WO2018117499A1

WO2018117499A1 - Method and device for driving brushless dc motor using voltage compensation

Info

Publication number: WO2018117499A1
Application number: PCT/KR2017/014324
Authority: WO
Inventors: 김상훈; 김원석; 김태완; 박푸른샘; 안경원; 이성준
Original assignee: 한온시스템 주식회사
Priority date: 2016-12-23
Filing date: 2017-12-07
Publication date: 2018-06-28
Also published as: KR20180074213A; KR102552538B1; CN109757125A

Abstract

The present invention relates to a method and a device for driving a BLDC motor using a voltage compensation, wherein, when a BLDC motor mounted in a vehicle is driven, the DC voltage applied to the motor is detected, and the duty ratio is compensated for in proportion to the amount of variation of the DC voltage such that the same voltage applied to the motor is maintained, thereby guaranteeing that a constant voltage is applied to the motor regardless of the amount of variation of the DC voltage. A BLDC motor driving device according to the present invention may comprise: a BLDC motor that operates when a rated voltage is applied; a rectification portion for rectifying and smoothing AC power and thereby converting the same into DC power, in order to supply the BLDC motor with power; an inverter for converting the DC power into three-phase (U, V, W) AC power according to a PWM control signal and supplying the same to the BLDC motor; a voltage detection portion for detecting voltage of the DC power; a voltage compensation portion that, when the voltage detected by the voltage detection portion is varied, calculates a compensation duty ratio corresponding to the varied voltage; and a control portion for transferring a PWM control signal corresponding to the compensation duty ratio to the inverter. According to the present invention, even if the DC voltage applied to the BLDC motor is unstable, the three-phase AC voltage applied to the motor can be maintained constantly.

Description

Method and apparatus for driving brushless DC motor using voltage compensation

The present invention relates to a method and apparatus for driving a brushless DC motor using voltage compensation. More particularly, the present invention relates to a method for driving a brushless direct current (BLDC) motor mounted on a vehicle to detect a direct current voltage applied to a motor. Brushless using voltage compensation, which compensates for duty ratio by the amount of voltage change so that the voltage applied to the motor remains the same so that a constant voltage can be applied to the motor regardless of the amount of change in the DC voltage. A motor and method for driving a direct current motor.

In general, a brushless DC motor mounted in a vehicle operates by receiving an AC voltage converted from an AC voltage through a rectifier circuit.

The voltage input to a brushless DC motor is often unstable. When the input voltage of the motor becomes unstable, the output (current, rotational speed and torque) of the motor also becomes unstable. In particular, the instability of the current may cause damage to the motor, and the performance of the Electro Magnetic Compatibility (EMC) may be degraded.

The brushless DC motor is controlled by a rotational speed by a proportional plus integral (PI) speed controller. The PI speed controller compares the command speed with the actual speed, and increases the voltage applied to the motor when the actual speed is low and decreases the voltage applied to the motor when the actual speed is high.

At this time, the PI speed controller increases or decreases the voltage by using a pulse width modulation (PWM) signal. To increase the voltage, increase the PWM duty, and to decrease the voltage, reduce the PWM duty.

When the DC voltage Vdc converted from the AC voltage suddenly changes, the voltage actually input to the motor also changes rapidly. If the voltage input to the motor changes rapidly, the current flowing to the motor also changes rapidly.

Therefore, there is a problem that adverse effects are also caused to the product to which the BLDC motor is applied and its neighbors.

An object of the present invention for solving the above-described problems, when driving a BLDC motor mounted on a vehicle, by detecting a DC voltage applied to the motor to compensate the duty ratio by the amount of the DC voltage is changed to the motor The present invention provides a method and apparatus for driving a brushless DC motor using voltage compensation such that a constant voltage can be applied to a motor regardless of a variation in a DC voltage by maintaining a voltage applied to the same.

Brushless DC motor drive device according to the present invention for achieving the above object, BLDC motor that operates when a rated voltage is applied; A rectifier for rectifying and smoothing AC power to DC power to supply power to the BLDC motor; An inverter for converting the DC power into three-phase (U, V, W) AC power according to a PWM control signal and supplying the DC power to the BLDC motor; A voltage detector detecting a voltage of the DC power supply; A voltage compensator configured to calculate a compensation duty ratio corresponding to the changed voltage when the voltage detected by the voltage detector is changed; And a controller for transmitting a PWM control signal corresponding to the compensation duty ratio to the inverter.

In addition, the inverter may supply a rated voltage corresponding to a value obtained by multiplying the voltage of the DC power by the compensation duty ratio to the BLDC motor.

The voltage compensator may calculate the compensation duty ratio by dividing the rated voltage by the changed voltage when the voltage of the DC power source is changed.

