JP2006074945A - Power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power converter capable of feeding a separate stable DC voltage while using a conventional power supply configuration by further smoothing a significantly pulsating voltage. <P>SOLUTION: This power converter includes a rectifying means 2 of full-wave-rectifying AC power; a first smoothing means 3 where such a value that an output voltage from the rectifying means 2 may be pulsated with a frequency twice as large as an AC power frequency is set; a load 11 power-supplied from the output of the first smoothing means 3; a control means 5 for controlling the load 11; and a second smoothing means 7 for smoothing an output voltage of the first smoothing means 3, thus obtaining a stable DC voltage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a configuration of an inverter device for connecting a smoothing means including a small-capacitance capacitor to an output terminal of a rectifying means and obtaining a DC voltage when the output voltage is pulsating.

  Conventionally, a stable DC voltage without pulsation cannot be obtained with a power converter having a smoothing means composed of this type of small-capacitance capacitor (see, for example, Patent Document 1).

FIG. 6 is an abbreviated view of the entire configuration of the conventional power conversion device described in Patent Document 1. In the power conversion device having such a configuration, since the output voltage from the smoothing means 3 is generally used to obtain a DC voltage, a DC voltage that pulsates greatly is obtained. For this reason, in the power converter having the smoothing means 3 composed of a small-capacitance capacitor, the load is controlled by the control means 5 in accordance with the pulsating output voltage.
JP 2002-223599 A

  However, in the conventional configuration, a separate DC power supply is provided to supply a stable DC voltage to the control means 5 constituted by a constant voltage driven microcomputer or the like or a load that needs to supply a stable DC voltage. There was a problem that it was necessary.

  An object of the present invention is to solve the above-described conventional problems, and to provide a power converter that can supply a stable DC voltage while using a conventional power supply configuration by further smoothing a large pulsating voltage. To do.

  In order to solve the above-mentioned conventional problems, the power conversion device of the present invention includes a rectifying unit for full-wave rectification of an AC power supply, and a value such that the output voltage from the rectifying means pulsates at twice the frequency of the AC power supply frequency. A second smoothing means for smoothing the output voltage of the first smoothing means, comprising: a set first smoothing means; a load supplied with power from the output of the first smoothing means; and a control means for controlling the load. In this way, a conventional power supply configuration can be used. For example, the capacity of the capacitor and the reactor constituting the smoothing means for operating a load such as a motor can be reduced. This makes it possible to reduce the size and cost, and to supply a stable DC constant voltage to a new load without using a separate DC power source.

  The power conversion device of the present invention can provide a power conversion device that can supply a separately stable DC voltage while further using a conventional power supply configuration by further smoothing a voltage that greatly pulsates.

  A power conversion device according to a first aspect of the present invention is a rectifier that full-wave rectifies an AC power supply, and a first smoothing means that sets a value so that an output voltage from the rectifier pulsates at twice the AC power supply frequency. A load supplied with electric power from the output of the first smoothing means; and a control means for controlling the load; and a second smoothing means for smoothing the output voltage of the first smoothing means. It is characterized in that a stable DC voltage can be supplied without using a separate power source from the smoothing means constituted by a conventional small-capacitance capacitor and reactor.

  A second invention is characterized in that, in the power converter of the first invention, the second smoothing means comprises at least an inductance, a capacitor, and a second rectifying means. The peak value of the inrush charging / discharging current to the capacitor constituting the means can be reduced by setting the inductance value, which can cope with power factor improvement and power supply harmonic regulation.

  A third invention is characterized in that, in the power converter of the second invention, the second rectifying means is constituted by a diode, and the second smoothing means can be constituted at low cost.

  According to a fourth invention, in the power conversion device according to any one of the first to third inventions, the output from the second smoothing means is supplied to the control means, and the control means is stabilized without using a separate power source. Can be operated.

  According to a fifth invention, in the power conversion device according to any one of the first to fourth inventions, the first smoothing means is constituted by a capacitor and a reactor, and the resonance frequency embodied by the capacitor and the reactor is defined as an AC power supply frequency. It is characterized in that it is set to be 40 times or more, and it is possible to realize high performance of the power supply harmonic characteristics of the input current to the rectifying means.

  A sixth invention is characterized in that, in the power conversion device according to any one of the first to fifth inventions, a film capacitor is used as a capacitor constituting the first smoothing means. The usage environment can be selected without worrying about the effects on the environment.

