KR20190010989A - Power transforming apparatus and air conditioner including the same - Google Patents

Abstract

The present invention provides a power conversion apparatus and an air conditioner including the same to have an inrush current prevention function for preventing component damage by overcurrent. The power conversion apparatus comprises: a first rectifying unit rectifying current inputted from an alternating current power source; a first DC-link capacitor stored with DC voltage rectified by the rectifying unit; an inrush current prevention unit including a power relay which is connected between the alternating current power source and the first rectifying unit and maintains a switching state without additional power supply, a charging resistor which is connected in series with the power relay, and a charging relay which is connected in parallel with the charging resistor; a current detecting unit connected between the inrush current prevention unit and the first rectifying unit and detecting whether the alternating current power source is supplied to the first rectifying unit; and a control unit controlling the charging relay for the current to flow through the charging resistance until the first DC-link capacitor is charged with a predetermined amount of voltage and turning the power relay off when detecting power cutoff by the current detecting unit.

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 an air conditioner including the same, and more particularly, to a power conversion apparatus having an inrush current prevention function 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.

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.

However, an inrush current may be generated at the beginning of the operation of the power converter, and the inrush current may be passed through a charging resistor of a large capacity so as not to be directly applied to the power converter.

At this time, a large capacity charging resistor and a large number of relays are used to prevent the inrush current, thereby increasing the space shortage and the control factor, thereby causing a problem of generating additional cost.

Korean Patent Laid-Open No. 10-2006-0018703 discloses an inverter inrush current prevention circuit and a method for preventing the inverter.

In the case of an inverter using a three-phase AC power source, an inrush current may be generated at the time of the initial charge because a high-voltage power source is applied and a capacitor having a high capacity is used. The inrush current prevention circuit of the disclosed inverter includes a first relay connected in series with a neutral line of a three-phase AC power source to open and close a connection of a neutral line, and a second relay connected in series to a minus terminal of the inverter rectifier, And a second relay for opening and closing the connection of the second relay.

However, in order to keep the second relay used as the power relay in the ON state, current must be continuously supplied to the relay coil, which causes power loss.

The present invention solves the problem of insufficient space and increase in control elements by using a large capacity charging resistor and a plurality of relays, prevents an inrush current from being applied at the beginning of driving of the air conditioner, A power conversion device having an inrush current prevention function capable of preventing part burnout due to an overcurrent by turning off a power relay by detecting a power supply interruption when the power supply is interrupted and an air conditioner including the same The purpose.

According to an aspect of the present invention, there is provided a power conversion apparatus comprising: a first rectifying unit for rectifying an AC input from an AC power source; A first DC-link capacitor charged with a DC voltage rectified by the rectifying unit; A power relay connected between the AC power source and the first rectifying part and maintaining a switching state without additional power supply, a charging resistor connected in parallel with the power relay, and a charging relay connected in series with the charging resistor, part; A current sensing unit connected between the inrush current preventing unit and the first rectifying unit to sense whether the AC power is supplied to the first rectifying unit; And controlling the charge relay so that a current flows through a charging resistor until a voltage of a predetermined capacity is charged in the first DC-link capacitor, and when the current sensing unit senses that the power supply is interrupted, (Off).

The power relay is preferably a latch relay.

The latch relay may include a set coil to which a set signal for turning on the power relay is applied, and a reset coil to which a reset signal for turning off the power relay is applied.

The inrush current prevention unit may further include a first transistor connected between the control unit and the set coil, and a second transistor connected between the control unit and the reset coil.

A second rectifying unit for rectifying an AC input from the AC power source; A second DC-link capacitor charged with a DC voltage rectified by the second rectification part; And an SMPS connected to the second DC-link capacitor, wherein the controller receives DC power from the SMPS.

The first DC-link capacitor and the second DC-link capacitor are preferably connected by a bypass diode.

When the charging voltage of the first DC-link capacitor reaches a target value within a predetermined time, the controller transmits a set signal to the latch relay to turn on the latch relay, (On), and then the charging relay is turned off.

