JP2001268815A - Charge circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make uniform each voltage of secondary batteries that are connected in series, and to obtain a charge circuit for fully charging individually. SOLUTION: This charge circuit is provided with a transformer having a plurality of secondary coils for one primary coil, a switch, a first diode, and a secondary battery that are connected to the secondary coil in a loop, a full- charge detector for detecting the fully charged state of the secondary battery, and a control circuit for controlling the switching operation of the switch by inputting the detection signal of the full-charge detector. According to the configuration, a plurality of secondary batteries that are connected to the plurality of secondary coils are connected in series, and charge control is made individually according to the charged state of the plurality of secondary batteries, thus connecting the plurality of secondary batteries in series for preventing the overcharging of a battery where an output voltage value is increased, and preventing the battery from deteriorating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging circuit for uniformly charging a secondary battery, and more particularly to detecting a full charge of a plurality of secondary batteries connected in series during trickle charging to prevent overcharging. It relates to a charging circuit.

[0002]

2. Description of the Related Art Conventionally, in a charging circuit, when the voltage of one rechargeable battery is insufficient, it is common to connect the rechargeable batteries in series to boost the voltage. Such a usage method is widely applied to a communication backup application, a hybrid vehicle motor drive application, and the like.

When charging the above-mentioned series-connected secondary batteries, it is necessary to prevent each secondary battery from being overcharged and deteriorated. In addition, it is necessary to maximize the use efficiency by charging the battery until it is fully charged and using the secondary battery at the time of backup for use.

FIGS. 12 and 13 are diagrams showing a configuration example of a conventional charging circuit for a smart battery. These FIGS. 12 and 13 were published on December 11, 1998 (“Smart Batte
ry Selector Specification ”: Copyright by Intel Corporat
ion, Duracell Inc., Mitsubishi, Toshiba et al.) is a charge / discharge circuit having a mechanism (selector) for selecting a charge / discharge battery. As a method of charging a plurality of secondary batteries, for example, two A battery charging / discharging system for handling batteries has been proposed. The smart battery is intended for a notebook computer and has a power management mechanism.

The AC / DC converter shown in FIGS. 12 and 13 is a device for converting a commercial alternating current into a direct current. A smart battery charger is a device that converts a DC voltage of an AC / DC converter into a constant current or a constant voltage suitable for charging a smart battery. The smart battery selector is a device that switches a battery to be charged and discharged. The smart batteries A and B are secondary batteries each having an identifier. A power switch is a device that switches power supply from an AC / DC converter to a smart battery when a power failure occurs in AC commercial power supply. The system power supply is a device that converts a voltage supplied from an AC / DC converter or a smart battery into a voltage value having a required accuracy at a load, and the system host corresponds to the load. In addition, SMBus (System Management Bus)
Has a function of exchanging charging data and an identifier with a smart battery, and exchanging data with a system host (eg, CPU) and the like, and is used for power management.

FIG. 12 shows a configuration in which a smart battery A is charged by a charger before an AC commercial power failure, and a backup is provided by discharging the smart battery A when an AC power failure occurs. In the case of FIG. 12, the smart battery B does not participate in charge / discharge at all.

[0007] On the other hand, in FIG.
The backup operation at the time of commercial power outage, the smart battery B performs the charging operation before the AC commercial power outage, and the role of each battery is shared. As a matter of course, it is necessary to charge the smart battery A by the smart battery charger via the smart battery selector before designating the backup operation.

FIGS. 14 and 15 are diagrams for explaining an operation example of a conventional smart battery. As shown above, smart batteries assume that one secondary battery is used for both charging and discharging, or that one battery is used exclusively for charging and the other battery is used exclusively for discharging. It has been standardized. Therefore, a configuration for charging and discharging a plurality of batteries simultaneously in a smart battery is not shown. Further, a configuration in which a plurality of batteries are connected in series and charged simultaneously is not shown. This is apparent with reference to the operation explanatory diagrams of FIGS. 14 and 15. The smart battery A and the smart battery B are in a parallel relationship regardless of how the switch of the smart battery selector is switched. No circuit configuration for series connection is shown.

