JP2005189902A - Load adaptive controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a load adaptive controller having a simple configuration for smoothly and stably operating against various loads or a great change in a load. <P>SOLUTION: A device adapting to a change in a load connected to an output end and purposefully operating so as not to change an output property of the device is provided with a load estimation part estimating a load and a control part controlling the device by using a bumpless switch means having a hysteresis characteristic so that the device adapts to the load estimated by the load estimation apparatus for purposeful operation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

ただし、

なお、ｃ_ｍはキャリア信号振幅である。
【００３１】
上記の状態方程式は無負荷状態のものであったが、図１の電圧出力型ＰＷＭ電力増幅器１にキャパシタ負荷Ｃ_Ｌを接続した場合の状態方程式は次式のようになる。

【００３２】
図２は制御対象である電圧出力型ＰＷＭ電力増幅器１をブロック図で表したものであり、電流取得手段である電流推定器２０１と負荷推定器２０２とに分けて考えることができる。
【００３３】
本実施形態では、前述のＨモード又はＬモードは負荷に接続されたキャパシタの容量によって切り換えているため、負荷キャパシタの値を知る必要がある。
【００３４】
この負荷キャパシタの推定に際して、本実施形態では図２の電流推定器２０１により、得られるインダクタＬｏに流れる電流ｉ_０及び出力電圧ｖを用いて、負荷のキャパシタンスを推定している。
【００３５】
図２において、ｕは電圧出力型ＰＷＭ電力増幅器への操作量であり、ｉ_０は電流推定出力（インダクタＬ_０電流）であり、ｙは電圧出力型ＰＷＭ電力増幅器の出力電圧ｖである。以下では電流値取得手段、電流推定器、負荷推定器について詳細に説明する。
【００３６】
＜電流値取得手段＞
通常、電流値は電流センサを用いて検出するが、電流センサは高価な上に取付けスペースも必要なため、本実施形態では電流センサを用いずにインダクタＬ_０に流れる電流ｉ_０を推定している。
【００３７】
＜電流推定器＞
図３は電流推定器２０１の具体的な回路である。図１のＰＷＭ電力増幅器１への操作量ｕと、ＰＷＭ電力増幅器１からの出力電圧ｖを利用して、ＰＷＭ電力増幅器１の出力に接続されているＬＣフィルタのインダクタＬｏに流れる電流を推定する。操作量ｕは非反転増幅器Ｕ２でゲインの調整が行われ、出力電圧ｖからの信号は反転増幅回路Ｕ１で極性の反転及びゲインの調整が行われる。そして、それらの信号をＵ３で加算・積分してインダクタＬ_０電流ｉ_０を得ている。
【００３８】
＜負荷推定器＞
図１の電圧出力型ＰＷＭ電力増幅器１のインダクタＬｏに流れる電流をｉ_０、出

Ｃとすると、その容量値Ｃは次式により推定できる。

ここで、ＣはＣｏと負荷の容量ＣＬとの和、Ｃ＝Ｃ_０＋Ｃ_Ｌである。そして、インダクタＬｏに流れる電流ｉ_０は電流推定器２０１により得られ、ｃ_０は既知であるため、この演算を行うことによりＣ_Ｌを推定できる。
【００３９】

