KR101049930B1 - Electric motor drive of air conditioner - Google Patents

Abstract

The present invention is provided with a switching element, a converter for converting an input AC power source to a DC power source by a switching operation, an input current detector for detecting an input current from the input AC power source, and a plurality of switching elements. In operation, the inverter converts the DC power into an AC power of a predetermined frequency to drive the motor, and determines the duty of the switching element of the converter based on the detected input current, and drives the switching element of the converter according to the determined duty. It relates to an electric motor driving apparatus of an air conditioner including a control unit for outputting a converter switching control signal. This makes it possible to simply calculate the duty of the converter switching element of the motor drive device.

Motor, drive, input current, detection, duty

Description

Apparatus for dirving motor of air conditioner

The present invention relates to an electric motor driving apparatus of an air conditioner, and more particularly, to an electric motor driving apparatus of an air conditioner capable of simply calculating the duty of the converter switching element of the electric motor driving apparatus.

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. On the side, an outdoor unit that performs heat dissipation and compression functions was installed, and two separate devices were connected by refrigerant pipes.

In the air conditioner, an electric motor is used for a compressor, a fan, and the like, and an electric motor driving device for driving the air conditioner is used. The motor driving device receives a commercial AC power, converts the DC voltage into a DC voltage, converts the DC voltage into a commercial AC power having a predetermined frequency, and supplies the same to the motor, thereby controlling the motor to drive a motor such as a compressor or a fan.

On the other hand, as the requirements for high performance and high efficiency of air conditioners increase, problems such as harmonic current, input power factor, EMC, and the like have been raised.

For example, if harmonic current inflow and input power factor characteristics to the input power supply side become poor, it may adversely affect the malfunction and lifetime of other electric devices connected to the power system. Accordingly, countries are implementing or promoting regulations to improve power quality. In particular, the EU has implemented regulations such as IEC6100-3-2, which is the harmonic current regulation. Accordingly, various efforts have been made to improve the harmonic noise as well as to develop a motor driving apparatus of an air conditioner for reducing the manufacturing cost accordingly.

An object of the present invention is to provide an electric motor drive device of an air conditioner that can easily calculate the duty of a converter switching element of the electric motor drive device.

An electric motor drive apparatus for an air conditioner according to an embodiment of the present invention for solving the above-described problems and other problems includes a switching element, a converter for converting an input AC power source into a DC power source by a switching operation, and an input. An input current detection unit for detecting an input current from an AC power supply, a plurality of switching elements, an inverter for converting a DC power source into an AC power source having a predetermined frequency to drive the motor by a switching operation, and based on the detected input current And a controller for determining a duty of the switching element of the converter and outputting a converter switching control signal for driving the switching element of the converter according to the determined duty.

As described above, the motor driving apparatus of the air conditioner according to the embodiment of the present invention can simply calculate the duty of the converter switching element of the motor driving apparatus based on the detected input current. In addition, the input power factor can be stably secured in spite of the load variation during the operation of the motor.

On the other hand, the input voltage in the motor drive device can be estimated simply and accurately based on the detected input current. In addition, it is possible to accurately determine whether the overvoltage is based on the detected magnitude of the input voltage. Accordingly, it is possible to ensure the safety of the circuit elements in the driving device when determining the overvoltage.

In addition, by using the LCL filter in front of the converter, it is possible to efficiently remove the input current ripple component caused by the switching operation of the switching element.

In addition, since the control unit simultaneously controls the converter and the inverter, when the magnitude of the input voltage is overvoltage, the operation of the inverter as well as the converter is stopped, thereby further securing the stability of the circuit elements in the driving apparatus.

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 4 and including an outdoor fan 5a for promoting heat dissipation of the refrigerant and an electric motor 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 in the room to perform a cooling / heating function of the indoor side heat exchanger (8), and the indoor fan (9a) and the room disposed on one side of the indoor side 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 motor in the motor drive device of the air conditioner according to an embodiment of the present invention can be each of the motor (2b, 5b, 9b) to operate the outdoor fan, compressor or indoor fan of the air conditioner, shown in the figure have.