Next, FIG. 16 shows a circuit proposed to uniformly charge a serially connected secondary battery. FIG. 16 is a diagram showing a configuration example of a charging circuit using a conventional forward converter and a multi-winding transformer. This circuit is based on the journal [“ChargeEqualization for Series Co.”
nnected Battery Strings ”, IEEE Transaction onIndu
stry Applications, Vol.31, No.3 pp.562-568, May / Ju
ne1995.], in which a secondary battery is charged via a multi-winding transformer having one primary winding and a plurality of secondary windings. This circuit shows a case where three series-connected batteries are charged, and the number of secondary windings of the transformer is the same. Hereinafter, an operation example of the conventional charging circuit will be described.

In FIG. 16, a primary winding of a multi-winding transformer is excited by a twin-pole forward converter using two switching ICs. When the switching ICs Q1 and Q2 are turned on at the same time, the futoshi forward converter transmits power from the power supply Vs to the secondary winding of the transformer when the switching ICs Q1 and Q2 are turned on. And the current energy of the exciting inductance Lm is regenerated to the power supply Vs via the diodes D1 and D2. That is, when the above-mentioned Q1 and Q2 are simultaneously turned on, the power supply Vs is connected to the primary winding of the transformer (excitation inductance L
m), and this voltage is transmitted to the secondary winding side of the transformer. Therefore, the voltage vector coincides with the black circle direction indicated by the winding.

The secondary battery is charged through the diodes Da to Dc by the voltage transmitted to the secondary winding. The inductances L1 to L3 are diodes Da to reduce the current flowing due to the difference voltage between the secondary winding voltage and the secondary battery voltage.
It is connected in series with Dc. These diodes Da ~
Dc prevents current from flowing backward from the secondary battery to the secondary winding. Note that even after the above-mentioned Q1 and Q2 are turned off, the secondary battery is continuously charged until the current energy of L1 to L3 becomes zero due to the follow-up action of the inductances L1 to L3.

As described above, since each secondary battery is charged under the same conditions, if the characteristics of the secondary batteries are the same, if one secondary battery is fully charged, the other secondary batteries are fully charged. Further, if the number of turns of the secondary winding is the same, each secondary battery is characterized in that it is charged to the same (equal) voltage. However, in order to prevent overcharging, when one battery is fully charged, the charging of all batteries is suspended, or in order to make the charging power full, ignoring the detection of full charge and insufficient charging This has the problem of creating a dilemma that overcharging must be continued until the battery is exhausted.

FIG. 17 is a diagram showing a configuration example of a conventional charging circuit using a flyback converter and a multi-winding transformer. The circuit of FIG. 17 is another example of a circuit proposed to evenly charge a secondary battery connected in series, and is described in an international conference [“Balanced Charging of Series Connect”.
ed Battery Cells ”, Intelc'98, pp. 311-315], which charges a secondary battery via a multi-winding transformer having one primary winding and multiple secondary windings. .
The difference from the use of the transformer shown in FIG. 16 is that the transformer of FIG. 16 supplies a charging current to the secondary winding when a voltage is applied to the primary winding, whereas the transformer of FIG. When a voltage is applied, current is not supplied to the secondary winding, and current energy is stored in the exciting winding.

[0014] The current energy of the exciting winding is determined by comparing the secondary winding with the MOSFET during the period when no voltage is applied to the primary winding.
The secondary battery is charged via Qa to Qc. Although not shown in the presentation materials of the international conference, switches (Q1, Qa-Q
Since c) is an n-channel MOSFET, there is a parasitic diode in the direction as shown in FIG. This circuit shows a case where three series-connected batteries are charged, and the number of secondary windings of the transformer is the same. Hereinafter, an operation example of the present circuit will be described.

