KR20200046848A - Motor Driving Apparatus and Air conditioner - Google Patents

Abstract

The present invention relates to a motor drive device and an air conditioner, a rectifier rectifying the input AC power, a boost converter disposed between the DC terminal capacitors and boosting and outputting the rectified power from the rectifier, while the boost converter is not operating , By including a compensation unit rectifying the input AC power and applying it to the DC terminal capacitor, the current flow is changed in a low load section in which the boost converter does not operate, preventing loss due to conduction, and using a potential difference to separate By changing the current flow without a switch, it is possible to improve the efficiency according to the motor operation.

Description

Motor Driving Apparatus and Air conditioner

The present invention relates to a motor drive device and an air conditioner, and more particularly to a motor drive device and an air conditioner for controlling the operation of a compressor or fan, including a motor drive device using a low-capacity capacitor.

The air conditioner is installed to provide a more comfortable indoor environment by discharging cold and hot air into the room to create a comfortable indoor environment, adjusting the indoor temperature, and purifying the indoor air.

The air conditioner is controlled by an indoor unit composed of a heat exchanger, and an outdoor unit composed of a compressor and a heat exchanger, and the outdoor unit and the indoor unit are connected by a refrigerant pipe, and refrigerant compressed from the compressor of the outdoor unit is supplied to the heat exchanger of the indoor unit through the refrigerant pipe, The refrigerant exchanged in the heat exchanger of the indoor unit flows back into the compressor of the outdoor unit through the refrigerant pipe. Accordingly, the indoor unit discharges cold and hot air into the room through heat exchange using a refrigerant.

The compressor or fan is operated by driving the motor. Accordingly, development is being conducted to operate the motor more effectively. As the use of the inverter type compressor and fan increases, various methods for controlling the motor are applied. Particularly, PFC (Power Factor Correction) is increasingly used to improve switching efficiency for driving a motor.

Korean Patent Registration No. 10-1161981 (2012.7.3) discloses a motor driving device. Disclosed is a boost converter that reduces the breakdown voltage of each element provided in a circuit configuration for driving a motor and reduces the breakdown voltage by a voltage applied to a diode. However, there is an advantage of reducing the breakdown voltage of the device, but its use is limited due to a structure suitable for a small-capacity capacitor.

Therefore, in the case of PFC (Power Factor Correction) generally used for driving a motor, it is configured to operate only in some sections and not to switch in some sections due to its efficiency problem. Accordingly, there is a need to improve the efficiency in the low load section while using PFC.

An object of the present invention is a motor driving device and an air conditioner, a motor driving device capable of stably driving a compressor motor and a fan motor based on input AC power in a motor driving device using a low-capacity capacitor and air having the same In providing a harmony.

The motor driving apparatus according to the present invention includes a rectifying unit rectifying an input AC power; A DC stage capacitor storing pulsating voltage from the rectifying unit; A boost converter disposed between the rectifying unit and the DC terminal capacitor, and boosting and outputting power rectified from the rectifying unit; A compensation unit for rectifying the input AC power and applying it to the DC terminal capacitor while the boost converter is not operating; And an inverter having a plurality of switching elements and outputting the converted AC power to the motor by using voltages at both ends of the DC terminal capacitor.

The compensation unit may include a first diode and a second diode that apply the input AC power to the DC terminal capacitor.

The first diode is conductive when the input voltage is positive, and the second diode is conductive when the input voltage is negative.

The compensating part is characterized by forming a diode bridge circuit together with the first and second diodes by sharing the two bottom diodes of the diode bridge circuit of the rectifying part.

The air conditioner according to the present invention includes a motor provided in a compressor or a fan; A motor driving device that controls the operation of the motor and supplies operating power, and includes a rectifying unit that rectifies an input AC power; A DC stage capacitor storing pulsating voltage from the rectifying unit; A boost converter disposed between the rectifying unit and the DC terminal capacitor, and boosting and outputting power rectified from the rectifying unit; A compensation unit for rectifying the input AC power and applying it to the DC terminal capacitor while the boost converter is not operating; And an inverter that includes a plurality of switching elements and outputs the converted AC power to the motor using voltages at both ends of the DC terminal capacitor.

