KR20170011612A - Power converting apparatus and air conditioner including the same - Google Patents

Abstract

The present invention relates to a power conversion apparatus and an air conditioner having the same. According to an embodiment of the present invention, the power conversion apparatus comprises: a converter having a switching element, and converting input alternating current power into direct current power to output the power; and a control unit for controlling the converter. The control unit divides a half period of the input power into a plurality of sections, and controls the switching element in the converter to be separately driven for first and second sections having a first switching frequency, and a third section between the first and second sections, having a second switching frequency lower than the first switching frequency. Therefore, the efficiency of the converter can be increased.

Description

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

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power conversion apparatus and an air conditioner having the same, and more particularly, to a power conversion apparatus capable of increasing converter efficiency and an air conditioner having the same.

The air conditioner is installed to provide a comfortable indoor environment for humans by discharging cold air to the room to adjust the room temperature and purify the room air to create a pleasant indoor environment. Generally, the air conditioner includes an indoor unit which is constituted by a heat exchanger and installed in a room, and an outdoor unit which is constituted by a compressor, a heat exchanger and the like and supplies the refrigerant to the indoor unit.

On the other hand, current large-capacity air conditioners rectify the input three-phase voltage using a diode, which is a passive element, and drive the motor through the inverter using the rectified voltage. In this case, as the load connected to the inverter increases, the dc step voltage decreases. Particularly, when the motor rotates at a high speed, the shortage of the dc step voltage tends to cause a restriction of high speed operation.

It is an object of the present invention to provide a power conversion device capable of increasing converter efficiency and an air conditioner having the power conversion device.

According to an aspect of the present invention, there is provided a power conversion apparatus comprising: a converter having a switching device and converting an input AC power to DC power and outputting the DC power; and a controller for controlling the converter, A half period of the input power source is divided into a plurality of sections and a first section and a second section having a first switching frequency and a third section having a second switching frequency lower than the first switching frequency, And controls the switching elements in the converter to be driven.

According to another aspect of the present invention, there is provided an air conditioner including a switching device, a converter for converting an input AC power to a DC power and outputting the DC power, and a controller for controlling the converter, A first and a second section having a first switching frequency, and a third section having a second switching frequency lower than the first switching frequency, the first and second sections having a first switching frequency, And controls the switching elements in the converter so as to be divided into the sections.

According to an embodiment of the present invention, there is provided a power conversion apparatus and an air conditioner having the same, the power conversion apparatus including a switching element, a converter for converting an input AC power into a DC power and outputting the DC power and a control unit for controlling the converter, A first and a second section having a first switching frequency and a second section having a second switching frequency lower than the first switching frequency by dividing a half period of the input power source into a plurality of sections, The switching and conduction loss of the converter switching element can be reduced by controlling the switching elements in the converter so as to be driven by the three sections. As a result, the converter efficiency can be increased.

On the other hand, the converter control unit controls the second switching frequency to be higher as the load of the output end of the converter becomes larger, controls the interval width between the first interval and the second interval to be smaller, or increases the interval width of the third interval It is possible to control the magnitude of the current ripple flowing in the converter to be small so that switching and conduction loss of the converter switching element can be reduced and consequently the converter efficiency can be increased.

1 is a diagram illustrating a configuration of an air conditioner according to an embodiment of the present invention.
2 is a schematic view of the outdoor unit and the indoor unit of FIG.
3 is a block diagram of a power converter for driving a compressor in the outdoor unit of FIG.
4 is an example of a circuit diagram of the power conversion apparatus of Fig.
5 is an example of an internal block diagram of the converter control unit of Fig.
6 to 10B are diagrams referred to in the description of the operation of the converter control unit of FIG.
11 is another example of a circuit diagram of the power conversion apparatus of Fig.
12 is an example of an internal block diagram of the inverter control unit of FIG.

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

The suffix "module" and " part "for components used in the following description are given merely for convenience of description, and do not give special significance or role in themselves. Accordingly, the terms "module" and "part" may be used interchangeably.

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

The air conditioner 100 according to the present invention may include an indoor unit 31 and an outdoor unit 21 connected to the indoor unit 31 as shown in FIG.

The indoor unit 31 of the air conditioner is applicable to any of the stand-type air conditioner, the wall-mounted air conditioner, and the ceiling type air conditioner, but the stand type indoor unit 31 is exemplified in the figure.

Meanwhile, the air conditioner 100 may further include at least one of a ventilator, an air purifier, a humidifier, and a heater, and may operate in conjunction with the operation of the indoor unit and the outdoor unit.

The outdoor unit 21 includes a compressor (not shown) that receives refrigerant and compresses the refrigerant, an outdoor heat exchanger (not shown) that exchanges heat between the refrigerant and outdoor air, an accumulator that extracts the gas refrigerant from the supplied refrigerant, And a four-way valve (not shown) for selecting the flow path of the refrigerant according to the heating operation. In addition, a number of sensors, valves, oil recovery devices, and the like are further included, but a description thereof will be omitted below.

The outdoor unit (21) operates the compressor and the outdoor heat exchanger to compress or heat-exchange the refrigerant according to the setting to supply the refrigerant to the indoor unit (31). The outdoor unit 21 can be driven by a demand of a remote controller (not shown) or the indoor unit 31. At this time, as the cooling / heating capacity is changed corresponding to the indoor unit to be driven, the number of operation of the outdoor unit and the number of operation of the compressor installed in the outdoor unit can be varied.

At this time, the outdoor unit 21 supplies the compressed refrigerant to the indoor unit 310 connected thereto.

