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Showing papers on "Variable-frequency drive published in 2017"


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a gear pump for very low power output applications (1-10 kW gross power production), where the losses are volumetric, mechanical and also electrical of motor and variable frequency drive.

28 citations


Journal ArticleDOI
TL;DR: The main contribution of this paper is a methodology for the estimation of the energy savings that can be achieved from the use of such an energy recovery feature and the optimum braking duration that maximizes the recovered energy.
Abstract: Motor drives is a widely used technology, offering many advantages, such as exceptional speed control and flexibility. Improvement of reliability and efficiency has become a great research interest. Toward this direction and considering the major recent developments in supercapacitor technology, the use of bidirectional energy recovery converters has been introduced in various industrial applications. In this paper, the regenerative braking of a three-phase induction motor controlled by a variable frequency drive will be analyzed and the portion of kinetic energy that can be recovered will be calculated. The main contribution of this paper is a methodology for the estimation of the energy savings that can be achieved from the use of such an energy recovery feature. In addition, the optimum braking duration that maximizes the recovered energy will be investigated. The analysis presented in this paper has been validated experimentally and the results are discussed.

21 citations


Journal ArticleDOI
TL;DR: The efficiency of the pumping system is identified by incorporating the efficiency of both motor and the variable frequency drive (VFD) in real time simulated variable speed multi pumping system.

21 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a new dv/dt filter suitable for use with high power ac motors at distances nearing 300m with a built-in resistor failure detection circuit.
Abstract: Insulated gate bipolar transistors (IGBTs) will soon be replaced by wide band gap devices (SiC and GaN) as the choice for power semiconductor switch in voltage source inverters. These devices have extremely fast rise time and fall time compared with IGBT devices. The high dv/dt of pulse-width modulation outputs create excessive voltage stress in the insulation system of ac motors due to voltage reflection issues associated with motors at large distances from the drive. In many oil field applications, the distance between the motor and the variable frequency drive approaches 300 m. In walking rig applications, it is common to use multiple smaller sized conductors per phase, bunched together, to achieve the desired ampacity. This practice results in higher than usual value of the cable parasitic capacitance. Traditional dv/dt filters used for mitigating over-voltage at motor terminals have been found to be inadequate in reducing the over voltage at the motor terminals in such oil field installations. The damping resistor often experiences high voltage and gets damaged. A new dv/dt filter suitable for use with high power ac motors at distances nearing 300 m with a built-in resistor failure detection circuit is proposed here. Test results are given to demonstrate its efficacy.

19 citations


Proceedings ArticleDOI
01 Mar 2017
TL;DR: In this paper, a carrier-based three-level PWM is proposed to improve the flying capacitor voltage balancing in the NNPC converter, which can guarantee enough redundant switching states for voltage balancing during the whole fundamental period without changing the voltage-second product.
Abstract: Nested Neutral-Point-Clamped (NNPC) converter is a newly proposed 4-level converter It has advantages similar to other multilevel converters but has disadvantages caused by the difficulties in balancing the voltages on its flying capacitors This will limit its application in Variable Frequency Drive (VFD) system — an important application area for multilevel converters In order to improve the flying capacitor voltage balancing, a carrier based three-level PWM is proposed This method can guarantee enough redundant switching states for voltage balancing during the whole fundamental period without changing the voltage-second product The output quality under low-frequency operation will be improved significantly due to the improvement in voltage balancing brought by this method It also features simple and easy implementation compared to space vector based approach

11 citations


Proceedings ArticleDOI
TL;DR: In this paper, the authors describe efficiency measurement in induction motor and variable-frequency drives systems under imposed voltage unbalance at the drive input, and highlight differences in the effect of voltage imbalance on drive performance.
Abstract: This paper describes efficiency measurement in induction motor and variable-frequency drives systems under imposed voltage unbalance at the drive input. A number of drives from different manufacturers are tested with matching sizes of motors and the results are compared. The results highlight differences in the effect of voltage unbalance on drive performance. The results also indicate that intrinsic motor performance has important influence on motor-drive system efficiency.

11 citations


Proceedings ArticleDOI
01 Oct 2017
TL;DR: In this article, a hypothetic silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) power module for the medium voltage (MV) variable frequency drive (VFD) was proposed.
Abstract: This paper proposes a hypothetic silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) power module for the medium voltage (MV) variable frequency drive (VFD). A peer-to-peer comparison between commercial silicon (Si) insulated-gate bipolar transistor (IGBT) and the proposed SiC MOSFET module results in some promising results to support the introduction of SiC power modules for the MV VFD market.

