KR101965737B1 - Apparatus for driving compressor and motor of air conditioner - Google Patents

Abstract

An electric motor drive of an air conditioner is disclosed. The electric motor drive device of the air conditioner according to the present invention eliminates the complicated circuit of directly detecting the input current of the compressor motor and the fan motor motor, and consumes the current flowing to the load of the compressor motor and the fan motor motor of the air conditioner. By estimating the input current of the inverter from the power, a simple circuit implementation can efficiently control the motor of the air conditioner.

Description

Electric motor drive device of air conditioner {APPARATUS FOR DRIVING COMPRESSOR AND MOTOR OF AIR CONDITIONER}

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 estimating an input current of an inverter from power consumption of a motor load.

An air conditioner is a device that is arranged 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. Meanwhile, an electric motor is used for a compressor, a fan, and the like provided in the air conditioner, and the electric motor is driven through a driving device. Inverters are generally used for such a drive.

In general, an inverter is a power conversion device for converting DC power into three-phase AC power (U, V, W) having an arbitrary variable frequency, and is adopted in electrical appliances such as air conditioners for energy saving and ease of output control. Drive the compressor motor and fan motor.

These inverters have a maximum allowable power of the rated voltage and the rated current. If a voltage or a current out of the rated voltage and the rated current is input, the inverter may not operate properly or may cause a failure. Therefore, in order to protect the inverter when a current other than the rated current is input, various devices for measuring the magnitude of the current input to the inverter in real time have been developed. For example, a current transformer (CT) may be used to measure the current input to the inverter. The current converter CT is connected to a commercial input power supply terminal, and the AC signal induced on the secondary side of the current converter CT is rectified by the rectifier through a resistor to measure the input current of the power input to the inverter.

However, since the input current measuring device of such an inverter needs to use a separate current converter to directly detect the current input to the inverter, the manufacturing cost increases, and rectifiers, smoothing capacitors, and the like are used for signal processing of the current detected by the current converter. Since an additional circuit of a low pass filter (LPF) composed of resistors must be provided, the circuit is complicated.

Accordingly, the present invention is to solve the above problems, the object of the present invention is to configure the input current of the inverter from the power consumption consumed in the motor load of the air conditioner, without configuring a separate circuit to detect the input current The present invention provides an electric motor driving apparatus of an air conditioner implemented to estimate and control the operation of the inverter therefrom.

An electric motor driving apparatus of an air conditioner according to an embodiment of the present invention includes a rectifying unit for rectifying an AC voltage of an input power source; A smoothing unit smoothing the rectified AC voltage into a DC voltage; An inverter having a plurality of switching elements and converting the DC voltage into a motor driving voltage and applying the same to a motor according to a control signal; Detects the DC voltage across the smoothing part and the output current flowing between the inverter and the motor, estimates the power consumption flowing in the motor load using the detected DC voltage and the output current, and calculates the inverter from the estimated power consumption. And a controller for estimating an input current of the controller.

The control unit may output a frequency control signal to the inverter unit to control the driving of the motor in response to the estimated input voltage.

In an embodiment, the controller may include a command voltage calculation module configured to calculate a command voltage from the detected DC voltage; A command current calculation module configured to calculate a command current by performing coordinate transformation from the detected output current; And a power consumption estimation module for estimating power consumption flowing in the motor load based on the calculated command voltage and command current.

In an embodiment, the power consumption may be a value obtained by accumulating at least a plurality of times the power consumption flowing in the motor load.

In an embodiment, the power consumption may be estimated by a sum of power consumption of a compressor motor, power consumption of a fan motor, and power consumption of a switching mode power supply divided by power efficiency. do.

In an embodiment, the power consumption of the fan motor is characterized in that the constant value obtained by forcibly stopping the drive of the compressor motor and forcibly driving the fan motor.

In an embodiment, the power consumption of the switched mode power supply (SMPS) is characterized by applying a predetermined constant value.

In an embodiment, the motor driving device may further include a resistor connected between an output end of the smoothing part and an input end of the inverter.

