JPS58136285A - Operating method for induction motor - Google Patents

Abstract

PURPOSE:To suppress the resonance phenomenon of an induction motor by increasing the slip frequency of the motor when the output frequency of a power source for driving the motor coincides with the intrinsic vibration of a mechanical system and operating the motor, thereby minimizing the sacrifice of the operating efficiency. CONSTITUTION:A DC power source 1 is inputted through an input filter circuit 2 to a VVVF inverter 5, the inverter 5 is controlled by a calculator 6 on the basis of the output of a sensor 7 such as a tachometer generator or the like and the slip frequency fs determined from the rotor current, thereby driving an induction motor 8 which is coupled to a mechanical system 9. When the output frequency of the inverter 5 coincides with the intrinsic vibration or its integer times of the mechanical system 9 at this time, the motor 8 is operated at the slip frequency larger than the slip frequency determined by the necessary torque. Accordingly, the sacrifice of the operating efficiency is minimized, thereby suppressing the resonance phenomenon which occurs between an electric system and the mechanical system.

Description

【発明の詳細な説明】 この発明は、特に、可変電圧・可変周波数電源を用いて
誘導電動機を運転する場合の運転方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a method of operating an induction motor using a variable voltage/variable frequency power source.

誘導電動機の発生トルクは、その印加電圧と入力周波数
のいずれかを制御することにより制御することができる
ので、従来一般には、可変電圧・可変周波数電源（以下
、ＶＶＶＦインバータと云う。）を用い、その出力電圧
Ｖ・出方周波数比′Ｖ／１Ｉｘｒが一定になるように制
御しながら出方周波数ｔｚｘｒを下記の如く制御して必
要トルクを得る。The torque generated by an induction motor can be controlled by controlling either the applied voltage or the input frequency, so conventionally, a variable voltage/variable frequency power source (hereinafter referred to as a VVVF inverter) is generally used. While controlling the output voltage V/output frequency ratio 'V/1Ixr to be constant, the output frequency tzxr is controlled as described below to obtain the necessary torque.

力行運転時　ｆｌＮＦ＝＝ｆＭ−ｆｓ　　　　−・−α
）回生運転時　ｔ　ｚｘｒ＝ｆｓｔ＋ｆｓ’　　　　−
（２）但し、ｆＭ＝誘導電動機の回転周波数 この必要トルクから定まる誘導電動機の回転子電流はす
ペシ周波数ｆｓ　　の関数であるので、＃回転子電流ｌ
ｉｔ　　から上記（１）式と（温式のすべ多周波数ｆｓ
　　が決定され、回転周波数ｆｘ　は誘導電動機軸に直
結される速度発電機等のセンサーの出方から得る。落１
図に上記の制御を行う為の電源装置を示す。図において
、１は直流電源、２は入力フィルタ回路、３はリアクト
ル、４はコンデンサ、５はＶＶＶＦインバータ、＠は周
波数演算装置で上記センサー１の出方と上記回転子電流
から定まるすベシ周波数ｆｊ　　に基いて上記（１）式
と０）式を演算する。８は誘導電動機で機械系９を駆動
する。During power running flNF==fM-fs −・−α
) During regenerative operation t zxr=fst+fs' -
(2) However, fM = rotational frequency of the induction motor Since the rotor current of the induction motor determined from this required torque is a function of the frequency fs, # rotor current l
From it, the above equation (1) and (all the multi-frequency fs of the warm equation)
is determined, and the rotational frequency fx is obtained from the output of a sensor such as a speed generator directly connected to the induction motor shaft. Drop 1
The figure shows a power supply device for performing the above control. In the figure, 1 is a DC power supply, 2 is an input filter circuit, 3 is a reactor, 4 is a capacitor, 5 is a VVVF inverter, @ is a frequency calculation device, and the frequency fj is determined from the output of the sensor 1 and the rotor current. The above equations (1) and 0) are calculated based on . 8 drives a mechanical system 9 with an induction motor.

しかし、機械系９の固有振動数ｔｆｏ　とした場合、セ
ンサー７の出力が固有振動数ｆＯで振動する為上記電源
装置内の例えば演算おくれ等により誘導電動機の実際の
すベク周波数ｆｓ　　が第２図に示す如くほぼ周波数ｆ
Ｏで振動する。However, when the natural frequency of the mechanical system 9 is tfo, the output of the sensor 7 vibrates at the natural frequency fO, so due to the calculation delay in the above power supply, for example, the actual total frequency of the induction motor becomes fs as shown in Fig. 2. As shown in , approximately the frequency f
It vibrates at O.

