Report KD 668 is reviewed. This report describes a 24-pole radial flux PM-generator for the VIRYA-4.2 with no iron in the coils. Figure 1 and 2 have been changed such that the two disks are now lying within the sides of the armature. A new chapter 8 has been added in which an alternative stator is described which has 18 separate coils.

My website has been made safer by changing to https://www.kdwindturbines.nl. This has been done by the plugin Really Simple SSL.

A folder about the recently designed VIRYA-1.75W and the VIRYA-1.8W windmills is added at the menu VIRYA-folders.

Report KD 669 has been added to the menu KD-reports. The tittle of this report is: “Calculations executed for the 2-bladed rotor of the VIRYA-1.75W windmill (lambda design = 7, wooden blades) with a Chinese axial flux generator of Hefei Top Grand model TGET165-0.15KW-500R used for 12 V battery charging”. This generator has been tested for some years in combination with the VIRYA-1.65 rotor with cambered stainless steel blades but this rotor appeared to be too noisy. It is expected that the VIRYA-1.75 rotor with wooden blades will be more silent and that the maximum power is higher because of the larger rotor diameter.

KD 669 contains detailed drawings of the rotor and the generator bracket. The head and the tower of the VIRYA-1.81 can be used. Photos of the drawings of head and tower are given in the manual part 2 of the VIRYA-1.81 which can be copied from my website. The big advantage of the VIRYA-1.75 is that no generator has to be built. The used generator has been measured (see KD 595) and can be ordered directly in China. The generator is of type axial flux but the housing is completely closed.

Report KD 668 has been added to the menu KD-reports. The tittle of this report is: “Ideas about a 24-pole permanent magnet generator with a stator with no iron in the coils for the alternative VIRYA-4.2 rotor for battery charging or for combination to the 1.1 kW, 3-phase asynchronous motor of a centrifugal pump”. So the VIRYA-4.2 with this generator can be used in two different ways depending on the winding which is chosen. This 24-pole PM-generator is rather light for its armature volume as it has a hollow armature and aluminium bearing covers. It might be possible to use this generator as synchronous motor to drive an electric car or boat. This use is explained in chapter 7 of KD 668.

Report KD 667 has been added at the menu KD-reports. The title of this report is: “Ideas about a 12-pole permanent magnet generator using a motor housing frame size 100 and a stator with no iron in the coils for use in combination with the VIRYA-3B3 rotor”. This report describes a bigger generator using the same magnets and the same principles as used for the 8-pole generator as described in report KD 644. The main advantages of a PM-generator with no iron in the coils are that it has a high peak efficiency as there are no iron losses and that it has no clogging torque. This results in a low starting wind speed and the VIRYA-3B3 with this 12-pole generator can therefore be used in regions with low wind speeds.

Report KD 644 in which the 8-pole PM-generator is described, has been reviewed. To find a heat resistant glue with which the Delrin armature bush can be glued in the aluminium housing, can be difficult. Therefore an alternative has been described in chapter 4 for which the Delrin bush is connected to the housing by six M8 bolts.

Report KD 484 in which the VIRYA-3B3 rotor is described, is reviewed. A photo of the generator drawing with drawing number 1201-01 has been added in appendix 2. As the drawing is originally made on A1 format, a print of the photo on A4 format will be too small to read the measures but the measures can be read on the computer screen if the scale is enlarged. Manufacture of the wooden rotor blades of the VIRYA-3B3 is rather easy as the blades have a constant chord and no twist.

Report KD 664 has been added to the list of public KD-reports. The title of this report is: “Calculations executed for the 2-bladed rotor of the VIRYA-1.8W windmill (lambda design = 6.25, wooden blades) used in combination with an 8-pole permanent magnet generator frame size 71 with a stator with no iron in the coils”. Report KD 664 contains detailed drawings of the rotor and the hub. This rotor is meant for the generator as described in report KD 644.

Report KD 465 which was already written in 2011 has been reviewed and added at the menu KD-reports. The title of this report is: “Calculations executed for the 2-bladed rotor of the VIRYA-1.5 windmill (lambda design = 4.5, steel blades) with generator frame size 71 and original motor shaft”. This report has been made public because it might be possible to use the given rotor in combination with the 34-pole PM-generator which is described in public report KD 580 or with the 8-pole PM-generator which is described in report KD 644.