Charging control device

Abstract

To provide a charge control device which can prevent deterioration of a battery in charge state determination.SOLUTION: A charge state determination unit of an ECU applies generated voltage set by a generated voltage setting unit on the basis of battery temperature to a battery and determines a charge state of the battery on the basis of charge current of the battery in application of the generated voltage (a step S4) when a discharge integrated amount is high (YES in a step S3) in initial startup after soak (YES in a step S2). The generated voltage setting unit sets the generated voltage to voltage lower than in the case that the battery temperature is intermediate temperature when the battery temperature is higher than the predetermined intermediate temperature. The generated voltage setting unit sets the generated voltage to voltage higher than in the case that the battery temperature is the intermediate temperature when the battery temperature is lower than the predetermined intermediate temperature.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a charge control device. [Background technology]

[0002] Patent Document 1 describes a technology in which, when an ignition-on signal is input, a charging control unit charges a battery for a predetermined determination time Tr, so that a battery storage state determination unit determines the battery storage state SOC of the battery immediately after the engine starts, and a battery storage state recognition unit calibrates the recognized battery storage state SOCr. In the technology described in Patent Document 1, the charging voltage to the battery when determining the battery storage state SOC is set to 14.5 V. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 072091 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology described in Patent Document 1, the charging voltage to the battery when determining the state of charge SOC is always set to a constant voltage, which means there is a risk of the battery being degraded when determining the state of charge SOC.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide a charge control device that can prevent deterioration of a battery when determining the state of charge. [Means for solving the problem]

[0006] The present invention is a charge control device for controlling charging from a generator to a battery, the charge control device including: a power generation control unit for controlling the generator so as to generate power at a set generation voltage; a charge current detection unit for detecting a charging current to the battery; a charge state determination unit for determining a charging state of the battery based on the charging current detected by the charge current detection unit; a temperature detection unit for detecting the temperature of the battery as a battery temperature; When the battery temperature is higher than a predetermined intermediate temperature, the generated voltage is set to a lower voltage than when the battery temperature is the intermediate temperature, and when the battery temperature is lower than the intermediate temperature, the generated voltage is set to a higher voltage than when the battery temperature is the intermediate temperature. and a power generation voltage setting unit that sets a power generation voltage, When the system is started for the first time by turning the ignition key on after the vehicle has been parked, The generated voltage setting unit sets the generated voltage based on the battery temperature. The above A generated voltage is applied to the battery, and the charging state is determined based on the charging current of the battery when the generated voltage is applied. Then, the deviation from the accumulated discharge amount is detected, the accumulated discharge amount is corrected, and the charge / discharge operation is performed. It is characterized by: Effect of the Invention

[0007] As described above, according to the present invention, it is possible to provide a charge control device that can prevent deterioration of the battery when the state of charge is determined. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram of a vehicle equipped with a charge control device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a flowchart illustrating a charging state determination operation of the charging control device according to one embodiment of the present invention. [Diagram 3] FIG. 3 shows a generation voltage setting map that defines the relationship between the battery temperature and the generation voltage and that is referred to by the charge control device according to one embodiment of the present invention during the operation of determining the state of charge. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A charge control device according to one embodiment of the present invention is a charge control device that controls charging from a generator to a battery, and includes a power generation control unit that controls the generator to generate power at a set generation voltage, a charge current detection unit that detects a charging current to the battery, a charge state determination unit that determines the state of charge of the battery based on the charging current detected by the charge current detection unit, a temperature detection unit that detects the temperature of the battery as the battery temperature, and a generation voltage setting unit that sets the generation voltage of the generator based on the battery temperature, and is characterized in that the charge state determination unit applies to the battery the generation voltage set by the generation voltage setting unit based on the battery temperature, and determines the state of charge based on the charging current of the battery when the generation voltage is applied. As a result, the charge control device according to one embodiment of the present invention can prevent deterioration of the battery when determining the state of charge. EXAMPLES

[0010] An embodiment of the present invention will be described in detail below with reference to the drawings. In Fig. 1, a vehicle 1 equipped with a charge control device according to an embodiment of the present invention includes an alternator 3 as a generator, a battery 5 capable of charging the electric power generated by the alternator 3, and an ECU (Electronic Control Unit) 10 as a charge control device.

[0011] The vehicle 1 is equipped with an internal combustion engine (not shown) mechanically connected to an alternator 3, and power generated by the engine is transmitted to the alternator 3. The engine is, for example, a four-stroke engine in which a series of four strokes consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke are performed while the piston reciprocates twice within the cylinder, and ignition is performed between the compression stroke and the expansion stroke.

[0012] The alternator 3 generates electricity by rotating using the driving force transmitted from the engine. The alternator 3 generates a voltage according to a generation voltage command value from the ECU 10.

[0013] The battery 5 is a lead-acid battery with a rated voltage of 12 V, stores electricity generated by the alternator 3, and supplies the stored electricity to the electrical load 6. The battery 5 has two electrodes using lead and battery fluid (electrolyte).