この結果、固有振動数ｆＯが出力周波数帯域内にある時
は、回転子電流だけでなく、入力フィルタ回路２のリア
クトル３の電流、コンデンサ４の電圧本固有振動数ｔｏ
　　で振動するようになり出力周波数Ｈｙｒ　＝　ｘｘ
ｔｏ　（ｐｔ　＝　１．２．３・・・）である時には、
電気系と機械系との共振現象が発生する。As a result, when the natural frequency fO is within the output frequency band, the natural frequency to
It starts to vibrate and the output frequency Hyr = xx
When to (pt = 1.2.3...),
A resonance phenomenon occurs between the electrical system and the mechanical system.

この発明は、上記した従来の欠点を除去する為になされ
たもので、電源の可制御の出力周波数が誘導電動機負荷
の固有振動数もしくはその整数倍になる時には、すべり
周波数を、誘導電動機特性で定まる必要トルクの為のす
べり周波数より大にすることにエフ、運転効率の犠牲を
最小限にとどめて電気系と機械系の共振をおさえること
ができる誘導電動機の運転方法を提供することを目的と
する。This invention was made to eliminate the above-mentioned conventional drawbacks. When the controllable output frequency of the power supply is the natural frequency of the induction motor load or an integer multiple thereof, the slip frequency can be changed based on the induction motor characteristics. The purpose of this invention is to provide a method of operating an induction motor that can minimize the sacrifice of operating efficiency and suppress resonance between the electrical and mechanical systems by increasing the slip frequency to a value higher than the required torque. do.

以下、この発明の一実施例を図について説明する。An embodiment of the present invention will be described below with reference to the drawings.

第３図は、誘導電動機がその特性で定まるすべり周波数
ｆ５　　（この時のすべりｆＳｏ　　とする。）で運転
される場合のすべ＃）Ｓ−回転子電流（ＩＯ特性を示し
たもので、ΔＳはすべ多周波数ｆｓの振動振巾に比例す
るすべりＳの振動振巾、Δ！１は回転子電流■の振動振
巾である。この発明では、ｆｌｌＮ’　：　ＮＸｆＯの
時に、第４図に示す如く、上記すべり周波数ｆ５↓り大
であるすべり周波数（この時のすべりＳ　：　ＳＭ　’
）　ＳＯとする。）で誘導電動機を運転する。ＳＮ＞Ｓ
Ｏにすると両図の比較から明らかなように、５−ＩＮ　
　％性の傾ｆ０が小さくなるので、回転子電流■Ｒの振
動振巾が第３図の場合より小さくなる。従って、前記し
た振動がおさえられる。このように丁ベク周波数を大き
くすると、誘導電動機のインピーダンスが小さくなって
発生トルクが小さくなるので、この発明では、上記した
ようＶｃｆｒｙ　＝　Ｎｘｆｏの場合にのみすベシ周波
数ｆ５　　エ勺大きいすべり周波数で運転しトルクの減
少を最小限にとどめる。Figure 3 shows the S-rotor current (IO characteristic) when the induction motor is operated at a slip frequency f5 (the slip at this time is fSo) determined by its characteristics, and ΔS is The vibration amplitude of the slip S, Δ!1, which is proportional to the vibration amplitude of the multi-frequency fs, is the vibration amplitude of the rotor current ■.In this invention, when fllN' : NXfO, as shown in FIG. , the slip frequency that is greater than the above slip frequency f5↓ (slip S at this time: SM'
) S.O. ) to drive an induction motor. SN>S
When set to O, as is clear from the comparison of both figures, 5-IN
Since the slope f0 of the % characteristic becomes smaller, the vibration amplitude of the rotor current ■R becomes smaller than in the case of FIG. 3. Therefore, the vibrations mentioned above are suppressed. When the slip frequency is increased in this way, the impedance of the induction motor becomes smaller and the generated torque becomes smaller. Therefore, in this invention, as mentioned above, when Vcfry = Nxfo, the slip frequency f5 is operated at a large slip frequency. and minimize the decrease in torque.

