It is well known that a 2-phase servomotor is used in automatic balancing type recorders, servooperators and the final control elements of various servomechanisms, etc.
However, we have little information on the generating torque of a 2-phase servomotor operating with a 2-phase source which contains higher harmonic components in the control windings current.
This paper presents the following:
(1) The generating torque of a 2-phase servomotor in the above operating condition is analysed using the elementary method. In this analysis, the general torque equation containing both the average torque and the alternating torque is derived, and the kinds of generating torque are clarified.
Moreover, a table of these generating torques, which consists of the stator's field and the rotor's current is constructed, and the causes of generating various torques are pointed out.
(2) In comparing and investigating the results obtained by means of both the elementary method and the 2-phase symmetrical component method, the generating torque equations are expressed by using the equivalent circuit parameters of the 2-phase servomotor.
(3) In order to check the appropriateness of the above equations, the calculated results are compared with those of the experiment. The comparison between the calculated results and the experimental ones is satisfactory.
(4) The digital simulation of the exact equations derived as in (2) above, reveals which higher harmonic components to neglect and which torque components to label as significant. Consequently, more simplified versions of the exact equations can be derived.
(5) By the simplified equations the alternating torque characteristics of the 2-phase servomotor under various conditions are investigated, and the influence of an alternating torque on the average torque is analysed. In this investigation the alternating torque characteristics of the 2-phase servomotor are explained.
