JP2006351384A - Charging control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging control system capable of inexpensively providing safe charging by determining presence of a protective function of a lithium ion battery pack by a simple method. <P>SOLUTION: A protective switch control circuit 25 causes a constant voltage/constant current control circuit 11 to execute only a closing operation of a charging switch 12 before starting charging and brings it into a stop state, and outputs a charging prohibition signal to a control terminal 26. The charging prohibition signal turns off a charging transistor 5a to open a charging path of a lithium ion battery 3 when a battery pack is a regular product. This operation is not executed if the battery pack is a pirated product. Thereafter, supply of a minute current is directed to the constant voltage/constant current control circuit and a voltage increase value input from a voltage change detection circuit 24 is compared with a predetermined value. When it is larger than the predetermined value, it is determined that the protective function is present and a normal charging operation is directed to the constant voltage/constant current control circuit. When it is determined that the protective function is absent, charging stop or special charging is directed to the constant voltage/constant current control circuit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charge control system that controls charging of a lithium ion battery.

  Lithium ion batteries are not handled in the so-called cell format, but in the form of a battery pack. And since a lithium ion battery has danger, such as an explosion, when it overcharges, the battery pack is equipped with the protection function.

  By the way, in recent years, pirated battery packs are on the market. In this pirated version, there are cases where there is no protection function or a protection function is not sufficient for a low price.

  However, charging of a lithium ion battery is usually performed by connecting the battery pack to a charging control IC that is a so-called charger having a constant voltage and constant current control function. However, charging is performed by detecting only the voltage and temperature of the lithium ion battery. Since charging is started in the same way regardless of whether the battery pack is a genuine product or a pirated version, if the battery pack to be charged is a pirated version, there is a problem that the risk of explosion or the like increases when charging.

  In order to cope with this, for example, an authentication function IC is also mounted on the battery pack, and a microcomputer interposed between the battery pack and the charge control IC recognizes whether the battery pack to be charged is genuine or pirated. However, if the battery pack to be charged is a genuine product, it may be charged as usual, and if it is a pirated version, measures such as not charging may be taken, but this requires a microcomputer and an authentication function IC. Thus, the charge control system becomes expensive.

  The present invention has been made in view of the above, and an object thereof is to obtain a charge control system capable of realizing safe charging at a low price by determining the presence or absence of a protective function of a lithium ion battery pack by a simple method. To do.

  In order to achieve the above-described object, a charging control system according to the present invention includes a control unit that issues a charging condition to be applied to a lithium-ion battery pack to be charged, and the lithium-ion battery pack according to an instruction from the control unit. Charging means for performing charging, and the control means detects the presence or absence of a protective function in the lithium ion battery pack based on a voltage rise change obtained in the course of a pseudo-charging operation, and the detection means detects And setting means for setting the charging condition in accordance with the presence or absence of the protective function.

  According to the present invention, when a lithium ion battery pack has a protection function, paying attention to the fact that a pseudo charge operation that allows a minute current to flow while the charging path of the lithium ion battery in the battery pack is shut off is possible. It is possible to perform appropriate charging control according to the presence or absence of the protective function detected based on the voltage rise change at the time.

  According to the present invention, the presence / absence of the protection function of the lithium ion battery pack can be determined by a simple method, so that it is possible to realize safe charging at a low price.

  Exemplary embodiments of a charge control system according to the present invention will be explained below in detail with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a charge control system according to Embodiment 1 of the present invention. FIG. 1 shows a state where the battery pack 1 is connected to the charge control IC 2.

  The genuine battery pack 1 generally includes a lithium ion battery 3, a protection IC 4 that is a protection function, a charging transistor (which is an FET in the illustrated example) 5a, and a discharging transistor (which is an FET in the illustrated example) 5b, Is installed. A parasitic diode exists in parallel in the charging transistor 5a and the discharging transistor 5b.

  In addition, a positive power supply terminal 6 and a negative power supply terminal 7 are provided as external terminals. The positive power supply terminal 6 is connected to the positive electrode end of the lithium ion battery 3. The negative power supply terminal 7 is connected to the negative electrode end of the lithium ion battery 3 through a series circuit of a charging transistor 5a and a discharging transistor 5b. In a pirated battery pack having no protection function, the negative electrode end of the lithium ion battery 3 is directly connected to the negative power supply terminal 7.

