Articles for december 2016

Manual of a 27.6 V, 200 W battery charge controller added

The following document has been added at the bottom of the menu KD-Reports: “Manual of a 27.6 V, 200 W battery charge controller”. This manual describes a battery charge controller with a separate voltage controller and dump load. The dump load contains two 100 W resistors and a heavy Darlington transistor placed on an aluminium cooling plate size 3 * 250 * 500 mm. This battery charge controller can be used for 24 V battery charging windmills with a maximum power of 200 W. A larger dump load can be made if more 200 W modules are connected in parallel.

KD 614 reviewed

A new chapter 11 has been added to report KD 614. In chapter 11 it is investigated if it is possible to limit the maximum rotational speed by using an eddy-current brake at the back side of the generator. Another option might be to limit the phase voltage up to 240 V by using a voltage controller and dump load.

KD 622 reviewed

Chapter 9.6 and 9.7 have been added to report KD 622. Chapter 9.6 gives the calculation of the aerodynamic moment if the blade axis is shifted more to the nose. This has as advantages that the aerodynamic moment becomes larger and so the influence of the friction moment of the bearings becomes relatively smaller. It has also as advantage that the system reacts more sensible to wind gusts. Chapter 9.7 gives the geometry calculation of the compression spring.

KD 622 added

This new report Report KD 622 has as tittle: “Ideas about a pitch control mechanisme for the 2-bladed rotor of the VIRYA-5 windmill meant for connection to a 34-pole PM-generator for driving an asynchronous motor of a centrifugal pump. Description of the 34-pole generator”. The VIRYA-5 has already been described in report KD 614 but this first version of the VIRYA-5 is equipped with the hinged side vane safety system which is used in all other VIRYA windmills. However, this safety system makes use of the rotor thrust and it might be that the rotational speed isn’t limited sharp enough to prevent too high rotational speeds of the pump and too high frequencies of the pump motor. For the pitch control system, as described in report KD 622, it is expected that the maximum rotational speed is limited more sharply. The safety system described in KD 622 is rather simple as it uses only the aerodynamic pitch moment and there is no synchronisation mechanism in between both blades. Therefore it is expected that manufacture in developing countries is possible.