The primary winding of the multi-winding transformer is excited by a one-wheel flyback converter. The one-stone forward converter stores the energy of the power supply Vs as current in the exciting inductance Lm of the transformer when the MOSFET Q1 is turned on, and discharges the current energy of the exciting inductance Lm to the secondary winding side of the transformer when the MOSFET Q1 is turned off. That is, when the MOSFET Q1 is turned on, the power supply Vs is applied to both ends of the primary winding (excitation inductance Lm) of the transformer, and this voltage is transmitted to the secondary winding of the transformer.
In this case, the voltage vector matches the direction of the black circle displayed on the winding. However, this voltage reverse-biases the parasitic diodes (Qa to Qc) to
Since a to Qc) are also off, energy is not transmitted to the secondary winding side. Next, when the diode Q1 is turned off, the current energy stored in the exciting inductance Lm is transmitted to the secondary winding and charges the secondary battery.

As described above, as in the case of FIG. 16, each secondary battery is charged under the same conditions. Therefore, if the characteristics of the secondary batteries are completely the same, one secondary battery becomes fully charged. Other secondary batteries are also fully charged. Further, if the number of turns of the secondary winding is the same, each secondary battery is characterized in that it is charged to the same (equal) voltage. However, when one of the batteries is fully charged, there is a problem in that charging of all the batteries must be stopped or charging must be continued until overcharging ignoring detection of full charge.

FIG. 18 and FIG. 19 are diagrams showing a configuration example of a conventional charging circuit using a switched capacitor. FIGS. 18 and 19 show the connection of the capacitors Ce1 and Ce2 while switching the switches Ce1 to Sw3.
1, charging and discharging Ce2, and supplying the charged and discharged electric charges to the secondary battery to uniformly charge the voltage of the secondary battery. FIG. 18 shows a basic circuit configuration, and FIG. 19 shows an example of a case where the changeover switch is constituted by a MOSFET. FIG.
8 is a principle diagram. Actually, the capacitors Ce1 and C1
A resistor must be connected in series with e2, and if there is no resistor, there is a problem that the switches Sw1 to Sw3 are destroyed by a surge current.

According to the present circuit, if the values of the capacitors Ce1 and Ce2 are the same and the characteristics of the secondary batteries are uniform to some extent, each secondary battery can be charged evenly. Switched Capacitor system for Automati
c Series Battery Equalization ”, Apec'97, pp.848-8
54), JP-A-11-103534, JP-A-11-103535, etc. show variation circuits. However, since electric charges are successively transmitted between the capacitors, a large number of changeover switches are required, and it takes time to equalize the voltage of each secondary battery.

FIG. 20 is a diagram showing a configuration example of a conventional discharging circuit and a charging circuit using an auxiliary power supply. The charging circuit shown in FIG. 20 charges a plurality of secondary batteries connected in series by a main charging circuit and a main switch.
No. 13544. When one rechargeable battery is overcharged or undercharged, a set of switches (Sw1 to Sw) provided on each of the positive electrode and the negative electrode of the secondary battery is provided.
3) is switched to connect to a discharge circuit in case of overcharge and to connect to an auxiliary power supply in case of undercharge. This configuration can cope with insufficient charge and full charge of each secondary battery.

[0020]

However, in the above-mentioned prior art, when a plurality of batteries are undercharged or overcharged, a loop circuit is formed through each SW to cause an excessive current to flow, and Since a switch is required for each of the positive electrode and the negative electrode of each secondary battery, there are problems such as a large number of switches.

As a conventional charging circuit for uniformly charging a plurality of secondary batteries connected in series, a configuration using a transformer, a configuration of a switched capacitor system, and an auxiliary charging / discharging circuit for each secondary battery are used. The operation has been described for the three types of configurations. Neither configuration shows a configuration to cope with a case where a plurality of secondary batteries reach full charge, and therefore, as described above, suspends charging before the other secondary batteries reach full charge. Or the battery that has been fully charged is continuously overcharged.

The present invention has been made in view of the above-mentioned drawbacks of the conventional charging circuit, and has been made in consideration of the above-described drawbacks. It is intended to provide a circuit.

