Adriaan Kragten writes:
Report KD 730 can be copied for free from my website: www.kdwindturbines.nl
at the menu KD reports. The title of this report is: “Ideas about a 28-pole, 3-phase permanent magnet generator using the housing and winding of a 4-pole asynchronous motor frame size 80”. This generator is using 28 neodymium magnets size 40 * 7 * 3 mm and the magnet costs only about € 25. It is expected that this generator can be used with the original 230/400 V winding for 24 V battery charging if the winding is rectified in delta.
I have added figure 1 out of this report as an attachment and you can use this figure in a blog about this message.
ADDED 16th January:
Hereby I want to draw your attention to two KD-reports about rectification of an AC current.
Report KD 340 describes 1-phase, 3-phase and 2-phase rectification. Originally only star en delta rectification of a 3-phase current were described but recently I have added chapter 3.2.3 about rectification with three separate 1-phase bridge rectifiers. This way of rectification results in a somewhat higher voltage and power than star rectification but the rectifier losses are higher as the current always flows through six diodes.
Report KD 712 describes 5-phase and 9-phase rectification. Originally only 5-phase rectification was described but recently I have added chapter 6 in which rectification of a 9-phase winding is described. It appears that there are two ways to rectify a 9-phase winding and the way which is described in chapter 6.2 is favorable because this results in the highest power. The winding is split into three, 3-phase windings which are rectified separately. The three, 3-phase rectifiers are connected in series. The advantage of 9-phase rectification is that there is almost no fluctuation on the DC voltage and the DC current. This is of interest if the wind turbine is grid connected by a 3-phase inverter because it eliminates the need of using capacitors to flatten the fluctuations.