KR101979453B1 - Air conditioner and controlling method for the same - Google Patents

Abstract

An object of the present invention is to provide an air conditioner and a control method thereof for efficiently improving the power consumption of the compressor and increasing the start-up success rate of the compressor.
According to an aspect of the present invention, there is provided an air conditioner having an indoor unit and an outdoor unit connected to the indoor unit, the air conditioner comprising: a compression mechanism reciprocating to compress the refrigerant; an electric motor driving the compression mechanism; A control unit for setting a current to be applied to the electric motor and for applying the set electric current to the electric motor by controlling the inverter unit; .
Wherein the control unit applies a predetermined first starting current to the electric motor when the electric motor starts, and when the electric motor fails to start, applies a second starting current larger than the first starting current to the electric motor, Restart the motor.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an air conditioner,

The present invention relates to an air conditioner and a control method thereof.

The air conditioner includes an indoor unit installed in a room and an outdoor unit for supplying the refrigerant to the indoor unit. At least one indoor unit may be connected to the outdoor unit, and the outdoor unit includes components such as a compressor and a heat exchanger.

The air conditioner may operate in a cooling or heating operation depending on the flow of the refrigerant compressed in the compressor. In detail, when the air conditioner operates in the cooling mode, the refrigerant compressed in the compressor of the outdoor unit may be a liquid refrigerant of high temperature and high pressure by the heat exchanger of the outdoor unit. When the high-temperature and high-pressure liquid is supplied to the indoor unit, the refrigerant may expand and evaporate due to the indoor unit heat exchanger. The temperature of the ambient air is lowered by the vaporization phenomenon, and the indoor air can be supplied to the indoor space while the indoor fan is rotated.

When the air conditioner is operated in a heating mode, gas refrigerant of high temperature and high pressure can be supplied from the compressor to the indoor unit. The high-temperature and high-pressure gaseous refrigerant supplied to the indoor unit can be liquefied by the high-temperature and high-pressure gaseous refrigerant by the heat exchanger of the indoor unit. At this time, the energy released by the liquefaction phenomenon raises the temperature of the surrounding air, and warm air can be supplied to the indoor space while the indoor fan is rotating.

Meanwhile, the compressor may include an electric motor for providing a rotational force for compressing the refrigerant, and a motor drive circuit for controlling a current input to the electric motor. The electric motor may include a stator and a rotor rotated with respect to the stator. In the electric motor, a relative position of the rotor with respect to the stator is detected, and a current is inputted to a position corresponding to the relative position.

The position of the rotor can be estimated and detected based on the current value input to the electric motor. And the electric motor can be controlled based on the detected position value and the speed command for the electric motor. The drive for detecting the relative position of the rotor without any sensor is called sensorless driving.

Regarding such an air conditioner, the applicant of the present invention has conventionally filed a patent application (hereinafter, referred to as prior art). The information of the preceding documents is as follows.

1. Publication No. (Disclosure Date): Published Patent Publication No. 10-2004-0003700 (Jan. 13, 2004)

2. Title of the invention: Operation control method of air conditioner

In the prior art, an initial alignment step of aligning the rotor to a set position in order to reduce an error between an estimated position and an actual position of the rotor, which is generated in the sensorless drive process, and gradually increasing the RPM of the motor A step of estimating a position of the rotor based on the position of the rotor based on the counter electromotive force detected from the motor that is started in the step of estimating the position, A sensorless driving step is performed.

On the other hand, the compressors of the preceding documents are started with a fixed starting current irrespective of the load. At this time, even when the load is low, since the compressor is started with a fixed driving current, there is a problem in that it is inefficient in the power consumption of the compressor.

In addition, the outdoor unit can be installed in an outdoor space, which is generally outdoor. For this reason, the compressor installed in the outdoor unit can be affected by weather and outdoor temperature. For example, in an outdoor low temperature environment, the air conditioner can be operated in a heating operation. At this time, the dynamic viscosity (or kinematic viscosity) of the oil retained in the compressor can be increased due to the low temperature. If the kinematic viscosity of the oil increases, there may arise a problem that the compressor starts up due to an increase in the initial starting load of the compressor.

SUMMARY OF THE INVENTION It is a first object of the present invention to provide an air conditioner and a control method thereof that more efficiently improve the power consumption of a compressor.

A second object of the present invention is to provide an air conditioner and a control method thereof for increasing the start-up success rate of a compressor.

