KR102242773B1 - Motor driving device and air conditioner including the same - Google Patents

Abstract

The present invention relates to an electric motor driving device and an air conditioner having the same. An electric motor driving apparatus according to an embodiment of the present invention includes a plurality of switching elements, an inverter that converts pulsating pulsating power and outputs the converted DC power to a motor, and a control unit that controls the inverter. , Based on the speed and torque of the motor, the system is controlled to operate in a first mode for performing system current shaping or a second mode for not performing system current shaping. Accordingly, it is possible to reduce harmonics and improve motor efficiency.

Description

Motor driving device and air conditioner including the same

The present invention relates to an electric motor driving apparatus and an air conditioner having the same, and more particularly, to an electric motor driving apparatus capable of reducing harmonics and improving motor efficiency in an electric motor driving apparatus using a low-capacity capacitor, and an air conditioner having the same. will be.

The air conditioner is installed to provide a more comfortable indoor environment to humans by discharging cold and hot air into the room to create a pleasant indoor environment, adjusting the indoor temperature, and purifying the indoor air. In general, an air conditioner includes an indoor unit configured as a heat exchanger and installed indoors, and an outdoor unit configured with a compressor and a heat exchanger to supply refrigerant to the indoor unit.

Meanwhile, an electric motor is used in an air conditioner. Recently, various methods for efficient power consumption have been devised in consideration of environmental issues. Accordingly, the use of a synchronous motor (SM), in particular a permanent magnet synchronous motor (PMSM) is increasing.

On the other hand, when driving an electric motor, in order to reduce manufacturing cost, etc., a low-capacity capacitor is being used. However, when a capacitor having a low capacity is used, the voltage across the capacitor pulsates, and as a result, there is a problem in that the harmonic of the system current increases.

An object of the present invention is to provide an electric motor driving apparatus capable of reducing harmonics and improving motor efficiency in an electric motor driving apparatus using a low-capacity capacitor, and an air conditioner having the same.

An electric motor driving apparatus according to an embodiment of the present invention for achieving the above object includes a plurality of switching elements, an inverter that converts pulsating pulsating power to output the converted DC power to a motor, and a control unit that controls the inverter. Including, the control unit, based on the speed and torque of the motor, the first mode for performing the grid current shaping (shaping) or the second mode not performing the grid current shaping, and controls to operate.

In addition, an air conditioner according to an embodiment of the present invention for achieving the above object includes a compressor for compressing a refrigerant, a heat exchanger for performing heat exchange using the compressed refrigerant, and a compressor motor driving device for driving a motor in the compressor. Including, the compressor motor driving apparatus includes a plurality of switching elements, the inverter for converting the pulsating pulsating power to output the converted DC power to the motor, and a control unit for controlling the inverter, the control unit, the motor Based on the speed and torque of, the system is controlled to operate in a first mode that performs system current shaping or a second mode that does not perform system current shaping.

According to an embodiment of the present invention, an electric motor driving device and an air conditioner having the same, based on the speed and torque of the motor, a first mode for performing system current shaping or a first mode not performing system current shaping. By operating in two modes, it becomes possible to reduce harmonics and improve motor efficiency.

In particular, when the motor output is higher than a predetermined value, harmonics are reduced by the system current shaping, and when the motor output is less than the predetermined value, the system current shaping is not performed and the motor efficiency is maximized, thereby improving motor efficiency. do.

On the other hand, since it is possible to use a small-capacity film capacitor with a long life, the reliability of the motor driving device is improved, and the manufacturing cost and the volume thereof are reduced.

1 is a diagram illustrating a configuration of an air conditioner according to an embodiment of the present invention.
2 is a schematic diagram of the outdoor unit and the indoor unit of FIG. 1.
3 is a circuit diagram showing an example of an electric motor driving apparatus according to an embodiment of the present invention.
4 is an internal block diagram of the control unit of FIG. 3.
5 is a diagram illustrating a dc terminal voltage according to the capacity of the capacitor of FIG. 3.
6 is a diagram illustrating a first mode and a second mode compared to the speed and torque of an electric motor.
7 is an internal block diagram of the control unit of FIG. 3 according to an embodiment of the present invention.
8A is an internal block diagram of a first mode operation unit of FIG. 7.
8B is an internal block diagram of a second mode operation unit of FIG. 7.
9 is an internal block diagram of a power command generation unit of FIG. 8A.
10A illustrates waveforms of a dc voltage and a grid current according to a first mode.
10B illustrates waveforms of a dc voltage and a grid current according to the second mode.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

The suffixes "module" and "unit" for the constituent elements used in the following description are given in consideration of only the ease of writing in the present specification, and do not impart a particularly important meaning or role by themselves. Therefore, the "module" and "unit" may be used interchangeably with each other.

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

The air conditioner 100 according to the present invention may include an indoor unit 31 and an outdoor unit 21 connected to the indoor unit 31 as shown in FIG. 1.

The indoor unit 31 of the air conditioner can be applied to any of a stand type air conditioner, a wall-mounted type air conditioner, and a ceiling type air conditioner, but in the drawings, the stand type indoor unit 31 is illustrated.

Meanwhile, the air conditioner 100 may further include at least one of a ventilation device, an air cleaning device, a humidifying device, and a heater, and may operate in conjunction with the operation of the indoor unit and the outdoor unit.

The outdoor unit 21 includes a compressor (not shown) that receives and compresses a refrigerant, an outdoor heat exchanger (not shown) that exchanges heat between the refrigerant and outdoor air, and an accumulator (not shown) that extracts gaseous refrigerant from the supplied refrigerant and supplies it to the compressor. Si) and a four-way valve (not shown) for selecting a flow path of the refrigerant according to the heating operation. In addition, a plurality of sensors, valves, oil collectors, and the like are further included, but a description of the configuration thereof will be omitted below.

