Current Measurement Issues of a High Frequency GaN Inverter in the MHz Order for Magnetic Characterization

Abstract

Nowadays, there is a great interest in the industry for outstanding magnetic materials with low-loss properties. Moreover, with the introduction of novel Wide Bandgap devices, higher frequency operation has been demanded from these novel magnetic materials. Thereby, magnetic characterization for obtaining the iron loss behavior is essential. However, when a magnetic material is experimentally characterized, it is important to select a suitable measurement device, especially when a semiconductor inverter is powering the magnetic material and it is driven at a high switching frequency. Usually measurement devices have a good response in magnitude, but there is not a clear understanding about how their phase response at high frequencies measurements affects the characterization. Consequently, if the phase characteristics of a measurement device is not well-know, it is likely that the iron loss characterization will not be accurate. This paper studies the measurement issues when an iron loss characterization procedure is conducted. This study is carried out with the comparison of using clamp type current probes and high precision shunt resistors at high switching frequency excitations with a GANFET inverter. In addition, an experimental evaluation of iron losses at several switching frequencies is presented. As a result, the phase characteristics of several sensors was obtained, and it was possible to identify the inaccuracies that they can generate at a high frequency measurement.