JP2011067041A - Charger and charging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charger and a charging system, reducing the possibility of excessive increase in an output voltage when a charge current is cut off on a battery pack side, in the charger which charges a battery pack in which a full charge of a secondary battery is determined on the battery pack side to cut off the charge current. <P>SOLUTION: The charger is equipped with: a power supply part 11 which outputs a charge voltage; a current control part 14 which controls the charge voltage of the power supply part 11 so that the charge current becomes equal to a set current value and performs constant current charge; a limit voltage value setting part 16 which forms a limit voltage value Vrv by increasing a voltage value signal Vsen detected by a voltage detection part 13 only by a set voltage value Vm and delaying it only by a delay time d; and a comparator 15 which limits the charge voltage of the power supply part 11 by the limit voltage value Vrv. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a charging device and a charging system for charging a battery pack including a secondary battery.

  A charging device for charging a battery pack using a secondary battery generally performs charging by a CCCV (Constant Current Constant Voltage) charging method. In the CCCV charging method, charging starts with constant current charging, and when the terminal voltage of the secondary battery reaches the set voltage set in advance to the fully charged voltage of the secondary battery, it shifts to constant voltage charging and the current droops. As a result, full charge is detected and charge output is stopped.

  In addition, when performing CCCV charging, the setting voltage for determining the transition from constant current charging to constant voltage charging is the circuit voltage generated by the wiring resistance from the voltage output unit to the battery pack, the contact resistance of the connection terminal, etc. A method of reducing the charging time by executing constant current charging to the full charge voltage inherent to the secondary battery by setting the voltage value obtained by adding the drop to the full charge voltage has been devised (for example, see Patent Document 1). ).

JP-A-8-195225

  By the way, there are various uses for battery packs, and the required voltages are often different from each other, and various battery packs having a full charge voltage required for each are required. On the other hand, the above-described conventional charging device performs constant current charging until the terminal voltage of the secondary battery reaches a preset full charge voltage or a value obtained by adding the voltage drop of the circuit to the full charge voltage. Since it is what is executed, it is necessary to use a charging device according to the full charge voltage of the battery pack.

  If the full charge voltage set for the charging device and the full charge voltage of the battery pack are different, the secondary battery will be overcharged, causing deterioration and reduced safety, or charging until the secondary battery is fully charged. This is because it cannot be done.

  Therefore, if you own multiple battery packs with different full charge voltages, you need multiple chargers that can charge each battery pack, requiring a large installation space and increasing the user's cost burden. There is an inconvenience. Therefore, there is a need in the market for a charging device that can charge various battery packs regardless of the difference in full charge voltage.

  Therefore, if a switching element that cuts off the charging current is provided on the battery pack side, and the charging current is cut off by determining that the secondary battery is fully charged on the battery pack side, a single charging device can be used for full charging. It is considered that various battery packs having different voltages can be charged.

  However, if the battery pack side cuts off the charging current during constant current charging that supplies a constant charging current, the charging device suddenly increases the output voltage to maintain the constant charging current, and the charging device outputs Raises the output voltage to the maximum possible voltage. Therefore, regardless of the full charge voltage of the battery pack, the breakdown voltage of the switching element provided on the battery pack side needs to be equal to or higher than the maximum output voltage of the charging device. A switching element with a high breakdown voltage is larger in size and cost than a switching element with a low breakdown voltage, leading to inconvenience that the battery pack is increased in size and cost.

  An object of the present invention is to charge a battery pack that determines the full charge of a secondary battery on the battery pack side and cuts off the charging current.When the charging current is cut off on the battery pack side, It is an object of the present invention to provide a charging device and a charging system that can reduce the possibility of an excessive increase in output voltage.

  The charging device according to the present invention includes a connection terminal for connecting to a battery pack including a secondary battery, and a power source for outputting a charging voltage for charging the secondary battery to the battery pack via the connection terminal. A current detection unit that detects a current value flowing from the power supply unit to the secondary battery via the connection terminal, a voltage detection unit that detects a value of the charging voltage as a charging voltage value, and the current detection unit A current control unit for performing constant current charging by controlling a charging voltage output from the power supply unit so that a current value detected by the power supply unit becomes a preset set current value, and the voltage detection unit A limit for generating a limit voltage value indicating a limit voltage to limit the charge voltage by increasing the charge voltage value to be set by a preset set voltage value and delaying the charge voltage value by a preset delay time Comprising a pressure value setting unit, the charging voltage in the constant current charging with the current control unit, and a voltage limiting unit for limiting the limit voltage value generated by the limit voltage value setting unit.

  According to this configuration, when charging the battery pack which determines that the secondary battery is fully charged and cuts off the charging current on the battery pack side, the current control unit supplies the secondary battery to the secondary battery. The charging voltage is controlled so that the constant current charging is performed such that the current value to be set becomes the set current value. Then, the charging voltage gradually increases as the charging of the secondary battery proceeds. Then, the charging voltage value detected by the voltage detecting unit should be increased by the preset voltage value and delayed by the preset delay time by the limit voltage value setting unit to limit the charging voltage. Limit voltage values indicating the limit voltage are sequentially generated.

