GB2447318A

GB2447318A - A Lithium Battery pack and system for charging the same

Info

Publication number: GB2447318A
Application number: GB0800170A
Authority: GB
Inventors: Dezhong Yang
Original assignee: Chevron HK Ltd
Current assignee: Chevron HK Ltd
Priority date: 2007-03-05
Filing date: 2008-01-04
Publication date: 2008-09-10
Anticipated expiration: 2028-01-04
Also published as: AU2007101218A4; GB2447318B; GB0800170D0

Abstract

A lithium battery pack according to the present invention has inherent information stored therein, which comprises number of cells, nominal voltage, maximal voltage of the cells, range of temperature etc. A charging parameter is determined by a charging controller based on an identified data of the cells which includes the state of charge of at least one of the battery cells and is transmitted to an adapter. A controlled module in the adapter receives the charging parameter through a control terminal and adjusts an AC/DC circuit to output a current with accurate charging voltage to the battery pack.

Description

A LITHIUM BATFERY PACK AND SYSTEM FOR CHARGING THE SAME

FIELD OF THE INVENTION

The present invention generally relates to a lithium batteiy pack and charging system thereof, and more particularly, to a lithium batteiy pack for a power tool and system for charging the same.

BACKGROUND OF THE INVENTION

Battery powered power tools are widely used in many fields because of portability.

And rechargeable lithium battery packs with advantages in weight and capacity becomes one of the best choice for the power tools. On the other hand, lithium battery packs have special charging requirement, thus enough safety and efficiency should be reached.

A common charging system for a lithium battery pack has two species: (1) a charger outputs power has constant current or constant voltage for charging a battery pack which has a nominal voltage. The disadvantage is that a charger is only operable to charge a corresponding battery pack; (2) a charger provides different charging parameter based on information of the battery cells which are stored in the battery pack. The disadvantage is that the charger needs to obtain the relative information of the battery pack before charging, and then to confirm the charging parameter, which is obviously complex.

SUMMARY OF THE INVENTION

The advantage of the present invention is that the lithium battery pack according to the present invention could be charged by a common adapter or charger.

In addition, lithium battery packs have different number of cells can be charged by a common adapter.

The lithium battery pack according to the present invention has a charging controller for determining the charging parameter and sending a control signal to an adapter which provides charging energy to the battery pack. A controlled module in the adapter receives the control signal and adjusts an ACIDC circuit to output an accurate voltage.

Furthermore, the charging controller is integrated in the battery pack. Before the process of charging, the charging controller identifies initial data of the lithium battery cells, especially the individual voltage of each cell, through some sensors, such as voltage sensor, temperature sensor, and current sensor. The battery pack also has inherent information stored therein, which comprises number of cells, nominal voltage, maximal voltage of the cells, range of temperature etc. The charging parameter is determined by the charging controller based on the identified data of the cells and the inherent information, and transmitted to the controlled module. The controlled module receives charging parameter through a control terminal and adjusts the ACIDC circuit to provide a current with accurate charging voltage. In the whole charging process, the charging control portion is executed in the battery pack, and the adapter is only operable for providing power as required by the battery pack.

Therefore the charging process will be more accurately, rapidly and safely.

The battery pack also includes protection module for providing charging protection and discharging protection thus to ensure safety of the lithium cells. The protection module includes charging protection module and discharging protection module. The charging protection module has at least one function of over-current protection, overcharge protection, over-voltage protection and monitoring voltages of individual cells; the discharging protection module has at least one function of over-current protection, short preventing and over-discharge protection.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1 is a perspective view of a battery pack.

Figure 2 is a perspective view of an adapter.

Figure 3 shows the battery pack of Figure 1 electrically and physically connected to the adapter of Figure 2.

Figure 4 shows electrical connection between a battery pack and an adapter.

Figure 5 is a circuit schematic view of an adapter.

Figure 6 is a circuit schematic view of a batteiy pack.

Figure 7a and 7b are flowcharts illustrating charging process of the battery pack embodying the present invention.

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.

DETAILED DESCRIPTION OF THE DRAWINGS

A battery pack 10 as illustrated in FIG 1 is adapted for providing power to a power tool. The battery pack 10 includes a housing 20 which encloses a series of battery cells (not shown) and a control circuit 30. Preferably, the battery cells are made of Lithium-based chemical material. The battery pack 10 has a nominal voltage, value of which is determined by individual voltage of each cell and number of cells.

The battery pack 10 is configured to have one or more terminals 3 5-37 and is electrically connectable to an electrical device, such as an adapter 40 and/or a power tool. In some constructions, electrical connection between the terminals needs support of physical connection between the battery pack 10 and the electrical device.

In other constructions, electrical connection is confirmed by signal and then electrical energy is transmitted between the battery pack 10 and the electrical device in waves. In some constructions, as illustrated in FIG 1, the battery pack 10 includes a positive battery terminal 35, a negative battery terminal 36 and a second control terminal 37. In some constructions, the battery pack 10 includes more or fewer terminals.