[0014] The battery 5, which is a lead-acid battery, is easily affected by the ambient temperature, and has a characteristic that it deteriorates and its lifespan is shortened especially at high temperatures. The battery 5 is not limited to a lead-acid battery, and may be, for example, a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. All types of secondary batteries have a characteristic that they deteriorate at high temperatures.

[0015] The battery 5 is provided with a current sensor 17, which detects the current flowing in and out of the battery 5 and outputs the detected current to the ECU 10. The current detected by the current sensor 17 is the current supplied from the battery 5 to the electric load 6 and the current charged from the alternator 3 to the battery 5.

[0016] The battery 5 is provided with a temperature sensor 18, which detects the temperature of the battery 5 and outputs the temperature to the ECU 10. The temperature detected by the temperature sensor 18 is the temperature of the battery fluid in the battery 5.

[0017] The ECU 10 controls the engine and the alternator 3. The ECU 10 is composed of a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an input port, an output port, and a network module.

[0018] The network module is capable of communicating with other ECUs (not shown) via a network such as a Controller Area Network (CAN) or FlexRay.

[0019] The ROM of the ECU 10 stores various control constants, various maps, and the like, as well as a program for causing the computer unit to function as the ECU 10. That is, in the ECU 10, the CPU executes the program stored in the ROM, causing the computer unit to function as the ECU 10.

[0020] In this embodiment, a current sensor 17 and a temperature sensor 18 are connected to an input port of the ECU 10. Meanwhile, an alternator 3 is connected to an output port of the ECU 10. The ECU 10 controls the power generation voltage of the alternator 3 based on detection signals from the current sensor 17 and the temperature sensor 18, and controls charging from the alternator 3 to the battery 5.

[0021] The ECU 10 includes a power generation control unit 10A, a charging current detection unit 10B, and a charging state determination unit 10C. The power generation control unit 10A controls the alternator 3 so as to generate power at a set power generation voltage (power generation voltage command value). The charging current detection unit 10B detects the charging current to the battery 5. The charging current detection unit 10B detects the charging current by a current sensor 17. The charging state determination unit 10C determines the state of charge (SOC) of the battery 5 based on the charging current detected by the charging current detection unit 10B.

[0022] In this embodiment, the ECU 10 includes a temperature detection unit 10D that detects the temperature of the battery fluid (fluid temperature) of the battery 5 as the battery temperature.

[0023] Furthermore, the ECU 10 includes a generation voltage setting unit 10E, which sets the generation voltage of the alternator 3 based on the battery temperature. Here, the generation voltage of the alternator 3 is equal to the charging voltage of the battery 5. Therefore, the generation voltage setting unit 10E sets the charging voltage of the battery 5 based on the battery temperature.

[0024] The generation voltage setting unit 10E sets the generation voltage of the alternator 3 when determining the state of charge of the battery 5, with reference to a generation voltage setting map shown in Fig. 3. In the generation voltage setting map, the vertical axis represents the state of charge, and the horizontal axis represents the battery temperature. The generation voltage setting map is divided into an appropriate generation voltage region, an undercharge region, and a thermal runaway region.

[0025] The appropriate generation voltage region is a region of appropriate generation voltage according to the battery temperature. In the appropriate generation voltage region, a set generation voltage, which is an optimal generation voltage according to the battery temperature, is set for each battery temperature. The insufficient charging region is a region where the voltage is lower than the appropriate charging voltage, resulting in insufficient charging. The thermal runaway region is a region where the voltage is higher than the appropriate charging voltage, resulting in an excessively high battery temperature. The generation voltage setting unit 10E controls the alternator 3 based on the battery temperature so that the generation voltage becomes the set generation voltage.

[0026] Then, the charge state determination unit 10C applies to the battery 5 the generated voltage set by the generated voltage setting unit 10E based on the battery temperature, and determines the charge state of the battery 5 based on the charging current of the battery 5 when the generated voltage is applied.

[0027] In the generated voltage setting map of FIG. 3, the temperature on the horizontal axis is divided into a predetermined intermediate temperature region, a region higher than the intermediate temperature, and a region lower than the intermediate temperature.

[0028] When the battery temperature is higher than a predetermined intermediate temperature, the generated voltage setting unit 10E sets the generated voltage to a lower voltage than when the battery temperature is the intermediate temperature. Also, when the battery temperature is lower than the predetermined intermediate temperature, the generated voltage setting unit 10E sets the generated voltage to a higher voltage than when the battery temperature is the intermediate temperature.

[0029] It should be noted that the generated voltage setting unit 10E does not perform correction taking into consideration the degree of deterioration of the battery 5, etc., when setting the generated voltage of the alternator 3 at the time of determining the state of charge of the battery 5.

[0030] The charge state determination operation of the charge control device according to this embodiment configured as above will be described below. This charge state determination operation is repeatedly performed at predetermined short intervals while the system is running.

[0031] In step S1, the ECU 10 acquires vehicle and part information. In this step S1, the ECU 10 acquires detection signals from sensors in various parts of the vehicle 1 to protect the parts and stabilize the power supply, and checks whether or not there is an abnormality.

