JP6981687B2 - Load power factor control method using matrix converter for induction melting furnace - Google Patents
Load power factor control method using matrix converter for induction melting furnace Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D11/00—Arrangement of elements for electric heating in or on furnaces
- F27D11/06—Induction heating, i.e. in which the material being heated, or its container or elements embodied therein, form the secondary of a transformer
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0009—Devices or circuits for detecting current in a converter
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0064—Magnetic structures combining different functions, e.g. storage, filtering or transformation
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
- H02M1/4208—Arrangements for improving power factor of AC input
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/01—Resonant DC/DC converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
- H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
- H02M5/22—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M5/275—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M5/293—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M5/2932—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage, current or power
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
- H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
- H02M5/22—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M5/275—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M5/297—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal for conversion of frequency
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Ac-Ac Conversion (AREA)
- General Induction Heating (AREA)
Description
本発明は、誘導溶解炉用マトリックスコンバータを用いた負荷力率制御方法に関する。 The present invention relates to a load power factor control method using a matrix converter for an induction melting furnace.
誘導加熱装置は，ガス炉や電気炉などの従来の加熱装置と比べ，安全安心で高効率，クリーンな加熱が可能であり，近年需要が高まっている。
誘導加熱は、コイルに高周波電流を流すことで、電磁誘導の法則によって負荷となる金属に誘導電流を流し、
誘導電流と金属の内部抵抗でジュール熱を発生させて金属を直接加熱する方法である。
このような従来の誘導溶解炉の制御においては、
負荷力率を常に１に近づけるよう制御を行う力率制御が重要であることが知られている。
例えば特許文献１には、
被溶解材を溶解させる第１段階において、力率検出部を介して検出される出力力率が１となる周波数の制御信号を生成し、
溶解した被溶解材に成分調整材を添加する第２段階において、成分調整材を被溶解材に溶け込ませるのに適した周波数の制御信号を生成し、
成分調整材を被溶解材に溶け込んだ後の第３段階において、力率検出部を介して検出される出力力率が１となる周波数の制御信号を生成することを特徴とする誘導溶解炉について記載されている。
Compared with conventional heating devices such as gas furnaces and electric furnaces, induction heating devices are safe, secure, highly efficient, and can perform clean heating, and demand is increasing in recent years.
Induction heating involves passing a high-frequency current through the coil, causing the induced current to flow through the metal that is the load according to the law of electromagnetic induction.
This is a method of directly heating a metal by generating Joule heat with an induced current and the internal resistance of the metal.
In the control of such a conventional induction melting furnace,
It is known that power factor control, which controls the load power factor so as to always approach 1, is important.
For example, in
In the first step of melting the material to be dissolved, a control signal having a frequency at which the output power factor detected via the power factor detection unit is 1 is generated.
In the second step of adding the component adjusting material to the dissolved material, a control signal having a frequency suitable for dissolving the component adjusting material in the dissolved material is generated.
About an induction melting furnace characterized by generating a control signal of a frequency at which the output power factor detected through the power factor detection unit becomes 1 in the third stage after the component adjusting material is melted into the material to be melted. Has been described.
しかしながら、上記従来の誘導溶解炉の制御方法では、以下のような課題がある。
たとえば、誘導溶解炉に用いる誘導加熱コイルは被溶解材の加熱中にインダクタンス変化が生じる。
それにより，出力電圧と電流との力率角が変化し，効率低下，電力変化，ハードスイッチングによるスイッチングロスの増加などの問題が発生する。
すなわち、従来のマトリックスコンバータでは，負荷力率は一定として制御しているが，誘導加熱装置では，負荷のコイルのインダクタンスが稼働中に変化するため（被溶解材の温度上昇により），負荷力率は変化する。
ここで，ソフトスイッチングの電流条件を満たすには，マトリックスコンバータの出力電流ｉｏｕｔは正弦波であるため，出力電流ｉｏｕｔは，出力電圧ｖｏｕｔに対して，ある程度遅れ，つまり，力率角Δφは正のある一定の値以上である必要があった。
また，負荷力率が１から遠ざかるほど，負荷の効率は悪くなる。
そのため，ソフトスイッチング可能で，効率が最大になる最適の負荷力率角に保つことが望ましかった。
本発明は，上記の課題を解決することを目的とし、誘導加熱炉コイルの負荷インダクタンス変化に対して，出力周波数調整により，負荷力率を指令通りに制御する方法を提案するものである。
However, the conventional control method for the induction melting furnace has the following problems.
