JP2007240536A - Battery pack and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To send various information to an electronic machine by means of a low-speed-processing microcomputer with saved power. <P>SOLUTION: A CPU 31 collects detection data such as terminal voltage and discharging current of a thermistor 62 and a battery through respective interfaces 38, 37 and 36 every ten seconds, calculates a residual capacity or a total capacity of the battery, stores the results and the collected data as transmission data in a RAM 33, and sends the stored transmission data from a communication interface 39 to the electronic machine not shown at one-second intervals. Since the CPU 31 only transmits the data independently from an operation of a CPU in the electronic machine, an operation clock of the CPU 31 can be remarkably reduced, and also its power consumption can be remarkably reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a battery in which a secondary battery, a control system for performing charge / discharge control of the secondary battery, and a transmission system for transmitting information related to the secondary battery to an electronic device using the secondary battery as a power source are packed together. In particular, the present invention relates to a communication method for transmitting the information.

  Conventionally, the main body of a portable electronic device such as a video camera is a battery pack in which a secondary battery (hereinafter simply referred to as a battery) and a microcomputer for controlling charging / discharging of the battery are integrated. The power supply is detachably mounted. The microcomputer 21 as shown in FIG. 8 in the main body 2 of such an electronic device has a remaining capacity of the secondary battery in the battery pack 1, the number of charge / discharge cycles (charge / discharge cycle), current, voltage, various cautions, etc. An inquiry is made to the microcomputer 11 of the battery pack through the signal line 3 so as to transmit information (data), and the information previously collected by the microcomputer 11 of the battery pack 1 in response to the inquiry is sent to the signal line 3. When it sends it through, it receives this information and performs various processes. Therefore, bidirectional communication is performed between the conventional battery pack 1 and the main body 2 of the electronic device.

  Further, among the processes performed by the microcomputer 11 of the battery pack 1 for collecting the information described above, there is a process for calculating the remaining capacity (remaining capacity) of the secondary battery. In order to calculate this remaining capacity, the microcomputer 11 has a reference table for one discharge curve at no load, and applies current and temperature corrections to the voltage data at the actual load by referring to this reference table. The capacity at the time of no load was calculated and sent to the main body 2 side as Wh (or Ah) information. The main body 2 obtains the remaining capacity as time information by correcting the received no-load capacity and current and temperature.

  Furthermore, when the microcomputer 11 of the battery pack 1 calculates the total capacity (total capacity) after the charge / discharge cycle, the ΔV method is conventionally used. In this method, the current is temporarily turned off during charging, the voltage drop ΔV at that time is read, the battery impedance is calculated, and the total capacity is calculated from the ratio of this result and the initial battery impedance value.

  Further, the microcomputer 11 of the battery pack 1 falls into a state in which the terminal voltage of the battery cannot always be accurately grasped if the voltage of the battery becomes too lower than the normally operable voltage. Conventionally, even if it becomes such a state, the overvoltage control of the battery is performed by detecting the overvoltage of the battery as it is.

  In addition, information indicating the battery status, such as the capacity of a conventional battery pack, is displayed on a display or the like connected to the electronic device after the battery pack is mounted on the electronic device body. It is common to make it.

  As described above, in the bidirectional communication performed between the conventional battery pack 1 and the main body 2 such as an electronic device to which the battery pack 1 is mounted, the battery pack 1 always collects and prepares the latest information, It waits for inquiries on the two sides. In order to respond to such a request, the microcomputer 11 of the battery pack 1 must be capable of high-speed processing (having a high operating clock frequency), so it is not only necessary to use an expensive microcomputer. There is a problem that power consumption also increases. Further, if the main body side does not make an inquiry, information on the battery pack cannot be obtained, and there is a problem that the microcomputer 21 on the main body side is burdened accordingly.

  In addition, since the correction calculation is performed twice in the process of obtaining the remaining capacity of the battery pack, not only is the calculation complicated, but particularly the error in the correction calculation due to temperature is large, so that there is a problem that the calculation accuracy is deteriorated. Moreover, since this remaining capacity is calculated assuming that the current load will continue thereafter, the worst-case remaining capacity when the maximum load is applied is not known, and the battery runs out earlier than the calculated remaining capacity. There was a problem such as panicking.

  Furthermore, in the calculation of the total capacity by the conventional ΔV method, a highly accurate prediction correction is particularly required for the relationship between temperature and internal resistance, and the correction is complicated, so that the accuracy of the calculated total capacity is lowered. There was a problem. Since the prediction correction is also applied to the calculation for obtaining the total capacity after the charge / discharge cycle, there is a problem that the calculation becomes complicated and the calculation accuracy deteriorates.

  Further, when the voltage of the battery is lower than the reference voltage at which the microcomputer 11 can operate, the subsequent overvoltage detection operation of the battery becomes unstable, and the problem that the possibility of overcharging the battery cannot be eliminated. there were.

  In addition, in order to display information indicating the battery status of the battery pack, the user must attach the battery pack to the main body, which not only burdens the user but also checks the status of the battery pack in advance. There was a problem that it was not possible.

  The present invention has been made in view of such circumstances, and a first object of the present invention is to transmit various information to the main body side with a low-speed processing microcomputer and with low power consumption. Is to increase the calculation accuracy of the remaining capacity of the battery and the total capacity of the battery after the number of charge / discharge cycles, its third purpose is to calculate the remaining capacity of the battery at the maximum load, and its fourth purpose is micro Even if the computer becomes unstable due to low voltage, the overcharge detection of the battery is surely performed on the safe side, and the fifth purpose is to burden the user with displaying various data indicating the state of the battery. That is, it can be performed with less power consumption.

  The battery pack of the first aspect of the invention stores a secondary battery that supplies electric power to an electronic device, and a table that stores data for determining the remaining battery capacity in units of time from the terminal voltage of the secondary battery. Storage means, data collection means for collecting terminal voltage data of the secondary battery every first predetermined time, and data in the table in the storage means from the terminal voltage collected by the data collection means Referring to the remaining capacity calculation means for obtaining the remaining battery capacity of the secondary battery in units of time, and the remaining battery capacity calculated by the remaining capacity calculation means is a second shorter than the first predetermined time. Transmitting means for transmitting the electronic device that operates with the secondary battery as a power source at predetermined time intervals in a unidirectional manner independent of control from the electronic device.

