KR20180098940A - Power supply apparatus for air conditioner - Google Patents

Abstract

The present invention relates to an air conditioner, and more particularly, to a power supply device of an air conditioner, capable of preventing a burnout due to lightning and an electric shock. The power supply device of an air conditioner according to the present invention includes: a sensing unit connected to a ground connection unit on an AC power source side to sense a current; a power converting unit connected to the AC power source and including an inverter for driving a motor; and an inverter control unit connected to the sensing unit and determining whether to drive the inverter according to a voltage sensed in the sensing unit.

Description

[0001] The present invention relates to a power supply apparatus for an air conditioner,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner, and more particularly, to a power unit of an air conditioner capable of preventing electric shock and lightning.

Generally, a compressor of an air conditioner uses a motor as a driving source. These motors are supplied with AC power from a power conversion device.

Such a power conversion apparatus is generally known to include a rectifying section, a power factor control section, and an inverter.

First, the commercial voltage of the AC output from the commercial power source is rectified by the rectifying part. The rectified voltage at this rectifying part is supplied to the inverter. At this time, the inverter generates AC power for driving the motor by using the voltage outputted from the rectifying section.

In some cases, a DC-DC converter for improving the power factor may be provided between the rectification part and the inverter.

Most appliances, including air conditioners, are designed to connect the ground connection to the ground wire at the time of installation to reduce the risk of electric shock to the user due to leakage current. Especially in the case of air conditioners, it is possible to connect the ground to the surface of the product (where human hands can reach) when the appliance is installed.

However, the presence or absence of the ground connection does not affect the operation of the air conditioner, so it may happen that the ground wire is not connected to the ground connection at the time of installation of the apparatus. In this case, if the human body touches the air conditioner during abnormal operation of the equipment, it may lead to electric shock accident due to leakage current.

Therefore, a configuration against such a situation is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power supply unit of an air conditioner capable of preventing an electric shock accident that may occur due to no connection of a ground wire.

Also, it is an object of the present invention to provide an air conditioner power supply device capable of protecting an air conditioner when a surge current due to a lightning stroke is applied.

According to a first aspect of the present invention, there is provided a power supply apparatus for an air conditioner, comprising: a sensing unit connected to a ground connection unit on an AC power source side to sense a current; A power converter connected to the AC power source and including an inverter for driving the motor; And an inverter controller connected to the sensing unit and determining whether the inverter is driven according to a voltage sensed by the sensing unit.

Here, the inverter control unit includes: a comparator that compares an input voltage sensed by the sensing unit with a reference voltage; A gate driver for driving the switching elements included in the inverter; And a controller for transmitting a drive cutoff signal to the gate driver according to the output voltage of the comparator.

At this time, the controller may transmit the drive cutoff signal to the gate driver when no current flows in the sensing unit.

In addition, the control unit may transmit the drive cutoff signal to the gate driver when the sensing unit senses 0 V or an offset voltage.

Here, the controller may transmit the drive cutoff signal to the gate driver when a surge voltage is sensed from the sensor.

At this time, the surge voltage may be set to 5 kV or more.

Here, when the drive cutoff signal is inputted to the gate driver, the driving of the switching element may be stopped and a signal for error display may be output.

Here, the sensing unit may include a current transformer (CT) or a shunt resistor.

Here, the inverter control unit may be connected to the sensing unit through a noise filter.

According to a second aspect of the present invention, there is provided a power supply apparatus for an air conditioner, comprising: a sensing unit connected to a ground connection unit on an AC power source side to sense a current; A power converter connected to the AC power source and including an inverter for driving the motor; And an inverter control unit connected to the sensing unit to stop the driving of the inverter when the sensing unit does not have a ground line connected to the ground connection unit or when a leakage current is sensed.

Here, the inverter control unit includes: a comparator that compares an input voltage sensed by the sensing unit with a reference voltage; A gate driver for driving the switching elements included in the inverter; And a controller for transmitting a drive cutoff signal to the gate driver according to the output voltage of the comparator.

