It depends on specific application situation, and to put it in a simple way: Nature of load (for example, vertical load or horizontal load), requirements of torque, inertia, speed, accuracy and acceleration and deceleration, requirements of upper control (such as requirements of port interface and communication), whether major controlling mode is position, torque or speed mode, whether power supply is direct or alternating current power supply, or battery powered, and voltage scope. Based on this, we can determine models of motor and supporting drives or controllers.