Solid-State High Common-Mode Battery Cell Voltage Scanner: Design Report

摘要

The characterization or testing of full-size electric-vehicle batteries using a computerized data acquisition system (DAS) poses three major problems. The first problem is one of discrimination. Common-mode voltages approaching 300 V are routinely encountered and must be safely rejected by the DAS while it is accurately recording individual cell voltages, which are low in comparison to common-mode voltages. The second problem involves reduction of the data collected, and the third concerns protection of the battery under test. The continuous-scan solid-state instrument described in this report addresses these problems. The micro-processor-based instrument, which is interfaced to a computer automated measurement and control (CAMAC) system, has the ability to reject common-mode voltages of up to 300 V. It incorporates data-reduction algorithms to minimize the amount of data passed to a central computer through the CAMAC system. This data-reduction feature also simplifies statistical cell studies by providing (1) minimum and maximum cell voltages, (2) identification of cells producing the minimum and maximum voltages, and (3) the average and the standard deviation of the cell voltages. The instrument provides battery system protection by comparing the individual cell voltages to preset minimum and maximum limits and signaling any deviations. The scanner can be programmed to signal any cell voltage irregularity or to automatically terminate the testing should deviations occur.