JP2014075953A - Battery charger and voltage equalization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery charger and a voltage equalization method that shorten the time needed to equalize a battery voltage and improve precision of equalization of the battery voltage.SOLUTION: When the voltage across a first battery reaches a first target voltage or when the voltage across a second battery reaches a second target voltage, cross control as pulse-width modulation processing for constant-current control is stopped. Then equalization correction control starts as pulse-width modulation processing for performing constant-current control so that the voltage across the first battery or the voltage across the second battery does not exceed a second range which is smaller than a first range determined based upon the first target voltage and second target voltage and determined with the value obtained by subtracting a first threshold from an average voltage and the voltage obtained by adding the first threshold to the average voltage. Further, when the voltage across the first battery or the voltage across the second battery reaches the average voltage, the pulse-width modulation processing for the equalization correction control is stopped.

Description

  The present invention relates to a battery charger and a voltage equalizing method for equalizing voltages of a plurality of batteries.

  When performing cell balance processing that equalizes the voltage of each battery for a plurality of batteries connected in series, the voltage of each battery measured during discharging or charging is affected by the internal resistance of the battery. It is known that the voltage is different from the voltage that should be output. For example, when performing a cell balance process that finds a target voltage that is the target and aligns the voltage of each battery to the target voltage, the voltage that each battery actually reaches is not affected by the internal resistance and becomes the target voltage. It will shift to. Further, when the cell balance process is repeatedly performed to correct this deviation, there is a problem that it takes time until the voltages of the respective batteries are equalized.

  As a related technique, there is known a method for charging an assembled battery in which a plurality of lithium ion secondary batteries connected in series are charged at a constant current and a constant voltage to be fully charged. According to this charging method, constant current charging is performed until the total voltage of the assembled battery rises to the total set voltage, and after the total voltage rises to the total set voltage, the constant current charge is switched to the constant voltage charge to fully charge. Charge until Further, each battery voltage to be charged is detected, and after any of the battery voltages exceeds the set voltage, the charging is switched to the pulse charging. As a result, while using a simple charging circuit, the assembled battery in which the batteries connected in series are in an unbalanced state is charged as large as possible while reducing the adverse effect on the deteriorated battery.

  As a related technique, a state-of-charge equalization apparatus that equalizes the state of charge of each cell for an assembled battery formed by connecting a plurality of cells in series is known. A charge state equalization apparatus includes a plurality of discharge circuits connected in parallel to each cell to discharge each cell, a plurality of voltage measurement circuits and a control circuit connected to each discharge circuit to measure a voltage across each cell It has. The control circuit includes means for calculating the equalization target voltage based on the measured voltage before the start of discharge, and means for starting discharge for a cell whose both-end voltage exceeds the equalization target voltage. Further, for each of these cells, the corrected equalized target voltage is calculated by correcting the equalized target voltage based on the difference between the measured voltage before the start of discharge and the measured voltage after a certain time has elapsed since the start of discharge. And means for terminating the discharge when the measured voltage reaches the corrected equalization target voltage.

JP 2008-210694A JP 2009-159794 A

  The present invention has been made in view of the above circumstances, and provides a battery charger and a voltage equalization method for reducing the time for equalizing the battery voltage and improving the accuracy for equalizing the battery voltage. With the goal.

  A battery charger as one of embodiments includes an assembled battery, a coil, a first switch, a second switch, a voltage measurement unit, a current measurement unit, an adjustment voltage calculation unit, a target voltage calculation unit, and a pulse width modulation unit. Have.

  In the assembled battery, a first battery and a second battery are connected in series. One terminal of the coil is connected to the negative terminal of the first battery and the positive terminal of the second battery. The first switch is connected between the positive terminal of the first battery and the other terminal of the coil. The second switch is connected between the negative terminal of the second battery and the other terminal of the coil. The voltage measuring unit measures the voltages of the first battery and the second battery. The current measurement unit measures the currents of the first battery and the second battery. The pulse width modulation unit controls the opening and closing of the first switch and the second switch to execute a pulse width modulation process for performing constant current control.

  The adjustment voltage calculation unit estimates the internal resistance of the battery. The estimation of the internal resistance of the battery includes a method of obtaining from the current output amount and the voltage fluctuation amount, and a method of obtaining from the battery voltage (open circuit voltage OCV) and the battery temperature when no current is flowing. The adjustment voltage calculation part calculates | requires the internal resistance of a battery using these methods. The following shows a control method using a method obtained from the current output amount and the voltage fluctuation amount.

  A first adjustment voltage that is a difference between the start voltage of the first battery before the start of the pulse width modulation process and the voltage of the first battery after the lapse of a predetermined time is obtained. A second adjustment voltage that is a difference between the start voltage of the second battery before the start of the pulse width modulation process and the voltage of the second battery after a predetermined time has elapsed is obtained.

  The target voltage calculation unit obtains an average voltage from the average of the voltage of the first battery and the voltage of the second battery. Then, the first target voltage of the first battery is obtained using the average voltage and the adjustment voltage of the first battery, and the second target of the second battery is obtained using the average voltage and the adjustment voltage of the second battery. Find the voltage.

  The pulse width modulation unit is a pulse width modulation process for performing constant current control when the voltage of the first battery becomes the first target voltage or when the voltage of the second battery becomes the second target voltage. Stop certain cross control. Subsequently, a first value determined by a value obtained by subtracting the first threshold value from the average voltage and a value obtained by adding the first threshold value to the average voltage, which is smaller than the first range determined by the first target voltage and the second target voltage. The range 2 is shifted to equalization correction control which is pulse width modulation processing for performing constant current control so that the voltage of the first battery or the voltage of the second battery does not exceed. Further, when the voltage of the first battery or the voltage of the second battery falls within a range in which the pulse width modulation process including the average voltage is stopped, the pulse width modulation process for performing the equalization correction control is stopped.

  The battery charging device which is one of the other embodiments includes an assembled battery, a coil, a first switch, a second switch, a voltage measurement unit, a current measurement unit, an adjustment voltage calculation unit, a target voltage calculation unit, and pulse width modulation. Has a part.

  In the assembled battery, a first battery and a second battery are connected in series. One terminal of the coil is connected to the negative terminal of the first battery and the positive terminal of the second battery. The first switch is connected between the positive terminal of the first battery and the other terminal of the coil. The second switch is connected between the negative terminal of the second battery and the other terminal of the coil. The voltage measuring unit measures the voltages of the first battery and the second battery. The current measurement unit measures the currents of the first battery and the second battery. The pulse width modulation unit controls the opening and closing of the first switch and the second switch to execute a pulse width modulation process for performing constant current control.

  The adjustment voltage calculation unit estimates the internal resistance of the battery. The estimation of the internal resistance of the battery includes a method of obtaining from the current output amount and the voltage fluctuation amount, and a method of obtaining from the battery voltage (open circuit voltage OCV) and the battery temperature when no current is flowing. The adjustment voltage calculation part calculates | requires the internal resistance of a battery using these methods. The following shows a control method using a method obtained from the current output amount and the voltage fluctuation amount.