In an embodiment, the motor driving device further comprises a reactor for improving the power factor of the input power.

In an exemplary embodiment, the controller may generate a control signal for switching the switching elements based on the command voltage and the command current.

In an embodiment, the control unit stops generation of a control signal for switching the switching elements when the estimated input current exceeds a preset allowable range.

In an embodiment, the rectifier is formed by connecting two pairs of diodes in parallel, each pair is formed by connecting two diodes in series, and the smoothing part is formed of at least one capacitor.

In addition, the air conditioner according to an embodiment of the present invention is characterized in that to drive the motor of the air conditioner using the above-described motor drive device.

The motor driving apparatus of the air conditioner according to the present invention is based on the power consumption of the inverter from the power consumption flowing through the load of the compressor of the air conditioner and the motor for the fan motor without forming a complicated circuit to detect the input current of the motor in the air conditioner. By estimating the input current, the circuit implementation is simple and the motor of the air conditioner can be efficiently controlled.

In addition, the motor driving apparatus of the air conditioner according to the present invention has an effect of more stable calculation by performing the calculation to estimate the input current from the power consumption of each motor without directly detecting the input current of the motor.

1 is a view showing an example of an air conditioner including an electric motor drive device according to the present invention;
2 is a circuit configuration diagram of a general electric motor drive device;
3 is a circuit diagram of a motor driving apparatus according to the present invention;
Figure 4 is a block diagram showing a process of estimating the inverter input current of the motor drive apparatus according to the present invention;

Hereinafter, a motor driving apparatus of an air conditioner according to an embodiment of the present invention will be described in detail with reference to the drawings.

First, referring to FIG. 3, FIG. 3 shows a circuit configuration of the motor driving apparatus according to the present invention. As shown in the drawing, the motor driving device includes a rectifying unit 200, a smoothing unit 300, an inverter 400, and a control unit 700. In addition, the motor driving device includes an input power source 100 and a resistor 350, and is connected to the compressor motor 500 and / or the fan motor motor 800.

The input power source 100 is a power supply source of the compressor motor 500 and the fan motor 800, and supplies, for example, an AC voltage of 220V and 60Hz.

The rectifier 200 rectifies the AC voltage supplied by the input power supply 100. That is, the rectifier 200 full-wave rectifies the AC voltage supplied by the input power supply 100 through a diode bridge circuit composed of four diodes. In the embodiment, the rectifier 200 is formed by connecting two diodes in parallel with each other, and each pair is connected with two diodes in series. In another embodiment, the rectifier 200 may be formed of a diode bridge circuit including six diodes and switching elements.

The smoothing unit 300 smoothes the rectified AC voltage to a DC voltage. In an embodiment, as illustrated in FIG. 3, the smoothing unit 300 may be formed of at least one DC link capacitor, and may be configured as a simple circuit including the same.

The inverter 400 includes a plurality of switching elements and converts the DC voltage into a motor driving voltage according to a control signal and applies the same to the motor. That is, the inverter 400 performs a pulse width modulation (PWM) on the DC voltage supplied from the smoothing unit 300 according to the control signal of the control unit 700 to generate a three-phase AC voltage having an arbitrary variable frequency ( U, V, and W) are supplied to the compressor motor 500. In this regard, referring to FIG. 3, an electric motor driving apparatus of an air conditioner according to the present invention includes an inverter 400 for providing a three-phase AC voltage to a compressor motor 500, and a fan motor 800. The motor control circuit 600 for providing a three-phase AC voltage is provided separately. In addition, the switching elements of the inverter 400, a pair of phase arm switching element and the lower arm switching element connected to each other forms a pair, a total of three pairs of the upper and lower arm switching elements constitute a circuit connected in parallel. In addition, the motor control circuit 600 may be implemented in a circuit configuration similar to the inverter 400.

