JP3945194B2

JP3945194B2 - Charger

Info

Publication number: JP3945194B2
Application number: JP2001212972A
Authority: JP
Inventors: 卓央荒舘; 信宏高野
Original assignee: Hitachi Koki Co Ltd
Current assignee: Koki Holdings Co Ltd
Priority date: 2001-07-13
Filing date: 2001-07-13
Publication date: 2007-07-18
Anticipated expiration: 2021-07-13
Also published as: JP2003032911A

Description

【０００１】
【発明が属する技術分野】
本発明はニッケル・カドミウム電池（以下ニカド電池という）やニッケル・水素電池（以下ニッケル水素電池という）等の２次電池を充電する充電装置に関するものである。
【０００２】
【従来の技術】
電動工具等の電源に用いられているニッケルカドミニウム電池やニッケル水素電池等を充電する方法の１つとして、特開平１１−３５５９７１号に開示の如く、充電時の電池温度及び温度上昇値が高い（低い）時は小さい（大きい）充電電流で充電できるようにし、電池温度の上昇を抑え且つ急速に充電し得る充電電流の許容値を、電池温度値と、電池の温度上昇値に基づきマッピングしたマップを、例えば周囲温度と電池温度の差の温度差に対応して複数記憶し、検出及び演算した電池温度及び電池温度上昇値に基き選択したマップ内から一定周期毎に充電電流許容値を検索し、この検索した充電電流により充電すると共に前記電池温度と電池温度上昇値とがマップ中における温度上昇値が大きい領域及び電池温度が高く温度上昇値が中程度の領域である充電末期領域に属する頻度が高いか否かに基づき満充電を判断する充電装置が提案されている。
【０００３】
【発明が解決しようとする課題】
しかしながら、かかる充電装置においては、周囲温度が電池温度に対して高い場合、充電開始直後から電池温度と周囲温度との温度勾配によって温度上昇値が高くなり、このような現象を想定していないマップにおいては充電末期を示す領域において頻繁に充電を行ってしまい、ほとんど充電されることなく満充電と判断されて、充電不足を生じる。
また周囲温度を検出するためには電池温度を検出するセンサ以外のセンサが新たに必要となり、構成が複雑になるという問題がある。
【０００４】
本発明の目的は、上記した従来技術の欠点をなくし、周囲温度が電池温度に対して相対的に所定値以上高い場合においても、充電早切れによる充電不足を起こすことなく充電できるようにすると共に満充電を確実に判別できるようにすることである。
【０００５】
【課題を解決するための手段】
上記目的は、冷却ファンを充電前に所定時間作動させて冷却前後の電池温度の差を求め、この差に対応して前記マップを選択し、選択したマップ内の充電電流の許容値を検索し検索した許容値により充電することにより達成される。
【０００６】
【発明の実施の形態】
図１は本発明の一実施形態を示す回路図である。１は交流電源、２は複数の素電池を直列接続した電池組であって、素電池に接触または近接して電池温度を検出する例えばサーミスタ等からなる電池温度検出手段装備されている。３は電池組２に流れる充電電流を検出する電流検出手段、４は充電の開始及び停止を制御する信号を伝達する充電制御信号伝達手段、５は充電電流の信号をＰＷＭ制御ＩＣ２３に帰還する充電電流信号伝達手段である。充電制御伝達信号手段４及び充電電流信号伝達手段５はホトカプラ等からなる。６は電池組２を冷却する冷却ファン、７は冷却ファン６を駆動する駆動手段であり、トランジスタ７ａ、抵抗７ｂ、７ｃから構成され、マイコン５０の出力ポート５６ｂの出力に応じて冷却ファン６の駆動を制御する。１０は全波整流回路１１と平滑用コンデンサ１２からなる整流平滑回路、２０は高周波トランス２１、ＭＯＳＦＥＴ２２とＰＷＭ制御ＩＣ２３からなるスイッチング回路である。ＰＷＭ制御ＩＣ２３はＭＯＳＦＥＴ２２の駆動パルス幅を変えて整流平滑回路２０の出力電圧を調整するスイッチング電源ＩＣである。３０はダイオード３１、３２、チョークコイル３３、平滑用コンデンサ３４からなる整流平滑回路、４０は抵抗４１、４２からなる電池電圧検出手段で、電池組２の端子電圧を分圧する。５０は演算手段（ＣＰＵ）５１、ＲＯＭ５２、ＲＡＭ５３、タイマ５４、Ａ／Ｄコンバータ５５、出力ポート５６ａ、５６ｂ、リセット入力ポート５７からなるマイコンである。６０は演算増幅器６１、６２、抵抗６３〜６６からなる充電電流制御手段、７０は電源トランス７１、全波整流回路７２、３端子レギュレータ７３、７４、平滑コンデンサ７５〜７７、リセットＩＣ７８からなる定電圧電源で、冷却ファン６、マイコン５０、充電電流制御手段６０等の電源となる。リセットＩＣ７８はマイコン５０を初期状態にするためにリセット入力ポート５７にリセット信号を出力する。８０は充電電流を設定する充電電流設定手段であって、前記出力ポート５６aからの信号に対応して演算増幅器６２の反転入力端に印加する電圧値を変えるものである。
【０００７】
図２は周囲温度と電池温度との差が小さい時に選択されるマップの一例で、電池温度Ｔ及び電池温度上昇値ΔＴに応じて検索される充電電流の許容値Ｉ１１〜Ｉ６６を示し、また斜線部は充電末期に検索される領域を示す。すなわち電池温度上昇値ΔＴが大きい領域（Ｉ５１〜Ｉ６６）や電池温度Ｔが高く電池温度上昇値ΔＴが中程度の領域（Ｉ４５、Ｉ４６）が充電末期に検索される領域である。
