JP2008027360A - Control circuit - Google Patents

Abstract

A control circuit for stably controlling an output voltage of a power supply for an accelerator using an induced voltage regulator with high accuracy.
A control circuit 30b for an accelerator power supply apparatus using an induction voltage regulator 10 is provided for comparing a first reference voltage value having a predetermined difference with a set value and a voltage value of a DC voltage. Based on the output of the first comparator 32 and the first comparator 32, a control for outputting an ON control pulse to the induced voltage regulator 10 until the voltage value of the DC voltage becomes closer to the set value than the first reference voltage value. The gate is controlled according to the output of the pulse generation circuit 34 and the first comparator 32, and the second reference voltage value, which is closer to the set value than the first reference voltage value, is compared with the voltage value of the DC voltage. Short pulse generation for outputting a short pulse based on the output of the second comparator 36 to the induced voltage regulator 10 when the voltage value of the DC voltage is closer to the set value than the first reference voltage value. Circuit 38.
[Selection] Figure 1

Description

  The present invention relates to a control circuit that stably controls an output voltage of an accelerator power source using an induced voltage regulator with high accuracy.

  A motor driven induction voltage regulator (IVR) is usually used as a power source for an elementary particle accelerator used for medical and synchrotron radiation applications. As a method for controlling such a power supply device, the one shown in Patent Document 1 is known. The control circuit of the power supply device described in Patent Document 1 detects the output current of the power supply device with a current detector, and feeds back an operation amount that makes the deviation between the detected value and the current command value zero. Control is in progress.

  At that time, the control circuit detects the ambient temperature of the current detector by the temperature detector, estimates the gain error and offset error of the current detector by the error calculator based on the ambient temperature, and uses these estimated values. The current command value is corrected. In this way, highly accurate current control can be realized.

  Further, in Patent Document 2, there is a switch means for supplying a pulse voltage to the klystron by turning on / off the DC voltage. When this switch means is turned off, the detected value of the DC voltage immediately before being turned off is held, and when turning on again. A control circuit is described which switches the held DC voltage to a detected DC voltage.

  By using this control circuit, in the klystron power supply using an induction voltage regulator or a thyristor switch, it is possible to realize a pulse operation with a high accuracy of pulse amplitude.

  FIG. 3 is a block diagram showing a configuration of an accelerator power supply device including a conventional control circuit. A control circuit 30a, which is a conventional control circuit, includes a first comparator 32 and a control pulse generation circuit 34.

In this accelerator power supply device, the input voltage is amplified by an induction voltage regulator 10 with respect to a set value from the outside, and the output is rectified to a direct current by a rectifier circuit 14 via a transformer 12. Thereafter, the output voltage _VDC smoothed by the choke coil 16 passes through a charging circuit including a charging choke 18 and a hold-off diode 20 and is resonance-charged to a pulse shaping circuit (PFN) 22. The charge charged in the pulse shaping circuit 22 is discharged at once by a large capacity switch such as a thyratron (not shown) to form a large power pulse, and the charging voltage _VPFN is output to the klystron.

At this time, the DeQ circuit 24 performs input energy suppression control that keeps V _PFN constant. Here, the DeQ circuit is a De-Qing circuit, and is a circuit for forcibly stopping charging by decreasing the Q value of the resonant charging circuit when the charging voltage of the PFN 22 reaches a certain set value. . That is, it aims at keeping each pulse voltage applied to a klystron constant.

The voltage _VDC is fed back to the IVR 10 via the control circuit 30a (analog control or digital control).

In the control circuit 30a, the first comparator 32 compares the voltage _VDC with the reference voltage. The control pulse generation circuit 34 receives the output of the first comparator 32, generates a control pulse, and feeds it back to the IVR 10.

Next, the operation of the control circuit 30a described above will be described with reference to FIG. Here, a case where _VDC is lower than the set value will be described. At the time of t ₀ , which is the start time, when V _DC is lower than the set value by a predetermined difference (TS) (V _DC <V _ref — _{L 1} = set value−TS), the control pulse generation circuit 34 Based on the output of the first comparator 32, the control pulse CP is output to the IVR 10 and controlled. The IVR 10 is controlled by the motor so that the _VDC approaches the set value based on the control pulse. When V _DC exceeds the reference voltage V _{ref_L1} (t ₁ ), the control pulse generation circuit 34 stops the output.

