KR102130591B1 - Power converting apparatus and home appliance including the same - Google Patents

Abstract

A power conversion apparatus and a home appliance according to an embodiment of the present invention include a reactor, a converter including a first switching element at the top connected to a leg, and a second switching element at the bottom, the first switching By including a voltage sensing unit for sensing the voltage across the device, a comparator for comparing the output of the voltage sensing unit with a reference voltage, and a control unit for controlling the switching operation of the first switching element and the second switching element based on the output of the comparator It is possible to perform the overcurrent determination and protection operation and to efficiently perform power factor compensation.

Description

Power converting apparatus and home appliance including the same

The present invention relates to a power conversion device and a home appliance having the same, and more particularly, to a power conversion device capable of efficiently performing power factor compensation and a home appliance having the same.

In general, electronic devices such as air conditioners are equipped with a power conversion device and operate by converting input power.

The air conditioner is installed to provide a more comfortable indoor environment to humans by discharging cold and warm air into the room to create a comfortable indoor environment, adjusting the indoor temperature, and purifying the indoor air. In general, an air conditioner includes an indoor unit installed inside a heat exchanger, and an outdoor unit configured with a compressor and a heat exchanger to supply refrigerant to the indoor unit.

The power conversion device is a device that converts input power and supplies converted power. Such a power conversion device is disposed in the home appliance, and can convert input power to power for driving the home appliance.

For example, the power conversion device may be disposed in an air conditioner to convert AC power to DC power to supply to a load or drive a motor.

Home appliances, such as air conditioners, often have a power factor correction (PFC) for converting reactive power into active power in consideration of the characteristics of the voltage before AC.

For example, the prior document 1 (Korean Patent Application Publication No. 10-2004-0020760, published date March 09, 2004) discloses the contents of the power factor compensation converter circuit of the inverter air conditioner.

These power factor compensation circuits usually use a single pulse or alternately switch a plurality of switching elements at high speed. However, when using a pulse, the reactor capacity must be extremely large and the input current waveform is poor, making it difficult to meet specifications such as harmonics and power factor. Also, when switching elements are alternately switched at a high speed of several tens of kHz. In order to minimize switching loss, an expensive semiconductor device having a high switching speed had to be used, and there was a problem in that the loss due to heat generation and heat generation increased in proportion to the switching.

An object of the present invention is to provide a power conversion device capable of performing an overcurrent determination and protection operation and a home appliance having the same.

An object of the present invention is to provide a power conversion device capable of efficiently performing power factor compensation and a home appliance having the same.

An object of the present invention is to provide a power conversion device capable of reducing switching loss and heat generation by controlling a converter through minimal switching and a home appliance having the same.

The power conversion apparatus and the home appliance according to an embodiment of the present invention for achieving the above object, one reactor, and a first switching element connected to a leg (leg) at the top and the second switching element at the bottom Included converter, a voltage sensing unit that senses the voltage across the first switching element, a comparator comparing the output of the voltage sensing unit with a reference voltage, and switching operations of the first switching element and the second switching element based on the output of the comparator By including a control unit for controlling the overcurrent determination and protection operation can be performed and power factor compensation can be performed efficiently.

According to at least one of the embodiments of the present invention, it is possible to perform an overcurrent determination and protection operation.

In addition, according to at least one of the embodiments of the present invention, power factor compensation can be efficiently performed.

In addition, according to at least one of the embodiments of the present invention, switching loss and heat generation can be reduced by controlling the converter through minimal switching.

Meanwhile, various other effects will be disclosed directly or implicitly in a detailed description according to an embodiment of the present invention to be described later.

1 is a view illustrating the configuration of an air conditioner according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of the outdoor unit and the indoor unit of FIG. 1.
3 is an example of a circuit diagram of a power conversion apparatus according to an embodiment of the present invention.
4 is an example of a circuit diagram of a power conversion apparatus according to an embodiment of the present invention.
5 is a view referred to for a description of a switching period according to an embodiment of the present invention.
6 to 9 are views referred to for a description of a switching operation of a power conversion device 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. However, it should be understood that the present invention is not limited to these embodiments and can be modified in various forms.

