Control device for a power conversion device

Abstract

A control device of a power conversion device capable of suppressing variation of current at the time of switching from single-phase operation to two-phase operation and at the time of switching from two-phase operation to single-phase operation is provided. A DC-DC converter (10) is provided with a three-phase magnetic coupling reactor (1) provided with a first outer coil (11), a second outer coil (13), an inner coil (12), and a core (20), and the directions of magnetic fluxes generated in the first outer coil (11), the second outer coil (13), and the inner coil (12) are opposite to each other regardless of any combination. A control device (CTR) of the DC-DC converter (10) is capable of switching single-phase operation, two-phase operation, and three-phase operation, in the two-phase operation, two phases of the first outer coil (11) and the second outer coil (13) are selected, and in single-phase operation before the two-phase operation or single-phase operation after the two-phase operation, either one of the first outer coil (11) and the second outer coil (13) is selected.

Description

Technical Field

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

[0002] In DC-DC converters of electric motor vehicles and HEVs (Hybrid Electric Vehicles), reactors constructed by mounting coils around an iron core are used. In recent years, to adjust the output current ripple of DC-DC converters, the use of multiphase magnetically coupled reactors has been proposed. In such multiphase converters, the losses are known to vary depending on the number of operating phases.

[0003] For example, in Patent Document 1, a loss map centered on current is proposed, and the operation is performed with the most efficient number of phases.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-153240 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] Patent Document 1 describes a DC-DC converter that utilizes a four-phase reactor with two integrated two-phase core magnetically coupled reactors, instead of a three-phase or higher integrated core magnetically coupled reactor. In a two-phase integrated core magnetically coupled reactor, the phase operating on a core-by-core basis is uniquely determined when the number of operating phases is reduced or increased. In contrast, in a DC-DC converter using a three-phase or higher integrated core magnetically coupled reactor, the operating phase is not uniquely determined when the number of operating phases is reduced or increased.

[0009] In DC-DC converters that use three or more phase cores integrated with magnetically coupled reactors, current fluctuations may occur when switching from single-phase operation to two-phase operation, or from two-phase operation to single-phase operation, if the phase to be operated is not properly selected.

[0010] The present invention provides a control device for a power conversion device that can suppress current fluctuations when switching from single-phase operation to two-phase operation and when switching from two-phase operation to single-phase operation.

[0011] Methods for solving problems

[0012] This invention provides a control device for a power conversion device, which uses a multiphase magnetically coupled reactor, wherein...

[0013] The multiphase magnetically coupled reactor includes:

[0014] First outer coil;

[0015] Second outer coil;

[0016] The inner coil is disposed between the first outer coil and the second outer coil; and

[0017] The core comprises: a first outer core portion on which the first outer coil is wound; a second outer core portion on which the second outer coil is wound; and an inner core portion on which the inner coil is wound.

[0018] The first outer core portion, the second outer core portion, and the inner core portion extend along a first direction and are arranged along a second direction orthogonal to the first direction.

[0019] 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 along the second direction.

[0020] 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 along the second direction.

[0021] The directions of the magnetic flux generated in the first outer coil, the second outer coil, and the inner coil are configured to be opposite to each other regardless of the combination used.

[0022] The control device can switch between single-phase operation, two-phase operation, and three-phase operation.

[0023] The single-phase operation is performed by allowing current to flow through any one of the first outer coil, the second outer coil, and the inner coil.

[0024] The two-phase operation is performed by allowing current to flow through any two of the first outer coil, the second outer coil, and the inner coil.

[0025] The three-phase operation is performed by allowing current to flow through all coils of the first outer coil, the second outer coil, and the inner coil.

[0026] In the two-phase operation, the first outer coil and the second outer coil are selected as the two phases.

[0027] In the single-phase operation before the two-phase operation or the single-phase operation after the two-phase operation, either the first outer coil or the second outer coil is selected.

[0028] Invention Effects

[0029] According to the present invention, when switching from single-phase operation to two-phase operation and when switching from two-phase operation to single-phase operation, the already operated phases continue to operate as before, minimizing the number of phases whose operating states change, thereby suppressing current fluctuations. Attached Figure Description

[0030] Figure 1 This is the circuit diagram of a three-phase interleaved DC-DC converter 10.

