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Application of random PWM technique for reducing the conducted electromagnetic emissions in active filters
, Article IEEE Transactions on Industrial Electronics ; Volume 54, Issue 4 , 2007 , Pages 2333-2343 ; 02780046 (ISSN) ; Mahdavi, J ; Agah, A ; Sharif University of Technology
2007
Abstract
A pulsewidth modulation (PWM)-controlled active filter generates harmonics at the switching frequency and its multiples in the RF range, and the concentrated power spectrum may produce electromagnetic interference (EMI) problems. In this paper, the random PWM (RPWM) technique is applied in order to spread the noise spectrum over a wide range, thus, considerably reducing the amplitudes of these harmonics and the consequent EMI problems. To study the operation of active filters, the case of an ac/dc converter along with a power-factor corrector is considered as a nonlinear load and a series active filter, respectively. A line impedance stabilization network is used to study the RF noise...
Operation and design analysis of an interleaved high step-up DC–DC converter with improved harnessing of magnetic energy
, Article International Journal of Circuit Theory and Applications ; Volume 49, Issue 2 , 2021 , Pages 221-243 ; 00989886 (ISSN) ; Tarzamni, H ; Kolahian, P ; Sharif University of Technology
John Wiley and Sons Ltd
2021
Abstract
In this paper, a new interleaved DC–DC converter based on a coupled and a single input inductor is proposed. The suggested high step-up converter utilizes various inductive and capacitive methods to transfer magnetic energy more efficiently. The output voltage is regulated with the switches' duty cycle and the coupled inductor (CI) turns ratio, which provide a wide output voltage range. Interleaving improves the converter reliability, employs both the first and third areas of CI's B-H plane, cancels DC component of the CI, and reduces the input current ripple of the proposed converter with twice switching frequency. Utilization of two output ports for voltage stress and ripple reduction in...
A 3.3 V/1 W class D audio power amplifier with 103 dB DR and 90% efficiency
, Article 2002 23rd International Conference on Microelectronics, MIEL 2002, Nis, 12 May 2002 through 15 May 2002 ; Volume 2 , 2002 , Pages 581-584 ; 0780372352 (ISBN); 9780780372351 (ISBN) ; Sahandi, F ; Atarodi, M ; Shojaei, M ; Sharif University of Technology
IEEE Computer Society
2002
Abstract
A single-chip Integrated circuit of 3.3 V/1 W class-D high fidelity and high efficiency audio power amplifier is presented in this paper. The design has been done using a 3.3 V/0.25 /spl mu/m CMOS process. The maximum output power is 1 W before the amplifier saturates. The THD+N at 0.5 W output power is below 0.03% and efficiency is better than 90% thanks to the careful design of the output stage. The dynamic range is more than 100 dB suitable for high fidelity audio applications. A single-loop single-bit third order sigma-delta modulator is used to generate the PWM signal from input audio signal. The PWM signal is then filtered at the output with a second order low pass filter external to...
Optimization of Dynamic Wireless Power Transfer for Maximum Power Transmission to Electric Vehicles
, M.Sc. Thesis Sharif University of Technology ; Tahami, Farzad (Supervisor)
Abstract
Nowadays, due to environmental problems, electric cars are becoming more and more popular. The main drawback of these cars is due to the large volume, weight, and price of the battery and its long charging time. Charging the battery at short intervals or even in moving, can help to use a smaller battery and reduce battery problems. Therefore, the dynamic wireless power transmission technology that provides power without having to stop the car to recharge its batteries can revolutionize the electric car industry. The ever-expanding advance of power electronics and wireless power transmission technologies has made it possible to transfer power to moving electric cars. Barriers to this industry...
Improving the Direct Switching Method for High Voltage Applications to Improve the Load Voltage Waveform
, Ph.D. Dissertation Sharif University of Technology ; Kaboli, Shahriyar (Supervisor)
Abstract
Pulsed power supplies are used in linear accelerators, pulsed lasers, nuclear welding, radar, some medical applications, etc. which require much more instantaneous power than average power. These sources store energy in an energy storage element for a relatively long period of time and then release this energy in a short period of time. Among the most important goals pursued in these power supplies are the quality of the output pulse, the reliability and lifetime, efficiency, and cost, which depending on their application, some of these features are more important. One of the important applications of pulsed wave power supplies is their use to power microwave lamps. In some applications of...
