Power conversion device

Abstract

Provided is a power conversion device that expands the supportable power conversion range on both the charging side and the discharging side. A DC / DC converter (5) is provided with a bidirectional insulated LLC resonant circuit (15). The circuit (15) includes: a primary side circuit (21) including six primary side switching elements (S1 to S6); a secondary side circuit (22) including four secondary side switching elements (S7-S10); and an LLC circuit (23) located between the transformer (20) and the primary side circuit (21), the circuit (15) being configured so as to be able to perform a charging operation and a discharging operation. The controller (17) is configured so as to change the switching operation mode of each of the primary-side switching elements (S1-S6) and the secondary-side switching elements (S7-S10) in the charging operation and the discharging operation on the basis of switching operation control information relating to a phase shift and a duty ratio set in accordance with the magnitude relationship between the input / output DC voltages.

Description

Technical Field

[0001] The technology to be disclosed relates to a power conversion device (DC / DC converter) that inputs a direct current voltage and converts it into a direct current voltage of a different magnitude and then outputs it. Background Art

[0002] In recent years, the electrification of electric vehicles, hybrid vehicles, and other vehicles has become significant. These vehicles that run on electricity are equipped with high-output batteries as their power source. In order to charge the batteries, these vehicles are also equipped with a charging system (On Board Charger: OBC) that converts AC power, which is a commercial power source, into DC power.

[0003] Most OBCs use an AC / DC converter that converts an AC voltage into a DC voltage and a DC / DC converter that converts a DC voltage output from the AC / DC converter into a different voltage. The conversion of the voltage magnitude is mainly performed by the DC / DC converter.

[0004] Among such DC / DC converters, a resonant DC / DC converter is often used from the viewpoint of improving efficiency. However, a resonant DC / DC converter has a disadvantage that the voltage operating range is narrowed due to the limitation of zero voltage switching (ZVS).

[0005] Commercial power supplies generally use an AC voltage of 100 V to 200 V. In contrast, batteries mounted on vehicles use a high DC voltage of, for example, 48 V to over 400 V. Therefore, it is desirable that a DC / DC converter supports conversion of such a wide range of power, and an expansion of the power conversion range that can be supported is required.

[0006] As for the technology to be disclosed, a technology for expanding the power output range in a resonance-type DC / DC converter has been proposed (Patent Document 1).

[0007] This patent document discloses an isolated DC / DC converter having a predetermined LLC resonant converter circuit. The on-off operation of a switching element disposed on the input side of the LLC resonant converter circuit is switched in different modulation methods. In this way, the magnitude of the voltage output to the LLC resonant circuit side is changed.

[0008] Patent Document 1: Japanese Patent Application Publication No. 2021-035328 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] The technology of Patent Document 1 is based on a specific LLC resonant converter circuit and performs control in the same basic operation as the asymmetric half-bridge method. Therefore, only half of the input voltage can be used, and it is not actually suitable for large power.

[0011] Furthermore, since the duty ratio is controlled to be fixed to a predetermined value (25%, 50%, 75%), the control range of the output voltage is actually narrowed. Furthermore, this technology targets charging operations and therefore does not support discharging operations.

[0012] Therefore, this specification discloses a technology that can effectively expand the power conversion range that can be supported on both the charging side and the discharging side in a DC / DC converter.

[0013] Solutions for solving problems

[0014] The technology to be disclosed relates to a power conversion device including a converter mechanism including a bidirectional insulating LLC resonant circuit and a controller for controlling the converter mechanism, and inputs a DC voltage and converts it into a DC voltage of different magnitude and outputs the converted DC voltage.

[0015] The bidirectional insulated LLC resonant circuit comprises: a transformer having a primary side coil and a secondary side coil; a primary side circuit located on the primary side of the transformer, comprising a primary side input-output terminal pair and six primary side switching elements; a secondary side circuit located on the secondary side of the transformer, comprising a secondary side input-output terminal pair and four secondary side switching elements; and an LLC circuit located between the transformer and the primary side circuit.

[0016] Furthermore, the power conversion device is configured to be capable of performing a charging operation in which a DC voltage is input to the primary-side input / output terminal pair and outputted from the secondary-side input / output terminal pair, and a discharging operation in which a DC voltage is input to the secondary-side input / output terminal pair and outputted from the primary-side input / output terminal pair.

[0017] The controller is configured to have switching action control information related to a duty cycle and a phase shift set according to the magnitude relationship between the input and output DC voltages, and to change the respective switching action modes of the primary side switching element and the secondary side switching element in the charging action and the discharging action based on the switching action control information.

[0018] That is, the power conversion device is a so-called DC / DC converter, including a predetermined bidirectional insulated LLC resonant circuit, and is configured to be capable of performing charging and discharging operations. Moreover, its controller has switching operation control information related to a duty ratio and a phase shift set according to the magnitude relationship between the input and output DC voltages, and changes the switching operation modes of the primary side switching element and the secondary side switching element in the charging and discharging operations based on the switching operation control information.

[0019] In this power conversion device, the duty cycle and phase shift are combined to control the charging and discharging actions according to the magnitude relationship between the input and output DC voltages. Therefore, high-efficiency and high-precision control can be achieved by a simple method, and the supported power conversion range can be effectively expanded on both the charging and discharging sides.

[0020] The primary side circuit may further include an intermediate voltage output portion, and the intermediate voltage output portion causes the intermediate voltage of the primary side voltage, that is, the primary side half voltage, which is the DC voltage input to the primary side input / output terminal pair, to act on the LLC circuit. In this way, when the DC voltage output during the charging operation is greater than the primary side half voltage, the controller controls the duty ratio while causing the primary side voltage and the primary side half voltage to act on the LLC circuit in a switching manner.

[0021] By doing so, the positive and negative waveforms of the voltage applied to the primary side of the transformer can be made equal, and the phenomenon of DC bias magnetization can be suppressed during the charging operation.

[0022] For example, the bidirectional insulated LLC resonant circuit may be configured as follows. The primary side circuit includes: a first branch in which two primary side switching elements are arranged in series; a second branch in which two element pairs consisting of two primary side switching elements connected in series are arranged in series; a third branch in which two primary side capacitors are arranged in series; a fourth branch in which an intermediate capacitor is arranged; a fifth branch in which two diodes are arranged in series; a pair of primary side main lines, one end of which is provided with the primary side input / output terminal pair, and the first branch, the second branch, and the third branch are connected in parallel between the pair of primary side main lines; a pair of bypass lines, the pair of bypass lines are connected in parallel to the portions between the primary side switching elements included in the element pairs in the second branch, and the fourth branch and the fifth branch are connected in parallel to the pair of bypass lines; and a connecting line connected to the portion between the two diodes in the fifth branch and the portion between the two primary side capacitors in the third branch.

[0023] The secondary side circuit comprises: a sixth branch and a seventh branch, on each of which two secondary side switching elements are respectively arranged in series; an eighth branch arranged with a secondary side capacitor; and a pair of secondary side main lines, one end of which is provided with the secondary side input-output terminal pair, and the sixth branch, the seventh branch and the eighth branch are connected in parallel between the pair of secondary side main lines.

