800V switch on/off by using Micrcontroller

[Naveed_16]

hiz to all
i am stuck in a problem. i need help for that

Problem:

i have a capacitor bank of 40J and 800V. i have to explode resistor on some energy. as the figure describe there will be some high energy surge and discharge on the resistor.

i need a switch which can hold this no-repetitive current pulse. this trigger will be be on the bases of Micrcontroller.

 

[FvM]

I would primarly think about a thyristor with trigger transformer.

 

[Naveed_16]

any circuit diagram? so that i would have a starting point

 

[juicedry]

Do you need to do this in a very short period of time? Say nanosecond time period and delivery a very high peak current. If so, look at avalanche transistors and string them together in series.

 

[Naveed_16]

no..... its jst a switch. you can say mechanical button can fulfil my need but the problem is Microcontroller. i want to turn on this capacitor bank base on some if-else condition. for that purpose i need some circuit which can trigger on the bases of micrcontroller control pin high or low.

 

[juicedry]

Don't you need to discharge the capacitor bank with the maximum amount of energy into the resistor? To maximise your energy transfer from the capacitor you need your switch to turn-on quickly.

See this **broken link removed**.

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Otherwise use a 1200V IGBT such as here

 

[mtwieg]

FvM's suggestion of a thyristor/SCR would probably be best. Look up control circuits for simple spot welders. To be safe you want the MCU isolated from the thyristor, via either an optocoupler or pulse transformer.

 

[juicedry]

Ignore my suggestions, as I mis-read your need for 40Joules. I back the SCR option.

 

[schmitt trigger]

Agree with the thyristor option. There are devices which can switch a kiloamp in microseconds. They have to be driven hard, so a transformer based trigger would be better.

 

[Naveed_16]

Thx for replying

my problem is not KAmp..... my prob is 800V with not repetitive surge as well as size. the size should be like a transistor

can you suggest any thyristor? i am new in thyristor field. have tried to find suitable but i got only tension

 

[FvM]

Any thyristor with 6 or 10A current rating and 800 V blocking should be able to switch the 100 A/1 ms pulse.

 

[Naveed_16]

how to switch surge, Current Spike?

hi to all

i have a capacitor bank of 40 joules of energy on 800VDC. i want to discharge it across a resistor so that it burn.

ofcourse its a nin-repetitive current across a resistor.

the switching of this non-repetitive current is from Microcontroller

can anyone recommand me any component

 

[jiripolivka]

Re: how to switch surge, Current Spike?

hi to all

i have a capacitor bank of 40 joules of energy on 800VDC. i want to discharge it across a resistor so that it burn.

ofcourse its a nin-repetitive current across a resistor.

the switching of this non-repetitive current is from Microcontroller

can anyone recommand me any component

For such switching I used a controlled spark gap. The third electrode in the spark gap was the trigger, and I used a high voltage (10-30 kV) pulse from a circuit like that used in a photo-flash with a Xenon tube.
There are also triggerable gas-discharge tubes but my solution worked well and is low-cost.
Use screw-adjustable electrodes in the spark gap, and use tungsten (Wolfram) ends to carry spark current if you can.

 

[kam1787]

Re: how to switch surge, Current Spike?

you might look into using a high-voltage hi-current SCR

 

[Naveed_16]

all thyristor and SCR are n-type. i have to connect them after the load (reference to ground). my prob is my circuit requirement is that i have to connect the switch before the load

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For such switching I used a controlled spark gap. The third electrode in the spark gap was the trigger, and I used a high voltage (10-30 kV) pulse from a circuit like that used in a photo-flash with a Xenon tube.
There are also triggerable gas-discharge tubes but my solution worked well and is low-cost.
Use screw-adjustable electrodes in the spark gap, and use tungsten (Wolfram) ends to carry spark current if you can.

can you tell me any component number and circuit which can do what you said

 

[FvM]

all thyristor and SCR are n-type. i have to connect them after the load (reference to ground). my prob is my circuit requirement is that i have to connect the switch before the load

No, you don't. You'll consider a trigger transformer as suggested in post #2. It's a really simple and straightforward solution.