KR20180082128A - Apparatus and method for controlling a start of BLDC motor using detection of phase voltage - Google Patents

Abstract

Disclosed are a method and a device for controlling activation of a brushless DC (BLDC) motor using a phase voltage detection which forcibly arranges a location of a rotor when a BLDC motor initially starts, and then performs a phase switching, and operates as a sensorless mode if a back-electromotive force of a phase to which a voltage is not applied, is detected and stabilized within a setting value. The disclosed brushless DC motor activation control device comprises: a rectifying unit which rectifies and smooths AC powers to supply the same as DC powers; a BLDC motor which has a rotor; an inverter which converts the DC powers supplied from the rectifying unit into a three-phase AC power (U, V, W) in a pulse form having a temporary variable frequency and supplies the same to the BLDC motor; a terminal voltage detecting unit which detects terminal voltages of each phase (U, V, W) from the three-phase AC power supplied to the BLDC motor; and a control unit which forcibly arranges a location of the rotor, and, when the arrangement of the rotor is completed, performs a phase switching for acceleration, detects a back-electromotive force of a phase, to which a voltage is not applied, through the terminal voltage detecting unit, performs a phase switching by predetermined times until the detected back-electromotive force value is within a predetermined setting value, and, if the detected back-electromotive force value is within a predetermined setting value, controls the inverter by the sensorless mode.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless DC motor start control method and apparatus using phase voltage detection,

The present invention relates to a brushless direct current motor start control method and apparatus using phase voltage detection, and more particularly, to a brushless direct current motor start control method and apparatus using a brushless direct current (DC) phase DC motor start control method and apparatus using the phase voltage detection to perform the phase change and to operate in the sensorless mode when the counter electromotive force of the phase in which the voltage is not applied is detected and stabilized within the set value .

Normally, a stator of a BLDC (Brushless Direct Current) motor uses an armature that forms a current by flowing a current through a coil, and a rotator uses a permanent magnet formed by repeated N and S poles . In order for the BLDC motor to rotate continuously, it is necessary to form a continuous rotor system of the BLDC motor. In order to form a continuous rotor system, the commutation of the current flowing in the coil of each phase of the armature must be made at an appropriate point. For the conversion, the position of the rotor must be accurately recognized. The conversion here is to change the current direction of the motor stator coil so that the rotor can rotate.

In order to operate the BLDC motor smoothly, it is necessary to precisely match the position of the rotor and the switching point of the phase current, and a device for detecting the position of the rotor is required for this purpose. Generally, A position detection sensor such as a Hall sensor, a resolver device, or an encoder is used. However, since such a position detection sensor has a problem in that manufacturing cost is increased and a driving circuit is complicated, A method for detecting the position of the rotor was sought.

As a result, an electric circuit for detecting the position of the rotor by using the counter electromotive force of the BLDC motor is widely used, and an operation mode for detecting the position of the rotor by using an electric circuit instead of the position detection sensor is referred to as a sensorless operation mode do.

However, in the sensorless operation control method of the conventional BLDC motor, the position information of the rotor is indispensably required to drive the BLDC motor.

If a voltage is applied to an arbitrary stator winding without knowing the position information of the rotor, an overcurrent flows, which causes a large torque ripple, and there is a risk of permanent magnet magnetization of the rotor due to overcurrent.

Further, a rotor position detecting device is required for smooth operation of the BLDC motor, and manufacturing cost increases due to the rotor position detecting device.

Korean Patent Publication No. 10-2016-0056622 (Publication date: May 20, 2016)

SUMMARY OF THE INVENTION An object of the present invention to solve the above-mentioned problems is to provide a BLDC motor in which the position of a rotator is forcibly aligned at the time of initial operation of the BLDC motor and then a phase change is performed and a counter electromotive force And to operate in a sensorless mode when the detected value is stabilized within a set value.

