JP3823322B2 - Distributed constant structure - Google Patents

Description

  The present invention relates to a distributed constant structure used in a switching power supply device.

  FIG. 17 shows a configuration of a flyback converter which is an example of a conventional switching power supply device.

In FIG. 17, an input power source Vin is connected to an X capacitor C6 and a line filter T2 that is a filter inductor, is connected to a diode bridge D3, and is connected to a bulk capacitor C5.
The voltage Vb of the bulk capacitor C5 is connected to one end of the primary winding N1 of the transformer T1, the other end of the primary winding N1 of the transformer T1 is connected to the drain voltage Vds of the switching element Q1, and the source of the switching element Q1 Is connected to a stable potential COM.

  The capacitor C1, the resistor R1, and the diode D1 constitute a CRD snubber circuit 10 that is a primary snubber circuit. The anode of the diode D1 is connected to the drain Vds of the switching element Q1, the resistor R1 and one end of the capacitor C1 are connected to the cathode of the diode D1, and the other end of the resistor R1 and the capacitor C1 is connected to the voltage Vb.

  The CRD snubber circuit 10 branches at the voltage Vds in the path from the primary winding N1 of the transformer T1 that is the main line to the drain of the switching element Q1.

The secondary winding N2 of the transformer T1 is connected to the output Vout via the rectifier circuit of the diode D2 and the smoothing circuit of the capacitor C4.
The series connection of the capacitor C2 and the resistor R2 forms a CR snubber circuit, which is a secondary snubber circuit, and is connected in parallel to the diode D2.

  The operation of the conventional example of FIG. 17 will be described. The input power source Vin is rectified by the diode bridge D3, smoothed by the bulk capacitor C5, and becomes the voltage Vb. The switching element Q1 turns on and off the voltage Vb applied to the primary winding N1 of the transformer T1. The voltage induced in the secondary winding N2 of the transformer T1 is rectified by the diode D2, smoothed by the capacitor C4, and becomes the output voltage Vout.

  The voltage Vds changes in a rectangular wave shape by turning on and off the switching element Q1. In addition, a surge occurs during turn-on and turn-off. The surge affects the parasitic inductance and parasitic capacitance of the transformer T1, the output capacitance and switching characteristics of the switching element Q1. The CRD snubber circuit 10 suppresses a voltage surge that occurs when the switching element Q1 is turned off.

  Specifically, when the switching element Q1 is on, the voltage Vds is low and the diode D1 is off. Next, when the switching element Q1 is turned off, the voltage Vds rises and a voltage surge is generated. When the voltage Vds rises, the diode D1 is turned on and the capacitor C1 is charged. The rise of the voltage Vds is suppressed by charging the capacitor C1. The electric charge of the capacitor C1 is discharged by the resistor R1.

  Part of the noise accompanying the on / off of the switching element Q1 is transmitted to the input power source Vin via the diode bridge D3, the line filter T2, and the X capacitor C6. The main inductance of the line filter T2 attenuates the common mode component of noise. The leakage inductance of the line filter T2 and the X capacitor C6 attenuate the normal mode component of noise.

  FIG. 18 shows a waveform of the voltage Vds when the switching element Q1 is turned off in the conventional example of FIG. A voltage surge having a frequency of approximately 7 MHz is generated. In the voltage surge of the voltage Vds, at the point P where the voltage is high, the diode D1 is turned on, and the vibration is clamped by the capacitor C1. Further, the amplitude of the voltage surge of the voltage Vds is gradually attenuated as the energy becomes heat and noise.

  FIG. 19 shows conduction noise characteristics in the conventional example of FIG. In the figure, part A shows noise having a peak at a frequency of 8 MHz. Part A is generated as a conduction noise due to the voltage surge of the voltage Vds in FIG. The reason why the frequency is shifted between FIG. 19 and FIG. 18 is due to the influence of the parasitic capacitance of the probe at the time of waveform measurement.

  Further, the CR snubber circuit including the capacitor C2 and the resistor R2 suppresses a voltage surge generated in the diode D2.

  Further, there is a conventional switching power supply device in which a transformer for removing a common mode signal is provided in a transformer (see, for example, Patent Document 1 related to the proposal of the present applicant).

Japanese Utility Model Publication No. 63-30230

  The purpose of such a conventional example is to realize an insulated DC power supply circuit that is less affected by a common mode signal by using a winding of a transformer. The suppression of surge generated in a switching element is caused or triggered. Not what you get. Further, the winding is not added to the filter inductor.

