voltage measuring device arranged between a positive potential line and a reference potential line and configured to measure a voltage between the positive potential line and the reference potential line;
a second voltage measuring device arranged between a negative potential line and the reference potential line and configured to measure a voltage between the negative potential line and the reference potential line,
a protective circuit configured to reduce an electric shock caused by Y-capacitors of the electric DC grid, wherein the protective circuit comprises
a first circuit breaker between the positive potential line and the reference potential line; and
a second circuit breaker between the negative potential line and the reference potential line,
wherein a plurality of tripping criteria are predefined and the first circuit breaker or the second circuit breaker is actuatable so as to close exclusively in event of all predefined tripping criteria being met as determined by the first voltage measuring device or the second voltage measuring device,
wherein the tripping criteria comprise
a voltage deviation of a voltage applied between the positive potential line and the reference potential line and a voltage applied between the negative potential line and the reference potential line from a previously determined voltage value,
a voltage changes in the voltage applied between the positive potential line and the reference potential line and the voltage applied between the negative potential line and the reference potential line,
the voltage applied between the positive potential line and the reference potential line is of the opposite sign to the voltage applied between the negative potential line and the reference potential line, and
an absence of a cyclical repetition of other tripping criteria, wherein the first circuit breaker or the second circuit breaker are actuatable only if
the voltage deviation of the voltage present between the positive potential line and the reference potential line and the voltage present between the negative potential line and the reference potential line from the previously determined voltage value exceeds a predefined limit value, and
the voltage changes of the voltage applied between the positive potential line and the reference potential line and the voltage applied between the negative potential line and the reference potential line exceeds a predefined limit value, and
the voltage applied between the positive potential line and the reference potential line and is of the opposite sign to the voltage applied between the negative potential line and the reference potential line, and
if the absence of the cyclical repetition of the other tripping criteria is determined.