Battery pack, battery charger, and battery pack system

A battery pack includes: a plurality of rechargeable batteries (11a to 11n) connected in series or in parallel; a voltage detector (13) for detecting voltages of the respective batteries; a calculator (15) for calculating optimal charging current values based on the voltages of the respective batteries detected by the voltage detector so as to recharge the respective batteries; and a communicator (19) for transmitting the charging current values calculated by the calculator to a battery charger (3).

TECHNICAL FIELD

The present invention relates to a rechargeable battery pack, a battery charger, and a rechargeable battery pack system, which are used for a hybrid vehicle, a running power source for an electrically power assisted cycle, and the like. More specifically, the present invention relates to an interface between the rechargeable battery pack and the battery charger, and a technique for a control system of the battery charger.

BACKGROUND ART

In a circuit configuration of a conventional battery pack system illustrated inFIG. 1, a battery charger3ehad controlled a charging voltage and a charging current so as to supply the charging voltage and the charging current to a battery pack1e. For example, as illustrated inFIG. 2, a battery charge had been controlled by a method of a CCCV charge, i.e. recharging at a set current Is in a constant current charge period T1, and recharging at a set voltage Vs in a constant voltage charge period T2.

Thus, the conventional battery pack system had recharged a secondary battery (hereinafter, referred to as a battery) in the battery pack, while the battery charger had monitored the charging voltage and the charging current.

Meanwhile, there were cases where the conventional battery pack system could not recharge the battery in the battery pack appropriately depending on conditions of a temperature of the battery pack and an internal resistance of the battery.

As for a technique for the conventional battery pack system, a battery charger described in PTL 1 has been known. The battery charger includes a first charge controller for recharging a battery so that a charge amount of the battery becomes a first charge amount, a second charge controller for recharging the battery so that the charge amount of the battery becomes a second charge amount smaller than the first charge amount, and a selector for selecting between charge processing by the first charge controller and charge processing by the second charge controller.

In other words, the conventional battery charger selects between a charge method for prioritizing battery life and a charge method for prioritizing a reduction of a charge time when recharging the battery. The battery charger can also select other methods depending on temperature and user purposes.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

However, the conventional battery charger described in PTL 1 did not include a method in which a battery pack could specify a charging current with respect to a battery charger. Accordingly, there was a problem of the battery charger incapable of recharging the battery pack appropriately according to a condition of the battery pack.

To solve the above-mentioned problem, it is an object of the present invention to provide a battery pack, a battery charger and a battery pack system capable of recharging the battery pack in an optimal condition and in a short period of time according to a condition of the battery pack.

A battery pack according to a first aspect of the present invention is a rechargeable battery pack to be recharged by a battery charger, including: a plurality of rechargeable batteries connected in series or in parallel; a voltage detector for detecting voltages of the respective rechargeable batteries; a calculator for calculating optimal charging current values based on the voltages of the respective batteries detected by the voltage detector so as to recharge the respective batteries; and a communicator for transmitting the charging current values calculated by the calculator to the battery charger.

The battery pack according to the first aspect of the present invention may further include: a temperature sensor for measuring temperatures of the batteries; an input circuit in which a battery charger condition signal indicating a condition of the battery charger is input from the battery charger; an output circuit that outputs a battery pack condition signal indicating a condition of the battery pack to the battery charger; and a controller for controlling the voltage detector, the calculator, the communicator, the input circuit, and the output circuit. The calculator calculates optimal current values based on the voltages of the respective batteries detected by the voltage detector and the temperatures of the respective batteries measured by the temperature sensor.

The battery pack according to the first aspect of the present invention may further include: a power supply that is activated by the battery charger condition signal input from the battery charger via the input circuit, and supplies a current for operating the controller to the controller.

A battery charger according to a second aspect of the present invention is a battery charger for recharging the battery pack according to the first aspect of the present invention, including: a current controller for supplying currents according to the charging current values from the battery pack to the batteries in the battery pack.

