JP3687628B2 - Charge state detection system and automobile equipped with the system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection system for state of charging, capable of accurately detecting the state of charge of a battery. <P>SOLUTION: In this detection system for state of charging provided on an electric vehicle, it is determined whether a current value I flowing in a cell motor is equal to or larger than a prescribed current value (S310). If it is negative determination, the station of charge of the battery is calculated not from an internal resistance value r, because large the slope of a current characteristics curve deteriorates accuracy, but rather by utilizing the relation between the accurate internal resistance value r and the state of charge (S312), the state of charge of a lead battery is detected with high accuracy. In the electric vehicle of this embodiment, the engine is prevented from falling into start disabled state at the idling stop and start. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a charging state detection system and an electric vehicle, and more particularly, to a charging state detection system that calculates a charging state of a battery according to an internal resistance value and an electric vehicle including the charging state detection system.
[0002]
[Prior art]
In recent years, idling stop start (ISS) has been performed in order to cope with the reduction of exhaust gas by an engine vehicle, and a technique for keeping the engine vehicle in an idling stopable state is desired. The engine automobile includes a battery (storage battery) that supplies electric power to the cell motor for starting the engine via an ignition switch during ISS. Lead batteries are typical batteries that can be used for this type of application. At idle stop, the electrical load is provided by the battery. The state of charge (SOC) of the battery is always estimated (detected) in order to maintain the ISS state. The method of estimating the state of charge of the battery is disclosed a method, in Japanese Patent Laid-Open No. No. 6-150981 to obtain the internal resistance value and the differential internal resistance with a large current at the start of the engine (the inclination of the voltage-current straight line) Thus, there is a method of obtaining from a voltage-current straight line. When the state of charge of the battery estimated by these methods falls below a certain value, the battery is charged by starting the engine.
[0003]
[Problems to be solved by the invention]
However, in the above prior art, since the state of charge is not estimated in consideration of the operating state of the engine, the battery is charged when the state of charge of the battery falls below a certain value even though the engine is in a rotating state. When the engine is restarted (current is supplied to the cell motor), the engine is injured twice. Since the engine has already started, the current flowing to the cell motor in the case of twice is smaller than the current flowing when starting the engine. For example, a current of about 300 A flows from the battery when the engine is started, and a current of about 30 A flows through the cell motor when the engine is started twice.
[0004]
FIG. 6 shows the relationship between the internal resistance of the battery and the state of charge with respect to the current flowing through the cell motor. As shown in FIG. 6, the internal resistance and the charge state are different when the engine is started (when the current value flowing through the cell motor is 300 A) when the current is twice (when the current value flowing through the cell motor is 30 A). The slope of the current characteristic curve indicating the relationship increases. For this reason, when calculating the charge state of the battery from the internal resistance of the battery using the current characteristic at the time of twice, the charge state is calculated from the internal resistance using the current characteristic at the time of engine start with a small inclination It is difficult to accurately detect the state of charge of the battery as compared to the above, and there are cases where the engine cannot be started due to the power of the battery at the time of idling stop / start.
[0005]
An object of the present invention is to provide a state of charge detection system capable of accurately detecting a state of charge of a battery and an electric vehicle including the state of charge detection system.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, a first aspect of the present invention includes a determination unit that determines whether the current value flowing from the battery to the cell motor for engine start via the ignition switch is equal to or greater than a predetermined current value that allows engine start; Internal resistance calculation means for calculating the internal resistance value of the battery based on the current value flowing through the engine starting cell motor, and the internal resistance value of the battery determined in advance from the internal resistance value calculated by the internal resistance calculation means Charging state calculating means for calculating a charging state of the battery according to a correspondence relationship between the charging state and the charging state, and the charging state calculating means calculates the charging state of the battery when the determination by the determining means is affirmative. The battery state of charge is not calculated when the determination by the determination means is negative .
