JP2013228244A - Secondary battery system having function for monitoring battery residual capacity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery system capable of highly accurately monitoring battery residual capacity, without disposing expensive current detecting means such as a shunt resistor and a Hall CT inside a battery pack.SOLUTION: In a secondary battery system, a battery pack 1 is connected to an AC power supply system 10 through a DC filter capacitor 2, a voltage type AC/DC power converter 3 and an AC filter reactor 4. The AC/DC power converter 3 includes a power supply side current detector 5 and a power supply side voltage detector 6 that continuously monitor the AC power supply system 10 and obtain a current value and a voltage value of the system 10, and a control unit 7 for performing current control on the basis of the obtained detection values, for current control for the AC power supply system 10 side. The control unit 7 is provided with a monitoring unit 71 for monitoring charging and discharging power and battery residual capacity of the battery pack 1. The detection values of the power supply side current detector 5 and the power supply side voltage detector 6 are inputted to a calculation unit 72 provided in the monitoring unit 71.

Description

  Embodiments of the present invention relate to a secondary battery system directly connected to an AC / DC power converter, and particularly to a secondary battery system having a function of monitoring the remaining battery level of a battery pack using the AC / DC power converter. Related.

  With the high performance and large capacity of secondary batteries, the management of charge / discharge energy is becoming important. In particular, it is difficult to obtain the remaining battery level from the battery voltage in a secondary battery that has a long battery voltage range relative to the remaining battery level. There are many.

  In the current battery system, the charge / discharge power amount to the secondary battery is managed by integrating the current detected by the shunt resistor or Hall CT incorporated in the secondary battery pack or module. Since these shunt resistors and Hall CTs require high accuracy, they are often expensive. On the other hand, when a current sensor with low accuracy is used, some countermeasure is required to compensate for it.

  For example, in the invention of Patent Document 1, the temperature rise is estimated from the assumed current value, the change in the element value of the secondary battery and the change in the current are derived from the temperature rise, and the derived current value is used. By repeating the operation of correcting the previously derived current value, the discharge characteristics are estimated from a small amount of data detected by a current sensor with poor detection capability.

JP 2010-223781 A

  However, when such an inexpensive current sensor with inferior capacity is used, there is a limit to the detection accuracy that can be obtained no matter how complicated the arithmetic processing is performed. Further, performing such complicated arithmetic processing increases the burden on the CPU constituting the system and is not a preferable means.

  An embodiment of the present invention is to provide a secondary battery system capable of monitoring a remaining battery level with high accuracy without providing an expensive current sensor such as a shunt resistor or Hall CT in a battery pack. .

  A secondary battery system having a battery remaining amount monitoring function according to an embodiment of the present invention is a secondary battery system in which a power converter that charges and discharges a battery pack is directly connected. Alternatively, the amount of power passing through the power converter is obtained based on the detection value obtained by the current detector, and the charge / discharge amount to the secondary battery and the battery remaining amount are calculated based on the amount of power. And

1 is a circuit diagram showing a first embodiment of the present invention. The block diagram which shows the calculating part of the battery charging / discharging amount in embodiment of this invention. The circuit diagram which shows 2nd Embodiment of this invention. The circuit diagram which shows 3rd Embodiment of this invention. The circuit diagram which shows 4th Embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a secondary battery system having a battery remaining amount monitoring function according to the present invention will be described with reference to the drawings.

[1. First Embodiment]
A first embodiment of the present invention will be described with reference to FIG. 1st Embodiment is a typical structural example in the case of charging / discharging a battery pack directly from AC power supply.

  The battery pack 1 is configured by connecting a plurality of secondary batteries in series and / or in parallel. The battery pack 1 is connected to an AC power supply system 10 via a DC filter capacitor 2, a voltage type AC / DC power converter 3 and an AC filter reactor 4. In this case, the secondary battery side of the AC / DC power converter 3 is regarded as a voltage source having a higher voltage than the AC power supply system, and charge / discharge control for the battery pack 1 is performed. That is, during charging, power is supplied from the AC power supply system 10 to the battery pack 1 while boosting, and during discharging, power is accommodated to the AC power supply system 10 while reducing the battery voltage.