For example, in an induction heating coil used in an induction melting furnace, an inductance change occurs during heating of the material to be melted.
As a result, the power factor angle between the output voltage and the current changes, causing problems such as a decrease in efficiency, a change in power, and an increase in switching loss due to hard switching.
That is, in the conventional matrix converter, the load power factor is controlled as constant, but in the induction heating device, the inductance of the coil of the load changes during operation (due to the temperature rise of the material to be dissolved), so the load power factor Changes.
Here, in order to satisfy the current condition of soft switching, since the output current iout of the matrix converter is a sine wave, the output current iout lags the output voltage vout to some extent, that is, the power factor angle Δφ is positive. It had to be above a certain value.
Further, the farther the load power factor is from 1, the worse the load efficiency becomes.
Therefore, it was desirable to maintain the optimum load power factor angle that enables soft switching and maximizes efficiency.
An object of the present invention is to solve the above-mentioned problems, and to propose a method of controlling a load power factor as instructed by adjusting an output frequency with respect to a change in load inductance of an induction heating furnace coil.
本発明は以下の特徴を有する。
（１）誘導溶解炉用マトリックスコンバータを用いた負荷力率制御方法において、
力率角Δφが力率角指令値Δφ＊に対して遅れの場合は、
マトリックスコンバータの出力周波数ｆｒを小さくして、
力率角Δφを力率角指令値Δφ＊に追従させ、
力率角Δφが力率角指令値Δφ＊に対して進みの場合は、
マトリックスコンバータの出力周波数ｆｒを大きくして、
力率角Δφを力率角指令値Δφ＊に追従させるようにした誘導溶解炉用マトリックスコンバータを用いた負荷力率制御方法であって、
前記力率角Δφは、
前記出力周波数ｆｒの電圧位相を基準として、電流波形でのθに対して、
０≦θ＜πの半周期における０からの距離と、
π≦θ＜２πの半周期におけるπからの距離とが、
同じである位置を検出ポイントとすることを特徴とする。
The present invention has the following features.
(1) In the load power factor control method using the matrix converter for the induction melting furnace
If the power factor angle Δφ lags behind the power factor angle command value Δφ *,
Decrease the output frequency fr of the matrix converter to reduce it.
Make the power factor angle Δφ follow the power factor angle command value Δφ *,
If the power factor angle Δφ advances with respect to the power factor angle command value Δφ *,
Increase the output frequency fr of the matrix converter
It is a load power factor control method using a matrix converter for an induction melting furnace in which the power factor angle Δφ follows the power factor angle command value Δφ *.
The power factor angle Δφ is
With respect to θ in the current waveform with reference to the voltage phase of the output frequency fr.
The distance from 0 in a half cycle of 0 ≤ θ <π,
The distance from π in the half cycle of π ≤ θ <2π is
The detection point is the same position.
本発明の誘導溶解炉用マトリックスコンバータを用いた負荷力率制御方法は、誘導加熱炉のコイルの負荷インダクタンス変化に対して，出力周波数調整により，負荷力率を指令通りに制御することができる。
すなわち、誘導加熱装置の負荷力率制御をすることで，任意の力率角に追従させることができる。
また，マトリックスコンバータを使用することで，三相交流を、直接，高周波交流に変換できるので，装置の小型化や高効率化を実現できる。
In the load power factor control method using the matrix converter for an induction heating furnace of the present invention, the load power factor can be controlled as instructed by adjusting the output frequency with respect to the change in the load inductance of the coil of the induction heating furnace.
That is, by controlling the load power factor of the induction heating device, it is possible to follow an arbitrary power factor angle.
In addition, by using a matrix converter, three-phase alternating current can be directly converted to high-frequency alternating current, so that the equipment can be made smaller and more efficient.
以下、図面を用いて、本実施形態の誘導溶解炉用マトリックスコンバータを用いた負荷力率制御方法について説明する。 Hereinafter, the load power factor control method using the matrix converter for the induction melting furnace of the present embodiment will be described with reference to the drawings.