  In a seventh aspect of the invention, an air conditioner includes the power conversion device according to any one of the first to sixth aspects of the invention, and the size and cost of the device are reduced by reducing the capacity of the condenser and the reactor of the smoothing means. The control means and DC that consist of a microcomputer that requires constant voltage supply without adding a separate DC power supply and sufficiently reducing the peak value of the inrush charging / discharging current to the smoothing capacitor. A stable DC constant voltage can be supplied to a fan motor or the like.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a configuration diagram of an air conditioner 12 equipped with a power conversion device according to an embodiment of the present invention.

  1, the power converter mounted on the air conditioner 12 is configured by a diode bridge that is supplied with power from an AC power source 1 such as a commercial power source that is a single-phase AC power source and rectifies the supplied AC power source 1 in full-wave. Rectifying means 2, the smoothing means 3 in which the value of the capacitor 31 is set so that the output voltage from the rectifying means 2 pulsates greatly at twice the frequency of the AC power supply frequency, and the output voltage from the smoothing means 3 is converted into a motor. Orthogonal transformation means 4 composed of a plurality of semiconductor switching elements that convert it to a desired AC voltage for driving, and an orthogonal transformation means for driving a motor 6 of the compressor in response to a smooth pulsating smooth voltage 4 and a drive control means 5 constituted by a microcomputer, and a capacitor 7 through a reactor 72 and a diode 73 from a pulsating output voltage from the smoothing means 3. And a second smoothing means 7 for supplying a DC constant voltage smoothed and stabilized to the drive control means 5 and a second smoothing means 7 for supplying to the orthogonal transform means 9 for driving the DC fan motor 11. ing.

The smoothing means 3 includes a small-capacity film capacitor 31 set so that the resonance frequency is 40 times or more of the AC power supply frequency, and a reactor 32 for lowering the peak value of the inrush charging / discharging current to the film capacitor 31. have.

  Since the reactor 32 constituting the smoothing means 3 is inserted between the AC power source 1 and the film capacitor 31 constituting the smoothing means 3, it may be either before or after the rectifying means 2.

  Furthermore, as shown in FIGS. 3 to 5, the order of the reactor 72 and the diode 73 constituting the second smoothing means 7 may be any.

  About the power converter device comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  FIG. 2 is an operation waveform of each part in the present embodiment. First, the operation of the conventional power conversion device will be described.

  When a commercial power supply with an AC power supply frequency fac = 50 Hz or 60 Hz is used as the AC power supply 1, the output voltage waveform is a sine wave waveform with a period Tac = 20 msec or 16.7 msec as shown in FIG. When this is full-wave rectified by a rectifier 2 composed of a diode bridge in which a plurality of diodes are combined, a full-wave rectified waveform pulsating at a cycle Tac / 2 that is half the power cycle as shown in FIG. . Next, the full wave rectified waveform is smoothed by the smoothing means 3.

  Here, the values of the reactor 32 and the capacitor 31 constituting the smoothing means 3 are set so that the resonance frequency fc = 1 / (2π * √ (L1C1)) is 40 times or more the AC power supply frequency fac. For example, when the AC power supply frequency fac = 50 Hz, by using the reactor 32 and the capacitor 31 having a reactance value of 0.5 mH and a capacitance value of 10 μF, fc (= 2250 Hz)> 40 * fac (= 50 Hz).

  As shown in FIG. 2 (c), the smoothing voltage pulsates greatly at a period Tac / 2 that is half of the AC power supply period as shown in FIG. Since the energization width of the AC input current is wide as shown in FIG. 2 (h), high performance of the high input power factor and power supply harmonic characteristics can be realized.

  Here, by using a film capacitor instead of an electrolytic capacitor generally used for smoothing as the capacitor 31 constituting the smoothing means 3, even if the capacitor 31 is repeatedly charged and discharged with a large pulsating voltage, capacity loss due to self-heating and life characteristics are obtained. In addition, it is possible to reduce deterioration in the temperature environment and relax restrictions on the temperature environment in consideration of life characteristics. A stable drive of the compressor motor 6 can be realized by receiving a command for driving the motor from the control means 5 and operating the orthogonal transform means 4 in response to the large pulsating smooth voltage.

  However, since the control means 5 is composed of a constant voltage driving element such as a microcomputer, it is necessary to supply and operate a stable DC voltage.

  Further, when the DC fan motor 11 is driven separately from the compressor motor 6, when the command corresponding to the voltage that pulsates greatly is given from the control means 5 to the orthogonal transform means 9 as in the case of driving the compressor motor, the control means 5 is Since an excessive load is imposed on the processing capability of the microcomputer to be configured, it is necessary to use a high-performance and expensive microcomputer or to use a plurality of microcomputers. For this reason, in order to use a microcomputer equivalent to the conventional control means 5, it is necessary to supply a stable DC voltage to the orthogonal transformation means 9 for driving the DC fan motor.

