MODULE 6 — 1-Phase Induction Motor
6.1 Double Revolving Field Theory
$$ \Phi(\theta, t) = \Phi_m \cos(\theta) \cos(\omega t) $$
$$ = \frac{\Phi_m}{2} \underbrace{\cos(\theta - \omega
t)}_{\text{Forward}}
+ \frac{\Phi_m}{2} \underbrace{\cos(\theta + \omega t)}_{\text{Backward}} $$
A pulsating single-phase field is mathematically equivalent to two fields of half magnitude rotating in opposite directions.
6.2 Torque-Speed Curve
$$ s_f = s, \quad s_b = 2 - s $$
$$ T_{net} = T_f - T_b $$
At standstill (s=1), $T_f = T_b$ ∴ Net Torque = 0.
6.3 Starting Methods
$$ \alpha \approx 30^\circ $$
High R, Low X in auxiliary winding.