Even when V _DC is higher than the set value, although not shown, V _DC is higher than the set value by a predetermined difference (TS) or more at the time t ₀ which is the start time (V _{In the case of DC} > V _{ref_H1} = set value + TS), the control pulse generation circuit 34 outputs a control pulse CP to the IVR 10 based on the output of the first comparator 32 and controls it.

Here, the IVR 10 has terminals on the UP side and the DOWN side, and the rotation direction of the motor is reversed between UP and DOWN. Therefore, when the _VDC is higher than the set value and needs to be lowered, the motor rotates in reverse to the rising time according to the control pulse.

The IVR 10 is controlled by the motor so that the _VDC approaches the set value based on the control pulse. When _VDC becomes lower than the reference voltage _{Vref_H1} , the control pulse generation circuit 34 stops the output.

The region of set value ± TS is a non-control region. Therefore, the control pulse generation circuit 34 does not output a control pulse in this region, and the IVR motor also stops moving, so that the value of _VDC is maintained in this region.

The applied voltage of the klystron is kept constant in the DeQ circuit 24. However, the influence of the input change causes an increase in suppression energy of the DeQ control, and the control state changes, so that a subtle change also occurs in the output state. This change has a major impact on the performance of the accelerator. In order to prevent this influence, high-precision control of _VDC is important.
Japanese Patent Laid-Open No. 11-194842 Japanese Patent Laid-Open No. 11-354038

  However, in the control circuit shown in FIG. 3, the IVR voltage setting of automatic control is generally controlled by a step waveform up to a set value. Therefore, the IVR causes a hunting operation unless the allowable range of setting is set wide due to the existence of a non-control period such as motor play and operation stop delay. That is, the motor cannot be stopped in the non-control region, and a phenomenon occurs in which the motor repeats rotation in the UP direction and the DOWN direction alternately.

  In addition, if this uncontrolled region is widened, it becomes difficult to control small fluctuations in the input signal, and this fluctuation in output gives a fatal impact particularly on the performance of the accelerator.

  The present invention solves the above-described problems of the prior art, and an object of the present invention is to provide a control circuit that stably controls the output voltage of an accelerator power source using an induction voltage regulator with high accuracy.

  In order to solve the above problems, a control circuit according to the present invention is characterized in that the invention according to claim 1 is a direct current obtained by rectifying and smoothing the output voltage of the power supply device for an accelerator using an induction voltage regulator that regulates the output voltage. A control circuit that detects a voltage and feeds back a control signal to the induction voltage regulator so that a difference between the detected value and a set value becomes small, and a first reference voltage having a predetermined difference with respect to the set value A first comparator for comparing the value with the voltage value of the DC voltage, and the voltage value of the DC voltage is closer to the set value than the first reference voltage value based on the output of the first comparator. A control pulse generating circuit that outputs an H level control pulse as the control signal to the induction voltage regulator, and the gate is controlled in accordance with the output of the first comparator, and the setting is higher than the first reference voltage value. Second reference voltage that is close to the value And a second comparator that compares the voltage value of the DC voltage, and when the voltage value of the DC voltage is closer to the set value than the first reference voltage value, based on the output of the second comparator The DC voltage has a constant ON width determined by the performance of the induction voltage regulator until the voltage value of the DC voltage becomes closer to the set value than the second reference voltage value, and further the operating time of the induction voltage regulator And a short pulse generation circuit that outputs a short pulse having an OFF time based on the induced voltage regulator as the control signal.

  According to a second aspect of the present invention, in the first aspect, the first comparator, the second comparator, the control pulse generation circuit, and the short pulse generation circuit are configured by an internal program and perform digital control. Features.

  According to the first aspect of the present invention, since the control is performed in two stages of the control pulse and the short pulse, the range of the non-control region can be narrowed. As a result, it is possible to control the voltage set value with higher accuracy. Further, since the non-control region is a narrow range, the control by the short pulse is performed only by slightly deviating from the region. Therefore, more stable control can be performed. Furthermore, even a small input fluctuation can be controlled more sensitively by short pulse control.

  According to the second aspect of the present invention, a complicated module configuration is not required in the control circuit, which can contribute to cost reduction. Furthermore, the performance can be easily improved by using a small amount of internal programs and hardware using the current equipment.

