KR20190019289A - Power transforming apparatus, Method for controlling the same and Air conditioner including the power transforming apparatus - Google Patents

Abstract

The objective of the present invention is to provide a power conversion apparatus which can continuously use home appliance by sensing that a main fuse is damaged by overcurrent while using the power conversion apparatus to enable the power conversion apparatus to be conductive through an emergency fuse. The power conversion apparatus comprises: a converter converting an alternating current power source into a direct current power source, raising/reducing DC voltage or improving a power factor; an overcurrent protection unit connected between the alternating current power source and the converter and including a plurality of fuses; and a control unit controlling current to flow through another fuse when the overcurrent protection unit senses that the current passing through one fuse is less than or equal to a reference value.

Description

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

The present invention relates to an air conditioner including a power conversion apparatus, a control method thereof, and a power conversion apparatus.

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

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.

At this time, the voltage output from the rectifying unit or the voltage output from the converter is charged in the DC-link capacitor, and the motor drive signal can be generated in the inverter using the charged voltage.

A fuse is connected to the AC power source of the power conversion apparatus to prevent the circuit element from being burned out by the overcurrent.

When an overcurrent occurs in an electric circuit, the fuse is blown out to cut off the current, and the user can reuse the electric circuit by replacing the fuse.

In some cases, however, the fuse attached to the electric device may not be used due to defects during manufacture, burning during transportation or use, or conduction current not reaching the reference value.

The user must then replace the fuse with a new one so that the electric device can be used properly.

As described above, when the user uses the electric device for a predetermined period of time or more, the fuse is not burned. If the fuse is bad at the beginning of use, the electric device is stopped and the user can use the electric device by replacing with a new fuse. .

On the other hand, Korean Patent Registration No. 10-1146694 discloses a secondary battery protection circuit capable of self-monitoring of fuse failure, a battery pack using the same, and a battery assembly classification method including a defective fuse.

However, this is because the defective fuse is monitored during the manufacturing process, so there is a problem that the defective fuse is detected during the actual use and the electric device can not be operated in an emergency.

An object of the present invention is to provide a power conversion device capable of continuously using a household appliance by detecting a main fuse burned by an overcurrent while the power conversion device is being used and allowing the main fuse to be energized through an emergency fuse.

According to an aspect of the present invention, there is provided a power conversion apparatus comprising: a converter for converting an AC power source to a DC power source, boosting / reducing a DC voltage or improving a power factor; An overcurrent protection unit connected between the AC power source and the converter and including a plurality of fuses; And a control unit for controlling the current to flow through another fuse when the overcurrent protection unit senses that the current passing through the one fuse is below the reference value.

Wherein the overcurrent protection unit comprises: a main fuse connected between the AC power source and the converter; An emergency fuse connected in parallel to the main fuse; A relay connected in series to said emergency fuse; And a current sensing unit provided between the main fuse and the converter.

The control unit preferably turns on the relay so as to be energized through the emergency fuse when the current sensing unit detects that the energization current is lower than the reference value.

An inverter connected to the converter for outputting three-phase AC power; And a DC-link capacitor connected in parallel between the converter and the inverter.

The control unit preferably controls operation of the converter and the inverter.

The air conditioner of the present invention includes the power conversion device as described above.

A control method of a power conversion apparatus according to the present invention is a control method of a power conversion apparatus including an overcurrent protection unit in which a main fuse and an emergency fuse are connected in parallel between an AC power source and a converter, A first step of operating the first step; And a second step of sensing a current passing through the main fuse. And a third step of passing current through the emergency fuse when a current passing through the main fuse is less than a reference value.

In the second step, it is preferable that a current sensing unit provided between the main fuse and the converter senses a current flowing through the main fuse.

In the third step, if the energization current is lower than the reference value, turning on the relay connected in series to the emergency fuse and energizing the emergency fuse through the emergency fuse.

The control method of the power conversion apparatus may further include: a fourth step of sensing the energizing current of the emergency fuse by the current sensing unit; And a fifth step of turning off the relay and informing replacement of the fuse if the energization current of the emergency fuse is less than a reference value.

According to the present invention, when the main fuse is burned out by the overcurrent while the power converter is being used, the main fuse is sensed and energized through the emergency fuse so that the household appliance can be continuously used.

