EP0217427A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Switched-mode power supply circuit including a power switch
Assignee: Koninklijke Philips NV
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Filing: 1986-08-04
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Granted: —
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Expires: 2006-08-04
Abstract
Abstract A switched-mode power supply circuit for converting a d.c. input voltage into a d.c. output voltage. The circuit includes a controllable power switch (Tr1) arranged in series with the primary winding (L1) of a transformer (T), which winding forms part of a resonant circuit. To reduce the losses caused by turning on of the switch the drive path of the switch incorporates a delay network (R11, C9) for each time delaying this turn-on until an instant which is substantially half a cycle of the resonance frequency later than the initial instant of the decrease of the voltage across the switch during its previous cut-off time.
Inventors
- 👤 Antonius Adrianus Maria Marinus
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 23:22
CPC Classifications
H; H02; H02M; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H02M3/338; H02M3/3385; Y; Y02; Y02B; Y02B70/00; Y02B70/10
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
208 words
A switched-mode power supply circuit for converting a d.c. input voltage into a d.c. output voltage, including a controllable power switch arranged in series with the primary winding of a transformer, the series arrangement thus formed being coupled to the input voltage terminals, said transformer having a secondary winding to which a rectifier is coupled for providing the output voltage, the primary winding forming part of a resonant circuit when switch and rectifier pass no current, a drive circuit including a delay network being connected to a control electrode of the switch for each time initiating turning off of the switch, whereafter the voltage across the switch increases to a given value and substantially maintains said value, whereafter the said voltage decreases in accordance with an oscillation with the resonance frequency, and for each time initiating turning on of the switch, whereafter the voltage across the switch is substantially zero, characterized in that the delay network is coupled to the control electrode of the power switch for each time adjusting the turning on of said switch at an instant which is substantially half a cycle of the resonance frequency later than the initial instant of the decrease of the voltage across the switch during its previous cut-off time.
Claim 2
Dependent Claim
208 words
A switched-mode power supply circuit for converting a d.c. input voltage into a d.c. output voltage, including a controllable power switch arranged in series with the primary winding of a transformer, the series arrangement thus formed being coupled to the input voltage terminals, said transformer having a secondary winding to which a rectifier is coupled for providing the output voltage, the primary winding forming part of a resonant circuit when switch and rectifier pass no current, a drive circuit including a delay network being connected to a control electrode of the switch for each time initiating turning off of the switch, whereafter the voltage across the switch increases to a given value and substantially maintains said value, whereafter the said voltage decreases in accordance with an oscillation with the resonance frequency, and for each time initiating turning on of the switch, whereafter the voltage across the switch is substantially zero, characterized in that the delay network is coupled to the control electrode of the power switch for each time adjusting the turning on of said switch at an instant which is substantially half a cycle of the resonance frequency later than the initial instant of the decrease of the voltage across the switch during its previous cut-off time.
Claim 3
Dependent Claim
34 words
A power supply switch as claimed in Claim 1, characterized in that the output signal of the delay network is a cut-off signal for the power switch after the cut-off instant of the rectifier.
Claim 4
Dependent Claim
96 words
A power supply circuit as claimed in Claim 1, in which the delay network is coupled to a control electrode of a second switch which is conducting at the end of the conducting period of the power switch for initiating the turn-off of said power switch, characterized by means for each time rendering the second switch conducting substantially at the initial instant of the decrease of the voltage across the power switch and for subsequently maintaining the second switch in the conducting state during substantially half a cycle of the resonance frequency after the said instant.
Claim 5
Dependent Claim
33 words
A power supply circuit as claimed in Claim 3, characterized in that the delay network is coupled to a third switch which is conducting for maintaining the second switch in the conducting state.
Claim 6
Dependent Claim
62 words
A power supply circuit as claimed in Claim 1, in which the delay network is connected to a further secondary winding of the transformer, characterized in that, during operation, the voltage at the junction of the delay network and the said further secondary winding has the same polarity as the voltage at the junction of the primary winding and the power switch.
Claim 7
Dependent Claim
46 words
A power supply circuit as claimed in Claim 5, characterized in that a series arrangement of two diodes having the same conductivity directions as the input diode of the third switch implemented as a transistor, is arranged in parallel with the output of the delay network.
Claim 8
Dependent Claim
102 words
A power supply circuit as claimed in Claim 4, characterized in that the drive circuit also includes a second delay network for each time initiating turning on of the power switch, said second delay network being connected to a point of a further secondary winding of the transformer, which point, during operation, carries a voltage having the opposite polarity with respect to the voltage at the junction of the primary winding and the power switch, the second delay network being coupled to the control electrode of the second switch via a fourth switch which is conducting for cutting off the power switch.
Claim 9
Dependent Claim
48 words
A power supply circuit as claimed in Claim 7, characterized in that a starting resistor is connected to the control electrode of the second switch and in that a control circuit for maintaining the output voltage substantially constant is connected to a control electrode of the fourth switch.
Claim 10
Dependent Claim
41 words
A power supply circuit as claimed in Claim 4, characterized in that a diode is arranged in series with the third switch in the drive path of the second switch, said diode having the same conductivity direction as the third switch.
References Cited (Backward Citations)
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