Patent Publication Number: US-2007096692-A1

Title: Electric power storage device with multiple voltage outputs

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention is related to an electric power storage device with multiple voltage outputs, and more particularly to an electric power storage device that can provide electricity of various voltages for different electronic devices.  
      2. Description of Related Art  
      Over the last 40 years computers have spread across the world becoming firstly an essential part of any office or workplace and now a commonplace item in most households throughout the developed world. They now provide a vast range of functions and are increasingly compact. Moreover, computer technologies are still progressing at a rapid rate. Personal computers, such as portable computers, notebook computers, and palm computers, are now becoming more and more common. Because small-scale computers are usually used without connecting to a municipal electrical grid, they need to obtain their electric supply from dry batteries or rechargeable batteries. Obviously, most notebook computers are equipped with rechargeable batteries because they can be used repeatedly.  
      Reference is made to  FIG. 1 , which is a schematic diagram of a conventional computer. When in use, the computer  10  obtains electricity from a rechargeable battery (not shown). The rechargeable battery connects to a plug  30  via an alternative current (AC) adapter  20  and obtains electricity from the municipal electrical grid thereby.  
      Reference is also made to  FIG. 2 , which is a block diagram of a conventional computer charging system. In the conventional computer charging system, AC adapter  20  coverts AC electricity from the municipal electrical grid into direct current (DC) electricity. A microprocessor  104  is connected respectively to AC adapter  20  and the rechargeable battery  108 . The microprocessor  104  is used to check the power level of the rechargeable battery  108 . If the power level of the rechargeable battery  108  is lower than a bottom threshold, the microprocessor  104  sends a charge-enable signal to the charging circuit  106 . At this time, the charging circuit  106  uses the electricity from the municipal electrical grid to charge the rechargeable battery  108 . When the power level of the rechargeable battery  108  reaches a top threshold, the microprocessor  104  sends a charge-disable signal to the charging circuit  106  to stop the charging operation.  
      In reference to the description above, since computers in the market have different voltage requirements, they should be equipped with specific AC adapters for charging their rechargeable batteries. It is inconvenient in use. Moreover, the electrical capacity of rechargeable batteries is finite. Without being charged by electricity from the municipal electrical grid through AC adapters, the electricity from rechargeable batteries runs out quickly. Once the electricity of the rechargeable batteries runs out, a computer is forced to shut down. Hence, when in use, the computers are unstable without a supply of electricity from the municipal electrical grid.  
      Accordingly, as discussed above, the prior art still has some drawbacks that could be improved upon. The present invention aims to resolve the drawbacks of the prior art.  
     SUMMARY OF THE INVENTION  
      An objective of the present invention is to provide an electric power storage device with multiple voltage outputs, used to output various voltage levels for different electronic devices. The present invention can also provide electricity for rechargeable batteries of electronic devices when the electronic devices are used in an environment where electricity from the municipal electrical grid is unavailable.  
      For achieving the objective above, the present invention provides an electric power storage device with multiple voltage outputs. The device of the present invention is connected respectively to an alternative current (AC) adapter and an electronic device. The electric power storage device is used to receive direct current (DC) electricity from AC adapter and provide the voltage outputs to the electronic device. The electric power storage device of the present invention includes a first switch connecting to the electronic device; a second switch connecting to the electronic device; a voltage level-adjusting unit used to output a setting signal of a selected voltage level; a processing unit connecting respectively to the first switch, the second switch, and the voltage level-adjusting unit to receive DC electricity and the setting signal of the selected voltage level to switch on/off the first switch and the second switch after comparisons and operations; a charging circuit using DC electricity to charge the a battery unit; and a voltage transformer connecting respectively to the processing unit, the battery unit, and the second switch to transform electricity obtained from the battery unit under a control of the processing unit and provide the transformed electricity for the electronic device via the second switch.  
      For achieving the objective above, the present invention provides another electric power storage device with multiple voltage outputs. The electric power storage device receives DC electricity and provides the voltage outputs to an electronic device. The electric power storage device of the present invention includes a first switch connecting to the electronic device; a second switch connecting to the electronic device; a voltage level-adjusting unit used to output a setting signal of a selected voltage level; a processing unit connecting respectively to the first switch, the second switch, and the voltage level-adjusting unit to receive DC electricity and the setting signal of the selected voltage level to switch on/off the first switch and the second switch after comparisons and operations; and a voltage transformer connecting respectively to the processing unit, the second switch, and a battery unit to transform electricity obtained from the battery unit under a control of the processing unit and provide the transformed electricity for the electronic device via the second switch.  
