Industrial Electronics
Ebrahim Taghvayi; Mohammad Reza Karafi
Abstract
In this paper, a new method is developed to detect and track the resonance frequency of ultrasonic transducers. In order to have an acceptable performance of transducers, power supplies should be able to detect and track the resonance frequency. Different methods have been used for this purpose. In this ...
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In this paper, a new method is developed to detect and track the resonance frequency of ultrasonic transducers. In order to have an acceptable performance of transducers, power supplies should be able to detect and track the resonance frequency. Different methods have been used for this purpose. In this research, the voltage of the transducer and the phase difference between the voltage and current are used to find the resonant frequency. The maximum voltage of a transducer is founded in a predefined frequency interval. Afterward, the minimum phase difference between the voltage and current is obtained in a smaller interval around it. The simultaneous use of the voltage and phase shift increases the accuracy and speed of the algorithm. Since the transducer's voltage variations are relatively large near the resonant frequency, it is a versatile parameter compared to the current used in other methods to indicate the resonance frequency. The algorithm is implemented within a microcontroller. An FPGA is used to generate accurate frequency using the Direct Digital Synthesis (DDS) method. The algorithm can detect the resonant frequency under free conditions. Applying force to transducers or emerging the transducer's head to the water changes the resonant frequency. The experimental tests showed that the algorithm could find and track the resonant frequency automatically under loading conditions.
Industrial Electronics
Roya Naderi; Ebrahim Babaei; Mehran Sabahi; Ali Daghigh
Abstract
This work proposes a new multilevel inverter consisting of basic and submultilevel units. The basic unit is made-up of four isolated dc voltage sources, two bidirectional switches and ten unidirectional switches. To increase the number of the output voltage levels, a cascaded architecture based on series ...
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This work proposes a new multilevel inverter consisting of basic and submultilevel units. The basic unit is made-up of four isolated dc voltage sources, two bidirectional switches and ten unidirectional switches. To increase the number of the output voltage levels, a cascaded architecture based on series connection of sub-multilevel is proposed. The proposed inverter utilizes two algorithms to determine the values of dc voltage sources. Number of IGBTs, dc voltage sources, gate driver circuits, variety of dc voltage sources and peak standing voltage on the switches are calculated and their optimization to produce maximum number of levels in output voltage is investigated. To examine advantages of the proposed inverter, the topology is compared with other topologies. The results show superiority of proposed topology over most conventional topologies, in number of circuit components. Finally, to confirm the performance of the proposed multilevel inverter, experimental results of a 25-level inverter prototype are provided.
Industrial Electronics
Mohsen Feizi; Reza Beiranvand; Mahdi Daneshfar
Abstract
Conventional energy storage systems (ESSs) such as super-capacitors and lithium-ion batteries require voltage equalization systems to eliminate voltage imbalances, and bidirectional dc-dc converters to complete the charging process. These separated systems require some sensors, inductors, switches, and ...
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Conventional energy storage systems (ESSs) such as super-capacitors and lithium-ion batteries require voltage equalization systems to eliminate voltage imbalances, and bidirectional dc-dc converters to complete the charging process. These separated systems require some sensors, inductors, switches, and transformers. Consequently, the ESSs volumes, prices, and their complexity are dramatically increased by increasing the required series connected batteries count. Here, a self-equalized battery charger is proposed for lithium-ion batteries by combining a voltage multiplier (VM) and a phase-shifted full-bridge (PSFB) dc-dc converter. In the proposed self-equalized battery charger, the voltage multiplier eliminates the voltage imbalances and the PSFB dc-dc converter carries out the charging process. By combining the voltage equalizing and the charging systems into a single system, an integrated converter is obtained which leads to simultaneous charging and equalization operations, power and control sections simplicity, as well as low volume and price. By utilizing the phase-shift control method, zero-voltage-switching (ZVS) operation of power MOSFETs is obtained which leads to high efficiency and low EMI noise. The experimental results for 8 battery modules including 48 lithium-ion cells, are in good agreement with the given mathematical analyses and simulations and clearly show the simultaneous charging and voltage equalizing operations, as well.
