282 research outputs found
Two-leg three-phase inverter control for STATCOM and SSSC applications
Flexible ac transmission systems (FACTS) devices are attracting an increasing interest both in power system academic research and in electric utilities for their capabilities to improve steady-state performance as well as system stability. Several converter topologies for FACTS applications have been proposed in the recent literature, even if those based upon voltage source inverters (VSI) seem to be more attractive due to their intrinsic capability to rapidly respond to network changes such as perturbations subsequent to a fault and their property of being immune to resonance problem. In this paper, a new topology for inverter-based FACTS is proposed. This configuration, employing a two-leg three-phase inverter is employed for both series and parallel-connected reactive power compensators. The converter utilizes a modular topology for allowing a satisfaction of electronic components rating. A control strategy based on variable structure control technique with sliding mode is employed to track appropriate reference quantities. Design and control, as well as good tracking performances, are also verified through numerical simulations
Online thermal parameter identification for permanent magnet synchronous machines
Temperature monitoring of permanent magnet synchronous machines (PMSMs) is of great importance because high temperatures can significantly shorten the lifetimes of motor components. Accurate temperature predictions can be achieved using reduced-order lumped parameter thermal networks (LPTNs) with accurate thermal parameters. In this study, an online estimation method based on the recursive Kalman filter algorithm is introduced for online identification of the thermal resistances in a three-node LPTN representing motor stator iron, stator winding and permanent magnet. The identification procedure requires a rotor temperature measurement, which is provided by an accurate pulse-width modulation-based estimation method. The proposed methodology is experimentally validated and applied to real-time fault detection of the motor cooling system
Modelling framework for parallel SiC power MOSFETs chips in modules developed by planar technology
This paper presents a modelling framework to simulate transients and steady state performance for SiC power MOSFETs modules. The electro-thermal modelling is implemented using Simscape/MATLAB program based on the single chip characteristics provided in the datasheet. The method can easily incorporate multiple chips and module parasitic components providing a tool for module characterization and to support module design optimization. The simulated model is then experimentally validated at different voltage buses and junction temperatures for a novel SiC MOSFET Module design consists of two parallel chips per switch developed using wire-bond free planar technology
A general modelling technique for a triple redundant 3x3-phase PMA SynRM
A general modelling technique is proposed
for a triple redundant 3x3-phase permanent magnet
assisted synchronous reluctance machine (PMA SynRM).
The magneto-motive force (MMF) of the machine is
divided into three parts each associated with one 3-phase
set. The MMF of each 3-phase set can be described by
four variables: d- and q-axis components of the currents,
the rotor angle and an MMF offset component which
captures the mutual coupling between three 3-phase sets.
Therefore the complete machine behavior in all operating
conditions can be captured by means of 4-dimensional
(4D) tables, which store the flux linkage and torque
information. The 4D tables are produced by finite element
(FE) analysis for one 3-phase set. As a result, the machine
behavior can be predicted by interpolating the 4D tables.
The model is capable of representing healthy and fault
operations, including unequal current operation in three 3-
phase sets, and offers great flexibility for performance
assessment, post fault control and fault detection. Its
effectiveness is verified by extensive FE simulation and
experimental tests in different operation modes
Thermal modeling of hollow conductors for direct cooling of electrical machines
A direct cooling design using hollow conductors with the coolant flowing inside can significantly improve the heat dissipation in an electrical machine. To predict the thermal performances of an electrical machine with such cooling configuration, this paper proposes a computationally efficient thermal model of hollow conductors with direct cooling features. The hollow conductor is modeled using four equivalent solid cuboidal elements with a three-dimensional thermal network and internal heat generation. The heat transfer coefficient between the coolant and conductors is determined by an empirical model considering fluid dynamics behaviors. Axial discretization is performed to take into account the nonuniform temperature distribution along the axial direction. Experimental validation is performed with a U-shaped hollow conductor test rig. Compared to computational fluid dynamics analysis, the proposed thermal model is much more computationally efficient, and thus can be incorporated into design optimization process and electrothermal simulations of the electrical machine over a driving cycle
Investigation into Fault Tolerant Capability of a Triple Redundant PMA SynRM Drive
Fault tolerant machine drives are being favored
