JP2012005288A - Charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charger capable of charging a battery pack with comparatively large current and suppressing breakage of a circuit component in the charger which charges the battery pack.SOLUTION: The charger includes: a charging circuit which supplies charging current to a secondary battery 40; a charging current control means 5 for controlling the charging current which flows to the charging circuit; and a component temperature detection means 34 for detecting temperature of a circuit component 12 which constitutes the charging circuit, in which the temperature of the circuit component 12 detected by the component temperature detection means 34 reaches first temperature, the charging current control means 5 sets the charging current which flows to the charging circuit smaller than when the temperature of the circuit component is equal to or less than the first temperature.

Description

  The present invention relates to a charging device for charging a secondary battery such as a nickel cadmium battery.

  In portable devices such as cordless electric tools, battery packs composed of nickel cadmium batteries (nickel cadmium batteries), nickel metal hydride batteries, and lithium ion batteries are generally used. Conventionally, a charging device for charging a battery pack composed of a nickel cadmium battery, a nickel metal hydride battery, or a lithium ion battery uses a commercial power source as an input power source.

  However, when the cordless power tool is used in a place where there is no commercial power supply, it is necessary to prepare a large number of spare battery packs when the amount of work is large. This makes it difficult to carry the battery pack.

  Therefore, a charging device configured to be charged by a power source other than a commercial power source has been proposed as an input power source of a charging device that charges the battery pack. For example, Patent Literature 1 and Patent Literature 2 disclose a charging device that uses a DC power source such as an automobile battery as an input power source in addition to a commercial power source.

JP 2005-245145 A JP 2008-236878 A

  In a charging device that can charge a battery pack for a cordless power tool, an ability to charge the battery pack with a certain amount of current is required.

  This is because, as a method of using the charging device, it is common to charge a spare battery pack while the worker is working at the work site, and until the worker uses up the capacity of one battery pack, This is because it is desirable that charging of the spare battery pack is completed.

  However, in a known charging device that can use a commercial power source and a DC power source (hereinafter referred to as a DC power source) such as an automobile battery as an input power source, the size of the charging device is small because it does not make it difficult to carry it to the work site. In order to make the sheath shape equivalent to that of a charging device using a single input power supply, it is difficult to increase the charging current particularly when a DC power supply is used.

  This is because a relatively large input current is required and a load on the charging device is larger when a DC power source is used than when a commercial power source is used. Especially when the temperature is high, the temperature in the vehicle may exceed 40 degrees, and the temperature of the components of the charging device may be relatively high due to the ambient temperature.

In addition, such a charging device that can use a plurality of input power supplies has a larger number of parts compared to a charging apparatus that uses a single input power supply, and the density of parts increases if an attempt is made to reduce the size. It is disadvantageous for heat dissipation of parts.
When the density of parts increases, for example, heat generated by power loss of a power element such as a switching element that switches main power is easily transmitted to other parts having a relatively low rated operating temperature. For this reason, the charging current cannot be easily increased.

  For the above reasons, a charging device using a DC power source as an input power source is difficult to increase the charging current. However, when the ambient temperature is relatively low or the load on the charging device is relatively small, Even when there is a large margin for the temperature rise, charging the battery pack with a uniformly small charging current increases the charging time, which is inconvenient for the operator.

  Accordingly, it is an object of the present invention to provide a charging device that can charge a battery pack with a relatively large current, particularly in a charging device that can use a DC power source such as an automobile battery in addition to a commercial power source as an input power source. It is another object of the present invention to provide a charging device that can prevent a temperature rise of a component and protect the component when the temperature rise of the component of the charging device becomes relatively high due to the influence of an ambient temperature or the like.

  In order to solve the above problems, the present invention provides a charging circuit for supplying a charging current to a secondary battery, charging current control means for controlling the charging current flowing in the charging circuit, and circuit components constituting the charging circuit. Component temperature detection means for detecting temperature, and when the temperature of the circuit component detected by the component temperature detection means reaches a first temperature, the charging current control means flows into the charging circuit. The charging current is set smaller than when the temperature of the circuit component is equal to or lower than the first temperature.

  With such a configuration, the secondary battery can be charged with a large charging current as long as the circuit components of the charging device do not reach a high temperature, so the charging time can be shortened without increasing the size of the device. Can be improved. Further, when the temperature of the circuit component becomes high, the charging current is reduced, so that an increase in the temperature of the circuit component can be suppressed, and damage to the circuit component can be suppressed.

  Further, after the charging current is reduced, when the temperature of the circuit component rises by a predetermined amount or more than the first temperature, the supply of the charging current is stopped, and the temperature of the circuit component becomes the first temperature. It is preferable to supply a charging current when the voltage drops to a maximum.

  With such a configuration, when there is a temperature rise despite the reduction in the charging current, the temperature rise of the circuit components can be suppressed by temporarily stopping the charging current. Further, since charging is resumed when the temperature drops after the charging current is stopped in the middle of charging, damage to circuit components due to high temperatures can be protected.

  Further, when the temperature rise of the circuit component after reducing the charging current is less than a predetermined value from the first temperature, the charging circuit preferably supplies the reduced charging current.