Industrial Electronics
Taher Ahmadzadeh; Ebrahim Babaei; Mehran Sabahi; Taher Abedinzadeh
Abstract
< p>In power converters, the total harmonic distortion (THD) can be decreased by using two strategies which are filtering and controlling methods. The filtering strategy is indeed costly because of using hardware devices (such as capacitor and inductor). A suitable strategy to control the modern ...
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< p>In power converters, the total harmonic distortion (THD) can be decreased by using two strategies which are filtering and controlling methods. The filtering strategy is indeed costly because of using hardware devices (such as capacitor and inductor). A suitable strategy to control the modern power converters without using the hardware devices is the pulse width modulation (PWM) technique. In this paper, three new PWM control methods based on mathematical equations for various Z-source inverters (ZSIs) are proposed. Controlling the duty cycles of switches is the basic idea of these methods to control the output voltage. The proposed control methods are analyzed under the circumstances of constant input and balanced output voltage (CIBOV) and ripple input and balanced output voltage (RIBOV). The advantages of proposed methods are control of voltage, current and harmonic distortion. Other advantages of these methods are lower value for THD and elimination of low-order harmonics. The correctness operation of the proposed PWM techniques is proved by using the simulation results.
Industrial Electronics
Gholamreza Mohebalizadeh; Hasan Alipour; Leila Mohammadian; Mehran Sabahi
Abstract
Abstract- An Electric Vehicle Battery Charger (EVBC) faces serious challenges as continuous charging voltage ripple, charging speed, input voltage level variations, and its ability to adapt to the Battery State of Charge (BSOC). A proper controller has an important role to prepare all the mentioned above. ...
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Abstract- An Electric Vehicle Battery Charger (EVBC) faces serious challenges as continuous charging voltage ripple, charging speed, input voltage level variations, and its ability to adapt to the Battery State of Charge (BSOC). A proper controller has an important role to prepare all the mentioned above. A nonlinear one such as sliding mode controller (SMC) is eminently suitable for solving these issues. Therefore, an improved SMC, to take control of a DC/DC boost converter as an EVBC, is presented in this work. This proposed controller has a more robust structure in the input voltage significant variations than the other SMCs. Therefore, this provides the capability to apply various kinds of power supplies as input voltages in EVBC stations. The EVBC power and battery voltage/capacity are assumed 14 kW and 400V/60Ah, respectively in this converter. The simulation results in Matlab Simulink verify the controller’s high performance compared with the other SMCs.
Industrial Electronics
Mehran Jami; Qobad Shafiee; Hassan Bevrani
Abstract
In this paper, a virtual inertia control strategy based on linear feedback is presented that improves dynamic behavior of islanded dc microgrids interfaced with constant power loads (CPLs). In order to solve the stability challenges caused by low inertia and CPLs, the proposed control scheme is composed ...
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In this paper, a virtual inertia control strategy based on linear feedback is presented that improves dynamic behavior of islanded dc microgrids interfaced with constant power loads (CPLs). In order to solve the stability challenges caused by low inertia and CPLs, the proposed control scheme is composed of a virtual capacitor and a virtual conductance. It is implemented in the inner loop control, i.e. current loop control to be fast enough emulating inertia and damping concept. In addition, the droop characteristic is modeled by using the virtual resistance which adjusts the steady-state response of the system. In this study a multi-level structure is considered, which comprises the source level, interface converter level, and common load level. In addition, an accurate small-signal model is used to investigate the stability of dc MG interlaced with CPLs, and then, an acceptable range of inertia response parameters is determined by using the root locus analysis. Performance of the proposed control structure is demonstrated through numerical simulations.
Industrial Electronics
Seyed Reza Mousavi-Aghdam; Amin Kholosi
Abstract
This paper presents a novel topology of permanent magnet brushless DC motors. Brushless DC motors usually experience torque ripple mainly caused by cogging torque. In the proposed motor, the whole structure of the rotor’spermanent magnets hasbeen changed so that the cogging torque is considerably ...
