1,721,009 research outputs found
Steady-State Performance Degradation of a DTC IM Drive Under Parameter Transduction Errors
No full textWith direct torque control (DTC), the stator flux
magnitude and the torque of an induction motor (IM) drive are
controlled in a closed-loop way. The actual values of the controlled
variables are estimated by processing the inverter dc-link voltage
and the stator currents by means of the IM voltage model. Any
error in the model parameter (the stator resistance) or in the
voltage and current transduction degrades the drive performance.
In this paper, a theoretical investigation of the effects of the various
errors on a DTC IM drive is carried out. The investigation gives
a proof of the drive instability due to some errors and provides,
for the other errors, the amount of the deviation produced on the
controlled variables in steady state. The theoretical findings are
substantiated by experimental and simulation results
A simple but high-performance IM speed drive
No full textThe paper deals with an induction motor (IM) speed drive having high performance
over a large speed range in the constant torque region. The drive is built up around an outer loop
of speed equipped with an incremental encoder and two inner loops of torque and flux
implemented in a direct torque control (DTC) scheme. The scheme takes advantage of the
available speed to estimate the motor torque and the stator flux magnitude by means of the IM
current model. This allows the full exploitation of the drive capabilities even in the low speed
range. Furthermore, with a suitable representation of the IM current model, the drive can be
operated down up to zero speed. The paper closes by analytically investigating the detuned
behaviour of the scheme due to a rotor time constant mismatch. Experimental results substantiate
the low-speed capabilities of the scheme and the findings on its detuned behaviour
All-Electric Ship Design: From Electrical Propulsion to Integrated Electrical and Electronic Power Systems
Full text linkElectrical propulsion is not a novel concept in marine systems. However, the availability of power electronic converters has proved to be the Key Enabling Technology for electrification of large ships. This paper starts with a summary of EP drives, which led to the birth of all-electric ships. Electric power generation and control systems are then presented, which make it possible to exploit the integrated electrical power system. To ease comprehension of the issues in designing such a system, its conventional design process is given. Then, the reasons that are pushing ahead the research in the shipboard power systems sector are discussed. The need for research in the design methods area is demonstrated through an overview of the latest results of technological research. Finally, a summary of the most significant results on the design tools research is given, including early stage design, dependable-oriented design, and the improvements achievable through software simulators and hardware-in-the-loop are discussed. The goal of this paper is to demonstrate why research on design methods is as important as a technological one, on the basis of the needs concerning the design, integration, and management of future 'integrated electrical and electronic power systems' (power systems with power conversion quota approaching 100%)
Dependability and functional safety with applications to industrial electronics
No full textIn this article, the two corpuses of dependability theory and functional safety standards are explicated with the purpose of providing a comprehensive treatment of them. It is shown how one corpus supplements the other with regard to safety. On this matter, dependability theory is limited to the enunciation of principles without paying attention to their practical implementation, while functional safety standards address the characteristics of the extra systems used to obtain a given safety level. This article closes with two case studies that exemplify the issues of dependability and functional safety for industrial electronics systems
Band-Constrained Technique for Direct Torque Control of Indusction Motor
No full textIn the paper, a novel technique for the direct torque
control (DTC) of an induction motor is proposed, which overcomes
the trouble of high torque ripple afflicting the conventional DTC
technique. With the novel technique, the inverter voltage vector
selected from the switching table is applied for the time interval
needed by the torque to reach the upper (or the lower) limit of the
band, where the time interval is calculated from a suitable modeling
of the torque dynamics. By this approach, the control system
emulates the operation of a torque hysteresis controller of analog
type since the application time of the inverter voltage vector is dictated
by the allowed torque excursion and not by the sampling period.
It is shown by experimental results that the technique yields a
considerable reduction of the torque ripple. A further and ultimate
reduction is obtained by compensating for the delay inherent in the
discrete-time operation of the control system. The outcome is that
the torque ripple of the motor is constrained within the hysteresis
band of the torque controller, for a band of customary value. An
ancillary merit of the technique is the almost full elimination of the
average torque error inherent in the conventional technique. If the
hysteresis band is shrunk, the torque ripple is bound to swing out
the band limits. Under this circumstance, an extension of the technique
is developed, which helps keep the torque ripple at minimum.
To assess the characteristics of the proposed DTC technique, the
following quantities: average torque error, rms value of the torque
ripple, and inverter switching frequency are measured for different
stator flux angular speeds and hysteresis bands of the torque and
flux controllers. As a comparison, the same quantities are given for
the conventional DTC technique
Transient simulation on power network including deep-bar induction motors and series capacitors
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