JP7264023B2 - solar charge controller - Google Patents

Description

The present invention relates to a solar charging control device that controls charging of a battery using power generated by a solar panel.

Patent Literature 1 discloses a solar charging system that temporarily stores power generated by a solar panel in a solar battery, and supplies power from the solar battery to an auxiliary battery or the like when a certain amount of power is stored. . In such a solar charging system, the so-called maximum power point tracking (MPPT) method using the so-called hill-climbing method is used to control the power generated by the solar panel, improving the charging efficiency of the auxiliary battery. I am letting

JP 2015-116067 A

To reduce system costs, it is conceivable to omit the solar battery from the solar charging system. However, if the solar battery is omitted, the maximum power point (MPP) of the solar panel cannot be derived by MPPT-controlling the DCDC converter while storing power in the solar battery.

Therefore, it is conceivable to derive the maximum power point by using the auxiliary battery, which is the charging target, instead of the solar battery. ), etc., new power consumption that was unnecessary when the solar battery was provided is required. Since such additional power consumption causes the auxiliary battery to run out, it is not appropriate to do so regardless of whether power can be generated day or night, whether there is sunlight or not.

So if you omit the solar battery from the system, there is room to consider how to estimate the maximum power point of the solar panel.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a solar charging control device capable of estimating the maximum power point of a solar panel without using a battery to be charged. .

In order to solve the above problems, one aspect of the present invention is a solar charging control device that controls charging of a battery using power generated by a solar panel, and includes a detection unit that detects an output voltage and an output current of the solar panel. , a connection portion that electrically connects the solar panel and the battery, and a control portion that controls the connection portion, the control portion controlling the connection portion to open the output end of the solar panel, and Obtain the open-circuit voltage of the panel from the detector, control the connection to put the output end of the solar panel into a short-circuit state, obtain the short-circuit current of the solar panel from the detector, and calculate the solar panel based on the open-circuit voltage and the short-circuit current. , and if the maximum power point is greater than or equal to the first threshold, the battery is charged with the power generated by the solar panel.

According to the solar charging control device of the present invention, the maximum power point of the solar panel can be estimated without using the battery to be charged.

Schematic configuration diagram of a solar charging system including a solar charging control device according to the present embodiment Solar panel IV characteristic diagram Solar panel PV characteristic chart Configuration example of a solar DCDC converter Processing flowchart of charging control executed by the solar charging control device Diagram for explaining the method of obtaining the open-circuit voltage of the solar panel Diagram for explaining the method of obtaining the short-circuit current of a solar panel Schematic diagram of the solar charging system of Application 1 Schematic configuration diagram of the solar charging system of application example 2

[Embodiment]
An embodiment of the present invention will be described in detail below with reference to the drawings.

<Configuration>
FIG. 1 is a block diagram showing a schematic configuration of a solar charging system including a solar charging control device according to one embodiment of the present invention. A solar charging system 1 illustrated in FIG. 1 includes a solar panel 10 , a solar charging control device 20 according to the present embodiment, a high voltage battery 30 and an auxiliary battery 40 . This solar charging system 1 can be mounted on a vehicle or the like.

The solar panel 10 is a power generation device that generates power by receiving irradiation of sunlight, and is typically a solar cell module that is an assembly of solar cells. The amount of power generated by the solar panel 10 depends on the solar radiation intensity. Electric power generated by the solar panel 10 is output to the solar charging control device 20 . This solar panel 10 can be installed, for example, on the roof of a vehicle.

FIG. 2 exemplifies the IV characteristic representing the power generation capacity of the solar panel 10. As shown in FIG. This IV characteristic shows the correspondence relationship between the voltage V (horizontal axis) and the current I (vertical axis) generated by the solar panel 10 upon receiving light. The open-circuit voltage Voc is the voltage value that appears at the output end of the solar panel 10 when the load is not connected to the output end, that is, when the operating current is set to "0". The short-circuit current Isc is a current value flowing through the output end of the solar panel 10 when the output end is short-circuited, that is, when the operating voltage is set to "0". Also, FIG. 3 illustrates the PV characteristics of the solar panel 10. As shown in FIG. The example of FIG. 3 shows that the solar panel 10 can output maximum power Pmp when the operating voltage is voltage Vmp.

