摘要:
A power converter topology operates as a switching capacitor (capacitive voltage divider) converter during a first, preferably short portion of a switching cycle to provide excellent dynamic transient response and as a pulse width modulated converter during a second portion of a switching cycle to provide flexibility of voltage regulation and generality of application. This topology can be made self-driven and is capable of zero voltage switching. Therefore the power converter can be used as one of a plurality of branches of a multi-phase converter to enhance transient response. The respective branches can also be independently optimized for particular load levels and can be operated independently in a phase shedding manner to improve efficiency at low load. Further, the power converter or respective branches of a multi-phase power converter are compatible with non-linear control to further improve dynamic response.
摘要:
A power converter topology operates as a switching capacitor (capacitive voltage divider) converter during a first, preferably short portion of a switching cycle to provide excellent dynamic transient response and as a pulse width modulated converter during a second portion of a switching cycle to provide flexibility of voltage regulation and generality of application. This topology can be made self-driven and is capable of zero voltage switching. Therefore the power converter can be used as one of a plurality of branches of a multi-phase converter to enhance transient response. The respective branches can also be independently optimized for particular load levels and can be operated independently in a phase shedding manner to improve efficiency at low load. Further, the power converter or respective branches of a multi-phase power converter are compatible with non-linear control to further improve dynamic response.
摘要:
Light load efficiency of a power factor correction circuit is improved by adaptive on-time control and providing for selection between a continuous conduction mode and a discontinuous conduction mode wherein the discontinuous conduction mode increases time between switching pulses controlling connection of a cyclically varying voltage to a filter/inductor that delivers a desired DC voltage and thus can greatly reduce the switching frequency at light loads where switching frequency related losses dominate efficiency. The mode for controlling switching is preferably selected for each switching pulse within a half cycle of the cyclically varying input voltage. A multi-phase embodiment allows cancellation of EMI noise at harmonics of the switching frequency and adaptive change of phase angle allows for cancellation of dominant higher order harmonics as switching frequency is reduced.
摘要:
Improved regulation and transient response are provided by a power supply architecture providing both unregulated and regulated voltage converters in parallel but deriving input power from separate power supplies connected in series wherein regulated and unregulated branches each provide a substantially fixed and constant proportion of the output current. The series connection of input power sources may provide a further feedback mechanism in addition to feedback for regulation which enhances overall performance. As a perfecting feature of the invention, inductor-less resonant converters which are switched in an interleaved fashion may be used in the unregulated branch while substantially cancelling the characteristic large output voltage ripple thereof.
摘要:
A multiple phase buck converter or boost converter, or buck-boost converter has an inductor in each phase. The inductors are inversely coupled. In a first embodiment, the converter includes a toroidal magnetic core with inductors extending under and over opposite sides of the toroidal magnetic core. The coupled inductors are thereby inversely coupled and have a relatively low ohmic resistance. In a second embodiment, the converter comprises a ladder-shaped magnetic core (i.e. having parallel sides, and connecting rungs). In this case, the inductors extend under the sides, and over the rungs. Each inductor is disposed over a separate rung. The ladder-shaped magnetic core is preferably disposed flat on a circuit board. Inverse coupling and low ohmic resistance are also provided in the second embodiment having the ladder structure.
摘要:
An active linear regulator circuit in parallel with a filter capacitor of a switching voltage regulator injects current to a load only when the switching regulator and capacitor cannot supply adequate current to follow high frequency load transients in a manner which is compatible with adaptive voltage positioning (AVP) requirements. control of current injection and determination of the insufficiency of current from the switching regulator and capacitors is achieved by impedance matching of the linear regulator to the switching regulator. The linear regulator thus operates at relatively low current and duty cycle to limit power dissipation therein. By matching impedances and increasing the bandwidth of the switching regulator, filter capacitor requirements can be reduced to the point of being met entirely by packaging and/or on-die capacitors which may be placed close to or at the point of load to reduce parasitic inductance, as can the linear regulator.
