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V/H power supply


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I'm busy building a 1.1Kw variable frequency/volt drive. I'm at a stage of building the power supply. I can see two basic routes forward

1. Isolated power supply

Isolate is basically keeping the high and low voltages separate.


2 None isolated -- use of transformers and opt-isolators


My main power supply contender, is a buck converter drawing power of the mian dc bus.


My main concerns are: noise, floating voltages and safety.

My main reason for using this type of power supply is cost.


The question is have I missed out any other points that I should be concerned with.





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Hello Carl


I assume that you are working with a three phase inverter, in which case you have six switches (IGBTs) to control. The three bottom switches have a common emitter connection on the negative rail so they can have a common power supply. The other three switches have their emmiters connected to the three outputs so each of the upper switches needs to have an isolated supply. That gives four isolated supplies plus the supply to run the electronics. I is possible to tie the electronics to the negative rail, but this is not advisable.


You will need to provide the isolated supplies plus the isolated driving circuits.


Best regards,

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