KR100926162B1 - Motor controller of air conditionerand method of controlling motor - Google Patents

Abstract

According to the present invention, a three-phase alternating current of a predetermined frequency is applied to a motor based on a start operation section for applying a constant current to the motor during initial operation, and an output current flowing through the motor after the initial start operation. The present invention relates to a motor control method and an apparatus for controlling an air conditioner for controlling driving to be divided into a normal driving section, and controlling a gain in a microcomputer to be different from a starting driving section and a normal driving section. As a result, the response speed at the time of controlling the motor of the air conditioner and the control device of the air conditioner can be appropriately changed to stably control the motor.

Electric motor, initial start, normal operation, gain, microcomputer

Description

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

The present invention relates to a motor control method and an apparatus for controlling the air conditioner, and to an electric motor control apparatus and a control method for the air conditioner capable of stable control.

Conventional electric motor control devices, including the electric motor control device of the air conditioner, are controlled to drive the motor by converting the DC power into AC power using a commercial AC power, and converting the DC power into AC power having a predetermined voltage using an inverter. .

Conventionally, in order to control the operation of the motor, a sensor is attached to the inside or outside of the motor, thereby detecting the position of the rotor of the motor, and controlling the on / off of the switching element of the inverter based on this to follow the target speed command value. There was a sensor type control method.

On the other hand, in order to reduce the cost of a sensor or the like, a method of estimating the position of the rotor or the like based on the detected current by a sensorless method rather than a sensor method is also used.

The sensor type, sensorless method, and the like described above are controlled to follow the speed command value (target operation frequency). On the other hand, there are various discussions on the rapid increase of the motor speed at the time of motor abnormality, the rapid protection operation or the motor start in the sensorless method.

SUMMARY OF THE INVENTION An object of the present invention is to provide a motor control method and an apparatus for controlling an air conditioner capable of stably controlling the response speed during control by varying the gain during initial startup and normal operation. .

The motor control method of the air conditioner according to the embodiment of the present invention for solving the above-described problems and other problems, the start operation section for applying a constant current to the motor during the initial operation, and after the initial start operation, Based on the detected output current, the output current is detected and controlled to be divided into a normal operation section for applying a three-phase AC current of a predetermined frequency to the motor, and the gain in the microcomputer is controlled to be different from the start operation section and the normal operation section. do.

On the other hand, the motor control apparatus according to an embodiment of the present invention is provided with a plurality of switching elements, the inverter for converting the DC power supply to AC power supply to the motor, and the output current detection means for detecting the output current flowing to the motor; Outputs a start switching control signal for supplying a constant current to the motor in the start operation section; and a normal switching control signal for supplying a three-phase AC current of a predetermined frequency to the motor based on the detected output current in the normal operation section. It includes a microcomputer for outputting and setting the gains in the starting operation section and the normal operation section to be different from each other.

As described above, the motor control method and the control apparatus of the air conditioner according to the embodiment of the present invention, by varying the gain during the initial start and normal operation, the speed of response at the time of control is changed, and thus the motor It can be controlled stably.

In addition, it is possible to stably protect the motor in the event of a position detection failure.

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. 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.

2 is a circuit diagram illustrating a motor control apparatus of an air conditioner according to an embodiment of the present invention, and FIG. 3 is a timing diagram of an output current flowing to the motor.

2 to 3, the motor control apparatus 200 of the air conditioner according to an embodiment of the present invention, the converter 210, the inverter 220, the microcomputer 230, the output current detection means (E) may be included. In addition, the motor control apparatus 200 of the air conditioner may include a reactor 205, a smoothing capacitor C, a dc end voltage detection means D, and the like.

The reactor 205 boosts the commercial AC power and supplies it to the converter 210. Commercial AC power supplies can be either single phase or three phase, and are shown as single phase AC power in the drawings. The reactor 205 stores the AC power by the on / off operation of the switching element in the converter 210 and supplies it to the converter 210 to perform the boost operation. Reactor 205 is also used for power factor correction of AC power and for limiting harmonic currents between commercial AC power and converter 210.

