JP2003309932A - Battery charger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve efficiency in charging of a unit cell by suppressing an electric energy which is taken out of a secondary battery from being consumed as energy loss while appropriately equalizing charging state among the unit cells constituting the secondary battery. <P>SOLUTION: An equalizer circuit 20 comprising a common transformer 22 is provided between a charger 14 and a secondary battery 12 comprising a plurality of unit cells 18 connected in series. A primary-side coil 26 of the common transformer 22 is connected to the secondary battery 12 through a diode 44 in which a forward direction means advancing toward the secondary battery 12. A plurality of secondary-side coils 28 are connected to corresponding unit cells 18 in parallel. A bypass 46 provided parallel to the diode 44 comprises a conduction switch 48. The conduction switch 48 operates to shut off the bypass 46 when the secondary battery 12 is charged while allowing it to be conductive when not charged. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery charger, and more particularly to extracting electric energy from a secondary battery composed of a plurality of unit cells connected in series and distributing the electric energy to each unit cell using a common transformer. By doing so, the present invention relates to a battery charger that equalizes the state of charge of each unit cell.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No. 2001-25174.
As disclosed in the publication, there is known a battery charger including a secondary battery composed of a plurality of unit cells connected in series. This device has a common transformer composed of a primary coil connected to a secondary battery and a secondary coil corresponding to each unit cell, and the electromotive force of any one unit cell exceeds a predetermined value. In this case, by driving the switching element, the surplus energy of the unit cell is supplied to another unit cell by using magnetic coupling by a common transformer.
In such a configuration, when the electromotive force of some unit cells rises excessively, the electric energy for that amount is distributed to the other unit cells to equalize the charging states of the unit cells. Therefore, according to the above-mentioned conventional device, it is possible to avoid overcharging only some of the unit cells, and it is possible to charge the unit cells in a well-balanced manner.

[0003]

By the way, in order to prevent the state of charge of the unit cells of the secondary battery from fluctuating, it is necessary to always carry out an equalizing process for taking out electric energy from the unit cells and distributing it to other unit cells. Is preferred. However, in such a configuration in which the equalization process is always performed, the energy loss caused in the process of distributing the electric energy taken out from the unit cell through the common transformer is increased, which causes a problem that the charging efficiency is lowered. .

The present invention has been made in view of the above points, and suppresses the consumption of electric energy extracted from the secondary battery as an energy loss, and at the same time, in each unit cell constituting the secondary battery. An object of the present invention is to provide a battery charging device capable of improving the charging efficiency when charging each unit cell by appropriately equalizing the state of charge.

[0005]

The above-mentioned object is defined in claim 1.
As described in (1), the secondary battery includes a plurality of unit cells connected in series, and the secondary battery has a common transformer connected to the primary side coil through a predetermined current path. An equalization circuit that distributes the electric energy supplied to the primary coil to each unit cell of the secondary battery by magnetically supplying the secondary coil of the common transformer corresponding to each unit cell of the secondary battery,
A battery charging device including: a flow of current from the secondary battery to the primary side coil of the common transformer via the predetermined current path is prohibited when the secondary battery is charged and permitted when not charged. This is achieved by a battery charger having a current flow path control means.

In the present invention, the flow of the current from the secondary battery to the primary side coil of the common transformer via the predetermined current path is prohibited when the secondary battery is charged and is permitted when the secondary battery is not charged. When the flow of such current is prohibited, electric energy cannot be taken out from the secondary battery to the common transformer, and the electric energy is not distributed through the common transformer. Therefore, the secondary battery is not charged when the secondary battery is charged. Energy loss due to the electric energy taken out from the next battery flowing through the common transformer does not occur. On the other hand, when the above-mentioned current flow is permitted, electric energy is extracted from the secondary battery to the common transformer, and the electric energy can be distributed to each unit cell via the common transformer. When the next battery is not charged, the state of charge of each unit cell is equalized. Therefore, according to the present invention, it is possible to appropriately equalize the charging states of the unit cells that form the secondary battery while suppressing the consumption of the electric energy extracted from the secondary battery as energy loss in the common transformer or the like. Therefore, the charging efficiency when charging each unit cell can be improved.

In this case, as described in claim 2, in the battery charging device according to claim 1, a control switch provided in the predetermined current path is provided, and the current flow path control means is provided with the predetermined current. If the path is cut off when the secondary battery is charged using the control switch and is made conductive when the secondary battery is not charged, the flow of current from the secondary battery to the primary coil of the common transformer via the predetermined current path is prevented. Can be prohibited or allowed.

Further, as described in claim 3, claim 1
In the battery charger described above, a diode that is provided in the predetermined current path and has a forward direction from a primary coil of the common transformer to the secondary battery, and a diode that is parallel to the predetermined current path in the predetermined current path. A bypass passage provided in, and a control switch provided in the bypass passage, the current flow path control means, the bypass passage is cut off at the time of charging the secondary battery using the control switch, If it is conducted during non-charging, the diode always allows the current to flow from the primary side coil of the common transformer to the secondary battery through the predetermined current path, and the operation of the control switch provided in the bypass passage. Electricity from the secondary battery to the primary side coil of the common transformer via the bypass passage of the predetermined current path It is possible to disable or enable the distribution.

According to a fourth aspect of the present invention, in the battery charging apparatus according to the second or third aspect, the control switch makes the predetermined current path conductive when the secondary battery is not charged and charges the secondary battery when charging. The switch may be a self-exciting switch that is cut off when a current flows.

Further, as described in claim 5, the above object is to provide a secondary battery constituted by a plurality of unit cells connected in series, and a primary side coil via the secondary battery and a predetermined current path. A common transformer to be connected is provided, and the electric energy supplied from the secondary battery to the primary coil is supplied to the secondary coil of the common transformer corresponding to each unit cell of the secondary battery by magnetic coupling. And an equalization circuit for distributing to each unit cell, whereby the flow of current from the secondary battery to the primary side coil of the common transformer via the predetermined current path is A battery having a current flow path control means for prohibiting the variation of the next battery between unit cells when it does not exceed a predetermined value and permitting it when the variation exceeds the predetermined value. It is achieved by collector.

In the present invention, the flow of the current from the secondary battery to the primary side coil of the common transformer through the predetermined current path is prohibited when the unit cell variation of the secondary battery does not exceed the predetermined value. , If the variation exceeds a certain level, it is permitted. If the flow of such a current is prohibited, it becomes impossible to take out the electric energy from the secondary battery to the common transformer, and since the electric energy is not distributed through the common transformer, the variation between the unit cells is predetermined. When it does not occur above, the energy loss caused by the electric energy taken out from the secondary battery flowing through the common transformer does not occur. On the other hand, when the above current flow is permitted, electric energy is extracted from the secondary battery to the common transformer, and the electric energy can be distributed to each unit cell via the common transformer. If the variation is more than a predetermined value, the charge states of the unit cells are equalized. Therefore, according to the present invention, it is possible to appropriately equalize the charging states of the unit cells that form the secondary battery while suppressing the consumption of the electric energy extracted from the secondary battery as energy loss in the common transformer or the like. Therefore, the charging efficiency when charging each unit cell can be improved.

