In a B-2 type full controlled bridge convertera)one SCR conducts at a ...
B-2 is the bridge type controller, in which 2 devices conduct at a time. One acting as the current supplying path and other acts as a return path.
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In a B-2 type full controlled bridge convertera)one SCR conducts at a ...
Introduction:
In a B-2 type full controlled bridge converter, there are four thyristors (SCRs) connected in the bridge configuration. The converter is used to convert a fixed DC voltage into a variable DC voltage. It is widely used in various industrial applications, such as adjustable speed drives, battery chargers, and power supplies.
Working Principle:
The converter operates by using the principle of pulse width modulation (PWM). It converts the fixed DC voltage into variable DC voltage by adjusting the pulse width of the applied voltage. The switching operation of the thyristors is controlled by firing pulses generated by a control circuit.
Conduction Modes:
The conduction of the thyristors in the bridge converter can be divided into four modes, based on the combination of conducting and non-conducting thyristors. These modes are as follows:
1. Mode 1: In this mode, thyristor T1 and T2 are conducting, while T3 and T4 are non-conducting. The positive terminal of the input DC voltage is connected to the load, and the negative terminal is connected to the common terminal of T3 and T4. The load voltage is positive in this mode.
2. Mode 2: In this mode, thyristor T3 and T4 are conducting, while T1 and T2 are non-conducting. The negative terminal of the input DC voltage is connected to the load, and the positive terminal is connected to the common terminal of T1 and T2. The load voltage is negative in this mode.
3. Mode 3: In this mode, thyristor T2 and T3 are conducting, while T1 and T4 are non-conducting. The positive terminal of the input DC voltage is connected to the load, and the negative terminal is connected to the common terminal of T1 and T4. The load voltage is negative in this mode.
4. Mode 4: In this mode, thyristor T1 and T4 are conducting, while T2 and T3 are non-conducting. The negative terminal of the input DC voltage is connected to the load, and the positive terminal is connected to the common terminal of T2 and T3. The load voltage is positive in this mode.
Answer:
In a B-2 type full controlled bridge converter, two SCRs conduct at a time. This can be observed from the above-mentioned conduction modes. In each mode, two thyristors are conducting, while the other two are non-conducting. Therefore, option 'B' is the correct answer.
It is important to mention that the firing pulses are generated based on the required output voltage, which determines the conduction mode of the thyristors. By controlling the firing angle, the average output voltage can be varied and hence the speed or intensity of the load can be controlled.
Additionally, it is worth noting that the B-2 type full controlled bridge converter offers better performance compared to other types of converters, as it allows bidirectional power flow and provides a smooth output voltage waveform.
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