KR20110077801A - Apparatus and method for supplying dc power source - Google Patents

Abstract

PURPOSE: A device and method for supplying DC power are provided to reduce manufacturing costs and efficiently control a DC power supply device by reducing the number of switching elements and inductors comprising a converter. CONSTITUTION: A power magnitude determining unit(305) compares a reference magnitude with a line voltage of two phase input power among three phase input power. The power magnitude determining unit determines the input power state according to the comparison result. A converting unit(320) converts an AC voltage into a DC voltage according to a first control signal. The converting unit includes a smoothing capacitor(315) and a rectifier composed of two single phase active filters(310,360). An inverting unit(330) converts the DC voltage into the AC voltage according to a second control signal.

Description

DC power supply and DC power supply method {APPARATUS AND METHOD FOR SUPPLYING DC POWER SOURCE}

The present invention relates to a direct current power supply and a method thereof, and more particularly to a direct current power supply and a method for controlling a two-phase voltage selected from a three-phase input power supply.

In addition, the present invention is to reduce the number of switching elements and inductors constituting the converting unit in the DC power supply, DC power supply device and method that can easily control the DC power supply and reduce the manufacturing cost It is about.

Conventional DC power supply for driving a compressor motor of an air conditioner or refrigerator including a PFC circuit composed of three inductors, six switch elements, and six diodes is known to be relatively stable in operation and implementation. In demanding applications such as air conditioners, which are highly competitive and inexpensive, the demand for low cost is increasing due to the expensive semiconductor devices and reactors required to implement PFC circuits.

An object of the present invention is to provide a DC power supply and a method for controlling a two-phase voltage selected from a three-phase input power source.

In addition, the present invention by reducing the number of switching elements and the inductor constituting the converting unit in the DC power supply device, a DC power supply device and a method that can facilitate the control of the DC power supply and reduce the manufacturing cost To provide.

In order to achieve the above object, the DC power supply apparatus according to the present invention, in the DC power supply for controlling a two-phase voltage selected from the three-phase input power source, the line voltage of the two-phase input power of the three-phase input power source A power size judging unit for detecting and comparing with a reference size and determining a state of input power according to the comparison result; A converting unit having two single-phase active filters and a smoothing capacitor, converting an AC voltage into a DC voltage according to the first control signal; And an inverting unit converting the converted DC voltage into an AC voltage according to a second control signal, wherein the single phase active filter is a bridge diode that converts a single phase AC voltage supplied from an AC power source into a DC voltage. Configured rectifier; An inductor connected to the first terminal of the rectifier; A switch connected between the inductor and the second terminal of the rectifier; And a diode connected between the first terminal of the switch and the first terminal of the capacitor.

The DC power supply may further include a shunt resistor connected between the second terminal of the rectifier and the second terminal of the switch.

The DC power supply may detect the current of the inductor using the shunt resistor.

The DC power supply device may further include a phase shifting means to generate a half cycle phase difference in the gate voltage between the switches included in the two single-phase active filters.

The DC power supply may further include a freewheeling diode in which the switch is connected in parallel to the switch.

The DC power supply device may block a path of current when switching through the freewheeling diode.

The DC power supply device may store the DC voltage converted through the rectifier through the inductor.

In order to achieve the above object, the DC power supply method according to the present invention, in the DC power supply method for controlling the two-phase voltage selected from the three-phase input power source, using a power size determination unit of the two-phase three-phase input power source A power state judging step of detecting a line voltage of an input power source and comparing the input voltage with a reference magnitude, and determining a state of the input power source according to the comparison result; A DC voltage conversion step of converting an AC voltage into a DC voltage according to a first control signal by using a converting unit including two single-phase active filters and a smoothing capacitor; And an AC voltage conversion step of converting the converted DC voltage into an AC voltage according to a second control signal using an inverting unit, wherein the DC voltage conversion step includes: a bridge diode included in the single phase active filter. Extracting a DC voltage by rectifying the single-phase AC voltage supplied from the AC power supply using the AC power supply; And storing the extracted DC voltage using an inductor.

The DC power supply method may detect a current of the inductor using a shunt resistor included in the single phase active filter.

In the DC power supply method, a phase difference of a half period may be generated in a gate voltage between switches included in the two single-phase active filters by using a phase shifting means.