[0024] In addition, the power conversion device also has: an upper relay wiring on the primary side, connecting the end of the positive pole side of the primary side coil to the position between the two pairs of elements in the second branch; a lower relay wiring on the primary side, connecting the end of the negative pole side of the primary side coil to the position between the two primary side switching elements in the first branch; an upper relay wiring on the secondary side, connecting the end of the positive pole side of the secondary side coil to the position between the two secondary side switching elements in the sixth branch; and a lower relay wiring on the secondary side, connecting the end of the negative pole side of the secondary side coil to the position between the two secondary side switching elements in the seventh branch, and the LLC circuit has a primary side resonant capacitor and a primary side resonant inductor configured in series on the upper relay wiring on the primary side.

[0025] In this way, the supported power conversion range can be effectively expanded on both the charging side and the discharging side with a relatively simple circuit configuration.

[0026] The bidirectional insulated LLC resonant circuit may further include a secondary-side LLC circuit located between the transformer and the secondary-side circuit.

[0027] By doing so, it is possible to more effectively expand the supported power conversion range on both the charging side and the discharging side.

[0028] The bidirectional insulated LLC resonant circuit may be configured as follows. That is, the primary side circuit comprises: a first branch and a second branch, two primary side switch elements are arranged in series on each of the first branch and the second branch; a third branch in which two primary side capacitors are arranged in series; a pair of primary side main lines, one end of which is provided with the pair of primary side input / output terminals, and the first branch, the second branch, and the third branch are connected in parallel between the pair of primary side main lines; and a connecting line, on which the two primary side switch elements are arranged in series so that the energization directions of both sides are opposite, and the connecting line is connected to a portion between the two primary side switch elements in the second branch and a portion between the two primary side capacitors in the third branch.

[0029] The secondary side circuit comprises: a sixth branch and a seventh branch, on each of which two secondary side switching elements are respectively arranged in series; an eighth branch arranged with a secondary side capacitor; and a pair of secondary side main lines, one end of which is provided with the secondary side input-output terminal pair, and the sixth branch, the seventh branch and the eighth branch are connected in parallel between the pair of secondary side main lines.

[0030] In addition, the power conversion device also has: a primary-side upper relay wiring, which connects the end of the positive pole side of the primary side coil to the position between the two primary-side switching elements in the second branch; a primary-side lower relay wiring, which connects the end of the negative pole side of the primary side coil to the position between the two primary-side switching elements in the first branch; a secondary-side upper relay wiring, which connects the end of the positive pole side of the secondary side coil to the position between the two secondary-side switching elements in the sixth branch; and a secondary-side lower relay wiring, which connects the end of the negative pole side of the secondary side coil to the position between the two secondary-side switching elements in the seventh branch, and the LLC circuit has a primary-side resonant capacitor and a primary-side resonant inductor configured in series on the primary-side upper relay wiring.

[0031] With this circuit configuration, similarly to the above-described bidirectional insulated LLC resonant circuit, it is possible to effectively expand the supported power conversion range on both the charging side and the discharging side with a relatively simple circuit configuration.

[0032] In the case of the bidirectional insulating type LLC resonant circuit, the bidirectional insulating type LLC resonant circuit may further include a secondary-side LLC circuit located between the transformer and the secondary-side circuit.

[0033] By doing so, similarly to the above-mentioned bidirectional insulated LLC resonant circuit, it is possible to more effectively expand the supported power conversion range on both the charging side and the discharging side.

[0034] Effects of the Invention

[0035] According to the disclosed technology, in a DC / DC converter, the power conversion range that can be supported can be effectively expanded on both the charging side and the discharging side. Therefore, a DC / DC converter suitable for OBC and the like can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram showing an application example of the technology to be disclosed.

[0037] Figure 2 It is a diagram showing a bidirectional insulating LLC resonant circuit.

[0038] Figure 3 This is a control block diagram of the controller during charging operation.

[0039] Figure 4 This is a table that summarizes switch action control information.

[0040] Figure 5 is the resonance curve of the LLC circuit.

[0041] Figure 6 This is an example of various waveforms and switching operation patterns during charging operation.

[0042] Figure 7 This is an example of a switching operation mode within the first charging voltage range.

[0043] Fig. 8A is with Figure 7 Schematic diagram of the current path of the corresponding bidirectional isolated LLC resonant circuit.

[0044] Figure 8B is with Figure 7 Schematic diagram of the current path of the corresponding bidirectional isolated LLC resonant circuit.

[0045] Fig. 9 This is an example of an equivalent circuit and a switching operation mode of a bidirectional isolated LLC resonant circuit in the third charging voltage range.

[0046] Fig.10 This is an example of a schematic diagram of an equivalent circuit of a bidirectional isolated LLC resonant circuit and its current path in the fourth charging voltage range.

[0047] Fig.11 This is an example of a switching operation mode within the second discharge voltage range.

[0048] Fig. 12A is with Fig.11 Schematic diagram of the current path of the corresponding bidirectional isolated LLC resonant circuit.

[0049] Fig. 12B is with Fig.11 Schematic diagram of the current path of the corresponding bidirectional isolated LLC resonant circuit.

[0050] Fig.13 This is an example of the effect verification result based on simulation.

[0051] Fig.14 This is an example of the effect verification result based on simulation.

[0052] Fig.15 This is a modified example of a bidirectional insulating LLC resonant circuit.

[0053] Fig.16 This is another method of a bidirectional isolated LLC resonant circuit.

[0054] Description of Reference Numerals

[0055] 1: vehicle; 2: commercial power supply; 3: charging system; 4: battery; 5: DC / DC converter; 6: AC / DC converter; 15: bidirectional insulated LLC resonant circuit; 16: converter mechanism; 17: controller; 17a: voltage balance regulator; 17b: current regulator; 17c: control unit; 17d: drive circuit; 20: transformer; 21: primary side circuit; 22: secondary side circuit; 23: LLC circuit 25: element pair; 30: primary side input / output terminal; 31: first branch; 32: second branch; 33: third branch; 34: fourth branch; 35: fifth branch; 36: primary side main line; 37: bypass line; 38: connection line; 43 : Intermediate voltage output part; 45: Primary side upper relay wiring; 46: Primary side lower relay wiring; 50: Secondary side input and output terminal; 51: Sixth branch; 52: Seventh branch; 53: Eighth branch; 54: Secondary side main line; 55: Secondary side capacitor; 57: Secondary side upper relay wiring; 58: Secondary side lower relay wiring; 60: Secondary side LLC circuit; 61: Secondary side resonant capacitor; 62: Secondary side resonant inductor; S1~S10: Switching element; D1, D2: Diode; C1, C2: Primary side capacitor; C3: Intermediate capacitor; C4: Secondary side capacitor; Cr: Primary side resonant capacitor; Lr: Primary side resonant inductor; Lm: Excitation inductor DETAILED DESCRIPTION

[0056] The following describes the technology to be disclosed. However, the following description is essentially just an example. For the structural elements of the circuit, a prescribed symbol is attached together with the alphanumeric symbol. For convenience, this symbol is sometimes used for explanation or illustration.

[0057] <Overview of Power Conversion Device>

[0058] Figure 1 The example of applying the power conversion device of the disclosed technology to an onboard charging system 3 (OBC) is shown in the figure. The charging system 3 is mounted on a vehicle 1 running on electricity, such as an electric car or a hybrid car, together with a high-power battery 4 for driving and a low-power lead-acid battery 4a for electrical components.

[0059] exist Figure 1The figure above shows the vehicle 1 and the commercial power supply 2 being charged. The commercial power supply 2 outputs a high voltage AC voltage such as 100 V and 200 V. The commercial power supply 2 and the vehicle 1 are connected by a cable to charge the battery 4. At this time, the charging system 3 is interposed between the battery 4 and the commercial power supply 2, and converts the AC voltage into a DC voltage corresponding to the battery 4.

