Brushless DC torque motors quality level indexes for servo drive applications

The paper is devoted to motors static and dynamic qualitative characteristics required to compare and select brushless DC torque motors of different models and manufacturers for control systems and servo drives. By analyzing of 16 torque motors from 6 manufacturers it is shown that the most informative energetic index is the static torque quality factor measuring a developing torque per units of consumer power and the motor mass. Two dynamic indexes also discussed: mechanical and electrical time constants reflecting a torque motor structure. Selection of one of these indexes as the main factor depends of a drive application and design (gear or gearless).