The outdoor unit 21 operates an installed compressor and an outdoor heat exchanger to compress or heat exchange the refrigerant according to a setting to supply the refrigerant to the indoor unit 31. The outdoor unit 21 may be driven by a remote controller (not shown) or a demand of the indoor unit 31. In this case, as the cooling/heating capacity is varied in correspondence with the driven indoor unit, the number of operation of the outdoor unit and the number of operation of the compressor installed in the outdoor unit may be varied.

At this time, the outdoor unit 21 supplies the compressed refrigerant to the connected indoor unit 310.

The indoor unit 31 receives a refrigerant from the outdoor unit 21 and discharges cold and hot air into the room. The indoor unit 31 includes an indoor heat exchanger (not shown), an indoor unit fan (not shown), an expansion valve (not shown) through which the supplied refrigerant is expanded, and a plurality of sensors (not shown).

At this time, the outdoor unit 21 and the indoor unit 31 are connected by a communication line to transmit and receive data, and the outdoor unit and the indoor unit are connected by wire or wirelessly to a remote controller (not shown) and operate according to the control of a remote controller (not shown). can do.

A remote control (not shown) may be connected to the indoor unit 31, input a user's control command to the indoor unit, and receive and display status information of the indoor unit. In this case, the remote control may communicate by wire or wirelessly depending on the connection type with the indoor unit.

2 is a schematic diagram of the outdoor unit and the indoor unit of FIG. 1.

Referring to the drawings, the air conditioner 100 is largely divided into an indoor unit 31 and an outdoor unit 21.

The outdoor unit 21 includes a compressor 102 that compresses a refrigerant, a compressor motor 102b that drives the compressor, an outdoor heat exchanger 104 that dissipates the compressed refrigerant, and an outdoor unit. An outdoor blower 105 composed of an outdoor fan 105a that is disposed on one side of the heat exchanger 104 to promote heat dissipation of the refrigerant and an electric motor 105b that rotates the outdoor fan 105a, and expansion to expand the condensed refrigerant The mechanism 106, the cooling/heating switching valve 110 for changing the flow path of the compressed refrigerant, and an accumulator 103 that temporarily stores the gasified refrigerant to remove moisture and foreign matter, and then supplies a refrigerant having a constant pressure to the compressor. And the like.

The indoor unit 31 includes an indoor heat exchanger 109 disposed indoors to perform a cooling/heating function, an indoor fan 109a disposed at one side of the indoor heat exchanger 109 to promote heat dissipation of the refrigerant, and And an indoor blower 109 made of an electric motor 109b that rotates the fan 109a.

At least one indoor heat exchanger 109 may be installed. At least one of an inverter compressor and a constant speed compressor may be used as the compressor 102.

In addition, the air conditioner 100 may be composed of a cooler that cools the room, or may be configured with a heat pump that cools or heats the room.

The compressor 102 in the outdoor unit 21 of FIG. 1 may be driven by a compressor motor driving device (200 of FIG. 3) that drives the compressor motor 250.

3 is a circuit diagram showing an example of an electric motor driving apparatus according to an embodiment of the present invention.

Referring to the drawings, the motor driving apparatus 200 of FIG. 3 according to an embodiment of the present invention includes a rectifying unit 210, an inverter 220, a control unit 230, a grid current detection unit A, and a single DC voltage. It may include a detection unit (B), a DC terminal capacitor (C), and an electric motor current detection unit (E), a system voltage detection unit (F). In addition, the electric motor driving apparatus 200 of FIG. 3 may further include reactors L1 and L2.

The reactors L1 and L2 are disposed between the commercial AC power supply 205 and v _g and the rectifier 210 to perform an operation such as noise removal.

The system current detection unit A can detect _{the system current i g} input from the commercial AC power supply 205. To this end, as the system current detection unit A, a current trnasformer (CT), a shunt resistor, or the like may be used. The detected system current i _g is a discrete signal in the form of a pulse and may be input to the controller 230 for power control.

The system voltage detection unit F can detect _{the system voltage v g} input from the commercial AC power supply 205. To this end, the system voltage detection unit F may include a resistance element, an amplifier, and the like. The detected system voltage v _g is a discrete signal in the form of a pulse and may be input to the controller 230 for power control.

The rectifying unit 210 rectifies and outputs the commercial AC power supply 205 that has passed through the reactors L1 and L2. For example, the rectifier 210 may include a full bridge diode to which four diodes are connected, but various modifications are possible.

The capacitor C stores input power. In the drawings, one device is illustrated as a DC-link capacitor C, but a plurality of devices are provided to ensure device stability.

Meanwhile, the DC link capacitor C in the present specification is a small-capacity capacitor, and may be a capacitorless type capacitor. That is, the capacitor C may be a film type capacitor, not an electrolytic capacitor. By using such a capacitorless type capacitor, the stability of the motor driving device is improved, and the manufacturing cost and the volume thereof are reduced.

Meanwhile, since DC power is stored at both ends of the capacitor C, it may be referred to as a dc terminal or a dc link terminal.

The dc terminal voltage detector B may detect the dc terminal voltage Vdc, which is both ends of the capacitor C. To this end, the dc terminal voltage detection unit B may include a resistance element, 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 inverter switching control signal Sic.

The inverter 220 includes a plurality of inverter switching elements, converts the rectified power Vdc into a three-phase AC power supply (va, vb, vc) having a predetermined frequency, and outputs it to the three-phase motor 250.

