AC maximum output power acquisition device

Abstract

To provide an AC maximum output power acquiring apparatus which acquires a maximum power of an AC output annexed to various electric vehicles, an emergency power, etc. and can effectively use the AC power.SOLUTION: An AC fluctuation output control unit 12 for controlling an AC output annexed to an electric vehicle 5 to make it closer to a maximum power point as a fluctuation output controls an AC / DC converter 22 for converting an AC power from the AC output into a DC power to gradually increase the AC power of the AC output to its upper-limit current so that the AC current and / or the AC voltage should be set to a constant value as an operation point of the fluctuation output to make it closer to the AC maximum power point.SELECTED DRAWING: Figure 2

Description

Technical Field

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[0001] The present invention relates to an AC maximum output power acquisition device that acquires the maximum power of AC output attached to an electric vehicle with a built-in battery, an emergency power source, or the like.

Background Art

[0002] In recent years, vehicle-to-home (V2H) in which users utilize in-vehicle batteries of electric vehicles such as electric vehicles (EVs) and hybrid vehicles (HVs) and residential batteries (emergency power sources) during disasters has been increasing. In addition to the grid power, renewable energy power sources such as solar cells are used as these power supplies, and the power is converted by a power conversion device and DC (direct current) power is supplied to the battery.

[0003] For example, since the power generated by a solar cell varies depending on the installation location, weather, etc., as a control for maximizing DC power in order to improve the power generation efficiency, for example, MPPT (Maximum Power Point Tracking) control described in Patent Document 1 is known. In this control, MPPT control is used for the DC output of a DC / DC converter that performs DC power conversion, and the power generation efficiency of the solar cell can be improved.

[0004] By the way, an AC outlet may be attached to an electric vehicle or an emergency power source. With this AC outlet, it is convenient to use large-power electrical appliances such as a coffee maker and a rice cooker outdoors as a load. Also, in a gasoline vehicle, there may be a case where the engine output is converted into electric power and an AC outlet is attached.

[0005] At this time, it is possible to use the electrical appliances as a load even during disasters such as power outages. In such a case, as shown in FIG. 5(A), generally, as the AC output, control is performed to output a fixed current or fixed power that does not cause an overcurrent in the AC current.

[0006] As shown in Figure 5(A), when the conventional method is used in a vehicle with a maximum AC current of 15A and AC100V, the fixed AC current value and the AC current value are the same, the operating power point is constant, and it operates normally. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2022-146593 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, the amount of power stored in the onboard battery of an electric vehicle varies depending on the vehicle model, and the AC output attached to electric vehicles also differs in the maximum AC current that can be output depending on the vehicle model. Similarly, the maximum AC current that can be output varies depending on the output device in the emergency power supply. Furthermore, the optimal AC current to draw from the above AC output also differs depending on the vehicle model.

[0009] Therefore, if the AC current is drawn according to a specific vehicle model, the AC output is obtained from stored power, which may cause the AC voltage to drop unnecessarily, or in some cases, the overcurrent protection may activate and shut down the system. As shown in Figure 5(B), when the conventional method is used for a vehicle with a maximum AC current of less than 15A and AC100V, if the control is performed to output a fixed AC current value of 15A, the AC voltage will drop, and the AC current will become unstable near the overcurrent value, which may cause the AC output to shut down due to overcurrent. If the AC current is further reduced to avoid the above problems, there is also the problem that the available power cannot be drawn sufficiently.

[0010] Furthermore, if the AC cable connecting the AC outlet to the power converter is long, there is a problem in that it is difficult to determine whether the AC current exceeds the upper limit or not due to the voltage drop caused by the resistance of the AC cable length.

[0011] Thus, with conventional technology, when AC output is needed for electric vehicles or emergency power supplies during power outages, it may not be possible to obtain sufficient AC output, making it difficult to make full and effective use of the AC output.