In particular, the present invention proposes an air conditioner and its control method for increasing the startup success rate of a compressor by allowing the compressor starting current to be re-selected on the basis of the number of starts when the compressor fails to start.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a control method for a hybrid vehicle including a compression mechanism, an electric motor for driving the compression mechanism, and a controller for setting a current to be applied to the electric motor, And a control unit for applying the controlled current to the electric motor.

Wherein the control unit applies a predetermined first starting current to the electric motor when the electric motor starts, and when the electric motor fails to start, applies a second starting current larger than the first starting current to the electric motor, Restart the motor.

The control unit according to the second aspect of the present invention counts the number of starting times of the electric motor and gradually increases the magnitude of the starting current supplied to the electric motor in proportion to the counted number of starts.

The third invention is characterized in that the set value is 10% of the starting current applied to the electric motor at a previous start.

The fourth invention further includes a memory in which the starting current information according to the number of starting times of the electric motor is stored in a table form. The control unit refers to the memory and restarts the motor by applying a starting current corresponding to the number of starting times to the electric motor at the time of restarting the electric motor.

The fifth invention is characterized in that the starting current is within a rated current range in which the electric motor can be driven.

A sixth aspect of the present invention is characterized in that, when the electric motor is initially driven, a starting current applied to the electric motor is the smallest value among the rated current ranges.

The control unit of the seventh invention attempts to restart the motor by applying the maximum rated current to the motor for a set number of times when the starting current applied to the motor reaches the maximum rated current in the rated current range during the restarting process .

The control unit of the eighth invention stops the restarting when the number of starts exceeds the preset number of times and outputs a warning via the display unit provided in the indoor unit.

The control unit according to the ninth aspect of the invention restarts the electric motor after waiting for a set time when the starting fails.

According to a tenth aspect of the present invention, there is provided a method of controlling a motor vehicle, comprising: increasing a count variable in which the number of times of starting the motor is recorded; incrementing the counted number of times of starting counting to match table information stored in the memory; Increasing the count variable if the motor fails to start, and restarting the motor with a starting current corresponding to the incremented count variable with reference to the memory. The magnitude of the starting current applied to the motor is gradually increased in proportion to the counted number of starting times.

The eleventh invention is characterized in that the starting current applied to the electric motor is within a rated current range in which the electric motor can be driven.

A twelfth aspect of the present invention is characterized in that, when the electric motor is initially driven, a starting current applied to the electric motor is the smallest value among the rated current ranges.

According to the present invention, starting from the smallest value of the rated current range that can start the compressor, is attempted. Therefore, there is an advantage that the power consumption of the compressor is improved.

In addition, since the starting current to be applied to the compressor is selected based on the startup range table information pre-stored in the memory, the compressor can automatically perform the restart without manual control of the user or service man even if the startup fails.

Also, since the compressor restarts while gradually increasing the starting current, the startup failure rate due to the starting load can be reduced. Accordingly, there is an advantage that the maintenance requirement is reduced and the convenience of the user is improved.

1 is a configuration diagram of an air conditioner according to an embodiment of the present invention.
2 is a view showing an air conditioning system according to an embodiment.
3 is a block diagram showing a circuit configuration of a motor driving apparatus according to an embodiment.
4 is a table showing driving current information stored in a memory according to an exemplary embodiment.
5 is a block diagram showing a configuration of a control unit according to an embodiment.
6 is an exemplary diagram illustrating a start-up algorithm of an electric motor according to an embodiment of the present invention.
7 is a flow chart illustrating a start-up algorithm of a compressor according to one embodiment.
8 is a graph showing a current change according to a compressor start algorithm according to an embodiment.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. It is to be understood, however, that the spirit of the invention is not limited to the embodiments shown and that those skilled in the art, upon reading and understanding the spirit of the invention, may easily suggest other embodiments within the scope of the same concept.

<Configuration of the air conditioner>

1 is a configuration diagram of an air conditioner according to an embodiment of the present invention.

Referring to FIG. 1, an air conditioner 10 according to an embodiment of the present invention includes an indoor unit 500 for discharging harmonized air into the room, an outdoor unit 100 connected to the indoor unit 500, May be included.

The outdoor unit 100 and the indoor unit 500 are connected to each other through a refrigerant pipe so that the cold air can be discharged from the indoor unit 500 to the room according to the circulation of the refrigerant. The plurality of indoor units 500 may be connected to the outdoor unit 100 in a plurality of ways.