回路、乗算回路を用いて実現したものである。
【００４０】
＜バンプレス切換器＞
一般に増幅器を設計する場合、広範囲な負荷の値に対し最適な動作状態を保たせることは困難である。通常は、ある範囲の負荷の値に対し、増幅器の動作が最適になるよう内部パラメータを決めている。したがって、前記以外の負荷の値に対しては、それらの値に対して最適化された内部パラメータを有する別の増幅器を用意しなければならなかった。
【００４１】
このため、負荷の値が大幅に違っている場合、それぞれの負荷に対して常に最適動作を行うためには、使用するそれぞれの負荷に応じて増幅器を交換する必要があった。もし、これに反して広範な負荷の値を１種類の増幅器で賄おうとしても、オーバーシュートやリンギング発生等の問題が生じて満足な結果が得られなかった。
【００４２】
また、動作時に増幅器の負荷の値を切り換えると、増幅器に外乱が加わったことと等価であるため、出力には切換バンプが発生してしまった。
【００４３】
以上のような問題点を避けるため、本実施形態では、増幅器１の外部に、負荷の範囲に応じて動作するモード（本実施形態ではＨモード及びＬモードの２モードとしている。この「Ｈ」はＨｉｇｈに、「Ｌ」はＬｏｗにそれぞれ対応している）を設け、このモードを負荷の値によって切り換えている。すなわち、図１において、加減算器３により得られた、入力（目標）ｒと出力ｖとの差信号がＨモード制御器４とＬモード制御器５に入力される。Ｈモード制御器４とＬモード制御器５の出力は、モード切換器６に入力され、負荷推定器２０２で得られた負荷に応じていずれかのモード制御器からの信号が選択され操作量ｕとしてＰＷＭコンパレータ１２と負荷推定器２０２に入力される。負荷推定器２０２には出力電圧ｖも入力されている。加減算器７と８には、Ｈモード制御器４とＬモード制御器５の出力と、モード切換器６の出力（操作量ｕ）とが入力されている。こうして、未選択モードは待期中に現在の操作量ｕ（現在選択されているモードが出す操作量）と自身の操作量を比較し、現在の操作量に近づけるような動作が実行される。
【００４４】
各モードでのキャパシタ負荷値に対応する出力電圧ｖのステップ応答が図５（Ａ）〜（Ｄ）に示されている。同図（Ａ）はＬモード（負荷キャパシタンスＣ_Ｌ＝１０ｕＦ）での応答を、同図（Ｂ）はＬモード（負荷キャパシタンスＣ_Ｌ＝５０ｕＦ）での応答を、同図（Ｃ）はＨモード（負荷キャパシタンスＣ_Ｌ＝１０ｕＦ）での応答を、同図（Ｄ）はＨモード（負荷Ｃ_Ｌキャパシタンス＝５０ｕＦ）での応答をそれぞれ示す。
【００４５】
同図から明らかなように、負荷キャパシタンスＣ_Ｌ＝１０ｕＦの場合には、（Ａ）のようにＬモードで動作させると目標動作を維持できるが、負荷キャパシタンス５０ｕＦになると、（Ｂ）のようにＬモードではオーバーシュート動作してしまう。一方、負荷キャパシタンスが１０ｕＦでＨモードで動作させた場合には、（Ｃ）のようにリンギングが発生してしまうが、負荷キャパシタンス５０ｕＦではＨモードで、（Ｄ）のような目標動作が得られる。
【００４６】
したがって、負荷キャパシタンスの値に応じてＬモードとＨモード動作を適宜選択すれば、目標動作が確保できることになる。
【００４７】
ここで、本実施形態のように、ＬモードとＨモードの２つのモードではなく、負荷範囲に応じた数のモードを設定すれば、より広範囲の容量性負荷に対する制御が可能となることはもちろんである。
【００４８】
ところで、通常、モード切換を行うと図１の操作量ｕが急激な変化を起こし制御対象（ＰＷＭ電力増幅器）１もこれに応答し、出力にはバンプ（切換ショック）が発生する。バンプレス切換は、待機中のモードから出力される操作量を現在選択されているモードから出力される操作量とほぼ一致するように待機させ、切換時に操作量ｕの変化量が小さくなるようにすることにより実現させる。
【００４９】
このようなモード切換を行うと、負荷変動があっても増幅器の出力にはその影響（バンプ）が現れない、いわゆるバンプレス機能を有する増幅器を実現できる。負荷の値は前述のようにして推定できるので、この推定値によってどのモードを使うかを図１の切換スイッチ６により選択している。
【００５０】
＜ヒステリシス動作＞
図１の切換スイッチ６は、図６に示すように推定キャパシタ値がＴＨ−Ｈを超えるとＬモードからＨモードに切り換わる。また反対に、推定キャパシタ値が設定値ＴＨ−Ｌより小さくなるとＨｉｇｈモードからＬｏｗモードに切り換わる。
【００５１】
このように推定された負荷キャパシタ値によりモードを切り換えるが、推定キャパシタ値が切換の閾値に近いときにノイズの影響などによって推定値が変動すると、頻繁にモードが切り換わる不具合が発生する。このため、切換特性に図６に示すようなヒステリシスを設ける。
【００５２】
Ｌモードが選択されている場合、閾値がＴＨ−Ｌを超えてもすぐにはＨモードにならず、閾値がＴＨ−Ｈを超えて初めてＨモードに切り換わる。一方、推定キャパシタ値がＴＨ−Ｌを下回ると直ちにＨモードからＬモードへと切り換わる。ここで、（ＴＨ−Ｈ − ＴＨ−Ｌ）はヒステリシス幅であり、前述した通り、推定キャパシタ値のノイズ等による誤動作を防ぐためのものである。ＵＨはＨモード制御器の出力であり、ＵＬはＬモード制御器の出力である。Ｌモード時は、Ｈモード制御器の出力はＬモード制御器の出力に追従する構成となっている。Ｈモード時はその逆である。この構成によって、モード切換時に出力電圧にバンプを発生しないバンプレス切換が可能となる。
【００５３】
尚、図４において、Ｃ_０＝０と置けば、Ｃ_０が無い場合にも適用できる。
【００５４】
《他の実施形態》
以上述べた実施形態は、定電圧増幅器に負荷としてキャパシタを用いた場合である。これに対して、定電流増幅器の場合、負荷インダクタンス変動の影響が大きい。そこで、以下の実施形態では、インダクタンス負荷の定電流増幅器として制御されたＰＷＭ式フルブリッジ電圧型インバータの例を図７を参照しながら説明する。
【００５５】
図７は本発明の他の実施形態による定電流増幅器（ＰＷＭ式フルブリッジ電圧型インバータ使用）の負荷適応型制御装置の回路図である。
【００５６】
図７はそのようなバンプレス機能を持つ負荷適応型制御装置の実施形態であり、制御対象であるＰＷＭ電力増幅器１Ａ、電流推定器２０１Ａ、負荷推定器２０２Ａ、加減算器３Ａ、Ｈモード制御器４Ａ、Ｌモード制御器５Ａ、Ｈモード及びＬモードの各制御器４Ａと５Ａの出力を切り換えるモード切換器（ＳＷ）６Ａ、加減算器７Ａと８Ａを含んだ待機モードの出力と選択モードの出力が近い値となるように補助をするＨモード及びＬモードバンプレス補助切換器１３、１４を備える。本実施形態において、ＰＷＭ電力増幅器１Ａの出力１０Ａ、１０Ａ’には負荷としてインダクタンスＬ_Ｌが接続されている。
【００５７】
図７において、ＰＷＭ電力増幅器１Ａは、図１と同様な直流電源Ｅが接続されているＦＥＴ１〜ＦＥＴ４によるフルブリッジ回路１１Ａと、インダクタンスＬ_０、キャパシタＣ_０からなるＬＣフィルタとを含み、このＬＣフィルタの出力にインダクタンスＬ_１が接続されるとともに、負荷としてインダクタンスＬ_Ｌが接続されている。ここで、インダクタンスＬ_０に流れる電流をｉ_０、出力１０Ａ−１０Ａ’の電圧をｖ、キャパシタＣ_０の電圧をｅ_０とする。
【００５８】
フルブリッジ回路１１Ａを構成するＦＥＴ１〜ＦＥＴ４の各ゲートはＰＷＭコンパレータ１２Ａにより駆動される。ＰＷＭコンパレータ１２Ａは、入力される操作量ｕを図示のような波形のキャリアと比較し、比較出力によりＦＥＴ１〜ＦＥＴ４の各ゲートへの印加電圧が制御される。
【００５９】
さて、図７に示すように、制御対象に負荷インダクタンスが接続されたときの状態方程式を以下のようになる。また、この式は図８のような状態線図で表すことができる。

