JP4621767B2 - Voltage converter and electric load driving device - Google Patents

Description

  The present invention relates to a voltage conversion device including a first loop circuit and a second loop circuit sharing an inductance component, and an electric load driving device using the voltage conversion device.

Conventionally, in a switching power supply circuit having a primary side circuit connected to a primary coil of a transformer and a secondary side circuit connected to a secondary coil of the transformer, an electrode pattern on the primary side circuit side and a secondary side circuit By placing the electrode pattern on the opposite side, the insulation layer between the electrode patterns functions as a dielectric for the capacitor to form an equivalent capacitor, and the equivalent capacitor forms a noise countermeasure capacitor. The technique to do is known (for example, refer patent document 1).
JP 2005-110552 A

  By the way, in a non-insulated DC-DC converter that does not use a transformer, for example, as shown in FIG. 1, a first loop circuit and a second loop circuit that share an inductance L and have capacitors C1 and C2, respectively, are provided. Voltage conversion is realized by turning ON / OFF the switching element Q1 or Q2 provided in the first or second loop circuit. At this time, the first and second capacitors have functions of smoothing the output voltage of the DC-DC converter and reducing noise generated by the DC-DC converter circuit. Such a circuit configuration shown in FIG. 1 is generally realized by arranging the first loop circuit and the second loop circuit side by side on the same surface or different surfaces on the printed board as shown in FIG. The

  However, in the conventional circuit configuration shown in FIGS. 1 and 2, for example, when the switching element Q1 is turned ON / OFF, current flows alternately in the first loop circuit and the second loop circuit. A magnetic field penetrating the circuit and a magnetic field penetrating the second loop circuit are alternately generated. At this time, since the directions of the currents flowing through the first loop circuit and the second loop circuit are opposite to each other as shown by the arrows in FIG. 1, the magnetic field passing through the first loop circuit and the magnetic field passing through the second loop circuit. The direction of is opposite. In such a configuration, a magnetic field having a reverse direction is alternately generated at a high speed (short time) in accordance with a high-speed (short time) ON / OFF operation of the switching element Q1, and noise due to the fluctuation of the magnetic field is generated. There's a problem.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a voltage converter that can effectively reduce noise caused by magnetic field fluctuations formed in the first loop circuit and the second loop circuit, and an electric load driving device using the voltage converter. To do.

To achieve the above object, according to one aspect of the present invention, a first loop circuit and a second loop circuit sharing an inductance element are provided, and ON / OFF of a first switching element provided in the first loop circuit is provided. A voltage conversion device in which current flows alternately in the first loop circuit and the second loop circuit in operation,
The direction of the magnetic field penetrating through the first loop circuit formed when the switching element of the first loop circuit is turned on, and the first time formed when the first switching element of the first loop circuit is turned off after the ON operation of the first loop circuit. The direction of the magnetic field passing through the two-loop circuit is the same direction,
An area of an overlapping portion of the first and second loop circuits is equal to or larger than an area of a non-overlapping portion.

According to another aspect of the present invention, a first loop circuit and a second loop circuit that share an inductance component and have first and second switching elements, and first and second capacitive elements, respectively. A voltage conversion device in which a current flows alternately to the first loop circuit and the second loop circuit in accordance with an ON / OFF operation of a first switching element provided in the first loop circuit,
A first DC power source or a ground is connected to a midpoint between the first switching element and the first capacitive element in the first loop circuit, and the second switching element and the second capacitive element in the second loop circuit. Is connected to a second DC power supply having a voltage different from that of the first DC power supply,
The first loop circuit and the second loop circuit are arranged so that one of the first loop circuit and the second loop circuit surrounds the other,
An area of an overlapping portion of the first and second loop circuits is equal to or larger than an area of a non-overlapping portion of the first and second loop circuits.

  ADVANTAGE OF THE INVENTION According to this invention, the voltage converter etc. which can reduce effectively the noise resulting from the magnetic field variation formed in a 1st loop circuit and a 2nd loop circuit are obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 3 is a diagram showing a circuit configuration of an embodiment of the voltage converter 1 according to the present invention. The voltage converter 1 according to the present invention is configured by arranging the circuit configuration of the voltage converter 1 as shown in FIG.