図１に、本発明の誘導溶解炉用マトリックスコンバータの負荷力率制御装置の主回路構成を示す。
図１に示すように、本発明の誘導溶解炉用マトリックスコンバータの負荷力率制御装置は、
三相交流電源（ｅｓｕ、ｅｓｖ、ｅｓｗ）、ＬＣフィルタ（Ｌｆ、Ｃｆ）、マトリックスコンバータ（ＭＣ）、高周波トランス（Ｔ１，Ｔ２）、誘導加熱炉（Ｒｗ，Ｌｗ）、共振コンデンサ（Ｃ）によって構成される。
図１において、整合トランス（Ｔ１）の一次側を電源側（Power Supply side），二次側を負荷側（Load side）と呼び、
三相交流電源（ｅｓｕ、ｅｓｖ、ｅｓｗ）は，電源に流れる電流の高調波成分を抑制するためにＬｆとＣｆからなるＬＣフィルタを通してマトリックスコンバータ（ＭＣ）に接続されている。
負荷側は，カレントトランス（Ｔ２）を介して共振コンデンサ（Ｃ）と負荷インダクタンス（Ｌｗ）が直列に接続されており，ＬＣ共振するようになっている。
FIG. 1 shows the main circuit configuration of the load power factor control device of the matrix converter for an induction melting furnace of the present invention.
As shown in FIG. 1, the load power factor control device for the matrix converter for an induction melting furnace of the present invention is
Consists of three-phase AC power supply (esu, esv, sw), LC filter (Lf, Cf), matrix converter (MC), high frequency transformer (T1, T2), induction heating furnace (Rw, Lw), resonance capacitor (C) Will be done.
In FIG. 1, the primary side of the matching transformer (T1) is referred to as a power supply side, and the secondary side is referred to as a load side.
A three-phase AC power supply (esu, esv, esw) is connected to a matrix converter (MC) through an LC filter composed of Lf and Cf in order to suppress a harmonic component of a current flowing through the power supply.
On the load side, a resonance capacitor (C) and a load inductance (Lw) are connected in series via a current transformer (T2) so that LC resonance occurs.
また、力率角の検出は以下のようにして行う。
すなわち、マトリックスコンバータ（ＭＣ）の出力電圧（ｖｏｕｔ），出力電流（ｉｏｕｔ）を，実効値（Ｖｏｕｔ，Ｉｏｕｔ）の正弦波で近似し，次式で与えられる。
The power factor angle is detected as follows.
That is, the output voltage (vout) and output current (iout) of the matrix converter (MC) are approximated by a sine wave of the effective value (Vout, Iout) and given by the following equation.
式（１）
前記式（１）、（２）、（３）を用いて、出力周波数ｆｒの半周期ごとに力率角Δφを検出する。
すなわち、力率角Δφの検出は、例えば、後述する電流検出回路（図３参照）を用いて、
０＜θ＜πの半周期において，θ＝π／４、３π／４の出力電流ｉｏｕｔ（π／４）、ｉｏｕｔ（３π／４）を検出し，（２）式に代入して，次式（４）乃至（７）で、力率角Δφ，出力電流実効値Ｉｏｕｔを得る。
Using the above equations (1), (2), and (3), the power factor angle Δφ is detected every half cycle of the output frequency fr.
That is, the power factor angle Δφ can be detected by using, for example, a current detection circuit (see FIG. 3) described later.
In the half cycle of 0 <θ <π, the output currents iout (π / 4) and iout (3π / 4) of θ = π / 4, 3π / 4 are detected and substituted into equation (2), and the following equation is used. In (4) to (7), the power factor angle Δφ and the output current effective value Iout are obtained.
式（４）
次に、本発明における力率制御について説明する。
すなわち、本発明の誘導溶解炉用マトリックスコンバータを用いた負荷力率制御方法においては、溶解する金属を加熱する途中で、負荷インダクタンスＬｗの変化に対応させる。
負荷インダクタンスＬｗの変化に伴い力率角Δφも変化するため，マトリックスコンバータ（ＭＣ）の出力周波数ｆｒを調整し，力率角Δφを制御するようにしている。
Next, the power factor control in the present invention will be described.
That is, in the load power factor control method using the matrix converter for an induction melting furnace of the present invention, the load inductance Lw is changed in the middle of heating the metal to be melted.
Since the power factor angle Δφ also changes as the load inductance Lw changes, the output frequency fr of the matrix converter (MC) is adjusted to control the power factor angle Δφ.
