JP6908452B2 - Vehicle solar cell control device, vehicle solar cell control device control method, and vehicle solar cell system - Google Patents

Description

The present disclosure relates to a control device for a solar cell for a vehicle, a control method for a control device for a solar cell for a vehicle, and a solar cell system for a vehicle.

Conventionally, a technique has been proposed in which a solar cell is mounted on a vehicle and the battery of the vehicle is charged by the generated power of the solar cell (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-74733

There was room for improvement in the technology for efficiently using the power generated by the solar cells mounted on the vehicle.

An object of the present disclosure is to provide a control device for a vehicle solar cell, a control method for the control device for a vehicle solar cell, and a vehicle solar cell system capable of efficiently utilizing the generated power of the solar cell mounted on the vehicle. There is.

The vehicle solar cell control device according to the embodiment of the present disclosure controls the output of the solar cell mounted on the vehicle. The vehicle solar cell control device includes a control unit capable of MPPT controlling the output of the solar cell. The control unit determines the necessity of MPPT control for the output of the solar cell based on the amount of solar radiation applied to the solar cell.

The method for controlling the control device for a solar cell for a vehicle according to an embodiment of the present disclosure controls the output of the solar cell mounted on the vehicle. The control method includes a step of determining the necessity of MPPT control with respect to the output of the solar cell based on the amount of solar radiation applied to the solar cell.

The vehicle solar cell system according to the embodiment of the present disclosure includes a solar cell mounted on a vehicle and a control device for controlling the output of the solar cell. The control device includes a control unit capable of MPPT controlling the output of the solar cell. The control unit determines the necessity of MPPT control for the output of the solar cell based on the amount of solar radiation applied to the solar cell.

According to the vehicle solar cell control device, the vehicle solar cell control device control method, and the vehicle solar cell system according to the embodiment of the present disclosure, the generated power of the solar cell mounted on the vehicle is efficiently used. be able to.

It is a figure which shows the schematic structure of the solar cell system for a vehicle which includes the control device which concerns on one Embodiment of this disclosure. It is a schematic diagram which shows the state that the solar cell is installed in the roof part of a vehicle. It is a figure which shows the schematic structure of the DC / DC converter of FIG. It is a figure which shows the example of the IV curve of the solar cell string of FIG. It is a flowchart which shows an example of the operation of the control device which concerns on one Embodiment of this disclosure.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

The vehicle solar cell system 1 shown in FIG. 1 includes a solar cell 10, a control device 20, and a battery 30. In FIG. 1, the solid line connecting each functional block mainly indicates a power line, and the broken line mainly indicates a communication line or a signal line.

The solar cell 10 is a solar cell mounted on a vehicle. The solar cell 10 is installed on the exterior of the vehicle. Since the solar cell 10 receives a large amount of solar radiation, it is installed, for example, on the roof of a vehicle. FIG. 2 shows a schematic view of a state in which the solar cell 10 is installed on the roof portion of the vehicle. The installation location of the solar cell 10 is not limited to the roof portion of the vehicle. The solar cell 10 may be installed in, for example, a bonnet portion, a rear portion, a side portion, or the like. Further, the solar cell 10 may be installed in a plurality of places of the vehicle, for example, a roof portion and a bonnet portion. The solar cell 10 supplies the generated DC power to the control device 20.

The control device 20 controls the output of the solar cell 10 which is a solar cell for a vehicle. The control device 20 converts the DC power supplied from the solar cell 10 into DC power having a predetermined voltage and supplies the DC power to the battery 30.

The battery 30 is charged by the DC power supplied from the control device 20. In the present embodiment, the generated power of the solar cell 10 is used for charging the battery 30, but the destination of the generated power is not limited to this. For example, when the vehicle equipped with the solar cell 10 is a hybrid vehicle or an electric vehicle, the generated power of the solar cell 10 may be supplied to the power motor. Further, the generated power of the solar cell 10 may be supplied to, for example, the electric compressor of the air conditioner of the vehicle.

The solar cell 10 includes a plurality of solar cell strings 11-1 to 11-N connected in parallel to the control device 20. The number N of the solar cell strings 11 may be any number.