[0023]

In order to solve the above problems, a charging circuit according to the present invention comprises a transformer having a plurality of secondary windings for one primary winding, each of which is connected in series and both ends are connected. A switch, a first diode, and a secondary battery connected between terminals of the secondary winding and configured in a loop shape; a full charge detector for detecting a full charge state of the secondary battery; A control circuit for inputting a detection signal to control the opening / closing operation of the switch, wherein a plurality of secondary batteries connected to the plurality of secondary windings are connected in series, and each of the plurality of secondary batteries is charged. It is characterized in that charging is individually controlled according to the state.

In addition, the charging operation is individually controlled for each of the secondary batteries connected to the plurality of secondary windings, and the plurality of secondary batteries are connected in series to enable output of a laminated voltage. A main charging circuit is further connected to both ends of the plurality of rechargeable batteries that have been individually controlled to be connected in series,
It is preferable that batch charging can be performed in addition to individual charging of the secondary batteries connected in series and stacked.

Further, the above-mentioned full charge detection circuit inputs data including temperature and voltage measurement data of the secondary battery,
The charge state of the secondary battery is detected by detecting the voltage decay amount (−ΔV) or / and the temperature rise value per unit time (dT / dt) of the secondary battery, and the control circuit includes a PWM signal generation circuit, It is preferable to control the charge of the secondary battery by controlling the connection operation of the switch based on a control signal from the full charge detection circuit.

The control circuit receives a signal indicating whether or not each of the plurality of rechargeable batteries is in a full charge state from the full charge detection circuit. It is preferable that the charging circuit is opened, the charging of the secondary batteries is individually controlled, and the switch is a MOSFET.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a charging circuit according to the present invention will be described in detail with reference to the accompanying drawings. Figure 1
Referring to FIG. 11, one embodiment of the charging circuit of the present invention is shown.

(First Embodiment) FIG. 1 is a diagram of a multi-winding transformer charging circuit which is a first embodiment of the charging circuit of the present invention. FIG. 2 is a block diagram showing a more detailed configuration example of the full charge detection circuit and the control circuit in the first configuration example.

The charging circuit shown in FIG. 1 charges the DC / AC converter 10, the transformer 11, the rechargeable batteries 1 to 3 and the rechargeable batteries 1 to 3 connected to the DC power supply Vs. (Ra, Rb, Rc) configuring a circuit to perform
Diodes (Da1, Db1, Dc1), switches (S
a1, Sb1, Sc1), a backflow prevention diode (Da
2, Db2, Dc2), Sa1 to Sc1 control circuit 12,
It has a full charge detection circuit 13.

In the charging circuit of the embodiment shown in FIG. 1, the voltage of the DC power supply Vs is intermittently applied to the primary winding of the transformer 11 by the DC / AC converter 10. DC / AC converter 1
0 indicates that a one-stone forward type or a two-stone forward type can be used, and the voltage is transmitted to the secondary winding while the voltage is applied to the primary winding of the transformer 11, and the transformer 11
The transformer 11 is reset during a period in which no voltage is applied to the primary winding. The voltage applied to the secondary winding of the transformer 11 includes a parallel circuit of a resistor (Ra-Rc), a second diode (Da1-Dc1) and a switch (Sa1-Sc1), and a first diode (Da2-Dc2). ), The secondary batteries 1 to 3 are charged.

The switches (Sa1 to Sc1) are connected to the control circuit 12
Controls the operation. In this control, when the full charge detection circuit 13 that monitors the state of charge of each secondary battery detects full charge, the on / off ratio of a switch connected to the fully charged secondary battery is switched, The on / off ratio is reduced so that the average current is sufficient to supplement the self-discharge current. In FIG. 1, each of the secondary windings of the transformer 11 and the secondary battery are connected one-to-one, but the secondary windings are used in series or in parallel to reduce the voltage on the secondary winding side. It is also possible to increase the current or increase the current.

