# You asked: When the field of a DC motor is weakened the speed of the motor is?

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## What is field weakening in DC motor?

Field weakening is a method of raising the speed in DC motors. If the field (magnetic field) is weakened by reducing field current, back emf is reduced and thereby more armature current is drawn. Now torque is produced due to interaction of armature current and field flux.

## What is field weakening in motor?

Field-weakening or flux-weakening is a technique for increasing the speed of an electric motor above its rating at the expense of reduced torque. … The torque speed characteristic curve in Figure 2 shows that the motor’s back EMF (stator voltage) rises in proportion to the motor speed.

## Why does the speed of a shunt motor increase when the field is weakened?

Speed of the shunt motor varies directly with the CEMF and inversely with the magnetic strength of the field windings. The larger the CEMF, the faster the motor will run. … Because the series field has only a few turns and is weak, this motor is still basically a shunt type and no name change is necessary.

## What affects the speed of a DC motor?

DC Motor Speeds

The number of wire turns in an armature, the operating voltage of the motor, and the strength of the magnets all affect motor speed. If a DC motor is running on a 12 V battery, that is the maximum voltage available to the unit and the motor will only be able to perform at a speed rated for 12 V.

## What is field weakening range?

The frequency range below the nominal frequency is called a constant flux range. Above the nominal frequency/speed the motor operates in the field weakening range. … This means that the maximum torque is approximately a constant at the constant flux range.

## What is field weakening in Pmsm?

Description. The PMSM Field-Weakening Controller block implements a field-weakening controller for a permanent magnet synchronous machine (PMSM). … The block decreases the PMSM phase voltage by adjusting the angle of the reference current vector when the voltage vector magnitude exceeds its limit.

## What are the methods of speed control of DC motors?

Thus, the speed of a DC motor can control in three ways:

• By varying the flux, and by varying the current through field winding.
• By varying the armature voltage, and the armature resistance.
• Through the supply voltage.

## 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.

## What is flux weakening in induction motor?

Abstract: Flux-weakening control for induction motor (IM) in voltage extension region (outside the inscribed circle but in the hexagon) is meaningful to yield a further maximum torque. However, as the voltage-limit trajectory migrates out of the inscribed circle, torque ripple becomes more severe.

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## How speed of the DC shunt motor can be increased?

How speed of the DC shunt motor can be increased? … Decreasing armature current will help in increasing speed for DC shunt motor. Since load current is addition of armature current and field current we’ll get less armature current for more field current.

## When the speed of DC motor is increased?

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. So, the correct answer is “Option B”.

## What is the effect on motor speed if the field current is increased?

Therefore, the motor speeds up. When the field current is increased, the field flux is increased. More counter EMF is developed, which opposes the armature current. The armature current then decreases, and the motor slows down.

## What affects the speed of a motor?

The rotating speed of an electric motor depends on two factors: its physical construction, and the frequency (Hz) of the voltage supply. Electrical engineers select the speed of a motor based on the needs of each application, similar to how the mechanical load determines the horsepower required.

## What is motor speed?

Speed: The speed of a motor is defined as the rate at which the motor rotates. The speed of an electric motor is measured in revolutions per minute, or RPM. Torque: The torque output of a motor is the amount of rotational force that the motor develops.