JP2006121837A - Power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply, having a high output voltage and a high power factor and suppressing higher harmonics, using a simple structure. <P>SOLUTION: The power supply is provided with an AC power supply 1; a bridge rectifying circuit 6 using four diodes; a capacitor 10, wherein a smoothing capacitor 7 is connected to the DC output end of the bridge rectifying circuit 6, and reactors 8, 9 are connected in series between the AC power supply 1 and the AC input end of the bridge rectifying circuit 6, is connected between the AC input end and the DC output end of the bridge rectifying circuit 6, on a side where the reactors 8, 9 are connected via a bidirectional switch 11; a bidirectional switch 12 for opening/closing the connection between the connection points of the reactors 8, 9 and the AC input end of the bridge rectifying circuit 6; a zero-cross detection means 14 for detecting the voltage of the AC power supply 1; a bidirectional switch drive signal generating means 15 for generating the drive signal of the bidirectional switch 11, based on the output; and a bidirectional switch drive means 16 for driving the bidirectional switch 11, based on the signal of the bidirectional switch drive signal generating means 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power supply device that uses a rectification method using a bridge rectifier circuit and supplies power to a device, a system, or the like with high power factor and low distortion.

  As a conventional power supply device that realizes low distortion with high power factor and suppressed harmonics, a device in which a capacitor is added to a full-wave rectifier circuit has been devised (see, for example, Patent Document 1).

  FIG. 6 shows a conventional power supply device described in Patent Document 1. In FIG. As shown in FIG. 6, a bridge rectifier circuit 6 composed of an AC power source 1, diodes 2 to 5, a smoothing capacitor 7, a reactor 8, a bidirectional switch 11, a capacitor 10, and a zero-cross detection means 14 The bidirectional switch drive signal generating means 15 and the bidirectional switch drive means 16 are configured.

  FIG. 7 is an operation waveform of each part of the conventional power supply device. The operation will be described with reference to FIG.

  When the bidirectional switch 11 is turned on with a delay of Δd from the zero cross point in the positive half cycle of the alternating voltage, the alternating current power supply 1-the reactor 8-the diode 2-the smoothing capacitor 7-the bidirectional switch 11-the capacitor 10-alternating current A series resonance current flows through the path of the power source 1, and the charge of the capacitor 10 is discharged to the smoothing capacitor 7.

  When the bidirectional switch 11 is turned off Δt after the bidirectional switch 11 is turned on, the current flowing through the reactor 8 is continued through the diodes 2 and 5 as a normal full-wave rectification operation. Next, in the negative half cycle of the AC voltage, when the bidirectional switch 13 is turned on with a delay of Δd from the zero cross point, the AC power source 1 -capacitor 10 -bidirectional switch 11 -diode 3 -reactor 8 -AC power source 1 The charging current flows through the capacitor 10 through the path.

  When the bidirectional switch 11 is further turned off after Δt, the current flowing through the reactor 8 is continued through the diodes 4 and 3 as a normal full-wave rectification operation.

In the above configuration and operation, the inductance of the reactor 8 and the capacitance of the capacitor 10 are appropriately selected, and the Δd and Δt are appropriately set according to the load, thereby realizing a high power factor while suppressing harmonics. At the same time, the DC output voltage can be controlled by the boosting action of the reactor 8 and the capacitor 10.
JP 2002-223571 A

  However, the conventional power supply apparatus as described above has good characteristics with a relatively small capacity power supply apparatus, but there is a problem that the DC output voltage and the power factor decrease when the capacity of the power supply is increased. Was.

  In particular, in order to realize a large-capacity power supply that satisfies the IEC harmonic regulations, it is necessary to increase the inductance of the reactor 8. As a result, the voltage drop due to the reactor 8 increases, the DC output voltage decreases, and the input current and There has been a problem that the power factor decreases due to an increase in the phase shift of the power supply voltage.

  The power supply device of the present invention solves the conventional problems as described above, and an object thereof is to provide a power supply device that can suppress a decrease in DC output voltage and power factor even at high output.

  In order to solve the above problems, a power supply device of the present invention includes a bridge rectifier circuit that constitutes a plurality of reactors and a single-phase full-wave rectifier circuit, and connects an intermediate connection point of the plurality of reactors and an AC input terminal of the bridge rectifier circuit. It has a configuration in which connection is made via two bidirectional switches.

  According to the power supply device as described above, the circuit operation is equivalent to the case where the inductance of the reactor is reduced by closing the second bidirectional switch at the time of high output, and the voltage drop and current phase shift due to the reactor are suppressed. Therefore, the output voltage and power factor can be prevented from decreasing.

  The power supply apparatus according to the present invention can suppress a decrease in the DC output voltage and the power factor even during large output while performing output voltage control.

