JP3186962B2 - NPC inverter device - Google Patents

NPC inverter device

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Publication number
JP3186962B2
JP3186962B2 JP32999095A JP32999095A JP3186962B2 JP 3186962 B2 JP3186962 B2 JP 3186962B2 JP 32999095 A JP32999095 A JP 32999095A JP 32999095 A JP32999095 A JP 32999095A JP 3186962 B2 JP3186962 B2 JP 3186962B2
Authority
JP
Japan
Prior art keywords
voltage
current
correction signal
npc inverter
current reference
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP32999095A
Other languages
Japanese (ja)
Other versions
JPH09172783A (en
Inventor
真司 多々良
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toshiba Corp
Original Assignee
Toshiba Corp
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Filing date
Publication date
Application filed by Toshiba Corp filed Critical Toshiba Corp
Priority to JP32999095A priority Critical patent/JP3186962B2/en
Priority to US08/766,476 priority patent/US5790396A/en
Priority to CA002193269A priority patent/CA2193269C/en
Priority to KR1019960067912A priority patent/KR100240905B1/en
Priority to CN96121324A priority patent/CN1055580C/en
Publication of JPH09172783A publication Critical patent/JPH09172783A/en
Application granted granted Critical
Publication of JP3186962B2 publication Critical patent/JP3186962B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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  • Inverter Devices (AREA)
  • Rectifiers (AREA)

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】本発明は、中性点を有する直
流電圧を交流電圧に変換するNPCインバータ装置に係
り、特に直流電圧を出力する直流電源のLC共振による
直流電圧の振動状態を抑制し、制御特性を改善したNP
Cインバータ装置に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an NPC inverter device for converting a DC voltage having a neutral point into an AC voltage, and more particularly to a DC power supply for outputting a DC voltage, which suppresses the oscillation state of the DC voltage due to LC resonance. , NP with improved control characteristics
It relates to a C inverter device.

【0002】[0002]

【従来の技術】中性点クランプ式インバータ(Neutral
Point Clamped Inverter) は、NPCインバータと呼称
され、中性点を有する直流電圧を高調波成分の少ない良
質の交流電力に変換するものとして知られており、この
種の従来のNPCインバータ装置を図4に示す。
2. Description of the Related Art Neutral point clamp type inverters (Neutral
Point Clamped Inverter) is called an NPC inverter, and is known to convert a DC voltage having a neutral point into high-quality AC power having less harmonic components. This type of conventional NPC inverter device is shown in FIG. Shown in

【0003】図4において、直流電源1は、交流電源1
a から正側の直流電圧Vdpを得るコンバータ1c と、交
流電源1b から負側の直流電圧Vdnを得るコンバータ1
d が直列接続され、リアクトル1e、1fとコンデンサ
2、3で成るLCフィルタを介してPN間に平滑され
た、中性点Cを有する直流電圧Vdpn (=Vdp+Vdn)
を出力する。この中性点Cを有する直流電圧Vdpn は、
NPCインバータ5により所望の交流電圧に変換され負
荷7に3相交流電流Iu,Iv,Iw として供給される。こ
の3相交流電流Iu,Iv,Iw は、変流器6でフィードバ
ック電流Iuf, Ivf, Iwfとして検出され、変換部(3
相2相変換)9で有効電流成分Iqfと無効電流成分Idf
の直交座標信号に変換される。この有効電流成分Iqf及
び無効電流成分Idfは電流制御器10で有効電流基準I
qr及び無効電流基準Idrとそれぞれ比較されそれぞれの
電流偏差を減少させるように有効電圧基準Eqrと無効電
圧基準Edrの直交座標信号が出力される。この直交座標
信号Eqr、Edrは変換部(2相3相変換)11で3相の
交流電圧基準Vu*, Vv*, Vw*に変換される。この3相
の交流電圧基準Vu*, Vv*, Vw*は比較器13でキャリ
ア発生部12から出力される正側と負側のキャリアと比
較されゲートパルスGPとして出力され、インバータ5は
このゲートパルスGPによりパルス幅変調(PWM)制御
され、PN間の直流電圧Vdpn が交流電圧基準Vu*, V
v*, Vw*に対応した交流電圧に変換され、3相交流電流
Iu,Iv,Iw の有効電流成分Iqf及び無効電流成分Idf
が有効電流基準Iqr及び無効電流基準Idrに対応した値
となるように制御される。
In FIG. 4, a DC power supply 1 is an AC power supply 1.
A converter 1c that obtains a positive DC voltage Vdp from a and a converter 1 that obtains a negative DC voltage Vdn from an AC power supply 1b
d is connected in series, and is smoothed between PN through an LC filter including reactors 1e and 1f and capacitors 2 and 3, and has a DC voltage Vdpn having a neutral point C (= Vdp + Vdn).
Is output. The DC voltage Vdpn having this neutral point C is
It is converted into a desired AC voltage by the NPC inverter 5 and supplied to the load 7 as three-phase AC currents Iu, Iv, Iw. The three-phase AC currents Iu, Iv, Iw are detected by the current transformer 6 as feedback currents Iuf, Ivf, Iwf, and are converted by the converter (3
Phase two-phase conversion) 9, the active current component Iqf and the reactive current component Idf
Is converted to a rectangular coordinate signal of The active current component Iqf and the reactive current component Idf are converted by the current controller 10 into an active current reference I
Compared with qr and the reactive current reference Idr, orthogonal coordinate signals of the effective voltage reference Eqr and the invalid voltage reference Edr are output so as to reduce the respective current deviations. These orthogonal coordinate signals Eqr and Edr are converted into three-phase AC voltage references Vu *, Vv * and Vw * by a conversion unit (two-phase three-phase conversion) 11. The three-phase AC voltage references Vu *, Vv *, Vw * are compared with the positive and negative carriers output from the carrier generation unit 12 by the comparator 13 and output as a gate pulse GP. Pulse width modulation (PWM) control is performed by the pulse GP, and the DC voltage Vdpn between PN is changed to the AC voltage reference Vu *, V
v *, Vw *, and is converted into an AC voltage corresponding to the active current component Iqf and the reactive current component Idf of the three-phase AC currents Iu, Iv, Iw.
Is controlled to a value corresponding to the active current reference Iqr and the reactive current reference Idr.