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

The switching elements in the inverter 220 perform on/off operations of each switching element based on the inverter switching control signal Sic from the controller 230. Accordingly, the three-phase AC power supply (va, vb, vc) having a predetermined frequency is output to the three-phase motor 250.

The controller 230 may control a switching operation of the inverter 220. To this end, the controller 230 may receive an _{output current i o} flowing to the motor detected by the motor current detection unit E.

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, which is generated and output based _{on the output current value i o detected from the motor current detection unit E.} A detailed operation of the output of the inverter switching control signal Sic in the controller 230 will be described later with reference to FIG. 4.

_{The motor current detection unit E detects an output current i o} flowing between the inverter 220 and the three-phase motor 250. That is, the current flowing through the three-phase electric motor 250 is detected. The motor current detection unit E may detect all of the output currents ia, ib, ic of each phase, or may detect the output currents of two phases using three-phase equilibrium.

The motor current detection unit E may be located between the inverter 220 and the three-phase motor 250, and for current detection, a current trnasformer (CT), a shunt resistor, or the like may be used.

When a shunt resistor is used, three shunt resistors are located between the inverter 220 and the three-phase motor 250, or the three lower arm switching elements (S'a, S'b, S'c) of the inverter 220 ) Can be connected to each end. On the other hand, using three-phase equilibrium, it is also possible to use two shunt resistors. Meanwhile, when one shunt resistor is used, a corresponding shunt resistor may be disposed between the capacitor C and the inverter 220 described above.

The detected output current i _o may be applied to the control unit 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 do. Hereinafter, it is assumed that the detected output current i _o is the three-phase output current ia, ib, ic.

On the other hand, the three-phase electric motor 250 includes a stator and a rotor, and each phase AC power of a predetermined frequency is applied to the coils of the stator of each phase (a, b, c phase), so that the rotor rotates. Will do.

Such a three-phase motor 250 is, for example, a surface-mounted permanent magnet synchronous motor (Surface-Mounted Permanent-Magnet Synchronous Motor; SMPMSM), a built-in permanent magnet synchronous motor (Interior Permanent Magnet Synchronous Motor; IPMSM), and synchronous It may include a reluctance motor (Synchronous Reluctance Motor; Synrm), or the like.

Among them, SMPMSM and IPMSM are Permanent Magnet Synchronous Motor (PMSM), and Synrm is characterized by no permanent magnet.

On the other hand, in relation to the embodiment of the present invention, the control unit 230 may be configured in a first mode for performing grid current shaping or a second mode for not performing grid current shaping, based on the speed and torque of the motor. , Can be controlled to operate.

In particular, during the first mode operation, the controller 230 may perform system current shaping so that the system current corresponds to the pulsating voltage.

The control unit 230 is provided with a mode selection unit (410 in Fig. 7) for selecting any one of the first mode and the second mode based on the speed calculated based on the output current flowing through the motor and the torque command value. I can.

The control unit 230 may further include a torque command generation unit (325 in FIG. 7) that generates a torque command value based on the calculated speed and speed command value.

The control unit 230 may further include a first mode operation unit (420 in FIG. 7) for operating the motor in a first mode, and a second mode operation unit (430 in FIG. 7) for operating the motor in a second mode. I can.

The first mode operation unit (420 in Fig. 7) includes a current command generation unit (330 in Fig. 8A) that generates a current command value based on the torque command value, and a voltage that generates a first voltage command value based on the current command value. A command generation unit (340 in Fig. 8A), a power command generation unit (520 in Fig. 8A) that generates a power command value based on a torque command value, and a power controller (Fig. A switching control signal output unit (360 in FIG. 8A) for outputting a switching control signal based on 525 of 8A and the first and second voltage command values may be provided. At this time, the system current control of the inverter, that is, shaping, in consideration of the pulsating dc end voltage by the second voltage command value based on the power command generation unit (520 in Fig. 8A) and the power controller (525 in Fig. 8A). This becomes possible.

The second mode operation unit (430 in Fig. 7) includes a current command generation unit (330 in Fig. 8B) that generates a current command value, and a voltage command generation unit (340 in Fig. 8B) that generates a voltage command value based on the current command value. ), and a switching control signal output unit (360 in FIG. 8B) that outputs a switching control signal based on the voltage command value. In this case, the system current control in consideration of the pulsating dc voltage is not performed, but in response to the load, the motor can operate with maximum efficiency.

On the other hand, the control unit 230, the system current (i _{g ) detected by the system current detection unit (A), the system voltage (v g} ) detected by the system voltage detection unit (F), and the DC terminal voltage detection unit (B) Power control is performed based on the dc voltage (Vdc) and the output current (i _{o) detected by the motor current detector (E).}

4 is an internal block diagram of the control unit of FIG. 3.

Referring to FIG. 4, the control unit 230 includes an axis conversion unit 310, a position estimation unit 320, a current command generation unit 330, a voltage command generation unit 340, an axis conversion unit 350, and A switching control signal output unit 360 may be included.

The axis conversion unit 310 receives the three-phase output current (ia, ib, ic) detected by the output current detection unit E and converts it into a two-phase current (iα, iβ) of the stationary coordinate system.

Meanwhile, the axis conversion unit 310 may convert the two-phase currents iα and iβ of the stationary coordinate system into the two-phase currents id and iq of the rotational coordinate system.