[0012] The present invention aims to solve the above problems and provide an AC maximum output power acquisition device that can acquire the maximum power of the AC output attached to various electric vehicles, emergency power supplies, etc., and ensure the efficient use of AC power. [Means for solving the problem]

[0013] To achieve the above objective, the AC maximum output power acquisition device according to the present invention is provided in a power conversion system comprising an electric vehicle or emergency power supply having a storage battery and a DC / AC inverter, or a gasoline vehicle having at least a DC / AC inverter, a first power conversion device having an AC / DC converter that converts AC power to DC power, and a second power conversion device having a DC / AC inverter that converts DC power to AC power. The first power converter includes an AC variable output control unit that controls the AC output attached to the electric vehicle, emergency power supply, or gasoline vehicle to approach the maximum power point as a variable output. The AC variable output control unit controls the AC / DC converter to gradually increase the AC output current toward its upper limit current, so that the AC current and / or AC voltage become constant values ​​as the operating point of the variable output, and approach the AC maximum power point.

[0014] With this configuration, the AC variable output control unit in the first power converter having an AC / DC converter gradually increases the AC current of the AC output toward its upper limit, controlling the AC current and / or AC voltage to a constant value as the operating point of the variable output, and approaching the AC maximum power point. This prevents a decrease in AC current or AC voltage, and allows the AC output that can be drawn from various electric vehicles, emergency power supplies, etc., to operate at the AC voltage and current that maximizes it. Therefore, even when obtaining AC output from various stored energy sources, the AC output can be fully and effectively utilized.

[0015] Preferably, the AC variable output control unit gradually increases the AC current of the AC output toward its upper limit, and controls the operating point of the variable output to be the point where the AC current stops increasing or where the voltage drop from the starting AC voltage reaches a certain value, thereby reaching near the AC maximum power point. In this case, more effective utilization of the AC output can be achieved.

[0016] Preferably, the AC variable output control unit gradually increases the AC current of the AC output toward its upper limit, and uses the maximum power AC current point and the maximum power AC voltage point as the operating point of the variable output to obtain the maximum AC power point, which is a constant value, by controlling it using a hill-climbing method. In this case, more effective utilization of the AC output can be achieved.

[0017] Preferably, the electric vehicle, emergency power supply, or gasoline vehicle has an AC outlet, to which an AC cable is connected. In this case, even if the AC cable length from the AC outlet becomes long and the AC voltage drops, it is possible to obtain the maximum AC power. [Effects of the Invention]

[0018] In the present invention, the AC fluctuation output control unit in the first power conversion device having an AC / DC converter gradually increases the current of the AC output toward the upper limit current, and controls the AC current and / or the AC voltage to be a constant value as the operating point of the fluctuation output, so as to approach the AC maximum power point. Therefore, it is possible to operate at an AC voltage and current at which the AC output that can be extracted from various electric vehicles, emergency power sources, etc. is maximized. Thus, despite obtaining the AC output from various stored electric powers, it is possible to achieve sufficient effective utilization of the AC output.

Brief Description of the Drawings

[0019] [Figure 1] It is a block diagram showing a power conversion system including an AC maximum output power acquisition device according to an embodiment of the present invention. [Figure 2] It is a characteristic diagram showing an example of the operation of this device. [Figure 3] It is a characteristic diagram showing another example of the operation of this device. [Figure 4] It is a characteristic diagram showing still another example of the operation of this device. [Figure 5] (A) and (B) are characteristic diagrams showing the operation of a conventional device.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described according to the drawings. FIG. 1 is a block diagram showing a power conversion system including an AC maximum output power acquisition device 1 according to an embodiment of the present invention. For example, a first power conversion device 2 and a second power conversion device (power conditioner) 3, which are power conversion devices arranged between the grid power source 4 and the electric vehicle 5 to perform power conversion between the two, are provided.

[0021] The electric vehicle 5 includes an in-vehicle battery 51 that stores DC power, a DC / AC inverter 52 that converts the DC power of the in-vehicle battery 51 into AC power, and an AC outlet 53. An AC cable 54 is connected to the AC outlet 53 and is connected to the first power conversion device 2.

