Sharif Digital Repository

In this paper, a novel zero-voltage-switching topology for power factor correction bridgeless boost rectifier is proposed. By employing an improved switch cell, ZVS for all the main switches is achieved without additional current or voltage stress. The zero-current-switching is also provided for the auxiliary switch. In all modes of operation of this converter, the input current flows through only two semiconductors. Therefore, conduction loss of this converter is as low as the conventional parent converter. With these features, the efficiency of the proposed converter is very high. A 500 W prototype is designed and simulated to verify the system performance  

Plug-In hybrid electric vehicles could be connected to the electrical grid to be recharged. To ease the charging process, one solution could use an on-board charger to charge the electric vehicle battery. This charger should be able to be connected to a conventional outlet for convenience reasons and moreover, it should be a grid friendly charger in order not to pollute the electrical network. Since most of the electric vehicle related projects are at their initial phases, keeping up with the pace and developing new technologies and proposing innovations and concepts will help growing the industry. In this regard, a new integrated bidirectional isolated soft-switched plug-in hybrid electric... 

Servo drive systems require a fast dynamic response for position control applications. Conventional cascade control structure has sluggish response due to bandwidth limitations on speed and current control loop. To achieve a fast output response, model reference adaptive control methods can be used to remove the dynamics of inner control loops. In this paper, feed-forward signals are generated using model predictive control which is combined with the conventional cascade structure. Using this approach, a fast transient response and satisfactory tracking ability can be achieved. The proposed control configuration is verified by the simulation results  

Electric vehicles have been proposed as a proper replacement for fossil fuel-powered vehicles; however, due to the limited power density of electric vehicles batteries, these cars have been facing formidable challenges, such as limited traversed distance. In recent years, dynamic wireless chargers are introduced as an adequate way of addressing this problem in the hope that dealing with this issue can lead to an increase in the popularity of electric vehicles. In this paper, a design procedure for transmitter coil of a dynamic wireless electric vehicles charger is proposed. The procedure includes selecting the best possible shape and calculating optimum size of coils for proper operation of... 

Control of Synchronous Motors at low speed has been the topic of several studies for the last years. Due to the lower amplitude of Back-EMF voltage in lower speed, it is inappropriate to merely rely on induced voltages for position estimation. In this paper, a new double carrier PWM modulation is presented in which two carrier frequencies are utilized for two legs of the inverter. This proposed method rectify the need of powerful processors which decreases the cost of the electric drive system. Employing a non-linear control system and an automatic gain control, ensures the sensorless control of the motor for a wide range of speed. © 2019 IEEE  

Islanding occurs when a utility-interactive distributed generator (DG) is disconnected from the utility grid and continues to supply power to local loads. This condition has several consequences including damage to the equipment and personnel safety risks. Therefore, it is required by utility interconnection standards for the DG to stop energizing local loads in the case of islanding. In this paper, an active islanding detection method (IDM) based on injecting a disturbance into the phase-locked loop (PLL) of a grid-connected photovoltaic (PV) inverter and monitoring the harmonic components of the point of common coupling (PCC) is proposed. A modified Goertzel algorithm is utilized to detect... 

Resonant LLC converter is a preferred candidate for emerging electric vehicle (EV) applications, thanks to its high efficiency and high power density characteristics, which are achieved due to high switching frequency and soft-switching operation. On the other hand, planar transformers (PTs) for EVs offer power density in a small package and withstand vibrations. However, large parasitic capacitance is a characteristic of PT, which along with the large dv/dt of the converter leads to severe conducted emission problems. Therefore, multifold complicated and bulky electromagnetic interference (EMI) filters are required to suppress conducted noise and meet the requirements of the relevant... 

Although permanent magnet synchronous motors (PMSMs) are inherently of high efficiency, their efficiency is enormously dependent on their control strategy. The purpose of this paper is to improve the efficiency of PMSMs under a direct torque control (DTC) method. The main idea behind the proposed method is to predict a required small change of the statorflux amplitude at each sampling period to reduce the machine electrical loss before the change is applied. Accordingly, at every sampling time, a voltage vector is predicted and applied to the machine to change the flux amplitude in a xvay that the electrical loss decreases. The results of simulation show significant improvement in the... 

The main purpose of this paper is to minimize the loss while reducing the flux and torque ripples in permanent magnet synchronous motors (PMSMs) under direct torque control (DTC). Offline method is used to minimize the loss and obtain the optimal flux. To reduce the amount of computation, the optimal flux table is produced according to the conditions in which the machine works. To reduce the flux and torque ripples and to control the switching frequency, SVM-DTC method is applied. Simulation results depict a noticeable increase in efficiency of the motor and a reduction in flux and torque ripples  

The main objective of this a paper is to improve the efficiency of permanent magnet synchronous motors (PMSMs) by using an improved direct torque control (DTC) strategy. The basic idea behind the proposed strategy is to predict the impact of a small change in the stator flux amplitude at each sampling period to decrease electrical loss before the change is applied. Accordingly, at every sampling time, a voltage vector is predicted and applied to the machine to fulfill the flux change. The motor drive simulations confirm a significant improvement in efficiency as well as a very fast and smooth response under the proposed strategy  

Battery and plug-in hybrid vehicles equipped with bidirectional battery chargers are capable of supplying power to the electric grid according to power system demand. This technology is called 'vehicle to grid' or V2G. A bidirectional on-board charger can be used to improve the charge availability. An on-board charger should have small size and light weight. On the other hand, the charger must minimize power quality impact, draw current at high power factor to maximize power from an outlet. In this paper, a new three-phase integrated bidirectional isolated soft-switched battery charger is proposed which is appropriate for vehicle to grid technology. The charger utilizes a 4-switch... 

