SiC and GaN power transistors switching energy evaluation in hard and soft switching conditions

SiC and GaN power transistors switching energy are compared in this paper. In order to compare switching energy Esw of the same power rating device, a theoretical analysis is given to compare SiC device conduction loss and switching losses change when device maximal blocking voltage reduces by half. After that, Esw of a 650V GaN-HEMT is measured in hard switching condition and is compared with that of a 1200V SiC-MOSFET and a 650V SiC-MOSFET with the same current rating, in which it is shown that Esw of a GaN-HEMT is smaller than a 1200V SiC-MOSFET, which is smaller than 650V SiC-MOSFET. Following by that, in order to reduce device turn-ON switching energy, a zero voltage switching circuit is used to evaluate all the devices. Device output capacitance stored energy Eoss are measured and turn-OFF switching losses are obtained by subtracting Eoss, which shows that GaN-HEMT is sill better than SiC device in terms of switching losses and 1200V SiC-MOSFET has smaller switching losses than 650V SiC-MOSFET

SiC/GaN power semiconductor devices: a theoretical comparison and experimental evaluation under different switching conditions

The conduction and switching losses of SiC and GaN power transistors are compared in this paper. Voltage rating of commercial GaN power transistors is less than 650V while that of SiC power transistors is less than 1200V. The paper begins with a theoretical analysis that examines how the characteristics of a 1200V SiC-MOSFET change if device design is re-optimised for 600V blocking voltage. Afterwards, a range of commercial devices (1200V SiC-JFET, 1200V SiC-MOSFET, 650V SiC-MOSFET and 650V GaN-HEMT) with the same current rating are characterised experimentally and their conduction losses, inter-electrode capacitances and switching energy Esw are compared, where it is shown that GaN-HEMT has smaller ON-state resistance, inter-electrode capacitance values and Esw than SiC devices. Finally, in order to reduce device Esw, a zero voltage switching circuit is used to evaluate all the devices, where device only produces turn-OFF switching losses and it is shown that GaN-HEMT has less switching losses than SiC device in this soft switching mode. It is also shown in the paper that 1200V SiC-MOSFET has smaller conduction and switching losses than 650V SiC-MOSFET

Device loss model of a fully SiC based dual active bridge considering the effect of synchronous rectification and deadtime

It is becoming a great interest to employ SiC based power devices in dual active bridge (DAB) converter as an alternative to conventional Si-IGBT, due to its higher switching frequency potential, smaller switching losses as well as the capability to operate at synchronous rectification (SR) condition. This paper introduces the device loss model of a SiC MOSFET power module based DAB converter considering the effect of synchronous rectification, and the dead-time effect is also discussed. The calculated device loss for both SiC-MOSFET and Si-IGBT are discussed. The results show that the overall device loss is reduced by 40%, where the conduction loss is reduced by 38% because of SR capability of SiC-MOSFET, and the switching loss is reduced by 48% due to the faster transient of SiC-MOSFET during dead-time. On the other hand, the device losses are not even between the primary bridge and the secondary bridge of the DAB converter, and it is more significant for SiC-MOSFET based DAB due to the effect of SR with a maximum of 20%. At last, the dead-time range is given based on the device properties

Impedance-Oriented Transient Instability Modeling of SiC MOSFET Intruded by Measurement Probes

Due to the breakneck switching speed, SiC mosfet is extremely sensitive to parasitics in the power device, circuit layout, and also measurement probe. It is not clear how the parasitics of measurement probes affect the transient stability of SiC mosfet, and it poses an unsolved challenge for the industrial field. This paper focuses to uncover the transient instability mechanism of SiC mosfet intruded by probes. Mathematical and circuit models of voltage and current probes are created, by considering the parasitics, input impedance, and bandwidth issues. To reveal the stability principles of SiC mosfet associated with probes, impedance-oriented and heterogeneity-synthesized models combining device with probes are proposed. Furthermore, an assessment methodology and root locus analysis are presented to demonstrate the transient stability schemes and the stable boundaries of SiC mosfet influenced by multiple factors, including probe parasitics, device parameters, gate resistances, and snubber circuits. Comparative experiments are presented to confirm the transient behaviors of SiC mosfet intruded by probe parasitics and regulated by control circuits. It is proven that, because of low bandwidth specifications, the large input capacitance of the voltage probe and coil inductance of the current probe degrade the transient stability of SiC mosfet. Due to the deteriorated stability margin of SiC mosfet intruded by the inserted parasitics of probes, instability may also be activated by using the small gate resistance. The snubber circuit is helpful to enhance the transient stability. Advanced probes with high bandwidth and high impedance are crucially needed for stable measurement of wide bandgap power devices like SiC mosfet.Ministry of Education (MOE)Nanyang Technological UniversityThis work was supported in part by the National Natural Science Foundation of China under Grant 51607016, in part by the National Key Research and Development Program of China under Grant 2017YFB0102303, in part by Singapore ACRF Tier 1 Grant RG 85/18, and in part by the NTU Startup Grant (SCOPES) for Prof Zhang Xin

