Excitation voltage

Fig. 4.14 DC servo-motor under armature control, e it) = Armature excitation voltage e it) = Backemf /a(t) = Armature current = Armature resistance = Armature inductance 6f = Constant field voltage if = Constant field current Tm = Torgue developed by motor 6 t) = Shaft angular displacement u] t) = Shaft angular velocity = dd/dt.

Straight Shunt-Wound Motor. A straight shunt-wound motor is a direct-current motor in which.the field circuit is connected either in parallel with the armature circuit or to a separate source of excitation voltage. The shunt field is the only winding supplying f ield excitation. 

Another technique that is useful at frequencies of less than —10 kHz is phase-selective demodulation. A distinct advantage of this technique is that it enables the separation of the resistive (in-phase or real ) and capacitive (90°-out-of-phase or quadrature ) components of the cell impedance. This is accomplished through the process of cross-correlation [13] (selecting that component of es that correlates with the phase of i). The excitation voltage waveform is multiplied by a square wave that is in phase with the cell current waveform. 

The ferroelectric sample is pre-polarized by measuring a complete hysteresis. The excitation voltage is then kept constant for the relaxation time at a particular voltage. The relaxed... 

Steep gradients could not be achieved in these macroscopic devices and high excitation voltages were needed to compensate for this. The situation changed with the advent of 3-dimensional micro-electrodes fabricated on glass and... 

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