Solar charging system, method, and vehicle

Abstract

A solar charging system, a method, and a vehicle are disclosed. The solar charging system includes a solar panel, a first power conversion device configured to receive power generated by the solar panel and detect or derive input power and output power of the first power conversion device, and a second power conversion device configured to receive power output from the first power conversion device and detect or derive input power and output power of the second power conversion device.

Description

Technical Field

[0001] This disclosure relates to solar charging systems, methods, and vehicles. Background Technology

[0002] Japanese Unexamined Patent Application Publication No. 2021-087291 (JP 2021-087291 A) describes a solar charging system that includes two solar panels, two solar DC-DC converters respectively disposed for the solar panels, a high-voltage DC-DC converter that provides power from the output of the solar DC-DC converters to a high-voltage battery, and an auxiliary DC-DC converter that provides power from the output of the solar DC-DC converters to an auxiliary battery. Summary of the Invention

[0003] In a system comprising multiple DC-DC converters as described in JP 2021-087291 A, it is desirable to be able to identify the DC-DC converter associated with the location of the anomaly when an anomaly occurs in the system.

[0004] This disclosure provides a solar charging system, method, and vehicle that can identify a faulty DC-DC converter when an anomaly occurs in the system.

[0005] One aspect of this disclosure provides a solar charging system. The solar charging system includes a solar panel, a first power conversion device, and a second power conversion device. The first power conversion device is configured to receive power generated by the solar panel and to detect or export input and output power. The second power conversion device is configured to receive power exported from the first power conversion device and to detect or export input and output power.

[0006] Another aspect of this disclosure provides a method performed by a solar charging system. The solar charging system includes: a solar panel; a first DC-DC converter configured to receive power generated by the solar panel; a second DC-DC converter configured to detect or export input and output power from the second DC-DC converter and output power input from the first DC-DC converter to a first battery; and a third DC-DC converter configured to detect or export output power from the third DC-DC converter and output power input from the first DC-DC converter to a second battery. The method includes identifying the location of the anomaly based on the input and output power of the first DC-DC converter, the input and output power of the second DC-DC converter, and the input and output power of the third DC-DC converter when an anomaly occurs in the solar charging system.

[0007] Another aspect of this disclosure provides a vehicle that includes a solar charging system according to the above-described approach.

[0008] Using the solar charging system, method, and vehicle according to the present disclosure, the location of the anomaly in the power conversion device (DC-DC converter) can be identified when an anomaly exists in the system. Attached Figure Description

[0009] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, wherein like numerals refer to like elements, and wherein:

[0010] Figure 1 This is a schematic configuration diagram of a solar charging system according to an embodiment;

[0011] Figure 2 This is an example of a circuit that assists a DDC (direct-to-direct-current converter);

[0012] Figure 3 This is a flowchart of the abnormal control process (first example) performed by the solar charging system;

[0013] Figure 4 This is a flowchart of the auxiliary DDC fault protection process performed by the solar charging system; and

[0014] Figure 5 This is a flowchart of the abnormal control process (second example) performed by the solar charging system. Detailed Implementation

[0015] The solar charging system according to this disclosure improves system efficiency and reliability by accurately identifying the location of the anomaly based on, for example, the balance between the input and output power of each DC-DC converter when an anomaly occurs in the system. Embodiments of this disclosure will be described in detail below with reference to the accompanying drawings.

[0016] Example

[0017] Configuration

[0018] Figure 1 This is a block diagram illustrating a schematic configuration of a solar charging system according to an embodiment of the present disclosure. Figure 1 The solar charging system 1 shown includes two solar panels 11 and 12, two solar DC-DC converters 21 and 22, a high-voltage DC-DC converter 30, an auxiliary DC-DC converter 40, a high-voltage battery 50, an auxiliary battery 60, a capacitor 70, and a processing unit 100. The solar charging system 1 can be installed on vehicles, etc.

[0019] Each of the solar panels 11 and 12 is a power generation device that generates electricity when exposed to sunlight, and is typically a solar cell module consisting of an assembly of solar cells. Solar panels 11 and 12 can be mounted, for example, on the roof of a vehicle. Solar panel 11 is connected to a solar power distribution unit (DDC) 21 (described later), and the electricity generated by solar panel 11 is output to solar power distribution unit 21. Solar panel 12 is connected to a solar power distribution unit (DDC) 22 (described later), and the electricity generated by solar panel 12 is output to solar power distribution unit 22. Solar panels 11 and 12 may have the same performance, capacity, size, shape, etc., or may be partially or completely different.

