Solar charging control device and vehicle

Abstract

The invention provides a solar charging control device and a vehicle. A solar charging control device for controlling charging of a first battery using power emitted by a solar panel, the solar charging control device being provided with: a synchronous rectification type DC-DC converter provided between the solar panel and the first battery; and a protection circuit that is inserted between the DCDC converter and the first battery, and electrically blocks the DCDC converter and the first battery when a current flowing back from the first battery to the DCDC converter is detected or when an output voltage of the DCDC converter is lower than a voltage of the first battery.

Description

Technical Field

[0001] The present disclosure relates to a solar charging control device that controls charging of a battery using electric power generated by a solar panel, and the like. Background Art

[0002] In Japanese Unexamined Patent Application Publication No. 2014-003728, a device that can suppress power loss generated by a rectifying diode in a boost-type DC-DC converter is disclosed. In this device, when the voltage (input voltage) at the anode of the rectifying diode is higher than the voltage (output voltage) at the cathode, a switching element arranged in parallel with the rectifying diode is operated to allow current to flow, thereby suppressing the power loss of the rectifying diode.

[0003] In order to further reduce power loss in the DC-DC converter, it is necessary to replace the rectifying diode with a switching element such as a field effect transistor (FET) that can operate by synchronous rectification.

[0004] However, when a synchronous rectification type DC-DC converter is used for controlling the generated power of a solar panel whose panel voltage is likely to vary greatly, if the voltage on the output side is higher than the voltage on the solar panel side during synchronous rectification, an unwanted current reflux will occur. Such a current reflux may cause damage to the solar panel, switching element, etc. Summary of the Invention

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a solar charging control device and the like that can prevent an unwanted current reflux and reduce power loss in a DC-DC converter.

[0006] To solve the above problems, one aspect of the technology of the present disclosure is a solar charging control device that controls charging of a first battery using electric power generated by a solar panel, wherein the solar charging control device includes: 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, which electrically disconnects the DC-DC converter and the first battery when a current refluxing from the first battery to the DC-DC converter is detected, or when the output voltage of the DC-DC converter is less than the voltage of the first battery.

[0007] According to the solar charging control device and the like of the present disclosure, it is possible to prevent current reflux through the protection circuit and reduce power loss in the DC-DC converter by using synchronous rectification. Brief Description of the Drawings

[0008] The features, advantages, and technical and industrial significance of the embodiments of the present invention will be described below with reference to the accompanying drawings, and the same reference numerals denote the same elements, where,

[0009] Figure 1 is a schematic structural diagram of a solar charging control device according to one embodiment of the present disclosure.

[0010] Figure 2A is Figure 1 a specific structural example of the protection circuit shown.

[0011] Figure 2B is Figure 1 another specific structural example of the protection circuit shown.

[0012] Figure 3 is an application example of a solar charging control device according to one embodiment of the present disclosure.

[0013] Figure 4 is another application example of a solar charging control device according to one embodiment of the present disclosure. Detailed Embodiments

[0014] In the solar charging control device of the present disclosure, an FET is used as a boosting upper arm element of a buck-boost type DCDC converter for controlling the charging of the generated power of a solar panel, and a protection circuit for preventing current from flowing back to the DCDC converter is provided. Thereby, power loss in the DCDC converter can be reduced.

[0015] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0016] Embodiment

[0017] Basic Structure

[0018] Figure 1 is a block diagram showing a schematic structure of a solar charging control device 1 according to one embodiment of the present disclosure. In Figure 1 The illustrated solar charging control device 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. The solar charging control device 1 can be mounted on a vehicle or the like.

[0019] 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 cell units. The solar panel 10 can be provided, 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.

[0020] The battery 20 is a secondary battery such as a lithium-ion battery that can be charged and discharged. The battery 20 is connected to the DCDC converter 30 in such a way that it can be charged by the electric power generated by the solar panel 10.