  The protection IC 4 monitors the voltage and current of the lithium ion battery 3, and when the voltage or current is other than the specified value, the corresponding one of the charging transistor 5a and the discharging transistor 5b is turned off to turn on the charging path or The discharge path is blocked to protect against dangers such as explosions.

  In such a regular battery pack 1, in the first embodiment, resistance elements 8a and 8b are provided between the control electrodes (gate electrodes in the illustrated example) of the charging transistor 5a and the discharging transistor 5b and the protection IC. The control terminal 9 is provided as an external terminal, and the gate electrode of the charging transistor 5 a is connected to the control terminal 9. This control terminal 9 does not exist in a pirated battery pack having no protection function.

  Next, the charging control IC 2 generally includes a constant voltage constant current control circuit 11, and includes a charging switch 12 and a current detection resistor 13 as external devices. As external terminals, a ground terminal 14, a voltage monitoring terminal 15, a control terminal 16, and voltage monitoring terminals 17 and 18 are provided.

  The ground terminal 14 is grounded internally, but is connected to the ground line 20 together with the negative power supply terminal 7 when the battery pack 1 is connected. The voltage monitoring terminal 15 is connected to the constant voltage constant current control circuit 11 and is connected to one end of the charging switch 12. One end of the charging switch 12 is connected to the positive power supply terminal 6 of the battery pack 1 via the charging line 21 when the battery pack 1 is connected. The control end of the charging switch 12 is connected to the constant voltage / constant current control circuit 11 via the control terminal 16. The other end of the charging switch 12 is connected to the charging line 22 via the current detection resistor 13. Both ends of the current detection resistor 13 are connected to the constant voltage constant current control circuit 11 via current monitoring terminals 17 and 18.

  In general, when the constant voltage constant current control circuit 11 detects the connection of the battery pack 1, the charging switch 12 is closed to start charging, the voltage at one end of the charging switch 12, and the current detection resistor 13. It is a so-called charger that charges the battery pack 1 by constant voltage and constant current control based on the current flowing in the battery.

  In such a charging control IC 2, in the first embodiment, a voltage change detection circuit 24 and a protection switch control circuit 25 are added, and a control terminal 26 is added as an external terminal. In the first embodiment, the constant voltage / constant current control circuit 11 performs various charging operations described later in addition to the normal charging operation described above under the control of the protection switch control circuit 25. .

  The voltage change detection circuit 24 takes in the voltage at one end of the charge switch 12 via the voltage monitoring terminal 15 under the control of the protection switch control circuit 25, detects the voltage increase change within a certain time, and protects it. This is given to the switch control circuit 25.

  The protection switch control circuit 25 outputs a charge prohibition and release control signal to the control terminal 26, and controls the on / off operation of the charging transistor 5a in the genuine battery pack 1 to force the charging path of the lithium ion battery 3. The function of opening and closing automatically, the function of supplying a small current to the constant voltage / constant current control circuit 11 when a control signal for prohibiting charging is output to the control terminal 26, and realizing the pseudo charge operation, and the voltage in the process of the pseudo charge operation A function for determining the presence or absence of the protection function of the battery pack 1 from the voltage rise value input from the change detection circuit 24, and causing the constant voltage / constant current control circuit 11 to perform a normal charging operation based on the determination result, charging stop or special And a function of setting a charging condition for performing a simple charge (a minute current charge, a short time charge, etc.) and controlling the constant voltage constant current control circuit 11.

  Next, the operation of the charge control system according to Embodiment 1 configured as described above will be described. When the battery pack 1 is connected to the charging control IC 2, the protection switch control circuit 25 that detects the battery pack 1 causes the constant voltage / constant current control circuit 11 to perform only the closing operation of the charging switch 12 before starting charging. First, a charge prohibition signal is output to the control terminal 26. If the battery pack 1 is a genuine product, the charging prohibiting signal is turned off through the control terminal 9 connected to the control terminal 26 to open the charging path of the lithium ion battery 3. If the battery pack 1 is a pirated version, the operation of opening the charging path of the lithium ion battery 3 is not performed.

