JP2010521949A - Fast battery charger apparatus and method - Google Patents

Abstract

  Charging a rechargeable battery having one or more rechargeable cells; determining a current level applied to the battery such that the battery has a predetermined charge that is reached within a specified time period of less than about 15 minutes; Applying a charging current to the battery having a level substantially close to the determined current level.

Description

  With recent developments in storage battery technology, the concept of fast battery charging in minutes rather than hours has become a realistic expectation for consumers. Conventional battery and charger technology requires at least one hour, more typically several hours, to recharge standard Li-Ion and / or NiMH battery packs and accumulators. For many consumer applications, this recharge time often hinders the convenience and usefulness of many devices such as portable DVD players, digital cameras, and video cameras.

  If the user has not planned in advance and has not verified that the device battery is charged and ready to take out, the time to recharge the battery will allow the device to be used when it is needed. Disappear.

  In one aspect, a method of charging a rechargeable battery having one or more rechargeable cells includes a current applied to the battery such that the battery has a predetermined charge that is reached within a specified time period of less than about 15 minutes. Determining a level and applying a charging current to the battery having a level substantially close to the determined current level.

  The following are embodiments within the scope of this aspect.

  The method includes the step of periodically adjusting the charging current after reaching a predetermined voltage level so as to maintain the voltage between the terminals of the battery at a predetermined voltage level. This includes the step of stopping the charging current after a charging time period substantially equal to the specified time period has elapsed. The predetermined charge level of the cell is at least 90% of the charge capacity of the battery, and the specified time period is about 5-15 minutes. The method includes measuring at least one of a voltage across a battery terminal, a battery temperature, and a temperature of a circuit board of a charger device configured to charge the battery, and a voltage level at the battery terminal; Comparing at least one of a battery temperature and a circuit board temperature with a predetermined range of each of the voltage level, the battery temperature level, and the charger device temperature level; and a measured voltage level; And stopping the charging current when at least one of the measured battery temperature and the measured circuit board temperature is outside the respective predetermined range. Applying the charging current having the determined current level includes measuring the applied charging current and adjusting the measured applied charging current to the determined current level. The method includes: a charging device that, from a first insertion position in the charging device, causes the battery terminal to be electrically coupled to the charging device terminal to which a charging current is applied; Moving the battery to a second position. The method includes the step of moving the battery from the second position to the first insertion position by the charger device when the specified time period has elapsed. Applying the charging current to the battery includes applying the charging current to a battery having at least one lithium iron phosphate electrochemical cell.

  In a further aspect, the charger device is configured to charge one or more rechargeable batteries each having at least one rechargeable cell. The apparatus is a charging compartment configured to receive one or more rechargeable batteries, the charging having a terminal configured to be electrically coupled to a respective terminal of the one or more rechargeable batteries. A compartment and a controller, wherein the controller determines a current level applied to the battery to reach a predetermined charge for the battery within a specified time period and is substantially close to the determined current level. A charging current having a level is configured to be applied to the battery.

  The following are embodiments within the scope of this aspect.

  The controller is further configured to periodically adjust the charging current after reaching the predetermined voltage level so as to maintain the voltage between the terminals of the battery at the predetermined voltage level. The controller is further configured to stop the charging current after a charging time period substantially equal to the specified time period has elapsed. The predetermined charge level of the battery is at least 90% of the charge capacity of the battery, and the specified time period is about 5-15 minutes. The apparatus measures a first temperature sensing device configured to measure a first value indicative of a temperature of one or more rechargeable batteries, and a second value indicative of a temperature of a circuit board of the charger device. And a second temperature sensing device configured to calculate a temperature of the one or more rechargeable batteries based on the measured first value and to the measured second value. A circuit board temperature is calculated based on and configured to determine a voltage at one or more rechargeable battery terminals. The controller outputs at least one of a voltage at each terminal of the one or more batteries, a temperature of the one or more batteries, and a temperature of the circuit board, each of the voltage level, the temperature level of the battery, and the temperature level of the circuit board. Any one of the voltage at each terminal of the one or more batteries, the temperature of the one or more batteries, and the temperature of the circuit board is out of the predetermined range. If configured, the charging current is stopped. A controller configured to apply a charging current having a determined current level is configured to measure the applied charging current and adjust the measured applied charging current to the determined current level Is done. The device includes a mechanism configured to move one or more batteries from an initial position on the charger device into the charging compartment. The moving mechanism is configured to move one or more batteries from the charging compartment to the first insertion position when the specified time period has elapsed. The device includes one or more batteries. The one or more batteries include one or more batteries having at least one lithium iron phosphate electrochemical cell. The controller includes a processor based microcontroller.

