JP4700644B2 - Lead battery charge control device - Google Patents

Description

  The present invention relates to a charge control device for a lead battery mounted on a vehicle in combination with a power storage device such as a lithium ion capacitor as a power source for supplying electric power to an electric device.

  As a power supply device for supplying electric power to an electric device such as a starter motor mounted on a vehicle, a power storage device such as a lithium ion capacitor (hereinafter referred to as LIC) is used in addition to a lead battery also referred to as a lead storage battery. The power supply device is charged with electric power generated by an alternator driven by an engine. Comparing the lead battery and the LIC, the lead battery has the characteristics that the internal resistance is larger than that of the LIC and the energy density is higher than that of the LIC, but the output density is lower than that of the LIC. In order to utilize such characteristics, vehicles have been developed in which a power supply device using both a lead battery and an LIC is mounted. Because of this characteristic, even when the vehicle is used in a cold region, the engine can be started by mounting the LIC, and the engine does not start for several months by mounting the lead battery. Even in this case, the engine can be started by reliably driving the starter motor.

Patent Document 1 describes a power supply device in which a lead battery and an electric double layer capacitor are connected in parallel and mounted on a vehicle. On the other hand, in a vehicle in which a lead battery is mounted alone as a power supply device, it is necessary to estimate the remaining capacity (SOC) of the battery or the fully charged state. A remaining capacity detection device is described in which the remaining capacity is calculated based on voltage, charge / discharge current, and the like.
JP 2006-230132 A JP 2000-240502 A

  Whether or not a lead battery is fully charged depends on the initial characteristic data of the lead battery alone, and the initial characteristic data varies greatly depending on the measurement state, charge / discharge rate, temperature conditions, etc. Therefore, it is difficult to determine full charge of the lead battery with high accuracy.

  For example, if a lead battery with an SOC of about 95% is charged at a target voltage of 14.4 V by an alternator with an open-circuit voltage of about 12.8 V, the lead battery will instantaneously rise to the target voltage. . In contrast, when a single LIC is charged near the target voltage by an alternator, the LIC has a characteristic that the voltage increases toward the target voltage with time without instantaneously increasing to the target voltage.

  On the other hand, when a lead battery and LIC are used together and the power supply device connected in parallel is charged near the target voltage by an alternator, the voltage of the lead battery is the voltage before and after the occurrence of charge polarization. The rate of increase was different. It has also been found that the rate of increase in voltage differs between when the lead battery reaches full charge voltage after the occurrence of charge polarization and when it reaches full charge. Charging polarization is a phenomenon in which, when the voltage increases with the progress of charging, the charging energy is used for the chemical reaction of the electrolytic solution and the voltage increase rate decreases. For example, when the lead battery has an open-circuit voltage of about 12.8V, when the alternator is driven to start charging, charging polarization occurs at about 13.5 to 13.6V, and after the charging polarization occurs, the rate of voltage increase of the lead battery However, the voltage of the lead battery connected in parallel to the LIC rises with the same characteristics as when only the LIC is charged. It has been found. Such a phenomenon cannot be determined because only the lead battery is charged by the alternator, and as described above, it instantaneously increases to the target voltage.

  An object of the present invention is to provide a charge control device for a lead battery that accurately determines the full charge state of the lead battery.

The charge control device for a lead battery according to the present invention includes a lead battery, a power supply device having an internal resistance smaller than that of the lead battery and connected in parallel to the lead battery, and a power supply driven by an engine to the power supply device. Current detector for monitoring the current of the lead battery, voltage detector for monitoring the voltage of the power supply device, and current integration for calculating a current integration value based on a signal from the current detection unit And calculating a voltage increase rate of the power supply device during operation of the alternator based on a signal from the voltage detection means and a signal from the voltage detection means under a state where the current integrated value is a positive value. There is higher than the reference value, and the current voltage value of the power supply device which is calculated based on a signal from the voltage detecting means, the target power generation of the alternator When the difference between the pressure equal to or less than the threshold value, characterized in that the lead battery has a full charge determining means for determining that the full charge.