  Thereafter, the constant voltage / constant current control circuit 11 is instructed to supply a minute current, the voltage change detection circuit 24 is instructed to start a detection operation, and the input from the voltage change detection circuit 24 is waited. If the battery pack 1 is a regular product, since the charging path of the lithium ion battery 3 is open, the positive terminal voltage apparently increases. On the other hand, if the battery pack 1 is a pirated version, the charging path of the lithium ion battery 3 is closed, so that charging with a very small current is performed and there is almost no such voltage increase.

  Therefore, the protection switch control circuit 25 compares the voltage increase value input from the voltage change detection circuit 24 with a predetermined value for determination prepared in advance, and if the voltage increase value exceeds the predetermined value, the protection switch control circuit 25 It is determined that there is a protection function. In this case, the protection switch control circuit 25 outputs a control signal for canceling the prohibition of charging to the control terminal 26 and turns on the charging transistor 5a so as to return the charging path of the lithium ion battery 3 to the closed state. The normal voltage / current control circuit 11 is instructed to perform a normal charging operation.

  On the other hand, when the voltage increase value input from the voltage change detection circuit 24 does not exceed, it is determined that the battery pack 1 has no protection function or has a protection function but is insufficient, depending on the extent of not exceeding. In this case, the protection switch control circuit 25 outputs a control signal for canceling the charge prohibition to the control terminal 26 and stops charging (opening operation of the charge switch 12) to the constant voltage / constant current control circuit 11 or special charging (small amount). Current charging, short-time charging, etc.).

  As described above, according to the first embodiment, the charging operation can be adjusted according to the presence or absence of the protection function in the battery pack, so that safe charging is possible. In addition, since a microcomputer and an authentication function IC are not required and the battery pack can be handled by making a small change to the conventional component, a charge control system can be realized at a low cost.

Embodiment 2. FIG.
FIG. 2 is a block diagram showing a configuration of a charge control system according to Embodiment 2 of the present invention. In FIG. 2, the same reference numerals are given to components that are the same as or equivalent to the components shown in FIG. 1 (Embodiment 1). Here, the description will be focused on the portion related to the second embodiment.

  As shown in FIG. 2, in the charge control system according to the second embodiment, a battery pack 30 is provided instead of the battery pack 1 in the configuration shown in FIG. 1 (first embodiment). In the battery pack 30, the resistance elements 8 a and 8 b are deleted from the battery pack 1 shown in FIG. 1, and the protection IC 2 is a protection IC 32 to which a control unit 31 is added. Each gate electrode of the charging transistor 5 a and the discharging transistor 5 b is connected to the control unit 31.

  The control unit 31 receives a control signal for prohibiting and releasing charging applied to the control terminal 9, and controls the on / off operation of the charging transistor 5a to forcibly open and close the charging path of the lithium ion battery 3. It is like that.

  Here, in the first embodiment in the pseudo charge operation, the protection switch control circuit 25 generates a voltage signal for controlling the on / off operation of the charging transistor 5a to forcibly open and close the charging path of the lithium ion battery 3. Although it has been realized, since there are variations in element characteristics, it is difficult to set a general voltage signal level, and there is a possibility that the on / off operation control of the charging transistor 5a cannot be reliably performed.

  On the other hand, according to the second embodiment, the protection switch control circuit 25 only needs to output a binary level signal that can be easily set to the control unit 31, so that the circuit configuration of the protection switch control circuit 25 is as follows. Can be facilitated. In addition, since the on / off operation of the charging transistor 5a can be reliably controlled, safer control is possible.

Embodiment 3 FIG.
FIG. 3 is a block diagram showing a configuration of a charge control system according to Embodiment 3 of the present invention. In FIG. 3, the same reference numerals are given to components that are the same as or equivalent to the components shown in FIG. 2 (Embodiment 2). Here, the description will be focused on the portion related to the third embodiment.

  As shown in FIG. 3, the charge control system according to the third embodiment is provided with a charge control IC 34 instead of the charge control IC 2 in the configuration shown in FIG. 2 (second embodiment). In the charge control IC 34, the voltage change detection circuit 24 is deleted from the charge control IC 2 shown in FIG. 2, and a voltage change detection circuit 36 is provided on the current monitoring terminals 17 and 18 side. The constant voltage / constant current control circuit 36 with the sign changed obtains current information from the detection voltage of the voltage change detection circuit 36.

