JPH11356047A - Switching regulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise terminal voltage and leakage current of high frequencies, simplify the mechanism of a radiator, and eliminate restrictions in specification on an insulation distance and a space interval between a frame ground terminal and the radiator. SOLUTION: A switching element 5 of an inverter 1 for suppressing higher harmonic waves and a switching element 6 of an insulation type DC-DC inverter 2 are installed in one and the same radiator 8 for ambient air cooling located on a printed wiring board 9. This radiator 8 is connected to the stable potential at the primary side of the insulation type DC-DC converter 2 including the inverter 1 for suppressing higher harmonic waves, such as the plus or the minus side of an input electrolytic capacitor C1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching regulator power supply in which a harmonic suppression inverter for suppressing harmonics and an insulation type DC / DC converter for insulating a primary side and a secondary side are cascaded. About.

[0002]

2. Description of the Related Art Conventionally, a switching regulator power supply, which is known as a power supply having high conversion efficiency, uses a rectifying method of a capacitor input type, so that it contains many harmonic components and generates a waveform of an AC line. This may cause distortion or harmonic interference that may cause other devices to malfunction.

[0003] In order to prevent such harmonic interference, conventionally, as shown in FIG. 4 (A), a harmonic suppression inverter 1 known as an active filter is used to insulate a primary side from a secondary side. It is connected before the isolated DC / DC converter 2 for conversion. FIG. 4A shows only the main circuit of each inverter.

[0004] The harmonic suppression inverter 1 is provided with a step-up chopper comprising an inductance L1, a switching element 5, a diode D1, and an input smoothing capacitor C1, following a rectifying diode bridge 4. The switching element 5 of the step-up chopper stabilizes the output voltage by PWM control based on fixed oscillation of a control unit (not shown), and changes the peak value of the input current flowing by switching into a sine waveform to match the sine waveform of the input voltage. To improve power factor and suppress harmonics.

The isolated DC / DC converter 2 is an example of a forward converter, in which a switching element 6 is connected to a primary winding 7a of a transformer 7, and diodes D2 and D3 for rectification and a choke coil are connected to a secondary winding 7b. L2 and the capacitor C2 are connected. Switching element 6
Turns on and off so as to stabilize the output voltage by PWM control based on fixed oscillation of a control unit (not shown).

That is, by the on / off operation of the switching element 6, a rectangular wave voltage having an on-time width is applied to the secondary low-frequency filter composed of the choke coil L2 and the capacitor C2. , The average voltage becomes the output voltage. In the choke coil L2, a current in a form in which a small triangular alternating current is superimposed on a large direct current flows.

Further, the harmonic suppression inverter 1 and the insulation type D
In the switching regulator power supply device in which the C / DC converters 2 are cascaded, the negative line of the primary circuit separated by the transformer 7 is connected to the frame ground (FG) of the frame ground terminal 10 via the capacitor C3. The negative line of the side circuit is connected to the frame ground (FG) of the frame ground terminal 10 via the capacitor C4.

FIG. 4B shows a heat radiation structure of the switching elements 5 and 6 provided in each inverter of FIG. 4A. A heat radiator 8 for natural air cooling is mounted on a printed wiring board 9 and switching is performed. Elements 5 and 6 are attached. The radiator 8
As shown in FIG. 4A, it is connected to the frame ground (FG) of the frame ground terminal 10.

[0009]

However, such a conventional inverter for suppressing harmonics and an isolated DC / DC
The switching regulator power supply device in which the converters are cascaded has a structure in which the heat of the switching elements 5 and 6 is radiated by connecting the frame radiator 8 to the frame ground terminal FG by connecting the converter to the frame ground terminal 10. The insulation distance and the space distance between the radiator 8 of the switching element 5 and the radiator 8 of the switching element 6 must be separated and arranged so as to secure the specified distance between the primary and the FG determined by the standard.

Therefore, the radiator 8 on the printed wiring board 9
There is a problem that the installation space of the device is widened and the arrangement of other elements is restricted. Switching elements 5 and 6 and radiator 8
, A common current flows through the radiator 8 which is the frame ground FG due to the high-voltage / high-frequency inverter voltage waveform, and the noise terminal voltage increases and the high-frequency leakage current increases. There was a problem that.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and reduces a noise terminal voltage and a high-frequency leakage current, simplifies a radiator mechanism, and further provides insulation between a frame ground and a radiator. An object of the present invention is to provide a switching regulator power supply device that is not subject to restrictions on standards for distance and space distance.

