Brushless DC Motors

Brushless DC motor from PC floppy disk drive

Brushless DC motors (BLDC motors) have no the wear and tear on the commutator as in conventional DC motors. In brushless DC motors the permanent magnet is located in the rotor and the coils are located in the stator. The coil windings create a rotating magnetic field because they are separate from each other electrically, which allows them to be turned on and off. The commutator in this motor does not carry the current to the rotor. Instead, the rotor's permanent magnet field chases the rotating stator field, making the rotor turn. One other key component of the brushless DC motor is the use of electronic circuitry and sensors with the commutator to excite the motor to produce torque.

BLDC motors are widely used in many devices such as computer hard drives and CD/DVD players. Small cooling fans in electronic equipment are powered exclusively by BLDC motors. They are used in battery power tools where the increased efficiency of the motor leads to longer periods of use before the battery needs to be charged. Low speed, low power BLDC motors are used in direct-drive for "analog" audio discs.

Exercise 1. Translate from Russian into English.

1.Двигатель постоянного тока преобразует электрическую энергию в механическую энергию, и является простейшим видом мотора.

2. Ток, проходящий через якорь двигателя постоянного тока, дает магнитное поле, которое взаимодействует с магнитными полями полюсов статора и вращает якорь.

3. Коллектор соединяет источник питания с якорем с помощью щеток.

4. Полевые катушки и якорь в двигателе с параллельным возбуждением соединены параллельно.

5. В двигателе с сериесным возбуждением, полевые катушки и якорь соединены последовательно.

6. В бесщеточном двигателе постоянный магнит расположен в роторе, а катушки расположены в статоре.

7. В бесщеточном двигателе поле постоянного магнита ротора догоняет вращающееся магнитное поле статора, создавая вращение ротора.

Read the English words and their translation into Russian. Then cover the left column and translate the Russian words back into English.

induction motor асинхронный электродвигатель

synchronous motor синхронный электродвигатель

electromagnetic induction электромагнитная индукция

induced индуцированный, наведённый

induced emf наведённая электродвижущая сила, наведённая эдс

closed loop короткозамкнутый виток

to exert [Ig'zWt] приводить в действие

life time срок службы, долговечность

industrial machinery промышленное оборудование

Text 2

AC motors

AC motors are electromagnetic devices that have an alternating current as a power source. Their function is to convert mechanical energy into electrical energy that can perform work. They operate on the principle of Faraday law of induction, which states that a rapidly changing magnetic field produces an induced emf or voltage.

Wires that carry current produce magnetic fields. Michael Faraday discovered that when a wire is in a changing magnetic field, a current is induced just as if there were a source of emf. The more rapid the changing field, the greater the generated emf.

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