【0004】また、電圧検出器20、21により直流電
源1の正側と負側の直流電圧Vdp、Vdnが電圧フィード
バックVdpf 、Vdnf として検出され、その差電圧ΔV
d が各交流電圧基準Vu*, Vv*, Vw*に加算され、補正
された交流電圧基準Vu2*,Vv2*,Vw2* により差電圧Δ
Vd がゼロとなるようにインバータ5の交流出力電圧が
制御される。これにより、直流電源1の正側と負側の直
流電圧Vdp、Vdnに差が生じると、中性点電位が変動し
て差電圧ΔVd が生じ、該差電圧ΔVd をゼロとするよ
うに交流電圧基準Vu*, Vv*, Vw*を補正した交流電圧
基準Vu2*,Vv2*,Vw2* が比較器13に与えられる。こ
れにより、NPCインバータ5は正側と負側の出力電力
に差が生じるように制御され、中性点電位の変動を抑制
するように制御される。
The voltage detectors 20 and 21 detect the positive and negative DC voltages Vdp and Vdn of the DC power supply 1 as voltage feedbacks Vdpf and Vdnf, respectively.
d is added to each AC voltage reference Vu *, Vv *, Vw *, and the difference voltage Δ is calculated based on the corrected AC voltage reference Vu2 *, Vv2 *, Vw2 *.
The AC output voltage of the inverter 5 is controlled so that Vd becomes zero. Thus, when a difference occurs between the DC voltages Vdp and Vdn on the positive side and the negative side of the DC power supply 1, the neutral point potential fluctuates to generate a difference voltage ΔVd, and the AC voltage is set so that the difference voltage ΔVd becomes zero. The AC voltage references Vu2 *, Vv2 *, Vw2 * obtained by correcting the references Vu *, Vv *, Vw * are supplied to the comparator 13. As a result, the NPC inverter 5 is controlled so that a difference occurs between the output power on the positive side and the output power on the negative side, and is controlled so as to suppress the fluctuation of the neutral point potential.

【0005】例えば、正側の直流電圧Vdpが負側の直流
電圧Vdnより大きくなった場合、交流電圧基準Vu*, V
v*, Vw*を正方向へバイアスするように差電圧ΔVd が
加えられ、正側の直流電圧Vdpから供給される電力が増
加し、負側の直流電圧Vdnから供給される電力が減少す
るように補正制御され、結果として中性点電位の変動が
抑制される。
For example, when the positive side DC voltage Vdp becomes larger than the negative side DC voltage Vdn, the AC voltage references Vu *, V
The difference voltage ΔVd is applied so as to bias v * and Vw * in the positive direction, so that the power supplied from the positive DC voltage Vdp increases and the power supplied from the negative DC voltage Vdn decreases. And the fluctuation of the neutral point potential is suppressed as a result.

【0006】[0006]

【発明が解決しようとする課題】しかしながら、上述し
た従来の装置では、負荷変動や出力周波数変動に起因し
て、リアクトル1e,1fとコンデンサ2,3で成るL
Cフィルタの共振周波数で直流電圧が振動する場合があ
る。コンバータ1c,1dは、それぞれ直流電圧を制御
する図示しない電圧制御系を備え、その電圧制御応答と
上記共振周波数との関係で直流電圧が振動する場合があ
る。また、正側直流電圧Vdpと負側直流電圧Vdnが一致
しながら変動すると差電圧ΔVd が検出されないので、
上述した補正制御では直流電圧の変動を抑制することが
できない。また、インバータ5から出力される交流電流
の有効電流成分の変動により正側直流電圧Vdpと負側直
流電圧Vdnが同位相で変動すると差電圧ΔVd がゼロと
なるため直流電圧の変動を抑制することができない。
However, in the above-mentioned conventional device, the L composed of the reactors 1e and 1f and the capacitors 2 and 3 due to load fluctuations and output frequency fluctuations.
The DC voltage may oscillate at the resonance frequency of the C filter. Each of converters 1c and 1d includes a voltage control system (not shown) for controlling a DC voltage, and the DC voltage may vibrate depending on the relationship between the voltage control response and the resonance frequency. Further, if the positive DC voltage Vdp and the negative DC voltage Vdn fluctuate while matching, the difference voltage ΔVd is not detected, so that
The above-described correction control cannot suppress the fluctuation of the DC voltage. Further, when the positive DC voltage Vdp and the negative DC voltage Vdn fluctuate in the same phase due to the fluctuation of the effective current component of the AC current output from the inverter 5, the difference voltage ΔVd becomes zero. Can not.