[0060] like Figure 1 As shown in the middle figure, the charging system 3 includes a DC / DC converter 5, an AC / DC converter 6, etc. The AC / DC converter 6 is a device that converts an AC input voltage E1 into a DC output voltage V1, or converts a DC input voltage V4 into an AC output voltage E2.

[0061] The DC / DC converter 5 is a device that inputs a DC voltage and converts it into a DC voltage of different magnitude and then outputs it. That is, it is equivalent to a "power conversion device", and the technology to be disclosed is applied to this DC / DC converter 5.

[0062] The DC / DC converter 5 converts the DC voltage V1 converted by the AC / DC converter 6 into a predetermined DC voltage V2 and outputs it to the battery 4 or the lead storage battery 4a side (charging operation described later). The DC / DC converter 5 also converts the DC voltage V3 input from the battery 4 or the lead storage battery 4a side into a predetermined DC voltage V4 and outputs it to the AC / DC converter 6 (discharging operation described later).

[0063] In the case of the DC / DC converter 5, since it is embedded in the charging system 3, it is configured so that the charging operation is prioritized over the discharging operation in terms of its structure and function as described later. Therefore, the structure and function will be mainly described with the charging operation as the main focus.

[0064] like Figure 1 As shown in the figure below, the DC / DC converter 5 includes a converter mechanism 16 including an output current sensor 10, a primary side first voltage sensor 11, a primary side second voltage sensor 12, a secondary side voltage sensor 13, a bidirectional insulated LLC resonant circuit 15, etc., and a controller 17 that controls the converter mechanism 16.

[0065] The output current sensor 10 is a Hall element type sensor, and is provided at a predetermined position of the primary side main line 36 and the secondary side main line 54 described later. Figure 2 As shown, the output current sensor 10 directly measures the current (output current Iout) flowing through the primary side input / output terminal 30 and the secondary side input / output terminal 50 and outputs it to the controller 17 .

[0066] The primary-side first voltage sensor 11 is provided at a predetermined position of the primary-side main line 36, and directly measures the voltage (primary-side voltage Vin) of the high voltage acting between the pair of primary-side main lines 36, 36, and outputs it to the controller 17. The primary-side second voltage sensor 12 is provided at a predetermined position between the primary-side main line 36 on the negative side and the connecting line 38, and directly measures the voltage (primary-side half voltage Vin (LO)) of the intermediate voltage as the low voltage acting between the primary-side main line 36 and the connecting line 38, and outputs it to the controller 17.

[0067] The secondary voltage Vout sensor 13 is provided at a predetermined position of the secondary main line 54 , directly measures the voltage (secondary voltage Vout) of the high voltage acting between the pair of secondary main lines 54 , 54 , and outputs it to the controller 17 .

[0068] Based on these measured values, the controller 17 outputs a driving voltage to the 10 switching elements S1 to S10 (the first to tenth switching elements S1 to S10) of the bidirectional insulated LLC resonant circuit 15 to perform on / off control, that is, the energized state (on) and the non-energized state (off) of these switching elements S1 to S10 are switched at a predetermined timing.

[0069] (Bidirectional Insulated LLC Resonant Circuit)

[0070] Figure 2 2 shows a bidirectional insulated LLC resonant circuit 15 (hereinafter also referred to as a converter circuit 15). The converter circuit 15 generally includes a transformer 20, a primary side circuit 21 located on the primary side of the transformer 20, a secondary side circuit 22 located on the secondary side of the transformer 20, and an LLC circuit 23 located between the transformer 20 and the primary side circuit 21.

[0071] The primary side circuit 21 has a pair of primary side input / output terminals 30 (primary side input / output terminal pair) and six primary side switching elements S1 to S6. The secondary side circuit 22 has a pair of secondary side input / output terminals 50 (secondary side input / output terminal pair) and four secondary side switching elements S7 to S10. With the converter circuit 15 having such a structure, the DC / DC converter 5 is configured to be able to perform a charging operation in which a DC voltage is input to the primary side input / output terminal 30 and output from the secondary side input / output terminal 50, and a discharging operation in which a DC voltage is input to the secondary side input / output terminal 50 and output from the primary side input / output terminal 30.

[0072] The primary side switching elements S1 to S6 and the secondary side switching elements S7 to S10 are composed of well-known MOSFETs having gate, source, and drain terminals. They are turned on by applying a predetermined driving voltage to the gate terminal. The primary side switching elements S1 to S6 and the secondary side switching elements S7 to S10 are configured so that the current direction in the on state is from the positive electrode side to the negative electrode side. The primary side switching elements S1 to S6 and the secondary side switching elements S7 to S10 include a freewheeling diode 24 connected in anti-parallel.

[0073] The transformer 20 has a primary coil 20a and a secondary coil 20b. N1 is the number of turns of the primary coil 20a, and N2 is the number of turns of the secondary coil 20b. N1:N2 represents the turn ratio. In the case of the converter circuit 15 in this embodiment, N1:N2 is 1:1. However, the turn ratio can be changed according to the specification of the operating range of the input and output voltages.

[0074] The primary circuit 21 includes a first branch 31 , a second branch 32 , a third branch 33 , a fourth branch 34 , a fifth branch 35 , a pair of primary main lines 36 , 36 , a pair of bypass lines 37 , 37 , and a connecting line 38 .

[0075] In the first branch 31, two primary-side switching elements S3 and S4 are arranged in series. In the second branch 32, four primary-side switching elements S5, S1, S2, and S6 are connected in series. For ease of explanation, it is assumed that two element pairs 25 consisting of two primary-side switching elements (S5, S1 and S2, S6) connected in series are arranged in series.

[0076] In the third branch 33, two primary side capacitors C1 and C2 are arranged in series. The capacitances of these primary side capacitors C1 and C2 are the same. In the fourth branch 34, an intermediate capacitor C3 is arranged. In the fifth branch 35, two diodes D1 and D2 are arranged in series. These diodes D1 and D2 are arranged in a manner that the current flow direction is from the negative electrode side to the positive electrode side.

[0077] The first branch 31, the second branch 32, and the third branch 33 are connected in parallel between a pair of primary-side main lines 36, 36. The primary-side input / output terminal 30 is arranged at one end of these primary-side main lines 36, 36. The third branch 33, the second branch 32, and the first branch 31 are arranged in order from the primary-side input / output terminal 30 side.

[0078] A pair of bypass lines 37, 37 are connected in parallel to the portion between the primary-side switching elements (S5, S1 and S2, S6) included in the element pairs 25, 25 in the second branch 32. Moreover, the fourth branch 34 and the fifth branch 35 are connected in parallel between these bypass lines 37, 37. The connecting line 38 is connected to the portion between the two diodes D1, D2 in the fifth branch 35 and the portion between the two primary-side capacitors C1, C2 in the third branch 33 (intermediate voltage output portion 43).

[0079] The positive-side end of the primary-side coil 20a and the portion between the two element pairs 25, 25 in the second arm 32 are connected via the primary-side upper relay wiring 45. Furthermore, the negative-side end of the primary-side coil 20a and the portion between the two primary-side switching elements S3, S4 in the first arm 31 are connected via the primary-side lower relay wiring 46.

