Basic DC Generator Separately Excited Shunt Generator If
Basic DC Generator Separately Excited Shunt Generator
If the Rheostat resistance is reduced, If increases, Φp increases, Ea increases, as shown in the “Magnetization” Curve
Operating Point Ebat = If(Rf +Rrheo) looks like y=mx + b Superimpose on the Magnetization curve
Operating Point (continued) Intersection with the Magnetization curve yields the operating point
Generator-to-Motor Transition • Permanent-magnet field • One-turn armature • Drive so that Ea>Ebat • Current Ia flows to charge Ebat
From a Circuit Point-of-View • “Generate” voltage Ea • When supplying current, the machine develops a “countertorque” in opposition to the driving torque
Motor-to-Generator Transition • “Uncouple” the Prime Mover • Eventually, Ea will decrease so that Ea<Ebat • Ia flows as shown • Armature turns in the same direction
From a Circuit Point-Of-View • Counter-emf, Ea, is induced, opposing the driving voltage Ebat • Machine develops a driving torque
Reversing Direction Method 1 Reverse the Armature Current
Reversing Direction – Method 2 Reverse the Direction of the Field
Basic DC Motor – Shunt Motor
Characteristics of a Shunt Motor • Shunt field provides the pole flux • Power in the field is independent of the LOADing • Generate counter-emf in the armature
- Slides: 13