JP2006129591A - Power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply device wherein the influence of current ripples on a load in common mode can be reduced. <P>SOLUTION: The power supply device includes an AC-DC converter 3 that converts alternating currents into direct currents, a filter 5 that reduces ripples contained in the direct-current output of the AC-DC converter 3, a first ground capacitor 15 provided on the input side of the AC-DC converter 3, and a second ground capacitor 16 provided on the output side of the filter 5. The grounding point of the first ground capacitor 15 and the grounding point of the second ground capacitor 16 are connected to first ground conductors 12a and 12b, and the first ground conductors are grounded at one point. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power supply device that supplies power to a load, and more particularly to a power supply device that reduces output ripple.

  For example, an electromagnetic power source for an accelerator used for medical / physical research needs to excite an electromagnetic coil with high accuracy in order to generate a high-energy proton beam. For this reason, the power source is required to reduce the normalized value (ΔIr / Io) of the current ripple ΔIr to 10 minus 6 or less with respect to the rated DC current Io.

  As a power supply device that reduces such current ripple, a high-order frequency component uses a low-pass filter, and a low-order frequency component is loaded with a series circuit of a self-extinguishing switching element such as an IGBT and a resistor. And a method of controlling on / off of the switching element so as to compensate for a low-frequency current ripple has been proposed (see, for example, Patent Document 1).

  In the power supply device disclosed in Patent Document 1, it is possible to improve the reduction effect of the low-pass filter by generally increasing the switching operation of the element and reduce the so-called normal mode (power supply line) current ripple. .

  However, due to this higher frequency, so-called common mode (between the power supply line and the ground) leakage current may occur in the stray capacitance of the component devices and loads constituting the power supply device, and the common mode current ripple may increase. In particular, in recent years, common mode ripple has become apparent due to switching of high voltage and large current accompanying an increase in capacity of a power supply device and an increase in stray capacitance accompanying an increase in the size of equipment.

As a means of suppressing common-mode high-frequency voltage (current) due to this stray capacitance, there is a method of providing a grounding capacitor, and a grounding capacitor that is sufficiently larger than the stray capacitance between the main circuit and the earth is installed on the AC line that is the input of the AC / DC converter A method of providing it has been proposed (see, for example, Patent Document 2).
Japanese Patent Laying-Open No. 2003-18846 (page 4-6, FIG. 3) JP-A-8-111984 (page 2-3, FIG. 1)

  According to the technique disclosed in Patent Document 2, it is possible to prevent a common mode high-frequency voltage from being generated on the power supply side, but there remains a problem that current ripple still occurs on the load side.

  The present invention has been made in view of the above, and an object of the present invention is to provide a power supply device that can reduce the influence of current ripple caused by the common mode on the load side.

  In order to achieve the above object, a power supply device of the present invention includes an AC / DC converter that converts AC to DC, a filter that reduces ripples included in the DC output of the AC / DC converter, and an input side of the AC / DC converter. A first grounding capacitor provided; and a second grounding capacitor provided on the output side of the filter; a grounding point of the first grounding capacitor; a grounding point of the second grounding capacitor; Is connected to a first ground conductor, and this first ground conductor is grounded at one point.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply device which can reduce the influence which the current ripple by a common mode has on a load side can be provided.

  Hereinafter, embodiments of a power supply device according to the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a power supply apparatus according to Embodiment 1 of the present invention.

  The three-phase AC voltage supplied from the AC power source 1 is stepped down by the input transformer 2 and supplied to the AC / DC converter 3. The AC / DC converter 3 converts AC input into DC output, and supplies DC to the load coil 6 via the DC reactor 4 and the low-pass filter 5. The load current is detected by the current detector 7 and used for the control portion of the AC / DC converter 3 (not shown).

  The AC / DC converter 3 is housed in the converter board 8, the DC reactor 4 is housed in the reactor board 9, and the low-pass filter 5 is housed in the filter board 10.

  In the MW class large-capacity power supply device, a water cooling system may be used for cooling the AC / DC converter 3 and the DC reactor 4, and a cooling water pipe 11 is drawn into the enclosure of each panel. The converter board 8, the reactor board 9 and the filter board 10 are respectively provided with ground buses 12a, 12b and 12c for grounding. Furthermore, these boards are structurally fixed to the ground via the channel base 13.

  The stray capacitances 14a and 14b are representative of stray capacitance existing between equipment in the panel housing, for example, the DC reactor 4 and the ground.

  A grounding capacitor 15 is provided on the input side of the AC / DC converter 3, and a grounding point which is a midpoint of the three phases is connected to the grounding bus 12a. A grounding capacitor 16 is provided on the output side of the AC / DC converter 3, and the grounding point, which is the middle point, is connected to the grounding bus 12c. These ground buses 12a, 12b and 12c are connected to each other, and are grounded at one point from the end of the ground bus 12c via the ground copper plate 17 to the ground electrode.