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

At this time, the outdoor unit 21 and the indoor unit 31 are connected to each other via a communication line to transmit and receive data. The outdoor unit and the indoor unit are connected to a remote controller (not shown) by wire or wireless, can do.

The remote controller (not shown) is connected to the indoor unit 31, and inputs a control command of the user to the indoor unit, and receives and displays the status information of the indoor unit. At this time, the remote controller can communicate by wire or wireless according to the connection form with the indoor unit.

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

Referring to the drawings, an air conditioner 100 is roughly divided into an indoor unit 31 and an outdoor unit 21.

The outdoor unit 21 includes a compressor 102 for compressing the refrigerant, a compressor 102b for driving the compressor, an outdoor heat exchanger 104 serving to dissipate the compressed refrigerant, An outdoor fan 105 which is disposed at one side of the heat exchanger 104 and includes an outdoor fan 105a for accelerating the heat radiation of the refrigerant and an electric motor 105b for rotating the outdoor fan 105a and an outdoor fan 105 for expanding the condensed refrigerant An accumulator 103 for temporarily storing the gasified refrigerant to remove moisture and foreign substances, and then supplying a refrigerant with a predetermined pressure to the compressor, a compressor 106 for compressing the refrigerant, a cooling / heating switching valve 110 for changing the flow path of the compressed refrigerant, And the like.

The indoor unit 31 includes an indoor heat exchanger 109 disposed inside the room and performing a cooling / heating function, an indoor fan 109a disposed at one side of the indoor heat exchanger 109 for promoting heat radiation of the refrigerant, And an indoor air blower 109 composed of an electric motor 109b for rotating the fan 109a.

At least one indoor heat exchanger 109 may be installed. At least one of an inverter compressor and a constant speed compressor may be used as the compressor 102. [

Further, the air conditioner 100 may be constituted by a cooling unit that cools the room, or a heat pump that cools or heats the room.

The compressor 102 in the outdoor unit 21 of Fig. 1 can be driven by a power converter (200 in Fig. 3) for driving the compressor, which drives the compressor motor 250. [

FIG. 3 is a block diagram of a power conversion apparatus for driving a compressor in the outdoor unit of FIG. 1, and FIG. 4 is an example of a circuit diagram of the power conversion apparatus of FIG.

3) includes a inverter 220 for outputting a three-phase AC current to the compressor motor 250, an inverter controller 230 for controlling the inverter 220, A converter 210 for supplying DC power to the inverter 220, a converter control unit 215 for controlling the converter 210, and a dc-stage capacitor C between the converter 210 and the inverter 220 . The compressor motor driving apparatus 200 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 power conversion apparatus 200 receives the AC power from the system, converts the power, and supplies the converted power to the compressor motor 250. Accordingly, the power conversion apparatus 200 may be referred to as a compressor driving apparatus.

Meanwhile, the power conversion apparatus 200 according to an embodiment of the present invention divides a half period into a plurality of sections according to the level or phase of the input AC power, The switching frequency of the device is variable. Thereby, switching and conduction loss of the converter switching element can be reduced, and consequently, the efficiency of the converter can be increased.

The converter 210 converts the input AC power supply to DC power supply. The converter 210 may be a concept including a rectifier 410 and a boost converter 420. On the other hand, the input power based on the input AC power can be named Pgrid.

The rectifying unit 410 receives the single-phase AC power source 201 and rectifies it to output rectified power.

To this end, the rectifying part 410 is formed by pairing the upper and lower laminated diode elements Da and Db and the lower arm diode elements D'a and D'b, which are connected in series to each other, and two pairs of upper and lower arm diode elements Are connected to each other in parallel (Da & D & a, Db & D'b). That is, they can be connected to each other in the form of a bridge.

The boost converter 420 includes an inductor L1 and a diode D1 connected in series to each other and a switching element S1 connected between the inductor L1 and the diode D1 between the rectifying part 410 and the inverter 220. [ . The energy stored in the inductor L1 can be output by turning off the switching element S1 and the energy stored in the inductor L1 can be output via the diode D1 by turning off the switching element S1 .

On the other hand, when the low-capacity dc single capacitor C is used, the boost converter 420 may output a voltage in which the constant voltage is boosted, that is, offset.

The converter control unit 215 can control the turn-on timing of the switching element S1 in the boost converter 420. [ Thus, the converter switching control signal Scc for turning-on timing of the switching element S1 can be output.

The converter control unit 215 receives the input voltage Vs and the input current Is from the input voltage detection unit A, the input current detection unit B and the dc voltage detection unit B, And can receive the voltage Vdc.

The input voltage detecting section A can detect the input voltage Vs from the input AC power supply 201. [ For example, at the front end of the rectifying part 410. [

The input voltage detecting unit 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 215 for generation of the converter switching control signal Scc as a discrete signal in the form of a pulse.

On the other hand, the input voltage detecting section A can also detect the zero crossing point of the input voltage.

Next, the input current detection section D can detect the input current Is from the input AC power source 201. [ Specifically, it can be positioned at the front end of the rectifying part 410. [

The input current detection unit D may include a current sensor, a current transformer (CT), a shunt resistor, or the like, for current detection. The detected input voltage Is may be applied to the converter control unit 215 to generate a converter switching control signal Scc as a discrete signal in the form of a pulse.

The dc voltage detecting unit B detects both ends of the dc short capacitor C, i.e., the dc short voltage Vdc. For power detection, a resistance element, OP AMP, or the like can be used. The detected voltage Vdc of the dc short-circuit capacitor C may be applied to the converter control unit 215 and the inverter control unit 230 as a discrete signal in the form of a pulse, The converter switching control signal Scc and the inverter switching control signal Sic can be respectively generated based on the DC voltage Vdc.

