1,721,004 research outputs found
Ground Leakage Current in Three-Phase Current Source Inverters Depending on Power Semiconductors Parasitic Capacitances
No full textThis paper analyzes the relation between the ground leakage current and the power semiconductor parasitic components of a three-phase Current Source Inverter (CSI) topology named in literature H7 or CSI7. This topology is characterized by the presence of an additional switch which allows to reduce conduction power losses and decouple the DC side from the AC side during the application of the Zero current Vector to reduce ground leakage current. This work deals with the significant variation of this current depending on power converter parasitic capacitors. In this work the analysis is applied to grid-connected converters for a string photovoltaic applications, even if the behavior is the same also in case of electrical drives. The analysis is assessed by numerical simulations and experimental results with different parasitic capacitances that confirm also the validity of the proposed equivalent common-mode circuit
Improved SVM Pattern for Single-Stage CSI With Discharge Path in Electric Drives Applications
No full textA recently proposed single-stage current source inverter (CSI) with discharge path exhibits the ability to control the drive from zero speed without the insertion of an additional pre-stage converter to control the input dc current. The size of the dc input inductor can be reduced to minimize the volume and weight of the power converter. With this choice, the output currents exhibit large distortion for the entire discontinuous conduction mode (DCM). The present work proposes a novel modulation pattern specific for the low-speed region in terms of reduction of the total harmonic distortion (THD). A fair comparison between the proposed pattern and the classical one is obtained, considering the same number of commutations per time unit. Simulations and experimental results confirm the validity and the considerable THD decrease of the proposed space vector modulation (SVM) pattern for the single-stage CSI with discharge path topology. In particular, the advantage is clear under DCM condition where the base pattern exhibits a large THD up to 15%, while the proposed one has an overall lower THD, with a maximum value of 8%
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Assessment of master-slave and droop control strategies in multi-three-phase drives
No full textMulti-phase electric drives can be employed in a great variety of applications. Their advantage in terms of fault-tolerance capability is becoming the focus of the work of many research activities, especially in the field of transportation electrification. The main topic is to create redundant and modular multi-three-phase drives to increase the overall system reliability and fault-tolerance. To this aim, distributed control architectures have been assessed. In this paper, a centralized master-slave control is compared against a distributed droop control architecture, in order to identify advantages and drawbacks. Both of the control strategies are applied to a double three-phase drive. The aim of the work is to assess whether the droop control architecture can be a valid alternative to a centralized master-slave control in terms of performances, but with the additional benefit of having a proper full redundant fault-tolerant application
Iron Losses Impact on High-Speed Drives
No full textHigher magnitudes of the stator currents, low efficiency, and degradation of the output torque in high speed machine are caused by iron losses, which are not sufficiently small to be neglected. A Finite Control Set Model Predictive Control (FCS-MPC) which takes iron losses into account in the prediction model on a high speed motor is proposed in this paper and compared to classical FCS-MPC that neglects iron losses influence. Performances of both models are analysed and compared under steady-state and transient conditions including acceleration condition using a 3-Level Hybrid Active Neutral Point Clamped (HANPC) inverter topology. Accurate simulations of a 3-Level HANPC inverter driving a high speed PMSM are presented comparing the proposed control respect to classical FCS-MPC and the classical Field Oriented Control (FOC) together with neutral point (NP) balance and loss minimization control (LMC)
Optimized Parallel Hybrid Amplifier for Print-Head Piezoelectric Actuators with Trapezoidal Waveforms
No full textMost of the drivers used to control high-frequency print-head piezoelectric actuators are based on linear technology (e.g., Class AB amplifiers) which dissipate a large amount of power for this specific application. This choice is given by the necessary of very precise tracking and large bandwidth for the closed-loop voltage control of the piezoelectric load. This work highlights the critical issues of pure Class D amplifiers and hybrid (switching and linear) solutions. Then a new hybrid power amplifier topology is proposed analyzing its advantages and drawbacks for these kind of piezoelectric loads reducing energy consumption. First of all, the performance of the proposed solution is verified by simulations in LTspice environment. Experimental results showed the effectiveness of the proposed solution potentially paving the way to a larger adoption of this topology for high-frequency piezoelectric actuators. The proposed solution is patent pending
Effect of semiconductor parasitic capacitances on ground leakage current in three-phase current source inverters
Full text linkThis paper investigates the influence of power semiconductor parasitic components on the ground leakage current in the three-phase Current Source Inverter topology, in the literature called H7 or CSI7. This topology allows reducing converter conduction losses with respect to the classic CSI, but at the same time makes the topology more susceptible to the parasitic capacitances of the semiconductors devices. In the present work, a grid-connected converter for photovoltaic power systems is considered as a case study, to investigate the equivalent circuit for ground leakage current. The same analysis can be extended to applications regarding electric drives, since the HF model of electric machines is characterized by stray capacitance between windings and the stator slots/motor frame. Simulation results proved the correctness of the proposed simplified common-mode circuit and highlighted the need of an additional common-mode inductor filter in case of resonance frequencies of the common-mode circuit close to harmonics of the power converter switching frequency. Experimental results are in agreement with the theoretical analysis
Extended Speed Range Control for a Current Source Inverter Variable Speed Drive
No full textVoltage Source Inverters (VSIs) are usually adopted for high-speed motor drive applications due to the topology simplicity and the wide availability of control strategies for this topology. An alternative is the Current Source Inverter (CSI) which allows to achieve high speed range with limited DC voltage due to its intrinsic boost capability, and this is of interest in aerospace applications or electrical vehicles (EV), but a pre-stage is necessary to control the DC input current. In this work an hybrid solution is proposed to extend the speed range of a single stage CSI (i.e. CSI without pre-stage) driving a Permanent Magnet Synchronous Machine (PMSM). In fact using a single stage CSI with DC current control, the machine cannot work properly in low speed region, so the control is composed by two different strategies: one is proposed in this work for low speed operations and the other one is already known for high speed
Novel Single-Stage Current Source Inverter: Extension to Low-Speed Region in Motor Drive Applications
No full textIn motor drive applications, single-stage current source inverters (CSIs) can manage only a limited
speed range when the output voltage is greater than input
voltage, due to the intrinsic boost capability. The classical
solution adopted in low-speed region to control the input
dc current, consists in the insertion of a prestage power
converter. This article proposes a single-stage CSI that replaces the input inductance Ldc with coupled inductor. In
this way, it is possible to add the needed time interval for
the discharge of the magnetic energy of primary inductance
Lm when the converter works in low-speed region or at
standstill, extending the operating region of the converter.
This solution allows to increase the efficiency of traditional
CSIs for applications when the motor works most of the
time in the high-speed region, thanks to the single-stage
power conversion. Experimental and simulation results
driving a permanent magnet synchronous machine are
shown, confirming the validity of the proposed architecture
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