JPH01227636A - Operation control method for a plurality of batteries - Google Patents

Operation control method for a plurality of batteries

Info

Publication number
JPH01227636A
JPH01227636A JP5066688A JP5066688A JPH01227636A JP H01227636 A JPH01227636 A JP H01227636A JP 5066688 A JP5066688 A JP 5066688A JP 5066688 A JP5066688 A JP 5066688A JP H01227636 A JPH01227636 A JP H01227636A
Authority
JP
Japan
Prior art keywords
batteries
battery
charging
group
discharging
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP5066688A
Other languages
Japanese (ja)
Inventor
Takeshi Yamayoshi
武 山吉
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kyocera Corp
Original Assignee
Kyocera Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kyocera Corp filed Critical Kyocera Corp
Priority to JP5066688A priority Critical patent/JPH01227636A/en
Publication of JPH01227636A publication Critical patent/JPH01227636A/en
Pending legal-status Critical Current

Links

Landscapes

  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

PURPOSE:To lengthen a battery life, by dividing a plurality of batteries into two groups or more and by operating them through causing a discharge time and a charge time to deviate from each other. CONSTITUTION:On the first day, a diverter switch 4 is moved to the (a) side and a diverter switch 5, to the (b) side so that A group batteries 6 are charged with DC power from a solar battery 1 in the duration of sunshine while power is also supplied from B group batteries 7 to a DC load 8 or converted into AC by an inverter 13 and supplied to an AC load 14. On the second day, said diverter switch 4 is moved to the (b) side and said diverter switch 5, to the (a) side so that said B group batteries 7 are charged in the duration of sunshine while said A group batteries 6 are discharged. Said process is repeated on and after the third day.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は太陽光発電システムや風力発電システムのよう
に複数個のバッテリイーを具備し、発電された電力をバ
ッテリイーに充電し、負荷に供給する装置の複数個のバ
ッテリイーの運転制御方式%式% 〔従来技術及び発明が解決しようとする課題〕比較的大
きい容量の太陽光発電システム等では複数個のバッテリ
イーが備えられており、昼間に太陽電池で1日でまかな
える電力量をこの複数個のバッテリイー全部に同時に充
電し、夜間等に同時にこの複数個のバッテリイーから負
荷に電力を供給している。即ち、複数個のバッテリイー
全部を1日1サイクルで同時に充電し、同時に放電する
という運転制御方式である。しかしながらこのような従
来のバッテリイーの運転制御方式は下記のような欠点が
あった。
[Detailed Description of the Invention] [Industrial Application Field] The present invention includes a plurality of batteries e, such as a solar power generation system or a wind power generation system, and charges the generated electric power to the battery e and supplies it to a load. Operation control method for a plurality of batteries in a supply device % [Prior art and problems to be solved by the invention] A solar power generation system with a relatively large capacity is equipped with a plurality of batteries. During the day, all of these batteries are simultaneously charged with the amount of power that can be covered in one day by the solar cells, and at night, etc., power is simultaneously supplied to the load from these batteries. That is, this is an operation control method in which all the batteries are simultaneously charged and discharged in one cycle per day. However, such conventional battery e operation control methods have the following drawbacks.

■昼間にバッテリイー全部を充電し、1日で放電するた
め、結局1日でバッテリイー全部が1サイクルを終了す
るため、バッテリイー寿命がシステム寿命に比較し極端
に短くなる。
■Since all Batteries are charged during the day and discharged in one day, all Batteries complete one cycle in one day, so the lifespan of Batteries is extremely short compared to the system life.

■複数個のバッテリイー全部を同時に充電放電を行なう
ため、故障が発生した負荷を一時停止させ、メンテナン
スを行わなければならない。
■Since all of the multiple batteries are charged and discharged at the same time, it is necessary to temporarily stop the faulty load and perform maintenance.

■複数個のバッテリイー全部を同時に充電放電するため
、連続不日照数を想定してバッテリイー容量を決定した
場合、バッテリイー容量が大きくなる。
■Since all of the multiple Batteries are charged and discharged at the same time, if the Battery E capacity is determined assuming the number of consecutive days of sunshine, the Battery E capacity will be large.