【0007】そのため、従来装置ではコンバータの電圧
制御応答を遅くして対処せざるを得なく、十分に直流電
圧の変動を抑制することができなかった。そのため、負
荷として圧延機を駆動する電動機を適用した場合、負荷
変動に対する制御応答が遅くなり、制御出力トルクに変
動を与え、圧延作用に影響を与え、製品品質に悪影響を
及ぼす場合がある。
[0007] Therefore, in the conventional device, the voltage control response of the converter must be slowed to cope with it, and the fluctuation of the DC voltage cannot be sufficiently suppressed. Therefore, when an electric motor that drives a rolling mill is applied as a load, the control response to a load change becomes slow, the control output torque fluctuates, the rolling action is affected, and the product quality may be adversely affected.

【0008】本発明は上記問題を解消しようとしてなさ
れたもので、その目的とするところは、直流電圧の変動
分を検出して交流出力電流の有効電流成分を補正制御
し、直流電源のLC共振による直流電圧の振動現象を抑
制し、制御特性を改善したNPCインバータ装置を提供
することにある。
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. It is an object of the present invention to detect a fluctuation of a DC voltage to correct and control an effective current component of an AC output current, thereby achieving an LC resonance of a DC power supply. It is an object of the present invention to provide an NPC inverter device which suppresses a DC voltage oscillation phenomenon caused by the above and improves control characteristics.

【0009】[0009]

【課題を解決するための手段】上記目的を達成するた
め、本発明のNPCインバータ装置は次のように構成す
る。正側電圧と負側電圧に分割した中性点を有する直流
電圧をLCフィルタを介して出力する直流電源と、前記
直流電圧を所望の周波数の交流電圧に変換し負荷に交流
電流を供給するNPCインバータ手段と、有効電流基準
及び無効電流基準と前記交流電流の有効電流成分及び無
効電流成分の検出値とをそれぞれ比較して電流偏差を減
少させるように前記NPCインバータ手段を制御する電
流制御手段と、前記直流電圧の所定周波数以上の領域の
変動成分を補正信号として出力する補正手段を備え、こ
の補正信号により前記直流電圧の変動を抑制するように
前記有効電流基準を補正する。(請求項1) 正側電圧と負側電圧に分割した中性点を有する直流電圧
をLCフィルタを介して出力する直流電源と、前記直流
電圧をそれぞれ所望の周波数の交流電圧に変換しそれぞ
れの負荷に交流電流を供給する複数のNPCインバータ
手段と、有効電流基準及び無効電流基準と前記交流電流
の有効電流成分及び無効電流成分の検出値とをそれぞれ
比較して電流偏差を減少させるようにそれぞれの前記N
PCインバータ手段を制御する複数の電流制御手段と、
前記直流電圧の所定周波数以上の領域の変動成分を補正
信号として出力する補正手段を備え、この補正信号によ
り前記直流電圧の変動を抑制するように各電流制御手段
に与えられるそれぞれの有効電流基準を補正する。(請
求項2) 前記補正信号と前記有効電流基準に基づき、有効電流基
準の増大に応じて減少する第2補正信号を得る演算部を
それぞれ備え、この第2補正信号により前記直流電圧の
変動を抑制するように各電流制御手段に与えられるそれ
ぞれの有効電流基準を補正する。(請求項3) 前記演算部は、有効電流基準が所定値を越えるまでは前
記補正信号に一定のゲインを乗じた第2補正信号を出力
し、有効電流基準が所定値を越えたときは第2補正信号
をゼロにする。(請求項4) 前記補正手段は、前記LCフィルタの共振周波数に基づ
いて前記所定の周波数を決定する。(請求項5)
In order to achieve the above object, an NPC inverter device according to the present invention is configured as follows. A DC power supply that outputs a DC voltage having a neutral point divided into a positive voltage and a negative voltage through an LC filter, and an NPC that converts the DC voltage into an AC voltage having a desired frequency and supplies an AC current to a load Inverter means, and current control means for controlling the NPC inverter means so as to reduce the current deviation by comparing the active current reference and the reactive current reference with the detected values of the active current component and the reactive current component of the AC current, respectively. Correction means for outputting, as a correction signal, a fluctuation component of the DC voltage in a region of a predetermined frequency or higher, and the effective current reference is corrected by the correction signal so as to suppress the fluctuation of the DC voltage. (Claim 1) A DC power supply that outputs a DC voltage having a neutral point divided into a positive voltage and a negative voltage through an LC filter, and converts the DC voltage into an AC voltage having a desired frequency. A plurality of NPC inverter means for supplying an alternating current to the load; and a means for comparing the active current reference and the reactive current reference with the detection values of the active current component and the reactive current component of the alternating current, respectively, so as to reduce the current deviation. Said N
A plurality of current control means for controlling the PC inverter means;
A correction unit that outputs a fluctuation component of a region of a predetermined frequency or more of the DC voltage as a correction signal, and the respective effective current references given to each current control unit so as to suppress the fluctuation of the DC voltage by the correction signal. to correct. (Claim 2) A calculation unit is provided for obtaining a second correction signal that decreases in accordance with an increase in the active current reference based on the correction signal and the active current reference, and calculates a change in the DC voltage by the second correction signal. The respective effective current references provided to the respective current control means are corrected so as to suppress them. (Claim 3) The calculation section outputs a second correction signal obtained by multiplying the correction signal by a constant gain until the effective current reference exceeds a predetermined value, and outputs a second correction signal when the effective current reference exceeds a predetermined value. 2 Set the correction signal to zero. (Claim 4) The correction means determines the predetermined frequency based on a resonance frequency of the LC filter. (Claim 5)

