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.

Harmonic Mitigation in VFD Controlled Chiller Compressor Using AC Line Reactor and DC Link Choke Combination

Abstract: With the goals of a better power factor and reduction in energy use, variable frequency drives (VFDs) have been standardized in various industrial applications including Heating, Ventilation, and Air-conditioning (HVAC) systems. However, key issues related to the deterioration in the power quality associated parameters (voltage harmonic distortion and current harmonic distortion) due to the growing number of VFDs demand a wholesome analysis of the problems faced by the users. In this present work, an analysis has been performed to investigate the potential impact of using alternating current (AC) line reactor and direct current (DC) link choke combination on harmonic mitigation in a VFD driven water-cooled centrifugal chiller compressor. Using a combination of AC line reactor and DC link choke as one of the low cost solutions in harmonic mitigation of a VFD driven load in HVAC systems can be decided based on the investigation done in this research work.

Air conditioner variable frequency drive plate refrigerant cooling anti-condensation control method

Abstract: The invention relates to a variable frequency air conditioner technology, discloses an air conditioner variable frequency drive plate refrigerant cooling anti-condensation control method, solves the problem of condensation generated by variable frequency drive plate refrigerant cooling, and improves the electric control reliability. According to the method, whether an electronic expansion valve iscontrolled according to condensation prevention or not is determined according to the difference value between the temperature of a refrigerant pipe heat dissipation pipe and the temperature in a variable-frequency drive plate, the temperature of the refrigerant pipe heat dissipation pipe is higher than the dew point temperature of the variable-frequency drive plate, condensation water is prevented, and product reliability is guaranteed. The scheme is suitable for anti-condensation control of a variable frequency air conditioner.

Voltage following device and method and variable frequency drive control loop

Abstract: The invention provides a voltage following device and method, and a variable frequency drive control loop. The voltage following device comprises a rectification module, an inversion driving module, avoltage reduction module, a voltage sampling module, a current sampling module and a voltage following control module, wherein the output end of the inversion driving module is connected with the current sampling module, the current sampling module is used for collecting present current, the voltage sampling module is used for collecting a current bus voltage, and the voltage following control module is used for calculating the current running rotating speed of a load according to the present current and executing voltage boosting operation or voltage reducing operation according to the current running rotating speed and the current bus voltage. According to the invention, the reference bus voltage for controlling the rectification module to execute voltage boosting and the voltage reduction module to execute voltage reducing is determined by judging different rotating speeds of a load, so that the bus voltage is adjusted in real time, and the bus voltage of the variable frequency driving control loop is ensured to be in an optimal state in real time so as to improve the driving efficiency and reliability.

Electronically controlled high efficiency induction motor

Abstract: The present invention provides electronically controlled high efficiency induction motor having low power consumption due to additional winding provided over the normal winding in the stator (1) that develops back emf, by which part of the power requirement is met and an electronic module through which electric power is supplied to the motor. The electronic module is having a micro controller (6) that controls the voltage frequency and the capacitance of the motor from lower to higher limit; a variable frequency drive (7) that stabilize the frequency at a constant limit; relay switch(8) that helps for switching (on/off) the motor and selects the capacitor, from the capacitor bank (13) based on the load of the motor, measured by the Current Transformer coils (10) that transmit to the microcontroller; step down transformer (11) that provides low voltage for the working of the electronic module and integrated Circuit (12).

Clean power powerbus variable frequency drive system

Abstract: A N pulse variable frequency drive for driving two or more motors that is the combination of two or more variable frequency drives with each drive driving an associated one of the two motors One application is a decanter centrifuge which has a main motor to drive the bowl and a back motor to drive the conveyor One of the two variable frequency drives drives the main motor and the other drive drives the back motor The variable frequency drives are connected to a common buss and to a N pulse phase shifting transformer