JP2007068264A - Charger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a versatile charger for reducing a power consumption when the charger waits to charge and enabling a constant current/constant voltage charging control and a constant current charging control for reducing an inrush current transiently flowing when the charger starts to charge. <P>SOLUTION: An output voltage controlling means 80 reduces the inrush current Id flowing into a switch means 121 when the switch means 121 is controlled to be switched from an ON state to an OFF state by setting an output voltage of a charging power supply means 300 to a predetermined voltage corresponding to a battery voltage of a battery pack 2 detected by a battery voltage detecting means 8 when a switch means 121 is turned off, sets the output voltage of the charging power supply means 300 to a predetermined value corresponding to a charging voltage dependent on a type of the battery pack 2 when the switch means 121 is turned on, and starts charging. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charging device for a secondary battery, and in particular, a lithium battery that requires constant current / constant voltage charging control, and a nickel metal hydride battery, a nickel cadmium battery (hereinafter referred to as a Nicad battery) that require constant current charging control. The present invention relates to a general-purpose charging device for charging various battery packs that require different charging control methods and different battery voltages.

  With the development of portable devices such as cordless electric tools, secondary batteries with high capacity such as nickel metal hydride batteries and nickel-cadmium batteries are being used as power sources for portable devices. As another example of a secondary battery having a higher capacity, a lithium battery that can extract a larger amount of electricity than a nickel metal hydride battery or a nickel-cadmium battery is being used in portable devices. Note that the lithium battery in this specification refers to a vanadium / lithium battery, a manganese / lithium battery, etc., and a battery using a lithium / aluminum alloy for the negative electrode and an organic electrolyte. In general, a lithium ion battery is a battery in which lithium cobaltate is used for a positive electrode, graphite is used for a negative electrode, an organic electrolytic solution is used as an electrolytic solution, and lithium ions are present in a negative electrode during charging. Since lithium species are deeply involved in the battery reaction, for the sake of convenience, in the present application, the lithium battery including the lithium ion battery is simply referred to as a lithium battery.

  The nominal cell voltage of lithium batteries is about 2 to 3 times higher than that of nickel-metal hydride batteries and nickel-cadmium batteries, which are widely used in practice. Its energy density is about 3 times that of nickel-cadmium batteries, and it is compact and lightweight. It has the characteristic of being. Furthermore, it has good discharge efficiency, can be discharged even in a relatively low temperature environment, and can obtain a stable voltage over a wide temperature range.

  These secondary batteries naturally have a larger number of battery cells (number of unit cells) accommodated in the battery pack (battery set) as the required voltage increases as in a cordless electric tool or the like. For example, since the nominal voltage of a nickel-cadmium battery or a nickel metal hydride battery cell is 1.2V, 12 battery tools are used in a power tool with a battery voltage of 14.4V, and 20 battery cells are stored in a battery pack when the battery voltage is 24V. In addition, when a lithium battery is used, especially in a lithium ion battery cell, the nominal voltage is as high as 3.6 V. Therefore, when the battery voltage is 14.4 V, four battery cells are stored in the battery pack. There is a need.

  Since various battery packs with different battery voltages are used corresponding to various portable devices, general-purpose charging devices that charge various battery packs with different numbers of battery cells with a single charging device have become widespread. ing. This general-purpose charging device is disclosed, for example, in Patent Document 1 below. Further, in the charging method of the battery pack of the lithium battery including the lithium ion battery, the constant current / constant voltage control as shown in FIG. 7 is required, while in the charging method of the nickel metal hydride battery and the nickel cadmium battery as shown in FIG. Since constant current control is required, general-purpose charging devices that can charge a plurality of types of battery packs that require different battery voltages and different charging controls with a single charging device are also becoming widespread.

  In the latter general-purpose charging device, when charging a battery pack of nickel metal hydride battery and nickel-cadmium battery, constant current control is performed, so the voltage value corresponding to the battery pack with the largest number of battery cells that can be charged by the charging device is set. Must be set as output voltage. For this reason, as disclosed in Patent Document 1, in a charging device in which a relay switch for controlling on / off of a charging current path is inserted between a charging power source and a battery pack to be charged, a low voltage with a small number of battery cells is provided. When charging the battery pack, if the relay switch is closed to charge, the high output voltage corresponding to the high voltage battery pack with many battery cells is excessively applied to the battery pack with few battery cells, and the relay switch is closed. At that moment, a transient inrush current flows. As a result, the relay switch existing in the charging current path is seriously damaged. Also, when the battery pack to be charged is not installed in the charging device or when the battery pack is determined to be fully charged and charging is terminated, the relay switch is turned off and the charging current supply is cut off. Since the control is performed so that the highest output voltage required for the battery pack having the largest number of battery cells that can be charged by the charging device can be supplied, the power consumption increases even when the relay switch is turned off.