【００６０】
＜電流推定部＞
図１において説明した動作で電流が推定されるが、その詳細は前述したとおりである。
【００６１】
＜負荷推定部＞
図７のＰＷＭ電力増幅器にインダクタンス負荷Ｌ_Ｌが接続されているとき、そのＬ＝Ｌ_１＋Ｌ_Ｌの値は図中のｅ_０とｉとから次の式で表される。

【００６２】
図９はインダクタンス負荷の推定器のブロック図であり、上記の式を微分回路、逆数回路、乗算回路を用いて実現したものである。図中のｅ_０、ｙ＝ｉは、図８のｅ_０、ｙ＝ｉにそれぞれ対応している。先の実施例と同様に負荷インダクタンスを推定できる。
【００６３】
＜バンプレス切換器およびヒステリシス動作＞
前述の式により推定されたインダクタンスの値によって、前述実施形態と同様にモードは切換えられる。もし、インダクタンスの値が切換の境界付近の値をとるならば、モード切換において問題が生じる。それ故、本実施例でも図６に示すのと同様なヒステリシス特性を持たせている。動作の説明については第１の実施例と同様なため省略する。
【００６４】
図１０と図１１にバンプレス切換を適用しない場合と、適用した場合の出力のシミュレーション波形例を示す。このシミュレーションでの切換時間は２ｍｓであり、Ｌモード→Ｈモードのように切り換わっているが、バンプレス切換を適用した場合（図１１）は、出力にバンプは現れていない。
尚、Ｌ_０、Ｃ_０が無い場合には、ｅ_０＝ｕ・Ｋ_ｐとなり、Ｌ_０、Ｃ_０が無い場合にも適用できる。更に、Ｌ_１＝０と置けば、Ｌ_０、Ｃ_０、Ｌ_１が無い場合にも適用できる。
【００６５】
抵抗性負荷の場合は、例えば、図１に示した実施形態のＣ_ＬをＲ_Ｌ（抵抗性負荷）に置き換えたものとなる。この場合のｉ_０の推定は容量性負荷と同様となる。負

