JP2014117054A - Charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging device capable of appropriately selecting a threshold voltage for discriminating overdischarge according to a rated voltage of a battery pack when selectively charging a plurality of battery packs having different rated voltages.
A charging device includes a charging means capable of selectively charging battery packs having different rated voltages, an identification means for identifying a rated voltage of a battery pack to be charged, and a battery voltage of the battery pack to be charged. And detecting means for determining whether or not the battery pack is below the discharge limit voltage based on a signal from the detecting means. The determination means defines a plurality of threshold voltages having different values, and selects one of the plurality of threshold voltages according to the rated voltage of the battery pack identified by the identification means for determination.
[Selection] Figure 1

Description

  The present invention relates to a charging device capable of selectively charging battery packs having different rated voltages.

  Cordless power tools are used in a variety of sizes, shapes, and powers in accordance with the variety of uses. Secondary battery packs used for cordless power tools also have various rated outputs according to the tool body. Voltage and capacity are provided. In addition, as a charging device for charging these battery packs, a multi-type charging device corresponding to a plurality of rated voltage battery packs is also widely used to specify the type of battery provided in the battery pack. Charging is performed at a charging voltage corresponding to the connected battery pack using a resistor or the like (see Patent Document 1).

JP 2009-178012 A

  In recent battery packs, in order to meet the demand for higher output and larger capacity (longer working time), high-performance secondary batteries such as lithium-ion batteries have been adopted one after another. These high-performance secondary batteries generally have strict charge / discharge conditions to ensure the secondary battery's capacity, life, etc., and charge voltage set based on the rated voltage. It is necessary to pay attention not only to the voltage at which charging ends, but also to the state and voltage of the battery at the start of charging. Further, in the above-described multi-charger, unlike a dedicated battery charger that is specialized for a specific battery pack and charging conditions are determined, it is possible to determine the state of a plurality of battery packs and perform charging according to the battery pack. is necessary.

  In view of such circumstances, an object of the present invention is a charging device capable of selectively charging a plurality of battery packs having different rated voltages, and appropriately determining the state and voltage of the battery at the start of charging of the battery pack. An object of the present invention is to provide a charging device that performs charging under suitable charging conditions.

  The charging device of the present invention is connected to the charging means capable of selectively charging battery packs having different rated voltages, the identification means for identifying the rated voltage of the battery pack connected to the charging means, and the charging means. Detection means for detecting a battery voltage of the battery pack, and determination means for determining whether or not the battery pack connected to the charging means is equal to or lower than a discharge limit voltage based on a signal from the detection means. A plurality of threshold voltages having different values are defined, and the determination unit selects one of the plurality of threshold voltages according to a rated voltage of the battery pack identified by the identification unit. The determination is performed.

  With the above configuration, the threshold voltage for determining whether or not the battery pack is equal to or lower than the discharge limit voltage can be changed according to the rated voltage of the battery pack to be charged. Accordingly, it is possible to appropriately determine whether or not the battery voltage of the battery pack is equal to or lower than the discharge limit voltage.

  Preferably, the discrimination means has two threshold voltages. Preferably, the determination means has at least three threshold voltages. With the above configuration, it is possible to appropriately select a threshold voltage for determining whether or not the battery pack is equal to or lower than the discharge limit voltage according to the magnitude of the rated voltage of the battery pack.

  Preferably, the determination unit includes a Zener diode corresponding to each of the threshold voltages. Therefore, it is possible to determine whether or not the battery pack is below the discharge limit voltage with a simple circuit configuration.

  Preferably, the charging device includes a logical operation circuit, and the determination unit compares the threshold voltage with the battery voltage by the logical operation circuit. Therefore, it is possible to determine whether or not the battery pack is below the discharge limit voltage with a simple circuit configuration.

  Preferably, the battery pack further includes a control unit that controls the charging unit, and when the determining unit determines that the battery pack is equal to or lower than the discharge limit voltage, the control unit includes the battery pack by the charging unit. Do not charge. That is, when it is determined that the battery pack to be charged is equal to or lower than the discharge limit voltage, the battery pack is not charged, and the life of the battery pack can be prevented from being shortened.

  Preferably, the battery pack further includes a control unit that controls the charging unit, and when the determination unit determines that the battery pack is equal to or lower than the discharge limit voltage, the control unit uses the charging unit to control the battery pack. Precharge. That is, when it is determined that the battery pack to be charged is equal to or lower than the discharge limit voltage, the battery pack is precharged, so that the life of the battery pack can be prevented from being shortened.

  Preferably, the determination means detects a signal generated when the battery pack is fully charged or overdischarged to determine the state of the battery pack. In addition to detecting the battery voltage of the battery pack, the battery voltage status of the battery pack is monitored based on the signal emitted by the battery pack. Therefore, the battery voltage status of the battery pack is more accurately grasped and charging control is performed. It can be carried out.

  Preferably, the battery pack includes a battery cell made of a lithium ion battery. Therefore, appropriate charge control can be performed on the lithium ion battery in an overdischarged state.

  According to the present invention, when the charging device selectively charges battery packs having different rated voltages, it determines whether or not the battery pack is equal to or lower than the discharge limit voltage according to the rated voltage of the battery pack. Since the threshold voltage is selected, it is possible to appropriately determine whether or not the battery pack is in an overdischarged state.

The block diagram which shows the structure of the charging device by the 1st Embodiment of this invention. The flowchart which shows charge of the battery pack by the charging device shown in FIG. The block diagram which shows the structure of the charging device by the 2nd Embodiment of this invention. The flowchart which shows charge of the battery pack by the charging device shown in FIG. The flowchart which shows the modification of charge of the battery pack by the charging device shown in FIG. The block diagram which shows the structure of the charging device by the 3rd Embodiment of this invention. The flowchart which shows charge of the battery pack by the charging device shown in FIG. The block diagram which shows the structure of the charging device by the 4th Embodiment of this invention. The flowchart which shows charge of the battery pack by the charging device shown in FIG.

