KR100947609B1 - Motor controller of air conditioner and method of the motor controller - Google Patents

Abstract

The present invention provides a converter for converting commercial AC power into a DC power source, an inverter having a plurality of switching elements and receiving DC power and converting the AC power into an AC power by switching operation of the switching element, and supplying the motor to the motor, A temperature detector for detecting a temperature and controlling the motor to be driven at a set frequency when the detected temperature is less than the first temperature, and when the detected temperature is between the second temperature and the first temperature that is greater than the first temperature, The present invention relates to an electric motor control apparatus for an air conditioner including a control unit for controlling the operation frequency to stop rising or falling. Thereby, the electric motor control apparatus of an air conditioner can drive the electric motor of an air conditioner stably by varying the operating frequency of an electric motor according to the temperature of an electric motor periphery.

Air Conditioner, Electric Motor, Current Detection, Temperature Detection, Target Frequency

Description

Motor controller of air conditioner and control method thereof {Motor controller of air conditioner and method of the motor controller}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control apparatus for an air conditioner and a method of controlling the same, and to set a target frequency of the motor based on temperature and current of the motor control apparatus for overheat prevention control of circuit elements of the motor control apparatus of the air conditioner. It relates to a motor control apparatus for an air conditioner, and a control method thereof.

An air conditioner is a device that is disposed in a room, a living room, an office, or a business store to adjust a temperature, humidity, cleanliness, and airflow of an air to maintain a comfortable indoor environment.

Air conditioners are generally divided into one-piece and separate types. The integrated type and the separate type are functionally the same, but the integrated type integrates the functions of cooling and heat dissipation to install a hole in the wall of the house or hang the device on the window, and the separate type installs an indoor unit that performs cooling / heating on the indoor side and outdoor. On the side, an outdoor unit that performs heat dissipation and compression functions was installed, and two separate devices were connected by refrigerant pipes.

On the other hand, the air conditioner is used for a motor, such as a compressor, a fan, and the motor controller for driving this is used. That is, an electric motor control apparatus which converts commercial AC power into DC power and converts it into AC power of a predetermined frequency is used.

Conventionally, in driving an electric motor of an air conditioner, a temperature is detected and a limit temperature is set therein. When the detected temperature reaches the limit temperature, the operating frequency of the motor is lowered and then returned to the set frequency. Controlled.

However, when the operation frequency of the motor is lowered and then returned to the set frequency again, an abnormality often occurs, and there is a problem that the operation frequency frequently decreases continuously.

An object of the present invention is to provide an electric motor control apparatus for an air conditioner which stably drives an electric motor of an air conditioner by varying the operating frequency of the electric motor in accordance with the temperature around the electric motor of the air conditioner.

The motor control apparatus of the air conditioner according to the embodiment of the present invention for solving the above-mentioned problems and other problems, the converter is provided with a converter for converting a commercial AC power source to a DC power source, a plurality of switching elements and input the DC power source The inverter which converts into AC power and supplies the motor by the switching operation of the switching element, the temperature detector which detects the temperature around the motor, and controls the motor to be driven at the set frequency when the detected temperature is less than the first temperature. And a control unit for controlling to stop rising or falling of an operating frequency of the electric motor when the detected temperature is between the second temperature and the first temperature that is greater than the first temperature.

On the other hand, the motor control apparatus of the air conditioner according to an embodiment of the present invention, the converter for converting a commercial AC power source to a DC power source, and a plurality of switching elements, and receives the DC power source by the switching operation of the switching element An inverter which is converted into a power supply and supplied to the motor, an input current detector for detecting an input current from a commercial AC power supply, and when the detected input current is less than the first current, the motor is controlled to be driven at a set frequency, and the detected input If the current is between the second current greater than the first current and the first current, the control unit for controlling to stop the rise or fall of the operating frequency of the motor.

As described above, the motor control apparatus of the air conditioner according to the embodiment of the present invention can stably drive the motor of the air conditioner by varying the operating frequency of the motor according to the temperature around the motor of the air conditioner. .

In addition, it is possible to stably drive the motor of the air conditioner by varying the operating frequency of the motor in accordance with the input alternating current input to the motor control device of the air conditioner.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

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

Referring to the drawings, the air conditioner 50 is largely divided into an indoor unit (I) and an outdoor unit (O).

