Highly Repeatable Micro-Ohm Sensitive Resistance Measuring Fixture for Welded Sense Leads in High Voltage Battery Applications
Publication Date: 2015-Mar-12
The IP.com Prior Art Database
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Highly Repeatable Micro-Ohm Sensitive Resistance Measuring Fixture for Welded Sense Leads in High Voltage Battery Applications.
An extremely low noise and highly repeatable weld testing fixture design has been invented for use with a 4-terminal micro-Ohmmeter (resolution 0.1 micro-Ohms or better), producing and accepting minimal EMI (electromagnetic interference) in the captured voltage or calculated resistance.
Typically, wire or tape sense lead terminations to a highly conductive busbar in high voltage (HV) battery applications involve a planar or low profile weld joint as shown in Figure 1. These sense leads are used for multiple functions, including monitoring voltage, calculating state of charge (SOC), and monitoring battery charge or discharge cycles. For both high volume manufacturing and initial run-off / in-process samples, a repeatable measurement of weld included resistance is most often required to establish statistical process control (SPC). Due to the inability to measure the resistance of the weld itself, a certain amount of material will generally be included on both sides of the joint. The probe point pairs must be kept spatially common and accurate to facilitate reliable measurements, as even slight point position variation can cause a significant change in measured value at extremely low resistances. When the measuring points have been determined, a maximum allowable resistance for a given fixed testing procedure may then be specified by OEM/supplier to identify and isolate poor performing electrical welds.
The fixture design shown in Figure 1 accomplishes both a 4- terminal connection and a welded busbar datum locating feature simultaneously. The 4-terminal inpu...