  On the other hand, FIG. 20A and FIG. 20B are configuration diagrams of a conventional microstrip line and show a distributed constant structure.

  FIG. 20A shows a perspective view. The distributed constant line Z1 branches from the point S from the port input which is the main line to the port output. The end of the distributed constant line Z1 is open and is an open stub.

  When the line length L of the distributed constant line Z1 is 1/4 · λ (λ is a wavelength), the distributed constant line Z1 acts as a filter of the wavelength λ and separates a specific frequency component of the signal propagating through the main line. To do.

  FIG. 20B shows a cross-sectional view. The distributed constant line Z1 is formed of a conductor on a flat plate having a width W and a thickness t. The stable potential surface Z2 is connected to the stable potential GND, is formed of a conductor on a flat plate that is sufficiently wider than the distributed constant line Z1, and is disposed in parallel to the distributed constant line Z1. The dielectric Z3 has a thickness h and a relative dielectric constant εr, and is formed so as to be disposed between the distributed constant line Z1 and the stable potential surface Z2.

  Therefore, in the conventional distributed constant structure, the distributed constant line Z1 is formed as a linear flat conductor on a plane. The stable potential surface Z2 is formed as a flat conductor.

Next, the distributed constant line Z1 will be described in detail. There is approximately the following relationship between the frequency f and the wavelength λ.
λ = C / f / Sqrt (εr)
Here, C is the speed of light (3 * 108 m / s), and εr is the dielectric constant of the dielectric Z3 (4.21 in the case of polyurethane). The wavelength in the dielectric Z3 is proportional to the reciprocal of the square root of the relative dielectric constant εr. That is, it is shortened to 1 / Sqrt (εr) as compared with the wavelength in vacuum.

  For example, when f = 7 MHz and εr = 4.21, λ = 20.9 m and 1/4 · λ = 5.22 m. The characteristics of the distributed constant line Z1 are substantially determined by the line length L, and the influence of the width W, the thickness t, the thickness h of the dielectric Z3, etc. is small.

  However, such a switching power supply device has a problem of an increase in loss due to the resistor R1 and a problem of deterioration of conduction noise characteristics.

Further, when a conventional distributed constant structure is applied at a wavelength corresponding to a frequency band (MHz band) which is a problem in the switching power supply device, there is a problem that the shape becomes large.
Specifically, if the 5.22 m distributed constant line Z1 is formed linearly, the switching power supply device becomes large and is not practical.

  An object of the present invention is to solve the above-described problems, and to provide a switching power supply device that can suppress a surge generated in a switching element with low loss and a switching power supply device that has good conduction noise characteristics. .

  Another object of the present invention is to provide a distributed constant structure capable of reducing the shape at a wavelength corresponding to a low frequency band.

The present invention which achieves such an object is as follows.
(1) In a distributed constant structure of a distributed constant line that branches off from a main line and separates a specific frequency component of a signal propagating through the main line, the distributed constant line is formed in a wound structure or a folded structure, and is switched (the n 1 or more integer) n / 4 at a wavelength specific to a voltage surge generated in the switching elements of the power supply have a line length corresponding to MHz band of about one end of the transformer winding of the switching power supply device A distributed constant structure characterized by being a distributed constant snubber circuit connected to the .
(2) In a distributed constant structure of a distributed constant line that branches from the main line and separates a specific frequency component of a signal propagating through the main line, the distributed constant line, a stable potential line connected to a stable potential point, together but are disposed adjacent to each other, the distributed constant lines and the stable potential line is formed on the wound structure or folded structure, the distributed constant line is a wavelength specific to a voltage surge generated in the switching element of the switching power supply device (the n 1 or more integer) n / 4 have a line length corresponding to the MHz band of about at, the distributed constant line is connected to one end of the transformer winding of the switching power supply device, the stable potential line is A distributed constant structure comprising a distributed constant snubber circuit connected to the other end of the transformer winding .
(3) The distributed constant structure according to (1) or (2), wherein a plurality of the distributed constant lines are arranged in parallel.
(4) the distributed constant line is a distributed constant structure according to any one of the characterized in that it is a composite magnetic element formed is wound around the transformer (1) or (2).
(5) In a distributed constant structure of a distributed constant line that branches off from a main line and separates a specific frequency component of a signal propagating through the main line, the distributed constant line is formed in a wound structure or a folded structure, and is switched It has a line length corresponding to the MHz band of about n / 4 (n is an integer of 1 or more) at a wavelength specific to the voltage surge generated in the switching element of the power supply device, and is connected to one end of the smoothing choke of the switching power supply device distributed constant structure you being a distributed constant snubber circuits.
(6) In a distributed constant structure of a distributed constant line that branches off from the main line and separates a specific frequency component of a signal propagating through the main line, the distributed constant line changes the voltage and current by turning on and off the switching element. , Which is used in a switching power supply device that converts an input voltage to an output voltage, is connected to one end of a filter inductor in the switching power supply device, and is n / 4 (n is an integer of 1 or more) at a wavelength specific to the potential point of this one end ) has a line length of about distributed constant structure according you being a composite magnetic element formed by being wound around the filter inductor.

