JP3871738B2 - Power supply - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a power supply apparatus in which a leakage transformer is interposed between an AC power supply and a switching power supply unit.
[0002]
[Prior art]
  Conventional leakage transformers are mainly used in power supply units such as welding devices and discharge lamp devices.
  Since these devices are often short-circuited or close to the state during operation or at the start, as a safety measure against overload, a decrease in the output voltage on the secondary side accompanying an increase in load current is compared to a normal transformer. It uses the property of a leakage transformer that is far larger.
[0003]
  Therefore, the conventional leakage transformer includes a primary winding 31 and a secondary winding wound separately from each other at the center leg of the core 30 as shown in side and top views in FIGS. An output current is obtained by inserting two pass cores 33 and 34 each having an I-shaped core between windings 32 and having an appropriate thickness, and reducing the degree of coupling between the primary and secondary sides. Only the drop characteristic of the output voltage is regarded as important, and the value of the primary or secondary leakage inductance or the value of the equivalent leakage inductance viewed from the primary side or the secondary side is not considered to be a problem. It was.
[0004]
  Therefore, since the value of these leakage inductances is completely unknown on the catalog of the conventional leakage transformer, it is not managed in production.what ifEven when the value of the leakage inductance was measured, the variation among individual products was extremely large. Furthermore, since a general power supply device is required to have a small variation in output current vs. output voltage characteristics, a leakage transformer having a large voltage variation has not been used.
[0005]
  On the other hand, a primary DC power is input and switched, for example, a DC-DC converter that converts to a constant DC voltage-controlled secondary DC power, or a DC-AC converter that converts a frequency-controlled secondary AC power, for example. A power supply device provided with a switching converter has been widely used because it is smaller and lighter and has a lower cost than its power capacity.
[0006]
  However, a power supply device provided with a switching converter has far higher power efficiency than a power supply device provided with a dropper or the like, for example. In addition, when converting AC power input from an AC power source to primary DC power, if a capacitor input type smoothing circuit is used, noise in the low frequency region increases with a decrease in power factor. There is a problem in Europe that it is not possible to comply with EMI regulations such as FCC and CISPR that are enforced from 1998.
[0007]
  Therefore, for example, in a power supply device having a switching power supply unit composed of a switching converter with a relatively small output having an output capacity of 200 W or less and a primary rectifying / smoothing circuit, as shown in FIG. An inductor system in which an inductor 42 is connected in series with a diode bridge 41 is adopted for an AC power line input via the power source, and the peak current is suppressed to improve the power factor and the harmonic current is reduced to reduce the harmonics. There was one that cleared the wave current regulation.
[0008]
  Further, for example, in a power supply device having a medium or large output switching converter with an output capacity exceeding 200 W, an active filter 43 is provided instead of a normal primary rectifying and smoothing circuit as shown in FIG. 1 through the insulation transformer 40 and the noise filter (NF) 44 is an alternating current of AC voltageAbsolute valueThere is a so-called two-converter type in which the power factor is improved to about 100% and the harmonic current in the low frequency region of the power supply frequency system is greatly reduced.
[0009]
  Alternatively, the primary rectification smoothing circuit shown in FIG. 11 except for the smoothing capacitor, the primary DC power that is just full-wave rectified can be directly input to the switching converter as it is, or the primary DC power line. A switching element is connected in parallel with a series circuit of a primary winding and a capacitor of a transformer of a switching converter, and a primary direct current via an inductor. Some have used a one-converter system with harmonic current countermeasures such as a boosting system that inputs power.
[0010]
[Problems to be solved by the invention]
  However, since the target of the inductor method is the harmonic of the power supply frequency in the low frequency range, it is necessary to increase the inductance value compared to the output capacity, the inductor becomes larger and heavier, and the cost also increases. Its use is limited to a small output power supply device, and is not practically applicable to a medium output or large output power supply device.
