Question 1(a) [3 marks]

Draw symbol and construction of SCR. Also write down applications of SCR.

Answer:

Symbol and Construction of SCR:

    Anode (A)
       |
       v
       _
      | |
      | |
  G ->|_|  
      | |
      |_|
       |
       v
   Cathode (K)

Construction:

graph LR
    A[Anode] --- P1[P-Layer]
    P1 --- N1[N-Layer]
    N1 --- P2[P-Layer]
    P2 --- N2[N-Layer]
    N2 --- K[Cathode]
    G[Gate] --- P2

Applications of SCR:

Power control: AC/DC power regulators
Motor drives: Speed control of motors
Lighting control: Dimmer circuits
Inverters: DC to AC conversion

Mnemonic: "PALS" - Power control, Appliance control, Lighting systems, Speed regulators

Question 1(b) [4 marks]

State full form of (i) SCS (ii) LASCR (iii) MCT (iv) PUT.

Answer:

Device	Full Form
SCS	Silicon Controlled Switch
LASCR	Light Activated Silicon Controlled Rectifier
MCT	MOS Controlled Thyristor
PUT	Programmable Unijunction Transistor

Mnemonic: "SLaMP" - Silicon controlled switch, Light activated SCR, MOS controlled thyristor, Programmable UJT

Question 1(c) [7 marks]

Draw and explain V-I characteristics of TRIAC. Also write down applications of TRIAC.

Answer:

V-I Characteristics of TRIAC:

graph LR
    subgraph "V-I Characteristics"
    style V-I fill:#f9f9f9,stroke:#333,stroke-width:1px

    MT2((MT2)) --- O[O]
    O --- MT1((MT1))
    
    V1[V] --- I1[I]
    
    G[Gate Triggering]
    
    quad1[I quadrant] --- quad3[III quadrant]
    breakover1[Breakover voltage +Vbo] --- breakover2[Breakover voltage -Vbo]
    
    holding1[Holding current +Ih] --- holding2[Holding current -Ih]
    end

TRIAC V-I characteristics explanation:

Bidirectional device: Conducts in both directions
Quadrant operation: Works in 1st and 3rd quadrants
Breakover voltage: Starts conducting when voltage exceeds ±Vbo
Holding current: Minimum current to maintain conduction state
Gate triggering: Can be triggered with positive/negative gate voltage

Applications of TRIAC:

AC power control: Lamp dimmers, heater controls
Motor speed control: AC motor regulators
Fan regulators: Domestic fan speed control
Light dimmers: Adjustable lighting systems

Mnemonic: "HALF" - Heaters, AC controls, Lighting systems, Fan regulators

Question 1(c) OR [7 marks]

Explain construction and working of IGBT in detail.

Answer:

IGBT Construction and Working:

graph LR
    G[Gate] --- E[Emitter]
    E --- N+[N+ Layer]
    N+ --- P[P Layer]
    P --- N-[N- Drift Region]
    N- --- N+B[N+ Buffer Layer]
    N+B --- C[Collector]

Construction details:

Three-terminal device: Gate, Emitter, Collector
Multilayer structure: N+, P, N-, N+ buffer, P+ substrate
Hybrid device: Combines MOSFET input with BJT output characteristics

Working principle:

Gate control: Positive voltage at gate forms inversion layer in P-region
Channel formation: Electrons flow from N+ emitter to N- drift region
Conductivity modulation: P-N- junction injects holes, lowering resistance
Turn-off process: Removing gate voltage stops electron flow

Advantages of IGBT:

High input impedance: Easy voltage control
Low conduction losses: Efficient power handling
Fast switching: Good for high-frequency applications

Mnemonic: "GIVE" - Gate controlled, Input high impedance, Voltage driven, Efficient conduction

Question 2(a) [3 marks]

Discuss relaxation oscillator circuit using UJT.

Answer:

UJT Relaxation Oscillator:

graph LR
    VCC[VCC] --- R1[R1] --- E[Emitter]
    E --- C[Capacitor] --- GND[GND]
    E --- UJT[UJT]
    UJT --- B1[Base 1] --- R2[R2] --- GND
    UJT --- B2[Base 2] --- R3[R3] --- VCC
    B1 --- Output[Output]

Working principle:

Capacitor charging: C charges through R1 until reaching UJT firing voltage
UJT fires: When emitter voltage reaches peak point voltage
Discharge cycle: Capacitor discharges through emitter-base1 junction
Oscillation: Process repeats creating sawtooth waveform

Mnemonic: "CROP" - Capacitor charges, Reaches threshold, Oscillates, Produces sawtooth

Question 2(b) [4 marks]

Discuss the triggering methods of SCR.