[0022] The first power converter 2 is equipped with an auxiliary input relay 21 and a bidirectional AC / DC converter 22 that converts AC power from the onboard battery 51 to DC power, and is connected to the second power converter (power conditioner) 3. The auxiliary input relay 21 and other components of the first power converter 2 are controlled by the first control unit 10.

[0023] The second power converter (power conditioner) 3 includes a grid connection relay 31 for connecting to the grid power supply 4, a bidirectional inverter (DC / AC inverter) 32 for converting AC power of grid voltage to DC power, and a bus voltage 33. The grid connection relay 31 and other components are controlled by the second control unit 30. A load 6, such as a high-power electrical appliance, is connected to the AC circuit between the grid connection relay 31 and the inverter 32. The AC / DC converter 22 of the first power converter 2 converts AC power supplied from the on-board battery 51 via the AC cable 54 into DC power with a DC voltage corresponding to the bus voltage 33 of the second power converter 3. The first control unit 10 and the second control unit 30 are connected by communication. In the event of a power outage or when the grid connection relay 31 is turned off, the load 6 is driven by the AC output converted by the inverter 32.

[0024] In this invention, an AC maximum output power acquisition device 1 is provided within the first power conversion device 2 of the power conversion device. The AC maximum output power acquisition device 1 includes a current detection unit 13 for detecting AC current, a voltage detection unit 14 for detecting AC voltage, a power calculation unit 15 for calculating AC power, and an AC fluctuation output control unit 12 within the first control unit 11. Effective values ​​are used for AC current and AC voltage, and active power is used for AC power.

[0025] The AC variable output control unit 12 uses an AC / DC converter 22 that changes the AC voltage and current, and gradually increases the AC current of the AC output toward an upper limit current determined by the stored power of various on-board batteries 51, thereby controlling the AC current and / or AC voltage to a constant value as the operating point of the variable output, and bringing it closer to the AC maximum power point.

[0026] Figure 2 shows an example of the operation of the AC variable output control unit 12. In this example, the AC current value is used as a trigger to control the output to reach the vicinity of the AC maximum power point. The AC current of the AC output is gradually increased toward the upper limit current, and point a, where the AC current stops increasing, is set as the operating point of the variable output. From there, the output is controlled to a constant current at that operating point, and power near the AC maximum power point is obtained based on the AC voltage value at this point.

[0027] Figure 3 shows another example of the operation of the AC variable output control unit 12. In this example, the AC voltage value is used as a trigger to control the output to reach the vicinity of the AC maximum power point. The AC current of the AC output is gradually increased toward the upper limit current, the AC voltage value is checked, and the point b where the amount of change due to the voltage drop from the starting AC voltage value before the AC current increase reaches a certain value is controlled to be a constant operating voltage of the variable output, and the power near the AC maximum power point is obtained based on the AC current value at this point.

[0028] Figure 4 shows yet another example of the operation of the AC variable output control unit 12. In this example, the AC current of the AC output is gradually increased toward the upper limit current, and the AC maximum power point where the maximum power AC current point and the maximum power AC voltage point are constant is obtained by controlling it using the hill-climbing method. That is, the AC voltage of the AC output is set to the maximum value, and the AC current of the AC output is gradually increased in constant increments, and the AC voltage of the AC output before and after the change is compared to identify the point c where the AC voltage × AC current equals the maximum AC power, and the AC output that is always constant at the AC voltage and AC current at that point c is obtained.

[0029] Thus, in the present invention, the AC variable output control unit 12 in the first power conversion device 2 having an AC / DC converter 22 gradually increases the AC output current toward the upper limit current determined by the storage capacity of various on-board batteries 51, and controls the AC current and / or AC voltage to a constant value as the operating point of the variable output, approaching the AC maximum power point. This prevents a decrease in AC current and AC voltage, and allows the AC output that can be drawn from various electric vehicles 5 to operate at the AC voltage current that maximizes the AC output. As a result, even though the AC output is obtained from the stored power of various on-board batteries 51, the AC output can be fully and effectively utilized.