Here, the inverter control unit may be connected to the sensing unit through a noise filter.

The present invention has the following effects.

According to the present invention, it is possible to prevent an electric shock accident by detecting the state where the ground connection part is not connected to the ground line, thereby preventing the air conditioner from being driven.

Also, by using such a current sensing circuit, the air conditioner can be protected by stopping the operation of the air conditioner even when a surge current due to a lightning stroke is applied or when a current of a magnitude larger than a specific leakage current is detected.

1 is a block diagram showing an example of a power conversion apparatus to which the present invention can be applied.
2 is a circuit diagram showing an example of a power conversion apparatus to which the present invention can be applied.
3 is an overall circuit diagram showing a power supply unit of an air conditioner according to an embodiment of the present invention.
4 is a schematic circuit diagram showing a power supply unit of an air conditioner according to an embodiment of the present invention.

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

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. Rather, the intention is not to limit the invention to the particular forms disclosed, but rather, the invention includes all modifications, equivalents and substitutions that are consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being present on another element "on," it may be directly on the other element or there may be an intermediate element in between .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and / or regions, such elements, components, regions, layers and / And should not be limited by these terms.

Fig. 1 is a block diagram showing an example of a power conversion apparatus to which the present invention can be applied, and Fig. 2 is a circuit diagram showing an example of a power conversion apparatus to which the present invention can be applied.

1 and 2, the power inverter 100 includes a rectifier 110 for rectifying an AC power source 10, a converter 120 for controlling the power factor of the DC voltage rectified by the rectifier 110, A converter control unit 130 for controlling the converter 120, an inverter 140 for outputting a three-phase AC current, an inverter control unit 150 for controlling the inverter 140 and a converter 120 and an inverter 140, And a DC-link capacitor C between the DC-link capacitors.

This inverter 140 outputs a three-phase alternating current, and this output current is supplied to the motor 200. Here, the motor 200 may be a compressor motor for driving the air conditioner. Hereinafter, the motor 200 is a compressor motor that drives the air conditioner, and the power inverter 100 is a motor driving device that drives such a compressor motor.

However, the motor 200 is not limited to a compressor motor and can be used in various applications using frequency-varying alternating voltages, for example, AC motors such as refrigerators, washing machines, electric trains, automobiles, and vacuum cleaners.

The motor driving apparatus 100 may further include a DC voltage detection unit B, an input voltage detection unit A, an input current detection unit D, and an output current detection unit E.

The motor drive apparatus 100 receives the AC power from the system, converts the power, and supplies the converted power to the motor 200.

The converter 120 converts the input AC power supply 10 into a DC power supply. The converter 120 may use a DC-DC converter operating as a power factor control (PFC) unit. In addition, such a DC-DC converter can use a boost converter. Optionally, the converter 120 may be a concept that includes the rectifier 110. Hereinafter, the converter 120 will be described by way of example using a step-up converter.

The rectifying unit 110 receives and rectifies the single-phase AC power supply 10 and outputs the rectified power to the converter 120 side. For this purpose, the rectifying part 110 can use a full-wave rectifying circuit using a bridge diode.

In this way, the converter 120 can perform the power factor improving operation in the process of stepping up and smoothing the voltage rectified by the rectifier 110.

The converter 120 includes an inductor L1 connected to the rectifying section 110, a switching device Q1 connected to the inductor L1, a capacitor C connected in parallel with the switching device Q1, And a diode D1 connected between the switching element Q1 and the DC-link capacitor C. [

The boost converter 120 can obtain an output voltage higher than the input voltage. When the switching device Q1 is turned on, the diode D1 is cut off and energy is stored in the inductor L1, and the DC-link capacitor C ) Discharges and generates an output voltage at the output terminal.

