Control of Electric Motors

Reversible Drives using Choppers

Reversible Drives using Choppers: Using two quadrant choppers a reversible drive can be achieved, because this combination allows reversal of both current and voltage of the motor termi­nals. We can get a regenerative reversible drive. The motor can operate in all four quadrants. A scheme of a Reversible Drives using Choppers is shown in Fig. …

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Chopper Fed DC Drives

Chopper Fed DC Drives: The variable voltage to the armature of a dc motor for speed control can be obtained from a dc chopper which is a single stage dc to dc conversion device. The voltage variation at the load terminals can be obtained by using either current limit control or time ratio control. In …

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Methods to Leading Power Factor

Methods to Leading Power Factor: We have seen that a phase controlled converter requires reactive power for control and commutation. The harmonics do not contribute to the active power loading but they contribute to the reactive loading of the line. Because of these the line power factor is poor. A semi converter has been found …

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Three Phase Drives

Three Phase Drives: Single phase drives discussed in the previous section are employed for low and medium powers. When the power of the drive is very large the three-phase converter is preferred for supplying the load. As has been described early that increase in the number of pulses of the output voltage improves the performance. …

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