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.

Novel electric drive with power-regenerating capability: modeling and simulation

Abstract: This paper provides a detailed modeling of the variable voltage variable frequency drive system (VVVF) proposed by previous research. The AC/DC converter performance at low speed is tested and propulsion drive startup has been evaluated. The ability of the drive to provide power regeneration has been investigated, and the simulations suggest that the VVVF drive would have the ability to support substantial levels of pulse loads.

Operational Parameters Affecting Harmonic Resonance in Electrical Submersible Pump Systems

Abstract: Electrical submersible pump (ESP) systems in the oil field have unique features due to the long cabling effect. The electrical system for a typical ESP installation consists of a variable frequency drive (VFD), a multi-tap step-up transformer, a surface cable, a downhole main cable, a motor lead extension (MLE) cable, and an electrical submersible motor. A load filter is usually required in a VFD-ESP system. In this paper, several operational parameters that can significantly affect operating conditions of an ESP system are demonstrated through field measurements and simulation of a practical ESP system currently in operation in Alberta, Canada. The simulation model is also validated by comparing with field measurement data. This analysis is beneficial to field engineers and ESP system operators to understand better the impacts of equipment parameter settings.

Generators operating with variable frequency drives in an offshore facility

Abstract: Due to wide application of Variable Frequency Drives (VFDs), it becomes common that a dedicated generator supplies power to a VFD in the offshore oil field. In this paper, a case study was conducted and analyzed for a generator instability issue when operating with a VFD. Serious current oscillation happens between the generator output and the drive input at two electrical submersible pump (ESP) systems consisting of a dedicated generator and a VFD in each well. Minor changes of certain parameters and settings of the two ESP systems could trigger current oscillation at the input of the drives, also a current fluctuation at the ESP motors connected to the output of the drive and thus serious vibration of the ESP pumps. The analysis indicates that the low DC link voltage at the drives and the low displacement power factor at the drive input are the root causes of the problem. Effective solutions for this type of instability problem are proposed in this paper.

Speed computation function for induction motor/blower systems control algorithm

Abstract: An apparatus and method for controlling an induction motor having a variable frequency drive in a blower system so that the blower system provides a specific fluid flow. A start-up program causes the motor to ramp up to approximately a predetermined steady state speed. A required blower torque is calculated by operating on a table of blower constants, a selected flow rate and a motor speed. The motor speed is calculated by operating on a table of motor specific constants, a voltage-frequency index and a measured direct current bus current. A developed motor torque is calculated by operating on a table of motor specific constants, a voltage-frequency index and the calculated motor speed. The calculated required blower torque is repeatedly compared with the calculated developed motor torque. The voltage-frequency index to the variable frequency drive is modified to force the developed motor torque to converge with the required blower torque in a steady state.

Networked control of single-phase induction motor air conditioners for constrained power systems

Abstract: Split-Type Air Conditioners (ACs) are extensively used in households, commercial organizations and industrial setups. The duty-cycle based hysteretic control is inefficient and requires high power provisioning of full startup current for the compressor at each turn-on. This is especially demanding in constrained power systems with weak grids where people are dependent on backup generators and UPS for power needs during load-shedding. Some work has been done on optimizing energy consumption of Split-type ACs based on DC Compressors e.g. permanent magnet brushless DC motors (PMBLDCM) and three-phase induction machines but limited work has been done on operational optimization and energy efficiency of Split-type ACs based on single phase permanent split capacitor induction motors (SPPSCIM). This paper presents a networked Variable Frequency Drive (VFD) for these ACs to optimize operation, enhance energy efficiency and increase load drive capability of constrained energy systems. The network mode of operation allows existing installed base of standalone units to be integrated with central control infrastructure in an organization through Building Management Systems (BMS). The drive is designed, and tested on a 2.3kW Mitsubishi Electric Split-type air conditioner with SPPSCIM. The results of implemented VFD with networked control over Wi-Fi are presented to validate the effectiveness of the speed drive and the enhanced capability enabled by networked operation.