  The charge control device for a lead battery according to the present invention confirms that the lead battery is fully charged when the current value of the lead battery calculated based on a signal from the current detection means becomes a threshold value or less. It is characterized by determining.

  The charge control device for a lead battery according to the present invention is characterized in that, when the full charge determination means determines that the lead battery is fully charged, the integrated current value is returned to an initial value.

  The charge control device for a lead battery according to the present invention is fully satisfied when a current value corresponding to a share ratio of the lead battery to the power storage device when the power supply device is discharged at a high load becomes a predetermined threshold value or less. The determination of charging is stopped.

  The charge control device for a lead battery according to the present invention outputs a warning when the determination of the full charge is stopped.

  The charge control device for a lead battery according to the present invention is characterized in that the current value according to the sharing ratio is calculated by averaging a plurality of current values.

  The charge control device for a lead battery according to the present invention calculates a voltage increase rate of the power supply device, and determines that the lead battery has become a charge polarization when the voltage increase rate decreases.

  In the present invention, when a power supply device is configured by connecting a lead battery and an electricity storage device having a lower internal resistance in parallel, the voltage of the lead battery at the time of charging is not instantaneously increased to the voltage supplied from the alternator. It was made by finding the phenomenon that the voltage increase rate changes before and after the fully charged state, and by detecting the voltage increase rate, it is highly accurate that the lead battery is fully charged. Can be determined. Thereby, when the lead battery is fully charged, the drive energy of the alternator can be reduced by reducing the power generation voltage of the alternator.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a charge control device for a lead battery according to an embodiment of the present invention.

  As shown in FIG. 1, the lead battery 11 and the LIC 12 constitute a power supply device 13, and this power supply device 13 is mounted on the vehicle. The positive electrodes of the lead battery 11 and the LIC 12 are connected to each other by the power supply cable 14, and the negative electrodes of the lead battery 11 and the LIC 12 are connected to each other by the power supply cable 15. The lead battery 11 and the LIC 12 are connected in parallel. An alternator 17 driven by the engine 16 is mounted on the vehicle. The vehicle is driven by the engine 16 and the alternator 17 is driven, and the alternator 17 generates power. Electric power from the alternator 17 is supplied to the power supply device 13 so that the lead battery 11 and the LIC 12 are charged, and also supplied to an electric device 18 such as a starter, a spark plug, and lamps. The alternator 17 can also collect regenerative energy and generate electric power when the vehicle decelerates.

  The power supply cable 14 is provided with a current detector 21 for monitoring the current flowing through the lead battery 11, and the cable 22 connected between the positive electrode and the negative electrode of the power supply device 13 is monitored for the voltage of the power supply device 13. In order to do this, a voltage detector 23 is provided. Detection signals from the current detector 21 and the voltage detector 23 are sent to the engine control unit 24 for controlling the operation of the engine 16, and a voltage instruction signal is sent from the engine control unit 24 to the alternator 17. It is like that. A signal from a temperature detector that detects the temperatures of the lead battery 11 and the LIC 12 is also sent to the engine control unit 24. The engine control unit 24 includes a microprocessor CPU that performs arithmetic processing based on a detection signal from the current detector 21 and the like, a ROM that stores control programs, arithmetic expressions, map data, and a RAM that temporarily stores data. have. The engine control unit 24 calculates a current integrated value based on the detection signal of the current detector 21, determines whether the lead battery 11 is in a charged state or a discharged state, and detects from the voltage detector 23. A function of determining whether or not the lead battery 11 is fully charged based on the signal.