(First embodiment)
Hereinafter, a charging device 1 according to an embodiment of the present invention and a battery pack 2 attached to the charging device 1 will be described with reference to the accompanying drawings. FIG. 1 is a circuit diagram showing a state where a battery pack 2 is attached to the charging device 1. The battery pack 2 is used as a power source for a cordless tool (not shown).

  First, the battery pack 2 to be charged will be described. As shown in FIG. 1, the battery pack 2 includes a battery set formed by connecting a plurality of battery cells 2a in series, a battery type discrimination resistor 7, a thermistor 8 as a temperature sensing element, and a protection IC 2b. ing. In the present embodiment, the battery pack 2 having a built-in lithium ion battery is to be charged. The battery type discrimination resistor 7 has a resistance value according to the type of the battery pack 2 (the rated voltage of the battery pack 2, the battery type and number of battery cells connected in series, etc.), and the resistance value. Thus, the number of battery cells 2a connected in series can be known. The thermistor 8 is arranged in contact with or close to the battery set, and detects the temperature of the battery set. The protection IC 2b is for monitoring the voltage of each battery cell 2a and preventing any one of them from being overdischarged or overcharged. As the battery is charged, the voltage of the battery cell 2b increases. Charging is continued and a signal is output from the protection IC 2b when a threshold voltage (charging limit voltage) at which full charging is reached is reached. The protection IC 2b also outputs a signal when at least one of the battery cells 2a has dropped to a threshold voltage (discharge limit voltage) that may cause overdischarge. As an example, the protection IC 2b outputs a high signal at a normal use voltage when the battery pack 2 is neither overdischarged or fully charged, and informs the user of overdischarge or full charge. A low signal is output.

  The battery pack 2 has terminals corresponding to a plus terminal and a minus terminal for charging provided in the charging apparatus 1, a temperature detection terminal, and a battery type information input terminal. When the battery pack 2 is attached to the charging apparatus 1, These corresponding terminals are connected.

  Next, the charging device 1 will be described. The charging device 1 includes a power supply unit, a microcomputer 50, various detection units connected to an input port of the microcomputer 50, a controlled unit connected to an output port of the microcomputer 50, and the like.

  The power supply unit includes a main power supply for supplying charging power and an auxiliary power supply for supplying a drive voltage to the microcomputer 50 and the like. The main power source is a power source for charging the battery pack 2, and includes a first rectifying / smoothing circuit 10, a switching circuit 20, and a second rectifying / smoothing circuit 30.

  The first rectifying / smoothing circuit 10 includes a full-wave rectifying circuit 11 and a smoothing capacitor 12. The AC voltage supplied from the AC power supply 13 is full-wave rectified by the full-wave rectifying circuit 11 and smoothed by the smoothing capacitor 12. Output a DC voltage. The AC power source 13 is an external power source such as a commercial power source.

  The switching circuit 20 is connected to the output side of the first rectifying / smoothing circuit 10 and includes a high-frequency transformer 21, an FET 22, and a PWM control IC 23. The PWM control IC 23 changes the drive pulse width of the FET 22, and the FET 22 performs switching according to the drive pulse width, and uses the DC output from the first rectifying and smoothing circuit 10 as the voltage of the pulse train waveform. The voltage of the pulse train waveform is applied to the primary side winding of the high-frequency transformer 21, boosted (or stepped down) by the high-frequency transformer 21, and output to the second rectifying and smoothing circuit 30.

  The second rectifying / smoothing circuit 30 includes a diode 31, a smoothing capacitor 32, and a discharging resistor 33. The second rectifying / smoothing circuit 30 rectifies and smoothes the output voltage obtained from the secondary side of the high-frequency transformer 21 to generate a DC voltage, The DC voltage is output from the positive terminal and the negative terminal of the charging device 1. The main power supply, the first rectifying / smoothing circuit 10, the switching circuit 20, and the second rectifying / smoothing circuit 30 constitute charging means.

  The auxiliary power supply 40 is connected to the first rectifying / smoothing circuit 10 and the switching circuit 20 and supplied with power, and is a constant voltage power supply for supplying a stabilized power supply voltage Vcc to various circuits such as the microcomputer 50 and operational amplifiers 61 and 65 described later. Circuit. The auxiliary power supply 40 includes transformers 41a and 41b, a switching element 42, a control element 43, a rectifier diode 44, a three-terminal regulator 46, oscillation prevention capacitors 45 and 47, and a reset IC 48. The reset IC 48 is an IC that outputs a reset signal to the microcomputer 50 when the charging apparatus 1 is connected to an AC power source.

  The rectifying / smoothing circuit 6 is a rectifying / smoothing circuit that is connected to the auxiliary power supply 40, the switching circuit 20, and the like and serves as a power supply for the PWM control IC 23. The rectifying / smoothing circuit 6 includes a secondary coil 6a, a rectifier diode 6b, and a smoothing capacitor 6c of the transformer 41a. .

  The microcomputer 50 includes a first output port 51a, a second output port 51b, an A / D input port 52, a reset port 53, and the like as control means. The microcomputer 50 processes various signals input to the A / D input port 52, and outputs various signals based on the results from the first output port 51a and the second output port 51b to various controlled units. The operation of the charging device 1 is controlled.

  The charging current setting circuit 70 is connected to the first output port 51b, and the charging current control circuit 60 is connected to the A / D input port 52.

  The charging current setting circuit 70 is composed of resistors 71 and 72 connected in series between the power supply voltage Vcc and the ground, and is a circuit for setting the charging current to a predetermined current value. A connection point between the resistor 71 and the resistor 72 is connected to a non-inverting input terminal of an operational amplifier 66 constituting the charge control circuit 60.

  In the present embodiment, the charging current setting circuit 70 selectively sets two types of current values I1 and I2 as setting currents for charging. Specifically, when the output port 51b outputs a high signal, a value obtained by dividing the power supply voltage Vcc by the resistors 71 and 72 is a reference value for setting the set current as the current value I1. In the present embodiment, the charging current value I1 is 3A as an example.

