JP3045633B2 - Current power supply for electromagnet - Google Patents
Current power supply for electromagnetInfo
- Publication number
- JP3045633B2 JP3045633B2 JP6056028A JP5602894A JP3045633B2 JP 3045633 B2 JP3045633 B2 JP 3045633B2 JP 6056028 A JP6056028 A JP 6056028A JP 5602894 A JP5602894 A JP 5602894A JP 3045633 B2 JP3045633 B2 JP 3045633B2
- Authority
- JP
- Japan
- Prior art keywords
- power supply
- current
- voltage
- fet
- magnetic field
- 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
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- Electron Tubes For Measurement (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は質量分析装置等に使用さ
れている電磁石用電流電源に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current source for an electromagnet used in a mass spectrometer or the like.
【０００２】[0002]
【従来の技術】質量分析装置等に使用されている電磁石
用電流電源は、従来、図６に示すような回路が用いられ
ている。この電磁石用電流電源回路は定電圧の直流電源
１、磁場コイル２、電界効果トランジスタ（ＦＥＴ）
３、電流検出抵抗４を直列に接続した構成からなってお
り、基準信号源５からの掃引信号によりＦＥＴ３のイン
ピーダンスを制御し、基準信号に比例した電流を磁場コ
イル２に流して磁場を発生させるものである。磁場コイ
ル２に流れる電流は電流検出抵抗４で検出し、電流検出
増幅器７で増幅して誤差増幅器６にフィードバックし、
ＦＥＴを制御することにより基準信号源５の掃引信号に
比例した磁場を発生させている。なお、ツェナーダイオ
ード８は電流をＯＦＦした時の磁場コイル２に発生する
逆起電力を吸収するためのもである。2. Description of the Related Art Conventionally, a circuit as shown in FIG. 6 is used as a current power supply for an electromagnet used in a mass spectrometer or the like. This electromagnet current power supply circuit has a constant voltage DC power supply 1, a magnetic field coil 2, a field effect transistor (FET).
3, a current detection resistor 4 is connected in series, the impedance of the FET 3 is controlled by a sweep signal from a reference signal source 5, and a current proportional to the reference signal is supplied to the magnetic field coil 2 to generate a magnetic field. Things. The current flowing through the magnetic field coil 2 is detected by the current detection resistor 4, amplified by the current detection amplifier 7 and fed back to the error amplifier 6,
By controlling the FET, a magnetic field proportional to the sweep signal of the reference signal source 5 is generated. The zener diode 8 is for absorbing the back electromotive force generated in the magnetic field coil 2 when the current is turned off.
【０００３】いま、磁場コイル２のインダクタンス成分
をＬ、抵抗成分をＲ、電流検出抵抗４の抵抗をＲｄ、直
流電源４の電圧をＶ、ＦＥＴ３のドレイン・ソース間抵
抗をＲｍ、回路に流れる電流をｉとすると、 Ｖ＝Ｌ・ｄｉ／ｄｔ＋（Ｒ＋Ｒｄ＋Ｒｍ）・ｉ ……（１） が成立する。基準信号源５の掃引信号を図７（ａ）のよ
うに鋸歯状に変化させたとすると、磁場コイル２に流れ
る電流は図７（ｃ）のように変化し、ＦＥＴ３のドレイ
ン・ソース間電圧（Ｒｍ・ｉ）は図７（ｂ）のように変
化する。すなわち、基準信号源５からの信号が０の時に
はＦＥＴ３のドレイン・ソース間電圧は直流電源１の電
圧Ｖであり、基準信号が出力されると掃引速度に比例し
た逆起電力が磁場コイル２に発生するため、ドレイン・
ソース間電圧はその分だけ降下し、さらに抵抗による電
圧ドロップ分だけ基準信号に同期して降下していく。基
準信号がＯＦＦになると、その瞬間に磁場コイル２に直
流電源１と同極性の電圧が発生し、その大きさはツェナ
ーダイオード電圧ＶZDに抑えられるので、ドレイン・ソ
ース間電圧はＶZDとなる。以後、掃引基準信号の繰り返
し波形に同期してドレイン・ソース間電圧は変化し、励
