hakonnissen Posted January 12, 2016 Share Posted January 12, 2016 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? Quote Link to comment Share on other sites More sharing options...
SOLARWIND Posted February 4, 2016 Share Posted February 4, 2016 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? Quote Link to comment Share on other sites More sharing options...
___ Posted February 5, 2016 Share Posted February 5, 2016 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 SOLARWIND 1 Quote Link to comment Share on other sites More sharing options...
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