Control device for a power conversion device

Abstract

A control device of a power conversion device using a three-phase magnetic coupled reactor capable of reducing loss at single-phase operation is provided. A first outer core portion (21) and a second outer core portion (23) each have an outer gap (26, 28) at the center in a first direction, and an inner core portion (22) has an inner gap (27) in the first direction having a length greater than the outer gaps (26, 28) in the first direction at the center in the first direction, thereby balancing the inductance of the three phases, and reducing ripple current and loss at three-phase operation of selecting the outer coils (11, 13) and the inner coil (12). Also, at single-phase operation of selecting any one of the coils (11) to (13), by selecting the inner coil (12) having a large inductance, ripple current and loss are reduced.

Description

Technical Field

[0001] This invention relates to a control device for a power conversion device. Background Technology

[0002] In recent years, research and development efforts have been made to improve energy efficiency in order to ensure that more people have access to suitable, reliable, sustainable and advanced energy.

[0003] In DC-DC converters used in electric vehicles and HEVs (Hybrid Electrical Vehicles), reactors are constructed by mounting coils around an iron core. In recent years, high-output converters have employed multiphase converters aimed at maximizing efficiency by setting multiple drive phases and dividing the current. In such multiphase converters, losses are known to vary depending on the number of operating phases; therefore, control methods are generally employed to reduce switching losses at low outputs by decreasing the number of operating phases.

[0004] For example, Patent Document 1 proposes to create a loss diagram centered on current and operate with the most efficient number of phases.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-153240 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] Patent Document 1 describes a DC-DC converter that utilizes a four-phase reactor with two two-phase cores integrated into a magnetically coupled reactor, instead of a three-phase core integrated into a three-phase magnetically coupled reactor. In a three-phase magnetically coupled reactor, to reduce switching losses at low currents, it is preferable to have a smaller number of operating phases.

[0010] When using a three-phase magnetically coupled reactor for single-phase operation, there is room for research on which phase can reduce losses.

[0011] The present invention provides a control device for a power conversion device, which uses a three-phase magnetically coupled reactor that can reduce losses during single-phase operation.

[0012] Solution for solving the problem

[0013] This invention provides a control device for a power conversion device, which uses a three-phase magnetically coupled reactor, wherein...

[0014] The three-phase magnetically coupled reactor includes:

[0015] First outer coil;

[0016] Second outer coil;

[0017] The inner coil is disposed between the first outer coil and the second outer coil; and

[0018] The iron core includes a first outer iron core portion wound around the first outer coil, a second outer iron core portion wound around the second outer coil, and an inner iron core portion wound around the inner coil.

[0019] The first outer core portion, the second outer core portion, and the inner core portion extend in a first direction and are arranged in a second direction orthogonal to the first direction.

[0020] The first outer core portion, the second outer core portion, and the inner core portion are connected at one end in the first direction by a first connecting portion extending in the second direction.

[0021] The first outer core portion, the second outer core portion, and the inner core portion are connected at their other ends in the first direction by a second connecting portion extending in the second direction.

[0022] The magnetic flux of the first outer core, the second outer core, and the inner core is configured such that the direction of the DC magnetic flux generated in the core due to other coils wound in other cores is opposite to the direction of the DC magnetic flux generated in the core due to the coils wound in any core.

[0023] The first outer core portion and the second outer core portion each have an outer gap at the center in the first direction.

[0024] The inner core portion has an inner gap at its center in the first direction, the length of which is greater than that of the outer gap in the first direction.

[0025] The control device can switch between single-phase operation, two-phase operation, and three-phase operation.

[0026] The single-phase operation is achieved by allowing current to flow through any one of the first outer coil, the second outer coil, and the inner coil.

[0027] The two-phase operation is achieved by allowing current to flow through any two of the following coils: the first outer coil, the second outer coil, and the inner coil.

[0028] The three-phase operation is achieved by allowing current to flow through all the coils of the first outer coil, the second outer coil, and the inner coil.