  Here, when the secondary battery is fully charged and the charging current is cut off on the battery pack side, the current control unit increases the charging voltage to maintain the charging current at the set current value. However, the charging voltage is limited by the limit voltage value by the voltage limiting unit. The limit voltage value is a value obtained by increasing the charge voltage value by the set voltage value and delaying the charge voltage value by a preset delay time. Therefore, the charging voltage is limited by the voltage value obtained by adding the set voltage value to the voltage before the delay time elapses, that is, before the charging voltage rises due to the interruption of the charging current. Therefore, the charging voltage does not increase excessively. Therefore, when charging a battery pack that determines the full charge of the secondary battery on the battery pack side and cuts off the charging current, the charging voltage is excessively exceeded when the charging current is cut off on the battery pack side. The risk of rising can be reduced.

  In addition, when the charge voltage value detected by the voltage detection unit exceeds the limit voltage value generated by the limit voltage value setting unit, a stop control unit that stops the output of the charge voltage by the power source unit is further provided. Is preferred.

  According to this configuration, when the charge voltage value exceeds the limit voltage value generated by the limit voltage value setting unit, the secondary battery is fully charged and the charge current is cut off on the battery pack side. The current control unit is considered to have increased the charging voltage to maintain the charging current at the set current value. Therefore, the stop control unit stops the output of the charging voltage by the power supply unit when the charging voltage value exceeds the limiting voltage value generated by the limiting voltage value setting unit, so that the secondary battery becomes fully charged. Charging can be terminated.

  In addition, the charging voltage value detected by the voltage detection unit exceeds the limit voltage value generated by the limit voltage value setting unit, and the current value detected by the current detection unit is less than the set current value Further, a stop control unit that stops the output of the charging voltage by the power source unit may be further provided.

  As described above, when the charging voltage value exceeds the limit voltage value, it is basically considered that the secondary battery is fully charged and the charging current is cut off on the battery pack side. However, the charge voltage value may exceed the limit voltage value due to noise. On the other hand, when the charging current is interrupted on the battery pack side, the current value detected by the current detection unit falls below the set current value. Therefore, the stop control unit has a charge voltage value detected by the voltage detection unit exceeding a limit voltage value generated by the limit voltage value setting unit, and a current value detected by the current detection unit is less than the set current value. In this case, the influence of noise can be reduced by stopping the output of the charging voltage by the power supply unit.

  Further, the set voltage value is the terminal voltage of the secondary battery when the secondary battery is charged during the delay time by constant current charging with the current of the set current value in a state where the SOC is 0%. It is preferable that the value is set larger than the increase value.

  The amount of increase in the charging voltage per unit time when the secondary battery is charged with a constant current is greatest when the SOC is 0%. Therefore, when the SOC of the secondary battery is 0%, the set voltage value is set to be higher than the increase value of the terminal voltage of the secondary battery when the secondary battery is charged during the delay time by constant current charging with the current of the set current value. If the value is set to a large value, the charging voltage that is increased due to constant current charging of the secondary battery does not exceed the limit voltage.

  As a result, even though the charging current is not cut off on the battery pack side, and thus the constant current charging can be performed, the charging voltage that has risen due to the constant current charging of the secondary battery is the limit voltage. This reduces the risk that the charging voltage will be limited to the limiting voltage and the charging current will decrease.

  In addition, the delay time is determined so that the current control unit increases the charging voltage by the set voltage represented by the set voltage by the power supply unit in order to increase the current value detected by the current detection unit. It is preferable that the time is set longer than the response time.

  If the delay time is shorter than the response time, the charging current is cut off on the battery pack side, the charging voltage is increased by the current control unit, and when the set voltage is increased, the charging current is cut off. From time to time, a time longer than the delay time has elapsed. Then, the limit voltage value is a value obtained by adding the set voltage value to the charge voltage value after the charge current is cut off on the battery pack side. In this case, the charging voltage value after the charging current is cut off has already started to rise by the current feedback of the current control unit, and is higher than the voltage before the charging current cut off. In this case, the limit voltage becomes higher than the voltage value obtained by adding the set voltage value to the voltage before the increase in the charging voltage due to the interruption of the charging current, so that an excessive increase in the charging voltage can be suppressed. Certainty is reduced.

  However, according to this configuration, since the delay time is longer than the response time, the limit voltage value is added by the set voltage value to the voltage before the charging voltage rises due to the interruption of the charging current. Since the charging voltage is limited by this limit voltage value, the certainty that the excessive increase of the charging voltage can be suppressed increases.

  The limit voltage value setting unit is preset with an addition unit that adds the charging voltage value detected by the voltage detection unit and the set voltage value, and an addition value added by the addition unit. It is preferable to include a delay unit that delays the delay time based on a time constant and outputs the delayed voltage value to the voltage limiting unit.