Further, when the switching element Q1 is interrupted, the energy stored in the inductor L1 at the time of the switching element Q1 is added and is transferred to the output terminal.

Here, the switching device Q1 may perform a switching operation by a separate pulse width modulation (PWM) signal. That is, the PWM signal transmitted from the converter control unit 130 is connected to the base (or gate) terminal of the switching element Q1, and the switching operation can be performed by the PWM signal.

The converter control unit 130 may include a gate driver for transmitting a PWM signal to a gate terminal of the switching element Q1 and a controller for transmitting a driving signal to the gate driver.

The switching element Q1 may use a power transistor, for example, an insulated gate bipolar mode transistor (IGBT).

The IGBT is a switching device having a structure of a metal oxide semi-conductor field effect transistor (MOSFET) and a bipolar transistor. The IGBT has a small driving power and is capable of high-speed switching, high-voltage conversion, and high current density.

In this manner, the converter control unit 130 can control the turn-on timing of the switching element Q1 in the converter 120. [ Thus, the converter control signal Sc for the turn-on timing of the switching element Q1 can be output.

The converter controller 130 may receive the input voltage Vs and the input current Is from the input voltage detector A and the input current detector D, respectively.

Optionally, such converter 120 and converter control 130 may be omitted. That is, the output voltage through the rectifying unit 110 can be charged to the DC-link capacitor C without passing through the converter 120, or the inverter 140 can be driven.

The input voltage detecting section A can detect the input voltage Vs from the input AC power supply 10. [ For example, at the front end of the rectifying part 110. [

The input voltage detecting section A may include a resistance element, an OP AMP, or the like for voltage detection. The detected input voltage Vs can be applied to the converter control unit 130 to generate a converter control signal Sc as a discrete signal in the form of a pulse.

Next, the input current detection unit D can detect the input current Is from the input AC power supply 10. [ Specifically, it may be located at the front end of the rectifying section 110. [

The input current detection unit D may include a current sensor, a current transformer (CT), a shunt resistor, or the like, for current detection. The detected input voltage Is may be applied to the converter control unit 130 to generate the converter control signal Sc as a discrete signal in the form of a pulse.

The DC voltage detecting section B detects the pulsating voltage Vdc of the DC-link capacitor C. For such power detection, a resistance element, OP AMP, or the like can be used. The voltage Vdc of the detected DC-link capacitor C may be applied to the inverter control unit 150 as a discrete signal in the form of a pulse, and the DC voltage Vdc of the DC-link capacitor C The inverter control signal Si can be generated.

On the other hand, unlike the drawing, the detected DC voltage is applied to the converter control unit 130 and may be used for generating the converter control signal Sc.

The inverter 140 includes a plurality of inverter switching elements Qa, Qb, Qc, Qa ', Qb' and Qc ', and supplies the smoothed DC power source Vdc to a predetermined frequency Phase AC power supply of the three-phase motor 200, and outputs the three-phase AC power to the three-phase motor 200.

Specifically, the inverter 140 is a pair of the upper switching elements Qa, Qb, and Qc and the lower switching elements Qa ', Qb', and Qc 'that are serially connected to each other, and a total of three pairs of upper and lower switching The devices can be connected in parallel with each other.

As with the converter 120, the switching elements Qa, Qb, Qc, Qa ', Qb', Qc 'of the inverter can use power transistors, for example, an insulated gate bipolar mode transistor ; IGBT) can be used.

The inverter control unit 150 can output the inverter control signal Si to the inverter 140 in order to control the switching operation of the inverter 140. [ The inverter control signal Si is a switching control signal of the pulse width modulation method PWM and is based on the output current io flowing through the motor 200 and the DC- link voltage Vdc across the DC- Can be generated and output. The output current io at this time can be detected from the output current detecting portion E and the DC-link voltage Vdc can be detected from the DC-link voltage detecting portion B.

