KR20080068303A - The structure of the brushless dc motor using a hybrid type roter - Google Patents

Abstract

A structure of a brushless DC motor using a hybrid type rotor is provided to improve the output efficiency of a motor by enhancing a structure and a circuit configuration for removing mutual inductance. A structure of a brushless DC motor using a hybrid type rotor(110) reduces torque ripple of the brushless DC motor of a half-wave conducting type. The hybrid type rotor is divided and arranged on one rotation shaft(111) for each phase. A mutual induced generation braking phenomenon at a stator(120) of a non-excited state is removed by the hybrid type rotor. The stator is also divided for each phase in order to evade a trouble between excited magnetic flux and inertial power of an adjacent stator, which is induced into the stator of the non-excited state.

Description

Structure of the brushless DC motor using a hybrid type roter}

1 is a schematic circuit diagram of a conventional four-phase half-wave energized BLDC motor

2 is a schematic circuit diagram of a conventional three-phase onion energized BLDC motor

3 is a schematic plan view of a conventional four-phase half-wave energized BLDC motor

4 is a schematic cross-sectional view (A-A`) of a conventional four-phase half-wave energized BLDC motor

5 is a plan view (@ L1) of a four-phase half-wave energized BLDC motor according to the present invention.

6 is a cross-sectional view (A-A`) of a four-phase half-wave energized BLDC motor according to the present invention.

7 is a circuit diagram of a four-phase half-wave energized BLDC motor according to the present invention.

<Description of reference numerals for main parts of the drawings>

    110: rotor 111: shaft

    112: magnet (PM) 013: E-wrought iron

    120: stator 121: case

    122: yoke 123: field coil

    024: bracket 130: power transister

    031: upper switch (upper S / W) 032: lower switch (lower S / W)

    [Document 1] KR10-1999-0024346 (LG Electronics Co., Ltd. Gujahong) 1999.06.25 [Document 2] KR10-1998-0006903 (LG Electronics Co., Ltd. Gujahong) 1998.03.03 [Document 3] Book publishing, small motor , Seoul: 1993 Chapter 4 Brushless Motors and Their Uses, 87-108

The present invention relates to a structure of a chainless direct current motor (hereinafter referred to as BLDC motor). A schematic circuit diagram of a general BLDC motor is a BLDC motor composed of a three-phase onion energized circuit (star connection type) shown in FIG. 2 based on a prototype of a BLDC motor composed of a four-phase half-wave energized circuit illustrated in FIG. 1. It is developed and used mainly in a wide range of fields from home appliances to information processing devices. In the excitation sequence, it is generally composed of a two-phase excitation method applied to a stepping motor, and the four-phase half-wave conductive BLDC motor shown in FIG. 1 is switched so that the BLDC motor rotates the rotor continuously by the magnetic force generated in the stator. The element 030 is operated by alternating conduction in four steps (@ 90 °), and the three-phase onion energized BLDC motor shown in FIG. ) Is working by alternating current. In the conventional driving method for reducing torque ripple of a three-phase onion energized BLDC motor, a pulse width modulation (PWM) voltage and a pulse width modulation (PWM) voltage are generated to improve unstable torque generation of a motor generated in a low frequency band due to overcurrent of the initial start-up. There is a driving method that controls the amount of current by adjusting the point of application of DC voltage, and the disappearance point of freewheeling current in the microcomputer that the reverse electromotive force reversed whenever it crosses the zero phase of the common point is controlled in accordance with the zero-EMF signal. There are various circuit techniques such as the driving method to operate the motor more stably by programming to apply the voltage to the other coil by accurately predicting the voltage. Structural torque ripple reduction methods of the motor include a method of skewing a slot of a stator or a magnet of a rotor.

However, the above-described method or structure for driving a BLDC motor is a brake due to self and mutual induction power generation which is inevitably involved in the interaction of a motor operated by generating repulsion and attraction between rotors due to a change in magnetic force of the stator. As a countermeasure for remarkably reducing torque ripple caused by damping phenomenon, there is a problem in that there is a limit.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object thereof is to provide a motor structure that fundamentally reduces torque ripple by using not only a circuit technique of a BLDC motor but also a structural improvement method.

The structure of the BLDC motor according to the present invention is a structural torque ripple reduction method and a surge voltage absorbing circuit (snubber) is energized by a separate rotor and stator arranged separately for each phase on one rotation shaft (one-shaft) It is characterized by consisting of a half-wave energized voltage application circuit utilizing a wheeling current.

Hereinafter, with reference to the accompanying drawings.

3 and 4 show a plan view and a cross-sectional view of a conventional four-phase half-wave energized BLDC motor. 3 shows an initial state of Step 1 in which the coils of L1 and L2 are excited by a two-phase excitation sequence to generate an S pole in the slot part, and the rotor starts to rotate in a clockwise direction. At 2, the coil of L3 is excited and the coil of L1 is opened by the control element. At this time, in the stator of the coil that enters the open phase state, inherent inductance inevitably causes generation voltage due to self and mutual induction, resulting in torque ripple due to severe damping phenomenon. The use of the BLDC motor is very limited and mainly uses the onion energized circuit structure to reduce power generation braking and improve output and coil utilization by mutual induction.