[0020] Solar DC-DC converters 21 and 22 are respectively configured to correspond to solar panels 11 and 12. Each of the solar DC-DC converters 21 and 22 is a first DC-DC converter that supplies power generated by a corresponding solar panel 11 or 12 to the high-voltage DC-DC converter 30 and the auxiliary DC-DC converter 40. When solar DC-DC converter 21 provides power, it can convert (boost or buck) the generated voltage of the solar panel 11 as the input voltage to a predetermined voltage and output this voltage to the high-voltage DC-DC converter 30 and the auxiliary DC-DC converter 40. When solar DC-DC converter 22 provides power, it can convert (boost or buck) the generated voltage of the solar panel 12 as the input voltage to a predetermined voltage and output this voltage to the high-voltage DC-DC converter 30 and the auxiliary DC-DC converter 40. Thus, each of the solar DC-DC converters 21 and 22 serves as a first power conversion device capable of converting input power from a corresponding solar panel 11 or 12 into desired output power. Solar DDC 21 includes components (not shown) capable of detecting or extracting power from the input side [A] to which solar panel 11 is connected, and power from the output side [B] to which high-voltage DDC 30 and auxiliary DDC 40 are connected. Solar DDC 22 includes components (not shown) capable of detecting or extracting power from the input side [C] to which solar panel 12 is connected, and power from the output side [D] to which high-voltage DDC 30 and auxiliary DDC 40 are connected. For example, the input and output power of each of solar DDCs 21 and 22 can be obtained by detecting the input and output power of each using a power sensor (not shown), or by extracting the input and output power from the input and output voltages and currents of each of solar DDCs 21 and 22 detected using a voltage sensor (not shown) and a current sensor (not shown). The configuration and performance of solar DDCs 21 and 22 can be the same or can vary depending on solar panels 11 and 12.

[0021] In the solar panels 11 and 12 and the solar power distribution units 21 and 22, solar panel 11 and solar power distribution unit 21 form one panel power generation control unit, and solar panel 12 and solar power distribution unit 22 form another panel power generation control unit. In the solar charging system 1 of this embodiment, a configuration with two panel power generation control units connected in parallel is described as an example. The solar charging system can be configured to have only one panel power generation control unit or three or more panel power generation control units.

[0022] The high-voltage DDC 30 is a DC-DC converter (second DC-DC converter) that supplies power from the solar DDCs 21 and 22 to the high-voltage battery 50. When the high-voltage DDC 30 supplies power, it is capable of converting (boosting) the output voltage of the solar DDCs 21 and 22, which are input voltages, to a predetermined voltage and outputting that voltage to the high-voltage battery 50. The high-voltage DDC 30 includes components (not shown) capable of detecting or extracting power from the input side [E] to which the solar DDCs 21 and 22 are connected and power from the output side [F] to which the high-voltage battery 50 is connected. For example, the input and output power of the high-voltage DDC 30 can be obtained by detecting the input and output power of the high-voltage DDC 30 using a power sensor (not shown), or by extracting the input and output power from the input and output voltages and currents of the high-voltage DDC 30 detected using a voltage sensor (not shown) and a current sensor (not shown).

[0023] The auxiliary DDC 40 is a DC-DC converter (third DC-DC converter) that supplies power from the solar DDCs 21 and 22 to the auxiliary battery 60. When the auxiliary DDC 40 supplies power, it converts (steps down) the output voltage of the solar DDCs 21 and 22 (which are input voltages) to a predetermined voltage and outputs that voltage to the auxiliary battery 60. In this embodiment, the auxiliary DDC 40 consists of two or more converter circuits connected in parallel to increase the output power capacity.

[0024] Figure 2 An example of a detailed circuit for an auxiliary DDC 40 consisting of two converter circuits connected in parallel is shown. Figure 2In the auxiliary DDC 40 shown, a first converter circuit composed of switching elements M11, M12, and inductor L1, and a second converter circuit composed of switching elements M21, M22, and inductor L2 are connected in parallel. The switching operation of each switching element M11, M12, M21, and M22 is controlled by a drive circuit 41. The auxiliary DDC 40 includes an input voltage sensor 42, an input current sensor 43, an output voltage sensor 44, a first output current sensor 45, and a second output current sensor 46. The input voltage sensor 42 detects the voltage on the input side [G]. The input current sensor 43 detects the current flowing into the circuit from the input side [G]. The output voltage sensor 44 detects the voltage on the output side [H]. The first output current sensor 45 detects the current flowing from the first converter circuit to the output side [H]. The second output current sensor 46 detects the current flowing from the second converter circuit to the output side [H]. The voltage and current values ​​detected by these sensors, or the power values ​​of the input side [G] and the output side [H] derived from the voltage and current, are output to the processing unit 100. When performing the second example of abnormal control processing (described later), the input current sensor 43 can be omitted.

[0025] Each of the high-voltage DDC 30 and the auxiliary DDC 40 serves as a second power conversion device capable of converting input power from solar DDCs 21 and 22 into desired output power, wherein each of the solar DDCs 21 and 22 is a first power conversion device.

[0026] The high-voltage battery 50 is, for example, a rechargeable secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. The high-voltage battery 50 is connected to the high-voltage DDC 30 so that it can be charged using the power output from the high-voltage DDC 30. The high-voltage battery 50 installed in the vehicle can be, for example, a so-called drive battery capable of providing the power required for the operation of the main devices (not shown) for driving the vehicle, such as the starter motor and the electric motor.