[0011]
  The two-converter system with an active filter is effective for improving the power factor and low-frequency harmonic current, but there are two switching elements that are independent of each other. In addition to an increase in the number of sources, there is a problem in that a wide band of complex noise is generated by interfering with each other, and that noise countermeasures are difficult and complicated and cost increases.
[0012]
  Alternatively, the one-converter system, in which the switching converter itself has EMI noise countermeasures, is still being developed in various ways, but the voltage applied to the switching element at the time of light load increases and exceeds the withstand voltage of the switching element. In addition, a system that has become the main switching power supply in which broadband noise is a problem has not yet been established, such as insufficient control capability because input current control and output voltage control are performed simultaneously in one switching. It's real.
[0013]
  The present invention has been made in view of the above points, and an object of the present invention is to provide a simple configuration, low cost, and effective EMI noise and input harmonic current countermeasures.
[0014]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention provides a 100V AC power source.Or 200V AC power supplyIn the power supply device for converting the AC power input from the switching power supply unit and outputting it, a leakage transformer is interposed between the AC power supply and the switching power supply unit, and the AC power supply is disposed on the primary side of the leakage transformer, Connect the switching power supply to the secondary side,When the AC power source is a 100V AC power source,The equivalent leakage inductance seen from the primary side of the leakage transformer is 5mH to 100mHTo be.
[0015]
  Also,When the AC power supply is a 200V system power supply, the equivalent leakage inductance viewed from the primary side of the leakage transformer is set to 50 mH to 250 mH.
[0016]
  And aboveLine bypass capacitors are connected between the primary or secondary terminals of the leakage transformer and between each terminal and ground, and the capacitance of each line bypass capacitor is equivalent to that seen from the primary or secondary side. A noise filter is formed by the leakage inductance.
  Each of the line bypass capacitors may be constituted by a parallel circuit of a low frequency capacitor and a high frequency capacitor.
[0017]
  OrIn a power supply device that converts AC power input from a 100V AC power supply or 200V AC power supply by a switching power supply unit and outputs the converted power,
A leakage transformer is interposed between the AC power supply and the switching power supply,
The AC power supply is connected to the primary side of the leakage transformer, and the switching power supply unit is connected to the secondary side.A line bypass capacitor is connected between the primary and secondary terminals of the leakage transformer and between each terminal and the ground, and the capacitance of each line bypass capacitor on the primary side and the primary leakage of the leakage transformer. The primary side noise filter may be formed by the inductance, and the secondary side noise filter may be formed by the capacitance of each secondary line bypass capacitor and the secondary leakage inductance of the leakage transformer.
[0018]
  In this case, the primary side noise filter may be a low frequency noise filter and the secondary side noise filter may be a high frequency noise filter.
[0019]
[0020]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be specifically described below with reference to the drawings.
  FIG. 1 illustrates the present invention.FoundationIt is a circuit diagram which shows an example of a structure of a power supply device. A power supply device 10 shown in FIG. 1 includes a leakage transformer 2 and a switching power supply unit 3, and AC power input from the AC power supply 1 to the primary side of the leakage transformer 2 is transmitted through the leakage transformer 2 to the secondary power. Is output to the switching power supply unit 3 from the side.
[0021]
[Expression 1]
      ELm1 = Lm1 + (N1 / N2) 2 × Lm2
      ELm2 = Lm2 + (N2 / N1) 2 × Lm1
[0022]
  Reference numerals N1 and N2 of the leakage transformer 2 indicate the primary side and secondary side windings as well as the number of turns thereof, and the primary and secondary windings N1 and N2 are insulated from each other. Symbols Lm1 and Lm2 indicate primary and secondary leakage inductances, respectively. Equivalent leakage inductances ELm1 and ELm2 viewed from the primary side or the secondary side are obtained by the equations shown in Equation 1, respectively. .