The DC power supply method may block a path of current during switching by using a freewheeling diode connected in parallel to the switch.

The DC power supply method may supply power to a motor coupled to the inverting unit by using the stored DC voltage.

The DC power supply method may be a compressor driving motor in which the motor is included in at least one of an air conditioner, a washing machine, and a refrigerator.

The present invention provides the following effects and advantages.

First, the DC power can be supplied by efficiently controlling the two-phase voltage selected from the three-phase input power.

Second, by reducing the number of switching elements constituting the converter in the DC power supply and the number of inductors, it is easy to control the DC power supply and reduce the manufacturing cost.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in this specification and claims should not be interpreted in a conventional or dictionary sense, and the inventors will appropriately define the concept of terms in order to best describe their invention. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that it can. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

1 illustrates a DC power supply including a conventional three-phase PFC converter. As shown in FIG. 1, a DC power supply device 100 including a conventional three-phase PFC converter is composed of three inductors, and includes a reactor 110 for reducing harmonics of an input current, according to a first control signal. A converter 120 for converting the voltage into a DC voltage; And an inverter 130 for converting the converted DC voltage into an AC voltage according to a second control signal.

The reactor 110 may vary the reactance value of the reactor 110 to adjust the resonance frequency according to the power variation of the three-phase input power, but may be fixed by the user in advance according to the required power of the load. It may be determined as an element having a value.

The converter 120 includes a rectifying unit 140 and a smoothing capacitor 150 including six switches and six body diodes connected in parallel with each switch. Six switches are typically IGBTs with a switching frequency of 5 to 20 kHz. Therefore, connected body diodes in parallel with six switches are expensive diodes that have good reverse recovery characteristics in order to reduce switching losses even in fast switching.

The inverter 130 may drive the motor 160 by converting the smoothed DC voltage into the AC voltage through the rectifying unit 140 and the smoothing capacitor 150 according to the second control signal.

Meanwhile, the smoothing capacitor 150 included in the converter 120 smoothes the voltage output through the rectifier 140 to be a DC voltage, and supplies the smoothed DC voltage to the inverter 130 and the rectifier ( The switch included in 140 serves to adjust the current path of the rectified input power.

The motor 160 coupled to FIG. 1 may be used in combination with an air conditioner, a washing machine, or the like, but the present invention is not limited thereto.

In order to satisfy the harmonic standard EN61000-3-2, the input current should be similar to a sine wave, and a three-phase PFC converter as shown in FIG. 1 may be used for this purpose. In the three-phase PFC converter, when the three-phase voltage source is input and full-wave rectified, the DC-link voltage, which means the voltage between A and B of FIG. To make sine wave of each phase voltage and phase.

The control method of the DC power supply 100 generally uses sine curve pulse width modulation (sinusoidal PWM) control or vector control. The switching method for driving each switch uses a method of fixing a carrier frequency and varying a duty cycle.

2 is a block diagram of a DC power supply including a conventional three-phase PFC converter.

As shown in FIG. 2, the conventional DC power supply device 200 includes a three-phase AC power supply 210, a reacting unit 220, a converting unit 230, and an inverting unit 240. Butting unit 240 is connected to the motor 250, the converting unit 230 may be composed of a rectifying unit 260 and a smoothing unit (270).

On the other hand, the DC power supply 200 is the three-phase AC power source 210 and the reacting unit 220 to prevent noise contained in the three-phase AC power source 210 damages the components inside the power supply. EMI filter (270) may be further included between the power supply determining unit 280 for determining the state of the input power supply 210 and the converting unit 230 and based on the determination result. The control unit 290 for controlling the switching of the inverting unit 240 may be further included.

The above-described conventional DC power supply 200 includes a reacting unit 220 including three inductors, a rectifying unit 260 composed of six switches and six diodes, and the operation and implementation thereof are relatively Although it has a well-known and stable advantage, it is disadvantageous in that the cost burden is increased due to the expensive semiconductor devices and reactors required to implement a three-phase PFC converter in an application that requires a high price competition such as an air conditioner.

3 shows a DC power supply according to the present invention.

As shown in FIG. 3, the DC power supply 300 according to the present invention includes a power supply size determining unit 305, a rectifying unit composed of two single-phase active filters 310 and 360, and a smoothing capacitor 315. The converting unit 320 and the inverting unit 330 are included.

