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Power Electronics, IEEE Transactions on

Issue 4 • Date April 2011

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Displaying Results 1 - 25 of 35
  • [Front cover]

    Publication Year: 2011 , Page(s): C1
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  • IEEE Transactions on Power Electronics publication information

    Publication Year: 2011 , Page(s): C2
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  • Table of contents

    Publication Year: 2011 , Page(s): 999 - 1000
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  • A Real Maximum Power Point Tracking Method for Mismatching Compensation in PV Array Under Partially Shaded Conditions

    Publication Year: 2011 , Page(s): 1001 - 1009
    Cited by:  Papers (80)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1761 KB) |  | HTML iconHTML  

    Conventional popular maximum power point tracking (MPPT) methods are effective under uniform solar irradiance. However, under solar irradiance mismatching conditions [partially shaded conditions (PSCs)], these MPPTs can fail for real MPPT (RMPPT), because multiple local maxima can be exhibited on the power-voltage characteristic curve. Although some researchers have worked on RMPPT under partial shading conditions, the methods have some drawbacks in terms of complexity and requirements for additional circuits, etc. In this paper, a novel MPPT method capable of RMPPT under PSCs is proposed. The performance of the proposed MPPT method is analyzed according to the RMPP position and is verified by simulation and experimental results. View full abstract»

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  • High-Performance Adaptive Perturb and Observe MPPT Technique for Photovoltaic-Based Microgrids

    Publication Year: 2011 , Page(s): 1010 - 1021
    Cited by:  Papers (96)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2559 KB) |  | HTML iconHTML  

    Solar photovoltaic (PV) energy has witnessed double-digit growth in the past decade. The penetration of PV systems as distributed generators in low-voltage grids has also seen significant attention. In addition, the need for higher overall grid efficiency and reliability has boosted the interest in the microgrid concept. High-efficiency PV-based microgrids require maximum power point tracking (MPPT) controllers to maximize the harvested energy due to the nonlinearity in PV module characteristics. Perturb and observe (P&O) techniques, although thoroughly investigated in previous research, still suffer from several disadvantages, such as sustained oscillation around the MPP, fast tracking versus oscillation tradeoffs, and user predefined constants. In this paper, a modified P&O MPPT technique, applicable for PV systems, is presented. The proposed technique achieves: first, adaptive tracking; second, no steady-state oscillations around the MPP; and lastly, no need for predefined system-dependent constants, hence provides a generic design core. A design example is presented by experimental implementation of the proposed technique. Practical results for the implemented setup at different irradiance levels are illustrated to validate the proposed technique. View full abstract»

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  • Fuzzy-Logic-Control Approach of a Modified Hill-Climbing Method for Maximum Power Point in Microgrid Standalone Photovoltaic System

    Publication Year: 2011 , Page(s): 1022 - 1030
    Cited by:  Papers (59)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1318 KB) |  | HTML iconHTML  

    A new fuzzy-logic controller for maximum power point tracking of photovoltaic (PV) systems is proposed. PV modeling is discussed. Conventional hill-climbing maximum power-point tracker structures and features are investigated. The new controller improves the hill-climbing search method by fuzzifying the rules of such techniques and eliminates their drawbacks. Fuzzy-logic-based hill climbing offers fast and accurate converging to the maximum operating point during steady-state and varying weather conditions compared to conventional hill climbing. Simulation and experimentation results are provided to demonstrate the validity of the proposed fuzzy-logic-based controller. View full abstract»

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  • A New Approach to Achieve Maximum Power Point Tracking for PV System With a Variable Inductor

    Publication Year: 2011 , Page(s): 1031 - 1037
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1006 KB) |  | HTML iconHTML  

    Maximum power transfer in solar microgrid applications is achieved by impedance matching with a dc-dc converter with maximum power point tracking by the incremental conductance method. Regulation and dynamic control is achieved by operating with continuous conduction. It can be shown that under stable operation, the required output inductor has an inductance versus current characteristic, whereby the inductance falls off with increasing current, corresponding to increasing incident solar radiation. This paper describes how a variable inductor whereby the inductor core progressively saturates with increasing current meets this requirement and has the advantage of reducing the overall size of the inductor by up to 75% and increases the operating range of the tracker to recover solar energy at low solar levels. View full abstract»

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  • New Approach for MPPT Control of Photovoltaic System With Mutative-Scale Dual-Carrier Chaotic Search

    Publication Year: 2011 , Page(s): 1038 - 1048
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1295 KB) |  | HTML iconHTML  

