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ABSTRACT: The influences of PWM switching and long cable length on motor insulations have been discussed in numerous papers. This paper investigates their effect on the voltage insulation components inside an adjustable speed drive (ASD). This paper shows that high potential voltage insulation issue may exist on various components inside the ASD and cause earlier failures under very long cable or multiple drive conditions. A system model to describe this phenomenon is described in the paper. A dc bus voltage clamp circuit is proposed to reduce these voltage stresses. The effectiveness of this circuit is verified by both simulation and experimental results.
IEEE Transactions on Industry Applications 09/2011; · 1.66 Impact Factor
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ABSTRACT: The influences of PWM switching and long cable length on motor insulations have been discussed in numerous papers. This paper investigates their effect on the voltage insulation components inside an Adjustable Speed Drive (ASD). This paper shows that high potential voltage insulation issue may exist on various components inside the ASD and cause earlier failures under very long cable or multiple drive conditions. A system model to describe this phenomenon is described in the paper. A DC bus voltage clamp circuit is proposed to reduce these voltage stresses. The effectiveness of this circuit is verified by both simulation and experimental results.
Energy Conversion Congress and Exposition (ECCE), 2010 IEEE; 10/2010
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ABSTRACT: PWM AC drives generate high differential mode motor voltages due to the reflected wave phenomenon. The common-mode voltage produced by a PWM inverter also has fast transitions that result in high peak currents to ground. For low power AC drives this can present several issues, such as pump-up of the DC bus and failure of the power module due to high instantaneous currents that are often undetected because of the typical sampling algorithm used. In this paper, existing drive output filter solutions are reviewed and a new filter design is presented, which has integrated differential-mode and common-mode impedance with damping matched to typical cable surge impedance. This eliminates reflections of both differential-mode and common-mode traveling waves, and also reduces peak cable charging currents. Experimental results are provided to demonstrate that the new filter has improved performance to reduce motor differential-mode and common-mode voltage, and drive output common-mode current, thus mitigating the issues specifically seen with low power AC drives. Complete design details for the filter and a particular implementation of the integrated differential-mode and common-mode reactor are also presented.
Energy Conversion Congress and Exposition (ECCE), 2010 IEEE; 10/2010
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ABSTRACT: A failure mode for pulsewidth-modulation inverter-fed ac motors due to the antiresonance phenomenon is introduced and investigated in this paper. At high frequencies, an ac motor behaves as a series RLC circuit with a resonance point, so-called antiresonance, typically above 1.0 MHz. If the voltage oscillation frequency caused by the reflected-wave phenomenon matches the motor antiresonance frequency, an amplified voltage will appear internally between the turns of the stator windings. This externally unobservable state can cause winding insulation failure in the ac motor. This phenomenon is experimentally verified using a rewound permanent-magnet motor with accessible taps along the stator windings, and the results are presented in this paper.
IEEE Transactions on Industry Applications 11/2009; · 1.66 Impact Factor
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ABSTRACT: A systematic procedure to determine the parameters of a previously proposed low- to high-frequency induction motor model is presented. An analysis of the high-frequency behavior with regard to the impact of magnetic core selection, parasitic interturn and winding-to-frame capacitors, and skin effects of windings is investigated in greater detail for the proposed universal model of an induction motor. The model is universal in the sense that it is derived by extending the low-frequency standard T-equivalent circuit (IEEE Standard 112) to include high-frequency effects under both common- and differential-mode domains and can be used for transient reflected-wave studies and electromagnetic interference emissions in motor drive systems. A test-based method and an analytical approach, which are useful in application and design stages, respectively, are presented to determine the frequency characteristics of the induction motor. Findings of the investigation were verified experimentally with results presented in this paper.
IEEE Transactions on Industry Applications 03/2009; · 1.66 Impact Factor
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ABSTRACT: A systematic procedure to determine the parameters of a previously proposed low-to-high frequency induction motor model is presented. Analysis of the high-frequency behavior with regard to the impact of magnetic core selection, parasitic inter-turn and winding-to-frame capacitors, and skin effects of windings is investigated in greater detail for the proposed universal model of an induction motor. The model is universal in the sense that it is derived by extending the low frequency standard-T-equivalent circuit (IEEE Std. 112) to include high- frequency effects under both common-mode and differential- mode domains, and can be used for transient reflected wave studies and EMI emissions in motor drive systems. A test-based method and an analytical approach, respectively useful in application and design stages, is presented to determine the frequency characteristics of the induction motor. Findings of the investigation were verified experimentally with results presented in this paper.
