Power conversion device, power conversion method

Abstract

This invention provides a technology for power conversion devices installed in vehicles capable of supplying power to external sources, which can suppress a decrease in conversion efficiency even when there are sharp changes in power demand. [Solution] The power conversion device 1 comprises a power conversion circuit 10 that performs power conversion using a plurality of switching elements 11, and a control circuit 20 that can select one of a plurality of control modes and controls the operation of each switching element 11 of the power conversion circuit 10 according to the selected control mode. The power conversion circuit 10 can convert the output power of the battery 2 mounted on the vehicle 100 and output it to a power load 6, which is an external load connected to the vehicle 100, and can also convert the power supplied from the power system 7, which is an external power source connected to the vehicle 100, and output it to the battery 2. The control circuit 20 acquires the state of change in power demand of the power load 6 and selects a control mode based on the acquired state of change in power demand.

Description

Technical Field

[0001] The present invention relates to a power conversion device mounted on a vehicle and a power conversion method using the same. Background Art

[0002] In recent years, electric vehicles such as PHEVs (Plug-in Hybrid Electric Vehicles) and BEVs (Battery Electric Vehicles) have been widely used. These vehicles are equipped with an on-vehicle battery that can be charged with power supplied from a commercial power source or a dedicated charger, and can run by driving a motor using the power stored in the on-vehicle battery. In addition, there is also known a technology that realizes a system that can be used for purposes other than motor driving by supplying the power stored in the on-vehicle battery of such an electric vehicle to the outside of the vehicle. For example, systems such as V2L (Vehicle to Load) that realizes power supply to electric devices connected to a vehicle, V2H (Vehicle to Home) that realizes power supply to an entire general house such as a detached house, and V2G (Vehicle to Grid) that realizes power supply to a power grid have been popularized or proposed. These systems are collectively referred to as V2X.

[0003] Generally, since the power output from an on-vehicle battery is high-voltage DC power, it cannot be used as it is in household electric devices or power grids. Therefore, in order to realize V2X, it is necessary to mount a power conversion device on the vehicle that can convert the output power of the on-vehicle battery in accordance with the requirements of household electric devices and power grids. Such power conversion devices for electric vehicles are required to have high conversion efficiency and resistance to load fluctuations.

[0004] Regarding power conversion devices for electric vehicles, for example, Patent Document 1 is known. Patent Document 1 describes a power supply system having a DC / DC conversion unit in which three isolation converter circuits having a full bridge circuit are connected in parallel, and a V2H control unit that controls this DC / DC conversion unit, wherein the V2H control unit receives load amount information corresponding to the operating status of multiple electrical appliances in the home from a higher-level controller that monitors the operating status of those appliances, and switches the operation of the DC / DC conversion unit to a first to fourth operation based on the received load amount information. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-144659 [Overview of the project] [Problems that the invention aims to solve]

[0006] The power supply system described in Patent Document 1 controls the operation of the DC / DC converter based on load information representing the magnitude of power demand. Therefore, when there is a sudden change in power demand, it is not able to respond adequately, resulting in a problem of reduced conversion efficiency.

[0007] The present invention has been made in view of the above problems, and its main objective is to provide a technology that can suppress a decrease in conversion efficiency even when there is a sudden change in power demand in a power conversion device mounted on a vehicle capable of supplying power to the outside. [Means for solving the problem]

[0008] The power conversion device according to the present invention is mounted on a vehicle and comprises a power conversion circuit having a plurality of switching elements and performing power conversion using the plurality of switching elements, and a control circuit that can select one of a plurality of control modes and controls the operation of each switching element of the power conversion circuit according to the selected control mode, wherein the power conversion circuit is capable of converting the output power of a battery mounted on the vehicle and outputting it to an external load connected to the vehicle, and converting the power supplied from an external power source connected to the vehicle and outputting it to the battery, and the control circuit acquires the state of change in the power demand of the external load and selects the control mode based on the acquired state of change in power demand. The power conversion method according to the present invention uses a power conversion device capable of converting the output power of a battery mounted on a vehicle and outputting it to an external load connected to the vehicle, and converting the power supplied from an external power source connected to the vehicle and outputting it to the battery, and acquires the state of change in the power demand of the external load, selects one of a plurality of control modes based on the acquired state of change in power demand, and controls the operation of a plurality of switching elements of the power conversion device according to the selected control mode. [Effects of the Invention]

[0009] According to the present invention, a technology is available that can suppress a decrease in conversion efficiency even when there is a sudden change in power demand in a power conversion device mounted on a vehicle capable of supplying power to an external source.

