Power conversion device

Abstract

A power conversion device (14) has low voltage side terminals (TL1, TL2) and high voltage side terminals (TH1, TH2). This power conversion device is provided with: a step-up operation unit that performs a step-up operation for boosting a voltage input from a low-voltage-side terminal and outputting the boosted voltage to a high-voltage-side terminal; a step-down operation unit that performs a step-down operation that steps down a voltage input from the high-voltage-side terminal and outputs the stepped-down voltage to the low-voltage-side terminal; and a control unit (24) that performs temperature rise control in which the temperature of the object (13) to be heated is raised by causing the step-up operation unit to perform the step-up operation and the step-down operation unit to perform the step-down operation.

Description

Citation of related applications

[0001] This application is based on Japanese Patent Application No. 2022-094503 filed on June 10, 2022, and the contents thereof are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to a power conversion device having a low-voltage side terminal and a high-voltage side terminal. Background Art

[0003] As this type of power conversion device, Patent Document 1 describes a device that boosts the DC voltage of a battery and supplies the voltage to a capacitor. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2018-42341 Summary of the invention

[0005] For example, as a temperature increase control for increasing the temperature of the battery, it is considered to transmit power between the battery and the capacitor. In this case, part of the transmitted power is converted into heat energy, and the converted heat energy is used to increase the temperature of the battery. However, since there is an upper limit to the voltage that can be applied to the battery and the capacitor, there is a possibility that the power increase transmitted in the temperature increase control is limited. As a result, the heat energy used to increase the temperature of the battery may not be sufficiently increased, resulting in a decrease in the efficiency of the temperature increase control.

[0006] The present disclosure has been made in view of the above-mentioned technical problems, and a main object of the present disclosure is to provide a power conversion device capable of improving the efficiency of temperature increase control.

[0007] The present invention discloses an electric power conversion device, which has a low-voltage side terminal and a high-voltage side terminal, and includes: a boost action unit, which performs a boost action, wherein the boost action boosts the voltage input from the low-voltage side terminal and outputs the boosted voltage to the high-voltage side terminal; a step-down action unit, which performs a step-down action, wherein the step-down action steps down the voltage input from the high-voltage side terminal and outputs the step-down voltage to the low-voltage side terminal; and a control unit, which performs temperature increase control, wherein the temperature increase control increases the temperature of the temperature increase object by causing the boost action unit to perform the boost action and causing the step-down action unit to perform the step-down action.

[0008] Different from the present disclosure, as a temperature rise control, it is considered to alternately perform a voltage rise action of raising the voltage input from the low-voltage side terminal and outputting it to the high-voltage side terminal and a voltage drop action of dropping the voltage input from the high-voltage side terminal and outputting it to the low-voltage side terminal. Thus, power is transmitted between the low-voltage side terminal and the high-voltage side terminal. In this case, part of the transmitted power is converted into heat energy and used to increase the temperature of the temperature rise object.

[0009] In order to increase the thermal energy used in the temperature rise of the temperature rise object, it is considered to increase the power transmitted in the temperature rise control. Here, the power that is not converted into thermal energy in the transmitted power is supplied to the low-voltage side terminal or the high-voltage side terminal. In detail, during the period of the boost action, power is supplied to the high-voltage side terminal. As a result, the terminal voltage of the high-voltage side terminal rises. In addition, during the period of the step-down action, power is supplied to the low-voltage side terminal. As a result, the terminal voltage of the low-voltage side terminal rises. In this case, the terminal voltage of at least one of the low-voltage side terminal and the high-voltage side terminal may reach the upper limit voltage of the low-voltage side terminal or the high-voltage side terminal, thereby limiting the increase in the power transmitted in the temperature rise control. As a result, it is possible that the thermal energy used in the temperature rise of the temperature rise object cannot be fully increased, resulting in a decrease in the efficiency of the temperature rise control.

[0010] In view of this, according to the present disclosure, as a temperature rise control, a control is performed in which the boost action unit performs a boost action and the step-down action unit performs a step-down action. In this case, in the high-voltage side terminal, power is supplied from the low-voltage side terminal by a boost action, and on the other hand, power is output to the low-voltage side terminal by a step-down action. In addition, in the low-voltage side terminal, power is supplied from the high-voltage side terminal by a step-down action, and on the other hand, power is output to the high-voltage side terminal by a boost action. Thus, while suppressing the change of the inter-terminal voltage of the low-voltage side terminal and the inter-terminal voltage of the high-voltage side terminal, power is transmitted between the boost action unit and the step-down action unit. Therefore, it is possible to suppress the inter-terminal voltage of the low-voltage side terminal and the high-voltage side terminal from reaching the upper limit voltage during the implementation of the temperature rise control, and to increase the power transmitted in the temperature rise control. As a result, the thermal energy used in the temperature rise of the temperature rise object can be fully increased, and the efficiency of the temperature rise control can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above objects, other objects, features and advantages of the present disclosure will become more apparent with reference to the accompanying drawings and the following detailed description. Figure 1 It is a structural diagram of the vehicle according to the first embodiment. Figure 2 It is a structural diagram of a power conversion device. Figure 3 It is a timing chart showing an example of the voltage boosting operation. Figure 4 This is a diagram showing a current path flowing through the power conversion device during a boost operation. Figure 5 It is a timing chart showing an example of the voltage reduction operation. Figure 6 This is a diagram showing a current path flowing through the power conversion device during a voltage step-down operation. Figure 7 It is a timing chart showing an example of temperature increase control. Figure 8 It is a diagram showing a method of setting a switching frequency. Fig. 9 This is a diagram showing a method of setting the length of the period in mode 2 or mode 4. Fig.10 It is a graph showing the effect of temperature increase control. Fig.11 It is a graph showing the effect of temperature increase control. Fig.12 This is a timing chart showing an example of the voltage step-up operation and the voltage step-down operation according to the second embodiment. Fig.13 It is a diagram showing the path of current flowing through the power conversion device and the ground during the temperature increase control. Fig.14 It is a timing chart showing an example of temperature increase control. Fig.15 It is a diagram showing the effect of suppressing the generation of noise current. Fig.16 It is a configuration diagram of a power conversion device according to a third embodiment. Fig.17 It is a configuration diagram of a power conversion device according to a fourth embodiment. Fig.18 It is a timing chart showing an example of the voltage reduction operation. Fig.19 This is a diagram showing a current path flowing through the power conversion device and the grounding member during the voltage step-down operation. Fig. 20 It is a structural diagram of a power conversion device according to another embodiment. Fig.21 It is a structural diagram of a power conversion device according to another embodiment. Fig. 22 It is a structural diagram of a power conversion device according to another embodiment. DETAILED DESCRIPTION

[0012] <First embodiment> Hereinafter, a first embodiment of the power conversion device of the present disclosure will be described with reference to the accompanying drawings. The power conversion device is installed in a mobile body such as a vehicle, an aircraft, or a ship. In this embodiment, the power conversion device is installed in a vehicle. The vehicle is, for example, a hybrid vehicle including a rotating electric machine and an engine, or an electric vehicle including only a rotating electric machine in the rotating electric machine and the engine.

[0013] like Figure 1 As shown, the vehicle 10 includes a rotating electric machine 11, an inverter 12, a battery 13, a power conversion device 14, and a heat transfer unit 15. The rotating electric machine 11 is connected to the drive wheel or the engine as the vehicle host via a power split mechanism not shown. The rotating electric machine 11 is connected to the inverter 12 and plays the role of the vehicle host. The inverter 12 is a three-phase inverter and is connected to the battery 13 (for example, a lithium-ion secondary voltage or a nickel-hydrogen secondary battery). For example, the rated voltage of the battery 13 is 600V to 800V.

[0014] The battery 13 is connected to an external charger 16 provided outside the vehicle 10 via the power conversion device 14. The external charger 16 is, for example, a DC fast charger. When the battery 13 is connected to the external charger 16 via the power conversion device 14, the battery 13 is charged using the DC power input from the external charger 16. For example, the charging voltage of the external charger 16 is 300V to 400V.

[0015] The heat transfer unit 15 transfers the heat energy generated in the heat exchange object to the temperature increase object. The heat transfer unit 15 is configured to use the rotating motor 11, the inverter 12, the battery 13 and the power conversion device 14 as the heat exchange object, and can absorb the heat generated in the heat exchange object. The heat transfer unit 15 transfers the absorbed heat to the temperature increase object and increases the temperature of the temperature increase object. In the present embodiment, the temperature increase object is the battery 13. As the heat transfer unit 15, for example, it may also include a circulation path for circulating cooling water between the heat exchange object and the temperature increase object, and the temperature of the temperature increase object is increased through the cooling water. In addition, as the heat transfer unit 15, in addition to this, for example, gas (air) may also be used as a cooling fluid. In addition, as the heat transfer unit 15, for example, it may also be a component such as a radiator that abuts against the heat exchange object and the temperature increase object without using a cooling fluid.

[0016] Figure 2 1 shows the structure of the power conversion device 14. In the power conversion device 14, a high-voltage side first terminal TH1 and a high-voltage side second terminal TH2 are provided as high-voltage side terminals, and a low-voltage side first terminal TL1 and a low-voltage side second terminal TL2 are provided as low-voltage side terminals. In this embodiment, the low-voltage side terminals TL1 and TL2 are connected to the off-board charger 16, and the high-voltage side terminals TH1 and TH2 are connected to the battery 13.

[0017] The power conversion device 14 transforms the voltage input from any one of the low-voltage side terminals TL1, TL2 and the high-voltage side terminals TH1, TH2, and outputs it to the other. In the present embodiment, the power conversion device 14 has a function as a boost converter with a boost ratio of 2, and has a function of boosting the charging voltage input from the off-board charger 16 to 2 times and outputting it to the battery 13. Thus, the battery 13 is charged.

[0018] The power conversion device 14 includes a high-voltage side capacitor 20 and a low-voltage side capacitor 21. A first end of the high-voltage side capacitor 20 is connected to a high-voltage side first terminal TH1, and a second end of the high-voltage side capacitor 20 is connected to a high-voltage side second terminal TH2. A first end of the low-voltage side capacitor 21 is connected to a low-voltage side first terminal TL1, and a second end of the low-voltage side capacitor 21 is connected to a low-voltage side second terminal TL2.

[0019] The power conversion device 14 includes a high-voltage side voltage sensor 22, a low-voltage side voltage sensor 23, and a control device 24. The high-voltage side voltage sensor 22 detects a voltage VH between the high-voltage side terminals TH1 and TH2, and the low-voltage side voltage sensor 23 detects a voltage VL between the low-voltage side terminals TL1 and TL2. The detection values ​​of the voltage sensors 22 and 23 are input to the control device 24.

[0020] The power conversion device 14 includes a plurality of power conversion units. In the present embodiment, the power conversion device 14 includes a first power conversion unit 30 and a second power conversion unit 40 .

[0021] The first power conversion unit 30 includes a first upper arm 31, a first lower arm 32, and a first resonant unit 33. The first upper arm 31 and the first lower arm 32 are a series connection body of a voltage-controlled semiconductor switch. The first resonant unit 33 is a series connection body of a first inductor 34 and a first capacitor 35. In this embodiment, as the semiconductor switches of the first upper arm 31 and the first lower arm 32, an N-channel MOSFET having a body diode is used.

[0022] The drain of the upper switch QH1 of the first upper arm 31 is connected to the high-voltage first terminal TH1, and the source of the upper switch QH1 of the first upper arm 31 is connected to the drain of the lower switch QH2 of the first upper arm 31. The source of the lower switch QH2 of the first upper arm 31 is connected to the low-voltage first terminal TL1 and the drain of the upper switch QL1 of the first lower arm 32. The drain of the lower switch QL2 of the first lower arm 32 is connected to the source of the upper switch QL1 of the first lower arm 32, and the source of the lower switch QL2 of the first lower arm 32 is connected to the high-voltage second terminal TH2 and the low-voltage second terminal TL2. The first end of the first reactor 34 is connected to the connection point of the source of the upper switch QH1 of the first upper arm 31 and the drain of the lower switch QH2. The second end of the first reactor 34 is connected to the first end of the first capacitor 35. The second end of the first capacitor 35 is connected to a connection point between the source of the upper switch QL1 and the drain of the lower switch QL2 of the first lower arm 32 .