In the present invention, the "variation between unit cells" refers to the variation in the state of charge (charging rate) of a plurality of unit cells, which is detected based on the voltage of each unit cell, for example.

In this case, as described in claim 6, in the battery charging device according to claim 5, a control switch provided in the predetermined current path is provided, and the current flow path control means is provided with the predetermined current. If the path between the unit cells of the secondary battery is not blocked by the control switch when the variation is not more than the predetermined value, and the path is made conductive when the variation is more than the predetermined value, the secondary path is used. It is possible to prohibit / permit the flow of current from the battery to the primary side coil of the common transformer via a predetermined current path.

Further, as described in claim 7, claim 5
In the battery charger described above, a diode that is provided in the predetermined current path and has a forward direction from a primary coil of the common transformer to the secondary battery, and a diode that is parallel to the predetermined current path in the predetermined current path. A bypass passage provided in the bypass passage, and a control switch provided in the bypass passage, the current flow path control means, the bypass passage using the control switch, there is a variation between the unit cells of the secondary battery. If it does not occur for more than the predetermined value, it is cut off, and if it occurs for more than the predetermined value, it is made to conduct, so that the diode from the primary coil of the common transformer to the secondary battery via the predetermined current path. The current is always allowed to flow, and the operation of the control switch provided in the bypass passage allows the secondary battery to maintain The flow of current to the common transformer primary coil through the bypass passage of the flow path can be disable or enable.

In these cases, as described in claim 8,
The battery charging device according to any one of claims 1 to 7, further comprising a charger that is connected to the secondary battery via the predetermined current path to charge the secondary battery, and the equalization circuit Further, if at least a part of the electric energy from the charger is distributed from the primary side coil of the common transformer to the secondary side coil by magnetic coupling to distribute to each unit cell of the secondary battery,
Since the electric energy is distributed to each unit cell through the common transformer when the secondary battery is charged by the charger, the charging state of each unit cell can be equalized without taking out the electric energy from the secondary battery.

[0016]

1 is a block diagram of a battery charging device 10 according to a first embodiment of the present invention. The battery charging device 10 of the present embodiment is installed in a vehicle. The vehicle includes a secondary battery 12 that functions as an in-vehicle battery,
Charger 14 such as motor generator and alternator
And an electric load 16 such as an auxiliary machine, an air conditioner, and a car navigation system. The secondary battery 12 is composed of a plurality (three in FIG. 1) of unit cells 18 connected in series, and is, for example, a nickel hydrogen battery or a lithium ion battery having an output voltage of about 12V. The secondary battery 12 includes the charger 14 and the electric load 1 described above.
6, the electric energy obtained by converting the kinetic energy of the vehicle during regenerative braking of the vehicle or generation of power by the vehicle engine is supplied from the charger 14 to be stored as electric power in each unit cell 18, and Each unit cell 18
The electric load 16 is operated by supplying the electric power stored in the electric load 16 to the electric load 16.

The battery charger 10 of this embodiment includes an equalizing circuit 20. The equalization circuit 20 is a circuit that equalizes the state of charge of each unit cell 18 of the secondary battery 12. The equalization circuit 20 is provided between the secondary battery 12 and the charger 14. The equalization circuit 20 includes a common transformer 22 and a main switch 24. The common transformer 22 is composed of a primary coil 26 and a secondary coil 28. A main switch 24 is connected in series to the primary coil 26 of the common transformer 22, and a circuit that connects a snubber circuit 34 including a resistor 30 and a capacitor 32 and a diode 36 in series is connected in parallel. The snubber circuit 34 and the diode 36 have a function of absorbing the energy of the leakage inductance generated in the common transformer 22 when the main switch 24 is turned off. The above-described charger 14 is connected between the terminal of the primary coil 26 opposite to the main switch 24 side and the terminal of the main switch 24 opposite to the primary coil 26 side.

The secondary coil 28 of the common transformer 22 is
A plurality (three in FIG. 1) is provided corresponding to each unit cell 18 of the secondary battery 12. Each secondary coil 28 is formed in a reverse phase winding with respect to the primary coil 26. A rectifier circuit 38 including a diode is connected in series to each secondary coil 28, and a corresponding unit cell 18 is connected in parallel. Rectifier circuit 3
Reference numeral 8 is a circuit for converting the alternating current induced in the secondary coil 28 into the direct current by the magnetic coupling by the primary coil 26. The unit cell 18 can store the DC power from the rectifier circuit 38.

The primary side of the common transformer 22 and the secondary battery 12 are connected via current paths 40 and 42. The current path 40 is connected to the terminal of the primary coil 26 of the common transformer 22 on the side opposite to the main switch 24 side, and is connected to the + terminal side of the secondary battery 12. Further, the current path 42 is connected to the terminal on the side opposite to the primary coil 26 side of the main switch 24, and is also connected to the-terminal side of the secondary battery 12.

A diode 44 is provided in the middle of the current path 40.
Is provided. The diode 44 is the common transformer 2
This is a diode whose forward direction is the direction from the primary coil 26 of 2 to the + terminal side of the secondary battery 12. The current path 40 includes a bypass passage 46 in parallel with the diode 44.
Is provided. The bypass passage 46 is provided with a conduction switch 48 that cuts off / conducts the path.
The conduction switch 48 is composed of an electromagnetic switch, a bipolar transistor, a MOS-FET, etc., and shuts off the bypass passage 46 when it is in the off state, and makes the bypass passage 46 conductive when it is in the on state.

The conduction switch 48 and the above-mentioned main switch 24 are each an electronic control unit (hereinafter referred to as ECU).
50). Main switch 24
PWM (Pulse Widt) according to a command from the ECU 50.
h Modulation) It is turned on / off by control. Further, the continuity switch 46 is turned on / off according to a command from the ECU 50.