  In order to solve the problem of the inrush current from the charging power source to the battery pack to be charged, according to the technique disclosed in Patent Document 1, an output voltage setting unit capable of setting a plurality of output voltages is provided, and at the time of charging When the relay switch is turned on, the output voltage of the charging power supply is set to a first output voltage higher than the battery voltage required for the battery pack being charged, and when the relay switch is turned off, the output voltage of the charging power supply Has been proposed that sets the second output voltage to be smaller than the first output voltage.

JP 2004-187366 A

  However, as in the technique disclosed in Patent Document 1, it is possible to charge a nickel metal hydride battery or a nickel-cadmium battery with constant current control only by providing output voltages corresponding to a plurality of battery cells that can be simply charged. Insufficient to charge a lithium battery. In order to charge a lithium battery without deterioration and to obtain a sufficient charge / discharge capacity, high-precision constant voltage control is required. For example, in the case of a lithium ion battery, there is a characteristic that battery deterioration and sufficient capacity cannot be obtained unless charging is performed with an accuracy of about 4.2 V / cell ± 50 mV. That is, particularly in charging a lithium battery, a general-purpose charging device capable of outputting a controlled charging voltage is required.

  In addition, as in the technique disclosed in Patent Document 1, when the battery pack is waited for mounting and charging is not performed, it is only necessary to set the second output voltage lower than the first output voltage during charging. It is insufficient from the viewpoint of reducing power consumption.

  Furthermore, if a power supply for a control system such as a microcomputer or an operational amplifier is provided as the second power supply circuit separately from the charging power supply circuit for simply supplying charging power to the battery pack to be charged, the relay switch can be deleted. It is possible to solve the problem of inrush current. However, in such a charging device, for example, when the battery pack to be charged has a mounting structure in which the positive and negative electrodes (+-) of the battery pack can be inserted in reverse, when the positive and negative electrodes are mounted in reverse. In addition, the smoothing capacitor on the output voltage side of the charging power supply circuit is reversely charged and the capacitor is damaged. Therefore, the relay switch cannot be deleted easily.

  Accordingly, an object of the present invention is to reduce power consumption during charging standby, to suppress a transient inrush current to the charged battery pack at the start of charging, and to provide different battery voltages and An object of the present invention is to provide a general-purpose charging device capable of charging a battery pack having different charge control methods.

  Another object of the present invention is to provide a charging device capable of charging a battery pack such as a nickel cadmium battery and a nickel metal hydride battery by a constant current control method, and at the same time, a battery pack such as a lithium battery can be charged with a constant current and a constant current. An object of the present invention is to provide a general-purpose charging device that can be charged by a voltage control method.

  Among the inventions disclosed in accordance with the present invention in order to solve the above problems, the characteristics of typical ones will be described as follows.

  According to one aspect of the present invention, charging is possible in which a plurality of types of battery packs having different battery voltages and charging methods of constant current / constant voltage control or constant current control can be charged by a single charging device. A charging power source means for supplying charging power to a battery pack to be charged, and a charging current path between the charging power source means and the battery pack, and the charging current path is turned on / off Switch means for controlling, output voltage detecting means for detecting the output voltage of the charging power supply means, battery voltage detecting means for detecting the battery voltage of the battery pack, and the battery pack electrically connected to the charging power supply means, A charging current control means for controlling the charging current flowing through the battery pack, and an output for controlling the output voltage of the charging power supply means to a predetermined voltage corresponding to the battery voltage of the battery pack. An output voltage control unit including a voltage setting unit; and a microcomputer that receives a detection signal including output signals of the output voltage detection unit and the battery voltage detection unit and controls the switch unit and the output voltage control unit. The output voltage control means sets the output voltage of the charging power supply means to a predetermined voltage corresponding to the battery voltage of the battery pack detected by the battery voltage detection means when the switch means is in an off state, The output voltage control means performs charging by setting the output voltage of the charging power supply means to a predetermined voltage higher than the battery voltage to be charged in the battery pack when the switch means is in an ON state.

  According to another feature of the present invention, the driving power source for driving the microcomputer, the output voltage setting means, the switch means, and the battery voltage detecting means is a separate power source independent of the charging power source means. When the battery pack to be charged is not mounted, the output of the charging power supply means is stopped.

  According to still another aspect of the present invention, there is provided battery pack detection means for detecting a plurality of types of the battery packs having different battery voltages and being charged by constant current / constant voltage control or constant current control. Built in the battery pack, the microcomputer determines the type of the battery pack based on a detection signal detected based on the battery pack detection means.

  According to still another aspect of the present invention, the switch means includes a relay switch, and a switch control circuit including a control coil of the relay switch is on / off controlled by the microcomputer.

  According to still another aspect of the present invention, the battery pack to be charged is a lithium battery that is charged by constant current / constant voltage control, and a nickel metal hydride battery and a nickel-cadmium battery that are charged by constant current control.