The solar cell string 11 includes a plurality of solar cell modules 12 connected in series. The solar cell module 12 is a package in which a plurality of solar cell cells are arranged and packaged.

The control device 20 includes a control unit 21, a storage unit 22, a DC / DC converters 23-1 to 23-N, a battery control unit 24, a voltage sensor 25, and a communication unit 26.

The control unit 21 controls each component of the control device 20. The control unit 21 is configured as, for example, a processor. The control unit 21 may include one or more processors. The processor may include a general-purpose processor that loads a specific program and executes a specific function, and a dedicated processor specialized for a specific process. Dedicated processors may include application-specific ICs (Integrated Circuits). ICs for specific applications are also referred to as ASICs (Application Specific Integrated Circuits). The processor may include a programmable logic device. The programmable logic device is also referred to as a PLD (Programmable Logic Device). The PLD may include an FPGA (Field-Programmable Gate Array). The control unit 21 may be either a SoC (System-on-a-Chip) in which one or a plurality of processors cooperate, or a SiP (System in a Package). The details of the control performed by the control unit 21 will be described later.

The storage unit 22 stores the information acquired from the control unit 21. The storage unit 22 stores a program or the like executed by the control unit 21. The storage unit 22 stores various data such as a calculation result by the control unit 21. The storage unit 22 may function as a work memory of the control unit 21. The storage unit 22 may be composed of, for example, a semiconductor memory, a magnetic memory, or the like. The storage unit 22 may be integrally configured with the control unit 21.

The DC / DC converter 23 is connected to the solar cell string 11 and is supplied with DC power from the solar cell string 11. As shown in FIG. 1, one DC / DC converter 23 is connected to one solar cell string 11.

The control unit 21 controls the output of the solar cell string 11 by using the DC / DC converter 23. When controlling the output of the solar cell string 11 by MPPT (Maximum Power Point Tracking), the control unit 21 turns on the switching of the transistor 232 (see FIG. 3) inside the DC / DC converter 23. When the output of the solar cell string 11 is controlled by a fixed voltage, the control unit 21 turns off the switching of the transistor 232 inside the DC / DC converter 23.

When the control unit 21 MPPT controls the output of the solar cell string 11, the DC / DC converter 23 boosts the voltage of the DC power supplied from the solar cell string 11 to the battery 30 via the battery control unit 24. Supply.

When the control unit 21 controls the output of the solar cell string 11 by a fixed voltage, the DC / DC converter 23 controls the DC power supplied from the solar cell string 11 without performing DC / DC conversion by a switching method. It is supplied to the battery 30 via the unit 24.

FIG. 3 shows a schematic configuration of the DC / DC converter 23. The DC / DC converter 23 includes a choke coil 231, a transistor 232, a diode 233, a capacitor 234, a voltage sensor 235, and a current sensor 236.

The DC / DC converter 23 can operate as a step-up DC / DC converter by means of a choke coil 231, a transistor 232, a diode 233, and a capacitor 234.

The voltage sensor 235 detects the output voltage of the solar cell string 11. The voltage sensor 235 transmits the detected output voltage value to the control unit 21.

The current sensor 236 detects the output current of the solar cell string 11. The current sensor 236 transmits the detected output current value to the control unit 21.

When operating under MPPT control, the DC / DC converter 23 receives a PWM (Pulse Width Modulation) signal from the control unit 21. The PWM signal received from the control unit 21 switches the transistor 232 and operates the DC / DC converter 23 as a step-up DC / DC converter. The control unit 21 modulates the pulse width of the PWM signal based on the output voltage of the solar cell string 11 acquired from the voltage sensor 235 and the output current of the solar cell string 11 acquired from the current sensor 236, and performs MPPT control. conduct.

When the DC / DC converter 23 operates under fixed voltage control, the DC / DC converter 23 receives a signal from the control unit 21 to turn off the transistor 232. In this case, since the transistor 232 does not perform the switching operation, the DC / DC converter 23 does not operate as a step-up DC / DC converter. When operating under fixed voltage control, the DC / DC converter 23 reduces the DC voltage supplied from the solar cell string 11 by the amount of the voltage drop due to the diode 233, and outputs the DC / DC converter 23 to the battery control unit 24.