[0012]

In order to achieve this object, the present invention is configured as follows. First, the present invention includes a harmonic suppression inverter for suppressing harmonics, and an isolated DC / DC converter cascade-connected to the harmonic suppression inverter for insulating the primary side and the secondary side. Switching regulator power supply device.

The present invention is directed to such a switching regulator power supply device, in which a switching element of a harmonic suppression inverter and a switching element of an isolated DC / DC inverter are each disposed on a printed wiring board as a single radiator for natural air cooling. And the radiator is connected to a stable potential on the primary side of an insulated DC / DC converter including a harmonic suppression inverter.

In order to connect the radiator to the stable potential on the primary side of the harmonic suppression inverter, the radiator is directly connected to the plus side or the minus side of the input electrolytic capacitor provided in the harmonic suppression inverter. Further, the radiator may be connected to a positive side or a negative side of an input electrolytic capacitor provided in the harmonic suppression inverter via a capacitor.

As described above, since the radiator is not connected to the ground frame, the distance between the radiator and the switching element can be arbitrarily selected without being restricted by the standard. In addition, due to the presence of stray capacitance between the switching element and the radiator, even if a high-frequency current flows from the switching element to the radiator due to the high-voltage / high-frequency inverter voltage waveform, it is connected to the primary-side stable potential. Therefore, the high-frequency current does not flow to the frame ground, and the noise terminal voltage and the high-frequency leakage current can be prevented from increasing.

[0016]

FIG. 1 is a circuit diagram and a radiator structure of a first embodiment of the present invention. FIG. 1A shows a first embodiment of the present invention.
In the circuit of the embodiment, a harmonic suppression inverter 1 functioning as an active filter and an insulation type DC / DC inverter 2 for insulating a primary side and a secondary side are cascaded. The harmonic suppression inverter 1 receives an AC input to the input terminals 3a and 3b, and supplies a rectified output of the rectifying diode bridge 4 to the boost chopper.

The boost chopper comprises a switching element 5 using a MOSFET, an inductance L1, a rectifying diode D1, and an input smoothing capacitor C1.
The switching element 5 is turned on and off by PWM control obtained by fixed oscillation of a control unit (not shown) to stabilize the output voltage, and at the same time, adjusts the amplitude of the switching current to the sine waveform of the AC voltage, and enhances the harmonics by improving the power factor. We aim at wave suppression.

The isolated DC / DC inverter 2 is an example of a forward converter. The output voltage of a switching element 6 using a MOSFET connected in series to a primary winding 7a of a transformer 7 is stabilized by a control unit (not shown). As described above, the power supply is turned on and off by the PWM control, and a specified DC output voltage is generated at the output terminals 11a and 11b by the rectifying diodes D2 and D3 of the secondary winding 7b, the choke coil L2 and the smoothing capacitor C2.

The switching element 5 provided in the harmonic suppression inverter 1 and the switching element 6 provided in the insulated DC / DC inverter 2 are connected to a printed wiring board 9 like the radiator structure shown in FIG. It is mounted side by side on a single natural air cooling radiator 8 fixed above. This radiator 8
As is clear from the circuit diagram of FIG. 1 (A), the stabilization potential on the primary side of the isolated DC / DC inverter 2 including the harmonic suppression inverter 1, that is, the primary side of the transformer 7 is
For example, it is directly connected to the negative side of the input electrolytic capacitor C1.

The line from the frame ground terminal (FG terminal) 10 is connected to the negative line on the primary side of the transformer 7 to which the radiator 8 is connected via the capacitor C3. It does not become the frame ground as in the conventional example. The line from the frame ground terminal 10 is connected to a negative line on the secondary side of the transformer 7 via a capacitor C4.

Since the radiator 8 is separated from the frame ground (FG) of the frame ground terminal 10 as described above, the switching between the switching elements 5 and 6 of each of the inverters 1 and 2 and the radiator 8 in FIG. The insulation distance and the space distance, that is, the restriction that the primary side-FG distance defined in the standard must be ensured, are released. As a result, without being restricted by the standard, FIG. ), On one natural air cooling radiator 8, the switching elements 5 of each inverter with an arbitrary insulation distance and space distance.
6 can be arranged.