In the drawings, in order to clearly and briefly describe the present invention, illustration of parts irrelevant to the description is omitted, and the same reference numerals are used for the same or extremely similar parts throughout the specification.

On the other hand, the suffixes "module" and "part" for the components used in the following description are given merely considering the ease of writing the present specification, and do not impart a particularly important meaning or role in itself. Therefore, the "module" and the "unit" may be used interchangeably.

Further, in the present specification, terms such as first and second may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.

Meanwhile, the power conversion device described in this specification may be a power conversion device provided in a home appliance. The home appliance includes a refrigerator, a washing machine, a dryer, an air conditioner, a dehumidifier, a cooking appliance, a vacuum cleaner, and the like, and hereinafter, mainly describes air conditioners among various home appliances.

1 is a view illustrating the configuration of an air conditioner according to an embodiment of the present invention.

Referring to FIG. 1, the air conditioner 100 according to the present invention may include an indoor unit 21 and an outdoor unit 31 connected to the indoor unit 21.

The indoor unit 21 of the air conditioner may be any one of a stand type air conditioner, a wall-mounted air conditioner, and a ceiling type air conditioner, but in the drawing, the stand type indoor unit 21 is illustrated.

Meanwhile, the air conditioner 100 may further include at least one of a ventilation device, an air cleaning device, a humidifying device, and a heater, and may operate in conjunction with the operation of the indoor unit and the outdoor unit.

The outdoor unit 31 is a compressor (not shown) that receives and compresses refrigerant, an outdoor heat exchanger (not shown) that exchanges heat between the refrigerant and outdoor air, and an accumulator (not shown) that extracts gas refrigerant from the supplied refrigerant and supplies it to the compressor. City), and a four-way valve (not shown) for selecting the flow path of the refrigerant according to the heating operation. In addition, a plurality of sensors, valves, and an oil recovery device are further included, but a description of the configuration will be omitted below.

The outdoor unit 31 supplies a refrigerant to the indoor unit 21 by compressing or heat-exchanging the refrigerant according to the setting by operating the provided compressor and the outdoor heat exchanger. The outdoor unit 31 may be driven by a remote controller (not shown) or a demand of the indoor unit 21. At this time, as the cooling/heating capacity is changed corresponding to the driven indoor unit, it is possible that the number of operation of the outdoor unit and the number of operation of the compressor installed in the outdoor unit are variable. In addition, although one indoor unit 21 and an outdoor unit 31 are illustrated in FIG. 1, the present invention is not limited thereto. For example, several indoor units 21 may be connected to a single outdoor unit 31 by a refrigerant pipe.

At this time, the outdoor unit 31 supplies compressed refrigerant to the connected indoor unit 21.

The indoor unit (21) receives refrigerant from the outdoor unit (31) and discharges cold and warm air into the room. The indoor unit 21 includes an indoor heat exchanger (not shown), an indoor fan (not shown), an expansion valve (not shown) for expanding the supplied refrigerant, and a plurality of sensors (not shown).

At this time, the outdoor unit 31 and the indoor unit 21 are wired or wirelessly connected to transmit and receive mutual data, and the outdoor unit and the indoor unit are connected to a remote controller (not shown) or wired or wirelessly to control the remote controller (not shown). It can work accordingly.

The remote control (not shown) is connected to the indoor unit 21, and inputs a user's control command into the indoor unit, and receives and displays status information of the indoor unit. At this time, the remote control may communicate with wired or wireless depending on the type of connection with the indoor unit.

2 is a schematic view of the outdoor unit and the indoor unit of FIG. 1.

Referring to FIG. 2, the air conditioner 100 is largely divided into an indoor unit 21 and an outdoor unit 31.

The outdoor unit 31 includes a compressor 102 serving to compress the refrigerant, an electric motor 102b for driving the compressor, an outdoor heat exchanger 104 serving to dissipate the compressed refrigerant, and outdoor The outdoor blower 105, which is disposed on one side of the heat exchanger 104 and promotes heat dissipation of the refrigerant, and an outdoor fan 105 composed of a motor 105b that rotates the outdoor fan 105a, and expansion to expand the condensed refrigerant. Mechanism or expansion valve 106, a cooling/heating switching valve or four-way valve 110 for changing the flow path of the compressed refrigerant, and temporarily storing the vaporized refrigerant to remove moisture and foreign substances, and then cooling the refrigerant at a constant pressure to the compressor. And an accumulator 103 to be supplied.

