Design of 1000 V Valve Regulated Lead Acid (VRLA) and Lithium-Iron-Phosphate Lithium Ion (LFP-LI) Battery Test Beds for Driving High Rate, Pulsed Loads

A pulsed power system's intermediate energy storage typically requires charge voltages as high as tens to hundreds of kV. While these high charge voltages are easily obtained in the laboratory using utility grid-tied power supplies, they are not so easily generated aboard the future naval ships on which pulsed power systems will be deployed. One possible option being considered involves using high voltage electrochemical energy storage modules (ESMs) with open circuit potential (OCP) s as high as 1000 VDC to both power loads and buffer other onboard generation sources. A high switching frequency DC/DC converter can be used to transform the ESM's 1000 VDC voltage up to the charge voltage required of the pulsed power system's intermediate energy storage. While this seems simple, few have ever constructed and evaluated a 1000 VDC ESM since there are few, if any, commercial applications that would demand this voltage. In the work presented here, two-1000 VDC electrochemical batteries have been designed and constructed. The first is a valve regulated lead acid (VRLA) battery made up of two parallel connected strings of 75-12.5 V modules connected in series. The second is a lithiumiron-phosphate lithium-ion (LFP-LI) battery made up of 28-38 V modules (10S/1P) connected in series. Electromechanical relays are used to interconnect lower voltage modules into a single battery when operational. The relays also double as an operational safety that isolates modules in the event of improper battery operation. Control of these relays in fault isolation conditions is non-trivial and is of interest for study here. The transient nature of battery operation at high C rates will be characterized along with the battery's electrical performance, thermal properties, and usable capacity at high-pulsed rates of interest to naval applications.