A battery pack system according to a third aspect of the present invention includes: a battery charger; and a rechargeable battery pack to be recharged by the battery charger. The battery pack includes: a plurality of rechargeable batteries connected in series or in parallel; a voltage detector for detecting voltages of the respective rechargeable batteries; a calculator for calculating optimal charging current values based on the voltages of the respective batteries detected by the voltage detector so as to recharge the respective batteries; and a communicator for transmitting the charging current values calculated by the calculator to the battery charger. The battery charger comprises a current controller that supplies currents according to the charging current values from the battery pack to the batteries in the battery pack.

According to the battery pack of the first aspect of the present invention, the voltage detector detects the voltages of the respective batteries, the calculator calculates the optimal charging current values based on the detected voltages of the respective batteries so as to recharge the respective batteries, the communicator transmits the calculated charging current values to the battery charger, and the current controller of the battery charger supplies the currents according to the charging current values from the battery pack to the batteries in the battery pack.

Namely, the battery pack calculates the optimal charging current values and specifies the charging current values with respect to the battery charger, thereby controlling the battery charger. Therefore, the battery pack is recharged in an optimal condition and in a short period of time according to the condition of the battery pack.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a description will be made below in detail of a battery pack, a battery charger, and a battery pack system in examples according to the present invention with reference to the drawings.

FIG. 3is a circuit configuration diagram of a battery pack system of Example 1. InFIG. 3, the battery pack system includes a rechargeable battery pack1, and a battery charger3for recharging rechargeable batteries in the battery pack1.

The battery pack system monitors charged conditions of the batteries by a voltage detector for detecting voltages of the respective batteries in the battery pack1and a temperature sensor for sensing temperatures of the respective batteries, calculates current values in this point for recharging the batteries by a charging current calculator according to the monitored data, and transmits the current values to the battery charger via a communication I/F, thereby controlling charging currents.

The battery pack1includes a plurality of rechargeable batteries11ato11n(hereinafter, “n” means that an arbitrary number of one or more batteries are connected) connected in series, a plurality of resistors12ato12(n+1) (hereinafter, “n” means that one or more of resistors with the same number as the batteries are connected) connected to both terminals of the rechargeable batteries11ato11n, a voltage detector13for detecting voltages of the rechargeable batteries11ato11n, a temperature sensor14for sensing temperatures of the rechargeable batteries11ato11n, a microprocessor unit (MPU)15for controlling each component, a current controller16, a communication interface (communication I/F)19, an input port20, and an output port21.

The current controller16controls charging currents from the battery charger3via a port P1. The controlled charging currents are supplied to the batteries11ato11nand a power supply17. The power supply17generates power by the charging currents from the battery charger3and voltages of the batteries11ato11n. Then, the power is supplied to the MPU15via a diode18, whereby the MPU is operated.

The communication I/F19(communicator) performs data communication with the battery charger3. The input port20inputs a battery charger condition signal indicating a condition of the battery charger3from the battery charger3so as to output to the MPU15. The output port21outputs a battery pack condition signal indicating a condition of the battery pack1from the MPU15to the battery charger3.

In addition, the battery charger3includes an MPU31for controlling each component, a current controller32for controlling charging currents, a communication I/F33for performing communication with the battery pack1, an output port34for outputting a battery charger condition signal to the battery pack1, and an input port35for inputting a battery pack condition signal from the battery pack1.

The MPU15(calculator) calculates optimal charging current values for recharging each of the batteries based on voltages of each of the batteries detected by the voltage detector13and temperature data sensed by the temperature sensor14. Then, the communication I/F19transmits the optimal charging current values calculated by the MPU15to the battery charger3.

As described above, in the battery pack1, the voltage detector13detects the voltages of the respective batteries11ato11n, the MPU15calculates the optimal charging current values for recharging each battery based on the detected voltages of the respective batteries11ato11nand the temperature data from the temperature sensor14, and the communication I/F19transmits the calculated charging current values to the battery charger3. In the battery charger3, the current controller32supplies currents according to the charging current values from the battery pack1to the batteries11ato11nin the battery pack1.

Namely, the battery pack1calculates the optimal charging current values, and specifies the charging current values with respect to the battery charger3, so as to control the battery charger3. Thus, the battery charger3can recharge the battery pack1in an optimal condition and in a short period of time according to the condition (e.g. temperature and internal resistance) of the battery pack1.

