Solar charge control device and vehicle

Abstract

To provide a solar charge control device in which power loss in a DCDC converter can be reduced while a backflow of current is prevented.SOLUTION: A solar charge control device for controlling charging a first battery using power generated by a solar panel, includes: a synchronous rectification DCDC converter that is provided between the solar panel and the first battery; and a protective circuit that is inserted between the DCDC converter and the first battery and electrically cuts off the DCDC converter from the first battery if a backflow of current from the first battery to the DCDC converter is detected or if an output voltage from the DCDC converter is below a voltage of the first battery.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a solar charge control device that controls charging of a battery using electric power generated by a solar panel, etc.

Background Art

[0002] Patent Document 1 discloses a device capable of suppressing power loss generated in a rectifying diode in a boost-type DCDC converter. In this device, when the voltage at the anode (input voltage) of the rectifying diode is higher than the voltage at the cathode (output voltage), a switching element provided in parallel with the rectifying diode is operated to allow current to flow, suppressing the power loss of the rectifying diode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to further reduce power loss in a DCDC converter, it is necessary to replace the rectifying diode with a switching element such as a field effect transistor (FET) that can operate with synchronous rectification.

[0005] However, when a synchronous rectification type DCDC converter is used for controlling the generated power of a solar panel where the panel voltage fluctuates greatly, if the voltage on the output side becomes higher than the voltage on the solar panel side during synchronous rectification, an unintended reverse current will occur. Such a reverse current may cause damage to the solar panel or the switching element.

[0006] The present disclosure has been made in view of the above problems, and an object thereof is to provide a solar charge control device or the like that can reduce power loss in a DC-DC converter while preventing reverse flow of an unintended current.

Means for Solving the Problems

[0007] In order to solve the above problems, one aspect of the disclosed technology is a solar charge control device that controls charging of a first battery using electric power generated by a solar panel, the solar charge control device including a synchronous rectification type DC-DC converter provided between the solar panel and the first battery, and a protection circuit inserted between the DC-DC converter and the first battery that electrically disconnects the DC-DC converter and the first battery when a current flowing backward from the first battery to the DC-DC converter is detected or when the output voltage of the DC-DC converter becomes smaller than the voltage of the first battery.

Effects of the Invention

[0008] According to the solar charge control device of the present disclosure or the like, reverse flow of current can be prevented by the protection circuit, and power loss in the DC-DC converter can be reduced by using a synchronous rectification type.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0010] The solar charge control device according to the present disclosure uses an FET for the boost upper arm element of a step-up / down DCDC converter that controls the charging of the electric power generated by a solar panel, and provides a protection circuit that prevents current from flowing backward into the DCDC converter. Thereby, power loss in the DCDC converter can be reduced. Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0011] <Embodiment> [Basic Configuration] FIG. 1 is a block diagram showing a schematic configuration of a solar charge control device 1 according to an embodiment of the present disclosure. The solar charge control device 1 illustrated in FIG. 1 includes a solar panel 10, a battery 20, a DCDC converter 30, a DDC control unit 40, a buck driver 50, a boost driver 60, and a protection circuit 70. This solar charge control device 1 can be mounted on a vehicle or the like.

[0012] The solar panel 10 is a power generation device that generates power when irradiated with sunlight, and is typically a solar cell module that is an aggregate of solar cells. This solar panel 10 can be installed, for example, on the roof of a vehicle. The solar panel 10 is connected to the DCDC converter 30, and the power generated by the solar panel 10 is output to the DCDC converter 30.

[0013] The battery 20 is a secondary battery configured to be chargeable and dischargeable, such as a lithium-ion battery. This battery 20 is connected to the DCDC converter 30 so as to be chargeable by the power generated by the solar panel 10.

[0014] The DCDC converter 30 is a step-up / step-down type DCDC converter for supplying the power generated by the solar panel 10 to the battery 20. When supplying power, the DCDC converter 30 can convert (step up / step down) the panel voltage VSP, which is the generated voltage of the solar panel 10 and the input voltage, to a predetermined voltage VSPof, and output it to the battery 20 via the protection circuit 70. This DCDC converter 30 is of a synchronous rectification type that includes a switching element M1 which is an upper arm element for step-down, a switching element M2 which is a lower arm element for step-down, a switching element M3 which is an upper arm element for step-up, a switching element M4 which is a lower arm element for step-up, and a coil L in its configuration.