[0080] On the primary-side upper relay wiring 45, a primary-side resonant capacitor Cr and a primary-side resonant inductor Lr (leakage inductance) are arranged in series in this order from the second arm 32 side. An exciting inductor Lm is connected in parallel to the primary-side coil 20a.

[0081] The magnetizing inductance Lm may be an inductance generated by the main magnetic flux of the transformer 20. The LLC circuit 23 is constituted by the primary side resonant inductance Lr, the magnetizing inductance Lm, and the primary side resonant capacitor Cr. The primary side resonant inductance Lr may be a parasitic element of the transformer 20.

[0082] The secondary side circuit 22 has a sixth branch 51 , a seventh branch 52 , an eighth branch 53 , and a pair of secondary side main lines 54 , 54 .

[0083] In the sixth branch 51, two secondary-side switching elements S7 and S8 are arranged in series, and in the seventh branch 52, two secondary-side switching elements S9 and S10 are arranged in series. In the eighth branch 53, a secondary-side capacitor C4 is arranged. The sixth branch 51, the seventh branch 52, and the eighth branch 53 are connected in parallel between a pair of secondary-side main lines 54 and 54. A secondary-side input-output terminal 50 is arranged at one end of these secondary-side main lines 54 and 54. The eighth branch 53, the seventh branch 52, and the sixth branch 51 are arranged in order from the secondary-side input-output terminal 50 side.

[0084] The end of the secondary coil 20b on the positive side is connected to the portion between the two secondary switching elements S7 and S8 in the sixth arm 51 via the secondary upper relay wiring 57. Furthermore, the end of the secondary coil 20b on the negative side is connected to the portion between the two secondary switching elements S9 and S10 in the seventh arm 52 via the secondary lower relay wiring 58.

[0085] During the charging operation, the primary voltage Vin is applied to the pair of primary main lines 36, 36. Therefore, the primary voltage Vin is also applied to each of the first arm 31, the second arm 32, and the third arm 33.

[0086] Furthermore, during the charging operation, a voltage (transformer voltage VTR) acts between the primary-side upper relay wiring 45 and the primary-side lower relay wiring 46, and a current (transformer current ITR) flows through the primary-side upper relay wiring 45. Thus, a secondary-side voltage Vout is applied to the pair of secondary-side main lines 54, 54, and a current (output current Iout) flows through the secondary-side input / output terminal 50.

[0087] (Charging control by the controller)

[0088] Next, the control during the charging operation performed by the controller 17 will be described (the control during the discharging operation will be described later).

[0089] Figure 3 2 is a control block diagram of the controller 17 during the charging operation. Figure 4 2 shows a table that summarizes the switch operation control information that the controller 17 has. Figure 5 The resonance curve of the LLC circuit 23 is shown in FIG. Figure 6 2 shows an example of various waveforms during charging operation and a switching operation pattern (a timing chart of switching operation).

[0090] like Figure 5 As indicated by the arrow line in FIG. 1 , the LLC circuit 23 generally adjusts the output voltage within the frequency operating range between the lower limit value fm and the upper limit value fr of the resonant frequency. Therefore, in the LLC circuit 23 of the DC / DC converter 5, the operating frequency can also be set within this range. However, the operating frequency of the LLC circuit 23 is as follows: Figure 5 As indicated by the circle in FIG. 2 , it is preferably fixed to the upper limit value fr of the resonance frequency or a value in the vicinity thereof. By doing so, the magnetizing inductance Lm can be reduced, and thus the transformer 20 can be miniaturized.

[0091] Therefore, in the controller 17, the output current Iout is controlled according to the required output voltage in a state where the operating frequency of the LLC circuit 23 is fixed at the upper limit value fr of the resonant frequency or a value in the vicinity thereof. The lower limit value fm and the upper limit value fr of the resonant frequency are determined by the performance of the primary side resonant capacitor Cr, the primary side resonant inductor Lr, and the excitation inductor Lm constituting the LLC circuit 23.

[0092] Although not shown in the figure, the controller 17 includes hardware such as a processor and a memory and software such as a control program and data installed in the memory. Figure 3 As shown in the figure, it has a configuration including a voltage balance regulator 17a, a current regulator 17b, a control unit 17c, a drive circuit 17d, and the like.

[0093] The voltage balance regulator 17a outputs a first parameter da* and a second parameter db* used in setting the duty ratio in PWM control to the control unit 17c based on the primary side voltage Vin input from the primary side first voltage sensor 11 and the primary side half voltage Vin(LO) input from the primary side second voltage sensor 12.

[0094] The current regulator 17b outputs the reference parameter dctl* (equivalent to the command value of the duty cycle) used when setting the duty cycle in PWM control to the control unit 17c based on the primary side voltage Vin, the secondary side voltage Vout input from the secondary side voltage sensor 13, the output current Iout input from the output current sensor 10 and the command value of the output current Iout (output current command value).

[0095] The control unit 17c receives the primary side voltage Vin, the secondary side voltage Vout, and the phase angle used in the phase shift together with the first parameter da*, the second parameter db*, and the reference parameter dctl*. The control unit 17 c has predetermined switching operation control information regarding the switching operation of the converter circuit 15 .

[0096] Figure 4 A table summarizing the switch action control information is shown in FIG. Figure 4 (a) is a table summarizing the switch action control information during charging action. Figure 4 (b) is a table that summarizes the switch operation control information during the discharge operation. The switch operation control information is set based on the magnitude relationship of the DC voltage input and output to the converter circuit 15, and includes information related to PWM control and phase shift.

[0097] During the charging operation, the first to fourth charging voltage ranges are divided into four charging voltage ranges according to the magnitude relationship between the primary side voltage Vin (input voltage) and the secondary side voltage Vout (output voltage) of the converter circuit 15, and switch operation control information (first to fourth charging switch operation control information) is set for each of these charging voltage ranges. According to these first to fourth charging switch operation control information, the ninth and tenth switch elements S9 and S10 of the secondary side circuit 22 are always turned off in all charging voltage ranges.

[0098] During the discharge operation, the first and second discharge voltage ranges are divided according to the magnitude relationship between the secondary voltage Vout (input voltage) and the primary voltage Vin (output voltage) of the converter circuit 15, and switch operation control information (first and second discharge switch operation control information) is set for each of these discharge voltage ranges. According to these first and second discharge switch operation control information, the first, second, fifth and sixth switch elements S1, S2, S5, S6 of the primary circuit 21 are always turned off in all discharge voltage ranges.

[0099] The first charging voltage range is when the secondary voltage Vout exceeds the primary voltage Vin. According to the first charging switching operation control information, in the first charging voltage range, the full-bridge control method is used, and PWM control is performed in the switching operation of each switching element S1 to S8.

[0100] The seventh and eighth switching elements S7 and S8 of the secondary circuit 22 are phase-shifted. Specifically, the switching operation patterns of the seventh and eighth switching elements S7 and S8 are shifted by a phase angle of Treatment (see Figure 7 ). As a result, ZVS (Zero Voltage Switching) can be performed even at high voltage.

[0101] The second charging voltage range is when the secondary side voltage Vout is less than the primary side voltage Vin and exceeds 1 / 2 of the primary side voltage Vin. According to the second charging switch action control information, in the second charging voltage range, the control method uses the full-bridge method in the same way as the first charging switch action control information, and PWM control is performed in the switching action of each switching element S1 to S8. The output voltage is not high, so ZVS can be performed. Therefore, unlike the first charging switch action control information, no phase shift is performed in the secondary side circuit 22.