Evaluation and Suppression Method of Turn-off Current Spike for SiC/Si Hybrid Switch

SiC MOSFET/Si IGBT (SiC/Si) hybrid switch usually selects the gate control pattern that SiC MOSFET turns on earlier and turns off later than Si IGBT, with the aim of making the hybrid switch show excellent switching characteristics of SiC MOSFET and reduce switching loss. However, when SiC MOSFET turns off, the fast slew rate of drain source voltage causes the current spike in Si IGBT due to the effects of parasitic capacitance charging and carrier recombination, which will produce additional turn-off loss, thus affecting the overall efficiency and temperature rise of the converter. Based on the double pulse test circuit of SiC/Si hybrid switch, the mathematical model of the turn-off transient process is established. The effects of the remnant carrier recombination degree of Si IGBT, the turn-off speed of SiC MOSFET and the working conditions on the turn-off current spike of hybrid switch are evaluated. Although adjusting these parameters can reduce the turn-off current spike somewhat, additional losses will be introduced. Therefore, a new method to suppress the turn-off current spike is proposed to balance the power loss and current stress

Représentation d'état pour un MOSFET SiC

International audienceThis paper proposes a State Space Model for a power a Silicon Carbide (SiC) MOSFET. The model uses the electrical EKV MOSFET structure. The model is developed for the SiC MOSFET CMD CREE (V, A) and uses the parameters extracted from datashee

Impact of SiC technology in a three-port active bridge converter for energy storage integrated solid state transformer applications

Silicon Carbide (SiC) MOSFET power module has become commercially available in the past few years, and it is attractive in solid state transformers (SSTs) applications to replace Silicon (Si)-based IGBTs. This paper is focused on the efficiency comparison between a SiC MOSFET-based three-port active bridge converter (TAB) and a Si IGBT-based approach. The efficiency of the overall system, being one of its ports connected to the energy storage element (Lithium-Ion battery), is tested and analyzed. By swapping the switching frequency of the device, a significant efficiency improvement can be observed by SiC power devices. Experimental results indicated that an efficiency increment of around 2% can be brought by SiC MOSFET. Moreover, the battery losses can be reduced by a maximum of 8% with the increased switching frequency

Electro-thermal Model of a Silicon Carbide Power MOSFET

International audienceThis paper proposes an electro thermal model for power silicon carbide (SiC) MOSFET based on the EKV MOSFET structure. The thermal dissipation is modeled as an RC Network. The model is developed for the SiC MOSFET CMD CREE (V, A) and integrated in the Psim, Saber and Pspice simulation software libraries for prototyping. The simulation curves are compared with the manufacturers' data-sheet

Parameters Design and Optimization of SiC MOSFET Driving Circuit with Consideration of Comprehensive Loss and Voltage Stress

In conventional parameters design, the driving circuit is usually simplified as an RLC second-order circuit, and the switching characteristics are optimized by selecting parameters, but the influence of switching characteristics on the driving circuit is not considered. In this paper, the insight mechanism for the gate-source voltage changed by overshoot and ringing caused by the high switching speed of SiC MOSFET is highlighted, and we propose an optimized design method to obtain optimal parameters of the SiC MOSFET driving circuit with consideration of parasitic parameters. Based on the double-pulse circuit, we evaluated the influence of main parameters on the gate-source voltage, including driving voltage, driving resistance, gate parasitic inductance, and stray inductance of the power circuit. A SiC-based boost PFC is constructed and tested. The test results show that the switching loss can be reduced by 7.282 W by using the proposed parameter optimization method, and the over-voltage stress of SiC MOSFET is avoided

Design and implementation of a modular bidirectional switch using SiC-MOSFET for power converter applications

Tis paper presents a novel modular design of a Bi-Sw with the purpose of providing to beginner researchers the key issues to design a power converter. Te Bi-Sw has been designed in modular form using the SiC-MOSFET device. Te Bi-Sw uses the advantages of SiC-MOSFET to operate at high switching frequencies. Te verifcation of the module is carried out experimentally by means of the implementation in a voltage regulating converter, where performance analysis, power losses, and temperature dissipation are performed.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI