Multi-resonant converter power supply

Abstract

In one embodiment, an apparatus includes a first stage including a first active switch, a first resonant inductor, and a resonant capacitor, and a second stage including a second active switch, a second resonant inductor, and a filter capacitor. The first and second stages form a non-isolated multi-resonant converter for converting a DC input voltage to a DC output voltage.

Description

Technical Field

[0001] The present disclosure relates generally to voltage converters and, more particularly, to multi-resonant converters. Background Art

[0002] A DC-to-DC converter is used to convert a DC voltage at one level to a DC voltage at another level and deliver power to a load. Such converters typically include a transformer, which acts as a voltage converter to provide power transfer from input to output. The transformer also provides galvanic isolation between the input and output in most applications. In traditional resonant topologies, a transformer is typically required for a wide voltage conversion range from input to output to achieve good efficiency. However, the use of a converter limits the switching frequency due to core losses at higher frequencies and has additional disadvantages such as complex circuitry, large size, and high cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Figure 1 An example of a step-down multi-resonant converter (MRC) is illustrated according to one embodiment.

[0004] Figure 2 Pictured Figure 1 The operation of MRC is shown in .

[0005] Figure 3 An example of a high voltage ratio step-down MRC is illustrated according to one embodiment.

[0006] Figure 4 Pictured Figure 3 The operation of MRC is shown in .

[0007] Figure 5 The diagram shows the power storage and power transfer stages. Figure 3 Additional details of the operation of the MRC are shown in .

[0008] Figure 6 An example of an MRC step-down-step-up type buck-boost is illustrated according to one embodiment.

[0009] Figure 7 Pictured Figure 6 The operation of MRC is shown in .

[0010] Figure 8A An example of an MRC step-up-step-down type boost-buck is illustrated according to one embodiment.

[0011] Figure 8B An example of an MRC step-up type boost-buck is illustrated according to one embodiment.

[0012] Figure 9is a block diagram illustrating an implementation of an MRC as a point-of-load power supply on a line card or fabric card, according to one embodiment.

[0013] Figure 10 The diagram shows the AC / DC PFC (Power Factor Correction) MRC stage in an isolated DC / DC converter. Figure 6 An example of an implementation of an MRC topology.

[0014] Figure 11A The diagram shows a DC / DC isolation MRC with a forward converter transformer stage. Figure 1 An example of an implementation of a step-down MRC topology.

[0015] Figure 11B The diagram shows a DC / DC isolation MRC with a forward converter transformer stage. Figure 6 An example of an implementation of a step-up MRC topology structure.

[0016] Figure 12A and 12B is an example illustrating an implementation of an isolated MRC for a flyback PWM with a resonant capacitor and a second resonant switching stage with a synchronous rectifier.

[0017] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0018] Overview

[0019] Various aspects of the invention are recited in the independent claims and preferred features are recited in the dependent claims. Features of one aspect may be applied individually to each aspect or in combination with other aspects.

[0020] In one embodiment, an apparatus generally includes a first stage including a first active switch, a first resonant inductor, and a resonant capacitor, and a second stage including a second active switch, a second resonant inductor, and a filter capacitor. The first and second stages form a non-isolated multi-resonant converter topology for converting a DC input voltage to a DC output voltage.

[0021] The non-isolated multi-resonant converter may include a step-down converter or a step-up converter. In one or more embodiments, one or both stages include synchronous rectifiers. In one or more embodiments, the first and second resonant inductors operate with current in discontinuous mode and the voltage at the resonant capacitor discharges to zero over each of a plurality of cycles. In one or more embodiments, both stages operate in discontinuous current mode with zero current on, the first stage operates with zero current off at maximum duty cycle, and the second stage operates with zero current off at ninety degrees of a half-sine transfer pulse current. In one or more embodiments, the first stage is configured to regulate the charge stored on the resonant capacitor using pulse width modulation or frequency modulation to regulate the output voltage and current. In one or more embodiments, the second resonant inductor includes a tapped inductor.

[0022] In another embodiment, an apparatus generally includes a card for insertion into a network device, the card including a point-of-load power supply, the point-of-load power supply including a first stage including a first switch, a first inductor, and a resonant capacitor, and a second stage including a second switch, a second inductor, and a filter capacitor. The first stage includes a power conditioning resonant stage, and the second stage includes a voltage converter stage to form a non-isolated multi-resonant converter.