    As the output power of photovoltaic (PV) array changes with the change of external environment and load, the maximum power point tracking (MPPT) technology is needed to bring the efficiency of PV device into full play. In this paper, the chaos search theory is first applied on the MPPT technology of PV system; the chaos search algorithm based on dual carrier increases the adequacy of chaos search and overcomes the blindness of traditional chaos search, thus improves the search efficiency and solves the problem of multiple MPP under partially shadowing conditions. Comparative tests show that the proposed method can track the step response quickly and accurately; at the same time get better optimization result. Simulation and experimental results showed the effectiveness and good performance of the proposed method. View full abstract»

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  • An Islanding Detection Method for a Grid-Connected System Based on the Goertzel Algorithm

    Publication Year: 2011 , Page(s): 1049 - 1055
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1409 KB) |  | HTML iconHTML  

    Islanding refers to a condition of a distributed generator (DG) in that it continues to power a location even though power from the grid is no longer present. This condition can be dangerous to grid workers who may not realize that the load is still powered even though there is no power from the grid. Adverse effects of islanding are low power quality, grid-protection interference, equipment damage, and personnel safety hazards. For these reasons, DG systems must detect an islanding condition and immediately stop producing power; this is referred to as anti-islanding. Islanding detection methods can be categorized into two major approaches: the passive and active methods. The passive methods are based on measurement of the natural effects of islanding. The active methods use intentional transients or harmonic effects. When the power generated by the DG matches the load power consumption, passive methods fail due to the small natural effects of islanding. Therefore, the passive methods have a nondetection zone (NDZ). The active methods can reduce the NDZ size. However, these methods reduce the grid power quality. In this paper, a novel anti-islanding method (AIM) is proposed. A single-phase DG using the proposed AIM injects the output current with a little harmonic current into the grid and monitors the harmonic components of the voltage at the point of common coupling using the Goertzel algorithm. The Goertzel algorithm is a kind of discrete Fourier transform. It extracts the magnitude and phase of the desired frequency from the input signal, with a minimum computation. The proposed islanding detection algorithm resolves the NDZ but also the bad effects on the grid power quality due to injecting harmonic components qualified by the interconnection standard. The proposed islanding detection method was verified using PSIM (see www.powersimtech.com) simulations and experimental results. View full abstract»

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  • An Active Anti-Islanding Method Based on Phase-PLL Perturbation

    Publication Year: 2011 , Page(s): 1056 - 1066
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1492 KB) |  | HTML iconHTML  

    This paper presents a new active anti-islanding detection method for distributed power generation systems. This method is based on introducing a disturbance at the inverter output and observing the behavior of the voltage at the point of common coupling (PCC), which depends on the impedance connected to the PCC in an islanding situation. The islanding detection is based on the Goertzel algorithm. View full abstract»

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  • Analysis and Digital Implementation of Cascaded Delayed-Signal-Cancellation PLL

    Publication Year: 2011 , Page(s): 1067 - 1080
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1496 KB) |  | HTML iconHTML  

    Phase-locked loop (PLL) is usually required to detect grid phase angle in grid-tied converters. Conventional PLL schemes have to compromise between steady-state accuracy and transient dynamics when grid voltage is polluted by unbalance and harmonics. To overcome this challenge, a generalized delayed-signal-cancellation (DSC) operator is proposed recently to form cascaded DSC (CDSC) operator to eliminate arbitrary harmonics. With the CDSC operator, the conditioned voltage can be used in PLL loop with very high bandwidth for fast tracking. However, for digital implementation, the CDSC operator may subject to delay-time error, which subsequently leads to residual distortions in the conditioned voltage. In this paper, a thorough analysis of the CDSC operator in both synchronous and stationary reference frames is first conducted. The discretization error during digital implementation due to nonideal system sampling frequency and/or grid-frequency variation is quantified with the proposed concept of relative harmonic gain error. An effective improvement method is then developed that is based on linear interpolation and is effective for all delay-based PLL schemes. Finally, experimental results are obtained to verify the harmonic elimination ability of CDSC in various scenarios and the effectiveness of the interpolation-based digital implementation scheme. View full abstract»

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  • A Novel Fast-Tracking D-Estimation Method for Single-Phase Signals

    Publication Year: 2011 , Page(s): 1081 - 1088
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (767 KB) |  | HTML iconHTML  