本発明は上述の点に鑑みてなされたもので、複数個のバ
ッテリイーを2つ以上のグループに分割し、放電時間と
充電時間′を互いにずらして運転することにより、バッ
テリイー寿命がながく、故障の場合負荷を停止させるこ
とがなく、且つバッテリイー容量が比較的少なくて済む
複数個のバッテリイーの運転制御方式を提供することを
目的とする。
The present invention has been made in view of the above-mentioned points, and by dividing a plurality of Batteries into two or more groups and operating them while staggering the discharging time and the charging time, the life of the Batteries can be extended. It is an object of the present invention to provide an operation control method for a plurality of batteries that does not stop the load in the event of a failure and that requires a relatively small battery capacity.

〔課題を解決するための手段〕[Means to solve the problem]

上記課題を解艇するため本発明は、第1図に示す充放電
制御装置3及び複数個のバッテリイー6.7を具備し、
太陽電池1(又はディーゼル発電機11)で発電された
直流電力又は及び交流を整流した直流電力を充放電制御
装置3を介して複数個のバッテリイー6.7を充電し、
該充電した電力を直流負荷8(又は交流負荷14)に供
給する複数個のバッテリイーの運転制御システムにおい
て、複数個のバッテリイーをAグループのバッテリイー
6とBグループのバッテリイー7に2分割し、これらA
グループバッテリイー6とBグループバッテリイー7の
間で充電時間と放電時間を相互にずらして運転すること
を特徴とする。
In order to solve the above-mentioned problems, the present invention includes a charge/discharge control device 3 and a plurality of battery units 6 and 7 shown in FIG.
Charge a plurality of batteries 6.7 with the DC power generated by the solar cell 1 (or the diesel generator 11) or the DC power obtained by rectifying the AC via the charge/discharge control device 3,
In an operation control system for a plurality of batteries e that supplies the charged power to a DC load 8 (or an alternating current load 14), the plurality of batteries e are divided into two into an A group battery e 6 and a B group battery e 7. And these A
It is characterized in that the charging time and discharging time between the group battery e 6 and the B group battery e 7 are shifted from each other.

〔作用〕[Effect]

上記のように複数個のバッテリーをAグループ及びBグ
ループに分割し、充電時間と放電時間を相互にずらして
行なうので、バッテリーの充放電サイクルが少なくなり
、後述のようにバッテリイー寿命が伸びる。また、複数
個のバッテリー ”をAグループ及びBグループに分割
し、充電と放電を互いに異なる時間に行なうので、非常
時のメンテナンスの場合、どちらか一方で負荷への電力
供給を継続させることができるから、負荷を停止するこ
となく行なうことが可能となる。
Since a plurality of batteries are divided into groups A and B and the charging and discharging times are staggered as described above, the number of charging and discharging cycles of the batteries is reduced, and the battery life is extended as will be described later. In addition, multiple batteries are divided into groups A and B, and charging and discharging are performed at different times, so in the case of emergency maintenance, one of the batteries can continue to supply power to the load. This makes it possible to perform this without stopping the load.

〔実施例〕〔Example〕

以下、本発明の一実施例を図面に基づいて説明する。 Hereinafter, one embodiment of the present invention will be described based on the drawings.

第1図はバッテリイーの運転制御方式を適用する発電シ
ステムの構成を示す図である。同図において、1は太陽
電池、2は切換開閉器、3は充放電制御装置、4,5は
羊れぞれ切換開閉器、6゜7はそれぞれバッテリイー、
8は直流負荷である。また、11はディーゼル発電機、
12は!!i流器、13はインバータ、14は交流負荷
であ門。
FIG. 1 is a diagram showing the configuration of a power generation system to which the battery e operation control method is applied. In the figure, 1 is a solar cell, 2 is a switching switch, 3 is a charging/discharging control device, 4 and 5 are switching switches, 6 and 7 are battery e, respectively.
8 is a DC load. In addition, 11 is a diesel generator,
12 is! ! 13 is an inverter, and 14 is an AC load.