  With such a configuration, the charging can be continued when the temperature rise of the circuit components is small, and therefore there is no charging stop period, so that the charging time can be shortened and workability can be improved. .

  The charging circuit includes an AC charging circuit that supplies a charging current from an AC power source, and a DC charging circuit that supplies a charging current from a DC power source, and the component temperature detecting means constitutes at least the DC charging circuit. It is preferable to detect the temperature of the circuit component.

  With such a configuration, it is possible to detect the circuit component temperature of the DC charging circuit when using a DC power supply that requires an input current than when using an AC power supply. For this reason, even if charging is performed with a somewhat large charging current, the charging current can be reduced before the circuit component is damaged, and thus the circuit component can be protected.

  In addition, when the DC power supply is an automobile battery, the temperature inside the vehicle may be high, but even if the circuit component becomes hot according to the vehicle temperature, charging is performed while protecting the circuit component from damage. Can continue.

  In addition, in a charger equipped with an AC charging circuit and a DC charging circuit, the density of circuit components increases, and when some of the circuit components become hot, other components may become hot. By detecting the temperature, the charging current can be set to a value that can suppress the temperature rise, and the charging current can be optimized according to the temperature.

  According to the present invention, as long as the temperature of the circuit components of the charging device does not become relatively large due to the influence of the ambient temperature or the like, charging can be performed with a relatively large charging current, so that the charging time can be shortened and workability can be improved. be able to.

  In addition, when the temperature of the circuit component of the charging device reaches a predetermined value or more due to the influence of the ambient temperature or the like, the charging current is set to a small value according to the temperature of the component or the charging is temporarily stopped. Circuit components can be protected.

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

It is a circuit block diagram of the charging device which concerns on embodiment of this invention, Comprising: The circuit block diagram which shows the state which connected the nickel cadmium battery or the nickel metal hydride battery. It is a circuit block diagram of the charging device which concerns on embodiment of this invention, Comprising: The circuit block diagram which shows the state which connected the lithium ion battery. The control flowchart for controlling operation | movement of the charging device shown in FIG. The control flowchart for controlling operation | movement of the charging device shown in FIG.

Hereinafter, an embodiment according to the charging device of the present invention will be described with reference to FIGS. 1 to 4. 1 and 2 are circuit block diagrams of the charging device of the present invention, and FIGS. 3 and 4 are control flowcharts when the battery pack is charged by the charging device of the present invention. Note that in the drawings for describing the embodiments, members having the same functions or elements are denoted by the same reference numerals, and repeated description thereof is omitted.

  First, an overall configuration of the charging device 1 according to the present invention will be described with reference to a circuit block diagram of the charging device 1 shown in FIGS. 1 and 2. The charging device 1 is a charging device that can use a commercial power source 2 and a DC power source 3 such as an automobile battery as input power sources.

  In the first embodiment shown in FIG. 1, when the battery pack 40 made of a nickel-cadmium battery, a nickel-metal hydride battery, or the like used for a cordless power tool is connected to the charging device 1 for charging, the second embodiment shown in FIG. The embodiment shows a case where a battery pack 50 made of a lithium ion battery is connected to the charging device 1 for charging. In the first and second embodiments, the battery pack to be connected (charged) is different, but the circuit configuration of the charging device 1 is the same.

  The charging device 1 is configured so that a commercial power source 2 or a DC power source 3 such as a car battery can be connected as an input power source. When connecting the DC power source 3 to the charging device 1, a DC cable (not shown) is connected to the DC connector 4 of the charging device 1.

  In the first embodiment shown in FIG. 1, the battery pack 40 includes a unit cell set 40 a composed of, for example, a unit cell of a nickel-cadmium battery or a nickel-metal hydride battery, and a battery type of a nickel-cadmium battery or nickel-metal hydride battery constituting the unit cell set 40 a And an identification resistor 40b for identifying the number of battery cells (number of unit cells) and a thermistor 40c for detecting the temperature of the unit cell set 40a. The battery pack 40 is electrically connected to the charging device 1 by a terminal portion 40d including a plurality of terminals including a plus terminal (+), a minus terminal (−), a temperature terminal (S), an identification terminal (T), and the like. Yes.

  The thermistor 40c is a thermal element provided in contact with or close to the unit cell set 40a in order to detect the battery temperature during charging of the unit cell set 40a. The battery temperature detection information by the thermistor 40 c is input to the microcomputer 5 of the charging device 1 via the first battery temperature detection means 6 of the charging device 1.

  On the other hand, in the second embodiment shown in FIG. 2, the battery pack 50 includes a unit cell set 50a made of, for example, a lithium ion battery unit, a protection IC 50b, and a thermal protector 50c that prevents an abnormal temperature rise during charging. An identification resistor 50d for identifying the battery type and the number of battery cells (number of unit cells) of the lithium ion battery (unit cell) constituting the unit cell set 50a, and a thermistor 50e for detecting the temperature of the unit cell set 50a The overcharge signal transmission means 50f outputs an overcharge signal to the overcharge signal transmission terminal LE in response to a signal from the protection IC 50b. The battery pack 50 is charged by a terminal portion 50g including a plurality of terminals including a plus terminal (+), a minus terminal (−), a temperature terminal (LS), an identification terminal (T), an overcharge signal terminal (LE), and the like. 1 is electrically connected.

