A single phase fully controlled converter bridge is used

A single phase fully controlled converter bridge is used for electrical braking of a separately excited dc motor. The dc motor load is represented by an equivalent circuit as shown in the figure given below.

Assume that the load inductance is sufficient to ensure continuous and ripple free load current. The firing angle of the bridge for a load current of I₀ = 10 A will be

For continuous conduction Average load current (by KVL),

V_t – 2I_a + 150 = 0

∴ I =	V_t + 150	= 10 A
	2

⇒ V_t + 150 = 20

⇒	2 V_m	cos α = -130
	π

⇒	2 × √2 × 230 × cos α	= -130
	π

⇒ α = 129°