Moreover, the battery charger3and the battery pack1can mutually indicate the own conditions each other by use of the input port20and output port21. In other words, when the battery charger3is in a condition capable of recharging the batteries, the MPU31in the battery charger3outputs a signal indicating the condition capable of recharging the battery pack1to the MPU15from the output port34in the battery charger side via the input port20in the battery pack side. Thus, the battery charger3indicates the charge-standby condition with respect to the battery pack1.

In addition, when the MPU15in the battery pack1detects the connection to the battery charger3by the signal from the input port20, the MPU15evaluates the conditions of the batteries11ato11n. When the batteries11ato11nare in a rechargeable condition, a signal in an output-standby condition is output to the battery charger3from the output port21in the battery pack side. Then, the battery pack1indicates the charge-standby condition to the battery charger3.

As described above, the signals from the input port20and the output port21are used as handshake signals. Then, the batteries11ato11nare recharged when both the battery pack1and the battery charger3are only in a normal condition, thereby completing recharging securely. Moreover, when the battery charger3and the battery pack1are both in the normal condition, the optimal charging current values calculated by the MPU15are indicated to the battery charger3via the communication I/F19. The charging current values are output to the battery charger3from the output port21as coded values.

FIG. 4is a circuit configuration diagram of a battery pack system of Example 2. InFIG. 4, the battery pack system further includes a diode23, and a power supply22that is activated by a battery charger condition signal input from the battery charger3via the input port20and supplies a current to the MPU15via the diode23to operate the MPU15, in addition to the configuration of the battery pack system of Example 1 illustrated inFIG. 3.

Note that, in Example 2, the same components as Example 1 are indicated by the same numerals, and explanations thereof are omitted.

In the configuration of Example 2 as described above, the power supply22is activated by the battery charger condition signal input from the battery charger3via the input port20, and supplies the current to the MPU15via the diode23to operate the MPU15. Therefore, the power supply22operates the MPU15in the battery pack1even when the battery charger3is not in a state supplying the charging currents and the batteries in the battery pack1are not sufficiently recharged enough to operate the MPU15.

FIG. 5is a circuit configuration diagram of a battery pack system of Example 3. InFIG. 5, the battery pack system includes a different component, an MPU31ain a battery charger3b, from the battery pack system of Example 2 illustrated inFIG. 4.

Note that, in Example 3, the same components as Example 2 illustrated inFIG. 4are indicated by the same numerals, and explanations thereof are omitted.

The communication I/F19in a battery pack1boutputs a status signal of the battery pack1bin the MPU15to a communication I/F33in the battery charger3b. Then, the output port21in the battery pack1boutputs a charge available condition signal of the battery pack1bto the input port35in the battery charger3b.

The communication I/F33in the battery charger3bobtains the status signal of the battery pack1from the communication I/F19. Then, the input port35inputs the charge available condition signal of the battery pack1from the output port21.

The MPU31ain the battery charger side transmits a signal for recharging the batteries to the current controller32when the status signal from the communication I/F33and the charge available condition signal from the input port35are both only in a normal condition.

Thus, only when the battery pack1and the battery charger3are normally connected and recharging is in a normally available condition, the charging currents can be applied to the batteries11ato11n. Therefore, an electrical shock accident and a short circuit accident caused by allowing the charging currents are avoided when the battery pack1is in an anomalous charge condition or the battery pack1is not connected.

FIG. 6is a diagram for explaining charging current specifying operations and charge mode specifying operations of a battery pack system in Example 4. A circuit diagram of Example 4 is approximately the same as the circuit diagram illustrated inFIG. 3.

The MPU15in the battery pack1of Example 4 outputs the charging current values and other information to the communication I/F19. The communication I/F19outputs the charging current values and the other information from the MPU15to the communication I/F33in the battery charger3.

For example, as illustrated inFIG. 6, the charging current values are specified in a phased manner, or a constant current charge mode (constant current charge period T1) and a constant voltage charge mode (constant voltage charge period T2) are specified, from the battery pack1to the battery charger3. Thus, optimal charge characteristics can be achieved.

In addition, the MPU15in the battery pack1can specify the charging current values per communication. Therefore, a battery charge control can be performed sensitively.

Furthermore, the MPU15can also transmit information of the charging current values and the charge modes to the battery charger3by use of the input port20and the output port21.