A charger voltage detection circuit 52 and a unit cell voltage detection circuit 54 are also connected to the ECU 50. The charger voltage detection circuit 52 is provided in parallel with the charger 14, and outputs a signal according to the voltage between the terminals of the charger 14. The unit cell voltage detection circuit 54 is provided for each unit cell 18, and outputs a signal according to the terminal voltage of the corresponding unit cell 18. Based on the output signal of the charger voltage detection circuit 52, the ECU 50 determines whether the charger 14
Of the unit cell voltage detection circuit 54 and the inter-terminal voltages VC1, VC2, ..., VCn (n = 3 in the present embodiment) of each unit cell 18 are detected based on the output signal of the unit cell voltage detection circuit 54. VC * (however, * = 1, 2, ...
.., n) is added to detect the total voltage V2 of the unit cells 18 (that is, the total voltage of the secondary battery 12). The ECU 50 performs PWM control of the main switch 24 and ON / OFF control of the conduction switch 48 based on each detection result.

FIG. 2 shows a battery charger 10 of this embodiment.
The figure for demonstrating operation | movement of is shown. Incidentally, FIG.
2A shows the case where the main switch 24 is turned on, and FIG. 2B shows the case where the main switch 24 is turned off.

In the configuration of the present embodiment, even if the conduction switch 48 is off, the function of the diode 44 allows the current to flow from the charger 14 to the secondary battery 12 through the current path 40. Therefore, the secondary battery 12 configured by the unit cells 18 connected in series is charged by receiving the supply of electric energy from the charger 14 via the current path 40 and the diode 44.
Further, the secondary battery 12 is discharged by supplying electric energy to the electric load 16.

When the main switch 24 of the equalizing circuit 20 is turned on as shown in FIG. 2 (A) under the condition that the secondary battery 12 is storing electric power, the conduction switch 48 is turned on.
Assuming that is on, the discharge current I flows from the + terminal side of the secondary battery 12 to the primary coil 26 of the common transformer 22 via the bypass passage 46 as indicated by the dashed arrow. At this time, the discharge current I is the sum of the discharge currents of the unit cells 18. Primary coil 2
When a current is supplied to 6, the primary side of the common transformer 22 is filled with the corresponding electric energy.

When the main switch 24 changes from this state to the off state as shown in FIG. 2B, an electromotive force is induced in each secondary coil 28 by the electric energy charged in the primary coil 26 of the common transformer 22. To be done. In this case, a voltage exceeding the inter-terminal voltage VC * acts on each unit cell 18, and the charging currents I1, I2, ..., In are supplied from the secondary coil 28 as indicated by the broken line arrow. At this time, the charging currents I1 and I flowing through each unit cell 18
2, ..., In is the secondary coil 28 corresponding to itself.
The value becomes a value corresponding to the differential pressure between the electromotive force induced in and the self-terminal voltage VC *. That is, since the unit cell 18 having a large inter-terminal voltage VC has a small differential pressure with respect to the electromotive force,
A relatively small charging current I * flows, while the unit cell 18 having a small terminal voltage VC has a large differential pressure with respect to the electromotive force, so that a relatively large charging current I * (however, *
= 1, 2, ..., N) flows.

Thus, in the configuration of this embodiment,
When the main switch 24 is turned on, the secondary battery 1
The electric energy is taken out from each unit cell 18 of No. 2 and is charged into the primary side of the common transformer 22, and when the main switch 24 is turned off, the magnetic coupling by the common transformer 22 is used to make each unit cell 18 from the secondary side. Is supplied with electric energy corresponding to the voltage VC * between the terminals of the unit cell 18.

In the unit cell 18, the larger the inter-terminal voltage VC *, the larger the remaining capacity, and the charged state becomes closer to full charge. That is, the voltage VC * between the terminals of the unit cell 18 is
The value depends on the state of charge. Therefore, in the configuration of the present embodiment, when the main switch 24 is turned on, electric energy is equally extracted from each unit cell 18, while when the main switch 24 is turned off, the unit cells 18 having a relatively small remaining capacity are discharged. A relatively large amount of electric energy is supplied, and a relatively small amount of electric energy is supplied to the unit cell 18 having a relatively large remaining capacity.

Therefore, by repeatedly turning on and off the main switch 24, it is possible to eliminate the variation in the charging state of each unit cell 18 constituting the secondary battery 12, and to make the charging state uniform. You can Thus, according to the battery charger 10 of the present embodiment,
Since it is possible to prevent only some of the unit cells 18 from being overcharged and the unit cells 18 can be charged in a well-balanced manner, it is possible to avoid a situation in which the entire battery 12 cannot be charged due to overcharging. Therefore, the entire secondary battery 12 can be efficiently charged and discharged. Hereinafter, by turning on / off the main switch 24, the unit cell 1
The process of 8 equalization is referred to as “equalization process”.

By the way, in order to prevent the variation in the charged state of each unit cell 18 constituting the secondary battery 12, the secondary battery 12 is distributed by distributing the electric energy extracted from each unit cell through the common transformer 22.
It is desirable to always perform the equalization processing of. However, since energy loss occurs in the process in which the electric energy extracted from the unit cell 18 is distributed to each unit cell through the common transformer 22, the common transformer is always used in the configuration in which the equalization process is performed as described above. There is an inconvenience that the energy loss generated in 22 and the current path 40 increases, and the charging efficiency of the secondary battery 12 decreases.

Therefore, the present embodiment is characterized in that the charging efficiency of the secondary battery 12 is improved by suppressing the consumption of the electric energy extracted from the secondary battery 12 as an energy loss. ing. Hereinafter, the characteristic part of the present embodiment will be described with reference to FIG.

In the configuration of the present embodiment, when the charger 14 charges the secondary battery 12, the charging current thereof, together with the current path 40, is the primary side of the common transformer 22 when the main switch 24 is in the ON state. It also flows to the coil 26. When a current is supplied to the primary coil 26, the electric energy for that amount is charged into the primary side of the common transformer 22. When the main switch 24 is turned off from such a state, an electromotive force is induced in each secondary coil 28 of the common transformer 22, and a charging current is supplied to each unit cell 18 of the secondary battery 12. At this time, each charging current to each unit cell 18 has a value according to the differential pressure between the electromotive force induced in the secondary coil 28 corresponding to itself and the terminal voltage VC * of itself.

Therefore, according to this embodiment, the charger 14
Also when the secondary battery 12 is charged by the common transformer 22, as in the case where the electric energy is taken out from the unit cells 18 of the secondary battery 12 to forcibly equalize the charge states of the unit cells 18. The coupling can be used to distribute electrical energy to each unit cell 18 depending on its state of charge. Therefore, when the secondary battery 12 is charged by the charger 14, the charging state of each unit cell 18 is supplied to the secondary battery 12 by supplying a part of the charging current by the charger 14 through the common transformer 22. Are charged so that they are equalized. In this regard, when the secondary battery 12 is charged by the charger 14, each unit cell 18
It is not necessary to forcibly extract the electric energy from each unit cell 18 to the primary side of the common transformer 22 in order to equalize the charging states of the.

