Power supply device

Abstract

To provide a power supply device capable of suppressing the oscillation in a closed circuit containing a noise attenuation part.SOLUTION: In a power supply device 1, a main circuit 3 comprises: a core 30; a first common mold coil 31; a second common mold coil 32; a first connection wire 33; and a second connection wire 34. A noise attenuation part 5 includes: an auxiliary coil 50 having a third winding wire 50D and a third coated film 50E; a capacitor 54 connected to the first connection wire 33; and a low-pass filter 53 connected to an amplifier 52 and an output terminal of the amplifier 52, and comprises: a resonance suppression part 55 provided between the auxiliary coil 50 and the capacitor 54.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a power supply device. [Background technology]

[0002] Patent Document 1 discloses a power supply device. The power supply device described in Patent Document 1 includes a three-phase inverter of a neutral point clamp type (NPC) capable of outputting three levels and connected to a DC power source having three potentials to drive a three-phase load, a means for calculating a three-phase voltage command, a neutral point potential fluctuation suppressing means for calculating a zero-phase bias voltage compensation amount so as to suppress fluctuations in the neutral point potential according to the three-phase voltage command and the current flowing in the load current, and a means for adding the zero-phase bias voltage compensation amount to the three-phase voltage command for correction, and the neutral point potential fluctuation suppressing means includes a means for calculating the zero-phase bias voltage compensation amount according to at least the absolute value and sign of the three-phase voltage command and the load current. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-239564 A Summary of the Invention [Problem to be solved by the invention]

[0004] A known power supply device has a common mode choke coil and a noise attenuation section that attenuates noise generated in electronic devices (such as a switching section). The noise attenuation section detects a common mode current, amplifies a signal including the common mode current in an amplifier section, and generates an attenuation current to attenuate the noise. In this configuration, the gain of the closed circuit including the noise attenuation section (output voltage at a specified point in the closed circuit including the noise attenuation section / input voltage at a specified point in the closed circuit including the noise attenuation section) becomes high at the resonant frequency, and there is a risk of oscillation occurring in the closed circuit including the noise attenuation section. In this case, the noise attenuation section does not operate normally, and the noise cannot be attenuated.

[0005] An object of one aspect of the present invention is to provide a power supply device capable of suppressing oscillation in a closed circuit including a noise attenuation section. [Means for solving the problem]

[0006] A power supply device according to one aspect of the present invention is a power supply device including a main circuit, a switching unit connected to the main circuit, and a noise attenuation unit that attenuates noise generated in the switching unit, wherein the main circuit includes a core, a first common mode coil including a first winding and a first coating covering the first winding and wound around the core, and a second common mode coil including a second winding and a second coating covering the second winding and wound around the core, a first connecting wire that connects the first winding and the switching unit, and a second connecting wire that connects the second winding and the switching unit, and the noise attenuation unit includes an auxiliary coil having a third winding and a third coating covering the third winding, and wound around the core so that the third winding is separated from the first winding and the second winding by a predetermined insulation distance, a capacitor connected to at least one of the first connecting wire and the second connecting wire, and a resonance suppression unit having an amplifier unit and a low-pass filter connected to the amplifier unit and provided between the auxiliary coil and the capacitor.

[0007] In a power supply device according to one aspect of the present invention, the resonance suppression unit has a low-pass filter. With this, even when the amplifier unit amplifies a signal, the power supply device can suppress the occurrence of oscillation in a closed circuit including the noise attenuation unit. As a result, the power supply device can attenuate noise generated in the switching unit.

[0008] In one embodiment, the input terminal of the amplifier unit may be electrically connected to the third winding, and the output terminal of the amplifier unit may be electrically connected to a capacitor. In this configuration, a common mode current is detected in the third winding, and a signal including the common mode current is amplified in the amplifier unit to generate an attenuation current. This configuration also makes it possible to attenuate noise generated in the switching unit.

[0009] In one embodiment, the input terminal of the amplifier unit may be electrically connected to a capacitor, and the output terminal of the amplifier unit may be electrically connected to a third winding. In this configuration, a common-mode voltage is detected in the capacitor, and a signal including the common-mode voltage is amplified in the amplifier unit to generate an attenuation current. This configuration also makes it possible to attenuate noise generated in the switching unit.