Next, the operation of the first embodiment shown in FIG. 1 will be described. In the supply state of the AC input to the input terminals 3a and 3b, the harmonic suppression inverter 1 stabilizes the output by the PWM control of the switching element 5 by a control unit (not shown), and at the same time, improves the power factor by making the current waveform a sine waveform. Harmonic suppression is attempted.

The isolated DC / DC inverter 2 receives a DC input from the input electrolytic capacitor C1, turns on the switching element 6 by PWM control from a control unit (not shown),
Turn off to stabilize the output voltage. Switching element 6
Is turned on and off, the rectangular wave voltage obtained on the secondary side is rectified by rectifier diodes D2 and D3, and then the choke coil L
2 and the output terminal 11
a and 11b to the load.

When a high-voltage and high-frequency inverter voltage waveform is generated by the switching operation of the harmonic suppression inverter 1 and the isolated DC / DC inverter 2 as shown in FIG. , And 6, there is a stray capacitance, and a high-frequency current tends to flow to the radiator 8 through the stray capacitance.

However, as shown in FIG. 1A, the radiator 8 is input to the negative side of the input electrolytic capacitor C1 which is a stabilized potential on the primary side of the transformer 7, and
Does not flow through the line from the frame ground terminal 10 via the capacitor C3.

For this reason, the common current in the frame ground terminal 10 is reduced, the noise terminal voltage is reduced, and the high frequency leakage current is also reduced. Moreover, since the switching elements 5 and 6 used in the two inverters are fixed to one radiator 8, the printed wiring board 9 of the radiator 8
And the space for installing the radiator 8 on the printed wiring board 9 can be reduced.

FIG. 2 shows a second embodiment of the present invention, which is characterized in that a radiator is connected to a stable potential on the primary side of the inverter via a capacitor.

FIG. 2A is a circuit diagram of the second embodiment. The circuit configuration of the harmonic suppression inverter 1 and the isolated DC / DC inverter 2 is the same as that of the embodiment of FIG. The radiator structure in which two switching elements 5 and 6 are attached to the radiator 8 in FIG. 2B is also shown in FIG.
Is the same as

On the other hand, in the second embodiment shown in FIG. 2, as shown in the circuit diagram of FIG. Insulated DC / D including wave suppression inverter 1
It is connected to the primary side of the C inverter 2, that is, to the negative side of the capacitor C1, which is a stable potential on the primary side of the transformer 7.

As described above, the radiator 8 is connected to the capacitor C via the capacitor C5 to be a stable potential on the primary side of the transformer 7.
1, the radiator 8 can be separated from the line of the frame ground terminal 10 by connecting the radiator 8 to the radiator 8 as shown in FIG. 2B as in the first embodiment of FIG. There is no restriction on the insulation distance and the space distance between the radiator 8 and the ground frame 10 stipulated in the standard when the switching elements 5 and 6 are attached.

At the same time, the radiator 8 and the switching elements 5, 6
In this case, even if a high-frequency current flows through the radiator 8 due to the high-voltage / high-frequency inverter voltage waveform, the high-frequency current is cut by the capacitor C5, and the high-frequency current is cut off by the capacitor C1. The leakage current can be reduced, and as a result, the noise terminal voltage on the frame ground terminal 10 side, the common current, and the leakage current can be reduced.

Further, since the radiator 8 is separated from the primary stable potential in a DC manner by the capacitor C5, even if the capacitor C5 is connected to the plus side which is another stable potential of the capacitor C1, the radiator 8 is Since the DC does not become a positive potential, safety is improved.

FIG. 3 shows a third embodiment of the present invention, in which a large-power switching regulator power supply device is taken as an example. In the circuit diagram of FIG. 3A, input stacks 12 and 13 are provided following the input terminals 3a and 3b of the harmonic suppression inverter 1 located at the preceding stage.

The input stacks 12 and 13 have four diodes bridge-connected, the AC input terminals of the diode bridges are commonly connected to each of the input terminals 3a and 3b, and the rectified outputs of the input stacks 12 and 13 have positive and negative sides. The rectification input to the boost chopper is performed by commonly connecting the negative sides. The boost chopper provided following the input stacks 12 and 13 is the same as the embodiment of FIG. Also, the insulation type DC / DC inverter 2 is the same as the embodiment of FIG.