As is apparent from the above description, the present invention has the following effects.
According to the present invention, it is possible to suppress potential fluctuations in the switching power supply device. Voltage surge and noise can be suppressed.

  In addition, according to the present invention, radiation of electromagnetic waves from the distributed constant line can be shielded. Therefore, the noise characteristics of the switching power supply device can be improved.

  Furthermore, according to the present invention, the line length of the distributed constant line can be minimized. Therefore, the switching power supply device can be made small and low in cost.

  Further, according to the present invention, the other end of the distributed constant line can be stabilized, and the shielding effect can be promoted. Therefore, the noise characteristics of the switching power supply device can be improved.

  Furthermore, according to the present invention, the switching power supply device can suppress an increase in the number of parts, and can be small and low cost. It can be formed in a practical size.

  In addition, according to the present invention, a distributed constant structure capable of forming an element in a small size is provided. The mounting area can be reduced. A switching power supply can be formed in a practical size.

  Furthermore, according to the present invention, it is possible to suppress potential fluctuations and noise in a wide band by a plurality of distributed constant lines. Further, noise can be suppressed in the switching power supply.

  According to the present invention, a plurality of voltage surges can be suppressed with a single element in a switching power supply. In addition, common mode noise can be suppressed in the switching power supply.

  Hereinafter, the present invention will be described in detail with reference to FIG. FIG. 1 is a block diagram showing an embodiment of a switching power supply device according to the present invention. In addition, the same code | symbol is attached | subjected to the same element as the prior art example of FIG. 17, and description is abbreviate | omitted.

1 is that a distributed constant snubber circuit 20 composed of a distributed constant line Z1, a stable potential surface Z2, and a dielectric Z3 is provided as a primary side snubber circuit.
In the distributed constant snubber circuit 20, the distributed constant line Z1, the stable potential surface Z2, and the dielectric Z3 constitute a distributed constant filter circuit.

  The distributed constant snubber circuit 20 forms a filter by a distributed constant line Z1 that branches at the voltage Vds in the path from the primary winding N1 of the transformer T1 that is the main line to the drain of the switching element Q1, and is formed by an open stub. Is done.

  The distributed constant line Z1 has one end connected to the voltage Vds, which is a fluctuating potential point in the switching power supply device, and the other end opened. Further, it has a line length of ¼ wavelength corresponding to the frequency 7 MHz of the voltage surge specific to the voltage Vds.

  The stable potential surface Z2 is disposed adjacent to the distributed constant line Z1, and is connected to the voltage Vb which is a stable potential. The dielectric Z3 is provided between the distributed constant line Z1 and the stable potential surface Z2.

  FIG. 2 is a block diagram showing an embodiment of the distributed constant snubber circuit 20, showing a distributed constant structure. The distributed constant line Z1 is formed on the film 21 in a zigzag of a folded structure, and a dielectric Z3 formed in a foil shape is disposed adjacent to the film 21, and the equipotential surface formed in a foil shape adjacent to the film 21 is stabilized. The potential surface Z2 is disposed, and further, the insulating film 22 is disposed, and these are formed to be wound and folded like a film capacitor.

  One end of the distributed constant line Z1 is connected to the lead line 23, and the lead line 23 is connected to a voltage Vds which is a potential point that fluctuates in the switching power supply device. The other end of the distributed constant line Z1 is opened.

  The lead line 23 is a part of the distributed constant line Z1, and the line length of the lead line 23 is a part of the line length of the distributed constant line Z1.

  Similarly, the stable potential surface Z2 is connected to the lead line 24, and the lead line 24 is connected to the voltage Vb which is a stable potential in the switching power supply device.

  FIG. 3 is a block diagram showing another embodiment of the distributed constant snubber circuit 20, showing a distributed constant structure. 3 is characterized in that the distributed constant snubber circuit 20 is composed of multilayer printed coils.

