Abstract
The proportional voltage method is to-day prevailingly used to measure the individual synchro error. The error measured by this method is called the electrical error. The synchro electrical error has two principal frequency components. One is the space harmonic component of the magnetic flux distribution such as the 6th harmonics or the 12th. The other is the 2nd component due to the unbalance of induced secondary voltages in the 3 phase windings.
The relation between the unbalance factors K, δ and the maximum value of electrical error can be derived from the equations of the proportional voltage method. The mutual relations between the unbalance factors based on the different reference phases are also calculated in this paper.
There is no precise rule to select the reference phase from among the terminals S1, S2, S3 of the synchro stator windings. It is proposed that the preferable domain is the 120° sector, the center line of which is the K-axis in K>1 on the Kδ diagram. A positive maximum value shall lie in the interval between 15° and 75° of the synchro error curves. Thus the suitable use of the 2nd harmonic characteristics of the synchro error results in minimizing the synchro system error.