[0023] In another embodiment, an apparatus generally includes a point-of-load power supply including a first stage including a first active switch, a resonant inductor, and a resonant capacitor, and a second stage including a second active switch, a tapped resonant inductor, and a filter capacitor. The first stage and the second stage form a non-isolated multi-resonant converter for converting a DC input voltage to a DC output voltage using a step-down voltage conversion having a large input-to-output ratio, such as 48 volts to 1 volt, or a step-up voltage conversion having a large input-to-output ratio, such as 48 volts to 400 volts.

[0024] A further understanding of the features and advantages of the embodiments described herein may be realized by reference to the remaining portions of the specification and drawings.

[0025] Example Embodiments

[0026] The following description is presented to enable one of ordinary skill in the art to make and use the embodiments. The descriptions of specific embodiments and applications are provided as examples only, and various modifications will be apparent to those skilled in the art. The general principles described herein may be applied to other applications without departing from the scope of the embodiments. Thus, the embodiments are not limited to those shown, but are intended to conform to the widest range consistent with the principles and features described herein. For the sake of clarity, details related to technical materials known in the technical field related to the embodiments have not been described in detail.

[0027] One or more embodiments described herein provide a two-stage, two-switch, multi-resonant voltage converter that is operable to provide a wide range (high voltage conversion ratio) input to output voltage, step up or step down, without the need for a transformer to achieve higher frequencies, and with high efficiency with fewer components, smaller space requirements, and lower cost. As described in detail below, the topology combines a resonant or quasi-resonant first stage for power regulation and a second stage as a voltage converter to achieve a wide voltage conversion range with high efficiency. In one or more embodiments, the topology can provide a DC / DC non-isolated power supply comprising a two-stage, two-switch multi-resonant converter (MRC) with quasi-resonant or full-resonant operation in one or both stages, providing voltage conversion with high efficiency over a wide voltage ratio for up-conversion or down-conversion.

[0028] The embodiments described herein provide higher frequencies and efficiencies with fewer components to achieve high power density. In one or more embodiments, higher efficiencies are provided with soft-switching resonant or quasi-resonant charging and discharging stages, and higher frequencies are provided without transformers typically required for high voltage ratio conversion of step-down or step-up converters. Soft switching in most phases provides high efficiency and lower stress on switches and components.

[0029] As previously described, one or more embodiments provide a large voltage conversion ratio as a down converter or up converter without a transformer or performance loss. Thus, a high voltage ratio step-down or step-up converter can be implemented using the embodiments described herein without the need for a transformer. By eliminating the need for a transformer for wide voltage conversion, very high frequencies can be used with a smaller size package and higher efficiency. In one or more embodiments, the converter provides flexible voltage or current regulation, including pulse width modulation (PWM), frequency modulation (FM), or both pulse width modulation and frequency modulation.

[0030] Now referring to the drawings, first Figure 1 , an example of a multi-resonant converter (MRC) power supply circuit, generally designated 10, is shown according to one embodiment. Figure 1 In the example shown, the MRC 10 is a two-stage, two-switch resonant-buck-buck converter. The first stage 9 includes a first active switch 12 (Q1), a first resonant inductor 13 (L R1 ), resonant capacitor 14 (C R) and a first synchronous rectifier 15 (Q2). The second stage 11 includes a second active switch 16 (Q3), a second resonant inductor 17 (L R2 ), filter capacitor 18 (C F ) and the second synchronous rectifier 19 (Q4). DC input voltage V in (DC voltage source) is converted into a DC output voltage to be applied to the L The first inductor L R1 With the first switch Q1 and the resonant capacitor C R The second inductor L is electrically coupled in series. R2 With the second switch Q3 and the filter capacitor C F The synchronous rectifiers Q2 and Q4 are electrically coupled in series with the capacitor C R and C F Resistor R L With capacitor C F As described in detail below, the input LC charge storage stage (first stage 9) to the output voltage conversion stage (second stage 11) to the output capacitor C F and load R L The first and second stages form a non-isolated multi-resonant converter for converting a DC input voltage into a DC output voltage.