[0021] The DCDC converter 30 is a step-up / step-down type DCDC converter for supplying the electric power emitted by the solar panel 10 to the battery 20. When supplying electric power, the DCDC converter 30 can convert (step up / step down) the generated voltage of the solar panel 10, i.e., the panel voltage VSP, which is the input voltage, into a specified voltage VSPof, and output it to the battery 20 via the protection circuit 70. The DCDC converter 30 is a synchronous rectification type that includes, in its structure, a switching element M1 as an upper-arm element for step-down, a switching element M2 as a lower-arm element for step-down, a switching element M3 as an upper-arm element for step-up, a switching element M4 as a lower-arm element for step-up, and a coil L.

[0022] The switching elements M1, M2, M3, and M4 are active elements that can be switched and controlled based on the instructions of the DDC control unit 40 by the conduction (ON) / disconnection (OFF) of the step-down driver 50 and the step-up driver 60. For example, they are transistors. The switching elements M1, M2, M3, and M4 can allow current to flow when under conduction control (applying a conduction voltage to the gate). For transistors, for example, metal-oxide-semiconductor field effect transistors (MOSFET: Metal Oxide Semiconductor Field Effect Transistor) can be used. The coil L is a passive element that can store magnetic energy by generating a magnetic field through the flowing current. For this coil L, for example, a choke coil with a constant current characteristic of wanting to maintain current can be used.

[0023] 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 step-down driver 50. The gates of the switching elements M3 and M4 are respectively connected to the step-up 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.

[0024] The DCDC converter 30 can form a buck circuit with the switching element M1, the switching element M2, and the coil L to step down the output voltage from the solar panel 10 and output it to the battery 20. Additionally, the DCDC converter 30 can form a boost circuit with the coil L, the switching element M3, and the switching element M4 to step up the output voltage from the solar panel 10 and output it to the battery 20.

[0025] The DDC control unit 40 is a structure for controlling the power transfer between the solar panel 10 and the battery 20 by controlling the operation (boosting / buckling) of the DCDC converter 30. This DDC control unit 40 instructs the duty ratio (the conduction ratio of the switching element) of the signals applied to the gates of the switching elements M1, M2, M3, and M4 to the buck driver 50 and the boost driver 60 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.

[0026] The buck driver 50 and the boost driver 60 control the gate voltages of the switching elements M1, M2, M3, and M4 according to the instructions from the DDC control unit 40, thereby independently controlling the on / off operations of the respective switching elements. Thereby, the panel voltage VSP of the solar panel 10 is controlled.

[0027] The protection circuit 70 is formed in the following structure: it is inserted between the DCDC converter 30 and the battery 20 and is used to electrically isolate the DCDC converter 30 and the battery 20 when a current flowing back from the battery 20 to the DCDC converter 30 is detected. For this protection circuit 70, the following structures can be used, for example.

[0028] As a specific structure that can be applied to this protection circuit 70, Figure 2A the ideal diode IC71 shown can be exemplified. This ideal diode IC71 is a diode that realizes the ideal diode characteristics of having a forward voltage of zero and only flowing current in one direction through an integrated circuit (IC). Therefore, compared with discrete rectifier diodes, the ideal diode IC71 can greatly reduce power loss. Since the voltage VSPof, which is the output voltage of the DCDC converter 30, can be suppressed from having transient fluctuations by the smoothing capacitor C, the ideal diode IC71 can also be controlled accordingly even when current flows back to the DCDC converter 30 or when it is smaller than the voltage VSPo of the battery 20.

[0029] Additionally, as another specific structure that can be applied to the protection circuit 70, Figure 2BThe electrical circuit shown includes a resistor 72, an operational amplifier 73, a driver 74, and a switching element (FET) 75. In this electrical circuit, the current flowing back through the switching element 75 is detected by the resistor 72 and the operational amplifier 73 (detection unit), and when a reverse current is detected, the driving (turn-on operation) of the switching element 75 by the driver 74 is stopped.

[0030] Application example of the structure

[0031] Figure 3 It is a block diagram showing a schematic structure of a solar charge control device 2 related to one embodiment of the present disclosure. In this Figure 3 The solar charge control device 2 illustrated in the example is a structure in which the solar panel 10 of the solar charge control device 1 illustrated in the above Figure 1 is replaced with a second battery 110.

