Four Quadrant Operation
Four Quadrant Operation
Four Quadrant Operation
From <https://www.tutorialspoint.com/four-quadrant-operation-of-dc-motor-motoring-and-breaking-
operation>
From <https://byjus.com/physics/difference-
between-ac-and-dc-motor/>
2 MARK QUESTION:_
Th e sinusoidal output waveshape is one of the most common requirements for the loads. This is usually accomplished by means of
driven inverter topologies. To obtain a sinusoidal output waveshape, the square, quasi, end or centre PWM waveform that is generated
from the inverter is passed through a filter such that the harmonics are attenuated and only the fundamental is allowed to pass
through to the load.
the filter should have a sharp cut-off profile to significantly attenuate the amplitudes of the third and higher harmonics.
In the sinusoidal pulse-width modulation technique, the pulse width of a high-frequency switching signal, called the carrier, is varied in
accordance to the amplitude of a low-frequency signal, called the modulating signal, as shown in Figure 6.42.
It is seen from the frequency spectrum that the major harmonic after the modulating signal frequency is at the carrier frequency. Th
erefore, to fi lter out the carrier from the PWM, the fi lter requirements are less stringent compared to fi ltering out the harmonics in a
square or a quasi-square waveform. As the fi lter is supposed to fi lter out only the high-frequency carrier, the fi lter size will be small.
Th e angular pulse width is proportional to the amplitude of the modulating signal value at the specifi c q values. Th e sinusoidal
modulating signal is compared with a high-frequency triangle or sawtooth wave form.
Th e points of intersection between the sinusoidal modulating signal and the triangle carrier are the angles at which the voltage
transitions take place. Every voltage transition is called a “notch”. Th e corres ponding angles at which these transitions occur are
called the “notch angles”.
Th e voltage transits between two levels from V+ to V– and vice-versa. V+ is usually the input DC voltage level Vdc and V– is usually –
Vdc or 0. At every notch, if the voltages transit between positive and negative voltage, then such a PWM is called bi-polar PWM as
depicted in Figure 6.43.
At every notch if the voltages transit between zero and either posi tive or negative voltage, then such a PWM is called a unipolar PWM
as illustrated in Figure 6.42
AS PER THE LENZ LAW THIS INDCED EMF OPPOSES ITS CAUSE, HERE CAUSE IS
RELATIVE SPEED BETWEEN STATOR AND ROTOR, AND THUS TO REDUCE THE
RELATIVE SPEED THE ROTOR ROTATES IN THE SAME DIRECTION OF STATOR.
ROTOR SPEED < STATOR SPEED, WHEN THE ROTOR SPEED = STATOR SPEED (I.E
DUE SUDDEN REMOVAL OF LOAD), THERE IS NO RELATIVE SPEED, HENCE NO
ROTOR EMF, NO ROTOR CURRENT THUS NO TORQUE HENCE SPEED REDUCES
AND BECOMES < STATOR SPEED.
OR