Technical Articles

Dynamic Characteristics of SCR The static characteristics gives no indication as to the speed at which the SCR is capable of being switched from the forward blocking voltage to the conducting state and vice-versa. However, the transition…
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Two-Transistor Model of SCR (Two Transistor Analogy) The operation of an SCR can also be explained very simply by considering it in terms of two transistors. This is known as the two-transistor analogy of the SCR. The SCR can be…
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Turn-Off Methods of A Thyristor The term commutation basically means the transfer of current from one path to another. In thyristor circuits, this term is used to describe process of transferring current from one thyristor to another. As…
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A thyristor can be switched from a nonconducting state to a conducting state in several ways described as follows. 1.9.1 Forward Voltage Triggering When anode-to-cathode forward voltage is increased with gate circuit open, the reverse…
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An elementary circuit diagram for obtaining static V-I characteristics of a thyristor is shown in Figure 17. Here, the anode and cathode are connected to the main source through a load. The gate and cathode are fed from another source Eg.…
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As we know that once an SCR is turned ON by the gate signal, the gate loses control and it can be brought back to the blocking state only by reducing the forward current to a level below that of the holding current. This is the serious…
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Figure shows the turn on switching characteristics of IGBT. The delay time td(on) is the required time to fall the collector-emitter voltage from VCE to 0.9VCE where VCE is the initial collector emitter voltage. The delay time td(on) is…
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The V-I characteristics of the n-channel IGBT is shown in Figure 14(a). In the forward direction they are like those of the logic level bipolar transistor, the only difference here is that the controlling parameter is the gate-to-source…
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Another development in power MOS technology is the insulated gate bipolar transistor (IGBT). This device combines the best qualities of power MOSFET and bipolar transistor. It has an input characteristic of a MOSFET and an output…
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Figure 12(a) shows a steady state switching circuit of a power MOSFET. When a pulse input voltage is applied to the gate of power MOSFET, the device will be turn-on if the gate to source voltage VGS is greater than threshold voltage…
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