JP5618575B2 - Storage battery evaluation apparatus and method - Google Patents

Description

  The present invention relates to a storage battery evaluation apparatus and method, and more particularly to a storage battery evaluation apparatus and method for determining an internal state such as secular change and charge amount of a secondary battery used in a power storage apparatus.

  When operating a storage battery system, in order to operate the system normally, it is necessary to periodically replace a storage battery whose life is deteriorated by repeated charging and discharging. However, since the degree of life deterioration of each storage battery varies depending on the usage status, if the batteries that have passed for a certain period of time are replaced uniformly, it will be replaced with a normal one, which is very uneconomical. Therefore, various methods for determining the life deterioration degree of the storage battery have been proposed.

  In order to grasp the internal state of the secondary battery over time, such as the state of charge (SOC), the impedance is measured by applying an AC voltage to the battery from the outside, and the battery is determined from the change in impedance with respect to the change in AC frequency. Has been proposed (see Patent Document 1).

  Further, a method for determining the internal state of a battery using a pulsation rate of a current generated on the DC side of a single-phase power storage PCS has been proposed (see Patent Document 2).

Special table 2007-506952 gazette JP 2010-154657 A

  However, the former method has a problem in that cost is increased because an externally variable frequency AC power supply is required.

  In the latter method, since the frequency is relatively low, twice the power supply frequency, there is a problem that it is difficult to detect when the resistance change is small.

  The present invention has been made in view of such problems, and the object of the present invention is to measure pulsations generated in the DC side current of a single-phase power storage device with respect to current ripples of various frequency components. It is an object of the present invention to provide a method and apparatus for accurately determining a wider range of changes in the internal state of a battery.

In order to solve the above-mentioned problem, the invention described in claim 1 is a storage battery evaluation device for determining an internal resistance of a storage battery used in a single-phase power storage AC / DC converter, Inverter control means for changing the switching frequency of the inverter to a predetermined frequency, current detection means for detecting current flowing into the storage battery, and a plurality of current values detected by the current detection means received from the inverter control means each ripple component for the frequency, the separated in DC component, pulsation rate and pulsation ratio calculating means for calculating for the plurality of frequencies is a ratio of the DC component of the ripple component, and the pulsation rate of the plurality of each frequency accumulator pulsation rate associated with the internal resistance of - a storage means for the internal resistance corresponding data are stored, the plurality calculated by the pulsation ratio calculating means Of the pulsation rate for each frequency, and the pulsation rate of the largest frequency change of the pulsation rate, read before Symbol ripple factor from the storage means a change of the pulsation rate corresponding to the largest frequency - and the internal resistance corresponding data the by matching, characterized in that an internal state determining means for determining an internal state of said electrical storage battery.
Invention of Claim 2 is a storage battery evaluation apparatus which determines the internal resistance of the storage battery used for a single phase electric power storage AC / DC converter, Comprising: The switching frequency of the inverter of the said single phase electric power storage AC / DC converter is made into predetermined frequency A settable inverter control means, a current detection means for detecting a current flowing into the storage battery, and a current value detected by the current detection means for the predetermined frequency is separated into a ripple component and a DC component, and each ripple Pulsation rate calculation means for calculating a pulsation rate that is a ratio of the DC component to the predetermined frequency with respect to the predetermined frequency, and pulsation rate-internal resistance correspondence data relating the pulsation rate for each predetermined frequency and the internal resistance of the storage battery Stored in the storage means, the pulsation rate of the predetermined frequency calculated by the pulsation rate calculating means, and the storage means corresponding to the predetermined frequency. The internal state determination means for determining the internal state of the storage battery by collating the pulsation rate-internal resistance correspondence data, and the inverter control means, as the internal resistance of the storage battery increases, The switching frequency is set to a lower predetermined frequency.