The control unit 700 detects a DC voltage applied to both ends of the smoothing unit 300. In addition, the controller 700 detects an output current flowing between the inverter 400 and the motor 500 through, for example, a shunt resistor 350. In addition, the controller 700 estimates power consumption flowing to the motor load by using the detected DC voltage and output current. The controller 700 may estimate the input current of the inverter 400 from the estimated power consumption. In addition, the control unit 700 outputs a frequency control signal to the inverter unit 400 to control the driving of the motor 500 in response to the estimated input current. Here, the frequency control signal refers to a general scheme according to a pulse width modulation (PWM) control signal, a detailed description thereof will be omitted.

The controller 700 estimates power consumption flowing to the motor load by using the detected DC voltage and output current. In an embodiment, the controller 700 may include a command voltage calculation module that calculates a command voltage from the detected DC voltage, a command current calculation module that calculates a command current by performing coordinate transformation from the detected output current, and the calculation. It may further include a power consumption estimation module for estimating the power consumption flowing in the motor load based on the command voltage and the command current. Here, the command current calculating module calculates the current command values I _{d and} I _q from the rotation speed and the rotation speed command value of the motor estimated based on the detected output current. The command voltage calculation module calculates the voltage command values V _d and V _q based on the detected DC voltage and the calculated current command values I _{d and} I _q . The power consumption estimation module estimates power consumption flowing to the motor through the following equation (1) using the current command value and the voltage command value. Here, power loss of the diodes of the rectifier 200 is ignored.

Power consumption of the motor (W) = V _d * I _{d ,} + V _q * I _q (1)

To this end, the motor driving apparatus according to the present invention is a means for detecting a DC voltage across the smoothing unit 300, and a means for detecting an output current flowing between the inverter 400 and the motor 500, for example For example, the shunt resistor 350 may be provided. Although not shown, the motor driving apparatus further includes means for converting the detected output current into d-axis and q-axis currents, or converting the d-axis and q-axis currents into an output current flowing between the inverter and the motor. can do.

In an embodiment, the power consumption of the electric motor is characterized by using a value obtained by averaging at least a plurality of times the power consumption flowing in the motor load. For example, a value obtained by accumulating 1000 times the average power consumption flowing through the imaginary motor load may be used as the power consumption value of the compressor motor. As a result, a more reliable power consumption estimate can be obtained.

In an embodiment, the controller 700 generates a control signal for switching the switching elements of the inverter 400 based on the command voltage and the command current. In this case, for example, when the inverter input current estimated based on the command voltage and the command current exceeds a predetermined allowable range, the controller 700 may be configured to include the compressor motor 500 and the fan motor 800. Switch the switching elements of the corresponding inverters 400 and 600 to limit the operation.

On the other hand, referring to Figure 4, Figure 4 shows a process of estimating the input current of the inverter side of the motor drive apparatus using the power consumption flowing in the motor through a block diagram. More specifically, the controller 700 estimates the power consumption of the compressor motor 500 through Equation (1) using the command voltage and the command current. In addition, the controller 700 stops the driving of the compressor motor 500 and forcibly drives only the fan motor 800 of the air conditioner to estimate the power consumption of the fan motor 800. In addition, the controller 700 may estimate power consumption of a switching mode power supply (SMPS). In an embodiment, the power consumption of the switching mode power supply (SMPS) is a predetermined constant value, the constant value may be a power value consumed in the diode device and the switching device provided in the rectifier. Then, the control unit 700, as shown, the sum of the power consumption of the compressor motor, the motor for the fan motor, and the switching mode power supply (SMPS) and divided by the power efficiency, the total consumption of the motor drive device Estimate the power (W). Then, the control unit 700 may estimate the input current applied to the inverter 400 from the total power consumption (W). At this time, if the estimated input current value exceeds the maximum allowable power value of the predetermined rated current, the control unit 700 outputs a control signal for stopping the drive of the inverter to control the drive of the inverter. That is, when the estimated input rectification exceeds the preset allowable range, the controller 700 stops generating the control signal for switching the switching elements of the inverter.

Thus, in the embodiment according to the present invention, the estimation of the total power consumption is based on the sum of the power consumption of the compressor motor, the power consumption of the motor for the fan motor, and the power consumption of the switching mode power supply (SMPS). It can be obtained by dividing by the power efficiency. Here, the switching mode power supply (SMPS) has a reference power value of a predetermined size.