)에 기초하여, 추정된 속도(

)를 추청할 수 있다.The position estimating unit 320 receives the two-phase currents iα and iβ of the stationary coordinate system and the two-phase voltages vα and vβ of the stationary coordinate system and estimates the rotor position θ. In addition, the position estimation unit 320, the estimated position value (

), the estimated speed (

) Can be estimated.

At this time, the two-phase current (iα, iβ) of the stationary coordinate system may be input from the axis conversion unit 310, and the two-phase voltage (vα,vβ) of the stationary coordinate system is the dc terminal from the dc stage voltage detector (B). It may be calculated in consideration of the voltage Vdc and the switching operation state of the inverter 220. For example, according to the dc end voltage (Vdc) from the dc end voltage detector (B) and the switching operation state of the inverter 220, the three-phase output voltage (va, vb, vc) is calculated by a predetermined relational expression. Then, the axis conversion unit 310 may be converted back to the two-phase voltages vα and vβ of the stationary coordinate system.

)와 추정된 속도(

)를 출력할 수 있다.On the other hand, the position estimation unit 320, the position estimated under the stationary coordinate system (

) And estimated speed (

) Can be printed.

)를 연산할 수 있다. 즉, 위치 신호에 기반하여, 시간에 대해, 나누면, 속도를 연산할 수 있게 된다. 이하에서는, 위치 추정부(320)를 중심으로 기술한다.Meanwhile, in FIG. 4, for detecting the rotor position, a sensorless type position estimation unit 320 without a separate sensor is illustrated. Unlike this, when a position detection sensor such as a Hall sensor is used, a position weight The government 320 can be replaced with a speed calculation unit (not shown). That is, when the position signal detected by the Hall sensor is input to the speed calculating unit (not shown), based on the position signal, the speed (

) Can be calculated. That is, based on the position signal, it is possible to calculate the speed by dividing it with respect to time. Hereinafter, a description will be given based on the position estimation unit 320.

)와 연산된 속도(

)를 출력할 수 있다.On the other hand, the position estimation unit 320, the position calculated based on the input position signal (H) of the rotor (

) And calculated speed (

) Can be printed.

)와 속도 지령치(ω^* _r)에 기초하여, 전류 지령치(i^* _q)를 생성한다. 예를 들어, 전류 지령 생성부(330)는, 연산 속도(

)와 속도 지령치(ω^* _r)의 차이에 기초하여, PI 제어기(335)에서 PI 제어를 수행하며, 전류 지령치(i^* _q)를 생성할 수 있다. 도면에서는, 전류 지령치로, q축 전류 지령치(i^* _q)를 예시하나, 도면과 달리, d축 전류 지령치(i^* _d)를 함께 생성하는 것도 가능하다. 한편, d축 전류 지령치(i^* _d)의 값은 0으로 설정될 수도 있다. On the other hand, the current command generation unit 330, the calculation speed (

) And the speed command value (ω ^* _r ), the current command value (i ^* _q ) is generated. For example, the current command generation unit 330, the calculation speed (

) And the speed command value (ω ^* _r ), the PI controller 335 performs PI control, and a current command value (i ^* _q ) can be generated. In the drawing, the q-axis current command value (i ^* _q ) is illustrated as the current command value, but unlike the drawing, it is also possible to generate the ^{d-axis current command value (i *} _{d) together.} Meanwhile, the value of the d-axis current command value (i ^* _d ) may be set to 0.

Meanwhile, the current command generation unit 330 may further include a limiter (not shown) that limits the level of the ^{current command value i *} _{q so that it does not exceed the allowable range.}

Next, the voltage command generation unit 340 includes the d-axis and q-axis currents (i _d , i _q ) that have been axially transformed from the axis conversion unit into a two-phase rotational coordinate system, and a current command value ( Based on i ^* _d ,i ^* _q ), the d-axis and q-axis voltage command values (v ^* _d ,v ^* _q ) are generated. For example, the voltage command generation unit 340 performs PI control in the PI controller 344 based on the difference between the _{q-axis current (i q} ) and the q-axis current command value (i ^* _{q ), and q} It is possible to generate the axis voltage command value (v ^* _{q ).} Further, the voltage command generation unit 340 performs PI control in the PI controller 348 based on the difference between the _{d-axis current (i d} ) and the d-axis current command value (i ^* _{d ), and the d-axis voltage} You can create a setpoint (v ^* _{d ).} Meanwhile, the value of the d-axis voltage command value (v ^* _d ) may be set to 0 corresponding to the case where the value of the d-axis current command value (i ^* _{d) is set to 0.}

Meanwhile, the voltage command generation unit 340 may further include a limiter (not shown) that limits the level of the d-axis and q-axis voltage command values (v ^* _d , v ^* _{q) to not exceed the allowable range.} .

On the other hand, the generated d-axis and q-axis voltage command values (v ^* _d and v ^* _q ) are input to the axis conversion unit 350.

)와, d축, q축 전압 지령치(v^* _d,v^* _q)를 입력받아, 축변환을 수행한다.The axis conversion unit 350 is a position calculated by the position estimating unit 320 (

) And the d-axis and q-axis voltage command values (v ^* _d ,v ^* _q ) and perform axis transformation.

)가 사용될 수 있다.First, the axis conversion unit 350 converts from a two-phase rotational coordinate system to a two-phase stationary coordinate system. At this time, the position calculated by the position estimating unit 320 (

) Can be used.

In addition, the axis conversion unit 350 converts from a two-phase stationary coordinate system to a three-phase stationary coordinate system. Through this conversion, the axis conversion unit 2050 outputs a three-phase output voltage command value (v ^* a, v ^* b, v ^* c).

