JPH04205509A - Power unit and particle accelerator using said power unit - Google Patents

Abstract

PURPOSE:To prevent the change of the output current of a current amplifier circuit despite the change of an output current and to attain a compact power unit by detecting the output current of the amplifier which generates the pulsating voltage having a phase opposite to that of the pulsating voltage of a main circuit and negatively feeding back the detected output current. CONSTITUTION:A high-pass filter 13 extracts a pulsating component out of the voltage detected by a voltage detector 11. An amplifier 16 supplies an exciting current to a reactor 18 to generate the pulsating voltage having a phase opposite to the pulsating voltage of a main circuit which is induced at the reactor 18 with the integrated value of an extracted pulsating component. Then a current of an adverse phase flows in the reactor 18 in accordance with the pulsating component by the function of the amplifier 16 and the pulsating component applied to the main circuit can be eliminated. Furthermore the output current is kept at a level accordant with the pulsating component by the negative feedback circuits 15 and 17 even though an overcurrent is to flow in the amplifier 16 from the reactor 18. As a result, the capacity of the amplifier 16 can be reduced and also the breakage of the amplifier 16 can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power supply device using an active filter, and particularly to an electromagnet that requires high precision and high-speed controllability, such as the main electromagnet of a synchrotron particle accelerator. The present invention relates to a power supply device suitable for applications such as the above.

[Prior Art] In synchrotron particle accelerators, electromagnets are used to control the orbits of particles.

In such a particle accelerator, deviations in the trajectory of particles with large kinetic energy are not allowed, so
The direct current that excites the electromagnet does not contain pulsating current and is required to have high stability. Hitachi Hyoron (Vo163-6, p397-400 1933
Published in June 2016, Haka Shintomi “DC Active Filter”)
JP-A-61-150018 discloses a power supply device in which a reactor-transformer coupled active filter as shown in FIG.

[Problems to be Solved by the Invention] In the above-mentioned prior art, the output section of the active filter is magnetically coupled to the power supply main circuit by a reactor transformer. When the output current of the power supply unit that excites the main electromagnet is suddenly increased or decreased in order to change the strength of the magnetic field of the main electromagnet of the particle accelerator, the magnetic coupling of the reactor transformer causes thousands of waves to be generated on the amplifier side of the active filter. A current change occurs that is about the same as the main circuit current of amperes but differs by the turns ratio of the reactor transformer, and an amplifier that can withstand this current change is required to have an excessive output capacity.

Furthermore, since the function of the active filter is to suppress pulsations in the output voltage, or in other words, changes in the output voltage, it is not suitable for applications in which the output of the power supply is to be changed at high speed. That is, when an attempt is made to change the output voltage through a control operation, the active filter detects the voltage change and operates to suppress it.

As a means to solve this problem,
As shown in Japanese Patent No. 18, a method has been considered in which the control operation signal is converted into an output voltage and subtracted from the voltage detection section of the active filter.

However, when this measure is taken and applied to applications in which the output current is to be changed suddenly, there is a problem in that the control operation is delayed, making it impossible to realize a power supply device such as an accelerator that requires high precision and high-speed controllability.

An object of the present invention is to reduce the output capacitance of an amplifier of an active filter.

In addition to the above objects, another object of the present invention is to provide a highly accurate power supply device capable of high-speed response and a particle accelerator using the same.

[Means for Solving the Problems] The above object is to provide a conversion device that has a switching element and converts alternating current to direct current and outputs it, a passive filter connected to the output of the conversion device, and a passive filter of the passive filter. A power supply comprising an active filter connected to an output and a conversion device control circuit that controls a switching element of the conversion device according to a current command, and configured to supply the output of the active filter to a load. In the device, the active filter includes a reactor inserted in series in a DC main circuit, a voltage detector that detects a high voltage of the passive filter, and a high-pass filter that extracts a ripple component from the detected voltage. , an integrating circuit that outputs a filter control command obtained by performing at least an integral process on the extracted pulsating flow component; and a pulsating current voltage that is in opposite phase to the main circuit pulsating voltage induced in the reactor in response to the filter control command. and a negative feedback circuit that detects the output current of the amplifier and negatively feeds back the detected current to the filter control command. This is achieved by

The purpose of the above function is to obtain a current operation amount that causes the converter control circuit to match the load current of the converter with a given current command, and to control the switching element based on the current operation amount. This is achieved by providing an adder that subtracts a voltage corresponding to the current operation amount of the converter control circuit from the detected voltage of the output voltage of the passive filter, and inputting the output of the adder to the high-pass filter. Ru.

