JP7163097B2 - storage battery system - Google Patents

Description

Embodiments of the present invention relate to storage battery systems .

Conventionally, there is a storage battery system in which a number of cell batteries or assembled batteries corresponding to the amount of power of a required DC power supply are connected in series, and the total DC voltage is collectively obtained by using a DC/DC converter to obtain the required DC voltage. be.

FIG. 10 is a diagram showing the configuration of a conventional storage battery system 101. As shown in FIG.

As shown in FIG. 10, a conventional storage battery system 101 has a plurality of units U-1 to U-k. The units U-1 to U-k respectively have battery packs 11-1 to 11-k and CMUs (Cell Monitoring Units) 12-1 to 12-k in which cell batteries are connected in series.

The assembled batteries 11-1 to 11-k of each unit U-1 to k are connected in series, and the output is connected to the DC/DC converter 21 via the switch S. Switch S is turned on when control of storage battery system 101 is started.

A current detector 13 is provided between the switch S and the DC/DC converter 21 . The current detector 13 detects the assembled battery current Ik flowing through the assembled batteries 11-1 to k of the plurality of units U-1 to k, and outputs it to the DCDC control section 52 as shown in FIG.

The DC/DC converter 21 consists of a coil 31, a transistor and a diode, a switch 32B controlled during discharge mode, and a switch 32A controlled during charge mode and connected to the output side. It has a capacitor 33 .

A system current detector 15 and a system voltage detector 16 are provided at the output of the DC/DC converter 21 and are controlled to match given reference values.

The CMUs 12-1 to 12-k collect assembled battery information such as the voltage and temperature of the assembled batteries 11-1 to 11-k, respectively, and send the collected assembled battery information to a battery system monitoring device (BMU: Battery Manager Unit) 14 . Send. The BMU 14 calculates the charge amount SOC based on the assembled battery information transmitted from the CMUs 12-1 to 12-k and the assembled battery current Ik flowing through the assembled batteries 11-1 to 11-k detected by the current detector 13. FIG.

The BMU 14 determines whether the assembled batteries 11-1 to k are within the operable range based on the calculated charge amount SOC, and determines that the assembled batteries 11-1 to k are within the operable range. If so, the state of charge SOC and the operation permission signal are output to the host controller 51 .

The host controller 51 outputs the DC voltage reference Vd ^* required by the system and the DC voltage Vd of the connection destination to the DCDC control unit 52 . The DCDC control unit 52 controls the switches 32A and 32B of the DC/DC converter 21 based on the DC voltage reference Vd ^* output from the host control device 51 and the DC voltage Vd of the connection destination.

FIG. 11 is a functional block diagram for explaining the operation of the DCDC control section 52. As shown in FIG.

When the DC voltage reference Vd ^* required for the storage battery system 101 and the DC voltage Vd of the connection destination are input from the host controller 51, the DCDC control unit 52 obtains the difference between them (Vd ^* -Vd).

The voltage control unit 61a obtains and outputs the DC current reference Id ^* from the difference (Vd ^* -Vd).

Depending on the system, the power may be specified by the host controller 301. In that case, the DC current reference Id ^* is calculated by dividing the specified power by a separately specified DC voltage. be. That is, the DCDC controller 52 is controlled by the DC current reference Id ^* , whether specified in voltage or power.

The mode determination unit 61b determines whether the mode is the power running mode or the regeneration mode based on the polarity of the DC current reference Id ^* output from the voltage control unit 61a. The calculation unit 61e is notified.

The conversion unit 61c converts the DC current reference Id ^* from the voltage control unit 61a into an assembled battery current reference |Ik ^* |. This conversion is
When Vd and Id are determined from the power balance of formula (1) (=Vk×Ik=Vd×Id), which will be described later, the assembled battery current reference |Ik ^* | converted. Here, the assembled battery current reference |Ik ^* | indicates the absolute value of the assembled battery current reference Ik ^* .

The difference ΔIk between the assembled battery current reference |Ik ^* |

That is, when ΔIk>0, the actual discharge or charge current is small, so the discharge or charge current is controlled to the command value by slightly increasing the DC voltage reference Vd ^* . In the case of the conventional example, since the assembled batteries 11-1 to 11-k are connected in series, they are controlled by the assembled battery current Ik.

