Research on the Brushless Excitation System with Linear Current Amplifier Characteristics

Table 1

Three operating modals.

Working modes	Commutation angle	Delay angle	Electrical characteristics	External characteristics	Condition	Req
I	γ < π/3	α′ = 0	Conduction and commutation		XR ≤ π/9	3Xc/π
II	γ = π/3	0 < α′ < π/3	Commutation (two-phase short-circuit)		π/9 < XR≤π/3	3Xc/π∼9Xc/π
III	π/3 < γ ≤ 2π/3	α' = π/3	Commutation (three-phase short-circuit)		π/3 < XR	9Xc/π