KR101873764B1 - Power transforming apparatus and air conditioner including the same - Google Patents

Abstract

The present invention relates to a power conversion apparatus, and more particularly, to a power conversion apparatus capable of protecting a DC stage capacitor and an air conditioner including the same. The present invention is characterized by comprising: a rectifying section for rectifying an AC input from an AC power source; A DC stage capacitor in which the DC output voltage of the rectifying unit is stored; And an inverter for converting the DC voltage into an AC power using a DC voltage stored in the DC capacitor; And a capacitor protection unit selectively connected to the DC stage capacitor to protect the DC stage capacitor.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power conversion apparatus and an air conditioner including the same,

The present invention relates to a power conversion apparatus, and more particularly, to a power conversion apparatus capable of protecting a DC stage capacitor and an air conditioner including the same.

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.

It is generally known that such a power conversion apparatus mainly constitutes a rectification section, a power factor control section, and an inverter type power conversion section.

First, the commercial voltage of the AC output from the commercial power source is rectified by the rectifying part. The voltage rectified in this rectifying part is supplied to a power converting part such as an inverter. At this time, the power converting unit generates AC power for driving the motor by using the voltage output from the rectifying unit.

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

A DC stage capacitor for charging a direct current (DC) voltage is provided between the rectification part or the converter and the inverter.

An abnormal condition such as a circuit test, a power overvoltage, a surge voltage application, or a regenerative current due to compressor deaeration may occur during operation of the power conversion apparatus, and the voltage applied to the DC stage capacitor may rise due to such an abnormal condition .

In this way, when an overvoltage is applied to the DC stage capacitor, the electrolytic solution inside the DC stage capacitor may boil, and the upper end of the DC stage capacitor may swell up and burn out.

Therefore, there is a need for a way to effectively protect such a DC stage capacitor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power conversion device capable of safely protecting a DC stage capacitor included in a power conversion device and an air conditioner including the same.

Also, it is an object of the present invention to provide a power conversion apparatus and an air conditioner including the power conversion apparatus that can safely protect a DC stage capacitor by reacting in real time from an overvoltage by a hardware configuration.

According to a first aspect of the present invention, there is provided a plasma processing apparatus comprising: a rectifying unit for rectifying an AC input from an AC power supply; A DC stage capacitor in which the DC output voltage of the rectifying unit is stored; And an inverter for converting the DC voltage into an AC power using a DC voltage stored in the DC capacitor; And a capacitor protection unit selectively connected to the DC stage capacitor to protect the DC stage capacitor.

Here, the capacitor protector may include an auxiliary capacitor selectively connected in series with the DC stage capacitor.

In this case, the capacitor protector may include: a voltage sensing unit for sensing a voltage across the capacitor; A comparator for comparing a voltage sensed by the voltage sensing unit with a set voltage; And a connection controller for connecting the DC capacitor and the auxiliary capacitor in series according to an output signal of the comparator.

The connection control unit may include: a first switching device having an output of the comparator connected to a base end and a collector end connected to the DC stage capacitor; And the auxiliary capacitor connected between the DC stage capacitor and the collector stage of the first switching device.

At this time, the set voltage may be 450V to 500V.

Here, a power factor control unit may be further provided between the rectifying unit and the DC stage capacitor to perform a power factor improving operation on the power outputted from the rectifying unit.

In this case, the power factor control unit may include an inductor connected to the rectifying unit; A second switching element connected to the inductor; The DC stage capacitor connected in parallel with the second switching device; And a diode connected between the second switching device and the DC stage capacitor.

As a second aspect of the present invention, the present invention can provide an air conditioner including the power conversion device described above.

The present invention has the following effects.

According to the present invention, even if the voltage of the DC link rises due to surge voltage generation and other abnormal conditions, the DC stage capacitor can be protected from overvoltage.

In the case of using a relay or using a software to cut off the voltage by using the converter control unit, the sensing time may be delayed and the DC-side capacitor may not be safely protected from overvoltage. According to the present invention, It can operate in response to the overvoltage, so that the capacitor can be safely protected from overvoltage.

1 is a block diagram showing an example of a power conversion apparatus.
2 is a circuit diagram showing an example of a power conversion apparatus.
3 is a circuit diagram showing a power conversion apparatus according to the first embodiment of the present invention.
4 is a perspective view showing a state in which the DC stage capacitor is damaged.
5 is a circuit diagram showing a power conversion apparatus according to a second 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, and Fig. 2 is a circuit diagram showing an example of a power conversion apparatus.

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-side capacitor C between the first and second 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 capacitor C. [

The boost converter 120 is a converter that can obtain an output voltage higher than the input voltage. When the switching device Q1 is turned on, energy is stored in the inductor L1 while the diode D1 is shut off, And the output voltage is generated at the output terminal while the charge is discharged.

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 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 is a device capable of small driving power, 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 control unit 130 may receive the input voltage Vs and the input current Is from the input voltage detection unit A and the input current detection unit B, respectively.