In this embodiment, a current path 40 is provided between the secondary battery 12 and the primary side of the common transformer 22. In the current path 40, a diode 44 whose forward direction is a direction from the primary coil 26 to the + terminal side of the secondary battery 12, and a conduction switch 48 which interrupts / conducts a bypass passage 46 provided in parallel with the diode 44. Is provided. When the conduction switch 48 is in the ON state, the bypass passage 46 is in conduction, so that current flows from the charger 14 side to the secondary battery 12 via the current path 40, and from the secondary battery 12 to the current path 4.
The flow of current to the charger 14 side through 0 is both permitted. On the other hand, when the continuity switch 48 is off,
Since the bypass passage 46 is cut off, the flow of current from the charger 14 side to the secondary battery 12 via the current path 40 and the diode 44 is allowed, while the charger 14 from the secondary battery 12 via the current path 40 is allowed. Circulation of current to the side is prohibited.

Therefore, the secondary battery 1 by the charger 14
When the secondary battery 12 is not charged, the conduction switch 48 is maintained in the on state, while when the secondary battery 12 is charged, the conduction switch 48 is turned off. When the battery 12 is not charged, the current is allowed to flow from the secondary battery 12 to the charger 14 side through the current path 40 and the bypass passage 46, while when the secondary battery 12 is charged, the current path 40 flows from the secondary battery 12 to the current path 40. Since the current flow to the charger 14 side via the battery is prohibited, the secondary battery 1 by the charger 14 is prevented.
Under the situation where the second charging is performed, it is avoided that the electric energy is taken out from each unit cell 18 to the primary side of the common transformer 22 for equalizing the charging state of each unit cell 18. .

In such a configuration, when the secondary battery 12 is not charged by the charger 14, the electric energy is taken out from each unit cell 18 to the primary side of the common transformer 22 and distributed to each unit cell 18, thereby distributing the secondary battery. 12
Equalization processing can be performed, and at the time of charging the secondary battery 12, each unit cell 18 is connected to the common transformer 2.
It is possible to avoid the generation of energy loss that occurs in the process in which the electric energy from each unit cell 18 is distributed to each unit cell 18 via the common transformer 22 without taking out the electric energy to the primary side of the second unit 2. . Therefore, if the state of the conduction switch 48 is switched depending on whether or not the secondary battery 12 is charged by the charger 14 as described above, the electrical energy extracted from the secondary battery 12 is consumed as energy loss. It is possible to appropriately equalize the state of charge of each unit cell 18 constituting the secondary battery 12 while suppressing this, and thereby to improve the charging efficiency of the unit cell 18.

FIG. 3 shows a flow chart of an example of a control routine executed by the ECU 50 in this embodiment in order to realize the above function. The routine shown in FIG. 3 is a routine that is repeatedly started every predetermined time. When the routine shown in FIG. 3 is started, the process of step 100 is first executed.

In step 100, the inter-terminal voltage V1 of the charger 14 detected based on the output signal of the charger voltage detection circuit 52 is input, and also detected based on the output signal of the unit cell voltage detection circuit 54. , VCn between the terminals of each unit cell 18 are input, and the total voltage V2 (= VC1 + VC2 + ... + VC) of the secondary battery 12 obtained by adding them
n) is input.

In step 102, whether or not the charger 14 is in the charging operation, specifically, the inter-terminal voltage V1 of the charger 14 input in the above step 100 becomes the total voltage V2 of the secondary battery 12. In comparison, it is determined whether or not it is larger than the predetermined value α. The predetermined value α is the minimum positive voltage that allows the charger 14 to determine that the secondary battery 12 can be charged. If V1 ≧ V2 + α is satisfied, it can be determined that the charger 14 is in a state in which the secondary battery 12 can be charged. Therefore, if such a determination is made, the process of step 104 is executed next. On the other hand, when V1 ≧ V2 + α is not established, it can be determined that the charger 14 is not in a state in which the secondary battery 12 can be charged. Therefore, if such a determination is made, the process of step 106 is executed next.

In step 104, the main switch 24
Is duty-controlled by PWM control, and a process of turning off the conduction switch 48 is executed. After the processing of this step 104 is executed, the common transformer 22
While the flow of current from the primary side of the secondary battery 12 through the current path 40 and the diode 44 is allowed,
Since the bypass passage 46 is cut off by turning off the conduction switch 48, the flow of current from the secondary battery 12 to the primary side of the common transformer 22 via the current path 40 is prohibited. When the process of this step 104 is completed, the routine of this time is ended.

In step 106, the charging states of the unit cells 18 of the secondary battery 12 need to be equalized, and whether or not the cell balance correction needs to be performed on the secondary battery 12, specifically, It is determined whether or not the difference between any two of the inter-terminal voltages VC1, VC2, ..., VCn of each unit cell 18 is greater than or equal to a predetermined value β. It should be noted that the predetermined value β is the minimum voltage difference with which it can be determined that the cell balance correction needs to be performed. As a result, | VC1-VC2 |
≧ β, | VC2-VC3 | ≧ β, and | VC3-VC1
If it is determined that none of | ≧ β is satisfied, it is not necessary to perform cell balance correction, and therefore, in step 10
Process 8 is executed. On the other hand, | VC1-VC2 | ≧
β, | VC2-VC3 | ≧ β, and | VC3-VC1 |
If it is determined that any one of ≧ β is satisfied, the cell balance correction needs to be performed.
The process of is executed.

At step 108, the main switch 24
The process of turning off the duty drive and turning it off and turning off the conduction switch 48 is also executed. This step 1
When the process of 08 is executed, the equalization process of the secondary battery 22 is not performed thereafter, and the flow of the current from the secondary battery 12 to the primary side of the common transformer 22 via the current path 40 is prohibited. . When the process of step 108 is completed, the routine of this time is ended.

In step 110, the main switch 24
Is duty-controlled by PWM control, and a process of turning on the conduction switch 48 is executed. After the processing of this step 110 is executed, the continuity switch 48
Since the bypass passage 46 is turned on when the common transformer 2 is turned on, the common transformer 2 from the secondary battery 12 through the current path 40 is turned on.
2 is allowed to flow to the primary side. This step 1
When the process of 10 ends, the routine of this time is ended.

According to the routine shown in FIG. 3, when the secondary battery 12 is charged by the charger 14, the main switch 24 is duty-driven and the conduction switch 4 is operated.
8 is turned off, and the secondary battery 12 is charged by the charger 14
If the battery is not charged by, the main switch 24 can be duty-driven and the conduction switch 48 can be turned on, on the condition that the cell balance of the secondary battery 12 needs to be corrected.