The MPPT control controls the output of the solar cell string 11 so as to follow the optimum operating point at which the maximum power can be taken out. Therefore, the output of the solar cell string 11 can be maximized by performing MPPT control. However, when the MPPT control is executed, the electric power required for the MPPT control such as the electric power for switching the transistor 232 is generated. Further, in the MPPT control, a loss due to the conversion efficiency of the DC / DC converter 23 being smaller than 1 also occurs.

Considering the power consumption and power loss caused by the MPPT control as described above, it cannot always be said that the MPPT control can efficiently use the generated power of the solar cell 10.

For example, when the solar cell 10 is irradiated with sufficient solar radiation, there is almost no difference in the voltage at the optimum operating point even if there is a slight difference in the amount of solar radiation. For example, in a solar cell module 12 of a certain size, the difference in power at the optimum operating point is about 0.12 [W] between the case where the amount of solar radiation is 1000 [W] and the case where the amount of solar radiation is 800 [W]. In this case, if the switching loss due to MPPT control is larger than 0.12 [W], it is better to perform fixed voltage control at the optimum operating point voltage when the amount of solar radiation is 1000 [W], for example, without MPPT control. , The generated power of the solar cell 10 can be efficiently used.

Therefore, when the amount of solar radiation applied to the solar cell string 11 is equal to or greater than a predetermined threshold value, the control unit 21 controls the output of the solar cell string 11 by a fixed voltage.

The description will be continued with reference to FIG. 1 again.

The battery control unit 24 controls the magnitude of the current drawn by the battery 30 for charging based on the control signal from the control unit 21. When the current drawn by the battery 30 is increased, the output voltage of the DC / DC converter 23 decreases, and when the current drawn by the battery 30 is decreased, the output voltage of the DC / DC converter 23 increases. The control unit 21 controls the battery control unit 24 so that the output voltage of the DC / DC converter 23 becomes a predetermined voltage, and controls the magnitude of the current drawn by the battery 30.

The battery control unit 24 does not have to be included in the control device 20. For example, the battery 30 and the battery control unit 24 may be integrally configured.

The voltage sensor 25 detects the output voltage of the DC / DC converter 23. The voltage sensor 25 transmits the detected output voltage value to the control unit 21.

The communication unit 26 communicates with an ECU (Engine Control Unit) 40 provided inside the vehicle. The communication unit 26 acquires information such as safety information from the ECU 40. The communication unit 26 may communicate with an external server such as a weather server by wireless connection. The communication unit 26 may acquire regional information based on the amount of solar radiation, vehicle position information, regional information of the destination of the vehicle, and the like from an external server such as a weather server.

Subsequently, the operation of the control unit 21 will be described in detail.

The control unit 21 acquires the value of the output voltage of the DC / DC converter 23 from the voltage sensor 25. The control unit 21 controls the battery control unit 24 so that the output voltage of the DC / DC converter 23 becomes a predetermined voltage, and controls the magnitude of the current drawn by the battery 30.

The control unit 21 controls the output of the solar cell string 11 by MPPT control or fixed voltage control. The control unit 21 independently determines whether MPPT control or fixed voltage control is performed for each of the solar cell strings 11-1 to 11-N. For example, the control unit 21 performs fixed voltage control on N-1 solar cell strings 11-1 to 11- (N-1), and MPPT control only on the solar cell strings 11-N, and so on. The output of string 11 can be controlled.

The control unit 21 determines whether or not MPPT control is necessary for the output of the solar cell string 11 based on the amount of solar radiation applied to the solar cell string 11.

When the amount of solar radiation applied to the solar cell string 11 is equal to or greater than a predetermined threshold value, the control unit 21 does not perform MPPT control on the output of the solar cell string 11. In this case, the control unit 21 controls the output of the solar cell string 11 with a fixed voltage. This is because, as described above, when the amount of solar radiation irradiated to the solar cell string 11 is large, it is possible to efficiently use the generated power of the solar cell 10 by controlling the fixed voltage without MPPT control. Because it can be done. The predetermined threshold value may be stored in the storage unit 22 in advance.

