JPH08186940A - Charge control circuit for combined battery - Google Patents

Abstract

(57) [Abstract] [Purpose] An overvoltage detection circuit that detects whether or not each battery that constitutes an assembled battery is in an overvoltage state has a hysteresis characteristic. [Constitution] When the terminal voltage of any of the batteries constituting the assembled battery 1 exceeds the first voltage, the overvoltage detection circuit 104 outputs an overvoltage detection signal, and all the charging current supplied to the battery is bypassed by the bypass circuit 105. Flow to. Then, when the terminal voltage of the battery falls below the second voltage which is lower than the first voltage, the overvoltage detection circuit 104 stops outputting the overvoltage detection signal, and the battery is recharged. Further, the overvoltage detection signals output from the respective overvoltage detection circuits 104 are logically ORed in a state of being electrically insulated from each other, and based on the result, the measurement circuit 111 determines the number of times the overvoltage detection signal is output. measure. Then, the constant current charging circuit 103 changes the amount of charging current supplied to each battery according to the number of times to prevent overcharging of each battery.

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 formed by connecting a plurality of rechargeable batteries 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 turned on.
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 provide a terminal voltage of each battery in an overvoltage state by providing an overvoltage detection circuit for detecting whether or not each battery constituting the assembled battery is in an overvoltage state with a hysteresis characteristic. An object of the present invention is to provide an assembled battery charge control circuit that is surely lowered.

[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 104, 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. When the terminal voltage of the battery exceeds a first voltage, an overvoltage detection signal is output, and when the terminal voltage falls below a second voltage lower than the first voltage, the overvoltage is applied. The above object is achieved by configuring the overvoltage detection circuit 104 so as to stop the output of the detection signal. The invention according to claim 2 is
In the battery pack charge control circuit according to claim 1, a measuring unit 111 that measures the number of times an overvoltage detection signal is output from any of the overvoltage detection circuits 104; and a measuring unit 1.
As the number of times measured by 11 increases, the charging current control means 103 that reduces the charging current supplied to the batteries forming the assembled battery 1 is provided. According to a third aspect of the present invention, in the battery pack charge control circuit according to the first aspect, the insulating means 1 electrically insulates the overvoltage detection signals output from the overvoltage detection circuits 104 from each other.
09 and an OR circuit 110 for calculating the logical sum of the overvoltage detection signals insulated by the insulating means 109, and the measuring means 111 is configured to measure the number of times in accordance with the output change of the OR circuit 110. Is. According to a fourth aspect of the present invention, in the assembled battery charge control circuit according to the first aspect, the total voltage detection circuit 113 that measures the voltage of the entire assembled battery and the voltage measured by the total voltage detection circuit 113 are high. The charging current control means 103 for reducing the charging current supplied to the batteries constituting the assembled battery 1 is provided.

[0009]

According to the invention described in claim 1, when the terminal voltage of each battery constituting the assembled battery 1 exceeds the first voltage, an overvoltage detection signal is output, and thereafter the terminal voltage is lower than the first voltage. When it falls below the second voltage, the output of the overvoltage detection signal is stopped. In the invention according to claim 2, the overvoltage detection circuit 10 is provided.
The number of times the overvoltage detection signal is output from any one of 4 is measured, and the charging current supplied to each battery is reduced as the number of times increases. According to the third aspect of the present invention, the overvoltage detection signals output from the respective overvoltage detection circuits 104 are electrically insulated, the logical sum of the insulated overvoltage detection signals is calculated, and the level change of the logical sum is performed. And the number of times the overvoltage detection signal is output is measured. In the invention according to claim 4, the higher the voltage of the whole assembled battery, the smaller the charging current supplied to each battery constituting the assembled battery 1.

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 circuit diagram of a first embodiment of an assembled battery charging control circuit according to the present invention. In FIG. 1, the same components as those in FIG. 6 are denoted by the same reference numerals, and the differences will be mainly described below. In FIG. 1, 101 is an AC charger that outputs an AC voltage from a household outlet, 102 is a rectifier circuit that converts the AC voltage into a DC voltage, and a relay is provided between the AC charger 101 and the rectifier circuit 102. Contact SW (not shown)
1 is connected. Reference numeral 103 is a constant current charging circuit that adjusts the amount of charging current supplied to the assembled battery 1, and 104 is an overvoltage detection circuit that detects that the terminal voltage of a single cell exceeds a specified voltage and becomes an overvoltage. It is provided every 11 to 1n. Reference numeral 105 denotes a bypass circuit that bypasses the charging current from the AC charger 101 when the overvoltage detection signal is output from the overvoltage detection circuit 104.