[0010] In one embodiment, the capacitor is connected to the first connecting line, and the predetermined insulation distance may be a distance at which the gain of the closed circuit is 0 or less when the phase of the input and the phase of the output at a predetermined point of the closed circuit, which includes a parasitic capacitance generated between the first winding and the third winding, the third winding, the resonance suppression unit, the capacitor, and the first connecting line, become in phase. In the case of a power supply device in which a closed circuit is formed by the parasitic capacitance, the gain of the closed circuit (output voltage at a predetermined point in the closed circuit / input voltage at a predetermined point in the closed circuit) becomes high at a resonance frequency defined by the parasitic capacitance, and oscillation may occur in the closed circuit. In this configuration, the distance between the first winding and the third winding is set so that the gain of the closed circuit is 0 or less when the phase of the input and the phase of the output at a predetermined point in the closed circuit become in phase. Therefore, even if the gain of the closed circuit becomes high at a resonance frequency defined by the parasitic capacitance, it is possible to suppress the occurrence of oscillation in the closed circuit.

[0011] In addition, for example, when the low-pass filter is made smaller, the cutoff frequency becomes higher, and it may become impossible to reduce the gain at the resonant frequency. Therefore, by adjusting the insulation distance to reduce the parasitic capacitance and increase the resonant frequency, it is possible to suppress the occurrence of oscillation in the closed circuit even when the low-pass filter is made smaller.

[0012] In one embodiment, the auxiliary coil is wound on the first common mode coil, and the predetermined insulation distance may be the sum of the thickness of the third coating and the thickness of the first coating. In this configuration, the distance between the first winding and the third winding can be easily set to the predetermined insulation distance by winding the auxiliary coil on the first common mode coil and adjusting the thickness of the first coating and the thickness of the third coating.

[0013] In one embodiment, the thickness of the third coating may be greater than the thickness of the first coating, which allows the distance between the first and third windings to be easily set to a predetermined insulation distance without impairing the heat dissipation of the first winding, which generates more heat and has a larger current flowing through it than the third winding.

[0014] In one embodiment, the capacitor is connected to the first connecting wire, the auxiliary coil is wound around a portion of the core where the first common mode coil and the second common mode coil are not wound, and the predetermined insulation distance may be a distance at which the gain of the closed circuit is 0 or less when the phase of the input and the phase of the output at a predetermined point of the closed circuit, which includes the parasitic capacitance generated between the first winding and the third winding, the third winding, the resonance suppression unit, the capacitor, and the first connecting wire, become in phase. In the case of a power supply device in which a closed circuit is formed by the parasitic capacitance, the gain of the closed circuit (output voltage at a predetermined point in the closed circuit / input voltage at a predetermined point in the closed circuit) becomes high at a resonance frequency defined by the parasitic capacitance, and oscillation may occur in the closed circuit. In this configuration, the distance between the first winding and the third winding is set so that the gain of the closed circuit is 0 or less when the phase of the input and the phase of the output at a predetermined point in the closed circuit become in phase. Therefore, even if the gain of the closed circuit becomes high at a resonance frequency defined by the parasitic capacitance, it is possible to suppress the occurrence of oscillation in the closed circuit.

[0015] In addition, for example, when the low-pass filter is made smaller, the cutoff frequency becomes higher, and it may become impossible to reduce the gain at the resonant frequency. Therefore, by adjusting the insulation distance to reduce the parasitic capacitance and increase the resonant frequency, it is possible to suppress the occurrence of oscillation in the closed circuit even when the low-pass filter is made smaller.

[0016] In one embodiment, the capacitor is connected to the first connection line, the main circuit has a bobbin that houses a core, the first common mode coil and the second common mode coil are wound in a first region of the bobbin, the auxiliary coil is wound in a second region of the bobbin different from the first region, and the bobbin may have a protruding portion provided between the first region and the second region so that the first winding and the third winding are separated by a predetermined insulation distance. In this configuration, the protruding portion can extend the insulation distance between the third winding and the first winding.

[0017] In one embodiment, the first winding, the second winding, and the third winding each include a winding portion wound around a bobbin and terminal portions extending from both ends of the winding portion, the main circuit includes a substrate to which the terminal portion of the first winding, the terminal portion of the second winding, and the terminal portion of the third winding are connected, the bobbin includes a body portion that houses the core and on which the winding portion of the first winding, the winding portion of the second winding, and the winding portion of the third winding are wound, and legs that extend from the body portion toward the substrate and are installed on the substrate, and the legs may be provided between the terminal portion of the first winding and the terminal portion of the third winding. In this configuration, the legs can extend the insulation distance between the terminal portion of the first winding and the terminal portion of the third winding. Effect of the Invention

[0018] According to one aspect of the present invention, it is possible to suppress oscillation in a closed circuit including a noise attenuation section. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram showing a power supply device according to the first embodiment. [Diagram 2] FIG. 2(a) is a cross-sectional view of the first common mode coil, FIG. 2(b) is a cross-sectional view of the second common mode coil, and FIG. 2(c) is a cross-sectional view of the auxiliary coil. [Diagram 3] FIG. 3 is a diagram illustrating a configuration of the noise attenuation unit. [Figure 4] FIG. 4 is a cross-sectional view showing a state in which the first common mode coil and the auxiliary coil are wound around a core. [Diagram 5] FIG. 5 shows a state in which the first common mode coil and the auxiliary coil are wound around a bobbin in the power supply device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements are designated by the same reference numerals, and duplicated explanations will be omitted.