[0010] Furthermore, issues, configurations, and effects other than those mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0011] [Figure 1] This diagram shows the configuration of a power conversion device according to the first embodiment of the present invention. [Figure 2] This is a flowchart showing the processing details of the control circuit in the first embodiment of the present invention. [Figure 3] It is a diagram showing an example of a first map. [Figure 4] It is a flowchart showing the processing content of a control circuit in a second embodiment of the present invention. [Figure 5] It is a diagram showing an example of a second map. [Figure 6] It is a diagram showing the configuration of a power converter according to a third embodiment of the present invention. [Figure 7] It is a flowchart showing the processing content of a control circuit in a third embodiment of the present invention. [Figure 8] It is a diagram showing an example of a third map. [Figure 9] It is a diagram showing the configuration of a power converter according to a fourth embodiment of the present invention. [Figure 10] It is a flowchart showing the processing content of a control circuit in a fourth embodiment of the present invention. [Figure 11] It is a diagram showing an example of a fourth map. [Figure 12] It is a flowchart showing the processing content of a control circuit in a fifth embodiment of the present invention. [Figure 13] It is a diagram showing an example where the duty ratio is changed for each control mode. [Figure 14] It is a diagram showing an example where the switching frequency is changed for each control mode. DETAILED DESCRIPTION OF EMBODIMENTS

[0012] (First Embodiment) Figure 1 is a diagram showing the configuration of a power converter according to a first embodiment of the present invention. A power converter 1 shown in Figure 1 is mounted on a vehicle 100 that is an electric vehicle, and includes a power conversion circuit 10 and a control circuit 20.

[0013] The power conversion circuit 10 is connected to the battery 2 mounted on the vehicle 100. The power conversion circuit 10 is also connected to the electric vehicle supply equipment (EVSE) 5 via an inlet 4 provided on the vehicle 100. The electric vehicle supply equipment 5 is installed near the parking area where the vehicle 100 can be parked and is a device that provides power supplied from the power grid 7 to the vehicle 100 to charge the battery 2, and also discharges the battery 2 to supply power to the power load 6 and the power grid 7 using the power provided by the vehicle 100. The power load 6 includes, for example, various household electrical appliances used in a building adjacent to the parking area.

[0014] In this embodiment, the power input and output between the vehicle 100, the power supply device 5, the power load 6, and the power system 7 are assumed to be AC ​​power. That is, the power conversion circuit 10 is a bidirectional DC / AC converter that is directly or indirectly connected to the battery 2, the power load 6, and the power system 7, and is capable of converting power between them. When the vehicle 100 supplies power to the power load 6 or the power system 7, the power load 6 or the power system 7 acts as an external load for the vehicle 100 and the battery 2. On the other hand, when the battery 2 is being charged, the power system 7 acts as an external power source for the vehicle 100 and the battery 2.

[0015] The power conversion circuit 10 is composed of a combination of multiple switching elements 11 and a transformer 12. The switching elements 11 are composed of semiconductor elements that can switch according to a gate signal, such as IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). Figure 1 shows an example of the power conversion circuit 10, which consists of two parallel combinations of isolated DC / DC converters and DC / AC inverters, but other configurations are also possible. The power conversion circuit 10 can be realized with any circuit configuration as long as bidirectional power conversion can be performed between the battery 2, the power load 6 and the power system 7 via the power supply device 5.

[0016] Battery 2 is connected to a battery management device 3. The battery management device 3 detects the voltage, input / output current, state of charge (SOC), state of health (SOH), etc., of battery 2, and manages battery 2 based on these values.

[0017] The control circuit 20 is a circuit that controls the power converter 1 and includes a storage unit 21, a detection unit 22, a calculation unit 23, and a drive control unit 24. The control circuit 20 is configured using, for example, a microcontroller, and the microcontroller can realize the functions of the storage unit 21, the detection unit 22, the calculation unit 23, and the drive control unit 24 by executing a predetermined program.

[0018] The memory unit 21 stores information about multiple control modes for controlling the operation of multiple switching elements 11 in the power conversion circuit 10. For example, multiple control modes with different operating patterns for each switching element 11 can be defined in advance, and information about the operation of the switching elements 11 for each control mode can be stored in the memory unit 21. Specific examples of the operation of the switching elements 11 for each control mode will be described later.