[0102] The third charging voltage range is the case where the secondary side voltage Vout is less than 1 / 2 of the primary side voltage Vin and exceeds 1 / 4 of the primary side voltage Vin. According to the third charging switch action control information, within the third charging voltage range, the third switch element S3 of the primary side circuit 21 is always turned off, and the fourth switch element S4 is always turned on, and the half-bridge method is used in the control method, and PWM control is performed in the other switch elements S1, S2, S5 to S8.

[0103] The fourth charging voltage range is when the secondary side voltage Vout is less than 1 / 4 of the primary side voltage Vin. According to the fourth charging switch action control information, in the fourth charging voltage range, the control method uses the primary side phase shift method. That is, the fifth and sixth switching elements S5 and S6 of the primary side circuit 21 are always turned off, while the third and fourth switching elements S3 and S4 are phase shifted, and PWM control is performed in the switching action of the first to fourth switching elements S1 to S4.

[0104] Based on the first to fourth charging switch action control information, the control unit 17c changes the switching action modes of the primary side switch elements S1 to S6 and the secondary side switch elements S7 and S8 in the charging action, and outputs a specified control signal to the drive circuit 17d (described later during the discharge action).

[0105] like Figure 3 As shown, the PWM frequency TPWM and the dead time Td are input to the drive circuit 17d together with the control signal. Based on these input information, the drive circuit 17d outputs the drive voltage to the first to tenth switching elements S1 to S10. As a result, the converter mechanism 16 operates, and the DC / DC converter 5 performs the required charging operation.

[0106] (Specific example of switch operation control during charging operation)

[0107] Figure 6 2 exemplifies various waveforms within the second charging voltage range and switching operation patterns of the switching elements S1 to S6 in the primary-side circuit 21 .

[0108] Figure 6 The waveform shown in the upper part is a triangle wave used in PWM control. Figure 6 The time chart shown in the middle is the switching operation mode of each switching element S1 to S6 corresponding to the PWM control. Figure 6 The waveform shown in the lower part of is a schematic diagram of the waveform of the transformer voltage VTR obtained according to these switching action modes.

[0109] The period of the triangular wave is the switching frequency TSW. The first parameter da* sets the PWM signal of the pulse width corresponding to the period TA during which the first and fourth switching elements S1 and S4 are turned on based on the triangular wave. The second parameter db* sets the PWM signal of the pulse width corresponding to the period TB during which the second and third switching elements S2 and S3 are turned on based on the triangular wave. The period of the transformer voltage VTR is the PWM frequency TPWM.

[0110] The third parameter dc* and the fourth parameter dd* are obtained by the following equations using the reference parameter dctl*, the first parameter da*, and the second parameter db*.

[0111] The third parameter dc*=reference parameter dctl*+first parameter da*

[0112] Fourth parameter dd*=reference parameter dctl*+second parameter db*

[0113] Here, the first parameter da*, the second parameter db*, and the reference parameter dctl* are all greater than or equal to 0 and less than or equal to 0.5. That is, the setting range of the duty ratio is greater than or equal to 0% and less than or equal to 50%.

[0114] The third parameter dc* sets a PWM signal of a pulse width corresponding to a period TC during which the fifth switching element S5 is turned on by the triangular wave. The fourth parameter dd* sets a PWM signal of a pulse width corresponding to a period TD during which the sixth switching element S6 is turned on by the triangular wave.

[0115] By performing such PWM control, the positive and negative waveforms of the transformer voltage VTR can be made equal, thereby suppressing the phenomenon of DC bias.

[0116] exist Figure 6 In the example of , the duty ratio is set to the maximum (first parameter da*=second parameter db*=0.5, dc*=dd*). Thus, period TA=period TB, period TC=period TD, and the transformer voltage VTR changes at 1 / 2 of the primary voltage Vin, and the voltage waveform input to the LLC circuit 23 can be maintained as a sine wave. Even if the secondary voltage Vout exceeds 1 / 2 of the primary voltage Vin, that is, the primary half voltage Vin (LO), ZVS can be performed.

[0117] The balance of the charging voltages of the two primary side capacitors C1 and C2 can also be stabilized. Furthermore, the transformer current ITR can be controlled by changing the reference parameter dctl*.

[0118] Figure 7 2 shows the switching operation mode of each switching element S1 to S8 in the primary side circuit 21 and the secondary side circuit 22 in the first charging voltage range. Figure 6 The switching operation patterns of the switching elements S1 to S6 in the primary side circuit 21 within the second charging voltage range shown in FIG. 2 are the same.

[0119] In the first charging voltage range, unlike the second charging voltage range, the seventh and eighth switching elements S7 and S8 of the secondary circuit 22 are phase-shifted. Thus, in these seventh and eighth switching elements S7 and S8, the phase is shifted from the switching operation mode of the other switching elements S1 to S6 by a phase angle different from that in the second charging voltage range.

[0120] Fig. 8A and Figure 8B Shown in Figure 7 Schematic diagram of the current path of the converter circuit 15 in the first to sixth states st1 to st6 shown in the upper part of FIG. In the first charging voltage range, the current path changes in the order of the first state st1, the second state st2, the third state st3, the second state st2, the fourth state st4, the fifth state st5, the sixth state st6, and the fifth state st5. Moreover, this change is repeated.

[0121] In the first state st1, the first, fourth, and eighth switch elements S1, S4, and S8 are turned on, and the second, third, fifth to seventh switch elements S2, S3, S5 to S7 are turned off. Fig. 8A As indicated by the dotted arrow line in the figure above, in the primary side circuit 21, a current flows out from the intermediate voltage output portion 43, and thus the transformer current ITR flows through the primary side coil 20a of the transformer 20 (from the positive side to the negative side). At this time, the primary side half voltage Vin (LO) acts on the LLC circuit 23.

[0122] Then, in the secondary side circuit 22, as shown in FIG. Fig. 8A As indicated by the dotted arrow line in the figure above, the current flows through the secondary coil 20b of the transformer 20 (from the negative side to the positive side), and flows through the path inside the secondary circuit 22 in the order of the eighth switching element S8 and the tenth switching element S10 (flying diode 24). That is, at this time, the current does not flow from the converter circuit 15 to the outside.

[0123] In the second state st2, the first, fourth, and seventh switch elements S1, S4, and S7 are turned on, and the second, third, fifth, sixth, and eighth switch elements S2, S3, S5, S6, and S8 are turned off. Fig. 8A As indicated by the dashed arrow line in the figure, the current path in the primary side circuit 21 is the same as that in the first state st1.

[0124] On the other hand, in the secondary side circuit 22, as Fig. 8A As indicated by the dotted arrow line in the middle figure, the current flows in from the secondary input / output terminal 50 (negative side), passes through the tenth switching element S10 (flying diode 24), the secondary coil 20b of the transformer 20 (from the negative side to the positive side), and the seventh switching element S7 (flying diode 24) in this order, and is output from the secondary input / output terminal 50 (positive side). Therefore, at this time, the current flows from the converter circuit 15 to the outside.

[0125] In the third state st3, the first, fourth, fifth, and seventh switch elements S1, S4, S5, and S7 are turned on, and the second, third, sixth, and eighth switch elements S2, S3, S6, and S8 are turned off. Fig. 8A As indicated by the dotted arrow line in the figure below, in the primary side circuit 21, the current flows in from the primary side input / output terminal 30 (positive side), thereby the transformer current ITR flows through the primary side coil 20a of the transformer 20 (from the positive side to the negative side), and flows out from the primary side input / output terminal 30 (negative side). At this time, the primary side voltage Vin acts on the LLC circuit 23.