切換蘭閉器2はa側に倒すと太陽電池1に接続きれ、b
側に倒すとディーゼル発電機11及び整流器1′2側に
接続される。また、切換開閉器4はa側に倒すと充放電
制御装置3の充′電徊に接続され、も側に倒すと充放電
制御装置3の放電側に接続される。また、切換開閉器5
をa側に倒すと充放電制御装置3の充電側に接続され、
b側に倒すと充放電制御装置3の放電側に接続される。
Switching switch 2 can be connected to solar cell 1 by tilting it to side a, and b
When tilted to the side, it is connected to the diesel generator 11 and rectifier 1'2 side. Further, when the switching switch 4 is tilted to the a side, it is connected to the charging side of the charge/discharge control device 3, and when it is tilted to the right side, it is connected to the discharge side of the charge/discharge control device 3. In addition, the switching switch 5
When turned to the a side, it is connected to the charging side of the charge/discharge control device 3,
When tilted to the b side, it is connected to the discharge side of the charge/discharge control device 3.

バッテリイー6及びバッテリイー7はそれぞれ複数個の
バッテリイーからなるバッテリイーをAグループ及びB
グループに分割したものである。
Battery e 6 and battery e 7 each group battery e consisting of a plurality of batteries e into groups A and B.
It is divided into groups.

上記構成の発電システムにおいて、ディーゼル発電機1
1は不日照日数が長い等、太陽電池1による発電が不可
能な場合の予備の発電機である。
In the power generation system with the above configuration, the diesel generator 1
Reference numeral 1 is a backup power generator in case the solar cell 1 is unable to generate electricity due to a long number of days without sunshine.

上記構成の発電システムにおいて、Aグループのバッテ
リイー6とBグループのバッテリイー7の充放電は第2
図に示すように行なう。即ち、切換開閉器2をa側に倒
し、太陽電池1を接続すると共に、1日目は切換開閉器
4をa(Itに倒し、切換開閉°器5をb側に倒しで、
日照時間において太陽電池1からの直流電力をAグルー
プのバッテリイー6を充電すると共にBグループのバッ
テリイー7から直流負荷8に供□給したり、インバータ
13で交流に変換し、交流負荷14に供給する。2日目
は切換開閉器4をb側に倒し、切換開閉器5をa側に倒
し′で、日照時間においてBグループのバッテリイー7
を充電すると共にAグループのバッテリイー6で放電を
行なう。3日目は切換開閉器4をa側に倒し、切換開閉
器5をb側に倒して、日照時間においてAグループのバ
ッテリイー6を充電すると共にBグループのバッテリイ
ー7で放電を行なう。このようにAグループのバッテリ
イー6とBグループのバッテリイー7の充放電を相互に
1日の時間をずらしてそれぞれ2日で1サイクル充放電
を行なうように運転する。上記のようにAグループのバ
ッテリイー6とBグループのバッテリイー7を充放電を
日をずらし行なうことにより、バッテリイー6及びバッ
テリイー7はそれぞれ2日で1サイクルの充放電を行な
うことになり、下記のようにバッテリイー寿命が長くな
る。
In the power generation system with the above configuration, charging and discharging of the A group battery e 6 and the B group battery e 7 is performed at the second stage.
Proceed as shown. That is, the switching switch 2 is turned to the a side and the solar cell 1 is connected, and on the first day, the switching switch 4 is turned to the a (It) position, and the switching switch 5 is turned to the b side.
During sunshine hours, the DC power from the solar cell 1 is used to charge the battery e 6 of the A group, and at the same time is supplied from the battery e 7 of the B group to the DC load 8, or is converted into AC power by the inverter 13, and then supplied to the AC load 14. supply On the second day, the switching switch 4 is moved to the b side, and the switching switch 5 is moved to the a side.
At the same time, the battery E6 of the A group is discharged. On the third day, the switching switch 4 is turned to the a side, and the switching switch 5 is turned to the b side, so that the battery e 6 of the A group is charged and the battery e 7 of the B group is discharged during sunshine hours. In this way, the charging and discharging of the battery e 6 of the A group and the battery e 7 of the B group are performed at different times of the day, such that one cycle of charging and discharging is performed every two days. By charging and discharging Battery E 6 in Group A and Battery E 7 in Group B on different days as described above, Battery E 6 and Battery E 7 will each perform one cycle of charging and discharging every two days. , the battery life will be longer as shown below.