According to an aspect of the present invention, there is provided an apparatus for starting up a brushless DC motor using phase voltage detection, comprising: a rectifier for rectifying and smoothing an AC power source and supplying the same to a DC power source; A BLDC motor having a rotor; An inverter for converting the DC power supplied from the rectifying part into pulse-type three-phase AC power (U, V, W) having an arbitrary variable frequency and supplying the DC power to the BLDC motor; A terminal voltage detector for detecting a terminal voltage of each phase (U, V, W) from a three-phase AC power source supplied to the BLDC motor; And a controller for performing a phase change for acceleration when the alignment of the rotor is completed by forcibly aligning the position of the rotor and a counter electromotive force And performs a phase change at a predetermined number of times until the detected counter electromotive force value becomes within a predetermined value and controls the inverter in a sensorless mode when the detected counter electromotive force value is within a predetermined value .

Also, the control unit may determine the phase change point by comparing the detected counter electromotive force value with a predetermined value.

The control unit compares the detected counter electromotive force value with a preset value, and performs a phase change when the detected counter electromotive force value is out of a preset value, until the detected counter electromotive force value becomes within a predetermined set value Phase conversion can be performed.

According to another aspect of the present invention, there is provided a brushless direct current motor start control method using phase voltage detection, comprising: (a) forcibly aligning a rotor position of a BLDC motor through an inverter; (b) performing a phase change of the BLDC motor through the inverter; (c) detecting a counter electromotive force of the phase to which the terminal voltage detection unit is not applied; (d) performing a phase change at a predetermined number of times until the detected counter electromotive force value is within a predetermined value; And (e) controlling the inverter in a sensorless mode when the detected counter electromotive force value is within a predetermined value.

In the step (d), the control unit may determine the phase change point by comparing the detected counter electromotive force value with a preset value.

In the step (d), the controller compares the detected counter electromotive force value with a preset value, performs a phase change when the detected counter electromotive force value is out of a predetermined value, And the phase change is performed until it is within the value.

According to the present invention, it is possible to detect the position of a rotor of a BLDC motor using counter electromotive force without a rotor position detecting device.

Further, it is possible to detect the position of the motor rotor by using only the back electromotive force without additional circuit configuration for measuring the phase current of the motor.

In addition, it is possible to reduce the startup failure rate by controlling with a small current in the initial startup phase of the motor.

And, the probability of start failure can be reduced through accurate and quick alignment of the rotor.

1 is a block diagram showing a main configuration of a motor rotor control apparatus according to an embodiment of the present invention.
2 is a diagram showing an example of the circuit configuration of the brushless DC motor start control device according to the embodiment of the present invention.
3 is a diagram showing a detailed configuration example of a terminal voltage detecting unit applied to the present invention.
FIG. 4 is a flowchart illustrating a method of controlling the start-up of a brushless DC motor using phase-voltage detection according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating voltages and frequencies that vary during initial operation of a BLDC motor according to an exemplary embodiment of the present invention. Referring to FIG.
6 is a diagram showing current waveforms according to the rotor position and the phase change timing of the stator winding of the present invention.
FIG. 7 is a rear end unipolar PWM pattern diagram applied to the present invention, and FIG. 8 is a terminal voltage pattern diagram of a brushless DC motor when the rear end unipolar PWM pattern of FIG. 7 is used.
9 is a diagram illustrating a process of acquiring a preset value in the brushless DC motor start control method using the phase voltage detection according to the embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between . Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

If any part is referred to as being "on" another part, it may be directly on the other part or may be accompanied by another part therebetween. In contrast, when a section is referred to as being "directly above" another section, no other section is involved.

The terms first, second and third, etc. are used to describe various portions, components, regions, layers and / or sections, but are not limited thereto. These terms are only used to distinguish any moiety, element, region, layer or section from another moiety, moiety, region, layer or section. Thus, a first portion, component, region, layer or section described below may be referred to as a second portion, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified and that the presence or absence of other features, regions, integers, steps, operations, elements, and / It does not exclude addition.