 The converter 210 converts commercial AC power into DC power. The converter 210 includes a plurality of switching elements and a plurality of converter switching elements, and converts commercial AC power passed through the reactor 205 into DC power by on / off operation of the switching elements. When the commercial AC power source is a three-phase AC power source as shown in the drawing, the converter 210 is a pair of upper arm switching element and lower arm switching element connected in series with each other, and 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 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 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 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 signals Si and Sc from the microcomputer 230 are 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 220 is applied to each phase of the three-phase electric 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. On the other hand, if the three-phase electric motor 250 is classified by function, it may be a compressor electric motor (2b) used in the compressor of the air conditioner, it may be a fan motor (5b, 9b) for driving the fan.

The output current detecting means E detects the output current i _o of the inverter output stage, that is, the current applied to the motor 250. The output current detecting means E may be located between the inverter 220 and the motor 250, 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 E may be a shunt resistor, one end of which is connected to three lower arm switching elements of the inverter, unlike the drawing. The detected output current i _o is applied to the microcomputer 230.

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 detected dc terminal voltage Vdc is used to generate the converter switching control signal Scc.

In addition, the motor control apparatus 200 of the air conditioner according to an embodiment of the present invention is the input current detection means for detecting the input current from the commercial AC power supply and the input voltage detection for detecting the input voltage from the commercial AC power supply Means may further comprise.

The microcomputer 230 controls the switching operation of the inverter 220. Specifically, the microcomputer 230 controls the motor to be divided into a start operation section T1 which is an initial operation section of the motor and a normal operation section T3 after the initial start operation.

The start operation section T1 is a section for applying a constant current to the motor 250. For this purpose, any one of three phase arm switching elements of the inverter 220 is turned on, and the phase arm switching element is turned on. The remaining two unarmed haarm switching elements are turned on. The magnitude of the constant current may be a number A. In order to supply this constant current to the motor, the microcomputer 230 applies a start switching control signal Si to the inverter 220.

The normal operation section T3 is a section for applying an AC power source having a predetermined frequency to the motor 250 based on the output current i _o . For this purpose, the switching elements of the inverter 220 are transferred from the microcomputer 230. The on / off switching operation is performed by the normal switching control signal Sc.

The microcomputer 230 sets different gains in the start operation section T1 and the normal operation section T2. The start operation section T1 is a section for aligning the position of the motor rotor while starting the motor 250, and setting the gain to be smaller than the gain of the normal operation section T3 so as to quickly reach the target speed command value. desirable. In addition, since the start operation section T1 is a section for supplying a constant current, the gain may be constant.

On the other hand, the normal operation period (T3), the target speed command value (v ^*) as in the interval, is applied to a normal switch control signal of the PWM type driving so as to follow a target speed command value (v ^*) in accordance with or the speed of the actual motor It is also possible to vary the gain depending on the value. As a result, fast and precise control is possible.

When the actual motor speed reaches a predetermined value close to the target speed command value v ^* , the microcomputer 230 switches the start operation section T1 to the normal operation section T3 to drive the microcomputer 230. That is, it outputs the start-up switching control signal (Si) based on the target speed command value (v ^*), and outputs a target speed command value (v ^*) and the output current (i _o) normal switch control signal (Sc) based on.

Meanwhile, a forced acceleration section T2 for forcibly increasing the speed of the motor may be further located between the initial startup section T1 and the normal operation section T3. The microcomputer 230 may output the acceleration switching control signal Sf to the inverter 220 during the forced acceleration section T2.

 The gains described above may be PI gains as gains inside the microcomputer 220. Description of components and gains in the microcomputer 220 will be described later with reference to FIGS. 5 to 6.

Meanwhile, when the difference between the motor speed v and the target speed command value v ^* is greater than or equal to a predetermined value in the normal operation section T1, the microcomputer 220 determines that the initial startup failure is to stop the motor 250. You can also control it. That is, if the actual motor speed does not follow the target speed command value v ^* due to the initial rotor alignment failure, the inverter normally switches the control signal Sc to turn off all the switching elements of the inverter to stop the motor 250. Output to 220.

 Meanwhile, the converter 210 of FIG. 2 may be controlled together by the microcomputer 230, but is not limited thereto and may be controlled by a separate microcomputer.

4 is a simplified block diagram of the microcomputer of FIG. 2.

Referring to the drawings, the microcomputer 230 includes an estimator 405, a current command generator 410, a voltage command generator 420, and a switching control signal output unit 430.

The estimator 405 estimates the rotor speed v of the electric motor based on the output current i _o detected from the output current detecting means E.