  According to this configuration, the charging voltage value and the set voltage value are added by the adding unit, and the added value is delayed by the delay unit based on a preset time constant, and the limit is set. The voltage value is output to the voltage limiter.

  The current control unit outputs a request signal for reducing the charging voltage to the power supply unit when a current value detected by the current detection unit exceeds the set current value, and the current detection unit When a current value detected by the power supply unit is less than the set current value, a request signal for increasing the charging voltage is output to the power supply unit, whereby the output current value by the power supply unit is set to the set current value. The voltage limiting unit outputs a request signal to the power supply unit to reduce the charging voltage when the charging voltage value detected by the voltage detecting unit exceeds the limiting voltage value. A logical sum of a request signal for reducing the charging voltage from the current control unit and a request signal for reducing the charging voltage from the voltage control unit. When a request signal for reducing the charging voltage is output from any one of the limiting units, a control signal for decreasing the charging voltage is output to the power supply unit, and the current control unit and the voltage When a request signal for decreasing the charging voltage is not output from any of the limiting units, it is preferable to further include an OR circuit that outputs a control signal for increasing the charging voltage to the power supply unit.

  According to this configuration, when the current value detected by the current detection unit exceeds the set current value, the current control unit outputs a request signal for reducing the charging voltage to the power supply unit, and is detected by the current detection unit. When the current value to be supplied is less than the set current value, a request signal for increasing the charging voltage is output to the power supply unit, so that the current value detected by the current detection unit is fed back and output by the power supply unit. The current value is controlled to the set current value.

  Then, when the charging voltage value detected by the voltage detection unit exceeds the limiting voltage value, the voltage limiting unit outputs a request signal for reducing the charging voltage to the power supply unit. Value is limited. Further, the logical sum circuit logically sums the request signal for reducing the charging voltage from the current control unit and the request signal for decreasing the charging voltage from the voltage control unit, and the current control unit and the voltage limiter. When a request signal for decreasing the charging voltage is output from any one of the units, a control signal for decreasing the charging voltage is output to the power supply unit.

  As a result, the charging current is cut off on the battery pack side, and charging is performed even when a request signal for increasing the charging voltage is output by the current control unit in order to maintain the charging current of the set current value. When the voltage signal exceeds the limit voltage value and a request signal for reducing the charging voltage is output from the voltage limit unit, the request signal from the voltage limit unit is prioritized by a simple OR operation, A control signal for reducing the charging voltage is output to the power supply unit, and the charging voltage is limited.

  In this case, since switching from the control signal for increasing the charging voltage to the control signal for decreasing the charging voltage is performed by a simple OR operation, the charging voltage value exceeds the limiting voltage value and the charging voltage is supplied from the voltage limiting unit. When a request signal for lowering the voltage is output, the delay time required for switching the control signal is shortened, and as a result, it is easy to quickly limit the charging voltage.

  The charging system according to the present invention includes the above-described charging device and the battery pack, and the battery pack includes a pack-side connection terminal connected to the connection terminal, the pack-side connection terminal, and the secondary battery. A switching element that opens and closes a connection with a battery, and determines whether or not the secondary battery is fully charged, and when the secondary battery is fully charged, a full charge determination that turns off the switching element A part.

  According to this configuration, when the secondary battery is fully charged, the full charge determination unit on the battery pack side determines that the secondary battery is fully charged, turns off the switching element, and interrupts the charging current. . At this time, a possibility that a charging voltage will rise excessively by the above-mentioned charging device is reduced.

  In addition, it is preferable that a plurality of the battery packs are provided, a plurality of connection terminals for connecting to each of the battery packs are provided, and a changeover switch that switches connection between the power supply unit and the plurality of connection terminals is further provided.

  According to this configuration, even when the full charge voltages of the battery packs are different from each other, it is possible to charge each battery pack by switching the changeover switch.

  The charging device and the charging system having such a configuration can reduce the possibility that the charging voltage will rise excessively when the charging current is interrupted on the battery pack side.

It is a block diagram which shows an example of a structure of the charging system using the charging device which concerns on one Embodiment of this invention. It is explanatory drawing for demonstrating an example of operation | movement of the charging system shown in FIG. It is a block diagram which shows the modification of the charging system shown in FIG.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted. FIG. 1 is a block diagram illustrating an example of a configuration of a charging system using a charging device according to an embodiment of the present invention.

  The charging system 1 shown in FIG. 1 is configured by connecting a charging device 10 and a battery pack 20. The charging device 10 includes a connection terminal 101, 102, 103, 104, a power supply unit 11, a current detection unit 12, a voltage detection unit 13, a current control unit 14, a comparator 15 (voltage limiting unit), a limited voltage value setting unit 16, and a comparator. 17 (stop control unit) and an OR circuit 18 are provided.