However, even in the onion-powered BLDC motor, power generation braking by mutual induction still remains, and it does not fundamentally block torque ripple caused by magnetic force caused by self-induction.

However, in stepping motors, high-frequency rotation is achieved by reducing the torque ripple by using a circuit technique that mainly dissipates most of the inertia power accumulated in the inductor by the surge voltage absorber circuit using the freewheeling resistor (Rf). It also secures operability.

The structure of the half-wave energized (4 winding-2 phase excitation) BLDC motor according to the present invention is a solution to fundamentally reduce the torque ripple caused by the inductive action.

First, as shown in FIG. 5, a magnet (PM), which causes attraction force in the rotor in response to the magnetic force of the excited stator, is replaced with E-wrought iron to configure the rotor.

So, unlike the onion-powered BLDC motor, which has to maintain the rotational motion by inducing magnetism and repulsive action that caused the attraction of the stator by reverse polarity after zero-cross where the reverse electromotive force is reversed, it is half-wave. When the stator of the energized BLDC motor replaces the magnet that caused the attraction force even during the open phase period with the electro-wrought iron, there is no point of action of the magnetic force that caused the generation braking. The resulting torque ripple is essentially eliminated.

This type of hybrid rotor is already used in stepping motors, but stepping motors have a single-phase stator uneven slot in which the rotor faces a multipolar magnet and a poled electric iron. Precise controllability to secure a predetermined rotation step angle by detent torque is required by inputting only a predetermined pulse required in a state, and a hybrid rotor of a BLDC motor according to the present invention has a stator of a single phase. Is focused on improving the output efficiency by confronting the magnet of the rotor in one-to-one (1: 1) area only.

Here, the hybrid rotor 110 shown in FIG. 5 is composed of six poles in consideration of the weight balance due to the density difference of each material. Accordingly, the opposite stator is three-phase but the same single phase (L1: L1a to L1c). Corresponds to).

As shown in FIG. 6, the reason for separating the stator and the rotor for each phase structurally is as follows: in a single one-yoke like the four-phase half-wave conductive BLDC motor shown in FIG. 3. Even when a hybrid rotor having a structure according to the present invention is used in a conventional motor incorporating a four-phase stator, the magnetic flux of a neighboring stator excited by a two-phase excitation sequence is attempted to form a cross-linked magnetic path through the yoke. This is because it is necessary to prevent trouble with attenuation flux due to self-induction when entering the stator in the state.

Here, the four-phase half-wave conductive BLDC motor according to the present invention shown in FIG. 5 is a plan view of the L1 single-phase coil only, and the rotor is six-pole and operated in 12 steps (@ 30 ° = @ 90 ° / 3). The positions of the stators separated by stars are the same on the plane, but the positions of the opposing magnets are arranged to have a phase difference of 30 ° each.

In particular, the winding names (L1 to L4) indicated by drawing out the dotted lines separately indicate the centerline of the magnets arranged on the rotors which face each other (total of 4 phases) and interact with each other at the starting time of the clockwise rotation. It is shown, Figure 6 shows a cross-sectional state of the BLDC motor accordingly.

And, Figure 7 is used by the deenergization of inertia power accumulated in its induction in the stator of the state (Pf = LI ^2/2) illustrates a four-circuit configuration of the phase half-wave energization type BLDC motor according to the present invention, etc. stepping motor By energizing using the freewheeling diodes D1 to D4 in the same manner as the surge voltage absorption circuit snubber, due to the structural characteristics of the motor according to the present invention, the output efficiency is enhanced.

That is, the magnetic flux attenuating in the inductor in the non-excited state has the opposite polarity as when excited, so that only the attractive force acts on the subsequent magnet of the rotor, thereby obtaining additional forward rotational force.

However, the inertial power causing the torque ripple due to the delay of the voltage application time according to the hysteresis characteristics of the stator-core material is added to the data value accurately calculated using the integrated freewheeling resistor VR1 (Rf) shown in FIG. Accordingly, the high frequency output characteristics are secured by variably dissipating heat in conjunction with the input control device.

And the circuit driving method is the same as the conventional four-phase half-wave energized BLDC motor operated by the two-phase excitation sequence.

In addition, the BLDC motor according to the present invention is charged through the freewheeling diode built in parallel to the switching element (power transistor) because the electromagnetic flow acts only in the ground direction due to mutual induction when the main switch is stopped to stop. It also has excellent regenerative braking function.

The structure of the BLDC motor according to the present invention is to improve the output efficiency of the motor by fundamentally improving the structure and circuit configuration in order to eliminate or utilize the self and mutual induction action that is the main factor of torque ripple compared to the conventional motor structure and driving method It is effective to remarkably improve.

Claims (3)

In providing a motor structure that reduces torque ripple of a half-wave conductionless chainless DC motor, Separating and arranging each phase by using a composite rotor on one rotating shaft; The structure of the BLDC motor to eliminate the mutually induced generation braking phenomenon generated in the stator in the non-excitation state by the hybrid rotor. The method of claim 1, wherein the stator is arranged separately for each phase in order to avoid troubles of excited magnetic flux and inertial power of nearby stators flowing into the stator in an unexcited state. . The method of claim 1, wherein the stator is configured to variably dissipate the inertial power supplied to the surge voltage absorbing circuit in an unexcited state using only an integrated freewheeling resistor in conjunction with an input regulating device. .

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