Optimizing the normalized dead-time and maximum switching frequency of a wide-adjustable-range LLC resonant converter
, Article IEEE Transactions on Power Electronics ; Volume 26, Issue 2 , August , 2011 , Pages 462-472 ; 08858993 (ISSN) ; Rashidian, B ; Zolghadri, M. R ; Alavi, S. M. H ; Sharif University of Technology
2011
Abstract
LLC resonant converter has been widely used in dcdc converters. In this paper, optimum dead-time and maximum switching frequency of a wide-adjustable-range LLC resonant converter are investigated for realizing the zero voltage switching (ZVS) operation even under the worst-case conditions. Analyses demonstrate that these parameters depend on the converter inductance ratio and ratio of the converter resonant capacitor and the effective capacitance appeared in parallel with the drainsources of the power MOSFETs. The necessary dead time for realizing the ZVS operation can be minimized by choosing the normalized maximum switching frequency, properly. Using the dead-time optimum value, soft...
Using LLC resonant converter for designing wide-range voltage source
, Article IEEE Transactions on Industrial Electronics ; Volume 58, Issue 5 , 2011 , Pages 1746-1756 ; 02780046 (ISSN) ; Rashidian, B ; Zolghadri, M. R ; Alavi, S. M. H ; Sharif University of Technology
Abstract
LLC resonant converter with significant resonant inductance is proposed for designing an adjustable wide-range regulated voltage source. Large resonant inductance increases output voltage adjustment range and conversion efficiency, particularly at light loads. Soft switching is achieved for all power devices under all operating conditions by choosing the dead time and maximum switching frequency properly and operating in the converter's inductive region. Using a power-factor-correction (PFC) converter reduces the resonant converter's output voltage dependence to the variations of the main ac input voltage. Thus, the compensation of the load variations and the wide-range adjustment of the...
A new modeling and control scheme for cascaded split-source converter cells
, Article IEEE Transactions on Industrial Electronics ; 2021 ; 02780046 (ISSN) ; Milimonfared, J ; Zolghadri, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Cascaded split-source inverter (CSSI) is a new single-stage modular multilevel topology. Each cell of this converter converts DC to AC power in the buck or boost operation mode without any additional power switch. This paper develops a design method based on a detailed model for CSSI. This model shows that energy storage elements experience double-fundamental frequency ripples besides high-frequency ones. It accurately calculates voltage gains and capacitor voltage and inductor current ripples. On the other hand, common carrier-based multilevel modulations have been modified in terms of both reference and carrier signals to control the inverter under symmetric and asymmetric conditions. With...
Small-signal modeling and fast response control strategy for DCVM Cúk converters in PFC applications.انجام شد
, Article Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC ; 2011 , Pages 1795-1802 ; 9781424480845 (ISBN) ; Karimi, Y ; Zolghadri, M. R ; Ahmadian, M ; Moayedi, A ; Davoudi, A ; Sharif University of Technology
Abstract
Cúk Converter operating in discontinuous capacitor voltage mode is an inherent PFC converter in which, unity power factor can be achieved using constant duty cycle and switching frequency. In this paper, a reduced-order switch network modeling technique is applied to Cúk converter operating in DCVM in order to derive small-signal model of the converter assuming a dc voltage source as the input source of the converter. This model is extended to derive the small-signal behavior of the converter while operating as a PFC converter. The validity of the proposed model is confirmed by both simulation and experimental results. Afterwards, a new control strategy is proposed in which switching...
Improve the Direct Torque Control Method for Brushless Doubly Fed Induction Machines
, M.Sc. Thesis Sharif University of Technology ; Oraee Mirzamani, Hashem (Supervisor) ; Barati, Farhad (Co-Advisor)
Abstract
The Brushless Doubly Fed Induction Machine (BDFIM) has the potential to be used as a generator or motor in adjustable speed variables. But the most important application for the BDFM is to work as a wind generator. Due to this ability it can be considered as a rival for the Doubly Fed Induction Generator (DFIG) that is the most common type of the wind power generators nowadays. Because of problems of relater to brushes in DFIG, the BDFM has more resisted structure compared to the DFIG. Thanks to the special “nested loop” structure of rotor and two different coils on the stator without direct coupling between them, three different operation modes are possible for the BDFM.The synchronous...