また、本発明においては、負荷側に直列に接続されている負荷インダクタンスＬｗの温度による変化があるので，力率角Δφを下記のように調整する。
すなわち、図１に示す回路において，負荷側（整合トランス（Ｔ１）の二次側）は、カレントトランス（Ｔ２）を介してＲＬＣ直列回路となっているため，整合トランス（Ｔ１）及びカレントトランス（Ｔ２）の巻数比をそれぞれｎ１，ｎ２とすると、マトリックスコンバータ（ＭＣ）の出力電圧（ｖｏｕｔ）と出力電流（ｉｏｕｔ）の関係式，位相差（力率角Δφ）は、それぞれ式（９）、（１０）で表すことができる。
Further, in the present invention, since the load inductance Lw connected in series with the load side changes depending on the temperature, the power factor angle Δφ is adjusted as follows.
That is, in the circuit shown in FIG. 1, since the load side (secondary side of the matching transformer (T1)) is an RLC series circuit via the current transformer (T2), the matching transformer (T1) and the current transformer ( Assuming that the turns ratio of T2) is n1 and n2, respectively, the relational expression between the output voltage (vout) and the output current (iout) of the matrix converter (MC) and the phase difference (power factor angle Δφ) are expressed in equations (9) and φ, respectively. It can be represented by (10).
式（９）
図２は，ＲＬＣ直列回路ベクトル図であり、式（９）（１０）のベクトル図を示す。
力率角指令値Δφ＊に対して，力率角Δφが，図２（ａ）では遅れ，図２（ｂ）では進みの場合を示している。
本発明では、力率角誤差Δφ＊−Δφに対してＰＩ制御演算をし，マトリックスコンバータ（ＭＣ）の出力周波数ｆｒにフィードバックして、力率角Δφを制御するようにしている。詳しくは後述する。
FIG. 2 is a vector diagram of the RLC series circuit, and shows the vector diagram of the equations (9) and (10).
FIG. 2A shows a case where the power factor angle Δφ is delayed and FIG. 2B shows a case where the power factor angle Δφ is advanced with respect to the power factor angle command value Δφ *.
In the present invention, the PI control calculation is performed for the power factor angle error Δφ * −Δφ and fed back to the output frequency fr of the matrix converter (MC) to control the power factor angle Δφ. Details will be described later.
次に、実施形態で用いた電流検出回路を図３に示す。
図３に示すホールＣＴ型電流センサ（レムジャパン株式会社製，ＬＡ５５−Ｐ）を、図１に示すマトリックスコンバータ（ＭＣ）の出力電流（ｉｏｕｔ）に取付け、測定抵抗により電圧に変換し，ボルテージフォロアを通ったアナログ量をＳＭＢ同軸コネクタを通してＦＰＧＡボード（Ｘｉｌｉｎｘ社のＸＣ６ＳＬＸ４５−２ＦＧＧ６７６Ｃを使用）に入力する。
電流センサの巻き数比は１：１０００で，実施形態では，ホールＣＴに一回電流が通るように配線している。
そのため，電流の最大入力電流ｉｏｕｔｍａｘは、式（１１）で示される。
Next, the current detection circuit used in the embodiment is shown in FIG.
The Hall CT type current sensor (LA55-P manufactured by REM Japan Co., Ltd.) shown in FIG. 3 is attached to the output current (iout) of the matrix converter (MC) shown in FIG. 1, converted into a voltage by a measurement resistance, and voltage follower. The amount of analog passed through is input to the FPGA board (using XC6SLX45-2FGG676C manufactured by Xilinx) through the SMB coaxial connector.
The turns ratio of the current sensor is 1: 1000, and in the embodiment, wiring is performed so that the current passes through the Hall CT once.
Therefore, the maximum input current ioutmax of the current is represented by the equation (11).
式（１１）
図３に示す電流検出回路において、マトリックスコンバータ（ＭＣ）の出力電流（ｉｏｕｔ）を検出し，以下のようにして力率角Δφを算出するのであるが、まずは、マトリックスコンバータ（ＭＣ）の出力周波数（ｆｒ）の半周期ごとに力率角Δφを算出する。
この場合、マトリックスコンバータの出力電流（ｉｏｕｔ）を，実効値（Ｉｏｕｔ）の正弦波で近似し，次式（１２）、（１３）で与える。
これらの式において，電流は電圧に対してΔφ遅れとする。
In the current detection circuit shown in FIG. 3, the output current (iout) of the matrix converter (MC) is detected and the power factor angle Δφ is calculated as follows. First, the output frequency of the matrix converter (MC) is calculated. The power factor angle Δφ is calculated every half cycle of (fr).
In this case, the output current (iout) of the matrix converter is approximated by a sine wave of the effective value (Iout), and is given by the following equations (12) and (13).
In these equations, the current lags the voltage by Δφ.