  The type of the battery pack 50 is detected by the resistance value of the identification resistor 50d set in advance corresponding to the type of the battery pack 50. The identification resistor 50d is electrically connected to the battery type identification means 8 of the charging device 1 and is compared with an identification value corresponding to the battery type stored in advance in the microcomputer 5 of the charging device 1 to be identified as a specific one. With this identification resistor 50d, the charging condition of the charging device 1 can be set according to the type of the battery pack 50 connected to the charging device 1.

  The thermal protector 50c incorporated in the battery pack 50 is provided in the charging path, and includes a temperature sensitive switch using a bimetal contact that deforms in response to the temperature generated by the unit cell set 50a. The temperature of the unit cell set 50a When the temperature reaches a predetermined temperature or higher (for example, 80 degrees or higher), the charging path is cut off. After the interruption, when the temperature of the unit cell set 50a is lowered to a predetermined temperature or lower, the charging path is connected again. The thermal protector 50c is connected so as to achieve a double protection function against the battery temperature together with the function of the thermistor 50e.

  The thermistor 50e is a thermal element provided in contact with or close to the unit cell set 50a in order to detect the battery temperature during charging of the unit cell set 50a. The battery temperature detection information by the thermistor 50e is input to the microcomputer 5 of the charging device 1 via the second battery temperature detection means 7 of the charging device 1.

  The unit cell set 50e is controlled by the protection IC 50b so as not to be overcharged and overdischarged (or overcurrent). For this control, the protection IC 50b includes an overcharge detection circuit and an overdischarge / overcurrent detection circuit for monitoring the terminal voltage and load current of each cell of the unit cell set 50a. When the battery pack 50 is connected to the cordless power tool and an overdischarge or overcurrent state is detected by the protection IC 50b, a control signal is output from the discharge stop signal terminal LD of the battery pack 50 to the power tool side, and the operation of the power tool is performed. Operates to stop. At the time of charging, when the protection IC 50b detects overcharge, the overcharge signal output from the overcharge signal transmission means 50f is input to the overcharge detection circuit 9 and the microcomputer 5 of the charging device 1.

  The battery pack 40 and the battery pack 50 have different terminals connected to the charging device 1. For example, the charging device 1 is provided with two battery temperature detecting means as described later, and one is connected to the battery pack 40 and the other is connected to the battery pack 50. This is due to the difference in the charging method of the battery pack. In addition, the battery pack 50 made of a lithium ion battery is provided with a charging plus terminal (+) and a discharging plus terminal (D +) separately, but the same terminal may be used or the minus terminal may be set separately.

  The microcomputer (microcomputer) 5 functions as a main controller of the charging device 1, and includes a first battery temperature detection means 6 connected to the AC input voltage detection circuit 25, a DC input voltage detection circuit 27, and the battery pack 40, a battery Second battery temperature detection means 7 connected to pack 50, battery type identification means 8, overcharge detection circuit 9 connected to battery pack 50, battery voltage detection circuit 28, charge current detection means 29, and component temperature detection Based on the output of the means 34, the first switching control circuit 17, the second switching control circuit 21, the display circuit 35, the fan motor drive circuit 37, and the like are controlled.

  In each input / output port of the microcomputer 5, the port A is an input port for the microcomputer 5 to read output information of the AC input voltage detection circuit 25 through the photocoupler 26. The port B is an input port for the microcomputer 5 to read output information from the DC input voltage detection circuit 27. Port C is an input port for the microcomputer 5 to read the output information of the first battery temperature detection means 6. The port D is an input port for the microcomputer 5 to read output information from the second battery temperature detection means 7. The port E is an input port for the microcomputer 5 to read output information from the battery type identification unit 8. The port F is an input port for the microcomputer 5 to read output information from the overcharge detection circuit 9. The port G is an input port for the microcomputer 5 to read output information of the battery voltage detection circuit 28. The port H is an input port for the microcomputer 5 to read output information from the charging current detection means 29. The port I is an input port for the microcomputer 5 to read output information from the component temperature detection means 34.

  The port J is an output port for outputting a signal that causes the microcomputer 5 to operate the first switching control circuit 17 when the commercial power source 2 is used to charge the battery pack 40. The port K is an output port for outputting a signal for causing the microcomputer 5 to operate the first switching control circuit 17 when the commercial power source 2 is used to charge the battery pack 50. The port L is an output port for outputting a signal for causing the microcomputer 5 to operate the second switching control circuit 21 when the battery pack 40 is charged using the DC power supply 3. The port M is an output port for outputting a signal for causing the microcomputer 5 to operate the second switching control circuit 21 when the battery pack 50 is charged using the DC power supply 3. The port N is an output port for outputting a signal for the microcomputer 5 to set a charging current. The port O is an output port for outputting a signal for causing the microcomputer 5 to operate the display circuit 35. The port P is an output port for outputting a signal for causing the microcomputer 5 to operate the cooling fan drive circuit 37.