FIG. 2 is a circuit diagram showing the internal configuration of the overvoltage detection circuit 104 and the bypass circuit 105. Reference numeral 106 denotes a voltage detection circuit for detecting the terminal voltage of the single cell, 107 outputs an overvoltage detection signal when the terminal voltage of the single cell becomes equal to or higher than the first voltage V1, and thereafter, the first terminal voltage whose terminal voltage is lower than the first voltage V1. It is a hysteresis circuit that continuously outputs the overvoltage detection signal while the voltage V2 is 2 or more. Reference numeral 108 denotes a constant current control circuit that outputs a high level signal when the hysteresis circuit 107 outputs an overvoltage detection signal. Tr
A transistor 2 is turned on when a high level signal is output from the constant current control circuit 108. Transistor T
When r2 is turned on, a current flows between the collector and the emitter, a predetermined voltage is applied across the resistor R9, and the voltage at point a in the figure rises. The point a side of the resistor is the constant current control circuit 10
8 is connected to the constant current control circuit 108.
Detects the amount of current flowing through the transistor Tr2.

Returning to FIG. 1, 109 is an overvoltage detection circuit 1.
This is an isolator that electrically insulates each of the overvoltage detection signals output from 04. The isolator 109 is provided to prevent a short circuit or the like from occurring because the direct current levels of the overvoltage detection circuit 104 are different. Reference numeral 110 is an OR circuit that calculates the logical sum of the outputs of the respective isolators 139. The OR circuit 110 outputs a high level signal when any of the overvoltage detection circuits 104 outputs an overvoltage detection signal. 111 is an OR circuit 1
It is a measuring circuit that measures the number of times the output of 10 changes from a low level to a high level. Reference numeral 112 denotes a D / A conversion circuit that converts the measurement value of the measurement circuit 111 into an analog value, and the converted analog value is input to the constant current charging circuit 103.

FIG. 3 is a diagram showing the time-dependent changes in the terminal voltages of the unit cells P, Q, and R. The change in the unit cell P is shown by a solid line, the change in the unit cell Q is shown by a chain line, and the change in the unit cell R is shown. The change is indicated by a chain double-dashed line. The operation of the first embodiment will be described below with reference to FIGS. When charging is started, at time t1, the terminal voltage of the unit cell P exceeds the voltage V1 which is the overcharge voltage level. As a result, the overvoltage detection signal is output from the hysteresis circuit 107 of the single cell P, and the constant current control circuit 108 of the single cell P outputs a high level signal in response thereto. As a result, the transistor Tr2 inside the bypass circuit 105 is turned on, and the current i that should flow in the single cell is
1 flows through between the collector and the emitter of the transistor Tr2. Hereinafter, the current flowing between the collector and the emitter of the transistor Tr2 will be referred to as the bypass current i3.

When the maximum value of the bypass current i3 that can flow between the collector and the emitter when the transistor Tr2 is on is made larger than the charging current i1 for the single cell P, the current i2 also flows from the single cell P as shown in FIG. Transistor Tr2
Flows between the emitter and collector of. As a result, the terminal voltage of the unit cell P rapidly decreases. However, if the terminal voltage of the unit cell P is equal to or higher than the second voltage V2 that is lower than the first voltage V1 (time t1 to t2 in FIG. 3), the overvoltage detection signal is continuously output from the hysteresis circuit 107 of the unit cell P. Is output.

As shown in FIGS. 1 and 2, the overvoltage detection signal output from the hysteresis circuit 107 is the isolator 1
After being electrically insulated by 09, it is input to the OR circuit 110. When one of the hysteresis circuits 107 outputs the overvoltage detection signal, the output of the OR circuit 110 changes from the low level to the high level, and the measurement circuit 1
11 counts up the measured value by 1. In this way, the measurement circuit 111 measures the number of times that the terminal voltage of any single cell exceeds the overvoltage detection level V1.