  As shown in FIG. 1, when a power supply device 13 using a lead battery 11 and a LIC 12 in combination is mounted on a vehicle, the power supply device 13 includes the lead battery 11. Even if it is a low case, electric power will be supplied with respect to the lead battery 11 from LIC12 with low internal resistance, and the charge amount fall of the lead battery 11 can be suppressed. On the other hand, when the engine is started by driving the starter motor, the lead battery 11 and the LIC 12 share the power to the starter motor. The sharing ratio between the LIC 12 and the lead battery 11 at the start of the engine is almost dependent on the temperature. However, since the LIC 12 has a low internal resistance and a lower output density than the lead battery 11, the LIC 12 is discharged from the LIC 12 at the start. Become. Thereby, while the fall of the remaining capacity of the lead battery 11 at the time of engine starting can be suppressed, the capacity | capacitance of the lead battery 11 can be made small.

  When the engine 16 is driven, the alternator 17 is driven, so that the electric power generated by the alternator 17 is supplied to an electric device 18 such as a spark plug and lamps and the power supply device 13 is charged. If the lead battery 11 can be charged in a state close to full charge, the energy efficiency of the charge is increased.

  Since the current detector 21 shown in FIG. 1 monitors the current of the lead battery 11, whether the battery is in a discharged state by determining the life of the lead battery 11 based on the signal from the current detector 21 and calculating the current integrated value Ah. Whether the battery is in a charged state can be determined. For example, since the current value of the lead battery 11 greatly decreases as the deterioration progresses, the threshold value is determined based on the sharing ratio data measured for each temperature of the new lead battery 11 in advance. When the threshold value is exceeded, the life of the lead battery 11 is determined. When the current integrated value Ah changes from discharging to charging and becomes a positive value, it can be determined from the signal from the current detector 21 that the charging state has been reached.

  FIG. 2A is a diagram showing the voltage change characteristic of a lead battery when the alternator 17 charges the lead battery 11 alone with a constant voltage near the target voltage 14.4V when only the lead battery 11 is mounted on the vehicle. It is. As shown in FIG. 2A, when the open circuit voltage is about 12.8 V and the remaining capacity SOC of the lead battery 11 is about 95%, the lead battery 11 instantaneously rises to the target voltage. In the process of charging the lead battery 11 from the discharged state to full charge, charge polarization occurs near 13.5V. When charge polarization occurs, energy loss occurs. However, since the power generation capacity of the alternator 17 is large, when the lead battery 11 is charged alone, a voltage fixing phenomenon in the vicinity of 13.5 V cannot be captured.

  FIG. 2B is a diagram showing voltage change characteristics of the LIC 12 when the LIC 12 alone is charged with a constant voltage near the target voltage of 14.4 V by the alternator 17 when only the LIC 12 is mounted on the vehicle. Since the internal resistance of the LIC 12 is lower than that of the lead battery 11, as shown in FIG. 2B, the amount of charge changes with time and the voltage does not instantaneously increase to the target voltage 14.4V of the alternator 17, At the same time, the voltage changes.

  FIG. 2C shows a power supply when the power supply device 13 formed by connecting the lead battery 11 and the LIC 12 in parallel as shown in FIG. 1 is charged with a constant voltage near the target voltage of 14.4 V by the alternator 17. FIG. 6 is a diagram showing voltage change characteristics of the device 13. This voltage change characteristic can be determined based on a monitoring signal from the voltage detector 23. As shown in FIG. 2C, when the power supply device 13 is charged with the target voltage of 14.4 V under the open voltage of 12.8 V, the voltage change is at the voltage A point near 13.5 V and the voltage A. An inflection point of the voltage increase rate (ΔV) was found at a higher point B. The voltage increase rate (ΔV2) from the point A voltage to the point B voltage is smaller than the voltage increase rate (ΔV1) from the start of charging until the point A voltage is reached. This is because the charge polarization of the lead battery 11 occurs at the point A, and after the charge polarization occurs, the charge energy is used for the chemical reaction of the electrolyte and the voltage increase rate decreases.