[0021] [First embodiment] Fig. 1 is a diagram showing a power supply device according to a first embodiment. As shown in Fig. 1, the power supply device 1 includes a main circuit 3, a noise attenuation unit 5, a switching unit 7, and a power supply 9. In the power supply device 1, noise generated in the switching unit 7 is attenuated by the noise attenuation unit 5. The power supply device 1 is connected to a load or the like and supplies power to the load or the like.

[0022] The main circuit 3 includes a core 30, a first common mode coil 31, a second common mode coil 32, a first connecting wire 33, and a second connecting wire 34. The core 30, the first common mode coil 31, and the second common mode coil 32 configure a common mode choke coil.

[0023] In the common mode choke coil, when a common mode current (hereinafter referred to as "common mode current") flows through the first common mode coil 31 and the second common mode coil 32, magnetic flux is generated by the electromagnetic induction phenomenon in the first common mode coil 31 and the second common mode coil 32. In this case, the generated magnetic fluxes are oriented in the same direction, and the magnetic fluxes reinforce each other, functioning as inductors. When a differential mode current flows through the first common mode coil 31 and the second common mode coil 32, the generated magnetic fluxes are oriented in opposite directions, and the magnetic fluxes cancel each other out. As a result, the coils do not function as inductors for differential mode currents.

[0024] The core 30 is made of a magnetic material and has an annular shape in the example shown in FIG.

[0025] The first common mode coil 31 includes a winding portion 31A wound around the core 30, and two terminal portions 31B, 31C extending from both ends of the winding portion 31A. As shown in FIG. 2(a), the first common mode coil 31 includes a first winding 31D and a first coating 31E. The first winding 31D is made of a conductive material. The first coating 31E covers the first winding 31D. The first coating 31E is made of an electrically insulating material. One end of the first common mode coil 31 (in other words, one end of the two terminal portions 31B, 31C) is connected to the power source 9. The other end of the first common mode coil 31 (in other words, the other end of the two terminal portions 31B, 31C) is connected to the first connection line 33.

[0026] As shown in FIG. 1, the second common mode coil 32 includes a winding portion 32A wound around the core 30, and two terminal portions 32B, 32C extending from both ends of the winding portion 32A. The second common mode coil 32 is wound around the core 30 in the opposite direction to the first common mode coil 31. As shown in FIG. 2(b), the second common mode coil 32 includes a second winding 32D and a second coating 32E. The second winding 32D is made of a material having electrical conductivity. The second coating 32E coats the second winding 32D. The second coating 32E is made of a material having electrical insulation. One end of the second common mode coil 32 (in other words, one end of the two terminal portions 32B, 32C) is connected to a power source 9. The other end of the second common mode coil 32 (in other words, the other end of the two terminal portions 32B, 32C) is connected to a second connection line .

[0027] 1, the first connecting line 33 connects the first winding 31D of the first common mode coil 31 and the switching unit 7. The first connecting line 33 has a conductor (not shown) and a coating (not shown) that covers the conductor. One end of the first connecting line 33 is connected to the other end of the first common mode coil 31. The other end of the first connecting line 33 is connected to the switching unit 7.

[0028] The second connection line 34 connects the second winding 32D of the second common mode coil 32 and the switching unit 7. The second connection line 34 has a conductor (not shown) and a coating (not shown) that covers the conductor. One end of the second connection line 34 is connected to the other end of the second common mode coil 32. The other end of the second connection line 34 is connected to the switching unit 7.

[0029] As shown in Fig. 3, the noise attenuation unit 5 has an auxiliary coil 50, a high-pass filter 51, an amplifier unit 52, a low-pass filter 53, and a capacitor 54. The amplifier unit 52 and the low-pass filter 53 configure a resonance suppression unit 55. In this embodiment, the amplifier unit 52 and the low-pass filter 53 are integrated, but for convenience of explanation, they are shown separately in Fig. 3. The noise attenuation unit 5 detects a common mode current in the auxiliary coil 50 and generates a current in opposite phase to the common mode current, thereby attenuating noise generated in the switching unit 7.

[0030] Here, in the power supply device 1, a first closed circuit C1 including a common mode choke coil and a capacitor 54, and a second closed circuit C2 formed by the first connecting line 33, a parasitic capacitance generated between the first winding 31D of the first common mode coil 31 and the third winding 50D of the auxiliary coil 50, the auxiliary coil 50, the high-pass filter 51, the amplifier section 52, the low-pass filter 53 and the capacitor 54.