式（１２）
図４に出力電圧（ｖｏｕｔ）と出力電流（ｉｏｕｔ）の波形を示す。
図４に示すように、０≦θ＜πの半周期において、
θ＝π／４の出力電流（ｉｏｕｔ（π／４））、
θ＝３π／４の出力電流（ｉｏｕｔ（３π／４））を検出し，
出力電流（ｉｏｕｔ）の式に代入すると式（１４）を得る。
FIG. 4 shows the waveforms of the output voltage (vout) and the output current (iout).
As shown in FIG. 4, in a half cycle of 0 ≦ θ <π,
Output current of θ = π / 4 (iout (π / 4)),
Detects the output current (iout (3π / 4)) of θ = 3π / 4 and detects it.
Substituting into the equation of output current (iout) gives equation (14).
式（１４）
式（１５）
次の、π≦θ＜２πの半周期においても，
ｉｏｕｔ（５π／４）＝−ｉｏｕｔ（π／４）、
ｉｏｕｔ（７π／４）＝−ｉｏｕｔ（３π／４）となり、
力率角Δφ、出力電流実効値（Ｉｏｕｔ）は同様の結果を得ることができる。
ここで，出力電流実効値（Ｉｏｕｔ）は大電流が流れた時の制御停止に用いる。
In the next half cycle of π≤θ <2π,
iout (5π / 4) = −iout (π / 4),
iout (7π / 4) = −iout (3π / 4)
Similar results can be obtained for the power factor angle Δφ and the output current effective value (Iout).
Here, the output current effective value (Iout) is used to stop the control when a large current flows.
なお、実施形態では，計算の簡単化のためにθ＝π／４、３π／４を用いているが、
図４の説明から分かるように，０，πからの距離が同じであれば、θ＝π／４、３π／４でなくとも良い。
すなわち、検出ポイントをπ／４、３π／４に決める必要はなく、電圧位相を基準として、電流波形でのθに対して、「０＋α」、「π−α」の点が同じ値であれば位相差が０となり、力率は１となるので、電流波形でのθに対して、「０＋α」、「π−α」の点での電流を検出すればよい。
In the embodiment, θ = π / 4, 3π / 4 is used for simplification of calculation.
As can be seen from the explanation of FIG. 4, if the distances from 0 and π are the same, θ = π / 4, 3π / 4 does not have to be.
That is, it is not necessary to determine the detection points to π / 4, 3π / 4, and if the points of "0 + α" and "π-α" are the same value with respect to θ in the current waveform with respect to the voltage phase. Since the phase difference becomes 0 and the power factor becomes 1, the currents at the points “0 + α” and “π−α” may be detected with respect to θ in the current waveform.
図５は，
式（１５）、式（１６）の出力電流（ｉｏｕｔ）の波形である。
図５を参照して、直流成分ΔＩｏｕｔの算出方法を以下に示す。
図５において、出力電圧（ｖｏｕｔ）が正半周期０≦θ＜πと負の半周期π≦θ＜２πにおけるＩ＋（図４参照）をそれぞれＩ＋＋、Ｉ＋−とおくと，
直流成分ΔＩｏｕｔによって図５に示すように｜Ｉ＋＋｜≠｜Ｉ＋−｜となる。
Ｉ＋＋とＩ＋−の絶対値の差をΔＩ＋とおくと，次式（１７）で表される。
FIG. 5 shows
It is a waveform of the output current (iout) of the formula (15) and the formula (16).
With reference to FIG. 5, the calculation method of the DC component ΔIout is shown below.
In FIG. 5, if I + (see FIG. 4) in which the output voltage (vout) has a positive half cycle of 0 ≦ θ <π and a negative half cycle of π ≦ θ <2π is I ++ and I + −, respectively,
As shown in FIG. 5, the DC component ΔIout becomes | I ++ | ≠ | I + − |.
If the difference between the absolute values of I ++ and I ++ is ΔI +, it is expressed by the following equation (17).
式（１７）
となるように制御すればよいことがわかる。
Equation (17)
It can be seen that it should be controlled so as to be.
また，出力電流ｉｏｕｔに直流成分ΔＩｏｕｔが乗ったとき，出力電流ｉｏｕｔを次式（１８）で表わされる。 Further, when the DC component ΔIout is added to the output current iout, the output current iout is expressed by the following equation (18).