  When the lead battery 11 is fully charged, the voltage of the power supply device 13 becomes the voltage at the point B, and the voltage increase rate (ΔV3) in the process of rising to a voltage higher than that is the voltage in the process in which the charge polarization occurs. The increase rate is higher than the increase rate (ΔV2). Thus, the voltage increase rate (ΔV3) after point B is high because only the LIC 12 is charged, and this voltage increase rate approximates the increase rate during charging of the LIC alone. Yes.

  In this way, when the power supply device 13 in which the lead battery 11 and the LIC 12 are connected in parallel is charged by the alternator 17 at a constant voltage of the target voltage 14.4V, the voltage is increased in the process from the start of charging the power supply device 13 to the arrival of the target voltage. Since the increase rate changes, it is possible to detect that the lead battery 11 is fully charged by calculating the increase rate. By detecting the full charge of the lead battery 11, the power generation voltage of the alternator 17 can be reduced, and the lead battery 11 can be prevented from being overcharged and the power generation energy can be reduced.

  3 and 4 are flowcharts showing an algorithm for charge control of the lead battery. As shown in FIG. 3, when the starter motor is driven and the engine is started (step S1), the current I of the lead battery 11 is detected in step S2. The starter motor is a high-load electric device, and is discharged from the power supply device 13 at a high rate when it is driven. The high load current consumption of the starter motor is known, and power is supplied from the power supply device 13 to the starter motor by sharing the lead battery 11 and the LIC 12 at a sharing ratio substantially depending on temperature. When the lead battery 11 deteriorates, the current I of the lead battery 11 greatly decreases according to the share ratio of the lead battery 11 to the LIC 12, and the burden on the LIC 12 increases. For this reason, a threshold value is set for the current value flowing through the lead battery 11 based on the preset share ratio for each temperature, and the lead current 11 when the current I flowing through the lead battery 11 is greater than or equal to a predetermined value. Step S3 is executed to determine whether or not the battery 11 is fully charged. When the battery 11 is below a predetermined value, it is determined that the lead battery 11 is at the end of its life and the determination of full charge is stopped in step S4. When the determination of full charge is stopped, a warning is output in step S5. The warning is performed by turning on an alarm lamp or operating an alarm buzzer. The value of the current I for comparison with the threshold value in step S2 can be obtained by averaging the current values detected a plurality of times, thereby improving the reliability of stopping the full charge determination.

  When the engine is started and step S3 is executed, an integrated value (Ah) of the current flowing through the lead battery 11 is calculated by a signal from the current detector 21. In step S6, it is determined whether or not the integrated current value (Ah) has become a positive value (Ah> 0). If it is determined that the current value has changed from charging to charging in step S7, the voltage detector 23 is determined. The voltage signal from is read and the voltage of the power supply device 13 is detected. In step S8, the target generated voltage generated by the alternator 17 is calculated, and in step S9, the voltage increase rate (ΔV) is calculated. The voltage increase rate (ΔV) is calculated by obtaining a difference per unit time between the target power generation voltage (14.4 V) and the voltage V of the power supply device 13. However, if the process proceeds to discharging in the process of steps S7 to S9 (Ah <0), the process returns to step S3.

  In step S10 shown in FIG. 4, it is determined whether or not the voltage increase rate (ΔV) is higher than the reference value (ΔVa) (ΔV> ΔVa). In S11, the difference between the current voltage value (V0) of the power supply device 13 and the target power generation voltage (Vmax) of the alternator 17 is calculated, and whether or not the difference is equal to or less than the threshold value Va (Vmax−V0 ≦ Va). Determined. Further, in step S12, it is determined whether or not the current of the lead battery 11, that is, the leakage current I is equal to or less than the threshold value Ia (I0 <Ia). If YES is determined in these steps S10 to S12, it is determined in step S13 that the lead battery 11 is fully charged.