The power supply device having the above configuration includes a particle generator that generates particles;
A pre-stage accelerator that accelerates the particles generated by the particle generator to a predetermined energy level, and a final stage accelerator that accelerates the particles accelerated by the pre-stage accelerator using a high-frequency acceleration cavity while circulating them with a main electromagnet to impart predetermined particle energy. By applying the present invention to a particle accelerator equipped with a stage accelerator and using it as a power supply device that excites the main electromagnet, the orbit of the particles can be maintained accurately and the particles can be stably accelerated to a predetermined energy level in a short time. A particle accelerator can be realized.

[Operation] According to the above configuration, a current having an opposite phase in accordance with the pulsating current component flows through the reactor due to the action of the amplifier, and a voltage is thereby induced, so that the pulsating current component flowing through the main circuit is removed.

Moreover, since the negative feedback circuit is provided, even if an excessive current attempts to flow from the chictor to the amplifier side, the output current of the amplifier is maintained at a current corresponding to the pulsating current component. In this way, the capacity of the amplifier can be reduced and damage can be prevented.

In addition, when the output current is suddenly changed by a current command, a signal corresponding to the current operation amount is subtracted from the detected value of the high voltage of the passive filter to remove the influence of the change in the output current that appears in the pulsating flow component. Therefore, the voltage induced in the reactor is not affected by it, and the current in the main circuit quickly follows the current command, making high-speed control possible.

Furthermore, by supplying pure direct current excitation current to the main electromagnet of the synchrotron particle accelerator from the power supply device with the above-mentioned configuration, which has the characteristics of changing the current with high precision and high speed, the orbit of the particles can be maintained accurately and shortened. Particles can be stably accelerated to a predetermined energy level over time.

[Example 1] An example of the present invention will be described below with reference to FIG. 1st
The figure is a block diagram showing the configuration of a power supply device that supplies direct current to the load device 7. As shown in FIG.

First, the configuration of the power supply device will be explained. The power supply device controls a thyristor conversion device 2 that converts alternating current power into direct current, a passive filter 3 connected to the output of this thyristor conversion device 2, an active filter 1 and thyristor conversion device 2 connected to the output of this passive filter 3. It is composed of a converter control circuit 10.

The converter control circuit 10 includes a constant current controller 4 that operates based on a current control command 9, a constant voltage controller 5, and an automatic pulse phase shifter 6 that outputs a manipulated variable to the thyristor of the thyristor converter 2. ing.

The passive filter 3 is composed of a DC inductor, a capacitor, and the like. The active filter 1 includes a reactor transformer 18 inserted into the main DC circuit, an amplifier 16 that supplies an exciting current to this secondary winding, a voltage detector 11 that detects the output voltage of the passive filter 3, and the detected voltage. an adder 12 for determining the deviation of the control signal Vc from the converter control circuit 10;
A high-pass filter 13 which inputs the output of the adder 12 and passes only the pulsations contained in the high-voltage of the passive filter 3, an integrator 14 which integrates the output of this high-pass filter 13, and an integrator 1.
4 and the current feedback value obtained by the current detector 17 that detects the output current of the amplifier 16. Next, the operation of the power supply device will be explained. do.

The converter control circuit 10 subtracts the feedback current signal detected by the DC current detector 8 from the current control command 9 using the first adder 21, and controls the current to be constant using the constant current controller 4, thereby performing constant current control. The output of the converter 4 and the detected value of the output voltage of the thyristor conversion device 2 are inputted to the second adder 23 to determine the voltage operation amount, and the voltage is input to the thyristor conversion device via the constant voltage controller 5 and the automatic pulse phase shifter 6. Controls the output of 2.