  With such a configuration, the remaining battery capacity calculated by the remaining capacity calculating means is transmitted in one direction independently of the control from the electronic device operating with the secondary battery as a power source. In addition, since it is not necessary to match the operation clock of the remaining capacity calculation means with the operation clock of the electronic device, the data collection and transmission processing can be sufficiently performed even with a low-frequency operation clock. Further, the remaining capacity calculating means refers to the table data in the storage means from the terminal voltage data collected by the data collecting means, and calculates the battery capacity in units of the remaining time of the secondary battery a plurality of times. It is obtained without performing the correction calculation.

  The battery pack of the invention of claim 2 is accommodated in the table with respect to terminal voltage data of the secondary battery collected by the data collecting means that is not accommodated in the table. The remaining battery capacity of the secondary battery is obtained by interpolating the stored data.

  With such a configuration, the remaining capacity calculating means performs the interpolation calculation only once for the data of the terminal voltage of the secondary battery collected by the data collecting means not accommodated in the table. Obtain the remaining battery capacity of the next battery.

  The communication method of the invention of claim 3 is a communication method of a battery pack comprising a secondary battery that supplies electric power to an electronic device, and collects terminal voltage data of the secondary battery every first predetermined time, By referring to a table containing data for obtaining the remaining battery capacity from the terminal voltage of the secondary battery in units of time, the remaining battery capacity of the secondary battery can be calculated from the collected terminal voltage. The obtained remaining battery capacity is obtained as a unit from the electronic device to the electronic device operating with the secondary battery as a power source every second predetermined time shorter than the first predetermined time. It is characterized by transmitting in one direction independently of control.

  With such a configuration, the obtained remaining battery capacity can be determined by a protocol based on, for example, a general UART (universal asynchronous receiver / transmitter) independently of a control system of an electronic device that operates using a secondary battery as a power source. Since it is transmitted in one direction, there is no need to synchronize the operation clock for performing transmission and calculation of the remaining battery capacity with the operation clock of the electronic device, and the data collection and transmission processing is sufficient even with a low-frequency operation clock. Done. Further, referring to the table data in the storage means from the collected terminal voltage data, the battery capacity with the remaining time of the secondary battery as a unit is not subjected to multiple prediction calculations or correction calculations. Desired.

  According to a fourth aspect of the present invention, there is provided a battery pack comprising: a secondary battery that supplies electric power to an electronic device; a data collecting unit that collects terminal voltage data of the secondary battery every first predetermined time; and the secondary battery A remaining capacity calculating means for determining the remaining battery capacity from the terminal voltage of the battery; a storage means for storing the maximum load among the number of repetitions of the past n discharges; and the remaining battery determined by the remaining capacity calculating means Correction means for correcting the capacity with the maximum load stored in the storage means to obtain the remaining battery capacity of the secondary battery at the maximum load; and the remaining battery capacity at the maximum load, the first predetermined Transmitting means for transmitting in one direction independent of control from the electronic device to the electronic device operating with the secondary battery as a power source every second predetermined time shorter than the time. Features.

  With such a configuration, the remaining capacity calculating means obtains the remaining battery capacity of the secondary battery, and corrects the obtained battery capacity with the maximum load by the correcting means, thereby remaining the secondary battery at the maximum load. Seeking battery capacity.

  The communication method of the invention of claim 5 is a communication method of a battery pack including a secondary battery for supplying electric power to an electronic device, and collects terminal voltage data of the secondary battery every first predetermined time, After obtaining the remaining battery capacity from the terminal voltage of the secondary battery, the remaining battery capacity is corrected with the maximum load in the past n times of discharge, and the secondary battery at the maximum load is corrected. The remaining battery capacity at the maximum load is determined with respect to the electronic device that operates using the secondary battery as a power source every second predetermined time shorter than the first predetermined time. Transmission is performed in one direction independently of the control from the electronic device.

  With such a configuration, the remaining battery capacity of the secondary battery is obtained, the obtained battery capacity is corrected with the maximum load, and the remaining battery capacity of the secondary battery at the maximum load is obtained.

  The battery pack of the invention of claim 6 has a secondary battery for supplying electric power to an electronic device, and the terminal voltage from the first reference voltage E1V to the second reference voltage E2V when the secondary battery is initially charged. A storage means for storing an initial capacity as a capacity charged in the secondary battery while rising, and an initial total capacity as a total capacity at the time of initial charging of the secondary battery; and at the time of charging the secondary battery Capacity acquisition means for obtaining a capacity charged in the secondary battery while the terminal voltage rises from the first reference voltage E1V to the second reference voltage E2V, and the capacity at every first predetermined time. Calculation means for calculating the current total capacity of the secondary battery from the capacity obtained by the acquisition means and the initial capacity and the initial total capacity stored in the storage means; Total capacity before Transmitting means for transmitting in one direction independent of control from the electronic device to the electronic device operating with the secondary battery as a power source every second predetermined time shorter than the first predetermined time; It is characterized by providing.

  With such a configuration, the capacity acquisition means is a capacity charged in the secondary battery while the terminal voltage rises from the first reference voltage E1V to the second reference voltage E2V when the secondary battery is charged. Ask for. For example, the calculation means calculates the ratio between the capacity obtained by the capacity acquisition means and the initial capacity in the storage means, and multiplies the initial total capacity in the storage means by the current secondary capacity. Calculate the total battery capacity without predictive correction.

  According to a seventh aspect of the present invention, there is provided a communication method for a battery pack including a secondary battery for supplying electric power to an electronic device, wherein the secondary battery is charged from the first reference voltage E1V to the second reference when the secondary battery is initially charged. After preliminarily storing an initial capacity as a capacity charged in the secondary battery while the terminal voltage thereof rises to a voltage E2V, and an initial total capacity as a total capacity at the time of initial charging of the secondary battery, At the time of charging the secondary battery, the capacity charged to the secondary battery while the terminal voltage rises from the first reference voltage E1V to the second reference voltage E2V is determined every first predetermined time, The current total capacity of the secondary battery is calculated from the obtained capacity and the previously stored initial capacity and the initial total capacity, and the current total capacity of the secondary battery is calculated from the first predetermined time. Short second predetermined time To come, and transmits unidirectional independently of the control from the electronic device to the electronic device operating the secondary battery as a power source.

