1,720,995 research outputs found
On-line Junction Temperature Estimation of SiC Power MOSFETs
Full text linkL'abstract è presente nell'allegato / the abstract is in the attachmen
A Novel Two-Phase Permanent Magnet Rotor Machine for Automotive Applications
Full text linkThis paper presents a study of permanent magnet machines for automotive applications, comparing different slot, pole and phase number combinations in terms of torque and power output and NVH performance under constraint of the same active volume. FEM simulations are used to estimate electromagnetic performance and an analytical model to evaluate noise emissions for each configuration. In this analysis, a novel two-phase machine with mildly overlapped windings emerges as the best combination between NVH and electromagnetic performance, at the expense of a 4-leg power converter instead of a standard 3-phase 2-level inverter
Dynamic Redistribution of Switching Losses in Parallel Connected SiC MOSFETs for Active Thermal Balance
No full textSelf-Calibration Technique for Junction Temperature Estimation of SiC MOSFET Inverters Loaded with Synchronous Reluctance Motors
Full text linkSiC devices have pushed the boundaries of power electronic conversion to new limits of power density and efficiency, but they also require appropriate thermal management. The conduction resistance of a SiC MOSFET is an indirect indicator of its junction temperature, provided that the R-ON versus temperature and current characteristic of the device is preliminarily mapped. Such R-ON map is normally obtained using dedicated test rigs, with the inverter connected to a custom inductive load. In this work, the R-ON maps of the power devices of a 3-phase Voltage Supply Inverter are obtained via self-calibration with the converter already connected to the target synchronous reluctance motor, without requiring rotor movements nor dedicated measurement equipment. The proposed procedure consists of a preliminary self-heating stage followed by R-ON mapping through current pulses along the zero-torque directions of the rotor reference frame. The connection to the target motor reduces the measurement domain in terms of maximum current and temperature with respect to the custom load. A polynomial model is used to extrapolate the R-ON characteristic out of the measurement domain, showing high estimation accuracy. Preliminary experimental results are presented
Novel DPT-Based SPICE Modeling Approach for Enhanced Prediction of Parallel SiC MOSFET Switching Dynamics
No full textDirect Flux-and-Torque Vector Control with Active Torque Ripple Minimization
Full text linkThe paper presents a simple and effective direct flux and torque control strategy for the active minimization of torque ripple in Permanent Magnet synchronous motor drives. The observed stator flux amplitude and the estimated electromagnetic torque are directly controlled, and the torque feedback is estimated through a pre-determined 3D Look-UpTable having the (d, q) current components and the measured rotor phase angle theta as inputs. The torque LUT used in the paper was obtained via dedicated preliminary experimental tests, but other methods for its determination exist, including Finite Element Analysis where possible, and manipulation of the flux d, q linkage characteristics. Simulation and experimental results are provided for a 10kW Permanent Magnet Synchronous Motor to demonstrate the validity of the proposed torque control strategy
Comparative Study of DC-Link Capacitor Size for Two and Three Phase Permanent Magnet Synchronous Machines
No full textTwo-phase open winding electrical machines have been proposed in the literature for their benefits in terms of peak torque and low noise emission. For this type of open-winding motors, a 4-leg power converter is required, allowing a power increase of 15% at the cost of one additional converter leg. This paper focuses on the impact of the two-phase open winding solution on the size of the DC-link capacitors, which is not covered in the literature. With reference to a state-of-the-art concentrated-winding 12slot/10pole 3ph PMSM drive, the DC-link RMS current stress and voltage ripple are comparatively analysed for different operating conditions. The simulations show that, under the same mechanical power conditions, the DC-link capacitor in the two-phase machine experiences lower voltage stress and similar RMS current compared to its three-phase counterpart. This effect impacts the cost, volume, and weight of the DC-link capacitor, partially compensating for the additional inverter leg required by the two-phase solution
Enhanced Short-Time Thermal Transient Model and Testing Procedure for High Power Density Motors, Such as in Supercar Traction
No full textThe short-time thermal transient (STTT) test is an efficient and precise method for determining the winding thermal capacitance and winding-to-back-iron thermal resistance in ac motors. Traditionally validated for industrial motors, the STTT procedure involves a brief dc excitation with motor phases connected in series, followed by analysis using a first-order lumped parameter thermal network. However, for traction motor drives where phase terminals may be inaccessible, the standard all-in-series STTT procedure is not feasible. Moreover, in such highly loaded traction motors, the estimated thermal parameters are sensitive to dc excitation duration, making the first-order STTT model unsuitable. This article presents an STTT model of higher order along with an optimized testing sequence and data processing approach, extending the applicability of this method to traction and high-power-density motors. Experimental validation on two commercial supercar traction motors demonstrates the effectiveness of the proposed model and procedure, to be considered an upgrade of wider and more general validity of the existing first-order STTT method
Fast Overcurrent Protection for Direct Drive Cascode GaN HEMT Semiconductors Based on Industrial Gate Drivers
Full text linkGallium nitride high electron mobility transistors exhibit excellent switching and conduction performance. However, their adoption in safety-critical applications is subject to concerns about their capability to withstand severe overcurrents. Therefore, fast and reliable overcurrent protections are needed to guarantee the safe operation of the power switches. The conventional desaturation protection methods, widely used for MOSFETs and IGBTs, do not match with the reduced shortcircuit capability of new GaN HEMTs semiconductors. To address this issue, this paper proposes a fast overcurrent protection scheme specifically designed for direct drive cascode GaN HEMT. The proposed solution uses an industrial gate driver along with a few additional components, leveraging the measurement of the conduction voltage of the cascode MOSFET as an indirect indicator of the device current with very good precision and reduced intervention time. The effectiveness of the proposed overcurrent protection scheme is supported by experimental results
Grid Fault Current Injection using Virtual Synchronous Machines featuring Active Junction Temperature Limitation of Power Devices
Full text linkThe recent years have seen an exponential growth in the electric generation from renewable energy sources, such as wind and sun. This scenario represents an opportunity to decarbonize part of the energy sector and phase out fossil fuels. However, particular care must be taken to ensure the correct operation of the electric grid. With a large penetration of power electronics based generation, special care must be taken in case of grid faults, due to limited short circuit current capabilities of static converters, supporting the grid in case of faults. For this reason, static converters have to be transiently overloaded to inject fault currents larger than their nominal limit, mimicking the behavior of synchronous generators. Therefore, this paper proposes the combined solution of a transiently overloadable virtual synchronous machine (VSM) converter equipped with real-time semiconductor junction temperature limitation. The VSM provides the necessary short circuit current references and the inverter can be overloaded with an active thermal control strategy, avoiding the oversizing of the power semiconductors, by properly exploiting their thermal limits. This represents a possible path for further power electronics integration into the grid
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