KR20160092605A

KR20160092605A - method of driving BLDC motor for starting current reduction

Info

Publication number: KR20160092605A
Application number: KR1020150013187A
Authority: KR
Inventors: 정대원
Original assignee: 호남대학교 산학협력단
Priority date: 2015-01-28
Filing date: 2015-01-28
Publication date: 2016-08-05

Abstract

A method of driving a BLDC motor driving apparatus including a motor driver for driving a BLDC motor and a control unit for outputting a switching control signal by a motor driver, the method comprising: Controls the starting operation section in which the BLDC motor is started and the normal operation section to be applied after the start operation section and controls the start operation section to apply a constant gain or a different gain from the gain applied to the normal operation section . According to the driving method of the BLDC motor, by increasing the starting current of the BLDC motor by suppressing the rise of the starting current of the BLDC motor by preventing the breakage of the power switching element by improving the durability and by soft starting, It prevents the rise and helps to operate the machine load stably.

Description

[0001] The present invention relates to a method of driving a BLDC motor,

The present invention relates to a starting current reduction driving method of a BLDC motor, and more particularly, to a starting current reduction driving method of a BLDC motor capable of suppressing a rise in starting current and capable of stable speed control.

BLDC motors are widely used as driving devices for mechanical loads in blowing fans, pumps, machine tools and the like. A conventional BLDC motor driving apparatus converts a DC power into a DC power using a single phase (or three-phase) AC power source, converts the DC power into an AC power having a predetermined square wave voltage by using a switch of a motor driver The BLDC motor is driven and the duty ratio of the PWM pulse is varied for controlling the speed.

In order to control the speed of the motor, a hole sensor is attached to the inside or outside of the motor, and a speed sensor that detects the position of the rotor magnetic pole of the BLDC motor from the Hall sensor, .

On the other hand, in order to control the on / off of the switching elements of the motor driver so as to follow the target speed command value and to reduce the cost of the sensors and the like, a sensorless method, And a method of controlling the speed of the BLDC motor is also used. An example thereof is disclosed in Korean Patent No. 10-0189122.

The sensor type or sensorless method described above is controlled so as to follow the speed command value (target operation speed).

On the other hand, in the case of such a BLDC motor, when the current is excessively supplied to follow the target speed at the time of the initial start-up, the power switching element may be damaged or the life of the motor winding element may be shortened.

The present invention has been made in order to solve the above problems of the present invention, and it is an object of the present invention to provide a motor control apparatus and a control method thereof, And to provide a starting current reduction driving method of a BLDC motor.

According to an aspect of the present invention, there is provided a method for driving a BLDC motor, the method including: driving a BLDC motor; driving the BLDC motor driving device including a control unit outputting a switching control signal; Wherein the control unit distinguishes between a start-up operation period in which the BLDC motor is started and a normal operation period to be applied after the start-up operation period, and the start-up operation period is limited to a constant current or less A gain different from the gain applied to the normal operation section is applied.

Preferably, the gain of the startup section is set to be smaller than the gain of the normal operation section.

Also, the gain of the start-up operation period is constantly applied.

According to the driving method of the BLDC motor according to the present invention, by changing the gains at the time of the initial start and the normal operation, increase of the starting current of the BLDC motor is suppressed to prevent the breakage of the power switching element to improve the durability, Thereby preventing a sudden increase in speed, thereby enabling stable operation of the machine load.

1 is a diagram showing a motor driving apparatus to which the starting current reduction driving method of the present invention is applied,
FIG. 2 is a detailed block diagram of the control unit of FIG. 1,
3 is a graph showing a gain value applied when the motor is operated according to time.

Hereinafter, a starting current reduction driving method of a BLDC motor according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing a motor driving apparatus to which the driving method of the present invention is applied, and FIG. 2 is a detailed block diagram of the control unit of FIG.

1 and 2, the BLDC motor driving apparatus 100 includes a motor driver 110, a converter 130, a current detecting unit 141, a hall sensor 143, and a control unit 150.

The converter 130 is connected to the three-phase AC power source, and charges the current to the smoothing capacitor 133 according to a control signal of the control unit 150 to generate a DC power source.

The voltage detector 135 detects the voltage value charged in the capacitor 133 and provides the detected voltage value to the control unit 150.

A reactor denoted by reference numeral 137 boosts commercial AC power and supplies it to the converter 130.

The reactor 137 stores AC power by on / off operation of a switching element constituting the converter 130, and supplies the AC power to the converter 130, thereby performing a boosting operation.

The reactor 137 is also used for power factor correction of the AC power source and for restricting the harmonic current between the commercial AC power source and the converter 130.

The converter 130 converts commercial AC power to DC power.

The converter 130 includes a plurality of switching elements, and converts the commercial AC power supplied through the reactor 137 to DC power by on / off operation of the switching elements.