The indoor unit 21 is disposed indoors to perform an air/heating function, and the indoor heat exchanger 108 and an indoor fan 109a disposed on one side of the indoor heat exchanger 108 to promote heat dissipation of the refrigerant and the indoor And an indoor blower 109 made of an electric motor 109b for rotating the fan 109a.

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

In addition, the air conditioner 100 may be configured with a cooler that cools the room, or may be configured with a heat pump that cools or heats the room.

Meanwhile, the outdoor fan 105a in the outdoor unit 31 may be driven by an outdoor fan driving unit (not shown) that drives the motor 105b.

Meanwhile, the compressor 102 in the outdoor unit 31 may be driven by a compressor motor driving unit (not shown) that drives the compressor motor 102b.

Meanwhile, the indoor fan 109a in the indoor unit 21 may be driven by an indoor fan driving unit (not shown) that drives the indoor fan motor 109b. The outdoor fan driving unit 200 may be referred to as an outdoor fan driving device. Also, an indoor fan driving unit (not shown) may be referred to as an indoor fan driving device.

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

Referring to FIG. 3, the power conversion device 400 according to an embodiment of the present invention converts an input power into a DC power and outputs it to a dc terminal, a converter 410, a converter controller 415, and the dc terminal. It includes a connected capacitor (C), a plurality of switching elements, and includes an inverter (420) for AC conversion of DC power from the capacitor (C), and an inverter control unit (430) for controlling the inverter (420) Can be. The power conversion device 400 may further include an input voltage detector A, a dc stage voltage detector B, an input current detector D, and an output current detector E.

Meanwhile, in FIG. 3 or less, an example in which the power conversion device 400 is used as a motor driving device that converts the power input from the commercial AC power supply 201 and supplies it to the motor 250 is provided. In this case, the power conversion device 400 may be referred to as a motor driving device, a motor driving unit, or the like. Alternatively, the power conversion device 400 may convert input power and supply it to a load. In FIG. 3, the power conversion device 400 is mainly described as an example implemented as a motor driving device, but the present invention is not limited thereto.

The converter 410 may convert and output the commercial AC power supply 201 to DC power. To this end, the converter 410 may include a rectifying unit (460 in FIG. 4). Besides, it is also possible to further include a reactor (L1 in Fig. 4).

A smoothing capacitor C is connected to the output terminal of the converter 410. The capacitor C may store power output from the converter 410. Since the power output from the converter 410 is a dc power source, it may be referred to as a dc stage capacitor.

The inverter 420 may output the converted AC power to the motor 250.

Referring to FIG. 3, the input voltage detector A can detect the input voltage Vs from the input AC power supply 201.

The input voltage detector A may include a resistance element, an OP AMP, and the like for voltage detection. The detected input voltage Vs is a pulsed discrete signal and can be applied to the inverter control unit 230.

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

The input current detection unit D can detect the input current is input from the commercial AC power supply 201. To this end, as the input current detector D, a current trnasformer (CT), a shunt resistor, or the like can be used. The detected input current is is a discrete signal in the form of a pulse, and may be input to the inverter control unit 430 for power consumption calculation.

Next, a capacitor C for storing or smoothing the power converted by the power in the converter 410 may be provided at an output terminal of the converter 410. At this time, both ends of the capacitor C may be referred to as a dc terminal. Therefore, the capacitor C may be referred to as a dc terminal capacitor.

Meanwhile, the converter control unit 415 generates a converter switching control signal Scc based on the input voltage Vs, the input current Is, and the dc terminal voltage Vdc, and outputs the converter switching control signal Scc to the converter 410. Can be.