  Further, when the second output port 51b connected to the resistor 73 outputs a low signal, the value obtained by dividing the power supply voltage Vcc by the resistor 71 and the parallel resistance of the resistors 72 and 73 becomes the set current as the current value I2. It becomes a reference value when setting as. The charging current I2 is smaller than the charging current I1, and is 1A as an example in the present embodiment.

  As described above, the charging current control circuit 60 is connected to the charging current setting circuit 70 and controls the charging current based on the setting by the charging current setting circuit 70. The charging current control circuit 60 includes operational amplifiers 61 and 65, resistors 62, 63, 64, 66 and 67, and a diode 68.

  The current detection resistor 3 is connected between the second rectifying / smoothing circuit 30 and the charging voltage control circuit 100 and detects a charging current flowing through the battery pack 2.

  A battery type discrimination circuit 9, a battery temperature detection circuit 80, and a battery voltage detection circuit 90 are connected to the A / D input port 52 of the microcomputer 50.

  The battery temperature detection circuit 80 includes resistors 81 and 82 connected in series to a power supply voltage Vcc and a reference potential (GND). A connection point between the resistors 81 and 82 is connected to the thermistor 8 and a microcomputer. 50 A / D input ports 52 are connected. When the temperature of the battery set changes, a voltage value associated with the temperature change is applied to the A / D input port 52 of the microcomputer 50. Thereby, the temperature of the thermistor 8 can be specified.

  The battery voltage detection circuit 90 is connected to the positive terminal of the battery set and includes resistors 91 and 92 in a state where the battery pack 2 is mounted on the charging device 1 as detection means. The voltage supplied to the battery pack 2, that is, the voltage of the battery pack 2 is divided by the resistors 91 and 92, and the value is input to the A / D input port 52 of the microcomputer 50 as battery voltage information. In the present invention, the battery voltage refers to a battery voltage actually detected from the battery pack 2 or a numerical value determined to have a one-to-one correspondence with the actual battery voltage.

  The battery type determination circuit 9 includes a reference resistance element 9a having one end connected to the power supply voltage Vcc as identification means. When the battery pack 2 is attached to the battery type determination circuit 9, the battery type determination resistor 7 and the reference resistance element 9a are connected in series. Since the divided voltage value of the power supply voltage Vcc by the resistor 9d and the battery type discriminating resistor 7 is input to the microcomputer 50, the microcomputer 50 determines the type (rated voltage, Number of battery cells connected in series).

  The charge control signal transmission unit 4 and the display unit 120 are connected to the first output port 51 a of the microcomputer 50. A charging voltage control circuit 100 is connected to the second output port 51b of the microcomputer 50. A constant voltage power supply circuit 40 is connected to the reset port 53.

  The charge control signal transmission unit 4 is connected to the switching circuit 20 and the microcomputer 50, etc., and is connected to the photocoupler 4 that transmits a signal for controlling on / off of the PWM control circuit 23, and the light emitting element side that constitutes the photocoupler 4. The FET 4a controls the on / off of the light emitting element. The gate of the FET 4a is connected to the first output port 51a via the diode 4b. When the output port 51a outputs a high signal, the FET 4a is turned on and the photocoupler 4 is turned on. As a result, the PWM control circuit 23 is activated and charging is started. When the output port 51a outputs a low signal, the FET 4a is turned off and the photocoupler 4 is turned off. As a result, the PWM control circuit 23 is stopped and charging is completed. Further, when the FET 210 of the threshold voltage setting circuit 25, which will be described in detail later, is turned on, the high signal output from the output port 51a is not input to the FET 4a but is grounded via the diode 4c and the FET 218. First, the photocoupler 4 is turned off. Therefore, the PWM control circuit 23 is stopped and charging is finished.

  The charging current signal transmission unit 5 is connected to the switching circuit 20, the charging voltage control circuit 100, the charging current control circuit 60, and the like, and includes a photocoupler that feeds back a charging current signal to the PWM control IC 23.

  The display unit 120 is a circuit for displaying a charging state, and includes an LED 121 and resistors 122 and 123. When the first output port 51a connected to the resistor 122 outputs a high signal, the LED 121 lights red, and when the first output port 51a connected to the resistor 123 outputs a high signal, the LED 121 lights green. When a high signal is output from both ports, the LED 121 is lit in orange. In the present embodiment, the microcomputer 50 lights the LED 121 in red before charging, lights the LED 121 in orange during charging, and lights the LED 121 in green after charging.

  The charging voltage control circuit 100 is connected to the second rectifying / smoothing circuit 30 and controls the charging voltage. The charging voltage control circuit 100 includes resistors 101, 102, 103, 105, 106, 107, 108, potentiometer 102, FET 109, capacitor 104, shunt regulator 112, and rectifier diode 111. Based on the signal from the second output port 51 b of the microcomputer 50, the charge voltage is obtained by dividing the divided value of the resistor 101, the series resistor of the potentiometer 102, and the parallel resistor of the resistor 105 and the resistor 106 with the reference value of the shunt regulator 112. It is determined to be.

  The threshold voltage setting circuit 25 uses a threshold voltage that is a discharge limit voltage for determining an overdischarge state according to a rated voltage of the battery pack 2 attached to the charging device 1 as a determination unit, and has a different breakdown voltage (Zener voltage). In this example, two Zener diodes are adopted and set, and the presence or absence of an overdischarge state of the battery pack 2 is determined from the battery voltage. The threshold voltage setting circuit 25 includes an operational amplifier 220, resistors 200, 203, 206, 207, 209, 211, 212, FETs 208, 210, 213, Zener diodes 201, 204, and diodes 202, 205.

  The threshold voltage setting circuit 25 is a circuit provided between the reference potential and the node A using the battery voltage of the battery pack 2 as an input voltage. As a path corresponding to the first threshold voltage, a resistor 200, a Zener diode 201, a diode 202, and a resistor 207 are connected in series from the high potential side between the node A and the reference potential. The Zener diode 201 has a cathode connected to the resistor 200 and an anode connected to the anode of the diode 202. The Zener voltage V1 of the Zener diode 201 is, for example, a value corresponding to the discharge limit threshold voltage of the battery pack 2 when the battery pack 2 is formed by connecting five battery cells in series. In this embodiment, the Zener voltage V1 is 9V, for example. is there.