The current command generation unit 410 generates the current command values i ^* _d and i ^* _q based on the estimated speed v and the speed command value v ^* . The current command generator 410 will be described later with reference to FIG. 5.

Voltage command generation unit 420 based on the current command value ^{_{(i * d, i * q}} ) and the detected current (i _o), generates a voltage command value ^{_{(v * d, v * q}} ). The voltage command generator 420 will be described later with reference to FIG. 5.

The switching control signal output unit 430 outputs the switching control signals Si and Sc to the inverter switching element based on the generated voltage command values v ^* _d and v ^* _q . In the start operation section T1, the start switching control signal Si is output, and in the normal operation section T3, the normal switching control signal Sc is output. On the other hand, when there is a forced acceleration section T2 between the start operation section T1 and the normal operation section T3, the switching control signal output unit 430 may accelerate the control switching signal Sf to the forced acceleration section T2. Also output.

5 is an internal block diagram of the current command generation unit of FIG. 4. 5A and 5B show a current command generation unit in the start operation section and the normal operation section, respectively.

Referring to the drawings, the current command generator 410 includes a PI controller 510 and a current command limiter 520.

First, in the start-up operation section T1, the PI controller 510 receives the PI gains Kp1 and Ki1 only with the speed command value v ^* , except for the estimated speed v estimated by the output current i _o . Multiply PI control to generate the current setpoint (i ^* _d1 , i ^* _q1 ). The current command limiting unit 520 generates a level limited current command value i ^* _d , i ^* _q by limiting the level of the current command value i ^* _d1 , i ^* _q1 . The PI gains Kp1 and Ki1 are preferably smaller than the PI gains Kp2 and Ki2 in the normal operation section T3 to be described later (Kp1 <Kp2 and Ki1 <Ki2). Thereby, damping becomes small and it becomes possible to reach the speed command value v ^* more quickly. In other words, the response is improved.

In addition, the PI gains Kp1 and Ki1 may be constant during the start operation section T1.

Next, in the normal operation section T3, the PI controller 515 performs a PI control by multiplying the PI gains Kp2 and Ki2 by the error between the estimated speed v and the speed command value v ^* , and the current command value i ^* _d1. , i ^* _q1 ) The current command limiting unit 525 generates a level limited current command value i ^* _d , i ^* _q by limiting the level of the current command value i ^* _d1 , i ^* _q1 . The PI gains Kp2 and Ki2 are preferably larger than the PI gains Kp1 and Ki1 in the start-operation section T1. In addition, the PI gains Kp2 and Ki2 may vary according to the speed of the motor, that is, the estimated speed v. This enables precise control in accordance with the motor state.

6 is an internal block diagram of the voltage command generation unit of FIG. 4. 6A and 6B show a voltage command generation unit in a start operation section and a normal operation section, respectively.

Referring to the drawings, the voltage command generator 420 includes a PI controller 610 and a voltage command limiter 620.

First, in the start operation section T1, the PI controller 610 performs a PI control that multiplies the PI gains Kp3 and Ki3 with only the current command values i ^* _d and i ^* _q , except for the output current i _o . To generate a voltage command value (v ^* _d1 , v ^* _q1 ). The voltage command limiting unit 620 generates a level limited voltage command value v ^* _d , v ^* _q by limiting the level of the voltage command value v ^* _d1 , v ^* _q1 . The PI gains Kp3 and Ki3 are preferably smaller than the PI gains Kp4 and Ki4 in the normal operation section T3 described later. (Kp3 < Kp4 and Ki3 < Ki4) By this, the damping becomes small and the speed command value ( v ^* ) can be reached faster. In other words, the response is improved.

In addition, the PI gains Kp3 and Ki3 may be constant during the start operation section T1.

Next, in the normal operation section T3, the PI controller 615 performs PI control by multiplying the PI gains Kp4 and Ki4 by the error between the output current i _o and the current command value i ^* _d , i ^* _q . Generate a voltage setpoint (v ^* _d1 , v ^* _q1 ). The voltage command limiting unit 625 generates a level limited voltage command value v ^* _d , v ^* _q by limiting the level of the voltage command value v ^* _d1 , v ^* _q1 . The PI gains Kp4 and Ki4 are preferably larger than the PI gains Kp3 and Ki3 in the start-operation section T1. In addition, the PI gains Kp4 and Ki4 may vary according to the speed of the motor, that is, the estimated speed v. This enables precise control in accordance with the motor state.