On the other hand, the brushless DC motor driving method according to the present invention for achieving the above object is a BLDC motor driving method that operates when a rated voltage is applied, (a) the rectifying unit rectifies and smoothes the AC power source to the DC power source Converting; (b) a voltage detector detecting a voltage of the DC power supply; (c) calculating, by a power compensation unit, a compensation duty ratio corresponding to the changed voltage when the detected voltage is changed; (d) the control unit transmitting a PWM control signal corresponding to the compensation duty ratio to the inverter; And (e) an inverter converting the DC power into a three-phase AC voltage corresponding to the compensation duty ratio and supplying the DC power to the BLDC motor according to the PWM control signal.

In the step (e), the inverter may supply the BLDC motor with a rated voltage corresponding to a value obtained by multiplying the voltage of the DC power by the compensation duty ratio.

The voltage compensating unit may calculate the compensation duty ratio by dividing the rated voltage by the changed voltage when the voltage of the DC power supply is changed.

According to the present invention, even when the DC voltage applied to the BLDC motor is unstable, the three-phase AC voltage applied to the motor can be kept constant. As a result, the BLDC motor can operate stably.

In addition, the stable control of the BLDC motor can increase the stability of the overall vehicle system.

And stable motor control does not generate unnecessary noise.

1 is a configuration diagram schematically showing the configuration of a brushless DC motor driving apparatus according to an embodiment of the present invention.

2 is a diagram illustrating an example of a circuit configuration of a brushless DC motor driving apparatus according to an embodiment of the present invention.

3 is a flowchart illustrating an operation of a brushless DC motor driving method using voltage compensation according to an exemplary embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and like reference numerals designate like elements throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated.

When a portion is referred to as being "above" another portion, it may be just above the other portion or may be accompanied by another portion in between. In contrast, when a part is mentioned as "directly above" another part, no other part is involved between them.

Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited to these. These terms are only used to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, the first portion, component, region, layer or section described below may be referred to as the second portion, component, region, layer or section without departing from the scope of the invention.

The terminology used herein is for reference only to specific embodiments and is not intended to limit the invention. As used herein, the singular forms “a,” “an,” and “the” include plural forms as well, unless the phrases clearly indicate the opposite. As used herein, the meaning of "comprising" embodies a particular characteristic, region, integer, step, operation, element and / or component, and the presence of other characteristics, region, integer, step, operation, element and / or component It does not exclude the addition.

Terms indicating relative space such as "below" and "above" may be used to more easily explain the relationship of one part to another part shown in the drawings. These terms are intended to include other meanings or operations of the device in use with the meanings intended in the figures. For example, if the device in the figure is reversed, any parts described as being "below" of the other parts are described as being "above" the other parts. Thus, the exemplary term "below" encompasses both up and down directions. The device can be rotated 90 degrees or at other angles, the terms representing relative space being interpreted accordingly.

Unless defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Commonly defined terms used are additionally interpreted to have a meaning consistent with the related technical literature and the presently disclosed contents, and are not interpreted in an ideal or very formal sense unless defined.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Referring to FIG. 1, the BLDC motor driving apparatus 100 according to the present invention may include a BLDC motor 110, an inverter 120, a controller 130, a rectifier 140, a voltage detector 150, and a voltage compensator ( 160).

The BLDC motor 110 performs a rotation operation when a rated voltage is applied. To this end, the BLDC motor 110 includes a rotor, and receives three-phase (U, V, W) AC power from the inverter 120 to rotate the rotor to provide rotational force.

Here, the BLDC motor 110 has a winding having three phases of a coil for generating an inductance component. In other words, the BLDC motor has no insulated conductor such as a carbon brush for transmitting electric power. The magnet is attached to the motor shaft and has a coil on the inner wall of the motor case. When the coil is powered, the magnet rotates, and thus the motor shaft to which the magnet is attached rotates, thus eliminating the need for a brush.

The inverter 120 converts the DC power supplied from the rectifier 140 into a three-phase (U, V, W) AC power in a pulse form having an arbitrary variable frequency and supplies the DC power to the BLDC motor 110. That is, the inverter 120 converts a direct current (DC) voltage into a three-phase alternating current (AC) voltage and supplies it to the BLDC motor 110.

In this case, the inverter 120 is connected to each of the power switching elements (Q1 ~ Q6) as shown in Figure 2 to the winding of the three phase (U, V, W). That is, the inverter 120 includes a three-phase switching element. For example, the inverter 120 may include an upper three-phase FET and a lower three-phase FET.