The predetermined threshold value may be set as a value at which the power loss due to the deviation from the optimum operating point when the fixed voltage control is applied becomes smaller than the switching loss due to the MPPT control when the amount of solar radiation is equal to or more than the predetermined threshold value. can.

The control unit 21 may change a predetermined threshold value based on the deterioration status, usage history, total irradiation time, and the like of the solar cell 10, the solar cell string 11, and the solar cell module 12. As a result, the control unit 21 can set a predetermined threshold value to an appropriate value according to the output decrease due to the deterioration of the solar cell module 21 and the like.

The control unit 21 MPPT controls the output of the solar cell string 11 when the amount of solar radiation applied to the solar cell string 11 is less than a predetermined threshold value. See FIG. 4, when the amount of solar radiation irradiated to the solar cell string 11 is less than a predetermined threshold value, the power generated by the solar cell 10 may be more efficiently used by performing MPPT control. I will explain.

In the example shown in FIG. 4, the solar cell string 11 includes two solar cell modules 12 connected in series. FIG. 4A is assumed to show the IV curve of the solar cell string 11-1. It is assumed that the solar cell string 11-1 is sufficiently irradiated with sunlight on both of the two solar cell modules 12. FIG. 4B is assumed to show the IV curve of the solar cell string 11-2. The solar cell string 11-2 has a partial shadow, and one of the two solar cell modules 12 is sufficiently exposed to sunlight, but the other one is in the shadow and almost generates electricity. Make it not exist. The state shown in FIG. 4B can occur, for example, when the vehicle is parked in a place where a part of the solar cell string 11-2 is covered with a tree shade.

The IV curve 101 of FIG. 4A shows the IV curve of one solar cell module 12, and the IV curve 102 is the IV curve of the entire two solar cell modules 12 connected in series, that is, the solar cell string. The IV curve of 11-1 is shown. In FIG. 4 _{(a), I SC} denotes a short-circuit _{current, V OC} denotes an open circuit voltage. In the case shown in FIG. 4 (a), the control unit 21 is fixed voltage control the solar cell strings 11-1, DC / DC converter output voltage 23 is fixed voltage _{V 0} in so as the battery controller 24 Is controlled. The fixed voltage V ₀ is assumed to be about 36 [V]. _{Further, the VOC} shown in FIG. 4A is assumed to be about 40 [V].

The IV curve 103 of FIG. 4B shows the IV curve of the entire two solar cell modules 12 connected in series, that is, the IV curve of the solar cell string 11-2. Of the two solar cell modules 12 included in the solar cell strings 11-2, one is in the shadow and therefore hardly generates electricity. Therefore, the IV curve 103 of the solar cell string 11-2 is substantially the same as the IV curve 101 of FIG. 4 (a). _{The VOC} shown in FIG. 4B is assumed to be about 20 [V].

In the example shown in FIG. 4B, the output voltage of the DC / DC converter 23-2 is a fixed voltage V ₀ (36 [V]), which is the open circuit voltage of the solar cell string 11-2. The _{voltage is higher than V OC} (20 [V]). Therefore, when the output of the solar cell string 11-2 is controlled by a fixed voltage, the solar cell string 11-2 cannot supply DC power to the battery control unit 24. As a result, even though one solar cell module 12 that is not covered with a partial shadow can generate power, this generated power is wasted. In such a case, the control unit 21 controls the output of the solar cell string 11-2 by MPPT, so that the generated power of one solar cell module 12 receiving solar radiation can be effectively used. be able to. In the example shown in FIG. 4 (b), the control unit 21 when MPPT control the output of the solar cell string 11-2, the output voltage of the solar cell strings 11-2 becomes _{V M,} the DC / DC converter 23-2 _{The output voltage is V 0} , which is a fixed voltage.

The control unit 21 estimates the amount of solar radiation radiated to the solar cell string 11 based on the value of the output voltage of the solar cell string 11 acquired from the voltage sensor 235 of the DC / DC converter 23. The correspondence between the output voltage of the solar cell string 11 and the amount of solar radiation may be stored in the storage unit 22 as a table in advance. The control unit 21 irradiates the solar cell string 11 based on the value of the output voltage of the solar cell string 11 acquired from the voltage sensor 235 of the DC / DC converter 23 with reference to the table stored in the storage unit 22. The amount of solar radiation may be calculated (estimated).

