1,720,993 research outputs found
Small Footprint Inductive Power Transfer Based on Split-Transformer: Design and Experimental Validation
No full textEffect 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
Single-phase current source inverter with reduced ground leakage current for photovoltaic applications
Full text linkIntegrated power electronics for photovoltaic applications has attracted increasing interest, due to the possibility of having grid-connected photovoltaic modules with independent maximum power point tracking and high reliability. In this paper, a single-phase Current Source Inverter (CSI) is discussed for a photovoltaic application. The basic CSI topology will be explained for the sake of completeness, highlighting its main features and analyzing the ground leakage current problem, an important benchmark for photovoltaic application. A novel topology, called CSI5, is proposed in this work. The main feature is the presence of additional switches for ground leakage current reduction. The performance of the proposed topology is assessed by numerical simulation, and the experimental results confirm that this solution is able to strongly reduce the ground leakage current and conduction power losses
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
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%
A Time-Saving Approach for the Thermal Lifetime Evaluation of Low-Voltage Electrical Machines
No full textModern electrical machines, such as those employed in transportation applications are required to provide very high performance in terms of power (and torque) density and efficiency. The reality, however, is that the more these machines are 'pushed' in relation to power density, the more is the probability of failure of their insulation systems, through enhanced electrical and thermal stresses. On the other hand, regardless the power density level, the electrical machine still needs to respect the certification processes set by the international standards and procedures. Unfortunately, today reliability and lifetime are still not considered as main design objective functions right from the start of the design process. This is a direct result of a gap in knowledge in terms of the precise understanding of failure mechanisms. If physics of failure models are available, then reliability can be included at all design stages. Therefore, this article proposes a method that shortens the time demanded for the thermal lifetime evaluation procedure or qualification of low-voltage electrical machines. The theory behind the method is presented and, then, experimentally validated on custom designed specimens
Reconfigurable Multi-Three-Phase Drive for Naval Rim-Driven Propulsion System
No full textMultiphase drives are the subject of great interest for the transportation electrification. Multi-three-phase machines are used with modular three-phase converters to obtain a redundant structure and their great advantage is the fault-tolerance capability. Starting from a symmetrical multi-three-phase machine, a reconfigurable architecture drive can be obtained. The main characteristic of a reconfigurable architecture is the ability to change the winding configuration to better match the operating point, specifically the machine speed. The main advantage of this architecture is the capability of reducing the number of active converters when the machine operates at low speed, thus reducing total converter power losses. However, system complexity increases, since reconfiguration cells are needed to interconnect the winding sets. The proposed reconfigurable multi-three-phase drive architecture exhibits two main benefits at low speed operation: increased efficiency and reduced phase current ripple for a given switching frequency. The reconfigurable architecture was assessed by means of analytical as well as numerical simulations, and the benefits obtainable at low speed operation were also demonstrated experimentally on a reduced scale prototype, capable of 'on the fly' reconfiguration without stopping the machine
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