  A first adjustment voltage that is a difference between the start voltage of the first battery before the start of the pulse width modulation process and the voltage of the first battery after the lapse of a predetermined time is obtained. A second adjustment voltage that is a difference between the start voltage of the second battery before the start of the pulse width modulation process and the voltage of the second battery after a predetermined time has elapsed is obtained.

  The target voltage calculation unit obtains an average voltage from the average of the voltage of the first battery and the voltage of the second battery. Then, the first target voltage of the first battery is obtained using the average voltage and the adjustment voltage of the first battery, and the second target of the second battery is obtained using the average voltage and the adjustment voltage of the second battery. Find the voltage.

  The pulse width modulation unit is a pulse width modulation process for performing constant current control when the voltage of the first battery becomes the first target voltage or when the voltage of the second battery becomes the second target voltage. Stop certain cross control. Subsequently, the voltage of the first battery or the voltage of the second battery is set to a value obtained by subtracting the first correction voltage from the first target voltage or a value obtained by adding the first correction voltage to the second target voltage. When this happens, the process proceeds to the second cross control for performing constant current control. Further, when the voltage of the first battery is in a range including the third target voltage or the voltage of the second battery is in a range including the fourth target voltage, the second cross control is performed. Stop the pulse width modulation process.

  The battery charging device which is one of the other embodiments includes an assembled battery, a coil, a first switch, a second switch, a voltage measurement unit, a current measurement unit, an adjustment voltage calculation unit, a target voltage calculation unit, and pulse width modulation. Has a part.

  In the assembled battery, a first battery and a second battery are connected in series. One terminal of the coil is connected to the negative terminal of the first battery and the positive terminal of the second battery. The first switch is connected between the positive terminal of the first battery and the other terminal of the coil. The second switch is connected between the negative terminal of the second battery and the other terminal of the coil. The voltage measuring unit measures the voltages of the first battery and the second battery. The current measurement unit measures the currents of the first battery and the second battery. The pulse width modulation unit controls the opening and closing of the first switch and the second switch to execute a pulse width modulation process for performing constant current control.

  The adjustment voltage calculation unit estimates the internal resistance of the battery. The estimation of the internal resistance of the battery includes a method of obtaining from the current output amount and the voltage fluctuation amount, and a method of obtaining from the battery voltage (open circuit voltage OCV) and the battery temperature when no current is flowing. The adjustment voltage calculation part calculates | requires the internal resistance of a battery using these methods. The following shows a control method using a method obtained from the current output amount and the voltage fluctuation amount.

  A first adjustment voltage that is a difference between the start voltage of the first battery before the start of the pulse width modulation process and the voltage of the first battery after the lapse of a predetermined time is obtained. A second adjustment voltage that is a difference between the start voltage of the second battery before the start of the pulse width modulation process and the voltage of the second battery after a predetermined time has elapsed is obtained.

  The target voltage calculation unit obtains an average voltage from the average of the voltage of the first battery and the voltage of the second battery. Then, the first target voltage of the first battery is obtained using the average voltage and the adjustment voltage of the first battery, and the second target of the second battery is obtained using the average voltage and the adjustment voltage of the second battery. Find the voltage.

  The pulse width modulation unit is a pulse width modulation process for performing constant current control when the voltage of the first battery becomes the first target voltage or when the voltage of the second battery becomes the second target voltage. Stop certain cross control. Subsequently, a first value determined by a value obtained by subtracting the first threshold value from the average voltage and a value obtained by adding the first threshold value to the average voltage, which is smaller than the first range determined by the first target voltage and the second target voltage. When the voltage of the first battery or the voltage of the second battery exceeds the range of 2, the process shifts to a pulse width modulation process for performing constant voltage control so as not to exceed the second range. Further, when the voltage of the first battery or the voltage of the second battery falls within a range in which the pulse width modulation process including the average voltage is stopped, the pulse width modulation process for performing the constant voltage control is stopped.

  According to the present embodiment, it is possible to shorten the time for equalizing the battery voltage and to improve the accuracy for equalizing the battery voltage.

It is a figure which shows one Example of a battery charging device. It is a figure which shows the relationship between 1 set of the battery to discharge, and the battery to charge. It is a figure which shows the change of the battery voltage in cross control. It is a figure which shows one Example of a control part. FIG. 6 is a flowchart showing an example of the operation of the battery charger in the first embodiment. FIG. 6 is a flowchart showing an example of the operation of the battery charger in the first embodiment. It is a figure which shows the change of a voltage and an electric current in flowing a fixed electric current. FIG. 10 is a flowchart showing an example of the operation of the battery charger in the second embodiment. It is a figure which shows the change of the voltage and electric current in the cross control which flows a fixed electric current. FIG. 10 is a flowchart showing an example of operation of the battery charging device in the third exemplary embodiment. It is a figure which shows the change of the voltage and electric current in a cell balance process using constant voltage control. It is a figure which shows the change of the voltage and electric current in a cell balance process using constant voltage control.

Hereinafter, embodiments will be described in detail based on the drawings.
The first embodiment will be described.
FIG. 1 is a diagram illustrating an embodiment of a battery charger. The battery charger of FIG. 1 has an assembled battery and a cell balance circuit. The assembled battery is a circuit in which a plurality of batteries 3a to 3d are connected in series. The cell balance circuit includes a control unit 1, a storage unit 2, voltage measurement units 4a to 4d, current measurement units 5a to 5d, coils L1 to L3, and switches SW1 to SW7. In the active type cell balance circuit shown in FIG. 1, the control unit 1 controls the switches SW1 to SW6 by PWM (Pulse Width Modulation), so that the voltages of the batteries 3a to 3d are equalized using the coils L1 to L3. .

  The cell balance circuit of the present embodiment performs 1) cross control to reduce the time for equalizing the voltages of the batteries 3a to 3d, and 2) equalization correction control for improving the accuracy of equalizing the battery voltage.

1) Cross control will be described.
When the cell balance processing is performed on the battery 3a, 3b group, the battery 3b, 3c group, and the battery 3c, 3d group in FIG. When the balancing process is stopped, the actual voltages of the batteries 3a to 3d are deviated from the target average voltage. That is, from the average voltage of each battery of each set, the time from the time when the voltage of each of the batteries 3a to 3d becomes equal to the voltage determined by the internal resistance of each of the batteries 3a to 3d and the current flowing through each of the batteries 3a to 3d. It will shift as time passes. When the cell balance process is repeatedly performed to adjust the voltage deviation, it takes time until the voltages of the batteries 3a to 3d become equal.

  Therefore, the internal resistances of the batteries 3a to 3d are estimated, the adjustment voltage is obtained according to the estimated internal resistance, and the target voltage of the battery to be discharged and the battery to be charged in each group is expressed by Equation 1, The voltages Vt1 and Vt2 shown in Equation 2 are set. Then, after the magnitude relationship between the voltage of the battery that discharges and the voltage of the battery that charges the battery in each group is reversed (crossed), constant current control is performed until the target voltages Vt1 and Vt2 are reached. After the constant current control is stopped, the battery voltage is equalized by using the estimated relaxation of the internal resistance. By using such constant current control, the time for equalizing the voltages of the batteries 3a to 3d can be shortened.