9 citations


Proceedings ArticleDOI
26 Mar 2017
TL;DR: In this paper, a high-efficiency, high-speed variable frequency drive (VFD) was used in an electrically-assisted turbocharging application with the goal of reducing turbo lag and extracting electrical energy during vehicle braking and deceleration events.
Abstract: This paper presents a high-efficiency, high-speed variable frequency drive (VFD) used in an electrically-assisted turbocharging application with the goal of reducing turbo lag and extracting electrical energy during vehicle braking and deceleration events To maximize switching frequency and achieve high-temperature operation, SiC MOSFETs are used in lieu of Si IGBTs or MOSFETs Furthermore, the VFD is cooled using the existing engine coolant loop, which operates near 105 deg C Eliminating the need for an additional 65 deg C liquid cooling loop, which are typical of electric vehicles, significantly reducing system complexity, volume, and weight and simplifying integration A digital sliding-mode-observer (SMO) was developed to drive the machine at a ramp rate of over 68 kRPM/sec A dead-time compensation algorithm based upon adaptive notch filters was used to eliminate low-order current harmonics, which can degrade the sensorless control algorithm's performance Experimental results are presented confirming the VFD's efficiency, dynamic control performance, low-THD load current, and high-temperature operation Lastly, using a previously developed electro-thermal model, the VFD is extended to higher voltage (450 V ac ) motors for application in future vehicle traction drives The results show that the presented drive exceeds the Department of Energy's targets for traction drives in 2020

7 citations


Proceedings ArticleDOI
01 Oct 2017
TL;DR: The implementation of a system capable of emulating the production curve of a wind turbine using a DC machine consisting of an asynchronous machine-ASM controlled by a variable frequency drive which receives the speed set point from a computer.
Abstract: This work presents the implementation of a system capable of emulating the production curve of a wind turbine using a DC machine. The system consists of an asynchronous machine-ASM controlled by a variable frequency drive which receives the speed set point from a computer. This ASM was mechanically coupled to a DC generator. A DC/DC power converter was implemented for field weakening control over the DC generator in order to manipulate the generated voltage. The speed produced by the ASM emulates the wind resource. For each speed point, a voltage is generated according to the emulated production curve. Finally, the generated voltage delivered by the DC machine is regulated to a constant 48Vdc bus. This paper describes also the models of the DC generator and of the DC/DC power converters.

7 citations


Proceedings ArticleDOI
01 Oct 2017
TL;DR: In this article, the authors used variable frequency drives to perform IEEE 112B and IEC 60034-2-1 tests and demonstrated the feasibility of the proposed concept for measuring machine efficiency with a PWM power source.
Abstract: Induction motor loss segregation and efficiency measurement requires loading dynamometers and other equipment such as a variable voltage sinusoidal power supply. These are expensive and not often available even when a loading device is accessible. Variable frequency drives are now widely used for operating induction machines and are more widely available and less expensive. However, their use in place of a fixed frequency sinusoidal power supply to directly measure machine efficiency is intriguing, but inherently challenging due to the PWM output voltage. This paper presents some investigations for using variable frequency drives to perform IEEE 112B and IEC 60034-2-1 tests. The use of the drive, the measurement criteria and procedures are reported and discussed. The results presented demonstrate the feasibility of the proposed concept for measuring machine efficiency with a PWM power source.

7 citations


Proceedings ArticleDOI
01 Apr 2017
TL;DR: In this article, the authors discuss system level challenges faced in designing and commercializing a variable frequency drive (VFD) system utilizing high speed, high voltage, and high power density switching devices that incorporate Silicon Carbide (SiC) MOSFET technology.
Abstract: This paper discusses system level challenges faced in designing and commercializing a Variable Frequency Drive (VFD) system utilizing high speed, high voltage, and high power density switching devices that incorporate Silicon Carbide (SiC) MOSFET technology.

Patent
08 Sep 2017
TL;DR: In this paper, a smart power module and a variable frequency drive are presented, which includes an upper bridge arm drive circuit and a lower bridge drive circuit connected with an inverter bridge separately.
Abstract: The invention discloses a smart power module and a variable frequency drive. The smart power module includes an upper bridge arm drive circuit and a lower bridge arm drive circuit connected with an inverter bridge separately; an overcurrent protection mode selecting circuit used for receiving and outputting overcurrent protection mode signals; an overcurrent protection time delay circuit used for receiving and outputting overcurrent protection time delay signals; an overcurrent protection circuit used for outputting overcurrent detection signals after detecting that current flowing to a load connected with the smart power module is greater than a preset current value; an inverter bridge control logic circuit used for controlling the engagement and disengagement of the upper bridge arm drive circuit and/or the lower bridge arm drive circuit according to the overcurrent protection mode signals, the overcurrent protection time delay signals and the overcurrent detection signals. According to the invention, damage of the variable frequency drive caused by that current flowing through a compressor is greater than a preset value due to factors such as pressure and the like is avoided.