In some constructions and in some aspects, the battery pack 10 includes a controller or component electrically connected to one or more battery terminals. The controller analyzes the information of the battery pack 10 stored in the circuit 30 to obtain charging parameter, and sends the charging parameter to the electrical device physically connected thereto. The charging parameter could include number of the S 4 cells, nominal voltage, maximal voltage, temperature range, and initial state of the battery cells. In some constructions, the charging controller 60 of a battery pack 10 hasaMCIJ6l.

In some constructions and in some aspects, the battery pack 10 includes a voltage sampling circuit for monitoring voltage of an individual cell 15. The voltage sampling circuit is integrated in the charging controller 60.

As shown in FIGS. 2 and 3, the battery pack 10 is also configured to be connectable with an electrical device, such as an adapter 40. In some constructions, the adapter 40 includes a housing 41. The housing 41 provides a connecting portion 42 to which the battery pack 10 is connected. The connecting portion 42 includes one or more electrical terminals for electrically connecting the adapter 40 to the battery pack 10. The terminals provided in the adapter 40 are configured to mate with the terminals of the battery pack 10 for receiving control signal from the pack and transferring power to the battery pack 10.

In some constructions, as illustrated in F1Ci3, the adapter 40 includes a positive terminal 43, a negative terminal 44, and a first control terminal 45. In some constructions, the first control terminal 45 is configured to mate with the second control terminal 37 of the battery pack 10.

In some constructions and some aspects, the adapter 40 also includes an AC/DC section 46 and a controlled module 47. In some constructions, the controlled module 47 includes a center controlled module 48 and a feedback module 49. The center controlled module 48 could be a MCU with relevant circuit, and the feedback module 49 could be an optocoupler with relevant circuit. The controlled module 47 may also includes indication circuit.

As shown in FIG4, inside the pack 10, the charging controller 60 determines charging mode based on the state of the cells 15 and sends control signal to the second control terminal 37. Inside the adapter 40, the first control terminal 45 receives outside signal contains charging parameter, and the controlled module 47adjusts the AC/DC section 46 to transform AC supply to DC required.

The adapter as shown in FIQ5 includes a transformer 52, a feedback loop, an optically coupled control circuit, a PWM controller 55, and a power MOSFET 56.

The AC supply flows through a EMI suppression circuit 57 and a primary input filtering circuit to the transformer 52, and then passes a secondary rectification circuit to output high voltage DC which flows through the feedback loop, the optocoupler control circuit, and the PWM controller 55. The MCU sends charging control signal to the PWM controller 55 which control the power MOSFET 56 to obtain required outputting voltage or current.

The power supply input circuit 60 could include a fuse, a NTC (negative temperature coefficient), and a varistor (not shown), because of which, when a short is induced, the current flows through the power inputting terminal 65 will not exceed a predetermined value. Such that the impact current occurred at the beginning of the power supplying is reduced. Moreover surge voltage in the inputting line is absorbed to avoid damage of the elements in the adapter 40 brought by over voltage. The rectification circuits rectify ripple voltage in inputting voltage to make it smooth, and to output relatively steady DC voltage. Meanwhile the rectification circuits filter high frequency switching noise to improve transmitting character.

The charging controller 60 of the battery pack 10 includes the MCU 61 and a MOSFET 70 which controls switching on/off of the MCU 61, shown in FIG6. The charging controller 60 further includes a voltage sampling circuit 71, a current sampling circuit 72, and a temperature sampling circuit 73, through which the MCU 61 obtains current value of the voltage, current and temperature of the battery pack and sends charging signal to the second control terminal 37 through matching network 74. The MCU 61 controls outputting voltage of the adapter 40 in such a way that when temperature of the cells 15 lies within a predetermined allowed range and the voltage of an individual cell is higher than a predetermined allowed charging voltage, the battery pack 10 is charged in constant current; otherwise, when the voltage of an individual cell equal to or greater than 4.2V, the battery pack 10 is charged in constant voltage, meanwhile, the MCU 61 monitors the temperature and current, and shuts down the charging process if the current rate is smaller than 0.1 C. The charging control workflow mainly comprises two modules, which are determination module 100 as shown in FJG7A and execute module 150 as shown in FIG 78. The determination module 100 judges if there is an adapter is coupled to the battery pack 10 at step 105, which is confirmed if terminals of the battery pack 10 and the adapter 40 are connected. When the adapter 40 is coupled to the pack 10, the charging controller 60 reads the information of the adapter 40, such as type of the adapter, range of the voltage, and range of the current, through the control terminal, and determines whether the adapter 40 mates with the battery pack 10 at step 110. If they mate each other, the process shifts to the execute module 150.

In the execute module 150, the battery pack 10 monitors state of the cells 15 to determine whether the cells should be charged in constant voltage at step 155. If constant-voltage charging requirement is reached, the process shifts to step 165 which is the constant-voltage charging module, otherwise the process shifts to step which is the constantcurrent charging module. After the constant-current charging process at step 160 is finished, the process shifts to the step 165. After the constant-voltage charging process at step 165 being finished, the charging controller estimate whether the cells are full charged at step 170. Operation returns to step if the cells are not full charged, otherwise the MOSFET 70 will end the charging process. If the battery pack 10 is still coupled with the adapter 40, it needs to determine whether a supplement charge is required, if yes, the process returns to step 155, otherwise to close the power supply. The constant-current charging and constantvoltage charging are performed by either P11) control or fuzzy control. A temperature judgment module is executed in the whole charging process.