  The fact that the voltage increase rate (ΔV) is determined to be higher than the reference value (ΔVa) in step S10 corresponds to the time when point B, which is fully charged in FIG. It is obtained by comparing the reference value (ΔVa) stored in the ROM of the control unit 24 with the voltage increase rate (ΔV). At this time, as shown in FIG. 2C, the difference between the target power generation voltage (Vmax, 14.4 V, for example) of the alternator 17 and the voltage at the point B is equal to or less than the threshold value (Va). Step S11 is executed to prevent erroneous determination of charge determination. Similarly, when the lead battery 11 is fully charged, the current of the lead battery 11, that is, the leakage current is also less than or equal to a threshold value (Ia) that is almost zero. Step S12 is executed. The threshold values Va and Ia are set to a voltage value and a current value when the point B is slightly exceeded. However, full charge may be determined only by step S10.

  When it is determined in step S13 that the lead battery 11 is fully charged, step S14 is executed to clear the current integrated value (Ah) and return to the initial state. The determination that the lead battery 11 is fully charged is held until it is determined in step S15 that the lead battery 11 has started discharging. If it is determined in step S15 that the discharge has started, the process returns to step S3 to start calculating the current integrated value (Ah).

  When it is determined in step S13 that the lead battery 11 is in a fully charged state, a control signal is sent from the engine control unit 24 to the alternator 17 to control the generated voltage. Thus, the generation voltage can be reduced by determining the full charge of the lead battery 11, and the driving energy of the alternator 17 can be reduced to improve the fuel efficiency of the engine.

  FIG. 5 is measurement data showing an example of a full charge determination result of the lead battery when the vehicle equipped with the lead battery charge control device of the present invention travels in 10 modes. The vehicle was run under the driving conditions of Mode 1 to Mode 10. Mode 1 is idling after starting the engine, Mode 2 is acceleration from start to 20 km / h, Mode 3 is constant speed at 20 km / h, Mode 4 is deceleration from 20 km / h to stop, and Mode 5 is idling State. Furthermore, mode 6 is accelerated from the start to 40 km / h, mode 7 is constant speed at 40 km / h, mode 8 is decelerated from 40 km / h to 20 km / h, and mode 9 is accelerated from 20 km / h to 40 km / h. Mode 10 is decelerating traveling from 40 km / h to stopping.

  As shown in FIG. 5, when the starter motor is operated to start the engine, the lead battery 11 and the LIC 12 are discharged, and power is supplied to the starter motor. Until the starter motor is started and the alternator 17 is driven, the LIC 12 is discharged all at once, the discharge amount from the LIC 12 decreases, the discharge amount from the lead battery 11 increases, and the voltage of the power supply device 13 gradually decreases. . When the alternator 17 is driven by the engine 16, the lead battery 11 and the LIC 12 are charged. In FIG. 5, when the full charge flag is on, the lead battery 11 is fully charged. At this time, a control signal is sent to the alternator 17 so as to reduce the amount of power generated by the alternator 17. Since the alternator 17 can recover the regenerative energy by driving the alternator 17 with driving wheels when decelerating the vehicle, the alternator 17 increases the amount of power generation during deceleration.

  FIG. 6 is measurement data showing an example of a full charge determination result of the lead battery when the vehicle equipped with the lead battery charge control device of the present invention is driven in 15 modes. Mode 1 is idling after the engine is started, Mode 2 is acceleration running from start to 50 km / h, Mode 3 is constant speed running at 50 km / h, Mode 4 is decelerating from 50 km / h to 40 km / h, Mode 5 is a constant speed run at 40 km / h. Furthermore, mode 6 is accelerated from 40 km / h to 60 km / h, mode 7 is constant speed at 60 km / h, mode 8 is accelerated from 60 km / h to 70 km / h, mode 9 is constant speed at 70 km / h, Mode 10 is decelerating from 70 km / h to 50 km / h. Mode 11 is constant speed travel at 50 km / h, mode 12 is acceleration travel from 50 km / h to 70 km / h, mode 13 is constant speed travel at 70 km / h, mode 14 is deceleration travel from 70 km / h to stop, mode Reference numeral 15 denotes an idling state.