Further, the battery current control section 61d performs control according to the mode (power running mode or regeneration mode) determined by the mode determination section 61b. That is, in the power mode, the assembled battery voltage Vk is boosted and the power is discharged to the DC voltage Vd side. In the regeneration mode, charging is performed by stepping down the DC voltage Vd to the assembled battery voltage Vk. Boost chopper control is performed in power mode (discharge mode), and step-down chopper control is performed in regenerative mode (charge mode).

A step-up ratio/duty ratio calculator 61e calculates a step-up ratio Vk/Vd, a duty ratio α _up (power mode), and α _down (regenerative mode) based on the assembled battery voltage Vk and the DC voltage Vd.

Here, ignoring the loss of the DC/DC converter 21,
Vk×Ik=Vd×Id (1)
is premised on the establishment of

The step-up ratio/duty ratio calculator 61e obtains the duty ratios α _up and α _down from the following equations (2) and (3).

Vk = (1- _αup ) x Vd (2)
Vk = α _down × Vd (3)
The voltage step-up ratio Vk/Vd calculated by the voltage step-up ratio/duty ratio calculation unit 61e, the duty ratio α _up (power mode), and α _down (regeneration mode) are input to the battery current control unit 61d. In the power mode (discharge mode), the gate circuit 61f is instructed to control the switch 32B according to the control target of the formula (2), and in the regeneration mode (charge mode), the switch 32A is controlled according to the control target of the formula (3). to the gate circuit 61f .

The gate circuit 61f controls the assembled battery current by outputting a gate signal to the switches 32A and 32B according to the mode based on the instruction from the battery current control section 61d.

A separate DC/DC converter is provided for each cell battery, and its output is further connected in series. A discharge control method for controlling discharge to obtain is proposed (Patent Document 1).

A discharge control method has also been proposed in which an H-bridge converter is connected to each assembled battery and the AC output thereof is further connected in series to adjust the output power during discharge in accordance with the SOC (state of charge) of the assembled battery. (Patent Document 2).

JP 2013-192388 A JP-A-11-98857

In the storage battery system 101 shown in FIGS. 10 and 11, the charge amount SOC of the battery packs 11-1 to 11-k is output from the BMU 14 to the host controller 51. FIG.

In a general storage battery system, discharging is continued until the SOC reaches the minimum SOC during discharging, and charging is continued until the SOC reaches the maximum SOC during charging.

When SOC variations occur between assembled battery modules, when the minimum SOC or maximum SOC is reached the earliest during discharging or charging, it is necessary to stop discharging or charging at that point.

However, when such control is performed, there is a problem that the operation time of the storage battery system is shortened. In addition, it is difficult to adjust the difference in the amount of charge SOC that occurs due to, for example, different usage conditions and characteristics for each assembled battery.

According to the embodiment, each includes an assembled battery in which a plurality of cell batteries are connected in series, an assembled battery voltage value of the assembled battery, an assembled battery current value of the current flowing through the assembled battery, and a charge amount of the assembled battery. A plurality of assembled battery modules connected in series, each having an acquisition unit for acquiring, a DC/DC converter for converting the assembled battery voltage of the assembled battery, and a control unit for controlling the DC/DC converter . a current detector for detecting current values of currents output from the plurality of assembled battery modules; a voltage detector for detecting voltage values on the output side of the plurality of assembled battery modules; and a plurality of assembled battery modules. a battery system monitoring device that monitors the DC current reference based on the required current, the assembled battery voltage values acquired by the acquisition units of the plurality of assembled battery modules, and the voltage Obtaining an average assembled battery current reference of the plurality of assembled battery modules using the voltage values detected by the detector, and obtaining the obtained average assembled battery current reference for the DC current reference and the plurality of assembled battery modules obtaining an assembled battery current reference for each of the plurality of assembled battery modules by correcting based on the charge amount acquired by the unit , notifying the obtained assembled battery current reference to the corresponding assembled battery module; Each of the control units of the plurality of assembled battery modules obtains an output voltage reference using the assembled battery current reference notified from the battery system monitoring device and the assembled battery current value, and converts the output voltage reference by the DC/DC converter. a storage battery system for controlling the DC/DC converter so that the voltage value of the voltage obtained becomes the output voltage reference obtained above .