  Embodiments of a control circuit according to the present invention will be described below in detail with reference to the drawings.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an accelerator power supply device using the control circuit of Embodiment 1 of the present invention, and FIG. 2 is a diagram showing the operation of the control circuit of Embodiment 1 of the present invention. In FIG. 1, the same or equivalent components as those in FIG. 3 are denoted by the same reference numerals as those described above, and redundant description is omitted.

  First, the configuration of the present embodiment will be described. As shown in FIG. 1, the control circuit 30b according to the present embodiment includes a first comparator 32, a control pulse generation circuit 34, a second comparator 36, a short pulse, and the like. The generation circuit 38 is configured.

Each configuration of the power supply device for an accelerator using the induced voltage regulator 10 for adjusting the output voltage is the same as that shown in FIG. The control circuit 30b (analog control or digital control) detects the DC voltage _VDC obtained by rectifying and smoothing the output voltage output from the induction voltage regulator 10, and reduces the difference between the detected value and the set value. The control signal is returned to the IVR 10.

In the control circuit 30b, the first comparator 32 compares the first reference voltage value having a predetermined difference with respect to the set value with the voltage value of the DC voltage _VDC .

The control pulse generation circuit 34 generates an H level control pulse based on the output of the first comparator 32 until the voltage value of the DC voltage _VDC is closer to the set value than the first reference voltage value. Continuously output to the IVR 10.

The second comparator 36 has a gate controlled according to the output of the first comparator 32, and a second reference voltage value that is closer to the set value than the first reference voltage value and the voltage value of the DC voltage _VDC. Compare

When the voltage value of the DC voltage _VDC is closer to the set value than the first reference voltage value, the short pulse generation circuit 38 determines that the voltage value of the DC voltage _VDC is based on the output of the second comparator 36. As a control signal, a short pulse having a constant ON width determined by the performance of the induction voltage regulator until it becomes a value closer to the set value than the value and having an OFF time based on the operation time of the induction voltage regulator is generated. Continuously output to the IVR 10. The pulse width of this short pulse is set at the drive performance limit of the IVR motor.

Next, the operation of the control circuit according to the first embodiment will be described with reference to FIG. Here, a case where _VDC is lower than the set value will be described. At the time of t ₀ , which is the start time, when V _DC is lower than the set value by a predetermined difference (TS) (V _DC <V _ref — _{L 1} = set value−TS), the control pulse generation circuit 34 Based on the output of the first comparator 32, a control pulse CP is output to the IVR 10 and controlled. The IVR 10 is controlled by the motor so that the _VDC approaches the set value based on the control pulse. When V _DC exceeds V _{ref_L1} that is the first reference voltage value (t ₁ ), the control pulse generation circuit 34 stops the output.

Next, the short pulse generation circuit 38 outputs the short pulse SP to the IVR 10 based on the output of the second comparator 36 and controls it. The gate of the second comparator 36 is controlled according to the output of the first comparator 32. Therefore, until the value of the DC voltage V _DC exceeds the first reference voltage value, the second comparator 36 does not output and no short pulse is generated. The IVR 10 is controlled so that _VDC approaches a set value by the motor based on the short pulse. When V _DC exceeds V _{ref — L2} that is the second reference voltage value (t ₂ ), the short pulse generation circuit 38 stops the output.

Even when _VDC is higher than the set value, the same operation is performed although not shown. That is, at the time of t ₀ , which is the start time, when V _DC is higher than a set value by a predetermined difference (TS) (V _DC > V _ref — _H1 = set value + TS), the control pulse generation circuit 34 Controls the output of the control pulse CP to the IVR 10 based on the output of the first comparator 32. After that, when V _DC decreases from the first reference voltage value V _{ref_H1} (t ₁ ), switching to short pulse control is performed, and the short pulse generation circuit 38 generates the short pulse SP based on the output of the second comparator 36. Output to IVR10 and control. When _VDC falls _below V _{ref_H2} , which is the second reference voltage value (t ₂ ), a non-control region is entered and control stops.

As described in the prior art, the IVR 10 has terminals on the UP side and the DOWN side, and the rotation direction of the motor is reversed between the UP and the DOWN. Therefore, when _VDC needs to be lowered because it is higher than the set value, the motor rotates according to the control pulse as opposed to when it rises.