[0032] Next, the ECU 10 determines in step S2 whether or not this is the first start after the soak period. In this step S2, the ECU 10 determines whether or not this is the first system start by turning the ignition key on after the ignition key (not shown) is turned off and the vehicle is parked (soaked), and if the determination is NO, the ECU 10 ends the current operation.

[0033] Next, when the determination in step S2 is YES, the ECU 10 determines whether or not the accumulated discharge amount is high in step S3. In this step S3, the ECU 10 obtains the accumulated amount of discharge current of the battery 5, and determines that the accumulated discharge amount is high if this value is equal to or greater than a threshold value. When the determination in step S2 is NO, the ECU 10 ends this operation.

[0034] If the determination in step S3 is YES, the ECU 10 determines the battery charging current in step S4. In this step S4, the charge state determination unit 10C of the ECU 10 applies to the battery 5 the generated voltage set by the generated voltage setting unit 10E based on the battery temperature, and determines the charge state of the battery 5 based on the charging current of the battery 5 when the generated voltage is applied.

[0035] Next, in step S5, the ECU 10 determines whether or not a deviation in the discharge accumulation amount is to be detected. In this step S5, the ECU 10 determines whether or not a deviation in the discharge accumulation amount needs to be detected and corrected based on the discharge accumulation amount acquired in step S3 and the battery charging current determined in step S4. If the determination is NO, the ECU 10 ends the current operation.

[0036] If it is determined in step S5 that a deviation in the accumulated discharge amount is detected, the deviation is detected and the accumulated discharge amount is calibrated. After that, in step S6, the ECU 10 shifts to an optimal charge / discharge operation after the calibration of the accumulated discharge amount.

[0037] In this manner, in this embodiment, the state of charge of the battery 5 is determined at the initial start after a soak period when the battery 5 is not being charged or discharged by other controls. In addition, the voltage applied to the battery 5 when determining the state of charge is set according to the battery temperature.

[0038] As described above, the charge control device of this embodiment includes a power generation control unit 10A that controls the alternator 3 to generate power at a set generation voltage, a charge current detection unit 10B that detects a charge current to the battery 5, and a charge state determination unit 10C that determines the state of charge of the battery 5 based on the charge current detected by the charge current detection unit 10B. The charge control device of this embodiment also includes a temperature detection unit 10D that detects the temperature of the battery 5 as the battery temperature, and a generation voltage setting unit 10E that sets the generation voltage of the alternator 3 based on the battery temperature. The charge state determination unit 10C applies to the battery 5 the generation voltage set by the generation voltage setting unit 10E based on the battery temperature, and determines the state of charge based on the charging current of the battery 5 when the generation voltage is applied.

[0039] Thereby, when the state of charge of the battery 5 is determined, a power generation voltage set based on the battery temperature is applied from the alternator 3 to the battery 5. As a result, deterioration of the battery 5 when the state of charge is determined can be prevented.

[0040] Furthermore, in the charge control device of this embodiment, when the battery temperature is higher than a predetermined intermediate temperature, the generated voltage setting unit 10E sets the generated voltage to a lower voltage than when the battery temperature is the intermediate temperature.

[0041] This makes it possible to prevent the battery fluid from being reduced due to evaporation when the battery is charged at a high voltage when the battery temperature is high, and thus makes it possible to prevent the battery from deteriorating.

[0042] Furthermore, in the charge control device of this embodiment, when the battery temperature is lower than a predetermined intermediate temperature, the generated voltage setting unit 10E sets the generated voltage to a higher voltage than when the battery temperature is the intermediate temperature.

[0043] This prevents the battery 5 from becoming undercharged when it is charged at a low voltage when the battery temperature is low, and prevents the battery 5 from being overcharged (dead battery) due to undercharging and deterioration of the battery 5 due to overdischarge.

[0044] Although an embodiment of the invention has been disclosed, it will be apparent to one of ordinary skill in the art that modifications may be made therein without departing from the spirit and scope of the invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0045] 3. Alternator (generator) 5 Battery 10 ECU (Charging Control Unit) 10A Power generation control unit 10B Charging current detection section 10C Charging state determination unit 10D Temperature detection unit 10E Power generation voltage setting section

Claims

[Claim 1] A charge control device that controls charging from a generator to a battery, a power generation control unit that controls the generator so as to generate power at a set generation voltage; a charging current detection unit that detects a charging current to the battery; a charge state determination unit that determines a charge state of the battery based on the charging current detected by the charge current detection unit; a temperature detection unit that detects a temperature of the battery as a battery temperature; a generation voltage setting unit that, when the battery temperature is higher than a predetermined intermediate temperature, sets the generation voltage to a lower voltage than when the battery temperature is the intermediate temperature, and, when the battery temperature is lower than the intermediate temperature, sets the generation voltage to a higher voltage than when the battery temperature is the intermediate temperature; a charging control device which applies to the battery the generated power voltage set by the generated power voltage setting unit based on the battery temperature when the system is started for the first time by turning on an ignition key after the vehicle is parked, determines the charged state based on the charging current of the battery at the time of application of the generated power voltage, detects a deviation from an accumulated discharge amount, calibrates the accumulated discharge amount, and performs charging and discharging operations.

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