  The current control unit 14 includes a comparator 141 and a current setting reference voltage source 142. The limit voltage value setting unit 16 includes an operational amplifier 161, resistors R1, R2, R3, and R4, a capacitor C1, and a set voltage source 162. The OR circuit 18 includes diodes D1 and D2 and a pull-down resistor R5. For example, a commercial power supply AC is connected to the power supply unit 11 via the connection terminals 103 and 104.

  The battery pack 20 includes a secondary battery 21, a switching element 22, a full charge determination unit 23, and pack side connection terminals 201 and 202. A series circuit of the switching element 22 and the secondary battery 21 is connected between the pack side connection terminals 201 and 202.

  The switching element 22 is a switching element such as an FET (Field Effect Transistor) or a relay switch. As the secondary battery 21, various secondary batteries such as a lithium ion secondary battery and a nickel hydride secondary battery are used. The secondary battery 21 may be composed of one cell, or may be an assembled battery composed of a plurality of cells connected in series, parallel, or a combination of parallel and series.

  The full charge determination unit 23 determines whether or not the secondary battery 21 is fully charged. When the secondary battery 21 is fully charged, the switching element 22 is turned off to charge the secondary battery 21 with a charging current. Cut off. The full charge determination unit 23 detects, for example, the terminal voltage of the secondary battery 21, and when the terminal voltage becomes equal to or higher than a full charge voltage set in advance as a voltage when the secondary battery 21 is fully charged. Then, it is determined that the secondary battery 21 is fully charged.

  Alternatively, the full charge determination unit 23 calculates the stored charge amount of the secondary battery 21 by, for example, integrating charge / discharge current values flowing through the secondary battery 21, and the stored charge amount is the full charge capacity of the secondary battery 21. When it becomes above, it may determine with the secondary battery 21 having been fully charged, and may determine full charge with the other method.

  When the battery pack 20 is attached to the charging apparatus 10, the connection terminal 101 and the pack-side connection terminal 201, and the connection terminal 102 and the pack-side connection terminal 202 are connected to each other. The connection terminal 102 is connected to the circuit ground in the charging device 10.

  The power supply unit 11 is configured using, for example, a switching power supply circuit. And the power supply part 11 converts the alternating voltage supplied from commercial power supply AC via the connection terminals 103 and 104, for example into a direct voltage, and produces | generates the charging voltage Vout of the secondary battery 21. FIG. The power supply unit 11 supplies the charging voltage Vout to the secondary battery 21 via the current detection unit 12, the connection terminal 101, the pack side connection terminal 201, and the switching element 22.

  The power supply unit 11 changes the charging voltage Vout according to the control signal OP output from the OR circuit 18. Further, the power supply unit 11 stops the charging of the secondary battery 21 according to the charging stop signal STOP output from the comparator 17 and sets the charging voltage Vout to zero.

  In the OR circuit 18, the anode of the diode D 1 is connected to the output terminal of the comparator 15, and the anode of the diode D 2 is connected to the output terminal of the comparator 141. The cathodes of the diodes D1 and D2 are connected to each other, further pulled down by the resistor R5, and connected to the power supply unit 11.

  As a result, the request signal Vop output from the comparator 15 and the request signal Iop output from the comparator 141 are logically summed and output to the power supply unit 11 as the control signal OP.

  The current detection unit 12 is configured by using, for example, a shunt resistor, a current transformer, and the like, and a current value signal Isen indicating the output current Iout flowing from the power supply unit 11 to the secondary battery 21 via the connection terminal 101 at a voltage level. Is output to the + terminal of the comparator 141.

  The voltage detection unit 13 is configured by using, for example, a voltage dividing resistor, an amplifier, and the like, and a voltage value signal Vsen (charging voltage value) indicating the charging voltage Vout output from the power supply unit 11 at a voltage level is supplied to the comparator 15. Output to the + terminal and the limit voltage value setting unit 16.

  The current control unit 14 is configured such that the current value signal Isen is input to the + terminal of the comparator 141 and the current setting reference voltage Vir output from the current setting reference voltage source 142 is input to the − terminal of the comparator 141. Yes. The current setting reference voltage Vir is set to a voltage value representing a set current value Icc for constant current charging.

  Further, the anode of the diode D <b> 2 is connected to the output terminal of the comparator 141, and the cathode of the diode D <b> 2 is connected to the power supply unit 11.

  As a result, when the output current Iout exceeds the set current value Icc, the current control unit 14 outputs the request signal Iop at a high level. Then, a high-level control signal OP is output to the power supply unit 11 via the diode D2, and the power supply unit 11 decreases the charging voltage Vout and decreases the output current Iout.

  Further, when the output current Iout becomes equal to or less than the set current value Icc, the current control unit 14 outputs the request signal Iop at a low level. Then, a low-level control signal OP is output to the power supply unit 11 via the diode D2, the charge voltage Vout is increased by the power supply unit 11, and the output current Iout is increased. Thus, by performing feedback control based on the output current Iout by the current control unit 14, the output current Iout of the power supply unit 11 is controlled to be constant at the set current value Icc, and constant current charging is performed. It is like that.