Terms indicating relative space such as "below "," above ", and the like may be used to more easily describe the relationship to other portions of a portion shown in the figures. These terms are intended to include other meanings or acts of the apparatus in use, as well as intended meanings in the drawings. For example, when inverting a device in the figures, certain portions that are described as being "below" other portions are described as being "above " other portions. Thus, an exemplary term "below" includes both up and down directions. The device can be rotated by 90 degrees or rotated at different angles, and terms indicating relative space are interpreted accordingly.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

1 is a block diagram showing a main configuration of a brushless DC motor start control apparatus according to an embodiment of the present invention.

1, a brushless DC motor start control apparatus 100 according to the present invention includes a BLDC motor 110, an inverter 120, a controller 130, a rectifier 140, and a terminal voltage detector 150 .

The BLDC motor 110 has a rotor and is supplied with power from the inverter 120 to rotate the rotor to provide a rotating force.

Here, the BLDC motor 110 has a winding with three coils for generating an inductance component. In other words, a BLDC motor is a structure in which there is no insulation conductor such as a carbon brush for transmitting electric power, a motor is provided in a motor shaft, a coil is provided on the inner wall surface of the motor case, The brushes are not needed as they are supplied to the wall-mounted coils.

The inverter 120 converts the DC power supplied from the rectifying unit 140 into pulse-type three-phase AC power (U, V, W) having an arbitrary variable frequency and supplies it to the BLDC motor 110. In other words, the inverter 120 converts the DC voltage into a three-phase AC voltage and supplies it to the BLDC motor 110. At this time, each of the power switching elements Q1 to Q6 is connected to the three-phase (U, V, W) winding of the inverter 120 as shown in FIG. In other words, the inverter 120 includes a three-phase switching device, for example, an upper three-phase FET and a lower three-phase FET.

The control unit 130 forcibly aligns the position of the rotor and performs phase switching for acceleration when the alignment of the rotor is completed, phase, and the inverter 120 is controlled in a sensorless mode when the detected counter electromotive force value is within a preset value, do.

Also, the control unit 130 may determine the phase change point by comparing the detected counter electromotive force value with a predetermined value.

The control unit 130 compares the detected counter electromotive force value with a preset value and performs phase switching when the detected counter electromotive force value is out of the preset value, until the detected counter electromotive force value is within the predetermined value For example, phase switching can be performed about six times.

The rectifying unit 140 rectifies and smoothes the AC power supply and supplies the DC power to the rectifier unit 140.

The terminal voltage detector 150 detects the terminal voltages of the phases U, V and W from the three-phase AC power supplied to the BLDC motor 110.

When the motor 110 is initially driven, the control unit 130 controls the BLDC motor 110 such that an alignment vector for rotating the rotor in the aligning direction and a zero vector for reducing the rotation speed of the rotor are applied to the BLDC motor 110 So that the inverter 120 can be controlled.

When the motor 110 is in a stopped state, the control unit 130 may perform an alignment process for moving the rotor to a predetermined specific position, a forced magnetic drive for forcibly driving the motor by generating a rotating magnetic field in the motor, And a sensorless control process of acquiring the position information of the rotor by using the counter-electromotive force and controlling the motor by sensorless operation when the counter-electromotive force is generated in the forced-driven motor, the operation of the BLDC motor 110 can be controlled.

Also, the control unit 130 sets all the three-phase switches at the top of the inverter 120 to ON, or turns the three-phase switches at the bottom of the inverter 120 ON, So that the vector is applied to the BLDC motor 110.

The controller 130 applies an alignment vector to the BLDC motor 110 through the inverter 120 to apply a zero vector to the BLDC motor 110 when the rotor rotates in the alignment direction, The rotation vector is applied to the BLDC motor 110 so as to reduce the rotation speed of the rotor, so that the rotational speed of the rotor It is stopped at the self-alignment position.

2 is a diagram showing an example of the circuit configuration of the brushless DC motor start control device according to the embodiment of the present invention.