in safety critical applications, thus they are being actively
investigated. However, most of the solutions address the winding
or switch open circuit only, which is insufficient since intra-phase
and inter-phase turn short circuits are more likely in the machine
drives as a result of insulation degradation, and the consequences
are usually catastrophic. Magnets and capacitor may also fail and
cause damage during operation. All these faults should be
properly addressed in fault tolerant machine drives for safety
critical applications. Hence, a triple redundant, 9 phase
(3x3phase) permanent magnet assisted synchronous reluctance
machine (PMA SynRM) drive is presented by investigating the
fault tolerances against various faults. The different fault
behaviors are evaluated and the corresponding fault tolerant
capabilities are analyzed. The machine fault tolerance is
examined on a 35kW prototype drive. Both the analysis and
experimental tests demonstrate that the machine drive exhibits
excellent fault tolerant capability under most common types of
faults, including the intra-phase and inter-phase short circuit,
uncontrolled rectification, demagnetization and DC capacitor
fault
Active thermal management for Interior Permanent Magnet Synchronous Machine (IPMSM) drives based on model predictive control
This paper proposes an active thermal management scheme for Interior Permanent Magnet Synchronous Machine (IPMSM) drives based on the model predictive control concept. The proposed control scheme can adaptively set torque limit based on the thermal state of the machine to limit the machine winding and end-winding temperatures. The proposed control scheme is assessed by experiments on a laboratory machine drive system and simulated for traction drives over Worldwide Harmonized Light-duty Test Cycle (WLTC). Compared with conventional traction control scheme, the proposed scheme can effectively reduce peak temperature and hence thermal stress of the machine for improving its lifetime
Experimental assessments of a triple redundant 9-phase fault tolerant PMA SynRM drive
Fault tolerant machine drives are key enabling technologies in safety critical applications. The machine drives are expected to exhibit high performance in healthy conditions and accommodate as many faults as possible, namely open circuit or short circuit in the machine and inverter or even an inter-turn short circuit. This paper aims to assess a triple redundant 9-phase (3x3-phase) permanent magnet assisted synchronous reluctance machine (PMA SynRM) drive by comprehensive experimental tests under both healthy and fault conditions on a 35kW machine drive prototype. The healthy performance, fault behavior, fault detection and fault mitigation strategy are presented and assessed by extensive tests which demonstrate that the machine drive exhibits high performance and excellent fault tolerance with simple and cost-effective implementation. Therefore, the proposed machine drive has proven to be a practical candidate for safety critical applications
Stator turn fault detection by 2nd harmonic in instantaneous power for a triple redundant fault-tolerant PM drive
Fast and reliable detection of stator faults is of key importance for fail-safe and fault tolerant machine drives in order to immediately trigger appropriate fault mitigation actions. The paper presents a detailed analytical and experimental analysis of the behavior of a closed loop controlled permanent magnet machine drive under inter-turn fault conditions. It is shown that significant 2nd harmonic components in the dq voltages, currents, instantaneous active power (IAP) and reactive power (IRP) are generated during turn fault conditions. The analyses further show that the increase of the 2nd harmonic in IAP and IRP during fault conditions is comparatively higher than that of voltage and current, making them ideal candidates as turn fault indicators. A turn fault detection technique based on 2nd harmonic in IAP and IRP is implemented and demonstrated for a triple redundant, fault tolerant permanent magnet assisted synchronous reluctance machine (PMA SynRM) drive. The effectiveness of the proposed detection technique over the whole operation region is assessed, demonstrating fast and reliable detection over most of the operating region under both motoring and generating mode
Real-time Measurement of Temperature Sensitive Electrical Parameters in SiC Power MOSFETs
This paper examines a number of techniques
for junction temperature estimation of SiC MOSFETs
devices based on the measurement of Temperature
Sensitive Electrical Parameters (TSEPs) for use in online
condition monitoring. Linearity, sensitivity to temperature
and circuit design for practical implementation are
discussed in detail. A demonstrator based on the
measurement of the quasi-threshold voltage, the turn-on
transient characteristic (di/dt), the on-state voltage and the
gate current peak is designed and validated. It is shown that
the threshold voltage, the estimation of the gate current
peak and the on-state voltage have potentially good
sensitivity to temperature variation and linearity over a wide
operating range. Very low sensitivity to temperature is
shown for (di/dt). The proposed method can provide a
valuable tool for continuous health monitoring in emerging
applications of SiC devices to high reliability applications
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