In addition, the inverter 120 may supply the BLDC motor 110 with a rated voltage Vz corresponding to a value obtained by multiplying the voltage V _DC of the DC power supply by the duty ratio r _D according to Equation 1 below. .

In Equation 1, Vz denotes a rated voltage, V _DC denotes a voltage of a DC power supply, and r _D denotes a duty ratio.

The rectifier 140 rectifies and smoothes the AC power to convert the DC power into DC power to supply power required for the operation of the BLDC motor 110.

The voltage detector 150 detects the voltage of the DC power source converted through the rectifier 140.

When the voltage detected by the voltage detector 150 varies, the voltage compensator 160 calculates a compensation duty ratio corresponding to the changed voltage.

That is, the voltage compensator 160, in order to maintain the voltage applied to the BLDC motor 110 is kept constant, if the voltage of the DC power supply changes even a little, using the equation (1) to change the rated voltage to the changed voltage By dividing to calculate the compensation duty ratio.

The controller 130 transmits a PWM control signal corresponding to the compensation duty ratio to the inverter 120 to control the voltage applied to the BLDC motor 110 to be kept constant.

In addition, when the BLDC motor 110 is in a stopped state, the controller 130 may move the rotor to a predetermined specific position, and force the motor to be driven by generating a rotating magnetic field in the motor in which the rotor is aligned. When the counter electromotive force is generated in the driving process and the forcibly driven motor, the operation of the BLDC motor 110 may be controlled by a sensorless control process of acquiring the position information of the rotor using the counter electromotive force to control the motor in a sensorless manner.

Then, the controller 130 turns on all three-phase switches on the upper end of the inverter 120, or turns on all three-phase switches on the lower end of the inverter 120 to zero (0). The vector may be controlled to be applied to the BLDC motor 110.

2 is a diagram illustrating an example of a circuit configuration of a BLDC motor driving apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 2, in the BLDC motor driving apparatus 100 according to the present invention, the inverter 120 has respective power switching elements FETs Q1 to Q6 connected to windings of three phases (U, V, and W). do. That is, the inverter 120 may use a conventional switching circuit composed of six switching elements Q1 to Q6 and a diode.

Although not shown, a terminal voltage detection unit (not shown) for detecting the terminal voltage of each phase (U, V, W) from the three-phase AC power supplied to the BLDC motor 110 and inputting it to the controller 130 is further illustrated. It may include.

The controller 130 may acquire the position information of the rotor by detecting the zero crossing point ZCP of the counter electromotive force according to the terminal voltage of each phase (U, V, W) detected by the terminal voltage detector.

In addition, the controller 130 may be implemented as a microprocessor controlling a pattern of the PWM signal supplied to the inverter 120 by controlling the voltage application time so that the overcurrent is not supplied to the BLDC motor 110.

The PWM signal generator 132 generates a PWM signal corresponding to the compensation duty ratio under the control of the controller 130 and supplies it to the inverter 120.

In this case, a power factor correction capacitor (not shown) may be connected in parallel on the connection line between the inverter 120 and the three-phase winding of the BLDC motor 110. That is, three power factor correction capacitors C may be connected in parallel between U and V phases, between V and W phases, and between W and U phases in three phases at the output terminal of the inverter 120. In addition, the capacitance of the power factor correction capacitor C may be set to be the same as that of the inductance component of the BLDC motor 110.

The controller 130 applies the switching driving signals of the respective power switching elements Q1 to Q6 to the inverter 120. That is, the controller 130 controls the switching operation of each switching element (Q1 ~ Q6) of the inverter 120 to control the start, operation and speed of the BLDC motor 110 according to the user's operation, each switching element A switching driving signal for switching Q1 to Q6 is generated and applied to the inverter 120.

3 is a flowchart illustrating an operation of a method of driving a BLDC motor using voltage compensation according to an exemplary embodiment of the present invention.

Referring to FIG. 3, in the BLDC motor driving apparatus 100 according to the present invention, first, the rectifying unit 140 rectifies and smoothes AC power and converts the DC power into DC power (S310).

Subsequently, the voltage detector 150 detects the voltage of the DC power supply and transmits the detected voltage to the voltage compensator 160 (S320).

In this case, when the detected voltage of the DC power is changed, the voltage compensator 160 calculates a compensation duty ratio corresponding to the changed voltage (S330).

That is, the voltage compensator 160 changes the rated voltage by using Equation 1 when the voltage of the DC power source changes even a little, so that the three-phase AC voltage applied to the BLDC motor 110 is kept constant. The compensation duty ratio is calculated by dividing by the received voltage.