Design of DC-DC Buck Converter Based on Reliability Considerations
, M.Sc. Thesis Sharif University of Technology ; Kaboli, Shahriyar (Supervisor)
Abstract
Nowadays power electronic devices have a wide usage in the industries for power conditioning. As a point of view, reliability is one of the most important figure of merits that should be considered to have long life time and also have more probability to do exactly the proposed mission. One of the widely used converter topologies is DC-DC step down converter which is used in different applications such as battery charger and voltage regulator. In this project, a step down DC-DC converter with Buck topology is designed with reliability consideration. Failure rate of power components are predicted based on MIL-HDBK-217. In addition, failure rate of auxiliary components of power devices are...
Frequency limitation due to switching transition of the bias current in bidirectional RSFQ logic
, Article Journal of Superconductivity and Novel Magnetism ; Volume 30, Issue 12 , 2017 , Pages 3619-3624 ; 15571939 (ISSN) ; Zandi, H ; Fardmanesh, M ; Sharif University of Technology
Abstract
Switching time limitations of the ac bias current of Josephson junctions in bidirectional rapid single flux quantum (RSFQ) logic circuits are investigated in order to determine the limits to the maximum possible operating frequency. We introduce a new approach based on modifying the bias current parameters and determining the inductance values in the circuit for reducing the switching transition time of the bias current through the junctions. We have simulated and optimized the timing and the operation of the bidirectional nondestructive readout and Josephson transmission line cells in this respect to demonstrate the results of utilizing the proposed approach. We successfully reduced the...
A variable switching frequency control method for active front end multilevel rectifier
, Article 17th IEEE International Conference on Environment and Electrical Engineering and 2017 1st IEEE Industrial and Commercial Power Systems Europe, EEEIC / I and CPS Europe 2017, 6 June 2017 through 9 June 2017 ; 2017 ; 9781538639160 (ISBN) ; Khodabandeh, M ; Zolghadri, M. R ; Rodriguez, J ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Conventional back-to-back converters with input power factor correction are still the best solution for motor drive applications which are usually subjected to considerable load changes during their operation. Since converter components, especially input-side inductances are designed for nominal power rating, the rated input power factor and input current distortion aren't achievable in light loads. In this paper a control method is proposed to improve the input current distortion and input power factor in light loads. This is achieved by increasing the switching frequency according to the reduction in load. Since conduction and switching losses decrease in light loads, the overall losses by...
A robust maximum power point tracker with fully analog implementation
, Article 8th Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2017, 14 February 2017 through 16 February 2017 ; 2017 , Pages 490-495 ; 9781509057665 (ISBN) ; Rajaei, A. H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
An analog circuit for maximum power point tracking of a PV battery charger with minimum number of elements is proposed which works in a full range condition with a fixed switching frequency. In conventional MPPT algorithms which provide PV current or voltage reference value as output, fast climate changes may cause system instability. Here, a new variable is defined to eliminate the problem and improve the stability of the system. In order to compare the presented circuit with a conventional system, perturb and observe (P&O) MPPT algorithm which is well-known in PV systems is implemented on the same system. Simulation results (Conventional P&O algorithm and proposed structure) are presented...
A new variable frequency zero voltage switching control method for boost converter operating in boundary conduction mode
, Article International Journal of Engineering, Transactions B: Applications ; Volume 33, Issue 11 , 2020 , Pages 2222-2232 ; Ghoreishy, H ; Ale Ahmad, A ; Tahami, F ; Sharif University of Technology
Materials and Energy Research Center
2020
Abstract
This paper proposes a new variable frequency zero voltage switching (ZVS) control method for boost converter operating in boundary conduction mode (BCM). The intended method keeps the converter in BCM despide of the load and input voltage variations. This is done by changing switching frequency in a certain specified range. The proposed method can guarantee circuit performance in BCM via zero-crossing detection of the inductor current and changing the switching frequency. In addition, with a slight modification in control structure, it is possible to achieve a fully ZVS in all cases. This converter control is carried out in analog form without using microprocessors which, compared with the...
Comprehensive analytics for reliability evaluation of conventional isolated multiswitch PWM DC-DC converters
, Article IEEE Transactions on Power Electronics ; Volume 35, Issue 5 , 2020 , Pages 5254-5266 ; Panahandeh Esmaeelnia, F ; Fotuhi Firuzabad, M ; Tahami, F ; Tohidi, S ; Dehghanian, P ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
This article offers a holistic model and approach on reliability assessment of conventional isolated multiswitch pulsewidth modulation dc-dc (IMSDC-DC) power electronic converters with conventional half-bridge, full-bridge, and push-pull dc-dc topologies. The proposed reliability assessment analytics encapsulate correlated effects of several conditions (e.g., open- and short-circuit faults) and prevailing parameters (e.g., duty cycle, input voltage, output power, transformer turns ratio, voltage gain, switching frequency, operation time duration, and components characteristics) on the overall reliability performance of IMSDC-DC converters. Such insights are then harnessed within a Markov...