[0023] The second power conversion unit 40 includes a second upper arm 41, a second lower arm 42, and a second resonant unit 43. The second upper arm 41 and the second lower arm 42 are a series connection body of a voltage-controlled semiconductor switch. The second resonant unit 43 is a series connection body of a second inductor 44 and a second capacitor 45. In this embodiment, as the semiconductor switch of the second upper arm 41 and the second lower arm 42, an N-channel MOSFET having a body diode is used.

[0024] The drain of the upper switch SH1 of the second upper arm 41 is connected to the high-voltage first terminal TH1, and the source of the upper switch SH1 of the second upper arm 41 is connected to the drain of the lower switch SH2 of the second upper arm 41. The source of the lower switch SH2 of the second upper arm 41 is connected to the low-voltage first terminal TL1 and the drain of the upper switch SL1 of the second lower arm 42. The drain of the lower switch SL2 of the second lower arm 42 is connected to the source of the upper switch SL1 of the second lower arm 42, and the source of the lower switch SL2 of the second lower arm 42 is connected to the high-voltage second terminal TH2 and the low-voltage second terminal TL2. The first end of the second reactor 44 is connected to the connection point of the source of the upper switch SH1 of the second upper arm 41 and the drain of the lower switch SH2. The second end of the second reactor 44 is connected to the first end of the second capacitor 45. The second end of the second capacitor 45 is connected to a connection point between the source of the upper switch SL1 and the drain of the lower switch SL2 of the second lower arm 42 .

[0025] In addition, in the present embodiment, the upper switches QH1 and SH1 of the upper arms 31 and 41 correspond to the “upper arm first switch”, and the lower switches QH2 and SH2 of the upper arms 31 and 41 correspond to the “upper arm second switch”. In addition, the upper switches QL1 and SL1 of the lower arms 32 and 42 correspond to the “lower arm first switch”, and the lower switches QL2 and SL2 of the lower arms 32 and 42 correspond to the “lower arm second switch”.

[0026] The control device 24 is mainly composed of a microcomputer. The functions provided by the controller 24 can be provided by, for example, software recorded in a physical memory device and a computer executing the software, hardware, or a combination thereof.

[0027] The control device 24 turns on and off the switches QH1, QH2, QL1, and QL2 of the first power conversion unit 30, thereby setting the first power conversion unit 30 to any of the states of Mode 1 to Mode 4. Here, in the state of Mode 1, the upper switch QH1 of the first upper arm 31 and the upper switch QL1 of the first lower arm 32 are turned on, and the lower switch QH2 of the first upper arm 31 and the lower switch QL2 of the first lower arm 32 are turned off. In the state of Mode 2, the upper switch QH1 of the first upper arm 31 and the lower switch QL2 of the first lower arm 32 are turned on, and the lower switch QH2 of the first upper arm 31 and the upper switch QL1 of the first lower arm 32 are turned off.

[0028] In the state of mode 3, the lower switch QH2 of the first upper arm 31 and the lower switch QL2 of the first lower arm 32 are turned on, and the upper switch QH1 of the first upper arm 31 and the upper switch QL1 of the first lower arm 32 are turned off. In the state of mode 4, the lower switch QH2 of the first upper arm 31 and the upper switch QL1 of the first lower arm 32 are turned on, and the upper switch QH1 of the first upper arm 31 and the lower switch QL2 of the first lower arm 32 are turned off.

[0029] The control device 24 turns on and off the switches SH1 , SH2 , SL1 , and SL2 of the second power conversion unit 40 similarly to the first power conversion unit 30 , thereby setting the second power conversion unit 40 to any of the modes 1 to 4 .

[0030] The control device 24 causes each power conversion unit 30, 40 to operate as either a boost operation unit or a buck operation unit by causing each power conversion unit 30, 40 to repeatedly perform a cycle of processing consisting of mode 1 to mode 4. The boost operation is an operation of boosting the voltage input from the low-voltage side terminals TL1, TL2 and outputting the boosted voltage to the high-voltage side terminals TH1, TH2. The buck operation is an operation of stepping down the voltage input from the high-voltage side terminals TH1, TH2 and outputting the stepped-down voltage to the low-voltage side terminals TL1, TL2. The control device 24 performs temperature increase control to increase the temperature of the battery 13, which is the temperature increase object, by implementing the boost operation and the buck operation. In addition, the temperature increase control will be described later.

[0031] First, use Figure 3 and Figure 4 , the processing when the first power conversion unit 30 performs a voltage boost operation is described. Figure 3 In (a), the solid line indicates the on / off of the upper switch QH1 of the first upper arm 31, and the dotted line indicates the on / off of the lower switch QH2 of the first upper arm 31. Figure 3 In (b), the solid line indicates the turning on and off of the upper switch QL1 of the first lower arm 32 , and the dotted line indicates the turning on and off of the lower switch QL2 of the first lower arm 32 . Figure 3 (c) shows the transition of the current iQ flowing through the first resonating portion 33. Here, the sign of the current iQ flowing through the first resonating portion 33 is defined as positive when the current flows from the first end of the first reactor 34 to the second end of the first reactor 34.

[0032] When operating the first power conversion unit 30 as a boost operation unit, the control device 24 sequentially repeats the processing consisting of Mode 1, Mode 2, Mode 3, and Mode 4. The switching cycle Tsw is the total period of the periods in Mode 1 to Mode 4. Figure 4 (a) to (d) of FIG. 1 show the current path flowing through the power conversion device 14 during the boost operation for each period set to Mode 1 to Mode 4. Figure 4 In the figure, the second power conversion unit 40 and the like are omitted.

[0033] During the period when the first power conversion unit 30 is in mode 1, current flows in a closed loop including the low-voltage side first terminal TL1, the upper switch QL1 of the first lower arm 32, the first capacitor 35, the first inductor 34, the upper switch QH1 of the first upper arm 31, the high-voltage side capacitor 20, and the low-voltage side second terminal TL2. In this case, the current flows in the direction in which the sign of the current iQ flowing through the first resonance unit 33 is negative. Thus, while the first capacitor 35 is discharged, power is supplied from the low-voltage side terminals TL1 and TL2 to the high-voltage side terminals TH1 and TH2. In addition, the direction of the current during the period set to mode 1 is the direction in which the sign of the current iQ flowing through the first resonance unit 33 is negative because, as described later, the sign of the current iQ flowing through the first resonance unit 33 during the period set to mode 4 is negative.

[0034] During the period when the first power conversion unit 30 is in mode 2, current flows in a closed loop including the high-voltage side capacitor 20, the upper switch QH1 of the first upper arm 31, the first inductor 34, the first capacitor 35, and the lower switch QL2 of the first lower arm 32. During the period when the first power conversion unit 30 is in mode 2, the direction of the current is reversed from the direction of the current flowing in the period set to mode 1. That is, the sign of the current iQ flowing through the first resonance unit 33 is switched from negative to positive.

[0035] During the period when the first power conversion unit 30 is in mode 3, current flows in a closed loop including the low-voltage side first terminal TL1, the lower switch QH2 of the first upper arm 31, the first inductor 34, the first capacitor 35, the lower switch QL2 of the first lower arm 32, and the low-voltage side second terminal TL2. In this case, the current flows in the same direction as the current flowing in the period set to mode 2 just before, and the sign of the current iQ flowing through the first resonance unit 33 is positive. As a result, the first capacitor 35 is charged.

[0036] During the period when the first power conversion unit 30 is in mode 4, current flows in a closed loop including the lower switch QH2 of the first upper arm 31, the upper switch QL1 of the first lower arm 32, the first capacitor 35, and the first reactor 34. During the period when the first power conversion unit 30 is in mode 4, the direction of the current is reversed from the direction of the current flowing in the period immediately before being set to mode 3. That is, the sign of the current iQ flowing through the first resonance unit 33 is switched from positive to negative.

[0037] By performing the above-mentioned boosting operation in the first power conversion unit 30, the voltage input from the low-voltage side terminals TL1 and TL2 is boosted, and the boosted voltage is output to the high-voltage side terminals TH1 and TH2. In the boosting operation, the longer the length of the period set to Mode 2 and Mode 4 is, the larger the amplitude of the current iQ flowing through the first resonance unit 33 is. In this case, the magnitude of the power supplied from the low-voltage side terminals TL1 and TL2 to the high-voltage side terminals TH1 and TH2 increases.

[0038] Next, use Figure 5 and Figure 6 , the processing when the first power conversion unit 30 is made to perform a voltage step-down operation is described. Figure 5 In (a) to (c), the Figure 3 (a) to (c) correspond to.

[0039] When operating the first power conversion unit 30 as a step-down operation unit, the control device 24 sequentially repeats the processing consisting of Mode 1, Mode 4, Mode 3, and Mode 2. The switching cycle Tsw is the total period of the periods in Mode 1 to Mode 4. Figure 6 (a) to (d) of FIG. 1 show the current path flowing through the power conversion device 14 during the step-down operation for each period set to Mode 1 to Mode 4. Figure 6 In the figure, the second power conversion unit 40 and the like are omitted.

[0040] During the period when the first power conversion unit 30 is in mode 1, current flows in a closed loop including the high-voltage side first terminal TH1, the upper switch QH1 of the first upper arm 31, the first inductor 34, the first capacitor 35, the upper switch QL1 of the first lower arm 32, the low-voltage side capacitor 21, and the high-voltage side second terminal TH2. In this case, the current flows in the direction in which the sign of the current iQ flowing through the first resonance unit 33 is positive. Thus, while charging the first capacitor 35, power is supplied from the high-voltage side terminals TH1 and TH2 to the low-voltage side terminals TL1 and TL2. In addition, the direction of the current during the period set to mode 1 is the direction in which the sign of the current iQ flowing through the first resonance unit 33 is positive because, as described later, the sign of the current iQ flowing through the first resonance unit 33 during the period set to mode 2 is positive.

[0041] During the period when the first power conversion unit 30 is in mode 4, current flows in a closed loop including the lower switch QH2 of the first upper arm 31, the upper switch QL1 of the first lower arm 32, the first capacitor 35, and the first reactor 34. During the period when the first power conversion unit 30 is in mode 4, the direction of the current is reversed from the direction of the current flowing in the period immediately before being set to mode 1. That is, the sign of the current iQ flowing through the first resonance unit 33 is switched from positive to negative.

[0042] During the period when the first power conversion unit 30 is in mode 3, current flows in a closed loop including the low-voltage side second terminal TL2, the lower switch QL2 of the first lower arm 32, the first capacitor 35, the first reactor 34, the lower switch QH2 of the first upper arm 31, and the low-voltage side first terminal TL1. In this case, the current flows in the same direction as the current flowing during the period set to mode 4 just before, and the sign of the current iQ flowing through the first resonance unit 33 is negative. As a result, the first capacitor 35 is discharged.

[0043] During the period when the first power conversion unit 30 is in mode 2, current flows in a closed loop including the high-voltage side capacitor 20, the upper switch QH1 of the first upper arm 31, the first inductor 34, the first capacitor 35, and the lower switch QL2 of the first lower arm 32. During the period when the first power conversion unit 30 is in mode 2, the direction of the current is reversed from the direction of the current flowing during the period set to mode 3. That is, the sign of the current iQ flowing through the first resonance unit 33 is switched from negative to positive.

[0044] By performing the above-mentioned step-down operation in the first power conversion unit 30, the voltage input from the high-voltage side terminals TH1 and TH2 is stepped down, and the stepped-down voltage is output to the low-voltage side terminals TL1 and TL2. In the step-down operation, the longer the length of the period of mode 2 and mode 4 is, the larger the amplitude of the current iQ flowing through the first resonance unit 33 is. In this case, the magnitude of the power supplied from the high-voltage side terminals TH1 and TH2 to the low-voltage side terminals TL1 and TL2 increases.

[0045] Next, the temperature increase control is described. Unlike the present embodiment, as a temperature increase control for increasing the temperature of the battery 13 as the temperature increase target, it is conceivable to alternately perform a voltage increase operation and a voltage reduction operation. Thus, power is transmitted between the low-voltage side terminals TL1 and TL2 and the high-voltage side terminals TH1 and TH2. In this case, a part of the transmitted power is converted into heat energy, and the converted heat energy is transmitted to the battery 13 via the heat transfer unit 15. Thus, the heat energy is used to increase the temperature of the battery 13.