The dc stage voltage detector B may detect the dc stage voltage Vdc at both ends of the smoothing capacitor C. To this end, the dc stage voltage detector B may include a resistance element, an amplifier, and the like. The detected dc terminal voltage (Vdc) is a discrete signal in the form of a pulse and may be input to the inverter control unit 430.

The inverter 420 may drive the motor 250. To this end, the inverter 420 includes a plurality of inverter switching elements, and converts the DC power supply (Vdc) smoothed by the on/off operation of the switching elements into three-phase AC power of a predetermined frequency, thereby providing a three-phase synchronous motor (250). ).

In the inverter 420, the upper arm switching element and the lower arm switching element that are connected in series with each other are paired, and a total of three pairs of upper and lower arm switching elements are connected in parallel with each other. A diode is connected in reverse parallel to each switching element.

The switching elements in the inverter 420 operate on/off of each switching element based on the inverter switching control signal Sic from the inverter control unit 430. Accordingly, the three-phase AC power having a predetermined frequency is output to the three-phase synchronous motor 250.

The inverter controller 430 may control the switching operation of the inverter 420. To this end, the inverter control unit 430 may receive the output current i _o detected by the output current detection unit E.

In order to control the switching operation of the inverter 420, the inverter control unit 430 outputs the inverter switching control signal Sic to the inverter 420. The inverter switching control signal Sic is a pulse width modulation method (PWM) switching control signal, which is generated and output based on the output current value i _o detected by the output current detection unit E.

The output current detector E detects the output current i _o flowing between the inverter 420 and the three-phase motor 250. That is, the current flowing through the motor 250 is detected. The output current detector E can detect all of the output currents ia, ib, and ic of each phase, or may detect the output currents of two phases by using three-phase balance.

The output current detection unit E may be located between the inverter 420 and the motor 250, and for current detection, a current trnasformer (CT), a shunt resistor, or the like can be used.

When a shunt resistor is used, it is possible that three shunt resistors are located between the inverter 420 and the synchronous motor 250, or one end is respectively connected to the three lower arm switching elements of the inverter 420. On the other hand, it is also possible to use two shunt resistors using three-phase equilibrium. On the other hand, when one shunt resistor is used, it is also possible that the shunt resistor is disposed between the above-described capacitor C and the inverter 420.

The detected output current (i _o ) is a discrete signal in the form of a pulse, and can be applied to the inverter control unit 430, and the inverter switching control signal (Sic) based on the detected output current (i _o ) Is created.

Meanwhile, the motor 250 may be a three-phase motor. The motor 250 is provided with a stator and a rotor, and AC power of a predetermined frequency is applied to the coils of the stators of each phase (a, b, and c), so that the rotor rotates. .

Such a motor 250 is, for example, a surface-mounted permanent magnet synchronous motor (Surface-Mounted Permanent-Magnet Synchronous Motor; SMPMSM), an embedded permanent magnet synchronous motor (Interior Permanent Magnet Synchronous Motor; IPMSM), and a synchronous reel And a Synchronous Reluctance Motor (Synrm). Among them, SMPMSM and IPMSM are Permanent Magnet Synchronous Motor (PMSM), and Synrm has no permanent magnet.

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

3 and 4, a power conversion device and a home appliance having the same according to an embodiment of the present invention include one reactor (L1) and a first switch at the top connected to one leg A converter 410 including an element S1 and a second switching element S2 at the bottom may be included.

In addition, the power conversion device according to an embodiment of the present invention and a home appliance having the same, the output of the voltage detection unit 441 and the voltage detection unit 441 to detect the voltage across the first switching element (S1) An overcurrent by including a comparator 442 comparing with a reference voltage and a control unit 415a for controlling the switching operation of the first switching element S1 and the second switching element S2 based on the output of the comparator 442 Judgment and protection operations can be performed and power factor compensation can be efficiently performed.

According to an embodiment, the control unit 415a may be a micom for performing an overcurrent determination and protection operation.

More preferably, the control unit 415a may be a converter control unit 415 capable of controlling the overall operation of the converter 410, including overcurrent determination and protection operation. Accordingly, a separate additional configuration is minimized, and the converter 410 can be controlled most efficiently.

