KR100903646B1 - Motor controller of air conditioner - Google Patents

Abstract

The present invention includes a inverter having a plurality of switching elements, converted to commercial AC power of a predetermined frequency using a converted DC power supply, and supplied to a three-phase electric motor, output current detection means for detecting an output current of the inverter, and detection. A speed estimator for estimating the speed of the motor based on the output current, and a PI controller for performing a PI control after weighting an error between the speed estimate and the set speed command value according to a predetermined condition, and performing a PI control. A motor control apparatus for an air conditioner includes a current command generation unit and a switching control signal output unit for outputting a switching control signal to a switching element of an inverter based on the current command value. As a result, it is possible to adjust the PI control in the motor controller of the air conditioner to react more quickly to a large error.

Air Conditioner, Electric Motor, PI Control, Gain

Description

Motor controller of air conditioner {Motor controller of air conditioner}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor control apparatus of an air conditioner, and more particularly, to an electric motor control apparatus of an air conditioner that is adjustable to react more quickly to a large error in PI control in an electric motor control apparatus of an air conditioner.

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 the motor, such as a compressor, the motor control device for driving this is used. The motor controller of the air conditioner receives a commercial AC power source and converts it into a DC voltage, converts the DC voltage into a commercial AC power of a predetermined frequency, and supplies the motor to the motor to control the motor. The motor controller of an air conditioner normally uses a PI controller.

1 is a block diagram showing a PI controller used in a motor control apparatus of a conventional air conditioner.

Referring to the drawings, the conventional PI controller 100 generates the output value u by multiplying the PI gains Kp and Ki by the error e between the command value z ^* and the detected value z.

However, in the conventional PI controller 100, as the error e increases, the time for which the error e converges to 0 becomes long, and the time for which the output value u reaches a desired value becomes long, so that the control operation is stable. Cannot be performed.

To this end, a method of dividing sections according to the detected value z and applying PI gains Kp and Ki for each section to shorten the arrival time is used, but the PI gains Kp and Ki are changed. Discontinuous control is performed in the section, which leads to a problem of poor control stability.

It is an object of the present invention to provide an electric motor control device of an air conditioner that is adjustable to react more quickly to large errors in the PI control in the electric motor control device of the air conditioner.

In addition, another object of the present invention, in the electric motor control device of the air conditioner, by using a converter provided with a switching element, power factor control and DC voltage boosting is possible, it is possible to cope with harmonic regulation.

The motor control apparatus of the air conditioner according to the embodiment of the present invention for solving the above-described problems and other problems, is provided with a plurality of switching elements, and converted to a commercial AC power source of a predetermined frequency using the converted DC power source The inverter supplied to the three-phase motor, the output current detecting means for detecting the output current of the inverter, the speed estimating unit for estimating the speed of the motor based on the detected output current, the error between the speed estimation value and the set speed command value. A current command generation unit including a PI controller which performs a PI control after weighting according to a predetermined condition, and a switching control signal output unit outputting a switching control signal to a switching element of the inverter based on the current command value Include.

On the other hand, the electric motor control apparatus of the air conditioner according to an embodiment of the present invention, a converter having a plurality of switching elements, supplied with commercial AC power to perform a DC power conversion by the switching operation of the switching element, and the converter A dc voltage detection means for detecting a dc voltage as an output terminal, and a current command generation unit generating a current command value by performing PI control after weighting an error between the dc end voltage detection value and the set dc end voltage command value according to a predetermined condition. And a switching control signal output section for outputting a switching control signal to the switching element based on the current command value.

As described above, the motor control apparatus of the air conditioner according to the embodiment of the present invention can be adjusted to react more quickly to a large error during PI control in the motor control apparatus of the air conditioner.

In addition, the motor control apparatus of the air conditioner according to the embodiment of the present invention, by using a converter provided with a switching element, power factor control and DC voltage boosting is possible, it can cope with harmonic regulation (harmonic).