The inverter control unit 150 includes a gate driver 151 for transmitting a PWM signal to the gate terminals of the switching elements Qa, Qb, Qc, Qa ', Qb' and Qc 'included in the inverter 140 And a control unit 152 (see FIG. 4) for transmitting a driving signal to the gate driving unit 151 as shown in FIG.

The output current detection section E can detect the output current io flowing between the inverter 140 and the motor 200. [ That is, the current flowing in the motor 200 is detected. The output current detection unit E can detect all of the output currents ia, ib, ic of each phase or can detect the output currents of two phases using the three-phase balance.

The output current detection unit E may be located between the inverter 140 and the motor 200. A current transformer CT or a shunt resistor may be used for detecting the current.

3 is an overall circuit diagram showing a power supply unit of an air conditioner according to an embodiment of the present invention.

3, the power supply unit of the air conditioner according to an embodiment of the present invention includes a sensing unit 160 connected to the ground connection unit G on the AC power source 10 side for sensing current, an AC power source The power converter 100 includes an inverter 140 for driving the motor 200. The power converter 100 is connected to the sensing unit 160 and is connected to the inverter 140 according to the voltage sensed by the sensing unit 160. [ And an inverter control unit 150 for determining whether to drive the motor.

Here, the AC power source 10 may be a three-phase power source including R-phase, S-phase, T-phase, and N-phase. Or a single-phase power source from which two phases are selected.

As described above, the sensing unit 160 is electrically connected to the ground connection G of the AC power source 10. The sensing unit 160 may be connected to the inverter control unit 150 through the noise filter 20.

The noise filter 20 can constitute a circuit including the inductor L _N and the capacitor C _N to remove the high frequency noise and the low frequency noise that can be applied from the AC power source 10. [

Here, the description of the power inverter 100 with reference to Figs. 1 and 2 can be applied equally.

At this time, the converter 120 of FIGS. 1 and 2 may be omitted. That is, a power source that is full-wave rectified through the rectifying unit 110 can be applied to the DC-link capacitor C, and the inverter 140 includes a plurality of switching elements Qa, Qb, Qc, and Qa ', Qb', Qc ') to drive the motor 200.

As described above, the inverter controller 150 includes a gate driver (not shown) for transmitting a PWM signal to the gate of the switching elements Qa, Qb, Qc, Qa ', Qb' and Qc 'included in the inverter 140, a gate driver 151 (see FIG. 4), and a controller 152 (see FIG. 4) for transmitting a driving signal to the gate driver 151. The configuration of the inverter control unit 150 will be described later in detail.

In addition, the matters related to the power conversion apparatus 100 may be applied equally to those described with reference to FIG. 1 and FIG.

Here, the sensing unit 160 may sense a leakage current such as a surge current when the ground line is not connected to the ground connection part G.

The right side of the AC power source 10 shows the internal connection configuration of the air conditioner, and the configuration is made at the time of manufacture in the factory. However, the left side of the AC power source 10 indicates a portion connected at the site when the air conditioner is installed.

At this time, in the inverter control unit 150, when the ground line is not connected to the ground connection unit G in the field or when the ground line (or the ground unit) is not connected to the ground connection unit G by mistake or when the surge current it is possible to stop the drive of the inverter 140 and display an error message when detecting a leakage current such as a surge current.

Most appliances, including air conditioners, are designed to connect the ground connection (G) to the ground wire during installation to reduce the risk of electric shock to the user due to leakage current. Especially in the case of air conditioners, it is possible to connect the ground to the surface of the product (where human hands can reach) when the appliance is installed.

However, since the presence or absence of the ground connection does not affect the operation of the air conditioner, it may happen that the ground wire is not connected to the ground connection portion (G) at the time of installation of the apparatus. In this case, if the human body touches the air conditioner during abnormal operation of the equipment, it may lead to electric shock accident due to leakage current.

