Sources of Error

One of the key observations when carrying out experimental work was the relative movement of the coils within their triplet groups. With a current flowing, the coils experience a force to follow the movement of the translator. With the rigid spacers only being present every third coil, there was some visible play in the coils, as they were compressed alternately against each spacer. In addition to this, a manufacturing defect allowed one end of the translator to enter the stator at the extremity of oscillation, Figure 5.38.

Figure 5.38: Translator entering stator

The effect of this manifests itself as the two outermost coils being briefly out of the influence of the permanent magnets, with a subsequent drop in induced emf.

Figure 5.39: Effect of translator error

Figure 5.39 shows the outer coils of the yellow and blue phases compared with their counterparts still above the translator. The induced emf is reduced by around 50%. This effect will partially account for the over prediction of the loaded model / underperformance of the machine.

5.7 Real Time Response

Figure 5.40: predicted internal emf and voltage drop at 1 m/s

Figure 5.40 shows the single phase voltage results obtained from running the simulation at a constant velocity whilst connected to an external load of 16 Ohms. Illustrated is the total voltage dropped across the internal and external resistors plotted on the same axes as the theoretical internal emf used in the model. Comparison of the two traces allows the power factor of the tubular machine to be calculated in two ways.

Firstly, the phase difference between the two signals can be measured, the cosine of which will give the power factor, detailed in section Secondly, relating the internal emf and voltage dropped across the machine's inductance to the power factor may be used. Both methods give a power factor of greater than 0.95.

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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