磁電流が制御されることになる。Now, the inductance component of the magnetic field coil 2 is L, the resistance component is R, the resistance of the current detection resistor 4 is Rd, the voltage of the DC power supply 4 is V, the drain-source resistance of the FET 3 is Rm, and the current flowing through the circuit is Is i, V = Ldi / dt + (R + Rd + Rm) i (1) holds. Assuming that the sweep signal of the reference signal source 5 is changed in a sawtooth shape as shown in FIG. 7A, the current flowing through the magnetic field coil 2 changes as shown in FIG. 7C, and the drain-source voltage ( Rm · i) changes as shown in FIG. That is, when the signal from the reference signal source 5 is 0, the voltage between the drain and source of the FET 3 is the voltage V of the DC power supply 1, and when the reference signal is output, a back electromotive force proportional to the sweep speed is applied to the magnetic field coil 2. Because of the drain
The source-to-source voltage drops by that amount, and further drops by the voltage drop due to the resistance in synchronization with the reference signal. When the reference signal is turned off, a voltage having the same polarity as that of the DC power supply 1 is generated in the magnetic field coil 2 at that moment, and the magnitude thereof is suppressed to the Zener diode voltage V ZD , so that the drain-source voltage becomes V ZD. . Thereafter, the drain-source voltage changes in synchronization with the repetitive waveform of the sweep reference signal, and the exciting current is controlled.
【０００４】[0004]
【発明が解決しようとする課題】ところで図６に示した
回路において、ＦＥＴ３で消費される電力はドレイン・
ソース間電圧とそこに流れる電流（励磁電流と同じ）を
掛け合わせた値となる。質量分析装置に用いる磁場コイ
ル電流は５０Ａ、直流電源は２００Ｖ程度であるため、
ＦＥＴでの消費電力は数千Ｗ位の規模となり、そのた
め、ＦＥＴを冷却するために大きな水冷装置が必要とな
る。本発明は上記課題を解決するためのもので、電流制
御素子における消費電力を大幅に減少させることがで
き、冷却装置を小型化することができる電磁石用電流電
源を提供することを目的とする。In the circuit shown in FIG. 6, the power consumed by the FET 3 is equal to the drain current.
The value is obtained by multiplying the source-to-source voltage by the current flowing therethrough (the same as the exciting current). Since the magnetic field coil current used for the mass spectrometer is about 50 A and the DC power supply is about 200 V,
The power consumption of the FET is on the order of thousands of watts, so that a large water cooling device is required to cool the FET. An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a current power supply for an electromagnet that can significantly reduce power consumption in a current control element and can reduce the size of a cooling device.
【０００５】[0005]
【課題を解決するための手段】本発明は、直流電源に電
磁石および電流制御素子を直列に接続し、誤差増幅器へ
の入力信号である掃引基準信号により電流制御素子のイ
ンピーダンスを変化させて電磁石の励磁電流を変化さ
せ、該励磁電流を検出して前記誤差増幅器に帰還し、誤
差増幅器出力で電流制御素子を制御するようにした電源
であって、前記励磁電流の変化に合わせて前記直流電源
を制御する制御回路を設けたことを特徴とする。According to the present invention, an electromagnet and a current control element are connected in series to a DC power supply, and the impedance of the current control element is changed by changing the impedance of the current control element by a sweep reference signal which is an input signal to an error amplifier. A power source that changes an exciting current, detects the exciting current, feeds back the error current to the error amplifier, and controls the current control element with the output of the error amplifier. A control circuit for controlling is provided.