  With such a configuration, the capacity charged in the secondary battery is required while the terminal voltage rises from the first reference voltage E1V to the second reference voltage E2V when the secondary battery is charged. Next, a ratio between the obtained capacity and the initial capacity in the storage means is calculated, and the current total capacity of the secondary battery is predicted and corrected by multiplying the initial total capacity in the storage means by the ratio. Calculated without.

  The battery pack of the invention of claim 8 is a secondary battery for supplying electric power to an electronic device, a data collection means for collecting data relating to the state and charge / discharge of the secondary battery every first predetermined time, What is the control of the data collected by the data collecting means from the electronic device to the electronic device that operates using the secondary battery as a power source every second predetermined time shorter than the first predetermined time? Transmitting means for independently transmitting in one direction, detecting means for detecting the terminal voltage of the secondary battery, and cutting off the charging current to the secondary battery when the terminal voltage of the secondary battery becomes overvoltage And a non-volatile first storage means for storing a first reference voltage for detecting an overvoltage of the secondary battery, and a reference voltage for the collection 2 for detecting an overvoltage of the secondary battery. Volatile second memory hand that remembers And overvoltage of the terminal voltage of the secondary battery detected by the detection means is determined using at least the second reference voltage stored in the second storage means at the normal time, and the 2 When the voltage of the secondary battery decreases and the storage of the second storage unit is erased, the determination is made using the first reference voltage stored in the first storage unit, and the determination result corresponds to And controlling means for controlling the shut-off means to shut off the charging current of the secondary battery.

  With such a configuration, the control unit normally detects at least the second reference voltage stored in the second storage unit as an overvoltage of the terminal voltage of the secondary battery detected by the detection unit. On the other hand, when the voltage of the secondary battery decreases and the storage of the second storage means is erased, the first reference voltage stored in the first storage means is determined. Therefore, if the first reference voltage is set lower than the second reference voltage, the terminal voltage of the secondary battery is set when the memory of the second storage means is erased. An overvoltage is determined at a voltage lower than normal, and the blocking means is controlled to cut off the charging current of the secondary battery early.

  The battery pack of the invention of claim 9 is characterized in that the first reference voltage is substantially lower by a predetermined threshold voltage than a reference voltage for detecting an overvoltage of the secondary battery in a normal state.

  With such a configuration, the control means sets the first reference voltage to an overvoltage with a terminal voltage of the secondary battery lower than a normal voltage when the storage of the second storage means is erased. It judges and controls the said interruption | blocking means and interrupts | blocks the charging current of the said secondary battery early.

  The battery pack of the invention of claim 10 is characterized in that the second reference voltage is the threshold voltage, and the control means detects the overvoltage of the terminal voltage of the secondary battery detected by the detection means at a normal time. A determination is made by comparing the first reference voltage stored in the first storage means with the sum of the threshold voltages stored in the second storage means, and the voltage of the secondary battery decreases. When the memory of the second storage means is erased, the determination is made by comparing with the first reference voltage stored in the first storage means.

  With such a configuration, the control means normally detects the overvoltage of the terminal voltage of the secondary battery detected by the detection means, and the first reference voltage stored in the first storage means at a normal time, When the determination is made by comparing with the sum of the threshold voltages stored in the second storage means, while when the voltage of the secondary battery decreases and the storage of the second storage means is erased, In order to make a determination in comparison with the first reference voltage stored in the first storage unit, when the storage of the second storage unit is erased, the terminal voltage of the secondary battery is set to be higher than normal. If the voltage is too low, it is determined as an overvoltage, and the interruption means is controlled to cut off the charging current of the secondary battery at an early stage.

  In the battery pack according to an eleventh aspect of the invention, the second reference voltage is equal to a sum of the first reference voltage and the threshold voltage, and the control means is configured to detect the secondary battery detected by the detection means. The overvoltage of the terminal voltage is determined by comparing with the second reference voltage stored in the second storage means at a normal time, and the voltage of the secondary battery decreases, and the second memorizing means When the memory is erased, the determination is made by comparing with the first reference voltage stored in the first storage means.

  With such a configuration, the control means uses the second reference voltage stored in the second storage means at the normal time as the overvoltage of the terminal voltage of the secondary battery detected by the detection means. On the other hand, when the voltage of the secondary battery decreases and the storage of the second storage unit is erased, the first reference voltage stored in the first storage unit is used. Therefore, when the storage of the second storage unit is erased, the terminal voltage of the secondary battery is determined to be an overvoltage at a voltage lower than normal, and the blocking unit is controlled to control the secondary battery. Shut off battery charging current early.

  The communication method of the invention of claim 12 is a communication method of a battery pack including a secondary battery for supplying electric power to an electronic device. Data relating to the state and charge / discharge of the secondary battery is obtained every first predetermined time. Collecting the data in one direction independent of control from the electronic device for the electronic device operating with the secondary battery as a power source every second predetermined time shorter than the first predetermined time The first reference voltage for detecting overcharge of the secondary battery is stored in a nonvolatile storage unit, and the second reference voltage for detecting overcharge of the secondary battery is stored. Storing in a volatile storage unit, detecting a terminal voltage of the secondary battery, and determining an overvoltage of the detected terminal voltage of the secondary battery at least using the second reference voltage in a normal state. , The voltage of the secondary battery decreases, the volatile memory When the second reference voltage stored in the memory is erased, the first reference voltage stored in the non-volatile storage unit is used for determination. The charging current of the secondary battery is cut off.