Proceedings ArticleDOI
01 Mar 2017
TL;DR: In this article, a novel control scheme for an open-ended winding motor dual-inverter drive, where a primary inverter is supplied from a dc power source and a secondary inverter from a floating dc capacitor with no power source, is presented.
Abstract: A novel control scheme is presented for an open-ended winding motor dual inverter drive, where a primary inverter is supplied from a dc power source and a secondary inverter is supplied from a floating dc capacitor with no power source Examination of the basic single phase equivalent circuit model of an induction machine reveals that near optimal motor efficiency is achieved at a relatively constant motor fundamental power factor over a wide range of motor loads and drive operating frequencies, eg 071 for the motor used in this work The drive control described uses the phase difference between the fundamental output voltages of the primary and secondary converters in order to control the motor's terminal voltage and to maintain a motor power factor of 071 This control is maintained over the full range of the motor's load and drive frequency settings The floating capacitor bridge voltage is regulated using PI feedback control, with the capacitor voltage error signal as the input and the amplitude modulation index of the primary inverter as the output The capacitor voltage reference signal is related to the per-unit drive frequency and measured current: as the motor's current or frequency changes, the capacitor's voltage reference is updated in a proportional manner to both parameters This control approach keeps the fundamental phase difference between the two inverters within a stable operating range, maintains the power factor of the main bridge close to unity, and improves the floating bridge's dc capacitor voltage stability during transient load changes The drive control performance is presented using detailed simulations and experimental testing; verifying the regulation of the floating capacitor's voltage as well as the predicted efficiency gains for the induction motor under constant power factor operation as compared with conventional drive control

Proceedings ArticleDOI
01 Jun 2017
TL;DR: In this paper, a variable frequency drive (VFD) is implemented to drive a three-phase (3φ) induction motor using battery bank and regenerative braking mechanism is used to make the system more efficient.
Abstract: Most recently, the major proportion of transporta-tion sector utilizes fossil fuels. Burning of fossil fuels adds massive amount of carbon in the atmosphere. Moreover, the fossil fuels reserves are depleting and their prices are also fluctuating. In addition, new environmental policies are also being made to reduce carbon emissions. So, electrification of the transportation sector is essential to reduce greenhouse gas emissions. This paper proposes an improved method of assembling an electric drive system. A variable frequency drive (VFD) is implemented to drive a three-phase (3φ) induction motor using battery bank. The sinusoidal pulse width modulation (SPWM) technique is used to implement the VFD. To make the system more efficient a regenerative braking mechanism is used. In addition, a solar panel is also used to supply the auxiliary loads.

Proceedings ArticleDOI
17 Mar 2017
TL;DR: This paper shows review on stimulation and performance analysis of induction motor with VFD and without VFD for pump and helps to reduce operating cost of the entire system with that provides operational benefits and improves the system life.
Abstract: Electrical Energy conservation in the field of Induction Motor is important as two-third of world's electricity consumption is done by using Induction Motor. It has been stated that most of the energy in industry is consumed by AC motors. A problem related with these induction motors that is, large starting inrush current due to this current power consumption increased. To reduced these current by using variable frequency drive (VFD). VFD is a techniques used to control the speed of AC induction motors by changing the supply frequency. These drives are used for smooth start of large motors and continuously adjust the speed. With using VFD, energy cost savings are especially in pump application where the load torque and power vary with respect to speed of the induction motor. In that system it helps to reduce operating cost of the entire system with that provides operational benefits and improves the system life. This paper contain the experimental study of induction motor with VFD and without VFD for pump. With that study analysis these paper shows review on stimulation and performance analysis of induction motor with VFD and without VFD.

