scispace - formally typeset
Search or ask a question

Showing papers on "Power factor published in 2014"


Journal ArticleDOI
TL;DR: Electrical and practical designs of the inverter, power lines, pickup, rectifier, and regulator as well as an optimized core structure design for a large air gap for electromotive force shielding for the electric vehicle are described.
Abstract: In this paper, the design and implementation of a wireless power transfer system for moving electric vehicles along with an example of an online electric vehicle system are presented. Electric vehicles are charged on roadway by wireless power transfer technology. Electrical and practical designs of the inverter, power lines, pickup, rectifier, and regulator as well as an optimized core structure design for a large air gap are described. Also, electromotive force shielding for the electric vehicle is suggested. The overall system was implemented and tested. The experimental results showed that 100-kW power with 80% power transfer efficiency under 26-cm air gap was acquired.

725 citations


Journal ArticleDOI
TL;DR: In this article, an impedance-based analytical approach is employed and expanded to a meshed and balanced three-phase network which is dominated by multiple current and voltage-controlled inverters with LCL-and LC-filters.
Abstract: This paper addresses the harmonic stability caused by the interactions among the wideband control of power converters and passive components in an ac power-electronics-based power system. The impedance-based analytical approach is employed and expanded to a meshed and balanced three-phase network which is dominated by multiple current- and voltage-controlled inverters with LCL- and LC-filters. A method of deriving the impedance ratios for the different inverters is proposed by means of the nodal admittance matrix. Thus, the contribution of each inverter to the harmonic stability of the power system can be readily predicted through Nyquist diagrams. Time-domain simulations and experimental tests on a three-inverter-based power system are presented. The results validate the effectiveness of the theoretical approach.

616 citations


Journal ArticleDOI
TL;DR: In this article, the relationship among compensation parameters, circuit efficiency, voltage transfer function, and conduction angle of the input current relative to the input voltage are studied, and a design and optimization method is proposed to achieve a better overall efficiency as well as good output voltage controllability.
Abstract: Inductive power transfer (IPT) is an emerging technology that may create new possibilities for wireless power charging and transfer applications. However, the rather complex control method and low efficiency remain the key obstructing factors for general deployment. In a regularly compensated IPT circuit, high efficiency and controllability of the voltage transfer function are always conflicting requirements under varying load conditions. In this paper, the relationships among compensation parameters, circuit efficiency, voltage transfer function, and conduction angle of the input current relative to the input voltage are studied. A design and optimization method is proposed to achieve a better overall efficiency as well as good output voltage controllability. An IPT system design procedure is illustrated with design curves to achieve a desirable voltage transfer ratio, optimizing between efficiency enhancement and current rating of the switches. The analysis is supported with experimental results.

404 citations


Journal ArticleDOI
TL;DR: The concept of “commutation inductance(s)” is shown to be an essential element in achieving full-operating-range ZVS, taking into account the amount of charge that is required to charge the nonlinear parasitic output capacitances of the switches during commutation.
Abstract: A comprehensive procedure for the derivation of optimal, full-operating-range zero voltage switching (ZVS) modulation schemes for single-phase, single-stage, bidirectional and isolated dual active bridge (DAB) ac-dc converters is presented. The converter topology consists of a DAB dc-dc converter, receiving a rectified ac line voltage via a synchronous rectifier. The DAB comprises primary and secondary side full bridges, linked by a high-frequency isolation transformer and a series inductor. ZVS modulation schemes previously proposed in the literature are either based on current-based or energy-based ZVS analyses. The procedure outlined in this paper for the calculation of optimal DAB modulation schemes (i.e., combined phase-shift, duty-cycle, and switching frequency modulation) relies on a novel, more accurate, current-dependent charge-based ZVS analysis, taking into account the amount of charge that is required to charge the nonlinear parasitic output capacitances of the switches during commutation. Thereby, the concept of “commutation inductance(s)” is shown to be an essential element in achieving full-operating-range ZVS. The proposed methods are applied to a 3.7 kW, bidirectional, and unity power factor electric vehicle battery charger which interfaces a 400 V dc-bus with the 230 Vac, 50-Hz utility grid. Experimental results obtained from a high-power-density, high-efficiency converter prototype are given to validate the theoretical analysis and practical feasibility of the proposed strategy.