Hereinafter, the converter control unit 415 includes a voltage sensing unit 441 sensing the voltage across the first switching element S1 and a comparator 442 comparing the output of the voltage sensing unit 441 with a reference voltage. A description will be given of an embodiment in which switching operations of the first switching element S1 and the second switching element S2 are controlled based on the output of the overcurrent determination unit 440.

The power conversion apparatus and the home appliance having the same according to an embodiment of the present invention may further include a shunt resistor R1 connected to the second switching element S2. Of the two switches (S1, S2) configured in one leg, the current sensing and overcurrent are determined using the shunt resistor R1 applied to the lower second switching element S2, and the protection circuit is determined. can do.

On the other hand, according to an embodiment of the present invention, there is a section in which current flows only in the first switching element S1 among the first switching element S1 and the second switching element S2.

Therefore, there is a possibility that a current conduction path in which an overcurrent flows only to the upper first switching element S1, and in this case, since the overcurrent does not pass through the shunt resistor R1, it is impossible to determine the overcurrent and thus the possibility of component burnout is very high.

Therefore, the power conversion apparatus according to the present invention, the overcurrent determination unit 440 for determining the overcurrent of the upper first switching element (S1) by using the Vce (sat (sat (sat)) characteristic of the upper first switching element (S1) It may be provided.

The overcurrent determining unit 440 may include a voltage sensing unit 441 sensing voltage across both ends of the upper first switching element S1 and a comparator 442 comparing the output of the voltage sensing unit 441 with a reference voltage. have.

The Vce(sat) value of the switching element has different characteristics according to the value of the current flowing through the collector-emitter.

A voltage detector 441 that senses the voltage at both ends of the upper first switching element S1 by using these characteristics, and a comparator 442 that sets a value of Vce(sat) when an overcurrent flows as a reference voltage (Reference) It can be determined whether or not the overcurrent.

If it is determined as overcurrent, the converter control unit 415 stops switching and enters a protection operation.

Therefore, since it is possible to determine the overcurrent flowing through the upper first switching element S1, it is possible to prevent circuit damage due to overcurrent, thereby ensuring system stability.

The voltage detector 441 senses the voltage across the collector-emitter of the upper first switching element S1 in real time.

The comparator 442 operates when the output of the voltage sensing unit 441 is equal to or higher than the Vce(sat) reference voltage value of the preset overcurrent level (Level).

There is also a method of detecting a current through a CT sensor by disposing a CT (Current Transformer) sensor in the power supply terminal, but due to the impedance (L) characteristic of the CT sensor transformer, a delay occurs when sensing the current.

Therefore, the present invention can further improve the stability of the system by directly detecting an overcurrent through the voltage across both ends of the upper first switching element S1 through the voltage detector 441 and performing a protection operation.

According to an embodiment, the voltage detector 441 may amplify and output a voltage across the collector-emitter of the upper first switching element S1 to facilitate voltage comparison. In this case, the reference voltage may also be set in consideration of the amplified voltage across both ends.

Meanwhile, the output of the comparator 442 is transmitted to the microcomputer 415a or the converter control unit 415.

The microcomputer 415a or the converter control unit 415 operates the protection logic based on the output of the comparator 442. For example, the microcomputer 415a or the converter control unit 415 may stop the PWM output of the upper first switching element S1 and the lower second switching element S2 to prevent component burnout.

The converter 410 includes a plurality of diodes (D1a, D1b, D2a, D2b) rectifying unit 460 for rectifying input AC power, and disposed between the input AC power 201 and the rectifying unit 460 It may include a power factor compensation unit 450.

The power factor compensator 450 may make the input current a sinusoidal wave to compensate the power factor and remove harmonics.

The power factor compensator 450 may include one reactor L1 and two switching elements S1 and S2, and compensate power factor of the AC power. The reactor L1 stores energy and, by switching of the two switching elements S1 and S2, energy is charged and discharged in the reactor L1, thereby improving the input current waveform.

At this time, the power factor compensation control may be performed by the control signal of the converter control unit 415. For example, the converter control unit 415 may turn the power factor compensation control function on or off by controlling the switching operation of the switching elements S1 and S2.