    The phase, frequency, and amplitude of single-phase voltages are the most important and basic information required for single-phase microgrid connected applications. This paper proposes a new “D-estimation method” for instantly estimating the phase, frequency, and amplitude of frequency-varying single-phase signals in such applications. The D-estimation method has the following attractive features: 1) it is a new filtering method using the D-filters; 2) it involves the use of only filters and can be easily designed; 3) it is inherently stable and robust in hostile envelopments caused by a frequency variation, a phase jump, amplitude sag/swell, harmonic distortion, and/or contaminated noise; 4) even in the hostile envelopments, good instant estimates of the phase, frequency, and amplitude can be obtained; 5) it is simple, but can exhibit fast-tracking performance comparable to the “robust PLL method.” This paper presents the D-estimation method together with the design rules in detail; the usefulness of the method is verified by performing extensive numerical experiments. View full abstract»

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  • Robust frequency-estimation method for distorted and imbalanced three-phase systems using discrete filters

    Publication Year: 2011 , Page(s): 1089 - 1101
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1652 KB) |  | HTML iconHTML  

    The continuous monitoring of voltage characteristics in electric power systems, such as in microgrids, is required for power quality assessment, grid control, and protection purposes. Due to the presence of disturbances in the grid voltage, such as harmonics, imbalances, noise, and offsets introduced by the instrumentation, among others, the frequency-estimation process has to be robust against all these disturbances to obtain an accurate estimation of the frequency value. This paper presents a fast and accurate method to estimate the fundamental frequency of an electric power system. The estimation method works properly in balanced and imbalanced three-phase systems, and even in single-phase systems. The proposed solution is based on an algebraic method, which is able to calculate the frequency of a pure sinusoidal signal using three samples. A filtering stage is used to increase the robustness of the algorithm against disturbances in a wide frequency range. Simulation and experimental results show the good performance of the method for single- and three-phase systems with a high level of harmonic distortion, even in the presence of amplitude, phase, and frequency changes. View full abstract»

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  • An SVPWM-Based Switching Pattern for Stand-Alone and Grid-Connected Three-Phase Single-Stage Boost Inverters

    Publication Year: 2011 , Page(s): 1102 - 1111
    Cited by:  Papers (30)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1476 KB) |  | HTML iconHTML  

    In many modern energy conversion systems, a dc voltage, which is provided from a sustainable energy source or energy storage device, must be boosted and converted to an ac voltage with a fixed amplitude and frequency. In this paper, a switching pattern based on the concept of the conventional space-vector pulsewidth-modulated (SVPWM) technique is developed for single-stage, three-phase boost-inverters using the topology of current-source inverters. The six main switching states, and two zeros, with three switches conducting at any given instant in conventional SVPWM techniques are modified herein into three-charging states and six discharging states with only two switches conducting at any given instant. The charging states are necessary in order to boost the dc input voltage. The developed switching pattern was experimentally verified through a laboratory-scaled three-phase 500-W boost inverter and the results are presented in this paper. View full abstract»

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  • Experimental Verification of the Active Front-End Converters Dynamic Model and Control Designs

    Publication Year: 2011 , Page(s): 1112 - 1118
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1399 KB) |  | HTML iconHTML  

    This paper presents a dynamic model of the active front-end (AFE) converter in the synchronous reference frame under balance input voltage condition. Transfer functions of the closed-loop control based on this dynamic model are verified experimentally in the frequency domain. Bode plots of these transfer functions are given to validate this synchronous frame-based dynamic model. Based on these results, this paper presents the control designs of the AFE converter to enhance the disturbance rejection capability and robustness. The control designs are then verified experimentally in the frequency domain. The frequency response of the AFE converter system is measured by an Agilent 35670A dynamic signal analyzer to validate the performance of the AFE converter system. View full abstract»

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  • A multicarrier pulse width modulator for the auxiliary converter and the diode rectifier

    Publication Year: 2011 , Page(s): 1119 - 1126
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1500 KB) |  | HTML iconHTML  

    The auxiliary converter (AXC) has been presented as a cost-effective solution to retrofit the conventional diode rectifier into a unity power factor and regeneration-enabled front end. The transistor-based AXC operates as an active filter when the load system consumes power. When the load system regenerates, the AXC can transfer the energy back to the ac grid. However, the pulse width modulation (PWM) switching of the AXC often causes circulating current between the AXC and the diode rectifier. The zero vectors of each PWM cycle induce zero sequence current, which results in increased operational losses and electrical noise. This study analyzes the circulating current and investigates the use of multicarrier PWM for its suppression. This multicarrier PWM can synthesize the desired output voltage without using zero vectors for the active filtering and regeneration operations of the AXC, and thus significantly suppress the circulating current and common mode voltage. Test results are presented to validate the effectiveness of the proposed multicarrier PWM in the AXC circuit system. View full abstract»

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  • A Novel High Step-Up DC–DC Converter for a Microgrid System