第3図は蓄電池の放電深度とサイクル寿命の関係を示す
図である。図において、Gは1個のバッテリイーを用い
1日1サイクルの充放電を行なう場合のバッテリイー寿
命(年)を示し、Nは2個のバッテリイーを用い相互に
1日ずらしてそれぞれ2日で1ザイクル充放電する場合
を示す。図示するように、同し放電深度で1個のバッテ
リイーを1日1サイクで充放電を行なう場合に比較し、
2個のバッテリイー交互に日をずらしてそれぞれ2日で
1ザイクルの充電放電する場合はバッテリイー寿命が2
倍となる。
FIG. 3 is a diagram showing the relationship between the depth of discharge and cycle life of a storage battery. In the figure, G indicates the battery e lifespan (years) when one battery e is used and one cycle of charging and discharging is performed per day, and N is the battery e lifespan (years) when two batteries e are used and are shifted by one day from each other. This shows the case of one cycle of charging and discharging. As shown in the figure, compared to charging and discharging one battery at the same depth of discharge in one cycle per day,
If two batteries are charged and discharged for 1 cycle in 2 days on alternate days, the battery life will be 2.
It will be doubled.

第3図かられかるように、複数のバッテリイーを2グル
ープに分割し、交互に日をずらしてそれぞれ2日で1サ
イクルの充放電する場合は、この複数のバッテリイーを
全部同時に1日1サイクル充放電する場合に比較しバッ
テリイー寿命が2倍となる。また、例えは等しい容量の
10個のバッテリイーを放電深度20%で全部1日1サ
イクで充放電する場合のバッテリイー寿命は10.4年
であるのに対して、この10個のバッテリイーを5個づ
つ2つのグループに分割し、放電深度40%で交互に日
をすらしてそれぞれ2日で1ザイクル充電放電する場合
のそのバッテリイー寿命が14.2年となり、/スッテ
リイー容量が同じでもバッテリイー寿命3.8年長くな
ることが確認できる。このことはある容量のバッテリイ
ーを1個1日1サイクルで充放電する場合と、その1/
2の容量の2個のバッテリイーを交互に日をずらして2
日で1サイクル充電放電する場合とでもいえることであ
る。
As shown in Figure 3, if multiple batteries are divided into two groups and charged/discharged for one cycle every two days on alternating days, all of these batteries can be charged and discharged at the same time once a day. The battery life is doubled compared to the case of cyclic charging and discharging. For example, if 10 batteries with the same capacity are charged and discharged in one cycle per day at a depth of discharge of 20%, the battery life is 10.4 years. If the batteries are divided into two groups of 5 batteries each and charged and discharged for 1 cycle in 2 days each at a depth of discharge of 40%, the battery life will be 14.2 years, and the battery capacity will be the same. However, we can confirm that the battery life will be 3.8 years longer. This is true when one battery of a certain capacity is charged and discharged in one cycle per day, and when
Two batteries with a capacity of 2 are used alternately on different days.
This can be said to be equivalent to one cycle of charging and discharging per day.

なお、上記実施例では複数個のバッテリイーを2グルー
プに分割して運転する場合を示したが、分割するグルー
プ数は2グループに限定されるものではなく、それ以上
の複数グループでもよいことは当然である。また、グル
ープを構成するバッテリイー数は1個以上であればよい
In addition, in the above embodiment, a case where a plurality of battery units are divided into two groups and operated is shown, but the number of divided groups is not limited to two groups, and it is possible to use a larger number of groups. Of course. Further, the number of batteries constituting a group may be one or more.

また、上記実施例では、複数グループに分割したバッテ
リイーをそれぞれのグループ毎交互に1日ずらして2日
で1サイクル充電放電する場合の例を示したが、グルー
プ毎にずらす時間は1日に限定されるものではなく、1
日以上複数日でもよまく、また場合によっては1日以下
の時間でもよい。
In addition, in the above embodiment, an example was shown in which a battery e divided into multiple groups is charged and discharged for one cycle in two days by alternating each group by one day. without limitation, 1
It may be more than one day or more than one day, and in some cases it may be less than one day.

