Switching power supply device

Abstract

To reduce the generation of common mode noise while suppressing heat generation and power loss.SOLUTION: A switching power supply device 10 comprises a power conversion circuit 20, a control circuit 30, a Y-capacitor 40, and a common mode choke coil 50. The control circuit 30 is electrically connected to the power conversion circuit 20 in a direct manner. The Y-capacitor 40 is connected to a DC power supply 91 side of the power conversion circuit 20, and is connected to a ground potential GNDs. The common mode choke coil 50 is connected to a DC power supply 92 side of the control circuit 30. A noise balance circuit is formed of a closed circuit consisting of the power conversion circuit 20, the control circuit 30, the Y-capacitor 40, and the common mode choke coil 50. The noise balance circuit confines and cancels out common mode currents, acting as switching noise, which are generated in a plurality of closed circuit portions as a result of switching operations of power conversion switching elements Q1 and Q2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a switching power supply device that performs power conversion using a switching element.

Background Art

[0002] In a switching power supply device, common mode noise generated by a switching element for power conversion becomes a problem. In particular, when handling a large amount of power, such as in a switching power supply device mounted on an electric vehicle, a large amount of EMI noise mainly occurs due to common mode noise, causing an electromagnetic interference problem.

[0003] As a configuration for reducing the generation of common mode noise, the power supply device of Patent Document 1 connects a common mode choke coil and a Y capacitor to the input side and the output side of the power conversion circuit. That is, in the power supply device of Patent Document 1, both a common mode choke coil and a Y capacitor are connected between an external DC power supply and the power conversion circuit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in order to suppress common mode noise, it is necessary to use a large-sized common mode choke coil that can pass a large current with high impedance characteristics.

[0006] When a common mode choke coil with high impedance is connected to the wiring line to a power conversion circuit through which a large current flows, problems such as increased heat generation and power loss in the common mode choke coil occur.

[0007] Accordingly, an object of the present invention is to provide a switching power supply device that can suppress heat generation and power loss and reduce the generation of common-mode noise. **Means for Solving the Problems**

[0008] The switching power supply device of this invention includes a power conversion circuit, a control circuit, a Y capacitor, and a common-mode choke coil. The power conversion circuit includes a first input capacitor, a power conversion switching element, and a first output capacitor, and converts the power supplied from the first DC power supply and outputs it to the load. The control circuit is directly electrically connected to the power conversion circuit. The control circuit includes a second input capacitor and a switching drive circuit, and generates a drive signal for the power conversion switching element using the power supplied from the second DC power supply. The Y capacitor is connected to the first DC power supply side of the power conversion circuit and is connected to the ground potential. The common-mode choke coil is connected to the second DC power supply side of the control circuit. A noise balance circuit is formed by a closed circuit constituted by the power conversion circuit, the control circuit, the Y capacitor, and the common-mode choke coil, and the noise balance circuit confines the common-mode current that becomes switching noise generated in a plurality of closed circuit portions due to the switching operation of the power conversion switching element and cancels them out with each other.

[0009] In this configuration, the common-mode choke coil is connected to the control circuit that is directly electrically connected to the power conversion circuit and has lower power than the power conversion circuit. And a Y capacitor is connected to the power conversion circuit. For this reason, leakage of the common-mode noise current is suppressed by the Y capacitor from the power conversion circuit to the first DC power supply side, and leakage of the common-mode noise current is suppressed by the common-mode choke coil from the power conversion circuit through the control circuit to the second DC power supply side. Thereby, the common-mode current that becomes common-mode noise is confined in the noise balance circuit and canceled out. And since the common-mode choke coil is not connected to the wiring line to the power conversion circuit through which a large current flows but is connected to the wiring line to the low-power control circuit, heat generation and power loss in the common-mode choke coil are suppressed.

Advantages of the Invention

[0010] According to this invention, it is possible to reduce the generation of common-mode noise current while suppressing heat generation and power loss.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

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Figure 10

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Figure 15

Embodiments for Carrying Out the Invention

[0012] [First Embodiment] The switching power supply device according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit block diagram showing the schematic configuration of the switching power supply device according to the first embodiment of the present invention. FIG. 2 is a circuit diagram showing an example of the circuit configuration of the switching power supply device according to the first embodiment of the present invention.

[0013] (Schematic Configuration and Schematic Operation of Switching Power Supply Device 10) As shown in FIGS. 1 and 2, the switching power supply device 10 includes a power conversion circuit 20, a control circuit 30, a Y capacitor 40, and a common mode choke coil 50.