The radiator structure in the third embodiment shown in FIG. 3 is similar to the radiator structure mounted on the printed wiring board 9 as shown in FIG.
In addition to the switching elements 5 and 6 provided in each inverter, the input stacks 12 and 13 requiring heat radiation, and the output rectifying diode D for the boost chopper
1 is attached. In addition to this, for example, a radiator 8 may be used to start a power element or the like of a control unit (not shown) that requires heat radiation.
Attach to

The radiator 8 is an input electrolytic capacitor C which has a stable potential on the primary side of the isolated DC / DC inverter 2 including the inverter for suppressing harmonics, that is, on the primary side of the transformer 7.
1 is directly connected to the negative side. Of course, in the embodiment of FIG. 3, as in FIG. 2, the radiator 8 may be connected to the negative side of the input electrolytic capacitor C1 via the capacitor C5.

In the above embodiment, the radiator 8 is connected directly to the radiator 8 or via the capacitor C5.
Is connected to the primary side of the insulated DC / DC inverter 2, that is, the negative side of the input electrolytic capacitor C 1 which is a stabilized potential on the primary side of the transformer 7. May be connected to the plus side.

In the above-described embodiment, the case where MOSFETs are used as the switching elements 5 and 6 of the inverter is taken as an example. However, the same applies to the case where a bipolar transistor or IGBT is used.

In the above-described embodiment, the heat radiation is required.
A heat radiating structure for mounting all of the secondary semiconductor elements to the heat radiator 8 is included.

The present invention further relates to an inverter 1 for suppressing harmonics.
In this example, a step-up chopper is used and a forward inverter is used as the insulated DC / DC inverter 2. However, the present invention is not limited to these inverter types, and can be applied to any appropriate combination of inverters. .

[0041]

As described above, according to the present invention, between the harmonic suppression inverter and one radiator plate on which the switching element used for each of the isolated DC / DC inverters is mounted. All of the high-frequency current flowing due to the generated stray capacitance flows to the stable potential side on the primary side of the insulated DC / DC inverter including the harmonic suppression inverter, and does not flow to the frame ground (FG). It is possible to provide a power supply device in which the voltage and the leakage current of harmonics are reduced, and harmonic wave countermeasures are sufficiently taken.

Further, since the switching elements of the two inverters can be fixed to one radiator, the mounting structure is simple.
In addition, the radiator installation space of the printed wiring board can be reduced.

Further, since the radiator to which the switching element of the inverter is attached is not a frame ground,
It is not necessary to apply the insulation distance and space distance between the primary side of the inverter and the frame ground specified in the standard for the insulation distance and space distance of the switching element attached to the radiator, and there is no restriction in the standard. Thus, the insulation distance and the space distance of the switching element attached to the radiator can be determined as needed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram and an explanatory diagram of a radiator structure according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram and a radiator structure explanatory diagram of a second embodiment of the present invention.

FIG. 3 is a circuit diagram and an explanatory diagram of a radiator structure according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram of a conventional device and an explanatory diagram of a radiator structure.

[Explanation of symbols]

 1: Inverter for suppressing harmonics 2: Insulated DC / DC converter 3a, 3b: Input terminal 4: Diode bridge for rectification 5, 6: Switching element 7: Transformer 8: Radiator 9: Printed wiring board 10: Frame ground terminal (FG terminal) 11a, 11b: output terminal 12, 13: input stack

Claims (3)

[Claims] 1. An inverter for suppressing harmonics, comprising: an inverter for suppressing harmonics; and an insulated DC / DC converter cascaded to the inverter for suppressing harmonics for insulating a primary side from a secondary side.
In a switching regulator power supply device having a DC converter, a radiator for natural air cooling, wherein each of the harmonic suppression inverter and the switching element of the insulated DC / DC inverter is arranged on a printed wiring board And the insulated DC including the radiator and the harmonic suppression inverter.
A switching regulator power supply device connected to a stable potential on the primary side of a DC converter. 2. The switching regulator power supply according to claim 1, wherein said radiator is directly connected to a positive side or a negative side of an input electrolytic capacitor provided in said harmonic suppression inverter. Regulator power supply. 3. The switching regulator power supply according to claim 1, wherein the radiator is connected to a positive side or a negative side of an input electrolytic capacitor provided in the harmonic suppression inverter via a capacitor. Characteristic switching regulator power supply.