Motors Equivalent Model Filippas 2016 Equivalent model Node

Motors: Equivalent Model Filippas 2016

Equivalent model Node A Equivalen t to Node B

Motor in a circuit Going around the loop: The circuit is comprised of the voltage source and the motor. DC voltage source: rise : +V Set up KVL in the one loop – taking into account the equivalent circuit of the motor. Ammeter: zero voltage drop Resistor: voltage drop consistent with the direction of the current : VR + - Back-emf voltage: drop : -Vemf + KVL -

Motor in a circuit From previous: I Ohm’s law + VR - In lab, you use the ammeter to measure the current. You also know the value of the source voltage, V. Solve for Vemf:

Motor in a circuit I + VR -

Varying magnetic flux F I B I F perp F F Side view No field lines go through surface area of coil. F B F perp

Induced voltage So:

Power and efficiency Power dissipator “Useful” power Power generator How do we calculate power in electrical systems?

Power I I + V This is the picture of a power dissipator. + V This is the picture of a power generator.

Power and efficiency Power dissipator “Useful” power – power dissipated Power generator

Power and efficiency Power dissipator “Useful” power – power dissipated Power generator