The controller may transmit a reset signal to the latch relay to turn off the latch relay when the current sensing unit detects that the power supply is interrupted.

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

According to the power conversion apparatus of the present invention and the air conditioner including the same, the DC-link voltage can be stably charged without an inrush current at the start of operation of the air conditioner, so that the power conversion apparatus can operate.

Further, by using the latch relay with the power relay, the switching state can be maintained even when the relay coil is not energized after the relay is turned on / off, so that the power consumption can be reduced.

When the latch relay is turned on, it is detected when the power supply is suddenly stopped, such as a power failure, and a latch relay off signal is applied to prevent component burnout due to overcurrent.

1 is a block diagram showing a power conversion apparatus having an inrush current prevention function according to an embodiment of the present invention.
2 is a circuit diagram showing a power conversion apparatus having an inrush current prevention function according to an embodiment of the present invention.
3 is a circuit diagram showing details of an inrush current prevention unit of a power conversion apparatus having an inrush current prevention function according to an embodiment of the present invention.
4 is a flowchart showing the operation of a power conversion apparatus having an inrush current prevention function according to an embodiment of the present invention.
5 to 7 are circuit diagrams showing the operation of a power conversion apparatus having an inrush current prevention function according to an embodiment of the present invention.

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

FIG. 1 is a block diagram showing a power conversion apparatus having an inrush current prevention function according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a power conversion apparatus having an inrush current prevention function according to an embodiment of the present invention .

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 alternating current, an inverter control unit 150 for controlling the inverter 140, and a converter 120 and an inverter 140 (DC-link) capacitor C1 between the input terminal and the output terminal.

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 using a boost converter as an example.

The rectifying unit 110 receives and rectifies the AC power source 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.

As described above, the converter 120 can perform the power factor improving operation in the process of stepping up and smoothing the voltage signal rectified by the rectifying unit 110. [

The converter 120 includes an inductor L1 connected to the rectifying section 110, a switching element Q1 connected to the inductor L1, and a switching element Q1 connected between the switching element Q1 and the DC-link capacitor C1. And a diode D1.

The step-up converter 120 is a converter that can obtain an output voltage higher than the input voltage. When the switching element Q1 is turned on, the diode D1 is cut off and energy is stored in the inductor L1. ) 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 gate (or base) terminal of the switching element Q1, and the switching operation can be performed by the PWM signal.

The converter control unit 130 includes a gate driver 131 for transmitting a PWM signal to the gate terminal of the switching element Q1 and a control unit 152 for transmitting a control signal to the gate driver 131 .

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 C1 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 current Is can be applied to the converter control unit 130 for generation of 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 C1. For such power detection, a resistance element, OP AMP, or the like can be used. The detected voltage Vdc of the DC-link capacitor C1 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 C1 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 is turned on and off by the switching element Q1 of the converter 120 It is possible to convert the DC power supply Vdc into a three-phase AC power supply of a predetermined frequency, and output it 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.

The switching elements Qa, Qb, Qc, Qa ', Qb', and Qc 'of the inverter 140 may be power transistors, for example, an insulated gate bipolar transistor bipolar mode transistor (IGBT)).

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 to 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 controller 150 includes a gate driver 151 for transmitting a PWM signal to the gate of the switching elements Qa, Qb, Qc, Qa ', Qb' and Qc 'included in the inverter 140, And a control unit 152 for transmitting a control signal to the gate driving unit 151.

2, a control unit 152 for controlling the control signal to the gate driving unit 131 of the converter 120 and a control unit 152 for controlling the control signal to the gate driving unit 151 of the inverter 140 ) May be the same. That is, one control unit 152 can control the gate driving unit 131 driving the switching elements included in the converter 120 and the gate driving unit 151 driving the switching elements included in the inverter 140.

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.

2, a DC-link capacitor or the power inverter 100 is connected between the AC power supply Vs and the converter 120 or the rectifier 110 during the initial operation of the power inverter 100. [ An inrush current prevention unit 160 that protects the current from current can be provided.