The converter 410 may compensate the power factor for the supplied power while converting the input AC power to DC power.

The converter 410 may convert AC power into DC power, and output the converted DC power. The smoothing capacitor C may smooth and store the output power of the converter 410.

To this end, the converter 410 may include a rectifying unit 460 to output rectified power by rectifying the input AC power.

For example, the rectifier 460 may include two diodes connected to one leg. In addition, the rectifying unit 460 according to an embodiment of the present invention may be composed of a first diode (D1a, D1b) and a second diode (D2a, D2b) in which a pair of diodes are connected in parallel. Accordingly, it is possible to use twice the rated current and to cope with higher rated currents, thereby improving circuit safety.

5 is a view referred to for a description of a switching section according to an embodiment of the present invention, and illustrates switching operations of the input voltage Vin, the input current Iin, and the switching elements S1 and S2 for each section. .

6 to 9 are views for reference to a description of a switching operation of a power conversion device according to an embodiment of the present invention, and show current paths when switching elements S1 and S2 are on and off.

Referring to the drawings, the power factor compensator 450 may include one reactor L1 and two switching elements S1 and S2, and compensate power factor of the AC power.

The switching elements S1 and S2 may be composed of a semiconductor element and a free wheeling diode. For example, the switching elements S1 and S2 may be composed of a pair of an insulated gate bipolar transistor (IGBT) and a free wheeling diode, respectively.

The reactor L1 stores energy and, by switching of the two switching elements S1 and S2, energy is charged and discharged in the reactor L1, thereby improving the input current waveform.

The power factor compensator 450 includes a first switching element S1 and a second switching element S2 arranged in series, and the reactor L1 includes a first switching element S1 and a second switching It may be connected to a node between the elements (S2). That is, the first switching element (S1) and the second switching element (S2) are disposed at the top and the bottom of each leg, and are connected to the first switching element (S1) at the top and the second switching element (S2) at the bottom. To the reactor (L1) is connected.

Also, the first switching element S1 at the top and the second switching element S2 at the bottom may be connected to the rectifier 460, respectively.

Referring to FIG. 4, the upper first switching element S1 may be disposed between the reactor L1 and the rectifier 460. More specifically, the upper first switching element S1 may be connected to the upper first diodes D1a and D1b. The lower first switching element S2 may be disposed between the reactor L1 and the rectifier 460. More specifically, the lower first switching element S2 may be connected to the lower second diodes D2a and D2b.

That is, one end of the first switching element S1 and the second switching element S2 of the lower end may be connected to the reactor L1, and the other end may be connected to the rectifier 460.

In addition, an output terminal may be configured at a node connection point between the first switching element S1 at the top and the second switching element S2 at the bottom.

Meanwhile, the power factor compensation control may be performed by a control signal from the converter control unit 415. For example, the converter control unit 415 may turn the power factor compensation control function on or off by controlling the switching operation of the switching elements S1 and S2.

According to an embodiment, the power conversion device further includes an input voltage detection unit A for detecting the input voltage, and the converter control unit 415 switches the switching element S1 according to the input voltage detected by the input voltage detection unit A. , S2) the turn on / off timing can be controlled.

Meanwhile, the converter control unit 415 may output a converter switching control signal for turn on/off timing of the switching elements S1 and S2. The converter switching control signal is a pulse width modulation (PWM) switching control signal and may be a signal for controlling the duty ratios of the switching elements S1 and S2.

The converter control unit 415 may vary the duty ratios of the switching elements S1 and S2 according to the load. For example, the higher the load, the higher the duty ratio can be.

In addition, the converter control unit 415 may vary the number of switching times of the switching elements S1 and S2 according to the load. For example, the higher the load, the greater the number of switching times.

According to the present invention, the switching elements (S1, S2), the switching period is set before and after the rest period (T4, T8 (T0)) including a zero crossing point of the input voltage from the input AC power supply 201 ( T3, T5, T7, T1).

Referring to FIG. 5, any one of the switching elements S1 and S2 may be switched in a switching period T3 set in front and a switching period T5 set in the center around a predetermined rest period T4.