The inverter 220 includes a plurality of inverter switching elements and converts the smoothed direct current power supply Vdc into a three-phase alternating current power having a predetermined frequency by the on / off operation of the switching element, .

Accordingly, the inverter 220 can supply the inverter power (Pinv) to the motor 250 as a load. The inverter power Pinv at this time can follow the required target power as the power required by the motor 250 as a load. Therefore, in the present specification, the inverter power (Pinv) may be described by the same concept as the target power required at the load.

More specifically, the inverter 220 may include a plurality of switching elements. For example, the upper arm switching elements Sa, Sb, Sc and the lower arm switching elements S'a, S'b, S'c are connected in series to each other and a total of three pairs of upper and lower arm switching elements Can be connected to each other in parallel (Sa & S'a, Sb & S'b, Sc & S'c). Diodes may be connected in anti-parallel to each switching element Sa, S'a, Sb, S'b, Sc, S'c.

The inverter control unit 230 can output the inverter switching control signal Sic to the inverter 220 in order to control the switching operation of the inverter 220. [ The inverter switching control signal (Sic) is based on a switching control signal of a pulse width modulation (PWM), the motor output current flowing through the (250) (i _o) and a dc terminal capacitor ends the dc terminal voltage (Vdc), generated And output. The output current i _{o at} this time can be detected from the output current detection unit E and the dc short voltage Vdc can be detected from the dc short voltage detection unit B. [

The output current detection section E can detect the output current i _o flowing between the inverter 420 and the motor 250. [ That is, the current flowing in the motor 250 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 detector E may be located between the inverter 220 and the motor 250. For current detection, a current transformer (CT), a shunt resistor, or the like may be used.

The inverter control unit 230 may include a current command generator (330 in FIG. 12), a voltage command generator (340 in FIG. 12), and a switching control signal output unit (360 in FIG. 12). This will be described in more detail with reference to FIG. 12 and the following figures.

The output inverter switching control signal Sic may be converted into a gate driving signal in a gate driver (not shown) and input to the gate of each switching element in the inverter 220. [ As a result, the switching elements Sa, S'a, Sb, S'b, Sc, and S'c in the inverter 220 perform the switching operation.

5 is an example of an internal block diagram of the converter control unit of Fig.

Referring to the drawing, the converter controller 215 may include a current command generator 720, a current controller 730, and a deflector 740.

The current command generation section 720 can generate the current command value I ^* by synchronizing the phase and shape of the input voltage. To this end, the current command generator 720 may include a computing unit 725, a voltage controller 727, and an input voltage compensating unit 729.

The computing unit 725 calculates the difference between the dc step voltage command value V ^* dc and the dc step voltage Vdc detected by the dc step voltage detecting unit B and transmits the difference to the voltage controller 727 .

The voltage controller 727 can generate the current command value through the PI control or the like based on the difference between the dc step voltage command value V ^* dc and the detected dc step voltage Vdc.

On the other hand, the input voltage compensating unit 729 can generate the compensation current command value for compensating the input voltage in consideration of the phase and the shape of the input AC power supply Vs. For example, it is possible to output the compensation current command value of | sin? T |.

On the other hand, the computing unit 728 can generate and output the final current command value based on the current command value from the voltage controller 727 and the compensation current command value from the input voltage compensating unit 729. [

For example, the calculator 728 can multiply the current command value from the voltage controller 727 by the compensation current command value (| sin? T |) and output it. Accordingly, the phase component can be reflected.

As a result, the current command generation section 720 finally generates the current command value I ^* based on the current command value from the voltage controller 727 and the compensation current command value from the input voltage compensation section 729 Can be output.

Next, the voltage command generation section 730 generates the voltage command value I ^{* based on} the current command value I ^* from the current command generation section 720 and the detected input current Is corresponding to the input AC power source Vs, (V ^* ) can be generated and output.

To this end, the voltage command generation unit 730 may include a computing unit 735, a current controller 737, and a computing unit 739.

The calculator 735 calculates the difference between the current command value I ^* and the input current Is detected by the input current detector D and transfers the difference to the current controller 737. [

The current controller 737 can generate the voltage command value through the PI control or the like based on the difference between the current command value I ^* and the input current Is detected by the input current detector D. [ On the other hand, the generated voltage command value may include a signal corresponding to the duty.

On the other hand, the forward compensation unit 740 may perform feed-forward compensation to remove the disturbance caused by the input voltage Vs and the dc voltage Vdc of the boost converter 420. [ Accordingly, the forward compensation section 740 can generate the compensation voltage command value corresponding to the second duty, taking into account the disturbance cancellation.

The computing unit 739 can add the voltage command value from the current controller 737 and the compensation voltage command value from the deflection compensation unit 740 and output the final voltage command value V ^* accordingly.

For example, the operator 739 adds the duty of the voltage command value from the current controller 737 and the second duty of the compensation voltage command value from the deflection compensation unit 740, and outputs the final voltage command value V ^* ) Can be output.

Next, the switching frequency variable section 770 can set the switching frequency Fsw of the switching element based on the level or phase of the input AC power supply Vs.

On the other hand, the switching frequency variable portion 770 can set the switching frequency Fsw of the switching element based on the output power based on the DC power or the DC power.

Specifically, the switching frequency varying section 770 calculates the switching frequency of the input voltage Vc based on the phase information? Of the input voltage detected by the input voltage detecting section A and the dc voltage detected by the dc voltage detecting section B The switching frequency Fsw of the switching element can be set based on the power P.