Therefore, even if the product can not be used due to a simple defect of the fuse or the like, the product can be used by detecting it and automatically energizing it through the emergency fuse.

1 is a circuit diagram showing a power conversion apparatus according to an embodiment of the present invention.
2 is a flowchart showing a control method of a power conversion apparatus according to an embodiment of the present invention.
Fig. 3 is a circuit diagram showing control to be conducted through the emergency fuse in Fig. 1. Fig.

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

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

Referring to FIG. 1, a power conversion apparatus includes a converter 40 for converting AC power to DC power, boosting / reducing DC voltage or improving the power factor, and a plurality of fuses connected between the AC power source and the converter An overcurrent protection unit 20, and a control unit 70 for controlling the overcurrent protection unit.

The power converter includes an inverter 60 connected to the converter 40 to output three-phase AC power, and a DC-link capacitor C connected in parallel between the converter 40 and the inverter 60 .

The converter 40 may include a rectifying section for rectifying the AC power source 10 and a power factor control section for boosting / reducing the DC voltage rectified by the rectifying section or for controlling the power factor.

The rectification section converts the input AC power source 10 into DC power, and outputs the rectified power to the power factor control section side. To this end, the rectifying part may be constituted by a full-wave rectifying circuit using a bridge diode.

The power factor control unit may use a DC-DC converter. In addition, such a DC-DC converter can use a boost converter. Hereinafter, the power factor control unit will be described taking the case of using a voltage-up converter as an example.

In this manner, the power factor control unit can perform the power factor improving operation in the process of stepping up and smoothing the voltage signal rectified by the rectifying unit.

The power factor control unit may include an inductor connected to the rectifying unit, a switching device connected to the inductor, and a diode connected between the switching device and the DC-link capacitor.

The step-up converter is a converter that can obtain an output voltage higher than the input voltage. When the switching element is turned on, energy is stored in the inductor while the diode is cut off. The charge stored in the DC- Thereby generating a voltage.

In addition, when the switching element is cut off, the energy stored in the inductor at the time of switching element conduction is added to the output terminal.

Here, the switching device can perform a switching operation by a separate PWM (Pulse Width Modulation) signal. That is, the PWM signal transmitted from the converter control unit is connected to the gate (or base) terminal of the switching element, and the switching operation can be performed by the PWM signal.

The converter control unit may include a gate driving unit for transmitting a PWM signal to a gate terminal of the switching device, and a control unit for transmitting a control signal to the gate driving unit.

Such a switching device can 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 way, the converter control section can control the turn-on timing of the switching element in the power factor control section. Thus, the converter control signal for the turn-on timing of the switching element can be outputted.

To this end, the converter control unit may receive the input voltage and the input current from the input voltage detecting unit and the input current detecting unit, respectively.

The input current detecting section is located at the previous stage of the rectifying section and can detect the input current from the alternating current power supply 10.

The input current detection unit may include a current sensor, a current transformer (CT), a shunt resistor, and the like, for current detection. The detected input current may be a discrete signal in the form of a pulse and may be applied to the converter control for generation of the converter control signal.

The input voltage detecting unit is located at the previous stage of the rectifying unit and can detect the input voltage from the AC power source 10. [

The input voltage detecting unit may include a resistive element, an OP AMP, or the like for voltage detection. The detected input voltage is a discrete signal in the form of a pulse and can be applied to the converter control section for generation of the converter control signal.

The inverter 60 can be driven by applying a driving signal by the inverter control unit.

This inverter 60 outputs a three-phase alternating current, and this output current is supplied to the motor 70. Here, the motor 70 may be a compressor motor for driving the air conditioner. Hereinafter, the motor 70 is a compressor motor for driving the air conditioner, and the power converter is a motor driving device for driving such a compressor motor.

However, the motor 70 is not limited to a compressor motor, and can be used in various applications using frequency-variable AC voltages, for example, AC motors such as refrigerators, washing machines, electric trains, automobiles, and vacuum cleaners.

On the other hand, the motor drive apparatus may further include a DC voltage detection section and an output current detection section. The motor drive apparatus receives AC power from the system, converts the power, and supplies the converted three-phase power to the motor (70).

