Soft-switching power converter for operation in discrete pulse modulation and pulse width modulation modes
First Claim
1. An ac-to-dc power converter, comprising:
- a rectifier for receiving an input ac voltage and converting said input ac voltage to a first dc voltage;
a boost converter circuit for receiving said first dc voltage and converting said first dc voltage to a second dc voltage across a dc link which is higher than said first dc voltage, said boost converter circuit having a filter inductor connected in series with a boost diode and further having a boost switching device coupled to the junction between said filter inductor and said boost diode, said boost switching device having an additional diode connected in antiparallel therewith;
a resonant circuit comprising a resonant inductor and a resonant capacitor coupled to said boost converter circuit;
clamping means coupled across said resonant inductor for limiting the voltage across said dc link to a predetermined maximum level, said clamping means comprising a clamp switching device connected in antiparallel with a clamp diode and further comprising a clamp capacitor connected in parallel with said clamp switching device and said clamp diode, said clamp capacitor being precharged to a predetermined voltage;
resonant control means for controlling the switching instants of said clamp switching device so as to cause stable oscillations of said resonant circuit such that the voltage across said dc link is zero at least once during each oscillation, said clamp switching device being turned on and off in a substantially lossless manner; and
ac current modulation means for receiving an input ac current and modulating said current by controlling the switching instants of said boost switching device in a substantially lossless manner.
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Accused Products
Abstract
A single-phase, soft-switching, ac-to-dc power converter comprises a rectifier for receiving and rectifying an ac voltage and providing the rectified ac voltage to a boost dc-to-dc converter, which in turn is coupled to an active clamped resonant dc link (ACRDCL). Resonant oscillations of the resonant dc link circuit comprising an inductor and a capacitor are maintained via control of an active clamp switching device. Soft-switching in a discrete pulse modulation scheme is achieved by controlling the switching instants of a boost switching device to occur at zero voltage instants of the resonant dc link. Alternatively, if a pair of snubber capacitors are added to the boost converter, soft-switching may be achieved in a pulse width modulation mode, resulting in reduced subharmonics even at higher frequencies and with smaller filter components.
61 Citations
17 Claims
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1. An ac-to-dc power converter, comprising:
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a rectifier for receiving an input ac voltage and converting said input ac voltage to a first dc voltage; a boost converter circuit for receiving said first dc voltage and converting said first dc voltage to a second dc voltage across a dc link which is higher than said first dc voltage, said boost converter circuit having a filter inductor connected in series with a boost diode and further having a boost switching device coupled to the junction between said filter inductor and said boost diode, said boost switching device having an additional diode connected in antiparallel therewith; a resonant circuit comprising a resonant inductor and a resonant capacitor coupled to said boost converter circuit; clamping means coupled across said resonant inductor for limiting the voltage across said dc link to a predetermined maximum level, said clamping means comprising a clamp switching device connected in antiparallel with a clamp diode and further comprising a clamp capacitor connected in parallel with said clamp switching device and said clamp diode, said clamp capacitor being precharged to a predetermined voltage; resonant control means for controlling the switching instants of said clamp switching device so as to cause stable oscillations of said resonant circuit such that the voltage across said dc link is zero at least once during each oscillation, said clamp switching device being turned on and off in a substantially lossless manner; and ac current modulation means for receiving an input ac current and modulating said current by controlling the switching instants of said boost switching device in a substantially lossless manner. - View Dependent Claims (2, 3, 4)
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5. An ac-to-ac power converter, comprising:
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a rectifier for receiving an input ac voltage and converting said input ac voltage to a first dc voltage; a boost converter circuit for receiving said first dc voltage and converting said first dc voltage to a second dc voltage across a dc link which is higher than said first dc voltage, said boost converter circuit having a filter inductor connected in series with a boost diode and further having a boost switching device coupled to the junction between said filter inductor and said boost diode; a resonant circuit comprising a resonant inductor and a resonant capacitor coupled to said boost converter circuit; clamping means coupled across said resonant inductor for limiting the voltage across said dc link to a predetermined maximum level, said clamping means comprising a clamp switching device connected in antiparallel with a clamp diode and further comprising a clamp capacitor connected in parallel with said clamp switching device and said clamp diode, said clamp capacitor being precharged to a predetermined voltage; resonant control means for controlling the switching instants of said clamp switching device so as to cause stable oscillations of said resonant circuit such that the voltage across said dc link is zero at least once during each oscillation, said clamp switching device being turned on and off in a substantially lossless manner; and ac current modulation means for receiving an input ac current and modulating said current by controlling the switching instants of said boost switching device in a substantially lossless manner; and inverter means including a plurality of inverter switching devices coupled to said dc link for receiving said second dc voltage and converting said second dc voltage to an output ac voltage. - View Dependent Claims (6, 7, 8, 9, 10)
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11. A dc-to-dc power converter, comprising:
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a boost converter circuit for receiving a first dc voltage and converting said first dc voltage to a second dc voltage across a dc link which is higher than said first dc voltage, said boost converter circuit having a filter inductor connected in series with a boost diode and further having a boost switching device coupled to the junction between said filter inductor and said boost diode, said boost switching device having an additional diode connected in antiparallel therewith; a resonant circuit comprising a resonant inductor and a resonant capacitor coupled to said boost converter circuit; clamping means coupled across said resonant inductor for limiting the voltage across said dc link to a predetermined maximum level, said clamping means comprising a clamp switching device connected in antiparallel with a clamp diode and further comprising a clamp capacitor connected in parallel with said clamp switching device and said clamp diode, said clamp capacitor being precharged to a predetermined voltage; resonant control means for controlling the switching instants of said clamp switching device so as to cause stable oscillations of said resonant circuit such that the voltage across said dc link is zero at least once during each oscillation, said clamp switching device being turned on and off in a substantially lossless manner; and ac current modulation means for receiving an input ac current and modulating said current by controlling the switching instants of said boost switching device in a substantially lossless manner. - View Dependent Claims (12, 13, 14)
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15. A power converter, comprising:
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a resonant circuit including a resonant inductor and a resonant capacitor for receiving an input dc voltage and for providing a resonant voltage across a dc link coupled thereto; clamping means coupled across said resonant inductor for limiting the voltage across said dc link to a predetermined maximum level, said clamping means comprising a clamp switching device connected in antiparallel with a clamp diode and further comprising a clamp capacitor connected in parallel with said clamp switching device and said clamp diode, said clamp capacitor being precharged to a predetermined voltage; resonant control means for controlling the switching instants of said clamp switching device so as to cause stable oscillations of said resonant circuit such that the voltage across said dc link is zero at least once during each oscillation, said clamp switching device being turned on and off in a substantially lossless manner; inverter means including a plurality of switching devices for receiving the resonant voltage across said dc link and converting said resonant voltage to an output ac voltage; snubber means comprising a snubber capacitor coupled in parallel with each of said switching devices for ensuring substantially lossless switching of said switching devices when they are turned off; and pulse width modulation means for controlling the switching instants of said switching devices to operate in a pulse width modulation mode with substantially zero switching losses, said switching devices being turned on only when said resonant voltage is substantially equal to zero and being turned off only when the current therethrough reaches a predetermined current reference level. - View Dependent Claims (16, 17)
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Specification