The outdoor unit O includes a compressor 2 serving to compress the refrigerant, a compressor electric motor 2b for driving the compressor, an outdoor side heat exchanger 4 serving to radiate the compressed refrigerant, and an outdoor unit. An outdoor blower (5) disposed on one side of the heat exchanger (5) for promoting heat dissipation of the refrigerant, and an outdoor blower (5) for rotating the outdoor fan (5a), and an expansion for expanding the condensed refrigerant. A mechanism (6), a cooling / heating switching valve (10) for changing the flow path of the compressed refrigerant, and an accumulator (3) for temporarily storing the gasified refrigerant to remove moisture and foreign substances and then supplying a refrigerant of a constant pressure to the compressor. And the like.

The indoor unit (I) is disposed inside the indoor heat exchanger (8) performing cooling / heating functions, and the indoor fan (9a) and the indoor disposed at one side of the indoor heat exchanger (8) to promote heat dissipation of the refrigerant. And an indoor blower 9 made of an electric motor 9b for rotating the fan 9a.

At least one indoor side heat exchanger (8) may be installed. The compressor 2 may be at least one of an inverter compressor and a constant speed compressor. In addition, the air conditioner 50 may be configured as a cooler for cooling the room, or may be configured as a heat pump for cooling or heating the room.

On the other hand, the electric motor in the motor control apparatus of the air conditioner according to an embodiment of the present invention may be each electric motor (2b, 5b, 9b) to operate the outdoor fan, compressor or indoor fan shown in the figure.

2 is a block diagram of a motor control apparatus of an air conditioner according to an embodiment of the present invention.

Referring to the drawings, the motor control apparatus 200 of the air conditioner according to an embodiment of the present invention includes a converter 210, an inverter 220, a controller 230, and a temperature detector 240. do. Motor control apparatus 200 of the air conditioner according to an embodiment of the present invention may further include a reactor (L) and a smoothing capacitor (C).

The reactor L is disposed between the commercial AC power supply and the converter 210 to perform power factor correction or boost operation. In addition, the reactor L may perform a function of limiting harmonic currents due to the high speed switching of the converter 210.

The converter 210 converts the commercial AC power passed through the reactor L into DC power and outputs the DC power. In the figure, a commercial AC power source is shown as a single-phase AC power source, but may be a three-phase AC power source. The internal structure of the converter 210 also varies according to the type of commercial AC power. For example, in the case of a single phase AC power supply, a half bridge type converter in which two switching elements and four diodes are connected may be used, and in the case of a three phase AC power supply, six switching elements and six diodes may be used. The converter 210 includes a plurality of switching elements and performs a boosting operation, power factor improvement, and DC power conversion by a switching operation.

The smoothing capacitor C is connected to the output terminal of the converter 210. The converted DC power output from the converter 210 is smoothed. Hereinafter, the output terminal of the converter 210 is referred to as a dc terminal or a dc link terminal. The DC voltage smoothed at the dc stage is applied to the inverter 220.

The inverter 220 includes a plurality of inverter switching elements, and converts the DC power smoothed by the on / off operation of the switching element into a three-phase AC power source having a predetermined frequency and outputs the same. Specifically, the upper arm switching element and the lower arm switching element connected to each other in a pair, a total of three pairs of upper and lower arm switching elements are connected in parallel to each other.

Three-phase AC power output from the inverter 220 is applied to each phase (u, v, w) of the three-phase motor 250. Here, the three-phase electric motor 250 is provided with a stator and a rotor. Each phase AC power of a predetermined frequency is applied to a coil of each stator so that the rotor rotates. The three-phase motor 250 may be a variety of forms, such as BLDC motor, synRM motor.

The controller 230 controls the inverter 220. To this end, the controller 230 may generate and output a switching control signal Sic of the inverter based on the output current output from the inverter 220.

In addition, the controller 230 may control the operating frequency of the motor to vary according to the temperature around the motor detected by the temperature detector 240 described later.

The temperature detector 240 detects the temperature Td around the motor 250. The detected temperature Td is input to the controller 230. The detected temperature td and the operation frequency variation of the motor will be described later with reference to FIG. 3.

Meanwhile, the temperature detector 240 may be an inverter temperature detector that detects temperatures of inverter switching elements. In addition, the temperature detector 240 may be a heat sink temperature detector for detecting the temperature of the heat sink attached to the inverter. In addition, the refrigerant discharge temperature detection unit for detecting the refrigerant discharge temperature of the compressor. In addition, the outdoor unit temperature detection unit for detecting the temperature of the outdoor unit. In addition, the outdoor side heat exchanger temperature detector, or the inlet pipe temperature detector of the outdoor heat exchanger or the outlet pipe temperature detector of the outdoor heat exchanger.