The switching control signal output unit 360 generates a switching control signal Sic for an inverter according to a pulse width modulation (PWM) method based on a three-phase output voltage command value (v ^* a, v ^* b, v ^{* c).} And print it out.

The output inverter switching control signal Sic may be converted into a gate driving signal in a gate driver (not shown) and may be input to the gates of each switching element in the inverter 220. Accordingly, each of the switching elements Sa, S'a, Sb, S'b, Sc, S'c in the inverter 220 performs a switching operation.

5 is a diagram illustrating a dc terminal voltage according to the capacity of the capacitor of FIG. 3.

First, FIG. 5A illustrates a DC terminal voltage waveform Vdc1 when an electrolytic capacitor having a large capacity is used as the DC terminal capacitor C.

Next, (b) of FIG. 5 illustrates the dc terminal voltage waveform Vdc2 when a small-capacity film-type capacitor is used as the dc terminal capacitor C.

As shown in (b) of FIG. 5, when a capacitor-less type capacitor is used, since the capacitance is small, the smoothing function is deteriorated, and the variability of the dc voltage is significantly greater than that of (a) of FIG. 5.

Equation 1 below shows the relationship between input power (Pg), dc stage power (Pdc), and inverter output power (Pinv).

,

는 각각 전동기에 인가되는 전압 벡터와 전동기에 흐르는 전류 벡터를 의미하며, θ_vi는 전압 벡터(

)와 전류 벡터(

)의 위상 차이를 나타낸다.Here, Cdc represents a dc single capacitor,

,

Is the voltage vector applied to the motor and the current vector flowing to the motor, respectively, and θ _vi is the voltage vector (

) And the current vector (

) Represents the phase difference.

In the case of a general inverter, since the DC terminal capacitor C of FIG. 5A has a sufficient capacity to sufficiently compensate for the difference in power, the desired inverter output power (Pinv) can be adjusted without considering the input power (Pg). Can be printed.

However, as shown in (b) of FIG. 5, when a small-capacity DC-link capacitor is used, since the size of the dc-stage power (Pdc) is limited by the capacity of the dc-stage capacitor (C), the input power (Pg) and the inverter output power ( Pinv) difference cannot be sufficiently compensated.

Particularly, when a single-phase input power supply is used, a large pulsation component of the input power Pg generated by this remains in the inverter output power Pinv, which may cause pulsation of the motor output.

In an embodiment of the present invention, in an electric motor driving apparatus using a capacitorless type capacitor, the motor is driven in consideration of the highly variable dc voltage (Vdc), but it is possible to reduce harmonics to the system current and improve motor efficiency. Present a plan.

6 is a diagram illustrating a first mode and a second mode compared to the speed and torque of an electric motor.

Referring to the drawings, in the present invention, according to the speed and torque of the electric motor 250, a first mode for performing current shaping and a second mode for not performing current shaping are classified.

In particular, since the product of the speed and torque of the motor 250 is proportional to the output of the motor, when the output of the motor is more than a predetermined value, it operates in the first mode, and when it is less than the predetermined value, it operates in the second mode. can do.

In particular, when the motor output is large, since the harmonic component of the system current may increase according to the pulsation of the dc stage, current shaping is performed to reduce the harmonic component. That is, in consideration of the pulsating dc stage, the inverter can be controlled.

On the other hand, when the motor output is small, since the pulsation of the dc stage is relatively small, the harmonic component of the system current may be negligible. In this case, by controlling the inverter to maximize the efficiency of the motor, it is possible to improve the motor efficiency.

7 is an internal block diagram of the control unit of FIG. 3 according to an embodiment of the present invention, FIG. 8A is an internal block diagram of the first mode operation unit of FIG. 7, and FIG. 8B is an internal block diagram of the second mode operation unit of FIG. 7. to be.

Referring to the drawings, according to an embodiment of the present invention, the controller 230 is based on the speed and torque of the motor, a first mode for performing system current shaping or a second mode for not performing system current shaping. Mode, you can control it to operate.

In particular, during the first mode operation, the controller 230 may perform system current shaping so that the system current Ig corresponds to the pulsating voltage.

), 및 토크 지령치(T^*)에 기초하여, 제1 모드와 제2 모드 중 어느 하나를 선택하는 모드 선택부(410)를 구비할 수 있다.The control unit 230 also calculates a speed calculated based on the output current Io flowing through the motor (

), and a torque command value (T ^* ), a mode selector 410 for selecting one of the first mode and the second mode may be provided.

)와 속도 지령치(ω^* _r)에 기초하여 토크 지령치(T^*)를 생성하는 토크 지령 생성부(325)를 더 포함할 수 있다.The control unit 230 is also the calculated speed (

) And a torque command generation unit 325 that generates a torque command ^{value T *} based on the speed command value ω ^* _{r ).}

The controller 230 may further include a first mode operation unit 420 for operating the motor in a first mode, and a second mode operation unit 430 for operating the motor in a second mode.

The first mode operation unit 420 includes a current command generation unit 330 that generates a current command value (I ^{* ) based on the torque command value (T * ), and a first mode based on the current command value (I *} ). A voltage command generation unit 340 that generates a voltage command value (V ^* ₁ ), a power command generation unit 520 that generates a power command value (P ^{* ) based on a torque command value (T * ), and a power command value (P *} ), based on the power controller 525 generating a second voltage command value (V ^* ₂ ), and the first and second voltage command values ((V ^* ₁ ,V ^* ₂ ), based on the switching control signal ( Sic) may be provided with a switching control signal output unit 360. At this time, pulsating by ^{a second voltage command value (V *} _{2) based on the power command generation unit 520 and the power controller 525} In consideration of the dc voltage (Vdc), the grid current control of the inverter 220, that is, shaping is possible.