Referring to FIG. 2, in the brushless direct current motor start control apparatus 100 according to the present invention, the inverter 120 is connected to three-phase (U, V, W) windings of power switching FETs Q1 to Q6 ). That is, the inverter 120 can use a conventional switching circuit composed of six switching elements Q1 to Q6 and a diode.

The terminal voltage detector 150 detects the terminal voltages of the phases U, V and W from the three-phase AC power supplied to the BLDC motor 110 and inputs them to the controller 130.

The controller 130 may detect the zero crossing point ZCP of the counter electromotive force according to the terminal voltages of the phases U, V and W detected by the terminal voltage detector 150 to obtain the position information of the rotor.

The controller 130 may be implemented as a microprocessor that controls the pattern of the PWM signal supplied to the inverter 30 so that the overcurrent is not supplied to the BLDC motor 110 by controlling the voltage application time.

The PWM signal generator 132 generates a pattern of the PWM signal by the output of the controller 130 and supplies it to the inverter 120.

At this time, a power factor compensating capacitor (not shown) may be connected in parallel on the connection line between the inverter 120 and the three-phase windings of the BLDC motor 110. That is, the power factor compensating capacitor C can be connected in parallel between the V phase and the W phase, between the W phase and the U phase, respectively, between the U phase and the V phase of the three phases at the output terminal of the inverter 120. The capacitance of the power factor compensating capacitor C may be set to be the same as the magnitude of the inductance component of the BLDC motor 110.

The control unit 130 applies the switching driving signals of the power switching elements Q1 to Q6 to the inverter 120. [ That is, the control unit 130 controls the switching operation of each switching element Q1 to Q6 of the inverter 120 according to a user's operation to control the start, operation and speed of the BLDC motor 110, (Q1 to Q6) and applies the switching drive signal to the inverter (120).

3 is a diagram showing a detailed configuration example of a terminal voltage detecting unit applied to the present invention.

3, the terminal voltages of the phases U, V and W of the BLDC motor 110 are divided by the resistors R1 and R2 and input to the A / D input port 134 of the controller 130. At this time, a Zener diode may be separately added to the A / D input port 134 so that the voltage value divided by each of the resistance distribution circuits (R1, R2) can be confined within the A / D input voltage range of each phase terminal voltage .

In the sensorless operation period, in order to detect the zero crossing point (ZCP) of the counter electromotive force from the terminal voltage of each phase, half of the terminal voltage of each phase (U, V, W) To the digital input port 136 of the control unit 130. The control unit 130 receives the comparison result through the comparator 52,

FIG. 4 is a flowchart illustrating a method of controlling the start-up of a brushless DC motor using phase-voltage detection according to an embodiment of the present invention.

4, the controller 130 of the brushless DC motor start control system according to the present invention forcibly aligns the rotor position of the BLDC motor 110 through the inverter 120 (S410) .

That is, the control unit 130 may apply the alignment vector to the BLDC motor 110 through the inverter 120 to align the rotor. Here, the alignment vector means an alignment current applied to the BLDC motor 110 so that the rotor rotates in a specific direction to align the rotor.

Next, the controller 130 performs phase switching of the BLDC motor 110 through the inverter 120 (S420).

That is, the controller 130 supplies current to any two phases of the BLDC motor 110 to forcibly align the rotor position, and when the alignment of the rotor is completed, the BLDC motor 110, And performs phase switching while performing synchronous acceleration for accelerating the rotor of the BLDC motor 110 to a predetermined speed. FIG. 5 is a diagram illustrating voltages and frequencies that vary during initial operation of a BLDC motor according to an exemplary embodiment of the present invention. Referring to FIG. For example, if a current is supplied to the U-V phase winding when the rotor is forcedly aligned, the phase is switched to the U-W phase to supply current to the U-phase phase winding. When the rotational speed of the rotor reaches a speed at which the counter electromotive force can be detected from the stator winding of the BLDC motor 110, the controller 130 controls the magnitude of the voltage applied to the BLDC motor 110 as shown in FIG. 5 So that the phases of the rotor magnetic field and the stator magnetic field are switched.