【０００６】[0006]
【作用】本発明は励磁電流の変化に合わせて励磁回路に
挿入されている直流電源を制御することにより、電流制
御素子に掛かる電圧を小さくして電流制御素子における
消費電力を大幅に少なくすることができる。According to the present invention, the voltage applied to the current control element is reduced by controlling the DC power supply inserted in the excitation circuit in accordance with the change in the excitation current, thereby greatly reducing the power consumption in the current control element. Can be.
【０００７】[0007]
【実施例】図１は本発明の電磁石用電流電源の基本回路
を示す図であり、１０はコントロール回路、１１はスイ
ッチング電源である。本発明においては、掃引信号に同
期させてコントロール回路１０でスイッチング電源１１
を制御し、電流制御素子であるＦＥＴ３を動作させるの
に必要最小限な電圧を発生させることにより、ＦＥＴに
おける消費電力を極力小さくするようにしたものであ
る。1 is a diagram showing a basic circuit of a current power supply for an electromagnet according to the present invention, wherein 10 is a control circuit, and 11 is a switching power supply. In the present invention, the switching power supply 11 is controlled by the control circuit 10 in synchronization with the sweep signal.
To generate the minimum voltage required to operate the FET 3 as a current control element, thereby minimizing power consumption in the FET.
【０００８】図２は図１の１具体例で、コントロール回
路１０を微分器１２、増幅器１３、加算器１４、オフセ
ット電圧発生器１５で構成している。次に、図２の動作
を図３の波形図を参照して説明する。基準信号源５から
発生する信号を図３（ａ）に示すような鋸歯状の掃引波
形としたとき、可変電圧電源、直流電源１の電圧が一定
であれば磁場コイル２、ＦＥＴ３、可変電圧直流電源
１、電流検出抵抗４で構成される回路は従来技術で説明
した（１）式のような形で動作し、ＦＥＴ３の消費電力
はＲｍ×ｉ×ｉとなる。ここで、可変電圧直流電源１を
磁場コイル２の電流の状態に応じて変化させ、ＦＥＴ３
のドレイン・ソース間電圧があまり大きな電圧にならな
いように制御すればＦＥＴ３での消費電力を軽減するこ
とができる。いま、図３（ａ）のような掃引信号を用い
たとき、可変直流電圧電源１を（２）式で示す電圧で制
御する。FIG. 2 is a specific example of FIG. 1, and the control circuit 10 comprises a differentiator 12, an amplifier 13, an adder 14, and an offset voltage generator 15. Next, the operation of FIG. 2 will be described with reference to the waveform diagram of FIG. When the signal generated from the reference signal source 5 has a sawtooth sweep waveform as shown in FIG. 3A, if the voltage of the variable voltage power supply and the DC power supply 1 is constant, the magnetic field coil 2, the FET 3, the variable voltage DC The circuit composed of the power supply 1 and the current detection resistor 4 operates in the form of the equation (1) described in the related art, and the power consumption of the FET 3 is Rm × i × i. Here, the variable voltage DC power supply 1 is changed in accordance with the state of the current of the magnetic field coil 2 and the FET 3
If the drain-source voltage is controlled so as not to be too large, the power consumption of the FET 3 can be reduced. Now, when a sweep signal as shown in FIG. 3A is used, the variable DC voltage power supply 1 is controlled by the voltage shown by the equation (2).
