What Is Vector Control Vfd?


Author: Roslyn
Published: 6 Dec 2021

The Park Transformation

The Park transformation is used in the analysis and study of machines. The transformation is the most important concept for understanding how FOC works, it was first proposed in a 1929 paper by Robert H. Park. Park's paper was ranked second most important in terms of impact from all power engineering papers ever published.

Park's work involves his ability to transform any machine's linear differential equation set from one with time coefficients varying to another with time invariant coefficients, resulting in a linear time-invariant system. The park transform can be used to convert the system of three phase currents and voltages into a two coordinate linear time-invariant system. The system is made to make it easy to implement PI controllers and also to simplify the control of flux and Torque.

Universal variable Frequency AC-DCAC motor

The three-phase 380V alternating current has a theoretical direct current of 537V after rectification, and the lytic Capacitors have a 400V withstand voltage. Only two-stage electrolytic capacitors in series can be used to make the filterCapacitor The two electrolytic capacitors have different service lives because the capacity of the electrolytic capacitors cannot be identical.

The two electrolytic capacitors must be connected in parallel with the same voltage-balancing resistors. The output voltage of the universal variable Frequency output is 380650V, with an output power of 0.75400kW, a working Frequency of 0400Hz, and an AC-DC-AC main circuit. The control system has been passed down for four generations.

The goal is to approximat the ideal circular rotating magnetic field trajectory of the motor air gap, generating three-phase modulations all at once, and controlling in the manner of inscribed polygons approaching them. It has been improved after practical use, in that the addition of Frequency Compensation can eliminate speed control error, and the amplitude of the flux linkage is estimated through feedback to eliminate the influence of stator resistance at low speeds. The output voltage and current are closed-loop to improve accuracy and stability.

The system performance has not improved because the control circuit has many links. AC-DC-AC frequencies include VVVF, vector control, and direct Torque control frequencies. The input power factor is low, the DC circuit requires a large energy storage Capacitor, and the regenerative energy cannot be transmitted back to the grid.

The matrix AC-AC frequency conversion was invented. The matrix AC-AC frequency conversion eliminates the DC link, which means the huge and expensive electrolyticCapacitor is eliminated. Start the motor with city power, which will start the motor at a higher current than the rated current.

The three-phase system and the plane

The three-phase system is changed to a two co-ordinate system. The Ia and Ib are components of the plane, but the Io is not important.

VFD-Controlled Motors

Electric motor can be used to run a wide array of applications to achieve control that is not possible with mechanical means. Users can match motor speed to maintain system demand with the help of VFD-controlled motors. Most VFD applications improve system efficiency and provide a return on the investment in energy savings in less than a year.

The most advanced motor control method is closed-loop. Closed-loop vector control uses a motor encoder to provide precise speed feedback and eliminate any error in the control of the motor. The motor is responding to the load if the encoder is added.

Many extruders use feedback from an electronic device to maintain their speed. The VFD can react to high Torque conditions that may cause damage to the machine by using Encoder feedback. The same tuning requirements are required in closed-loop vector control to maximize motor control and reduce compensation.

Although the motor is a natural soft starter, it can exceed its rated currents for brief periods of time. High currents can lead to excessive heat in the motor, which can lead to reduced lifetime and premature failure. There are also locked rotor conditions that can be caused by mechanical damage.

Increased current draws can be caused by load wear and can be in excess of motor FLA. A run command speed reference are required at every moment of the operation of a VFD. The run command tells the drive to operate the motor, while speed reference tells the VFD what frequencies to run.

Variable Frequencies Ionized Motors

The simple, reliable solution for power industry has been the ionized motor. New technologies and the need for ever increased efficiency have encouraged the development of different types of motors that can be driven by variable frequencies.

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