The inrush current prevention part 160 is provided with a charging resistor R1 having a large capacity (see FIG. 3), so that the power conversion device can be protected from the inrush current flowing when the power is first applied to the power conversion device.

That is, the inrush current prevention unit 160 controls the current flow so that current flows through the charging resistor R1 until the DC-link voltage charged in the DC-link capacitor C1 reaches the target value, It is possible to prevent the inrush current from being directly applied to the power converter at the initial stage.

3 is a circuit diagram showing details of an inrush current prevention unit of a power conversion apparatus having an inrush current prevention function according to an embodiment of the present invention.

3, a rectifier 110 for rectifying an AC power source 10 among the power converters, an inverter 140 for outputting an AC current, and a DC-link DC / DC converter 130 for connecting between the rectifier 110 and the inverter 140. [ -link capacitor C1.

The inverter 140 can output the rectified power as a three-phase or single-phase alternating current.

Although the converter 120 shown in FIGS. 1 and 2 is not shown in FIG. 3, the converter 120 may be omitted from FIG. 3 or may not be provided at all.

An inrush current prevention unit 160 is connected between the AC power source 10 and the rectification unit 110. In the inrush current prevention unit 160, the control unit 152 controls the switching operation of the relay.

The inrush current prevention unit 160 includes a power relay 165 connected between the AC power source 10 and the rectifying unit 110, a charging resistor R1 connected in parallel to the power relay 165, And a charge relay 162 controlled to flow a current through the charge resistor R1 until a predetermined amount of voltage is charged in the DC-link capacitor C1.

Here, the power relay 165 is preferably a latch relay that maintains the switching state without supplying additional power. In order to maintain the on / off state of the general relay after the switching operation, the power supply must be continuously supplied, but the on / off state of the latch relay can be maintained even when power is not supplied after the switching operation.

In other words, the latch relay is a relay that uses the iron core having a large coercive force to keep the magnetic force even after the operation of the contact breaks the exciting current, and the contact is returned by the reverse excitation current.

The latch relay 165 has two coils (a set coil and a reset coil) in one relay. Since the set coil L1 has a resistance smaller than that of the reset coil L2, a large current flows, And the reset coil (L2), a larger current flows through the set coil (L1) and the magnetic force is strong, so that the relay can be set to the set state (ON state).

The control unit (Micom) 152 controls the inrush current prevention unit 160 so that the current flows between the first path through which the current flows through the charging resistor R1 and the second path through which the current flows through the power relay 162 Can be switched.

At this time, the control unit 152 may be manufactured using an integrated circuit such as a microcomputer (MICOM). DC power is supplied to the control unit 152, which will be described later.

When the power is initially turned on, the controller 152 turns on the charging relay 162 to control the current to flow through the charging resistor R1. Then, the supplied power is charged to the DC-link capacitor C via the rectifying part 110. [

Then, when the voltage charged in the DC-link capacitor C reaches the target value, the control unit 152 turns off the charge relay 162 and turns on the latch relay 165. [

Thereafter, when the power supply is interrupted, the control unit 152 turns off the latch relay 165 so that the overcurrent flows when the power supply is re-applied in the ON state of the latch relay 165, It is necessary to prevent it.

The current sensing unit 170 is connected between the inrush current prevention unit 160 and the rectification unit 110 to detect whether the AC power supply 10 is supplied to the rectification unit 110 .

The current sensing unit 170 senses the current supplied to the rectifying unit 110 and the sensing signal of the current sensing unit 170 is transmitted to the control unit 152. The control unit 152 receives the current from the current sensing unit 170, When the supply cutoff signal is received, a reset signal is applied to the reset coil L2 of the latch relay 165 so that the latch relay 165 is turned off.

The inrush current prevention unit 160 includes a first transistor T1 connected between the control unit 152 and the set coil L1 and a second transistor T1 connected between the control unit 152 and the reset coil L2. 2 < / RTI > transistor T2.