In this structure, when the secondary battery 12 is charged by the charger 14, each unit cell 1
Each unit cell 18 for performing equalization processing of the charge state of 8
Since it is impossible to extract the electric energy from the main transformer 22 to the primary side of the common transformer 22, the electric energy extracted from each unit cell 18 is generated in the process of being distributed to each unit cell 18 via the common transformer 22. Generation of energy loss can be avoided. In this case, an increase in energy loss with respect to the electric energy extracted from the secondary battery 12 is suppressed. Further, in the above configuration, when the secondary battery 12 is not charged by the charger 14, when the cell balance correction of the secondary battery 12 is required, each unit cell 18 is transferred to the primary side of the common transformer 22. Since it is possible to take out electric energy, it is possible to perform equalization processing on each unit cell 18.

Therefore, the battery charger 10 of the present embodiment.
According to this, the charging state of each unit cell 18 is suppressed while suppressing the consumption of the electric energy extracted from the secondary battery 12 as an energy loss, as compared with the configuration in which the equalization process of the secondary battery 12 is always performed. Can be properly equalized. Therefore, in this embodiment, it is possible to improve the charging efficiency when charging the unit cell 18 of the secondary battery 12.

In the configuration of this embodiment, the charger 1
The main switch 24 is duty-driven when the secondary battery 12 is charged by the battery charger 4.
Part of the charging current of 4 is supplied to each unit cell 18 of the secondary battery 12 by magnetic coupling by the common transformer 22. That is, the secondary battery 12 is charged so that the charge states of the unit cells 18 are equalized.
For this reason, when the secondary battery 12 is charged by the charger 14, it is possible to realize equalization of the charging state of each unit cell 18 without taking out electric energy from each unit cell 18. Therefore, in the battery charger 10 of the present embodiment, each unit cell 18 of the secondary battery 12 is
It is possible to promote the equalization of.

Further, according to the routine shown in FIG.
When it is not necessary to perform the cell balance correction of the secondary battery 12 under the situation where the secondary battery 12 is not charged by the charger 14, both the main switch 24 and the conduction switch 48 can be kept off. In such a configuration, when the charging state of each unit cell 18 is maintained in a well-balanced state under the condition that the charger 14 is not charging, the equalization process itself is not performed and the bypass passage 46 is blocked.

If each unit cell 18 is charged in a well-balanced manner, it is not necessary to carry out equalization processing for balancing the charged state, and it is also unnecessary to make the bypass passage 46 conductive. Therefore, according to the battery charger 10 of the present embodiment, when the unit cells 18 are charged in a well-balanced state under the condition that the charger 14 is not charging, the secondary battery 12 passes through the current path 40. Current does not flow to the primary side of the common transformer 22, and
Since no current flows to each unit cell 18 of the secondary battery 12 via the common transformer 22, it is possible to prevent the equalization process of the secondary battery 12 from being wastefully performed, and the equalization process is performed. It is possible to avoid the occurrence of energy loss due to it.

In the first embodiment, the current path 40 is the "predetermined current path" described in the claims.
The diode 44 is a “diode” described in the claims, the bypass passage 46 is a “bypass passage” described in the claims, and the conduction switch 48 is a “control switch” described in the claims. , Respectively. Further, the ECU 50 cuts off / conducts the current path 40 by turning on / off the conduction switch 48 according to the processing of the routine shown in FIG. 3, whereby the “current distribution path control means” described in the claims is realized. There is.

By the way, in the first embodiment,
In a situation where the secondary battery 12 is not charged by the charger 14, the conduction switch 48 is kept off when the cell balance correction of the secondary battery 12 does not need to be performed, and the cell balance correction needs to be performed. Although the conduction switch 48 is turned on, the conduction switch 48 may be always turned on when the secondary battery 12 is not charged by the charger 14.

Further, in the above-described first embodiment, the conduction switch 48 is turned off when the secondary battery 12 is charged by the charger 14, but the charging state of each unit cell 18 varies. In the case where the charging is significant, the conduction switch 48 may be turned on even under the condition where the charging is performed. In this case, since the variation in the charge state of each unit cell 18 is promoted, the charge state can be quickly equalized.

Next, a second embodiment of the present invention will be described with reference to FIG. 4 together with FIGS. 1 and 3 above. The system of this embodiment is the battery charger 10 shown in FIG.
In the above, it is realized by causing the ECU 50 to execute the routine shown in FIG.

In the first embodiment described above, the secondary battery 1
When the battery 2 is charged by the charger 14, the conduction switch 48 is turned off regardless of whether or not the cell balance correction needs to be performed, and the common transformer 22 from the secondary battery 12 through the current path 40 and the bypass path 46. When the secondary battery 12 is not charged by the charger 14 while the flow of the current to the primary side of the battery is prohibited, the conduction switch 48 is provided on the condition that the cell balance correction needs to be performed.
Is turned on to allow the current to flow.

On the other hand, in this embodiment, when it is necessary to correct the cell balance of the secondary battery 12, the conduction switch 48 is turned on regardless of whether the secondary battery 12 is charged or not. Common transformer 2 from battery 12 via current path 40 and bypass path 46
While allowing the flow of the current to the primary side of No. 2, when it is not necessary to perform the cell balance correction, the conduction switch 48 is turned off to prohibit the flow of the current.

A unit cell 18 constituting the secondary battery 12
In the case where the variation in the charge state is relatively large, it is necessary to perform the cell balance correction, and the electric energy is extracted from each unit cell 18 to the primary side of the common transformer 22 via the current path 40 and the electric energy is extracted. Is preferably distributed to each unit cell 18 via the common transformer 22 to promote the equalization process of the secondary battery 12. On the other hand, when the variation in the charged state of the unit cell 18 is relatively small, it is not always necessary to perform the cell balance correction. That is, in order to equalize the charging states of the unit cells 18, it is not necessary to frequently take out electric energy from the unit cells 18 to the primary side of the common transformer 22, and the charging states of the unit cells 18 vary. It suffices to carry out such removal only when

In this respect, in the structure of the present embodiment, when the unit cell 18 has a large variation in the charged state and the cell balance correction needs to be performed, the primary of the common transformer 22 from the secondary battery 12 through the current path 40. Since the electric current is allowed to flow to the side, the equalization process of the secondary battery 12 can be performed by extracting the electric energy from each unit cell 18 to the primary side of the common transformer 22 and distributing the electric energy to each unit cell 18. it can. When the unit cell 18 has a small variation in the state of charge and cell balance correction is not required, the current flow is prohibited. Therefore, the electric energy is taken out from each unit cell 18 to the primary side of the common transformer 22. Therefore, it is possible to avoid the occurrence of energy loss that occurs in the process in which the electric energy from each unit cell 18 is distributed to each unit cell 18 via the common transformer 22.

