JP2010011619A - Charging control method and charge controller of battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging control method of a battery for hybrid vehicle which can maintain the battery performance for a long term while bringing out the characteristics of the battery fully at run time by avoiding elevation of internal pressure resulting from generation of gas. <P>SOLUTION: When a section 14a for determining elevation of internal pressure determines that the internal pressure of at least one of a plurality of cells 110 included in a battery 11 for hybrid vehicle exceeded a predetermined value, the charging voltage or charging current of the battery 11 is reduced based on control by a battery control section 15 and an EV control section 23. Furthermore, a receiving section 31 actuates a buzzer 32 to notify the fact to the operator, or the like, with sound. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charge control method and a charge control device for a hybrid vehicle battery, and more particularly, to a charge control method for easily and efficiently reducing the influence of an increase in internal pressure of a plurality of cells (storage batteries) included in the battery. .

  Demand for alkaline storage batteries such as nickel metal hydride storage batteries is expanding mainly in industrial applications such as hybrid vehicles (hereinafter referred to as “HEV”) and emergency power supplies. In particular, an alkaline storage battery used as a main power source in HEV performs both driving (discharging) of the motor and storage (charging) of regenerative power from the generator, so charging / discharging is monitored / charged according to the state of charge (SOC) of the battery. Be controlled.

  On the other hand, in the alkaline storage battery, the amount of gas generated from the electrolyte rapidly increases at the end of charging, so that the internal pressure rises due to so-called “gas generation”, and the performance of the storage battery deteriorates. In order to reduce the influence on the storage battery due to the increase in internal pressure, several methods have been proposed.

  As one method, there is a method in which it is estimated that an increase in internal pressure due to gas generation occurs when the voltage between terminals of the alkaline storage battery exceeds a predetermined gas generation voltage, power generation is stopped for 5 seconds, and then power generation is restarted. However, in this method, a so-called hunting phenomenon occurs, and there is a problem that an unpleasant feeling is given to the HEV passenger.

As another method, there is a method for controlling the SOC by estimating the gas generation voltage from the voltage between the terminals of the storage battery or directly detecting the gas pressure with a gas sensor as described in Patent Document 1. Specifically, this is a control method for stopping charging when a valve provided in the storage battery is activated due to an increase in internal pressure.
JP-A-10-201209

  The method described in Patent Document 1 can avoid performance degradation of the storage battery due to an increase in internal pressure to some extent. However, in the state where the storage battery is mounted on the HEV, there is a high possibility that the internal pressure will repeatedly increase and the deterioration of the storage battery will be promoted. .

  The present invention has been made in view of the above-described problems, and avoids an increase in internal pressure due to gas generation, and a battery charge control method for a battery for HEV that can maintain the battery performance for a long time while sufficiently extracting the battery performance during traveling. The purpose is to provide.

In order to achieve the above object, a battery charge control method according to the present invention comprises: a motor that drives a vehicle; a generator that generates power by being driven by an engine; and supplies power to the motor via an inverter; A battery charge control method in a hybrid vehicle having a battery that accepts electric power from a generator as a charging current through the inverter,
Reducing the charging voltage or charging current of the battery when it is determined that the internal pressure of at least one of the cells included in the battery exceeds a predetermined value;
A step of notifying by voice that the internal pressure of at least one of the plurality of cells has exceeded a predetermined value.

  Here, it is preferable that the charging voltage of the battery is reduced by reducing the output voltage of the inverter, or the charging current of the battery is reduced by releasing a part of the direct current output from the inverter.

  Further, it is preferable that when the voltage between the terminals of the battery exceeds a predetermined value, it is determined that the internal pressure of at least one of the plurality of cells exceeds a predetermined value.

  However, when any one of the valves provided in each of the plurality of cells operates, it may be determined that the internal pressure of at least one of the plurality of cells has exceeded a predetermined value. Alternatively, when the degree of deformation of the container storing the plurality of cells exceeds a predetermined value, it may be determined that the internal pressure of at least one of the plurality of cells exceeds a predetermined value.

  The battery charge control method according to the present invention preferably further includes a step of removing, from the battery, a cell having deteriorated characteristics among the plurality of cells.

Further, the battery charge control device according to the present invention includes:
A motor that drives a vehicle; a generator that is driven by an engine to generate electric power; and a battery that supplies electric power to the motor via an inverter and receives electric power from the generator as a charging current via the inverter. A charge control device for a battery used in a hybrid vehicle having:
An internal pressure increase determination unit that determines whether or not the internal pressure of at least one of the cells included in the battery exceeds a predetermined value;
A control unit for controlling a charging voltage or a charging current of the battery based on an output signal of the internal pressure increase determination unit;
A sound generation unit that generates sound based on an output signal of the internal pressure increase determination unit is provided.