[0023]
  The switching power supply unit 3 includes a diode bridge 4 and a smoothing capacitor C0, a capacitor input type rectifying / smoothing circuit that converts AC power into primary DC power, and a secondary in which the primary DC power is controlled at a constant voltage. The switching converter 5 is a DC-DC converter that converts to DC power and outputs it to a load (not shown).
[0024]
  In general, since the primary DC power side and the secondary DC power side are insulated from each other by a high-frequency transformer (not shown) in the switching converter 5, AC power input from the AC power supply 1 leaks to the load to cause an electric shock. However, even if an accident occurs in which the high frequency transformer overheats due to overload or the like and the insulation is destroyed, the primary and secondary sides of the leakage transformer 2 are insulated from each other. There is no danger of serious accidents like
[0025]
  Further, unlike the conventional leakage transformer, the leakage transformer 2 is configured as described later, for example, by accurately managing the primary and secondary leakage inductances Lm1 and Lm2 so as to have preset values at the time of manufacture. It is also possible to accurately manage the values of the equivalent leakage inductances ELm1 and ELm2 as seen from the primary side and the secondary side obtained from the primary and secondary winding numbers N1 and N2 by Equation 1.
[0026]
  Moreover, the equivalent leakage inductance ELm1 obtained from the primary side thus obtained is set to 5 mH to 100 mH if the AC power supply 1 is a 100V system power supply, and 50 mH to 250 mH if the AC power supply 1 is a 200V system power supply, respectively. It is possible to effectively suppress noise in the low frequency range of the AC power supply frequency system including the higher harmonics and the high frequency range of the switching frequency system.
[0027]
  In order to enhance the noise suppression effect, it is clear that it is better to increase the value of the equivalent leakage inductance ELm1 (or ELm2) as seen from the primary side (similarly from the secondary side) As can be seen in the embodiments described later, if the equivalent leakage inductance is increased too much, the degree of coupling between the primary winding N1 and the secondary winding N2 decreases, and therefore the output voltage decreases with an increase in load current. There is a problem of growing.
[0028]
  Therefore, as a transformer used for a power supply device for general applications, an equivalent leakage inductance ELm1 viewed from the primary side is set to a range of 5 to 100 mH for a 100V system power supply and 50 to 250 mH for a 200V system power supply. It is a leakage transformer with the best balance in terms of both noise suppression effect and output voltage drop tolerance.
[0029]
  A line bypass capacitor was connected to the leakage transformer 2 in order to further improve the noise suppression effect without changing the output voltage fluctuation rate with respect to the load current.According to this inventionEmbodiments of the power supply device are shown in FIGS. Even if the line bypass capacitor is connected in this manner, the degree of coupling between the primary winding N1 and the secondary winding N2 of the leakage transformer 2 does not change, and the output voltage drop characteristic is affected by anything. There is nothing.
[0030]
  As shown in FIG.FirstThe power supply device 11 according to the embodiment has a line bypass capacitor connected to the primary side of the leakage transformer 2, and a series circuit of capacitors C11 and C12 and a capacitor C13 are connected between both terminals of the primary winding N1. Are connected in parallel, and an intermediate point between the capacitors C11 and C12 constituting the series circuit is connected to the ground (frame ground), and the same parts as those of the power supply apparatus 10 shown in FIG. Therefore, the description is omitted.
[0031]
  In general, a line bypass capacitor removes a symmetric component (reverse phase component) from noise superimposed on two connected lines by a capacitor C13, and drops the remaining asymmetric component to the ground via a capacitor C11 or C12, respectively. In the power supply device 11, the low-frequency region, the high-frequency region, or the low-frequency region is selected depending on the combination of the equivalent leakage inductance ELm 1 viewed from the primary side of the leakage transformer 2 and the capacitances of the capacitors C 11 to C 13. Band and high frequency band noise can be further greatly suppressed.