  The first battery temperature detection means 6 is composed of a resistor, functions for a nickel-cadmium battery and a nickel-metal hydride battery, and outputs a voltage corresponding to temperature information from the thermistor 40 c of the battery pack 40 to the microcomputer 5. Further, when the temperature of the battery pack 40 exceeds a predetermined value, the first battery temperature detecting means 6 cuts off the output signal from the port J and the port L of the microcomputer 5, and the first switching control circuit 17 and the second switching control circuit 17. It also has a function of forcibly stopping the switching control circuit 21.

  The second battery temperature detecting means 7 functions for the lithium ion battery and outputs a voltage corresponding to temperature information from the thermistor 50 e of the battery pack 50 to the microcomputer 5. Further, when the temperature of the battery pack 50 exceeds a predetermined value, the second battery temperature detecting means 7 cuts off the output signal from the port K and the port M of the microcomputer 5, and the first switching control circuit 17 and the second battery temperature detecting means 7 It also has a function of forcibly stopping the switching control circuit 21.

  In the charging device 1 of the present embodiment, the battery temperature detection means is separated from the battery temperature detection means 6 and 7 so as to correspond to the battery packs 40 and 50, respectively. Thereby, it can be determined which battery pack is connected to the charging device 1, and an optimal charging method can be applied to each of the battery packs 40 and 50.

  The battery type identification means 8 outputs a voltage corresponding to the resistance value of the identification resistors 40b and 50d provided corresponding to the battery type to the microcomputer 5.

  The overcharge detection circuit 9 functions with respect to the lithium ion battery, and has a function of transmitting an overcharge signal from the protection IC 50b of the battery pack 50 and the overcharge signal transmission means 50f to the microcomputer 5 and stopping charging.

  A high-frequency transformer (switching transformer) 10 is charged by being electromagnetically coupled to two input windings 10a and 10b provided corresponding to the input power sources of the commercial power source 2 and the DC power source 3 and these input windings. And a charging output winding 10c for outputting a voltage for use. Since the transformer 10 is a component that occupies a relatively large area in the charging device 1, according to the present invention, a single transformer is used for a plurality of input power sources.

  The first smoothing circuit 11 forms an input circuit coupled to the input winding 10a of the transformer 10, and includes a rectifying diode (not shown) for rectifying and smoothing the commercial power supply 2 and a smoothing capacitor. The commercial power source 2 is full-wave rectified by the first smoothing circuit 11 and the rectified voltage is smoothed to a DC voltage.

  The second smoothing circuit 12 forms an input circuit coupled to the input winding 10b of the transformer 10, and includes a smoothing capacitor 12a for smoothing an input voltage input from the DC power supply 3, and a backflow prevention diode 12b. Become.

  The third smoothing circuit 13 is a smoothing circuit including a rectifier circuit formed in the charging output winding 10 c of the transformer 10. This circuit outputs a DC voltage for charging the battery packs 40 and 50.

  The auxiliary power circuit 14 includes a transformer (not shown), a switching element, a switching control circuit, and an output smoothing circuit, converts the output from the first smoothing circuit 11, and drives the entire control circuit of the charging device 1. It is the power supply circuit used as the electric power supply source for this. When the commercial power supply 2 is used as an input power supply, the DC output from the auxiliary power supply circuit 14 is adjusted to a predetermined DC voltage by the constant voltage circuit 15 and is used as a drive power supply Vcc (for example, 5 V) of a control circuit including the microcomputer 5. Supplied. Further, the DC output from the auxiliary power circuit 14 is supplied via the first power transmission circuit 19 as a driving power source for the first switching control circuit 17 when charging the battery packs 40 and 50 using the commercial power source 2 as an input power source. It is supplied to the first switching control circuit 17.

  On the other hand, when the DC power supply 3 is used as the input power supply, the DC output voltage of the second smoothing circuit 12 is supplied via the backflow prevention diode 16 and the constant voltage circuit 15 to the drive power supply Vcc of the control circuit including the microcomputer 5. Supplied as

  The constant voltage circuit 15 is composed of, for example, a constant voltage IC (not shown), an electrolytic capacitor, and the like, and supplies a voltage that is constantly adjusted as the drive power supply Vcc to the control circuit including the microcomputer 5 as described above.

  The backflow prevention diode 16 is provided to prevent the output voltage of the auxiliary power supply circuit 14 from being applied to the DC input voltage detection circuit 27 when the commercial power supply 2 is used as an input power supply.

  The first switching control circuit 17 supplies a driving pulse for switching the first switching element 18 and controls the pulse width of the driving pulse. Thereby, the voltage generated in the output winding 10c of the transformer 10 is controlled, and the output voltage of the third smoothing circuit 13 is adjusted.

  The first switching element 18 is composed of, for example, a power MOSFET (power insulated gate field effect transistor). The drain and source terminals of the first switching element 18 are connected in series to the input winding 10a, and the DC output voltage of the first smoothing circuit 11 is switched and supplied to the input winding 10a.

  The first power transmission circuit 19 is a circuit composed of a MOSFET, a resistor, and a zener diode (not shown), and turns on / off the power supply from the auxiliary power circuit 14 to the first switching control circuit 17. The first power transmission circuit 19 is turned on and off by the output signal of the microcomputer 5 (port J or K) transmitted through the photocoupler 20. The photocoupler 20 transmits the output signal of the microcomputer 5 (port J or K) to the first power transmission circuit 19.