[0031] Figure 2 This is a perspective view of the three-phase magnetically coupled reactor 1 used in the DC-DC converter 10.

[0032] Figure 3 This is a plan view of the three-phase magnetically coupled reactor 1 and a diagram showing the driving modes of the three-phase magnetically coupled reactor 1.

[0033] Figure 4 This is a diagram showing the magnetic flux of each core section during the two-phase operation of phases 2 and 3.

[0034] Figure 5 This is a diagram showing the magnetic flux of each core section during the two-phase operation of phases 1 and 3.

[0035] Figure 6 yes Figure 3 The timing diagram for mode 1.

[0036] Figure 7 yes Figure 3 The timing diagram for mode 2.

[0037] Explanation of reference numerals in the attached figures

[0038] 1. Three-phase magnetically coupled reactor (multi-phase magnetically coupled reactor)

[0039] 10 DC-DC converters

[0040] 11 First outer coil

[0041] 12 Inner Coils

[0042] 13 Second outer coil

[0043] 20 Iron Heart

[0044] 21 First outer core section

[0045] 22 Inner core section

[0046] 23 Second outer core section

[0047] 24 First connecting section

[0048] 25 Second connecting section

[0049] CTR control device Detailed Implementation

[0050] Hereinafter, the control device of a power conversion device according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0051] First, a three-phase interleaved DC-DC converter, which is an example of a power conversion device and is the controlled object of the control device of the present invention, will be described. Figure 1 This is a circuit diagram showing a three-phase interleaved DC-DC converter.

[0052] 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 a three-phase reactor) having three coils 11 to 13, switching units SW1, SW2, SW3, diodes D1, D2, D3, a smoothing capacitor C2, and a control device CTR.

[0053] 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.

[0054] In the three-phase reactor 1, the input terminals of coils 11-13 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, and coil 11 constitutes 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, and coil 12 constitutes 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, and coil 13 constitutes 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 freewheeling diode connected in parallel with the switching element.

[0055] It should be noted that "three-phase" in three-phase reactor 1 refers to the number of switching units being three. The following description of single-phase operation refers to one switching unit operating in the first voltage switching unit 14 to the third voltage switching unit 16; two-phase operation refers to two switching units operating in the first voltage switching unit 14 to the third voltage switching unit 16; and three-phase operation refers to three switching units operating in the first voltage switching unit 14 to the third voltage switching unit 16. In the following description, the first voltage switching unit 14 can be referred to as "phase 1," the second voltage switching unit 15 as "phase 2," and the third voltage switching unit 16 as "phase 3."

[0056] Each switching element of the switching section SW1 to SW3 is controlled to turn on and off according to the signal from the control device CTR (see reference). Figure 6 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 time, the voltage V1 is boosted in DC mode and a voltage V2 is output. The switching operation of the switching sections SW1, SW2, and SW3 of the voltage conversion sections 14, 15, and 16 is controlled by a pulsed switching signal with a predetermined duty cycle sent from the switching control unit to the DC-DC converter 10.

[0057] When the switching elements of voltage conversion sections 14, 15, and 16 are switched on and off, during the on-off 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-off 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 current flowing through one voltage conversion section of the DC-DC converter 10 is output during the off-off 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, interleaved control is performed, staggering the on-off switching phases of the driven voltage conversion sections 14, 15, and 16 by 180 degrees. In the case of three-phase operation where all voltage conversion sections 14, 15, and 16 of the DC-DC converter 10 are driven, interleaved control is performed to stagger the switching phases of each voltage conversion section 14, 15, and 16 by 120 degrees.

[0058] 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.

[0059] 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 that houses them.

[0060] For example, the iron core 20 is constructed by stacking thin sheet-like electromagnetic steel plates. 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 along the X-axis and are arranged parallel to each other along the Y-axis; a first connecting portion 24, which extends along the Y-axis at one end in the X-axis direction and connects the first outer core portions 21, the inner core portions 22, and the second outer core portions 23; and a second connecting portion 25, which extends along the Y-axis at the other end in the X-axis direction and connects the first outer core portions 21, the inner core portions 22, and the second outer core portions 23. In other words, the core 20 is a planar core structure 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.