  The battery charge control device according to the present invention is preferably provided in the navigation system, and further includes a receiving unit that receives an output signal of the internal pressure increase determination unit and transfers the output signal to the control unit.

  According to the present invention, in a battery for HEV, a charge control method that can prevent a rise in internal pressure due to gas generation, sufficiently bring out the performance of the battery during traveling, and satisfy the requirements for battery durability. Can provide.

  Hereinafter, a method for controlling charging of an HEV battery according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of an HEV that employs the charge control method according to the present invention.

  The HEV basically includes a power supply system 1 and a vehicle drive system 2. The power supply system 1 includes a battery 11, an inverter 12, a bypass circuit 13, an internal pressure increase determination unit 14a, a battery control unit 15, a reception unit 31, and a buzzer 32. On the other hand, the vehicle drive system 2 includes a motor generator 21, an engine 22, and an EV control unit 23. The battery control unit 15 of the power supply system 1 and the EV control unit 23 of the vehicle drive system 2 control HEV in cooperation.

  First, the HEV operation will be briefly described with a focus on the vehicle drive system 2. The motor generator 21 has functions of both a motor and a generator. The vehicle is driven by the motor generator 21, and the engine 22 generates power from the generator of the motor generator 21.

  The EV control unit 23 determines a torque command based on information such as the accelerator opening of the HEV, the brake depression amount, and the vehicle speed, and performs control so that the output of the motor generator 21 matches the torque command. That is, the EV control unit 23 controls switching in the inverter 12 and controls the output of the engine 22. Thereby, the input to the motor generator 21 is determined, and the output of the motor generator 21 is controlled to match the torque command.

  When the output of the engine 22 is larger than the output of the motor generator 21, electric power is output from the inverter 12 toward the battery 11, and the battery 11 is charged. On the other hand, when the output of engine 22 is smaller than the output of motor generator 21, electric power is supplied from inverter 12 to motor generator 21, and battery 11 is discharged.

  Next, the function of each component of the power supply system 1 will be specifically described. The battery 11 as the main power source is configured by connecting a large number of cells 110 made of an alkaline storage battery or a lithium secondary battery in parallel and / or in series. The voltage Vb1 between the terminals of the battery 11 is detected by the voltage sensor 16 and supplied to the internal pressure increase determination unit 14a.

  FIG. 2A shows the configuration of the internal pressure increase determination unit 14a. The voltage value Vb1 input to the internal pressure increase determination unit 14a is compared with a preset reference voltage Vs1 by the voltage comparison unit 141. When the voltage value Vb1 exceeds the reference voltage Vs1, the voltage comparison unit 141 determines that the internal pressure of the cell 110 has exceeded a predetermined value, and outputs a determination signal Cp. The output determination signal Cp is transmitted to the receiving unit 31.

  A current sensor 17 is connected in series to the battery 11, and the current value Ib detected by the current sensor 17 is supplied to the battery control unit 15. The battery control unit 15 calculates the SOC of the battery 11 based on the current value Ib.

  The battery control unit 15 indirectly controls the operation of the inverter 12 through the EV control unit 23 based on the determination signal Cp transmitted from the internal pressure increase determination unit 14 a through the reception unit 31. A storage unit 18 is connected to the battery control unit 15, and conditions for charging the battery 11 are stored in the storage unit 18.

  The inverter 12 converts an alternating current generated by the motor generator 21 into a direct current for charging the battery 11 in accordance with the control signal Ci of the EV control unit 23. Similarly, the inverter 12 converts the current output from the battery 11 into alternating current having a frequency corresponding to the rotational speed of the motor generator 21.

  The bypass circuit 13 changes the charging condition of the battery 11 by releasing a part of the charging current to the battery 11 according to the control signal Cb of the battery control unit 15. The method of changing the battery charging condition by the bypass circuit 13 is easier to control than the method of changing the rotational speed of the motor described in Patent Document 1. In addition, efficient energy utilization is achieved by supplying the escaped current to a capacitor or storage battery (not shown).

  The receiving unit 31 receives the determination signal Cp from the internal pressure increase determination unit 14 a and transfers it to the battery control unit 15. In addition, a buzzer 32 that functions as a sound generator is connected to the receiver 31. The buzzer 32 includes a piezoelectric element, and outputs a sound when the receiving unit 31 receives the determination signal Cp to notify the HEV driver or passenger that the internal pressure of the cell 110 has exceeded a predetermined value.