Optionally, such converter 120 and converter control 130 may be omitted. That is, the output voltage passing through the rectifying unit 110 can be charged to the DC stage capacitor C 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 stage capacitor C. For such power detection, a resistance element, OP AMP, or the like can be used. The detected voltage Vdc of the DC stage capacitor C may be applied to the inverter controller 150 as a discrete signal in the form of a pulse and may be applied to the DC voltage Vdc of the DC stage capacitor C The inverter control signal Si can be generated based on the inverter control signal Si.

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 generated based on the output current io flowing to the motor 200 and the DC short voltage Vdc across the DC short capacitor C as a switching control signal of the pulse width modulation method And output. The output current io at this time can be detected from the output current detection unit E and the DC short voltage Vdc can be detected from the DC voltage detection unit B. [

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. For current detection, a current transformer (CT), a shunt resistor, or the like may be used.

3 is a circuit diagram showing a power conversion apparatus according to the first embodiment of the present invention.

Referring to FIG. 3, there is a difference in that a power relay 111 for blocking an overvoltage is added to the AC power source 10, similar to the power conversion apparatus shown in FIG.

The DC stage capacitor C is detected by the converter controller 130 or the inverter controller 150. When the voltage of the DC stage is detected as 450 V or more, the power relay 111 is turned off to cut off the overvoltage.

However, since the power relay 111 is located at the front end of the rectifying unit 110, the voltage of the DC short capacitor C can be raised to about 600 V even if the power relay 111 is turned off to cut off the overvoltage.

The increased overvoltage may damage the DC capacitor C.

4 is a perspective view showing a state in which the DC stage capacitor is damaged.

Referring to FIG. 4, the DC capacitor C is burned out under abnormal conditions.

An abnormal condition such as a circuit test, a power supply overvoltage, a surge voltage application, or a regenerative current due to compressor deaeration may occur during the operation of the power conversion apparatus, and the voltage applied to the DC stage capacitor C rises can do.

In this way, when an overvoltage is applied to the DC stage capacitor C, the electrolyte inside the DC stage capacitor C may be boiled, and the upper end A of the DC stage capacitor C Burning can occur while swelling up.

Actually, the voltage limit of the DC-use capacitor C mainly used is about 450V.

5 is a circuit diagram showing a power conversion apparatus according to a second embodiment of the present invention. Referring to FIG. 5, there is shown a power conversion device capable of preventing burn-out of the DC short capacitor C1 as described above.

FIG. 5 mainly shows the configuration after the DC stage capacitor C1 in the power conversion apparatus.

That is, the power conversion apparatus according to an embodiment of the present invention includes a DC stage capacitor C1, an inverter 140 that converts the DC voltage stored in the DC stage capacitor C1 into an AC power source, And a capacitor protection unit 160 selectively connected to the DC capacitor C1 to protect the DC capacitor C1.

The capacitor protection unit 160 may include an auxiliary capacitor C2 selectively connected in series with the DC-side capacitor C1.

The capacitor protection unit 160 includes a voltage sensing unit 161 for sensing a voltage across the DC capacitor C1 and a comparator 162 for comparing the voltage sensed by the voltage sensing unit 161 with a set voltage. And a connection controller 164 for connecting the DC stage capacitor C1 and the auxiliary capacitor C2 in series according to the output signal of the comparator 162. [

Here, the voltage sensing unit 161 may use a distribution resistor including a first resistor R1 and a second resistor R2.

The comparator 162 may include an OP Amp 163 and a third resistor R3 and a fourth resistor R4 for setting a voltage for overvoltage determination. The output voltage of the voltage sensing unit 161 is applied to the comparator 162.

In addition, the connection control section 164 may include a first switching device Q2 whose output is connected to the base end of the comparator 162 and whose collector terminal is connected to the DC-side capacitor C1.

The above-mentioned auxiliary capacitor C2 may be connected between the DC stage capacitor C1 and the collector stage of the first switching device Q2.

The other end of the auxiliary capacitor C2 may be connected to the ground, and the emitter end of the first switching device Q2 may also be connected to the ground.

At this time, the set voltage at which the connection control unit 164 operates, that is, the voltage setting applied across the DC-side capacitor C1 may be 450V to 500V. In Fig. 5, as an example, the setting in the case where the voltage setting is 500 V is shown. That is, the values of the first to fourth resistors R1 to R4 shown in FIG. 5 are set according to the voltage setting of 500V.

Here, as shown in Figs. 2 and 3, a rectifying unit 110 (see Figs. 2 and 3) for supplying DC power to the DC stage capacitor C1 may be constructed.

In addition, the power factor control unit 120, which is located in the rectification unit 110 and the DC stage capacitor C1 and performs the power factor control function, may be further comprised, but the illustration is omitted in FIG.

As described above, the power factor control unit 120 may configure a boost converter.