[0031] In the first closed circuit C1, a first resonant frequency exists. The first resonant frequency is determined by the inductance of the first winding 31D of the first common mode coil 31 and the capacitor 54. At the first resonant frequency, the phase of the signal rotates by 180°.

[0032] In the second closed circuit C2, a second resonant frequency higher than the first resonant frequency exists. The second resonant frequency is determined by a parasitic capacitance between the first winding 31D of the first common mode coil 31 and the third winding 50D of the auxiliary coil 50, and a parasitic inductance in the second closed circuit C2. At the second resonant frequency, the phase of the signal rotates by 180°.

[0033] The auxiliary coil 50 includes a winding portion 50A wound around the core 30, and two terminal portions 50B, 50C extending from both ends of the winding portion 50A. As shown in FIG. 2(c), the auxiliary coil 50 includes a third winding 50D and a third coating 50E. The third winding 50D is made of a conductive material. The third coating 50E coats the third winding 50D. The third coating 50E is made of an electrically insulating material. Both ends of the auxiliary coil 50 (in other words, the ends of each of the two terminal portions 50B, 50C) are connected to the input terminals of the high-pass filter 51. The auxiliary coil 50 detects a common mode current in the core 30. The auxiliary coil 50 outputs the detected common mode current to the high-pass filter 51.

[0034] In this embodiment, the diameter of the third winding 50D of the auxiliary coil 50 is smaller than the diameters of the first winding 31D of the first common mode coil 31 and the second winding 32D of the second common mode coil 32. The diameter of the first winding 31D of the first common mode coil 31 is equivalent to the diameter of the second winding 32D of the second common mode coil 32. The thickness T3 of the third coating 50E of the auxiliary coil 50 is thicker than the thickness T1 of the first coating 31E of the first common mode coil 31 and the thickness T2 of the second coating 32E of the second common mode coil 32 (T3>T1, T2). The thickness T1 of the first coating 31E of the first common mode coil 31 is equivalent to the thickness T2 of the second coating 32E of the second common mode coil 32 (T1=T2).

[0035] As shown in Fig. 4, the auxiliary coil 50 of this embodiment is wound around the first common mode coil 31. Specifically, the first common mode coil 31 is wound around the core 30, and the auxiliary coil 50 is wound around the first common mode coil 31 so as to overlap the first common mode coil 31 wound around the core 30. That is, it can be said that the auxiliary coil 50 is wound around the core 30. The auxiliary coil 50 may be wound directly around the core 30 (may be in contact with the core 30). For convenience of explanation, Fig. 1 shows a state in which the first common mode coil 31 and the auxiliary coil 50 are wound in different positions (areas) with respect to the core 30, that is, the auxiliary coil 50 is wound so as not to be on the first common mode coil 31.

[0036] The first winding 31D of the first common mode coil 31 and the third winding 50D of the auxiliary coil 50 are separated by a predetermined insulation distance D. Specifically, the thickness T1 of the first coating 31E of the first common mode coil 31 and the thickness T3 of the third coating 50E of the auxiliary coil 50 are set so that the sum of the thickness T1 of the first coating 31E of the first common mode coil 31 and the thickness T3 of the third coating 50E of the auxiliary coil 50 is equal to the predetermined insulation distance D.

[0037] The predetermined insulation distance D defines a parasitic capacitance value generated between the first winding 31D of the first common mode coil 31 and the third winding 50D of the auxiliary coil 50. Therefore, by adjusting the predetermined insulation distance D, it is possible to adjust the second resonant frequency defined by the parasitic capacitance generated between the first winding 31D of the first common mode coil 31 and the third winding 50D of the auxiliary coil 50 and the parasitic inductance in the second closed circuit C2.

[0038] The specified insulation distance D is the distance at which the gain of the second closed circuit C2 is 0 or less when the input phase and the output phase at a specified location of the second closed circuit C2 (for example, the input terminal of the high-pass filter 51) become in phase.

[0039] In this embodiment, at the second resonant frequency, the phase of the signal rotates by 720° (i.e., the input phase and output phase of a specified point of the second closed circuit C2 are in phase), so the specified insulation distance D is set so that the gain of the second closed circuit C2 at the second resonant frequency is 0 or less.

[0040] As shown in FIG. 3, the high-pass filter 51 is a filter circuit that attenuates components below a set frequency (cut-off frequency) and extracts signals in a frequency band higher than the set frequency. The high-pass filter 51 may be configured to include, for example, a capacitor, a resistor, and the like. The auxiliary coil 50 is connected to an input terminal of the high-pass filter 51. The output terminal of the high-pass filter 51 is connected to an input terminal of the amplifier 52. When a signal including a common mode current output from the auxiliary coil 50 is input to the high-pass filter 51, the high-pass filter 51 attenuates components below the cut-off frequency. The high-pass filter 51 according to this embodiment is a third-order high-pass filter. In the high-pass filter 51, the phase of the input signal is rotated by 270°. The high-pass filter 51 outputs the processed signal to the amplifier 52.