  Further, the threshold voltage setting circuit 25 has a high path as a path corresponding to the second threshold voltage in parallel with the path for the first threshold voltage between the node A and the high potential side terminal of the resistor 207. In order from the potential side, a resistor 203, a Zener diode 204, and a diode 205 are connected in series. The Zener diode 204 has a cathode connected to the resistor 203 and an anode connected to the anode of the diode 205. Note that the Zener voltage V4 of the Zener diode 204 has a value higher than the Zener voltage of the Zener diode 201. For example, when the battery pack 2 is formed by connecting ten battery cells in series, the discharge limit threshold of the battery pack 2 is reached. The value corresponding to the voltage is 18V.

  Further, a resistor 206 and an FET 208 are connected in series between the power supply voltage Vcc and the reference potential. The FET 208 has a drain connected to the resistor 206, a source connected to the reference potential, and a gate connected to a connection point between the diode 205 and the resistor 207.

  The FET 210 has a drain connected as an output of the threshold voltage setting circuit 25 to the first output port 50a of the microcomputer 50 via the diode 4c. The diode 4 c is for preventing a reverse current from the threshold voltage setting circuit 25 toward the microcomputer 50. The source of the FET 210 is connected to the reference potential, the gate is connected to the connection point between the drain of the FET 208 and the resistor 206, and the drain is connected to the first output port 51a via the diode 4b.

  Further, in the threshold voltage setting circuit 25, the operational amplifier 220 is a logic operation circuit that connects the power supply voltage Vcc between the battery type determination resistor 7 of the battery pack 2 and the reference resistor 9 a provided in the charging device 1 to the non-inverting terminal. Divided voltage is input. On the other hand, the divided value of the resistors 211 and 212 connected in series between the power supply voltage Vcc and the reference potential is input to the inverting terminal as the reference voltage. For this reason, the operational amplifier 220 determines the magnitude of the battery type determination resistor 7 of the attached battery pack 2 with respect to the reference voltage. For example, when a battery pack 2 having a high rated voltage in which 10 cells are connected in series is mounted, the battery type discrimination resistor 7 has a relatively large resistance value of 1000 kΩ as an example. High voltage is input and a high signal is output. On the other hand, when a battery pack 2 ′ having a low rated voltage in which 5 cells are connected in series is mounted, the battery type discrimination resistor 7 has a resistance value smaller than that of the previous battery pack 2, for example, 500 kΩ. A voltage lower than the reference voltage is input to the non-inverting terminal, and a low signal is output.

  The output terminal of the operational amplifier 220 is connected to the gate of the FET 213. The FET 213 has a drain connected to the connection point between the anode of the Zener diode 201 and the anode of the diode 202, and a source connected to the reference potential. Therefore, when the signal output from the operational amplifier 220 is a high signal, the FET 213 is turned on, whereas when the signal is a low signal, the FET 213 is turned off. That is, in the present embodiment, when the battery pack 2 is a low rated voltage battery pack 2 ′ in which five battery cells 2 a are connected in series, the FET 213 is turned off. On the other hand, when the battery pack 2 is a high rated voltage battery pack 2 in which ten battery cells 2a are connected in series, the FET 213 is turned on. As a result, the path having the Zener diode 201 that defines the threshold of the low rated voltage is grounded from the node B via the FET 213, and thus does not contribute to the control of the FET 218.

  Next, the operation of the charging device 1 will be described with reference to FIGS.

  First, a case where a battery pack having a low rated voltage is connected to the charging device 1 will be described. When the battery pack 2 is mounted on the charging device 1 (step S1: YES), the battery type discrimination resistor 7 of the battery pack 2 is connected in series with the reference resistor 9a of the charging device 1, and the threshold voltage setting circuit 25 A voltage-divided value by the battery type discrimination resistor 7 and the reference resistor 9a at the voltage Vcc is input to the non-inverting input terminal of the operational amplifier 220. At this time, if the number a of the battery cells 2a constituting the battery pack 2 is 5 in series, the divided voltage value is smaller than the reference voltage, so the operational amplifier 220 outputs a low signal (step S2: low). ). The FET 213 is turned off by the low signal output from the operational amplifier 220 (step S3). At this time, voltages corresponding to the battery voltage are respectively applied to the Zener diodes 201 and 204, so that the FET 208 is turned on / off depending on the magnitude of the Zener voltage V1 of the Zener diode 201 and the battery voltage (Step S4). . This is because the Zener voltage V1 of the Zener diode 201 is smaller than the Zener voltage V4 of the Zener diode 204. Therefore, the battery voltage corresponding to the Zener diode 201 having a low breakdown voltage (Zener voltage) becomes the threshold value, and the FET 208 is controlled.

  With the above configuration, the presence or absence of the overdischarge state is determined using the breakdown voltage V1 of the Zener diode as a threshold voltage for determining the discharge limit of the battery pack 2. If the battery voltage is less than the breakdown voltage V1 of the Zener diode, that is, if the battery pack 2 is in a state below the discharge limit voltage (step S5: YES), the FET 208 is turned off (step S6), and the FET 210 is turned on. (Step S7). As a result, in the charge control signal transmission unit 4, the high signal output from the output port 51a is grounded via the diode 4c and the FET 210, and the input of the FET 4a is cut off, so that charging of the battery pack 2 is temporarily started. Even if it is a case, charge is stopped immediately (step S8). Since the breakdown voltage of the Zener diode 204 is higher than the breakdown voltage of the Zener diode 201, the path through the Zener diode 204 is not conducted at the voltage V1, and thus does not contribute to the control of the FET 208.