In an embodiment, the motor driving apparatus includes a shunt resistor 350 connected in series between an output terminal of the smoothing unit 300 and an input terminal of the inverter 400. The shunt resistor 350 is used as a means for detecting or estimating the output current flowing between the inverter and the motor.

In an embodiment, the electric motor driving device may include a reactor (not shown) for improving the power factor of the input power source 100. For example, the reactor may be connected in series with the output side of the rectifier 200 to improve the power factor of the rectified AC voltage.

2 shows a circuit diagram of a general motor driving apparatus. This motor driving device is described in comparison with the configuration and operation of the motor driving device according to the present invention. First, a schematic circuit configuration of the general motor driving apparatus shown in FIG. 2 includes an input power source, a rectifying unit, a smoothing unit, an inverter, and a controller (MCU) for outputting a pulse width modulation (PWM) control signal for driving the inverter. It is done by In this case, the motor driving apparatus of FIG. 2 further includes a current transformer CT connected in series between the input power and the rectifier. The current converter CT induces the primary current signal of the input power supply to the secondary side of the current converter CT, rectifies the induced AC signal, and directly measures the input current applied to the inverter. As such, when directly measuring the input current input to the inverter from the current signal provided by the current converter CT, the circuit configuration is complicated and the manufacturing cost of the device increases. On the other hand, in the case of the motor driving apparatus according to the present invention shown in Figure 3 omits the current converter (CT) for directly detecting the current of the input power, all of the calculation logic for estimating the input current of the inverter control unit 700 ( MCU). A detailed operation of the calculation logic in the controller 700 has been described in detail above.

1 shows an example of an air conditioner including the above-described electric motor driving device. Air conditioners are classified into indoor and outdoor units. Referring to FIG. 1, an air conditioner including an electric motor driving apparatus according to the present invention may include one or more indoor units performing air conditioning, an outdoor unit connected to the indoor unit through a pipe, and driving the indoor unit, and a refrigerant at a high temperature. And a compressor for compressing the high pressure, an electric motor for driving the compressor, and a driving device for controlling the driving of the electric motor. The air conditioner may further include a fan motor provided in an outdoor unit to promote heat dissipation of the refrigerant, an electric motor for driving the fan motor, and a driving device for controlling the driving thereof.

Referring to FIG. 1, the outdoor unit 10 includes an evaporator 13 for exchanging heat by exchanging the refrigerant compressed by the compressor with air, and an expansion valve for expanding the refrigerant radiated from the evaporator at low temperature and low pressure. 14, a condenser 15 for exchanging the low-temperature and low-pressure refrigerant with water, a compressor 12 for compressing the refrigerant, and an outlet of the compressor 12 for storing the compressed refrigerant. It further comprises a refrigerant switching valve 17 for guiding the evaporator 13 or the condenser 15.

As shown in FIG. 1, the outdoor unit 10 includes a refrigeration cycle including a compressor 12, an evaporator 13, an expansion valve 14, and a condenser 15 inside the case 11. A plurality of fans 16 are installed on the upper surface or the side surface of the case 11 to intake external air to exchange heat with the evaporator 13, and the condenser 15 may be cold or hot water with indoor units 20. Medium circulation pipe 30 for supplying is connected. At the outlet of the compressor 12, a refrigerant switching valve 17 for converting the refrigerant compressed by the compressor 12 in the evaporator direction or the condenser direction according to the operating conditions is installed. The refrigerant switching valve 17 is usually composed of a four-way valve. The outdoor unit 10 as described above is operated by switching to a heater in winter while operating as a cooler in summer. For example, in the summer, the refrigerant is compressed at high temperature and high pressure in the compressor 12, the refrigerant switching valve is guided to the evaporator 13, the heat exchanged with the air in the evaporator 13, heat dissipation, and the low temperature, After making low pressure and heat exchange with the water in the condenser 15, the heat exchanged water is supplied to the indoor units 20 used as a cooling heat source. On the other hand, during the winter, the refrigerant switching valve 17 guides the refrigerant toward the condenser, so that high-temperature and high-pressure refrigerant is exchanged with water in the condenser 15 to the indoor units 20 using the heat-exchanged water as a heating heat source. Supply. On the other hand, in the air conditioner according to the present invention, the electric motor of the motor drive device may be an electric motor for driving the compressor, the outdoor fan, and the indoor fan motor of the air conditioner.