Also, the air conditioner 10 may correspond to the indoor unit 500 and the outdoor unit 100 one by one, as shown in the figure. In another embodiment, the air conditioner may include a plurality of indoor units and at least one indoor unit connected to the plurality of indoor units.

The indoor unit 500 may include a cave for discharging the heat-exchanged air through the indoor heat exchanger 510. The discharge port may be provided with a wind direction adjusting unit that can open and close the discharge port and control the direction of the discharged air. The indoor unit 500 can regulate the amount of air discharged from the discharge port. For example, a plurality of vanes may be installed in a plurality of air inlets and a plurality of air outlets. The vane may open / close at least one of the plurality of air inlets and / or the plurality of air outlets, and guide the flow direction of the air.

In addition, the indoor unit 500 may further include an input unit for inputting a display unit and setting data for displaying the operation state and setting information of the indoor unit 500. [ When the user inputs a driving operation command of the air conditioner through the input unit, the outdoor unit 100 can be operated in the cooling mode or the heating mode corresponding to the inputted command. In addition, the outdoor unit 100 supplies the refrigerant to the plurality of indoor units 500, and the air flow direction is guided along the discharge port of the indoor unit 500, so that the indoor environment can be controlled.

[Air conditioning system: configuration of outdoor unit and indoor unit]

2 is a view showing an air conditioning system according to an embodiment.

Referring to FIG. 2, the outdoor unit 100 may include an outdoor heat exchanger 110 for exchanging heat between outdoor air and refrigerant. When the air conditioner 10 is operated in a cooling operation, the outdoor heat exchanger 110 can be operated as a condenser. Therefore, the gaseous refrigerant delivered to the outdoor heat exchanger 110 can be condensed by the outdoor air.

Also, when the air conditioner 10 is operated in a heating operation, the outdoor heat exchanger 110 can operate as an evaporator. Accordingly, the liquid refrigerant transferred to the outdoor heat exchanger 110 can be evaporated by the outdoor air.

The air conditioner 10 may further include an outdoor air blower 120 for blowing outdoor air to the outdoor heat exchanger 110. The outdoor fan 120 may include an outdoor motor 122 when the power is generated and an outdoor fan 121 connected to the outdoor motor 122 to generate a wind power by the power of the outdoor motor 122 have.

The outdoor unit 100 may include an accumulator 140 for extracting the gaseous refrigerant. The accumulator 140 may extract the gaseous refrigerant from the refrigerant flowing into the accumulator 140 and deliver the extracted gaseous refrigerant to the compressor 300.

The outdoor unit 100 may further include a compressor 300 for compressing the gaseous refrigerant extracted from the accumulator 140. The compressor 300 mixes and compresses the refrigerant introduced from the accumulator 140 and the oil introduced from the oil separator 150 to be described later. The indoor heat exchanger 510 and the outdoor heat exchanger The heat exchanger 110 can be made to flow. The compressor (300) may include an inverter compressor capable of varying the capacity.

Meanwhile, the compressor 300 may include a compression mechanism (not shown) that compresses the refrigerant to a predetermined pressure and an electric motor (330 of FIG. 3) that drives the compression mechanism. In this embodiment, the compression mechanism can be understood as a reciprocating mechanism such as a piston, for example.

The electric motor 310 may include the stator and the rotor. An AC power source or a DC power source may be applied to the coil of each phase stator at a predetermined frequency, so that the rotor can rotate. In this embodiment, the electric motor 310 may include a BLDC (Blushless DC) electric motor.

The outdoor unit 100 may include an electric motor drive unit 350 for driving the electric motor 310 included in the compressor 300. The details of the electric motor 310 and the electric motor driving apparatus 350 will be described later.

On the other hand, the dynamic viscosity (hereinafter referred to as kinematic viscosity) of the oil may vary depending on the temperature. For example, the lower the temperature, the greater the kinematic viscosity of the oil. Conversely, the higher the temperature, the lower the kinematic viscosity of the oil. If the kinematic viscosity of the oil increases, the starting load of the compressor may increase. In this case, a higher driving current is required in proportion to the starting load for starting the compressor. Variations of the driving current of the compressor 300 according to the oil kinematic viscosity will be described later.