[0032]
  That is, by configuring each of the line bypass capacitors C11 to C13 with a low frequency capacitor or a high frequency capacitor having a much smaller capacitance, noise in a low frequency range or a high frequency range is combined with the equivalent leakage inductance ELm1. Can be suppressed. Furthermore, although it does not change as a circuit diagram, both the capacitors C11 to C13 are configured by a parallel circuit of a low-frequency capacitor and a high-frequency capacitor, so that both low-frequency and high-frequency noise can be suppressed.
[0033]
  As shown in FIG.SecondIn the power supply device 12 according to the embodiment, a line bypass capacitor is connected to the secondary side of the leakage transformer 2, and a series circuit of capacitors C21 and C22 and a capacitor C23 are connected between both terminals of the secondary winding N2. Are connected in parallel, and the intermediate point between the capacitors C21 and C22 constituting the series circuit is connected to the ground. The same reference numerals are used for the same parts as the power supply devices 10 and 11 shown in FIGS. A description thereof will be omitted.
[0034]
  The action and effect of the combination of the action of the capacitors C21 to C23 for line bypass and the equivalent leakage inductance ELm2 as seen from the secondary side is that the capacitors C21 to C23 and the equivalent leakage inductance ELm2 are respectively connected to the capacitors C11 to C13. If it is replaced with the equivalent leakage inductance ELm1, it is the same as that of the power supply device 11, and therefore detailed explanation is omitted.
[0035]
  As shown in FIG.ThirdThe power supply device 13 according to the embodiment has line bypass capacitors connected to the primary side and the secondary side of the leakage transformer 2, respectively, between both terminals of the primary winding N1 and the secondary winding N2. The series circuit of the capacitors C11 and C12 and the capacitor C13, and the series circuit of the capacitors C21 and C22 and the capacitor C23 are connected in parallel, respectively, and the intermediate points of the capacitors C11 and C12 and the capacitors C21 and C22 constituting the series circuit are grounded. The same parts as those of the power supply apparatuses 10 to 12 shown in FIGS. 1 to 3 are denoted by the same reference numerals and description thereof is omitted.
[0036]
  The power supply device 13 includes a noise filter composed of the primary side line bypass capacitors C11 to C13 and the leakage inductance Lm1, and a noise filter composed of the secondary side line bypass capacitors C21 to C23 and the leakage inductance Lm2, respectively. Needless to say, a higher noise suppression effect can be obtained as compared with the power supply apparatuses 11 and 12.
[0037]
  Further, for example, low frequency band noise can be shared by the primary side noise filter, and high frequency band noise can be shared by the secondary side noise filter.
  Since the band of the noise filter is not so strict, the equivalent leakage inductances ELm1 and ELm2 can be considered instead of the leakage inductances Lm1 and Lm2 combined with the primary side and secondary side line bypass capacitors, respectively. The practically the same effect can be obtained.
[0038]
  FIG. 5 shows an example of the configuration of a bobbin for winding that is fitted into the central leg of the core of the leakage transformer 2 used in the power supply devices 10 to 13 shown in FIGS. 1 to 4, and the primary wound around the bobbin. It is a figure shown with a coil | winding, a secondary winding, and the inserted path core, (A) of FIG. 5 has shown the longitudinal cross-sectional view of the bobbin, and (B) of the figure showed the top view, respectively.
[0039]
  The bobbin 20 shown in FIG. 5 has a hole 20h for fitting into the central leg of the core along the central axis, and three grooves 20a, 20b, and 20c surrounding the periphery perpendicular to the central axis. The primary winding 21 and the secondary winding in the grooves 20a and 20b, respectively.
A path core 23 made of a U-shaped core having a predetermined thickness regulated by its width is inserted into the groove 20c so as to be guided by the groove 20c and to be in a correct position. ing.
[0040]
  Therefore, the primary winding and the secondary winding are partially directly coupled by the leakage magnetic field lines deviated from the core (center leg) for magnetically coupling the primary winding 21 and the secondary winding 22. The path core 23 that suppresses the relative position is relatively correct with respect to the primary winding 21 and the secondary winding 22. That is, when assembling, the reproducibility of the primary and secondary leakage inductances Lm1 and Lm2 or the equivalent leakage inductances ELm1 and ELm2 is theoretically or experimentally set in advance, respectively. Therefore, the variation is extremely small as compared with the conventional leakage transformer shown in FIG.