[0014] As a schematic configuration, a DC power supply 91 is connected to the input terminal of the power conversion circuit 20. The DC power supply 91 is a high-voltage power supply, for example, a DC power supply of 100V to 1000V. The DC power supply 91 corresponds to the "first DC power supply" of the present invention.

[0015] A Y capacitor 40 is connected between the input terminal of the power conversion circuit 20 and the DC power supply 91. The Y capacitor 40 is connected to the ground potential GNDs. The ground potential GNDs is different from the ground potential to the earth, and is the reference potential of an electric vehicle or the like on which the switching power supply device 10 is mounted, for example, the same potential as the chassis of the electric vehicle.

[0016] A load 99 is connected to the output terminal of the power conversion circuit 20.

[0017] The input terminal of the control circuit 30 is connected to a DC power supply 92. The DC power supply 92 is a power supply with a voltage lower than that of the DC power supply 91, for example, a DC power supply of 12V to 14V. The negative electrode of the DC power supply 92 is connected to the ground potential GNDs. The DC power supply 92 corresponds to the "second DC power supply" of the present invention.

[0018] A common mode choke coil 50 is connected between the input terminal of the control circuit 30 and the DC power supply 92.

[0019] The control circuit 30 and the power conversion circuit 20 are connected. At this time, the control circuit 30 and the power conversion circuit 20 are directly electrically connected. Note that being directly electrically connected means that the control circuit 30 and the power conversion circuit 20 are connected without other electrical circuit elements being connected between the control circuit 30 and the power conversion circuit 20.

[0020] The control circuit 30 is powered by the DC power supply 92. The control circuit 30 generates drive signals for the power conversion switching elements Q1 and Q2 of the power conversion circuit 20 and outputs them to the power conversion switching elements Q1 and Q2.

[0021] The power conversion circuit 20 performs power conversion on the input voltage from the DC power supply 91 into an output voltage for the load 99 by switching the power conversion switching elements Q1 and Q2 on and off according to the drive signals from the control circuit 30, and outputs it to the load 99.

[0022] The switching operation of the power conversion switching elements Q1 and Q2 is a factor causing common mode noise according to the switching frequency.

[0023] Here, as described above, in the switching power supply device 10, a Y capacitor 40 is connected to the input terminal of the power conversion circuit 20, and the Y capacitor 40 is connected to the ground potential GNDs. Further, in the switching power supply device 10, a common mode choke coil 50 is connected to the input terminal of the control circuit 30.

[0024] Thereby, the power conversion circuit 20, the control circuit 30, the Y capacitor 40, and the common mode choke coil 50 can constitute a closed circuit (noise balance circuit) for common mode noise. Therefore, the common mode noise generated from the power conversion switching elements Q1 and Q2 of the power conversion circuit 20 does not leak to the DC power supplies 91 and 92 sides of the switching power supply device 10 and is confined within the noise balance circuit. The common mode noise confined within the noise balance circuit is canceled out because the phases are different.

[0025] As a result, the switching power supply device 10 can reduce the generation of common mode noise. And since the common mode choke coil 50 is connected to the input terminal of the control circuit 30, that is, the common mode choke coil 50 is not connected to the high-power side wiring line but is connected to the low-power side wiring line. Therefore, heat generation and power loss of the common mode choke coil 50 can be suppressed. Further, since the withstand voltage of the common mode choke coil 50 can be lowered, the common mode choke coil 50 can be miniaturized and made inexpensive. Thereby, a small and inexpensive switching power supply device 10 can be realized.

[0026] (An example of the specific circuit configuration of the switching power supply device 10) As shown in FIG. 2, the power conversion circuit 20 includes an input capacitor C11, an inductor L1, power conversion switching elements Q1 and Q2, and an output capacitor C12. The input capacitor C11 corresponds to the "first input capacitor" of the present invention, and the output capacitor C12 corresponds to the "first output capacitor" of the present invention.

[0027] One terminal of the input capacitor C11 is connected to the positive electrode of the DC power supply 91, and the other terminal of the input capacitor C11 is connected to the negative electrode of the DC power supply 91. One terminal of the inductor L1 is connected to the positive electrode of the DC power supply 91, and the other terminal of the inductor L1 is connected to the node between the drain of the power conversion switching element Q1 and the source of the power conversion switching element Q2.