In addition, any one of the switching elements S1 and S2 may be switched in the switching period T7 set in the front and the switching period T1 set in the rear with respect to the predetermined rest period T8(T0).

In this way, the two switching elements (S1, S2) between the switching period (T3, T5, T7, T1) do not switch the rest period (T4, T8 (T0)) is set by being connected to one leg The upper/lower switching elements S1 and S2 are turned on at the same time, so that arm-short can be prevented and over-current caused by the arm-short can be prevented.

In addition, by controlling the switching operation of the switching elements (S1, S2) based on the zero crossing point, it is possible to switch the switching elements (S1, S2) at the correct timing.

According to a power factor improvement method that is widely used in the related art, power factor is improved by performing switching in all sections to generate a sine wave input current similar to the input voltage.

In this case, since switching is performed in all sections, the number of switching times is very high, and there is a problem in that heat generation and switching loss also increase.

In addition, conventionally, two switches were switched at a high speed at a frequency of several tens of kHz. For this, an expensive switching component with a fast switching time must be used, and component heating by high-speed switching may also affect drive reliability.

However, according to the present invention, by setting the switching period and the rest period rather than the entire period, the switching operation is performed only in the switching period, which is a partial period, thereby minimizing the number of switching to minimize heat generation and loss.

According to the present invention, by switching only a few times before/after zero crossing, the waveform of the input current can be improved with minimal switching to satisfy power factor and harmonics.

According to the present invention, circuit configuration and control are simple, and drive efficiency can be increased by minimizing switching loss and heat generation.

According to an embodiment of the present invention, according to the polarity of the input voltage Vin in the switching periods T3, T5, T7, T1, only one switching element among the two switching elements S1, S2 It can be controlled to be switched.

Referring to FIG. 5, the first switching element S1 switches in a section in which the input voltage Vin is negative (-), and the second switching element S2 has a positive (input voltage) Vin. +).

5 and 6, when the second switching element S2 is turned on in the switching periods T1 and T3 in which the input voltage Vin is positive (+), the reactor L1 is turned on. , A current path may be formed in the second diode order (D2a, D2b) of the rectifying part 460 connected to the second switching element S2 and the second switching element S2.

In this case, the converter control unit 415 may control to determine whether or not the overcurrent is based on the current sensed through the shunt resistor R1 and perform a protection operation.

5 and 7, in the switching periods T1 and T3 where the input voltage Vin is positive (+), when the second switching element S2 is off, the reactor L1 is turned off. , Free wheeling diode of the first switching element (S1), the smoothing capacitor (C), the second diode sequence (D2a) of the rectifier 460 connected to the second switching element (S2) (D2a, A current path may be formed with D2b).

By switching the lower second switching element S2 several times in the sections T1 and T3 where the input voltage Vin is a positive (+) half period, the waveform of the input current Iin is improved.

When the second switching element S2 is turned on, the reactor L1 is charged, and when the second switching element S2 is turned off, the reactor L1 is discharged and the input voltage vin and the reactor are discharged. (Reactor) The current flows into the load by the sum of the voltages, thereby improving the waveform of the input current (Iin).

In this case, the converter control unit 415 may control to determine whether an overcurrent is present and perform a protection operation based on the output of the overcurrent determination unit 440.

5 and 8, in the switching periods T5 and T7 in which the input voltage Vin is negative (-), when the first switching element S1 is turned on, the first switching element A current path may be formed in the order of the first diodes D1a and D1b of the rectifier 460 connected to (S1), the first switching element S1, and the reactor L1.

In this case, the converter control unit 415 may control to determine whether an overcurrent is present and perform a protection operation based on the output of the overcurrent determination unit 440.

5 and 9, in the switching periods T5 and T7 in which the input voltage Vin is negative (-), when the first switching element S1 is off, the first switching element The current passes in the order of the first diodes D1a and D1b of the rectifier 460 connected to (S1), the smoothing capacitor C, the freewheeling diode of the second switching element S2, and the reactor L1. Can be formed.

In this case, the converter control unit 415 may control to determine whether or not the overcurrent is based on the current sensed through the shunt resistor R1 and perform a protection operation.

