These small devices, located near the rotating magnets in the rotor, detect the rotor's position and send signals to the motor's control system. The MEAN WELL VFD module, distributed in Spain and Portugal by Electrónica OLFER, is designed to communicate with these Hall effect sensors to determine which stator coil should be energized next, ensuring smooth and efficient operation.
Furthermore, thanks to the VFD's exceptional compatibility and flexibility, it guarantees seamless integration for speed regulation, direction control, and start/stop operations. Examples of applications include conveyor belt motors in manufacturers requiring forward and reverse motion, precise speed control, and sudden braking when needed.
Figure 1. VFD module and BLDC motor with Hall sensor
A fan, for example, only needs simple, unidirectional motor operation upon startup. This application typically uses a sensorless BDLC motor to reduce system cost. These motors eliminate the need for Hall effect sensors and instead rely on natural electrical signals, the reverse electromotive force (EMF). When the rotor magnets rotate past the stator coils, they induce these reverse EMF signals. MEAN WELL's variable frequency drive (VFD) module is designed to "listen" to these reverse EMF signals (Figure 2).
By analyzing this feedback, the controller accurately determines the rotor position and adjusts the timing of the stator's magnetic field, ensuring smooth and efficient motor operation. This is similar to using sound echoes to map the dimensions of a room: precise and sensorless.
Figure 2. Sensorless motor starting voltage
As shown in Figure 2, during motor startup, there is a parking phase where the U, V, and W channels output a voltage to align the rotor. After this detection, the motor starts and the rotor begins to rotate.
In conclusion, the VFD series is a versatile and user-friendly solution for both sensor-based and sensorless BLDC motors. Its integration with an intuitive graphical user interface ensures accessibility for both novice and expert users. Whether simple setup or advanced customization is required, the VFD combines high performance with exceptional ease of use, meeting the demands of various industrial applications.
Author: Brian Lu, MEAN WEL Technical Service Center.
Translation: OLFER Electronics Marketing Department