356 citations


Journal ArticleDOI
TL;DR: In this paper, a virtual synchronous machine (VSM) is used to support dynamic frequency control in a diesel-hybrid autonomous power system, where self-tuning algorithms are used to continuously search for optimal parameters during the operation of the VSM in order to minimize the amplitude and rate of change of the frequency variations and the power flow through the ESS.
Abstract: This paper investigates the use of a virtual synchronous machine (VSM) to support dynamic frequency control in a diesel-hybrid autonomous power system. The proposed VSM entails controlling the grid-interface converter of an energy storage system (ESS) to emulate the inertial response and the damping power of a synchronous generator. In addition, self-tuning algorithms are used to continuously search for optimal parameters during the operation of the VSM in order to minimize the amplitude and rate of change of the frequency variations and the power flow through the ESS. The performances of the proposed self-tuning (ST)-VSM and the constant parameters (CP)-VSM were evaluated by comparing their inertial responses and their damping powers for different scenarios of load variations. For the simulated cases, the ST-VSM achieved a similar performance to that of the CP-VSM, while reducing the power flow through the ESS in up to 58%. Moreover, in all the simulated scenarios, the ST-VSM was found to be more efficient than the CP-VSM in attenuating frequency variations, i.e., it used less energy per Hertz reduced.

314 citations


Journal ArticleDOI
TL;DR: In this paper, an analysis of the energy-storage requirements of modular multilevel converters is presented, which relates the power transfer capability to the stored energy in the converter and the findings are validated by both simulations and experimental results.
Abstract: The modular multilevel converter is a promising topology for high-voltage and high-power applications. By using submodules equipped with dc-capacitors excellent output voltage waveforms can be obtained at low switching frequencies. The rated energy storage of the submodule capacitors is a driving factor of the size, cost, and weight of the submodules. Although the modular multilevel converter has been thoroughly investigated in the literature, a more detailed analysis of the energy-storage requirements will provide an important contribution for dimensioning and analysis of modular multilevel converters. Such an analysis is presented in this paper. The analysis relates the power transfer capability to the stored energy in the converter and the findings are validated by both simulations and experimental results. The required size of the submodule capacitors in a 4.5 MW grid-connected converter is first calculated and the calculated operating range is then compared with simulation results. The experimental results show that if the average capacitor voltage is allowed to increase 10% above the nominal value an energy storage to power transfer ratio of 21 J/kW can be achieved. It is concluded that the presented theory can relate the power transfer capability to the energy storage in the converter and is thus a valuable tool in the design and analysis of modular multilevel converters.

312 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a dc-DC-DC converter to realize power quality independence from the utility mains by merging renewable energy sources (RESs) into dedicated dc distribution architectures through corresponding dc-dc converters.
Abstract: Current trends indicate that worldwide electricity distribution networks are experiencing a transformation toward direct current (dc) at both the generation and consumption level. This tendency is powered by the outburst of various electronic loads and, at the same time, the struggle to meet the lofty goals for the sharing of renewable energy sources (RESs) in satisfying total demand. RESs operate either natively at dc or have a dc link in the heart of their power electronic interface, whereas the end-point connection of electronic loads, batteries, and fuel cells is exclusively dc. Therefore, merging these devices into dedicated dc distribution architectures through corresponding dc?dc converters is an attractive option not only in terms of enhancing efficiency because of reduction of conversion steps but also for realizing power quality independence from the utility mains. These kinds of systems generally provide improved reliability in comparison to their alternating current (ac) counterparts since the number of active elements in dc?dc power electronic devices is smaller than in dc-ac converters. Control design in dc systems is also significantly simpler since there are no reactive and harmonic power flows or problems with synchronization.