The control unit 21 may estimate the amount of solar radiation radiated to the solar cell string 11 based on the value of the output current of the solar cell string 11 acquired from the current sensor 236 of the DC / DC converter 23. The correspondence between the output current of the solar cell string 11 and the amount of solar radiation may be stored in the storage unit 22 as a table in advance. The control unit 21 illuminates the solar cell string 11 based on the value of the output current of the solar cell string 11 acquired from the current sensor 236 of the DC / DC converter 23 with reference to the table stored in the storage unit 22. The amount of solar radiation may be calculated (estimated).

The control unit 21 acquires regional information based on the position information of the vehicle, regional information of the destination of the vehicle, and the like from an external server such as a weather server via the communication unit 26, and insolates the solar cell string 11. You may predict the amount.

The solar cell system 1 may include a pyranometer for measuring the amount of solar radiation emitted to the solar cell module 12. The pyranometer may be configured by using at least one solar cell among a plurality of solar cells included in the solar cell module 12, for example. The solar cell module 12 is configured such that at least one solar cell used as a pyranometer among a plurality of solar cells is electrically independent. Specifically, the control unit 21 measures the open circuit voltage value applied to the solar cell used as a pyranometer. The control unit 21 estimates the amount of solar radiation based on the measured open circuit voltage value and the voltage value when the solar radiation is not irradiated. Further, the control unit 21 may measure the current value flowing through a constant load connected to the solar cell used as a pyranometer, and estimate the amount of solar radiation from the measurement result. The solar cell used as a pyranometer does not contribute to the power generation of the solar cell module 12. By using at least one of the plurality of solar cells of the solar cell module 12 as a pyranometer in this way, the pyranometer can be introduced at low cost. The control unit 21 may acquire the amount of solar radiation from the pyranometer.

The control unit 21 does not MPPT control the output of the solar cell string 11 as soon as the amount of solar radiation irradiated to the solar cell string 11 falls below a predetermined threshold value, but the state of being below the predetermined threshold value continues for a predetermined time. In some cases, MPPT control may be performed. As a result, for example, when the vehicle is moving at high speed and the amount of solar radiation temporarily falls below a predetermined threshold due to a partial shadow caused by a shadow of a building or the like, the control unit 21 changes the fixed voltage control to MPPT. It is possible to suppress switching to control.

An example of the operation of the control device 20 according to the embodiment of the present disclosure will be described with reference to the flowchart shown in FIG.

The control unit 21 of the control device 20 acquires the amount of solar radiation applied to the solar cell string 11. For example, the control unit 21 estimates the amount of solar radiation radiated to the solar cell string 11 based on the value of the output voltage of the solar cell string 11 acquired from the voltage sensor 235 of the DC / DC converter 23 (step S101). ..

The control unit 21 determines whether or not the amount of solar radiation applied to the solar cell string 11 is equal to or greater than a predetermined threshold value (step S102).

When the amount of solar radiation irradiated to the solar cell string 11 is equal to or greater than a predetermined threshold value (Yes in step S102), the control unit 21 controls the output of the solar cell string 11 by a fixed voltage (step S103).

When the amount of solar radiation irradiated to the solar cell string 11 is less than a predetermined threshold value (No in step S102), the control unit 21 MPPT controls the output of the solar cell string 11 (step S104).

The control unit 21 independently executes the processes of steps S101 to S104 for each solar cell string 11. Further, the control unit 21 may repeat the processes of steps S101 to S104 at predetermined time intervals.

As described above, according to the present embodiment, the control unit 21 of the control device 20 determines the necessity of MPPT control for the output of the solar cell 10 based on the amount of solar radiation irradiated to the solar cell 10. The control unit 21 controls the output of the solar cell string 11 with a fixed voltage for the solar cell string 11 in which the amount of solar radiation irradiated is large and the generated power can be used more efficiently by controlling the fixed voltage. Further, the control unit 21 MPPT-controls the output of the solar cell string 11 for the solar cell string 11 in which the amount of solar radiation irradiated is small and the generated power can be used more efficiently by performing MPPT control. Therefore, according to the present embodiment, the generated power of the solar cell 10 mounted on the vehicle can be efficiently used.

