JP2007124762A - Current detecting circuit in voltage converter - Google Patents

Current detecting circuit in voltage converter Download PDF

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JP2007124762A
JP2007124762A JP2005311366A JP2005311366A JP2007124762A JP 2007124762 A JP2007124762 A JP 2007124762A JP 2005311366 A JP2005311366 A JP 2005311366A JP 2005311366 A JP2005311366 A JP 2005311366A JP 2007124762 A JP2007124762 A JP 2007124762A
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current
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circuit
voltage source
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JP4835107B2 (en
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Toshie Miura
敏栄 三浦
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Fuji Electric Co Ltd
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Fuji Electric Systems Co Ltd
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<P>PROBLEM TO BE SOLVED: To prevent a noise applied to a controller and an adverse effect on a control such as a malfunction in a current zero-cross detection due to a distortion in a detection of an output current if there is a capacitive component such as a stray capacitance at an output of a voltage inverter impossible to control a waveform. <P>SOLUTION: A circuit comprising a reactor, a resistor and a capacitor is connected to the capacitive component in parallel, the current is detected and added to the detection of the output current from the voltage inverter, and the distortion in the waveform of the detected current is corrected in a current detecting method if there is the capacitive component at the output of the voltage inverter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、電圧形インバータ回路を用いた誘導加熱装置、高周波電源などの電流検出回路に関し、特に出力回路に負荷の他に浮遊容量が存在する場合の電流検出回路に関する。   The present invention relates to a current detection circuit such as an induction heating device using a voltage source inverter circuit or a high frequency power supply, and more particularly to a current detection circuit in the case where a stray capacitance is present in an output circuit in addition to a load.

図３に、従来技術を説明するための電流検出回路の構成図を、図４に図３の各部の波形図を示す。
ここで、例えば、数１０ｋＨｚ以上の高周波電源などにおいては、電源と負荷を接続する導体は表皮深さを考慮して薄い平板を用い、かつインダクタンスを低減するため、電流の往復する導体をラミネート配線することが多い。そのため、構造上浮遊静電容量が大きくなる。その他負荷回路に接続されることがある変圧器なども同様に、浮遊静電容量が大きい。また、電流検出用変流器３は電圧形インバータ出力の直近に配置され、この変流器３の出力が制御装置２に入力され、各種制御のための電流検出値となる。
以上より、主回路の等価回路は、図３に示すように電圧形インバータ１の出力に変流器３および容量成分４を介して負荷１０を接続する構成となる。 FIG. 3 shows a configuration diagram of a current detection circuit for explaining the prior art, and FIG. 4 shows a waveform diagram of each part of FIG.
Here, for example, in a high frequency power supply of several tens of kHz or more, the conductor connecting the power supply and the load uses a thin flat plate in consideration of the skin depth. Often to do. For this reason, the floating capacitance increases in structure. Similarly, a transformer that may be connected to a load circuit has a large floating capacitance. Further, the current detection current transformer 3 is disposed in the immediate vicinity of the voltage source inverter output, and the output of the current transformer 3 is input to the control device 2 and becomes a current detection value for various controls.
As described above, the equivalent circuit of the main circuit has a configuration in which the load 10 is connected to the output of the voltage source inverter 1 via the current transformer 3 and the capacitive component 4 as shown in FIG.

次に、図４を用いて、各部の波形について説明する。電圧形インバータ１の出力電圧Ｖｏは矩形波出力で、負荷１０は誘導成分と容量成分が直列に接続された直列共振負荷の場合である。ここで、制御装置２の電流検出に用いられる変流器３で検出される出力電流Ｉｏは、負荷電流ＩＬの波形（ここでは正弦波）が理想である。
しかし、前述のように容量成分４が存在するので、実際には、Ｖｏの電圧反転時に、容量成分４への充放電電流Ｉｃが流れ、ＩＬとＩｃを加算した歪み波形がＩｏとなる。
図５に、従来技術を説明するための電源装置の出力電流検出歪み補正方法の説明図を示す。特許文献１にその内容が記載されている。
図５において、電源装置１１から出力する電圧Ｖｏ、電流Ｉｏは正弦波が理想であるが、負荷１０の種類によってはＶｏ、Ｉｏが歪む場合がある。図５では、Ｉｏの歪みを補正する場合を示している。 Next, the waveform of each part will be described with reference to FIG. The output voltage Vo of the voltage source inverter 1 is a rectangular wave output, and the load 10 is a series resonant load in which an inductive component and a capacitive component are connected in series. Here, the output current Io detected by the current transformer 3 used for current detection of the control device 2 is ideally a waveform of the load current IL (here, a sine wave).
However, since the capacitive component 4 exists as described above, in actuality, when the voltage of Vo is reversed, the charge / discharge current Ic flows to the capacitive component 4, and the distortion waveform obtained by adding IL and Ic becomes Io.
FIG. 5 is an explanatory diagram of the output current detection distortion correction method of the power supply apparatus for explaining the conventional technique. Patent Document 1 describes the contents.
In FIG. 5, a sine wave is ideal for the voltage Vo and current Io output from the power supply device 11, but Vo and Io may be distorted depending on the type of the load 10. FIG. 5 shows a case where Io distortion is corrected.