[0029] In the single-phase operation, the inner coil is selected.

[0030] Invention Effects

[0031] According to the present invention, in a power conversion device using a three-phase magnetically coupled reactor, losses during single-phase operation can be reduced. Attached Figure Description

[0032] Figure 1 This is the circuit diagram of a three-phase interleaved DC-DC converter 10.

[0033] Figure 2 This is a perspective view of the three-phase magnetically coupled reactor 1 used in the DC-DC converter 10.

[0034] Figure 3 This is a plan view of the three-phase magnetically coupled reactor 1.

[0035] Figure 4 It is a diagram showing the orientation of the magnetic flux in each core section during the operation of phases 2 and 3.

[0036] Figure 5 It is a diagram showing the orientation of the magnetic flux in each core section during the operation of phases 1 and 3.

[0037] Figure 6 This is a diagram used to illustrate gaps 26 to 28.

[0038] Figure 7 This is a diagram used to illustrate the leakage flux of core 20.

[0039] Figure 8 This is a graph showing the relationship between magnetic flux density B, magnetic field strength H, and permeability μ.

[0040] Figure 9 This indicates the length t of the gap, which is 26 to 28. o t i A graph showing the relationship between inductance and inductance.

[0041] Figure 10 This is a graph showing the current correlation of ripple during three-phase operation.

[0042] Figure 11 This is a diagram showing the relationship between the current and inductance of coils 11 to 13.

[0043] Explanation of reference numerals in the attached figures:

[0044] 1 Three-phase magnetically coupled reactor

[0045] 10. DC-DC converter (power conversion device)

[0046] 11 First outer coil

[0047] 12 Inner Coils

[0048] 13 Second outer coil

[0049] 20 Iron Heart

[0050] 21 First outer core section

[0051] 22 Inner core section

[0052] 23 Second outer core section

[0053] 24 First connecting section

[0054] 25 Second connecting section

[0055] 26. Outer gap

[0056] 27. Inner gap

[0057] 28. Outer gap

[0058] CTR control device Detailed Implementation

[0059] Hereinafter, the control device of a power conversion device according to one embodiment of the present invention will be described with reference to the accompanying drawings.

[0060] First, a three-phase interleaved DC-DC converter, which is an example of a power conversion device and the controlled object of the control device of the present invention, will be described. Figure 1 This is a circuit diagram representing a three-phase interleaved DC-DC converter.

[0061] Figure 1 The three-phase interleaved DC-DC converter 10 shown (hereinafter referred to as DC-DC converter 10) includes a smoothing capacitor C1, a three-phase magnetically coupled reactor 1 (hereinafter referred to as three-phase reactor) having three coils 11 to 13, switching units SW1, SW2, SW3, diodes D1, D2, D3, smoothing capacitor C2, and control device CTR.

[0062] The DC-DC converter 10 boosts the input voltage V1 when operating with the voltage V1 on the side of the smoothing capacitor C1 as the input voltage and the voltage V2 on the side of the smoothing capacitor C2 as the output voltage.

[0063] The input terminals of coils 11 to 13 of the three-phase reactor 1 are connected in parallel with the power supply line on the high-potential side. The output terminal of coil 11 of the three-phase reactor 1 is connected to the intermediate node of the series-connected switch section SW1 and diode D1, forming the first voltage conversion section 14. The output terminal of coil 12 of the three-phase reactor 1 is connected to the intermediate node of the series-connected switch section SW2 and diode D2, forming the second voltage conversion section 15. The output terminal of coil 13 of the three-phase reactor 1 is connected to the intermediate node of the series-connected switch section SW3 and diode D3, forming the third voltage conversion section 16. Switch sections SW1, SW2, and SW3 each have a switching element such as an IGBT (Insulated Gate Bipolar Transistor) and a return diode connected in parallel with the switching element.