  The voltage conversion apparatus 1 according to this embodiment is a synchronous rectification type non-insulated DC / DC converter, and includes a first loop circuit 10 and a second loop circuit 12. An electric load 40 to be driven is connected to the output terminal 20 of the voltage conversion device 1. The first loop circuit 10 and the second loop circuit 12 share the inductance L. In the illustrated example, the first loop circuit 10 is arranged so as to surround the second loop circuit 12.

  The first loop circuit 10 includes a switching element Q1 and a capacitor C1 in addition to the inductance L. In this example, the switching element Q1 is a MOSFET (metal oxide semiconductor field-effect transistor), but may be another transistor such as an IGBT (Insulated Gate Bipolar Transistor). The switching element Q <b> 1 is connected in series with the inductance L between the + terminal and the output terminal 20. At this time, when an Nch-MOSFET is used as the switching element Q1, the switching element Q1 has the drain side connected to the + terminal and the source side connected to the inductance L. On the other hand, when a Pch-MOSFET is used as the switching element Q1, the switching element Q1 has a source side connected to the + terminal and a drain side connected to the inductance L. The capacitor C1 is connected in parallel with the switching element Q1 and the inductance L between the + terminal and the output terminal 20.

  Similarly, in addition to the inductance L, the second loop circuit 12 has a switching element Q2 and a capacitor C2. The switching element Q1 is a MOSFET in this example, but may be another transistor such as an IGBT. The switching element Q <b> 2 is connected in series with the inductance L between the − terminal and the output terminal 20. At this time, when an Nch-MOSFET is used as the switching element Q2, the switching element Q2 has a drain side connected to the inductance L and a source side connected to the-terminal. On the other hand, when a Pch-MOSFET is used as the switching element Q2, the switching element Q2 has a source side connected to the inductance L and a drain side connected to the-terminal. The capacitor C <b> 2 is connected in parallel with the switching element Q <b> 2 and the inductance L between the − terminal and the output terminal 20.

  A first DC power supply (see DC power supply 203 in FIG. 15) is connected to the + terminal, and a second DC power supply (not shown) having a voltage lower than that of the first DC power supply is connected to the − terminal. Is done. The rated voltages of the first DC power source and the second DC power source may be arbitrary as long as the second DC power source is lower than the first DC power source. Typically, a ground (that is, OV) is connected to the-terminal. In the following, in order to prevent complication of explanation, it is assumed that the − terminal is connected to the ground unless otherwise specified.

  The capacitor C1 and the capacitor C2 mainly have a function of smoothing the output voltage of the voltage conversion device 1 and reducing noise generated in the voltage conversion device 1. The capacities of the capacitor C1 and the capacitor C2 are preferably set to be the same. In addition, as the capacitor C1 and the capacitor C2, a ceramic type capacitor that does not easily deteriorate in durability is preferably used in order to reduce the influence of deterioration.

  The switching elements Q1 and Q2 are controlled so that when one is ON, the other is OFF. The details of the control mode of the switching elements Q1 and Q2 (for example, the setting / adjustment method of the dead time) are arbitrary.

  The voltage conversion apparatus 1 of the present embodiment is configured such that the directions of loop currents flowing through the second loop circuit 12 and the first loop circuit 10 are the same. That is, as apparent from the comparison between the voltage converter 1 of the present embodiment and the conventional configuration shown in FIGS. 1 and 2, the voltage converter 1 of the present embodiment has the conventional configuration shown in FIG. It is the structure which turned up along line XX shown in FIG. Thereby, in contrast to the conventional configuration shown in FIG. 1, the directions of the loop currents flowing in the second loop circuit 12 and the first loop circuit 10 are the same during the operation of the voltage conversion device 1.