  The limit voltage value setting unit 16 limits the charging voltage Vout by increasing the voltage value signal Vsen output from the voltage detection unit 13 by the set reference voltage Vmin and delaying the voltage value signal Vsen by a preset delay time d. A limit voltage value signal Vr indicating the power limit voltage value Vrv is generated and output to the negative terminal of the comparator 15.

  The limit voltage value setting unit 16 is configured as follows. First, the set voltage source 162 outputs the set reference voltage Vmin to the + terminal of the operational amplifier 161 via the resistor R2. The set reference voltage Vmin indicates the set voltage value Vm depending on the voltage level.

  The voltage value signal Vsen output from the voltage detection unit 13 is input to the + terminal of the operational amplifier 161 via the resistor R3.

  The negative terminal of the operational amplifier 161 is connected to the circuit ground via the resistor R1, and the resistor R4 is connected between the output terminal and the negative terminal of the operational amplifier 161. Thus, an adder circuit (adder) is configured to add the voltage of the voltage value signal Vsen and the set reference voltage Vmin to generate a limit voltage value signal Vr that represents the limit voltage value Vrv by a voltage level.

  Further, a capacitor C1 is connected between the output terminal and the negative terminal of the operational amplifier 161. Thereby, the rise of the limit voltage value signal Vr is delayed, and the delay time d required to increase the limit voltage value signal Vr by the set reference voltage Vmin is set according to the time constant obtained by the capacitor C1 and the resistor R1. Is done.

  Here, the delay time d is longer than the response time required for the current control unit 14 to increase the charging voltage Vout by the set voltage value represented by the set voltage value Vm by the power supply unit 11 in order to increase the output current Iout. It is set for a long time.

  In addition, the set reference voltage Vmin representing the set voltage value Vm is charged during the delay time d by the constant current charging with the current of the set current value Icc in a state where the SOC (State Of Charge) is 0%. In this case, the charging voltage Vout is set to a value larger than the increase value.

  That is, when the secondary battery 21 is charged with a constant current at the set current value Icc, the maximum rate of increase in the terminal voltage of the secondary battery 21 during the period until the SOC of the secondary battery 21 changes from 0% to 100%. The values of the capacitor C1 and the resistor R1 are set so that the rising speed at which the set reference voltage Vmin is added to the voltage value signal Vsen and the rise to the limit voltage value signal Vr is faster than the value.

  In this case, the capacitor C1 and the resistor R1 correspond to an example of a delay unit.

  When the voltage value signal Vsen detected by the voltage detection unit 13 exceeds the limit voltage value signal Vr output from the operational amplifier 161, the comparator 15 sets the request signal Vop requesting a decrease in the charging voltage Vout of the power supply unit 11 to a high level. Output by level. Then, a high-level control signal OP is output from the diode D1 to the power supply unit 11, and the charging voltage Vout of the power supply unit 11 is reduced.

  At this time, since the control signal OP is generated by the logical sum of the request signal Vop and the request signal Iop by the diodes D1 and D2, for example, the request signal Iop (low level) requesting the rise of the charging voltage Vout from the comparator 141. Even if the level is output, the control signal OP is forcibly set to the high level, and the charging voltage Vout decreases. As a result, the charging voltage Vout during the constant current charging is substantially limited to the limit voltage value Vrv or less indicated by the limit voltage value signal Vr.

  The comparator 17 compares the request signal Iop with the request signal Vop. When the request signal Vop exceeds the request signal Iop, that is, when the request signal Iop is at a low level and the request signal Vop is at a high level, charging is stopped. Is output to the power supply unit 11.

  Next, the operation of the charging system 1 configured as described above will be described. FIG. 2 is an explanatory diagram for explaining an example of the operation of the charging system 1. The vertical axis indicates the current of the output current Iout, the voltage of the charging voltage Vout, and the voltage of the limit voltage value Vrv, and the horizontal axis indicates the passage of time.

  In FIG. 2, it is assumed that charging is started from a state where the SOC of the secondary battery 21 is 0%. Then, in the battery pack 20, since the secondary battery 21 is not fully charged, the switching element 22 is turned on by the full charge determination unit 23.

  Then, at the timing T1, constant current charging is started, and based on the feedback control of the current control unit 14, the output current Iout of the set current value Icc is output from the power supply unit 11, and the current detection unit 12, the connection terminal 101, the pack The secondary battery 21 is charged with a constant current through the side connection terminal 201 and the switching element 22.

  Here, assuming that the charging voltage Vout detected by the voltage detector 13 at the timing T1 is the voltage V1, the limit voltage value setting unit 16 adds the set reference voltage Vmin to the voltage value signal Vsen indicating the charging voltage Vout. In addition, the output of the limit voltage value signal Vr that is the addition result is delayed by the time constant of the resistor R1 and the capacitor C1. Then, the limit voltage value Vrv indicated by the limit voltage value signal Vr is a value obtained by adding the set voltage value Vm substantially represented by the set reference voltage Vmin to the voltage V1 at the timing T2 delayed by the delay time d from the timing T1. It becomes.

