# What is field weakening in DC motor

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The speed of a DC motor can be increased by 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 field weakening mode control?

The project, with the title Torque Control in Field Weakening Mode, is a proposal from Danfoss. The main idea of the project is to control the speed and torque of an Interior Permanent Magnet Synchronous Machine(IPMSM) in the flux weakening regime, considering the voltage and current limits of the inverter .

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

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.

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## 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 is Field in DC motor?

A field coil is an electromagnet used to generate a magnetic field in an electro-magnetic machine, typically a rotating electrical machine such as a motor or generator. It consists of a coil of wire through which a current flows.

## Why starters are required in a DC motor?

Starters are used to protect DC motors from damage that can be caused by very high current and torque during startup. They do this by providing external resistance to the motor, which is connected in series to the motor’s armature winding and restricts the current to an acceptable level.

## What is flux weakening for high speed operation?

Flux weakening allows a machine to operate above base speed in constant-power, high speed region when there is a fixed inverter voltage and current [7] . Below rated speed, all of the stator current can be used to produce torque. …

## How long can a DC motor run continuously?

You should anticipate, given proper attendance, that the motor can run continuously for the life of its brushes, which should be in the range of six months to a year. Presuming that the motor is too small to have its brushes changed by a trained electrician while running.

## What are the disadvantages of DC motor?

• High initial cost.
• Increased operation and maintenance cost due to the presence of commutator and brush gear.
• Cannot operate in explosive and hazard conditions due to sparking occur at brush (risk in commutation failure)

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## What are the advantages of DC motor?

DC motors have the advantage of: higher starting torque, quick starting and stopping, reversing, variable speeds with voltage input and they are easier and cheaper to control than AC. AC motor advantages include: lower power demand on start and minimal maintenance.

## What are the 3 types of DC motors?

Types of DC Motors. There are 3 main types of DC motor that are available:- Series, Shunt and Compound. These terms relate to the type of connection of the field windings with respect to the armature circuit.

## What is back emf in dc motor?

A motor has coils turning inside magnetic fields, and a coil turning inside a magnetic field induces an emf. This emf, known as the back emf, acts against the applied voltage that’s causing the motor to spin in the first place, and reduces the current flowing through the coils of the motor.

## How does a DC commutator work?

Commutators are used in direct current (DC) machines: dynamos (DC generators) and many DC motors as well as universal motors. In a motor the commutator applies electric current to the windings. By reversing the current direction in the rotating windings each half turn, a steady rotating force (torque) is produced.