Structural and magnetic evaluations of rare-earths (Tb, Pr, Ce, Gd, Y)-doped spinel ferrites for high frequency and switching applications
, Article Journal of Materials Science: Materials in Electronics ; Volume 32, Issue 6 , 2021 , Pages 7692-7703 ; 09574522 (ISSN) ; Akhtar, M. N ; Baqir, M. A ; Ahmad, A ; Khallidoon, M. U ; Farhan, M ; Khan, M. A ; Sharif University of Technology
Springer
2021
Abstract
NiZn nanoferrites doped with rare-earth cations having stoichiometric composition such as Ni0.5Zn0.5R0.02Fe1.98O4 (R = Tb, Pr, Ce, Gd, Y) were prepared by sol–gel technique. The same amount of Ni and Zn with constant ratio of different rare-earths ions were doped to investigate the variations in the properties. X-ray diffraction (XRD), Field emission electron microscope (FESEM), and vibrating sample magnetometer (VSM) were used to investigate the structure, morphology, and magnetic properties of rare-earth doped NiZn nanoferrites, respectively. X-ray density, bulk density, and porosity were also calculated. Phase, crystallite size, structure, d-spacing, lattice parameter, micro strain, and...
Structural and magnetic evaluations of rare-earths (Tb, Pr, Ce, Gd, Y)-doped spinel ferrites for high frequency and switching applications
, Article Journal of Materials Science: Materials in Electronics ; Volume 32, Issue 6 , 2021 , Pages 7692-7703 ; 09574522 (ISSN) ; Akhtar, M. N ; Baqir, M. A ; Ahmad, A ; Khallidoon, M. U ; Farhan, M ; Khan, M. A ; Sharif University of Technology
Springer
2021
Abstract
NiZn nanoferrites doped with rare-earth cations having stoichiometric composition such as Ni0.5Zn0.5R0.02Fe1.98O4 (R = Tb, Pr, Ce, Gd, Y) were prepared by sol–gel technique. The same amount of Ni and Zn with constant ratio of different rare-earths ions were doped to investigate the variations in the properties. X-ray diffraction (XRD), Field emission electron microscope (FESEM), and vibrating sample magnetometer (VSM) were used to investigate the structure, morphology, and magnetic properties of rare-earth doped NiZn nanoferrites, respectively. X-ray density, bulk density, and porosity were also calculated. Phase, crystallite size, structure, d-spacing, lattice parameter, micro strain, and...
A new modeling and control scheme for cascaded split-source converter cells
, Article IEEE Transactions on Industrial Electronics ; Volume 69, Issue 8 , 2022 , Pages 7618-7628 ; 02780046 (ISSN) ; Milimonfared, J ; Zolghadri, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Cascaded split-source inverter (CSSI) is a new single-stage modular multilevel topology. Each cell of this converter converts dc to ac power in the buck or boost operation mode without any additional power switch. This article develops a design method based on a detailed model for CSSI. This model shows that energy storage elements experience double-fundamental frequency ripples besides high-frequency ones. It accurately calculates voltage gains and capacitor voltage and inductor current ripples. On the other hand, common carrier-based multilevel modulations have been modified in terms of both reference and carrier signals to control the inverter under symmetric and asymmetric conditions....
Wide adjustable range LLC resonant converter's maximum switching frequency for realizing the ZVS operation
, Article Proceedings - 2010 18th Iranian Conference on Electrical Engineering, ICEE 2010, 11 May 2010 through 13 May 2010 ; 2010 , Pages 745-752 ; 9781424467600 (ISBN) ; Rashidian, B ; Zolghadri, M. R ; Alavi, M. H ; Sharif University of Technology
Abstract
In this paper, the FHA and a simple TDA approaches have been used to derive the normalized maximum switching frequency of wide adjustable range LLC resonant converter for realizing the ZVS operation even under the worst-case conditions. By accounting the resonant current higher harmonics, more accurate expressions are derived. These analyses demonstrate that the normalized maximum switching frequency depends on the dead-time and the converter inductance ratio. It also depends on the ratio of the converter resonant capacitor and the effective capacitance appeared in parallel with the power MOSFETs drain-sources. The simulated and experimental results are in good agreement with the derived...