  One or more of the aspects described above may include one or more of the following advantages.

  The ability to charge batteries in minutes instead of hours eliminates the need for users to plan ahead, making it more convenient to use a large number of portable devices, as well as something more voluntary. Become.

  Other features and advantages of the invention will be apparent from the description and from the claims.

1 is a block diagram of an exemplary embodiment of a fast charger. The circuit diagram of the charger of FIG. 1 is a representative embodiment of an AC / DC converter. 6 is a flowchart of an exemplary embodiment of a charger validation procedure. 6 is a flowchart of an exemplary embodiment of a charging procedure. The flowchart of one typical embodiment of the procedure after charge.

  FIG. 1 shows a charger 10 configured to charge a rechargeable battery 12 having at least one rechargeable cell. The battery 12 is received in a charging container or compartment (not shown). In some embodiments, battery 12 includes a graphite anode material or a lithium titanate anode material and a lithiated iron phosphate cathode material for fast recharging of rechargeable batteries based on such materials. Includes a Li-Ion cell adapted to enable. The charger 10 sets the current level applied to the rechargeable battery 12 to reach a predetermined charge (eg, 90% capacity) of the battery 12 within a specified time period, typically less than 15 minutes. Is configured to determine. Although FIG. 1 shows a single battery 12, the charger 10 may be adapted to accept and charge two or more rechargeable batteries simultaneously.

  The charger 10 is connected to the power conversion module 14. The power conversion module 14 includes an AC / DC converter 16 that is electrically coupled to an AC power supply external to the charger, such as a power supply that supplies power with standards of 85 V to 265 V and 50 Hz to 60 Hz, and has low DC power. Converted to a voltage (eg, 5-24V), for example, this low DC voltage is supplied to, for example, the DC-DC converter 20 to a level suitable for charging the rechargeable battery (eg, Li-Ion described above). In the case of a cell, a DC voltage at a level of about 3.7-4.2 V. Other types of cells may have different voltage levels). The AC / DC converter 16 may be implemented as an isolated AC / DC switching device configured to accept input power of a first alternating voltage and transform it into a lower constant DC voltage. An exemplary embodiment of an AC / DC switching device 50 is shown in FIG. The AC / DC converter prevents the input AC current from reaching the DC output portion of the AC / DC converter 16 and protects the user from accidental exposure to the AC current to provide an AC input line and DC output. Including galvanic insulation between.

  The AC / DC converter 16 also adjusts the DC output voltage of the converter 16 so that a substantially constant voltage level is supplied on the output side of the converter, regardless of the load current obtained from the supply. Includes a feedback mechanism (not shown).

  In some embodiments, an additional DC-DC converter 18 is incorporated into the power conversion module 14 to provide an external DC power source, such as an automotive DC power source, to a DC power level suitable for charging a rechargeable battery. Convert to For example, in some embodiments, the automotive DC power source provides approximately 11.5V to 14.3V DC power, and the DC-DC converter 18 converts the power level to the charge controller 20 and the charge converter. Convert 30 to a suitable power level acceptable for charging. Other power conversion configurations may also be used. The added DC-DC converter can be configured to accept almost any DC power source, for example in the range of 1.2V to about 24V, when the converter 18 is of a buck / boost configuration. If the converter is a buck converter, the minimum DC input source is greater than the minimum voltage required to power the charge controller and charge the battery, typically 5.5V or 6V. Should be.

