Power Electronics

A Single-phase Delta-conversion UPS With Reduced Components

by Alireza Fatemi

3rd Power Electronics and Drive Systems Technology Conf

A recently introduced reduced switch count converter family uses three switches in the legs of its single-phase,... more A recently introduced reduced switch count converter family uses three switches in the legs of its single-phase, threephase and four-leg converters. So far, the benefits and drawbacks of such converters have been widely investigated in the literature in several applications. This paper studies and proposes the single-phase six-switch converter to be implemented in deltaconversion uninterruptible power supply system. In this
application the intrinsic limitations of the three-switch leg structure such as diminished dc bus voltage utilization is overcome and the attractive features of the conventional system are retained yet less number of power switches are employed. The proposed UPS enjoys integrated structure, effective performance and optimized utilization of device ratings at both series and parallel sides. The proposed configuration is presented and its control scheme and new hysteresis modulation are elaborated. The system operation is verified through simulation.

Cost-effective Solution for Microgrid Power Quality Assurance Using Dual-output Four-leg Converter

by Alireza Fatemi

in 3rd Power Electronics and Drive Systems Technology Conf

In this paper, an optimum interface configuration is proposed which can be used for connecting a microsource to a weak... more In this paper, an optimum interface configuration is proposed which can be used for connecting a microsource to a weak utility. The proposed configuration simultaneously conditions the quality of the power delivered to the supplied loads in the microgrid. This system employs a recently introduced reduced switch count dual-output inverter in a mode of operation named Equal Frequency which offers the best operation features such as maximum dc bus voltage utilization and minimum device ratings. Compared to the counterpart system, the proposed configuration enjoys an integrated structure and less number of semiconductor switches while possessing the same principal characteristics such as ability to compensate unbalanced and distorted utility or the ability to supply three-phase unbalanced loads with balanced and ceaseless voltage. The proposed system is developed, its carrier based modulation scheme is elaborated and a simple control strategy is devised for it. The validity of operation of the proposed system is verified through simulation.

Theoretical Design of Compact Multi-phase Interleaved Buck DC-DC Converter for Automotive Power Applications

by Paolo Emilio Bagnoli

co-authored with Yabin Zhang and Emilio Franchi, to be presented at SPEEDAM 2012 Conference, Sorrento Italy

Theoretical design of a multiphase interleaved buck DC-DC converter is introduced based on corresponding requirements... more Theoretical design of a multiphase interleaved buck DC-DC converter is introduced based on corresponding requirements from automotive industry. Particularly, multiphase interleaved topology is adopted to prevent much heat generated in devices and large voltage ripple in the load. Ceramic capacitors will be used to replace electrolytic capacitors in order to meet the requirement of long life-time. Control strategy in the converter is mainly based on formulas derived for calculating duty cycle of PWM signals in both continuous mode and discontinuous mode. PID control is also included to correct the error generated from the difference in duty cycle between the ideal condition and the actual one as well as to realize fast recovery of nominal output during variation of working condition, such as variation of input voltage and variation of load. All control functions will be realized by means of a single microcontroller. The theoretical design has been tested through simulation in Simulink model, in which particular sampling frequency and control frequency of the actual microcontroller were taken into account.

A Minimized Switch Count Single-phase AC/AC Converter with Active Front End

by Alireza Fatemi

in 27th Annual IEEE Applied Power Electronics Conference and Exposition (APEC)

A three-switch single-phase converter is introduced in this paper which is a counterpart to back-to-back half-bridge... more A three-switch single-phase converter is introduced in this paper which is a counterpart to back-to-back half-bridge converters. Introducing the new converter and elaborating its modulation scheme, a single-phase ac/ac converter is proposed based on it. The proposed topology enjoys the benefits of an ideal single-phase ac/ac converter such as low THD input current, unity power factor, fast dynamic response and the ability to compensate input voltage sag/surge when supplying linear or nonlinear loads. The operation of the proposed system is validated through simulation.

Single-phase Dual-output Inverters with Three-switch Legs

by Alireza Fatemi

in IEEE Transactions on Industrial Electronics (TIE)

In this paper, two reduced switch count topologies are introduced for independently supplying two single-phase ac... more In this paper, two reduced switch count topologies are introduced for independently supplying two single-phase ac loads with one inverter. Using a new three-switch leg structure recently introduced and implemented in three-phase converters, two types of dual-leg and single-leg topologies are developed which respectively are functionally comparable to two full-bridge and half-bridge inverters working independently though with a less number of semiconductor switches and hence control and gate drive circuit components. The proposed six-switch and three-switch topologies are introduced; two modes of equal frequency (EF) and different frequency (DF) operation each of its own distinctive characteristics are considered for them and their PWM schemes are elaborated. Comprehensive analyses of power loss profile and output waveform properties are conducted via simulation for the proposed inverters and the results are compared with full bridge and half bridge inverters. To assess the performance of the proposed inverter topologies, working prototypes are built and the experimental results are provided.

