Permanent Magnet Generator / Alternator
Post date: Nov 25, 2017 8:22:11 AM
Abbreviated PMG or PMA
These are available on Ebay, e.g. 4kW for approx. 200 USD
These are NOT standard generators. They are actually intended for wind turbines, and run at variable speed.
In order to use them, you need to rectifiy the "wild" AC to DC, and then invert it to standard AC again.
Typical data:12 Poles, 3phase, 4kW at 240V AC and 2800 RPM / 280Hz, 10 A per phase, or 16 A rectified
The voltage rises linearly with the RPM.
i.e.
28 Hz, 24 V AC, 400W
56 HZ, 48V AC, 800W
140 Hz, 120 V AC, 2kW
280 Hz, 240 VAC, 4kW
The rectified 240V AC will become 240V * root(3) = 415V DC. So your inverter needs to handle that kind of high DC.
Standard photovoltaic inverters normally accept only max. 145V DC.
http://www.midnitesolar.com makes suitable controllers.
Advantages: - cheap generator
- good, if you have very variable water availability
Disadvantages: - Expensive inverter needed (if you know a good source, let me know!)
- full power is only available at full RPM