[0041] The cutoff frequency of the high-pass filter 51 is set, for example, as follows. The main component of the signal detected in the auxiliary coil 50 is the switching frequency of the switching unit 7. The switching frequency of the switching unit 7 is, for example, about 20 to 60 kHz. The frequency of the noise to be attenuated in the noise attenuation unit 5 is, for example, about 150 to 500 kHz. Therefore, the cutoff frequency of the high-pass filter 51 is set so as to cut off low frequency components including the switching frequency. Furthermore, the cutoff frequency of the high-pass filter 51 is set to a frequency at which the gain of the second closed circuit C2 becomes 0 dB or less when the phase of the signal rotates 360°.

[0042] The amplifier 52 amplifies the signal. In this embodiment, the amplifier 52 is an inverting amplifier circuit. An inverting input terminal of the amplifier 52 is connected to the output terminal of the high-pass filter 51.

[0043] The low-pass filter 53 is a filter circuit that attenuates signals in a frequency band equal to or higher than a set frequency (cutoff frequency) and extracts signals in a frequency band lower than the set frequency. The low-pass filter 53 includes, for example, a capacitor, a resistor, and the like. In this embodiment, the low-pass filter 53 is integrated with the amplifier 52, and the capacitor and resistor constituting the low-pass filter 53 are connected between the inverting input terminal and the output terminal of the amplifier 52.

[0044] When the low-pass filter 53 receives the signal output from the amplifier 52, it attenuates components equal to or higher than the cutoff frequency. In the low-pass filter 53 according to this embodiment, the phase of the input signal is rotated by 90°. The low-pass filter 53 outputs the processed signal to the capacitor 54.

[0045] The cutoff frequency of the low-pass filter 53 is set to a frequency at which the gain of the second closed circuit C2 becomes 0 dB or less when the phase of the signal is rotated by 720°.

[0046] Here, the magnitude of the gain of the amplifier 52 is determined by the degree to which noise is to be attenuated. Therefore, in order for a designer to adjust the gain of the second closed circuit C2 when the input phase and the output phase at a predetermined point of the second closed circuit C2 become the same phase, it is necessary to adjust at least one of the cutoff frequency of the low-pass filter 53 and the high-frequency side resonance frequency.

[0047] The capacitor 54 is provided between the first connection line 33 and the output terminal of the amplifier unit 52. That is, the capacitor 54 is connected to the first connection line 33.

[0048] 1, the switching unit 7 has one or more switching elements (not shown). A switching element is an element that can electrically switch between open and closed states. Examples of switching elements that can be used include MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors), and bipolar transistors.

[0049] One end of the first common mode coil 31 and one end of the second common mode coil 32 are connected to the power source 9 .

[0050] As described above, in the power supply device 1 according to this embodiment, the noise attenuation unit 5 has the low-pass filter 53. This makes it possible to suppress the occurrence of oscillation in the second closed circuit C2 even when the signal is amplified in the amplifier unit 52 in the power supply device 1. As a result, the power supply device 1 can attenuate noise occurring in the switching unit 7.

[0051] In the power supply device 1 according to this embodiment, the thickness T3 of the third coating 50E of the auxiliary coil 50 is thicker than the thickness T1 of the first coating 31E of the first common mode coil 31. Since the current flowing through the auxiliary coil 50 is smaller than the current flowing through the first common mode coil 31 and the second common mode coil 32, the thickness T3 of the third coating 50E of the auxiliary coil 50 can be made thicker than the first coating 31E of the first common mode coil 31 and the second coating 32E of the second common mode coil 32.

[0052] Therefore, in this embodiment, the thickness T3 of the third coating 50E of the auxiliary coil 50 is adjusted to adjust the parasitic capacitance generated between the first winding 31D of the first common mode coil 31 and the third winding 50D of the auxiliary coil 50, thereby adjusting the high-frequency resonance frequency. For example, if the low-pass filter 53 is made smaller, the cutoff frequency becomes higher, and it may become impossible to reduce the gain at the high-frequency resonance frequency. Therefore, by increasing the thickness T3 of the third coating 50E of the auxiliary coil 50 to reduce the parasitic capacitance and increase the resonance frequency, it is possible to suppress the occurrence of oscillation in the second closed circuit C2 even when the low-pass filter 53 is made smaller.

