Name: current loops and torque in motors
Uploaded: 2023-04-30T12:41:03.000Z
Duration: 1 min 17 s
Channel: JoVE

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North Carolina K-12 Science Standard Course of Study

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Physical Science

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Motion and Stability- Forces and Interactions

PS.PSc.6.4

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Force On A Current Loop In A Magnetic Field

Электрическое устройство, преобразующее электрическую энергию в механическую, известно как двигатель постоянного тока. Он состоит из неподвижной части, статора, и вращающейся части, ротора.
В двигателях каждая петля провода находится в магнитном поле; когда ток протекает через петлю, силы, действующие на провод, ближайший к магнитным полюсам, направляются в противоположных направлениях, как это определено правилом правой руки. Магнитное поле прикладывает крутящий момент, который заставляет вал вращаться.
Рассмотрим прямоугольную токонесущую петлю из провода со сторонами длиной a и b в однородном магнитном поле.
Вспоминая уравнение магнитной силы на прямом токонесущем проводе, можно рассчитать магнитную силу на стороне 1 и стороне 3, а также определить направление с помощью правила правой руки.
Аналогично, ток на сторонах 2 и 4 перпендикулярен магнитному полю, и, таким образом, силы на этих сторонах могут быть определены.
Наконец, результирующую силу на петле можно рассчитать, сложив все силы с каждой стороны петли.

<ol>
	<li>OpenStax. (2019). Университетская физика Том 2. [Веб-версия], стр. 396 - 398. Получено из <a href="https://openstax.org/books/university-physics-volume-2@8ede2ba/pages/11-4-magnetic-force-on-a-current-carrying-conductor">https://openstax.org/books/university-physics-volume-2@8ede2ba/pages/11-4-magnetic-force-on-a-current-carrying-conductor</a></li>
</ol>

Сила на электрическую петлю в магнитном поле

Магнитные силы на проводах, по которым проходит электрический ток, наиболее часто применяются в моторах. Постоянный токовый двигатель - это устройство, которое преобразует электрическую энергию в механическую работу. В моторах проводные петли находятся в магнитном поле. Когда ток протекает через петли, магнитное поле создаёт крутящий момент, который вызывает вращение вала. Направление тока меняется, когда поверхность петли выравнивается вдоль магнитного поля, создавая постоянный момент на петле. Во время этого процесса используются коммутаторы и щётки для изменения направления тока. Коммутатор настроен на изменение направления потока тока в определённых точках, чтобы поддерживать непрерывное движение двигателя. Обычный коммутатор имеет три зоны контакта, чтобы избежать зон с нулевым моментом на петле. Щётки прижимаются к коммутатору, создавая электрический контакт между частями коммутатора во время вращения.

Рассмотрим прямоугольную проводницу с длинами сторон a и b, такую как петля в моторе, помещённую в однородное магнитное поле, как показано на рисунке 1.

<img alt="Equation1" src="/files/ftp_upload/13770/13770_PT_figure.svg" style="text-align: center; height: 250px;" />

Проводниковая петля испытывает силы, которые могут быть рассчитаны, применяя уравнение для магнитной силы на прямой провод, по которым протекает ток, к каждой стороне. Сила на сторону 1 и сторону 2 может быть рассчитана следующим образом:

<img alt="Equation1" src="/files/ftp_upload/13770/13770_Equation_1.svg" style="text-align: center; height: 18px;" />

<img alt="Equation2" src="/files/ftp_upload/13770/13770_Equation_2.svg" style="text-align: center; height: 18px;" />

Сила на сторону 3 и сторону 4 имеет такую же величину, но протекает в противоположном направлении по сравнению со стороной 1 и стороной 2 соответственно. Таким образом, сила на сторону 3 и сторону 4 равна силе на сторону 1 и сторону 2 соответственно, но с отрицательным знаком. Наконец, общая сила в проводящей петле равна сумме отдельных сил, действующих на каждую сторону петли, и может быть рассчитана следующим образом:

<img alt="Equation3" src="/files/ftp_upload/13770/13770_Equation_3.svg" style="text-align: center; height: 18px;" />

Магнитные силы на проводах, по которым проходит ток, чаще всего применяются в двигателях. Двигатель постоянного тока - это устройство, которое преобразует электрическую энергию в механическую ...

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Раздел 1

Magnetic Forces and Fields

Магнитные силы и поля

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

current loops and torque in motors

Current loops in a magnetic field create the torque that drives a DC motor. A DC motor converts electrical energy into mechanical work. In a motor, wire loops sit inside a magnetic field. When current flows through the loops, the magnetic field pushes on them and makes the shaft rotate.

The current is reversed when the loop lines up with the magnetic field. This keeps the torque on the loop going in the same direction. A commutator and brushes handle this reversal. The commutator switches the current flow at specific points, and the brushes keep electrical contact as the parts spin.

A basic commutator has three contact areas. This design helps avoid dead spots, which are points where the loop would have zero instantaneous torque. A rectangular loop of wire is a simple model for this process. If the loop has sides a and b and is placed in a uniform magnetic field, each side feels a magnetic force.

The force on each side can be found by applying the magnetic force equation for a straight current-carrying wire. The current on side 3 and side 4 has the same magnitude as on side 1 and side 2, but it flows in the opposite direction. That means the forces on side 3 and side 4 are equal to those on side 1 and side 2, but with a negative sign. The total force on the loop is the sum of the forces on all four sides.

Current Loops and Torque in Motors

magnetism

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force on a current loop in a magnetic field

Current loops in a magnetic field create the torque that drives a DC motor. A DC motor converts electrical energy into mechanical work. In a motor, wire loops sit inside a magnetic field. When current flows through the loops, the magnetic field pushes on them and makes the shaft rotate. The current is reversed when the loop lines up with the magnetic field. This keeps the torque on the loop going in the same direction. A commutator and brushes handle this reversal. The commutator switches the...

torque on a current loop in a magnetic field

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Learn how current loops in a magnetic field create torque in a DC motor, and how commutators and brushes keep the shaft turning.

Current Loops and Torque in Motors | JoVE K12

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Current Loops and Torque in Motors

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