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Brushless DC Electric Motors Within Medical Applications

Jul 13, 2017


Brushless DC Electric Motors Within Medical Applications

Sleep Apnea Treatment

The treatment of sleep apnea requires the use of Positive Airway Pressure (PAP) respirators. Most PAP respirators use a brushless DC motor to drive the blower fan. The blower fan creates positive airway pressure to aid the patient in breathing while they are asleep. In this application, the blower fan will increase or decrease the patient's airway pressure in response to their breathing pattern. When the patient inhales, the blower fan must increase the volume of air into the lungs, therefore the motor must accelerate. When the patient exhales, the blower fan must reduce the volume of air entering the lungs, therefore the motor must decelerate. Sensorless brushless DC drives are ideal for blower fans used in sleep apnea equipment because the motor is never required to operate below the minimum threshold speed of the drive. In addition, brushless types of DC electric motors are ideal for this type of application because there is no risk of a sudden change in load.Motors used in hospital equipment or other patient-care facilities are required to comply with low noise level standards to endorse patient comfort and reduce anxiety. Nevertheless, electric motors used in sleep apnea equipment operate at high speeds and are expected to comply with even lower noise level standards. Brushless DC motors are ideal for noise sensitive environments because they do not have brushes, which emit audible noise during rotation.

Medical Analyzer

Medical analyzers are multi-function machines used to test human bodily fluids such as blood and urine. In a medical analyzer, fluid samples are transported from station to station to conduct various tests. Generally, medical analyzers are totally enclosed and the temperature within the machine will rise to well above ambient temperature during periods of peak operation. Medical analyzers are designed to test thousands of samples per year and to run a minimal of eight hours per day. How can the brushless type of DC electric motors be used to optimize this process?Today, stepper motors, a close relative of DC electric motors, particularly the brushless kind, are the most common type of motor used in medical analyzers. Stepper motors are also considered to be "brushless DC" motors. However, the major difference is the construction and pole count of its rotor assembly. Stepper motors have a higher pole count than that of a brushless DC motor. The more poles a motor has, the lower its top speed. The need to develop machines with higher throughput requires the motor to rotate at speeds above the capability of stepper motors. Brushless DC motors are ideal for medical analyzers because they combine the characteristics of high speed operation, high heat transfer efficiency, and they have long life expectancies.

The BLDC motor will continue to emerge within medical applications. As sensorless brushless DC drives continue to develop and costs are reduced, the attractiveness of brushless DC motors will continue to increase. Customer demand for medical equipment capable of handling even higher throughput and of higher reliability than the machines of today will continue to challenge the capabilities of brushed DC electric motors. Lastly, the trend of reducing the size of medical equipment will require the motor's overall size to continue to become smaller.