  The present invention provides an AC power supply, a bridge rectifier circuit formed by four diodes for full-wave rectification of AC from the AC power supply, an electrolytic capacitor for smoothing the output of the bridge rectifier circuit, the AC power supply, and the A plurality of reactors connected in series between the AC input terminal of the bridge rectifier circuit, and a capacitor connected via a first bidirectional switch between the AC input terminal and the DC output terminal of the bridge rectifier circuit A second bidirectional switch that opens and closes a connection between a connection point between the plurality of reactors and an AC input terminal of the bridge rectifier circuit; and a zero-cross detection unit that detects a zero point of the voltage of the AC power supply. A bidirectional switch drive signal generating means for generating a drive signal for the first bidirectional switch based on an output of the zero cross detecting means; and the bidirectional switch drive signal generating By providing the bidirectional switch driving means for driving the first bidirectional switch based on the stage signal, the effect equivalent to the reduction of the inductance of the reactor can be obtained at the time of large output, and the DC output voltage and the power factor decrease. Can be suppressed.

  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)
1A to 1D are configuration diagrams of a power supply device according to Embodiment 1 of the present invention. In FIG. 1, the same reference numerals are used for the same components as in FIG. 6, and FIGS. 1A to 1D operate in the same way, so only FIG.

  In FIG. 1A, a bridge rectifier circuit 6 has a configuration in which four diodes 2 to 5 are connected to form a single-phase full-wave rectifier circuit. In addition to the reactor 8, a reactor 9 is inserted in series with the reactor 8 and in an AC line to which a capacitor 10 is connected. A connection point between the reactors 8 and 9 and a connection point between the reactor 9 and the bidirectional switch 11 are connected via a second bidirectional switch 12.

  The inductances of the reactors 8 and 9 and the capacitance of the capacitor 10 are such that when the first bidirectional switch 11 is appropriately turned on / off according to the output as described below, the harmonics of the input current are IEC harmonics. It is preset to a value that clears the regulations.

The inductance of the reactor 8 is set to a value smaller than the inductance of the reactor 9.

  The circuit operation of FIG. 1A in the above configuration will be described.

  First, in a region where the output is relatively small, the second bidirectional switch 12 is turned off and the same operation as that of the conventional power supply device is performed.

  At this time, as shown in FIG. 7, the ON time of the first bidirectional switch 11 is relatively short, and the voltage Vc of the capacitor 10 is also in a state of being DC biased with little fluctuation.

  As the output increases, Δd in FIG. 7 is decreased and Δt is increased in order to suppress harmonics and maintain the DC output voltage.

  When the output further increases, Δd = 0, and the first bidirectional switch 10 is turned on from the zero crossing of the voltage.

  As the output increases, the fluctuation range of the voltage Vc of the capacitor 10 increases, and eventually fluctuates between zero and the DC output voltage Vo.

  2 (a) and 2 (b) are operation waveform examples of each part when a relatively large output is output with the second bidirectional switch 12 still turned off. The power supply voltage is 230V, 50Hz, the reactor 8 The inductance is 5 mH, the inductance of the reactor 9 is 13 mH, the capacitance of the smoothing capacitor 7 is 3300 μF, the capacitance of the capacitor 12 is 100 μF, and the input power is 3.5 kW.

  At this operating point, the DC output voltage is about 267 V and the power factor is 96%, which is a good characteristic.

  Further, the harmonic of the input current is also lower than the IEC harmonic regulation value 17 as shown in FIG.

  FIG. 3A shows the input current IL8 and the DC output voltage Vo when the load is further increased in this state and the input power reaches 5.0 kW.

  At this operating point, the DC output voltage is significantly reduced to about 200 V. For example, when this power supply device is used as a DC motor drive power supply, the desired maximum motor speed cannot be obtained. It is possible that this will occur.

  Further, the input current IL8 is greatly out of phase with the power supply voltage Vi, and as a result, the power factor is greatly reduced to about 79%.

  Accordingly, in the conventional circuit configuration, the output range is practically suppressed to a smaller value, which causes a problem that the output cannot be expanded.

  Here, when the second bidirectional switch 12 is turned on at the voltage zero-crossing point, almost no current flows through the reactor 9 and the reactor 9 is bypassed, and the reactor inductance is apparently reduced. Become.

  Details of this operation will be described with reference to FIGS. 1A, 3B, and 3C.

First, when the first bidirectional switch 11 is turned on in the positive half cycle of the AC power supply 1, the AC power supply 1-reactor 8-second bidirectional switch 12-first bidirectional switch 11-capacitor 10-diode. 5- A charging current flows through the capacitor 10 through the path of the AC power source 1.