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This paper presents a novel topology of permanent magnet brushless DC motors. Brushless DC motors usually experience torque ripple mainly caused by cogging torque. In the proposed motor, the whole structure of the rotor’spermanent magnets hasbeen changed so that the cogging torque is considerably mitigated. The philosophy behind this modification depends on the way of flux-path production in the rotor structure and it should be similar to the way of motor phases. Aninitial electromagnetic analysis is, first,carried out using the finite element method. Asensitivity analysis is, next,included to obtain the most important design parameters for the proposed structure. The different performance parameters of the motor are calculated and compared betweenthe proposed structures and the conventional BLDC structures. The results revealthat the proposed motor has a considerably lowertorque ripple retaining an average value of the produced torque. The proposed structure is also compared with an asymmetrical V-type structure and the results further show the effectiveness of the proposed structure.
Industrial Electronics
Homayon Soltani Gohari; Karim Abbaszadeh; Jafar Gholami Gorji
Abstract
Finding effective solutions to enhance the process of electric vehicles’ charging is the main subject of numerous studies. In this paper, a novel bidirectional multiport rectifier has been presented which can be used as a wall-box converter that is installed in the parking lot of smart buildings ...
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Finding effective solutions to enhance the process of electric vehicles’ charging is the main subject of numerous studies. In this paper, a novel bidirectional multiport rectifier has been presented which can be used as a wall-box converter that is installed in the parking lot of smart buildings and is able to provide DC-link for local DC loads such as DC home appliances and charge connected EV, simultaneously. The proposed converter is capable of working in G2H/G2VH/V2H/V2G modes which enables the utility grid and costumer to use the EV as a mobile power source and reactive power compensator. A control method is also presented which enables the converter to control active and reactive power according to the smart grid or customer processed commands. In order to validate features of the proposed converter, it is simulated in MATLAB/SIMULINK and results are analyzed. A reduced-scale experimental setup of the proposed converter is built and tested and experimental results confirm simulation ones.
Industrial Electronics
Asghar Taheri; Amir Ghasemian
Abstract
A direct torque control (DTC) controlled induction motor drive is presented in this paper. Quantization errors of current and voltage measurements are simulated and considered. To reduce the average quantization error and other offset errors of current and voltage measurement and eliminating the increasing ...
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A direct torque control (DTC) controlled induction motor drive is presented in this paper. Quantization errors of current and voltage measurements are simulated and considered. To reduce the average quantization error and other offset errors of current and voltage measurement and eliminating the increasing integrator errors, a random dither signal is added to the truncating analog to digital converter (ADC) outputs. In this method, the analog to digital converter (ADC) mean error is reduced to zero and therefore integrator output error is mitigated. Proposed quantization method can improve the digital converter result, thus this method can decrease the current measurement result. Proposed quantization method can improve the digital converter result, thus this method can decrease the current measurement result. Thus, the torque and flux ripple were be decreased. Proposed ditter injection method can be used in Digital signal processor (DSP) or FPGA implemented applications. Experimental results show the performance of proposed method.
Industrial Electronics
Hamid Radmanesh; Masood Saeidi
Abstract
The AC/DC converter is one of the popular power electronic converters in industrial applications such as in the railway, power supply systems and electric vehicle. In this paper, a three-phase controllable rectifier is considered and its linear model is extracted. Because of MPC controllers benefits, ...
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The AC/DC converter is one of the popular power electronic converters in industrial applications such as in the railway, power supply systems and electric vehicle. In this paper, a three-phase controllable rectifier is considered and its linear model is extracted. Because of MPC controllers benefits, the continuous control set model predictive controller (CCs-MPC) is designed for controlling this rectifier output DC voltage. By considering rectifier dynamic response, the suitable criteria to choice the model predictive controller parameters such as sampling time, prediction horizon and control horizon is proposed. In experimental implantation the computing burden of microcontroller is limit therefore the reaching to optimal and minimum complexity in algorithms implantation is vital problem. In other words by using these proposed criteria for selection of sample time, prediction and control horizon the tradeoff between computational burden, system performance and dynamic stability is made. When using designed MPC controller, the rectifier and grid performance such as total harmonic distribution (THD), power factor (PF) and output voltage ripple have acceptable value. This controller can eliminated the effect of heavy load change on rectifier performance which is very common problem in indusial system. Also, this controller stability guaranteed is checked by using the dual-mode method. The simulation results are validated by using MATLAB software and showing the designed controller performance.