For example, the switching frequency variable section 770 divides the half period of the input AC power supply Vs into a plurality of sections based on the level or the phase information [theta] of the input AC power supply Vs, The switching frequency of the switching element can be varied for some sections.

As another example, the switching frequency variable portion 770 can vary the frequency of the switching element for a part of the half period of the input AC power supply Vs based on the load, that is, the calculated power P .

Various switching frequency variable operations, based on the phase information (?) Or the calculated power (P), of the switching frequency variable portion 770 can be performed as follows.

For example, the converter control section 215, in particular, the switching frequency variable section 770 divides a half cycle into a plurality of sections according to the level or phase of the input AC power supply Vs, , The switching frequency of the switching element can be varied.

The converter control unit 215, in particular, the switching frequency variable unit 770 divides the half period of the input power supply 201 into a plurality of sections so that the switching element S1 in the converter 210 has the first switching frequency And a third section having a second switching frequency lower than the first switching frequency and being driven between the first section and the second section having the first switching frequency and the second section having the second switching frequency.

On the other hand, the converter control unit 215, in particular, the switching frequency variable unit 770, can vary the second switching frequency in the third section according to the load 205 of the converter output stage. In particular, the converter control unit 215, in particular, the switching frequency variable unit 770, can control so that the second switching frequency becomes higher as the load 205 of the converter output stage becomes larger.

Meanwhile, the converter control unit 215, in particular, the switching frequency variable unit 770, can control the interval width between the first section and the second section to become smaller as the load 205 of the converter output stage becomes larger.

On the other hand, the converter control section 215, in particular, the switching frequency variable section 770, can control the section width of the third section to increase as the load 205 of the converter output stage becomes larger.

Meanwhile, the converter control unit 215, in particular, the switching frequency variable unit 770 controls the half period of the input power supply 201 to be the half period of the first period and the third period, the fourth period, The fifth section between the sections is further divided into the fifth section and the fourth section and the fifth section is controlled by the second switching frequency so that the switching elements in the converter operate.

Meanwhile, the converter control unit 215, in particular, the switching frequency variable unit 770 is further divided into a fourth section between the first section and the third section, and a fifth section between the third section and the second section And control the switching elements in the converter to operate by the third switching frequency higher than the second switching frequency and lower than the first switching frequency in the fourth and fifth sections.

Meanwhile, the converter control unit 215, in particular, the switching frequency variable unit 770 controls the half period of the input power supply 201 to be the half period of the first period and the third period, the fourth period, The fifth interval between the first and second sections is further divided so that the interval width between the first section and the second section becomes smaller as the load 205 of the converter output stage becomes larger or the interval width between the fourth section and the fifth section becomes wider can do.

Meanwhile, the converter control unit 215, in particular, the switching frequency variable unit 770 controls the half period of the input power supply 201 to be the half period of the first period and the third period, the fourth period, The fifth section between the sections is further divided into the fifth section and the third section through the fifth section as the load 205 of the converter output stage becomes larger.

Meanwhile, the converter control unit 215, in particular, the switching frequency variable unit 770, determines whether the switching frequency in the third period from the third period to the fifth period is greater than the switching frequency in the fourth period and the third period It is possible to control the switching frequency to be larger than the switching frequency in the fifth section.

Meanwhile, the converter control unit 215, in particular, the switching frequency variable unit 770 may change the second switching frequency according to the current level flowing through the inductor L1 in the converter 210, .

More specifically, the converter control unit 215, in particular, the switching frequency variable unit 770 can control the switching frequency to be lower as the current level flowing in the inductors L1 and L2 in the converter 210 is larger. In particular, the second switching frequency can be controlled to be lower than the first switching frequency.

Next, the switching control signal output section 760 can output the converter switching control signal Scc based on the voltage command value V ^* and the set switching frequency fsw.

6 to 10B are diagrams referred to in the description of the operation of the converter control unit of FIG.

6 is a diagram illustrating various examples of the switching mode of the converter.

6A illustrates a case where the converter operates in a critical conduction mode. FIG. 6B illustrates a case where the converter operates in a continuous conduction mode. Fig.

In the critical conduction mode of FIG. 6 (a) or the continuous conduction mode of FIG. 6 (b), when the switching element in the converter is driven for half a period of the input voltage, A switching loss is generated.

Particularly, in the high-speed switching, the switching loss due to the switching operation of the switching element becomes large.

On the other hand, when the switching element in the converter is operated in the discontinuous conduction mode in addition to the continuous conduction mode of FIG. 6B, the switching loss of the switching element is further reduced.

However, in the discontinuous conduction mode, the switching loss is reduced, but the conduction loss is increased as compared with the continuous conduction mode.

In the present invention, in order to solve this problem, it is assumed that a discontinuous conduction mode and a continuous conduction mode are used together.

Specifically, the converter control unit 215 operates the switching element in a discontinuous conduction mode in which the switching loss is smaller during the first and second periods, which are both ends of the half cycle of the input AC power source, It is preferable to control the switching element to operate in a continuous conduction mode in which the conduction loss is smaller during the third period between the first and second sections of the half cycle of the input AC power source.

In addition, in the discontinuous conduction mode, the converter control unit 215 does not increase the switching loss despite the increase of the switching frequency. Therefore, the converter control unit 215 controls the first and second sections, which are both ends of the half cycle of the input AC power, Is set to be higher than the switching frequency in the third section between the first and second sections of the half cycle of the input AC power source.