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

2 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 fan 5 disposed on one side of the heat exchanger 5 and configured to include an outdoor fan 5a for promoting heat dissipation of the refrigerant and an electric fan 5b for rotating the outdoor fan 5a, and an expansion for expanding the condensed refrigerant; The mechanism 6, the cooling / heating switching valve 10 for changing the flow path of the compressed refrigerant, and the accumulator 3 for temporarily storing the gasified refrigerant to remove moisture and foreign matter 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.

3 is a circuit diagram illustrating a motor control apparatus of an air conditioner according to an embodiment of the present invention.

Referring to the drawings, the motor control apparatus 300 of the air conditioner according to an embodiment of the present invention, the reactor 305, converter 310, smoothing capacitor (C11), inverter 320, converter microcomputer 340, the inverter microcomputer 330, and the like. In addition, the motor control apparatus 300 of the air conditioner may include a dc end voltage detection means (D), an output current detection means (E or F), and the like.

The reactor 305 boosts the commercial AC power and supplies it to the converter 310. Specifically, the AC power is stored in the reactor 305 and supplied to the converter 310 by the on / off operation of the plurality of converter switches provided in the converter 310, thereby performing a boosting operation. On the other hand, the reactor 305 is used for power factor correction of the AC power, and serves to protect the system or converter element by removing the harmonic current between the commercial AC power supply and the converter 310.

On the other hand, it is also possible to use a common mode LCL filter (not shown) instead of the reactor 305 for step-up operation, power factor correction and removal of harmonic currents. When the commercial AC power source is a three-phase AC power source, the magnitude of the harmonic current generated by the high speed switching of the converter may be increased, and in order to effectively limit this, a common mode LCL filter may be used.

 The converter 310 includes a plurality of converter switching elements, and converts commercial AC power passed through the reactor 305 into DC power by on / off operation of the switching device. 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. Each switching device has a diode in anti-parallel connection. When the switching control signal Scc from the converter micom 340 is input to the gate terminal of each switching element, each switching element performs a switching operation. Power factor is controlled by this, and commercial AC power is converted into DC power and output.

The smoothing capacitor C11 is connected to the output terminal of the converter 310. The converted DC power output from the converter 310 is smoothed. Hereinafter, the output terminal of the converter 310 is called a dc terminal or a dc link terminal. The DC voltage smoothed at the dc stage is applied to the inverter 320.

The inverter 320 includes a plurality of inverter switching elements, and converts the DC power smoothed by the on / off operation of the switching element into commercial AC power 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. Each switching device has a diode in anti-parallel connection. When the switching control signal Sic from the inverter micom 330 is input to the gate terminal of each switching element, each switching element performs a switching operation. As a result, a three-phase AC power supply having a predetermined frequency is output.

Three-phase AC power output from the inverter 320 is applied to each phase of the three-phase electric motor 350. Here, the three-phase electric motor 350 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 350 may be of various forms, such as a BLDC motor, a synRM motor. On the other hand, if the three-phase electric motor 350 is classified by function, it may be a compressor motor (2b) used in the compressor of the air conditioner, it may be a fan motor (5b, 9b) for driving the fan.

On the other hand, the converter microcomputer 340 outputs the converter switching control signal Scc to the converter 310 in order to control the switching operation of the converter. The switching control signal Scc is a PWM switching control signal, which is generated based on the detected dc terminal voltage and output to the converter 310. The description of the converter micom 340 will be described later with reference to FIGS. 6 to 7.

On the other hand, the inverter microcomputer 330 outputs the inverter switching control signal Sic to the inverter 320 in order to control the switching operation of the inverter. The switching control signal Sic is a PWM switching control signal and is generated based on the detected output current and output to the inverter 330. A detailed description of the inverter micom will be described later with reference to FIGS. 4 to 5.

As in the embodiment of the present invention, according to the motor control apparatus of the air conditioner for operating the converter and the inverter using a commercial AC power source, the converter 310 and the reactor 305 including the switching element for the converter are mutually In conjunction, AC power up, power factor control and harmonic limiting are performed.

