JPH08182203A - Battery charge control circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] Out of the batteries that make up the assembled battery, the surplus charging power supplied to the already fully charged batteries is extracted to the outside for reuse. [Structure] When charging is started using the AC charger 101, a single cell of the assembled battery 1 having a small charge capacity or a high charging efficiency is fully charged first, and then fully charged. An overcharge detection signal is output from the overcharge detection circuit 103 corresponding to the single cell. Then, the AND circuit 106 inside the DC-DC converter 104 outputs a pulse signal in synchronization with the output of the oscillation circuit 105, and the power transistor also repeats on / off in synchronization with the output of the oscillation circuit. As a result, an alternating current is generated on the secondary side of the insulating transformer 108, and this current is converted into a direct current by the rectifier circuit 109 and supplied to each unit cell. In this way, the surplus charging power can be used to charge the uncharged single cell, and the bypass circuit need not be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembled battery charge control circuit for controlling charging of an assembled battery composed of a plurality of rechargeable batteries connected in series.

[0002]

2. Description of the Related Art An electric vehicle drives a motor by using electric power of a battery and travels by a driving force of the motor. It requires a fairly high voltage to drive the motor,
2. Description of the Related Art There is known an electric vehicle including an assembled battery charging control circuit that controls charging of the assembled battery by using an assembled battery in which a large number of batteries are connected in series as a battery.

FIG. 6 is a block diagram of a battery pack charge control circuit of this type. In FIG. 6, 11 to 1n are battery groups that form the assembled battery 1, and a plurality of rechargeable batteries are connected in series. Below, each battery which comprises the assembled battery 1 is called a single cell. Reference numeral 2 is a charger for charging the assembled battery 1. A contact 3 of a relay is provided between the charger 2 and the assembled battery 1, and when the contact 3 is closed, a charging current from the charger 2 is supplied to the assembled battery 1 to charge each single cell.
Reference numeral 4 is an overvoltage detection circuit for detecting that the terminal voltage of a single cell exceeds a specified voltage and becomes an overvoltage, and is provided for each single cell. Reference numeral 5 denotes a bypass circuit for bypassing the charging current so that the charging current does not flow in the unit cell when the overvoltage detection circuit 4 detects that the unit cell is overvoltage, and is also provided for each unit cell. There is. 6
Is an inverter that converts the voltage of the entire assembled battery into an AC voltage. The AC voltage from this inverter causes the motor 7
Is driven.

FIG. 7 is a circuit diagram showing the internal structure of the overvoltage detection circuit 4 shown in FIG. 6, in which a reference voltage generating circuit 8 including a resistor R1 and a Zener diode D1 and a resistor R2.
A voltage detection circuit 9 composed of R3 and a comparator OP1
And resistors R4 and R5 for adjusting the output level of the comparator OP1. On the other hand, FIG. 8 is a circuit diagram showing an internal configuration of the bypass circuit 5 shown in FIG.
P2, a transistor TR1, a current detection resistor R6,
It consists of feedback resistors R7 and R8.

In the conventional battery pack charging control circuit thus configured, when the contact 3 of the relay is closed, the current from the charger 2 is supplied to the battery pack 1 and the charging of each single cell 11 to 1n is started. To be done. When some single cells are fully charged,
The output of the comparator OP1 inside the overvoltage detection circuit 4 corresponding to the fully charged single cell changes from the low level to the high level, whereby the output of the operational amplifier OP2 inside the bypass circuit 5 is inverted and the transistor TR1 is inverted.
Is turned on, and the charging current from the charger 2 does not flow in the single cell but flows in the transistor TR1. The above operation prevents overcharge of the single cell.

[0006]

In the conventional battery pack charge control circuit shown in FIG. 6, charging is continuously performed until all the unit cells forming the battery pack are fully charged. However, since the charging capacity, the charging efficiency, and the like vary depending on the single cell, the time from the start of charging to the full charge differs depending on each single cell. Therefore, when only some of the unit cells are not fully charged, the charging current flowing in the other unit cells flows into each bypass circuit, wasting energy. Further, as a result of supplying a large amount of current to the bypass circuit, the bypass circuit may generate heat and the life of the bypass circuit may be shortened. Although it is possible to suppress the heat generation of the bypass circuit by providing a fan, a heat dissipation member, etc., the overall size of the device becomes large and the cost becomes high.

