JPS6057601B2 - DC power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a direct current power supply device that prevents harmonic current from flowing to an alternating current power source and simultaneously adjusts voltage.

As shown in FIG. 1, between AC power supply 1 and load 2, 4
a controlled rectifier consisting of three thyristors 3, 4, 5, 6;
If a smoothing circuit consisting of a reactor 7 and a capacitor 8 is provided and a controlled DC/current voltage or current is supplied to the load 2, the power supply voltage of the AC power supply 1 will be a sine wave as shown in Fig. 2A. In this case, the current is distorted and harmonic current flows as shown in FIG. 2B or C.

When harmonic current flows in this way, harmonic power is generated due to heat generated by generators and rotating machines connected to the AC power supply, overvoltage and overcurrent caused by resonance phenomena in the power system, and heat generated by power factor correction capacitors. cause trouble. This harmonic power disturbance can be prevented by connecting a filter to the power line, which naturally results in lower equipment power values.
SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a DC power supply device that can block harmonic currents while reducing costs.

A first invention of the present application for achieving the above object includes a first transformer having a primary winding connected between a first phase power line and a third phase power line of a three-phase AC power supply; 1 of the first transformer, which is connected between the second phase power line of the three-phase AC power supply and the midpoint of the primary winding of the first transformer.
a second transformer having a primary winding configured to have a number of turns of 00% of the number of turns of the secondary winding;
a first center-tapped full-wave rectifier circuit connected to the secondary winding of the first transformer; a first center-tapped full-wave rectifier circuit connected to the secondary winding of the first transformer; The tap-type full-wave rectifier circuit has a capacity capable of absorbing harmonic current generated when power is supplied to a load and preventing the harmonic current from spreading to the AC power source. 1st
a first reactor connected in parallel to the first capacitor via a first alternating current switch whose conduction angle can be controlled; a first reactor connected to the secondary winding of the second transformer; a second center-tap full-wave rectifier circuit whose output is coupled in parallel to the output of the first center-tap full-wave rectifier circuit; and a second center-tap full-wave rectifier circuit connected to the secondary winding of the second transformer. At the same time, the second center-tapped full-wave rectifier circuit absorbs harmonic current generated when power is supplied to the load and prevents the harmonic current from spreading to the AC power source. The second having the capacity possible
a second reactor connected in parallel to the second capacitor via a second alternating current switch whose conduction angle is controllable, and a voltage across the load or the first or second center tap. a voltage detection circuit that detects the input side voltage of the full-wave rectifier circuit; and a conduction angle control of the first and second AC switches so that the voltage becomes a predetermined value in response to the output of the voltage detection circuit. The present invention relates to a DC power supply device characterized by comprising a switch control circuit.

According to the present invention, since the capacitor used for voltage adjustment is used to block harmonic current, it is possible to block harmonic current at the same time as adjusting voltage, simplifying the device and reducing costs. It becomes possible to do so.

In addition, the first and second transformers are not only used in a center-tapped full-wave rectifier circuit, but also used to pass current to the first and second capacitors, and are also used for voltage regulation. Since it is used to provide a voltage drop and also to prevent harmonic current from flowing to the power supply side, the device can be significantly simplified. Furthermore, since a center-tap type full-wave rectifier circuit is used, the number of diodes is reduced, making it possible to reduce the cost of the device.
Furthermore, even if the secondary side has a two-phase configuration, one end of the primary winding of the second transformer is connected to the midpoint of the primary winding of the first transformer, creating a so-called Scott connection. The next side is in a state close to three phases, and the balance of each phase can be improved.
Also, the voltage of the secondary winding of the first transformer and the voltage of the secondary winding of the second transformer are
A phase difference of 90 degrees occurs between the voltage of the next winding, and this 90 degree
Since the first voltage and the second voltage, which have a phase difference of 100 degrees, are each subjected to full-wave rectification and then added together, it is possible to obtain a rectifier output with less pulsation. A second invention of the present application is a DC power supply device according to the first invention in which a reactor is added to each power line of a three-phase AC power supply. This invention also provides the same effects as the first invention. Further, since the reactor is used for both harmonic current blocking and voltage regulation, there is no need to increase the induction component of the transformer, and the configuration of the transformer becomes easier. Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 3 showing a charging DC power supply device according to an embodiment of the present invention, between a three-phase AC power supply 11 and a storage battery load 12, a first transformer 13, a second transformer 14, a A first center-tapped full-wave rectifier circuit 15 connected to a transformer 13, a smoothing reactor 17, and a smoothing capacitor 1
A smoothing circuit consisting of 8 is provided.

