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.

Air cooled variable-frequency drive

Abstract: Methods and apparatus for simultaneous operation of a variable-frequency drive (VFD) and a controller. The VFD drives an electric motor of a drilling rig machine. The controller controls temperature of an insulated-gate bipolar transistor device (IGBT) of the VFD by controlling an air mover in response to real-time temperature data. The air mover generates airflow into a passage, the airflow thereby interacting with radiating members extending into the passage from a heat sink thermally coupled with the IGBT in the inner housing outside the passage.

Influence of defects in windings insulation on its operation reliability

Abstract: Low-voltage induction motor is one of the most widely used types of electrical machines. Today more and more end users demand reliable and energy efficient electrical machines as an extra feature. Design and applying of control systems for improving energy efficiency must be in correlation with reliability requirements; it is necessary to fetch out the changing operation conditions that can lead to unexpected failures, and to prevent them. This paper describes the influence of insulation defectiveness on winding insulation system reliability in PWM based regulation applications. Currently, the influence of technological defects in the winding insulation on its reliable operation in motor being part of the variable frequency drive has not been thoroughly studied. The relevance of this research is determined by the need to study the “healing” of winding insulation through defects by the impregnation, and its influence on the mean time to failure. The study results will permit to give recommendations for improving the reliability of low voltage windings and subsequently the reliability of induction motors fed by PWM invertors. The study was carried out using a test technique adapted to variable frequency drives and applied to insulation system “varnish — enamelled winding wire”. The experimental results are presented and the main findings are discussed.

Cyclonic dust collector with variable speed drive and constant load current

Abstract: A dust collection arrangement employs a variable frequency drive to supply AC to its fan motor. A current sensor measures the current drawn by the motor, and this is compared with a preset value. The variable frequency drive adjusts the frequency of the AC applied to the motor to maintain the motor current at the preset level. This keeps the flow of air in the system optimal as dust producing tools are added or taken off.

Refrigerant compressor drives offering enhanced robustness, efficiency and rated voltage operability

Abstract: Apparatuses, methods, and systems offering enhanced robustness, efficiency and rated voltage operability for refrigerant compressor drives are disclosed. An exemplary embodiment is a method of operating a variable frequency drive. The method includes operating the drive over a first operating range to provide at least a desired operating speed and minimize d-axis current, operating the drive over a second operating range including injecting d-axis current to provide at least the desired operating speed, operating the drive over a third operating range at a de-rated speed less than the desired operating speed. In the first operating range the drive input voltage is greater than a first value. In the second operating range the drive input voltage is lower than the first value and greater than a second value. In the third operating range the drive input voltage is lower than the second value.