  According to the present invention, the output voltage control means has a predetermined output voltage corresponding to the battery voltage of the battery pack detected by the battery voltage detection means when the switch means is in an OFF state. And the output voltage control means sets the output voltage of the charging power supply means to a predetermined voltage higher than the battery voltage to be charged in the battery pack when the switch means is in an ON state. Since charging is performed, it is possible to reduce power consumption during charging standby, suppress transient inrush current to the battery pack to be charged at the start of charging, and use different battery voltages and different charge control methods. A general-purpose charging device capable of charging a battery pack having the battery pack can be provided.

  According to the present invention, since the charging current control means and the output voltage control means are provided, a charging device capable of charging a battery pack such as a nickel cadmium battery and a nickel hydride battery by a constant current control method is provided. A general-purpose charging device capable of charging a battery pack such as a lithium battery by a constant current / constant voltage control method can be provided.

  The above and other objects, and the above and other features and advantages of the present invention will become more apparent from the following description of the present specification and the accompanying drawings.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 6. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted.

  FIG. 1 shows a circuit diagram of a charging apparatus according to an embodiment of the present invention. In FIG. 1, a battery pack 2 to be charged by a charging device 200 includes a single or a plurality of rechargeable, for example, lithium battery cells 2a and a battery cell for detecting the battery temperature in the battery pack 2. A temperature sensing element 2b functioning as a temperature detection sensor such as a thermistor disposed in contact with or in close proximity to 2a, and the battery pack 2 includes a battery type such as a nickel metal hydride battery, a nickel-cadmium battery, and a lithium battery, and a battery cell. There is a battery type discriminating means 2c for discriminating the number of cells 2a. In the present embodiment, the battery type discriminating means 2c is composed of the resistor 2c having a resistance value that differs depending on the battery type. However, the battery type may be displayed by a type code and the code may be read out. For example, the battery pack 2 includes three lithium ion batteries (cells) in which the battery cell 2a has a nominal voltage of 3.6V connected in series, and has a total voltage of 10.8V.

  A charging power supply circuit (first power supply circuit) 300 for supplying charging power to the battery pack 2 includes a first rectifying / smoothing circuit 10, a switching power supply circuit 20, and a second rectifying / smoothing circuit 30. The

  The first rectifying / smoothing circuit 10 includes a full-wave rectifying circuit 11 and a smoothing capacitor 12, and full-wave rectifies the AC power source 1 such as a commercial AC power source. The switching power supply circuit 20 includes a high-frequency transformer 21, a MOSFET (switching element) 22 connected in series to a primary coil of the transformer 21, and PWM control for modulating the pulse width of a drive pulse signal applied to the gate electrode of the MOSFET 22. IC (switching power supply IC) 23. The PWM control IC 23 controls the start and stop of the charging operation of the MOSFET 22 based on the control input signals input from the charge control signal transmission means 4 and the charge feedback signal transmission means 5 made of a photocoupler, and is applied to the gate electrode of the MOSFET 22. By changing the drive pulse width to be supplied, the ON time of the MOSFET 22 is controlled, and the output voltage of the rectifying and smoothing circuit 30 and the charging current of the battery pack 2 are adjusted. The second rectifying / smoothing circuit 30 includes diodes 31 and 32 connected to the secondary coil side of the transformer 21, a choke coil 33, a smoothing capacitor 34, and a discharging resistor 35.

  Between the battery pack 2 and the output side (output terminal 30a) of the charging power supply means 300 including the first rectifying / smoothing circuit 10, the switching power supply circuit 20, and the second rectifying / smoothing circuit 30, there is a charging current path. Switch means 121 for controlling opening and closing (on / off) is electrically connected. The switch means 121 is composed of, for example, a relay, and the drive coil 121a of the relay 121 is driven by a relay control circuit 7 including a switching transistor 7a and bias resistors 7b and 7c. The relay control circuit 7 is on / off controlled by a control signal output from the microcomputer 50.

  On the other hand, a charging current control means 60 and a constant voltage control means 80 are electrically connected to the charging power supply means 300 composed of the first rectifying and smoothing circuit 10, the switching power supply circuit 20, and the second rectifying and smoothing circuit 30. Is done.

  The charging current control means 60 includes operational amplifiers 61a and 61b, input resistors 62 and 64 of the operational amplifiers 61a and 61b, feedback resistors 63 and 65 of the operational amplifiers 61a and 61b, a resistance 66 that constitutes the charging current setting means, and An operational amplifier circuit including a resistor 67 and an output circuit including a diode 69 and a diode current limiting resistor 68 is included. An output voltage Vcc of a constant voltage power supply (second power supply circuit) 100 that supplies power for driving a control circuit and a microcomputer, which will be described later, is supplied to the voltage dividing resistors 66 and 67 that provide the set potential. The input side of the charging current control means 60 is connected to the current detection means 3 comprising a resistor for detecting the charging current of the battery pack 2. Further, as described above, the output side controls the PWM control IC 23 via the charging feedback signal transmission means 5 comprising a photocoupler. Based on such a configuration, the charging current control means 60 controls the charging current supplied to the battery pack 2 to a constant value.

