JPH0536523A - Pulse current supplying apparatus - Google Patents

Abstract

PURPOSE:To suppress leakage current of a transistor which may influence a residual magnetic field of an electromagnet in an OFF state below a prescribed value or lower by providing a reverse bias means for applying reverse bias voltage to a load electromagnet in order to reduce leakage current flowing in the load electromagnet when a switch is turned OFF to a predetermined value. CONSTITUTION:During a current rising period, current is supplied to a load electromagnet 14 via a series circuit of a first d.c. power source 2, a first switch 10, a second dc. power source 1 and a second switch 8, while during a flat top period, the second switch 8 is turned OFF so that current is supplied to the load electromagnet 14 via a series circuit of the first d.c. power source 2, the first switch 10 and a diode 12. In such a pulse current supplying apparatus, a reverse bias moans (a reverse power source 3, a switch 11, etc.) is provided for applying reverse bias voltage to the load electromagnet 14 in order to reduce leakage current flowing in the load electromagnet 14 via the first switch 10 when the first switch 8 is turned OFF.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse current supply device for supplying a pulse current having a predetermined rise time and a predetermined flat top (maximum current state) time to a load electromagnet in a predetermined cycle. The present invention relates to a pulse current supply device having a control function of suppressing a leak current of a power supply output (called a flat base) to a predetermined value or less.

[0002]

2. Description of the Related Art At present, a stable beam supply is required,
Various electromagnet power supply devices used for applications such as accelerators have been put into practical use. Among the various electromagnet power supply devices, compared with the conventional DC type electromagnet power supply, the pulse current energization method has a regenerative function, so that the conversion efficiency is high and the power consumption is low, so excellent characteristics can be expected.

FIG. 4 is a main circuit system diagram showing a configuration of a typical example of such a pulse current supply device. In the figure, 1 is an upper stage DC power supply (hereinafter, referred to as a second DC power supply), 2 is a lower stage DC power supply (hereinafter, referred to as a first DC power supply), 4 and 5 are DC filter reactors, and 6 and 7 are The direct current filter capacitor supplies direct current power to the load electromagnet 14 for raising a current and direct current power for maintaining a flat top current whose constant current is controlled with a constant accuracy. The direct current section has switches (transistors in this example) 8 and 10 for performing pulse energization, and controls the supply of pulse current, respectively. Dio
The switch 12 is a switch 8 (hereinafter,
Via the second switch), the second DC power supply voltage is applied in a positive polarity on the cathode side, so that the second DC power supply voltage becomes non-conductive, and the second DC power supply voltage and the first DC power supply voltage are superposed. Obtain a high output voltage. Further, the diode 12 is in a conducting state at the time of flat top current, and is used to form a current supply circuit in the flat top portion of the pulse current pattern. The diode 9 forms an electric circuit for regeneration. The diode 9 is in a non-conducting state when the current is raised and the flat-top current is supplied, but the second switch 8 and the first switch 10 are turned off and are in a conducting state when the current supplied to the load electromagnet 14 is regenerated. Becomes At the time of regeneration, a current regenerating electric path for the load electromagnet 14, the diode 9, the capacitor 6, the diode 12, the shunt 73, and the load electromagnet 14 is formed. The output current is detected by the shunt 73. 70 is a control block for controlling the second switch 8, 71 is a control block for creating an output current reference, 72
Shows an operational amplifier for constant current control of the output current.

FIG. 5 shows waveforms at various parts for explaining the operation of the conventional pulse current supply device shown in FIG.
5A shows the collector-emitter voltage VCE of the second switch 8, FIG. 5B shows the collector-emitter voltage VCE of the first switch 10, and FIG. 5C shows the output current waveform. There is. In the current rising mode period from time t0 to time t1, the ON signal is given from the control block 70 to turn on the second switch 8, so that the second DC power supply 1 and the second DC power supply 2 are set to the first DC power is supplied through the switch 10 and the second switch 8. In this mode, the first switch 10 controls the constant current by the operational amplifier 72. That is, the current reference IRE output from the control block 71
F is differentially amplified by the feedback current signal IFBK detected by the shunt 73 and the operational amplifier 72, and the first switch 10 is subjected to constant current control so that the output current matches the current reference, and at a predetermined ratio within a predetermined time. Turn on the current.

Next, in the flat top period from time t1 to time t2, the ON signal of the control block 70 is turned off,
The second switch 8 is turned off. For this reason, the flat top current constant control mode is used only for the first DC power source 2 and the first DC power source 2.
It is supplied as a direct current whose constant current is controlled by the switch 10 through a diode 12 which becomes conductive. Next, during the current regeneration mode period from time t2 to t3, the second switch 8 and the first switch 10 are turned off, and the energy stored in the load electromagnet 14 is stored in the lower end of the load electromagnet 14, the diode. Anode of 9th and a 9th
The cathode of the capacitor 6, the positive side of the capacitor 6, the negative side of the capacitor 6, the anode of the diode 12, the cathode of the diode 12, the shunt 73, the electric circuit at the upper end of the load electromagnetic magnet 14, It is regenerated to the capacitor 6 of the DC power supply.

At times t3 to t4, the second switch 8 and the first switch
The switch 10 is also turned off and the current of the load electromagnet is zero, which is a current zero period, and after time t4, the above mode is repeated again to perform the operation of supplying the periodic pulse current.