The output voltage of the thyristor conversion device 2 is input to the active filter 1 after the pulsation of the output voltage is reduced by the passive filter 3 . A voltage detector 11 detects the output voltage of the passive filter 3, and a high-pass filter 13 extracts an alternating current component of the detected voltage from the detected voltage. This AC component is converted into an integrator 14.
Perform an integral calculation to obtain the current setting value. The amplifier 16 is driven at a constant current according to the current setting value. The output current of the amplifier 16 is detected by a current detector 17, subtracted from the current setting value by an adder 15, and negative feedback amplified, thereby driving the amplifier 16 at a constant current. The output current of the amplifier 16 is supplied to the reactor transformer 18 in opposite phase, and the reactor transformer 18
The passive filter 3 operates to cancel the pulsating current contained in the output voltage by the combination of the passive filter 3 and the passive filter 3. That is, the output current of the amplifier 16 is set to 1, and this current causes the reactor transformer 18 to
If the voltage induced in the primary winding of is Va, then Va is (
1) It is expressed by the formula. Here, M is the mutual inductance d of the reactor transformer 18, so that i becomes a differential waveform and the output of the high-pass filter 13 differs from V.

When the detected voltage is Vd10V (Vd is the DC voltage, ■ is the pulsating voltage), the output of the high-pass filter 13 is only V, and when the output V of the high-pass filter 13 is integrated, the output current 1 is (2) It is expressed by the formula.

i=□・・・・・・・・・・・・・・・・・・・・・
(2) where ■: pulsating voltage T: integration time S Nira plus operator.

The amplifier 16 and subsequent parts are controlled to be equal to the output of the integrator 14, and if the mutual inductance of the reactor transformer 18 is M, a voltage Va expressed by equation (3) is generated on the output side of the reactor transformer 18. .

Va=s-M-i・・・・・・・・・・・・・・・
・・・・・・・・・(3)=□・V・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・(4) Now, T=M−・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・(5) and substituting equation (5) into equation (4), Va=v and the output voltage E of the power supply
d is Ed=(Vd+v)-Va=Vd・・・・・・・・・・・・・・・・・・・
It becomes a river (6) and the pulsating voltage is canceled out.

A case where a control operation based on a current control command is performed will be explained with reference to FIG. When the current control command 9 changes, the control signal Vc output from the constant current controller 4 changes as shown in FIG. 2(a). Similarly, the output voltage Vd of the passive filter 3 has an ideal pattern (equal to the control signal Vc) as shown in FIG.
) as shown in the dotted line, but in reality, the pulsating voltage ■ is superimposed and becomes Vd+V, and the response is further delayed as shown in the solid line due to the influence of filters and the like. The output of the adder 12 has the waveform shown in FIG. 2(c). The output of the high-pass filter 13 is shown in Figure 2(d).
This results in the waveform shown in . Note that when the control signal Vc is not subtracted, the result looks like the dotted line in the figure. When the output of the high-pass filter 13 is input to the integrator 14 and integrated, the waveform becomes as shown in FIG. 2(e), and when the control signal Vc is not subtracted, the waveform becomes like the dotted line.

The output of the integrator 14 is input to the amplifier 16, and its output current is detected by the current detector 17, subtracted from the output of the integrator 14 by the adder 15, and feedback amplified.
It is controlled so that there is no deviation from the output of 4. Therefore, its waveform is equal to the output of the integrator 14 as shown in the sixth stage. The output current of the amplifier 16 is supplied to a reactor transformer 18, and on the secondary side there is a voltage Va having a differential waveform of the output current of the amplifier 16, that is, a seventh voltage equal to the output of the high-pass filter 13 before being integrated by the integrator 14. The waveform shown in the column appears.

On the secondary side of the reactor transformer 18, E d = (V
d + v ) -V a -------= -(7), the waveform shown in the 8th stage appears, and the change in control signal Vc also becomes Va = v - Vc, which is output to Va and output from the power supply. The voltage is Ed=Vd+Vc・・・・・・・・・・・・・・・・・・
(8) By subtracting Vc, the output voltage responds immediately and the control operation can be output immediately.

If there is no row for subtracting Vc, the waveform will look like the dotted line, and the response will be slow.

In reality, the integrator 14 is replaced by a pseudo-integrator circuit such as a first-order delay circuit so that the control offset amount is not integrated. When the time constant of the first-order lag is τ, the gain is K, and the characteristic of the first-order lag is /(1+τS), then T=□・M・・・・・・・・・・・・・・・・・・・・・
If τ and K are determined so that (9) is obtained, τ
The same characteristics as above can be achieved within the range of s))1.