  The constant voltage control means 80 includes an operational amplifier 81, an inverting input terminal (−) side input resistor 82, a feedback resistor 84, a non-inverting input terminal (+) side input resistor 83, a diode 86, and a diode current limiter. And an output circuit composed of a resistor 85 for use. The input side of the constant voltage control means 80 is connected to the output voltage detection means 40 of the charging power source composed of the resistor 41 and the resistor 42, and the detection voltage for feedback of the output voltage of the charging power supply circuit 300 described above is inputted. The output side controls the PWM control IC 23 via the charging feedback signal transmission means 5 made of a photocoupler, similarly to the output side of the charging current control means 60. Therefore, the PWM control IC 23 is controlled by the output signal (feedback signal) of the charging current control means 60 or the constant voltage control means 80.

  Further, the output voltage setting means 6 is connected to the non-inverting input terminal of the operational amplifier 81 through a resistor 83. The output voltage setting means 6 is composed of a potentiometer circuit composed of fixed resistors 6a to 6e and variable resistors 6f to 6j. The set voltage supplied from the output voltage setting means 6 to the non-inverting input (+) of the operational amplifier 81 is set to various voltage values by the digital control signals of the four ports 53f to 53i in the output port 53 of the microcomputer 50. The output voltage of the second rectifying / smoothing circuit 30 (voltage of the output terminal 30a) is controlled to a predetermined output voltage value by the feedback action of the constant voltage control means 80 according to the set voltage value. For example, when the output port 53f of the microcomputer 50 connected to the potentiometers 6f, 6g, 6h and 6i is set to low output and the other output ports 53g to 53i are set to high impedance output, output to the non-inverting input terminal (+) of the operational amplifier 81 A predetermined set voltage is applied from the voltage setting means 6, and the output voltage of the second rectifying / smoothing circuit 30 (voltage of the output terminal 30a) is a constant current / constant voltage charge control for the battery pack 2 of the lithium ion battery of one cell. Is set to 4.2 V, which is necessary to On the other hand, when the output port 53g is a low output and the output ports 53f and 53h to 53i are a high impedance output, the output voltage of the second rectifying / smoothing circuit 30 is a constant current / It is set to 8.4 V necessary for constant voltage charge control. Similarly, when the output port 53h is set to low output and the output ports 53f, 53g, and 53i are set to high impedance output, 12.6V for charging the battery pack 2 of the 3-cell lithium ion battery at a constant current and a constant voltage is used. When the output port 53i is set to low output and the output ports 53f to 53h are set to high impedance output, 16.8V is output for charging the battery pack 2 of the 4-cell lithium ion battery at a constant current and a constant voltage, Furthermore, when all the output ports 53f-53i are set as a high impedance output, 25V for constant-current charge of the battery pack 2 of a nickel metal hydride battery or a nickel-cadmium battery is output. FIG. 3 is a set voltage example showing a relationship between various set voltages according to the type of battery and the number of cells of the battery and the signal levels of the output ports 53f to 53j of the microcomputer 50 described above. In FIG. 3, the signal level of the above-described output port is displayed as “L” in the case of a low output, and “H” in the case of a high impedance output. Since the output voltage setting means 6 can accurately adjust the set voltage by readjusting the variable resistors 6f to 6j, the output voltage setting means 6 has high accuracy according to the number of cells of the lithium ion battery built in the battery pack 2. Charging can be performed with the output voltage. Therefore, the constant voltage control means 80 and the output voltage setting means 6 constitute an output voltage control means for setting the output voltage of the charging power supply means 300.

  The operations of the charging power source means 300, the charging current control means 60, the constant voltage control means 80, the output voltage setting means 6, the battery temperature detection means 70, etc. are controlled by a microcomputer (control means) 50. Although not shown, the microcomputer 50 is a read only memory (ROM) that stores a control program of the CPU 51, data related to the battery type of the battery pack, and the like, in addition to a CPU (central processing unit) 51 that executes a control program. A random access memory (RAM) used as a work area of the CPU 51, a temporary data storage area, and the like, and a timer. Further, the microcomputer 50 converts the analog input signal detected by the battery type discrimination resistor 2c, the battery voltage detection means 8, the output voltage detection means 9 and the battery temperature detection means 70 into a digital output signal. The converter 52, the output port 53 (including ports 53f to 53i) for outputting control signals to the output voltage setting means 6 and the relay control circuit 7, and the charge control signal transmission means 4 are controlled to start or stop charging. An output port 54 for outputting a control signal and a reset input port 55 for inputting a reset signal when the power is turned on.

  The temperature sensing element 2b of the battery pack 2 is connected to a battery temperature detecting means 70 composed of series resistors 71 and 72 to which the drive power supply voltage Vcc is fed, converts the temperature change of the resistance value into a voltage, and Input to the D converter 52.

  Since the battery type discrimination resistor 2c of the battery pack 2 has a resistance value corresponding to the number of cells and the battery type of the battery pack 2 as described above, it forms a voltage dividing circuit together with the resistor 120 having one end connected to the drive power source Vcc. Then, the divided voltage is input to the A / D converter 52 of the microcomputer 50, and the microcomputer 50 determines the type of battery of the battery pack 2.