In FIG. 2 showing a configuration example of the full charge detection circuit 13 and the switch control circuit 12 of the present embodiment, the control circuit 12 includes an insulating circuit, a PWM signal generation circuit, and a differential amplifier circuit for each control line. It is configured to have. Further, the full charge detection circuit 13 includes an insulation circuit for receiving the temperature and voltage measurement data of each battery, and a −
It has a ΔV or dT / dt detection circuit and a full charge signal generation circuit. The insulation circuit in the full charge detection circuit is a circuit used for the purpose of separating the measurement target from the ground by a photocoupler, a transformer, a relay switch, and the like and reducing common mode noise. This insulating circuit can be omitted in a detection system that is unlikely to be connected to the ground, such as an insulated thermocouple.

A method of detecting full charge when the battery voltage drops by 5 to 20 mV from the peak value of each secondary battery voltage using the measured values of temperature and voltage (-ΔV detection), or a secondary battery The full charge of each secondary battery is detected by a method of detecting full charge when the temperature rise value per unit time (dT / dt detection) becomes a certain value or more. The full-charge detection signal is immediately sent from the full-charge signal generation circuit 13 to the switch control circuit 12.

The differential amplifier circuit of the control circuit 12 compares the internal reference signal with the full charge signal, and uses the full charge detection signal to
Decreases the on / off ratio of the signal generated by a PWM (pulse-width modulation) signal generation circuit (a circuit that changes the on / off ratio of a switch). The signal of the PWM signal generation circuit turns on / off the switch via the insulation circuit. As the PWM signal generating circuit and the differential amplifier circuit, those incorporated in a general-purpose DC / DC controller IC (for example, “Switching Power Supply Handbook”, Nikkan Kogyo Shimbun, PP.501-512, 1993) can be used. is there. Also, if a pulse-frequency modulation (PFM) control circuit is used instead of the PWM signal generation circuit, the pulse interval can be varied while keeping the pulse width constant, so that the same effect of changing the on / off ratio is obtained. be able to. Furthermore, if a pulse-number modulation (PNM) control circuit is used instead of the PWM control circuit and the number of pulses is reduced after full charge detection, the average charge current before and after full charge can be changed. Will be possible.

FIG. 3 shows an example of a configuration in which a MOSFET for a transformer secondary-side switch is used, and FIG. 4 shows an example of a configuration in which a MOSFET is replaced. When a MOSFET is used as the switches (Sa1 to Sc1) in FIG.
As shown in (1), the parasitic diode plays a role similar to that of the second diode. Therefore, the second diode can be omitted, and the circuit can be simplified.

FIG. 5, FIG. 6, and FIG. 7 are diagrams for explaining an operation example in the case of using a method of limiting the supply current of the secondary battery by a pulse width, that is, so-called PWM control. FIGS. 5, 6, and 7 schematically show ON / OFF signals of the switches Sa1 to Sc1 when the PWM control circuit is used. FIG. 5 shows a case before the three secondary batteries reach full charge, and signals having the same ON / OFF width are applied to the switches Sa1 to Sc1. With this signal, a charging current is supplied to the secondary battery through the secondary winding of the transformer shown in FIG. 1 to perform pulse charging. Next, FIG. 6 shows a state in which the secondary battery 1 has reached full charge, and the secondary batteries 2 and 3 have not reached full charge. In this case, a signal with a narrow ON width is supplied to the switch Sa1 to supply an average current sufficient to supplement the self-discharge current. Finally, FIG. 7 shows the signal form of the switch when the secondary battery 1 is already fully charged and then the secondary battery 2 is fully charged. The ON signal widths of the switches Sa1 and Sb1 for supplying the charging current to the fully charged secondary batteries 1 and 2 are reduced, and a signal having a large ON width is continuously applied to Sc1 until the battery is fully charged.