To explain these in more detail, 1 of the first transformer 13
The secondary winding 19 is connected between the first phase power line 20 and the third phase power line 22, and the primary winding 23 of the second transformer 14 is connected between the first phase power line 20 and the third phase power line 22.
It is connected between the phase power line 21 and the midpoint 24 of the primary winding 19 of the first transformer 13 . In addition, the primary winding 19 of the first transformer 13 and the primary winding 23 of the second transformer 14
The ratio of the number of turns to JSl is 2: JSl, that is, the number of turns of the primary winding 23 is 1.
What is the number of turns of the next winding 19? ] “It is configured to have a 00% yield.

Further, the voltage of the secondary winding 25 of the first transformer 13 and the voltage of the secondary winding 26 of the second transformer 14 are configured to have a phase difference of 90 degrees. The secondary winding 25 of the first transformer 13 is provided with a first terminal 27 , a second terminal 28 , a third terminal 29 , and a fourth terminal 30 . A diode 31 is connected to the second terminal 28 , a second diode is connected to the third terminal 29 , and an intermediate line 33 is connected to the third terminal 29 . It is formed. In addition, the second voltage boost terminal
A first capacitor is connected between the terminal 28 and the fourth terminal 30. A reactor 38 connected in parallel to the first capacitor 34 via thyristors 36 and 37 as a first AC switch 35 whose conduction angle can be controlled flows a delayed current in a controlled manner to adjust the voltage. There are things to do. Secondary winding 2 of second transformer 14
6 is similarly provided with a first terminal 39, a second terminal 40, a third terminal 41, and a fourth terminal 42, and this first terminal 39 is connected to a second center tap type full-wave rectifier circuit. A third diode 43 constituting the terminal 16 is connected to the second terminal 40, and a fourth diode 44 is connected to the second terminal 40.

Further, a second capacitor 45 is connected between the second terminal 40 and the fourth terminal 42. A second reactor 49 connected in parallel to this second capacitor 45 via thyristors 47 and 48 as a second AC switch 46 controls the delayed current in the same manner as the first reactor 38. It is used to adjust the voltage by flowing the current. In the device of this embodiment, the fifth harmonic current is blocked and absorbed depending on the induction components of the first transformer 13 and the second transformer and the first capacitor 34 and the second capacitor 45. Therefore, a first third harmonic absorption circuit consisting of a third harmonic absorption reactor 50 and a capacitor 51 for absorbing third harmonic current is connected in parallel to the capacitor 34, Further, a second third harmonic absorption circuit including a third harmonic absorption reactor 52 and a capacitor 53 is connected in parallel to the capacitor 45.

The first and second transformers 13 and 14 are not only configured to be used as transformers for the first and second center-tapped full-wave rectifier circuits 15 and 16, but also It is also configured to be used to flow a forward current in a boosted state to the capacitors 34 and 45, and is also used as a reactor for voltage regulation and harmonic current blocking by increasing the leakage magnetic flux to increase the induction component. It is also configured to act as a

Reference numeral 54 is a voltage detection circuit, which detects the output voltage of the rectifier circuits 15 and 16, that is, the load voltage.

A thyristor control circuit 55 is a circuit that controls the thyristors 36, 37, 47, and 48 so that the output voltage becomes a predetermined value.

Tertiary windings 56 and 57 for power supply voltage detection are also connected to this thyristor control circuit 55 in order to control the conduction angles of the thyristors 36, 37, 38, and 39 in synchronization with the voltage of the AC power supply 11. Since this control circuit 55 is a well-known thyristor conduction control circuit, detailed explanation will be omitted. Next, the operation of the above circuit will be explained.