  The battery voltage of the battery pack 2 is divided as a detection voltage by the battery voltage detection means 8 including the voltage dividing resistors 8 a and 8 b and is input to the A / D converter 52 of the microcomputer 50.

  The output voltage detection means 9 comprises two voltage dividing resistors 9a and 9b connected in series, and inputs the detection voltage divided by both resistors to the A / D converter 52 of the microcomputer 50.

  A control signal for starting or stopping charging of the battery pack 2 is supplied from the output port 54 to the control input of the PWM control IC 23 via the charge control signal transmission means 4 in accordance with the control program of the microcomputer 50. If a charge start control signal is received from the charge control signal transmission means 4, the PWM control IC 23 causes the MOSFET 22 to start a switching operation. Conversely, if a charge stop control signal is received, the MOSFET 22 stops the switching operation.

  The drive power supply voltage Vcc for the microcomputer 50, the charging current control means 60, the charging voltage control means 80, the output voltage setting means 6, the relay control circuit 7, the battery temperature detection means 70, the battery type discrimination detection resistor 2c, etc. is a commercial AC power supply. 1 is supplied by a constant voltage power supply (second power supply circuit) 100 that is branched and formed from a first rectifying and smoothing circuit 10 that rectifies 1. The constant voltage power supply 100 is provided as a second power supply circuit of a different system from the charging power supply means 300 that is the first power supply circuit.

  The constant voltage power supply 100 includes a power supply transformer 102, a switching power supply IC 101 provided in a closed circuit of the primary coil 102a of the power supply transformer 102, and a pulse voltage generated by the switching power supply IC 101 as a secondary coil 102b of the power supply transformer 102. Rectifier diode 103 and smoothing capacitor 104 rectified on the side, feedback circuit device 105, shunt regulator 106, voltage dividing resistors 107 and 108 for setting the output voltage, and smoothing capacitor 109, and a three-terminal regulator 110 And a constant voltage output circuit for outputting a constant voltage Vcc comprising a smoothing capacitor 111 and a reset IC 112 provided on the constant voltage output side. The reset IC 112 of the constant voltage power supply 100 has a function of outputting a reset signal to the reset input port 55 in order to put the microcomputer 50 in an initial state when the power is turned on.

  The DC power supply circuit 90 is a power supply circuit for driving the PWM control IC 23, and includes a rectifying diode 91 and a smoothing capacitor 93 connected to the second secondary coil 92 of the power transformer 102. The charging power supply means 300 is configured as a separate power supply circuit.

  Next, the operation of the above-described charging apparatus according to the present invention will be described with reference to the circuit diagram shown in FIG. 1 and the control flowchart shown in FIG.

  When the power is turned on, in step 201, the microcomputer 50 enters a mounting standby state in which it waits for the battery pack 2 to be charged to be electrically connected to the charging device 200. Whether or not the battery pack 2 is connected (mounted) is determined by taking the detection signals from the battery voltage detection means 8 and the battery temperature detection means 70 into the A / D converter 52 of the microcomputer 50.

  When the battery pack 2 is connected, in step 202, the battery voltage before charging (before the relay 121 is turned on) is taken into the A / D converter 52 of the microcomputer 50 by the battery voltage detection means 8.

  Next, in step 203, the microcomputer 50 outputs the output voltage (voltage of the output terminal 3a) of the charging power source means 300 in accordance with the battery voltage of the battery pack 2 before charging detected in step 202. The output level of the digital control signal of each of the plurality of output ports 53f to 53i electrically connected to the voltage setting means 6 is set to low output (L level) or high impedance output (H level). FIG. 4 shows an example of the set voltage set according to the magnitude of the battery voltage before charging and the output level of the digital control signal required for the plurality of output ports 53f to 53i to output the set voltage. The setting example of the set voltage and the signal level of the output port is set in the same manner as the example shown in FIG.

  In step 203, setting the output voltage according to the battery voltage of the battery pack 2 before charging sets the output voltage of the charging power supply means 300 so that the potential difference from the detected battery voltage before charging becomes small. Means that. For example, if the battery voltage of the battery pack 2 before charging is 13V in step 202, as shown in FIG. 4, an output voltage 12.6V that reduces the potential difference from the battery voltage 13V is selected and set. The As a result, the potential difference between the output voltage of the charging power supply means 300 (voltage of the terminal 30a) and the battery voltage of the battery pack 2 is reduced, so that a transient inrush current that flows instantaneously when the relay 121 is turned on. Can be reduced. In order to reduce the potential difference between the battery voltage of the battery pack 2 and the output voltage of the charging power source means 300 before the relay 121 is turned on, that is, before charging, in this embodiment, as shown in FIG. By defining the voltage values to five reference voltages of 4.2V, 8.4V, 12.6V, 16.8V, and 25V, and comparing these reference voltages with the battery voltage of the battery pack 2 before charging. The reference voltage close to the battery voltage of the battery pack 2 is set as the output voltage value.