    Publication Year: 2011 , Page(s): 1127 - 1136
    Cited by:  Papers (44)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1557 KB) |  | HTML iconHTML  

    A novel high step-up dc-dc converter for a distributed generation system is proposed in this paper. The concept is composed of two capacitors, two diodes, and one coupled inductor. Two capacitors are charged in parallel, and are discharged in series by the coupled inductor. Thus, high step-up voltage gain can be achieved with an appropriate duty ratio. The voltage stresses on the main switch and output diode are reduced by a passive clamp circuit. Therefore, low resistance R for the main switch can be adopted to reduce conduction loss. In addition, the reverse-recovery problem of the diode is alleviated, and thus, the efficiency can be further improved. The operating principle and steady-state analyses of the voltage gain are also discussed in detail. Finally, a 24-V input voltage, 400-V output voltage, and 400-W output power prototype circuit of the proposed converter are implemented in the laboratory to verify the performance. View full abstract»

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  • Interleaved Soft-Switching Boost Converter for Photovoltaic Power-Generation System

    Publication Year: 2011 , Page(s): 1137 - 1145
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1829 KB) |  | HTML iconHTML  

    In this paper, a interleaved soft switching boost converter (ISSBC) for a photovoltaic (PV) power-generation system is proposed. The topology used raises the efficiency for the dc/dc converter of the PV power conditioning system (PVPCS), and it minimizes switching losses by adopting a resonant soft-switching method. A detailed mode analysis of the proposed topology is presented. The feasibility of the proposed topology is experimentally verified for a 1.2-kW prototype. The experimental results imply that 97.28% efficiency is achieved under the full-load condition. Consequently, it is confirmed that the overall efficiency is increased by about 1.5% compared with the conventional hard switching interleaved boost converter. View full abstract»

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  • A Cascaded High Step-Up DC–DC Converter With Single Switch for Microsource Applications

    Publication Year: 2011 , Page(s): 1146 - 1153
    Cited by:  Papers (49)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (884 KB) |  | HTML iconHTML  

    This paper proposes a new high step-up dc-dc converter designed especially for regulating the dc interface between various microsources and a dc-ac inverter to electricity grid. The figuration of the proposed converter is a quadratic boost converter with the coupled inductor in the second boost converter. The converter achieves high step-up voltage gain with appropriate duty ratio and low voltage stress on the power switch. Additionally, the energy stored in the leakage inductor of the coupled inductor can be recycled to the output capacitor. The operating principles and steady-state analyses of continuous-conduction mode and boundary-conduction mode are discussed in detail. To verify the performance of the proposed converter, a 280-W prototype sample is implemented with an input voltage range of 20-40 V and an output voltage of up to 400 V. The upmost efficiency of 93.3% is reached with high-line input; on the other hand, the full-load efficiency remains at 89.3% during low-line input. View full abstract»

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  • Research on voltage and power balance control for cascaded modular solid-state transformer

    Publication Year: 2011 , Page(s): 1154 - 1166
    Cited by:  Papers (43)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2172 KB) |  | HTML iconHTML  

    The solid-state transformer (SST) is one of the key elements in power electronic-based microgrid systems. The single-phase SST consists of a modular multilevel ac-dc rectifier, a modular dual active bridge (DAB) dc-dc converter with high-frequency transformers, and a dc-ac inverter stage. However, due to dc bus voltage and power unbalancing in each module, the modular SST often presents instability problems making its design difficult and causing unpredictable behavior. Moreover, the unbalanced dc-link voltages increase the stress of the semiconductor devices, and also cause high harmonic distortions of grid current, therefore, necessitating the use of a bigger ac filter. This paper presents a novel single-phase d-q vector-based common-duty-ratio control method for the multilevel rectifier, and a voltage feedforward and feedback based controller for the modular DAB converter. With the proposed control methods, the dc-link voltage and power in each module can be balanced. In addition, the low-distortion grid current, unity power factor, and bidirectional power flow can be achieved. Simulation and experimental results are presented to validate the proposed control methods. View full abstract»

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  • Stochastic Polynomial-Chaos-Based Average Modeling of Power Electronic Systems

    Publication Year: 2011 , Page(s): 1167 - 1171
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (266 KB) |  | HTML iconHTML  

    With the introduction of variable-frequency generators in next-generation more-electric aircraft, both voltage and frequency are to reveal significant tolerance levels. In this study, a method based on the combination of polynomial chaos and nodal analysis is developed to identify and quantify the impact of such tolerance in ac/dc diode rectifiers and dc/dc switch-mode converters. The resulting stochastic average models track the transients of the tolerance limits and related information in the time domain both accurately and efficiently. The relative merits of the method are substantiated through a comparative analysis with the Monte Carlo and root-sum-square methods. View full abstract»

