Methods and circuitry for fault detection and automatic equalizers for battery packs

Abstract

The present disclosure is directed to method of automatic circuit fault detection. The method includes inputting a common periodic wave voltage to each of a plurality of battery cells of a battery pack. Recursively calculated correlation coefficients for each neighboring pair of the battery cells are used to determine whether a common battery cell of two neighboring pairs is faulty. The disclosure further describes equalizers for multi-cell battery packs and series-connected battery strings. The equalizers can include a coupling capacitor comprising a plurality of small plates coupled between the two series-connected metal-oxide-semiconductor field-effect transistors (MOSFETs) connected to each battery cell, and a larger plate, wherein the larger plate is commonly coupled to all of the small plates. A plurality of battery string groups can be equalized, where each cell includes one transformer winding and a MOSFET. The MOSFETs are driven using one pair of complementary pulse width modulation signals.