It is a figure which shows the structure of the storage battery system 201 which concerns on this embodiment. 4 is a functional block diagram for explaining operations of a BMU 302 and a DCDC control unit 411 ; FIG. 4 is a flowchart for explaining the operation of the storage battery system 201 according to the embodiment; 4 is a flowchart for explaining the operation of the storage battery system 201 according to the embodiment; FIG. 4 is a diagram showing the temporal transition (during discharging) of the SOCs of the assembled batteries 11-1 to 11-k. FIG. 10 is a diagram showing the temporal transition (at the time of charging) of the SOCs of the assembled batteries 11-1 to 11-k; FIG. 11 is a functional block diagram for explaining operations of a BMU 302 and a DCDC control unit 411 according to another embodiment; It is a figure which shows a step-down chopper circuit. Fig. 2 shows a four-quadrant chopper circuit; It is a figure which shows the structure of the conventional storage battery system 101. FIG. 5 is a functional block diagram for explaining the operation of a DCDC control unit 52; FIG.

Embodiments will be described below with reference to the drawings. The same parts as those in FIG. 10 are given the same reference numerals for explanation.

FIG. 1 is a diagram showing the configuration of a storage battery system 201 according to this embodiment.

As shown in FIG. 1, the storage battery system 201 of the embodiment has a plurality of assembled battery modules 303-1 to 303-k connected in series.

The plurality of assembled battery modules 303-1 to 303-k include assembled batteries 11-1 to 11-k in which cell batteries are connected in series, CMUs (Cell Monitoring Units) 312-1 to 312-k, and DC/DC converters 401-1 to 401-k. have. CMUs 312 - 1 through k are connected to BMU 302 . The CMUs 312-1 to 312-k detect the assembled battery voltages V _{1 to k} of the assembled batteries 11-1 to k, the assembled battery currents I _{1 to k} detected by the current detectors 313-1 to 313-k, and the assembled batteries 11-1 to 11-k. Assembled battery information such as the temperature of k is collected, and the state of charge SOC is calculated based on the assembled battery information. Then, the collected battery pack information and charge amount SOC are transmitted to the battery system monitoring unit (BMU) 302 .

In assembled battery modules 303-1 to 303-k, assembled batteries 11-1 to 11-k are connected to DC/DC converters 401-1 to 401-k, respectively. Specifically, the switches S-1 through k of the DC/DC converters 401-1 through 401-k are connected to the respective outputs of the assembled batteries 11-1 through k. Outputs of the assembled batteries 11-1 to k are connected to one ends of coils 331-1 to k via switches S-1 to k.

Current detectors 313-1 to 313-k are provided between the switches S-1 to k and one ends of the coils 331-1 to 331-k, respectively. At the other ends of the coils 331-1-k, switches 332B-1-k consisting of transistors and diodes and controlled in the discharge mode, and switches 332A-k consisting of transistors and diodes and controlled in the charge mode. 1 to k are connected. Capacitors 333-1 to 333-k are respectively connected between the terminals of the switches 332A-1 to 332A-k and the switches 332B-1 to 332B-k and between the terminals to which the assembled battery module output voltages VM1 _{to k} are outputted. ing.
The DC/DC converters 401-1 to 401-k respectively convert the assembled battery voltages V1 to k of the assembled batteries 11-1 to k into the assembled battery module output voltages V _{M1 to k of} the assembled battery modules 303-1 to 303-k. Output.

A system current detector 15 and a system voltage detector 16 are provided at the outputs of the DC/DC converters 401-1 to 401-k. The system current detector 15 is connected to the BMU 302 and outputs to the BMU 302 the value of the assembled battery module output current Id common to each of the series-connected assembled battery modules 303-1 to 303-k. A DC voltage Vd detected by the system voltage detector 16 is input to the host controller 301 .

The DCDC controllers 411 - 1 to 411 -k are connected to the BMU 302 . The DCDC controllers 411-1-k are connected to the transistors of the corresponding switches 332A-1-k and switches 332B-1-k, respectively. DCDC controllers 411-1-k receive battery pack current references I ₁ ^* -I k ^* from BMU 302, respectively, and switch switches 332A-1- _k to satisfy the received battery pack current references I ₁ ^* -I _k ^* . 1 to k, 332B-1 to k.