According to a third aspect of the present invention, in the storage battery evaluation apparatus according to the first or second aspect , the pulsation rate calculating means calculates a pulsation rate that is twice the power supply frequency, 1 kHz, 10 kHz, and the storage means is The pulsation rate-internal resistance correspondence data is stored for a pulsation rate of 2 kHz, 1 kHz, and 10 kHz of the power supply frequency.

A fourth aspect of the present invention is the storage battery evaluation apparatus according to any one of the first to third aspects, wherein the inverter control means is a multiplexed power storage in which a plurality of single-phase power storage AC / DC converters are connected in series. Including means for selectively changing the switching frequency of each inverter of each single-phase power storage AC / DC converter of the AC / DC converter, and the current detection means calculates the current flowing into the storage battery of each single-phase power storage AC / DC converter. A means for selectively detecting is included.

The invention according to claim 5 is a storage battery evaluation method for determining the internal resistance of a storage battery used in a single-phase power storage AC / DC converter, wherein the switching frequency of the inverter of the single-phase power storage AC / DC converter is set to a plurality of frequencies. an inverter control step that can be set, and a current detection step of detecting a current flowing into the battery, for the plurality of frequencies, to separate the current value detected by the current detecting step ripple component, the DC component, the ripple pulsation ratio calculating step of the ripple factor calculated with the plurality of frequencies is a ratio of the frequency for the DC component, the plurality of pulse rate and pulse rate associated with the internal resistance of the battery at each frequency - the internal resistance corresponding from the storage means in which data is stored, the ripple factor corresponding to said plurality of frequencies - the step of reading the internal resistance corresponding data, the ripple factor Starring Among steps previously calculated by the pulsation rate of each of the plurality of frequencies, said the change of the pulsation rate of the largest frequency of the pulsation rate, read from said storage means said change in the pulsation rate corresponding to the largest frequency pulsations rate - by checking the internal resistance corresponding data, and having an internal state determining step of determining an internal state of said electrical storage battery.
The invention according to claim 6 is a storage battery evaluation method for determining the internal resistance of a storage battery used in a single-phase power storage AC / DC converter, wherein the switching frequency of the inverter of the single-phase power storage AC / DC converter is set to a predetermined frequency. A settable inverter control step, a current detection step for detecting a current flowing into the storage battery, and a current value detected in the current detection step for the predetermined frequency is separated into a ripple component and a DC component, and each ripple A pulsation rate calculation step for calculating a pulsation rate that is a ratio of a minute to a DC component for the predetermined frequency, and a pulsation rate-internal resistance correspondence data that associates the pulsation rate for each predetermined frequency with the internal resistance of the storage battery Reading the pulsation rate-internal resistance correspondence data corresponding to the predetermined frequency from the storage means storing the pulsation rate, The internal state of the storage battery is determined by comparing the pulsation rate of the predetermined frequency calculated in the step with the pulsation rate-internal resistance correspondence data read from the storage unit corresponding to the predetermined frequency. A state determination step, wherein the inverter control step sets the switching frequency to a lower predetermined frequency as the internal resistance of the storage battery increases.

According to a seventh aspect of the present invention, in the storage battery evaluation apparatus according to the fifth or sixth aspect , the pulsation rate calculating step calculates a pulsation rate of twice a power supply frequency, 1 kHz, 10 kHz, and the storage means The pulsation rate-internal resistance correspondence data is stored for a pulsation rate of 2 kHz, 1 kHz, and 10 kHz of the power supply frequency.

According to an eighth aspect of the present invention, in the storage battery evaluation apparatus according to any of the fifth to seventh aspects, the inverter control step is a multiplexed power storage in which a plurality of single-phase power storage AC / DC converters are connected in series. A step of selectively changing a switching frequency of each inverter of each single-phase power storage AC / DC converter of the AC / DC converter, and the current detecting step is configured to calculate a current flowing into a storage battery of each single-phase power storage AC / DC converter. A step of selectively detecting.