なお、上記実施例では太陽電池を具備する太陽光発電装
置を例に説明したが、発電装置は太陽光発電装置に限定
されるものではなく、複数個の蓄電池を具備するもので
あれば、例えば風力発電又は潮力発電等の発電装置でも
よいことは当然である。
In the above embodiment, a solar power generation device equipped with a solar cell was explained as an example, but the power generation device is not limited to a solar power generation device, and any power generation device equipped with a plurality of storage batteries can be used, for example. Naturally, a power generation device such as wind power generation or tidal power generation may also be used.

〔発明の効果〕〔Effect of the invention〕

以上説明したように本発明によれば、下記のような優れ
た効果が得られる。
As explained above, according to the present invention, the following excellent effects can be obtained.

■複数個のバッテリイーを2つ以上のグループに分割し
、充電時間と放電時間を相互にずらして行なうので、各
グループのバッテリーの充放電サイクルが少なくなり、
バッテリイー寿命が伸びる。
■Since multiple batteries are divided into two or more groups and the charging and discharging times are staggered, the number of charging and discharging cycles for each group of batteries is reduced.
Battery life is extended.

■また、複数個のバッテリーを2以上のグループに分割
し、充電と放電を互いに時間をずらして行なうので、非
常時のメンテナンスの場合、どちらか一方で負荷への電
力供給を継続させることができるから、負荷を停止する
ことなく行なうことが可能となる。
■Also, since multiple batteries are divided into two or more groups and charging and discharging are performed at staggered times, in the case of emergency maintenance, one of the batteries can continue to supply power to the load. This makes it possible to perform this without stopping the load.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図はバッテリイーの運転制御方式を適用する発電シ
ステムの構成を示す図、第2図はAグループのバッテリ
イーとBグループのバッテリイーを充放電状態を示す図
、第3図は蓄電池の放電深度とサイクル寿命の関係を示
す図である。 図中、1・・・・太陽電池、2・ ・切換開閉器、3・
・充放電制御装置、4・・・切換開閉器、5 ・・切換
開閉器、6  ・Aグループのバッテリ(−17・・・
・Aグループのバッテリイー、8・・・・直流負荷、1
1・・・・ディーゼル発電機、12・・・・整流器、1
3・・・・インバータ、14・・・・交流負荷。
Figure 1 is a diagram showing the configuration of a power generation system to which the Battery-E operation control method is applied, Figure 2 is a diagram showing the charging and discharging states of Battery-E in Group A and Battery-E in Group B, and Figure 3 is a diagram showing the charging and discharging states of Battery-E in Group A and Battery-E in Group B. FIG. 3 is a diagram showing the relationship between depth of discharge and cycle life. In the figure, 1... solar cell, 2... switching switch, 3...
・Charging/discharging control device, 4...Switching switch, 5...Switching switch, 6 -A group battery (-17...
・A group battery e, 8...DC load, 1
1... Diesel generator, 12... Rectifier, 1
3...Inverter, 14...AC load.

Claims (1)

【特許請求の範囲】[Claims] 充放電制御装置及び複数個のバッテリィーを具備し、発
電装置で発電された直流電力又は及び交流を整流した直
流電力を前記充放電制御装置を介して前記複数個のバッ
テリィーに充電し、該充電した電力を負荷に供給する複
数個のバッテリィーの運転制御システムにおいて、前記
複数個のバッテリィーを少なくとも2以上のグループに
分割し、これらグループに分割したバッテリィーの充電
時間と放電時間をグループ毎に相互にずらして運転する
ことを特徴とする複数個のバッテリィーの運転制御方式
A charging/discharging control device and a plurality of batteries are provided, and the plurality of batteries are charged with DC power generated by a power generation device or DC power obtained by rectifying alternating current through the charging/discharging control device. In an operation control system for a plurality of batteries that supplies power to a load, the plurality of batteries are divided into at least two or more groups, and the charging time and discharging time of the divided batteries are mutually shifted for each group. A system for controlling the operation of multiple batteries, which is characterized in that the batteries are operated in a controlled manner.
JP5066688A 1988-03-03 1988-03-03 Operation control method for a plurality of batteries Pending JPH01227636A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP5066688A JPH01227636A (en) 1988-03-03 1988-03-03 Operation control method for a plurality of batteries