[0027] The auxiliary battery 60 is, for example, a rechargeable secondary battery such as a lithium-ion battery or a lead-acid battery. The auxiliary battery 60 is connected to the auxiliary DDC 40 so that it can be charged using the power output from the auxiliary DDC 40. The auxiliary battery 60 installed in the vehicle is a battery capable of providing the necessary power for the operation of components including vehicle lights (such as headlights and interior lights), air conditioning (such as heaters and coolers), and auxiliary devices (not shown) used for autonomous driving and advanced driver assistance, but not for driving the vehicle itself.

[0028] A capacitor 70 is connected between the solar DDCs 21 and 22 (first power conversion devices) and the high-voltage DDC 30 and auxiliary DDC 40 (second power conversion devices). The capacitor 70 is a large-capacity capacitor used, for example, to charge or discharge the power generated at the solar panels 11 and 12 as needed, or to stabilize the voltage generated between the output of the solar DDCs 21 and 22 and the inputs of the high-voltage DDC 30 and auxiliary DDC 40. The capacitor 70 can be omitted from the components of the solar charging system 1.

[0029] Processing unit 100 acquires detected input power (or detected input voltage and detected input current for derivation) and detected output power (or detected output voltage and detected output current for derivation) from each of solar DDC 21, solar DDC 22, high-voltage DDC 30, and auxiliary DDC 40. When an anomaly exists in the solar charging system 1, processing unit 100 identifies the DC-DC converter with an anomaly (sensor anomaly, circuit anomaly, etc.) based on the input power and output power acquired from each of solar DDC 21, solar DDC 22, high-voltage DDC 30, and auxiliary DDC 40.

[0030] One or more of the solar DDCs 21 and 22, the high-voltage DDC 30, the auxiliary DDC 40, and the processing unit 100 can be configured as an electronic control unit (ECU) that typically includes a processor, memory, input / output interfaces, etc. The ECU is able to perform the various controls described above by reading programs stored in memory and running these programs through the processor.

[0031] control

[0032] Next, we will refer to Figures 3 to 5 Further description includes some examples of the exception control processes performed by the solar charging system 1 when an anomaly exists in the solar charging system 1.

[0033] (1) First example

[0034] Figure 3 This is a flowchart illustrating a first example of an abnormal control process performed by the processing unit 100 of the solar charging system 1. Figure 3 The exception control process in the first example shown begins, for example, when the vehicle's ignition is turned on.

[0035] Step S301

[0036] Processing unit 100 calculates the current difference of auxiliary DDC 40. The current difference of auxiliary DDC 40 is the difference between the current output from the first converter circuit (M11, M12, L1) of auxiliary DDC 40 and the current output from the second converter circuit (M21, M22, L2) of auxiliary DDC 40. Processing unit 100 obtains the current values ​​detected by the first output current sensor 45 and the second output current sensor 46 from auxiliary DDC 40, and calculates the current difference by taking the difference between these values. When auxiliary DDC 40 consists of three or more converter circuits connected in parallel, the difference between any two currents flowing through the converter circuits is calculated. When the current difference of auxiliary DDC 40 is calculated, the process proceeds to step S302.

[0037] Step S302

[0038] Processing unit 100 determines whether the current difference of auxiliary DDC 40 is abnormal. The determination is based on whether the absolute value of the current difference between the first converter circuit (M11, M12, L1) and the second converter circuit (M21, M22, L2) of auxiliary DDC 40 exceeds a predetermined threshold. Taking into account variations and performance of switching elements, inductors, and output current sensors, the predetermined threshold can be set to a predetermined value based on the allowable current difference when both the first and second converter circuits are operating normally. When the current difference of auxiliary DDC 40 is abnormal (yes in step S302), the process proceeds to step S303. When the current difference of auxiliary DDC 40 is normal (no in step S302), the abnormal control process of the first example ends.

[0039] Step S303

[0040] Processing unit 100 calculates the power balance between the input and output of each of solar DDC 21, solar DDC 22, and high-voltage DDC 30. More specifically, processing unit 100 obtains the power (or the derived input voltage and input current) from the input side [A] and the output side [B] of solar DDC 21, and calculates the difference between the obtained input power and output power as the power balance of solar DDC 21. Processing unit 100 obtains the power (or the derived input voltage and input current) from the input side [C] and the output side [D] of solar DDC 22, and calculates the difference between the obtained input power and output power as the power balance of solar DDC 22. Processing unit 100 acquires the power (or the input voltage and input current used for derivation) from the input side [E] of high-voltage DDC 30 and the power (or the output voltage and output current used for derivation) from the output side [F] of high-voltage DDC 30, and calculates the difference between the acquired input power and output power as the power balance of high-voltage DDC 30. When acquiring voltage, the output side [B] of solar DDC 21, the output side [D] of solar DDC 22, and the input side [E] of high-voltage DDC 30 are electrically connected and have the same potential, so any voltage can be used for the other voltage. When the power balance between the input and output of solar DDC 21, the power balance between the input and output of solar DDC 22, and the power balance between the input and output of high-voltage DDC 30 are calculated, the processing proceeds to step S304.