Journal ArticleDOI
TL;DR: In this article, a variable frequency drive for an induction motor is proposed, which uses a power factor correction bridgeless single-ended primary inductor converter-controlled rectifier operating in discontinuous inductor current mode as a front-end in order to improve the input power quality and a variation of the constant volts per hertz controller, with feedback to regulate the velocity of the motor shaft.
Abstract: A variable frequency drive for an induction motor is proposed. The drive uses a power factor (PF) correction bridgeless single-ended primary inductor converter-controlled rectifier operating in discontinuous inductor current mode as a front-end in order to improve the input power quality and a variation of the constant volts per hertz controller, with feedback to regulate the velocity of the motor shaft. The frequency slip is measured and compensated, since the input stage. Experiments with and without load are carried out and presented. Input power quality measurements are also presented. The proposed system is effective to regulate the velocity and achieving a close to unity PF.

Book ChapterDOI
01 Jan 2017
TL;DR: This chapter discusses the basic design and construction of variable frequency drives (VFD), used to control the speed and/or torque of induction and synchronous motors at the power generation facility when speed control or torque control is required for the application.
Abstract: This chapter discusses the basic design and construction of variable frequency drives (VFD). VFD and variable speed drives (VSD) are used to control the speed and/or torque of induction and synchronous motors at the power generation facility when speed control or torque control is required for the application. The types of VFD technologies available are varied and each has its own unique advantages and disadvantages. While details of construction vary from manufacturer to manufacturer, the three main types of VFD are the voltage source inverter (VSI), the current source inverter (CSI) and the pulse width modulated inverter (PWM). Harmonic currents can have several adverse effects on the electrical distribution system feeding the drive. Some of the effects are the possible overheating of distribution equipment due to nonlinear current waveforms and increased copper and iron losses in motors and transformers.

Patent
15 Sep 2017
TL;DR: In this article, a power conversion control method and device for variable frequency drive technology is described, where an inductance voltage reference value is determined according to received input current, input voltage, phase current and a preset motor rotation speed reference value.
Abstract: The embodiment of the invention discloses a power conversion control method and device and relates to the field of variable frequency drive technology. According to the invention, an inductance voltage reference value is determined according to received input current, input voltage, phase current and a preset motor rotation speed reference value, and a q-axis voltage specified rate and a d-axis voltage specified rate are determined according to the phase current, the input current, the input voltage and bus voltage, and then a first pulse width modulation signal and a second pulse width modulation signal according to the inductance voltage reference value, the q-axis voltage specified rate and the d-axis voltage specified rate. Current of the front end of a DC bus capacitor is adjusted through the first pulse width modulation signal and voltage of a signal modulation motor is modulated through the second pulse width modulation signal, so that power balance is achieved between the frontend and the rear end of the DC bus capacitor and ripple current of the DC bus capacitor is reduced. At the same time, since the DC bus capacitor only needs to store comparatively small power, the DCbus capacitor can be replaced with a film capacitor having comparatively small capacity.

Journal ArticleDOI
01 Dec 2017
TL;DR: This paper analyzes and compares the advantages and disadvantages of several kinds of drive devices of belt conveyors from the angle of energy saving, and summarizes the application advantages and using problems of permanent magnet motor variable frequency drive system in belt conveyor.
Abstract: This paper analyzes and compares the advantages and disadvantages of several kinds of drive devices of belt conveyors from the angle of energy saving, and summarizes the application advantages and using problems of permanent magnet motor variable frequency drive system in belt conveyors. An example is given to demonstrate the energy saving effect of this system compared with other driving methods. This paper points out the application prospect of permanent magnet motor variable frequency drive system on belt conveyors and other large mining machines in coal mine. This paper is aimed to provide the design direction for the designer and the choice basis for the user on belt conveyor.

Proceedings ArticleDOI
01 Jan 2017
TL;DR: In this article, the advantages of the complex "controlled converter" for modern regulated electric drives with dual-power machines are discussed. But the authors focus on the effects of the electrical machine and the converter on the performance of the electric drive.
Abstract: The article reviews with electrical machines in modern regulated electric drives. The advantages of the complex “controlled converter — motor” for example, variable frequency synchronous drive. Specified effects on more efficient use of the active materials in the electrical machine and reduce electrical losses by varying the air gap between the rotor and the stator and rotor grooving. Two variants of the power circuits in the variable frequency synchronous electric drive with dual-power machines review. The article also indicates additional opportunities induction electric drive with modern frequency converters on the example of the electric drive of the transport roller conveyors of the electric-weld pipe workshop. Non-traditional design of the electrical machine and the converter, providing high specific indicators of the electric drive as an example of the electric drive with field regulated reluctance machine (FRRM).