The first transistor T1 and the second transistor T2 serve as switches for amplifying the magnitude of the current from the controller 152 to each coil together with the buffer IC.

The rectifier 110, the converter 120, the DC-link capacitor C1 and the inverter 140 generate an AC power source. The AC power source 10, the second rectifier 180, A second DC-link capacitor C2, and a switched mode power supply (SMPS) 190 may be connected in parallel.

The rectifying unit 110 and the DC-link capacitor C1 may be referred to as a first rectifying unit 110 and a first DC-linking capacitor C1, and the second rectifying unit 180 and the second DC-linking capacitor C2 ).

The charging capacity of the first DC-link capacitor C1 is much greater than that of the second DC-link capacitor C2, so that the first DC-link voltage across the first DC- Can be discharged much longer during discharging than the second DC-link voltage across the capacitor C2.

Accordingly, the AC voltage output from the inverter 140 is about 100 to 400 V, whereas the DC voltage output from the SMPS 190 is about 5 to 10 V.

The DC voltage output from the SMPS 190 may be supplied to the circuit board or the LED display unit of the control unit driven by the low voltage power.

The control unit 152 receives the DC voltage output from the SMPS 190, and a DC power of 5 V is normally supplied to the control unit 152.

However, when the supply of the AC power source 10 is cut off due to a power failure or the like while the latch relay 165 is on, the power source of the SMPS 190 eventually comes from the AC power source 10 The control unit 152 may not be supplied with the power for applying the reset signal for turning off the latch relay 165 to the control unit 152. [

In order to prevent this, the first DC-link capacitor C1 and the second DC-link capacitor C2 are preferably connected by a bypass diode 185. [

The bypass diode 185 is a diode for giving a bypass to return the stored energy to the power source when the polarity of the power source changes in the rectifying circuit or the like and the energy stored in the inductance of the load circuit is to be emitted.

The bypass diode 185 prevents the current from flowing in the reverse direction, and when the potential difference between the both ends does not flow, the current flows only when a potential difference is generated between the both ends.

The DC-link voltages charged in the first DC-link capacitor C1 and the second DC-link capacitor C2 are equal to each other because the AC power supply 10 is the same, but when the supply of the AC power supply 10 is interrupted Since the capacity of the second DC-link capacitor C2 is smaller, the second DC-link voltage drops much faster than the first DC-link voltage.

Then, a potential difference is generated across the bypass diode 185, so that the voltage charged in the first DC-link capacitor C1 having a large capacitance is slowly discharged and the SMPS 190 supplies the control voltage to the control unit 152), DC power can be supplied for a long time.

Therefore, in a situation where the supply of AC power or the like is interrupted, the control unit 152 may apply a reset signal to the DC power supply via the bypass diode 185 and to turn off the latch relay 165.

4 is a flowchart showing the operation of a power conversion apparatus having an inrush current prevention function according to an embodiment of the present invention. 5 to 7 are circuit diagrams showing the operation of a power conversion apparatus having an inrush current prevention function according to an embodiment of the present invention.

Hereinafter, the operation of the power conversion apparatus having the inrush current prevention function according to the embodiment of the present invention will be described with reference to FIG. 4 to FIG.

First, when the power conversion apparatus does not operate, that is, when the air conditioner including the power conversion apparatus is not operating (hereinafter, referred to as a first mode), the inrush current prevention unit 160 State.

That is, the charge relay 162 is in an open state (off state) and the latch relay 165 is also in an open state (off state). At this time, since the first rectifying part 110 and the second rectifying part 180 are not connected to the AC power source 10, the first rectifying part 110 and the second rectifying part 180 do not operate.

Then, when the user plugs the plug of the air conditioner into the power outlet to turn on the input power (S10) and turns on the remote controller (S20), the state shown in Fig. 5 is obtained.

That is, the charging relay 162 is turned on, and the AC power source 10 is transmitted to the first rectifying part 110 through the charging resistor R1. Accordingly, power can be gradually charged to the first DC-link capacitor C1 through the first rectifying part 110 in a state where the voltage is reduced by the charging resistor R1 and the current is limited.

