Hafsa Qamar

dblp:205/0973 · DBLP profile ↗
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6ranked-venue papers
2as first author
4since 2021 · last 2025
0000-0001-5381-4380ORCID · corroborated

Domains — the database's venue-derived domains; a paper can count in several

Systems, architecture and hardware · 4 · 1 first-author · 4 since 2021Artificial intelligence and machine learning · 2 · 1 first-author
YearPublicationVenuePosition
2025 Performance Evaluation and Experimental Validation of an Advanced PWM Method in SiC Based EV Charger
abstract
Electric vehicles (EVs) onboard charging systems require power converters that combine high efficiency with high power density. While higher switching frequencies can enhance power density, they also lead to increased switching losses, which challenge efficiency targets. Most onboard EV chargers adopt a front-end AC/DC converter followed by an isolated DC/DC stage that interfaces the EV battery with the AC grid. This paper proposes the novel application of the 240°-clamped space vector PWM (240CPWM) method in the AC/DC converter stage, enabling low switching losses even at higher switching frequency. A comprehensive power loss analysis is presented analytically along with simulation results at a 10 kW power level in both Grid-to-Vehicle (G2V) and Vehicle-to-Grid (V2G) modes. Furthermore, a 2 kW silicon carbide (SiC)-based hardware prototype of an EV onboard charger is developed to experimentally compare the performance of the proposed 240CPWM method against the conventional space vector PWM (CSVPWM). Experimental results at 2 kW in V2G mode indicate that the AC/DC converter employing 240CPWM achieves an efficiency of 98.2%, outperforming CSVPWM by 3.14% while maintaining similar total harmonic distortion (THD) in the line currents.
Syed Jahania Shah, Hafsa Qamar
IECON2
2025 Performance Evaluation of a Low-Loss PWM Method in Single-Stage Motor Drives
abstract
This paper presents a novel application of 240°-clamped space vector pulse width modulation (240CPWM) in a single-stage motor drive system operating with a constant DC link voltage. Unlike conventional implementations that require a dynamically varying six-pulse DC link voltage produced by a front-end DC-DC converter, the proposed approach eliminates the need for the intermediate stage, thereby simplifying the motor drive architecture, reducing the component count and the power losses. The effectiveness of the proposed 240CPWM scheme is experimentally evaluated using a motor load, with performance assessed in terms of inverter efficiency and current quality. A detailed comparison is conducted between three modulation strategies: (i) the proposed single-stage 240CPWM with a constant DC link, (ii) conventional two-stage 240CPWM with a dynamic DC link, and (iii) the widely used conventional space vector PWM (CSVPWM) in a single-stage setup. Experimental results with motor load at approximately 1 kVA show that the proposed method achieves a peak efficiency of 98.8%, outperforming both CSVPWM and two-stage 240CPWM implementations, which achieve up to 95% efficiency. This 3.8% improvement in inverter efficiency is achieved at the cost of moderate distortion in the line currents. These findings demonstrate the potential of 240CPWM with constant DC link for efficient and simplified single-stage motor drive applications.
Syed Jahania Shah, Hafsa Qamar
IECON2
2023 An Advanced PWM Method for Highly Efficient Power Train in Hybrid Electric Propulsion Aircrafts
abstract
This paper presents the application of a low-loss PWM method called 240° clamped space vector PWM (240CPWM) in hybrid electric propulsion (HEP) aircrafts. 240CPWM allows 85% reduction in switching loss at unity power factor which improves the inverter efficiency significantly as compared to conventional space vector PWM (CSVPWM). 240CPWM requires a unique six-pulse dynamically varying DC link voltage which is regulated by a close loop control in DC-DC converter. In HEP aircrafts, DC-DC converter is often implemented between battery packs and inverter to regulate the charging and discharging of the battery which allows the use of 240CPWM without adding any components or changing the powertrain architecture. Besides higher voltages and power in HEP aircrafts as compared to hybrid electric vehicles, the fundamental frequency is also very high which makes the control of dynamic DC link voltage challenging. PLECS simulation results of a HEP aircraft at 250 kW and fundamental frequency of 300 Hz are shown with power efficiency of 98.7% for DC-AC stage with 240CPWM. Experimental result at 5 kW and fundamental frequency of 300 Hz shows a precise control of six-pulse dynamic DC link voltage. The inverter efficiency from experimental prototype for 240CPWM is 98.5% whereas it reduces to 97% for CSVPWM. Hence, 240CPWM is a viable PWM method for HEP aircrafts that results in substantial savings in power losses in the DC-AC stage as compared to CSVPWM.
Hafsa Qamar, Haleema Qamar
IECON1
2021 Performance Evaluation of Space Vector PWM Methods with DC Link Voltage Control for EV/HEV Powertrains
abstract
Performance evaluation and experimental validation of space vector PWM techniques with DC link voltage control in cascaded architecture of DC-DC stage followed by DC-AC stage for EV/HEV powertrain is carried out. 240°-Clamped PWM (240CPWM) and Advanced Bus Clamped PWM (ABCPWM) are the best performing PWM methods considering the combined performance of THD in line currents and efficiency. 240CPWM and ABCPWM are studied in detail both with constant and variable DC link voltage control and compared with benchmark PWM methods i.e., CSVPWM and DPWM1. Cascaded topology operation of DC-DC stage with DC-AC stage that allows the variable DC link voltage control in EV/HEV powertrain is studied in detail. Experimental results from a 10 kW hardware prototype are presented. Supremacy of one PWM method over the other is based on combined best performance in terms of THD and efficiency. 240CPWM outperforms all other PWM methods under consideration which is shown by a performance metric developed on the basis of combined performance of THD and efficiency.
Haleema Qamar, Hafsa Qamar, Raja Ayyanar 0001
IECON2
2019 Local, global and decentralized fuzzy-based computing paradigms for coordinated voltage control of grid-connected photovoltaic systems
Alfredo Vaccaro, Hafsa Qamar, Haleema Qamar
Soft Comput.2
2017 Design of fuzzy logic controllers for decentralized voltage regulation in grid connected photovoltaic systems
abstract
This paper outlines the potential role of Fuzzy Logic Control (FLC) for voltage-rise mitigation in power distribution networks in the presence of grid-connected photovoltaic (PV) systems. In particular, after analyzing the main performances of the traditional techniques currently adopted for voltage rise mitigation by reactive power compensation, a decentralized approach based on local fuzzy controllers is proposed to regulate the reactive power injected into the grid by the distributed PV systems. The proposed solution is based on a closed control loop, where the local voltage at the point of common coupling (PCC) is fed at input to the FLC to decide the amount of reactive power generated by the local PV systems. The results obtained on a realistic case study are presented and discussed in order to assess the benefits deriving by the application of the proposed approach.
Hafsa Qamar, Haleema Qamar, Alfredo Vaccaro
FUZZ-IEEE1