[0041] Step S304

[0042] Processing unit 100 determines whether the power balance between the input and output of solar DDC 21, solar DDC 22, and high-voltage DDC 30 is normal. This determination is performed to determine whether solar DDC 21, solar DDC 22, and high-voltage DDC 30 are operating normally. Specifically, when the DC-DC converter is operating normally, the input power and output power are substantially equal. Therefore, processing unit 100 compares the input power with the output power and determines whether the operation is normal or abnormal based on whether the difference is less than or equal to a predetermined value close to zero. When all power balances of the DDCs are normal (yes in step S304), the process proceeds to step S305. When at least one of the power balances of the DDCs is abnormal (no in step S304), the process proceeds to step S309.

[0043] Step S305

[0044] Processing unit 100 calculates the power balance at the intermediate point between solar DDC 21, solar DDC 22, high-voltage DDC 30, auxiliary DDC 40, and capacitor 70. More specifically, processing unit 100 calculates the power balance of the output of solar DDC 21, the output of solar DDC 22, the input of high-voltage DDC 30, the input of auxiliary DDC 40, and the power line (intermediate point) to which capacitor 70 is connected. Processing unit 100 acquires the power (or the output voltage and output current used for deriving) from the output side [B] of solar DDC 21, the power (or the output voltage and output current used for deriving) from the output side [D] of solar DDC 22, the power (or the input voltage and input current used for deriving) from the input side [E] of high voltage DDC 30, the power (or the input voltage and input current used for deriving) from the input side [G] of auxiliary DDC 40, and the charging and discharging power (terminal voltage and input and output current) of capacitor 70, and calculates the difference (XY) between the sum of the acquired output power and discharge power X (=[B]+[D]+(discharge power)) and the sum of the acquired input power and charging power Y (=[E]+[G]+(charging power)) as the power balance at the intermediate point. Since the voltage at the midpoint is the same value (the same potential) at any of the output sides of solar DDC 21, solar DDC 22, high-voltage DDC 30, auxiliary DDC 40, and capacitor 70, it is possible to determine whether the operation is normal or abnormal, even when calculating current balance instead of power balance (described later). When the power balance at the midpoint between the DDC and the capacitor is calculated, the process proceeds to step S306.

[0045] Step S306

[0046] Processing unit 100 determines whether the power balance at the intermediate point between solar DDC 21, solar DDC 22, high-voltage DDC 30, auxiliary DDC 40, and capacitor 70 is normal. This determination is performed to determine whether the abnormality in auxiliary DDC 40 occurs on the input side [G] or on the output side [H]. Specifically, when the input side [G] of auxiliary DDC 40 is normal, the input and output power at the intermediate point between solar DDC 21, solar DDC 22, high-voltage DDC 30, and auxiliary DDC 40, which are determined to be operating normally, are substantially equal to each other. Therefore, processing unit 100 compares the input power with the output power and determines whether the operation is normal or abnormal based on whether the difference is less than or equal to a predetermined value close to zero. When the power balance at the intermediate point is normal (yes in step S306), the process proceeds to step S307. On the other hand, when the power balance at the intermediate point is abnormal (no in step S306), the process proceeds to step S308.

[0047] Step S307

[0048] Processing unit 100 identifies that the anomaly is only in auxiliary DDC 40 and that the location of the anomaly is on the output side of auxiliary DDC 40 [H]. When the location of the anomaly in auxiliary DDC 40 is identified, the processing proceeds to step S310.

[0049] Step S308

[0050] Processing unit 100 identifies that the anomaly is only in auxiliary DDC 40 and that the location of the anomaly is on the input side of auxiliary DDC 40 [G]. When the location of the anomaly in auxiliary DDC 40 is identified, the processing proceeds to step S311.

[0051] Step S309

[0052] Processing unit 100 determines that an anomaly exists in one of the multiple DDCs. The multiple DDCs include auxiliary DDC 40 and the DDC that was determined to have an abnormal power balance between input and output in step S304. When an anomaly is determined in one of the multiple DDCs, the process proceeds to step S311.

[0053] Step S310

[0054] Processing unit 100 performs fault protection processing on auxiliary DDC 40 where an abnormality exists on the output side [H]. The fault protection processing will be described later. When fault protection processing is performed on auxiliary DDC 40, the abnormality control processing of the first example ends.

[0055] Step S311

[0056] The processing unit 100 determines that the charging process of the electricity generated by the solar panels 11 and 12 can no longer continue and stops the solar charging system 1. Therefore, the abnormal control process of the first example ends.

[0057] Through the processing in steps S301 to S311, when an anomaly exists in the solar charging system 1, the DDC with the anomaly (sensor anomaly, circuit anomaly, etc.) can be accurately identified. Furthermore, in the auxiliary DDC 40, which employs a parallel configuration of converter circuits, it can be accurately determined whether the anomaly occurs on the input side or the output side.

[0058] Figure 4 This is a flowchart illustrating an example of fault protection processing for assisting the DDC 40, which is handled by the processing unit 100 of the solar charging system 1. Figure 3 The procedure is executed in step S310.