In the periods T5 and T7 in which the input voltage Vin is a negative half period, the first switching element S1 switches while the input voltage Vin is a positive (+) half period (T1, T3). And complementary progress.

In the period (T5, T7) in which the input voltage Vin is a negative half-cycle, when the upper first switching element S1 is On, the reactor L1 is charged, and when it is Off, the reactor As (L1) is discharged, a current flows to the load by the sum of the input voltage (vin) and the reactor voltage, and the waveform of the input current (Iin) is improved.

In addition, according to the present invention, switching loss and heat generation of the switching element are improved since minimal switching is performed compared to a PFC mode in which high-speed switching is performed.

On the other hand, the converter control unit 415, the third section (T3) and the fifth section (T5), the seventh section (T7) and the switching period corresponding to the first section (T1) of the next period of the upper / lower end The switching period of the first and second switching elements S1 and S2 may be set as a rest period to stop switching.

Accordingly, it is possible to prevent the upper/lower switching elements S1 and S2 from being turned on at the same time, thereby preventing over-current caused by arm-short and arm-short.

In addition, the converter control unit 415 may detect the input voltage and load in real time, and set the duty and the number of switching times of each switching section.

For example, the higher the load, the more the DC link is used to widen the operation area, and for stable operation, voltage boosting through switching is performed a lot. Therefore, the converter control unit 415, the higher the load, the duty (Duty) and the number of switching can be increased.

The power conversion device and the home appliance having the same according to the present invention are not limited to the configuration and method of the above-described embodiments, and the above embodiments are all of the embodiments so that various modifications can be made. Alternatively, a part may be selectively combined and configured.

In addition, although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the technical field to which the present invention pertains without departing from the gist of the present invention claimed in the claims. In addition, various modifications can be implemented by those skilled in the art, and these modifications should not be individually understood from the technical idea or prospect of the present invention.

Converter: 410
Converter control unit: 415
Inverter: 420
Inverter control unit: 430
Power factor compensation unit: 510, 610
Rectification part: 520, 620

Claims (10)

A converter including a rectifier including a plurality of diodes to rectify an input AC power, a reactor, and a first switching element at the top and a second switching element at the bottom connected to one leg;
A smoothing capacitor that smooths and stores the output power of the converter;
A voltage sensing unit that senses voltage across both ends of the first switching element;
A shunt resistor connected to the second switching element;
A comparator comparing the output of the voltage sensing unit with a reference voltage; And,
It includes; a control unit for controlling the switching operation of the first switching element and the second switching element based on the output of the comparator;
Switching any one of the first switching element and the second switching element according to the polarity of the input voltage in the switching period set before and after the rest period including the zero crossing point of the input voltage from the input AC power source. Power conversion device characterized in that only the elements are switched. delete According to claim 1,
The reactor is connected to a node between the first switching element and the second switching element,
The first switching element switches in a section in which the input voltage is negative (-),
The second switching element is a power conversion device characterized in that the input voltage is switched in a positive (+) section. delete According to claim 1,
In the switching period in which the input voltage is negative (-), when the first switching element is turned on, in order of the first diode, the first switching element, and the reactor of the rectifier connected to the first switching element. Power conversion device characterized in that the current path is formed. According to claim 1,
In the switching period in which the input voltage is negative (-), when the first switching element is off, the first diode, the smoothing capacitor, and the second switching element of the rectifier connected to the first switching element are Power conversion device, characterized in that the current path is formed in the order of the freewheeling diode, the reactor. According to claim 1,
In the switching period in which the input voltage is positive (+), when the second switching element is turned on, in order of the second diode of the rectifier connected to the reactor, the second switching element, and the second switching element. Power conversion device characterized in that the current path is formed. According to claim 1,
In the switching period in which the input voltage is positive (+), when the second switching element is off, the reactor, the freewheeling diode of the first switching element, the smoothing capacitor, and the second switching element are connected Power conversion device characterized in that the current path is formed in the order of the second diode of the rectifying unit. delete Home appliances characterized in that it comprises a; power conversion device of any one of claims 1, 3, 5 to 8.

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