Patent
01 Mar 2017
TL;DR: In this paper, the authors present systems, devices, and methods for a hybrid power delivery system with improved energy storage system power control, which includes a generator coupled to a variable frequency drive, in which a first power converter converts a first AC power from the generator to a DC power at the DC bus coupled to the second power converter.
Abstract: Disclosed herein are systems, devices, and methods for a hybrid power delivery system with improved energy storage system power control. The hybrid power delivery system may comprise a generator coupled to a variable frequency drive, in which a first power converter converts a first AC power from the generator to a DC power at the DC bus coupled to the first power converter. The DC bus is coupled to a second power converter, which converts the DC power to a second AC power. Also coupled to the DC bus is a power controller, which is also coupled to an energy storage system. The power controller is configured to regulate power flow between the energy storage system and the DC bus. The power controller may comprise at least one of a switch, a chopper circuit, a contactor, a silicon controlled rectifier, and/or a DC-to-DC converter.

Proceedings ArticleDOI
01 May 2017
TL;DR: In this paper, a single marine power system and circuit solutions for reducing the ratio of harmonics in ship networks were analyzed, and a variety of methods including application of filter-compensating devices, three-winding transformers, and electromachine converters.
Abstract: In recent years, semiconductor converters are widely applied in marine electric power systems. Semiconductor converters are used in ship electric propulsion systems consisting of shaft generator units, a variable frequency drive, and alternators. The use of semiconductor converters results in decrease of power quality in ship networks, in particular, in an increased ratio of non-sinusoidal voltage waveforms (harmonic distortion). Rules of the Russian Maritime Register govern the maximum allowable distortion in the power network for a correct functioning of ship equipment. Improvement of power quality is achieved with a variety of methods including application of filter-compensating devices, three-winding transformers, and electromachine converters. The paper analyzes a single marine power system and circuit solutions for reducing the ratio of harmonics in ship networks.

Patent
Cheng Xiaomeng1, Li Huaqiang1, Zhu Peijun1, Wu Dongxiao1, Wang Kayle1, Zhang Qian1 
05 Oct 2017
TL;DR: In this article, a system and method for speed regulation of a VFD circuit via an anti-windup control scheme that provides consistent speed response with no overshoot is disclosed.
Abstract: A system and method for speed regulation of a VFD circuit via an anti-windup control scheme that provides consistent speed response with no overshoot is disclosed. A control system for operating the VFD circuit includes a feedback controller programmed to receive a speed of a motor operating responsive to an initial torque command and process the speed of the motor to generate a feedback controller output. A feedforward controller of the control system is programmed to process a speed reference to generate a feedforward controller output. A command module of the control system is programmed to determine a torque command based on the processed outputs of the feedback and feedforward controllers and operate the VFD circuit to control the motor according to the torque command.

Journal Article
TL;DR: In this paper, the performance characteristics of a multistage electric submersible pump with its power supply through a variable frequency drive (VFD) were evaluated at various frequency settings.
Abstract: Electric submersible pumps (ESPs) are widely used in agricultural, petroleum and various other industries. These pumps are mostly driven at a constant speed since an ac motor is normally used as the drive. However, ESPs can also be operated at various speeds by the use of a variable frequency drive (VFD). The scope of this study is to experimentally investigate the performance characteristics of a multistage electric submersible pump with its power supply through a VFD. First a load test was conducted on the motor alone as per relevant Indian Standard at various supply frequencies. the data of load test on motor was used to evolve a novel method to calculate slip of the motor from the input power. This was applied to the test results of pump obtained at various frequency settings to determine its performance at different speeds.

Journal ArticleDOI
01 Oct 2017
TL;DR: In this article, the authors consider the calculation of modulation power losses in a system "induction motor-inverter" for various pulse width modulation (PWM) methods of the supply voltage.
Abstract: We consider the calculation of modulation power losses in a system "induction motor–inverter" for various pulse width modulation (PWM) methods of the supply voltage. Presented values of modulation power losses are the result of modeling a system "DC link - two-level three-phase voltage inverter - induction motor - load". In this study the power losses in a system "induction motor - inverter" are computed, as well as losses caused by higher harmonics of PWM supply voltage, followed by definition of active power consumed by the DC link for a specified value mechanical power on the induction motor shaft. Mechanical power was determined by the rotation speed and the torque on the motor shaft in various quasi-sinusoidal supply voltage PWM modes. These calculations reveal the best coefficient of performance (COP) in a system of a variable frequency drive (VFD) with independent voltage inverter controlled by induction motor PWM.