  With such a configuration, the detected overvoltage of the terminal voltage of the secondary battery is normally determined using at least the second reference voltage stored in the second storage unit, When the voltage of the secondary battery decreases and the storage of the second storage unit is erased, the determination is made using the first reference voltage stored in the first storage unit. If the first reference voltage is set lower than the second reference voltage, the terminal voltage of the secondary battery is lower than the normal voltage when the memory of the second storage means is erased. An overvoltage is determined, and the charging current of the secondary battery is cut off early.

  The battery pack of the invention of claim 13 is a secondary battery for supplying electric power to an electronic device, and a data collecting means for collecting data relating to the state and charge / discharge of the secondary battery every first predetermined time, What is the control of the data collected by the data collecting means from the electronic device to the electronic device that operates using the secondary battery as a power source every second predetermined time shorter than the first predetermined time? Transmitting means for independently transmitting in one direction, and display means for displaying information on the secondary battery corresponding to the data collected by the data collecting means.

  With such a configuration, even if the user does nothing, the display unit displays information on the secondary battery corresponding to the state of the secondary battery and the data related to charging / discharging collected by the collecting unit.

  According to a battery pack communication method of a fourteenth aspect of the present invention, in the battery pack communication method including a secondary battery for supplying electric power to an electronic device, the state and charge / discharge of the secondary battery at every first predetermined time. The data from the electronic device is controlled with respect to the electronic device that operates using the secondary battery as a power source every second predetermined time shorter than the first predetermined time. Information related to the secondary battery is displayed in correspondence with the data on a display unit that is independently transmitted in one direction and provided in the battery pack.

  With such a configuration, even if the user does nothing, information on the secondary battery is displayed corresponding to the state of the secondary battery and data related to charging / discharging.

  As described above, according to the first to fourteenth aspects of the present invention, the transmission operation can be performed with low power consumption using an inexpensive microcomputer with low speed processing.

  According to the first and third aspects of the invention, it is possible to further improve the accuracy of the remaining battery capacity in units of the obtained time of the secondary battery.

  According to the invention of claim 2, it is possible to further improve the accuracy of the remaining battery capacity in units of the obtained time of the secondary battery.

  According to the fourth and fifth aspects of the present invention, the user can intuitively grasp the remaining battery capacity of the secondary battery at the maximum load.

  According to the sixth and seventh aspects of the present invention, the calculation for obtaining the current total capacity of the secondary battery can be facilitated and the accuracy can be improved.

  According to the eighth to twelfth aspects of the present invention, because of the low voltage of the secondary battery, the overcharge control of the secondary battery when the volatile memory is volatilized can be reliably performed on the safety side.

  According to the inventions of claims 13 and 14, the user can automatically display the data related to the state of the secondary battery and the charge / discharge on the battery pack at all times, so that the user can install the battery pack in the electronic device. The data can be viewed without burden.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of a battery pack according to the present invention. The microcomputer 51 performs information communication with an electronic device (not shown) corresponding to the main body 2 of FIG. 8, collection and calculation of various information, display of various information, and overvoltage protection. The microcomputer 51 is connected to a secondary battery (hereinafter referred to as a battery) 251 and a terminal voltage detection circuit 53 that detects a terminal voltage of the battery 252. A display unit 54 constituted by an LCD or the like is controlled by the microcomputer 51 and displays the state of the batteries 251 and 252. The breaker 55 finally cuts off the charging / discharging current of the batteries 251 and 252. The output side of the amplifier 57 that amplifies the voltage drop generated in the resistor R32 corresponding to the charging / discharging current of the batteries 251 and 252 is connected to the microcomputer 51. In order to transmit data to the main body side, a data output terminal 59 is provided for outputting data output from the microcomputer 51 to an electronic device. The output of the initial calibration value reading process execution terminal 61 and the output of the thermistor 62 for detecting the temperature in the pack are supplied to the microcomputer 51. The microcomputer 51 forms a secondary protection circuit for the batteries 251 and 252 and operates when the primary protection circuit described later does not operate for some reason to prevent overvoltage or overdischarge of the batteries 251 and 252. To perform the operation.

  The battery control circuit 52 monitors the charging / discharging voltage and current of the batteries 251 and 252 and performs control for preventing overdischarge and overcharge of the batteries by turning on and off the switch circuit 56, and the voltage drop of the resistor R32 The charge / discharge current is detected by the voltage obtained by dividing the voltage by the voltage dividing resistors R1 and R2. The battery control circuit 52 forms a primary protection circuit for the batteries 251 and 252. The switch circuit 56 is configured by connecting two switches formed of FET1 and FET2 in series. In addition, the batteries 251 and 252 connected in series have a positive electrode and a negative electrode connected to battery terminals 58 and 60 that output discharge current to a main body (not shown) or input charging current from a charger (not shown). Yes.

  FIG. 2 is a functional block diagram showing a detailed configuration example of the microcomputer 51 shown in FIG. The CPU 31 performs various operations by executing a program stored in a ROM (first storage means) 32 of a nonvolatile memory using a RAM (second storage means) 33 of a volatile memory as a work memory. As one of these processes, various information is displayed on the display unit 54 via the display control unit 34. The CPU 31 reads the voltage from the amplifier 57 via the charge / discharge current detection interface 36 and reads the terminal voltages of the batteries 251 and 252 via the battery voltage detection interface 37. Further, the CPU 31 reads the temperature in the pack detected by the thermistor 62 via the temperature detection interface 38 and transmits various data from the data output terminal 59 to the electronic device via the communication interface 39. When the CPU 31 detects overcharge based on the terminal voltages of the batteries 251 and 252, it controls the breaker control drive interface 40 to shut off the breaker 55.

  Here, the thermistor 62, the temperature detection interface 38, the resistor R32, the amplifier 57, the charge / discharge current detection interface 36, the battery voltage detection interface 37, and the CPU 31 constitute data collection means or state detection means, and the CPU 31 and the communication interface 39 transmit. Configure the means. The battery voltage detection interface 37 and the CPU 31 constitute measurement means, and the CPU 31 constitutes remaining capacity calculation means, correction means, capacity acquisition means, and calculation means. The CPU 31, the breaker control drive interface 40, and the breaker 55 constitute control means. The CPU 31 and the display control unit 34 or the display unit 54 constitute display means.