[0064] Furthermore, in the three-phase reactor 1, "three-phase" refers to the number of switching units being three. The term "single-phase operation" (described later) refers to one switching unit among the first voltage switching units 14 to the third voltage switching units 16; "two-phase operation" refers to two switching units; and "three-phase operation" refers to three switching units. In the following description, the first voltage switching unit 14 is sometimes referred to as "phase 1," the second voltage switching unit 15 as "phase 2," and the third voltage switching unit 16 as "phase 3."

[0065] Each switching element of the switching sections SW1 to SW3 is controlled to be switched on and off by a signal from the control device CTR. The DC-DC converter 10 has three voltage conversion sections 14, 15, and 16 connected in parallel. By switching at least one of the switching elements of the voltage conversion sections 14, 15, and 16 on and off at a desired timing, the voltage V1 is boosted and the output voltage V2 is produced while maintaining DC power. The switching operation of the switching sections SW1, SW2, and SW3 of the voltage conversion sections 14, 15, and 16 is controlled by a pulse-shaped switching signal with a predetermined duty cycle sent from the switching control unit to the DC-DC converter 10.

[0066] When switching elements of voltage conversion sections 14, 15, and 16 are switched on and off, during the on-state operation, the input current to the DC-DC converter 10 flows to the switching element side, and the three-phase reactor 1 stores energy. During the off-state operation, the input current to the DC-DC converter 10 flows to the diode side, and the three-phase reactor 1 releases the stored energy. In the case of single-phase operation where only one of the three voltage conversion sections 14, 15, and 16 of the DC-DC converter 10 is driven, the output current flows through the voltage conversion section of the DC-DC converter 10 during the off-state operation. Furthermore, in the case of two-phase operation where two of the three voltage conversion sections 14, 15, and 16 of the DC-DC converter 10 are driven, for example, interleaved control is performed where the on-state switching phases of each voltage conversion section 14, 15, and 16 to be driven are staggered by 180 degrees. In the case of three-phase operation in which all three voltage conversion sections 14, 15, and 16 of the DC-DC converter 10 are driven, for example, interleaved control is performed in which the on / off switching phases of each voltage conversion section 14, 15, and 16 are staggered by 120 degrees.

[0067] Next, the structure of the three-phase reactor 1 will be described. In the following description, the outermost coils 11 and 13 of the three coils 11 to 13 will be referred to as the first outer coil 11 and the second outer coil 13, respectively, and the coil 12 sandwiched between the first outer coil 11 and the second outer coil 13 will be referred to as the inner coil 12. Furthermore, as... Figure 2 and Figure 3 As shown, the positional relationships of various parts of the three-phase reactor 1 are explained using an orthogonal coordinate system of X-axis, Y-axis, and Z-axis.

[0068] like Figure 2 As shown, the three-phase reactor 1 includes a first outer coil 11, a second outer coil 13, an inner coil 12, an iron core 20, and a housing 40 for housing the above components.

[0069] The iron core 20, for example, is composed of a pressed powder core formed by molding powder of soft magnets. Figure 3 As shown, the core 20 includes: a first outer core portion 21, an inner core portion 22, and a second outer core portion 23, which extend in the X-axis direction and are arranged parallel to each other along the Y-axis direction; a first connecting portion 24, which extends in the Y-axis direction at one end in the X-axis direction and connects the first outer core portion 21, the inner core portion 22, and the second outer core portion 23; and a second connecting portion 25, which extends in the Y-axis direction at the other end in the X-axis direction and connects the first outer core portion 21, the inner core portion 22, and the second outer core portion 23. In other words, the core 20 is a planar core disposed on an XY plane formed along the X-axis and Y-axis directions. The X-axis direction is the first direction of the present invention, and the Y-axis direction is the second direction of the present invention.

[0070] The first outer core portion 21 and the second outer core portion 23 have gaps 26 and 28 (hereinafter referred to as outer gaps 26 and 28) at their centers in the X direction, respectively. In addition, the inner core portion 22 has a gap 27 (hereinafter referred to as inner gap 27) at its center in the X direction. These gaps 26 to 28 are provided for adjusting the magnetic reluctance of each phase, as will be described in detail later.