294 citations


Journal ArticleDOI
TL;DR: In this paper, a design method for the co-design and integration of a CMOS rectifier and small loop antenna and a complementary MOS diode is proposed to improve the harvester's ability to store and hold energy over a long period of time during which there is insufficient power for rectification.
Abstract: In this paper, a design method for the co-design and integration of a CMOS rectifier and small loop antenna is described. In order to improve the sensitivity, the antenna-rectifier interface is analyzed as it plays a crucial role in the co-design optimization. Subsequently, a 5-stage cross-connected differential rectifier with a 7-bit binary-weighted capacitor bank is designed and fabricated in standard 90 nm CMOS technology. The rectifier is brought at resonance with a high-Q loop antenna by means of a control loop that compensates for any variation at the antenna-rectifier interface and passively boosts the antenna voltage to enhance the sensitivity. A complementary MOS diode is proposed to improve the harvester's ability to store and hold energy over a long period of time during which there is insufficient power for rectification. The chip is ESD protected and integrated on a compact loop antenna. Measurements in an anechoic chamber at 868 MHz demonstrate a -27 dBm sensitivity for 1 V output across a capacitive load and 27 meter range for a 1.78 W RF source in an office corridor. The end-to-end power conversion efficiency equals 40% at -17 dBm.

289 citations


Journal ArticleDOI
TL;DR: In this paper, a dual-stator spoke array (DSSA) VPM topology was proposed to achieve high power factor and high torque capability, and the performance of the DSSA VPM was evaluated based on finite element analysis, including power factor, torque density and cogging torque.
Abstract: Vernier permanent-magnet (VPM) machines are well known for high torque density but low power factor. This paper deals with the low power factor of VPM machines. The goal is not obtained by reducing the electrical loading or adjusting current advance angle but by proposing a novel vernier topology, i.e., a dual-stator spoke-array (DSSA) VPM topology. In this paper, the characteristics of the DSSA VPM topology, such as active part, auxiliary mechanical structure, and rotor anisotropy, are analyzed in detail. Performances are evaluated based on finite-element analysis, including power factor, torque density, and cogging torque. The results show that the DSSA VPM topology exhibits high power factor, viz., ~0.9, and significantly high torque capability. The verification of the mechanical structure scheme is also done in this paper. Finally, theoretical analyses are validated by the experimental results by a 44-rotor pole 24-slot DSSA VPM prototype.

269 citations


Journal ArticleDOI
TL;DR: Reactive power support operation using offboard PEV charging stations while charging a PEV battery is investigated and a control system for the PQ command following of a bidirectional offboard charger is presented.
Abstract: The number of offboard fast charging stations is increasing as plug-in electric vehicles (PEVs) are more widespread in the world. Additional features on the operation of chargers will result in more benefits for investors, utility companies, and PEV owners. This paper investigates reactive power support operation using offboard PEV charging stations while charging a PEV battery. The topology consists of a three-phase ac-dc boost rectifier that is capable of operating in all four quadrants. The operation modes that are of interest are power-factor-corrected charging operation, and charging and capacitive/inductive reactive power operation. This paper also presents a control system for the PQ command following of a bidirectional offboard charger. The controller only receives the charging power command from a user and the reactive power command (when needed) from a utility, and it adjusts the line current and the battery charging current correspondingly. The vehicle's battery is not affected during the reactive power operation. A simulation study is developed utilizing PSIM, and the control system is experimentally tested using a 12.5-kVA charging station design.