  Next, the operation of this embodiment will be described. During the discharging operation, a discharging current flows through the paths of the batteries 252 and 251, the breaker 55, the battery terminal 58, the battery terminal 60, the switch circuit 56, and the resistor R32. The CPU 31 of the microcomputer 51 detects the terminal voltages of the batteries 251 and 252 through the battery voltage detection interface 37 and the temperature in the pack from the thermistor 62 through the temperature detection interface 38. Further, the CPU 31 reads the output voltage of the amplifier 57 by the charge / discharge current detection interface 36 at intervals of 10 seconds and stores it in the RAM 33. The CPU 31 also performs various calculations to be described later using the read data, stores the results as transmission data in the RAM 33 together with the data, and transmits the transmission data from the communication interface 39 to the electronic device as shown in FIG. It is transmitted at 1 second intervals in the communication format.

  FIG. 3 is a diagram showing an example of a communication format created by the communication interface described above. The communication format is made up of 32 bytes as shown in FIG. 3A, and the first two bytes are a start block code as shown in FIG. 3B. The 3rd and 4th bytes are the available time at the current load applied to the battery pack, the 5th and 6th bytes are the available time at the past maximum load, the 7th byte is the relative status of the capacity, The 8th and 9th bytes are the remaining capacity of the batteries 251 and 252, and the 10th byte is the total capacity of the batteries 251 and 252. The eleventh byte is information indicating the state 1 of the battery as described below. (1) End of battery life (60% of initial capacity), (2) 80% of initial capacity, (3) Overcharge, (4) Overdischarge, (5) Over temperature, (6) FET1 (Charge (FET) failure, and (7) FET2 (discharge FET) failure. The twelfth byte is information indicating the state 2 of the battery as described below. That is, (8) charging mode, (9) discharging mode, and (10) battery terminal voltage imbalance (0.5 V or more). The last 4 bits ((10) to (14)) are reserved and free.

  The thirteenth byte is the number of times of charging, the fourteenth byte is the model number, and the fifteenth byte is the lowest voltage of the battery. The 16th byte is the terminal voltage of the battery 251, the 17th byte is the terminal voltage of the battery 252, and the 18th and 19th bytes are the terminal voltage of the battery (not shown) when expanded. The 20th byte is the current flowing through the batteries 251, 252, the 21st byte is the temperature in the current pack, and the 22nd byte is the specification (version). The 23rd to 30th bytes are undefined. The 31st and 32nd bytes are the end block code. It is assumed that the model number, specifications, voltage / current calibration values, etc. are stored in the ROM 32 in advance.

  FIG. 4 is a flowchart showing the data transmission operation processing of the CPU 31 to the electronic device. First, in step 401, the CPU 31 reads and collects data such as voltage, discharge current or temperature of the batteries 251 and 252 and uses these data to overlap the remaining capacity of the batteries 251 and 252 and the number of times of charge and discharge. The calculation for calculating the total capacity of the batteries 251 and 252 is performed. Then, after the transmission data obtained by the calculation is stored in the RAM 33, the process proceeds to step 402, the transmission data is transmitted from the communication interface 39 to the electronic device, and then the process proceeds to step 403.

  The CPU 31 waits for one second after the data is transmitted to the electronic device in step 403. When one second has elapsed, the CPU 31 proceeds to step 404 to send the transmission data in the RAM 33 to the communication interface 39. After transmitting data to the main body, the process proceeds to step 405. In step 405, the CPU 31 determines whether or not 10 seconds have elapsed since the previous data was read and calculated, and if 10 seconds have not elapsed, the process returns to step 403. If 10 seconds have elapsed, the process proceeds to step 406, and various data such as the voltages, discharge currents, and temperatures of the batteries 251 and 252 are read and collected, and the calculation similar to the above is performed using these data, and then the process proceeds to step 403. Return.

  By such communication processing by the CPU 31, data is automatically transmitted to the electronic device every second, and the transmission data is updated every 10 seconds. The format of data transmitted by the communication interface 39 and the type of transmission data are as described with reference to FIG. On the other hand, the CPU on the electronic device side only needs to capture the data transmitted from the battery pack every other second at least once every 10 seconds, and the inquiry for transmitting the data to the battery pack side as in the past. No need.

  Next, a calculation method when the CPU 31 calculates the remaining capacity of the batteries 251 and 252 will be described with reference to FIG. FIG. 5 is a characteristic diagram showing the relationship between the terminal voltage of one battery and the remaining capacity (time) using temperature as a parameter in order to calculate the remaining capacity. The plurality of parameters (in the example, 0.2 C, Characteristic diagrams of four parameters 0.5C, 1C, and 2C (C is a nominal capacity) are stored in advance in the ROM 32 as a reference table. This table is created based on experimental data, and has practically highly accurate values. For example, when the temperature is 0.5 ° C. and the terminal voltage of the battery 251 drops to V4 (in the case of point b), it can be seen that the remaining capacity is 10 minutes. The CPU 31 refers to this table to obtain the remaining capacity and transmits it to the main body side.

  By the way, when it is desired to obtain the remaining capacity at the point e which is not on the characteristic line of the table, the CPU 31 performs the interpolation calculation described below. Here, the length between each point in the figure (hereinafter, the length between the point f and the point e is expressed as fe) is expressed as fe: ec = 1: 4, ad: dk = 2: 3. To do. If it is approximated that the points a, c, and b are on the same straight line, Δakb and Δcjb are similar, and therefore there is a relationship of kb: jb = 5: 3. Since kb = (18-10), jb = (18-10) × 3/5. Therefore, ph = jb + mh = (18−10) × 3/5 + 10 = 14.8.

  Here, the on time that is the remaining capacity at the point e is between the time of qg that is the remaining capacity at the point f (10 minutes) and the time of ph that is the remaining capacity at the point c (14.8 minutes). In addition, the increase in the remaining capacity during this period is considered to be approximately proportional to the horizontal axis direction. Since the increase in the remaining capacity from the point f to the point c is (14.8-10), and the point e is at a position that is 1/5 of the distance to the point c, the point e The increase in the remaining capacity at (14.8-10) × 1/5. Therefore, the on time as the total remaining capacity at this point e is 10+ (14.8-10) × 1/5 = 19.66.