【０００８】
図３は周囲温度と電池温度との差が大きい時に選択されるマップの一例で、電池温度上昇値ΔＴが大きくなる傾向があるので、マップ左下側の領域（すなわちＩ４１、Ｉ４２、Ｉ５１、Ｉ５２、Ｉ６１、Ｉ６２）の縦幅を狭めこの領域の分解能を上げている。斜線部は図２同様充電末期に検索される領域を示す。
【０００９】
次に図１の回路図、図２、図３及び図４のフローチャートを参照して本発明充電装置の動作を説明する。
【００１０】
電源を投入するとマイコン５０は出力ポート５６a、５６ｂをイニシャルセットし、電池組２の接続待機状態となる（ステップ１０１）。電池組２が接続されると、冷却ファン６が作動する前の電池温度Ｔ₁を電池温度検出手段２Ａの出力からＡ/Ｄコンバータ５５を介して検出し（ステップ１０２）、その後冷却ファン６を作動させ（ステップ１０３）、タイマスタートする（ステップ１０４）。冷却ファン６作動後、所定時間が経過した否かをチェックし（ステップ１０５）、所定時間が経過した場合は、その時点での電池温度Ｔ₂を電池温度検出手段２Ａの出力からＡ/Ｄコンバータ５５を介して検出し（ステップ１０６）、所定時間が経過した時点での電池温度Ｔ₂と、冷却ファン６が作動する前の電池温度Ｔ₁とを比較演算し（ステップ１０７）、その演算値が判別値より小さい時は、周囲温度と電池温度との差が小さいと判断して、マイコン５０は図２のマップを選択し（ステップ１０８）、前記比較演算値が判別値より大きい時は、周囲温度と電池温度との差が大きいと判断、マイコン５０は、図３の第２のマップを選択し（ステップ１０９）、周囲温度が電池温度に対して相対的に高い場合において、充電初期に電池の温度が急激に上昇することにより満充電であると判断することに起因する早切れを起こすことなく、充電を行うことができる。
【００１１】
マップ選択後充電を開始し（ステップ１１０）、充電中の電池温度Ｔを所定周期毎に電池温度検出手段２Ａの出力から検出すると共に（ステップ１１１）、温度上昇値ΔＴを求め（ステップ１１２）、この電池温度値Ｔ及び温度上昇値ΔＴに基づきマイコン５０はマップを検索して温度上昇を抑えながら充電し得る充電電流の許容電流値を求める。
【００１２】
次にマイコン５０は、検索した許容値が図２または図３の選択したマップ中で斜線部で示す充電末期領域に入ったか否かを判断する（ステップ１１４）。充電末期領域に入らない時はステップ１１５に進みステップ１１３で求めた許容値での充電を継続し、ステップ１１１に戻る。充電末期領域に入った時は、充電末期領域に入る確率が高いか否かを判断する（ステップ１１６）。例えば、３周期連続して、充電末期領域に入った場合は、充電末期領域に入る確率が高いと判断する。充電末期領域に入っても、３周期連続充電末期領域に入らなかった場合は、充電末期領域に入る確率が高いと判断されず、ステップ１１５を介してステップ１１１に戻る。３周期連続充電末期領域に入った場合は、充電末期領域に入る確率が高いと判断され、充電を完了する（ステップ１１７）。
【００１３】
以上のように上記実施形態においては、充電を開始する前に冷却ファン６を所定時間作動させ、周囲温度に対応する温度の風を電池組２に当てるので、前記電池温度Ｔ₂は周囲温度に近くなり周囲温度に対応する温度となる。従って電池組２内の電池温度検出手段２Ａのみで電池温度及び周囲温度を検出できるようになり、周囲温度検出用の新たな温度検出手段を追加する必要がなくなり、構成が簡単になる。
【００１４】
上記実施形態のステップ１０９において周囲温度が電池温度より高いと判断した時に図３のマップを選択するとしたがこれに限るものではなく、例えば図５に示すようなマップ中で斜線部で示す温度上昇値ΔＴが大きい領域及び電池温度Ｔが高く温度上昇値ΔＴが中程度の領域である充電末期領域を狭めたマップでも構わない。
【００１５】
【発明の効果】
以上のように本発明によれば、周囲温度が電池温度に対して高い場合、充電開始直後から電池温度と周囲温度との温度勾配によって温度上昇値が高くなり、その結果これを起因とする充電早切れによる充電不足をなくし、確実な満充電判別が可能となる。
【図面の簡単な説明】
【図１】本発明充電装置の一実施形態を示す回路図。
【図２】周囲温度と電池温度との差が小さい時に選択されるマップの一例の内容を示す説明図。
【図３】周囲温度と電池温度との差が大きい時に選択されるマップの一例の内容を示す説明図。
【図４】本発明充電装置の動作説明用フローチャート。
【図５】周囲温度と電池温度との差が大きい時に選択されるマップの他の例の内容を示す説明図。
【符号の説明】
２は電池組、２Ａは電池温度検出手段、６は冷却ファン、５０はマイコンである。[0001]
[Technical field to which the invention belongs]
The present invention relates to a charging device for charging a secondary battery such as a nickel-cadmium battery (hereinafter referred to as a nickel-cadmium battery) or a nickel-hydrogen battery (hereinafter referred to as a nickel-hydrogen battery).
[0002]
[Prior art]
