Assel Sakanova

Design of high power density converter for aircraft applications

This paper presents a design methodology for high power density converter (HPDC) operating as an AC aircraft bus provider, which presents a particular gravimetric power density challenge. High power rating 3-phase AC-DC converter design with weight minimization is elaborated. By considering sizing of major converter parts that contribute to total converter weight, optimal switching frequency to yield highest power density is evaluated. The design evaluation for 50 kW converter with SiC power modules yields overall gravimetric power density of 3.76-5.35 kW/kg at optimal switching frequency of 60 kHz and volumetric power density of 7.04-7.38 kW/l respectively.

Gate driver optimization to mitigate shoot-through in high-speed switching SiC half bridge module

The high-speed switching of SiC MOSFET allows power converter to operate with higher frequency and lower switching loss. However, it tends to aggravate dv/dt effect due to the impact of parasitic parameters, resulting in shoot-through and high device stress in the half bridge configuration. In this study, a compact and high-speed gate driver is developed and optimized for SiC half bridge module. The impact of various circuit parameters including Miller capacitance, common source inductance, gate resistance and gate inductance is evaluated. The improved gate drivers with additional features are compared and optimized to eliminate shoot-through.

Investigation on the Influence of Nanofluids in Wavy Microchannel Heat Sink

This paper for the first time numerically investigates improvement of the heat transfer using wavy walls in microchannel heat sink (MCHS) with nanofluids as coolant. The effects of wavy amplitude, wavelength, volumetric flow rate, and volume fraction of different types of nanofluids are studied. Commonly used nanofluids like diamond-water, SiO2-water, and CuO-water nanofluids with temperature-dependent properties and nanoparticle volume fractions ranging from 1% to 5% are adopted. The results verify that the wavy MCHS yields better cooling performance than the traditional rectangular MCHS with pure water and nanofluids as coolants. Higher amplitude and shorter wavelength provides lower thermal resistance. However, the influence of nanofluids in wavy channel deteriorates with the increment in the amplitude and the decrement in the wavelength. Also with nanofluids at a high volume concentration of 5%, there is no significant difference in the performance observed between the wavy MCHS and the rectangular MCHS. The combination of wavy channel with a high volume concentration of nanofluids does not show the superior performance over the traditional channel with the same nanofluids and volume concentration.

Evaluation on filter topologies in high power density converter design for power quality and EMI control

This paper evaluates different passive filter topologies of the grid-connected high power density converter (HPDC) for the purpose power quality control and electromagnetic interference (EMI) reduction. The harmonics generated by the switching circuits in the HPDC affect power quality at lower frequency as well as EMI at higher frequency. Various common passive filter topologies are carefully evaluated in terms of reduction of total harmonic distortion (THD) and EMI.

Heatsink design for high power density converter in aircraft applications: Parameter sensitivity analysis

Cooling systems significantly contribute to the total mass and/or volume of power electronic systems especially for aerospace application where it will directly increase the operating cost of the aircraft. This paper investigates the heat sink parameters that contribute to the thermal resistance as well to weight of the high power density converter. The lowest heat sink thermal resistance for any type of coolant can be achieved by choosing a greater number of flow channels and thicker fin thickness. To minimize the weight, lower number of channels and thinner fins are desirable. The design case of 50kW power converter with 1.16% power loss using the most promising coolant in aircraft application is investigated and presented. Manufacturing constrains of the heat sink have also been taken into account.

Challenges in switching waveforms measurement for a high-speed switching module

As SiC MOSFET is moving towards high current rating through parallel devices in a module, the ability to switch it fast with minimum switching loss becomes a new challenge. Amid this new challenge, power converter designers need to deal with more demanding measurement method to obtain correct switching waveforms. Switching waveforms are an important asset for converter designers because they can reveal vital parasitic information, indicate any potential overshoot or undershoot and estimate the switching loss. This paper shares the experimental work results, its measurement techniques (current and voltage) and test setup use to obtain minimum voltage overshoot of a 5 parallel SiC devices module. The cable length (of voltage probe) is shown to directly affect the switching loss estimation especially when a fast 5Ω gate driver resistance is used.

FEM modelling of three-phase common mode choke for performance evaluation

This paper presents the extraction of common mode (CM) and differential mode (DM) inductances of a common mode choke (CMC) using 3D finite element method (FEM). For optimal performance of the CMC, the effects of CM and DM currents on the magnetic core saturation are investigated. As the parasitic capacitance of a CMC is a critical parameter that affects its high frequency performance, the parasitic capacitances of the turn-to-turn and the turn-to-core capacitances of different winding layouts are also extracted for comparison. Finally, different core structures are modeled and simulated for performance evaluation.

Analysis and design of coupled inductor and output harmonic filter for interleaved three phase VSCs

This paper presents the benefits of interleaving three phase voltage source converters (VSCs) to improve the power density. The output harmonics are also analyzed in frequency domain, then design and optimization of coupled inductor and output filter are given. Verifications are carried out through electrical circiut and electromagnetics FEM simualtions. Finally, the inductor weight are compared with and without interleaving.

Weight consideration of liquid metal cooling technology for power electronics converter in future aircraft

Cooling system becomes a serious concern due to weight and volume contribution of power electronics system in aerospace sector. This research investigates the contribution of cooling system to the total weight of power electronics converter when liquid metal cooling is applied. In addition, it is compared with the traditional working fluid (water). It is concluded that cooling system could be much lighter if the liquid metal cooling is introduced. In this study the introduction of liquid metal cooling results in 12 times lighter pump.

Comparative investigation of double-layer and double-side micro-channel cooling for power electronics packaging

In present work, micro-channel heat sink (MCHS) is integrated inside direct bond copper (DBC) for power electronics cooling. Based on commercial CFD code ANSYS Fluent, micro-channels are designed in back Cu-layer of DBC substrate with liquid water as coolant. Two advanced cooling structures, including double-layer (DL) and double-side (sandwich) micro-channel, are investigated. The sandwich structure with counter flows shows reduction in thermal resistance by 59%, 52% and 53% when compare with single-layer (SL), DL with unidirectional flows and DL with counter flows respectively. It also promises uniform temperature-distribution.