The high voltage battery 30 is a rechargeable secondary battery such as a lithium ion battery or a nickel metal hydride battery. The high-voltage battery 30 is connected to the solar charging control device 20 so as to be charged by the power generated by the solar panel 10 . The high-voltage battery 30 mounted on the vehicle is a so-called drive battery that can supply power necessary for the operation of main equipment (not shown) for driving the vehicle, such as a starter motor and an electric motor. A battery can be exemplified.

Auxiliary battery 40 is a rechargeable secondary battery, such as a lithium-ion battery or a lead-acid battery. The auxiliary battery 40 is connected to the solar charging control device 20 so that it can be charged with the electric power generated by the solar panel 10 . The auxiliary battery 40 mounted on the vehicle is used for auxiliary equipment other than for driving the vehicle, such as lights such as headlamps and interior lights, air conditioners such as heaters and coolers, and devices for automatic driving and advanced driving support. It is a so-called 12V battery capable of supplying electric power necessary for the operation of general equipment (not shown).

The solar charging control device 20 is a connection unit that connects the solar panel 10, the high voltage battery 30, and the auxiliary battery 40, and is capable of supplying power generated by the solar panel 10 to the high voltage battery 30 and the auxiliary battery 40. It is an electronic control unit (ECU) that can This electronic control unit (ECU) typically includes a processor, a memory, an input/output interface, etc. The processor reads out and executes programs stored in the memory to perform various controls. . A solar charging control device 20 according to this embodiment includes a solar DCDC converter 21, a high-voltage DCDC converter 22, an auxiliary DCDC converter 23, a detector 24, and a controller 25 in its configuration.

The solar DCDC converter 21 supplies the electric power generated by the solar panel 10 to the high voltage DCDC converter 22 and the accessory DCDC converter 23 . When supplying power, the solar DCDC converter 21 converts (steps up/steps down) the voltage generated by the solar panel 10, which is the input voltage, into a predetermined voltage based on a duty ratio instructed by the control unit 25, which will be described later. It can be output to the DCDC converter 22 and the accessory DCDC converter 23 . Therefore, the solar DCDC converter 21 can be a buck-boost type DCDC converter capable of PWM (Pulse Width Modulation) control. A large-capacity capacitor 26 for precharging may be connected to the output side of the solar DCDC converter 21 .

FIG. 4 shows a configuration example of a buck-boost solar DCDC converter 21 capable of PWM control. The solar DCDC converter 21 illustrated in FIG. 4 includes a switching element M1 that is a step-down upper arm element, a switching element M2 that is a step-down lower arm element, an inductor L, a switching element M3 that is a step-up lower arm element, and a step-up upper arm element. A rectifying element D4, which is an arm element, is included in the configuration.

The switching elements M1, M2, and M3 are active elements capable of switching ON/OFF operations based on a control signal instructed from the control section 25, and are transistors, for example. For this transistor, for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) can be used. The rectifying element D4 is an active element that allows current to flow in one direction, such as a diode. For this diode, for example, a Schottky Barrier Diode can be used. The inductor L is a passive element that can store magnetic energy by generating a magnetic field by flowing current. This inductor L has a constant current characteristic to try to maintain the current. For the inductor L, for example, a choke coil can be used.

The source of the switching element M1 is connected to (the positive terminal of) the solar panel 10 via the detector 24 . A drain of the switching element M1 is connected to a source of the switching element M2. A drain of the switching element M2 is connected to the ground (negative terminal of the solar panel 10). A drain of the switching element M3 is connected to the ground. The source of switching element M3 is connected to the anode of rectifying element D4. A cathode of the rectifying element D4 is connected to the high voltage DCDC converter 22 and the accessory DCDC converter 23 . Gates of the switching elements M1, M2, and M3 are connected to drive ICs whose gate signals are controlled by the controller 25, respectively. The inductor L is inserted between the connection point between the drain of the switching element M1 and the source of the switching element M2 and the connection point between the anode of the rectifying element D4 and the source of the switching element M3. The solar DCDC converter 21 forms a step-down circuit with the switching element M1, the switching element M2, and the inductor L, and forms a step-up circuit with the inductor L, the switching element M3, and the rectifying element D4.

