| 1. |
- Qin, Haihong, et al.
(författare)
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A Comparative Study of Freewheeling Methods for eGaN HEMTs in a Phase-leg Configuration
- 2021
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Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - 2168-6777 .- 2168-6785. ; 9:3, s. 3657-3670
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Tidskriftsartikel (refereegranskat)abstract
- Enhancement Gallium nitride high-electron mobility transistors (eGaN HEMTs) have been developed with lower conduction losses and higher switching speed compared to MOSFETs. Self-commutated reverse conduction (SCRC) mechanism determines no reverse recovery phenomenon but larger reverse conduction voltage drop of eGaN HEMTs than the body diodes in traditional Si MOSFETs or other freewheeling diodes. To reduce the large reverse conduction loss of eGaN HEMTs, the performance of different freewheeling methods for eGaN HEMTs in a phase-leg configuration is compared in this paper. Firstly, the reverse conduction mechanism and characteristics of eGaN HEMTs are analyzed. Then, four freewheeling ways for eGaN HEMTs are introduced, and the equivalent circuits are also given and analyzed. A double pulse test platform is established to further explore the influence of the freewheeling ways on the conduction and switching characteristics. Finally, the total losses of a phase-leg configuration with different freewheeling ways based on a buck converter is analyzed and compared. The paper aims to give a guidance to properly select freewheeling ways for eGaN HEMTs under different operation conditions.
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| 2. |
- Qin, Haihong, et al.
(författare)
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Design of overvoltage suppression filter based on high-frequency modeling of cable in SiC based motor drive
- 2022
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Ingår i: Energy Reports. - : Elsevier BV. - 2352-4847. ; 8, s. 822-831
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Tidskriftsartikel (refereegranskat)abstract
- SiC-based motor drives have the advantages of achieving higher efficiency and higher power density than traditional Si-based motor drives, and are gradually being widely used in electric power transmission. Due to different application situations such as oil field and airplane, a long cable is applied between the motor drive and three-phase motor and the distance may exceed hundreds of meters, which will cause serious voltage reflection problem, damaging working life of the motor. Meanwhile, the high slew rate of output voltage created by SiC-based motor drive deteriorates this phenomenon. In order to solve this problem, we first analyze the principle and influencing factors of voltage reflection, and establish the equivalent circuit model of the long cable. Then we put forward design method of LRC passive filter to suppress voltage reflection, and give simulation analysis. At last we built an experimental platform to verify the effectiveness of the LRC passive filter in SiC-based motor drive, and the experimental results show that the LRC passive filter with optimized parameters has good suppression effect of voltage reflection.
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| 3. |
- Qin, Haihong, et al.
(författare)
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Evaluation and Suppression Method of Turn-off Current Spike for SiC/Si Hybrid Switch
- 2023
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Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 11, s. 26832-26842
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 4. |
- Qin, Haihong, et al.
(författare)
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Evaluation of antiparallel SiC Schottky diode in SiC MOSFET phase-leg configuration of synchronous rectifier
- 2023
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Ingår i: Energy Reports. - 2352-4847. ; 9, s. 337-342
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Tidskriftsartikel (refereegranskat)abstract
- The MOSFET synchronous rectification (SR) is widely used to reduce the conduction loss during the freewheeling period. Due to the wide band gap of silicon carbide (SiC), the intrinsic body diode of SiC MOSFET exhibits a high voltage drop. Therefore, SiC Schottky diodes (SBD) and SiC MOSFETs are usually used in reverse parallel to reduce power loss. However, the increase of equivalent junction capacitance due to the addition of an external SiC SBD could bring larger turn-on current on opposite power transistor of the phase-leg. Furthermore, as the parasitic inductance associated with layout hinders the prompt transfer of current between SiC SBD and body diode, the external SiC SBD cannot be fully utilized, and it may deteriorate the overall performance, especially at heavy load. We comprehensively compare power losses when SiC SBD are antiparallel or not, at different working conditions, including different layout compactness, load current and dead time. It's hard to get the effect of loss reduction loss when add antiparallel SiC SBD due to the parasitic inductance induced by the layout. The results can provide a guidance to properly select SiC SBD in a phase-leg configuration under SR mode for freewheeling during the dead time.
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