The motor driving device and the air conditioner according to the present invention configured as described above can drive the compressor motor and the fan motor while minimizing losses due to whether the boost converter is operated.

The present invention, by changing the flow of current in the low load section in which the boost converter does not operate, can prevent loss due to conduction, and improve the efficiency according to the motor operation.

The present invention can improve efficiency by simple structure change through the addition of a diode. In addition, the present invention can change the flow of current without a separate switch using a potential difference.

1 is a schematic diagram of an outdoor unit and an indoor unit of an air conditioner according to an embodiment of the present invention.
FIG. 2 is a block diagram of a motor driving device in the outdoor unit of FIG. 1.
3 is a circuit diagram of a motor drive device of an air conditioner according to an embodiment of the present invention.
4 and 5 are views referred to for explaining the operation of the motor drive of FIG. 3.
6 is a diagram illustrating a signal change according to a switch operation in a motor driving device of an air conditioner according to an embodiment of the present invention.
7 is a view showing a signal change while the switch is not operating in the motor drive device of the air conditioner according to an embodiment of the present invention.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains It is provided to completely inform the person having the scope of the invention, and the present invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification. In addition, the present invention specifies that the configuration of the control unit and other parts included in the air conditioner may be implemented by one or more processors (Micro Processor), and may be implemented by a hardware device.

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

1 is a schematic diagram of an outdoor unit and an indoor unit 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 any one of a stand type air conditioner, a wall-mounted air conditioner, and a ceiling type air conditioner, but the drawing illustrates the stand type indoor unit 31.

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 supplies a refrigerant to the indoor unit 31 by compressing or heat-exchanging the refrigerant according to a setting by operating a provided compressor and an outdoor heat exchanger. The outdoor unit 21 may be driven by a remote controller (not shown) or a demand of the indoor unit 31. At this time, as the cooling / heating capacity is changed corresponding to the driven indoor unit, it is possible that the number of operation of the outdoor unit and the number of operation of the compressor installed in the outdoor unit are variable.

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

The indoor unit (31) receives refrigerant from the outdoor unit (21) and discharges cold and warm air into the room.

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

The remote control (not shown) is connected to the indoor unit 31, inputs a user's control command to the indoor unit, and receives and displays status information of the indoor unit. At this time, the remote control may communicate with wired or wireless depending on the type of connection with the indoor unit.

The outdoor unit 21 includes a compressor 102 serving to compress refrigerant, an electric motor 102b for driving the compressor, an outdoor heat exchanger 104 serving to dissipate the compressed refrigerant, and outdoor An outdoor blower 105, which is disposed on one side of the heat exchanger 104 to promote heat dissipation of the refrigerant, and an outdoor fan 105 made of an electric fan 105b that rotates the outdoor fan 105a, and expands to expand condensed refrigerant. Mechanism 106, a cooling / heating switching valve 110 that changes the flow path of the compressed refrigerant, and an accumulator 103 that temporarily stores the vaporized refrigerant to remove moisture and foreign substances, and then supplies the refrigerant at a constant pressure to the compressor. And the like.

The indoor unit 31 is disposed indoors to perform an air / heating function, and the indoor heat exchanger 108 and an indoor fan 109a disposed on one side of the indoor heat exchanger 108 to promote heat dissipation of the refrigerant and the indoor And an indoor blower 109 made of an electric motor 109b for rotating the fan 109a.

At least one indoor heat exchanger 108 may be installed. The compressor 102 may be at least one of an inverter compressor and a constant speed compressor.

In addition, the air conditioner 100 may be configured with 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 motor driving device that drives the compressor motor 250. In addition, the indoor fan or the outdoor fan may be driven by a motor connected to the motor.