Patent
Richard H. Osman1
13 Jan 2017
TL;DR: In this article, a phase-locked-loop (PLL) circuit with a proportional integral (PI) regulator and a variable frequency drive (VFD) was proposed for controlling an alternating current (AC) electrodynamic machine (390) with a VFD.
Abstract: Systems and method for controlling an alternating current (AC) electrodynamic machine (390) with a variable frequency drive (VFD) (380) include a control system (300) with a phase-locked-loop (PLL) circuit (382) for providing a stator flux angle signal (338) to the VFD (380), the PLL circuit (382) comprising a proportional integral (PI) regulator (332) providing an output signal (334); and a feedforward generator (350) in communication with the PLL circuit (382), wherein the feedforward generator (350) tracks a stator flux position of the AC electrodynamic machine (390) such that the feedforward generator (350) determines a stator frequency signal (352) based on stator flux signals (308, 310, 312) and supplies the stator frequency signal (352) downstream of the PI regulator (332), and wherein the stator frequency signal (352) is summed with the output signal (334) of the PI regulator (332) to provide a dynamically adapted output signal (335) of the PI regulator (332), and wherein the adapted output signal (335) is used to determine the stator flux angle signal (338).

Journal ArticleDOI
TL;DR: In this paper, a hybrid-electric turbocharger, variable-frequency drive (VFD), and novel sensorless control algorithm were developed, which can lead to better overall vehicle performance, emissions, and efficiency while allowing for further engine downsizing and increased power density.
Abstract: Electrically assisted engine boosting systems lend themselves to better throttle response, wider effective operating ranges, and can provide the ability to extract excess energy during deceleration and high-load events (and store it in a vehicle's onboard batteries). This can lead to better overall vehicle performance, emissions, and efficiency while allowing for further engine downsizing and increased power density. In this research effort, a hybrid-electric turbocharger, variable-frequency drive (VFD), and novel sensorless control algorithm were developed. An 11 kW permanent-magnet (PM) machine was coupled to a commercial turbocharger via an in-line, bolt-on housing attached to the compressor inlet. A high-efficiency, high-temperature VFD, consisting of custom control and power electronics, was also developed. The VFD uses SiC MOSFETS to achieve high-switching frequency and can be cooled using an existing engine coolant loop operating at up to 105 °C at an efficiency greater than 98%. A digital sliding mode-observer sensorless speed control algorithm was created to command and regulate speed and achieved ramp rates of over 68,000 rpm/s. A two-machine benchtop motor/generator test stand was constructed for initial testing and tuning of the VFD and sensorless control algorithm. A gas blow-down test stand was constructed to test the mechanical operation of the hybrid-electric turbocharger and speed control using the VFD. In addition, a liquid-pump cart was assembled for high-temperature testing of the VFD. Initial on-engine testing is planned for later this year. This paper intends to present a design overview of the in-line, hybrid-electric device, VFD, and performance characterization of the electronics and sensorless control algorithm.

Journal ArticleDOI
E. S. Trunin, V. M. Tarakanov, S. P. Boikin, S. I. Smirnov, D. S. Genvarev1 
TL;DR: In this article, the authors examined the features of oscillations in the reducing gear when resonant torsional oscillations are present in the drive sleeve and proposed that gas turbine units without, rather than with, gearing be used in isolated power systems for operation with a variable frequency drive and for maintaining the balance between the nonlinear and linear components of the load.
Abstract: Low-frequency (sub-synchronous) oscillation effects in geared gas turbine units that lead to the shutdown of the units and to breakdown of the power system are examined. The reasons are complicated and depend on the operation of variable frequency drives and the design features of the gas turbine unit. Data from tests by the firm JSC “Diamekh 2000” are presented. This paper examines the features of oscillations in the reducing gear when resonant torsional oscillations are present in the drive sleeve. It is proposed that gas turbine units without, rather than with, gearing be used in isolated power systems for operation with a variable frequency drive and for maintaining the balance between the nonlinear and linear components of the load.

Patent
04 May 2017
TL;DR: In this paper, a dynamic linear motor is controlled by determining a relative proximity of a moving rotor of the linear motor to a fixed stator segment of a linear motor using a current location of the moving rotor.
Abstract: A dynamic linear motor is controlled by determining a relative proximity of a moving rotor of the linear motor to a fixed stator segment of the linear motor using a current location of the moving rotor. A current driving characteristic of the linear motor at the current location of the moving rotor is determined. Settings for the fixed stator segment when the moving rotor reaches the fixed stator segment are identified based on the current driving characteristic. The fixed stator segment is driven based on the settings when the moving rotor reaches the fixed stator segment.