An object of the present invention is to take out the excess charging power supplied to the already fully charged battery among the batteries constituting the assembled battery to the outside and reuse it, so that the assembled battery can be assembled without providing a bypass circuit. An object of the present invention is to provide an assembled battery charge control circuit that charges a battery.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG. 1 showing an embodiment. The present invention is directed to an assembled battery 1 constructed by connecting a plurality of rechargeable batteries in series and an assembled battery. An overvoltage detection circuit 103, which is provided for each battery constituting the battery 1 and outputs an overvoltage detection signal when the terminal voltage of the battery becomes equal to or higher than a predetermined voltage during charging, prevents overcharge of each battery constituting the assembled battery 1. It is applied to the assembled battery charging control circuit and is provided for each overvoltage detection circuit 103. When an overvoltage detection signal is output from the overvoltage detection circuit 103, power is supplied using the terminal voltage of the battery corresponding to the overvoltage detection circuit 103 as an input voltage. The above object is achieved by including the insulation type DC-DC converter 104 that performs conversion and takes out the converted power to the outside. According to a second aspect of the present invention, in the battery pack charge control circuit according to the first aspect, the output terminals of the DC-DC converters 104 are connected in parallel to each other, and the DC-DC converters 104 are connected.
Performs power conversion so that its output voltage becomes higher than the voltage of the entire assembled battery, and the power converted by each DC-DC converter 104 is supplied to the assembled battery 1 together with the charging power from the charger. DC-DC converter 10
4 is connected to the charger and the battery pack 1. The invention according to claim 3 is provided for each assembled battery 1 configured by connecting a plurality of rechargeable batteries in series, and each battery constituting the assembled battery 1, and the terminal voltage of the battery is a predetermined voltage at the time of charging. A plurality of batteries arranged adjacent to each other, which are applied to a battery pack charging control circuit that includes an overvoltage detection circuit 103 that outputs an overvoltage detection signal and that prevents overcharge of each battery included in the battery pack 1 Is provided as a unit, and when an overvoltage detection signal is output from the overvoltage detection circuit 103 included in the unit, power conversion is performed using the terminal voltage of the battery included in the unit as an input voltage, and the converted power is externally supplied. It is provided with an insulation type DC-DC converter 104 which is taken out to the above. According to a fourth aspect of the present invention, in the battery pack charge control circuit according to the third aspect, the overvoltage detection signals output from the respective overvoltage detection circuits 103 are electrically insulated from each other in the DC-DC converter. 1
The DC-DC converter 104 is configured to perform power conversion based on the logical sum of the isolated overvoltage detection signals that are input to 04.

[0009]

According to the first aspect of the invention, the DC-DC converter 104 is used to perform power conversion using the terminal voltage of the battery in the overvoltage state as an input voltage, and the converted power is extracted to the outside. In the invention according to claim 2, power conversion is performed so that the output voltage of the DC-DC converter 104 becomes higher than the voltage of the entire assembled battery, and the DC-DC converter 1
The power converted by 04 is supplied to the assembled battery 1 together with the charging power from the charger. In the invention according to claim 3, when a plurality of batteries arranged adjacently are used as a unit and an overvoltage detection signal is output from any of the overvoltage detection circuits 103 included in each unit, each unit Power conversion is performed using the DC-DC converter 104 with the terminal voltage of the battery included in the input voltage as the input voltage, and the converted power is extracted to the outside. In the invention according to claim 4, the overvoltage detection signals output from the respective overvoltage detection circuits 103 are input to the DC-DC converter 104 in a state of being electrically insulated from each other, and the overvoltage detection signals are ORed. Based on the power conversion.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for the purpose of making the present invention easy to understand. It is not limited to.

[0011]

【Example】

-First Embodiment- Fig. 1 is a block diagram of a first embodiment of an assembled battery charging control circuit according to the present invention. In FIG. 1, 101 is an AC charger for outputting AC voltage, such as a household outlet, 102
Is a rectifier circuit that converts AC voltage to DC voltage, and AC
A contact SW1 of a relay (not shown) is connected between the charger 101 and the rectifier circuit 102. 103 is an overvoltage detection circuit having the same configuration as the overvoltage detection circuit 4 of FIG.
4 is a DC-DC that takes out excess charging power of a single cell to the outside.
The converter is also provided for each single cell 11 to 1n, and the output terminals of each DC-DC converter 104 are connected in parallel with the rectifier circuit 102 and the load M.

FIG. 2 is a circuit diagram showing the internal structure of the DC-DC converter 104. In FIG. 2, 105 is an oscillation circuit that outputs a square wave of a predetermined frequency, 106 is an AND circuit that calculates the logical product of the output of the oscillation circuit 105 and the output of the overvoltage detection circuit 104, and Tr2 is the output of the AND circuit 106 is high. It is a power transistor that turns on when it reaches a level, and a snubber circuit 107 for protecting the power transistor Tr2 is connected between the emitter and collector of the power transistor Tr2. Reference numeral 108 denotes an isolation transformer, which has a diode D1 and a capacitor C1 on its secondary side.
Is connected to the rectifier circuit 109.