  The present invention makes it possible to accurately determine a wider range of changes in the internal state of a battery by measuring pulsations generated in the DC side current of a single-phase power storage device with respect to current ripples of various frequency components. There is an effect.

It is a figure which shows the main circuit structure of the storage battery evaluation apparatus which concerns on embodiment of this invention. It is a figure which shows the detection circuit structure of the impedance detection means which concerns on embodiment of this invention. It is a figure which shows the example of a main circuit structure of single phase power storage PCS. It is a figure which shows the circuit structure used for simulation. (A), (c), be a diagram showing a (e) is a constant internal resistance r _i in 10 m [Omega, the simulation results of the direct current I _dc2 when the switching frequency f _sw is changed 10 kHz, 5 kHz, and 2kHz , (B), (d), and (f) are diagrams showing simulation results of the direct current I _dc2 when the internal resistance r _i is constant at 50 mΩ and the switching frequency f _sw is changed to 10 kHz, 5 kHz, and 2 kHz. is there. (A) ~ (c) is kept constant at 1000mΩ the internal resistance r _i In this circuit configuration, the switching frequency f _sw 10 kHz, 5 kHz, a diagram showing a simulation result of the DC current I _dc2 when changing the 2kHz is there. It is a figure which shows the circuit structure which extracts a switching ripple and a rectification ripple from a direct current using a high pass filter (HPF) and a band pass filter (BPF). It is a figure which shows the relationship between the internal resistance of a simulation result, and a part for a ripple. It is a diagram showing a frequency suitable for measuring ripple effective value for each size of the internal resistance r _i.

  The change in the current ripple with respect to the change in the internal impedance of the battery is suitable for a small impedance change because it changes even with a small impedance for a high frequency ripple, but when the impedance increases, the high frequency ripple cannot be observed. .

  On the other hand, the low frequency ripple is insensitive to the change in the internal impedance of the battery, but the change can be observed even when the impedance changes greatly. Therefore, by estimating the internal state with current ripples of various frequency components, it is possible to measure a wider range of impedance changes with higher accuracy.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In FIG. 1, the main circuit structure of the storage battery evaluation apparatus which concerns on embodiment of this invention is shown. FIG. 2 shows a detection circuit configuration of the impedance detection means according to the embodiment of the present invention. The storage battery evaluation apparatus includes inverter control means 104 and impedance measurement means 105.

  The internal state of the storage battery is determined by the inverter control means 104 changing the switching frequency of the PCS 102 and the impedance measuring means 105 calculating the pulsation rate for each switching frequency.

For the full-wave rectification ripple extraction means 202, for example, a BPF with a center frequency of 100 Hz is used, and for the switching ripple extraction means 203, for example, an HPF with a cutoff frequency of 1 kHz or 10 kHz is used. Information on the switching frequency f _sw is acquired from the inverter control means 107. The reason why the center frequency of the BPF is set to 100 Hz is to make the power frequency of the AC power source 101 twice, and in this case, a 50 Hz system is assumed. That is, if the AC power supply 101 is a 60 Hz system, the center frequency of the BPF is 120 Hz.

  The impedance measuring means 105 separates and extracts the rectification ripple and the switching ripple by the full-wave rectification ripple extraction means 202 and the switching ripple extraction means 203, and extracts the DC component by the average value calculation means 204. Then, the pulsation rate, which is the ratio of each ripple to the DC component, is calculated for each of the rectification ripple, 1 kHz, and 10 kHz switching ripple.

Regarding the relationship between the pulsation rate and the internal resistance, a relationship corresponding to the switching frequency is recorded in advance in the database, and the recorded pulsation rate-internal resistance relationship and the newly measured pulsation rate are used as the internal state determination unit 206. The internal resistance and internal state (SOC and aging degradation) are estimated by comparing the above. That is, the internal state determination unit 206 selects a pulsation rate suitable for the rectification ripple, 1 kHz switching ripple, or 10 kHz switching ripple according to the switching frequency f _sw and records corresponding to the pulsation rate. The internal resistance and internal state (SOC and aging) are estimated from the measured pulsation rate-internal resistance database.