式（１８）
式（１８−１）
次に、変化した力率角は、力率角誤差に対してＰＩ制御演算をして出力周波数にフィードバックして制御するのであるが、具体的な手段について以下に説明する。
図２は、マトリックスコンバータの出力電圧（ｖｏｕｔ）と出力電流（ｉｏｕｔ）の関係を示したベクトル図である。
図２（ａ）は、力率角指令値Δφ＊に対して、力率角Δφが遅れの場合を示し，図２（ｂ）は、力率角Δφが進みの場合をそれぞれ示す。
Next, the changed power factor angle is controlled by performing a PI control calculation for the power factor angle error and feeding it back to the output frequency. Specific means will be described below.
FIG. 2 is a vector diagram showing the relationship between the output voltage (vout) and the output current (iout) of the matrix converter.
FIG. 2A shows a case where the power factor angle Δφ is delayed with respect to the power factor angle command value Δφ *, and FIG. 2B shows a case where the power factor angle Δφ is advanced.
なお，図２に示すＡは次式（１９）で与えられる。
式（１９）
Equation (19)
図２（ａ）に示すように，力率角Δφが大きくなり，力率角指令値Δφ＊に対して遅れた時は，マトリックスコンバータの出力角周波数ｆｒを小さくする。
これにより、出力電流（ｉｏｕｔ）のインダクタンス成分は小さく，キャパシタ成分は大きくなり，力率角Δφは小さくなり，出力電流（ｉｏｕｔ）は進む。
すなわち，力率角Δφが力率角指令値Δφ＊に対して遅れの場合は，マトリックスコンバータ（ＭＣ）の出力周波数ｆｒを小さくすることで，力率角Δφを力率角指令値Δφ＊に追従させることができる。
As shown in FIG. 2A, when the power factor angle Δφ becomes large and is delayed with respect to the power factor angle command value Δφ *, the output angular frequency fr of the matrix converter is reduced.
As a result, the inductance component of the output current (iout) is small, the capacitor component is large, the power factor angle Δφ is small, and the output current (iout) is advanced.
That is, when the power factor angle Δφ lags behind the power factor angle command value Δφ *, the power factor angle Δφ is changed to the power factor angle command value Δφ * by reducing the output frequency fr of the matrix converter (MC). It can be made to follow.
図２（ｂ）に示すように，力率角Δφが小さくなり，力率角指令値Δφ＊に対して進みの時は，マトリックスコンバータの出力角周波数ｆｒを大きくする。
これにより、出力電流（ｉｏｕｔ）のインダクタンス成分は大きく，キャパシタ成分は小さくなり，出力電流（ｉｏｕｔ）は遅れる。
すなわち，力率角Δφが力率角指令値Δφ＊に対して進みの場合は，マトリックスコンバータ（ＭＣ）の出力周波数ｆｒを大きくすることで，力率角Δφは力率角指令値Δφ＊に追従させることができるのである。
As shown in FIG. 2B, when the power factor angle Δφ becomes smaller and advances with respect to the power factor angle command value Δφ *, the output angular frequency fr of the matrix converter is increased.
As a result, the inductance component of the output current (iout) is large, the capacitor component is small, and the output current (iout) is delayed.
That is, when the power factor angle Δφ advances with respect to the power factor angle command value Δφ *, the power factor angle Δφ becomes the power factor angle command value Δφ * by increasing the output frequency fr of the matrix converter (MC). It can be made to follow.
次に、図３に示す電流検出回路を用いて、マトリックスコンバータの出力電流（ｉｏｕｔ）を検出して，力率角Δφを算出し，ローパスフィルタ（ＬＰＦ）を通過させた値ΔφＬと力率角指令値Δφ＊との偏差ｄΔφを次式（２０）により求める。 Next, using the current detection circuit shown in FIG. 3, the output current (iout) of the matrix converter is detected, the power factor angle Δφ is calculated, and the value ΔφL and the power factor angle passed through the low-pass filter (LPF) are calculated. The deviation dΔφ from the command value Δφ * is obtained by the following equation (20).
式（２０）
式（２０）で求めた偏差ｄΔφに対して次式（２１）のＰＩ制御を行い，マトリックスコンバータ（ＭＣ）の出力周波数ｆｒの補正項Δｆｒを求める。 The PI control of the following equation (21) is performed on the deviation dΔφ obtained by the equation (20), and the correction term Δfr of the output frequency fr of the matrix converter (MC) is obtained.