By performing advance compensation as follows, it is possible to improve the deterioration of characteristics in the high frequency range due to iron loss. That is, when the iron loss frame is represented by a resistor R8 in parallel with M, the voltage generated on the output side of the reactor transformer 18 due to the output current i of the amplifier 16 is τ, =□...・・・・・・・・・・・・・・・
By setting (11), Va#v can be obtained.

FIG. 3 shows an example in which the reactor transformer 18 in FIG. 1 is replaced with a DC inductor 19, but the converter control circuit 10 is omitted to simplify the diagram. Here, the same reference numerals as in FIG. 1 indicate the same products. If the inductance of the DC inductor 19 is R, and the resistance is R, the voltage Va induced across the DC inductor 19 is Va = (s-L+R)v ---(12)l+τ・
It becomes S.

τ＝□・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・(13)＝□・・・・・・・・・・
By setting ・・・・・・・・・・・・・・・・・・・・・(14), Va=v・・・・・・・・・・・・・・・・・・・・・
......(15). According to this embodiment, complete compensation can be achieved even if the integrator 14 has pseudo-integral characteristics.

In the example shown in FIG. 4, the control operation amount Vc is passed through a filter 20 with a transfer function G(s) and subtracted from the input of the active filter. The characteristics of the transfer function G(s) are determined by the voltage control delay of the thyristor converter 2 and the passive filter 3.
We will respond to any delays. According to this embodiment, Vc'=G(s)·Vc--(16) can be made approximately equal to Vd. Therefore, the input voltage of the high-pass filter 13 is (Vd + v) - Vc' = v - - - - - (17
), and is mostly just a pulsating voltage. According to this embodiment, even if a control operation is performed, the amplifier 16 does not need to output the amount of change due to the control operation, and there is an effect that there is almost no increase in output capacity.

In this embodiment, furthermore, the manipulated variable V by feedforward
This shows the case where f is added to the control signal Vc, and is disclosed in Japanese Patent Application Laid-open No. 6
Feedforward control as shown in Japanese Patent No. 2-191905 is also possible.

In the embodiment shown in FIG. 5, the feedforward manipulated variable Vf is used for control via a filter 20 with a transmission interval G(s). According to this embodiment, due to the feature of feedforward that the feedforward operation can be performed taking into account the delay in the transfer function G(s), it is possible to perform an operation that compensates for the delay in the transfer function G(s). It is. On the other hand, regarding the feedback operation, the transfer function G(s
) Since there is no delay, control becomes faster. Generally, feedforward is necessary when attempting to change the output significantly, so passing the transfer function G(s) has a large effect of reducing the amplifier output capacitance.

Moreover, as mentioned above, there is an effect that high-speed control is maintained.

Next, an embodiment will be described in which the power supply device according to the present invention is used as a power supply for exciting an electromagnet of a synchrotron particle accelerator.

First, the overall configuration of a proton synchrotron, which is a typical synchrotron particle accelerator, will be explained.

Protons (hydrogen ions) generated by discharge in the proton generator are accelerated by high voltage in the first stage accelerator, further accelerated by a booster in the linear accelerator, and then transferred to the final stage accelerator (main ring).
The particles are sent to the particle, are accelerated while rotating, and are given a predetermined particle energy. The final stage accelerator has a circular orbit, and a main electromagnet and a high-frequency acceleration cavity are arranged on the orbit. The main electromagnet is composed of a deflecting electromagnet that deflects protons so that they orbit in a circumferential orbit, and a focusing quadrupole electromagnet and a diverging quadrupole electromagnet that focus the proton beam so that it does not deviate from its orbit. A power supply device for DC exciting each electromagnet is also arranged. Since this power supply device has a large output and rapidly changes and repeats the load current and voltage in a fixed pattern, it is required to have high accuracy, high power factor, and high reliability. The high-frequency acceleration cavity is a device that accelerates protons using high-frequency waves, and the protons are gradually accelerated each time they pass through.

FIG. 6 shows a connection between an electromagnet of a proton synchrotron and a power supply device according to the present invention that excites the electromagnet.

The bending electromagnet excitation power source 31 is a power source for exciting the bending electromagnet 34, and the focusing electromagnet excitation power source 32 is a power source for exciting the focusing quadrupole electromagnet 3.
It is a power source for exciting the divergent quadrupole electromagnet excitation power source 33.
is a power source that excites the divergent quadrupole electromagnet 36.

