April/May 2021

www.gansystems.com AUTOMOTIVE POWER 27 www.power-mag.com Issue 2 2021 Power Electronics Europe promising power semiconductors set to improve overall efficiency and meet future demands of EV powertrains. Table 1 shows GaN, SiC, Si MOSFET, and Si IGBT comparisons. The GaN transistor shows some impressive advantages: Zero reverse recovery charger (Q rr ): for hard commutation topology such as a totem pole PFC and a traction inverter, the larger Q rr for Si MOSFET and Si IGBT’s anti- parallel diode bring a large turn-on loss on the transistors, thus limiting the switching frequency and efficiency improvements. GaN’s zero Q rr means lower switching loss which is ideal for OBCs and traction inverters. Especially in OBC topology, the totem pole PFC with GaN transistors can achieve high efficiency and bi-directional operation. A SiC MOSFET also shows fairly lower Q rr compared to Si. But at high temperature with its intrinsic bipolar body diode characteristics, the SiC MOSFET also has switching losses due to Q rr , which limits the switching frequency improvement for the OBC and traction inverter, impeding further power density and weight improvements. Switching speed: GaN transistors allow fast switching with lower switching turn-on and turn-off losses, so it is extremely effective to reduce the volume and weight for some passive components, such as OBC and DC/DC inductors and transformers. For the traction inverter, the higher switching frequency is also favorable because it results in reduced THD of the motor current at high RPM. Low Q g and Q oss : GaN transistors show very low gate charge (Q g ) and output charge (Q oss ). These values are important for soft switching Zero Voltage Switching (ZVS) achievement on soft switching topology, such as an OBC’s CLLC converter. With lower Q oss and Q g , ZVS operation is easier to achieve without a large magnetizing current on the transformer. Also, it is evident that GaN transistors can increase the operating frequency range to support a wide output battery range for an OBC’s CLLC topology. All of these parameters demonstrate that GaN is an optimal choice with respect to high power density, high efficiency, and system cost. GaN transistors are being implemented more and more in EV powertrain systems which highlight confidence in its reliable outperformance and benefits on system cost, density, efficiency, and weight. Examples of OBC, DC/DC converter, and traction inverter products that demonstrate the GaN’s high performance advantages according to Table 2. To receive your own copy of Power Electronics Europe subscribe today at: www.power-mag.com E-CAMPAIGN LIST RENTAL LEASE Di rect C ontact: Ian Akinson on t: +44 (0) 1732 370340 e: ian.atkinson@dfamedi a.co.uk TARGET YOUR BUYERS FROM OVER 60,000 QUALIFIED CONTACTS