The outdoor unit 100 may further include an oil separator 150 for separating refrigerant containing oil discharged from the compressor 300. The oil separator 150 may separate the refrigerant and the oil using the mass of the refrigerant and the oil flowing into the oil separator 150. The oil separator 150 may discharge the separated refrigerant to any one of the indoor heat exchanger 510 and the outdoor heat exchanger 110. In addition, the oil separator 150 may guide the separated oil to the compressor 300.

The outdoor unit 100 may further include a four-way valve 130 for switching the flow of the refrigerant discharged from the compressor 300 and separated from the oil separator 150. The refrigerant separated from the oil separator 150 by the four-way valve 130 may be delivered to any one of the outdoor heat exchanger 110 and the indoor heat exchanger 510. For example, when the air conditioner 10 performs the heating operation, the four-way valve 130 adjusts the flow path so that the refrigerant separated from the oil separator 150 is transferred to the indoor heat exchanger 510 . In contrast, when the air conditioner 10 performs the cooling operation, the four-way valve 130 adjusts the flow path so that the refrigerant separated from the oil separator 150 is transferred to the outdoor heat exchanger 110 side . Accordingly, the refrigerant passing through the oil separator 150 flows through the four-way valve 130 and flows into either the outdoor heat exchanger 110 or the indoor heat exchanger 510 depending on the operation state of the air conditioner .

The air conditioner may further include an outdoor expansion valve (not shown). The outdoor expansion valve may expand the refrigerant that has not passed through the outdoor heat exchanger (110). That is, when the air conditioner operates in a heating operation, the outdoor expansion valve may expand the refrigerant that has passed through the outdoor heat exchanger (110). The outdoor expansion valve may include an electronic expansion valve (EEV), for example.

Meanwhile, the indoor unit 500 may include an indoor heat exchanger 510 in which indoor air and refrigerant are heat-exchanged. When the air conditioner 10 operates in the cooling mode, the indoor heat exchanger 510 may perform an evaporator function. Therefore, the liquid refrigerant transferred to the indoor heat exchanger 510 can be evaporated by the indoor air.

Further, when the air conditioner 10 operates in a heating operation, the indoor heat exchanger 510 may perform a condenser function. Accordingly, the gaseous refrigerant delivered to the indoor heat exchanger 510 can be condensed by the indoor air.

The indoor unit 500 may further include an indoor blower 520 for blowing indoor air to the indoor heat exchanger 510. The indoor air blower 520 may include an indoor electric motor 522 for generating power and an indoor fan 521 connected to the indoor electric motor 522 and generating a wind power while being rotated by the indoor electric motor 522 have.

 The air conditioner 10 may further include an indoor expansion valve (not shown). When the refrigerant that has passed through the indoor heat exchanger (510) passes through the indoor expansion valve, the indoor expansion valve can expand the refrigerant. That is, when the air conditioner 10 performs cooling operation, the indoor expansion valve may expand the refrigerant that has passed through the indoor heat exchanger. The indoor expansion valve may include an electronic expansion valve (EEV), for example.

[Circuit configuration of drive device of electric motor provided in compressor]

FIG. 3 is a block diagram showing a circuit configuration of a motor driving apparatus according to an embodiment. FIG. 4 is a table showing driving current information stored in a memory according to an exemplary embodiment.

Referring to FIG. 3, the motor driving apparatus 350 may include a rectifying unit 352 for rectifying the input AC power source 351 to DC power. The rectifying unit 352 converts the power input from the input AC power source 351 to DC power and outputs the DC power to the inverter unit 354. The rectifying unit 352 includes a switching device, and can perform a boosting operation, a power factor improvement, and a DC power conversion. Meanwhile, as another example, the rectifying unit 352 may be a diode or the like and perform a rectifying operation without a separate switching operation.

The motor driving apparatus 350 may further include a smoothing capacitor 353 for smoothing the DC power input from the rectifying unit 352 to the inverter unit 354. [ The smoothing capacitor 353 may be disposed between the rectifying part 352 and the inverter part 354. [ The smoothing capacitor 353 may be connected in parallel to the output terminal of the rectifying unit 352. The smoothing capacitor 353 may smooth the ripple voltage (voltage wave) generated in response to the switching frequency while the switching elements in the inverter unit 354 switch. The smoothing capacitor 353 can smoothen a voltage that is rectified by the rectifying unit 352, that is, a voltage that varies depending on a power supply voltage.