[0041]
  FIG. 6 is a diagram showing another example of the configuration of the bobbin for winding. Unlike the integrally configured bobbin 20 shown in FIG.
  The bobbin shown in FIG. 6 is composed of first and second bobbins 25 and 26. FIG. 6A is a longitudinal sectional view showing the bobbins 25 and 26 combined, and FIG. The bottom view which shows the step 25d for guiding the path core of the bobbin 25 is shown, respectively.
[0042]
  As with the bobbin 20 (FIG. 5), the bobbins 25 and 26 each have holes 25h and 26h for fitting into the central leg of the core along the central axis, respectively, and surround the periphery thereof perpendicular to the central axis. The primary winding 21 and the secondary winding 22 are wound around the grooves 25a and 26b, respectively.
  In the step 25d of the bobbin 25, a pass core 23 made of a U-shaped core having a predetermined thickness regulated by its height is positioned between the bobbin 26 and the bobbin 26 so as to be guided by the step 25d to be in a correct position. Therefore, the operation and effect are the same as those of the bobbin 20 shown in FIG.
[0043]
  FIG. 7 is a plan view showing an example of the configuration of pass cores inserted in the groove 20c (FIG. 5) of the bobbin 20 or in the gap (FIG. 6) with the bobbin 26 generated by the step 25d of the bobbin 25, respectively. .
  7A shows an example of a path core composed of one core, and FIGS. 7B and 7C show examples of a path core composed of two cores.
[0044]
  As for the path core itself, two I-shaped cores may be arranged at symmetrical positions as in the conventional example shown in FIG. 10, but the U-shaped as shown in FIG. If the core 23 is used, only one core is required, so that parts management is easy and the number of assembly steps can be shortened. However, in order to keep the degree of coupling between the primary and secondary and the primary and secondary leakage inductances Lm1 and Lm2 from changing much, it is better to change the thickness compared to the case of two I-shaped cores. Good.
[0045]
  In addition, when covering between the primary and secondary windings with the pass core over the entire circumference of the central leg of the leakage transformer core, the leg is shortened as shown in FIG. 7 (B) or (C). If it is constituted by a combination of two U-shaped cores 23a or a combination of a U-shaped core 23 and an I-shaped core 24, the number of assembly steps can be reduced because only two cores are required. If any of them, the combination of the cores of the same type shown in FIG. 7B is easier in terms of component management.
[0046]
  In each path core shown in FIG. 7, the magnetic field lines always act in a direction perpendicular to the paper surface, and a magnetic path is not formed parallel to the paper surface, that is, along the path core. The size of the interval between the two cores combined only becomes a factor somewhat related to the degree of coupling between the primary and secondary and the primary and secondary leakage inductances Lm1 and Lm2, and has no other adverse effects.
[0047]
  FIG. 8 and FIG. 9 show the secondary voltage (output voltage) with respect to the primary voltage (input voltage) at no load and at the maximum load in the embodiment of the leakage transformer using the bobbin and the pass core as described above. FIG. 8 or FIG. 9 shows an example when the thickness of a path core obtained by symmetrically combining two I-shaped cores is set to 15 mm or 7 mm, respectively.
[0048]
  In FIG. 8, the secondary voltage output according to the primary voltage changed every 10V is indicated by a + mark when there is no load and a circle mark when the load is maximum.
  Also, in order to compare with the characteristics when a 15 mm-thick pass core is inserted, which is shown by connecting the same marks with solid lines, the characteristics when the pass cores are not inserted are connected with broken lines between the same marks. Show.