  The charger 10 determines the charging current applied to the rechargeable battery 12 such that the battery 12 is charged to a charge capacity of, for example, at least 90% in less than 15 minutes. For example, lithium iron phosphate electrochemical cell-based batteries generally exhibit low internal charging resistance during the charging operation, and therefore should be charged with a relatively large charging current, for example, on the order of 4C-15C. In this case, the current of 4C is a current required to charge the rechargeable battery in 15 minutes (1C is a current required to charge a specific rechargeable battery in 1 hour), and 15C Is the current required to charge the rechargeable battery in 4 minutes. Due to the low charging resistance of lithium iron phosphate batteries, significant heat dissipation is avoided, and thus such batteries can withstand high charging currents without adversely affecting battery performance or durability. In some embodiments, the charger 10 is configured to output a constant current of 2400 mA or 12 C at 4 V or less, so that the charger has a capacity of 200 mAh (“Ah” is ampere, for example, in about 5 minutes). High rate Li-Ion cells (sometimes the equivalent unit) can be fully charged to over 90% of the total capacity.

  The charger 10 determines a charging current applied to the battery 12, applies a current substantially equal to the determined charging current to the battery 12, and charges after a specified or predetermined time period has elapsed. A controller 20 is configured to stop the current. The controller 10 may also be configured to stop the charging current when a predetermined battery voltage or charge is reached. In some embodiments, the charge controller 20 adjusts the buck converter 30 to apply a constant 12C charge rate until a predetermined maximum charge voltage is reached, or until, for example, a 5 minute time period has passed. . When the maximum charging voltage is reached, the charging controller 20 changes the control mode and applies a constant voltage to the storage battery 12 until a predetermined charging time, for example, 5 minutes has passed.

  The determination of the charging current applied to the battery 12 may be based, at least in part, on user-specified input provided via a user interface (not shown) located on the charger 10. Such a user interface may include, for example, switches, buttons, and / or knobs through which the user is associated with the type of battery to be recharged, the charging period, and / or the charging process. Other types of parameters may be indicated. To determine the specific charging current to use, a look-up table is accessed that shows the preferred charging current corresponding to the user specified parameters. For example, if the user specifies that the lithium iron phosphate battery is to be recharged and further specifies a 5 minute charge deadline, specify a charge current suitable for charging the lithium iron phosphate battery at that time. , The corresponding entry in the lookup table is used. In some embodiments, computational techniques may be used to determine an appropriate charging current.

  In some embodiments, the determination of the charging current identifies the battery (s) located within the charging compartment of the charger 10 using, for example, an identification mechanism that provides data regarding the characteristics of the battery 12. Or by measuring battery characteristics indicating the type of battery to be recharged (eg, battery charge resistance). A detailed description of a typical charger device that adaptively determines the charging current based on measured battery characteristics can be found in a co-pending application entitled “Adaptive Charger Device and Method” The entire contents of which are incorporated herein by reference.

  The user interface may also include input elements (eg, switches) that enable or disable the charger 10. When such a switch is switched, the controller 20 receives a corresponding signal, for example, via the associated ENABLE terminal 20a (see FIG. 2). The user interface may also include an output device such as an LED for providing the user with status information regarding the charger and / or battery 12 connected thereto, a display device configured to provide the output information to the user, and the like. Good. In this example, the user interface is, for example, a red LED that lights when a fault condition such as an overvoltage or overheat fault condition occurs, and a yellow or green LED device that indicates that the charging operation of the battery 12 is in progress, for example. including.

  The controller 20 includes a processor device 22 configured to control a charging operation performed on the battery 12 as will be described later. The processor unit 22 may be any type of computing and / or processing unit such as a PIC18F1320 microcontroller manufactured by Microchip Technology Inc. The processor device 22 used to implement the controller 10 includes volatile and / or non-volatile memory elements configured to store software including computer instructions that allow general operation of the processor-based device, And a charging operation that achieves at least 90% charge capacity in less than 15 minutes, and a charging operation, such as detecting a fault condition and preventing or stopping the charging operation under such circumstances, is connected to the charger. An implementation program for the battery 12 may be mentioned.