If the output voltage increases for some reason while power is being supplied to the storage battery load 12 at a constant voltage, this will be detected by the voltage detection circuit 54 and the thyristors 36, 37, 47
, 48 are controlled by the control circuit 55, respectively, so that the conduction angles (conduction periods) of the thyristors 36, 37, 47, and 48 become large.

That is, the voltage of the secondary winding 25 of the first transformer 13 is as shown in FIG.
If the voltage of the secondary winding 26 of the second transformer 14 is the waveform shown in FIG. 4B and a voltage of 50 Hz is supplied, the conduction angle of the thyristors 36 and 37 is The control is performed as shown in FIG. 4D, and the thyristor 47,
Since the conduction angle of 48 is controlled as shown in FIG. 4E, when lowering the output voltage, the control is performed so that the T2 period and the T4 period become larger. If the conduction time of the thyristors 36, 37, 47, 48 becomes longer, the first
and the delayed current IL flowing through the second reactors 38 and 49
increases. On the other hand, the first and second capacitors 34, 4
Since a leading current flows through the first and second transformers 13 and 14, a composite current of the delayed current 1L and the leading current 10 flows in the first and second transformers 13 and 14 in addition to the load current. The voltage drop in the first and second transformers depends on the lagging current (1) and the leading current (2).In this case, the leading current (2) is approximately constant, so the larger the lagging current (1), the greater the voltage drop. As the delay current 1 becomes smaller, the voltage drop becomes smaller, so the load voltage increases and the thyristors 36, 37, 4
When the conduction angles 7 and 48 increase, the voltage drop at the first and second transformers 13 and 14 increases, and the AC voltage on the input side of the rectifier circuit and the DC voltage on the output side of the rectifier circuit decrease, and the voltage drops to a predetermined voltage value. approach.

When the output voltage drops below a predetermined voltage value, the operation is completely opposite to the above, and the thyristors 36, 37, 47, 48
The conduction angle of the first and second reactors 38 becomes smaller.
, 49 is limited, and the delay current 1, flowing through the first and second
The voltage drop at the transformers 13 and 14 is reduced, and the output voltage approaches a predetermined value.

By the way, if the leakage magnetic flux of the first and second transformers 13 and 14 is increased and the induced components are respectively 20n1] (for example, then the impedance ωL for the third harmonic (150Hz component) of the fundamental wave of 50Hz is 18 .85Ω, and the first and second capacitors 34 and 45 are each 600μF.
Then, the impedance-5 for the third harmonic is 1.77Ω, and ωL=0.094.

Therefore, most of the third harmonic current flows to the first and second capacitors 34 and 45, and almost no current flows to the AC power supply 11 side. Comparing ωL and 1/ωC for the 5th harmonic (250Hz component), lock/ωL=3.38×10−
3, and since 2d is small compared to ωL, most of the fifth harmonic flows to the first and second capacitors 34 and 45. This device further includes a reactor 5 for third-order harmonic absorption.
0, 52, and capacitors 51, 53, the reactors 50, 52 are set to L, and the capacitors 51, 53 are set to C.
Then, f=? for the third harmonic frequency f? 'A
Since it is set so that transformers 13 and 14
The third harmonic that could not be blocked and absorbed by the induced component and the capacitors 34 and 45 is completely removed, and the current of the AC power source becomes a sine wave. Of course, harmonic currents other than the third and fifth harmonic currents are also blocked and absorbed. As is clear from the above, in this embodiment, the first and second transformers 13 and 14 and the first and second capacitors 34 and 45 are used not only for voltage regulation but also for harmonic blocking. Therefore, harmonic power interference can be removed with a simple configuration.