  On the other hand, when the battery voltage is equal to or higher than the zener voltage V1 (step S5: NO), the battery pack 2 is not in a state of the possibility of overdischarge, so the FET 208 is turned on (step S9) and the FET 210 is turned off. (Step S10). As a result, the threshold voltage setting circuit 25 is disconnected from the charging control signal transmission unit 4, so that the charging is continued when the output port 51 a outputs a high signal to charge the battery pack 2 (step) S11). When the battery voltage is higher than the breakdown voltage V4 of the Zener diode 204, not only the path of the Zener diode 201 but also the path of the Zener diode 204 is conducted, but the FET 208 is driven by any path. There is no change.

  On the other hand, when a battery pack with a high rated voltage is connected, that is, when the number a of the battery cells 2a constituting the battery pack 2 is 10 in series in step S2, the battery type identification resistor 7 and the reference resistance Since the divided voltage value of 9a is larger than the reference voltage, the operational amplifier 220 outputs a high signal (step S2: high). The FET 213 is turned on by the high signal output from the operational amplifier 220 (step S12). When the FET 213 is turned on, the path of the Zener diode 201 is grounded via the FET 213 as described above, and therefore the Zener diode 204 is dominant with respect to the on / off of the FET 208. Therefore, the threshold value of the battery voltage depends on the Zener voltage V4 of the Zener diode 204 (Step S13). After step S13, as in the case of the battery pack with the low rated voltage described above, whether to stop charging or continue charging is determined by comparing the battery voltage with the Zener voltage of the Zener diode 204 (Steps S5 to 11). .

  In this way, in the case of the battery pack 2 having a low rated voltage, the Zener voltage of the Zener diode 201 can be set as the threshold voltage, and in the case of the battery pack 2 having a high rated voltage, a Zener diode higher than the Zener diode 201 is used. A Zener voltage of 204 can be used as the threshold voltage. That is, according to the rated voltage of the battery pack 2 (the number of series cells), it is possible to selectively set the threshold voltage at the discharge limit for determining the presence or absence of the overdischarge state.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the threshold voltage is set using the threshold voltage setting circuit 25 including a plurality of Zener diodes having different breakdown voltages. However, the present invention is not limited to this circuit. For example, the following embodiment may be used. In the present embodiment, instead of the threshold voltage setting circuit 25 in the first embodiment, the microcomputer 50 of the charging apparatus 1 determines whether or not the battery pack 2 is in an overdischarged state as a determination unit. Therefore, the charging device 1 shown in FIG. 3 is the same as the charging device 1 shown in FIG. 1 except that the microcomputer 50 has the function of the threshold voltage setting circuit 25 and the threshold voltage setting circuit 25 as a hardware circuit is omitted. The configuration is the same.

  The operation of the charging apparatus 1 shown in FIG. 3 will be described with reference to FIG. The operation of the charging device 1 shown in FIG. 4 does not charge the battery pack 2 when it is determined that the battery voltage of the battery pack 2 has become equal to or lower than the discharge limit voltage.

  First, when the battery pack 2 is mounted on the charging device 1 (step S21: YES), the microcomputer 50 determines the number and rated voltage of the lithium ion batteries constituting the battery pack from the battery type identification resistor 7 of the battery pack 2. Based on the read and read rated voltage of the battery pack 2, the reference voltage setting circuit 25 sets a threshold voltage for a discharge limit for determining the overdischarge state of the battery pack 2 (step S22). For example, in the case of a battery pack having a rated voltage of 14V formed by connecting five lithium ion batteries in series, the battery pack having a rated voltage of 36V formed by connecting 10 lithium ion batteries in series with a threshold voltage of 9V In this case, the threshold voltage is set to 18V.

  Next, the battery voltage of the battery pack 2 detected by the battery voltage detection circuit 90 is compared with a threshold voltage to determine whether or not the battery pack 2 is in an overdischarged state (step S23). At this time, when a battery pack having a rated voltage of 14V is mounted, the battery voltage is compared with a threshold voltage of 9V. On the other hand, when a battery pack having a rated voltage of 36V is mounted, the battery voltage is compared with a threshold voltage of 18V. As described above, the threshold voltage set according to the rated voltage of the battery pack is compared with the actual battery voltage. If the battery voltage is equal to or lower than the threshold voltage (step S23: YES), the battery pack 2 is excessive. Charging is not performed assuming that the battery is in a discharged state (step S26). On the other hand, if the battery voltage is greater than the threshold voltage (step S23: NO), the microcomputer 50 starts charging the battery pack 2 (step S24).

  If the microcomputer 50 determines that the battery pack 2 is fully charged from the battery voltage detected by the battery voltage detection circuit 90 as a result of continuing charging of the battery pack 2 (step S25: YES), the battery pack 2 is charged. The process ends (step S26). On the other hand, if the battery pack 2 is not fully charged (step S25: NO), the microcomputer 50 continues charging until the battery pack 2 is fully charged. And if the battery pack 2 is removed from the charging device 1 (step S27: YES), the charging device 1 stands by in preparation for the next mounting of the battery pack 2. Although not clearly shown in the flow, even when the battery pack 2 is removed from the charging device before step S27, the charging device 1 resets the condition and is in a standby state for the next battery pack 2 to be mounted. It becomes.

  Thus, the threshold voltage, which is the discharge limit voltage for determining the overdischarge state of the battery pack 2, can be changed according to the rated voltage of the battery pack 2. Therefore, it is possible to determine the threshold value of the discharge limit voltage according to the rated voltage of the battery pack 2 using the single charging device 1, and to extend the life of the battery pack 2.

  Next, a modification example related to the charging operation of the charging device 1 shown in FIG. 3 will be described with reference to FIG. In this modified example, the charging device 1 precharges the battery pack 2 having a discharge limit voltage or less that may cause overdischarge of the battery pack 2, and determines whether or not to continue further charging based on the state of precharging. To do.

  First, when the battery pack 2 is mounted on the charging device 1 (step S31: YES), the microcomputer 50 of the charging device 1 determines the number of lithium ion batteries that constitute the battery pack from the battery type identification resistor 7 of the battery pack 2. Then, the rated voltage is read, and the threshold voltage of the battery pack 2 is set by the reference voltage setting circuit 25 from the read rated voltage of the battery pack 2 (step S32). For example, in the case of a battery pack having a rated voltage of 14V, the threshold voltage is set to 9V, and in the case of a battery pack having a rated voltage of 36V formed by connecting 10 lithium ion batteries in series, the threshold voltage is set to 18V.