In the sensorless operation mode, a voltage greater than a voltage suitable for the load applied to the BLDC motor 40 is applied to the BLDC motor 40 in order to reduce the startup failure rate when the BLDC motor 40 is initially started. Therefore, in the section synchronously accelerating the BLDC motor 40, the phase transition timing of the stator winding is delayed as shown in Fig. 6 (a). 6 is a diagram showing current waveforms according to the rotor position and the phase change timing of the stator winding of the present invention. 6 (a) shows a case where the voltage application time to the stator winding is delayed with respect to the rotor position, in which the phases of the counter electromotive force and the phase current do not coincide with each other and the magnitude of the phase current in the latter half of the phase current becomes excessively large .

6 (b) shows a case where the voltage application time to the stator winding is fast with respect to the rotor position, in which the phases of the counter electromotive force and the phase current do not coincide with each other and the magnitude of the phase current in the first half of the phase current becomes excessively large .

Next, the terminal voltage detector 150 detects a counter electromotive force on the voltage-unapplied phase (S430).

At this time, the control unit 130 can determine the phase change point by comparing the detected counter electromotive force value with a preset value. FIG. 7 is a rear end unipolar PWM pattern diagram applied to the present invention, and FIG. 8 is a terminal voltage pattern diagram of a brushless DC motor when the rear end unipolar PWM pattern of FIG. 7 is used. 8, when the PWM is OFF in a period in which the counter electromotive force e of the phase in which no voltage is applied (hereinafter referred to as the OFF phase) is increased when the rear end unipolar PWM pattern is used, V_off is as follows.

On the other hand, according to the ON / OFF state of the V_off PWM in the period in which the counter electromotive force (e) of the OFF state falls,

Where V is the magnitude of the DC voltage across the inverter 30.

In the period in which the counter electromotive force (e) rises, V_off has a smaller value than V_off in the period in which the counter electromotive force (e) falls.

As shown in Equation (1), it can be seen that the zero voltage is proportional to 1.5 times the OFF-phase counter electromotive force (e). On the other hand, in the period when the counter electromotive force (e) falls, counter electromotive force information appears on the OFF phase terminal voltage based on V / 2 or V.

Therefore, in the period in which the counter electromotive force e rises, the values of the resistance distribution circuits R1 and R2 are adjusted so that the V_off value falls within the A / D input range of the controller 130 in the resistance distribution circuits R1 and R2 of FIG. The signal transmitted to the A / D input port 134 includes the back electromotive force signal included in the V_off without significant attenuation.

On the other hand, in the period in which the counter electromotive force e falls, the values of the resistance distribution circuits R1 and R2 are adjusted so that the V_off value falls within the A / D input range of the controller 130 in the resistance distribution circuits R1 and R2 of FIG. The signal transmitted to the A / D input port 134 has a value in which the back electromotive force signal included in V_off is largely attenuated.

When the BLDC motor 110 rotates at low speed, the counter electromotive force value has a small value.

Therefore, when the rear end unipolar PWM pattern is used, relatively accurate counter electromotive force information can be detected from the OFF terminal voltage in a period in which the counter electromotive force (e) on the OFF state rises. In a system with a large load fluctuation at a low speed such as a compressor, a relatively accurate phase change point can be obtained by integrating the counter electromotive force detected from the terminal voltage at OFF.

8, the control unit 130 determines whether the counter electromotive force of the OFF state is rising (refer to FIG. 8). When the counter electromotive force rises, the control unit 130 integrates the counter electromotive force, Can be determined.

Next, the control unit 130 performs phase switching at a predetermined number of times until the detected counter electromotive force value is within a preset value (S440).

