• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.1
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• pp.81-87
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• 2004

This paper describes a design method of electromagnetic interference (EMI) filter for pulse-width modulation (PWM) inverter-fed AC drives used for home appliances such as washing machine and air conditioner. The generating and coupling mechanisms of the conducted EMI for AC drives are first investigated. The design procedure of the EMI filter based on the EMI separation principle is then presented. Experiments we carried out for the PWM inverter-fed induction motor drive system and it is shown that the results satisfy the EN55014 EMI regulation.

• Journal of Power Electronics
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• v.15 no.2
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• pp.411-418
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• 2015

In this paper, a new method for the online estimation of equivalent series resistances (ESR) of the DC-link capacitors in induction machine (IM) drive systems with a front-end diode rectifier is proposed, where the ESR estimation is conducted during the regenerative operating mode of the induction machine. In the first place, a regulated AC current component is injected into the q-axis current component of the induction machine, which induces the current and voltage ripple components in the DC-link. By processing these AC signals through digital filters, the ESR can be estimated by a recursive least squares (RLS) algorithm. To acquire the AC voltage across the ESR, the DC-link voltage needs to be measured at a double sampling frequency. In addition, the ESR current is simply reconstructed from the stator currents and switching states of the inverter. Experimental results have shown that the estimation error of the ESR is about 1.2%, which is quite acceptable for condition monitoring of the capacitor.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.337-342
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• 2005

Direct torque control (DTC) was originally developed for induction machine drives, and, more recently has been applied to permanent magnet brushless AC (BLAC) drives. In this paper, the performance of DTC controlled brushless DC (BLDC) drives is compared with that of PWM current controlled BLDC drives, both with and without current shaping. Both simulation and experimental results are presented, as well as the analysis of the resulting torque waveforms. It is shown that, in addition to exhibiting a fast torque response, a DTC controlled BLDC drive has a significantly lower low-frequency torque ripple than the PWM current controlled BLDC drive without current shaping, and that it is easier to implement than PWM current control with current shaping.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.9
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• pp.928-933
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• 1990

In the vector controlled induction machine drives, mechanical speed sensors such as shaft encoder and resolver have been used. However, the mechanical speed sensors present some problems and restrict the wide applications of high performance AC drives. This paper describes the vector strategy with the speed estimation algorithm in which motor slip frequency is calculated. Also, the angle deviation of the rotor flux vector is calculated and instantaneously compensated to keep the q axis flux zero in the rotational reference frame.

• Journal of Power Electronics
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• v.16 no.1
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• pp.142-152
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• 2016

Common mode voltage (CMV) generation is a major problem in switching power converter fed induction motor drive systems. CMV is the zero sequence voltage generated due to the switching action of power converters. Even a small magnitude of CMV with a high rate of change may circulate large bearing currents which may damage a machine's bearings and shorten its life. There are several methods of controlling CMV. This paper presents 3-level sinusoidal pulse width modulation based techniques to control the magnitude and rate of change of CMV in multilevel AC-DC-AC drive systems. Simulation and experimental investigations have been presented to validate the performance of proposed technique to control CMV in 3-level neutral point clamped inverter based AC-DC-AC system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.8
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• pp.475-481
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• 2002

In this paper the new converter topology using single-Phase full bridge inverter for the switched reluctance motor drives is proposed. The proposed SRM drives are supplied by the AC pulse voltage source, while the conventional drives are supplied by the DC voltage source. Speed of the SRM is controlled by adjusting the frequency and the multitude of output current of inverter. The SRM using the proposed converter reduces the switching loss and the machine core loss, and has ability to pre-regulate the input voltage. The total number of power switches become fewer than another topology as a number of stator poles becomes more. Power circuit of an inverter is simpler and its volume is smaller because the module device involving several switches is used as an inverter.

• Journal of Power Electronics
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• v.2 no.4
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• pp.231-239
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• 2002

This paper describes the restructuring of power electronics and electric drives courses, sponsored by NSF, EPRI, NASA and the local utilities, which has significantly increased student enthusiasm, and the undergraduate enrollment in these courses at the University of Minnesota has tripled since 1997. The developed leaching approaches have been the subject of NSF-sponsored faculty workshops in 1994, 1997, 1998,2002, and 2003. In power electronics, the power-pole based building-block approach unifies analysis and control aspects of all converters. PSpice-based simulations aid in analysis and design, supported by a hardware laboratory. For electric drives, an integrative approach addressing all three aspects of electric drives - machines, power converters and control is being. used. Space vectors, introduced on a physical basis rather than purely mathematical ions, are used fur analysis of ac machines. This leads to a more physical understanding of machine operation and also makes it easier to address control aspects in the advanced course. The lecture materials are supported by a DSP-based laboratory.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.161-165
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• 1997

For high performance ac drives, the speed sensorless vector control and the stator flux orientation concept have received increasing attention. This paper presents a new method of estimation the speed of AC induction machine(IM). To improve the speed estimation characteristics, accurate stator resistance variation is considered. The effectiveness of the proposed method is verified computer simulation.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1012-1024
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• 2016

This study deals with an on-line software fault detection, localization, and system reconfiguration method for electrical system drives composed of three-phase AC/DC/AC converters and three-phase permanent magnet synchronous machine (PMSM) drives. Current sensor failure (outage), speed/position sensor loss (disconnection), and damaged DC-link voltage sensor are considered faults. The occurrence of these faults in PMSM drive systems degrades system performance and affects the safety, maintenance, and service continuity of the electrical system drives. The proposed method is based on the monitoring signals of "abc" currents, DC-link voltage, and rotor speed/position using a measurement chain. The listed signals are analyzed and evaluated with the generated residuals and threshold values obtained from a Sliding Mode Current-Speed-DC-link Voltage Observer (SMCSVO) to acquire an on-line fault decision. The novelty of the method is the faults diagnosis algorithm that combines the use of SMCSVO and adaptive thresholds; thus, the number of false alarms is reduced, and the reliability and robustness of the fault detection system are guaranteed. Furthermore, the proposed algorithm's performance is experimentally analyzed and tested in real time using a dSPACE DS 1104 digital signal processor board.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1495-1502
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• 2017

The Theory of operation of switched reluctance motors (SRM) depends on the reluctance torque, where energy is transferred to stator winding only. Although its construction is simple, the electrical design is complex, due to the switching configuration needed to deliver power to stator coils. However, because of the nonlinearly of magnetic circuit, SRM has torque ripple. This paper proposes a new strategy to drive SRM from a single-phase AC supply. Each stator winding is connected to AC-DC or AC-AC converters, which is called branch. All branches are connected in parallel to a single-phase AC supply. A shaft encoder allows current production in stator winding during the positive torque production region and terminates it during the negative torque production region. A magnetic flux is produced between stator poles when current is supplied from AC supply to stator coil and repeats many cycles as long as the rate of change of stator inductance is positive. Different possibilities for the configurations of AC-AC or AC-DC converters are introduced to drive SRM from the single-phase AC supply. A case study is presented for a SRM fed from AC supply through semi-controlled AC-DC converter is presented. A simulation model is introduced and verified by experimental rig for two-phase SRM.