Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. If you continue browsing the site, you agree to the use of cookies on this website. See our User Agreement and Privacy Policy.

Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. If you continue browsing the site, you agree to the use of cookies on this website. See our Privacy Policy and User Agreement for details.

Like this presentation? Why not share!

- DC Motor Control By Using A Chopper... by Birol Arslan 16657 views
- Choppers by Aniruddha Gautam 14525 views
- Dc chhopers by Esys India Malegaon 7015 views
- Report on speed control of d.c. mot... by SHIVAM SINGH 33217 views
- Dc Choppers by stooty s 41759 views
- TO control the speed of DC Motor Si... by ZunAib Ali 27332 views

No Downloads

Total views

5,825

On SlideShare

0

From Embeds

0

Number of Embeds

3

Shares

0

Downloads

321

Comments

0

Likes

6

No embeds

No notes for slide

the motor.

[3rd point] The problem of power factor does not occur at all. The conventional phase control method

suffers from a poor power factor as the angle is delayed.

- 1. MULTIQUADRANT CONTROL OF CHOPPER-FED DC MOTORS Institute of Industrial Electronics Engineering-Karachi Presentation by Muhammad Ahsan Ali (1915)
- 2. CHOPPER • Chopper is a static device. • A variable dc voltage is obtained from a constant dc voltage source. • Also known as dc-to-dc converter. • Widely used for motor control. • Also used in regenerative braking. • Thyristor converter offers greater efficiency, faster response, lower maintenance, smaller size and smooth control.
- 3. CHOPPER FED DC DRIVES • A dc chopper is connected between a fixed-voltage dc source and dc motor to vary the armature voltage. • A chopper is a high speed on/off semiconductor switch which connects source to load and disconnects the load from source at a fast speed. • Choppers are used to get variable dc voltage from a dc source of fixed voltage. • Chopper circuits are used to control both separately excited and Series circuits.
- 4. ADVANTAGES OF CHOPPER CIRCUITS • Ripple content in the output is small. • Peak/average and rms/average current ratios are small. • The chopper is supplied from a constant dc voltage using batteries. • Current drawn by the chopper is smaller than in phase controlled converters. • Chopper circuit is simple and can be modified to provide regeneration and the control is also simple.
- 5. CONTROL MODES OF DC CHOPPER DRIVE 1. Power(or acceleration) control 2. Regenerative brake control 3. Rheostatic brake control 4. Combined Regenerative and Rheostatic Brake Control
- 6. POWER CONTROL
- 7. WAVEFORM SUMMARY (Highly Inductive Load) Ripple-free Armature Current sa kVV asaao IkVIVP a s s s eq kI V I V R m m m s fL R R V I 4 tanhmax Armature Voltage: Power suplpied: Input Resistance: Peak-to-peak current: where k =conduction duty cycle
- 8. REGENERATIVE BRAKE CONTROL
- 9. WAVEFORM SUMMARY
- 10. EQUATIONS sch VkV )1( )1( kVIP sag amsg IRVkE )(1 m a s a g eq Rk I V I E R )1( max max min min fv am fv s fv am IK IR IK V IK IR Voltage across transistor: Regenerated power: Voltage when motor acting as generator: Equivalent load resistance: Minimum Braking Speed: Maximum Braking Speed:
- 11. RHEOSTATIC BRAKE CONTROL
- 12. WAVEFORM SUMMARY
- 13. EQUATIONS • The average current in the braking resistor is • The average voltage across the braking resistor is )1( kII ab )1( kIRV abb • The equivalent load resistance of the generator • The power dissipated in the resistor Rb is mb a b eq RkR I V R )1( )1(2 kRIP bab
- 14. COMBINED REGENERATIVE AND RHEOSTATIC BRAKE CONTROL
- 15. • Used when the supply is partly “receptive” • Remove regenerative braking if line voltage is too high – Turn thyristor TR on – Divert current to RB – Apply rheostatic braking – TR is “self-commutated” COMBINED REGENERATIVE AND RHEOSTATIC BRAKE CONTROL (CONT.)
- 16. MULTIQUADRANT CHOPPER DRIVES o Forward Power Control (I-Quadrant) o Forward Regeneration (II-Quadrant) o Reverse Power Control (III-Quadrant) o Reverse Regeneration (IV-Quadrant) • Control Modes
- 17. Forward Power Control Q1 T1 & T4 is ON Current Flow : VS + _ T1 _Motor_T4_VS - Current Ia & Va are positive Operates in First Quadrant
- 18. T1 is OFF & T4 is ON. Inductor current has to flow in the same Direction. Diode D1 is FB Inductor Current freewheels through D1 & T4 Output Voltage is Zero Forward Power Control (cont.)
- 19. T4 is OFF. T2 is ON. (Load is not connected with the source). Back Emf drives the current through T2 & D3 Forward Power Control (cont.)
- 20. Q2 T2 is OFF. Diode D2 is FB Current flows through D3 & D1 Current Ia is negative & Va is positive. Operates in second quadrant. FORWARD REGENERATION
- 21. Q3 T3 & T2 is ON Current Flow : Vdc + _ T3 _Motor_T2_Vdc - Current Ia & Va are negative Operates in third Quadrant Reverse Power Control
- 22. Q4 T4 IS Turned Off, D4 is FB Current Flows through Va+ - D1 – D4 – Va- Va is negative. But current Ia is positive Operates in fourth quadrant REVERSE REGENERATION
- 23. References • Power Electronics: Circuit Devices and Application By Haroon Rashid • Digital Power Electronics and Applications By Ling Luo, M. Rashid
- 24. THANK YOU

No public clipboards found for this slide

×
### Save the most important slides with Clipping

Clipping is a handy way to collect and organize the most important slides from a presentation. You can keep your great finds in clipboards organized around topics.

Be the first to comment