  The time constant between the resistor R1 and the capacitor C1 is that the rising speed of the limit voltage value Vrv indicated by the limit voltage value signal Vr is constant current charging with the set current value Icc when the secondary battery 21 is in the state of 0% SOC. It is set to be faster than the terminal voltage of the secondary battery 21 when charged, that is, the rate of increase of the charging voltage Vout.

  Therefore, the limit voltage value Vrv rises faster than the charging voltage Vout rises between timings T1 and T2, and therefore, at the timing T2, the limit voltage value Vrv exceeds the charging voltage Vout.

  Here, the rising speed of the terminal voltage of the secondary battery 21, that is, the charging voltage Vout, is the fastest when the SOC is charged from 0% in the period from 0% to 100%. The speed at which the limit voltage value Vrv increases is faster than the charging voltage Vout even when the charging voltage Vout increases at the fastest SOC of 0%. Therefore, the switching element 22 is not turned off in the battery pack 20 and constant current charging is performed. As long as it continues, the limit voltage value Vrv exceeds the charging voltage Vout, that is, the comparator 15 maintains the state where the limit voltage value signal Vr exceeds the voltage value signal Vsen.

  In the comparator 15, if the limit voltage value signal Vr exceeds the voltage value signal Vsen, the comparator 15 outputs a low level request signal Vop to the diode D 1, and therefore the request signal of the current control unit 14 is output by the OR circuit 18. Iop is output as it is to the power supply unit 11 as the control signal OP, and constant current charging is continued.

  Then, as the constant current charging is continued and the secondary battery 21 is charged, the charging voltage Vout gradually increases, and the limiting voltage value setting unit 16 limits the charging voltage Vout as the charging voltage Vout increases. The voltage value signal Vr, that is, the limit voltage value Vrv indicated by the limit voltage value signal Vr is increased.

  Here, the difference between the limit voltage value Vrv and the charging voltage Vout at a certain timing increases as the charging voltage Vout increases slowly, and becomes the maximum when the charging voltage Vout becomes constant. At this time, the difference between the limit voltage value Vrv and the charging voltage Vout becomes a set voltage value Vm represented by the set reference voltage Vmin. That is, the limit voltage value Vrv does not exceed a value obtained by adding the charging voltage Vout and the set voltage value Vm at a certain timing.

  In this way, constant current charging continues and the secondary battery 21 is charged. For example, when the terminal voltage of the secondary battery 21 becomes equal to or higher than a preset full charge voltage, the full charge determination unit 23 turns off the switching element 22 and interrupts the charge current of the secondary battery 21 ( Timing T3).

  Then, since the output current Iout becomes zero, the current control unit 14 requests the power supply unit 11 to increase the charging voltage Vout so as to maintain the charging current of the set current value Icc. Specifically, when the output current Iout becomes zero, the current value signal Isen output from the current detection unit 12 becomes a voltage value indicating zero, and in the comparator 141, the voltage of the current value signal Isen is the current setting reference voltage Vir. The low-level request signal Iop, that is, the request signal requesting the rise of the charging voltage Vout is output from the comparator 141 to the diode D2, and the low-level control signal OP is output from the diode D2 to the power supply unit 11. The unit 11 rapidly increases the charging voltage Vout.

  Then, the voltage value signal Vsen output from the voltage detector 13 exceeds the limit voltage value signal Vr, the high level request signal Vop is output from the comparator 15, and the control signal OP output from the OR circuit 18 is output. Regardless of the request signal Iop, the signal is set to the high level and output to the power supply unit 11. Then, since the power supply unit 11 decreases the charging voltage Vout, the charging voltage Vout is limited to approximately the limit voltage value Vrv or less.

  Here, the delay time d is longer than the response time required for the current control unit 14 to increase the charging voltage Vout by the set voltage value represented by the set voltage value Vm by the power supply unit 11 in order to increase the output current Iout. Since it is set to a long time, the time from the timing T3 when the charging current is cut off to the timing T4 when the charging voltage Vout reaches the limit voltage value Vrv is shorter than the delay time d.

  Therefore, the value of the limit voltage value Vrv at the timing T4 hardly reflects the charging voltage Vout that has rapidly increased after the timing T3. Therefore, the limit voltage value Vrv at the timing T4 is almost before the timing T3. The charging voltage Vout is a voltage value obtained by adding the set voltage value Vm.

  At timing T4, when the high-level request signal Vop is output from the comparator 15, the request signal Iop is at a low level to increase the charging current. Therefore, in the comparator 17, the request signal Vop is changed to the request signal Iop. Beyond this, a high-level charge stop signal STOP requesting to stop charging is output to the power supply unit 11.