Meanwhile, although FIG. 1 illustrates one indoor unit (I) and one outdoor unit (O), the driving device of the air conditioner according to the embodiment of the present invention is not limited thereto, and includes a plurality of indoor units and outdoor units. Applicable to the air conditioner, an air conditioner having a single indoor unit and a plurality of outdoor units, of course.

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

Referring to the drawings, the motor driving apparatus 200 of FIG. 2 according to an embodiment of the present invention includes a converter 210, an inverter 220, a controller 230, and an input current detector A. In addition, the motor driving apparatus 200 of FIG. 2 may further include reactors L1 and L2, a smoothing capacitor C, a dc terminal voltage detector B, an output current detector E, and the like.

A reactor (L1, L2) is disposed between the commercial AC power source (205, v _s) and the converter 210, and performs power factor correction or a step-up operation. In addition, the reactors L1 and L2 may perform a function of limiting harmonic currents caused by the fast switching of the converter 210.

The input current detector A may detect an input current i _s input from the commercial AC power supply 205. To this end, a current sensor, a CT (current trnasformer), a shunt resistor, or the like may be used as the input current detector A. The detected input current i _s is a discrete signal in the form of a pulse and may be input to the controller 230 for generation of the converter switching control signal Scc and estimation of the input voltage v _s .

The converter 210 converts the commercial AC power source 205 through the reactors L1 and L2 into a DC power source and outputs the DC power source. Although the commercial AC power supply 205 is shown as a single phase AC power supply in the figure, it may be a three phase AC power supply. The internal structure of the converter 210 also varies according to the type of the commercial AC power source 205. 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 switching element and performs a boosting operation, a power factor improvement, and a DC power conversion by a switching operation. On the other hand, the converter 210 may be made of a diode or the like to perform rectification without a separate 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 dc end voltage detector B may detect a dc end voltage Vdc that is both ends of the smoothing capacitor C. To this end, the dc terminal voltage detector B may include a resistor, an amplifier, and the like. The detected dc terminal voltage Vdc is a discrete signal in the form of a pulse and may be input to the controller 230 to generate the converter switching control signal Scc.

The inverter 220 includes a plurality of inverter switching elements, converts a smoothed DC power source into a three-phase AC power source having a predetermined frequency by on / off operation of the switching element, and outputs the same to the three-phase electric motor 250.

Inverter 220 is a pair of upper arm switching elements (Sa, Sb, Sc) and lower arm switching elements (S'a, S'b, S'c) connected in series with each other, a total of three pairs of upper and lower arms The switching elements are connected in parallel with each other (Sa & S'a, Sb & S'b, Sc & S'c). Diodes are connected in anti-parallel to each of the switching elements Sa, S'a, Sb, S'b, Sc, and S'c.

The switching elements in the inverter 220 perform on / off operations of the respective switching elements based on the inverter switching control signal Sic from the controller 230. As a result, the three-phase AC power supply having the predetermined frequency is output to the three-phase electric motor 250.

The controller 230 controls the switching operation of the converter 210. To this end, the controller 230 receives an input current i _s detected by the input current detector A.

The controller 230 outputs a converter switching control signal Scc to the converter 210 to control the switching operation of the converter 210. The converter switching control signal Scc is a PWM switching control signal, which is generated and output based on the input current i _s detected from the input current detector A. A detailed operation of the output of the converter switching control signal Scc in the controller 230 will be described later with reference to FIG. 4.

In addition, the controller 230 estimates the magnitude and phase of the input voltage v _s based on the input current i _s detected by the input current detector A. FIG. The controller 230 may perform an overvoltage protection operation based on the estimated magnitude of the input voltage v _s . This will be described later with reference to FIG. 4.

In addition, the controller 230 may control the switching operation of the inverter 220. To this end, the controller 230 may receive an output current io detected by the output current detector E. FIG.

The controller 230 outputs an inverter switching control signal Sic to the inverter 220 in order to control the switching operation of the inverter 220. The inverter switching control signal Sic is a PWM switching control signal and is generated and output based on the output current value io detected by the output current detector E. FIG. Detailed operation of the output of the inverter switching control signal (Sic) in the control unit 230 will be described later with reference to FIG.