  The voltage change detection circuit 36 receives an operation start instruction from the protection switch control circuit 25 when the pseudo charge operation is started, and the voltage increase change within a predetermined time from the voltage drop when the current flows through the current detection resistor 13. Is supplied to the protection switch control circuit 25.

  The voltage change detection circuit 36 receives an instruction to start the operation from the protection switch control circuit 25 when the normal charging operation is started, and the voltage drop when the current flows through the current detection resistor 13 is set to a constant voltage. This is given to the current control circuit 36.

  Here, in the pseudo charge operation, in the first and second embodiments, the increase level of the battery voltage is detected, but the increase level of the battery voltage may depend on the characteristics of the battery pack. Specifically, for example, in a battery pack without a protection function, the voltage value that rises within a certain time due to flowing a minute current changes depending on the internal resistance of the lithium ion battery 3. For this reason, it is difficult to accurately set the voltage increase within a certain time as a predetermined value for determination in the protection switch control circuit 25.

  On the other hand, in the third embodiment, since a small constant current as a set value detects a voltage increase change within a certain time from a voltage drop when a current flows through the current detection resistor 13, the characteristics of the battery pack are detected. A voltage rise value that does not depend on. Therefore, the predetermined value for determination can be accurately determined.

  It should be noted that in the pseudo charge operation, the charging path of the lithium ion battery 3 is open in the genuine battery pack, so that no charging current flows. On the other hand, in the pirated battery pack, the charging path of the lithium ion battery 3 is closed, so that a charging current flows. Therefore, the magnitude comparison with the predetermined value in the protection switch control circuit 25 has a reverse relationship with the first and second embodiments.

  As described above, the charge control system according to the present invention is useful for realizing safe charging of a lithium ion battery at a low price.

It is a block diagram which shows the structure of the charge control system by Embodiment 1 of this invention. It is a block diagram which shows the structure of the charge control system by Embodiment 2 of this invention. It is a block diagram which shows the structure of the charge control system by Embodiment 3 of this invention.

Explanation of symbols

1 Battery pack 2 Charge control IC
3 Lithium ion battery 4 Protection IC
5a Charging transistor (switch in battery pack)
5b Discharge transistor 6 Positive power supply terminal 7 Negative power supply terminal 8a, 8b Resistive element 9 Control terminal 11 Constant voltage constant current control circuit 12 Charge switch 13 Current detection resistor 14 Ground terminal 15 Voltage monitoring terminal 16 Control terminal 17, 18 Current Monitoring terminal 20 Ground line 21, 22 Charging line 24 Voltage change detection circuit 25 Protection switch control circuit 30 Battery pack 31 Control unit 32 Protection IC
34 Charge control IC
35 Voltage change detection circuit 36 Constant voltage constant current control circuit

Claims (4)

Control means for issuing charging conditions to be applied to the lithium-ion battery pack to be charged;
Charging means for charging the lithium ion battery pack according to an instruction from the control means,
The control means includes
Detecting means for detecting the presence or absence of a protective function in the lithium ion battery pack based on a voltage increase change obtained in the process of a pseudo-charging operation;
Setting means for setting the charging condition according to the presence or absence of the protection function detected by the detection means;
A charge control system comprising: The detection means includes
Directly controlling a switch inserted in the charging path of the lithium ion battery in the lithium ion battery pack or giving an instruction to a means for controlling the switch provided in the lithium ion battery pack, the switch Means for performing an open circuit operation,
Thereafter, the charging means is instructed to perform charging with a minute current to detect a voltage rise change of a charging line to which the lithium ion battery pack is connected, or a current detecting resistor inserted in the charging line Means for detecting a voltage rise change from the voltage drop at the container;
When the detected voltage increase value is compared with a predetermined value, and the voltage increase value exceeds the predetermined value, it is determined that the lithium ion battery pack has a normal protection function, and the voltage increase value does not exceed the predetermined value. Means to determine that the lithium ion battery pack has no protective function, or has a protective function but is insufficient,
The charging control system according to claim 1, further comprising: The setting means includes
When it is determined that the detection means has a normal protection function, a normal charging condition is set. When it is determined that the detection means does not have a protection function, or the protection means has a protection function, it is insufficient. When it is determined that charging is stopped, or a special charging condition is set, an instruction according to each charging condition is output to the charging means.
The charge control system according to claim 1.   The charge control system according to claim 3, wherein the special charging condition is minute current charging or short-time charging.

Images