公开(公告)号：US11233475B2

公开(公告)日：2022-01-25

申请号：US16874017

申请日：2020-05-14

Applicant: Rockwell Automation Technologies, Inc.

Inventor： James J Valasek ,  Nickolay Guskov ,  Gary Skibinski

IPC: H02P27/04 ,  H02M5/42

Abstract: A precharge system for precharging a DC bus circuit includes a first input, first and second circuit branches, and a controller, where the first circuit branch includes a first contactor between the first input and an AC to DC converter, the second circuit branch has: a disconnect switch coupled to the first input; a variable frequency drive (VFD) with an AC input coupled to the disconnect switch; an inductor coupled to an AC output of the VFD; and a second contactor coupled to the inductor. The precharge VFD provides precise control of the precharge operation such as charging time, current limiting, short-circuit and ground fault protection, monitoring DC Bus capacitance and verifies the health of the shared DC bus circuit through startup diagnostic. The controller opens the first contactor and closes the second contactor and the disconnect switch in a first mode to precharge the DC bus circuit using the VFD, and in a second mode, the controller closes the first contactor and opens the second contactor and the disconnect switch.