For example, when the rated voltage Vz is 3 V and the voltage V _DC of the direct current (DC) power supply is 10 V, the compensation duty ratio r _D is 30% (0.3). That is, when the AC power is externally applied and the voltage V _DC of the DC power converted through the rectifying circuit is 10V and the duty ratio r _D is 30% (0.3), the BLDC motor 110 The rated voltage Vz applied is 3V.

At this time, when the voltage (V _DC ) of the DC (DC) power supply is suddenly changed from 10V to 15V, the voltage compensator 160 converts the rated voltage (Vz) 3V to the voltage of the DC (DC) power supply using Equation (1). (V _DC ) divided by 15V to calculate the compensation duty ratio (r _D ) 20% (0.2).

Subsequently, the controller 130 transmits a PWM control signal corresponding to the compensation duty ratio to the inverter 120 (S340).

Accordingly, the inverter 120 supplies power of the three-phase AC voltage corresponding to the compensation duty ratio to the BLDC motor 110 according to the PWM control signal (S350).

That is, the inverter 120 according to the PWM control signal, the rated voltage (Vz) 3V corresponding to a value of the voltage (V _DC ) 15V of the _DC power supply multiplied by the compensation duty ratio (r _D ) 20% (0.2) 3V. To supply the BLDC motor 110.

In this case, the controller 130 may detect a zero crossing point (ZCP) and perform a sensorless operation mode for controlling the phase switching and the rotational speed of the BLDC motor 110 based on the zero crossing point (ZCP) information.

Voltage compensation logic according to an embodiment of the present invention can implement a stable motor control regardless of the variation of the DC power applied to the motor. Therefore, this voltage compensation logic is different from a power supply stabilization circuit that only removes noise components. For example, a power stabilization circuit alone is not sufficient for voltages that maintain 12V after the input voltage surges from 10V to 12V. In this case, using the BLDC motor driving apparatus and method according to an embodiment of the present invention, even if the input voltage of the motor changes, it is possible to always apply only a constant rated voltage to the BLDC motor.

Therefore, according to the present invention, even if the input voltage is unstable, the voltage applied to the motor is always kept constant to enable stable motor control. In addition, it is possible to increase the stability of the overall vehicle system through a stable motor control. And stable motor control algorithm does not generate unnecessary noise.

As described above, according to the present invention, when driving a BLDC motor mounted on a vehicle, the DC voltage applied to the motor is detected to compensate for the duty ratio by the amount of the DC voltage fluctuating so that the voltage is applied to the motor. By maintaining the same, it is possible to realize a BLDC motor driving method and apparatus using voltage compensation, in which a constant voltage can be applied to the motor regardless of the amount of change in the DC voltage.

As those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features, the embodiments described above should be understood as illustrative and not restrictive in all aspects. Should be. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. .

The present invention can be used in the industry of manufacturing a vehicle equipped with a BLDC motor.

Claims

A BLDC motor operating when a rated voltage is applied;

A rectifier for rectifying and smoothing AC power to DC power to supply power to the BLDC motor;

An inverter for converting the DC power into three-phase (U, V, W) AC power according to a PWM control signal and supplying the DC power to the BLDC motor;

A voltage detector detecting a voltage of the DC power supply;

A voltage compensator configured to calculate a compensation duty ratio corresponding to the changed voltage when the voltage detected by the voltage detector is changed; And

A controller for transmitting a PWM control signal corresponding to the compensation duty ratio to the inverter;

Brushless DC motor drive device comprising a.
The method of claim 1,

And the inverter supplies the rated voltage corresponding to the value of the voltage of the DC power multiplied by the compensation duty ratio to be applied to the BLDC motor.
The method of claim 1,

And the voltage compensator is configured to calculate the compensation duty ratio by dividing the rated voltage by the changed voltage when the voltage of the DC power supply is changed.
BLDC motor driving method that operates when the rated voltage is applied,

(a) rectifying the rectifying and smoothing the AC power source into DC power;

(b) a voltage detector detecting a voltage of the DC power supply;

(c) calculating, by a voltage compensator, a compensation duty ratio corresponding to the changed voltage when the detected voltage is changed;

(d) the control unit transmitting a PWM control signal corresponding to the compensation duty ratio to the inverter; And

(e) an inverter converting the DC power into a three-phase AC voltage corresponding to the compensation duty ratio and supplying the DC power to the BLDC motor according to the PWM control signal;

Brushless DC motor driving method comprising a.
The method of claim 4, wherein

In the step (e), the inverter, the brushless DC motor driving method for supplying a rated voltage corresponding to the value of the voltage of the DC power multiplied by the compensation duty ratio to the BLDC motor.
The method of claim 4, wherein

In the step (c), when the voltage of the DC power supply fluctuates, dividing the rated voltage by the variable voltage to calculate the compensation duty ratio, brushless DC motor driving method.