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 termi¬≠nals. 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. […]

Reversible Drive using Field Reversal

Reversible Drive using Field Reversal: A Reversible Drive using Field Reversal can be realised as shown in Figs. 4.83 and 4.84. In Fig. 4.83, the armature is fed from a two quadrant converter with change over mechanical contactors in the field, which is also fed from a two quadrant converter. In the process of reversal […]

Reversible Drive using Dual Converter

Reversible Drive using Dual Converter: It is possible to reverse both voltage and current of the load using a dual converter. The current reversal is very fast in this case as the system is static without the mechanical output. A Reversible Drive using Dual Converter can be operated in either circulating current mode or circulating […]

Reversible Drive using Armature Current Reversal

Reversible Drive using Armature Current Reversal: A schematic of a reversible drive using contactors to reverse the Armature Current Reversal for reversing the rotation is shown kin Fig. 4.81. The contactors F1¬†and F2 are provided for rotation in the forward direction, whereas R1 and R2 in the reverse direction. This arrangement reverses the current in […]

Reversible Drives using Phase Controlled Converters

Reversible Drives: When speed control in both forward and reverse directions is required a Reversible Drives is used. In several applications the speed reversal may be required very frequently in which case a regenerative reversal may be advantageous. The drive is very efficient as the kinetic energy of rotating parts is returned to the supply. […]

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 […]

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 […]

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. […]

Single Phase DC Series Motor Drives

Single Phase DC Series Motor Drives: In the Single Phase DC Series Motor Drives the field is connected in series with the armature. The field current is the same as the armature current. The schematic of a Single Phase DC Series Motor Drives fed from a phase controlled converter is shown in Fig. 4.62. DC […]

Single Phase Separately Excited DC Motor Drives

Single Phase Separately Excited DC Motor Drives: The circuit arrangement of a Single Phase Separately Excited DC Motor Drives Drives fed from a single phase controlled converter is shown in Fig. 4.56. The block 1 can be any one of the single phase converters. Half wave drives: The Single Phase Separately Excited DC Motor Drives […]

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