The output current detector E detects the output current io flowing between the inverter 220 and the three-phase motor 250. In other words, the current flowing through the motor 250 is detected. The output current detector E may detect the output current of each phase, or may detect the output current of one or two phases by using three-phase equilibrium.

The output current detector 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 for current detection. In addition, one end of the shunt resistor may be connected to three lower arm switching elements S'a, S'b, and S'c of the inverter 220, respectively.

The detected output current io may be applied to the controller 230 as a discrete signal in the form of a pulse, and an inverter switching control signal Sic is generated based on the detected output current io. .

Three-phase electric motor 250 is provided with a stator and a rotor, each phase AC power of a predetermined frequency is applied to the coil of each stator, the rotor is rotated. The type of the motor 250 may be a variety of forms, such as a brushless DC (BLDC) motor, a synchronous reluctance motor (synRM).

The three-phase electric motor 250 may be used as a fan motor or a compressor motor in an outdoor unit of an air conditioner, and may also be used as a fan motor in an indoor unit of an air conditioner.

On the other hand, when the driving device 200 of the air conditioner described above, for example, for driving a fan motor or a compressor motor used in the outdoor unit, the control unit 230 as an outdoor unit control unit, can be disposed separately in the indoor unit. It is also possible to perform further communication with the indoor unit controller. The outdoor unit control unit receives a driving command by communication with the indoor unit control unit, and can determine a speed command value to be described later based on the received driving command.

In addition, the controller 230 of the driving apparatus 200 of the air conditioner described above may control the fan motor and the compressor motor used in the outdoor unit at the same time.

3 is a circuit diagram illustrating an example of the converter of FIG. 2.

Referring to the drawings, the converter 210 includes four diode elements D1 to D4 and two switching elements S1 to S2. In addition, two resistance elements Rs may be further provided.

For rectifying operation of the converter 210, four diode elements D1 to D4 are arranged in a bridge form in a single-phase commercial AC power supply. That is, the first and second diode elements D1 to D2 are connected in series with each other, the third and fourth diode elements D3 to D4 are connected in series with each other, and the first and second diode elements D1 are connected to each other in series. It is connected in parallel with ~ D2). Among the lower two diode elements D2 and D4, the switching elements S1 to S2 are connected in parallel, respectively. In addition, two resistance elements Rs may be connected to one end of the two diode elements D2 and D4, respectively.

A brief description will be made of a current component stored in the reactors L1 and L2 by the turn-on operation of the switching element S1 or S2, and by the turn-off operation of the switching element S1 or S2. The current component stored in L2) is stored in the smoothing capacitor (C). Thereby, the boosting function is performed, and the power factor correction is performed by the on / off switching time.

4 is a simplified block diagram of the inside of the controller of FIG. 2.

Referring to the drawings, the controller 230 includes a current command generator 410, an input voltage estimator 415, and a duty to generate the converter switching control signal Scc and estimate the input voltage v _s . The generation unit 420, the abnormality determination unit 425, and the switching control signal output unit 430 are included.

The current command generator 410 generates a current command value I ^* based on the detected dc terminal voltage Vdc and the dc voltage command value V ^* dc. For example, the current command generator 410 may generate a current command value I ^* by performing PI control based on a difference between the detected dc terminal voltage Vdc and the dc voltage command value V ^* dc. Can be. To this end, the current command generation unit 410 may include a PI controller (not shown). In addition, a limiter (not shown) may be further provided to limit the level so that the current command value I ^* does not exceed the allowable range.

The input voltage estimator 415 estimates the magnitude V _M and the phase θ _M of the input voltage from the input current i _s detected from the input current detector A.

Hereinafter, the contents of estimating the input voltage from the detected input current, which is an embodiment of the present invention, will be described based on the converter 210 of FIG. 3. That is, by controlling the deviation Δi between the model input current i _M and the detected input current i _s by modeling the electrical equation of the converter 210 to zero, the amplitude V _M and the phase angle of the input voltage are zero. Estimate (θ _M ).

First, the commercial AC power supply v _s in the motor driving apparatus 200 of FIG. 2 is expressed by Equation 1 below.