[0126] In the secondary side circuit 22, as Fig. 8A As indicated by the dashed arrow line in the lower figure, the current path is the same as in the second state st2. Therefore, at this time, the current flows from the converter circuit 15 to the outside.

[0127] After the third state st3, the second state st2 is entered again, and then the fourth state st4 is entered.

[0128] In the fourth state st4, the second, third, and seventh switch elements S2, S3, and S7 are turned on, and the first, fourth to sixth, and eighth switch elements S1, S4 to S6, and S8 are turned off. Figure 8B As indicated by the dotted arrow line in the figure above, in the primary side circuit 21, a current flows in from the primary side input / output terminal 30 (positive side) due to the primary side voltage Vin, and thereby the transformer current ITR flows through the primary side coil 20a of the transformer 20 (from the negative side to the positive side), and flows into the intermediate voltage output portion 43. As a result, the primary side capacitor C2 (negative side) is charged.

[0129] Then, in the secondary side circuit 22, as shown in FIG. Figure 8B As indicated by the dotted arrow line in the figure above, the current flows through the secondary coil 20b of the transformer 20 (from the positive side to the negative side), and flows through the path inside the secondary circuit 22 in the order of the ninth switching element S9 (flying diode 24) and the seventh switching element S7. That is, at this time, the current does not flow from the converter circuit 15 to the outside.

[0130] In the fifth state st5, the second, third, and eighth switch elements S2, S3, and S8 are turned on, and the first, fourth to seventh switch elements S1, S4 to S7 are turned off. Figure 8B As indicated by the dashed arrow line in the figure, the current path in the primary side circuit 21 is the same as that in the fourth state st4.

[0131] On the other hand, in the secondary side circuit 22, as Figure 8BAs indicated by the dotted arrow line in the middle figure, the current flows in from the secondary input / output terminal 50 (negative side), passes through the eighth switching element S8 (flying diode 24), the secondary coil 20b of the transformer 20 (from the positive side to the negative side), and the ninth switching element S9 (flying diode 24) in this order, and is output from the secondary input / output terminal 50 (positive side). Therefore, at this time, the current flows from the converter circuit 15 to the outside.

[0132] In the sixth state st6, the second, third, sixth, and eighth switch elements S2, S3, S6, and S8 are turned on, and the first, fourth, fifth, and seventh switch elements S1, S4, S5, and S7 are turned off. Figure 8B As indicated by the dotted arrow line in the figure below, in the primary side circuit 21, current flows into the primary side input / output terminal 30 (positive side) due to the primary side voltage Vin, thereby the transformer current ITR flows through the primary side coil 20a of the transformer 20 (from the negative side to the positive side) and flows out from the primary side input / output terminal 30 (negative side).

[0133] In the secondary side circuit 22, as Figure 8B As indicated by the dashed arrow line in the lower figure, the current path is the same as that in the fifth state st5. Therefore, at this time, the current flows from the converter circuit 15 to the outside.

[0134] After the sixth state st6, the fifth state st5 is entered again. After that, the first state st1 is entered again, and thereafter, the second state st2 and the above-mentioned states are repeated.

[0135] Thus, when the DC voltage output during charging operation is larger than the primary half voltage Vin(LO), the controller 17 controls the duty ratio and causes the primary voltage Vin and the primary half voltage Vin(LO) to be switched and applied to the LLC circuit 23 .

[0136] Therefore, as described above, the positive and negative waveforms of the transformer voltage VTR can be made equal, so that the phenomenon of DC bias magnetization can be suppressed. If the duty ratio is maximized, the voltage waveform input to the LLC circuit 23 can be maintained in a sinusoidal shape.

[0137] Fig. 9 2 , the switching operation patterns of the switching elements S1 , S2 , S5 , and S6 in the converter circuit 15 and the primary-side circuit 21 and the secondary-side circuit 22 within the third charging voltage range are exemplified.

[0138] In the third charging voltage range, the third switch element S3 is always turned off, and the fourth switch element S4 is always turned on. Fig. 9 The circuit shown in (a) is equivalent.

[0139] In this case, combined with the above example, it becomes as follows Fig. 9 The switching operation mode and the waveform of the transformer voltage VTR are shown in (b). Fig. 9 The equivalent circuit of (a) is a half-bridge LLC circuit. Generally speaking, the half-bridge LLC circuit is a circuit for small capacitors, but in the present invention, within the output voltage range during the operation, as shown in FIG. Figure 4 As shown in (a), the output voltage operation range is set to Vin / 4 to Vin / 2 for control.

[0140] Fig.10 Schematic diagram of the equivalent circuit of the converter circuit 15 and its current path in the fourth charging voltage range is shown in . In the fourth charging voltage range, the second and fifth states st2 and st5 in the first charging voltage range are substantially repeated while performing phase shift in the third and fourth switching elements S3 and S4.

[0141] (Discharge control by the controller)

[0142] Next, the control performed by the controller 17 during the discharge operation will be described.

[0143] In this converter circuit 15, there is no resonant capacitor in the secondary side circuit 22. However, all the primary side switching elements S1 to S6 are turned off, and their freewheeling diodes 24 are used. In this state, by switching the secondary side switching elements S7 to S10, the converter circuit 15 can perform a discharge operation of inputting power from the secondary side and outputting power from the primary side.

[0144] However, in this case, since only a square wave is applied to the excitation inductance Lm, it cannot resonate with the primary side resonant capacitor Cr. Therefore, it becomes a normal series resonance type operation with only the primary side resonant capacitor Cr and the primary side resonant inductance Lr as the resonant elements during discharge. Therefore, the operating range of the input and output power during discharge is basically limited by the turns ratio of the transformer 20. That is, the secondary side voltage Vout is the same as the primary side voltage Vin.

[0145] However, during discharge, the primary side voltage Vin may be higher than the secondary side voltage Vout. In this regard, a voltage boost operation can be achieved by performing phase shift in the third and fourth switching elements S3 and S4 of the primary side circuit 21. Therefore, in the DC / DC converter 5, the primary side voltage Vin can be made higher than the secondary side voltage Vout. In addition, during discharge, the AC / DC converter 6 can perform constant control of the AC output voltage, so there is no need to perform PWM control that changes the duty cycle.

[0146] Therefore, during the discharge operation, the primary side voltage Vin (output voltage) and the secondary side voltage Vout (input voltage) are divided into the first and second discharge voltage ranges, such as Figure 4 As shown in (b) of FIG. 1 , switch operation control information (first and second discharge switch operation control information) is set for each of these discharge voltage ranges.

[0147] Based on the first and second discharge switching operation control information, all the switching elements S7 to S10 of the secondary side circuit 22 are subjected to PWM control with the duty ratio fixed at 50% in all discharge voltage ranges.

[0148] The first discharge voltage range is when the secondary voltage Vout is equal to the primary voltage Vin. According to the first discharge switch operation control information, in the first discharge voltage range, the full-bridge control method is used, and all switch elements S1 to S6 of the primary circuit 21 are always turned off.

[0149] The second discharge voltage range is when the primary side voltage Vin is higher than the secondary side voltage Vout. According to the second discharge switching operation control information, within the second discharge voltage range, the first, second, fifth, and sixth switch elements S1, S2, S5, and S6 of the primary side circuit 21 are always turned off, and phase shift is performed in the third and fourth switch elements S3 and S4.