The dc end voltage detection means D detects the dc end voltage Vdc. As the dc stage voltage detecting means D, a resistor or the like may be used between both ends of the dc stage. The dc stage voltage detection unit D may detect a dc stage voltage Vdc on an average, and the detected dc stage voltage Vdc may be applied to the converter micom 340.

The output current detecting means E or F detects the output current i _o of the inverter output stage, that is, the current applied to the motor. The output current detecting means E may be located between the inverter 320 and the motor 350, and a current sensor, a current trnasformer (CT), a shunt resistor, or the like may be used to detect the current. The output current detecting means F may be a shunt resistor having one end connected to each of the three lower arm switching elements of the inverter.

4 is a simplified block diagram of the inverter microcomputer, and FIG. 5 is an internal block diagram of the current command generation unit.

4 to 5, the inverter microcomputer 330 includes a speed estimating unit 405 for estimating the rotor speed v of the motor based on the detected output current i _o , and an estimated speed ( v) and a current command generator 410 for generating a current command value i ^* _d , i ^* _q based on the command speed v * and the current command value i ^* _d , i ^* _q and the detected current ( the voltage command generator 420 for generating a voltage command value v ^* _d , v ^* _q based on i _o ) and a switching element for an inverter based on the generated voltage command value v ^* _d , v ^* _q . It includes a switching control signal output unit 430 for outputting a switching control signal (Sic).

The current command generator 410 includes a PI controller 510 and a current command limiter 520. The PI controller 510 weights the error e when the error e between the estimated speed v and the command speed v * is greater than a predetermined value, and multiplies the error weight by the PI gains Kp and Ki. PI control is performed to generate current commands (i ^* _d1 , i ^* _q1 ). The weight of the error may be the square of the error (e ² ). If the weight of the squared error (e ²⁾ of the error, the error is weighted sign (+ or -) of the error it may be a value obtained by multiplying the square (e ²⁾ of the error. In addition, the weight of the error may be a proportional constant. On the other hand, when the error is less than or equal to the predetermined value, PI control is performed on the error e without weighting. If the error is less than a predetermined value, fine PI control can be performed. If the error is greater than the predetermined value, the response speed is increased by amplifying the error. Therefore, the desired target value can be obtained as soon as possible.

The current command limiting unit 520 limits the level of the current command i ^* _d1 , i ^* _q1 generated by the PI controller 510 to finally generate the current command i ^* _d , i ^* _q .

Meanwhile, similar to the current command generator 410, the voltage command generator 420 of FIG. 4 may include a PI controller and a voltage command limiter.

FIG. 6 is a simplified block diagram of the converter microcomputer, and FIG. 7 is a block diagram of the current command generation unit of FIG. 6.

Referring to FIG. 6 to FIG. 7, the converter micom 340 is based on the detected dc terminal voltage Vdc and the dc voltage command value V ^* dc, and d and q-axis current command values i ^* _d and i. ^* _q) the current command generating unit 610 to generate a, d, q-axis current command value _{^{(i * d, i * q}} ) and based on the input current (i _i to be detected), d, q-axis voltage command value (v switching control signal Scc to drive the switching element for the converter based on the voltage command generation unit 620 for generating ^* _d , v ^* _q ) and d, q-axis voltage command values v ^* _d , v ^* _q . It includes a switching control signal output unit 630 for outputting.

The current command generator 610 includes a PI controller 710 and a current command limiter 720. The PI controller 710 weights the error e when the detected error of the dc terminal voltage Vdc and the dc voltage command value V ^* dc is greater than a predetermined value, and the PI gain Kp to the error weight. The PI control is multiplied by, Ki to generate a current command (i ^* _d1 , i ^* _q1 ). The weight of the error may be the square of the error (e ² ). When the weight of the error is the square of the error (e ² ), the weight of the error may be a value obtained by multiplying the sign of the error (+ or-) by the square of the error (e ² ). In addition, the weight of the error may be a proportional constant. On the other hand, when the error is less than or equal to the predetermined value, PI control is performed on the error e without weighting. If the error is less than a predetermined value, fine PI control can be performed. If the error is greater than the predetermined value, the response speed is increased by amplifying the error. Therefore, the desired target value can be obtained as soon as possible.