  In the example shown in FIG. 3, when the switching element Q2 is turned on during operation, the switching element Q1 is turned off in synchronization with the switching element Q2, and the second loop circuit 12 is indicated by an arrow in the figure as shown in FIG. The current I2 flows through the loop in the direction. When the switching element Q2 is inverted from on to off, the switching element Q1 is inverted from off to on in synchronization with it, and as shown in FIG. 4B, the first loop circuit 10 has a direction indicated by an arrow in the figure. A current I1 flows in the loop. In this way, by appropriately controlling the time during which the switching element Q2 is on (on duty), the voltage of the first DC power supply is converted into a desired voltage (step-down conversion), and the output terminal 20 Can be output.

  In the example shown in FIG. 3, since the + terminal is connected to the other end of the electrical load 40 (a terminal that is not on the output terminal 20 side), the ON / OFF operation of the switching element Q2 substantially determines the duty, The switching element Q1 functions as a synchronous rectification switching element. For example, when cost is given priority over energy efficiency, the switching element Q1 may be omitted (only a diode is provided). For example, as illustrated in FIG. 5, a negative terminal may be connected to the other end of the electrical load 40 (a terminal that is not on the output terminal 20 side). In this case, contrary to the example shown in FIG. 3, the ON / OFF operation of the switching element Q1 substantially determines the duty, and the switching element Q2 functions as a synchronous rectification switching element. In the example shown in FIG. 5 as well, for example, when cost is given priority over energy efficiency, the switching element Q2 may be omitted (only a diode is provided).

  By the way, as described above with reference to FIG. 2, if the circuit configuration of the voltage conversion device as shown in FIG. 1 is arranged as it is, the first loop is used when the switching element Q2 is turned on and off at high speed. A magnetic field penetrating the circuit and a reverse magnetic field penetrating the second loop circuit are alternately generated at a high speed, resulting in a problem that high-frequency noise is generated due to high-frequency fluctuations of the magnetic field.

  On the other hand, according to the voltage conversion device 1 of the present embodiment, as shown in FIGS. 4A and 4B, when the switching element Q2 is turned ON / OFF at high speed, the current I1 The direction of the current I2 is the same as the direction of the current I2, and a magnetic field passing through the first loop circuit and a magnetic field in the same direction passing through the second loop circuit are alternately generated at high speed, so that the first loop circuit 10 and the second loop In the overlapping portion 80 (see FIG. 7) of the circuit 12, high frequency noise caused by high frequency fluctuation of the magnetic field can be reduced.

  FIG. 6 is a waveform diagram for explaining the principle of the magnetic flux fluctuation reduction effect of the above-described embodiment.

  As described above, when the switching elements Q2 and Q1 are driven with a predetermined duty inverted from each other, the second loop circuit 12 and the first loop circuit have waveforms as shown in FIGS. 6 (A) and 6 (B). A current flows through 10. At this time, the magnetic flux penetrating the second loop circuit 12 in a waveform (time series) as shown in FIGS. 6C and 6B due to the current flowing through the second loop circuit 12 and the first loop circuit 10. A magnetic flux φ1 penetrating φ2 and the first loop circuit 10 is generated. Such magnetic fluxes φ2 and φ1 vary greatly in a short time because the switching elements Q2 and Q1 are driven at high speed. In this embodiment, as described above, the directions of the loop currents flowing in the second loop circuit 12 and the first loop circuit 10 are the same, and the magnetic flux φ2 and the magnetic flux φ1 shown in FIGS. 6C and 6B are in the same direction. Therefore, when these waveforms (time series) are added together, a waveform having no steep fluctuation as shown in FIG. 6E is obtained. That is, a magnetic flux change with little temporal variation is realized in the overlapping portion 80 (see FIG. 7) of the first loop circuit 10 and the second loop circuit 12. Thus, according to the voltage converter 1 of the present embodiment, it is possible to effectively reduce noise generated due to high-frequency fluctuations of the magnetic flux φ1 + φ2.

  Next, a configuration for efficiently obtaining the noise reduction effect (see FIG. 6) of the present embodiment as described above will be described. Here, a configuration for efficiently obtaining a noise reduction effect will be described from two approaches.

