Elementary TwoPole Motor ECE 442 Power Electronics 1

Elementary Two-Pole Motor ECE 442 Power Electronics 1

Elementary Two-Pole Generator ECE 442 Power Electronics 2

Voltage induced in the coil, e • Flux through the coil window is sinusoidal • Φ = Φmaxsin(ωt) • • • Voltage induced in coil, e e = N(dΦ/dt) e = NωΦmaxcos(ωt) Emax = ωNΦmax Emax = 2πf. NΦmax Erms = 4. 44 f. NΦmax ECE 442 Power Electronics 3

Directions of induced voltage and current • Develop CCW countertorque • “Bunching” must occur at the top of coil side B and the bottom of coil side A • Coil current is CCW as viewed from south pole ECE 442 Power Electronics 4

Basic DC Generator Separately Excited Shunt Generator ECE 442 Power Electronics 5

ECE 442 Power Electronics 6

Generator Action • Permanent-magnet field • One-turn armature • Drive so that Ea>Ebat • Current Ia flows to charge Ebat ECE 442 Power Electronics 7

From a Circuit Point-of-View • “Generate” voltage Ea • When supplying current, the machine develops a “countertorque” in opposition to the driving torque ECE 442 Power Electronics 8

Motor Action • “Uncouple” the Prime Mover • Eventually, Ea will decrease so that Ea<Ebat • Ia flows as shown • Armature turns in the same direction ECE 442 Power Electronics 9

From a Circuit Point-Of-View • Counter-emf, Ea, is induced, opposing the driving voltage Ebat • Machine develops a driving torque ECE 442 Power Electronics 10