265 citations


Journal ArticleDOI
TL;DR: In this article, a fuzzy logic controller (FLC)-based single-ended primary-induction converter (SEPIC) was proposed for maximum power point tracking (MPPT) operation of a photovoltaic (PV) system.
Abstract: This paper presents a fuzzy logic controller (FLC)-based single-ended primary-inductor converter (SEPIC) for maximum power point tracking (MPPT) operation of a photovoltaic (PV) system. The FLC proposed presents that the convergent distribution of the membership function offers faster response than the symmetrically distributed membership functions. The fuzzy controller for the SEPIC MPPT scheme shows high precision in current transition and keeps the voltage without any changes, in the variable-load case, represented in small steady-state error and small overshoot. The proposed scheme ensures optimal use of PV array and proves its efficacy in variable load conditions, unity, and lagging power factor at the inverter output (load) side. The real-time implementation of the MPPT SEPIC converter is done by a digital signal processor (DSP), i.e., TMS320F28335. The performance of the converter is tested in both simulation and experiment at different operating conditions. The performance of the proposed FLC-based MPPT operation of SEPIC converter is compared to that of the conventional proportional-integral (PI)-based SEPIC converter. The results show that the proposed FLC-based MPPT scheme for SEPIC can accurately track the reference signal and transfer power around 4.8% more than the conventional PI-based system.

Journal ArticleDOI
TL;DR: In this paper, the problem posed by complex, nonlinear controllers for power system load flows employing multi-terminal voltage source converter (VSC) HVDC systems is addressed.
Abstract: This paper addresses the problem posed by complex, nonlinear controllers for power system load flows employing multi-terminal voltage source converter (VSC) HVDC systems. More realistic dc grid control strategies can thus be carefully considered in power flow analysis of ac/dc grids. Power flow methods for multi-terminal VSC-HVDC (MTDC) systems are analyzed for different types of dc voltage control techniques and the weaknesses of present methods are addressed. As distributed voltage control is likely to be adopted by practical dc grids, a new generalized algorithm is proposed to solve the power flow problems with various nonlinear voltage droops, and the method to incorporate this algorithm with ac power flow models is also developed. With five sets of voltage characteristics implemented, the proposed scheme is applied to a five-terminal test system and shows satisfactory performance. For a range of wind power variations and converter outages, post-contingency behaviors of the system under the five control scenarios are examined. The impact of these controls on the power flow solutions is assessed.

Journal ArticleDOI
TL;DR: In this paper, a triangular current mode (TCM) rectifier with a low height of 5 mm has been realized and measurement results are provided in order to validate the theoretical considerations.
Abstract: This paper presents the analysis and realization of a topology suitable to realize a power factor correction (PFC) rectifier with a thickness of only a few millimeters. The low height of the converter requires all components to be integrated into the printed circuit board (PCB). Still reasonable dimensions of the converter PCB are feasible (221 mm × 157 mm for a 200 W PFC rectifier), since PCB-integrated inductors and capacitors allow for high energy densities due to their large surface area which facilitates a low thermal resistance to ambient. A multicell totem-pole PFC rectifier employing a soft-switching modulation scheme over the complete mains period is identified as an adequate topology. The mode of operation is entitled triangular current mode (TCM) due to the triangular-shaped inductor currents. The modulation technique requires a reliable description of the switching transition of a half-bridge in order to provide accurate timing parameters. For this purpose, a simplified model of the nonlinear MOSFETs' output capacitances facilitates closed-form analytical expressions for duty cycle and switching frequency. Furthermore, this paper details the control of three interleaved converter cells which yields a reduction of the input current ripple. A 200 W TCM PFC rectifier with a low height of 5 mm has been realized and measurement results are provided in order to validate the theoretical considerations. The presented TCM PFC rectifier achieves an efficiency of 94.6% and a power factor of 99.3% at nominal power.

Journal ArticleDOI
TL;DR: In this article, an optimal reactive power coordination strategy based on the load and irradiance forecast is proposed to minimize the number of tap operations so as not to reduce the operating life of the tap control mechanism and avoid runaway.
Abstract: The uptake of variable megawatts from photovoltaics (PV) challenges distribution system operation. The primary problem is significant voltage rise in the feeder that forces existing voltage control devices such as on-load tap-changers and line voltage regulators to operate continuously. The consequence is the deterioration of the operating life of the voltage control mechanism. Also, conventional non-coordinated reactive power control can result in the operation of the line regulator at its control limit (runaway condition). This paper proposes an optimal reactive power coordination strategy based on the load and irradiance forecast. The objective is to minimize the number of tap operations so as not to reduce the operating life of the tap control mechanism and avoid runaway. The proposed objective is achieved by coordinating various reactive power control options in the distribution network while satisfying constraints such as maximum power point tracking of PV and voltage limits of the feeder. The option of voltage support from PV plant is also considered. The problem is formulated as constrained optimization and solved through the interior point technique. The effectiveness of the approach is demonstrated in a realistic distribution network model.