  In the first approach, the area of the overlapping portion of the first loop circuit 10 and the second loop circuit 12 is set to be larger than the area of the non-overlapping portion (non-overlapping portion) of the first loop circuit 10 and the second loop circuit 12. It is. In addition, an area is an area (area through which magnetic flux penetrates) when viewed along the direction through which magnetic flux penetrates.

  FIG. 7 is an explanatory diagram of the first approach. In FIG. 7, the overlapping portion of the first loop circuit 10 and the second loop circuit 12 is indicated by hatching with reference numeral 80, and the non-overlapping portion (non-overlapping portion) of the first loop circuit 10 and the second loop circuit 12. ) Is indicated by hatching with reference numeral 82. Therefore, in the first approach, the area S1 ′ of the overlapping portion 80 of the first loop circuit 10 and the second loop circuit 12 is larger than the area S2 of the non-overlapping portion 82 of the first loop circuit 10 and the second loop circuit 12. Is set to be

Here, the magnetic field and permeability of the overlapping portion 80 are H1 and μ1, respectively, and the magnetic field and permeability of the non-overlapping portion 82 are H2 and μ1, respectively. Magnetic fields H1 and H2 are generated in respective portions by currents I1 and I2 (see FIG. 4). At this time, the magnetic flux Φ1 generated when the current I1 flows is as follows.
Φ1 = ∫B1 ・ S = k1 ・ μ1 (H1 ・ S1 ′ + H2 ・ S2) ・ I1
Similarly, the magnetic flux Φ2 generated when the current I2 flows is as follows.
Φ2 = ∫B2, S = k2, μ1, H1, S1 ′, I2
From this, since k1 · I1≈k2 · I2, it can be seen that by setting S1 ′ >> S2, Φ1≈Φ2, and steep magnetic flux fluctuations can be suppressed. Although depending on actual dimensions and the like, it is desirable that the area of the first loop circuit 10 and the area of the second loop circuit 12 are as small as possible.

  The second approach is to place a magnetic member in the overlapping portion 80 of the first loop circuit 10 and the second loop circuit 12. Needless to say, this second approach can be combined with the first approach described above, and in this case, an effect obtained by adding the respective effects can be obtained.

  8 and 9 are explanatory diagrams of the second approach. In the example illustrated in FIG. 8, the magnetic members 90 and 92 are disposed in the overlapping portion 80 of the first loop circuit 10 and the second loop circuit 12. The magnetic member may be a member provided only for this purpose, but is preferably a member provided also for other purposes. In the example shown in FIG. 8, the magnetic member 90 is a board mounting screw or a positioning pin. That is, the magnetic member 90 includes a metal fastener such as a screw used when the substrate on which the first loop circuit 10 and the second loop circuit 12 are formed is attached to the casing constituent member (member constituting the casing). This is a positioning pin. The magnetic member 92 is a heat radiating plate for cooling the switching element Q2. The magnetic member 92 may be a heat radiating plate that cools the switching element Q1 together with the switching element Q2, or may be a heat radiating plate that cools the switching element Q1 instead of the switching element Q2.

In FIG. 9, a portion of the overlapping portion 80 where the magnetic material is disposed (hereinafter referred to as “magnetic portion”) is indicated by hatching with reference numeral 84. Here, the magnetic field and permeability of the overlapping portion 80 are H1 and μ1, respectively, the magnetic field and permeability of the non-overlapping portion 82 are H2 and μ1, respectively, and the area, magnetic field, and permeability of the magnetic portion 84 are S3 and H3, respectively. And μ2. Further, the area excluding the magnetic part 84 of the overlapping part 80 is defined as S1. At this time, the magnetic flux Φ1 generated when the current I1 flows is as follows.
Φ1 = ∫B1 · S = k1 · {μ1 · (H1 · S1 + H2 · S2) + μ2 · H3 · S3} · I1
Similarly, the magnetic flux Φ2 generated when the current I2 flows is as follows.
Φ2 = ∫B2, S = k2, {μ1, H1, S1 + μ2, H3, S3}, I2
From this, since k1 · I1≈k2 · I2, it can be seen that by setting S1 (or S1 + S3) >> S2, Φ1≈Φ2, and steep magnetic flux fluctuations can be suppressed. Further, since the magnetic permeability of the magnetic member 90 is preferably 500 or more and high, even if S2 is large to some extent, a relationship of Φ1≈Φ2 can be formed.

