Patent ID: 9608458
Date: 2017-03-28
CPC Classifications: H02J

Claim:
1. A method of pre-charging a plurality of series-connected battery modules, each battery module having one or more rechargeable battery cells, the method comprising: connecting a charging voltage source across the plurality of series-connected battery modules to cause a pre-charge current to flow in a pre-charge current path into the battery cells of the respective series-connected battery modules, each battery module having a buck pre-charging circuit including an inductor, the pre-charge current path at least initially passing through the inductor included in the buck pre-charging circuit of each battery module in order to allow the pre-charge current to induce a magnetic field within the inductor included in the buck pre-charging circuit of the battery module; in an interrupting step, once the pre-charge current has ramped up to a first threshold current value, interrupting the pre-charge current to initiate a collapse of the magnetic field within the inductor included in the buck pre-charging circuit of one or more of the plurality of series-connected battery modules, thereby causing one or more flyback currents to flow within the one or more series-connected battery modules, respectively, each flyback current flowing in a flyback current path that passes through the inductor included in the buck pre-charging circuit of a respective one of the one or more series-connected battery modules, the flyback current flowing from the inductor into the battery cells of the respective one of the one or more series-connected battery modules; in an allowing step, once the flyback current within at least one of the one or more series-connected battery modules has ramped down to a second threshold current value, allowing the pre-charge current to flow in the pre-charge current path into the battery cells of the respective series-connected battery modules; alternating between the interrupting step and the allowing step until the battery cells within each of the plurality of series-connected battery modules have been charged to at least a minimum voltage level needed for operation; and once the battery cells within each of the plurality of series-connected battery modules have been charged to at least the minimum voltage level needed for operation, causing, by the charging voltage source connected across the plurality of series-connected battery modules, a full-charge current to flow into the battery cells of the respective series-connected battery modules.