Design and Implementation of Integrated Common Mode Capacitors for SiC-JFET Inverters

Abstract

Abstract-This paper deals with the issue of electromagnetic interference (EMI) in SiC-JFET inverter power modules, and proposes a solution to limit conducted emissions at high frequencies. SiC-JFET inverters can achieve very fast switching, thereby reducing commutation losses, at the cost of a high level of EMI. In order to limit conducted EMI emissions, it is proposed to integrate small-value common mode (CM) capacitors, directly into the power module. High frequency noise, which is usually difficult to filter, is then contained within the module, thus keeping it far from the external network. This approach is in line with the current trend towards the integration of various functions (such as protection, sensors or drivers) around power devices in modern power modules. To demonstrate this concept, the resulting CM noise was investigated, and compared with a standard configuration. Simulations were used to design the integrated capacitors, and measurements were carried out on an experimental SiC-JFET half-bridge structure. A significant reduction was achieved in the experimentally observed CM conducted emissions, with a very minor influence on the switching waveforms, losses and overall size of the system. The benefits and limitations of this design are discussed, for the case of mid-power range inverters for aircraft applications.

Using Current Surface Probe to Measure the Current of the Fast Power Semiconductors

“…8. It can be seen that the insertion impedance (equivalent to L para ) induced in the measurement power circuit when using CS is about 14 nH (which is mainly due to the connection pins and internal parasitic inductance of the CS itself [17], [23]), and when using CSP together with the PCB is about 4.5 nH. These results show that the use of the CSP brings even less L para in the measurement circuit than CS.…”

“…3) CS: It is nowadays widely used for fast switching current measurement. Authors in [10], [16], and [17] used the CS to measure SiC-JFET and GaN-HEMT switching current. The advantage of the CS is that it has a large bandwidth (above 1 GHz), which makes it totally adapted for the fast switch power semiconductors.…”

“…This drawback also introduces a hard-to-be-controlled common mode loop of the circuit (modification of the circuit potentials and the common mode current paths), which may influence the measurement results. It can be also noted that there is no isolation between the CS and the oscilloscope and its insertion impedance can vary from several to more than a dozen nH according to different models [16], [17]. Besides that, the heating can become also a problem of the CS [18].…”

Applications, Prospects and Challenges of Silicon Carbide Junction Field Effect Transistor (SIC JFET)

“…The mechanism is built for space crafts. The work reported in [34], dealt with electromagnetic interference in a SiC JFET inverter. It proposed integrating small-value common-mode (CM) capacitors into the inverter so as to minimize EMI.…”

A Comparative Evaluation of SiC Power Devices for High-Performance Domestic Induction Heating

“…In particular, new wide band-gap power devices, with silicon carbide (SiC) as the most mature technology, enables a new design paradigm with improved levels of efficiency and performance [18][19][20][21][22][23][24]. Among the benefits of the different SiC power devices, the following ones perfectly match IH requirements:…”