  The processor 22 includes an analog to digital (A / D) converter 24 having a plurality of analog and digital input and output lines. The A / D converter 24 is configured to receive a signal from a sensor (described below) coupled to the battery to facilitate adjustment and control of the charging operation. In some embodiments, the controller 20 may also include a digital signal processor (DSP) to perform some or all of the processing functions of the controller as described herein.

  The controller 20 also includes a digital-to-analog (D / A) converter device 26 and / or a pulse width modulator (PWM) 28 that receives a digital signal generated by the processor device 22. In response, an electrical signal is generated that adjusts the duty cycle of a switching network, such as the buck converter 30 of the charger 10.

  The controller module including the processor 22, the A / D converter 24, the D / A converter 26, and / or the PWM 28 may be disposed on a circuit board (not shown) of the charger 10.

  In some embodiments, charger 10 includes a battery, such as battery 12, such that the terminal of the battery is in electrical communication with the charging terminal of charger 10 when a charging current is applied to the battery. An automatic loading / discharging mechanism (not shown) may be included that automatically moves from a first insertion position on the charger 10 to a second position within the charging compartment of the charger. At the end of the charging operation, the charger 10 causes the automatic loading / discharging mechanism to discharge the batteries, thereby moving the batteries from their second position to their insertion position. Such a load / discharge mechanism includes a motor and a motor drive control circuit that may be part of the controller 20 to control the load / discharge operation of the mechanism and enable or disable motor drive power. The loading / discharging mechanism provides a mechanical user interface that can be loaded, charged and removed with minimal user action. A detailed description of a typical loading / discharging mechanism can be found in the co-pending patent entitled “Battery Charger with Mechanism to Automatically Load and Eject Batteries”. Provided in the application, the entire contents of which are incorporated herein by reference.

  FIG. 2 shows two bipolar junction transistors (BJT) 32 and 34 and stores energy when the power conversion module 14 is in electrical communication with the buck converter 30, and the power conversion module 14 is a buck converter. A buck converter 30 is shown that includes an inductor 36 that discharges its energy as a current during a period of electrical isolation from 30. The buck converter 30 shown in FIG. 2 also includes a capacitor 38 that is also used as an energy storage element. The inductor 36 and the capacitor 38 also function as an output filter that reduces switching current and voltage ripples on the output side of the buck converter 30.

  The power transferred from the power conversion module 14 to the battery 12 is adjusted by controlling the voltage level applied to the bases of the transistors 32 and 34. An operating electrical signal from terminal 20d of controller 20 (designated SW1) is applied to the base of transistor 32 so that power from power conversion module 14 is applied to the terminal of battery 12. A current flow from the power conversion module 14 to the transistor 32 and the battery 12 is obtained. The charger 10 also performs signal filtering and processing on analog and / or digital input signals to provide inaccurate measurements (eg, voltage, temperature, etc.) that may be caused by external factors such as circuit level noise. Signal conditioning blocks such as filters 44 and 45 may be included to prevent (accurate measurement).

  When the operating signal applied to the base of transistor 32 is withdrawn, current flow from power conversion module 14 stops and inductor 36 supplies current from the energy stored therein. During the off period of transistor 32, a second operating signal is applied to the base of transistor 34 by terminal 20e of controller 20 (designated SW2), allowing current to flow through battery 12 (transistor 32's Use energy stored in inductor 36 and / or capacitor 38 during the on period). In some embodiments, instead of transistor 34, a rectifier diode that provides similar functionality as transistor 34 is used.

  The on period of the transistor, i.e. the duty cycle, initially increases from 0% duty cycle, during which the controller or feedback loop measures the output current and voltage. When the determined charging current is reached, the feedback control loop manages the duty cycle of the transistor using a closed loop linear feedback scheme, for example using a proportional integral derivative (PID) mechanism. A similar control mechanism may be used to control the duty cycle of the transistor once the voltage output of the charger, i.e. the battery terminal voltage, has reached the crossover voltage.

  Accordingly, the current supplied by the power conversion module 14 during the on period of the transistor 32 and the current supplied by the inductor 36 and / or capacitor 38 during the off period of the transistor 32 substantially reduce the required charging current. Equivalent effective currents should be obtained.