  The AC / DC power converter 3 includes a power source side current detector 5 and a power source side voltage detector 6 that constantly monitor the AC power source system 10 and acquire the current value and voltage value for current control on the AC power source system 10 side. And the control part 7 which performs electric current control based on these detected values is provided. The control unit 7 is connected to the AC / DC power converter 3 via the signal line 8, and current control of the AC / DC power converter 3 is performed by a signal from the control unit 7. A battery voltage detector 9 is provided on the battery pack 1 side of the AC / DC power converter 3.

The control unit 7 is provided with a monitoring unit 71 that monitors the charge / discharge power of the battery pack 1 and the remaining battery level. Detection values of the power source side current detector 5 and the power source side voltage detector 6 are input to the arithmetic unit 72 provided in the monitoring unit 71. The computing unit 72 includes a current value that is constantly measured by the power source side current detector 5 provided in the AC / DC power converter 3 for the instantaneous power P _AC on the AC power source system 10 side, and a power source side voltage detector 6 that Calculation is performed by multiplying the measured current value. This calculation formula is shown in the following formula 1.

  In Equation 1, calculation is performed using the phase voltage and current of each of the three phases. In the case of the three-phase three-wire method, the fact that the sum of the three phases becomes zero is used to detect the current on the power source side. The device 5 may be provided with only two phases, and the power supply side voltage detector 6 may measure only two sets of line voltages. In this case, the current value of the remaining one phase can be calculated, or the phase voltage can be calculated from two sets of line voltages. In addition, when control is performed on rotating coordinates, the current and voltage are converted from stationary coordinates to rotating coordinates inside the controller, so calculations are performed on the linear and horizontal axes of the rotating coordinate system synchronized with the system voltage. May be.

  By integrating the instantaneous active power calculated by the calculation unit 72 in this manner, the amount of power on the AC side of the AC / DC power converter 3 can be calculated. In this case, in order to calculate the amount of power on the DC side to which the battery pack 1 is connected, the loss due to the AC / DC power converter 3 must be taken into account. That is, when charging the secondary battery, it is necessary to subtract the loss of the AC / DC power converter 3 from the calculated instantaneous active power.

によって計算される。ただし、式２では電力の流れは充電方向を正の値としている。 On the other hand, when power is supplied to the load or regenerated to the system, the loss of the AC / DC power converter 3 needs to be added. Therefore, the calculation unit 72 performs a calculation as shown in the following Expression 2. In this case, the charge / discharge amount to the battery pack 1 is defined as the loss of the AC / DC power converter 3 as P _LOSS .

Calculated by However, in Formula 2, the flow of electric power has a positive value in the charging direction.

Further, the loss P _LOSS is always a positive value. Received power P _AC of the time of discharge by the AC power supply system 10 side takes a negative value, but amount obtained by adding a converter loss P _LOSS to be discharged from the battery pack 1.

There are several ways to calculate the loss P _LOSS . The simplest method is that the efficiency of the AC / DC power converter 3 is assumed to be constant, and the loss P _LOSS of the AC / DC power converter 3 is always calculated by multiplying the calculated received power _PAC by a certain constant. It is a method to consider. If the loss correction by the AC / DC power converter 3 is performed more accurately, output vs. efficiency characteristic data obtained during a converter performance test or the like is tabulated and held in the control unit 7. During actual operation, the loss P _LOSS by the converter is calculated with reference to the table in the control unit 7.

An example of the calculation unit 72 is shown in FIG. In FIG. 2, 72a is the multiplier of the system voltage and the AC current, 72b is a table which records the characteristic data of the output counter rate converter, 72c subtracter subtracting the converter loss P _LOSS and reception power P _AC, 72d Is an integrator. By using such a calculation means, the loss correction by the AC / DC power converter 3 can be performed accurately by executing the expression 2 while referring to the output vs. efficiency characteristic data.