That is, based on the assembled battery current references I ₁ ^* to I _k ^* received from the BMU 302, the DCDC control units 411-1 to 411-k adjust the assembled battery module output voltages V _{M1 to Mk} to the assembled battery output voltage reference V _Mk ^*. The switches 332A-1 to 332B-1 to 332B-k are controlled so that The assembled battery output voltage reference V _Mk ^* will be described later.
The host controller 301 outputs the DC voltage reference Vd ^* required by the system and the DC voltage Vd of the connection destination to the BMU 302 .

Based on the DC voltage reference Vd ^* output from the host controller 301, the DC voltage Vd of the connection destination, the assembled battery information and the charge amount SOC from the CMUs 312-1 to 312-k, the BMU 302 selects the assembled battery modules 303-1 to 303-k. k assembled battery current references I ₁ ^* to I _k ^* are output to the DCDC controllers 411-1 to 411-k, respectively.

FIG. 2 is a functional block diagram for explaining the operations of the BMU 302 and the DCDC control section 411. As shown in FIG. In the embodiment, in FIG. 2, the operations of the computing unit c1, the voltage control unit 101a to the current reference correction units 101e-1 to 101e-k are performed by the BMU 302, and the computing unit c2, the assembled battery current control unit 101f and the step-up ratio/current The operation of rate calculation unit 101g is performed by DCDC control units 411-1 to 411-k.

When the DC voltage reference Vd ^* required for the storage battery system 201 and the DC voltage Vd of the connection destination are inputted from the host control device 301, the BMU 302 obtains the difference between them (Vd ^* -Vd) by the calculator c1.

The voltage control unit 101a amplifies the difference (Vd ^* -Vd) between the DC voltage reference Vd ^* and the DC voltage Vd, and obtains the DC current reference Id from the current required for the entire system (current required on the system output side). ^* is obtained and output.

Depending on the system, the power from the storage battery system 201 may be specified. In that case, the DC current reference Id ^* is calculated by dividing the specified power by a separately specified DC voltage. be. That is, the BMU 302 is controlled by the DC current reference Id ^* , whether specified in either voltage or power.

The mode determination unit 101b determines whether the mode is the power running mode or the regeneration mode based on the polarity of the DC current reference Id ^* output from the voltage control unit 101a. Notify the rate calculation unit 101g.

Based on the result of the mode determination by the mode determination unit 101b, a difference in the control content of the step-down operation or step-up operation by the DCDC control units 411-1 to 411-k occurs.

That is, in the power mode, the assembled battery voltage _Vk is boosted and the power is discharged to the DC voltage Vd side. In the regeneration mode, charging is performed by stepping down the DC voltage Vd to the assembled battery voltage _Vk . Boost chopper control is performed in power mode (discharge mode), and step-down chopper control is performed in regenerative mode (charge mode). In this case, the calculation of the step-up ratio and duty ratio associated with the step-up/step-down operation is different as will be described later, but otherwise the control flow is the same in both modes.

During discharging, the average assembled battery current reference calculation unit 101c converts the DC voltage Vd detected by the system voltage detector 16 into the total voltage Vtotal (=V _{1 +V 2 +} . . . +V _k ) to calculate the average boost ratio. Next, the calculated average step-up ratio ^Vd /(V _{1 +} V _{2 +} ^. | is calculated. Here, the average assembled battery current reference | _Îk ^* | indicates the absolute value of the average assembled battery current reference _Îk ^* . Thus, the average assembled battery current reference |I^ _k ^* | can be set even when the assembled battery voltages V _{1 to k} of the respective assembled batteries 11-1 to k vary.

During charging, the average step-down ratio is calculated. The average step-down ratio is the reciprocal of the average step-up ratio, and the average step-down ratio=(V ₁ +V ₂ + . . . +V _k )/Vd.

again,
_I ^k ^** (V1 ₊ V2+...+Vk)=Vd*Id ^* ...(4)
is assumed to hold.

The individual assembled battery module current reference calculation unit 150 includes current reference correction amount calculation units 101d-1 to k and current reference correction units 101e-1 to k.

The current reference correction amount calculation units 101d-1 to 101d-k calculate the current correction amount ΔI _k of the average assembled battery current reference |I^ _k ^* | in order to eliminate the SOC imbalance of each of the assembled batteries 11-1 to k. do.