により行う。
【００６６】
種類が不明である場合にも本発明は有効である。例えば、負荷を容量性と仮定した場合、誘導性と仮定した場合、抵抗性と仮定した場合の各値を、先に説明したような方法を用いてそれぞれ推定する。そして、出力特性に影響を及ぼす可能性の最も高い値に対応したモードに切り換えることにより、負荷適応型制御が可能となる。
【００６７】
以上、本発明の好適実施形態例を説明したが、これは単なる例示にすぎず、特定用途に応じて種々の変形変更が可能であること勿論である。
【００６８】
【発明の効果】
以上のように、本発明では、装置内に、変化する負荷を推定する負荷推定部と、推定された負荷範囲に応じて制御パラメータをヒステリシス特性をもつバンプレスな切換手段で制御しているので、簡単な構成で、種々の負荷に対して、または大幅な負荷変動に対して、スムーズ且つ安定な動作を確保可能で、負荷適応型制御を実現できる。
【００６９】
より具体的には、本発明によれば、容量性負荷のシステムにおいて、運転中に負荷推定を行い、この推定値によりモードをバンプレスに切り換えているので、出力に接続された負荷の値がリアルタイムに変動しても、出力にバンプを生じることのない、負荷適応型制御が実現できる。
【００７０】
また、誘導性負荷または抵抗性負荷のシステムにおいて、運転中に負荷推定を行い、この推定値によりモードをバンプレスに切り換えている。これにより、容量性負荷の場合と同様に負荷適応型制御を実現した。
【００７１】
更に、従来は負荷の種類や負荷範囲に応じて多種類の電源やアンプを用意しておく必要があったが、本発明によれば大幅に電源やアンプの種類を減らすことができる。
【図面の簡単な説明】
【図１】本発明の一実施形態におけるキャパシタンス負荷を有するＰＷＭ電力増幅器に適用した負荷適応型制御装置の回路構成図である。
【図２】本発明の実施形態における状態線図と電流推定器及び負荷推定器を示す図である。
【図３】本発明の実施形態における電流推定器の具体的な回路図である。
【図４】本発明の実施形態における容量推定器のブロック構成図である。
【図５】本発明の実施形態におけるＬモードとＨモードでの増幅器５のキャパシタ負荷値に対応する応答動作図である。
【図６】本発明の実施形態における切換部のヒステリシス特性である。
【図７】本発明の一実施形態におけるインダクタンス負荷を有するＰＷＭ電力増幅器に適用した負荷適応型制御装置の回路構成図である。
【図８】図７に示す本発明の実施形態における状態線図と電流推定器及び負荷推定器を示す図である。
【図９】図７に示す本発明の実施形態におけるインダクタンス推定器のブロック図である。
【図１０】本発明の効果を説明するための図で、バンプレス切換無しの場合の出力波形である。
【図１１】本発明の効果を説明するための図で、バンプレス切換ありの場合の出力波形である。
【図１２】従来の定電圧増幅器の問題点を説明するための動作状態を示す図である。
【符号の説明】
１、１Ａ ＰＷＭ電力増幅器
３、３Ａ、７、７Ａ、８、８Ａ 加減算器
４、４Ａ Ｈモード制御器
５、５Ａ Ｌモード制御器
６、６Ａ モード切換器
１１、１１Ａ フルブリッジ
１２、１２Ａ ＰＷＭコンパレータ
１３、１３Ａ Ｈモード側バンプレス補助切換器
１４、１４Ａ Ｌモード側バンプレス補助切換器
２０１、２０１Ａ 電流推定器
２０２、２０２Ａ 負荷推定器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a load adaptive control apparatus, for example, a load adaptive control apparatus that adapts to a load connected to an amplifier or a power supply and ensures a target operation.
[0002]
[Prior art]
Conventionally, when a load is connected to an amplifier, it has been necessary to connect a load of type and value (optimum load) defined in the specification in order to maximize the performance of the amplifier such as frequency characteristics. If the load connected to the amplifier is not optimal in this way, a quick and accurate response output to the input cannot be obtained, overshooting or ringing occurs, and the time until reaching the target value becomes long. Occur. On the other hand, in an amplifier to which an optimum load is connected, the output can quickly reach the target value without overshoot or ringing with respect to the step input (target value).
[0003]
FIG. 12 shows the operating state of such an amplifier. When a step-like signal as shown in FIG. 12A is input to the amplifier, when the load is a rated load (optimum load), as shown in FIG. The rated load response is reached to reach the corresponding target value. On the other hand, when the load deviates greatly from the rating, the output amplitude of the amplifier output oscillates until the target value is reached and the arrival time becomes longer as shown in FIG. End up.
[0004]
[Problems to be solved by the invention]
As described above, in a conventional amplifier, if a load other than the rated load (type and value) specified in the specifications is used, the response of the amplifier is not guaranteed, and for example, overshoot or ringing occurs in the output waveform. There was a problem that.
[0005]
For example, the amplifier is normally controlled by PID control, and when a load other than the rated load is connected, the amplifier deviates from the optimum control, and the required specification cannot be satisfied. As an example, in the case of a constant voltage amplifier, the influence of the capacitive load is large, and in cases other than the rated capacity, ringing occurs or oscillation occurs at worst.
[0006]
In order to avoid such a problem, conventionally, another amplifier capable of handling a load other than the rated value has to be prepared.
[0007]
In addition, an amplifier has been proposed in which an internal parameter that defines an operational state of an amplifier corresponding to a connected load value is manually switched to an appropriate value according to the connected load. However, in this type of amplifier, although it is not necessary to prepare a new amplifier, a troublesome work of manually switching the set value according to the value of the load is necessary. Further, when the set value is switched, a bump occurs in the output of the amplifier.
[0008]
In addition, some amplifiers are controlled to be stable over a wide range of load fluctuations using PID control using modern control theory. However, in this case, there is a limit in that an unrealistic parameter setting is required to cope with a wider range of load fluctuations.
[0009]
SUMMARY OF THE INVENTION An object of the present invention is to provide a load adaptive control apparatus that can ensure a smooth and stable operation with various loads or a large load fluctuation with a simple configuration.
[0010]
Another object of the present invention is to provide a load adaptive control device that realizes bumpless switching with a simple configuration without generating a bump (switching shock) even when the connected load is switched. is there.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problem, the load adaptive control apparatus according to the present invention employs the following characteristic configuration.
[0012]
(1) In a device that performs a target operation so as not to change the output characteristics of the device in response to a change in the load connected to the output terminal,
A load estimator provided in the apparatus for estimating the load;
A controller that robustly controls the device to adapt to the load estimated by the load estimator and perform a target operation;
A load adaptive control device comprising:
[0013]
(2) The load adaptive control device according to (1), wherein the control unit controls the operation condition so that the device performs a target operation when the load varies.
[0014]
(3) The load adaptive control apparatus according to (2), wherein the control of the control unit has a switching means.
[0015]
(4) The load adaptive control device according to (3), wherein the switching unit controls the output so as not to cause a bump.
[0016]
(5) The load adaptive control device according to (3), wherein the switching means has a hysteresis characteristic at the time of switching.
[0017]
(6) The device is an amplifier including an inductor on an output side, the load is capacitive, and the load estimation unit uses the current flowing through the inductor and a differential value of an output voltage to The load adaptive control apparatus according to any one of (1) to (5), wherein the load characteristic estimation is performed.
[0018]
(7) The device is an amplifier including an inductor on an output side, the load is inductive, and the load estimation unit includes a differential value of a current flowing through the inductor, the inductor, and the inductive load. The load adaptive control device according to any one of (1) to (5), wherein the inductive load value is estimated using the voltage across the series circuit.
[0019]
(8) The device is an amplifier including an inductor and a capacitor on an output side, the load is resistive, and the load estimation unit uses a current flowing through the inductor and a differential value of the output voltage. The load adaptive control device according to any one of (1) to (5), wherein the resistive load value is estimated.
[0020]
(9) The apparatus is an amplifier including an inductor on an output side, the load is resistive, and the load estimating unit includes a differential value of a current flowing through the inductor, the inductor, and the resistive load. The load adaptive control device according to any one of the above (1) to (5), wherein the resistance load value is estimated using the voltage across the series circuit.
[0021]
(10) An input signal is supplied to the capacitive load connected to the output terminal to supply an output voltage or current corresponding to the input signal, an inductor is connected to the output terminal, and the capacitive load is in operation In a variable load adaptive control device,
Current value obtaining means for obtaining a current flowing through the inductor;
Load estimation means for estimating the capacitive load value using the current value obtained by the current value acquisition means and the differential value of the output voltage;
A load adaptive control device comprising: parameter switching means for switching an internal control parameter so that a bump does not occur in an output when the capacitive load fluctuates in accordance with a load value estimated by the load estimation means.
[0022]
(11) An output voltage or current corresponding to the input signal is supplied to the inductive load connected to the output terminal in response to the input signal, an inductor is connected to the inside of the output terminal, and the inductive load is in operation In a variable load adaptive control device,
Current value obtaining means for obtaining a current flowing through the inductor;
Load estimation means for estimating the inductive load value using a differential value of the current obtained by the current value acquisition means and a voltage across a series circuit of the inductor and the inductive load;
A load adaptive control device comprising: a parameter switching unit that switches an internal control parameter so that a bump does not occur in an output when the inductive load fluctuates in accordance with a load value estimated by the load estimation unit.
[0023]
(12) An output voltage or current corresponding to the input signal is supplied to a resistive load connected to the output terminal in response to the input signal, an inductor and a capacitor are connected inside the output terminal, and the resistive load is operated. In a load adaptive control device that fluctuates during
Current value obtaining means for obtaining a current flowing through the inductor;
Load estimation means for estimating the resistive load value using the current value obtained by the current value acquisition means and the differential value of the output voltage;
A load adaptive control device comprising: parameter switching means for switching an internal control parameter so as not to cause a bump when the resistive load changes according to a load value estimated by the load estimation means.
[0024]
(13) An output voltage or current corresponding to the input signal is supplied to a resistive load connected to the output terminal in response to the input signal, an inductor is connected to the inside of the output terminal, and the resistive load is in operation In a variable load adaptive control device,
Current value obtaining means for obtaining a current flowing through the inductor;
Load estimation means for estimating the resistive load value using a differential value of the current obtained by the current value acquisition means and a voltage across a series circuit of the inductor and the resistive load;
A load adaptive control device comprising: parameter switching means for switching an internal control parameter so as not to cause a bump when the resistive load changes according to a load value estimated by the load estimation means.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of a load adaptive control device according to the present invention will be described in detail with reference to the accompanying drawings.
[0026]
FIG. 1 is a circuit configuration diagram when a PWM full-bridge voltage type inverter is a constant voltage amplifier and two controllers are used as an embodiment of the present invention. The present invention will be described with reference to this figure. The present invention is not limited to this embodiment.
[0027]
FIG. 1 shows a preferred embodiment of a load adaptive control device having such a bumpless function. The voltage output type PWM power amplifier 1, current estimator 201, load estimator 202, adder / subtractor 3, H Standby mode output and selection mode including a mode controller 4, an L mode controller 5, a mode switch (SW) 6 for switching the outputs of the controllers 4 and 5 in the H mode and the L mode, and adders 7 and 8 H-mode and L-mode bumpless auxiliary switchers 13 and 14 for assisting so that the output of the output becomes a close value. In the present embodiment, a capacitor _CL is connected as a load to the outputs 10 and 10 ′ of the voltage output type PWM power amplifier 1.
[0028]
In FIG. 1, a voltage output type PWM power amplifier 1 includes a full bridge circuit 11 composed of FET1 to FET4 to which a DC power source E is connected, and an LC filter composed of an inductance Lo and a capacitor Co. The output of this LC filter is The output terminal of the voltage output type PWM amplifier 1 to which the capacitor _CL is connected as a load. The current flowing through the inductance Lo is i ₀ and the voltage v of the output 10-10 ′. Thus, in this embodiment, the capacitor is connected as the load of the voltage output type PWM amplifier 1.
[0029]
Each gate of FET1 to FET4 constituting the full bridge circuit 11 is driven by a PWM comparator 12. The PWM comparator 12 compares the input operation amount u with a carrier having a waveform as shown in the figure, and the applied voltage to each gate of the FET1 to FET4 is controlled by the comparison output.
[0030]
Now, the state equation of the voltage output type PWM power amplifier 1 shown in FIG. 1 when there is no load is as follows.