  The distributed constant line Z1 is formed on the spiral of the winding structure on the wiring layer 26, the dielectric Z3 is disposed adjacently, and the wiring layer 27 in which the stable potential surface Z2 is disposed adjacently is disposed. Are superposed like a multilayer printed coil.

  One end of the distributed constant line Z1 is connected to the connection hole 28. Further, the connection hole 28 is connected to the means 29 for connecting the connection holes, and the means 29 for connecting the connection holes is also a connection hole of the circuit board 25 of the switching power supply device. Connect to P11 and connect to voltage Vds, which is a changing potential point in the switching power supply. The other end of the distributed constant line Z1 is opened.

  The connection hole 28, the means 29 for connecting the connection holes, and the connection hole P11 are a part of the distributed constant line Z1, and the line length thereof is a part of the line length of the distributed constant line Z1.

  Similarly, the stable potential surface Z2 is connected to the connection hole P23 of the circuit board 25 of the switching power supply device via the connection hole and the means for connecting the connection holes, and is connected to the voltage Vb which is a stable potential in the switching power supply device. To do.

  Next, the line length of the distributed constant line Z1 will be described. As in the conventional example of FIG. 20, when f = 7 MHz and εr = 4.21, λ = 20.9 m and ¼ · λ = 5.22 m.

  FIG. 4 shows an image of the voltage amplitude characteristic of the open stub in the distributed constant snubber circuit 20. In the path from the primary winding N1 of the transformer T1, which is the main line, to the drain of the switching element Q1, it branches at the voltage Vds. The voltage Vds at the branch point of the open stub is a connection point between the primary winding N1 of the transformer T1, the drain end of the switching element Q1, and the distributed constant line Z1. In the configuration diagram of FIG. 2, the distributed constant line Z1 is shown to be linearly arranged on a plane, but in actuality, it is formed as a distributed constant structure of a wound structure or a folded structure.

  At a frequency where the line length L of the distributed constant line Z1 is 1/4 · λ, the amplitude is maximum at the open end, the amplitude is zero at the branch end, and the branch end functions as a filter. Similarly, it acts as a filter at frequencies of 3/4 · λ and 5/4 · λ, and a specific frequency component of a signal propagating in the path from the primary winding N1 of the transformer T1 to the drain of the switching element Q1 is obtained. To separate.

  Similarly, the voltage amplitude characteristic (not shown) of the short stub formed by the short-circuited end has the maximum amplitude at the center of the distributed constant line Z1 at a frequency where the line length of the distributed constant line Z1 is 1/2 · λ. The amplitude becomes zero at the branch end and the short-circuit end, and the branch end functions as a filter.

  FIG. 5 shows the impedance characteristics of the distributed constant snubber circuit 20. At a frequency of approximately 7 MHz at the point P, the amplitude (Gain) becomes the lowest and the phase (Phase) is inverted.

  As can be seen from this, in the frequency band (MHz band) and the low frequency band which are problems in the switching power supply device, the characteristics of the distributed constant line Z1 are almost determined by the line length L, the width W and The influence of the thickness etc. is small. In addition, the influence of whether the arrangement is linear or coiled or whether it is wound and folded is small.

  Therefore, according to the distributed constant structure in which the distributed constant line Z1 is formed in a wound structure or a folded structure at a wavelength corresponding to a low frequency band, the size can be reduced.

  The operation of the embodiment of FIG. 1 will be described. The description of the conventional example in FIG. 17 is omitted. The distributed constant snubber circuit 20 suppresses a voltage surge that occurs when the switching element Q1 is turned off.

  Specifically, when the switching element Q1 is on, the voltage Vds is low. Next, when the switching element Q1 is turned off, the voltage Vds rises and a voltage surge is generated. The component of the voltage surge having a frequency of 7 MHz becomes low impedance and is suppressed by the voltage Vds at the branch end of the distributed constant line Z1. On the other hand, the component of the voltage surge having a frequency of 7 MHz is emitted as an electromagnetic wave at the open end of the distributed constant line Z1, but is shielded by the stable potential plane Z2.

  FIG. 6 shows a waveform of the voltage Vds when the switching element Q1 is turned off in the embodiment of FIG. The component of the voltage surge having a frequency of 7 MHz disappears and a component of approximately 3 MHz is generated. This suppresses the voltage surge peak of the voltage Vds. Further, the distributed constant snubber circuit 20 generates almost no loss.