  In some embodiments, the controller 20 periodically receives a measurement of the current flowing through the battery 12, as measured by the current sensor 42, for example, every 0.1 seconds. Based on the received measured current, the controller 20 adjusts the duty cycle to adjust the current so that the current through the battery 12 converges to a value substantially equal to the charge current level. In this way, the buck converter 30 is configured to operate with an adjustable duty cycle, thereby providing an adjustable current level that is supplied to the battery 12.

  As described, the charger 10 includes sensors configured to collect data and communicate it to a controller to easily control charging and general operations performed by the charger 10. The charger 10 includes a voltage sensor 40 (designated VSENSE) and a current sensor 42 (designated ISENSE) in electrical communication with the charging terminal of the charger 10 in the charging compartment. When the battery 12 is inserted into the charging compartment and the battery terminals are in electrical contact with the charger terminals, the sensors 40 and 42 are in electrical communication with the battery terminals and the voltage of the battery 12 And the current can be measured, and the measurement data is transmitted to the controller 20.

  As described in more detail below, based on the voltage at the terminals of the battery 12 and / or the current flowing through the battery 12, there is a fault condition where the controller needs to stop the charging operation or not start the charging operation. Judge whether to do. For example, the controller 20 determines whether the voltage measured by the voltage sensor 40 at the terminal of the battery 12 is within a predetermined voltage level range (for example, 2 to 3.8 V) with respect to the battery 12. Can do. If the measured value is below the lower limit of the voltage range, this may indicate that the battery is defective. If the measured value is above the upper limit of the range, this may indicate that the battery is already fully charged and therefore no further charging is necessary and may damage the battery. Therefore, if the measured voltage is not within the predetermined range, a fault condition is considered to exist.

  The charger may make a similar determination regarding the current measured by the current sensor 42, and if the measured current is outside the predetermined current range, a fault condition is considered to exist and, as a result, The charging operation is not started or stopped.

  The charger 10 further includes a sensor configured to measure the battery 12 and / or other attributes of the charger 10. For example, the charger includes a temperature sensor configured to be coupled to the battery 12 and / or to a circuit board on which the controller 20 is disposed. A suitable temperature sensor is a sensor realized using a thermistor whose resistance varies with temperature. Therefore, for example, the controller 20 includes a temperature sensor, measures the temperature of the circuit board, and determines whether the measured temperature exceeds a specific threshold (for example, 60 ° C.). If so, this may indicate that the charger may be overheated and a fault condition is considered to exist, so that the charging operation is stopped, or Not started.

  In some embodiments, other types of repair operations may be performed once the presence of a fault condition is determined. For example, in a situation where the controller 20 determines that the circuit board or battery 12 of the charger is overheated, the controller 20 reduces the charging current applied to the battery 12 and thereby the temperature of the battery 12 or circuit board. May be reduced.

  In some embodiments, the received measurement signal includes analog logic, such as a dedicated charge controller device, that determines the level of voltage and current measured by sensors 40 and / or 42, including, for example, a threshold comparator. Processed using processing elements (not shown). The charger 10 also includes a signal conditioning block (not shown) that performs signal filtering and processing on analog and / or digital input signals, which may be caused by external factors such as circuit level noise. Measurement (eg, inaccurate measurement of voltage, temperature, etc.) may be prevented.

  The controller 20 is configured to maintain the voltage at the terminals of the battery 12 near a substantially constant upper limit value once it reaches a predetermined voltage upper limit value. While the battery 12 is being substantially charged by the charging current, the voltage at the battery terminals increases. To ensure that the voltage at the battery terminals does not exceed a predetermined voltage limit (so that the battery does not overheat or otherwise affect the battery's operation or expected life) The voltages at the 12 terminals are measured periodically (eg, every 0.1 seconds) using the voltage sensor 40 to determine when a predetermined upper limit has been reached. When the voltage at the battery 12 terminal reaches a predetermined voltage upper limit, the current / voltage regulation circuit is controlled so that the voltage at the battery 12 terminal is substantially constant (such behavior). The device to be realized is sometimes referred to as a constant current / constant voltage (CC / CV) device).