  Next, the battery voltage of the battery pack 2 detected by the battery voltage detection circuit 90 is compared with a threshold voltage corresponding to the rated voltage (step S33). That is, the threshold voltage is compared with the actual battery voltage to determine whether or not the battery pack 2 is equal to or lower than the discharge limit voltage. If the battery voltage is equal to or lower than the threshold voltage (step S33: YES), since the battery pack 2 is in a state where there is a possibility of overdischarge, precharging is started instead of normal charging conditions (step S34). Note that the precharge is a charging method that is performed when the battery characteristics of the battery pack 2 are suspected to be deteriorated because the battery voltage of the battery pack 2 is equal to or lower than the discharge limit voltage, and is performed when the battery pack 2 is not in an overdischarged state. Compared to normal charging, the charging is performed under “gentle” charging conditions such as low current and low voltage.

  When the precharge of the battery pack 2 is started, the microcomputer 50 continuously or intermittently detects the battery voltage of the battery pack 2 (step S35), and when the detected battery voltage exceeds the threshold voltage (step S36). : YES), it is determined that the battery pack 2 is normal, the charging current I1 larger than the charging current I2 is switched to continue charging (step S37), and the process proceeds to step S42.

  On the other hand, when the detected battery voltage does not exceed the threshold voltage (step S36: NO), the process proceeds to step S38, and it is determined whether or not a predetermined time has elapsed since the start of precharge. If the predetermined time has already passed (step S38: YES), it is estimated that some abnormality has occurred in the battery cell, and charging is stopped in step S43. If the predetermined time has not elapsed since the start of the precharge (step S38: NO), the process returns to step S36, the flow is repeated until the predetermined time elapses, and the battery voltage of the battery pack 2 is continuously monitored.

  On the other hand, when the battery voltage detected in step S33 exceeds the threshold voltage, it is determined that the battery pack 2 is not in an overdischarged state (step S33: NO), and then the protection IC 2b of the battery pack 2 is obtained. Whether or not a signal is generated is determined (step S40). If there is no signal from the protection IC 2b (step S40: NO), charging is started with the charging current I1 under normal conditions (step S41). When charging is continued and it is determined that the battery pack 2 is fully charged (step S42: YES), the charging is terminated (step S43). Thereafter, when the battery pack 2 is removed from the charging device 1 (step S44: YES), the charging device 1 stands by in preparation for future mounting of the battery pack 2. If the battery pack 2 is removed before the end of charging, the charging device 1 resets the conditions and waits for the next battery pack 2 to be mounted, as in the previous embodiment.

  If a signal is generated from the protection IC 2b in step S40 (step S40: YES), the battery is already fully charged or the protection IC 2b prohibits charging for some reason. In step S43, the battery pack 2 is not charged and charging is terminated (step S43).

  The microcomputer 50 can appropriately determine the overdischarge state of the battery pack 2 by appropriately changing the threshold voltage for determining the overdischarge state of the battery pack 2 according to the rated voltage of the battery pack 2. Further, when it is determined that the battery pack 2 is in an overdischarged state, precharge is performed for a predetermined period, and the normality or abnormality of the battery pack 2 is confirmed from the state of the voltage increase of the battery pack 2 at that time. Whether or not charging is continued can be determined.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the threshold voltage for determining the overdischarge state by the threshold voltage setting circuit 25 can be changed between a battery pack having a large number of cells connected in series and a battery pack having a small number of cells connected in series. The precharge and the charge are attempted with respect to the battery pack whose voltage is lower than the limit voltage and the signal is output from the battery cell 2a. The charging device of the present embodiment includes an abnormal signal processing circuit 250 in addition to the components shown in charging device 1 shown in FIG. In the following description, only parts different from the configuration of the charging apparatus shown in FIG. 1 will be described.

  As shown in FIG. 6, the charging device 1 further includes an abnormal signal processing circuit 220. The abnormal signal processing circuit 220 includes resistors 214, 125, and 127 and FETs 216 and 218, and is inserted between the threshold voltage setting circuit 25 and the first output port 51a of the microcomputer 50, and includes a protection IC 2b and a threshold voltage. Based on the signal from the setting circuit 25, a signal for stopping charging is input to the A / D input port 52 of the microcomputer 50, and the signal output from the microcomputer 50 to the charging signal transmission unit 4 is cut off.

  In the abnormal signal processing circuit 220, a resistor 214 and an FET 216 are connected in series in order from the power supply voltage Vcc side between the power supply voltage Vcc and the reference potential. The FET 216 has a drain connected to the resistor 214 and is connected to the A / D input port 52 of the microcomputer 50. The FET 216 has a source connected to the reference potential and a gate connected to the protection IC 2 b of the battery pack 2. The resistor 215 is connected between the gate and the source of the FET 216. The FET 218 has a drain connected to the output line of the first output port 51a of the microcomputer 50 via the diode 4c, a source connected to the reference potential, and a gate connected to a node C that is a connection point between the resistor 214 and the drain of the FET 216. It is connected. A resistor 217 is connected between the source and gate of the FET 218.

  Next, the operation of the charging apparatus 1 shown in FIG. 6 will be described with reference to FIG.

  First, when the number of battery cells 2a of the battery pack 2 connected in series is small, that is, when the battery pack 2 is mounted on the charging device 1 (step S51: YES), the battery type determination resistor 7 of the battery pack 2 is connected to the charging device. In the threshold voltage setting circuit 25, the divided value of the power source voltage Vcc by the battery type discrimination resistor 7 and the resistor 9 is input to the non-inverting input terminal of the operational amplifier 220. At this time, if the number of battery cells 2a constituting the battery pack 2 is 5 in series connection, the divided voltage value is smaller than the reference voltage, so the operational amplifier 220 outputs a low signal (step S52: low). ). The FET 213 is turned off by the low signal output from the operational amplifier 220 (step S53). At this time, voltages corresponding to the battery voltage are respectively applied to the Zener diodes 201 and 204, so that the FET 208 is turned on / off depending on the magnitude of the Zener voltage V1 of the Zener diode 201 and the battery voltage (Step S54). . That is, the Zener voltage V1 of the Zener diode 201 is a threshold voltage for determining whether or not the battery pack 2 is in an overdischarged state.

