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    An active discharge scheme for DC-bus capacitors in EV powertrain
    (Institute of Electrical and Electronics Engineers Inc., 2025-07-18) Sezer, Mustafa Murat; Norwood, Daniel; Geiger, John; Hava, Ahmet Masum; Akın, Bilal
    During the emergency situations, key-OFFs, or maintenance, discharging the inverter dc-bus capacitor voltage within seconds is imperative due to safety concerns (inverter not used to control motor). Conventional discharge methods rely on external resistors, additional switches, or motor windings, increasing cost, space requirements, and control complexity. This article presents a cost-effective and space-efficient solution that enables fast capacitor discharge by operating the inverter's SiC mosfets-either discrete devices or power modules-in linear mode. The proposed method utilizes a constant power tracking approach with pulse frequency modulation to safely discharge the high-voltage bus capacitor without external components. When the car is off, the proposed scheme discharges a 1000-V dc bus within 1 s using a single low-side SiC switch to test a worst-case scenario. In practice, all six devices can be used to share thermal stress, and the discharge time can be extended to 5 s as suggested by safety standards. Optimal operating conditions, including gate-source voltage (V{GS}) and pulse width (t{ON}}), are identified for different mosfets from various vendors. To assess long-term reliability, devices undergo more than 200 000 discharge cycles, with intrinsic parameter monitoring and failure analysis conducted to determine degradation mechanisms. The findings help establish safe operating conditions, ensuring robust and reliable integration of the proposed discharge method within the main powertrain inverter.
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    Considerations for inverter topology selection and limitations in active power filtering applications
    (IEEE, 2022-03-31) Büyükdeğirmenci, Veysel T.; Sözüer, Abdurrahman; Milletsever, Özgür C.; Kozarva, Ömer F.; Öz, Taha; Hava, Ahmet Masum
    This paper presents a modular inverter structure utilizing hybrid SiC MOSFET based active neutral point clamped inverter for active power filter (APF) applications. An FPGA-based digital controller is developed. One major factor in APF applications is the harmonic current capability of the system at higher order harmonics. Commercial products often have a derating curve for higher order harmonic ratings. This paper presents a case utilizing SiC MOSFETs to increase the switching frequency and reduce the LCL filter size. The presented approach is shown to extend the harmonic current capability up to twice in comparison with conventional IGBT-based systems.
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    Design and control of high-frequency buck converter fed six-step drive for air-core PMSM
    (Institute of Electrical and Electronics Engineers Inc., 2025-02) Jena, Sritam; Kumar, Saurabh; Deshmukh, Akshay Vijayrao; Hava, Ahmet Masum; Akın, Bilal; Gabrys, Christopher; Rodgers, Timothy
    Air-core permanent magnet synchronous motors (PMSMs) machines are becoming known for their higher efficiency, lighter weight designs, and superior performance compared to widely utilized induction motors (IMs). They hold great potential for diverse industrial applications. However, effectively harnessing this potential requires overcoming drive hardware and control challenges. This research introduces a silicon carbide (SiC)-based two-phase interleaved buck-converter-fed quasi-current source inverter (quasi-CSI) drive tailored for driving low-inductance air-core PMSMs which is ideal for heavy-duty fan and pump applications. Operating in the discontinuous current mode (DCM) with an effective switching frequency of 1 MHz, this drive is designed to address efficiency and the very low-cost market constraints while simultaneously reducing control complexity an issue associated with its high switching frequency. The article also analyzes two critical control challenges of mitigating high current spikes due to air-core machines' low inductance and finding solutions to overcome microcontroller resource limitations when executing time-critical functions within interrupt subroutines (ISRs). The culmination of this work is a 300 V dc-bus and five-horsepower electric drive prototype with closed-loop speed control. Experimental results illustrate a 2% enhancement in overall efficiency compared to conventional induction machine (IM) drives in similar applications (e.g., fan and pump) and ratings, alongside a significant 50% reduction in drive volume.