  10 to 13 are diagrams showing test results for confirming the noise reduction effect by the above-described first approach. FIG. 10 is a circuit board configuration prototyped corresponding to the voltage converter 1 of the present embodiment as shown in FIG. 3, and the area S1 ′ of the overlapping portion 80 is substantially the same as the area S2 of the non-overlapping portion 82. FIG. 10A shows the configuration of the front surface of the printed circuit board, and FIG. 10B shows the configuration of the back surface of the printed circuit board. Further, FIG. 11 shows a substrate configuration prototyped corresponding to the voltage converter 1 of the present embodiment as shown in FIG. 3, where the area S1 ′ of the overlapping portion 80 is larger than the area S2 of the non-overlapping portion 82. FIG. 11A shows the configuration of the surface of the printed circuit board, and FIG. 11B shows the configuration of the surface of the printed circuit board. These show the structure of the back surface of a printed circuit board. Moreover, FIG. 12 shows the board | substrate structure produced as a test corresponding to the conventional voltage converter as shown in FIG. 1 as a reference example, FIG. 12 (A) shows the structure of the surface of a printed circuit board, FIG. 12B shows the configuration of the back surface of the printed board. 10 to 12, each part indicated by hatching 73 is associated with a circuit portion of the power supply system (+ terminal side, + B system in this example), and hatched by reference numeral 71. Each part shown corresponds to a circuit part of the output part, and each part shown by hatching with reference numeral 72 corresponds to a circuit part of the ground system (-terminal side).

  FIG. 13 shows noise waveforms measured by actually operating the devices shown in FIGS. In FIG. 13, the noise characteristics by the voltage converter 1 of the present embodiment are indicated by solid lines A1 and A2, and the noise characteristics by the conventional configuration are indicated by dotted lines. As can be seen from FIG. 13, according to the present embodiment, the noise level is significantly reduced as compared with the noise characteristics of the conventional configuration. Further, even when the area S1 ′ of the overlapping portion 80 is substantially the same as the area S2 of the non-overlapping portion 82, as shown by the solid line A1, the noise level is greatly reduced as compared with the noise characteristics of the conventional configuration. You can see that When the area S1 ′ of the overlapping portion 80 is significantly larger than the area S2 of the non-overlapping portion 82, the area S1 ′ of the overlapping portion 80 is substantially the same as the area S2 of the non-overlapping portion 82, as shown by the solid line A2. It can be seen that the noise level is further reduced as compared with the case of.

  Therefore, in this embodiment, it is desirable that the area S1 ′ of the overlapping portion 80 is larger than the area S2 of the non-overlapping portion 82, and more preferably, the area S1 ′ of the overlapping portion 80 is the area S2 of the non-overlapping portion 82. The area S1 ′ of the overlapping portion 80 is more preferably 10 times or more than the area S2 of the non-overlapping portion 82.

  FIG. 14 is a diagram showing test results for confirming the noise reduction effect by the above-described second approach (magnetic material arrangement). In FIG. 14, the result when the magnetic material is not arranged in the overlapping portion 80 in the substrate configuration shown in FIG. 11 is indicated by a curve A2, and the magnetic material is arranged in the overlapping portion 80 in the substrate configuration shown in FIG. The result is shown by curve A3. From FIG. 14, it can be seen that the noise level is further reduced by disposing the magnetic body in the overlapping portion 80 of the first loop circuit 10 and the second loop circuit 12 as compared with the case where the magnetic body is not disposed.

  FIG. 15 is a block diagram showing an embodiment of the electric load driving device 200 according to the present invention.

  The electric load driving device 200 of this embodiment includes an electric load driving circuit device 201, a control target signal generator (PCM) 202, and a DC power source 203. The electrical load drive circuit device 201 includes the voltage conversion device 1 described above, and also includes an internal power supply circuit 101, an input signal interface circuit 102, a switching duty generation circuit 103, and a switching element drive circuit 104. The terminals T1 and T4 correspond to the above-described + terminal, the terminal T3 corresponds to the-terminal, and T5 corresponds to the output terminal 20 of the voltage conversion device 1. Instead of the voltage converter 1, voltage converters 2 and 3 according to other examples described later may be used.