[0019] A current sensor 13 and a voltage sensor 14 are provided between the power conversion circuit 10 and the inlet 4. The detection unit 22 acquires measurement signals from the current sensor 13 and the voltage sensor 14, and obtains the current and voltage of the AC power input and output to the power conversion circuit 10 from these measurement signals. Then, based on the acquired AC power current and voltage, it detects the power demand of the power load 6.

[0020] The calculation unit 23 determines the control mode of the power conversion circuit 10 based on the information stored in the storage unit 21 and the power demand detected by the detection unit 22. The drive control unit 24 controls the drive of each switching element 11 of the power conversion circuit 10 according to the control mode determined by the calculation unit 23.

[0021] The control circuit 20 can select one of several control modes through the processing of the memory unit 21, detection unit 22, calculation unit 23, and drive control unit 24 described above, and control the operation of each switching element of the power conversion circuit 10 to perform power conversion between the battery 2 and the power load 6 according to the selected control mode.

[0022] Figure 2 is a flowchart showing the processing details of the control circuit 20 in the first embodiment of the present invention. In this embodiment, the control circuit 20 controls the operation of the power conversion circuit 10 by executing the processing shown in the flowchart of Figure 2 at predetermined intervals, for example. In this embodiment, it is assumed that the power conversion device 1 converts the DC power of the battery 2 into AC power and outputs it to the power load 6 via the power supply device 5, thereby supplying power from the vehicle 100 to the power load 6.

[0023] In step S10, the detection unit 22 acquires the power demand of the power load 6. Here, as described above, the current and voltage of the AC power input and output to the power conversion circuit 10 are determined from the measurement signals of the current sensor 13 and the voltage sensor 14, and the power demand of the power load 6 is acquired based on these.

[0024] In step S20, the calculation unit 23 calculates the state of change in power demand based on the power demand of the power load 6 obtained in step S10. Here, the state of change in power demand over time is calculated using the power demand values ​​obtained in the past and the power demand values ​​of the current power demand. Specifically, the amount of change in power demand per unit time (power demand rate), the amount of change per unit time (power demand acceleration), and the amount of change per unit time (power demand jerk) can be calculated as the state of change in power demand. Note that the values ​​to be used can be arbitrarily selected by referring to the history of past power demand and simulation results.

[0025] In step S30, the calculation unit 23 acquires map information (hereinafter referred to as the "first map") from the information stored in the storage unit 21, which represents the correspondence between the power demand change state and the control mode. Then, by referring to the acquired first map, the calculation unit selects one of the control modes from among several control modes by identifying the control mode corresponding to the power demand change state calculated in step S20.

[0026] Figure 3 shows an example of the first map referenced in step S30. In Figure 3, (a) shows an example of the first map representing the correspondence between power demand velocity and control mode when power demand velocity is used as the state of change in power demand, (b) shows an example of the first map representing the correspondence between power demand acceleration and control mode when power demand acceleration is used as the state of change in power demand, and (c) shows an example of the first map representing the correspondence between power demand jerk and control mode when power demand jerk is used as the state of change in power demand.

[0027] If the power demand rate is calculated as the state of change in power demand in step S20, then in step S30, the first map shown in Figure 3(a) is referred to, for example. Then, if the power demand rate value V is 0 or greater and less than 250 kW / ms, control mode C is selected; if it is 250 kW / ms or greater and less than 500 kW / ms, control mode B is selected; and if it is 500 kW / ms or greater, control mode A is selected.

[0028] If the power demand acceleration is calculated as the state of change in power demand in step S20, then in step S30, the first map shown in Figure 3(b) is referred to. Then, if the value of power demand acceleration A is 0 or greater and 50 kW / ms, 2 If less than 50kW / ms, control mode C is used. 2 The above and 100kW / ms 2 If less than 100kW / ms, control mode B is used. 2 In the above cases, select control mode A.

[0029] If the power demand jerk is calculated as the state of change in power demand in step S20, then in step S30, the first map shown in Figure 3(c) is referred to. Then, the power demand jerk value J is greater than or equal to 0 and 30 kW / ms. 3 If less than 30kW / ms, control mode C is used. 3 The above and 60kW / ms 3 If less than 60kW / ms, control mode B is used. 3 In the above cases, select control mode A.

[0030] In the examples above, one of three control modes A, B, and C is selected, but the number of selectable control modes is not limited to these; there may be two, four, or more. Also, the numerical values ​​for the power demand change state corresponding to the selection conditions for each control mode in the examples above are just examples, and other values ​​may be used.

