This study examines the impact of the different diode characteristics on the magnetic hysteretic and iron loss properties of a conventional non-oriented (NO) silicon steel sheet core under silicon carbide (SiC) inverter excitation. We compared the magnetic properties of the magnetic core excited by the inverter using the developed Schottky barrier diode (SBD) wall-integrated trench MOSFET (SWITCH–MOS), which has a low on-voltage Von diode, with those excited by the inverter using a conventional U-shaped trench gate MOSFET (UMOS), which has a body PiN diode with high Von. This study shows for the first time that the shape of the minor loop and iron loss properties depends strongly on only the diode characteristics in the inverter. The iron loss of magnetic materials excited by the SWITCH–MOS inverter with the low-Von diode (i.e., the built-in SBD) was less than that in the case of using the conventional UMOS with a high-Von diode (i.e., the body PiN diode). That is, the SWITCH–MOS with built-in SBD can reduce not only the switching loss, but also the iron loss in magnetic materials such as motor cores.