【0010】[0010]

【発明の実施の形態】本発明の請求項1に対応するNP
Cインバータ装置の実施例を図1に示す。図1の構成に
おいて、30は正側の直流電圧検出値Vdpf と負側の直
流電圧検出値Vdnf から補正信号Iqcを得る有効電流補
正部で、正側の直流電圧検出値Vdpf と負側の直流電圧
検出値Vdnf の加算値(Vdpf +Vdnf )、すなわち直
流電源1のPN間の直流電圧Vdpn を求める加算器31
と、PN間の直流電圧Vdpn が変動するとき、その変動
成分の所定周波数以下の直流分を含む低周波領域を除去
し、高周波領域のみを補正信号Iqcとして出力するハイ
パスフィルタ32で構成される。33は補正信号Iqcを
有効電流基準Iqrに加算する加算器である。その他は従
来と同様に構成される。
DESCRIPTION OF THE PREFERRED EMBODIMENTS NP according to claim 1 of the present invention
FIG. 1 shows an embodiment of the C inverter device. In the configuration of FIG. 1, reference numeral 30 denotes an effective current correction unit that obtains a correction signal Iqc from the positive DC voltage detection value Vdpf and the negative DC voltage detection value Vdnf, and includes a positive DC voltage detection value Vdpf and a negative DC voltage. An adder 31 for obtaining an addition value (Vdpf + Vdnf) of the voltage detection value Vdnf, that is, a DC voltage Vdpn between PN of the DC power supply 1.
When the DC voltage Vdpn between the PNs fluctuates, a high-pass filter 32 that removes a low-frequency region including a DC component of a fluctuation component equal to or lower than a predetermined frequency and outputs only a high-frequency region as a correction signal Iqc. An adder 33 adds the correction signal Iqc to the effective current reference Iqr. Otherwise, the configuration is the same as that of the related art.

【0011】上記構成において、NPCインバータ5
は、有効電流基準Iqr及び無効電流基準Idrに基づいて
従来と同様に3相の交流電流Iu,Iv,Iw を出力し、直
流電源1の正側と負側の直流電圧Vdp、Vdnに差が生じ
差電圧ΔVd が検出されると、従来と同様に交流電圧基
準Vu*, Vv*, Vw*が補正制御され、中性点電位の変動
を抑制するように補正制御する。
In the above configuration, the NPC inverter 5
Outputs the three-phase AC currents Iu, Iv, Iw based on the active current reference Iqr and the reactive current reference Idr in the same manner as before, and the difference between the positive and negative DC voltages Vdp, Vdn of the DC power supply 1 is different. When the resulting difference voltage ΔVd is detected, the AC voltage references Vu *, Vv *, Vw * are corrected and controlled in the same manner as in the prior art, and the correction control is performed so as to suppress the fluctuation of the neutral point potential.

【0012】本実施例では、更に、直流電源1のPN間
の直流電圧Vdpn が変動するとき、有効電流補正部30
から、その変動成分の所定周波数以下の直流分を含む低
周波領域を除去した高周波領域の補正信号Iqcが出力さ
れ、加算器33を介して有効電流基準Iqrに加算され
る。これにより、PN間の直流電圧Vdpn が変動する
と、その電圧変動を抑制するようにNPCインバータ5
から出力される交流電流Iu,Iv,Iw の有効電流成分が
補正制御される。例えば、PN間の直流電圧Vdpnが増
加方向に変化すると有効電流成分が増加する方向に補正
され、Vdpn が減少方向に変化すると有効電流成分が減
少する方向に補正され、結果としてPN間の直流電圧V
dpn の変動を抑制するように作用する。
In this embodiment, when the DC voltage Vdpn between PN of the DC power supply 1 fluctuates, the effective current correction unit 30
Then, a correction signal Iqc in a high frequency region from which a low frequency region including a direct current component below a predetermined frequency of the fluctuation component is removed is added to an effective current reference Iqr via an adder 33. As a result, when the DC voltage Vdpn between the PNs fluctuates, the NPC inverter 5 is controlled so as to suppress the voltage fluctuation.
The effective current components of the alternating currents Iu, Iv, Iw output from the CPU are corrected and controlled. For example, when the DC voltage Vdpn between PN changes in the increasing direction, the effective current component is corrected to increase, and when the Vdpn changes in the decreasing direction, the effective current component is corrected to decrease. As a result, the DC voltage between PN is corrected. V
Acts to suppress fluctuations in dpn.