  In addition, it cannot be overemphasized that this storage battery evaluation apparatus is applicable similarly to each stage of the low voltage battery module multiplexing PCS.

  Hereinafter, the operation principle of the present invention will be described in detail.

  The DC-side current of the single-phase power storage PCS includes a ripple of a frequency twice the power supply frequency by single-phase full-wave rectification and a harmonic ripple by switching. At both ends of the smoothing capacitor C, a voltage ripple having a frequency twice as large as the power supply frequency is generated by this current ripple, and as a result, a ripple corresponding to twice the power supply frequency is generated in the current flowing into the storage battery. . Further, when the smoothing reactor is not included or the impedance of the smoothing reactor is small, a high-frequency current component due to switching is also included. Further, when the switching frequency is changed, ripple components having various frequencies can be obtained.

  Thereby, a change in internal resistance due to a change in the state of the battery can be measured by ripples of various frequencies, and the internal state of the battery can be accurately determined over a wide range. In addition, since the measurement is simply performed by changing the switching frequency of the inverter with an existing PCS, it can be realized at a lower cost than the conventional method in which a variable frequency AC power source needs to be added.

  In the present invention, in the invention in which only the change in the ratio of the ripple current to the DC component flowing in the storage battery is focused and the life deterioration degree of the battery is simply determined, the ripple component having twice the frequency of the power supply frequency and the harmonic ripple component due to switching. Both are used.

  FIG. 3 shows a main circuit configuration example of the single-phase power storage PCS. The current Idco flowing from the PCS 102 includes a ripple of a frequency twice the power supply frequency by single-phase full-wave rectification and a harmonic ripple by switching. At both ends of the smoothing capacitor C, a voltage ripple having a frequency twice as large as the power supply frequency is generated due to this current ripple, and as a result, a ripple corresponding to twice the power supply frequency is generated in the current flowing into the storage battery 103. Become. Further, when the smoothing reactor is not included or the impedance of the smoothing reactor is small, the current flowing into the storage battery 103 includes a high-frequency current component due to switching.

FIG. 4 shows a circuit configuration used for the simulation. In the case where there is a reactor, the high-frequency ripple is removed by the low-pass filter effect by the smoothing capacitor C and the internal resistance r _i, so that it is difficult to observe, so the low voltage battery multiplexed PCS that can omit the DC reactor shown in FIG. A simulation was performed. Multiplexed PCS inverters 102 a and 102 b in which two storage battery modules are connected in series are connected to an AC power source 101 via a slidac 106. The variable resistor 108 is used to simulate the internal resistance of the storage battery. Further, the bumpers 107a to 107c are provided on the AC side and the DC side, respectively.

FIGS. 5A to 5F show simulation results of the direct current I _dc2 when the internal resistance r _i is constant at 10 mΩ and 50 mΩ and the switching frequency f _sw is changed to 10 kHz, 5 kHz, and 2 kHz in this circuit configuration. Indicates. It is confirmed that the simulation result agrees well with the experimental result of the prototype.

From this result, it can be seen that when f _sw is lowered, the switching ripple is increased, and when the internal resistance is increased, the switching ripple is attenuated.

FIGS. 6A to 6C show simulation results of the direct current I _dc when the switching frequency f _sw is constant at 2 kHz and the internal resistance r _i is changed to 100 mΩ, 500 mΩ, and 1000 mΩ in this circuit configuration. . The change in the internal resistance r _i shown in FIG. 5 hardly changes the pulsation at 100 Hz. However, when the internal resistance r _i is increased to 1000 mΩ, the pulsation at 100 Hz caused by rectification also attenuates as the resistance increases. I understand that Therefore, when the resistance is large, the internal state of the storage battery can be accurately known by measuring a low frequency, for example, a 100 Hz component that is a ripple due to rectification.