  The receiving unit 31 and the buzzer 32 are provided in the navigation system 3 mounted in the HEV. Normally, since the navigation system 3 is powered on during HEV operation, the receiving unit 31 and the buzzer 32 operate normally, and the charging control according to the present invention is performed. Therefore, during the HEV operation, the driver or passenger notices that the internal pressure of the cell 110 has increased by voice, and has the effect of prompting the inspection of the battery after the operation is completed, so it is very effective for HEV maintenance. It is.

  In the present embodiment, inverter 12, bypass circuit 13, internal pressure increase determination unit 14a, battery control unit 15, EV control unit 23, reception unit 31, and buzzer 32 constitute a charge control device of the present invention. Further, the inverter 12, the bypass circuit, the battery control unit 15 and the EV control unit 23 constitute a control unit of the present invention.

  Next, the charge control method according to the present invention will be described in detail with reference to FIG. The battery control unit 15 obtains the SOC value by integrating the current value Ib detected by the current sensor 17, and performs charging control while comparing this value with the charging condition stored in the storage unit 18. Under the initially set conditions, an increase in internal pressure due to gas generation should not occur, but in reality, an increase in internal pressure due to gas generation may occur due to variations in the cells 110.

  In the conventional control method described above, a gas sensor is built in each cell 110 of the battery 11 to directly detect the gas pressure. On the other hand, in the present embodiment, when the inter-terminal voltage Vb1 of the battery 11 detected by the voltage sensor 16 exceeds the reference value Vs1 (see FIG. 2A), the internal pressure increase due to gas generation in the internal pressure increase determination unit 14a. The determination signal Cp is transmitted to the battery control unit 15 via the reception unit 31.

  The battery control unit 15 that has received the determination signal Cp changes the method of charge control. Specifically, the set voltage is changed or the charging current value is changed. The set voltage can be changed at any time using the inverter 12. Further, the charging current value can be changed by allowing a predetermined current amount to escape to the capacitor or the like by the bypass circuit 13.

  Further, the receiving unit 31 that has received the determination signal Cp operates the buzzer 32 to notify the driver and passengers that the internal pressure of the cell 110 has increased. The driver or the like can request that the battery 11 be inspected by a maintenance shop or the like because the buzzer 32 indicates that the internal pressure has increased. As a result of the inspection, if there is a cell 110 (for example, less than 2 Ah) whose performance is deteriorated and the discharge capacity is extremely reduced, it is replaced with a cell having an appropriate discharge capacity.

  As explained above, the internal pressure rise due to gas generation is detected at an early stage, the charging control method is changed based on the result, and a battery inspection is requested to a maintenance shop etc., and the cell is replaced when necessary. As a result, the performance of the entire battery can be maintained for a long time. ADVANTAGE OF THE INVENTION According to this invention, the power supply system which suppresses degradation by the internal pressure rise by gas generation can be embodied with a simple structure, and the safety | security and reliability of HEV improve.

  In the present embodiment, the increase in the internal pressure of the cell 110 is determined by detecting the voltage value Vb between the terminals of the battery 11, but the determination method for the increase in the internal pressure is not limited to this. 2B and 2C show other configuration examples of the internal pressure increase determination unit.

  FIG. 2B shows a configuration of an internal pressure increase determination unit 14b that receives a signal Sb from a valve provided in the cell 110 and determines an increase in internal pressure. Each cell 110 is provided with a valve. When the internal pressure rises and the valve of the cell 110 is opened, a signal Sb is output from the valve, and the signal Sb is received by the valve operation detecting means 142. When receiving the signal Sb from any of the cells 110, the valve operation detection unit 142 determines that the internal pressure of the cell 110 has increased, and outputs the signal Cp.

  FIG. 2C shows a configuration of an internal pressure increase determination unit 14c that detects the increase in internal pressure by detecting the deformation of the cell accompanying expansion when the metal case of the cell 110 is expanded by the internal pressure. Specifically, a strain sensor is attached to a container that stores a plurality of cells 110 (not shown), and a signal Vb2 output from the strain sensor is compared with a reference value Vs2 by a voltage comparison unit 143. When the metal case of the cell 110 expands due to the increase in internal pressure, the container deforms and the output Vb2 of the strain sensor exceeds the reference value Vs2, the voltage comparison means 143 determines that the internal pressure of the cell 110 has increased, and the signal Cp Is output.

  Since the gas sensor used for detecting the internal pressure in the conventional power supply system is expensive, the cost of the power supply system is increased. On the other hand, since the voltage sensor, valve, and strain sensor used in this embodiment are inexpensive, the cost of the power supply system can be suppressed.