変流器３で検出された電流Ｉｏは、制御装置２で正弦波の指令Ｉ＊から減算され、歪みを反転した成分となり、さらにＩ＊を加算し、結果として、正弦波の指令に歪み分を反転した成分を加算した値が得られる。これを電流指令とすることで、出力電流Ｉｏの歪みが除去される。
この場合の電源装置１１は、波形の制御が可能であるものに限られ、従来技術で示した、矩形波出力の電圧形インバータ１では、この方法で歪み補正を行うことは不可能である。
上述の他、配線長データと関数発生器を用いて出力電流検出値を補正する方法が特許文献２に開示されている。
特開２００４−１９４３８０号公報 特開平６−１６５５１６号公報 The current Io detected by the current transformer 3 is subtracted from the sine wave command I * by the control device 2 to become a component obtained by inverting the distortion. Further, I * is added, and as a result, the distortion component is added to the sine wave command. A value obtained by adding the components obtained by inverting is obtained. By using this as a current command, distortion of the output current Io is removed.
The power supply device 11 in this case is limited to one that can control the waveform, and the voltage-type inverter 1 having a rectangular wave output shown in the prior art cannot perform distortion correction by this method.
In addition to the above, Patent Document 2 discloses a method for correcting an output current detection value using wiring length data and a function generator.
JP 2004-194380 A JP-A-6-165516

本発明が解決しようとする課題は、電圧形インバータ、特に波形の制御が不可能な電圧形インバータの出力に浮遊静電容量などの容量成分が存在する場合に、出力電流の検出に歪みが生じることで、制御装置にノイズを重畳し、電流ゼロクロス検出の誤動作などの制御への悪影響を防止することである。   The problem to be solved by the present invention is that distortion occurs in the detection of the output current when there is a capacitance component such as stray capacitance at the output of the voltage source inverter, particularly the voltage source inverter whose waveform cannot be controlled. Thus, noise is superimposed on the control device to prevent adverse effects on the control such as malfunction of current zero cross detection.

本発明の課題を解決するための手段は、電圧形インバータ、特に波形の制御が不可能な電圧形インバータの出力に浮遊静電容量などの容量成分が存在する場合に、容量成分の直近または近傍の両端にコンデンサ、抵抗およびインダクタンスで構成された回路を接続し、前期回路に流れる電流を検出し、電圧形インバータの出力電流検出に加算することにより電流検出波形の歪みを補正することである。   Means for solving the problems of the present invention is that a voltage-type inverter, particularly a voltage-type inverter whose waveform cannot be controlled, has a capacitance component such as a floating capacitance at the output of the voltage-type inverter. Is connected to a circuit composed of a capacitor, a resistor, and an inductance, detects the current flowing in the previous circuit, and adds it to the output current detection of the voltage source inverter to correct the distortion of the current detection waveform.

本発明によれば、電圧形インバータ、特に波形の制御が不可能な電圧形インバータの出力に浮遊静電容量などの容量成分が存在する場合においても、出力電流検出波形に歪みが生じることが無いため、制御装置へ流入するノイズが低減でき、また電流ゼロクロス検出の誤動作などの制御への悪影響を無くすことができる。
これにより、ノイズ対策が不要となって、コストダウンが可能となり、また制御誤動作が無くなるため、装置の信頼性が向上する。 According to the present invention, the output current detection waveform is not distorted even when there is a capacitance component such as stray capacitance at the output of the voltage source inverter, particularly the voltage source inverter whose waveform cannot be controlled. Therefore, noise flowing into the control device can be reduced, and adverse effects on control such as malfunction of current zero cross detection can be eliminated.
This eliminates the need for noise countermeasures, enables cost reduction, and eliminates control malfunction, thereby improving the reliability of the apparatus.