Battery chargers are fundamental components for successful deployment of plug-in hybrid electric vehicles (PHEVs) into future smart grid. Recently, an integrated isolated bidirectional battery charger has been proposed for PHEV applications. The proposed charger eliminates the conventional bulky dc-link capacitor by feeding a dual-bridge resonant tank directly from the three-phase grid. The disadvantages associated with the presented charger are the high number of semiconductor switches which contribute to high cost and switching losses of converter as well as complicated control circuitry. In this paper, the previous structure is modified to address the aforementioned drawbacks and is... 

Plug-in hybrid electric vehicles draw electricity from the electrical grid and store energy in their batteries. To increase charge availability for plug-in hybrid electric vehicles, on-board chargers can be used, which should be small in size and lightweight. In this article, an on-board bidirectional soft-switched battery charger is proposed that utilizes a phase-shift-controlled dual-bridge series resonant converter with isolation. The bidirectional characteristic of proposed charger makes it suitable for vehicle-to-grid operation (i.e., injecting power from the vehicle to the grid) in smart grids. A switching control scheme is also proposed to provide soft-switching operation for all... 

This paper proposes a straightforward control method for voltage control of a three-phase transformer-based inverter in uninterruptible power supplies or distributed generation systems. The approach offers a dual-loop design consisting inner current control loop and outer voltage loop. Sliding mode current controller provides desired bandwidth for voltage controller which consists of a state feedback term for stabilization and resonant term for harmonic damping. The proposed scheme provides fast dynamic response and low total harmonic distortion even for high power inverters with the limitations of switching frequency and LC filter components. Experimental studies for 2KVA linear and... 

Depending on the reference frame, a proportional integral (PI) or proportional resonant (PR) controller is often utilized for current control in the three-phase PWM rectifiers. Due to the fact that the controller bandwidth is either smaller than the frequency of a specific order harmonic or the controller gain at that frequency is too low the harmonics cannot be effectively eliminated. Among all approaches introduced for harmonic elimination, selective harmonic compensation is believed to have a better performance. Selective harmonic compensation can successfully compensate for harmonics. It, however, forces a considerable computation burden on DSP. This paper proposes a new compensation... 

Power density is an influential factor in 400 volt telecom energy distribution systems. In addition, systems are desired to reach an acceptable efficiency while they take advantage of a galvanic isolation. This paper presents a new architecture that is based on push pull topology and its power switches perform ZVS in both their turn on and turn off conditions. Besides, the presented topology uses an interleaving technique that has made it desirable for high power applications. Power loss for the presented topology is calculated and compared to conventional topologies. Finally, by considering the efficiency and power density of the presented topology, it is concluded why this topology is... 

This paper investigates a predictive control strategy for a single-phase PFC rectifier exploiting the Sheppard-Taylor converter. By using this converter, the detuning problem occurring in conventional PFC rectifiers, especially at low input voltages, is avoided. This paper addresses a predictive method for designing the current controller of the Sheppard-Taylor PFC converter. The control law is derived for an ideal circuit as well as a more accurate model of the converter including parasitic elements. Input voltage feed-forward compensation provides sinusoidal input current and a desired output voltage even if the input voltage is distorted. To investigate the dynamic performance of the PFC... 

A dc-dc resonant converter has the advantage of overcoming switching losses and electromagnetic interference which are the main limitations of high frequency power converters. Nevertheless, the modeling and stability analysis of dc-dc resonant converters are considerably more complex than pulsewidth modulation counterparts. The conventional averaged linearized model of the resonant converter has limitations due to averaging and linearization. First of all, the linearized model has large modeling error in presence of large variations of reference voltage and input voltage. Furthermore, Converging area for stabilizing controllers is smaller in the averaged model. In order to overcome these... 

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... 

This paper offers a new EF-class converter for dynamic wireless power transfer application. The proposed high-frequency converter employs a floating-frequency switching algorithm to control the converter in a continuous frequency range, eliminate the requirement to any additional operational data from the secondary (receiver) side, accelerate the load impedance match while moving, maximize the transferred power rate, reduce charging interval and compensate power transfer tolerances. Moreover, an optimized super elliptical shape coil is designed to cope with lateral misalignment, enhance coil coupling, and increase efficiency. In the proposed converter, (i) soft switching is implemented to...