A Compact High Current System for Short Circuit Testing of Smart Power Switches According to AEC Standard Q 100-012

摘要

The short circuit robustness of smart power switches has become a major concern in automotive applications over the last years. This is reflected in a new extension to the AEC qualification standard Q100-12, where the basic requirements for short circuit testing of "smart" switches with integrated overcurrent protection are given. This paper describes the practical implementation of a compact test setup for the laboratory measurement of short circuit events with initial peak currents as high as 1000A at supply voltages up to 60V. The AEC standard further requires a low-ohmic test circuit with well-defined impedances. This is usually achieved by arrangement of a large DC power supply with discrete copper bus bars, massive test fixtures and solenoid type air coils to achieve well-defined resistance and inductance values. Our novel approach utilizes a compact printed circuit board arrangement instead, replacing large copper cross sections by short distances and optimized geometries to achieve the same performance at a fraction of the cost and space requirements. To protect the equipment from potential hazard of fire in case of a destructive device failure without sacrificing performance, fast overcurrent detection is required as well as shutdown and removal of energy from the tested device within microseconds. This can be achieved with low-cost off-the-shelf current sensors and surface-mounted MOSFET switches by careful consideration of their specified properties. Representative measurements of industry standard high current smart power switches show that the presented test equipment meets the requirements of Q100-12 for laboratory short circuit measurements.