      Numerous additional features, benefits and details of the present invention are described in the detailed description, which follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The foregoing aspects and many of the attendant advantages of this invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
       FIG. 1  is a schematic diagram of a conventional computer;  
       FIG. 2  is a block diagram of a conventional computer charging system;  
       FIG. 3  is a schematic diagram of the present invention;  
       FIG. 4  is a block diagram of the present invention; and  
       FIG. 5  is a circuit diagram of the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
      Reference is made to  FIG. 3 , which is a schematic diagram of the present invention. In the present invention, an electric power storage device  60  with multiple voltage outputs is provided. The electric power storage device  60  connects respectively to an AC adapter  50  and an electronic device  40 . It receives DC electricity from AC adapter  50 , which converts AC electricity from the municipal electrical grid obtained from a plug  70  into DC electricity. Due to operations of the internal circuit, the electric power storage device  60  can provide multiple voltage outputs to the electronic device  40 .  
      Reference is made to  FIG. 4 , which is a block diagram of the present invention. The present invention connects respectively to an AC adapter  50  and an electronic device  40 . It receives DC electricity and provides multiple voltage outputs to the electronic device  40 . The present invention has a first switch  601  connecting respectively to the electronic device  40  and the AC adapter  50 ; a second switch  602  connects to the electronic device  40 ; a voltage level-adjusting unit  604  is used to output a setting signal of a selected voltage level; a processing unit  603  connects respectively to the first switch  601 , the second switch  602 , and the voltage level-adjusting unit  604  to receive DC electricity and the setting signal of the selected voltage level and to switch on/off the first switch  601  and the second switch  602  after some comparisons and operations; a charging circuit  608  that uses DC electricity to charge the battery unit  605 ; and a voltage transformer  607  connects respectively to the processing unit  603 , the battery unit  605 , and the second switch  602  to transform electricity obtained from the battery unit  605  under the control of the processing unit  603  and provide it to the electronic device  40  via the second switch  602 .  
      As shown in  FIG. 4 , the present invention further has a battery management unit  606  connecting respectively to the processing unit  603  and the battery unit  605 . The battery management unit  606  obtains the status information of the battery unit  605  and passes it to the processing unit. In addition, the battery management unit  606  can be used to control the electric current outputted to the electronic device  40  according to the setting signal issued from the voltage level-adjusting unit  604  to provide dynamic overload protection. Therein, dynamic overload protection is performed by the processing unit  603 , which executes a program to obtain the voltage level of the battery unit  605  and then change the amount of the outputted electric current accordingly. The present invention further has a short-circuit protection/recovery unit  609  connecting respectively to the first switch  601  and the second switch  602  for restriction of the output voltage when a short circuit occurs and for recovering normal operations as well.  
      Reference is made to  FIG. 4  together with  FIG. 5 , which is a circuit diagram of the present invention. In the present invention, the processing unit  603  (PSOC chip) is connected to an AC adapter via two resistors R 7  and R 8 , which are used for voltage division. Thereby, according to the principle of voltage division, the processing unit  603  can obtain DC electricity provided from the AC adapter  50 . The processing unit  603  (PSOC chip) firstly measures the voltage level of DC electricity obtained externally and then compares it with the selected voltage level of the voltage level-adjusting unit  604 . If the two voltage levels are the same, the processing unit  603  uses its output end SW_ACIN to issue a signal to switch on the MOSFET switches Q 11  and Q 12 . At this time, DC electricity is provided for the charging circuit  608  to simultaneously charge the battery unit  605  and the electronic device  40 .  
      In the description above, if the voltage level of DC electricity is not the same as the selected voltage level of the voltage level-adjusting unit  604 , the processing unit  603  uses the output end SW_ACIN to issue a signal to switch off the MOSFET switches Q 11  and Q 12 . At this time, DC electricity is only provided to charge the battery unit  605 . In this way, the electricity with incorrect voltage will not be outputted to the electronic device  40 . Thus, the electronic device  40  is protected from being damaged.  