For example, when the AC power supply 11 is an engine generator,
Since the current in the power supply is a sine wave, the rated capacity should be set to 30 to 4
It becomes possible to increase the amount by 0%. Furthermore, in the case of a commercial power supply, the influence of harmonic currents on various devices connected thereto can be removed. Furthermore, even if the secondary side has a two-phase configuration, one end of the primary winding 23 of the second transformer 14 is connected to the midpoint 24 of the primary winding 19 of the first transformer 13, resulting in a so-called Scott connection. Therefore, the primary side is in a state close to 3 phases. Therefore, it is possible to improve the balance of each phase. Also, the voltage of the secondary winding 25 of the first transformer 13 and the voltage of the second
A phase difference of 90 degrees occurs between the voltage of the secondary winding 26 of the transformer 14, and the first voltage and the second voltage with this 90 degree phase difference are each subjected to full wave rectification and added. As a result, the rectified output becomes as shown in FIG. 4C, and a rectifier output with less pulsation can be obtained. Also, a part of the secondary windings 25, 26 of the transformers 13, 14 are used to connect the center tap type full wave rectifier circuits 15, 16, and all of the secondary windings 25, 26 are used to connect the capacitors. 34 and 45 are connected, it becomes possible to apply a high voltage to the capacitors 34 and 45, and it becomes possible to reduce the capacitance of the capacitors 34 and 45.

Furthermore, since the transformer 13 is used for various purposes, the configuration of the device can be greatly simplified.

In addition, full-wave rectified output is obtained by the two sets of half-wave rectifier circuits as center-tapped full-wave rectifier circuits 15 and 16.
The number of diodes can be halved compared to a bridge type rectifier circuit.

Furthermore, since the transformers 13 and 14 are provided with tertiary windings 56 and 57 for synchronization detection, the configuration of the synchronization detection circuit can be simplified.

Furthermore, since the capacitors 34 and 45 are used, it is possible to improve the power factor.

Moreover, efficient voltage regulation becomes possible. Next, FIG. 5, which shows another embodiment of the present invention, will be described.

However, since the parts indicated by reference numerals 11 to 57 are substantially the same as those shown by the same reference numerals in FIG. 3, the explanation thereof will be omitted. In this embodiment, the first, second, and third phase power lines 20, 21, 22 connected to the three-phase AC power supply
, fourth, and fifth reactors 61, 62, and 63 are connected, respectively. These reactors 61, 62, 63
The voltage drop changes in accordance with the ratio of the leading current flowing through the first and second capacitors 34 and 45 and the lagging current flowing through the first and second reactors 38 and 49, and the harmonic current There is a device that prevents the AC from flowing to the AC power supply 11 side. Therefore, in this case, it is not necessary to rely solely on the induction components of the transformers 13 and 14 to prevent voltage drops and harmonic currents for voltage regulation, so the induction components of the transformer 13 should be made particularly large. Voltage regulation and harmonic current blocking are possible without any design. It also has the same effects as the first embodiment. Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be further modified. For example, voltage detection may be performed on the input side of the rectifier circuit 13. It is also applicable to detecting the load current and adjusting the voltage to perform constant current control. It is also applicable to load power supply devices other than storage batteries. Also, thyristor 36
, 37, 47, and 48 may be replaced with triacs or other switching elements. In addition, in the circuits of FIGS. 3 and 5, reactors 50, 52 for absorbing third harmonics,
Omitting capacitors 51 and 53, capacitors 34 and 45
The third harmonic, the fifth harmonic, and other harmonics may be removed by using the transformers 13 and 14. Further, the center-tap type full-wave rectifier circuits 15 and 16 may be connected not to the ends of the secondary windings 25 and 26 but to the center thereof. Also, capacitor 34
, 45 to the boosted winding, e.g. terminals 28 and 3.
0 and between the terminals 40 and 42. That is, a capacitor may be connected to both ends of a transformer having a center tap, and a rectifying diode may be connected to both ends of the transformer.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a conventional DC power supply device, FIG. 2 is a waveform diagram illustrating voltage and current waveforms in the circuit of FIG. 1, and FIG. 3 is a DC power supply device according to an embodiment of the present invention. 4 is a waveform diagram of each part of the circuit of FIG. 3, and FIG. 5 is a circuit diagram showing a DC power supply device according to another embodiment of the present invention.