The second mode operation unit 430 includes a current command generation unit 330 that generates a current command ^{value (I *} ), and a voltage command generation unit 340 that generates a voltage command ^{value (V *) based on the current command value.} Wow, on the basis of the voltage command value (V ^* ), it may be provided with a switching control signal output unit 360 for outputting the switching control signal (Sic). In this case, the system current control in consideration of the pulsating dc voltage is not performed, but in response to the load, the motor can operate with maximum efficiency.

Meanwhile, the torque command generation unit 325 in the control unit 230 may output a torque command value T ^* for rotation of the electric motor based on the speed command and the calculated speed value. In particular, the torque command generation unit 325 can output an average torque command value. Meanwhile, the calculated speed may be calculated based on the above-described output current i _o flowing to the electric motor or a position signal.

The current command generation unit 330 may generate a current command ^{value I *} based on the ^{torque command value T *} . Here, the current command value (I ^* ) may mean including the d-axis current command value and the q-axis current command value of the synchronous coordinate system.

Next, the voltage command generation unit 340 may generate a voltage command ^{value V * based on the current command value I *} and the output current flowing to the actual motor. Here, the voltage command value (V ^* ) may mean including a d-axis voltage command value and a q-axis voltage command value of the synchronous coordinate system.

Next, the switching control signal output unit 360 may output a switching control signal for controlling the switching element in the inverter 120 based on the ^{voltage command value (V * ).}

Meanwhile, the second mode operation unit 430 of FIG. 8B is a mode, which is performed when the motor output is less than a predetermined value, and does not take into account the dc voltage, particularly, the voltage Vdc stored in the capacitor C. It's the way.

Accordingly, in the case of using the capacitor-less type capacitor (C), since the magnitude of the voltage at the dc terminal is small, it is possible to maximize the efficiency when driving the motor.

On the other hand, when the output of the motor increases, if the motor is driven in the second mode as shown in FIG. 8B, there is no power control, and thus accurate power compensation control is not performed.

In particular, due to the limit of the PI controller in the voltage command generation unit 340, the output voltage limit may be exceeded, and accordingly, the power factor may be lowered and the motor operation region may be limited. Accordingly, when the motor output is greater than or equal to a predetermined value, the motor operates in a first mode capable of controlling power.

The control unit 230 of FIG. 8A includes a torque command generation unit 325, a power command generation unit 520, a power controller 525, a current command generation unit 330, a voltage command generation unit 340, and an adder 555. ), and a switching control signal output unit 360. Meanwhile, the axis conversion unit 310, the axis conversion unit 350, and the position estimation unit 320 described in FIG. 4 may be further provided. In the following, the units described in FIG. 8A will be mainly described.

)와 속도 지령치(ω^* _r)에 기초하여, 전동기의 회전을 위한, 토크 지령치(T^*)를 출력할 수 있다. 특히, 토크 지령 생성부(325)는, 평균 토크 지령치를 출력할 수 있다. 한편, 연산 속도(

)는, 상술한, 전동기(250)에 흐르는 출력 전류(i_o), 또는 위치 신호에 기반하여, 연산될 수 있다.The torque command generation unit 325 is a calculation speed (

) And the speed command value (ω ^* _r ), it is possible to output the ^{torque command value (T *} ) for the rotation of the electric motor. In particular, the torque command generation unit 325 can output an average torque command value. Meanwhile, the computational speed (

) May be calculated based on the above-described output current i _{o flowing through the electric motor 250 or a position signal.}

The current command generation unit 330 may generate a current command ^{value I *} based on the ^{torque command value T *} . Here, the current command value (I ^* ) may mean including the d-axis current command value and the q-axis current command value of the synchronous coordinate system.

The voltage command generation unit 340 may generate ^{the first voltage command value V *} ₁ ^{based on the current command value I *} and the output current flowing to the actual motor. Here, the first voltage command value (V ^* ₁ ) may mean including the d-axis voltage command value and the q-axis voltage command value of the synchronous coordinate system.

Meanwhile, in relation to the field weakening current, the current command generation unit 330 may output a current command value corresponding to the field weakening control to the voltage command generation unit 340 during field weakening control.

), 및 dc 단 전압 검출부에서 검출된 dc 단 전압(Vdc)에 기초하여, 출력 전력 지령치(P^*)를 생성하여 출력한다. 특히, 인버터(220)에서 출력 가능한 인버터 출력 전력 지령치(P^*inv)를 생성하여 출력한다. 본 명세서에서는, 전력 지령 생성부(520)에서 생성되는 출력 전력 지령치에 대해, P^* 와 P^*inv 를 혼용하여 사용하나, 그 의미는 동일하다.On the other hand, the power command generation unit 520, the system voltage (Vg), the torque command value (T ^* ), the calculation speed (

^{), and the output power command value (P *} ) is generated and output based on the dc end voltage (Vdc) detected by the dc end voltage detector. In particular, the inverter 220 generates and outputs an inverter output power command value (P ^* inv) that can be output. In this specification, for the output power command value generated by the power command generation unit 520, P ^* and P ^* inv Is used interchangeably, but the meaning is the same.

)와, 계통 전압(Vg)의 위상을 이용하여, 입력 전력의 순시치(P^*g)를 산출한다.Specifically, the power command generation unit 520 includes a torque command value (T ^* ) that is an output of the torque command generation unit 325 and the calculated current motor speed (

) And the phase of the system voltage (Vg), the instantaneous value (P ^* g) of the input power is calculated.