Journal ArticleDOI
TL;DR: Novel linear-programming models that incorporate reactive power and voltage magnitudes in a linear power flow approximation are proposed, built on a polyhedral relaxation of the cosine terms in the AC equations as well as Taylor approximations of the remaining nonlinear terms.
Abstract: Linear active-power-only power flow approximations are pervasive in the planning and control of power systems However, AC power systems are governed by a system of nonlinear nonconvex power flow equations Existing linear approximations fail to capture key power flow variables, including reactive power and voltage magnitudes, both of which are necessary in many applications that require voltage management and AC power flow feasibility This paper proposes novel linear-programming models (the LPAC models) that incorporate reactive power and voltage magnitudes in a linear power flow approximation The LPAC models are built on a polyhedral relaxation of the cosine terms in the AC equations as well as Taylor approximations of the remaining nonlinear terms Experimental comparisons with AC solutions on a variety of standard IEEE and Matpower benchmarks show that the LPAC models produce accurate values for active and reactive power, phase angles, and voltage magnitudes The potential benefits of the LPAC model

Journal ArticleDOI
TL;DR: A straightforward procedure is developed to tune the lead-lag network with the help of software tools and the rationale of this procedure, based on the capacitor current feedback, is elucidated.
Abstract: Three-phase active rectifiers guarantee sinusoidal input currents and unity power factor at the price of a high switching frequency ripple. To adopt an LCL-filter, instead of an L-filter, allows using reduced values for the inductances and so preserving dynamics. However, stability problems can arise in the current control loop if the present resonance is not properly damped. Passive damping simply adds resistors in series with the LCL-filter capacitors. This simplicity is at the expense of increased losses and encumbrances. Active damping modifies the control algorithm to attain stability without using dissipative elements but, sometimes, needing additional sensors. This solution has been addressed in many publications. The lead-lag network method is one of the first reported procedures and continues being in use. However, neither there is a direct tuning procedure (without trial and error) nor its rationale has been explained. Thus, in this paper a straightforward procedure is developed to tune the lead-lag network with the help of software tools. The rationale of this procedure, based on the capacitor current feedback, is elucidated. Stability is studied by means of the root locus analysis in z-plane. Selecting the lead-lag network for the maximum damping in the closed-loop poles uses a simple optimization algorithm. The robustness against the grid inductance variation is also analyzed. Simulations and experiments confirm the validity of the proposed design flow.

Journal ArticleDOI
TL;DR: In this paper, a two-stage onboard battery charger is analyzed for plug-in electric vehicles (PEVs), and an interleaved boost topology is employed in the first stage for power factor correction (PFC) and to reduce total harmonic distortion (THD).
Abstract: In this paper, a two-stage onboard battery charger is analyzed for plug-in electric vehicles (PEVs). An interleaved boost topology is employed in the first stage for power factor correction (PFC) and to reduce total harmonic distortion (THD). In the second stage, a full-bridge LLC-based multiresonant converter is adopted for galvanic isolation and dc/dc conversion. Design considerations are discussed, focusing on reducing the charger volume and optimizing the conversion efficiency over the wide battery-pack voltage range. A detailed design procedure is provided for a 1-kW prototype, charging the battery with an output voltage range of 320–420 V from 110-V 60-Hz single-phase grid. Experimental results show that the first-stage PFC converter achieves THD of less than 4% and a power factor higher than 0.99, and the second-stage LLC converter operates with 95.4% peak efficiency and good overall efficiency over wide output voltage ranges.

