Difference between HV and LV output LLC converter?

[waveboy]

From what i see, there is essentially no difference in an LLC for 15kv, 2kw output, and an LLC for 2kw, 200V output.

...other than the obvious different turns ratio....and the need for special HV isolation material and clearance.
Also the fact that you are forced to do an "Integrated transformer" at high voltage, because you simply cant get tight coupling.
...This in turn means, that you cant do a tight coupled LLC transformer with a pllel LMag.....(to reduce RMS current in the primary coil).
..Also, there could be noise issues if you are dividing down a high voltage output down to a 2.5V reference, say.
Also, i reckon it might be good to have it on light load at startup, and just have a pre-charge SMPS to take it up to 15kv.....then again, a long soft start at high frequency might do the trick.
Also, high Z nodes can get induced up to high voltage by the high E field.....so "quenching" resistors may be needed at certain points, to prevent nodes getting induced up in voltage.
Also, sharp pointed metal bits shoudl be kept away from circuitry, as they will attract a high E field to them...eg , the corner of a metal tab TO220.
Also, theres the obvious spacing and clearancing, creepaging.

Other than that, i'd say a high voltage LLC (15kv say) has little essential differences from a 200v output one.
Would you agree? (obvious differences accepted, eg, the output didoes and caps will be much higher voltage rated etc etc).

 

[sunnysky]

There is an obvious difference in the rated load impedance, which determines the ZL(f) and Zc)f) impedances which may affect cost, Q and type of components, effects of parasitics and creepage on the layout to maintain the same thermal and dielectric breakdown margins.

Rated Load
===========
15kV²/2kW = 112 kΩ @ 133 mA
200V²/2kW = 20 kΩ @ 10A

Impedance ratio affects frequency ratio = 5.6 of critically damped RLC at rated load.

Sharp points reduce the air dielectric breakdown voltage by about a factor of 4 compared to a smooth curve as I recall. Creepage may have a different ratio.

 

[Amit Bajpayee]

There are a few critical differences between HV and LV output LLC converters. For example, an HV output converter is designed to produce higher voltage levels than an LV output converter. It can handle more power loads with less risk of overload or damage. An HV Output Converter typically has features such as automatic level control and surge protection.
An LV Output Converter, on the other hand, is usually less expensive and is suited for applications where lower voltages are necessary, such as in small appliances or medical equipment.

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