  Then, the power supply unit 11 sets the charging voltage Vout to zero and stops charging (timing T5).

  As described above, as shown in the timing T3, in the charging system 1 shown in FIG. 1, when the secondary battery 21 is fully charged, the battery pack 20 detects the full charge and cuts off the charging current. Can be used for charging the battery pack 20 having a different full charge voltage regardless of the full charge voltage of the battery pack 20. Therefore, it is not necessary to prepare a charging device corresponding to a different full charge voltage for each battery pack having a different full charge voltage.

  In addition, as shown in timing T4, even when the charging current is interrupted during constant current charging, the charging voltage Vout is almost the same as the set voltage value before the charging voltage Vout suddenly rises due to current control feedback. It is limited by the limit voltage value Vrv to which Vm is added. Accordingly, since the charging voltage Vout is not increased to the maximum voltage that can be output by the power supply unit 11 in order to maintain a constant charging current, the output voltage is excessively exceeded when the charging current is cut off on the battery pack side. The risk of rising can be reduced.

  In addition, the charging voltage Vout when the full charge determination unit 23 detects full charge at timing T3 is nothing but the full charge voltage of the secondary battery 21. Then, at timing T <b> 4, the limit voltage value Vrv where the charging voltage Vout is limited is substantially a value obtained by adding the set voltage value Vm to the fully charged voltage of the secondary battery 21.

  As a result, whatever the full charge voltage of the secondary battery 21 is, the voltage applied between the pack side connection terminals 201 and 202 of the battery pack 20 is substantially equal to the full charge voltage of the secondary battery 21. The set voltage value Vm is limited to the added value. As a result, the voltage withstand voltage of the switching element 22 can be set to a voltage obtained by adding a margin to the value obtained by adding the set voltage value Vm to the full charge voltage of the secondary battery 21, and it is necessary to use an excessively high withstand voltage switching element. There is no.

  Note that the comparator 17 (stop control unit) indicates that the request signal Vop is at a high level (the charging voltage Vout exceeds the limit voltage value Vrv), and the request signal Iop is at a low level (the current value indicated by the current value signal Isen). In the example, the charging is stopped in the case of the current setting reference voltage Vir being less than the set current value). However, for example, the comparator 17 is not provided, and the request signal Vop output from the comparator 15 is used as the charge stop signal STOP. As a result, the charging may be stopped when the request signal Vop becomes a high level (the charging voltage Vout exceeds the limit voltage value Vrv). In this case, the comparator 15 corresponds to an example of a stop control unit.

  However, if charging is stopped only under the condition that the charging voltage Vout exceeds the limit voltage value Vrv, malfunction due to noise is likely to occur. On the other hand, according to the comparator 17, both the condition that the charging voltage Vout exceeds the limit voltage value Vrv and the condition that the current value indicated by the current value signal Isen is lower than the set current value indicated by the current setting reference voltage Vir are both If it does not hold, charging will not be stopped, so that the possibility of accidentally stopping charging due to noise is reduced.

  In addition, it is good also as a structure by which the some battery pack 20a, 20b is connected to the charging device 10a like the charging system 1a shown in FIG. The battery packs 20a and 20b are configured in the same manner as the battery pack 20, and the full charge voltages of the secondary batteries 21 are different from each other.

  The charging device 10a includes, for example, connection terminals 101a and 102a for connecting to pack side connection terminals 201 and 202 in the battery pack 20a, and connection terminals 101b for connecting to pack side connection terminals 201 and 202 in the battery pack 20b. 102b.

  The connection terminal 101a is connected to the power supply unit 11 via the changeover switch SW1 and the current detection unit 12. The connection terminal 101b is connected to the power supply unit 11 via the changeover switch SW2 and the current detection unit 12. The connection terminals 102a and 102b are connected to circuit ground.

  Charging device 10a is otherwise configured in the same manner as charging device 10 shown in FIG. When the battery pack 20a is charged, the changeover switch SW1 is turned on and the changeover switch SW2 is turned off. When the battery pack 20b is charged, the changeover switch SW1 is turned off and the changeover switch SW2 is turned on to fully charge the battery pack 20a. Battery packs 20a and 20b having different voltages can be charged in the same manner as the charging device 10 by the charging device 10a.

  The current detector 12 and the voltage detector 13 represent the detected output current Iout and the charging voltage Vout as analog values as the current value signal Isen and the voltage value signal Vsen, respectively. In the example, addition and delay are performed in the circuit, and the current control unit 14, the comparator 15, and the comparator 17 perform an analog voltage level comparison operation. For example, the current detection unit 12 and the voltage detection unit 13 output current A configuration in which Iout and the charging voltage Vout are detected by converting them into digital values, and operations such as addition, delay, and comparison are performed by digital calculation may be employed.

  A charging device according to the present invention and a charging system using the same include, for example, portable personal computers, digital cameras, electronic devices such as mobile phones, vehicles such as electric cars and hybrid cars, hybrid elevators, solar cells, and power generation devices. And a charging system in which such a charging device and a battery pack are combined.