[0015] The switching elements M1, M2, M3, and M4 are active elements that can be controlled to switch ON / OFF by the step-down driver 50 and the step-up driver 60 under the instruction of the DDC control unit 40, and are, for example, transistors. These switching elements M1, M2, M3, and M4 can conduct current when under ON control (applying an ON voltage to the gate). For the transistors, for example, metal oxide semiconductor field effect transistors (MOSFETs: Metal Oxide Semiconductor Field Effect Transistors) can be used. The coil L is a passive element that can generate a magnetic field by the flowing current and store magnetic energy. For this coil L, for example, a choke coil having a constant current characteristic for maintaining the current can be used.

[0016] The source of the switching element M1 is connected to the solar panel 10 (positive output terminal). The drain of the switching element M1 is connected to the source of the switching element M2. The drain of the switching element M2 is grounded (ground potential). The source of the switching element M3 is connected to the battery 20 via the protection circuit 70. The drain of the switching element M3 is connected to the source of the switching element M4. The drain of the switching element M4 is grounded. The gates of the switching elements M1 and M2 are respectively connected to the buck driver 50. The gates of the switching elements M3 and M4 are respectively connected to the boost driver 60. The coil L is inserted between the connection point of the drain of the switching element M1 and the source of the switching element M2 and the connection point of the drain of the switching element M3 and the source of the switching element M4.

[0017] The DCDC converter 30 forms a buck circuit with the switching element M1, the switching element M2, and the coil L, and can step down the output voltage from the solar panel 10 and output it to the battery 20. Also, the DCDC converter 30 forms a boost circuit with the coil L, the switching element M3, and the switching element M4, and can step up the output voltage from the solar panel 10 and output it to the battery 20.

[0018] The DDC control unit 40 is a configuration for controlling the power transfer between the solar panel 10 and the battery 20 by controlling the operation (boost / buck) of the DCDC converter 30. This DDC control unit 40 instructs the buck driver 50 and the boost driver 60 on the duty ratio (ON ratio of the switching element) of the signal applied to the gates of the switching elements M1, M2, M3, and M4 so that the output voltage of the DCDC converter 30 becomes a predetermined target voltage. The DDC control unit 40 is composed of a processor such as a CPU, for example.

[0019] The buck driver 50 and the boost driver 60 control the gate voltages of the switching elements M1, M2, M3, and M4 according to instructions from the DDC control unit 40, and independently control the on / off operations of the respective switching elements. Thereby, the panel voltage VSP of the solar panel 10 is controlled.

[0020] The protection circuit 70 is inserted between the DCDC converter 30 and the battery 20, and is configured to electrically disconnect the DCDC converter 30 and the battery 20 when detecting a current flowing backward from the battery 20 to the DCDC converter 30. For example, the following configuration is used for this protection circuit 70.

[0021] As a specific configuration applicable to this protection circuit 70, the ideal diode IC71 shown in Fig. 2A can be exemplified. This ideal diode IC71 realizes ideal diode characteristics with a forward voltage of zero and current flowing only in one direction by an integrated circuit (IC). Therefore, the ideal diode IC71 can greatly reduce power loss compared with discrete rectifier diodes. Since the output voltage VSPof of the DCDC converter 30 is suppressed from transient fluctuations by the smoothing capacitor C, the ideal diode IC71 can follow and control even when current flows backward to the DCDC converter 30 or when it becomes smaller than the voltage VSPo of the battery 20.

[0022] Also, as another specific configuration applicable to the protection circuit 70, an electric circuit having a resistor 72, an operational amplifier 73, a driver 74, and a switching element (FET) 75 shown in Fig. 2B can be exemplified. In this electric circuit, the current flowing backward through the switching element 75 is detected by the resistor 72 and the operational amplifier 73 (detection unit), and when the backward flow is detected, the driving (on operation) of the switching element 75 by the driver 74 is stopped.

[0023] [Application Example of Configuration] FIG. 3 is a block diagram showing a schematic configuration of an applied solar charge control device 2 according to an embodiment of the present disclosure. The solar charge control device 2 illustrated in FIG. 3 has a configuration in which the solar panel 10 of the solar charge control device 1 illustrated in FIG. 1 above is replaced with a second battery 110.