The advantage of the present invention is that lithium-based battery packs with different charging parameter could be charged by a common adapter or charger.

Claims

What is claimed is: 1. An electrical combination comprising: a first

battery pack having a plurality of lithium-based battery cells, each of which having an individual state of charge, wherein the first battery pack having a first charging controller operable to monitor the individual state of charge of at least one battery cell and to control a charging current being supplied to the first battery pack based at least in part on the state of charge of at least one battery cell; a second battery pack having a plurality of lithium-based battery cells, each of which having an individual state of charge, wherein the second battery pack having a second charging controller operable to monitor the individual state of charge of at least one battery cell and to control a charging current being supplied to the second battery pack based at least in part on the state of charge of at least one battery cell; and an electrical device; wherein total number of the plurality of lithium-based battery cells in the first battery pack is different than total number of the plurality of lithium-based battery cells in the second battery pack; the electrical device is operable to supply power to the first battery pack and the second battery pack.
2. An electrical combination as set forth in claim 1, wherein the electrical device is a power adapter.
3. An electrical combination as set forth in claim 2, wherein the power adapter includes: an AC/DC circuit; a first control terminal for receiving a charging control signal sent by one of the first charging controller and the second charging controller; two voltage output terminals, and a controlled module; wherein the controlled module controls the AC/DC circuit to output a current with S 8 accurate charging voltage according to the charging control signal received from the first control terminal.
4. An electrical combination as set forth in claim 3, wherein the control signal is one of the voltage signal and current signal.
5. An electrical combination as set forth in claim 1, wherein the electrical device includes a controlled module to supply a current with accurate charging voltage.
6. A lithium battery pack comprising: a housing; a plurality of lithium-based battery cells each of which having an individual state of charge; a charging controller operable to monitor the individual state of' charge of at least one battery cell; and at least one tenninal electrically connectable to a power adapter; wherein the power adapter includes a controlled module to supply a current with accurate charging voltage.
7. The lithium battery pack as set forth in claim 6, wherein the power adapter having a first control terminal, the battery pack having a second control terminal, the first control terminal couples with the second control terminal; and the charging controller transmits a control signal to the controlled module through the first and the second control terminals.
8. The lithium battery pack as set forth in claim 6, wherein charging parameter is determined and transmitted to the controlled module by the charging controller based on the state of the cells and information stored in the battery pack. S 9
9. The lithium batteiy pack as set forth in claim 8, wherein the charging controller includes a sampling circuit for collecting the charging parameter, a batteiy protection circuit, and matching network for outputting a control signal to the controlled module.
10. The lithium battery pack as set forth in claim 6, wherein the controlled module comprises a center controlled module and a feedback module.
11. The lithium battery pack as set forth in claim 6, wherein the charging controller is operable to monitor the state of the individual cell.
12. A lithium battery pack comprising: a housing; a plurality of lithium-based battery cells each of which having an individual state of charge; a charging controller operable to monitor the individual state of charge of at least one battery cell and to control a charging current being supplied to the battery pack based at least in part on the individual state of charge of at least one battery cell; and at least one terminal to electrically connect to a power adapter; wherein the power adapter includes a controlled module to supply a current with accurate charging voltage.
13. The lithium battery pack as set forth in claim 12, wherein charging parameter is determined and transmitted to the controlled module by the charging controller based on the state of the cells and information stored in the battery pack.
14. The lithium battery pack as set forth in claim 13, wherein the information may be stored in an independent location of the battery pack or stored in a MCU.
15. The lithium battery pack as set forth in claim 12, wherein a required charging voltage is supplied by the controlled module with a PWM to control an AC/DC circuit in the power adapter.
16. A lithium battery pack comprising: a housing; a plurality of lithium-based battery cells each of which having an individual state of charge; a charging controller operable to monitor the individual state of charge of at least one battery cell; and at least one terminal for electrically connecting to a power adapter which including a controlled module for supplying a current having an accurate charging voltage; wherein the charging controller includes a charging algorithm and the charging controller implements the charging algorithm in a first charging mode and a second charging mode, and wherein the controller implements one of the first charging mode and the second charging mode based at least in part on the individual state of charge of the at least one battery cell.
17. The lithium battery pack as set forth in claim 16, wherein the charging controller includes a voltage sampling circuit for sensing the individual voltage of the cells; a current sampling circuit for sensing current of the cells; a temperature sampling circuit for sensing temperature of the cells; a matching network for controlling the control signal; and a MCU for controlling the voltage sampling circuit, the current sampling circuit, the temperature sampling circuit and the matching network.
18. The lithium battery pack as set forth in claim 16, further contains a protection circuit.