A direct drive motor is a type of permanent-magnet synchronous motor which directly drives the load. In a DD motor, the use of a transmission or gearbox is eliminated—meaning that the number of moving parts in the system is reduced tremendously. The result is a very efficient electric motor and a quiet, highly dynamic operation. Consequently, the direct drive mechanism gives a motor a very high lifetime. Other examples of this technology are torque motors, linear motors and certain types of BLDC motors.
Geared motors have a lower torque to inertia ratio. This means that a lot of torque is required to accelerate the motor. In direct drive torque motors, the moment of inertia is low, which makes the motors very suitable for high-speed acceleration applications that need fast starts and stops.
Furthermore, a direct drive motor can also be supplied as a frameless motor, which is one without a frame, housing, bearing, or feedback system. The advantage of a frameless motor is that system suppliers can integrate it into an application easily; it eliminates the need for additional interfacing, and as such, reduces the cost of ownership.
Above all, a direct drive motor can be used for various applications, notably those where high positioning accuracy is needed. Frameless permanent magnet motors like these direct drive models are ideal for situations that demand small size, low weight, maximum power, and optimal speed control.
A direct drive motor provides:
- A cost-optimized solution, integrated and tailored to a specific application for best product performance.
- Increased efficiency: the power is not wasted in friction (from the belt, chain, or gearboxes, among other components).
- Reduced noise: being simpler, a direct-drive mechanism has fewer parts which could vibrate, and the overall noise emission is generally reduced.
- Longer lifetimes: fewer moving parts also means fewer parts prone to failure. Failures in other systems are usually caused by aging of the components (such as a stretched belt) or stress.
- High torque at low rpm.
- Faster and precise positioning: high torque and low inertia allow faster positioning times on permanent-magnet synchronous drives. Feedback also allows for precise angular position sensing.
- Reduced drive stiffness: mechanical backlash, hysteresis, and elasticity are removed when gearbox or ball screw mechanisms are not present.
These motors are in common use. Direct drive mechanisms are present in products such as fans, washing machines, sewing machines, wind turbines, and more.