[0032] As shown in this Figure 3 , even in a system where the power source for charging the battery (first battery) 20 is not a solar panel 10 but another battery power source such as the second battery 110, the solar charge control device 2 of the present disclosure is useful when it is desired to prevent current from flowing back from the battery (first battery) 20 to the second battery 110.

[0033] In addition, Figure 4 It is a block diagram showing a schematic structure of a solar charge control device 3 related to another application of the present disclosure. In this Figure 4 The solar charge control device 3 illustrated in the example is a structure in which the buck-boost type DCDC converter 30 of the solar charge control device 1 illustrated in the above Figure 1 is replaced with a buck type DCDC converter 230, and the DDC control unit 40 for controlling buck-boost is replaced with a DDC control unit 240 that only controls buck.

[0034] As shown in this Figure 4 , by using a structure of another DCDC converter such as 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, it is also possible to prevent current from flowing back from the battery 20 to the solar panel 10. Of course, the Figure 4 solar panel 10 can be replaced with Figure 3 the second battery 110.

[0035] Effect

[0036] According to the solar charging control device related to one embodiment of the present disclosure described above, in a structure where the boost upper arm element of the DCDC converter is a switching element that operates through synchronous rectification, when a current flowing back in the DCDC converter is generated due to fluctuations in the input-output voltage values, the path is blocked by a protection circuit provided on the output side of the DCDC converter (boost upper arm element).

[0037] With this structure, since the rectifier diode with large power loss can be removed, the conversion efficiency of the DCDC converter can be improved. In addition, since the backflow current of the DCDC converter can be prevented, there is no need to worry about damage to the panel and components in the synchronous rectification method, and it can also be applied without problems in a solar charging system that uses a solar panel as a power source.

[0038] As described above, one embodiment of the present disclosure technology has been described, but the present disclosure can be understood not only as a solar charging control device, but also as a method performed by the solar charging control device, a program of this method, a non-temporary storage medium readable by a computer storing this program, a vehicle equipped with a solar charging control device, and the like.

[0039] The solar charging control device of the present disclosure can be used in a solar charging system that charges the generated power of a solar panel in a battery, etc.

Claims

1. A solar charging control device for controlling charging of a first battery using power generated by a solar panel, wherein: The solar charging control device comprises: a DCDC converter, the DCDC converter being a synchronous rectification type and disposed between the solar panel and the first battery; and A protection circuit is inserted between the DCDC converter and the first battery, and electrically isolates the DCDC converter from the first battery when a current flowing back from the first battery to the DCDC converter is detected or when an output voltage of the DCDC converter is lower than a voltage of the first battery.

2. A solar charging control device for controlling charging of a first battery using power from a second battery, wherein: The solar charging control device comprises: a DCDC converter, the DCDC converter being a synchronous rectification type and being disposed between the first battery and the second battery; and A protection circuit is inserted between the DCDC converter and the first battery, and electrically isolates the DCDC converter from the first battery when a current flowing back from the first battery to the DCDC converter is detected or when an output voltage of the DCDC converter is lower than a voltage of the first battery.

3. The solar charging control device according to claim 1 or 2, wherein: The DCDC converter is a buck-boost DCDC converter. The protection circuit is connected to the output of the boost upper arm element.

4. The solar charging control device according to claim 1 or 2, wherein: The DCDC converter is a step-down DCDC converter. The protection circuit is connected to the output of the coil.

5. The solar charging control device according to claim 1 or 2, wherein: The protection circuit is an ideal diode IC.

6. The solar charging control device according to claim 1 or 2, wherein: The protection circuit comprises: a switch element for switching a conduction state or a disconnection state between the DCDC converter and the first battery; a detection unit, the detection unit detecting the reflux current; as well as The control unit stops driving the switching element when the detection unit detects the return current.

7. A vehicle, wherein: The solar charging control device according to any one of claims 1 to 6 is mounted thereon.

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