فهرست مطالب

  • Volume:16 Issue: 1, 2020
  • تاریخ انتشار: 1398/12/10
  • تعداد عناوین: 13
|
  • S. Pourjafar, H. Shayeghi*, H. Madadi Kojabadi, M. Maalandish, F. Sedaghati Pages 1-12

    In this work, a non-isolated high step up DC-DC converter using coupled inductor and voltage multiplier cell is proposed. The proposed converter conversion ratio is efficiently extended by using a coupled inductor. An interleaved configuration of two diode-capacitor cells is applied to step up the voltage conversion ratio and decrease the voltage stress across the switches. Also, in the suggested converter high voltage gain is provided by low turn ratio of the coupled inductor which decreases the volume of cores. Moreover, the reverse recovery problem of output diode is diminished by recycling the leakage inductance energy of the coupled inductor. It causes to increase the overall system efficiency. Furthermore, the voltage multiplier cells lead to clamp the voltage spikes through the switch, when the switch turns off. The comparison between the suggested converter and similar converters is provided to verify its advantages. To validate the effectiveness of the suggested converter, a 200W laboratory prototype with 20V input and 150V output voltages operating at 25kHz switching frequency is carried out and experimental test consequences are given.

    Keywords: Non-Isolated Converter, High Conversion Ratio, Coupled Inductor, Voltage Multiplier Cell
  • H. Toodeji* Pages 13-25

    This paper proposes a hybrid switching technique for a domestic PV system with AC-module architecture. In this PV system, independent control of PV modules, which are directly connected to DC terminals of a single-phase cascaded multilevel inverter, makes module-level MPPT possible to extract maximum available solar energy, especially in partial shading conditions. As one of the main contributions, the proposed hybrid method employs a fundamental-based switching technique to decrease power losses, which directly affect the efficiency of solar energy conversion. In addition, fast dynamic response of the introduced hybrid technique lets the PV system to harvest more power in partial shading conditions. Producing a waveform with minimized THD in steady-state conditions is another advantage of the proposed switching technique. In this paper, the advantages of the proposed hybrid method are verified by the simulation of a test PV system with both conventional SPWM and proposed switching techniques in MATLAB/Simulink under various partial shading conditions.

    Keywords: Cascaded Multilevel Inverter, Fundamental Frequency Switching Technique, Single-Phase PV System, Switching Losses, THD Minimization
  • A. Jabbari*, F. Dubas Pages 26-38

    In this research work, an improved two-dimensional semi-analytical subdomain based method for performance computation in IPM machine considering infinite-/finite-magnetic material permeability in pseudo-Cartesian coordinates by using hyperbolic functions has been presented. In the developed technique, all subdomains are divided into periodic or non-periodic regions with homogeneous or non-homogeneous boundary conditions (BCs), respectively. Taking into account the appropriate interfaces conditions in the presented coordinates system, the machine performances including magnetic flux density, cogging/electromagnetic torque, back-EMF, and self-/mutual induction have been calculated for three distinct values of soft-magnetic material relative permeability (viz, 200, 800 and ∞). The semi-analytical results are compared and confirmed by the FEA results.

    Keywords: IPM Machine, Analytical Model, Soft-Magnetic Material Relative Permeability, Pseudo-Cartesian Coordinates, Subdomain-Based Technique
  • J. Rahmani Fard* Pages 39-47

    By combining the field-weakening control principle of a new axial flux-switching permanent-magnet motor (AFFSSPM) with the space vector pulse width modulation (SVPWM) and maximum torque per voltage (MTPV) control principle, a novel field-weakening control strategy for AFFSSPM is proposed in this paper. In the first stage of the field-weakening, the difference between the reference voltage updated by the current regulator and the saturated voltage output with SVPWM is used for field-weakening control, which modifies the direct axis of stator current. This method makes full use of the DC bus voltage, and can naturally smooth transition. In the second stage of the field weakening, the principle of MTPV control is used for field-weakening control, and then, being linearized. Compared with the traditional method, this method solves the problem of depth weakening of AFFSSPM. Between the two stages, the turning speed is used for the switch condition to achieve a smooth transition. The effectiveness and correctness of the proposed field-weakening control method and calculation method were verified with simulation results. Moreover, the dSPACE semi-physical simulation experimental platform for the hardware design and software design is used, and the semi-physical simulation experiment is carried out. The results show the accuracy and effectiveness of the proposed scheme.

