JPH0232856B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention divides a rechargeable battery unit formed by connecting a plurality of batteries in series into two parts, charges each divided part of the rechargeable battery unit, and after charging is completed,
This invention relates to a charging circuit that connects two divided parts of a rechargeable battery unit in series and returns them to the original rechargeable battery unit.

BACKGROUND ART Conventionally, when people carry mobile devices such as mobile phones, they often carry the mobile phones after they have been fully charged in a car. In this case, the mobile phone or the like is installed in the car and is easily attached and detached.

The power supply voltage of a mobile device installed in a car is generally the same as the car's battery voltage. Therefore, the battery voltage of an automobile is insufficient to charge a rechargeable battery that is a power source for a mobile phone or the like.

Conventionally, in order to charge power supplies for mobile phones and other devices using a car's battery, a DC/DC converter was used to boost the battery voltage. However, mobile phones and the like that have a transmission output of more than 10 W class have the disadvantage that even if a practical large-capacity DC/DC converter is used, the charging time is extremely long due to the insufficient capacity.

Rapid charging is necessary because the time a person spends in a car is generally short compared to the charging time.

As a quick charging method without using a DC/DC converter, the rechargeable battery unit is divided into two, the voltage of the rechargeable battery unit being charged is lowered, and after charging is completed, the rechargeable battery unit is divided into two again. There is a method of connecting the unit and returning it to a rechargeable battery unit with the original terminal voltage, which allows rapid charging.

FIG. 1 shows the configuration of this conventional charging circuit. When a power source such as a car battery is connected, the coil 5 (relay) is activated and switches the transfer contacts 3 and 4 connected to the positions shown in the figure so that it can be discharged when the power source is not connected. When the rechargeable battery unit 11 is divided into first and second rechargeable battery unit divided parts 11a and 11b, the above-described rapid charging can be performed by passing variable resistors 16 and 17 through the divided parts 11a and 11b, respectively. In addition, here, the variable resistor 16,
For the portion shown as 17, a transistor constituting a constant current source or a switching element for joggle charging is used.

By the way, portable car telephones and the like having such a configuration are subject to various troubles and circuit problems due to the harsh usage environment. For example, if your mobile device is accidentally dropped and subjected to mechanical shock while transmitting,
The relay contacts can momentarily open, which can reset the circuit and interrupt the call. This is because the mobile device itself uses logic such as a microcomputer. Furthermore, when the contacts separate in such a case, arc discharge occurs at the separated contacts because a large current is flowing during transmission, and the contacts may be damaged or welded. Furthermore, when used outdoors, the relay contacts may be corroded by moisture or gas, resulting in poor contact.

Furthermore, since there is a time delay between the application of voltage to the relay coil and the switching of the contacts, a diode 1 shown in FIG. 1 must be connected to protect the battery. The diode 1 needs to have a large capacity, which causes a voltage drop when the battery is discharged.

Furthermore, in order to suppress the amount of heat generated by the relay coil, the upper limit of the power supply voltage applied to the coil must be lowered, and the voltage required to turn on the relay must be increased to maintain the on state, so the range of power that can be applied to the coil is Naturally, it is limited to a narrow range. This is a difficult condition for connecting to a car's power source, which has severe voltage fluctuations.

An object of the present invention is to provide a charging circuit that solves the above-mentioned problems by making the switch used for charging and discharging contactless.