Next, the voltage equation from the commercial AC power supply v _s to the smoothing capacitor C in the motor driving apparatus 200 of FIG. 2 is expressed by Equation 2 below.

Here, Vr is 0 V when the switching element S1 or S2 is turned on, and Vdc is a voltage across the smoothing capacitor C when the switching element S1 or S2 is turned off.

Therefore, the average voltage during one cycle of the commercial AC power supply (v _s ) is expressed by Equation 3 below.

Here, d represents the turn-on duty ratio of the switching element S1 or S2, the value of which is between 0 and 1.

Meanwhile, when Equation 2 is converted into a discrete equation for processing by the controller 230, Equation 4 below.

Here, Ts is a control period. This may be the same as the sampling period.

In addition, the input voltage v _s [n-1] is expressed by Equation 5 as a peak value V _s of the input voltage and a corresponding phase angle θ _s .

In addition, the phase angle θ _s [n] is expressed as shown in the following 6 as a value corresponding to the phase angle and the initial phase angle θ ₀ at the time point [n-1].

On the other hand, the above equation (4) is summarized as in the following equation (7).

On the other hand, the estimated input voltage is defined with the following equation (8).

Here, v _M is the estimated input voltage by modeling, V _M is the maximum value of the estimated input voltage, and θ _M represents the estimated phase angle.

Equation (7) is an ideal equation for the actual input current (i _s ), the electrical equation modeling the converter 210 can be changed to the following equation (9) can be expressed.

The reactance (L _M1 , L _M2 ) of the reactor modeled in Equation 9 and the resistance value R _M of the resistance element are respectively the actual values L1 and L2 of the reactor and the actual value Rs of the resistance element in FIG. 2. If it is assumed to be equal to, the current error Δi _s between the actual input current i _s and the modeled input current i _M is expressed by Equation 10 below.

In this case, the input voltage error Δv is represented by the following Equation 11 because an error exists in magnitude and phase, respectively.

When Equation 10 is rearranged using Equation 11, Equation 12 is expressed as follows.

If Equation 12 is arranged using a Fourier series, the input voltage error Δv and the phase error Δθ of the input voltage may be obtained as follows.

By substituting Equation 12 into Equations 13 and 14, the magnitude of the input voltage V _M and the phase θ _M can be estimated as follows.

In Equations 15 and 16, K _E is a current gain and K _θ is a current phase gain. K _E is obtained based on the inductances L1 and L2 of the reactor and the control period T _S , and K _θ is the magnitude of the input voltage as well as the inductance L1 and L2 and the control period T _S of the reactor. V _M ) is obtained based on the component.

In short, the size (V _M) of the input voltage is estimated based on the detected input current (i _s) and a current gain (K _E), the inductance of the current gain (K _E) is a reactor of the time (L1, L2 ) And the control period T _S.

Further, the phase of the input voltage (θ _M) is estimated based on the detected input current (i _s) and a current gain (K _θ), the current gain (K _θ) in this case is an inductance (L1, L2) of the reactor , Based on the control period T _S and the magnitude V _M component of the input voltage.

On the other hand, the duty generator 420 switches the switching element in the converter 210 based on the current command value I ^* from the current command generator 410 and the phase θ _M from the input voltage estimator 415. The duty d of (S1 or S2) is calculated. For example, the duty generator 420 performs the P control based on the difference between the I ^* cosθ _M value due to the current command value I ^* and the phase θ _M and the detected input current i _s . To generate the duty d. To this end, the duty generator 420 may include a P controller (not shown).

The switching control signal output unit 430 generates a switching control signal Scc, which is a PWM signal, based on the generated duty d and outputs the converted control signal Scc to the converter 210. Accordingly, the switching element S1 or S2 in the converter 210 performs an on / off switching operation.

Meanwhile, the above judgment part 425 judges whether the voltage based on the magnitude of the estimated input voltage (V _M). For example, when one cycle average value or rms value of the estimated input voltage magnitude exceeds the preset allowable value, the abnormality determination unit 425 determines that it is an overvoltage and stops operating as the switching control signal output unit 430. Output the signal Sst.