Answer:

Triggering Method	Working Principle
Gate Triggering	Applying positive voltage between gate and cathode
Thermal Triggering	Temperature increase reduces breakover voltage
Light Triggering	Photons create electron-hole pairs in LASCR
dv/dt Triggering	Rapid voltage rise across SCR causes capacitive current
Breakover Triggering	Voltage exceeds breakover voltage without gate signal

Key points:

Gate triggering: Most common method
Light triggering: Used in opto-isolators
dv/dt triggering: Often undesirable, requiring snubber circuits

Mnemonic: "GLTDB" - Gate, Light, Thermal, dv/dt, Breakover

Question 2(c) [7 marks]

Explain class A type commutation method.

Answer:

Class A Commutation (Self-commutation by LC circuit):

graph LR
    DC_Source[DC Source] --- SCR[SCR] --- Load[Load]
    SCR --- L[Inductor] --- C[Capacitor]
    C --- SW[Switch] --- DC_Source

Working principle:

Initial state: SCR conducting, capacitor charged with polarity (+) on right
Commutation start: When switch SW closed
Resonant circuit: LC circuit forms resonant path
Reverse current: Capacitor discharge creates reverse current through SCR
Turn-off: SCR turns off when current falls below holding current
Recharging: Capacitor recharges with opposite polarity

Applications:

Inverter circuits: DC to AC conversion
Chopper circuits: DC to DC conversion

Mnemonic: "SCCRRT" - Switch closes, Capacitor discharges, Current reverses, SCR turns off, Recharging begins, Turn-off complete

Question 2(a) OR [3 marks]

State full form of GTO and draw the structure of GTO.

Answer:

Full form of GTO: Gate Turn-Off Thyristor

Structure of GTO:

graph LR
    A[Anode] --- P1[P+ Anode Layer]
    P1 --- N[N Base Layer]
    N --- P2[P Base Layer]
    P2 --- N2[N+ Cathode Layer]
    N2 --- K[Cathode]
    G[Gate] --- P2

Mnemonic: "PANG" - P-anode, And, N-base, Gate-controlled thyristor

Question 2(b) OR [4 marks]

Discuss the design and requirement of snubber circuit for SCR.

Answer:

Snubber Circuit for SCR:

graph LR
    SCR[SCR] --- R[Resistor] --- C[Capacitor]
    C --- SCR

Design requirements:

Resistor selection: Limits discharge current of capacitor
Capacitor selection: Controls rate of voltage rise (dv/dt)
RC time constant: Determines response time

Purpose of snubber circuit:

dv/dt protection: Prevents false triggering due to rapid voltage changes
Voltage spike suppression: Absorbs inductive voltage spikes
Transient protection: Protects SCR during switching

Mnemonic: "RAPE" - Resistor And capacitor Protect against Excessive voltage rise

Question 2(c) OR [7 marks]

Explain class C type commutation method.

Answer:

Class C Commutation (Complementary commutation):

graph LR
    DC_Source[DC Source] --- SCR1[SCR1] --- Load1[Load 1]
    DC_Source --- SCR2[SCR2] --- Load2[Load 2]
    SCR1 --- SCR2

Working principle:

Initial state: SCR1 conducting, SCR2 off
Commutation start: SCR2 is triggered
Load transfer: Current transfers from SCR1 to SCR2
Voltage reversal: Voltage across SCR1 becomes negative
Turn-off: SCR1 turns off as current falls below holding current
Alternating operation: SCR1 and SCR2 conduct alternatively

Applications:

Inverter circuits: Used in bridge inverters
Dual load systems: Where alternate operation is required

Mnemonic: "TACTOR" - Triggering Alternate SCRs Creates Turn-Off and Reversal

Question 3(a) [3 marks]

State the advantages of poly-phase rectifier over single phase rectifier.

Answer:

Advantage	Description
Higher efficiency	Lower power loss and better transformer utilization
Lower ripple factor	Smoother DC output requiring smaller filter components
Higher power handling	Can handle higher power levels than single phase
Better transformer utilization	Higher transformer utilization factor
Lower harmonic content	Reduced harmonic distortion in output

Mnemonic: "HELPS" - Higher efficiency, Even output, Lower ripple, Power handling better, Smaller filter

Question 3(b) [4 marks]

Draw and explain the circuit of single phase Half Wave rectifier. Draw the waveforms.