[0031] Switches Q1 and Q3 and synchronous rectifiers Q2 and Q4 may include any suitable actively controlled switching devices (active switches) capable of operating at a desired switching frequency, such as metal oxide semiconductor field effect transistors (MOSFETs), bipolar junction transistors (BJTs), gallium nitride field effect transistors (GaNFETs), or solid state relays (SSRs). The closing and opening of the switches may be managed by control logic coupled to the switches (not shown). The control logic may be part of a processor or a separate integrated circuit, such as a pulse width modulation (PWM) controller. Figure 1 The voltage step-down for the illustrated MRC topology may be, for example, 50 volts to 25 volts (50:25V) or other suitable ratio.

[0032] MRC 10 generally takes the input voltage V in The energy voltage charge stored in C R, and transfers the energy charge to the output filter and the load, its power transfer function is P in =1 / 2C R V CR 2 F, where P in is the input power, V CR is the peak voltage charge of the capacitor, C R is the resonant capacitor, and F is the switching frequency. The first LC resonant stage switch Q1 is used to switch the input voltage V in The stored power pulse on the resonant capacitor C R Charge as follows Figure 2 The second LC resonant stage switch Q3 then acts as a voltage converter at the output filter capacitor C F and load R L The resonant capacitor C is transferred at high frequencies R The resonant inductor current is usually operated in discontinuous mode, and the resonant capacitor voltage is discharged to a minimum voltage of zero in each cycle with discontinuous current operation (see Figure 2 V in CR This may require adjusting or modulating the duty cycle of the second stage discharge switch to a switching period less than 90 degrees. However, there are other possible control modes where C R The minimum voltage on each switching cycle is above or below zero, with discontinuous or continuous current operation, where the second stage discharge switch duty cycle can be adjusted to greater than or less than 90 degree switching cycle, and the synchronous rectifier can be eliminated.

[0033] To understand Figure 1 The MRC power supply topology shown is only an example, and the circuit can be modified without departing from the scope of the embodiment. For example, one or both of the synchronous rectifiers Q2 and Q4 can be removed. In addition, the inductor L R2 The tapped inductor can be used instead, as shown below for Figure 3 The circuit can also be modified to provide step-up conversion, as shown below for Figure 8, Figure 10 A and Figure 10 B. Usually, C R The minimum voltage on the C is zero in each cycle in the case of discontinuous current operation, but in some control applications, this may require adjusting or modulating the duty cycle of the second stage discharge switch to a switching period of less than 90 degrees. However, there are other possible control modes in which C RThe minimum voltage on the MOSFET can be above or below zero during each switching cycle, with discontinuous or continuous current operation, wherein the duty cycle of the second stage discharge switch can be adjusted to be greater than or less than a 90-degree switching cycle, and the synchronous rectifier can be eliminated. Additionally, in one or more embodiments, the circuit can include an input isolation stage, and the input isolation stage can be part of the input switching stage.

[0034] Figure 2 Pictured Figure 1 The step-down MRC operation of the converter 10 is shown in FIG. Figure 2 The Q1 and Q3 traces in the diagram illustrate the on / off state of the switches. Figure 2 Q1 is a duty cycle power charging switch, and Q3 is a power transfer switch. Q2 and Q4 are synchronous rectifiers, where Q2 is only for Q1 Duty Cycle. (0-0.5) The modulation is synchronous rectifier. L R1 The voltage and current at LR1 and I LR1 . L R2 The voltage and current at LR2 and I LR2 . V CR The diagram shows C R The resonant capacitor C R At full duty cycle it will charge to V in The input switch Q1 is modulated to a resonant input charging cycle of 0-50% / cycle (duty cycle) with zero current turn-on switching to pass L R1 Current (I LR1 ) modulates C with 0-2 times input voltage R .

[0035] In this example, the first LC resonant switching stage 9 operates in a discontinuous current mode with zero current switch-on and zero current switch-off at a maximum duty cycle of 50% switching frequency as the resonant half-cycle ( Figure 1 and 2 The first LC switch resonant stage 9 can use pulse width modulation (PWM) at a duty cycle of 0-50% to regulate the current stored in the resonant capacitor C R The voltage charge on the resonant inductor is used to regulate the output voltage and current. During PWM switching, duty cycles less than 50% of the maximum duty cycle will cause the first resonant inductor to shut down by interrupting the current flow, using synchronous rectifiers. Another method of regulating the output voltage and current uses frequency modulation (FM) below the maximum resonant switching frequency. A combination of PWM and FM can also be used.

