Variable Frequency Drive Systems

Blair, Thomas Howard

doi:10.1002/9781119238041.ch18

Cited by 6 publications

(4 citation statements)

References 3 publications

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“…On the other hand, variable frequency drives (VFDs) convert a fixed voltage and frequency input into a variable voltage and frequency output using power electronics. The most common VFD, the PWM-type, improves stable voltage and frequency outputs and eliminates cogging in motors [15]. A constant voltage-to-frequency (volts-per-hertz) ratio leads to a fixed flux.…”

Section: Selection Of Motor-starting Methods For Canned Motor Rcpmentioning

confidence: 99%

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Acceleration Analysis of Canned Motors for SMR Coolant Pumps

2023

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An SMR (small modular reactor) is expected to be able to operate flexibly in conjunction with a high renewable energy penetration grid as a result of improved safety and easy power control compared to large nuclear power plants. SMRs, such as South Korea’s System-integrated Modular Advanced ReacTor (SMART), are designed to use canned motors (CMs) for their reactor coolant pumps (RCPs) to enhance their safety. CMs passively enhance the reactor’s safety by preventing the leakage of radioactive reactor coolant. However, with motor sizes designed to be as small as possible, and the increased air gap of CMs between the stator and rotor, the starting torque may be insufficiently low compared to that of similar-sized induction motors (IMs). Thus, CMs may require variable frequency drives (VFDs) to start. This paper compares the torque characteristics of CMs with those of IMs for SMART’s RCPs. ETAP is then used to perform a motor-starting analysis for CMs activated with and without VFDs. The results are presented and analyzed to find out if VFDs can deal with the CM starting torque issue.

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Section: Selection Of Motor-starting Methods For Canned Motor Rcpmentioning

confidence: 99%

“…However, introducing a VFD start as a motor driving method also introduced challenges [15,18,19]. Electromagnetic emissions can be produced from the VFD's output terminal and cause an interference.…”

Section: Selection Of Motor-starting Methods For Canned Motor Rcpmentioning

confidence: 99%

Acceleration Analysis of Canned Motors for SMR Coolant Pumps

2023

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“…The most common type of VFDs used in industry, and the type used at this research site, are pulse width modulated (PWM) inverter-type VFDs. This type of VFD is composed of three main components: a rectifier, a DC bus, and an inverter (Kaiser et al, 2008;Blair, 2017). The rectifier is used to convert AC power to DC power.…”

mentioning

confidence: 99%

“…Then, this DC power is run through a DC bus containing a capacitor that filters and smooths the signal. Finally, the smoothed DC signal goes through the inverter to convert the signal to a three-phase AC power supply, generally through a series of transistors (Kilowatt Classroom, 2003;Kaiser et al, 2008;Blair, 2017).…”

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confidence: 99%

Flow Rate and Volume Estimates from Variable Frequency Drive Operated Drainage Sump Pumps

Nelson,

Scherer,

Jia

2024

Applied Engineering in Agriculture

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Highlights This article provides an overview of operations and benefits of using a variable frequency drive to operate agricultural subsurface drainage system sump pumps. A methodology is proposed to monitor flow rates leaving agricultural subsurface drainage pump stations via a MATLAB algorithm. The results of this research were mixed because the algorithm estimates did not always match with the corresponding flowmeter measurements. Abstract. Subsurface drainage plays a crucial role in excess water removal through perforated pipes buried in the soil. The Red River Valley of eastern North Dakota and west central Minnesota often requires pumped drainage outlets due to its flat topography, with many modern systems incorporating variable frequency drives (VFD) for improved efficiency. VFDs adjust pump speeds to match drainage needs, but this dynamic operation complicates accurate flow rate estimation for edge-of-field monitoring. This project aimed to devise an automated method for calculating flow rate estimates from VFD pumping systems involving tank geometry, operational water levels, and pump duty cycling. Linear regressions with calibration data from a transit-time ultrasonic flowmeter produced mixed outcomes. Some linear regressions revealed errors in calculated versus measured flow rate of =14%, while other regressions showed errors nearing 40%. To address this, future efforts should explore methods incorporating the pump’s electrical characteristics. This approach would provide a more accurate representation of the unstable and intricate pumping operations during transient conditions. Keywords: Edge-of-field monitoring, Flow rate, Pump, Red River Basin, Subsurface drainage, Variable frequency drive

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Smooth frequency change effects in electrical circuits: explained by the Fresnel integral

Wach

2022

SN Appl. Sci.

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The paper presents the problem of the relation between ac voltage frequency supplying a circuit and the resulting current frequency in that circuit in the case when the voltage frequency changes smoothly following a $${f}_{{v}}\left(t\right)$$ f v t function. Contrary to the expectations, the resulting current frequency fc(t) changes in a different way that this of the voltage. One can say that the current frequency variations are considerably amplified compared with these of the supply voltage. This problem is important because we have to deal with voltage frequency changes that are introduced deliberately, like in case of starting ac motors, and voltage frequency variations that result from external influences, like in case of electrical grids with significant component from wind generating units. Paper solves this problem in analytical way by presenting a relation between supply voltage frequency variations $${f}_{v}\left(t\right)$$ f v t and resulting current frequency fc(t). It also contains solution of the inverse problem which can find the frequency function of the supply voltage that will result in a required frequency of the current. According to the best author’s knowledge, this problem was not reported and examined before and potentially has a number of practical implications, one of which – the induction motor frequency starting – is presented as for example purposes in the paper. The significance of the problem discussed in this paper has still to be examined and established, since frequency variations apply to many engineering branches and until now were counteracted by frequency control without a comprehensive identification of the problem.Article Highlights The supply voltage frequency variations have an important effect on the respective current frequency of the loads. One can forecast that a frequency of the current changes so that it follows exactly the frequency change of the supply voltage. However, in reality the situation looks much different. The frequency of the current changes occur much more intensively than the frequency in the supply voltage, that is the frequency changes of the current amplify the variations of the supply voltage. This phenomenon has neither been examined nor described in technological literature yet, according to best author’s knowledge. The paper presents, explains and solves the problem in an analytical way. It presents a formula to calculate the frequency of a current when a function of the frequency of the supply voltage is given. The paper also contains a solution of the inverse of the problem described above. There is presented general form of an ordinary differential equation that serves to find a supply voltage frequency function which results in required frequency of the current in a circuit. Presented solutions are general and hold for any lumped parameters circuits: single phase, multi-phase as well as for ac electrical motors supply. In the paper this is demonstrated for single phase circuit supplied by the three exemplary voltage frequency functions as well as for the case of induction motor frequency starting.

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Variable Frequency Drive Systems

Cited by 6 publications

References 3 publications

Acceleration Analysis of Canned Motors for SMR Coolant Pumps

Acceleration Analysis of Canned Motors for SMR Coolant Pumps

Flow Rate and Volume Estimates from Variable Frequency Drive Operated Drainage Sump Pumps

Smooth frequency change effects in electrical circuits: explained by the Fresnel integral

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