However,

Note that _cm is the carrier signal amplitude.
[0031]
The above state equation is in a no-load state, but the state equation when the capacitor load _CL is connected to the voltage output type PWM power amplifier 1 of FIG.

[0032]
FIG. 2 is a block diagram showing the voltage output type PWM power amplifier 1 to be controlled, and can be divided into a current estimator 201 and a load estimator 202 as current acquisition means.
[0033]
In the present embodiment, since the H mode or the L mode is switched according to the capacitance of the capacitor connected to the load, it is necessary to know the value of the load capacitor.
[0034]
In estimating the load capacitor, in the present embodiment, the current estimator 201 in FIG. 2 estimates the load capacitance using the current i ₀ and the output voltage v flowing through the obtained inductor Lo.
[0035]
In FIG. 2, u is an operation amount to the voltage output type PWM power amplifier, i ₀ is a current estimation output (inductor L ₀ current), and y is an output voltage v of the voltage output type PWM power amplifier. Hereinafter, the current value acquisition unit, the current estimator, and the load estimator will be described in detail.
[0036]
<Current value acquisition means>
Usually, the current value is detected using a current sensor, for installation space also needed on the current sensor is expensive, in the present embodiment to estimate the current i ₀ flowing through the inductor L ₀ without using a current sensor Yes.
[0037]
<Current estimator>
FIG. 3 shows a specific circuit of the current estimator 201. The current flowing through the inductor Lo of the LC filter connected to the output of the PWM power amplifier 1 is estimated using the operation amount u to the PWM power amplifier 1 in FIG. 1 and the output voltage v from the PWM power amplifier 1. . The manipulated variable u is adjusted in gain by the non-inverting amplifier U2, and the signal from the output voltage v is inverted in polarity and adjusted in gain by the inverting amplifier circuit U1. Then, to obtain the inductor L ₀ current i ₀ by adding and integration of those signals in U3.
[0038]
<Load estimator>
The current flowing through the inductor Lo of the voltage output type PWM power amplifier 1 in Figure 1 _{i 0,} out

Assuming that C, the capacitance value C can be estimated by the following equation.