【0013】図2(a)はハイパスフィルタ32の特性
を示す伝達関数であり、32aは入力信号の所定の時定
数Tで決まる周波数以下の直流分を含む低周波領域のみ
を通過させる伝達ブロック、32bは伝達ブロック32
aを通過した入力信号の低周波領域を該入力信号から減
じる減算器、32cは減算器32bの出力信号を所定レ
ベルに変換し補正信号Iqcとして出力する増幅器であ
る。上記構成により、入力信号(PN間の直流電圧Vdp
n の検出値)Vdpn から所定の時定数Tで決まる周波数
以下の直流分を含む低周波領域が除去された高周波成分
のみが補正信号Iqcとして出力される。
FIG. 2A is a transfer function showing the characteristics of the high-pass filter 32. Reference numeral 32a denotes a transfer block that passes only a low-frequency region including a DC component whose frequency is equal to or lower than a frequency determined by a predetermined time constant T of the input signal. 32b is a transmission block 32
A subtractor 32c for subtracting the low frequency region of the input signal having passed through the input signal from the input signal, and an amplifier 32c for converting the output signal of the subtractor 32b to a predetermined level and outputting it as a correction signal Iqc. With the above configuration, the input signal (DC voltage Vdp between PN
Only the high frequency component from which the low frequency region including the direct current component below the frequency determined by the predetermined time constant T has been removed from the detected value of Vdpn) is output as the correction signal Iqc.

【0014】本実施例によれば、負荷変動や出力周波数
変動に起因し、直流電源1のLCフィルタの共振周波数
に共振して直流電圧が変動するとき、ハイパスフィルタ
32aの時定数Tを適宜に設定することにより、直流電
圧の変動を効果的に抑制するダンピング効果が得られ、
直流電源として動作するコンバータの電圧制御応答を発
振現象を生じさせることなく良くすることができる。従
って、負荷として圧延機を駆動する電動機を適用する場
合、電動機の制御出力トルクの変動を抑制し、圧延作用
に与える影響を抑制し、製品品質に悪影響を与えるとい
う問題も解消される。
According to this embodiment, when the DC voltage fluctuates due to the resonance frequency of the LC filter of the DC power supply 1 due to the load fluctuation or the output frequency fluctuation, the time constant T of the high-pass filter 32a is appropriately adjusted. By setting, a damping effect that effectively suppresses the fluctuation of the DC voltage is obtained,
The voltage control response of the converter operating as a DC power supply can be improved without causing an oscillation phenomenon. Therefore, when an electric motor that drives a rolling mill is applied as a load, the problem that the fluctuation of the control output torque of the electric motor is suppressed, the effect on the rolling action is suppressed, and the product quality is adversely affected is also solved.

【0015】本発明の請求項2に対応するNPCインバ
ータ装置の実施例を図3に示す。この実施例は、1つの
直流電源1から出力された中性点Cを有する直流電圧を
複数のNPCインバータ51 〜5n に供給し、それぞれ
電動機(負荷)71 〜7n に独立した交流電流を供給す
る共通電源システムである。
FIG. 3 shows an embodiment of an NPC inverter device according to claim 2 of the present invention. In this embodiment, a DC voltage having a neutral point C output from one DC power supply 1 is supplied to a plurality of NPC inverters 5 1 to 5 n , and each of the motors (loads) 7 1 to 7 n has an independent AC. It is a common power supply system that supplies current.

【0016】図3において、151 〜15n はそれぞれ
の有効(トルク)電流基準Iqr及び無効(励磁)電流基
準Idrに基づいてNPCインバータ51 〜5n を制御し
電動機(負荷)71 〜7n を制御する制御部で、それぞ
れの有効電流基準Iqr1 〜Iqrn に補正信号Iqcを加算
する加算器331 〜33n が設けられている。
[0016] In FIG. 3, 15 1 to 15 n are respectively valid (torque) current reference Iqr and reactive (excitation) on the basis of the current reference Idr NPC inverter 5 1 to 5 controls the n and motor (load) 7 1 - in the control unit for controlling the 7 n, an adder 33 1 ~ 33 n for adding the correction signal Iqc to each of the active current reference Iqr 1 ~Iqr n it is provided.

【0017】上記構成において、共通の直流電源のPN
間の電圧が変動すると、有効電流補正部30からその変
動成分の所定周波数以下の直流分を含む低周波領域を除
去した高周波領域の補正信号Iqcが各トルク電流基準I
qr1 〜Iqrn に加算され、各NPCインバータ51 〜5
n から出力される交流電流の有効(トルク)電流成分
が、PN間の電圧変動を抑制するように補正制御され
る。
In the above configuration, the common DC power supply PN
When the voltage fluctuates, the correction signal Iqc in the high frequency region obtained by removing the low frequency region including the direct current component below the predetermined frequency of the fluctuation component from the effective current correction unit 30 is applied to each torque current reference I.
It is added to qr 1 ~Iqr n, each NPC inverter 5 1 to 5
The effective (torque) current component of the alternating current output from n is corrected and controlled so as to suppress the voltage fluctuation between PN.

【0018】本実施例の場合、各NPCインバータ51
〜5n はそれぞれ独立して運転することができ、それぞ
れの出力周波数が異なり、それぞれの周波数差と直流電
源1のLC共振周波数との関係で直流電圧が振動するこ
とがあるが、有効電流補正部30のハイパスフィルタ3
2の時定数Tを適当な値に設定することにより直流電圧
の振動を抑制することができる。
In this embodiment, each NPC inverter 5 1
To 5 n it can be operated independently, different respective output frequency, but the DC voltage in relation to each of the frequency difference and the LC resonant frequency of the DC power source 1 may vibrate, active current correction High-pass filter 3 of section 30
By setting the time constant T of 2 to an appropriate value, the oscillation of the DC voltage can be suppressed.