The DC voltage detection unit detects the pulsating voltage of the DC-link capacitor C. For such power detection, a resistance element, OP AMP, or the like can be used. The detected voltage of the DC-link capacitor C can be applied to the inverter control unit as a discrete signal in the form of a pulse, and an inverter control signal is generated based on the DC voltage of the DC- .

The output current detection section can detect the output current flowing between the inverter (60) and the motor (70). That is, the current flowing in the motor 70 is detected. The output current detection unit can detect all the output currents of the respective phases, or can detect the output currents of the two phases using the three-phase balance.

The output current detection unit may be located between the inverter 60 and the motor 70. For current detection, a current transformer (CT), a shunt resistor, or the like may be used.

The inverter 60 includes a plurality of inverter switching elements. The inverter 60 converts the smoothed direct current power to a three-phase alternating current power of a predetermined frequency by the on / off operation of the switching elements of the power factor control section, Can be output.

Specifically, the inverter 60 is a pair of upper and lower switching elements serially connected to each other, and a total of three pairs of the upper and lower switching elements may be connected in parallel to each other.

As in the case of the power factor control unit, the switching element of the inverter 60 may use a power transistor, for example, an insulated gate bipolar mode transistor (IGBT).

The inverter control unit can output an inverter control signal to the inverter 60 to control the switching operation of the inverter 60. [ The inverter control signal can be generated and output based on the output current flowing to the motor 70 and the DC-link voltage across the DC-link capacitor C as a switching control signal of the pulse width modulation method (PWM). The output current at this time can be detected from the output current detection section, and the DC-link voltage can be detected from the DC-link voltage detection section.

The inverter control unit may include a gate driver for transmitting a PWM signal to a gate terminal of a switching element included in the inverter 60 and a control unit for transmitting a control signal to the gate driver.

The control unit for applying the control signal to the gate driving unit of the power factor control unit and the control unit for applying the control signal to the gate driving unit of the inverter 60 may be the same. That is, one controller 70 can control the gate driver for driving the switching elements included in the power factor control unit and the gate driver for driving the switching elements included in the inverter 60. The control unit 70 can also control the relay 23 provided in the overcurrent protection unit 20 as described later.

In general, a fuse is connected in series between a power source and a power conversion device in order to protect a circuit by an overcurrent. In the present invention, a plurality of fuses 21 and 22 and a relay And an overcurrent protection unit 20 including an overcurrent protection unit 23.

The plurality of fuses 21 and 22 may include a main fuse 21 connected between the AC power supply 10 and the converter 40 and an emergency fuse 22 connected in parallel to the main fuse 21. [ have.

The relay 23 is connected in series to the emergency fuse 22 and can be switched on when the emergency fuse 22 is to be energized.

That is, the emergency fuse 22 and the relay 23 are connected in parallel to the main fuse 21, and when the main fuse 21 is disconnected by the overcurrent, the relay 23 is turned on and the emergency fuse 22 is turned on, Lt; / RTI >

The control unit 70 can control the current to flow through the emergency fuse 22 when the overcurrent protection unit 20 detects that the current supplied to the main fuse 21 is lower than the reference value.

For this purpose, a current sensing unit 25 may be provided between the main fuse 21 and the converter 40. [ The current detection unit 25 may correspond to the input current detection unit.

The current value sensed by the current sensing unit 25 is received by the controller 70 and becomes a reference for turning on / off the relay 23 or a reference for controlling the switching element of the converter 40 .

The control unit 70 determines that the main fuse 21 is defective when the current sensing unit 25 detects that the energizing current is below the reference value and turns on the relay 23 so that the main fuse 21 is energized through the emergency fuse 22 .

Then, the AC power supply 10 is conducted through the emergency fuse 22 so that the power conversion apparatus can be operated, unless the overcurrent continues to flow through the power conversion apparatus.

If there is a problem with the AC power source 10, the power converter or the load, and the overcurrent flows, the emergency fuse 22 energized above will also be fused immediately. In such a case, after the problem is solved, the main fuse 21 and the emergency fuse 22 may be replaced and used.

FIG. 2 is a flowchart showing a control method of the power conversion apparatus according to an embodiment of the present invention, and FIG. 3 is a circuit diagram showing control to be conducted through an emergency fuse in FIG.

Hereinafter, a control method of the power conversion apparatus will be described.