Therefore, if the conduction switch 48 is switched according to the variation in the charge state between the unit cells 18 of the secondary battery 12 as described above, the electric energy extracted from the secondary battery 12 is consumed as energy loss. It is possible to appropriately equalize the state of charge of each unit cell 18 that configures the secondary battery 12 while suppressing this, and thereby improve the charging efficiency of the unit cell 18.

FIG. 4 shows a flowchart of an example of a control routine executed by the ECU 50 in the present embodiment in order to realize the above function. The routine shown in FIG. 4 is a routine that is repeatedly started every predetermined time. When the routine shown in FIG. 4 is started, the process of step 150 is first executed.

In step 150, as in step 100 of the routine shown in FIG. 3, the terminal voltage V1 of the charger 14 is input and the terminal voltages VC1, VC2, ... Of the unit cells 18 are input. VCn is input, and the total voltage V2 (= VC1 + VC2 + ... + VCn) of the secondary battery 12 obtained by adding them is input.

In step 152, the above step 150
The terminal-to-terminal voltages VC1 and VC of each unit cell 18 input in
It is determined whether the difference between any two of 2, ..., VCn is greater than or equal to a predetermined value β. It should be noted that the predetermined value β is the minimum voltage difference with which it can be determined that the cell balance correction needs to be performed. As a result, | VC1-VC2 | ≧ β, | VC2-V
When it is determined that any one of C3 | ≧ β and | VC3-VC1 | ≧ β is established, the process of step 154 is executed next. On the other hand, | VC1-VC2 | ≧ β, | V
If it is determined that neither C2-VC3 | ≧ β or | VC3-VC1 | ≧ β holds, then step 1
The processing of 56 is executed.

At step 154, the main switch 24
Is duty-controlled by PWM control, and a process of turning on the conduction switch 48 is executed. When the processing of this step 154 is executed, the continuity switch 48
Since the bypass passage 46 is turned on when the common transformer 2 is turned on, the common transformer 2 from the secondary battery 12 through the current path 40 is turned on.
2 is allowed to flow to the primary side. This step 1
When the processing of 54 ends, the routine of this time is ended.

In step 156, it is determined whether or not the charger 14 is in the charging operation. Specifically, the terminal voltage V1 of the charger 14 input in step 150 is set to the total voltage V2 of the secondary battery 12. In comparison, it is determined whether or not it is larger than the predetermined value α. The predetermined value α is the minimum positive voltage that allows the charger 14 to determine that the secondary battery 12 can be charged. If V1 ≧ V2 + α holds, it can be determined that the charger 14 is in a state in which the secondary battery 12 can be charged, and if such a determination is made, the process of step 158 is executed next. On the other hand, when V1 ≧ V2 + α is not established, it can be determined that the charger 14 is not in a state in which the secondary battery 12 can be charged. Therefore, if such a determination is made, the process of step 160 is executed next.

At step 158, the main switch 24
Is duty-controlled by PWM control, and a process of turning off the conduction switch 48 is executed. After the processing of this step 158 is executed, the common transformer 22
While the flow of current from the primary side of the secondary battery 12 through the current path 40 and the diode 44 is allowed,
Since the bypass passage 46 is cut off by turning off the conduction switch 48, the flow of current from the secondary battery 12 to the primary side of the common transformer 22 via the current path 40 is prohibited. When the processing of this step 158 ends, the routine of this time is ended.

At step 160, the main switch 24
The process of turning off the duty drive and turning it off and turning off the conduction switch 48 is also executed. This step 1
When the process of 60 is executed, the equalization process of the secondary battery 22 is not performed thereafter, and the flow of the current from the secondary battery 12 to the primary side of the common transformer 22 via the current path 40 is prohibited. . When the processing of this step 160 ends, this routine ends.

According to the routine shown in FIG. 4, the conduction switch 48 is turned on when the variation in the charge state between the unit cells 18 constituting the secondary battery 12 is relatively large and the cell balance correction needs to be performed. In addition to duty-driving the main switch 24, the conduction switch 48 can be turned off when the variation in the charge state between the unit cells 18 is relatively small and cell balance correction is not required.

In such a configuration, when the cell balance correction needs to be performed, the bypass passage 46 is made conductive so that the electric energy can be taken out from each unit cell 18 to the primary side of the common transformer 22. Since it is possible, it is possible to perform the equalization processing of the charge states of the unit cells 18. In addition, when it is not necessary to perform cell balance correction, it is impossible to extract the electric energy because the bypass passage 46 is blocked, so that the electric energy extracted from each unit cell 18 is shared by the common transformer. It is possible to avoid energy loss that occurs in the process of being distributed to each unit cell 18 via 22.

Therefore, the battery charger 10 of the present embodiment.
According to the above, similarly to the configuration of the first embodiment, the electric energy extracted from the secondary battery 12 is consumed as energy loss as compared with the configuration in which the equalization process of the secondary battery 12 is always performed. While suppressing, it is possible to appropriately equalize the charge states of the unit cells 18. Therefore, in this embodiment, it is possible to improve the charging efficiency when charging the unit cell 18 of the secondary battery 12.

Further, according to the routine shown in FIG.
Even when the cell balance correction of the secondary battery 12 is not required, the main switch 24 can be duty-driven when the secondary battery 12 is charged by the charger 14. That is, the secondary battery 12
Is charged by the charger 14, the main switch 24 can be duty-driven regardless of whether or not the cell balance correction needs to be performed.

In such a configuration, when the secondary battery 12 is charged by the charger 14, a part of the charging current by the charger 14 is distributed and supplied to each unit cell 18 of the secondary battery 12 by magnetic coupling by the common transformer 22. The secondary battery 12 is charged so that the charge states of the unit cells 18 are equalized. In this case, even if the electric energy is not taken out from each unit cell 18 for cell balance correction, the equalization of the charge state of each unit cell 18 is realized. Therefore, the battery charging device 1 of the present embodiment
In 0, equalization of each unit cell 18 of the secondary battery 12 can be promoted.

In this case, when the variation in charging between the unit cells 18 is relatively small, a part of the charging current by the charger 14 is distributed and supplied to each unit cell 18 through the common transformer 22, so that the loss is small. Only mild equalization is done. On the other hand, when the charging variation between the unit cells 18 is relatively large, a part of the charging current by the charger 14 is distributed to each unit cell 18 through the common transformer 22, and the secondary battery 12 passes through the current path 40. By the distribution and supply of the current taken out to the primary side of the common transformer 22 to each unit cell 18 through the common transformer 22, the equalization processing having a greater equalization effect is performed.
That is, when the variation in charging is relatively small, the energy loss is small, but the equalization effect is small, and when the variation in charging is relatively large, the energy loss is large, but the equalization effect is large. By performing this, it is possible to realize a plurality of equalization processes in which the magnitude of the equalizing action is different depending on the magnitude of the charging variation of the unit cells 18, and it is possible to achieve both equalization of the unit cells 18 and reduction of energy loss. be able to.