More specifically, the loss due to the AC / DC power converter 3 is divided into the following three, and calculation is performed using Equation 3.
(1) A constant amount independent of output
(2) The element is proportional to the current, such as the (fixed) voltage drop of the element.
(3) A component proportional to the square of the current, such as wiring resistance

I _{RMS in} Equation 3 is an effective value of the AC side current of the AC / DC power converter 3. _That is, R _LOSS I _RMS ² is proportional to the square of the current, V _LOSS I _RMS is proportional to the current, and P _0LOSS is constant regardless of the current. The coefficient of each term and the value of the constant term in this equation give fixed values based on the results of the performance test of the AC / DC power converter 3.

  In the method described here, the charge / discharge power amount to the battery pack 1 is obtained by integrating the instantaneous power passing through the AC / DC power converter 3. For this reason, when the detected value of the current or voltage used when calculating the instantaneous power includes an error, the error may be accumulated by the integration calculation. Means for avoiding this will be described.

  Even in the case of the battery pack 1 having a long region where the terminal voltage at no load is constant regardless of the amount of electric power that can be discharged, there are many cases in which a large voltage change is easily detected near the end of discharge and the end of charge. Therefore, when the speed at which the battery side voltage decreases during the discharging operation becomes faster or when the speed at which the battery side voltage increases during the charging operation becomes faster, While correcting the charging / discharging electric energy until then, a charging / discharging stop measure can be performed.

  That is, when the voltage on the battery pack 1 side of the AC / DC power converter 3 falls below a preset value during discharging, the charge / discharge power amount is corrected to an amount corresponding to the voltage. Even during charging, if the output voltage on the battery pack 1 side of the AC / DC power converter 3 exceeds a preset value, the charge / discharge power amount is corrected to an amount corresponding to the voltage.

  On the other hand, even if the remaining battery level is close to 100% or 0% in the calculation, if the battery side voltage does not change accordingly, it has not yet approached the end of charging or discharging. The calculated value of the charge / discharge energy at that stage is retained.

  When the AC / DC power converter 3 that charges / discharges the battery pack 1 is not operating at the end of charging or discharging, the battery side voltage of the AC / DC power converter 3 is the same as that of the battery pack 1. It becomes a value close to a load voltage (OCV: Open Circuit Voltage), and using this value, the total charge / discharge power amount to the battery pack 1 can be corrected.

  Based on the correction amount performed here, the coefficient of each term of Equation 3 used in the loss calculation in the AC / DC power converter 3 and the loss amount table in the control unit 7 of the AC / DC power converter 3 If the correction is performed, the calculation accuracy of the charge / discharge amount to the battery pack 1 can be further increased.

  As described above, according to the present embodiment, the secondary battery is charged / discharged without using a current detector such as a shunt resistor or Hall CT conventionally used for charge / discharge amount management of the battery. The charge / discharge amount to the battery pack can be detected by using a high-performance controller or voltage / current detector for current / power control that is originally provided in the AC / DC power converter that performs the above.

[2. Second Embodiment]
A second embodiment of the present invention will be described with reference to FIG. The second embodiment is suitable when there are a plurality of AC / DC power converters that charge and discharge the battery pack 1 such as a hybrid vehicle of an internal combustion engine and a secondary battery.

  In this embodiment, the electric power generated by the generator 21 is converted into direct current by the AC / DC power converter 22, and the battery pack 1 is directly connected to this portion. The direct current output from the battery pack 1 is reconverted by the AC / DC power converter 23 into alternating current having a frequency and voltage corresponding to the state of the load 24 and supplied to the load 24.

