JP7655041B2 - Charging control device - Google Patents

Description

The present invention relates to a charging control device.

Patent document 1 describes a technology in which, when an ignition-on signal is input, a charging control unit charges the battery for a predetermined determination time Tr, and immediately after the engine starts, a battery storage state determination unit determines the battery storage state SOC, 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 14.5V.

International Publication No. 2016/072091

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 raises the risk of the battery deteriorating when determining the state of charge SOC.

The present invention was made with an eye on the above problems, and aims to provide a charge control device that can prevent deterioration of the battery when determining the charging state.

The present invention is a charge control device that controls charging of a battery from a generator, and includes 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 charging state determination unit that determines a charging state of the battery based on the charging current detected by the charging current detection unit, a temperature detection unit that detects the temperature of the battery as a battery temperature, and 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. The charging state determination unit applies to the battery the generation voltage set by the generation voltage setting unit based on the battery temperature when the system is started for the first time by turning the ignition key on after the vehicle is parked, determines the charging state based on the charging current of the battery at the time of application of the generation voltage , detects a deviation from an accumulated discharge amount, calibrates the accumulated discharge amount, and performs charging and discharging operations .

In this way, according to the present invention, it is possible to provide a charge control device that can prevent deterioration of the battery when determining the charging state.

FIG. 1 is a configuration diagram of a vehicle equipped with a charge control device according to an embodiment of the present invention. FIG. 2 is a flowchart illustrating a charging state determination operation of the charging control device according to one embodiment of the present invention. 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.

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 the charging current to the battery, a charge state determination unit that determines the charging state 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 charging state 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 charging state.

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.

The vehicle 1 is equipped with an internal combustion engine (not shown) that is mechanically connected to an alternator 3, and the power generated by the engine is transmitted to the alternator 3. The engine is, for example, a four-stroke engine that performs a series of four strokes consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while the piston makes two reciprocating movements within the cylinder, and ignites during the compression stroke and the expansion stroke.

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

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 lead-based electrodes and battery fluid (electrolyte).

Battery 5, which is a lead-acid battery, is easily affected by the ambient temperature, and has the characteristic that it deteriorates and its lifespan is shortened especially at high temperatures. Note that 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 the characteristic that they deteriorate at high temperatures.

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

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

The ECU 10 controls the engine and the alternator 3. The ECU 10 is composed of a computer unit that includes 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.

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

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.

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

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 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. This charging current detection unit 10B detects the charging current using a current sensor 17. The charging state determination unit 10C determines the charging state (SOC: State of Charge) of the battery 5 based on the charging current detected by the charging current detection unit 10B.

In this embodiment, the ECU 10 is equipped with a temperature detection unit 10D that detects the temperature of the battery fluid (fluid temperature) of the battery 5 as the battery temperature.

Furthermore, the ECU 10 is equipped with 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.

The power generation voltage setting unit 10E refers to the power generation voltage setting map shown in FIG. 3 to set the power generation voltage of the alternator 3 when determining the state of charge of the battery 5. In the power generation voltage setting map, the vertical axis represents the state of charge, and the horizontal axis represents the battery temperature. The power generation voltage setting map is divided into an appropriate power generation voltage region, an undercharge region, and a thermal runaway region.

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 the 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 the battery temperature becoming too high. 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.

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.

In the power generation voltage setting map in Figure 3, the temperature on the horizontal axis is divided into a region of a specified intermediate temperature, a region higher than the intermediate temperature, and a region lower than the intermediate temperature.

When the battery temperature is higher than a predetermined intermediate temperature, the generation voltage setting unit 10E sets the generation voltage to a lower voltage than when the battery temperature is the intermediate temperature. When the battery temperature is lower than the predetermined intermediate temperature, the generation voltage setting unit 10E sets the generation voltage to a higher voltage than when the battery temperature is the intermediate temperature.

When setting the power generation voltage of the alternator 3 when determining the state of charge of the battery 5, the power generation voltage setting unit 10E does not make any corrections that take into account the degree of deterioration of the battery 5, etc.

The charging state determination operation of the charging control device according to this embodiment configured as described above will now be described. This charging state determination operation is repeatedly performed at a predetermined short interval while the system is running.

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 for the presence or absence of abnormalities.

Next, in step S2, the ECU 10 determines whether or not this is the first start-up after the soak. In this step S2, the ECU 10 determines whether or not this is the first time the system has been started by turning the ignition key on after the ignition key (not shown) has been turned off and the vehicle has been parked (soaked), and if the determination is NO, the current operation is terminated.

Next, if the determination in step S2 is YES, the ECU 10 determines in step S3 whether the accumulated discharge amount is high. In this step S3, the ECU 10 obtains the accumulated amount of discharge current of the battery 5, and if this value is equal to or greater than a threshold value, it determines that the accumulated discharge amount is high. If the determination in step S2 is NO, the ECU 10 ends the current operation.

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.

Next, in step S5, the ECU 10 determines whether or not a deviation in the accumulated discharge amount is detected. In this step S5, the ECU 10 determines whether a deviation in the accumulated discharge amount needs to be detected and calibrated based on the accumulated discharge 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.

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 transitions to the optimal charging and discharging operation after the calibration of the accumulated discharge amount.

In this way, in this embodiment, the state of charge of the battery 5 is determined at the initial start after a soak 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.

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

As a result, 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.

In addition, in the charging control device of this embodiment, when the battery temperature is higher than a predetermined intermediate temperature, the generation voltage setting unit 10E sets the generation voltage to a lower voltage than when the battery temperature is the intermediate temperature.

This prevents the battery fluid from evaporating and decreasing when the battery is charged at high voltage when the battery temperature is high, and prevents battery deterioration.

In addition, in the charging control device of this embodiment, when the battery temperature is lower than a predetermined intermediate temperature, the generation voltage setting unit 10E sets the generation voltage to a higher voltage than when the battery temperature is the intermediate temperature.

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 from deteriorating due to overdischarge.

Although an embodiment of the present invention has been disclosed, it is apparent that modifications may be made by one of ordinary skill in the art without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the following claims.

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

Claims (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 the 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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