[0036] In this example, the second CL resonant switching stage 11 operates in discontinuous current mode with zero current turned on, but turns off at 90 degrees of the half-sine transfer pulse current, where the synchronous rectifier clamps the current back to the output filter capacitor C F and load R L The energy storage in the first 1 / 2 cycle and the energy transfer and voltage conversion in the second 1 / 2 cycle complete one power cycle at the switching frequency. The output switch Q3 is fixed to a resonant output discharge of 25% / cycle for 1 / 2 cycle with zero current turn-on switching, which turns L R2 The energy in the charging current is transferred to the filter capacitor (output capacitor) C F and load R L This allows C R All energy stored in is transferred to the output, allowing C R The voltage on the output inductor L remains at zero volts during the next charging cycle. R2 For example, L R2 Current (I LR2 ) 25% / cycle linear output discharge, charging to the output capacitor C F and load R L middle.

[0037] Below is Figure 1 The circuit shown in Figure 2 An example of the MRC power transfer function in operation is shown in:

[0038] Pin=1 / 2*C R *V CR 2 *F s

[0039] in:

[0040] C R = resonant capacitor;

[0041] V CR = capacitor peak charge voltage; and

[0042] F s =Switching frequency.

[0043] In one example, the input power is defined as follows:

[0044] Pin=Vin 2 *.637avg*Eff*D / Rin

[0045] =Vin 2 *.637avg*Eff*D / Z0

[0046] in:

[0047] Z0=(L R / C R )^ .5 ;

[0048] L R = resonant inductor;

[0049] C R = resonant capacitor; and

[0050] D = Duty Cycle

[0051] Resonant half period = 1 / (2*F) = 1 / (π*(L R / C R )^ .5 )

[0052] The first stage 9 is connected to the resonant capacitor C in the first half cycle of the switching period. R Energy storage is provided in . This energy represents the power input per cycle and can be modulated by PWM or FM as described above for output voltage and current regulation. The second stage 11 provides the power from the resonant capacitor C R To the output filter capacitor C F and the load resistor R L The second stage 11 is also a voltage conversion stage, acting as a voltage down-converter (or up-converter as described below), and is controlled by the output resistance. The output power can be defined as follows:

[0053] Pout=Pin*Eff

[0054] Vout=(Pout*R L )^ .5

[0055] V CR =2*Vin*sin(Duty (0-1) *90°)

[0056] in:

[0057] Duty (0-1) =T Q1_ON / 0.5T Fs_period

[0058] C R =Pout*maxDuty (0-0.5) *Eff / (.5*V CR 2 *Fs)

[0059] L R =(t R / π) 2 / CR )

[0060] where t R =Resonant half sine at 1 / 2Fs

[0061] C F =i*1 / Fs / dv

[0062] Where i = Iout; F s = switching frequency; and

[0063] dv=Vp-p ripple

[0064] Figure 3 The figure shows a DC / DC resonant-buck-buck high voltage ratio step-down MRC non-isolated power converter, generally represented as 30. In this example, the second-stage inductor L R2 Tapped inductor L R2 / L D Replace. L R2 It is the resonant choke that transfers the power voltage from the converter stage to the output filter capacitor and load resistor. D is the resonant choke L R2 The tapped inductor winding is used for the current reset period, with the Q4 synchronous rectifier reset linearly at lower output voltages. The split inductor provides a high voltage ratio, where L D The inductance is much smaller than L R2 inductance to allow L R2 The current reset period is shorter than the Q3 discharge period of 1 / 4 cycle. R2 On a higher voltage compared to L D The output voltage on the Figure 3 The illustrated DC / DC step-down MRC 30 provides a 48 volt to 1 volt ratio (48:1V), 50:5V, or any other suitable step-down POL converter high voltage ratio with high efficiency.

[0065] Figure 4 Pictured Figure 3 The step-down MRC operation of the converter 10 is shown in FIG. Figure 4 The Q1 and Q3 traces in the diagram illustrate the on / off state of the switches. Figure 2 Q1 is the duty cycle power charging, and Q3 is the power transfer. Q2 and Q4 are synchronous rectifiers, where Q2 is only for Q1 Duty Cycle (0-0.5) The modulation is synchronous rectifier. For L R1 Respectively in V LR1 and I LR1 The voltage and current are shown. R2 shows the current with respect to the synchronous rectifier Q4 at ILr2 And for L D in I LD . V CR The diagram shows C R charging and discharging at the.

