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.

Submersible pump system

Abstract: A submersible pump system includes a submersible pump assembly having one or more stages of impellers and a submersible motor assembly that drives the pump assembly. The submersible pump assembly includes a motor housing, a motor within the motor housing for driving the pump assembly and a control module mounted to the motor housing for operating the motor. The control module is electrically connected to a power line and comprises a controller and a variable frequency drive driven by the controller. The controller operates the variable frequency drive to drive the motor to maintain a constant pressure output condition from the pump assembly.

System and method for using a photovoltaic power source with a secondary coolant refrigeration system

Abstract: A secondary coolant refrigeration system powered primarily by a photovoltaic source and by an alternating current (AC) source as a backup is disclosed. The secondary coolant refrigeration system has a pump for pumping secondary coolant fluid through a secondary coolant fluid loop. The system includes a variable frequency drive for controlling the speed of the pump. The variable frequency drive includes drive circuitry configured to provide variable frequency power to the pump via an output interface. The variable frequency drive also includes a first interface configured to receive power from the photovoltaic source and a second interface configured to receive power from the AC source. The circuit is further configured to cause the variable speed drive to be powered by the photovoltaic source when the power received from the first interface is adequate and by the AC source when the power received from the first interface is not adequate.

Variable frequency drive self-check

Abstract: Diagnostic and/or control methods, systems and apparatuses for variable frequency drives are disclosed. The variable frequency drive may be controlled by a controller that may conduct one or more tests or evaluations. The tests or evaluations may include determining whether a switching device in the variable frequency drive is open-circuited, short-circuited, or operating normally. The tests may include determining whether current provided at an inverter output of the variable frequency drive is within a predetermined range. An exemplary embodiment evaluates the drive for a short circuit condition, an open circuit condition, and a sensor error or failure condition, controls operation of the drive based upon these one or more evaluations, may abort operation of the drive based upon one or more evaluations, and may set a fault code indicative of the type of error encountered.

Control algorithm for brushless DC motor/blower system

Abstract: An apparatus and method for controlling a brushless direct current motor having a pulse width modulated 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 which is read from a commutation Hall sensor in the motor. A developed motor torque is calculated by operating on a table of motor specific constants, a modulation index and the motor speed taken from the commutation Hall sensor. The calculated required blower torque is repeatedly compared with the calculated developed motor torque. The modulation index to the pulse width modulated variable frequency drive is modified to force the developed motor torque to converge with the required blower torque in a steady state.

Starting large synchronous motors in weak power systems

Abstract: Utility company standards for power quality are making it difficult for industrial users to start large induction and synchronous motors due to high inrush current. This paper will present a large oil company's challenges starting large motors driven by the utility company in a relatively weak power system in East Texas while not violating the Utility company's standards. A workable solution is an air cooled pulse width modulated (PWM) voltage source variable frequency drive (VFD) system designed to start multiple large horsepower, medium voltage synchronous motors without any measurable voltage flicker. Various combinations of motor design (induction vs. synchronous) & starting methods are reviewed and final design schematic diagrams are documented. Challenges encountered during the design & start-up are described and solutions with final performance details are provided.