In the case where the commercial AC power source is a three-phase AC power source, the converter 130 has a pair of upper and lower switching elements connected in series to each other, and three pairs of upper and lower switching elements are connected in parallel do.

Diodes are connected in anti-parallel to each switching element.

When input from the control unit 150 to the gate terminal of the switching element of the converter 130, each switching element performs a switching operation. Thus, the power factor is controlled, and the commercial AC power is converted into DC power and output.

The smoothing capacitor 133 is connected to the output terminal of the converter 130.

The DC power generated by the converter 130 is applied to the motor driver 110 by the control unit 150.

The motor driver 110 has a plurality of switching elements for motor drivers, and supplies a smoothed DC power to the motor (M) 10 by on / off operation of the switching elements.

The motor driver 110 has a pair of upper arm switching elements and lower arm switching elements connected in series to each other, and a total of three pairs of upper arms and lower arm switching elements are connected in parallel to each other. Diodes are connected in anti-parallel to each switching element.

When the switching control signal from the control unit 150 is input to the gate terminal of the switching element of the motor drive 110, each switching element performs a switching operation. Thus, three-phase AC power having a predetermined frequency is output.

The three-phase AC power outputted from the motor driver 110 is applied to each phase of the motor 10. Here, the motor 10 has a stator and a rotor, and alternating current power of a predetermined frequency is applied to the coils of the stator of each phase, so that the rotor rotates.

The current detection unit 141 detects a current supplied to the motor 10 through a power supply line from the motor driver 11 to the motor 10 and provides the detected current to the control unit 150.

The current detector 141 may be a current sensor, a current transformer (CT), a shunt resistor, or the like.

Reference numeral 143 denotes a Hall sensor 143 for detecting the speed of the motor.

The operation unit 171 can set a supported function such as a key for setting the operation or stop of the motor 10.

The control unit 150 controls the switching operation of the motor driver 110 when the operation unit 171 selects the operation ON, that is, when the operation of the motor 10 is set.

The control unit 150 includes a speed calculator 151 for calculating a rotational speed from a signal output from the hall sensor 143, a main controller 155 for controlling the motor driver 110, And a gain gain recording unit 156.

The gain recording unit 156 is provided with an initial start gain application unit 156a in which a first gain value as an initial start gain value is recorded and a normal operation gain application unit 156b in which a second gain value, ).

The main controller 155 controls the proportional-plus-integral (PI) controller 155a to use a value recorded in the gain logger 156 to apply mutually different gain values for the start-up driving period and the normal driving period when the motor 10 is running, To control the motor driver 110. [

Here, the start-up operation period is set to a predetermined time value in advance.

3, the main controller 155 sets the first gain value (G) for the start-up operation period T1, which is the initial operation period of the motor 10, with respect to the gain value G to be applied to the PI controller 155a A is applied to the motor and the driving of the motor 10 is controlled by applying a second gain value B which is set higher than the first gain value A in the normal operation period T2 after the initial startup operation.

Alternatively, the main control unit 155 controls the motor 10 while keeping the current to be less than or equal to a constant current in the start-up driving period T1. In the normal operation period T2, the current detected by the current detecting unit 141 And the second gain value set to follow the target rotation speed by using the speed value calculated by the speed calculating unit 151 to adjust the driving duty of the switching element of the motor driver 110 in a proportional integral control manner .

It is needless to say that the second gain value can be variably configured to be applied in accordance with the detected speed.

The startup operation section T1 is a section for aligning the position of the rotor of the motor 10 while the motor 10 is started so as to gradually reach the target speed command value to make the soft start, And the speed control gain is set to be much smaller than the gain of the normal operation section (T2).

Further, since the start-up operation period T1 is a period during which only the constant current is supplied, the gain thereof may be constant.

According to the driving method of the BLDC motor described above, by changing the gains at the time of the initial start-up and the normal operation, it is possible to prevent breakdown of the power switching element by suppressing the rise of the starting current of the BLDC motor to improve the durability, Thereby preventing a sudden increase in speed, thereby enabling stable operation of the machine load.

110: motor driver 130: converter
141: Current detection unit 143: Hall sensor
150: control unit

Claims

A driving method of a BLDC motor driving apparatus including a motor driver for driving a BLDC motor and a control unit for outputting a switching control signal by the motor driver,
The control unit distinguishes between a start-up operation period in which the BLDC motor is started and a normal operation period to be applied after the start-up operation period, and the start-up operation period is limited to a current or less, And a gain different from a gain to be applied to the BLDC motor is applied.

The starting current reduction driving method of a BLDC motor according to claim 1, wherein a gain of the startup operation section is set to be smaller than a gain of the normal operation section.

2. The starting current reduction driving method of a BLDC motor according to claim 1, wherein the gain of the starting operation section is constant.