[0059] Step S401

[0060] Processing unit 100 calculates the power balance between the input and output of the first converter circuit (M11, M12, L1) of the auxiliary DDC 40. More specifically, with the drive circuit 41 operating the first converter circuit and the second converter circuit stopped, processing unit 100 acquires the voltage of input voltage sensor 42 and the current of input current sensor 43 and calculates the input power of the first converter circuit; it also acquires the voltage of output voltage sensor 44 and the current of first output current sensor 45 and calculates the output power of the first converter circuit. Processing unit 100 calculates the difference between the calculated input power and output power as the power balance between the input and output of the first converter circuit of the auxiliary DDC 40. When the power balance of the first converter circuit is calculated, the process proceeds to step S402.

[0061] Step S402

[0062] Processing unit 100 calculates the power balance between the input and output of the second converter circuit (M21, M22, L2) of the auxiliary DDC 40. More specifically, when the drive circuit 41 stops the first converter circuit and the second converter circuit is running, processing unit 100 acquires the voltage of input voltage sensor 42 and the current of input current sensor 43 and calculates the input power of the second converter circuit; it also acquires the voltage of output voltage sensor 44 and the current of second output current sensor 46 and calculates the output power of the second converter circuit. Processing unit 100 calculates the difference between the calculated input power and output power as the power balance between the input and output of the second converter circuit of the auxiliary DDC 40. When the power balance of the second converter circuit is calculated, the process proceeds to step S403.

[0063] Step S403

[0064] Processing unit 100 determines whether the power balance between the input and output of the first converter circuit (M11, M12, L1) and the second converter circuit (M21, M22, L2) in the auxiliary DDC 40 are both abnormal. This determination is performed to determine whether one of the parallel converter circuits is operating normally. Specifically, when the converter circuit is operating normally, the input power and output power are substantially equal to each other. Therefore, processing unit 100 compares the input power and output power and determines whether the operation is normal or abnormal based on whether the difference is less than or equal to a predetermined value close to zero. When the power balance of both converter circuits is abnormal (yes in step S403), the process proceeds to step S404. When the power balance of one of the converter circuits is abnormal (no in step S403), the process proceeds to step S405.

[0065] Step S404

[0066] The processing unit 100 identifies both the first converter circuit (M11, M12, L1) and the second converter circuit (M21, M22, L2) as abnormal positions and stops the auxiliary DDC 40. In other words, the solar charging system 1 stops. Therefore, the fault protection processing for the auxiliary DDC 40 ends.

[0067] Step S405

[0068] The processing unit 100 identifies one of the first converter circuits (M11, M12, L1) and the second converter circuit (M21, M22, L2) of the auxiliary DDC 40 as being in an abnormal position, and identifies the other as being in normal condition. The processing unit 100 continues the operation of the solar charging control system by using the normally operating converter circuit. When the operation of the solar charging control continues, the fault protection processing for the auxiliary DDC 40 ends.

[0069] Through the processing in steps S401 to S405, even if an anomaly exists in the solar charging system 1, but the anomaly is only in one of the parallel converter circuits in the auxiliary DDC 40, the system can continue to operate the solar charging control by using the normal converter circuit. This control improves the operating rate of the auxiliary DDC 40 in fault protection processing, thus enhancing the reliability of the system's auxiliary DDC 40.

[0070] In the first example, the processing for the case where there are two converter circuits has been described. When the auxiliary DDC 40 consists of three or more converter circuits connected in parallel, the power balance between the input and output of each converter circuit can be calculated, and it can be determined whether all power balances are abnormal. As described in the abnormal control processing of the first example, when a sensor abnormality occurs on the input side [G] of the auxiliary DDC 40 (step S308), the solar charging system 1 immediately stops. However, even if a sensor abnormality occurs on the input side [G] of the auxiliary DDC 40, if the fault protection processing determines that any one of the converter circuits of the auxiliary DDC 40 is normal, the power can be converted by using the normally operating converter circuit, and thus the operation of the solar charging control of the system can continue. However, in this case, it is assumed that at least one of the solar DDC 21 and solar DDC 22 is normal, and the power generated by the solar panel is supplied to the auxiliary DDC 40 by the normal solar DDC.

[0071] (2) Second example

[0072] Figure 5 This is a flowchart illustrating a second example of an anomaly control process performed by the processing unit 100 of the solar charging system 1. This second example of anomaly control processing can be used, for example, in situations where the processing unit 100 cannot detect the current flowing from the input side [G] of the auxiliary DDC 40, such as when the input current sensor 43 of the auxiliary DDC 40 is not configured (see...). Figure 2 (The situation is as follows.) Figure 5 The abnormal control process in the second example shown begins, for example, when the vehicle's ignition is turned on.

