What Is a Direct Drive Motor?
Many motor and controller companies use the term Direct Drive quite liberally (and at times incorrectly) to describe their systems to potential OEMs and system integrators. Direct Drive motors are simply motors that power a system (e.g. pump, fan blades, conveyor belt, door opener, etc.) directly without requiring a gearbox to achieve the necessary torque. Many systems have traditionally used induction motors with gearboxes, mainly to achieve their cost targets, but a new proprietary brushless DC motor design introduced by ETM in 2013 generates the necessary continuous torque without the gearbox.
The advantages of using true Direct Drive motors are many, including smaller size, less noise, higher reliability, larger speed range (less inventory), higher efficiency, and in most cases lower costs. The concept is simple – if you can remove the large, noisy, inefficient, and least reliable part of the system (gearbox) and meet the torque with the motor alone, your system will be better in every aspect.
How does it compare to what I’m already using?
There are a number of the technical innovations in ETM direct drive motors, from pole design to copper winding design, that provides significant torque, size and cost advantages. ETM motors have proven to be a direct replacement for AC-induction and BLDC motors currently used in high duty cycle, low speed applications. The motors have up to 4x more torque than conventional BLDC motors and up to 10x more torque than AC-Induction Motors (comparison table below). This enables designers to not only eliminate the gearbox, but also significantly decrease the size and, therefore, cost of the motors. It’s a simpler, more reliable, efficient motor design that can reduce energy losses by 60 – 80%!
BLDC Motor/Gearbox vs ETM Direct Drive
Where should I consider using ETM Direct Drive Motors?
Direct drive motors really shine in high continuous torque, relatively low speed (less than 1500 rpm) applications. ETM motors can also achieve high power at low rotational speeds… even at stall! This enables very high turndown ratios (think 1,000:1) without a gearbox. Ideal applications for direct drive motors include HVLS & Axial Fan Motors, Industrial Door Motors, Positive Displacement Pump Motors, Conveyor Motors, and others.
1/2 HP 10:1 Motor Comparison
AC 1/2 HP 10:1
BLDC Direct Drive
ETM Direct Drive
| AC 1/2 HP 10:1 | BLDC Direct Drive | ETM Direct Drive | |
|---|---|---|---|
| Full Load Torque, ft-lb | 15.1 | 15.0 | 15.4 |
| Full Load RPM | 175 | 200 | 200 |
| Weight, lbs | 50 | 59 | 18.7 |
| Volume, cuin | 506 | 462 | 81 |