The target voltage will be described with reference to FIGS.
FIG. 2 is a diagram illustrating a relationship between a set of discharging batteries and charging batteries. FIG. 3 is a diagram illustrating a change in battery voltage in the cross control. FIG. 3A is a diagram showing a change in battery voltage when the battery 3a of FIG. 2 is a discharging battery and the battery 3b is a charging battery. FIG. 3B is a diagram showing a change in battery voltage when the battery 3b of FIG. 2 is a discharging battery and the battery 3a is a charging battery. The current Iup shown in FIG. 2 is a current that flows from the battery 3a to the battery 3b using the coil L1 when the initial voltage Vup0 of the battery 3a is higher than the initial voltage Vun0 of the battery 3b. The current Iun shown in FIG. 2 is a current that flows from the battery 3b to the battery 3a using the coil L1 when the initial voltage Vun0 of the battery 3b is higher than the initial voltage Vup0 of the battery 3a.

  3A and 3B is a voltage measured by the voltage measuring unit 4a of the battery 3a, and the voltage Vun is a voltage measured by the voltage measuring unit 4b of the battery 3b. The voltage Vup0 of A and B in FIG. 3 is the initial voltage of the battery 3a, and the voltage Vun0 is the initial voltage of the battery 3b. The voltage Vup1 of A and B in FIG. 3 is the voltage of the battery 3a after the elapse of time t1 determined based on the characteristics of the battery in order to measure the internal resistance, and the voltage Vun1 is the voltage of the battery 3b after the elapse of time t1. is there.

The target voltage Vt1 of the battery that discharges and the target voltage Vt2 of the battery that charges the battery are obtained by equations 1 to 4.
In the case of the battery 3a to be discharged and the battery 3b to be charged: target voltage Vt1 = average voltage VaVg−regulated voltage V1 Equation 1
Target voltage Vt2 = average voltage VaVg + adjusted voltage V2 Equation 2
Vt1: target voltage of the battery to be charged Vt2: target voltage of the battery to be discharged VaVg: average voltage of the battery for each set V1: voltage determined according to the internal resistance (Vup0−Vup1)
V2: voltage determined according to internal resistance (Vun1-Vun0)
In the case of the discharging battery 3b and the charging battery 3a, the target voltage Vt1 = the average voltage VaVg + the adjustment voltage V1 Equation 3
Target voltage Vt2 = average voltage VaVg−regulated voltage V2 Equation 4
V1: voltage determined according to internal resistance (Vup1-Vup0)
V2: Voltage determined according to the internal resistance (Vun0-Vun1)
However, the average voltages (V1 + V2) / 2 of the adjustment voltages V1 and V2 may be obtained in the equations 1 to 4 to obtain the adjustment voltages V1 and V2.

2) The equalization correction control will be described.
When cross control is performed by an active cell balance circuit, it is difficult to equalize the voltages because the target voltages Vt1 and Vt2 are obtained by estimating the internal resistance. That is, in the time for equalizing the battery voltage using relaxation of the internal resistance, the estimated accuracy of the internal resistance and other factors affect the accuracy of equalizing the voltage. Therefore, after the constant current control is stopped (after the cross control is performed), the control for converging to the average voltage is performed to improve the accuracy of equalizing the voltages. In the first embodiment, the constant current control is intermittently repeated after the constant current control is stopped.

The configuration of the battery charging device will be described.
The control unit 1 in FIG. 1 may use a Central Processing Unit (CPU), a multi-core CPU, and a programmable device (Field Programmable Gate Array (FPGA), Programmable Logic DeVice (PLD), etc.). The control unit 1 includes, for example, an adjustment voltage calculation unit 401, a target voltage calculation unit 402, a pulse width modulation unit 403, which will be described later.

  The storage unit 2 may be a memory such as a read only memory (ROM) or a random access memory (RAM), a hard disk, or the like. Data such as parameter values and variable values may be recorded in the storage unit 2 or may be used as a work area at the time of execution.

  The batteries 3a to 3d may be secondary batteries or capacitors. As the secondary battery, for example, a lithium ion secondary battery, a nickel hydride secondary battery, or the like can be considered. In this example, four batteries are used for explanation, but the number of batteries is not limited to four.

Voltage measuring units 4a to 4d measure voltages of batteries 3a to 3d. For example, a voltmeter can be considered. Data measured by the voltage measuring units 4 a to 4 d is output to the control unit 1.
The current measuring units 5a to 5d measure current. For example, an ammeter can be considered. Further, data measured by the current measuring units 5 a to 5 d is output to the control unit 1.

  In the example of FIG. 1, the current flowing through each of the batteries 3 a to 3 d is obtained using the current measured by the current measuring units 5 a to 5 d provided at the positions shown in the figure, but the current flowing through each of the batteries 3 a to 3 d. The method of obtaining is not limited to the above method. For example, an ammeter may be connected in series to the negative electrode side of each of the batteries 3a to 3d, and the current flowing through each of the batteries 3a to 3d may be measured and obtained.

  The coils L1 to L3 are used for charging the electric power discharged from the discharging batteries for each set in the coils L1 to L3, and then supplying the electric power stored in the coils L1 to L3 to the charging battery. .

  The switches SW1 to SW7 are switches used for performing cell balance processing. For example, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) and relays are used for the switches SW1 to SW7.

Connection of the battery charger will be described.
In the battery charger of FIG. 1, voltage measuring units 4a to 4d are connected to both ends of the batteries 3a to 3d, respectively. Further, one terminal of the switch SW7 is connected to the load side and the external power source side, and the other terminal of the switch SW7 is connected to one terminal of the current measuring unit 5a. The other terminal of the current measuring unit 5a is connected to the positive terminal of the battery 3a, and the negative terminal of the battery 3d is connected to the load side and the external power source side.

  The negative terminal of the battery 3a, the positive terminal of the battery 3b, and one terminal of the current measuring unit 5b are connected, and the other terminal of the current measuring unit 5b is connected to one terminal of the coil L1. The other terminal of the coil L1 is connected to one terminal of the switches SW1 and SW2, and the other terminal of the switch SW1 is connected to the positive terminal of the battery 3a. The other terminal of the switch SW2 is connected to the negative terminal of the battery 3b.

  The negative terminal of the battery 3b, the positive terminal of the battery 3c, and one terminal of the current measuring unit 5c are connected, and the other terminal of the current measuring unit 5c is connected to one terminal of the coil L2. The other terminal of the coil L2 is connected to one terminal of the switches SW3 and SW4, and the other terminal of the switch SW3 is connected to the positive terminal of the battery 3b. The other terminal of the switch SW4 is connected to the negative terminal of the battery 3c.

  The negative terminal of the battery 3c, the positive terminal of the battery 3d, and one terminal of the current measuring unit 5d are connected, and the other terminal of the current measuring unit 5d is connected to one terminal of the coil L3. The other terminal of the coil L3 is connected to one terminal of the switches SW5 and SW6, and the other terminal of the switch SW5 is connected to the positive terminal of the battery 3c. The other terminal of the switch SW6 is connected to the negative terminal of the battery 3d.