  When the battery voltage is equal to or lower than the threshold voltage V1, it is determined that the battery pack 2 is equal to or lower than the discharge limit voltage that may cause overdischarge (step S55: YES), the FET 208 is turned off (step S56), and the FET 210 Is turned on (step S57). At this time, a signal (low signal) warning the overdischarge is also output from the protection IC 2b (step S58: low), and the FET 216 is turned off (step S59). Accordingly, the FET 218 is turned on by the Vcc applied to the abnormal signal processing circuit 250 in response to the FET 216 being turned off. However, as described above, the FET 210 of the threshold voltage setting circuit 25 is turned on. No signal is applied and FET 218 remains off. For this reason, the A / D input port 52 of the microcomputer 50 also becomes a low signal (step S60). On the other hand, the microcomputer 50 outputs a high signal from the output port 51a in order to precharge the battery pack 2 based on the battery voltage from the battery pack 2. Therefore, the high signal is transmitted to the charge control signal transmission unit 4 without being lowered to the reference potential by the FET 218, and the battery pack 2 can be precharged (step S61).

  Even when no signal (low signal) is output from the protection IC 2b of the battery pack 2 (step S58: high), the FET 216 is turned on (step S62) and the FET 218 is turned off (step S63). . Therefore, as in the previous case, since the microcomputer 50 precharges the battery pack 2, the high signal output from the output port 51 a is transmitted to the charge control signal transmission unit 4 without being lowered to the reference potential by the FET 218. The At this time, the microcomputer 50 precharges the battery pack 2 based on the battery voltage from the battery pack 2 (step S61).

  When the battery voltage exceeds the threshold voltage V1 in step S55, it is determined that the battery pack 2 is not in an overdischarged state (step S55: NO), the FET 208 is turned on (step S62), and the FET 210 is turned off. (Step S63). That is, the threshold voltage setting circuit 25 is electrically disconnected from the charging device 1. At this time, if a signal (low signal) is output from the protection IC 2b (step S64: low), the FET 216 is turned off (step S65), and the FET 216 is turned off to the A / D port 52 of the microcomputer 50. Is inputted with a high signal for stopping charging, and at the same time, the FET 218 is turned on (step S66). Therefore, the microcomputer 50 stops the output from the output port 51a based on the signal prohibiting charging, and even if the output port 51a of the microcomputer 50 continues to output the high signal, the FET 218 Therefore, the charging of the battery pack 2 is forcibly terminated (step S67).

  If no signal (low signal) is output from the protection IC 2b in step S66 (step S66: high), normal charging is possible, and the FET 216 is turned on (step S68). The D port 52 becomes a low signal and the FET 218 is turned off (step S69). Therefore, charging of the battery pack 2 is continued (step S70).

  In this way, when the number of battery cells 2a connected in series in the battery pack 2 is small, the Zener voltage of the Zener diode 201 can be set as a threshold voltage for determining whether or not there is an overdischarge state. When the number of battery cells 2a connected in series is large, a Zener voltage higher than the Zener diode 201 of the Zener diode 204 can be used as a threshold voltage for determining whether or not an overdischarge state exists. That is, it becomes possible to selectively set the threshold voltage for determining the presence or absence of the overdischarge state according to the number of series cells of the battery pack 2.

  In step 52, if the number a of the series connection of the battery cells 2a constituting the battery pack 2 is 10 cells corresponding to the high rated voltage, the divided voltage value is larger than the reference voltage. Is output (step S52: high). The FET 213 is turned on by the high signal output from the operational amplifier 220 (step S71). When the FET 213 is turned on, the Zener diode 204 becomes dominant for turning the FET 208 on and off, and thus depends on the Zener voltage V4 of the Zener diode 204 (Step S72). That is, the Zener voltage V4 of the Zener diode 204 is a threshold voltage that determines whether or not the battery pack 2 is in an overdischarged state. In the processes after step S74, it is determined whether precharge, charge stop, or charge continuation is the same as the battery pack 2 'having the low rated voltage described above (steps S55 to S70).

  As described above, in the normal charging device, charging is stopped when the battery pack 2 is below the discharge limit voltage and a signal warning overdischarge is generated from the protection IC 2b of the battery cell 2a. In the embodiment, even in such a case, the microcomputer 50 can precharge the battery pack 2 and continue.

  In addition, since the determination of the overdischarge state of the battery pack 2 is performed by the threshold voltage setting circuit 25 and the abnormal signal processing circuit 220 without using the microcomputer 50, even if a malfunction occurs in the microcomputer 50, The threshold voltage for determining the overdischarge state is controlled according to the number of series battery cells in the battery pack 2.

(Fourth embodiment)
Next, the charging device 1 which is the 4th Embodiment of this invention is demonstrated with reference to FIG.8 and FIG.9. The charging device 1 shown in FIG. 8 has the same basic configuration as the charging device 1 compared to the charging device 1 shown in FIG. In the threshold voltage setting circuit 25 shown in FIG. 6, the operational amplifier 220 of 1 is used to classify the resistance value of the battery type discrimination resistor 7 of the battery pack 2 into two large and small, and the threshold voltage for discriminating the overdischarge state is set. The two can be selected according to the number of Zener diodes. In the threshold voltage setting circuit 25A of the present embodiment shown in FIG. 8, the two operational amplifiers 220 and 224 are used to classify the resistance value of the battery type discrimination resistor 7 of the battery pack 2 into three, and the overdischarge state is determined. In order to set three threshold voltages to be discriminated, three Zener diodes are provided so that the threshold voltage can be selected from the three.

