On the design of A-C servo lead networks

PARALLEL-T AND bridged-T R-C (resistance-capacitance) networks are often used for the lead compensation of carrier-type servomechanisms. Presently available design methods require the use of cumbersome charts and do not readily permit evaluation of the relative gain. This paper carries out an analysis based on considerations of realizability. For each type of structure a realizability curve is determined. The analysis leads to equations relating the zero-frequency gain of the R-C networks to that of the R-L-C (where L is inductance) resonant damper. Finally, a very simple design method is derived, based on the conventional low-pass prototype, with no curves required.