Industrial Electronics
Alireza HossienPour; Reza Ghazi
Abstract
Harmonic reduction is an essential issue in a grid-connected variable-speed wind energy conversion system to decrease the electrical losses of the system and improve the power quality. In this paper, a new Shunt Active Filter (SAF) based on a three-phase four-switch inverter is used to improve the output ...
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Harmonic reduction is an essential issue in a grid-connected variable-speed wind energy conversion system to decrease the electrical losses of the system and improve the power quality. In this paper, a new Shunt Active Filter (SAF) based on a three-phase four-switch inverter is used to improve the output current harmonics of the wind energy conversion system. The SAF contains three parts: identification, modulation, and inverter. In the proposed filter, an identification algorithm, which is not sensitive to the input source harmonic, is used to cancel out most harmonics impact. Moreover, a modified modulation technique based on the identification of the output signal is utilized. In the previous active filters, a three-phase six-switch inverter has often been used; however, in the proposed SAF, the number of switches is decreased to four in order to decrease the inverter losses. Simulation results confirm the superior performances of the proposed active filter versus the prior one for a wind energy conversion system.
Industrial Electronics
seyed Hamid shahalami; Farzin Rajab Nejad
Abstract
In this paper, the DC-DC boost converter in chaos mode is controlled using the adaptive Back-stepping method. One of the main features of power electronic converters is their nonlinear behavior due to existence of nonlinear elements such as diodes, switches, comparator and limiters in control circuits. ...
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In this paper, the DC-DC boost converter in chaos mode is controlled using the adaptive Back-stepping method. One of the main features of power electronic converters is their nonlinear behavior due to existence of nonlinear elements such as diodes, switches, comparator and limiters in control circuits. Different types of non-linear behaviors such as bifurcation and chaos may occur in power electronic converters. These undesirable behaviors reduce efficiency of converters greatly and also cause dielectric losses, copper losses, undesirable sound noises and system failure. Back-stepping method is one of the common nonlinear techniques for controller design. This method is capable of generating an asymptotic and stabilizing control law in order to suppress chaos and synchronize chaotic systems. Also, optimal controller coefficients are determined using Chaotic Particle Swarm Optimization algorithm. By selecting an objective function, parameters of the back-stepping controller are determined using CHPSO algorithm. The system with adaptive Back-stepping controller is compared with the optimized adaptive back-stepping controller.
Industrial Electronics
saeed danyali; Leila Moteiri
Abstract
Nowadays, using the photovoltaic powered LED street lights are spreading due to their higher efficiency and longer lifetime. In this paper, the Zeta-Sepic converter is used to manage the LED light, the PV panel and a battery storage in these systems, since it offers compact and single-stage power conversion. ...
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Nowadays, using the photovoltaic powered LED street lights are spreading due to their higher efficiency and longer lifetime. In this paper, the Zeta-Sepic converter is used to manage the LED light, the PV panel and a battery storage in these systems, since it offers compact and single-stage power conversion. The PV panel and LED light connect to the converter input port using simple relay, while the battery source puts at the converter output port. During the day, the PV panel energy saves in the battery through the converter forward direction power flow. Besides, in the reverse direction power flow of the converter the battery supplies the LED light required power during night. For these operation cases, voltage regulation is realizable at the both converter input and output ports. This performance provides MPPT to the PV panel, SOC for the battery and light control with the LED light. For LED lights, there exist a relationship between light, electricity and thermal that is optimized to achieve the luminal flux to the input power highest ratio. As a result, this paper uses the photo-electro-thermal theory, heatsink characteristics and bidirectional Zeta-Sepic converter to drive the LED lights at the operating voltage, in which the LED light optimal luminous flux occurs. Finally, the proposed system is analyzed and validated in different operation conditions using MATLAB/SIMULINK. Also, photo collector sphere was built in the laboratory that is able to achieve the optimal working point of the light by measuring the photo through sensors installed on it.