[0031] Returning to the explanation of Figure 2, step S40 determines which control mode was selected in step S30. Here, for example, in the first map example shown in Figure 3, if control mode A is selected, the process proceeds to step S50; if control mode B is selected, it proceeds to step S60; and if control mode C is selected, it proceeds to step S70. Note that the flowchart in Figure 2 shows an example where there are three selectable control modes, and the number of branches from step S40 onwards is set to three accordingly. However, as mentioned above, there may be cases where there are more than three selectable control modes. In that case, the number of branches from step S40 onwards should be set according to the number of selectable control modes.

[0032] In steps S50, S60, and S70, the drive control unit 24 performs drive control of each switching element 11 according to control modes A, B, and C, respectively. Here, for example, a gate signal corresponding to the control mode is output to the gate terminal of each switching element 11, causing each switching element 11 to switch. As a result, the power conversion circuit 10 performs power conversion operation according to the selected control mode.

[0033] After executing any of steps S50, S60, or S70, the process shown in the flowchart in Figure 2 is terminated.

[0034] According to the first embodiment of the present invention described above, the following effects are achieved.

[0035] (1) The power converter 1 is mounted on the vehicle 100 and includes a power conversion circuit 10 having a plurality of switching elements 11 and performing power conversion using the plurality of switching elements 11, and a control circuit 20 that can select one of a plurality of control modes and controls the operation of each switching element 11 of the power conversion circuit 10 according to the selected control mode. The power conversion circuit 10 can convert the output power of the battery 2 mounted on the vehicle 100 and output it to a power load 6, which is an external load connected to the vehicle 100, and can also convert the power supplied from the power system 7, which is an external power source connected to the vehicle 100, and output it to the battery 2. The control circuit 20 acquires the state of change in power demand of the power load 6 (steps S10, S20) and selects a control mode based on the acquired state of change in power demand (step S30). In this way, since the control mode can be selected according to the state of change in power demand, even if a sudden change in power demand occurs, the decrease in the conversion efficiency of the power converter 1 can be suppressed by selecting an appropriate control mode.

[0036] (2) In step S20, the control circuit 20 can acquire the power demand rate (first change), which is the change in power demand per unit time; the power demand acceleration (second change), which is the change in the first change per unit time; or the power demand jerk (third change), which is the change in the second change per unit time, as the power demand change state. In this way, an appropriate change can be acquired as the power demand change state according to the trend of change in power demand, and this can be used to select a control mode.

[0037] (Second embodiment) Next, a power conversion device according to a second embodiment of the present invention will be described. In this embodiment, in addition to the change in the power demand state of the power load 6 described in the first embodiment, an example will be described in which a control mode is selected based on the magnitude of the power demand of the power load 6. Note that the power conversion device of this embodiment has the same configuration as the power conversion device 1 of Figure 1 described in the first embodiment. Therefore, the second embodiment of the present invention will be described below using the configuration of the power conversion device 1 of Figure 1.

[0038] Figure 4 is a flowchart showing the processing details of the control circuit 20 in the second embodiment of the present invention. In this embodiment, the control circuit 20 controls the operation of the power conversion circuit 10 by executing the processing shown in the flowchart of Figure 4 at predetermined intervals, for example. In this embodiment as in the first embodiment, the power conversion device 1 converts the DC power of the battery 2 into AC power and outputs it to the power load 6 via the power supply device 5, thereby supplying power from the vehicle 100 to the power load 6.

[0039] In steps S10 to S40, the same processes as those shown in Figure 2 in the first embodiment are performed. In step S40, if control mode A is selected in the first map, the process proceeds to step S50; if control mode B is selected, it proceeds to step S60; and if control mode C is selected, it proceeds to step S80. If the process proceeds to steps S50 or S60, the same processes as those shown in Figure 2 are performed, and the process shown in the flowchart of Figure 4 is completed.

[0040] In step S80, the calculation unit 23 acquires map information (hereinafter referred to as the "second map") from the information stored in the storage unit 21, which represents the correspondence between the magnitude of the power demand of the power load 6 and the control mode. Then, by referring to the acquired second map and identifying the control mode corresponding to the magnitude of the power demand acquired in step S10, one of the control modes is selected from among several control modes.

[0041] Figure 5 shows an example of a second map referenced in step S80. In step S80, for example, the second map shown in Figure 5 is referenced. Then, control mode C is selected if the output power P of the power conversion circuit 10, which represents the magnitude of the power demand of the power load 6, is 0 or more and less than 3kW, 3kW or more and less than 6kW, or 6kW or more and less than 9kW; control mode D is selected if it is 9kW or more and less than 12kW, or 12kW or more and less than 15kW; and control mode E is selected if it is 15kW or more.