Journal ArticleDOI
TL;DR: In this article, an active power filter implemented with a four-leg voltage-source inverter using a predictive control scheme is presented, which allows the compensation of current harmonic components, as well as unbalanced current generated by single-phase nonlinear loads.
Abstract: An active power filter implemented with a four-leg voltage-source inverter using a predictive control scheme is presented. The use of a four-leg voltage-source inverter allows the compensation of current harmonic components, as well as unbalanced current generated by single-phase nonlinear loads. A detailed yet simple mathematical model of the active power filter, including the effect of the equivalent power system impedance, is derived and used to design the predictive control algorithm. The compensation performance of the proposed active power filter and the associated control scheme under steady state and transient operating conditions is demonstrated through simulations and experimental results.

Journal ArticleDOI
TL;DR: In this paper, the integration of solar photovoltaic (PV) and battery energy storage (BES) units for reducing energy loss and enhancing voltage stability is discussed, where each non-pitchable PV unit is converted into a dispatchable source with a combination of PV and BES units.

Journal ArticleDOI
TL;DR: This work shows how using specifically selected or designed waveforms in wireless power transfer systems can lead to improved RF to dc conversion efficiency in rectifier circuits in the receiving end of these systems.
Abstract: This work shows how using specifically selected or designed waveforms in wireless power transfer (WPT) systems can lead to improved RF to dc conversion efficiency in rectifier circuits in the receiving end of these systems Signals with different time domain waveforms are considered such as OFDM, white noise and chaotic waveforms, and the performance of a rectifier circuit operating at 433 MHz is evaluated when using these signals in comparison to a single carrier constant envelope signal The performed experiments show that selecting high peak to average power ratio (PAPR) signals lead to improved RF-DC conversion efficiency in rectifier circuits

Journal ArticleDOI
TL;DR: In this article, an approximate small-signal model of a power supply that describes how the power supply reacts to a perturbation in its input is derived using the generalized state-space averaging technique.
Abstract: This paper analyzes the dynamics of an LCL- $T$ -based inductive power transfer power supply, and aims to improve its reference tracking performance for dynamic roadway wireless powering applications using a digital PI controller. An approximate small-signal model of the power supply that describes how the power supply reacts to a perturbation in its input is derived using the generalized state-space averaging technique. The model is verified experimentally and shown to capture the supply dynamics. Limitations of the model and their implications are also discussed. Using the small-signal model, a closed-loop digital PI controller is designed to ensure a fast turn-on of a 20 kHz power supply at no-load in approximately 300 μs with no overshoot in the track current.

Journal ArticleDOI
TL;DR: In this article, a reactive power control is proposed to regulate the maximum and minimum phase voltages at the point of common coupling within the limits established in grid codes for continuous operation, which can help to mitigate the adverse effects of these perturbations by injecting the reactive power during the sag and the postfault operation.
Abstract: Grid faults are one of the most severe problems for network operation. Distributed generation power plants can help to mitigate the adverse effects of these perturbations by injecting the reactive power during the sag and the postfault operation. Thus, the risk of cascade disconnection and voltage collapse can be reduced. The proposed reactive power control is intended to regulate the maximum and minimum phase voltages at the point of common coupling within the limits established in grid codes for continuous operation. In balanced three-phase voltage sags, the control increases the voltage in each phase above the lower regulated limit by injecting the positive sequence reactive power. In unbalanced voltage sags, positive and negative sequence reactive powers are combined to flexibly raise and equalize the phase voltages; the maximum phase voltage is regulated below the upper limit and the minimum phase voltage just above the lower limit. The proposed control strategy is tested by considering a distant grid fault and a large grid impedance. Selected experimental results are reported in order to validate the behavior of the control scheme.