Answer:

Single Phase Half Wave Rectifier:

graph LR
    AC[AC Supply] --- D[Diode] --- R[Load Resistor]
    R --- AC

Waveform:

    Voltage
      ^
      |     /\      /\      /\
      |    /  \    /  \    /  \
      |---/----\--/----\--/----\----> Time
      |         \       \       \
      |          \       \       \
      |
   Input AC
   
    Voltage
      ^
      |     /\      /\      /\
      |    /  \    /  \    /  \
      |---/----\--/----\--/----\----> Time
      |    
      |    
      |
   Output DC (Pulsating)

Working principle:

Forward bias: Diode conducts during positive half-cycle
Reverse bias: Diode blocks current during negative half-cycle
Output: Pulsating DC with high ripple factor
Frequency: Output frequency same as input frequency

Mnemonic: "PROF" - Positive half conducts, Reverse half blocks, Output is pulsating, Frequency unchanged

Question 3(c) [7 marks]

List all types of Inverters. Out of that explain single phase full bridge Inverter.

Answer:

Types of Inverters:

Based on circuit: Series, Parallel, Bridge
Based on phases: Single-phase, Three-phase
Based on output: Square wave, Modified sine wave, Pure sine wave
Based on commutation: SCR-based, Transistor-based

Single Phase Full Bridge Inverter:

graph LR
    DC[DC Source] --- S1[Switch S1] --- S2[Switch S2] --- DC
    S1 --- Load[Load] --- S3[Switch S3]
    S2 --- Load
    S3 --- S4[Switch S4] --- DC

Working principle:

First half-cycle: S1 and S4 ON, S2 and S3 OFF
Second half-cycle: S2 and S3 ON, S1 and S4 OFF
Output waveform: AC square wave across load
Control method: Gate signals to switches with 180° phase shift

Advantages:

Higher output power: Twice the output of half bridge
Better voltage utilization: Full DC bus voltage across load
Lower current rating: Each switch carries only load current

Mnemonic: "SOAP" - Switches Operate Alternately in Pairs

Question 3(a) OR [3 marks]

Compare UPS and SMPS.

Answer:

Parameter	UPS (Uninterruptible Power Supply)	SMPS (Switched Mode Power Supply)
Primary function	Provides backup power during outages	Converts AC to regulated DC
Battery backup	Contains batteries for backup	No battery backup
Output	AC output (typically)	DC output (typically)
Efficiency	Lower (70-80%)	Higher (80-95%)
Size	Larger and heavier	Compact and lightweight
Applications	Computers, servers, critical equipment	Electronic devices, chargers

Mnemonic: "BBOSS" - Backup Battery Only in UPS, Small Size in SMPS

Question 3(b) OR [4 marks]

Draw and explain the circuit of three phase Half Wave rectifier. Draw the waveforms.

Answer:

Three Phase Half Wave Rectifier:

graph LR
    R[R Phase] --- D1[Diode D1] --- Load[Load]
    Y[Y Phase] --- D2[Diode D2] --- Load
    B[B Phase] --- D3[Diode D3] --- Load
    Load --- N[Neutral]

Waveform:

     Voltage
       ^
       |   
       |    /\    /\    /\    /\    /\    /\
       |   /  \  /  \  /  \  /  \  /  \  /  \
       |--/----\/----\/----\/----\/----\/----\--> Time
       |   R    Y    B    R    Y    B    R
       |   
    Input (Three phase)
    
     Voltage
       ^
       |   
       |    /\    /\    /\    /\    /\    /\
       |   /  \  /  \  /  \  /  \  /  \  /  \
       |--/----\/----\/----\/----\/----\/----\--> Time
       |      
       |   
    Output DC (Less ripple)

Working principle:

Conduction sequence: Each diode conducts when its phase voltage is highest
Conduction angle: Each diode conducts for 120°
Output ripple: 3 pulses per cycle, lower ripple than single phase
Ripple frequency: 3 times the input frequency

Mnemonic: "CROP" - Conduction of 120°, Ripple reduced, Output smoother, Pulses tripled

Question 3(c) OR [7 marks]

Define chopper. With the help of circuit diagram explain class D chopper.

Answer:

Definition of Chopper: A chopper is a DC to DC converter that converts fixed DC input voltage to variable DC output voltage using high-frequency switching.