Next, we will explain the acceleration of protons. When accelerating protons, the magnetic field generated by these electromagnets increases in accordance with the energy of the protons. For example, if the acceleration time is 1 second, the protons will be accelerated to a predetermined energy level from a magnetic field of about 10% corresponding to the low energy level protons at the beginning of acceleration when the protons are launched into the final stage accelerator. In order to rapidly change the magnetic field to 100% corresponding to protons in one second and to focus the proton beam so that it does not deviate from its orbit, it is necessary to control the magnetic field with a precision of 0.01% or more.

In order to supply an excitation current to such a magnetic field, a power supply device is required to have extremely high accuracy, suppress ripples, and change the current at high speed.

By using the power supply device according to the present invention in a synchrotron particle accelerator, the orbit of the particles can be maintained correctly, so that the particles can be stably accelerated to a predetermined energy level in a short time.

[Effects of the Invention] According to the present invention, since the current value calculation circuit is controlled so that the output current of the current amplifier circuit does not change even if the output current is changed, it is necessary to take into account damage to the amplifier due to excessive current. A compact amplifier can be obtained.

Further, when the output current is suddenly changed, the control operation amount is outputted to the active filter without passing through the passive filter as described above, so that high-speed control is possible.

Furthermore, by supplying excitation current to the main electromagnet of the synchrotron particle accelerator from a power supply device with the above configuration that has the characteristics of high precision, suppressing ripples, and changing the current at high speed, the orbit of the particles can be maintained correctly. The effect of stably accelerating particles to a predetermined energy level in a short period of time is obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG.
The figure is a waveform diagram explaining the control operation of the embodiment of the present invention.
5 to 5 are block diagrams showing the configuration of other embodiments of the present invention, and FIG. 6 is a block diagram showing the relationship between the electromagnet of the proton synchrotron according to the embodiment of the present invention and the power supply device that excites the electromagnet. 1... Active filter, 2... Thyristor conversion device, 3... Passive filter, 4... Constant current controller, 5...
...Constant voltage controller, 6...Automatic pulse phase shifter, 7...
- Load device, 9... Current control command, 10... Conversion device control circuit, 11... Voltage detector, 12.15...
Adder, I3...high-pass filter, 14...integrator,
16...Amplifier, 18...Current detector, 18...
Reactor transformer, 19... DC inductor, 20...
・・Operation delay filter, 21 ・・First adder, 23・
...Second adder, 31...Bending electromagnet excitation power supply, 32
...Focusing electromagnet excitation power supply,

Claims (1)