First, the user connects the power source of the air conditioner and inputs the operation start command through the control unit 70 (S10).

Then, the control unit 70 starts operating the product (S20).

At this time, the AC power supply 10 is supplied to the power conversion apparatus through the main fuse 21, and the current sensing unit 25 senses a current conducted to the main fuse 21 and supplies the sensing signal to the controller 70 (S30). Current sensing by the current sensing unit 25 is continuously performed in real time until the product operation is stopped after the product operation is started.

The controller 70 determines whether the sensed current is below the reference value (S40). If the current conducted to the main fuse 21 is larger than the reference value, the product operation state is maintained.

If the sensed current becomes lower than the reference value, the controller 70 issues a product operation stop command to temporarily stop the product operation (S50). This operation stop command corresponds to a drive correction command of the motor 80 as a load.

The controller 70 turns on the relay 23 so that the AC power source 10 is made conductive through the emergency fuse 22 in step S60.

3, the main fuse 21 is fused and the relay 23 is turned on by the controller 70 sensing the current so that the current is conducted through the emergency fuse 22, A situation is shown that is supplied to the conversion apparatus.

Then, since the AC power supply 10 can be supplied to the power conversion apparatus, the controller 70 applies the product operation command again to operate the product (S70).

As described above, the controller 70 receives the current sensing signal from the current sensing unit 25 in real time.

Thus, the controller 70 continuously determines whether the sensed current of the current sensing unit 25 is below the reference value (S80).

If the sensed current falls below the reference value, it can be determined that the emergency fuse 22 is fused or defective. Therefore, the control unit 70 stops the operation of the product (S90).

Then, the control unit 70 instructs the user to replace the fuse through the display unit provided in the indoor unit (S100), and allows the user to use the product after replacing the main fuse 21 and the emergency fuse 22 .

According to the present invention, when the main fuse is burned out by the overcurrent during use of the power conversion apparatus, the main fuse is sensed and energized through the emergency fuse so that the household appliance can be continuously used.

Therefore, even if the product can not be used due to a simple defect of the fuse or the like, the product can be used by detecting it and automatically energizing it through the emergency fuse.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Changes will be possible.

10: AC power supply 20: Overcurrent protection unit
21: main fuse 22: emergency fuse
25: current sensing unit 40: converter
60: inverter 70:
80: Motor

Claims (10)

A converter for converting AC power into DC power and for boosting / reducing DC voltage or improving power factor;
An overcurrent protection unit connected between the AC power source and the converter and including a plurality of fuses; And
And a controller for controlling the current to be passed through another fuse when the overcurrent protection unit senses that the current passing through one fuse is below the reference value. The method according to claim 1,
The overcurrent protection unit includes:
A main fuse connected between the AC power source and the converter;
An emergency fuse connected in parallel to the main fuse;
A relay connected in series to said emergency fuse; And
And a current sensing unit provided between the main fuse and the converter. 3. The method of claim 2,
Wherein the control unit turns on the relay so as to be energized through the emergency fuse when the current sensing unit detects that the energizing current is lower than the reference value. The method according to claim 1,
An inverter connected to the converter for outputting three-phase AC power; And
And a DC-link capacitor connected in parallel between the converter and the inverter. 5. The method of claim 4,
And the control unit controls operation of the converter and the inverter. An air conditioner comprising the power conversion device according to any one of claims 1 to 5. A control method of a power conversion apparatus including an overcurrent protection unit in which a main fuse and an emergency fuse are connected in parallel between an AC power source and a converter,
A first step of energizing the power converter through the main fuse; And
A second step of sensing a current passing through the main fuse; And
And a third step of conducting current through the emergency fuse when a current passing through the main fuse is less than a reference value. 8. The method of claim 7,
Wherein in the second step, the current sensing unit of the main fuse and the converter detects the current of the main fuse. 9. The method of claim 8,
And if the energization current is lower than a reference value, turning on a relay connected in series to the emergency fuse and energizing the emergency fuse through an emergency fuse in the third step. 10. The method of claim 9,
A fourth step of sensing the energizing current of the emergency fuse by the current sensing unit; And
Further comprising a fifth step of turning off the relay and informing replacement of the fuse if the energizing current of the emergency fuse is less than a reference value.

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