[0071] A first outer coil 11 is wound on the first outer core portion 21, a second outer coil 13 is wound on the second outer core portion 23, and an inner coil 12 is wound on the inner core portion 22. Therefore, the first outer core portion 21, the inner core portion 22, and the second outer core portion 23 extend in the X-axis direction and are arranged in the Y-axis direction. The number of turns and the winding direction of each coil 11 to 13 are identical.

[0072] In this three-phase reactor 1, when current flows through any two or more of the coils 11, 12, and 13, in any combination, the directions of the magnetic flux generated in each coil (hereinafter referred to as the magnetic flux direction) are opposite to each other, which can reduce the magnetic flux generated in the core. That is, the magnetic flux configuration of the first outer core 21, the second outer core 23, and the inner core 22 is such that the direction of the DC magnetic flux generated in the core due to the coils wound around any core is opposite to the direction of the DC magnetic flux generated in the core due to the other coils wound around the other cores. As a result, magnetic saturation of the core 20 can be suppressed, and a larger inductance can be generated.

[0073] Taking two-phase motion as an example, using Figure 4 and Figure 5 A more specific explanation of the flow of magnetic flux is given.

[0074] Figure 4 This is a diagram showing the orientation of the magnetic flux in each core section during the operation of phases 2 and 3. Figure 5 This is a diagram showing the orientation of the magnetic flux in each core section during the operation of phases 1 and 3. In the following explanation, as... Figure 4 and Figure 5 As shown, the orientation above the paper in the X direction is set as +X direction, the orientation below the paper in the X direction is set as -X direction, the orientation to the right of the paper in the Y direction is set as +Y direction, and the orientation to the left of the paper in the Y direction is set as -Y direction.

[0075] like Figure 4As shown, when phase 2 and phase 3 are selected in the two-phase operation, the magnetic flux (hollow arrow in the figure) generated in the iron core 20 by the current flowing through the inner coil 12 (phase 2) is generated in the positive direction (from -X direction to +X direction in the figure) in the inner iron core 22, and in the opposite direction (from +X direction to -X direction in the figure) in the first outer iron core 21 and the second outer iron core 23.

[0076] In contrast, the magnetic flux generated in the core 20 by the current flowing through the second outer coil 13 (phase 3) (the arrow with the shaded line in the figure) is generated in the positive direction (from -X direction to +X direction in the figure) in the second outer core 23, and in the opposite direction (from +X direction to -X direction in the figure) in the inner core 22 and the first outer core 21.

[0077] That is, from the schematic representation of the direction of magnetic flux Figure 4 As indicated by the arrows, when the current flowing through the inner coil 12 (phase 2) and the second outer coil 13 (phase 3) is in the same direction, the direction of the DC magnetic flux generated in the inner core 22 due to the inner coil 12 (phase 2) is opposite to the direction of the DC magnetic flux generated in the inner core 22 due to the second outer coil 13 (phase 3). Furthermore, the direction of the DC magnetic flux generated in the second outer core 23 due to the second outer coil 13 (phase 3) is opposite to the direction of the DC magnetic flux generated in the second outer core 23 due to the inner coil 12 (phase 2).

[0078] In addition, such as Figure 5 As shown, when phase 1 and phase 3 are selected in the two-phase operation, the magnetic flux (hollow arrow in the figure) generated in the iron core 20 by the current flowing through the first outer coil 11 (phase 1) is generated in the positive direction (from -X direction to +X direction in the figure) in the first outer iron core 21, and in the opposite direction (from +X direction to -X direction in the figure) in the inner iron core 22 and the second outer iron core 23.