  In some embodiments, the controller 20 is also applied to the battery 12 to periodically measure the voltage at the terminals of the battery 12 and to reach a predetermined voltage upper limit within some specified voltage rise time. The voltage increase rate may be monitored by adjusting the charging current. The charging current level is adjusted based on the measured voltage increase rate so as to reach a predetermined voltage upper limit value within a specified voltage rise time period, thereby increasing or decreasing the charging current. The adjustment of the charging current level may be performed according to a predictor corrector technique using a Kalman filter, for example. Other strategies for determining the adjustment of the current to achieve a predetermined voltage upper limit may be used.

  Thus, during the constant current phase, the controller 20 controls the buck converter 30 so that the current is substantially equal to the charge current level applied to the battery 12. When the upper voltage limit is reached, an approximate new due cycle value is determined (eg, by using a look-up table) and the buck converter 30 is controlled accordingly. Thereafter, the controller 20 appropriately adjusts the duty cycle of the signal for operating the transistor 32 so that the voltage at the battery terminal substantially converges to the constant voltage upper limit value by the feedback mechanism.

  4-6 show an exemplary embodiment of the procedure performed in the series of operations of the charger 10.

  FIG. 4 shows a charger enablement procedure 60 that prepares the charger 10 for charging operation of two batteries, such as the battery 12 shown in FIGS. 1 and 2, received within the charging compartment of the charger. . As shown, charger 10 performs several charger setup operations (62). In order to prevent the charging operation from starting early prior to the various pre-charge checks that need to be completed among the operations performed, the charger 10 (e.g., electrically connects the output terminals 20d and 20e of the controller 20 to Is disabled). In addition, a switch detection operation is performed to determine the switch position of the user interface located on the charger 10 and thereby determine the desired charging profile for the user. For example, a switch on the charger user interface can indicate a desired charging time for recharging the rechargeable battery 12, the battery type of the battery connected to the charger, and the like. Further, a port of the charger 10 is configured. For example, ports connected to various external sensors such as temperature sensors, battery voltage sensors, etc. are identified and appropriate interface procedures (eg, filtering, A / D conversion) corresponding to such identified sensors are performed. May be.

The charger 10 measures the voltage at the terminal of the battery electrically coupled to the charger 10 (64). In this example, two voltage measurements V _cell1 and V _cell2 are made, corresponding to the two batteries received in the charging compartment of the charger. In addition, the charger 10 measures the temperature of the board of the charger 10 to confirm that the charger is not overheated. Other measurements of charger and / or battery operating conditions may be made.

Once the battery voltage and / or charger board temperature is measured, the charger determines if the measurement is within a pre-specified range (66). In particular, the charger 10 determines whether both batteries are within the expected voltage range. For example, rechargeable batteries that are used and depleted typically have a battery voltage of 2 to 3.8V. If the battery has a voltage higher than 3.8V, this is not only that the battery is actually fully charged and therefore it is not necessary to recharge such a battery, it actually damages the battery. May indicate that it can. If the battery has a voltage lower than 2V, this may indicate that the battery is damaged and therefore should not be recharged. Therefore, in a situation where it is determined that voltage V _cell1 or V _cell2 is outside an allowable pre-specified voltage range, charger 10 determines that a fault condition exists.

  Similarly, if the measured temperature of the charger 10 board is determined to be higher than some pre-specified temperature threshold, eg, 60 ° C., therefore, the temperature of the charger 10 is too high, indicating that it cannot be used safely. The charger 10 determines that a fault condition exists.

  In situations where it is determined that a fault condition exists, the charger activates the corresponding user interface indicator (68). For example, the charger 10 lights a red LED disposed on the charger 10 to indicate to the user that a fault condition exists in this way. In some embodiments, the user interface may include multiple LEDs, each associated with a different cause of the fault condition, thus providing the user with more accurate information regarding the cause or origin of the fault condition. it can. After the red LED is lit, the charger may wait for a specific time period (eg, 20 seconds) so that the user can clear the fault. For example, if the fault condition is due to a battery defect (eg, if the corresponding measured voltage of the battery is less than 2V), the user can remove the battery and / or the battery functions normally. Can be inserted in place. Under some circumstances, the fault condition may be cleared without user intervention (for example, if the charger board temperature is too high, the temperature will drop without any action on the part of the user). May be good).