  Thus, in the present embodiment, the two AC / DC power converters 22 and 23 are connected to the battery pack 1. Therefore, the charge / discharge amount to / from the battery pack 1 is the difference between the power converted to DC by the AC / DC power converter 22 and the power reconverted to AC by the AC / DC power converter 23. Accordingly, the calculation unit 72 of the monitoring unit 71 provided in the control unit 7 of the AC / DC power converters 22 and 23 obtains the DC-side power amount of the AC / DC power converters 22 and 23 by the method according to the first embodiment, for example. Then, the charge / discharge electric energy to the battery pack 1 is calculated | required by taking the difference. Also in this case, it is not necessary to install a current sensor dedicated to the battery pack in the DC part.

[3. Third Embodiment]
A third embodiment will be described with reference to FIG. In the third embodiment, the battery pack 1 is connected to a DC power supply system 16 having different voltages via a step-up / step-down chopper 15 including a step-up reactor 12, a switching element 13, and a filter capacitor 14. In the present embodiment, the voltage of the battery pack 1 is kept low from the standpoint of insulation and the like, and the DC power supply system 16 is stepped up during discharging and stepped down during charging to accommodate power.

  The step-up / step-down chopper 15 performs current control on the low-voltage side. The step-up / down chopper 15 is provided with a current detector 5 in series with the step-up reactor 12, and the step-up / step-down chopper 15 moves up and down based on the current value obtained by the current detector 5. By controlling the chopper 15, the current control on the low voltage side is performed. On the other hand, in this embodiment, the voltage detector 9 is provided in the step-up / step-down chopper 15, and the voltage of the battery pack 1 is constantly monitored by the voltage detector 9.

  Therefore, in this embodiment, as shown in the following Expression 4, the battery can be easily obtained by multiplying the current value detected by the current detector 5 and the voltage detector 9 provided in the step-up / down chopper 15 and the voltage value. The power entering and leaving the pack 1 can be calculated. By integrating this, the charge / discharge power amount to the battery pack 1, that is, the remaining battery level can be calculated.

によって表される。式４にてＲ_BATTは電池の内部抵抗相当値で、積分の中身の第２項は電池の内部抵抗分による損失分を補正する項である。 This formula is

Represented by In Equation 4, R _BATT is a value corresponding to the internal resistance of the battery, and the second term in the integral is a term for correcting the loss due to the internal resistance of the battery.

  As described above, according to the present embodiment, it is not necessary to incorporate a current detector for accurately obtaining the charge / discharge power amount for the battery in the battery pack 1. In this embodiment, since the voltage of the battery pack 1 is constantly monitored, there is an advantage that the safety of the system is ensured.

  Even when the output of the voltage detector 9 that detects the voltage of the battery pack 1 is used only for protection in the event of an abnormality and is not incorporated in the control unit 7, the voltage value detected by the power supply side voltage detector 6 The voltage on the low voltage side of the step-up / step-down chopper 15 can be easily calculated from the modulation factor of the boost chopper 15, and the voltage value on the low voltage side can be substituted for the detected voltage value on the battery side. In this case, the modulation factor of the boost chopper 15 is constantly monitored by the control unit 7 by known means during operation of the boost value chopper 15, and the calculation unit 72 can easily obtain the modulation factor from the control unit. Can do.

  In the present embodiment, the remaining amount management of the battery may be performed by the control unit 7 of the step-up / step-down chopper 15, the charge / discharge power amount to the battery is passed to the battery pack 1, and the remaining battery amount on the battery pack 1 side is passed. Management may be performed. In this case, the current sensor on the battery pack 1 side cannot be omitted due to the operating principle of the boost chopper 15, but the battery voltage can be calculated from the power supply side voltage and the modulation factor of the boost chopper 15. The detector can be omitted.

[4. Other Embodiments]
The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  For example, as shown in FIG. 5, when the current type AC / DC power converter 17 capable of directly controlling the current on the battery pack 1 side is connected to the battery pack 1, the same method as in the first embodiment, The amount of power on the battery pack 1 side can be calculated. In this case, the charge / discharge power amount to the battery pack 1 can be obtained by the calculation unit 72 without considering the loss due to the current-type AC / DC power converter 17. For correction of the error accumulated by the integration calculation, the calculation unit 72 can use the same calculation as in the first embodiment.