As one of methods for charging a nickel cadmium battery, a nickel hydride battery, or the like used for a power source of an electric power tool or the like, as disclosed in JP-A-11-355971, a battery temperature and a temperature increase value during charging are high ( When the battery is low (low), it is possible to charge with a small (large) charging current, and a map that maps the allowable value of the charging current that can suppress the battery temperature rise and can be rapidly charged based on the battery temperature value and the battery temperature rise value. Are stored in correspondence with the temperature difference between the ambient temperature and the battery temperature, for example, and the charging current allowable value is searched for every fixed period from the map selected based on the detected and calculated battery temperature and the battery temperature increase value. The battery temperature and the battery temperature increase value are charged by the searched charging current, and the region where the temperature increase value is large in the map and the battery temperature is high and the temperature increase value is intermediate. Charging apparatus has been proposed which frequency belonging to the charging end region which is a region to determine the full charge based on whether high or not.
[0003]
[Problems to be solved by the invention]
However, in such a charging device, when the ambient temperature is higher than the battery temperature, the temperature rise value increases due to the temperature gradient between the battery temperature and the ambient temperature immediately after the start of charging, and the map does not assume such a phenomenon. , Charging is frequently performed in a region indicating the end of charging, and it is determined that the battery is fully charged with almost no charging, resulting in insufficient charging.
Further, in order to detect the ambient temperature, a sensor other than the sensor for detecting the battery temperature is newly required, and there is a problem that the configuration becomes complicated.
[0004]
The object of the present invention is to eliminate the drawbacks of the prior art described above, and to enable charging without causing shortage of charging due to premature charging even when the ambient temperature is higher than a predetermined value relative to the battery temperature. This is to ensure that full charge can be determined.