Industry Applications Conference, 2007. 42nd IAS Annual Meeting. Conference Record of the 2007 IEEE; 10/2007
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ABSTRACT: A three-phase induction motor model that depicts the motor behavior over a wide range of frequencies from 10 Hz to 10 MHz is presented in this paper. The model is universal in the sense that common-mode, differential-mode, and bearing circuit models are combined into one three-phase equivalent circuit model. The proposed model is basically an extension of the low-frequency IEEE Standard 112 circuit model. The proposed model was experimentally simulated and verified with results presented.
IEEE Transactions on Industry Applications 10/2007; · 1.66 Impact Factor
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ABSTRACT: Multipulse rectifier system has been shown to be a cost-effective harmonic solution in many industries where IEEE 519 is specified. However, it is susceptible to poor quality of the input source of the power distribution system where the phase unbalance of the source voltage and preexisting low-order harmonic voltages are presented. A small amount of voltage unbalance with preexisting harmonics can create large amount of current harmonics to the input source. Consequently, a stricter preexisting voltage total harmonic distortion condition has to be specified for an 18-pulse rectifier to meet the IEEE 519 current-harmonics requirement. This paper introduces a dc link passive filtering method to solve this problem. It greatly reduces the current harmonics created by the phase unbalance, the fifth-, and the seventh-order voltage harmonics by adding several series LC resonant loops into the dc link. As a result, the proposed 18-pulse rectifier can meet IEEE 519 under several abnormal source voltage conditions of the ac line. Theory analysis, simulation, and experimental result are provided in this paper to verify the effectiveness of this method
IEEE Transactions on Industry Applications 06/2007; · 1.66 Impact Factor
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ABSTRACT: More and more AC drive installations are requiring manufacturer's to improve line side harmonics to ultimately meet IEEE Harmonic Std 519-1992 on site. This paper reveals several patented transformer topologies for such an effort. Compared with other harmonic solutions, auto and isolated transformers possess advantages as being simple, reliable, minimal line resonance problems and relatively cost effective. The proposed nine and twelve-phase auto-transformers can be viewed as a polygon winding type, where besides achieving an improved input current harmonics, junction points among various windings along the polygon can be wired out for step-down, unity and step-up voltage transfers. When electrically isolated primary windings are added, unlimited transfer ratio is available for every application. Application of these new industrial transformer devices, along with simple power diode energy conversion methods, result in a robust and reliable system that provides good DC bus regulation for AC drives utilizing a common DC bus configuration. The proposed topologies also provide a high AC input power factor and minimize harmonic currents to the utility interface. The paper provides technical analysis and field site data on the new topologies, as well as per unit metric comparison to other harmonic mitigation techniques versus horsepower size.
Industry Applications Conference, 2003. 38th IAS Annual Meeting. Conference Record of the; 11/2003
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ABSTRACT: Finite elements are used to predict losses and temperatures of two different inductors used in AC drives. One inductor has a core made of thin steel laminations, while the other is made with a new soft magnetic composite core material. First, electromagnetic finite element software is used to compute parameters including inductance, core loss, copper loss, and power loss for various current amplitudes and frequencies ranging from 1 Hz to 200 kHz. The core losses are computed using lamination loss and Steinmetz formulas. Finally, thermal finite element software is used to compute typical temperature distributions, which are found to agree reasonably well with measurements on both inductors.
Electric Machines and Drives Conference, 2003. IEMDC'03. IEEE International; 07/2003
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G.L. Skibinski
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ABSTRACT: Modern industry installations using power electronic conversion systems are requiring improvements in the loadside output voltage waveshape to meet demands of various operating load conditions. This paper reveals a novel series resonant sinewave output filter apparatus inserted between a pulse width modulated (PWM) voltage source inverter (VSI) and passive load or dynamic motor load. Compared with conventional LC low pass filters, the topology given gives size, weight, fast circuit dynamic response advantages and is relatively cost effective. A description of circuit operation, mathematical analysis, analytical results and experimental results is given. The power electronic component work done to push the polypropylene filter capacitors to new high frequency current limits, as well as pushing a new low loss high-frequency pot core inductor material to new current and thermal constraint limits, is highlighted.