  Furthermore, in each said embodiment, when an AC / DC power converter stops, charging / discharging electric energy can also be correct | amended with the open circuit voltage of a battery.

DESCRIPTION OF SYMBOLS 1 ... Battery pack 2 ... DC filter capacitor 3 ... Voltage type AC / DC power converter 4 ... AC filter capacitor 5 ... Power source side current detector 6 ... Power source side voltage detector 7 ... Control part 71 ... Monitoring part 72 ... Calculation part 8 ... Signal line 9 ... Battery voltage detector 10 ... AC power supply system 12 ... Boosting reactor 13 ... Switching element 14 ... Filter capacitor 15 ... Boosting chopper 16 ... DC power supply system 17 ... Current type AC / DC power converter

Claims (8)

A voltage-type AC / DC power converter connected to the AC power supply system; and a battery pack directly connected to the AC / DC power converter, the AC / DC power converter including a control unit for controlling a current on the power source side. In the secondary battery system
The AC / DC power converter includes a current detector that detects a current on the power supply side, and a voltage detector that detects a voltage on the power supply side,
The control unit is provided with a calculation unit that calculates a charge / discharge power amount to the battery pack based on a current value and a voltage value detected by the current detector and the voltage detector on the power source side. Secondary battery system having a function of monitoring the remaining battery power.   A plurality of AC / DC power converters that charge / discharge are connected to the battery pack, and the calculation unit calculates the charge / discharge amount to the battery pack based on the amount of power obtained by the plurality of AC / DC power converters. The secondary battery system which has the monitoring function of the battery remaining amount of Claim 1 characterized by the above-mentioned.   The battery remaining amount monitoring according to claim 1, wherein the calculation unit performs a calculation for correcting the efficiency of the AC / DC power converter when calculating the charge / discharge power amount for the battery pack. A secondary battery system having a function.   The said calculating part correct | amends charging / discharging electric energy according to this, when battery side voltage changes suddenly, The monitoring function of the remaining battery level of Claim 1 or Claim 2 characterized by the above-mentioned. Next battery system.   The said calculating part is provided with the table which recorded the parameter used for the loss calculation in a power converter, and correct | amends the said parameter when correcting charge / discharge amount, The Claim 1 or Claim 2 characterized by the above-mentioned. A secondary battery system having a function of monitoring the remaining battery capacity described in 1. A secondary battery having a step-up / step-down chopper type power converter connected to a DC power supply system and a battery pack directly connected to the power converter, the power converter including a control unit for controlling battery current. In battery systems,
The power converter includes a voltage detector that detects a voltage on the battery pack side, and a current detector that detects a current on the battery pack side,
The control unit is provided with a calculation unit for calculating a charge / discharge power amount to the battery pack based on a current value and a voltage value detected by the current detector and the voltage detector. A secondary battery system having an amount monitoring function. A secondary battery having a step-up / step-down chopper type power converter connected to a DC power supply system and a battery pack directly connected to the power converter, the power converter including a control unit for controlling battery current. In battery systems,
The power converter includes a voltage detector that detects a voltage on the power supply side, a control unit that acquires a modulation rate of the power converter, a battery pack based on the voltage from the voltage detector and the modulation rate from the control unit A secondary battery system having a battery remaining amount monitoring function, characterized in that an arithmetic unit for calculating a charge / discharge power amount is provided. A current-type AC / DC power converter connected to the AC power supply system; and a battery pack directly connected to the AC / DC power converter, the AC / DC power converter including a controller that controls a current on the battery pack side. Secondary battery system
The AC / DC power converter includes a current detector that detects a current on the battery pack side, and a voltage detector that detects a voltage on the battery pack side,
The control unit is provided with a calculation unit that calculates a charge / discharge power amount to the battery pack based on a current value and a voltage value detected by the current detector and the voltage detector on the battery pack side. A secondary battery system having a function for monitoring the remaining battery level.

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