  Next, when the first bidirectional switch 11 is turned off, a current path of AC power source 1-reactor 8-second bidirectional switch 12-diode 2-smoothing capacitor 7-diode 5-AC power source 1 is formed, Most of the current flowing from the AC power supply 1 passes through this path.

  As a result, most of the current flowing from the AC power source 1 passes through the second bidirectional switch 12, and the current flowing through the reactor 9 becomes a very small value (see FIG. 3C).

  When the first bidirectional switch 11 is turned on in the negative half cycle of the AC power supply 1, the AC power supply 1-diode 4-smoothing capacitor 7-capacitor 10-first bidirectional switch 11-second bidirectional The electric charge of the capacitor 10 is discharged to the smoothing capacitor 7 through the path of the switch 12 -reactor 8 -AC power supply 1.

  Next, when the first bidirectional switch 11 is turned off, a current path of AC power source 1-diode 4-smoothing capacitor 7-diode 3-second bidirectional switch 12-reactor 8-AC power source 1 is formed. Most of the current that flows from the power supply 1 passes through this path.

  As a result, most of the current flowing from the AC power source 1 passes through the second bidirectional switch 12, and the current flowing through the reactor 9 becomes a very small value (see FIG. 3C).

  With the above operation, the current waveform of the reactor 8 becomes IL8 shown in FIG. 3, the current of the reactor 9 becomes IL9, and the current of the second bidirectional switch 12 becomes almost the same as the current waveform of the reactor 8. Here, as described above, the current of the reactor 9 becomes a very small value when the second bidirectional switch 12 is turned on. This means that when the second bidirectional switch 12 is turned on, the reactor 9 is bypassed, and the action of its inductance component has almost disappeared. As a result, the output as shown in the waveform of FIG. The voltage Vo maintains a high value of about 267V.

  Further, since there is no phase shift between the power supply voltage Vi and the input current IL8, the power factor is as high as about 94%.

(Embodiment 2)
In the second embodiment, the inductance value is set so that the inductance value of the reactor 8 of the first embodiment is smaller than the inductance value of the reactor 9.

  In the circuit configuration of the first embodiment, the reactors 8 and 9 are equivalent to one reactor with the inductance added when the second bidirectional switch 12 is turned off at the small to medium output.

  On the other hand, when the second bidirectional switch 12 is turned on, the current flowing through the reactor 9 is very small as described above, so that the current flowing through the reactor 9 can be kept lower than the current flowing through the reactor 8. .

  Therefore, in this embodiment, as described above, the inductance of the reactor 8 is set to 5 mH, the inductance of the reactor 9 is set to 13 mH larger than the reactor 8, and the total inductance value of both reactors is secured to 18 mH.

Thus, by setting the inductance of the reactor 8 having a large current low and setting the inductance of the reactor 9 having a relatively small current large, the reactor 8 can be downsized.

(Embodiment 3)
In the third embodiment, the second bidirectional switch 12 of the first embodiment is opened when the current flowing through the reactor 9 becomes zero. When the output required for the power supply device becomes low, the second bidirectional switch 12 is turned off when the current of the second bidirectional switch 12 becomes zero.

  By this operation, it is possible to avoid the occurrence of a voltage surge due to a sudden change in the current flowing through the reactors 8 and 9.

(Embodiment 4)
FIG. 4 shows a configuration diagram of the second bidirectional switch 12 of the first embodiment of the power supply device according to the fourth embodiment of the present invention.

  In FIG. 4, a third bidirectional switch 18 is connected in series to a snubber circuit 21 in which a snubber resistor 19 and a snubber capacitor 20 are connected in series, and these are connected in parallel to the second bidirectional switch 12. ing.

  When the output required for the power supply device is low, the third bidirectional switch 18 is turned on simultaneously with the second bidirectional switch being turned off. The loop current flowing through the reactor 9 of the first form and the second bidirectional switch is attenuated by the snubber circuit 21, and when the loop current becomes zero, the third bidirectional switch 18 is turned off.

  With this operation, a voltage surge generated from the reactor 9 can be avoided even if the second bidirectional switch is turned off at an arbitrary phase instead of the zero cross point of the voltage.

(Embodiment 5)
In the fifth embodiment, the second bidirectional switch 12 of the first embodiment is turned off after a predetermined time elapses from the zero cross point of the voltage of the AC power supply 1 to the second bidirectional switch 12 until the current becomes zero. I have to.

  The current flowing through the second bidirectional switch 12 is substantially the same as IL8 in FIG. 3B, and becomes zero in the second half of the AC half cycle.

  An appropriate timing is set in the current zero period, and the second bidirectional switch 12 is turned off after a predetermined time elapses from the voltage zero crossing point to the set timing.