Industrial Electronics
Navid Rasekh; Majid Hosseinpour
Abstract
In the grid-tied PV inverter systems, the design of a proper power conditioning system is an important issue to ensure high-quality power injection to the grid. Among various control methods for grid-interfacing inverter with LCL filter, converter-side current feedback (CCF) method has been widely used ...
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In the grid-tied PV inverter systems, the design of a proper power conditioning system is an important issue to ensure high-quality power injection to the grid. Among various control methods for grid-interfacing inverter with LCL filter, converter-side current feedback (CCF) method has been widely used due to its inherent resonance damping feature. Applying the CCF method requires extra attention to the delay effect of the control system. In such systems, the delay narrows stability region of resonance frequency of the CCF control method, especially, in the presence of wide variations of the grid inductance. Adequate tuning of the LCL filter and consequently the proper choice of the resonance frequency can remarkably affect the performance of the CCF control. In this paper, a tuning procedure for LCL filter has been proposed. Mathematical tuning of the Proportional Resonant (PR) controller parameters has also been included to avoid typical trial and error procedures of tuning. Simulation of the overall system also includes solar panels, maximum power point tracking algorithm, Modified-Y-Source inverter, and LCL filter to model the grid-tied PV system with the most possible details. Simulations are carried out in MATLAB/Simulink and it has been proved that the proposed control system maintains its stability against grid parameters variations.
Industrial Electronics
Shima Tavakoli; Zahra Nasiri-Gheidari
Abstract
Static eccentricity (SE) is an intrinsic fault existing in both faulty and newly made resolvers. The late diagnosis of SE causes severe damages to mechanical parts of resolver such as bearings, cores and even windings, in addition to wrong position estimation. However, so far fault diagnosis has not ...
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Static eccentricity (SE) is an intrinsic fault existing in both faulty and newly made resolvers. The late diagnosis of SE causes severe damages to mechanical parts of resolver such as bearings, cores and even windings, in addition to wrong position estimation. However, so far fault diagnosis has not been investigated for any Resolver. In this paper, SE fault diagnosis is discussed for a sample wound-rotor (WR) cylindrical resolver. Time stepping finite element method (TSFEM) is used to simulate the resolver, and its accuracy is validated by a comparison between the results of simulation and experimental tests. Then, some fault indices are defined to diagnose the SE fault occurrence, and its magnitude is predicted using Fast Fourier transform (FFT). Finally, to ensure that indices are unique, the performance of the studied resolver is evaluated under other types of faults including Dynamic Eccentricity (DE) and Short-circuit (SC) that may excite the same indices.
Industrial Electronics
Mohsen Ehsani; Masood Saeidi; Hamid Radmanesh; Adib Abrishamifar
Abstract
In this paper, the linear state-space model of the multi-input DC-DC boost converter is obtained and based on, a linear SISO model is calculated. Model predictive control (MPC) offers a novel method of designing in the power electronic converters. The application to DC-DC converters offers real benefits ...
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In this paper, the linear state-space model of the multi-input DC-DC boost converter is obtained and based on, a linear SISO model is calculated. Model predictive control (MPC) offers a novel method of designing in the power electronic converters. The application to DC-DC converters offers real benefits because of having simple tuning technique and analytical guaranteed stability. The weakness of this converter is non minimum phase behavior. One of the methods of implementation MPC controller is Generalized Predictive Control (GPC) which is compatible with non-minimum phase systems but due to simple implementation, using of the linear controller is more popular in power electronics control system. GPC has some advantage such as fast dynamic and robustness in the nonlinear system however main advantage of linear controllers is its low steady state error. The main idea of this paper is the investigation performance of GPC and linear controller in the multi-input DC-DC boost converter and camper with PI controller in term of dynamic, steady-state error, and robustness and run time in a microcontroller. The resulting of this comparison is critically assessed in simulation and algorithms ruining time has been compared in microcontroller hardware.