Figure 7 illustrates that the switching mode of the converter is a mixture of a Discon- tinuous Conduction Mode and a Continuous Conduction Mode according to an embodiment of the present invention.

Particularly, during the first period Pa and the second period Pc which are both ends of the half period of the input AC power supply, the switching element operates in a discontinuous conduction mode in which the switching loss is smaller, The switching device operates in a continuous conduction mode in which the conduction loss is smaller during the third section Pb of the half period of the AC power source during the first and second sections.

Accordingly, in the first and second sections, which are both ends of the half cycle of the input AC power supply Vs, in the discontinuous conduction mode, as compared with the continuous conduction mode, The turn-off loss and the turn-on loss of the switching element become smaller, so that the converter operation efficiency is increased.

On the other hand, the waveform 710 in the figure indicates the current flowing in the inductor L1 of Fig.

In the figure, the switching frequency during the first period (Pa) and the second period (Pc) which are both ends of the half period of the input AC power source is f2 and the switching frequency between the first and second periods And the switching frequency at the third section Pb of the first switch SW1 is f1 lower than f2.

Thus, by switching the switching frequency of the switching element for at least a part of a plurality of sections by dividing the half period of the input AC power into a plurality of sections, the switching loss and conduction loss of the converter switching element can be reduced, The converter efficiency can be increased.

The switching frequency of the switching element in the first period and the second period, which are both ends of the half period of the input AC power supply (Vs), is the half of the period of the input AC power supply (Vs) By setting the switching frequency higher than the switching frequency in the third section, the current ripple is reduced in the frequency variable section due to the increase of the switching frequency, and the conduction loss of the switching element and the core loss of the reactor or the inductor can be reduced. Thus, the converter efficiency can be increased.

On the other hand, as the load of the output terminal of the converter becomes larger and the load of the output terminal of the converter 210 becomes larger, the first and second section periods of operating in the discontinuous conduction mode are small .

8 is a diagram illustrating the magnitude of the current ripple according to the switching frequency within a half period of the input power supply.

Referring to the drawing, Thf denotes a half period of the input power supply 201, and each of f1, f2, and f3 is a current flowing in converter 210, in particular, inductor L1, according to a switching frequency of 30 kHz, 60 kHz, Current.

When the switching element in the converter 210 is driven with the switching frequency of 30 kHz, considerable current ripple occurs as shown in the drawing. However, when the switching element S1 is driven with the switching frequency of 60 kHz and 120 kHz, Is significantly reduced.

On the other hand, according to FIG. 8, it can be seen that the change in the current ripple is considerably large in the regions on both sides, although the change in the current ripple does not occur in the middle region due to the switching frequency variation.

The converter control section 215 divides the half period of the input power supply 201 into a plurality of sections so that the switching element S1 in the converter 210 is divided into a plurality of sections, The first and second sections having the first switching frequency, and the third section having the second switching frequency lower than the first switching frequency, between the first section and the second section.

Alternatively, the converter control unit 215 further divides the half period of the input power supply 201 into a fourth period, a fifth period between the third period and the second period, between the first period and the third period , And controls the switching elements in the converter to operate by the second switching frequency in the fourth section and the fifth section.

Figs. 9A to 10B illustrate the variable of the switching frequency or the length of the section according to the load.

First, FIG. 9A shows a configuration in which the half period of the input power source 201 is divided into a plurality of sections, and the first and second sections pa1 and pa2 having the first switching frequency fsa1, the first and second sections pa1 and pa2, Pa3 and Pa3 which are lower than the first switching frequency fsa1 and have a second switching frequency fsa2.

9A, the converter control unit 215 divides the half period of the input power supply 201 into a plurality of sections and generates first and second sections pa1 and pa2 having a first switching frequency fsa1, And a third section Pa3, Pa4, Pa5 having a second switching frequency fsa2 lower than the first switching frequency fsa1 between the second section pa1 and the second section pa2, have.

That is, as shown in FIG. 9A, when the switching element S1 in the converter 210 switches between the iLix waveform and the iLia waveform, the converter controller 215 controls the first and second sections pa1 and pa2 to the first switching frequency fsa1 and to switch the third intervals Pa3 to Pa to the second switching frequency fsa2.

Next, the converter control section 215 can vary the second switching frequency in the third section according to the load 205 at the converter output stage. In particular, as shown in FIG. 9B, the converter control section 215 can control the second switching frequency fsb2 to be higher as the load 205 of the converter output stage becomes larger.

That is, as shown in FIG. 9B (b), when the switching element S1 in the converter 210 switches between the iLix waveform and the iLib waveform, the converter controller 215 controls the first and second sections pb1 and pb2 to the first switching frequency fsb1 while switching the third switching frequency fsb2 from the third interval Pb3 to Pb4 to the second switching frequency fsb2.

Referring to FIG. 9B, it can be seen that the second switching frequency fsb2 of FIG. 9B is larger than the second switching frequency fsa2 of FIG. 9A.

In this manner, the switching efficiency in the third section is increased because the current ripple is relatively large, according to the load 205 at the converter output stage, so that the switching efficiency can be improved.

On the other hand, the converter control unit 215 can control the interval width between the first section pb1 and the second section pb5 to be smaller as the load 205 of the converter output stage becomes larger, as shown in Fig. 9B.

It can be seen that the widths of the sections of the first section pb1 and the section of the second section pb5 in Fig. 9B are smaller than the sections of the sections of the first section pa1 and the second section pa5 in Fig. 9A, respectively .

On the other hand, the converter control section 215 can control the section width of the third section Pb3, Pb4, and Pb5 to be larger as the load 205 of the converter output end becomes larger as shown in Fig. 9B.