Although embodiments of the present invention have been described with reference to the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and modifications based on the present disclosure. Therefore, it should be noted that these modifications and modifications are within the scope of the present invention. For example, the functions included in each component and each step can be rearranged so as not to be logically inconsistent, and a plurality of components or steps can be combined or divided into one. Is. Further, although the present invention has been mainly described for the device, the present invention is a method including a step executed by each component of the device, a method executed by a processor included in the device, a program, or a storage medium for recording the program. Can also be realized. It should be understood that these are also included in the scope of the present invention.

1 Vehicle solar cell system 10 Solar cell 11 Solar cell string 12 Solar cell module 20 Control device 21 Control unit 22 Storage unit 23 DC / DC converter 231 Chalk coil 232 Transistor 233 Diode 234 Capacitor 235 Voltage sensor 236 Current sensor 24 Battery control unit 25 Voltage sensor 26 Communication unit 30 Battery 40 ECU

Claims (8)

A control device for vehicle solar cells that controls the output of the solar cells mounted on the vehicle.
A control unit capable of fixed voltage control or MPPT control of the output of the solar cell is provided.
The control unit controlled the solar cell at a first operating point, which is an optimum operating point in the first solar cell, when the amount of solar radiation irradiated to the solar cell is equal to or greater than a predetermined threshold value. The difference in power between the case and the case where the solar cell is controlled at the second operating point, which is the optimum operating point in the second solar cell amount, which is smaller than the first solar cell amount, and the solar cell. Compared with the switching loss when MPPT control is performed, when the difference in power is smaller than the switching loss, a fixed voltage control with respect to the output of the solar cell is performed at the voltage of the first operating point. Control device. The control unit does not perform MPPT control on the output of the solar cell when the difference in power is smaller than the switching loss when the solar cell is MPPT controlled.
The control device for a solar cell for a vehicle according to claim 1. A control device for vehicle solar cells that controls the output of the solar cells mounted on the vehicle.
A control unit capable of fixed voltage control or MPPT control of the output of the solar cell is provided.
The control unit determines the necessity of MPPT control for the output of the solar cell by comparing the amount of solar radiation irradiated to the solar cell with the threshold value.
The threshold value is such that the power loss due to the deviation from the optimum operating point when the output control method of the solar cell is fixed voltage control is larger than the switching loss when the output control method of the solar cell is MPPT control. A control device for a solar cell for a vehicle, which corresponds to the value of the amount of solar radiation irradiated to the solar cell when it becomes smaller. The control unit does not perform MPPT control on the output of the solar cell when the amount of solar radiation irradiated to the solar cell is equal to or greater than the threshold value.
The control device for a solar cell for a vehicle according to claim 3. The control unit controls the output of the solar cell by a fixed voltage when the amount of solar radiation irradiated to the solar cell is equal to or greater than the threshold value.
The control device for a solar cell for a vehicle according to claim 3 or 4. The control unit MPPT controls the output of the solar cell when the amount of solar radiation irradiated to the solar cell is less than the threshold value.
The control device for a solar cell for a vehicle according to claim 3 to 5. The control unit MPPT controls the output of the solar cell when the amount of solar radiation applied to the solar cell is less than the threshold value for a predetermined time.
The control device for a solar cell for a vehicle according to claim 3 to 6. The vehicle solar cell includes a plurality of solar cell strings connected in parallel to the control device.
The control unit determines the necessity of MPPT control for the output of the solar cell string by comparing the amount of solar radiation irradiated to the solar cell string with the threshold value.
The threshold is the power loss due to deviation from the optimum operating point when the control method for the output of the solar cell string is fixed voltage control, and the switching loss when the control method for the output of the solar cell string is MPPT control. Corresponds to the value of the amount of solar radiation applied to the solar cell string when it becomes smaller than
The control device for a solar cell for a vehicle according to claim 3 to 7.

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