The electric motor driving apparatus 350 may further include an inverter unit 354 for converting the DC power into a driving power and applying the DC power to the electric motor 310. The inverter unit 354 may convert the direct current power into the driving power based on an inverter control signal input from a control unit 360, which will be described later. The inverter unit 354 may be disposed between the rectifying unit 352 and the electric motor 310. The inverter unit 354 may be disposed at a front end of the electric motor 310.

The electric motor drive unit 350 may further include a current detection unit 355 for detecting a current supplied from the inverter unit 354 to the electric motor 310. The control unit 360 may be a current transducer connected between the interverter 354 and the motor 310 to continuously detect a driving current. The current transducer may detect the driving current and convert it into a voltage signal and transmit it to the control unit 360. The control unit 360 may generate an interrupt signal to sample a voltage signal corresponding to the driving current. As another example, the current detection unit 355 may be replaced by a shunt resistor. The current detection unit 355 may be connected (3p) to detect the current for all three phases. However, as another example, it is also possible that the current detection unit 355 is connected (1p) to detect the drive current only for one phase.

The electric motor driving apparatus 350 may further include a voltage detecting unit 356 for detecting a driving voltage applied to the electric motor 310 from the inverter unit 354. [ Although it has been shown that the voltage detecting unit 356 detects all three-phase voltages, it is also possible to detect only the one-phase driving voltage.

The motor driving apparatus 350 further includes a control unit 360 that can generate a control signal by a PWM (Pulse Width Modulation) method and output a control signal generated by the PWM method to the inverter unit 354 .

The electric motor driving apparatus 350 may further include a memory 358 storing current information for starting the electric motor 310. In detail, in the memory 358, startable rated current range information of the electric motor 310 can be stored in a table form. The range of the rated current may be determined during the initial designing process of the compressor (300) or the motor (310).

Hereinafter, the "rated current range information stored in the form of a table" is referred to as "startup range table information".

4, in the memory 358, information in which a starting current value corresponding to the number of times of starting (or a count variable (count variable)) is recorded may be stored in a table form. For example, when the motor 310 is started for the first time, the count variable may be '1'. The starting current corresponding to the count variable '1' may be the first starting current I1. The first starting current I1 may be the smallest value among the rated current range in which the motor 310 can be driven.

On the other hand, if the motor 310 fails to start up, the control unit 360 may increase the count variable by '1'. The control unit 360 may control the inverter unit 354 to apply the second starting current I2 corresponding to the incremented count variable to the electric motor 310. [ The second starting current I2 may be a current value that is increased by a predetermined magnitude in comparison with the first starting current I1. The set size may, for example, mean 10% of the previous starting current. That is, the second starting current I2 may have a current value that is increased by 10% of the first starting current I1.

When the electric motor 310 fails to start, the count variable may increase and the control unit 360 may refer to the memory 358 to calculate a current value corresponding to the count variable A current value higher than a current value applied to the electric motor 310).

Meanwhile, in the process of restarting the electric motor 310, the count variable may reach the first limit value corresponding to the maximum rated current value of the electric motor 310. In this case, the control unit 360 may attempt to restart while applying the maximum rated current value to the electric motor 310 until the count variable reaches a second limit value that is greater than the first limit value. The second limit value may be a value arbitrarily set by the designer in the initial process.

When the count variable reaches the second limit value, the control unit 360 may stop the restart operation of the electric motor 310. [ A warning may be displayed on the display unit to indicate that the operation of the air conditioner (10) is restricted. The starting current is variably controlled in accordance with the number of starting times of the electric motor 310 will be described later in more detail.

[Configuration of control unit of motor drive circuit]

5 is a block diagram showing a configuration of a control unit according to an embodiment.

Referring to FIG. 5, the control unit 360 may include a speed controller 361 for receiving the speed command and the rotor speed and calculating and outputting a current command for reducing the speed error.

The control unit 360 may further include a current controller 363 for receiving the current command and the drive current and calculating and outputting a voltage command for reducing the current error.

The control unit 360 may further include a pulse width modulation controller 365 for generating the inverter control signal based on the voltage command.

The control unit 360 may further include an axis conversion unit 367 for converting the three phases into two phases of the d-q axis.

The control unit 360 may further include a speed calculator 369 for calculating the rotor speed and outputting the calculated speed to the speed controller 361. [

The control unit 360 detects a drive current to generate an inverter control signal and outputs a signal to the U, V, and W phase gates of the three-phase motor through the inverter. At this time, the graph of the phase current can have a sinusoidal waveform.

