Question

Prelab . Describe what the magnetizing curve of a DC motor that uses windings on the stator to generate magnetic field in the motor is. What is the equivalent circuit of a DC motor that uses windings on the stator to generate magnetic field in the motor? Show the equivalent circuits of both stator and rotor. What are the formulas for the torque and the induced voltage? If the voltage of the external supplies for the stator winding and the rotor winding, the resistance of the stator winding and resistance of the rotor windings, and the torque loss in the motor are considered constant, how the rotor speed changes as the torque of the external mechanical load increases?

Answer 1

magnetic field magnetic field angle between when , an nothing but opposition to mainmme As per the principle of the notor when a wire carrying current inside it experiences ce force que force is known as Lorentz force (F) f Bil sind where, B = flux a density of Current theat flows through conductor e = length of the conductor conductor & freux. flur & current are perpendiculas to each other f = Bil For DC notoy case: rotor & rotor is * The conductor related to armature in DC motor. an fielel The magnetic field is produced by coil C could be shunt or series connected) the fieles Coil is nothing but thertutor in Ce DC motor. MMF = If Nf mmf Arrature org Fisi Genereld may netization Corove] Rotor where, N= No. of turns of field winding main field flux If fired current Ra Armature resistance of Crotor) 1) motor Ea - Baek emf that was developed the motor ohren opposes by the supply Voltage eft filds resistance Note The is armature reaction nom for which arma could develop j.P. FATA But let's neglect armature reaction for our case. IF la V Ra TE a sh om fieles con Stator arm uf If Ea= koo [ ka motor constant] Ta kola ; la Armature corrent. (Torque wa Angular rotation revolution (seea. Tested by neutre factors to Hence, Test = ko wgeer. E How the magnetization curre is as following: Ear [fis: Magnetization Curre] Is Hote: Instead of the Ea developing at origin it is generated a some value not cet origin due to residuas magnetizm. But for no notor developed power Pdev. Ea la 27N in dop.m. ce here, Negetation rotation per minute) Ece la Ea la 2 TN unit. Nom T 9.55 Eala (menit: nom when 2 mechanical loaes charges the speed also changes hence the torque is also affecteel.