FIG. 4 is a diagram illustrating an example of the control unit. The control unit 1 monitors whether a constant current is supplied to the batteries 3a to 3d during the constant current control.
In the case of a set of batteries 3a and 3b, the adjustment voltage calculation unit 401 of the control unit 1 is a battery 3a after the elapse of time t1 determined as the start voltage of the battery 3a (first battery) before the start of the pulse width modulation process. An adjustment voltage V1 (first adjustment voltage), which is a difference from the above voltage, is obtained. An adjustment voltage V2 (second adjustment voltage) that is a difference between the start voltage of the battery 3b (second battery) before the start of the pulse width modulation process and the voltage of the battery 3b after the lapse of the determined time t1 is obtained.

  The target voltage calculation unit 402 of the control unit 1 calculates an average voltage VaVg from the average of the voltage of the battery 3a and the voltage of the battery 3b in the case of the set of the batteries 3a and 3b. Then, the target voltage Vt1 of the battery 3a is obtained using the average voltage VaVg and the adjustment voltage V1 of the battery 3a, and the target voltage Vt2 of the battery 3b is obtained using the average voltage VaVg and the adjustment voltage V2 of the battery 3b.

  The pulse width modulation unit 403 of the control unit 1 controls the opening and closing of the switches for each of the sets of the batteries 3a and 3b, the set of the batteries 3b and 3c, and the set of the batteries 3c and 3d in FIG. . In the case of a set of batteries 3a and 3b, the pulse width modulation unit 403 performs pulse width modulation for performing constant current control when the voltage of the battery 3a reaches the target voltage Vt1 or when the voltage of the battery 3b reaches the target voltage Vt2. The cross control that is processing is stopped. Subsequently, constant current control is performed so that the voltage Vup of the battery 3a or the voltage Vun of the battery 3b does not exceed a second range smaller than the first range (see FIG. 7) determined by the target voltage Vt1 and the target voltage Vt2. The process shifts to equalization correction control which is a pulse width modulation process to be performed. The second range is a range represented by a value obtained by subtracting the first threshold value Vs1 from the average voltage VaVg (VaVg−Vs1) and a value obtained by adding the first threshold value Vs1 to the average voltage VaVg (VaVg + Vs1) (see FIG. 7). ).

Further, when the voltage of the battery 3a or the voltage of the battery 3b becomes an average voltage, the pulse width modulation process for performing the equalization correction control is stopped.
The operation of the first embodiment will be described.

  5 and 6 are flowcharts showing an example of the operation of the battery charging apparatus according to the first embodiment. A set of the battery 3a and the battery 3b will be described. In steps S501 to S508, the internal resistance is estimated to obtain the adjustment voltages V1 and V2.

  In step S501, the control unit 1 acquires the initial voltages Vup0 and Vun0 of the batteries 3a and 3b from the voltage measurement units 4a and 4b, and stores the initial voltages Vup0 and Vun0 in the storage unit 2 and the like.

  In step S502, the control unit 1 compares the initial voltage Vup0 and the initial voltage Vun0. If the relationship between the initial voltages is Vup0> Vun0 (Yes), the process proceeds to step S503, and if Vup0 <Vun0 (No). In step S504, the process proceeds to step S504. When the initial voltage is Vup0≈Vun0, this set of cell balance processing is not performed. That is, when the voltage difference between the voltage Vup0 and the voltage Vun0 is within a range determined to be equal, the cell balance process is not performed.

In step S503, when the relationship between the initial voltages is Vup0> Vun0, the control unit 1 performs constant current control for flowing a constant current from the battery 3a to the battery 3b.
In step S504, when the relationship between the initial voltages is Vup0 <Vun0, the control unit 1 performs constant current control for flowing a constant current from the battery 3b to the battery 3a.

  In constant current control for supplying a constant current, for example, a constant current is supplied to the battery 3a or the battery 3b using PWM (Pulse Width Modulation) control. Constant current control is performed so that a constant current flows from time 0 to time t3 shown in A and B of FIG. FIG. 7 is a diagram illustrating changes in voltage and current when a constant current is passed from the battery 3a to the battery 3b.

  In step S505, the control unit 1 starts measuring time. In step S506, the time time measured by the control unit 1 is compared with the time t1 determined based on the characteristics of the battery in order to measure the internal resistance, and measurement is performed until time = t1. If time = t1 (Yes), the process proceeds to step S507, and time measurement is stopped in step S507. If time <t1 (No), the process proceeds to step S506.

In step S508, the control unit 1 obtains adjustment voltages V1 and V2 determined according to the internal resistance.
In the case where the battery 3a is a discharged battery and the battery 3b is a charged battery, the adjustment voltage V1 is a value obtained by subtracting the voltage Vup1 measured at time t1 from the initial voltage Vup0 of the battery 3a. The voltage V2 is a value obtained by subtracting the initial voltage Vun0 from the voltage Vun1 measured at time t1 of the battery 3b.

  In the case where the battery 3b is a discharged battery and the battery 3a is charged, the adjustment voltage V1 is a value obtained by subtracting the voltage Vup1 measured at time t1 from the initial voltage Vup0 of the battery 3a. The adjustment voltage V2 is a value obtained by subtracting the initial voltage Vun0 from the voltage Vun1 measured at time t1 of the battery 3b.

Therefore, in step S508, V1 = | Vup0−Vup1 | and V2 = | Vun0−Vun1 | are obtained.
Steps S509 to S513 perform cross control.

  In step S509, the control unit 1 compares the initial voltage Vup0 and the initial voltage Vun0. If the relationship between the initial voltages is Vup0> Vun0 (Yes), the process proceeds to step S510, and if Vup0 <Vun0 (No). In step S511, the process proceeds to step S511. In step S509, it is considered that there is no state in which the initial voltage is Vup0 = Vun0.

  In step S510, the target voltage Vt2 is obtained when the initial voltage relationship is Vup0> Vun0 and the cross control is performed using the voltage Vun of the battery 3b to be charged. For example, Vt2 = (Vup + Vun) / 2 + (V1 + V2) / 2 or Vt2 = (Vup + Vun) / 2 + V2 is used as the target voltage Vt2.

  In step S512, the control unit 1 compares the voltage Vun of the battery 3b to be charged with the target voltage Vt2. If Vun = Vt2 (Yes), the process proceeds to step S513, and if Vun = Vt2 is not satisfied (No). Moves to step S511.

  If the initial voltage relationship is Vup0> Vun0 and cross control is performed using the voltage Vup of the battery 3a to be discharged, the target voltage Vt1 is obtained in step S510. For example, Vt1 = (Vup + Vun) / 2− (V1 + V2) / 2 or Vt1 = (Vup + Vun) / 2−V1 is used as the target voltage Vt1.

  In step S512, the control unit 1 compares the voltage Vup of the battery 3a to be discharged with the target voltage Vt1. If Vun = Vt1 (Yes), the process proceeds to step S513, and if Vun = Vt1 is not satisfied (No). Moves to step S511.