[0073] Step S501

[0074] Processing unit 100 calculates the current difference of auxiliary DDC 40. The current difference of auxiliary DDC 40 is the difference between the current output from the first converter circuit (M11, M12, L1) of auxiliary DDC 40 and the current output from the second converter circuit (M21, M22, L2) of auxiliary DDC 40. Processing unit 100 obtains the current values ​​detected by the first output current sensor 45 and the second output current sensor 46 from auxiliary DDC 40, and calculates the current difference by taking the difference between these values. When the current difference of auxiliary DDC 40 is calculated, the process proceeds to step S502.

[0075] Step S502

[0076] The processing unit 100 determines whether the current difference of the auxiliary DDC 40 is abnormal. The determination is based on whether the absolute value of the current difference between the first converter circuit (M11, M12, L1) and the second converter circuit (M21, M22, L2) of the auxiliary DDC 40 exceeds a predetermined threshold. Taking into account variations and performance of switching elements, inductors, and output current sensors, the predetermined threshold can be set to a predetermined value based on the allowable current difference when both the first and second converter circuits are operating normally. When the current difference of the auxiliary DDC 40 is abnormal (yes in step S502), the process proceeds to step S503. On the other hand, when the current difference of the auxiliary DDC 40 is normal (no in step S502), the abnormal control processing of the second example ends.

[0077] Step S503

[0078] Processing unit 100 calculates the power balance between the input and output of each of solar DDC 21, solar DDC 22, and high-voltage DDC 30. More specifically, processing unit 100 obtains the power (or the derived input voltage and input current) from the input side [A] and the output side [B] of solar DDC 21, and calculates the difference between the obtained input power and output power as the power balance of solar DDC 21. Processing unit 100 obtains the power (or the derived input voltage and input current) from the input side [C] and the output side [D] of solar DDC 22, and calculates the difference between the obtained input power and output power as the power balance of solar DDC 22. Processing unit 100 acquires the power (or the derived input voltage and current) from the input side [E] of high-voltage DDC 30 and the power (or the derived output voltage and current) from the output side [F] of high-voltage DDC 30, and calculates the difference between the acquired input power and output power as the power balance of high-voltage DDC 30. When acquiring voltage, the output side [B] of solar DDC 21, the output side [D] of solar DDC 22, and the input side [E] of high-voltage DDC 30 are electrically connected and have the same potential, so any voltage can be used for the other voltage. When the power balance between the input and output of solar DDC 21, the input and output of solar DDC 22, and the input and output of high-voltage DDC are calculated, the processing proceeds to step S504.

[0079] Step S504

[0080] Processing unit 100 determines whether the power balance between the input and output of solar DDC 21, solar DDC 22, and high-voltage DDC 30 is normal. This determination is performed to determine whether solar DDC 21, solar DDC 22, and high-voltage DDC 30 are operating normally. Specifically, when the DC-DC converter is operating normally, the input power and output power are substantially equal. Therefore, processing unit 100 compares the input power with the output power and determines whether the operation is normal or abnormal based on whether the difference is less than or equal to a predetermined value close to zero. When all the power balances of the DDCs are normal (yes in step S504), the process proceeds to step S505. When at least one of the power balances of the DDCs is abnormal (no in step S504), the process proceeds to step S508.

[0081] Step S505

[0082] Processing unit 100 calculates the input power of auxiliary DDC 40 from the power at the midpoint between solar DDC 21, solar DDC 22, high-voltage DDC 30, and capacitor 70. More specifically, processing unit 100 acquires the power (or the output voltage and output current used for derivation) from the output side [B] of solar DDC 21, the power (or the output voltage and output current used for derivation) from the output side [D] of solar DDC 22, the power (or the input voltage and input current used for derivation) from the input side [E] of high-voltage DDC 30, and the charging and discharging power (terminal voltage and input and output current) of capacitor 70, and calculates the value (XZ) obtained by subtracting the sum of input power and charging power (Z) (= [E] + (charging power)) from the sum of acquired output power and discharging power X (= [B] + [D] + (discharging power)). When the input power of auxiliary DDC 40 is calculated, the processing proceeds to step S506.

[0083] Step S506

[0084] Processing unit 100 calculates the power balance between the input and output of the first converter circuit (M11, M12, L1) of the auxiliary DDC 40. More specifically, with the drive circuit 41 operating the first converter circuit and the second converter circuit stopped, processing unit 100 acquires the voltage of input voltage sensor 42 and the current of input current sensor 43 and calculates the input power of the first converter circuit; it also acquires the voltage of output voltage sensor 44 and the current of first output current sensor 45 and calculates the output power of the first converter circuit. Processing unit 100 calculates the difference between the calculated input power and output power as the power balance between the input and output of the first converter circuit of the auxiliary DDC 40. Processing unit 100 also calculates the power balance between the input and output of the second converter circuit (M21, M22, L2) of the auxiliary DDC 40. More specifically, when the driving circuit 41 stops the first converter circuit and the second converter circuit is running, the processing unit 100 acquires the voltage of the input voltage sensor 42 and the current of the input current sensor 43 and calculates the input power of the second converter circuit; it also acquires the voltage of the output voltage sensor 44 and the current of the second output current sensor 46 and calculates the output power of the second converter circuit. The processing unit 100 calculates the difference between the calculated input power and output power as the power balance between the input and output of the second converter circuit of the auxiliary DDC 40. When the power balance of the first converter circuit and the power balance of the second converter circuit are calculated, the process proceeds to step S507.