At this time, the latch relay 165 remains open.

Next, the control unit 152 determines whether the DC-link voltage charged in the first DC-link capacitor C1 has reached the target value (S40).

If the DC link voltage does not reach the target value even after a predetermined time has elapsed, the controller 152 may display an error on the display of the air conditioner (S50).

If the DC-link voltage reaches the target value within the predetermined time, the state shown in FIG. 6 is obtained.

That is, the control unit 152 turns off the charge relay 162 and turns on the latch relay 165 (S60).

Then, power is transmitted to the first DC-link capacitor C1 through the first rectifying part 110 via the latch relay 165. [

Thereafter, the control unit 152 determines whether the input power supply is blocked through the current sensing unit 170 (S70).

If the power supply is not interrupted, the air conditioner is normally operated normally (S80).

The controller 152 applies a reset signal to the reset coil 162 of the latch relay 165 to turn off the power relay 165 in step S90, . Then, the state shown in FIG. 7 is obtained.

That is, the latch relay 165 is turned off and the charging relay 162 is also turned off, and the state before the initial power-on is returned as in Fig.

At this time, the control unit 152 can operate the DC voltage charged in the first DC-link capacitor C1 via the bypass diode 185 via the SMPS 190.

According to the present invention, it is not necessary to supply power to maintain the switching state by using the latch relay with the power relay of the inrush current prevention portion, thereby reducing power consumption.

Further, in a situation where the power supply is cut off due to a power failure or the like in the latch relay on state, the SMPS 190 to the control unit 152 can be connected to the relay 152 via the bypass diode to connect the first DC- Can supply a direct current capable of switching.

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.

100: power conversion device 110: first rectification part
120: converter 130: converter control unit
140: inverter 150: inverter controller
131, 151: Gate driver 152:
160: Inrush current prevention part 162: Charge relay
165: Power relay 170: Current sensing unit
180: second rectifier 190: SMPS
200: motor

Claims (9)

A first rectifying section for rectifying an AC input from an AC power source;
A first DC-link capacitor charged with a DC voltage rectified by the rectifying unit;
A power relay connected between the AC power source and the first rectifying part and maintaining a switching state without additional power supply, a charging resistor connected in parallel with the power relay, and a charging relay connected in series with the charging resistor, part;
A current sensing unit connected between the inrush current preventing unit and the first rectifying unit to sense whether the AC power is supplied to the first rectifying unit; And
Controls the charging relay so that a current flows through the charging resistor until a predetermined amount of voltage is charged in the first DC-link capacitor, and when the power supply interruption is detected by the current sensing unit, the power relay is turned off Off) of the power supply voltage. The method according to claim 1,
Wherein the power relay is a latch relay. 3. The method of claim 2,
The latch relay includes:
A set coil to which a set signal for turning on the power relay is applied,
And a reset coil to which a reset signal for turning off the power relay is applied. The method of claim 3,
The inrush current prevention part includes:
A first transistor connected between the control unit and the set coil,
And a second transistor connected between the control unit and the reset coil. 5. The method of claim 4,
A second rectifying unit for rectifying an AC input from the AC power source;
A second DC-link capacitor charged with a DC voltage rectified by the second rectification part; And
And an SMPS coupled to the second DC-link capacitor,
Wherein the controller receives DC power from the SMPS. 6. The method of claim 5,
And the first DC-link capacitor and the second DC-link capacitor are connected by a bypass diode. The method according to claim 6,
When the charging voltage of the first DC-link capacitor reaches a target value within a predetermined time, the control unit transmits a Set signal to the latch relay to turn on the latch relay, (On), and then turns off the charging relay. 8. The method of claim 7,
Wherein the controller transmits a reset signal to the latch relay to turn off the latch relay when the current sensing unit detects that the power supply is interrupted. An air conditioner comprising the power conversion device according to any one of claims 1 to 8.

Images