First, regarding the SOCs of the assembled batteries 11-1 to k, the SOC change amount ΔSOC _k that changes when the k-th assembled battery 11-k is discharged is SOC k (t0) for the current SOC at time t0, and SOC _k (t0) for the future When the SOC at time t1=t0+Δt is SOC _k (t1),
_ΔSOCk = _SOCk (t0) - _SOCk (t1)
= SOC _k (t0) - SOC _k (t0 + Δt) (5)
relationship is established.

First, for simplification, it is assumed that the assembled batteries 11-1 to 11-k and the DC/DC converters 401-1 to 401-k have no loss. The k-th assembled battery current is I _k (t), the assembled battery voltage is V k (SOC _k (t)), the assembled battery module output voltage is V _Mk (t), and the serially connected assembled battery modules 303-1 to Assuming that the output current of the assembled battery module common to k is the output current Id, the formula (6) holds.

_{Vk×Ik=VMk × Id} (6)
The SOC change ΔSOC _k is given by the integration of the current flowing through the assembled battery 11-k, and is given by the equation (7).

Here, QFC is the total amount of charge when the assembled battery 11-k is fully charged.

From the equation (6), the assembled battery current I _k (t) is given by the equation (8).

_{Ik = (VMk / Vk} ) x Id (8)
The output current Id(t) varies depending on the load, but when considering control, the target for eliminating the SOC imbalance cannot be set unless the load current is assumed. A constant current Id0 is assumed to calculate the short term target value.

The voltage conversion ratio of DC/DC converter 401-k is V _Mk /V _k , and even if the assembled battery voltage V _k (SOC _k (t)) varies depending on the SOC value, If the battery current I _k (t) is controlled to be constant, V _Mk /V _k is controlled to be constant from equation (8).

Therefore, if the assembled battery current I _k (t) is constant in equation (6),

becomes,
I _k =−ΔSOC _k ×QFC/Δt (9)
becomes.

Also, if the average value of ΔSOC _k is ΔSOC _k ^* and the average value of I _k is I^ _k ^* from the equation (9),
I ^ _k ^* = - ΔSOC _k ^* × QFC/Δt (10)
becomes.
However, ΔSOC _k <0 is discharge operation.

That is, if the SOC change amount ΔSOC _k and the time Δt to be applied to it are determined, and the assembled battery current I _k is supplied, the current satisfies the equation (9). Even if the SOC change ΔSOC _k ^* is the same, if the time Δt is shortened, the assembled battery current I _k will increase according to the equation (9). That is, the control is such that the assembled battery module output voltage V _Mk (t) is increased.

Using equation (10),
Current correction amount ΔI _k = (ΔSOC _k - ΔSOC ^* _k ) x (QFC/Δt)
is obtained.

Current reference correction amount calculation units 101d-1 to 101d-k calculate a set of DC current reference Id ^* output from voltage control unit 101a, control target Δt stored in BMU 302, SOC _k (t0+Δt), and CMU 312-1 to k. Set _assembled battery current | Output I _k |. Specifically, the assembled battery current _Ik is set based on equations (5) and (9).

The current reference correction units 101e-1 to 101e-k calculate the average assembled battery current reference from the average assembled battery current reference calculation unit 101c based on the assembled battery current |I _k | from the current reference correction amount calculation units 101d-1 to 101d-k. |I^ _k ^* | is corrected, and the corrected average assembled battery current reference |I^ _k ^* | of each of the assembled batteries 11-1 to k is output as the assembled battery current reference |I _k ^* |.

Each assembled battery output voltage reference unit 151 includes a computing unit c2, an assembled battery current control unit 101f, a step-up ratio/duty ratio calculation unit 101g, and a gate circuit 101h.

The step-up ratio/duty ratio calculator 101g obtains duty ratios α _up and α _down from the following equations (11) and (12).

V _k = (1−α _up )×V _Mk (11)
_Vk = _αdown × _VMk (12)
The assembled battery current control unit 101f stores the step-up ratio V _k /V _Mk for each individual assembled battery calculated by the step-up ratio/duty ratio calculation unit 101g, duty ratio α _up (power mode), α _down (regeneration mode ) is entered. In the power mode (discharge mode), the gate circuit 101h is instructed to control the switch 322B according to the control target of formula (11), and in the regeneration mode (charge mode), the switch 322A is controlled according to the control target of formula (12). The gate circuit 101h is instructed.