  If the output voltage value of the charging power source means 300 is set in step 203, the process proceeds to step 204, where an output on signal is transmitted from the output port 54 of the microcomputer 50 to the PWM control IC 23 via the charging control signal transmitting means 4, The output voltage value set in 203 is output to the output terminal 30a. As a result, during charging standby when the battery pack 2 to be charged is not mounted on the charging device 200, the output voltage of the charging power source means 300 is not generated, so that power consumption during charging standby can be reduced.

  Next, in step 205, it is determined whether or not the output voltage of the charging power supply means 300 is equal to or lower than a predetermined value. If the output voltage is a very small value when the battery pack 2 is mounted, an output voltage close to the battery voltage set in step 203 is output by turning on the output in step 204. For example, a nickel-cadmium battery having a nominal voltage of 24V is output. When a battery pack having a high battery voltage such as the battery pack of FIG. 1 is being charged or removed immediately after charging, the charged voltage may remain in the capacitor 34 of the charging power supply means 300 or the like. A time corresponding to the time constant determined by the capacitor 34 and the resistor 35 is required until the residual voltage is discharged by the discharging resistor 35. In particular, when the battery pack 2 having a relatively small battery voltage is mounted on the charging device 200 while a large voltage remains in the capacitor 34, the residual output voltage is compared according to the battery voltage before charging set in step 203. A time corresponding to a time constant determined by the capacitor 34 and the resistor 35 is required until the output voltage decreases to a value that is less than the target value. Therefore, step 205 is a step provided to confirm whether or not the actual output voltage of the charging power supply means 300 (the voltage of the capacitor 34) is close to the battery voltage of the battery pack 2. If the output voltage is equal to or higher than a predetermined value, the process waits until the output voltage becomes a value close to the battery voltage of the battery pack 2. For example, when the battery voltage before charging is 13V, the process waits until the actual output voltage is close to the value, for example, 14.7V. As illustrated in FIG. 5, when the output voltage (residual voltage) decreases toward the set voltage value, the output voltage (residual voltage) needs to be decreased below the set voltage according to the battery voltage before charging.

  When the actual output voltage of the charging power source 300 (the voltage of the capacitor 34) becomes equal to or lower than the set voltage value as shown in FIG. 5 in step 205, the process proceeds to step 206 and the control circuit 7 is controlled by the control signal of the output port 53. Then, the relay 121 is turned on. At this time, as shown in FIG. 6, since the potential difference Vd between the battery voltage of the battery pack 2 and the output voltage Vo of the charging power supply means 300 is set to be small, the charging power supply means 300 changes to the battery pack 2. The inrush current Id that flows transiently becomes a small value (peak value). For example, in the worst case in the conventional charging device, an inrush current (peak value) close to 100 A flows, but according to the present invention, the inrush current can be reduced to about 10 A. Thereby, destruction of the relay 121 or damage to the battery pack 2 or the like can be prevented.

  After the relay 121 is turned on in step 206, in step 207, it is determined whether or not the battery type of the battery pack 2 is a lithium ion battery. The battery type is determined by inputting the terminal voltage of the resistor 2c functioning as a battery type determining element to the A / D converter 52 of the microcomputer 50.

  If it is determined in step 207 that the battery pack 2 is a lithium ion battery, the process proceeds to step 208, and the output voltage setting means 6 performs the operation according to the number of battery cells in the battery pack 2 as shown in FIG. The output voltage of the charging power supply means 300 is reset. For example, as shown in FIG. 3, when the number of lithium ion batteries in the battery pack 2 is 3, the set output voltage is 12.6 V and is output from the output ports 53 f to 53 i of the microcomputer 50 to the output voltage setting means 6. As for the output level of the control signal, the port 53h is low output (L), and the other ports 53f, 53g and 53i are high impedance output (H). As a result, as shown in FIG. 7, constant current / constant voltage control charging is performed.

  Next, in step 209, it is determined whether or not the battery is fully charged. For example, in the constant current / constant voltage control as shown in FIG. 7, the full charge is determined based on whether or not the value of the charging current is below a predetermined value in the constant voltage section.

  If it is determined in step 207 that the battery pack 2 is a nickel metal hydride battery or a nickel cadmium battery other than a lithium ion battery, the process proceeds to step 210 to output the output voltage in order to perform charging with constant current control as shown in FIG. The setting means 6 resets the output voltage of the charging power supply means 300 to the set value 25V. In the present embodiment, the maximum rechargeable battery voltage is assumed to be 14.4V.