式（２１）
ここで、ＫＰ、ＫＩはそれぞれ，制御系の比例ゲインと積分ゲインである。
式（２１）と任意の初期出力周波数ｆｒを足し合わせたものをマトリックスコンバータ（ＭＣ）の出力周波数指令値ｆｒ＊とし，次式（２２）で表す。
Here, KP and KI are the proportional gain and the integral gain of the control system, respectively.
The sum of the equation (21) and an arbitrary initial output frequency fr is defined as the output frequency command value fr * of the matrix converter (MC), and is expressed by the following equation (22).
式（２２）
次に、本発明の実施例について説明する。
表１に，実施例において用いた条件を示す。
実施例においては、マトリックスコンバータの出力側をＲＬＣ直列回路として行った。
出力周波数ｆｒ＝１１ｋＨｚの一定値を与え，その後，力率制御を開始した。
Next, examples of the present invention will be described.
Table 1 shows the conditions used in the examples.
In the embodiment, the output side of the matrix converter was used as an RLC series circuit.
A constant value of output frequency fr = 11 kHz was given, and then power factor control was started.
＜実施例の評価＞
実施例の評価を図６乃至図８に示す。
図６には、上から、それぞれ，力率制御をしているときの定常状態における一相分の電源電圧ｅｓｕ，電源電流ｉｓｕ，マトリックスコンバータの出力電圧ｖｏｕｔ，出力電流ｉｏｕｔの電源二周期分の波形を示す。
電源電流ｉｓｕは正弦波状になり，ＴＨＤは６．４０％であった。
図７は，（ａ）力率制御前、（ｂ）制御後の波形を示し、マトリックスコンバータの出力電圧ｖｏｕｔ，出力電流ｉｏｕｔの一周期分の波形である。
図８（ａ）は，出力周波数ｆｒ＝１１ｋＨｚの一定値を与えたときの波形である。
力率角Δφ＝０．１２ｒａｄとなり，遅れ電流である。
図８（ｂ）は，力率角指令値Δφ＊＝０として制御した時の定常状態の波形であり，電流波形ｉｏｕｔにおいては，検出点電流，及び，近似正弦波も示している。
力率１の電流波形に制御されている。
図８は，出力周波数ｆｒと位相差Δφの，制御開始時の制御特性を示す。
約７５ｓで，ｆｒ＝１０．３６ｋＨｚ，Δφ＝０ｒａｄにそれぞれ収束している。
このとき，誘導加熱装置のインダクタンス変化は急激なものではないため，オーバーシュートしないよう十分な収束時間を与えた。
<Evaluation of Examples>
The evaluation of the examples is shown in FIGS. 6 to 8.
In FIG. 6, from the top, the power supply voltage su, the power supply current isu, the output voltage vout of the matrix converter, and the power supply cycle of the output current iout in the steady state when the power factor is controlled are shown. The waveform is shown.
The power supply current isu was sinusoidal and the THD was 6.40%.
FIG. 7 shows waveforms (a) before power factor control and (b) after control, and are waveforms for one cycle of the output voltage vout and the output current iout of the matrix converter.
FIG. 8A is a waveform when a constant value of output frequency fr = 11 kHz is given.
The power factor angle Δφ = 0.12 rad, which is a delayed current.
FIG. 8B is a steady-state waveform when controlled with the power factor angle command value Δφ * = 0, and the current waveform iout also shows the detection point current and the approximate sine wave.
It is controlled by a current waveform with a power factor of 1.
FIG. 8 shows the control characteristics of the output frequency fr and the phase difference Δφ at the start of control.
In about 75s, it converges to fr = 10.36kHz and Δφ = 0rad, respectively.
At this time, since the change in the inductance of the induction heating device was not abrupt, a sufficient convergence time was given so as not to overshoot.
本発明の誘導溶解炉用マトリックスコンバータを用いた負荷力率制御方法は、誘導加熱炉のコイルの負荷インダクタンス変化に対して，出力周波数調整により，負荷力率を指令通りに制御する方法であるので、広く誘導溶解炉に適用でき、産業上の利用可能性が高い。 The load power factor control method using the matrix converter for an induction heating furnace of the present invention is a method of controlling the load power factor as instructed by adjusting the output frequency with respect to the load inductance change of the coil of the induction heating furnace. , Can be widely applied to induction melting furnaces and has high industrial applicability.