However, since the output voltage from the smoothing means 3 in the conventional power conversion apparatus pulsates greatly, the SW power supply means 10 for operating the control means 5 as it is or the orthogonal conversion for driving the DC fan motor. It cannot be supplied to the means 9.

  Therefore, the smoothing voltage is further smoothed by the second smoothing means 7 that smoothes the smoothing voltage by the capacitor 71 via the diode 73 and the reactor 72, so that the power supply configuration to the compressor motor 6 is maintained as it is in FIG. A stable DC voltage free from pulsation as shown in FIG.

  Here, the capacitor 71 constituting the second smoothing means 7 uses a capacitor having a large capacity (for example, 150 μF) in order to obtain a stable DC voltage without pulsation even when the DC fan motor is driven. The peak value Ipeak1 of the inrush charging current is as shown in FIG. When this current is superimposed on the AC input current, the AC input current is as shown in FIG. 2 (f), leading to a decrease in input power factor and a decrease in power supply harmonic characteristics.

  In order to prevent such a situation, the second rectifier (diode) 73 and the reactor 72 are connected to the charging path to the capacitor 71 constituting the second smoother 7. By setting a reactance value (for example, 19 mH) of the reactor 72 that can sufficiently reduce the peak value Ipeak2 (<Ipeak1) of the inrush current, the inrush charging current and the AC input current to the capacitor 71 are suppressed in FIG. As shown in g) and (h), high input power factor and high performance of the power supply harmonic characteristics can be maintained.

  At this time, although the capacitance value of the capacitor 71 constituting the second smoothing means 7 and the reactance value of the reactor 72 are larger than those constituting the smoothing means 3, the DC fan motor is compared with the case where the compressor motor 6 is driven. 11 and the drive control means 5 are operated, the current capacity supplied becomes small. For this reason, the current capacities of the capacitor 71 and the reactor 72 can be set low, and the size and cost of the entire apparatus can be reduced as in the conventional case.

  As described above, the present embodiment includes the second smoothing means 7 for smoothing the pulsating output voltage from the smoothing means 3 with the capacitor 71 via the second rectifying means (diode) 73 and the reactor 72. The power supply configuration of the conventional power conversion device is used to reduce the size and cost of the entire device, while realizing stable operation of the control means 5 and driving of the DC fan motor 11 by DC power supply, and a higher input power factor In addition, high performance of power supply harmonic characteristics can be realized.

  As described above, since the power conversion device according to the present invention can obtain a stable DC voltage from a smooth pulsating smooth voltage, it has a plurality of power loads and needs to supply a stable DC voltage. It can be applied to all power conversion devices.

Configuration diagram of power conversion device according to Embodiment 1 of the present invention (A)-(h) is each part operation waveform figure of the power converter Configuration diagram of other power converters Configuration diagram of other power converters Configuration diagram of other power converters Configuration diagram of conventional power converter

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectification means 3 Smoothing means 4 Orthogonal transformation means 5 Drive control means 6 Motor, compressor motor 7 Second smoothing means 8 DC load 9 Orthogonal transformation means 10 SW power supply means 11 DC fan motor 12 Air conditioner 31 Capacitor 32 reactor 71 capacitor 72 reactor 73 diode

Claims (7)

Rectifying means for full-wave rectification of the AC power supply, first smoothing means for setting a value so that the output voltage from the rectifying means pulsates at twice the frequency of the AC power supply frequency, and output from the first smoothing means A power converter comprising a load supplied with power and a control means for controlling the load, and further comprising a second smoothing means for smoothing an output voltage of the first smoothing means. 2. The power converter according to claim 1, wherein the second smoothing means comprises at least an inductance, a capacitor, and a second rectifying means. The power converter according to claim 2, wherein the second rectifying means is constituted by a diode. The power converter according to any one of claims 1 to 3, wherein an output from the second smoothing means is supplied to the control means. The first smoothing means includes a capacitor and a reactor, and a resonance frequency embodied by the capacitor and the reactor is set to be 40 times or more of an AC power supply frequency. The power conversion device according to item 1. The power converter according to any one of claims 1 to 5, wherein a film capacitor is used as the capacitor constituting the first smoothing means. The air conditioner which comprises the power converter device of any one of Claims 1-6.

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