[0042] In the examples above, one of three control modes C, D, and E is selected, but the number of selectable control modes is not limited to these; there may be two, four, or more. Also, the numerical values ​​for the magnitude of power demand corresponding to the selection conditions for each control mode in the examples above are just examples, and other values ​​may be used.

[0043] Returning to the explanation of Figure 4, step S90 determines which control mode was selected in step S80. Here, for example, in the example of the second map shown in Figure 5, if control mode C is selected, the process proceeds to step S100; if control mode D is selected, it proceeds to step S110; and if control mode E is selected, it proceeds to step S120. Note that the flowchart in Figure 4 shows an example where there are three selectable control modes, and the number of branches from step S90 onwards is set to three accordingly. However, as mentioned above, there may be cases where there are more than three selectable control modes. In that case, the number of branches from step S90 onwards should be set according to the number of selectable control modes.

[0044] In steps S100, S110, and S120, the drive control unit 24 performs drive control of each switching element 11 according to control modes C, D, and E, respectively. Here, for example, a gate signal corresponding to the control mode is output to the gate terminal of each switching element 11, causing each switching element 11 to switch. As a result, the power conversion circuit 10 performs power conversion operation according to the selected control mode.

[0045] After executing any of steps S100, S110, or S120, the process shown in the flowchart in Figure 4 is terminated.

[0046] According to the second embodiment of the present invention described above, the control circuit 20 further acquires the magnitude of the power demand of the power load 6, which is an external load (step S10), and selects a control mode based on the acquired change state and magnitude of the power demand (steps S30, S80). In this way, in addition to the change state of the power demand, the magnitude of the power demand can also be considered, and an appropriate control mode can be selected.

[0047] (Third embodiment) Next, a power conversion device according to a third embodiment of the present invention will be described. In this embodiment, in addition to the change in power demand state of the power load 6 described in the first embodiment, an example will be described in which the control mode is selected based on the charging and supply state of the vehicle 100, that is, the power input and output state to the power conversion circuit 10.

[0048] Figure 6 shows the configuration of a power converter according to a third embodiment of the present invention. The power converter 1A shown in Figure 6 is mounted on a vehicle 100, which is an electric vehicle, and comprises a power conversion circuit 10 and a control circuit 20A similar to those described in Figure 1 in the first embodiment.

[0049] The control circuit 20A is a circuit that controls the power converter 1A, and in addition to the storage unit 21, detection unit 22, calculation unit 23, and drive control unit 24 similar to those described in Figure 1 in the first embodiment, it also has a determination unit 25. The control circuit 20A is configured using, for example, a microcontroller, and the microcontroller can realize the functions of the storage unit 21, detection unit 22, calculation unit 23, drive control unit 24, and determination unit 25 by executing a predetermined program.

[0050] In this embodiment, the determination unit 25 acquires information regarding the input and output current of the battery 2 from the battery management device 3 and determines the charging and power supply status of the vehicle 100 based on that information. The calculation unit 23 determines the control mode of the power conversion circuit 10 based on the information stored in the storage unit 21, the power demand detected by the detection unit 22, and the charging and power supply status of the vehicle 100 determined by the determination unit 25.

[0051] Figure 7 is a flowchart showing the processing details of the control circuit 20A in the third embodiment of the present invention. In this embodiment, the control circuit 20A controls the operation of the power conversion circuit 10 by executing the processing shown in the flowchart of Figure 7 at predetermined intervals, for example. In this embodiment, unlike the first and second embodiments described above, the power conversion device 1A either converts the DC power of the battery 2 into AC power and outputs it to the power load 6 via the power supply device 5 to supply power from the vehicle 100 to the power load 6, or converts the AC power supplied from the power system 7 via the power supply device 5 into DC power and outputs it to the battery 2 to charge the battery 2.

[0052] In steps S10 and S20, the same processes as those described in Figure 2 of the first embodiment are performed, respectively. In step S21, the determination unit 25 determines the charging and power supply status of the vehicle 100. Here, as described above, by obtaining information on the input and output current of the battery 2 from the battery management device 3, it is possible to determine whether the vehicle 100 is supplying power to the power load 6, or whether the vehicle 100 is receiving power from the power system 7 to charge the battery 2.