[0028] The source of the power conversion switching element Q1 is connected to the negative electrode of the DC power supply 91 and the negative electrode side output terminal of the switching power supply device 10. The drain of the power conversion switching element Q2 is connected to the positive electrode side output terminal of the switching power supply device 10. An output capacitor C12 is connected between the positive electrode side output terminal and the negative electrode side output terminal of the switching power supply device 10. And a load 99 is connected between the positive electrode side output terminal and the negative electrode side output terminal.

[0029] The gate of the power conversion switching element Q1 and the gate of the power conversion switching element Q2 are connected to the gate driver IC311 and the gate driver IC321 of the control circuit 30. More specifically, the gate of the power conversion switching element Q1 and the gate driver IC311 are directly electrically connected, and the gate of the power conversion switching element Q2 and the gate driver IC321 are directly electrically connected.

[0030] The control circuit 30 includes a gate driver IC311, an isolation converter 312, a gate driver IC321, and an isolation converter 322. The gate driver IC311 and the gate driver IC321 correspond to the "switching drive circuit" of the present invention.

[0031] The input terminal of the isolation converter 312 is connected to the common mode choke coil 50, and the output terminal of the isolation converter 312 is connected to the gate driver IC311. The input terminal of the isolation converter 322 is connected to the common mode choke coil 50, and the output terminal of the isolation converter 322 is connected to the gate driver IC321.

[0032] The isolation converter 312 includes a capacitor C311, a capacitor C312, a switching element Q31, an isolation transformer TR31, and a rectifying element D31. The isolation converter 312 converts the DC voltage of the DC power supply 92 into a DC drive voltage of the gate driver IC311 and supplies it to the gate driver IC311. The capacitor C311 corresponds to the "second input capacitor" of the present invention.

[0033] The isolation converter 322 includes a capacitor C321, a capacitor C322, a switching element Q32, an isolation transformer TR32, and a rectifying element D32. The isolation converter 322 is connected between the common mode choke coil 50 and the gate driver IC321. The isolation converter 322 converts the DC voltage of the DC power supply 92 into a DC drive voltage of the gate driver IC321 and supplies it to the gate driver IC321. The capacitor C321 corresponds to the "second input capacitor" of the present invention.

[0034] The Y capacitor 40 includes a capacitor C41 and a capacitor C42. The capacitor C41 and the capacitor C42 are connected in series. The series circuit of the capacitor C41 and the capacitor C42 is connected between a positive electrode side wiring line for power conversion connected to the positive electrode of the DC power supply 91 and a negative electrode side wiring line for power conversion connected to the negative electrode of the DC power supply 91. The node between the capacitor C41 and the capacitor C42 is connected to the ground potential GNDs.

[0035] The common mode choke coil 50 is connected between the DC power supply 92 and the control circuit 30.

[0036] The switching power supply device 10 with such a configuration operates as follows schematically. The gate driver IC 311 is driven by the power supplied from the DC power supply 92 through the common mode choke coil 50 and the isolation converter 312, and generates a drive signal for the power conversion switching element Q1. The gate driver IC 321 is driven by the power supplied from the DC power supply 92 through the common mode choke coil 50 and the isolation converter 322, and generates a drive signal for the power conversion switching element Q2. The gate driver IC 311 and the gate driver IC 321 are synchronized, and the drive signal output by the gate driver IC 311 and the drive signal output by the gate driver IC 321 are set such that their on-periods do not overlap and their on-voltages are output alternately.

[0037] The power conversion switching element Q1 of the power conversion circuit 20 is switched and controlled by the drive signal from the gate driver IC 311, and the power conversion switching element Q2 is switched and controlled by the drive signal from the gate driver IC 321. Thereby, the power conversion circuit 20 converts the DC voltage of the DC power supply 92 into an output voltage for the load 99 by power conversion and supplies it to the load 99.

[0038] In such a configuration, the switching operations of the power conversion switching element Q1 and the power conversion switching element Q2 are the main causes of common mode noise generation.

[0039] However, by having the above-described configuration, the switching power supply device 10 can reduce the generation of common mode noise.

[0040] FIG. 3 is a schematic diagram showing the flow of the common-mode current according to the configuration of the present invention, and FIG. 4 is a schematic diagram showing the flow of the common-mode current according to a comparative configuration. In FIGS. 3 and 4, the thick arrows indicate the flow of the common-mode current. The comparative configuration is a configuration that does not include the Y capacitor 40 and the common-mode choke coil 50 of the present invention. By adopting the configuration of the present invention, the illustrated common-mode current is ultimately suppressed, but for the sake of easy understanding of the explanation, the flow of the common-mode current is illustrated in FIG. 3.