[0046] In order to increase the thermal energy used in the temperature rise of the battery 13, it is considered to increase the power transmitted in the temperature rise control. However, the power that is not converted into thermal energy in the transmitted power is supplied to the low-voltage side terminals TL1, TL2 or the high-voltage side terminals TH1, TH2. In detail, during the period of the boost action, power is supplied to the high-voltage side terminals TH1, TH2. As a result, the terminal voltage VH of the high-voltage side terminals TH1, TH2 rises. In addition, during the period of the step-down action, power is supplied to the low-voltage side terminals TL1, TL2. As a result, the terminal voltage VL of the low-voltage side terminals TL1, TL2 rises. In this case, the terminal voltage VL of the low-voltage side terminals TL1, TL2 may reach the upper limit voltage determined by the withstand voltage of the low-voltage side capacitor 21, etc., or the terminal voltage VH of the high-voltage side terminals TH1, TH2 may reach the upper limit voltage determined by the withstand voltage of the high-voltage side capacitor 20, etc. As a result, increasing the power transmitted in the temperature rise control may be limited. As a result, the thermal energy used to increase the temperature of the battery 13 may not be increased sufficiently, and the efficiency of the temperature increase control may be reduced.

[0047] Therefore, in the present embodiment, the control device 24 performs control to make one of the first power conversion unit 30 and the second power conversion unit 40 perform a voltage-raising operation and the other perform a voltage-lowering operation as the temperature-raising control. Figure 7 The temperature increase control when the voltage step-up operation is performed in the first power conversion unit 30 and the voltage step-down operation is performed in the second power conversion unit 40 will be described.

[0048] Figure 7 (a), (b) and the previous Figure 3 (a) and (b) correspond to each other. Figure 7 In (c), the solid line indicates the on / off of the upper switch SH1 of the second upper arm 41, and the dotted line indicates the on / off of the lower switch SH2 of the second upper arm 41. Figure 7 In (d), the solid line indicates the on / off of the upper switch SL1 of the second lower arm 42, and the dotted line indicates the on / off of the lower switch SL2 of the second lower arm 42. Figure 7 In (e), the solid line indicates the change of the current iQ flowing through the first resonance part 33, and the dotted line indicates the change of the current iS flowing through the second resonance part 43. Figure 7 In (f) of FIG. 1 , the solid line indicates the change in the electric power PL supplied to the low-voltage terminals TL1 , TL2 , and the dotted line indicates the change in the output electric power PH of the battery 13 .

[0049] The control device 24 operates the first power conversion unit 30 as a voltage step-up unit in the temperature rise control. That is, in the first power conversion unit 30, the processing consisting of mode 1, mode 2, mode 3, and mode 4 is repeated in sequence. In this case, power is supplied from the low-voltage side terminals TL1 and TL2 to the high-voltage side terminals TH1 and TH2. On the other hand, the control device 24 operates the second power conversion unit 40 as a voltage step-down unit in the temperature rise control. That is, in the second power conversion unit 40, the processing consisting of mode 1, mode 4, mode 3, and mode 2 is repeated in sequence. In this case, power is supplied from the high-voltage side terminals TH1 and TH2 to the low-voltage side terminals TL1 and TL2.

[0050] The control device 24 operates the first power conversion unit 30 as a boost operation unit and the second power conversion unit 40 as a step-down operation unit in the temperature rise control. In this case, power is supplied to the low-voltage side terminals TL1 and TL2 by step-down operation and power is output from the low-voltage side terminals TL1 and TL2 by step-up operation simultaneously. In addition, power is supplied to the high-voltage side terminals TH1 and TH2 by step-down operation and power is output from the high-voltage side terminals TH1 and TH2 by step-down operation simultaneously. Thus, in the implementation of the temperature rise control, the changes in the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 and the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 can be suppressed.

[0051] During the implementation of the temperature increase control, a current circulates between the first power conversion unit 30 and the second power conversion unit 40. A current represented by the change in the current iQ flowing through the first resonance unit 33 flows through the first power conversion unit 30. As a result, a switching loss caused by the on / off of each switch QH1, QH2, QL1, and QL2 and a conduction loss caused by the current flowing through each switch QH1, QH2, QL1, and QL2 are generated in the first power conversion unit 30. In addition, a current represented by the change in the current iS flowing through the second resonance unit 43 flows through the second power conversion unit 40. As a result, a switching loss caused by the on / off of each switch SH1, SH2, SL1, and SL2 and a conduction loss caused by the current flowing through each switch SH1, SH2, SL1, and SL2 are generated in the second power conversion unit 40. The switching loss and conduction loss generated in each of the switches QH1, QH2, QL1, QL2, SH1, SH2, SL1, and SL2 are converted into heat energy, and the heat energy is transferred to the battery 13 via the heat transfer unit 15. As a result, the temperature of the battery 13 rises.

[0052] In this embodiment, if Figure 7As shown in (f), the power PL supplied to the low-voltage side terminals TL1 and TL2 is maintained at approximately 0W. Therefore, the change in the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 during the temperature rise control can be suppressed. In addition, similarly to the case of the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2, the change in the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 can also be suppressed. The output power PH of the battery 13 is greater than 0W because the amount of power converted into heat energy by the temperature rise control is output from the battery 13.

[0053] When the power conversion units 30 and 40 are operated as either the boost operation unit or the buck operation unit, the control device 24 sets the switching frequency fsw of each power conversion unit 30 and 40. Here, the switching frequency fsw is the reciprocal of the switching period Tsw. In the present embodiment, the control device 24 sets the value of the switching frequency fsw to different values ​​when the temperature rise control is performed and when the power conversion units 30 and 40 are operated only as either the boost operation or the buck operation.

[0054] use Figure 8 , a method for setting the switching frequency fsw of each power conversion unit 30, 40 is described. Figure 8 The relationship between the switching frequency fsw and the impedance ZLC of each resonant part 33, 43 is shown. The impedance ZLC of each resonant part 33, 43 is the minimum value when the switching frequency fsw is consistent with the resonant frequency fr. In addition, the resonant frequency fr of the first resonant part 33 is determined by the inductance of the first inductor 34 and the electrostatic capacitance of the first capacitor 35, and the resonant frequency fr of the second resonant part 43 is determined by the inductance of the second inductor 44 and the electrostatic capacitance of the second capacitor 45.

[0055] In the capacitive region where the switching frequency fsw is lower than the resonance frequency fr, the higher the switching frequency fsw, the lower the impedance ZLC of each resonance part 33, 43. In the inductive region where the switching frequency fsw is higher than the resonance frequency fr, the higher the switching frequency fsw, the higher the impedance ZLC of each resonance part 33, 43.

[0056] In order to operate the power conversion device 14 as a step-up / step-down converter, it is considered that each power conversion unit 30, 40 performs only one of the step-up operation and the step-down operation. In this case, in order to improve the ratio of the output power to the input power, it is desirable that the switching frequency fsw is a frequency near the resonance frequency fr at which the impedance ZLC of each resonance unit 33, 43 is the minimum. Therefore, in the present embodiment, the control device 24 sets the switching frequency fsw of the first power conversion unit 30 to the resonance frequency fr of the first resonance unit 33 and the switching frequency fsw of the second power conversion unit 40 to the resonance frequency fr of the second resonance unit 43 when each power conversion unit 30, 40 operates only as one of the step-up operation and the step-down operation. In addition, the switching frequency fsw of the first power conversion unit 30 and the second power conversion unit 40 is not limited to being set to the resonance frequency fr of the first resonance unit 33 and the second resonance unit 43, and can also be set to a frequency near the resonance frequency fr within a range where the reduction in the ratio of the output power to the input power is not a problem.

[0057] On the other hand, in the case of temperature rise control, in order to improve the efficiency of converting the input power into heat energy, it is desirable to set the switching frequency fsw so that the impedance ZLC of each resonance unit 33, 43 is greater than the minimum value. Therefore, the control device 24 sets the switching frequency fsw of the first power conversion unit 30 and the second power conversion unit 40 to a value different from the resonance frequency fr of the first resonance unit 33 and the second resonance unit 43 when performing temperature rise control.

[0058] Here, during the period when each power conversion unit 30, 40 is in either mode 2 or mode 4, by controlling the current IQ, IS flowing through each resonance unit 33, 43, either step-up operation or step-down operation is performed in each power conversion unit 30, 40. The control of the current IQ, IS flowing through each resonance unit 33, 43 is performed by utilizing the inductance component of each resonance unit 33, 43. Therefore, it is considered to improve the controllability of the current IQ, IS flowing through each resonance unit 33, 43 by setting the switching frequency fsw of each power conversion unit 30, 40 to a value in the inductance region.

[0059] Therefore, when performing temperature increase control, the control device 24 sets the switching frequency fsw of the first power conversion unit 30 to be higher than the resonance frequency fr of the first resonance unit 33, and sets the switching frequency fsw of the second power conversion unit 40 to be higher than the resonance frequency fr of the second resonance unit 43. For example, the control device 24 sets the switching frequency fsw of the first power conversion unit 30 and the second power conversion unit 40 to a value twice the resonance frequency fr of the first resonance unit 33 and the second resonance unit 43. In this case, the switching frequency fsw of the first power conversion unit 30 and the second power conversion unit 40 is higher than the switching frequency fsw when each power conversion unit 30 and 40 operates only in either the step-up operation or the step-down operation. In addition, the switching frequency fsw of the first power conversion unit 30 and the second power conversion unit 40 is not limited to being set to a value twice the resonance frequency fr of the first resonance unit 33 and the second resonance unit 43, and may be set to a value such as 1.5 times, 3 times, or 4 times the resonance frequency fr of the first resonance unit 33 and the second resonance unit 43.

[0060] In the implementation of temperature rise control, the power supplied to at least one of the low-voltage side terminals TL1, TL2 and the high-voltage side terminals TH1, TH2 may have an error. In this case, the power supplied from either the low-voltage side terminals TL1, TL2 and the high-voltage side terminals TH1, TH2 to the other may become excessive and cause an overvoltage abnormal state. In addition, the power supplied from either the low-voltage side terminals TL1, TL2 and the high-voltage side terminals TH1, TH2 to the other may become insufficient and cause a low-voltage abnormal state. Therefore, it is desired to control the inter-terminal voltage VL of the low-voltage side terminals TL1, TL2 and the inter-terminal voltage VH of the high-voltage side terminals TH1, TH2 while performing temperature rise control.

[0061] Here, the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 changes according to the power supplied to the low-voltage side terminals TL1 and TL2 and the power output from the low-voltage side terminals TL1 and TL2. In addition, the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 changes according to the power supplied to the high-voltage side terminals TH1 and TH2 and the power output from the high-voltage side terminals TH1 and TH2. In view of this, it is considered that the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 and the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 can be controlled by adjusting the power transmitted by the step-up action and the step-down action.

[0062] Therefore, in the temperature rise control, the control device 24 sets at least one of the lengths of the periods set to mode 2 and mode 4 in the step-up operation and the step-down operation based on at least one of the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 and the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2. In the present embodiment, the control device 24 acquires the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 and the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2. The control device 24 may acquire the detection value of the low-voltage side voltage sensor 23 as the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2, and may acquire the detection value of the high-voltage side voltage sensor 22 as the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2. In the temperature rise control, the control device 24 sets the lengths of the periods set to mode 2 and mode 4 in the step-up operation and the step-down operation based on the acquired inter-terminal voltages VH and VL. In addition, the control device 24 corresponds to the "acquisition unit".

[0063] Specifically, if Fig. 9 As shown, when the control device 24 determines that the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 is greater than the first threshold Va, the length of the period set to mode 2 and mode 4 is extended in the power conversion unit on the side of each power conversion unit 30 and 40 that performs the boost operation. As a result, the power output from the low-voltage side terminals TL1 and TL2 by the boost operation increases. In addition, when the control device 24 determines that the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 is greater than the first threshold Va, the length of the period set to mode 2 and mode 4 is shortened in the power conversion unit on the side of each power conversion unit 30 and 40 that performs the step-down operation. As a result, the power supplied to the low-voltage side terminals TL1 and TL2 by the step-down operation is reduced. In this case, the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 is reduced.

[0064] When the control device 24 determines that the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 is a value lower than the first threshold value Va, that is, below the second threshold value Vb, the length of the period set to mode 2 and mode 4 is shortened in the power conversion unit of the power conversion unit 30 and 40 that performs the boost operation. As a result, the power output from the low-voltage side terminals TL1 and TL2 by the boost operation is reduced. In addition, when the control device 24 determines that the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 is below the second threshold value Vb, the length of the period set to mode 2 and mode 4 is extended in the power conversion unit of the power conversion unit 30 and 40 that performs the step-down operation. As a result, the power supplied to the low-voltage side terminals TL1 and TL2 by the step-down operation increases. In this case, the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 becomes higher.