The speed control unit 361 includes a comparator for comparing the speed command? * M desired by the user with the rotor speed, and a proportional integral controller (PI). The speed controller 361 receives the speed command and the rotor speed, and performs a proportional integration of the speed error to generate a q-axis current command (i * q) and output it to the current controller 363.

The current controller 363 receives the q-axis current command and the d-axis current command i * d generated by the speed controller 361, and generates and outputs a voltage command. The magnitude of the current supplied to the motor 310 can be determined according to the magnitude of the voltage command. The current controller 363 outputs the q-axis voltage command (V * q) to the pulse width modulation controller 365 via the current proportional plus integral controller and the filter. That is, the current controller 363 compares the q-axis current command and the motor drive current with the q-axis detected current iq transformed by the axis transformer 367, and calculates the difference between the q-axis current command and the motor drive current by the current proportional integral controller And outputs the q-axis voltage command (V * q) to the pulse width modulation controller 365 through the filter.

On the other hand, the current control unit 363 outputs the d-axis voltage command (V * d) to the pulse width modulation controller 365 via another current proportional integral controller and a filter through the d-axis current command. That is, the current control section 363 compares the d-axis detection current id that has undergone the axial conversion of the d-axis current command and the motor drive current and outputs the difference therebetween through the current proportional integral controller and the filter to the d- (V * d) to the pulse width modulation control unit 365. [ Here, the voltages and currents are values on a synchronous coordinate system.

The pulse width modulation controller 365 first converts the voltage command of the synchronous coordinate system into the voltage command of the stationary coordinate system (?,?). That is, the pulse width modulation control unit 365 converts (V * d, V * q) into (V * ?, V *?). The pulse width modulation control unit 365 converts the voltage command of the stationary coordinate system to the type of the motor to be driven and outputs the converted voltage command. That is, the pulse width modulation control unit 365 can convert the voltage command in the stationary coordinate system into three-phase voltage commands (V * u, V * v, V * w) and output it to the inverter unit 354.

[Starting algorithm of motor]

6 is an exemplary diagram illustrating a start-up algorithm of an electric motor according to an embodiment of the present invention.

Referring to FIG. 6, the starting algorithm of the electric motor 310 may include an initial alignment step R1, a position estimation step R21, and a sensorless driving step R22.

First, the initial alignment step (R1) may be understood as a step of aligning the position of the rotor to a set position. The motor drive unit 350 may convert input AC power and supply a predetermined voltage or current to the motor 310. The electric motor driving apparatus 350 may apply a current to the rotor of the electric motor 310 to align the rotor to a predetermined position.

Specifically, in the initial alignment step (R1), the rotor provided at a predetermined angle is rotated to cross the stator. Preferably, in the initial alignment step (R1), the rotor and the stator are rotated in an initial alignment state orthogonal to each other. At this time, current supply to the electric motor 310 may be performed for a set time with a predetermined driving current. The first driving current value and the set time value may be previously set in the control unit 360. For example, the first driving current may be 1 [A] and the set time may be 3 minutes.

Next, when the initial alignment step (R1) is completed, the position estimating step (R21, open loop) in which the second driving current is supplied to the motor (310) at a driving frequency corresponding to a first driving frequency interval Step) may be performed. In the position estimation step R21, the driving frequency may gradually increase with time in the first driving frequency interval. That is, the control unit 360 may control the electric motor 310 such that the rotor of the electric motor 310 is gradually increased in the low-speed rotation state. As the speed of the rotor increases, the back electromotive force detection performance in the motor can be improved. Therefore, the position estimation of the rotor can be facilitated.

When the position estimating step R21 is completed, a sensorless driving step R22 may be performed in which the electric motor 310 is controlled based on the position of the rotor detected in the position estimating step. The motor driving apparatus 350 estimates the position of the actual rotor by a sensorless algorithm and can start the motor 310 according to the command speed. In the present embodiment, the sensorless control of the electric motor 310 can be referred to as " start control ". In the sensorless driving step, the second driving current may be applied to the motor 310, and the second driving current may be referred to as a starting current.

On the other hand, the motor 310 (or the compressor 300) may fail to start due to a load on the compressor 300, burnout, or the like. In this case, the control unit 360 may restart the motor 310 by re-executing (or re-operating) the initial alignment step R1 and the position estimation step R2. The number of restarts of the motor 310 may be counted, and at least one of the first drive current and the second drive current may be varied based on the number of times the motor 310 is started. For example, at least one of the first driving current and the second driving current may increase in proportion to the number of starting times as the starting frequency increases.

