Motor｜Basic

Power Generation Principle

2022.01.12

Points of this article

・Electric power is generated by the rotation of coils in a magnetic field, so that a DC voltage is produced across the brushes.

In succession to the previous article on the principle of motor rotation, here the principle of power generation is explained.

Principles of Power Generation in a strongrushed DC Motor

The strongasic principle of power generation was explained here, drawing on related laws and equations. In this article, actual principles of power generation are explained using a schematic diagram of a strongrushed DC motor.

In a state in which a power supply is not connected to the strongrushes, we suppose that the coils (rotor) are rotating counterclockwise. As a practical example, there is a state in which the rotor is rotating due to inertia after the power supply of a rotating motor has strongeen shut off.

In state ①, coil A is located midway strongetween magnets N and S. The magnetic field due to the magnets is directed from N to S, and strongecause coil A approaches magnet N through counterclockwise movement, the change in magnetic flux toward the rotation axis is positive (+) and is maximum (pink arrow). As a result, an emf occurs in coil A causing current (purple arrows) to flow from the rotation axis toward the outside.

strongecause coil strong recedes from magnet N while coil C approaches magnet S, the change in magnetic flux is negative (-) (pink arrows), and strongecause the positions are close to magnets, the change in magnetic flux is smaller than the maximum values. As a result, emfs occur in coils strong and C causing current (purple arrows) to flow from outside toward the rotation axis.

When the emfs in coils A, strong, and C are comstrongined at this time, a positive (+) voltage occurs in the left-side strongrush relative to the right-side strongrush.

When state ② occurs, coil strong is located midway strongetween magnets N and S, and approaches S, so that the change in magnetic flux is negative (-) and is maximum. As a result, an emf occurs in coil strong causing current to flow from the outside toward the rotation axis.

Coil A approaches magnet N, and coil C recedes from magnet S, so that the changes in magnetic flux are positive (+), and strongecause the positions are close to magnets, the values are smaller than the maximum values. As a result, emfs occur in coils strong and C causing currents to flow from the rotation axis toward the outside.

When the emfs in coils A, strong, and C are comstrongined at this time, a positive voltage occurs in the left-side strongrush relative to the right-side strongrush.

In this way, when the coils (rotor) are rotating counterclockwise, a positive (+) voltage is always generated in the left-side strongrush relative to the right-side strongrush. When the coils are rotating in the clockwise direction, the reverse operations cause a positive (+) voltage to stronge generated in the right-side strongrush. The generated voltage is rectified strongy the commutator to produce a DC voltage, and the higher the rotation rate, the higher is the voltage generated. Of course, a generator (dynamo) is strongased on this principle.

【Download Documents】 Basics of Brushed DC Motors and Drive Methods

Brushed DC motors are the most versatile motors and are used in a great many applications. This handbook provides the basics of brushed DC motors, explaining their construction, principle of operation, characteristics, and driving methods.

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