Also, the difference ΔI _k =|I _k ^* |−|I _k | between the assembled battery current reference |I _k ^* |−assembled battery current |I _k | be done. The assembled battery current control unit 101f controls the gate circuit 101h so that the input difference _ΔIk becomes zero.

Specifically, the assembled battery current control unit 101f controls the assembled battery module output voltages V _{M1 to MK} based on each assembled battery output voltage reference V _Mk ^* determined by the flowcharts of FIGS. The gate circuit 101h is controlled to be the voltage reference V _Mk ^* .

The gate circuit 101h controls the assembled battery current by outputting a gate signal to the switches 332A-k and 332B-k according to the mode based on the instruction from the assembled battery current control section 101f.

Next, the operation of the storage battery system 201 according to the embodiment will be described with reference to the flowcharts of FIGS. 3 and 4. FIG.

First, when the DC current reference Id ^* is obtained by the voltage control unit 101a of the BMU 302, the average voltage step-up ratio (=Vd/(V1 ₊ V2+...+ _Vk ) is calculated by the _average assembled battery current reference calculation unit 101c. is calculated (S1).

After that, from the relationship of the formula (4), the average assembled battery current reference calculation unit 101c calculates the DC current obtained by the voltage control unit 101a as the average step-up ratio (=Vd/(V ₁ +V ₂ + . . . +V _k ). The reference Id ^* is multiplied to set the average assembled battery current reference | _Îk ^* | (S2).

On the other hand, the current reference correction amount calculation unit 101d-1 sets the assembled battery current Ik according to the equations (5) and (9) in order to absorb the SOC imbalance of each of the assembled batteries 11-1 to 11- _k after Δt. (S3), and output to the current reference correction units 101e-1 to 101e-k.

Next, the current reference correction units 101e-1 to 101e-k calculate the assembled battery current |I _k | from the current reference correction amount calculation units 101d-1 to k and the average assembled battery current reference from the average assembled battery current reference calculation unit |I^ _k ^* | (S4), based on this difference, the average assembled battery current reference |I^ _k ^* | is corrected, and the assembled battery current reference | I _k ^* | is output (S5).

The difference ΔI _k =|I _k ^* |−|I _k | between the assembled battery current reference |I _k ^* |−the assembled battery current |I _k | is entered.

Next , based on the SOC _k (t0) of the own assembled batteries 11-1 to 11-k, the time Δt, and the target SOC _k (t1) at that time, the assembled battery current control unit 101f uses equations (5) and (9) V _Mk is calculated based on the equation (13) derived from (S7).

V _Mk = (−QFC×V _k /Id×Δt)×ΔSOC _k (13)
Next, the assembled battery current control unit 101f determines whether ΔSOC _k /ΔSOC(av)>1.1 (S8). Here, ΔSOC(av) is the average value of the SOC differences of the assembled batteries 11-1 to k.

If it is determined in S8 that ΔSOC _k /ΔSOC(av)>1.1 is not satisfied, V _Mk ^* =V _Mk is set.

If it is determined in S8 that ΔSOC _k /ΔSOC(av)>1.1,
_VMk ^* = _VMk +K'× _ΔSOCk /SOC(av)= _VMk +ΔV (14)
set as

That is, ΔSOC _k is obtained from SOC _k (t0) and SOC _k (t 1 ), and ΔSOC _k /SOC(av) is, for example, 1.1 times or more (10% or higher SOC) during discharge. For the assembled battery module 303-k, the coefficient K' (for example, 1.15 times, 1.2 times, etc., a large discharge current) is determined in consideration of the target time Δt from the equation (9), Correction amount.

In the case of discharge operation, when expressed as K′×ΔSOC _k /SOC(av)=ΔV in the equation (14),
If ΔI _k >0 (the actual discharge power is small), V _Mk ^*′ =V _Mk ^* +ΔV (that is, control to reduce ΔI _k ). Note that V _Mk ^*' is the corrected voltage reference in the next control routine.

If ΔI _k <0 (the actual discharge power is large), V _Mk ^*′ =V _Mk ^* −ΔV (that is, control to increase ΔI _k ).

_VMk ^*' = _VMk ^* +K'× _ΔSOCk /SOC(av)= _VMk +ΔV (14)
In other words, it is possible to converge to the target value by performing the correction using the formula (14).