      Please refer to  FIG. 5 . Suppose that the voltage of DC electricity outputted from AC adapter  50  is 15V. The voltage of DC electricity is first divided by the resistors R 7  and R 8  and then passed to the processing unit  603  to be compared with the selected voltage level of the voltage level-adjusting unit  604 . At this time, if the selected voltage level of the voltage level-adjusting unit  604  is also 15V, the processing unit  603  uses its output end SW_ACIN to issue a signal to switch on the MOSFET switches Q 11  and Q 12  of the first switch  601 . At this time, DC electricity obtained from the AD adapter  50  is provided to the electronic device  40  via the output end V_FINALOUT. Otherwise, the processing unit  603  uses the output end SW_ACIN to switch off the MOSFET switches Q 11  and Q 12 . At this time, DC electricity is only provided to charge the battery unit  605 . In this way, electricity of an incorrect voltage will not be outputted to the electronic device  40 . Thus, the electronic device  40  is protected from being damaged.  
      Please refer to  FIG. 5  again. When DC electricity outputted from AC adapter  50  is cut off, the device of the present invention starts discharging electricity, instead of being charged. At this time, the output end SW_ACIN of the processing unit  603  maintains a low voltage, but the output end SW_OUT is used to send a signal to switch on the MOSET switches Q 7  and Q 8  of the second switch  602 . At this time, the battery unit  605  provides electricity of a correct voltage to the electronic device  40  via the voltage transformer  607  together with the MOSET switches Q 7  and Q 8 . Similarly, the processing unit  603  will compare the voltage level of the electricity outputted from the voltage transformer  607  with the selected voltage level of the voltage level-adjusting unit  604 . If these two voltage levels are not the same or the voltage level of the voltage level-adjusting unit  604  is changed during the electricity discharging duration, the processing unit  603  keeps the output end SW_OUT with low voltage to switch off the MOSET switches Q 7  and Q 8 . In this situation, the output end V_FINALOUT will not provide electricity of the required voltage to the electronic device  40 .  
      In the description above, if the voltage level of the voltage level-adjusting unit  604  is recovered to the original level and the signal transmission line located between the present invention&#39;s device and the electronic device  40  is inserted again, a detecting pin of the processing unit  603  will receive a reset signal. At this time, the processing unit  603  will perform the voltage level comparison operation again. If the voltage level of the electricity outputted from the voltage transformer  607  is the same as the selected voltage level of the voltage level-adjusting unit  604 , the processing unit  603  will control its output end SW_VOUT to switch on the MOSFET switches Q 7  and Q 8 . Thereby, electricity is provided to the electronic device  40  via the output end V_FINALOUT. Otherwise, if the voltage level of the electricity outputted from the voltage transformer  607  is different from the selected voltage level of the voltage level-adjusting unit  604 , the MOSFET switches Q 7  and Q 8  will be switched off until the two voltage levels are adjusted to the same level.  
      Please refer to  FIG. 5  again. The present invention further has a protection function that can recover normal operations automatically after a short circuit occurs at the output end. This function is performed by the short-circuit protection/recovery unit  609 , which connects respectively to the first switch  601  and the second switch  602 . The short-circuit protection/recovery unit  609  comprises a diode D 16 . When a short circuit occurs, the voltage of the output end V_FINALOUT drops to a low level. Since the diode D 16  is forward biased, the output end V_FINALOUT with a low voltage level makes voltages of the output ends SW_ACIN and SW_VOUT drop to a low level. Thus, the MOSFET switches Q 7  and Q 8  or the MOSFET switches Q 11  and Q 12  are switched off to isolate the present invention&#39;s device from the electronic device  40  so that the electronic device  40  is protected from being damaged. Moreover, when the condition that caused the short circuit is removed, the normal voltage levels of the output ends SW_ACIN and SW_VOUT are recovered due to the separation provided by the reverse-biased diode D 16 . Thus, the MOSFET switches Q 7  and Q 8  or the MOSFET switches Q 11  and Q 12  are switched on again. In this way, the connection between the present invention&#39;s device and the electronic device  40  is recovered.  
      Conventionally, short-circuit protection is provided by using fuse wires. Although fuse wires can be used to provide short-circuit protection, they cannot be recovered automatically once they have been fused. On the contrary, the short-circuit protection function of the present invention can be recovered automatically due to its hardware circuit.  
      Please refer to  FIG. 5  again. The present invention also has an output overload protection function. According to the selected voltage level of the voltage level-adjusting unit  604 , the device of the present invention restricts the output power by using the current value provided by the battery management unit  606 . In conditions in which the output power is fixed, when the output voltage alters, the input current should be changed accordingly to provide dynamic overload protection.  
      For example, according to the law of the conservation of energy, input power must equal output power, which can be expressed as: 
 