Class D Chopper (Two-quadrant chopper):

graph LR
    VS[DC Source] --- S1[Switch S1] --- L[Inductor]
    L --- Load[Load] --- VS
    Load --- D1[Diode D1] --- S1
    Load --- S2[Switch S2] --- D2[Diode D2] --- VS

Working principle:

First quadrant operation (forward motoring):
- S1 ON, S2 OFF: Energy flows from source to load
- S1 OFF, S2 OFF: Current freewheels through D2
Second quadrant operation (forward regeneration):
- S1 OFF, S2 ON: Energy flows from load to source
- S1 OFF, S2 OFF: Current freewheels through D1

Applications:

DC motor drives: Providing forward motoring and regenerative braking
Battery charging: Controlling charging current
Renewable energy: Interfacing with solar panels

Mnemonic: "FRED" - Forward motoring, Regenerative braking, Energy flow control, Dual quadrant operation

Question 4(a) [3 marks]

Describe the use of SCR as a static switch.

Answer:

SCR as Static Switch:

graph LR
    VS[Supply] --- SCR[SCR] --- Load[Load]
    GC[Gate Control] --- SCR

Key features:

No moving parts: Purely electronic switching
Fast switching: Microsecond response time
High reliability: Longer lifetime than mechanical switches
Controlled turn-on: Precise control via gate signal

Advantages over mechanical switches:

No arcing: No contact bounce or wear
Silent operation: No mechanical noise
EMI reduction: Less electromagnetic interference

Mnemonic: "FANS" - Fast switching, Arc-free operation, No mechanical wear, Silent operation

Question 4(b) [4 marks]

Draw the circuit diagram of A.C. Power control using DIAC and TRIAC and explain its working.

Answer:

AC Power Control using DIAC and TRIAC:

graph LR
    AC[AC Supply] --- TRIAC[TRIAC] --- Load[Load]
    AC --- R[Resistor] --- C[Capacitor] --- DIAC[DIAC] --- G[TRIAC Gate]
    G --- TRIAC

Working principle:

RC network: Controls firing angle by delaying gate pulse
Capacitor charging: C charges through R during each half-cycle
DIAC breakdown: When capacitor voltage reaches DIAC breakover voltage
TRIAC triggering: DIAC conducts and triggers TRIAC
Power control: Varying R changes firing angle and thus power delivered

Applications:

Light dimmers: Controlling brightness of lamps
Fan speed control: Regulating fan speed
Heater control: Adjusting heating elements

Mnemonic: "CRAFT" - Capacitor charges, Reaches breakover, Activates DIAC, Fires TRIAC, Transfers power

Question 4(c) [7 marks]

Explain the working principle of induction heating also write the applications of induction heating.

Answer:

Working Principle of Induction Heating:

graph LR
    Power[AC Power Supply] --- Inv[High Frequency Inverter]
    Inv --- Coil[Induction Coil]
    Coil --- Workpiece[Metal Workpiece]

    subgraph "Physical Process"
    Coil -.- Magnetic[Alternating Magnetic Field]
    Magnetic -.- Eddy[Eddy Currents]
    Eddy -.- Heat[Heat Generation]
    end

Working principle:

High-frequency current: Passes through induction coil
Electromagnetic induction: Creates alternating magnetic field
Eddy currents: Induced in workpiece
Resistance heating: Eddy currents generate heat due to resistance
Skin effect: Heat concentrated near surface
Non-contact heating: No physical contact between coil and workpiece

Applications of Induction Heating:

Metal heat treatment: Hardening, annealing, tempering
Metal melting: Foundry operations
Welding and brazing: Joining metal components
Forging: Heating before forming
Domestic cooking: Induction cooktops
Semiconductor processing: Crystal growth

Mnemonic: "MASTER" - Magnetic field, Alternating current, Surface heating, Temperature control, Eddy currents, Resistance heating

Question 4(a) OR [3 marks]

Explain working of photo relay circuit using LDR.

Answer:

Photo Relay Circuit using LDR:

graph LR
    VS[Supply] --- R1[Resistor R1] --- LDR[LDR]
    LDR --- GND[Ground]
    R1 --- B[Transistor Base]
    VS --- RC[Collector Resistor] --- C[Transistor Collector]
    C --- Relay[Relay Coil] --- GND
    E[Transistor Emitter] --- GND

Working principle:

Light-dependent resistor: Resistance decreases with increasing light
Voltage divider: LDR and R1 form voltage divider
Transistor switching: Base voltage controls transistor conduction
Relay operation: Transistor drives relay coil
Threshold adjustment: Can be set using variable resistor

Applications:

Automatic street lighting: Turns on lights at dusk
Day/night switching: Controls devices based on ambient light
Security systems: Light-activated alarms

Mnemonic: "LARK" - Light controls, Activates transistor, Relay switches, Keeps circuit automated

Question 4(b) OR [4 marks]

Explain the operation of timer circuit using 555 timer IC.