[0030] Furthermore, if the AC cable 54 connecting the AC outlet 53 of the electric vehicle 5 to the first power converter 2 becomes longer, even if the AC voltage decreases due to the length of the AC cable 54, it is possible to effectively utilize the AC output by obtaining the maximum AC output power.

[0031] In the above embodiment, a first power converter 2 and a first control unit 10, and a second power converter (power conditioner) 3 and a second control unit 30 are used for power conversion. However, a power converter (power conditioner) and control unit that integrate these components may be used, and the AC maximum output power acquisition device 1 may be provided within this power converter.

[0032] In the above embodiment, grid power is used as the power supply, but renewable energy sources such as solar cells (PV) may also be added as power supplies. In this case, the solar cell and the DC / DC converter that converts this DC power are connected at points D and D in Figure 1. The AC fluctuation output control unit 12 described above is used similarly during nighttime or in the event of a disaster. In this case, MPPT control of the DC output of the solar cell may be performed on the DC / DC converter to maximize the output power of the solar cell, thereby improving the power generation efficiency of the solar cell.

[0033] In the above embodiment, an AC output attached to an electric vehicle is used, but instead, an AC output attached to an electric vehicle such as a hybrid vehicle or a gasoline vehicle equipped with at least a DC / AC inverter may be used. Alternatively, an AC output attached to an emergency power supply may be used instead of an electric vehicle. In this case, a residential battery built into the emergency power supply is used, rather than an on-board battery built into the electric vehicle.

[0034] In addition to solar cells (PV), renewable energy sources may also include fuel cells (FC), wind power (WP), cogeneration, geothermal power, and biomass power.

[0035] The present invention is not limited to the embodiments described above, and various additions, modifications, or deletions are possible without departing from the spirit of the invention. Therefore, such additions and deletions are also included within the scope of the present invention. [Explanation of Symbols]

[0036] 1: AC maximum output power acquisition device 2: First power converter 3: Second power converter (power conditioner) 4: Grid power supply 5: Electric vehicles 10: First Control Unit 12: AC Variable Output Control Unit 22: AC / DC Converter 30: Second control unit 32: Inverter (DC / AC Inverter) 33: Bus voltage 51: Onboard battery 52: DC / AC Inverter 53: AC outlet 54: AC cable

Claims

1. This is provided in a power conversion system comprising an electric vehicle or emergency power supply having a storage battery and a DC / AC inverter, or a gasoline vehicle having at least a DC / AC inverter, a first power conversion device having an AC / DC converter that converts AC power to DC power, and a second power conversion device having a DC / AC inverter that converts DC power to AC power, The first power converter includes an AC variable output control unit that controls the AC output attached to the electric vehicle, emergency power supply, or gasoline vehicle to approach the maximum power point as a variable output. The AC variable output control unit controls the AC / DC converter to gradually increase the AC current of the AC output toward its upper limit, thereby controlling the AC current and / or AC voltage to a constant value as the operating point of the variable output, and bringing it closer to the AC maximum power point, thereby acquiring AC maximum output power.

2. In claim 1, The AC fluctuation output control unit is An AC maximum output power acquisition device that gradually increases the AC current of the AC output toward its upper limit, and controls the operating point of the variable output to be the point where the AC current stops increasing or where the voltage drop from the starting AC voltage reaches a certain value, thereby bringing it near the AC maximum power point.

3. In claim 1, The AC fluctuation output control unit is An AC maximum output power acquisition device that gradually increases the AC current of the AC output toward its upper limit current, and acquires the AC maximum power point where the maximum power AC current point and the maximum power AC voltage point become constant values, using the operating point of the fluctuating output, by controlling it using the hill-climbing method.

4. In any one of claims 1 to 3, The aforementioned electric vehicle, emergency power supply, or gasoline vehicle has an AC outlet, and an AC cable is connected to this AC outlet to obtain the maximum AC output power.

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