Electronic – Using a transformer with 400 volt rated primary side with a 120 volt line


Is it possible to use a transformer rated for 360 to 400 volts on its primary side on a 120 volt line? Will it still perform adequately? And I would assume the turns ratios still apply?

This is the transformer in question: WE-LLCR Resonant Converter.

Also, I understand that the saturation current is that which the inductance drops off; however, this datasheet says the I-sat is 4 amperes, but it's rated for 8 amperes output current. Why is this so?

I will be using this in an SMPS at 100 kHz.

Best Answer

If you look at the datasheet, it says Resonant Converter. The only resonant converters that I have worked on were to get high voltage outputs without feedback. I think there may not be any difference in the transformer construction and you can use it for the much more common PWM scheme SMPS.

The 4A saturation current spec is for the primary.

The transformer can function for 400V or below. One of the key spec here is the primary inductance -- 400uH, it determines the current rise for a given on time. Back of the envelope calculations: at 120VDC input, 0.5us on time (50% of the period of 100KHz), discontinuous current mode (flyback topology), the transformer can transfer no more than 45W. At 320VDC input, 320W. And these are assuming 100% efficiency.

SMPS can be fun, but be careful when dealing with 120V or greater. In the common flyback topology, the flyback voltage would add on top of that.