Answer:

555 Timer Circuit (Monostable):

graph TD
    VCC[+VCC] --- R[Resistor R] --- D8[Pin 8 VCC]
    D8 --- D4[Pin 4 Reset]
    D8 --- D7[Pin 7 Discharge]
    R --- D7
    D7 --- C[Capacitor C] --- GND[Ground]
    Trigger[Trigger Input] --- D2[Pin 2 Trigger]
    D3[Pin 3 Output] --- Output[Output]
    D1[Pin 1 GND] --- GND
    D5[Pin 5 Control] --- CC[Control Capacitor] --- GND
    D6[Pin 6 Threshold] --- D7

Working principle:

Trigger input: Active low trigger at pin 2
Timing components: R and C determine timing period (T = 1.1RC)
Output high: When triggered, output goes high
Capacitor charging: C charges through R
Threshold detection: When voltage reaches 2/3 VCC, output goes low
Timer reset: Circuit can be reset using pin 4

Applications:

Delay circuits: Creating time delays
Pulse generation: Generating precise pulses
Timing control: Sequential timing operations

Mnemonic: "TRACT" - Trigger activates, Resistor-capacitor timing, Accurate delay, Capacitor charges, Threshold detection

Question 4(c) OR [7 marks]

Explain the working principle of dielectric heating also write the applications of dielectric heating.

Answer:

Working Principle of Dielectric Heating:

graph LR
    RF[RF Generator] --- Electrodes[Electrodes]

    subgraph "Material Between Electrodes"
    Electrodes --- Electric[Alternating Electric Field]
    Electric --- Dipoles[Molecular Dipoles]
    Dipoles --- Oscillation[Dipole Oscillation]
    Oscillation --- Friction[Molecular Friction]
    Friction --- Heat[Heat Generation]
    end

Working principle:

High-frequency electric field: Applied between electrodes
Dielectric material: Placed between electrodes
Molecular polarization: Dipoles align with electric field
Field oscillation: Rapid reversal of field direction
Molecular friction: Dipoles rotate rapidly causing friction
Volumetric heating: Heat generated throughout material
Frequency range: Typically 10-100 MHz

Applications of Dielectric Heating:

Food processing: Baking, drying, pasteurization
Wood industry: Gluing, drying timber
Textile drying: Removing moisture from fabrics
Plastic welding: Joining thermoplastics
Medical applications: Therapeutic diathermy
Paper industry: Drying paper products

Mnemonic: "DIPOLE" - Dielectric material, Intense electric field, Polarization of molecules, Oscillation causes, Linkage of heat, Even heating throughout

Question 5(a) [3 marks]

Define AC drive. State applications of AC drives.

Answer:

Definition of AC Drive: An AC drive is an electronic device that controls the speed, torque, and direction of an AC motor by varying the frequency and voltage supplied to the motor.

Applications of AC Drives:

Application Area	Examples
Industrial	Conveyor systems, pumps, fans, compressors
HVAC	Blowers, cooling towers, air handling units
Water treatment	Pumps, mixers, aerators
Mining	Crushers, conveyors, pumps
Textile	Spinning machines, looms, winders
Material handling	Cranes, elevators, escalators

Mnemonic: "PITCHW" - Pumps, Industrial machinery, Textile machines, Conveyor systems, HVAC systems, Water treatment

Question 5(b) [4 marks]

Draw and explain any one method for speed control of DC shunt motor.

Answer:

Armature Voltage Control Method for DC Shunt Motor:

graph LR
    AC[AC Supply] --- B[Bridge Rectifier]
    B --- SCR[SCR] --- A[Armature]
    A --- B
    AC --- F[Field Circuit]
    F --- Field[Field Winding]
    GC[Gate Control] --- SCR

Working principle:

Constant field current: Field supply maintained constant
Variable armature voltage: Controlled by SCR
Speed equation: N ∝ (Vₐ - IₐRₐ)/Φ
Speed control: By changing armature voltage Vₐ
Torque control: Armature current controls torque

Advantages:

Wide speed range: Can achieve speeds below and above base speed
Smooth control: Continuous speed adjustment
High efficiency: Low power loss in control circuit

Mnemonic: "SAVE" - SCR controls, Armature voltage varies, Velocity changes, Efficient operation

Question 5(c) [7 marks]

Draw the block diagram of PLC and explain the function of each block.