[0061] 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 coil 12, and the second outer coil 13 extend along the X-axis and are arranged along the Y-axis. The number of turns and the winding direction of each coil 11 to 13 are identical.

[0062] In this three-phase reactor 1, when current flows through any two or more of the coils 11, 12, and 13, the directions of the magnetic flux generated in each coil (hereinafter referred to as the magnetic flux direction) are opposite to each other in any combination, thus reducing the magnetic flux generated in the core. As a result, magnetic saturation of the core 20 can be suppressed.

[0063] In the DC-DC converter 10 configured in this way, the output current ripple can be reduced by increasing the number of driven voltage conversion sections 14, 15, and 16. Furthermore, as the number of driven voltage conversion sections 14, 15, and 16 increases, switching losses increase, but conduction losses decrease. The control device CTR selects the number of driven voltage conversion sections 14, 15, and 16 using a mapping representing the energy efficiency of the DC-DC converter 10, taking into account the losses of each of the driven voltage conversion sections 14, 15, and 16. Additionally, the control device CTR selects the phase to be driven in two-phase operation and three-phase operation. The control device CTR of the present invention... Figure 3 The DC-DC converter 10 is driven in either Mode 1 or Mode 3, as shown below, and will be described in detail later.

[0064] (Three-phase movement)

[0065] In the case of three-phase operation, where all phases 1 to 3 operate, all voltage conversion units 14, 15, and 16 (phases 1 to 3) operate, thus there is no choice in which phases are selected. On the other hand, in the case of two-phase operation, any two phases of voltage conversion units 14, 15, and 16 (phases 1 to 3) operate, and in the case of single-phase operation, only one phase of voltage conversion units 14, 15, and 16 (phases 1 to 3) operates. Therefore, there is a choice in which phases operate in both two-phase and single-phase operation.

[0066] (Two-phase action)

[0067] Therefore, the two-phase action will be explained first.

[0068] Figure 4 This is a diagram showing the magnetic flux of each core section during the two-phase operation of phases 2 and 3. Figure 5 This is a diagram showing the magnetic flux of each core section during the two-phase operation of phases 1 and 3.

[0069] like Figure 4 As shown, when phases 2 and 3 are selected in the two-phase operation, the magnetic flux generated in the core 20 by the current flowing through the inner coil 12 (phase 2) is generated in the inner core 22 in the positive direction (upward in the figure), and in the first outer core 21 and the second outer core 23 in the opposite direction (downward in the figure). The magnetic flux is greatest in the inner core 22, and is less than but approximately equal to that in the first outer core 21 and the second outer core 23, which are located at equal distances from the inner core 22.

[0070] In response, the magnetic flux generated in the core 20 by the current flowing through the second outer coil 13 (phase 3) is generated in the positive direction (upward in the figure) in the second outer core 23, and in the opposite direction (downward in the figure) in the inner core 22 and the first outer core 21. The magnetic flux is greatest in the second outer core 23, less in the inner core 22 which is closer to the second outer core 23, and least in the first outer core 21 which is farther from the second outer core 23.

[0071] Based on the schematic representation of the direction and quantity 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 the same, the magnetic flux through the inner core 22 (phase 2) and the second outer core 23 (phase 3) is not uniform. This also applies when phase 1 and phase 2 are selected in a two-phase operation.

[0072] On the other hand, such as Figure 5 As shown, when phase 1 and phase 3 are selected in the two-phase operation, the magnetic flux generated in the core 20 by the current flowing through the first outer core 21 (phase 1) is generated in the positive direction (upward in the figure) in the first outer core 21, and in the opposite direction (downward in the figure) in the inner core 22 and the second outer core 23. The magnetic flux is the largest in the first outer core 21, less in the inner core 22 which is closer to the first outer core 21, and the least in the second outer core 23 which is farther from the first outer core 21.

