At present, the most obvious trend in motor drive and control is to adopt brushless direct current (BLDC) motors, but when considering the conversion of a design to BLDC, you must carefully consider the reasons for doing so. According to Dan Jacques, Strategic Marketing Manager at Allegro MicroSystems, LLC, the cost of BLDC motors and drive systems has been significantly reduced through upgrades and integration. For BLDC motor drivers with or without sensors, the main considerations are reliability, audible noise and overall efficiency.

    Allegro MicroSystems, LLC

    Mr. Dan Jacques, Strategic Marketing Manager
    Due to the optimized structure design of BLDC motor, its reliability is higher. Mr. Dan Jacques emphasized that when considering senserless BLDC motor drives, reliability at the start is crucial, and good control and measurement of the start parameters ensures reliability at the senserless start. Allegro motor driver ics are highly programmable and can drive a very wide range of motors. If the primary goal of the design is to reduce the cost of the system, it is generally necessary to achieve this through a sensorless system, which can save the cost of Hall sensors, wires and connectors. In addition, motors such as integrated closed-loop speed control can reduce or even eliminate the need for a system microprocessor, which can further reduce system costs.
    Improvements in BLDC motor efficiency can also be achieved by reducing the vibration of the motor and providing the appropriate phase advance for the motor speed. The Allegro motor driver algorithm reduces noise and vibration by driving the motor windings with a sine wave drive current, thereby improving efficiency. Allegro's patented automatic lead angle adjustment technology ensures that motor drive efficiency is automatically optimised at any motor speed.
    Allegro has been continuously expanding its BLDC portfolio in the commercial, industrial and automotive markets. The A5931 is an EEPROM programmable sensorless BLDC motor driver with sine wave modulation to achieve the lowest audible noise, and the integrated three-phase bridge enables the driver to have a low RDSon of 100mΩ. The A5931 also includes integrated closed-loop speed control, overcurrent protection, and Allegro's proprietary phase advance algorithm. Allegro's solution not only provides hardware for BLDC motor drives, but also an easy-to-use GUI that allows engineers to change parameters in real time while reading diagnostics, which eliminates the need for engineers to master microcontroller programming and the development of sine wave control algorithms.