RU209507U1 - Rotary magnet fast current source - Google Patents

Abstract

The utility model relates to accelerator technology and is used in the U-1.5 charged particle accelerator, aimed at reducing losses during the transfer of a proton beam from LU-30 to the U-1.5 orbit or to the measuring branch. The specified technical result is achieved by powering the rotary magnet from a pulsed current source with a PWM frequency of 40 kHz, which increases the stability of the current on the "plateau" and the forced output of energy from the magnet to the resistors using a switch with a quasi-constant output voltage in a time less than the time between the end of one and the beginning of another cycle U-1.5.

Description

This utility model relates to accelerator technology, namely to power supplies for magnets, and can be used in accelerator complexes of charged particles.

Rotary magnet - an electromagnet that serves to redirect the proton beam into one or another channel.

The device for current stabilization belongs to the field of industrial electronics.

The set of features closest to the set of essential features of the claimed utility model is inherent in the well-known device IST-500/230, which is a stable current source for powering the rotary magnet of the proton beam input channel from the LU-30 linear accelerator to the U-1.5 ring accelerator.

A well-known stable current source is a DC power supply Iout=500A, Uout=100 V, containing:

- thyristor rectifier with asynchronous control circuit,

- current adjuster,

- output current sensor,

a comparison circuit; and an error amplifier driving the rectifier control circuit. [Cm. Patent: SU 1455987 A1]

The disadvantage of the known device, taken as a prototype, is the low speed.

This drawback is due to the low conversion frequency - 300 Hz.

The known device does not allow to achieve the output of energy from the magnet in less than 60 milliseconds. This is due to the low inverting voltage - 100 V.

The task to be solved by the claimed utility model is the development and replacement of an obsolete magnet power source, made according to the scheme of a 3-phase bridge rectifier with an asynchronous pulse-phase control system.

The object of development is a controlled current source with a maximum current of 250A, a voltage of 50V with a fast energy output from the load. the current of the rotary magnet in 60 milliseconds should decrease from the nominal - 220A to 0A. Magnet inductance - 36.5 mH.

The technical result (effect) of the present utility model is the rapid removal of energy from the bending magnet: part of the series of LU-30 cycles is directed to one channel, part - to another without beam loss.

The task is most simply solved by executing the source according to a key circuit with pulse-width modulation with a conversion frequency of 40 kHz. The problem of fast energy output is solved with the help of an additional device - a switch.

The power sources of the correction magnets, rotary magnets are controlled by pulses generated by the timer system of the U-1.5 "Booster" control panel. This source uses the following control pulses:

- reference, with pulse-width modulation (PWM), the signal sets the source current value.

- impulse In (start of work) allows the source to work.

- Ti impulse - injection (injection of a proton beam) into U-1.5 at this moment, we measure the source current and record it on the display. The magnitude of the current directly affects the correct injection.

- impulse "end of work" disables the work of the source.

The key switch consists of 6 controlled switches made on insulated gate bipolar transistors (IGBTs) that support the output of energy from the magnet at a quasi-constant voltage; the main key that disconnects the load from the source and the bypass key, made on IGBT modules. Overvoltage protection in case of improper operation of the switch is carried out by 2 thyristor arresters for 100 and 450 volts.

The utility model is illustrated by block diagrams (Fig. 1, 2) In Fig. 1 shows a block diagram of a current source made according to a standard key circuit with pulse-width control. The constant component extracted from the reference PWM signal is compared with the output voltage of the current sensor, which is proportional to the load current, and the difference signal is fed through the error amplifier to the PWM controller, which generates a signal for the PWM inverter that generates the load current. The circuit is covered by 100% negative feedback, i.e. the load current with an accuracy of 0.5% corresponds to the PWM signal of the support. The accuracy is determined by the LEM current sensor - LT 200s.

In FIG. 2 shows the block diagram of the switch. The commutator is designed to extract energy from the magnet in less than 60 ms.

The control device, upon receiving the “end of work” pulse, stops the operation of the current source, then opens the shunt switch to discharge the filter inductances, then opens 6 control switches, then closes the main switch switch, disconnecting the load from the source. The energy from the magnet begins to be output to 7 11 Ohm resistors connected in parallel. The voltage at the magnet terminals becomes equal to 400 V. Um=Im*Rн The control device, by closing the control switches one by one, maintains a quasi-constant energy output voltage of approximately 400 Volts. The 100 V arrester protects the output of the source from overvoltage in case of incorrect operation of the shunt switch. The 450 V arrester protects the magnet from overvoltage in the event of incorrect operation of the control keys.

In FIG. 3 shows oscillograms of the source operation.

The left oscillogram shows the increase in load current

The time scale is 250 milliseconds per division.

Load current - 50 amperes per division.

Load voltage - 10 volts per division.

The right waveform shows the load current decay

The time scale is 5 milliseconds per division.

Load current - 50 amperes per division.

Load voltage - 100 volts per division.

Claims (1)

A high-speed current source for powering a rotary magnet, containing a current generator, an output current sensor, a comparison circuit, an error amplifier that controls the power module, characterized in that it consists of a source made according to a key circuit with pulse-width modulation with a conversion frequency of 40 kHz; a switch that provides fast, forced output of energy from the magnet, consisting of 6 controlled switches made on IGBT transistors that support the output of energy from the magnet at a quasi-constant voltage; the main key, which disconnects the load from the source, and the bypass key, made on BTI3 modules; two thyristor arresters for 100 and 450 volts, which protect against overvoltages in case of incorrect operation of the switch.

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