It can be seen that the width of the section of the third section Pb3, Pb4, Pb5 in FIG. 9B is larger than the section width of the third section Pa3, Pa4, Pa5 of FIG. 9A.

On the other hand, the converter control unit 215 controls the half period of the input power supply 201 so that the fourth interval Pc2 between the first interval pc1 and the third interval Pc3 and the third interval Pc2 between the third interval Pc3, And a fifth section Pc4 between the second section Pc3 and the second section Pc5 in the fourth section pc2 and the fifth section pc4 in the fourth section pc2. It is possible to control the switching element s1 in the converter 210 to operate by the third switching frequency fsc3 lower than the switching frequency fsc1.

9C, the third switching frequency fsc3 in FIG. 9C) is larger than the second switching frequency fsc2.

As described above, since the switching frequency is increased in the fourth section pc2 and the fifth section pc4 in which the current ripple is relatively large, the switching efficiency can be improved.

9C, it can be seen that the second switching frequency fsc2 of FIG. 9C is larger than the second switching frequency fsb2 of FIG. 9B.

On the other hand, the converter control unit 215 can control the interval width between the first section pc1 and the second section pc5 to be smaller as the load 205 of the converter output stage becomes larger as shown in Fig. 9C.

It can be seen that the widths of the sections of the first section pc1 and the second section pc5 in Fig. 9C are smaller than the sections of the sections of the first section pb1 and the second section pb5 in Fig. 9B .

On the other hand, the converter control unit 215 converts the half period of the input power source 201 into a fourth period Pc2 between the first period pc1 and the third period Pc3, And the fifth section Pc4 between the fourth section Pc3 and the second section Pc5 and the interval between the fourth section Pc2 and the fifth section pc4 as the load 205 of the converter output stage becomes larger, The width can be controlled to be widened.

On the other hand, the converter control unit 215 converts the half period of the input power source 201 into a fourth period Pc2 between the first period pc1 and the third period Pc3, The fifth section Pc4 between the third section Pc3 and the second section Pc5 is further divided into the third section Pc3 and the third section Pc4 as the load 205 of the converter output stage becomes larger. It is possible to control the switching frequency to be increased.

That is, compared to FIG. 9B, by controlling the switching frequency in the third to fifth periods pc2, pc3, pc4 in FIG. 9C to be larger, the switching efficiency can be improved despite the increase in load.

On the other hand, as the load 205 of the converter output stage becomes larger, the converter controller 215 controls the switching frequency of the third section pc3 of the third section to the fifth section pc2, pc3, It is possible to control the switching frequency to be larger than the switching frequency in the fifth section.

The switching efficiency can be improved by increasing the switching frequency in the third section pc3 in which the current ripple is relatively small.

The converter control unit 215 may vary the second switching frequency or vary the widths of the first and second sections in accordance with the current level flowing through the inductors L1 and L2 in the converter 210. [

More specifically, the converter control section 215 can control so that the switching frequency becomes lower as the current level flowing in the inductor L1 in the converter 210 is larger. In particular, the second switching frequency can be controlled to be lower than the first switching frequency.

10A operates in a discontinuous conduction mode during the first period T1 and the second period T5 which are both ends of the half period of the input AC power supply Vs and the first period T1 (Continuous Conduction Mode) during the third interval T3, the fourth interval T2, and the fifth interval T4, which are the first interval T3 and the second interval T5.

On the other hand, unlike the drawing, a fourth section P2 between the first section P1 and the third section P3 and a fifth section P5 between the third section P3 and the second section P2 , And the continuous conduction mode (continuous conduction mode).

On the other hand, in Fig. 10A, the switching element S1 in the converter 210 can be controlled to switch between the iLiy waveform and the iLiz waveform when switching.

On the other hand, FIG. 10B shows that the half period of the input power source 201 is controlled to operate at the first switching frequency fsd1 in the first interval T1 and the second interval T5, And the third period T3 between the first period T3 and the second period T5 so as to operate at a second switching frequency fsd2 lower than the first switching frequency fsd1, Is higher than the second switching frequency fsc2 and between the third period T3 and the second period T5 between the third period T3 and the fourth period T2 between the third period T3 and the second period T5, And controls the switching element s1 in the converter 210 to operate with the third switching frequency fsc3 lower than the frequency fsc1.

The converter controller 415 changes the switching frequency in the first period T1 and the second period T5 so that the conduction loss and the switching loss are traded off, The maximum frequency can be selected as the optimum frequency.

The converter control section 415 selects the minimum frequency for satisfying the input current harmonic criterion because the current ripple flowing through the inductor L1 is the largest in the fourth section T2 and the fifth section T4 desirable.

The converter control section 415 has a large current ripple flowing in the inductor L1 in the third section T3 and is a section having the smallest ripple increase amount due to frequency reduction as shown in Fig. . However, a higher frequency may be selected than the fourth section T2 and the fifth section T4.

Conversely, converter 210 described above may include a buck converter, a boost converter, a buck boost converter, an interleaved buck converter, an interleaved boost converter, or an interleaved buck boost converter. The above-described switching frequency variable and the like can be applied as they are.

11 is another example of a circuit diagram of the power conversion apparatus of Fig.

Referring to the drawings, the power conversion apparatus of FIG. 11 may include interleave converters 420a and 420b. In particular, boost interleave converters 420a and 420b may be provided.

That is, it is exemplified that the converter 210 includes the rectifier 410a and the boost interleaved converters 420a and 420b.

The rectifying unit 410a receives the single-phase AC power source 201 and rectifies it to output rectified power.