For the steps S510 and S512 described above, see A and B in FIG.
In step S511, the target voltage Vt2 is obtained when the initial voltage relationship is Vup0 <Vun0 and the cross control is performed using the voltage Vun of the battery 3b to be discharged. That is, for example, Vt2 = (Vup + Vun) / 2− (V1 + V2) / 2 or Vt2 = (Vup + Vun) / 2−V2 is used as the target voltage Vt2 when a constant current flows from the battery 3b to the battery 3a.

  In step S512, the voltage Vun of the battery 3b discharged by the control unit 1 compares the target voltage Vt2. If Vun = Vt2 (Yes), the process proceeds to step S513, and if Vun = Vt2 is not satisfied (No). The process proceeds to step S511.

  If the initial voltage relationship is Vup0 <Vun0 and cross control is performed using the voltage Vup of the battery 3a to be charged, the target voltage Vt1 is obtained in step S511. For example, Vt1 = (Vup + Vun) / 2 + (V1 + V2) / 2 or Vt1 = (Vup + Vun) / 2 + V1 is used as the target voltage Vt1. In step S512 in that case, the control unit 1 compares the voltage Vup of the battery 3a to be charged with the target voltage Vt1. If Vun = Vt1 (Yes), the process proceeds to step S513, and if Vun = Vt1 is not satisfied ( In No), the process proceeds to step S511.

In step S513, the control unit 1 stops constant current control for supplying a constant current.
Steps S514 to S519 perform equalization correction control.
In step S514 of FIG. 6, after the control unit 1 stops the constant current control, the voltage Vun of the battery 3b is compared with the average voltage VaVg + the first threshold value Vs1 or the average voltage VaVg−the first threshold value Vs1. For example, the first threshold value Vs1 may be determined in consideration of the measurement accuracy of the voltage measurement units 4a and 4b, the surrounding environment, and the like, and may be stored in advance in the storage unit 2 or the like.

  When the state of VaVg + Vs1 <Vun or VaVg−Vs1> Vun is reached (Yes), the process proceeds to step S515. When VaVg + Vs1 <Vun or VaVg−Vs1> Vun is not satisfied (No), the process proceeds to step S514 and the constant current control is stopped.

For example, when polarization occurs again at time t6 in FIG. 7A and the voltage Vun becomes VaVg−Vs1 at time t7, the process proceeds to step S515 to perform constant current control.
In addition, when polarization is performed again at time t6 in FIG. 7A and the voltage Vun becomes VaVg + Vs1 at time t7, the process proceeds to step S515 to perform constant current control.

In step S514 of this example, the voltage Vun of the battery 3b is used for comparison, but the voltage Vup of the battery 3a may be used.
In step S515, the control unit 1 compares the voltage Vup with the voltage Vun, and if the voltage relationship is Vup> Vun (Yes), the process proceeds to step S516, and if Vup <Vun (No), the process proceeds to step S516. The process proceeds to S518. In step S515, the constant current control is stopped when the voltage is Vup = Vun.

  In step S516, the control unit 1 starts constant current control for flowing a constant current from the battery 3a to the battery 3b. Refer to times t5 to t6, t7 to t8, t9 to t10, and t11 to t12 in A and B of FIG.

  In step S517, the control unit 1 measures the voltage Vun of the battery 3b and compares it with the average voltage VaVg−the second threshold value Vs2. For example, the second threshold value Vs2 may be determined in consideration of the measurement accuracy of the voltage measurement units 4a and 4b, the surrounding environment, and the like, and may be stored in advance in the storage unit 2 or the like with a value of Vs2 <Vs1. It is done. Also, Vs2 may be 0.

  If VaVg−Vs2> Vun (Yes), the process proceeds to step S515. If VaVg−Vs2> Vun is not satisfied (No), the process proceeds to step S513 to stop the constant current control. See times t6, t8, t10, and t12 in A and B of FIG.

  In step S517 of this example, the voltage Vun of the battery 3b is used for comparison, but the voltage Vup of the battery 3a may be used. In this case, if VaVg + Vs2 <Vup (Yes), the process proceeds to step S515. If VaVg + Vs2 <Vup is not satisfied (No), the process proceeds to step S513, and constant current control is stopped.

  In step S518, the control unit 1 starts constant current control for flowing a constant current from the battery 3b to the battery 3a. Refer to times t5 to t6, t7 to t8, t9 to t10, and t11 to t12 in A and B of FIG.

In step S519, the control unit 1 measures the voltage Vun of the battery 3b and compares it with the average voltage VaVg + the second threshold value Vs2.
If VaVg + Vs2 <Vun (Yes), the process proceeds to step S515. If VaVg + Vs2 <Vun is not satisfied (No), the process proceeds to step S513 to stop the constant current control. See times t6, t8, t10, and t12 in A and B of FIG.

  In step S519 of this example, the voltage Vun of the battery 3b is used for comparison, but the voltage Vup of the battery 3a may be used. In this case, if VaVg−Vs2> Vup (Yes), the process proceeds to step S515. When VaVg−Vs2> Vup is not satisfied (No), the process proceeds to step S513 to stop the constant current control.

  In the first embodiment, after the cross control is finished, the polarization is relaxed and the battery voltage difference exceeds the range of VaVg−Vs1 to VaVg + Vs1 (second range). Control is performed so as to approach the range of VaVg−Vs2 to VaVg + Vs2 (the range in which the pulse width modulation process of the equalization correction control is stopped).

According to the first embodiment, it is possible to shorten the time for equalizing the battery voltage and further improve the accuracy for equalizing the battery voltage.
Embodiment 2 will be described.

In the second embodiment, after the first cross control is finished, when the polarization is relaxed and the battery voltage exceeds the newly set target voltage, the cross control is intermittently repeated.
In the case of the combination of the batteries 3a and 3b of the second embodiment, the pulse width modulation unit 403 performs constant current control when the voltage Vup of the battery 3a reaches the target voltage Vt1 or when the voltage Vun of the battery 3b reaches the target voltage Vt2. Therefore, the first cross control that is the pulse width modulation processing is stopped.

  Subsequently, after the first cross control is completed, the polarization is relaxed. When the battery voltage exceeds the set voltage, the second cross control is performed, and the voltage Vup of the battery 3a is set to the target voltage Vt1n (third When the voltage Vun of the battery 3b reaches the target voltage Vt2n (fourth target voltage), the second cross control, which is a pulse width modulation process for performing constant current control, is stopped. It is conceivable that the target voltages Vt1n and Vt2n used in the second and subsequent cross controls are obtained by the same method as in the first cross control.

At this time, Vt1n is close to Vt1, and Vt2n is close to Vt2. Further, the voltage V1n determined according to the internal resistance measured in the second and subsequent cross control is close to V1 measured in the first cross control, and the voltage V2n is close to V2 measured in the first cross control. Value.
The operation of the second embodiment will be described.

  FIG. 8 is a flowchart illustrating an example of the operation of the battery charger according to the second embodiment. A set of the battery 3a and the battery 3b will be described. FIG. 9 is a diagram showing changes in voltage and current in cross control in which a constant current is passed from the battery 3a to the battery 3b.