  The second switching control circuit 21 supplies a driving pulse for switching the second switching element 22 and controls the pulse width of the driving pulse. Thereby, the voltage generated in the output winding 10c of the transformer 10 is controlled, and the output voltage of the third smoothing circuit 13 is adjusted.

  Similar to the first switching element 18, the second switching element 22 is made of, for example, a power MOSFET. The drain and source terminals of the second switching element 22 are connected in series to the input winding 10b, and the DC output voltage of the second smoothing circuit 12 is switched and supplied to the input winding 10b via the backflow prevention diode 23.

  The reverse current prevention diode 23 is an electromotive force induced in the input winding 10b according to the turn ratio of the input winding 10a and the input winding 10b of the transformer 10 when the commercial power supply 2 is used to charge the battery pack. Therefore, it is provided to prevent a large current from flowing through a parasitic diode (not shown) of the second switching element 22 formed of a MOSFET.

  The second power transmission circuit 24 is a circuit composed of a MOSFET and a resistor (not shown), and turns on and off the power supply from the second smoothing circuit 12 to the second switching control circuit 21. The second power transmission circuit 24 is turned on and off by the output signal of the microcomputer 5 (port L or M).

  The AC input voltage detection circuit 25 is a detection circuit for recognizing that commercial power (AC power) is input to the charging device 1. The detected AC input voltage detection information is input to the microcomputer 5 (port A) via the photocoupler 26. The photocoupler 26 transmits the output signal of the AC input voltage detection circuit 25 to the microcomputer 5 (port A).

  The DC input voltage detection circuit 27 is composed of a voltage dividing resistor (not shown), for example, and is a detection circuit for recognizing that the DC power supply 3 is connected to the DC connector 4 and detecting the value of the input voltage of the DC power supply 3. is there. The DC input voltage detection information detected here is input to the microcomputer 5 (port B).

  The charging device 1 selects either the commercial power source 2 or the DC power source 3 as the input power source of the charging device 1 based on the detection signals of the AC input voltage detection circuit 25, the DC input voltage detection circuit 27, and both detection circuits. To do.

  The battery voltage detection circuit 28 is a detection circuit for detecting the value of the battery voltage of the battery packs 40 and 50, and includes a resistor. The battery voltage detection information detected here is input to the microcomputer 5 (port G).

  The charging current detection means 29 comprises, for example, a shunt resistor inserted in the charging path and a differential amplifier circuit using an operational amplifier, detects a voltage generated by the charging current flowing through the charging current detection means 29, and responds to the charging current. The output signal is transmitted to the microcomputer 5 (port H) and the constant current control circuit 31.

  The charging current setting unit 30 is composed of a plurality of voltage dividing resistors (not shown), and is a circuit that sets an operation reference value of the constant current control circuit 31. This reference value is set by the output signal of the microcomputer 5 (port N), and an optimum charging current is selected according to the type of input power source, the type of battery, the state of the battery, and the state of the charging device 1.

  The constant current control circuit 31 includes a comparison circuit using an operational amplifier (not shown). The constant current control circuit 31 outputs a feedback signal based on the comparison between the output signal of the charging current detection unit 29 and the reference voltage of the charging current setting circuit 30 to the first switching control circuit 17 and Output to the second switching control circuit 21. The photocouplers 32 and 33 transmit the feedback signals from the constant current control circuit 31 to the first switching control circuit 17 and the second switching control circuit 21, respectively.

  The component temperature detection means 34 includes a thermistor 34a and a resistor 34b, and detects the temperature of a predetermined component. This temperature information is input to the microcomputer 5 (port I). The thermistor 34a is provided in contact with or close to the smoothing capacitor 12a of the second smoothing circuit 12, for example. Here, as an example of the installation location of the thermistor 34a, the vicinity of the smoothing capacitor 12a is the smoothing capacitor 12a. A relatively large current flows through the backflow prevention diodes 12b and 23, the second switching element 22, etc. This is because the heat of these power elements is easily transferred to the smoothing capacitor 12a. The component temperature detecting means 34 may be provided for each component so as to detect all the temperatures of the components constituting the charging device 1, but by providing the component temperature detecting device 34 for a component having the most influence on charging. It is also effective in terms of the number of parts. When provided near the transformer 10, the upper limit temperature of the winding is about 120 ° C., so that the charging current is controlled to be small when the temperature reaches that temperature.

  The display circuit 35 is a display circuit using a light emitting element such as an LED, for example, and is a circuit for notifying an operator of the operating state of the charging device 1. The display form of the display circuit 35 changes depending on the output signal of the microcomputer 5 (port O). For example, various settings such as lighting during charging and blinking when charging is completed are possible.

  The cooling fan 36 is provided so that the battery packs 40 and 50 can be charged while cooling the battery when charging the battery packs 40 and 50 with a relatively large current. The cooling fan drive circuit 37 is composed of, for example, a MOSFET (not shown) and controls the drive of the cooling fan 36 based on the output signal of the microcomputer 5 (port P).