On the other hand, unlike the figure, it is also possible to use the d, q-axis converted value of the output current (i _o ) instead of the output current (i _o ).

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

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

3 is a timing diagram of an output current flowing to the motor.

4 is a simplified block diagram of the microcomputer of FIG. 2.

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

6 is an internal block diagram of the voltage command generation unit of FIG. 4.

<Explanation of symbols on main parts of the drawings>

205: reactor 210: converter

220: inverter 230: microcomputer

405: Estimation 410: Current command generator

420: voltage command generator 430: switching control signal output unit

510,515,610,615: PI controller

Claims (20)

A method of controlling an electric motor of an air conditioner including an inverter for driving an electric motor and a microcomputer for outputting a switching control signal to the inverter, A start operation section for applying a constant current to the motor during initial operation; After the initial start-up operation, the output current flowing to the motor is detected and controlled to be divided into a normal operation section for applying a three-phase AC current of a predetermined frequency to the motor based on the detected output current. The gain in the microcomputer is controlled to be different from each other in the start operation section and the normal operation section, In the normal operation section, And if the difference between the detected motor speed and the target speed command value is greater than or equal to the predetermined value based on the output current, determine that the initial start fails and stop the motor. The method of claim 1, The gain of the start operation section is smaller than the gain of the normal operation section of the motor control method of the air conditioner. The method of claim 1, The gain of the start operation section is a motor control method of the air conditioner, characterized in that the constant. The method of claim 1, The gain of the normal operation section is a motor control method of the air conditioner, characterized in that the variable according to the motor speed. The method according to any one of claims 1 to 4, The gain of the microcomputer vibrator control method of the air conditioner, characterized in that the PI gain. The method of claim 1, The constant current is Any one of the three phase arm switching elements of the inverter is turned on, and the other two arm arm switching elements that do not correspond to the turned on arm switching element is turned on and supplied to the motor. . delete The method of claim 1, And a forced acceleration section for gradually increasing a speed of the motor between the start operation section and the normal operation section. An inverter having a plurality of switching elements, converting a direct current power source into an alternating current power source and supplying it to an electric motor; Output current detection means for detecting an output current flowing to the motor; And In the start operation section, a normal switching control outputting a start switching control signal for supplying a constant current to the motor, and in the normal operation section, supplying a three-phase AC current of a predetermined frequency to the motor based on the detected output current. And a microcomputer for outputting a signal and setting the gains in the start operation section and the normal operation section to be different from each other. The microcomputer In the normal operation section, when the difference between the motor speed detected based on the output current and the target speed command value is more than a predetermined value, it is determined that the initial start failure, the air conditioner characterized in that the control to stop the motor. Motor control device. The method of claim 9, The microcomputer And the gain of the start operation section is set to be smaller than the gain of the normal operation section. The method of claim 9, The microcomputer The motor control apparatus of the air conditioner, characterized in that the gain of the start operation section is set to be constant. The method of claim 9, The microcomputer The motor control apparatus of the air conditioner, characterized in that the gain of the normal operation section is set to vary according to the speed of the motor. The method according to any one of claims 9 to 12, The microcomputer, An estimator estimating a speed based on the output current; A current command generation unit that generates a current command value based on the estimated speed and the speed command value; A voltage command generator for generating a voltage command value based on the current command value and the output current; And And a switching control signal output unit for outputting the switching control signal based on the voltage command value. The method of claim 13, The current command generation unit includes a PI controller for generating a current command value based on the estimated speed and the speed command value, The gain of the microcomputer is a motor controller of an air conditioner, characterized in that the gain of the PI controller. The method of claim 13, The voltage command generation unit includes a PI controller that generates a voltage command value based on the current command value and the output current, The gain of the microcomputer is a motor controller of an air conditioner, characterized in that the gain of the PI controller. The method of claim 13, The microcomputer, And the start switching control signal is output based on the speed command value. The method of claim 13, The microcomputer, And the normal switching control signal is output based on the estimated speed and the speed command value. The method of claim 9, The constant current is Any one of the three phase arm switching elements of the inverter is turned on, and the other two arm arm switching elements that do not correspond to the turned on arm switching element is turned on and supplied to the motor. . delete The method of claim 9, The microcomputer, And an acceleration switching control signal for gradually increasing the speed of the motor in a forced acceleration section between the start operation section and the normal operation section.

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