【0019】本発明の請求項3,4に対応するNPCイ
ンバータ装置の実施例を図2(b)に示す。この実施例
は、図3の実施例に更に演算部341 〜34n を追加し
たものである。
FIG. 2B shows an embodiment of an NPC inverter device according to claims 3 and 4 of the present invention. The examples are further added the arithmetic unit 34 1 to 34C n to the embodiment of FIG.

【0020】この演算部341 〜34n は、それぞれ有
効電流基準Iqr1 〜Iqrn に応じてゲインの変化する増
幅器でなり、有効電流補正部30から出力された補正信
号Iqcに対して、有効電流基準Iqr1 〜Iqrn の増大に
応じて減少するゲインを乗じた第2補正信号Iqc1 〜I
qcn を出力する。この第2補正信号により直流電圧の変
動を抑制するように各電流制御手段に与えられるそれぞ
れの有効電流基準を補正する。
[0020] The arithmetic unit 34 1 to 34C n becomes the gain varying amplifier according to active current reference Iqr 1 ~Iqr n respectively, with respect to the correction signal Iqc output from the active current correction unit 30, the effective the second correction signal Iqc 1 ~I multiplied by the reduced gain with an increase of the current reference Iqr 1 ~Iqr n
Outputs qc n . Each effective current reference given to each current control means is corrected by the second correction signal so as to suppress the fluctuation of the DC voltage.

【0021】図2(c)は演算部341 〜34n のゲイ
ン特性で、有効電流基準Iqr1 〜Iqrn の大きさ(絶対
値)に対するゲイン変化の関係を示したものである。特
性c1 は、有効電流基準Iqr1 〜Iqrn の大きさ(絶対
値)の増大に応じて演算部341 〜34n のゲインを減
少させ、所定の有効電流基準Iqrx においてゲインをゼ
ロにする例であり、請求項3に対応するものである。
[0021] FIG. 2 (c) in the gain characteristic of the arithmetic unit 34 1 ~34 n, shows the relationship between the gain change with respect to the active current reference Iqr 1 ~Iqr n size (absolute value). Characteristic c1 is an example of the gain to zero in the effective current reference Iqr 1 size of ~Iqr n decreases the gain of the arithmetic unit 34 1 to 34C n in accordance with the increase of (absolute value), a predetermined active current reference Iqrx Which corresponds to claim 3.

【0022】特性c2 は、有効電流基準Iqr1 〜Iqrn
の大きさ(絶対値)が所定値Iqrx以下ではゲインを一
定とし、Iqrx を越えるとゲインをゼロとする例であ
り、請求項4に対応するものである。
The characteristic c2 has an effective current reference Iqr 1 to Iqr n
This is an example in which the gain is constant when the magnitude (absolute value) is equal to or less than a predetermined value Iqrx, and the gain is zero when the magnitude exceeds Iqrx.

【0023】請求項3,4の実施例によれば、共通電源
システムの複数のNPCインバータ51 〜5n でそれぞ
れの電動機(負荷)71 〜7n に交流電流を供給する場
合に、所定の有効電流基準Iqrx 以下の有効電流成分の
交流電流を供給しているNPCインバータにのみ第2補
正信号Iqcを与え、所定の有効電流基準Iqrx を越える
有効電流成分の交流電流を供給しているNPCインバー
タには第2補正信号Iqcを与えないように制御して、直
流電圧の変動成分を抑制する制御を軽負荷(無負荷を含
む)のNPCインバータで行うようにすることができ
る。従って、直流電源のLCフィルタの共振により直流
電圧が振動し、電圧変動を抑制する場合に、各NPCイ
ンバータの運転状況をみて、出力電流に余裕の有るNP
Cインバータで補正制御が行われ、圧延負荷のある電動
機(負荷)に交流電流を供給しているNPCインバータ
には第2補正信号Iqcが与えられず圧延作用に影響を及
ぼすことがなくなる。
According to an embodiment of the claims 3 and 4, when supplying a plurality of NPC inverters 5 1 to 5 n, respectively of the electric motor (load) 7 1 to 7-n to the alternating current of the common power system, a predetermined The second correction signal Iqc is supplied only to the NPC inverter that supplies the AC current of the active current component equal to or less than the active current reference Iqrx of the NPC, and the NPC that supplies the AC current of the active current component exceeding the predetermined active current reference Iqrx is supplied. By controlling the inverter so as not to apply the second correction signal Iqc, the control for suppressing the fluctuation component of the DC voltage can be performed by a light-load (including no-load) NPC inverter. Therefore, when the DC voltage oscillates due to the resonance of the LC filter of the DC power supply and suppresses the voltage fluctuation, the operation status of each NPC inverter is checked, and the NP having the output current with a margin is provided.
The correction control is performed by the C inverter, and the NPC inverter that supplies the AC current to the electric motor (load) with the rolling load is not supplied with the second correction signal Iqc, so that the rolling operation is not affected.

【0024】以上の説明では、直流電源1のPN間の直
流電圧を、正側の直流電圧検出値Vdpf と負側の直流電
圧検出値Vdnf を加算して求める例で示したが、PN間
の直流電圧を直接検出する電圧検出器を用いても同様に
実施することができる。
In the above description, the DC voltage between PN of the DC power supply 1 is obtained by adding the positive DC voltage detection value Vdpf and the negative DC voltage detection value Vdnf. The present invention can be similarly implemented by using a voltage detector that directly detects a DC voltage.