  FIG. 7 shows the conduction noise characteristics in the embodiment of FIG. Compared with the conventional example of FIG. 19, noise having a peak at a frequency of 8 MHz in the A portion is reduced. This is because the distributed constant snubber circuit 20 suppresses the 7 MHz component of the voltage surge of the voltage Vds.

In this way, the distributed constant snubber circuit 20 suppresses a voltage surge generated when the switching element Q1 is turned off with low loss.
The distributed constant snubber circuit 20 can be formed in a practical size.

  FIG. 8 is a block diagram of a second embodiment of the switching power supply device according to the present invention. Note that the same elements as those in the embodiment of FIG.

8 is characterized in that a transformer and a primary snubber circuit are combined with a distributed constant line Z1, a stable potential surface Z2, a dielectric Z3, a primary winding N1, and a secondary winding N2. It is in the point which consists of 30.
Specifically, in the composite magnetic element 30, the primary winding N1, the secondary winding N2, the distributed constant line Z1, and the stable potential surface Z2 are formed by being wound around the same core.

  FIG. 9 shows a sectional view of the winding structure in the composite magnetic element 30 of the embodiment of FIG. In the drawing, the lower side shows the center side of the composite magnetic element 30, and the upper side shows the outside of the composite magnetic element 30. Each winding and stable potential surface constitutes a layer. From the center side, the secondary winding N2, the primary winding N1, the stable potential surface Z2a, the distributed constant line Z1, and the stable potential surface Z2b are used. Each layer is disposed on the bobbin B, and the core C is disposed outside the bobbin B.

  The distributed constant line Z1 has one end connected to the voltage Vds, which is a fluctuating potential point in the switching power supply device, and the other end opened. Further, it has a line length of ¼ wavelength corresponding to the frequency 7 MHz of the voltage surge specific to the voltage Vds.

  The stable potential surface Z2 includes a stable potential surface Z2a and a stable potential surface Z2b, is disposed adjacent to the distributed constant line Z1, and is connected to a voltage Vb that is a stable potential. The stable potential surface Z2a and the stable potential surface Z2b are formed in a foil shape, and are formed as one Faraday shield so that both ends do not short-circuit.

  The distributed constant line Z1 is covered with polyurethane of the dielectric Z3 and arranged in close contact with the stable potential surface Z2. The stable potential surface Z2a and the stable potential surface Z2b are arranged with a distributed constant line Z1 interposed therebetween, and have a distributed constant structure formed in a coil shape of a wound structure. This structure promotes the effectiveness of the shield.

  FIG. 10 shows a cross-sectional view of another winding structure in the composite magnetic element 30 of the embodiment of FIG. Compared to the cross-sectional view of FIG. 9, the cross-sectional view of FIG. 10 is characterized in that the stable potential line Z2c is disposed adjacent to the distributed constant line Z1 instead of the stable potential surface Z2, and the distributed constant line Z1 and the stable potential are The line Z2c is formed by winding it in a coil shape having a winding structure. Description of the same parts as those in the cross-sectional view of FIG. 9 is omitted.

  Specifically, the layers of the respective windings and stable potential lines are the secondary winding N2, the primary winding N1, the distributed constant line Z1, and the stable potential line Z2c from the center side.

  The distributed constant line Z1 and the stable potential line Z2c are bifara windings, arranged in parallel, adjacent to the same line length, and distributed to form the distributed constant line Z1 and the stable potential line Z2c in a winding structure. A constant structure.

  The voltage Vds connection end of the distributed constant line Z1 and the open end of the stable potential line Z2c are matched, and the open end of the distributed constant line Z1 and the connection end of the voltage Vb that is the stable potential of the stable potential line Z2c are matched.

  When the distributed constant line Z1 and the stable potential line Z2c are bi-directional, the distributed constant line Z1 and the stable potential line Z2c are coupled to each other and cancel the voltage induced by the magnetic flux of the core C, which is suitable for surge suppression. Characteristics.

  The operation of the embodiment of FIG. 8 is the same as that of the embodiment of FIG. The embodiment of FIG. 8 has a reduced number of elements, is smaller, and is less expensive than the embodiment of FIG.

  In the above example, the distributed constant line Z1 and the stable potential line Z2c are arranged in a bi-directional manner, but separately from this, the distributed constant line Z1 and the stable potential line Z2c are formed by a coaxial cable, and this is formed into a winding structure. A distributed constant structure may be formed. Specifically, in the distributed constant line Z1 and the stable potential line Z2c, one is the inner conductor of the coaxial cable and the other is the outer conductor of the coaxial cable.

