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Maximum operating frequency

Thread starter #1
Hello people.
I want to use an IGBT for SMPS. Datsasheet link is given below. Can anyone tell what will be the maximum operating frequency? ALso what does the line " Ultra-Low Vsat PT IGBTs for
up to 10kHz Switching" in the top left corner of the first page means??
Does it mean that maximum operating frequency can not be more than 10khz??? Please explain the meaning of the line. Thanks in advance.

DATASHEET>>>> https://www.mouser.in/datasheet/2/205/DS99584B(IXGK-X400N30A3)-479723.pdf
 

unclejed613

Well-Known Member
#2
adding the rise time and fall time, and inverting gives 10khz.
 

rjenkinsgb

Active Member
#3
For a switching device, the rise and fall times are when a device is between it's "on" and "off" states - it's resistance is changing rapidly & that's when most power loss (and dissipation) occurs.

For efficient switching operation, the total on and off times should be no more than a small fraction of the total cycle time., so the device is in a stable fully-on or fully-off state (= minimal power dissipation and losses) for as long as possible.

For the device you mention, the sum of the on and off times is less than one microsecond, which is quite good for such a high-rated component.
The advised 10KHz maximum switching frequency means the transitions times are under 1% of the cycle time, giving good overall switching efficiency.

Remember that you do not need to use a single large device for a high-power switch - several smaller (and possibly faster) devices operating in tandem can give better switching characteristics plus circuit layout and heatsinking can be easier as power and currents in any one place are lower.

You could also consider devices in more suitable packages - eg. with screw terminals and isolated heat sink attachment faces such as these:
https://docs-emea.rs-online.com/webdocs/15e9/0900766b815e9d3f.pdf
https://docs-emea.rs-online.com/webdocs/1267/0900766b812671f6.pdf

Or for PCB mounting, each of these has three pairs of transistors you can use together; two modules would give you your 200A rating, at around £20 / $25 per module.
https://docs-emea.rs-online.com/webdocs/135d/0900766b8135d98f.pdf


Note that if you are trying to achieve 200A output at low voltage, the switching devices (on the high voltage side) do not need the same current rating; eg. if you were working with an input of 120V and an output of 12V, the input side current would not be a lot over 20A RMS.
 
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