[0079] In contrast, the magnetic flux generated in the core 20 by the current flowing through the second outer coil 13 (phase 3) (the arrow with the shaded line in the figure) is generated in the positive direction (from -X direction to +X direction in the figure) in the second outer core 23, and in the opposite direction (from +X direction to -X direction in the figure) in the inner core 22 and the first outer core 21.

[0080] That is, from the schematic representation of the direction of magnetic flux Figure 5As indicated by the arrows, when the current flowing through the first outer coil 11 (phase 1) and the second outer coil 13 (phase 3) has the same direction, the direction of the DC magnetic flux generated in the first outer core 21 due to the first outer coil 11 (phase 1) is opposite to the direction of the DC magnetic flux generated in the first outer core 21 due to the second outer coil 13 (phase 3). Furthermore, the direction of the DC magnetic flux generated in the second outer core 23 due to the second outer coil 13 (phase 3) is opposite to the direction of the DC magnetic flux generated in the second outer core 23 due to the first outer coil 11 (phase 1). Although detailed explanation is omitted, this applies to both two-phase operation (where phase 1 and phase 2 are selected) and three-phase operation.

[0081] In this DC-DC converter 10 configuration, by increasing the number of voltage conversion sections 14, 15, and 16 to be driven, the output current ripple can be reduced. Furthermore, as the number of voltage conversion sections 14, 15, and 16 to be driven increases, switching losses increase, while conduction losses decrease. The control device CTR uses a graph or similar representation of the energy efficiency of the DC-DC converter 10 to select the number of voltage conversion sections 14, 15, and 16 to be driven, taking into account the losses of each number of voltage conversion sections 14, 15, and 16 to be driven. Additionally, the control device CTR selects the phase to be driven in single-phase and two-phase operation. As described later, in single-phase operation, the control device CTR selects voltage conversion section 15 (phase 2), i.e., the inner coil 12. Furthermore, when operating in two-phase mode, the control device CTR can select voltage conversion unit 15 (phase 2) and third voltage conversion unit 16 (phase 3) as described above, or it can select first voltage conversion unit 14 (phase 1) and third voltage conversion unit 16 (phase 3), or it can select first voltage conversion unit 14 (phase 1) and voltage conversion unit 15 (phase 2). However, in the case of three-phase operation, all phases from first voltage conversion unit 14 (phase 1) to third voltage conversion unit 16 (phase 3) are operated, so there is no choice of phase.

[0082] Next, the gaps 26 to 28 provided in the core 20 will be explained, and the reason for selecting the voltage conversion unit 15 (phase 2), i.e., the inner coil 12, during single-phase operation will be explained. Here, the gaps 26 to 28 are designed to be optimal for three-phase operation.

[0083] Figure 6 This is a diagram used to illustrate gaps 26 to 28.

[0084] (Three-phase movement)

[0085] The parameters of each part of the core 20 are defined as follows.

[0086] Magnetic path length from the outer core sections 21 and 23 through the inner core section 22: l i

[0087] Magnetic path length from the outer core sections 21 and 23 through the outer core sections 21 and 23: l o

[0088] Magnetic reluctance from the outer core sections 21 and 23 through the inner core section 22: R mi

[0089] The magnetic reluctance through the outer core sections 21 and 23 is: R mo

[0090] The length of the gap 27 in the inner core section 22: t i

[0091] The lengths of the gaps 26 and 28 between the outer core sections 21 and 23: t o

[0092] Vacuum permeability: μ0

[0093] Absolute permeability of core 20: μ

[0094] Relative permeability of core 20: μ r =μ0 / μ

[0095] Cross-sectional area of ​​core 20: A

[0096] Number of turns in coils 11 to 13: N

[0097] Current flowing through coils 11 to 13: I

[0098] magnetoresistive R mi and magnetic reluctance R mo They are represented by the following equation (1).

[0099]

Number 1

[0100]

[0101] When observed from the outer iron core sections 21 and 23, the magnetic flux is directed towards l. i magnetic circuit and l o The magnetic circuit is shunted, therefore the magnetic flux Φ generated from this phase... o It is represented by the following equation (2).