以上の如く、この発明によれば、誘導電動機を駆動する
電源の出力周波数が誘導電動機に軸結される機械系の固
有振動数もしくはその整数倍にはぼ一致する帯域におい
てのみすべり周波数を誘導電動機の特性より必要トルク
に対して定めたすべり周波数より太きくして運転するこ
とにより、運転効率の犠牲を最小限におさえて電気系と
機械系との間に生じる共振現象をおさえることができる
。As described above, according to the present invention, the slip frequency of the induction motor can be adjusted only in a band in which the output frequency of the power source that drives the induction motor closely matches the natural frequency of the mechanical system connected to the induction motor or an integral multiple thereof. By operating at a slip frequency greater than the one determined for the required torque based on the characteristics of , it is possible to minimize the sacrifice in operating efficiency and suppress the resonance phenomenon that occurs between the electrical system and the mechanical system.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は、可変電圧可変周波数電源で誘導電動機を運転
する場合の運転方法を説明する為のブロック図、第２図
は上記運転方法の問題点を説明する為の図、第３及び第
４図は、この発明による誘導電動機の運転方法の実施例
を説明する為のすべり一回転子電流特性図である。 図において、５・・・可変電圧可変周波数電源、６・・
・周波数５セ誉装置、８・・・誘導電動機、９・・・機
械系。 代理人　　　葛　　　野　　　信　　　−峙間 手続補正書（自づ６） 特許庁長官殿 １、事件の表示　　　　特願昭　　５７−８４６７号３
、補正をする者 代表者片山仁へ部 ５、　補正の対家 明細書の発１（）１の詳細な説明の捕 ６、　補正の内容 （１）　明ｍ　ＶＩ：（７）第２頁第４行のｒ　／ＩＮ
ｖ−ｊＭ−ｆＢ　ｊとあるのを［ｆ工ＭＶ”””ｆ　Ｍ
＋ｆ　Ｓ’ＪとＫ］正する。 （２）同第２−０第５行の’　／Ｉｎｖ”ｆＭ十ｆｓＪ
とあるのを’　／ＩＮＶ”／　Ｍ　’　ｆ　Ｓ　Ｊと訂
正する。 （３）同第３頁第９行、Ｍ４４頁第８及び嬉１８行にｒ
　ｊｚＨｖ−Ｎｘｆ□　Ｊとあるのを’　ｂＮＶ’＝Ｎ
’１０　Ｊと夫々ｇＪ圧する。 以上Figure 1 is a block diagram for explaining the operation method when operating an induction motor with a variable voltage variable frequency power supply, Figure 2 is a diagram for explaining the problems of the above operation method, and Figures 3 and 4 are for explaining the problem of the above operation method. The figure is a slip rotor current characteristic diagram for explaining an embodiment of the method of operating an induction motor according to the present invention. In the figure, 5...variable voltage variable frequency power supply, 6...
・Frequency 5 SEHO device, 8...Induction motor, 9...Mechanical system. Agent Makoto Kuzuno - Written amendment to inter-procedural proceedings (Jizu 6) Commissioner of the Japan Patent Office 1, Indication of case Patent application No. 57-8467 3
, To Hitoshi Katayama, representative of the person making the amendment, Part 5, Detailed explanation of statement 1 () 1 of the amended specification 6, Contents of the amendment (1) M VI: (7) Page 2 No. 4 lines r/IN
v−jM−fB j is [f MV”””f M
+f S'J and K] Correct. (2) 2-0, line 5'/Inv"fM 10fsJ
``/INV''/ M ' f S J
jzHv-Nxf□ J is 'bNV'=N
'10 J and gJ pressure respectively. that's all

Claims (1)

【特許請求の範囲】[Claims] 誘導電動機を可変速運転する場合において、電源の可制
御の出力周波数が上記誘導電動機によって駆動される機
械系の固有振動数もしくはその整数倍と一致する周波数
帯域にある場合、上記誘導電動機を、必要トルクに対し
て該誘導電動機の特性から定まるすべや周波数よシ大で
あるすべり周波数で運転することを特徴とする誘導電動
機の運転方法。When operating an induction motor at variable speed, if the controllable output frequency of the power supply is in a frequency band that matches the natural frequency of the mechanical system driven by the induction motor or an integral multiple thereof, the induction motor is operated as necessary. A method of operating an induction motor, comprising operating the induction motor at a slip frequency that is larger than a slip frequency determined from the characteristics of the induction motor with respect to torque.