[0065] When the control device 24 determines that the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 is greater than the third threshold value Vc, the control device 24 shortens the length of the period set to mode 2 and mode 4 in the power conversion unit that performs the boosting operation among the power conversion units 30 and 40. As a result, the power supplied to the high-voltage side terminals TH1 and TH2 by the boosting operation is reduced. In addition, when the control device 24 determines that the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 is greater than the third threshold value Vc, the control device 24 extends the length of the period set to mode 2 and mode 4 in the power conversion unit that performs the step-down operation among the power conversion units 30 and 40. As a result, the power output from the high-voltage side terminals TH1 and TH2 by the step-down operation increases. In this case, the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 is reduced.

[0066] When the control device 24 determines that the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 is a value lower than the third threshold value Vc, that is, below the fourth threshold value Vd, the control device 24 extends the length of the period set to mode 2 and mode 4 in the power conversion unit on the side of the power conversion units 30 and 40 that performs the boost operation. As a result, the power supplied to the high-voltage side terminals TH1 and TH2 by the boost operation increases. In addition, when the control device 24 determines that the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 is below the fourth threshold value Vd, the control device 24 shortens the length of the period set to mode 2 and mode 4 in the power conversion unit on the side of the power conversion units 30 and 40 that performs the step-down operation. As a result, the power output from the high-voltage side terminals TH1 and TH2 by the step-down operation decreases. In this case, the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 becomes higher.

[0067] The control device 24 preferably repeatedly performs the process of setting the length of the period set to Mode 2 or Mode 4 in the above-mentioned step-up operation and step-down operation in a predetermined control cycle. In each control cycle, the amount of change when the length of the period set to Mode 2 or Mode 4 is extended or shortened may be set to a fixed value or may be variably set based on the values ​​of the inter-terminal voltages VH and VL.

[0068] In addition, the control device 24 preferably maintains the length of the period set to mode 2 or mode 4 as it is when it is determined that the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 is within the first range and the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 is within the second range. Here, the first range is a voltage range defined by the first threshold Va and the second threshold Vb, and the second range is a voltage range defined by the third threshold Vc and the fourth threshold Vd. In addition, the control device 24 may also set the initial setting value instead of maintaining the length of the period set to mode 2 or mode 4 as it is when it is determined that the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 is within the first range and the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 is within the second range. The initial setting value is the length of the period set to mode 2 or mode 4 set before it is determined that the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 is outside the first range or the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 is outside the second range.

[0069] In addition, the first threshold Va and the second threshold Vb are preferably set based on the withstand voltage of the low-voltage terminals TL1 and TL2. The third threshold Vc and the fourth threshold Vd are preferably set based on the withstand voltage of the high-voltage terminals TH1 and TH2.

[0070] According to the present embodiment described in detail above, the following effects can be obtained.

[0071] As the temperature rise control, the first power conversion unit 30 performs a voltage step-up operation, and the second power conversion unit 40 performs a voltage step-down operation. In this case, in the high-voltage side terminals TH1 and TH2, power is supplied from the low-voltage side terminals TL1 and TL2 by a voltage step-up operation, and on the other hand, power is output to the low-voltage side terminals TL1 and TL2 by a voltage step-down operation. In addition, in the low-voltage side terminals TL1 and TL2, power is supplied from the high-voltage side terminals TH1 and TH2 by a voltage step-down operation, and on the other hand, power is output to the high-voltage side terminals TH1 and TH2 by a voltage step-up operation. Thus, in the implementation of the temperature rise control, power can be transmitted between the first power conversion unit 30 and the second power conversion unit 40 while suppressing changes in the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 and the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2. Therefore, in the implementation of the temperature rise control, the power transmitted in the temperature rise control can be increased while suppressing the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 and the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 from reaching the upper limit voltage. As a result, the thermal energy used in the temperature rise of the battery 13 can be fully increased, and the efficiency of the temperature rise control can be improved.

[0072] The high-voltage side terminals TH1 and TH2 are connected to the battery 13, and the low-voltage side terminals TL1 and TL2 are connected to the off-board charger 16. In this case, since the temperature of the battery 13 is low, it is considered that the power that can be input and output from the battery 13 is reduced. Therefore, when the temperature of the battery 13 is low, the increase in the power transmitted during the temperature increase control may be limited, resulting in a decrease in the efficiency of the temperature increase control.

[0073] In view of this, in the present embodiment in which the voltage-boosting operation and the voltage-reducing operation are performed simultaneously as the temperature-raising control, the power output from the battery 13 is the amount of power converted into heat energy by the temperature-raising control. Thus, compared with the control of the comparative example in which the voltage-boosting operation and the voltage-reducing operation are performed alternately as the temperature-raising control, the increase in the power output from the battery 13 can be suppressed. Therefore, even in a situation in which the power that can be input and output from the battery 13 becomes low due to the low temperature of the battery 13, the occurrence of a situation in which the increase in the power transmitted in the temperature-raising control is limited can be suppressed. As a result, the efficiency of the temperature-raising control can be improved.

[0074] The power conversion device 14 has a function of charging the battery 13 by boosting the voltage input from the off-board charger 16 and outputting it to the battery 13. In this case, since the temperature around the power conversion device 14 is low, the power that can be input and output to the battery 13 may decrease, resulting in a longer charging time for the battery 13. In view of this, by performing the temperature increase control of this embodiment, the temperature of the battery 13 can be quickly increased. As a result, the battery 13 is charged after the power that can be input and output to the battery 13 is increased. As a result, it is possible to suppress the charging time of the battery 13 from being prolonged.

[0075] Specifically, Fig.10 An example of comparing the charging time of the battery 13 between the comparative example and the present embodiment when the air temperature around the power conversion device 14 is -10 degrees is shown. In the comparative example, the temperature increase control of the present embodiment is not performed, and the battery 13 is charged while the temperature of the battery 13 is relatively low. On the other hand, in the present embodiment, the battery 13 is charged after the temperature of the battery 13 is increased by the temperature increase control. In this case, since the battery 13 is charged after the electric power that can be input and output to the battery 13 is increased, the charging time of the battery 13 can be reduced by 35% compared with the comparative example.

[0076] The power conversion device 14 has both the function of charging the battery 13 and the function of raising the temperature of the battery 13. Therefore, the power conversion device 14 used for charging the battery 13 can perform temperature increase control to raise the temperature of the battery 13.

[0077] The voltage step-up and voltage step-down operations are performed by turning on and off the switches QH1, QH2, QL1, QL2 of the first power conversion unit 30 and the switches SH1, SH2, SL1, SL2 of the second power conversion unit 40. In this case, current circulates between the first power conversion unit 30 and the second power conversion unit 40. Thus, the switching loss and conduction loss generated in the switches QH1, QH2, QL1, QL2, SH1, SH2, SL1, SL2 are converted into heat energy.

[0078] Specifically, in Fig.11 In FIG. 1 , the heat energy generated by temperature rise control is shown for each switch QH1, QH2, QL1, QL2, SH1, SH2, SL1, and SL2. Fig.11 , the thermal energy is expressed as a ratio to a target value. The target value is the thermal energy required to increase the temperature of the battery 13 and is a value set based on thermal characteristics such as the allowable power loss and operating temperature range of each switch QH1, QH2, QL1, QL2, SH1, SH2, SL1, and SL2.

[0079] By performing temperature rise control, the same degree of heat energy and heat energy close to the target value are generated in each switch QH1, QH2, QL1, QL2, SH1, SH2, SL1, and SL2. The heat energy generated in each switch QH1, QH2, QL1, QL2, SH1, SH2, SL1, and SL2 is transferred to the battery 13 via the heat transfer unit 15. As a result, the temperature of the battery 13 can be increased. In addition, Fig.11 This is an example of operation, and the heat energy generated in each switch QH1, QH2, QL1, QL2, SH1, SH2, SL1, and SL2 may change in various ways depending on the operation conditions.

[0080] Different switching frequencies fsw are set when only one of the step-up operation and the step-down operation is performed in each power conversion unit 30 and 40 and when temperature increase control is performed. Specifically, when only one of the step-up operation and the step-down operation is performed in each power conversion unit 30 and 40, the switching frequency fsw of the first power conversion unit 30 and the second power conversion unit 40 is set to the resonance frequency fr of the first resonance unit 33 and the second resonance unit 43. Thus, compared with the case where the switching frequency fsw is set to a frequency other than the resonance frequency fr, the ratio of the output power to the input power is improved. On the other hand, when temperature increase control is performed, the switching frequency fsw of the first power conversion unit 30 and the second power conversion unit 40 is set to a value deviated from the resonance frequency fr of the first resonance unit 33 and the second resonance unit 43. Thus, compared with the case where the switching frequency fsw is set to the resonance frequency fr, the switching loss caused by the on and off of each switch QH1, QH2, QL1, QL2, SH1, SH2, SL1, and SL2 can be increased. As a result, the efficiency of converting input electric power into thermal energy can be improved.

[0081] When temperature increase control is performed, the switching frequency fsw of the first power conversion unit 30 and the second power conversion unit 40 is higher than the resonance frequency fr of the first resonance unit 33 and the second resonance unit 43. In this case, since the switching frequency fsw of the first power conversion unit 30 and the second power conversion unit 40 is set to a value in the inductive region, the controllability of the currents IQ and IS flowing through the first resonance unit 33 and the second resonance unit 43 is improved. Thus, even when various values ​​are set as the values ​​of the inter-terminal voltages VL and VH, it is possible to reliably operate either of the power conversion units 30 and 40 as a voltage step-up operation unit and reliably operate the other as a voltage step-down operation unit. As a result, temperature increase control can be reliably performed.

[0082] In the implementation of temperature rise control, the length of the period of mode 2 and mode 4 in the step-up control and step-down control is set based on the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 and the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2. As a result, the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 and the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 can be controlled while the temperature rise control is being performed. As a result, the occurrence of an overvoltage state and a low voltage state can be suppressed in the implementation of temperature rise control.

[0083] <Second embodiment> Hereinafter, the second embodiment will be described focusing on the differences from the first embodiment.

[0084] When temperature rise control is performed, current may flow through floating capacitance between the power conversion device 14 and the ground. The ground is, for example, a body ground formed of a metal body frame of the vehicle 10 and is a wiring path on the low potential side. The current flowing through the floating capacitance is a noise current flowing into or out of the power conversion device 14, and the noise current is preferably below a limit value.

[0085] In view of this, in the present embodiment, either one of the power conversion units 30 and 40 can be operated as a voltage-boosting unit, and the other one can be operated as a voltage-dropping unit. Therefore, in the temperature increase control, the control device 24 synchronizes the voltage-boosting operation of the power conversion unit operating as the voltage-boosting unit and the voltage-dropping operation of the power conversion unit operating as the voltage-dropping unit.

[0086] Specifically, use Fig.12 Provide explanation. Fig.12 A control example is shown in which the voltage step-down operation executed in the first power conversion unit 30 and the voltage step-up operation executed in the second power conversion unit 40 are synchronized. Fig.12 (a) to (d) correspond to the previous Figure 7 (a)~(d).

[0087] The upper switch QH1 of the first upper arm 31 is turned on and off synchronously with the lower switch SL2 of the second lower arm 42, and the lower switch QH2 of the first upper arm 31 is turned on and off synchronously with the upper switch SL1 of the second lower arm 42. In addition, the upper switch QL1 of the first lower arm 32 is turned on and off synchronously with the lower switch SH2 of the second upper arm 41, and the lower switch QL2 of the first lower arm 32 is turned on and off synchronously with the upper switch SH1 of the second upper arm 41.

[0088] Here, noise current is generated at the timing when the switches QH1 , QH2 , QL1 , QL2 , SH1 , SH2 , SL1 , and SL2 are turned on and off. Fig.13 (a) to (d) show current paths flowing through the power conversion device 14 and the ground at the first time t1 to the fourth time t4, which are times when noise current is generated.

[0089] At the first time t1, the upper switch QH1 of the first upper arm 31 and the lower switch SL2 of the second lower arm 42 are turned on, and the lower switch QH2 of the first upper arm 31 and the upper switch SL1 of the second lower arm 42 are turned off. The switches QL1 and QL2 of the first lower arm 32 and the switches SH1 and SH2 of the second upper arm 41 are not switched on and off.

