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Variable-frequency drive

About: Variable-frequency drive is a research topic. Over the lifetime, 837 publications have been published within this topic receiving 5691 citations. The topic is also known as: VFD.


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Patent
Masoud Hajiaghajani1
09 Dec 2005
TL;DR: In this article, a method for producing hydrogen is provided that includes generating a product comprising hydrogen in a hydrogen generator, compressing the product in a compression unit having an induction motor and regulating the speed of the motor in response to transient operations of the hydrogen generator.
Abstract: An apparatus for producing hydrogen having compressor motor speed control. The apparatus includes a hydrogen generator for producing a product comprising hydrogen and a compression unit for compressing the product. The hydrogen generator can include a fuel processor having an oxidizer and a reformer. The compression unit has an induction motor and means for regulating the speed of the motor. The means for regulating the speed of the motor can include a variable frequency drive or soft start device having a plurality of switches and an adjustable ramp timer. A downstream unit including one or more of a purification unit, a second compression unit, and a storage unit is disposed downstream of the compression unit. A method for producing hydrogen is provided that includes generating a product comprising hydrogen in a hydrogen generator, compressing the product in a compression unit having an induction motor and regulating the speed of the motor in response to transient operations of the hydrogen generator.

10 citations

Patent
06 May 2020
TL;DR: In this paper, an electric driven hydraulic fracking system is described, which includes a single VFD, the single shaft electric motor, and the single hydraulic pump mounted on the single pump trailer.
Abstract: An electric driven hydraulic fracking system is disclosed. A pump configuration that includes the single VFD, the single shaft electric motor, and the single hydraulic pump that is mounted on the single pump trailer. A pump configuration includes a single VFD configuration, the single shaft electric motor, and the single shaft hydraulic pump mounted on the single pump trailer. The single VFD configuration converts the electric power at the power generation voltage level distributed from the power distribution trailer to a VFD voltage level and drives the single shaft electric motor to control the operation of the single shaft electric motor and the single hydraulic pump. The VFD voltage level is a voltage level that is required to drive the single shaft electric motor. The VFD configuration also controls operation of the auxiliary systems based on the electric power at the auxiliary voltage level.

10 citations

Dissertation
01 Jan 2015
TL;DR: MCSA has been improved to accurately detect electrical and mechanical faults in the induction motor namely broken rotor bars, stator faults and motor bearing faults, and a new method based on modulation signal bispectrum (MSB) analysis is introduced, which demonstrates that MSB-SE is an outstanding technique.
Abstract: Motor current signature analysis (MCSA) has been an effective method to monitor electrical machines for many years, predominantly because of its low instrumentation cost, remote implementation and comprehensive information contents. However, it has shortages of low accuracy and efficiency in resolving weak signals from incipient faults, such as detecting early stages of induction motor fault. In this thesis MCSA has been improved to accurately detect electrical and mechanical faults in the induction motor namely broken rotor bars, stator faults and motor bearing faults. Motor current signals corresponding to a healthy (baseline) and faulty condition on induction motor at different loads (zero, 25%, 50% and 75% of full load) were rearranged and the baseline current data were examined using conventional methods in frequency domain and referenced for comparison with new modulation signal bispectrum. Based on the fundamental modulation effect of the weak fault signatures, a new method based on modulation signal bispectrum (MSB) analysis is introduced to characterise the modulation and hence for accurate quantification of the signatures. This method is named as (MSB-SE). For broken rotor bar(BRB), the results show that MSB-SE suggested in this research outperforms conventional bispectrum CB significantly for all cases due its high performance of nonlinear modulation detection and random noise suppression, which demonstrates that MSB-SE is an outstanding technique whereas (CB) is inefficient for motor current signal analysis [1] . Moreover the new estimators produce more accurate results at zero, 25%, 50%, 75% of full load and under broken rotor bar, compared with power spectrum analysis. Especially it can easily separate the half BRB at a load as low as 25% from baseline where PS would not produce a correct separation. In case of stator faults, a MSB-SE is investigated to detect different severities of stator faults for both open and short circuit. It shows that MSB-SE has the capability to accurately estimate modulation degrees and suppress the random and non-modulation components. Test results show that MSB-SE has a better performance in differentiating spectrum amplitudes due to stator faults and hence produces better diagnosis performance, compared with that of power spectrum (PS). For motor bearing faults, tests were performed with three bearing conditions: baseline, outer race fault and inner race fault. Because the signals associated with faults produce small modulations to supply component and high noise levels, MSB-SE is used to detect and diagnose different motor bearing defects. The results show that bearing faults can induce detectable amplitude increases at its characteristic frequencies. MSB-SE peaks show a clear difference at these frequencies whereas the conventional power spectrum provides change evidences only at some of the frequencies. This shows that MSB has a better and reliable performance in detecting small changes from the faulty bearing for fault detection and diagnosis. In addition, the study also shows that current signals from motors with variable frequency drive controller have too much noise and it is unlikely to discriminate the small bearing fault component. This research also applies a mathematical model for the simulation of current signals under healthy and broken bars condition in order to further understand the characteristics of fault signature to ensure the methodologies used and accuracy achieved in the detection and diagnosis results. The results show that the frequency spectrum of current signal outputs from the model take the expected form with peaks at the sideband frequency and associated harmonics.

10 citations

Patent
24 Feb 2010
TL;DR: In this article, a hydraulic power device including a motor having a predetermined motor speed rating and motor power rating, at least one pump operably coupled to the motor, the pump being configured to provide, to the at least single load, a predetermined hydraulic fluid flow at a predetermined speed, and a variable frequency drive connected to a motor.
Abstract: A hydraulic power device for effecting operation of at least one load, the hydraulic power device including a motor having a predetermined motor speed rating and motor power rating, at least one pump operably coupled to the motor, the pump being configured to provide, to the at least one load, a predetermined hydraulic fluid flow at the predetermined motor speed rating, and a variable frequency drive connected to the motor, the variable frequency drive being configured to effect operation of the motor at a speed above the predetermined motor speed rating such that the at least one pump operates to provide an excess hydraulic fluid flow during operation of the motor substantially above the predetermined motor speed rating where the excess fluid flow is greater than the predetermined hydraulic fluid flow.

10 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20239
202220
202143
202084
201956
201887