[0073] In response, the magnetic flux generated in the core 20 by the current flowing through the second outer coil 13 (phase 3) is generated in the positive direction (upward in the figure) in the second outer core 23, and in the opposite direction (downward in the figure) in the inner core 22 and the first outer core 21. The magnetic flux is greatest in the second outer core 23, less in the inner core 22 which is closer to the second outer core 23, and least in the first outer core 21 which is farther from the second outer core 23.

[0074] Based on the schematic representation of the direction and quantity of magnetic flux Figure 5 As can be seen from the arrow, when the current flowing through the first outer core 21 (phase 1) and the second outer coil 13 (phase 3) is the same, the magnetic flux through the first outer core 21 (phase 1) and the second outer core 23 (phase 3) becomes uniform.

[0075] Thus, by selecting phase 1 and phase 3 in the two-phase operation, the magnetic flux through the first outer core 21 (phase 1) and the second outer coil 13 (phase 3) becomes uniform, resulting in approximately equal magnetic characteristics in both phases and good control stability. Therefore, phase 1 and phase 3 are selected in the two-phase operation. Therefore, as... Figure 3 As shown in modes 1 to 3, the control device CTR selects phase 1 and phase 3 as the phases that operate in the two-phase operation.

[0076] (Single-phase action)

[0077] Next, also refer to Figure 6 and Figure 7 Explain the single-phase operation. Figure 6 yes Figure 3 The timing diagram for mode 1. Figure 7 yes Figure 3 The timing diagram for Mode 2. Figure 6 and Figure 7 In the diagram, IL1 is the current flowing through the first outer coil 11, IL2 is the current flowing through the inner coil 12, IL3 is the current flowing through the second outer coil 13, and I1 is the input current of the three-phase reactor 1 (refer to...). Figure 1 ).

[0078] In single-phase operation, phase 2 is typically selected. Since phases 1 and 3 are selected in two-phase operation as described above, to balance the operating frequency and equalize the load on each coil, it is considered to use phase 2 in single-phase operation. Figure 3 Pattern 2). In this case, such as Figure 7 As shown, when switching from single-phase operation to two-phase operation, the control device CTR stops the on / off control of switch SW2 and starts the on / off control of switch SW1 and switch SW3. That is, the control device CTR completely stops switch SW2, which has already been performing on / off switching operations, and begins to control the on / off operation of switch SW1 and switch SW3, which have been stopped up to this point. At this time, the fluctuation of the input current I1 increases.

[0079] The same applies to the switching from two-phase operation to single-phase operation. That is, when switching from two-phase operation to single-phase operation, the control device CTR completely stops the switching sections SW1 and SW3, which have been controlled for on / off, and starts controlling the switching section SW2, which has been stopped so far. However, in this case, the fluctuation of the input current I1 also increases.

[0080] In this invention, phase 1 or phase 3 is selected during single-phase operation. This is relevant for selecting phase 1 during single-phase operation. Figure 3 Mode 1 and selecting phase 3 in single-phase action Figure 3The same applies to Mode 3, so only the case of Mode 1 (selecting phase 1) will be explained here, and the case of Mode 3 (selecting phase 3) will be omitted.

[0081] In passing Figure 3 In the case of selecting phase 1 in the single-phase operation shown in Mode 1, such as Figure 6 As shown, when switching from single-phase operation to two-phase operation, the control device CTR only needs to activate switch SW3. That is, while maintaining the on / off control of switch SW1, which is already under on / off control, the control device CTR begins to activate / off control of switch SW3, which has been stopped so far. Furthermore, the control device CTR maintains the stopped state of switch SW2 as before.

[0082] Compare Figure 6 and Figure 7 It can be seen that when choosing Figure 3 When selecting Mode 1 (or Mode 3), compared to selecting... Figure 3 Compared to Mode 2, the variation in input current I1 is smaller. This is because, during the switch from single-phase to two-phase operation, the operating phase continues to operate as before, minimizing the number of phases whose operating state changes. According to Mode 1 (Mode 3), by suppressing the variation in input current I1, controllability is stabilized. Consequently, the region capable of operating with a smaller number of phases increases, thereby improving the efficiency of the DC-DC converter 10.

[0083] The same applies to the switching from two-phase operation to single-phase operation. That is, when switching from two-phase operation to single-phase operation, the control device CTR only needs to completely stop the switch SW3 in the switch section SW1 and switch section SW3 that have been controlled for on / off switching. In this case, the fluctuation of the input current I1 can be reduced.

