The controlling parameter in IGBT is the

Question

Examoogle · Accepted Answer

$V_{GE}$

Explanation: The Insulated Gate Bipolar Transistor (IGBT) is a voltage-controlled device. The output current ($I_C$) is controlled by the input voltage applied between the Gate and Emitter terminals ($V_{GE}$).

Working Principle: The IGBT structure combines an input MOSFET with an output Bipolar Junction Transistor. Applying a gate-to-emitter voltage $V_{GE}$ exceeding the threshold voltage $V_{GE(th)}$ creates an inversion layer in the MOSFET structure, which provides the base current to drive the internal PNP transistor, thereby controlling the collector current $I_C$.

Key Formulas: $I_C = g_m (V_{GE} - V_{GE(th)})$ — simplified transconductance relationship; $V_{GE} > V_{GE(th)}$ — condition for turn-on

Key Points: IGBT is a hybrid device combining MOSFET gate and BJT collector-emitter path.; High input impedance is inherited from the MOSFET structure.; Low on-state voltage drop is inherited from the BJT structure.; It is primarily used in medium to high power applications like inverters and SMPS.

Advantages: High input impedance leads to low gate drive power requirements; Lower switching losses compared to traditional BJTs; Excellent conduction characteristics at high current

Disadvantages: Possibility of latch-up due to internal parasitic thyristor structure; Slower turn-off time compared to power MOSFETs due to minority carrier storage

Applications: Variable Frequency Drives (VFDs); Electric Vehicles (EV) traction inverters; Uninterruptible Power Supplies (UPS)

Additional Info: IGBTs do not require a continuous gate current like BJTs.. Option A ($I_G$) is incorrect because the gate draws negligible current. Option C ($I_C$) is the controlled quantity, not the controlling parameter. Option D ($V_{CE}$) is the output voltage drop.

Answer: B is correct — The IGBT is a voltage-controlled device where the gate-to-emitter voltage $V_{GE}$ determines the conduction state.

Exam Tip: Always remember: MOSFETs and IGBTs are voltage-controlled, while BJTs and Thyristors (SCRs) are current-controlled.

Related Questions

Discussion (0)