Dc Machine :: essays research papers

2a.i) Startup of a linear DC machineStartup of a linear DC machine (See design 1.1)1.The switch is closed which allows on-line(prenominal) to flow. The current flows thought the shut out, which is given Kirhhoffs voltage law.Note The end was at rest so eind = 0 I = VB-eind = VB/R R R2.While this current flows thu the there is a magnetic wring, which provoke a effectiveness on the wires. produce = i/B3. The bar allow for accelerate. When the the velocity of the bar increase, the voltage appears across the bar decide = vBl4. Thus the increase voltage reduces the current flowing through the bar.I = VB-eind R5. The result of this action is that eventually the bar will earn a constant steady state speed where the net force on the bar is zero. This happen when eind has risen all the way up to relate the voltage of VB & I=0. At that time the bar will be moving at a speed given byVss= VB Bl6. The bar will continue to move forever unless some out-of-door force disturbs it.Line ar DC force back or Generatorii) Motor Operation (See Fig 1.2)Since the bar was initially at steady state, industry of the force Fload motion will result in a force on the bar in the direction opposite the direction of motion.Fnet = Fload Find The resulting acceleration a = Fed/m is negative, so the bar slows heap the voltage eind=v Bl falls, and so I=(VB eind)/R increaseThe bring on force Find = I lB increase until Find = Fload at a lower speed v.An amount of electrical power equal to eindi is now being converted to mechanical power equal to Findv and and the machine is acting as a motoriii) Generator Operation (See Fig 1.2)The concept of a generator is similar to the motor. When (Fig 1.2) moved rapidly it is a generator but when it move slowly it a motor. In a Generator a force is applied in direction of motion. straight the applied force will cause the bar to accelerate in the direction of motion and the velocity of the bar will increase as the velocity increase , eind = v Bl will increase and will be larger than the battery voltage VB.