[0041] The common-mode current is generated by the power conversion switching elements Q1 and Q2, which are noise sources, and flows through the lines that are electrically directly or indirectly connected in the frequency band of the common-mode noise. Therefore, the common-mode current flows not only through the power conversion circuit 20 but also through the control circuit 30.

[0042] As shown in FIG. 4, in the comparative configuration, by not providing the Y capacitor 40, the common-mode current flowing through the wiring lines for power conversion leaks from the power conversion circuit 20 of the switching power supply device 10 to the DC power supply 91 side. Similarly, in the comparative configuration, by not providing the common-mode choke coil 50, the common-mode current leaks from the control circuit 30 of the switching power supply device 10 to the DC power supply 92 side. Thus, in the comparative configuration, the common-mode current leaks outside the switching power supply device 10.

[0043] On the other hand, as shown in FIG. 3, in the present application configuration, since the common-mode choke coil 50 is connected to the input side of the control circuit 30, the common-mode current from the control circuit 30 to the DC power supply 92 side is suppressed.

[0044] Furthermore, in the configuration of the present application, a Y capacitor 40 is connected to the input side of the power conversion circuit 20, and the Y capacitor 40 is connected to the ground potential GNDs. As a result, the common-mode current is refluxed to the power conversion switching elements Q1 and Q2, which are noise sources, by the power conversion circuit 20, the Y capacitor 40, and the ground potential GNDs. At this time, since the phases of the common-mode currents are different from each other, they cancel each other out. Therefore, the generation of common-mode noise is reduced.

[0045] Thus, by using the configuration of the present application, the switching power supply device 10 can realize a closed circuit for the common-mode current by the power conversion circuit 20, the control circuit 30, the Y capacitor 40, and the common-mode choke coil 50, and balance the noise. That is, the switching power supply device 10 can be provided with a noise balancing circuit including the power conversion circuit 20, the control circuit 30, the Y capacitor 40, and the common-mode choke coil 50. As a result, the common-mode noise generated from the power conversion switching elements Q1 and Q2 of the power conversion circuit 20 is confined within the noise balancing circuit, and the leakage of the common-mode noise to the DC power supplies 91 and 92 sides is suppressed. Furthermore, the confined common-mode noise is canceled out because the phases are different from each other.

[0046] Note that the fact that the common-mode current is confined and canceled out by such a noise balancing circuit can be confirmed by connecting a LISN (Line Impedance Stabilization Network) to the Hi-side wiring line and the Low-side wiring line of the noise balancing circuit (see, for example, FIG. 3).

[0047] For example, the voltage of common-mode noise (common-mode noise voltage) is measured using a delta-type Lisn. FIGS. 5 and 6 are diagrams showing circuit examples when measuring common-mode noise using a delta-type Lisn. In FIG. 5, a delta-type Lisn is connected to the Lisn, and a spectrum analyzer is connected to the delta-type Lisn. In FIG. 6, a delta-type Lisn is connected between a DC power supply 91 and a half-bridge capacitor 41, and a spectrum analyzer is connected to the delta-type Lisn. If the common-mode noise voltage measured in these measurement configurations (measurement methods) is approximately 0 or sufficiently small, it can be detected that the common-mode current has been confined and canceled by the noise balance circuit.

[0048] Also, a current detection probe is arranged on the cable on the Hi side and the cable on the Low side, or on the cable connecting the Lisn and the chassis, and the common-mode current is measured with this probe. FIG. 7 is a circuit diagram when a current detection probe PRcr is arranged on the cable on the Hi side and the cable on the Low side. FIG. 8 is a circuit diagram when a current detection probe PRcr is arranged on the cable connecting the Lisn and the chassis. In the configurations of FIGS. 7 and 8, a spectrum analyzer is connected to the current detection probe PRcr. If the common-mode current is approximately 0 or sufficiently small in these measurement configurations (measurement methods), it can be detected that the common-mode current has been confined and canceled by the noise balance circuit.

[0049] Therefore, the switching power supply device 10 can reduce the generation of common-mode noise and achieve EMI noise suppression and power integrity (ensuring power quality).

