Brushless Mortor｜Basic

Features and Applications of 3-Phase Full-Wave Brushless Motors ーSummaryー

2023.08.30

Points of this article

・The most important advantages are, because of the absence of a brush, reduced electrical and mechanical noise, high reliability, and a long lifetime.

・Disadvantages are the cost increases due to the complicated electronic circuitry and sensors that are needed for the rectification function.

The past ten articles have discussed the features and applications of 3-phase full-wave brushless motors. Here a summary is provided.

Features of 3-Phase Full-Wave Brushless Motors

Features, advantages, and disadvantages of 3-phase full-wave brushless motors are summarized below. Items in bold are particularly important.

Advantages	Disadvantages
・Minimal electrical, mechanical noise ・High reliability, long lifetime ・Easily reaches high speeds ・High efficiency ・Easily miniaturized and designed in various shapes ・Rotation speed proportional to applied voltage ・Rotation speed falls in proportion to load ・Large torque on startup and at low speeds ・Torque proportional to current ・Main characteristics vary linearly, making control easy	・Rotor is a permanent magnet, so moment of inertia cannot be decreased ・Added costs due to complicated electronic circuits and sensors required for rectification function ・Numerous wires needed between driving circuit and motor ・Tendency for torque fluctuation (when coils have iron cores)

Advantages

Disadvantages

・Minimal electrical, mechanical noise
・High reliability, long lifetime
・Easily reaches high speeds
・High efficiency
・Easily miniaturized and designed in various shapes
・Rotation speed proportional to applied voltage
・Rotation speed falls in proportion to load
・Large torque on startup and at low speeds
・Torque proportional to current
・Main characteristics vary linearly, making control easy

・Rotor is a permanent magnet, so moment of inertia cannot be decreased
・Added costs due to complicated electronic circuits and sensors required for rectification function
・Numerous wires needed between driving circuit and motor
・Tendency for torque fluctuation (when coils have iron cores)

Application Examples of 3-Phase Full-Wave Brushless Motors

Examples of the use of 3-phase full-wave brushless motors in representative equipment and devices are summarized. There are many and varied other applications as well; these should be understood as limited examples.

Equipment	Application examples
HDD	・Spindles: Disc rotation → 3-phase sensorless
PCs/Game console DVD drives/Blu-ray drives Blu-ray recorders/players	・Spindles: Disc rotation → 3-phase sensorless
Laser-beam printers (LBP) PPC	・Paper feed　→ 3-phase sensored ・Polygon mirrors: Rotation of polygon mirrors for laser light scanning　→3-phase sensored, 3-phase sensorless
DC fan	→2-phase half-wave brushless, Single-phase full-wave brushless, 3-phase sensorless
Drones	・Propellors　→ 3-phase sensorless ・Gimbal control: Fixing camera directions　→ 3-phase sensorless
Machine tools	・Screwdrivers, ・Drills, ・Saws, etc.: Rotation　→ 3-phase sensored
Home appliances	・Air conditioners: Compressors, fans (indoor, outdoor), ・Air purifiers ・Vacuum cleaners etc., Refrigerators (Compressors, fans)
Automotive	・Air conditioners: Fans，・Battery cooling fans ・Seats: Fans etc., Pumps

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