  Since the zero-cross point of the voltage is necessary for the control of the bidirectional switch 11, the detection means is already provided. By using the control, the second bidirectional switch 12 can be easily controlled without adding any parts. It is possible to turn off in the section where the current becomes zero, and it is possible to avoid the occurrence of a surge voltage due to a sudden change in the current of the reactors 8 and 9.

(Embodiment 6)
In the sixth embodiment, the second bidirectional switch 12 in the first embodiment is configured by a triac.

With the above configuration, even if the second bidirectional switch 12 is turned off at an arbitrary timing, it is actually turned off when the current becomes zero, and generation of a surge voltage in the reactors 8 and 9 can be avoided. The controllability of the second bidirectional switch 12 is improved.

(Embodiment 7)
In the seventh embodiment, the reactor 8 has saturable characteristics, and as shown in FIG. 5, 5 mH is secured when the current flowing through the reactor 8 is smaller than the predetermined value ILo, and when the current becomes larger than the predetermined value ILo, the inductance is increased. The characteristic is to decrease.

  By providing this characteristic, it is possible to secure sufficient inductance to suppress power supply harmonics in the small to medium power region, and the inductance decreases in the large power region, so that the voltage drop and current phase of the reactor 8 are reduced. The shift is suppressed, which is advantageous for increasing the output.

  Further, since the maximum energy accumulated in the reactor 8 can be reduced, the reactor 8 can be downsized.

  As described above, since the power supply apparatus according to the present invention can achieve both a high power factor at the time of high output and output voltage maintenance, it can also be applied to applications such as a high output inverter air conditioner.

Configuration diagram of power supply device according to Embodiment 1 of the present invention The operation waveform diagram of each part at the time of relatively large output of the power supply device according to Embodiment 1 of the present invention, and a diagram showing a comparison between harmonic components and IEC harmonic regulation values (A) is a figure which shows the input current waveform and output voltage waveform at the time of the large output of the conventional power supply device, (b), (c) is an operation waveform figure of each part at the time of the large output of the power supply device in Embodiment 1 of this invention. The block diagram of the 2nd bidirectional switch in Embodiment 4 of this invention The characteristic diagram of the current and inductance of reactor 8 in the seventh embodiment of the present invention Configuration diagram according to an example of a conventional power supply device The figure which shows the comparison of each part operation waveform and harmonic component which concern on an example of the conventional power supply device, and a harmonic regulation domestic guideline

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2-5 Diode 6 Bridge rectifier circuit 7 Smoothing capacitor 8 1st reactor 9 2nd reactor 10 Capacitor 11 1st bidirectional switch 12 2nd bidirectional switch 13 Load 14 Zero cross detection means 15 Bidirectional switch Drive signal generation means 16 Bidirectional switch drive means 17 IEC harmonic regulation value 18 Third bidirectional switch 19 Snubber resistance 20 Snubber capacitor 21 Snubber circuit

Claims (7)

An AC power source, a bridge rectifier circuit formed by four diodes for full-wave rectification of AC from the AC power source, an electrolytic capacitor for smoothing the output of the bridge rectifier circuit, the AC power source and the bridge rectifier circuit A plurality of reactors connected in series between the AC input terminal, a capacitor connected via a first bidirectional switch between the AC input terminal and the DC output terminal of the bridge rectifier circuit, and the plurality A second bidirectional switch for opening and closing a connection between the connection points of the reactors and the AC input terminal of the bridge rectifier circuit, a zero-cross detection means for detecting a zero point of the voltage of the AC power supply, and the zero-cross detection A bidirectional switch drive signal generating means for generating a drive signal for the first bidirectional switch based on an output of the means; and a signal of the bidirectional switch drive signal generating means Power supply being characterized in that a bidirectional switch driving means for driving on the basis of the first bidirectional switch. The plurality of reactors are set so that the total inductance value of the reactor on the AC power supply side from the connection point of the second bidirectional switch is smaller than the total inductance value of the reactor on the other side. The power supply device according to claim 1, wherein the power supply device is characterized. 3. The power supply device according to claim 1, wherein the second bidirectional switch is opened when a current flowing through the reactor becomes zero. 4. A snubber circuit formed by a snubber resistor and a snubber capacitor, and a circuit in which the snubber circuit and a third bidirectional switch are connected in series are configured in parallel with the second bidirectional switch. The power supply device according to claim 1 or 2. 3. The power supply device according to claim 1, wherein the second bidirectional switch is opened after a predetermined time has elapsed from a zero cross point of the AC power supply. The power supply device according to claim 1, wherein the second bidirectional switch is configured by a triac. The power supply device according to any one of claims 1 to 6, wherein a saturable characteristic is given to a reactor on the AC power supply side among the plurality of reactors.

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