Although not shown in the figure, since the secondary battery 3 eventually reaches full charge and an ON signal having a narrow pulse width is applied to the switches Sa1 to Sc1, the average of the charging current of each secondary battery is obtained. The value becomes a very small value. After all the secondary batteries have reached full charge in this way, each secondary battery is charged with a small average current (trickle charging), so that there is no problem of overcharging. Furthermore, the average charging current during the trickle charging period is
Since it is approximately proportional to (the induction voltage of the secondary winding of the transformer minus the voltage of the secondary battery) divided by the resistances (Ra to Rc), a large charging current is supplied to the low-voltage secondary battery. Further, since a small charging current is supplied to the secondary battery having a high voltage, the voltage of each secondary battery becomes gradually equal.

FIGS. 8 and 9 are diagrams for explaining an operation example in the case of using a method of limiting the supply current of the secondary battery by the number of pulses, that is, so-called PNM control. FIG. 8 shows the form of the on / off signal of the switches Sa1 to Sc1 before the operation of the full charge detection circuit. FIG. 9 shows a switch S
It shows the form of the on / off signal of the switches Sa1 to Sc1 after the detection of the full charge of a1.

The charging circuit according to the above embodiment is configured as a charging circuit that connects a plurality of secondary batteries in series and performs a charging operation via a transformer having one primary winding and a plurality of secondary windings. You. In the present charging circuit, between the positive electrode and the negative electrode of each secondary battery, at least one of the secondary windings of the transformer, the resistance, and the first that is forward-biased by the induced voltage of the secondary winding of the transformer. A circuit in which a diode, a second diode reverse-biased by the induced voltage of the secondary winding, and a parallel connection circuit of a charging switch connected in parallel to the second diode are connected in series. Furthermore, a charge state monitoring circuit for each secondary battery is provided, and this charge state monitoring circuit has a function of detecting full charge of each secondary battery and a function of controlling a charging switch.

In the above arrangement, the switch connected in parallel to the second diode may be a MOSFET, and the second diode may be a parasitic diode of this MOSFET.
A main charging circuit in which a main charging circuit and a main switch are connected in series; and the main charging circuit is connected to both ends of a plurality of rechargeable batteries connected in series to fully charge at least one rechargeable battery. A function to turn on / off the charging switch and perform charging with the main switch until is detected,
After the full charge of at least one secondary battery is detected, a function is provided in which the main switch is turned off, the charging switch is operated, and the secondary battery is charged via the secondary winding of the transformer. .

With the charging circuit having the above structure, the first diode prevents current from flowing from the secondary battery to the secondary winding of the transformer, and the switch connected in parallel with the second diode and the second diode Performs the function of converting the charging current of the secondary battery into a pulse. The resistance holds the peak value of the pulse current that flows when the switch connected in parallel to the second diode is turned on, approximately equal to the value (the induction voltage of the secondary winding of the transformer minus the voltage of the secondary battery) divided by the resistance. I do.
The switch connected in parallel to the second diode has a constant ON / OFF cycle depending on the state of charge of the secondary battery and changes the ON width, or a constant ON width and changes the ON / OFF cycle. Adjust the charging current of the secondary battery. In particular, the average current of a fully charged secondary battery is maintained to a level that compensates for self-discharge to avoid overcharging. The primary winding of the transformer is excited by a DC / AC conversion unit of a single-stone forward type or a double-stone forward type.

(Second Embodiment) FIG. 10 is a diagram showing a multi-winding transformer charging circuit which is a second configuration example of the present embodiment. In FIG. 10, the main charging circuit including the main switch Ss and the main charging circuit 21 is connected to the electrodes at both ends of the series-connected secondary batteries 1 to 3 shown in FIG. The main charging circuit performs rapid charging in a state where all the secondary batteries 1 to 3 have not reached full charge, and when one of the secondary batteries is detected to be fully charged, immediately turns off the switch Ss. At least one of the secondary windings of the winding transformer, resistors (Ra, Rb, Rc), and switches (Sa1,
Sb1, Sc1) and first diodes (Da2, Db)
2, Dc2) to charge each of the secondary batteries 1 to 3.