【０００９】 Ｖ＝Ｌ・ｄｉ／ｄｔ＋（Ｒ＋Ｒｄ）・ｉ＋Ｖ0 ……（２） （２）式の第１項は磁場コイル２に発生する逆起電力
分、第２項は磁場コイルと電流検出抵抗の抵抗による電
圧降下分、第３項はＦＥＴを動作させるのに最小限必要
なドレイン・ソース間電圧であり、第３項の電圧によっ
て発生する電力がＶ0 ・ｉとしてＦＥＴ３で消費される
ことになる。本実施例では、磁場コイルのインダクタン
ス成分で発生する逆起電力Ｌ・ｄｉ／ｄｔ成分を微分器
１２で、抵抗成分で発生する電圧（Ｒ＋Ｒｄ）・ｉを増
幅器１３で作り、Ｖ0 に対応するオフセット電圧１５と
共にこれらを加算器１４で合成して（２）式で示す電圧
を生成し、可変電圧直流電源１を制御する。このとき、
可変電圧直流電源１の出力電圧は図３（ｂ）に示すよう
になり、その結果、磁場コイル電流が増加しているとき
に磁場コイルのインダクタンス成分で発生する逆起電
力、磁場コイルと電流検出抵抗の抵抗による電圧降下分
がキャンセルされてドレイン・ソース間電圧は図３
（ｃ）に示す必要最小限の電圧となり、磁場コイル電流
が減少するときはツェナー電圧ＶZDとなり、ドレイン・
ソース間電圧を大幅に減らすことができ、そのためＦＥ
Ｔの消費電力を大幅に減少させることができる。V = L · di / dt + (R + Rd) · i + V 0 (2) The first term of the equation (2) is the amount of back electromotive force generated in the magnetic field coil 2, and the second term is the magnetic field coil and current detection The third term is the minimum drain-source voltage required to operate the FET, and the power generated by the voltage of the third term is consumed by the FET 3 as V 0 · i by the voltage drop due to the resistance of the resistor. Will be. In this embodiment, the back electromotive force L · di / dt component generated by the inductance component of the magnetic field coil is generated by the differentiator 12, and the voltage (R + Rd) · i generated by the resistance component is generated by the amplifier 13, and corresponds to V 0 . These are combined with the offset voltage 15 by the adder 14 to generate a voltage represented by the expression (2), and the variable voltage DC power supply 1 is controlled. At this time,
The output voltage of the variable voltage DC power supply 1 is as shown in FIG. 3 (b). As a result, when the magnetic field coil current increases, the back electromotive force generated by the inductance component of the magnetic field coil, the magnetic field coil and the current detection The voltage drop due to the resistance of the resistor is canceled, and the drain-source voltage is reduced as shown in FIG.
Required minimum voltage (c), the Zener voltage V ZD becomes when the magnetic field coil current decreases, the drain-
The source-to-source voltage can be greatly reduced, so that FE
The power consumption of T can be greatly reduced.
【００１０】図４は従来の電磁石用電流電源のＦＥＴに
おける消費電力を示すもので、電源電圧一定値、基準信
号源における掃引電圧を図のように発生したときの励磁
電流ＦＥＴのパワーロスを示している。図５は本発明に
よるＦＥＴパワーロスを示し、電源電圧を前述したよう
に励磁電流の変化に応じてコントロールしており、図４
の場合に比してＦＥＴのパワーロスを大幅に減少できて
いることが分かる。FIG. 4 shows the power consumption of the FET of the conventional electromagnet current power supply, and shows the power loss of the excitation current FET when the power supply voltage is constant and the sweep voltage in the reference signal source is generated as shown in FIG. I have. FIG. 5 shows the FET power loss according to the present invention, in which the power supply voltage is controlled according to the change in the exciting current as described above.
It can be seen that the power loss of the FET has been significantly reduced as compared to the case of (1).
【００１１】なお、図２に示した電源回路においては、
可変電圧直流電源の制御を微分器、増幅器、加算器、オ
フセット電圧で生成するようにしたが、これに限らず、
このコントロールはコンピュータ等の演算処理装置を用
いて、演算・出力しても良く、また、ＦＥＴの代わりに
トランジスタ、ＩＧＢＴ、ＳＩＴ等の電流制御素子を用
いても良く、また磁場検出に用いる電流検出抵抗の代わ
りにホール素子等の磁場計測用のセンサを用いることも
可能である。In the power supply circuit shown in FIG. 2,
The control of the variable voltage DC power supply is generated by the differentiator, the amplifier, the adder, and the offset voltage.