[0049]
  A leakage transformer for a 100V power supply with a 15 mm-thick pass core (characterized by a solid line) has an equivalent leakage inductance ELm1 as viewed from the primary side of approximately 100 mH, which improves noise, particularly in the low frequency range. In addition, as is clear from the characteristics at no load and at maximum load, the voltage drop ratio of the secondary voltage to the primary voltage and the voltage fluctuation rate with respect to the load are within a satisfactory level. . Note that a leakage transformer for a 200V system power supply under the same path core conditions also yielded an equivalent leakage inductance ELm1 of 212 mH within a range in which the voltage drop ratio and the voltage fluctuation rate were not problematic.
[0050]
  For reference, the characteristics without the pass core connected by a broken line are such that the voltage drop ratio (secondary voltage at no load / primary voltage value) is slightly larger than that with the pass core. There is a significant improvement in the voltage fluctuation rate (relative to the load). In other words, the leakage transformer feature is lost as much, and the primary and secondary leakage inductances Lm1 and Lm2 become small, and a value large enough to improve noise cannot be obtained.
[0051]
  The characteristics in the case where the thickness of the pass core shown in FIG. 9 is 7 mm, the voltage drop ratio and the voltage fluctuation rate are substantially intermediate between the presence and absence of the 15 mm-thick pass core, compared to the characteristics shown in FIG. (Preferably than with a pass core), and an equivalent leakage inductance ELm1 of 67 mH was obtained as a leakage transformer for a 100 V system power supply.
  Although characteristics are not shown, when the thickness of the pass core is set to 4 mm, an equivalent leakage inductance ELm1 of 52 mH is obtained.
[0052]
  In summary, the power supply apparatus according to the present invention is as follows.11˜13 is a low frequency region due to the equivalent leakage inductances ELm1 and ELm2 viewed from the primary side and the secondary side of the leakage transformer 2 by interposing the leakage transformer 2 between the AC power supply 1 and the switching power supply unit 3. In addition, it is possible to suppress high-frequency noise, particularly low-frequency input harmonic current noise, and in series with the (high-frequency) transformer in the switching power supply unit 3, either insulation is broken. Even so, the occurrence of electric shock accidents is prevented.
[0053]
  In particular, by setting the equivalent leakage inductance ELm1 viewed from the primary side of the leakage transformer 2 to 5 mH to 100 mH for a 100 V system power supply and 50 mH to 250 mH for a 200 V system power supply, noise, particularly in a low frequency range, is input. A value sufficient to improve the harmonic current noise can be obtained, and the voltage drop ratio and the voltage fluctuation rate can be within a practically satisfactory range.
  Further, noise filters are formed by providing line bypass capacitors C11 to C13 or C21 to C23 on the primary side, the secondary side or both sides of the leakage transformer 2, respectively.Because, Noise can be further suppressed.
[0054]
  Further, the path core of the leakage transformer 2 may be formed by two I-shaped cores as in the prior art, but one U-shaped core or a combination of two U-shaped cores or a U-shaped core. If it is composed of a combination of a letter-shaped core and an I-shaped core, the number of assembling steps can be shortened and parts management becomes easy.
[0055]
  Furthermore, if a guide such as the groove 20c of the bobbin 20 for winding or the step 25d of the double bobbins 25 and 26 is provided, the position can be determined easily and accurately when the pass core is inserted. In addition, the number of man-hours for assembly can be shortened, and variations in the values of the primary and secondary leakage inductances Lm1 and Lm2 can be reduced.
[0056]
【The invention's effect】
  As described above, the power supply device according to the present invention has a simple configuration and low cost, and has effective EMI noise and input harmonic current countermeasures.
[Brief description of the drawings]
FIG. 1 of the present inventionFoundationIt is a circuit diagram which shows an example of a structure of a power supply device.
[Figure 2]1st of this inventionIt is a circuit diagram which shows an example of a structure of the power supply device which is embodiment.
[Fig. 3]The second of the present inventionIt is a circuit diagram which shows an example of a structure of the power supply device which is embodiment.