FIG. 2 is a circuit diagram showing a schematic configuration of the outdoor unit of FIG. 1.

2, the outdoor unit 21 includes a motor driving device (not shown) for driving the motor of the compressor.

The motor driving apparatus includes an inverter (not shown) that outputs a three-phase AC current to the compressor motor 102b, an inverter control unit (not shown) that controls the inverter, and a converter 210 and a converter (which supplies DC power to the inverter). It may include a converter control unit (not shown) for controlling the 210, the DC link terminal 240 between the converter 210 and the inverter.

In addition, the outdoor unit may include an input current detector 131 for detecting an input voltage, a converter current detector 132, and a voltage detector 235 of the converter.

This configuration can be equally applied to a motor driving device for driving a motor provided in the outdoor fan and the indoor fan of the indoor unit 31.

The motor drive device receives AC power from the system, converts the power, and supplies the converted power to the motor. Accordingly, the motor driving device can also be referred to as a power conversion device.

In some cases, the motor driving apparatus according to the embodiment of the present invention may use a dc terminal capacitor C having a low capacity of several tens of μF or less. For example, the low-capacity dc terminal capacitor C may include a film capacitor, not an electrolytic capacitor.

When a low-capacity capacitor is used, a change in the dc stage voltage becomes large, pulsating, and a smoothing operation is rarely performed. Such a motor driving device having a low-capacity dc terminal capacitor (C) (C11) of several tens of μF or less may be referred to as a capacitorless motor driving device.

The converter 210 converts the input AC power to DC power. The converter 210 may be a concept including a rectifier 410 and a boost converter 420.

The converter control unit 215 may control the turn-on timing of the switching element S inside the converter 210. Accordingly, the converter switching control signal Scc for the turn-on timing of the switching element S can be output.

To this end, the converter controller 215 may receive the input voltage Vs and the input current Is from the input voltage detector A and the input current detector B, respectively.

The input voltage detector A can detect the input voltage Vs from the input AC power supply 201. For example, it may be located at the front end of the rectifier 410.

The input voltage detector A may include a resistance element, an OP AMP, and the like for voltage detection. The detected input voltage Vs is a discrete signal in the form of a pulse, and may be applied to the converter control unit 215 for generating the converter switching control signal Scc.

On the other hand, the zero crossing point of the input voltage can also be detected by the input voltage detector A.

Next, the input current detection unit D can detect the input current Is from the input AC power supply 201. Specifically, it may be located at the front end of the rectifier 410.

The input current detector D may include a current sensor, a current trnasformer (CT), and a shunt resistor for current detection. The detected input current Is is a discrete signal in the form of a pulse, and may be applied to the converter control unit 215 to generate the converter switching control signal Scc.

The dc voltage detector (B) detects the pulsating voltage (Vdc) of the dc stage capacitor (C) (C11). For power detection, a resistive element, OP AMP, or the like can be used. The detected voltage of the DC stage capacitor (C) (Vdc), as a discrete signal (discrete signal) in the form of a pulse, can be applied to the inverter control unit 230, the DC voltage of the DC stage capacitor (C) (C11) Vdc), an inverter switching control signal Sic may be generated.

On the other hand, unlike the drawing, the detected dc voltage is applied to the converter control unit 215, the converter switching control signal (Scc) may be used for generation.

The inverter 220 may include a plurality of inverter switching elements, convert DC power smoothed by the on / off operation of the switching elements into three-phase AC power of a predetermined frequency, and output the three-phase motor 250.

Specifically, the inverter 220 may include a plurality of switching elements. For example, the upper arm switching elements S1a, S2a, and S3a and the lower arm switching elements S1b, S2b, and S3b, which are connected to each other in series, are paired, and a total of three pairs of upper and lower arm switching elements can be connected in parallel to each other. have. Further, diodes may be connected in reverse parallel to each of the switching elements (S1a, S2a, S3a, S1b, S2b, and S3b).