  Here, the charging circuit includes at least the first smoothing circuit 11, the second smoothing circuit 12, and the diode 23, the AC charging circuit includes the first smoothing circuit 11, and the DC charging circuit includes the second smoothing circuit 12 and the diode 23. The charging current control means includes at least the microcomputer 5, the charging current setting means 30, and the constant current control means 31.

Next, the operation of the charging apparatus 1 according to this embodiment will be described with reference to the circuit block diagrams shown in FIGS. 1 and 2 and the control flowchart shown in FIG.

  3 and 4, after the microcomputer 5 is started, the microcomputer 5 initializes each input / output port and the like (step 101), and displays on the display circuit 35 that "before charging is started" (step 102). Then, the first switching control circuit 17 and the second switching control circuit 21 are turned off (step 103).

  Subsequently, the microcomputer 5 determines whether or not the commercial power source 2 is input based on the output signals from the AC input voltage detection circuit 25 and the photocoupler 26 (step 104). If it is determined in step 104 that the commercial power source 2 is input, the presence / absence of input of the DC power source 3 is subsequently determined based on the output signal from the DC input voltage detection circuit 27 (step 105). If it is determined in step 105 that the DC power source 3 is not input, the operation proceeds to the alternating current (AC) mode (step 106).

  If it is determined in step 104 that the commercial power source 2 is not input (in the case of NO), it is subsequently determined whether or not the DC power source 3 is input (step 107), and if the DC power source 3 is input here. If it is determined, the process proceeds to the direct current (DC) mode (step 108).

  Next, it is determined whether or not the voltage of the DC power supply 3 is abnormal (step 109). If the voltage of the DC power supply 3 is not abnormal in step 109, the process proceeds to step 112. If the voltage of the DC power supply 3 is abnormal in step 109 (in the case of YES), the first switching control circuit 17 and the second switching control circuit 21 are turned off (step 110), and then the display circuit 35 displays the power supply abnormal state. (Step 111). This suppresses overdischarge of the DC power supply 3 by prohibiting charging of the battery packs 40 and 50 when the DC power supply 3 has an abnormally low voltage. For example, if the DC power source 3 is a car battery in an automobile, the overdischarge can be suppressed.

  If it is determined in step 105 that the DC power source 3 is input (in the case of YES), it is considered that the commercial power source 2 and the DC power source 3 are input simultaneously, and the first switching control circuit 17 and the second switching control circuit 21 is turned off (step 110), and the display circuit 35 is displayed as a power supply abnormal state (step 111). Here, when the display circuit 35 is composed of LEDs, the DC power supply abnormal state and the multiple power supply connection state may be distinguished by a combination of blinking, lighting, and the like.

  According to charging device 1 of the present invention, transformer 10 and constant current control circuit 31 are provided in common for two input power supplies (commercial power supply 2 and DC power supply 3), so both power supplies are input. In this case, since the output voltage of the third smoothing circuit 13 becomes unstable, the switching control circuits 17 and 21 of the charging device 1 are controlled so as to suppress the operation in order to avoid this. If it is determined in step 107 that the DC power source 3 is not input, the first switching control circuit 17 and the second switching control circuit 21 are turned off (step 110).

  After setting the AC mode or DC mode input mode in step 106 or step 108, the microcomputer 5 determines whether or not the battery packs 40 and 50 are connected to the charging device 1 (step 112). Is determined not to be connected to the charging device 1, the charge completion flag is reset (step 113), the charging flag is reset (step 114), and the process returns to step 102.

  If it is determined in step 112 that the battery packs 40 and 50 are connected to the charging device 1, the microcomputer 5 determines whether or not there is a charging flag (step 115). Skip to step 120.

  If it is determined in step 115 that there is no charging flag, it is determined whether or not there is a charging completion flag (step 116). If there is a charging completion flag, the microcomputer 5 returns to step 103.

  If there is no charge completion flag in step 116, the microcomputer 5 determines the battery type / number of cells based on the output of the battery type identification means 8 (step 117), and then determines the battery temperature of the battery packs 40, 50 as the battery. Determination is made based on the output of the temperature detection means 6 or 7 (step 118), and if the battery packs 40, 50 are at a high temperature, the microcomputer 5 displays the display circuit 35 as a battery high temperature state (step 119), and step 103 Return to.

  When it determines with the battery packs 40 and 50 not being high temperature in step 118 (in the case of NO), the microcomputer 5 determines whether it is AC mode (step 120). If it is determined in step 120 that the current mode is not the AC mode (NO), the microcomputer 5 proceeds to the DC mode (step 121). Subsequently, the microcomputer 5 detects that the battery pack connected to the charging device 1 is a lithium ion battery (battery pack). 50) is determined (step 122).

  If it is determined in step 122 that the battery pack is a lithium ion battery (battery pack 50), the battery type and the number of cells are determined again (step 123), and the charging voltage / current set value of the lithium ion battery in the DC mode is determined. Is set in the charging current setting means 30 (step 124).

  If it is determined in step 122 that the battery pack is not a lithium ion battery (battery pack 50), the battery pack is regarded as a nickel-cadmium battery or a nickel-metal hydride battery (battery pack 40), and the DC-mode nickel-nickel metal hydride battery is used. Are set in the charging current setting means 30 (step 125).