[0050] That is, the switching power supply device 10 does not need to connect a common mode choke coil to the wiring line to the power conversion circuit through which a large current flows, and cancels noise generation at the noise source, suppressing heat generation and power loss in the common mode choke coil while reducing the generation of common mode noise current. In particular, it can effectively reduce the generation of common mode noise current while suppressing heat generation and power loss in the common mode choke coil for a switching power supply device that is difficult to ground the earth as the ground potential by moving, such as an electric vehicle.

[0051] FIG. 9 is a graph showing noise levels in the configuration of the present application and the comparative configuration. As shown in FIG. 9, by adopting the invention of the present application, noise in the 2 MHz to 20 MHz band can be suppressed. In particular, noise in the 5 MHz band can be more effectively suppressed.

[0052] Furthermore, the switching power supply device 10 does not connect the common mode choke coil 50 to the wiring line for power conversion, but connects it to the wiring line for low-power control. Thereby, heat generation of the common mode choke coil 50 can be suppressed. Therefore, the switching power supply device 10 can reduce the generation of common mode noise while suppressing heat generation and power loss.

[0053] Furthermore, there is no need to increase the withstand voltage of the common mode choke coil 50, and it can be miniaturized. Therefore, the switching power supply device 10 can reduce the generation of common mode noise while achieving miniaturization.

[0054] In particular, the switching power supply device 10 is more effective when mounted on an electric vehicle. Specifically, the common-mode noise generated by the switching operation of the power conversion circuit 20 may conduct through the chassis (components at the same potential as the ground potential GNDs), causing electromagnetic interference problems with other electronic circuits of the vehicle. For example, when common-mode noise flows into the control circuit of other electronic circuits of the vehicle, it may lead to malfunction problems in the control operation of the switching element in this control circuit. Also, when common-mode noise reaches other devices, it may cause malfunction problems in other devices. When common-mode noise radiates from the chassis, it may cause malfunction problems in electronic devices outside the vehicle.

[0055] However, by providing the configuration of the switching power supply device 10, leakage of common-mode noise from the switching power supply device 10 to the outside can be suppressed, and the occurrence of the above problems can be suppressed. In particular, in an electric vehicle, a very large current and voltage are input to the power conversion circuit 20. Therefore, the configuration of the switching power supply device 10 of the present invention is more effective.

[0056] Also, in the switching power supply device 10, the negative electrode of the DC power supply 92 is connected to the ground potential GNDs, and the positive and negative electrodes of the DC power supply 91 are not connected to the ground potential GNDs. Thereby, the switching power supply device 10 can stabilize the operation of the control circuit 30 while suppressing adverse effects on the outside through the DC power supply 91 with a large voltage and current.

[0057] Also, in the switching power supply device 10, the negative electrode of the gate driver IC 311 is connected to the source of the power conversion switching element Q1, and the negative electrode of the gate driver IC 321 is connected to the source of the power conversion switching element Q2. Thereby, the switching power supply device 10 can supply stable drive signals to the power conversion switching elements Q1 and Q2.

[0058] Note that the isolation converters 312 and 322 of the control circuit 30 can be replaced with non-isolation converters. However, by providing the isolation converters 312 and 322, the gate driver ICs 311 and 321 can be more reliably protected electrically from the DC power supply 92 side.

[0059] Also, the isolation converter 312 of the control circuit 30 is provided with a switching element Q31, and the isolation converter 322 is provided with a switching element Q32. However, in the switching power supply device 10, these switching elements Q31 and Q32 also exist within the noise balance circuit. Therefore, the switching power supply device 10 can also reduce the generation of common mode noise of the switching elements Q31 and Q32.

[0060] Also, in the switching power supply device 10, a Y capacitor may be further provided on the output side of the power conversion circuit 20.

[0061] Also, the configuration of the control circuit 30 is an example, and any other configuration may be used as long as it includes an input capacitor for the control circuit, gate driver ICs 311 and 321, and can output the above-described drive signals to the power conversion switching elements Q1 and Q2 of the power conversion circuit 20. Similarly, the power conversion circuit 20 may have any other configuration as long as it includes an input capacitor C11, power conversion switching elements Q1 and Q2, and an output capacitor C12.

[0062] [Second Embodiment] The switching power supply device according to the second embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a circuit diagram showing an example of the circuit configuration of the switching power supply device according to the second embodiment of the present invention.

[0063] As shown in FIG. 10, the switching power supply device 10A according to the second embodiment is different from the switching power supply device 10 according to the first embodiment in that it includes a heat sink 60. Other configurations of the switching power supply device 10A are the same as those of the switching power supply device 10, and descriptions of the same parts are omitted.

