Equalization of Torques in Multi Motor Electric Drives with Estimation of Motors Parameters

Multi-motor electric drives are the systems in which torques's of two or more electric motors are summarized. This summing up may be performed directly on the common shaft or indirectly, for example, on common load. In any case there is a problem of common torque distribution among the motors for most effective use of them without overload. The common solution of the problem is to achieve equal torque distribution among the motors. There are some ways to achieve the equality of motor torques in multi motor drive. One of them is matching mechanical characteristics of the motors by correcting independently the no-load speed and the hardness of all the motors of the drive. This way allows keeping desired torque distribution at variable drive load, but it requires using of two independent correction signals for no-load speed and hardness of each the motor, that calls for need the mathematical tool to determinate the reasons of non-equal common torque distribution. The aim of the paper - determinate the reasons of non-equal torque distribution in multi-motor drive by analyzing the functional dependencies between the motor torques non-equalities and the total drive torque.