In the second embodiment, when the processing in steps S501 to S513 in the first embodiment is performed, the process proceeds to steps S801 to S815 to perform equalization correction control (second and subsequent cross control).
In step S801, it is determined whether VaVg + (V2 + Vc1) <Vun or VaVg− (V2 + Vc1)> Vun. If VaVg + (V2 + Vc1) <Vun or VaVg− (V2 + Vc1)> Vun (Yes), the process proceeds to step S802. If not (No), the process proceeds to step S801. In this example, the first adjustment voltage V2 is used, but instead of the adjustment voltage V2, the first target voltages Vt1 and Vt2 may be used to calculate (Vt2−Vt1) / 2.

  The correction voltage Vc1 (first correction voltage) is a value for giving a margin so that the voltage Vun of the battery 3b does not exceed the average voltage VaVg after measuring the second and subsequent adjustment voltages V2n in step S808 described later. It is. See 901, 902 in FIG. 9A and C in FIG. The correction voltage Vc1 may be 0.

  In step S802, the control unit 1 compares the current voltage Vup with the voltage Vun, and if Vup> Vun (Yes), the process proceeds to step S803, and if Vup <Vun (No), the process proceeds to step S804. Transition. When the voltage is Vup≈Vun, this set of cell balance processing is not performed. That is, when the voltage difference between the voltage Vup and the voltage Vun is in a range determined to be equal, the cell balance process is not performed.

In step S803, when the relationship between the initial voltages is Vup> Vun, the control unit 1 performs constant current control for flowing a constant current from the battery 3a to the battery 3b.
In step S804, when the relationship between the initial voltages is Vup <Vun, the control unit 1 performs constant current control for flowing a constant current from the battery 3b to the battery 3a.

  In the constant current control for supplying a constant current, for example, the constant current is supplied to the battery 3a or the battery 3b using PWM control. Constant current control is performed so that a constant current flows from time t4 to time t6 shown in A and B of FIG.

  In step S805, the control unit 1 starts measuring time. In step S806, the time time measured by the control unit 1 is compared with the time t1 determined based on the characteristics of the battery in order to measure the internal resistance, and measurement is performed until time = t4 + t1. When time = t4 + t1 (Yes), the process proceeds to step S807, and time measurement is stopped in step S807. If time <t4 + t1 (No), the process proceeds to step S806.

In step S808, the control unit 1 obtains adjustment voltages V1n and V2n determined according to the internal resistance.
In the case of the second or subsequent cross control in FIG. 9, a voltage difference between the voltage Vup after t1 has elapsed from t4 and the voltage Vup at t4 is obtained as the adjustment voltage V1n. In addition, a voltage difference between the voltage Vun after the elapse of t1 from t4 and the voltage Vun at t4 is obtained as an adjustment voltage V2n.

  In the case of the third or subsequent cross control in FIG. 9, the voltage difference between the voltage Vup after the lapse of t1 from t8 and the voltage Vup at t8 is obtained as the adjustment voltage V1n. In addition, a voltage difference between the voltage Vun after the elapse of t1 from t8 and the voltage Vun at t8 is obtained as an adjustment voltage V2n.

  In step S809, the control unit 1 performs the same comparison as in step S802. If the voltage relationship is Vup> Vun (Yes), the process proceeds to step S810, and if Vup <Vun (No), step S813. Migrate to In step S809, it is considered that the initial voltage is not in the state of Vup = Vun.

  In step S810, a target voltage Vt2n in the case of performing cross control using the voltage Vun of the battery 3b to be charged is obtained. For example, Vt2n = (Vup + Vun) / 2 + (V1n + V2n) / 2 or Vt2n = (Vup + Vun) / 2 + V2n is used as the target voltage Vt2n.

In step S811, the control unit 1 starts constant current control for flowing a constant current from the battery 3a to the battery 3b. Refer to times t4 to t6 and t8 to t10 in A and B of FIG.
In step S812, the control unit 1 determines whether or not Vt2n−Vs3> Vun. If Vt2n−Vs3> Vun (Yes), the process proceeds to step S809, and if Vt2n−Vs3> Vun is not satisfied (No) ) Proceeds to step S513.

  In step S813, a target voltage Vt2n in the case of performing cross control using the voltage Vun of the battery 3b to be charged is obtained. For example, Vt2n = (Vup + Vun) / 2− (V1n + V2n) / 2 or Vt2n = (Vup + Vun) / 2 + V2n is used as the target voltage Vt2n.

In step S814, the control unit 1 starts constant current control for flowing a constant current from the battery 3b to the battery 3a. Refer to times t4 to t6 and t8 to t10 in A and B of FIG.
In step S815, the control unit 1 determines whether or not Vt2n + Vs3 <Vun. If Vt2n + Vs3 <Vun (Yes), the process proceeds to step S809. If Vt2n + Vs3 <Vun is not satisfied (No), the process proceeds to step S513. Transition.

  The third threshold value Vs3 is a value for stopping the pulse width modulation process of the equalization correction control within a range including the target voltage Vt1n or Vt2n. See 901, 903 in FIG. 9A and D in FIG. Note that the third threshold value Vs3 may be zero.

In the second embodiment, after the first cross control is finished, when the polarization is relaxed and the battery voltage exceeds the newly set target voltage, the cross control is intermittently repeated.
According to the second embodiment, it is possible to shorten the time for equalizing the battery voltage and further improve the accuracy for equalizing the battery voltage.

A third embodiment will be described.
In the third embodiment, after the cross control is finished, when the polarization is relaxed and the battery voltage difference exceeds the range of VaVg−Vs1 to VaVg + Vs1, constant voltage control is performed as equalization correction control. As the constant voltage control, for example, PWM control using PID (Proportinal Integral Differential) control can be considered. See FIG. 11 described later.

  Here, in this example, the discrete transfer function Gc (z) when performing PID control is expressed by Equation 5.

From this discrete transfer function Gc (z), a PWM value (duty) represented by Expression 6 is obtained.
PWM value = Previous PWM value
+ (Difference x coefficient k0)
+ (Previous difference x coefficient k1) (Formula 6)
+ (Previous difference x coefficient k2)
Alternatively, constant voltage control may be started at the time when the voltages match due to relaxation of the internal resistance after the cross control is finished, and control may be performed so as to keep the battery voltage difference in a range of VaVg−Vs2 to VaVg + Vs2. See FIG. 12 to be described later.

The operation of the third embodiment will be described.
FIG. 10 is a flowchart illustrating an example of the operation of the battery charger according to the third embodiment. 11 and 12 are diagrams showing changes in voltage and current in cell balance processing using constant voltage control from the battery 3a to the battery 3b.

  In the case of the combination of the batteries 3a and 3b of the third embodiment, the pulse width modulation unit 403 performs constant current control when the voltage Vup of the battery 3a becomes the target voltage Vt1 or when the voltage Vun of the battery 3b becomes the target voltage Vt2. The cross control, which is a pulse width modulation process to be performed, is stopped. Subsequently, when the voltage Vup of the battery 3a or the voltage of the battery 3b exceeds the second range smaller than the first range, pulse width modulation processing for performing constant voltage control so as not to exceed the second range is performed. Transition. Further, when the voltage Vup of the battery 3a or the voltage Vun of the battery 3b reaches the average voltage VaVg, the pulse width modulation process for performing constant voltage control is stopped.