  A characteristic table as shown in FIG. 5 is provided for each temperature, and correction for the temperature is performed in the same manner using the table for each temperature.

  Further, the CPU 31 stores the maximum load during the last three discharges in the RAM 33 from the latest, and corrects the remaining capacity obtained based on the actually measured voltage as described above with the maximum load during the discharge, thereby reducing the minimum load. The remaining capacity is obtained in units of minutes, and the remaining capacity (the shortest usable time) at the maximum load obtained in minutes is transmitted to the main body.

  A calculation method used when the CPU 31 calculates the total capacity after the number of times of charging the batteries 251 and 252 is described with reference to FIG. When the batteries 251 and 252 are repeatedly charged / discharged, the battery deteriorates, and the total capacity (time that can be used immediately after charging) gradually decreases. In other words, the charging characteristic curve rises from A to B as shown in FIG. Therefore, in order to know the state of the battery, it is necessary to obtain the total capacity after the number of charge / discharge cycles. The CPU 31 monitors, for example, the rise of the terminal voltage when charging the battery 251 to a predetermined value within a certain range, and from the time required for the terminal voltage to rise to the predetermined value within this range and the charging current value at that time, The capacity (mAh) charged during this time is obtained, and this is compared with the initial capacity value obtained by performing the same thing first, and the current total capacity is obtained using this comparison value.

  As shown in FIG. 6, the voltage range for monitoring the rise of the terminal voltage is set to a range of 3.7V to 3.9V (predetermined value). First, the initial charging capacity X0 of the battery 251 from 3.7 V to 3.9 V is stored in the ROM 32 for each charging current, and the initial total capacity W0 of the battery 251 is also stored. Here, assuming that the charging current when the number of times of charging is n is in, the charging capacity is Xn, and the charging time is tn, Xn = in × tn. Further, the initial charging capacity X0 at the time of the charging current in is read from the ROM 32. The total capacity Wn when the number of times of charging is n is Wn = W0 × Xn / X0, and the CPU 31 calculates the total capacity Wn every time the number of times of charging is updated, and transmits this to the electronic device body side.

  Further, if the reference voltage for detecting overvoltage (overcharge) with respect to the batteries 251 and 252 is V0, the CPU 31 has a value V1 of (V0−threshold voltage), that is, a predetermined threshold voltage than the reference voltage V0. A value V1 that is lower (for example, 0.5 V) is stored in the ROM 32 in advance. The CPU 12 stores a value obtained by adding 0.5 V to the reference voltage V1 read from the ROM 32, that is, V0V in the RAM 33, and performs normal overcharge detection using the reference voltage V0 in the RAM 33.

  By the way, in order for the microcomputer 51 to operate normally, it is necessary to supply a minimum voltage, and when the battery voltage drops below that, the operation of the microcomputer 51 becomes unstable. If the CPU 31 is reset at a low voltage, the reference voltage V0 in the RAM 33 is also cleared. However, when the reset is performed, that is, when the reference voltage V0 in the RAM 33 is cleared, the CPU 31 subsequently detects the excess of the batteries 251 and 252 based on the 0.5V lower reference voltage V1 in the ROM 32. Perform charge detection. For this reason, the overcharge detection works early by the amount of 0.5 V, and the fuse of the breaker 55 is blown through the breaker control drive interface 40 of FIG. 2 before reaching the reference voltage V0, and the charging current is cut off. The That is, all operations in the battery pack are stopped on the safe side (charging is stopped before the battery is damaged by overcharging).

  Here, unlike the above, the threshold voltage (0.5 V) can be stored in the RAM 33. In this case, the CPU 31 normally uses the reference voltage V0 obtained by adding the threshold voltage (0.5V) stored in the RAM 33 to the reference voltage V1 stored in the ROM 32, and uses the batteries 251 and 252. Overvoltage protection control for these batteries is performed by detecting overvoltage of the terminal voltage. However, when the memory of the RAM 33 is erased due to the low voltage of the batteries 251 and 252, the CPU 31 subsequently detects the overvoltage of the battery using the reference voltage V 1 stored in the ROM 32. The fuse of the breaker 55 is blown, and the entire operation in the battery pack is stopped on the safe side, including itself, as described above.

  FIG. 7 is a plan view showing the outer shape of the battery pack and the display unit 54 formed of an LCD provided on the outer surface of the battery pack. 7A and 7B are a plan view and a side view of the battery pack, and FIG. 7C is an enlarged view of the display portion. A writing unit 71 is provided on the surface of the battery pack so that a user can write a memo with a normal writing tool, and a display unit 54 is provided next to the writing unit 71.

  The CPU 31 displays the capacity on the display unit 351 shown in FIG. 7C of the display unit 54 through the display control unit 34. That is, when the capacity is full, all of the plurality of display portions 351 are turned on, and when the capacity is exhausted, the display is turned off in order from the right side. One of the display units 351 corresponds to a predetermined time such as 10 minutes. Further, during charging, the display unit 352 blinks to indicate that charging is in progress. When the total capacity reaches 60% of the initial value, the display unit 353 is lit to notify that the battery life has been exhausted. Further, every time the number of times of charging exceeds 10, a plurality of display portions 354 are lit and displayed in order from the left to display how much the number of times of charging is.

  According to the present embodiment, the CPU 31 of the battery pack only needs to send data to the main body side every second and update the data once every 10 seconds. In addition, the CPU on the main body side that performs high-speed processing. Since there is no need to prepare transmission data and wait for an inquiry from, the communication operation can be sufficiently performed even if the operation clock is lowered from the conventional 4 MHz to 38.4 kHz. An inexpensive CPU 31 can be used, and the cost of the battery pack can be reduced. Further, since the operation clock of the CPU 31 is lowered, the current supplied to the CPU can be reduced from 4 mA to 7 mA, which was conventionally required, to 30 μA, and the power consumption can be remarkably reduced. Further, the CPU on the main body side only needs to capture the data transmitted from the battery pack side every other second at least once every 10 seconds, and it is not necessary for the battery pack side to make an inquiry for transmitting data as in the prior art. Therefore, no burden is imposed on the process of fetching the data, and other processes can be performed efficiently.