2 and 3, the power factor control unit 120 includes an inductor L connected to the rectifying unit 110, a capacitor C1 connected to the inductor L1 and connected in parallel to the DC capacitor C1 or C1, And a diode D1 connected between the second switching element Q1 and the DC-side capacitor C or C1, as shown in FIG.

Meanwhile, an inverter 140 for driving the motor 200 is formed in the DC stage capacitor C1.

As described above, the inverter 140 may be provided with switching elements Qa, Qb, Qc, Qa ', Qb', and Qc 'for driving the three-phase motor 200. In this manner, the inverter 140 generates a three-phase power signal for driving the three-phase induction motor 200.

Hereinafter, the operation of the power conversion apparatus according to the embodiment of the present invention will be described in detail with reference to FIG.

As described above, the voltage setting for protecting the DC short capacitor C1, that is, the condition for the connection control part 164 of the capacitor protection part 160 to operate, may be 450V to 500V.

Hereinafter, a case where the voltage for protecting the DC-side capacitor C1 is 500V will be described as an example.

The voltage applied across the DC short capacitor C1 is detected by the distribution resistors R1 and R2 constituting the voltage sensing unit 161 of the capacitor protection unit 160. [

First, when the voltage applied to both ends of the DC short capacitor C1 is equal to or lower than the set voltage, that is, 500V or less, the applied voltage is sensed by the distribution resistors R1 and R2 and input to the comparator 162.

At this time, if the voltage sensed by the voltage sensing unit 161, that is, the voltage sensed by the resistance distribution, is below a predetermined voltage, the comparator 162 outputs a high signal.

That is, the comparator 162 outputs a high signal when the voltage applied across the DC capacitor C1 is 500 V or less.

At this time, the high signal outputted from the comparator 162 is inputted to the base end (gate end) of the first switching device Q2 provided in the connection control unit 164, so that the first switching device Q2 is turned on Only the ON-state DC-step capacitor C1 is operated.

On the other hand, when the voltage applied across the DC capacitor C1 is a set voltage, that is, 500 V or more, the applied voltage is sensed by the distribution resistors R1 and R2 and input to the comparator 162.

At this time, if the voltage sensed by the voltage sensing unit 161, that is, the voltage sensed by the resistance distribution, is equal to or higher than a predetermined voltage, the comparator 162 outputs a low signal.

That is, the comparator 162 outputs a low signal when the voltage applied across the DC capacitor C1 is 500 V or more.

At this time, a low signal output from the comparator 162 is input to the base end (gate end) of the first switching device Q2 provided in the connection control unit 164 to turn off the first switching device Q2 (off).

Then, the DC short capacitor C1 and the auxiliary capacitor C2 are connected in series to operate at a large capacity, thereby protecting the DC short capacitor C1 from the high voltage.

Therefore, even if the voltage of the DC link rises due to surge voltage generation and other abnormal conditions, the DC capacitor C1 can be protected from the overvoltage.

In fact, in the case of a capacitor having a product limit of 460 V, it was confirmed that a capacitor can be safely protected even when a voltage of 620 V is applied for one minute.

As described above, when the relay is used or the converter control unit cuts off the voltage by using the software, the sensing time may be delayed and the DC capacitor C1 may not be safely protected from the overvoltage. The hardware such as the comparator can operate in response to the overvoltage in real time, so that the capacitor C1 can be safely protected from the overvoltage.

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
160: capacitor protecting unit 161: voltage detecting unit
162: comparator 164: connection control unit
200: motor

Claims (8)

A rectifying unit for rectifying AC input from the AC power source;
A DC stage capacitor in which the DC output voltage of the rectifying unit is stored;
An inverter for converting the DC voltage stored in the DC capacitor to an AC voltage; And
And a capacitor protection unit for protecting the DC-side capacitor by including an auxiliary capacitor selectively connected in series with the DC-side capacitor. delete The plasma display apparatus of claim 1,
A voltage sensing unit for sensing a voltage across the capacitor;
A comparator for comparing a voltage sensed by the voltage sensing unit with a set voltage; And
And a connection controller for connecting the DC capacitor and the auxiliary capacitor in series according to an output signal of the comparator. 4. The apparatus of claim 3,
A first switching device having an output of the comparator connected to a base end and a collector terminal connected to the DC stage capacitor; And
And the auxiliary capacitor connected between the DC stage capacitor and the collector stage of the first switching device. 4. The power conversion apparatus according to claim 3, wherein the set voltage is 450V to 500V. The power conversion apparatus according to claim 1, further comprising a power factor control unit between the rectification unit and the DC stage capacitor for performing a power factor improving operation on the power source output from the rectifying unit. The power control apparatus according to claim 6,
An inductor connected to the rectifying part;
A second switching element connected to the inductor;
The DC stage capacitor connected in parallel with the second switching device; And
And a diode connected between the second switching device and the DC stage capacitor. An air conditioner comprising the power conversion device according to any one of claims 1 to 7.

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