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP5066688A JPH01227636A (en) 1988-03-03 1988-03-03 Operation control method for a plurality of batteries

Publications (1)

Publication Number Publication Date
JPH01227636A true JPH01227636A (en) 1989-09-11

Family

ID=12865276

Family Applications (1)

Application Number Title Priority Date Filing Date
JP5066688A Pending JPH01227636A (en) 1988-03-03 1988-03-03 Operation control method for a plurality of batteries

Country Status (1)

Country Link
JP (1) JPH01227636A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006287998A (en) * 2005-03-31 2006-10-19 Meidensha Corp Control unit for power storage device and method for controlling operation thereof
JP2010057267A (en) * 2008-08-28 2010-03-11 Nippon Telegr & Teleph Corp <Ntt> Direct-current power supply system and charging method therefor
WO2013046509A1 (en) * 2011-09-30 2013-04-04 パナソニック株式会社 Power supply system and power supply method
JP2015505237A (en) * 2012-01-12 2015-02-16 ジュ、ジングァンJU, Jingwan Power supply device using secondary battery and battery mode switching method of said power supply device

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006287998A (en) * 2005-03-31 2006-10-19 Meidensha Corp Control unit for power storage device and method for controlling operation thereof
JP4609156B2 (en) * 2005-03-31 2011-01-12 株式会社明電舎 Power storage device control device
JP2010057267A (en) * 2008-08-28 2010-03-11 Nippon Telegr & Teleph Corp <Ntt> Direct-current power supply system and charging method therefor
WO2013046509A1 (en) * 2011-09-30 2013-04-04 パナソニック株式会社 Power supply system and power supply method
JPWO2013046509A1 (en) * 2011-09-30 2015-03-26 パナソニックIpマネジメント株式会社 Power feeding system and power feeding method
JP2015505237A (en) * 2012-01-12 2015-02-16 ジュ、ジングァンJU, Jingwan Power supply device using secondary battery and battery mode switching method of said power supply device
JP2016192895A (en) * 2012-01-12 2016-11-10 ジュ、ジングァンJU, Jingwan Power supply device using secondary battery and battery mode conversion method for the same

Similar Documents

Publication Publication Date Title
US3909685A (en) Electrical apparatus
JP3147257B2 (en) Grid-connected power system
CN106816884A (en) Energy storage system
JPH0419673B2 (en)
CN104505867A (en) Alternating current and direct current hybrid micro-grid system and control strategy thereof
ITVA20010041A1 (en) SYSTEM OF ACCUMULATION AND / OR TRANSFORMATION OF ENERGY FROM SOURCES TO VOLTAGE AND FREQUENCY CHANGING
JP2002218654A (en) Photovoltaic power generation system
CN108493968B (en) Flywheel energy storage array and energy balance control method thereof
JPH01227636A (en) Operation control method for a plurality of batteries
JPS6450723A (en) Solar power generator
JP2001145396A (en) Composite power generation system
JPH0537637Y2 (en)
JPH0946912A (en) Distributed power unit
JP3201595U (en) Power supply
JP2000092741A (en) Control of electric power storing system
JPH01318519A (en) Method of supplying power for controlling solar photovoltaic power generation system
CN219513801U (en) Light storage integrated device
JP2003299256A (en) Method and apparatus for controlling charging/ discharging of secondary battery
WO2016129825A1 (en) Energy storage system using lead-acid battery, and charging/discharging method of lead-acid battery
JP2844748B2 (en) Solar power system
JPS635404Y2 (en)
JPS63231880A (en) Charge control method for lead-acid battery
JPS63217930A (en) Fuel cell generator
KR20190084909A (en) Apparatus for providing power in typed semiconductor hybrid to certain
Uplaonkar et al. Battery Balancing For a Multilevel Inverter