  In addition, by calculating the remaining capacity of the batteries 251 and 252 using an actual measurement value table that plots the relationship between the terminal voltage of the battery and the remaining capacity (time) using a plurality of nominal capacities and temperatures as parameters, Since the remaining capacity from the terminal voltage that is not in the actual measurement table is obtained by interpolation calculation, correction in the calculation process is performed once or at all, so the remaining capacity of the batteries 251 and 252 is reduced. It can be obtained easily and accurately. Furthermore, whether the remaining capacity obtained in this way is corrected by the maximum load in the past three discharges, the remaining capacity at the maximum load is calculated in time units (minutes), and this is transmitted to the main body side and displayed on the main body. Alternatively, since the information is displayed on the display unit 54 of the battery pack, the user can intuitively know how much the batteries 251 and 252 have even in the worst case.

  Furthermore, the total capacity of the batteries 251 and 252 after repeated charging is compared with the capacity charged when, for example, the terminal voltage of the battery 251 during charging rises to a predetermined voltage, and the comparison result. Thus, the remaining capacity of the batteries 251 and 252 can be obtained with higher accuracy than the conventional ΔV method by calibrating the initial total capacity and obtaining the current total capacity.

  In addition, the reference voltage for detecting the overvoltage is stored in the ROM 32 at a low voltage of 0.5V, and this is corrected to a high voltage of 0.5V and stored in the RAM 33 so that the normal overvoltage detection is performed. After the reset and the RAM 33 is cleared, the CPU 31 can detect the overvoltage with the reference voltage of the ROM 32, thereby speeding up the overvoltage detection and stopping the full charging operation of the battery pack on the safe side.

  Further, the CPU 31 always and automatically displays various data related to the state of the battery, such as the battery capacity, the display during charging, the battery life, etc., on the display unit 54, so that these data are always displayed without burdening the user. Can be provided. Further, the data can be displayed without attaching the battery pack to the main body or the charger. Even if the data is always displayed on the display unit 54 as described above, the power consumption of the CPU 31 is reduced, and the display unit 54 is also configured with a low power consumption such as an LCD. Even if consumed, the capacity of the batteries 251 and 252 does not decrease compared to the conventional case due to the constant consumption of the batteries 251 and 252.

It is the functional block diagram which showed the structure of one Embodiment of the battery pack of this invention. FIG. 2 is a functional block diagram illustrating a detailed configuration example of a microcomputer illustrated in FIG. 1. It is the schematic diagram which showed the structural example of the transmission data produced with the communication interface shown in FIG. It is the flowchart which showed the procedure of the communication process of CPU shown in FIG. It is a characteristic view explaining the table value for calculating | requiring the remaining capacity preserve | saved in ROM shown in FIG. It is a characteristic view explaining the calculation method for calculating | requiring the total capacity of the battery after CPU shown in FIG. 2 accumulated the frequency | count of charge. It is the figure which showed the external shape of the battery pack shown in FIG. 1, and the display part provided in the surface. It is a functional block diagram explaining the relationship between the conventional battery pack and a main body.

Explanation of symbols

  31 CPU, 32 ROM, 33 RAM, 34 Display control unit, 36 Charge / discharge current detection interface, 37 Battery voltage detection interface, 38 Temperature detection interface, 39 Communication interface, 40 Breaker control drive interface, 51 Microcomputer, 52 Battery control circuit , 53 terminal voltage detection circuit, 54 display section, 55 breaker, 56 switch circuit, 57 amplifier, 58, 60 battery terminal, 59 data output terminal, 61 initial calibration value read processing execution terminal, 62 thermistor, 251 252 battery

Claims (14)