FIG. 11 shows a control circuit 22 and a full charge detection circuit 23 according to the second embodiment of the present invention. The control circuit switches between the main charging circuit side and the multi-winding transformer side charging circuit in FIG. An example of the configuration is shown. FIG.
FIG. 1 shows an example in which the main switch Ss also performs pulse control.

In FIG. 11, which shows a configuration example of the full charge detection circuit 23 and the switch control circuit 22 of the second embodiment, the control circuit 2 for the switches (Sa1, Sb1, Sc1)
2 is an insulating circuit, an AND circuit, and a PWM for each control line.
The circuit includes a signal generation circuit, a differential amplifier circuit, a logic wheel circuit, a reference voltage generation circuit for controlling a main switch, a PWM signal generation circuit, an inverter circuit, and a logical product circuit. The full charge detection circuit 23 has an insulation circuit for receiving temperature and voltage measurement data of each battery, a -ΔV or dT / dt detection circuit for detecting voltage fluctuation of the battery, and a full charge signal generation circuit. It is composed. The insulation circuit in the full charge detection circuit is a circuit used for the purpose of separating the measurement target from the ground by a photocoupler, a transformer, a relay switch, and the like and reducing common mode noise, as in the first embodiment. .

First, when all of the secondary batteries 1 to 3 have not reached full charge, the full charge signal generation circuit provided for each of the secondary batteries sends out all low level signals. . Since the inputs of the OR circuit provided in the switch control circuit are all low level signals, they output low level signals. Therefore, the AND circuit for Sa1 to Sc1 does not output a signal from the PWM signal generation circuit. On the other hand, on the main switch Ss side, the signal of the OR circuit is high by the inverter circuit.
Since the signal is converted to a level, the PWM signal is output for driving Ss.

Next, when one secondary battery reaches full charge, a high level signal is generated from the full charge generation circuit.
The output of the OR circuit becomes High level. Therefore, Sa1
The PWM signal for driving .about.Sc1 is output through the AND circuit, and the driving signal for Ss is cut off.

According to the second embodiment, when a large-capacity charging power source is required to rapidly charge a series-connected secondary battery, the series-connected battery is first replaced with a large-capacity charging power source. When full charge is detected even in one of the secondary batteries connected in series, a large-capacity charging power source is disconnected and the secondary batteries are individually charged. Therefore, charging efficiency can be further improved.

With such a configuration, the state-of-charge detection circuit (actually, a full-charge detection circuit for each secondary battery and control for turning on / off a switch connected in parallel to the second diode) Circuit) detects the full charge of each secondary battery, and controls the on / off ratio of the switch to individually change the charge current of the secondary battery.

In addition, when the rapid charging is first performed, the main charging circuit of a large capacity is used, and when at least one battery is fully charged, the main charging circuit is disconnected. By performing the supplementary charging by operating the individual charging circuit, it is possible to prevent each secondary battery from being overcharged.

[0050]

As is clear from the above description, in the charging circuit of the present invention, a charging circuit is formed in a loop shape on each of a plurality of secondary windings of a transformer, and a plurality of secondary batteries are connected in series. Then, the charge is individually controlled in accordance with the state of charge of the secondary battery. Therefore, when full charge is detected even in one of the secondary batteries connected in series, the fully charged battery is trickle-charged, and all secondary batteries that are already fully charged are not burdened. The secondary battery can be fully charged.

[Brief description of the drawings]

FIG. 1 shows a charging circuit according to an embodiment of the present invention, and is a multi-winding transformer charging circuit diagram which is a first configuration example.

FIG. 2 is a block diagram illustrating a configuration example of a full charge detection circuit and a control circuit in a first configuration example.

FIG. 3 shows a configuration example when a MOSFET for a transformer secondary-side switch is used.

FIG. 4 is a diagram illustrating a configuration example of replacement by a MOS FET;

FIG. 5 is a first diagram illustrating an operation example of a method (PWM control) of limiting a supply current of a secondary battery by a pulse width.

