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.

System and method for consistent speed regulation in a variable frequency drive

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.

The Influence of Main Pump with High-Voltage Variable Frequency Drives on Electric Motors Periodic Repair

Abstract: The main objective of the work - to investigate the effect on the wear of high voltage electric motors of main pump units periodic switching on and off in cyclical pumping. Frequent starts motors in a cyclic pumping lead to accelerated wear of the mechanical parts of the motor due to the impact of dynamic loads at start-up, as well as winding insulation due to high inrush currents flow. As a result of accelerated depreciation may decrease residual life, overhaul period and service life of electric motors. The main factor affecting the service life of insulation motors are winding temperature, and as a consequence, the thermal aging of the insulation. The use of variable frequency drive can significantly reduce the cyclic transfer modes, or even eliminate them. The authors obtained analytical expressions for the evaluation of insulation deterioration at the start of the motor, which allow us to study the impact of the following factors: insulation class, the start time, break time at work, initial and nominal temperature, the temperature rise of the windings over the ambient temperature. The effect on the deterioration of the insulation cold start and hot conditions, as well as the percentage of the hottest start-ups in the total number of starts. Obtained expressions for the depreciation of isolation to determine the change timing of overhauls of high voltage electric main pump units. The developed method was approved by the example of the use of a variable frequency drive on the oil pumping stations construction section Leninsk-Nurlino trunk pipeline Nizhnevartovsk - Kurgan - Kuibyshev. The analysis showed that the installation of a variable frequency drive motors on three main pump units technological area of the number of starts to decline by 14%. The results can be used for pipeline transport of oil companies when planning the timing and costs of the current and capital repairs of high voltage electric motors main pump units.

Diagnostics for systems including variable frequency motor drives

Abstract: One embodiment is a diagnostic method for a system including setting a first diagnostic code based upon a condition of a DC bus of a variable frequency drive during a first drive state, setting at least one additional diagnostic code based upon a condition of at least one motor phase current during a second drive state, outputting first diagnostic information indicating a malfunction of the variable frequency drive if the first diagnostic code indicates a first error, and outputting second diagnostic information indicating a malfunction of a motor or a connector coupling the motor and the drive if the at least one additional diagnostic code indicates a second error.

Evaluating the Performance of Electric Submersible Pump under Various Speeds of Operation

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.