A high efficient synchronous rectifier for next generation automotive alternator applications

For the demand of new energy vehicles, the market is driving the car brands especially in European Union, China and the United States, and their tier suppliers to develop the key components of the powertrain and electric systems for 12V micro-hybrid (start-stop) and 48V mild-hybrid electric vehicles. An automotive-grade synchronous rectifier composed of Si Power MOSFET and gate driver was developed to replace the conventional rectifer diodes for the improvement of the efficiency of AC-DC converting. Two synchronous rectifier modules were then integrated with an alternator system, the efficiency of AC-DC converting was found as high as 97% and the efficiency of the alternator system was determined to be 78%. The synchronous rectifier has been qualified the automotive-grade reliability tests including temperature cycling test (TCT), highly accelerated stress test (HAST), high temperature reverse bias (HTRB) and power cycling test (PCT) according to the AEC-Q101 standard, and could be adopted for the applications of 12V start-stop system and 48V belt-alternator starter generator (BSG) systems.