To this end, the rectifying part 410a includes pairs of the upper and lower laminated diode elements Da and Db and the downam diode elements D'a and D'b connected in series to each other, and two pairs of upper and lower arm diode elements Are connected to each other in parallel (Da & D & a, Db & D'b). That is, they can be connected to each other in the form of a bridge.

The first boost converter 420a and the second boost converter 420b are connected in parallel to each other and are disposed between the rectifier 410a and the capacitor C. [

The first boost converter 420a includes a first diode D1 whose one end is connected to the capacitor C, a first inductor L1 connected between the first diode D1 and the rectifying unit 410, And a first boost switching element S1 connected in parallel to the first diode D1 and the first diode D1.

The second boost converter 420b includes a second diode D2 whose one end is connected to the capacitor C, a second inductor L2 connected between the second diode D2 and the rectifier 410, And a second boost switching element S2 connected in parallel to the second inductor L2 and the second diode D2.

The first current detector F1 detects the current i _L1 flowing through the first inductor L1 in the first boost converter 420a and the second current detector F2 detects the current i _L1 flowing through the second inductor L1 in the second boost converter 420b. It is possible to detect the current (i _L2 ) flowing through the second inductor (L2). For this purpose, a CT (current trnasformer), a shunt resistor, or the like may be used as the first and second current detectors F1 and F2. The inductor current (i _L1 , i _L2 ) to be detected can be input to the converter control unit 415 as a discrete signal in the form of a pulse.

On the other hand, the converter control unit 415 generates a first converter switching control signal for controlling the first boost converter 420a based on the detected current i _L1 , the dc step voltage Vdc, the input voltage Vs, And generates and outputs a second converter switching control signal Scc1 for controlling the second boost converter 420b based on the detected current i _L2 , the dc step voltage Vdc, the input voltage Vs, (Scc2) can be generated and output.

12 is an example of an internal block diagram of the inverter control unit of FIG.

12, the inverter control unit 230 includes an axis conversion unit 310, a speed calculation unit 320, a current command generation unit 330, a voltage command generation unit 340, an axis conversion unit 350, And a switching control signal output unit 360.

The axial conversion unit 310 receives the three-phase output currents ia, ib, ic detected by the output current detection unit E and converts the three-phase output currents ia, ib, ic into the two-phase currents iα, iβ in the stationary coordinate system.

On the other hand, the axis converting unit 310 can convert the two-phase current i ?, i? Of the still coordinate system into the two-phase current id, iq of the rotating coordinate system.

)와 연산된 속도(

)를 출력할 수 있다.Based on the two-phase current (i?, I?) Of the stationary coordinate system changed in the axis by the axis converting unit 310, the speed calculating unit 320 calculates the speed

) And the calculated speed (

Can be output.

)와 속도 지령치(ω^* _r)에 기초하여, 전류 지령치(i^* _q)를 생성한다. 예를 들어, 전류 지령 생성부(330)는, 연산 속도(

)와 속도 지령치(ω^* _r)의 차이에 기초하여, PI 제어기(335)에서 PI 제어를 수행하며, 전류 지령치(i^* _q)를 생성할 수 있다. 도면에서는, 전류 지령치로, q축 전류 지령치(i^* _q)를 예시하나, 도면과 달리, d축 전류 지령치(i^* _d)를 함께 생성하는 것도 가능하다. 한편, d축 전류 지령치(i^* _d)의 값은 0으로 설정될 수도 있다. On the other hand, the current command generation unit 330 generates the current command

(I ^* _q ) on the basis of the speed command value? ^* _R and the speed command value? ^* _R. For example, the current command generation section 330 generates the current command

The PI controller 335 performs the PI control based on the difference between the speed command value? ^* _R and the speed command value? ^* _R , and generates the current command value i ^* _q . In the figure, the q-axis current command value (i ^* _q ) is exemplified by the current command value, but it is also possible to generate the d-axis current command value (i ^* _d ) unlike the figure. On the other hand, the value of the d-axis current command value i ^* _d may be set to zero.

On the other hand, the current command generation section 330 may further include a limiter (not shown) for limiting the current command value (i ^* _q ) so that the current command value (i ^* _q ) does not exceed the allowable range.

Next, the voltage command generating unit 340 generates the voltage command generating unit 340 with the d-axis and q-axis currents (i _d , i _q ) axially transformed into the two-phase rotational coordinate system in the axial converting unit and the current command value based on ^{_{i * d, i * q)}} , and generates a d-axis, q-axis voltage command value ^{_{(v * d, v * q}} ). For example, the voltage command generation unit 340 performs PI control in the PI controller 344 based on the difference between the q-axis current (i _q ) and the q-axis current command value (i ^* _q ) It is possible to generate the axial voltage command value v ^* _q . The voltage command generation unit 340 performs PI control in the PI controller 348 based on the difference between the d-axis current i _d and the d-axis current command value i ^* _d , It is possible to generate the command value v ^* _d . The voltage command generator 340 may further include a limiter (not shown) for limiting the level of the d-axis and q-axis voltage command values v ^* _d and v ^* _q so as not to exceed the permissible range .

On the other hand, the generated d-axis and q-axis voltage command values (v ^* _d and v ^* _q ) are input to the axial conversion unit 350.

)와, d축, q축 전압 지령치(v^* _d,v^* _q)를 입력받아, 축변환을 수행한다.The axis transforming unit 350 transforms the position calculated by the velocity calculating unit 320

) And the d-axis and q-axis voltage command values (v ^* _d , v ^* _q ).