[0053] In step S31, the calculation unit 23 acquires map information (hereinafter referred to as the "third map") from the information stored in the storage unit 21, which represents the correspondence between the power demand change state and the charging / supplying state of the vehicle 100 and the control mode. Then, by referring to the acquired third map, the calculation unit 23 identifies the control mode that corresponds to the power demand change state calculated in step S20 and the charging / supplying state of the vehicle 100 determined in step S21, and selects one of the control modes from among several control modes.

[0054] Figure 8 shows an example of a third map referenced in step S31. In step S31, for example, the third map shown in Figure 8 is referenced. If the power demand rate value V is 0 or greater and less than 250 kW / ms, control mode C is selected if battery 2 is being charged, and control mode B is selected if power is being supplied to power load 6. Also, if the power demand rate value V is 250 kW / ms or greater and less than 500 kW / ms, control mode B is selected regardless of whether battery 2 is being charged or power is being supplied to power load 6. Furthermore, if the power demand rate value V is 500 kW / ms or greater, control mode A is selected regardless of whether battery 2 is being charged or power is being supplied to power load 6.

[0055] In the examples above, one of three control modes A, B, and C is selected, but the number of selectable control modes is not limited to these; there may be two or four or more. Also, the numerical values ​​of power demand rate corresponding to the selection conditions for each control mode in the examples above are examples only, and other values ​​may be used. Furthermore, instead of power demand rate, power demand acceleration or power demand jerk described in the first embodiment may be used.

[0056] Returning to the explanation of Figure 7, from step S40 onward, the same processes as those described in Figure 2 in the first embodiment are performed. After executing any of steps S50, S60, or S70, the process shown in the flowchart of Figure 7 is terminated.

[0057] According to the third embodiment of the present invention described above, the control circuit 20A further acquires the charging and supplying state, which is the power input / output state to the power conversion circuit 10 (step S21), and selects a control mode based on the acquired power demand change state and charging and supplying state (step S31). In this way, in addition to the power demand change state, the charging and supplying state can also be considered, and an appropriate control mode can be selected.

[0058] (Fourth embodiment) Next, a power conversion device according to a fourth embodiment of the present invention will be described. In this embodiment, an example will be described in which the control mode is selected based on the state of charge (SOC) of the battery 2, in addition to the change in power demand state of the power load 6 described in the first embodiment.

[0059] Figure 9 shows the configuration of a power converter according to a fourth embodiment of the present invention. The power converter 1B shown in Figure 9 is mounted on a vehicle 100, which is an electric vehicle, and comprises a power conversion circuit 10 and a control circuit 20B similar to those described in Figure 1 in the first embodiment.

[0060] The control circuit 20B is a circuit that controls the power converter 1B, and instead of the detection unit 22 shown in Figure 1 as described in the first embodiment, it has a detection unit 22B. The control circuit 20B is configured using, for example, a microcontroller, and the microcontroller can realize the functions of the storage unit 21, the detection unit 22B, the calculation unit 23, and the drive control unit 24 by executing a predetermined program.

[0061] In this embodiment, the detection unit 22B, similar to the detection unit 22 in the first embodiment, acquires measurement signals from the current sensor 13 and the voltage sensor 14, and from these measurement signals acquires the current and voltage of the AC power input and output to the power conversion circuit 10 to detect the power demand of the power load 6. Furthermore, it acquires information regarding the charge state of the battery 2 from the battery management device 3 and detects the charge state (SOC) of the battery 2 based on that information. The calculation unit 23 determines the control mode of the power conversion circuit 10 based on the information stored in the storage unit 21 and the power demand and charge state of the battery 2 detected by the detection unit 22B.

[0062] Figure 10 is a flowchart showing the processing details of the control circuit 20B in the fourth embodiment of the present invention. In this embodiment, the control circuit 20B controls the operation of the power conversion circuit 10 by executing the processing shown in the flowchart of Figure 10 at predetermined intervals, for example. In this embodiment as well, as in the first and second embodiments, the power conversion device 1 converts the DC power of the battery 2 into AC power and outputs it to the power load 6 via the power supply device 5, thereby supplying power from the vehicle 100 to the power load 6.

[0063] In steps S10 and S20, the same processes as those shown in Figure 2 of the first embodiment are performed, respectively. In step S22, the detection unit 22B obtains the state of charge (SOC) of the battery 2 from the battery management device 3.

[0064] In step S32, the calculation unit 23 acquires map information (hereinafter referred to as the "fourth map") from the information stored in the storage unit 21, which represents the power demand change state and the correspondence between the battery 2's SOC and the control mode. Then, by referring to the acquired fourth map, the calculation unit 23 identifies the control mode that corresponds to the power demand change state calculated in step S20 and the battery 2's SOC acquired in step S22, and selects one of the control modes from among several control modes.