The high voltage DCDC converter 22 supplies the power output from the solar DCDC converter 21 to the high voltage battery 30 . When supplying power, the high-voltage DCDC converter 22 converts (steps up) the output voltage of the solar DCDC converter 21, which is the input voltage, into a predetermined voltage based on a duty ratio instructed by the control unit 25, which will be described later. 30 can be output. Therefore, the high-voltage DCDC converter 22 can be a step-up DCDC converter capable of PWM control.

Auxiliary DCDC converter 23 supplies power output from solar DCDC converter 21 to auxiliary battery 40 . When supplying power, the auxiliary DCDC converter 23 converts (steps down) the output voltage of the solar DCDC converter 21, which is the input voltage, into a predetermined voltage based on a duty ratio instructed by the control unit 25, which will be described later. It can be output to machine battery 40 . Therefore, the accessory DCDC converter 23 can be a step-down DCDC converter capable of PWM control.

The detector 24 detects the voltage appearing at the output end of the solar panel 10 and the current output from the solar panel 10 to the solar DCDC converter 21 as the power generation status of the solar panel 10 . For example, as shown in FIG. 4, the detection section 24 can be composed of a voltage sensor (V) and a current sensor (A). The voltage value and current value detected by the detection unit 24 are acquired by the control unit 25 .

The control unit 25 is composed of, for example, a microcomputer, and controls the solar DCDC converter 21, the high-voltage DCDC converter 22, and the like based on the voltage value and current value obtained from the detection unit 24, the running state of the vehicle obtained from on-vehicle equipment (not shown), and the like. It controls the operation of the accessory DCDC converter 23 . Each DCDC converter can be controlled, for example, by instructing the duty ratio of a gate signal that turns on/off each switching element.

<Control>
Next, with further reference to FIG. 5, control performed in the present solar charging system 1 will be described. FIG. 5 is a flow chart for explaining the charging control processing procedure executed by the solar charging control device 20 according to the present embodiment.

The charging control shown in FIG. 5 is repeatedly executed while the solar charging system 1 is in operation.

Step S501: The solar charging control device 20 acquires the open-circuit voltage Voc and the short-circuit current Isc appearing at the output terminal of the solar panel 10. FIG. Acquisition of the open-circuit voltage Voc and the short-circuit current Isc can be performed, for example, as follows.

In acquiring the open-circuit voltage Voc, the solar charge control device 20 controls the duty ratio of the gate signals given to the switching elements M1, M2, and M3 of the solar DCDC converter 21 to 0% as shown in FIG. Devices M1, M2, and M3 are all turned off. With this control, the solar panel 10 is separated from the solar DCDC converter 21 and becomes an open state in which current does not flow from the solar panel 10 to the solar DCDC converter 21. Therefore, the open voltage Voc of the solar panel 10 is detected by the voltage sensor ( V) can be detected.

In acquiring the short-circuit current Isc, the solar charging control device 20 controls the duty ratio of the gate signals given to the switching elements M1 and M3 of the solar DCDC converter 21 to 100%, as shown in FIG. M3 is turned on, and the duty ratio of the gate signal applied to the switching element M2 is controlled to 0% to turn off the switching element M2. With this control, the output terminal of the solar panel 10 is short-circuited along the path of switching element M1→inductor L→switching element M3. It can be detected by the sensor (A). If the duty ratio cannot be controlled to 100% due to limitations of the drive IC, a duty ratio (for example, 95%) that allows the switching element to turn on within the limitations may be appropriately set.

After obtaining the open-circuit voltage Voc and the short-circuit current Isc of the solar panel 10, the process proceeds to step S502.

Step S502: The solar charging control device 20 determines whether or not the open-circuit voltage Voc of the solar panel 10 is greater than or equal to the threshold α. This determination is made to determine whether or not the solar panel 10 is in a state in which it is possible to generate enough power to perform efficient charging control, based on the voltage. The threshold α can be set based on the power required by the system, the IV characteristics of the solar panel 10, and the like.