The current command limiter 720 restricts the level of the current command i ^* _d1 , i ^* _q1 generated by the PI controller 710 to finally generate the current command i ^* _d , i ^* _q .

Meanwhile, similar to the current command generator 610, the voltage command generator 620 of FIG. 6 may include a PI controller and a voltage command limiter.

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 shown by the claims below, rather than the above 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 block diagram showing a PI controller used in a motor control apparatus of a conventional air conditioner.

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

3 is a circuit diagram illustrating a motor control apparatus of an air conditioner according to an embodiment of the present invention.

4 is a simplified block diagram of an inverter microcomputer.

5 is an internal block diagram of the current command generation unit of FIG. 4.

6 is a simplified block diagram of the converter microcomputer.

FIG. 7 is an internal block diagram of the current command generation unit of FIG. 6.

<Explanation of symbols on main parts of the drawings>

305: reactor 310: converter

320: inverter 330: inverter microcomputer

340: converter microcomputer 410,610: current command generator

420,620: Voltage command generator 510,710: PI controller

520,720: Current command limit unit

Claims (16)

In the motor control device of the air conditioner, An inverter having a plurality of switching elements, the inverter converts the commercial AC power of a predetermined frequency into a three-phase electric motor by using the converted DC power; Output current detecting means for detecting an output current of the inverter; A speed estimating unit estimating a speed of the electric motor based on the detected output current; A current command generation unit including a PI controller configured to generate a current command value by performing a PI control after weighting according to an error between the speed estimate value and the set speed command value; And A switching control signal output unit outputting a switching control signal to a switching element of the inverter based on the current command value; Electric motor control device of the air conditioner, comprising a. The method of claim 1, And the current command generation unit adds the weight to the speed error when the speed error is greater than a predetermined value. The method of claim 1, Wherein the weight is a square of the speed error. The method of claim 1, And the current command generator further includes a current command limiter configured to limit the level of the current command value. The method of claim 1, And a voltage command generation unit including a second PI controller which generates a voltage command value by performing a PI control after assigning a second weight value according to a current error between the current command value and the detected current command value. Motor controller of an air conditioner. The method of claim 5, And the voltage command generation unit adds the second weight to the voltage error when the current error is greater than a predetermined value. The method of claim 5, And the second weight is a square of the voltage error. The method of claim 5, The voltage command generation unit further includes a voltage command limiting unit limiting the level of the voltage command value. In the motor control device of the air conditioner, A converter having a plurality of switching elements and receiving commercial AC power to perform DC power conversion by the switching operation of the switching elements; Dc voltage detecting means for detecting a dc voltage which is an output terminal of the converter; A current command generation unit configured to generate a current command value by performing PI control after assigning a weight according to an error between the dc end voltage detection value and the set dc end voltage command value; and A switching control signal output unit outputting a switching control signal to the switching element based on the current command value; Electric motor control device of the air conditioner, comprising a. The method of claim 9, And the current command generation unit adds the weight to the dc end voltage error when the dc end voltage error is greater than a predetermined value. The method of claim 9, And the weight is a square of the dc terminal voltage error. The method of claim 9, And the current command generator further includes a current command limiter configured to limit the level of the current command value. The method of claim 9, And a voltage command generation unit including a second PI controller which generates a voltage command value by performing a PI control after assigning a second weight value according to a current error between the current command value and the detected current command value. Motor controller of an air conditioner. The method of claim 13, And the voltage command generation unit adds the second weight to the voltage error when the current error is greater than a predetermined value. The method of claim 13, And the second weight is a square of the voltage error. The method of claim 13, The voltage command generation unit further includes a voltage command limiting unit limiting the level of the voltage command value.

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