That is, the control unit 130 compares the detected counter electromotive force value with a preset value, and performs a phase change when the detected counter electromotive force value is out of a preset value, until the detected counter electromotive force value is within a predetermined set value For example, the phase change is performed about 6 times. In order to control the speed with Closeloop, it is necessary to find a zero crossing point. Therefore, it is difficult to obtain sufficient speed by only 3 times of U phase, V phase and W phase. Phase conversion.

The control unit 130 controls the inverter 120 in the sensorless mode when the detected back EMF value is within a predetermined value (S450).

That is, when the phase change point of the BLDC motor 110 is determined, the control unit 130 detects whether the counter electromotive force detection is stabilized from the terminal voltage of each phase based on the frequency of the voltage applied to the current rotor, Mode, and if it is not the sensorless switching step, it is fed back to the phase switching step to perform phase switching.

Here, the preset value may be the maximum voltage value and the minimum voltage value of each phase (U, V, W) obtained through the process as shown in FIG. 9 is a diagram illustrating a process of acquiring a preset value in the brushless DC motor start control method using the phase voltage detection according to the embodiment of the present invention. As shown in Fig. 9, the maximum value and the minimum value of each step with respect to the U-phase, the V-phase and the W-phase are measured and determined as a reference value as a reference.

The controller 130 performs phase switching and detects a zero crossing point ZCP of the counter electromotive force from the terminal voltages of each phase and outputs the phase switching and phase control based on the zero crossing point ZCP information to the BLDC motor 110 In the sensorless operation mode.

As described above, according to the present invention, when the position of the rotor is forcibly aligned at the time of initial operation of the BLDC motor, the phase is switched, and the counter electromotive force of the phase where no voltage is applied is detected, The brushless DC motor start control method and apparatus using the phase voltage detection can be realized.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims and their equivalents. Only. It is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. .

100: Brushless DC motor start control device
110: BLDC motor
120: Inverter
130:
140: rectification part
150: terminal voltage detecting section

Claims (6)

A rectifying unit for rectifying and smoothing the AC power supply and supplying the same to a DC power supply;
A BLDC motor having a rotor;
An inverter for converting the DC power supplied from the rectifying part into pulse-type three-phase AC power (U, V, W) having an arbitrary variable frequency and supplying the DC power to the BLDC motor;
A terminal voltage detector for detecting a terminal voltage of each phase (U, V, W) from a three-phase AC power source supplied to the BLDC motor; And
The phase of the rotor is aligned forcibly, and when the alignment of the rotor is completed, a phase change for acceleration is performed, and a counter electromotive force of a phase to which no voltage is applied through the terminal voltage detector A control unit for controlling the inverter in a sensorless mode when the detected counter electromotive force value is within a preset value;
Wherein the brushless direct current motor starting control device includes:
The method according to claim 1,
Wherein the control unit compares the detected counter electromotive force value with a preset value to determine a phase change point.
The method according to claim 1,
Wherein the control unit compares the detected counter electromotive force value with a preset value and performs a phase change when the detected counter electromotive force value is out of a preset value, Wherein the brushless direct current motor start control device uses the phase voltage detection.
(a) forcibly aligning the rotor position of the BLDC motor via the inverter;
(b) performing a phase change of the BLDC motor through the inverter;
(c) detecting a counter electromotive force of the phase to which the terminal voltage detection unit is not applied;
(d) performing a phase change at a predetermined number of times until the detected counter electromotive force value is within a predetermined value; And
(e) controlling the inverter in a sensorless mode when the detected counter electromotive force value is within a preset value;
Wherein the brushless DC motor start control method comprises:
5. The method of claim 4,
Wherein the control unit determines the phase change point by comparing the detected counter electromotive force value with a preset value in the step (d).
5. The method of claim 4,
In the step (d), the controller compares the detected counter electromotive force value with a preset value and performs a phase change when the detected counter electromotive force value deviates from a predetermined value, and when the detected counter electromotive force value is within a predetermined set value And the phase of the brushless DC motor is controlled so that the brushless DC motor starts to be turned on.

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