  In steps 124 and 125, the set values of the charging voltage and charging current are optimal based on the outputs of the AC input voltage detection circuit 25, the DC input voltage detection circuit 27, the battery temperature detection means 6 or 7, and the battery type identification means 8. A value is selected. For example, when the DC power supply 3 is input, the charging current is made smaller than when the commercial power supply 2 is input. This is an important control in the sense that it matches the capability of the DC power supply 3. Further, it is possible to determine whether the battery pack is a lithium ion battery or a nickel-cadmium nickel metal hydride battery, and to apply an optimum charge control method to each.

  After the processing of steps 124 and 126, it is determined whether or not there is a charge hold flag (step 126). If there is no charge hold flag (in the case of NO), the process proceeds to step 127, the second switching control circuit 21 is turned on, and then step Proceeding to 135, the display circuit 35 displays “charging”.

  If it is determined in step 120 that the mode is the AC mode, the process proceeds to the setting of the AC mode in step 128. Subsequently, the microcomputer 5 determines whether or not the battery pack is a lithium ion battery (battery pack 50) ( Step 129).

  When it is determined in step 129 that the battery pack is a lithium ion battery (battery pack 50), the battery type and the number of unit cells are determined again (step 130), and the charging voltage / current set value of the lithium ion battery in the AC mode is determined. Is set in the charging current setting means 30 (step 131).

  If it is determined in step 129 that the battery pack is not a lithium ion battery (battery pack 50), the battery pack is considered to be a nickel-cadmium battery or a nickel-metal hydride battery (battery pack 40), and the AC mode nicad-nickel hydride battery is used. Is set in the charging current setting circuit 30 (step 132).

  After the processing of steps 131 and 132, it is determined whether or not there is a charge hold flag (step 133). If there is no charge hold flag (NO), the process proceeds to step 134, the first switching control circuit 17 is turned on, and then step Proceeding to 135, the display circuit 35 displays “charging”.

  After the processing of step 135, the microcomputer 5 sets a charging flag (step 136), and subsequently determines whether or not there is a component high temperature flag (step 137). If there is no component high temperature flag in step 137 (in the case of NO), the microcomputer 5 determines whether the temperature of the predetermined component is high based on the output of the component temperature detection means 34 (step 138).

  In step 138, if the component temperature is not high (in the case of NO), charging is started at the predetermined set value selected in the previous step 124, 125, 131, or 132 (step 139), and the microcomputer 5 continues. Advances to the full charge detection processing step (step 147).

  If the component temperature is high in step 138, the microcomputer 5 sets a component high temperature flag, and further stores the temperature of the component at that time in a storage unit (not shown) built in or externally attached to the microcomputer 5 (step 140). . After the processing of step 140, the microcomputer 5 sets the current value at the time of high component temperature in the charging current setting circuit 30 (step 141). As the current value at this time, a current value smaller than the set value selected in the previous step 124, 125, 131, or 132 is set. This is because if the charging current is increased in a state where the component is at a high temperature, the component will be at a higher temperature and the component may be damaged.

  After the process of step 141, the microcomputer 5 determines whether or not the component temperature has increased by a predetermined value or more with respect to the component temperature stored in step 140 (step 142). Further, also when there is a component high temperature flag in the previous step 137, the microcomputer 5 proceeds to step 142 and determines whether or not the component temperature has increased by a predetermined value or more with respect to the component temperature stored in step 140.

  In step 142, if the component temperature has not increased by a predetermined value or more (in the case of NO), the microcomputer 5 proceeds to step 139 and sets the setting in step 141 for the charging condition set in step 124, 125, 131, or 132. Charging is started with the set value taken into account, and then the microcomputer 5 proceeds to the step of full charge detection processing (step 147).

  In step 142, if the component temperature has risen by a predetermined value or more, the microcomputer 5 sets the charge hold flag (step 143), and then proceeds to step 144 to display the display circuit 35 as “charge pending”. . Subsequently, the microcomputer 5 determines whether or not the component temperature has decreased to a predetermined value or less (step 145). If the component temperature has not decreased (in the case of NO), the microcomputer 5 returns to step 103 and returns to the first switching control circuit. 17. Stop the second switching control circuit 21.

  If there is a charge hold flag in steps 126 and 133, the microcomputer 5 displays "Charge hold" on the display circuit 35, and determines whether or not the component temperature has decreased to a predetermined value or less (step). 145). In step 145, when the component temperature falls below the predetermined value, the microcomputer 5 resets the charge suspension flag (step 146).

  In the full charge detection process of step 147, a well-known technique can be employed for full charge detection. For example, in the case of the battery pack 50 formed of a lithium ion battery, the charging voltage of the unit cell is controlled so as not to become a predetermined voltage value (for example, 4.2 V) or more by general constant voltage / constant current control. Specifically, in the initial charging stage, charging is performed with a predetermined charging current set in the charging current setting means 30, and when the battery voltage reaches a predetermined voltage stored in the microcomputer 5, the charging current is set. When the battery voltage reaches a predetermined voltage again, the current is changed stepwise to a smaller value. It is possible to employ a charging method and a full charging detection method in which the battery voltage is fully charged when the battery voltage reaches a predetermined voltage when the charging current is the minimum set value. Alternatively, the charging current may be decreased when the battery voltage reaches a predetermined voltage, and it may be determined that the battery is fully charged when the charging current is decreased to the full charge detection value.

