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US 6,477,062 B1Granted
Power supply unit including an inverter
AssigneeKoninklijke Philips Electronics N.V.
InventorsBernhard Wagner, Olaf Märtens
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AssigneeKoninklijke Philips Electronics N.V.
InventorsBernhard Wagner, Olaf Märtens
Estimating the term…
The invention relates to a power supply unit with an inverter which co-operates with a resonant circuit (L, C) and can be controlled so as to adjust the output power by means of a control unit (6). The power supply unit is characterized notably by the fact that it is formed by a first and a second switching unit (S1, S4; S2, S3) whereby a voltage of a first polarity can be applied to the resonant circuit (L, C) in a first switching state and a voltage of a second polarity can be applied thereto in a second switching state, the switching states being switchable by the control unit (6) in such a manner that in a first mode of operation for low output powers the output power can be adjusted by changing the duration of the switching states at an essentially constant switching frequency fs which is at least a predetermined factor lower than the resonance frequency fres of the resonant circuit, and that in a second mode of operation for high output powers the output power can be adjusted by changing the switching frequency in the range of the resonance frequency.
A power supply unit which includes an inverter which co-operates with a series resonant circuit that is directly connected to a bridge rectifier and can be controlled by means of a control unit so as to adjust the output power, wherein the inverter is formed by a first switching unit and a second switching unit, each switching unit being in parallel with a diode and being directly connected to a first power supply and the series resonant circuit, whereby a voltage of a first polarity can be applied to the series resonant circuit in a first switching state whereas a voltage of a second polarity can be applied thereto in a second switching state, which switching states can be switched by the control unit in such a manner that in a first mode of operation for low output powers the output power can be adjusted by changing the duration of the switching stage at an essentially constant switching frequency fs which is at least a predetermined factor lower than the resonance frequency fres of the resonant circuit, and that in a second mode of operation for high output powers the output power can be adjusted by changing the switching frequency in the range of the resonance frequency.
Dependencies are inferred from the claim text.