According to the present invention, a battery unit in which a plurality of batteries are connected in series is divided into two parts, a first rechargeable battery unit divided part and a second rechargeable battery unit divided part, and a predetermined charge is applied to these two battery divided parts. At the same time as supplying a DC power source with a certain voltage to perform charging, a DC power source with a predetermined voltage is also supplied to an external circuit, and after charging is completed, the divided parts are connected in series and returned to the original rechargeable battery unit. A switching transistor inserted and connected between the first rechargeable battery unit divided portion and the second rechargeable battery unit divided portion;
A first transistor that turns on or off supply of charging current to the divided portion of the charging battery unit in response to a first or second control signal, and a comparison between the current flowing through this first transistor and a reference current when it is on. The first transistor operates as a constant current circuit, and after a certain period of time has elapsed during charging, the first transistor has a circuit that changes the output constant current value of the first transistor by changing the reference current value. A first control circuit connected to a connection point between the unit division part and the switching transistor and a charging current supply to the second rechargeable battery unit division part are turned on or off in response to the first or second control signal. the second transistor and when on this second
The second transistor is operated as a constant current circuit by comparing the current flowing through the transistor with a reference current, and after the certain period of charging has elapsed, the output constant current of the second transistor is changed by changing the reference current value. A second control circuit has a circuit for changing the value, and is connected to a connection point between the second rechargeable battery unit divided portion and the switching transistor, and a second control circuit that turns off the switching transistor when DC power is supplied. A first control signal that turns on the first and second transistors is output to form a parallel circuit of the divided parts of the first and second rechargeable battery units, and when there is no DC power supply, the switching transistor is turned on and the and an analog switch circuit that outputs a second control signal to turn off the first and second transistors and controls the first and second divided parts of the rechargeable battery unit to be connected in series to form a battery unit. A charging circuit is obtained.

Hereinafter, the present invention will be explained in more detail with reference to the drawings and the like. FIG. 2 is a circuit block diagram showing the basic configuration of the charging circuit according to the present invention. First rechargeable battery unit divided portion 11a of rechargeable battery unit 11
The emitter of the switching transistor 8 is connected to the negative terminal thereof, and the collector of the switching transistor 8 is connected to the positive terminal of the second rechargeable battery unit divided portion 11b. Further, a first control circuit 7 is connected between the negative electrode side of the first rechargeable battery unit divided portion 11a and the ground, and a second control circuit 9 is connected between the second rechargeable battery unit divided portion 11b and the line. When the transistors that are the components of the first and second control circuits 7 and 9 are turned on and the switching transistor 8 is turned off, the first and second rechargeable battery units 1 for charging are switched on.
A parallel circuit of 1a and 11b is formed. On the other hand, when the transistors of the first and second control circuits are turned off and the switching transistor 8 is turned on, a series circuit of the first and second rechargeable battery units 11a and 11b, that is, a rechargeable battery unit 11 having a terminal voltage for discharging is formed. be done. The analog switch circuit 12 has a CMOS analog switch 13 with low current consumption, and this analog switch 13 is supplied with power from the rechargeable battery unit side through terminals V and G, and is used as a power source such as a car battery for charging. It is incorporated as a control signal. This analog switch element 13 has control signal input terminals AC, BC and
When a predetermined voltage is applied to CC, A ₀ A ₁ respectively
conduction between B ₀ B ₁ and C ₀ C ₁ . Note that in this example, the predetermined voltage is applied to the terminal BC via the inverting circuit (transistor) 10. Therefore, when a power source such as a car battery is connected, the analog switch 13's AC,
A control signal is input to the terminals indicated by BC and CC, and A ₁ A ₀
and C ₁ C ₀ are connected, and B ₁ B ₀ is disconnected, so that the divided portions of the first and second rechargeable battery units are charged.

Note that the diode 6 is inserted for the purpose of preventing reverse current flow and preventing the analog switch circuit 12 from being operated by the rechargeable battery unit 11 itself.

Since the circuit of the present invention has all the switch parts contactless, even if it is subjected to mechanical shock or is used in an atmosphere of humidity, gas, etc., it will not only interrupt a call but also prevent damage to the contacts due to arc discharge. There is no room for such inconvenience to occur. In addition, the switching speed is fast, and the first transistor prevents damage to the battery due to current from the power supply when connected in series, so there is no need to insert a diode, and the power supply voltage range is wide, so it can be used even in car power supplies where voltage fluctuations are large. It is possible.

Furthermore, since no DC/DC converter is used, rapid charging is possible, and by controlling the base currents of the transistors in the first and second control circuits, a wide range of applications is possible. Furthermore, since each transistor is only for on/off control, its power consumption is low and a small size transistor can be used, so the device can be made smaller and the portability of the portable car phone can be increased.