[0024] As shown in FIG. 3, in a system in which the power source for charging the battery (first battery) 20 is not the solar panel 10 but another battery power source such as the second battery 110, when it is desired to prevent the reverse flow of current from the battery (first battery) 20 to the second battery 110, the solar charge control device 2 of the present disclosure is useful.

[0025] FIG. 4 is a block diagram showing a schematic configuration of another applied solar charge control device 3 according to an embodiment of the present disclosure. The solar charge control device 3 illustrated in FIG. 4 has a configuration in which the boost - buck type DCDC converter 30 of the solar charge control device 1 illustrated in FIG. 1 above is replaced with a buck - type DCDC converter 230, and the DDC control unit 40 that controls boost - buck is replaced with a DDC control unit 240 that controls buck only.

[0026] As shown in FIG. 4, in a configuration using a buck - type DCDC converter 230 that operates only when the panel voltage VSP of the solar panel 10 is higher than the voltage VSPo of the battery 20, in other configurations of DCDC converters, it is possible to prevent the reverse flow of current from the battery 20 to the solar panel 10. Of course, the solar panel 10 in FIG. 4 may be replaced with the second battery 110 in FIG. 3.

[0027] <Effect> According to the solar charge control device according to the embodiment of the present disclosure described above, in a configuration in which the boost upper - arm element of the DCDC converter is a switching element that operates by synchronous rectification, when a current that reverses the DCDC converter is generated due to fluctuations in the input - output voltage value, the path is interrupted by a protection circuit provided on the output side of the DCDC converter (boost upper - arm element).

[0028] With this configuration, the rectifier diode with high power loss can be removed, so that the conversion efficiency of the DCDC converter can be improved. In addition, since the reverse current of the DCDC converter can be prevented, there is no need to worry about the destruction of the panel and elements in the synchronous rectification method, and it can be applied to a solar charging system using a solar panel as a power source without any problems.

[0029] As described above, one embodiment of the disclosed technology has been described. However, the present disclosure can be understood not only as a solar charge control device, but also as a method performed by the solar charge control device, a program of the method, a computer-readable non-transitory storage medium storing the program, a vehicle equipped with the solar charge control device, and the like.

Industrial Applicability

[0030] The solar charge control device of the present disclosure can be used in a solar charging system that charges the generated power of a solar panel to a battery.

Description of Reference Numerals

[0031] 1, 2, 3 Solar charge control device 10 Solar panel 20 Battery (first battery) 30, 230 DCDC converter 40, 240 DDC control unit 50 Step-down driver 60 Boost driver 70 Protection circuit 71 Ideal diode IC 72 Resistor 73 Operational amplifier 74 Driver 75 Switching element 110 Second battery C Capacitor L Coil M1~M4 Switching element (FET)

Claims

1. A solar charge control device that controls charging of a first battery using electric power generated by a solar panel, a synchronous rectification type DC-DC converter provided between the solar panel and the first battery, a protection circuit inserted between the DC-DC converter and the first battery, which electrically disconnects the DC-DC converter and the first battery when a current flowing backward from the first battery to the DC-DC converter is detected or when the output voltage of the DC-DC converter becomes smaller than the voltage of the first battery. A solar charge control device comprising:

2. A solar charge control device that controls charging of a first battery using electric power of a second battery, a synchronous rectification type DC-DC converter provided between the first battery and the second battery, a protection circuit inserted between the DC-DC converter and the first battery, which electrically disconnects the DC-DC converter and the first battery when a current flowing backward from the first battery to the DC-DC converter is detected or when the output voltage of the DC-DC converter becomes smaller than the voltage of the first battery. A solar charge control device comprising:

3. The DC-DC converter is a step-up / step-down type DC-DC converter, The protection circuit is connected to the output of the upper arm element for boosting, and the solar charge control device according to claim 1 or 2.

4. The DC-DC converter is a step-down type DC-DC converter, The protection circuit is connected to the output of the coil, and the solar charge control device according to claim 1 or 2.

5. The protection circuit is an ideal diode IC, and the solar charge control device according to claim 1 or 2.

6. The protection circuit is a switching element that switches the conduction / non-conduction state between the DC-DC converter and the first battery, a detection unit that detects the backward current, a control unit that stops driving the switching element when the backward current is detected by the detection unit, and the solar charge control device according to claim 1 or 2.

7. A vehicle equipped with the solar charge control device according to any one of claims 1 to 6.

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