Industrial Electronics
Alireza Karbalaei; Mohammad Mardaneh; Mokhtar Shasadeghi
Abstract
In this paper, a new topology of switched-inductor/capacitor quasi impedance source inverter is suggested, which in comparison with the other topologies possesses higher boost voltage inversion at high modulation index and low shoot through duty cycle. Also, this topology has features like continuous ...
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In this paper, a new topology of switched-inductor/capacitor quasi impedance source inverter is suggested, which in comparison with the other topologies possesses higher boost voltage inversion at high modulation index and low shoot through duty cycle. Also, this topology has features like continuous input current, common ground between the input source and the inverter bridge and, low shoot-through current. To express the proposed topology properties, it is compared experimentally in similar conditions relative to the Enhances Boost quasi Z-Source inverter (EB-qZSI). Similar to the EB-QZSI, because of the presence of a series inductor with input voltage source, the inrush current at start-up is limited in the proposed topology. Also, the low voltage stress on the capacitors and the low current ripple of the inductors and the input source are other advantages. Due to the lower number of diodes in the proposed inverter, the efficiency is higher compared to the EB-qZSI inverter. The performance of the proposed topology is confirmed with MATLAB/SIMULINK software. The results of simulation and experimental validate the theoretical analysis of the proposed topology. The experimental results validate the simulation results and there is a good agreement between the simulation results and the experimental results.
Industrial Electronics
Alireza Karbalaei; Mohammad Mardaneh
Abstract
This paper proposes a topology of switched-inductor/capacitor quasi z-source inverter (SIC-qZSI), which based on the classic qZSI. This topology is symmetric and has a high boost factor in the low duty cycle and high modulation index. Also, the low voltage stress on the capacitors and the low current ...
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This paper proposes a topology of switched-inductor/capacitor quasi z-source inverter (SIC-qZSI), which based on the classic qZSI. This topology is symmetric and has a high boost factor in the low duty cycle and high modulation index. Also, the low voltage stress on the capacitors and the low current ripple of the inductors and the input source are other advantages. In addition, the current of all inductors and the input current are equal, and the voltage across all the inductors, as well as the voltage across all diodes, are equal. This inverter has continuous current in the input source, and has common ground between the input voltage source and the inverter bridge. In order to express the features of the proposed inverter, it is compared experimentally in similar conditions relative to the Enhances Boost quasi Z-Source inverter (EB-qZSI). The performance of the proposed topology is confirmed with MATLAB/SIMULINK software and the simulation results and obtained relations are accredit by using a prototype of the proposed inverter.
Industrial Electronics
Mahmoodreza Eskandarpour Azizkandi; Farzad Sedaghati; Hossein Shayeghi
Abstract
A new non-isolated, coupled-inductor, single-switch boost DC-DC converter for photovoltaic (PV) power application is introduced in this paper. A coupled inductor and voltage multiplier cells is used in the presented converter to obtain a high voltage conversion ratio. Also, a passive clamp circuit is ...
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A new non-isolated, coupled-inductor, single-switch boost DC-DC converter for photovoltaic (PV) power application is introduced in this paper. A coupled inductor and voltage multiplier cells is used in the presented converter to obtain a high voltage conversion ratio. Also, a passive clamp circuit is applied in the converter structure to reduce voltage stress of the power switch. This leads to using a power switch with lower on-state resistance in the converter which decreases the conduction loss. In addition, zero current switching (ZCS) condition for the power switch is achieved due to the use of the clamp circuit. Several advantages such as low operating duty cycle, high voltage conversion ratio, reduced voltage stress of semiconductors, low turn ratio for the coupled inductor, leakage inductance reverse recovery and high efficiency operation make the presented converter suitable for renewable energy applications. The steady state operation of the suggested structure in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) is expressed and analyzed. Then, the presented topology is compared with several similar high gain topologies to prove its advantages. Finally, experimental measurement results of a laboratory prototype of the proposed DC-DC converter with about 213W output power and 435V output voltage at 50 kHz switching frequency are presented to corroborate its feasibility and performance.