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    Design trade-offs and considerations for improving the PCB current carrying capacity in high power density power electronics applications
    (IEEE, 2022-03-24) Büyükdeğirmenci, Veysel Tutku; Kozarva, Ömer F.; Milletsever, Özgür C.; Hava, Ahmet Masum
    This paper investigates printed circuit board (PCB) design trade-offs and considerations to maximize the current carrying capacity of traces in PCB-based power electronics applications. Many existing designs rely on methodologies through empirical data presented by the outdated IPC-2152 standard. A design methodology to maximize the utilized PCB area and improve thermal performance is introduced. To assess this methodology, lumped parameter (LP) and finite element (FE) models are developed and computational fluid dynamics (CFD) simulations are carried out. Thermal via placement strategies are investigated and maximum allowable power dissipation on the PCB traces is calculated. Simulations and analyses are experimentally validated on a PCB-based 100kW three-phase three-level inverter. The that results show that the thermal and electrical models discussed in this paper have superior accuracy compared to traditional formulations.
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    Inductor saturation compensation in three-phase three-wire voltage-source converters via inverse system dynamics
    (Institute of Electrical and Electronics Engineers Inc., 2022-05-01) Özkan, Ziya; Hava, Ahmet Masum
    In three-phase three-wire (3P3W) voltage-source converter (VSC) systems, utilization of filter inductors with deep saturation characteristics is often advantageous due to the improved size, cost, and efficiency. However, with the use of conventional synchronous frame current control methods, the inductor saturation results in significant dynamic performance loss and poor steady-state current waveform quality. This article proposes an inverse dynamic model-based compensation (IDMBC) method to overcome these performance issues. For this purpose, two-phase exact modeling of the 3P3W VSC control system is obtained. Based on the modeling, the inverse system dynamic model of the nonlinear system is obtained and employed such that the nonlinear plant is converted to a virtual linear inductor system for linear current regulators to perform satisfactorily. Further, to control phase currents in the synchronous frame, a two-phase coordinate transformation is proposed. The IDMBC method is tested via dynamic command response and waveform quality simulations and experiments that employ saturable inductors reaching down from full inductance at zero current to 1/9th inductance at full current. The results obtained demonstrate the suitability of the method for 3P3W VSCs employing saturable inductors.
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    A practical control method for single-phase input PMSM drives with small DC-Link capacitor
    (Institute of Electrical and Electronics Engineers Inc., 2025-03) Deshmukh, Akshay Vijayrao; Afshar, Mojtaba; Jena, Sritam; Hava, Ahmet Masum; Yu, Zhen; Akın, Bilal
    The primary function of the large electrolytic dc-link capacitor in the single-phase input motor drives is to enhance dc voltage stability by minimizing voltage fluctuations. Because they are both bulky and unreliable components, reducing the size of dc-link capacitors or substituting them with significantly low capacitance value film capacitors offers numerous advantages. This article introduces a method that allows using a voltage source inverter with a small film dc-link capacitor, which results in equivalent performance to high-value capacitor drives. In this approach, the effect of dc-link voltage ripple is designed as a periodic disturbance in the current loop. A proportional-integral-resonant (PIR) control strategy is implemented to eliminate the designed double-line frequency disturbance observed in motor currents, thereby ensuring a smooth motor torque response. This solution meets crucial criteria for home appliances, specifically addressing input current harmonic requirements through power factor correction while effectively reducing the adverse effects of substantial dc-link ripple on motor torque, even when employing a film capacitor (10–50 µF range). The proposed framework is experimentally tested on permanent magnet synchronous motors with fan-load and dynamometers. Experimental results demonstrate, with PIR, an 80% reduction in current and torque ripple occurring due to the use of a low-value dc-link film capacitor. This also achieves performance within ±5% of the results obtained with a drive equipped with a 1200 µF dc capacitor. In addition, the line-side power factor exceeds 0.98 for loads exceeding 8% of the rated power.