A Wide Input-Output Voltage Range AC-DC Converter with a Fuzzy PI+D Controller

by Farhad Ghadaki

"Co-authored with Mohammad Bagher Akbari Haghighat", "Co-authored with Mohammad-Ali Shamsi-Nejad"

This paper presents a two stage wide input-output voltage range ac-dc converter. First stage of the converter is a... more This paper presents a two stage wide input-output voltage range ac-dc converter. First stage of the converter is a commercially available front-end boost power factor corrector (PFC) and second stage is a simple step-down dc-dc converter. This work is based on classical off-line ac-dc power supplies architecture. The main improvement is the employment of Fuzzy Proportional-Integral-Derivative (FPI+D) controller to control the step-down converter. The main goal of the utilized controller is to regulate the output voltage in a wide range of reference voltage and load changes. Achieving these goals is possible by applying this robust controller that can handle inherent nonlinearities of dc-dc converters operating in both continuous-conduction-mode (CCM) and discontinuous-conduction-mode (DCM). Besides simulation results, a 200W universal-line hardware prototype was built to evaluate the proposed scheme experimentally. Developed prototype has the input voltage range of 85-265 Vac and the wide output voltage range between 10-200 Vdc.

Direct control based on sliding mode techniques for multicell serial chopper

by Leonardo Amet

Measurement-based load modelling for power supply system design

by Valeria Boscaino

Non-linear digital control improving transient response: Design and test on a multiphase VRM

by Valeria Boscaino

A lossles current sensing technique for flyback converters

by Valeria Boscaino

An innovative PWM loop control for VRMs

by Valeria Boscaino

An improved Flyback converter

by Valeria Boscaino

A demagnetization circuit for forward converters

by Valeria Boscaino

Image processing to automate condition assessment of overhead line components

by Wai Ho Li

A Novel Reduced Switch Count Single-Phase to Three-Phase AC/AC Converter

by Alireza Fatemi

37th Annual Conference of the IEEE Industrial Electronics Society (IECON), 7-10 Nov., 2011

Recently, reduced-switch-count converters have garnered particular attention in power electronic systems due to the... more Recently, reduced-switch-count converters have garnered particular attention in power electronic systems due to the numerous advantages such as low cost, low weight and volume, and high reliability offered by them. In this paper, a new reduced-switch-count converter topology is proposed as a single-phase to three-phase ac/ac converter. This converter employs less number of semiconductor devices compared to former single-phase to three-phase ac/ac converters. The modulation scheme of the novel converter is developed and two methods are devised for enhancing DC bus voltage utilization and hence minimizing the output voltage THD and the switching loss. The proposed converter features sinusoidal input and output, unity input power factor, and more importantly, low manufacturing cost. The validity of theoretical issues is confirmed by simulation results.

A Novel Dual-Output Six-Switch Three-Phase Inverter

by Alireza Fatemi

37th Annual Conference of the IEEE Industrial Electronics Society (IECON), 7-10 Nov., 2011

A novel dual-output six-switch inverter topology is proposed in this paper for independently supplying two three-phase... more A novel dual-output six-switch inverter topology is proposed in this paper for independently supplying two three-phase loads. This inverter employs less number of semiconductor devices compared to former dual-output inverters proposed so far in the literature. Reducing the number of switches and hence drive and control circuits results in reduction in total cost and loss and increases the system efficiency and reliability. The new configuration is introduced and carrier-based PWM schemes for its two defined modes of operation (constant frequency and variable frequency modes) are developed. Furthermore, analysis of semiconductor loss is performed and the results are compared with counterpart topologies. Simulation and experimental results will be presented to confirm the theoretical basis.

Intellectual Property Law

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Intellectual Property Law

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A Wide Input-Output Voltage Range AC-DC Converter with a Fuzzy PI+D Controller

by Mohammad Bagher Akbari Haghighat

International Review of Automatic Control (IREACO), Praise Worthy Prize, vol. 4, no. 5, pp. 678-687, September 2011.

This paper presents a two stage wide input-output voltage range ac-dc converter. First stage of the converter is a... more This paper presents a two stage wide input-output voltage range ac-dc converter. First stage of the converter is a commercially available front-end boost power factor corrector (PFC) and second stage is a simple step-down dc-dc converter. This work is based on classical off-line ac-dc power supplies architecture. The main improvement is the employment of Fuzzy Proportional-Integral-Derivative (FPI+D) controller to control the step-down converter. The main goal of the utilized controller is to regulate the output voltage in a wide range of reference voltage and load changes. Achieving these goals is possible by applying this robust controller that can handle inherent nonlinearities of dc-dc converters operating in both continuous-conduction-mode (CCM) and discontinuous-conduction-mode (DCM). Besides simulation results, a 200W universal-line hardware prototype was built to evaluate the proposed scheme experimentally. Developed prototype has the input voltage range of 85-265 Vac and the wide output voltage range between 10-200 Vdc.

Keywords: Fuzzy PI+D Controller, Pulse-Width-Modulated (PWM) Converter, Switched-Mode Power Supplies (SMPS), Universal-Line AC-DC Converter.

AC series voltage regulator for permanent magnet generators

by Paolo Emilio Bagnoli

Application of Dual-output Four-leg Converter for Unified Power Quality Conditioner

by Alireza Fatemi

19th Iranian Conference on Electrical Engineering, May 2011

This paper proposes a novel UPQC system based on dual-output four-leg converter. The proposed system completely... more This paper proposes a novel UPQC system based on dual-output four-leg converter. The proposed system completely fulfils the main functions of the conventional UPQC system. It is also capable of compensating any unbalance characteristics at load side (parallel side) or grid side (series side) such that the drawn currents from the grid and the voltage of the load are balanced and sinusoidal, regardless of the load or utility voltage characteristics. Another advantage of the proposed system is that despite the conventional type in which series convertor is underutilized due to its low modulation index, the proposed system is fully utilized at both series and parallel sides. Moreover, the number of semiconductor devices is reduced compared to counterpart topologies. The validity of operation of the proposed UPQC is verified via simulation.