Further, according to the routine shown in FIG.
When it is not necessary to correct the cell balance of the secondary battery 12 and the secondary battery 12 is not charged by the charger 14, both the main switch 24 and the conduction switch 48 can be turned off. In such a configuration, when the state of charge of each unit cell 18 is maintained in a well-balanced state and the charger 14 is not charging, the equalization process itself is not performed and the bypass passage 46 is blocked.

Therefore, the battery charger 10 of the present embodiment.
According to this, when the charge state of each unit cell 18 is maintained in a well-balanced state and the charger 14 is not in the charging operation, the common transformer 22 passes from the secondary battery 12 via the current path 40.
Since no current flows to the primary side of the secondary battery and no current flows to each unit cell 18 of the secondary battery 12 via the common transformer 22, it is possible to prevent wasteful equalization processing of the secondary battery 12. It is possible to avoid the occurrence of energy loss due to the equalization process.

In the second embodiment, the inter-terminal voltages VC1, VC2, ..., VCn of each unit cell 18 are set.
The difference between any two of the above corresponds to “variation between unit cells”, and the ECU 50 turns off / on the current path 40 by turning on / off the conduction switch 48 according to the processing of the routine shown in FIG. The "current distribution path control means" described in the claims is realized.

By the way, in the first and second embodiments, it is determined whether or not the cell balance of the secondary battery 12 needs to be corrected by determining the inter-terminal voltage VC of each unit cell 18.
1, VC2, ..., VCn is determined based on whether or not a difference between the two is equal to or more than a predetermined value β. However, the maximum value and the minimum value among the terminal voltages of all the unit cells 18 are determined. It may be determined based on whether or not the difference between and is greater than or equal to a predetermined value.

Next, referring to FIG. 5 together with FIG.
A third embodiment of the present invention will be described.

In the first and second embodiments described above, the common transformer 22 from the secondary battery 12 through the current path 40 is used.
The permission / prohibition of the current flow to the primary side is switched by the ON / OFF command to the conduction switch 48 from the ECU 50. On the other hand, in the present embodiment, depending on whether or not the switch is excited by the charging current when the secondary battery 12 is charged by the charger 14, the above-mentioned permission / prohibition of current flow is permitted. Switches.

FIG. 5 shows a battery charger 20 of this embodiment.
The block diagram of 0 is shown. In FIG. 5, the same parts as those shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted or simplified. The battery charging device 200 of the present embodiment is mounted on a vehicle and includes an equalizing circuit 20 provided between the secondary battery 12 and the charger 14. The charger 14 includes the primary coil 26 of the common transformer 22 of the equalization circuit 20 via the diode 202.
And the current path 204. The diode 202 is a diode whose forward direction is the direction from the + terminal side of the charger 14 toward the primary coil 26.

In the middle of the current path 204, the electromagnetic relay 2
06 is provided. The electromagnetic relay 206 includes a coil unit 208 and a switch unit 210. One end of the coil portion 208 is connected to the charger 14, and the other end is grounded. The switch unit 210 is provided in the bypass passage 46 provided in the current path 40. The switch unit 210 of the electromagnetic relay 206 is turned off when a current flows through the coil unit 208, shuts off the bypass passage 46, and is turned on when a current does not flow through the coil unit 208, and makes the bypass passage 46 conductive.

In the above structure, when the charger 14 charges the secondary battery 12, the charging current is equal to the charging current of the charger 14.
To the secondary battery 12 via the diode 202 and the diode 44. Therefore, the secondary battery 12
Is charged by being supplied with electric energy from the charger 14.

When the charger 14 charges the secondary battery 12, part of the charging current flows through the current path 204 to the coil portion 208 of the electromagnetic relay 206.
When current flows through the coil unit 208, the electromagnetic relay 206
The switch unit 210 is turned off. That is, the charger 1
When the secondary battery 12 is charged by No. 4, the bypass passage 46 is blocked by the function of the electromagnetic relay 206, so that the current flows from the secondary battery 12 to the primary side of the common transformer 22 via the current path 40. prohibited.

On the other hand, when the charger 14 does not charge the secondary battery 12, the coil portion 208 of the electromagnetic relay 206
Current does not flow through. When the current does not flow through the coil unit 208, the switch unit 210 is turned on. That is,
When the secondary battery 12 is not charged by the charger 14, the bypass passage 46 is provided by the function of the electromagnetic relay 206.
Is conducted, the current path 40 from the secondary battery 12
Current is allowed to flow to the primary side of the common transformer 22 via the.

Further, in this embodiment, the ECU 50 is
The main switch 24 is driven according to the routine shown in FIG. Specifically, the secondary battery 12 is the charger 14
When the secondary battery 12 is charged by the charger 14, and when it is necessary to perform the cell balance correction under the condition that the secondary battery 12 is not charged by the charger 14, the main switch 24 is duty-driven and the secondary battery 12 is charged by the charger 14. The main switch 24 is turned off when it is not necessary to perform the cell balance correction under the condition that the battery is not charged.

Therefore, in the present embodiment, the charger 14
When the secondary battery 12 is charged by, the electric energy cannot be taken out from each unit cell 18 to the primary side of the common transformer 22 for equalizing the charge state of each unit cell 18. . Therefore, at the time of charging the secondary battery 12, the occurrence of energy loss that occurs in the process in which the electric energy extracted from each unit cell 18 is distributed to each unit cell 18 via the common transformer 22 is avoided. Further, in the present embodiment, when the secondary battery 12 is not charged by the charger 14, when the cell balance correction of the secondary battery 12 is required, each unit cell 18 is transferred to the primary side of the common transformer 22. It is possible to extract electrical energy. Therefore, when the secondary battery 12 is not charged, the unit cells 18 can be equalized.

Therefore, the battery charger 20 of the present embodiment.
Also in 0, as in the battery charger 10 of the first embodiment, the electric energy extracted from the secondary battery 12 is consumed as energy loss as compared with the configuration in which the equalization process of the secondary battery 12 is always performed. While suppressing
The charging states of the unit cells 18 can be appropriately equalized, and thus, the charging efficiency when charging the unit cells 18 of the secondary battery 12 can be improved.

In the configuration of this embodiment as well, the charger 1
Since the main switch 24 is duty-driven when the secondary battery 12 is charged by No. 4, the secondary battery 12 is charged so that the charging states of the respective unit cells 18 are equalized. Therefore, also in the battery charger 200 of the present embodiment, when the secondary battery 12 is charged by the charger 14, the unit cells 18 have the same charging state without taking out electrical energy from the unit cells 18. The unit cells 18 can be realized, and the equalization of the unit cells 18 can be promoted.