  Next, in step 211, it is determined whether or not the battery pack 2 is fully charged. There are various known detection methods for determining full charge when the battery pack 2 is a nickel metal hydride battery or a nickel cadmium battery. One well-known representative example is that the battery voltage of the battery pack 2 is detected by the battery voltage detecting means 8 and the battery voltage is monitored, while detecting that the battery pack 2 has fallen a predetermined amount from the peak value at the end of charging. There is -ΔV (minus delta buoy) detection for charging. As another detection method, in order to reduce overcharge by stopping charging before the battery voltage reaches the peak value and improve the cycle life of the battery pack, the second-order differential value due to battery voltage time is negative. The second-order differential detection for determining that the battery pack 2 is fully charged and detecting that the temperature rise value of the battery pack 2 from the start of charging is equal to or higher than a predetermined temperature rise value based on the output of the battery temperature detection means 70 ΔT detection for determining full charge, or battery temperature increase rate per predetermined time during charging as described in JP-A-62-193518, JP-A-2-24639, and JP-A-3-34638 There is dT / dt detection that detects that the (temperature gradient) is equal to or higher than a predetermined value and determines that the battery is fully charged. One or more of these known full charge detection methods are used to determine full charge. Door can be.

  If it is determined in step 209 or 211 that the battery is fully charged, first, in step 212, an output is sent from the output port 54 of the microcomputer 50 to the PWM control IC 23 via the charge control signal transmission means 4 in order to stop the operation of the PWM control IC 23. An off signal is transmitted, and the output voltage of the charging power supply means 300 is turned off.

  Next, in step 213, the relay 121 is turned off from the output port 53 of the microcomputer 50 via the relay control circuit 7.

  Further, in step 214, it is determined whether or not the battery pack 2 has been removed from the charging device 200. If the battery pack 2 has been removed (in the case of YES), charging has been completed, so the newly mounted battery pack 2 is charged. Accordingly, the process returns to step 201.

  As will be apparent from the above description of the embodiment, according to the present invention, when the battery pack 2 to be charged is mounted on the charging device 200, when the switch means 121 is off, the charging power supply means 300 Output voltage Vo (see FIG. 6) is set in advance to a voltage value corresponding to the battery voltage before charging of the battery pack 2 so that the battery voltage and potential difference Vd of the battery pack 2 to be charged become small. Thereafter, since the switch means 121 inserted in the charging current path of the charging power supply means 300 is turned on, the inrush current Id (see FIG. 6) flowing in the charging current path when the switch means 121 is on-controlled can be reduced. Thereby, destruction of the switch means 121 or damage to the battery pack 2 can be prevented. On the other hand, when charging is started with the switch means 121 turned on, the output voltage of the charging power supply means 300 is reset according to the battery type of the battery pack 2, so that predetermined charging control can be performed. Furthermore, according to the charging device of the present invention, when the battery pack 2 to be charged is mounted on the charging device 200, the output voltage of the charging power source means 300 is output according to the battery voltage of the battery pack 2 before charging. In addition, it is possible to reduce the power consumption of the charging device during charging standby. In particular, according to the present invention, since the charging power supply means 300 supplies the charging voltage after detecting that the battery pack 2 is mounted, the output voltage can be set to an appropriate value and the battery pack 2 is mounted. Until then, the output voltage of the charging power supply means 300 can be set to substantially zero.

  In the above embodiment, the lithium ion battery has been described as an example of the lithium battery as the battery type of the battery pack to be charged by constant current / constant voltage control. However, the present invention is applied to a charging device for charging other lithium battery types. However, the same effect can be obtained.

  Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. It is.

The circuit diagram of the charging device which concerns on one Embodiment of this invention. The flowchart which shows the charge control system by the charging device shown in FIG. The characteristic view which shows the relationship between the battery type by the charging device shown in FIG. 1, and an output setting voltage. The characteristic view which shows the relationship between the battery voltage by the charging device shown in FIG. 1, and an output setting voltage. The characteristic view which shows the relationship between the battery voltage by the charging device shown in FIG. 1, and an output setting voltage. The characteristic view which shows the time-dependent change of the inrush current by the charging device shown in FIG. The charge characteristic figure which shows constant current and constant voltage charge control. The charge characteristic figure which shows constant current charge control.