[Claims] 1. A conversion device having a switching element and converting alternating current into direct current and outputting it, a passive filter connected to the output of the conversion device, and a passive filter connected to the output of the passive filter. In a power supply device comprising an active filter and a conversion device control circuit that controls a switching element of the conversion device according to a current command, the power supply device is configured to supply an output of the active filter to a load. A type filter includes a reactor inserted in series in a DC main circuit, a voltage detector that detects the output voltage of the passive filter, a high-pass filter that extracts a ripple component from the detected voltage, and a high-pass filter that extracts a ripple component from the detected voltage. an integrating circuit that outputs a filter control command obtained by performing at least integral processing on a flow component; and an excitation current that generates a pulsating voltage having a phase opposite to the main circuit pulsating voltage induced in the reactor in accordance with the filter control command; A power supply device comprising: an amplifier that supplies the reactor; and a negative feedback circuit that detects an output current of the amplifier and provides negative feedback of the detected current to the filter control command. 2. The power supply device according to claim 1, wherein the reactor is a reactor transformer whose primary winding is inserted and connected to the DC main circuit, and whose secondary winding is connected to the output of the amplifier. A power supply device characterized in that it is connected to. 3. The power supply device according to claim 1, wherein the reactor is a DC inductor inserted and connected to the DC main circuit, and both ends of the DC inductor are connected to the output of the amplifier. power supply. 4. A conversion device that has a switching element and converts alternating current into direct current and outputs it, a passive filter connected to the output of the conversion device, an active filter connected to the output of the passive filter, and the a converter control circuit that determines a current manipulated amount that makes the load current of the converter match a given current command, and controls the switching element based on the current manipulated amount, and controls the output of the active filter as a load. In the power supply device, the active filter includes a reactor inserted in series with a DC main circuit, a voltage detector that detects the output voltage of the passive filter, and a voltage detector that detects the output voltage of the passive filter. A filter control comprising: an adder that subtracts a voltage corresponding to the current operation amount of the control circuit; a high-pass filter that extracts a pulsating flow component of the output of the adder; and a filter control that performs at least an integral process on the extracted pulsating flow component. an integrator circuit that outputs a command; an amplifier that supplies the reactor with an excitation current that generates a pulsating current voltage having an opposite phase to the main circuit pulsating voltage induced in the reactor in accordance with the filter control command; A power supply device comprising: a negative feedback circuit that detects an output current and feeds the detected current back to the filter control command. 5. The power supply device according to claim 4, wherein the reactor is a reactor transformer whose primary winding is inserted and connected to the DC main circuit, and whose secondary winding is connected to the output of the amplifier. A power supply device characterized in that it is connected to. 6. The power supply device according to claim 4, wherein the reactor is a DC inductor inserted and connected to the DC main circuit, and both ends of the DC inductor are connected to the output of the amplifier. power supply. 7. The power supply system according to any one of claims 4, 5, and 6, wherein the voltage corresponding to the current operation amount of the converter control circuit is applied to the adder via a delay circuit set to a predetermined delay time. A power supply device characterized in that the input power is input to the power source. 8. In the power supply device according to any one of claims 4, 5, and 6, a feedforward voltage command is added to the voltage corresponding to the current operation amount of the converter control circuit, and the added value or the feedforward voltage A power supply device characterized in that the voltage command is input to the adder via a delay circuit set to a predetermined delay time. 9. The power supply device according to claim 7 or 8, wherein the delay time of the delay circuit is set to a response delay time when a change in the current manipulated variable appears in the output voltage of the passive filter. power supply. 10. A particle generator that generates particles, a pre-accelerator that accelerates the particles generated by the particle generator to a predetermined energy level, and a high-frequency acceleration cavity that rotates the particles accelerated by the pre-accelerator using a main electromagnet. A particle accelerator comprising a final stage accelerator that accelerates and imparts predetermined particle energy, and a power supply device that excites the main electromagnet, wherein the power supply device has a switching element and converts alternating current to direct current and outputs it. a conversion device control circuit that controls a switching element of the conversion device according to a current command; a passive filter connected to the output of the conversion device; an active filter connected to the output of the passive filter; The active filter comprises a reactor inserted in series with the DC main circuit, a voltage detector that detects the output voltage of the passive filter, and a high-frequency detector that extracts a ripple component from the detected voltage. a filter, an integrating circuit that outputs a filter control command obtained by performing at least an integral process on the extracted pulsating flow component, and a pulsation that is in opposite phase to the main circuit pulsating voltage induced in the reactor in response to the filter control command; The present invention is characterized by comprising an amplifier that supplies an excitation current that generates a current voltage to the reactor, and a negative feedback circuit that detects the output current of the amplifier and negatively feeds the detected current back to the filter control command. particle accelerator. 11. A particle generator that generates particles, a pre-accelerator that accelerates the particles generated by the particle generator to a predetermined energy level, and a high-frequency acceleration cavity that rotates the particles accelerated by the pre-accelerator using a main electromagnet. A particle accelerator comprising a final stage accelerator that accelerates and imparts predetermined particle energy, and a power supply device that excites the main electromagnet, wherein the power supply device has a switching element and converts alternating current to direct current and outputs it. A device, a passive filter connected to the output of the converter, an active filter connected to the output of the passive filter, and a current control amount that makes the load current of the converter match a given current command. a converter control circuit for controlling the switching element based on the current operation amount, and the active filter includes a reactor inserted in series with the DC main circuit and an output voltage of the passive filter. a voltage detector for detecting; an adder for subtracting a voltage corresponding to the current operation amount of the converter control circuit from the detected voltage; a high-pass filter for extracting a pulsating flow component of the output of the adder; an integrating circuit that outputs a filter control command obtained by at least integrally processing the pulsating current component, and generating a pulsating voltage having an opposite phase to the main circuit pulsating voltage induced in the reactor in accordance with the filter control command; A particle accelerator comprising: an amplifier that supplies excitation current to the reactor; and a negative feedback circuit that detects the output current of the amplifier and feeds back the detected current negatively to the filter control command.