In addition, the secondary battery 12 by the charger 14
Common transformer 2 under the condition that the battery is not charged
Assuming that current flows from the primary side of the secondary coil 2 to the coil section 208 of the electromagnetic relay 206, the bypass passage 46 is cut off, and the current flows from the secondary battery 12 to the primary side of the common transformer 22 via the current path 40. A situation occurs where it is prohibited. In the present embodiment, as described above, the charger 14
And the primary side of the common transformer 22 are provided with a diode 202 whose forward direction is from the charger 14 to the primary side of the common transformer 22. Therefore, the current flowing from the secondary battery 12 to the primary side of the common transformer 22 is prevented from further flowing to the coil section 208 of the electromagnetic relay 206 via the charger 14 side and the current path 204, and the secondary battery 12 is prevented. It is prevented that the current is unnecessarily prohibited from flowing to the primary side of the common transformer 22 via the current path 40.

In the third embodiment described above, the electromagnetic relay 206 that cuts off / conducts the current path 40 to the “control switch” described in the claims is the switch section 210 of the electromagnetic relay 206. Each corresponds to the "current distribution path control means" described in the range.

By the way, in the first to third embodiments, the equalizing circuit 20 is connected to the secondary battery 12 and the charger 14.
However, the present invention is not limited to this, and the equalizing circuit 20 may be connected only to the secondary battery 12 without being connected to the charger 14. In such a configuration, the conduction switch 48 or the switch section 210 of the electromagnetic relay 206 is turned on when the secondary battery 12 is not charged by the charger 14.

[0090]

As described above, according to the first to seventh aspects of the invention, each unit constituting the secondary battery is suppressed while suppressing the electric energy taken out from the secondary battery as energy loss. It is possible to properly equalize the charge states of the cells. Therefore, according to the present invention, the charging efficiency when charging each unit cell can be improved.

According to the eighth aspect of the invention, since the electric energy is distributed to each unit cell through the common transformer when the secondary battery is charged by the charger, the electric energy is not taken out from the secondary battery. It is possible to realize the equalization of the charge state of each unit cell. Therefore, according to the present invention, equalization of the unit cells of the secondary battery can be promoted.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a battery charging device that is a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the battery charging device of this embodiment.

FIG. 3 is a flowchart of a control routine executed to control a main switch and a conduction switch in the battery charger of this embodiment.

FIG. 4 is a flowchart of a control routine executed to control a main switch and a conduction switch in the battery charging device according to the second embodiment of the present invention.

FIG. 5 is a configuration diagram of a battery charging device that is a third embodiment of the present invention.

[Explanation of symbols]

10,200 Battery charger 12 Secondary battery 14 charger 16 Electric load 18 unit cells 20 Equalization circuit 22 common transformer 24 Main switch 26 Primary coil 28 Secondary coil 40 current path 44 diode 46 Bypass passage 48 continuity switch 50 Electronic Control Unit (ECU) 52 Charger voltage detection circuit 54 Unit cell voltage detection circuit 206 Electromagnetic relay 208 coil 210 Switch part

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tadashi Sato             F-de, 36-11 Shinbashi, Minato-ku, Tokyo             K.K Co., Ltd. (72) Inventor Katsuo Yamada             F-de, 36-11 Shinbashi, Minato-ku, Tokyo             K.K Co., Ltd. F term (reference) 5G003 AA01 BA03 CA11 CC02 DA07                       GB04 GC05                 5H030 AA01 AS20 BB01 DD08 FF43

Claims (8)

[Claims] 1. A secondary battery composed of a plurality of unit cells connected in series, and a common transformer connected to a primary coil via a predetermined current path with the secondary battery. An equalization circuit that distributes the electric energy supplied to the primary coil to each unit cell of the secondary battery by magnetically supplying the secondary coil of the common transformer corresponding to each unit cell of the secondary battery, A battery charging device comprising: a flow of current from the secondary battery to the primary side coil of the common transformer via the predetermined current path when the secondary battery is charged and permitted when not charged. A battery charger comprising a current flow path control means. 2. A control switch provided on the predetermined current path, wherein the current flow path control means cuts off the predetermined current path by using the control switch when charging the secondary battery, The battery charging device according to claim 1, wherein the battery charging device is made conductive during charging. 3. A diode provided in the predetermined current path and having a forward direction from a primary coil of the common transformer to the secondary battery, and a diode provided in the predetermined current path in parallel with the diode. And a control switch provided in the bypass passage, wherein the current flow path control means shuts off the bypass passage when the secondary battery is charged by using the control switch, and does not charge the secondary battery. The battery charging device according to claim 1, wherein the battery charging device is made conductive at times. 4. The control switch is a self-exciting switch that conducts the predetermined current path when the secondary battery is not charged, and interrupts the charging current by flowing a charging current when the secondary battery is charged. Alternatively, the battery charger according to item 3. 5. A secondary battery composed of a plurality of unit cells connected in series, and a common transformer connected to the secondary battery via a predetermined current path with the secondary battery are provided. An equalization circuit that distributes the electric energy supplied to the primary coil to each unit cell of the secondary battery by magnetically supplying the secondary coil of the common transformer corresponding to each unit cell of the secondary battery, In the battery charging device, the flow of current from the secondary battery to the primary side coil of the common transformer via the predetermined current path is caused by unit cell variation of the secondary battery exceeding a predetermined level. A battery charging device comprising a current flow path control means for prohibiting when there is not any and permitting when there is more than the predetermined amount. 6. A control switch provided on the predetermined current path, wherein the current distribution path control means uses the control switch to control the predetermined current path so that the variation between unit cells of the secondary battery is the same. 6. The battery charging device according to claim 5, wherein the battery charging device is shut off when the battery voltage has not been exceeded for a predetermined amount of time, and is turned on when the battery voltage has been exceeded for the predetermined amount. 7. A diode provided in the predetermined current path and having a forward direction from a primary coil of the common transformer to the secondary battery, and a diode provided in the predetermined current path in parallel with the diode. A bypass switch provided in the bypass passage, and a control switch provided in the bypass passage, wherein the current flow path control means uses the control switch in the bypass passage, and the variation between the unit cells of the secondary battery is the predetermined value. 6. The battery charging device according to claim 5, wherein the battery charging device is shut off when no occurrence of the above occurs, and is turned on when no occurrence occurs above the predetermined amount. 8. A charger connected to the secondary battery via the predetermined current path to charge the secondary battery, wherein the equalization circuit further comprises at least one of electric energy generated by the charger. 8. The unit is distributed to each unit cell of the secondary battery by supplying a part from the primary side coil of the common transformer to the secondary side coil by magnetic coupling. Battery charger.