In the third embodiment, after performing the processing from steps S501 to S513 in the first and second embodiments, the processing shown in steps S1001 to S1009 is performed.
In step SS1001, after the control unit 1 stops the constant current control, the voltage Vun of the battery 3b is compared with the average voltage VaVg + the first threshold value Vs1 or the average voltage VaVg−the first threshold value Vs1.

  When VaVg + Vs1 <Vun or VaVg−Vs1> Vun (Yes), the process proceeds to step S1002. When VaVg + Vs1 <Vun or VaVg−Vs1> Vun is not satisfied (No), the process proceeds to step S1001 and the constant current control is stopped.

For example, when the polarization relaxes at time t5 in FIG. 11A and the voltage Vun becomes VaVg−Vs1 at time t5, the process proceeds to step S1002 to perform constant current control.
In step S1001 of this example, the comparison is performed using the voltage Vun of the battery 3b, but the voltage Vup of the battery 3a may be used.

In step S1002, the control unit 1 obtains the current average value VaVg2 = (Vup + Vun) / 2.
In step S1003, the control unit 1 obtains a difference ΔV = VaVg2−Vun between the average value VaVg2 and the voltage Vun of the battery 3b.

  In steps S1004 to S1006, the control unit 1 performs the calculation shown in Expression 2 to obtain the PWM value. In this example, PWM value = Previous PWM value + (ΔV × coefficient k0) is obtained in step S1004, PWM value = PWM value + (previous ΔV × coefficient k1) is obtained in step S1005, and PWM value = step S1006. PWM value + (previous time ΔV × coefficient k2) is obtained. In this example, the PWM value is obtained using steps S1004 to S1006, but is not limited thereto.

  In step S1007, the control unit 1 performs PWM control using the PWM value obtained in steps S1004 to S1006, and performs constant voltage control. Refer to times t5 to t6 in FIGS.

  In step S1008, the control unit 1 determines whether or not the current value is smaller than the current value Is. If the current value is equal to or greater than the current value Is (Yes), the process proceeds to step S1002. If the current value is smaller than the current value Is (No), the process proceeds to step S1009 to stop PWM control (constant voltage control). For example, see FIGS.

In step S1009, the control unit 1 stops the PWM control and proceeds to step S1001.
As shown in FIGS. 12A and 12B, after the cross control, the constant current control may be performed from t4 in FIG. 12 when the voltages of the battery 3a and the battery 3b coincide with each other due to relaxation of the internal resistance.

In the third embodiment, when the shift at the time of relaxation of the internal resistance is small, the cell balance processing time can be made shorter than in the first and second embodiments even if constant voltage control is used.
The present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention.

1 control unit,
2 storage unit,
3a, 3b, 3c, 3d battery,
4a, 4b, 4c, 4d voltage measurement unit,
5a, 5b, 5c, 5d Current measuring unit,
L1, L2, L3 coils,
401 adjustment voltage calculation unit,
402 target voltage calculator,
403 pulse width modulator,
SW1, SW2, SW3, SW4, SW5, SW6, SW7 switch,

Claims (6)