    Keywords: Flux-Switching Permanent-Magnet Motor, Field-Weakening Control, MTPV, Stability
  • S. Mohamadian*, H. Azizi Moghaddam Pages 48-57

    Linear AC power supplies can be replaced by their nonlinear switching counterparts due to the lower voltage drops and higher efficiency and power density of switching-mode inverters. Multilevel cascaded H-bridge (CHB) converters are the preferred inverter structure because of modular configuration, control, and protection. The output voltage quality in CHB converters depends on the number of output levels. Asymmetric CHBs (ACHBs) produce an output voltage with higher number of levels with respect to CHBs for the same number of cascaded modules. This results in the reduction of power supply size, voltage drops, and losses. Considering the relative high switch counts, analysis of the effect of conduction and dead-time voltage drops on the inverter output characteristics is an important challenge in designing multilevel converters. In this paper, a generic algorithm is presented to calculate the conduction and dead-time voltage drops of ACHBs utilizing level-shifted modulation. These voltage drops give the necessary information for the design of heatsinks, switch selection, output impedance estimation, and the compensation schemes. It is shown through theoretical and simulation studies that the aforementioned voltage drops of ACHBs are to be calculated in a different manner with respect to the CHBs which mostly use the phase-shifted modulation.

    Keywords: ACHB, Conduction, Dead-Time Voltage Drops, Equivalent Impedance, Level-Shifted Modulation, Switching Pattern
  • A. N. Patel*, B. N. Suthar Pages 58-65

    Cogging torque is the major limitation of axial flux permanent magnet motors. The reduction of cogging torque during the design process is highly desirable to enhance the overall performance of axial flux permanent magnet motors. This paper presents a double-layer magnet design technique for cogging torque reduction of axial flux permanent magnet motor. Initially, 250 W, 150 rpm axial flux brushless dc (BLDC) motor is designed for electric vehicle application. Initially designed reference axial flux BLDC motor is designed considering 48 stator slots and 16 rotor poles of NdFeb type single layer permanent magnet. Three-dimensional finite element modeling and analysis have been performed to obtain cogging torque profile of reference motor. Additional layer of the permanent magnet is created keeping usage of permanent magnet same with an objective of cogging torque reduction. Three-dimensional finite element modeling and analysis have been performed to obtain cogging torque profile of improved axial flux BLDC motor with double layer permanent magnet design. It is analyzed that double-layer magnet design is an effective technique to reduce the cogging torque of axial flux BLDC motor.

    Keywords: Cogging Torque, Axial Flux BLDC Motor, Finite Element Analysis, Double-Layer Magnet
  • D. Kishan*, P. S. R. Nayak, B. Naresh Kumar Reddy Pages 66-73

    In recent years, the popularity of wireless inductive power transfer (WIPT) system for electric vehicle battery charging (EVBC) is always ever-increasing. In the WIPT inductively coupled coil structure is the heart of the system and the mutual inductance (MI) between the coupled coils is the key factor for effective power transfer. This paper presents the analysis of mutual inductance between the spiral square coils based on the cross-sectional area ratio of spiral circular and spiral square coupled coils. The analytical computed MI values are compared with FEM (Ansys Maxwell) simulation and Experimental computed values. Finally, the designed spiral square coils are implemented in a laboratory prototype model and at the receiver side for effective electric vehicle (EV) battery charging a closed-loop PID controller is implemented for DC-DC buck converter. The effectiveness of the proposed controller has been tested by providing sudden changes in mutual coupling and change in reference value. The proposed system is suitable for both stationary and dynamic wireless EVBC.

    Keywords: Inductive Power Transfer, Battery, Electric Vehicle, Mutual Inductance
  • H. Shadfar, H. R. Izadfar* Pages 74-84

    Single-phase induction motors have a wide range of domestic and industrial applications. These motors have a squirrel cage rotor and their stator usually has two windings: main and auxiliary. The use of auxiliary winding in the structure of single-phase induction motors creates two unbalance and asymmetric phases. This causes to increase the spatial harmonics of the field in the air gap, and also useless electromagnetic forces. The purpose of this paper is the reduction of the electromagnetic forces in single-phase induction motors, focusing on the effect of the stator winding distribution. For this purpose, two new and different winding distributions for the motors used in the water coolers will be provided. The produced electromagnetic forces in several conventional single-phase induction motors will be compared with new and conventional windings by means of numerical methods. Numerical analysis is performed by Maxwell software. The results of this analysis indicate improvements in the quality of the performance of these motors in the presence of the provided windings.

    Keywords: Auxiliary Winding, Electromagnetic Noise, Main Winding, Single-Phase Induction Motor, Squirrel Cage Rotor, Starting Torque
  • B. Yassine*, Z. Fatiha, L. Chrifi Alaoui Pages 85-95

    This paper suggests novel sensorless speed estimation for an induction motor (IM) based on a stator current model reference adaptive system (IS-MRAS) scheme. The IS-MRAS scheme uses the error between the reference and estimated stator current vectors and the rotor speed. Observing rotor flux and the speed estimating using the conventional MRAS technique is confronted with certain problems related to the presence of the pure integrator and the rotor resistance causing offsets at low speeds, as proved by the most recent publications. These offsets are disastrous in sensorless control since these signals are no longer suitable to calculate of park angle (θs). This paper discusses the new MRAS approach (IS-MRAS) for on-line identification of the rotor resistance suitable for compensating offsets and solving problems of ordinary MRAS at low speed. This new MRAS approach used to estimate the components of the rotor flux and rotor speed without using the voltage model with on-line Setting parameters (Kp, K1) based on Type-2 fuzzy Logic. The results of the simulation and the experimental results are presented and show the effectiveness of the proposed technique.