  FIG. 11 is a block diagram of a third embodiment of the switching power supply device according to the present invention. In addition, the same code | symbol is attached | subjected to the same element as the Example of FIG. 8, and description is abbreviate | omitted.

  11 is characterized in that a transformer, a primary-side snubber circuit, and a secondary-side snubber circuit include a distributed constant line Z1, a stable potential surface Z2, a dielectric Z3, a primary winding N1, a secondary winding N2, The composite magnetic element 40 is composed of the distributed constant line Z4, the stable potential surface Z5, and the dielectric Z6.

  The distributed constant line Z4, the stable potential surface Z5, and the dielectric Z6 constitute a distributed constant snubber circuit similarly to the distributed constant line Z1, the stable potential surface Z2, and the dielectric Z3, and suppress the voltage surge generated in the diode D2.

  The distributed constant line Z4 has one end connected to the anode of the diode D2, which is a variable potential point in the switching power supply device, and the other end is open. Moreover, it has a line length of ¼ wavelength with respect to a voltage surge inherent to the anode of the diode D2.

  The stable potential surface Z5 is disposed adjacent to the distributed constant line Z4 and is connected to the stable potential GND. The dielectric Z3 is provided between the distributed constant line Z1 and the stable potential surface Z2.

  Since the operations of the distributed constant line Z4, the stable potential plane Z5, and the dielectric Z6 are the same as those of the distributed constant snubber circuit 20 in the embodiment of FIG.

  FIG. 12 shows a cross-sectional view of the winding structure in the composite magnetic element 40 of the embodiment of FIG. The cross-sectional view of FIG. 12 is characterized in that a winding and a stable potential surface are arranged outside the core C and wound.

  Also in the embodiment of FIG. 11, the windings and the stable potential surface may all be arranged inside the core C as shown in the cross-sectional views of FIGS. 9 and 10. Similarly, in the embodiment of FIG. 8, the winding and the stable potential surface may be arranged outside the core C as shown in the sectional view of FIG. Similar effects can be obtained.

  In the cross-sectional view of FIG. 12, the lower side shows the center side of the composite magnetic element 40, and the upper side shows the outside of the composite magnetic element 40. Each winding and stable potential surface constitutes a layer. The secondary winding N2 and the primary winding N1 are arranged on the bobbin Ba on the center side of the core C, and the distributed constant line Z1, the stable potential plane Z2, the distributed constant line Z4, and the stable potential plane Z6 are bobbins outside the core C. A distributed constant structure is formed by arranging them in Bb and forming them in a wound structure.

  The stable potential surface Z2 and the stable potential surface Z5 are formed in a foil shape, and are short-circuited at both ends as a short ring. Therefore, they are equipotential surfaces, and the potential is stable. Further, the magnetic flux generated by the primary winding N1 and the secondary winding N2 does not interlink with the distributed constant line Z1, the stable potential plane Z2, the distributed constant line Z4, and the stable potential plane Z5. It becomes a characteristic suitable for suppression.

  FIG. 13 is a perspective view of the appearance of the composite magnetic element 40 of FIG. The bobbin Bb is disposed outside the core C.

  The operation of the embodiment of FIG. 11 is the same as that of the embodiment of FIG. Compared with the embodiment of FIG. 8, the embodiment of FIG. 11 has a reduced number of elements, a small size and a low cost, and a low loss.

  In the above example, the distributed constant line Z1, the stable potential surface Z2 and the dielectric Z3, and the distributed constant line Z4, the stable potential surface Z5, and the dielectric Z6 constitute an open stub. You may make it comprise a short stub.

  Specifically, the distributed constant line Z1 has one end connected to a voltage Vds that is a fluctuating potential point in the switching power supply device, and the other end connected to a voltage Vb that is a stable potential, and a voltage surge inherent to the voltage Vds. The line length is about ½ wavelength. The distributed constant line Z4 has one end connected to the anode of the diode D2, which is a variable potential point in the switching power supply, and the other end connected to the stable potential GND. / The line length is about 2 wavelengths.

  Since the operation in such a case is the same as that of the above-described embodiment, the description thereof will be omitted. However, in the case of a short stub, the ends of the distributed constant line Z1 and the distributed constant line Z4 become stable potentials, and the amplitude is maximum. Since it becomes the center of stable potential surface Z2 and stable potential surface Z5, the effect of a shield can be accelerated | stimulated.