An assembled battery in which a first battery and a second battery are connected in series;
A coil having one terminal connected to the negative terminal of the first battery and the positive terminal of the second battery;
A first switch connected between the positive terminal of the first battery and the other terminal of the coil;
A second switch connected between the negative terminal of the second battery and the other terminal of the coil;
A voltage measuring unit for measuring voltages of the first battery and the second battery;
A current measuring unit that measures currents of the first battery and the second battery;
A pulse width modulation unit that executes a pulse width modulation process for performing constant current control by controlling opening and closing of the first switch and the second switch;
A first adjustment voltage that is a difference between a start voltage of the first battery before the start of the pulse width modulation process and a voltage of the first battery after a predetermined time has elapsed; and An adjustment voltage calculation unit for obtaining a second adjustment voltage that is a difference between the start voltage of the second battery before the start and the voltage of the second battery after the lapse of the determined time;
An average voltage is obtained from an average of the voltage of the first battery and the voltage of the second battery, and the first target voltage of the first battery is determined using the average voltage and the adjustment voltage of the first battery. A target voltage calculation unit for obtaining a second target voltage of the second battery using the average voltage and the adjustment voltage of the second battery;
The pulse width modulator is
When the voltage of the first battery becomes the first target voltage or when the voltage of the second battery becomes the second target voltage, the pulse width modulation process for performing the constant current control Stop certain cross control,
A value obtained by subtracting a first threshold value from the average voltage and a value obtained by adding the first threshold value to the average voltage, which is smaller than a first range determined by the first target voltage and the second target voltage. The determined second range is shifted to equalization correction control which is a pulse width modulation process for performing constant current control so that the voltage of the first battery or the voltage of the second battery does not exceed,
When the voltage of the first battery or the voltage of the second battery falls within a range in which the pulse width modulation process including the average voltage is stopped, the pulse width modulation process for performing the equalization correction control is stopped. ,
A battery charger characterized by that. An assembled battery in which a first battery and a second battery are connected in series;
A coil having one terminal connected to the negative terminal of the first battery and the positive terminal of the second battery;
A first switch connected between the positive terminal of the first battery and the other terminal of the coil;
A second switch connected between the negative terminal of the second battery and the other terminal of the coil;
A voltage measuring unit for measuring voltages of the first battery and the second battery;
A current measuring unit that measures currents of the first battery and the second battery;
A pulse width modulation unit that executes a pulse width modulation process for performing constant current control by controlling opening and closing of the first switch and the second switch;
A first adjustment voltage that is a difference between a start voltage of the first battery before the start of the pulse width modulation process and a voltage of the first battery after a predetermined time has elapsed; and An adjustment voltage calculation unit for obtaining a second adjustment voltage that is a difference between the start voltage of the second battery before the start and the voltage of the second battery after the lapse of the determined time;
An average voltage is obtained from an average of the voltage of the first battery and the voltage of the second battery, and the first target voltage of the first battery is determined using the average voltage and the adjustment voltage of the first battery. A target voltage calculation unit for obtaining a second target voltage of the second battery using the average voltage and the adjustment voltage of the second battery;
The pulse width modulator is
When the voltage of the first battery becomes the first target voltage or when the voltage of the second battery becomes the second target voltage, the pulse width modulation process for performing the constant current control Stop certain cross control,
The voltage of the first battery or the voltage of the second battery is a value obtained by subtracting the first correction voltage from the first target voltage or a value obtained by adding the first correction voltage to the second target voltage. When it becomes, it shifts to the second cross control for performing constant current control,
When the voltage of the first battery is in a range including a third target voltage or the voltage of the second battery is in a range including a fourth target voltage, the second cross control is performed. Stop the pulse width modulation process,
A battery charger characterized by that. An assembled battery in which a first battery and a second battery are connected in series;
A coil having one terminal connected to the negative terminal of the first battery and the positive terminal of the second battery;
A first switch connected between the positive terminal of the first battery and the other terminal of the coil;
A second switch connected between the negative terminal of the second battery and the other terminal of the coil;
A voltage measuring unit for measuring voltages of the first battery and the second battery;
A current measuring unit that measures currents of the first battery and the second battery;
A pulse width modulation unit that executes a pulse width modulation process for performing constant current control by controlling opening and closing of the first switch and the second switch;
A first adjustment voltage that is a difference between a start voltage of the first battery before the start of the pulse width modulation process and a voltage of the first battery after a predetermined time has elapsed; and An adjustment voltage calculation unit for obtaining a second adjustment voltage that is a difference between the start voltage of the second battery before the start and the voltage of the second battery after the lapse of the determined time;
An average voltage is obtained from an average of the voltage of the first battery and the voltage of the second battery, and the first target voltage of the first battery is determined using the average voltage and the adjustment voltage of the first battery. A target voltage calculation unit for obtaining a second target voltage of the second battery using the average voltage and the adjustment voltage of the second battery;
The pulse width modulator is
When the voltage of the first battery becomes the first target voltage or when the voltage of the second battery becomes the second target voltage, the pulse width modulation process for performing the constant current control Stop certain cross control,
A value obtained by subtracting a first threshold value from the average voltage and a value obtained by adding the first threshold value to the average voltage, which is smaller than a first range determined by the first target voltage and the second target voltage. When the voltage of the first battery or the voltage of the second battery exceeds the determined second range, the process shifts to a pulse width modulation process for performing constant voltage control so as not to exceed the second range. ,
Stopping the pulse width modulation process for performing the constant voltage control when the current is smaller than a predetermined current value;
A battery charger characterized by that. A coil having one terminal connected to the negative terminal of the first battery and the positive terminal of the second battery, and a first terminal connected between the positive terminal of the first battery and the other terminal of the coil. 1 switch, a second switch connected between the negative terminal of the second battery and the other terminal of the coil, and the respective voltages of the first battery and the second battery are measured. A voltage measuring unit; a current measuring unit for measuring a current flowing through the assembled battery and the coil; and a pulse width modulation process for performing constant current control by controlling opening and closing of the first switch and the second switch. A voltage equalization method for a cell balance circuit, comprising:
The control unit
The first adjustment voltage, which is the difference between the start voltage of the first battery before the start of the pulse width modulation process and the voltage of the first battery after a predetermined time has elapsed, and the pulse width modulation process A second adjustment voltage that is a difference between a start voltage of the second battery before the start of the second battery and a voltage of the second battery after the determined time has elapsed,
An average voltage is obtained from the average of the voltage of the first battery and the voltage of the second battery,
The first target voltage of the first battery is obtained using the average voltage and the adjustment voltage of the first battery, and the second battery is adjusted using the average voltage and the adjustment voltage of the second battery. Find the second target voltage,
When the voltage of the first battery becomes the first target voltage or when the voltage of the second battery becomes the second target voltage, the pulse width modulation process for performing the constant current control Stop certain cross control,
A value obtained by subtracting a first threshold value from the average voltage and a value obtained by adding the first threshold value to the average voltage, which is smaller than a first range determined by the first target voltage and the second target voltage. The determined second range is shifted to equalization correction control which is a pulse width modulation process for performing constant current control so that the voltage of the first battery or the voltage of the second battery does not exceed,
Stopping the pulse width modulation processing for performing the equalization correction control when the voltage of the first battery or the voltage of the second battery is in a range in which the pulse width modulation processing including the average voltage is stopped;
The voltage equalization method characterized by the above-mentioned. A coil having one terminal connected to the negative terminal of the first battery and the positive terminal of the second battery, and a first terminal connected between the positive terminal of the first battery and the other terminal of the coil. 1 switch, a second switch connected between the negative terminal of the second battery and the other terminal of the coil, and the respective voltages of the first battery and the second battery are measured. A voltage measuring unit; a current measuring unit for measuring a current flowing through the assembled battery and the coil; and a pulse width modulation process for performing constant current control by controlling opening and closing of the first switch and the second switch. A voltage equalization method for a cell balance circuit, comprising:
The control unit
The first adjustment voltage, which is the difference between the start voltage of the first battery before the start of the pulse width modulation process and the voltage of the first battery after a predetermined time has elapsed, and the pulse width modulation process A second adjustment voltage that is a difference between a start voltage of the second battery before the start of the second battery and a voltage of the second battery after the determined time has elapsed,
An average voltage is obtained from the average of the voltage of the first battery and the voltage of the second battery,
The first target voltage of the first battery is obtained using the average voltage and the adjustment voltage of the first battery, and the second battery is adjusted using the average voltage and the adjustment voltage of the second battery. Find the second target voltage,
When the voltage of the first battery becomes the first target voltage or when the voltage of the second battery becomes the second target voltage, the pulse width modulation process for performing the constant current control Stop certain cross control,
The voltage of the first battery or the voltage of the second battery is a value obtained by subtracting the first correction voltage from the first target voltage or a value obtained by adding the first correction voltage to the second target voltage. When it becomes, it shifts to the second cross control for performing constant current control,
When the voltage of the first battery is in a range including a third target voltage or the voltage of the second battery is in a range including a fourth target voltage, the second cross control is performed. Stop the pulse width modulation process,
The voltage equalization method characterized by the above-mentioned. A coil having one terminal connected to the negative terminal of the first battery and the positive terminal of the second battery, and a first terminal connected between the positive terminal of the first battery and the other terminal of the coil. 1 switch, a second switch connected between the negative terminal of the second battery and the other terminal of the coil, and the respective voltages of the first battery and the second battery are measured. A voltage measuring unit; a current measuring unit for measuring a current flowing through the assembled battery and the coil; and a pulse width modulation process for performing constant current control by controlling opening and closing of the first switch and the second switch. A voltage equalization method for a cell balance circuit, comprising:
The control unit
The first adjustment voltage, which is the difference between the start voltage of the first battery before the start of the pulse width modulation process and the voltage of the first battery after a predetermined time has elapsed, and the pulse width modulation process A second adjustment voltage that is a difference between a start voltage of the second battery before the start of the second battery and a voltage of the second battery after the determined time has elapsed,
An average voltage is obtained from the average of the voltage of the first battery and the voltage of the second battery,
The first target voltage of the first battery is obtained using the average voltage and the adjustment voltage of the first battery, and the second battery is adjusted using the average voltage and the adjustment voltage of the second battery. Find the second target voltage,
When the voltage of the first battery becomes the first target voltage or when the voltage of the second battery becomes the second target voltage, the pulse width modulation process for performing the constant current control Stop certain cross control,
A value obtained by subtracting a first threshold value from the average voltage and a value obtained by adding the first threshold value to the average voltage, which is smaller than a first range determined by the first target voltage and the second target voltage. When the voltage of the first battery or the voltage of the second battery exceeds the determined second range, the process shifts to a pulse width modulation process for performing constant voltage control so as not to exceed the second range. ,
Stopping the pulse width modulation process for performing the constant voltage control when the current is smaller than a predetermined current value;
The voltage equalization method characterized by the above-mentioned.

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