Starting method for brushless rotary motor

Abstract

A method of starting an electric brushless rotating machine is provided. At Steps S1 and S2, initial magnetization respectively are carried out for shifting the rotor at its free pausing state by forced commutation to a desired location to start the forward rotation at the maximum torque. At Step S3, the energization at single-phase is conducted with the rotor and the stator having a positional relationship for permitting generation of the maximum torque after the forced commutation or the second the initial magnetization. An induced voltage at the not-energized phase is measured by the forced commutation and used for determining the location of the rotor. Step S4 follows where a normal action of the energization is carried out. Therefor, it can obtain a large starting torque even when a rotor position detecting element is not used, and which can effect, reliably or with a high probability, normal rotation when a forced commutation is performed.

Description

technical field [0001] The present invention relates to a starting method of a brushless rotating electrical machine, in particular to a starting method of a brushless rotating electrical machine suitable for generating large torque during starting. Background technique [0002] In a brushless motor that is a rotating electrical machine, the energization to the three-phase stator coils is sequentially switched every time the rotor rotates by an electrical angle of 120° to rotate the rotor. A conventional brushless motor generally has a position detection element such as a Hall element for detecting the rotational position of a rotor. In recent years, brushless motors that do not use position detection elements have been proposed in response to demands for miniaturization of brushless motors. [0003] For example, in the brushless motor described in Japanese Patent Publication No. 5-24760, in view of the fact that energization is performed between two different phases in seq...

AI Technical Summary

Problems solved by technology

[0009] In this way, at the stop positions p3 and p6, starting torque does not occur, and even if it occurs, it is small. Therefore, it is sometimes impossible to start the brushless motor.

Especially when the load connected to the brushless motor is large and a large starting torque is required, it is easy to become a problem

For example, in an electric motor for starting an internal combustion engine (engine), since the friction of the engine is large, even if a motor with a large capacity is used, it often happens that a sufficient starting torque cannot be obtained.

In addition, at the stop positions p4 and p5, the rotor reverses, so the induced voltage required for rotor position detection cannot be obtained, and the normal energization cannot be performed.

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