Here, C is the sum of the capacitance CL of the load and Co, a _{C = C} 0 + _{C L.} Then, the current i ₀ flowing through the inductor Lo is obtained by the current estimator 201, c ₀ is because it is known, can estimate the C _L by performing this operation.
[0039]

This is realized by using a circuit and a multiplication circuit.
[0040]
<Bumpless switcher>
In general, when designing an amplifier, it is difficult to maintain an optimum operating state over a wide range of load values. Usually, the internal parameters are determined so that the operation of the amplifier is optimal for a certain range of load values. Therefore, for other load values, a separate amplifier had to be prepared with internal parameters optimized for those values.
[0041]
For this reason, when the load values are significantly different, it is necessary to replace the amplifier in accordance with each load to be used in order to always perform the optimum operation for each load. On the other hand, even if an attempt was made to cover a wide range of load values with one type of amplifier, problems such as overshoot and ringing occurred, and satisfactory results could not be obtained.
[0042]
In addition, switching the load value of the amplifier during operation is equivalent to a disturbance applied to the amplifier, so that a switching bump occurs in the output.
[0043]
In order to avoid the problems as described above, in the present embodiment, a mode that operates according to the load range is provided outside the amplifier 1 (in this embodiment, two modes, an H mode and an L mode. This “H”. , “L” corresponds to “Low”, and “L” corresponds to Low), and this mode is switched according to the load value. That is, in FIG. 1, the difference signal between the input (target) r and the output v obtained by the adder / subtractor 3 is input to the H mode controller 4 and the L mode controller 5. Outputs of the H mode controller 4 and the L mode controller 5 are input to the mode switch 6, and a signal from one of the mode controllers is selected according to the load obtained by the load estimator 202, and the manipulated variable u As input to the PWM comparator 12 and the load estimator 202. An output voltage v is also input to the load estimator 202. The outputs of the H mode controller 4 and L mode controller 5 and the output (operation amount u) of the mode switch 6 are input to the adders / subtracters 7 and 8. In this way, in the unselected mode, the current operation amount u (the operation amount output by the currently selected mode) is compared with its own operation amount during the waiting period, and an operation that approaches the current operation amount is executed.
[0044]
The step response of the output voltage v corresponding to the capacitor load value in each mode is shown in FIGS. Responding in Fig (A) is L mode (load capacitance _C L = 10uF), the response in FIG. (B) is L mode (load capacitance _C L = _50uF), FIG (C) is H mode the response at (load capacitance _C L = 10uF), FIG. (D) denotes a response in H-mode (load _{C L} capacitance = 50uF).
[0045]
As can be seen from the figure, when the load capacitance C _L = 10 uF, the target operation can be maintained by operating in the L mode as shown in (A), but when the load capacitance is 50 uF, as shown in (B). In L mode, an overshoot operation occurs. On the other hand, when the load capacitance is 10 uF and operated in the H mode, ringing occurs as shown in (C), but with the load capacitance of 50 uF, the target operation as shown in (D) can be obtained in the H mode. .
[0046]
Therefore, the target operation can be secured by appropriately selecting the L mode and the H mode operation according to the value of the load capacitance.
[0047]
Here, as in this embodiment, if a number of modes according to the load range is set instead of the two modes of the L mode and the H mode, it is possible to control a wider range of capacitive loads. It is.
[0048]
Normally, when the mode is switched, the manipulated variable u in FIG. 1 undergoes a sudden change, and the controlled object (PWM power amplifier) 1 also responds to this, and a bump (switching shock) occurs in the output. In bumpless switching, the operation amount output from the standby mode is made to wait so that it substantially matches the operation amount output from the currently selected mode, and the change amount of the operation amount u is reduced at the time of switching. To make it happen.
[0049]
By performing such mode switching, it is possible to realize an amplifier having a so-called bumpless function in which the influence (bump) does not appear in the output of the amplifier even if there is a load change. Since the load value can be estimated as described above, the mode to be used is selected by the changeover switch 6 in FIG. 1 based on the estimated value.
[0050]
<Hysteresis operation>
As shown in FIG. 6, the changeover switch 6 in FIG. 1 switches from the L mode to the H mode when the estimated capacitor value exceeds TH-H. On the other hand, when the estimated capacitor value becomes smaller than the set value TH-L, the high mode is switched to the low mode.
[0051]
The mode is switched according to the load capacitor value estimated as described above. However, when the estimated value fluctuates due to the influence of noise or the like when the estimated capacitor value is close to the switching threshold value, there is a problem that the mode is frequently switched. For this reason, hysteresis as shown in FIG. 6 is provided in the switching characteristics.
[0052]
When the L mode is selected, the H mode is not immediately entered even if the threshold exceeds TH-L, and the mode is switched to the H mode only after the threshold exceeds TH-H. On the other hand, when the estimated capacitor value falls below TH-L, the mode immediately switches from the H mode to the L mode. Here, (TH−H−TH−L) is a hysteresis width, and as described above, is for preventing malfunction due to noise or the like of the estimated capacitor value. UH is the output of the H mode controller, and UL is the output of the L mode controller. In the L mode, the output of the H mode controller follows the output of the L mode controller. The reverse is true in H mode. With this configuration, it is possible to perform bumpless switching without generating a bump in the output voltage at the time of mode switching.
[0053]
In FIG. 4, if C ₀ = 0 is set, the present invention can be applied even when C ₀ does not exist.
[0054]
<< Other embodiments >>
The embodiment described above is a case where a capacitor is used as a load in the constant voltage amplifier. On the other hand, in the case of a constant current amplifier, the influence of load inductance fluctuation is large. Therefore, in the following embodiment, an example of a PWM type full bridge voltage type inverter controlled as a constant current amplifier of an inductance load will be described with reference to FIG.
[0055]
FIG. 7 is a circuit diagram of a load adaptive control device for a constant current amplifier (using a PWM full bridge voltage type inverter) according to another embodiment of the present invention.
[0056]
FIG. 7 shows an embodiment of a load adaptive control apparatus having such a bumpless function. The PWM power amplifier 1A, the current estimator 201A, the load estimator 202A, the adder / subtractor 3A, and the H mode controller 4A that are control targets. The output of the standby mode including the L mode controller 5A, the mode switcher (SW) 6A for switching the outputs of the controllers 4A and 5A in the H mode and the L mode, and the adders / subtracters 7A and 8A is close to the output of the selection mode. H-mode and L-mode bumpless auxiliary switching units 13 and 14 are provided to assist the value. In the present embodiment, an inductance _LL is connected as a load to the outputs 10A and 10A ′ of the PWM power amplifier 1A.
[0057]
In FIG. 7, a PWM power amplifier 1A includes a full bridge circuit 11A composed of FET1 to FET4 to which a DC power supply E similar to that in FIG. 1 is connected, and an LC filter composed of an inductance L ₀ and a capacitor C _0. together with the inductance L ₁ is connected to the output of the filter, the inductance L _L is connected as a load. Here, the current flowing through the inductance L ₀ is i ₀ , the voltage of the output 10A-10A ′ is v, and the voltage of the capacitor C ₀ is e ₀ .
[0058]
Each gate of FET1 to FET4 constituting the full bridge circuit 11A is driven by a PWM comparator 12A. The PWM comparator 12A compares the input manipulated variable u with a carrier having a waveform as shown in the figure, and the applied voltage to each gate of the FET1 to FET4 is controlled by the comparison output.
[0059]
Now, as shown in FIG. 7, the equation of state when the load inductance is connected to the controlled object is as follows. Further, this equation can be expressed by a state diagram as shown in FIG.