On the other hand, in order to drive the capacitorless inverter, since the power change due to the DC voltage fluctuation must be considered, the power command generation unit 520 also includes an instantaneous value of the DC end power in addition to ^{the instantaneous value (P * g) of the input power.} Calculate (P ^* dc). Then, the power command generation unit 520 generates an inverter output power command value (P ^* inv) by ^{using the instantaneous value (P *} g) of the input power and the instantaneous value of the dc stage power (P ^{* dc).} .

Referring to FIG. 9, the system voltage Vg detected by the system voltage detection unit F is applied to the zero crossing detection unit 605 and the phase detection unit (PLL) 607 in the power command generation unit 520. Can be entered.

The zero crossing point detected by the zero crossing detection unit 605 may be input to the torque command generation unit 325 and used.

The phase detection unit (PLL) 607 detects the phase θg using the system voltage Vg detected by the system voltage detection unit F. The detected phase θg is used in the first unit 609.

)를 입력받아, 이를 승산한다. 이에 의해, 입력 전력(P'g)이 연산될 수 있다. 제3 유닛(612)에 입력된다.On the other hand, the second unit 611 has a torque command value (T ^* ) and an operation speed (

) Is input and multiplied by it. Accordingly, the input power P'g can be calculated. It is input to the third unit 612.

The third unit 612 multiplies the calculated input power P'g by the sine wave function 3sin ² (θg) output from the first unit 609. Thereby, the input power instantaneous value (P ^* g) is calculated.

On the other hand, the fourth unit 614, the capacitance of the capacitor (C) (Cdc), the dc terminal voltage, calculated by the dc terminal voltage (Vdc) detected by the dc terminal voltage detector, generates a dc terminal power instantaneous value (P ^* dc) And print it out.

The fifth unit 616 subtracts the dc stage voltage command value (P ^* dc) from the input power instantaneous value (P ^{* g).} Then, the difference between the instantaneous input power (P ^* g) and the instantaneous power of a single dc power (P ^* dc), that is, the inverter output power command value (P ^* inv) is output. The inverter output power command value (P ^* inv) can also be referred to as an inverter power instantaneous value.

Equation 2 below illustrates a method of ^{calculating the inverter output power command value (P *} inv) calculated inside the power command generation unit 520 of FIG. 9 described above.

Here, Vg is the system voltage, Ig is the system current, Vdc is the dc voltage, and Cdc is the capacitance of the capacitor (C). In addition, wgt corresponds to the phase θg described above.

^{The power command value P *} output from the power command generation unit 520 of FIG. 8A and the inverter output power command value P ^* inv of FIG. 9 mean the same value.

Next, the power controller 525 performs power control based on the input inverter output power command value (P ^{* inv).}

The power controller 525 may generate a second voltage command value V ^* ₂ ^{based on the inverter output power command value P *} inv. Here, the second voltage command value (V ^* ₂ ) is a compensation voltage command value for compensating the first voltage command value (V ^* _{1) in which the dc terminal voltage is not considered.}

The adder 555 adds the first voltage command value (V ^* ₁ ) and the second voltage command value (V ^* ₂ ) and outputs it. That is, as the third voltage command value, the inverter output voltage command value (V ^* 3) is output.

Then, the switching control signal output unit 360 generates and outputs a switching control signal based on ^{the third voltage command value (V * 3).}

Meanwhile, the detailed operation of the power controller 525 is as follows.

Meanwhile, the magnitude of the inverter power Pinv may be determined as an inner product of the motor output current vector and the inverter output voltage vector. Accordingly, in order to obtain a desired inverter power, the motor current vector or the inverter output voltage vector can be adjusted.

Among them, the method of adjusting the motor output current vector may not be able to quickly follow the inverter output power command value due to a delay generated by the voltage command generation unit 340. In addition, in a given motor output current situation, in order to match the size of the required inverter output voltage and the size of the inverter power, the size of the required voltage is different, so accurate inverter power control may not be achieved.

Accordingly, in this specification, a method of adjusting the inverter output voltage vector is proposed.

According to an embodiment of the present invention, the power controller 525 generates a second voltage command value (V ^* ₂ ) ^{for compensating the first voltage command value (V *} _{1) in response to the dc terminal voltage.} Accordingly, through the power controller 525, it is possible to control the inverter output voltage.

Since the inverter output voltage vector may affect not only the inverter output power but also the change of the motor current vector, it is necessary to minimize the influence on the voltage command generator 340 by selecting an appropriate voltage vector.

The power controller 525 may select any one of various inverter output voltage command vectors in consideration of the inverter output power command value.

)에 평행하며, 최종 전압 지령치의 벡터(

)가, 제1 전압 지령치의 벡터(

)에 가장 가까운 벡터가 되도록 하는, 벡터를, 보상 전압 지령치의 벡터(

)로 산출할 수 있다. 그리고, 전력 제어기(525)는, 산출된 보상 전압 지령치의 벡터(

)를 제2 전압 지령치의 벡터(

)로 출력할 수 있다.That is, the power controller 525 is the vector of the output current flowing in the motor (

) And the vector of the final voltage setpoint (

) Is the vector of the first voltage command value (

The vector, which makes the vector closest to ), is the vector of the compensation voltage setpoint (

) Can be calculated. Then, the power controller 525 is a vector of the calculated compensation voltage command value (

) Is the vector of the second voltage setpoint (

) Can be printed.