[0085] Step S507

[0086] Processing unit 100 determines whether the power balance between the input and output of the first converter circuit (M11, M12, L1) and the second converter circuit (M21, M22, L2) in the auxiliary DDC 40 are both abnormal. This determination is performed to determine whether one of the parallel converter circuits is operating normally. Specifically, when the converter circuit is operating normally, the input power and output power are substantially equal to each other. Therefore, processing unit 100 compares the input power and output power and determines whether the operation is normal or abnormal based on whether the difference is less than or equal to a predetermined value close to zero. When the power balance of both converter circuits is abnormal (yes in step S507), the process proceeds to step S509. On the other hand, when the power balance of one of the converter circuits is abnormal (no in step S507), the process proceeds to step S510.

[0087] Step S508

[0088] Processing unit 100 determines that an anomaly exists in one of the multiple DDCs. The multiple DDCs include auxiliary DDC 40 and the DDC that was determined to have an abnormal power balance between input and output in step S504. When an anomaly is determined in one of the multiple DDCs, the process proceeds to step S509.

[0089] Step S509

[0090] Processing unit 100, for example, determines that charging of electricity generated by solar panels 11 and 12 cannot continue due to anomalies in both the first converter circuit (M11, M12, L1) and the second converter circuit (M21, M22, L2), and stops the auxiliary DDC 40 and the solar charging system 1. Therefore, the anomaly control processing of the second example ends.

[0091] Step S510

[0092] Since one of the first converter circuits (M11, M12, L1) and the second converter circuit (M21, M22, L2) of the auxiliary DDC 40 is operating normally, the processing unit 100 continues the operation of the solar charging control system by using the normally operating converter circuit (fault protection processing). While the operation of the solar charging control continues, the abnormal control processing of the second example ends.

[0093] Through the processing in steps S501 to S510, when an anomaly exists in the solar charging system 1, the DDC with the anomaly (sensor anomaly, circuit anomaly, etc.) can be accurately identified. Even when the current flowing from the input side [G] of the auxiliary DDC 40 cannot be obtained, if the location of the anomaly is only one of the parallel converter circuits in the auxiliary DDC 40, the solar charging control can continue to operate using the normal converter circuit. Through this control, the operating rate of the auxiliary DDC 40 in fault protection processing is improved, thus improving the reliability of the auxiliary DDC 40 and the system.

[0094] (3) Application Examples

[0095] The fault control processing in the first and second examples mainly involves determining whether an fault exists in the auxiliary DDC 40, which consists of parallel converter circuits. However, the solar charging system 1 according to this embodiment has a configuration in which two panel power generation control units are arranged in parallel. Therefore, fault protection processing similar to that used for the converter circuit of the auxiliary DDC 40 can be applied to the parallel solar DDCs 21 and 22. In other words, when a power balance abnormality exists only in either solar DDC 21 or solar DDC 22, power can be provided by continuing to generate electricity using one of the solar panels through the normally operating solar DDC. The fault protection processing of the solar DDC also applies to the case where only one converter circuit is operating in the fault protection processing of the auxiliary DDC 40.

[0096] Operation and benefits

[0097] As described above, using the solar charging system 1 according to an embodiment of the present disclosure, when an anomaly exists in the system, the DC-DC converter in which the anomaly exists (the location of the anomaly) can be accurately identified based on the power balance between the input and output of each of the solar DDC 21, solar DDC 22, high voltage DDC 30 and auxiliary DDC 40, the power balance at intermediate points, etc.

[0098] In the solar charging system 1 according to this embodiment, when the auxiliary DDC 40, which is malfunctioning, consists of parallel converter circuits, the malfunctioning converter circuit (one or both) can be identified based on the current difference (the difference between the current output from the first converter circuit of the auxiliary DDC 40 and the current output from the second converter circuit of the auxiliary DDC 40), the power balance between the input and output of the first converter circuit, and the power balance between the input and output of the second converter circuit. Furthermore, when only one converter circuit is malfunctioning, the system can continue operating the solar charging control by using a normal converter circuit, thus improving the operating rate of the auxiliary DDC 40 and enhancing the reliability of both the auxiliary DDC 40 and the system.

[0099] Embodiments of the technology disclosed herein have been described; however, this disclosure is not limited to solar charging systems. This disclosure can also be interpreted as a method performed by a solar charging system, a program implementing that method, a non-transitory computer-readable storage medium storing a program, a vehicle including a solar charging system, etc.

[0100] The solar charging system disclosed herein can be used in vehicles and the like that use electricity generated by solar panels to charge batteries.