Industrial Electronics
Mohammad Monfard; Mohammad Babaei; Saeed Sharifi
Abstract
This paper presents a wide range gain buck-boost type PFC rectifier based on the conventional buck-boost DC-DC converter. This novel rectifier is fed by a buck-type Z-source network at the DC side with the help of an inductor smoothing the AC side input current. The proposed PFC rectifier offers better ...
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This paper presents a wide range gain buck-boost type PFC rectifier based on the conventional buck-boost DC-DC converter. This novel rectifier is fed by a buck-type Z-source network at the DC side with the help of an inductor smoothing the AC side input current. The proposed PFC rectifier offers better input and output waveform qualities compared to the conventional buck-boost PFC rectifier. Maintaining near to unity power factor (PF) and low total harmonic distortion (THD) in a wide range of load variations and also the simple single-loop control are the main features of the proposed PFC rectifier. Furthermore, the switching frequency of the proposed rectifier can be chosen very higher than the competitors, since it successfully lets incredibly increase the duty cycle for a same voltage gain compared to the traditional solutions. This leads to reduced size of passive components and volume of the rectifier. A 250 W prototype circuit is designed and simulated considering most practical issues to evaluate the performance of the proposed PFC in both buck and boost modes. The results are compared with some of the well-known conventional PFC rectifiers that confirm the superior performance of the proposed topology.
Industrial Electronics
asghar taheri; Ahad Rasulkhani
Abstract
Multilevel inverters as a main component of electrical systems have been discussed over the past decade. Todays, improving their performance is one of the important challenges that has led to many studies in their topology and control system. In this paper, a new topology of symmetrical multi-level inverters ...
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Multilevel inverters as a main component of electrical systems have been discussed over the past decade. Todays, improving their performance is one of the important challenges that has led to many studies in their topology and control system. In this paper, a new topology of symmetrical multi-level inverters is provided that is able to feed inductive loads. The proposed topology has fewer power elements such as IGBTs, driver circuits, diodes and dc voltages. To increase the number of output voltage levels, several basic topology can be in cascaded structure. Comparison of proposed inverter topology with some conventional symmetrical topologies shows that the proposed topology has better efficiency in aspects of the number of IGBTs, losses and blocked voltage blocked in the switches. The performance and efficiency of the proposed inverter are verified by simulation and experimental results of a 9-level symmetrical inverter.The quality of a multi-level inverter specifies by its number of output levels.
Industrial Electronics
mohammad hosein ershadi; shahrokh shojaeian; reza keramat
Abstract
In this paper, the Brain Emotional Learning Based Intelligent Controller (BELBIC) and fuzzy controller were used to control output voltage of the full bridge DC-DC converter. The converter is presented by its state space averaged model assuming that it operates in the continuous conduction mode (CCM). ...
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In this paper, the Brain Emotional Learning Based Intelligent Controller (BELBIC) and fuzzy controller were used to control output voltage of the full bridge DC-DC converter. The converter is presented by its state space averaged model assuming that it operates in the continuous conduction mode (CCM). A comparison was also made between the results. The effectiveness of control approaches are demonstrated by the uncertainty of system parameters and acceptable load variations. The performance of the BEBLIC and fuzzy controller in controlling the output voltage of the full bridge DC-DC converter was satisfactory. Since these controllers are not designed to reduce error to zero, it is not possible to claim that the error rate is precisely zero. Compared to the fuzzy controller, the BELBIC shows negligible overshoots and fluctuations. Both controllers reach stabilization almost at once. It is, therefore, concluded that the BELBIC acts better than the fuzzy controller. Considering the uncertainty of system parameters (including inductance, capacitance, and input voltage and acceptable variations of load), BELBIC acts better than the fuzzy controller.