Claims (1)

[Claims] 1. A first transformer having a primary winding connected between a first phase power line and a third phase power line of a three-phase AC power supply, and a second phase of the three-phase AC power supply. The power line is connected between the midpoint of the primary winding of the first transformer, and the number of turns is √3/2×100 percent of the number of turns of the primary winding of the first transformer. a second transformer having a primary winding configured as follows; a first center-tapped full-wave rectifier circuit connected to the secondary winding of the first transformer; The first center-tapped full-wave rectifier circuit, which is connected to the secondary winding of the transformer, absorbs harmonic currents generated when power is supplied to a load and converts the harmonic currents. a first capacitor having a capacitance capable of preventing the influence from spreading to the alternating current power supply; and a first capacitor connected in parallel to the first capacitor via a first alternating current switch whose conduction angle can be controlled. a second reactor connected to the secondary winding of the second transformer and whose output is coupled in parallel to the output of the first center-tapped full-wave rectifier circuit.
a center-tap type full-wave rectifier circuit connected to the secondary winding of the second transformer and supplying power to the load through the second center-tap type full-wave rectifier circuit; a second capacitor having a capacity capable of absorbing harmonic current generated in the AC power source and preventing the harmonic current from spreading to the AC power source; and a second AC switch whose conduction angle is controllable. a second reactor connected in parallel to the second capacitor via a second reactor; and a voltage detector that detects the voltage between both ends of the load or the input side voltage of the first or second center-tapped full-wave rectifier circuit. a circuit, and the first
and a switch control circuit that controls the conduction angle of the second AC switch. 2 The secondary winding of the first transformer has three terminals for connecting the first center-tap type full-wave rectifier circuit using a part thereof, and three terminals for connecting the first center-tap type full-wave rectifier circuit. and a terminal for supplying the first capacitor with a voltage higher than the voltage obtained by the winding used in the full-wave rectifier circuit, and the secondary winding of the second transformer is Three terminals for connecting the second center-tap full-wave rectifier circuit using a part of the voltage, and the voltage obtained at the winding used in the second center-tap full-wave rectifier circuit. 2. The DC power supply device according to claim 1, further comprising a terminal for supplying a voltage higher than that to the second capacitor. 3. A first transformer having a primary winding connected between a first phase power line and a third phase power line of the three-phase AC power supply, and a first transformer having a primary winding connected between the second phase power line of the three-phase AC power supply and the first It is connected between the midpoint of the primary winding of the transformer and is configured such that the number of turns is √3/2×100% of the number of turns of the primary winding of the first transformer. a second transformer having a primary winding; a first center-tapped full-wave rectifier circuit connected to the secondary winding of the first transformer; The first center-tapped full-wave rectifier circuit connected to the winding absorbs harmonic current generated when power is supplied to a load, and causes the harmonic current to spread to the AC power supply. a first reactor connected in parallel to the first capacitor via a first AC switch whose conduction angle can be controlled; a second center-tapped full-wave rectifier circuit connected to the secondary winding of the second transformer and whose output is coupled in parallel to the output of the first center-tapped full-wave rectifier circuit; The second center-tap type full-wave rectifier circuit is connected to the secondary winding of the second transformer and absorbs harmonic current generated when it is desired to supply power to the load. A second capacitor having a capacity that can prevent harmonic current from spreading to the AC power supply; and a second capacitor connected in parallel to the second capacitor via a second AC switch that can control the conduction angle. a second reactor connected in series to the first phase power line, a fourth reactor connected in series to the second phase power line, and a fourth reactor connected in series to the third phase power line. a fifth reactor; a voltage detection circuit that detects the voltage across the load or the input voltage of the first or second center-tap full-wave rectifier circuit; A DC power supply device comprising: a switch control circuit that controls conduction angles of the first and second AC switches so that the voltage becomes a predetermined value. 4 The secondary winding of the first transformer has three terminals for connecting the first center-tap type full-wave rectifier circuit using a part thereof, and three terminals for connecting the first center-tap type full-wave rectifier circuit. and a terminal for supplying the first capacitor with a voltage higher than the voltage obtained by the winding used in the full-wave rectifier circuit, and the secondary winding of the second transformer is The voltage obtained at the three terminals for connecting the second center-tap full-wave rectifier circuit and the winding used in the second center-tap full-wave rectifier circuit using a part of the voltage. 4. The DC power supply device according to claim 3, further comprising a terminal for supplying a voltage higher than that to the second capacitor.