Challenge

Week-7 Challenge: DC Motor Control

Question 1a):

Question 1b):

The armature current (Ia) is on during the 1^st transition and off during the 2^nd transition
It is controlled by the IGBT, BJT, diode in the circuit of the motors given
In the 1^st transition phase q1 and q4 are active
And in 2^nd transition phase q3 and q4 are active
It clearly shows that the armature current varies on the transition state caused by the motor
When in conducting state the BJT operates in the saturated region where the forward voltage is developed between emitter and the collector
IGBT does not simulate the gate current controlling the BJT and it is controlled by Simulink
The transistors are switched simultaneously

Question 1c):

The four quadrant DC7 chopper is explained in the above model
222 HP dc motor is excited with a constant 50V dc voltage source
Armature voltage is given by IGBT converter controlled by two PI regulators
Converter is fed by 515V dc bus by the rectification of 380V ac 50 Hz voltage source
To limit the dc bus voltage during dynamic braking mode or braking chopper is added in the rectifier
Speed regulator outputs the armature current
The current controller in order to obtain electromagnetic torque to reach the desired speed
Acceleration and deceleration are used to avoid the over armature current
The IGBT 2 and 3 are opposite to 1 and 4
Four quadrant chopper has higher switching frequency than h bridge
Armature current variation is high in four quadrant than in h bridge
H bridge are small electronics application and chopper is used for industry

Question 3:

Explanation:

BLDC – brushless dc motor
It uses permanent magnet synchronous electric motor driven by dc current
The commutation is controlled by electric commutation method
It does not have brushes it has a mechanical contact with the commutator
Electric path between source and rotor employs electric commutation by permanent magnet rotor and a stator coil
The magnet with the poles rotates and the conductors which carries current are fixed
Coils are switched electronically by the SCR
Electronic commutation wipe out the commutator arrangement and brushes in dc motor
Conventional method is a brushed dc motor
The brushed dc motor have wear and tear in the circuit
Heat is low when compared to brushed dc motor
Efficiency of BLDC is high
It do not undergo wear and tear of brushes because there is no brushes in it
Noise is less as of brushed dc motor
Motor cost is too high
Permanent magnet in the motors can be demagnetized by mmf and high temperature

Refernce:https://www.renesas.com/us/en/support/engineer-school/brushless-dc-motor-01-overview

Conclusion:

All the theory with demo model is explained.

Ship work like this
in your own course.