【0025】[0025]

【発明の効果】本発明によれば、直流電圧の変動分を検
出して該変動電圧を抑制するように交流出力電流の有効
電流成分を補正制御することができ、直流電源のLC共
振による直流電圧の振動現象を抑制して安定した直流電
圧とすることができ、制御特性を改善したNPCインバ
ータ装置を提供することができる。
According to the present invention, the fluctuation of the DC voltage can be detected and the effective current component of the AC output current can be corrected and controlled so as to suppress the fluctuation. A stable DC voltage can be obtained by suppressing the voltage oscillation phenomenon, and an NPC inverter device with improved control characteristics can be provided.

【図面の簡単な説明】[Brief description of the drawings]

【図1】本発明の請求項1に対応するNPCインバータ
装置の実施例の構成図
FIG. 1 is a configuration diagram of an embodiment of an NPC inverter device according to claim 1 of the present invention.

【図2】(a)ハイパスフィルタ32の特性を示すブロ
ック構成図、(b)本発明の請求項3、4に対応するN
PCインバータ装置の実施例の要部構成図、(c)演算
部341 〜34n のゲイン特性図
FIG. 2 (a) is a block diagram showing the characteristics of a high-pass filter 32, and FIG. 2 (b) is a block diagram of N according to claims 3 and 4 of the present invention.
Main configuration diagram of an embodiment of a PC inverter device, (c) gain characteristic diagram of the arithmetic unit 34 1 to 34C n

【図3】本発明の請求項2に対応するNPCインバータ
装置の実施例の構成図
FIG. 3 is a configuration diagram of an embodiment of an NPC inverter device according to claim 2 of the present invention.

【図4】従来のNPCインバータ装置の構成図FIG. 4 is a configuration diagram of a conventional NPC inverter device.

【符号の説明】[Explanation of symbols]

1…直流電源 1a,1b…交
流電源 1c,1d…コンバータ 1e,1f…リ
アクトル 2,3…コンデンサ 5,51 〜5n …NPCインバータ 6…変流器 7,71 〜7n …負荷(電動機) 9…変換器
(3相2相変換) 10…電流制御器 11…変換器
(2相3相変換) 12…キャリア発生部 13…比較器 151 〜15n …電流制御部 20,21…電圧検出器 30…有効電
流補正部 31…加算器 32…ハイパ
スフィルタ 33,331 〜33n …加算器 341 〜34
n …演算部
1 ... DC power source 1a, 1b ... AC power source 1c, 1d ... converter 1e, 1f ... reactor 2 ... capacitor 5,5 1 to 5 n ... NPC inverter 6 ... current transformer 7, 7 1 to 7-n ... load ( 9) Converter (three-phase two-phase conversion) 10 ... Current controller 11 ... Converter (two-phase three-phase conversion) 12 ... Carrier generation unit 13 ... Comparator 15 1 to 15 n ... Current control unit 20, 21 ... voltage detector 30 ... active current correction unit 31 ... adder 32 ... high-pass filter 33, 33 1 ~ 33 n ... adder 34 1-34
n … Calculation unit

Claims (5)