[0064] The switching power supply device 10 includes a heat sink 60. The heat sink 60 is made of a material with high thermal conductivity. The heat sink 60 is arranged in proximity to or in contact with the power conversion switching elements Q1 and Q2. In other words, the heat sink 60 is arranged at a position where the heat of the power conversion switching elements Q1 and Q2 is propagated. The heat sink 60 dissipates the heat generated in the power conversion switching elements Q1 and Q2.

[0065] Furthermore, the heat sink 60 has conductivity. That is, the heat sink 60 has high thermal conductivity and conductivity. The heat sink 60 is connected to the ground potential GNDs.

[0066] In this configuration, the noise radiated from the power conversion switching elements Q1 and Q2 flows to the ground potential GNDs through the heat sink 60. Thereby, the noise balance circuit is configured to include the heat sink 60.

[0067] Therefore, the noise balance circuit can balance including the noise radiated from the power conversion switching elements Q1 and Q2. As a result, the switching power supply device 10 can more effectively suppress the noise leaking to the outside. In particular, by arranging the heat sink 60 so as to overlap the power conversion switching elements Q1 and Q2, the switching power supply device 10 can more effectively suppress the noise leaking to the outside.

[0068] [Third Embodiment] The switching power supply device according to the third embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a circuit diagram showing an example of the circuit configuration of the switching power supply device according to the third embodiment of the present invention.

[0069] As shown in FIG. 11, the switching power supply device 10B according to the third embodiment is different from the switching power supply device 10A according to the second embodiment in the connection mode of the heat sink 60. Other configurations of the switching power supply device 10B are the same as those of the switching power supply device 10A, and descriptions of the same parts are omitted.

[0070] In the switching power supply device 10B, the heat sink 60 is connected to the wiring line on the control circuit 30 side on the negative electrode side of the common mode choke coil 50.

[0071] With such a configuration, the noise radiated from the power conversion switching elements Q1 and Q2 flows into the noise balance circuit through the heat sink 60 and the isolation converter 312. Then, since the heat sink 60 and the isolation converter 312 are connected to the wiring line on the control circuit 30 side on the negative electrode side of the common mode choke coil 50 (the negative electrode side of the DC power supply 92 connected to the ground potential GNDs), the noise passing through the heat sink 60 and the isolation converter 312 can be suppressed from leaking to the outside and from affecting the control circuit 30.

[0072] [Fourth Embodiment] The switching power supply device according to the fourth embodiment of the present invention will be described with reference to the drawings. FIG. 12 is a circuit diagram showing an example of the circuit configuration of the switching power supply device according to the fourth embodiment of the present invention.

[0073] As shown in FIG. 12, the switching power supply device 10C according to the fourth embodiment is different from the switching power supply device 10A according to the second embodiment in the connection mode of the heat sink 60. Other configurations of the switching power supply device 10C are the same as those of the switching power supply device 10A, and descriptions of the same parts are omitted.

[0074] In the switching power supply device 10C, the heat sink 60 is connected to the wiring line on the control circuit 30 side on the positive electrode side of the common mode choke coil 50.

[0075] With such a configuration, the noise radiated from the power conversion switching elements Q1 and Q2 flows into the noise balance circuit through the heat sink 60 and the isolation converter 312. Then, since the heat sink 60 is connected to the positive electrode side of the common mode choke coil 50 (the positive electrode side of the DC power supply 92 connected to the ground potential GNDs), and the isolation converter 312 is connected to the negative electrode side of the common mode choke coil 50 (the negative electrode side of the DC power supply 92 connected to the ground potential GNDs) to the wiring line on the control circuit 30 side, the noise passing through the heat sink 60 and the isolation converter 312 can be prevented from leaking to the outside and the influence on the control circuit 30 can be suppressed.

[0076] [Fifth Embodiment] The switching power supply device according to the fifth embodiment of the present invention will be described with reference to the drawings. FIG. 13 is a circuit diagram showing an example of the circuit configuration of the switching power supply device according to the fifth embodiment of the present invention.

[0077] As shown in FIG. 13, the switching power supply device 10D according to the fifth embodiment is different from the switching power supply device 10A according to the second embodiment in the connection mode of the heat sink 60. Other configurations of the switching power supply device 10D are the same as those of the switching power supply device 10A, and the description of the same parts will be omitted.

[0078] In the switching power supply device 10D, the heat sink 60 is connected to the negative electrode side of the Y capacitor 40 and to the wiring line on the power conversion circuit 20 side.