Journal ArticleDOI
TL;DR: In this article, a predictive-control-based direct power control (DPC) with an adaptive online parameter identification technique for ac-dc active front ends (AFEs) is proposed to overcome model mismatch and parameter uncertainty.
Abstract: This paper proposes predictive-control-based direct power control (DPC) with an adaptive online parameter identification technique for ac-dc active front ends (AFEs) to overcome model mismatch and parameter uncertainty. Based on least-squares estimation, the input inductance and input resistance of the AFE are calculated every sampling period using sampled input currents and input voltages. Because the online-tuned input inductance and resistance are updated for the controller, the proposed predictive-control-based DPC with the adaptive parameter identification technique can mitigate performance degradation resulting from the model uncertainty of the model predictive controller without any additional sensors. Therefore, the AFE generates sinusoidal input currents with a unity power factor despite parameter uncertainty.

Journal ArticleDOI
TL;DR: This paper presents a power factor corrected (PFC) bridgeless (BL) buck-boost converter-fed brushless direct current (BLDC) motor drive as a cost-effective solution for low-power applications.
Abstract: This paper presents a power factor corrected (PFC) bridgeless (BL) buck-boost converter-fed brushless direct current (BLDC) motor drive as a cost-effective solution for low-power applications. An approach of speed control of the BLDC motor by controlling the dc link voltage of the voltage source inverter (VSI) is used with a single voltage sensor. This facilitates the operation of VSI at fundamental frequency switching by using the electronic commutation of the BLDC motor which offers reduced switching losses. A BL configuration of the buck-boost converter is proposed which offers the elimination of the diode bridge rectifier, thus reducing the conduction losses associated with it. A PFC BL buck-boost converter is designed to operate in discontinuous inductor current mode (DICM) to provide an inherent PFC at ac mains. The performance of the proposed drive is evaluated over a wide range of speed control and varying supply voltages (universal ac mains at 90-265 V) with improved power quality at ac mains. The obtained power quality indices are within the acceptable limits of international power quality standards such as the IEC 61000-3-2. The performance of the proposed drive is simulated in MATLAB/Simulink environment, and the obtained results are validated experimentally on a developed prototype of the drive.

Journal ArticleDOI
TL;DR: In this paper, a parallel IPT power supply topology that can achieve high output power levels in a cost effective manner is presented, which can minimize uneven power sharing due to component tolerance and does not require any additional reactive components for parallelization.
Abstract: High-power inductive power transfer (IPT) systems operate at power levels of 100 kW or more. However, existing high-power IPT power supplies are typically designed for one power level and are expensive to make, due to the use of high-power electronic components. This paper presents a parallel IPT power supply topology that can achieve high output power levels in a cost effective manner. The parallel topology can minimize uneven power sharing due to component tolerance, and does not require any additional reactive components for parallelization. In addition, it can continue to operate when a faulty parallel unit is electronically shut down, dramatically improving the availability and reliability of the systems. Furthermore, flexible output power levels may be achieved by connecting identical modules in parallel. A 6 kW parallel power supply has been constructed by connecting three 2 kW power supplies in parallel. The maximum efficiency of the power supply and track is measured to be 94%.

Journal ArticleDOI
TL;DR: In this paper, the reliability aspects of power electronic techniques are discussed in the context of high-efficiency power conversion for adjustable-speed drives, power quality correction, renewable energy systems, energy storage systems, and electric vehicles.
Abstract: Power electronic systems play an increasingly important role in providing high-efficiency power conversion for adjustable-speed drives, power-quality correction, renewable-energy systems, energy-storage systems, and electric vehicles. However, they are often presented with demanding operating environments that challenge the reliability aspects of power electronic techniques. For example, increasingly thermally stressful environments are seen in applications such as electric vehicles, where ambient temperatures under the hood exceed 150 °C, while some wind turbine applications can place large temperature cycling conditions on the system. On the other hand, safety requirements in the aerospace and automotive industries place rigorous demands on reliability.