The operation of the first embodiment will be described below with reference to FIGS. When charging is started using the AC charger 101, among the single cells that form the assembled battery 1, those having a small charge capacity and good charging efficiency are first fully charged, and then the fully charged single cells. Overcharge detection circuit 1 corresponding to
An overcharge detection signal is output from 03. And DC-
The AND circuit 106 inside the DC converter 104 outputs a pulse signal in synchronization with the output of the oscillation circuit 105, and the power transistor also repeats on / off in synchronization with the output of the oscillation circuit. As a result, an alternating current is generated on the secondary side of the insulating transformer 108, and this current is converted into a direct current by the rectifier circuit 109.

The output terminals of the DC-DC converters 104 are connected in parallel, and the battery pack 1 and the rectifying circuit 102 are also connected in parallel.
The direct current rectified in 09 is supplied to each of the unit cells 11 to 1n together with the charging current flowing from the AC charger 101 through the rectifier circuit 102.

By adjusting the number of windings of the insulation transformer, the induced electromotive force generated on the secondary side of the insulation transformer can be made higher than the voltage of the entire assembled battery, and thus the insulation transformer It is possible to reliably return the current generated on the secondary side to the assembled battery.

As described above, in the first embodiment, the battery pack 1
For the single cell that has been fully charged first among the single cells configuring the above, the surplus charging power is supplied to the DC-DC converter 108.
Since it is converted into a direct current and used for charging other uncharged single cells, the surplus charging power can be effectively used. Further, since it is not necessary to provide a bypass circuit as in the conventional case, there is no problem of shortening the life due to heat generation of the bypass circuit. Since the DC-DC converter 108 has better conversion efficiency than the bypass circuit,
There is no danger of heat generation and there is no need to provide a fan or the like, which can reduce costs and downsize the device.

-Second Embodiment- In the second embodiment, a plurality of single cells constituting a battery pack are grouped and a DC-DC converter is provided for each group. FIG. 3 is a block diagram of the second embodiment.
The same components as those in the block diagram of the embodiment are denoted by the same reference numerals, and the differences will be mainly described below. FIG.
As shown in FIG. 3, the single cells that form the assembled battery 1 are divided into groups of three, and one DC-DC converter 104A is provided for each group.

FIG. 4 is a circuit diagram showing the internal structure of the DC-DC converter 104A of the second embodiment. The DC-DC converter 104A of the second embodiment differs from that of the first embodiment in that it has a photocoupler 110 inside.
As shown in FIG. 4, the output of the overvoltage detection circuit 103 is connected to each LED inside the photocoupler 110, and the collector terminal of the phototransistor inside the photocoupler 110 is connected to the input terminal of the AND circuit 106. Since other configurations are common to those of the first embodiment, description thereof will be omitted.

The operation of the second embodiment will be described below with reference to FIGS. When charging is started by using the AC charger 101, some of the single cells in each set eventually become fully charged, and the overcharge detection circuit 103 corresponding to the single cell outputs an overcharge detection signal. As a result, the LED inside the photocoupler 110 corresponding to the unit cell is turned on and the phototransistor is turned on, and the AND circuit 106 outputs a pulse signal synchronized with the output of the oscillation circuit 105. The power transistor Tr2 is repeatedly turned on and off in response to the pulse signal output from the AND circuit 106, an alternating current is generated on the secondary side of the insulating transformer 108, and this current is converted into a direct current, and then each single cell is converted. Is supplied to.

As described above, in the second embodiment, a plurality of single cells are set as a group, and the DC-DC converter 104A is set for each group.
The total number of the DC-DC converters 104A can be made smaller than that in the first embodiment, and the cost can be reduced. In addition, since the overvoltage detection signal output from the overvoltage detection circuit 103 is electrically insulated from each other by using the photocoupler 110, a logical sum of a plurality of overvoltage detection signals can be calculated without causing a short circuit or the like. As in the example, overcharging of each single cell can be reliably prevented.

-Third Embodiment- In the third embodiment, the direct current converted by the DC-DC converter is used for charging the auxiliary battery. Figure 5
Is a block diagram of the third embodiment, and the same reference numerals are given to the same components as those in the block diagram of the first embodiment, and the differences will be mainly described below.

In FIG. 5, 111 is a DC-D for changing the voltage level of the DC voltage output from the rectifier circuit 102.
The auxiliary battery 112 is connected to the output terminal of the DC-DC converter 111, which is a C converter. In this way, the auxiliary battery 112 is charged via the DC-DC converter 111. 113 is an auxiliary battery 112
Is a load driven by. In the signal line connecting the DC-DC converter 111 and the auxiliary battery 112,
The output terminal of each DC-DC converter 104 is connected. The DC-DC converter 104 has the same configuration as that of the first or second embodiment.