[0066] The power and voltage can be calculated as previously for Figure 1 Described. D Can be defined as follows:

[0067] L D =e*1.5t R *.5 / di

[0068] in:

[0069] e=Vout;

[0070] di=Iout / (Duty (0-.25) *0.5, for the average value)

[0071] Figure 5 Pictured Figure 3 The power storage and voltage conversion stage in the MRC power topology shown has a duty cycle of 0-100% in the first 1 / 2 cycle. Modes 1 and 2 form the resonant charge power storage stage. Mode 1 illustrates the maximum duty cycle of the power storage, V in Enter L through Q1 R1 / C R To charge I LR1 Mode 2 covers the synchronous rectifier Q2 which switches I LR1 Discharge to C R Mode 3 and Mode 4 constitute the power transfer to the voltage conversion stage. Mode 3 illustrates the C R Go to L via Q3 R2 / C F resonant discharge to charge I LR2 . Mode 4 shows that L R2 / L D The linear discharge is discharged through the synchronous rectifier Q4. LR2 .

[0072] As previously mentioned, the MRC may also include a step-up converter. Figure 6 The figure shows an example of a DC / DC MRC two-switch, two-stage resonant-buck-boost step-down-step-up power supply that can be used as a voltage step-up or step-down converter, generally represented as 80. This topology allows simple, high-efficiency step-up voltage conversion with high voltage input-output ratios, such as 48:400V, 50:400V, or other suitable ratios (e.g., at least 48:400V). Figure 6In the example shown, the first stage includes a first switch 82 (Q1), a first resonant inductor 83 (L R1 ) and resonant capacitor 84 (C R The second stage includes a second resonant inductor 87 (L R2 ), the second switch 86 (Q3) and the filter capacitor 88 (C F In this example, each stage also includes synchronous rectifiers 85 (Q2), 89 (Q4).

[0073] Figure 7 Pictured Figure 6 The operation of a two-stage, two-switch step-up example MRC 80 is shown in FIG. The on / off cycles of the switches are shown for Q1 and Q3. Q1 is duty-cycle power charging, and Q3 is power transfer. Q2 and Q4 are synchronous rectifiers, with Q2 being a synchronous rectifier only for Q1 duty cycle 0-50% modulation.

[0074] Switch Q1 and inductor L R1 The voltage and current between the V LR1 and I LR1 . C R The charge and discharge voltages are shown at V CR . L R2 The voltage at V LR2 . L R2 and Q3 is shown at I LR2 / I Q3 And I LR2 and Q4 is shown at I LR2 / I Q4 .

[0075] Below is Figure 6 The circuit shown in Figure 7 An example power transfer function description of the corresponding operation is shown in .

[0076] Vout=(Pout*R L )^ .5

[0077] Pout=Pin*Eff=.5*C R *V CR 2 *Fs*Eff

[0078] V CR =2*Vin*sin(Duty (0-1) *90°)

[0079] in:

[0080] Duty (0-1) =TQ1_ON / 0.5T Fs_period

[0081] C R =Pout*Duty*Eff / (.5*V CR 2 *Fs)

[0082] L R1 =(tR / pi)2 / C R )

[0083] in:

[0084] Resonant half-sine at tR=1 / 2Fs

[0085] L R2 =e*(1.5tR*.5) / di

[0086] in:

[0087] e = Vout; and

[0088] di=Iout / (Duty*0.5, for average value)

[0089] C F =i*1 / Fs / dv

[0090] in:

[0091] i=Iout;

[0092] F s = switching frequency; and

[0093] dv=Vp-p ripple

[0094] Another example of a DC / DC resonant-boost-buck step-up-step-down MRC non-isolated (non-isolated) voltage converter with two switches and two synchronous rectifiers is shown in Figure 8A , and generally designated 100, which can be used as a voltage step-up or step-down converter. The circuit 100 includes a resonant inductor 103 (L R1 )、107(L R2 ), resonant capacitor 104 (C R ), filter capacitor 108 (C F ), switches 105 (Q1) and 106 (Q3) and synchronous rectifiers 102 (Q2) and 109 (Q4). The MRC 100 is configured to provide a higher stored charge voltage. An example of an MRC step-up boost-boost, generally designated 101, is shown in FIG. Figure 8B As shown in Figure 8B As shown in , the components in the second stage have been modified to change from buck to boost.