[0007]
In the first aspect, the internal resistance calculating means for calculating the internal resistance value of the battery based on the current value flowing through the engine starting cell motor, and the internal battery value determined in advance from the internal resistance value calculated by the internal resistance calculating means. Charge state calculation means for calculating the charge state of the battery according to the correspondence relationship between the resistance value and the charge state, and the value of the current flowing from the battery to the cell motor for engine start via the ignition switch by the determination means is determined or allowed to predetermined current value or more, is calculated state of charge of the battery when a positive determination is made at decision means by the charge state calculating means, the state of charge of the battery when a negative determination is not calculated. According to this aspect, if the state of charge is calculated from the internal resistance value of the battery when the determination of the state of charge is negative, the calculation accuracy of the state of charge of the battery is reduced, so that the state of charge is not calculated (calculation Since the calculation is performed using the relationship between the internal resistance value with high calculation accuracy when the determination means makes a positive determination and the charge state without using the relationship between the low accuracy internal resistance value and the charge state, The state of charge can be detected with high accuracy.
[0008]
Further, in order to solve the above problems, a second aspect of the present invention, a determination unit current or voltage value of the generator that generates electricity by the rotation of the engine or less than a predetermined value, the generator current An internal resistance calculation means for calculating an internal resistance value of the battery based on a value or a voltage value, and an internal resistance value of the battery and a state of charge determined in advance from the internal resistance value calculated by the internal resistance calculation means Charging state calculation means for calculating the state of charge of the battery according to the correspondence relationship, the charge state calculation means calculates the state of charge of the battery when the determination by the determination means is affirmative, and the determination means When the determination is negative, the state of charge of the battery is not calculated .
[0009]
In the second aspect, the internal resistance calculation means for calculating the internal resistance value of the battery based on the current value or voltage value of the generator, and the internal of the battery determined in advance from the internal resistance value calculated by the internal resistance calculation means Charging state calculation means for calculating the state of charge of the battery according to the correspondence relationship between the resistance value and the state of charge, and whether the current value or voltage value of the generator that generates electricity by engine rotation by the determination means is less than a predetermined value Is determined, and the battery state of charge is calculated when the battery state of charge is determined to be affirmative by the determining unit, and the battery state of charge is not calculated when a negative determination is made . According to this aspect, since the engine is stopped when the determination means makes an affirmative determination, the charge state calculation means uses the relationship between the internal resistance value with high calculation accuracy and the charge state to determine the charge state of the battery. When the calculation is made and the negative determination is made by the determination means, the engine is started, so the relationship between the internal resistance value and the charging state with low calculation accuracy is not used, so the charging state of the battery can be detected with high accuracy. it can.
[0010]
A third aspect of the present invention is an electric vehicle including the charge state detection system according to the first or second aspect. The electric vehicle of this aspect can detect the state of charge of the battery with high accuracy by the charge state detection system of the first or second aspect.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
A first embodiment in which the present invention is applied to an electric vehicle will be described below with reference to the drawings.
[0012]
<Configuration>
As shown in FIG. 1, an electric vehicle 20 of the present embodiment includes an engine that is a drive source of the electric vehicle 20, a cell motor that starts the engine, a generator that generates electric power with the driving force of the engine, and charges a lead battery. Charge state (SOC, State Of
Charge state detection system that calculates (Charge).
[0013]
The lead battery has a rectangular battery case that serves as a container for the lead battery. The battery case material is excellent in terms of moldability, electrical insulation, corrosion resistance and durability, for example, polymer resins such as acrylic butadiene styrene (ABS), polypropylene (PP), polyethylene (PE), etc. Can be selected. In addition, the battery case can be configured as a monoblock battery case in which a total of 18 cell chambers in 2 rows and 9 columns are defined and integrally formed by partition walls that partition the inside of the outer peripheral wall vertically and horizontally. Each cell chamber defined in the battery case accommodates one set of electrode plate groups (cells), and a total of 18 electrode plate groups are accommodated in the battery case. In each electrode plate group, six unformed negative electrode plates and five unformed positive electrode plates are laminated via a retainer (separator) made of glass fiber, and the nominal voltage (cell voltage) after formation (initial charge) is 2.0V. Therefore, the group voltage of the lead battery is 36V. The upper part of the battery case is bonded (or welded) to an upper lid made of a polymer resin such as ABS, PP or PE that seals the upper opening of the battery case. A rod-shaped positive external output terminal and a negative external output terminal for supplying electric power to the outside using a lead battery as a power source are erected on the upper lid at diagonal corners.