Thus, there is a correlation between the internal resistance, the ripple frequency, and the magnitude of the ripple current. As shown in FIG. 7, the simulated DC current I _dc is measured by a measurement circuit through a filter circuit of a high pass filter (HPF) and a band pass filter (BPF), and the change in the effective value of the switching ripple and the effective value of the rectifying ripple is measured. It was measured. The HPF had a cutoff frequency of 1000 Hz, and the BPF center frequency was 100 Hz.

FIG. 8 shows the relationship between the internal resistance and the ripple amount in the simulation result. From this relationship, the internal resistance r _i can be accurately estimated over a wide range by measuring the ripple effective value by changing the switching frequency. That is, by measuring the ripple RMS at high switching frequency at low internal resistance r _i, determines uniquely the internal resistance r _i from the ripple RMS ripple effective at low switching frequency at higher internal resistance r _i By measuring the value, the internal resistance r _i is uniquely determined from the ripple effective value.

FIG. 9 shows frequencies suitable for measuring the ripple effective value for each magnitude of the internal resistance r _i . r _i> 200 milliohms At rectification ripple, 200mΩ ≧ r _i ≧ 8mΩ the 1kHz switching frequency f _sw, 30 m [Omega]> is to measure respectively the switching frequency f _sw of 10kHz at r _i said appropriate.

  Thus, by measuring the ripple effective value by changing the switching frequency, the internal resistance can be accurately estimated over a wide range according to the change in the internal state of the storage battery. Therefore, for example, when the internal resistance before aging deterioration is small, the aging change can be detected early by increasing the switching frequency and observing the change in the ripple effective value. In addition, when the internal resistance increases over time, the change can be accurately estimated by lowering the switching frequency and observing the ripple effective value.

101 AC power supply 102 PCS
102a, 102b Inverter 103 Storage battery 104 Inverter control means 105 Impedance measurement means 106 Slidac 107a-107b Anti-shock 108 Variable resistance 109 Storage battery evaluation device

Claims (8)

