Reducing switching losses in BLDC motor drives by reducing body diode conduction of MOSFETs

This paper focuses on switching losses in hard switched converters. More specifically, on reverse conduction losses of MOSFET intrinsic body diodes as employed in BLDC motor drive inverter circuits. Synchronous rectification (SR) has been extensively implemented in low-voltage switch-mode dc/dc power conversion to reduce diode conduction losses. Extending the benefits of SR to high-voltage applications requires careful attention to the reverse conduction behavior of the synchronous rectifier MOSFET´s intrinsic body diode. The proposed technique for reducing body diode conduction is to add a MOSFET back-to-back, in series with the rectifying switch, and a Schottky or SiC type diode around the series switch combination. This research builds on previous patented work in which the proposed technique is used in low voltage dc-dc converter applications. This new work focuses on higher voltage motor drive applications.