3 is a diagram showing the relationship between the temperature around the motor and the operating frequency of the motor according to the present invention.

Referring to the drawings, when the detected temperature Td is less than the first temperature T1, the controller 230 controls the electric motor 250 to be driven at the set frequency. The set frequency is set based on the load amount calculated in relation to the temperature of the indoor unit, the outdoor temperature and the like. The set frequency value may be determined by the controller 230. According to the determined set frequency, the controller 230 generates an inverter switching control signal Sic and controls the inverter 2206 accordingly. The set frequency may vary depending on whether the motor is started or whether the calculated load amount varies.

Next, when the detected temperature Td is between the second temperature T2 and the first temperature T1 that is greater than the first temperature T1, the controller 230 determines that the actual operating frequency of the motor 250 is increased. Control not to follow the set frequency. That is, by stopping the rising or falling of the actual operating frequency of the motor 250, and controls to operate at a constant operating frequency. That is, by setting the frequency retention period between the first temperature (T1) and the second temperature (T2) to prevent the phenomenon that the operating frequency continues to fall when the operating frequency falls as in the prior art.

Next, when the detected temperature Td is between the third temperature T3 and the second temperature T2 which is larger than the second temperature T2, the controller 230 once the actual operating frequency of the electric motor is a predetermined value. Control to descend. For example, it is controlled to operate by lowering 5Hz from the actual operating frequency. This is to prevent the circuit burnout of the motor controller as the temperature rises.

Next, when the detected temperature Td is equal to or greater than the third temperature T3 which is the threshold value, the control unit 230 controls the electric motor 250 to stop. To this end, the controller 230 stops application of the inverter switching control signal Sic applied to the inverter 220. By this protection operation, it is possible to protect the motor control apparatus such as the inverter 220 including the plurality of switching elements.

As shown in FIG. 3, the controller 230 outputs a switching control signal Sic differently according to the detected temperature Td so as to vary an operating frequency of the motor 250 according to the detected temperature Td.

The controller 230 estimates the speed of the motor based on the output current of the inverter 220, generates a current command value based on the estimated speed and the set speed (set frequency), and generates a voltage based on the current command value and the output current. The command value is generated, and the switching control signal Sic is output based on the voltage command value. As a result, the controller 230 varies the set speed (set frequency) according to the detected temperature Td, thereby changing the switching control signal Sic, which eventually leads to a change in the operating frequency of the electric motor 250.

4 is a block diagram of a motor control apparatus of an air conditioner according to an embodiment of the present invention.

Referring to the drawings, the motor control apparatus 400 of the air conditioner according to an embodiment of the present invention, the converter 410, the inverter 420, the control unit 430, and the input current detection unit (A) Include. Motor control apparatus 400 of the air conditioner according to an embodiment of the present invention may further include a reactor (L) and a smoothing capacitor (C).

The motor control apparatus 400 of the air conditioner of FIG. 4 is similar to the motor control apparatus 200 of the air conditioner of FIG. 2. Hereinafter, descriptions of the reactor L, the smoothing capacitor C, the converter 410, and the inverter 420 will be omitted.

The input current detector A detects an input current i _i flowing from the commercial AC power supply toward the converter. The input current detector A may be located between the three-phase AC power source and the reactor L, but is not limited thereto. The input current detector A may also be located between the reactor L and the converter 410. The input current detector A may include a current sensor, a current trnasformer (CT), a shunt resistor, or the like for detecting the input current.

The controller 430 controls the inverter 420. To this end, the controller 430 may generate and output an inverter switching control signal Sic based on the output current output from the inverter 420.

In addition, the controller 430 may control the driving frequency of the motor to vary according to the input current i _i detected by the input current detector A, which will be described later.

The detected input current i _i and the operation frequency variation of the motor will be described later with reference to FIG. 5.

5 is a diagram showing a relationship between an input current and an operating frequency of a motor according to the present invention.

Referring to the drawings, when the detected input current i _i is less than the first input current I1, the controller 430 controls the motor to be driven at a set frequency. The set frequency value may be determined by the controller 430. According to the determined set frequency, the controller 430 generates an inverter switching control signal Sic and controls the inverter 4200 accordingly. The set frequency may vary depending on whether the motor is started or whether the calculated load amount varies.

Next, when the detected input current i _i is between the second input current I2 and the first input current I1 larger than the first input current I1, the control unit 430 controls the motor 450. Control so that the actual operating frequency does not follow the set frequency. That is, it stops the rise or fall of the actual operating frequency of the motor 450, and controls to operate at a constant operating frequency. That is, the frequency between the first input current (I1) and the second input current (I2) is set as a frequency retention interval, so as to prevent the phenomenon that the operating frequency continues to fall when the operating frequency falls as in the prior art.