The power size determining unit 310 compares the line voltage of the two-phase input power of the three-phase input power with a reference size, determines the state of the input power according to the comparison result, and the converting unit 320 is the 2 The single voltage active filters 310 and 360 and the smoothing capacitor 315 are used to convert an AC voltage into a DC voltage according to a first control signal generated by a controller (not shown), and the inverting unit 330 is The DC voltage is converted into an AC voltage according to the second control signal generated by the controller, and the motor 335 connected to the inverting unit 330 is driven using the converted AC voltage.

Meanwhile, the single phase active filter 310 includes a rectifier 325, an inductor 340, a switch 345, and a diode 350. The rectifier 325 rectifies the AC voltage supplied from the AC power through the input current applied to the rectifier 325 using the bridge diode and stores the rectified voltage in the inductor 340.

The inductor 340 is connected to the first terminal of the rectifier 325, the switch 345 is connected between the inductor 340 and the second terminal of the rectifier 325, the diode 350 is the switch ( A first terminal of 345 and a first terminal of the capacitor 330.

Also, as shown in FIG. 2, the single phase active filter 310 additionally includes a shunt resistor 355 connected between the second terminal of the rectifying unit 325 and the second terminal of the switch 345. It can be used to detect the current of the inductor 340 by including.

The two single-phase active filters 310 and 360 included in the DC power supply 300 are configured in the same manner, and the single-phase active filter 310 controls the R phase of the three-phase input power and the single-phase active filter 360 ) Controls the T phase current, and the single phase active filters 310 and 360 may be controlled in the same manner as the single phase PFC converter. That is, in the single phase active filter 310, two diodes of the rectifier 370 are conducted during the half cycle of the AC input supplied from the AC power source. At this time, when the switch 345 included in the single-phase active filter 310 is turned on, an input voltage is applied to the inductor 340 so that the current flowing in the inductor 340 increases linearly and the inductor 340 Energy is stored. At this time, the diode 350 receives the reverse voltage from the smoothing capacitor 315 and is turned off.

After that, when the switch 345 is turned off, the diode 350 is turned on so that a reverse voltage is applied to the inductor 340 so that the current flowing in the inductor 340 decreases linearly. The energy that was stored at 340 is stored in capacitor 315.

Through the above process, it is possible to convert the three-phase AC power to DC power.

As described above, two phases of the R and T phases of the three-phase input power source are controlled, and the other one phase (S phase) has a sinusoidal shape since the sum of the three phase currents is zero. Meanwhile, since the high frequency ripple of the phase current of the S phase is represented by the sum of the ripples of the R phase and the S phase, a technique of reducing the ripple of the S phase by changing the phase of the gate waveforms of the two switches by half a cycle may be additionally required.

To this end, the DC power supply 300 according to the present invention further comprises a phase shifting means (not shown), so that the phase difference of the half period to the gate voltage between the switches included in the two single-phase active filters 310 and 360 It is possible to reduce the current ripple of the S phase which is not controlled by generating.

DC power supply 300 according to the present invention can reduce the production cost by reducing the number of switches from six to two and the number of inductors from three to two compared to the conventional DC power supply 100 Has the advantage. Meanwhile, the DC power supply 300 according to the present invention requires two additional bridge diodes, but the bridge diode may use a low cost diode as a very slow switching speed diode. Therefore, the increase in cost due to the bridge diode is not significant, and the increase in cost due to the switch is also not significant because the increase in the current rating of the switch is not required even though the number of switches is reduced.

4 is a block diagram of a DC power supply including a three-phase PFC converter according to the present invention.

As shown in FIG. 4, the DC power supply device 400 according to the present invention includes a three-phase AC power supply 410, a power size determining unit 420, a converting unit 430, and an inverting unit 440. The converting unit 430 includes a rectifying unit 450 and a smoothing unit 460, and the inverting unit 440 is connected to the motor 470. Meanwhile, the DC power supply device 400 determines the state of the input power 410 and controls the switching of the converting unit 430 and the inverting unit 440 based on the determination result. It may further include.