A secondary battery for supplying power to the electronic device;
Storage means for storing a table containing data for determining the remaining battery capacity in units of time from the terminal voltage of the secondary battery;
Data collecting means for collecting terminal voltage data of the secondary battery every first predetermined time;
A remaining capacity calculating means for obtaining a remaining battery capacity of the secondary battery in units of time by referring to data in a table in the storage means from the terminal voltage collected by the data collecting means;
The remaining battery capacity calculated by the remaining capacity calculating means is sent from the electronic device to the electronic device that operates using the secondary battery as a power source every second predetermined time shorter than the first predetermined time. Transmitting means for transmitting in one direction independently of the control of the battery pack. The remaining capacity calculating means interpolates the data stored in the table by interpolating the data stored in the table with respect to the terminal voltage of the secondary battery collected by the data collecting means not accommodated in the table. The remaining battery capacity of the battery is obtained. In a communication method of a battery pack including a secondary battery that supplies electric power to an electronic device,
Collecting terminal voltage data of the secondary battery every first predetermined time,
By referring to a table containing data for obtaining the remaining battery capacity from the terminal voltage of the secondary battery in units of time, the remaining battery capacity of the secondary battery can be calculated from the collected terminal voltage. As a unit,
The obtained remaining battery capacity is independent of control from the electronic device for the electronic device that operates using the secondary battery as a power source every second predetermined time shorter than the first predetermined time. A communication method characterized by transmitting in one direction. A secondary battery for supplying power to the electronic device;
Data collecting means for collecting terminal voltage data of the secondary battery every first predetermined time;
A remaining capacity calculating means for determining a remaining battery capacity from a terminal voltage of the secondary battery;
Storage means for storing the maximum load among the number of repetitions of the past n discharges;
Correction means for correcting the remaining battery capacity obtained by the remaining capacity calculation means with the maximum load stored in the storage means, and obtaining the remaining battery capacity of the secondary battery at the maximum load;
Control of the remaining battery capacity at the maximum load from the electronic device with respect to the electronic device operating with the secondary battery as a power source every second predetermined time shorter than the first predetermined time. A battery pack comprising: transmission means for independently transmitting in one direction. In a communication method of a battery pack including a secondary battery that supplies electric power to an electronic device,
Collecting terminal voltage data of the secondary battery every first predetermined time,
After obtaining the remaining battery capacity from the terminal voltage of the secondary battery, the remaining battery capacity is corrected with the maximum load in the past n times of discharge, and the secondary battery at the maximum load is corrected. For the remaining battery capacity of
Control of the remaining battery capacity at the maximum load from the electronic device with respect to the electronic device operating with the secondary battery as a power source every second predetermined time shorter than the first predetermined time. A communication method characterized by transmitting independently in one direction. A secondary battery for supplying power to the electronic device;
When the secondary battery is initially charged, an initial capacity as a capacity charged in the secondary battery while the terminal voltage rises from the first reference voltage E1V to the second reference voltage E2V, and the secondary battery Storage means for storing an initial total capacity as a total capacity at the time of initial charging of the battery;
Capacity acquisition means for obtaining a capacity charged in the secondary battery while the terminal voltage rises from the first reference voltage E1V to the second reference voltage E2V when the secondary battery is charged;
Calculation for calculating the current total capacity of the secondary battery from the capacity obtained by the capacity acquisition means and the initial capacity and the initial total capacity stored in the storage means at every first predetermined time. Means,
What is the control of the current total capacity of the secondary battery from the electronic device to the electronic device that operates using the secondary battery as a power source every second predetermined time shorter than the first predetermined time. A battery pack comprising: transmission means for independently transmitting in one direction. In a communication method of a battery pack including a secondary battery that supplies electric power to an electronic device,
When the secondary battery is initially charged, an initial capacity as a capacity charged in the secondary battery while the terminal voltage rises from the first reference voltage E1V to the second reference voltage E2V, and the secondary battery After the initial total capacity as the total capacity at the time of initial charging of the battery is stored in advance, the terminal voltage rises from the first reference voltage E1V to the second reference voltage E2V when the secondary battery is charged. To determine the capacity charged to the secondary battery,
For each first predetermined time, the current total capacity of the secondary battery is calculated from the obtained capacity and the previously stored initial capacity and the initial total capacity,
What is the control of the current total capacity of the secondary battery from the electronic device to the electronic device that operates using the secondary battery as a power source every second predetermined time shorter than the first predetermined time. A communication method characterized by transmitting independently in one direction. A secondary battery for supplying power to the electronic device;
Data collection means for collecting data relating to the state and charge / discharge of the secondary battery every first predetermined time;
What is the control from the electronic device to the electronic device that operates using the secondary battery as a power source every second predetermined time shorter than the first predetermined time, the data collected by the data collecting means A transmission means for independently transmitting in one direction;
Detecting means for detecting a terminal voltage of the secondary battery;
A blocking means for cutting off a charging current to the secondary battery when a terminal voltage of the secondary battery becomes an overvoltage;
Nonvolatile first storage means for storing a first reference voltage for detecting an overvoltage of the secondary battery;
Volatile second storage means for storing a reference voltage of Collection 2 for detecting an overvoltage of the secondary battery;
An overvoltage of the terminal voltage of the secondary battery detected by the detection means is determined using at least the second reference voltage stored in the second storage means at the normal time, and the secondary battery When the voltage stored in the second storage means is erased, the first reference voltage stored in the first storage means is used for determination, and the determination result corresponds to the determination result. A battery pack comprising: control means for controlling the shut-off means to shut off a charging current of the secondary battery. The battery pack according to claim 8, wherein the first reference voltage is substantially lower by a predetermined threshold voltage than a reference voltage for detecting an overvoltage of the secondary battery in a normal state. The second reference voltage is the threshold voltage;
The control means normally detects the overvoltage of the terminal voltage of the secondary battery detected by the detection means, and the first reference voltage stored in the first storage means and the second storage. Judgment is made by comparing with the sum of the threshold voltages stored in the means, and when the voltage of the secondary battery decreases and the memory of the second storage means is erased, the memory is stored in the first storage means The battery pack according to claim 9, wherein the battery pack is determined by comparing with the first reference voltage that is used. The second reference voltage is equal to the sum of the first reference voltage and the threshold voltage,
The control means determines the overvoltage of the terminal voltage of the secondary battery detected by the detection means in comparison with the second reference voltage stored in the second storage means at a normal time, When the voltage of the secondary battery decreases and the storage of the second storage unit is erased, the determination is made by comparing with the first reference voltage stored in the first storage unit. The battery pack according to claim 9. In a communication method of a battery pack including a secondary battery that supplies electric power to an electronic device,
Collecting data relating to the state and charge / discharge of the secondary battery at each first predetermined time,
The data is transmitted unidirectionally to the electronic device that operates using the secondary battery as a power source at a second predetermined time shorter than the first predetermined time, independently of control from the electronic device. And
Storing a first reference voltage for detecting overcharge of the secondary battery in a nonvolatile storage unit;
Storing a second reference voltage for detecting overcharge of the secondary battery in a volatile storage unit;
Detecting the terminal voltage of the secondary battery;
The detected overvoltage of the terminal voltage of the secondary battery is normally determined using at least the second reference voltage, and the voltage of the secondary battery is reduced and stored in the volatile storage unit. When the second reference voltage is erased, the first reference voltage stored in the non-volatile storage unit is used for determination, and in response to the determination result, the secondary battery A communication method characterized by cutting off a charging current. A secondary battery for supplying power to the electronic device;
Data collection means for collecting data relating to the state and charge / discharge of the secondary battery every first predetermined time;
What is the control of the data collected by the data collecting means from the electronic device to the electronic device that operates using the secondary battery as a power source every second predetermined time shorter than the first predetermined time? A transmission means for independently transmitting in one direction;
A battery pack comprising: display means for displaying information relating to the secondary battery corresponding to the data collected by the data collection means. In a communication method of a battery pack provided with a secondary battery for supplying electric power to an electronic device,
Collecting data relating to the state and charge / discharge of the secondary battery at each first predetermined time,
The data is transmitted unidirectionally to the electronic device that operates using the secondary battery as a power source at a second predetermined time shorter than the first predetermined time, independently of control from the electronic device. And the information regarding the said secondary battery is displayed on the display part provided in the said battery pack corresponding to the said data. The communication method characterized by the above-mentioned.

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