)가 사용될 수 있다.First, the axis converting unit 350 performs conversion from a two-phase rotating coordinate system to a two-phase stationary coordinate system. At this time, the position calculated by the speed calculator 320 (

) Can be used.

Then, the axial conversion unit 350 performs conversion from the two-phase stationary coordinate system to the three-phase stationary coordinate system. Through this conversion, the axial conversion unit 1050 outputs the three-phase output voltage instruction values v ^* a, v ^* b, v ^* c.

The switching control signal output section 360 generates the switching control signal Sic for inverter according to the pulse width modulation (PWM) method based on the three-phase output voltage instruction values v ^* a, v ^* b and v ^* And outputs it.

The output inverter switching control signal Sic may be converted into a gate driving signal at the gate driver (820a, 820b, etc. in FIG. 8A or 8B) and input to the gate of each switching element in the inverter 420. As a result, the switching elements Sa, S'a, Sb, S'b, Sc, and S'c in the inverter 420 perform the switching operation.

The power conversion apparatus and the air conditioner having the power conversion apparatus according to the present invention are not limited to the configuration and method of the embodiments described above, Or some of them may be selectively combined.

Meanwhile, the operation method of the power conversion apparatus or the air conditioner of the present invention can be implemented as a code that can be read by a processor on a processor-readable recording medium provided in a power conversion apparatus or an air conditioner. The processor-readable recording medium includes all kinds of recording apparatuses in which data that can be read by the processor is stored. Examples of the recording medium that can be read by the processor include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and may also be implemented in the form of a carrier wave such as transmission over the Internet . In addition, the processor-readable recording medium may be distributed over network-connected computer systems so that code readable by the processor in a distributed fashion can be stored and executed.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention.

Claims (19)

A converter having a switching element and converting an input AC power into a DC power and outputting the DC power;
And a control unit for controlling the converter,
Wherein,
A first and a second section having a first switching frequency and a second section having a second switching frequency lower than the first switching frequency, And controls the switching device in the converter so as to be divided into a third section and a third section. The method according to claim 1,
Wherein,
Depending on the load of the converter output stage,
And changes the second switching frequency in the third section. 3. The method of claim 2,
Wherein,
And controls the second switching frequency to be higher as the load of the converter output terminal increases. The method according to claim 1,
Wherein,
The greater the load on the converter output stage,
And controls the interval between the first section and the second section to be small. The method according to claim 1,
Wherein,
The greater the load on the converter output stage,
So that the section width of the third section is increased. The method according to claim 1,
Wherein,
Wherein the half period of the input power source
A fourth section between the first section and the third section, and a fifth section between the third section and the second section,
And controls the switching element in the converter to operate by the second switching frequency in the fourth section and the fifth section. The method according to claim 1,
Wherein,
Wherein the half period of the input power source
A fourth section between the first section and the third section, and a fifth section between the third section and the second section,
And controls the switching element in the converter to operate by a third switching frequency higher than the second switching frequency and lower than the first switching frequency in the fourth section and the fifth section. . The method according to claim 1,
Wherein,
Wherein the half period of the input power source
A fourth section between the first section and the third section, and a fifth section between the third section and the second section,
The greater the load on the converter output stage,
The interval width between the first section and the second section becomes small,
And controls the interval between the fourth section and the fifth section to be widened. The method according to claim 1,
Wherein,
Wherein the half period of the input power source
A fourth section between the first section and the third section, and a fifth section between the third section and the second section,
The greater the load on the converter output stage,
And controls the switching frequency in the third period to the fifth period to be large. 10. The method of claim 9,
Wherein,
And controls the switching frequency in the third section to be greater than the switching frequency in the fourth section and the fifth section as the load of the converter output terminal increases. Conversion device. The method according to claim 1,
The converter includes:
An inductor, a diode, and a switching element connected between the inductor and the diode,
Wherein,
Wherein the second switching frequency is varied according to a current level flowing through the inductor or the width of the first section and the second section is varied. The method according to claim 1,
Wherein,
A current command generator for generating a current command value based on the DC power source; And
A voltage command generator for generating a voltage command value based on the current command value and an input current corresponding to the input AC power source; And
A switching frequency varying unit for setting a switching frequency of the switching device based on a phase of the input AC power source;
And a switching control signal output unit for outputting the converter switching control signal based on the voltage command value and the set switching frequency. 13. The method of claim 12,
The switching frequency-
And sets a switching frequency of the switching element based on the DC power source or the output power based on the DC power source. 13. The method of claim 12,
Wherein the current command generator comprises:
And generates the current command value by synchronizing the phase and the shape of the input voltage. 13. The method of claim 12,
Wherein,
Further comprising: a deflection compensating unit for compensating a disturbance of the input AC power source,
Wherein the switching control signal output unit comprises:
And outputs the converter switching control signal based on the compensation voltage instruction value from the deflection compensation unit, the voltage instruction value, and the set switching frequency. The method according to claim 1,
The converter includes:
A rectifying unit for rectifying the input AC power;
And an inductor connected between the rectifying part and the switching element,
Wherein,
Wherein a frequency of a current flowing in the inductor in first and second sections that are both ends of a half period of the input AC power supply is greater than a frequency of a current flowing in the third section between the first and second sections Is set to be higher than the frequency of the current flowing in the inductor. The method according to claim 1,
A buck converter, a boost converter, a buck-boost converter, or an interleaved converter. The method according to claim 1,
A capacitor for storing DC power from the converter;
And an inverter for converting the DC power stored in the capacitor into an AC power and outputting the AC power to the motor. An air conditioner comprising the power conversion device according to any one of claims 1 to 18.

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