In order to prevent such an accident, in the present invention, the current sensing circuit is configured through the sensing unit 160 and the inverter control unit 150 using the sensing unit 160 to sense the microcurrent in the ground connection unit G, It is possible to prevent the electric shock accident by preventing the air conditioner from being activated by sensing the state that it is not connected to the ground wire.

Also, by using such a current sensing circuit, the air conditioner can be protected by stopping the operation of the air conditioner even when a surge current due to a lightning stroke is applied or when a current of a magnitude larger than a specific leakage current is detected.

More specifically, the sensing unit 160 connected to the ground connection unit G always senses a current.

At this time, when the ground wire is not connected to the ground connection part G, that is, when the current sensed at the part where the leakage current flows to the ground during the operation of the device is "0A", the ground wire is not connected to the ground connection part It is possible to display an error message and stop the operation of the apparatus. Therefore, it is possible to prevent a situation in which an electric shock accident occurs due to a leakage current due to no connection of a ground wire to the ground connection part (G).

Also, when a surge occurs, a leakage current may be increased due to application of a high voltage. At this time, when the leakage current is detected by the sensing unit 160 and the leakage current becomes higher than a certain level, It is possible to prevent the product from burning due to lightning.

4 is a schematic circuit diagram showing a power supply unit of an air conditioner according to an embodiment of the present invention.

FIG. 4 mainly shows the detailed configuration of the inverter control unit 150. FIG.

4, the inverter control unit 150 includes a comparator 153 for comparing an input voltage sensed by the sensing unit 160 with a reference voltage, a gate driver 152 for driving a switching element included in the inverter, And a control unit 151 for transmitting a driving cutoff signal to the gate driving unit 152 according to an output voltage of the driving unit 153.

Here, the comparator 153 is configured to output a high signal when, for example, the voltage V _{in, which} is received by the output of the CT or shunt resistor included in the sensing unit 160, is greater than the reference voltage V _ref .

The comparator 153 may include an operational amplifier 154 and a setting resistor.

The control unit 151 controls the inverter and the motor through the gate driving unit 152. When the voltage V _in is 0 V (that is, when no current flows through the sensing unit 160) or when a predetermined offset voltage is detected It is possible to display an error message instead of outputting the PWM signal for driving the inverter.

For this operation, the controller 151 may control the gate driver 152 not to operate by sending a high signal to the terminal C _in which the gate driver 152 is cut off.

In this way, when the high (high) signal as the C-stage _in the gate driver 152 is input to stop the drive of the inverter can output a Fault signal is the error message signal.

On the other hand, the control unit 151, even when a surge voltage is sensed from the sensing unit 160 may transfer the signal to the drive block _in the C terminal of the gate driver 152. The

Hereinafter, the operation of the present invention will be described in detail with reference to Figs. 3 and 4. Fig.

As described above, according to the present invention, it is possible to confirm whether or not the ground line is connected to the ground connection part G, and to protect the device from lightning surge.

First, the process of checking whether there is a ground connection is explained.

If no ground is connected to the ground connection part G, a current will not flow through the CT or shunt resistor constituting the sensing part 160 and the output voltage V _in of the sensing part 160 is 0 V Or an offset is present, which may be 2.5 V).

This is applied to the sensing unit 160, the output voltage C _in stages of the gate driver 152 to sense the control unit 151 of the error message is displayed (or an error indication), and to prevent the operation of the air conditioner carried have.

On the other hand, the process of protecting the product from lightning (surge) is explained.

When the output voltage V _in of the sensing unit 160 reaches a specific reference level V _ref through the comparator 153, the output of the comparator 153 becomes high. This high signal may be applied to the C _in terminal of the gate driver 152 to indicate an error message (or an error indication) and to prevent the operation of the air conditioner. Therefore, burning of the air conditioner can be prevented.

In particular, since the magnitude of the leakage current may vary depending on the surge voltage, it is possible to configure the circuit so as to stop the device when the surge level is higher than the desired surge level.