[0014]
As shown in FIG. 2, the state of charge detection system 11 has an ignition switch (hereinafter referred to as “IGN switch”) 9. The positive external output terminal of the lead battery 1 described above is connected to the central terminal of the IGN switch 9. The IGN switch 9 has an OFF terminal, an ON / ACC terminal, and a START terminal in addition to the central terminal, and the central terminal and any of these OFF, ON / ACC, and START terminals can be switched in a rotary manner. is there.
[0015]
The START terminal is connected to one end of the cell motor 3 via a current sensor 7 such as a Hall element. In the Hall element type current sensor, a gap is formed in the ring core, and the Hall element is inserted in the gap. When a through current flows through the ring core, the through current is proportional to the magnetic flux density generated in the gap, and the current value of the through current can be detected by measuring the voltage of the Hall element. The cell motor 3 can transmit a rotational driving force to the rotating shaft of the engine 4 via a clutch mechanism (not shown).
[0016]
The ON / ACC terminal is connected to one end of a generator 2 that generates electric power by rotation of the engine 4 via an auxiliary device 5 such as a lamp or a wiper and a diode that allows a current to flow in one direction. That is, the anode of the diode is connected to one end of the generator 2, and the cathode is connected to the ON / ACC terminal. The rotating shaft of the engine 4 can transmit power to the generator 2 via a clutch mechanism (not shown). For this reason, when the engine 4 is in a rotating state, the generator 2 is operated via a clutch mechanism (not shown), and the electric power from the generator 2 is supplied (charged) to the auxiliary machine 5 or the lead battery 1. Note that the OFF terminal is not connected to any of them.
[0017]
The output terminal of the current sensor 7 is connected to an A / D converter built in a microcomputer 8 (to be referred to as a microcomputer hereinafter). For this reason, the Hall voltage output from the current sensor 7 is converted into a digital value by the A / D converter, and the microcomputer 8 can capture the current value I flowing through the cell motor 3. The external output terminal of the lead battery 1 is connected to the A / D converter, and the output side of the A / D converter is connected to the microcomputer 8. For this reason, the microcomputer 8 can take in the voltage value V of the lead battery 1 as a digital value. The microcomputer 8 can communicate with the host vehicle-side microcomputer 10 via an interface.
[0018]
The microcomputer 8 is a CPU that functions as a central processing unit, a ROM that stores basic control programs and various setting values of the charging state detection system 11, a RAM that functions as a work area for the CPU and temporarily stores data. It is comprised including. Further, the other end of the generator 2, the cell motor 3 and the auxiliary machine 5, the negative external output terminal of the lead battery 1, and the microcomputer are each connected to the ground.
[0019]
<Operation>
Next, the operation of the charging state detection system 11 will be described with the CPU of the microcomputer 8 as a main component with reference to a flowchart. When the microcomputer 8 is turned on in the initial state, various set values stored in the ROM are transferred to the RAM, and the following charge state detection routine is executed.
[0020]
As shown in FIG. 3, in the charge state detection routine, first, in step 302, the current value I flowing through the cell motor 3 is captured. Next, in step 304, in order to determine whether or not the IGN switch 9 is at the position of the START terminal, it is determined whether or not the current value I is greater than or equal to a threshold value (for example, 0.1 (A)). If so, the process returns to step 302. If the determination is affirmative, the voltage value V of the lead battery 1 is captured in the next step 306.
[0021]
Next, in step 308, the internal resistance value r of the lead battery 1 is calculated from the acquired current value I and battery voltage value V. That is, when the IGN switch 9 is connected to the START terminal, the lead battery 1 having the internal resistance value r and the cell motor 3 having the resistance value R form a closed circuit. Therefore, a relational expression of current value I = voltage value V / (internal resistance value r of lead battery 1 + resistance value R of cell motor 3) is established. The resistance value R of the cell motor 3 and the current value I flowing through the cell motor 3 have a certain relationship as is well known. The CPU obtains the resistance value R from the current value I using the IR table in which the characteristics of the current value I and the resistance value R are tabulated, and the current value I, voltage value V, and The resistance value R is substituted to calculate the internal resistance value r.