[0090] In this case, the first outflow current ia1 flows through the floating capacitor 51 between the connection point of the source of the upper switch QH1 and the drain of the lower switch QH2 of the first upper arm 31 and the ground. The first outflow current ia1 is a current flowing in the direction from the power conversion device 14 toward the ground, and its magnitude is represented by the following formula (e1).

[0091] [Mathematical formula 1] Here, CH1 is the capacitance value of the floating capacitor 51 between the connection point of the source of the upper switch QH1 and the drain of the lower switch QH2 in the first upper arm portion 31 and the ground.

[0092] In addition, the first inflow current ib1 flows through the floating capacitor 52 between the connection point of the source of the upper switch SL1 and the drain of the lower switch SL2 of the second lower arm 42 and the ground. The first inflow current ib1 is a current flowing in the direction from the ground toward the power conversion device 14, and its magnitude is represented by the following formula (e2).

[0093] [Mathematical formula 2] Here, CL2 is the capacitance value of the floating capacitor 52 between the connection point of the source of the upper switch SL1 and the drain of the lower switch SL2 in the second lower arm 42 and the ground. The first outflow current ia1 and the first inflow current ib1 are currents that flow in opposite directions to each other and circulate between the first power conversion unit 30 and the second power conversion unit 40 via the ground. In this case, since the current flowing out from the power conversion device 14 to the ground and the current flowing into the power conversion device 14 from the ground cancel each other, the difference between the magnitude of the first outflow current ia1 and the magnitude of the first inflow current ib1 becomes a noise current.

[0094] Here, according to the above formulas (e1) and (e2), the magnitude of each current ia1, ib1 is the product of the capacitance value CH1, CL2 of each floating capacitor 51, 52 and the change in voltage applied to each floating capacitor 51, 52. Therefore, assuming that the capacitance values ​​CH1, CL2 of each floating capacitor 51, 52 are equal, the greater the difference between the change in voltage caused by the on / off of each switch QH1, QH2 of the first upper arm 31 and the change in voltage caused by the on / off of each switch SL1, SL2 of the second lower arm 42, the greater the magnitude of the noise current.

[0095] At the second time t2, the upper switch QL1 of the first lower arm 32 and the lower switch SH2 of the second upper arm 41 are turned on, and the lower switch QL2 of the first lower arm 32 and the upper switch SH1 of the second upper arm 41 are turned off. The switches QH1 and QH2 of the first upper arm 31 and the switches SL1 and SL2 of the second lower arm 42 are not switched on and off.

[0096] In this case, the second outflow current ia2 flows through the floating capacitor 53 between the connection point of the source of the upper switch QL1 and the drain of the lower switch QL2 of the first lower arm 32 and the ground. The second outflow current ia2 is a current flowing in the direction from the power conversion device 14 toward the ground, and its magnitude is represented by the following formula (e3).

[0097] [Mathematical formula 3] Here, CL1 is the capacitance value of the floating capacitor 53 between the connection point of the source of the upper switch QL1 and the drain of the lower switch QL2 in the first lower arm 32 and the ground.

[0098] In addition, the second inflow current ib2 flows through the floating capacitor 54 between the connection point of the source of the upper switch SH1 and the drain of the lower switch SH2 of the second upper arm 41 and the ground. The second inflow current ib2 is a current flowing in the direction from the ground to the power conversion device 14, and its magnitude is represented by the following formula (e4).

[0099] [Formula 4] Here, CH2 is the capacitance value of the floating capacitor 54 between the connection point of the source of the upper switch SH1 and the drain of the lower switch SH2 in the second upper arm 41 and the ground. The second outflow current ia2 and the second inflow current ib2 are currents that flow in opposite directions to each other and circulate between the first power conversion unit 30 and the second power conversion unit 40 via the ground. In this case, since the current flowing out from the power conversion device 14 to the ground and the current flowing into the power conversion device 14 from the ground cancel each other, the difference between the magnitude of the second outflow current ia2 and the magnitude of the second inflow current ib2 becomes a noise current.

[0100] Here, according to the above formulas (e3) and (e4), the magnitude of each current ia2, ib2 is the product of the capacitance values ​​CL1, CH2 of each floating capacitor 53, 54 and the change in voltage applied to each floating capacitor 53, 54. Therefore, assuming that the capacitance values ​​CL1, CH2 of each floating capacitor 53, 54 are equal, the greater the difference between the change in voltage caused by the on / off of each switch QL1, QL2 of the first lower arm 32 and the change in voltage caused by the on / off of each switch SH1, SH2 of the second upper arm 41, the greater the magnitude of the noise current.

[0101] At the third time t3, the lower switch QH2 of the first upper arm 31 and the upper switch SL1 of the second lower arm 42 are turned on, and the upper switch QH1 of the first upper arm 31 and the lower switch SL2 of the second lower arm 42 are turned off. The switches QL1 and QL2 of the first lower arm 32 and the switches SH1 and SH2 of the second upper arm 41 are not switched on and off.

[0102] In this case, the third inflow current ib3 flows through the floating capacitor 51 between the connection point of the source of the upper switch QH1 and the drain of the lower switch QH2 of the first upper arm 31 and the ground. The third inflow current ib3 is a current flowing in the direction from the ground toward the power conversion device 14, and its magnitude is the same as the first outflow current ia1. In other words, the magnitude of the third inflow current ib3 is represented by the right side of the above formula (e1).

[0103] In addition, the third outflow current ia3 flows through the floating capacitor 52 between the connection point of the source of the upper switch SL1 and the drain of the lower switch SL2 of the second lower arm 42 and the ground. The third outflow current ia3 is a current flowing in the direction from the power conversion device 14 toward the ground, and its magnitude is the same as the first inflow current ib1. In other words, the magnitude of the third outflow current ia3 is represented by the right side of the above formula (e2).

[0104] The third outflow current ia3 and the third inflow current ib3 are currents that flow in opposite directions to each other, and circulate between the first power conversion unit 30 and the second power conversion unit 40 via the ground. In this case, since the current flowing out from the power conversion device 14 to the ground and the current flowing into the power conversion device 14 from the ground are offset, a noise current is generated according to the difference between the magnitude of the third outflow current ia3 and the magnitude of the third inflow current ib3, as in the case of the first time t1.

[0105] At the fourth time t4, the lower switch QL2 of the first lower arm 32 and the upper switch SH1 of the second upper arm 41 are turned on, and the upper switch QL1 of the first lower arm 32 and the lower switch SH2 of the second upper arm 41 are turned off. The switches QH1 and QH2 of the first upper arm 31 and the switches SL1 and SL2 of the second lower arm 42 are not switched on and off.

[0106] In this case, the fourth inflow current ib4 flows through the floating capacitor 53 between the connection point of the source of the upper switch QL1 and the drain of the lower switch QL2 of the first lower arm 32 and the ground. The fourth inflow current ib4 is a current flowing in the direction from the ground toward the power conversion device 14, and its magnitude is the same as the second outflow current ia2. In other words, the magnitude of the fourth inflow current ib4 is represented by the right side of the above formula (e3).

[0107] In addition, the fourth outflow current ia4 flows through the floating capacitor 54 between the connection point of the source of the upper switch SH1 and the drain of the lower switch SH2 of the second upper arm 41 and the ground. The fourth outflow current ia4 is a current flowing in the direction from the power conversion device 14 toward the ground, and its magnitude is the same as the second inflow current ib2. In other words, the magnitude of the fourth outflow current ia4 is represented by the right side of the above formula (e4).

[0108] The fourth outflow current ia4 and the fourth inflow current ib4 are currents that flow in opposite directions to each other and circulate between the first power conversion unit 30 and the second power conversion unit 40 via the grounding member. In this case, since the current flowing out from the power conversion device 14 to the grounding member and the current flowing into the power conversion device 14 from the grounding member are offset, a noise current is generated according to the difference between the magnitude of the fourth outflow current ia4 and the magnitude of the fourth inflow current ib4, as in the case of the second moment t2.

[0109] As a temperature control, Fig.14 An example is shown in which a voltage step-up operation is performed in the first power conversion unit 30 and a voltage step-down operation is performed in the second power conversion unit 40 . Fig.14 (a) to (f) correspond to Figure 7 (a)~(f). Fig.14 In (e), since the voltage step-up operation performed in the first power conversion unit 30 and the voltage step-down operation performed in the second power conversion unit 40 are synchronized, the transitions of the current iQ flowing through the first resonance unit 33 and the current iS flowing through the second resonance unit 43 overlap.

[0110] In this embodiment, as in the previous Figure 7Similarly to the case described in , the temperature of the battery 13 can be raised while suppressing the change of the inter-terminal voltage VL of the low-voltage terminals TL1 and TL2 and the inter-terminal voltage VH of the high-voltage terminals TH1 and TH2 during the temperature increase control. In addition, the noise current generated during the implementation of the temperature increase control is reduced.

[0111] Specifically, Fig.15 A graph is shown comparing the magnitude of the noise current under temperature increase control in the case where the voltage VH between the high-voltage side terminals TH1 and TH2 is twice the voltage VL between the low-voltage side terminals TL1 and TL2, and the temperature increase control in the present embodiment where the voltage increase and voltage reduction actions are synchronized.

[0112] When the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 is twice the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2, the magnitude of the first outflow current ia1 becomes CH1×dVL / dt according to the above formula (e1). On the other hand, the magnitude of the first inflow current ib1 becomes CL2×dVL / dt according to the above formula (e2). In this case, if it is assumed that the capacitance values ​​CH1 and CL2 of each floating capacitor 51 and 52 are the same value, since the magnitude of the first outflow current ia1 is the same as the magnitude of the first inflow current ib1, almost no noise current is generated.

[0113] like Fig.15 As shown, in the present embodiment where the step-up operation and the step-down operation are synchronized, the magnitude of the noise current is reduced to about 1 / 1000 times compared to the case where the step-up operation and the step-down operation are not synchronized. Therefore, the generation of the noise current can be suppressed while performing the same temperature increase control as the first embodiment.

[0114] in addition, Fig.15 The effect of suppressing the generation of noise current shown may vary according to the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 and the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2. Specifically, when the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 is not twice the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2, the noise current increases when the step-up action and the step-down action are synchronized.

[0115] <Third embodiment> Hereinafter, the third embodiment will be described focusing on the differences from the second embodiment.

[0116] In this embodiment, if Fig.16 As shown, the power conversion device 14 includes a third power conversion unit 60 in addition to the first power conversion unit 30 and the second power conversion unit 40. Fig.16 In the figure, the control device 24 is omitted for convenience. Figure 2 The same structures are denoted by the same symbols.

[0117] The third power conversion unit 60 includes a third upper arm 61, a third lower arm 62, and a third resonant unit 63. The third upper arm 61 and the third lower arm 62 are a series connection body of a voltage-controlled semiconductor switch. The third resonant unit 63 is a series connection body of a third inductor 64 and a third capacitor 65. In this embodiment, as the semiconductor switches of the third upper arm 61 and the third lower arm 62, an N-channel MOSFET having a body diode is used.

[0118] The drain of the upper switch KH1 of the third upper arm 61 is connected to the high-voltage first terminal TH1, and the source of the upper switch KH1 of the third upper arm 61 is connected to the drain of the lower switch KH2 of the third upper arm 61. The source of the lower switch KH2 of the third upper arm 61 is connected to the low-voltage first terminal TL1 and the drain of the upper switch KL1 of the third lower arm 62. The drain of the lower switch KL2 of the third lower arm 62 is connected to the source of the upper switch KL1 of the third lower arm 62, and the source of the lower switch KL2 of the third lower arm 62 is connected to the high-voltage second terminal TH2 and the low-voltage second terminal TL2. The first end of the third reactor 64 is connected to the connection point of the source of the upper switch KH1 of the third upper arm 61 and the drain of the lower switch KH2. The second end of the third reactor 64 is connected to the first end of the third capacitor 65. The second end of the third capacitor 65 is connected to a connection point between the source of the upper switch KL1 and the drain of the lower switch KL2 of the third lower arm 62 .

[0119] In addition, in the present embodiment, the upper switch KH1 of the third upper arm 61 corresponds to the “upper arm first switch”, and the lower switch KH2 of the third upper arm 61 corresponds to the “upper arm second switch”. In addition, the upper switch KL1 of the third lower arm 62 corresponds to the “lower arm first switch”, and the lower switch KL2 of the third lower arm 62 corresponds to the “lower arm second switch”.