If the open-circuit voltage Voc of the solar panel 10 is greater than or equal to the threshold α (step S502, yes), the process proceeds to step S503, and if the open-circuit voltage Voc of the solar panel 10 is less than the threshold α (step S502, no). , the process proceeds to step S501.

Step S503: The solar charging control device 20 determines whether or not the short-circuit current Isc of the solar panel 10 is greater than or equal to the threshold value β. This determination is made to determine whether or not the solar panel 10 is in a state in which it is possible to generate enough power to perform efficient charging control, based on the current. The threshold β can be set based on the power required by the system, the IV characteristics of the solar panel 10, and the like.

If the short-circuit current Isc of the solar panel 10 is greater than or equal to the threshold β (step S503, yes), the process proceeds to step S504, and if the short-circuit current Isc of the solar panel 10 is less than the threshold β (step S503, no). , the process proceeds to step S501.

Step S504: The solar charging control device 20 estimates the maximum power Pmp of the solar panel 10 based on the open-circuit voltage Voc and short-circuit current Isc of the solar panel 10. Estimation of this maximum power Pmp is performed by calculation based on the following equation (1). The value A is a coefficient determined based on the characteristics, size, etc. of the solar panel 10, and can be set to "0.7" as an example.
Pmp = Voc x Isc x A (1)

Once the maximum power Pmp of the solar panel 10 is estimated, the process proceeds to step S505.

Step S505: The solar charging control device 20 determines whether or not the maximum power Pmp of the solar panel 10 is greater than or equal to the threshold γ (first threshold in claims). This determination is made to determine whether the solar panel 10 is generating enough power to charge the high-voltage battery 30 and the auxiliary battery 40 efficiently. Solar panel 10, which is affected by sunlight, may not be able to stably supply electric power that can efficiently charge high-voltage battery 30 and auxiliary battery 40. FIG. If insufficient power is supplied to the high-voltage battery 30, efficient charging may not be possible. Therefore, the threshold value γ is set to be equal to or higher than a specified value (for example, the minimum value of the guaranteed operation range) determined for efficient charging of the high-voltage battery 30 and the auxiliary battery 40 .

If the maximum power Pmp of the solar panel 10 is greater than or equal to the threshold γ (step S505, yes), the process proceeds to step S506, and if the maximum power Pmp of the solar panel 10 is less than the threshold γ (step S505, no). , the process proceeds to step S501.

Step S506: The solar charging control device 20 determines whether the vehicle is running or not. This determination is made to determine the power supply destination of the power generated by the solar panel 10 . If the vehicle is running (S506, Yes), the process proceeds to step S507, and if the vehicle is not running (S506, No), the process proceeds to step S508.

Step S<b>507 : The solar charging control device 20 controls the solar DCDC converter 21 and the auxiliary DCDC converter 23 to supply the electric power generated by the solar panel 10 to the auxiliary battery 40 to charge the auxiliary battery 40 . After the auxiliary battery 40 is charged, the process returns to step S501.

Step S508: The solar charging control device 20 controls the solar DCDC converter 21 and the high voltage DCDC converter 22 to supply the power generated by the solar panel 10 to the high voltage battery 30 to charge the high voltage battery 30. After the high-voltage battery 30 is charged, the process returns to step S501.

<Application example 1>
The solar charging control device 20 of the above embodiment acquires the open-circuit voltage Voc and the short-circuit current Isc, estimates the maximum power Pmp, and calculates the power supply destination battery (high-voltage battery 30 or auxiliary battery) for the power generated by one solar panel 10. The machine battery 40) was judged. However, the number of solar panels 10 may be two or more.

FIG. 7 shows a schematic configuration of the solar charging system 2 of Application 1. As shown in FIG. The solar charging system 2 includes two solar panels 10a (for example, the front side of the vehicle) and 10b (for example, the rear side of the vehicle). The solar charging control device 27 is provided with a detector 24a and a solar DCDC converter 21a for the solar panel 10a, and is provided with a detector 24b and a solar DCDC converter 21b for the solar panel 10b. The solar charging control device 27 obtains the open-circuit voltage Voc and the short-circuit current Isc for each of the solar panels 10a and 10b, estimates the maximum power Pmp, and determines the power supply destination battery (high-voltage battery 30 or auxiliary battery) based on the results of both. machine battery 40).

