Frequency converter for supplying an electrodeless discharge lamp
First Claim
1. A frequency converter for energizing an electrodeless discharge lamp at a frequency of at least 0.5 MHz comprising, two input terminals adapted to be connected to a direct voltage source, means connecting the two input terminals to a first series arrangement of a power MOS-FET semiconductor switching element having a control electrode, a first coil, and a parallel arrangement of at least a first branch comprising a second coil and a branch comprising at least a capacitor, the second coil being coupled to the discharge path of the lamp in the operating condition of the lmap, a transformer having a primary and a secondary winding, means connecting said secondary winding to the control electrode and to a main electrode of the controlled semiconductor switching element, means connecting the primary winding of the transformer so that it forms part of the parallel arrangement, and means connecting a breakdown element in parallel with a winding of the transformer, the transformation ratio of the transformer being sufficiently large so that in the operating condition the voltage across the breakdown element reaches the breakdown value.
1 Assignment
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Accused Products
Abstract
A frequency converter for supplying an electrodeless discharge lamp comprises a VMOS controlled semiconductor switching element and a parallel circuit including an electric coil coupled to a discharge path of the lamp. A control circuit of the switching element includes a transformer which, in combination with two Zener diodes, results in a low-loss control circuit for the VMOS and, hence, an increased system efficiency.
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Citations
7 Claims
- 1. A frequency converter for energizing an electrodeless discharge lamp at a frequency of at least 0.5 MHz comprising, two input terminals adapted to be connected to a direct voltage source, means connecting the two input terminals to a first series arrangement of a power MOS-FET semiconductor switching element having a control electrode, a first coil, and a parallel arrangement of at least a first branch comprising a second coil and a branch comprising at least a capacitor, the second coil being coupled to the discharge path of the lamp in the operating condition of the lmap, a transformer having a primary and a secondary winding, means connecting said secondary winding to the control electrode and to a main electrode of the controlled semiconductor switching element, means connecting the primary winding of the transformer so that it forms part of the parallel arrangement, and means connecting a breakdown element in parallel with a winding of the transformer, the transformation ratio of the transformer being sufficiently large so that in the operating condition the voltage across the breakdown element reaches the breakdown value.
- 6. A frequency converter for operation of an electrodeless discharge lamp comprising, two input terminals for connection to a source of DC voltage, an FET transistor having a control electrode, means coupling said two input terminals to a series circuit including said FET transistor, a first inductor, and a parallel circuit comprising a second inductor and a capacitor, said second inductor being adapted to be coupled to a discharge path of said lamp, a substantially resistance-free control circuit for said transistor comprising a transformer having a primary winding connected to form a part of said parallel circuit and a secondary winding coupled to the control electrode and to a main current path electrode of the FET transistor so as to switch the transistor on and off at a very high frequency, and a voltage breakdown element coupled across one of said transformer windings and operative to limit the control voltage applied to the control electrode of the FET during operation of the frequency converter.
Specification