Four Tips For Choosing A DC Or BLDC Motor

Anyone who relies on compact DC motors in drive technology must first make a choice: between brushed (DC) and brushless (BLDC) motors. The text below is meant to be a guide to choosing the right motor type for a particular application.

Lifespan difficult to predict

The commutation system with brushes limits the lifespan of the DC motor. Usually you can reach a few thousand hours, in the best case maybe 10,000 hours. However, the service life can be over after less than 100 hours. An exact prediction is hardly possible because there are no reliable calculations. A lot depends on the load: high current, high speed, reverse operation and high vibrations reduce the service life. A comparison with a similar application is therefore often required. In brushless DC motors, the ball bearings limit the life of the motor, which can be estimated fairly precisely. The bearings are typically designed for several 10,000 hours.

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TIP: The following still applies: For many applications, an operating time of a few 1000 hours is sufficient.

Check speed and torque

As a starting point, we consider a brushed DC motor of a given size. So you can speed up to 20,000 min ^-1 reach. In most cases, the limit speed is below 10,000 min ^-1. At higher speeds, the service life of the engine decreases massively due to increasing electrical and mechanical wear. A brushless DC motor of comparable size and magnetic construction can be operated at much higher speeds, in individual cases over 100,000 min ^-1. Such drives are therefore perfectly suitable in applications that require a lot of speed: for example for industrial cutters, milling cutters and certain fans.

It is interesting that brushless motors are often designed with multiple poles. This increases the torque, but at the expense of the speed. Because many applications do not need the extremely high speeds; a little more torque is very welcome. And yet, one of the main advantages of brushless motors is the higher speeds that these motors achieve.

TIP: Note: These versions are only trends. Which speeds and torques are possible must be clarified specifically for the respective engine type.

Content of the article:

• Page 1: Four tips for choosing a DC or BLDC motor
• Page 2: Observe environmental conditions

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