[0102]

Number 2

[0103]

[0104] When viewed from the inner core section 22, the magnetic flux is directed towards l. i The two magnetic circuits are shunt, therefore the magnetic flux Φ generated from this phasei It is represented by the following equation (3).

[0105]

Number 3

[0106]

[0107] The magnetic flux Φ flowing from one side of the outer core 21, 23 to the other side of the outer core 21, 23 o2o It is represented by the following equation (4).

[0108]

Number 4

[0109]

[0110] The magnetic flux Φ flowing from the inner core 22 to one of the outer cores 21, 23 i2o It is represented by the following equation (5).

[0111]

Number 5

[0112]

[0113] Therefore, as a result of the cancellation by the outer core portions 21 and 23, the remaining magnetic flux Φ o It is represented by the following equation (6).

[0114]

Number 6

[0115]

[0116] Similarly, as a result of being canceled out by the inner core portion 22, the remaining magnetic flux Φ i It is represented by the following equation (7).

[0117]

Number 7

[0118]

[0119] The effect of magnetic coupling is greatest when the remaining magnetic flux is 0 as a result of the cancellation by the outer iron cores 21 and 23 and the inner iron core 22, so the following equation (8) holds.

[0120]

Number 8

[0121]

[0122] At this point, when the magnetic reluctance is expressed by the size parameter, it becomes the following equation (9).

[0123]

Number 9

[0124]

[0125] Alternatively, when expressed by relative permeability, it becomes the following equation (10).

[0126]

Number 10

[0127]

[0128] Thus, the length t of the outer gaps 26 and 28 and the inner gap 27, which have the greatest magnetic coupling effect, is... o t i In other words, the lengths t of the outer clearances 26 and 28 and the inner clearance 27 for optimal efficiency during three-phase operation. o t i Each core 20 can utilize its own magnetic circuit length l o l i The difference and relative permeability are expressed relatively. Furthermore, the length t of the inner gap 27... i It must be longer than the outer gap of 26 and 28 by t. o big.

[0129] Next, the lengths t of the outer gaps 26 and 28 and the inner gap 27 are measured. o t i This section explains how to set the optimal value. Figure 7 This is a diagram used to illustrate the leakage flux of core 20. Figure 8 This is a graph showing the relationship between magnetic flux density B, magnetic field strength H, and permeability μ. Figure 9 This indicates the length t of the gap, which is 26 to 28. o t i A graph showing the relationship between inductance and inductance.

[0130] The parameters of each part of the first outer core 21 are defined as follows.

[0131] Magnetic reluctance of the leakage flux magnetic circuit: R moLeak

[0132] Magnetic resistance of the air section: R moAir

[0133] The magnetic reluctance within the outer core portion 21 of the coil 11 is: R moCore

[0134] Magnetic resistance of outer gap 26: R moGap

[0135] The length of the iron core in the portion containing coil 11: l coil

[0136] At this time, R moLeak =R moAir +R moCore +R moGapFurthermore, the leakage flux of the first outer core portion 21 is represented by the following equation (11).

[0137]

Number 11

[0138]

[0139] In addition, the inductance caused by leakage flux is represented by the following equation (12).

[0140]

Number 12

[0141]

[0142] At this point, the parameters that vary depending on the design of the outer gap 26 are the relative permeability μ and the length t of the outer gap 26. o Additionally, such as Figure 8 As shown, the relative permeability μ follows the BH curve, therefore it is related to the length t of the outer gap 26. o Related. The length t of the outer gap 26. o The relationship between inductance and the outer gap length t is plotted on this curve, where the inductance is at its maximum. o Regardless of whether it is greater than or less than the length t o Inductance will decrease (refer to) Figure 9 ).