[0065] Figure 11 shows an example of the fourth map referenced in step S32. In step S32, for example, the fourth map shown in Figure 11 is referenced. Then, if the power demand rate value V is 0 or greater and less than 250 kW / ms, control mode A is selected if the SOC of battery 2 is 0% or greater and less than 20%, control mode B is selected if the SOC of battery 2 is 20% or greater and less than 60%, and control mode C is selected if the SOC of battery 2 is 60% or greater. Furthermore, if the power demand rate value V is 250 kW / ms or greater and less than 500 kW / ms, control mode A is selected if the SOC of battery 2 is 0% or greater and less than 60%, and control mode B is selected if the SOC of battery 2 is 60% or greater. In addition, if the power demand rate value V is 500 kW / ms or greater, control mode A is selected regardless of the SOC of battery 2.

[0066] In the examples above, one of three control modes A, B, and C is selected, but the number of selectable control modes is not limited to these; there may be two or four or more. Also, the numerical values ​​of power demand rate corresponding to the selection conditions for each control mode in the examples above are examples only, and other values ​​may be used. Furthermore, instead of power demand rate, power demand acceleration or power demand jerk described in the first embodiment may be used.

[0067] Returning to the explanation of Figure 10, from step S40 onward, the same processes as those described in Figure 2 in the first embodiment are performed. After executing any of steps S50, S60, or S70, the process shown in the flowchart of Figure 10 is terminated.

[0068] According to the fourth embodiment of the present invention described above, the control circuit 20B further acquires the state of charge (SOC) of the battery 2 (step S22), and selects a control mode based on the acquired change in power demand and the charge state of the battery 2 (step S32). In this way, in addition to the change in power demand, the charge state of the battery 2 can also be considered, and an appropriate control mode can be selected.

[0069] (Fifth embodiment) Next, a power conversion device according to the fifth embodiment of the present invention will be described. In this embodiment, an example will be described in which the timing for changing the control of each switching element 11 of the power conversion circuit 10 according to the selected control mode is determined based on the current value of the power conversion circuit 10. The power conversion device of this embodiment has the same configuration as the power conversion device 1 of Figure 1 described in the first embodiment. Therefore, the fifth embodiment of the present invention will be described below using the configuration of the power conversion device 1 of Figure 1.

[0070] Figure 12 is a flowchart showing the processing details of the control circuit 20 in the fifth embodiment of the present invention. In this embodiment, the control circuit 20 controls the operation of the power conversion circuit 10 by executing the processing shown in the flowchart of Figure 12 at predetermined intervals, for example. In this embodiment as well, as in the first, second, and fourth embodiments, the power conversion device 1 converts the DC power of the battery 2 into AC power and outputs it to the power load 6 via the power supply device 5, thereby supplying power from the vehicle 100 to the power load 6.

[0071] In step S1, the detection unit 22 acquires the current value of the AC power that is input and output to the power conversion circuit 10 from the measurement signal of the current sensor 13.

[0072] In step S2, the current value obtained in step S1 is compared with a predetermined threshold to determine whether the current value is less than the threshold. If the current value is less than the threshold, the process proceeds to step S10; otherwise, it returns to step S1. This ensures that if the current value of the AC power input and output to the power conversion circuit 10 is greater than or equal to the threshold, the processing from step S10 onward is not executed. This maintains the control state of each switching element 11 regardless of changes in power demand, and the control state of each switching element 11 is changed when the current value of the AC power input and output to the power conversion circuit 10 falls below the threshold.

[0073] From step S10 onward, the same processes as those described in Figure 2 of the first embodiment are performed. After any of steps S50, S60, or S70 is executed, the process shown in the flowchart of Figure 12 is terminated.

[0074] According to the fifth embodiment of the present invention described above, the control circuit 20 further acquires the current value of the power conversion circuit 10 (step S1), and based on the acquired current value, determines the timing for changing the control of the switching element 11 according to the control mode selected in step S30 (step S2). In this way, the load on the switching element 11 when the control mode is changed can be reduced, thereby reducing the probability of deterioration or failure of the switching element 11.

[0075] (Specific examples of switching operations for each control mode) Here, specific examples of the operation of the switching element 11 for each control mode in the first to fifth embodiments described above will be explained below with reference to Figures 13 and 14.