摘要:
In a power converter having m=two or more channels of power factor correction (PFC) circuits connected in parallel and an electromagnetic interference (EMI) filter connected in series therewith, phase shifts in switching between the respective PFC channels can allow increase of EMI filter corner frequency allowing reduction of size and cost of the EMI filter at some switching frequencies. Asymmetrical phase shifts (other than 360°/m) such as 360°/2m and other phase shifts and variations in m allow increase of EMI filter corner frequency at switching frequencies where symmetrical, 360°/m phase shifts provide no benefit to EMI filter design by providing cancellation or partial cancellation of different harmonics of the switching noise; which cancellation may be arranged to be complementary to the EMI filter function at more than one peak of the noise spectrum. (Such asymmetrical phase shifts do not significantly increase ripple and consequent switching noise). Alteration of m and corresponding alteration of phase shift may be performed adaptively for purposes of improving efficiency at light loads and the like.
摘要:
Power converters having reduced body diode conduction loss, reduced reverse recovery loss and lower switching noise, among other benefits, have a resonant capacitor Cr connected across an unfiltered output. The resonant capacitor Cr resonates with the leakage inductance Lk of the transformer. The resonant capacitor and leakage inductance are selected such that ½ a LC resonance period is equal to an ON time of each secondary switch S1 S2. The resonance provides zero current switching for secondary switches S1 S2, eliminates zero body diode conduction during dead times, and eliminates reverse recovery losses in the secondary switches. The present invention is applicable to many different circuit topologies such as full bridge, active clamp forward, push-pull forward, and center-tap secondary. The present converters provide high energy conversion efficiency and high frequency operation.
摘要翻译:具有降低的体二极管导通损耗,降低的反向恢复损耗和较低开关噪声以及其他益处的功率转换器具有连接在未滤波输出端的谐振电容器Cr。 谐振电容器Cr与变压器的漏电感Lk共振。 谐振电容器和漏电感被选择为使得LC共振周期的1/2相当于每个次级开关S 1 S 2的导通时间。 谐振为次级开关S 1 S 2提供零电流开关,在死区时间消除零体二极管导通,并消除次级开关中的反向恢复损耗。 本发明可应用于许多不同的电路拓扑,例如全桥,有源钳前进,推挽前进和中心抽头次级。 本转换器提供高能量转换效率和高频操作。
摘要:
A two-stage power converter that dynamically adjusts to output current requirements includes a first stage regulator that provides power to a second stage regulator. The first stage can be a buck converter, and the second stage can be a multiple-phase buck converter. The output voltage of the first stage (intermediate bus voltage Vbus) is varied according to the load current to optimize conversion efficiency. To provide maximum efficiency, the Vbus voltage is increased as load current increases. The Vbus voltage provided by the first stage can be varied by duty cycle or operating frequency control. In another embodiment, the switching frequency of the second stage is varied as output current changes so that output current ripple is held constant. In an embodiment employing a multiple-phase buck converter in the second stage, the number of operating phases are varied as output current changes.
摘要:
Buck converters having a resonant inductor Lr, resonant capacitor Cr, and synchronous switch Q3 that together provide reduced switching loss and soft switching. In operation, the resonant inductor Lr is charged during a time period A. Then, Lr is freewheeling and provides current to an output inductor Lo. Then, Q3 is turned OFF, and energy from the resonant inductor Lr charges the resonant capacitor Cr. Finally, energy from the resonant capacitor Cr is provided to the output inductor and load. The output power can be adjusted by phase control of the operation of switch Q3. In alternative embodiments, the circuit has a pair of coupled inductors L1 L2 or an isolation transformer 40. The coupled inductors have a polarity selected so that the output voltage is reduced, thereby allowing top switch Q1 to have a greater duty cycle. These circuits feature no body diode loss in the switch Q3.