[0150] Fig.11 2 , the switching operation patterns of the switching elements S3 , S4 , and S7 to S10 in the primary side circuit 21 and the secondary side circuit 22 in the second discharge voltage range are exemplified. Fig. 12A and Fig. 12B Shown in Fig.11 Schematic diagram of the current path of the converter circuit 15 in the first to fourth states st1 to st4 shown in the upper part. In the second discharge voltage range, the current path changes in the order of the first state st1, the second state st2, the third state st3, and the fourth state st4. And this change is repeated.

[0151] In addition, in the first discharge voltage range, there is no second state st2 and fourth state st4 associated with phase shift. Therefore, only the first state st1 and the third state st3 are repeated, and thus detailed description thereof is omitted.

[0152] In the first state st1, the seventh, tenth and fourth switch elements S7, S10 and S4 are turned on, and the eighth, ninth and third switch elements S8, S9 and S3 are turned off. Fig. 12AAs indicated by the dotted arrow line in the above figure, in the secondary side circuit 22, current flows in from the secondary side input / output terminal 50 (positive side), thereby flowing through the secondary side coil 20b of the transformer 20 (from the positive side to the negative side), and flows out from the secondary side input / output terminal 50 (negative side).

[0153] Then, in the primary side circuit 21, as Fig. 12A As indicated by the dotted arrow line in the figure above, the current flows in from the primary side input / output terminal 30 (negative side), passes through the fourth switching element S4 (flying diode 24), the primary side coil 20a of the transformer 20 (from the negative side to the positive side), the first and fifth switching elements S1 and S5 (flying diode 24) in this order, and is output from the primary side input / output terminal 30 (positive side). Therefore, at this time, the current flows from the converter circuit 15 to the outside.

[0154] In the second state st2, the seventh, tenth and third switch elements S7, S10 and S3 are turned on, and the eighth, ninth and fourth switch elements S8, S9 and S4 are turned off. Fig. 12A As indicated by the dashed arrow line in the lower figure, the current path in the secondary side circuit 22 is the same as that in the first state st1.

[0155] On the other hand, in the primary side circuit 21, as Fig. 12A As indicated by the dotted arrow line in the figure below, the current flows through the primary side coil 20a of the transformer 20 (from the negative side to the positive side), and flows through the path inside the primary side circuit 21 in the order of the first and fifth switching elements S1, S5 (flying diode 24), and the third switching element S3. That is, at this time, the current does not flow from the converter circuit 15 to the outside.

[0156] In the third state st3, the eighth, ninth and third switch elements S8, S9 and S3 are turned on, and the seventh, tenth and fourth switch elements S7, S10 and S4 are turned off. Fig. 12B As indicated by the dotted arrow line in the above figure, in the secondary side circuit 22, current flows in from the secondary side input / output terminal 50 (positive side), thereby flowing through the secondary side coil 20b of the transformer 20 (from the negative side to the positive side), and flows out from the secondary side input / output terminal 50 (negative side).

[0157] Then, in the primary side circuit 21, as Fig. 12BAs indicated by the dotted arrow line in the figure above, the current flows in from the primary side input / output terminal 30 (negative side), passes through the sixth and second switching elements S6, S2 (flying diode 24), the primary side coil 20a of the transformer 20 (from the positive side to the negative side), and the third switching element S3 (flying diode 24) in this order, and is output from the primary side input / output terminal 30 (positive side). Therefore, at this time, the current flows from the converter circuit 15 to the outside.

[0158] In the fourth state st4, the eighth, ninth and fourth switch elements S8, S9 and S4 are turned on, and the seventh, tenth and third switch elements S7, S10 and S3 are turned off. Fig. 12B As indicated by the dashed arrow line in the lower figure, the current path in the secondary side circuit 22 is the same as that in the third state st3.

[0159] Then, in the primary side circuit 21, as Fig. 12B As indicated by the dotted arrow line in the figure below, the current flows through the primary side coil 20a of the transformer 20 (from the positive side to the negative side), and flows through the path inside the primary side circuit 21 passing through the fourth switching element, the sixth switching element S4, S6, and the second switching element S2 (flying diode 24) in this order. That is, at this time, the current does not flow from the converter circuit 15 to the outside.

[0160] After the fourth state st4, the state returns to the first state st1 again, and thereafter, the second state st2 and the above-mentioned states are repeated.

[0161] <Effect Verification>

[0162] The effects of the DC / DC converter 5 were verified by simulation. First, the stability of the primary side half voltage Vin (LO) during the charging operation was verified.

[0163] Fig.13 The verification results are shown in . Fig.13 The upper graph of is a graph showing the time-dependent change in the voltage of the two primary-side capacitors C1 and C2 at the time of startup. Fig.13 The middle curve of is the time variation of the corresponding input voltage (primary side voltage Vin). Fig.13 The lower graph of is the time-dependent change of the output current Iout corresponding thereto.

[0164] It was confirmed that the voltage difference between the two primary side capacitors C1 and C2 at the start of startup was 200 V, but the difference immediately converged to 0, that is, the primary side half voltage Vin(LO). In addition, the ripple of the input voltage is caused by the output from the PFC circuit.

[0165] Next, the results of simulations for two cases of charging actions with different input and output voltages are shown. Case 1 is a case where the input voltage (primary side voltage Vin) is 400V and the output voltage (secondary side voltage Vout) is 300V (second charging voltage range). Case 2 is a case where the input voltage (primary side voltage Vin) is 400V and the output voltage (secondary side voltage Vout) is 450V (first charging voltage range). The output power is 4kW in both cases.

[0166] exist Fig.14 , the temporal changes of various main factors such as the transformer voltage VTR in each simulation of Case 1 and Case 2 are shown side by side in a comparable manner.

[0167] like Fig.14 As shown, it is confirmed that the step-up and step-down operation can be realized with a constant input voltage, and charging can be performed with a constant power. Therefore, according to the technology to be disclosed, the supported power conversion range can be effectively expanded on both the charging side and the discharging side, and a small and efficient power conversion device can be realized.

[0168] <Modification of Bidirectional Insulated LLC Resonance Circuit>

[0169] Fig.15 2 shows a modified example (second converter circuit 15B) of the above-mentioned converter circuit 15. The second converter circuit 15B is also provided with an LLC circuit on the secondary side circuit 22 side, and is different from the above-mentioned converter circuit 15 in this respect. Other aspects are the same, so the same symbols are used for the same structure and their description is omitted.

[0170] That is, the second converter circuit 15B further includes an LLC circuit (secondary-side LLC circuit 60) (so-called CLLC converter) located between the transformer 20 and the secondary-side circuit 22. Specifically, in the secondary-side LLC circuit 60, a secondary-side resonant capacitor 61 and a secondary-side resonant inductor 62 (leakage inductance) are sequentially arranged in series from the sixth arm 51 side on the secondary-side upper relay wiring 57. A secondary-side magnetizing inductor may be connected in parallel with the secondary-side coil 20b.

[0171] The secondary-side LLC circuit 60 is formed by the secondary-side resonant capacitor 61 and the secondary-side resonant inductor 62. Therefore, according to the second converter circuit 15B, the power support range during the discharge operation can be further expanded.