 P out= P in= V out* I out= V in* I in.  (1) 
 
      Suppose that the maximum output power Pout is restricted to 100 W, the output voltage is Vout=24V, the output current is Iout=4.16 A, and the input voltage is Vin=16V. Hence, the equation (1) can be rewritten as: 
 
 P out=100 W=24V*4.16 A=16V* I in. 
 
      After calculation, we can obtain that Iin=6.25 A. Hence, the input current should be restricted to 6.25 A. When the input voltage Vin (voltage of the battery) drops to 12V, according to equation (1), we have 
 
 P out=100 W=24V*4.16 A=12V* I in. 
 
 After calculation, we can obtain that Iin=8.33 A. Hence, the restriction of the input current should be changed to 8.33 A. 
 
      The present invention provides the output overload protection function by using the processing unit  603  to execute a program. Due to the execution of the program, the processing unit  603  can read the voltage value of the battery unit  605  via the battery management unit  606  (i.e. BQ2060 IC) for calculation of the value of input current. Then, the processing unit  603  changes the restriction of input current according to the calculation result to provide the output overload protection function.  
      To sum up, the present invention uses the processing unit  603  to memorize the value of the voltage inputted externally and check whether the input voltage level is the same as the selected voltage level of the voltage level-adjusting unit  604 . If these two voltage levels are the same, the electricity inputted externally can be passed to the electronic device  40  directly and used to charge the device of the present invention. If the external electric power supply is removed, the device of the present invention outputs electricity according to the selected voltage level of the voltage level-adjusting unit  604 . However, if the input voltage of the external electric power supply does not equal the selected voltage level of the voltage level-adjusting unit  604  when the external electric power supply inputs electricity to the device of the present invention, the device of the present invention is not allowed to output electricity when the external electric power supply is removed.  
      Furthermore, when the voltage level of the voltage level-adjusting unit  604  is selected, it can be confirmed by unplugging/plugging an external connection wire. Then, the device of the present invention starts to provide electricity. However, if the voltage level of the voltage level-adjusting unit  604  is changed in the electricity output duration, the device of the present invention will not output electricity until the external connection wire is unplugged and plugged in again. When the voltage level-adjusting unit  604  is turned off or the external connection wire is removed, the device of the present invention enters a sleep mode to save electricity.  
      Although the present invention has been described with reference to the preferred embodiments thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are embraced within the scope of the invention as defined in the appended claims.