 When the switching control signal output unit 430 receives the operation stop signal Sst, the switching control signal output unit 430 stops the output of the switching control signal Scc for the converter. Accordingly, burnout of the circuit elements in the driving apparatus 200 may be prevented, and thus the safety of the circuit elements may be secured.

5 is a simplified internal block diagram of the duty generator of FIG. 4.

Referring to the drawings, the duty generator 420 includes a PI controller 510.

The duty d of the duty generator 420 is a sum d _c + d _{n of} the first duty d _c based on the input current component and the second duty d _n based on the nonlinear compensation value. Is determined.

Hereinafter, a method of determining the duty d by the duty generator 420 according to an exemplary embodiment of the present invention will be described.

First, when the switching elements S1 and S1 of FIG. 3 are turned on, the voltage equation becomes Equation 17.

On the other hand, when the switching elements (S1, S1) of Figure 3 is turned off, the voltage equation becomes as shown in equation (18).

Meanwhile, voltages across the reactors L1 and L2 vary according to the duty ratio d of the switching elements S1 and S1 of FIG. 3. When the voltage is defined as V _L , the voltage V _L is As shown in Equation 19, it is expressed as an input current variation di _s during the current control time T _S.

On the other hand, the duty ratio (d), because the ratio of the current control time (T _S) switching element (S1, S1) the turn-on time (T _on) is over, summarized for the equation (19) to the duty ratio (d), It becomes like Equation 20 below.

The duty d in Equation 20 described above may be divided into a first duty d _c based on an input current component and a second duty d _n based on a nonlinear compensation value as shown in Equation 21 below. .

Where Vs is the maximum value of the input voltage and ω represents the angular frequency. The maximum value Vs of the input voltage may be the magnitude V _M of the input voltage estimated by the input voltage estimator 415 based on Equation 15 described above.

First duty (d _c) based on the input current components are proportional to the inductance of the reactor (L1, L2), it is inversely proportional to the dc terminal voltage (Vdc) and the current control period (T _s).

On the other hand, the first duty d _c based on the input current component is calculated from the difference i _err between the current command value I ^* from the current command generation unit 410 and the detected input current i _s . Can be. This is shown in Equation 22 below.

Here, K _pc represents proportional gain and K _ic represents integral gain. K _pc and K _ic are respectively

In summary, the duty generator 420 determines the difference i _err between the current command value I ^* from the current command generator 410 and the detected input current i _{s in} the first adder 505. The first duty d _c is calculated by performing PI control on the difference i _err through the PI controller 510.

Meanwhile, the second duty d _n is determined based on the detected dc terminal voltage Vdc, the maximum value Vs of the input voltage, and the sinusoidal component sinωt of the input voltage, as shown in Equation 21 described above. do.

The first duty d _c and the second duty d _n are summed by the second adder 515 to be output as the duty ratio d.

6 is a simplified block diagram of the inside of the control unit of FIG. 2.

Referring to the drawings, the controller 230 of FIG. 2 may not only output the converter switching control signal Scc but also output the inverter switching control signal Sic.

To this end, the controller 230 may further include an estimator 605, a current command generator 610, a voltage command generator 620, and a switching control signal output unit 630.

On the other hand, although not shown in the drawings, the three-phase output current (io) to convert the d-axis, q-axis current or may further include an axis conversion unit for converting the d-axis, q-axis current to the three-phase current.

The estimation unit 605 estimates the speed v of the electric motor based on the detected output current io. It is also possible to estimate the position of the rotor. This compares the mechanical equations and the electric equations of the motor 250 with each other and thus estimates the speed v of the motor.

The current command generation unit 610 generates the current command values i ^* _d and i ^* _q based on the estimated speed v and the speed command value v ^* . For example, the current command generation unit 610 may generate a current command value i ^* _d , i ^* _q by performing PI control based on the difference between the estimated speed v and the speed command value v ^* . Can be. To this end, the current command generation unit 610 may include a PI controller (not shown). Further, a limiter (not shown) may be further provided to limit the level so that the current command value i ^* _d , i ^* _q does not exceed the allowable range.