DESCRIPTION OF SYMBOLS 1,1a Charging system 10,10a Charging apparatus 11 Power supply part 12 Current detection part 13 Voltage detection part 14 Current control part 15, 17, 141 Comparator 16 Limit voltage value setting part 18 OR circuit 20, 20a, 20b Battery pack 21 2 Secondary battery 22 Switching element 23 Full charge determination unit 101, 101a, 101b, 102, 102a, 102b Connection terminal 142 Current setting reference voltage source 161 Operational amplifier 162 Setting voltage source 201, 202 Pack side connection terminal C1 Capacitor D1, D2 Diode Icc Set current value Iop, Vop Request signal Iout Output current Isen Current value signal OP Control signal R1, R2, R3, R4, R5 Resistance STOP Charge stop signal SW1, SW2 changeover switch Vir Current setting reference voltage Vm Set voltage value Vmin Setting voltage Vout Charging voltage Vr Limit voltage value signal Vrv Limit voltage value Vsen Voltage value signal d Delay time

Claims (9)

A connection terminal for connecting to a battery pack including a secondary battery;
A power supply unit that outputs a charging voltage for charging the secondary battery to the battery pack via the connection terminal;
A current detection unit for detecting a current value flowing from the power source unit to the secondary battery via the connection terminal;
A voltage detector for detecting the value of the charging voltage as a charging voltage value;
A current control unit that performs constant current charging by controlling the charging voltage output by the power supply unit so that the current value detected by the current detection unit becomes a preset set current value;
A limiting voltage value indicating a limiting voltage to limit the charging voltage by increasing the charging voltage value detected by the voltage detecting unit by a preset setting voltage value and delaying the charging voltage value by a preset delay time. A limit voltage value setting unit for generating
A charging device comprising: a voltage limiting unit that limits a charging voltage in constant current charging by the current control unit by a limiting voltage value generated by the limiting voltage value setting unit. When the charge voltage value detected by the voltage detection unit exceeds the limit voltage value generated by the limit voltage value setting unit, the system further comprises a stop control unit that stops the output of the charge voltage by the power source unit. The charging device according to claim 1. When the charge voltage value detected by the voltage detection unit exceeds the limit voltage value generated by the limit voltage value setting unit, and the current value detected by the current detection unit is less than the set current value, The charging device according to claim 1, further comprising a stop control unit that stops output of the charging voltage by the power source unit. The set voltage value is
When the secondary battery is charged during the delay time by constant current charging with the current of the set current value when the SOC is 0%, the secondary battery has a larger value than the increase value of the terminal voltage of the secondary battery. It is set. The charging device of any one of Claims 1-3 characterized by the above-mentioned. The delay time is
Longer than the response time required for the current control unit to increase the charging voltage by the set voltage represented by the set voltage value by the power supply unit in order to increase the current value detected by the current detecting unit. It is set to time. The charging device of any one of Claims 1-4 characterized by the above-mentioned. The limit voltage value setting unit includes:
An addition unit for adding the charging voltage value detected by the voltage detection unit and the set voltage value;
The delay part which delays the delay time based on a preset time constant and outputs the added value added by the adder to the voltage limiter as the limit voltage value. The charging device according to any one of 1 to 5. The current controller is
When the current value detected by the current detection unit exceeds the set current value, a request signal for lowering the charging voltage is output to the power supply unit, and the current value detected by the current detection unit is When the set current value is not reached, by outputting a request signal for increasing the charging voltage to the power supply unit, the output current value by the power supply unit is controlled to the set current value,
The voltage limiter is
When the charging voltage value detected by the voltage detection unit exceeds the limit voltage value, the power supply unit outputs a request signal to the effect that the charging voltage is reduced,
The current control unit and the voltage limiter are logically ORed with a request signal for reducing the charging voltage from the current control unit and a request signal for reducing the charging voltage from the voltage control unit. When a request signal for decreasing the charging voltage is output from any one of the units, a control signal for decreasing the charging voltage is output to the power supply unit, and the current control unit and the voltage limiter are output. When any request signal for decreasing the charging voltage is not output from any of the units, the circuit further comprises an OR circuit that outputs a control signal for increasing the charging voltage to the power supply unit. The charging device according to any one of claims 1 to 6. The charging device according to any one of claims 1 to 7,
The battery pack,
The battery pack is
A pack-side connection terminal connected to the connection terminal;
A switching element that opens and closes a connection between the pack-side connection terminal and the secondary battery;
A charging system comprising: a full charge determination unit that determines whether or not the secondary battery is fully charged and turns off the switching element when the secondary battery is fully charged. A plurality of the battery packs and a plurality of connection terminals for connecting to each of the battery packs,
The charging system according to claim 8, further comprising a changeover switch that switches connection between the power supply unit and the plurality of connection terminals.

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