Final answer:
The MMF waveform of each phase in a 3-phase AC machine is a sinusoidal wave based on the current, coil turns, and winding distribution. The resultant MMF waveform is obtained by adding the individual phase MMFs, taking into account their 120-degree phase displacement in the abc sequence.
Step-by-step explanation:
MMF Waveform for a 3-phase AC Machine
The subject in question involves the magnetomotive force (MMF) waveform produced by a 3-phase, 4-pole alternating current (AC) machine with specific parameters. To draw the MMF waveform for each phase and the resultant MMF, one must understand how these waves are derived from the electrical inputs and slot distribution.
For each phase, the MMF wave will look like a sinusoidal waveform. The amplitude of the MMF waveform for a given phase is proportional to the number of turns, current, and the winding factor associated with the coil distribution in the slots. In this case, the currents in the three phases are given as: Ia=10 A, Ib=-5 A, and Ic=-5 A. The phase displacement is 120 degrees in the abc sequence, which will affect the phase relationship of the individual MMF waveforms.
For the resultant MMF due to all phases, the MMF waves of each phase are added vectorially. This means that the resultant MMF waveform is found by superposing the three MMF waveforms, considering their phase differences due to the abc sequence. The resultant waveform is more complex than a single sinusoid, reflecting the composite effect of the currents in all three coils.
Creating an exact graphical representation of the MMF waves requires plotting the superposition of sinusoidal waves, which is often done using simulation software or a detailed hand-drawing based on calculations that take into account the phases' relative angular displacements. However, the key idea is that the MMF of each phase is a sinusoid, and the overall MMF is the sum of these three waves shifted by their respective phase angles.