Journal ArticleDOI
TL;DR: In this article, a modulation strategy has been proposed that results in 1) open-loop power factor correction; 2) zero current switching in the ac-side converter for all load conditions; 3) linear power relationship for easy control implementation; and 4) zero voltage switching in a load side converter.
Abstract: A dual-active-bridge-based single-stage ac/dc converter may find a wide range of emerging applications such as interfacing plug-in hybrid vehicles with the ac grid, interconnection of dc grid, etc. This type of converter can be used due to unique features such as 1) high-frequency isolation resulting in a) high power density and b) safety and voltage matching; 2) bidirectional power flow; 3) soft switching leading to higher efficiency. In this paper, a modulation strategy has been proposed that results in 1) open-loop power factor correction; 2) zero current switching in the ac-side converter for all load conditions; 3) linear power relationship for easy control implementation; and 4) Zero voltage switching in the load side converter. The converter with the proposed control has been analyzed. Simulation and experimental results on a 1-KW prototype confirm the advantages.

Journal ArticleDOI
TL;DR: In this article, a proportional-resonant, multiloop controller is proposed to reduce the number of resonators in a synchronous reference frame, compared with the solution using proportional-integral controllers in the harmonic-reference frame.
Abstract: This paper deals with reactive power compensation and harmonics elimination in medium-voltage industrial networks using a hybrid active power filter. It proposes a hybrid filter as a combination of a three-phase, two-level, voltage-source converter connected in parallel with the inductor of a shunt, single-tuned, passive filter. This topological structure greatly decreases the voltage and current stress over the elements of the active filter. Since the topology is composed of a single-tuned branch, the control algorithm also has to ensure sufficient filtering at other harmonic frequencies. We propose using a proportional-resonant, multiloop controller. Since the controller is implemented in a synchronous-reference frame, it allows us to use half the number of resonators, compared with the solution using proportional-integral controllers in the harmonic-reference frame. Theoretical analyses and simulation results obtained from an actual industrial network model in PSCAD verify the viability and effectiveness of the proposed hybrid filter. In addition, the simulation results are validated by a comparison with the results obtained from a real-time digital simulator.

Journal ArticleDOI
TL;DR: It is pointed out that when the minimum nonactive power loss is achieved, zero-voltage soft switching can be naturally fulfilled and the optimal phase-shift pair obtained by the proposed method can keep low values of both root mean square (RMS) current and circulating power.
Abstract: Originated from analyzing nonactive power loss, a novel optimization method and modulation solution for bidirectional isolated dual-active-bridge (DAB) dc-dc converters are proposed in order to achieve high efficiency in a wide operating range. A comprehensive nonactive power loss model is developed, including both the nonactive components delivered back to the source and from the load. This paper points out that when the minimum nonactive power loss is achieved, zero-voltage soft switching can be naturally fulfilled. The optimal phase-shift pair obtained by the proposed method can keep low values of both root mean square (RMS) current and circulating power. Rather than using ideal power flow analysis, the nonactive power loss model directly embodies practical nonideal factors, including device voltage drops. Based on the analysis, an extended dual phase shift is proposed, and different operation cases are analyzed with comparison of performance indices. Experimental tests verify the theoretical analysis and show effectiveness of the proposed approach to achieve nonactive power loss minimization and efficiency improvement.

Journal ArticleDOI
TL;DR: A full-bridge boost power converter topology is studied for power factor control, using output higher order sliding mode control, and multi-rate simulation illustrates the effectiveness and robustness of the proposed controller in the presence of measurement noise.
Abstract: In this paper, a full-bridge boost power converter topology is studied for power factor control, using output higher order sliding mode control. The AC/DC converters are used for charging the battery and super-capacitor in hybrid electric vehicles from the utility. The proposed control forces the input currents to track the desired values, which can control the output voltage while keeping the power factor close to one. Super-twisting sliding mode observer is employed to estimate the input currents and load resistance only from the measurement of output voltage. Lyapunov analysis shows the asymptotic convergence of the closed-loop system to zero. Multi-rate simulation illustrates the effectiveness and robustness of the proposed controller in the presence of measurement noise.