(57)【特許請求の範囲】(57) [Claims] 【請求項1】正側電圧と負側電圧に分割した中性点を有
する直流電圧をLCフィルタを介して出力する直流電源
と、前記直流電圧を所望の周波数の交流電圧に変換し負
荷に交流電流を供給するNPCインバータ手段と、有効
電流基準及び無効電流基準と前記交流電流の有効電流成
分及び無効電流成分の検出値とをそれぞれ比較して電流
偏差を減少させるように前記NPCインバータ手段を制
御する電流制御手段と、前記直流電圧の所定周波数以上
の領域の変動成分を補正信号として出力する補正手段を
備え、この補正信号により前記直流電圧の変動を抑制す
るように前記有効電流基準を補正することを特徴とする
NPCインバータ装置。
1. A DC power supply for outputting a DC voltage having a neutral point divided into a positive voltage and a negative voltage via an LC filter, converting the DC voltage into an AC voltage having a desired frequency, and applying the AC voltage to a load. NPC inverter means for supplying a current, and controlling the NPC inverter means to reduce a current deviation by comparing the active current reference and the reactive current reference with the detection values of the active current component and the reactive current component of the AC current, respectively. And a correction unit that outputs a fluctuation component of the DC voltage in a region of a predetermined frequency or more as a correction signal, and corrects the effective current reference so as to suppress the fluctuation of the DC voltage by the correction signal. An NPC inverter device, characterized in that:
【請求項2】正側電圧と負側電圧に分割した中性点を有
する直流電圧をLCフィルタを介して出力する直流電源
と、前記直流電圧をそれぞれ所望の周波数の交流電圧に
変換しそれぞれの負荷に交流電流を供給する複数のNP
Cインバータ手段と、有効電流基準及び無効電流基準と
前記交流電流の有効電流成分及び無効電流成分の検出値
とをそれぞれ比較して電流偏差を減少させるようにそれ
ぞれの前記NPCインバータ手段を制御する複数の電流
制御手段と、前記直流電圧の所定周波数以上の領域の変
動成分を補正信号として出力する補正手段を備え、この
補正信号により前記直流電圧の変動を抑制するように各
電流制御手段に与えられるそれぞれの有効電流基準を補
正することを特徴とするNPCインバータ装置。
2. A DC power supply for outputting a DC voltage having a neutral point divided into a positive voltage and a negative voltage via an LC filter, and converting the DC voltage into an AC voltage having a desired frequency. Multiple NPs that supply alternating current to the load
C inverter means for controlling each of the NPC inverter means so as to reduce the current deviation by comparing the active current reference and the reactive current reference with the detected values of the active current component and the reactive current component of the AC current, respectively. Current control means, and correction means for outputting a fluctuation component of the DC voltage in a region of a predetermined frequency or higher as a correction signal, and the correction signal is given to each current control means so as to suppress the fluctuation of the DC voltage. An NPC inverter device for correcting each effective current reference.
【請求項3】請求項2に記載のNPCインバータ装置に
おいて、前記補正信号と前記有効電流基準に基づき、有
効電流基準の増大に応じて減少する第2補正信号を得る
演算部をそれぞれ備え、この第2補正信号により前記直
流電圧の変動を抑制するように各電流制御手段に与えら
れるそれぞれの有効電流基準を補正することを特徴とす
るNPCインバータ装置。
3. The NPC inverter device according to claim 2, further comprising an arithmetic unit for obtaining a second correction signal that decreases in accordance with an increase in the effective current reference, based on the correction signal and the effective current reference. An NPC inverter device wherein each effective current reference provided to each current control means is corrected so as to suppress the fluctuation of the DC voltage by a second correction signal.
【請求項4】請求項3に記載のNPCインバータ装置に
おいて、前記演算部は、有効電流基準が所定値を越える
までは前記補正信号に一定のゲインを乗じた第2補正信
号を出力し、有効電流基準が所定値を越えたときは第2
補正信号をゼロにすることを特徴とするNPCインバー
タ装置。
4. The NPC inverter device according to claim 3, wherein the arithmetic unit outputs a second correction signal obtained by multiplying the correction signal by a constant gain until the effective current reference exceeds a predetermined value. When the current reference exceeds a predetermined value, the second
An NPC inverter device for setting a correction signal to zero.
【請求項5】請求項1乃至請求項4のいずれかに記載の
NPCインバータ装置において、前記補正手段は、前記
LCフィルタの共振周波数に基づいて前記所定の周波数
を決定することを特徴とするNPCインバータ装置。
5. The NPC inverter device according to claim 1, wherein said correction means determines said predetermined frequency based on a resonance frequency of said LC filter. Inverter device.
JP32999095A 1995-12-19 1995-12-19 NPC inverter device Expired - Lifetime JP3186962B2 (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
JP32999095A JP3186962B2 (en) 1995-12-19 1995-12-19 NPC inverter device
US08/766,476 US5790396A (en) 1995-12-19 1996-12-12 Neutral point clamped (NPC) inverter control system
CA002193269A CA2193269C (en) 1995-12-19 1996-12-18 Npc inverter control system
KR1019960067912A KR100240905B1 (en) 1995-12-19 1996-12-19 Npc inverter control system
CN96121324A CN1055580C (en) 1995-12-19 1996-12-19 Control system for NPC inverse transformer

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP32999095A JP3186962B2 (en) 1995-12-19 1995-12-19 NPC inverter device

Publications (2)

Publication Number Publication Date
JPH09172783A JPH09172783A (en) 1997-06-30
JP3186962B2 true JP3186962B2 (en) 2001-07-11

Family

ID=18227546

Family Applications (1)

Application Number Title Priority Date Filing Date
JP32999095A Expired - Lifetime JP3186962B2 (en) 1995-12-19 1995-12-19 NPC inverter device

Country Status (1)

Country Link
JP (1) JP3186962B2 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5910892A (en) * 1997-10-23 1999-06-08 General Electric Company High power motor drive converter system and modulation control
JP2006304456A (en) * 2005-04-19 2006-11-02 Fuji Electric Systems Co Ltd Power converter
JP4750553B2 (en) * 2005-12-28 2011-08-17 東芝シュネデール・インバータ株式会社 Electric motor control device
ES2424867T3 (en) * 2006-04-24 2013-10-09 Panasonic Corporation Inverter device and air conditioner
JP4067021B2 (en) * 2006-07-24 2008-03-26 ダイキン工業株式会社 Inverter device
JP2009060723A (en) * 2007-08-31 2009-03-19 Fuji Electric Systems Co Ltd Controller for power conversion equipment and static auxiliary power supply for vehicle
WO2012093504A1 (en) * 2011-01-06 2012-07-12 Mitsubishi Electric Corporation Neutral point clamped converter with variable voltage generator in order to stabilise the neutral voltage
JP5822732B2 (en) * 2012-01-11 2015-11-24 東芝三菱電機産業システム株式会社 3-level power converter
JP2015195656A (en) * 2014-03-31 2015-11-05 三菱電機株式会社 Power conversion device
JP2016082761A (en) * 2014-10-20 2016-05-16 株式会社明電舎 Three-phase neutral point clamp type power conversion device
JP6264257B2 (en) * 2014-10-20 2018-01-24 株式会社明電舎 Three-phase neutral point clamp type power converter
US10110117B2 (en) * 2015-10-15 2018-10-23 Mitsubishi Electric Corporation Multilevel power conversion device
CN110739708B (en) * 2019-12-04 2023-03-21 国网青海省电力公司电力科学研究院 Compensation device for +/-800 kV power transmission and transformation main equipment air load and temperature rise test system

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