[0143] The same applies to the outer gap 28 and inner gap 27 on the other side, but if the length t of the outer gaps 26 and 28 is maintained in order to counteract the DC magnetic flux in the core 20... o The length t of the inner gap 27 i The relative relationship (refer to equation (10)) means that the gap length t between the two sides cannot be expressed as... o t i It is also set to maximize the inductance. Therefore, as Figure 9 As shown, the preferred method is to use the gap length t between the two sides. o t i The design is forced to deviate from the point of maximum inductance, and is carried out at the optimal point where the inductance is balanced between phases.

[0144] Figure 10 This is a graph showing the current correlation of ripple during three-phase operation. Figure 11 This is a diagram showing the relationship between the current and inductance of coils 11 to 13.

[0145] In the above explanation, it is assumed that the permeability μ of the core 20 is constant regardless of its location. However, when considering leakage flux, if the magnetic flux in the core 20 is designed to be balanced at a certain current value, the change in permeability μ from the balance point is different at other current values. Therefore, the DC magnetic flux is unbalanced between phases, and the inductance of each phase is different. For example, when the inductance is balanced at a certain current value I0, the following equations (13) and (14) hold according to the condition for eliminating the magnetic flux in the core.

[0146]

Number 13

[0147]

[0148]

Number 14

[0149]

[0150] In the core 20, the inner gap 27 is longer than the outer gaps 26 and 28. Therefore, for the magnetic permeability μ of the core 20 that can eliminate the magnetic flux within the magnetic circuit, the inner core portion 22 is larger than the outer core portions 21 and 23. That is, the inner core portion 22 is used in the low magnetic flux region, and the outer core portions 21 and 23 are used in the high magnetic flux region. Figure 10 As shown, during three-phase operation, regarding the characteristics of the BH curve, as the system moves from the equilibrium point to the low current side, the change in permeability μ of the outer core sections 21 and 23 used in high flux increases. Consequently, in the outer core sections 21 and 23 (outer coils 11 and 13), compared to the inner core section 22 (inner coil 12), the inductance is more current-dependent, and the inductance value increases at low current values, thus resulting in relatively smaller ripple.

[0151] (Single-phase action)

[0152] On the other hand, in single-phase operation, when the inner coil 12 is selected, due to the length t of the gap 26 to 28... o t i Unlike other methods, DC magnetic flux is restricted and difficult to saturate, therefore the inductance increases even with a larger current. That is, when designing based on the constraints of three-phase operation, under the low current conditions of single-phase operation, such as... Figure 11 As shown, the inductance of the inner coil 12 is greater than that of the outer coils 11 and 13. Therefore, in order to reduce the ripple during single-phase operation, it is preferable to select the inner coil 12 and operate it.

[0153] Various embodiments have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that those skilled in the art will conceive of various modifications or alterations within the scope of the technical solutions described, and these modifications or alterations naturally fall within the technical scope of the present invention. Furthermore, the constituent elements of the above embodiments can be combined arbitrarily without departing from the spirit of the invention.

[0154] In addition, at least the following matters are described in this specification. Furthermore, although corresponding components and the like are shown in parentheses in the above embodiments, the present invention is not limited thereto.

[0155] (1) A control device (control device CTR) for a power conversion device (DC-DC converter 10), the power conversion device using a three-phase magnetically coupled reactor (three-phase magnetically coupled reactor 1), wherein,

[0156] The three-phase magnetically coupled reactor includes:

[0157] First outer coil (first outer coil 11);

[0158] Second outer coil (second outer coil 13);

[0159] The inner coil (inner coil 12) is disposed between the first outer coil and the second outer coil; and

[0160] The core (core 20) includes a first outer core portion (first outer core portion 21) wound around the first outer coil, a second outer core portion (second outer core portion 23) wound around the second outer coil, and an inner core portion (inner core portion 22) wound around the inner coil.

[0161] The first outer core portion, the second outer core portion, and the inner core portion extend in a first direction (X-axis direction) and are arranged in a second direction (Y-axis direction) orthogonal to the first direction.

