|1 Crore+ students have signed up on EduRev. Have you?|
Identify the below given circuit.
It is a three-phase bridge type inverter. As SCRs are used as the switching device, it is called as a thyristor inverter.
The below given inverter circuit is a __ step inverter.
The three-phase bridge type is a 6-step inverter. That means, the firing changes from one SCR to another 6 times per cycle.
In inverters, to make the supply voltage constant
A large C connected across the input terminal keep the supply voltage from altering.
In the figure given below, for 180° mode of operation if T1 is fired at 0°. Then SCRs T3 and T5 should be fired at _________ and _________ respectively.
T1-T4 form the first pair. T3-T6 form the second pair, and like-wise. For the 180° mode, each SCR conducts for 180°, but the groups of SCRs lag the prior group by an angle of 120°. e.g. If T1 is fired at 0 then T3 must be fired at an angle of 0 + 120° and T5 at 120 + 120 = 240°.
_________ SCRs conduct from 300° to 360°.
Each step consists of 60°. 300° to 360° will be step VI.
A three-phase bridge inverter requires minimum of _______ switching devices.
It requires a min. 6 devices, 2 in each leg. Switching devices could be anything BJT, MOSFET or an IGBT. SCRs are used when very high power ratings are required.
In the three-phase bridge inverter, each step consists of
It is a 6 step inverter. Hence, 360/6 = 60°. This means that the SCRs are gated every 60° in proper sequence.
In the 180° mode VSI, ___________ devices conduct at a time.
Three devices conduct at a time. One from the upper pair and two from the lower pair or vice-versa.
For a three phase bridge inverter in the 180° mode, ___________ devices are conducting from 120° to 180°.
Each step consists of 60°. 120° to 180° will be step III.
The diodes D4 and D1 will conduct from
This will depend on the nature on the load, which is not mentioned in the above problem.