The operation of the third embodiment will be described below with reference to FIG. When one of the unit cells forming the assembled battery 1 is fully charged, the DC-DC converter 104 converts the surplus charging power into a DC current, and the DC-DC converter 111.
Is supplied to the auxiliary battery 112 via. This allows
The auxiliary battery 112 is charged.

Although no particular consideration is given to the case where the auxiliary battery 112 is overcharged in FIG. 5, an overvoltage detection circuit or a bypass circuit may be connected to the auxiliary battery 112.

[0025]

As described in detail above, according to the present invention, when an overvoltage detection signal is output, power conversion is performed using a DC-DC converter with the terminal voltage of a battery as an input voltage, and the converted power is converted. Since the battery is taken out to the outside, the surplus charging power can be used for other purposes without wasting. Further, since it is not necessary to provide a bypass circuit, there is no problem of heat generation in the bypass circuit. According to the invention described in claim 2, since the power conversion is performed so that the output voltage of the DC-DC converter becomes higher than the voltage of the entire assembled battery, the output voltage of the DC-DC converter is charged in the assembled battery. Can be reused. According to the invention of claim 3, the DC is set in units of a plurality of batteries arranged adjacent to each other.
-DC-DC because a DC converter is provided
It is possible to reuse the surplus charging power while reducing the number of converters. According to the invention described in claim 4, since the overvoltage detection signals output from the respective overvoltage detection circuits are electrically insulated from each other, a short circuit or the like occurs even if the DC level of each overvoltage detection circuit is different. You can safely operate logical OR without Therefore, if any of the overvoltage detection circuits outputs an overvoltage detection signal, D
The C-DC converter can be activated immediately.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of an assembled battery charging control circuit according to the present invention.

FIG. 2 is a circuit diagram showing an internal configuration of the DC-DC converter of the first embodiment.

FIG. 3 is a block diagram of a second embodiment of an assembled battery charging control circuit according to the present invention.

FIG. 4 is a circuit diagram showing an internal configuration of a DC-DC converter according to a second embodiment.

FIG. 5 is a block diagram of a third embodiment of an assembled battery charging control circuit according to the present invention.

FIG. 6 is a block diagram of a conventional battery pack charge control circuit.

7 is a circuit diagram of the overvoltage detection circuit shown in FIG.

FIG. 8 is a circuit diagram of the bypass circuit shown in FIG.

[Explanation of symbols]

 1 assembled battery 2 charger 3 relay contact 4,104 overvoltage detection circuit 5 bypass circuit 6 inverter circuit 7 motor 101 AC charger 102 rectifier circuit 103 overvoltage detection circuit 104, 104A DC-DC converter 105 oscillation circuit

Claims (4)

[Claims] 1. An assembled battery configured by connecting a plurality of rechargeable batteries in series, and provided for each of the batteries forming the assembled battery, when the terminal voltage of the battery becomes a predetermined voltage or more during charging. An overvoltage detection circuit that outputs an overvoltage detection signal, and an assembled battery charging control circuit that prevents overcharge of each of the batteries that form the assembled battery, is provided for each of the overvoltage detection circuits, and the overvoltage detection circuit When an overvoltage detection signal is output, the terminal voltage of the battery corresponding to the overvoltage detection circuit is used as an input voltage for power conversion, and an insulated DC-DC converter for extracting the converted power to the outside is provided. Characterized battery pack charge control circuit. 2. The assembled battery charging control circuit according to claim 1, wherein the output terminals of the respective DC-DC converters are connected in parallel with each other, and the output voltage of each of the DC-DC converters is the assembled group. The power of the DC-DC converter is converted so that the voltage is higher than the voltage of the entire battery, and the power converted by the DC-DC converters is supplied to the battery pack together with the charging power from the charger. A battery pack charge control circuit, wherein terminals are connected to the charger and the battery pack. 3. An assembled battery configured by connecting a plurality of rechargeable batteries in series, and provided for each of the batteries constituting the assembled battery, when the terminal voltage of the battery becomes equal to or higher than a predetermined voltage during charging. In an assembled battery charging control circuit, which includes an overvoltage detection circuit that outputs an overvoltage detection signal, and that prevents overcharge of each of the batteries that form the assembled battery, a plurality of adjacent batteries are provided as a unit. When the overvoltage detection signal is output from the overvoltage detection circuit included in the unit, power conversion is performed using the terminal voltage of the battery included in the unit as an input voltage, and the converted power is output to the outside. An assembled battery charging control circuit comprising an isolated DC-DC converter for taking out. 4. The assembled battery charging control circuit according to claim 3, wherein the overvoltage detection signals output from the overvoltage detection circuits are electrically isolated from each other by the DC voltage.
-The DC-DC converter is input to the DC converter, and the DC-DC converter performs the power conversion based on the logical sum of the insulated overvoltage detection signals.