Industry Applications Conference, 2002. 37th IAS Annual Meeting. Conference Record of the; 02/2002
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ABSTRACT: Trend prediction for power electronic industry among researchers is more silicon and less passive components. AC-AC matrix converter is an excellent example for such trend. However, as an equipment manufacturer, we are more interested in competitiveness of cost and size. As our investigation turns out, AC-AC matrix converter has all merits of both worlds, more silicon, less passive component values, more cost and bigger size. Therefore, the statement "more silicon and less passive components will certainly result in cost and size reduction" may not be true for all time.
Industry Applications Conference, 2002. 37th IAS Annual Meeting. Conference Record of the; 02/2002
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ABSTRACT: The petroleum and chemical industry has found increasing favor
with 60 Hz low-voltage (⩽600 Vac) power systems that utilize a
high-resistance grounded (HRG) neutral philosophy. Historically, the
older generation of adjustable-speed drives (ASDs) had little or no
effect on the normal operation of ground-fault indicators (GFIs) used
with the installed HRG systems. This paper focuses on nuisance GFI
alarms that may occur when present-generation ASDs are retrofitted into
the existing plant. The paper first reviews possible neutral grounding
systems, with emphasis on the types of HRG systems possible and GFI
alarm philosophy. The paper then discusses how ASDs may generate
zero-sequence high-frequency noise currents in the HRG neutral circuit,
which may cause nuisance ground-fault alarms and potentially mask a
legitimate ground fault. GFI noise current magnitude is defined for both
present and older ASD technologies. The effect this transient
zero-sequence noise current magnitude has on GFI operation is described.
Mitigation methods used at the drive to reduce ASD noise current
magnitude to acceptable nonalarm levels is investigated. Filter
solutions located at the HRG/GFI meter that reduce nuisance alarms are
also investigated. The pros and cons of at the drive or at the meter
filter solutions are supported with laboratory and field test data.
Application guidelines are given to help avoid nuisance problems with a
plant ground-fault protection scheme, which needs to successfully
operate in the presence of multiple ASDs
IEEE Transactions on Industry Applications 10/2001; · 1.66 Impact Factor
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ABSTRACT: Motor bearing life historically has been difficult to predict.
Many variables influence bearing life in motors, including operating
speed, mechanical fit, loading, lubrication, vibration, and
environmental conditions. A large synthetic fibers producer discovered
that motor shaft voltage induced by variable-frequency drives (VFDs) can
add another significant variable to the formula. Based upon this
experience, this paper presents theory, test data, and actual results
quantifying electrical discharge machining damage to bearings initiated
by VFDs. The paper presents several mitigation techniques and quantify
their relative effectiveness and attributes. Other factors and
interactions of the above-mentioned variables are also discussed in
relation to the total goal of improving motor bearing life
IEEE Transactions on Industry Applications 10/2001; · 1.66 Impact Factor
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ABSTRACT: Reflected-wave transient voltages that result from fast insulated
gate bipolar transistor (IGBT) voltage-source inverters have received
considerable investigation. The modeling and simulation of these
transients require sophisticated motor and cable models. Most
voltage-source pulsewidth modulated (PWM) adjustable-speed drive
suppliers now provide combinations of passive and active control
techniques to mitigate the adverse effects of overvoltage stress,
however, the costs of the passive fixes often exceed the cost of the
drive. Another aspect of low-rise-time devices, heretofore not examined
to the extent of the overvoltage problem, is the resulting current from
traveling waves. In this paper, a historical perspective of the
overvoltage problem is presented. Models of system components are
reviewed, and simulation results are compared with experimental results.