In the non-control region, neither the control pulse generation circuit 34 nor the short pulse generation circuit 38 outputs a control pulse or a short pulse as a control signal, and the IVR motor also stops moving, so the value of _VDC is Keep in this area.

For small changes such as input fluctuations, if the fluctuations exceed the range TC between V _{ref_L2} and V _{ref_H2} , which are non-control areas, the second comparator 36 detects this and detects a short pulse. The generation circuit 38 again generates and outputs a short pulse for control.

  The same control is possible when a stepping motor (a motor that rotates in step units determined by applying a pulse signal) is used for the IVR 10.

  Further, the control circuit 30b may be controlled by an analog circuit or may be digitally controlled. In the case of digital control, a programmable controller (PLC), FPGA, or the like can be used. In that case, the first comparator 32, the second comparator 36, the control pulse generation circuit 34, and the short pulse generation circuit 38, which are the configuration requirements of the control circuit 30b, are configured by an internal program and perform digital control.

  As described above, according to the control circuit according to the first embodiment of the present invention, control is performed in two stages, that is, a control pulse and a short pulse, so that the range of the non-control region can be narrowed. As a result, it is possible to control the voltage set value with higher accuracy. Further, since the non-control region is a narrow range, the control by the short pulse is performed only by slightly deviating from the region. Therefore, more stable control can be performed. Furthermore, even a small input fluctuation can be controlled more sensitively by short pulse control.

In the prior art, the region between V _{ref_L1} and V _{ref_H1} is a non-control region, and due to reasons such as IVR motor play and operation stop delay, a narrower range could not be controlled with a control pulse. By performing control with continuous short pulses, the non-control region can be narrowed down to a narrower range between V _{ref_L2} and V _{ref_H2} . The range of this non-control region is about 1/10 compared with the conventional case.

  When digital control is performed using a PLC, FPGA, or the like, a complicated module configuration is not required in the control circuit, which can contribute to cost reduction. Furthermore, it is possible to easily improve the performance of the control circuit by using a faint internal program and hardware change using the current equipment.

  The control circuit according to the present invention is applicable to a control circuit that stably controls the output voltage of the power supply device for an accelerator with high accuracy.

It is a block diagram which shows the structure of the control circuit in the power supply device for accelerators of the form of Example 1 of this invention. It is a figure explaining operation | movement of the control circuit of the form of Example 1 of this invention. It is a block diagram which shows the structure of the control circuit in the conventional accelerator power supply device. It is a figure explaining operation | movement of the conventional control circuit.

Explanation of symbols

10 Inductive voltage regulator (IVR)
12 Transformer 14 Rectifier circuit 16 Choke coil 18 Charging choke 20 Hold-off diode 22 Pulse shaping circuit (PFN)
24 DeQ circuits 30a and 30b Control circuit 32 First comparator 34 Control pulse generation circuit 36 Second comparator 38 Short pulse generation circuit

Claims (2)

A DC voltage obtained by rectifying and smoothing the output voltage of the accelerator power supply device using an induction voltage regulator for adjusting the output voltage is detected, and the control signal is set so that the difference between the detected value and the set value becomes small. A control circuit that feeds back to the regulator,
A first comparator for comparing a first reference voltage value having a predetermined difference with respect to the set value and a voltage value of the DC voltage;
Based on the output of the first comparator, an ON control pulse is output as the control signal to the induction voltage regulator until the voltage value of the DC voltage becomes closer to the set value than the first reference voltage value. A control pulse generation circuit;
A gate is controlled according to the output of the first comparator, and a second comparison for comparing a second reference voltage value, which is closer to the set value than the first reference voltage value, with a voltage value of the DC voltage And
When the voltage value of the DC voltage is closer to the set value than the first reference voltage value, the voltage value of the DC voltage is more than the set value than the second reference voltage value based on the output of the second comparator. The inductive voltage regulator uses as a control signal a short pulse having a constant ON width determined by the performance of the inductive voltage regulator until it becomes a value close to, and having an OFF time based on the operating time of the inductive voltage regulator. A short pulse generation circuit that outputs to
A control circuit comprising:   2. The control circuit according to claim 1, wherein the first comparator, the second comparator, the control pulse generation circuit, and the short pulse generation circuit are configured by an internal program and perform digital control.

Images