A storage battery evaluation device for determining the internal resistance of a storage battery used in a single-phase power storage AC / DC converter,
Inverter control means capable of setting the switching frequency of the inverter of the single-phase power storage AC / DC converter to a plurality of frequencies;
Current detecting means for detecting current flowing into the storage battery;
For the plurality of frequencies, the ripple component of the current value detected by said current detecting means, to separate the DC component, the pulsation ratio calculating means for calculating a ripple factor is a ratio for the DC component of the ripple component for the plurality of frequencies When,
Storage means storing pulsation rate-internal resistance correspondence data in which the pulsation rate for each of the plurality of frequencies and the internal resistance of the storage battery are related;
Among the pulsation rates for each of the plurality of frequencies calculated by the pulsation rate calculating means, the pulsation rate of the frequency with the largest change in the pulsation rate and the storage means corresponding to the frequency with the largest change in the pulsation rate read before Symbol ripple factor - by matching the internal resistance corresponding data, battery evaluation apparatus characterized by comprising an internal state determining means for determining an internal state of said electrical storage battery. A storage battery evaluation device for determining the internal resistance of a storage battery used in a single-phase power storage AC / DC converter,
  Inverter control means capable of setting the switching frequency of the inverter of the single-phase power storage AC / DC converter to a predetermined frequency;
  Current detecting means for detecting current flowing into the storage battery;
  With respect to the predetermined frequency, the current value detected by the current detection means is separated into a ripple component and a direct current component, and a pulsation rate calculating unit that calculates a pulsation rate that is a ratio of each ripple to the direct current component with respect to the predetermined frequency. When,
  Storage means for storing pulsation rate-internal resistance correspondence data in which the pulsation rate for each predetermined frequency and the internal resistance of the storage battery are related;
  By comparing the pulsation rate of the predetermined frequency calculated by the pulsation rate calculating means with the pulsation rate-internal resistance correspondence data read from the storage means corresponding to the predetermined frequency, the internal state of the storage battery Internal state determination means for determining
And the inverter control means sets the switching frequency to a lower predetermined frequency as the internal resistance of the storage battery increases. The pulsation rate calculating means calculates a pulsation rate of 2 times the power supply frequency, 1 kHz, 10 kHz,
  3. The storage battery evaluation apparatus according to claim 1, wherein the storage unit stores the pulsation rate-internal resistance correspondence data for a pulsation rate of twice a power supply frequency, 1 kHz, and 10 kHz. The inverter control means selectively changes the switching frequency of each inverter of each single-phase power storage AC / DC converter of a multiplexed power storage AC / DC converter in which a plurality of single-phase power storage AC / DC converters are connected in series. Including
  The storage battery evaluation apparatus according to claim 1, wherein the current detection unit includes a unit that selectively detects a current flowing into the storage battery of each single-phase power storage AC / DC converter. A storage battery evaluation method for determining the internal resistance of a storage battery used in a single-phase power storage AC / DC converter,
  An inverter control step capable of setting the switching frequency of the inverter of the single-phase power storage AC / DC converter to a plurality of frequencies;
  A current detection step for detecting a current flowing into the storage battery;
  For the plurality of frequencies, the current value detected in the current detection step is separated into ripples and DC components, and a pulsation rate calculation step for calculating a pulsation rate that is a ratio of each ripple to the DC component for the plurality of frequencies. When,
  The pulsation rate-internal resistance correspondence data corresponding to the plurality of frequencies is stored from storage means storing pulsation rate-internal resistance correspondence data in which the pulsation rate for each of the plurality of frequencies is associated with the internal resistance of the storage battery. A step to read,
  Of the pulsation rates for each of the plurality of frequencies calculated in the pulsation rate calculating step, the storage means corresponding to the pulsation rate having the largest change in the pulsation rate and the frequency having the largest change in the pulsation rate An internal state determination step of determining the internal state of the storage battery by comparing the pulsation rate-internal resistance correspondence data read from
The storage battery evaluation method characterized by having. A storage battery evaluation method for determining the internal resistance of a storage battery used in a single-phase power storage AC / DC converter,
  An inverter control step capable of setting a switching frequency of the inverter of the single-phase power storage AC / DC converter to a predetermined frequency;
  A current detection step for detecting a current flowing into the storage battery;
  For the predetermined frequency, the current value detected in the current detection step is separated into ripples and direct current components, and a pulsation rate calculation step for calculating a pulsation rate that is a ratio of each ripple to the direct current component for the predetermined frequency When,
  The pulsation rate-internal resistance correspondence data corresponding to the predetermined frequency is stored from storage means storing pulsation rate-internal resistance correspondence data in which the pulsation rate for each predetermined frequency is associated with the internal resistance of the storage battery. A step to read,
  By comparing the pulsation rate of the predetermined frequency calculated in the pulsation rate calculating step with the pulsation rate-internal resistance correspondence data read from the storage means corresponding to the predetermined frequency, the internal state of the storage battery An internal state determination step for determining
And the inverter control step sets the switching frequency to a lower predetermined frequency as the internal resistance of the storage battery increases. The pulsation rate calculating step calculates a pulsation rate of 2 times the power supply frequency, 1 kHz, 10 kHz,
  The storage battery evaluation method according to claim 5 or 6, wherein the storage means stores the pulsation rate-internal resistance correspondence data for a pulsation rate of 2 kHz, 1 kHz, and 10 kHz. The inverter control step selectively changes a switching frequency of each inverter of each single-phase power storage AC / DC converter of a multiplexed power storage AC / DC converter in which a plurality of single-phase power storage AC / DC converters are connected in series. Including
  The storage battery evaluation method according to any one of claims 5 to 7, wherein the current detection step includes a step of selectively detecting a current flowing into the storage battery of each of the single-phase power storage AC / DC converters.

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