If a charged battery is left undischarged, no current will flow because the rechargeable battery unit is only connected to the analog switch and the other transistors are completely off. The analog switch is a CMOS, and in the above state it is in a static state, with either the P-channel or N-channel transistor turned off, so there is no power supply current path, and the current consumption is negligibly small. Therefore, the rechargeable battery unit does not leak due to this circuit, and the only cause of a decrease in charging capacity is self-discharge of the battery itself.

Next, examples of the present invention will be described. FIG. 3 is a circuit block diagram showing one embodiment of the charging circuit according to the present invention. This embodiment basically adds a timer circuit 14 and a delay circuit 15 to the circuit shown in FIG.
It has a configuration with the addition of. Based on the control of the analog switch circuit, the first control circuit 7 charges the divided portion 11a of the rechargeable battery unit with a relatively large constant current for a certain period of time from the start of charging, and after a certain period of time has elapsed, with a small constant current. Let's do it. Second control circuit 9
The same applies to the rechargeable battery unit divided portion 11b. Here, analog switch element 13a ₁ , 1
3b ₁ and 13c are analog elements 13 in FIG.
corresponds to A control signal DLY is inputted via a delay circuit 15 to control signal input terminals AC and CC of analog switch elements 13a ₁ and 13b ₁ .
Further, 13a ₂ and 13b ₂ are switching elements that are controlled to be turned on or off in response to the output signal TM from the timer circuit 14. Furthermore, IC ₂ and IC ₃ compare a predetermined reference voltage generated inside the IC with the voltage applied to the terminal TH, and if the voltage applied to the terminal TH is lower than this reference voltage, the voltage is removed from the terminal OUT. It outputs a signal that turns on transistors Tr ₁ and Tr ₃ , respectively. Furthermore, IC ₂ and
V and G in IC ₃ are power supply terminals. Timer circuit 1
4 is for determining the quick charging time, and when the power is connected to the connector _Z1 , it is reset and starts counting, making the signal TM high level, thereby closing the contacts of the switching elements 13a ₂ and 13b ₂ .
RI ₁ and RI ₂ are resistances for detecting charging current, and the current value detected here is passed through operational amplifier IC ₅ to IC ₂ ,
It is compared with the reference voltage inside IC ₃ . operational amplifier
The gain of IC ₅ was originally analog switch element 13.
Since the contacts of a ₂ and 13b ₂ are closed, they are small, and the timer circuit counts a certain period of time and detects the low level.
At the time when the TM signal is generated, the analog switch elements 13a ₂ and 13b ₂ are opened by the TM signal, so that the signal becomes large.

In this embodiment _, instead of changing the reference voltage (current-voltage conversion is performed by RI ₁ and RI ₂ ), the transistor Tr ₁ , the constant current value of the constant current circuit of Tr ₃ is changed. Therefore, when the power source is connected, the constant current circuit has a large current value for quick charging, and after a certain period of time counted by the timer circuit 14 has passed, the current value becomes small for trickle charging.

Note that in this embodiment, the constant current value is changed by converting the reference current to a reference voltage and changing the handling detection voltage value, but relatively speaking, it is possible to change the constant current value by changing the reference current value. It is the same as doing.

Trickle charging is effective in making the respective capacities uniform when the charging capacities of the batteries are uneven, and can compensate for self-discharge of the rechargeable battery unit.

The delay circuit 15, which is made up of a CR, etc., is used to prevent oxidation of the pin contacts of connector _Z1 due to arcing caused by the charging current when _the power is connected. The signal DLY, which controls opening and closing of the analog switches 13a ₁ and 13b ₁ that operate the constant current circuit, is delayed so that the charging current flows.

When charging is completed and the power is removed, the inverting circuit (transistor) 10 is turned off and the INV signal becomes high level, so the analog switch element 13c closes.
The switching transistor 8 is turned on. Also,
DLY becomes a low level because the charge in the capacitor C of the delay circuit 15 is quickly discharged through the diode Dr ₂ . Therefore, the transistor Tr ₁ ,
Since Tr ₃ is off and the switching transistor 8 is on, the first and second rechargeable battery units 11
a and 11b form a series circuit, and can be discharged at a predetermined voltage. Note that the resistor R _p of the delay circuit 15 is inserted to fix the input voltage since the input impedance of the analog switch is high.

