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3 Phase, Single Phase or DC Generation


hakonnissen
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Most of the cheap turbines I seem to find are either providing "wild" 3-phase AC (ie Voltage fluctuates along with RPM), or are rectifying the 3-phase to DC, which (judging by the heatsink sizes) must surely result in hefty losses.

 

I realise 3-phase is more efficient for generation and transmission, but when I only need single phase 220V, the equipment for 3-phase gets expensive and the load balancing gets rather complicated.

 

My one big advantage with rectifying to DC, is that as my hydro flow fluctuates I should be able to use everything generated (more water = more RPM = more Watts). If I understand correctly AC generation makes use of a dumpload to control surplus energy.

 

If I only want single phase 220V and don't want to waste energy on rectifying to DC and then inverting back to AC for loads, how do I clean the power to ensure constant voltage and frequency?

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  • 4 weeks later...

Most of the cheap turbines I seem to find are either providing "wild" 3-phase AC (ie Voltage fluctuates along with RPM), or are rectifying the 3-phase to DC, which (judging by the heatsink sizes) must surely result in hefty losses.

 

I realise 3-phase is more efficient for generation and transmission, but when I only need single phase 220V, the equipment for 3-phase gets expensive and the load balancing gets rather complicated.

 

My one big advantage with rectifying to DC, is that as my hydro flow fluctuates I should be able to use everything generated (more water = more RPM = more Watts). If I understand correctly AC generation makes use of a dumpload to control surplus energy.

 

If I only want single phase 220V and don't want to waste energy on rectifying to DC and then inverting back to AC for loads, how do I clean the power to ensure constant voltage and frequency?

 

You'll never be able to maintain a constant voltage and frequency WITHOUT electronics on something like a water or wind turbine.

 

How many watts is it? If it is more than a couple of hundred watts, I'll not complain about the little drop across the diodes of the rectifier, especially in a 3-phase system. You gain by getting a smoother DC out which is easier to smooth further if needed. From here, the inverter will provide you with a constant voltage and frequency at single phase 230 V provided the hydro keeps on turning of course.

 

Whether or not a dump load is used, is determined entirely by the type of alternator in use. Is it a PM type (permanent magnets), or does it have an excitation field? In the former case, a dump load is usually employed and in the latter case electromagnetic feedback or electronic control. Even with a dump load, electronic control is necessary. You will always have losses, more so when using a dump load.

What will be the AC loads you talk about?

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If diode losses bother you, look at Schottky diodes. They have a lower voltage drop, but they also have a lower reverse breakdown voltage and they have a tiny bit of reverse leakage. They also cost more. But of chosen correctly it will only drop 0.2V instead of the usual 0.6 to 0.7, so two thirds less heat/losses.

Sent from my GT-I9195 using Tapatalk

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