[0095] In one or more embodiments, the POL converter 110 according to one of the embodiments described herein may be used to replace a conventional IBC (Intermediate-Bus-Converter) and POL converter on a line card or fabric card 112, such as Figure 9 In one example, the POL converter 110 can be used to replace a standard 48:12 / 10V IBC plus 12 / 10V:1V POL converter with a 48:1V POL, while providing high efficiency, a small size, a low-cost package, and eliminating the size and frequency limitations of the transformer. Figure 9 In the example shown, the POL 110 receives power from a PSU (Power Supply Unit) 114 and provides power to one or more processors (eg, ASICs (Application Specific Integrated Circuits)), memory, or other chips or devices 116 .

[0096] It is important to understand that Figure 9 The implementation shown is just one example, and the POL can be used on any type of board or system type and power application, including, for example, LEDs, lasers, battery chargers, motors, fans, and so on.

[0097] The embodiments described herein may be implemented, for example, in a board mounted power (BMP) POL power supply, a BMP IBC power supply, a front end power (FEP) power factor converter (PFC) power supply section, an LLC type resonant power converter, a high voltage multiplier, a buck, a boost, a forward, a multi-phase stage, or any other suitable application.

[0098] exist Figure 10 In an example shown, Figure 6 The MRC topology may be incorporated for use in an AC / DC non-isolated PFC (power factor correction) MRC stage to an isolated DC / DC converter, generally designated 120. The circuit may include, for example, an AC input rectifier to an MRC two-stage buck-boost two-switch two-synchronous rectifier example as a step-up converter stage to an isolated DC / DC converter stage. Figure 10 The example shown includes a circuit with a large C F1 The capacitor-based PFC stage provides bulk voltage energy storage for line brownout protection and output power ride-through time. In addition, the PFC MRC does not provide inrush current, so no soft-start circuit is required. Any bulk voltage can be used, and the switch Q1 and input bridge rectifier can be replaced with a bridgeless PFC rectifier and first-stage switching circuit. RThe peak voltage can be charged up to 2 times the maximum peak input line voltage and needs to be below the minimum bulk voltage on CF1 to provide good PFC with the input AC waveform. R The minimum voltage across the L needs to be zero during each switching cycle to provide optimal PFC through each sine wave half cycle. R1 The charging current can then follow the rectified input line in proportion to Q1's duty cycle. This requires the second-stage Q3 switch to adjust or modulate the duty cycle to less than a 90-degree switching period within the full line rectified sine wave. PFC power supplies can use MRC buck-boost, boost-buck, or boost-boost converters for different applications.

[0099] Figure 11A 、 11B , 12A and 12B illustrate examples where the MRC topology described herein (e.g., Figure 1 An MRC topology) can be used in a DC / DC isolated MRC with a forward converter transformer stage to form a power supply circuit. In one example, the circuit 130 includes an isolated MRC buck-buck step-down-step-down voltage converter ( Figure 11A In another example, the circuit 132 forms an isolated MRC resonant buck-boost step-down-step-up voltage converter with two switches and three synchronous rectifiers ( Figure 11B ). Figure 12A and 12B Example topologies are illustrated, generally designated 140 and 142 respectively, including an isolated MRC, flyback PWM control with resonant capacitor charge and synchronous rectifier as a first stage to a resonant buck or resonant boost second stage.

[0100] It is important to understand that Figure 10 、 Figure 11A 、 Figure 11B 、 Figure 12A and Figure 12B The circuits shown are examples only, and the MRC topologies described herein can be incorporated into any other types of circuits or topologies to create other types of circuits for implementation in other applications.

[0101] The multi-resonant converter (MRC) power supply circuit described herein can be used in any type of power supply application, including network equipment (e.g., servers, routers, switches, gateways, controllers, edge devices, access devices, aggregation devices, core nodes, intermediate nodes, or other network devices). The network equipment can operate in the context of a data communication network that includes multiple network devices and can communicate through one or more networks.