As described above, the air conditioner including the electric motor driving device according to the present invention implements the electric motor driving device so that the input current of the inverter can be estimated from the power consumption flowing in the load of the electric motor, thereby the inverter motor of the compressor motor or the fan motor motor. By omitting the apparatus for directly detecting the side input current, the circuit configuration is simple and the manufacturing cost is reduced.

As described above, the motor driving apparatus of the air conditioner according to the embodiment of the present invention, without a complicated circuit for detecting the input current of the motor in the air conditioner, air conditioning through the calculation logic performed in the control unit By estimating the power consumption flowing through the load of the compressor and the motor for the fan motor, and estimating the input current of the inverter from this, the circuit configuration can be simplified and the motors of the compressor and the fan motor can be efficiently controlled.

100-Input Power 200-Rectifier
300-Smoothing 350-Shunt Resistance
400-Inverter 500-Compressor Motor
600-Motor Control Circuit 700-Control Unit
800-electric motor for fan motor

Claims (12)

Rectifier for rectifying the AC voltage of the input power source;
A smoothing unit for smoothing the rectified AC voltage to a DC voltage;
An inverter having a plurality of switching elements and converting the DC voltage into a motor driving voltage for a compressor according to a control signal and applying the same to the compressor motor;
A motor control circuit having a plurality of switching elements and converting the DC voltage into a motor driving voltage for a fan motor according to a control signal and applying the same to the fan motor motor;
A resistor connected between the output terminal of the smoothing unit and the input terminal of the inverter; And
The output current flowing between the inverter and the compressor motor and the output current flowing between the motor control circuit and the fan motor are detected by using the DC voltages of the both ends of the smoothing part and the resistance, and the detected DC voltage and output And a controller for estimating power consumption at the load of the compressor motor and the motor of the fan motor using current, and estimating input currents of the inverter and the motor control circuit from the estimated power consumption. Electric motor drive of air conditioner. According to claim 1,
And the control unit outputs a frequency control signal to the inverter so that driving of the compressor motor and the fan motor motor is controlled in response to the estimated input current. According to claim 1,
The control unit,
A command voltage calculation module for calculating a command voltage from the detected DC voltage; A command current calculation module configured to calculate a command current by performing coordinate transformation from the detected output current; And a power consumption estimation module for estimating power consumption flowing to the compressor motor and the fan motor motor load based on the calculated command voltage and the command current. According to claim 1,
And the power consumption is a value obtained by averaging at least a plurality of times the power consumption flowing in the compressor motor and the fan motor motor load. According to claim 1,
The power consumption is estimated by a sum of power consumption of a compressor motor, power consumption of a fan motor, and power consumption of a switching mode power supply (SMPS) divided by power efficiency. Electric motor drive of the machine. The method of claim 5,
The power consumption of the electric motor for the fan motor is a constant value obtained by forcibly driving the electric motor for the fan motor. delete According to claim 1,
And a reactor for improving the power factor of the input power source. The method of claim 3, wherein
The control unit,
And a control signal for switching the switching elements on the basis of the command voltage and the command current. According to claim 1,
The control unit,
And stopping the generation of a control signal for switching the switching elements when the estimated input voltage exceeds a preset allowable range. According to claim 1,
The rectifying unit, two pairs of diodes are connected in parallel, each pair is formed by connecting two diodes in series,
The smoothing unit, the motor drive device of the air conditioner, characterized in that consisting of at least one capacitor. An air conditioner, characterized in that for driving an electric motor of an air conditioner using the electric motor drive device according to any one of claims 1 to 6 and 8 to 11.

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