In the sensorless driving step, a current applied to the electric motor 310 may be detected in the current detection unit 355. Here, the current detected in the sensorless driving step may be a second driving current. The current detected by the current detection unit 355 may be applied to the control unit 360 as a discrete signal in the form of a pulse. The detected current may be used to generate a switching control signal for controlling the inverter unit 354. [

The control unit 360 can estimate the rotor position of the motor 310 based on the current detected by the current detection unit 355 as described above, Can be calculated. Further, based on the estimated position and rotation speed, various control operations are performed to drive the motor 310 according to the speed command to generate a switching control signal having a variable pulse width, And outputs it to the inverter unit 354.

[Starting algorithm of compressor]

7 is a flow chart illustrating a start-up algorithm of a compressor according to one embodiment.

Before describing the starting algorithm of the following compressor, for convenience of explanation, the name of the " second driving current " is replaced with the name of " starting current "

4, 5, and 7, an operation start command may be input to the air conditioner 10 through the input unit. In this case, a start command may be input to the control unit 360 provided in the compressor 300. [

The control unit 360 can initialize the number of start commands (S110). For example, the count of the start command may be set to a count variable, and the value of the count variable may be '1' at the time of initialization.

The control unit 360 may operate as an initial alignment step (S130). The control unit 360 may apply the predetermined first driving current to the electric motor 310 for a first set time. As the first driving current is inputted to the electric motor 310, the rotor of the electric motor 310 may be aligned in a predetermined direction.

When the first set time has elapsed, the control unit 360 may be driven to the position estimation step R2. At this time, the control unit 360 can refer to the memory 358 and apply the starting current (second driving current) corresponding to the set count variable to the electric motor 310 for the second set time. In other words, the control unit 360 may input the starting current to the motor 310 at a driving frequency corresponding to the first driving frequency interval. Accordingly, the control unit 360 can detect the position of the rotor of the electric motor 310 by controlling the current detection unit 355. Meanwhile, when the count variable is 1, the starting current value matching the starting range table information may be the first starting current. The first starting current may be the smallest value among the rated current range in which the electric motor 310 can be driven.

When the first set time has elapsed, the control unit 360 may attempt to enter the sensorless mode (S150). In other words, the control unit 360 can start-up control of the electric motor 310. If the sensorless mode entry is successful, the control unit 360 may perform the sensorless mode until a separate stop command is input (S170).

On the other hand, if the sensorless mode entry fails (S150), the control unit 360 may increase the count variable (S190). In other words, if the startup control fails, the control unit 360 may increase the count variable. For example, at start-up, the control unit 360 may increase the count variable by '1'.

The control unit 360 may refer to the memory 358 and call a starting current value corresponding to the count variable (S200). In detail, the control unit 360 may match the count variable to the starting range table information stored in the memory 358. [ When the count variable is 2, the control unit 360 can recognize the second starting current larger than the first starting current.

The control unit 360 may compare the incremented count variable and the magnitude of the first limit value (S210). In other words, the control unit 360 can check whether the motor's maximum rated current (or the compressor's maximum rated current) of the starting current corresponding to the incremented count variable is exceeded. In this embodiment, as shown in FIG. 4, when the count variable is 4, the fourth starting current I4 corresponding to the count variable is the maximum rated current. Accordingly, when the count variable is '4', it can be understood that the count variable is the first limit value.

When the count variable is &quot; 10 &quot;, the control unit 360 stops the additional restart and displays a warning on the display unit of the air conditioner 10. [ Here, when the count variable is '10', it can be understood that the count variable is a second limit value.

The control unit 360 can restart the electric motor 310 (or the compressor 300) while repeating steps S130 to S210 until the count variable reaches the first limit value.

If the count variable exceeds the first limit value (S210) and the count value is less than the second limit value (S250), the control unit 360 waits for the set time, (Or the compressor 300) can be restarted. For example, the set time may be 3 minutes (S270).

When the count variable reaches the second limit value (S250), the control unit 360 may stop the operation of the air conditioner 10 (S290). Further, a warning can be displayed by controlling the display unit of the air conditioner (10). Accordingly, the user can recognize that the air conditioner 10 has a problem.

8 is a graph showing a current change according to a compressor start algorithm according to an embodiment.

Prior to describing the graphs shown in the drawings, the configuration of the graphs will be described.