本発明の要点は、電圧形インバータの出力に容量成分がある場合の電流検出方法として、容量成分と並列にリアクトル、抵抗およびコンデンサから構成された回路を接続し、この電流を検出し、これを電圧形インバータの出力電流検出に加算することにより、電流検出波形の歪みを補正することである。   The gist of the present invention is that a current detection method in the case where there is a capacitance component in the output of the voltage source inverter is connected to a circuit composed of a reactor, a resistor and a capacitor in parallel with the capacitance component, this current is detected, and this is detected. By adding to the output current detection of the voltage source inverter, the distortion of the current detection waveform is corrected.

図１に、本発明の第1実施例としての電流検出回路構成図を、図２に、図１の波形図を示す。
図３の従来技術と同様に、主回路の等価回路は、電圧形インバータ１の出力に容量成分４を介して負荷１０を接続する構成となる。容量成分４の両端にコンデンサ６、抵抗７およびインダクタンス８を直列に接続した補正回路５を並列接続し、同回路に流れる電流ＩＨを変流器９で検出し、変流器３で検出された電圧形インバータ１の出力電流Ｉｏに逆位相で加算する。
次に、図２を用いて、波形について説明する。図４の従来技術と同様に、電圧形インバータ１の出力電圧Ｖｏは矩形波出力で、負荷は誘導成分と容量成分が直列に接続された直列共振負荷の場合である。電圧形インバータ１の出力電流Ｉｏも、図４と同様に負荷電流ＩＬに容量成分４に流れる電流Ｉｃを加算した歪み波形となる。ここで、Ｉｃを補正回路５で模擬したＩＨをＩｏに逆位相で加算することで、ＩＬと同様のＩｏ＋（−ＩＨ）を得ることができ、歪みの無い波形を制御装置２の電流検出に用いることができる。 FIG. 1 shows a configuration diagram of a current detection circuit as a first embodiment of the present invention, and FIG. 2 shows a waveform diagram of FIG.
Similar to the prior art of FIG. 3, the equivalent circuit of the main circuit is configured to connect the load 10 to the output of the voltage source inverter 1 via the capacitive component 4. A correction circuit 5 in which a capacitor 6, a resistor 7 and an inductance 8 are connected in series at both ends of the capacitance component 4 is connected in parallel. A current IH flowing through the circuit is detected by a current transformer 9, and is detected by a current transformer 3. The output current Io of the voltage source inverter 1 is added in reverse phase.
Next, the waveform will be described with reference to FIG. As in the prior art of FIG. 4, the output voltage Vo of the voltage source inverter 1 is a rectangular wave output, and the load is a series resonant load in which an inductive component and a capacitive component are connected in series. The output current Io of the voltage source inverter 1 also has a distorted waveform obtained by adding the current Ic flowing through the capacitance component 4 to the load current IL as in FIG. Here, by adding IH simulated by the correction circuit 5 to Io in the opposite phase, Io + (− IH) similar to IL can be obtained, and a waveform without distortion is used for current detection of the control device 2. Can be used.

補正回路５のコンデンサ６は、容量成分４と比較して、例えば数十分の1の大きさで小さいため浮遊静電容量を増やすことは無い。ＩＨもＩｃの数十分の１の電流であり、Ｉｏを検出する変流器３の検出比とＩｃ／ＩＨの比×変流器９の検出比を等しくすることにより、ＩＨによるＩＣの模擬が可能となる。また、補正回路５はコンデンサ６のみで良い場合もあるが、浮遊静電容量は、各部に分布しており、例えば、負荷回路に接続されることがある変圧器の浮遊静電容量など、補正回路５の接続位置と離れた位置に存在している浮遊静電容量などに対しては、補正回路５の接続位置から見て、インダクタンスや抵抗を介して、浮遊静電容量が存在することになり、補正回路にも抵抗７やインダクタンス８を接続する必要がある。
ここで、電流検出には変流器３、９を用いているが、検出抵抗による電流検出方法など他の方法でも可能である。その他、ＩｏとＩＨの加算は、電流同士の加算でも電圧同士の加算でも可能である。 Since the capacitor 6 of the correction circuit 5 is smaller than the capacitance component 4 by, for example, a size of several tenths, the floating capacitance is not increased. IH is also a current of several tenths of Ic. By making the detection ratio of the current transformer 3 for detecting Io equal to the ratio of Ic / IH × the detection ratio of the current transformer 9, the IC simulation by IH is performed. Is possible. In some cases, the correction circuit 5 may be only the capacitor 6, but the stray capacitance is distributed in each part. For example, the stray capacitance of a transformer that may be connected to the load circuit is corrected. For stray capacitance that exists at a position distant from the connection position of the circuit 5, the stray capacitance exists through an inductance or a resistance as viewed from the connection position of the correction circuit 5. Therefore, it is necessary to connect the resistor 7 and the inductance 8 to the correction circuit.
Here, the current transformers 3 and 9 are used for current detection, but other methods such as a current detection method using a detection resistor are also possible. In addition, addition of Io and IH can be performed by addition of currents or addition of voltages.

