Bitte wählen Sie ihr Lieferland und ihre Kundengruppe
Generators with permanent-magnet excitation are usually restricted in output power capability by voltage regulation. The maximum power which can be delivered to a resistive load is proportional to speed and may be much less than the thermal rating. To make effective use of the armature rating or to provide an adequate peak torque margin, it may be necessary either to increase the excitation or to reduce the series inductance. The approach adopted was to employ a capacitor connected across the generator terminals effectively to de-tune part of the series inductance. This may be viewed alternatively as providing additional excitation due to the capacitive current flowing in the stator coils. In operation with rectified output, the capacitor allows energy to be stored in the inductor during the non-conduction period of the diode rectifier and then the current is suddenly transferred to the dc side when the rectifier begins to conduct, thus the conduction period begins with substantial current which greatly increases the total current delivered to the dc load. The paper presents an analysis of the simple system and offers guidelines for the choice of capacitance. An improved model taking account of rectifier loading is developed. Results are compared with tests on a laboratory machine and the performance of a typical full-scale machine is set out showing the importance of the correct selection of capacitance.