  The charger repeats the determination of whether a fault condition exists until all the causes of the fault condition are cleared. When all fault conditions are cleared, the charger 10 is ready for use (70) and the recharge operation can proceed. In addition, the charger activates the corresponding user interface indicator. For example, charge-enabled operation may be indicated by blinking a yellow LED. Furthermore, if a red LED indicating a failure has already been lit, the LED is turned off to indicate to the user that there is no fault condition now.

  FIG. 5 illustrates an exemplary embodiment of a charging procedure 80 performed by the charger 10 during recharging of the rechargeable battery (ie, after the charger is enabled at 70 in FIG. 4). The charger 10 starts a timer to measure a charging time period in which a current substantially equal to the charging current is applied to the rechargeable battery (82). The timer may be, for example, a dedicated timer module of the processor 22 or a counter that is incremented at regular time intervals measured by an internal or external clock of the processor 22.

  The charger 10 applies the determined charging current to the battery (84). As described herein, the charging current applied to the battery is determined based on information specified by the user through a user interface located on the charger 10. Such information includes charge rate (eg, 4C, 15C, etc.) or time limit, battery type (the charger is mechanically and / or electrically configured to charge multiple types of batteries. In the case of the embodiment). This information can be used to determine the charge applied to the battery, for example, using a look-up table that correlates input provided by the user to the corresponding charge current, or by performing one or more computational techniques to determine the charge current. Used to calculate current. The determined charging current is used to generate an electrical signal, for example by DAC or PWM, to activate the transistors 32 and 34 of the buck converter 30.

  During the charging operation, the charger 10 determines whether a fault condition relating to the charger and / or battery has occurred. Thus, for example, the charger 10 determines whether the voltage of one of the batteries exceeds a predetermined voltage upper limit value (for example, 4 V) (86). This determination is based on a periodic measurement (85) of the voltage at the terminals of each battery being charged by the charger 10. If the voltage at any battery terminal exceeds its upper voltage limit while the battery is charging, this may indicate that the battery whose voltage exceeds the upper limit value is overheated, and thus this fault condition. This may indicate that repair work may need to be performed. Accordingly, the charger 10 turns on the red LED indicating that a fault condition exists (92), and as a result disables the controller to stop the charging current applied to the battery (94). Also, the timer used to measure the charging time is reset (96).

  Similarly, the charger also determines whether the board temperature exceeds a predetermined upper temperature limit (eg, 60 ° C.), which is also periodically measured by the charger 10 (85) (88). If so, the charger 10 turns on the red LED on the user interface (92), disables the charger 10 (94), and resets the timer (96). The charger may determine whether another type of fault condition exists.

  If there is no fault condition, the charger will indicate whether a charging time limit (eg, 5 minutes) has elapsed to charge the rechargeable battery, which can be specified by the user via the user interface of the charger 10. Judgment is made (90). If the charging time has not elapsed, the charger 10 repeats the battery voltage and board temperature measurements (85) to determine if a fault condition exists (86 and 88), and the charging time has elapsed. It is determined whether it has been (90). This series of operations may be repeated after a short delay (for example, 1 to 5 seconds).

  When the charging time has elapsed, the charger 10 blinks the yellow LED (91), disables the charger 10 (94), and resets the timer (96). In some embodiments, the charging operation may be stopped when the battery reaches some predetermined voltage level or some predetermined charge level.

  Optionally, the voltage increase rate of either battery may be measured periodically to reach a predetermined voltage upper limit within a specified voltage rise time period (98). The charging current level is adjusted based on the measured voltage increase rate so that the predetermined voltage upper limit value is reached within the specified voltage rise time limit (the operation applied to the current / voltage adjustment circuit correspondingly) Increase or decrease the charging current (by adjusting the signal). As described herein, adjustment of the charging current level may be performed according to a predictor corrector technique such as a Kalman filter or some other similar strategy.