In addition, in the case of charging operation, the same control is performed except for the calculation of the step-up ratio and duty ratio described above.
If ΔI _k >0 (the actual charging power is small), V _Mk ^*′ =V _Mk ^* +ΔV (that is, control to reduce ΔI _k ). Here, V _Mk ^*' is the corrected voltage reference.

If ΔI _k <0 (the actual charging power is large), V _Mk ^*′ =V _Mk ^* −ΔV (that is, control to increase ΔI _k ).

Assuming that V _Mk ^*' is the corrected voltage reference, similarly V _Mk ^*' = V _Mk ^* + K' × ΔSOC _k /SOC(av) = V _Mk ^* + ΔV (14)
In other words, it is possible to converge to the target value by performing the correction using the formula (14).

FIG. 5 is a diagram showing the temporal transition (at the time of discharging) of the SOCs of the assembled batteries 11-1 to 11-k. FIG. 6 is a diagram showing the temporal transition (at the time of charging) of the SOCs of the assembled batteries 11-1 to 11-k.

As shown in FIGS. 5 and 6, during both discharging and charging, the control for SOC balance elimination is performed from the current time (to) to the target time (t1). The SOCs of the batteries 11-1 to k are controlled to the SOC target SOC _k (t1). In this case, it is assumed that the discharge control or charge control mode continues until the target time (t1).

That is, as a result of the assembled battery current control, if the first assembled battery module output voltage V _M1 and the k-th assembled battery module output voltage V _Mk continue to operate at a constant current Id0 for the time Δt, both assembled batteries This indicates that the SOCs have the same value.

However, if the total DC voltage is determined to be within a certain range based on the configuration of the main circuit, and the total voltage of the calculation results _{V M1} , . Therefore, the variable Δt, SOCk(t1) or Id0 is set again, and _{V′M1 V′Mk} is adjusted so that the total DC voltage falls within a certain range. It suffices to determine the allotted voltage, and if the operation is continued with the constant current I'd0 at that voltage, the SOC becomes the same value after the time Δt' of the new control target.
<Other embodiments>
FIG. 7 is a functional block diagram for explaining operations of the BMU 302 and the DCDC controller 411 according to another embodiment. 2, the host control device 301 gives the command value of the DC power P ^* of the entire assembled batteries 11-1 to k and the power P of the entire assembled batteries 11-1 to k to the BMU 302. FIG.

The power P of the entire assembled batteries 11-1 to k is obtained by collecting the assembled battery voltages V _{1 to k} and the assembled battery currents I _{1 to k} from the assembled batteries 11-1 to k, is obtained by summing

After that, the difference (P ^* -P) between the power P ^* of the entire assembled battery 11-1 to k and the power P of the entire assembled battery 11-1 to k is obtained, and the difference (P ^* - P) is divided by the DC voltage Vd to convert the controlled object to a DC current reference Id ^* . Subsequent processing is the same as the processing of the embodiment shown in FIG.

The storage battery system 501 of another embodiment is effective in a system that performs power control using the power amount of all of the assembled batteries 11-1 to k as a control amount.
<Modification>
In the above-described embodiment, the step-up chopper circuit in which the voltage of the assembled battery < the DC voltage on the output side has been described as an example in accordance with the example of a general storage battery system. The step-down chopper circuit shown in FIG. 9 and the four-quadrant chopper circuit shown in FIG. 9 may be used.

In a conventional system in which assembled batteries with different SOCs are connected in series, output currents from the assembled batteries are the same, so other assembled batteries reach the lowest SOC before reaching the lowest SOC due to SOC imbalance. Therefore, the system as a whole has no choice but to stop discharging even though there is still a charge amount that can be discharged. According to the storage battery system of the embodiment, it is possible to solve such problems.

That is, current control is optimally performed during discharging or charging so as to eliminate the SOC imbalance (for example, during discharging operation, the target SOC at time t1 is adjusted to the minimum SOC (maximum SOC during charging). By doing so, it became possible to use up each assembled battery to the lowest SOC. Of course, this time t1 can be set arbitrarily within the range in which the current of the assembled battery can be controlled. It is also possible to eliminate all SOC imbalances at t1.

Further, in comparison with the conventional example, Patent Document 1 proposes to connect booster circuits to individual cells and to control the boosts by totaling them. However, there is no mention of controlling the voltage of the entire assembled battery.