[0005]
[Means for Solving the Problems]
The purpose is to operate the cooling fan for a predetermined time before charging to determine the difference in battery temperature before and after cooling, select the map corresponding to this difference, and search the allowable value of charging current in the selected map. This is accomplished by charging with the retrieved tolerance.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a circuit diagram showing an embodiment of the present invention. Reference numeral 1 denotes an AC power source. Reference numeral 2 denotes a battery set in which a plurality of unit cells are connected in series, and is equipped with a battery temperature detection means including, for example, a thermistor that detects a battery temperature in contact with or close to the unit cells. 3 is a current detecting means for detecting a charging current flowing in the battery set 2, 4 is a charging control signal transmitting means for transmitting a signal for controlling the start and stop of charging, and 5 is a charging for returning a charging current signal to the PWM control IC 23. Current signal transmission means. The charging control transmission signal means 4 and the charging current signal transmission means 5 are made of a photocoupler or the like. Reference numeral 6 denotes a cooling fan that cools the battery set 2, and 7 denotes a driving unit that drives the cooling fan 6. The driving unit includes a transistor 7 a and resistors 7 b and 7 c, and the cooling fan 6 is controlled according to the output of the output port 56 b of the microcomputer 50. Control the drive. Reference numeral 10 denotes a rectifying / smoothing circuit comprising a full-wave rectifying circuit 11 and a smoothing capacitor 12, and 20 is a switching circuit comprising a high-frequency transformer 21, a MOSFET 22 and a PWM control IC 23. The PWM control IC 23 is a switching power supply IC that adjusts the output voltage of the rectifying and smoothing circuit 20 by changing the drive pulse width of the MOSFET 22. A rectifying / smoothing circuit 30 includes diodes 31 and 32, a choke coil 33, and a smoothing capacitor 34. A battery voltage detecting unit 40 includes resistors 41 and 42, and divides the terminal voltage of the battery set 2. Reference numeral 50 denotes a microcomputer comprising a calculation means (CPU) 51, a ROM 52, a RAM 53, a timer 54, an A / D converter 55, output ports 56a and 56b, and a reset input port 57. 60 is a charging current control means comprising operational amplifiers 61 and 62 and resistors 63 to 66, 70 is a constant voltage comprising a power transformer 71, a full-wave rectifier circuit 72, three-terminal regulators 73 and 74, smoothing capacitors 75 to 77, and a reset IC 78. The power source is a power source for the cooling fan 6, the microcomputer 50, the charging current control means 60, and the like. The reset IC 78 outputs a reset signal to the reset input port 57 in order to bring the microcomputer 50 into an initial state. Reference numeral 80 denotes charging current setting means for setting a charging current, which changes a voltage value applied to the inverting input terminal of the operational amplifier 62 in response to a signal from the output port 56a.
[0007]
FIG. 2 is an example of a map selected when the difference between the ambient temperature and the battery temperature is small, and shows allowable values I11 to I66 of the charging current searched according to the battery temperature T and the battery temperature increase value ΔT, and hatched lines. The part indicates an area searched for at the end of charging. That is, a region where the battery temperature rise value ΔT is large (I51 to I66) and a region where the battery temperature T is high and the battery temperature rise value ΔT is medium (I45, I46) are searched at the end of charging.
[0008]
FIG. 3 is an example of a map that is selected when the difference between the ambient temperature and the battery temperature is large. Since the battery temperature increase value ΔT tends to increase, the map lower left region (that is, I41, I42, I51, I52, I61 and I62) are narrowed to increase the resolution of this region. A hatched portion indicates an area searched at the end of charging as in FIG.
[0009]
Next, the operation of the charging device of the present invention will be described with reference to the circuit diagram of FIG. 1 and the flowcharts of FIGS.
[0010]
When the power is turned on, the microcomputer 50 initially sets the output ports 56a and 56b, and enters the connection standby state of the battery set 2 (step 101). When the battery set 2 is connected, the battery temperature T ₁ before the cooling fan 6 is operated is detected from the output of the battery temperature detecting means 2A via the A / D converter 55 (step 102), and then the cooling fan 6 is turned on. The timer is started (step 103) and the timer is started (step 104). After operating the cooling fan 6, and checks whether a predetermined time has elapsed (step 105), if the predetermined time has elapsed, A / D converter from the battery temperature T ₂ at that time the output of the battery temperature detecting means 2A 55 (step 106), the battery temperature T ₂ at the time when a predetermined time has passed and the battery temperature T ₁ before the cooling fan 6 operates are compared and calculated (step 107). Is smaller than the discriminant value, the microcomputer 50 judges that the difference between the ambient temperature and the battery temperature is small, and the microcomputer 50 selects the map of FIG. 2 (step 108), and when the comparison calculation value is larger than the discriminant value, If the microcomputer 50 determines that the difference between the ambient temperature and the battery temperature is large, the microcomputer 50 selects the second map in FIG. 3 (step 109). Battery temperature Charging can be performed without causing premature disconnection due to the determination that the battery is fully charged due to a rapid rise.
[0011]
Charging is started after selecting the map (step 110), the battery temperature T being charged is detected from the output of the battery temperature detecting means 2A at predetermined intervals (step 111), and the temperature rise value ΔT is obtained (step 112). Based on the battery temperature value T and the temperature increase value ΔT, the microcomputer 50 searches the map to obtain an allowable current value of the charging current that can be charged while suppressing the temperature increase.