[0162] The first outer core portion, the second outer core portion, and the inner core portion are connected at one end in the first direction by a first connecting portion (first connecting portion 24) extending in the second direction.

[0163] The first outer core portion, the second outer core portion, and the inner core portion are connected at their other ends in the first direction by a second connecting portion (second connecting portion 25) extending in the second direction.

[0164] The magnetic flux of the first outer core, the second outer core, and the inner core is configured such that the direction of the DC magnetic flux generated in the core due to other coils wound in other cores is opposite to the direction of the DC magnetic flux generated in the core due to the coils wound in any core.

[0165] The first outer core portion and the second outer core portion each have an outer gap (outer gap 26, 28) at the center in the first direction.

[0166] The inner core portion has an inner gap (inner gap 27) at its center in the first direction, which is longer than the outer gap in the first direction.

[0167] The control device can switch between single-phase operation, two-phase operation, and three-phase operation.

[0168] The single-phase operation is achieved by allowing current to flow through any one of the first outer coil, the second outer coil, and the inner coil.

[0169] The two-phase operation is achieved by allowing current to flow through any two of the following coils: the first outer coil, the second outer coil, and the inner coil.

[0170] The three-phase operation is achieved by allowing current to flow through all the coils of the first outer coil, the second outer coil, and the inner coil.

[0171] In the single-phase operation, the inner coil is selected.

[0172] According to (1), the first outer core portion and the second outer core portion each have an outer gap at the center in the first direction, and the inner core portion has an inner gap at the center in the first direction with a length greater than the outer gap. Therefore, the three-phase inductance can be balanced to reduce the ripple current during three-phase operation. In addition, the inner coil has a larger inductance than the outer coil due to the different gap lengths. Therefore, by selecting the inner coil during single-phase operation, the ripple current and losses during single-phase operation can be reduced.

[0173] (2) The control device for the power conversion device according to (1), wherein,

[0174] The control device selects the first outer coil and the second outer coil during the two-phase operation.

[0175] According to (2), the first outer coil and the second outer coil are selected in two-phase operation, and the inner coil is selected in single-phase operation. Therefore, the difference in operating frequency can be suppressed and the load of each coil can be equalized.

Claims

1. A control device for a power conversion device, wherein the power conversion device uses a three-phase magnetically coupled reactor, wherein, The three-phase magnetically coupled reactor includes: First outer coil; Second outer coil; The inner coil is disposed between the first outer coil and the second outer coil; and The iron core includes a first outer iron core portion wound around the first outer coil, a second outer iron core portion wound around the second outer coil, and an inner iron core portion wound around the inner coil. The first outer core portion, the second outer core portion, and the inner core portion extend in a first direction and are arranged in a second direction orthogonal to the first direction. The first outer core portion, the second outer core portion, and the inner core portion are connected at one end in the first direction by a first connecting portion extending in the second direction. The first outer core portion, the second outer core portion, and the inner core portion are connected at their other ends in the first direction by a second connecting portion extending in the second direction. The magnetic flux of the first outer core, the second outer core, and the inner core is configured such that the direction of the DC magnetic flux generated in the core due to other coils wound in other cores is opposite to the direction of the DC magnetic flux generated in the core due to the coils wound in any core. The first outer core portion and the second outer core portion each have an outer gap at the center in the first direction. The inner core portion has an inner gap at its center in the first direction, the length of which is greater than that of the outer gap in the first direction. The control device can switch between single-phase operation, two-phase operation, and three-phase operation. The single-phase operation is achieved by allowing current to flow through any one of the first outer coil, the second outer coil, and the inner coil. The two-phase operation is achieved by allowing current to flow through any two of the following coils: the first outer coil, the second outer coil, and the inner coil. The three-phase operation is achieved by allowing current to flow through all the coils of the first outer coil, the second outer coil, and the inner coil. In the single-phase operation, the inner coil is selected.

2. The control device for the power conversion device according to claim 1, wherein, The control device selects the first outer coil and the second outer coil during the two-phase operation.

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