[0084] In addition, such as Figure 6 As shown, during the switch from single-phase operation to two-phase operation (phase switching period), it is preferable that the control device CTR maintains the duty cycle of the switching section SW1 and gradually increases the duty cycle of the switching section SW3. Specifically, the control device CTR gradually increases the conduction time while maintaining the on-off switching cycle. This further suppresses the current fluctuation during the switch from single-phase operation to two-phase operation, thereby enabling a smooth switching process.

[0085] Conversely, during the switch from two-phase operation to single-phase operation (phase switching period), it is preferable that the control device CTR maintains the duty cycle of the switching section SW1 and gradually reduces the duty cycle of the switching section SW3. Specifically, the control device CTR gradually reduces the conduction time while maintaining the on-off switching cycle. This further suppresses current fluctuations during the switch from two-phase operation to single-phase operation, thereby enabling smooth switching.

[0086] It should be noted that the adjustment of the duty cycle during this switching is the same when switching from two-phase operation to three-phase operation (during phase switching) and when switching from three-phase operation to two-phase operation (during phase switching). It is sufficient to gradually increase the duty cycle of the switch connected to the phase whose operation state changes from stop to drive, and gradually decrease the duty cycle of the switch connected to the phase whose operation state changes from drive to stop.

[0087] Various embodiments have been described above with reference to the accompanying drawings, but the present invention is not limited to these 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 it should be understood that these modifications and alterations also 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.

[0088] At least the following items are described in this specification. It should be noted that although the corresponding components and the like in the above embodiments are shown in parentheses, the present invention is not limited thereto.

[0089] For example, although the DC-DC converter 10 using a three-phase magnetically coupled reactor 1 is shown in the above embodiment, it can also be applied to a DC-DC converter using a multi-phase magnetically coupled reactor with three or more phases, but the core of the multi-phase magnetically coupled reactor needs to be integrated when there are three or more phases.

[0090] Furthermore, in this invention, a planar core structure is shown, in which the first outer core portion 21, the inner core portion 22, and the second outer core portion 23 are on the same plane. However, this invention is not limited to this, and it may also be a three-dimensional core structure in which the first outer core portion 21, the inner core portion 22, and the second outer core portion 23 are arranged at 120° intervals along the circumference.

[0091] At least the following items are described in this specification. It should be noted that although the corresponding components and the like in the above embodiments are shown in parentheses, the present invention is not limited thereto.

[0092] (1) A control device (control device CTR) for a power conversion device (DC-DC converter 10), the power conversion device using a multiphase magnetically coupled reactor (three-phase magnetically coupled reactor 1), wherein,

[0093] The three-phase magnetically coupled reactor includes:

[0094] First outer coil (first outer coil 11);

[0095] Second outer coil (second outer coil 13);

[0096] The inner coil (inner coil 12) is disposed between the first outer coil and the second outer coil; and

[0097] The core (core 20) comprises: a first outer core portion (first outer core portion 21) on which the first outer coil is wound; a second outer core portion (second outer core portion 23) on which the second outer coil is wound; and an inner core portion (inner core portion 22) on which the inner coil is wound.

[0098] The first outer core portion, the second outer core portion, and the inner core portion extend along a first direction (X-axis direction) and are arranged along a second direction (Y-axis direction) orthogonal to the first direction.

[0099] 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 along the second direction.

[0100] 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 along the second direction.

[0101] The directions of the magnetic flux generated in the first outer coil, the second outer coil, and the inner coil are configured to be opposite to each other regardless of the combination used.

[0102] The control device can switch between single-phase operation, two-phase operation, and three-phase operation.

[0103] The single-phase operation is performed by allowing current to flow through any one of the first outer coil, the second outer coil, and the inner coil.

[0104] The two-phase operation is performed by allowing current to flow through any two of the first outer coil, the second outer coil, and the inner coil.

[0105] The three-phase operation is performed by allowing current to flow through all coils of the first outer coil, the second outer coil, and the inner coil.