  In order to insulate the equipment constituting the power supply and the ground buses 12a, 12b and 12c from the ground on the upper part of the channel base 13 of the converter board 8, the reactor board 9 and the filter board 10 containing the equipment constituting the power supply. Insulating plate 19 is arranged. Similarly, insulating packings 18a, 18b and 18c are inserted into the flange joint portions of the cooling water pipe 11 with the casings of the converter panel 8, the reactor panel 9 and the filter panel 10, respectively, to insulate the ground. ing. The insulating structure of the insulating plate 19 and the insulating packings 18a, 18b, and 18c is configured to ensure insulation at the connecting portion by using an insulating bolt, an insulating collar, etc., although not shown.

  When the ripple compensation switching element (not shown) shown in Patent Document 1 described above is used in the housing of the filter panel 10, the grounding capacitor 16 is arranged on the output side thereof, and is connected to the AC terminal. The grounding capacitor 15 and the grounding capacitor 16 at the DC end are connected to the ground buses 12a and 12c so as to sandwich the switching element in the AC / DC converter 3 and the ripple compensator. The shield earth part of the input transformer 2 and the earth part of the load coil 6 are connected to a ground copper plate 17 (for example, a width of about 300 mm and a thickness of about 0.5 mm) having a lower impedance than the ground buses 12a, 12b and 12c. The grounding copper plate 17 is grounded at one point to a low impedance grounding electrode.

  The effects of the above configuration will be described below.

  First, common mode noise generated by switching of the AC / DC converter 3 flows out to the ground as a ground current via the floating capacitances 14a and 14b. The impedance of the floating capacitances 14a and 14b is caused by the grounding capacitor 15 on the AC side and the direct current. The ground leakage current due to the common mode noise circulates between the ground capacitor 15 at the AC end and the ground capacitor 16 at the DC end, and is thus converted to a converter. Leakage current flowing out from the panel 8, the reactor panel 9 and the filter panel 10 can be significantly reduced.

  Further, due to the insulating effect of the insulating plate 19 and the insulating packings 18a, 18b and 18c, the stray capacitances 14a and 14b can be limited to the stray capacitance of the ground buses 12a, 12b and 12c, thereby reducing the leakage current. In addition, the capacitance of the stray capacitances 14a and 14b can be reduced.

  In addition, the floating capacitance of the input transformer 2 and the floating capacitance of the load coil 6 that are mainly formed between the winding and the shield ground are easily formed via the grounded copper plate 17 having a low impedance, but the input transformer 2 Since the shield earth part and the earth part of the load coil 6 are directly grounded to the grounding copper plate 17, the leakage current from the transformer 2 and the load coil 6 can be reduced.

  Therefore, it is possible to suppress the leakage current from the power supply device components from appearing outside the panel, and it is possible to reduce the leakage current from the input transformer and the load coil to reduce the common mode ripple flowing in the load coil. Become.

  In FIG. 1 of the first embodiment, the AC / DC converter 3 is a so-called current type converter, but it may be a voltage type converter. In that case, the DC reactor 4 can be omitted.

  Next, a power supply device according to Embodiment 2 of the present invention will be described with reference to FIG.

  FIG. 2 is a configuration diagram of a power supply apparatus according to Embodiment 2 of the present invention. In each part of the second embodiment, the same parts as those of the power supply apparatus according to the first embodiment shown in FIG. The difference between the second embodiment and the first embodiment is that the input transformer 2 is housed in the transformer board 20 having the channel base 13a, and the shield earth portion of the transformer 2 is connected to the ground bus 12d in the board. An insulating plate 19a is provided between the ground bus 12d and the channel base 13a, and the ground bus 12d is grounded to the ground copper plate 17 at one point.

  By adopting such a configuration, it is possible to avoid a change in the path of stray capacitance formation due to contact between the transformer panel 20 and the converter panel 8, and to ground the input transformer 2 from the ground and to make a single point ground, The stray capacitance of the transformer 2 is limited to the grounding bus 12d to prevent leakage of common mode noise to other than the grounding copper plate 17.

  Therefore, it is possible to further reduce the leakage current from the input transformer and reduce the common mode ripple flowing in the load coil.

  Next, a power supply device according to Embodiment 3 of the present invention will be described with reference to FIG.

  FIG. 3 is a configuration diagram of a power supply device according to Embodiment 3 of the present invention. Regarding the parts of the third embodiment, the same parts as those of the power supply device according to the second embodiment of FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. The third embodiment is different from the second embodiment in that the load coil 6 is installed on the channel base 13b via the insulating plate 19b.