  In the above example, the flyback converter is used. However, a forward converter, a non-insulated converter, or other converter system may be used. Even in this case, the same effect can be obtained.

  Furthermore, in the above-described example, the snubber circuit and the transformer are combined as a composite magnetic element. Alternatively, the snubber circuit and the smoothing choke may be combined as a composite magnetic element. Even in this case, the size can be reduced similarly.

  FIG. 14 is a block diagram of a fourth embodiment of the switching power supply according to the present invention. In addition, the same code | symbol is attached | subjected to the same element as the prior art example of FIG. 17, and description is abbreviate | omitted.

  The embodiment of FIG. 14 is characterized in that the line filter T2 which is the filter inductor of FIG. 17 includes the distributed constant lines Z7 to Z11, the stable potential surface Z12, the dielectric Z13, the distributed constant lines Z14 to Z18, the stable potential surface Z19, and the dielectric. The composite magnetic element 50 is formed by winding Z20.

  The composite magnetic element 50 acts as a filter that suppresses noise on the line. The distributed constant line not only suppresses a surge as in the embodiments of FIGS. 1, 8, and 11, but can also suppress noise in the embodiment of FIG.

  Specifically, the distributed constant lines Z7 to Z11, the stable potential surface Z12 and the dielectric Z13, and the distributed constant lines Z14 to Z18, the stable potential surface Z19 and the dielectric Z20 are arranged symmetrically.

  The distributed constant lines Z7 to Z11 and the distributed constant lines Z14 to Z18 have one end connected to the connection points Vc and Vd between the line filter and the diode bridge D3, which are potential points in the switching power supply device, and the other ends are open. To do.

  In the path from the line filter that is the main line to the diode bridge D3, the distributed constant lines Z7 to Z11 and the distributed constant lines Z14 to Z18 that branch at the connection points Vc and Vd constitute a filter, and the signal that propagates through the main line is specified. Are separated.

  The distributed constant lines Z7 to Z11 and the distributed constant lines Z14 to Z18 connect five distributed constant lines in parallel, respectively. The line lengths of the five distributed constant lines are 15 m, 1.5 m, 1 m, 0.75 m, and 0.5 m, respectively.

  The stable potential planes Z12 and Z19 are arranged adjacent to the distributed constant lines Z7 to Z11 and the distributed constant lines Z14 to Z18, and are connected to the stable potential GND. The dielectrics Z13 and Z20 are provided between the distributed constant lines Z7 to Z11 and the distributed constant lines Z14 to Z18, and the stable potential planes Z12 and Z19.

  Specifically, the distributed constant lines Z7 to Z11 and the distributed constant lines Z14 to Z18 are covered with polyurethane of dielectrics Z13 and Z20, are in close contact with the stable potential surfaces Z12 and Z19, and are wound around the core of the line filter T2. A constant structure.

  By connecting the distributed constant lines in parallel, the filter characteristics work in a wide band. The line lengths of the distributed constant lines are 15 m, 1.5 m, 1 m, 0.75 m, and 0.5 m, and εr = 4.21, and frequencies 2.4 MHz, 24 MHz, 37 MHz, 49 MHz, and 73 MHz correspond.

  FIG. 15 shows attenuation characteristics of the line filter T2 and the composite magnetic element 50. FIG. A characteristic Ca indicates the characteristic of the conventional line filter T2 of FIG. A characteristic Cb shows the characteristic of the composite magnetic element 50 in the embodiment of FIG.

  The characteristic Ca of the line filter T2 has a resonance point at about 500 kHz, and the maximum attenuation value is obtained near this resonance point. At a frequency higher than the resonance point, the attenuation value rises and the filter characteristics decline.

  The characteristic Cb of the composite magnetic element 50 is equivalent to the characteristic Ca at a frequency lower than the resonance point 500 kHz, but the effect of the distributed constant lines Z7 to Z11 and the distributed constant lines Z14 to Z18 at a frequency higher than the resonance point. As a result, an increase in the attenuation value is suppressed, and the characteristics of the filter are promoted.

  In the characteristic Cb, peak characteristics Pa and Pb can be observed at the inherent frequencies 2.4 MHz and 24 MHz of the distributed constant line.

  FIG. 16 shows the conduction noise characteristics of the embodiment of FIG. Compared to the conventional example of FIG. 19, the noise level is reduced at a frequency higher than the resonance point of 500 kHz. The composite magnetic element 50 suppresses noise.