[0106] In the two-phase operation, the first outer coil and the second outer coil are selected as the two phases.

[0107] In the single-phase operation before the two-phase operation or the single-phase operation after the two-phase operation, either the first outer coil or the second outer coil is selected.

[0108] According to (1), in two-phase operation, the first outer coil and the second outer coil are selected, thus the amount of magnetic flux through the first outer core and the second outer core becomes uniform. Furthermore, when switching from single-phase operation to two-phase operation, and from two-phase operation to single-phase operation, the operating phase operates as before, minimizing the number of phases with changing operating states, thereby suppressing current fluctuations. As a result, controllability is stable, the area where operation can be performed with fewer phases is increased, and the efficiency of the power conversion device is improved.

[0109] (2) The control device for the power conversion device according to (1), wherein,

[0110] The first outer coil, the second outer coil, and the inner coil are respectively connected to the switching section (switching section SW1, SW3, SW2).

[0111] The control device performs PWM control on the switching section.

[0112] When switching from single-phase operation to two-phase operation, the switch connected to one of the first outer coil and the second outer coil maintains the duty cycle.

[0113] When switching from single-phase operation to two-phase operation, the switch connected to the other of the first outer coil and the second outer coil gradually increases the duty cycle.

[0114] According to (2), the current fluctuation during the switching from single-phase operation to two-phase operation is further suppressed, so that the switching can be carried out smoothly.

[0115] (3) A control device for the power conversion device according to (1) or (2), wherein,

[0116] The first outer coil, the second outer coil, and the inner coil are respectively connected to the switching section (switching section SW1, SW3, SW2).

[0117] The control device performs PWM control on the switching section.

[0118] When switching from the two-phase operation to the single-phase operation, the switch connected to one of the first outer coil and the second outer coil maintains the duty cycle.

[0119] When switching from the two-phase operation to the single-phase operation, the switch connected to the other of the first outer coil and the second outer coil gradually reduces the duty cycle.

[0120] According to (3), the current fluctuation during the switching from two-phase operation to single-phase operation is further suppressed, so that the switching can be carried out smoothly.

Claims

1. A control device for a power conversion device, wherein the power conversion device uses a multiphase magnetically coupled reactor, wherein, The multiphase 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 core comprises: a first outer core portion on which the first outer coil is wound; a second outer core portion on which the second outer coil is wound; and an inner core portion on which the inner coil is wound. The first outer core portion, the second outer core portion, and the inner core portion extend along a first direction and are arranged along 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 along 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 along the second direction. The first outer coil, the second outer coil, and the inner coil are configured such that, in a three-phase operation where current flows in the same direction through all the coils of the first outer coil, the second outer coil, and the inner coil, the magnetic flux generated in the first outer core, the second outer core, and the inner core cancels each other out. The control device can switch between single-phase operation, two-phase operation, and three-phase operation. The single-phase operation is performed 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 performed by allowing current to flow through any two of the first outer coil, the second outer coil, and the inner coil. The three-phase operation is performed by allowing current to flow through all coils of the first outer coil, the second outer coil, and the inner coil. In the two-phase operation, the first outer coil and the second outer coil are selected as the two phases. In the single-phase operation before the two-phase operation or the single-phase operation after the two-phase operation, either the first outer coil or the second outer coil is selected.

2. The control device for the power conversion device according to claim 1, wherein, The first outer coil, the second outer coil, and the inner coil are respectively connected to the switching unit. The control device performs PWM control on the switching section. When switching from single-phase operation to two-phase operation, the switch connected to one of the first outer coil and the second outer coil maintains the duty cycle. When switching from single-phase operation to two-phase operation, the switch connected to the other of the first outer coil and the second outer coil gradually increases the duty cycle.

3. The control device for the power conversion device according to claim 1 or 2, wherein, The first outer coil, the second outer coil, and the inner coil are respectively connected to the switching unit. The control device performs PWM control on the switching section. When switching from the two-phase operation to the single-phase operation, the switch connected to one of the first outer coil and the second outer coil maintains the duty cycle. When switching from the two-phase operation to the single-phase operation, the switch connected to the other of the first outer coil and the second outer coil gradually reduces the duty cycle.

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