  In the present embodiment, the increase in the internal pressure of the cell 110 is notified to the HEV driver or the like by the buzzer 32 using a piezoelectric element, but the present invention is not limited to this. Various voice generating means can be used as long as it can notify the driver or the like by voice that the internal pressure of the cell 110 has increased during the HEV operation.

  Examples of the present invention and comparative examples will be described below. Needless to say, the present invention is not limited to this embodiment. In this example, a nickel metal hydride storage battery was used as the battery 11 constituting the main power source.

Example 1
First, a method for manufacturing the battery 11 will be described. Winding in a state of sandwiching a separator made of a woven polypropylene nonwoven fabric between a long positive electrode using nickel hydroxide as an active material and a long negative electrode using a hydrogen storage alloy as an active material, An electrode group was constructed. This electrode group is inserted into a cylindrical battery case having an inner diameter of 30 mm and a length of 60 mm, and an electrolyte mainly composed of potassium hydroxide is injected, then the opening of the battery case is sealed, and nickel having a nominal capacity of 6 Ah A hydrogen storage battery was obtained. This nickel metal hydride storage battery was connected in series in 12 cells to form a main power source (battery 11).

  Using the battery 11 described above, as shown in FIG. 1, the inverter 12 is controlled by the control signal Ci from the EV control unit 23, so that the battery 11 is discharged as a current value 30A until reaching a voltage of SOC 20%. Thereafter, the battery was charged until a voltage of SOC 80% was reached.

  The voltage of SOC 20% and the voltage of SOC 80% here are initial values, and are the total values of the voltages across the terminals of the 12 cells 110 connected in series. When it is determined that the inter-terminal voltage of the battery 11 exceeds a predetermined value and the internal pressure of the cell 110 has increased, the receiving unit 31 installed in the navigation system receives the determination signal Cp from the internal pressure increase determination unit 14a, The internal pressure rise is displayed on the display panel of the navigation system. Furthermore, the battery control unit 15 that has received the determination signal Cp via the reception unit controls the inverter 12 via the EV control unit 23 to change the charging voltage of the battery 11. The power supply system 1 was charged and discharged for 10,000 cycles in an atmosphere at 45 ° C.

(Comparative Example 1)
The receiver 31 was not installed in the navigation system 3 and 10,000 charge / discharge cycles were performed. Otherwise, the configuration was the same as in Example 1.

(Example 2)
A buzzer 32 using a piezoelectric element was installed in the navigation system 3 and linked to the operation of the receiver 31. That is, when the internal pressure increase determination unit 14a detects that the inter-terminal voltage Vb1 of the battery 11 exceeds a predetermined value (reference value Vs1) and outputs the determination signal Cp, and the reception unit 31 receives the signal Cp. The buzzer 32 sounded. The configuration was the same as in Example 1 except that the battery 11 was checked when the buzzer 32 sounded.

(Comparative Example 2)
The configuration was the same as in Example 2 except that the buzzer 32 using a piezoelectric element was not installed in the navigation system 3 and the battery 11 was not inspected.

(Example 3)
As an internal pressure increase determination unit, the internal pressure increase determination unit 14b illustrated in FIG. 2B was used. In addition, a buzzer 32 using a piezoelectric element was installed in the navigation system 3, and the buzzer 32 was sounded when the receiving unit 31 received a signal Cp notifying that the internal pressure of the cell 110 had increased, and the battery 11 was inspected at that time. Otherwise, the configuration was the same as in Example 1.

(Comparative Example 3)
The configuration was the same as that of Example 3 except that the buzzer 32 by the piezoelectric element was not installed in the navigation system 3 and the battery 11 was not inspected.

Example 4
As the means for estimating the internal pressure increase, the internal pressure increase determination unit 14c shown in FIG. 2C was used. Further, a buzzer 32 using a piezoelectric element was installed in the navigation system 3, and the buzzer 32 was sounded when the receiving unit 31 received a signal Cp notifying that the internal pressure of the cell 110 had increased. The configuration was the same as in Example 1 except that the battery was checked when the buzzer 32 sounded.

(Comparative Example 4)
The configuration was the same as in Example 4 except that the buzzer 32 made of piezoelectric elements was not installed in the navigation system 3 and the battery was not inspected.

<Internal pressure rise>
About each said Example and comparative example, the internal pressure rise by gas generation | occurrence | production was evaluated in the following ways. That is, in order to determine the effect of suppressing the increase in internal pressure due to gas generation, a battery evaluation of 10,000 cycles was performed. The increase in internal pressure is induced by an imbalance in the battery characteristics of individual cells, and the gas generation potential changes. As a result, the capacity decreases and the battery deteriorates.