  As shown in FIG. 6, when the full charge of the lead battery 11 is determined and the full charge flag is turned on even when running in the 15 mode, the alternator 17 receives a control signal so as to reduce the power generation amount. The drive energy of the alternator 17 can be reduced by being sent. Even when the lead battery 11 is fully charged, as shown in FIG. 6, when the operation of the alternator 17 is controlled during deceleration traveling, regenerative energy is recovered and the LIC 12 is charged.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, although the power supply device 13 of the present invention is formed by the lead battery 11 and the LIC 12, if the power storage device has an internal resistance smaller than that of the lead battery 11, use a power storage device other than the lithium ion capacitor 12. Also good.

It is a block diagram which shows the charge control apparatus of the lead battery which is one embodiment of this invention. (A) is a diagram which shows the voltage change characteristic of the lead battery when it charges with respect to the lead battery single-piece | unit at the time of mounting only a lead battery in a vehicle, (B) is in the case where only LIC is mounted in a vehicle. It is a diagram which shows the voltage change characteristic of LIC when it charges with respect to the LIC single-piece | unit, (C) is a diagram which shows the voltage change characteristic of the power supply device when it charges with respect to the power supply device of this invention. It is a flowchart which shows the algorithm of charge control of a lead battery. It is a flowchart which shows the algorithm of charge control of a lead battery. It is measurement data which shows an example of the full charge determination result of a lead battery when driving a vehicle equipped with a charge control device for a lead battery of the present invention in 10 modes. It is measurement data which shows an example of the full charge determination result of a lead battery when driving | running | working 15 modes of the vehicle carrying the charge control apparatus of the lead battery of this invention.

Explanation of symbols

11 Lead battery 12 LIC (Lithium ion capacitor power storage device)
13 Power supply device 16 Engine 17 Alternator 21 Current detector (current detection means)
23 Voltage detector (voltage detection means)
24 Engine control unit (current integration means, full charge judgment means)

Claims (7)

A power supply device having a lead battery and an electricity storage device having an internal resistance smaller than that of the lead battery and connected in parallel to the lead battery;
An alternator driven by an engine and supplying power to the power supply device;
Current detection means for monitoring the current of the lead battery;
Voltage detection means for monitoring the voltage of the power supply device;
Current integrated value calculating means for calculating a current integrated value based on a signal from the current detecting means;
Based on a signal from the voltage detection means under a state where the current integrated value is a positive value, the voltage increase rate of the power supply device during the operation of the alternator is calculated, and the voltage increase rate is higher than a reference value. Get higher ,
When the difference between the current voltage value of the power supply device calculated based on the signal from the voltage detection means and the target power generation voltage of the alternator is equal to or less than a threshold value,
A charge control device for a lead battery, comprising: full charge determination means for determining that the lead battery is fully charged. In charge control device of the lead battery according to claim 1 Symbol placement, when the current value of the lead battery is calculated based on a signal from said current detecting means is equal to or less than the threshold value, the lead battery becomes fully charged A charge control device for a lead battery, wherein 3. The lead battery charge control device according to claim 1 or 2, wherein when the lead battery is determined to be fully charged by the full charge determination means, the current integrated value is returned to an initial value. Battery charge control device. The charge control device for a lead battery according to any one of claims 1 to 3 , wherein a current value according to a sharing ratio of the lead battery to the power storage device when the power supply device is discharged at a high load is predetermined. A charge control device for a lead battery, wherein the determination of full charge is stopped when the threshold value becomes equal to or less than the threshold value. 5. The lead battery charge control apparatus according to claim 4 , wherein a warning is output when the determination of the full charge is stopped. In charge control device of the lead battery according to claim 4, current value corresponding to the distribution ratio is the charge control device of the lead battery, characterized in that calculated by averaging a plurality of current values. The charge control device for a lead battery according to any one of claims 1 to 6 , wherein a voltage increase rate of the power supply device is calculated, and the lead battery becomes charge polarization when the voltage increase rate decreases. A charge control device for a lead battery.

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