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Single phase full wave controlled converter

Single phase full wave controlled converter

 

The circuit arrangement of a single-phase full converter is shown in Figure 1(a) with a highly inductive load so that the load current is continuous and ripple-free.

Single phase full wave controlled converter

 

During the positive half-cycle, thyristors T1 and T2 are forward biased; and when these two thyristors are fired simultaneously at ωt = α, the load is connected to the input supply through T1 and T2. Due to the inductive load, thyristors T1 and T2 continue to conduct beyond ωt = π, even though the input voltage is already negative.

ধনাত্মক অর্ধ-চক্রের সময়, থাইরিস্টার T1 এবং T2 ফরওয়ার্ড বায়াসড হয় এবং যখন এই দুটি থাইরিস্টার ωt = α তে একই সাথে ফায়ারিং করা হয়, তখন লোড T1 এবং T2 এর মাধ্যমে ইনপুট সরবরাহের সাথে সংযুক্ত থাকে। ইনডাক্টিভ লোডের কারণে, থাইরিস্টার T1 এবং T2 ωt = π এর বাইরেও কন্ডাকশন করবে , যদিও ইনপুট ভোল্টেজ ইতিমধ্যেই ঋণাত্মক হবে।

During the negative half-cycle of the input voltage, thyristors T3 and T4 are forward biased; and firing of thyristors T3 and T4 applies the supply voltage across thyristors T1 and T2 as reverse blocking voltage.

 T1 and T2 are turned off due to line or natural commutation and the load current is transferred from T1 and T2 to T3 and T4. Figure 1(b) shows the waveforms for input voltage and output voltage.

During the period from α to π, the input voltage vs, and the input current is, are positive; and the power flows from the supply to the load. The converter is said to be operated in rectification mode.

During the period from π to π +α, the input voltage vs, is negative and the input current is, is positive; and reverse power flows from the load to the supply. The converter is said to be operated in inversion mode.

This converter is extensively used in industrial applications up to 15 kW (1). Depending on the value of a, the average output voltage could be either positive or negative and it provides a two-quadrant operation.

 

Single phase full wave controlled converter

Single phase full wave controlled converter

 

Single phase full wave controlled converter

 

Read: Working principle of half wave controlled converter

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