The voltage command generator 620 generates the voltage command value v ^* _d , v ^* _q based on the detected output current io and the calculated current command value i ^* _d , i ^* _q . For example, the voltage command generation unit 620 performs PI control based on the difference between the detected output current io and the calculated current command values i ^* _d and i ^* _q to perform a voltage command value v ^*. _d , v ^* _q ) To this end, the voltage command generation unit 620 may include a PI controller (not shown). Further, a limiter (not shown) may be further provided to limit the level so that the voltage command value v ^* _d , v ^* _q does not exceed the allowable range.

The switching control signal output unit 630 generates an inverter switching control signal Sic, which is a PWM signal, based on the voltage command values v ^* _d and v ^* _q and outputs the same to the inverter 220. Accordingly, the switching elements (Sa, S'a, Sb, S'b, Sc, and S'c) of the inverter 220 perform an on / off switching operation.

On the other hand, as described in the description of Figure 4, when the operation stop signal (Sst) is output from the abnormality determination unit 425, not only the output of the switching control signal (Scc) for the converter but also the switching control signal (Sic) for the inverter Can also be stopped. Accordingly, it is possible to prevent burnout of circuit elements including the converter 210 and the inverter 220 in the driving device 200.

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

Referring to the drawings, the motor driving apparatus 700 of the air conditioner of FIG. 7 is almost the same as the motor driving apparatus 200 of the air conditioner of FIG. Therefore, the converter 710, the inverter 720, the controller 730, the input current detector A, the dc terminal voltage detector B, the smoothing capacitor C, and the like in the motor driving apparatus 700 of FIG. 7. The output current detector E is as described with reference to FIG. 2.

However, the motor driving apparatus 700 of the air conditioner of Figure 7 further comprises an LCL filter unit 709 between the commercial AC power source (705, v _s) and a converter (710). In addition, an EMI filter unit 707 may be further provided to reduce EMI from a commercial AC power supply v _s .

The LCL filter unit 709 includes first and second inductors La and L1 connected in series to each other, and third and third connected in series to remove harmonic currents such as a ripple component of the input current i _s . Four inductors Lb and L2 and first capacitors Ca connected in parallel with the first and second inductors La and L1 may be provided. The first capacitor Ca is connected between the first and second inductors La and L1 and the third and fourth inductors Lb and L2.

Thereby, the high frequency current due to the harmonic of the input current (i _s) is limited by the inductor Ingredients (jwL), low frequency current due to the harmonic of the input current (i _s) is limited by the capacitor element (1 / jwC) Will be.

Meanwhile, the LCL filter unit 709 may further include a damping resistor Ra having one end connected to the first capacitor Ca in order to prevent a resonance phenomenon in the motor driving apparatus. The damping resistance Ra lowers the goodness Q and widens the bandwidth, thereby improving stability.

As a result, the LCL filter unit 709 can limit the harmonic current of the harmonics generated by the high-speed switching of the converter 710, so as to comply with the harmonic regulation such as IEC 61000-3, which is a European harmonic standard. It becomes possible.

The operation of the motor driving apparatus 700 of the air conditioner of FIG. 7 is the same as that of the motor driving apparatus of the air conditioner of FIG. In particular, the controller 730 includes a duty generator 420 as shown in FIG. 5, and the operation thereof is also the same as that described with reference to FIG. 5. Thus, the duty d is generated based on the input current i _s . Meanwhile, the converter 710 may be the same as illustrated in FIG. 3.

8 is a diagram illustrating a detection input current according to the driving apparatus of FIGS. 2 and 7.

Referring to the drawings, as described above in the description of FIG. 7, the input current i _s of the driving device 700 of FIG. 7 having the LCL filter is more current ripple than that of FIG. It can be seen that it was removed. Accordingly, more accurate input voltage estimation may be performed when the input voltage is estimated, and further, overall circuit stability in the driving apparatus 700 is further secured.

9 is a diagram illustrating an input power factor of a converter according to the operation of the motor of FIG. 2.