<Application example 2>
The solar charging control device 20 of the above embodiment controls the solar DCDC converter 21 to obtain the short circuit current Isc of the solar panel 10, but the short circuit current Isc may be obtained without controlling the solar DCDC converter 21. .

FIG. 8 shows a schematic configuration of the solar charging system 3 of Application 2. As shown in FIG. A switch 29 is provided in the front stage of the solar DCDC converter 21 in the solar charging control device 28 of the solar charging system 3 . By turning on the switch 29 , the solar charging control device 28 can obtain the short-circuit current Isc of the solar panel 10 without controlling the solar DCDC converter 21 . When a plurality of solar panels are used as in Application Example 1 described above, a switch may be provided in front of each solar DCDC converter.

<Action/effect>
As described above, according to the solar charging control device according to one embodiment of the present invention, the solar DCDC converter is controlled to acquire the open-circuit voltage Voc and the short-circuit current Isc of the solar panel, and the acquired open-circuit voltage Voc and Estimate the maximum power Pmp of the solar panel based on the short circuit current Isc. Then, based on the estimated maximum power Pmp of the solar panel, the solar charging control device supplies power generated by the solar panel to the high voltage battery, to the auxiliary battery, and to either the high voltage battery or the auxiliary battery. to selectively control whether or not to supply power.

With this control, it is possible to constantly monitor the power generated by the solar panel, which fluctuates depending on the intensity of sunlight and the shade that occurs while driving. Therefore, it is possible to suppress the loss of the opportunity for power generation by the solar panel, enable efficient charging, and improve the performance of the solar charging system.

Further, according to the solar charging control device according to one embodiment of the present invention, it is sufficient to control only the solar DCDC converter in estimating the maximum power Pmp of the solar panel. This control eliminates the need to consume electric power to activate the components such as the battery monitoring system, other control ECUs, and auxiliary DC/DC converters. can be avoided.

Further, according to the solar charging control device according to one embodiment of the present invention, since the maximum power Pmp is estimated based on the open-circuit voltage Voc and the short-circuit current Isc of the solar panel, the solar panel according to the maximum power point tracking method (MPPT) There is no need to perform scanning processing for scanning the output voltage of Therefore, parts such as resistors and capacitors for absorbing power during scanning processing by the maximum power point tracking method are not required, and the number of system parts can be reduced.

As described above, one embodiment of the present invention has been described. It can be considered as a non-transitory readable storage medium, a solar charging system including a solar charging controller, a vehicle equipped with the solar charging system, and the like.

INDUSTRIAL APPLICABILITY The present invention is applicable to vehicles and the like that charge a battery using power generated by a solar panel.

1, 2, 3 Solar charging system 10, 10a, 10b Solar panel 20, 27, 28 Solar charging control device 29 Switch 21, 21a, 21b Solar DCDC converter 22 High voltage DCDC converter 23 Auxiliary DCDC converter 24, 24a, 24b Detector 25 control unit 26 capacitor 30 high voltage battery 40 auxiliary battery

Claims (1)

A solar charging control device that controls charging of a battery mounted on a vehicle using power generated by a solar panel,
a detection unit that detects the output voltage and output current of the solar panel;
a connecting portion that electrically connects the solar panel and the battery;
A control unit that controls the connection unit,
The control unit
controlling the connection unit to open the output end of the solar panel, and acquiring the open voltage from the detection unit when the open voltage of the solar panel is equal to or higher than a first threshold ;
controlling the connection unit to short-circuit the output end of the solar panel, and acquiring the short-circuit current from the detection unit when the short-circuit current of the solar panel is equal to or greater than a second threshold ;
estimating a maximum power point of the solar panel based on the open-circuit voltage and the short-circuit current when both the open-circuit voltage and the short-circuit current are obtained from the detection unit;
charging an auxiliary battery with electric power generated by the solar panel when the maximum power point is equal to or higher than a third threshold and the vehicle is in a running state;
When the maximum power point is equal to or higher than the third threshold and the vehicle is in a state other than running, the high-voltage battery is charged with power generated by the solar panel;
Solar charging controller.

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