(SEM V) THEORY EXAMINATION 2022-23 INDUSTRIAL ELECTRONICS

SECTION A – Short Answer Type Questions (2 Marks each)

(a) Differentiate Between Normal and Power MOSFET.

Conclusion:
Power MOSFETs are specially designed to handle high power and voltage in industrial circuits while maintaining good switching speed and thermal performance.

(b) What is a Transducer?

A transducer is a device that converts one form of energy into another, especially non-electrical quantities into electrical signals for measurement or control.

Types of Transducers:

Active Transducers: Generate their own electrical output (e.g., thermocouple, piezoelectric sensor).

Passive Transducers: Require external power for signal conversion (e.g., LVDT, strain gauge).

Applications:
Used in automation, robotics, pressure and temperature measurement, and industrial process control.

SECTION B – Long Answer Type Questions (10 Marks each)

(a) Describe the Structure and Working of an IGBT with Neat Diagram.

Structure:
An Insulated Gate Bipolar Transistor (IGBT) combines the characteristics of MOSFET (high input impedance) and BJT (low on-state voltage drop).
It has four layers (P+, N−, P, N+) forming a PNPN structure controlled by an insulated gate.

Working Principle:

When gate voltage (Vge) > threshold, electrons flow through MOSFET channel from emitter to collector, turning the device ON.

The BJT section amplifies current, reducing conduction losses.

When gate voltage = 0, channel closes, and device turns OFF.

Advantages:

High current and voltage capacity.                   Low switching losses.

Simple gate drive requirements.

Applications:
Used in inverters, SMPS, induction heating, and motor drives.

(b) What is SMPS? Explain Its Block Diagram and Working.

Definition:
SMPS (Switched Mode Power Supply) converts electrical power efficiently using high-frequency switching devices like MOSFETs or IGBTs.

Block Diagram:

AC Input & Rectifier: Converts AC to DC.                           Filter: Removes ripples.

Switching Section: Converts DC to high-frequency AC.     Transformer: Provides isolation and voltage conversion.

Rectifier & Filter: Converts HF AC back to smooth DC output.

Feedback Control: Maintains stable output voltage.

Advantages:

High efficiency (up to 90%).       Compact size and lightweight.             Wide input voltage range.

Applications: Computers, communication devices, industrial control circuits.

SECTION C – Very Long Answer Type Questions (10 Marks each)

(a) Describe the Switching Characteristics of a Power Transistor.

Switching Characteristics:
A power transistor acts as an electronic switch in converter and inverter circuits. Its switching process has 
three intervals:

Turn-On Process:

Delay time (td): Time for base current to rise.

Rise time (tr): Time for collector current to reach maximum and voltage to fall.

Turn-Off Process:

Storage time (ts): Time to remove stored charge from base.

Fall time (tf): Collector current falls to zero.

Graph:
A plot of collector current (Ic) and collector-emitter voltage (Vce) against time shows the switching delays.

Importance:

Determines switching frequency and efficiency.

Affects power losses and heat dissipation.

Conclusion:
Fast-switching transistors improve performance in high-speed switching circuits like SMPS and converters.

(b) Define Different Types of Industrial Robots and Their Applications.

Definition:
An industrial robot is an automatically controlled, reprogrammable, multipurpose manipulator used in manufacturing and industrial processes.

Types of Industrial Robots:

Cartesian Robots:             Linear motion along X, Y, Z axes.

Used in CNC machines and pick-and-place operations.

Cylindrical Robots:

Rotary motion at the base and linear motion along the arm.

Used for assembly and handling operations.

SCARA Robots (Selective Compliance Assembly Robot Arm):

Ideal for assembly and material handling.                        High speed with horizontal reach.

Articulated Robots:

Multi-jointed arms with rotary joints.                               Used for welding, painting, and inspection.

Delta (Parallel) Robots:

Lightweight arms for high-speed tasks like packaging.

Applications:

Automotive welding and painting.                                   Electronics assembly.

Material handling and quality inspection.

Conclusion:
Industrial robots improve efficiency, precision, safety, and productivity in automation systems.