The inverter output voltage vector, that is, the third voltage command value (V ^* 3) may be calculated by the sum of the first voltage command value (V ^* ₁ ) and the second voltage command value (V ^* _{2 ).}

Accordingly, according to an embodiment of the present invention, in order to control output power of a desired inverter, real-time compensation of the output voltage is possible. That is, real-time compensation according to the load becomes possible, and therefore, when the inverter is driven under capacitorless, the system current approaches the sine wave, and the harmonic component is considerably reduced. Therefore, the harmonic regulation is satisfied.

10A illustrates waveforms of a dc voltage and a grid current according to a first mode.

According to the operation of the first mode operation unit 420 of FIG. 8A, as described above, the system current shaping is performed, and thus, as shown in the drawing, the system current Ig_mode1 is corresponding to the dc voltage waveform Vdc_mode1. ) A waveform is formed. Accordingly, harmonics are reduced, and harmonic regulation is also satisfied.

10B illustrates waveforms of a dc voltage and a grid current according to the second mode.

According to the operation of the second mode operation unit 430 of FIG. 8B, as described above, the system current shaping is not performed, and thus, as shown in the figure, the system current does not follow the dc voltage waveform (Vdc_mode2). The (Ig_mode2) waveform is formed. However, since the motor output is less than a predetermined value, the harmonic of the system current is not very large, and instead, the output of the motor is improved.

The electric motor driving apparatus and the air conditioner having the same according to the present invention are not limited to the configuration and method of the embodiments described as described above, but the above embodiments are all of the respective embodiments so that various modifications can be made. Alternatively, some may be selectively combined and configured.

Meanwhile, the method of operating an electric motor driving apparatus or air conditioner according to the present invention may be implemented as a code readable by a processor on a recording medium readable by a processor provided in the electric motor driving apparatus or air conditioner. The processor-readable recording medium includes all types of recording devices that store data that can be read by the processor. Examples of recording media that can be read by the processor include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc., and also include those implemented in the form of carrier waves such as transmission through the Internet. . In addition, the recording medium readable by the processor may be distributed over a computer system connected through a network, so that code readable by the processor may be stored and executed in a distributed manner.

In addition, although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the technical field to which the present invention belongs without departing from the gist of the present invention claimed in the claims. In addition, various modifications are possible by those of ordinary skill in the art, and these modifications should not be understood individually from the technical spirit or prospect of the present invention.

Claims (13)

An inverter having a plurality of switching elements and converting pulsating pulsating power to output the converted DC power to the motor; And
Includes; a control unit for controlling the inverter,
The control unit,
Based on the speed and torque of the motor, controlling to operate in a first mode for performing grid current shaping or a second mode for not performing grid current shaping,
The control unit,
A mode selector for selecting one of the first mode and the second mode based on a speed calculated based on an output current flowing through the motor and a torque command value; And
And a torque command generation unit that generates the torque command value based on the calculated speed and speed command value. The method of claim 1,
The control unit,
When the motor output based on the speed and torque of the motor is greater than or equal to a predetermined value, the first mode is controlled to be performed, and when the motor is less than the predetermined value, the second mode is controlled to be performed. The method of claim 1,
Further comprising a; a rectifier for rectifying the system current,
The control unit,
When the first mode is operated, the system current shaping is performed so that the system current corresponds to the pulsating power. delete delete The method of claim 1,
The control unit,
Further comprising a first mode operation unit for operating the motor in a first mode,
The first mode operation unit,
A current command generation unit that generates a current command value based on the torque command value;
A voltage command generation unit that generates a first voltage command value based on the current command value;
A power command generation unit that generates a power command value based on the torque command value;
A power controller that generates a second voltage command value based on the power command value; And
And a switching control signal output unit configured to output a switching control signal based on the first and second voltage command values. The method of claim 1,
The control unit,
Further comprising a second mode operation unit for operating the motor in a second mode,
The second mode operation unit,
A current command generation unit that generates a current command value based on the torque command value;
A voltage command generation unit that generates a voltage command value based on the current command value; And
And a switching control signal output unit for outputting a switching control signal based on the voltage command value. The method of claim 1,
The motor driving apparatus, characterized in that the efficiency of the motor in the second mode section is greater than that of the motor in the first mode section. A compressor that compresses a refrigerant;
A heat exchanger for performing heat exchange using the compressed refrigerant; And
Including; a compressor motor driving device for driving a motor in the compressor,
The compressor motor driving device,
An inverter having a plurality of switching elements and converting pulsating pulsating power to output the converted DC power to the motor; And
Includes; a control unit for controlling the inverter,
The control unit,
Based on the speed and torque of the motor, controlling to operate in a first mode for performing grid current shaping or a second mode for not performing grid current shaping,
The control unit,
A mode selector for selecting one of the first mode and the second mode based on a speed calculated based on an output current flowing through the motor and a torque command value;
A torque command generation unit that generates the torque command value based on the calculated speed and speed command value;
A first mode operation unit operating the motor in a first mode; And
Includes; a second mode operation unit for operating the motor in a second mode,
The first mode operation unit,
A current command generation unit that generates a current command value based on the torque command value;
A voltage command generation unit that generates a first voltage command value based on the current command value;
A power command generation unit that generates a power command value based on the torque command value;
A power controller that generates a second voltage command value based on the power command value; And
And a switching control signal output unit configured to output a switching control signal based on the first and second voltage command values. The method of claim 9,
The control unit,
When the motor output based on the speed and torque of the motor is greater than or equal to a predetermined value, the first mode is controlled to be performed, and when the motor output is less than the predetermined value, the second mode is controlled to be performed. The method of claim 9,
Further comprising a; a rectifier for rectifying the system current,
The control unit,
When the first mode is operated, the system current shaping is performed so that the system current corresponds to the pulsating power.

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