FIG. 7is a diagram for explaining a charge time limit of a battery pack system in Example 5. A circuit diagram of Example 5 is approximately the same as the circuit diagram illustrated inFIG. 3.

The MPU15in the battery pack1of Example 5 transmits information of a battery charge limit period via the communication I/F19or the input port20and output port21. The MPU31in the battery charger3controls recharging of the batteries11ato11nin the battery pack1so as to stop within the charge limit period in accordance with the charge limit period from the battery pack1.

Thus, as illustrated inFIG. 7, even when an anomalous charging current is kept applying during recharging due to a trouble of the battery pack1, the MPU31in the battery charger3stops recharging the batteries11ato11nin the charge limit time T3. This avoids the battery pack1from overheating and igniting.

Moreover, the MPU15in the battery pack1can also vary the charge limit time T3at arbitrary timing by use of the communication I/F19or the input port20and output port21. For example, the charging currents to the batteries11ato11nneed to be reduced at low temperature. In this case, the batteries11ato11nare recharged while sufficiently taking a time by extending the charge limit time T3.

FIG. 8is a diagram for explaining status storage operations in a battery pack and a battery charger of Example 6. A circuit diagram of Example 6 is approximately the same as the circuit diagram illustrated inFIG. 3.

The battery pack1of Example 6 transmits a status of the battery pack1to the battery charger3via the communication I/F19or the input port20and output port21. Also, the battery charger3transmits a status of the battery charger3to the battery pack1via the communication I/F33or the input port34and the output port35.

As illustrated inFIG. 8, in the battery pack1and the battery charger3, the battery pack status transmitted to the battery charger side and the battery charger status received from the battery charger side are stored in a battery pack side memory25in chronological order. Also, the battery charger status transmitted to the battery pack and the battery pack status received from the battery pack are stored in a battery charger side memory36in chronological order.

Therefore, when a trouble is caused in either the battery pack1or the battery charger3, a condition at the trouble can be found by use of the status information stored in the other side even when the status information at the trouble is not stored in the troubled side. Thus, it can be easily analyzed a cause of the trouble.

FIG. 9is a diagram for explaining a function of connector pins for recharging in a battery pack system of Example 7. InFIG. 9, a battery charger side connector4is provided in a battery charger3c, and a battery pack side connector8is provided in a battery pack1c. The battery pack side connector8is configured so as to be removably attachable from the battery charger side connector4.

A charging current pin5a, a charging current pin5b, a battery charger condition signal pin6a, and a battery pack condition signal pin6bare provided in the battery charger side connector4. Lengths of the battery charger condition signal pin6aand the battery pack condition signal pin6bare shorter than lengths of the charging current pins5aand5b.

A connector socket8ais provided with the battery pack side connector8. a groove9afor engaging with the charging current pin5a, a groove9bfor engaging with the charging current pin5b, a groove10afor engaging with the battery charger condition signal pin6a, and groove10bfor engaging with the battery pack condition signal pin6bare provided in the connector socket8a.

Namely, when the battery charger side connector4is attached to the battery pack side connector8the respective battery charger pins5a,5b,6aand6bare attached to the respective grooves9a,9b,10aand10b, and when the battery charger side connector4is removed from the battery pack side connector8the respective battery charger pins5a,5b,6aand6bare removed from the respective grooves9a,9b,10aand10b.

A battery pack condition signal is input to the battery charger3cvia the battery pack condition signal pin6b. The battery pack condition signal is configured to be in a condition that the battery pack1cis in a normal condition with an L level. The battery charger3cfurther includes an inverter37for inverting the battery pack condition signal input via the battery pack condition signal pin6bso as to output the signal to the MPU31, and a resistor36connected between a power source Vcc and an input side of the inverter37.

In such a configuration, when the battery charger side connector4is connected to the battery pack side connector8, the L level of the battery pack condition signal is inverted to be an H level. Then, when the H level is input to the MPU31, the MPU31determines that the battery pack1cis in a normal condition.

While, when the battery charger side connector4starts disconnecting the battery pack side connector8, the battery charger condition signal pin6aand the battery pack condition signal pin6bdisconnect the grooves10aand10bfirst. Thus, the battery pack condition signal and the battery charger condition signal are interrupted.