Since this embodiment uses constant current circuits for the first and second control circuits, charging can be performed without malfunctioning even if the terminal voltage of the rechargeable battery unit changes in an environment with severe temperature changes. Furthermore, the delay circuit does not damage the power supply connector, and the timer circuit allows safe rapid charging and equalization of battery capacity.

As a modification of this embodiment, the terminal voltage of the rechargeable battery is detected instead of the constant current circuit, and the transistors Tr ₁ ,
Jogging charging can also be performed by turning Tr ₃ on and off.

As described in detail above, according to the present invention, a changeover switch can be made contactless, thereby solving all the drawbacks of conventional circuits, and making it possible to downsize portable car phones and the like. In addition, stable charging can be performed without causing noise or the like to the mobile device itself connected to the outside.

[Brief explanation of drawings]

Fig. 1 is a circuit block diagram showing an example of a conventional charging circuit that divides and charges a battery using a relay in order to perform rapid charging from an automobile battery, and Fig. 2 shows the basic configuration of a charging circuit according to the present invention. FIG. 3 is a circuit block diagram showing an embodiment of the charging circuit according to the present invention. 1, 2, 6... Diode, 3, 4... Transfer contact, 5... Coil, 7... First control circuit, 8, 10... Transistor, 9... Second control circuit, 11... Charging battery unit, 11a...first rechargeable battery unit divided portion, 11b...second rechargeable battery unit divided portion, 12...analog switch circuit, 13...CMOS analog switch,
13a ₁ , 13b ₁ , 13c...analog switch element, 14...timer circuit, 15...delay circuit,
Dr ₂ ... Diode, IC ₂ , IC ₃ ... IC with internal reference voltage and comparator, IC ₅ ... Operational amplifier,
C...Capacitor, R...Resistor.

Claims (1)

[Claims] 1. A battery unit in which a plurality of batteries are connected in series is divided into two parts, a first rechargeable battery unit divided part and a second rechargeable battery unit divided part, and When charging is performed by supplying DC power from the on-board battery, the DC power is also supplied to the main body of the on-board radio, and when there is no DC power supply from the on-board battery, the divided parts are connected in series to restore the original rechargeable battery. In the vehicle-mounted radio charging circuit that returns to the unit, the first rechargeable battery unit divided portion and the second
The rechargeable battery unit is inserted and connected between the divided parts,
a series-parallel connection switching transistor for battery units that is turned off in response to a first control signal and turned on in response to a second control signal; a first transistor that is turned on or off in response to a second control signal; when on, the first transistor operates as a constant current circuit by comparing the current flowing through the first transistor with a reference current; and The first transistor has a circuit that changes an output constant current value of the first transistor by changing a reference current value in response to a current control signal indicating that a certain period of time has elapsed during charging.
a first control circuit connected between a point where the divided portion of the rechargeable battery unit and the series-parallel connection switching transistor are connected and a first input terminal to which the first terminal of the DC power source is connected; , a second transistor that turns on or off a charging current to the second rechargeable battery unit divided portion in response to the first or second control signal, and a current flowing through the second transistor when turned on and a reference current; The second transistor is operated as a constant current circuit by comparison with the reference current value, and the output of the second transistor is controlled by changing the reference current value in response to the current control signal indicating the elapse of the certain period of charging. a second input terminal that has a circuit for changing a current value and connects a point where the second rechargeable battery unit divided portion and the series/parallel connection switching transistor are connected and a second terminal of the DC power source; a second control circuit connected between the DC power source and the DC power source in response to a first state in which first and second terminals of the DC power source are connected to the first and second input terminals, respectively; outputting a first control signal that turns off the series/parallel connection switching transistor and turns on the first and second transistors after a predetermined time delay to form a parallel circuit of the divided portions of the first and second rechargeable battery units; , outputting a second control signal that turns on the series-parallel connection switching transistor and turns off the first and second transistors in a state other than the first state, and divides the first and second rechargeable battery units. and a third control circuit that controls the batteries to be connected in series to form a battery unit.