Next, when the detected input current i _i is between the third input current I3 and the second input current I2 larger than the second input current I2, the control unit 430 once, the motor 450. Control the actual operating frequency to decrease. For example, it is controlled to operate by lowering 5Hz from the actual operating frequency. This is to prevent the circuit burnout of the motor controller as the input current i _i rises.

Next, when the detected input current i _i is equal to or greater than the third input current I3, which is a threshold value, the controller 430 controls the motor 450 to stop. To this end, the controller 430 stops applying the inverter switching control signal Sic applied to the inverter 420. By this protection operation, it is possible to protect the motor control apparatus such as the inverter 420 including the plurality of switching elements.

Controller 430, and outputs by varying the switching control signal (Sic) in accordance with the detected input current so as to vary the operating frequency of the motor (i _i) in accordance with the detected input current (i _i) as shown in FIG.

The controller 430 estimates the speed of the motor 450 based on the output current of the inverter 420, generates a current command value based on the estimated speed and the set speed (set frequency), and generates a current command value and output current. Based on the voltage command value, a voltage command value is generated, and a switching control signal Sic is output. As a result, the controller 430 varies the set speed (set frequency) according to the detected input current i _i to change the switching control signal Sic, which in turn leads to a change in the operating frequency of the motor 450. .

On the other hand, in the embodiment of the present invention is described as varying the operating frequency of the motor 450 in accordance with the detected input current (i _i ), but is not limited to this, in accordance with the dc terminal current in the motor control device or output It is also possible to vary the operating frequency of the motor in accordance with the current.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical configuration of the present invention described above may be modified in other specific forms by those skilled in the art to which the present invention pertains without changing its technical spirit or essential features. It will be appreciated that it may be practiced. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is represented by the claims to be described later rather than the detailed description. Also, it is to be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention.

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

2 is a block diagram of a motor control apparatus of an air conditioner according to an embodiment of the present invention.

3 is a diagram showing the relationship between the temperature around the motor and the operating frequency of the motor according to the present invention.

4 is a block diagram of a motor control apparatus of an air conditioner according to an embodiment of the present invention.

5 is a diagram showing a relationship between an input current and an operating frequency of a motor according to the present invention.

<Explanation of symbols on main parts of the drawings>

L: reactor 210, 410: converter

220,420: inverter 230,430: control unit

240: temperature detection unit

Claims (9)

A converter for converting commercial AC power into DC power; An inverter having a plurality of switching elements and receiving the DC power and converting the AC power into an AC power by a switching operation of the switching element and supplying the same to an electric motor; A temperature detector detecting a temperature around the motor; And When the detected temperature is less than the first temperature, the motor is controlled to be driven at a set frequency, and when the detected temperature is between a second temperature greater than the first temperature and the first temperature, an operating frequency of the motor Control unit for controlling to stop the rising or falling of the air conditioner motor control apparatus comprising a. The method of claim 1, The control unit, if the detected temperature is between the third temperature and the second temperature greater than the second temperature, the motor control apparatus of the air conditioner, characterized in that for controlling the operation frequency of the electric motor to fall a predetermined value . The method of claim 2, And the control unit controls to stop the electric motor when the detected temperature is greater than the third temperature. The method of claim 1, wherein the temperature detector, And an inverter temperature detector for detecting a temperature of the switching element of the inverter. The method of claim 1, wherein the temperature detector, And a heat sink temperature detector that detects a temperature of the heat sink attached to the inverter. The method of claim 1, wherein the temperature detector, And a refrigerant discharge temperature detector for detecting a refrigerant discharge temperature of the compressor compressing the refrigerant according to the operation of the motor. A converter for converting commercial AC power into DC power; An inverter having a plurality of switching elements and receiving the DC power and converting the AC power into an AC power by a switching operation of the switching element and supplying the same to an electric motor; An input current detector for detecting an input current from the commercial AC power supply; And When the detected input current is less than the first current, the motor is controlled to be driven at a set frequency, and when the detected input current is between the second current greater than the first current and the first current, And a control unit controlling to stop the rising or falling of the operating frequency. The method of claim 7, wherein The control unit controls the motor of the air conditioner when the detected input current is between the third current greater than the second current and the second current so that the operating frequency of the motor falls a predetermined value. Device. The method of claim 8, And the control unit controls to stop the motor when the detected input current is greater than the third current.

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