High Voltage DC to Low Voltage DC Converter Help

[DevLocus]

I am designing a HV (450 to 950 VDC) to LV (24 VDC) converter. I am having problems creating the controls for the switching transistor and choosing the transistor. The schematic is a standard buck converter with S being the transistor and sensing from just before the inductor. I would also like to try and squeeze a transformer in there to isolate the 24 volt line from the HV line. Any help would be appreciated.

 

[ScottyUK]

For the transistor you are probably looking at an IGBT. This will limit your switching frequency to a few tens of kHz, which means the magnetics will be relatively large and heavy and expensive compared to a design able to run at high frequency. There are any number of IGBT gate drive ICs and hybrid modules available from the likes of IR, Fuji, Toshiba, etc. If you're making high volumes it will pay you to develop your own circuit but for small quantities the packaged parts just make life so much easier.

The control circuit should be pretty standard.


----------------------------------

Sometimes I only open my mouth to swap feet...

 

[DevLocus]

Unfortunately I already looked at that option and ruled it out because I would need to draw power from this power supply in order to power the drive IC. I only have the HV line to work with. I am sorry for forgetting to mention that in the description of my problem.

 

[CJCPE]

Since you want a transformer for isolation, design a simple inverter to change the HV DC to AC for the primary and drop the voltage with the transformer. Put a simple rectifer circuit on the secondary and a voltage regulator if necessary.

 

[DevLocus]

I have never designed an inverter and all the ones I find online do not simulate so I can't check my results and test the circuit for outputting a clean enough signal.