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  • Three-Phase (LC)(L)-Type Series-Resonant Converter With Capacitive Output Filter

    Publication Year: 2011 , Page(s): 1172 - 1183
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1877 KB) |  | HTML iconHTML  

    This paper presents a three-phase (LC)(L)-type dc-dc series-resonant converter with capacitive output filter. Operation of the converter has been presented using the operating waveforms and equivalent-circuit diagrams during different intervals. An approximate analysis is used, and design procedure is presented with a design example. Intusoft simulation results for the designed converter are given for input voltage and load variations. Experimental results obtained with a 300-W converter are presented. Major advantages of this converter are the leakage and magnetizing inductances of the high-frequency transformer that are used as a part of resonant circuit, and the output-rectifier voltage is clamped to the output voltage. Also, the converter operates in soft switching for the inverter switches with a narrow frequency control range and the tank current decreases with the load current. View full abstract»

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  • An Improved Deadbeat Scheme With Fuzzy Controller for the Grid-side Three-Phase PWM Boost Rectifier

    Publication Year: 2011 , Page(s): 1184 - 1191
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1127 KB) |  | HTML iconHTML  

    The model of deadbeat current controller for the grid-side three-phase boost pulsewidth modulation (PWM) rectifier was presented in this paper. Based on this model, the inherent relationship among predictive algorithms, current overshoot, and phase delay was obtained by analyzing three widely used predictive algorithms in different kinds of reference variations. Then, a novel scheme to select the prediction parameter in deadbeat controller was proposed to improve the performance. By using the fuzzy control strategy, a proper predictive parameter was chosen, which not only limits the maximum current overshoot, but also adjusts the phase delay. Both the transient and the steady characteristic of the proposed controller were validated by the simulation results. Finally, an experimental prototype of a three-phase voltage-source PWM rectifier controlled by a TMS320F2812DSP was built and tested. The experimental results verified the validity of the proposed control approach. View full abstract»

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  • EMI Filter Design for a 1 MHz, 10 kW Three-Phase/Level PWM Rectifier

    Publication Year: 2011 , Page(s): 1192 - 1204
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1781 KB) |  | HTML iconHTML  

    The attenuation characteristics of electromagnetic interference (EMI) filters in practice often differ from theoretical predictions and minor changes can result in a significant improvement in performance. The performance of the differential-mode (DM) filter stage can usually be well predicted, but the common mode (CM) behavior is more difficult to handle. This is especially true for three-phase pulsewidth modulation (PWM) rectifier systems, which inherently show a large high-frequency CM voltage at the rectifier output. Possible CM noise current paths of a three-phase/level PWM rectifier are analyzed in this paper where parasitic capacitances to the heat sink and to earth are considered. In addition, a concept to significantly reduce CM emissions is discussed in detail. Based on the proposed models, an EMI filter design for a system with 1 MHz switching frequency is shown. Experimental verification of the designed EMI filter is presented by impedance and conducted emission (CE) measurements taken from a 10 kW prototype. Several practical aspects of filter implementation such as component arrangement, shielding layers, magnetic coupling, etc., are discussed and verified by measurements. View full abstract»

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  • A MASH-Controlled Multilevel Power Converter for High-Efficiency RF Transmitters

    Publication Year: 2011 , Page(s): 1205 - 1214
    Cited by:  Papers (7)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1558 KB) |  | HTML iconHTML  

    Envelope tracking (ET) is one of the most promising transmitter architectures proposed to increase the efficiency of modern wireless communication system. An ET transmitter consists of a linear RF power amplifier and a high-efficiency envelope amplifier, which is always a switched-mode power converter. The envelope amplifier provides a varying drain (collector) bias voltage, which tracks the envelope of the RF input signal, for the RF power amplifier. Thus, the RF power amplifier keeps working in high-efficiency region of most of the time. Therefore, the overall efficiency of the transmitter is increased. This paper proposes a multistage noise-shaping-technique-controlled multilevel power converter to perform as the envelope amplifier in an ET transmitter. Experimental results show that the proposed power converter can reproduce any envelope signals with the maximum spectrum component of 300 kHz and give maximum instantaneous power of 20 W. Compared with pulsewidth modulation, the noise-shaping technique can shape the ripple into noise and the noise will be attenuated by the low-pass filter, which results a better performance, while maintaining high efficiency as well. View full abstract»

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Aims & Scope

IEEE Transactions on Power Electronics covers fundamental technologies used in the control and conversion of electric power.

Full Aims & Scope