Single-phase direct-current brushless position-sensorless motor and fan comprising the same

Abstract

The invention discloses a single-phase direct-current brushless position-sensorless motor and a fan formed by the single-phase direct-current brushless position-sensorless motor. The motor provided bythe invention adopts a single-phase direct-current brushless variable air gap structure, and the gap distance of an air gap is reduced from an inlet end to an ending end; the air gap structure enables the air gap magnetic flux to change in a function relationship along with the change of the relative positions of the rotor magnetic poles and the stator teeth. A current value in a current coil isobtained through a current sampling resistor R6 single-chip microcomputer, the current, the position of a brushless motor rotor and the rotating speed are in a function relationship, and the current rotor position can be calculated through the current. The motor adopts a position-sensorless mode, the work of a driving circuit is not influenced by motor vibration and temperature rise, and the reliability of the motor is improved.

Description

technical field [0001] The invention relates to the field of motors, in particular to a single-phase DC brushless motor without a position sensor and a fan formed therefrom. Background technique [0002] Single-phase DC brushless motor is driven by only a single phase current in the excitation coil, and the rotor part is composed of permanent magnets or excitation coils with paired magnetic poles. The motor back EMF is a single phase AC voltage. The drive current commutation is completed by an external circuit, and the commutation time point is provided by an external Hall position sensor. [0003] The current single-phase DC brushless motors have the following problems: [0004] 1) The current motor uses a Hall sensor switch to generate a signal at the moment when the rotor magnetic pole is switched, so as to know the current position of the rotor. The conventional Hall sensor switch can only generate a signal at the moment when the rotor magnetic pole is switched. During...

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Problems solved by technology

[0004] 1) The current motor uses a Hall sensor switch to generate a signal at the moment when the rotor magnetic pole is switched, so as to know the current position of the rotor. The conventional Hall sensor switch can only generate a signal at the moment when the rotor magnetic pole is switched. During the rotor transfer process The current position of the rotor cannot be known, so it can only be driven by a square wave, the driving efficiency is low, the torque fluctuation is large, and the electromagnetic noise is large during operation;

[0005] 2) Due to the use of Hall sensors for position sensing, the drive circuit that provides the drive current is powered by a single-cell lithium battery and needs a booster circuit to reduce the drive current, resulting in a complex drive circuit and many power devices in series in the coil drive current path. Low circuit efficiency, high cost, and reduced reliability;

[0006] 3) At present, the motor part and the drive chip in the single-phase DC brushless motor are installed together. When the motor part is in the working state, the motor core and coil will generate heat during work, which makes the working environment of the chip bad and the long-term working reliability is not high. ;

[0007] 4) The motor drive circuit board and the motor part are installed together, and the installation form of the motor part is limited in product applications; similarly, the structural form of the motor drive circuit board is also limited, making it difficult to realize low-voltage high-current drive

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