尚、補正回路として、コンデンサ、抵抗およびインダクタンスの直列回路を用いた例を示したが、容量成分はその存在位置が出力回路の使用部品、配線構造などにより複雑であるため、補正回路としては必ずしも前記直列回路に限定されるものではない。   Although an example using a capacitor, resistor and inductance series circuit has been shown as the correction circuit, the position of the capacitance component is complicated depending on the parts used in the output circuit, the wiring structure, etc. It is not limited to the series circuit.

本発明は、誘導加熱装置、高周波インバータの他、負荷との配線長が長い電動機駆動用インバータなどへも適用可能である。   The present invention can be applied not only to an induction heating device and a high-frequency inverter but also to an inverter for driving a motor having a long wiring length with a load.

本発明の第1の実施例を示す電流検出回路の構成図1 is a configuration diagram of a current detection circuit showing a first embodiment of the present invention. 図1の動作波形図Operation waveform diagram of Fig. 1 従来の電流検出回路の構成図Configuration of conventional current detection circuit 図３の動作波形図Operation waveform diagram of FIG. 従来の電流波形歪み補正方法Conventional current waveform distortion correction method

符号の説明Explanation of symbols

１・・・電圧形インバータ ２・・・制御装置 ３、９・・・変流器
４・・・容量成分 ５・・・補正回路 ６・・・コンデンサ
７・・・抵抗 ８・・・インダクタンス １０・・・負荷
１１・・・電源装置 DESCRIPTION OF SYMBOLS 1 ... Voltage type inverter 2 ... Control apparatus 3, 9 ... Current transformer 4 ... Capacitance component 5 ... Correction circuit 6 ... Capacitor 7 ... Resistance 8 ... Inductance 10 ... Load 11 ... Power supply

Claims (2)

電圧形インバータの出力の電流を検出する電流検出回路において，
電圧形インバータの出力に存在する容量成分の直近または近傍の両端子間に，コンデンサ，抵抗およびインダクタンスを用いて構成された補正回路を接続し，前期補正回路に流れる電流を検出し，電圧形インバータ出力の電流検出に加算したことを特徴とする電圧形インバータの電流検出回路。 In the current detection circuit that detects the output current of the voltage source inverter,
Connect a correction circuit composed of capacitors, resistors, and inductances between the terminals near or near the capacitance component present in the output of the voltage source inverter, detect the current flowing in the correction circuit, and detect the current in the voltage source inverter A current detection circuit for a voltage source inverter, which is added to output current detection. 前記補正回路として、コンデンサ、抵抗およびインダクタンスの直列回路を用いたことを特徴とする電圧形インバータの電流検出回路。
A current detection circuit for a voltage source inverter, wherein a series circuit of a capacitor, a resistor and an inductance is used as the correction circuit.
JP2005311366A 2005-10-26 2005-10-26 Current detection circuit of voltage source converter Expired - Fee Related JP4835107B2 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03226274A (en) * 1990-01-31 1991-10-07 Okuma Mach Works Ltd Inverter unit
JPH06165516A (en) * 1992-11-13 1994-06-10 Fuji Electric Co Ltd Output current correction device of inverter
JPH07337024A (en) * 1994-06-06 1995-12-22 Toshiba Corp Inverter
JP2002095264A (en) * 2000-09-18 2002-03-29 Meidensha Corp Pwm inverter
JP2004194380A (en) * 2002-12-09 2004-07-08 Kansai Electric Power Co Inc:The Method for correcting distortion of ac voltage/current waveform

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03226274A (en) * 1990-01-31 1991-10-07 Okuma Mach Works Ltd Inverter unit
JPH06165516A (en) * 1992-11-13 1994-06-10 Fuji Electric Co Ltd Output current correction device of inverter
JPH07337024A (en) * 1994-06-06 1995-12-22 Toshiba Corp Inverter
JP2002095264A (en) * 2000-09-18 2002-03-29 Meidensha Corp Pwm inverter
JP2004194380A (en) * 2002-12-09 2004-07-08 Kansai Electric Power Co Inc:The Method for correcting distortion of ac voltage/current waveform

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