  In the example shown in FIG. 15, the electrical load 40 is an inductive load, and is a fuel pump used for a vehicle engine. However, the electric load 40 may be an arbitrary electric load such as a fan or a steering assist motor. The switch indicated by reference sign S1 corresponds to an ignition switch.

  The control target signal generator 202 is constituted by a microcomputer, and may be, for example, an EFI • ECU that controls a vehicle engine. The control target signal generator 202 determines a control target value (for example, target rotational speed) of the fuel pump, and inputs a control target signal representing the control target value to the electric load drive circuit device 201. The control target signal generator 202 operates based on the power supply voltage from the DC power supply 203, but may include a step-down circuit or the like inside.

  The control target signal from the control target signal generator 202 is processed by the input signal interface circuit 102 of the control target signal generator 202, and the duty for realizing the control target value is determined by the switching duty generation circuit 103. The switching elements Q1 and Q2 are ON / OFF controlled by the switching element drive circuit 104 in accordance with the determined duty.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in the above-described embodiment, a specific example of a configuration in which currents in the same direction flow in the first loop circuit 10 and the second loop circuit 12 during operation of the voltage conversion device 1 is disclosed. Not limited. For example, as shown in FIG. 16, an equivalent change may be added to the configuration shown in FIG. In the configuration shown in FIG. 3 and the like, the second loop circuit 12 is surrounded by the first loop circuit 10, but conversely, the first loop circuit 10 is surrounded by the second loop circuit 12. It may be. Alternatively, in the configuration shown in FIG. 3, the length of the common portion occupies a ratio larger than at least 1/2 of the entire loop length, and occupies a ratio of about 2/3 to 3/4. As shown in FIG. 5, the ratio of the length of the common portion to the entire length of the loop may be reduced to be smaller than ½. Even in such a configuration, since the first loop circuit 10 surrounds the second loop circuit 12, a further noise reduction effect can be achieved by the above-described first and / or second approaches.

  In the above-described embodiment, the first loop circuit 10 and the constituent elements (mainly elements) of the second loop circuit 12 are formed on the same substrate surface for the purpose of improving the immunity performance. However, one or a part of the first loop circuit 10 or the second loop circuit 12 may be formed on the back surface of the same substrate, or may be formed on another stacked substrate.

  In the above-described embodiments, the step-down voltage converter is used, but it may be applied to a step-up or bidirectional voltage converter.

It is a figure which shows the circuit structure of the conventional DC-DC converter. It is a figure which shows the components arrangement | positioning of the conventional DC-DC converter. It is a figure which shows the circuit structure of the voltage converter 1 which concerns on one Example by this invention. FIG. 4 is a diagram illustrating directions of loop currents I2 and I1 flowing in the second loop circuit 12 and the first loop circuit 10, respectively. It is a figure which shows the other example of the connection method of the electrical load. It is a wave form diagram explaining the principle of the magnetic flux fluctuation reduction effect in the voltage converter 1 of a present Example. It is explanatory drawing of the preferable 1st approach for suppressing a steep magnetic flux fluctuation | variation. It is explanatory drawing of the preferable 2nd approach for suppressing steep magnetic flux fluctuation | variation. It is explanatory drawing of the 2nd approach. It is a figure which shows the board | substrate structure made as an experiment corresponding to the voltage converter 1 of a present Example. It is a figure which shows the board | substrate structure made as an experiment corresponding to the voltage converter 1 of a present Example. It is a figure which shows the board | substrate structure prototyped as a conventional voltage converter. FIG. 13 is a diagram showing noise waveforms measured by actually operating the devices shown in FIGS. 10 to 12, respectively. It is a figure which shows the test result which confirmed the noise reduction effect by a 2nd approach. It is a block diagram which shows one Example of the electrical load drive device 200 by this invention. It is a figure which shows the circuit structure of the voltage converter 2 which concerns on another one Example. It is a figure which shows the circuit structure of the voltage converter 3 which concerns on another one Example.