[0172] <Other Methods of Bidirectional Insulated LLC Resonant Circuit>

[0173] Fig.161 shows another embodiment of the converter circuit 15 (third converter circuit 15C). In the third converter circuit 15C, the configurations of the converter circuit 15 and the primary side circuit 21 are different. The secondary side circuit of the third converter circuit 15C is the same as the secondary side circuit 22 of the converter circuit 15, and therefore the same reference numerals are used for the same configurations and the description thereof is omitted.

[0174] The primary side circuit 21 of the third converter circuit 15C also has a primary side input-output terminal 30 and six primary side switching elements S1 to S6, as well as a third branch 33 having two primary side capacitors C1 and C2 configured in series and a first branch 31 having two primary side switching elements S3 and S4 configured in series, and is the same as the above-mentioned converter circuit 15 in these respects.

[0175] In addition to these, the primary side circuit 21 of the third converter circuit 15C further includes a second branch 32 in which two primary side switching elements S5 and S6 are arranged in series. Furthermore, the first branch 31, the second branch 32, and the third branch 33 are connected in parallel between a pair of primary side main lines 36 and 36 having primary side input / output terminals 30 arranged at one end.

[0176] Furthermore, a connection line 38 is connected between the two primary-side switching elements S5 and S6 in the second arm 32 and between the two primary-side capacitors C1 and C2 in the third arm 33. On the connection line 38, the two primary-side switching elements S1 and S2 are arranged in series so that the current-carrying directions of both sides face inward.

[0177] The control contents of the third converter circuit 15C are the same as those of the above-mentioned converter circuit 15. That is, the control method of the third converter circuit 15C, the switching operation pattern of each switching element S1 to S10, and the like are the same as those of the above-mentioned converter circuit 15.

[0178] Although not shown in the figure, the third converter circuit 15C may further include an LLC circuit (secondary-side LLC circuit 60 ) located between the transformer 20 and the secondary-side circuit 22 , similarly to the second converter circuit 15B.

Claims

1. A power conversion device comprising a converter mechanism including a bidirectional insulated LLC resonant circuit and a controller for controlling the converter mechanism, which inputs a DC voltage and converts it into a DC voltage of different magnitude and outputs it, characterized in that: The bidirectional insulated LLC resonant circuit has: A transformer having a primary coil and a secondary coil; A primary side circuit, located on the primary side of the transformer, comprising a primary side input and output terminal pair and six primary side switch elements; A secondary side circuit, located on the secondary side of the transformer, comprising a secondary side input and output terminal pair and four secondary side switch elements; as well as LLC circuit, located between the transformer and the primary side circuit, The power conversion device is configured to be capable of performing a charging operation in which a DC voltage is input to the primary-side input / output terminal pair and outputted from the secondary-side input / output terminal pair, and a discharging operation in which a DC voltage is input to the secondary-side input / output terminal pair and outputted from the primary-side input / output terminal pair. The controller is configured to have switching action control information related to a duty cycle and a phase shift set according to the magnitude relationship between the input and output DC voltages, and to change the respective switching action modes of the primary-side switching element and the secondary-side switching element in the charging action and the discharging action based on the switching action control information.

2. The power conversion device according to claim 1, characterized in that: The primary side circuit further includes an intermediate voltage output portion, wherein the intermediate voltage of the primary side voltage, that is, the primary side half voltage, which is the DC voltage input to the primary side input / output terminal pair, acts on the LLC circuit. When the DC voltage output during the charging operation is larger than the primary side half voltage, the controller controls the duty ratio while switching between the primary side voltage and the primary side half voltage to act on the LLC circuit.

3. The power conversion device according to claim 1 or 2, characterized in that: The primary side circuit has: A first branch having two primary-side switching elements configured in series; A second branch having two element pairs formed by two primary-side switching elements connected in series is configured in series; a third branch having two primary side capacitors configured in series; A fourth branch provided with an intermediate capacitor; a fifth branch having two diodes arranged in series; a pair of primary-side main lines, one end of which is provided with the pair of primary-side input-output terminals, and the first branch, the second branch and the third branch are connected in parallel between the pair of primary-side main lines; a pair of bypass lines connected in parallel between the primary-side switching elements included in the element pairs in the second branch, and the fourth branch and the fifth branch connected in parallel between the pair of bypass lines; as well as a connecting line connected to a portion between the two diodes in the fifth branch and a portion between the two primary-side capacitors in the third branch, The secondary side circuit has: a sixth branch and a seventh branch, wherein two of the secondary-side switch elements are respectively configured in series on the sixth branch and the seventh branch; an eighth branch provided with a secondary side capacitor; and a pair of secondary-side main lines, one end of which is provided with the pair of secondary-side input-output terminals, and the sixth branch, the seventh branch, and the eighth branch are connected in parallel between the pair of secondary-side main lines, The power conversion device also has: A primary-side upper relay wiring connecting an end of the positive electrode side of the primary-side coil to a portion between two of the element pairs in the second branch; A primary-side lower relay wiring connecting an end of the primary-side coil on the negative side to a portion between two of the primary-side switching elements in the first branch; A secondary-side upper relay wiring connecting an end portion of the secondary-side coil on the positive side to a portion between two of the secondary-side switching elements in the sixth branch; as well as The secondary side lower relay wiring connects the negative electrode side end of the secondary side coil to the portion between the two secondary side switching elements in the seventh branch. The LLC circuit includes a primary-side resonant capacitor and a primary-side resonant inductor which are arranged in series on the primary-side upper relay wiring.

4. The power conversion device according to claim 3, characterized in that: The bidirectional insulated LLC resonant circuit further has a secondary-side LLC circuit located between the transformer and the secondary-side circuit.

5. The power conversion device according to claim 1 or 2, characterized in that: The primary side circuit has: A first branch and a second branch, wherein two primary-side switch elements are respectively configured in series on the first branch and the second branch; a third branch having two primary side capacitors configured in series; a pair of primary-side main lines, one end of which is provided with the pair of primary-side input-output terminals, and the first branch, the second branch and the third branch are connected in parallel between the pair of primary-side main lines; as well as a connecting line on which the two primary-side switching elements are arranged in series so that the energization directions of both sides are opposite, and the connecting line is connected to a portion between the two primary-side switching elements in the second branch and a portion between the two primary-side capacitors in the third branch, The secondary side circuit has: a sixth branch and a seventh branch, wherein two of the secondary-side switch elements are respectively configured in series on the sixth branch and the seventh branch; an eighth branch provided with a secondary side capacitor; and a pair of secondary-side main lines, one end of which is provided with the pair of secondary-side input-output terminals, and the sixth branch, the seventh branch, and the eighth branch are connected in parallel between the pair of secondary-side main lines, The power conversion device also has: A primary-side upper relay wiring connecting an end of the positive pole side of the primary-side coil to a portion between two of the primary-side switching elements in the second branch; A primary-side lower relay wiring connecting an end of the primary-side coil on the negative side to a portion between two of the primary-side switching elements in the first branch; A secondary-side upper relay wiring connecting an end portion of the secondary-side coil on the positive side to a portion between two of the secondary-side switching elements in the sixth branch; as well as The secondary side lower relay wiring connects the negative electrode side end of the secondary side coil to the portion between the two secondary side switching elements in the seventh branch. The LLC circuit includes a primary-side resonant capacitor and a primary-side resonant inductor which are arranged in series on the primary-side upper relay wiring.

6. The power conversion device according to claim 5, characterized in that: The bidirectional insulated LLC resonant circuit further has a secondary-side LLC circuit located between the transformer and the secondary-side circuit.

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