[0007]

The conventional pulse current supply device described above still has the following problems. That is, when the device rated output current value becomes large, a large number of transistors forming the first switch 10 have a parallel configuration, and the leakage current tends to increase even in the switching-off state. There is a problem that the residual magnetic field of the electromagnet is affected and the offset fluctuates with respect to zero adjustment of the acceleration beam and the like, which is not desirable.

The present invention suppresses the leakage current of the transistor which affects the residual magnetic field of the electromagnet in the off state to a fixed value or less, and controls the fluctuation of the offset with respect to the zero adjustment of the acceleration beam and the like. It is intended to provide.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a first DC power supply during a current rising period,
A current is supplied to the load electromagnet through a series circuit of a first switch, a second DC power supply, and a second switch, and the second switch is turned off in a flat top period, and the first DC power supply, the In a pulse current supply device for supplying a current to the load electromagnet through a series circuit of a first switch and a diode, the load electromagnet is passed through the first switch when the first and second switches are off. Reverse bias means for applying a reverse bias voltage to the load electromagnet is provided in order to reduce the leakage current flowing through the load electromagnet to a predetermined value.

[0010]

According to the present invention, in order to reduce the leakage current of the pulse current supply device to a predetermined value, the direction of the current supplied to the load electromagnet by the reverse bias power source is set to be the opposite direction of the leakage current, The leakage current can be reduced to a predetermined value by appropriately controlling the value of the current supplied to the load electromagnet by the reverse bias power source.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a main circuit system diagram showing a configuration of a pulse current supply device showing an embodiment of the present invention. The same parts as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

The reverse bias power source 3, the switch 11, the control block 74 therefor and the resistor 13 constitute a reverse bias means. A reverse bias power source 3 applies a reverse bias voltage to the load electromagnet 14 via the resistor 13 according to the control of the switch 11 (transistor). 74 is a switch 11
In the block diagram of the control section, the residual magnetic field of the load electromagnet due to the leakage current when the first switch 10 is off is suppressed to a predetermined value or less by applying a predetermined reverse bias voltage. FIG. 2 is a time chart for explaining the embodiment of the present invention shown in FIG. FIG. 2A is a collector-emitter voltage VCE of the second switch 8, and FIG.
Is the collector-emitter voltage VC of the first switch 10.
E, FIG. 2C shows the collector-emitter voltage VCE of the switch 11, and FIG. 2D shows the output current waveform.

During the period from time t0 to t1, the current rising mode is set.
Mode, time t1 to t2 indicates a constant flat top current control mode period, time t2 to t3 indicates a current regeneration mode period, and time t3 to t4 indicates a reverse bias period. In this time t
From 0 to t3, the control operation is the same as that of the conventional example shown in FIG.
The description of the operation is omitted.

FIG. 3 shows a detailed structure of the control block 74 and an equivalent circuit of a main circuit through which a leakage current flows. Details of the leakage current suppression control during the reverse bias period from time t3 to t4 will be described with reference to FIG. In FIG. 3, reference numeral 10a indicates the equivalent resistance when the first switch 10 is turned off, which is reduced due to the large number of parallel connections.

The leakage current I0 flows through the equivalent resistance 10a from the DC filter capacitor 7 to the diode 12, the load electromagnet 14, the shunt 73 and the DC filter capacitor 7 as shown by the dotted line. Other circuits such as the DC filter capacitor 6 and diode 9 are separated because the switch 8 is off. The control block 74 of the switch 11 is a control block 17, which creates a current reference,
It is composed of an operational amplifier 16. The leakage current I0 to the output is detected by the shunt 73, differentially amplified by the current reference IREF2 and the operational amplifier 16, and a reverse bias voltage is applied to the switch 11 so that the output leakage current I0 matches the current reference IREF2. Constant current control is performed, and the leakage current I0 is suppressed below a predetermined value.

[0016]

As described above, according to the present invention, the reverse bias means is provided and the output leakage current is set to a predetermined value or less. Therefore, the acceleration beam is used for an application such as an accelerator.
It is possible to control the fluctuation of the offset with respect to the zero adjustment of the beam, and to achieve a reliable and stable beam supply. Further, since zero adjustment is automatically compensated, it is possible to save the trouble of regular inspection and daily adjustment.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a time chart of the waveform of each part in FIG. 1 for explaining the operation of the present invention.

FIG. 3 is an equivalent circuit diagram for explaining the operation of the present invention.

FIG. 4 is a block diagram of a conventional device.

FIG. 5 is a time chart of waveforms of each part for explaining the operation of the conventional device.

[Explanation of symbols]

1 ... Upper DC power supply 14
… Load electromagnet 2… Lower DC power supply 70…
Control block 3 ... Reverse bias power supply 71
… Making current reference 4,5… Reactor for DC filter
Control block 6, 7 ... Capacitor for DC filter 72
... Operational amplifier 8, 10 ... Switch 73 ... Shunt 9, 12 ... Diode 74 ...
Control block 13 ... Resistance

Claims (1)

Claims: 1. A current is supplied to a load electromagnet through a series circuit of a first DC power supply, a first switch, a second DC power supply, and a second switch during a current rising period. In the flat top period, the second switch is turned off, and the pulse current supply device supplies current to the load electromagnet through the series circuit of the first DC power source, the first switch, and the diode. Reverse bias means for applying a reverse bias voltage to the load electromagnet to reduce a leakage current flowing through the load electromagnet through the first switch to a predetermined value when the first and second switches are off. A pulse current supply device characterized in that