What is field weakening in AC motors?

What is field weakening range?

Above the nominal frequency/speed the motor operates in the field weakening range. In the field weakening range the motor can operate on constant power which is why the field weakening range is sometimes also called the constant power range.

What is a field weakening mode of induction motor?

The field weakening can be obtained easily for an induction motor when its supply frequency is increased without proportionally increasing the motor terminal voltage. On the contrary, from the word “permanent,” the motor terminal voltage may not easily be reduced when the supply frequency goes up.

What is FOC algorithm?

Field-oriented control (FOC), or vector control, is a technique for variable frequency control of the stator in a three phase AC induction motor… Block Diagram.

What is flux weakening in motor?

Flux weakening uses stator current components to counter the fixed-amplitude magnetic airgap flux generated by the rotor magnets, performing a role similar to field weakening in a separately excited dc motor.

Which motor Cannot be started on no load?

A series motor should never be started at no load. With no mechanical load on the series motor, the current is low, the counter-EMF produced by the field winding is weak, and so the armature must turn faster to produce sufficient counter-EMF to balance the supply voltage. The motor can be damaged by overspeed.

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What is flux weakening in induction motor?

Abstract. The high-speed operation of the field oriented induction motor control requires a flux decreasing to counteract the back electromotor force (EMF) increasing that will approach the available inverter voltage. Decreasing the flux causes the available torque is reduced.

What is EMF and back EMF?

Counter-electromotive force (counter EMF, CEMF), also known as back electromotive force (back EMF), is the electromotive force (voltage) that opposes the change in current which induced it. CEMF is the EMF caused by magnetic induction (see Faraday’s law of induction, electromagnetic induction, Lenz’s law).

How does field weakening work?

Field weakening

When the field is weakened, the back-emf reduces, so a larger current flows through the armature winding and this increases the speed. Field weakening is not used on its own but in combination with other methods, such as series-parallel control.

What is mtpa control?

The MTPA Control Reference block computes the d-axis and q-axis reference current values for maximum torque per ampere (MTPA) and field-weakening operations. … The block computes the reference current values by solving mathematical relationships. The calculations use SI unit system.

What is flux weakening for high speed operation?

The high speed implies a big electromotive force and requires flux-weakening. Usual control algorithms do flux-weakening by adding negative I d current when the required voltage by the current regulation exceeds the maximum voltage depending on the battery.

When the speed of DC motor is increased?

Complete answer:

From the equation. (3) we can say, speed is inversely proportional to armature current. Thus, when the speed of the dc motor is increased, the armature current will decrease.

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