At time t2, the terminal voltage of the unit cell P falls below the voltage V2, and the hysteresis circuit 107 does not output the overvoltage detection signal. As a result, the bypass circuit 105 of the single cell P stops operating, and the single cell P is charged again (time t2 to t4 in FIG. 3).

At time t3, the terminal voltage of the single cell Q exceeds the voltage V1 this time, and the hysteresis circuit 107 of the single cell Q outputs the overvoltage detection signal. Then, the bypass circuit 105 of the single cell Q starts operating, and a current flows from the single cell Q to the transistor Tr2 inside the bypass circuit 105, so that the voltage of the single cell Q decreases. Further, the measurement value of the measurement circuit 111 changes to 2 because the hysteresis circuit 107 of the single cell Q outputs the overvoltage detection signal.

The measured value of the measuring circuit 111 is input to the constant current charging circuit 103, and the constant current charging circuit 103 supplies a smaller current than the initial value to each of the unit cells 11 to 1n. As a result, overcharge of each single cell 11 to 1n is prevented. In this way, the constant current charging circuit 103 changes the amount of charging current flowing through the assembled battery 1 according to the value measured by the measuring circuit 111,
The larger the measured value, the smaller the charging current amount.

At time t4, the terminal voltage of the unit cell P again exceeds the voltage V1 which is the overvoltage detection level, and the bypass circuit 105 of the unit cell P starts operating again. At the same time, the measurement value of the measurement circuit 111 changes to 3, and the constant current charging circuit 103 supplies a smaller amount of charging current than before to each of the unit cells 11 to 1n.

At time t5, the terminal voltage of the unit cell Q falls below the voltage V1, the bypass circuit 105 of the unit cell Q stops operating, and the unit cell Q is charged again. After that, time t6
Then, the terminal voltage of the single cell R exceeds the voltage V1 that is the overvoltage detection level, the bypass circuit 105 of the single cell R starts operating, and the measurement value of the measurement circuit 111 changes to 4. As a result, the constant current charging circuit 103 supplies a smaller amount of current to each unit cell.

As described above, according to the first embodiment, since the overvoltage detection circuit 104 is provided with the hysteresis characteristic, the terminal voltage of the overcharged single cell can be surely lowered. Further, since a current equal to or higher than the charging current flowing in the single cell can be made to flow in the bypass circuit 105, a current can also be made to flow from the single cell side in the bypass circuit, and the overcharged terminal voltage can be promptly lowered. Furthermore, even if the single cell is fully charged,
When the terminal voltage of the unit cell drops, the bypass circuit 105
Since the bypass of the charging current is stopped and the charging is performed again, the bypass circuit 105 operates only intermittently, and the bypass circuit 105 does not generate heat.
Furthermore, the number of times the battery is fully charged is measured, and the charging current flowing through each single cell is reduced as the number of times increases, so it is possible to charge each single cell at high speed while preventing overcharging of each single cell. it can.

Second Embodiment In a second embodiment described below, the amount of charging current supplied to each single cell is controlled according to the voltage of the entire assembled battery. FIG. 4 is a block diagram of the second embodiment, in which components common to those of the first embodiment are designated by the same reference numerals,
The difference will be mainly described below. The overvoltage detection circuit 104 and the bypass circuit 105 of the second embodiment have the same configurations as those of the first embodiment. Reference numeral 113 shown in FIG. 4 is a voltage detection circuit that measures the voltage of the entire assembled battery and adjusts the amount of current supplied from the constant current charging circuit 103 to each of the unit cells 11 to 1n according to the measured voltage value.

FIG. 5 is a diagram showing changes in the charging current instruction value that the voltage detection circuit 113 instructs the constant current charging circuit 103. The horizontal axis represents the voltage of the entire battery pack and the vertical axis represents the charging current instruction value. Show. As shown in the figure, when the voltage of the entire assembled battery is low, the charging current instruction value does not change, and the charging current instruction value linearly decreases from the time when the voltage exceeds the predetermined value VL.

The operation of the second embodiment will be described below with reference to FIGS. At the beginning of charging, a sufficient amount of charging current is supplied from the constant current charging circuit 103 to each unit cell, and the voltage of the entire assembled battery gradually increases. When the voltage of the entire assembled battery exceeds the predetermined value VL, the voltage detection circuit 113 instructs the constant current charging circuit 103 to gradually reduce the charging current. As a result, the charging current supplied from the constant current charging circuit 103 gradually decreases, and overcharge of each single cell is prevented.

