The what is ac to dc converter with suitable examples and sketches are discuss here advanced. what is ac to dc converter is needed to read.
Semi-controlled converter is a hybrid between uncontrolled and fullycontrolled converters. It is also known as “semi-converter”.
Semi-converter offers variable positive DC output voltage only. Regeneration or inverter mode operation is not available
Single-phase Semi-converter with inductive load
In a semi-converter, thyristor conduction is delayed by angle α but diode conduction begins at their default points (i.e. zero delay-angle). For continuous load current (which we assumed), at any time, a thyristor from the upper-half and a diode from the lower-half must conduct the load current 𝐼𝑜, i.e. last two active devices conduct at any point of time.
By varying 𝛼 over 0° to 180°, we can adjust 𝑉 𝑜 𝑚𝑒𝑎𝑛 between 8𝑉𝑝 𝜋 and 0.
In 𝐼𝑠waveform, front-end of current pulse (in each half-cycle) is moved to the right by 𝛼 but rear-end is fixed. For a given delay angle 𝛼, the width of current pulse is 𝜋 −𝛼 .
Note: We assumed continuous load current for all delay angles. In reality, at higher delay-angles, load current becomes discontinuous. Then the input current will be different.
There are some other implementations of the single-phase semi-converter, all offering the same input-output performances.
Alternative Implementation – 1
Alternative Implementation – 2
Alternative Implementation – 3
Which implementation we want to select is partly our own preference and partly technical /operational requirements.
Thyristors (also diodes) are available as individual devices or multiple devices. Twin devices are available in common-cathode, common-anode or bridgedleg options. Selection of the converter configuration may depend on the type of available devices.
Technically, common-cathode configuration of standard implementation eases the assembly of two gate drive circuits sharing the cathodes. Threeleg implementation gives the choice between semi-converter and fullconverter during operation by making diode D5 in or out.
Self Attempt what is ac to dc converter
Draw the output voltage and input current waveforms for the other three configurations of 1-phase semi-converter, and indicate the devices conducting in different intervals of the cycle.
The what is ac to dc converter with suitable examples and sketches are discuss here advanced. It is needed to read.