  By thus isolating the load coil 6 from the ground and grounding it at one point, the formation of the floating capacitance of the load coil 6 is limited to the grounded copper plate 17, and the leakage current from the load coil 6 is further reduced. Thus, the common mode ripple flowing in the load coil can be reduced.

  Next, a power supply device according to Embodiment 4 of the present invention will be described with reference to FIG.

  FIG. 4 is a configuration diagram of a power supply apparatus according to Embodiment 4 of the present invention. In the parts of the fourth embodiment, the same parts as those of the power supply apparatus according to the first embodiment of FIG. The fourth embodiment is different from the first embodiment in that a damping resistor 21 is inserted in the midpoint ground line of the low-pass filter 5.

  The low-pass filter 5 has a sufficiently large capacitance compared to the DC-side ground capacitor 16 and the stray capacitances 14a and 14b, and therefore, the main common mode ripple component flows to the ground portion. The circulation path of the ground current at this time becomes a route from the grounding capacitor 15 at the AC end to the midpoint grounding of the low-pass filter 5 via the leakage inductance of the DC reactor 4.

  If the damping resistor 21 is selected so as to suppress the resonant component of the leakage inductance of the grounding capacitor 15 and the DC reactor 4 in the return path, the common mode ripple of the low-pass filter 5 due to resonance can be reduced, and therefore the common mode flowing through the load coil. Ripple can be reduced.

  Next, a power supply device according to Embodiment 5 of the present invention will be described with reference to FIG.

  FIG. 5 is a configuration diagram of a power supply apparatus according to Embodiment 5 of the present invention. About each part of this Example 5, the same part as each part of the power supply device which concerns on Example 4 of FIG. 4 is shown with the same code | symbol, and the description is abbreviate | omitted. The fifth embodiment is different from the fourth embodiment in that a tuning filter 5a including two series circuits of a resistor, a reactor and a capacitor is connected in parallel with the low-pass filter 5, and the midpoint of the tuning filter 5a is damped. The point is that the ground is made through the resistor 21a.

  The tuning filter 5a reduces the frequency component based on the phase configuration and connection of the input transformer 2 (for example, the 12-phase component for a 12-phase transformer) and the output component of the AC / DC converter 3 with a particularly large ripple. Selected. Since the tuning filter 5a has a large capacitor capacity as in the above-described low-pass filter 5 and has a low impedance in the frequency component to be tuned, common mode ripple tends to flow. When the midpoint of the low-pass filter 5 and the tuning filter 5a is connected, there is a risk of resonance between the filters. Therefore, as with the low-pass filter 5, a damping resistor 21a is individually provided.

  If comprised in this way, it will become possible to suppress the resonance phenomenon of a low-pass filter and a tuning filter, and to reduce the common mode ripple of the electric current which flows into a load coil.

  Next, a power supply device according to Embodiment 6 of the present invention will be described with reference to FIGS.

  FIG. 6 is a configuration diagram of a power supply apparatus according to Embodiment 6 of the present invention. About each part of this Example 6, the same part as each part of the power supply device which concerns on Example 1 of FIG. 1 is shown with the same code | symbol, and the description is abbreviate | omitted. The sixth embodiment is different from the first embodiment in that the device portion excluding the AC power supply 1 and the load coil 6 in the configuration of FIG. 1 is a unit power supply device 100, and the AC power supply 1 is a unit in parallel with the unit power supply device 100. The point where the power supply device 101 is installed, the load coils 7a and 7b are connected in series to the positive and negative sides of the output of the unit power supply device 100, respectively, and the load coils 7c and 7d are connected to the positive and negative sides of the output of the unit power supply device 101, respectively. Are connected in series to the load coils 7b and 7c. Further, a ground copper plate 17a is provided for the unit power supply device 100, and the earth of the load coils 7a and 7b is connected to the ground copper plate 17a. 17a is connected to the grounding copper plate 17 for the unit power supply device 100, and similarly, a grounding copper plate 17b is provided for the unit power supply device 101, and the grounding of the load coils 7c and 7d is connected to the grounding copper plate. With connecting to 7b, a point which is adapted to connect the ground copper sheet 17b and a ground copper sheet 17c for the unit power supply 101. Note that portions related to the cooling water pipe 11 shown in FIG. 1 are omitted for simplicity.

  FIG. 7 is an image diagram for explaining the configuration diagram shown in FIG. As shown in FIG. 7, the power supply according to the sixth embodiment is actually not only two unit power supplies 100 and 101, but a plurality of unit power supplies and load coils are alternately connected to make a circuit. Thus, a series path is configured. This is because it is easier to handle the power supply device divided according to the voltage to be supplied to the load coil as the capacity of the device increases.