In order to control the switching operation of the inverter 220, the inverter control unit 230 may output an inverter switching control signal Sic to the inverter 220. The inverter switching control signal Sic is a switching control signal of a pulse width modulation method (PWM), and is generated based on an output current (i _o ) flowing through the motor 250 and a dc stage voltage (Vdc) across the dc stage capacitor. Can be output. At this time, the output current i _o may be detected from the output current detector E, and the dc stage voltage Vdc may be detected from the dc stage voltage detector B.

The output current detector E can detect the output current i _o flowing between the inverter 220 and the motor 250. That is, the current flowing through the motor 250 is detected. The output current detector E can detect all the output currents ia, ib, and ic of each phase, or may detect the output currents of two phases by using three-phase balance.

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

The inverter control unit 230 includes an axis conversion unit (not shown), a speed calculation unit (not shown), a current command generation unit (not shown), a voltage command generation unit (not shown), an axis conversion unit (not shown), and switching It may include a control signal output unit (not shown). Hereinafter, description of the inverter control unit will be omitted.

3 is a circuit diagram of a motor drive device of an air conditioner according to an embodiment of the present invention.

As shown in FIG. 3, the converter 210 may be a concept including a rectifier 410 and a boost converter 420. In addition, the converter 210 includes a compensation unit 430 connected to the DC terminal capacitor from the current unit.

The rectifying unit 410 receives the power 201 and power, and rectifies the power to output the rectified power.

To this end, the rectifying unit 410, the upper arm diode element and the lower arm diode element, and the 11th to 14th diodes D11 to D14 are connected in series with each other, and a total of two pairs of upper and lower arm diode elements are mutually connected. Illustrates being connected in parallel. That is, they can be connected to each other in the form of a bridge.

The boost converter 420 is between the rectifier 410 and the inverter 220, between the reactor (inductor, L11) and the seventh diode (D17), the reactor (L11) and the seventh diode (D17) connected in series with each other. And a switching element (S) to be connected. The seventh diode is a fast recovery diode (FRD), which is used for high-frequency rectification due to short reverse recovery time and high breakdown voltage.

When the switching element S is turned on, energy is stored in the reactor L11, and when the switching element S is turned off, energy stored in the reactor L11 is output through the seventh diode D17. You can.

Particularly, in a motor driving apparatus using a low-capacity dc stage capacitor (C) (C11), a voltage of which a constant voltage is boosted, that is, offset, may be output from the boost converter 420.

At this time, the boost converter does not perform the switching operation because the boosting effect is low in the low load section.

The compensation unit 430 includes a first diode D1 connected between the eleventh diode D11 and the twelfth diode D12 of the rectifying unit 410 and connected to the power source 201. In addition, the compensation unit 430 includes a second diode D2 connected between the thirteenth diode D13 and the fourteenth diode D14 of the rectifying unit 410 and to the other end of the power supply 201. The cathode of the first diode D1 and the second diode D2 is connected to the DC terminal capacitor C11.

The compensator 430 shares the twelfth diode D12 and the fourteenth diode D14 of the rectifier 410.

When the boost converter 420 does not operate, as the current flows through the first diode or the second diode due to the low load, the 12th, 14th, 1st, and 2nd diodes operate as a rectifier, so that the rectifier 410 Share a diode.

In this case, the case where the boost converter does not operate means that the switching element does not perform the switching operation. This does not mean that the switching element is OFF, but that the switching element does not perform the switching operation.

When the boost converter 420 operates, a current flows to the reactor L11 with a high total position. At this time, the boost converter 420 flows through the reactor L11 and the seventh diode D17 and the switching element S, and the DC terminal capacitor according to the ON and OFF of the switching element S ( C11) is controlled.

Meanwhile, when the boost converter 420 does not operate, that is, when switching is not performed, current flows in a direction in which the load is low. Accordingly, a current flows from the power supply to the DC terminal capacitor C11 through the first diode D1 or the second diode D2.