[0060]
<Current estimation unit>
The current is estimated by the operation described in FIG. 1, and the details thereof are as described above.
[0061]
<Load estimation part>
When the inductance load L _L is connected to the PWM power amplifier of FIG. 7, the value of L = L ₁ + L _L is expressed by the following equation from e ₀ and i in the figure.

[0062]
FIG. 9 is a block diagram of an inductance load estimator, which implements the above equation using a differentiation circuit, an inverse circuit, and a multiplication circuit. E ₀ and y = i in the figure correspond to e ₀ and y = i in FIG. 8, respectively. The load inductance can be estimated as in the previous embodiment.
[0063]
<Bumpless switcher and hysteresis operation>
The mode is switched in the same manner as in the above-described embodiment by the inductance value estimated by the above formula. If the inductance value takes a value near the switching boundary, a problem occurs in mode switching. Therefore, this embodiment also has a hysteresis characteristic similar to that shown in FIG. The description of the operation is the same as that in the first embodiment, and will be omitted.
[0064]
FIGS. 10 and 11 show examples of simulation waveforms of the output when bumpless switching is not applied and when it is applied. The switching time in this simulation is 2 ms, and the mode is switched from L mode to H mode. However, when bumpless switching is applied (FIG. 11), no bump appears in the output.
When L ₀ and C ₀ are not present, e ₀ = u · K _{p is obtained} , and the present invention can be applied even when L ₀ and C ₀ are absent. Furthermore, if L ₁ = 0 is set, the present invention can be applied even when L ₀ , C ₀ , and L ₁ are not present.
[0065]
For resistive loads, for example, the C _L in the embodiment shown in FIG. 1 and replaced with a R _{L (resistive} load). In this case, the estimation of i ₀ is the same as that of the capacitive load. negative

To do.
[0066]
The present invention is also effective when the type is unknown. For example, when the load is assumed to be capacitive, when it is assumed to be inductive, each value when it is assumed to be resistive is estimated using the method described above. Then, by switching to a mode corresponding to the value most likely to affect the output characteristics, load adaptive control can be performed.
[0067]
The preferred embodiment of the present invention has been described above. However, this is merely an example, and it is needless to say that various modifications and changes can be made according to a specific application.
[0068]
【The invention's effect】
As described above, in the present invention, the control parameter is controlled by the load estimating unit for estimating the changing load and the bumpless switching means having the hysteresis characteristic in accordance with the estimated load range. With a simple configuration, it is possible to ensure a smooth and stable operation with respect to various loads or large load fluctuations, and to realize load adaptive control.
[0069]
More specifically, according to the present invention, in a capacitive load system, load estimation is performed during operation, and the mode is switched to bumpless by this estimated value, so that the value of the load connected to the output is Even if it fluctuates in real time, load adaptive control can be realized without causing bumps in the output.
[0070]
Also, in an inductive load or resistive load system, load estimation is performed during operation, and the mode is switched to bumpless based on this estimated value. As a result, the load adaptive control is realized as in the case of the capacitive load.
[0071]
Furthermore, conventionally, it has been necessary to prepare various types of power supplies and amplifiers according to the types of loads and load ranges. However, according to the present invention, the types of power supplies and amplifiers can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram of a load adaptive control device applied to a PWM power amplifier having a capacitance load in an embodiment of the present invention.
FIG. 2 is a diagram showing a state diagram, a current estimator and a load estimator in the embodiment of the present invention.
FIG. 3 is a specific circuit diagram of a current estimator in the embodiment of the present invention.
FIG. 4 is a block configuration diagram of a capacity estimator in the embodiment of the present invention.
FIG. 5 is a response operation diagram corresponding to the capacitor load value of the amplifier 5 in the L mode and the H mode in the embodiment of the present invention.
FIG. 6 is a hysteresis characteristic of the switching unit in the embodiment of the present invention.
FIG. 7 is a circuit configuration diagram of a load adaptive control device applied to a PWM power amplifier having an inductance load according to an embodiment of the present invention.
FIG. 8 is a diagram showing a state diagram, a current estimator and a load estimator in the embodiment of the present invention shown in FIG. 7;
9 is a block diagram of an inductance estimator in the embodiment of the present invention shown in FIG.
FIG. 10 is a diagram for explaining the effect of the present invention, and is an output waveform when bumpless switching is not performed;
FIG. 11 is a diagram for explaining the effect of the present invention and is an output waveform when bumpless switching is performed;
FIG. 12 is a diagram showing an operation state for explaining a problem of a conventional constant voltage amplifier.
[Explanation of symbols]
1, 1A PWM power amplifier 3, 3A, 7, 7A, 8, 8A adder / subtractor 4, 4A H mode controller 5, 5A L mode controller 6, 6A mode switch 11, 11A full bridge 12, 12A PWM comparator 13 , 13A H-mode side bumpless auxiliary switching device 14, 14A L-mode side bumpless auxiliary switching device 201, 201A Current estimator 202, 202A Load estimator