[0120] The control device 24 turns on and off the switches KH1, KH2, KL1, and KL2 of the third power conversion unit 60, similarly to the first power conversion unit 30, to make the third power conversion unit 60 in any state of Mode 1 to Mode 4. The control device 24 causes the third power conversion unit 60 to repeatedly perform a cycle of processing consisting of Mode 1 to Mode 4, thereby causing the third power conversion unit 60 to operate as either a step-up operation unit or a step-down operation unit.

[0121] Here, for example, similarly to the second embodiment, temperature increase control may be performed to synchronize the voltage increase operation of the first power conversion unit 30 with the voltage reduction operation of the second power conversion unit 40. In this case, how to control the remaining third power conversion unit 60 during temperature increase control becomes a problem. In this embodiment, the control device 24 stops the operation of the third power conversion unit 60 during temperature increase control. Thus, the generation of noise current due to the operation of the third power conversion unit 60 can be suppressed.

[0122] <Modification of the third embodiment> The control device 24 may operate the third power conversion unit 60 as either a voltage step-up unit or a voltage step-down unit instead of stopping the operation of the third power conversion unit 60 during the temperature increase control. In this case, the control device 24 preferably determines whether the third power conversion unit 60 is to operate as a voltage step-up unit or a voltage step-down unit based on the voltage VL between the low-voltage side terminals TL1 and TL2 and the voltage VH between the high-voltage side terminals TH1 and TH2.

[0123] Here, based on the previous Fig. 9 A method for determining whether the third power conversion unit 60 is to be operated as a step-up action unit or a step-down action unit based on the idea described in the description is described. When it is determined that the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 is above the first threshold value Va, the control device 24 preferably operates the third power conversion unit 60 as a step-up action unit. As a result, the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 is reduced. In addition, when the control device 24 determines that the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 is below the second threshold value Vb, it is preferable to operate the third power conversion unit 60 as a step-down action unit. As a result, the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 becomes higher.

[0124] When the control device 24 determines that the voltage VH between the terminals of the high-voltage side terminals TH1 and TH2 is greater than the third threshold value Vc, it is preferable that the third power conversion unit 60 is operated as a step-down operation unit. As a result, the voltage VH between the terminals of the high-voltage side terminals TH1 and TH2 is reduced. In addition, when the control device 24 determines that the voltage VH between the terminals of the high-voltage side terminals TH1 and TH2 is less than the fourth threshold value Vd, it is preferable that the third power conversion unit 60 is operated as a step-up operation unit. As a result, the voltage VH between the terminals of the high-voltage side terminals TH1 and TH2 becomes higher.

[0125] According to the present embodiment, in the temperature rise control, the inter-terminal voltage VL of the low-voltage side terminals TL1 and TL2 and the inter-terminal voltage VH of the high-voltage side terminals TH1 and TH2 can be controlled by using the third power conversion unit 60 which is asynchronous with the operation of the first power conversion unit 30 and the second power conversion unit 40. As a result, it is possible to suppress the occurrence of an overvoltage state and a low voltage state during the implementation of the temperature rise control.

[0126] <Fourth embodiment> Hereinafter, the fourth embodiment will be described focusing on the differences from the third embodiment.

[0127] In this embodiment, if Fig.17 As shown, the power conversion device 14 includes a fourth power conversion unit 70 in addition to the first power conversion unit 30, the second power conversion unit 40 and the third power conversion unit 60. Fig.17 In the figure, the control device 24 is omitted for convenience. Fig.16 The same structures are denoted by the same symbols.

[0128] The fourth power conversion unit 70 includes a fourth upper arm 71, a fourth lower arm 72, and a fourth resonant unit 73. The fourth upper arm 71 and the fourth lower arm 72 are a series connection body of a voltage-controlled semiconductor switch. The fourth resonant unit 73 is a series connection body of a fourth inductor 74 and a fourth capacitor 75. In the present embodiment, as the semiconductor switches of the fourth upper arm 71 and the fourth lower arm 72, an N-channel MOSFET having a body diode is used.

[0129] The drain of the upper switch RH1 of the fourth upper arm 71 is connected to the high-voltage first terminal TH1, and the source of the upper switch RH1 of the fourth upper arm 71 is connected to the drain of the lower switch RH2 of the fourth upper arm 71. The source of the lower switch RH2 of the fourth upper arm 71 is connected to the low-voltage first terminal TL1 and the drain of the upper switch RL1 of the fourth lower arm 72. The drain of the lower switch RL2 of the fourth lower arm 72 is connected to the source of the upper switch RL1 of the fourth lower arm 72, and the source of the lower switch RL2 of the fourth lower arm 72 is connected to the high-voltage second terminal TH2 and the low-voltage second terminal TL2. The first end of the fourth reactor 74 is connected to the connection point of the source of the upper switch RH1 of the fourth upper arm 71 and the drain of the lower switch RH2. The second end of the fourth reactor 74 is connected to the first end of the fourth capacitor 75. The second end of the fourth capacitor 75 is connected to a connection point between the source of the upper switch RL1 and the drain of the lower switch RL2 of the fourth lower arm 72 .

[0130] In addition, in the present embodiment, the upper switch RH1 of the fourth upper arm 71 corresponds to the “upper arm first switch”, and the lower switch RH2 of the fourth upper arm 71 corresponds to the “upper arm second switch”. In addition, the upper switch RL1 of the fourth lower arm 72 corresponds to the “lower arm first switch”, and the lower switch RL2 of the fourth lower arm 72 corresponds to the “lower arm second switch”.

[0131] The control device 24 turns on and off the switches RH1, RH2, RL1, and RL2 of the fourth power conversion unit 70, similarly to the first power conversion unit 30, to set the fourth power conversion unit 70 to any state of Mode 1 to Mode 4. The control device 24 causes the fourth power conversion unit 70 to repeatedly perform a cycle of processing consisting of Mode 1 to Mode 4, thereby causing the fourth power conversion unit 70 to operate as either a step-up operation unit or a step-down operation unit.

[0132] As in the previous Fig.15 As described in the effect of suppressing the generation of noise current in , when the operation of the power conversion unit performing the step-up operation is synchronized with the operation of the power conversion unit performing the step-down operation, the noise current may increase. Therefore, there is still room for improvement in reducing the noise current in the temperature increase control.

[0133] In the present embodiment, any two of the power conversion units 30, 40, 60, and 70 can be operated as boosting units, and the remaining two can be operated as step-down units. Therefore, in the temperature increase control, the control device 24 synchronizes the operation of the two power conversion units that perform the boosting operation, and synchronizes the operation of the two power conversion units that perform the step-down operation, instead of synchronizing the operation of the power conversion unit that performs the boosting operation with the operation of the power conversion unit that performs the step-down operation. Specifically, the control device 24 synchronizes the operation of the third power conversion unit 60 and the fourth power conversion unit 70 that perform the boosting operation, and synchronizes the operation of the first power conversion unit 30 and the second power conversion unit 40 that perform the step-down operation.

[0134] Fig.18 An operation example of the first power conversion unit 30 and the second power conversion unit 40 that perform a voltage step-down operation is shown. Fig.18 (a) to (d) correspond to the previous Figure 7 (a)~(d).

[0135] The upper switch QH1 of the first upper arm 31 is turned on and off synchronously with the lower switch SH2 of the second upper arm 41, and the lower switch QH2 of the first upper arm 31 is turned on and off synchronously with the upper switch SH1 of the second upper arm 41. In addition, the upper switch QL1 of the first lower arm 32 is turned on and off synchronously with the lower switch SL2 of the second lower arm 42, and the lower switch QL2 of the first lower arm 32 is turned on and off synchronously with the upper switch SL1 of the second lower arm 42.

[0136] Fig.19 (a) to (d) show the current paths flowing through the power conversion device 14 and the grounding member at the fifth time t5 to the eighth time t8 when the noise current is generated. Fig.13 The same structures are denoted by the same symbols.

[0137] At the fifth time t5, the upper switch QH1 of the first upper arm 31 and the lower switch SH2 of the second upper arm 41 are turned on, and the lower switch QH2 of the first upper arm 31 and the upper switch SH1 of the second upper arm 41 are turned off. The switches QL1 and QL2 of the first lower arm 32 and the switches SL1 and SL2 of the second lower arm 42 are not switched on and off.

[0138] In this case, the fifth outflow current ia5 flows through the floating capacitor 51 between the connection point of the source of the upper switch QH1 and the drain of the lower switch QH2 of the first upper arm 31 and the ground. The fifth outflow current ia5 is a current flowing in the direction from the power conversion device 14 toward the ground, and its magnitude is the same as the first outflow current ia1. In other words, the magnitude of the fifth outflow current ia5 is represented by the right side of the above formula (e1).

[0139] In addition, the fifth inflow current ib5 flows through the floating capacitor 54 between the connection point of the source of the upper switch SH1 and the drain of the lower switch SH2 of the second upper arm 41 and the ground. The fifth inflow current ib5 is a current flowing in the direction from the ground toward the power conversion device 14, and its magnitude is the same as the second inflow current ib2. In other words, the magnitude of the fifth inflow current ib5 is represented by the right side of the above formula (e4).

[0140] The fifth outflow current ia5 and the fifth inflow current ib5 are currents that flow in opposite directions to each other and circulate between the first power conversion unit 30 and the second power conversion unit 40 via the grounding member. In this case, since the current flowing out from the power conversion device 14 to the grounding member and the current flowing into the power conversion device 14 from the grounding member are offset, the difference between the magnitude of the fifth outflow current ia5 and the magnitude of the fifth inflow current ib5 becomes a noise current. Here, if it is assumed that the capacitance values ​​CH1 and CH2 of each floating capacitor 51 and 54 are the same, the magnitude of the fifth outflow current ia5 and the magnitude of the fifth inflow current ib5 are the same regardless of the values ​​of the inter-terminal voltages VH and VL. As a result, compared with the second embodiment, the difference between the magnitude of the fifth outflow current ia5 and the magnitude of the fifth inflow current ib5 can be reliably reduced, and the noise current can be reliably reduced.

[0141] At the sixth time t6, the upper switch QL1 of the first lower arm 32 and the lower switch SL2 of the second lower arm 42 are turned on, and the lower switch QL2 of the first lower arm 32 and the upper switch SL1 of the second lower arm 42 are turned off. The switches QH1 and QH2 of the first upper arm 31 and the switches SH1 and SH2 of the second upper arm 41 are not switched on and off.

[0142] In this case, the sixth outflow current ia6 flows through the floating capacitor 53 between the connection point of the source of the upper switch QL1 and the drain of the lower switch QL2 of the first lower arm 32 and the ground. The sixth outflow current ia6 is a current flowing in the direction from the power conversion device 14 toward the ground, and its magnitude is the same as the second outflow current ia2. In other words, the magnitude of the sixth outflow current ia6 is represented by the right side of the above formula (e3).

[0143] In addition, the sixth inflow current ib6 flows through the floating capacitor 52 between the connection point of the source of the upper switch SL1 and the drain of the lower switch SL2 of the second lower arm 42 and the ground. The sixth inflow current ib6 is a current flowing in the direction from the ground toward the power conversion device 14, and its magnitude is the same as the first inflow current ib1. In other words, the magnitude of the sixth inflow current ib6 is represented by the right side of the above formula (e2).

[0144] The sixth outflow current ia6 and the sixth inflow current ib6 are currents that flow in opposite directions to each other and circulate between the first power conversion unit 30 and the second power conversion unit 40 via the grounding member. In this case, since the current flowing out from the power conversion device 14 to the grounding member and the current flowing into the power conversion device 14 from the grounding member cancel each other out, the difference between the magnitude of the sixth outflow current ia6 and the magnitude of the sixth inflow current ib6 becomes a noise current. Here, if it is assumed that the capacitance values ​​CL2 and CL1 of each floating capacitor 52 and 53 are the same, the magnitude of the sixth outflow current ia6 and the magnitude of the sixth inflow current ib6 are the same regardless of the values ​​of the inter-terminal voltages VH and VL. As a result, compared with the second embodiment, the difference between the magnitude of the sixth outflow current ia6 and the magnitude of the sixth inflow current ib6 can be reliably reduced, and the noise current can be reliably reduced.

[0145] At the seventh time t7, the lower switch QH2 of the first upper arm 31 and the upper switch SH1 of the second upper arm 41 are turned on, and the upper switch QH1 of the first upper arm 31 and the lower switch SH2 of the second upper arm 41 are turned off. The switches QL1 and QL2 of the first lower arm 32 and the switches SL1 and SL2 of the second lower arm 42 are not switched on and off.