[0076] Figure 13 shows an example of how the duty cycle of the switching element 11 can be changed for each control mode. The drive control unit 24 keeps the duty cycle constant in control mode E, as shown in Figure 13, and changes the duty cycle linearly in response to changes in power demand in control modes D and C. In the example in Figure 13, the slope of the change in the duty cycle in response to changes in power demand is steeper in control mode C than in control mode D. In control modes B and A, the duty cycle is changed quadratically in response to changes in power demand. In the example in Figure 13, the duty cycle changes according to changes in power demand according to a downward-convex curve in control mode B and an upward-convex curve in control mode A.

[0077] Note that the relationship between the change in power demand and the duty cycle in each control mode shown in Figure 13 is just one example and is not limited to this. In each of the first to fifth embodiments, the duty cycle in the operation of the switching element 11 can be changed according to the selected control mode by any method.

[0078] Figure 14 shows an example of how the switching frequency of the switching element 11 can be changed for each control mode. The drive control unit 24, for example as shown in Figure 14, keeps the switching frequency constant in control mode A, and changes the switching frequency linearly in response to changes in power demand in control modes B and C. In the example in Figure 14, the slope of the change in switching frequency in response to changes in power demand is steeper in control mode C than in control mode B. In control modes D and E, the switching frequency is changed quadratically in response to changes in power demand. In the example in Figure 14, the switching frequency changes according to changes in power demand according to an upward-convex curve in control mode D and a downward-convex curve in control mode E.

[0079] Note that the relationship between the change in power demand and the switching frequency in each control mode shown in Figure 14 is just one example and is not limited to this. In each of the first to fifth embodiments, the switching frequency in the operation of the switching element 11 can be changed according to the selected control mode by any method.

[0080] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. Furthermore, any multiple embodiments from the first to fifth embodiments may be arbitrarily combined. [Explanation of Symbols]

[0081] 1, 1A, 1B... Power conversion device, 2... Battery, 3... Battery management device, 4... Inlet, 5... Power supply device, 6... Power load, 7... Power system, 10... Power conversion circuit, 11... Switching element, 12... Transformer, 13... Current sensor, 14... Voltage sensor, 20, 20A, 20B... Control circuit, 21... Memory unit, 22, 22B... Detection unit, 23... Calculation unit, 24... Drive control unit, 25... Judgment unit, 100... Vehicle

Claims

1. A power conversion device installed in a vehicle, A power conversion circuit having multiple switching elements and performing power conversion using the multiple switching elements, The system includes a control circuit that allows selection of one of several control modes and controls the operation of each switching element in the power conversion circuit according to the selected control mode, The power conversion circuit is capable of converting the output power of the battery mounted on the vehicle and outputting it to an external load connected to the vehicle, and also converting the power supplied from an external power source connected to the vehicle and outputting it to the battery. The control circuit acquires the power demand change state of the external load and selects the control mode based on the acquired power demand change state. Power converter.

2. A power conversion device according to claim 1, The control circuit acquires a first change, which is the hourly change in the power demand; a second change, which is the hourly change in the first change; or a third change, which is the hourly change in the second change, as the power demand change state. Power converter.

3. A power conversion device according to claim 1, The control circuit further acquires the magnitude of the power demand of the external load and selects the control mode based on the acquired change in power demand state and magnitude. Power converter.

4. A power conversion device according to claim 1, The control circuit further acquires the charging and supplying state, which is the power input and output state to the power conversion circuit, and selects the control mode based on the acquired power demand change state and the charging and supplying state. Power converter.

5. A power conversion device according to claim 1, The control circuit further acquires the charge state of the battery and selects the control mode based on the acquired change in power demand and the charge state. Power converter.

6. A power conversion device according to claim 1, The control circuit changes the duty cycle in the operation of the switching element according to the selected control mode. Power converter.

7. A power conversion device according to claim 1, The control circuit changes the switching frequency in the operation of the switching element according to the selected control mode. Power converter.

8. A power conversion device according to claim 1, The control circuit further acquires the current value of the power conversion circuit and, based on the acquired current value, determines the timing for changing the control of the switching element according to the selected control mode. Power converter.

9. A power conversion method using a power conversion device capable of converting the output power of a battery mounted on a vehicle into power and outputting it to an external load connected to the vehicle, and converting the power supplied from an external power source connected to the vehicle into power and outputting it to the battery, The state of change in the power demand of the external load is acquired, Based on the acquired power demand change status, one of several control modes is selected. The operation of the multiple switching elements in the power converter is controlled according to the selected control mode. Power conversion method.

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