Claims (13)

In a device that operates as a target so as not to change the output characteristics of the device in response to changes in the load connected to the output end,
A load estimator provided in the apparatus for estimating the load;
A controller that robustly controls the device to adapt to the load estimated by the load estimator and perform a target operation;
A load adaptive control apparatus comprising: The load adaptive control device according to claim 1, wherein the control unit controls the operation condition so that the device performs a target operation when the load varies. The load adaptive control apparatus according to claim 2, wherein the control of the control unit includes a switching unit. 4. The load adaptive control apparatus according to claim 3, wherein the switching means controls so as not to generate a bump in the output at the time of switching. 4. The load adaptive control apparatus according to claim 3, wherein the switching means has a hysteresis characteristic at the time of switching. The apparatus is an amplifier including an inductor on an output side, the load is capacitive, and the load estimation unit uses the current flowing through the inductor and a differential value of an output voltage to generate the capacitive load value. The load adaptive control device according to claim 1, wherein the load adaptive control device is estimated. The apparatus is an amplifier including an inductor on an output side, the load is inductive, and the load estimation unit includes a differential value of a current flowing through the inductor, and a series circuit of the inductor and the inductive load. The load adaptive control apparatus according to claim 1, wherein the inductive load value is estimated using a voltage between both ends of the load. The device is an amplifier including an inductor and a capacitor on an output side, the load is resistive, and the load estimating unit uses the current flowing through the inductor and a differential value of an output voltage to perform the resistive operation. 6. The load adaptive control apparatus according to claim 1, wherein the load value is estimated. The apparatus is an amplifier including an inductor on an output side, the load is resistive, and the load estimation unit includes a differential value of a current flowing through the inductor, and a series circuit of the inductor and the resistive load. The load adaptive control apparatus according to claim 1, wherein the resistance load value is estimated using a voltage between both ends of the load. A load that receives an input signal and supplies an output voltage or current corresponding to the input signal to a capacitive load connected to the output terminal, and an inductor is connected inside the output terminal, and the capacitive load fluctuates during operation. In an adaptive controller,
Current value obtaining means for obtaining a current flowing through the inductor;
Load estimation means for estimating the capacitive load value using the current value obtained by the current value acquisition means and the differential value of the output voltage;
Load adaptive control comprising: parameter switching means for switching an internal control parameter so as not to cause a bump in the output when the capacitive load fluctuates in accordance with a load value estimated by the load estimating means. apparatus. A load that receives an input signal, supplies an inductive load connected to the output terminal to an output voltage or current corresponding to the input signal, has an inductor connected to the output terminal, and the inductive load fluctuates during operation In an adaptive controller,
Current value obtaining means for obtaining a current flowing through the inductor;
Load estimation means for estimating the inductive load value using a differential value of the current obtained by the current value acquisition means and a voltage across a series circuit of the inductor and the inductive load;
Load adaptive control comprising: parameter switching means for switching an internal control parameter so that no bump is generated in the output when the inductive load fluctuates according to the load value estimated by the load estimation means. apparatus. In response to an input signal, an output voltage or current corresponding to the input signal is supplied to a resistive load connected to the output terminal, and an inductor and a capacitor are connected inside the output terminal, and the resistive load fluctuates during operation. In the load adaptive control device,
Current value obtaining means for obtaining a current flowing through the inductor;
Load estimation means for estimating the resistive load value using the current value obtained by the current value acquisition means and the differential value of the output voltage;
A load adaptive control apparatus, comprising: parameter switching means for switching an internal control parameter so that a bump does not occur when the resistive load changes according to a load value estimated by the load estimating means. A load that receives an input signal and supplies an output voltage or current corresponding to the input signal to a resistive load connected to the output terminal, and an inductor is connected inside the output terminal, and the resistive load fluctuates during operation In an adaptive controller,
Current value obtaining means for obtaining a current flowing through the inductor;
Load estimation means for estimating the resistive load value using a differential value of the current obtained by the current value acquisition means and a voltage across a series circuit of the inductor and the resistive load;
A load adaptive control apparatus, comprising: parameter switching means for switching an internal control parameter so that a bump does not occur when the resistive load changes according to a load value estimated by the load estimating means.

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