Paralleling Power Supply Units Made Easy ???
I am considering paralleling a couple of 20a variable adjustable psu's for 40a charging. According to what I have read on the world wide inter-web, it can be done quite easily, provided the following ...
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The ac has no influence. I'm talking about the cable between the PS and the load. Each PS needs its own cable to the load.
Let's say both cables have exactly 10 mohm resistance. That means:
V1 - V2 = (I1 - I2) * R_line
If the difference in currents is 5A, then the difference in voltage between the two supplies is:
V1 - V2 = 5A * 10 mohm = 50 mV.
The two supplies must be within 50 mV of each other for them to "share". The supply with the higher voltage will output 5 more amps.
If you increase R_line you can get more current sharing. To get the same output current you have to increase the voltage of V1 & V2 though.
Let's say both cables have exactly 10 mohm resistance. That means:
V1 - V2 = (I1 - I2) * R_line
If the difference in currents is 5A, then the difference in voltage between the two supplies is:
V1 - V2 = 5A * 10 mohm = 50 mV.
The two supplies must be within 50 mV of each other for them to "share". The supply with the higher voltage will output 5 more amps.
If you increase R_line you can get more current sharing. To get the same output current you have to increase the voltage of V1 & V2 though.
jrnymn7 wrote:Salvo wrote:
Some folks have problems reading the fine print. You can parallel power supplies in voltage mode as long as the supplies regulated voltage difference is less than the power cable line drop. They will however not share equally.
Salvo, are you referring to the ac line input to the psu? If so, how does one go about equalizing ac line voltage?