These models are then employed to predict the peak currents from
voltage-source inverters as the cable, load, and IGBT rise time are
altered. The paper will then examine the consequences of reflected wave
currents on current sensing, drive control and device performance. From
these results, a minimum rise time is established
IEEE Transactions on Industry Applications 12/1999; · 1.66 Impact Factor
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ABSTRACT: Electromagnetic interference (EMI) noise is defined as an unwanted
electrical signal that produces undesirable effects in a control system,
such as communication errors, degraded equipment performance and
malfunction or nonoperation. This article provides a common
understanding of the EMI issues and provides simple pre-installation and
post-installation guidelines useful for all interested parries involved
in the industry application of adjustable speed PWM invertor-fed AC
motor drives
IEEE Industry Applications Magazine 12/1999; · 0.64 Impact Factor
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ABSTRACT: The unprecedented growth in industrial motor drives over the past
decade resulted from the process improvements demanded by the automation
industry. With the increased speed of modern micro-controllers and
digital signal processors and the reduced insulated gate bipolar
transistor (IGBT) drive package size, coupled with the low maintenance
of AC motors, multiple machine configurability has been achieved with
minimal process downtime. This progress required significant effort in
mitigating numerous technical problems associated with this rapidly
expanding technology. The paper reviews the economic trends in the
industry, performance enhancements for volts per hertz (V/F) drives and
high performance field oriented controllers (FOC), inverter hardware
topologies, and IGBT induced system problems and solutions. Finally, the
authors look beyond the year 2000 (Y2K) and offer a glimpse at what is
possible and practical over the next five years
Applied Power Electronics Conference and Exposition, 1999. APEC '99. Fourteenth Annual; 04/1999
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ABSTRACT: This paper describes an alternative solution for cables used with
insulated gate bipolar transistor (IGBT) variable frequency drives
(VFDs). New IGBT technology has introduced voltage stresses on motors
and cables that lead to unpredictable system performance and
reliability. This paper includes a performance and cost comparison
between a continuously welded armored option, the option of lead wire in
conduit and a proposed shielded tray cable. Unique physical
characteristics of the cables are discussed. A proposed cable with
increased insulation thickness is discussed that insures long-term cable
service life under VFD operation, while the shielded coaxial braid
contains VFD EMI emissions. Other applications, options, and termination
considerations with respect to the petrochemical industry are discussed.
Cable performance is documented with theoretical and experimental
support
Petroleum and Chemical Industry Conference, 1999. Industry Applications Society 46th Annual; 02/1999
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ABSTRACT: This paper investigates the repetitive surge-voltage withstand of
low-voltage mush-wound machines operated on adjustable-speed drives
(ASDs) using insulated gate bipolar transistor (IGBT) semiconductor
technology. Historical work on surge testing of motor insulation has
focused on one or more of the following aspects: (1) large horsepower
motors; (2) medium-voltage form-wound motors; (3) single-shot
impulse-type transients; or (4) low-voltage machines with surge
risetimes >200 ns. IGBT drives can have risetimes of 50-200 ns. Thus,
a new study on electrical stress of insulation systems due to the
nonlinear voltage distribution of mush-wound motors when subjected to
repetitive steep dV/dt square-pulse waveforms (rather than impulse wave
testing) is presented. Magnitude and risetime of the repetitive ASD
surge-voltage transient induced on the machine terminals is reviewed
first. Next, surge propagation into the winding was investigated to
identify maximum voltage stress points on the conductor insulation.
Potential failure mechanisms observed at these points are then
discussed. The significance of decreasing surge risetime and increasing
cable lengths on internal nonlinear voltage distribution is studied with
experimental results from a 7.5-hp motor with a tapped stator winding
IEEE Transactions on Industry Applications 08/1998; · 1.66 Impact Factor
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ABSTRACT: This paper evaluates a new induction motor, the electrostatic
shielded induction motor (ESIM). An ESIM reduces rotor shaft voltages to
levels below the bearing lubricant's electric field intensity breakdown
level and offers one solution to accelerated bearing wear caused by
fluting induced by pulsewidth modulated (PWM) inverters. The paper
begins by reviewing shaft voltages and the resulting bearing currents
when operated on PWM voltage source inverters. An example of bearing
fluting is shown, and system models are presented and discussed. The
construction details and test results for several ESIMs are presented.
Experimental results show the ESIM solves the electrostatically induced
rotor shaft voltage and bearing problem without degrading the
electromagnetic performance of the motor
IEEE Transactions on Industry Applications 12/1997; · 1.66 Impact Factor
