US 7,459,878 B2 · Method and circuit for controlling sensorless single-phase BLDCM

Abstract

The method and circuit for controlling a sensorless single-phase BLDCM having a stator with a winding are proposed. The provided controlling circuit includes a power supply circuit, an inverter coupled to the winding and the power supply circuit, a BEMF detecting circuit coupled to the winding and the inverter and measuring a BEMF of the winding, and a controller coupled to the power supply circuit, the inverter and the BEMF detecting circuit and analyzing a status of the BEMF to control the BLDCM accordingly. The provided method is based on the motor winding time-sharing theory, and the controller controls the inverter to make the winding used as a driving element with loading current when the absolute value of the BEMF is relatively large and as a sensing element when the absolute value of the BEMF is relatively small.

Claims19

Dependent claims

A controlling method of a brushless DC motor (BLDCM) comprising an inverter, a stator having a winding, a rotor and a controller, wherein a back electromotive force (BEMF) is generated while said rotor rotates, comprising the steps of:

(a) controlling said inverter to let a first current having a first direction flow to said winding so as to rotate said rotor;
(b) cutting off a loop flowing therethrough by said first current in said inverter at a first moment, wherein said first current flows through a flywheel current loop and is degenerated to zero at a second moment;
(c) measuring a terminal voltage of said winding, which is said BEMF, and obtaining a third moment at which said BEMF drops to zero;
(d) adjusting said first moment by said controller according to a relationship between said third moment and said second moment;
and
(e) employing a second current having a second direction to replace said first current at a fourth moment and then repeating steps (a) to (d).

3 more elements

Dependencies are inferred from the claim text.

Method and circuit for controlling sensorless single-phase BLDCM

Life of this patent

Method and circuit for controlling sensorless single-phase BLDCM

Life of this patent

Abstract

Claims19