01.11.2012 15:34

Brushless DC (BLDC) motors need to operate more efficiently as energy and cost savings become bigger concerns for designers of electronic devices. One way to help ensure greater efficiency is by selecting the correct bipolar latching Hall-effect sensor IC for electronic commutation in BLDC motors. These tiny ICs play a big role in motor efficiency, which can significantly affect the reliability and performance of many critical applications, including robotics, portable medical equipment and HVAC fans. These applications all call for a highly efficient and quiet motor.

Figure 1. Bipolar Hall-effect sensors are used in BLDC motors to detect the position of the rotating magnet. In this example, an eight-pole motor with a three-phase winding uses three bipolar latching Hall-effect sensors.BLDC motors use electronic instead of mechanical commutation to control the power distribution to the motor. Latching Hall-effect sensors, mounted in the motor, are used to measure the motor's position, which is communicated to the electronic controller to spin the motor at the right time and right orientation. These Hall-effect sensors are operated by a magnetic field from a permanent magnet or an electromagnet, responding to South (operate) and North (release) poles. These magnetic sensors determine when the current should be applied to the motor coils to make the magnets rotate at the right orientation.

There are several design characteristics that BLDC motor manufacturers should evaluate when selecting a bipolar latching Hall-effect sensor to commutate the motor so it can operate as efficiently as possible. These include sensitivity, repeatability, stability-over-temperature, and response time.

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