[Fig. 4]The third of the present inventionIt is a circuit diagram which shows an example of a structure of the power supply device which is embodiment.
5 is a diagram showing an example of a configuration of a winding bobbin of the leakage transformer shown in FIGS. 1 to 4. FIG.
FIG. 6 is a view showing another example of the configuration of the winding bobbin of the leakage transformer.
7 is a plan view showing an example of the configuration of a pass core inserted into the winding bobbin shown in FIG. 5 or FIG. 6;
FIG. 8 is a diagram showing an example of a primary voltage vs. secondary voltage characteristic of a leakage transformer according to the present invention.
FIG. 9 is a diagram showing an example of a primary voltage vs. secondary voltage characteristic of a leakage transformer in which the thickness of the path core is changed.
FIG. 10 is a diagram showing a configuration of a conventional example of a leakage transformer.
FIG. 11 is a circuit diagram showing an example of a configuration of a conventional power supply device including an inductor in an input AC line.
FIG. 12 is a circuit diagram showing an example of a configuration of a conventional power supply device including an active filter on an input side.
[Explanation of symbols]
1: AC power supply 2: Leakage transformer
3: Switching power supply unit 4: Diode bridge
5: Switching converter
10-13: Power supply device 20, 25, 26: Bobbin
21: Primary winding 22: Secondary winding
C11 to C13: Line bypass capacitors on the primary side
C21 to C23: Secondary line bypass capacitors
ELm1: Equivalent leakage inductance viewed from the primary side
Lm1, Lm2: Primary or secondary leakage inductance

Claims (5)

In a power supply device that converts AC power input from a 100V AC power supply by a switching power supply unit and outputs it,
A leakage transformer is interposed between the AC power source and the switching power source unit,
The AC power supply is connected to the primary side of the leakage transformer and the switching power supply unit is connected to the secondary side, and the equivalent leakage inductance viewed from the primary side of the leakage transformer is 5 mH to 100 mH ,
A line bypass capacitor is connected between the primary or secondary terminals of the leakage transformer and between each terminal and the ground, and the capacitance of each line bypass capacitor is viewed from the primary side or the secondary side. A power supply device characterized in that a noise filter is formed by the equivalent leakage inductance . In a power supply device that converts AC power input from a 200V AC power supply by a switching power supply unit and outputs it,
A leakage transformer is interposed between the AC power source and the switching power source unit,
The AC power supply is connected to the primary side of the leakage transformer and the switching power supply unit is connected to the secondary side, and the equivalent leakage inductance viewed from the primary side of the leakage transformer is 50 mH to 250 mH ,
A line bypass capacitor is connected between the primary or secondary terminals of the leakage transformer and between each terminal and the ground, and the capacitance of each line bypass capacitor is viewed from the primary side or the secondary side. A power supply device characterized in that a noise filter is formed by the equivalent leakage inductance . 3. The power supply device according to claim 1, wherein each of the line bypass capacitors is constituted by a parallel circuit of a low frequency capacitor and a high frequency capacitor . In a power supply device that converts AC power input from a 100V AC power supply or 200V AC power supply by a switching power supply unit and outputs the converted power,
A leakage transformer is interposed between the AC power source and the switching power source unit,
The AC power supply is connected to the primary side of the leakage transformer, and the switching power supply unit is connected to the secondary side.
A line bypass capacitor is connected between each of the primary and secondary terminals of the leakage transformer and between each terminal and the ground, and the capacitance of each of the primary line bypass capacitors and one of the leakage transformers are connected. A primary side noise filter is formed by the secondary leakage inductance, and a secondary side noise filter is formed by the capacitance of each secondary line bypass capacitor and the secondary leakage inductance of the leakage transformer. Power supply. 5. The power supply apparatus according to claim 4 , wherein the primary-side noise filter is a low-frequency noise filter, and the secondary-side noise filter is a high-frequency noise filter .

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