[0079] With such a configuration, the noise radiated from the power conversion switching elements Q1 and Q2 flows into the noise balance circuit through the isolation converter 312. Then, since the isolation converter 312 is connected to the negative electrode side of the common mode choke coil 50 (the negative electrode side of the DC power supply 92 connected to the ground potential GNDs) to the wiring line on the control circuit 30 side, the noise passing through the isolation converter 312 can be prevented from leaking to the outside and the influence on the control circuit 30 can be suppressed.

[0080] [Sixth Embodiment] A switching power supply device according to a sixth embodiment of the present invention will be described with reference to the drawings. FIG. 14 is a circuit diagram showing an example of the circuit configuration of the switching power supply device according to the sixth embodiment of the present invention.

[0081] As shown in FIG. 14, a switching power supply device 10E according to the sixth embodiment differs from the switching power supply device 10A according to the second embodiment in the connection mode of the heat sink 60. Other configurations of the switching power supply device 10E are the same as those of the switching power supply device 10A, and the description of the same parts will be omitted.

[0082] In the switching power supply device 10E, the heat sink 60 is connected to the wiring line on the power conversion circuit 20 side on the positive electrode side of the Y capacitor 40.

[0083] With such a configuration, the noise radiated from the power conversion switching elements Q1 and Q2 flows into the noise balance circuit through the isolation converter 312. Then, since the isolation converter 312 is connected to the wiring line on the control circuit 30 side on the negative electrode side of the common mode choke coil 50 (the negative electrode side of the DC power supply 92 connected to the ground potential GNDs), the noise passing through the isolation converter 312 can be suppressed from leaking to the outside and from affecting the control circuit 30.

[0084] [Seventh Embodiment] A switching power supply device according to a seventh embodiment of the present invention will be described with reference to the drawings. FIG. 15 is a circuit block diagram showing the schematic configuration of the switching power supply device according to the seventh embodiment of the present invention.

[0085] As shown in FIG. 15, a switching power supply device 10F according to the seventh embodiment differs from the switching power supply device 10 according to the first embodiment in that DC power is supplied from one DC power supply 91. Other configurations of the switching power supply device 10F are the same as those of the switching power supply device 10, and the description of the same parts will be omitted.

[0086] The switching power supply device 10F is connected to a DC power supply 91. A step-down circuit 39 is connected between the common-mode choke coil 50 and the DC power supply 91. The step-down circuit 39 is, for example, a step-down type DC-DC converter.

[0087] With such a configuration, like the switching power supply device 10, the switching power supply device 10F can reduce the generation of common-mode noise while suppressing heat generation and power loss. Also, in the configuration of the switching power supply device 10F, it does not require a plurality of DC power supplies with different voltages, and with a single DC power supply, it can reduce the generation of common-mode noise while suppressing heat generation and power loss.

[0088] Note that the configurations of the above-described embodiments can be combined as appropriate, and the effects corresponding to each combination can be achieved.

[0089] (1) A power conversion circuit including a first input capacitor, a power conversion switching element, and a first output capacitor, which converts the power supplied from a first DC power supply and outputs it to a load, A control circuit including a second input capacitor and a switching drive circuit, which generates a drive signal for the power conversion switching element using the power supplied from a second DC power supply and is directly electrically connected to the power conversion circuit, A Y capacitor connected to the first DC power supply side of the power conversion circuit and connected to the ground potential, A common-mode choke coil connected to the second DC power supply side of the control circuit, Comprising, A switching power supply device comprising a closed circuit formed by the power conversion circuit, the control circuit, the Y capacitor, and the common-mode choke coil, which forms a noise balance circuit that confines the common-mode current, which becomes switching noise generated in a plurality of closed circuit portions due to the switching operation of the power conversion switching element, and cancels them out with each other.

[0090] (2) The negative electrode of the second DC power supply is connected to the ground potential, and the switching power supply device of (1).

[0091] (3) The positive and negative electrodes of the first DC power supply are electrically insulated from the ground potential, and the switching power supply device according to (1) or (2).

[0092] (4) The voltage of the first DC power supply is higher than the voltage of the second DC power supply, and the switching power supply device according to any one of (1) to (3).

[0093] (5) The switching power supply device according to any one of (1) to (4), comprising a heat sink for dissipating heat generated in the power conversion switching element.

[0094] (6) The heat sink of the switching power supply device of (5) is connected to the ground potential.