If the current flows through the rectifier, the reactor, and the seventh diode D17 while the boost converter is not operating, since it does not operate as a converter, current loss occurs in each device.

On the other hand, when the compensation unit is provided, while the boost converter is not operating, it flows to the first or second diodes D1 and D2 and is applied directly to the DC terminal capacitor, thereby causing the rectifier, reactor, and seventh diode D17. Loss is reduced.

4 and 5 are views referred to for explaining the operation of the motor drive of FIG. 3.

When the boost converter does not operate, as shown in FIGS. 4A and 4B, the current flows through the compensation unit 430 to the DC terminal capacitor C11.

When the boost converter is operated, current flows through the boost converter 420, as shown in FIGS. 5A and 5B.

4 (a) and 5 (a) are current flows when the input voltage is positive (+), and the input voltage is negative (-) in FIGS. 4 (b) and 5 (b). ).

When the boost converter does not operate, the low-capacity dc stage capacitor C is connected to the compensation unit 430 without the boost converter 420, and the compensation unit shares a part of the diode of the rectification unit and operates as a rectification unit.

4 (a), when the input voltage is positive (+), current flows from the power supply 201 through the first diode D1 to the DC terminal capacitor C11. In addition, the DC terminal capacitor C11 is connected to the 14th diode D14 to form a loop connected to the power source 201.

When the input voltage is negative (-), as shown in (b) of FIG. 4, the current flows from the power supply 201 through the second diode D2 to the DC terminal capacitor C11. In addition, the DC terminal capacitor C11 is connected to the twelfth diode D12 to form a loop connected to the power source 201.

At this time, since the current flows through the DC terminal capacitor without going through the reactor of the boost converter and the seventh diode D17, loss is reduced.

On the other hand, when the boost converter is operating, as shown in (a) of FIG. 5, if the input voltage is positive (+), the current flows from the power source 201 through the eleventh diode D11 of the rectifier, the reactor L11, the 7 A current flows through the diode D17 and the switching element S to the DC terminal capacitor C11. In addition, it is connected to the power source through the 14th diode D14 of the rectifying unit.

When the input voltage is negative (-), as shown in Fig. 5 (b), the current flows through the 13th diode D13 to the reactor L11, the 7th diode D17 and the switching element S Current flows through the DC stage capacitor (C11). In addition, it is connected to the power source through the twelfth diode (D12) of the rectifying unit.

 6 is a diagram illustrating a signal change according to a switch operation in a motor driving device of an air conditioner according to an embodiment of the present invention, and FIG. 7 is a motor driving device of an air conditioner according to an embodiment of the present invention This is a diagram showing a signal change while the switch is not operating.

4 (a) and 4 (b) described above, when the boost converter is not operated, voltages and currents are formed in each part of the motor drive device as shown in FIG. 6.

6 and 7 (a) is the voltage (S1) (S11) of the DC stage, (b) is the input current (S2) (S12), (c) is the current flowing through the compensation unit (S3) (S13) ) and (d) are currents S4 and S14 flowing through the reactor L11.

In addition, as shown in Fig. 6A, the voltage S1 of the capacitor C11 of the DC terminal has a small capacitor, so that a voltage is formed similar to the input voltage. On the other hand, as shown in (a) of FIG. 7, the voltage S11 of the capacitor C11 of the DC stage is boosted by the operation of the boost converter to form a high voltage. Due to the boosting effect by switching, the voltage rises compared to FIG. 6.

Since the boost converter does not operate initially, a current flows through the compensator due to the potential difference. At this time, the capacitor C11 of the DC stage is charged by the current S3 supplied from the compensation unit.

On the other hand, when the boost converter starts switching, since the potential of the reactor is low, the potential difference is low or the same, and the current S14 flows through the rectifier and the reactor.