[0102] A network device may be a programmable machine implemented in hardware, software, or any combination thereof. The network device may include one or more processors, memory, and a network interface. The memory may be a volatile memory or a non-volatile storage device that stores various applications, operating systems, modules, and data for execution and use by the processor. The logic may be encoded in one or more tangible media for execution by the processor. For example, the processor may execute code stored in a computer-readable medium (e.g., a memory). The computer-readable medium may be, for example, electronic (e.g., RAM (random access memory), ROM (read-only memory), EPROM (erasable programmable read-only memory)), magnetic, optical (e.g., CD, DVD), electromagnetic, semiconductor technology, or any other suitable medium. The network interface may include one or more line cards, fabric cards, service cards, router processor cards, controller cards, or other cards, elements, or components, and the POL converter may be located on one or more cards. It should be understood that the network device described herein is merely an example, and the embodiments described herein may be implemented on network devices of different configurations.

[0103] Although the method and apparatus have been described with reference to the illustrated embodiments, it will be readily apparent to those skilled in the art that modifications may be made to the embodiments without departing from the scope of the invention. It is therefore intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

1. A multi-resonant converter device comprising: a first stage comprising a first active switch, a first resonant inductor, a resonant capacitor, and a first synchronous rectifier; as well as a second stage comprising a second active switch, a second resonant inductor, a filter capacitor, and a second synchronous rectifier, wherein the first synchronous rectifier and the second synchronous rectifier are connected in parallel with the resonant capacitor and the filter capacitor; The first stage and the second stage form a non-isolated multi-resonant converter for converting a DC input voltage into a DC output voltage, and the device includes an input isolation stage.

2. The apparatus of claim 1, wherein the non-isolated multi-resonant converter comprises a step-down voltage converter.

3. The apparatus of claim 1, wherein the non-isolated multi-resonant converter comprises a step-up voltage converter.

4. The apparatus of claim 1 , wherein the first resonant inductor and the second resonant inductor operate with current in a discontinuous mode and wherein a voltage at the resonant capacitor discharges to zero over each of a plurality of cycles.

5. The apparatus of claim 1 , wherein the first resonant inductor and the second resonant inductor operate in a continuous mode with current and wherein a voltage at the resonant capacitor discharges to non-zero over each of a plurality of cycles.

6. The apparatus of claim 1 , wherein the first stage and the second stage operate in a discontinuous current mode with a switch zero current on and wherein the first stage operates with zero current off and the second stage operates with zero current on at a maximum duty cycle.

7. The apparatus of claim 1, wherein the apparatus is operable to regulate output voltage and current using frequency modulation.

8. The apparatus of claim 1, wherein the first stage is configured to use pulse width modulation to adjust the charge stored on the resonant capacitor to regulate the output voltage and current.

9. The apparatus of claim 1, wherein the second resonant inductor comprises a tapped inductor.

10. The apparatus of claim 1, wherein the apparatus comprises a power factor correction stage.

11. A multi-resonant converter device comprising: A card for insertion into a network device, the card comprising a point-of-load power supply, the point-of-load power supply comprising: a first stage comprising a first switch, a first inductor, a resonant capacitor, and a first synchronous rectifier; and a second stage comprising a second switch, a second inductor, a filter capacitor, and a second synchronous rectifier, wherein the first synchronous rectifier and the second synchronous rectifier are connected in parallel with the resonant capacitor and the filter capacitor; Wherein the first stage comprises a power regulation resonant stage and the second stage comprises a voltage converter resonant stage to form a non-isolated multi-resonant converter, and the apparatus comprises an input isolation stage.

12. The apparatus of claim 11, wherein the point-of-load power supply eliminates the need for an intermediate bus converter on the card.

13. The apparatus of claim 11, wherein the second inductor comprises a tapped resonant inductor.

14. The apparatus of claim 11, wherein the first stage is configured to regulate output voltage and current using pulse width modulation or frequency modulation.

15. A point-of-load power supply, comprising: a first stage comprising a first active switch, a resonant inductor, a resonant capacitor, and a first synchronous rectifier; as well as a second stage comprising a second active switch, a tapped resonant inductor, a filter capacitor, and a second synchronous rectifier, wherein the first synchronous rectifier and the second synchronous rectifier are connected in parallel with the resonant capacitor and the filter capacitor; The first stage and the second stage form a non-isolated multi-resonant converter for converting a DC input voltage into a DC output voltage by step-down voltage conversion or step-up voltage conversion, and the point-of-load power supply includes an input isolation stage.

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