Answer:

PLC Block Diagram:

graph TD
    PS[Power Supply] --- CPU[Central Processing Unit]
    CPU --- MEM[Memory]
    CPU --- INP[Input Module]
    CPU --- OUT[Output Module]
    CPU --- COM[Communication Module]
    INP --- Input[Input Devices]
    OUT --- Output[Output Devices]
    COM --- Network[Network/HMI]
    PROG[Programming Device] --- COM

Functions of each block:

Block	Function
Power Supply	Converts main AC supply to DC required for internal circuits
CPU	Executes program, processes I/O, performs calculations
Memory	Stores program, data, and I/O status (RAM, ROM, EEPROM)
Input Module	Interfaces with input devices, provides isolation, signal conditioning
Output Module	Drives output devices, provides isolation and protection
Communication Module	Connects PLC to networks, other PLCs, and programming devices
Programming Device	Used to develop, edit, and monitor PLC programs

Advantages of PLC:

Reliability: Solid-state components with high MTBF
Flexibility: Easily reprogrammable for different applications
Communication: Network capabilities for distributed control
Diagnostics: Built-in diagnostics and troubleshooting

Mnemonic: "PRIME-C" - Power supply, RAM/ROM memory, Input module, Microprocessor (CPU), Execution of program, Communication interface

Question 5(a) OR [3 marks]

State the applications of stepper motor.

Answer:

Application Area	Examples
Precision positioning	CNC machines, 3D printers, robotic arms
Office equipment	Printers, scanners, photocopiers
Medical devices	Surgical robots, fluid pumps, sample handlers
Automotive	Headlight adjustment, idle control, mirror control
Aerospace	Satellite positioning, antenna control
Consumer electronics	Cameras (focus/zoom), gaming controllers

Mnemonic: "POMAC" - Positioning systems, Office equipment, Medical devices, Automotive controls, Consumer electronics

Question 5(b) OR [4 marks]

Draw and explain the circuit to control speed of a DC series motor.

Answer:

Speed Control of DC Series Motor using SCR:

graph LR
    AC[AC Supply] --- B[Bridge Rectifier]
    B --- SCR[SCR] --- A[Armature]
    A --- SF[Series Field]
    SF --- B
    GC[Gate Control] --- SCR

Working principle:

Series connection: Field winding in series with armature
SCR control: Phase-controlled SCR regulates average voltage
Speed equation: N ∝ (V - I(Ra+Rf))/IΦ
Speed-torque relation: Non-linear relationship
Application: Used when high starting torque required

Advantages:

High starting torque: Ideal for traction applications
Simple control: Basic circuit design
Cost-effective: Fewer components than other methods

Mnemonic: "SCAT" - Series connection, Current controls flux, Average voltage controlled by SCR, Torque highest at low speeds

Question 5(c) OR [7 marks]

Discuss the BLDC motor in brief.

Answer:

BLDC Motor (Brushless DC Motor):

graph LR
    subgraph "BLDC Motor Construction"
    Stator[Stator with Windings]
    Rotor[Rotor with Permanent Magnets]
    Hall[Hall Sensors]
    end

    subgraph "Control System"
    Controller[Electronic Controller]
    Driver[Power Driver]
    Feedback[Position Feedback]
    end
    
    Controller --- Driver
    Driver --- Stator
    Hall --- Feedback
    Feedback --- Controller

Construction:

Stator: Contains windings (typically 3-phase)
Rotor: Permanent magnets on rotor
Position sensing: Hall effect sensors or encoders
Controller: Electronic commutation controller

Working principle:

Electronic commutation: Replaces mechanical brushes
Sequencing: Controller energizes stator coils in sequence
Position feedback: Hall sensors determine rotor position
Phase energizing: Proper phase energized based on rotor position

Advantages:

High efficiency: No brush friction losses
Low maintenance: No brush wear
Longer lifespan: Reliable operation
Better speed-torque characteristics: Flat curve
Low noise: Quiet operation
Better heat dissipation: Windings on stator

Applications:

Computer cooling fans: CPU/GPU coolers
Hard disk drives: Spindle motors
Electric vehicles: Propulsion systems
Drones: Propeller motors
Home appliances: Washing machines, refrigerators
Industrial automation: Precision control systems

Mnemonic: "COPPER" - Commutation electronic, Operation efficient, Permanent magnets, Position sensors, Electronic control, Reliable performance