The x-axis of the graph represents the time and the y-axis represents the magnitude of the current applied to the motor.

The section (A) of the x-axis means the first starting section, the section (B) means the second starting section, and the section (C) means the third starting section.

Referring to FIG. 8, in the section (A), it can be confirmed that the compressor 300 fails to start due to an increase in startup load. The increase in the starting load can be understood, for example, as an increase in the oil kinematic viscosity due to the decrease in the outdoor temperature.

(B), the compressor is restarted with the starting current by increasing the starting current by one step by the motor starting algorithm. The graph shown here shows that the starting current is increased. On the other hand, it is tried to restart the compressor with the starting current increased by one time in the section (A), but it can be seen that the compressor fails to start.

(C), it can be seen that the compressor 300 is restarted with the starting current increased by one step from the starting current at the time of the previous restart, and the startup is successful.

According to the present embodiment, the compressor 300 tries to start from the lowest level of the rated current range that can be started. Accordingly, there is an advantage that the power consumption of the compressor 300 is improved.

Also, since the compressor 300 selects the starting current using the startup range table pre-stored in the memory 358, the compressor 300 can restart itself even if the startup fails.

In addition, since the compressor 300 restarts while gradually increasing the starting current, the startup failure rate due to the starting load can be reduced. Accordingly, there is an advantage that the maintenance requirement is reduced and the convenience of the user is improved.

Claims (12)

1. An air conditioner having an indoor unit and an outdoor unit connected to the indoor unit,
A compression mechanism for compressing the refrigerant;
An electric motor for driving the compression mechanism;
An inverter unit for applying a driving current to the electric motor;
A current detection unit for detecting a current provided by the inverter unit; And
And a control unit for setting a current to be applied to the electric motor and controlling the inverter unit to apply the set electric current to the electric motor,
The control unit
And counting the number of starting times of the electric motor at the start of the electric motor,
Setting at least one of an initial alignment current for initial alignment of the electric motor, a position estimation of the electric motor and a starting current for sensorless driving to increase as the number of starting times increases,
The initial alignment current is applied to the motor to attempt initial alignment of the motor and the starting current is applied to the motor to attempt position estimation and sensorless drive of the motor,
When the starting of the electric motor fails, the electric motor is attempted to be restarted as long as the number of starting times does not exceed a preset number of times,
The starting current
The motor is within a rated current range at which the motor can be driven,
The control unit
The starting current is determined to be the smallest value among the rated current ranges when the motor starts for the first time,
Wherein when the starting current applied to the motor reaches a maximum rated current in the rated current range during a restart of the motor, the maximum rated current is applied to the motor for a set number of times to attempt to restart the motor. Air conditioner.
delete The method according to claim 1,
The control unit
Wherein the controller increases the startup current by 10% as the number of starting times increases.
The method according to claim 1,
Wherein the starting current information according to the starting number of the electric motor is stored in a table form,
Wherein the control unit, when restarting the electric motor,
And restarts the motor by applying a starting current corresponding to the number of starting times to the motor with reference to the memory.
delete delete delete The method according to claim 1,
Wherein the control unit comprises:
Wherein the air conditioner stops the restart when the number of starts exceeds the preset number of times and outputs a warning through the display unit provided in the indoor unit.
The method according to claim 1,
The control unit, when failing to start,
And restarts the electric motor after waiting for a set time.
A step of inputting a start command to an electric motor; And
Performing start-up of the motor in accordance with the start command
Lt; / RTI &gt;
The step of starting the electric motor
Counting a starting frequency of the electric motor;
Setting at least one of an initial alignment current for initial alignment of the electric motor or a starting current for sensorless drive of the electric motor to increase as the number of starts increases;
Applying the initial alignment current to the motor to attempt initial alignment of the motor;
Applying the starting current to the motor to attempt position estimation and sensorless driving of the motor; And
When the starting of the motor fails, attempting to restart the motor in such a manner that the number of starting times does not exceed a preset number of times
Lt; / RTI &gt;
The starting current
The motor is within a rated current range at which the motor can be driven,
The step of starting the electric motor
The starting current is determined to be the smallest value among the rated current ranges when the motor starts for the first time,
Wherein when the starting current applied to the motor reaches a maximum rated current in the rated current range during a restart of the motor, the maximum rated current is applied to the motor for a set number of times to attempt to restart the motor. A control method of the air conditioner. delete delete

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