Then, the MPU31determines that the conditions of the battery pack1cand the battery charger3care in an anomalous condition due to the interruption of the battery pack condition signal and the battery charger condition signal. As a result, the MPU31controls the current controller32so as to immediately interrupt the charging currents.

Moreover, the MPU31in the battery charger3ccontrols the current controller32so as to immediately interrupt the charging currents when the battery pack condition signal becomes the H level, i.e. the battery pack1cis in an anomalous condition. Therefore, the charging currents can be immediately interrupted when the battery charger side connector4starts disconnecting the battery pack side connector8, whereby an electrical shock accident and the like can be avoided.

FIG. 10is a view for explaining a function of a connecting/disconnecting detection of a connector for recharging in a battery pack system of Example 8. Note that, the same components as Example 7 illustrated inFIG. 9are indicated by the same numerals, and explanations thereof are omitted.

InFIG. 10, a cover7for covering the respective pins5a,5b,6aand6bof the battery charger side connector4is provided with the battery charger side connector4. Therefore, the charging current pins5aand5bcan be isolated externally, thereby avoiding an electrical shock accident.

In addition, a switch7afor detecting a connection/disconnection of the battery charger side connector4with respect to the battery pack side connector8is provided in the cover7, for example. When the battery charger side connector4starts disconnecting the battery pack side connector8, a connection between a protrusion, not illustrated in the figure, provided in the connector socket8aand the switch7ais interrupted. Then, the switch7aturns off, thereby transmitting an off signal to the MPU31via the input port35.

When the MPU31detects the off signal from the switch7a, the MPU31controls the current controller32so as to immediately interrupt the charging currents. Thus, the charging currents are immediately interrupted when the battery charger side connector4starts disconnecting. Accordingly, risk of an electrical shock accident caused by touching the exposed charging current pins5aand5bis reduced.

FIG. 11is a diagram for explaining a function of a battery charger connecting detection in a battery pack system of Example 9. Charging current terminals TP1and TP2of a battery charger3dillustrated inFIG. 11are connected to charging current terminals TP3and TP4of a battery pack1d, respectively. Then, a charging voltage detector25provided in the battery pack1ddetects a voltage between the charging current terminals TP1and TP2of the battery charger3d, and interrupts an MPU15ain the battery pack1d.

In such a configuration, not only the battery charger3including the communication I/F33, the input port34, and the output port35, which are provided between the battery charger3and the battery pack1as illustrated inFIG. 3, but also a combination of the battery charger3dand the battery pack1d, terminals of which are providing only the charging current terminals, can control the charging currents from the battery charger to the battery pack. In other words, when the battery charger3dnot providing the battery charger condition signal is connected to the battery pack1d, the connection of the battery charger3dto the battery pack1dcan be detected only by use of the charging voltage by the charging voltage detector25.

FIG. 12is a diagram for explaining operations for measuring a charged number in a battery pack system of Example 10. Example 10 is characterized by a measurement of the charged number of the batteries11ato11n.

The battery pack system of Example 10 confirms the connection between the battery charger3and the battery pack1by use of, e.g. the battery charger condition signal and the battery pack condition signal, and permits to recharge by specifying the charging currents and the like (similar as Example 1). Then, the voltage detector13detects voltages of the batteries11ato11n. As illustrated inFIG. 12, when the charge amount exceeds a specified charge amount (specified charge amount Q2inFIG. 12), a counter, not illustrated in the figure, provided in the MPU15counts the present recharging as one of the charged number.

Meanwhile, when there is no handshake signal such as the battery charger condition signal and the battery pack condition signal between the battery charger3and the battery pack1, the connection of the battery charger3is detected by the voltage detected by the charging voltage detector25as illustrated inFIG. 11. In this point, the voltage detector13detects the voltages of the batteries. Then, when the charge amount exceeds a threshold value, the counter, not illustrated in the figure, provided in the MPU15counts the present recharging as one of the charged number. Accordingly, the charged number of the batteries11ato11nis counted as accurately as possible.

Industrial Applicability

Since it is possible to recharge the battery pack in an optimal condition and in a short period of time according to the condition of the battery pack, the battery pack is superior especially for an application to purposes such as a hybrid vehicle, a running power source for an electrically power assisted cycle, and the like.