[0053] In the power supply device 1 according to the present embodiment, the capacitor 54 is connected to the first connection line 33, and the predetermined insulation distance D is a distance at which the gain of the second closed circuit C2 becomes 0 or less when the phase of the input and the phase of the output at a predetermined point (for example, the input terminal of the high-pass filter 51) of the second closed circuit C2 become in phase. Therefore, even if the gain of the second closed circuit C2 becomes high at the resonance frequency defined by the parasitic capacitance, it is possible to suppress the occurrence of oscillation in the second closed circuit C2.

[0054] In the power supply device 1 according to this embodiment, the thickness T3 of the third coating 50E of the auxiliary coil 50 is thicker than the thickness T1 of the first coating 31E of the first common mode coil 31 and the thickness T2 of the second coating 32E of the second common mode coil 32. In this configuration, a current larger than that of the third winding 50D flows, and the distance between the first winding 31D and the third winding 50D can be easily set to a predetermined insulation distance D without impairing the heat dissipation of the first winding 31D, which generates more heat.

[0055] [Second embodiment] Next, a second embodiment will be described, which has the same configuration as the first embodiment except for the configuration of the common mode choke coil.

[0056] Fig. 5 shows a state in which the first common mode coil 31 and the auxiliary coil 50 are wound around a bobbin in the power supply device according to the second embodiment. As shown in Fig. 5, the common mode choke coil of the power supply device 1A includes a square tubular core (not shown) and a bobbin 35 that houses the core. The first common mode coil 31, the second common mode coil 32, and the auxiliary coil 50 are wound around the bobbin 35. The bobbin 35 is placed on a substrate 36. The second common mode coil 32 is not shown in Fig. 5.

[0057] The core of this embodiment is composed of four rectangular columns and four corners. The bobbin 35 has a main body 35A, a protruding portion 35B, and a leg portion 35C. The main body 35A is composed of four cylindrical portions covering the rectangular columns of the core and four connecting portions covering the corners of the core, and is a rectangular tube in overall view like the core. The main body 35A is formed to be one size larger than the core and accommodates the core. The main body 35A is also a portion around which the first common mode coil 31, the second common mode coil 32, and the auxiliary coil 50 are wound.

[0058] The first common mode coil 31, the second common mode coil 32 and the auxiliary coil 50 include winding portions 31A, 32A, 50A wound around the main body portion 35A of the bobbin 35, and terminal portions 31B, 31C, 32B, 32C, 50B, 50C extending from both ends of the winding portions 31A, 32A, 50A toward the substrate 36 and having ends connected to the substrate 36.

[0059] The first common mode coil 31, the second common mode coil 32, and the auxiliary coil 50 are wound in different regions in the main body 35A of the bobbin 35. That is, the first common mode coil 31, the second common mode coil 32, and the auxiliary coil 50 are wound in the main body 35A of the bobbin 35 so as not to overlap each other.

[0060] In this embodiment, of the four cylindrical portions, the second common mode coil 32 is wound around the cylindrical portion provided opposite to the cylindrical portion around which the first common mode coil 31 is wound, and the auxiliary coil 50 is wound around one of the cylindrical portions provided between the cylindrical portion around which the first common mode coil 31 is wound and the cylindrical portion around which the second common mode coil 32 is wound. That is, the cylindrical portion around which the first common mode coil 31 is wound and the cylindrical portion around which the second common mode coil 32 is wound correspond to the first region in the present invention, and the cylindrical portion around which the auxiliary coil 50 is wound corresponds to the second region in the present invention.

[0061] The protruding portion 35B is provided so as to protrude from a portion of the main body 35A where the first common mode coil 31, the second common mode coil 32, and the auxiliary coil 50 are not wound. The protruding portion 35B in this embodiment is provided at a connecting portion of the main body 35A. More specifically, the protruding portion 35B is provided at a connecting portion located between the cylindrical portion around which the first common mode coil 31 is wound and the cylindrical portion around which the auxiliary coil 50 is wound. That is, it can be said that the protruding portion 35B is provided between the first region and the second region of the main body 35A of the bobbin 35. The protruding portion 35B is provided to separate the first common mode coil 31 and the auxiliary coil 50 by a predetermined insulation distance D (see FIG. 4). The predetermined insulation distance D is the shortest distance between the first common mode coil 31 wound on the inner periphery side of the main body 35A and the auxiliary coil 50.

[0062] The legs 35C protrude from the portions of the main body 35A where the first common mode coil 31, the second common mode coil 32, and the auxiliary coil 50 are not wound (four connecting portions in this embodiment) in the opposite direction to the protruding direction of the convex portion 35B. Four legs 35C are provided. The legs 35C extend from the main body 35A toward the substrate 36. The legs 35C are fixed to the substrate 36. Of the four legs 35C, the legs 35C protruding from the connecting portions located between the cylindrical portion around which the first common mode coil 31 is wound and the cylindrical portion around which the auxiliary coil 50 is wound are provided to separate the terminal portions 31B, 31C of the first common mode coil 31 from the terminal portions 50B, 50C of the auxiliary coil 50 by a predetermined insulation distance D.