  FIG. 6 shows the charging performed by the charger 10 after the charger 10 is disabled due to the occurrence of a fault condition or after the charging operation has ended and the timer has been reset. An exemplary embodiment of post-procedure 100 is shown. In some embodiments, the user manually removes the battery from the charging compartment of the charger 10. Optionally, if the charger includes an automatic loading / discharging mechanism, the charger may cause the battery to be discharged by that mechanism (102). Under these circumstances, the charger 10 moves the battery from the charging position to the insertion position by the automatic loading / discharging mechanism.

To ensure that the battery has been removed from the charging compartment of charger 10, a voltage sensor on the charger, such as voltage sensor 40, measures the voltage at the charging terminal of the charger (104). If the battery is still in the charging compartment, the measured voltage is in a range typical of the voltage at the battery terminals (eg, 2-3.8V). However, if the battery is removed and the charging compartment is empty, the voltage measured by the sensor is usually zero. In order to take into account any voltage leakage from the power conversion module 14 and to add some measurement tolerances, a measured voltage below 1V at the charging terminal is considered to indicate that the charging compartment is empty. It is. Accordingly, the charger 10 determines whether the voltages V _cell1 and V _cell2 measured at the charging terminal are both less than 1 V (106). If both voltages are less than 1V, the charger 10 turns off the yellow LED on the user interface of the charger 10 (108), indicating that the battery has been removed from the charging compartment. The charger 10 waits for further input from the user specifying the next charging operation (110).

  On the other hand, if one of the charging terminal voltages is 1 V or higher, the charger 10 repeats the measurement (104) of the charging terminal voltage, and all the measured voltages are below the voltage level indicating that the charging section is empty. Determine whether. The measurement (104) may be repeated after a short delay (eg, 1-5 seconds).

Other Embodiments A number of embodiments of the invention have been described. However, it will be understood that various modifications can be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the claims.

Claims (10)

Determining a current level applied to the battery such that the battery has a predetermined charge that is reached within a specified time period of less than about 15 minutes;
Applying a charging current to the battery having a level substantially close to the determined current level;
Charging a rechargeable battery having one or more rechargeable cells.   The method further comprises the step of periodically adjusting the charging current after reaching the predetermined voltage level so as to maintain the voltage between the terminals of the battery at a predetermined voltage level. The method described in 1.   The method of claim 1, further comprising stopping the charging current after a charging time period substantially equal to the designated time period has elapsed.   The method of claim 1, wherein the predetermined charge level of the cell is at least 90% of the charge capacity of the battery and the specified time period is about 5 to 15 minutes. Measuring at least one of a voltage between terminals of the battery, a temperature of the battery, and a temperature of a circuit board of a charger device configured to charge the battery;
At least one of a voltage level at the terminal of the battery, the temperature of the battery, and the temperature of the circuit board, and a predetermined range of each of the voltage level, the battery temperature level, and the charger device temperature level; A step of comparing;
The charging current is stopped if at least one of the measured voltage level, the measured battery temperature, and the measured circuit board temperature is outside the respective predetermined range. The method of claim 1, further comprising: Applying the charging current having the determined current level comprises:
Measuring the applied charging current;
Adjusting the measured applied charging current to the determined current level.   The charger device causes the battery device to be electrically coupled to a terminal of the charger device to which the charging current is applied, from a first insertion position in the charger device by the charger device. The method of claim 1, further comprising moving the battery to a second position.   8. The method of claim 7, further comprising moving the battery from the second position to the first insertion position by the charger device when the specified time period has elapsed.   The method of claim 1, wherein applying the charging current to the battery comprises applying the charging current to a battery having at least one lithium iron phosphate electrochemical cell. A charging compartment configured to receive the one or more rechargeable batteries, the charging compartment having terminals configured to be electrically coupled to respective terminals of the one or more rechargeable batteries. When,
A controller, and
The controller is
Determining a current level applied to the battery to reach a predetermined charge for the battery within a specified time period;
Configured to apply a charging current to the battery having a level substantially close to the determined current level;
A charger device configured to charge one or more rechargeable batteries each having at least one rechargeable cell.

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