analysis and improvement of two-motor selsyn

in most industrial applications, including overhead cranes, two motors with equal speeds are required. to meet this, different traditional and modern methods are used. in the modern methods, work is done with more precision but the cost is remarkably high, also the maintenance of equipment needs specialized personnel. among traditional methods, the two-motors selsyn method is noteworthy due to its considerable low cost. but this method has some problems in starting with high rotor resistance, working at nominal speed, and braking. in this paper after analyzing of selsyn methods, the stability conditions and some problems that occur in two-motor selsyn have been studied. in continuation, some solutions have been suggested and the effectiveness of the system has been validated through practical tests and simulation results.