[0063] As described above, in the power supply device 1A according to this embodiment, like the power supply device 1, the noise attenuation unit 5 has the low-pass filter 53. This makes it possible to suppress the occurrence of oscillation in the second closed circuit C2 in the power supply device 1 even when the signal is amplified in the amplifier unit 52. As a result, the power supply device 1A can attenuate noise occurring in the switching unit 7.

[0064] In the power supply device 1A according to this embodiment, the protrusion 35B is provided at a connecting portion located between the cylindrical portion around which the first common mode coil 31 is wound and the cylindrical portion around which the auxiliary coil 50 is wound. In this configuration, the protrusion 35B can extend the insulation distance between the first winding 31D and the third winding 50D.

[0065] In the power supply device 1A according to this embodiment, the main circuit 3A has a substrate 36 to which the terminals of the first winding 31D of the first common mode coil 31, the second winding 32D of the second common mode coil 32, and the third winding 50D of the auxiliary coil 50 are connected. The bobbin 35 has a main body 35A that houses a core and on which the first winding 31D, the second winding 32D, and the third winding 50D are wound, and a leg 35C that extends from the main body 35A toward the substrate 36 and is installed on the substrate 36. The leg 35C is provided between the terminals 31B, 31C of the first winding 31D and the terminals 50B, 50C of the third winding 50D. In this configuration, the leg 35C can extend the insulation distance between the terminals 31B, 31C of the first winding 31D and the terminals 50B, 50C of the third winding 50D.

[0066] Although the embodiment of the present invention has been described above, the present invention is not necessarily limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention.

[0067] In the above first embodiment, the core is described as having an annular shape, and in the second embodiment, the core is described as having a rectangular cylindrical shape. However, the shape of the core is not limited thereto.

[0068] In the above embodiment, an example has been described in which the noise attenuation section 5 includes the high-pass filter 51. However, the high-pass filter 51 does not necessarily have to be provided.

[0069] In the above embodiment, an example has been described in which the amplifier 52 and the low-pass filter 53 are integrated together. However, the amplifier and the low-pass filter 53 may be configured separately. Also, the high-pass filter 51 and the amplifier 52 may be integrated together.

[0070] In the above embodiment, only a noise attenuation section 5 having a capacitor 54 connected to the first connection line 33 is provided, but this is not limited to this, and a noise attenuation section having a capacitor connected to the second connection line 34 may also be provided.

[0071] In addition to the above embodiment, the capacitor 54 and the resonance suppressor 55 may be connected via a resistor or the like.

[0072] In the above first embodiment, an example has been described in which the auxiliary coil 50 is wound around the first common mode coil 31. However, the auxiliary coil 50 may be wound only around the second common mode coil 32, or may be wound around both the first common mode coil 31 and the second common mode coil 32. When the auxiliary coil 50 is wound around the second common mode coil 32, the capacitor may be connected to the second connecting wire 34.

[0073] In the above second embodiment, the protrusion 35B is provided at a connecting portion located between the cylindrical portion around which the first common mode coil 31 is wound and the cylindrical portion around which the auxiliary coil 50 is wound. However, the protrusion 35B may be provided at a connecting portion located between the cylindrical portion around which the second common mode coil 32 is wound and the cylindrical portion around which the auxiliary coil 50 is wound.

[0074] In the above embodiment, an example has been described in which the input terminal of the amplifier 52 in the noise attenuation unit 5 is electrically connected to the third winding 50D of the auxiliary coil 50, and the output terminal of the amplifier 52 is electrically connected to the capacitor 54. However, the input terminal of the amplifier may be electrically connected to the capacitor, and the output terminal of the amplifier may be electrically connected to the third winding. In this configuration, the common mode voltage is detected by the capacitor, and a signal including the common mode voltage is amplified in the amplifier to generate an attenuation current. Then, the attenuation current is output to the transformer (coil) via the third winding, thereby making it possible to attenuate noise generated in the switching unit. [Explanation of symbols]

[0075] 1,1A...power supply device, 3,3A...main circuit, 5...noise attenuation section, 7...switching section, 30...core, 31...first common mode coil, 31A...winding section, 31B,31C...terminal section, 31D...first winding, 31E...first coating, 32...second common mode coil, 32A...winding section, 32B,32C...terminal section, 32D...second winding, 32E...second coating, 33...first connecting wire, 34...second connecting wire, 35...bobbin, 35A...main body, 35B...projection, 35C...leg, 36...substrate, 50...auxiliary coil, 50A...winding section, 50B,50C...terminal section, 50D...third winding, 50E...third coating, 52...amplification section, 53...low pass filter, 55...resonance suppression section, D...insulation distance.