[0146] In this case, the seventh inflow current ib7 flows through the floating capacitor 51 between the connection point of the source of the upper switch QH1 and the drain of the lower switch QH2 of the first upper arm 31 and the ground. The seventh inflow current ib7 is a current flowing in the direction from the ground toward the power conversion device 14, and its magnitude is the same as the first outflow current ia1. In other words, the magnitude of the seventh inflow current ib7 is represented by the right side of the above formula (e1).

[0147] In addition, the seventh outflow current ia7 flows through the floating capacitor 54 between the connection point of the source of the upper switch SH1 and the drain of the lower switch SH2 of the second upper arm 41 and the ground. The seventh outflow current ia7 is a current flowing in the direction from the power conversion device 14 toward the ground, and its magnitude is the same as the second inflow current ib2. In other words, the magnitude of the seventh outflow current ia7 is represented by the right side of the above formula (e4).

[0148] The seventh outflow current ia7 and the seventh inflow current ib7 are currents that flow in opposite directions to each other and circulate between the first power conversion unit 30 and the second power conversion unit 40 via the grounding member. In this case, since the current flowing out from the power conversion device 14 to the grounding member and the current flowing into the power conversion device 14 from the grounding member cancel each other out, the difference between the magnitude of the seventh outflow current ia7 and the magnitude of the seventh inflow current ib7 becomes a noise current. Here, if it is assumed that the capacitance values ​​CH1 and CH2 of each floating capacitor 51 and 54 are the same, the magnitude of the seventh outflow current ia7 and the magnitude of the seventh inflow current ib7 are the same regardless of the values ​​of the inter-terminal voltages VH and VL. As a result, compared with the second embodiment, the difference between the magnitude of the seventh outflow current ia7 and the magnitude of the seventh inflow current ib7 can be reliably reduced, and the noise current can be reliably reduced.

[0149] At the eighth time t8, the lower switch QL2 of the first lower arm 32 and the upper switch SL1 of the second lower arm 42 are turned on, and the upper switch QL1 of the first lower arm 32 and the lower switch SL2 of the second lower arm 42 are turned off. The switches QH1 and QH2 of the first upper arm 31 and the switches SH1 and SH2 of the second upper arm 41 are not switched on and off.

[0150] In this case, the eighth inflow current ib8 flows through the floating capacitor 53 between the connection point of the source of the upper switch QL1 and the drain of the lower switch QL2 of the first lower arm 32 and the ground. The eighth inflow current ib8 is a current flowing in the direction from the ground toward the power conversion device 14, and its magnitude is the same as the second outflow current ia2. In other words, the magnitude of the eighth inflow current ib8 is represented by the right side of the above formula (e3).

[0151] In addition, the eighth outflow current ia8 flows through the floating capacitor 52 between the connection point of the source of the upper switch SL1 and the drain of the lower switch SL2 of the second lower arm 42 and the ground. The eighth outflow current ia8 is a current flowing in the direction from the power conversion device 14 toward the ground, and its magnitude is the same as the first inflow current ib1. In other words, the magnitude of the eighth outflow current ia8 is represented by the right side of the above formula (e2).

[0152] The eighth outflow current ia8 and the eighth inflow current ib8 are currents that flow in opposite directions to each other and circulate between the first power conversion unit 30 and the second power conversion unit 40 via the grounding member. In this case, since the current flowing out from the power conversion device 14 to the grounding member and the current flowing into the power conversion device 14 from the grounding member cancel each other out, the difference between the magnitude of the eighth outflow current ia8 and the magnitude of the eighth inflow current ib8 becomes a noise current. Here, assuming that the capacitance values ​​CL2 and CL1 of each floating capacitor 52 and 53 are the same, the magnitude of the eighth outflow current ia8 and the magnitude of the eighth inflow current ib8 are the same regardless of the values ​​of the inter-terminal voltages VH and VL. As a result, compared with the second embodiment, the difference between the magnitude of the eighth outflow current ia8 and the magnitude of the eighth inflow current ib8 can be reliably reduced, and the noise current can be reliably reduced.

[0153] The control device 24 synchronizes the operations of the third power conversion unit 60 and the fourth power conversion unit 70 that perform the step-down operation, similarly to synchronizing the operations of the first power conversion unit 30 and the second power conversion unit 40 that perform the step-down operation. Thus, even in the third power conversion unit 60 and the fourth power conversion unit 70 that perform the step-up operation, the noise current can be reliably reduced. Therefore, as a temperature increase control, the control device 24 synchronizes the operations of the third power conversion unit 60 and the fourth power conversion unit 70 that perform the step-up operation, and synchronizes the operations of the first power conversion unit 30 and the second power conversion unit 40 that perform the step-down operation, thereby reliably suppressing the generation of the noise current compared to the second embodiment.

[0154] <Other embodiments> In addition, each of the above-mentioned embodiments may be implemented with the following modifications.

[0155] The upper switch and the lower switch included in each of the upper and lower arms 31 , 32 , 41 , 42 , 61 , 62 , 71 , 72 are not limited to a single semiconductor switch, but may be a series connection of a plurality of semiconductor switches. Fig. 20 It is shown in the previous Figure 2 In the illustrated structure, the switches QH1 and QH2 of the first upper arm 31 and the switches QL1 and QL2 of the first lower arm 32 are each formed by a series connection of two N-channel MOSFETs. Thus, the switches QH1, QH2, QL1, and QL2 can be low-voltage elements.

[0156] The upper switch and the lower switch included in each of the upper and lower arms 31 , 32 , 41 , 42 , 61 , 62 , 71 , 72 may be constituted by a parallel connection of a plurality of semiconductor switches. Fig.21 It is shown in the previous Figure 2In the illustrated structure, the switches QH1 and QH2 of the first upper arm 31 and the switches QL1 and QL2 of the first lower arm 32 are each formed by a parallel connection of two N-channel MOSFETs. Thus, the switches QH1, QH2, QL1, and QL2 can be low current capacity elements.

[0157] The structure of the resonance part may be changed. Specifically, taking the first resonance part 33 as an example, the first end of the first capacitor 35 may be connected to the connection point of the source of the upper switch QH1 and the drain of the lower switch QH2 in the first upper arm part 31. The second end of the first capacitor 35 may be connected to the first end of the first reactor 34. The second end of the first reactor 34 may be connected to the connection point of the source of the upper switch QL1 and the drain of the lower switch QL2 in the first lower arm 32. As in the case of the first resonance part 33, the structures of the second resonance part 43, the third resonance part 63, and the fourth resonance part 73 may be changed.

[0158] In the fourth embodiment, the control device 24 is not limited to synchronizing the operations of the two power conversion units that perform the step-up operation and synchronizing the operations of the two power conversion units that perform the step-down operation. For example, the control device 24 may synchronize the step-up operation of the third power conversion unit 60 with the step-down operation of the first power conversion unit 30 and synchronize the step-up operation of the fourth power conversion unit 70 with the step-down operation of the second power conversion unit 40.

[0159] The power conversion device 14 may include more than five power conversion units. For example, when the power conversion device 14 includes six power conversion units, the number of pairs that can synchronize the operations of two power conversion units is three. In this case, various combinations of operations performed in the three pairs can be considered. Here, in order to reliably suppress the generation of noise current, it is desirable to synchronize the operations of the two boost operation units or synchronize the operations of the two step-down operation units in each pair.

[0160] Therefore, the control device 24 preferably synchronizes the voltage-increasing operation of the two voltage-increasing operation units in any two of the three pairs, and synchronizes the voltage-increasing operation of the two voltage-increasing operation units in the remaining one pair. In this case, the control device 24 preferably shortens the length of the period in which the voltage-increasing operation unit is set to Mode 2 or Mode 4 compared to the length of the period in which the voltage-increasing operation unit is set to Mode 2 or Mode 4 in order to obtain a balance of the power transmitted during the temperature-increasing control.

[0161] In addition, the control device 24 preferably synchronizes the voltage raising operation of the two voltage raising operation units in any one of the three pairs during the temperature raising control, and synchronizes the voltage lowering operation of the two voltage lowering operation units in the remaining two pairs. In this case, the control device 24 preferably makes the length of the period in which the voltage raising operation unit is set to mode 2 or mode 4 longer than the length of the period in which the voltage lowering operation unit is set to mode 2 or mode 4 in order to obtain a balance of the power transmitted during the temperature raising control.

[0162] According to the present embodiment, in each pair of two power conversion units capable of synchronizing operations, the operations of two voltage step-up operation units are synchronized, or the operations of two voltage step-down operation units are synchronized. Therefore, the generation of noise current can be reliably suppressed.

[0163] In the temperature increase control, the operation performed in the pair capable of synchronizing the operations of the two power conversion units is not limited to synchronizing the operations of the two voltage step-up operation units and synchronizing the operations of the two voltage step-down operation units.

[0164] In the temperature rise control, the control device 24 may synchronize the boosting action of the boosting action unit other than the boosting action unit that operates synchronously with the other boosting action units in each boosting action unit with the step-down action of the step-down action unit other than the step-down action unit that operates synchronously with the other step-down action units in each step-down action unit. In the case where the power conversion device 14 has a structure with 6 power conversion units, the control device 24 may synchronize the boosting action of two boosting action units in any one of the three pairs. Furthermore, the control device 24 may synchronize the step-down action of two step-down action units in any one of the remaining two pairs, and synchronize the boosting action of the boosting action unit and the step-down action of the step-down action unit in the other pair.

[0165] In addition, when the power conversion device 14 includes a structure of 8 power conversion units, the number of pairs in which the operations of two power conversion units can be synchronized is 4. In this case, the control device 24 preferably synchronizes the boosting operations of the two boosting operation units in any two of the four pairs, and synchronizes the step-down operations of the two step-down operation units in the remaining two pairs. Thus, the temperature rise control is performed while each boosting operation unit is operated synchronously with the other boosting operation units, and each step-down operation unit is operated synchronously with the other step-down operation units.

[0166] The power conversion unit is not limited to the first to fourth power conversion units 30, 40, 60, 70 including an upper arm unit, a lower arm unit, and a resonance unit. For example, the power conversion unit may be a non-insulated DC / DC converter. Fig. 22, an example is shown in which the power conversion device 14 includes a fifth power conversion unit 80 instead of the first power conversion unit 30, and includes a sixth power conversion unit 90 instead of the second power conversion unit 40. The fifth power conversion unit 80 is a non-insulated DC / DC converter of a step-up chopper type having a fifth inductor 81, a step-up switch 82, and a step-up diode 83. The sixth power conversion unit 90 is a non-insulated DC / DC converter of a step-down chopper type having a sixth inductor 91, a step-down switch 92, and a step-down diode 93. In this case, only a step-up operation is performed in the fifth power conversion unit 80, and only a step-down operation is performed in the sixth power conversion unit 90. In addition, the power conversion unit may also be a non-insulated DC / DC converter of a step-up and step-down chopper type.

[0167] The low-voltage side terminals TL1 and TL2 may be connected to a battery instead of being connected to the external charger 16. The high-voltage side terminals TH1 and TH2 may be connected to a DC side terminal of an ACDC converter instead of being connected to the battery 13.

[0168] The upper switch and the lower switch included in each of the upper and lower arms 31 , 32 , 41 , 42 , 61 , 62 , 71 , 72 are not limited to N-channel MOSFETs, and may be, for example, IGBTs to which freewheeling diodes are connected in anti-parallel.