[0022]
In step 310, in order to determine whether or not the engine 4 is being started, it is determined whether or not the current value I flowing through the cell motor 3 is equal to or greater than a predetermined current value (for example, 100 A) that allows the engine to start. In the next step 312, as shown in FIG. 6, the charge state of the lead battery 1 is obtained using the relationship between the internal resistance value r and the charge state with a small slope of the current characteristic curve and high accuracy. And the charge state detection routine ends. On the other hand, when a negative determination is made (at the time of 2 degrees), since the slope of the current characteristic curve is large (30A in FIG. 6) and the state of charge (SOC) is calculated from the internal resistance value r, the accuracy of the state of charge decreases. In order to calculate the internal resistance value and the state of charge of the battery with high accuracy without using (disabling) the current characteristic curve at the time of negative determination, the process returns to step 302.
[0023]
As described above, in the charging state detection system 11 mounted on the electric vehicle 20 according to the present embodiment, it is determined whether the current value I flowing through the cell motor 3 is 100 A or more (step 310). Since the slope of the curve is large, the relationship between the low-precision internal resistance value r and the state of charge (SOC) is invalidated without using it, and the state of charge of the battery is determined using the relationship between the high-precision internal resistance value r and the state of charge. (Step 312), the state of charge of the lead battery 1 can be detected with high accuracy. Therefore, in the electric vehicle according to the present embodiment, it is possible to prevent the engine from being unable to start at the time of idling stop / start.
[0024]
In the present embodiment, the charge state detection system 11 calculates the internal resistance value r of the lead battery 1 and then determines whether or not the engine is started. However, it is determined whether or not the engine is started. After that, the internal resistance value r may be calculated.
[0025]
Further, in the present embodiment, in order to determine whether or not the engine 4 is started by the charging state detection system 11, an example in which the predetermined current value allowing the engine start is 100A is shown. Needless to say, it is not limited and is changed according to the specifications of the cell motor 3.
[0026]
Furthermore, in the present embodiment, the IGN switch 9 having the center, OFF, ON / ACC, and START terminals is illustrated, but if the switch can be switched to at least the OFF, ON / ACC, and START terminals, The number of terminals is not limited, and an IGN switch in which an ON terminal and an ACC terminal are separated may be used.
[0027]
(Second Embodiment)
Next, a second embodiment in which the present invention is applied to an electric vehicle will be described. The charge state detection system of this embodiment determines whether or not the engine is starting from the current flowing through the generator 2. In the following embodiments, the same components and steps as those in the first embodiment are denoted by the same reference numerals, the description thereof is omitted, and only different portions will be described.
[0028]
As shown in FIG. 4, in the present embodiment, a current sensor 6 such as a Hall element is inserted between the diode and the generator 2 in the charging state detection system 12, and the current sensor shown in the first embodiment is shown. 7 is missing. The output terminal of the current sensor 6 is connected to the microcomputer 8. Therefore, in the present embodiment, CPU may incorporate a current value I _G flowing between the diodes and the generator 2, a current value I _G is less than a predetermined value (e.g., 0.1 A or less) or the determination By doing so, it is possible to determine whether or not the generator 2 is stopped, in other words, whether or not the engine is stopped (when starting).
[0029]
As shown in FIGS. 3 and 4, in the present embodiment, at step 310, to determine the operating state of the engine, the current value I _G flowing between the diodes and the generator 2 or 0.1A or less If the determination is affirmative (when the engine is stopped), the process proceeds to the next step 312. If the determination is negative, the process returns to step 302.
[0030]
As described above, in this embodiment of the electric vehicle in the mounted state of charge detection system 12, the current value I _G flowing between the diodes and the generator 2 determines whether 0.1A or less (engine stopped) (Step 310) When the negative determination is made, the internal resistance value r for which the state of charge cannot be calculated with high accuracy is invalidated and the state of charge is calculated with high accuracy (Step 312). It is possible to avoid detecting the state. Therefore, in the electric vehicle according to the present embodiment, it is possible to prevent the engine from being unable to start at the time of idling stop / start.
[0031]
(Third embodiment)
Next, a third embodiment in which the present invention is applied to an electric vehicle will be described. The charging state detection system of this embodiment determines whether or not the engine is starting from the voltage generated by the generator 2.