Therefore, when the boost converter does not operate, as shown in (c) and (d) of FIG. 6, the current S3 flows to the compensation unit 430, and the current S4 of the reactor L11 becomes zero.

On the other hand, when the boost converter is in the switching operation, as shown in (c) and (d) of FIG. 7, since the current does not flow to the compensation unit 430, the current S13 becomes 0, and the current S14 flows to the reactor. .

Accordingly, the present invention can further improve the efficiency of driving the motor by simply preventing the loss that occurs when the boost converter is not operated by additionally configuring the diode. In addition, the current flow may be changed without a separate switch as the current flow is changed by the potential difference in the circuit.

Although all components constituting the embodiments of the present invention have been described as being combined and operated, the present invention is not necessarily limited to these embodiments. If within the scope of the object of the present invention, depending on the embodiment, all the components may be operated by selectively combining one or more.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention.

21: outdoor unit 31: indoor unit
102: compressor 102b: compressor motor
105: outdoor fan 108: indoor fan
210: converter 220: inverter
250: motor
410: rectifier 420: boost converter
430: compensation unit

Claims (12)

A rectifying unit rectifying the input AC power;
A DC stage capacitor storing pulsating voltage from the rectifying unit;
A boost converter disposed between the rectifying unit and the DC terminal capacitor, and boosting and outputting power rectified from the rectifying unit;
A compensation unit for rectifying the input AC power and applying it to the DC terminal capacitor while the boost converter is not operating; And
A motor driving apparatus including a plurality of switching elements and an inverter that outputs the converted AC power to the motor by using voltages at both ends of the DC terminal capacitor. According to claim 1,
The compensator comprises a first diode and a second diode for applying the input AC power to the DC terminal capacitor. According to claim 2,
The first diode is conductive when the input voltage is positive,
A motor driving device for conducting the second diode when the input voltage is negative. According to claim 2,
A motor driving device, characterized in that one end is connected between the first diode and the second diode between the input AC power and the rectifier, and the other end is connected to the DC terminal capacitor. According to claim 2,
The rectifying unit includes 11 to 14 diodes,
The first diode has one end connected to the eleventh diode and the input AC power supply, and the other end is connected to the DC terminal capacitor,
The second diode is a motor driving device, characterized in that one end is connected to the thirteenth diode and the input AC power and the other end is connected to the DC terminal capacitor. According to claim 2,
And the compensating part shares two bottom diodes of the diode bridge circuit of the rectifying part to form a diode bridge circuit together with the first and second diodes. According to claim 1,
The compensation unit, while the boost converter is not operating, the motor drive device, characterized in that applying the current from the input AC power to the DC terminal capacitor. According to claim 1,
While the boost converter is operating, a motor driving device characterized in that a current is applied to the DC terminal capacitor by a potential difference between the compensation units. According to claim 1,
The DC stage capacitor
When the boost converter is operating, a voltage boosted through the boost converter is applied,
When the boost converter does not operate, the motor drive device characterized in that the input power is applied through the compensation unit. According to claim 1,
The boost converter includes a reactor connected to the rectifier, a third diode, and a switching element,
The compensation unit is a motor drive device, characterized in that the current from the input AC power is applied according to the potential difference with the reactor. According to claim 1,
The DC stage capacitor is a motor driving device, characterized in that the low-capacity capacitor of n microfarad. A motor provided in the compressor or fan;
Includes; a motor driving device for controlling the operation of the motor, and supplies the operation power;
The motor drive,
A rectifying unit rectifying the input AC power;
A DC stage capacitor storing pulsating voltage from the rectifying unit;
A boost converter disposed between the rectifying unit and the DC terminal capacitor, and boosting and outputting power rectified from the rectifying unit;
A compensation unit for rectifying the input AC power and applying it to the DC terminal capacitor while the boost converter is not operating; And
An air conditioner comprising a plurality of switching elements and an inverter that outputs the converted AC power to the motor by using voltages at both ends of the DC terminal capacitor.

Images