  On the other hand, in the case of the battery pack 40 composed of a nickel-cadmium battery or a nickel-metal hydride battery, a -ΔV detection method (minus delta V control method) that detects when a predetermined amount has dropped from the peak voltage at the end of charging, As disclosed in Japanese Patent No. 193518, Japanese Patent Laid-Open No. 2-246739, Japanese Utility Model Laid-Open No. 3-34638, etc., the time point at which the battery temperature increase rate (temperature gradient) per predetermined time during charging suddenly increases is shown. A ΔT / Δt detection method (temperature rise gradient control method) to be detected can be employed.

  If it is not determined in step 147 that the battery pack is fully charged, the process returns to step 104. If it is determined in step 147 that the battery pack is fully charged, the component high temperature flag is reset (step 148), the charging flag is reset (step 149), and the display circuit 35 displays "charging complete". (Step 150), the charge completion flag is set (Step 151) and each process is performed, and the process returns to Step 103.

  As will be apparent from the above embodiment, according to the present invention, a relatively large charging current can be obtained unless the load on the charging device becomes excessive due to the influence of the ambient temperature or the like while suppressing an increase in the size of the charging device. The battery pack can be charged by any one of at least two input power sources including a commercial power source and a direct current power source such as an automobile battery, which is short in charging time and convenient for workers. A charging device can be provided.

  Further, according to the present invention, when the temperature of the component of the charging device becomes relatively high due to the influence of the ambient temperature or the like, the load on the charging device is reduced by reducing the charging current according to the temperature of the component. Can be made lighter and the components can be protected.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and the Nicado used as a power source for portable equipment such as a cordless electric tool. A charging device for charging battery packs composed of unit cells such as batteries, nickel-metal hydride batteries, lithium-ion batteries, etc., and in particular, multiple power sources including commercial power sources and in-vehicle DC power sources can be used as input power sources The present invention relates to protection of the components of a simple charging device, and can be changed without departing from the scope of the invention.

1 is a charging device, 2 is a commercial power supply (AC power supply), 3 is a DC power supply, 4 is a DC connector, 5 is a microcomputer, 6 is a battery temperature detection means, 7 is a battery temperature detection means, and 8 is a battery type. Identification means, 9 is an overcharge detection circuit, 10 is a transformer (switching transformer), 10a and 10b are input windings, 10c is a charge output winding, 11 is a first smoothing circuit, 12 is a second smoothing circuit, and 12a is smoothing. Capacitor, 12b is a backflow prevention diode, 13 is a third smoothing circuit, 14 is an auxiliary power circuit, 15 is a constant voltage circuit, 16 is a backflow prevention diode, 17 is a first switching control circuit, and 18 is a first switching element. , 19 is a first power transmission circuit, 20 is a photocoupler, 21 is a second switching control circuit, 22 is a second switching element, 23 is a backflow prevention diode, and 24 is a second. A source transmission circuit, 25 an alternating current (AC) input voltage detection circuit, 26 a photocoupler, 27 a direct current (DC) input voltage detection circuit, 28 a battery voltage detection circuit, 29 a charging current detection means, and 30 a charging current setting Means 31, a constant current control circuit, 32 a photocoupler, 33 a photocoupler, 34 a component temperature detection means, 34 a a thermistor, 34 b a resistor, 35 a display circuit, 36 a cooling fan, 37 a cooling fan drive circuit , 40 is a battery pack, 40a is a unit cell set, 40b is an identification resistor, 40c is a thermistor, 40d is a terminal part, 50 is a battery pack, 50a is a unit cell set, 50b is a protection IC, 50c is a thermal protector, and 50d is identification A resistor, 50e is a thermistor, 50f is an overcharge signal transmission means, and 50g is a terminal portion.

Claims (4)

A charging circuit for supplying a charging current to the secondary battery;
Charging current control means for controlling the charging current flowing in the charging circuit;
Component temperature detection means for detecting the temperature of the circuit components constituting the charging circuit,
When the temperature of the circuit component detected by the component temperature detection means reaches a first temperature, the charging current control means indicates the charging current flowing through the charging circuit, and the temperature of the circuit component is the first temperature. The charging device is characterized in that it is set smaller than when the temperature is less than or equal to.   After the charging current is reduced, when the temperature of the circuit component rises by a predetermined value or more than the first temperature, the supply of the charging current is stopped and the temperature of the circuit component is lowered to the first temperature. The charging device according to claim 1, wherein a charging current is supplied when the charging is performed.   3. The charging circuit according to claim 2, wherein the charging circuit supplies the reduced charging current when the temperature rise of the circuit component after the charging current is reduced is less than a predetermined value from the first temperature. The charging device described. The charging circuit includes an AC charging circuit that supplies a charging current from an AC power source, and a DC charging circuit that supplies a charging current from a DC power source,
4. The charging device according to claim 1, wherein the component temperature detection unit detects a temperature of at least a circuit component constituting the DC charging circuit. 5.