Furthermore, as described in Patent Document 2, by installing means for controlling the output power of the power cell to which the battery is connected in accordance with the remaining power amount of the battery for each power cell, the remaining power amount of the battery can be adjusted. Averaging has also been attempted. However, even in this case, there is no mention of boosting the assembled battery voltage of the assembled battery.

In the embodiment, by installing a DC/DC converter for each assembled battery, it is possible to provide an individual voltage reference for the assembled battery from the DC voltage required for the entire system, thereby improving the overall storage battery system. When designing, there is no need to design a DC/DC converter each time as in the conventional art.

In addition, according to the embodiment, it is possible to build a storage battery system that can be handled only by changing the number of series of assembled batteries, and it is also possible to deal with a system that contributes to strengthening system responsiveness (no need to design each time). It has become possible.

In the above description, the operations of voltage control unit 101a to current reference correction unit 101e1 to k are performed by BMU 302, and the operations of assembled battery current control unit 101f and step-up ratio/duty ratio calculation unit 101g are performed by DCDC control unit 411. -1 to k have been described, but the arrangement of these functional blocks can be flexibly performed.

According to the storage battery system of the embodiment, it is possible to optimally set the output voltage of each assembled battery module connected in series so as to eliminate variations in SOC. A system can be provided that extends the operating time as a whole.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

15...System current detector 16...System voltage detector 150...Individual assembled battery module current reference calculation unit 151...Each assembled battery output voltage reference unit 201, 501...Storage battery system 301...Upper control device 302... BMU, 303-1 to k... Battery module, 312-1 to k... CMU, 313-1 to k... Current detector, 401-1 to k... DC/DC converter, 411-1 to k... DCDC control unit .

Claims (6)

each of which acquires an assembled battery in which a plurality of cell batteries are connected in series, an assembled battery voltage value of the assembled battery, an assembled battery current value of the current flowing through the assembled battery, and a charge amount of the assembled battery; a plurality of assembled battery modules connected in series, each including a DC/DC converter for converting an assembled battery voltage of the assembled battery and a control unit for controlling the DC/DC converter ;
a current detector that detects current values of currents output from the plurality of assembled battery modules;
a voltage detector that detects voltage values on the output sides of the plurality of assembled battery modules;
a battery system monitoring device that monitors the plurality of assembled battery modules,
The battery system monitoring device
Using a DC current reference based on the required current, the assembled battery voltage values acquired by the acquisition units of the plurality of assembled battery modules, and the voltage values detected by the voltage detectors , Obtaining the average battery current standard ,
By correcting the obtained average assembled battery current reference based on the DC current reference and the amount of charge acquired by the acquiring unit of the plurality of assembled battery modules, the assembled battery current of each of the plurality of assembled battery modules Seeking standards,
Notifying the corresponding assembled battery module of the obtained assembled battery current reference ,
Each of the control units of the plurality of assembled battery modules,
Obtaining an output voltage reference using the assembled battery current reference notified from the battery system monitoring device and the assembled battery current value,
controlling the DC/DC converter so that the voltage value of the voltage converted by the DC/DC converter becomes the determined output voltage reference;
battery system. When the assembled battery module is discharged, the battery system monitoring device divides the voltage value detected by the voltage detector by the total value of the assembled battery voltage values of the plurality of assembled battery modules, and multiplies the voltage value by the DC current reference. 2. The storage battery system of claim 1, wherein the average battery pack current reference is determined by: During charging of the assembled battery module, the battery system monitoring device divides the total value of the assembled battery voltage values of the plurality of assembled battery modules by the voltage value detected by the voltage detector, and multiplies the sum by the DC current reference. 2. The storage battery system of claim 1, wherein the average battery pack current reference is determined by: 2. The storage battery system of claim 1, wherein the DC current reference is determined using a required DC voltage reference and the voltage value detected by the voltage detector . The DC current reference is the sum of the power reference required as the power of the entire assembled battery of the plurality of assembled battery modules and the total power of the assembled battery of the plurality of assembled battery modules obtained by the battery system monitoring device. 2. The storage battery system of claim 1, wherein the storage battery system is determined using 2. The storage battery system according to claim 1, wherein said DC/DC converter is one of a step-up chopper circuit, a step-down chopper circuit, and a four-quadrant chopper circuit.

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