[0095] (7) The heat sink is electrically connected to the negative electrode of the second DC power supply, The common mode choke coil is connected between the connection point of the heat sink and the second DC power supply and the positive electrode of the second DC power supply, and the switching power supply device of (5) or (6).

[0096] (8) The heat sink is electrically connected to the positive electrode of the second DC power supply, The common mode choke coil is connected between the connection point of the heat sink and the second DC power supply and the negative electrode of the second DC power supply, and the switching power supply device of (5) or (6).

[0097] (9) The heat sink is electrically connected to the negative electrode of the first DC power supply, and the switching power supply device of (5) or (6).

[0098] (10) The heat sink is electrically connected to the positive electrode of the first DC power supply, and the switching power supply device according to (5) or (6).

[0099] (1) The negative electrodes of the first DC power supply and the second DC power supply are electrically connected, and the switching power supply device according to any one of (1) to (10).

[0100] (12) The control circuit includes an isolation converter and a plurality of the switching drive circuits. The negative electrodes of the plurality of switching drive circuits are respectively connected to the source potentials of the plurality of power conversion switching elements, and the switching power supply device according to any one of (1) to (11).

[0101] (13) The noise balance circuit, the first DC power supply, and the second DC power supply are mounted on a vehicle. The ground potential is at the same potential as the chassis of the vehicle, and the switching power supply device according to any one of (1) to (12).

Explanation of Signs

[0102] 10, 10A, 10B, 10C, 10D, 10E, 10F: Switching power supply device 20: Power conversion circuit 30: Control circuit 39: Step-down circuit 40: Y capacitor 50: Common mode choke coil 60: Heat sink 91: DC power supply 92: DC power supply 99: Load 311, 321: Gate driver IC 312, 322: Isolation converter

Claims

1. A power conversion circuit including a first input capacitor, a power conversion switching element, and a first output capacitor, for converting power supplied from a first DC power supply and outputting the power to a load; A control circuit directly electrically connected to the power conversion circuit, including a second input capacitor and a switching drive circuit, for generating a drive signal for the power conversion switching element using power supplied from a second DC power supply; A Y capacitor connected to the first DC power supply side of the power conversion circuit and connected to the ground potential; A common mode choke coil connected to the second DC power supply side of the control circuit; Comprising: It consists of a closed circuit formed by the power conversion circuit, the control circuit, the Y capacitor, and the common mode choke coil, and forms a noise balance circuit that confines and cancels out each other the common mode current that becomes switching noise generated in a plurality of closed circuit portions by the switching operation of the power conversion switching element. A switching power supply device.

2. The negative electrode of the second DC power supply is connected to the ground potential. The switching power supply device according to claim 1.

3. The positive and negative electrodes of the first DC power supply are electrically insulated from the ground potential. The switching power supply device according to claim 1 or claim 2.

4. The voltage of the first DC power supply is higher than the voltage of the second DC power supply. The switching power supply device according to claim 1 or claim 2.

5. Comprising a heat sink for dissipating heat generated in the power conversion switching element. The switching power supply device according to claim 1 or claim 2.

6. The heat sink is connected to the ground potential. The switching power supply device according to claim 5.

7. The heat sink is electrically connected to the negative electrode of the second DC power supply. The common mode choke coil is connected between the connection point of the heat sink and the second DC power supply and the positive electrode of the second DC power supply. The switching power supply device according to claim 5.

8. The heat sink is electrically connected to the positive electrode of the second DC power supply. The common mode choke coil is connected between the connection point of the heat sink and the second DC power supply and the negative electrode of the second DC power supply. The switching power supply device according to claim 5.

9. The heat sink is electrically connected to the negative electrode of the first DC power supply. The switching power supply device according to claim 5.

10. The heat sink is electrically connected to the positive electrode of the first DC power supply. The switching power supply device according to claim 5.

11. The negative electrode of the first DC power supply and the negative electrode of the second DC power supply are electrically connected. The switching power supply device according to claim 1 or claim 2.

12. The control circuit includes an isolation converter and a plurality of the switching drive circuits. The negative electrodes of the plurality of switching drive circuits are respectively connected to the source potentials of the plurality of power conversion switching elements. The switching power supply device according to claim 1 or claim 2.

13. The noise balance circuit, the first DC power supply, and the second DC power supply are mounted on a vehicle. The ground potential is the same potential as the chassis of the vehicle. The switching power supply device according to claim 1 or claim 2.

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