[0012]
Next, the microcomputer 50 determines whether or not the retrieved allowable value has entered the end-of-charge region indicated by the hatched portion in the map selected in FIG. 2 or FIG. 3 (step 114). When it does not enter the end-of-charge region, the process proceeds to step 115, continues charging with the allowable value obtained in step 113, and returns to step 111. When entering the end-of-charge region, it is determined whether or not the probability of entering the end-of-charge region is high (step 116). For example, when entering the end-of-charge region for three consecutive cycles, it is determined that the probability of entering the end-of-charge region is high. Even if the charging end period is entered, if the three-cycle continuous charging end stage is not entered, it is not determined that the probability of entering the charging end period is high, and the process returns to step 111 via step 115. If the three-cycle continuous charging end region is entered, it is determined that the probability of entering the charging end region is high, and charging is completed (step 117).
[0013]
As described above, in the above-described embodiment, the cooling fan 6 is operated for a predetermined time before starting charging, and the wind at a temperature corresponding to the ambient temperature is applied to the battery set 2, so that the battery temperature T ₂ is set to the ambient temperature. The temperature is close and corresponds to the ambient temperature. Accordingly, the battery temperature and the ambient temperature can be detected only by the battery temperature detection means 2A in the battery set 2, and it is not necessary to add a new temperature detection means for detecting the ambient temperature, and the configuration is simplified.
[0014]
The map in FIG. 3 is selected when it is determined that the ambient temperature is higher than the battery temperature in step 109 of the above embodiment, but the present invention is not limited to this. For example, the temperature rise indicated by the hatched portion in the map as shown in FIG. There may be a map in which the region where the value ΔT is large and the end-of-charge region where the battery temperature T is high and the temperature rise value ΔT is medium are narrowed.
[0015]
【The invention's effect】
As described above, according to the present invention, when the ambient temperature is higher than the battery temperature, the temperature rise value increases due to the temperature gradient between the battery temperature and the ambient temperature immediately after the start of charging, and as a result, the charging due to this temperature rise. The lack of charging due to premature disconnection is eliminated, and reliable full charge determination becomes possible.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of a charging device of the present invention.
FIG. 2 is an explanatory diagram showing the contents of an example of a map selected when the difference between the ambient temperature and the battery temperature is small.
FIG. 3 is an explanatory diagram showing the contents of an example of a map selected when the difference between the ambient temperature and the battery temperature is large.
FIG. 4 is a flowchart for explaining the operation of the charging device of the present invention.
FIG. 5 is an explanatory diagram showing the contents of another example of a map selected when the difference between the ambient temperature and the battery temperature is large.
[Explanation of symbols]
2 is a battery set, 2A is a battery temperature detecting means, 6 is a cooling fan, and 50 is a microcomputer.

Claims

Multiple maps corresponding to the temperature difference between the ambient temperature and the battery temperature are stored in correspondence with the battery temperature and the battery temperature rise value, and the allowable charging current values that can be charged while suppressing the battery temperature rise value are stored. Storage means;
A battery temperature detecting means for detecting the battery temperature, a battery temperature increase value detecting means for calculating an increase value of the battery temperature for each predetermined period based on the output of the battery temperature detecting means, a cooling fan for cooling the battery, and before charging A control unit that operates the cooling fan for a predetermined time to obtain a difference in battery temperature before and after cooling, and selects the map corresponding to the difference, and determines an allowable value of a charging current in the selected map as the battery temperature and A charging device characterized in that a search is performed according to a battery temperature rise value, and charging is performed according to the searched allowable value.

Multiple maps corresponding to the temperature difference between the ambient temperature and the battery temperature are stored in correspondence with the battery temperature and the battery temperature rise value, and the allowable charging current values that can be charged while suppressing the battery temperature rise value are stored. Storage means; battery temperature detection means for detecting battery temperature; battery temperature increase value detection means for calculating an increase value of the battery temperature for each predetermined period based on the output of the battery temperature detection means;
Completion of charging based on whether the battery temperature detected by the battery temperature detection means and the battery temperature increase value detected by the battery temperature rise detection means frequently belong to an area indicating the end of charge in the map. A charging completion determining means for determining, a cooling fan for cooling the battery, a control means for operating the cooling fan for a predetermined time before charging to determine a difference in battery temperature before and after cooling, and selecting the map corresponding to this difference And searching for an allowable value of the charging current in the selected map in accordance with the battery temperature and the battery temperature rise value, and charging based on the searched allowable value and determining completion of charging by the charging completion determining means. A charging device characterized by that.