Explanation of symbols

L Inductance C1 Capacitor C2 Capacitor Q1 Switching element Q2 Switching element 1, 2, 3 Voltage converter 10 First loop circuit 12 Second loop circuit 40 Electric load 80 Overlapping portion 82 Non-overlapping portion 84 Magnetic body portion 90 Magnetic body member 92 Magnetic Body member 203 DC power supply

Claims (10)

A first loop circuit and a second loop circuit sharing an inductance element are provided, and the first loop circuit and the second loop circuit are alternately switched in accordance with an ON / OFF operation of the first switching element provided in the first loop circuit. A voltage conversion device in which a current flows in
The direction of the magnetic field penetrating through the first loop circuit formed when the switching element of the first loop circuit is turned on, and the first time formed when the first switching element of the first loop circuit is turned off after the ON operation of the first loop circuit. The direction of the magnetic field passing through the two-loop circuit is the same direction,
The voltage converter according to claim 1, wherein an area of an overlapping portion of the first and second loop circuits is equal to or larger than an area of an overlapping portion of the first and second loop circuits. The first and second loop circuits are formed on a common substrate;
The voltage converter according to claim 1, wherein a magnetic body is disposed in an overlapping portion of the first and second loop circuits on the substrate. The first and second loop circuits are formed on a common substrate;
3. The voltage conversion device according to claim 1, wherein a metal fastening member for attaching the substrate to the casing constituent member is disposed in an overlapping portion of the first and second loop circuits in the substrate. The first and second loop circuits are formed on a common substrate;
The metal member for cooling the said 1st switching element is arrange | positioned in the overlap part of the said 1st and 2nd loop circuit in the said board | substrate, Any one of Claims 1-3. Voltage converter. A second switching element is provided in the second loop circuit;
5. The voltage conversion device according to claim 1, wherein the first and second switching elements are controlled such that one of them is turned OFF in synchronization with the one of them being turned ON. The first and second loop circuits are formed on a common substrate;
The voltage conversion device according to claim 5, wherein a metal member for cooling the second switching element is disposed in an overlapping portion of the first and second loop circuits on the substrate.   The voltage conversion apparatus according to claim 1, wherein the first and second loop circuits are provided with first and second capacitive elements, respectively. A first switching circuit provided in the first loop circuit, the first loop circuit including a first loop circuit and a second loop circuit each having an inductance component and having first and second switching elements and first and second capacitive elements, respectively. A voltage conversion device in which current flows alternately in the first loop circuit and the second loop circuit in accordance with ON / OFF operation of an element,
A first DC power source or a ground is connected to a midpoint between the first switching element and the first capacitive element in the first loop circuit, and the second switching element and the second capacitive element in the second loop circuit. Is connected to a second DC power supply having a voltage different from that of the first DC power supply,
The first loop circuit and the second loop circuit are arranged so that one of the first loop circuit and the second loop circuit surrounds the other,
The voltage converter according to claim 1, wherein an area of an overlapping portion of the first and second loop circuits is equal to or larger than an area of an overlapping portion of the first and second loop circuits. A first loop circuit and a second loop circuit sharing an inductance element are provided, and the first loop circuit and the second loop circuit are alternately switched in accordance with an ON / OFF operation of the first switching element provided in the first loop circuit. A voltage conversion device in which a current flows in
The direction of the magnetic field penetrating through the first loop circuit formed when the switching element of the first loop circuit is turned on, and the first time formed when the first switching element of the first loop circuit is turned off after the ON operation of the first loop circuit. The direction of the magnetic field passing through the two-loop circuit is the same direction,
A voltage converter, wherein a magnetic material is disposed in an overlapping portion of the first and second loop circuits. An electric load driving device for driving an electric load,
DC power supply,
The voltage converter according to any one of claims 1 to 9, wherein the voltage level of a DC power source received from the DC power source is converted and output to the electric load.
And a control device for controlling the voltage conversion device.