5 is a flowchart showing a DC power supply method according to an embodiment of the present invention. As shown in FIG. 5, in the DC direct current supply method according to the present invention, a power state determination step of detecting an input power using a power size determination unit, comparing the input power with a reference size, and determining a state of the input power according to the comparison result (S510), outputting the first and second control signals based on the determined state of the input power (S520), using a converter having two single-phase active filters and a smoothing capacitor, according to the first control signal DC voltage conversion step of converting the voltage to DC voltage (S530); And an AC voltage conversion step (S560) of converting the converted DC voltage into an AC voltage according to a second control signal using an inverter, wherein the DC voltage conversion step (S530) is included in the single phase active filter. Extracting the DC voltage by rectifying the single-phase AC voltage supplied from the AC power using the bridge diode (S540); And storing the extracted DC voltage using an inductor (S550).

The method may further include detecting a current of the inductor using a shunt resistor included in the single phase active filter (not shown).

6 schematically shows an embodiment of a DC power supply according to the present invention.

As illustrated in FIG. 6, the DC power supply 600 may be used in combination with a motor 610, and the motor 610 may be a compressor for driving a compressor included in an air conditioner, a washing machine, and a refrigerator. It may be a driving motor.

As mentioned above, preferred embodiments of the present invention are disclosed for purposes of illustration, and those skilled in the art can improve and change various other embodiments within the spirit and technical scope of the present invention disclosed in the appended claims below. , Replacement or addition would be possible.

1 illustrates a DC power supply including a conventional three-phase PFC converter.

2 is a block diagram of a DC power supply including a conventional three-phase PFC converter.

3 shows a DC power supply according to the present invention.

4 is a block diagram of a DC power supply including a three-phase PFC converter according to the present invention.

5 is a flowchart showing a DC power supply method according to an embodiment of the present invention.

6 schematically shows an embodiment of a DC power supply according to the present invention.

Claims (13)

In the DC power supply for controlling the two-phase voltage selected from the three-phase input power, A power size determination unit which detects a line voltage of the two-phase input power among the three-phase input power, compares the line voltage with a reference magnitude, and determines a state of the input power according to the comparison result; A converting unit having two single-phase active filters and a smoothing capacitor, converting an AC voltage into a DC voltage according to the first control signal; And, And an inverting unit converting the converted DC voltage into an AC voltage according to a second control signal. The single phase active filter may include: a rectifier configured of a bridge diode converting a single phase AC voltage supplied from an AC power source into a DC voltage; An inductor connected to the first terminal of the rectifier; A switch connected between the inductor and the second terminal of the rectifier; And a diode connected between the first terminal of the switch and the first terminal of the capacitor. The method of claim 1, And a shunt resistor connected between the second terminal of the rectifier and the second terminal of the switch. The method of claim 2, The shunt resistor is a DC power supply, characterized in that for detecting the current of the inductor. The method of claim 1, And a phase shifting means for generating a phase difference of a half period in the gate voltage between the switches included in said two single-phase active filters. The method of claim 1, The switch further comprises a freewheeling diode connected in parallel to the switch. The method of claim 5, The freewheeling diode is a DC power supply, characterized in that for blocking the path of current during switching. The method of claim 1, The inductor is a DC power supply, characterized in that for storing the DC voltage converted through the rectifier. In the DC power supply method for controlling the two-phase voltage selected from the three-phase input power, A power state judging step of detecting a line voltage of a two-phase input power among three-phase input power using a power size determination unit, comparing the line voltage with a reference size, and determining the state of the input power according to the comparison result; A DC voltage conversion step of converting an AC voltage into a DC voltage according to a first control signal by using a converting unit including two single-phase active filters and a smoothing capacitor; And, An AC voltage conversion step of converting the converted DC voltage into an AC voltage according to a second control signal using an inverting unit; The DC voltage conversion step may include extracting a DC voltage by rectifying a single phase AC voltage supplied from an AC power source using a bridge diode included in the single phase active filter; And, And storing the extracted direct current voltage using an inductor. The method of claim 8, And detecting a current of the inductor by using a shunt resistor included in the single phase active filter. The method of claim 8, And generating a half period phase difference in a gate voltage between the switches included in the two single-phase active filters by using a phase shifting means. 11. The method of claim 10, And using a freewheeling diode connected in parallel to the switch, blocking a path of current during switching. The method of claim 8, And supplying power to the motor coupled to the inverting unit by using the stored DC voltage. 13. The method of claim 12, The motor is a DC power supply method characterized in that the compressor driving motor included in at least one of an air conditioner, a washing machine, a refrigerator.

Images