Claims

1. A power supply device comprising: a main circuit; a switching unit connected to the main circuit; and a noise attenuation unit that attenuates noise generated in the switching unit, The main circuit includes: A core, a first common mode coil including a first winding and a first coating covering the first winding and wound around the core; and a second common mode coil including a second winding and a second coating covering the second winding and wound around the core; a first connection line connecting the first winding and the switching unit, and a second connection line connecting the second winding and the switching unit, The noise attenuation unit is an auxiliary coil including a third winding and a third coating that coats the third winding, the auxiliary coil being wound around the core such that the third winding is spaced apart from the first winding and the second winding by a predetermined insulation distance; a capacitor connected to at least one of the first connection line and the second connection line; a resonance suppression unit having an amplifier unit and a low-pass filter connected to the amplifier unit, the resonance suppression unit being provided between the auxiliary coil and the capacitor; the capacitor is connected to the first connection line; a power supply device, wherein the specified insulation distance is a distance at which the gain of a closed circuit having a parasitic capacitance generated between the first winding and the third winding, the third winding, the resonance suppression unit, the capacitor, and the first connecting line is 0 or less when the input phase and the output phase at a specified point of the closed circuit are in phase.

2. an input terminal of the amplifier unit is electrically connected to the third winding; The power supply device according to claim 1 , wherein an output terminal of the amplifier unit is electrically connected to the capacitor.

3. an input terminal of the amplifier unit is electrically connected to the capacitor; The power supply device according to claim 1 , wherein an output terminal of the amplifier unit is electrically connected to the third winding.

4. the auxiliary coil is wound around the first common mode coil, 4. The power supply device according to claim 1, wherein the predetermined insulation distance is a sum of a thickness of the third coating and a thickness of the first coating.

5. The power supply device of claim 4 , wherein the third coating has a thickness greater than a thickness of the first coating.

6. A power supply device comprising: a main circuit; a switching unit connected to the main circuit; and a noise attenuation unit that attenuates noise generated in the switching unit, The main circuit includes: A core, a first common mode coil including a first winding and a first coating covering the first winding and wound around the core; and a second common mode coil including a second winding and a second coating covering the second winding and wound around the core; a first connection line connecting the first winding and the switching unit, and a second connection line connecting the second winding and the switching unit, The noise attenuation unit is an auxiliary coil including a third winding and a third coating that coats the third winding, the auxiliary coil being wound around the core such that the third winding is spaced apart from the first winding and the second winding by a predetermined insulation distance; a capacitor connected to at least one of the first connection line and the second connection line; a resonance suppression unit having an amplifier unit and a low-pass filter connected to the amplifier unit, the resonance suppression unit being provided between the auxiliary coil and the capacitor; the capacitor is connected to the first connection line; the auxiliary coil is wound around a portion of the core where the first common mode coil and the second common mode coil are not wound, a power supply device, wherein the specified insulation distance is a distance at which the gain of a closed circuit having a parasitic capacitance generated between the first winding and the third winding, the third winding, the resonance suppression unit, the capacitor, and the first connecting line is 0 or less when the input phase and the output phase at a specified point of the closed circuit are in phase.

7. An input terminal of the amplifier unit is electrically connected to the third winding, The power supply device according to claim 6 , wherein an output terminal of the amplifier unit is electrically connected to the capacitor.

8. The input terminal of the amplifier is electrically connected to the capacitor, The power supply device according to claim 6 , wherein an output terminal of the amplifier section is electrically connected to the third winding.

9. the capacitor is connected to the first connection line; The main circuit has a bobbin that houses the core, the first common mode coil and the second common mode coil are wound around a first region of the bobbin, the auxiliary coil is wound in a second region of the bobbin that is different from the first region, The power supply device according to any one of claims 6 to 8, wherein the bobbin has a convex portion provided between the first region and the second region so that the first winding and the third winding are separated by the predetermined insulation distance.

10. the first winding, the second winding, and the third winding each include a winding portion wound around the bobbin and terminal portions extending from both ends of the winding portion; the main circuit has a substrate to which the terminal portion of the first winding, the terminal portion of the second winding, and the terminal portion of the third winding are connected, the bobbin has a main body portion that houses the core and around which the winding portion of the first winding, the winding portion of the second winding, and the winding portion of the third winding are wound, and a leg portion that extends from the main body portion toward the substrate and is placed on the substrate, The power supply device according to claim 9 , wherein the leg portion is provided between the terminal portion of the first winding and the terminal portion of the third winding.

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