  In the above example, distributed constant lines are arranged on both lines of the line filter, which is a filter inductor, to suppress common mode noise. Separately, a normal mode choke (FIG. An effect can be obtained even if a distributed constant line is arranged in (not shown) to suppress normal mode noise.

It is a block diagram which shows one Example of this invention. 2 is a configuration diagram illustrating an example of a distributed constant snubber circuit 20. FIG. FIG. 6 is a configuration diagram showing another embodiment of the distributed constant snubber circuit 20. It is an image of the voltage amplitude characteristic of an open stub. It is an impedance characteristic of the distributed constant snubber circuit 20. It is the voltage Vds waveform of the Example of FIG. It is the conduction noise characteristic of the Example of FIG. It is a block diagram which shows the 2nd Example of this invention. 3 is a cross-sectional view of a winding structure in the composite magnetic element 30. FIG. 4 is a cross-sectional view of another winding structure in the composite magnetic element 30. FIG. It is a block diagram which shows the 3rd Example of this invention. 3 is a cross-sectional view of a winding structure in the composite magnetic element 40. FIG. 2 is a perspective view of an appearance of a composite magnetic element 40. FIG. It is a block diagram which shows the 4th Example of this invention. This is an attenuation characteristic of the line filter T2 and the composite magnetic element 50. It is the conduction noise characteristic of the Example of FIG. It is a block diagram of the conventional switching power supply device. It is the voltage Vds waveform of the prior art example of FIG. It is the conduction noise characteristic of the prior art example of FIG. It is a block diagram of the conventional microstrip line. (A) is a perspective view, (b) is a sectional view.

Explanation of symbols

20 Distributed constant snubber circuits 30, 40, 50 Composite magnetic elements Z1, Z4, Z7 to Z11, Z14 to Z18 Distributed constant lines Z2, Z2a, Z2b, Z5, Z12, Z19 Stable potential plane Z2c Stable potential lines Z3, Z6, Z13 , Z20 Dielectric T1 Transformer T2 Line filter COM, GND, Vb Stable potential

Claims (6)

In the distributed constant structure of the distributed constant line that branches off from the main line and separates a specific frequency component of the signal propagating through the main line,
The distributed constant line is
Formed into a wound or folded structure,
N / 4 at a wavelength specific to a voltage surge generated in the switching element of the switching power supply device (n is an integer of 1 or more) have a line length corresponding to MHz band of about,
A distributed constant structure characterized by a distributed constant snubber circuit connected to one end of a transformer winding of the switching power supply device . In the distributed constant structure of the distributed constant line that branches off from the main line and separates a specific frequency component of the signal propagating through the main line,
The distributed constant line and the stable potential line connected to the stable potential point are disposed adjacent to each other,
The distributed constant line and the stable potential line is formed on the wound structure or folded structure,
The distributed constant line can have a line length corresponding to MHz band of about (1 or more integer n) n / 4 at a wavelength specific to a voltage surge generated in the switching element of the switching power supply device,
The distributed constant line is connected to one end of a transformer winding of the switching power supply device,
A distributed constant structure, wherein the stable potential line is a distributed constant snubber circuit connected to the other end of the winding of the transformer . The distributed constant structure according to claim 1, wherein a plurality of the distributed constant lines are arranged in parallel. The distributed constant line is a distributed constant structure according to claim 1 or claim 2, wherein said <br/> be a composite magnetic element formed is wound around the transformer. In the distributed constant structure of the distributed constant line that branches off from the main line and separates a specific frequency component of the signal propagating through the main line,
The distributed constant line is
Formed into a wound or folded structure,
A line length corresponding to a MHz band of about n / 4 (n is an integer of 1 or more) at a wavelength specific to a voltage surge generated in the switching element of the switching power supply device;
Distributed constant structure you wherein a distributed constant snubber circuit connected to one end of the smoothing choke of the switching power supply <br/>. In the distributed constant structure of the distributed constant line that branches off from the main line and separates a specific frequency component of the signal propagating through the main line,
The distributed constant line is
It is used in switching power supply devices that change the voltage and current by turning on and off the switching element and convert the input voltage to the output voltage.
Connected to one end of a filter inductor in the switching power supply,
It has a line length of about n / 4 (n is an integer of 1 or more) at a wavelength inherent to the potential point at one end,
Distributed constant structure according you, characterized in that <br/> a composite magnetic element formed by being wound around the filter inductor.

Images