Referring to the drawings, although the operating frequency of the motor 250 is variable, it can be seen that the input power factor of the converter 210 is at least 95% or more. This is an experimental example of the case in which the duty generator 420 shown in FIG. 5 calculates the duty to output the converter switching control signal Scc. According to this, the input power factor can be stably secured despite the load variation during the operation of the motor 250.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention 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 driving apparatus according to an embodiment of the present invention.

3 is a circuit diagram illustrating an example of the converter of FIG. 2.

4 is a simplified block diagram of the inside of the controller of FIG. 2.

FIG. 5 is a diagram illustrating an input voltage estimated by the input voltage estimating unit of FIG. 4.

6 is a simplified block diagram of the inside of the control unit of FIG. 2.

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

8 is a diagram illustrating a detection input current according to the driving apparatus of FIGS. 2 and 7.

9 is a diagram illustrating an input power factor of a converter according to the operation of the motor of FIG. 2.

<Explanation of symbols on main parts of the drawings>

210: converter 220: inverter

230: controller 415: input voltage estimation unit

420: duty generator 425: abnormality determination unit

320: voltage command generation unit 330: switching control signal output unit

A: input current detector B: dc stage voltage detector

E: output current detector

Claims (14)

A converter having a switching element and converting the input AC power into a DC power by a switching operation; An input current detector for detecting an input current from the input AC power supply; An inverter having a plurality of switching elements and converting the DC power into AC power of a predetermined frequency by a switching operation to drive an electric motor; And And a controller configured to determine a duty of the switching element of the converter based on the detected input current and output a converter switching control signal for driving the switching element of the converter according to the determined duty. The duty is, And a sum of a first duty based on the input current component and a second duty that is a nonlinear compensation value. The method of claim 1, The control unit, A current command generation unit that generates a current command value based on the detected value of the dc end voltage and the dc end voltage command value as the converter output terminal; A duty generator configured to generate the duty of the switching control signal of the converter based on the current command value and the detected input current; And And a switching control signal output unit configured to generate and output the converter switching control signal on the basis of the generated duty. The method of claim 2, The first duty, And controlling the difference between the current command value and the detected input current by PI control. The method of claim 2, The second duty, And an electric motor drive device for an air conditioner, based on a detected value of the dc terminal voltage, a maximum value of an input voltage from the input AC power supply, and a sine wave component of the input voltage. The method of claim 1, And a reactor connected between the input AC power source and the converter. And said duty is determined based on said detected input current, inductance of said reactor, and a control period. The method of claim 2, The control unit, And an input voltage estimator for estimating a magnitude and a phase of the input voltage based on the detected input current. The method of claim 6, And a reactor connected between the input AC power source and the converter. The magnitude of the input voltage is determined based on the detected input current, inductance and control period of the reactor, And the phase of the input voltage is determined based on the detected input current, the inductance of the reactor, the control period, and the magnitude of the input voltage. The method of claim 6, The control unit, And an abnormality determining unit determining whether an overvoltage is detected based on the estimated magnitude of the input voltage. And stopping the output of the switching control signal from the switching control signal output unit when the overvoltage is determined. The method of claim 1, The converter, First and second diode elements connected in series with each other; Third and fourth diode elements connected in parallel with the first and second diode elements and connected in series with each other; And First and second switching elements connected in parallel to both ends of the second and fourth diode elements, respectively. 10. The method of claim 9, The converter, And first and second resistor elements connected to one end of the second and fourth diode elements, respectively, and connected in parallel to each other. The method of claim 1, And an LCL filter unit including first and second inductors connected in series between the input AC power source and the converter, and first capacitors connected in parallel between the first and second inductors. An electric motor drive device of an air conditioner. The method of claim 11, The LCL filter unit And a damping resistor connected to one end of the first capacitor. The method of claim 1, And an output current detector for detecting an output current flowing between the inverter and the motor. The control unit, the motor driving apparatus of the air conditioner, characterized in that for outputting an inverter switching control signal for driving the switching elements of the inverter. The method of claim 11, The control unit, An estimator estimating a speed of the electric motor based on the detected 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 detected output current; And And a switching control signal output unit configured to generate and output the inverter switching control signal based on the voltage command value.

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