  As shown in FIG. 7, a plurality of load coils are divided into a plurality of groups, and a unit power supply device is prepared for each group. Then, a load coil grounding copper plate is provided according to a plurality of load coils shared by the unit power supply device, the load coil grounding copper plate and the grounding copper plate of the unit power supply device are connected with low impedance, and the unit power supply device The earthing portions of the plurality of load coils shared by are connected to the load coil grounding copper plate.

  If comprised in this way, with respect to the application of an accelerator where a plurality of unit power supply devices and a plurality of load coils are alternately connected in series, for example, the grounding portion of the load coil is equally grounded by a grounded copper plate that is close In addition, the distribution of the stray capacitance of the load coil can be equalized, and the common mode ripple flowing through the load coil can be reduced.

  In the above description of the first to sixth embodiments, the converter board, the reactor board, and the filter board constituting the power supply device are grounded using a grounding capacitor, and an insulating plate or an insulating packing is used. However, the present invention is not limited to the above-described configuration, and does not depend on the number of components of the power supply device, the method of dividing and storing in the panel, or the specific method of insulation. In addition, it is obvious that the same effect can be obtained even when the switching elements and units in the constituent devices are combined in multiple series or multiple parallel.

The block diagram of the power supply device which concerns on Example 1 of this invention. The block diagram of the power supply device which concerns on Example 2 of this invention. The block diagram of the power supply device which concerns on Example 3 of this invention. The block diagram of the power supply device which concerns on Example 4 of this invention. The block diagram of the power supply device which concerns on Example 5 of this invention. The block diagram of the power supply device which concerns on Example 6 of this invention. The image figure of the power supply device which concerns on Example 6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Input transformer 3 AC / DC converter 4 DC reactor 5 Low pass filter 5a Tuning filter 6, 6a, 6b, 6c, 6d Load coil 7 Current detector 8 Converter panel 9 Reactor panel 10 Filter panel 11 Cooling water piping 12 , 12a Ground bus bars 13, 13a, 13b Channel bases 14a, 14b Floating capacitances 15, 16 Grounding capacitors 17, 17a, 17b, 17c Grounding copper plates 18a, 18b, 18c Insulating packing 19, 19a, 19b Insulating plate 20 Transformer panel 100, 101 Unit power supply

Claims (10)

An AC / DC converter that converts AC to DC,
A filter for reducing ripples included in the DC output of the AC / DC converter;
A first grounding capacitor provided on the input side of the AC / DC converter;
A second grounding capacitor provided on the output side of the filter,
Connecting a ground point of the first ground capacitor and a ground point of the second ground capacitor to a first ground conductor;
A power supply apparatus characterized in that the first grounding conductor is grounded at one point.   The power supply apparatus according to claim 1, wherein a DC output of the AC / DC converter is supplied to the filter through a DC reactor.   The power supply apparatus according to claim 1, wherein the AC / DC converter, the filter, and the first ground conductor are grounded with an insulator.   The power supply device according to claim 2, wherein the AC / DC converter, the filter, the DC reactor, and the first ground conductor are ground-insulated with an insulator.   The power supply device according to claim 2, wherein a cooling water pipe for cooling at least one of the AC / DC converter, the filter, and the DC reactor is grounded by an insulator.   The input transformer of the AC / DC converter is insulated from the ground by an insulator, and the grounding portion of the input transformer is grounded at one point to a second grounding conductor connected to the one-point grounding point. The power supply device according to 1.   The load connected to the output side of the filter is insulated from the ground by an insulator, and the earth portion of the load is grounded at one point to a second ground conductor connected to the one-point grounding point. The power supply device according to 1.   The power supply apparatus according to claim 2, wherein a midpoint of the filter is grounded to the first ground conductor via a damping resistor.   9. The power supply device according to claim 8, wherein a tuning filter is connected in parallel with the filter, and a midpoint of the tuning filter is grounded to the first ground conductor via a tuning filter damping resistor. An AC / DC converter that converts AC to DC,
A filter for reducing ripples included in the DC output of the AC / DC converter;
A first grounding capacitor provided on the input side of the AC / DC converter;
A second grounding capacitor provided on the output side of the filter;
A unit power supply unit is configured with a first ground conductor that is connected to the ground point of the first grounding capacitor and the second grounding capacitor with a grounding wire and grounded at one point to the grounding electrode.
A plurality of unit power supply units and loads are alternately connected in series,
A third ground conductor is provided for each load divided by the voltage supplied by each of the unit power supply devices,
Connecting the third ground conductor and the corresponding earth portion of the divided load;
A power supply apparatus, wherein the first ground conductor and the third ground conductor are connected.

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