Explanation of symbols

1: Input commercial power source 2: Battery pack 2a: Battery cell 2b: Temperature sensitive element 2c: Battery type discriminating element 3: Current detection resistor 4: Charge control signal transmission means (photocoupler) 5: Charge feedback signal transmission means (photocoupler)
6: Output voltage setting means 6a-6e: Fixed resistance 6f-6i: Variable resistance 7: Relay control circuit 7a: Transistor 7b, 7c: Biasing resistor 8: Battery voltage detection means 8a, 8b: Voltage dividing resistor 9: Output voltage Detection means 9a, 9b: voltage dividing resistor 10: first rectifying / smoothing circuit 11: full-wave rectifying circuit 12: smoothing capacitor 20: switching power supply circuit 21: high-frequency transformer 22: MOSFET
23: PWM control IC 30: second rectifying / smoothing circuit 30a: output terminals 31, 32: rectifying diode 33: choke coil 34: smoothing capacitor 35: discharging resistor
40: output voltage detecting means (for feedback) 41, 42: voltage dividing resistor 50: microcomputer (microcomputer) 51: central processing unit (CPU)
52: A / D converter 53: Output port 54: Output port 55: Reset input port 60: Charging current control means 61a, 61b: operational amplifier 62, 64: operational amplifier input resistor 63, 65: operational amplifier feedback Resistance 66, 67: Charge current setting voltage dividing resistor 68: Resistance 69: Diode 70: Battery temperature detecting means 71, 72: Voltage dividing resistance 80: Charging voltage control means (output voltage control means)
81: operational amplifier 82, 83: operational amplifier input resistor 84: operational amplifier feedback resistor 85: resistor 86: diode 90: DC power supply circuit 91: rectifier diode 92: secondary coil of power transformer 93: smoothing Capacitor 100: Constant voltage power supply (second power supply circuit) 101: Switching power supply IC
102: power transformer 102a: primary coil 102b of the power transformer 102: secondary coil of the power transformer 103: rectifier diode 104: smoothing capacitor 105: feedback circuit device 106: shunt regulator 107, 108: voltage dividing resistor 109: smoothing Capacitor 110: Three-terminal regulator 111: Smoothing capacitor 112: Reset IC 120: Detection resistor 121: Relay switch 121a: Driving coil 200 of the relay switch: Charging device 300: Charging power source means (first power circuit)

Claims (7)

A charging device capable of charging a plurality of types of battery packs having different battery voltages, including a lithium battery, a nickel metal hydride battery, or a nickel-cadmium battery, and charging power supply means for supplying an output voltage for charging the battery pack; Output voltage setting means for setting the output voltage of the charging power supply means to a plurality of voltage values, and connected between the charging power supply means and the battery pack, between the charging power supply means and the battery pack Switch means for turning on or off the charging flow path, a microcomputer for controlling the switch means on or off, and battery voltage detection means for detecting the battery voltage of the battery pack,
When the battery pack to be charged is a lithium battery, the output voltage setting means sets the output voltage of the charging power supply means to a predetermined voltage value that can be charged by constant current / constant voltage control, and the battery to be charged When the pack is a nickel metal hydride battery or a nickel cadmium battery, it is configured to set the output voltage of the charging power source to a predetermined voltage value that can be charged by constant current control,
The output voltage setting means sets the output voltage of the charging power supply means to a predetermined voltage corresponding to the battery voltage of the battery pack detected by the battery voltage detection means when the switch means is in an off state; and The output voltage setting means performs charging by setting the output voltage of the charging power supply means to a predetermined voltage higher than the battery voltage to be charged in the battery pack when the switch means is in an ON state. Charging device.   A driving power source for driving the microcomputer, the output voltage setting means, the switch means, and the battery voltage detecting means is provided as a separate power source independent from the charging power means, and the battery pack to be charged is 2. The charging device according to claim 1, wherein when not mounted, the output of the charging power supply means is stopped. A charging device capable of charging a plurality of types of battery packs with different battery voltages and charging with constant current / constant voltage control or constant current control with a single charging device,
Charging power supply means for supplying charging power to the battery pack to be charged;
A switching unit that is inserted into a charging current path between the charging power source unit and the battery pack, and controls the on / off of the charging current path;
Output voltage detection means for detecting the output voltage of the charging power supply means;
Battery voltage detecting means for detecting the battery voltage of the battery pack;
Charging current control means that is electrically connected to the charging power supply means and controls a charging current flowing through the battery pack;
Output voltage control means electrically connected to the charging power supply means, and including output voltage setting means for controlling the output voltage of the charging power supply means to a predetermined voltage corresponding to the battery voltage of the battery pack;
A microcomputer that receives a detection signal including output signals of the output voltage detection means and the battery voltage detection means, and controls the switch means and the output voltage control means;
The output voltage control means sets the output voltage of the charging power supply means to a predetermined voltage corresponding to the battery voltage of the battery pack detected by the battery voltage detection means when the switch means is in an off state; and The output voltage control means performs charging by setting an output voltage of the charging power supply means to a predetermined voltage higher than a battery voltage to be charged in the battery pack when the switch means is in an ON state. Charging device.   A driving power source for driving the microcomputer, the output voltage setting means, the switch means, and the battery voltage detecting means is provided as a separate power source independent from the charging power means, and the battery pack to be charged is 4. The charging device according to claim 3, wherein when not mounted, the output of the charging power supply means is stopped.   A battery pack detection means for detecting a plurality of types of battery packs that are different in battery voltage and are charged by constant current / constant voltage control or constant current control is incorporated in the battery pack, and the microcomputer 5. The charging device according to claim 3, wherein the type of the battery pack is determined based on a detection signal detected by the battery pack detection means.   6. The switch means according to claim 3, wherein the switch means comprises a relay switch, and a switch control circuit including a control coil of the relay switch is on / off controlled by the microcomputer. Charging device. 7. The battery pack according to claim 3, wherein the battery pack is a lithium battery that is charged by constant current / constant voltage control, and a nickel-metal hydride battery and a nickel-cadmium battery that are charged by constant current control. The charging device described in one.

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