  100 test modules (batteries 11) were simultaneously tested, and the discharge capacity from the upper limit voltage at the end of charging every 2000 cycles to the lower limit voltage at the time of discharging was evaluated up to 10,000 cycles. When the discharge capacity of the test module is less than 2 Ah, deterioration due to an increase in internal pressure due to gas generation is “significant”, and when the discharge capacity is less than 2.0 to 3.0 Ah, deterioration due to an increase in internal pressure due to gas generation is “present”, 3.0 to Table 1 shows that deterioration of the internal pressure due to gas generation was “slightly” for those of less than 3.5 Ah, and deterioration due to increase of internal pressure due to gas generation was “no” for those of 3.5 Ah or more. Here, although there are variations in the test modules, the capacity value of the module having the largest number of 60 or more out of 100 (whole) was determined.

  As is clear from Table 1, all the test modules of Examples 1 to 4 maintain the performance of the entire assembled battery for a long time by detecting the internal pressure increase due to gas generation at an early stage, and checking and replacing the battery. I knew it was possible. On the other hand, in the test modules of Comparative Examples 1 to 4, when the number of charge / discharge cycles exceeded 8000 cycles, the discharge capacity was significantly reduced due to the increase in internal pressure.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply system which suppresses degradation by the internal pressure rise by gas generation with a simple structure can be actualized, As a result, the safety | security and reliability of HEV can be improved.

  The method for controlling charging of a battery for HEV according to the present invention has a great effect in use in tough use (HEV, household cogeneration, industrial) which is an advantage of an alkaline storage battery.

It is a figure which shows the structure of HEV which employ | adopted the charge control method of the battery concerning embodiment of this invention. It is a figure which shows the structural example of an internal pressure rise determination part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply system 2 Vehicle drive system 3 Navigation system 11 Battery 12 Inverter 13 Bypass circuit 14a-14c Internal pressure rise determination part 15 Battery control part 16 Voltage sensor 17 Current sensor 18 Memory | storage part 21 Motor generator 22 Engine 23 EV control part 24 Drive wheel 31 Receiver 32 Buzzer 110 cells

Claims (12)

A motor that drives the vehicle; a generator that is driven by an engine to generate electric power; and a battery that supplies electric power to the motor via an inverter and receives electric power from the generator as a charging current via the inverter. A charge control method for a battery in a hybrid vehicle having
Reducing the charging voltage or charging current of the battery when it is determined that the internal pressure of at least one of the cells included in the battery exceeds a predetermined value;
A battery charge control method comprising: notifying by voice that the internal pressure of at least one of the plurality of cells has exceeded a predetermined value.   The battery charging control method according to claim 1, wherein a charging voltage of the battery is reduced by reducing an output voltage of the inverter.   The battery charging control method according to claim 1, wherein a charging current of the battery is reduced by releasing a part of a direct current output from the inverter.   The battery charge control method according to claim 1, wherein when a voltage between the terminals of the battery exceeds a predetermined value, it is determined that an internal pressure of at least one of the plurality of cells exceeds a predetermined value.   The internal pressure of at least one cell among the plurality of cells is determined to have exceeded a predetermined value when any one of the valves provided in each of the plurality of cells is activated. Battery charge control method.   The determination according to claim 1, wherein when the degree of deformation of the container for storing the plurality of cells exceeds a predetermined value, it is determined that an internal pressure of at least one of the plurality of cells exceeds a predetermined value. Battery charge control method.   The battery charging control method according to claim 1, wherein the sound is a buzzer sound.   The battery charge control method according to claim 1, further comprising a step of removing a cell having deteriorated characteristics from the battery among the plurality of cells. A motor that drives the vehicle; a generator that is driven by an engine to generate electric power; and a battery that supplies electric power to the motor via an inverter and receives electric power from the generator as a charging current via the inverter. A battery charge control device used in a hybrid vehicle having
An internal pressure increase determination unit that determines whether or not the internal pressure of at least one of the cells included in the battery exceeds a predetermined value;
A control unit for controlling a charging voltage or a charging current of the battery based on an output signal of the internal pressure increase determination unit;
A battery charge control device comprising: a sound generation unit that generates sound based on an output signal of the internal pressure increase determination unit.   The battery charging control device according to claim 9, wherein the control unit controls a charging voltage of the battery by controlling an output voltage of the inverter.   The battery charging control device according to claim 9, wherein the control unit controls a charging current of the battery by releasing a part of a direct current output from the inverter.   The battery charging control device according to claim 9, further comprising a receiving unit that is provided in the navigation system and receives an output signal of the internal pressure increase determination unit and transfers the output signal to the control unit.

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