FIG. 6 is a second diagram illustrating an operation example of a method (PWM control) of limiting a supply current of a secondary battery by a pulse width.

FIG. 7 is a third diagram illustrating an operation example of a method (PWM control) of limiting a supply current of a secondary battery by a pulse width.

FIG. 8 is a first diagram illustrating an operation example of a method (PNM control) of limiting the supply current of the secondary battery by the number of pulses.

FIG. 9 is a second diagram for describing an operation example of a method (PNM control) of limiting the supply current of the secondary battery by the number of pulses.

FIG. 10 is a diagram showing a second configuration example of the present invention and showing a multi-winding transformer charging circuit.

FIG. 11 is a diagram showing a full charge detection circuit and a control circuit in the first configuration example of the present invention.

FIG. 12 shows an example in which a smart battery A in the prior art is selected for charging / discharging.

FIG. 13 shows a conventional smart battery A for discharging,
An example in which B is selected for charging is shown.

FIG. 14 shows a connection diagram when a smart battery A in the prior art is selected for charging / discharging.

FIG. 15 shows a conventional smart battery A for discharging,
FIG. 4 shows a connection diagram when B is selected for charging.

FIG. 16 shows a charging circuit diagram using a conventional multi-winding transformer.

FIG. 17 shows a charging circuit diagram using a conventional multi-winding transformer.

FIG. 18 is a diagram illustrating the operation principle of a conventional charging circuit.

FIG. 19 shows a switch (SW) applied to a conventional charging circuit.
It is a figure which shows the example of 1) specific structure.

FIG. 20 shows a conventional charging circuit (discharging circuit and auxiliary power supply)
FIG. 3 is a diagram showing an example of the configuration.

[Explanation of symbols]

Reference Signs List 10 DC / AC converter 11 Transformer 12 Control circuit 13 Full charge detection circuit Da1, Db1, Dc1, Da2, Db2, Dc2 Diode Ra, Rb, Rc Resistor Sa1, Sb1, Sc1 Switch Vs DC power supply

Claims (7)

[Claims] 1. A transformer having a plurality of secondary windings for one primary winding, a switch each connected in series and having both ends connected between terminals of the secondary winding and configured in a loop shape, A first diode and a secondary battery; a full-charge detector for detecting a full charge state of the secondary battery; a control circuit for receiving a detection signal of the full-charge detector and controlling opening and closing operations of the switch; Wherein the plurality of secondary batteries connected to the plurality of secondary windings are connected in series, and charge control is performed individually according to the state of charge of each of the plurality of secondary batteries. Charging circuit. 2. The charging operation is individually controlled for each of the secondary batteries connected to the plurality of secondary windings, and the plurality of secondary batteries are connected in series to enable output of a laminated voltage. The charging circuit according to claim 1, wherein: 3. A plurality of secondary batteries, each of which has been individually controlled to be charged, further comprising a main charging circuit connected to both ends of the secondary batteries connected in series, and connected in series to the stacked secondary batteries. The charging circuit according to claim 1, wherein a batch charging is enabled in addition to the individual charging. 4. The full charge detection circuit inputs data including temperature and voltage measurement data of the secondary battery, and a voltage attenuation (−ΔV) or / and a temperature rise per unit time of the secondary battery. 4. The charging circuit according to claim 1, wherein the charging state of the secondary battery is detected by detecting a value (dT / dt). 5. The control circuit includes a PWM signal generation circuit,
A PFM control circuit or a PNM control circuit, and controlling the connection operation of the switch based on a control signal from the full charge detection circuit to control charging of the secondary battery. The charging circuit according to any one of claims 1 to 4, wherein 6. The control circuit receives a signal indicating whether or not each of the plurality of rechargeable batteries is in a full charge state from the full charge detection circuit, and when any one of the plurality of secondary batteries receives a full charge signal, The charging circuit according to any one of claims 3 to 5, wherein the main charging circuit is opened to control charging of the secondary batteries individually. 7. The charging circuit according to claim 1, wherein the switch is a MOS FET.