Δφ 力率角
Δφ＊ 力率角指令値
ｆｒ マトリックスコンバータの出力周波数
ｆｒ＊ マトリックスコンバータの出力周波数指令値
ｅｓｕ、ｅｓｖ、ｅｓｗ 三相交流電源
Ｌｆ、Ｃｆ ＬＣフィルタ
ＭＣ マトリックスコンバータ
Ｔ１ 高周波トランス、整合トランス
Ｔ２ 高周波トランス、カレントトランス
Ｌｗ 誘導加熱炉の負荷インダクタンス
Ｒｗ 誘導加熱炉の負荷抵抗
Ｃ 共振コンデンサ
ｖｏｕｔ マトリックスコンバータの出力電圧
ｉｏｕｔ マトリックスコンバータの出力電流
Ｖｏｕｔ，Ｉｏｕｔ 実効値
Δφ＊−Δφ 力率角誤差
ｉｏｕｔｍａｘ 最大入力電流式
ΔＩｏｕｔ 直流成分
Δφ Power factor angle Δφ * Power factor angle command value fr Matrix converter output frequency fr * Matrix converter output frequency command value esu, esv, esw Three-phase AC power supply Lf, Cf LC filter MC Matrix converter T1 High frequency transformer, Matching transformer T2 High frequency transformer, current transformer Lw Load inductance of induction heating furnace Rw Load resistance of induction heating furnace C Resonant capacitor vout Output voltage of matrix converter iout Output current of matrix converter Vout, Iout Effective value Δφ * −Δφ Power factor angle error ioutmax Maximum input Current type ΔIout DC component
Claims (1)
力率角Δφが力率角指令値Δφ＊に対して遅れの場合は、
マトリックスコンバータの出力周波数ｆｒを小さくして、
力率角Δφを力率角指令値Δφ＊に追従させ、
力率角Δφが力率角指令値Δφ＊に対して進みの場合は、
マトリックスコンバータの出力周波数ｆｒを大きくして、
力率角Δφを力率角指令値Δφ＊に追従させるようにした誘導溶解炉用マトリックスコンバータを用いた負荷力率制御方法であって、
前記力率角Δφは、
前記出力周波数ｆｒの電圧位相を基準として、電流波形でのθに対して、
０≦θ＜πの半周期における０からの距離と、
π≦θ＜２πの半周期におけるπからの距離とが、
同じである位置を検出ポイントとすることを
特徴とする誘導溶解炉用マトリックスコンバータを用いた負荷力率制御方法。
In the load power factor control method using a matrix converter for an induction melting furnace,
If the power factor angle Δφ lags behind the power factor angle command value Δφ *,
Decrease the output frequency fr of the matrix converter to reduce it.
Make the power factor angle Δφ follow the power factor angle command value Δφ *,
If the power factor angle Δφ advances with respect to the power factor angle command value Δφ *,
Increase the output frequency fr of the matrix converter
It is a load power factor control method using a matrix converter for an induction melting furnace in which the power factor angle Δφ follows the power factor angle command value Δφ *.
The power factor angle Δφ is
With respect to θ in the current waveform with reference to the voltage phase of the output frequency fr.
The distance from 0 in a half cycle of 0 ≤ θ <π,
The distance from π in the half cycle of π ≤ θ <2π is
To set the same position as the detection point
A load power factor control method using a matrix converter for an induction melting furnace.
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| JP2020033170A JP6981687B2 (en) | 2020-02-28 | 2020-02-28 | Load power factor control method using matrix converter for induction melting furnace |
| CH001005/2022A CH718588B1 (en) | 2020-02-28 | 2021-02-25 | Method for controlling a load power factor using a matrix converter for induction melting furnaces. |
| DE112021001320.3T DE112021001320T5 (en) | 2020-02-28 | 2021-02-25 | Method of controlling a load power factor using a matrix converter for induction melting furnaces |
| PCT/JP2021/007179 WO2021172460A1 (en) | 2020-02-28 | 2021-02-25 | Load power factor control method using matrix converter for induction melting furnace |
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| JP5656532B2 (en) * | 2010-09-28 | 2015-01-21 | 北芝電機株式会社 | Induction melting furnace |
| JP5079865B2 (en) * | 2010-12-07 | 2012-11-21 | 北芝電機株式会社 | Induction melting furnace |
| JP6355187B2 (en) * | 2014-02-07 | 2018-07-11 | 国立大学法人北海道大学 | Power converter |
| JP6562301B2 (en) * | 2015-08-26 | 2019-08-21 | 国立大学法人 名古屋工業大学 | Bidirectional switch circuit, power converter using the same, and control method thereof |
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