In Voltage Source Inverter based motor drives, the fast switching speeds of the power devices result in the reflected wave phenomenon. The over-voltages increase stress on the motor and cable insulation, the over-currents affect the power devices. However, the reflected wave phenomenon is more pronounced in converters using wide bandgap devices and could potentially increase the switching losses. This paper studies the effect of undamped reflected waves and different cable lengths on both the inverter end and motor end are studied. The analysis and experiments in this paper uncovered that depending on the switching instance, the undamped reflected wave causes up to 30% increase or up to 15% decrease in the switching losses. A 12% reduction in the switching losses is observed with no cable to gradually increase the length of cable to 20 m. Five different dv/dt filters are compared in terms of their impact on the switching losses, dv/dt at the load, filter loss and damping time of the reflected wave. Overall L // R filter offers the lowest filters losses with 6% reduction in switching loss making it more suitable for wide bandgap devices based high-speed motor drives.

The electric propulsion drives for the more-electric aircraft need lightweight and high-efficiency power converters. Moreover, a modular approach to the construction of the drive ensures reduced costs, reliability, and ease of maintenance. In this article, the design and fabrication procedure of a modular dc–ac three-level t-type single phase-leg power electronics building block (PEBB) rated for 100-kW, 1-kV dc-link is reported for the first time. A hybrid switch (HyS) consisting of a silicon insulated-gate bipolar junction transistor (IGBT) and silicon carbide metal–oxide–semiconductor field-effect transistor (MOSFET) was used as an active device to enable high switching frequencies at high power. The topology and semiconductor selection were based on a model-based design tool for achieving high conversion efficiency and lightweight. Due to the unavailability of commercial three-level t-type power modules, a printed circuit board (PCB) and off-the-shelf discrete semiconductor-based high-power switch was designed for the neutral-point clamping. Also, a nontrivial aluminum-based multilayer laminated bus bar was designed to facilitate the low-inductance interconnection of the selected active devices and the capacitor bank. The measured inductance indicated symmetry of both current commutation loops in the bus bar and value in the range of 28–29 nH. The specific power and volumetric power density of the block were estimated to be 27.7 kW/kg and 308.61 W/in ³ , respectively. The continuous operation of the block was demonstrated at 48 kVA. The efficiency of the block was measured to be 98.2%.

Silicon carbide (SiC) devices have the advantage of high switching speed. However, the switching speed is limited by the high parasitic inductance which could cause high voltage overshoot, parasitic turn-on, oscillation and EMI issues. Thus, the parasitic inductance of the SiC power module has to be reduced for a better performance. This paper proposed an integrated half-bridge (HB) power module based on a DBC-stacked hybrid packaging structure. This packaging structure utilizes two direct bonding copper (DBC) substrate to stack together, which forms a three-dimensional (3D) power commutation loop. The SiC chips are embedded on the top of the bottom DBC substrate to reduce the thermal resistance. Based on an optimized mutual inductance cancellation design, the proposed DBC-stacked hybrid packaging structure has only 1.8 nH commutation power loop inductance for a 1200 V, 120 A half-bridge power module. Moreover, the geometrical parameters of the laminated power terminal have been analyzed and optimized for symmetrical current sharing in the multi-chip paralleled power module. A compact 1200 V, 120 A full SiC HB power module with integrated decoupling capacitors has been fabricated, and the DC-link capacitor board, gate drivers can be integrated on the power module compactly. Finally, the static and dynamic characteristics of the proposed module have been tested. The results of double pulse test under zero external driver resistor indicate that the voltage overshoot of the proposed module is reduced by approximately 55% compared to the commercial power module, and the total switching energy is only 43% of the commercial module. Moreover, the loss of the 5.5 kW single-phase inverter based on the proposed module is reduced by 28.3% compared with the inverter based on the commercial module under 120 kHz switching frequency.

Compared with traditional frequency limitation method DCM and QCFTCM for TCM-based inverter, this paper proposes a hybrid TCM method which can achieve both full range ZVS and frequency variation limitation. An accurate resonant transition model is established and the switching frequency variation range can be obtained for TCM. The hybrid control can be implemented according to the variation ratio y. In order to determine the optimal y, an offline optimization algorithm based on loss estimation is proposed. So, an accurate analytical loss model for GaN HEMTs considering the non-linear junction capacitance is given for TCM and hybrid TCM. The loss model shows that the total losses of hybrid TCM inverter is reduced compared with TCM. Moreover, an interleaved GaN-based MHz single phase inverter with digital control is demonstrated with 120 W/in3 power density. The aforementioned benefits are experimentally verified in the optimal hybrid TCM. With this hybrid control, the measured peak efficiency is 98%. Compared with pure TCM mode, there is a 70% reduction in the switching frequency and the related efficiency is 0.8% higher at light loads. Higher power density (135W/in3) can be achieved in hybrid TCM through further increasing the switching frequency compared with pure TCM.

Silicon carbide (SiC) devices have the advantages of high switching speed and high switching frequency, which can increase the power density, but electromagnetic interference (EMI) will increase along with higher switching frequency thus it can become a challenge for high frequency converters. In order to clarify the influence factors of EMI noise in SiC converters and find the suppressing method, this paper investigated the conducted EMI in SiC-based high power density electronic systems from two aspects: packaging structures and modulation methods. For packaging investigation, this paper introduced parasitic parameters of power module into EMI analytical model, then defined transfer functions of EMI noise to analyze the influence of parasitic parameters on noise propagation path, and further studied the impact of parasitic parameters on noise source by analyzing switching transient and frequency spectrum. Analysis and simulation are carried out based on a hybrid structure SiC power module and discrete SiC devices to verify the analysis. The influence of modulation on EMI is studied by analyzing and comparing two modulations: continuous current modulation (CCM), and triangle current modulation (TCM). To certify the analysis study, two 1.6kW, 300kHz switching-frequency synchronous buck converters are designed and tested. One is based on the hybrid packaging power module and the other is based on TO-247 packaged SiC devices respectively. The result shows that the hybrid packaging module can suppress the common mode (CM) EMI by 10dB, and has a suppression on differential mode (DM) EMI between 10MHz-20MHz. Moreover, TCM can increase DM EMI in low-frequency range but suppress it in the high-frequency range.