[0169] · Hereinafter, characteristic structures extracted from the above-mentioned embodiments will be described. [Structure 1] A power conversion device, The power conversion device (14) has low-voltage side terminals (TL1, TL2) and high-voltage side terminals (TH1, TH2), and the power conversion device includes: a boosting operation unit, the boosting operation unit performing a boosting operation, the boosting operation boosting a voltage input from the low-voltage side terminal and outputting the voltage to the high-voltage side terminal; a step-down operation unit, the step-down operation unit performing a step-down operation for stepping down a voltage input from the high-voltage side terminal and outputting the voltage to the low-voltage side terminal; and A control unit (24) performs temperature increase control, wherein the temperature increase control causes the pressure increase action unit to perform the pressure increase action and causes the pressure reduction action unit to perform the pressure reduction action, thereby increasing the temperature of the temperature increase object (13). [Structure 2] The power conversion device as described in Structure 1, wherein: The invention comprises a plurality of power conversion units (30, 40, 60, 70), wherein the plurality of power conversion units have a series connection of an upper arm first switch (QH1, SH1, KH1, RH1) and an upper arm second switch (QH2, SH2, KH2, RH2), a series connection of a lower arm first switch (QL1, SL1, KL1, RL1) and a lower arm second switch (QL2, SL2, KL2, RL2), and a resonance unit (33, 43) which is a series connection of a reactor (34, 44, 64, 74) and a capacitor (35, 45, 65, 75), The high-voltage side terminals are a high-voltage side first terminal (TH1) on the high-potential side and a high-voltage side second terminal (TH2) on the low-potential side. The low-voltage side terminals are a low-voltage side first terminal (TL1) on the high potential side and a low-voltage side second terminal (TL2) on the low potential side. The resonator connects a connection point between the upper arm first switch and the upper arm second switch and a connection point between the lower arm first switch and the lower arm second switch. The upper arm first switch is connected to the high voltage side first terminal. The connection point of the second switch of the upper arm and the first switch of the lower arm is connected to the first terminal on the low voltage side. The second switch of the lower arm is connected to the second high-voltage side terminal and the second low-voltage side terminal. Each of the power conversion units is configured to operate as at least one of the voltage step-up operation unit and the voltage step-down operation unit by switching the upper arm first switch, the upper arm second switch, the lower arm first switch, and the lower arm second switch. The control unit performs the temperature increase control by operating at least one of the power conversion units as the voltage step-up operation unit and operating at least one of the power conversion units as the voltage step-down operation unit. [Structure 3] The power conversion device as described in Structure 2, wherein: When the temperature rise control is performed, the control unit makes the switching frequency of the upper arm first switch, the upper arm second switch, the lower arm first switch and the lower arm second switch included in the voltage boost action unit higher than the resonant frequency of the resonator included in the voltage boost action unit, and makes the switching frequency of the upper arm first switch, the upper arm second switch, the lower arm first switch and the lower arm second switch included in the voltage drop action unit higher than the resonant frequency of the resonator included in the voltage drop action unit. [Structure 4] The power conversion device as described in Structure 3, wherein: When the control unit operates each of the power conversion units as only one of the voltage step-up operation unit and the voltage step-down operation unit, the control unit sets the switching frequency to a frequency lower than the switching frequency during the temperature increase control and close to the resonance frequency. [Structure 5] A power conversion device as described in any one of Structures 2 to 4, wherein: The device comprises an acquisition unit, wherein the acquisition unit acquires a voltage between at least one of the low-voltage side terminal and the high-voltage side terminal, In the state where the upper arm second switch and the lower arm second switch are turned off and the upper arm first switch and the lower arm first switch are turned on is set as mode 1, The state where the upper arm second switch and the lower arm first switch are turned off and the upper arm first switch and the lower arm second switch are turned on is set as mode 2, The state where the upper arm first switch and the lower arm first switch are turned off and the upper arm second switch and the lower arm second switch are turned on is set as mode 3, When the state in which the upper arm first switch and the lower arm second switch are turned off and the upper arm second switch and the lower arm first switch are turned on is set as mode 4, In the above-mentioned temperature increase control, the above-mentioned control unit The step-up action unit is caused to repeatedly perform the processing consisting of the above-mentioned mode 1, the above-mentioned mode 2, the above-mentioned mode 3 and the above-mentioned mode 4 in order, and the step-down action unit is caused to repeatedly perform the processing consisting of the above-mentioned mode 1, the above-mentioned mode 4, the above-mentioned mode 3 and the above-mentioned mode 2 in order, Based on the obtained inter-terminal voltage, the length of at least one of the period during which the boost action is set to mode 2, the period during which the boost action is set to mode 4, the period during which the buck action is set to mode 2, and the period during which the buck action is set to mode 4 is set. [Structure 6] A power conversion device as described in any one of Structures 2 to 5, wherein: When performing the temperature increase control, a plurality of the power conversion units in each of the power conversion units can operate as the voltage increase operation unit, and a plurality of the power conversion units in each of the power conversion units can operate as the voltage decrease operation unit. The control unit synchronizes operations of the two voltage-increasing operation units and synchronizes operations of the two voltage-decreasing operation units during the temperature-increasing control. [Structure 7] The power conversion device as described in Structure 6, wherein: During the temperature rise control, the control unit synchronizes the voltage step-up operation of the voltage step-up operation units other than the voltage step-up operation units that operate synchronously with the other voltage step-up operation units with the voltage step-down operation of the voltage step-down operation units other than the voltage step-down operation units that operate synchronously with the other voltage step-down operation units. [Structure 8] A power conversion device as described in any one of Structures 2 to 5, wherein: The control unit synchronizes the voltage increasing operation of the voltage increasing operation unit with the voltage decreasing operation of the voltage decreasing operation unit during the temperature increasing control. [Structure 9] A power conversion device as described in any one of Structures 6 to 8, wherein: The control unit stops the operation of a power conversion unit other than a power conversion unit that operates in synchronization with the other power conversion units among the power conversion units during the temperature increase control. [Structure 10] A power conversion device as described in any one of Structures 6 to 8, wherein: The control unit operates, during the temperature increase control, a power conversion unit other than a power conversion unit that operates in synchronization with the other power conversion units among the power conversion units as the voltage step-up operation unit or the voltage step-down operation unit. [Structure 11] A power conversion device as described in any one of Structures 1 to 10, wherein: The high voltage side terminal is connected to the battery (13) which is the temperature increase object. As the voltage step-up operation, the voltage step-up operation unit steps up the voltage input from the low voltage terminal and outputs the stepped-up voltage to the battery. The step-down operation unit steps down the voltage output from the battery as the step-down operation, and outputs the stepped-down voltage to the low-voltage side terminal. [Structure 12] The power conversion device as described in structure 11, wherein: The low voltage side terminal is connected to a charging device (16). The voltage step-up operation unit charges the battery by stepping up the voltage output from the charging device and outputting the stepped-up voltage to the battery as the voltage step-up operation.

[0170] Although the present disclosure is described based on the embodiments, it should be understood that the present disclosure is not limited to the above-mentioned embodiments and structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and methods, and other combinations and methods containing only one element, above or below them, also belong to the scope and thought range of the present disclosure.

Claims

1. A power conversion device, the power conversion device (14) having low-voltage side terminals (TL1, TL2) and high-voltage side terminals (TH1, TH2), the power conversion device comprising: a boost operation unit, the boost operation unit performing a boost operation in which a voltage input from the low-voltage side terminal is boosted and the boosted voltage is output to the high-voltage side terminal; a step-down operation unit that performs a step-down operation in which a voltage input from the high-voltage side terminal is stepped down and the stepped-down voltage is output to the low-voltage side terminal; and A control unit (24) performs temperature increase control, wherein the temperature of the temperature increase target (13) is increased by causing the pressure increase action unit to perform the pressure increase action and causing the pressure decrease action unit to perform the pressure decrease action.

2. The power conversion device according to claim 1, characterized in that: The invention comprises a plurality of power conversion units (30, 40, 60, 70), each of which has a series connection of an upper arm first switch (QH1, SH1, KH1, RH1) and an upper arm second switch (QH2, SH2, KH2, RH2), a series connection of a lower arm first switch (QL1, SL1, KL1, RL1) and a lower arm second switch (QL2, SL2, KL2, RL2), and a resonance unit (33, 43) which is a series connection of a reactor (34, 44, 64, 74) and a capacitor (35, 45, 65, 75), The high-voltage side terminals are a high-voltage side first terminal (TH1) on the high-potential side and a high-voltage side second terminal (TH2) on the low-potential side, The low-voltage side terminals are a low-voltage side first terminal (TL1) on the high potential side and a low-voltage side second terminal (TL2) on the low potential side, The resonator connects a connection point between the upper arm first switch and the upper arm second switch and a connection point between the lower arm first switch and the lower arm second switch. The upper arm first switch is connected to the high voltage side first terminal, The connection point of the upper arm second switch and the lower arm first switch is connected to the low voltage side first terminal, The second switch of the lower arm is connected to the second terminal on the high voltage side and the second terminal on the low voltage side, Each of the power conversion units is configured to be able to operate as at least one of the voltage step-up operation unit and the voltage step-down operation unit by switching the upper arm first switch, the upper arm second switch, the lower arm first switch, and the lower arm second switch. The control unit performs the temperature increase control by operating at least one of the power conversion units as the voltage step-up operation unit and operating at least one of the power conversion units as the voltage step-down operation unit.

3. The power conversion device according to claim 2, characterized in that: When performing the temperature rise control, the control unit makes the switching frequency of the upper arm first switch, the upper arm second switch, the lower arm first switch and the lower arm second switch included in the voltage boost action unit higher than the resonant frequency of the resonance unit included in the voltage boost action unit, and makes the switching frequency of the upper arm first switch, the upper arm second switch, the lower arm first switch and the lower arm second switch included in the voltage drop action unit higher than the resonant frequency of the resonance unit included in the voltage drop action unit.

4. The power conversion device according to claim 3, characterized in that: When the control unit operates each of the power conversion units as only one of the voltage step-up operation unit and the voltage step-down operation unit, the control unit sets the switching frequency to a frequency lower than the switching frequency during the temperature increase control and close to the resonance frequency.

5. The power conversion device according to claim 2, characterized in that: The device comprises an acquisition unit, wherein the acquisition unit acquires a voltage between terminals of at least one of the low-voltage side terminal and the high-voltage side terminal, In the state where the upper arm second switch and the lower arm second switch are turned off and the upper arm first switch and the lower arm first switch are turned on is set as mode 1, The state where the upper arm second switch and the lower arm first switch are turned off and the upper arm first switch and the lower arm second switch are turned on is set as mode 2, The state where the upper arm first switch and the lower arm first switch are turned off and the upper arm second switch and the lower arm second switch are turned on is set as mode 3, When the state in which the upper arm first switch and the lower arm second switch are turned off and the upper arm second switch and the lower arm first switch are turned on is set as mode 4, In the temperature increase control, the control unit The step-up action unit is caused to repeatedly perform the processing consisting of the mode 1, the mode 2, the mode 3 and the mode 4 in order, and the step-down action unit is caused to repeatedly perform the processing consisting of the mode 1, the mode 4, the mode 3 and the mode 2 in order, Based on the acquired inter-terminal voltage, the length of at least one of the period during which the boost action is set to mode 2, the period during which the boost action is set to mode 4, the period during which the buck action is set to mode 2, and the period during which the buck action is set to mode 4 is set.

6. The power conversion device according to claim 2, characterized in that: When the temperature rise control is performed, a plurality of the power conversion units in each of the power conversion units can operate as the voltage step-up operation unit, and a plurality of the power conversion units in each of the power conversion units can operate as the voltage step-down operation unit. The control unit synchronizes operations of the two voltage increasing units and synchronizes operations of the two voltage decreasing units in the temperature increasing control.

7. The power conversion device according to claim 6, characterized in that: The control unit synchronizes the voltage increase operation of the voltage increase operation units other than the voltage increase operation units that operate synchronously with the other voltage increase operation units with the voltage reduction operation of the voltage reduction operation units other than the voltage reduction operation units that operate synchronously with the other voltage reduction operation units in the temperature increase control.

8. The power conversion device according to claim 2, characterized in that: The control unit synchronizes the pressure increasing operation of the pressure increasing operation unit with the pressure decreasing operation of the pressure decreasing operation unit during the temperature increasing control.

9. The power conversion device according to any one of claims 6 to 8, characterized in that: The control unit stops the operation of a power conversion unit other than a power conversion unit that operates in synchronization with other power conversion units among the power conversion units during the temperature increase control.

10. The power conversion device according to any one of claims 6 to 8, characterized in that: The control unit operates, during the temperature increase control, a power conversion unit other than a power conversion unit that operates in synchronization with other power conversion units among the power conversion units as the voltage step-up operation unit or the voltage step-down operation unit.

11. The power conversion device according to claim 1, wherein: The high voltage side terminal is connected to the battery (13) which is the temperature increase target. As the boost operation, the boost operation unit boosts the voltage input from the low voltage side terminal and outputs the boosted voltage to the battery. The step-down operation unit steps down the voltage output from the battery as the step-down operation, and outputs the stepped-down voltage to the low-voltage side terminal.

12. The power conversion device according to claim 11, characterized in that: The low-voltage side terminal is connected to a charging device (16), The voltage step-up operation unit steps up the voltage output from the charging device as the voltage step-up operation, and outputs the stepped-up voltage to the battery, thereby charging the battery.

Images