This control may be calculated and output using an arithmetic processing device such as a computer. A current control element such as a transistor, IGBT, or SIT may be used instead of the FET. It is also possible to use a sensor for measuring a magnetic field such as a Hall element instead of the resistance.
【００１２】[0012]
【発明の効果】以上のように本発明によれば、磁場コイ
ルに流れる電流に合わせて直流電源をコントロールする
ことにより電流制御素子にかかる電圧を小さくし、消費
電力を大幅に軽減し、その結果電流制御素子を冷却する
ための装置を小型化することが可能となる。As described above, according to the present invention, the voltage applied to the current control element is reduced by controlling the DC power supply in accordance with the current flowing through the magnetic field coil, and the power consumption is greatly reduced. It is possible to reduce the size of the device for cooling the current control element.
【図面の簡単な説明】[Brief description of the drawings]
【図１】 本発明の電磁石用電流電源の基本回路を示す
図である。FIG. 1 is a diagram showing a basic circuit of a current power supply for an electromagnet of the present invention.
【図２】 図１の１具体例を示す図である。FIG. 2 is a diagram showing a specific example of FIG.
【図３】 図２の動作の波形図である。FIG. 3 is a waveform chart of the operation of FIG. 2;
【図４】 従来の電源回路のＦＥＴにおける消費電力を
示す図である。FIG. 4 is a diagram showing power consumption in an FET of a conventional power supply circuit.
【図５】 本発明によるＦＥＴパワーロスを示す図であ
る。FIG. 5 is a diagram showing FET power loss according to the present invention.
【図６】 従来の電磁石用電流電源回路を示す図であ
る。FIG. 6 is a diagram showing a conventional electromagnet current power supply circuit.
【図７】 図６の回路における波形図である。FIG. 7 is a waveform chart in the circuit of FIG. 6;
１…直流電源、２…磁場コイル、３…電界効果トランジ
スタ（ＦＥＴ）、４…電流検出抵抗、５…基準信号源、
６…誤差アンプ、７…電流検出増幅器、８…ツェナーダ
イオード、１０…コントロール回路、１１…スイッチン
グ電源。REFERENCE SIGNS LIST 1 DC power supply 2 magnetic field coil 3 field effect transistor (FET) 4 current detection resistor 5 reference signal source
6 Error amplifier, 7 Current detection amplifier, 8 Zener diode, 10 Control circuit, 11 Switching power supply.
Claims (1)
直列に接続し、誤差増幅器への入力信号である掃引基準
信号により電流制御素子のインピーダンスを変化させて
電磁石の励磁電流を変化させ、該励磁電流を検出して前
記誤差増幅器に帰還し、誤差増幅器出力で電流制御素子
を制御するようにした電源であって、前記励磁電流の変
化に合わせて前記直流電源を制御する制御回路を設けた
ことを特徴とする電磁石用電流電源。An electromagnet and a current control element are connected in series to a DC power supply, and the excitation current of the electromagnet is changed by changing the impedance of the current control element by a sweep reference signal which is an input signal to an error amplifier. A power supply which detects a current and feeds back to the error amplifier, and controls a current control element with an output of the error amplifier, wherein a control circuit for controlling the DC power supply in accordance with a change in the exciting current is provided. A current power supply for electromagnets.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6056028A JP3045633B2 (en) | 1994-03-25 | 1994-03-25 | Current power supply for electromagnet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6056028A JP3045633B2 (en) | 1994-03-25 | 1994-03-25 | Current power supply for electromagnet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07263227A JPH07263227A (en) | 1995-10-13 |
| JP3045633B2 true JP3045633B2 (en) | 2000-05-29 |
Family
ID=13015619
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6056028A Expired - Lifetime JP3045633B2 (en) | 1994-03-25 | 1994-03-25 | Current power supply for electromagnet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3045633B2 (en) |
-
1994
- 1994-03-25 JP JP6056028A patent/JP3045633B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07263227A (en) | 1995-10-13 |
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