Surge test specification should be able to drive without error to 1 kV or 2 kV and should restart after 4 kV error signal generation. However, equipment over 6 kV is allowed to be burned out and allowed only if there is no safety problem such as fire.

Even if a surge voltage higher than 6 kV is applied to the power supply device of the present invention as described above, it is possible to stop the product driving and prevent the device from being damaged.

In addition, it is possible to protect the device from abnormal operation and burn-out by stopping the product at a desired level (for example, 5 kV) by changing the reference level (Level; V _ref ) through resistance adjustment.

As a concrete example, it is assumed that the resistance of the comparator 153 is set so that the drive cut-off function operates at a surge voltage of 5 kV or more.

At this time, it is assumed that a leakage current of 50 mA is generated. This is assumed to be 50 mA at 5 kV considering less than 10 mA at 1.8 kV, the internal leakage current reference.

Thus, when the leakage current is 50 mA, the output voltage of the sensing unit 160 becomes 2.5 V.

At this time, 2.5 V, which is the output voltage of the sensing unit 160, is input to the comparator 153 when a surge voltage of 5 kV or more is applied, and a high signal is output.

The voltage thus outputted is applied to the terminal C _in , which is the terminal for cutting off the gate driving unit 152, so that the operation of the inverter is stopped and the operation of the entire apparatus is stopped.

If the leakage current is 0 mA, 0 V (or offset voltage 2.5 V) is output from the sensing unit 160, and it is determined that the ground wire is not connected, and the operation of the device is stopped.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

100: power converter 110: rectifying part
120: converter 130: converter control unit
140: inverter 150: inverter controller
151: Control unit 152: Gate driver
153: comparator 154: op amp
200: motor

Claims (12)

In a power supply unit of an air conditioner,
A sensing unit connected to the ground connection unit on the AC power source side to sense current;
A power converter connected to the AC power source and including an inverter for driving the motor; And
And an inverter controller connected to the sensing unit and determining whether the inverter is driven according to a voltage sensed by the sensing unit. 2. The inverter control apparatus according to claim 1,
A comparator for comparing an input voltage sensed by the sensing unit with a reference voltage;
A gate driver for driving the switching elements included in the inverter; And
And a controller for transmitting a drive cutoff signal to the gate driver according to an output voltage of the comparator. 3. The apparatus of claim 2,
And transmits the driving cut-off signal to the gate driving unit when no current flows in the sensing unit. The power unit of claim 3, wherein the controller transmits the driving cut-off signal to the gate driving unit when the sensing unit senses 0 V or an offset voltage. 3. The apparatus of claim 2,
And transmits the driving cut-off signal to the gate driving unit when a surge voltage is sensed from the sensing unit. 6. The power supply unit of an air conditioner according to claim 5, wherein the surge voltage is set to 5 kV or more. The power supply unit of an air conditioner according to claim 2, wherein when the drive cut-off signal is inputted to the gate driving unit, the driving of the switching device is stopped and a signal for error display is outputted. The power supply unit according to claim 1, wherein the sensing unit includes a current transformer (CT) or a shunt resistor. The power unit of claim 1, wherein the inverter control unit is connected to the sensing unit through a noise filter. In a power supply unit of an air conditioner,
A sensing unit connected to the ground connection unit on the AC power source side to sense current;
A power converter connected to the AC power source and including an inverter for driving the motor; And
And an inverter control unit connected to the sensing unit to stop driving the inverter when the ground line is not connected to the ground connection unit or when a leakage current is sensed by the sensing unit. Power supply. 11. The inverter control apparatus according to claim 10,
A comparator for comparing an input voltage sensed by the sensing unit with a reference voltage;
A gate driver for driving the switching elements included in the inverter; And
And a controller for transmitting a drive cutoff signal to the gate driver according to an output voltage of the comparator. 11. The power unit of claim 10, wherein the inverter control unit is connected to the sensing unit through a noise filter.

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