EC Motors: Electronic Drives
Advancement in everyday technologies demand longer life motion systems with high efficiency like the innovation in 3D printing, small robotics, medical devices, and the small automation subsystems for industry and agriculture.
When considering an Electronic Commutated (EC) brushless motor system, the expectation is a controllable motion that performs over a many thousands of hours with high efficiency and predictable performance.
This motion technology starts with the Electronic Control Driver matched to an Electronically Commutated brushless motor platform. The relationship between the EC drive and the EC motor requires a balance of mechanical and electrical characteristics to efficiently perform in the application.
It is necessary to develop the EC driver to meet the input power demands of the EC motor that is configured to perform the efficient electrical energy conversion to the mechanical application work.For a balanced EC Drive system in an application these characteristics need to be considered:
- Power Required
- Mechanical Output Load Profile
- Mechanical Drive Load Characteristics
- Environmental Conditions
- Closed Loop or Open Loop Feedback Control
- Input / Output Interfaces Required
- Special Application Characteristics
Johnson Electric Matched EC Driver and EC Motor System
- EC Motor Mechanical Power Output for the Mechanical Drive Load Input
- EC Motor Geometric Configuration matched to the Mechanical Drive Inertia
- Match EC Motor Inductance to EC Drive Current Rise Time
- Open or Closed Feedback in the EC Driver and EC Motor
- Special Input / Output Interfacing on EC Driver for the Application Control
A Closed Loop feedback provides the EC Driver the magnetic rotor position and speed relative to the fixed EC Motor stator poles. A feedback signal can be generated by adding discrete Hall sensors positioned on the EC motor stator or in a sensorless system using the Back Electro Magnetic Force (BEMF) of the EC Motor. The generated BEMF is an analog signal induced in the EC Motor stator by the movement of the permanent magnet rotor. Both feedback systems use the zero voltage crossing point of the signals to do the computations required in synchronizing the drive powering the EC Motor stator in response to the rotor loads.
An open loop system provides no position feedback information to the controller; instead the controller uses a fixed preprogrammed drive signal that is modeled on a fixed application load using constants based on electrically and mechanically defined system parameters.
Johnson Electric’s EC driver and EC motor design teams can assist our customer in interfacing a balanced motion system to make a successful application.
EC Drive with Open Loop
EC Drive with Closed Loop Feedback