Industrial Electronics
Farzad Sedaghati; Seyed Hadi Latifi Majareh; Hadi Dolati
Abstract
This paper presents a single-phase topology for multilevel inverters with minimum number of switching devices. The proposed topology significantly reduces the number of DC voltage sources, switches, and power diodes as the number of output voltage levels increases. The proposed multilevel inverter is ...
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This paper presents a single-phase topology for multilevel inverters with minimum number of switching devices. The proposed topology significantly reduces the number of DC voltage sources, switches, and power diodes as the number of output voltage levels increases. The proposed multilevel inverter is constructed using series-connection of multilevel strings. Suggested multilevel string is composed of multiple basic switching units. The proposed multilevel inverter has extendable configuration that increases the number of output voltage levels more and more by adding more stages. The proposed multilevel inverter would be implemented in both symmetric and asymmetric configurations. Two different algorithms are introduced for determination of magnitude of DC voltage sources to reach the maximum number of output voltage levels with minimum number of semiconductor devices. Important characteristics of both symmetric and asymmetric configurations are extracted and compared with similar multilevel inverter topologies. Finally, a prototype of the proposed multilevel inverter is simulated and implemented experimentally to verify operation of the proposed multilevel inverter.
Industrial Electronics
Mahdi Radmehr; Mohammad Mojibi
Abstract
Reliability consideration is always important among the manufacturers of power modules and converters. Before using of power electronic converters into the related application, it is necessary to predict its reliability over time. In the meanwhile, the power loss and heat generated within the power semiconductors ...
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Reliability consideration is always important among the manufacturers of power modules and converters. Before using of power electronic converters into the related application, it is necessary to predict its reliability over time. In the meanwhile, the power loss and heat generated within the power semiconductors play a key role in the lifespan of the whole system. In this paper, a method for assessing the reliability of a step-down DC-DC converter is employed based on the thermal modeling of power semiconductors. As is evident from the used reliability approach, the junction temperature of power semiconductors – diodes and insulated-gate bipolar transistors (IGBTs) – is the most influential factor on the lifetime of power converters. Therefore, the simultaneous influence of switching frequency and duty cycle is analyzed at the same time as a factor for evaluating reliability. A cut-off of 150°C is considered for the maximum allowable junction temperature for the examined IGBT power module. The results show that a failure can be expected after 46,000 hours of operation of the considered power converter. Additionally, 3D curves are presented to illustrate the influence of duty cycle and switching frequency on the reliability of circuit’s components and the overall system. The obtained results confirmed that an increase in switching frequency from 1 kHz to 10 kHz can decrease the circuit’s lifetime almost 22%.
Industrial Electronics
asghar taheri; Nader Asgari
Abstract
In this paper, a sliding mode control of LLC resonant dc-dc converter in low voltage and high current application is presented. The proposed controller operates at two fixed switching frequencies to the battery charger of electric vehicles. In resonant converter, because of the soft switching process, ...
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In this paper, a sliding mode control of LLC resonant dc-dc converter in low voltage and high current application is presented. The proposed controller operates at two fixed switching frequencies to the battery charger of electric vehicles. In resonant converter, because of the soft switching process, switching loss is negligible and converters can be designed at high frequencies to reduce the size, weight and price. To analyze this convertor the harmonic approximation method with state space equation is used. Taking advantage of the approximations used in order to avoid uncertainty, sliding mode control method is used. The mentioned convertor with the proposed controlled is exploited within three switching frequency bands that are lower than resonant frequency, resonant frequency and above resonant frequency. Due to the robustness of the sliding mode control, the output voltage regulation occurs with minimum distortion under a wide variation of input voltage, output voltage and output current. As a result, the battery life increases. In order to verify the results and effectiveness of the proposed converters, the prototype of LLC resonant converters Simulation and experimental results for the input voltage 300-420 V dc, output voltage 36-72 V dc and current output (0-11 A) is presented. The prototype achieves a peak efficiency value of 96%.