Claims

1. A solar charging system, characterized in that... include: Solar panels; The first power conversion device is configured as follows: Receives power generated by the solar panel, and Detect or export the input and output power of the first power conversion device; as well as The second power conversion device is configured as follows: Receives power output from the first power conversion device, and Detect or export the input and output power of the second power conversion device. The solar panel is composed of multiple solar panels; The first power conversion device consists of a plurality of first DC-DC converters respectively arranged corresponding to the plurality of solar panels; and The second power conversion device includes The second DC-DC converter is configured as follows: Detect or export the input and output power of the second DC-DC converter, and The power input from the first power conversion device is output to the first battery, and The third DC-DC converter is configured as follows: Detect or export the output power of the third DC-DC converter, and The power input from the first power conversion device is output to the second battery. The solar charging system further includes an electronic control unit configured to, when an anomaly occurs in the solar charging system, determine whether an anomaly has occurred in at least one of the first DC-DC converter and the second DC-DC converter, based on a comparison between the input power and the output power of the first power conversion device and a comparison between the input power and the output power of the second power conversion device. The third DC-DC converter is configured to connect two or more converter circuits in parallel; and The electronic control unit is configured to determine whether an abnormality has occurred in the third DC-DC converter based on the difference between any two currents flowing through the two or more converter circuits.

2. The solar charging system according to claim 1, characterized in that... The electronic control unit is configured to, when the electronic control unit determines that an abnormality has occurred in the third DC-DC converter, identify the location of the abnormality in the third DC-DC converter based on i) a comparison between the output power values ​​of each of the first DC-DC converters and ii) a comparison between the input power values ​​of the second DC-DC converters and the input power values ​​of the third DC-DC converter.

3. The solar charging system according to claim 1, characterized in that... The electronic control unit is configured to, when the electronic control unit determines that an abnormality has occurred in the third DC-DC converter, identify the location of the abnormality in the third DC-DC converter based on iii) a comparison between the value of the difference between the sum of the input power of the second DC-DC converter and the output power of the first DC-DC converter and iv) the output power of the third DC-DC converter.

4. The solar charging system according to claim 2, characterized in that... It also includes a capacitor connected between the first power conversion device and the second power conversion device, wherein The electronic control unit is configured to, when the electronic control unit determines that an abnormality has occurred in the third DC-DC converter, identify the location of the abnormality in the third DC-DC converter based on a comparison between v) the sum of the output power of the first DC-DC converter and the discharge power of the capacitor and vi) the sum of the input power of the second DC-DC converter, the input power of the third DC-DC converter, and the charging power of the capacitor.

5. The solar charging system according to claim 3, characterized in that... It also includes a capacitor connected between the first power conversion device and the second power conversion device, wherein The electronic control unit is configured to, when the electronic control unit determines that an abnormality has occurred in the third DC-DC converter, identify the location of the abnormality in the third DC-DC converter based on vii) the difference between the sum of the output power of the first DC-DC converter and the discharge power of the capacitor and the sum of the input power of the second DC-DC converter and the charging power of the capacitor, and viii) a comparison between the output power of the third DC-DC converter.

6. The solar charging system according to any one of claims 2 to 5, characterized in that... The electronic control unit is configured to, when the electronic control unit determines that an abnormality has occurred in the third DC-DC converter, identify the converter circuit in which the abnormality has occurred based on a comparison between the input power and the output power of each of the two or more converter circuits.

7. The solar charging system according to any one of claims 2 to 5, characterized in that: The two or more converter circuits include a first converter circuit and a second converter circuit; and The electronic control unit is configured to, when the electronic control unit determines that an abnormality has occurred in the third DC-DC converter, identify either the first converter circuit or the second converter circuit that has experienced the abnormality based on a comparison between the input power and output power of the first converter circuit and a comparison between the input power and output power of the second converter circuit.

8. The solar charging system according to claim 6, characterized in that... The electronic control unit is configured to continue control by using the converter circuit in which no abnormality has occurred.

9. The solar charging system according to claim 7, characterized in that... The electronic control unit is configured to continue control by using the converter circuit in which no abnormality has occurred.

10. A method performed by a solar charging system, the solar charging system comprising... Solar panels, A first DC-DC converter is configured to receive power generated by the solar panel. A second DC-DC converter is configured to detect or export the input and output power of the second DC-DC converter, and to output the power input from the first DC-DC converter to the first battery. A third DC-DC converter, configured to detect or export the output power of the third DC-DC converter and output the power input from the first DC-DC converter to a second battery, the method being characterized by comprising: When an anomaly occurs in the solar charging system, the location of the anomaly is identified based on the input and output power of the first DC-DC converter, the input and output power of the second DC-DC converter, and the input and output power of the third DC-DC converter. The solar charging system further includes an electronic control unit configured to, when an anomaly occurs in the solar charging system, determine whether an anomaly has occurred in at least one of the first DC-DC converter and the second DC-DC converter, based on a comparison between the input power and the output power of the first DC-DC converter and a comparison between the input power and the output power of the second DC-DC converter. The third DC-DC converter is configured to connect two or more converter circuits in parallel; and The electronic control unit is configured to determine whether an abnormality has occurred in the third DC-DC converter based on the difference between any two currents flowing through the two or more converter circuits.

11. A vehicle, characterized in that... Includes the solar charging system according to any one of claims 1 to 9.

Images