[0032]
As shown in FIG. 5, in this embodiment, an A / D converter 16 for detecting the voltage of the generator 2 is connected to the generator 2 in the charging state detection system 12, which is shown in the first embodiment. The current sensor 7 is missing. An output terminal of the A / D converter 16 is connected to the microcomputer 8. Therefore, in this embodiment, CPU may incorporate a voltage value V _G of the generator 2, that the voltage value V _G to determine whether more than a predetermined value (e.g., 5V or less), the generator 2 It can be determined whether or not the engine is stopped, in other words, whether or not the engine is stopped (when starting).
[0033]
As shown in FIGS. 3 and 5, in this embodiment, in step 310, in order to determine the operating state of the engine 4, it is determined whether the voltage value V _G of the generator 2 is 5 V or less, and an affirmative determination (engine If it is “stopped”, the process proceeds to the next step 312, and if negative, the process returns to step 302.
[0034]
As described above, in this embodiment of the electric vehicle in the mounted state of charge detection system 12, the voltage value V _G of the generator 2 determines whether the following 5V (engine stopped) (step 310), the negative determination In some cases, the internal resistance value r, which cannot accurately calculate the state of charge, is invalidated and the state of charge is calculated with high accuracy (step 312). be able to. Therefore, in the electric vehicle according to the present embodiment, it is possible to prevent the engine from being unable to start at the time of idling stop / start.
[0035]
In the above embodiment, an example in which the A / D converter is provided outside the microcomputer 8 has been described. However, the A / D converter may be provided in the microcomputer 8. Moreover, in the said embodiment, although the 36V lead battery was illustrated for the lead battery 1, this invention is applicable also when using a 12V lead battery.
[0036]
【The invention's effect】
As described above, according to the present invention, the charge state calculation means does not use the relationship between the internal resistance value and the charge state with low calculation accuracy, but the relationship between the internal resistance value and the charge state with high calculation accuracy. Since the state of charge of the battery is calculated using this, the effect that the state of charge of the battery can be detected with high accuracy can be obtained.
[Brief description of the drawings]
FIG. 1 is a side view of an electric vehicle according to an embodiment to which the present invention is applicable.
FIG. 2 is a block diagram showing a charging state detection system for an electric vehicle according to the first embodiment.
FIG. 3 is a flowchart showing a charge state detection routine of the charge state detection system.
FIG. 4 is a block diagram showing a charging state detection system for an electric vehicle according to a second embodiment.
FIG. 5 is a block diagram illustrating a charging state detection system for an electric vehicle according to a third embodiment.
FIG. 6 is a current characteristic curve showing the relationship between the internal resistance of a battery and the state of charge with respect to the current flowing through the cell motor.
[Explanation of symbols]
1 Lead battery (battery)
2 Generator 3 Cell motor 4 Engine 8 Microcomputer (determination means, internal resistance calculation means, charge state calculation means)
9 Ignition (IGN) switch 11, 12, 13 Charging state detection system 20 Electric vehicle

Claims (3)

Determination means for determining whether the current value flowing from the battery to the cell motor for engine start via the ignition switch is equal to or greater than a predetermined current value for allowing engine start;
An internal resistance calculating means for calculating an internal resistance value of the battery based on a current value flowing through the engine starting cell motor;
Charge state calculation means for calculating a charge state of the battery according to a predetermined relationship between the internal resistance value of the battery and a charge state determined from the internal resistance value calculated by the internal resistance calculation means;
The charge state calculation means calculates the battery charge state when the determination by the determination means is affirmative, and does not calculate the battery charge state when the determination by the determination means is negative. Charge state detection system. Determination means for determining whether the current value or voltage value of the generator that generates electricity by rotation of the engine is equal to or less than a predetermined value;
Internal resistance calculation means for calculating the internal resistance value of the battery based on the current value or voltage value of the generator;
Charge state calculation means for calculating a charge state of the battery according to a predetermined relationship between the internal resistance value of the battery and a charge state determined from the internal resistance value calculated by the internal resistance calculation means;
The charge state calculation means calculates the battery charge state when the determination by the determination means is affirmative, and does not calculate the battery charge state when the determination by the determination means is negative. Charge state detection system.   The electric vehicle provided with the charge condition detection system of Claim 1 or Claim 2.

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