As described above, in the second embodiment, the same effect as that of the first embodiment can be obtained with a simpler structure than that of the first embodiment.

In FIG. 5, the charging current instruction value is linearly decreased when the voltage of the whole assembled battery exceeds a predetermined value, but the method of decreasing the charging current instruction value is not limited to that of FIG. May be reduced.

In the embodiment thus constructed, the measuring circuit 111 serves as measuring means, the isolator 109 serves as insulating means, the voltage detecting circuit 113 serves as a total voltage detecting circuit, and the constant current charging circuit 103 serves as charging current control. It corresponds to each means.

[0029]

As described above in detail, according to the present invention, when the terminal voltage of the battery exceeds the first voltage, the overvoltage is detected, and then the second voltage lower than the first voltage is detected. Since the output of the overvoltage detection signal is stopped when the voltage falls below the threshold voltage, the terminal voltage of each battery can be reliably reduced. According to the second aspect of the present invention, the charging current supplied to each battery is reduced as the number of times the overvoltage detection signal is output increases, so that overcharging of all batteries can be effectively prevented. According to the invention as set forth in claim 3, the overvoltage detection signals are insulated from each other to calculate a logical sum, and the number of times the overvoltage detection signal is output is measured based on the calculation result of the logical sum. Even if there is a difference in the DC level of the circuit, the logical sum can be calculated without causing a short circuit. According to the invention of claim 4, the higher the voltage of the entire assembled battery, the smaller the charging current supplied to the batteries constituting the assembled battery. Therefore, overcharging of each battery can be reliably prevented.

[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 block diagram showing the internal configurations of an overvoltage detection circuit and a bypass circuit.

FIG. 3 is a diagram showing temporal changes in terminal voltages of single cells P, Q, and R.

FIG. 4 is a block diagram of a second embodiment of an assembled battery charging control circuit according to the present invention.

FIG. 5 is a diagram showing a relationship between the voltage of the entire assembled battery and a charging current instruction value.

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

7 is a circuit diagram showing an internal configuration of the overvoltage detection circuit shown in FIG.

FIG. 8 is a circuit diagram showing an internal configuration of a bypass circuit shown in FIG.

[Explanation of symbols]

 1 Battery pack 2 Charger 3 Relay contact 4,104 Overvoltage detection circuit 5,105 Bypass circuit 6 Inverter circuit 7 Motor 101 AC charger 102 Rectifier circuit 103 Constant current charging circuit 106 Voltage detection circuit 107 Hysteresis circuit 108 Constant current control circuit 109 Isolator 110 OR Circuit 111 Measurement Circuit 112 D / A Conversion Circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H02J 7/10 B

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 assembled-battery charge control circuit that includes an over-voltage detection circuit that outputs an over-voltage detection signal, and that prevents over-charge of each battery that constitutes the assembled battery, wherein the over-voltage detection circuit has a terminal voltage of the battery that is a first voltage. When the terminal voltage falls below a second voltage lower than the first voltage, the output of the overvoltage detection signal is stopped. circuit. 2. The battery pack charge control circuit according to claim 1, wherein the measuring means measures the number of times the overvoltage detection signal is output from any one of the overvoltage detection circuits, and the measuring means measures the number of times. A battery pack charge control circuit, comprising: a charging current control unit configured to reduce a charging current supplied to the batteries constituting the battery pack as the number of times increases. 3. The assembled battery charging control circuit according to claim 1, wherein the overvoltage detection signals output from the overvoltage detection circuits are electrically insulated from each other, and the insulation means insulates the overvoltage detection signals from each other. An OR circuit that calculates a logical sum of the generated overvoltage detection signals, and the measuring unit measures the number of times according to a change in the output of the OR circuit. 4. The assembled battery charge control circuit according to claim 1, wherein the higher the voltage measured by the total voltage detection circuit that measures the voltage of the entire assembled battery and the higher the voltage of the assembled battery, the higher the voltage of the assembled battery. An assembled battery charging control circuit, comprising: a charging current control unit that reduces a charging current supplied to the battery that constitutes the battery.