    Keywords: Induction Motor, IS-MRAS, Type-2 Fuzzy logic, Sensorless Control
  • M. S. Hosseini, H. Javadi*, S. Vaez Zadeh Pages 96-106

    Linear flux switching motors with simple passive segmented secondary, referred as Segmented Secondary Linear Flux Switching Motors (SSLFSMs), have low cost secondary and therefore are applicable to transportation systems like Maglev. However, it is shown that the SSLFSMs suffer from high thrust ripples. In this paper, minimizing SSLFSM thrust ripples besides maximizing its developed thrust are performed by considering the motor dimensions as design variables. Since the optimization of the motor is a high dimensional problem, a multi-level optimization method is employed to improve the machine performances and efficiency. According to the effects of the design variables on the optimization objectives, a sensitivity analysis is carried out to divide the design variables into two levels: mild-sensitive level and strong-sensitive level. Then, the two levels of design variables are optimized based on a mathematical model. Two different optimization methods as the Design of Experiment (DOE) and the Response Surface Method (RSM) are used in mild-sensitive level and the Genetic Algorithm (GA) is also used in strong-sensitive level. Based on FEM analysis, electromagnetic performance of the original motor and the optimal one are compared and the validity of the proposed optimization method is verified. Also, the effectiveness of the mathematical model used in thrust and thrust ripples calculations is evaluated and verified.

    Keywords: Linear flux Switching Motors, Multi-Level Optimization, Response Surface Methodology, Sensitivity Analysis Method, Thrust Ripples Minimization
  • F. Masoudina, E. Babaei*, M. Sabahi, H. Alipour Pages 107-113

    In this paper, a new structure for cascade multilevel inverter is presented which consists of a series connection of several sub-multilevel units. Each sub-multilevel unit comprises of eight unidirectional switches, two bidirectional switches, and six DC voltage sources. For the proposed cascade topology, two algorithms are presented to produce all possible levels at the output voltage waveform. The required analysis of the voltage rating on the switches is provided. In order to verify the performance of the proposed inverter, the experimental results for a 15-level inverter are provided. The experimented 15-level inverter is compared with the other presented inverters in literature in terms of the number of DC voltage sources, switches, drivers, and blocked voltage by switches. The results of comparisons indicate that the experimented 15-level inverter requires lower power electronic elements. Moreover, the blocked voltage on the switches of the proposed topology is less than other topologies.

    Keywords: Multilevel Inverter, Blocked Voltage, Harmonic Distortion, Fundamental Frequency Switching
  • A. Nobahari, M. R. Mosavi*, A. Vahedi Pages 114-121

    A methodology is proposed for optimal shaping of permanent magnets with non-conventional and complex geometries, used in synchronous motors. The algorithm includes artificial neural network-based surrogate model and multi-objective search based optimization method that will lead to Pareto front solutions. An interior permanent magnet topology with crescent-shaped magnets is also introduced as the case study, on which the proposed optimal shaping methodology is applied. Produced torque per magnets mass and percentage torque ripple are considered as the objectives, in order to take both performance and cost into account. Multi-layer perceptron architecture used to create the approximated model is trained to fit the samples collected via time-stepping finite element simulations. The methodology can be easily generalized to offer a fast and accurate method to optimally define arbitrary permanent magnet shape parameters in various synchronous motors.

    Keywords: Permanent Magnet Shaping, Surrogate Model, Artificial Neural Network, Multi-Objective Optimization
  • H. Davari, Y. Alinejad Beromi* Pages 122-129

    In this paper, at first, a 24/16 three-phase switched reluctance motor is designed, then the rotor poles shape tips corrected for reduction ripple of single-phase torque waveform. By doing this, the single-phase torque waveform has a flat surface and consequently, the single-phase torque ripple is reduced. Also, due to the commutation between the machine phases, the torque drops during this time, which are known as torque pits. To reduce the ripple torque at these points, which requires overlap between the two successive phases of the machine, the pulse width of the excitation of the machine phases is adjusted. Comparisons have been made between two types of direct current excitation and chopped current (with different pulse widths). The results show that for constant pulse width under chopped current, applying the arc and modifying the shape of the rotor poles can reduce the torque ripple by 3.4%. Also, by applying chopped current control, the torque ripple was reduced by 46.7% compared to its conventional design structure.

    Keywords: Non-Uniform Air Gap, Pole Shape, Switched Reluctance Motor, Torque Ripple