Some recent new reports about small PM-generators have been added to chapter 6 of KD 341. A new chapter 7 has been added to KD 341. In this chapter, the magnet costs of the 26-pole radial flux generator as described in report KD 632 are compared to the magnet costs of the 8-pole axial flux generator as described in report KD 631. In chapter 7 also a simple methode is given to compare the maximum torque levels of both generators.
Reports KD 631 and KD 632 have been added to the list of free public KD-reports. KD 631 describes the 8-pole axial flux generator of the VIRYA-1.81. This generator has eight round neodymium magnets with a diameter of 45 mm and a thickness of 15 mm. It has a synthetic stator sheet which prevents the generation of eddy currents. KD 632 describes a 26-pole PM-generator using the housing of a 4-pole, 3-phase, 0.75 kW asynchronous motor frame size 80 and 26 neodymium magnets size 40 * 7 * 3 mm.
A new chapter 9 has been added to report KD 626 about the axial flux generator of the VIRYA-1.25AF. In this chapter the following measurements and conclusions are given for a steel stator sheet with a thickness of 3 mm. The sticking torque isn’t fluctuating for low rotational speeds. The pulling force in between the armature sheet and the stator sheet is 70 N. The rise of the stator temperature is 6 degrees C after running for 10 minutes at a rotational speed of 735 rpm. The power loss due to eddy currents in the stator sheet is only 8 W at the maximum loaded rotational speed of 650 rpm. The unloaded AC voltage for one coil with a test winding of 110 turns is 1.32 V for a rotational speed of 250 rpm, so the coils of the VIRYA-1 can also be used for the VIRYA-1.25AF.
Report KD 340: Rectification of 3-phase VIRYA windmill generators is reviewed. The curves which give the current I as a fuction of the phase angel have been modified such that the DC current for delta rectification is now lying a factor square root of 3 higher than the curve for star rectification. It was just the opposite and although the curves are relative, this might be confusing.
Reports KD 608 and KD 571 have been reviewed. Report KD 626 has been made public. Report KD 626 describes the VIRYA-1.25AF windmill. This windmill has an axial flux generator which is made from the front hub of a mountain bike just as it is also done for the VIRYA-1. However, the VIRYA-1.25AF generator has a steel stator disk which gives it a higher maximum torque level and a higher maximum power than for the synthetic stator disk of the VIRYA-1 generator. The VIRYA-1.25AF has a stainless steel rotor with a diameter of 1.25 m. This is really a simple design with an acceptable power curve.
The manual of VIRYA-2.2 is replaced by the manual of the VIRYA-1.81. The VIRYA-2.2 had a steel stator disk and it was expected that the heat generation in this sheet could be too high at high rotational speeds. The VIRYA-1.81 makes use of the same magnets but has a synthetic stator disk and no heat will be dissipated in this disk. As the maximum torque level for a synthetic stator sheet is lower than for a steel stator disk, the rotor diameter is reduced from 2.2 m up to 1.81 m. The design report of the VIRYA-2.2 with report number KD 607 is cancelled and replaced by the design report of the VIRYA-1.81 with report number 631.
A new chapter 6 has been added to public report KD 595 in which measurements on a Chinese axial flux generator are given. The generator has been tested in combination with the stainless steel VIRYA-1.65 rotor from September 2015 up to March 2017. The windmill worked well but the rotor was too noisy. A new more silent rotor with wooden blades is designed in report KD 630 (not public).
The note “A staff notation without flats and sharps”, which can be found at the menu “No wind energy”, is devided into four chapters. Chapter 4 is new and describes a very compact new staff notation for which all twelve chromatic tones in an octave have an unequivocal name and with which it is possible to write eight octaves at two identical staffs.
De notitie “Een notenschrift zonder mollen en kruizen”, die staat onder het menu “No wind energy”, is onderverdeeld in vier hoofdstukken. Hoofdstuk 4 is nieuw en beschrijft een zeer compact nieuw notenschrift waarvoor alle twaalf chromatische tonen in een octaaf een eenduidige naam hebben en waarmee het mogelijk is om acht octaven vast te leggen op twee identieke notenbalken.
At page 7 of KD 490: “Water pumping with a windmill” a short piece has been added about report KD 624 in which an alternative 46-pole PM-generator of the VIRYA-6.5 is described.