  The threshold voltage setting circuit 25 includes operational amplifiers 220 and 224, resistors 200, 203, 206, 207, 209, 211, 212, 221, 222, and 224, FETs 208, 210, 213, and 223, Zener diodes 201, 204, and 225, and a diode. 202, 205, and 226. The Zener diodes 201, 204, and 225 have the highest Zener voltage for the Zener diode 204 and the smallest Zener diode 225. For the operational amplifiers 220 and 224, the reference voltage input to the inverting input terminal is set so that the operational amplifier 220 is larger than that of the operational amplifier 224.

  Next, the operation of the charging apparatus 1 shown in FIG. 8 will be described with reference to FIG.

  First, when the battery pack 2 having a low rated voltage in which the number of battery cells 2a connected in series is about 5 cells is mounted on the charging device 1 (step S81: YES), the battery type determination resistor 7 of the battery pack 2 is connected to the charging device. In the threshold voltage setting circuit 25, the divided value of the power source voltage Vcc by the battery type discrimination resistor 7 and the resistor 9 is input to the non-inverting input terminals of the operational amplifiers 224 and 220, respectively. At this time, when the number a of the battery cells 2a constituting the battery pack 2 is 5 in series, the operational amplifier 220 and the operational amplifier 224 are both low due to the voltage divided from the identification resistor 7 and the reference resistor 9a. A signal is output (step S82: low). In this state, the FET 223 is off and the FET 213 is also off (step S83). At this time, voltages corresponding to the battery voltage are respectively applied to the Zener diodes 201, 204, and 225. Therefore, the FET 208 has a magnitude that is smaller than the Zener voltage of the Zener diode 225 having the smallest breakdown voltage of the Zener diode and the battery voltage. It is turned on / off (step S84). That is, the Zener voltage of the Zener diode 225 becomes a threshold voltage for determining whether or not the battery pack 2 is in an overdischarged state.

  On the other hand, for example, when the battery pack 2 has a moderate rated voltage and the number a of the battery cells 2a connected in series is 7, the operational amplifier in step S82 is divided by the voltage divided based on the value of the identification resistor 7. 224 outputs a high signal (step S82: high), but the output from the other operational amplifier 220 becomes a low signal. (Step S85: Low) In this case, the FET 223 is turned on, but the FET 213 remains off (Step S86). At this time, the FET 208 is turned on / off depending on the magnitude of the Zener voltage of the Zener diode 201 having an intermediate breakdown voltage and the battery voltage (Step S87). That is, the Zener voltage of the Zener diode 201 becomes a threshold voltage for determining whether or not the battery pack 2 mounted is in an overdischarged state.

  Further, when the connected battery pack 2 is a battery pack of high rated voltage specification, for example, the number a of the battery cells 2a connected in series is 10 cells, the operational amplifier 224 is determined in step S82 based on the value of the identification resistor 7. Outputs a high signal (step S82: high), and the output from the other operational amplifier 220 is also a high signal (step S85: high), so that both FET 223 and FET 213 are turned on (step S88). At this time, the FET 208 is turned on / off depending on the magnitude of the Zener voltage of the Zener diode 204 having the highest breakdown voltage and the battery voltage (Step S89). That is, the Zener voltage of the Zener diode 204 is a threshold voltage that determines whether or not the battery pack 2 that has been mounted is in an overdischarged state.

  After selecting an appropriate one from the three threshold voltages using three Zener diodes according to the number of battery cells 2a connected in series in the battery pack 2 as described above, FIG. Proceeding to step S55, precharging, stopping charging, or normal charging is performed in accordance with the overdischarge state of the battery pack 2 and a signal from the protection IC 2b.

  Therefore, the threshold voltage of the discharge limit voltage can be selected according to the number of battery cells connected in series in the battery pack.

  In addition, the said embodiment only illustrates one form of this invention, The number of series cells of the battery cell which comprises a battery pack can be provided suitably.

  In the above embodiment, the number of Zener diodes included in the threshold voltage setting circuit is exemplified as two and three. However, the present invention is not limited to these examples, and a plurality of Zener diodes can be provided. Depending on the number of Zener diodes, a plurality of threshold voltages for determining overdischarge can be provided. Furthermore, in the above-described embodiment, the embodiment in which precharge is performed and the embodiment in which no precharge is performed is illustrated for all threshold values. Alternatively, it may be configured not to be performed.

DESCRIPTION OF SYMBOLS 1 Charging apparatus 2 Battery pack 7, 9 Identification means 25 Discrimination means 50 Control means 90 Detection means

Claims (9)

Charging means capable of selectively charging battery packs having different rated voltages;
Identifying means for identifying the rated voltage of the battery pack connected to the charging means;
Detecting means for detecting a battery voltage of a battery pack connected to the charging means;
Based on a signal from the detection means, a determination means for determining whether or not a battery pack connected to the charging means is below a discharge limit voltage;
Have
The determination means defines a plurality of threshold voltages having different values, and selects one of the plurality of threshold voltages according to the rated voltage of the battery pack identified by the identification means. A charging device characterized by performing.   The charging device according to claim 1, wherein the determination unit has two threshold voltages.   The charging device according to claim 1, wherein the determination unit has at least three threshold voltages.   4. The charging device according to claim 1, wherein the determination unit includes a Zener diode corresponding to each of the threshold voltages. 5. The charging device has a logic operation circuit,
4. The charging device according to claim 1, wherein the determination unit compares a threshold voltage with the battery voltage by the logic operation circuit. 5. And further has a control means for controlling the charging means,
The control unit does not charge the battery pack by the charging unit when the determining unit determines that the battery pack is equal to or lower than the discharge limit voltage. A charging device according to claim 1. And further has a control means for controlling the charging means,
The control means precharges the battery pack by the charging means when the determining means determines that the battery pack is equal to or lower than the discharge limit voltage. The charging device according to one.   8. The charging according to claim 1, wherein the determination unit is configured to detect a signal generated when the battery pack is fully charged or overdischarged to determine a state of the battery pack. apparatus.   The charging device according to any one of claims 1 to 8, wherein the battery pack includes a battery cell made of a lithium ion battery.

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